GB2103174A

GB2103174A - Easy open can end

Info

Publication number: GB2103174A
Application number: GB08123861A
Authority: GB
Inventors: Daniel Steve Cvacho
Original assignee: Individual
Current assignee: Individual
Priority date: 1981-08-04
Filing date: 1981-08-04
Publication date: 1983-02-16

Abstract

A tab 42 is rivetted at 26 to a tear strip and is twisted over and over to wrap the tear strip around the tab, which is finally located in a recess 44 in the can end. Ribs 34, 36a and 36b define the movement of the tab and protect the users lips from sharp edges when drinking. Similarly a depression 38 in the tear strip forms a raised pad to protect the nose and upper lip of the user. In one construction, there is a layer of sealant between the tab and strip where they are rivetted together. A sanitary cover may overlie the tear strip and part of the can rim and is rolled up with the strip when the can is opened. <IMAGE>

Description

SPECIFICATION Easy open can end construction This invention relates to an easy open can end construction and method of making same and, more particularly, to such a construction and method of making wherein the pull tab remains locked onto the container.

Background of the invention Heretofore it has been known to provide easy open can ends with pull tabs which remain affixed to the can. At the present time, most easy open can ends are of the so-called "push in" type where a portion of the can end is pushed downwardly into the liquid contents of the can.

The patents issued to Cudzik, namely 3,967,750; 3,967,752 and 3,967,753 are illustrative of this type of can end construction. The principal objection to this type is a lack of cleanliness in that the portion of the can end that is pushed into the liquid contents may contain dust, dirt or other contaminants that are directly introduced into the beverage.

A second general type of problem illustrated in much of the prior art patents is the failure to maintain control of the final position of the tear strip and pull tab. In many of these patents, the tear strip is loosely pulled back and the pull tab and tear strip are simply draped over the sides of the can. Thus, the user who drinks from the can is exposed to the raw edges of the tear strip.

Still another existing problem is the jagged sawtooth edge found on existing score line patterns. This problem is not readily observable although one can feel that a problem exists. This problem exists because of the tendency for a tear to follow first one side of the bottom of a score line and then to switch to the other side. This zigzag rupture pattern produces sharp sawtooth like edges at the bottom of the score pattern which will quite easily cut the user's tongue or lips.

Finally, the prior art easy open can ends have been plagued almost from the start by leaking rivets caused by cracking in the region of the rivet because of the extremely severe stresses encountered in forming a rivet from a single thickness of metal.

Summary of the present invention In the practice of the present invention all of the previously noted problems are effectively overcome. In particular, the easy open can end of the present invention does not push in a portion of the can end so as to contaminate the liquid contents of the container in that manner.

Secondly, the present invention provides for an interlocking of a tear strip portion and a pull tab whereby the two remain tightly entwined at a predetermined position of the can end. The problem of unsanitary can ends is dealt with effectively by the use of a bio-degradable sanitary cover for the tear strip which is wound up and interlocked with the tear strip and the pull tab in the opening operation.

The present invention also contains a solution to the cut lip problem which results from a sawtooth edge left along the edge of the score line by rounding or chamfering one of the bottom edges of the score pattern to insure that tearing always occurs on the opposite bottom edge which is maintained sharp.

Finally, the present invention provides a solution to leakers by forming the connection of the pull tab from a double thickness of metal.

Thus, it becomes necessary for the cracks in the two thicknesses of metal to be in substantial alignment before leakage will occur.

One final advantage produced by the can end construction of the present invention is that the pull tab can be made of a more simple construction and narrower, for example, than the tabs in the previously mentioned Cudzik patents.

In addition, the tab can be made from the same aluminum alloy as the aluminum alloy of the can itself. This is not true with respect to the Cudzik patents, and this makes a good recycling feature for the cans and can ends of the present invention.

