Easy Opening Container Wall

Abstract

An easy opening container wall including a main score line in the container wall defining a panel removable therefrom and a tab connected to the panel to initiate severance of the panel. A plurality of generally radially extending secondary score lines are formed in the panel and sections of the panel are preferably axially offset relative to each other.

Description

BACKGROUND OF THE INVENTION

An easy opening container wall typically includes a container wall of sheet material having a main score line therein defining a panel removable therefrom and a tab to initiate severance of the panel from the container wall. Often times the panel is large relative to the size of the container wall and it may cover a major portion of, or substantially all of, the area of the container wall.

During transit the easy opening container is subjected to shock and vibration forces as a result of product movement within the container. Specifically the usual shocks encountered during transit causes the product to be repeatedly forced against the container wall.

The stress thus imparted to the container wall is not evenly distributed throughout the container wall because of the irregular cross section of the container wall due to the weakening of the container wall by the main score line. Rather, the stress is concentrated at the main score line. This repeated stressing of the main score line is so substantial that it can result in the rupture of the sheet material along the main score line, through fatigue or otherwise, with consequent spillage and/or spoilage of the product. In some instances the rupturing along the main score line will be assisted by a positive or negative pressure within the container.

SUMMARY OF THE INVENTION

The present invention solves this problem by reducing the stressing of the container wall along the main score line. This is accomplished by distributing the stress more evenly throughout the container wall thereby reducing the stress which must be absorbed by the sheet material along the main score line. Thus, the stress concentration which existed heretofore along the main score line is eliminated.

To distribute the stress, the present invention teaches weakening of the panel at selected regions so that the weakened regions will absorb greater proportions of the stress than they would in an unweakened state. In this manner the stress is distributed to various regions of the panel with consequent reduction in stress along the main score line. The weakened regions serve to protect the main score line.

The weakened regions are preferably in the form of generally radially extending secondary score lines. In a preferred form of the invention, the weakened regions are substantially evenly spaced circumferentially and extend from locations spaced outwardly of the center of the panel to terminate radially inwardly of the main score line. The weakened regions and the main score line preferably do not intersect because intersection of score lines in a panel can result in leakage of the product through such intersection. However, the weakened regions preferably extend to a location closely adjacent the main score line. By so doing the weakened regions can absorb greater proportions of the stress to thereby give greater protection to the main score line.

The formation of the secondary score lines causes flow of metal away from or outwardly of the secondary score lines. This produces excess metal in the regions of the panel adjacent the secondary score lines. The presence of excess metal renders the container wall bistable, i.e., it produces a tendency of the container wall to "oil can."

To avoid this problem, the present invention teaches axially offsetting sections of the panel. The offsetting of the sections of the panel causes stretching of the panel to, in effect, use up at least some of the excess metal produced by the formation of the secondary score lines.

This can be advantageously accomplished by offsetting or stretching of the panel across the secondary score lines so that the stretching will occur at regions where the excess metal exists. To use up the excess metal adjacent the radial inward ends of the secondary score lines, another section of the panel inwardly of the secondary score lines is preferably axially offset.

Because the offsetting of the panel is for the purpose of utilizing the excess metal produced during the formation of the secondary score lines, the offsetting operation should not occur prior to the operation in which the secondary score lines are formed. Preferably, the offsetting of the panel occurs following the formation of the secondary score lines. To avoid excessive weakening of the panel, the secondary score lines should have a higher residual than the main score line. Of course, the shape, length, spacing, and depth of each of the secondary score lines can be varied depending upon the results desired.

The invention, both as to its organization and method of operation together with further features and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying illustrative drawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view of an easy opening container wall constructed in accordance with the teachings of this invention.

FIG. 2 is an enlarged fragmentary sectional view taken along line 2--2 of FIG. 1.

FIG. 3 is an enlarged fragmentary sectional view similar to FIG. 2 illustrating an initial operation in the method of making the easy opening container wall of FIG. 1.

FIG. 4 is an enlarged fragmentary sectional view taken along line 4--4 of FIG. 3.

FIG. 5 is an enlarged fragmentary sectional view taken on an axially extending plane through a portion of the easy opening container wall which has the main score line.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings and in particular to FIG. 1 thereof, reference numeral 11 designates an easy opening container wall constructed in accordance with the teachings of this invention. The easy opening container wall 11 includes a container wall 13 in the form of a can end constructed of sheet material such as an aluminum alloy and having a peripheral attaching flange 15 to secure the container wall to a can body (not shown). A line of weakness in the form of a main score line 17 is formed in the container wall 13 and defines a tear portion or panel 19 which covers a substantial area of the container wall 13. Although the main score line 17 and the panel 19 may assume various configurations and sizes, in the embodiment illustrated they are circular in plan and the panel 19 covers substantially all of the area in plan of the container wall 13.

