| The aerostatic bearing is a non-contact gas film lubricated bearing.After the external high-pressure gas is throttled by the restrictor,the pressure gas film is formed in the gap between the bearing and the supported parts,which makes the hydrostatic bearing have bearing capacity.This type of bearing has the advantages of small friction heating,high working accuracy and long service life.It realizes the accuracy of the moving mechanism to be improved from the micron level to the nanometer level.It is widely used in the fields of precision and ultra precision processing equipment,aerospace equipment,high precision measuring equipment,etc.However,the bearing has the weakness of small bearing capacity and low stiffness.In order to improve the bearing performance,the aerostatic bearing unit combing orifice throttling and surface throttling is taken as the research object in this paper.designs Composite throttle aerostatic bearing units with different throttle groove shapes are designed and subjected to static and dynamic characteristics simulation analysis and experimental research to provide a reference for the design of aerostatic bearing.In this paper,the finite difference method is used to decompose the static model,and the discrete form of the static model is obtained.After the boundary conditions are given,a MATLAB program is written to simulate the pressure distribution in the air film of the aerostatic bearing unit.According to the pressure calculation results,the static characteristics can be calculated.Using MATLAB simulation,the static characteristics of the aerostatic bearing unit under the condition of small orifice throttling and composite throttling with different throttling slot shapes are obtained,and the influence law of its static characteristics is analyzed.Two kinds of bionic throttling slots are designed.The program calculating anti tilt torque and angle stiffness is written in MATLAB.The static characteristics and anti tilt ability of the aerostatic bearing unit under the former two kinds of throttling slot shapes are compared,and the selection methods of different throttling slot shapes are analyzed.The dynamic control equation of aerostatic bearing unit is obtained by perturbation method.On the basis of the calculation results of static pressure distribution,the matlab program for calculating dynamic characteristics is compiled by finite difference method and over relaxation iteration method.The dynamic pressure distribution is simulated by MATLAB.The curves of dynamic stiffness and damping coefficient under different film thickness are obtained.The influence of film thickness on the dynamic characteristics of aerostatic bearing unit is analyzed.The static characteristics of orifice throttling and composite throttling aerostatic bearing unit are measured by the experimental platform,and the experimental results are compared with the simulation results to verify the reliability of the static characteristics solution method.Through the micro vibration measurement experiment,the influence of gas source pressure and gas film thickness on the micro vibration of composite throttling bearing unit is studied. |
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