异向卷吸作用下润滑剂回填增强效应试验研究

Experimental Investigation into Enhancement of Lubricant Replenishment Induce by Angled Entrainment

试验研究了异向卷吸作用对润滑剂回填增强效应和成膜特性的影响。采用球-盘点接触光干涉油膜测量仪,通过控制钢球运动方向产生卷吸速度与滑动速度呈夹角的异向卷吸作用。试验发现,限量供油条件下异向卷吸与同向卷吸相比,接触区入口供油状态得到明显改善,其特征是在入口区产生了与经典乏油工况不同的充盈油池,该油池的出现使油膜厚度接近于充分供油下油膜厚度。试验观察了不同角度、速度、供油量和黏度下的入口油池外形及非对称性油膜特征。接触副表面上侧带与滚道重叠并被卷吸到入口区,是入口油池形成的主要机制;热黏度楔效应是诱发油膜外形非对称性的原因;入口剪切热、侧泄、接触区热量向入口区迁移和剪稀效应,是润滑油膜厚度随角度减小的原因。试验结果表明,将经典的乏油边界条件应用于异向卷吸工况具有局限性。

The enhancement of lubricant replenishment and film formation induced by angled entrainment effects are investigated.Using ball-on-disc optical apparatus,angled entrainment is formed by adjusting the motion direction of steel ball which could induce different angles between entrainment and sliding velocities.Comparing with the situations of entrainment in the same directions under fixed amount of oil feeding,it is found that the inlet lubricant supplying conditions are significantly improved,characterized by the appearance of a remarkable inlet oil reservoir.This reservoir pushes the film thickness approach the fully flooded states,which is quite different with the situations of traditional starved contacts.The patterns of inlet reservoir varying with angles,velocities,oil feeding amounts and viscosities,as well as the asymmetry film shapes are investigated.The main mechanisms resulting in the inlet oil reservoir was the delivery of overlapped side bands into the inlet conjunctions.The effect of thermal wedge viscosity is response for the distorted film shape.The reduction in film thickness with angle increasing is attributed to the inlet shear heating effect,side leakage,inflow of heat from contact zone into inlet zone and shear thinning effect.The observations suggest the tradition boundaries under starvation are limited to be applied to present situations.