Hydro-forming of tailor-welded blanks

Due to the requirements to save the energy and to reduce the tail gas in automobile, making good use of forming technologies in the tailor-welded blanks (TWBs) which can reduce the part weights significantly becomes more and more important. And, nowadays Hydro-forming techniques have been largely accepted by industries for the production of components characterized by complex shape, good surface quality and small residual stress. Unfortunately, for the hydro-forming TWBs of difference in thickness, there are many problems such as weld movement, thickness and uneven strain distribution which restrict the hydro-forming further application of TWBs. This paper investigates the hydro-forming process such as deep drawing with mutative pressure onto the blank, different friction conditions and hydraulic pressures in the cavity. Studies show that the amount of weld movement reduces with the hydraulic pressure in the cavity rises and the max value is 0.27mm. Meanwhile, a comparison between hydro-forming technologies and conventional deep drawing indicates that the maximum strain displaces not in bottom but in limbic weld line of workpieces. And little tread of thinning out TWBs in thickness, more homogeneous strain distribution, less weld movement and better formability with certain friction conditions are typical for hydro-forming technologies compared to conventional deep drawing.