US3374920A - Container with easily opened segment - Google Patents

Description

March 26, 1968 w. M. PERRY CONTAINER WI TH EASILY OPENED SEGMENT Filed Dec. 1, 1965 FIG.

FIG.6

FIG.8

INVYEN'IQ'ORQ WALT ER M PERRY.

ATTORNEY FIG.|O

United States Patent 3,374,920 CONTAINER WITH EASILY OPENED SEGMENT Walter M. Perry, 76 Locust Hill Road, Darien, Conn. 06820 Filed Dec. 1, 1965, Ser. No. 510,742 14 Claims. (Cl. 220--s4 ABSTRACT OF THE DISCLOSURE A can,.typically for a beverage, has an end, usually aluminum, with an openable segment defined by score lines, and a lift tab disposed transversely of the segment. The tab may be widened and fastened to the segment by two spaced rivets preferably integral with the segment. One rivet is tight, and the other preferably has clearance to permit partial raising of the lift tab before taking effect, in order not to interfere with initial rupture of the segment at the first fastening means when starting to open the can. The score line grooves are formed in the top surface of the can end near the lift tab, and are formed in the bottom surface at parts of the segment remote from the lift tab. A single rivet may be used, preferably triangular, with its apex directed toward the transverse lift tab. These improvements reduce the force needed to open the container.

This invention relates to containers, especially metal cans, and more particularly to such containers arranged for easy opening without the need of a separate opening device.

The invention applies to a so-called self-opening container which has a removable segment defined by a score line, and to which is attached a lifting tab such that the container can be opened without requiring an additional tool or key or other device. The improvement can be applied to containers used for any purpose, but it is particularly well adapted to those used for carbonated beverages.

During transportation and handling very high pressures frequently are built up in containers holding such beverages. For that reason they are made of relatively heavy gauge material, and the score line cannot be made very deep without danger of bursting. The tops are generally made of aluminum because it may be thicker than steel, and easier to score accurately, and with less tool wear, and also because the integral rivet to hold the tab can be drawn more readily from the material of the top.

A common type of container end is circular and has a wedge shaped segment starting at the center. A tab is attached to the inner end of the segment by an integral rivet. The tab has projecting legs to provide leverage to break open the inner end of the segment by a straight lift, with the metal below the score failing in shear.

The force needed to open this type of container is too large, especially since its use has been extended to soft drinks, so that the containers should be openable by children. The length of the tab is limited to say /3", because of the size of the most popular 12 ounce cans, which have a diameter of only 2 /2". The initial force on the end of the tab to open this type is say seven pounds. As soon as the inner end of the segment breaks out, an even greater force of say eight pounds is needed to tear the segment out toward the outer end. The metal bends at right angles as the tear progresses, and both edges have to be sheared simultaneously, which accounts for the large force required. At the outer end of the segment an I opening. r

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The general object of the present invention is to improve this class of container requiring no can opener or key or other such tool. A more particular object is to greatly reduce the force required to open the container after it has first been popped open, the said force being reduced to less than three pounds, which is only a fraction of the force usually required.

To accomplish the foregoing general objects and other more specific objects which will hereinafter appear, my invention resides in the containers with improved openable segments, as are hereinafter more particularly described in the following specification. Thespecification is accompanied by a drawing in which:

FIG. 1 is a partially sectioned elevation of a container embodying features of the present invention;

FIG. 2 is a plan view of the container;

FIG. 3 is a fragmentary section drawn to enlarged scale and taken on the line 33 of FIG. 2;

FIG. 4 is a fragmentary section taken on the line 44 of FIG. 2;

FIG. 5 is a plan view showing a modified container having an enlarged segment to provide a larger size opening;

FIG. 6 is a plan view of a container having reversed score lines;

FIG. 7 is a fragmentary section taken on the line 7-7 of FIG. 6 and showing the reversed score lines;

FIG. 8 is a plan view of a container having a generally triangular shaped rivet;

FIG. 9 is a plan view of a container having a triangular rivet combined with a second rivet and having reversed score lines; and

FIG. 10 is a section taken on the line 1010 of FIG. 9, but with the lift tab raised.

Referring to FIG. 1 of the drawing, the container may be generally conventional, and as here illustrated has a cylindrical body 12 and a circular bottom 14 secured thereto by means of a conventional end seam 16. The body 12 may itself have a vertical side seam, not shown. The top is closed by a metal end 18, secured to the body 12 :by means of an end seam 20 which may be conventional. The can end 18 is made of metal, usually but not necessarily aluminum, and it has an openable segment 22 (FIG. 2) defined by a score line, here represented by dotted lines 24, 36, and 42.

