Apparatus for automatic control of cage size in an extruded film production line
OwnerDaniel R. Josephinventor
Life of this patent
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Abstract
A system and controller for positioning an adjustable sizing cage for use with a blown film extrusion apparatus. A cage sizing subsystem is used to position the cage relative to the film tube. At least two non-contact sensors arranged on the sizing cage to provide signals to an automatic controller, which in turn positions the sizing cage a predetermined distance from the extruded tube. Two different modes of operation are provided for the controller when the size of the tube is to be changed: a forecast mode in which relatively large cage movements of the cage are made, and a contact mode in which the cage is maintained either in contact with the extruded tube, or at an operator selected distance from the extruded tube.
Claims23
An apparatus for positioning an adjustable sizing cage in a blown film extrusion apparatus in which film is extruded as a tube from an annular die and then pulled along a predetermined path and located within the adjustable sizing cage, the apparatus comprising:
- a supply blower which supplies air to said extruded film tube in an amount corresponding to a supply control signal;
- an exhaust blower which exhausts air from said extruded film tube in an amount corresponding to an exhaust control signal;
- a controller member including executable program instructions which define at least one control routine for automatic and coordinated control of said at least one of the exhaust or supply blowers during extrusion of said extruded film tube by directing a series of supply control signals to said supply blower and/or exhaust control signals to said exhaust blower;
- a sizing cage subsystem surrounding said extruded film tube and including an electrically actuable and controllable actuator configured for moving said sizing cage inward and outward relative to said extruded film tube;
- at least one first non-contact sensor for measuring a distance between said cage subsystem and said extruded tube;
- at least one additional non-contact sensor for measuring a diameter of said extruded tube;
- and
- wherein said executable program instructions include a cage position control routine which utilizes said sizing cage subsystem-to-tube distance to control a location of said sizing cage subsystem when moving said sizing cage subsystem from a first position to a second position during startup and resizing of said extruded film tube.
An apparatus for positioning an adjustable sizing cage in a blown film extrusion apparatus in which film is extruded as a tube from an annular die and then pulled along a predetermined path and located within the adjustable sizing cage, the apparatus comprising:
- an airflow control system for controlling the quantity of air in the tube, the system including:
- a supply blower which supplies air to the extruded film tube in an amount corresponding to a supply control signal,
- an exhaust blower which exhausts air from the extruded film tube in an amount corresponding to an exhaust control signal;
- a sizing cage subsystem surrounding the extruded film tube and including an actuator configured for moving the sizing cage inward and outward relative to the extruded film tube;
- a plurality of sensors configured and arranged to measure a distance between the cage subsystem and the extruded tube and configured to measure a diameter of the extruded tube;
- and
- a cage position controller configured to move the sizing cage inward or outward relative to the extruded film tube during extrusion of the tube, responsive to the measurements made by the sensors.
Dependencies are inferred from the claim text.