A Fundamental Study on the Surface Durability of Medium-Hardness Gears. (3rd Report, The Meaning to give Difference of Hardness between a pair of gears).

Abstract

The effects of the combination of tooth flank hardness and tooth surface roughness on the surface durability of medium-hardness gears are examined by using a disk machine. The meaning to give difference of hardness between a pair of gears is investigated. In the case that the surface roughness is different between the contact surfaces with same initial hardness, the severe wear and pitting occur on the smooth surface. Because the tip of asperities on the rough surface hardens strongly due to the repetition of contact. Therefore it is necessary that the initial hardness of smooth surface is higher than that of rough one in the combination of different surface roughness. This means that the combination of hardness between a pair of pinion and gear should be determined by considering the condition of tooth surface finishing.