超声法测量圆柱滚子轴承润滑油膜厚度
Measurement of Lubricant Film Thickness of Cylindrical Roller Bearing Using Ultrasound

针对实际工况下圆柱滚子轴承接触区润滑油膜薄而窄难以测量的问题,利用基于等效弹簧模型的超声测量原理进行研究,设计并搭建了专用圆柱滚子弹流润滑油膜厚度测量实验台,对超声测量圆柱滚子轴承润滑油膜厚度进行实验研究。通过该实验台来模拟圆柱滚子在实际工况下的运行状态,高频测量探头安装在5自由度微动平台上以便调整合适的测量位置;在轴承保持架上贴一个反光片作为每个工况下开始测量的触发信号,保证每次测量同一个滚子;使用温度传感器实时测量实验轴承温度,考虑温度对润滑油的影响。实验所能测量的最大转速取决于重复频率,重复频率不足会导致较大的测量误差;超声探头聚焦直径区域内的平均效应导致无法测量比聚焦区域更小的油膜分布信息。在最高转速600 r/min、最大载荷16 kN的范围内成功测量到了圆柱滚子轴承在实际工况下0.2~1.2 μm的膜厚。实验结果表明:最小膜厚会随转速的升高而增大,随载荷的增大而减小,与理论计算结果拟合程度较高,证明了该方法在实际工况下测量圆柱滚子轴承油膜厚度的有效性和准确性。
The rollers and raceways in cylindrical roller bearings are separated by an extremely thin lubricant film in a narrow region, which is difficult to measure directly in actual working conditions. A cylindrical roller bearing oil film experiment platform is established in this study, and the method to measure the elastohydrodynamic lubrication film thickness in the contact area between the roller and outer raceway in actual working conditions is experimentally researched based on the principle of stiffness equivalence. The experiment platform is used to simulate the running states of a cylindrical roller bearing in actual working conditions, and a 50？？MHz focus ultrasonic transducer is fixed on a micro？？motion platform with 5？？DOF so as to adjust the measuring position. A reflecting plate is pasted on the bearing cage to trigger the measurement so that the same roller can be measured at each time. A thermocouple is used to measure the bearing temperature. The maximum rotational speed that can be measured depends on the pulse repetition rate (PRR), and low PRR will cause measurement errors. The averaging effect of the transducer in its focal zone makes it hard to pick out the detail of the film thickness in the contact area. Oil films between 0.2 μm and 1.2 μm are measured in actual working conditions under a maximum speed 600 r/min and a maximum load 16 kN. Experimental results show that the thickness increases as the shaft speed increases, and decreases as the radial load increases. The correctness and effectiveness of the proposed method are proved through a comparison between the experimental results and theoretical values