A computer system for tooth root optimization of case-hardened gearwheels

Today, shape optimization methods allow the minimization of the maximum stress occurring in the tooth root under load. For homogeneous material characteristics, as they are found in quenched and tempered steel, this is expected to result in similar increases in load carrying capacity. Highly loaded gearwheels are frequently case-hardened to achieve depth-dependent strength gradients, increasing from the core to the surface. Furthermore, load-reducing compressive residual stresses are induced within the surface layer. For case-hardened components, the reduction in maximum stress does not necessarily lead to an equivalent increase in load carrying capacity. In order to directly maximize the load carrying capacity of a gearwheel instead of minimizing the load stresses a computer system is developed which considers local strength as well as residual stresses.