Research On Geometric Error Modeling And Compensation Technology Of Crankshaft Integrated Measuring Machine

Crankshaft integrated measuring machine is a high-level CNC accurate measuring equipment based on the principle of coordinate measurement.With the advantages of high precision,high efficiency and many measurement items,it has gradually become the crucial detection equipment of crankshaft manufacturing enterprises.Different from the measurement ball used in the front end of the traditional coordinate measuring machine,the measurement blade is used in the front end of the measurement head of the crankshaft integrated measuring machine.When measuring the parameters of the crankshaft pin journals,the contact point changes continuously along the mother line of the front end of the measurement blade.The influence of geometric error of crankshaft integrated measuring system on measurement results is also different from that of traditional coordinate measuring machine.Thus,it is necessary to carry out geometric error modeling and error sensitivity analysis,which can provide some theoretical support for the mechanical structure design and error compensation of crankshaft integrated measuring machine.Firstly,starting from the system composition and measuring principle of the crankshaft integrated measuring machine,the topological structure of the crankshaft integrated measuring machine is described based on the multi-body system theory.The position of the measured points on the crankshaft pin journals in the reference coordinate system is deduced by using the homogeneous coordinate transformation theory.Finally,the spatial comprehensive error model of crankshaft comprehensive measuring machine is established.Secondly,in order to describe the influence of geometric errors on the detection accuracy of crankshaft integrated measuring machine,the global sensitivity analysis is carried out based on matrix differential method and normalization method.Combined with the relevant examples,the traceability of key errors which has great influence on the detection accuracy of crankshaft integrated measuring machine is realized.The results show that 6 of the 21 geometric errors of the crankshaft integrated measurement system have significant influence on the radial measurement accuracy,and the sensitivity accounted for 87%?92%.Thirdly,in order to study the influence of error compensation on the evaluation results of roundness and cylindricality error,the error evaluation program is compiled based on roundness and cylindricity evaluation of crankshaft pin journals.The error evaluation interface of the roundness and cylindricity is designed based on MATLAB software,and the evaluation and display of the measured data,the data after key errors compensation and the data after all error compensation are realized.In addition,a comprehensive parameterized modeling program is compiled for different types of crankshaft.By continuously recording the error between the actual measuring point and the theoretical measuring point,the data source is provided for the simulation test in the following paper.Finally,in order to verify the correctness of the error compensation model,multiple sets of test data are obtained by combining the orthogonal test of numerical simulation with Monte Carlo Method.The results show that the accuracy of roundness error can be improved to 80%?85%by compensating the key errors of the measured data,and the accuracy of cylindricity error can be improved to 78.5%?82.5%,which is consistent with the previous sensitivity analysis,and the correctness of the theory is fully verified.