Ring Tab For Easy-open Can

Abstract

A tab for use with an easy-open can end in which the attachment portion of the tab is formed integral with the inner tab bead and is passed below the outer tab bead and extends to a position beyond the outer periphery of the outer bead for attachment to a tear strip by suitable means such as an integral rivet. The attachment portion is sufficiently long to prevent a sharp bending of the tear strip in the area immediately adjacent the rivet.

Description

BACKGROUND OF THE INVENTION

The present invention relates to an easy-opening can end tab in which the attachment portion thereof is formed in such a way as to resist breaking and, when mounted on the can end, increases the ability of the tear strip to withstand bending without fracturing. More specifically, the invention relates to a device which serves to increase the strength of the tear strip in an area thereof within which sharp creases tend to form when easy-open can are improperly opened by a user and also to increase the strength of the tab to prevent the tab from breaking away from the tear strip.

Cans having easy-open ends have become very common in the recent past for packaging beverages, etc. Basically, such cans comprise a body to which an end wall which is suitably attached at the upper periphery thereof to enclose the volume within the body. A removable portion or tear strip is formed in the can end by means of a weakening score which may be ruptured when the can is to be opened. A tab is attached to the tear strip by any suitable means such as an integral rivet. The rivet is formed at a position which is relatively close to the weakening score and, when the tab is lifted, initial rupturing of the score occurs.

The person opening the can then pulls the tab upwardly to sever the tear strip from the can end until either a pour spout is formed or a full panel pull-out, comprising a major portion of the can end, is removed.

Tabs in common use today generally comprise a washer-like member forming a rigid lever which acts against the can end in the area closely adjacent the rivet when a person opening the can lifts the tab. Such tabs are normally formed by punching a metal ring having the general configuration desired from a large sheet of material. The inner and outer edges of the ring are then rolled toward one another under the main body thereof to form inner and outer beads which strengthen the tab and prevent a person from cutting his fingers on sharp metal edges. Such tabs have usually been punched from the sheet of material in such a way that the rivet attachment portion thereof is effectively an extension of the edge of the ring which is to be positioned closest to the rivet. For example, if the tab is to be attached to the panel by a rivet within the central tab opening, the attachment portion has been formed as an integral part of the inner bead. On the other hand, if the rivet is to be situated outside the periphery of the tab, then the attachment portion has been formed as an integral extension of the outer bead.

Whether the attachment portion is formed inside or outside the tab ring, it must be formed, relative to the ring, so that it lies flat on the can end wall to hold the tab to the panel when the rivet is staked against it. During formation of the attachment portion, the metal is therefore worked along a bend line adjacent the tab body at the line along which its direction changes from that in which it is part of the bead to that in which it is flat on the tear strip. This results in a hardening of the metal along that line. If the can is properly opened by the user, the formation of the bend line does not create a problem and does not effect the removal of the tear strip from the end panel.

Normally, when a user lifts the tab, a rupturing of the score line begins to occur in the area of the rivet before the tab has been raised through a very large angle. The user then puts his finger into the central opening of the tab and, by exerting an upward force relative to the can, completes the severance of the score for removal of the tear strip.

Unfortunately, some users have a tendency to life and pivot the tab through a relatively large angle. Sometimes, users pivot the tab through an angle of 180.degree. so that the tab is once again flattened against the can end, but on the opposite side of the rivet. Apparently, they do this in order to rupture as much of the score as possible during the initial opening action. The user must then rotate the tab back toward its initial position so that he can insert his finger into the tab opening to commence the pulling action. When he does this, the attachment portion sometimes breaks along the hardened bend line, requiring that a pliers or similar tool be used to remove the tear strip. Otherwise, the contents must be poured through the small hole created by the initial rupture of the score.

Competitive pressures have resulted in a variety of expedients to reduce the cost of such can ends. One of the more oopular methods employed to obtain this cost reduction has been to use material having greater tensile strength but reduced thickness. In other words, the materials used in the can ends are thinner, but proportionately stronger, than those used previously. Unfortunately, this combination of properties also causes them to be more brittle.

