US 3779417 A
The invention concerns a gated can lid having a tab therein defined by a score line, to be pushed into the can as the metal neck between the tab and the lid at the score line is severed. The tab is dished upwardly to a convex form which may be flexed, by pushing, to a downward concave form with the periphery of the tab hinging about the metal neck at the score line as the flexing occurs. A disruption, such as a crease, is formed across the score line at a selected point to cause a positive rupture of the metal neck at the score line as the tab is pushed from the convex to the convave position, such rupture initiating and facilitating the tearing away of the tab from the can lid as the tab is then pushed inwardly into the can.
Claims available in
Description (OCR text may contain errors)
United States Patent [1 1 Klein Dec. 18, 1973 FLEX TAB FOR A GATED CAN LID  Inventor: Gerald B. Klein, 1345] Stuart Ct.,
Broomfield, Colo. 80020  Filed: Feb. 14, 1972 ] Appl. No.: 225,920
 Int. Cl t 865d 17/00  Field of Search 220/27, 48, 47; 222/541  References Cited UNITED STATES PATENTS 3,227,304 H1966 Asbury 220/48 2,26l,ll7 ll/l94l Jack 3,334,775 8/]967 Klein et al. 220/48 Primary ExaminerGeorge T. Hall Attorney-Frank C. Lowe  ABSTRACT The invention concerns a gated can lid having a tab therein defined by a score line, to be pushed into the can as the metal neck between the tab and the lid at the score line is severed. The tab is dished upwardly to a convex form which may be flexed, by pushing, to a downward concave form with the periphery of the tab hinging about the metal neck at the score line as the flexing occurs. A disruption, such as a crease, is formed across the score line at a selected point to cause a positive rupture of the metal neck at the score line as the tab is pushed from the convex to the convave position, such rupture initiating and facilitating the tearing away of the tab from the can lid as the tab is then pushed inwardly into the can.
15 Claims, 25 Drawing Figures PATENTEB DEC 1 81975 SHEET 1 [1F 3 PAIENIEU DEC] 8 ms SHEET 2 OF 3 Fig/3 Fig.l8
FLEX TAB FOR A GATED CAN LID This invention relates to gated can lids, and more particularly to can lids which are gated with a preformed tab in the lid which will be pushed downwardly and into the can when the can is opened.
The use of pre-formed tabs in the lids of beverage cans, as gates to be torn therefrom, has become so widespread as to be almost universal. The most common type uses a scored tab in the can lid combined with a ringed pull to permit the tab to be easily torn away from the can lid. While such a tear-off tab for beverage cans has achieved almost universal popularity, a problem is being created by the large number of tabs being thrown away in an indiscriminate manner to the point where they are creating not only anuisance, but also a hazard. The tabs are small metallic curls with very sharp, ragged edges. Such a small metallic curl in the sands of a beach is not easily noticed and can cause a severe cut should a barefoot individual step upon it. This problem has become so serious, in fact, that the State of Oregon has already passed legislation prohibiting the use of pull-out tabs on beverage cans and other states are contemplating such legislation.
It has been proposed to solve this problem by the use of a gated can lid, wherein the tab is pushed into the can, with the tab being hinged to the lid so it will remain therein, in a safe, out-of-theway location. In its general form, the tab may be an elongated member, integral with the lid, and the tab is defined by score marks at one end and at its sides where it is to be severed from the lid. No score mark is necessary at the other end where it hinges to the can lid. U.S. Pat. Nos. 3,246,791, 3,227,304, 3,334,775 and 3,555,058 are exemplary of such a construction.
The present invention concerns improvements in a push-in tab to more easily break the tab away from the can lid at the score marks defining the gate. In prior concepts, the tab was simply pushed into the can. Reinforcing means could be used to hold the can rigid, and a pointed tab could be used, if necessary, to commence tearing the score mark. This score mark, cut into the lid, will leave a thin, metal bridge or neck connecting the tab and the lid. This thin neck, once ruptured, will easily tear, bu otherwise, it can resist substantial pulling or shear forces. Accordingly, difficulty has been experienced in opening push-in tabs and the present invention was conceived and developed with such considerations in view, and comprises, in essence, a modification of the tab to a slightly dished structure adapted to flex from a convex to a concave form in a manner analogous to the undersurface of an oil can, an effect which is commonly referred to as an oil can action. This action, combined with irregularities in the surface of the tab at the score line can create stress concentrations at the score line which will easily rupture the neck at the score line.
