| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide extrusion dies for forming a hollow material, allowing high-speed extrusion, and capable of lengthening the service life by preventing rupture of a mandrel, even when extrusion-molding a billet made of a high-strength alloy requiring a large extruding force, particularly, a high-strength aluminum alloy such as the so-called 7000 system. <P>SOLUTION: This extrusion dies 10 include a male die 20 for molding an inside shape of the material by extruding the billet B sent from the upstream side to the downstream side, and a female die 30 for molding an outside shape of the material. The male die 20 is constituted of the mandrel 22 and a holder 25 for holding its outer periphery. The mandrel 22 is formed of a material interior-forming part 23, and a bridge part 24 for supporting the material interior forming part 23 and having a tip outer peripheral surface mutually engaging with an inner peripheral part of the holder 25. An engagement surface between the tip outer peripheral surface of the bridge part 24 and the inner peripheral part of the holder 25, is formed as an inclined face which approaches the die center toward the downstream in the extrusion direction. <P>COPYRIGHT: (C)2012,JPO&INPIT |
