影响闭挤式精冲成形表面质量的因素分析

首先分析了成形面撕裂与变形区应力状态的关系，然后用塑性有限元数值仿真和物理实验的方法，分析了材料塑性、凸凹模间隙、外环填充率、反顶力对成形表面质量的影响。研究表明：主、副凹模闭合时，变形区材料所受的压应力越大，所得精冲件成形面质量越好；材料塑性越好，剪切面撕裂带宽度越小；凸、凹模间隙越大，工件轮廓面光亮带的比例越小；材料剪切面光亮带比例随着外环填充率的增加而增加；随着反顶力的增加，工件轮廓面光亮带的比例明显增大。研究成果为闭挤式精冲新工艺的应用奠定了基础。

Analysis of factors affecting formed surface quality of closed extruding fine blanking

The relation between the tear of forming face and the stress state in the deformation zone was analysed, and the effects of the material plasticity, the clearance between punch and die, the filling rate of outer ring and the counterforce on the quality of formed surface were analyzed by means of the plastic finite element numerical simulation and the physical experiments. The results show that when the main and vice dies are closed, the greater the compressive stress in the deformation zone material, the better the quality of the stamping parts; the better the plasticity of the material, the smaller the width of the tearing band of the shear plane; the greater clearance between punch and die, the smaller the proportion of the bright surface of the workpiece; the percentage of bright band of material shear surface increases with the increase of the filling rate of outer ring; with the increase of counterforce, the proportion of bright band of workpiece contour surface gets increased obviously. The results laid a foundation for the application of closed extruding fine blanking process.