Analysis Of The Dynamic And Static Performance Of The High-speed Aerostatic Spindle

High-speed precision aerostatic spindle is the core part of ultra-high precision machine tool. It is widely applied in the processing of minimal components and high precision surfaces for its advantage of high-speed, high precision, no temperature rising and wearing. While some limits such as limited bearing capacity and bad performance against unbalanced status exist on the spindle, which put forward great requirement on its design and manufacture. Hence, aimed at the research of high-speed precision aerostatic spindle, this article explores to conduct the systematic research on the dynamic and static performance of the spindle, combined with principles, simulation and applying experiment, with the detailed work as follows:(1) The performance of key structures of the spindle—aerostatic bearing was calculated applying CFD simulation software Fluent. Features of flow fields of the bearing were analyzed through changing a train of structure parameters and working parameters, and influences of bearing capacity and gas consumption on those parameters of radial bearing and thrust bearing were gained. The best structure parameters were selected based on the principles of increasing bearing capacity under the condition of decreasing the gas consumption, which provide important reference on the design and optimization of aerostatic bearing.(2) Principles and methods of the dynamic balancing of the rotor of the spindle were illustrated, and dynamic balancing emendation formulas of the rotor were established based on the influence coefficient method, through which the influence errors between two emendation plates were distinguished, and dynamic balancing emendation experiments were carried out choosing proper emendation plates. Finally the remaining unbalanced amount was decreased meeting the allowable requirement, which solved the problem of the dynamic balancing of this small high-speed rotor.(3) The dynamic and static performances of the rotor of the spindle were analyzed applying finite element analysis software WORKBENCH, and the distribution of stress and strain when the rotor is under static loading, the free modal, the modal under work condition and the critical speed were gained. Then the rules of influences on several parts of the rotor under different kinds of exciting forces were gained through harmonic response analysis. These studies show that the natural frequency of the rotor under work condition is lower than that under free condition and the first-order vibration would decrease the stiffness of the spindle.(4) Comprehensive experiments were carried out to test the speed, jumping error, stiffness and grinding processing performances of the spindle applying measuring equipments and processing equipments, through which the results of simulation and dynamic balancing emendation were verified, the rules of speed and jumping error of the spindle were gained, and performances of the spindle before and after dynamic balancing emendation of the rotor were compared. These studies show that increasing the dynamic balancing precision will decrease jumping error of the spindle and increase the processing precision.