Digitally openable container closure

Abstract

A construction for a digitally openable container closure which includes at least one inwardly displaceable opening panel each of which is defined by a fracturable web forming a locus of separation of the opening panel from the adjacent portion of the closure, an integral deflectable portion projecting outwardly from the closure adjacent the fracturable web around each opening panel and weakening lines in the closure adjacent each opening panel extending across the closure between the opening panel and a central panel of the closure to facilitate displacement of the deflectable portion of the wall in response to digitally applied inwardly directed pressure to initiate fracture of the web and permit inwardly displacement of a separated opening panel.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to containers and container closures and in particular to a container closure for liquid contents under pressure and having inwardly one or more displaceable opening panels in the closure for forming pouring and/or vent openings therein.

2. Brief Description of the Prior Art

Many billions of metal cans are fabricated each year to contain, preserve and transport beverages, such as soda and beer. Many of these cans include easy opening devices for forming pouring openings in the can ends without the need for special tools. These easy opening devices typically include a tear strip with a pull tab attached thereto by means of an integral rivet. The widespread utilization of easy opening devices of this type has created problems due to the hazards attendant the relatively sharp-edged removable tab portion thereof and the propensity of consumers to indiscriminately dispose of such tabs immediately following their separation from the containers.

The prior art, and notably the patent art, is replete with hundreds of suggested expedients for achieving the long desired objective of simplified can opening, including many suggested expedients for can closures that can be digitally opened, i.e., manually opened without the use of auxiliary tools or the like. Included in such expedients are container walls and end closures having weakening lines or score lines defining tear strips or panels which can either be depressed into or pried out of a container to form either a vent or a pouring opening. Closures of this type are exemplarily disclosed in a number of U.S. Pat. Nos. including Newman 1,805,003, Fink 2,119,533, Punte 2,120,186, Fried 2,176,898, Punte 2,187,433, Punte 2,289,452, Punte 2,312,358, Punte 2,312,359, Asbury 3,227,304, Asbury 3,246,791, Klein et al 3,334,775, Asbury 3,355,058, Geiger 3,362,569 and Foss et al 3,410,436. Such end closures have sometimes required the use of rigid tools such as a coin or fork, to rupture the score line around the removable panel in order to form an opening in the end closure. U.S. Pat. Nos. 3,381,848, 3,404,801 and 3,422,983 disclose auxiliary score lines for reducing the force required to initiate rupture of primary score lines around tear strips in container walls.

It has been suggested as is disclosed in U.S. Pat. Application Ser. No. 357,937, filed May 7, 1973, entitled "Method of Forming and a Construction for a Digitally Opening Container Closure" to form a container end closure including a particularly contoured fracturable web defining an inwardly displaceable opening panel having an upper surface on the rim thereof intersecting the inner marginal edge of the lip of an adjacent particularly contoured deflectable portion in a first exposed corner and with the undersurface of the lip disposed in substantial alignment with the upper surface of the panel rim and intersecting the outer marginal edge of the rim in a second corner. The deflectable portion is integral with the container wall, projects outwardly from the plane of the container wall adjacent the fracturable web and is adapted to effect, in response to digitally applied inwardly directed pressure thereon, relative displacement of the lip and rim to strain the web and initiate fracture thereof. When such a container closure is sealed on a can of beer or soda under pressure, the pressure in the container causes the closure to dome slightly outward, and the internal pressure resists downward displacement of the deflectable portion in the closures which is desired to initiate fracture of the web around the opening panel. In some containers, the pressure can produce a magnitude of resistance against inward displacement of the deflectable portion of the closure that initiation of fracture of the web can be difficult for the consumer.

An easy opening container component with inwardly displaceable opening panels is desired which can be digitally opened with a minimum of force even when the container on which the component is sealed contains internal pressure in the range of 60 to 90 or more pounds per square inch.

SUMMARY OF THE INVENTION

This invention may be briefly described as including, in its broad aspects, the provision of an improved construction for a digitally openable container end closure. In such broad aspects, it includes a container wall having a particularly contoured fracturable web defining an inwardly displaceable opening panel in the wall adjacent its peripheral edge and at least one weakening line in the wall extending across a portion thereof between the opening panel and a central portion of the wall. The container wall also includes an integral outwardly projecting deflectable portion adjacent the fracturable web. The deflectable portion is adapted to be displaced inwardly to strain the fracturable web and initiate fracture thereof in response to digitally applied inwardly directed pressure.

