铝合金管缩口-冲孔复合电磁成形试验研究

Experimental investigation on necking-punching electromagnetic forming for aluminum alloy tube

在薄壁圆管斜壁上进行普通冲孔时,很难做到孔的轴线与斜面完全垂直,且制件表面和冲孔断面质量难以保证。进行了铝合金管缩口-冲孔复合电磁成形试验研究,分析了成形质量和断口形貌。结果表明,磁脉冲缩口-冲孔过程是在高速率变形的惯性和模具复合作用下实现的,高速率缩口变形对冲孔过程起决定作用。在9 kV下实现管端电磁缩口,而在15.5 kV下实现全部冲孔。缩口变形对应的放电参数显著低于缩口-冲孔参数,越靠近缩口变形区端部,冲孔所需放电参数越高。与准静态钢模缩口、软模冲孔相比,电磁缩口-冲孔制件表面质量高,断口塌角高度占原始壁厚40%、毛刺高度约0.05 mm,断面与缩口变形区母线近似垂直。断口内光亮带和剪裂带分界线齐整,剪裂带韧窝密集。

When punch is carried out on the sloping wall of the thin-walled tube,it is difficult to make the axis of punched hole completely perpendicular to the inclined wall,and the surface of part and the punching section are of poor quality. The necking-punching compound electromagnetic forming（EMF） on aluminum alloy tube was studied by experiments,and the forming quality and punching fracture were observed and evaluated. The result shows that the necking-punching compound electromagnetic forming（EMF） process is realized under the compound effect of the inertia from high rate of deformation and die,and the necking deformation under high rate plays decisive role on the punching. Therefore,the tube end necking is realized under the voltage of 9 kV by EMF,and the punching is conducted entirely under the voltage of 15. 5 kV. Furthermore,the discharge voltage for tube end necking is obviously lower than that of necking-punching,and the closer to the outer end of the necking zone is,the higher discharge voltage is for the hole punching. Compared with the quasi static tube end necking with steel die and the punching with soft die,the surface quality of necking-punching part through EMF is higher,the fillet region is 40% of initial thickness of the tube wall,the height of burr is about 0. 05 mm,and the cross section is almost perpendicular to the busbar of necking zone. The boundary between bright zone and the fracture zone is regular,and the dimple is denser in the fracture zone.