In a blow film extrusion system in which film is extruded as a tube from an annular die and then pulled along a predetermined path, an apparatus is provided for gauging and controlling the circumference of the extruded film tube. At least one transducer, preferably ultrasonic, is mounted adjacent the...http://www.google.es/patents/US5104593?utm_source=gb-gplus-sharePatente US5104593 - Method and apparatus for gauging and controlling circumference of extrusion-blown film
Method and apparatus for gauging and controlling circumference of extrusion ...
