54 / 2021-03-26 21:43:01

动车组牵引电机连接器冠簧损坏机理研究 Study on Damage Mechanism of Crown Spring for EMU Traction Motor’s Connector

Traction Motor’s Connector牵引电机连接器,Crown Spring 冠簧,Failure Analysis 失效分析,Adhesive Wear 粘着磨损,Arc Erosion 电弧侵蚀

       A certain type of Harmony EMU traction motor connector was repaired after running 4.8 million kilometers, and a small number of connector terminals were found to have obvious melting or surface burns. The male terminal contacts the inner crown spring of the female terminal directly. Poor contact during the service process will cause heat accumulation, which will cause the traction power of the EMU to be lost. It will have a great impact on the safe and stable operation of the EMU. Therefore, in order to reveal the cause of the connector joint melting and increase the life of the traction motor joint, it is necessary to grasp the mechanism of the damage of the crown spring due to service vibration and evaluate the damage degree, and provide theoretical guidance for the subsequent reduction of its failure rate to ensure the safe service of the EMU.

       In this paper, the surface damage morphology analysis, composition analysis and chemical state analysis, three-dimensional profile analysis and mechanical performance test of the crown spring after service have been systematically analyzed and studied. The analysis results show that there are obvious arc erosion and adhesive wear in the damaged area. The arc erosion of the reed with less damage is more obvious, and the silver coating is basically not missing. On the other hand, the surface of the reed with more damage has more adhesive wear and oxidation marks, and the silver coating has completely disappeared. Not only that, the severely damaged reed has more pronounced depressions, and its surface hardness, tensile strength, fracture strength, and yield strength show upward trends. However, due to the serious damage on the surface, the cross-sectional elongation has decreased compared with other reeds. According to the above analysis, the failure of the crown spring is the result of both mechanical and electrical wear. And the closeness of the crown spring in contact with the connector terminals and the accumulation of temperature are important reasons to accelerate its failure.

       某型和谐号动车组牵引电机连接器服役480万公里后进行检修时，发现少量连接器接头公母端子存在明显的烧熔或表面灼伤；而公端子与母端子内冠簧直接接触，在服役过程中其接触不良将会引起发热累积，从而导致动车组牵引动力丢失，对动车组的安全稳定运行产生很大影响。因此，为了揭示连接器接头烧熔原因，提高牵引电机接头寿命，需掌握冠簧因服役振动产生的损伤的机理并评估其损伤程度，为后续降低其故障率，确保动车组的安全服役提供理论指导。

       本文研究针对服役后冠簧开展了表面损伤形貌分析（SEM)、成分分析（EPMA）及化学状态分析（XPS）、三维轮廓分析和力学性能测试等系统分析和研究。分析结果显示损伤区域均存在明显的电弧侵蚀和磨损现象，损伤程度较轻的弹片电弧侵蚀更为明显，银镀层基本没有出现缺失，而程度较重的弹片表面粘着磨损痕迹与氧化程度更严重，银镀层已完全消失；不仅如此，损伤严重的弹片的表面硬度、抗拉强度、断裂强度与屈服强度反而呈现上升趋势，但由于其表面损伤严重，断面延伸率相比其他弹片有所下降。通过上述分析，冠簧的失效是机械磨损与电气磨损共同导致的结果，冠簧与连接器端子接触的紧密程度以及温度的积累是加速其失效的重要原因。