Award type：Award from publisher, newspaper, foundation, etc.  Country：Japan

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Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

Award type：Award from publisher, newspaper, foundation, etc.  Country：Japan

Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

Award type：Award from publisher, newspaper, foundation, etc.  Country：Japan

Award type：Award from international society, conference, symposium, etc.  Country：Japan

Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

Award type：Award from publisher, newspaper, foundation, etc.  Country：Japan

Award type：Honored in official journal of a scientific society, scientific journal  Country：Germany

Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

Country：Japan

Award type：Award from international society, conference, symposium, etc.  Country：Japan

Award type：Award from international society, conference, symposium, etc.  Country：Japan

Award type：Award from international society, conference, symposium, etc.  Country：Japan

Award type：Award from publisher, newspaper, foundation, etc.  Country：Japan

Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

Award type：Award from publisher, newspaper, foundation, etc.  Country：Japan

Award type：Award from Japanese society, conference, symposium, etc.  Country：Japan

Award type：Award from publisher, newspaper, foundation, etc.  Country：Japan

Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Fuji Technology Press Ltd.  

Articulated robots are widely used in industries because they can perform manufacturing tasks with complicated movements. Higher speed and accuracy of motions are always required to improve the quality and productivity of products. The vibration characteristics of the robots are an important factor to achieve higher speed and accuracy motions. Robots are increasingly being used for machining. The vibration characteristics must also be considered when designing proper cutting conditions for the machining. To design control and cutting strategies for higher speed and accuracy motions or higher productivity of the machining process, it is effective to investigate the vibration characteristics of the robot and develop a mathematical model which can represents the vibration characteristics. The aim of this study is to investigate the vibration characteristics of an architectural robot and develop a mathematical model which can represent the dynamic behavior of the robot. To achieve this, vibration mode of an industrial architectural robot is analyzed based on measured frequency characteristics. According to the results of the modal analysis, it was clarified that the axial and angular stiffness of bearings of each joint of the robot has a significant impact on the vibration characteristics. Therefore, in this study, a mathematical model of the robot is developed considering the joint bearing stiffness. The mathematical model that also considers the kinematics of the robot, stiffness of reduction gears, control system for motors, and disturbance, such as friction and gravity, is introduced into the model. The control system is precisely modeled based on actual control algorithm in accordance with the implemented source codes. Although mass and inertia of the links are obtained from the 3D-CAD model, stiffness and damping parameters of the bearings and reduction gears are identified by matching the measured and simulated frequency responses. It has been confirmed that the model can adequately represents the vibration mode of the actual robot. Circular motion tests were performed to verify the model. Motion trajectories of the end effector were measured and simulated. As a result, it has been confirmed that the developed model is effective to analyze the dynamic behaviors.

DOI： 10.20965/ijat.2021.p0631

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.precisioneng.2021.02.009

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.precisioneng.2021.02.011

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：MDPI AG  

A cubic-machining test has been proposed to evaluate the geometric errors of rotary axes in five-axis machine tools using a 3 × 3 zone area in the same plane with different tool postures. However, as only the height deviation among the machining zones is detected by evaluating the test results, the machining test results are expected to be affected by some error parameters of tool sides, such as tool length and profile errors, and there is no research investigation on how the tool side error influences the cubic-machining test accuracy. In this study, machining inaccuracies caused by tool length and tool profile errors were investigated. The machining error caused by tool length error was formulated, and an intentional tool length error was introduced in the simulations and actual machining tests. As a result, the formulated and simulated influence of tool length error agreed with the actual machining results. Moreover, it was confirmed that the difference between the simulation result and the actual machining result can be explained by the influence of the tool profile error. This indicates that the accuracy of the cubic-machining test is directly affected by tool side errors.

DOI： 10.3390/jmmp5020051

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Language：Japanese   Publisher：Journal of Advanced Mechanical Design, Systems and Manufacturing  

In end milling, proper tool life management is crucially important for achieving highly accurate machining, avoiding tool failure, and optimizing production costs. In recent years, a number of tool condition monitoring (TCM) methods aimed at improving tool life management have been proposed. However, these methods have generally been impractical, and tool life still tends to be determined based on machining time or the quantity of the product produced. To address this shortcoming, a practical online TCM method is proposed. The proposed method is based on the idea that the frictional force acting on the flank face of a tool increases with increasing flank wear resulting from an increase in the contact surface area between the flank face and the machined surface. The implication is that tool wear can be indirectly monitored using the change in frictional force on the flank face, which can be determined by tracking the spindle motor torque obtained using a computerized numerical control (CNC) controller and a real time cutting force simulation. The influence of tool wear is not considered in the simulation model; rather, the frictional force is estimated from the difference between the average predicted cutting torque and the average monitored spindle motor torque. With the proposed method, no additional sensor is needed to monitor tool wear. Additionally, no parameter determination is necessary to perform the simulation because the parameters needed for the simulation are immediately determined at the beginning of the milling operation based on the monitored spindle motor torque. Thus, the TCM method proposed here offers a practical online alternative.

DOI： 10.1299/jamdsm.2021jamdsm0077

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Language：Japanese   Publisher：10th International Conference on Leading Edge Manufacturing Technologies in 21st Century, LEM 2021  

This study proposes an evaluation method for the coupling characteristics based on the measured frequency function. Stiffness and damping can be identified from the resonance frequency and maximum vibration amplitude at the resonance frequency, respectively. Characteristics of various types of coupling; leaf-spring type couplings and a resin type coupling are evaluated by the proposed method to compare the difference of the characteristics. As the results, it is confirmed that the proposed evaluation method can adequately evaluate the coupling stiffness and damping characteristics. In addition, the difference of the characteristics of different types and structures of coupling can be evaluated and compared by the proposed method.

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Mechanical Engineers  

DOI： 10.1299/jamdsm.2021jamdsm0060

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Language：Japanese   Publisher：10th International Conference on Leading Edge Manufacturing Technologies in 21st Century, LEM 2021  

Contact between the tool and the workpiece during machining has a significant effect on the vibration characteristics of the machine tools. In this study, contacting rate is defined as the contact time per unit time based on the detected contact between the tool and workpiece during the excitation tests, and relationship between the contacting rate and vibration characteristics is investigated. As a result, it was confirmed that the natural frequency increased significantly when the contacting rate was over 90%, and the vibration damping increased significantly when the contacting rate was in the range of 0-10%.

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Language：Japanese   Publisher：10th International Conference on Leading Edge Manufacturing Technologies in 21st Century, LEM 2021  

The purpose of this study is to propose a practical tool condition monitoring method in end milling operation. In the proposed method, real-time cutting force simulation is performed in parallel with actual milling operation. The tool condition is recognized by comparing the spindle motor torque, which can be monitored through CNC without additional sensors, with the predicted cutting torque. This method is practical because the parameter required for real-time cutting force simulation can be immediately and automatically identified at the beginning of the milling operation, and it requires no additional sensor installation. The effectiveness of this method was confirmed by the experimental verifications.

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Authorship：Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Mechanical Engineers  

<p>It is expected that the vibration characteristics of NC machine tools are affected by the contact between tool and workpiece during the cutting operations. However, the influences of the contact have not been clarified up to now. This study investigates the influence of contact between tool and workpiece onto vibration characteristics of machine tools. In this study, frequency response of a vertical type milling machine during cutting operation is evaluated. The evaluation tests of the contacting effect are carried out with and without cutting operations. In order to clearly evaluate the influence of the contact between a tool edge and a workpiece, boring operations of 50 mm diameter are carried out. The frequency responses are measured by using feed motor torque. Impulse signal is applied to the motor torque command during the cutting operations to oscillate the machine tool, and the axial acceleration of the table is measured to obtain the frequency responses. The impulse signal can be applied by refereeing the spindle rotational angle to control the relationships between the cutting edge and workpiece surface. As the results of the evaluations, it is clarified that the proposed method can evaluate the influence of the contact adequately. The natural frequency slightly increases and the vibration amplitude decreases when the tool contacts with the workpiece, regardless of whether non cutting or cutting. It has also been confirmed that the vibration amplitude of the frequency characteristics is changed due to the contact length of the cutting edge.</p>

DOI： 10.1299/transjsme.20-00185

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Language：Japanese   Publisher：The Japan Society for Precision Engineering  

<p>Cutting force is one of the most important information in order to know machining process and optimize cutting conditions in end milling. An external sensor like a dynamometer is widely used to measure cutting force in the most researches. However, using a dynamometer is inadequate to measure cutting force practically in factories. Thus, the sensor-less cutting force monitoring method is proposed in this study. Cutting force is predicted by the real time end milling simulator, and the predicted cutting force is synchronized with the actual cutting force in the proposed method. The required parameters for the cutting force prediction can be determined from the spindle motor toque monitored without any additional sensors, and can be determined within 10 seconds at the beginning of milling operation without any additional cutting test. The predicted milling force has good agreement with the milling force measured by a dynamometer. Therefore this method can be used practically as the sensor-less cutting force monitoring method in factories.</p>

DOI： 10.2493/jjspe.86.708

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

© 2020 Elsevier Inc. An experimental analysis of the mechanical and electrical power consumption of feed drive systems is presented in this paper. The main components affecting the power consumption are the motor, bearings, ball-screw, and table. The power consumption of the motor has been investigated experimentally through the study of the electrical efficiency. The efficiency has been calculated from the acquired angular velocity and supplied torque for several velocities and loads. The study shows how the working conditions of the motor heavily influence the efficiency of the motor and therefore the power consumption of the whole feed drive system. Moreover, the mechanical power consumption of each component of the feed drive has been investigated, showing that the main component responsible for the consumption is the ball-screw. Thus, in order to clarify the influence of the constructive parameters of the ball-screw on the power consumption, four kinds of ball-screws differing in the lead dimension and the preload condition have been considered. Furthermore, it clarifies the relation between the power consumption of the feed drive system and the working velocity of the table. Finally, the advantages and disadvantages of each feed drive mechanical configuration are discussed, emphasizing that the driven factor that affects the power consumption the most is the angular velocity, due to the trade-off between the motor efficiency and the mechanical power loss from the friction of the components in relative motion. This research can help the selection of the lead of the ball-screw, from an energetic point of view, in order to get higher efficiency of the feed drive.

DOI： 10.1016/j.precisioneng.2020.04.016

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

© 2019 Elsevier Inc. Five-axis machine tools, which combine three linear axes and two rotary axes, are required for accuracy in machining complex shapes. In this paper, to clarify the influence of simultaneous three-axis control motion measurements as specified in ISO 10791-6, the measured results using a ball bar and R-test are compared. As the motion trajectories of the linear axes are not identical in both measurement devices, it is expected that the error motions of the linear axes cause different measurement results depending on the measurement devices. Thus, the squareness errors between the linear axes and the error motions of the linear axes are assumed as error factors that influence the measured results in this study. A mathematical model of a five-axis control machine tool that considers the error motions and squareness errors of the linear axis is constructed, and the influence of those error factors on motion accuracy is examined using an experiment and a simulation. As a result, the squareness errors and error motions of the linear axis are observed to greatly affect simultaneous three-axis controlled motion accuracy.

DOI： 10.1016/j.precisioneng.2019.10.011

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

© 2019 Elsevier Inc. A higher machining ability is always required for NC machine tools to achieve higher productivity. The self-oscillated vibration called “chatter” is a well-known and significant problem that increases the metal removal rate. The generation process of the chatter vibration can be described as a relationship between cutting force and machine tool dynamics. The characteristics of machine tool feed drives are influenced by the nonlinear friction characteristics of the linear guides. Hence, the nonlinear friction characteristics are expected to affect the machining ability of machines. The influence of the contact between the cutting edge and the workpiece (i.e., process damping) on to the machining ability has also been investigated. This study tries to clarify the influence of the nonlinear friction characteristics of linear guides and ball screws and process damping onto milling operations. A vertical-type machining center is modeled by a multi-body dynamics model with nonlinear friction models. The influence of process damping onto the machine tool dynamics is modeled as stiffness and damping between the tool and the workpiece based on the evaluated frequency response during the milling operation. A time domain-coupled simulation approach between the machine tool behavior and the cutting forces is performed by using the machine tool dynamics model. The simulation results confirm that the nonlinear frictions influence the cutting forces with an effect to suppress the chatter vibration. Furthermore, the influence of process damping can be evaluated by the proposed measurement method and estimated by a time domain simulation.

DOI： 10.1016/j.precisioneng.2019.10.010

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Mechanical Engineers  

© 2020 The Japan Society of Mechanical Engineers. In this study, we describe a novel mechanical vibration suppression method for high-speed contouring motions. In this method, vibration compensation torque was applied to suppress mechanical vibrations during high-speed contouring motions. The parameters of the compensation signal were determined using commanded acceleration and time for acceleration and deceleration, which were set as numerical control (NC) parameters. We also propose an autonomous compensation-torque-generation algorithm based on the acceleration command from NC. The effectiveness of this method was assessed by measuring and simulating rectangular corner contouring motions in which the compensation torque is applied. The results confirmed that the proposed method can effectively suppress the vibration when the motion direction changes. This method can also be effectively performed at various feed speeds by automatically adapting the torque based on the proposed criteria.

DOI： 10.1299/jamdsm.2020jamdsm0005

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Language：Japanese   Publisher：JSME 2020 Conference on Leading Edge Manufacturing/Materials and Processing, LEMP 2020  

It is expected that the vibration characteristics of NC machine tools are affected by the contact between the tool and the workpiece during the cutting operations. However, the influences of the contact have not been clarified up to now. In this study, a method to evaluate the contacting effect and evaluated results are described. Frequency response of a vertical type milling machine during cutting operation is evaluated in this study. The evaluation tests of the contacting effect are carried out with and without cutting operations. In order to clearly evaluate the influence of the contact between a tool edge and a workpiece, boring operations of 50 mm diameter are carried out. The frequency responses are measured by using feed motor torque. Impulse signal is applied to the motor torque command during the cutting operations to oscillate the machine tool, and the axial acceleration of the table is measured to obtain the frequency responses. The impulse signal can be applied by refereeing the spindle rotational angle to control the relationships between the cutting edge and workpiece surface. As the results of the evaluations, it is clarified that the proposed method can evaluate the influence of the contact adequately. The natural frequency slightly increases and the vibration amplitude decreases when the tool contacts with the workpiece, regardless of whether non-cutting or cutting. It has also been confirmed that the vibration amplitude of the frequency characteristics is changed due to the contact length and the relative direction of the cutting edge.

DOI： 10.1115/LEMP2020-8518

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Language：Japanese   Publisher：JSME 2020 Conference on Leading Edge Manufacturing/Materials and Processing, LEMP 2020  

This study presents an experimental analysis of the power consumption of feed drive systems. The relevant system components from the power consumption point of view are the motor, bearings, ball-screw and linear guides. The electric power consumption of the motor is investigated experimentally acquiring the inputted voltage and the current; then, through the study of its efficiency, it is shown that the electric efficiency of the motor heavily depends on the angular velocity and the supplied torque. The mechanical power consumption of each component of the feed drive is investigated showing that the component that affects the most the consumption is the ball-screw. Thus, four kind of ball-screws differing for the lead of the screw and the preload of screw-nut are investigated; it is clarified the relation between the mechanical power consumption and several system characteristics such as the lead of the screw, the preload condition, and the table working velocity. Finally, the advantages and disadvantages of each mechanical configuration of the feed drive are discussed, emphasizing that the most important driven factor of the power consumption is the angular velocity due to the trade-off between the motor efficiency and the mechanical power loss of the system components cause friction.

DOI： 10.1115/LEMP2020-8523

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Language：Japanese   Publishing type：Research paper (scientific journal)  

© 2020, Fuji Technology Press. All rights reserved. While evaluating the accuracy of high-precision machine tools, it is critical to reduce the error factors contributing to the measured results as much as possi-ble. This study aims to evaluate both the error motions and geometric errors of the rotary axis without considering the influence of motion error of the linear axis. In this study, only the rotary axis is moved considering two different settings of a reference sphere, and the linear axes are not moved. The motion accuracy of the rotary axis is measured using the R-test device, both the error motions and geometric errors of the rotary axis are identified from the measurement results. Moreover, the identified geometric errors are verified for correctness via measurement with an intentional angular error. The results clarify that the proposed method can identify the error motions and geometric errors of a rotary axis correctly. The method proposed in this study can thus be effective for evaluating the motion accuracy of the rotary axis and can contribute to further improvement of the accuracy of the rotary table.

DOI： 10.20965/IJAT.2020.P0399

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Language：Japanese   Publisher：2020 International Symposium on Flexible Automation, ISFA 2020  

Motion error of machine tool feed axes influences the machined workpiece accuracy. However, the influences of each error sources are not identical; some errors do not influence the machined surface although some error have significant influences. In addition, five-axis machine tools have more error source than conventional three-axis machine tools, and it is very tough to predict the geometric errors of the machined surface. This study proposes a method to analyze the relationships between the each error sources and the error of the machined surface. In this study, a kind of sphere-shaped workpiece is taken as a sample to explain how the sensitivity analysis makes sense in ball-end milling. The results show that the method can be applied for the axial errors, such as motion reversal errors, to make it clearer to obverse the extent of each errors. In addition, the results also show that the presented sensitivity analysis is useful to investigate that how the geometric errors influence the sphere surface accuracy. It can be proved that the presented method can help the five-axis machining center users to predict the machining errors on the designed surface of each axes error motions.

