Research On Degradation Mechanism And Evaluation System Of Ball Screw

Ball screw is widely used in precision machinery, automation, semiconductor and other fields with its high precision, efficiency, rigidity and stability. The working performance and transmission accuracy decline gradually which leads to failure ultimately. It always leads to great economic loss. So it is very important to evaluate the performance status of ball screw pair in real time.Based on contact mechanics, collision mechanics, elastohydrodynamic lubrication theory, it analyzes the influence of the structure parameters on the contact angle, pressure and deformation and establishes load distribution model. It analyzes the axial stiffness of the ball screw pair system. Then it studies the movement of the ball in the work roll and the inverter. Based on the analysis of the source of friction torque and influencing factors, the theoretical model of friction torque is established.Considering the influences of load, rotating speed, lubrication, temperature and error, the performance degradation mechanism under different working conditions is revealed. Then the paper determines the evaluation index of the performance state. This paper focuses on the application in the NC machine. In order to monitoring the performance condition effectively and conveniently, with reducing the use of the sensor, the study establishes an indirect measurement method of the evaluation index.To evaluate the performance status of ball screw pair in NC machine, the paper uses NC machine equipped with SIEMENS 840 D CNC system as the application object. Based on OPC data services, the study develops the performance evaluation system for real-time monitoring of ball screw pair's performance state, which can reduce the economic loss caused by ball screw performance degradation.