The effect of asperity interaction on scoring in the rolling-sliding contact of two rollers. 4th report The effect of surface roughness in the case of carburized rollers.

Abstract

Using a two-disk machine, the process leading up to the occurrence of scoring on carburized rollers having four different surface roughnesses was investigated in detail, under four different conditions of asperity interaction brought about by two combinations of the direction of lay of high-speed-roller/low-speed-roller (circumferential/circumferential or axial/axial) and two drive ratios of the rollers (integral 2 or hunting 1.95). The state of oil film-formation, which was related to the film parameter, was better in pairs of rollers with axial lay than in pairs or rollers with circumferential lay. For smaller initial surface roughness, the coefficient of friction and the surface temperature are also smaller. The effect of surface roughness on the scoring limits could be predicted from these tribological features. But in the case of the hunting drive ratio, the experimental results on the scoring limits were scattered. This can be attributed to the variations in the local severities of asperity contacts at each revolution. And in the cases where the surface roughness was very small the scoring limits did not increase so much because of local concentrations of contact stresses at the side ends of the roller.