非平底凹模铝板/塑料复合成形中铝板大塑性变形分析

Deformation analysis of heavily strained zones in forming of aluminum sheet via plastics injection molding with mold of non-flat bottom

在注塑机上利用非平底凹模制备了形状较复杂的铝板/聚丙烯复合结构件,实现了将金属板料成形、塑料注射成形融为一体的复合成形的新工艺。利用弹塑性大变形更新的Lagrange有限元法对于复合成形中铝板成形过程进行了数值模拟。成形铝板的实验测试厚度与有限元模拟值具有良好的相符性。铝板成形中形成3个板厚减薄较严重的区域。板厚减薄严重的Ⅱ区,发生了胀形变形和剧烈的塑性剪切变形。Ⅰ区和Ⅳ区之间的大塑性变形区分为B区和C区2个部分,B区内绝对值最大的主塑性应变为负,C区内绝对值最大的主塑性应变为正。Ⅲ区与Ⅳ区之间的D区绝对值最大的主塑性应变为负。

A newly developed approach, in which sheet metal forming and plastics injection molding are integrated, was used to manufacture complex components combined with aluminum sheet and polypropylene with the mold of non-flat bottom via plastics injection molding machine. The updated elastic-plastic Lagrange finite element formulation was used to simulate the forming process of the aluminum sheet. The simulation results agree to the experiment. It is shown that three heavily strained regions were formed in the aluminum sheet. In the most heavily strained region Ⅱ, the deformation is in combination of stretching forming of the sheet and severe plastic shear. The second heavily strained region can be divided into zone B with negative major principal plastic strain and zone C with positive major principal plastic strain. The third largest strained region is in negative major principal plastic strain.