Study on Elastohydrodynamic Lubrication of Undulatedly Roughened Elastomer Surfaces

对商用唇型油封在磨合过程中接触弹性体唇部的微波动进行了试验研究。将微波动复制成一个硬复制品，用扫描轮廓术测量微波动的高度和俯仰。根据实测曲线，制备了几种按比例放大表面波动的模型密封件，以演示唇部和轴表面之间的弹性流体动力润滑和密封机理。一个由玻璃制成的中空轴被用来可视化油膜的创作。利用新研制的仪器，通过测量从唇面反射的光穿过油膜衰减后的强度，估算出油膜厚度。在假定轴表面为刚性光滑的条件下，对真实振幅和波长正弦波动的油膜形成进行了数值模拟。结果表明，在无轴转动的平稳状态下，弹性体唇面波动容易被压平，以保证在通常接触压力下的良好密封性。对于以足够速度运行的轴，随着油膜的形成，扁平的唇面恢复了30- 40%的波动。这些数值模拟结果与先前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.