关键词: 板材成形, 拉深成形, 电控永磁, 压边力控制, 磁路设计

Abstract:  In order to overcome the problems that the conventional blank holder could not apply BHF independently, and the overheating problem of electromagnetic blank holders, a novel blank holder technique was proposed based on EPM technology.  According to the characteristics of EPM technology and deep drawing processes, a deep drawing die with magnetic cushion was designed and manufactured. The magnetization and demagnetization states of magnetic pole unit and the cushion were simulated by finite element analysis(FEA). Based on the coupling analysis of magnetic field and mechanics field, the distributions of contact pressures applied on the sheets by magnetic forces were determined. By using FEA, the deep drawing processes of cylindrical cups were simulated with conventional blank holder and the new technique respectively. The results show that the strain distributions of the drawn parts obtained by the two blank holder methods is basically the same. Using EPM blank holder, the drawing experiments of 08Al sheets (thickness is as 0.98 mm) with diameters of 180 mm and 195 mm were carried out, where the drawing heights were as 48 mm. The results demonstrate that the large enough BHF may be applied independently using the new EPM blank holder method. Finally, the energy consumption of the conventional blank holder, the electromagnetic blank holder and the EPM blank holder method were calculated respectively. Among them, the EPM blank holder method has the best energy saving effectiveness. Compared with the electromagnetic blank holder, the energy saving rate using the new blank holder method is as high as 95%.

Key words: sheet metal forming, deep drawing, electro-permanent magnet(EPM), blank holder force(BHF) control, magnetic circuit design