Stress Analysis in Surface Durability Tests of Sintered Steel Gears with Different Densities Using FE-simulation Considering Voids

摘要

Gear-running tests were first carried out using case-carburized pre-alloy sintered steel spur gears with different densities of 7.40 g/cm~3 and 7.54 g/cm~3. The load bearing capacities of as-sintered gears with a density above 7.40 g/cm~3 almost matched those of case-carburized Cr-Mo wrought steel gears. The surface fatigue durability was increased by 5–15 % by gear surface rolling, whose effect was more remarkable for P/M gears with a lower density. These experimental results were then analytically investigated by examining the contact stress distributions around the operating pitch point of P/M pinion using a simplified two-dimensional finite element model considering voids. The peak of the maximum shear stress τ_(max) decreased as the amount of fully densified depth δ increased, and there was only a slight difference in the distribution profile of τ_(max) for every P/M pinion when δ reached 0.3 mm. These simulation results appear to explain the gear-running test results well.