DOI： 10.1115/ISFA2020-9610

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Japan Society of Mechanical Engineers  

<p>A new methodology to assess and adapt cutting conditions for machining operation planning is proposed in this study. In order to automate machining operation planning, the method to reuse cutting conditions in the past previous machining operations has been proposed in the previous study. However, the assessment and adaptation of cutting conditions are required to apply the referred cutting conditions to the different situation. For the assessment of cutting conditions, an acceptable area to select cutting conditions (AACC) is calculated. The AACC is restricted by several constraints such as spindle power capacity and maximum feed speed of machine tools, torsional and bending strength of cutting tools and so on. In the case that the referred cutting conditions keep in the AACC, the referred cutting condition can be applied to the situation without any revision. In the case that the referred cutting conditions keep out the AACC, the referred cutting conditions cannot be applied to the situation and should be adapted for the objective machining operation. In this study, the referred cutting conditions are adapted so as to keep the machining efficiency such as machining time, tool life and cusp height. This study considers that these three aspects are essential for skillful operators to determine the cutting conditions. The feasibility of this methodology is demonstrated in the case study and cutting experiments. This methodology can assess and adapt the referred cutting conditions for the objective machining operation.</p>

DOI： 10.1299/transjsme.20-00153

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Language：Japanese   Publisher：Proceedings of SPIE - The International Society for Optical Engineering  

The X-Ray Imaging and Spectroscopy Mission (XRISM) is the successor to the 2016 Hitomi mission that ended prematurely. Like Hitomi, the primary science goals are to examine astrophysical problems with precise high-resolution X-ray spectroscopy. XRISM promises to discover new horizons in X-ray astronomy. XRISM carries a 6 x 6 pixelized X-ray micro-calorimeter on the focal plane of an X-ray mirror assembly and a co-aligned X-ray CCD camera that covers the same energy band over a large field of view. XRISM utilizes Hitomi heritage, but all designs were reviewed. The attitude and orbit control system were improved in hardware and software. The number of star sensors were increased from two to three to improve coverage and robustness in onboard attitude determination and to obtain a wider field of view sun sensor. The fault detection, isolation, and reconfiguration (FDIR) system was carefully examined and reconfigured. Together with a planned increase of ground support stations, the survivability of the spacecraft is significantly improved.

DOI： 10.1117/12.2565812

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Language：Japanese   Publisher：JSME 2020 Conference on Leading Edge Manufacturing/Materials and Processing, LEMP 2020  

Several methods have been proposed to detect tool wear in milling operation using AE (Acoustic Emission) signals or cutting force signals. However, these methods require additional sensors such as an AE sensor or a dynamometer, which incurs additional costs. For this reason, a simple tool life estimation method based on machining time is used. In this study, a sensor-less tool wear estimation method is proposed. In this method, the parameters required for the cutting force prediction are identified continuously from the spindle motor torque signal, which can be monitored within the computer numerical controlled (CNC) machine. The tool wear progress can be estimated by the continuous change in the identified parameters during milling operation. To identify the parameters continuously, a real-time virtual milling simulation is performed in parallel with a physical milling operation. In the experimental results, it was confirmed that the identified parameter corresponding to the edge force component has linear relationship with the flank wear width of cutting edge. Thus the flank wear can be estimated without any additional sensor.

DOI： 10.1115/LEMP2020-8628

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier  

© 2019 Elsevier Inc. Five-axis machine tools, consisting of three translational axes and two rotary axes, are increasingly being used for complex surface machining. This paper proposes a new sensitivity analysis method to elucidate the relationship between the tool trajectory error and the error motions of the feed axes. Based on the free-curve trajectory during simultaneous five-axis machining, a surface coordinate system is created for each tool center point, to define the tool trajectory and the trajectory errors. Then, a novel sensitivity coefficient is defined to investigate the relationship between the trajectory error and the error motions. It is shown that the proposed sensitivity analysis method can successfully determine whether the trajectory is sensitive to the error motions, based on sensitivity analyses performed during conic frustum machining and S-shaped machining tests. Moreover, the sensitivity analysis method can also predict the effects of the error motion source, such as the reversal errors. In the future, we intend to study other types of machining processes, such as ball-end milling, as well.

DOI： 10.1016/j.precisioneng.2019.07.006

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier  

© 2019 Elsevier Inc. Motion accuracy of the feed drive systems deteriorate due to wear of the bearing and ball screw during the long term use. It is known that the wear makes larger positioning reversal value. In this study, a sensor-less estimation method for the positioning reversal value of ball screw driven feed drive systems based on the servo signals is proposed. The proposed method analyses the relationship between amplitude of feedback position and motor torque during swept sine wave motion. It is experimentally confirmed that the proposed method can estimate the positioning reversal values adequately.

DOI： 10.1016/j.precisioneng.2019.06.011

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier  

© 2019 Elsevier Inc. In this paper, we propose to develop a novel disturbance force compensator to effectively suppress quadrant glitches in a feed drive system using a linear motor and linear motion ball guides (LMBGs). In the circular motions, feed drive systems using LMBGs generate a following error called quadrant glitches at the motion direction changing point of each axis. Quadrant glitches are engendered by disturbance force due to friction, and disturbance force compensation is necessary to compensate quadrant glitches. A disturbance observer is a disturbance force compensation method in the motion control field. If a disturbance observer causes quadrant glitch compensation, the height of quadrant glitches decreases. However, after a quadrant glitch, a deviation with a sign opposite to that of the quadrant glitch, called “inverse response”, is generated. An inverse response degrades the contouring motion accuracy and causes an excessive cutting of the cylindrical process. The proposed compensator, called a “disturbance suppressor”, presents two advantages over an ordinary disturbance observer: 1) there is no inverse response, and 2) the compensator exhibits a superior quadrant glitch compensation capability. The disturbance suppressor has two structural differences compared to an ordinary disturbance observer: 1) a pull-off point and a summing point are interchanged, and 2) two gain constants, K and β, are added to a disturbance observer. In this study, we investigate the causes of the inverse response suppression and quadrant glitch compensation improvement when applying the disturbance suppressor. We also propose a gain tuning method for the disturbance suppressor in a quadrant glitch compensation based on our results. The effectiveness of this compensator was verified by experiments using a feed-drive system. In the case of applying the disturbance observer, the height of the quadrant glitch was 10.4 nm and the amplitude of the inverse response was 3 nm. In the case of applying the optimized disturbance suppressor, the height of the quadrant glitch was 7.7 nm and there was no inverse response.

DOI： 10.1016/j.precisioneng.2019.05.007

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Language：Japanese   Publisher：THE INSTITUTE OF SYSTEMS, CONTROL AND INFORMATION ENGINEERS (ISCIE)  

<p>According to the change of manufacturing style from mass production to customized production, it is important to manage the process plan and to control the machining quality of products. On machine measurement (OMM) has an advantage that it eliminates the operations of remove and reattachment of the workpiece and eliminates the positioning error at the reattachment. The contact measurement using a touch probe is one of the OMM. However, this measurement requires decision of measuring points and paths in order to conduct the measurement using touch probe. Currently, measuring paths of the touch probe is generated by an operator who can recognize the shape of the workpiece, determine the measuring regions and the measuring points. The objective of this study is automatically generation of the NC program to instruct OMM using a touch probe. This study realizes automatically generation of the NC program to instruct OMM by focusing on recognition of the geometrical property of the product shape based on the removal volume and determination of the measuring points and paths.</p>

DOI： 10.5687/iscie.32.212

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Language：Japanese   Publishing type：Research paper (scientific journal)  

© 2018 Elsevier Inc. Programs for machining curved shapes with CNC (computerized numerical control) machine tools are commonly generated of approximated linear segments based on a set chord error, the so-called ‘tolerance’ on CAM (computer aided manufacturing) software operation. It is considered that smaller amount of chord error leads to higher machining accuracy. It is also empirically known that the chord error influences the machining time or the movement speed of the machine tool. However, there is no theoretical procedure to set the appropriate chord error for the CNC programs, to reduce the machining error but not decrease the feed speed as much as possible from the commanded one. In this research, we propose a method for calculating a suitable chord error from the curvature radius, commanded feed rate, and CNC block-processing time to generate programs considering the chord error. The results of experiments confirmed higher speed and accuracy of movements with CNC machine tools using programs generated by this method.

DOI： 10.1016/j.precisioneng.2018.08.004

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© 2019, Fuji Technology Press. All rights reserved. ISO 10791-7, the test standard for machining centers, was revised in 2014 to add the test method for fiveaxis machining centers. However, an S-shaped test was additionally proposed as an accuracy test of aircraft parts from China immediately before the establishment of the test standard. In an ISO meeting, various problems such as creating three-dimensional models and evaluation items have been indicated for the proposed test method. By revising these problems, the standard was finally completed and will be introduced as an informative annex soon. However, it is still an inappropriate test method from the viewpoint of performance inspection for machine tools. In this research, the S-shaped test method draft proposed in September 2016 is tested using two types of five-axis machining centers and commercial CAM software. Consequently, a hidden problem is revealed, that is, an abruptmovement that affected the final result is added to the machine because the rotation direction of the rotary axes is not ideal. This is attributed to the performance of the CAM software’s post processor that converts from CL data to NC program. This study provides some insights into avoiding the problem and obtaining better test results.

DOI： 10.20965/ijat.2019.p0593

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

© 2019 ASME. On-machine measurement (OMM) is introducing to Numerical Control (NC) machine tools. By the OMM, a workpiece is measured on the machine tool (i.e., without loading and unloading), so OMM can reduce the setup time and positioning error for reloading a workpiece. OMM is used for the process control during machining because it is still difficult to suppress the machining error caused by the cutting process such as the tool deflection, the tool wear and the heat deformation during machining. There are several approaches to on-machine measurement, including non-contact measurements using a laser displacement sensor or imaging equipment and contact measurements using a touch probe. However, to conduct OMM with a touch probe it is necessary to generate an NC program by operators. Moreover, for the process control and monitoring, the information of machining process should be considered in the measuring plan. For process control, measurement of a region that affects machining in the next process should be conducted during the machining process (i.e., after the machining of that region). Furthermore, when some machining abnormality that affects product quality occurs during the machining process, the abnormality should be detected and measured at an early stage to avoid unnecessary machining. This study aims to realize the automation of planning for onmachine measurement, where measurement is conducted at the necessary time during the machining process based on process planning for the early detection of machining abnormality. Furthermore, when a machining abnormality is detected based on the measurement results, the proposed system automatically judges whether to stop machining or to re-machine the affected region.

DOI： 10.1115/MSEC2019-2995

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Language：Japanese   Publishing type：Research paper (scientific journal)  

© 2019, Fuji Technology Press. All rights reserved. As the motion accuracy of 5-axis machining centers directly influences the geometrical shape accuracy of the machined workpieces, accuracy enhancement of the 5-axis machining centers is strongly needed. To improve the shape accuracy during the machining by a 5-axis machine tool, a method that modifies the CL-data based on the motion trajectory errors normal to the machined surface at each command point has been proposed. In this study, the proposed method is applied to simultaneous 5-axis controlled machining to improve motion accuracy. A normal vector calculation method for the simultaneous 5-axis controlledmotion is newly proposed, and the compensation method is applied to turbine blade machining by 5-axis controlled motion. Measurement tests of the cutting motion for blade shape machining by a ball-end mill were carried out with a different control mode of NC. The CL-data for the machining tool path was also modified based on the calculated trajectory of the tool center point. Experimental results reveal that the feed speed and machining accuracy significantly depend on the control mode of NC, and that the shape accuracy can be improved by applying the proposed compensation method without any decrease in motion speed.

DOI： 10.20965/ijat.2019.p0583

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

© 2019 The Japan Society of Mechanical Engineers In this research, we propose a method to evaluate both speed and accuracy performance of CNC machine tools at the same time. An important facet of the contouring performance of machine tools with computer numerical control (CNC) is the machining of workpieces within the desired accuracy and within as short a time as possible. For this reason, a method for evaluating speed and accuracy in the two dimensions of speed and error based on the actual trajectory, which is the actual movement trajectory with respect to the linear axes of CNC machine tools, has been proposed. In this research, we explain the method proposed for linear axes and propose a method to evaluate the speed and accuracy of a rotary axis and a linear axis in the two dimensions of speed and error by introducing a cylindrical surface to the combined movement of the rotary and linear axes. With experiments, we quantitatively evaluated the speed and accuracy of multiple CNC machine tools using two-dimensional representation with graphs of the actual speed and maximum error for the combined movement of a rotary axis and a linear axis.

DOI： 10.1299/jamdsm.2019jamdsm0022

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© 2019 The Japan Society of Mechanical Engineers To improve machining efficiency, it is necessary to know the machining status and optimize cutting conditions. Cutting force prediction is one method of determining the machining status. The instantaneous rigid force model is widely used and can be easily applied to cutting force prediction. However, this model requires six parameters called cutting coefficients, which have to be determined in advance through a preliminary experimental cutting test. Therefore, in this study, a new cutting force prediction method that does not require a cutting test is proposed to enable the practical understanding of the milling process in a factory setting. For this purpose, the conventional instantaneous rigid force model was revised based on the oblique cutting model and the orthogonal cutting theory to reduce the number of cutting parameters required for cutting force prediction. In the proposed model, only the shear angle is required for cutting force prediction. In practical situations, the shear angle can be identified immediately from the measured spindle motor torque, which can be monitored without any additional sensors at the start of milling operation, and the milling forces can then be predicted. In the proposed force model, the effect of tool runout can be expressed by considering the rotational radius deviation at each cutting edge. In addition, tool chipping can be detected by comparing the monitored and predicted torques. To validate the effectiveness of the proposed model, cutting experiments were conducted. The predicted force showed good agreement with the measured one. The similarity between the monitored and predicted torques was decreased by tool chipping. These results indicate that the in-process machining status can be understood and tool chipping can be detected practically without any experimental milling to determine the required parameters for prediction or any additional force sensors.

DOI： 10.1299/jamdsm.2019jamdsm0052

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© 2019 ASME. Five-axis machining center, combined three linear and two rotary axes, has been increasingly used in complex surface machining. However, as the two additional axes, the machined surface under table coordinate system is usually different from the tool motion under machine coordinate system, and as a result, it is very tough to predict the machined shape errors caused by each axes error motions. This research presents a new kind of sensitivity analysis method, to find the relationship between error motions of each axis and geometric errors of machined shape directly. In this research, the S-shaped machining test is taken as a sample to explain how the sensitivity analysis makes sense. The results show that the presented sensitivity analysis can investigate how the error motions affect the S-shaped machining accuracy and predicted the influence of error motions on certain positions, such as the reversal errors of the axes around motion reversal points. It can be proved that the presented method can help the five-axis machining center users to predict the machining errors on the designed surface of each axes error motions.

DOI： 10.1115/MSEC2019-2804

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© 2018, Fuji Technology Press. All rights reserved. A new methodology to generate instruction commands for real-time machine control instead of preparing NC programs is developed under the CAM-CNC integration concept. A machine tool based on this methodology can eliminate NC program preparation, achieve cutting process control, reduce production lead time, and realize an autonomous distributed factory. The special feature of this methodology is the generation of instruction commands in real time for the prompt machine control instead of NC programs. Digital Copy Milling (DCM), which digitalizes copy milling, is realized by referring only to the CAD model of the product. Another special feature of this methodology is the control of the tool motion according to the information predicted by a cutting force simulator. This feature achieves both the improvement in the machining efficiency and the avoidance of machining trouble. In this study, the customized end milling operation of a dental artificial crown is realized as an application using the new methodology mentioned above. In this application, the CAM operation can be eliminated for the NC program generation, and tool breakage can be avoided based on the tool feed speed control from the predicted cutting force. The result shows that the new methodology has good potential to achieve customized manufacturing, and can realize both high productivity and reliable machining operation.

DOI： 10.20965/ijat.2018.p0947

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© 2018, Fuji Technology Press. All rights reserved. The motion trajectories of machine tools directly influence the geometrical shape of machined workpieces. Hence, improvement in their motion accuracy is required. It is known that machined shape errors occurring in numerical control (NC) machine tools can be compensated for by modifying the CL-data, based on the amount of error calculated by the measurement results of the machined shape of the workpiece. However, by using this method the shape errors cannot be compensated accurately in five-axis machining, because the final machining shape may not reflect the motion trajectory of a tool owing to the motion errors of the translational and rotary axes. In this study, a modification method of the cutter location (CL)-data, based on the amount of motion errors of the tool center-point trajectory during the machining motion, is newly proposed. The simulation and experiment of a wing profile machining motion is performed, to confirm the effectiveness of the proposed method. From the results, we confirm that the motion accuracy can be significantly improved by applying the proposed method.

DOI： 10.20965/ijat.2018.p0699

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DOI： 10.3390/jmmp2020021

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© 2018 by ASME. A new cutting force simulator has been developed to predict cutting force in ball end milling. In this simulator, uncut chip thickness is discretely calculated based on fully voxel models representing both cutting edge and instantaneous workpiece shape. In the previous simulator, a workpiece voxel model was used to calculate uncut chip thickness under a complex change of workpiece shape. Using a workpiece voxel model, uncut chip thickness is detected by extracting the voxels removed per cutting tooth for the amount of material fed into the cutting edge. However, it is difficult to define the complicated shape of cutting edge, because the shape of cutting edge must be defined by mathematical expression. It is also difficult to model the voxels removed by the cutting edge when tool posture is nonuniformly changed. Therefore, a new method to detect uncut chip thickness is proposed, one in which both cutting edge and instantaneous workpiece shape are fully represented by a voxel model. Our new method precisely detects uncut chip thickness at minute tool rotation angles, making it possible to detect the uncut chip thickness between the complex surface shape of the workpiece and the particular shape of the cutting edge. To validate the effectiveness of our new method, experimental five-axis milling tests using ball end mill were conducted. Estimated milling forces for several tool postures were found to be in good agreement with the measured milling forces. Results from the experimental five-axis milling validate the effectiveness of our new method.

