| 摘要 |
PURPOSE:To fine a recrystallized organization of a surface part of an extrusion shape, and to prevent the generation of a crack of the shape in the course of working by providing a refrigerant passage for cooling a bearing surface in the periphery of an extrusion aperture in a die, and providing a refrigerant passage on a die ring. CONSTITUTION:Refrigerant passages 7, 8 for cooling bearing surfaces are provided in the periphery of an extrusion aperture 5 in a die 2, and a refrigerant passage 16 for making the refrigerant passages 7, 8 communicate with a refrigerant supply pipe 19 for supplying a refrigerant to these passages 7, 8 is provided on a die ring 4. At the time of an extrusion working, when the refrigerant is fed into the refrigerant passages 7, 8 through the refrigerant passage 16 from the refrigerant supply pipe 19, the bearing surface of the extrusion opening 5 is cooled by the refrigerant passing through the inside of the refrigerant passages 7, 8. Accordingly, a temperature of the bearing surface is made roughly uniform with a temperature of other part of the die 2, and a recrystallized organization of the surface part of the extrusion shape is fined.
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