5182铝合金椭圆孔电磁翻边数值模拟研究

Numerical Simulation Study on Oblique Hole-Flanging with 5182 Aluminum Alloy Produced by Electromagnetic Forming(EMF)

目的研究异形孔电磁翻边成形规律及不同预制孔尺寸对翻边质量的影响。方法基于电磁成形平台实现椭圆孔电磁翻边试验,建立三维电磁成形仿真模型对3种预制孔的翻边过程进行模拟。通过显微硬度值、翻边轮廓、翻边高度及端部厚度等指标分析异形孔电磁翻边规律。结果3种预制孔的翻边高度均表现为从长轴到短轴不断增大,随着预置高度从15 mm降到10 mm,长短轴两处的翻边高度差由2 mm下降至0.75 mm,且翻边零件与模具贴合效果逐渐变好。结论电磁翻边件在长、短轴处的变形存在着明显差异;基于中性层不变原理的预制孔公式,在侧壁与模具贴合良好的案例中低估了电磁翻边高度;变形区域内较为均匀的电磁力密度分布有益于实现与模具良好贴合,同时翻边高度更加均匀。

This paper aims to study the mechanism of oblique hole flanging conducted by electromagnetic forming(EMF)and the effect of prefabricated hole on flanging quality.Experimental works based on the EMF platform and 3D numerical model were carried out to simulate the electromagnetic flanging processof three kinds of prefabricated holes.The rule of elec-tromagnetic flanging of special shaped hole was analyzed by microhardness value,flanging contour,flanging height and end thickness.The results show that flanging heights of all three types of prefabricated holes exhibitincreasing from the long axis to the short axis,and the difference in flap height between the long and short axis decreases from 2 mm to 0.75 mm as the preset height decreases from 15 mm to 10 mm and the fit of the flap parts to the mold gradually becomes better.There are obvious dif-ferences in the deformation of electromagnetic flanging parts in the long and short axis.Based on the principle of neutral layer invariance,the formula of prefabricated hole underestimates the electromagnetic flanging height when the side wall fits well with the mold.Better die gap fitness and uniform flanging height could be achieved by more uniform magnetic force density generated in deforming region.