DOI： 10.1115/1.4038499

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© 2018 by ASME. Energy consumption of numerical control (NC) machine tools is one of the key issues in modern industrial field. This study focuses on reducing the energy consumed by a five-axis machining center by changing only the workpiece setting position. Previous studies show that the movements along each axis in five-axis machining centers depend on the workpiece setting position, regardless of whether the same operation is performed. In addition, the energy consumptions required for the movements are different along each axis. From these considerations, an optimum workpiece setting position that can minimize the energy consumed during these motions is assumed to exist. To verify this assumption, in this study, the energy consumed by the feed drive systems of an actual five-axis machining center is first measured and then estimated using the proposed model in this study. The model for estimating the energy consumption comprises the friction, motor, and amplifier losses along each axis. The total energy consumption can be estimated by adding the energy consumptions along each axis. The effect of the workpiece setting position on the energy consumption is investigated by employing the cone-frustum cutting motion with simultaneous five-axis motions. The energy consumption that depends on the workpiece setting position is first measured and then estimated. The results confirm that the proposed model can estimate the energy consumption accurately. Moreover, the energy consumption is confirmed to depend on the workpiece setting position; the minimum energy consumption is found to be 20% lower than the maximum one.

DOI： 10.1115/1.4037427

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society for Precision Engineering  

© 2018 Seimitsu Kogaku Kaishi/Journal of the Japan Society for Precision Engineering. All rights reserved. This paper describes the results of nano-ordcr accuracy contouring control by quadrant glitch compensation for a feed drive system with eight grooved linear ball guide. Three kinds of compensation methods are applied and compared in this study Those arc; 1) repetitive control technique, 2) disturbance observer, and Ì) combination of the both. As (he results of experiment, the first method decreases the height of quadrant glitch to 0.5 nm by 5 times repetitive compensations. The second method also decrease the height of quadrant glitches to 2 nm, and the third method also can decrease the height to 0,5 nm with repetitive compensation at first time. It is confirmed that the nano-order contouring accuracy can be achieved by combination of the eight grooved linear ball guide and quadrant glitch compensations.

DOI： 10.2493/jjspe.84.925

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Language：Japanese   Publisher：Proceedings of 2018 ISFA - 2018 International Symposium on Flexible Automation  

An automatic process planning system for end-milling operation is proposed, in which CAM operator's intention for process planning is considered. In the previous process planning systems, the machining sequence is calculated geometrically. However, it remains difficult to determine the best machining sequence from the large number candidates of the calculated machining sequences. The previous process planning systems also do not consider CAM operator's intention in the determination of the appropriate machining sequence. First, our new process planning system stores the priority of machining features to be machined and the geometrical properties of the selected machining region from operations of CAM operators to decide the machining sequence. After storing the priority of machining feature and the geometrical properties, the appropriate machining sequence can be automatically determined by reflecting these information. CAM operator's intention, which is involved implicitly in the stored geometrical properties of the machining region, can be applied to decide the appropriate machining sequence.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

© Copyright 2018 ASME. Motion accuracy of NC machine tools is directory copied onto the machined shape. However, it is known that the motion accuracy is deteriorated by several error courses; geometric and dynamic motion errors of feed axes. In this study, in order to enhance the motion accuracy of NC machine tools, a method that modifies the NC program based on the normal direction error at each command point on the designed path is developed. In the method, the error vector between the commanded and estimated machined shape is obtained. The NC program for the motion is modified by adding the obtained error vector with the opposite sign. In order to confirm the effectiveness of the proposed method, 5-axis motion tests for cone-frustum cutting which is widely applied to the accuracy evaluation of 5-axis machining centers are carried out. At the first, it is confirmed that the proposed method can compensate the dynamic synchronous errors based on the feedback positions and angles of the axes. In addition, it is also confirmed that the proposed method can compensate both of dynamic and geometric errors based on the tool center point trajectory measured by a ball-bar system. As the results, it is clarified that the proposed method can effectively enhance the motion accuracy of the 5-axis machining center.

DOI： 10.1115/MSEC2018-6557

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© 2018 The Authors. Published by Elsevier Ltd. In this study, a novel end milling operation cutting simulator that considers the static tool deflection was developed. This simulator is based on an instantaneous rigid force model. In this model, the uncut chip thickness, which is necessary to estimate the cutting force, is calculated based on the static tool deflection, which consists of the deflections of the tool and tool holder caused by the cutting force. The newly developed end milling simulator represents the workpiece using a voxel model and calculates the uncut chip thickness from the removed voxels, which are those penetrated by the tool cutting edges. First, a previously developed method of calculating the uncut chip thickness from the voxels removed at minute tool rotation angle intervals was improved. Through the implementation of this improvement, cutting simulation with a high temporal resolution can be realized. With the proposed method, the cutting force is calculated from the uncut chip thickness at minute time intervals, and the static tool deflection is calculated from the cutting force. The uncut chip thickness is influenced by the static tool deflection. Therefore, the cutting force is calculated by considering the change in the uncut chip thickness due to the static tool deflection at minute time intervals. To confirm the effectiveness of the newly improved cutting simulator, a cutting experiment was conducted. The finished surface profiles estimated using the proposed method showed good agreement with the measured profiles.

DOI： 10.1016/j.procir.2018.08.218

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Language：Japanese   Publishing type：Research paper (international conference proceedings)   Publisher：The Japan Society of Mechanical Engineers  

Copyright © 2018 by ISFA. An automatic process planning system for end-milling operation is proposed, in which CAM operator's intention for process planning is considered. In the previous process planning systems, the machining sequence is calculated geometrically. However, it remains difficult to determine the best machining sequence from the large number candidates of the calculated machining sequences. The previous process planning systems also do not consider CAM operator's intention in the determination of the appropriate machining sequence. First, our new process planning system stores the priority of machining features to be machined and the geometrical properties of the selected machining region from operations of CAM operators to decide the machining sequence. After storing the priority of machining feature and the geometrical properties, the appropriate machining sequence can be automatically determined by reflecting these information. CAM operator's intention, which is involved implicitly in the stored geometrical properties of the machining region, can be applied to decide the appropriate machining sequence.

DOI： 10.1299/transjsme.17-00563

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Language：Japanese   Publisher：Proceedings of 2018 ISFA - 2018 International Symposium on Flexible Automation  

On-machine-Measurement (OMM) is the measuring on the machine tool and getting the result of machining instead of measuring on a measuring instrument. OMM doesn’t require the desperation and repositioning process, so the shortening the lead time for inspections is achieved. For execution of OMM the operator should set measurement strategy, such as measurement item, the number of measuring points and the position, to generate a NC program for the measurement. In this study, our aim is the automation of those preparation tasks required time and effort, especially touch trigger probe which is introduced for NC machine tools is utilized. Our proposed system automatically recognize the machining feature from the Total Removal Volume (TRV) detected between the CAD models of product and material, and decide the measuring strategy. Therefore, the NC program for executing OMM with touch trigger probe is automatically generated. A case study was conducted to show the effectiveness of the developed OMM system.

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Publishing type：Research paper (international conference proceedings)  

Copyright © 2018 by ISFA. On-machine-Measurement (OMM) is the measuring on the machine tool and getting the result of machining instead of measuring on a measuring instrument. OMM doesn’t require the desperation and repositioning process, so the shortening the lead time for inspections is achieved. For execution of OMM the operator should set measurement strategy, such as measurement item, the number of measuring points and the position, to generate a NC program for the measurement. In this study, our aim is the automation of those preparation tasks required time and effort, especially touch trigger probe which is introduced for NC machine tools is utilized. Our proposed system automatically recognize the machining feature from the Total Removal Volume (TRV) detected between the CAD models of product and material, and decide the measuring strategy. Therefore, the NC program for executing OMM with touch trigger probe is automatically generated. A case study was conducted to show the effectiveness of the developed OMM system.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Fuji Techno Press  

© 2018, Fuji Technology Press. All rights reserved. This study proposes an identification and compensation method for the geometric errors of the rotary axes in five-axis machining centers, based on the on-machine measurement results of the machined workpiece. Geometric errors can be identified from the shape geometry of the workpiece machined by five-axis motions because the influence of the errors appears on the shape geometry. An observation equation can be obtained based on the geometric error model and machined shape. The actual geometric errors can be identified by the least square matching of the measured and simulated machined shapes. In order to confirm the effectiveness of the proposed method, an actual cutting test and a simulation are performed. Based on their results, it is confirmed that the proposed method can successfully identify the geometric errors in the simulation. However, these errors cannot be identified in the experiments because a few of them do not have sufficient influences onto the machined shape. On the other hand, although the geometric errors cannot be correctly identified, it is confirmed that the they can be adequately compensated for based on the identified errors in both the simulation and experiment.

DOI： 10.20965/ijat.2018.p0230

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© Copyright 2018 ASME. S-shaped machining test is proposed for ISO standard to evaluate the motion accuracy of five-axis machining centers. However, it have not been investigated that which factor mainly influences the quality of the finished S-shape workpieces. This study focuses on the influence of the quality of NC program and geometric errors of rotary axes onto the quality of finished surface. Actual cutting tests and simulations are carried out to the investigation. As the results, it is clarified that the tolerance of NC program has a great influence onto the quality. It is also clarified that the geometric errors have great influences onto the quality. However, it is difficult to evaluate the influence of each geometric error because all geometric errors make glitches at the same point on the machined surface. It can be concluded that the proposed S-shape machining test can be used as the total demonstration of the machining techniques.

DOI： 10.1115/MSEC2018-6517

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

© 2018 The Japan Society of Mechanical Engineers. This paper describes the effects of preloading and ball retainer conditions of linear ball guides on a feed-drive system operating on a microscopic scale, as this is important for applications that employ linear guides in precision machines. To begin, relationships between nonlinear spring behaviors of the guide and the behavior of quadrant glitches were analyzed based on the proposed simple friction model. The behavior of the quadrant glitches, nanometer step responses, and steady vibrations were also measured for three guide conditions that differed with respect to the ball retainers and preloading. These experiments were carried out by using a special feed-drive system that comprises eight-grooved linear ball guides, an AC linear servo motor, and a linear encoder with a high position resolution of 31.25 pm. This system was set on a vibration isolation table and driven by a linear current amplifier. The time constants of each of the step responses were also analyzed based on the friction and control system model. From the analysis and experiments, it is demonstrated that the behavior of quadrant glitches and step responses are strongly influenced by the friction characteristics of the guides, and that this behavior can be adequately estimated via analysis. Additionally, it is shown that steady vibrations are also influenced by the friction characteristics, and that the amplitude of the vibration is proportional to the compliance of the nonlinear spring behavior.

DOI： 10.1299/jamdsm.2018jamdsm0099

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Language：Japanese   Publisher：Proceedings of 2018 ISFA - 2018 International Symposium on Flexible Automation  

It is expected that the S-shape machining test which has proposed to ISO standard can be an effective method of accuracy evaluation for five-axis machining centers. However, there are few research works done for the dynamic error influence on the S-shape machining accuracy. This study investigates the influences of federate, control mode of NC controller and position loop gain of feed drive systems of a five-axis machining center. Actual S-shaped machining motions are carried out to this investigation. As the result, the effect caused by feed rate and machine control function is clarified. Combination of the control mode and position loop gain significantly influence the S-shape machining accuracy. It can be concluded that the proposed S-shape machining test could be used to evaluate the total performance including the control mode of the five-axis machining centers.

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Publishing type：Research paper (international conference proceedings)  

Copyright © 2018 by ISFA It is expected that the S-shape machining test which has proposed to ISO standard can be an effective method of accuracy evaluation for five-axis machining centers. However, there are few research works done for the dynamic error influence on the S-shape machining accuracy. This study investigates the influences of federate, control mode of NC controller and position loop gain of feed drive systems of a five-axis machining center. Actual S-shaped machining motions are carried out to this investigation. As the result, the effect caused by feed rate and machine control function is clarified. Combination of the control mode and position loop gain significantly influence the S-shape machining accuracy. It can be concluded that the proposed S-shape machining test could be used to evaluate the total performance including the control mode of the five-axis machining centers.

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Copyright © 2018 by ISFA S-shaped test piece has been proposed by China as a method to evaluate the finishing accuracy of 5-axis machining center. In this test, machining accuracy of a 5-axis machining center is evaluated by measuring the shape error of a workpiece machined by 5-axis simultaneous control of an inclined S-shaped part with a flat end mill. In this report, among the series of draft standards proposed by China, the method given in September 2016 which is the newest executable one is examined using a medium-size vertical 5-axis machining center and checked its validity.

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>This study aims to develop a monitoring system, which can automatically detect tool wear in end-milling operation. A feature of this system is the utilization of the predicted cutting torque for detecting the difference between normal and cutting trouble. The cutting torque predicted by a cutting force simulator is compared with the cutting torque measured and evaluated from the driving torque of a spindle motor. Because the dynamic change of the cutting torque can be predicted by the cutting force simulator as the reference cutting torque, it is possible to detect cutting trouble correctly without disturbance arise from the changes of the cutting conditions and the machining form at every moment. In the cutting simulator, this study uses the workpiece voxel model in order to calculate the uncut chip thickness for the estimation of the cutting force. For the tool wear detection, 200 % increase of the average cutting torque is set as the threshold to detect 300 μm flank wear. In an experimental milling of a workpiece with holes using a worn square end mill, it is confirmed that the increase of the average cutting torque can be identified clearly in both of stationary and transient milling situations. It was verified that the tool flank wear could be detected correctly even in the dynamic change of milling operation.</p>

DOI： 10.1299/transjsme.17-00433

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>In order to achieve both high precision and high productivity in machining operation, machining error compensation of finished shape named as correction machining is more effective. In general, the correction machining requires additional CAD/CAM operations to generate the NC program for the correction machining, and it takes lots of time and effort. Hence, elimination of additional CAD/CAM operations for the correction machining is effective to reduce time and effort for correction machining. In this study, it is realized by integrating a newly developed On-Machine Measurement (OMM) system using a laser displacement sensor into the Digital Copy Milling (DCM) system. The DCM system was developed in our previous studies and achieves elimination of CAM operation for machining operations like a 3D printer. The OMM system can generate measurement paths automatically from a CAD model of the part based on copying principle. Tracing and measuring accuracy verified by experimental measurement of a reference sphere. Subsequently, a modified surface model represented by 3D point group data for the correction machining is generated immediately from the measurement paths and the measured machining error. Finally, the correction machining is performed immediately based on the modified surface data by the DCM system without CAM operation to generate an NC program. The effectiveness of the correction machining is validated by comparison between the finished sphere surfaces generated by the conventional and the proposed methods.</p>

DOI： 10.1299/transjsme.18-00191

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society for Precision Engineering  

In end milling operations, undesired tool approach marks may occur due to the tool deflection by transient cutting force change in the tool approach motion. The tool approach marks have a particularly big influence on the machined surface quality in case of the smooth and continuous surfaces are highly required. Therefore, in this study, a method to reduce the tool approaching mark due to the tool deflection by cutting force in ball end-milling operation is proposed. The influence of the tool deflection onto the machined surface is investigated. Characteristics of the tool approach mark are investigated based on the measured machined surfaces profile. As a result, it is confirmed that the behavior of the tool approach mark can be evaluated by using the proposed machining test. It is also confirmed from the results that the tool approach mark is generated by the difference of tool deflection by changing the actual radial depth of cut during the tool approach motion, A method to reduce the tool approach marks by the tool motion paths with the offset between the retract and approach paths is adopted, and the equation of the offset for effective compensation is proposed. It is experimentally confirmed that the proposed method can effectively eliminate the tool approach marks on the finished surface.

DOI： 10.2493/jjspe.84.110

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© Copyright 2018 ASME. A new method, which accurately predicts cutting force in ball end milling considering cutting edge around center web, has been proposed. The new method accurately calculates the uncut chip thickness, which is required to estimate the cutting force by the instantaneous rigid force model. In the instantaneous rigid force model, the uncut chip thickness is generally calculated on the cutting edge in each minute disk element piled up along the tool axis. However, the orientation of tool cutting edge of ball end mill is different from that of square end mill. Therefore, for the ball end mill, the uncut chip thickness cannot be calculated accurately in the minute disk element, especially around the center web. Then, this study proposes a method to calculate the uncut chip thickness along the vector connecting the center of the ball and the cutting edge. The proposed method can reduce the estimation error of the uncut chip thickness especially around the center web compared with the previous method. Our study also realizes to calculate the uncut chip thickness discretely by using voxel model and detecting the removal voxels in each minute tool rotation angle, in which the relative relationship between a cutting edge and a workpiece, which changes dynamically during tool rotation. A cutting experiment with the ball end mill was conducted in order to validate the proposed method. The results showed that the error between the measured and predicted cutting forces can be reduced by the proposed method compared with the previous method.

