In manufacturing industry, CAM (Computer aided manufacturing) software is utilized to generate to tool paths for the CNC (Computer numerical controlled) machine tools. However, there are still many parameters requiring human decision. Especially in free form surface machining field, the diversity and complexity of the surface make it challenging to achieve both the surface quality and machining efficiency. In the proposed method the freeform surfaces are subdivided into different groups of patches according to the surface normal vector value. The neighboring areas on the freeform surface that approximately have the same normal vectors are clustered into one group of patch and tool path is generated on each patch. This method is implemented on a freeform surface model. The result of the proposed method is compared with the traditional tool path generation method and evaluated by the machining time.

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Tool interference causes damage to surrounding soft tissue in minimally invasive orthopedic surgery with a milling robot. The objective of this study is to avoid the collision of cutting tool with complicated shapes, and a novel approach of interference-free tool path generation is proposed: intraoperative modeling of tissues and interference-free tool path generation. A model is constructed by using a 3-dimensional optical position sensor. Based on the model, interference-free tool path is immediately determined by preliminary definition of evacuating direction. The effectiveness of the proposed method is evaluated with artificial models on the system that we have developed so far.

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The efficient machining of workpieces with a complicated shape has being increased in terms of realizing the products with compact design and sufficient functionality. 5-axis control machining is suitable to meet such a requirement since it can cope with machining these workpieces without removing them. At the time, it is very important to rapidly generate interference-free tool path. Thus, the study deals with 5-axis control tool path generation to machine such complicated workpieces on the basis of the area division method, where the interference area is divided into small areas. The validity of the method is demonstrated with simulated results.

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Complex product is usually decomposed into various levels subassembly at assembly planning stage to achieve efficient production. Adjusting directly design structure tree of product in digital system is an important way for rapidly partitioning various levels subassembly. However, assembly reorganization, such as adjusting and modifying design structure tree, is very difficult in commerce CAD systems for their rigid limitation of assembly model. In this paper, the assembly information was firstly introduced. An assembly relationship representing model based on Assembly Relationship Element(ARE) was proposed, which associates flexibly assembly relationship information with hierarchical structure information. Organizing and storage mechanism of assembly information in assembly file were also presented. Based on analysis of reorganizing modes, dynamic management methods of assembly information in assembly files during reorganizing structure tree were proposed in details. Case study of universal transmission machine was finally given in digital assembly prototype system to verify the above research results.

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In order to provide technical supports for designing a new type of spiral plate forming machine, FEM analysis and simulation were carried out based on pressing tests. Deformation, stress distribution, residual stress and spring back of the spiral plate were calculated. Relationships between the spiral pitch to inclination angle of the punch and die, material properties and thickness of the plate were analyzed. A data converter was developed and effectively used in the analysis. The results of FEM analysis and simulation have been applied to design the spiral plate forming machines.

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This paper presents an improvement of design efficiency of machine tool structure in the stage of conceptual and basic design. An interactive system has been developed for designing machine tool structure. The distinguishing point in this system is that several conceptual beams are used to compose the total structure of machine tool because it is easy to analyze the static, dynamic and thermal properties. By converting the beam structure into an actual structure, the conceptual and basic design is completely finished. Consequently, the use of the interactive system allow, the designer to complete structural design of a machine tool in a shorter time with higher efficiency.

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In the present study, the shape of an object is first obtained from photographic images using the Photometric Stereo Method, and the target object is subsequently made from artificial material that resembles wood. The output gradient on the surface of the target object is limited to 67 degrees, but without needing to generate CAD data, using Rapid Prototyping (RP) is expected to decrease both the time and costs associated with prototyping. We propose a new method to obtain cutting location (CL) data in ball-end milling using the normal vector of object geometries generated by the Photometric Stereo Method

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While the usage of 5-axis machine has dramatically expanded, issues for application technology of 5-axis machine such as collision remain in practical use. Recently, the usage of Geometric simulation before cutting to prevent collision has prevailed in 5-axis and multitasking machine. However, collision accident when used manually still occurs, and both user and machine builder are highly focusing in collision free machining. In this paper, a development of on-line collision check system that is used by Geometric simulator and CNC openness is presented, and discuss the effectiveness.