The inherent advantages and improvements of the present invention will become more readily apparent upon reference to the following detailed discussion of the invention and by reference to the drawings wherein: Fig. 1 is a fragmentary perspective view showing the easy open can end construction of the present invention; Fig. 2 is a fragmentary perspective view similar to Fig. 1 but showing the easy open can end partially open; Fig. 3 is a fragmentary perspective view similar to Fig. 1 but showing the easy open can end at a stage of opening subsequent to Fig. 2; Fig. 4 is a fragmentary perspective view similar to Fig. 1 but showing the easy open can end fully open; Fig. 5 is a top plan view showing a modified form of the present invention; Fig. 6 is a top plan view similar to Fig. 5 with the easy open can end fully open;; Fig. 7 is a fragmentary elevational view of the can end taken in vertical cross-section along line 7-7 of Fig. 5; Fig. 8a is a fragmentary elevational view of the pull tab and can end taken in vertical crosssection along line 8a-8a of Fig. 1; Fig. 8b is a fragmentary elevational view of the pull tab and can end taken in vertical crosssection along line 8b-8b of Fig. 5; Fig. 9 is a top plan view showing another modification of the present invention; Fig. 10 is a fragmentary elevational view, drawn to an enlarged scale, and taken in vertical cross-section of a score line used in the present invention; Fig. 1 1 is a top plan view of a pull tab for use in being riveted to the can end in accordance with the present invention;; Fig. 12 is a fragmentary elevational view, taken in vertical cross-section, illustrating a prior art method of riveting a pull tab to a can end; Fig.13 is an elevational view of the pull tab of Fig. 11 taken in vertical cross-section along line 1 3-13 and showing its relationship to a can end shown in phantom prior to riveting; Fig. 14 is a fragmentary elevational view, taken in vertical cross-section, showing riveting apparatus prior to formation of a rivet; Fig.15 is an elevational view, taken in vertical cross-section, similar to Fig. 14 but showing the formation of the rivet; and Figs.16~19 are fragmentary perspective views of a modified form of the present invention illustrating progressive stages of opening of an easy open can end having a sanitary cover over the drinking area.

Detailed description of the invention Referring now to Fig. 1 of the drawings, an easy open can end is indicated generally at 20 which has a substantially flat central panel 21.

The attachment of the can end 20 to a can body 22 is shown in each of Figs.1~4. The easy open can end is shown to have a pull tab, indicated generally at 24, with a conventional rivet 26 or other suitable attachment of the pull tab 24 to the flat central panel 21. A score line pattern is defined by score lines 28 which are generally parallel and as shown in Figs.1~4 preferably curved. The score line pattern is further defined by having the score lines joined at one end 30 and open at the opposite end 32 whereby upon lifting of this score line pattern from the plane of the central panel 21, the tab and score line pattern remain attached to the can end.

A first upstanding bead member is shown at 34 which follows the intermediate contour of the left side score line 28 while along the opposite or right side score line 28 a discontinuous bead line is formed from a pair of upstanding bead members at 38a, Figs.2~4, and 36b. The bead members 36a, 36b perform two principal functions. First of all, they cooperate with the opposed upstanding bead member 34 in providing lip protection along the exposed edge of the score pattern when the score pattern is fully removed from the central panel 21 as in the position shown in Fig. 4 and, secondly, the bead members 36a, 36b serve to orient the pull tab 24 at a location substantially perpendicular to the score line pattern in a manner which will become more evident hereinafter.

In addition to the use of opposed bead rrembers to provide lip protection, a smooth surface abutment means 38 is provided as an additional protection for the face of the user by forming a recessed area within the score line pattern itself. The smooth surface abutment means 38 is so positioned with respect to the width of the pull tab 24 and the location of the rivet or other attachment 26 of the pull tab to the central panel 21 that after lifting the pull tab by means of an upturned end 40 in the manner illustrated in Fig. 2, the pull tab may then be twisted in the direction of the score line pattern as is illustrated in Fig. 3 for a predetermined number of half turns until the pull tab and interlocked tear strip portion is received within a recessed area 44.In the embodiment shown in Figs. 1-4, the pull tab 24 after being lifted is then twisted for one and a half turns or three half revolutions to reach the position shown in Fig. 4. In order to have the pull tab 24 and the interlocked tear strip portion lie substantially flat within the recessed area 44, its width is made at least ten times as great as its thickness. In the position shown in Fig.

4, the smooth surface abutment means 38 is positioned on top of the torn out portion of the tear strip so as to guard the user's face from contact with the raw edge of the interlocking portion of the tear strip. Fig. 7 shows an elevational view of the beads 34 and 36b as well as abutment means 38. It will be recognised that the score lines 28 permit severence of the score pattern and inversion of the abutment means 38 to protect the upper lip and nose of the user.

Similarly, the upstanding beads 34 on one side of the removed portion of the tear strip and beads 36a, 36b on the other side provide protection from the raw edge of the score line 28.

One means for orienting the pull tab 24 with respect to the score line pattern is illustrated in Fig.

