| 摘要 |
A device for maintaining the width of an extruded blown film 6 and to cool it, the cooled film thereafter being flattened into a double thickness strip, comprising two plates 10 and 12 between which the strip passes with one edge thereof resting on a reference face 14, identical apertures 15 and 16 being provided opposite each other in each plate in the vicinity of the edge of the strip opposite 14, one of said apertures being connected to a pipe feeding compressed air at a predetermined pressure, the other receiving air exhausted from said one aperture, the amount of exhausted air entering the other aperture being dependent upon the degree of masking of the apertures by the edge of the strip, the pressure of air in the exhaust aperture being utilised to control the air supplied to the centre of the die thereby effecting the width of the strip produced by the die. <IMAGE>
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