Load-carrying Capacity of the HB〓340 (Hardened and Tempered) Gears : 4th Report, Effect of Surface-finishing on Surface Durability

Abstract

In the previous reports, in order to obtain high surface durability of the H_B ≈ 340 (hardened and tempered) gears, the authors proposed that the initial tooth surface should be finished as smooth as possible. In this report, surface durability of gears finished by various methods (skiving --- finish-hobbing with carbide tipped hob, honing with screw-type hone, lapping and grinding) are compared with that of hobbed gears by using a power circulating-type gear testing machine. From these results, it is found that the smoother the surface, i) the less the number of pits and the smaller their size, ii) the smaller the rate of increase of pits with repeated contact stress, and iii) the higher the load-carrying capacity. Therefore, the influence of surface roughness on the surface durability is much more clarified, and the effect of various surface finishes can be grasped quantitatively.