8a. In this figure, the pull tab 24 is shown to have a slightly depressed central panel 42 and curled edge flanges 46. The spacing between bead members 36a, 36b is such as to closely receive a curled edge flange 46 nearest the center of the flat central panel 21 and the length of bead member 36a is such as to be received beneath the depressed central panel 42 and to locate the opposed curled edge flanges 46 properly.

Figs. 5 and 6 in combination with Fig. 88 show another means for orienting the pull tab 24 with respect to the score pattern. In this figure, the pull tab is again removed by lifting and twisting for one and one half revolutions, or three half turns, so that the pull tab and attached tear strip are moved from Fig. 5 position into the Fig. 6 position. Prior to opening, the pull tab 24 is held in place substantially at right angles to the curved score pattern by means of being positioned between the spacing provided for by bead members 36a, 36b which closely abut the fully depressed central panel 42 in the manner illustrated in Fig. 8b with opposed hemmed edges 46a resting atop the bead members 36a, 36b.

A further modification of the invention is illustrated in Fig. 9. In this figure, a pull tab indicated at 24a is attached to the can body by means of rivet 26 or other suitable means of attachment to the flat central panel 21 of the can end 20. In this figure, upstanding bead members 34, 36a (not shown) and 36b follow the contour of score lines 28 which are closed at one end beneath pull tab 24a and open at the opposite end. In this embodiment, two smooth surface abutment means 38a and 38b are disposed in series within the score line pattern. After lifting to pop the score 38, the pull tab 24a is twisted in the direction of the score line pattern toward the open end thereof.One complete revolution of the pull tab exposes the smooth surface abutment means 38a and one and a half revolutions of the pull tab 24a exposes the second smooth surface abutment means 38b atop the wound up score line at the pull tab to guard the face of the user against contact with the edge of the score line pattern as in the previous embodiment. Thus, in this embodiment, the user has the option of partial opening or full opening of the score line pattern depending upon the desired usage.

Referring now to Fig. 10, an enlarged view of a single score line is illustrated. The score line is indicated generally 28 in this figure and is shown to be impressed within a substantially flat central panel 21. The score line 28 has a rounded edge 48 and a sharp edge 49 at the bottom of downwardly and inwardly sloping side walls 50. The rounded edge 48 is rounded sufficiently so that tearing occurs along the opposite edge 49. A radius of from .001 inches through .003 inches for the rounded edge 48 has been found to be satisfactory while maintaining a sharp edge 49 by having a much smaller radius such as a radius of about .0002 inches on the scoring tool. Alternatively, the edge 48 may be chamferred. A chamfer of from .004 through .003 inches on a 45 degree chamfer has been found to be satisfactory while maintaining the same sharp edge at 49 as described previously.By making the score line 28 in this manner, the rupture occurs along edge 49 and does not zigzag from one side to the other. Therefore, the jagged edge heretofore encountered is eliminated.

Referring now to Figs. 1 5, there will be described a method of forming a rivet for the easy-open metallic can end in which a rivet is formed from two metal thicknesses rather than from a single metal thickness as in the prior art. In the formation of prior art rivets, it has been known to form the metal from the central panel progressively from a relatively large diameter area and gradually confining the formed metal to a small diameter nipple. Thus, it has been known to form an initial large diameter downwardly extending bubble in the flat central panel 21, then reversing the bubble by forming the bubble into an upstanding nipple of reduced diameter followed by a further shaping of the nipple. The embossing and debossing of the can end is then accomplished to form upstanding bead members such as 34, 36a, 36b as well as a depression for the recessed area 44.A score pattern for the opening strip is then placed on the central panel and the tab is then assembled to the end. In this latter assembly operation such as is illustrated in Fig. 12, the tab 51 is illustrated to have a cone shaped area surrounding an aperture 63. A top riveting tool is shown at 58 bordered by tab holding members 60 which may be spring loaded to engage a cone-shaped portion 56 of the ring pull tab 51. It should be observed that while Figs.

11-15 illustrate a ring pull tab, that the technique is applicable to pull tabs generally. The prior art is shown to use a bottom riveting tool 62 which extends through the hole in pull tab 51. A single thickness of metal is thereby formed at 66 which locks the ring pull tab 51 or other pull tab to the flat central panel 21. A major rejection of finished easy-open can ends occurs because the rivet ruptures in a plane substantially coincident with and in a radial direction from the top of the bottom riveting tool 62.