DOI： 10.1115/MSEC2018-6564

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© 2018 The Authors. Published by Elsevier Ltd. In this study, a virtual milling force monitoring method is proposed for industrial milling process monitoring. For this purpose, a modified instantaneous rigid force model is proposed. Oblique and orthogonal cutting theories are applied in the model to reduce the number of cutting parameters required for milling force prediction. Only the shear angle must be determined in advance for cutting force prediction. In practice, the shear angle can be determined immediately at the start of a milling operation. Based on the shear angle, the milling forces are predicted and can be used instead of the measured milling forces. In addition, in the proposed force model, runout is taken as the difference in the uncut chip thickness between cutting edges. In order to confirm the effectiveness of the proposed force model, a milling experiment was conducted. The predicted milling forces were found to be in agreement with the measured values. These results demonstrate that milling process monitoring can be achieved without conducting experimental milling to determine the required parameters for prediction or installing additional force sensors.

DOI： 10.1016/j.procir.2018.08.196

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Language：Japanese   Publisher：Proceedings of 2018 ISFA - 2018 International Symposium on Flexible Automation  

S-shaped test piece has been proposed by China as a method to evaluate the finishing accuracy of 5-axis machining center. In this test, machining accuracy of a 5-axis machining center is evaluated by measuring the shape error of a workpiece machined by 5-axis simultaneous control of an inclined S-shaped part with a flat end mill. In this report, among the series of draft standards proposed by China, the method given in September 2016 which is the newest executable one is examined using a medium-size vertical 5-axis machining center and checked its validity.

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Language：Japanese   Publisher：Society of Automotive Engineers of Japan  

A new cutting force simulator, which calculates discretely uncut chip thickness based on fully voxel representation of cutting edge and instantaneous workpiece shape, has been developed to predict cutting force for corner radius end mill. In this cutting force simulator, it is possible to detect the uncut chip thickness between the complex workpiece shape and the special cutting edge shape such as corner radius end mill. Experimental milling tests using a corner radius end mill were conducted for the verification of this cutting force simulation. Predicted milling forces have good agreement with measured milling forces.

DOI： 10.11351/jsaeronbun.49.107

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DOI： 10.115/1.4038499

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Language：Japanese   Publisher：Proceedings of the 9th International Conference on Leading Edge Manufacturing in 21st Century, LEM 2017  

An important facet of the contouring performance of machine tools with computer numerical control (CNC) is the machining of workpieces within the desired accuracy and within as short a time as possible. However, conventionally, the accuracy (error) and the speed are evaluated separately. Therefore, in this research, a method is proposed to evaluate the speed and accuracy of CNC machine tools using two-dimensional expressions of error and speed based on actual trajectories. Experiments have verified that it is possible to quantitatively evaluate the speed and accuracy of multiple CNC machine tools using two-dimensional graphs of maximum error and actual speed.

DOI： 10.1299/jsmelem.2017.9.034

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

The purpose of this study is to propose a revised instantaneous rigid force model based on oblique cutting model for end-milling operation to eliminate predetermination of cutting coefficients. Although, six cutting coefficients are required for cutting force prediction in the conventional instantaneous rigid force model, the shear angle is only required in our revised force model. The determination of the shear angle is easier than the determination of six cutting coefficients from the cutting test. As a result from a validation, our revised force model can predict the cutting force more practically than the conventional instantaneous rigid force model.

DOI： 10.1299/jsmelem.2017.9.060

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It is known that in multi-axis simultaneous control machining of complicated shape parts, machining accuracy may decrease due to synchronous error of the drive axes, and machining time may be longer due to excessive acceleration. In this study, in the machining using 5-axis control machining centers, in order to investigate the difference in machining accuracy and machining time depending on the number of drive axes simultaneously controlled, 4-axis and 5-axis simultaneous machining of a complex shaped blade are compared as a case study. As a result, it is found that the machining accuracy is better in the 5-axis simultaneous machining, but the machining time is shorter in the 4-axis simultaneous machining.

DOI： 10.1299/jsmelem.2017.9.098

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

In this study, a new method utilizing the similarity of removal volume to select the most similar machining case data is proposed to realize automated NC program generation. The geometric information of the removal volume, which is extracted by splitting total removal volume, and the cutting conditions associated with the removal volume are stored in database as a machining case data. The proposed method can select the most similar machining case data from database even for the complicated product shape, because each extracted removal volume is geometrically simple. In the case study for the validation of the proposed method, the cutting conditions were successfully determined from the most similar machining case data and an NC program was automatically generated appropriately.

DOI： 10.1299/jsmelem.2017.9.055

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

Since cutting force acts on feed drive and spindle drive systems as force disturbance, feed speed and spindle speed are changed. As the results, cutting force is also changed. In this study, a coupled simulation method of the vibration of machine tool, the dynamic behaviors of feed and spindle drive systems and the cutting force is developed. Simulation results are compared with the experimental results, and it is confirmed that the vibration of the feed and spindle drive systems due to the cutting force can be simulated by the proposed method. It is also confirmed that the cutting force influenced by the vibrations can be expressed.

DOI： 10.1299/jsmelem.2017.9.044

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

This paper describes influence of preload and retainer of linear ball guides on feed drive system in microscopic region which become important when the linear guides are used in precision machines. At first, relationships between nonlinear-spring-behaviors of the guide and behavior of quadrant glitches are analyzed based on proposed friction model. Behavior of the quadrant glitches, nanometer step responses and steady vibrations are also measured with the three different guide conditions; with/without ball retainers and preload changes. Time constant of the step responses are also analyzed based on the friction and control system model. From the analysis and experiments, it is clarified that the behavior of quadrant glitches and step responses are strongly influenced by the friction characteristics of the guides, and the behavior can adequately be estimated by the analysis. It is also clarified that the steady vibrations are also influenced by the friction characteristics, the amplitude of the vibration is proportional to the compliances of the nonlinear-spring-behavior.

DOI： 10.1299/jsmelem.2017.9.030

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：Fuji Techno Press  

It is known that the machined shape errors occurred in the NC machine tools can be compensated by modifying the CL-data based on amount of the errors calculated by measurement results of workpiece shape. By this method, however, the shape errors cannot be compensate accurately in case of 5-axis machining, because the final machining shape may not a copy of motion trajectory of tool functional point due to the motion errors of translational and rotary axes. In this study, a modification method of CL-data which based on the amount of motion errors of tool center point trajectory during the machining motion is newly proposed. Simulation and experiment of wing profile machining motion is carried out to confirm the effectiveness of the proposed method. As the result, it is confirmed that the motion accuracy can significantly be improved by applying the proposed method.

DOI： 10.1299/jsmelem.2017.9.045

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

In this study, position and angle commands of each axis when machining the same blade shape with a 5 - axis machining center with different NC were recorded and the influence of NC type and control function on cycle time and velocity fluctuation was investigated. As a result, it was found that the cycle time is greatly shortened by using tool tip point control. In addition, the relative velocity is influenced on NC controller, acceleration or jerk is limited.

DOI： 10.1299/jsmelem.2017.9.097

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

The purpose of this study is to clarify the influence of the torsional damping and the lead of ball-screw onto the vibration characteristic of the feed drive system. In this study, the measurement tests are carried out with a feed drive system consisting of an AC servo motor, a coupling, a ball-screw, and linear ball guides. It is clarified from the experiments that the feed drive system has three main vibration modes. It is also confirmed that the second vibration mode can directory be influenced by the torsional damping of the coupling, and smaller lead of ball-screw makes higher amplitude of the second vibration mode and lower amplitude of the first vibration mode.

DOI： 10.1299/jsmelem.2017.9.043

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

In this study, a method to reduce the tool approach mark due to the tool deflection by cutting force in ball end-milling operation is proposed. In order to reduce the approach marks, the influence of the tool deflection onto the machined surface is investigated. Characteristics of the tool approach mark are investigated based on the measured machined surfaces by a roughness tester. On the investigation, it is confirmed that the tool approach mark exists caused by the tool deflection and the tool deflection is copied onto the surface. A compensation method to reduce the tool approach mark by changing approaching point is proposed. It is also confirmed that the influence of the tool approach mark can be reduced by the proposed tool approach path offset.

DOI： 10.1299/jsmelem.2017.9.015

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Language：Japanese   Publishing type：Research paper (international conference proceedings)  

The purpose of this study is to develop a novel mechanical vibration suppression method for high speed tracking motions. In this study, the mechanical vibration suppression method by applying vibration compensation torque to cancel the mechanical vibration during high speed tracking motions is proposed. In order to evaluate the effectiveness of the proposed method, rectangular corner tracking motions with applying the compensation torque are measured and simulated. As the results, it is confirmed that the proposed method can effectively suppress the vibration when the motion direction changes. It is also clarified that proposed method can effectively works for various feed speed by automatically adapting the torque based on the proposed criteria.

DOI： 10.1299/jsmelem.2017.9.042

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE INC  

© 2017 Elsevier Inc. The method of evaluating two-dimensional contouring error between the reference trajectory and the trajectory measured with a cross-grid encoder and magnifying the error is widely used. However, this method has a problem in that the inner cornering error is discontinuously magnified and represented and thus is not accurately detected. Several methods have been proposed to solve this problem, but they have limitations, such as the requirement that an offset value be set or the imposition of conditions on the reference trajectory. Therefore, by calculating errors in the inward direction from a longer trajectory to a shorter trajectory, this paper proposes a new method to continuously magnify and represent the inner cornering error including the corner vertex without the need to set an offset or the imposition of conditions on the reference trajectory. The proposed method was applied to the measurement results at an actual machining center. Consequently, the inner cornering error was continuously magnified and represented, and the error at a corner was accurately calculated using the proposed method.

DOI： 10.1016/j.precisioneng.2017.06.018

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Fuji Technopress  

© 2017, Fuji Technology Press. All Rights Reserved. Several methods for evaluating the motion accuracy of the rotary axes in five-axis machining centers have been proposed till date. As it is known that particular motion errors exist around the motion direction changing points, it is important to evaluate the behavior of the rotary axes around these points. However, the influence of the motion error in the translational axes is included in the conventional evaluation results, as the translational axes reverse at the motion direction changing points about the rotary axes. In this study, an evaluation method which can assess the behavior of a rotary axis around motion direction changes by synchronous motion of translational and rotary axes is proposed. In this method, the direction of translational axes does not change when the motion direction of a rotary axis changes. A measurement test and actual cutting tests are carried out to clarify the influence of the behaviors of rotary axes on the motion trajectory and machined surface, caused by the change in the motion direction of the rotary axis. Simulations of the motion are also carried out to discuss the causes of inaccuracy.

DOI： 10.20965/ijat.2017.p0171

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society for Precision Engineering  

Several methods for evaluating the motion accuracy of the rotary axes of five-axis controlled machining centers have been proposed up to now. Since it is known that particular motion errors exist around motion direction changing points, it is important to evaluate the behavior of the rotary axes around these points. In this study, the characteristic of axial displacement around the motion direction changing point of the rotary axis in a five-axis controlled machining center and the influence of this characteristic onto the machined surface are investigated. The dynamic behavior around the motion direction changing point of the rotary axis was measured by the eddy current type displacement sensor. And the axial displacement of the rotary axis was investigated from the measured results. A machining test to evaluate the influence of the axial displacement of the rotary axis on machining surface is also proposed. It is confirmed from the results that the axial displacement of the rotary axis exists caused by the rotational direction change and it has an influence to the machining surface. In addition, it is confirmed that the influence of the axial displacement of the rotary axis can be compensated by translational displacement of linear axis.

DOI： 10.2493/jjspe.83.893

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society for Precision Engineering  

This paper experimentally and theoretically investigates the relationship between the nonlinear spring behavior (NSB) of linear ball guide and the quadrant glitch in microscopic circular motions, A high precision stage which has nanometer resolution consists of eight grooved linear ball guides and a linear motor is developed for the experiments. Microscopic circular motion tests are carried out to investigate the quadrant glitches in the region. The experimental results suggest that the shape of the quadrant glitches depend on the radius of the circle. It is also suggested that the height of quadrant glitches depend on the frequency of the motion. Relationship between the shape and height of quadrant glitches and NSB of the linear ball guides has theoretically analyzed based on the simplified NSB model. The theoretical model can adequately explain the actual behaviors. Influence of the ball retainer and preload conditions on the NSB are also investigated. It is confirmed that the ball retainers significantly influences the NSB.

DOI： 10.2493/jjspe.83.796

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER SOC MECHANICAL ENGINEERS  

© Copyright 2017 ASME. A new cutting force simulator has been developed to predict cutting force in ball end milling. This new simulator discretely calculates uncut chip thickness based on a fully voxel representation of the cutting edge and instantaneous workpiece shape. Previously, a workpiece voxel model was used to calculate uncut chip thickness under a complex change of workpiece shape. Using a workpiece voxel model, uncut chip thickness is detected by extracting the voxels removed per cutting edge tooth for the amount of material fed into the cutting edge. However, it is difficult to define the complicated shape of a cutting edge using the workpiece voxel model; the shape of the cutting edge must be defined by a mathematical expression. It is also difficult to model the voxels removed by the cutting edge when the tool posture is non-uniformly changed. We therefore propose a new method to detect uncut chip thickness, one in which both the cutting edge and the instantaneous workpiece shape are fully represented by a voxel model. Our proposed method precisely detects uncut chip thickness at minute tool rotational angles, making it possible to detect the uncut chip thickness between the complex surface shape of the workpiece and the particular shape of the cutting edge. To validate the effectiveness of our proposed method, experimental 5-axis milling tests using a ball end mill were conducted. Estimated milling forces for several tool postures were found to be in good agreement with the measured milling forces. Results from the experimental 5-axis milling validate the effectiveness of our proposed method.

DOI： 10.1115/MSEC2017-2777

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER SOC MECHANICAL ENGINEERS  

© Copyright 2017 ASME. Energy consumption of numerical control (NC) machine tools is one of the key issues in modern industrial field. This study focuses on reducing the energy consumed by a five-axis machining center by changing only the workpiece-setting position. Previous studies show that the movements along each axis in five-axis machining centers depend on the workpiece-setting position, regardless of whether the same operation is performed. In addition, the energy consumptions required for the movements are different along each axis. From these considerations, an optimum workpiece-setting position that can minimize the energy consumed during these motions is assumed to exist. To verify this assumption, in this study, the energy consumed by the feed drive systems of an actual five-axis machining center is first measured and then estimated using the proposed model in this study. The model for estimating the energy consumption comprises the friction, motor, and amplifier losses along each axis. The total energy consumption can be estimated by adding the energy consumptions along each axis. The effect of the workpiece setting-position on the energy consumption is investigated by employing the cone-frustum cutting motion with simultaneous five-axis motions. The energy consumption that depends on the workpiece-setting position is first measured and then estimated. The results confirm that the proposed model can estimate the energy consumption accurately. Moreover, the energy consumption is confirmed to depend on the workpiece-setting position; the minimum energy consumption is found to be 20% lower than the maximum one.

DOI： 10.1115/MSEC2017-2711

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DOI： 10.2493/jjspe.83.204

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER SOC MECHANICAL ENGINEERS  

© Copyright 2017 ASME. In this study, we propose a new process planning system for machining operations, one which considers user strategies and intentions for such operations. In previous process planning systems, the machining sequence is calculated geometrically, based on the Total Removal Volume (TRV) and the machining primitive region split from TRV. However, it remains difficult to determine the best machining sequence from among the large number of machining sequences calculated. Also, previous process planning systems do not consider user strategies and intentions in determining the appropriate machining sequence. Our new approach stores geometrical properties of the machining primitives when the user selects a machining sequence. Using these stored geometrical properties, the appropriate machining sequence can be automatically selected. User strategies and intentions are thus considered in determining a machining sequence based on learned geometrical properties. A case study was conducted to show the effectiveness of our proposed process planning approach. In the case study, user-specific machining sequences were automatically determined for various users, based on the relation among the geometrical properties of the machining primitives and the individual user's strategies and intentions.

