Research On The Thermal Characteristics Of Spindle Assembly And Bearing For CNC Lathe

As an industrial machine,CNC machine tools directly determine the industrial level of a country.With the proposition of "Made in China 2025",China's manufacturing industry is developing rapidly,and at the same time,higher requirements are imposed on the machining accuracy of CNC machine tools.Error control of machine tools is an effective way to improve the machining accuracy of CNC machine tools.The error caused by thermal deformation of CNC machine tool is about 40%?70%of the total error of the machine tool.The spindle assembly is an important function of the machine tool,and the error caused by heat generation cannot be ignored.This article takes the HTC2050i horizontal CNC lathe spindle assembly as the research object,studies its thermal characteristics and its impact on the performance of the machine tool,and focuses on the thermal characteristics of the bearings in the spindle components.The bearing power consumption model,temperature field prediction model,and finite element simulation model of heat transfer were established.The frictional power consumption of the bearing,the steady-state temperature distribution,and the transient heat transfer process between components were analyzed.Based on the analysis results of the bearing,a finite element simulation model of the thermal characteristics of the spindle assembly was established,and the steady state,transient temperature distribution of the spindle assembly and its components,and thermal deformation caused by temperature rise were analyzed.The experimental platform for the thermal characteristics of the bearing and lathe spindle assembly was set up.The heat generation data of the bearing,the temperature rise data of the spindle assembly,and the thermal offset data of the spindle axis were collected through experiments to verify the theoretical and finite element analysis results.The main research work of the paper is as follows:(1)Consult the relevant literatures on the analysis of bearing thermal characteristics and the analysis of thermal deformation of the spindle assembly at home and abroad,summarize the research status and latest progress at home and abroad,and determine the research direction and content of the subject.(2)Establish a theoretical analysis model of the thermal characteristics of the spindle bearing.Comparative analysis of frictional power consumption of bearings in the spindle assembly.The finite volume method is used to establish the temperature prediction model of the double-row cylindrical roller bearing in the spindle assembly,and the change rule of the bearing temperature distribution with the rotation speed is analyzed to provide a theoretical basis for analyzing the thermal deformation of the spindle assembly.(3)A finite element simulation model for the temperature field of a double-row cylindrical roller bearing is established.A three-dimensional model of the bearing was established,and the dynamic heat transfer process of the double-row cylindrical roller bearing was analyzed by the finite element method.By extracting key points,the temperature distribution trend of the bearing was analyzed,and the theoretical results were compared with the theoretical results to verify the theoretical results.(4)Establish a finite element simulation model of the thermal characteristics of the spindle assembly.A three-dimensional model of the spindle assembly was established,and the steady-state thermal analysis,transient thermal analysis,and thermal-structure coupling analysis were performed on the entire spindle assembly using the finite element method.Based on the simulation results,the thermal offset trend of the spindle axis was analyzed.(5)Construct the thermal characteristics experiment of bearing and spindle assembly.The bearing experimental bench was designed and built,the bearing temperature data was measured,and the temperature change law of each area of the double-row cylindrical roller bearing under different preload forces and different speeds was compared and analyzed.The existing CNC lathe is used to measure the temperature change trend of each measuring point of the spindle assembly at different speeds of the spindle,and the thermal offset and offset angle of the spindle axis in the three directions of X,Y,and Z.The theory and finite element simulation results are compared to verify the feasibility of the theory and finite element model.This paper studies the thermal characteristics of the spindle assembly and its bearings,and provides data support for thermal error modeling and compensation of CNC lathes.Provide a reference for improving the accuracy and robustness of error compensation of CNC lathes.