空气轴承提高气浮系统稳定性的阻尼技术

Improving Damping Capacity of the Aerostatic Bearing

静压空气轴承拥有清洁、近零摩擦等优点,是一种优秀的运动导向承载部件,但是它在承载方向上阻尼较小,对外界引起振动和空气轴承本身固有微振动的衰减较慢,影响了系统的稳定性和测量准确性.为了解决这个问题,本文以小孔节流空气轴承作为研究对象,在其结构中部增设了类似空气弹簧的上下腔室和节流孔,当空气轴承振动时,压力空气在上下腔室之间流动,通过节流孔处的节流效应将振动能量衰减掉.根据这一构想,首先对新结构通过空气弹簧理论进行了初步优化设计,接着对新结构空气轴承和普通空气轴承进行了冲击响应实验,证实了新结构能够很好地起到快速衰减振动的作用,同时对微振动有良好的抑制效果,然后通过模态分析软件MEscope得到了空气轴承的阻尼比系数,发现新结构空气轴承阻尼比系数较普通结构空气轴承阻尼比系数有近一个数量级的提高.另外,还通过实验得到新结构空气轴承可以略微增加轴承的承载能力和刚度.

Aerostatic bearing has been used in many fields as an excellent guidance and carrying component for its properties of cleanness and near zero friction. Yet its low damping capacity in carrying direction leads to relatively slow depression of the vibration from outside and the natural micro vibration of the aerostatic bearing,which extremely affects the system＇s stability and measurement accuracy. This paper presents a new structure of aerostatic bearing with addition of a top chamber, a bottom chamber and orifices in the middle. When the aerostatic bearing vibrating induces the compressed air to go through the orifices between top and bottom chamber in reciprocating way, energy of vibration can be depressed by throttling effect. Theoretical research and impulse response experiments were taken on the proposed aerostatic bearing. Both demonstrate and verify its good performance of vibration reduction as well as microvibration depression. Modal analysis with MEscope of the experimental data shows that damping capacity of the new structure is improved by nearly 10 times compared with that of the traditional structure of aerostatic bearing. Besides, experiments indicate that the new structure increases carrying capacity and stiff- ness of the aerostatic bearing to some extent.