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Multi-tasking machine tools are very useful to manufacture complicated workpiece efficiently. However, it is very difficult to generate NC data when an operator uses multi-tasking machine tools. Currently, there are some CAM systems for multi-tasking machine tools. However, there are such problems as the manual allocation of parts to generate tool paths, the difficulty of self-interference recognition without a simulator, and so on. Therefore, this study deals with the development of CAM system which can recognize part configurations, calculate tool paths automatically for turning and milling operations, and sort them in machining order, based on 3-D CAD data of work pieces.

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A new evaluation method of geometrical accuracy based on the evaluation of the machined workpiece has been developed. The strategy of our evaluation utilizes coordinates measuring machine (CMM) as a master gauge because of its accuracy so that machine operator devote himself to machining and estimator of accuracy dedicate in measurement. In our study, the non rotational machining is applied to realize the proposed evaluation. Machining error except the geometric accuracy of a machining centre is neglected by setting the cutting condition not to affect the desired machined workpiece previously. The measured results are enough accurate compared with those by the square master gauge calibrated previously. In this report, the machining setup and the evaluated results are shown with the experimental procedure.

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Recently, life cycle assessment (LCA) has been attracted attention in the manufacturing fields. Although some consumption devices have been designed taking LCA into consideration, to date there have been few reports on machine tools that do so. In this study, a desktop-size multifunctional machine tool is assembled for use as a cell production system, and we use LCA to estimate the environmental impact. The LCA results demonstrate that the use of smaller machine tools is an effective way to lower the environmental impact in small-parts manufacturing fields.

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The rotating spindle stiffness measurement with a developed magnetic loading device is proposed in this research. The circumferential grooved tool is designed and manufactured for cutting down the eddy current which decreases the electromagnetic attractive force by the loading device. The spindle stiffness is measured in the condition that the spindle rotates at high speed with applying load to the circumferential grooved tool by the magnetic loading device. As a result, enough electric magnetic force is loaded to the tool and the displacement of spindle rotating at the high speed is measured.

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In this research, we propose the new measurement method of contact stiffness of the joint with different material combination based on the former established method for the joint with same material combination. As the results, we enabled to measure the real contact area of the joint with various material combinations considering the reflected level of ultra-sonic wave at the real contact area. Moreover, we enable to obtain the contact stiffness of single-joint interface from the contact stiffness of double-joint interface.

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Conventional collision prevention systems for machine tools such as collision-prevention functions on NC controllers are based on simulations using 3D models of work pieces that are made in advance. If the setting up of work pieces differs from the models, then collision accidents are unavoidable. Therefore, a collision prevention system with enhanced functions for detecting work-piece setting defects of machine tools by simulation based on actual conditions from NC controllers and measurement data of work-pieces using 3D laser scanning is proposed. This paper presents a discussion of the system concept, development of a prototype system, and evaluation of the system.

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In the present study, we dealt with a finishing machining plane surface by ball nose end-milling with a five-axis controlled machining center. The condition is a surface roughness constant of Rz 0.5 μm considering both feed and pick feed rates. In addition, this machining was performed under a constant angle between the tool and the workpiece. We propose a new method that reflects concentric circles as a method to evaluate the surface using a near-infrared radiation image. The setting of an appropriate amount of feed and pick was clearly necessary.

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The passive forces acting against the drive force are phenomenon that influences dynamical properties and precision of linear axes equipped with feed drives. Covers are one of important source of passive forces in machine tools. The paper describes virtual evaluation of cover passive forces using the cover complex model. The model is able to compute interaction between flexible cover segments and sealing wiper. The results are deformation of cover segments and wipers which is used together with measured friction coefficient for computation of cover total passive force. This resulting passive force is dependent on cover position. Comparison of computational results and measurement on the real cover is presented in the paper.

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This paper describes a model of knowledge-based system for integrating CAM and CNC operations. In detail, the main concern of integration is driven by proposed standardized check list as a part of product data which is useful for capturing and managing the knowledge based activities done by CAM operators and CNC machine operators in assessing product data before proceeded into CNC machining process. With regard to the technical limitation concern, this system is focused on common CNC milling operations.

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Most machining tools are controlled by numerical control (NC) programs in order to achieve unmanned machining operations with high precision and improved productivity. However, all the movements of the machining tool are predetermined, and all instructions coded in the NC program are performed sequentially. Therefore, since the cutting process is not adaptable during unmanned machining, the cutting conditions should be set conservatively to avoid cutting difficulties. In the present study, machining strategies for adapting the cutting process during a milling operation to avoid tool breakage and to stabilize cutting load have been integrated into an autonomous NC machining tool developed under the Digital Copy Milling (DCM) concept. Successful endmilling experiments verified the effectiveness of the developed machining strategy.

