| Summary: | 碩士 === 國立中正大學 === 機械系 === 89 === The purpose of this work is to analyze the static characteristics of a composed air bearing designed for the high speed spindle. The composed air bearing consists of orifice-type restrictors based on the aerostatic design principle and herringbone grooves based on the aerodynamic design principle. The static characteristic of the composed air bearing means that the transient characteristics of pressure distribution and the dynamic variation of the bearing gap are ignored.
A mathematic model including Renorld equation and the boundary conditions of the composed air bearing has been established. A finite difference method using the Alternating-Direction-Implicit method is then applied to obtain the discrete form of the mathematic model. The numerical analysis of the discrete model of the composed air bearing is based on the Alternating-Direction-Implicit method associated with the Successive-Over-Relaxations.
In this work, the characteristic of the pressure distribution, load capacity, stiffness and attitude angle of the composed air bearing under different spindle speed have been studied. Both the aerostatic and aerodynamic effects can be calculated based on the established model and numerical method. Parameters of the herringbone grooves such as the angle, length, and depth of the grooves were analyzed. Performance comparisons between the aerostatic bearing and composed air bearings were also studied.
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