Multi-error Comprehensive Analysis And Compensation Research Of Lv-850 Vertical Machining Center

With the development of precision manufacturing technology for CNC(computer numerical control)machine tools,there are higher requirements forward in the various manufacturing fields for the machining accuracy of CNC machine tools.Machining accuracy has become one of the important factors to the quality of a machine tool.Based on the theoretical analysis,and the combination of field test and simulation,a research object LV-850 vertical machining center is studied.Under in-depth study on the mechanism of the main errors of CNC machine tools,a multiple error factors impact model is established,the corresponding error compensation assumption is put forward after measurement and analysis.Finally,the error compensation experiment is carried out by using the comprehensive compensation model proposed in this paper.The main research work of this paper includes the following aspects:(1)Research on various error sources that affect the machining accuracy of CNC machine tools,and then the original geometric error,thermal error and error caused by machine tool force as the main influencing factors are determined.The comprehensive mathematical model of geometric error,thermal error and force error is established,which is the foundation for the identification,simulation and modeling of multi error elements of machine tools.(2)The three-dimensional geometric model of the machining center is set up and the thermal error characteristics of the whole machine are analyzed by using ANSYS Workbench.The results show that the main heating points of the machine locate on the spindle,slide block and screw nut,which can be used as a reference for selecting the optimal thermal key points of machine tool in the next temperature measurement.The finite element analysis results of thermal deformation can be used as a reference for thermal error compensation too.(3)Based on the fast and efficient detection principle of laser interferometer and ballbar,the geometric error of each moving axis in the machine center is measured.The test of thermal positioning error of the machine center is designed,and the positioning error curve of each axis under different temperature is obtained.Through analysis,it is found that there is a certain relationship between the slope of the trend line of each error curve and the temperature,which provides a theoretical basis for the establishment of the thermal geometric integrated error model of the machine center.(4)Based on the theory of polynomial least square method,the measurement data is treated,and the correlation function of each error is obtained.The function has a good fitting accuracy which satisfies the requirements of error compensation.Finally,according to the comprehensive error compensation model,the compensation module of FANUC 0i system is used to compensate the thermal positioning error at any time,and the compensation effect is remarkable.The result shows the model built in this paper is practical,and it has an important theoretical significance for improving the machining accuracy of machine centers.