| 摘要 |
PURPOSE:To eliminate the uneven sheet-thickness by a method wherein the waveform and phase of voltage output, which is applied by a high-voltage generator to a moving cooling body, are variably controlled in synchronization with the change of the thickness of a produced sheet. CONSTITUTION:A polymeric sheet 2, which is melt-extruded from a mouth piece 1, is cooled and solidified by being brought into contact with a moving cooling body 3. The surface of the cooling roller 3 is held at high potential by being applied with high voltage generated by a high-voltage generator 5. In addition, the change of the thickness of the sheet in contact with the roller is monitored with a thickness measuring apparatus 6. Obtained thickness change waveform signal is sent to a waveform signal analyzer 7 so as to be analyzed in order to express the signal in terms of the sum of a plurality of sinusoidal waves. Control signals generating potential change to apply periodic waveforms, the frequencies and amplitudes of which are equal to and the phases of which are shifted at 180 degrees to each of split up sinusoidal waves, are sent from the analyzer 7 to the high-voltage generator 5 in order to variably control the surface potential of the cooling roller 3 as mentioned above. |
