Position Geometric Errors Identification And Synchronization Analysis For 5-axis Machines Based On Double Ball Bar

The geometric error of the rotating axis of the machine tool has a great influence on the machining accuracy of the machine tool.The movement of the two rotary axes of a five-axis CNC machine tool results in an increase in the space error term,and the coupling of the rotary axis and linear axis errors in the measurement makes it difficult to measure and identify the errors.At present,there is no precise instrument that can directly measure the geometric error of the machine's rotary axis.This type of error mainly relies on indirect measurement and identification through mathematical models.Generally,the geometric error of the rotation axis needs to be measured and identified separately,but the operation requirements are high,the range of use is limited,and the efficiency is low.In order to improve the detection accuracy and identification efficiency of static geometric errors,a five-axis linkage measurement method based on a ballbar was proposed to realize the rapid measurement of the static geometric errors including the rotating axis,and it was gradually improved and related experimental research was carried out.This paper applies the theory of spin to mathematically model the structure of a BC rotary five-axis CNC machine tool,and analyzes and tests its 11 items of static geometric error detection and identification.Including Matlab simulation to verify the feasibility and effectiveness of this method.A reasonable spatial measurement trajectory is designed to realize the one-time identification of three verticality errors of the linear axis of a five-axis CNC machine tool,two parallelism errors of each rotary axis,and two position deviations.The orthogonal experiment design method is used to discuss the influence of the installation error and measurement posture of the club on the accuracy of the club measurement,to improve the details of the club test and error identification,and to further improve the measurement and identification method.The spatial trajectory comparison method is used to solve the servo mismatch between the linear axis and the rotary axis during the actual experiment,improve the accuracy of the ballbar error measurement,and provide favorable conditions for error identification.The method proposed in this paper can measure and identify static geometric errors of machine tools that are independent of motion position,has the characteristics of accurate and reliable identification,and good anti-interference,and can be widely appliedto the detection and identification of static geometric errors of machine tools and robots with rotary axis structures in.