抄録
For carburized gears, shot-peening method is widely used for improvement bending fatigue strength. But, the effect of shot-peening on tooth surface strength of carburized gears has not been clarified due to its complicated mechanism. In this study, the author investigated the influence of the shot-peening on surface strength of roller using a disk machine with rolling and sliding. Fatigue tests were carried out with carburized SCM420 steel rollers whose two type conditions of shot-peened rollers; ultrasonic shot-peening and air shot-peening. As a result of experiments, the shot-peening deteriorates surface strength of roller; in particular deterioration of surface strength of air shot-peened roller is remarkable. Former failure patterns like pitting or spalling does not observed. In this experiment, mainly observed failures were micro pitting. Shot-peening causes increasing of surface roughness, then lubricated condition became boundary lubrication. Most cracks were generated from contact surface. During operating, asperities of surface roughness were directly contacted, then cracks were generated and propagated and it became micro pitting.