It follows that an object of the invention is to provide a novel and improved push-in tab in the lid of a beverage can which may be opened by pressing against the gate with a moderate finger or thumb pressure.
Another object of the invention is to provide, in a push-in tab in the lid of the can having the outline of the tab defined by a score mark, a novel and improved means to rupture the score mark to permit the tab to be first ruptured to relieve internal pressure, if necessary, and then to be easily torn from the lid as it is pushed into the can.
Another object of the invention is to provide a novel and improved means for opening a can having a pushin tab in the lid thereof, which does not require special components mounted upon the lid or tab to facilitate opening the can.
Other objects of the invention are to provide, in a push-in tab integral with the lid of a can, a simple, economical arrangement of structural components to facilitate severing the gate from the can with only a moderate degree of force, which is positive and reliable in its operation and which requires a minimal space above the surface of the lid and wont interfere with packaging of nested lids nor the feeding and indexing of lids in a can closing machine, nor with the stacking of cans upon each other when they are packaged.
With the foregoing and other objects in view, my present invention comprises certain constructions, combinations and arrangements of parts and elements as hereinafter described, defined in the appended claims, and illustrated in preferred embodiment in the accompanying drawing, in which:
FIG. 1 is an isometric view of the upper portion of a can having a push tab formed in the lid thereof, modifled according to the principles of the present invention.
FIG. 2 is a plan view of the can lid illustrated at FIG. l, with dotted lines indicating the location of the score mark at the underside of the tab where the tab is torn from the can lid when it is pushed open.
FIG. 3 is a longitudinal sectional view of the top portion of the can, as taken from the indicated line 3-3 at FIG. 2, but on an enlarged scale and with broken lines showing the manner in which the tab flexes and opens when pressed by an individuals thumb.
FIGS. 4, 5 and 6 are fragmentary sectional details, as taken from the respective indicated lines 44, 55 and 6--6 at FIG. 3.
FIG. 7 is an enlarged fragmentary view of a portion of the underside of the can lid and of the tab formed therein.
FIG. 8 is a fragmentary sectional view similar to a portion of the showing at FIG. 3, but on a further enlarged scale and indicated in borken lines, the movement of the edge of the tab when it breaks loose from the can lid.
FIG. 9 is an isometric view of a portion of the tab per se, as it would appear when torn from the can lid.
FIG. 10 is a plan view of a can lid similar to that illustrated at FIG. 2, but showing a modified embodiment of the invention.
FIGS. 11 and 12 are fragmentary sectional details as taken from the respectively indicated lines Ill-11, 12]l2 at FIG. 10, but on an enlarged scale.
FIGS. 13 and M- are fragmentary sectional details as taken from the respectively indicated lines 13-13 and 114-141 at FIG. ill, but on a further enlarged scale.
FIG. 15 is an enlarged fragmentary bottom view of a portion of the can lid shown at FIG. 10 and of the tab therein, showing specifically, the score line.
FIG. 16 is an isometric view of the front portion of the tab per se, as it would appear when torn from the can lid.
FIG. 17 is a fragmentary sectional detail showing a portion of the lid and tab as illustrated at FIG. 14, but on a further enlarged scale and with the edge of the tab flexed to better illustrate the manner in which the tab commences to tear away from the lid when flexed.
FIG. 18 is an isometric view of the front portion of the tab per se, similar to the showing at FIG. 16, but illustrating another manner of cutting the score line between the tab and the can.
FIG. 19 is a plan view of a can lid similar to that illustrated at FIG. 2, showing a second modified embodiment of the invention.
FIGS. 20 and 21 are fragmentary sectional details, as taken from the respective indicated lines 2020 and 2l21 at FIG. 19, but on an enlarged scale.
