Synergistic effects of surface strengthening and surface micro-texture on aviation spherical plain bearing tribological properties

With an increase in extreme and complex work conditions in the fields of aircraft industry and high-speed train, single surface strengthening or single surface machining is not satisfactory with repeated requests of spherical plain bearings, which results in serious wear. Therefore, in this paper, a compound method of ultrasonic surface rolling process and surface texture was proposed on the basis of investigating the wear mechanism to meet the tribological property requirements of spherical plain bearings. The theoretical and experimental results show that low micro-hardness and low shear strength of surface material, rough surface, and poor lubrication are the important factors contributing to the wear of spherical plain bearings. The surface roughness Ra and Rz of processed spherical plain bearings are reduced to 0.02 µm and 0.14 µm from 0.35 µm and 2.1 µm, respectively, and the micro-hardness of surface material is increased by about 20%. The double-sine micro-textures with the width of 120 µm and the depth of 20 µm produced by laser machine, together with the circular groove, provide satisfactory lubrication for the spherical plain bearings. Finally, the wear resistance properties of spherical plain bearings were increased by more than 55%. The proposed synergistic methods have great advantages in improving the tribological properties of key fundamental components, especially for spherical plain bearings.