Therefore, not only is the attachment portion hardened along its bend line by working, but the material originally employed is more brittle to begin with. Thus, there is an increased possibility that the attachment portion will break in such circumstances.

Since the can end walls, and consequently the tear strips, are relatively thin, rotation of the tab through a large angle may also cause a relatively sharp crease to be formed in the tear strip metal along a bend line which is closely adjacent the attaching rivet and immediately adjacent the tab leverage point. The bend line, extending between opposite legs of the score, is usually rather short since the opposite legs of the score are very closely spaced in that area. Since the tear strip metal is very brittle due to its originally selected properties, the working of the metal which occurs when the can is improperly opened as described above, may result in the creation of stresses along the tear strip bending line which are great enough to cause the tear strip to break along that line.

As a result, a person opening a can in this manner is often unable to remove a major portion of the tear strip either because the tab becomes separated from the tear strip or because the tear strip itself breaks.

In the past, attempts have been made to increase the width of the bending line which occurs in the tear strip in order to prevent the formation of a sharp crease. One such attempt has involved the method of installing a reinforcing bead in the area in which the crease is normally formed and which extends in the general direction of rotation of the tab. Such beads have been formed, simultaneously with the formation of the score, by a punching-type operation which deforms and stretches metal in the tear strip to form an offset bead or panel across the crease area.

Such stretching of the tear strip metal causes its thickness to be reduced still further and that portion between the bead and the legs of the score to be placed in tension. The reduction of the thickness of the tear strip reduces its ability to withstand bending and a sharp, easily broken, crease may still be formed therein. Even more importantly, however, since the metal between the bead and the score legs is in tension, the bead formation results in the formation of microscopic cracks in the score. When these cracks form, air-contamination of the contents of the can may occur and, for example, a beverage in the can will become "flat."

An improved method of preventing breaking of the tear strip has been devised in which a coined column is formed in the area of the bend line just prior to the time the score is formed. The coining causes the metal in the area of the score to be placed in compression so that when the score is formed, such microscopic cracks do not occur. This expedient appears to be quite successful in preventing a breaking of the tear strip, but does not prevent a breaking of the tab attachment portion.

Thus it has been found to be desirable to provide a device which will prevent both the attachment portion and the tear strip from breaking during improper opening of the can ends.

SUMMARY OF THE INVENTION

The present invention relates to an improved tab for removing the tear strip or panel from an easy-opening can end. More specifically, the invention relates to such a tab which is so formed as to prevent the tear strip and the rivet attachment portion from being broken if the can end should be improperly opened.

Tabs formed in accordance with the present invention generally comprise what has become known as "ring tabs" which may have any of the well-known configurations. In particular, tabs formed in accordance with the present invention are provided with an extension which is integral with the inner bead of the ring and extends beyond the periphery of the tab for attachment to a tear strip by suitable means such as an integral rivet. Thus, there is no preformed sharp bend line in the attachment portion.

The attachment portion is sufficiently long that it extends along the tear strip a substantial distance beyond the rivet. As the tab is lifted away from the can to cause initial rupturing of the score, the inner bead of the tab exerts an angular pulling force on the attachment portion as the pivoting of the tab occurs. This force causes the attachment portion to tend to become wrapped around the outer bead of the tab, forcing it downwardly toward the can end to suitably stress the score and rupture it. This occurs because the lever pivot axis is not coaxial with the line along which the attachment portion becomes part of the inner bead.

If the tab is provided with the well-known pair of lever arms at either side of the attachment portion, rotation of the tab causes the lever arms to press downwardly on the main panel of the can end while the attachment portion is pulling upwardly on the rivet, thereby rupturing the score. On the other hand, if a substantially round ring is used as the tab, the outer bead will press downwardly on the top of the rivet at the same time that the attachment portion is pulling upwardly along the base of the rivet. Since the attachment portion extends well beyond the rivet, the planar contact between the attachment portion and the tear strip will effectively increase the thickness and strength of both. Therefore, the rivet and the abutting portions of the tear strip and attachment portion will act to prevent the formation of a sharp crease in either the attachment portion or tear strip if the tab should be improperly pivoted when the can is opened.

