Multi-functional Composite Machine Tool Error Measurement And Modeling Technology

Under the major strategic deployment of "Made in China 2025",China's manufacturing technology has made rapid progress.The characteristics of high speed,high precision and complex functions have become the development trend of machine tools.The general NC machine tools whose processing accuracy can not be guaranteed can not meet the needs of manufacturing industry.In order to further improve the processing accuracy of machine tools,it is necessary to analyze the main factors affecting the processing accuracy of machine tools,and to solve this problem is an urgent matter to meet the requirements of the development of manufacturing industry.This topic takes multi-functional compound machine tool as the research object,and carries on the measurement and modeling analysis to the error of X,Y,Z axis and spindle of machine tool.The main contents and achievements of this paper are as follows:(1)The geometric and thermal errors of the motion pairs and spindles of the compound machine tool are analyzed,and the comprehensive error elements of the compound machine tool are sorted out.The geometric error transformation matrix of the moving pairs and the rotating pairs of the compound machine tool is derived by means of homogeneous coordinate transformation technology,which lays a foundation for the next comprehensive error modeling.(2)Establishing the comprehensive error model of compound machine tools.Based on the coincidence principle of tool tips and workpiece points to be machined,a comprehensive error model is established,and the mathematical expressions of error components in x,y and Z directions are derived.(3)Measuring and modeling the geometric errors of moving axes.Based on the nine-line error separation principle and laser interferometer,the geometric error elements of X?Y and Z axes of machine tools are measured and recorded.The geometric error elements of X?Y and Z axes of machine tools are modeled and analyzed by polynomial fitting principle,and the mathematical expressions of movement error components and rotation error components of machine tools' comprehensive geometric errors in x?y?z directions are derived.The results show that when the polynomial order m = 3,the positioning accuracy of the x?y?z axes of the moving axes is improved by more than 70% and the angular error accuracy is increased by more than 75%,which proves the validity of the model.(4)Measuring and modeling the thermal error of machine tool spindle.The temperature sensor is used to measure the spindle temperat ure of machine tool.The improved fuzzy C-means clustering algorithm is used to optimize the selection of temperature measurement points.The selected key temperature points are modeled by multiple linear regression.The results show that the residual valu es in the y and z direction of the spindle are within 5.4 ?m after multiple linear regression modeling.