Influence Factors Analysis On Machining Accuracy Of Five-axis CNC Machine Tools And Error Tracing Based On The S Shape Test Specimen

Five-axis CNC machine tool is a very complex system.There are many factors affecting the machine tool's machining accuracy,including geometric factors,dynamic factors,thermal factors and force factors.These factors have a common influence on the cutting precision of the machine tool.In order to improve the machining accuracy of five-axis CNC machine tools,it is necessary to carry out accuracy testing and error tracing.The S test specimen is more and more widely used in precision detection.The advantages of the S test specimen are that it can well reflect the linkage of five-axis machine tools and comprehensively reflect the processing performance of the machine tools.In the error traceability based on the S test specimen,since the mapping function between S test specimen and Five-axis CNC machine tools' procecing error is complex,the error-tracking theory still needs to be improved.Comprehensive evaluation is a management cognitive process that is widely used in the fields of economy,society and education.This paper evaluates the machining accuracy of the machine tool through the comprehensive evaluation method,and traces the machining error of the machine tool with poor accuracy.The research work of the dissertation is as follows:1.Establish the motion error model of CNC machine tools.Based on the classic PID model of control theory,a control model for the translational axis and rotational axis of a five-axis CNC machine tool was established.Combining the dynamic model of movement axis,the feed servo system model of each axis was established.Adding force factors and geometric errors complete the model of the machine tool,and use particle swarm optimization algorithm to optimize the machine tool's servo system to improve its dynamic response.2.Analyze the influence of various factors of the five-axis machine tool on the machining precision of the S test specimen.Five-axis machine tools are classified and the topological structure chain of each type of five-axis CNC machine tools is established.Kinematic analysis is employed for different topologies of the machine tools.Taking a CA-type double-swinging five-axis CNC machine tool as an example,the effects of dynamic factors and geometric errors on the machining error of the S test specimen are simulated and analyzed.3.Evaluate the accuracy level of the machine tool.Under the framework of comprehensive evaluation theory,the factors affecting the machining error of the machine tool are extracted,and the extracted factors are stratified by the corresponding affiliation relationship to establish the index system of the machine tool.Using the Analytic Hierarchy Process(AHP)to determine the weights of each factor in each layer of the system,the final accuracy of the machine tool is obtained.4.Tracing machining errors in machine tools with poor accuracy.The comprehensive evaluation method is used to obtain the membership degree vector and the weight vector,and the factors influencing the machining accuracy of the machine tool are sorted so as to trace the processing error.Improve the traceability software and guide the debugging of the machine control panel parameters based on the results obtained by the traceability software,which is used for the acceptance and accuracy improvement of the machine tool.