Error Analysis And Experimental Research On Hybrid Grinding And Polishing Machine Tool For Blade Finishing

With the development of manufacturing industry and technology,People’s requirements for the machining accuracy and overall performance of the machine tools are getting higher and higher.The static and dynamic characteristics of the machine tool itself,such as motion accuracy,rigidity and vibration resistance,affect the whole performance of the machine directly and then affect the precision of the machined parts.In this paper,the geometric errors affecting the machining accuracy of the machine tool are modeled and analyzed,and the experimental modal analysis of the hybrid grinding machine tool is also studied,which provide theoretical guidance for processing and subsequent error compensation,So as to provide powerful help for the development of China’s equipment manufacturing industry.According to the basic theory of experimental modal analysis,the experimental modal analysis of the hybrid polishing machine tool and its main substructures are studied.The excitation signal is knocked by a hammer with force sensor,and the sampling frequency between excitation signal and response signal are set to be different during the modal experiment.The ERA method and LSCF method are used to identify the modal parameters respectively and then compare the results,from which the lower natural frequencies,damping ratios and modal shapes of the whole machine and its main substructures are obtained.Based on the analysis of frequency and vibration mode,it is concluded that the crossbeam is the weak link of the machine tool,and some suggestions for improvement are put forward.The geometric error model of serial and parallel part of hybrid machine tool are modeled with different modeling methods respectively.In this paper,I explain the advantages and disadvantages of the two geometric error modeling methods,multi-body system modeling method which is suitable for simple series structure and Matrix differential theory modeling method which is suitable for complex parallel structure.Establish the spatial error model for the series structure based on the multi-body system theory.And then establish the spatial error model for the parallel structure of the hybrid machine tool based on the Rodrigues parameter description method and the matrix differential theory.All errors of each part in the 3-RPS parallel mechanism are set to be a specific number according to the shape error tolerance class 6.The numerical simulation is carried out to analyze the influence of the geometric errors of the mechanism on the positioning accuracy of the blade fixture on the moving platform.At the same time,the positioning accuracy of the blade fixture is simulated when the error value of a single part is changed from the value 6 tolerance to the 7 tolerance to find the greatest impact error of 3-RPS parallel mechanism in machine tool.For the study of the spatial error distribution of the series part,firstly,the errors of X and Y axis of the hybrid machine tool are measured by the laser interferometer.Secondly,bring the geometric errors into the series geometric error model of the machine tool.Then the regularities of spatial error distribution is obtained by numerical simulation under the condition of X and Y axis linkage.The spatial error distribution of the X and Y axis in the working area is obtained by MATLAB.The spatial error is analyzed by selecting a specific trajectory of the machine tool.By comparing the distribution and the changing trend of the geometric error of X and Y axis,the influence of each error on the synthetic error is obtained.Then,the proportions of positioning errors,straightness errors and other errors to the synthetic error are obtained through numerical calculation.As for the research on error distribution of the parallel part,firstly the positioning error of A,B,C electric cylinder are measured by using the displacement sensor.Then a set of specific trajectory is selected and brought into the error model of the 3-RPS parallel mechanism.The error distribution of the trajectory is calculated,which provides guidance for the subsequent error compensation of the machine tool.