基于凸模结构的内筋壳体旋转挤压成形折叠缺陷研究

Research on Folding Defects of Inner Ribbed Shell Based on Punch Structure

针对旋转挤压成形易产生折叠缺陷的问题,利用刚塑性有限元法对镁合金内筋壳体旋转挤压成形过程进行了数值模拟,对比分析了在不同形状的凸模作用下变形区金属流动规律、节点应变和折叠角,探讨了折叠产生的原因.结果表明:折叠缺陷是由于凸模间隙区金属受凸模轴向-周向加载产生凸起,凸起金属受凸模周向加载作用与壳体内侧壁金属汇流;变形区凸起金属轴向流动速度沿径向方向呈递减趋势时无折叠缺陷产生,反之则产生折叠缺陷;增大过度圆角和梯形工作带设计可以避免折叠缺陷产生.

Based on the problem of folding defects produced in rotating extrusion process, the rotating extrusion processing of Mg alloy shell with inner rib was numerically simulated by rigid-plastic finite ele- ment method. The strain of nodes, folding angle and metal flow behaviors were analyzed under different die bearing and the reasons for the folding were discussed. The results show that the folding defect is caused by the embossment produced during axial and circumferential loading of the metal in the gap re- gion of the punch, and the embossment metal circumferential loaded by the punch flow concentration with the metal in the inner side of the shell. The folding defects would not produce with the decrease of the axial flow velocity along the radial direction of the deformation area metal, otherwise there is fold de- fect. Increasing the fillet radius and the design of trapezoidal die bearing can avoid the generation of the fold defects.