Surface integrity and transmission performance of spiral bevel gears subjected to shot peening: A comparison between concave and convex surfaces

Abstract

As a typical surface strengthening method, shot peening can effectively enhance the bending fatigue resistance of spiral bevel gears by improving the surface integrity parameters. Due to the complex geometry of spiral bevel gears, one group of shot-peening parameters can hardly satisfy the performance requirements of concave and convex surfaces. Thus, the effect mechanism of shot peening on both surfaces needs a thorough understanding. Meanwhile, the effect of shot peening on the transmission performance of gears is still somewhat cloudy and controversial, which confuses the optimization of shot-peening parameters. To address this issue, the effect of shot peening on the surface integrity and transmission performance of spiral bevel gears is systematically investigated by experiments. The results show that due to the smaller curvature radius, the surface integrity of the concave surface is better than that of the convex surface before and after shot peening. Specifically, for the shot-peened gears, the dislocation density at the concave surface is 9.1 % higher than that at the convex surface; the intergranular oxidation (IGO) layer for the concave surface is 2.1 % shallower than that for the convex surface; the maximum compressive residual stress for the concave surface in the profile direction is 6.9 % higher than that for the convex surface; the peak value of hardness for the concave surface is 3.5 % higher than that for the convex surface. Furthermore, smoother tooth flanks can lead to better transmission performance of gears, and shot peening has side effects on it. The transmission performance in the drive condition is better than that in the coast condition before and after shot peening.