Study On Thermal Error Modeling Of Feed System Of Precision Machine Tool Considering Structural Thermal Deformation

With the rapid development of precision machining technology,the influence of thermal errors on the accuracy of machine tools becomes more and more important.Feed system is one of the main heat sources of machine tool.In order to reduce the influence of thermal error of feed system,this paper synthetically considers the coupling effect of temperature field and thermal deformation field of machine tool structure-feed system,and studies the simulation,modeling and detection of thermal error of machine tool structure-feed system.The distribution of temperature,thermal deformation and thermal error of machine tool feeding system under different working conditions is analyzed,which provides a reliable simulation analysis and experimental method for the control and compensation of thermal error of precision machine tool feeding system.In order to systematically study the formation mechanism and influencing factors of thermal errors in the feed system of precision machine tools,the heat source,heat transfer and thermal deformation law of large parts in the structure of precision horizontal machining center are analyzed firstly.By studying the influence of thermal deformation of structure on thermal deformation of ball screw and grating ruler,a thermal error modeling method of feed system considering thermal deformation of structure is proposed.This method takes into account the mechanism of the endogenous heat source-cooling system affecting the temperature rise and thermal deformation of the key parts of the feed system,and the influence of the endogenous heat source of the feed system on the thermal characteristics of the large parts of the precision machine tool structure.By analyzing the change of the relative position of the motor seat and the bearing seat of the feed system caused by the thermal deformation of the structure,and the change of the absolute position of the grating ruler,respectively.A semi-closed-loop model and a full-closed-loop model for thermal error of feed system considering thermal deformation of large part-lead screw and large part-grating ruler are established.In order to verify the above model,taking a precision horizontal machining center as an example,the thermal error simulation analysis and modeling of feed system considering thermal deformation of structure and not considering thermal deformation of structure are carried out,and the corresponding test and verification experiments are carried out.The results show that the temperature simulation model and error model established in this paper are in good agreement with the experimental results.The thermal deformation of the structure has an important impact on the thermal error of the feed system.The research results of this paper provide a new idea for the thermal error modeling of the feed system of horizontal machining center.The thermal positioning error modeling of the feed system under different working conditions can be realized by using this method.The results show that the thermal error simulation results of the feed system considering thermal deformation of the structure have a higher coincidence with the experimental results.It is of great significance for evaluating and improving the thermal characteristics of the machine tool during operation,designing the thermal balance of the machine tool structure,controlling and compensating the thermal error of the feed system.