PREVENTING METHOD FOR SURFACE DEFECT OF METALLIC ARTICLE FORMED BY SPLIT DIE

摘要

PURPOSE:To prevent the intrusion of a metal into the flash line of a split die and to prevent the formation of streak defect, by setting a hollow crude article at one of two split dies having raised pattern and having directions of different angles, by pressing a mandrel having segmental circle-shaped section to conduct primary formation, then by conducting formation by use of another die. CONSTITUTION:A crude article is set in the first split die of upper and under dies 7a, 7b where the first split die and the second split die, which have the same recesses for forming a raised pattern and which have directions 90 deg. different from each other, are arranged. Then a mandrel 6 having a diameter larger than that of the crude article and having a segmental circle-shaped section is pressed into the first split die in order to conduct primary formation. Subsequently, the primary form is set in the second split die which is arranged at an angle of 90 deg. to the first split die, and the second formation is conducted by the segmental circle-shaped mandrel 6, thereby manufacturing a formed product 1.