Dynamic Behavior Research Of Steel Baking/Composite Liner Nut

Screw transmission transforms rotation motion into straight-line movement, which always played an important role in people’s lives. Screw-nuts as the key part of screw transmission, researches focus on improving precision and load capacity, to achieve efficient, heavy-duty and precision transmission. Steel backing/composite liner nut. taking steel as housing to enhance the load capacity, and taking composite that has excellent anti-friction and wear resistant performance as lining material, would not only minimizing friction loss, but also helpful to improve dynamic performance, weaken even eliminate of stick-slip. Screw-nuts composed of Steel backing/composite liner nut and screw, combine the advantages of both tradition sliding metal spiral screw-nuts and ball screw-nuts, and overcome both disadvantages, directing an import way for researching of efficient, heavy-duty and precision transmission screw-nuts.This paper studied Steel backing/composite liner nut. Transition behaviors from static to kinetic friction, influences of sliding velocity, normal load, and materials composition on friction and dynamic behaviors were investigated. Built simulink diagram of sliding friction system, researched the effect of drive speed, system rigidity, and the deviation of static friction force and kinetic friction force. Based on classic stribeck friction model, a new friction force model was built. Compared with experience measure data, the new friction model was proved be efficient for predicting friction coefficients of composite materials at low speed. Then a physical model for Screw-nuts was built. Dynamic differential equation was created, which conjunction friction model and physical model of Screw-nuts. Based on the equation, the dynamic analysis was on process, and studied the stick-slip of screw-nuts.Designed and built a plane slide experimental set-up, which could measure static and kinetic friction coefficient at low speed (below1mm/s), making up for tribotester’s shortage of couldn’t test static friction coefficient, and show the transition behavior from static to kinetic friction in curve. Stick-slip was observed with load370N and at velocity1.2mm/min. Experiment results showed that the difference between kinetic friction coefficient and static friction coefficient is smaller when the weight ratio of MoS2to graphite is2:3.Through study this material deeply, it was found that, composite sample has better friction property than bronze (ZQSn10-1) sample, and its friction force depended on sliding speed, which fits stribeck friction model. The static fiction coefficient is nearly equal to the kinetic friction coefficient of the composite sample when it was lubricated. Designed and set-up screw transmission measurement apparatus. Influences of different loads(0-475N).velocities(3-30r/min).dry friction and lubrication were invested. It found that increased load could enhance the stability of transmission, and speed play a key role on the dynamic behavior of screw-nuts. When speed decreased to3r/min. stick-slip would appear even no load. Meanwhile lubrication has a significant impact on screw-nuts’friction behavior. Through position curve and torque curve under the same conditions, it was found that friction torque of composite nut is smaller than copper nut (QSn6-6-3). In all. Steel backing/composite nut has better friction and dynamic behavior than copper nut.