US3391820A

US3391820A - Easy open can end

Info

Publication number: US3391820A
Application number: US623941A
Authority: US
Inventors: Omar L Brown
Original assignee: Individual
Current assignee: Individual
Priority date: 1967-03-17
Filing date: 1967-03-17
Publication date: 1968-07-09
Anticipated expiration: 1985-07-09

Description

y 9, 1953 o. L. BROWN 3,391,820

EASY OPEN CAN END Filed March 17, 1967 2 Sheets-Sheet 1 $.2 ArraQ/VJFJ July 9, 1968 o. L. BROWN 3,391,820

EASY OPEN CAN END Filed March 17, 1967 2 Sheets-Sheet 2 M'VJ/Vfdk ma, 1. drawn Irma/vent United States Patent 3,391,820 EASY OPEN CAN END Omar L. Brown, Dayton, Ohio, assignor, by mesne assignments, to Ermal C. Fraze, Dayton, Ohio Filed Mar. 17, 1967, Ser. No. 623,941 13 Claims. (Cl. 220-54) ABSTRACT OF THE DISCLOSURE A tab for severing a full-sized tear panel from a can top is divided by a forward fold into a folded-under rearwardly extending base portion that is attached directly to the panel by two laterally spaced rivets and an upper lever portion having a short and narrow working arm extending forward beyond the fold, the fold serving as a hinge for the lever portion.

Background of the invention The invention relates to an easy opening can end of the type that is commonly termed full panel pull out, meaning a can lid in which the score line defines a tear panel nearly as large in area as the can lid.

In the operation of the pull tab of the character to which the present invention pertains, the severance of the full sized tear panel is accomplished in two steps. In the first step the pull tab functions as a lever to initiate severance of the tear panel by depressing a peripheral portion of the tear panel into the interior of the can. The second step is carried out by using the tab as a handle for exerting pulling force on the tear panel to complete the severance.

It is obviously desirable to make both steps of the severance procedure easy to carry out. It is also highly desirable to avoid depressing any substantial segment of the tear panel into the interior of the can because the result is what may be termed a paddle action that disturbs the contents and may contaminate the contents.

In practice these requirements are interrelated and involve conflicting considerations. The requirement of making the lever action easy would dictate a tab with a favorable leverage ratio, i.e., a lever action with a relatively short forward Working arm and the desirability of avoiding undue paddle action would also dictate a short working arm since the size of the initially depressed segment of the tear panel depends primarily on the length of the forwardly extending working arm.

Unfortunately, however, initially depressing only a small segment of the tear panel by the lever action causes the sheet metal to be severed along only a relatively small arc and if only a small are of metal is severed by the first step it is ordinarily unduly diificult to complete the severance by pulling action on the tear panel.

The problem solved by the present invention is to avoid undue paddle action by initially severing only a small arc of the circular score line and at the same time to find some way to avoid the penalty of making it unduly difficult to carry out the second stage of completing the severance by pulling force.

Summary of the invention The invention provides a lever-action pull tab in which the forward working arm of the lever is both narrow and short to minimize the area of the marginal portion of the tear panel that is bent inwardly by the lever action.

With reference to facilitating the second step of completing the severance of the tear panel by pulling force it has been found that in using a prior art tab for this purpose, an undue amount of energy is diverted into merely resiliently bowing the tear panel out of its initial plane. The present invention minimizes this wasted energy by ice employing the pull tab to stiffen the panel against excessive deformation. For this purpose the pull tab is attached tightly to the tear panel at two points spaced on opposite sides of the longitudinal axis of the tab.

It has been further found that it is usually difiicult to carry out the second step and especially to initiate the second step because the applied pulling force is not efficiently distributed -with reference to the two zones where the severance of the metal is to be continued. Where a pull tab is attached to a tear panel by a single rivet at substantial spacing from the score line, the pulling force tends to be restricted to a narrow radial zone that is remote from the two points where the force must be initially effective, i.e. remote from the two ends of the arc where the metal has been severed by the initial lever action. The pulling force can reach the two are ends only by diverging over a relatively wide angle from the single anchoring rivet.

In the present invention, efficient distribution of the pulling force is accomplished not only by providing two laterally spaced points of anchorage of the pull tab to the tear panel but also by placing the two rivets closer than usual to the score line and relatively close to the two ends of the arc of initially severed sheet metal. With the tear panel stiffened by the attachment of the pull tab thereto at laterally spaced points and with the two points of attachment relatively close to the score line, the pulling force is distributed radially from both of the points of attachment and is effective not only at the end of the initially severed arc but also along the perimeter of the tear strip beyond the two ends of the arc, the pulling force in effect leading the progressive severance of the metal in the two opposite circumferential directions.

