起动发电机弹性轴断裂分析

针对起动发电机发生的弹性轴断裂故障，通过采用对断裂弹性轴进行宏微观观察、金相组织分析、硬度检测等方法，综合分析判断该发电机弹性轴断裂性质为扭转疲劳断裂失效，弹性轴锥体与转子空心轴之间配合不良是弹性轴发生扭转疲劳断裂的根本原因。进一步研究发现:起动发电机弹性轴采用锥面贴合的方式来传递扭矩，而在实际制造及修理过程中锥面贴合度难以保证，导致工艺可控性差、产品可靠性偏低，存在结构设计不合理的问题。提出将弹性轴锥体结构改成花键结构的建议，以避免故障再次发生。

Fracture Analysis of Flexible Shaft of Starter Generator

The flexible shaft of a starter generator fractured during service. In order to find out the failure mode and cause, macro and micro observation, metallurgical structure analysis, and hardness testing were carried out. It is found that the failure mode of the flexible shaft is torsion fatigue. The main fracture cause of the shaft is the mismatching between the flexible shaft and the rotor hollow transmission shaft. The flexible shaft transmitted the torque by means of conical surface joint. However, it is hard to reliably guarantee the conical surface joint proportion during the production and maintenance processes, leading to poor process controllability and low reliability of products, as well as the problem of unproper structure design. The suggestion that the flexible shaft should change the conical structure to spline structure was proposed to prevent such failures.