基于微凸体侧接触模型的机械密封端面混合摩擦热理论预测

Theoretical Prediction of Mixed Frictional Heat of Mechanical Seals Based on Shoulder-shoulder Contact Model of Asperities

基于微凸体侧接触模型,推导了机械密封端面混合摩擦热计算式,研究了转速、摩擦间隙和粗糙度对常用机械密封端面混合摩擦热的影响。结果表明:常用混合摩擦状态下的机械密封端面微凸体接触多为第II类弹塑性接触;当转速ω?2 800r/min时,微凸体接触摩擦热所占比重较大,但随着转速上升,黏性摩擦热比重逐渐增大至百分之百;随着摩擦间隙d的增大,黏性摩擦热和微凸体接触摩擦热曲线均呈下降趋势,当d?2.8σ时,微凸体接触摩擦热减小至零,而黏性摩擦热随d变化不大;随着粗糙度的增加,端面摩擦热先下降后上升,在近1.6μm处最小,因而在机械密封设计时,存在某一粗糙度使混合摩擦热最少。

Based on shoulder-shoulder contact model of asperities, mixed frictional heat expressions of mechanical seals are derived. The influences of rotational speed, friction gap and roughness on the frictional heat are also investigated. The results show common mechanical seals in mixed lubrication mostly operate with second elastic-plastic contact. The frictional heat from asperity contact takes more proportion of total frictional heat when ω ？ 2 800 r/min is presented, but the viscous part gradually rises as the rotational speed increases and eventually equals to the total. Also, with the increased friction gap, the asperity and viscous frictional heat both decrease, however the former decreases to zero when d ？ 2.8σ while the latter changes little. As the roughness of seal end faces increases, the total frictional heat dramatically falls first and then tends to invariable, which indicates it is profitable for reducing mixed frictional heat to properly increase the roughness on seal end faces.