In the improved double thickness rivet, the same technique that is used to form a nipple 66 in the prior art can end is also employed to make a corresponding nipple 54 in the pull tab as illustrated in Fig. 13. A sealant or gasketing material 64 may be employed to be positioned between the underside of nipple 54 and the conventionally formed nipple 66 to seal against possible leakers. Fig. 14 shows the formed tab 51 in position over the flat central panel 21 located with the aid of annular depression 68 which surrounds the nipple 66. A top riveting tool 58 having tab holding members 60 spring loaded at 69 is again urged toward the pull tab 51 thus located on the can end central panel 21 and having a nipple 66 supported on a bottom riveting tool 62 so as to form the rivet of double thickness, that is, metal thicknesses 54 and 66 in Fig.15.

Thus, any comparable cracking of the rivet of the outer peripheral portion will require that both thicknesses of metal 54, 66 be cracked in substantially the same location in order for liquid within the container to leak therefrom.

Referring now to Figs.16~19, there will be described a further embodiment of the invention wherein a sanitary cover 70 is used to insure a sanitary drinking area on the container from which the consumer may drink. To this end, the sanitary cover 70 made by coated paper or plastic material, preferably bio-degradable, is suitably adhered to the end of the tab to cover the drinking area. The sanitary cover 70 has a chime covering portion 72 for the chime 74 of the container.

Fig. 1 7 illustrates the first step in the opening operation in which a pull tab 24 is lifted and then twisted as illustrated in Fig.18 until it reaches its final position shown in Fig.19 in which the sanitary cover is rolled up and interlocked between the pull tab and the tear strip. In this embodiment, a smooth surface abutment means 38a is exposed to protect the face of the user. The pull tab and tear strip with interlocked sanitary cover 70 dwell within a recessed area 44 on the container after a given number of half revolutions of the pull tab 24, such as three half revolutions.

A number of modifications may be made in the invention without departing from the spirit or scope thereof. For example, in place of utilizing hemmed or rolled edges for the pull tab, the latter may be oriented with one or more protrusions or beads on the can end which engage the side edges of the pull tab. Another possible arrangement is to use depressions in the can end into which a rolled edge 46 on one or both sides as illustrated in Fig. 8a would be lodged. Also the sanitary cover 72 may be made of different sizes and may cover more area than that shown in Figs.

1 6-1 9, if desired.

While presently preferred embodiments of the invention have been illustrated and described, it will be recognized that the invention may be otherwise variously embodied and practiced within the scope of the claims which follow.

Claims

1. An easy open can end construction for metallic beverage cans which comprises: a. a can end having a substantially flat central panel, b. a pair of generally parallel socre lines defining a tear strip in said flat central panel with said score lines being closed at one end and open at the opposite end, c. a pull tab secured to said flat central panel within said pair of score lines adjacent the closed end thereof, (1) said pull tab having a substantially flat body portion whose width is at least ten times its height, (2) said pull tab having its longitudinal axis positioned at substantially right angles to the longitudinal axis of said parallel score lines, (3) first orienting means on pull tab for maintaining the position of said pull tab with respect to said parallel score lines prior to opening the can end, (4) second orienting means on said can end cooperating with said first orienting means on said pull tab for maintaining the position of said pull tab with respect to said parallel score lines, d. said can end adapted to be opened by pivotal movement of said pull tab in a direction substantially at right angles to said score lines and then twisting for a given number of half turns in the direction of the score lines whereby said pull tab becomes interlocked with said tear strip and lies closely adjacent the central panel so as not to interfere with the nose of the user should the user drink directly from the can.

2. An easy open can end construction as defined in claim 1 including smooth surface means extending upwardly out of the plane of said substantially flat central panel serving as a guard means to prevent the face of the user from contacting the raw edge along the score lines after opening the can end.

3. An easy open can end construction as defined in claim 2 wherein said smooth surface means comprise upstanding bead members extending generally parallel to and exteriorly of said score lines.

4. An easy open can end construction as defined in claim 3 wherein one of said bead members is interrupted to define the orienting means for maintaining the position of said pull tab with respect to said parallel score lines prior to opening the can end.

5. An easy open can end construction as defined in claim 4 wherein said first orienting means on said pull tab constists of a rolled over edge which is positioned to dwell within the interruption of one of said beam members to maintain the position of said pull tab with respect to said parallel score lines prior to opening the can end.

