Research On Dynamics Simulation Of High Speed Ball Screw And Structural Optimization

As the key component of numerical control machine tools, ball screws can be satisfied the high dynamic characteristics and control precision of CNC machining requirements, with advantages of little vibration, low noise, smooth operation and high reliability. With the high-speed development of manufacturing, CNC machine tools, machining centers tends towards high-speed, high-precision and intelligent, the performance of ball screw mechanism is demanded higher. By the ball, the ball screw achieved the transition from the rotation to linear of the mechanical transmission. The mechanical transmission process is more complicated, therefore, the ball screw have a physical limit in the positioning accuracy, drive speed and acceleration, etc. The value of dN indicates the safety rolling speed of ball in ball raceway and reverse device. When the screw speed exceeds the critical value, some problem such as the vibration, noise and temperature rising caused by friction become increasingly prominent. To meet the requirements of high-speed machining, the method improving the value of dN and the dynamic performance in ball raceway and reverse device is the key.In this paper, with the application of contact model, kinematics theory and multi-body dynamics simulation software ADAMS, through the dynamic simulation, study the dynamic performance of ball screws. The study contents are as follows:1) According to Hertz contact model, analyzing the contact stress distribution and contact deformation in raceway. Then discusses the effect of contact deformation on contact angle of ball screw. Finally, compared the difference of ADAMS contact model and the actual contact.2) According to kinematics theory, analyzing the ball movement feature in the raceway. Investigated the influences of structural parameters on self-locking and slipping phenomenon. And then, established dynamic simulation model.3) Using the multi-body dynamics simulation software ADAMS, analyzing the composing of friction torque, and establishing the method of ball screw flexibility assessment. Analyzing the impact ball track cross section geometry error, raceway manufacturing error and reverse installation error on friction torque.4) Considering the differences of ball screw and rolling bearings, established the mathematical model of ball screw drive efficiency. Discussed the impact of the contact angle, helix angle and the equivalent friction coefficient on transmission efficiency. By the vibration analysis, researching the wear of ball screw and providing the basis for fault diagnosis.