| 摘要 |
PURPOSE:To control thickness of a multilayer film without utilizing a thickness detector by controlling the extrusion amount of an extruder and drawing velocity or this extrusion amount of the extruder on the basis of the respective extrusion amounts in a plurality of extruders, the width of the molded multilayer film, density of a raw material to be supplied and the thickness target value of the respective layers of the multilayer film. CONSTITUTION:When the lower limit sensor 112 detects the upper face of a raw material 120, the main controlling part 16 of an extruder 116 opens a solenoid valve 114 to start supply of a raw material in a tank 115 thereof to a hopper 117. When the upper limit sensor 111 detects the upper face of the same, the solenoid valve 114 is closed to stop supply of the raw material. The above stages are similarly performed in an extruder 216 side. A cylindrical film 42 overlapped into two layers is blown out from a mold 32 by controlling rotation of the extrusion screws 119, 219 in the extruders 116, 216 and controlling an air pump 33. A winding roller 37 is rotated to draw the film 42 and thereafter winding of a multilayer film 41 is performed by a winding roller 37. |
