| 摘要 |
PURPOSE:To integrally form a spiral projected strip in the extrusion forming direction on the outer peripheral surface by simple mechanism by a method wherein an extrudate, which is extruded from the tip of an extruder and has a projected strip on the outer surface, under softened state is introduced in a sizing die, on the inner surface of which a spiral recessed strip is formed and which has cooling function, so as to be taken up while being rotated in the direction of spiral. CONSTITUTION:An extrudate 4, on the outer surface of which a projected strip 3 is formed, is extruded from the tip 2 of an extruder 1. Said extrudate 4 under softened state is introduced in a sizing die 5 equipped with cooling function. On the inner surface of the sizing die 5, a spiral recessed strip 6 is formed. The extrudate 4 is advanced in the sizing die 5 under the condition that the projected strip 3 of the extrudate 4 is mated with the spiral recessed strip 6. Cooling function is given by circulating cooling water through the hollow part 7 in the interior of the sizing die 5. The extrudate 4 is cooled down while being proceeded under spirally rotating state, which is produced by proceeding the extrudate 4 by mating the projected strip 3 with the recessed strip 6 on the inner surface of the sizing die 5. A take-up unit 9 takes up the extrudate 4 while rotating in the direction indication with the arrow 10 in synchronization with the rotation of the extrudate 4. |
