铝合金管坯电液成形试验研究

Experimental investigation on electrohydraulic forming of aluminum alloy tube

电液成形是利用水中高压脉冲放电产生的冲击波使坯料发生高速率变形的塑性加工方法。基于柱面凹模进行5A02铝合金管坯电液成形试验,分析电压和金属丝直径对变形的影响;针对一步成形圆角变形区难以贴模现象,进行两步胀形试验。研究结果表明,变形量随放电电压升高而增大,在给定放电电压条件下,存在一个临界金属丝直径对应成形效果最佳,而临界金属丝直径随放电电压提高而增大。管坯变形总体上处于双向拉伸应变状态,其中变形区中间为近平面应变状态,靠近圆角区为近双等拉应变状态。相对于一步成形,在圆角区,两步电液成形接近完全贴模,壁厚分布相对均匀。

Electrohydraulic forming（ EHF） is a high-rate plastic deformation technology,which makes the sheet metal to form at a high speed by the shockwave generated from high voltage discharge under water. The experimental investigation on EHF of aluminum alloy5A02 tube was performed by the cylindrical die,and the influences of discharge voltage and wire diameter on EHF were analyzed. Furthermore,the experiments of two-step EHF process were explored to avoid inadequate deformation in the corner by one-step process. The results show that the deformation increases with the rise of high voltage,and there is a critical wire diameter corresponding to the maximum deformation under a constant discharge voltage. The critical wire diameter increases with the rise of voltage. The deformed tube is in a biaxial tension strain state after EHF. However,the middle of deformation zone reaches a plane strain state,and the region near the inner corner of the deformation zone is close to a biaxial equal tension strain state. In contrast to the filleted corner caused by one-step EHF process,the one by two-step is in the almost full attaching-die condition and the thickness of deformed tube wall is relatively uniform.