Importance

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Abstract

A press-forming die (1) includes a die (2) having a die corner (21), which follows along an inward-facing corner (41) of a blank sheet (4), and a punch (3) having a punch corner (31). A corner groove (6) extends along a portion of the punch corner at which leading surfaces (33) and a side surface (34) intersect in a relative stroke direction (X) of the punch. The corner groove is shaped such that its groove width (W) decreases in the stroke direction and converges at a punch corner center (C1). A shoulder radius (Rps) of punch shoulders (3S), which are portions along which the corner groove and the leading surfaces intersect with the side surface, a sheet thickness (t) of the blank sheet (4), and a flange length (Ls) at both ends of the inward-facing corner preferably satisfy the relationship t≦Rps≦Ls.

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First Claim