Study on Elastohydrodynamic Lubrication of Undulatedly Roughened Elastomer Surfaces

对商用唇型油封进行了试验，观察了在磨合过程中接触的弹性体唇部的微波动发展情况。将微起伏复制成硬复制品，通过扫描轮廓术测量其高度和节距，根据测量的轮廓线，制作了几种表面起伏放大的模型密封，以演示唇面和轴面之间的弹流润滑和密封机理。一个由玻璃制成的中空轴被用来可视化油膜的创作。通过测量通过油膜衰减的唇面反射光的强度，利用新研制的装置估算了油膜厚度，并对真实振幅和波长正弦波动的油膜形成进行了数值分析，其中轴面假设为刚性和光滑。结果表明，在没有轴旋转的静止状态下，弹性体唇面的起伏很容易变平，从而确保在正常接触压力下具有良好的密封性。对于以足够速度运行的轴，随着油膜的产生，扁平的唇面恢复了30%-40%的起伏。数值模拟的结果与以往报道的商用唇型油封的特性相吻合。

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.