Influence of housing hole accuracy on the starting torque of self-lubricating spherical plain bearings

Abstract

The accuracy of the housing hole mainly refers to the dimensional tolerance, ovality and surface roughness of the hole, which directly affects the swing flexibility and service life of the self-lubricating spherical plain bearings (SSPBs) after the bearing is fitted in the housing hole. The dimension tolerance between the bearing and the housing has been ordained in the aviation standard. However, it is found that the ovality and surface roughness of the housing hole also have a great influence on the interference fit state, thus affecting the starting torque. In this paper, the effects of the three indexes of the housing hole accuracy (dimensional tolerance, ovality and surface roughness) on the starting torque were studied. Firstly, a theoretical analysis of the liner deformation inside the bearing was carried out based on the Lame equation. Then, the concept of equivalent interference was proposed considering the interference fit caused by the ovality and surface roughness, and the amount of the equivalent interference was determined. Furthermore, the influences of the three indexes on the starting torque were studied quantitatively with theoretical solution, numerical analysis and experimental verification. The results showed that the proposed concept of the equivalent interference can analyze the influence of the ovality and the surface roughness effectively, and the ovality has a greater effect on the starting torque than the surface roughness. The three precision indexes of the housing hole are reasonably designed to ensure that the starting torque after fitted meets standard requirements.