A dynamic small-sized hole flanging process driven by Lorentz-force for aluminum alloys

Lorentz-force-driven (LFD) stamping process is effective in formability enhancement and shape controlling in deep cup drawing. In this paper, LFD process was proposed for small-sized hole-flanging. A series of LFD flanging experiments under different diameters of pre-fabricated hole were carried out, and conventional flanging was implemented for comparison. Defect-free case with smaller prefabricated hole confirmed the potential of the LFD process in reaching higher flanged wall without fracture. Punch velocity captured during experiments reached the maximum value of around 10 m/s for both cases, four defect-free cases and the case of φ = 8.75 mm. A numerical model was established to investigate the deformation behavior and geometrical parameters during LFD flanging. Simulation results showed that excessive radial tensile strain in punch side led to the exceptional increase in thickness strain and thinning at the fillet. In addition, greater effective plastic strain along punch side elements resulted in higher hardening level than that in die side. Furthermore, bending moments would be generated when work-piece contacted with tools fillet, which formed the curved profile in die side and straight profile in flanged wall of punch side. More importantly, edge material attached to punch sidewall when slid through it and the diameter of straight profile there was totally controlled by the punch parameter.