通过对某自升式平台齿轮齿条升降系统的失效齿轮及全新齿条分别进行化学成分分析、金相检验和硬度测试, 分析了造成该系统中齿轮失效的原因。结果表明: 齿轮的失效形式为接触疲劳失效; 齿轮材料表面热处理不均匀, 节圆附近无硬化层, 导致其失效面的表面硬度低于与其相啮合齿条的表面硬度,这是造成该齿轮长期服役后在节圆附近发生接触疲劳失效的主要原因。

Component analysis, metallographic examination and hardness test were performed respectively for a disabled pinion and a brand-new rack of the jacking system of a jack-up platform. The results show that because the superficial heat treatment of the pinion was not uniform, there was no hardened layer near the pitch circle of the pinion. Thus the surface hardness of the disabled pinion was lower than that of the rack, which led to the contact fatigue failure of the pinion near the pitch circle.