Performance Investigation Of Aerostatic Thrusting Gas Bearing With Discontinuous Slot-restricted In Small Gap

Aerostatic gas bearings are widely used in precision and ultra precision machining. In order to improve the bearing capacity and stiffness of gas bearing, the pressure distribution in the gas film should be improved. By reducing the gas film gap to achieve the above objectives, the method is limited by the processing precision, and has not been further studied in the application of precision spindle.At present, with the development of precision machining technology, new processing methods and methods are constantly emerging, the precision machining ability will continue to improve. In addition, the micro engine has attracted great attention and research of the international academic and scientific community in the last ten years. In micro engine structure, the diameter of the micro rotor is generally less than 10 mm, and the structure size and working clearance of the supporting gas bearing will be greatly reduced. Therefore, it is very necessary and feasible to carry out the research of the static pressure gas bearing in the micro gap.In this paper, the characteristics of the thrust bearing with the slot-restricted with small clearance are studied, and the FLUENT software is used to simulate the flow field. Firstly, the three-dimensional model is established, when the gas film thickness in 5～15 μm, according to Knudsn number (kn=λ/h), it may be in the slip flow, we analyze the flow field of the gas bearing with discontinuous slot-restricted on the small clearance with the slip boundary conditions, the results show that when the film thickness≤4μm, we can neglect the impact of the boundary slip, and analyze the influence of the surface roughness, and then calculate the slit structure, including:continuous or discontinuous, circumferential, axial or circumferential, slit width, slit depth, revealing the effect mechanism and the law of the structure of the small clearance.Secondly, we analyze the slit throttling thrust bearing model, simplified the flow between two parallel plates, derived the pressure and the flow distribution formula, and compared with the numerical calculation. The results show that both of them are consistent, and the effect of slit structure on bearing characteristics is analyzed theoretically.Finally, the experimental test of the bearing capacity of the thrust bearing with the slot-restricted with small clearance is carried out, which verifies the correctness of the FLUENT numerical calculation. The calculation results of this paper have a certain guiding role for the design of static pressure gas bearing.