Advanced Design of Worm Wheels Made of Dissimilar Materials

In order to provide the necessary wear and friction features in a worm gear, the worm wheels are often made of specific material, mainly bronze. Considerable material cost reduction is achieved by substituting the inner part of the wheel by a steel hub, which is joined with the bronze toothed rim by various means. In this paper, results of research to the optimum design and production of the wheel welded by the electron beam technology are presented. Namely, the crack distribution in the weld and residual stresses in the whole wheel were invetigated and an improved welding technology along with a modified weld geometry were proposed to eliminate the cracks considerably. The new welding technology is also applicable to gear wheels made of similarly related material combinations.