Reserch On Friction Characteristic Of Kinetic Surface Based On Ultrasonic Vibration

With the development of the science and technology, precision and ultra-precision machine have an important increasing position in the field of precision machining. However, the ultra-precision machine tool will appears phenomenon of stick-slip, when it works under the condition of low speed and heavy load, Ultra-precision machine tool can bring instability when there is stick-slip in low speed. Stick-slip can cause the guide rail movement non-uniformity, reduce positioning accuracy and the sensitivity, and induce the processing work piece surface quality fall. Simultaneously, friction and wear can cause the engine bed transmission system inactive. Much literature indicates decreasing friction parameters is an important method to eliminate negative effect of stick-slip. At the same time, it is effective measure to add ultrasonic vibration into friction pairs. It is social and academic significance to study ultrasonic antifriction.Moreover, ultrasonic vibration mainly has used in the cutting tool or work piece widely, the report which the application of ultrasonic in the guide rail or slide carriage has not seen. The study of kinetic friction coefficient based on ultrasonic vibration is short. Based on the Florida model and analysis of the real contacting from the point of view of adhesion, asperity ploughing and debris ploughing, between the friction pairs formed by grinding surface, the relation between coefficient of kinetic friction and surface roughness of surface is presented in this topic.For measuring the coefficient of friction, experience system which is based on ultrasonic vibration has been rebuild by designing measuring device of accelerated speed. The experience table is made up of two reversible platforms and is belong to a kind of measure based on gravimetric method. Displacement data of experience system have been acquired by optical grating and time data has been acquired by photoelectric switch and data acquisition card respectively. Processing program of data input and output has designed by soft of Visual Basic.In addition, experiment has been performed with this device to measure the kinetic coefficient of friction for three kinds of material under the condition of ultrasonic vibration. In the dry friction condition, experience has been for the different normal pressure, the different surface roughness, the different ultrasonic vibration amplitude, respectively. The results of experiment show the relation between kinetic coefficient of friction and surface roughness in the condition of ultrasonic vibration.Analysis results of experiment, conclusions have been done as following: kinetic coefficient of friction under ultrasonic vibration or no increase, with increasing of surface roughness Ra. kinetic coefficient of friction under ultrasonic vibration has decreased, is about from one-seventh to one-ninth of tradition kinetic coefficient of friction. Under the condition of different materials, variation rule of kinetic coefficient of friction with the surface roughness vary is the same. Normal pressure has no effect on kinetic coefficient of friction. As the ultrasonic vibration amplitude increase, kinetic coefficient of friction has decreased appreciably.