Research on tribological properties of wedge-shaped convergent texture on crankshaft

In order to reduce the friction loss of internal combustion engine, this paper takes 42CrMo forged steel as the research object, and uses femtosecond laser to prepare wedge-shaped convergent micro-textures with different shapes (triangle, square, circle) and convergence angles (3°, 5°, 7°). The tribological properties were investigated by multi-condition friction and wear test and crankshaft single-turn bench test. The results show that the friction reduction effect of texture under oil lubrication condition is remarkable. The maximum friction reduction rate at room temperature is 21.7%, the high temperature is 34.8%, and the square texture with 7° convergence angle is the best. The three textures have the best convergence angle, which is delayed by the increase of lubricating oil fluidity at high temperature. In dry friction, the texture reduces friction by storing wear debris. In oil lubrication, the friction is reduced by hydrodynamic pressure and ”secondary lubrication”, and the wear resistance of triangular texture is better. The textured crankshaft journal does not affect its fatigue life and can effectively reduce friction. This study provides key support for the engineering application of wedge-shaped convergence texture on crankshaft.