Effect of nitrile butadiene rubber hardness on the sealing characteristics of hydraulic O-ring rod seals

目 的 研究丁腈橡胶硬度对O形液压杆封静/动态密封性能的影响, 为其工程中橡胶硬度的选型提供理论参考. 创新点 1. 基于混合弹流润滑模型, 分析了丁腈橡胶硬度对O形液压杆封静/动态密封性能的影响; 2. 以低泄漏、 低摩擦为目标, 获得了静/动态应用下丁腈橡胶O形液压杆封的橡胶硬度优选范围. 方 法 1. 通过数值分析静接触压力、 von Mises应力、 最小液膜厚度、 泄漏率和摩擦力, 揭示丁腈橡胶硬度对O形液压杆封静/动态密封性能的影响机理; 2. 以最大静接触压力和最大von Mises应力作为静密封性能评价指标, 以及以净泄漏量和摩擦功耗作为动密封性能的评价指标, 确定丁腈橡胶O形液压杆封的最佳橡胶硬度值. 结 论 1. 随着橡胶硬度的增加, 丁腈橡胶O形液压杆封的抗变形能力增强, 静接触压力增大, 最小液膜厚度减小, 泄漏量减小, 摩擦力增大; 2. 低硬度密封易产生挤出效应和应力集中现象, 因此更适合在高速或低密封性要求的场合使用; 3. 高硬度密封具有更优的静/动态密封性能, 所以特别适用于高压工况场合, 但由于其摩擦力较大, 因此在满足泄漏要求的前提下应尽量选择相对较低的橡胶硬度以减小摩擦. The nitrile butadiene rubber (NBR) hardness effect on the sealing characteristics of hydraulic O-ring rod seals is analyzed based on a mixed lubrication elastohydrodynamic model. Parameterized studies are conducted to reveal the mechanism of the influence of rubber hardness on the static and dynamic behavior of seals. The optimized selections of rubber hardness are then investigated under different conditions. Results show that the low hardness seal is prone to stress concentration due to the extrusion effect under high pressure conditions; it is also more prone to leaking. A high hardness seal can better prevent leakage by reducing film thickness but it will cause large frictional power loss and increase the probability of wear failure. The choice of low hardness is recommended to reduce friction with the premise that leakage requirements are met.