It will be realized by those skilled in the art that the increased length of the attachment portion is formed from material within the center of the ring formed by the tab and, in manufacturing tabs today, that material is usually waste or scrap. Additional savings may thus be realized since the formation of the attachment portion from the material within the ring may result in less scrap being formed between the periphery of successive rings.

Thus, tabs formed according to the present invention allow the attachment portion to be in planar contact with the tear strip over a relatively large area so that the possibility of breaking either the tear strip or the tab attachment portion are significantly reduced.

The full scope of this invention, together with its further objects, advantages, modes, and embodiments, will be understood by those skilled in the art through reference to the Detailed Description and accompanying drawings which illustrate what are presently considered to be preferred embodiments of the best mode contemplated for utilizing the novel principles as defined in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a top plan view of a can end showing a ring tab, formed in accordance with the present invention, attached thereto;

FIG. 2 is a partial sectional view of the can end of FIG. 1, taken along a line II--II thereof;

FIG. 3 is a side view, partly in section, of a can utilizing the present invention, showing the tear strip partly removed;

FIG. 4 is a top plan view of a can end utilizing an alternate embodiment of a ring tab formed in accordance with the present invention;

FIG. 5 is a partial sectional view of the can end in FIG. 4, taken along a line V--V thereof; and

FIG. 6 is a view, similar to FIG. 5, illustrating the opening of a can end utilizing this form of the invention.

DETAILED DESCRIPTION

Referring now to FIG. 1, there is shown a can end 11 which may be suitably attached to a can by means of a flange 13. A score 15 is formed in the end wall to define a removable tear strip or pull-out panel 17. A ring tab 21 is attached to the tear strip 17 by any suitable means such as a well-known integral rivet 23.

Tab 21 is provided with a pair of lever arms 25 positioned on either side of an attachment portion 27, which latter is staked to the tear strip by means of the rivet 23.

As shown in FIG. 2, the tab generally comprises a ring-shaped member having an inner bead 29 and an outer bead 31 which may be formed by rolling the inner and outer periphery of a washer-shaped stamping. The beads provide strengthening support for a main section 33 of the tab so that it will act as a solid member when a user opens the can. The beads also allow the edges of the washer-shaped ring to be so positioned that a person opening the can is unable to cut himself on the sharp edges of the ring. A portion of the inner bead 29 intermediate the lever arms 25 is not rolled against the main portion 33 of the tab, but is extended beyond the periphery of the outer bead 31 to form the attachment portion 27 so that the tab may be attached to the can end by the rivet 23, as shown in FIG. 2.

When the right end of the tab, as viewed in the drawing, is lifted by a user, the entire tab begins to rotate about the ends of the levers 25. This causes an upward lever force to be exerted on the rivet 23 as the attachment portion 27 presses into a tight, curling contact about the outer bead 31.

The attachment portion 27 is in close planar contact with the tear strip 17 so that the thicknesses, and thus the strength, of both elements are effectively increased. This causes them to act together to resist the formation of a sharp bend line in either of them. Further, since the attachment portion comes from the internal portion of the tear strip and no hardened bend line is formed during the manufacture thereof, breakage of the attachment portion due to improper opening is also effectively obviated.

Referring now to FIG. 4, there is shown a can end 51 having a tear strip 53 defined by a score 55 thereon. A ring tab 57 is attached to the tear strip 55 by suitable means such as a rivet 59 which holds an attachment portion 61 of the tab against the face of the tear strip.

