Bow型硅微加工缺陷对动压气体轴承动态特性的影响  

Influence of Bow Defect in Microfabrication on the Dynamic Performance of Hydrodynamic Gas Bearings

作　　者：张小青[1,2] 王晓力[2] 石文天[1] 刘玉德[1] 熊光洁[1] 

机构地区：[1]北京工商大学材料与机械工程学院,北京100048 [2]北京理工大学机械与车辆学院,北京100081

出　　处：《润滑与密封》2015年第12期29-36,共8页Lubrication Engineering

基　　金：北京工商大学青年教师科研启动基金项目(QNJJ2014-21);北京市教委科技发展计划面上项目(KM201110011008;KM201110011009;KM201510011004);北京市优秀人才培养资助项目(2013D005003000011)

摘　　要：受硅微加工技术的限制,微气体润滑径向轴承经常产生Bow型加工缺陷,带来气膜厚度沿轴向的不一致性。将存在Bow型加工缺陷的动压气体轴承的膜厚方程与超薄气膜润滑理论相结合,推导同时考虑硅微加工缺陷及稀薄气体效应的微气体轴承润滑方程,并采用Newton-Raphson方法进行求解。用"简正模"法推导系统的动特性系数及稳定性的求解模型,探讨硅微加工缺陷对轴承润滑特性及动力学特性的影响规律。结果表明,侧壁Bow型加工缺陷使得气膜中的压力分布变得平坦,降低系统的承载能力和气膜刚度,使临界质量曲线整体上移,增大轴承维持稳定运转所需的最小偏心率;此外,大偏心率时存在Bow型缺陷的轴承的高速性能差,增大轴承数有可能造成系统失稳,且缺陷程度越大,影响越明显。Due to the microfabrication limitations, the bow defect of the journal bearing defined by the clearance be- tween the rotor and static structure is inevitable.The bow defect leads to the variation of the clearance along the bearing length.The bowed gas film thickness equation was combined with the molecular gas-film lubrication model so that both the gas rarefaction effects and the bow effect were introduced simultaneously.The Newton-Raphson method was adopted to solve the nonlinear equations.The normal mode method was utilized to derive the mathematic model for assessing the dynamic properties and the stability charts of the micro gas bearing system.The results indicate that the bow effect lessens the pres- sure distribution of the gas film, weakens the load capacity and stiffness coefficients of the system, and increases the re- quired stable minimum eccentricity.The curves of critical mass value move upward compared with the ideal bearing with the same minimum clearance. Meanwhile, bearing systems with bow defect is more liable to become unstable for high bear-ing number and eccentricity than ideal bearings, and more influence will happen when the degree of bow defect becomes larger.

关 键 词：微气体轴承 加工缺陷 稳定性 稀薄效应 POWER MEMS 

分 类 号：TH117.2[机械工程—机械设计及理论]