机车电机转轴及小齿轮轴断裂失效分析

Fracture Failure Analysis for Traction Motor Rotation Shaft and Pinion Shaft of Locomotive

为查明某机车电机转轴以及与之过盈配合的小齿轮轴的断裂原因,对断口形貌、化学成分、硬度和显微组织进行了综合分析。结果表明:转轴及小齿轮轴的断裂均为旋转弯曲微动疲劳断裂;断裂原因主要是由于转轴与小齿轮轴过盈配合面的微动磨损以及小齿轮轴的油槽与油孔交界处的应力集中,应力集中导致疲劳裂纹的萌生,然后在旋转弯曲应力的作用下扩展直至断裂,小齿轮轴的起裂及断裂均先于转轴。

Fracture morphology, chemical composition, hardness and microstrueture were analyzed to find the fracture reason of traction motor rotation shaft and pinion shaft of a locomotive which were interference fit. The results showed that the rotation shaft and pinion shaft were all rotation bending fretting fatigue fracture, the main reasons of fracture were the fretting abrasion of the interference surface between rotation shaft and pinion shaft and stress concentration on the junction of the pinion shaft;s oil groove and hole, fatigue cracks initiated because of the stress concentration, and then extended under the action of rotation bending stress to fracture finally. The crack initiation and fracture of pinion shaft were earlier than those of rotation shaft_