In FIG. 5, it is shown that the tab 57 comprises a central portion 65 having an outer bead 67 and an inner bead 69. The attachment portion 61 is an integral extension of the inner bead 69 so that when the tab 57 is lifted away from the can end, the outer bead rolls onto the rivet 59 and the attachment portion pulls up on the bottom of the rivet to rupture the score 55.

With this tab, the rivet and the attachment portion 61 are both positioned within the initial bending area of the tear strip so that, if the tab is improperly used during initial rupturing of the score, a relatively wide bend line will be formed and no sharp, breakable crease will be formed in either the tear strip or the attachment portion. The small bend which forms at the intersection of the rivet and the attachment portion will not be sharp enough to break when the tab is moved back to an upright position so that a finger can be exerted into the opening.

Thus, the applicant has disclosed a new and improved tab which prevents the breaking of the tab attachment portion and the tear strip by use of material which would otherwise form scrap when the tab is manufactured. Other embodiments of these inventive concepts will now become apparent to those skilled in the art without exceeding the protected scope of this invention as defined in the following claims.

Claims

Wherefore what is claimed is:

1. A tab for attachment to a tear strip in a wall of a container for manual removal of the tear strip comprising:

a one-piece member of sheet material having a relatively large aperture forming a portion of the member into a ring-like configuration to serve as a handle for manipulating the member,

the rim of said aperture being turned to provide a first inner stiffening bead and to provide a smooth inner circumferential surface for the ring-like portion,

the periphery of said member being turned to provide a second outer stiffening bead and to provide a smooth outer surface for the member, and

an attachment portion, for fastening the tab to the tear strip, formed as an integral portion of said first inner stiffening bead and extending beyond the periphery of and passing below said second outer stiffening bead.

2. The tab of claim 1 including

a pair of fulcrum ends straddling said attachment portion and extending from said second outer stiffening bead to fulcrum against the end wall of the container to exert lifting force on the attachment portion and initiate severance of the tear strip.

3. A can end comprising

an end wall,

score means in said end wall,

a tear strip in said end wall defined by said score means,

a rivet formed in said tear strip,

a tab means fastened to said tear strip by said rivet means and having

a ring-like central section,

inner and outer beads formed integral with said central section, and

attachment means formed integral with said inner bead and passing below and outwardly from said outer bead, said attachment means having

an aperture therein through which said rivet extends to hold attachment means against said tear strip.

4. The can end of claim 3 wherein

said attachment means extends a relatively substantial distance beyond said aperture to produce a large radius bend in said attachment means and said tear strip as said tab means is pivoted to remove said tear strip.

5. A tab for removal of a tear strip from an easy-opening can end comprising

a ring-like member having

a first inner stiffening bead formed on the interior thereof and

a second outer stiffening bead formed at the exterior thereof,

said first inner stiffening bead having

an attachment means integral therewith passing below said second outer stiffening bead and outwardly beyond the periphery thereof.

6. The tab of claim 5 wherein

said attachment means comprises

a strip-like member extending beyond said second outer stiffening bead and

an aperture in said strip-like member for receiving a rivet boss therein,

said strip-like member extending a relatively substantial radially outward distance beyond said aperture.

7. The tab of claim 6 wherein

said aperture is sufficiently close to said second outer stiffening bead that the latter will contact the upper surface of a rivet staked in said aperture when the tab is rotated to open the can.

8. The tab of claim 6 including

a pair of fulcrum arms formed integral with said second outer stiffening bead and straddling said attachment means.

9. In a tab for attachment to a tear strip in a container end wall and comprising a central section formed integral with an inner stiffening bead and an outer stiffening bead,

an attachment means formed integral with one of said inner and outer stiffening beads and extending in a substantially radial direction, below said central section and the other of said inner and outer stiffening beads, beyond the perimeter of the other of said inner and outer stiffening beads.

10. The tab of claim 9 wherein

said attachment means further includes

an aperture for receiving a rivet boss therein, said aperture being so positioned in said attachment means relative to the other of said inner and outer stiffening beads as to allow staking of a rivet boss extended therethrough.