Dynamic Characteristics Analysis Of Ball Screw System Of High Speed And High Acceleration Cnc Machine Tools

In recent years,ball screw feed system is not only used in the mechanical industry,but also in the defense industry,such as radar,missile and aerial refueling aircraft.With the development of global economy and technology in recent years,ball screw pairs are gradually developing towards high speed,high precision and heavy load.Among them,the development of ball screw pair to high-speed direction is to meet the needs of high-speed cutting machine tools.The cutting speed of cutting edge of high-speed cutting machine tool relative to the surface of parts is 5-10 times higher than that of normal cutting.The spindle speed and feed speed of high-speed cutting machine tool are very high.Then,for high-speed machine tools,the highest spindle speed,the fast forward speed of feed system,the high acceleration and high deceleration of feed system are the important technical indicators of the machine tool.At present,due to the immature technology,the ball screw pair is not suitable for high speed,especially high acceleration.On the one hand,under high acceleration,the moving parts of the machine tool will produce a large inertial force,which will change the actual contact state of the flexible parts of the feed system and the joint parts of each rolling pair,resulting in the change of contact stiffness,thus affecting the dynamic characteristics of the feed system.On the other hand,it is almost impossible to eliminate the exciting force during the operation of the ball screw.The exciting force is generated by the rolling and circulating ball between the screw shaft and the nut.The higher the feed speed is,the greater the exciting force is.These forces usually act on the screw shaft and cause the resonance of the screw shaft.Therefore,it is of great significance to study the dynamic characteristics of CNC ball screw feed system under high acceleration for improving the overall performance of CNC machine tools.The main contents of this paper are as follows:First of all,under the support of domestic and foreign literature,combined with the investigation practice,deepen the understanding of ball screw feed system,grasp its structure characteristics,working principle,create a theoretical model and analyze the time-varying vibration characteristics of the ball screw system under the support of relevant theories.Secondly,the simplified physical model of the ball screw feed system is established in UG software,and then it is introduced into Ansys for simulation analysis,and the vibration mode of the ball screw feeding system is obtained,and the force and deformation of each part of the ball screw feeding system under external load.Through the analysis of the simulation results,the maximum force position and the maximum deformation position of the ball screw feeding system are obtained,from the theory for the ball screw feed system to improve performance,design level to play a guiding role.Then,based on the dynamic model and mathematical model of the system,the time-varying vibration characteristics of the system are analyzed by MATLAB software.Thirdly,the equivalent dynamic model of the high acceleration ball screw feed system is established,the critical acceleration of ball screw is simulated and analyzed by using MATLAB software to explore whether the critical acceleration will be affected by the total load mass m,nut position Y,screw tensionF_as and rated dynamic load P,and how the acceleration affects the system transmission stiffness and kinematic pair stiffness.Finally,taking the experimental platform of ball screw feed system as the research object,the influence of table position on the natural frequency of the system is studied.After comparison,the reliability of theoretical modeling and simulation analysis is verified.In this paper,the dynamic characteristics of the ball screw feed system are analyzed,the modal analysis and static analysis of the system are carried out,the time-varying vibration characteristics of the system are analyzed,and the influence factors of the critical acceleration of the system are analyzed,which provides a theoretical reference for the development of the feed system of high-speed CNC machine tools.