The pull tab of the invention is divided by a forward fold into an upper lever portion and a lower folded-under base portion that is riveted directly to the full-sized tear out panel. The lever portion has a rearward operating arm or handle and has a forward working arm extending beyond the fold, the for-ward working arm being of only a fraction of the width of the tab, The tab is pliable at the fold to permit the fold to serve as a hinge by unfolding action.

The first step in manipulating the tab is to swing the handle end of the tab upward and forward thereby to swing the narrow forward working end of the tab downward against the panel to initiate severance of the sheet metal along a narrow are. The tab is then employed as a handle to exert rearward pull on the panel at an upward angle to spread the severance of the metal around the perimeter of the panel.

The invention teaches that vulnerability of the tab to failure at the bend line of the tab may be avoided by two features. The first feature is that the portion of the tab that bends for pivoting the lever is of many times the width of the portion that is not bent. Thus, the unit stress imposed on the bend by the load on the lever is relatively low. The second feature is that the tab is preformed with a bend of a liberal radius.

The features and advantages of the invention may be understood from the following detailed description and the accompanying drawings.

Brief description of the drawings In the drawings, which are to be regarded as merely illustrative:

FIG. 1 is a plan view of a can end incorporating the presently preferred embodiment of the invention;

FIG. 2 is an enlarged plan view of the pull tab shown in FIG. 1;

FIG. 3 is a bottom plan view of the same pull tab;

FIG. 4 is a greatly enlarged longitudinal section of the pull tab taken along the line 44 of FIG. 1;

FIG. 5 is a fragmentary sectional view illustrating the step of manipulating the pull tab to accomplish initial rupture of the metal at the perimeter of the tear panel; and

FIG. 6 is a similar view showing how the pull tab is manipulated to complete the severance of the tear panel.

Description of the preferred embodiment FIG. 1 shows a can lid, generally designated 10, for a can of relatively small diameter, for example, a can of a diameter of 2" or 2%". A full-sized tear panel 12 is defined by a concentric line of scoring 14 and the tear panel is equipped with a pull tab that is generally designated 15.

The pull tab 15 is a sheet metal stamping divided by a fold 16 into a folded-under rearwardly extending base portion 18 and an upper lever or lever portion 20 that is formed with a rearwardly extending ring-shaped handle 22. The lever 20 may be suitably stiffened, for example, by a rolled inner circumferential bead 24 and a rolled outer bead 25, the outer rolled bead encompassing the ring-shaped handle 22 and extending forward towards the fold 16 on opposite sides of the lever. The lever of the pull tab may be further strengthened by a central longitudinal rib 26 that merges with a transverse =rib 28.

The base portion 18 of the pull tab may be directly attached to the tear panel 12 at two laterally spaced points in any suitable manner. In the construction shown, the base portion 18 is attached to the panel 12 by a pair of hollow rivets 30 that are formed out of the material of the tear panel. Since the lever 20 overhangs the base portion 18 the lever is provided with a pair of apertures 32 which register with the holes 33 for the rivets and permit access to the rivets by tooling for staking the rivets.

The sheet metal of the pull tab is lanced and formed to extend the longitudinal rib 29 forward and thus form a hollow nose 34 that extends forward of the fold 16. Since the fold 16 provides the pivot axis for the fulcrum of the lever 20, the nose 24 constitutes an exceedingly short forwardly extending working arm of the lever. It is also to be noted that the width of the tab that is involved in the fold 16 is a large portion of the width of the tab and is many times wider than the nose 34 that is not involved in the fold. Consequently, the action of the lever creates only low unit stress on the tab in the region of the fold. As shown in FIG. 4 the nose 24 is initially spaced appreciably above the surface of the tear panel 12 to permit the lever to be swung upward through a preliminary angle before the nose makes contact with the tear panel adjacent the score line 14.

FIG. 5 shows the inward flexure of a narrow portion of the tear panel that occurs when the lever is swung upward and forward suificiently to cause initial rupture of the sheet metal at the score line 14. The initial severance along the score line spreads in both directions from the nose 14 for a few degrees but only a minor portion of the tear panel is initially bent inward and the sheet metal is bent inward through only a small angle. Thus the invention reduces the previously discussed objectionable paddle action to insignificance.

