Research On Motion Linearity Model And Regulation Technology Of Closed Hydrostatic Guide

The rapid development of modern science and technology requires higher and higher accuracy of parts processing,and various industries have very urgent requirements for precision and ultra-precision machine tools.The guide rail is one of the important functional parts of the machine tool,which directly affects the machining level of the machine tool.The hydrostatic guides has the advantages of low friction coefficient,high support rigidity,large bearing capacity etc.It is undoubtedly the best choice for precision machine tool guides.This paper takes Ultra-precision milling machine tools as the research background,and uses liquid hydrostatic guides as the research object.According to the requirements of ultra-precision machining for the high precision and high stability of hydrostatic guides,four pairs of oil pads are carried out.Research on three aspects of precision model,performance simu lation and precision regulation of hydrostatic guides.(1)The slider moves between the guide surfaces of the guide rail and is the moving part of the static pressure guide rail.During the movement of the slider,due to the contour error of the guide surface of the guide rail,the thickness of the oil film between the slider and the guide rail will continuously change,which will cause the bearing capacity of the guide rail to change accordingly,which will affect the balance of the slider.In order to maintain a balanced state,it is necessary to deviate from the ideal motion trajectory,which will cause linear deviation and angular deviation.This paper first analyzes the change law of the bearing capacity when the slider moves in the area of a single oil cushion and establishes a balance equation and an precision model.Based on this,an precision model of the four opposing oil cushion static pressure guides is established,and the static analysis is used to establish The balance equation is solved to obtain the model of the relationship between the contour error of the hydrostatic guides rail and the motion accuracy.According to this model,the error averaging effect of the oil film is studied,and the influence of contour error and related structural parameters on the error averaging effect and straightness error are mainly analyzed.(2)The slider always moves along the guide surface of the guide rail,and the oil film pressure will cause deformation of the entire guide rail,and then affect the overall contour of the guide surface where the guide rail contacts the slider.A simulation study of the deformation of the guide rail pressure plate during the movement of the slider in different positions on the four-positioned oil pad static pressure guide rail is performed,and the deformation rule is analyzed.Firstly,the oil film pressure distribution is analyzed by simulating the static oil film fluid,and then the equivalent oil film pressure is determined according to the oil film distribution.Then,the simulation study is performed on the slide plate at different positions,and the equivalent oil film pressure causes deformation of the guide rail pressure plate.(3)The motion accuracy of the hydrostatic guides is directly related to the machining accuracy of the machine tool.Analyze the working principle of the closed hydrostatic pressure rail test bench.Laser interferometer was used to measure the motion straightness of the hydrostatic guides rail,including the horizontal straightness and vertical straightness of the guide rail,and the test data was processed,calculated and analyzed.Aiming at the situation that the profile of the guide rail changes due to the deformation of the pressure plate,a vertical straightness control scheme for the static pressure guide rail is proposed.The principle of reverse compensation is used to design the vertical straightness control experiment.Principle,test device model,piezoelectric crystal’s working force and position relationship with stroke,and calibration of piezoelectric crystal parameters.The finite element simulation is used to determine the power value of the piezoelectric crystal that should be preset at different strokes.The calibration test is designed according to the characteristics of the piezoelectric crystal to calibrate the voltage correlation coefficient and displacement correlation coefficient...