A tab 21 is attached to the panel 19 by suitable means such as a rivet 23. The tab 21 constitutes means for manually removing the panel 19 from the container wall 13, and although a specific form of tab has been illustrated, it should be understood that various other kinds of tabs suitable for removing the panel 19 may be utilized.

In the embodiment illustrated, the tab 21 includes a substantially longitudinally rigid lever portion 25 through which the rivet 23 projects to attach the tab to the panel 19. The lever portion 25 includes a rupturing nose 27 which preferably overlies a region of the score line 17 and which can be forced thereagainst to initiate severance of the panel 19 from the container wall 13. Specifically, the score line 17 is ruptured by the rupturing nose 27 which forces a portion of the panel 17 inwardly.

The tab 21 also includes a handle portion 29 integrally joined to the lever portion 25 by a pliable connection portion 31. The tab 21 can advantageously be integrally constructed from a single piece of sheet material such as an aluminum alloy.

To remove the panel 19, the user grasps the radial outer end of the handle portion 29 and moves the latter upwardly, i.e., away from the panel 19. Such upward movement of the outer end of the handle portion 29 can easily be accomplished because the connecting portion 31 is readily bendable. When the handle portion 29 has been elevated above the panel 19 at an appropriate angle, the user can firmly grasp the handle portion and exert an outward pulling force with the result that the end of the lever portion 25 remote from the rupture nose 27 is elevated. This causes the lever portion 25 to pivot with the result that the rupturing nose 27 is forced against the panel 19 with sufficient force to sever the sheet material of the container wall 13 along the score line 17. Then, by exerting a pulling force in the appropriate direction, the entire panel 19 may be removed from the container wall 13.

The panel 19 also includes a plurality of radially extending secondary score lines 33. The score lines 33 weaken the panel 19 inwardly of the main score line 17. Although the particular configuration of the score lines 33 can be varied, in the embodiment illustrated the secondary score lines are linear and extend along radial lines. To obtain the best stress distribution, the secondary score lines 33 are preferably substantially equally spaced circumferentially and preferably extend to locations closely adjacent the main score line 17. The number of secondary score lines 33 can be varied depending upon the results desired and the particular number shown in FIG. 1 should not be considered limiting.

The panel 19 has an inner section 35, an intermediate section 37, and an outer section 39 with the inner and intermediate sections being integrally connected by a connecting section or wall 41 and with the intermediate and outer sections being integrally connected by a connecting section or wall 43. In the embodiment illustrated, the inner section 35 is circular and the intermediate section 37 and the outer section 39 are both annular. Each of the secondary score lines 33 preferably extends from a location slightly radially outwardly of the connecting section 41 across major portions of the sections 37, 43 and 39 to terminate at locations closely adjacent and spaced radially inwardly of the main score line 17. Each of the secondary score lines 33 defines a secondary residual web 45 (FIGS. 2 and 4) and the main score line 17 defines a main residual web 46 (FIG. 5). The residual web 45 is preferably thicker than the residual web 46.

With the container wall 13 scored as shown in FIG. 1, the secondary score lines 33 constitute weakened regions and the zone of the sheet material between adjacent secondary score lines constitute panel segments integrally joined at least in part by the sheet material along the secondary score lines. In use of the easy opening container wall 11, the product (now shown) contained within the container body (not shown) to which the easy opening container wall 11 is attached will move during transit of the container. Such movement of the product within the container inevitably results in the application of repeated forces to the panel 19. If the secondary score lines 33 were not provided, the sheet material along the main score line would be substantially repeated stressed by such movement of the product. However, due to the weakening of the panel 17 by the secondary score lines 33, the panel has numerous regions other than the main score line 17 which can resiliently flex to absorb some of the force applied against the panel 19. Thus, the secondary score lines 33 cause a more even distribution of the stress throughout the panel 19 than would be obtained if the score lines were not provided.

An early operation in the making of the easy opening container wall 11 is illustrated in FIG. 3. First, the container wall 13 is scored to form the main score line 17 and the secondary score lines 33 as shown in FIG. 3. These scoring operations may be carried out simultaneously or sequentially with either the main score line or the secondary score lines being first formed. During the scoring of the secondary score lines 33, metal is displaced outwardly from each of the score lines 33 in all directions. This causes the presence of excess metal in a zone which completely surrounds each of the secondary score lines 33.

