To provide an extrusion die for a metallic hollow material which can reduce production cost and maintenance cost, has no restrictions on the cross-sectional shape in the hollow part of a hollow material, hardly causes cracks and chippings in a mandrel, and has excellent workability.
In the extrusion die in which a female die 3 is fitted into the annular base part 20 of a male die 2, and a mandrel 1A having many forming projecting parts 10 is held so as to be inserted into a mandrel holding hole 27 at the center of the bridge part 21 of the annular base part 20. The mandrel 1A is composed of a main body piece 11 having a U-shaped holding frame part 13 opened in an extrusion direction side and a tip piece 12 provided with the many forming projecting parts 10, and the tip piece is fitted into the holding frame part 13 so that it cannot be pulled out.
Ken Takada
Kurose Yasuhisa
Yoshihito Shimizu
Toshiya Kido