Method and apparatus for forming a notched hinge connection in a thermoformed container
AssigneeTekni-Plex, Inc.
InventorsBabu Kuruvilla, Richard L. Ramirez, Mark A. Bergeron
Life of this patent
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Abstract
Method and apparatus for forming a hinge in a thermoformed container, such as an egg carton, and the resulting container. The hinge is formed in the mold, by severing a thermoformed container along the length of a hinge line, with the exception of plurality of spaced connecting membranes that are not severed. The alternating severed portions and connecting membranes are referred to herein as a notched hinge connection. The width, depth, and location of the connecting membranes can be adjusted so the hinge area is strong enough to withstand multiple openings during use.
Claims16
A method of thermoforming a hinged plastic container comprising:
- thermoforming a hinged container from a sheet of thermoformable material in a mold, the mold including a top molding surface having:
- a first molding surface for forming a first portion of the container;
- a second molding surface for forming a second portion of the container;
- and
- a hinge molding surface between the first and second molding surfaces for forming a flat planar hinge connection area between the first and second portions of the container;
- providing a knife positioned above the hinge molding surface, the knife having a cutting blade movable against the hinge molding surface;
- clamping the flat planar hinge connection area against the hinge molding surface;
- cutting a notched hinge line in the clamped hinge connection area of the thermoformed container in the mold, the notched hinge line including severed portions separated by connecting membranes joining the adjacent portions of the container, and wherein the hinge molding surface has a plurality notches, spaced apart along the hinge line, in which the connecting membrane portions are formed.
A method of forming a tri-fold plastic thermoformed egg carton comprising:
- providing a unitary sheet of plastic material suitable for thermoforming;
- thermoforming the sheet to form a cell base, a cell cover and a lid, the thermoformed sheet including a hinge connection between adjoining edges of the cell base and the cell cover for pivoting of the cover and base between open and closed positions, the base and cover each having a complimentary matrix of cells that together form a matrix of cell pockets for holding individual eggs when the cover is in the closed position over the base, the lid and base having a hinge connection between opposing edges for pivoting between open and closed positions, wherein when the cover and base are in the closed position the lid can be closed over the cover to form an assembled carton;
- the hinge connection between the cell base and cell cover including a common planar wall portion having an upper planar surface lying in a common plane CP, a plurality of thermoformed connecting membranes recessed from the CP and spaced apart along a hinge axis of the hinge connection;
- forming a severed hinge line severing the common planar wall portion without severing the connecting membranes, such that the connecting membranes form a hinged connection between the severed portions of the common planar wall portions, and wherein the hinge connection is formed by thermoforming the sheet against a notched striker bar, the notched striker bar having a planar wall with a plurality of spaced apart grooves, wherein the connecting membranes are formed by deforming the sheet into the grooves of the notched striker bar to form the connecting membranes, and a continuous cutting blade engages the un-notched portions of the sheet formed against the planar wall of the striker bar to form the severed hinge line.
Dependencies are inferred from the claim text.