Radial rotation error prediction method for static air pressure main shaft

Abstract

Provided is a radial rotation error prediction method for a static air pressure main shaft. The method conducts prediction in consideration of micro-scale effects of air film flow in a static air pressure bearing and nonlinear dynamic characteristics. According to the structure and a principle of the static air pressure bearing, flow factors embodying the micro-scale effects are introduced to establish a mathematical model of the air film flow of the static air pressure radial bearing under micro-scale; an air film is transformed into a spring damping system with two freedom degrees perpendicular to each other, the flow model is calculated, and nonlinear dynamic stiffness and damping coefficients are assigned to the spring damping system under the micro-scale; according to the structure and working principle of the static air pressure main shaft, a bearing-rotor system model composed of the air film and a rotor is established; based on the characteristics of main shaft vibration, a mathematical model of dynamic vibration of the bearing-rotor system is established; various vibration errors of the static air pressure main shaft are obtained, and total radial rotation errors of the main shaft are obtained by integrating the various errors.

Description

technical field The invention relates to a rotation error prediction method, which is suitable for the prediction and analysis of the rotation error of an air static pressure spindle under different working conditions, and can realize the time domain and frequency domain signal prediction of the vibration signal of the air static pressure spindle. Background technique Aerostatic spindle is an important processing equipment in the process of precision and ultra-precision machining, and its motion error directly affects the surface quality, shape accuracy and roughness of the processed parts. Therefore, it is very important to predict and analyze the rotation error of the aerostatic spindle, which is of great significance to the optimal design and error monitoring and control of the aerostatic spindle. During the actual operation, the aerostatic spindle will produce forced vibration, self-excited vibration and yaw vibration due to the action of external force, self-gravity an...

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Problems solved by technology

Due to the compressibility of the air film in the aerostatic bearing, the fluctuation of the air film will be directly reflected in the vibration of the spindle; at the same time, because the bearing gap of the aerostatic bearing is at the micron level, the gas flow inside it belongs to the micro-scale flow. It will show micro-scale effects that traditional flow does not have, such as: rarefaction effect, speed slip, etc. These micro-scale effects will affect the dynamic characteristics of the bearing, thereby affecting the vibration of the main shaft

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