Contact Mechanics Simulation And Static And Dynamic Analysis Of Ball Screw

The Ball Screw is a key component of the CNC precision's feed system.due to its performance such as high accuracy, high stiffness, little friction, etc .it is widely used in CNC machine, precise machinery, and other related high-precision fields. The performance of it impacts on CNC machine's positioning accuracy and repeatability positioning accuracy directly, thereby affecting the accuracy of working CNC machine. Studying the feed system of Ball Screw, in particular ball and return tube collision of the working process, the contacting deformation of ball and the spiral groove ,and static and dynamic characteristics. We can design and use the Ball Screw to improve the guidance, which has important significance in promoting high-precision machinery's development.This topic analyzes the balls'force and the elastic contact in the groove of the Ball Screw, researches static and dynamic characteristics of the Ball Screw, and makes some analysis about the contact between the balls and return tube, Based on Hertz contact theory and collision mechanics. The main content is as followed:(1) The development and research status of the Ball Screw is analyzed, the importance of researching of Ball Screw is indicated. working principle, characteristics and structure form of Ball Screw are described in detail.(2) The movement and mechanical characteristics about the balls in the spiral groove of Ball Screw are systematically introduced. Meanwhile the ball's rotation and revolution speed, slip characteristics are researched. the elastic contact of Ball Screw's nuts and roller screw is analyzed by using of Hertz contact theory. A simplified finite element method is adopted to analyze the model of the stress, strain and contact stress. Analysis shows that the roller ball and screw ball and the contact pressure are greater than the contact pressure roller nut. Therefore, the wear of screw roller groove is greater than the wear of nut roller groove during working. This provides the basis for the structure design and material selection of Ball Screw. (3) The changing rule of the Ball Screw's strain and stress analyzing with the strut ways is systematically reviews. and the theoretical models is compared through the ANSYS finite element analysis. The conclusions are that both ends of the Ball Screw's axial deformation is a parabolic variation, one end of the fixed support of the Ball Screw's axial deformation is linear growth, both ends of the fixed support means'axial deformation is minimal, both ends of the fixed support means'axial stiffness is the best.(4) The modal analysis method is introduced and the problems and solutions about overall modeling process of Ball Screw are described. the whole of Ball Screw is though modal analyzed by using the finite element software ABAQUS and HyperMesh. which calculates natural frequencies and mode shapes about Ball Screw after three different strut ways, and discusses the application situations of different strut ways. Modal analysis results reflect the structure's dynamic characteristics and provide the basis for design, evaluation and use of Ball Screw.(5) The contact theory model about ball collision with return tube is established, and the main influencing factors of impact force are analyzed. the ball collision model is made to take dynamic simulation by Using CATIA and ADAMS. the collision force of a ball, two balls and four balls with return tube is partly analyzed, the impact of collision force is discussed during the different materials and different inlet velocity. Through the simulative research to balls and return tube's impact force, we can see that the impact force of bend return tube is relatively large, the greater inlet velocity the impact force is greater, the impact force is increasing as the material density's increases. Therefore, the design of return tube and the optimization of bend radius are the key elements for future research.The result of this topic provides a theoretical basis for design and use of Ball Screw. and provides appropriate technical support for our self-developed precision Ball Screw, thus, the result has an important significance to improve the precision of CNC machine tools and high level manufacturing equipments.This thesis work is being funded by international cooperation and communication special project of The Ministry of Science and Technology, the project name is"The technology and euipment of micro/nano scale complex surface cutting processing".