Research On Key Technologies Of Comprehensive Error Compensation For Five-axis CNC Machine Tools

As the "working machine" of the equipment manufacturing industry,the machining accuracy of CNC machine tools directly restricts a country's industrial level.In order to improve the machining accuracy of CNC machine tools,the key technologies involved in the geometric and thermal error compensation of machine tools,included error detection and identification,error modeling and compensation system development,are studied..The main work of this paper is as follows:(1)Taking the QLM27100-5X five-axis machine tool as the research object,the geometric error element identification model of the moving axes is established based on the 9-line method,and the error element identification models are respectively established for the motion modes of A-axis and C-axis.the geometric errors of the moving axes and the rotating axis are measured by using laser interferometer and ball bar instrument respectively,and the respective geometric error elements are identified.(2)Aiming at the complexity of factors affecting the thermal error of the machine tool,the modeling method of the thermal error of the moving axis is studied.Based on the Grey Relational Analysis,the temperature measuring points are optimized.Based on the algorithm of Support Vector Regression machine,the positioning thermal error model of the moving axes are established.Compared with the traditional Polynomial Regression model.(3)The topological structure of a five-axis machine tool is described using the low-body array of a multi-body system.The error matrix of each kinematic pair of the machine tool is established based on homogeneous coordinate transformation,which realizes the calculation of tool space position error.Based on this,an error compensation algorithm of multi-axis linkage is discussed based on the idea of error cancellation.(4)Combined with the temperature compensation function of the Siemens 840 D CNC system,a comprehensive error real-time compensation system is designed and developed.Through the geometric error compensation experiment of the C-axis and X/Y-axis linkage and the comprehensive error compensation experiment of the moving axes,the results show that the error accuracy of the machine tool after compensation is improved by more than 50%,which verifies the effectiveness of the compensation system.