FIG. 22 is a longitudinal sectional detail as taken from the indicated line 2222 at FIG. 19, but on an enlarged scale and with broken lines indicated the manner in which the tab shifts when it is being flexed to open the can.
FIG. 23 is a plan view of a can lid similar to that indicated at FIG. 19, but showing a third modified embodiment of the invention.
FIG. 24 is a fragmentary sectional detail as taken from the indicated line 24--24 at FIG. 23, but on an enlarged scale.
FIG. 25 is a fragmentary sectional detail similar to a portion of FIG. 24, but showing a further modification of the invention.
Referring now particularly to the drawing, FIG. 1 illustrates the top portion of a metal can C having a cylindrical wall closed by circular lid L. The lid is joined with the top edge of the wall by a conventional, folded, double-seamed rim R and this rim R upstands a short distance from the surface of the lid. The bottom of the can is closed by a similar lower lid, not shown, or, if the can is of drawn aluminum, the bottom is integral with the cylindrical wall.
In accordance with the present invention, the lid L is gated with a tab T which may assume various forms at the option of the manufacturer. For example, the tab T shown at FIGS. 1 9 and the tab T shown at FIGS. 10 18 are elongated and are fitted underneath an oval aperture A in the lid, while the tab T" as shown at FIG. 19 is fitted underneath a circular aperture A. The aperture A, shown at FIGS. 1 18, is generally longitudinally symmetrical. It is provided with a narrower, circular venting end 26 near the center of the lid and a wider circular pouring edge 27 near the rim R. Extended sections 28 lie between the venting end and pouring edge as illustrated. The tab structure itself may also be formed in the plane of the lid by merely providing a score line at the underside, or top side, of the lid defining the area of the tab, as indicated as tab T' at FIGS. 23 25 and hereinafter further described.
In the preferred arrangement, the tabs T and T, shown at FIGS. 1 18, are below and underneath the aperture A and are secured to their respective lids through a connecting underfold rim 30 about the aperture A. The underfold rim 30 turns underneath the lid, to lie between a first 180 aperture fold 31, defining the edge of the aperture A, and a second 180 bottom fold 32, which merges into the tab T, or T. This construction and its advantages are described in the US. Pat. No. 3,334,775.
When the underfold rim 30 is used, the tab T, or T, is larger than the aperture A and its boundaries are defined by a score line 33 cut adjacent to or at the outward bottom fold 32 so that the edges of the tab abut against the undersurface of the underfold rim and beneath the lid surface as in the manner indicated by the broken line at FIG. 2, the tab being larger than its aperture. It is to be noted that the score line 33 is extended about the pouring end 27 and the extended sections 28 of the aperture, but it need not extend about vent end 26. The unscored portion between the tab and the lid at this vent end 26 will provide a hinge area 34 about which the lid bends when it is pushed downwardly and into the can as partially indicated in broken lines at FIG. 3.
The manufacture of the can lids L having tabs T, T or T" beneath the respective apertures A or A" will follow a conventional procedure which need not be described in detail. It is to be noted, however, that the machinery which will form the aperture A, the tab T, the underfold rim 30 and the score line 33 will do so with a great degree of precision so that the tab remains integral with the lid with a small metal neck 35 at the score line joining the tab to the lid. This neck 35 will be very thin, and its actual thickness will depend upon whether the lid is of steel or is of aluminum.
To open the can by pushing the tab into the can, the metal at the neck 35 must be severed as by tearing. It was found, however, that this metal neck 35 must first be ruptured at some point before tearing could commence for it was observed that this thin segment of metal could resist a substantial tension or shear force even though it would easily tear once it was ruptured. Unless a rupture occurred, the force required to push in the tab could be so large as to prevent anyone from opening the can by finger pressure alone. Thus, the problem of effectively rupturing the metal neck 35 formed at the score line before the tab could be pushed into the can was found to be an important consideration in the construction of a push-in tab for a can lid.
