Research And Analysis On The Thermal Performance Of Ball Screw Feed System

For high-speed and high-precision CNC machine tools,the thermal characteristics of the key components of the machine tools will have an important impact on the final performance of the machine tools.Therefore,it is of great significance to study the thermal performance of ball screw feed system to improve the positioning accuracy of CNC machine tool feed system and the manufacturing level of CNC machine tool.In this paper,thkbnf1610 ball screw feed system is studied.Firstly,the mathematical model of ball screw theoretical analysis is established,and then the steady temperature field distribution of ball screw is calculated;Secondly,the finite element model of the ball screw feed system is established,the thermal performance of the feed system is analyzed,and the mathematical model is verified;Finally,the actual temperature and deformation of the ball screw feed system are obtained through the thermal characteristic experiment,and the mathematical model and the finite element analysis results are verified.The main research work of this paper is as follows:(1)Based on the review of the relevant literature about the thermal characteristics analysis of ball screw feed system at home and abroad,this paper summarizes the research status and the latest progress of the thermal characteristics of ball screw feed system at home and abroad,and determines the research direction and research methods of this paper.(2)The movement of the ball in the ball screw nut pair is analyzed.The contact deformation and contact stress of the ball are obtained by Hertz point contact theory.The friction torque model of the ball screw is established by analyzing the friction of the ball.Through the relevant parameters in the above analysis,the heat and boundary conditions of each heat source of the ball screw feed system are analyzed and calculated,which provides the basis for the subsequent theoretical model establishment and simulation analysis.(3)Based on the basic law of heat conduction and the finite difference method,the discrete equations of the screw shaft are constructed,and then the theoretical analysis mathematical model of the ball screw is established.According to the results of the mathematical model,the steady-state temperature distribution of the screw section is analyzed,and the comparison of the screw with or without raceway characteristics is made by using the mathematical model,and the influence degree of raceway characteristics on the analysis of the thermal characteristics of the screw is obtained.(4)The three-dimensional model of the external circulation ball screw nut pair is established.The influence of different ball size and different load on the local steady-state temperature of the ball screw nut pair is simulated and analyzed.The thermal characteristics of the external circulation ball screw nut pair are obtained.The three-dimensional model of the ball screw feed system is established.The static structure analysis,the steady and transient analysis of the temperature field and the thermal structure coupling analysis are carried out,and the overall temperature field and deformation field are obtained.(5)The experiment platform of ball screw feeding system is constructed,and the experiment of temperature rise and thermal deformation of ball screw feeding system is realized.The trend of temperature rise and thermal deformation of ball screw feeding sy stem under different operating speed and different table load is obtained,and the influence of different working conditions on the temperature and thermal deformation of ball screw feeding system is analyzed.The experimental results are compared with the theoretical mathematical model results and the finite element simulation results to verify the feasibility of the theory and simulation analysis.In this paper,the temperature field distribution of ball screw is determined by the established theoretical mathematical model.The influence of different ball sizes and different ball loads on the local temperature of screw nut pair is analyzed by the finite element simulation.The influence of different working conditions on the temperature rise and thermal deformation of ball screw feed system is analyzed by the finite element simulation and experiment,which is helpful for the further study of ball screw feed system The thermal characteristics provide the basis for the thermal error compensation of ball screw feed system.