Abstract: An air ring has a main body including a plenum through which pressurized air enters the air ring, the main body including a generally circular interior that is unobstructed vertically above the main body. A generally circular forming-cone assembly is received in the generally circular interior of the main body, and includes at least one annular lip defining a passage through which pressurized air from the plenum exits the air ring for impingement upon the polymer tube. A plurality of fasteners secure the forming-cone assembly in the interior of the main body, the fasteners and forming-cone assembly being unobstructed vertically above the air ring, wherein the fasteners are accessible from vertically above the air ring and the forming-cone assembly is removable from the main body by vertical lifting without removal of other components from the air ring.

Abstract: An air ring has a main body including a plenum through which pressurized air enters the air ring, the main body including a generally circular interior that is unobstructed vertically above the main body. A generally circular forming-cone assembly is received in the generally circular interior of the main body, and includes at least one annular lip defining a passage through which pressurized air from the plenum exits the air ring for impingement upon the polymer tube. A plurality of fasteners secure the forming-cone assembly in the interior of the main body, the fasteners and forming-cone assembly being unobstructed vertically above the air ring, wherein the fasteners are accessible from vertically above the air ring and the forming-cone assembly is removable from the main body by vertical lifting without removal of other components from the air ring.

Abstract: A method comprises the steps of continuously measuring, proximal a tube extrusion die, a diameter of tubing extruded by the die, to produce a plurality of die-measurement or layflat samples; and continuously measuring, downstream of the tube extrusion die and proximal an accumulation point of flattened tubing, a width of the flattened tubing, to produce a plurality of flat-width samples. A slope value is calculated over a selected interval of the layflat samples and the flat-width samples to determine the stability of the diameter of the tubing and the width of the flattened tubing. A y-intercept value is calculated over the selected interval of the layflat samples and the flat-width samples to determine a forecast trend of the diameter of the tubing and the width of the flattened tubing.

Abstract: A method comprises the steps of continuously measuring, proximal a tube extrusion die, a diameter of tubing extruded by the die, to produce a plurality of die-measurement or layflat samples; and continuously measuring, downstream of the tube extrusion die and proximal an accumulation point of flattened tubing, a width of the flattened tubing, to produce a plurality of flat-width samples. A slope value is calculated over a selected interval of the layflat samples and the flat-width samples to determine the stability of the diameter of the tubing and the width of the flattened tubing. A y-intercept value is calculated over the selected interval of the layflat samples and the flat-width samples to determine a forecast trend of the diameter of the tubing and the width of the flattened tubing.

Abstract: The present invention relates to a method of automatically calibrating a valve in a fluid flow path of a blown-film extrusion apparatus. The calibration process detects and measures a first and second pressure drop in the flow characteristic, as well as the valve position and time. The process further detects time required to achieve a steady-state in the flow characteristics. These measurements are recorded and used in calculating appropriate valve positions.

Abstract: The present invention relates to a method of automatically calibrating a valve in a fluid flow path of a blown-film extrusion apparatus. The calibration process detects and measures a first and second pressure drop in the flow characteristic, as well as the valve position and time. The process further detects time required to achieve a steady-state in the flow characteristics. These measurements are recorded and used in calculating appropriate valve positions.

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.

Abstract: An apparatus for producing an extruded film tube and supplying said tube to a collapsing and roller assembly includes a die for extruding a molten material in the form of a tube which is in a molten state below a frost line and in a solid state above the frost line. A blower system supplies and exhausts cooling air to and from an interior portion of the tube, and is regulated by a valve. At least two sensors are provided, one below the frost line for sensing the position of said tube, and one located proximate the tube in a position above said frost line. The upper sensor is used for sensing the position of the tube prior to collapsing and flattening it. A controller receives feedback signals from both sensors and controls operation of the valve.

Abstract: An apparatus for producing an extruded film tube and supplying said tube to a collapsing and roller assembly includes a die for extruding a molten material in the form of a tube which is in a molten state below a frost line and in a solid state above the frost line. A blower system supplies and exhausts cooling air to and from an interior portion of the tube, and is regulated by a valve. At least two sensors are provided, one below the frost line for sensing the position of said tube, and one located proximate the tube in a position above said frost line. The upper sensor is used for sensing the position of the tube prior to collapsing and flattening it. A controller receives feedback signals from both sensors and controls operation of the valve.

Abstract: An apparatus for producing an extruded film tube and supplying said tube to a collapsing and roller assembly includes a die for extruding a molten material in the form of a tube which is in a molten state below a frost line and in a solid state above the frost line. A blower system supplies and exhausts cooling air to and from an interior portion of the tube, and is regulated by a valve. At least two sensors are provided, one below the frost line for sensing the position of said tube, and one located proximate the tube in a position above said frost line. The upper sensor is used for sensing the position of the tube prior to collapsing and flattening it. A controller receives feedback signals from both sensors and controls operation of the valve.

Abstract: An improved blown film extrusion apparatus is provided. The apparatus includes an annular die for extruding a film tube. At least one tube position transducer is provided and located adjacent to the extruded film tube. The tube position transducer transmits interrogating pulses to the extruded film tube and produces a position signal corresponding to a detected position under the extruded film tube. A bubble position control system is provided for receiving and processing the position signal. A valve is provided for varying a quantity of air within the extruded film tube in response to the bubble position control means. This urges the extruded film tube to a desired position. The apparatus further includes a collapsing frame assembly for receiving the extruded film tube and collapsing it. The collapsing frame assembly includes several frame boards. Typically, two opposing main boards and two opposing side boards are provided.

