Research On Coupling Compensation Control Of Contour Error In Five-axis NC Machining

The five-axis machine tool is a processing device composed of two rotating axes on the basis of the three-axis CNC machine tool.When the five axes are linked,the position of the tool tip and the attitude of the tool axis can be adjusted at the same time.Aircraft structural pieces,precision abrasive tools and other complex curved surface parts.Mastering the processing technology of five-axis CNC machine tools has a very important supporting role for the development of China’s aviation,military,scientific research,and high-precision medical equipment.Five-axis CNC machine tools are relatively complicated in the process of machining parts.The tracking error caused by various factors is an important reason for the contour error caused by coupling.The contour error will affect the final machining accuracy of the part.In order to effectively reduce the contour error,the research on the control of the contour error is carried out.In this paper,three kinematic models of BC double swing head,double turntable and swing head turntable are established,and the mathematical formula of RTCP algorithm is derived through coordinate transformation.Taking the B-swing head C rotary table five-axis machine tool as the research object,the machine tool simulation model is established in Vericut,and the NC code of the "S" test piece generated by Power Mill is used for simulation verification.The verification results show that the formula deduced in this article is correct.The contour error model of the tool tip position and the contour error model of the tool axis of the five-axis machine tool are established,and the effects of each feed axis of the five-axis machine tool on the two contour errors are analyzed.An open control system was used to build a five-axis machine tool test platform,and the "S" test piece was processed to verify the effectiveness of the RTCP algorithm and two contour error calculation models,and to analyze the impact of the error.The influence of the rotation axis position on the translation axis position is analyzed.Based on the two contour error calculation models,a contour error compensation method is established.Based on the cross-coupling control idea,a decoupling compensation method is proposed,which compensates to three Set up a simulation model on the moving axis and two rotation axes.The transfer function used in the simulation model is measured using the software PMAC Analyzer.The results show that the established compensation method effectively suppresses the contour error.Based on the above basis,the compensation controller is used to compensate the actual reference input value of each feed axis,and the iterative learning controller is used to modify the actual reference input value to further improve the tracking accuracy of each feed axis of the five-axis machine tool and reduce the contour of the part processing Error,and use the multi-parameter optimization function of genetic algorithm to adjust the PID controller parameters,and simulation verification.The results show that the iterative learning control method can further reduce the contour error of the five-axis machine tool.