To improve the degree of freedom in hole arrangement and formed shape without generating deformation and breakage of a hole and product and movement of the hole by executing forming after in-inserting pins into the holes where the deformation and breakage of the hole shape and movement of the hole shape are generated due to the flow of material in a forming process are generated.
A planar sheet metal 11 on which a number of the holes 12 are punched is prepared and, in the positions equivalent to the holes 12 in corresponding positions in the peripheries of corner parts where the deformation and breakage may be generated at the time of forming this sheet metal 11 by drawing, the pins 14 which are fit into the holes 12 are projected from a forming punch or a pad. When the forming by drawing is executed, first, by inserting the pins 14 into the holes before working and putting the sheet metal 11 between the forming punch and the pad, the flow of material in the corner parts of an article to be formed is suppressed. After that, by executing a usual press working while pressing the outer peripheral part with a blank holder plate, a formed article is formed.
AZUMA KAZUYUKI
YADORI YASUNORI
MINE HIDEO
GOTO TAKAYUKI
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