Modeling And Experimental Study On Friction Torque Of Ball Screw Pair Based On Lubrication Analysis

With the continuous development of CNC machine tools and mechatronics equipment in the direction of high speed,high precision and high efficiency,the speed of its core transmission component-ball screw pair has been continuously increased,resulting in increased wear and temperature rise,and reduced its service life.The lubrication design of the ball screw pair can effectively reduce friction,wear and temperature rise,and the lubrication effect will directly have a greater impact on the value of the friction torque.However,domestic research on the formulation of the friction torque mathematical model of the ball screw pair and the lubrication performance is basically in a blank state.Therefore,this paper takes the GD2505-3-P4 ball screw pair as the research object,carries out theoretical and experimental research on the friction torque of the ball screw pair,and focuses on exploring the contact between the ball and the screw and the spiral raceway of the nut.The influence of regional lubricating oil film pressure,film thickness,temperature and shear stress distribution,and the simulation calculation of the viscous friction resistance produced by the lubricating oil;a new mathematical model for estimating the friction torque of the ball screw pair is proposed,and the correctness of the mathematical model of friction torque estimation is verified by experiments,and a certain theoretical basis is provided for the lubrication design and friction torque estimation of the ball screw pair.The main contents of this article are as follows:Firstly,analyzing the contact lubrication area of the ball and the screw and nut spiral raceway,and obtaining the mechanical and kinematic parameters of the contact lubrication area to provide input parameters for the next analysis;then,according to Hertz contact theory,the mathematical model of non-Newtonian fluid elliptical contact micro-thermal elastohydrodynamic lubrication is established by equivalent model of ball screw inside and outside,and the numerical solution is carried out to obtain the distribution of oil film pressure,film thickness,temperature and shear stress,and to explore the influence of load,velocity and rough surface characterization parameters on the lubrication performance of ball screw,The friction drag force caused by lubricating oil is calculated numerically.Furthermore,the mechanism of friction of the ball screw pair is studied to determine the main factors affecting the friction torque.Based on the research foundation of the predecessors,a new mathematical model for estimating the friction torque of the ball screw pair is proposed to carry out the numerical calculation of the friction torque.Finally,according to the friction torque measurement principle and test requirements,the overall mechanical structure of the ball screw test bench,the servo control system and the friction torque acquisition system are designed;according to the needs of the system,the required sensors are selected and function of them are described;and then setting up the friction torque measuring device of the ball screw pair.Then carried out the experimental research of the actual friction torque of the ball screw pair,collected the real friction torque test data,and compared it with the national standard of the friction torque of the ball screw pair to verify the correctness of the test device;then the friction torque test device is used to test the friction torque of the corresponding speed for many times,and the corresponding numerical estimation results are compared,which verifies the correctness of the mathematical model of the friction torque estimation of the ball screw pair proposed in this paper.