| 摘要 |
The present invention is directed to a blown film extrusion apparatus i n which film is extruded as a tube from an annular die and then pulled along a predetermined path. The improved blown film extrusion apparatus includes a means for gauging and controlling the surface of the extruded film tube, whi ch includes a number of components which cooperate together. At least one transducer means is provided and positioned adjacent the extruded film tube for transmitting interrogating pulses to, and receiving interrogating pulses fro m, the extruded film tube, and for producing a signal corresponding to a detected position of the extruded film tube. A control means is provided for substituting a filtered position signal derived from a dynamic filtering process in lieu of the detected position signal. A means is provided for varying a quantity of air within th e extruded film tube in response to the control means for urging the extruded film tube to a desired position.
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