Effects of Roller Geometry on Contact Pressure and Residual Stress in Crankshaft Fillet Rolling

In this paper, the effects of roller geometry on contact pressure and residual stress in crankshaft fillet rolling are investigated by a two-dimensional finite element analysis. The fillet rolling process is first introduced to review some characteristics of the rolling tools. A two-dimensional plane strain finite element analysis is then employed to qualitatively investigate the influence of the roller geometry. Computations have been conducted for eight different contact geometries between the primary roller and the secondary roller to investigate the geometry effect on the contact pressure distribution on the edge of the primary roller. Fatigue parameters of the primary rollers are also estimated based on the Findley fatigue theory. Then, computations have been conducted for three different contact geometries between the primary roller and the crankshaft fillet to investigate the geometry effect on the residual stress distribution near the crankshaft fillet. The results suggest that the contact geometry between the two rollers has significant influence on the contact pressure distribution and the maximum contact pressure along the edge of the primary roller and, consequently, the fatigue lives of the primary rollers. The results also suggest that the contact geometry between the primary roller and the crankshaft fillet does not have significant influence on the overall residual stress distribution and, consequently, may not have significant influence on the fatigue performance of crankshaft sections under bending loads. Therefore, an appropriate adjustment of the contact geometry between the two rollers can significantly improve the fatigue lives of the primary rollers without a significant change of the overall residual stress distributions near the crankshaft fillet and, in turn, the fatigue performance of crankshaft sections under bending loads.