Theoretic And Experimental Investigation On The Aerostatic Porous Bearing

Aerostatic bearings have been applied widely on the ultra-precision machinery in the aviation, aerospace and the inertial measuring apparatus, because of its high rotational accuracy, calm operation, low friction and long life-span etc. Porous material can supply millions of micro-hole regarded as countless throttle, therefore porous aerostatic bearings have high load capacity and static stiffness. For the purpose of developing the porous aerostatic bearing that is the same with gas lubricant, on the base of theoretic analysis and material experiment, this paper has presented the mathematic model of carrying capacity, static stiffness and mass flow and theoretic formula of porous aerostatic bearing. A kind of porous bronze has been prepared. The following contributions have been made:The flowing characteristics of the different areas of the air lubricated porous bearing have been addressed ground on the Reynold Equation of viscidity compressed flow and of Darcy law of the flow transit through porous medium. The pressure distribution equation of the porous medium and the lubricate film are presented. It develops an important conclusion that the two equations are coupled.The fact that the vortex effects the dynamic stability mostly has been illustrated, the equation of continuity of flow lubrication is solve in porous aerostatic journal bearing under the dynamic stability condition with the linear iterative method, and the threshold mass considered as stability criterion is found. A new method to improve the dynamic stability of bearing by using double layer porous material with different penetrability is developed.The press distribution field of porous aerostatic bearing has been studied using both analytic and numerical method, compared with that of the former, it shows that the numerical method is much more effective and accurate, and FLUENT simulate is carried out to validate the conclusion.Powder metallurgy method is utilized to prepare a kind of porous bronze; a set of device to test the penetrability of the porous material is built. A technique that to find the penetrability through the experimental data by using the least squares method is presented,and farther the relationship between the porosity and penetrability is gained.The outcome of this dissertation has provided a stable basis of the application of the porous material in the field of gas lubrication. As well as the experimental investigation of porous bronze process an important reference to the development of other similar porous materials.