Process of Durability Improvement of Gear Tooth Flank Surface

Author:  Roman Cisek; Jeffrey Brengle Finn
Source:  US Patent 8,062,094
Doc ID:  2011137
Year of Publication:  2011
Abstract:  
Pinion gears for planetary gear transmissions are hobbed, heat treated, and then ground to get better control of the leads/profiles on all the gear teeth. Then a light shot peening is applied to the tooth flanks to achieve the desired compressive residual stresses on the tooth surface . By applying the process in the controlled manner specified, the surface is not over-cold worked. Next, a chemically assisted isotropic surface treatment is applied over the pinion gears to improve the surface finish on the gear teeth. For low speed applications the surface finish improves the lambda ratio, allowing for a good oil film thickness on the surface of the gear teeth.