Establishment of method to observe EHL film thickness and its behavior in commercial steel rolling bearing by ultrasonic interference method

为了使在恶劣条件下运行的滚动轴承稳定运行，重要的是观察在轻微固体接触条件下的弹流润滑膜厚度及其行为。因此，对于不透光的真实的滚动轴承，仅通过常规的光学观察是不够的，必须弄清其弹流润滑区域的润滑状况。本研究的目的是提出一种新的测量小于100 nm弹流润滑油膜厚度的超声脉冲反射法，建立了一套可用于工业钢轴承弹流润滑膜厚及其行为的测量系统，用50MHz探头在常压下测量了超声波的反射特性，在超声波辐照区域内对回波高度进行平均，得到的油膜厚度雅阁与理论结果相符，并测量了已知油膜厚度时回波高度与油膜厚度的关系， 关于我们 绘制红色和校准曲线。当利用该校准曲线进行静态条件下的膜厚估计时，可以清楚地看出，可以估计小于100nm的膜厚。通过使用由光学玻璃和钢球组成的单核细胞型EHL装置的超声波方法观察到的回波高度中的形状分布，与光干涉法观察到的弹流润滑膜的形状定性一致。当使用钢盘进行类似实验时，能够观察到通常通过光干涉法观察到的马蹄形油膜。此外，速度和载荷对弹性液体润滑膜形成的影响符合一般趋势，并且确认了通过超声波法测量弹性液体润滑膜厚度的可能性。此外，直到直接固体接触为止的膜厚度行为从推力轴承装置开始，该装置具有停止滚珠旋转的功能，并且可以评估商用滚动轴承的润滑状况，观察了结果，确认了商用轴承的弹流润滑膜厚分布与扁钢圆盘的弹流润滑膜厚分布相同。如上所述，确认了利用超声波法评价商用轴承的弹流润滑条件的可能性，为技术开发奠定了基础。少

For the stable operation of a roll bearing operated with severe condition, it is important to observe an EHL film thickness and its behavior under the condition that solid contact slightly occurs. Therefore, it is insufficient only by conventional optical observation and must clarify the lubrication conditions of EHL region for real roll bearing which does not transmit the light.The purposes of this study were proposal of a new measurement method of oil film thickness for the EHL film less than 100 nm by ultrasonic pulse reflection method, and establishment of the new measurement system which can observe the EHL film thickness and its behavior for commercial steel bearing.Relations of reflection characteristic of ultrasonic wave, measured under atmospheric pressure with 50MHz probe, and the oil film thickness accord with the theory result which is made echo height average in ultrasonic wave irradiation area.In addition, the relations of echo height for a known film thickness were measu … More red and calibration curves were made. When the estimation of a film thickness under the static condition with this calibration curve was done, it became clear that film thickness estimation of less than 100nm can be possible.The distribution of the shape in echo height observed by a ultrasonic wave method with the monocyte type EHL apparatus, which consisted of optical glass and a steel ball, agreed with the shape of EHL film observed by light interference method qualitatively. When the similar experiment using steel disc was performed, the horseshoe-shaped oil film, which is generally observed by light interference method, was able to observe. In addition, the influence of speed and load for the formation of the EHL film accorded with a general tendency, and the possibility of the EHL film thickness measurement by a ultrasonic wave method was confirmed.Furthermore, the behavior of a film thickness until direct solid contact start with a thrust bearing apparatus, which has a function stopping the revolution of balls and can evaluate lubrication conditions of a commercial roll bearing, was observed. As a result, it was confirmed that the behavior of EHL film thickness distribution of a commercial bearing was same with the behavior observed by a flat steel disc.As mentioned above, the possibility of the evaluation of EHL lubrication conditions for the commercial bearing by an ultrasonic wave method was confirmed, and the base for technology development was established. Less