EXTRUDING DIE FOR FORMING HOLLOW SECTION

PROBLEM TO BE SOLVED: To provide an extruding die for forming a hollow section, attaining a long service life by preventing the breakage of a spider while attaining high-speed extrusion even when extrusion-molding a billet made of a high-strength alloy with high extrusion working force, particularly a so-called 7,000 series highest-strength aluminum alloy.SOLUTION: The extruding die 10 includes a male die 20 for molding the inside shape of the hollow section by extruding the billet B downstream from the upstream side, and a female die 30 for holding the male die 20 and molding the outside shape of the hollow section. The male die 20 includes the spider 22, and a holder 25 for holding the spider 22. The spider 22 is formed of a mandrel 23, and a plurality of bridge parts 24 supporting the mandrel 23 and allowing tip outer peripheral surfaces 24C to engage with a bridge holding surface 25C. The tip outer peripheral surface 24C of each bridge part 24 and the bridge holding surface 25C of the holder 25 are joined by shrinkage fitting.