PURPOSE: To unify the structure of a thick part 101 and thin part 102, to eliminate the strength difference between them and hence restrain the generation of bend after stretching by making both of them to be the double fiber structure of 100] and 111].
CONSTITUTION: An aluminum material to be extruded is simultaneously extruded from the two forming holes 2, 2 and three discharging holes 3, 3, 3 by advancing a stem. The thick part 101 of the extruded material which is passed through the forming hole 21 is turned into the double fiber structure of 100] and 111]. On the other hand, a part of the material to be extruded which is concentrated in the vicinity of the forming hole 22 for thin part is extruded through the discharging hole 3. Thus, the metal flow which is passed through the forming hole 22 for thin part is affected by the discharging hole 3, turned into an approximate state to a metal flow which is passed through the forming hole 21 for thick part and the thin part 102 of extruded material also is turned into the double fiber construction of 100] and 111].
TANIGAWA MASAKAZU
DOUSAKA KOUZOU
