Research On Key Technology Of Ball Screw Pair Pre-stretching For Minimum Thermal Deformation Of Screw Shaft

Thermal deformation is the biggest source of error that affects the machining accuracy and positioning accuracy of CNC machine tools.As a key functional part of CNC machine tools,controlling ball screw shaft thermal deformation is the key to improving the accuracy of CNC machine tools.Screw pre-stretching,as an efficient and easy-to-operate thermal deformation compensation technology,is widely used in the field of CNC machine tools,but currently the pre-stretching amount is mainly based on experience,and there is no systematic research.This article takes the national science and technology major project as the background.Firstly,the theoretical model of the pre-stretch and thermal deformation of the ball screws is established.Then the finite element analysis and experimental verification of the theoretical model are performed.Finally,the ball screw under different working conditions is established.Quantitative calculation method of auxiliary pre-stretch amount.The specific work is as follows:(1)Firstly,the influence of the pre-stretching amount of the ball screw pair on the thermal deformation is analyzed,and then the relations between the pre-stretching amount and the pre-tensioning force,the pre-tensioning force and the friction torque,and the friction torque and the thermal deformation are derived.Finally,a theoretical model of the thermal deformation of the ball screw based on the pre-stretching amount was finally established.(2)Based on the theoretical model of the thermal deformation of the ball screw,combined with Abaqus software,a finite element simulation of the thermal deformation of the screw shaft was performed,and the change of the pretension force of the screw shaft under different pretension amounts was analyzed,And draw the temperature and thermal deformation cloud images of the screw shaft.(3)A comprehensive performance test system for a portable ball screw is constructed.The shortcomings of the comprehensive performance test bench of the ball screw pair cannot be moved.The measurement of vibration,temperature rise,and positioning accuracy of the ball screw pair by CNC machine tool manufacturers has been achieved.(4)Based on market demand and user feedback,a test plan that meets actual measurement requirements such as vibration,temperature rise,and positioning accuracy was developed.Pre-tension tests under different models and installation methods were completed at the CNC machine tool manufacturer,and the tests were verified The feasibility of the method and the reliability of the data.By comparing the experimental data with the theoretical model,the method for determining the optimal pre-stretching amount of the ball screws with the minimum thermal deformation under different working conditions was finally obtained,which provided a theoretical basis for the ball screw pre-tensioning.