Analysis Of Lubrication Performance In Cylindrical Roller Bearings Considering Surface Defect

Rolling bearings are important and foundational components for all types of machinery and equipment. Its precision, performance, life and reliability play a decisive role in application.Therefore, cylindrical roller bearings have been investigated in this paper, and the effects of the surface scratch, bump and dent on the lubricating performance in bearings have been provided, and the lubricating status transitions were studied by experiment.First of all, a model was built for a roller with a scratch and an infinite plane contact and a full numerical solution was obtained for the steady state isothermal finite line contact problem. Effects of scratch shape, depth and width was analyzed.Results show that, different shapes of the surface scratch have different influence on the lubricating status for a roller. The rectangular shape has greatest impact, followed by the cosine shape, triangular shape with minimal impact; An increase in the depth or the width of the scratch will worsen the lubrication on both sides of the scratch, and easily cause local wear for a roller pair.Secondly, the transient elastohydrodynamic lubrication model between a roller with a surface defect and an inner or outer ring in rolling bearings has been established, and the effects of the style,the size, the load and the speed of a single surface defect on the lubricating performance for a roller-ring contact was discussed.Based on this, the interaction impact of two surface defects on the lubricating performance was studied. Results show that, the surface bump causes the local pressure increases and the local film thickness decreases; the surface dent results in the local pressure decreases and local film thickness increases. In additional, when the surface bump moves to the position of the film outlet constriction, the lubricating condition becomes worse.Variations in the size, the load and the speed lead to the change of the film thickness and pressure. In comparison with the single defect,effects of the two defects on the lubricating performance are larger.Finally, the optical interference experimental of design for a lubricating status transition of finite line contact was made, and the film shape and film thickness were measured with different load and speed. Results show that, with the increase in the entrainment velocity or the decrease in the load, the lubricating status between a roller and disc contact gradually changes from EHL to hydrodynamic lubrication, and a middle status exists during the process of the two lubricating status.