Aluminum Company of America

Other

Hugh C Urmston

Elmer E Pohlenz

A male core designed to be mateable with a female mold for forming vent slots in a thermoplastic closure. The male core comprises a cylindrical member having an end surface which forms an underside top surface and an inside surface of a downwardly depending skirt on the closure. A helical groove is formed about the periphery of the cylindrical member which forms a thread on the inside surface of the skirt. At least one integral rib is formed in the cylindrical member which is arranged parallel to the longitudinal axis of the closure. The rib forms a vent slot in the closure which traverses the thread. Convoluted surfaces are formed on the cylindrical member which extend from each side surface of the rib to the bottom of adjacent helical grooves. The convoluted surfaces provide smooth radii on the ends of the threads adjacent to the vent slot which facilitate axial stripping of the closure from the male core without deforming the threads into the vent slot. This enhances the passage of pressurized gas through the vent slot to the atmosphere as the closure is removed from a container.

Threaded thermoplastic closure with vent slot

Male core for forming vent slots in a thermoplastic closure

An improved method of forming and a construction for a digitally openable container closure. Included therein is a container wall having an inwardly displaceable opening panel defined by a fracturable web which has been formed by selectively displacing metal adjacent a predetermined line substantially perpendicular to the surface of the container wall and by extruding metal between substantially parallel die surfaces which are disposed at an angle to the plane of the container wall. Formed concurrently therewith is an integral inclined deflectable portion projecting outwardly from the container wall adjacent the fracturable web and which deflectable portion is adapted to effect, in response to digitally applied inwardly directed pressure, a relative displacement between the rim of the panel and the lip of the adjacent container wall to selectively strain the web and initiate fracture thereof to permit inward displacement of an opening panel of greater extent than the size of the opening formed in the container wall by the separation of said panel.

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Sparta, NJ, United States of America

Hugh C Urmston