Control of tubular film size
AssigneeGloucester Engineering Co., Inc.
InventorsRonald D. Cluett, Richard L. Mitchell
Life of this patent
Estimating the term…
Abstract
An internally cooled blown film system, for producing a plastic tube, in which the flow rate of the continuous flow of cooling air through the tube is made directly dependent upon deviation of the tube circumference as determined by transmission and detection of ultrasonic waves from the surface of the tube.
Claims17
In a film extruder system in which film is extruded as a tube from an annular die and then pulled along a predetermined path, an apparatus for gauging and controlling the circumference of said extruded-film tube comprising
- one or more ultrasonic-ranging-transducer means spaced around the exterior of said tube and oriented so as to transmit and receive sonic pulses along paths generally normal to the surface of the tube,
- means for energizing each said transducer to transmit a sonic pulse to and receive a return pulse from the surface of said tube,
- means associated with each transducer for generating a range signal representative of the time required for said pulse to travel to and from said tube, and
- means responsive to said range signals for varying the quantity of air within said tube for controlling the tube diameter.
In a film extruder system in which film is extruded as a tube from an annular die and then pulled along a predetermined path, a method for gauging and controlling the circumference of said extruded-film tube comprising the steps of
- disposing one or more ultrasonic-ranging-transducer means around the exterior of said tube and orienting them so as to transmit and receive sonic pulses along paths generally normal to the surface of the tube,
- performing a measurement cycle in which each said transducer transmits a sonic pulse to and receives a return pulse from the surface of said tube,
- generating a range signal representative of the time required for said pulse to travel to and from said tube, and
- varying the quantity of air within said tube in response to said range signals in order to control the tube diameter.
Dependencies are inferred from the claim text.