Referring first to FIGS. 1 9, the tab T is dished to provide a dome 36 which will extend a short distance above the top surface of the can lid, but not to such an extent as to interfere with the nesting of one lid against another lid as when they are ready for shipment, or the feeding of lids into a can closing machine. FIG. 3 illustrates a dome as extending only part way to the top of the rim and such an extent is exemplary of a reasonable height limitation. Actually, it is to be noted that the height of the dome 36 may be somewhat exaggerated in the drawing for purposes of better illustration. It is to be emphasized that the proportions of the dome 36 must be such that the dome can be easily flexed by the elastic properties of the tab from the convex position, illustrated in full lines at FIG. 3, to a concave position as illustrated in dotted lines. The actual height of the dome in the tab to produce this flexing can be determined by simple experiments and will depend upon the metal forming the lid.
This dome 36 is symmetrical about a longitudinal axis, but is preferably asymmetrical about a transverse axis. Thus, a peak 37 may be located near the pouring edge 27 so that a steeper portion 38 of this dome extends downwardly from the peak and to the pouring end 27 of the aperture A while a much flatter portion 39 extends from the peak to the venting end 26 of the aperture. Accordingly, when the dome is flexed from the convex to a concave position, the steeper portion f the dome adjacent to the pouring edge will produce a greater angular movement with respect to its connection with the lid. This angular movement will naturally hinge about the thin, comparatively-weak metal neck 35 to facilitate its rupture as will be described.
The dome 36 must not form a rigid arched structure which is so proportioned as to prevent the tab T from flexing from the convex to a concave position. Such may occur at the reach of the tab alongside the side edges 28 which may be transversely arched in such a manner as to be rigid. Thus, simple longitudinal corrugations 40 are formed in the dome 36 alongside the straight sections 23 of the aperture A to permit the done to flex. Also, the corrugations 40 may extend about the pouring end of the dome and merge into the surface of the tab adjacent to the hinge area 34. The manner in which such corrugations are formed can be varied considerably, and simple tests will produce an arrangement which will provide easy lateral flexing of the tab as it is pushed from the convex to a concave position.
The convex to concave flexing action of the domed tab is ordinarily adequate to rupture the neck 35 at the score line 33 because the flexing of the tab will be accompanied by a hinging action at the neck 35. However, in the present invention, it is desirable to positively rupture the score line 33 and also, to commence the rupture at a selected point, such as at the pouring end 27 of the aperture. This is assured by forming a surface irregularity in the tab across the score line. Such irregularity may be formed in various ways, such as by a crease or bead. The flexing of the tab will produce a stress concentration at suchan irregularity which will far exceed the strength of the metal neck.
In the construction illustrated at FIGS. 1 9, a simple upward crease 41 is formed at the center of the pouring end 27 of the aperture A. The crease 41 commences at the edge of the underfold rim 30 and extends a short distance into the body of the tab, merging into the tab near the peak of the dome 37 in any suitable manner. This crease in the tab T and in the underfold rim 34) will also extend into a can lid towards the rim R of the lid to produce an upwardly folded dimple 42 at the edge of the aperture.
This crease will shift the alignment of the metal neck 35 out of the flat planar surface of the undersurface of the rim 30 as illustrated at FIG. 9. Accordingly, whenever the convex dome of the tab is concaved by pushing it to produce a flexing action, the tab will hinge about the neck 35, at the score line, as it rotates with respect to the lid.
FIG. 7, a bottom view, shows the score line 33 cut in a portion of the tab and an indication of the crease 411 at the edge of the tab crossing the score line 33, while FIG. 9 shows the tab after it has been severed from the lid. The crease 41 clearly disrupts the score line 33 and neck 35 from a flat plane and it is apparent that any rotation of the tab at the score line, as the tab flexes from the convex position to a concave position, will be accompanied by a pulling and pushing action on the metal neck at this crease All. It is also to be noted that the forming of the aperture fold 30, the tab T and the cutting of the score line 33 will work to harden the metal at the neck 35 to cause it to be comparatively brittle and easily ruptured.
Once such a rupture occurs, the can is opened at the crease and any gas under pressure within the can will be vented. Thereafter, a continued push against the tab will tear the metal neck 35 at the score line 33, and the tab will be pushed into the can to open the aperture A.
