汽车转向节凹模失效分析与寿命研究

Failure Analysis on Female Die for Knuckle and Its Service Life

分析了转向节闭式锻造典型失效模具的断口形貌、模具结构及化学成分,同时研究了模具工作应力状态与表层温度分布对其失效形式的影响。结果表明:模具结构及制坯形状设计不合理,造成失稳和引起应力集中是模具早期失效的主要原因;磨削加工对模具的表面质量有很大的影响,模具表面强烈的局部过热而造成表面烧伤、硬度下降和很高的表面拉应力,引发磨削裂纹,从而严重降低摸具的疲劳强度和断裂抗力,造成模具失效。

The fracture appearance, the configuration and chemical composition of the failure dies were analyzed, and the influence of stress distribution and layer temperature on the failure dies were researched too. The results show that the main reasons of early failure of the female die are the unsteady and the stress concentration, which are caused by the unreasonable die structure and blank form. And the attrition machining has an extremely important influence on the surface quality. The increment of local surface layer temperature in the die will causes surface burning, hardness descending and higher surface pull stress arising, which will result in the aUrition flaw and reduce the fatigue strength seriously and cause a failure of the die.