A novel process of deep drawing based on electro-permanent magnet combined segmental blank holder technique

A new electro-permanent magnet combined blank holder technique has been developed by using permanent magnetic force to supply the blank holding force (BHF) for sheet metal deep drawing. In this work, the workability of the designed magnetic circuits was simulated and tested. A series of numerical simulations and experiments have also demonstrated its ability to overcome temperature rise and provide sufficient magnetic force. The advantages and availability of the combined blank holder technique were expatiated by theoretical derivation, and analyzed by FE stress analysis. The feasibility and effectiveness of the new blank holder method have been proven by a series of experiments for deep drawing a workpiece of 08Al with a diameter of 220 mm. With the segmental blank holder, the flange wrinkling is demonstrated to be suppressed well than using the single blank holder. Also, experimental results corroborated that current is only instantaneously imposed when switching magnetic force state, and not at other times.