Design And Analysis Of Static & Dynamic Performance Of The Aerostatic Spindle Of Ultra-precision Machine Tool

Mechanical cutting techniques for the microstructure and micro-components, due to their high efficiency, low cost and capability of processing a wide range of materials, have drawn increasing attention. Ultra-precision machine tools for microstructure and micro-components require the spindle rotating parts of high precision. Aerostatic spindle, which is characterized of high accuracy, high speed and low friction, has been widely applied in the field of ultra-precision machine tools. The stiffness and load capacity of aerostatic spindle is low, while the high speed aerostatic spindle is of poor stability. All these drawbacks limit the spread of the applications of aerostatic spindle, which have a close relation with the compressible gas lubricant. So it is of great importance to explore the static and dynamic characteristics of aerostatic spindle deeply.1. The aerostatic spindle unit for ultra-precision machine tool is designed. The structure style, the gap thickness of the air bearing, the style of gas throttle, the orifice parameters and the supply gas pressure are identified. The bearing capacity, static stiffness and gas consumption are also calculated by an engineering method.2. The numerical solution of the Reynolds equation is completed. The nonlinear Reynolds equation is solved by a series of discrete linear equations, which is got by finite difference method, using relaxation iteration method.3. The pressure distribution is got in the gas film. After that, the load capacity is calculated by Simpson integration. Also, the stiffness is given by finite difference method.4. The dynamic stability analysis of the shaft-bearing system is given. Based on the damping performance analysis, the influence factors on the whirl instability are studied. The modal properties of the aerostatic shaft-bearing system are calculated and analyzed by finite element method, with the gas film compared to soft springs. At last, the whirl critical speed is given, with the consideration of whirl instability conditions.