| 摘要 |
A device for automatically controlling and correcting the size of film produced by what is generally designated as the "bubble" process. The device basically comprises a flow block plate valve mechanism which blocks, partially blocks, or permits free flow of air into the bubble responsive to the movement of opposed film edge followers sensing film width deviations. The edge followers operate without the need for a fixed reference point, and by employing pneumatic means whereby contact and bruising of the film edges by such followers is avoided.
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