Among the advantages of the subject invention is the provision of a metal container closure construction that exceeds the stringent present day interrelated economic and performance criteria and which also satisfies ecology-based governmental regulations. More specific advantages include the provision of a highly reliable end closure of reduced metal content that can be fabricated with a minimum number of fabricating steps at high production rates with simple tooling. Further advantages include the provision of an end closure that can be opened by application of modest amounts of digitally applied pressure without the use of auxiliary tools.

Accordingly, an object of this invention is to provide a tabless easy opening container wall which can be opened digitally.

Another object of this invention is to provide a container wall with a fracturable web in it defining an inwardly displaceable opening panel, an adjacent deflectable portion for straining the fracturable web to facilitate initiation of rupture thereof, and weakening lines in the wall for minimizing the force required to displace the deflectable portion.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects of this invention will be more fully understood and appreciated with reference to the following description and the drawings appended hereto wherein:

FIG. 1 is an enlarged top plan view of a can end of the invention.

FIG. 2 is an enlarged partial cross section through the can end of FIG. 1 taken along line 2--2, with the can end double seamed on a container body.

FIG. 3 is a further enlarged cross section of a portion of the opening panel, fracturable web and deflectable portion of the can end illustrated in FIG. 2.

FIG. 4 is a cross section similar to FIG. 2 and further illustrating initiation of opening of the inwardly displaceable opening panel.

FIGS. 5 and 6 are cross sections through dies for forming a fracturable web and deflectable portion around an opening panel in a container wall.

DESCRIPTION OF PREFERRED EMBODIMENT

Referring to FIGS. 1, 2 and 3, a container wall or can end 10 is shown which includes a substantially planar central panel 12, a peripheral groove 14 around the panel, and an upstanding chuck wall 16 outwardly of the groove, and a flange 18 extending outwardly from the top of the chuck wall. Such general construction of a peripherally chimed can end is typical of can ends which are adapted to be sealed on container bodies by conventional double seaming operations. FIG. 2 shows the flange 18 double seamed onto container body 20.

In order to facilitate understanding of the subject invention and in the interest of clarity, the terms "inwardly" and "outwardly" will be herein employed to delineate directions relatively to the interior and exterior respectively of a cylindrical container having the end closure of interest mounted on the end thereof.

Can end 10 includes at least one, and preferably two, inwardly displaceable substantially rigid opening panels 22 of equal size defined by fracturable webs 24 in planar wall 12. The opening panels 22 are designed to be opened by displacing them into a container on which can end 10 is sealed to form a pouring opening and/or vent in the can end. Opening panels 22 are circular and are contoured to include an inwardly domed center portion 26 bounded by a rim 28 peripherally terminating in fracturable web 24. The web 24 interconnects the rim 28 of the opening panel 22 with a lip 30 of an integral outwardly projecting deflectable portion 32 of generally frusto-conical configuration surrounding the opening panel in the adjacent portion of the container wall. As best seen in FIG. 3, rim 28 has a substantially planar upper surface 34 which terminally intersects an angularly inclined surface 36 defining the inner marginal edge of lip 30 of deflectable portion 32 in an exposed corner 38. Lip 30 has a substantially planar undersurface 40 which is disposed in substantially coplanar relation with the upper surface 34 of rim 28 and which terminally intersects an angularly inclined surface 42 defining the outer marginal edge of rim 28 of panel 22 in a second corner 44. The corners 38 and 44 are disposed in predetermined laterally spaced relation and define therebetween the lateral extent of fracturable web 24.

