Easy opening closure for containers

Abstract

This disclosure relates to an easy opening closure for containers of the type having a displaceable panel portion defined by a weakening line and wherein a pull tab is secured to the displaceable panel portion for effecting the rupture of the closure along the weakening line and the displacement of the panel portion thereof. A pull tab is secured to the displaceable panel portion by means of securing means such as a rivet and is subject to turning so as to render the same ineffective. The pull tab is interlocked with the displaceable panel portion by a simple punching operation which forms a projection on the underside of the pull tab and a like configurated socket in the panel portion receiving the projection.

Description

This invention relates in general to new and useful improvements in easy opening closures for containers, and more particularly to a means for securing a pull tab against rotation about a securing rivet and thus maintaining the alignment of the pull tab with respect to the usual weakening line defining a displaceable panel portion.

It has been known in the past to provide means for preventing rotation of the pull tab relative to the rivet by providing wart-like indentations in the pull tab adjacent the rivet receiving opening thereof, and when the pull tabs are applied to a removable panel portion, the projections defining the wart-like indentations are pressed against the underlying panel portion under a relatively high pressure due to the securement of the pull tab in place by the rivet to produce slight indentations in the displaceable panel portion receiving the projections defined by the wart-like indentations.

By the engagement of the indentations in the depressions, there has been achieved the result that the pull tab cannot twist out of a predetermined relative position on the closure. The predetermined position is one wherein the nose of the pull tab has a specific relative position with respect to the weakening line formed in the closure.

It is well known that it is of great significance in the opening process to have the pull tab exactly positioned with respect to the weakening line since even slight deviations from the predetermined position can lead to a considerable raising of the required opening force or in some cases even resulting in the pull tab being torn from the rivet without the opening process taking place.

By indenting the wart-like deformations of the pull tab into the closure panel, a certain security against turning of the pull tab is achieved. However, this security is only small and depends more or less on the relative deformability of the material of the pull tab and on the material of the closure panel adjacent the attaching rivet.

In order to improve the security against turning, a tongue-shaped punching has been provided in the pull tab on the edge of the opening of the pull tab receiving the rivet with the free end of the tongue-shaped punching having been bent downward. The tongue-shaped punching comes to lie below the rivet head and is pressed into the upper side of the closure panel under high pressure during the setting of the rivet head. It has been found, however, that even with this type of turning security only relatively insignificant safety forces can be realized in that once again one has to depend on a large extent on a relative deformability of the materials of the pull tab and the closure panel. It has also been known to provide the pull tab with a generally horseshoe-shaped cut line defining an attaching lug receiving the rivet with the remainder of the pull tab being pivotal relative to the attaching lug. It has been known with this type of pull tab to provide semi-circular recesses on opposite sides of the cut line together with a further semi-circular recess so as to define a circular recess into which a knob, shaped in the panel of the closure, can engage upon attachment of the pull tab to the closure panel. While this arrangement provides for better security against turning, the cost is relatively high since both the closure panel and the pull tab must be provided, each one by itself and prior to assembly, with deformations precisely synchronized with one another.

In view of the foregoing, it is the purpose of this invention to develop an easy opening closure of the type in question which will achieve a very high security force against twisting of the pull tab relative to the securing rivet independently of the materials of the pull tab and the closure panel while at the same time the arrangement is essentially simple and the formation will be less expensive than heretofore.

In accordance with this invention, the difficulty of securing the pull tab against turning relative to the rivet is solved by forming in the areas of the pull tab which lie flatly against the upper side of the closure panel, a center punch mark-like, joint deformation in the materials of the pull tab and the closure panel.

The proposed interlock against turning offers the possibility of the production of a deep, positive engagement of limited points of the pull tab with limited points of the closure panel. Since it is a matter of common deformation, the deformations in the pull tab and the closure panel engage with one another by way of a tight as possible seating and without any clearance, and thus increase the security force. Above all, this security against turning can be accomplished after the final attachment of the pull tab to the closure panel in the same machine so that separate processing steps on the closure panel and the pull tab are not required, and so that there will be no need to make certain that preformed pull tabs equipped with safety elements are utilized with closure panels provided with corresponding safety elements or features.

