A thermal EHL investigation for finite line contact under starved condition on bush-pin hinge pairs in industrial chains

During the operation of the industrial chains, serious starvation may happen so that the oil film is often too thin to effectively separate the bush-pin surfaces, resulting in surface damage of the pin since the bush surface is harder. In this paper, the effects of oil supply and equivalent radius of curvature on the variations of pressure, film thickness and temperature in the contact area are studied based on the thermal elastohydrodynamic lubrication (EHL) theory and a finite line contact lubrication model under oil starvation condition is employed. It is found that oil starvation and the increase of equivalent curvature radius will aggravate the stress concentration at the end of the contact area, and more oil supply is required in the contact area if the thermal rise is considered. An oil starvation mechanism of finite line contact EHL is proposed, in which in addition to the direct influence of oil supply, the interaction of film thickness, pressure and temperature in the contact area also play important roles. The reduction of minimum film thickness is proposed to measure the degree of oil starvation at the ends of the contact area. The oil starvation process of finite line contact is divided into four typical stages.