Abstract: The tube hydroforming process for manufacturing the tubular part with large perimeter difference was studied by means of experiments and FE simulation. It is an asymmetrical one and the expansion ratio is 70 percent. The part is successfully hydroformed by applying the useful wrinkles to accumulate sufficient metal in the area with large expansion ratio. The thickness distribution is analyzed, and the maximum thinning ratio of the part is 21.6 percent. It is shown from the experiment and simulation results that the tubular part with large perimeter difference, long expansion area and asymmetrical shape can be obtained in one step, applying the useful wrinkles. Typical failure modes were analyzed.

Key words: Hydroforming, Large expansion, Useful wrinkle, Asymmetrical part