Shot Peening Of The Gear Surface With Ground Cracks

Author:  Y. Tan, B. Ma, L. Ren, Q. Ye
Source:  Conf Proc: ICSP-3, (p.247-252)
Doc ID:  1987084
Year of Publication:  1987
Abstract:  
Tiny cracks always occur on the ground surfaces of case hardened machine particularly for carburized gear with abusive grinding. Most of cracks are within the depths from 0.05mm to 0.15mm. According to the statistical data for locomotive driving gears in a factory there were 5-10% products which were suffered from tiny cracks on the teeth parallel to the gear profiles. In general case the cracked ones should be treated as waste products thus it will cause economical loss. In order to ensure the safety of cracked gears in operation, by some means or other to put the gears into use will be a valuable research work. If the surface of gear contour was undergone shot peening, it would form a surface strengthened layer. The depth of this layer is about 0.2-0.4mm. Compressive residual stress was induced in the layer. If the depths of ground crack is shallow, the front of crack does not cross over the compressive stress area that the cyclic contact stress can not lead to early surface spalling. The gear with ground cracks has the same ability to resist contact fatigue stress as the normal gear. Experiments and analyses were made systematcially on the locomotive driving gears so that we can confirm the rationality about the use of gears with ground cracks.