Research On Thermal Characteristic Analysis And Thermal Error Modeling Of Spindle Assembly Of CNC Lathe

With the development of modern manufacturing industry,the shape and function of products are more and more complex,and the precision of parts is more and more demanding.This puts forward higher requirements for the processing accuracy of CNC machine tools for parts processing equipment.Thermal errors account for the largest proportion of errors affecting the processing accuracy of CNC machine tools,and heat for high-precision machine tools.Error has a greater impact on its processing accuracy.Spindle assembly is one of the important functional components of CNC machine tools.The thermal performance of spindle assembly has a very important impact on the final processing accuracy of machine tools.Therefore,it is of great significance to study the thermal characteristics and thermal error modeling of CNC lathe spindle assembly.Taking the spindle assembly of HTC2050i horizontal NC lathe as the research object,this paper calculates the heat generation and heat transfer of the heat source of the spindle assembly,combines the simulation analysis with the thermal performance of the spindle assembly and its important components,builds the spindle assembly thermal characteristic test-bed,establishes the thermal error model by using the data obtained from the experiment,and passes through.The experimental data are analyzed to verify the correctness of the thermal characteristic analysis.The main research work of this paper is as follows:(1)Referring to the domestic and foreign literatures on thermal characteristics and thermal error modeling of CNC lathe spindle assembly,this paper summarizes the research situation and current situation at home and abroad,and determines the research contents and methods of this paper.(2)This paper calculates and analyses the friction heat generation of the bearing,establishes the three-dimensional model of the spindle assembly and its components,solves the relationship between the heat generation and the rotational speed of the bearing by means of the motion analysis and force analysis of the bearing,analyses the heat generation inside the cylindrical roller bearing,compares and analyses the heat generation variation trend of the three bearings.It also provides data for heat transfer analysis of bearings.(3)The heat transfer model of double row cylindrical roller bearings is established by using the thermal network method.In view of the defect of one-dimensional heat transfer in the thermal network method,some improvements are made in the division of nodes.The steady-state temperature distribution inside the bearing at different rotational speeds is solved and analyzed.The influence of the gravity load on the circumferential temperature distribution is analyzed,and the data are provided for the simulation analysis of the thermal characteristics of the spindle assembly.(4)The thermal characteristics of the spindle assembly and its important components are simulated and analyzed,and the temperature distribution cloud,temperature variation with time and thermal deformation cloud of the spindle assembly and its components in steady state are obtained.The thermal offset of the spindle axis is further analyzed by the simulation results.(5)The thermal characteristic experiment of the spindle assembly is constructed.The temperature rise of the spindle box and the thermal deviation of the check rod are tested and analyzed.The experimental results and simulation results are compared and analyzed to verify the correctness of the theory.The experimental data provide the original data for the establishment of error prediction model.(6)The thermal error prediction model is established,and the data obtained from the experiment are optimized.Using the optimized temperature rise data and the test rod offset data,the thermal error prediction models in X,Y and Z directions are established respectively,and the accuracy of the thermal error model is verified.In this paper,the thermal characteristics and thermal error modeling of spindle assembly are deeply analyzed and studied,which provides a reference for the compensation of thermal error and the improvement of the processing accuracy of NC lathe.