Research On Integrated Error Modeling And Identification Method Of Double-turntable Five-axis Machine Tool

Five-axis machine tools will be affected by many factors during the machining process to produce machining errors,among which geometric errors and thermal errors account for more than other types of errors in the entire machining error.It is of great significance to analyze and decouple several geometric error items and thermal error items included in the geometric error and thermal error to clarify the specific values of each error item,It is of great significance to improve the machining accuracy of machine tool by error compensation in later stage.Tuopu VMC-C50 double turntable five-axis machine tool is the research object of this paper.Firstly,after analyzing the specific structure of the machine tool and establishing the corresponding coordinate system,the position and attitude of the moving parts of the machine tool are described by matrix based on the theory of multi-body system,and the geometric error model of the five-axis machine tool with double turntable is established.Secondly,based on the finite element theory,a thermal simulation model was established for the main heat-generating components of the Tuopu double turntable five-axis machine tool.Combined with the finite element model,the specific positions of the temperature measurement points that need to be arranged in the thermal error measurement experiment are clarified,which provides a theoretical reference for the smooth development of the thermal error experiment.Then,the temperature measurement points of the main heat-generating components such as the spindle,turntable,guide rail and lead screw of Tuopu double turntable five-axis machine tool were optimized by using the theory of clustering algorithm,and several temperature sensitive points were obtained by analysis.According to the temperature change data and displacement deformation data at the temperature-sensitive points of the main heat-generating parts of the machine tool measured by the thermal error measurement experiment of the machine tool,the thermal error model of the Tuopu dual turntable five-axis machine tool was established based on the multiple linear regression theory.The corresponding thermal error value can be calculated after inputting the temperature change into the thermal error model of the machine tool,and the compensation of the thermal error of the machine tool can be completed by modifying the CNC machining code of the five-axis machine tool,which lays the foundation for the individual identification of the geometric error of the machine tool.Finally,through the analysis of the two kinematic chains of the Topu doubleturntable five-axis machine tool,the comprehensive error model of the doubleturntable five-axis machine tool is established based on the homogeneous coordinate transformation.Then,based on the in-machine measurement results of the "S" shaped specimen,the specific values of several geometric error elements were obtained by identifying and calculating the error elements of the two rotating axes A and C of the machine tool,and a number of geometric error and thermal error elements were calculated by the comprehensive error model.By comparing the calculated results,the accuracy of the synthetic error model and the feasibility of the synthetic error identification method based on the machine measurement of "S" shaped specimen are proved.