The Research On Improvement Of Pivotal Technology Of High-speed Ball Screw Dynamic Performance

With the development of mechanical drive systems in the direction of high speed,high precision and compound environmental protection,higher and higher requirements are imposed on the dynamic performance of the ball screw at high speed.The anti-vibration performance of the ball screw itself,the surface quality of the raceway,and the running condition of the ball in the return devices are also the main factors affecting the performance of the high-speed ball screw.Through the theoretical analysis of these factors,and to achieve some key technologies such as the innovative structure and processing method for improving the dynamic performance of the high-speed ball screw,it is particularly important to improve the design and manufacturing level of the high-speed ball screw.In addition,simply relying on increasing the speed to achieve high-speed drive will be limited by the limit speed data,and will seriously affect the ball screw vibration,noise,friction,temperature rise and many other performance.Under the same driving speed condition,the large lead ball screw can reduce the rotation speed,thus improving the dynamic performance.Therefore,the design and the manufacturing capability of the large lead screw becomes a key factor that restricts the dynamic performance of the high-speed screw.In this paper,the classical mechanics such as contact mechanics and collision mechanics are used,and the key techniques for improving the dynamic performance of high-speed ball screw are studied by simulation and experiment.(1)The movement and load bearing characteristics of the balls were analyzed.The influence of the structure and force position of the ball screw assembly on the force and distribution of the ball is analyzed.Based on the bearing of the ball screw and the deformation law of Hooke's law,the micro-variation of the pitch of the nut is explored to make the bearing and the distribution more well-distributed.(2)The characterization method and reduction measures of surface waviness are introduced.The influence of the waviness of the raceway surface on the ball motion is analyzed by mathematical model,and the influence of the waviness on the vibration of the ball screw assembly is listed.The paper introduces the causes of waviness and the control of waviness in detail.It is clear that the waviness can be passively reduced by grinding on the raceway using special tool.(3)I use the end-cap type(DK)4025 ball screw as the model,and use the software ANSYS-Workbench to analyze the modal of the ball screw using different supporting system.The variation of the natural frequency of the ball screws of different materials was studied.It provides a basis for the selection of the support mode of the high-speed ball screw and the structural optimization direction for improving the anti-vibration performance.(4)According to the theory of collision mechanics,the dynamics of the ball return process in the ball screw assembly is studied.For the collision of the ball at the entrance and exit of the returning device and the instability vibration caused by the sudden change of the curvature in the return ball hole.In this paper,a new return curve of end-cap type(DK)ball screw is proposed based on mathematical methods.The UG 3D design and software ADAMS is used to simulate the collision and circulation of the balls in the return device.The simulation shows the changes of the force and kinetic energy of the ball passing through the old and new returning devices.The results show that the uniformity and energy loss of the ball collision force are much better than the ordinary returning device,which is to promote the vibration noise of the screw and increase the smoothness of the ball.(5)The processing of the inner raceway of the large lead nut is often constrained by the machining ability.By comparing and analyzing the current inner raceway processing method and theory,based on the principle of gear meshing,it is proposed to mill the inner raceway by the disc milling method.The high-precision and high-efficiency processing method has been experimentally verified;the method can be extended to the turning and milling of the nut to realize the compounding and efficient processing of the nut.This paper introduces the research and application of the current advanced hardware turning raceway technology.In this method,the axial line of the cutter bar is parallel to the axial line of the nut,which breaks the limitation of the spiral angle to the processing;in addition,this type cutting process not only achieves high dimensional accuracy,but also is more environmental protection.