| 摘要 |
PURPOSE:To permit the regulation of the position of an electrode to the optimum position whereat a good sheet molding condition can be obtained in a short period of time, by a method wherein the variations of thickness in the direction of the flow of a resin sheet and the widthwise direction of the same are detected by a detecting means while the variation is separated into the components of variation of a thickness in a plural frequency areas by an analyzing means. CONSTITUTION:Molten resin is extruded through a die 1 to obtain a sheet 2 while static electric charge is impressed on the sheet in a space until the sheet arrives at a cooling roll 3 by the electric bulb 4 of a needle type electrode, in which a multitude of needles is arranged. A detecting means 9 is a device for measuring the thickness of the sheet by the absorption of infrared rays of a thermoplastic resin and measures the fluctuation with time of the thickness of the sheet at positions near both ends in the widthwise direction of the sheet and at the center of the same while the measured values are separated into the frequency area of 0.5-2Hz and the same area of 10-30Hz to operate respective components of fluctuation by an analyzing means 10 and set the optimum distance between the electrode and the resin sheet. The position of electrode rays is regulated based on the variation of the thickness of 'components of undulation', further, the variation of thickness of the component of striping is also controlled by means 5, 6 to minimize it. |
