变压边力对拼焊板焊缝移动和成形性能的影响

焊缝两侧材料变形不均匀和由此引起的焊缝移动是拼焊板成形过程中需要解决的难题。应用动力显式数值模拟软件，研究了线性渐增和渐减变压边力下拼焊板盒形件的成形过程。建立了线性变压边力终止值随初始值变化的关系曲线，该曲线被拟合为二阶多项式曲线。模拟结果表明，线性渐增变压边力允许更多厚侧材料流入凹模，从而减少焊缝移动量；线性渐减变压边力较定常压边力显著增加了厚侧材料的变形程度，提高了焊缝两侧材料变形的均匀性。

Weld-bead Migration and Formability of Tailor Welded Blank Based on Variable Blank Holding Force

Uneven deformation and related weld-bead migration are the important problems that needs to be solved during tailor welded blanks(TWBs)forming.The forming of box with TWBs based on a series of linearly increasing and decreasing variable blank holding forces(VBHF)over the stroke were studied by means of dynamic explicit finite element method.The terminative value of the linear VBHF trajectory decreased with the initial value increasing.Consequently the relation curve between the initial and terminative values was obtained,which can be fitted by a second-order polynomial.The numerical simulation results demonstrate that the linearly increasing and linear decreasing VBHF have different effects on TWBs forming.The linearly increasing VBHF is beneficial to the thicker blank side drawn in more easily whilst the thinner blank side is stretched more,so that the weld-bead migration is reduced obviously.Compared with the constant BHF,the linearly decreasing VBHF allows more deformation for the thicker blank side,distributes the deformation uniformly and thereby improves TWBs formability.