High-speed Ball Screw Performance Analysis And Experimental Study Of Friction

Precision ball screw is a key machine tools of CNC. With the development of high-speed cutting technology, there are higher and higher requirements for the speed of the ball screw line. High-speed ball screw brings about a temperature rise caused by friction, serving as a main constraint to the improvement of its speed. Therefore, it's of great theoretical and practical significance to provide theoretical and technical support in solving the heating problem of high-speed ball screws by researching the effects of high speed on its contact characteristics and transfer efficiency, analyzing the mechanism of friction torque, and establish equations on the analysis of friction torque.Considering the helix angle, this thesis applies Hertz contact theory to analyze the contact characteristics of balls and the raceway. Using the static equilibrium of ball screws, establish the transfer efficiency equation through consideration from three aspects: the sliding friction of ball and the raceway, rolling friction and the combination of the two mentioned above. Then, analyze the change after increasing the screw helix angle by considering the contact stress, axial elastic deformation and transfer efficiency. And prove the model validation with the use of theoretical calculations, finite element simulation and experimental methods.According to Hertz contact model and the Principles of Tribology, analyze the mechanism of ball screw friction torque. Establish ball control in the reverse model of the friction torque based on Theorem of kinetic energy of particles. Besides, establish the ball screw friction torque model deputy considering the effects of contact load and speed on the friction coefficient, as well as different load and speed on the friction torque. For the analysis of how Friction torque will affect the heat of the screw, establish an equation on the relationship between friction torque and the screw temperature rise using principles of heat transfer. Finally, prove the model validation of the friction torque by measuring the different temperatures of ball screws at different speeds and periods of time.