Research On Dynamic Error Traceability Of Five-axis CNC Machine Tool Based On Hierarchical Clustering Analysis

The detection of dynamic contour error of five-axis CNC machine tools is of great significance for improving the performance of machine tools and the quality of processing.Nowadays there is no international standard for testing performance of five-axis CNC machine tools.Based on this situation,Chengdu Aircraft Industrial Co.,Ltd proposed the S-shaped test piece with abundant characteristics which is used to assess the performance of five-axis CNC machine tools.Since it had the ability to detect various performances of the machine tool,S-shaped test piece have been in the final draft stage of international standards.However,due to its complex structure,curvature and twist angle of S-shaped test piece,the theoretical basis and research of some error mechanisms still lacked sufficient theoretical basis.Therefore,based on the S-shaped test piece,the aim of this paper is to study dynamic contour error in milling process and the corresponding error trace.The details are as follows:Based on the electromechanical structure of the five-axis CNC machine tool,the corresponding servo drive system was established.The PID control model,servo motor model and mechanical structure model were built by the software Simulink,and the speed feedforward controller for improving system accuracy was introduced.After the geometric model of the S-shaped test piece was established,the tool axis vector code required for processing the S-shaped test piece process was obtained by the SPO algorithm.the dynamic contour error generated during machine tool milling process was obtained by the discrete method.Based on hierarchical clustering analysis and multiple linear regression,a traceability method was proposed.The error set were gathered by hierarchical clustering analysis method optimized by genetic algorithm.And the position loop gain,the dynamic stiffness of the machine tool and the feedforward parameter were obtained by multiple linear regression methods throughout milling process.The real processing experiment was designed reasonably,and the results of simulation and traceability method analysis were verified by analyzing experimental results.