It has been found that two common deformations, lying diametrically opposed to one another provide effective security against turning. These deformations can be formed in various configurations including those of a cup, a pointed cone, or of an elongated, oval or rectangular configuration with corners. Also, in accordance with this invention, the position of the common deformation is not critical. It has been found that without unduly weakening the metal of the closure panel or the pull tab in any way, the common deformation can also be placed transversely across a cut line defining the attaching lug of the pull tab. Since the common deformation is independent of the attaching process and thus from the formation of the rivet head, it can be formed at any part of the pull tab which lies flatly against the closure panel. In view of this, it is to be understood that the invention is not restricted to a specific pull tab configuration.

With the above and other objects in view that will hereinafter appear, the nature of the invention will be more clearly understood by reference to the following detailed description, the appended claims and the several views illustrated in the accompanying drawings:

FIG. 1 is a fragmentary plan view of a container closure having secured thereto a pull tab and with the pull tab being locked against rotation relative to the securing rivet therefor in accordance with this invention.

FIG. 2 is a transverse sectional view on a large scale taken along the line II--II of FIG. 1 and shows specifically the details of the invention.

Referring now to the drawings in detail, it will be seen that there is illustrated an easy opening closure for containers which includes a removable or displaceable panel portion 1 defined by a weakening line 2 which is disposed adjacent the periphery of the closure. The displaceable panel portion 1 is provided with an integral rivet 3 with which a pull tab 4 is attached to the displaceable panel portion. It is to be noted that portions of the pull tab surrounding the rivet 3 rest flatly against the surface of the displaceable panel portion 1.

The pull tab 4 illustrated in the drawings is shaped from sheet metal and has an annular gripping section 5 which is defined by outside and inside rolls 6 and 7, respectively. The pull tab also includes an attaching section which is rigidly connected to the gripping section 5 and is in the form of an indentation which is defined by a peripheral shoulder 10. The bottom part of this indentation, which bottom is identified by the numeral 11, flatly rests on the upper surface of the displaceable panel portion 1.

It is to be noted that the attaching portion of the pull tab is reinforced on opposite sides of the shoulder 10 by rolls 9 which constitute continuations of the rolls 6. Further, at the forward end of the pull tab there is a projection 8 which generally terminates in a nose overlying and aligned with the weakening line 2.

In the flat bottom 11 of the pull tab, a generally U-shaped or horseshoe-shaped cut line is formed with the ends thereof facing the projection 8 and terminating in rounded ends 12a. The cut line 12 defines an attaching lug in which the customary opening for receiving the rivet 3 is provided. It is to be understood that the pull tab may be hinged relative to the rivet along a fold line extending between the rounded ends 12a with the pull tab functioning as a rigid lever for forcing the nose projection 8 down against the closure panel along the weakening line so as to effect rupture of the closure panel along the weakening line.

It is to be understood that the position of the pull tab, as shown in FIG. 1, relative to the weakening line 2 is of extreme importance for the easy opening of the container. Accordingly, a safety provision against rotation of the pull tab relative to the rivet 3 has been provided in accordance with this invention.

In the illustrated example of the invention, the means for preventing turning of the pull tab relative to the rivet is in the form of a two common deformations 13, 14, in the bottom 11 of the pull tab and in the metal of the closure panel 1, with the two common deformations being essentially diametrically opposed to one another with respect to the axis of the rivet 3. As is apparent from FIG. 2, the indentations are stamped jointly in both the pull tab and the closure panel with the result that they firmly engage one another in a tight fit. As a result of the common deformation, a positive connection between the material of the pull tab and the material of the closure panel will be achieved. Also, this can be accomplished after the position of the pull tab relative to the closure panel has been assured.

