Research On Dynamic Characteristics Of High Speed Ball Screw Feed System

CNC machine tools are developing towards the direction of high speed,high automation and intelligence,which requires higher and higher dynamic performance of machine tools.Feed system is an important part of the machine tool,its dynamic characteristics have a significant impact on the machining quality and efficiency of the machine tool.In order to improve the machining quality and accuracy of the machine tool,research on the dynamic characteristics of the feed system has become a research hotspot of most scholars at home and abroad.In this paper,the feed system of a highspeed CNC lathe is taken as the research object,and the dynamic characteristics of the feed system are studied from the perspectives of theoretical modeling,finite element analysis and experimental verification.Firstly,based on the Hertz contact theory and the dynamic characteristics of the ball screw pair,the axial stiffness model of the joint is established,and the effects of velocity,acceleration,contact angle,helix angle and curvature ratio of raceway on the axial contact deformation are analyzed.The contact model of rolling linear guideway pair is established,the contact model of single ball and raceway is analyzed,the contact deformation curve of the joint is obtained,and the influence of external load on the deformation stiffness of rolling linear guideway under different preload is analyzed.A three-dimensional model of the joint of the ball screw and the rolling linear guide is established,and the static analysis is carried out by using the finite element method.The contact deformation analysis results are basically consistent with the theoretical analysis results.Secondly,combined with the stiffness parameters of the ball screw pair and the rolling guide pair,the equivalent model of spring damping element is used to deal with the rolling joint,and the finite element model of the ball screw pair,the bed saddle,the rolling linear guide pair and the whole feeding system is established.According to the theoretical basis of modal analysis and finite element method,the modal analysis of ball screw feed system and its main components is carried out,and the first 12 natural frequencies and corresponding modes are obtained.Finally,the test modal analysis method is used to hammer the ball screw feed system,and the test modal parameters of the ball screw feed system are obtained,and the correctness of the finite element analysis results is verified by comparison.Based on the analysis of dynamic characteristics of high-speed ball screw feed system,combined with the results of finite element analysis and modal test,the vibration reduction measures of ball screw feed system are proposed.