Research on deep drawing process with electro-permanent magnetic blank holder for non-ferromagnetic materials.

Through comparing the distribution of blank holder force (BHF) and stress-strain curve along the radial direction, there has been good forming capability and adaptability in deep drawing with the electro-permanent magnetic (EPM) blank holder (EPMBH) technique. However, whether the BHF technique is applicable for non-ferromagnetic materials has yet to be researched. In the paper, taking 08-Al steel and H62 copper plates as examples, the drawability of ferromagnetic and non-ferromagnetic sheets with EPMBH is investigated. Moreover, a series of confirmatory tests were carried out based on numerical analysis. It found that similar to the deep drawing with ferromagnetic slab, there is slight attenuation on the holding effect for non-ferromagnetic sheets, and the effect of gap on the magnetic attraction caused by the magnetic properties of the plate first increases sharply and then slowly decreases, while its possible failure modes are also wrinkling and rupture due to insufficient BHF and excessive drawing height, respectively. In the experiment, flawless deep-drawing workpieces can be obtained with EPMBH, indicating that EPMBH could meet the forming requirement for ferromagnet and non-ferromagnetic plates and can be controllably adjusted through altering the excitation current of the EPMBH device. The experiment result shows that the optimal excitation current is 14 A for ferromagnetic steel plate and 13 A for non-ferromagnetic copper plate with the same diameter of 110 mm and thickness of 0.8 mm. [ABSTRACT FROM AUTHOR]