Research On The Correlation Mechanism Between Error Of Oil Film Interface Of Hydrostatic Guide And The Geometric Error Of The Machine Tool

With the advancement of research and development of weapon systems in my country's major scientific projects and defense fields,diamond turning is widely used in the processing of high-performance parts such as precision physical experimental samples and optical parts.Hydrostatic guides have become the main core components of ultraprecision lathes due to their high precision and high rigidity.The structure of optical parts is gradually complicated and miniaturized,which makes the load conditions of hydrostatic guide rails more complicated,and puts forward higher requirements for the design of key structural parameters,bearing characteristics and geometric accuracy of the guide rails.However,the surface shape error of the hydrostatic guideway parts degrades its geometric accuracy,which is ultimately manifested as the change of the geometric error of the machine tool.Therefore,starting from the optimization of the static characteristic parameters of the hydrostatic guideway,the influence mechanism of the oil film bonding surface error on the geometrical accuracy of the guideway is analyzed,and the geometrical error of the guideway is used as an intermediate variable to explore the correlation mechanism between the surface error of the guideway part and the geometric error of the machine tool.The main research contents and conclusions are as follows:(1)Static characteristics analysis of hydrostatic guide rail based on fluid-structure coupling.Based on the hydrostatic bearing theory,the relationship between the performance parameters of the guide rail and the flow field structure parameters is studied,and the correlation analysis of the flow characteristics and flow field structure parameters of the fluid domain is carried out with the help of CFD simulation software,and the optimal parameter combination of the flow field structure is determined.Based on the fluid domain simulation results,the fluid-structure coupling analysis model of the guide rail system is constructed.The static characteristics of the guide rail show that the main factors causing the elastic deformation of the structure are oil pressure and bolt preload,and the elastic deformation of the guide rail pressure plate is different at different strokes.The deformation error of the oil film joint surface will cause the change of the oil film gap,and the stiffness and geometric accuracy of the guide rail system will change accordingly.(2)Research on the influence of the oil film bonding surface error of the hydrostatic guide rail on its geometric error.Based on the fluid-solid coupling model,the elastic deformation law of the guide rail structure under the action of oil pressure and other factors is discussed,and the error mathematical model to characterize the joint surface under the action of manufacturing,assembly and oil pressure is proposed.A deformation error transfer model considering oil film homogenization is constructed,and the action mechanism of the oil film joint surface error of the guide rail on the geometric error of the guide rail is studied.Periodic manufacturing error and deformation error of guide rail and slider all degrade the geometric accuracy of guide rail.Under the effect of oil film homogenization,the influence of joint surface error on the geometric error of guide rail shows a decreasing trend,and it tends to decrease with the reduction of guide rail error.smooth.The error amplitude of the joint surface is the main factor affecting the linearity error of the guide rail,and the angle error is sensitive to the wavelength and phase difference of the error function.(3)Correlation analysis between the oil film bonding surface error and the geometric error of ultra-precision machine tools.The geometric error analysis model of diamond lathe is established based on multi-body system theory.The analysis of the error sensitivity coefficient of the machine tool shows that the positioning error and straightness error of the hydrostatic guideway are the key factors causing the geometric error of the machine tool,and the sensitivity to the angle error of the guideway is low.Taking cylinder end face machining as an example,the straightness error and pitch angle error related to the feed position of the guide rail are substituted into the geometric error model of the machine tool,and the variation law of the end face shape error under different error amplitudes of the oil film joint surface is obtained.The correlation between the geometric error of the ultra-precision diamond lathe and the error of the oil film interface is clarified.