After initial rupture of the sheet metal is accomplished in this manner, the tab 15 is employed as a handle to pull upward on the panel 12 to complete the severance of the panel on the can lid. FIG. 6 illustrates an early stage in this final step in the severance of the panel.

It is to be noted in FIG. 6 that the pulling force is exerted upward to a liberal angle relative to the plane of the can lid. It is apparent that with the pulling force tending to lift the tear panel away from the can lid, the pulling force is highly effective to stress the metal in shear to extend the severance beyond the initial arc as the severance progresses in the two opposite circumferential directions. The shearingcomponent increases because the direction of severance progressively approaches parallel relation to the direction of the pulling force that is applied to the tab.

My specific detail description of the presently preferred practice of the invention will suggest various changes,

substitutions and other departures from my disclosure within the spirit and scope of the appended claims.

I claim: 1. In a can top weakened along a line defining a tearout panel with a tab connected to the panel for manual severance of the panel,

the improvement comprising: said tab being divided by a fold into an upper lever portion and a lower folded-under base portion that is directly connected to the panel, 1

said lever portion having a rearward handle end and a forward working end with the working end ertending beyond the fold and overlying the panel near said line,

the material of the tab at said fold being pliable to serve by unfolding action as a hinge between the two tab portions to permit the panel to be severed in two steps, first, by manualy swinging the lever portion upward and forward to bring the working end of the lever portion downward against the panel adjacent said line to depress a marginal portion of the panel along a bend line forward of the base portion of the tab to initiate severance of the panel and, second, by pulling the lever portion rearward with the tab at least partially unfolded to pull on the partialy severed panel to continue the severance of the panel.

2. An improvement as set forth in claim 1 in which the lever portion of the tab is stiffened against flexure.

3. An improvement as set forth in claim 1 in which the tab is made of pliable sheet material and the lever portion of the tab is offset for stiffness.

4. An improvement as set forth in claim 1 in which the fold of the tab is curved to a radius substantialy greater than the thickness of the material of the tab to unfold with low unit stressing of the material.

5. An improvement as set forth in claim 1 in which the working end of the lever portion is initially spaced substantially above the panel whereby the lever portion swings through a corresponding are before the working end of the lever portion encounters the panel.

6. An improvement as set forth in claim 1 in which the lever portion is apertured to permit means to be inserted therethrough for the purpose of attaching the base portion of the tab to the panel.

7. An improvement as set forth in claim 1 in which the base portion of the tab is attached to the panel at a plurality of spaced points to prevent rotation of the tab relative to the panel.

8. In a can top weakened along a line defining a tearout panel with a tab connected to the panel for manual severance of the panel,

the improvement comprising:

said tab being divided by a fold into an upper lever portion and a lower fold-under base portion, said base portion being attached directly to the panel, said lever portion having a rearward handle end,

a central part of said fold being apertured to form a tongue and said tongue being positioned to form a forward working end of the lever portion,

said working end of the lever overhanging the panel forward from the fold,

the material of the tab at said fold being pliable to serve by unfolding action as a hinge between the two tab portions to permit the panel to be severed in two steps, first, by manually swinging the lever portion upward, and forward to bring the working end of the lever portion downward against the panel adjacent said line to depress a marginal portion of the panel along a bend line forward of the base portion of the tab to initiate severance of the panel and, second, by pulling the lever portion rear-ward with the tab at least partially unfolded to pull on the partially severed panel to continue the severance of the panel.

9. An improvement as set forth in claim 8 in which said working end of the lever portion is curved in cross section for stiffness.

10. An improvement as set forth in claim 9 in which the underside of said working end of the lever portion is concave, the working end being in the form of a rounded nose.

11. An improvement as set forth in claim 8 in which the width of the working end of the lever is relatively narrow, the width of the tab at the fold being multiple times the width of the working end of the lever.

12. An improvement as set forth in claim 8 in whi h said lever portion has an upward ofiset in the form of a central longitudinal stiffening rib and said working end of the lever portion is the forward end of the rib.

13. An improvement as set forth in claim 11 in which said base portion is attached to the panel by two rivet elements spaced apart laterally of the tab and in which said lever portion has apertures on opposite sides of said rib 5 to admit tooling for staking the rivet elements.

References Cited UNITED STATES PATENTS 2,085,200 6/1937 Livingstrom 22048 3,322,296 5/ 1967 Khoury 220-48 FOREIGN PATENTS 752,696 2/1967 Canada.

THERON E. CONDON, Primary Examiner.

G. T. HALL, Assistant Examiner.