Research On The Structure Design And Sealing Method Of Aerostatic Bearing Working In Vacuum Condition

With the rapid development of high-tech,the working condition,the speed and accuracy of the bearing requests are constantly mproving.The aerostatic bearing is applied to the ultra precision equipment such as coordinate measuring machine,micro electronics manufacturing platform due to its fast speed,high accuracy,low viscous friction and low power consumption advantages.With the constant development of next-generation lithography,interferometry,semiconductor detection technology,the bearing working condition changes into vacuum or approximately vacuum condition gradually.Comparing to the atmosphere environment,the inter gas flow field of the aerostatic bearing working in vacuum condition is more complex,so the bearing's dynamic and static property will both get changed,and we must add the sealing structure to reduce the gas leakage.At present,the research on the aerostatic bearing working in vacuum condition is not rich,and the method of bearing structure design and parameter optimization is not mature.So this paper designs the aerostatic bearing working in vacuum condition,uses the finite element method and the modified lubrication model to simulate the gas flow field of aerostatic bearing working in vacuum condition,analyzes the influence of structural parameters and operating parameters on the performance of the bearing,and do the corresponding simulation and experimental research mainly including the following:1.In order to research vacuum condition's influence on the properties of aerostatic bearing,the aerostatic bearing is designed working in vacuum condition,multilevel exhaust slot seal structure are adopted to decrease the amount of bearing gas leak in the vacuum condition.The gas leakage can be effectively reduced by increasing the exhaust and decreasing the exhaust slot radius slot radius with the analysis of the the steady property and the gas leakage of the aerostatic bearing in vacuum condition.2.The performance parameters of gas thickness,gas pressure distribution,bearing capacity and gas consumption in aerostatic bearing steady state is obtained by finite element method numerical analysis.The influence of the structural parameter and the working parameter on aerostatic bearing properties working in low vacuum condition is analyzed,and the results show that the orifice diameter can improve the capacity and stiffness of bearing,and the best gas film thickness will increase.Gas pressure will increase the the capacity and stiffness of bearing,but in order to maintain the stability of bearing,the gas pressure should not be too big.The capacity of the bearing will increase and the gas consumption will increase when working in vacuum condition.3.The applicable scope of the different modified lubrication model is analyzed to achieve the accurate gas film pressure distribution of the steady aerostatic bearing working in vacuum condition.The influence of the working parameter on aerostatic bearing properties working in high vacuum condition is analyzed,and the results show that the gas film pressure distribution of the bearing load area will be quickly achieve by one order lubrication modle,and the gas film pressure distribution of the bearing sealing area will be achieve more accurate by 1.5 order lubrication modle.The results of the numerical simulation is obtain by combining with the different models,and the results show that the seal area have little effect on the properties of the bearing and it can be neglected with out considering the gas leakage.The influence of the structural parameter and the working parameter on the bearing porperties are consistent with the results achieved by finite element method,it verifies the feasibility of numerical simulation method with each other.4.The vacuum chamber and the detection equipment of aerostatic bearing are designed working in vacuum condition.The experimental datas of the thickness,gas pressure in vacuum and exhaust slot are collected by the sensor,and it is compared with the simulation and literature data to prove the peasibility of the design.By the research,it is expected to acquire the numerical simulation method of aerostatic bearing working in vacuum condition and acquire the influence of the structural parameter and the working parameters on aerostatic bearing.Such works can provide the reference frame and technology support for optimization design and performance analysis of aerostatic bearing in the future.