高速静压气体轴承转子系统的稳定性分析

发布时间：2018-02-12 12:17

本文关键词： 气体轴承动态刚度系数动态阻尼系数稳定性轴承转子系统　出处：《哈尔滨工业大学》2012年硕士论文　论文类型：学位论文

【摘要】：气体轴承显现出了很多传统轴承所没有的优点，如不需要润滑系统、工作时无摩擦损耗、振动小、工作寿命长、维护费用低等。因此，气体轴承已成功应用于离心分离机、磨床、真空泵等设备，以提高工作转速，降低能量损耗，提高位置精度。然而，高速气体轴承也有其不足之处，如承载能力较低，同时由于润滑介质是空气，稳定性成为高速气体轴承的主要问题。当用气体轴承支承的转子达到足够高的转速时，将会出现转子失稳现象，这种失稳的出现是由于气膜不再具有阻尼作用而导致，由此产生了自激振动，这种自激振动阻碍了气浮轴承的广泛运用。为了解决以上问题，本文采取在机体与轴承之间嵌入O型橡胶圈的方法，使轴承柔性安装，来提高系统稳定性。因此，本文主要研究的是高速静压气体轴承转子系统的动态稳定性。首先，采用线性摄动法，在动静压混合气体轴承雷诺方程的基础上，对相关变量作一阶泰勒展开，推导出气体轴承动态刚度与动态阻尼系数的计算公式，然后在数值计算中对线性偏微分方程组的求解采用中心差分法，逐次超松弛迭代法，数值积分采用Simpson复化积分法，同时分析偏心率、转子自转转速、涡动比、供气压力等对动态特性系数的影响。然后建立轴承转子系统模型，带入前面所求得的动态特性系数，建立系统的动力学方程；同时采用Routh-Hurwitz稳定性判别法，判断系统稳定性；并分析引入O型橡胶圈，对系统稳定性的影响；分析供气压力、偏心率、涡动比等对系统稳定性的影响；同时采用New-mark逐步积分法，求解系统不平衡响应。最后是关于气体轴承转子系统实验台的建立，实验以及对实验结果的分析，试验台包括：夹持机构，电主轴，测试装置；实验包括：升速测试，测得转子的临界转速，以及不同转速下转子的不平衡响应幅值。由于转子不平衡或外部激励等原因导致的轴承转子系统的剧烈振动，，这种振动严重影响了系统的工作性能且缩短了整个系统的使用寿命，因此有必要设计合适的轴承，使轴承转子系统具有合理的刚度特性与阻尼特性，以此削弱这种振动。
[Abstract]:Gas bearings show many advantages that traditional bearings do not have, such as no lubrication system, no friction loss, small vibration, long working life, low maintenance cost, etc. Therefore, gas bearings have been successfully used in centrifugal separators. Grinding machines, vacuum pumps and other equipment to increase the speed of work, reduce energy loss, improve the accuracy of the position. However, high-speed gas bearings also have their shortcomings, such as low bearing capacity, and because the lubricating medium is air, Stability becomes the main problem of high speed gas bearing. When the rotor supported by gas bearing reaches a sufficiently high speed, there will be instability of the rotor, which is caused by the fact that the film no longer has damping effect. As a result, self-excited vibration, which hinders the wide application of air-bearing. In order to solve the above problems, this paper adopts the method of inserting O-type rubber ring between the body and the bearing, so that the bearing can be installed flexibly to improve the stability of the system. In this paper, the dynamic stability of high-speed hydrostatic bearing rotor system is studied. Firstly, the linear perturbation method is used to calculate the dynamic stiffness and damping coefficient of the gas bearing, based on the Reynolds equation of the static and static pressure mixed gas bearing, and the first order Taylor expansion of the related variables is made. Then, the central difference method, successive overrelaxation iterative method and Simpson complex integral method are used to solve the linear partial differential equations. The eccentricity, rotor rotation speed and vorticity ratio are analyzed at the same time. The influence of gas supply pressure on dynamic characteristic coefficient. Then establish the bearing rotor system model, bring into the dynamic characteristic coefficient obtained in the front, establish the dynamic equation of the system; at the same time, use the Routh-Hurwitz stability discrimination method to judge the stability of the system, and analyze the introduction of O-type rubber ring, The influence of air supply pressure, eccentricity and vortex ratio on the stability of the system is analyzed. At the same time, the unbalance response of the system is solved by New-mark step by step integration method. Finally, it is about the establishment, the experiment and the analysis of the experimental results of the gas bearing rotor system. The test bench includes the clamping mechanism, the motorized spindle and the testing device, and the experiment includes: the test of raising speed, the measurement of the critical speed of the rotor, the measurement of the critical speed of the rotor, And the unbalance response amplitude of rotor at different speed. Because of the violent vibration of the bearing rotor system caused by the rotor imbalance or external excitation, this vibration seriously affects the working performance of the system and shortens the service life of the whole system, so it is necessary to design a suitable bearing. In order to weaken the vibration, the bearing rotor system has reasonable stiffness and damping characteristics.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TH133.36

【参考文献】