Abstract: An apparatus includes an upper lip positioned with respect to an air flow passage. The upper lip is to direct air flow from the air flow passage around a bubble of blown film. The apparatus further includes a Venturi ring movably mounted with respect to the upper lip and adjustable in position with respect to the upper lip. The Venturi ring is to adjustably lock the bubble of blown film.

Abstract: A pressure chamber is provided for a blown film extrusion apparatus having (i) a die head for extruding a tubular polymer bubble, and (ii) a cooling assembly down-stream of the die head for receiving the bubble and applying a cooling fluid to the bubble. The pressure chamber includes an upstream end wall sealed around the die head outlet, and extending outward from the seal; a side wall movable between a closed position for controlling air flow from a chamber volume surrounding the bubble to the atmosphere, and an open position for permitting air flow from the chamber volume to the atmosphere. The upstream end wall has an inlet for receiving air from an air supply, and an outlet in fluid communication with the inlet and configured to direct the air into the chamber volume to pressurize the chamber volume when the side wall is in the closed position.

Abstract: An apparatus is used in the continuous extrusion of blown films which includes a die suitable for use in forming a blown film bubble, and one or more primary gas outlets for use in stretching and drawing the extruded film prior to it stabilizing. The primary gas outlets direct cooling gas streams on the interior and/or exterior surface of an unstabilized portion of the blown film bubble as it emerges from the die. Secondary cooling gas outlets are also provided to introduce secondary gas streams into an upper stabilized portion of the blown film bubble above the bubble frost line. An exhaust conduit in gaseous communication with an interior of the bubble is used to maintain the gas pressure in the blown film bubble interior at a desired pressure. The exhaust inlet is located at a position adjacent the bubble frost line spaced away from the primary cooling gas outlets and marginally towards the secondary gas outlet.