Study On The Static And Dynamic Characteristics Of A Friction Drive Micro-Feed Mechanism

As one of the fundamental technologies in the field of high-tech, ultra-precision machining has become a supporting technology of science and technology. Precision and ultra-precision machine tools play a crucial role in researching ultra-precision machining. Nowadays, micro-feed mechanism is more and more widely used in the field of ultra-precision machining to achieve accurate micro-displacement, and it has already become a key technology in the field of ultra-precision machining. The motion characteristic of a micro-feed mechanism is decided by its static and dynamic characteristics, so it is necessary to study its characteristics. The static and dynamic characteristics of a micro-feed mechanism using friction drive are studied in this dissertation. In this paper, theoretical foundation for developing a micro-feed mechanism with large stroke and high resolution has been provided.The micro-feed mechanism presented in this paper is a friction driven-type precision mechanism which is capable of high positioning accuracy. It consists there parts. The first part is the friction driven actuator using PZT elements. The second is the transmitting mechanism composed of ball screw and coupling. The third is the static-pressure air-bearing guide way which is used for supporting the work table. The static characteristic of the micro-feed mechanism is studied in this paper. The rotary inertia, driving torque, rigidity of the driving chain and the equivalent rotary inertia of the micro-feed mechanism are obtained by analyzing and calculating.To research the dynamic behavior of the micro-feed mechanism, system modeling is performed and the dynamic equations are obtained. Stick-slip phenomenon during the course of friction driving is investigated. And dynamic modeling is performed by using Karnopp stick-slip friction model. The factors that affect the positioning resolution of the system such as positive pressure, friction coefficient, parameters of driving voltage and rotary inertia are investigated by simulation. Conclusions are obtained and reasonable span of each parameter are given.Finally, experiments are performed and problems during the experiments are studied. From simulation and experimental results, it is observed that the dynamic behavior of the simulation predictions agreed well with that of experimental results. This indicates that the model developed in this paper is capable of describing the dynamic behavior of the micro-feed mechanism, and the simulation results are credible and can be used to direct further study. What's more, the simulation and experimental results provide good foundation for the application of the micro-feed mechanism.