It is to be noted that inasmuch as the indentations are formed in a positive manner in the materials of both the pull tab and the closure panel, a selected tearing of the materials of the pull tab and closure panel is not required. Also, the location and shape of the common deformation is not critical although the illustrated embodiment has proven itself to be particularly advantageous. Also, instead of the illustrated circular deformations, elongated, oval formations can be provided and can be disposed generally radially or tangentially in relation to the axis of the rivet 3. Also, while they have not been illustrated, one can employ deformations having a rectangular configuration in plan.

It is to be noted that in accordance with the illustrated embodiment of the invention, the deformations 13, 14 are placed transversely across the cut line 12 without interference with the cut line 12. It is also to be noted that the cut line will extend into the cup shaped portion of the deformation 13 or 14 and thus increase the interlocking between the pull tab and the closure panel by pressing into the deformation 16 of the closure panel.

In view of the fact that the common deformations are produced only after the final attachment of the pull tab, the production of the deformations is independent of the force required for setting the rivet. Despite the subsequent execution of the deformations, a special operating step for this purpose is not necessary. Producing the common deformations can be accomplished in one of the already existing work stations during the automatic production of the easy opening closures through a small change in the tools used there.

It has been found that the force required to turn the pull tab when secured in the foregoing manner is increased many times over that which has been heretofore provided. This is particularly true when the container panel is formed of sheet steel.

Since the production of the deformations is accomplished independently of the attachment of the pull tab, a common deformation can also be made on any other portion of the pull tab and also at a point remote from the attaching rivet, provided, of course, that the pull tab has a metal area at that particular spot which rests flatly on the underlying panel portion 1. The production of the deformation in the area of the indentation or recessed bottom 11 is recommended, however, in that in this position there is no loss of engagement even when there is a slight lifting of the pull tab at the gripping end thereof.

It is also to be understood that the common deformations in accordance with this invention can be formed from the inside of the closure as well as from the outside as is specifically disclosed herein.

Although only a preferred embodiment of the invention has been specifically illustrated and described herein, it is to be understood that minor variations may be made in the invention, as defined in the appended claims .

Claims

I claim:

1. An easy opening closure for containers, said closure comprising a panel, at least one weakening line in said panel defining a displaceable panel portion, a pull tab for effecting the rupture of said panel along said weakening line and the displacement of said panel portion, means securing said pull tab to said panel portion with a part of said pull tab lying flatly against said panel portion, and interlocking means of the projection and socket type in said pull tab part and said panel portion for preventing rotational movement of said pull tab relative to said panel portion about said securing means, said interlocking means having the appearance of being simultaneously formed, said pull tab having a nose generally alignable with said weakening line and a grip portion, said nose and said grip portion being disposed on opposite sides of said securing means, and said interlocking means being disposed between a center of said securing means and said nose and projection being on said pull tab part and said socket being in said panel portion wherein said interlocking means are more forcibly engaged when said grip portion is moved away from said panel portion in a container opening operation.

2. The closure of claim 1 wherein said interlocking means have the appearance of being formed by a center punch.

3. The closure of claim 1 wherein said interlocking means are disposed adjacent said securing means.

4. The closure of claim 1 wherein said interlocking means are disposed adjacent said securing means on opposite sides thereof in like positions.

5. The closure of claim 1 wherein said pull tab is of the type having a cut line therein defining a hinge facilitating pivoting of said pull tab relative to said panel portion, and said interlocking means being formed in said pull tab part bridging said cut line.

6. The closure of claim 5 wherein said interlocking means are disposed on opposite sides of said securing means in like positions.

7. The closure of claim 1 wherein said pull tab includes an integral lug in part separated from the remainder of said pull tab by a cut line defining a hinge between said lug and the remainder of said pull tab facilitating pivoting of said pull tab relative to said panel portion, and at least a part of said projection being formed in said lug.

8. The closure of claim 7 wherein said cut line extends through said projection.

9. The closure of claim 7 wherein said interlocking means are disposed on opposite sides of said securing means in like positions.