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.
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.
Unexpected glitches typically 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-nosed end milling tests of hemispheres and its finished surface simulations with different geometric errors and different position loop gain of feed drive systems were carried out, in order to clarify the influence of the geometric and dynamic synchronous 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 rotary axes changed rapidly.
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.
This study concerns famous places appearing in the Miyako Meishozue (An Illustrated Guide to Noted Places in the Capital), the spatial construction involved in the illustrations contained therein, and the image Akizato Ritō, the editor of the work, sought to convey. Were 4,000 copies printed, as Takizawa Bakin asserts in his Ibun zakkō? A study of the illustrations contained in the Miyako Meishozue was conducted concerning these points.
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.
This study compares the motion characteristics of 5-axis machine tools with Japanese and European NCs under wing profile machining. Productivity is one of the most important factor in the industrial field. It is known that the cycle time of the machining process typically depends on the manufacturer, control mode, and setting of the NC controllers, even though the identical cutter path is applied. In order clarify the influence of the manufacture and control mode of the NC controllers onto the cycle time and velocity profile of the machining, wing profile machining tests are carried out by 5-axis machining centers with different type of NCs. Identical CL data is used for the tests. Effect of TCP control mode on to the cycle time and velocity profile is also investigated. As the results, it is clarified that the TCP control mode can significantly reduce the cycle time. In addition, it is clarified that the jerk is limited when the European NC is used although the acceleration is limited in case the Japanese NC is used.
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.