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The frequent change in tool attitude makes the quality of machined surface worse. In the study, the influence of the change in tool attitude is evaluated, based on the experiment. Then, an evaluation formula is proposed, considering the influence of both the tool attitude and the change in tool attitude against the machined surface. Machining experiments are performed to confirm the validity. Moreover, the method that generates appropriate tool path for finish machining is devised by utilizing the evaluation formula. It is confirmed that the tool path generation method is useful to improve the quality of machined surface.

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In case of drilling for a large number of holes, the total process time is composed of the sum of the movement time between a hole and another, and the sum of the drilling time of holes. The former movement time depends on the drilling order although the latter drilling time is constant. The total processing time is largely dependent on the drilling order. Thus, the CAM system to generate the appropriate order for drilling a large number of holes with arbitrary direction is developed in this study.

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This paper describes a method for measuring the geometric deviations inherent to five-axis machining centers with an inclined A-axis and a rotary table. The inherent deviations are defined same as the machine with a cradle type table, if the inclination angle of the A-axis is an initial value. Mathematical expressions between geometric deviations and the center offsets of the trajectories were derived. The procedure for identifying the deviation using the expressions was described, and also the expressions can be applied to the cradle type. In addition, validity and the application limit of the proposed method are clarified.

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In this report, measure box shape is introduced as a test piece shape for the standard for testing five-axis machining center's accuracy because its accuracy is easy to be evaluated by squareness, flatness and dimensional accuracy. The test result shows that the correct length and diameter of the ball endmill is most important factor that affects the test piece accuracy, and therefore the test methods by using ball endmill is a little difficult to introduce to the test standard for checking the pure machine accuracy.

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This paper proposes a new method of evaluating the accuracies of 5-axis machining centers from workpiece machining tests. An array of grooves is machined on the workpiece while changing the rotation angle of the tilting table. From the created groove-matrix, the influences of the geometric deviations inherent to 5-axis machining centers, of the geometrical profile of the cutting edge of a ball end mill and of the tool length compensation errors on the machined surfaces are visible. The effectiveness of this proposed test has been experimentally verified.

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In this research, a compact desktop machine tool with polar-coordinate is proposed. Based on its polar-coordinate configuration, two rotational axes and one linear axis, it provides a higher flexibility than the traditional 3-axis machine tools. By using a hotwire cutter as the cutting tools, it could rapidly machine a fine product from a CAD model. Furthermore, by changing the tools into a touch probe sensor, it could also precisely measure the shape of a 3D object. With the versatile CAD/CAM software, which was specially designed for this Polar-coordinate desktop machine tool (PDMT), this system could fulfill various tasks, such as measurement of 3D objects, reconstruction of 3D models, machining of 3D parts, and even duplication of 3D products.

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This paper describes one of calibration methods of geometric deviations inherent to multi-tasking turning centers with a swivel tool-spindle head. Simultaneous four-axis motion and five-axis motion can be reduced the measurement number and time as compared with the simultaneous three-axis motion which needs six measurements. The proposed four and five-axis motion techniques require three measurements changing the test conditions. As the results, four-axis motion is superior to five-axis motion from the view point of the identification accuracy. However, if the errors such as pitch error of worm-gear exist in the measured trajectory, the accuracy of a few deviations is considerably deteriorated.

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There exist a lot of things difficult or impossible to create even by multi-axis control CNC machine tools. The study presents the first trial of creating an artistic workpiece by use of a multi-tasking machine. As an example, a chain-shaped workpiece is selected, which cannot usually be machined in the conventional manner. Thus, a special type CAM system is developed, taking account of the interference between a cutting tool and a workpiece, and the use of the second main spindle. As a result, it is found that the developed CAM system has the potential of artistic machining.

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In recent multi-axis controlled machine tools, to realize both high productivity and fine surface, a planning method to keep dynamic synchronous accuracy among tool axes and tool posture against local surface of workpiece is required. So, in this paper, we propose a new planning method based on integrated main/post processing system for tool posture. In the proposed method, movable range of rotational axes without collision and tool posture against local surface is illustrated as M-Map image for each cutting point with GPU. Then, by referring these images, continuous change of rotational axes keeping the tool posture can be planned.

