鼠笼式电机转子钎焊模卡导条拉脱原因分析及解决措施

Cause Analysis and Solution Measure of Bars Pulling from Brazing Joints of Squirrel Cage Motor Rotor Brazing Simulation Sample

某型机车牵引电机鼠笼式转子端环与导条模卡钎焊外观检查合格后进行拉伸试验,部分端环-导条钎焊接头的导条从焊缝位置拉脱,不能满足抗拉强度要求。为解决该问题,通过渗透探伤和宏观检测发现端环内侧与导条的钎缝界面存在微裂纹、钎料填充不致密和分层等缺欠。端环-导条结构设计不合理以及钎焊高温持续时间不足是导致拉脱问题的主要因素。针对这两个因素提出了改进方案:端环槽深由6 mm改为4 mm、增加端环槽内侧45°倒角,冬季钎焊时450℃保温时间延长为90 s。改进后经拉伸试验验证,成功解决了导条拉脱的问题,保障了产品质量。

Tensile test are conducted after the brazing VT for end ring and bar joints of squirrel cage rotor of a certain type of traction motor.It is found that part of the bar is pulled off from the end ring and bar joint beam,this result cannot satisfy the tensile strength requirement.In order to solve this problem,micro-cracks,undense filler metal filling and delamination were found in the brazing interface between the inner side of the end ring and the conductor bar through penetration testing and macroscopic testing.It is pointed out that the unreasonable design of end-ring and conductor bar structure and the insufficient duration of high temperature brazing are the main factors leading to the pull-out problem.In view of these two factors,the improvement scheme is put forward:the depth of the end ring groove is changed from 6 mm to 4 mm,the inner chamfer of the end ring groove is increased by 45°,and the holding time of 450℃is extended to 90 s in winter brazing.After the improvement,the tensile test proved that the problem of pulling out of the conductor bar was solved successfully and the product quality was guaranteed..