Because of the relatively large number of the secondary score lines 33, if this excess metal condition were allowed to remain, the container wall 13 would be bistable. The present invention eliminates the bistable condition of the container wall 13 by axially offsetting the sections 35, 37 and 39 of the panel 19, i.e., by panel forming. As shown in FIG. 2, the intermediate section 37 is offset axially inwardly from the outer section 39 and the inner section 35 is offset axially inwardly from the intermediate section 37. This axial offsetting of the panel sections 35, 37 and 39 stretches the metal along and adjacent the connecting sections 41 and 43.

This stretching which occurs during the panel forming operation removes at least some of the excess metal from the zone surrounding the secondary score lines 33. For this reason, the connecting section 43 preferably extends generally through a central region of each of the secondary score lines 33 so that it can be most effective in drawing or utilizing the excess metal produced in the panel 17 by the formation of the secondary score lines. The connecting section 41 is located slightly radially inwardly of the inner radial end of the score lines 33 so that it can use the excess metal which is adjacent and between the inner ends of the secondary score lines. Of course, variation in the location and number of the connecting sections can be varied, and the configuration illustrated should be considered exemplary of a preferred manner of removing the excess metal.

Because panel forming utilizes excess metal formed during the scoring of the secondary score lines, the panel forming operation should occur simultaneously with, or subsequent to, the secondary scoring operation. However, to score and panel form simultaneously would present difficult tooling design problems and for this reason it is preferred to panel form after the secondary scoring operation.

Although an exemplary embodiment of the invention has been shown and described, many changes, modifications and substitutions may be made by one having ordinary skill in the art without necessarily departing from the spirit and scope of this invention.

Claims

What is claimed is:

1. In an easy opening container wall wherein a line of weakness is formed in a container wall to define a panel at least partially removable from the container wall and a tab is connected to the container wall to initiate severance of the panel from the container wall and wherein the container wall is subjected to a force prior to manipulation of the tab which stresses the line of weakness, the improvement to reduce the amount of stress which will be absorbed by the container wall at the line of weakness in response to the application of the force to the container wall comprising:

the panel being weakened at selected regions thereof with the weakened regions of said panel absorbing some of the stress resulting from said force to thereby reduce the amount of stress which is absorbed by said line of weakness, said panel being nonrupturable at said selected regions by manipulation of the tab, said panel including first and second panel sections offset axially from each other and at least one of the weakened regions lies partially in both of said sections.

2. In an easy opening container wall wherein a main line of weakness is formed in a container wall to define a panel at least partially removable from the container wall and a tab is connected to the container wall to initiate severance of the panel from the container wall, the improvement comprising:

a plurality of secondary lines of weakness in said panel, said panel being nonrupturable along said secondary lines of weakness in response to manipulation of the tab to sever the main line of weakness; and

each of said secondary lines of weakness beginning at a location spaced from the center of said panel and extending generally radially outwardly toward the main line of weakness to terminate in spaced relationship to said main line of weakness, said panel including first and second axially offset sections with at least one of said secondary lines of weakness extending at least part way across both of said sections.

3. In an easy opening container wall wherein a main line of weakness is formed in a container wall to define a panel at least partially removable from the container wall and a tab is connected to the container wall to initiate severance of the panel from the container wall, the improvement comprising:

a plurality of secondary lines of weakness in said panel, said panel being nonrupturable along said secondary lines of weakness in response to manipulation of the tab to sever the main line of weakness; and

said panel including inner, outer and intermediate sections with said intermediate section substantially circumscribing said inner section and with said outer section substantially circumscribing said intermediate section said sections being axially offset from each other, said secondary score lines extending substantially across said outer and intermediate sections.

4. An easy opening container wall comprising:

a container wall of sheet material having a main score line therein defining a main residual web, said main residual web defining a panel at least partially removable from the container wall, said panel covering a major portion of said container wall;

a tab attached to said panel to initiate removal of said panel from said container wall by rupturing said residual web;

said panel having a plurality of secondary score lines therein, each of said secondary score lines defining a secondary residual web of greater thickness than said main residual web; and

said panel having an inner section, each of said secondary score lines extending generally radially from a location closely adjacent said inner section to a location closely adjacent the main score line, said secondary score lines being substantially equally spaced circumferentially.

5. An improvement as defined in claim 3 wherein said secondary lines of weakness extend generally radially of the panel.

6. An improvement as defined in claim 5 wherein each of said secondary lines of weakness terminates short of said main line of weakness, said secondary lines of weakness being spaced circumferentially of the panel.

7. An improvement as defined in claim 2 wherein the main line of weakness defines a main rupturable web and each of the secondary lines of weakness defines a secondary rupturable web, a major portion of the main rupturable web being thinner than major portions of a majority of the secondary rupturable webs.