Abstract: The present invention is directed to a method and apparatus for startup of extruded film tubes. A controller member is utilized to provide control signals to a supply blower which supplies air to the extruded film tube in an amount corresponding to a supply control signal, and an exhaust blower which exhausts air from the extruded film tube in an amount corresponding to an exhaust control signal. The controller member executes program instructions which define at least one control routine for automatic and coordinated control of the supply blower and the exhaust blower during starting of the extruded film tube, by directing a series of supply control signals to the supply blower and exhaust control signals to the exhaust blower.

Abstract: A blown film extrusion apparatus and method is provided including a tube position transducer transmits interrogating pulses to the extruded film tube and produces a position signal corresponding to a detected position under the extruded film tube. A bubble position control system is provided for receiving and processing the position signal. The apparatus further includes a collapsing frame assembly for receiving the extruded film tube and collapsing it. A position transducer is provided for detecting the position of at least one of the frame boards. At least one board position actuator is provided for adjusting the position of at least one of the boards. A board control system is provided for receiving the board position information from the board position transducer and for providing control signals to the board position actuator to maintain at least one of the boards in a predetermined position.

Abstract: A system for starting up an extruded film tube in a blown film extrusion apparatus includes a subsystem for varying a quantity of air in the extruded film and a subsystem for executing program instructions which control the operation of the subsystem for varying a quantity of air. The subsystem for varying a quantity of air in the extruded film tube includes a supply blower and an exhaust blower. The program instructions include at least one routine for the automatic and coordinated control of the subsystem for varying a quantity of air in the extruded film tube.

Abstract: An apparatus for producing an extruded film tube and supplying said tube to a collapsing and roller assembly includes a die for extruding a molten material in the form of a tube which is in a molten state below a frost line and in a solid state above the frost line. A blower system supplies and exhausts cooling air to and from an interior portion of the tube, and is regulated by a valve. At least two sensors are provided, one below the frost line for sensing the position of said tube, and one located proximate the tube in a position above said frost line. The upper sensor is used for sensing the position of the tube prior to collapsing and flattening it. A controller receives feedback signals from both sensors and controls operation of the valve.

Abstract: The present invention is directed to an apparatus for startup of extruded film tubes. A controller member is utilized to provide control signals to a supply blower which supplies air to the extruded film tube in an amount corresponding to a supply control signal, and an exhaust blower which exhausts air from the extruded film tube in an amount corresponding to an exhaust control signal. The controller member executes program instructions which define at least one control routine for automatic and coordinated control of the supply blower and the exhaust blower during starting of the extruded film tube, by directing a series of supply control signals to the supply blower and exhaust control signals to the exhaust blower. When a valve is utilized to control the flow of air from the supply blower to the extruded film tube, the controller is also utilized to adjust the supply blower and the exhaust blower in order to optimize operation of the valve by placing the valve in a substantially linear operating range.

Abstract: The present invention is directed to a blown film extrusion apparatus in 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 system for gauging and controlling the surface of the extruded film tube, which includes a number of components which cooperate together. At least one transducer is provided and positioned adjacent the extruded film tube for transmitting interrogating pulses to, and receiving interrogating pulses from, the extruded film tube, and for producing a signal corresponding to a detected position of the extruded film tube. A control system is provided for substituting a filtered position signal derived from a dynamic filtering process in lieu of the detected position signal. An air flow controller is provided for varying a quantity of air within the extruded film tube in response to the control system for urging the extruded film tube to a desired position.

Abstract: A method and apparatus for blown film extrusion is described. An annular die receives a molten material and extrudes a film tube. At least one cooling ring is positioned adjacent the annular die for passing an air stream along a particular surface of the film tube. A blower entrains and supplies air to the cooling ring. A flow sensor is positioned in an air flow path intermediate the at least one cooling ring and the blower. It provides a mass air flow signal which is a measure of air mass flow per unit time. An adjustable air flow attribute modifier is placed in communication with the air flow path and operates to selectively modify the air mass flow per time unit. A controller member is in communication with the flow sensor and the adjustable air flow attribute modifier, for receiving the mass air flow signal and for controlling the adjustable air flow attribute modifier to provide a preselected value of air flow in terms of air mass flow per unit time.

Abstract: In a blown 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 extruded film tube for transmitting and receiving interrogating pulses along paths normal to the extruded film tube, and for producing a current position signal corresponding to the circumference of the extruded film tube. The current position signal is continuously compared with at least one previous position signal, preferably with a computer program resident in a controller memory. If at least one preselected condition is violated, the current position signal is disregarded in favor of an estimated position signal.

Abstract: 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 extruded film tube for transmitting and receiving interrogating pulses along paths normal to the extruded film tube, and for producing a current position signal corresponding to the circumference of the extruded film tube. The current position signal is continuously compared with at least one previous position signal, preferably with a computer program resident in a controller memory. If at least one preselected condition is violated, the current position signal is disregarded in favor of an estimated position signal.