To extrude an extruded material having stable and appropriate size and shape in the longitudinal direction by forming an air layer for heat insulation between a die and a die ring.
This extrusion tool 1, is supported by a die slide 11 of an extrusion machine together with a bolster 9 and a dummy bolster, and at the time of executing the extrusion, the die ring 3 is gradually cooled during extruding, and it is restrained to conduct the heat held in the outer peripheral part side of the die 2 in the radial line direction to the die ring 3 side by the air layer 6 for heat insulation between the die 2 and the die ring 3. Therefore, the die 2 is held at almost the fixed stable temp. in the radial line direction during extruding to produce the extruded material E having stable and appropriate size and shape in the longitudinal direction. Further, since grooves 7 forming the heat insulating air layer 6 are formed in the inner peripheral surface of the die ring 3 having general applicability, the number of the extrusion tool constitutional members can be reduced.
TATSUMOTO SHINYA
SUDO MASAMI
