| High speed spindle is an important part of precision grinding,with the continuous development and progress of ultra precision manufacturing industry,its application changed more and more,and it has higher requirements for precision and speed.The performance of the air bearing spindle is superior,with the lubricating of the air,the spindle rotor does not directly contact with the bearing,and it can easily reach high speed without generating too much heat.But at present,the main application of the air bearing spindle are small orifice throttling bearings,and the capacity of the bearing are small.Therefore,in order to improve the bearing capacity,this paper studies the multi orifice throttling bearing.In this paper,the software named FLUET is used to analyze the static performance of porous aerostatic bearing,researching the influence of bearing permeability,length diameter ratio and gas supply pressure on its static stability.The dynamic and static characteristics of spindle rotor are analyzed by using the finite element software ANSYS,the details are as follows:The rotation speed,stiffness and rotation accuracy of the air bearing spindle with orifice throttle bearing are tested by using optical fiber rangefinder.The shortcomings of the spindle are analyzed,and the variation law of the spindle rotation speed with the air supply pressure is obtained.The movement law of gas in porous material is expounded,the movement equation of gas in porous material and gas film gap is solved,the theoretical model is established,and the influence law of permeability,gas supply pressure,eccentricity and other parameters on bearing bearing capacity is obtained;the integral impeller is used to drive,the turbine size should be calculated,and the gas path of power part is designed;the main bearing capacity is calculated.The intake and exhaust passages of the shaft are designed.The software FLUENT is used to simulate the air flow field of porous bearing.The influence of porous material permeability,air supply pressure,eccentricity,air film thickness and other parameters on the bearing capacity of radial bearing are analyzed.The influence of porous material thickness and air film thickness on the bearing capacity of thrust bearing are also analyzed.The air flow field of orifice throttling radial bearing is simulated and analyzed,and the bearing capacity is calculated compared with the porous bearing.The static analysis,modal analysis and harmonic response analysis of the rotor are carried out by using the workbench module of ANSYS software to obtain the resonance frequency of the main shaft under different conditions,and then,the critical speed of the main shaft is calculated to obtain the stable operation speed range.The simulation results show that,under the condition of similar coverage area,the bearing capacity of porous radial bearing is larger than that of the orifice throttling radial bearing,and the static and dynamic stability of the spindle rotor under this load can be guaranteed. |
