Simulation Study On Mechanical Properties And Straightness Of Hydrostatic Guideway

With the high-end equipment in the processing of optical parts and some large-scale complex parts,the demand for processing accuracy is higher and higher,and the position of ultra precision machine tool is higher and higher in the machine tool industry.Ultra precision machine tools have very high requirements for key moving parts,which generally require that the accuracy of repeated positioning,movement straightness,spindle runout,spindle rotation,etc.reach the nanometer level,or even higher.Guide rail is a good part of linear motion of machine tool,but the accuracy of ordinary guide rail can not meet the requirements of ultra precision machine tool.Because of its high precision,high stability,low vibration and low friction,hydrostatic guideway has become the most suitable linear moving part of ultra precision machine tools,so it is widely used in ultra precision machine tools,and scholars at home and abroad have done extensive research on it,including bearing capacity characteristics,stiffness,throttle hole,oil cavity structure,etc.,but the research on the straightness of slider motion is not deep enough or few Not really.The existing researches on the straightness of sliding block are to first give a feature plane(generally,the given plane is described by trigonometric function),make the sliding block move on it,and then change the phase,amplitude or wavelength of trigonometric function to explore the movement of sliding block on these planes.In fact,the surface of guide rail is irregular and uneven,which is compared with the existing researches It is assumed that there is a large difference between the rail surfaces.Therefore,in order to fit the actual situation better,this paper has done the following research:(1)A hydrostatic guideway table is designed.ANSYS simulation analysis is used for some structures such as oil cavity,small hole and plate,and the selection is made according to the actual situation.Then the overall structure of the platform is optimized by simulation,which greatly reduces the deformation and improves the rigidity of the table.(2)The static characteristics of the designed platform are analyzed.The influence of the bearing capacity of the oil cavity and the diameter of the restrictor on the bearing capacity,flow rate and throttling ratio is analyzed by using ANSYS software.The pressure distribution and bearing capacity change in the oil cavity at different speeds are simulated and analyzed.It is found that the bearing capacity of the oil film increases with the increase of the relative displacement of the oil film,and the larger the hole diameter is,The larger the bearing capacity is,the larger the flow rate is,and the smaller the throttling ratio is;the increase of the speed will cause the pressure of the oil cavity to be stratified along the speed direction,and the larger the speed is,the more stratified the bearing capacity will not change much;through the fluid structure coupling simulation analysis,it is found that in the sliding block movement,the guide rail base is not deformed,the maximum deformation is located at the screw,and the maximum deformation is 0.09 mm.(3)This paper deduces the calculation function of the straightness from the guide rail surface to the sliding block,and then analyzes the influence of the number and arrangement of screws,the pre tightening force of screws,the flatness of guide rail and the oil supply pressure on the straightness of the sliding block by using the ANSYS software,and summarizes the corresponding laws,and analyzes the influence of the sliding block on the guide rail when it moves to different positions by simulation The more the number,the smaller the deformation of the sampling line,the smaller the straightness of the slide;the smaller the screw preload,the smaller the deformation of the sampling line,the smaller the straightness of the slide;the higher the flatness requirement of the guide rail,the smaller the straightness of the slide;with the increase of the oil supply pressure,the straightness of the motion first increases and then decreases,but the change amplitude is very small.(4)The experimental platform is set up and the simulation results are verified by experiments.Through the comparison,it is found that the experimental results are the same as the theoretical simulation results,and there is a small gap in the numerical value,so the simulation results are basically correct.