Synthesis Error Modeling And Compensation Research For Five-axis Polishing CNC Machine Tool

With the rapid development of science and technology to make fundamental changes in the manufacturing level, common CNC machine tools are gradually replaced by precision and ultra-precision CNC machine tool. The development and application of numerical control machine tool marks a nation’s industrial production ability and scientific and technological level, also is to realize the automation and intelligent manufacturing system, integration of the foundation. In this paper, based on the five-axis polishing machine tool as the research object, deeply analyzes the methods of error kinematics modeling and error elements measurement and comprehensive modeling principle and application of error compensation. The main research content as follows:(1)With detailed description of the movement structure of five-axis CNC polishing machine, analyzes the error source for each revolute pairs and sliding pairs of machine tool, lists out uppermost elements of the geometric error and thermal error of five-axis machine tools. Kinematics of the error motion for machine tools was analyzed with using the homogeneous coordinate transformation theory, it is concluded that the error motion transformation matrix of revolute pairs and sliding pairs of machine tools in the ideal condition and the actual condition.(2)To analyze the shaping movement of each axis of machine tool, according to the structure characteristics of the five-axis CNC machine tool movement, the machine tools can be divided into two kinematic chain: tool chain and work piece chains. Based on the homogeneous coordinate transformation theory, established the synthetic modeling of error movement mechanism for five-axis CNC machine tool from work piece coordinate system to tool coordinate system. According to comprehensive modeling to calculate the six terms volumetric error from tool coordinate system to work piece coordinate system of machine tool and to verify the validity of the synthetic modeling of error movement of machine tool.(3) Using laser interferometer to repeatedly measure and analyze the positioning error, two straightness error and two angle error of five-axis machine tools and to study the measured data deeply that get the change rule of each error element of machine tool.(4) The positioning error of CNC machine tools three mobile axis is measured according to the different time, at the same time, using PT100 temperature sensor to measure key position of the temperature for machine tools. According to the measured results, the positioning error of machine tool is a comprehensive error is verified. Considering the different characteristics of the geometric error and thermal error to make the error separation for the positioning error of machine tools, using Newton interpolation to built the geometric error modeling of positioning error of machine tools, based on analysis of grey theory, it is concluded that influences the temperature of the thermal error of machine tool is the most critical point, using the least squares algorithm to built the thermal error modeling of positioning error of machine tools, and then synthesizes the two models for a comprehensive error model. According to the comprehensive error model, based on error compensation module of the precision polishing machine tools in the system, error compensation experiments is made out, validity and effectiveness of the model is verified.