挤出机摩擦离合器螺栓断裂分析

Fracture Analysis on Bolts of Friction Clutch for Extruder

某挤出机中气动摩擦离合器与减速器端连接的螺栓在使用过程中经常发生断裂,改用另一种材料的螺栓后情况未有很好改善。采用化学成分分析、力学性能测试、断口分析和金相检验等方法,对螺栓断裂的原因进行了分析。结果表明:起裂源位于螺栓的加工刀痕、表面擦伤处及因微动疲劳所致的螺纹微裂纹处,这些部位均存在应力集中,在振动作用下,萌生的裂纹不断扩展,使有效承载面积不断减小,最终引起螺栓疲劳断裂。

The connecting bolts between pneumatic friction clutch and reducer for extruder fractured frequently in the process of using. Switch to another material of bolt, but it not showed considerable improvement. By means of chemical composition analysis, mechanical property testing, fracture analysis, metallographic examination and so on, the fracture reason of bolt were analyzed. The results showed that the cracks originated at tool marks, surface scratches and microcrack caused by fretting fatigue, where was the stress concentration position. And the cracks extended under the vibration, which reduced the effective bearing area; at last the fatigue fracture occurred in bolts.