| 摘要 |
PURPOSE:To make the microstructure uniform after extruding and to increase the yield by heating the tip part and rear end part of an extruding blank higher by the specified temp. than the center part and by extruding the blank by interposing the auxiliary member having the specified heat conductivity in the space with a dummy block. CONSTITUTION:The heating is performed so that the temp. in the zone of respectively 15-100mm in the longitudinal direction from the tip part and rear end part of an extruding material becomes 10-200 deg.C higher temp. than that of the center part of the blank in case of performing a hot extrusion. In case of the extrusion, the following auxiliary member is interposed between the extruding blank and dummy block. Namely the auxiliary member is made of the material having <=0.08cal/cm.sec.deg heat conductivity, having >=1mm thickness. The microstructure at both end parts of the hot extruding material is thus made uniform and the yield is increased without the need for cutting off both end parts. |