DOI： 10.1115/MSEC2017-2749

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>In end milling, in order to improve machining efficiency and accuracy, instantaneous rigid force model is widely used to predict cutting force and improve cutting conditions. The instantaneous rigid force model is well known as the practically simple model to predict cutting force. However this model requires the six parameters called cutting coefficients which have to be determined by the experimental milling operation. So several experimental milling operations are needed before cutting force prediction. In this study, a new instantaneous rigid force model based on oblique cutting is proposed. In this force model, the end milling process is modeled using the oblique cutting model. Therefore, cutting force prediction can be realized using only the one parameter such as shear angle instead of the six parameters such as cutting coefficients required for a conventional instantaneous rigid force model. The shear angle can be determined from tangential milling force or milling torque. And this force model is easier to apply for practical cutting force prediction, because time and effort to determine the parameter(s) before cutting force prediction. The validation of this force model compared with the conventional force model is performed. As the result, cutting forces predicted by the proposed force model has good agreement with the measured cutting forces. Also, the proposed force model has good performance in a wide range of cutting conditions compared with the conventional force model.</p>

DOI： 10.1299/transjsme.17-00247

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

<p>It is known that the cutting force excites the structural vibration of machine tool. In addition, cutting force acts on feed and spindle drive system as a force disturbance, and feed speed and spindle speed are changed. As the results, cutting force is also changed because the depth of cut and cutting speed are changed due to the machine vibration, feed and spindle speed changes. The purpose of this study is to analyze the coupled vibration between the machine tool behavior and the cutting force. In order to achieve the purpose, in this study, a coupled simulation method of the vibration of machine tool, the dynamic behaviors of feed and spindle drive systems and the cutting force is developed. Cutting force and machined surface geometry is simulated using the voxel simulator in which the workpieces is represented by voxels. Undeformed chip thickness can be calculated based on the relative position between the tool and workpieces, and the tool rotational angle at the each time step based on the voxel model. The cutting force is estimated based on the calculated undeformed chip thickness. The relative position between tool and workpiece at each time step is simulated by the feed drive system and machine tool structural models. The tool rotational angle is simulated by the spindle drive system model. The coupled simulation between the cutting force, structural vibration of machine tool and feed and spindle drive systems is carried out by applying the simulated cutting force and cutting torque as a disturbance to the feed and spindle drive systems and machine tool structure. Cutting tests and simulations are carried out with two kinds of radial depth of cut, 5 mm and 20 mm. It is confirmed that the machine tool dynamic behaviors due to the cutting force and torque which is also influenced by the machine tool behaviors can be simulated by the proposed method. It is also confirmed that the chatter vibration which is observed in case of the 20 mm depth of cut can be simulated by the proposed method.</p>

DOI： 10.1299/transjsme.17-00254

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Language：Japanese   Publisher：THE INSTITUTE OF SYSTEMS, CONTROL AND INFORMATION ENGINEERS (ISCIE)  

<p>A new method of the process planning for end-milling operation considering product design constraints in this study. In our previous study, the process planning system, in which the Total Removal Volume is divided by the planes parallel with the XY, YZ or ZX planes to analyze machining sequence from top to bottom of the target product, is proposed. In this study, the process planning system, in which the Total Removal Volume is divided by all planes (including slope planes) existing on the target product, is proposed. Furthermore, the product design constraints or the designer's intention such as separate through holes which have the same central axis to be slide bearing is considered. A case study was conducted and the result showed that the proposed method can generate efficient multiple process plans for the machining operation. These multiple process plans or machining sequences are available to select adaptively the most suitable process plan or machining sequence under the several conditions such as the machine tool to be used and the product design constructions.</p>

DOI： 10.5687/iscie.30.81

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Language：Japanese   Publisher：Japanese Society for Engineering Education  

Synthetic design thinking is needed to create innovative products. We propose an educational method for creative design that can enhance a person&rsquo;s ability to generate a new products&rsquo; concept that are not extensions of existing ones. The method starts with a person coming up with a concept based on &lsquo;intuitive synthesis&rsquo; in which the metaphor of a &lsquo;product like a living thing&rsquo; is instinctively created; details are confirmed by &lsquo;analyzing and investigating&rsquo; the concept&rsquo; s characteristics, followed by an &lsquo;experience&rsquo; of the product and the scene in which it will be employed using a virtual reality device. Based on this method, a design engineering school was carried out. Students enthusiastically joined this program, and their outcomes were pioneering previously non-existent products.

DOI： 10.4307/jsee.65.5_59

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：DESIGN SOC  

In the modern era, what we produce is important, and synthetic design thinking is strongly needed to create innovative products that bring qualitative changes to users' lifestyles. This paper proposes an educational method for creative design that can enhance a person's ability to generate a new concept of ground-breaking products that are not merely extensions of existing ones. This approach is unique due to its process, which starts with a person coming up with a concept based on 'intuitive synthesis' in which the metaphor of a 'product like a living thing' is instinctively created; then, details are confirmed by 'analyzing and investigating' the concept's characteristics, followed by a 'representation' of the product and the scene in which it will be employed using a virtual reality device. Based on this educational method, the International Design Engineering School was carried out in 2016. Students enthusiastically joined this program, and their design outcomes were found not to be improvements of existing products, but rather, were pioneering previously non-existent products.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

© 2016 IEEE. This study proposes the method of the process planning for 5-axis machine tools. In our previous study, the process planning, in which the Total Removal Volume is divided by the planes parallel with the XY, YZ or ZX plane to analyze machining sequence from top to bottom of the target product, is proposed. In this study, the process planning system in which the Total Removal Volume is divided by all planes (including slope planes) existing on the target product is proposed. Furthermore, the design constraint or the designer's intention such as discontinuous through holes which have the same central axis is considered in this process planning. A case study was conducted and the result showed that the proposed method can design efficient multiple process plans for the machining operation. These multiple process plans or machining sequences allow users to select adaptively the suitable process plan or machining sequence based on the property of 5-axis machine tool to be used under the design constraint.

DOI： 10.1109/ISFA.2016.7790187

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

© 2016 IEEE. In the machining of molds and dies, it is quite important that the finished surface have no visible glitches. The purpose of this study is to develop the evaluation method for finished surface based on the human visual characteristic. In order to achieve the purpose, visual resolution and recognition limit of normal vector changes of the machined shape are investigated. The visual resolution of the human eyes is evaluated based on tool marks on the machined surface. The recognition limit of normal vector changes is evaluated based on the workpiece which has normal vector changes in its shape or surface profile. An evaluation method for the finished surface is proposed based on the investigated characteristics. In order to confirm the usability of the proposed method, evaluation tests of actual machined surfaces influenced by the machine tool motion errors are carried out. As the results, it is clarified that the proposed method can accurately evaluate visibility of the glitches on the machined surface.

DOI： 10.1109/ISFA.2016.7790201

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

© 2016 IEEE. Although the motion error around motion direction changing points of each axis affects the accuracy of machined parts, evaluation and compensation methods for the dynamic behavior around motion direction changes of rotary axis has not been established up to now. In this study, an evaluation method which can evaluate the behavior of rotary axis around motion direction changes by synchronous motion of translational and rotary axes is proposed. In the method, direction of translational axes does not change when the motion direction of a rotary axis changes. Measurement test and actual cutting tests are carried out in order to clarify the influence of the behaviors onto the motion trajectory and machined surface quality, caused by the motion direction changing of the rotary axis. Simulations of the motion are also carried out to discuss the causes of inaccuracy.

DOI： 10.1109/ISFA.2016.7790185

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society for Precision Engineering  

A new cutting force simulator which calculates discretely uncut chip thickness by referring workpiece voxel model has been developed to predict cutting force in end-milling operation. This cutting force simulator can predict cutting force under the complex change of workpiece shape and the non-uniform contact between cutting edge and workpiece. Additionally, a new methodology to realize adaptive control or feed speed control based on the predicted cutting force is developed by integrating with the digital copy milling system which can generate tool paths in real-time during machining operation. This methodology can revise the tool feed speed based on the cutting force which predicted simultaneously with the real end-milling operation.

DOI： 10.2493/jjspe.82.467

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society for Precision Engineering  

The motion accuracy of 5-axis controlled machining centers typically is inferior to the accuracy of 3-axis controlled machining centers. Especially, the motion error of rotary axis by motion direction changes in particular has bad influence to machined surfaces in comparison with the motion error of translational axis, because it is amplified by the distance from the center of the rotary axis to the machining point. In this study, a measurement system and a machining test method arc proposed to evaluate the dynamic characteristics of rotary axis by motion direction changes, and the compensation method is considered. It is confirmed by the measuring system and the machining tests that the influence of tracking error on the machined surface is related with the size/shape of the tools and geometrical relationships between the tracking error and the machined surface. In addition, the method to improve the machining accuracy by the dynamic characteristics of rotary axis around the motion direction changing point is proposed, and the effect is confirmed by the actual machining tests.

DOI： 10.2493/jjspe.82.913

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DOI： 10.1299/jamdsm.2016jamdsm0075

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Language：English   Publisher：The Japan Society of Mechanical Engineers  

<p>Several methods of evaluating the motion accuracy of the rotary axes of five-axis machining centers have been proposed in past studies. Because it is known that particular motion errors exist near motion direction changing points, it is important to evaluate the behavior of the rotary axes near these points. However, the influence of the motion error of the translational axes is included in conventional evaluation results because the translational axes reverse at the motion direction changing points about the rotary axes. In this study, a measurement system for evaluating the dynamic characteristics of the rotary axes near the motion direction changing points about these axes, excluding the influence of the translational axes, was developed. The measurement tests were also conducted using this measurement system for evaluating the dynamic characteristics of the tilt axis near the motion direction changing points about this axis. In addition, an actual machining test was conducted to evaluate the influence of the motion errors of the tilt axis near the motion direction changing points. As a result, it was confirmed that the behavior of the tilt axis near the motion direction changing points can be evaluated by using the proposed measurement method. It was also confirmed that the influence of the motion error on the machined surface is related to the size and shape of the tool and the geometric relationship between the motion error and the machined surface. It was also confirmed that the machined shape does not always contain defects when motion errors exist depending on the relationship between the motion error and the machined surface.</p>

DOI： 10.1299/jamdsm.2016jamdsm0075

CiNii Research

Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC MECHANICAL ENGINEERS  

Several methods of evaluating the motion accuracy of the rotary axes of five-axis machining centers have been proposed in past studies. Because it is known that particular motion errors exist near motion direction changing points, it is important to evaluate the behavior of the rotary axes near these points. However, the influence of the motion error of the translational axes is included in conventional evaluation results because the translational axes reverse at the motion direction changing points about the rotary axes. In this study, a measurement system for evaluating the dynamic characteristics of the rotary axes near the motion direction changing points about these axes, excluding the influence of the translational axes, was developed. The measurement tests were also conducted using this measurement system for evaluating the dynamic characteristics of the tilt axis near the motion direction changing points about this axis. In addition, an actual machining test was conducted to evaluate the influence of the motion errors of the tilt axis near the motion direction changing points. As a result, it was confirmed that the behavior of the tilt axis near the motion direction changing points can be evaluated by using the proposed measurement method. It was also confirmed that the influence of the motion error on the machined surface is related to the size and shape of the tool and the geometric relationship between the motion error and the machined surface. It was also confirmed that the machined shape does not always contain defects when motion errors exist depending on the relationship between the motion error and the machined surface.

DOI： 10.1299/jamdsm.2016jamdsm0075

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Language：Japanese   Publisher：Journal of Advanced Mechanical Design, Systems and Manufacturing  

Several methods of evaluating the motion accuracy of the rotary axes of five-axis machining centers have been proposed in past studies. Because it is known that particular motion errors exist near motion direction changing points, it is important to evaluate the behavior of the rotary axes near these points. However, the influence of the motion error of the translational axes is included in conventional evaluation results because the translational axes reverse at the motion direction changing points about the rotary axes. In this study, a measurement system for evaluating the dynamic characteristics of the rotary axes near the motion direction changing points about these axes, excluding the influence of the translational axes, was developed. The measurement tests were also conducted using this measurement system for evaluating the dynamic characteristics of the tilt axis near the motion direction changing points about this axis. In addition, an actual machining test was conducted to evaluate the influence of the motion errors of the tilt axis near the motion direction changing points. As a result, it was confirmed that the behavior of the tilt axis near the motion direction changing points can be evaluated by using the proposed measurement method. It was also confirmed that the influence of the motion error on the machined surface is related to the size and shape of the tool and the geometric relationship between the motion error and the machined surface. It was also confirmed that the machined shape does not always contain defects when motion errors exist depending on the relationship between the motion error and the machined surface.

DOI： 10.1299/jamdsm.2016jamdsm0075

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Fuji Technopress  

© 2016, Fuji Technology Press. All rights reserved. The purpose of this study is to develop a new machine bed support mechanism for reducing the vibration generated during the high-speed tracking motion of numerical control machine tools. In order to achieve this, the frequency response and motion trajectory of a machine tool with the proposed machine bed, which has a sliding surface, aremeasured and compared with that of the conventional support. Based on the modal analysis of the machine tool structure, a mathematical model representing the influence of the machine bed characteristics on the vibration is also developed. The model consists of a bed, saddle, table, column, and spindle head. Every component has three degrees of freedom for each of the translational and rotational axes. In order to evaluate the characteristics of the machine bed, the mathematical model determines the stiffness and damping along the X-, Y-, and Z-axis between the bed and the ground. The frequency response curves simulated by using the mathematicalmodel are compared with that of the measured ones. From the results of the experiments and simulations, it is confirmed that the vibration generated during high-speed tracking motions can be reduced by using the proposed machine bed with a sliding surface.

DOI： 10.20965/ijat.2016.p0447

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© 2015, Fuji Technology Press. All rights reserved. In this study, we have constructed a mathematical model that can analyze the coupled vibration of machine tool structure and feed drive systems. The model is proposed on the basis of themodal analysis of the actual machine tool structure. It consists of three translational and three rotational displacements of the bed, relative angular deformations between the bed and column, relative translational and angular deformations between the bed and saddle, and relative translational and angular deformations between the column and spindle head. In addition, each feed drive system is modeled using a vibration model, which has two degrees of freedom. The servo controllers of each axis are also modeled. To confirm the validity of the proposed model, frequency responses, motion trajectories of the feedback positions, linear scale positions, and the relative displacement between the table and head are measured and simulated. The effect of coupled vibrations on the tracking errors is examined with the help of both experiments and simulations. To investigate the effect of the servo systems on the vibration, both experiments and simulations are carried out by using feed drive systems in the following three conditions: mechanically clamped, servo-on, and servo-off. The results of experiments and the simulations show that the proposed model can express the mode of vibration and the influence of the condition of feed drive systems on the mode of vibration.

DOI： 10.20965/ijat.2015.p0689

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Language：Japanese   Publisher：Proceedings of the 8th International Conference on Leading Edge Manufacturing in 21st Century, LEM 2015  

Several methods to evaluate the motion accuracy of the rotary axis of 5-axis machining centers have been proposed and attracts attention. However, the influence by the translational axes is included in an evaluation result because the translational axes turn over at the motion direction changing point of the rotary axis in a general simultaneous motion of the rotary and translational axes. In this study, a measurement system to evaluate the dynamic characteristics of rotary axis around the motion direction changing point which can eliminate the influence of translational axes is developed. In addition, it is confirmed by the actual machining tests that the influence of tracking error on the machined surface is related with the size/shape of the tools and geometrical relationships between the tracking error and the machined surface.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：JAPAN SOC MECHANICAL ENGINEERS  

Several methods to evaluate the motion accuracy of the rotary axis of 5-axis machining centers have been proposed and attracts attention. However, the influence by the translational axes is included in an evaluation result because the translational axes turn over at the motion direction changing point of the rotary axis in a general simultaneous motion of the rotary and translational axes. In this study, a measurement system to evaluate the dynamic characteristics of rotary axis around the motion direction changing point which can eliminate the influence of translational axes is developed. In addition, it is confirmed by the actual machining tests that the influence of tracking error on the machined surface is related with the size/shape of the tools and geometrical relationships between the tracking error and the machined surface.

DOI： 10.1299/jamdsm.2016jamdsm0075

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In previous studies, a total removal volume (TRV) unit has been introduced and showed its advantages as the alternative of machining features (MF) in feature-based process planning system. The TRV constitutes a volume that needs to be removed in order to make the product shape. Since the estimation of TRV is based on the actual condition of the raw material, the variety of TRV's shapes are more than the traditional MF definition. Therefore, further machining process plan (MPP) which considers both roughing and finishing is needed. In this paper, a TRV-based generative machining process planning system is proposed. A consideration of the product's geometry and dimension tolerances (GDT) is used for representing both roughing and finishing process. This study is based on milling operation on prismatic shapes.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：JAPAN SOC MECHANICAL ENGINEERS  

Unexpected problems may occur on the finished surface machined by the 5-axis machining centers, because of geometric and dynamic synchronous errors of the machine. In this study, actual ball-end milling tests of hemispheres and its finished surface simulations considering the different geometric errors and different position loop gain of feed drive systems were carried out, in order to clarify the influence of the errors onto machined surface. As the results, it is clarified that the influence of geometric errors onto the machined surface is depending on the relationships between the movement of the axes and the surface geometry. In addition, the dynamic synchronous error also influences the machined surface when the velocity of translational and rotational axes changed rapidly.

DOI： 10.1299/jamdsm.2016jamdsm0071

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Language：Japanese   Publisher：Proceedings of the 8th International Conference on Leading Edge Manufacturing in 21st Century, LEM 2015  

Unexpected problems may occur on the finished surface machined by the 5-axis machining centers, because of geometric and dynamic synchronous errors of the machine. In this study, actual ball-end milling tests of hemispheres and its finished surface simulations considering the different geometric errors and different position loop gain of feed drive systems were carried out, in order to clarify the influence of the errors onto machined surface. As the results, it is clarified that the influence of geometric errors onto the machined surface is depending on the relationships between the movement of the axes and the surface geometry. In addition, the dynamic synchronous error also influences the machined surface when the velocity of translational and rotational axes changed rapidly.

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Language：Japanese   Publisher：Proceedings of the 8th International Conference on Leading Edge Manufacturing in 21st Century, LEM 2015  

In previous studies, a total removal volume (TRV) unit has been introduced and showed its advantages as the alternative of machining features (MF) in feature-based process planning system. The TRV constitutes a volume that needs to be removed in order to make the product shape. Since the estimation of TRV is based on the actual condition of the raw material, the variety of TRV's shapes are more than the traditional MF definition. Therefore, further machining process plan (MPP) which considers both roughing and finishing is needed. In this paper, a TRV-based generative machining process planning system is proposed. A consideration of the product's geometry and dimension tolerances (GDT) is used for representing both roughing and finishing process. This study is based on milling operation on prismatic shapes.

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Publishing type：Research paper (international conference proceedings)  

The purpose of this study is to develop the new machine bed support mechanism which can reduce the vibration generated in high speed tracking motion. In order to achieve the purpose, frequency response and motion trajectory are measured on the machine supported by the proposed machine bed support which has sliding surface, and compared with the results measured on the machine supported by the conventional one. A mathematical model that can represent the influence of the machine support characteristic is also developed. The simulated frequency responses are compared with the measured ones. As the results from the experiments and simulations, it is confirmed that the vibration generated in high speed tracking motion can be reduced by the proposed machine bed support which has sliding surface.