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The study deals with an automatic measurement and evaluation system for thickness of free curved plates. In the study, a workpiece is handled by an industrial robot to measure thickness. A measurement path is automatically generated by the system without external data. The operator is just required to attach the workpiece to the robot and leave it for several minutes. Measured data is displayed according to the demand of operator -2D map display, 3D isometric display, etc. From the experimental result, the system found to be effective to get distribution of thickness with high density in a short time.

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In order to increase motion accuracy of NC machine tools, their feed drive systems are required to minimize the errors caused by control delay and friction. In this research, we analyze the errors and propose a compensation method using a reference model. In the method, the contour error is reduced by tuning the response of the reference model according to the desired accuracy level. Moreover, a friction-compensating method using the state of the reference model is introduced. The effectiveness of the proposed method on improvement of the motion accuracy is examined by an experiment.

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A design concept for highly dynamical micro milling machine tools is introduced. It intends lighter and more compact frames by compensating the dynamic dislocation. For this, the machine tool drives are used in combination with NC integrated real time simulation of the machine tool. The Dynamic dislocation is increased by a compliant design of the machine tool frame. This leads to a dislocation with lower dynamics making compensation accessible. The process dynamics of micro milling are analyzed and a test bench for proof of concept is described, showing, that the dynamic dislocation can be reduced extensively.

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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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In this study, we developed parallel link mechanisms by using multi-drive linear motors. Kinematics, dynamics, and control method of a three-degree-of-freedom (xyθ) planar parallel link mechanism with four redundant moving parts (3D4M mechanism) were investigated. A prototype of the 3D4M mechanism, which has decoupled dynamic characteristics, was developed. A notable kinematic characteristic of this mechanism was observed: the forward kinematics equation can be easily obtained by this mechanism. Workspace impedance control achieved by a force command was implemented in the prototype using a DSP based real time controller. Experimental responses of free vibrations to impedance control were compared with corresponding theoretical responses.

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This paper presents an approach for torque error compensation in an oscillating rotary pneumatic actuator. It is difficult to control the output torque of a pneumatic actuator precisely because of typical non-linear factors such as dead zone and pressure fluctuations in a pneumatic system. Thus, we proposed a hybrid actuator system which is integrated with an oscillating rotary pneumatic actuator and a voice coil motor (VCM) so as to compensate torque error in the pneumatic system by the VCM. Driving experimental results confirmed that the torque error in the pneumatic system is compensated by the VCM. Consequently, the hybrid actuator achieves high driving accuracy.

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The nano-motion control system of multiple degrees of freedom positioning in large travel ranges has been required in the field of precision engineering. In order to realize such a system, it is necessary and indispensable to develop a planar motion table system based on a new design concept. This paper presents a newly developed X-Y planar nano-motion table system with large travel ranges. This system is composed of a fine motion table and a coarse motion mechanism. Performance evaluation results confirm that the developed table system has a remarkable performance which includes nanometer positioning capability over large travel ranges.

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Intelligent machine tools require the functions of high-accurate process monitoring and adaptive control to fit the optimum process condition in each workpieces. For realizing these functions, the various techniques to monitor the cutting process and control it using additional sensors have been proposed and widely studied. Authors propose the sensorless cutting force control method using parallel disturbance observer. The performance of our proposed method is evaluated through simulation and experiments using a linear motor driving table.

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This paper reports on a new compensation method that is built on system of thermal transfer functions. Due to their relative simplicity they enable real-time calculations which make them suitable for compensation algorithms of thermal displacements at tool centre point. The applicability and robustness of the thermal transfer function compensation model have been experimentally verified on a real machine tool. Tested compensation algorithms proved its ability to significantly reduce thermal error. The thermal error minimization of more than 85% of the standard compensation technique based on linear regression model was achieved in particular coordinate direction.

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This paper describes electrical discharge machining (EDM) with a five degrees of freedom (5-DOF) controlled maglev local actuator. To machine microholes to a depth of more than the stroke of the maglev local actuator, a conventional EDM machine and the maglev local actuator were cooperatively controlled. To avoid abnormal electrical discharge, control of the jump and orbital motions by the maglev local actuator was evaluated. Experimental results showed that high speed and high precision re-positioning of the electrode by the maglev local actuator was effective for high speed EDM. Moreover, controlling the jump and orbital motions increased the machining speed.

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