Axial Dynamic Stiffness And Experimental Research Of High-speed Overloaded Ball Screw

Ball screw is widely used in all electric injection molding machines and other automated machinery as a precision linear drive component. But under high-speed and overloaded condition, transmission performance of the ball screw becomes poor. So on this basis, this dissertation is to discuss and research the dynamic stiffness of ball screw.This dissertation is composed of the following parts:In the first chapter, introduce the research background and significance, and summarizes the characteristics and development of the ball screw.Then give the primary contents of this dissertation.In the second chapter, analyze the influence factors of axial dynamic stiffness of the ball screw, supporting form, preloaded, preload force, structure parameters, motion parameters, friction and lubrication impact stiffness of the ball screw. Comprehensive considering all aspects of factors, establish axial dynamic stiffness model of ball screw.In the third chapter, considering impact load and centrifugal force effect in the actual work process, establish the ball screw dynamic force model. Using the speed relationship between nuts and screw, get the acceleration relationship. The contact stress formulas and contact stiffness formulas of the nut side and screw side are deduced by using Hertz stress formula, and then using numerical example to shows that how the structure parameters and the motion parameters and the gap influence ball screw elastic contact deformation.In the fourth chapter, based on all electric injection molding machine Molmerged Institutions, testing ball screw position precision under high-speed overloaded operation. Using axial dynamic stiffness model of ball screw, calculate unit step response, then transform measured displacement data which can get form Grating feet into the unit step response, contrast experiment data with theory data, prove stress formula and dynamic stiffness model are correct. And then according to the relationship between stiffness and frequency, analyze how the speed and acceleration influence the stiffness.In fifth chapter, summarize the main research results, emphasizes the paper's innovation, and further research work is prospected.