| 摘要 |
PURPOSE:To prepare speedily and stably a hollow undrawn body with which ultradrawing can be done at high speed, by molding the hollow undrawn body while it is cooled from both the outer and inner faces. CONSTITUTION:A double die 3 is constituted of an inner die 11 having a hole 10 for supplying a cooling medium, covered with an insulating material in the center, an outer die 13 being set at an interval of a circular ring shaped gap 12 outside it, an indirect cooling part 4 being set adjoining to an end of said outer die 13 and a direct cooling part 15 being set adjoining in the forwarding direction of an undrawn body. Polyoxymethylene supplied from a hopper 1 is melted and plasticized in an extruder 2 and is introduced into the indirect cooling part 4 without being exposed to air through the heated double die 3, and the undrawn body is prepared while being cooled from both the outer and inner faces of the undrawn body. The hollow undrawn body 6 which has come out of the indirect cooling part 4 is completely solidified in the direct cooling tank 5 where a cooling medium such as water is filled, and thereafter it is taken up by means of a taking-up device 7 and finally wound on a winding device 9 through a guide 8. |
