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Flanging U-shaped piece is the typical auto-body part, such as tailor-welded front rail inner panel, whereas, large springback amount is a critical challenge in sheet metal forming process, which size and shape accuracy affect the quality of the following assembly process. Firstly, a new form of variable blank holder force (BHF) was proposed in this paper, the springback problem was analyzed by numerical method based on the constant BHF of 90 t, and the contours of Von-Mises stress and springback amount were calculated by the dieless method. Secondly, variable BHF with changes in position and punch stroke was designed and used to control springback. Finally, orthogonal experimental and range analysis method were used to optimize the variable BHF parameters. In addition, the springback angles of sidewall and flange under 16 different combinations were calculated.