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Language：Japanese   Publisher：Proceedings of the 8th International Conference on Leading Edge Manufacturing in 21st Century, LEM 2015  

The purpose of this study is to develop the new machine bed support mechanism which can reduce the vibration generated in high speed tracking motion. In order to achieve the purpose, frequency response and motion trajectory are measured on the machine supported by the proposed machine bed support which has sliding surface, and compared with the results measured on the machine supported by the conventional one. A mathematical model that can represent the influence of the machine support characteristic is also developed. The simulated frequency responses are compared with the measured ones. As the results from the experiments and simulations, it is confirmed that the vibration generated in high speed tracking motion can be reduced by the proposed machine bed support which has sliding surface.

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society for Precision Engineering  

Recently, the demand to reduce the energy consumption of NC machine tools is increasing. In particular, revealing the energy consumption during cutting process is important, many studies have been accomplished. However, few studies have shown the relationship between the cutting force and energy consumption during cutting process. In this study, in order to clarify the relationship, measurement tests of the power consumption, motor toques and cutting forces arc carried out during peripheral milling operations using square end mills. The tests are carried out with various material removal rate, down and up cuts, and different number of flutes. Losses of each part are evaluated based on the energy consumptions per one cubic millimeter material removal volume. As the results, it is confirmed that the energy consumption during the down cut milling is smaller than it during the up cut milling. It is also confirmed that the higher number of flute reduces the energy consumption.

DOI： 10.2493/jjspe.81.429

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

© 2014 Elsevier Ltd. All rights reserved. Chatter is one of the most limiting factors in improving machining performances. Stability Lobe Diagram (SLD) is the most used tool to select optimal stable cutting parameters in order to avoid chatter occurrence. Its prediction is affected by reliability of input data such as machine tool dynamics or cutting coefficients that are difficult to be evaluated accurately, especially at high speed. This paper presents a novel approach to experimentally evaluate SLD without requiring specific knowledge of the process; this approach is called here Spindle Speed Ramp-up (SSR) test. During this test spindle speed is ramped up, and chatter occurrence is detected by the Order Analysis technique. As result one single test ensures optimal spindle speed identification at one cutting condition, while if few tests are performed the entire SLD could be obtained. Results of the method applied to slotting operation on aluminum are provided and a comparison between different measurements devices is presented. This quick, easy-to-use and efficient test is suitable for industrial application: no knowledge of the process is required, different sensors can be used such as accelerometer, dynamometer or microphone.

DOI： 10.1016/j.ijmachtools.2014.11.013

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KOREAN SOC PRECISION ENG  

© 2015 Korean Society for Precision Engineering. Energy consumption in the manufacturing sector is becoming a very hot topic due to its significant ecological relevance, especially for energy intensive processes such as machining. Machining finds nowadays large application mainly due to its high performance, in terms of both surface finish and tolerances achievable; as an example this is the key technology in dies and molds production, largely used in the automotive and housewares sectors. Process optimization could be carried out using different strategies, as already proposed by many authors, such as by optimizing machining parameters or implementing alternative toolpath capable of reducing both machining time and energy consumption. Within this paper will be presented a novel approach that takes into account the product orientation within the working zone of the machine. Milling machines are usually non symmetric regarding the energy consumptions of the axes due to the different masses that have to be moved, hence product orientation could sensibly affect energy consumption in performing a toolpath. Optimizing product orientation has the advantage not to affect product quality and require no adjustment of machining parameters. An approach to model the machine power consumption and to optimize the workpiece orientation is presented together with the results of validation experiments.

DOI： 10.1007/s40684-015-0001-3

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Fuji Technopress  

© 2015, Fuji Technology Press. All rights reserved. A unique machining knowledge has led to several different perspectives between planners and operators as regards in designing a machining process plan. All precedents have shown the need to maintain a suitable machining process plan. Commercial Computer- Aided Design (CAD) and Computer-Aided Manufacturing (CAM) systems have facilitated the manipulation of 3D models to generate a machining process plan. The open Advanced Programming Interfaces (APIs) are also helpful in tailoring decision support systems to determine process plans. This study proposes an emergent system to generate flexible machining process plans. The proposed system considers the integration between design and manufacturing perspective to produce relevant machining process plan. The generation of process plans begins by considering the total removal volume of the raw material, estimating the removal features, thus analyzing and ordering several candidates of machining process plans. The total machining time and number of setups from each machining process plan candidate is analyzed and evaluated. Eventually, the proposed system is tested using several prismatic 3D models of a workpiece to show the outcomes.

DOI： 10.20965/ijat.2015.p0104

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Language：Japanese   Publisher：International Conference on Advances in Experimental Structural Engineering  

A new type of bridge railing was developed using the extruded multi-hollow-type shape of aluminum-alloy to have the improved cost performance and appearance. First, static tests and numerical simulations were performed using model posts of railing made from aluminium-alloy plate with 70 mm thick to determine the multi-hollow-type sectional dimensions. Then, extruded posts of railing with flange width of 145 mm and 120 mm were tested and analysed to prove the performance following the specifications for the design of the railing in Japan. The static tests and the dynamic tests using heavy weight of 460 kg on extruded aluminum-alloy specimens were conducted to check the ultimate strength, energy absorption capacity and dynamic behaviour. The numerical analysis results of static and dynamic behaviours were almost consistent with the test results. Finally, the collision numerical simulation between the railing and a heavy truck with weight of 25 t, speed of 45 km/h and collision angle of 15 degree was performed. From the test and numerical analysis simulation results, the new type of post was proved to be available for different strength types of bridge railing changing the flange width when cutting the extruded long member.

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Language：Japanese   Publisher：The Japan Society for Precision Engineering  

DOI： 10.2493/jjspe.81.651

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：INT INST ACOUSTICS & VIBRATION  

Especially in the EMS (Electronics Manufacturing Service) companies which manufacture IT product components, reduce the production cost by applying high speed tracking motions capability from machine tools. Therefore higher speed tracking motion always required. However, the motion accuracy gets worse due to mechanical vibration by means of the inertia in high speed motion, the speed is limited. The vibration due to the interaction of feed drive systems with the machine tool structure has a great influence on the relative position between tool and workpiece. In order to improve motion accuracy, the model that can analyse the influence is required. The purpose of this study is to develop a mathematical model which can investigate the relative motions between tool and workpiece. In order to achieve the purpose, in this study, a state space equation model of an NC machine tool which considers vibration of machine tool structure is proposed based on analysed vibration mode of the machine. This model also considers the torsion vibration of the bed and motion characteristics of the feed drive systems. The mass, inertia, stiffness and viscosity are determined based on the calculation and identification by matching the frequency responses. In order to evaluate the effectiveness of the proposed model, vibration modes are simulated and compared with the measured ones. In addition, corner tracking motions and circular motions are measured and simulated. Motion trajectories of feedback position (rotational angle of motors), linear scale positions (axial displacements of the table), and relative position between the spindle nose and the table are measured and simulated in the motions. As the results, it is confirmed that the proposed model can predict the vibration mode and the motion trajectories.

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

A new methodology to automate machining operation planning is proposed. A new machining operation plan is reconfigured from past case data or past machining operation data stored in the database. Machining information, e.g. cutting tool, cutting conditions, tool path pattern, is associated with a machining feature. A machining feature is recognized from the 3D CAD model of the finished shape. Sets of machining information are stored as the past case data with their 3D CAD models. In order to generate a new machining operation plan of a new product, machining features are recognized based on topological relationship of the 3D CAD model first. Then, each of machining feature is compared with machining features contained in 3D CAD models stored as the past case data quantitatively in terms of shape, size and material. Finally, the most similar machining feature is selected as the reference one. The machining information associated with the reference machining feature can be applied for each machining feature recognized in the new product. Finally, the NC program to perform a new machining operation is generated automatically. The usability and effectiveness of this proposed system to save time and effort of human operator was verified through a case study.

DOI： 10.1299/transjsme.15-00280

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：FUJI TECHNOLOGY PRESS  

© 2014 Fuji Technology Press. All rights reserved. This paper proposes a method of simulating the effects of the machining center motion errors onto the finished surface. The proposed simulation method consists of the servo delay models of feed drive systems, a geometrical error model of the machine tool, a machined shape simulator, and a renderer. In order to compare the simulated finished surfaces with the machined one, tests consisting of machining spheres are carried out using a ball-end mill. As result, it is proven that the proposed simulation method can adequately simulate the effects of motion errors on the finished surface. In addition, an investigation into the cause of blemishes is carried out. It is also confirmed that the proposed method can be an effective tool in the identification of the causes of blemishes on the surface.

DOI： 10.20965/ijat.2014.p0801

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：FUJI TECHNOLOGY PRESS  

© 2014 Fuji Technology Press. All rights reserved. In order to achieve flexible and autonomous milling operation, a systemcalled Digital Copy Milling (DCM) was developed in our previous studies. Additionally, tool motion control, in which the voxel information of the removal volume voxel model is referred to, is performed in DCM. In this study, a feed speed control function and tool posture control function are integrated with the DCM by referring to the feed speed and tool posture parameters stored in the voxel properties of the removal volume voxel model. It is assumed that these parameters change gradually as a diffusion phenomenon to automatically determine the voxel properties using a diffusion equation. In order to calculate the diffusion equation, the voxel in the removal volume corresponds to a calculation grid of the diffusion equation and not just to the storage of the feed speed and tool posture parameters. For experimental verification, the feed speed and tool posture parameters were automatically determined, and the tool motion was successfully controlled independent of the tool path generation to perform the milling operation.

DOI： 10.20965/ijat.2014.p0792

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society for Precision Engineering  

Since the energy consumption of production facilities occupies the great portion of the energy consumption in the manufacturing, the energy saving of the production facilities is important. Thus, this study focuses onto the energy consumption of the feed drive system and aims at reduction of its energy consumption. Feed drive systems are widely used for various industrial facilities such as NC machine tools, hence the energy consumption of feed drive systems are directory related with the energy consumption in the manufacturing. In order to achieve the purpose, the energy consumption of the feed drive system is clarified by using the experimental apparatus single axis feed drive system and the energy usages are also estimated by simple mathematical models. The measurement tests are carried out with both of ball-screw and linear motor drives, under several friction characteristics, and several driven mass to investigate the influence of the factors to the energy consumption of the feed drive system. As the results, it is clarified that the energy consumption is influenced by the drive system, friction characteristics of linear guide and velocity loop gain.

DOI： 10.2493/jjspe.80.395

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC MECHANICAL ENGINEERS  

© 2014 The Japan Society of Mechanical Engineers. Although glitches due to motion error of the feed drive systems are typically observed on the machined surface, the relationships between the motion error and glitches are not investigated up to now. The purpose of this study is to clarify the influence of motion error of feed drive systems onto machined surface generated by ball end-mill. In order to achieve the purpose, cutting tests and simulation of hemisphere shape are carried out. The cutting tests of hemisphere are carried out with two kinds of tool paths; uni-directional and bi-directional scanning paths. Parameters of the friction compensator of the NC controller are also changed to investigate the influence of motion characteristics of the machine. In addition, a simulation method for machined surface with the dynamic model of feed drive systems is newly developed. As the results of the cutting tests and simulations, it is confirmed that the proposed simulation method can accurately predict the influences of the motion errors and tool paths onto the machined surface generated by a ball end mill. It is also clarified that the both of motion path and motion errors influence the machined surface, because the innermost motion paths to the work piece are copied onto the finished surface. For example, even if a stepwise error exists on the motion trajectories, the error is not copied onto the finished surface when the surface is generated by bi-directional tool paths, although the error clearly copied on to the surface generated by uni-directional tool path.

DOI： 10.1299/jamdsm.2014jamdsm0044

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ELSEVIER SCIENCE BV  

In the machining process the dynamic behaviors of machine tools, such as tool vibration, vibration of mechanical structure, and motion error of feed drive systems, influence the machined surface. However, the influence of dynamic ehaviors onto the machined surface generated by simultaneous five-axis motion has not been investigated up to now. This study focuses on the influence of motion error of translational and rotary axes onto the machined surface generated by a simultaneous five-axis motion. The geometry used for the tests is the cone frustum, which is typically used for evaluating machining accuracy of five-axis controlled machine tool. A method to simulate the tool motion trajectory and tool orientation for a five-axis machine has been developed based on the modeling of he feed drive systems considering their dynamic characteristic. The machined surface of cone frustum is predicted based on the simulated results. In order to verify the validity of simulation result and the influence of motion error in each axis on the finished surface, cutting tests have been carried out. The tests have proven that the proposed simulation method can predict the machined surface. The influence of motion error in each axis on finished surface is also discussed based on the results of cutting tests and simulations. Selection and peer-review under responsibility Performance Cutting. f the International Scientific Committee of the 6th CIRP International Conference on High © 2014 Elsevier B.V. © 2014 Published by Elsevier B.V.

DOI： 10.1016/j.procir.2014.03.067

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ELSEVIER SCIENCE BV  

An actual machining center specification, e.g. the axes travel, the workpiece size allowance, etc.; needs to be considered for constructing a machining process plan. In this paper, a machinable space of a five-axis machining center is proposed for simulating the workpiece setup. The machinable space is constructed by a table region and a tool cone. The tool cone is an allowance of the spindle diameter and the cutting tool length. By fitting in the visibility area from a total removal volume (TRV) of the machining process plan, a TRV network can be established. The workpiece setup is estimated by positioning the TRV network within the table region. The positioning process can be used for estimating the number of setup changes on the corresponding machinable space. © 2014 Published by Elsevier B.V.

DOI： 10.1016/j.procir.2014.03.008

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society for Precision Engineering  

NC machine tools generate desired shapes by control relative motions between tool and workpiece. Since several motion paths exist to machine the products with NC machine tools, it is difficult to choose the suitable motion path for the machining. This study focuses onto the energy consumption of feed drive systems of NC machine tools during the machining motion. In this study, an evaluation method by prediction of the energy consumption for each tool path is proposed. The evaluation method can predict the energy consumption of the feed drive systems during the motions. In order to confirm the correctness of the proposed method, actual measurement tests of the energy consumption are carried out. As the results, it is confirmed that the proposed method can evaluate the motion path based on the energy consumption.

DOI： 10.2493/jjspe.80.699

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japanese Society of Manufacturing Engineers  

DOI： 10.1299/kikaic.79.4543

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japanese Society of Manufacturing Engineers  

DOI： 10.1299/kikaic.79.4613

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japanese Society of Manufacturing Engineers  

DOI： 10.1299/kikaic.79.4572

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：The Japanese Society of Manufacturing Engineers  

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：The Japanese Society of Manufacturing Engineers  

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：The Japanese Society of Manufacturing Engineers  

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society for Precision Engineering  

Reducing the electric power consumption in NC machine tools is strongly demanded in these years, because the NC machine tools are one of the main facilities in the manufacturing field. Thus measuring tests of the power consumption in an NC machine tool for all components were measured in other studies up to now. This study focused onto the power consumption of feed drive systems. In this study, electric power consumption of an actual 5-axis vertical type machining center consists of X, Y, Z, B and C axes is measured. In order to investigate the electric power consumption of feed drive systems, currency and voltage of servo amplifiers are measured. At first, the measuring tests of each axis are carried out under various feed rate. As the results of the measurements, it is clarified that the power consumption depends on the motion velocity and torque. In addition, acceleration-deceleration parameters and servo gains are also changed to investigate the influences of the parameters. These parameters have big influences on the power consumption during the acceleration-deceleration process. The results of this study show that the electric power consumption might be reduced by changing the motion and parameters of the axes.

DOI： 10.2493/jjspe.79.930

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Other Link： http://www.lib.kobe-u.ac.jp/handle_kernel/90001949

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：JSME  

DOI： 10.1299/kikaic.79.3854

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SME  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Fuji technopress  

An autonomous and intelligent machine tool that performs machining operations by referring to CAD product data was developed in our previous study to solve fundamental issues with the conventional command method, which uses NC programs. A system, Digital CopyMilling (DCM), digitizing the principle of copymilling, was developed to generate tool paths during milling operations for dynamic tool motion control. In the DCM, the cutting tool is controlled dynamically to follow the surface of a CAD model corresponding to product shape, eliminating the need for the preparation of NC programs. Active tool motion controls were also realized to enhance the function of DCM. In this study, surface roughness control of the finished surface is realized as an additional enhanced function of DCM to achieve autonomous milling operations. This function allows the DCM to select cutting conditions and generates tool paths dynamically to produce the desired surface roughness: from rough, through semi-finished, to finished. The verification experiment is successfully carried out.

DOI： 10.20965/ijat.2013.p0401

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Language：Japanese   Publisher：精密工学会  

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Language：English   Publishing type：Research paper (scientific journal)  

The present paper describes the effect of the half apex angle of the cone-frustum on the motion trajectory under simultaneous five-axis motion and the effect of the sensitive direction of the ball bar when the motion trajectory is measured along the three-dimensional circular conical path. In the present paper, simulation of the measurement by means of a ball bar instrument is mainly conducted using a motion simulator developed previously. In particular, a precise mathematical model was developed to express the pitch errors of the axes of rotation of the five-axis machining center having a tilting rotary table driven by worm gears. In the experiment and simulation, primarily the center position and half apex angle of the cone-frustum were varied. In addition, two sensitive directions of the ball bar were investigated. The motion simulator incorporating the pitch error model can express the detailed trajectories obtained by the ball bar, even if the half apex angle and center position of the cone-frustum and the sensitive direction of the ball bar were changed. Then, the influence of the frictional force of the linear axes of motion, and the backlash and pitch error of the axes of rotation on the circular trajectories were analyzed. In particular, for the case of a half apex angle of 45°, the trajectory due to the errors of the axis of rotation is strongly affected by the sensitive direction of the ball bar. © 2012 Elsevier Ltd.

