Measurement And Analysis Of Motion Errors Of Ultra-precision Hydrostatic Guideway

The manufacturing level of ultra-precision machine tools is an important criterion to judge the equipment manufacturing industry of a nation.The motion errors of hydrostatic guideways which are the main coupling parts of ultra-precision machine tools directly affects the machining accuracy.Therefore,the measurement and analysis of motion errors of hydrostatic guideways system have very important practical meanings.Firstly,aiming at the design requirements of hydrostatic guideways system,we have carried out the scheme design of structure system,control system and oil supply system.Based on the analysis and comparison of the guideways structure,the liquid static pressure guideway structure of the outer sliding frame is established,and the main parameters including the size and stiffness of the oil cushion structure are calculated.In order to achieve high accuracy of the guideway,a closed loop control system has been designed.Secondly,based on the analysis of the factors causing the motion errors of the guideway system,a motion error testing system based on plane flat crystal is established.The program of error evaluation algorithm is finished by MATLAB,and the man-machine interaction interface is designed based on GUI,which can quickly calculate the error value.Then,based on the CFD theory,the oil cushion oil film is simulated and analyzed by the Finite Element Method,and the variation trend of the oil film pressure is obtained by using the FLUENT.Kinematic models and Fourier series equations based on motion error factors are established.Based on the pressure law and model relation of the finite element simulation analysis,the influence law of the surface shape error amplitude on the motion precision of the guideways is studied through the grinding,and the accuracy of the Finite Element Analysis is verified.At the same time,the pitch and yaw errors of the guideways by the change of the supply pressure and the velocity of motion are studied by the contrast experiments.The higher motion speed is,the more obvious influence of the supply pressure on the motion errors is.Finally,in order to fulfill the high precision design requirements of the hydrostatic guideways system,based on the measurement of the positioning precision of the laser interferometer and the compensation method of the UMAC motion controller,which basically makes the positioning accuracy of the hydrostatic guideways meet the design requirements.The compensation result of the positioning accuracy of the whole system is tested through the turning experiment successfully.