油水两相流润滑轧机油膜轴承的摩擦行为分析

目的研究含水润滑油对轧机油膜轴承的摩擦学性能的影响。方法选取轧机油膜轴承为研究对象,利用油水两相流体数学模型和弹流润滑方程研究轧机油膜轴承在等温条件下的润滑特性,分析油水两相流体润滑膜的压力、膜厚分别随含水率、滑滚比、轴颈间隙、主轴转速和轧制力的变化关系。结果水介入润滑油之后,随着含水率的增加,油水两相流体的黏度先增加,在含水率为30%左右时达到最大值(0.08 Pa·s),之后又迅速减小,直至接近于纯水的黏度(0.001 Pa·s)。当含水率为30%时,无量纲膜厚达到最大值(0.82),当含水率为90%时,无量纲膜厚达到最小值(0.68)。结论随着含水率的增加,油水两相流体由油包水流型转化为水包油流型,压力变化不大,膜厚先增加后减小,作为润滑剂,油包水流型比水包油流型具有更好的润滑性能,且在流型转变点处的润滑性能最优。随着滑滚比和轧机油膜轴承主轴转速的增加,压力减小,承载能力减弱,膜厚增加,润滑性能增强。随着轴颈间隙和外部轧制力的增加,压力增加,承载能力增强,膜厚减小,润滑性能减弱。

Friction Behavior of Oil Film Bearing in Oil-water Two-phase Flow Lubricated Rolling Mill

The work aims to study the effect of water presence in oil on the tribological properties of oil film bearing. The oil film bearing of rolling mill as the object of study was established by mathematic model of oil-water two-phase flow and equation of elastohydrodynamic lubrication under isothermal conditions, so as to study the lubrication properties of oil film bearing in rolling mill, and the variation relationship betwwen pressure & film thickness of oil-water two-phase fluid lubrication film and water content, slip ratio, journal gap, spindle speed, rolling force. With the increase of water content after charging lubricating water, viscosity of the oil-water two-phase flow first increased and reached a maximum (0.08 Pa·s) at a water content of about 30%, then decreased rapidly until reducing to viscosity of pure water (0.001 Pa·s). Dimensionless film thickness reached the maximum (0.82) at waster content of 30% and the minimum (0.68) at 90%. As water content increased, the oil-water two-phase fluid transformed into oil-in-water flow pattern from water-in-oil flow pattern with minor pressure change, film thickness first increased and then decreased. Compared with oil-in-water flow pattern, water-in-oil flow pattern as a lubricant provided better lubricating performance and optimal performance at transition point of flow pattern. With the increase of slip ratio and spindle speed of oil film bearing, pressure and carrying capacity decrease while film thickness and lubrication performance increase. With the increase of journal gap and external rolling force, pressure and carrying capacity increase while film thickness and lubricating performance decrease.