DOI： 10.1016/j.ijmachtools.2012.07.013

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

Decision of the workpiece setting is an important issue in process planning for both 5-axis and multi-tasking machine tools. However, it is difficult to decide the workpiece setting properly and a huge amount of time and effort is required for trial-and-error verifications of NC programs using a virtual machining simulation. Still, in the worst case, the workpiece re-setting is needed to complete machining operation. In order to reduce the trial-and-error verifications, it is important to decide the workpiece setting properly first. In this study, a machinable space derivation method to find the suitable workpiece setting position is proposed. For this purpose, the reachable space of cutting tool tip is calculated based on the relative motion between the cutting tool and the machine table. In the case of 5-axis control machining, the reachable space of cutting tool tip, which changes according to the tool posture, can be visualized. Then, the machinable space can be represented by overlaying the reachable spaces obtained for different tool postures. The machinable space derived is help full to decide the workpiece setting properly at the early stage in the process planning. In the case studies for both 5-axis and multi-tasking machine tools, it is verified that the workpiece setting is decided effectively to complete machining operation by referring the machinable space.

DOI： 10.1299/kikaic.79.4543

CiNii Research

Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

Decision of the workpiece setting is an important issue in process planning for both 5-axis and multi-tasking machine tools. However, it is difficult to decide the workpiece setting properly and a huge amount of time and effort is required for trial-and-error verifications of NC programs using a virtual machining simulation. Still, in the worst case, the workpiece re-setting is needed to complete machining operation. In order to reduce the trial-and-error verifications, it is important to decide the workpiece setting properly first. In this study, a machinable space derivation method to find the suitable workpiece setting position is proposed. For this purpose, the reachable space of cutting tool tip is calculated based on the relative motion between the cutting tool and the machine table. In the case of 5-axis control machining, the reachable space of cutting tool tip, which changes according to the tool posture, can be visualized. Then, the machinable space can be represented by overlaying the reachable spaces obtained for different tool postures. The machinable space derived is help full to decide the workpiece setting properly at the early stage in the process planning. In the case studies for both 5-axis and multi-tasking machine tools, it is verified that the workpiece setting is decided effectively to complete machining operation by referring the machinable space. © 2013 The Japan Society of Mechanical Engineers.

DOI： 10.1299/kikaic.79.4543

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCI LTD  

The present paper describes the enhancement of kinematic accuracy of five-axis machining centers with a tilting rotary table. Geometric deviations inherent to the five-axis machine are calibrated through the actual trajectories measured by two different settings of a ball bar in simultaneous three axis motion. Measurement using a cylindrical coordinate system is superior to measurement using a Cartesian coordinate system from the viewpoint of the number of measurements. In order to verify the effectiveness of the calibration method, the inherent geometric deviations measured on the cylindrical coordinate system were corrected through the post processing of NC data for cutting the cone-frustum. The relative displacement between the tool center point and the workpiece was detected by the ball bar. Based on the experimental results, it is confirmed that the radius, center position, and roundness of the three-dimensional circular trajectory are improved when the inherent geometric deviations are corrected. © 2013 Elsevier Ltd.

DOI： 10.1016/j.ijmachtools.2012.12.008

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In this study, in order to investigate the power consumption of feed drive system, a mathematical model to predict for the electric power consumption of feed drive systems is proposed by using the single-axis experimental apparatus. This can be driven by either of ball screw or linear motor and it is possible to change the mechanical properties of the machine such as grease viscosity of the table. The power consumption is simulated by proposed simulation method based on the mathematical model of feed drive system and the simulated results are compared with the measured results of the experimental apparatus to confirm the validity of the simulated results. In addition, it is clarified that the energy usages of the feed drive system. The energy losses of the feed drive system are divided into the loss of viscous friction, coulomb's friction, servo amplifier, and motor. These energy losses are calculated by the proposed model. Then, it is investigated that the influence of the velocity and the friction to the power consumption of feed drive system experimentally. As the results, it is confirmed that proposed simulation method can accurately predict the power consumption of the ball-screw feed drive system. It is also clarified that the friction energy loss of ball-screw drive is larger than one of linear motor drive, and the friction characteristics of linear guides influences the power consumption of linear motor drive system. Copyright © 2013 by ASME.

DOI： 10.1115/IMECE2013-63518

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC MECHANICAL ENGINEERS  

The present paper describes the sensitivity coefficient of measurement in the three-dimensional circular interpolation movement that is equivalent to cone-frustum cutting in five-axis machining centers with a tilting rotary table. The sensitive direction of a ball bar having a one-dimensional displacement sensor is parallel to its telescopic bar. In the present paper, the ratio of the measurement value to the actual error is defined as the sensitivity coefficient of measurement. The sensitivity coefficient of each axis is calculated by changing the apex angle and location of the cone-frustum. Different trajectories are obtained according to the attitude of the ball bar. This is due to the resulting variation in the sensitivity coefficient of the ball bar. If the ball bar is set parallel to the base circle of the cone-frustum, and if the center of the cone-frustum is positioned away from the centerline of the rotary table (in the positive direction of the linear axis that is perpendicular to the tilting axis of the table), the trajectory can be obtained appropriately. Copyright © 2013 by JSME.

DOI： 10.1299/jamdsm.7.317

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Language：Japanese   Publisher：Society of Automotive Engineers of Japan  

Synchromesh mechanisms are commonly applied to transmissions because it can effectively help shift change process. Dynamic behavior of transmissions with synchromesh mechanism has not been investigated although the dynamic behavior of the synchromesh mechanism influences the vehicle behaviors. In this study, a mathematical model for a transmission with the synchromesh mechanism is proposed to analyze the dynamic behaviors during the shift changing motions. The model consists of inertias, torsion stiffness, frictions, and a model for the synchromesh mechanism. In order to confirm the validity of the proposed model, the model is applied to an experimental setup which is controlled by a PC. As the results of experiments and simulations, it is confirmed that the proposed model can qualitatively evaluate the dynamic behavior during the shift change motions.

DOI： 10.11351/jsaeronbun.44.405

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

Dynamic motion errors exist due to servo characteristics in parallel kinematic mechanism (PKM) machine tools with 6 degrees of freedom. In this study, at first, analytical investigation is carried out using transfer function of local servo system and Jacobian matrix, in order to clarify the causes of the particular dynamic motion characteristic on errors in PKM machine tools. As the results of the analysis, it is newly founded that the discrepancy between two coordinate transformations, which are used for inverse kinematics calculation and for forward kinematics calculation, causes the particular motion errors. After that, a feedback controller based on the tool tip position and orientation is proposed in order to compensate the particular motion errors. As the results of circular motion simulations, it is clarified that proposed feedback control system, which refers the predicted tool tip position and orientation and consists of Jacobian matrix, can eliminate the particular motion errors of PKM machine tools successfully.

DOI： 10.1299/kikaic.79.3854

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (conference, symposium, etc.)   Publisher：Japan Machine Tool Builders' Association  

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This paper proposes a mathematical model of a CNC rotary table driven by a worm gear. The CNC rotary tables are generally utilized as rotary axes of 5-axis machining centres. In this study, a mathematical model which can simulate dynamic behaviours of rotary table is proposed. The model consists of inertia of motor, spur and worm gears, and table. Axial displacement of the worm is also considered into the model. Various motions are measured and simulated to confirm effectiveness of the model. As the results show, the proposed model can simulate step response, rotational fluctuations, and influence of unbalanced mass. Copyright © 2012, IGI Global.

DOI： 10.4018/ijimr.2012100103

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Circular motion tests are commonly used to evaluate the accuracy of the motion of feed drive systems. However, large quadrant glitches are often observed in circular trajectories as the motion changes across the x and y quadrants. It is well known that this phenomenon is caused by friction forces acting on the feed drive mechanism. This paper investigates the generation process of quadrant glitches and proposes a quadrant glitch compensator based on the investigation. As a result of the experiments and simulations, it is clarified that the axis velocity does not stay at zero during direction changes and that the proposed generation mechanism model for quadrant glitches accurately describes actual behavior. It is also confirmed that the proposed friction compensator can eliminate quadrant glitches effectively even if the radius and feed rate change.

DOI： 10.20965/ijat.2012.p0154

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

This paper describes the testing method for five-axis machining centers using three-dimensional circular interpolation movement equivalent to the cone-frustum cutting. It is assumed in the simulation that a ball bar system is used as a measuring device that can freely moves in 3D space. The ratio of a measurement value by the ball bar and a real error of each axis is defined as a sensitivity coefficient of axis. The sensitivity coefficient of each axis was calculated changing the apex angle and the center location of virtual cone-frustum. The 3D circular movements are simulated, and the effect of the pitch errors of the axes of rotation was investigated by changing the sensitive direction of the ball bar. From the view point of sensitivity coefficient, it is pointed out that if the measurement is conducted by the ball bar which is parallel to the bottom of a cone-frustum whose center is set away from the center line of the axis of rotation, it is possible to measure the movement errors of five axes. © 2012 The Japan Society of Mechanical Engineers.

DOI： 10.1299/kikaic.78.2677

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ELSEVIER SCIENCE BV  

The present paper describes a testing method for five-axis machining centers using three-dimensional circular interpolation movement equivalent to cone-frustum cutting. In the present paper, the test conditions, such as the half apex angle of cone-frustum and the sensitive directions of the ball bar device were investigated. In addition, the sensitivity coefficient of each axis was investigated. It is found from the analysis of the sensitivity coefficient that the trajectory due to the errors of the axis of rotation is strongly affected by the sensitive direction of the ball bar for the case of a half apex angle of 45°. © 2012 The Authors.

DOI： 10.1016/j.procir.2012.04.094

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In virtual machining simulation to verify NC programs for machining operation, construction of 3D (three-dimensional) models of cutting tools to be used and identification of posture and position of workpiece to be machined are quite important to achieve reliable verification. Especially, a 3D model construction of cutting tools requires skill-full operations and it takes much time and cost. Several geometric parameters to define cutting tool shapes are needed to construct precise 3D models for virtual machining simulation. Even though, careless mistake to set parameters of tool diameter and length causes machining troubles. Therefore, no trouble was happened in virtual machining simulation, it is still required to check machining troubles through the trial-cutting on actual NC machine tools. In this paper, new methods to construct 3D models of cutting tools and identification of posture and position of workpiece are proposed. Experimental measurement of cutting tool shape is performed on the machine tool using a CCD camera, and a 3D model of cutting tool was constructed successfully. By this method, setting of invalid parameters to define cutting tool shapes can be avoided. Also, posture and position of the workpiece can be identified successfully. These parameters can be used to detect wrong setup operation before actual machining operation. Copyright © 2012 by ASME.

DOI： 10.1115/ISFA2012-7204

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ELSEVIER SCIENCE BV  

This study proposes motion control techniques which can improve dynamic synchronous accuracy between translational and rotary axes in five-axis machining centres. The proposed techniques consist of servo gain tuning, feed forward controller design, signal delay and backlash compensator, rotational fluctuation compensator and jerk limited acceleration process design. In order to evaluate the effect of proposed techniques, experimental tests are carried out. An experimental apparatus consists of X, Y, and C axes is provided for the experiments. Any control algorithm can be implemented into the experimental apparatus because the system is controlled by a personal computer with a DSP board. Translational X and Y axes are powered by AC servo motors and ball screws. A rotary C axis is powered by an AC servo motor, spur and worm gears. Three kinds of synchronous motions are applied to evaluate the dynamic synchronous accuracies. They are; non-uniformed simultaneous 3-axis motion, simultaneous 2-axis motion of X and C axes, and ellipse shape machining motion using simultaneous 3-axis motion. It is clarified from the experiments various factors including signal delay of rotary encoders influence the dynamic synchronous accuracy between translational and rotary axes, and the proposed motion control techniques can significantly improve the dynamic synchronous accuracy without velocity limitations. © 2012 The Authors.

DOI： 10.1016/j.procir.2012.04.048

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ELSEVIER SCIENCE BV  

In order to develop an autonomous and intelligent machine tool, a system named Digital Copy Milling (DCM) was developed in our previous studies. The DCM generates tool paths in real time based on the principle of copy milling. In the DCM, the cutting tool is controlled dynamically to follow the surface of CAD model corresponding to the machined shape without any NC program. In this study, surface roughness control of finished surface is performed as an enhanced function of DCM. From rough-cut to semi-finish-cut and finish-cut operations, the DCM selects cutting conditions and generates tool paths dynamically to satisfy instructed surface roughness Ra. The experimental verification was performed successfully. © 2012 The Authors.

DOI： 10.1016/j.procir.2012.10.007

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

In the present paper, a mathematical model was developed to represent the pitch error of the axes of rotation of five-axis machining centers having a tilting rotary table. The parameters used in the model were determined based on data measured for simultaneous three-axis motion. In experiments and simulations, the center offset and half apex angle of the cone-frustum are varied. In addition, the sensitive direction of the ball bar is varied to be either perpendicular to the conical surface or parallel to the bottom surface of the cone frustum. The simulation results obtained for different half apex angles, center positions of the cone-frustum, and sensitive directions of the ball bar are in good agreement with the experimental data. Then, the effects of the friction torque of the linear axes and the backlash and pitch error of the axes of rotation are simulated in order to analyze the experimentally obtained circular trajectories. When the center position of the cone-frustum is located far from the center line of the axis of rotation in the Y direction, the circular traj ectory is affected by the sensitive direction of the ball bar and the half apex angle of the cone-frustum. In particular, for the case of a half apex angle of 45 degrees, the trajectory is strongly affected by the errors of the axis of rotation. © 2012 The Japan Society of Mechanical Engineers.

DOI： 10.1299/kikaic.78.964

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Language：English   Publishing type：Research paper (scientific journal)  

Feed drive systems consisting of servo motors and ball screws are generally used with NC machine tools, wire bonders, tip mounters, etc. Higher speed and accuracy are continuously required to the feed drive systems. In order to achieve higher performance of the systems, it is effective to analyze the dynamic behaviors using simulations. This study proposes a feed drive simulator consists of parameter identification and simulation modules. The parameter identification module consists of 3 sub-modules; identification system for friction forces, identification system for frequency response, and identification system for electric delay. The identification algorithms for unknown parameters are newly proposed. The simulation module is based on a mathematical model which consists of mass, inertias, stiffness, damping, frictions, servo gains, electrical delay, and control frequency. The simulation module also has a servo tuning function. The simulator, which includes a Graphical User Interface (GUI) was developed using Visual C++. Actual feed drive systems were used to confirm the effectiveness of the simulator. It was confirmed that the simulator identifies parameters systematically, simulates physical values for different motions, and automatically determines servo gains based on the parameters identified.

DOI： 10.20965/ijat.2011.p0875

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This paper describes the dynamic synchronous accuracy of the translational and rotational axes in five-axis machining centres. In this study, non-uniform three-axis synchronous motion is investigated in order to estimate the dynamic synchronous accuracy. A dynamic model of each axis including a rotary axis is developed, and the synchronous motion is simulated. The dynamic model consists of a moment of inertia, Coulomb's friction, viscous friction, and controllers. As a result of the experiment and simulation, it is clarified that the developed model can express the experimental results accurately. In addition, a controller tuning method that can improve the synchronous accuracy is proposed, and its effectiveness is clarified by the developed dynamic model. Copyright © 2011 Inderscience Enterprises Ltd.

DOI： 10.1504/IJMMS.2011.041469

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Language：English   Publishing type：Research paper (scientific journal)  

NC controllers use different types of compensation systems to improve motion accuracy of feed drive systems against pitch error, friction, backlash, and elastic deformation. Compensators for static error, such as pitch and squareness errors, are tuned semiautomatically. However, for dynamic error such as quadrant glitches and vibration, parameter tuning takes too much time. In this study, motion trajectory measurement for parameter tuning using accelerometers has been proposed. In the methods, displacements of each axis can be obtained from measured accelerations along each axis. Although the obtained displacements include some errors, such as setting error, sensitivity error, and integral error in numerical integration, the errors can be compensated for based on the feedback positions measured simultaneously. To confirm the feasibility of the proposed methods, measurement tests using a grid encoder are carried out. Results of the measurements confirm that the circular trajectories and vibrations can be measured by the proposed method. Automatic parameter tuning method for the backlash compensator is also proposed.

DOI： 10.20965/ijat.2011.p0387

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In order to achieve flexible machining operations, a system called Digital Copy Milling (DCM) was developed in our previous studies. The DCM is the original concept to achieve the direct milling operation, which does not require any NC program to perform machining operations. In this study, Voxel representation of removal volume is introduce to enhance the function of the DCM. By utilizing Voxel property corresponding to tool posture, active tool posture control, which is independent of tool path generation in 5-axis milling can be realized. The experimental verification was performed successfully.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：JAPAN SOC MECHANICAL ENGINEERS  

The purpose of this study is to clarify the relationship between the dynamic motion error of feed drive systems and the machined surface. In order to achieve the purpose, simulation method for the machined surface of the swarf cutting is newly proposed. In addition, in order to clarify the correctness of proposed method, actual cutting tests are carried out. As the results of the cutting tests, it was confirmed that the influence of the motion error of feed drive systems on machined surface can be predicted by the proposed simulation method.

