Study On Characteristics Of Gas Hydrostatic Thrust Bearing With Micro-Orifice Restrictor

High-speed precision machine tool is the main tool for processing mechanical products,its performance determines directly the quality of mechanical products,and the core component of precision machine tool is the motorized spindle.With the development and perfection of the theory of gas lubrication,the bearing capacity and stiffness of aerostatic bearing are improved,which can meet the needs of precision machining.Therefore,it becomes the main support modes of the spindles of the precision machining equipment and testing equipment.Combining the advantages and disadvantages of the existing slot restrictor and orifice restrictor,this paper put forward a new kind of micro-orifice restrictor,which belongs to the category of orifice restrictor,but it breaks through the traditional structure of orifice restrictor.There is no air cavity at the outlet of orifice,and all of them are through holes.At the same time,combining the restrictor characteristics of slot restrictor,and on the basis of bearing stiffness,increase the number of air supply holes,improve the pressure distribution and the characteristics of bearings.According to the physical model of orifice restrictor and annular restrictor,the physical model of micro-orifice restrictor is established.Based on Reynolds equation,N-S equation,equation of motion,equation of state,and equation of continuity in gas bearing theory,the mathematical equation for solving the dynamic and static characteristics of gas hydrostatic thrust bearing with micro-orifice restrictor is derived.The static equation of gas hydrostatic thrust bearing with micro-orifice restrictor is calculated by finite difference method,and solved by Matlab programming.According to the physical model of micro-orifice restrictor gas hydrostatic thrust bearing,the simulation model of micro-orifice restrictor gas hydrostatic thrust bearing is established and meshed by using SolidWorks software,Gambit software and ICEM CFD software,and the model is solved by using Fluent software.The effects of gas supply pressure,film thickness,number of gas supply holes,dimensionless distribution radius of gas supply holes and diameter of gas supply holes on the dynamic and static characteristics of bearings are studied by using the above two methods.The static characteristics of gas hydrostatic thrust bearing with micro-orifice restrictor are compared with gas hydrostatic thrust bearings with slot restrictor,orifice restrictor and annular restrictor under the same working and structural parameters.Finally,aerostatic thrust bearing with micro-orifice restrictor is optimized by using the orthogonal test method and grey theory.According to the results of simulation and optimization,aerostatic thrust bearings with micro-hole restrictor are designed,processed and manufactured.The key structures of the processed bearings are measured by precision measuring instruments.An experimental platform for the dynamic and static characteristics of gas bearings is designed and built.The modal,static bearing capacity,static stiffness and stability of the bearings are analyzed experimentally on the experimental platform.The dynamic and static characteristics of gas hydrostatic thrust bearing with micro-orifice restrictor are simulated and experimentally studied,which provides theoretical and experimental basis for the research of gas hydrostatic thrust bearing.