Deflectable portion 32 in container end 10 is adapted to effect, in response to inwardly directed digitally applied pressure, a relative displacement of lip 30 with respect to rim 28 to strain web 24 and initiate fracture thereof to permit inward displacement of a separated opening panel of greater rim size than the size of the opening which is formed in the end. Such inwardly directed digital pressure is best applied against the ends 10 adjacent web 24 and preferably against the raised lip 30 of the deflectable portion 32 as is illustrated in FIG. 4. Such inward pressure against the deflectable portion 32 moves the lip 30 relative to the rim 28 of the opening panel 22 to strain the web 24 and initiate fracture thereof. As pointed out above, the opening panel 22 is preferably of relatively rigid character to resist bending thereof and thereby insure that the displacement of deflectable portion 32 will create sufficient relative displacement of the lip 30 thereof with respect to the rim 28 of the opening panel to initiate web fracture.

In the embodiment selected for illustration (FIG. 1), each fracturable web 24 has generally C-shaped outline with a bridge of metal between the ends of the web defining a hinge 46 which prevents complete separation of the opening panel 22 from the container end 10. The location of the hinge 46 is not important. For example, the hinges 46 may alternatively be provided adjacent the radially outermost extent of each web 24 in the container wall 10.

As is disclosed and claimed in U.S. Pat. Application Ser. No. 318,476, filed Dec. 26, 1972, entitled "Tabless Container Opening Device and Method and Tools for Forming the Same," container end 10 may also include a narrow zone of coined metal 48 extending generally parallel to each fracturable web 24 adjacent each opening panel 22. Coined zones 48 are preferably spaced from the fracturable web 24 a distance approximately one to 3 times the thickness of the metal in the container wall 10 and are located near the top of deflectable portion 32 around each opening panel 22.

In accordance with this invention, means is provided in the can end 10 for facilitating displacement of deflectable portion 32 to initiate rupture of the fracture web 24 around each opening panel 22. In a preferred embodiment, such means comprises score lines 50 adjacent each of the opening panels 22. Each score line 50 extends from a point adjacent the peripheral edge of wall 12 generally toward the central portion of the wall and preferably tangent to coined zone 48 around each opening panel 22. Score lines 50 form a line of weakening extending across the wall 12 between the opening panel 22 and the central portion of the wall 12 so that deflectable portion 32 may be more easily displaced inwardly as is illustrated in FIG. 4.

Internal pressure is container 20 acts against the interior surface of can end 10 to resist inward displacement of the deflectable portion 32 and, in the absence of weakening lines 50, can cause undue difficulty in initiating fracture of web 24 around the opening panel 22. It has been found that providing weakening lines such as score lines 50 in the can end 10 greatly reduces the amount of force required to displace deflectable portion 32 inwardly. It is believed that this reduction in the required opening force results from inward displacement of a smaller area of an end closure having score lines 50 therein than in an end closure not having such weakening lines. Reducing the area which is displaced inwardly reduces the internal force against such area produced by the pressure in the container. This means that the digitally applied force required to deflect such area to initiate fracture of web 24 is resisted by and overcomes a smaller internal force and opening is therefore easier for an end closure including weakening lines 50 than for one not including such weakening lines.

Score lines 50 have been found to reduce the opening force by approximately 30 percent as compared to similar can ends which include no such weakening lines. In one test, can ends with weakening lines 50 in them which were sealed on containers having approximately 80 pounds per square inch internal pressure, required approximately 11.5 pounds of force to initiate fracture of the web around an opening panel, whereas similar can ends without such weakening lines required approximately 15 pounds of force to initiate fracture of the web. In another test, the force required to initiate fracture of the fracturable web averaged approximately 7.5 pounds for pressurized cans with ends having weakening lines 50 in them and approximately 12.5 pounds for pressurized cans not having such weakening lines in them.

The exact location of weakening lines 50 is not critical to this invention. It is believed that the weakening lines should generally follow a line along which the panel 12 will normally bend when force is applied against deflectable portion 32 at the location of either of the X's in FIG. 1. The letter "X" may be stenciled on the can end 10 to show the consumer where pressure is most advantageously applied against the end.

The weakening lines may comprise a line of reduced metal thickness as in a coined zone or score line, but may also comprise a groove or other weakening of the metal of container wall. Score lines having a depth in a range of 0.002 inch to 0.006 inch, and preferably a depth of 0.0025 inch and a residual of 0.0105 inch in a can end having a nominal thickness of 0.013 inch will provide the desired degree of weakening in the wall. If the residual metal in the line of weakening is too thin, the container end may be weakened to such an extent that it will be vulnerable to outward doming or buckling when the container end is sealed on a container with internal pressures of approximately 60 to 90 or more pounds per square inch as is common to containers of beer and carbonated beverages.