DOI： 10.1299/jamdsm.6.781

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This paper proposes an estimation method for wear of ball screw and support bearing is proposed. In order to develop the estimation methods, special ball screws and support bearings with larger clearance are installed into a feed drive system, and the worn characteristics are investigated. In the estimation method which proposed based on the investigations, sine wave motions under various frequency are commanded into the feed drive system, and quantity of wears can be estimated based on amplitude of feed backed positions and current. It is experimentally clarified that the proposed estimation method can estimate the amount of the wear accurately.

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Language：Japanese   Publishing type：Research paper (international conference proceedings)   Publisher：The Japan Society of Mechanical Engineers  

In a machining center with an offset preloaded ball screw, the quadrant glitch has two peaks, because the friction torque fluctuates due to the changing contact points between the balls and the grooves of the ball screws. In this study, a method for compensating the two peaks of quadrant glitches is proposed. This proposed compensation method uses a new mathematical friction model to cancel the friction torque changes generated in the ball screws. It is confirmed that the proposed method can correct the two peaks of quadrant glitches in a wide feed speed range with high accuracy. In addition, in circular motions with mass, such as the workpiece, it is confirmed that the proposed method can correct the quadrant glitches without deteriorating the mass effect.

DOI： 10.1299/kikaic.78.1211

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Language：Japanese   Publisher：精密工学会  

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

This paper proposes a mathematical model of a feed drive system consisting of a cylindrical linear motor and linear ball guides. The friction model consists of two components; a model for the relationships between displacement and friction force under microscopic motion (non-linear spring characteristic), and a model for the relationship between velocity and friction force (Stribeck curve). The non-linear spring is modeled from the results of very low frequency simple harmonic motion experiments. The Stribeck curve is modeled from the results of friction force experiments conducted for various constant velocities. The parameters in the model were derived from machine specifications of the feed drive system and experimental results. To evaluate the proposed model, step responses and circular motion under various conditions were measured and simulated. The influence of the friction characteristics on dynamic behavior was then investigated. In the experiment, the friction characteristics were changed and compared using three greases with differing viscosities. As a result, it was confirmed that differences in grease viscosity strongly influence the damping of vibrations for the step responses.

DOI： 10.1299/kikaic.75.470

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Publishing type：Research paper (international conference proceedings)  

In this study, a method of compensating for quadrant glitches was developed, and its effectiveness was verified through simulation and experiments. The compensation method combines the newly developed 'torque following compensator' with the friction compensator, which was previously developed by our group. Using only the newly developed compensator, it was found that this compensator can decrease the height of quadrant glitches by about 50% and can effectively correct fluctuations in the height due to friction force changes. Using the friction compensator together with the torque following compensator, it was confirmed that the quadrant glitches were effectively removed.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER SOC MECHANICAL ENGINEERS  

In this paper, the characteristics of two rotary tables driven by worm gear and roller gear cam are measured and compared. The positioning accuracy and repeatability as specified in ISO 230-2 are measured together with the rotational fluctuation, backlash, friction torque, frequency response of the systems and also the influence of unbalance mass on rotational motion. Two rotary encoders which were attached to motor and output axis were used for measurements. The motor, controller, and the rotary encoders were kept the same for both tables to ignore the effects of these units on results. Furthermore, the simulations were carried out by mathematical models which were proposed by two of the authors and the results were compared with measured results. From the simulation results, the torsional stiffness and friction torque were identified and also compared. The results show that the measured and simulated data have a good agreement and therefore it can be said that the identified parameters from simulations are accurate. The result shows that the performances of the rotary table driven by roller gear cam is better than that of rotary table driven by worm gear. Copyright © 2008 by ASME.

DOI： 10.1115/IMECE2008-66108

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

This paper describes the motion control techniques of rotary tables for 5-axis machining centers. Especially, in the machining of complex shapes such as impellers, three translational axes and two rotary ones are simultaneously controlled. A tilting rotary table powered by the worm gear is generally applied as the rotary axes for the 5-axis machining centers, and various causes of inaccuracy exist in the rotary axes. In this study, the causes of inaccuracy are investigated by the experiments and simulations. As the result, it is clarified that the main causes of inaccuracy : servo response, fluctuation of rotational velocity, backlash and the signal delay of rotary encoder. Motor torque saturation of the rotary axis also yields a problem. Based upon the investigated results, some compensators for the problems were proposed. In order to confirm the effectiveness of the proposed compensators, the compensators were applied to an experimental set-up including a rotary axis. As the results, it is clarified that the proposed compensators can much improve the synchronous accuracy.

DOI： 10.1299/kikaic.74.60

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC MECHANICAL ENGINEERS  

This paper proposes a mathematical model of a feed drive system consisting of a cylindrical linear motor and linear ball guides. The friction model consists of two components; a model for the relationships between displacement and friction force under microscopic motion (non-linear spring characteristic), and a model for the relationship between velocity and friction force (Stribeck curve). The non-linear spring is modeled from the results of very low frequency simple harmonic motion experiments. The Stribeck curve is modeled from the results of friction force experiments conducted for various constant velocities. The parameters in the model were derived from machine specifications of the feed drive system and experimental results. In addition, in order to account for the quantization error of the linear scale, the controller and amplifier were modeled as a discrete time system. To evaluate the proposed model, step responses and circular motion under various conditions were measured and simulated. The influence of the friction characteristics on dynamic behavior was then investigated. In the experiment, the friction characteristics were changed and compared using three greases with differing viscosities. As a result, it was confirmed that differences in grease viscosity strongly influence the damping of vibrations for the step responses. Furthermore, it was clarified that quadrant glitches do not appear in the microscopic displacement region. For many simulation results, it was verified that the proposed model accurately reflects the real behavior.

DOI： 10.1299/jamdsm.2.675

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Publisher：The Japan Society for Precision Engineering  

This paper proposes a friction compensator based on the friction characteristics in the microscopic displacement region. In order to evaluate the motion accuracy of feed drive systems for the NC machine tools, circular tests are generally applied. It is known that the large quadrant glitches are often observed on the circular trajectories, and it is caused by the friction forces of the mechanism. In this paper, the relationship between table displacement and total friction torque around the motor axis is modeled by a simple friction model which can accurately estimate the behavior of the friction torque. The proposed friction model is a function of the table displacement, not a function of velocity. Based on the friction model, a friction compensator is invented. The proposed friction compensator consists of a table position estimator, an inverse transfer function of the servo motor, and the friction model. From the experimental and simulation results, it is clarified that the quadrant glitches can be effectively eliminated by the proposed friction compensator, even if the radius and feed rate of circular motion change.

DOI： 10.2493/jjspe.74.622

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

This paper investigates friction characteristics of the linear ball guides. Linear ball guides are generally used for guiding linear motions of feed drive systems. In this study, friction characteristics of the linear ball guides are measured by using a core-less linear motor. As a result of the mathematical analysis, it have been confirmed that the friction force of the guides can be measured as a thrust force command in the experimental system. Measurement tests were carried out for three sizes of guides, three types of greases, three types of pre-load, and with or without of retainer. Firstly, relationships between velocity and friction force are discussed. As the results, it is clarified that the relationship between velocity and friction force depends on the grease viscosity, and the diameter of rolling ball. Non-linear spring characteristics in microscopic region are also measured. As the results of the measurement, it can be said that the non-linear spring characteristics depend on the size of the ball, pre-load, and retainer. The differences of the non-linear spring characteristics have influence on the vibration dumping of step responses.

DOI： 10.1299/kikaic.73.2811

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

This paper proposes a controller design method of feed drive systems to improve the multi-axis synchronous accuracy. In the design method, the velocity loop control systems are designed based upon "the Partial Model Matching Method", and the positional loop control systems are designed by using the frequency characteristics of the designed velocity control loops. A feed forward controller which can compensate servo delay is also proposed. Parameters of the proposed controllers can be determined systematically without trial and error. The effectiveness of the proposed method was evaluated through the experiments and simulations. The experiments were carried out by using the X-Y stage system. The effectiveness of the proposed method in the multi-axis synchronous motion including rotary axes was also evaluated by the simulations of multi-axis machining. As the results of the experiments and simulations, it is clarified that the proposed method can greatly improve the synchronous accuracy.

DOI： 10.1299/kikaic.73.693

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Language：English   Publishing type：Research paper (international conference proceedings)  

The purpose of research work is to develop a clinometer to measure the angular positioning deviations of a tilting axis with high accuracy. Five-axis machining centers consist of three translational axes and two rotary axes. The positioning accuracy of their three linear axes is checked by a laser interferometer. However, there is no measuring instrument to be able to measure the positioning accuracy of the tilting table whose center line is lower than the top surface of the table, automatically. Thus, a clinometer is developed for measuring the tilting axis of the five-axis machines table. The developed servo-clinometer consists of a rotary encoder and a pendulum with a precision level. When the clinometer mounted on the tilting rotary table moves around the tilting axis, the pendulum moves according to gravity and then its direction of the pendulum is adjusted by the servo-mechanism. Through the experiment, it was confirmed that the developed clinometer is enough to apply to the measurement of the tilting deviations.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPRINGER-VERLAG LONDON LTD  

Quadrant glitches are often observed on the circular trajectories of NC machine tools. In this study, a friction compensator that can compensate for the friction characteristics in a microscopic region is proposed. In the compensator, friction forces and torques are modeled using a simple mathematical model, and the estimated friction torque around the motor axis is added to the torque command. In order to evaluate the effectiveness of the proposed friction compensator, the compensator was applied to an actual feed drive system and its mathematical model. As the results of the experiments and simulations, it was confirmed that the proposed friction compensator can eliminate the quadrant glitches effectively, even if the radius and feed rate change.

DOI： 10.1007/978-1-84628-988-0_70

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC MECHANICAL ENGINEERS  

This paper proposes a new method for evaluating the synchronous inaccuracy of a translational axis and a rotational axis in five-axis controlled machining centers with a tilting rotary table. A circular trajectory whose shape is easy to evaluate the specific features is adopted for measuring the circular path described by the two axes. The influence of inaccurate synchronization on the circular path was simulated by changing the distance between the centers of the rotary table and the circular path, the radius of the circular path and the feed speed. Measurement conditions were determined based on the simulation results, and then ball bar measurements and machining experiments were conducted. From the simulation and experimental results, it is confirmed that the proposed method can be used for evaluating the inaccurate synchronization of a translational axis and a rotational axis. However, careful alignment of the center of the rotational axis and the machine coordinate origin is important for evaluating the synchronous accuracy. The ratio of the distance between both centers of the rotational axis and the circular path to the radius provides useful information for the evaluation.

DOI： 10.1299/jamdsm.1.24

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This paper describes the motion control techniques of rotary tables for the 5-axis machining centers. In the 5-axis machining centers, various causes of inaccuracy exist in the rotary tables. In this study, the causes of inaccuracy are investigated. As the result, it is clarified that the main causes of inaccuracy: servo response, fluctuation of rotational velocity, backlash and the signal delay of rotary encoder. Motor torque saturation of the rotary axis also yields a problem. Based upon the investigated results, some compensators for the problems were proposed. It is clarified that the proposed compensators can much improve the synchronous accuracies.

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This paper proposes a mathematical model of a feed drive system consisting of a rod type linear motor and linear ball guides. The mathematical model of the feed drive system consists of vibration model and friction model. The vibration model has three degrees of freedom; vibrations of a rod, a table, and a base. The friction model is consisting of two components; a model for the relationships between displacement and friction force under micro-scopic motion (non-linear spring characteristic), and a model of the relationship between velocity and friction force. In older to evaluate the proposed model, step responses and circular motion under various conditions were measured and simulated. As the results, it was confirmed that the proposed model can express the actual behaviors accurately.

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：The Japan Society of Mechanical Engineers  

This paper describes a newly proposed method for evaluating the synchronous inaccuracy of the translational and rotational axes in five-axis controlled machining centers. The circular motion of which shape is easy to evaluate is adopted for measuring the trajectory described by the axes in the proposed method. The influence of inaccurate synchronization on the circular trajectory was simulated changing the distance between the centers of the rotary table and the circular motion, the radius of the circular motion, and the feed speed. The measurement conditions were determined based on the result of the simulation, and the cutting experiments and the measurements with the ball bar were conducted. From the simulation and experimental results, it is confirmed that the proposed method is able to use for evaluating the inaccurate synchronization of the translational and rotational axes. The ratio of the distance between both centers of the rotational axis and the circular path to the radius provides useful information for the evaluation.

DOI： 10.1299/kikaic.72.3672

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Language：Japanese   Publisher：The Japan Society for Precision Engineering  

This paper describes the dynamic synchronous accuracy between the axes of translational and rotational in a 5-axis machining center. The 5-axis machining centers are applied to machining complex shapes, such as turbine blades and impellers. When the 5-axis machining centers are used to machine complex shapes, the velocity of each axis varies greatly. Therefore, the synchronous accuracy of each axis is an important factor to generate high accuracy shapes. In this study, non-uniform 3-axis synchronous motion was investigated in order to estimate the dynamic synchronous accuracy. A dynamic model of the each axis including a rotary axis was developed, and the synchronous motion was simulated. As the results of experiment and simulation, it is verified the developed model can express the experimental results accurately. In addition, a method that can improve the synchronous accuracy is proposed, and its effectiveness is clarified by the developed dynamic model.

DOI： 10.2493/jspe.72.73

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This paper provides more details of dynamic behaviors of the feed drive system which consists of an AC servo motor and rolling elements etc. In the feed drive system, the nonlinear behaviors of the internal structure of the rolling element have an crucial influences on precise control performance. Our special interest is how to verify the fundamental data of dynamic behaviors of the feed drive system in the vicinity of a microscopic displacement. Experimental data show that the driving torque curve becomes distorted as the input amplitude of sinusoidal wave to the system gets larger, but the curve forms are independent of the input frequencies.

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This paper describes the dynamic synchronous accuracy between the axes of translational and rotational in a 5-axis machining center. The 5-axis machining centers are applied to machining complex shapes, such as turbine blades and impellers. When the 5-axis machining centers are used to machine complex shapes, the velocity of each axis varies greatly. Therefore, the synchronous accuracy of each axis is an important factor to generate high accuracy shapes. In this study, non-uniform 3-axis synchronous motion was investigated in order to estimate the dynamic synchronous accuracy. A dynamic model of the each axis including a rotary axis was developed, and the synchronous motion was simulated. As the results of experiment and simulation, it is verified the developed model can express the experimental results accurately. In addition, a method that can improve the synchronous accuracy is proposed, and its effectiveness is clarified by the developed dynamic model. © 2006, The Japan Society for Precision Engineering. All rights reserved.

DOI： 10.2493/jjspe.72.52

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Language：Japanese   Publisher：The Japan Society for Precision Engineering  

This paper proposes a mathematical model of a feed drive system which consists of an AC servo motor and linear ball guides. Structural and viscous damping of the mechanical system, Coulomb friction of the bearings and torque saturation characteristics of the motor are introduced into the mathematical model. Identification method of the parameters for the proposed model is also discussed. Various responses such as frequency response, step response, circular motion and corner tracking motion were simulated by the proposed model. Experimental works were also carried out in order to compare with the simulation results. It was found that the actual motor torque curves of the feed drive system were well expressed by the simulation model, and the shape and height of quadrant glitches of the circular trajectory were simulated accurately. In addition, the relationship between the centripetal acceleration of circular motion and the heights of quadrant glitch were investigated.

DOI： 10.2493/jspe.71.633

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER SOC MECHANICAL ENGINEERS  

In this paper, a new modeling, and controller tuning method for feed drive systems is described. Typical feed drive systems consist of an AC servo motor, a ball screw, linear guides, and a servo controller. In order to design high performance systems, it is effective to make a model and analyze its behavior. In this study, a feed drive system is modeled by a vibration model with two degrees of freedom. Various kinds of motions are measured and simulated. The results of the experiment and simulation show that these motions are well simulated by the model. This means that the proposed model can accurately estimate the transfer function of the actual system. As a result, it is easy to design a controller based on the transfer function. The gains in the velocity control loop are calculated based on the partial model-matching method. Two PI and I-P velocity controllers are applied to the feed drive system. The step responses are then compared to each other. The position loop gain is calculated from the frequency response of the velocity control system. The proposed method is applied to an actual feed drive system, and it is confirmed that the proposed method yields comparable performance to the system designed by the conventional tuning way. Copyright © 2005 by ASME.

DOI： 10.1115/IMECE2005-80596

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Scopus

J-GLOBAL

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Language：English   Publishing type：Research paper (international conference proceedings)  

This paper describes the dynamic synchronous accuracy of translational and rotational axes in 5-axis machining centers. In this study, non-uniform 3-axis synchronous motion was investigated in order to estimate the dynamic synchronous accuracy. A dynamic model of the each axis including a rotary axis was developed, and the synchronous motion was simulated. The dynamic model mainly consists of a moment of inertia, friction forces, a velocity controller and a position one. As the results of experiment and simulation, it is clarified the developed model can express the experimental results accurately. In addition, a method that can improve the synchronous accuracy is proposed, and its effectiveness is verified by the developed dynamic model.

Scopus

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

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Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

Authorship：Lead author,　Last author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (bulletin of university, research institution)   Publisher：神戸大学大学院工学研究科  

CiNii Research

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

Authorship：Lead author,　Last author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)   Publisher：日刊工業出版プロダクション ; 1953-  

CiNii Research

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

Authorship：Lead author,　Last author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)   Publisher：日刊工業出版プロダクション ; 1953-  

CiNii Research

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (scientific journal)  

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)  

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Language：Japanese   Publishing type：Rapid communication, short report, research note, etc. (bulletin of university, research institution)  

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