真空预载型多孔质气体止推轴承静态特性研究

Research on Steady State Characteristic of Vacuum Preload Porous Aerostatic Thrust Bearing

为了提高孔质静压气体轴承的刚度,将负压腔引入多孔质静压气体止推轴承的设计中,运用有限元方法对真空预载型多孔质静压气体止推轴承进行数值分析,分析负压腔真空度、负压腔面积比S_a/S(负压腔横截面积与轴承横截面积比值)、多孔材料渗透率、供气压力等因素对轴承静态特性的影响。分析结果显示:负压腔中真空度的变化对轴承的刚度几乎没有影响;真空度的增大,改变了气膜的压力分布造成轴承承载能力在一定程度上的下降;在气膜间隙5～12μm之间,真空腔的引入使气膜刚度明显增加;当S_a/S≠0,气膜间隙8～10μm时,S_a/S值的变化对轴承承载能力的影响较刚度更大;在一定承载能力下,轴承刚度随负压腔面积比增大而增大,而气膜厚度随之逐渐减小。试制真空吸附型多孔质静压气体止推轴承,并对其承载能力、刚度进行试验,实验值和理论值有较好的一致性。

The porous aerostatic thrust bearing with vacuum chamber was numerically analyzed using the finite element method.The effects of the following factors on steady state characteristics of bearing were analyzed,such as the vacuum degree of vacuum chamber,vacuum chamber area ratio S a / S (the ratio of bearing cross section area),the permeability of the porous material and the supply pressure.The analysis results show that the change of the vacuum degree in the vacuum chamber has almost no effect on the stiffness of the bearing.The increase of the vacuum degree changes the pressure distribution of the film and causes the bearing capacity decrease in certain case;When thickness of film is between 5 and 12 μm,the introduction of the vacuum chamber increases the stiffness of the film significantly.When S a / S ≠0 and the film gap is between 8 and 10 μm,the change of the S a / S value has more influence on bearing capacity than that of the stiffness. Under the certain bearing capacity,the bearing stiffness is increased with vacuum chamber area ratio,and the film thickness is gradually decreased.Trial-produced porous aerostatic thrust bearing with vacuum chamber and its bearing capacity and stiffness were tested.The experimental values and theoretical values are in a good agreement.