切角板坯对纯铜薄板矩形盒拉深影响的试验及数值分析

Experiment and numerical analysis of blank shape's effect on pure copper sheet metal rectangular case drawing

在大量纯铜薄板矩形盒拉深试验的基础上,结合有限元计算,分析了矩形盒的拉深特性。指出,矩形切角板坯使法兰曲边变形分布得以改善,非拉深变形抵抗弱化,提高了拉深成形性。有限元模拟结果显示矩形板坯拉深断裂点产生在凸模肩部转角附近,且始终承受两向不等拉伸,应变计算值与实际拉深测定值相符;切角板坯的拉深断裂点则转移至接近凹模口的侧壁处,且始终处于压剪组合变形状态,断裂时板厚应变相当小,认为倾向于剪切断裂。切角板坯断裂点的拉、压应力组合效应使该点板厚几乎不变,是提高拉深极限的重要因素之一。

On the basis of a large volume of pure copper sheet metal rectangular case drawing experiments combining finite element computation,this paper analyzed drawing characteristic of rectangular case.It is pointed out that the sheared rectangular blank ameliorates deformation distribution of flange curve side and weakens the non-deformation resistance,which is good for improving forming of rectangular case.The results of finite element simulation show that the breakpoints of rectangular blank take place nearby the corner of punch shoulder and endure by-direction stretch.Strain computation values match the actual measured ones.The breakpoints of sheared blank shift to side wall of die and are in press-shear combination situation;because blank thickness strain is rather small when fracturing,it is considered as shear fracture.That stretch-press stress combination on the breakpoint of sheared blank make the thickness of this point remains almost unchanged is one of the important factors improving the drawing limit.