随车吊机销轴断裂原因

Reasons for the fracture of the pin shaft of the truck mounted crane

某随车吊机机械臂与液压杆的连接处销轴在运行过程中突然发生断裂事故。采用宏观观察、化学成分分析、金相检验、硬度测试、扫描电镜及能谱分析等方法分析了销轴断裂的原因。结果表明:在运行过程中,销轴外表面应力集中处萌生裂纹,裂纹沿淬硬层周向向两边快速扩展,最终汇合导致表面一周开裂;在交变载荷的作用下,周向裂纹沿作用力方向扩展,形成双源疲劳开裂;当销轴剩余有效强度不足时,销轴发生一次性快速断裂。

The pin shaft at the connection between the mechanical arm and the hydraulic rod of a truck mounted crane suddenly broke during operation.The causes of pin fracture were analyzed using methods such as macroscopic observation,chemical composition analysis,metallographic examination,hardness testing,scanning electron microscopy and energy spectrum analysis.The results show that during operation,cracks initiated at the stress concentration point on the outer surface of the pin shaft,and the cracks rapidly propagated along the circumferential direction of the hardened layer to both sides,eventually converged to form cracks around the surface.Under alternating loads,circumferential cracks propagated along the direction of the applied force,formed dual source fatigue cracking.When the remaining effective strength of the pin shaft was insufficient,the pin shaft experienced a one-time rapid fracture.