Abstract:

In a working environment containing particles media, the thermo-mechanical coupling deformation and friction and wear of mechanical seal ring made of hard materials play an important role in the leakage and service life of mechanical seal. In this paper, the friction between the ring and the abrasive is considered, the friction coefficient is measured by experiments, and the finite element calculation model of thermal mechanical coupling between the ring and the abrasive is established. The temperature field and end face deformation of WC-Co cemented carbide and SSiC ceramic seals are studied, and the variation of seal clearance under different working conditions is analyzed. The temperature, leakage and surface roughness of the seal ring before and after wear were tested and analyzed. The wear mechanism of the end face was discussed, and the accuracy of the calculation model was verified. The results show that the finite element model considering the friction heat of the moving ring can accurately predict the temperature and face deformation of the seal. Under the coupling effect, the outer diameter of the moving and static ring disconnects and the inner diameter fits, and the degree of deformation difference increases with the increase of pressure difference and speed. Deformation results in uneven distribution of wear marks on the end face and serious wear marks on the inner diameter. The end face of the WC-Co cemented carbide matched sealing ring has small deformation and small leakage. The high-hardness WC particles can produce a good “shadow response” to the Co matrix, and have good wear resistance. The toughness of SSiC ceramic material is poor, and it is easy to produce flake-shaped wear debris, and form transitional abrasive wear. The wear resistance of the material is poor, and the leakage increase is obvious. Under abrasive condition, WC-Co cemented carbide mechanical seal has the characteristics of small leakage and high wear resistance. The results provide a reference for the material application and design optimization of mechanical seals in granular media.

Key words: mechanical seal, thermo-mechanical coupling, simulation, attrition, granular materials, hard material

摘要：

在含有颗粒介质的工作环境中下，硬质材料配对机械密封环的热力耦合变形和摩擦磨损对机械密封的泄漏和使用寿命起着至关重要的作用。考虑动静环和颗粒介质的摩擦，试验测定了摩擦系数，建立了动静环热力耦合的有限元计算模型，研究了WC-Co硬质合金和无压烧结碳化硅（SSiC）陶瓷两种硬质材料密封的温度场和端面变形规律，分析了不同工况下的密封间隙变化规律。试验测试分析了密封环温度、磨损前后的泄漏及表面粗糙度，讨论了端面的磨损机理，验证了计算模型的准确性。结果表明：考虑动环磨粒摩擦热的有限元模型能准确地预测密封的温度和端面变形；耦合作用下动静环端面呈现外径脱离、内径贴合的变形，且变形差异程度随压差和转速的增大而加剧；变形导致端面磨痕分布不均匀，内径磨痕较严重。WC-Co硬质合金配对密封环的端面变形小、泄漏量小，高硬度WC颗粒对Co基体能产生很好的“阴影效应”，具有良好的耐磨粒磨损性能。SSiC陶瓷材料韧性差，易产生片状磨屑，形成过渡型磨粒磨损，材料耐磨性较差，泄漏量增加明显。在磨粒工况下，WC-Co硬质合金机械密封具有泄漏小、耐磨性强的特点。研究结果为颗粒介质中机械密封的材料应用及设计优化提供了参考。

关键词: 机械密封, 热力耦合, 模拟, 磨损, 颗粒物料, 硬质材料