Research On Geometric Error Modeling And Identification Of Machine Tools Based On Combined Targets

The vigorous development of the manufacturing equipment industry has made higher demands on the machining accuracy of CNC machine tools at this stage.However,the increase in the service life of the machine tool as well as the aging and wear of each component result in a decrease in machining accuracy.In order to maintain and improve the machining accuracy of CNC machine tools,an effective and low cost error modeling,detection and identification scheme is needed.Based on the microangle sensor and the L-shaped combined targets,this paper proposed a novel identification scheme for the geometric error of the three-axis machine tools.The main work done in this paper is as following:1.By comparing the mathematical modeling and error identification method of the geometric error of CNC machine tools at present,the general mathematical model of the three-axis machine tool is established based on the multi-body system theory.The three-axis machine tool with type of FXYZ is taken as an example,the influence of the L-shaped machining error,the combined target installation error and the placement error of the L-shaped target array on the measurement results is analyzed,and the general mathematical model is improved and optimized to make it can be applied.2.The 90° transposition method is proposed to realize the separation and decoupling of the squareness error of the machine tool and the L-shaped combined targets.On this basis,the L-shaped combined targets are placed on the XOY,XOZ and YOZ planes according to the pre-planned paths.The angle error is obtained by the plane detection result,and then the result of squareness error and the simplified comprehensive error mathematical model are used to solve the coefficients of the positioning error and the straightness error polynomial.Thereby,the detection and identification of all 21 geometric errors of the three-axis machine tool are realized.3.Taking the coordinate measuring machine as the experimental object,the highprecision laser interferometer monitoring result was used as the reference to complete the accuracy verification experiment.The result of the experiment shows that the detection and identification errors of the measurement system are: the angle error is within ±1.5″,the verticality error is within ±1.5″,and the positioning error and straightness error are within ±2μm.