抽水蓄能电站巴氏合金上导轴瓦损坏原因分析

由于冷却油供油路中出油不均匀,使得油槽中存在大量漩涡或空气,造成轴瓦上半部分的油膜无法形成或形成不均匀,从而在运行过程中产生了油膜压力波动。同时,由于轴瓦轴向摆动的灵活性较差,轴瓦上半部分与滑转子间隙较小,轴瓦只有上半部分与滑转子接触,致使轴瓦表面单位面积受力过大。上述两种原因造成的瓦面上半部分应力幅值增加,使轴瓦产生了疲劳破坏。为此,利用光学显微镜和直读光谱仪对轴瓦巴氏合金的组织和成分进行了分析,在此基础上,提出了适宜的改进措施。实践表明,轴瓦金相组织中再无区域性偏析、聚集和组织分层现象出现,Cu6Sn5分布均匀,Sn Sb未发生区域性偏析,组织形貌与两种硬相Sn Sb和Cu6Sn5的总量符合要求。通过对轴瓦衬垫结构进行改进,使得轴瓦摆动的灵活性加大,轴瓦和滑转子之间形成了稳定的油膜,从而使轴瓦受力均匀,运行平稳。

Failure analysis of upper guide bush of babbitt Alloy for pumped storage station

In the maintenance check of a pumped storage station, due to uneven cooling oil supply of oil pipe, many vortexes or air were existed in the oil tank, which caused uneven and failed oil film formation at the upper part of bush, leading to oil film pressure fluctuation during operation process. At the same time, due to the poor swing flexibility of bush in axial direction, the clearance between upper part of bush and the axis is small, causing large local surface stress on the area of bush. For the two above causes, fatigue damage of babbitt alloy bush occurred. The metallurgical structure and chemical composition of babbitt alloy bush were analyzed by using optical microscope and directly reading spectrometer. It was found that there were no regional segregation, aggregation and delamination defects for metallurgical structure of the babbitt alloy bush, and the distribution of Cu6Sn5 was uniform without regional segregation of SnSb, so the microstructure and total amount of the 2 kinds of hard phase all met the requirements. Based on the analysis results, the improved measures were studied and put forward, namely increasing the swing flexibility of upper bush, so as to help forming a stable oil film in the contact area of upper bush and axis, thus the bush had an even stress distribution and stable operation.