The flexing action of concaving the tab will assist in the tearing of the neck at the score line once a rupture is effected at the crease. The tab, in passing from the convex to the concave position during its flexing, will enlarge and lengthen somewhat, as indicated in broken lines b at FIG. 8. This will stress the tab and a substantial portion of the tab will thus be torn free of the lid during the flexing operation.
The tab T, illustrated at FIGS. Ml I8, contemplates the forming of two, side-by-side creases 43 and 44 with a groove 42-5 between them and a double dimple 416 at the edge of the can lid aperture. Otherwise, this tab T is similar to the tab T, using a dome 36 with its peak 37 near the pouring end 27 of the aperture as heretofore described. In this unit, however, it is contemplated that the score line 33 will be disrupted from a circular path about the pouring end of the aperture by a W-shaped offset 47 around the channels formed by the creases 43 and 44 when viewed from the underside of the lid, as best illustrated in FIG. I5. In this manner, the score line 33 will lie in a flat plane with the disruption of the score line and the neck 35' being in a plane paralleling the undersurface of the underfolded rim about the tab T.
It is to be noted that this W-shaped offset will have an inwardly directed point 48 at its center and this point will constitute a rupture point whenever the tab is flexed from a convex to a concave position. The rupture action is illustrated by comparing FIGS. 14 and FIG. 17. The steeper portion 38 of the dome 36 formed in the tab will rotate downwardly from the position shown at FIG. 114 to that shown at FIG. 17. When so r0- tated, the groove portion 45 of the tab T, between the creases 43 and 44, must move downwardly. A fulcrum action occurs at the lower points of the creases, adjacent to the neck and these points bear against the undersurface of the underfold rim 30. At the same time, the center point 48 remains at the rim 30 causing a rupture as at edges 49 of the W-shaped offset, as shown at FIG. 117. It is clearly apparent that the leverage action available will cause the force at the point 48 to be considerable, and the rupture is easy and positive.
FIG. 18 shows a modification of the tab T where the score line 33a is cut before the creases 43 and 44, are formed. The W-shaped offset 5%, resulting from the creases, causes the score line 33a at the disruption to be offset from its normal flat, planar configuration, and the action of this modified construction is essentially the same as that described for the construction illustrated in FIGS. ll '9.
The tab T, illustrated at FIGS. 19 22, is essentially the same as the tab T illustrated at FIGS. ll 9, as heretofore described excepting, that the tab T and aperture A are circular. Preferably, the aperture A" is offset from the center of the lid to define a venting side 26" near the center of the lid and a pouring edge 27 adjacent to the lid rim R. The underfolded rim 30" is circular, but is essentially as described and the score line 33", defining the tab T, is likewise circular and with an unscored portion adjacent to the venting end to form a hinge area 341", if desired.
The tab T" is suitably formed as dome 36" to flex from a convex to a concave position, substantially as heretofore described. Circular corrugations may be formed in this dome to facilitate its flexing and then corrugations may be concentric to give the circular dome a bellows-like appearance, or the corrugations may be offset towards the hinge area as illustrated.
A crease 41" traverses the score line 33" and neck of metal 35" at this score line, preferably at the pouring end 27" as illustrated. The crease disrupts the score line, causing the neck 35 to rupture at this point whenever the tab T" is flexed downwardly as heretofore described in detail.
The underfolded rim 30 becomes important in a push-in tab where an individual may push his finger partway into the can through the aperture A. The tearing of the neck 35 at the score line 33 produces an undesirable sharp edge, and without the rounded, 180 aperture fold 31, an individual will risk a serious cut every time he opens a can. The invention, however, may be used with a tab T' formed in the plane ofa lid L by a simple score line 51, as illustrated at FIGS. 23 25. The tab T may take any form, such as the circular form illustrated, and it may be offset from the center of the can to provide a venting end 52 near the center of the lid and a pouring end 53 near the rim of the lid. The score cut 51, shown in broken lines at FIG. 23, need not extend about a complete circle, but an uncut hinge area 54 may be provided at the hinge end.
