Study on Elastohydrodynamic Lubrication of Undulatedly Roughened Elastomer Surfaces

对商用唇式油封进行了试验，观察了在磨合过程中接触的弹性体唇上的微波动发展。利用扫描轮廓仪测量了微波纹的高度和螺距，并根据测量结果制作了几种微波纹密封模型，以验证密封唇与轴之间的弹性流体动力润滑和密封机理。使用由玻璃制成的中空轴来可视化油膜的产生。利用新开发的测量装置，通过测量光在油膜中的衰减来估算油膜厚度，并对实际振幅和波长的正弦波动进行了数值分析，其中轴表面假定为刚性和光滑的。结果表明，在轴不转动的静止状态下，弹性体唇面的起伏在通常的接触压力下容易被压平，从而保证良好的密封。对于以足够的速度运转的轴，平坦的唇缘表面随着油膜的产生而恢复其30- 40%的波动。数值模拟的结果与文献报道的商用唇型油封的性能一致。

Commercial lip-type oil seals were tested to observe micro-undulation developing on the elastomer lips in contact during run-in process. The micro-undulation was duplicated into a hard replica and its height and pitch were measured by means of scanning profilometry.Following the measured profile, several types of model seals whose surface undulation was scaled up were prepared to demonstrate the elastohydrodynamic lubrication and sealing mechanisms between the lip and shaft surfaces. A hollow shaft made of glass was used to visualize the oil film creation. The film thickness was estimated by means of newly developed eccuipment based on the measurement of strength of the light reflected from the lip surface which is decaying through the oil film.Numerical analyses were also carried out to simulate the oil film creation for sinusoidal undulation of realistic amplitade and wave length, in which the shaft surface was assumed rigid and smooth. The results showed that, for a stationaiy state without shaft rotation, the undulation of elastomer lip surface was easily flattened to ensure good sealing under usual contact pressure. For a shaft running at sufficient speed, the flattened lip surface recovered its undulation by 30-40 % accompanying the oil film creation. Those results of numerical simulation agreed with the behavior of commercial lip-type oil seals reported previously.