| 摘要 |
PURPOSE:To keep the film tension almost constant and perform a good heat- sealing, by providing a controller regulating the revolution numbers of a relief motor in accordance with the transferred distance of a transferable dancer roll corresponding to the tensile strength of a film provided in a film guide. CONSTITUTION:A film guide 13 is provided to guide a film F to return back it between a film feeder 1 and a film folding back part 5. And a transferable dancer roll 20 according to the tensile strength of the film F is equipped in this film guide 13. And the number of revolution of the relief motor 3 to wind off the film roll R is controlled to increase or decrease by a controller 22 in accordance with the transferred distance of the dancer roll 20. For instance, when a swing arm 19 is shifted a little upward from a substantially horizontal position, the number of revolution of the relief motor 3 is regulated to decrease, but when the swing arm 19 is shifted a little downward from the substantially horizontal position, the number of revolution of the relief motor 3 is regulated to be faster. In this way, the swing arm 19 is corrected to keep almost horizontal and also to keep the tensile strength almost constant. And hence, the tensile strength of the film F can be kept appropriate during heat-seal by the subsequent sealing parts 8, 10 to perform a good heat-sealing.
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