Dynamic Modeling Of Hydrostatic Bearing Joint And Design Of The Experimental System

Nowadays,hydrostatic bearing is widely used in various kinds of machine tools,especially high-precision heavy-duty machine tools.As the core part of machine tool,the performance of static pressure support directly affects the quality of machine tool processing.The performance of hydrostatic bearing can be divided into static and dynamic characteristics,improving the stability and dynamic characteristics of the hydrostatic bearing is the major topic of discussion.Therefore,in order to meet the requirements of high efficiency and high precision in machine tool production,and improve the capacity of machine tools and ensure the stability of the machine tool,it is necessary to study the dynamic performance of hydrostatic support.In this thesis,the oil film is used as the joint of hydrostatic bearing and the dynamic characteristics of hydrostatic bearing joint are studied.First,get the Taylor expansion of the expression of the oil film force formula of hydrostatic bearing on the basis of the traditional hydrostatic bearing dynamics model,and the expression of oil film with high stiffness and high damping is obtained.Substitute the new expression into the hydrostatic bearing motion equation to obtain the nonlinear dynamic model of hydrostatic bearing joint.Then,the identification method of dynamic parameters of hydrostatic bearing joint is proposed based on least square method.Second,according to the design requirements of the machine tool and the design method of the hydrostatic guideway,the size structure of the guide rail for the experiment is determined.The experimental system is based on the hydrostatic round guide which is supplied by fixed displacement pump.A test scheme is proposed to study the influence of different initial loading force and fuel flow rate on the dynamic characteristics of hydrostatic bearing.Last,we obtained the best fitting formula of the test displacement by processing the experimental data,and determined the optimal number of hydrostatic bearing dynamic model by comparing the experiment under different working conditions and the identification of dynamic stiffness and damping parameters.The influence of different step load and common flow on the three degree of stiffness and damping coefficient before hydrostatic bearing is analyzed.