There is a lift tab 26 which may be made of aluminum or of a stiffer metal, for example tinned steel, and which may have a folded edge 28 to stiffen the same. In the present case in which the lift tab is widened, there is also a longitudinal rib or inverted channel 30 to help additionally stiffen the same.

The inner end of segment 22 has an upwardly projecting rivet 32 which secures the lift tab 26 to the segment. This rivet usually is integral with the can end 18, it being formed by a drawing operation which provides an upwardly projecting inverted cup over which a mating hole in tab 16 is applied. The top of the cup then is flattened downward, as shown at 32 in FIG. 3, to rivet the tab 26 to the segment 22, without losing the continuity of the sealed can end 18.

The can body 12 and the bottom end 14 often are made of tinned steel, and in some cases are made of aluminum. Other materials may be used, the present invention being directed primarily to the openable top end 18. In current practice this is made of aluminum, for reasons-previously pointed out, but another material may be used if suited for the necessary drawing, scoring, and eventual shearing or opening operations.

By reference to FIGS. 2 and 4 it will be seen that in addition to the center rivet 32, the present can end has a second rivet 34 spaced from the first rivet in a direction generally lengthwise of the segment, and preferably nearer to open the can. This keeps the break-open force at a minimum.

If both rivets were tight, the length of score line to be initially broken would be increased, whereas with the I present construction it is not. When the tab is first raised its force is all on the first rivet 32, and the initial rupture is in the score line 36 at a point directly under the tab 26 and then around the inner end 38 of the segment. Further raising of the tab transmits a lift to the second rivet 34 and the rupture continues along score line 36 to the corner 40, and then across the end 42 to the corner 44. This rupture is progressive because of the design of a rib 46, which only moderately sti'ifens the segment, and allows some bending. The rib 46 has a transverse extension 48 at its outer end, which turns in a direction away from the lift tab 26. The rib is die formed in the material of the segment, and starts close to rivet 34 so that the rivet can exert force through the rib. The rib can be depressed as shown, or raised.

By the time the rupture has reached corner 44, the segment is turned up ninety degrees on its edge at score line 24, and it breaks off completely along this line. The force needed is surprisingly small. The reasons the force needed to complete opening from 38 to 46 to 42 is so low are first, because the rib is weak enough to permit the segment to bend just enough so that the tearing is progressive; second, because the segment is hinging around the line 24 from inner rivet 32 to the corner 44, and the tab has a mechanical advantage or leverage based on the ratio of the distance from line 24 to the tip of the lift tab, to the distance "from line 24 to line 36, or about three or four to one; and third, because only one shear line is being torn at once.

Referring to FIG. 3, attention is directed to the fact that the tip 50 of the lift tab 26 is raised to prevent this part of the tab from opposing fiexure of the segment. When the lift tab is raised rivet 32 cocks and tries to tilt or cock the segment between the score lines 36 and 24. The metal is raised at 36, and this introduces 'a bending stress in the metal directly under the score line 36. Because of the sharpness of the crease there is a concentration of stress, this being a phenomenon which is well known in engineering. Differently expressed, any sharp corner is an incipient cause of failure.

The bending stress is added to a straight shear stress caused by the vertical lift of the tab, and initial rupture takes place at the score line 36. There is also a bending force at the score line 24, but in this case the maximum stress is on the bottom surface which is smooth and therefore not subject to stress concentration. (For this reason an underside score at 24 has an advantage, as is explained later.)

Reverting to FIG. 4, the clearance space shown under the head of the second rivet 34 permits the lift tab to lift freely a certain distance before it exerts a lift and/ or bending force on the rivet 34 and the open-able segment 22. For non-pressure cans the two rivets 32 and 34 might both be tight, because in that case, the material may be thinner, or the score line grooves may be deeper. For either or both reasons the segment then would be more easily openable, thus making it feasible to initially shear a greater length of score line as would happen if both rivets were tight.