A crease may be formed in the lid as heretofore described, or a modified crease 55 may be provided as shown, to extend across a segment of the circular tab T' and intersect the score line at two points as illustrated. As heretofore described, this tab T is formed as a convex dome 56 with suitable corrugations 57 to permit it to flex from the convex to a concave position as heretofore described. The disruptions of lhe neck 58 of metal between the lid line and the tab, caused by the crease, will also cause rupture of the tab so that the tab can be easily torn from the lid as it is pushed downwardly into the can.
I have described several various embodiments of the invention. Various other modifications to the arrangements are possible. For example, the creases 41, 43, 44 and 55 are described as being upward, but they may also function effectively if they are also downwardly as crease 59 illustrated at FIG. 25. Yet other modifications of the tab, which are not shown but which are within the scope of the invention, are possible. Hence, I desire that my protection be limited, not by the constructions illustrated and described, but only by the scope of the appended claims.
1. In a can lid having a push-in tab integral with the lid and with the outline of the tab being defined by a score line cutting partway through the lid to leave a narrow, severable neck at a surface of the can lid, interconnecting the tab and the lid, the improvement wherein:
said tab is a flexible dome convexing upwardly from the surface of the lid but adapted to be pushed downwardly to concave below the surface of the lid, whereby the flexing of the dome from the convex to the concave position produces a hinging action about the said severable neck to facilitate severance thereof and separation of the tab from the lid.
2. In the organization defined in claim 1, wherein:
corrugations are formed in the dome to facilitate flexing the same from a convex to a concave position.
3. In the organization defined in claim 1, including:
an abrupt distortion in the alignment of the score line and the metal neck, whereby the aforesaid hinging action responsive to flexing of the tab effects a rupture of the neck at the point of disruption. 4. In the organization defined in claim 3, wherein: the distortion in the alignment of the score line comprises a W-shaped irregularity in the score line. 5. In the organization defined in claim 3, wherein: the distortion in the alignment of the score line comprises a portion extending out of the plane of the lid.
6. In the organization defined in claim 1, including:
a disruption of the lid surface at the score line forming a distortion in the alignment of the metal neck at the disruption point, whereby the aforesaid hinging action, responsive to flexing of the tab, effects a rupture of the neck at the point of disruption of the lid surface.
7. In the organization defined in claim 6, wherein:
said disruption is a crease traversing the score line and metal neck with a portion of the score line and metal neck out of the plane of the can lid.
8. In the organization defined in claim 7, wherein:
the lid is raised out of its normal plane by the crease to form a raised dimple at the crease and to cause the metal neck to be prestressed at the disruption.
9. In the organization defined in claim 6, wherein:
the disruption is a double crease; and
wherein the score line and metal is a W-shaped disruption at the double crease.
10. In the organization defined in claim 1, wherein:
an aperture is formed in the can lid by underfolding a rim about the said aperture;
said tab is underneath the underfolded rim; and
the score line is about the tab periphery at the underfolded rim.
11. In the organization defined in claim 9, wherein:
a crease-like disruption traverses the score line and dimples the underfolded rim.
12. In the organization defined in claim 10, wherein:
the dimple is raised out of the plane of the lid and at the pouring end thereof to form a spout-like member when the tab is pushed into the can and to cause the metal neck at the dimple to be prestressed.
13. In the organization defined in claim 10, wherein:
the aperture is elongated with a pouring end at one end of the lid and a venting end at the opposite end of the lid; and wherein said crease-like disruption is at the pouring end of the aperture and the score line terminates short of the venting end, whereby to form a hinging section integral with the can lid.
14. In a can lid having a push-in tab with the outline of the tab being defined by a line of weakened structure which will break responsive to flexing action, the improvement wherein:
at least a portion of said tab is a flexible dome convexing upwardly from the surface of the tab but is adapted to be pushed downwardly to concave below the surface of the lid whereby the flexing of the dome from the convex to the concave position produces a hinging action about the aforesaid line of weakened structure to facilitate severance thereof and separation of the tab from the lid.
15. The organization defined in claim 14, wherein the surface of the tab includes:
lineal irregularities in the general direction of the tab outline whereby to facilitate flexing the dome portion of the same from the convex to a concave position.