The Contact Deformation Research Of Ball Screw Pair And Temperature Field Analysis Of Its Drive System

As a drive mechanism with less energy and high precision, ball screw has many excellent characteristics of high efficiency, high precision, high speed and wear resistance, it has already aroused a wide range of attention and application home and abroad.Ball Screw is the key part of NC machines and it plays a significant role in improving sensitivity, positioning accuracy and so on. In particular, the contact characteristics of ball screw and thermal expansion has a direct impact on the the positional accuracy and repeatablity precision of machine tools. So we should first start from the structure of ball screw pair and analysize its contact characteristics in order to reduce the influence of contact deformation of the ball screw on the machine accuracy. Meanwhile, because ball screw drive system produces a lot of heat due to the friction torque, it is necessary to analysize the temperature field distribution of ball screw drive system.The research of ball screw in this paper can be summarized in four aspects as below:(1) Based on the principal curvature formula of ball screw pair, analyze the relation curve of helix angle, contact angle and the principal curvature. The increase of helix angle and the contact angle can effectively improve the contact characteristic of ball screw.(2) Based on the Hertz Contact Theory, establish the mathematical model to solve the contact deformation of ball screw pair. Make the deformation curve and the stiffness curve of ball screw pair with Matlab. And obtain the relation curve of helix angle, contact angle and deformation, and set up a FE model to prove the validity of the theory with ANSYS.(3) According to the design specifications and operating conditions, choose every part of drive system. Check the speed stress and maximum load of ball screw drive system and establish the model with PROE.(4) Set up a simplified model of ball screw drive system, and calculate the friction torque of various parts.Derive the thermal boundary conditions and load them in the FE model, make the thermodynamics temperature field steady-state analysis of ball screw drive system. According to finite element analysis result of temperature field, the amount of thermal expansion can be calculated to determine the pre-tension force of ball screw drive system.