Research And Application On Kinematic Generic Modeling Theory For Five-Axis Machine Tool

For machining of complex shaped parts, five-axis linkage NC machining technology with its characteristics of high efficiency and precision, has been widely applied and promoted. Thorough research and development have been carried on by colleges and enterprises at home and abroad about five-axis linkage NC machining technology and its carriers—five-axis machine tools, and a relatively perfect technology and industry system has been formed. However structure of five-axis machine tools in practical use is of diversity, and considering the kinematic modeling of five-axis machine tools is one of important bases to carry out other research work, study on how to establish kinematic generic model and its applications is conducted in this article.Present method of kinematic modeling for five-axis machine tools with specific structure has a certain generality, but a kinematic generic model has not yet been established. The work-piece is chosen as the referenced body, and the structure of five-axis machine tools is described based on multi-body system (MBS) in this article. The homogeneous coordinate transformation matrix (HCTM) between two adjacent bodies is determined by parameters combination, and the kinematic generic model for five-axis machine tools is then established.The performance of machine tools is restricted due to existing methods of rotation angles solution, by which the stroke of C rotary worktable is limited. In this article, based on the kinematic generic equations of five-axis machine tools, the calculation method of rotation angles, in view of4types of five-axis machine tools with C rotary worktable and perpendicular configuration, is improved by defining "the minimum movement circle", and the range of rotation angles is expanded. Moreover, the calculation flow is determined, by which the rotating continuity of C rotary worktable is effectively improved and the interference is availably avoided. A specific post-processing program integrating the new calculation method is developed by using VC6.0.Workspace is one of indicators used in robotics to evaluate robot performance, and it is applied to describe five-axis machine tools in this article:the collection of positions and postures of cutting tools. Monte Carlo method is presented for workspace analysis process of five-axis machine tools. The kinematic equations of2kinds of five-axis machine tools are derived by using the kinematic generic model, and "clouds" reflecting the workspace of machine tools is acquired by simulation in MATLAB. Moreover, factors which affect the shape and location of workspace are analyzed.Based on qualitatively analyzing the reason of overtravel in the linkage machining process, methods of judgment and calculation for overtravel in the linkage machining process are presented by using the kinematic generic model in this article. The conclusion that cutter position and posture corresponded to each NC code are in the workspace of machine tools is not the necessary and sufficient condition of that machining can carry out, is verified.There are various types of error in practical machining process, in which geometric error of machine tools plays an important part. Based on the kinematic generic model, geometric error model of five-axis machine tools, considering geometric error, is established. The geometric error is compensated by software compensation method. The accuracy of geometric error model of machine tools is verified at a certain extent by compared machining experiment and measurement results.It can be stylized to establish kinematic model of five-axis machine tool with arbitrary configuration based on the kinematic generic model proposed in this article. The kinematic generic model is applied to rotation angles solution in post processing, workspace analysis, overtravel in linkage machining process and geometric error modeling, and some actual problems in the machining process are solved.