Test Equipment Design And Research On Friction And Wearing Experiment Of Linear Ultrasonic Motor

Program resources of this paper: Supported by National Natural Science Foundation of China(50 75136),Natural Science Foundation- Key Program of Guangdong Union Foundation(U0934004) and Major State Basic Research Development Program of China(2011CB707602).Linear ultrasonic motors are known for their various advantages such as direct actuating, stepping and servo working, as well as excellent controllable performance. Hence, linear ultrasonic motors are becoming increasingly important in the studying field of ultrasonic motors around the world. As the output characteristics of ultrasonic motors are directly influenced by the friction characteristic and wear of the interface between stator and promoter, it is necessary to study the tribology between stator and promoter of the linear ultrasonic motor. The main accomplished work is as follows:Friction and wear test device for linear ultrasonic motor was manufactured based upon its working principle. With this device, the relationship between the wearing rate of stator driving foot and the preload of linear ultrasonic motors, the relative motion velocity of contact point of promoter was studied. Friction characteristics of driving foot interface were also analyzed in this paper. Furthermore, wearing capacity of friction pair was tested by electronic analytical balance, wear rate was calculated and friction surface was analyzed as well. The driving foot and stator used in the test were made of 45 steel and alumina ceramic respectively(45 steel). The results of the test indicate that the friction coefficient increases (decreases) as pre-pressure (relative speed) increases, and wear rate of the stator increases (decreases at first and then increases) while preload (relative speed) increases. The wear mechanisms of the stator are brittle flaking off and fatigue wear. Moreover, abrasive wear is the major reason of stator wearing, while adhesive wear and fatigue wear are minor reasons.The friction coefficient of the friction pair of stator and 45 steel goes through a process during which it grows from small to big and gradually approach to a stability state. The wear rate of the stator grows with the load when the velocity of the friction is low, and further more when the load is bigger, the friction rate has an obvious increase. The wear rate increases at first and then decreases when the load increases. The major wear mechanisms are abrasive wear,adhesive wear and oxidative wear. And the contact mechanics model of the linear ultrasonic motor is also studied by the methods of classical Hertz contact model and fractal theory separately.