EXTRUSION DIE FOR FORMING HOLLOW MATERIAL

摘要

[Problem] To provide an extrusion die for forming a hollow material in which extrusion can be performed at high speeds, spider breakage is prevented, and service life is increased, even when extruding a billet comprising a high-extrusion-force, high-strength alloy, and particular a 7000-series maximum strength aluminum alloy. [Solution] An extrusion die (10) is provided with a male die (20) through which a billet (B) is extruded from an upstream side to a downstream side and, the male die adapted for forming an inside shape of a hollow material; and a female die (30) for holding the male die (20) and forming an outside shape of the hollow material. The male die (20) is formed of a 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) for supporting the mandrel (23), and enabling a distal-end outer peripheral surface (24C) to engage with a bridge-holding surface (25C). The distal-end outer peripheral surface (24C) of each of the bridge parts (24) and the bridge-holding surface (25C) of the holder (25) are joined by shrink-fitting.