In this study, the effect of a wedge on a piercing punch on hole-expansion ratio has been investigated. As a result, the holes pierced using a wedged piercing punch showed significantly high hole-expansion ratios under certain conditions. Regarding the wedge vertical angles, the hole-expansion ratio becomes high at 80 degrees and low at 45 degrees. The sheet bending effect caused by the wedge shape contributes to these results. The small amount of bending in the case of 80 degrees induces tensile stress around the punch edge without plastic deformation, which accelerates material fracture. This acceleration decreases plastic strain on the pierced surface and leads to the high hole-expansion ratio. On the other hand, a large amount of bending in the case of 45 degrees causes plastic deformation around the punch edge, which deteriorates the hole-expansion ratio. Regarding the material direction when set on a die face, the hole-expansion ratio becomes high when the material direction at which the stretch-flange formability is the highest is at 90 degrees to the wedge tip line. In this condition, the stretch-flange formability at the weakest position resulting from piercing using the wedged punch becomes the highest in the other material directions.
