发动机托架后安装板翻边成形拐角区域的开裂研究

Study on cracking in corner area of flanging for rear mounting plate of engine bracket

从调整首次拉延圆角、增设工艺凸包和增加工艺切口圆角3个方面,利用Autoform有限元分析软件,研究了发动机托架后安装板成形质量的变化规律。分析了首次拉延圆角r_(0)与二次拉延圆角r_(1)的比值对缺陷和料厚的影响规律,随着首次拉延圆角r_(0)值的增加,最终成形工件的料厚呈现先增加再减小的趋势,越靠近r_(0)=0.75r_(1)(即k=0.75),材厚越大。当r_(0)=r_(1)时,增设工艺凸包对破裂缺陷具有一定的改善作用;当r_(0)=0.75r_(1)时,增设工艺凸包对缺陷和料厚的改善作用很小。随着工艺切口圆角r_(切口)的增大,能够有效减小应力集中系数,FLD中对应于原始破裂位置的点已完全进入安全区域,且距离成形极限曲线越来越远,料厚呈现增大趋势,对缺陷的改善效果明显。

From three aspects of adjusting the first drawing fillet,adding process convex and process cut fillet,the changing law of forming quality for rear mounting plate of engine bracket was studied by finite element analysis software Autoform,and the influence laws of the ratio of the first drawing fillet r_(0)and the secondary drawing fillet r_(1)on the defects and material thicknesses were analyzed.Then,with the increasing of the first drawing fillet r_(0),the material thickness of final formed workpiece first increased and then decreased,and the closer to r_(0)=0.75r_(1)(i.e.k=0.75)is,the thicker the material is.The results show that when r_(0)=r_(1),adding process convex can improve the fracture defect to a certain extent,and when r_(0)=0.75r_(1),adding process convex has little effect on improving defects and material thickness.Furthermore,with the increasing of process cut fillet r_(切口),the stress concentration factor is effectively reduced,the point corresponding to the original fracture position in FLD completely enters the safe area and gets farther and farther from the forming limit curve,the material thickness shows an increasing trend,and the defect improvement effect is obvious.