The present construction makes it feasible to enlarge the segment and to thereby provide a larger size opening in the can end. This is illustrated in FIG. 5, in which an enlarged segment 52 has va lift tab 54 secured thereto by means of two rivets, the inner or center rivet 56 being tight, and the second rivet 58 being loose, and preferably being disposed near the score line 60 and remote from the score line 62. The widened lift tab 54 may be like that previously described, it being stiffened by a protective rolled edge 64, and by a longitudinal bead or rib 66. The segment 52 is moderately stiffened by means of an inverted channel or upwardly struck rib 68 having a transverse extension 70 which generally follows the contour of the end 72 of the segment. The segment should not be rigid because that would require shearing too much length of score line at one time. It should not be too flexible because then a direct upward pull would be needed. It therefore should afford some gradual or limited bend as it is being opened.

It will be understood that with this construction the initial break-away of the metal around rivet 56 requires only the usual force; that the second or loose rivet 58 then comes into play with continued easy break-away along the score line 60; and that the shearing action then continues progressively along the end line 72, this being aided by the stiffening rib 70, until finally the segment hinges upward around the score line 62, and breaks off at that score line.

I have found that thisfinal break-away may be facilitated by using at the farther side of the segment a bottom score line instead of a top score line. This is illustrated in FIGS. 6 and 7, in which the openable segment is defined by side score lines 82 and 84, and an end score line 86. The lift tab 88 is shown secured to the openable segment 80 by means of a single rivet 90. This rivet may be located as usual at the center of the can, or if desired, it may be shifted radially outward somewhat, as here shown. The lift tab 88 is stiffened by a rolled edge 92, and the openable segment 80 is stiffened by a raised rib 94, preferably having a transverse extension 96 at its outer end. By referring to FIG. 7, it will be seen that the score line 82 is in the top surface of the can end 98, while the score line 84 is in the bottom surface of the can end. The tilt which results when lift tab 88 is raised then concentrates maximum stress in the score line grooves.

Reverting to FIG. 6, the score lines as viewed in plan may intersect and be extended slightly beyond one another, as will be seen at 100 and 102. This has the advantage that the dies for scoring the top and bottom surfaces of the can end do not have to be in perfect alignment or registration. Some error or tolerance may be afforded without interfering with the desired easy opening of the segment. The score lines must not be too deep at the intersection.

Still another feature may be described with reference to FIG. 8 of the drawing. This shows the use of a rivet which is generally triangular instead of circular. This concentrates the breakout force at the point or apex 112 of the rivet. Moreover, the are 114 of the score line 116 is deflected outwardly around the apex 112, and then is more easily sheared than would be the case around a round rivet. The projection at 114 is flexible and provides maximum bending stress. Thus the initial breakaway is facilitated, compared to the use of a conventional round rivet. In FIG. 8 the lift tab 118 and the segment 120 may be conventional, although the segment preferably is provided with a stiffening channel 123, for reasons previously described. The end score line 117 maybe a reverse or bottom score line.

The various features of the invention may be combined advantageously. FIGS. 9 and 10 show a can end 122 which combines the double fastener, the triangular rivet, and the reversed score lines, all previously described. Considered more specifically, the widened lift tab 124 is like that described in connection with FIGS. 2 and 5. Its widened inner end is secured to the openable segment 126 by means of a tight rivet 128 and a second loose rivet 130. The tight rivet 123 is generally triangular instead of circular, and the score line 132 is a top groove which is deflected outwardly around the apex of the rivet, as is shown at 134. The remote score line 136 is a bottom groove, and the ends of the score lines may intersect and extend somewhat beyond their intersections, as is shown at 138 and 140. As before, the openable segment 126 is preferably stiffened somewhat by means of a rib 142, having a transverse extension 144 at its outer end.

In the present case it may be noted that the score line 136 has a change of direction at 146. This greatly assists break-off of the segment 126 along the line 136 from the points 138 to 140. Turning or hinging the segment on a bent line instead of a straight line creates additional forces which are not present when hinging the segment on a straight line, and this assists the desired breakaway. Here again the final separation is aided by locating the score line 136 on the bottom, this being shown in FIG. 10, in which score line 134 is in the top surface and score line 136 is in the bottom surface of the can end 122. In FIG. the lift tab 124 is shown raised somewhat, with consequent tilting of the segment 126. This opens the grooves, or bends the thinned metal with concentrated stress under the grooves, and with consequent easy rupture or shear of the thinned metal.

The bent score line shown at 136 in FIG. 9 may also be used at 132. This is also shown in FIG. 6 at 82 and 84. Such a bent score line may be used also in the segments of FIGS. 2, 5, and 8, instead of the straight score lines there shown.

