Study on fatigue life improvement of press-fit bushing strengthened ear hole

Addressing the challenge of correlating extrusion amount with strengthening effects in cold extrusion-strengthened ear holes of press-fit bushings, this study examines the cold extrusion process for large-diameter ear hole bushings. Firstly, a finite element model was developed to simulate cold extrusion reinforcement, analyzing residual stress and hole wall deformation under varying extrusion amounts. Then, the finite element model was used to analyze the mapping relationship between the fatigue life of the ear piece and the extrusion amount. The reliability of the finite element model of the cold extrusion reinforced ear hole of the press-fit bushing was verified by the cold extrusion installation experiment of the press-fit bushing and the stress detection experiment of X-ray diffractometer. Finally, an improved cold extrusion strengthening process for press-fit bushings was proposed, and its effectiveness was verified by the finite element method. Results demonstrate that the strengthening effect of cold extrusion does not exhibit a positive correlation with extrusion amount; instead, it reaches a peak at a specific value. The enhanced cold extrusion process effectively addresses uneven deformation in the ear hole, thereby enhancing its fatigue life.