Influence of Impact Load on Fatigue Bending Strength of Case-Hardened Gears

抄録

In this paper, the authors investigated the relationship between case-hardening condition and the bending fatigue strength of gear tooth under impact load. The results obtained from this experiment are summarised as follows: (1) There exists an optimal thickness of case-hardened layer for bending endurance limit of case-hardened gears, but it differs from an optimal thickness of case-hardened layer for impact bending strength. And an excessively large thickness of case-hardened layer causes an decrement of impact bending strength. (2) When impact load P is less than 0.63P_im' (P_im': impact fracture load), and impact velocity is below 5m/sec such as in this experiment, impact load has no influence on fatigue strength. (3) Few times applications of an impact load, which is nearly equal to endurance limit load, cause an increment of bending endurance limit.