| 摘要 |
PURPOSE: To reduce a variation in the width direction of a sheet and enhance a strength by a method wherein just after a ring sheet is extruded, cooling gas having a temperature lower than that of the ring sheet is blown against the surface of the ring sheet to cool the ring sheet, and the cooling gas is sucked and evacuated through a path along an extruder die forming a ring slit. CONSTITUTION: An expanded sheet Pe is extruded in a balloon form out of a ring slit 14 of an extruder die member 10. Meanwhile, pressurized cooling air having a temperature lower than that of the expanded sheet Pe is supplied from a cooling air supply opening 75. Just after the expanded sheet Pe is extruded, the pressurized cooling air is blown against the outer surface of the expanded sheet Pe through a ring path 73. A part of the pressurized cooling air is forcibly sucked from a cooling air suction opening 45 by a suction pump through ring paths 70 and 71. At the same time, pressurized cooling air is supplied also to a nozzle 30 forming an inner sheet surface cooling device through a first pipe 21. The pressurized cooling air is blown against the inner surface of the expanded sheet through a ring path 32, thereafter being continuously sucked through a second pipe 22. |
