Research On Macro-Mesoscopic Dynamic Characteristics Of Sliding Joint Surface

High-precision and high-performance as machine tools nowdays tend to be, the properties of the machine tool joint surface are playing more and more important roles to effect the whole mechincal dynamic properties. It’s of significant meaning in both theoretical field and engineering application to research the mesoscopic mechanical properties of mechanical joint surface and the relationship between its macroscopic dynamic properties and mesoscopic mechanical properties since the joint surface stiffness is the weakest part in the stiffness of whole mechanical structure as well as the mesoscopic dynamic characteristics of mechanical joint surface is one of the key technology and basic research theory of the dynamic design of complex mechanical systems, micro-mechanical systems and design optimization. It’s an important science and technology issue in the development of the domestic machine tool industry has with a very broad application prospects.Based on contact mechanics, modal analysis, fractal theory, fluid mechanics, and the average flow of the generalized Reynolds equation, etc., analysis and research of dynamic properties in both macroscopic and mesoscopic aspects are studied combining with lubricants exudation mechanism between the joint surface and extrusion properties of the oil film.Mathmatical models of integrated equivalent stiffness and equivalent damping under partial lubrication condition is derived with summaring W-M fractal function, fractal theory, fluid properties and the average flow of the generalized Reynolds equation. The results indicate that an ideal state for the contact stiffness and damping of joint surface is reached when the actual contact area ratio of joint surface turns to a certain value. An important guidance is provided from this research to the rough surface manufacting and initial normal load application. Based on prior studies, adopting engineering equivalence principle, a slide rail experimental platform is designed and established with equivalent single degree of freedom system universal joint surface unit area parameter identification method. Meanwihle, experimental identification of stiffness and damping in both static and dynamic states are proceeded. A good condition of the stiffness and the damping of the joint surface under an appropiate normal load is achieved in the end which agrees well with the mesoscopic dynamic properites of joint surface simulation results.In this paper, starting with practical application, mesoscopic mechanical properties of joint surface under partial lubrication condition is modeled and the dynamic characteristics parameters of the sliding surface are acquired. A good reference of connection of macroscopic and mesoscopic dynamic characteristics of joint surface is offered.