The length of each weakening line 50 is also not believed to be critical to this invention as they may have any length which will provide the necessary flexibility in the panel to facilitate inward displacement of deflectable portion 32. The weakening lines 50 may also be formed in either the exterior or interior surface of the can end 10. A plurality of weakening lines disposed substantially parallel to weakening lines 50 may also be beneficial to reducing the amount of force required to displace deflectable portion 32 inwardly on a container. In the embodiment selected for purposes of illustration, two score lines 50 are provided adjacent opening panel 22 with the score lines 50 forming an obtuse angle of approximately 120.degree. open toward the adjacent panel 22, although departure therefrom can be tolerated. The score lines 50 could also be joined to form a continuous line across the container wall.

FIGS. 5 and 6 illustrate exemplary tools and a preferred method for forming the particularly contoured fracturable web and deflectable portion in a can end. The fracturable web and deflectable portion may be formed either at the same time the can end is blanked and drawn from a sheet of metal or may be formed in the can end subsequent to such blank and draw operation. The weakening lines of this invention, such as weakening lines 50 illustrated in FIG. 1, and any stenciling are preferably formed in the sheet metal prior to forming of the fracturable web and deflectable portion. The weakening lines such as score lines 50 may be formed by conventional scoring tools which need not be illustrated and described in this application because such tools are within the knowledge of those skilled in the art of making easy opening devices.

The exemplary tools illustrated in FIGS. 5 and 6 comprise a vertically movable annular top die 52 and an annular bottom die 54 between which a metal sheet or a container wall 56 is positioned to have a fracturable web and deflectable portion formed therein to define an opening panel. The tools further include an auxiliary vertically movable outer annular doming and coining tool 58 for coining the container wall adjacent the fracturable web and controlling the direction in which a deflectable portion is formed in the container wall. Although die 58 is illustrated as being separate from die 52, the two dies may be an integral unit.

The important surfaces on top die 52 comprise a first substantially planar horizontal bottom face or base surface 60, and a second and angularly disposed substantially planar metal extruding surface 62 which preferably extends outwardly from the first base surface 60 at approximately a 45.degree. angle, although limited angular departure therefrom may apparently be tolerated. The first base surface 60 and the second metal extruding surface 62 of the top die 52 meet at a relatively sharp corner 64 so that a similar sharp corner will be formed in the container wall. The bottom die 54 has a first substantially planar base surface 66, a downwardly inclined outer face 68 to permit the formation of a deflectable portion adjacent the opening panel and a second and angularly disposed substantially planar metal extruding surface 70 extending downwardly from the first base surface 66 at approximately a 45.degree. angle. The base surface 66 and metal extruding surface 70 preferably meet at a relatively sharp corner 72 as do the die surfaces in the top die. Metal extruding surfaces 62 and 70 on top and bottom dies 52 and 54 are preferably substantially parallel, although limited departure therefrom can apparently be tolerated.

Doming and coining tool 58 has a coining bead or rib 74 for coining the container wall adjacent the fracturable web which is formed by the dies. The coining rib 74 may be arcuate in cross section as is illustrated or may have other configurations which will squeeze metal against the bottom die 54. Coining metal between the coining rib 74 and surface 68 on the bottom die 54 causes metal to flow laterally from between the rib and die surface and is believed to in some way control the stresses which are produced in the container wall in forming a fracturable web therein. Auxiliary die 58 also has a base surface 80 thereon for shaping or controlling the formation of a deflectable portion in a container wall.