Referring again to FIG. 8, the reverse score line 117 at the end of the segment in certain circumstances facilitates breaking of the metal by upward bending along this line, as compared with top scoring, because of the stress concentration in the score as previously discussed. It is advantageous for both single and double rivet construction in case the two side scores yield first, and a direct pull is then exerted on the end score. This may happen with the double rivet if the side score lines are uneven through fautly manufacture, or if the operator exerts the "wrong motion in tearing out the segment.

Where the two score lines cross, as at 100 in FIG. 6, the depth of cut on each line is tapered off near the ends, so that at the crossing point each score is correspondingly more shallow. In other words, the metal should not be excessively weakened at the intersection.

It is believed that the construction and method of use of my improved container end, as well as the advantages thereof, will be apparent from the foregoing detailed description. In a typical case the initial breakout force is say four to five pounds, and the opening force thereafter is reduced to say three pounds or less, instead of being greatly increased, as heretofore. It will also be apparent that while I have shown and described my invention in several preferred forms, changes may be made in the structures shown without departing from the scope of the invention, as sought to be defined in the following claims.

In the claims the term segment means a removable area of any shape and it may be located in the top or wall of the container. The term score line refers to a weakened line formed by thinning the material. The term container en applies to the openable wall even if large relative to the height of the container, as in the case of a flat rectangular can.

I claim:

1. A container end having an openable segment defined by score lines, and a lift ta-b, said segment having near one end a first means fastening said lift tab thereto, said tab being disposed transversely of said segment and being widened at its fastened end to receive a second fastening means, said second fastening means being spaced from said first fastening means.

2. A container end as defined in claim 1, in which the first fastening means is tight, and in which the second fastening means has clearance relative to the lift tab, said clearance being such as to permit partial raising of the lift tab before taking effect, in order not to interfere with initial rupture at the first fastening means when starting to open the can.

3. A container end as defined in claim 2, in which each fastening means is an integral upwardly projecting rivet, the head of the second rivet being located somewhat above the tab with clearance therebetween.

4. A container end as defined in claim 2, in which the openable segment is moderately stiffened by means of a rib formed therein.

5. A container end as defined in claim 1, in which each fastening means is an integral upwardly projecting rivet.

6. A container end as defined in claim 1, in which the openable segment is moderately stiffened by means of a rib formed therein.

7. A container end as defined in claim 1, in which the second fastening means is located near the score line groove that is on the same side as the lift tab.

8. A container end as defined in claim 1, in which the score line groove on the side of the segment nearer the free end of the lift tab is formed in the top surface of the container end, and in which the score line groove on the side of the segment remote from the lift tab is formed in the bottom surface of the container end.

9. A container end as defined in claim 1, in which the tion, with the apex of the triangle disposed toward the lift tab, and in which the score line defining the segment is deflected outwardly around the said apex, thereby minimizing the tab lifting force needed to initiate breakaway or rupture.

10. A container end having an openable segment defined by score lines, and a lift tab disposed transversely of the segment, said segment having at one end an integral upwardly projecting rivet securing said lift tab thereto, said rivet being generally triangular in configuration with its apex directed toward the lift tab, and the score line defining the openable segment being deflected outwardly around the said apex of the rivet, thereby minimizing the lifting force needed to initiate breakaway or rupture, the score line groove on the side of the segment nearer the free end of the lift tab being formed in the top surface of the container end, and the score line groove on the side of the openable segment remote from the lift tab being formed in the bottom surface of the container end.

11. A container end as defined in claim 10 in which the openable segment is moderately stiffened by means of a stiffening bead formed lengthwise thereof, and which at its outer end turns transversely in a direction away from the lift tab.

12. A container end having an openable segment defined by score lines, and a lift tab, said segment having near one end an integral upwardly projecting rivet securing said lift tab thereto, the score line grove at one side of the openable segment being formed in the top surface of the container end, and the score line groove in the opposite side of the openable segment being formed in the bottom surface of the container end.

13. A container end as defined in claim 12, in which the lift tab is disposed transversely of the openable segment, and in which the score line roove on the side nearer the free end of the lift tab is formed in the top surface of the container end, and the score line groove that is more remote from the lift tab is formed in the bottom surface of the container end.

14. A container end as defined in claim 12, in which the score line groove at the end of the segment which is farthest from the tab is on the underside of the surface wall.

References Cited UNITED STATES PATENTS 3,225,957 12/1965 Huth 22054 3,285,467 11/1966 Moran 220-54 THERON E. CONDON, Primary Examiner.

G. T. HALL, Assistant Examiner.

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