Effect of Shot Peening on Tooth Surface Properties and Tooth Surface Strength of Carburized Gears.

Abstract

Clear results about the effect of shot peening on tooth surface strength of carburized gears have not been clarified. The author carried out experiments to study the effect of shot peening on tooth surface strength using test gears whose tooth surfaces were finished by grinding, where eight conditions of shot peening were processed. It was shown that the application of some peening conditions increased the tooth surface strength, while the application of other peening conditions decreased the tooth surface strength compared to that of not-peening. Furthermore, the variations in the tooth surface properties, i.e. residual stress, hardness, surface roughness and tooth profile after shot peening were observed and discussed in relation to the tooth surface strength. As a result of experiments, tooth surface strength is improved by the shot peening under the condition which integral value of residual compressive stress and mean value of hardness near the surface are higher. In addition, it was found that tooth surface strength becomes low when the gears are peened by the shot condition which keeps the tooth surface from running-in since shot peening affects the running-in of tooth surface.