In forming a fracturable and deflectable portion in a container wall, the container wall is positioned between the dies 52, 54 and 58, and the dies are closed to form the sheet metal therebetween. Faces 60 and 66 on die 52 and 54 respectively displace or move metal in the sheet at substantially right angles to the original undisplaced surface of the sheet to form the fracturable web. Metal is extruded from between the angularly offset metal extruding surfaces 62 and 70 on the dies to cause lateral metal flow or extrusion of metal away from the fracturable web while metal is being displaced at substantially right angles. The described lineal displacement of the top die members 52 and 58 toward the lower die member 54 continues until the first base surface 60 on die 52 is disposed substantially coplanar with the first base surface 66 on the lower die member 58. Lateral metal flow away from the fracturable web 76 that is formed produces an increased surface area of metal in the container wall for forming the deflectable portion 78 in the metal container wall 56 adjacent the web fracturable 76 (FIG. 6). In forming the deflectable portion 78, the auxiliary die means 58 is lineally displaced to selectively move the base surface 80 thereof into predetermined longitudinally offset relations with respect to the first base surface 66 of the lower die member 54 in the direction of die displacement to form the deflectable portion 78 therebetween.

The lateral spacing between the corners 64 and 72 of dies 52 and 54 defines the lateral extent of the fracturable web 76 which is formed in the container wall 56. Such lateral spacing may be in the range of approximately one-sixteenth to one-fourth of the nominal metal thickness in the container wall.

The coining rib 74 on the auxiliary die member coins the metal adjacent the fracturable web and forms a zone of coining along the fracturable web 76. Coining the metal in the coined zone may reduce its thickness by a few thousandths of an inch.

The domed shape of opening panel 84 is formed as a result the lateral extrusion of metal from between die surfaces 62 and 70 which increases the surface area of metal in the container wall. In the dies selected for illustration, the downward travel of die member 52 causes the opening panel 84 to be downwardly convex in the container wall.

This invention is particularly well suited for use with container walls made of work hardened aluminum base alloy sheet material in the thickness range of 0.010 inch to 0.015 inch and which is at least quarter hard, and preferably at least three-quarter hard temper as may be produced from extra hard temper alloy which has been partially annealed as a result of heating it to cure a protective coating thereon. Such metal has a relatively high tensile strength which resists bending or deformation thereof. It is believed that such work hardened alloy sheet material is particularly well suited to the practice of the invention because material of the specified hardness is required to insure conversion of the inwardly directed digitally applied pressures into selectively directed displacement of the lip of the deflectable portion relative to the rim of the relatively rigid opening panel to initiate fracture of the web. However, the strength of the material in combination with internal pressure in a container can produce substantial resistance against inward displacement of the deflectable portion in a container wall. The weakening lines of this invention neutralize or counteract such resistance and facilitate inward displacement of the deflectable portion of a container wall by bending of the container wall along such weakening lines.

Although a preferred embodiment of a container wall has been selected for illustration and description, it will be apparent to those skilled in the art that numerous variations could be made therein without departing from the invention.

Claims

What is claimed is:

1. A sheet metal container component having a generally planar wall with at least one relatively rigid inwardly displaceable opening panel in said wall bounded in substantial part by a fracturable web defining a locus of separation of said opening panel from the adjacent portion of said wall, an integral deflectable portion projecting outwardly from said container component adjacent said fracturable web in surrounding relation with said opening panel and relatively easily deflected in comparison with the opening panel and at least one weakening line in said wall adjacent said opening panel and extending across at least a portion of said wall on the side of the opening panel toward the center of said wall and ends thereof extending in generally opposite directions toward the peripheral edge of the wall to facilitate displacement of said deflectable portion and said wall in response to digitally applied inwardly directed pressure to strain said web and initiate fracture thereof to permit inward displacement of a separated opening panel.

2. A sheet metal container component as set forth in claim 1 in which said weakening line forms an obtuse angle open toward said opening panel.

3. A sheet metal container component as set forth in claim 1 in which said weakening line comprises a line of reduced metal thickness.

4. A sheet metal container component as set forth in claim 1 in which said weakening line comprises a score line in the metal.

5. A sheet metal container component as set forth in claim 1 which includes two opening panels adjacent opposite edges of said wall and at least one weakening line in said wall adjacent each said opening panel on the side thereof toward the other opening panel.

6. A sheet metal container component as set forth in claim 1 which includes a zone of coining adjacent said fracturable web around the opening panel and two weakening lines extend from opposite sides of the opening panel generally toward a central portion of said container component tangential to said zone of coining.