| 摘要 |
PURPOSE:To reduce the vibration amplitude of hunting and to make it possible to bring rapidly the hunting to the end by a method wherein the number of rotation of a pump motor is controlled in such a way that the amt. of sucking and the amt. of evacuation are in accordance with the deviation between a measured value and a set value of the film width and air feeding speed and air evacuating speed are changed. CONSTITUTION:An extruder 2 is actuated and a cylindrical tube (a) extruded from the extruder 2 is passed through pinch rollers 12 from a stabilizing plate 11 and is folded and is guided to a winding machine 15. In addition, a pump 8 is actuated and the film width is adjusted by controlling feeding and evacuation of air to the cylindrical tube (a). For adjusting the film width, the deviation d between a measured value and a set value of the film width is obtd. and the absolute value D0 of the max. deviation the adjustment of which is unnecessary, the absolute value D1 of the estimated max. deviation and the number of rotation R1 of a pump motor corresponding to this D1 are set. When ¦ d¦ >D0, the number of rotation R of the pump motor is controlled in accordance with the equation of R=[R1/(D1-D0)]X(¦ d¦-D0). |
