Abstract:

Experiment and numerical simulation are conducted to study the deformation characters and thickness distribution during seamed tube hydroforming to disclose the effect of weld-seam on forming and the generation mechanism of defects. Meanwhile, the comprehensive effect of weld is analyzed in different processes. The results show that the weld-seam is one of the most predilection sites of bursting defects due to the weld plastic drop when bending and leads to wrinkling and bursting in the subsequent process even if the weld-seam is far away from the corner zone. The wall thickness is mainly affected by bending and hydroforming calibration processes. The preforming process has little effect on the thickness. Deformation amount of weld-seam is bigger than that of other zones for its high flow stress, as a result which induces a slight nouniformity thickness distribution. Therefore, the weld-seam is the important factors leading to defects during seamed tube hydroforming. It is helpful to minimize the effects of poor plasticity for weld-seam and prevent bursting defects by placing the weld-seam in the position of slight compressing deformation area.

Key words: bending, seamed tube, weld-seam, hydroforming