To provide a film tension detector capable of reducing periodical maintenance works and precisely detecting the tension of a film, provide a film tension control device capable of controlling the tension of the film based on the tension of the film detected by the film tension detector and preventing meandering and slack of the film, and provide a bag-making packaging machine provided therewith.
When the tension of the film is changed, a dancer roller 12 moves to upper/lower positions of a reference position and a pantograph mechanism 60 extends/contracts interlocked therewith. A spring 30 is extended/ contracted with the extension/contraction of the pantograph mechanism 60. A strain amount of a load cell 31 connected to the spring 30 is changed and the load cell 31 outputs a detection signal S according to the strain amount to the control device. CPU of the control device calculates the displacement of the load cell 31 from the reference position based on the detection signal S outputted from the load cell 31, and the rotation speed of a motor is controlled based on the displacement so as to fixedly hold the tension of the film.
MIYAMOTO HIDESHI
ICHIKAWA MAKOTO
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