| 摘要 |
PROBLEM TO BE SOLVED: To easily and securely prevent the defective extrusion such as variations in shape and wall thickness, or the torsion in a longitudinal direction from being generated in an aluminum bar material at an initial stage of extrusion or a stage thereafter. SOLUTION: A fitting hole 54 is formed in a insert backer 51 arranged in a bolster 5. An Inconel plate 55, as a metal of low heat-conductivity with a thickness of about 2 cm, is fitted and fixed into the fitting hole 54 so that the plate 55 is brought into contact with a die backer 3 located in the back side of a die 2. The heat conduction and dissipation of the die backer 3, which is heated at a high temperature, to the bolster 5, which is non-heated, is prevented by the high heat-insulation due to the extremely low heat-conductivity and by the air heat-insulating effect due to the surface roughness of a contact face. Thus, the deformation of the die-hole of the die 2 and the defective extrusion caused by the deformation are eliminated. COPYRIGHT: (C)2005,JPO&NCIPI
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