摘要
The influence of the size of pre-cut hole of blank on the formability of cylindrical hole flanging in single point incremental forming（SPIF） was studied. The flange is produced in four stages starting from 45° to 90° and employing aluminum as the test material. It is shown that the hole size has significant effects on the stress/strain distribution on the cylindrical flange. The magnitude of hoop strains increases and the flange thickness increases as the hole size increases. Likewise, the von Mises stress reduces with the increasing of hole size. Further, there is a threshold value of hole size（i.e., 80 mm） below which severe stresses occur, which lead to sheet fracturing thus failing the successful forming of cylindrical flange. Moreover, the formability reduces as the hole size is increased above the threshold size. Finally, it is concluded that 80 mm is the threshold size of hole for maximizing the formability of aluminum sheet in incremental hole flanging.
研究单点渐进成形中坯料预切孔尺寸对圆柱孔翻边的可成形性的影响。翻边制造从45°到90°分为4个阶段,采用铝作为实验材料。孔尺寸对圆柱翻边的应力/应变分布有显著影响。随着孔尺寸的增大周向应变增大,翻边的壁厚增厚。同样地,随着孔尺寸的增大von Mises应力降低。而且,孔尺寸存在一个临界值(80 mm),当低于这个值时会产生严重的应力,从而导致板材断裂,圆柱翻边成形失败。随着孔尺寸的减小,且大于临界尺寸时,可成形性降低。结果表明,孔的临界尺寸为80 mm能使铝板在渐进孔成形中的可成形性能最大化。
