Development of rotation mechanism for improving fatigue strength by multifunction cavitation

Abstract

Cr-Mo steel (SCM420H) is used as the gear material for automobiles, and shot peening is applied as a processing method for increasing strength. However, although this technology is expected to improve fatigue strength when processed into a base material, it has the problems of increased base material wear and surface roughness, and new processing technology is required. Multifunction cavitation (MFC) developed in our laboratory is a combined technology that ultrasonic and water jet peening (WJP) and is possible of peening materials in water. In this study, the development and evaluation of the rotating mechanism corresponding to the hourglass-type fatigue test specimen, and the introduction of compressive residual stress and the suppression of surface roughness for the purpose of improving the fatigue strength of SCM420H were investigated. As a result, the developed rotating mechanism was able to process the center part uniformly. In addition, the carburized material of SCM420H was able to apply compressive residual stress while suppressing the surface roughness.