某快递物流公司的带式输送机用滚筒轴在运转时经常发生断裂，严重影响物流线的正常运行。通过宏观分析、金相检验、扫描电镜断口分析、化学成分分析以及受力分析等方法，对滚筒轴断裂原因进行了分析。结果表明：由于滚筒轴未进行调质处理，降低了材料的强度和疲劳性能；轴表面在加工时留下粗糙刀痕，成为疲劳裂纹源；滚筒轴轴径变化处的过渡圆角半径偏小，造成该处应力集中严重；滚筒轴在工作中处于不停的运转中，极易在轴肩角应力比较集中的位置发生疲劳断裂。最后提出了相应的改进措施。

The belt conveyor roller shafts of a logistics company often fractured in the operation, which seriously affected the normal operation of the logistics line. Through macroscopic analysis, metallographic examination, SEM fracture analysis, chemical composition analysis and force analysis, the fracture reasons of the roller shaft were analyzed. The results show that the strength and fatigue properties of material of the roller shaft were reduced due to no quenching and tempering treatment. The rough machining marks on the shaft's surface became the source of fatigue cracks. The fillet radius of the roller shaft diameter changing position was too small and caused the stress concentration. The roller shaft was in continuous operation, so fatigue fracture easily happened at the stress concentrated shaft shoulder. Finally, the corresponding improvement measures were put forward.