6. An easy open can end construction as defined in claim 1 wherein said flat central panel includes smooth surface abutment means positioned within said tear strip which project downwardly therefrom but which upon twisting of said pull tab for a given number of half turns during the opening operation become repositioned to project upwardly from the tear strip to guard the face of the user from the raw metallic edge of the tear strip.

7. An easy open can end construction as defined in claim 6 which includes a plurality of smooth surface abutment means sequentially positioned within said tear strip and which become selectively repositioned to project upwardly from the tear strip upon twisting a different number of half turns of said pull tab to guard the face of the user from the raw metallic edge of the tear strip.

8. An easy open can end construction as defined in claim 6 wherein said substantially flat panel member is provided with a depressed well area into which extends said interlocked pull tab and tear strip extend upon twisting said pull tab a given number of half turns.

9. An easy open can end construction as defined in claim 6 wherein said generally parallel score lines intermediate their ends follow a generally arcuate path and said pull tab extends transversely away from said score lines in a direction toward the centres of curvature of said score lines.

10. An easy open can end construction as defined in claim 6 including smooth surface means extending upwardly out of the plane of said substantially flat central panel serving as a guard means to prevent the face of the user from contacting the raw edge along the score lines after opening the can end.

11. An easy open can end construction as defined in claim 10 wherein said smooth surface means comprise upstanding bead members extending generally parallel to and exteriorly of said score lines.

12. An easy open can end construction as defined in claim 11 wherein one of said bead members is interrupted to define the orienting means for maintaining the position of said pull tab with respect to said parallel score lines prior to opening the can end.

13. An easy open can end construction as defined in claim 12 wherein said first orienting means on said pull tab consists of a rolled over edge which is positioned to dwell within the interruption of one of said bead members to maintain the position of said pull tab with respect to said parallel score lines prior to opening the can end.

14. An easy open can end construction as defined in claim 1 including a sanitary cover member overlying at least a portion of said flat central panel with said cover member being rolled up with said tab member and said tear strip and becoming interlocked therewith.

15. An easy open can end construction for metallic beverage cans which comprises: a. a can end having a substantially flat central panel, b. a pair of generally parallel score lines defining a tear strip in said flat central panel with said score lines being closed at one end and open at the opposite end, c. a pull tab secured to said flat central panel within said pair of score lines adjacent the closed end thereof, (1) said pull tab having a substantially flat body portion whose width is at least ten times its height, (2) said pull tab having its longitudinal axis positioned at substantially right angles to the longitudinal axis of said parallel score liines, d. said can end adapted to be opened by pivotal movement of said pull tab in a direction substantially at right angles to said score lines and then twisting for a given number of half turns in the direction of the score lines whereby said pull tab becomes interlocked with said tear strip and lies closely adjacent the central panel so as not to interfere with the nose of the user should the user drink directly from the can.

16. An easy open can end construction as defined in claim 15 including smooth surface means extending upwardly out of the plane of said substantially flat central panel serving as a guard means to prevent the face of the user from contacting the raw edge along the score lines after opening the can end.

17. An easy open can end construction as defined in claim 15 wherein said flat central panel includes smooth surface abutment means positioned within said tear strip which project downwardly therefrom but which upon twisting of said pull tab for a given number of half turns during the opening operation become repositioned to project upwardly from the tear strip to guard the face of the user from the raw metallic edge of the tear strip.

18. An easy open can end construction as defined in claim 15 wherein said substantially flat panel member is provided with a depressed well area into which extends said interlocked pull tab and tear strip extend upon twisting said pull tab a given number of half turns.

19. An easy open can end construction as defined in claim 15 wherein said generally parallel score lines intermediate their ends follow a generally arcuate path and said pull tab extends transversely away from said score lines in a direction toward the centers of curvature of said score lines.

20. An easy open can end construction as defined in claim 15 including a sanitary cover member overlying at least a portion of said flat central panel with said cover member being rolled up with said tab member and said tear strip and becoming interlocked therewith.

21. In an easy opening can end of the type having a tear strip openable by a pull tab which upon opening remains attached to both the tear strip and to a container to which the can end is sealed, the improvement which comprises: a. a sanitary cover member which prior to opening the can end covers substantially all of the tear strip and whic is rolled up with the tear strip during the opening operation and which thereafter remains interlocked with the tear strip and the pull tab.

22. An easy open can end as defined in claim 21 wherein said sanitary cover is made from a coated paper material.

23. An easy open cam end as defined in claim 21 wherein said sanitary cover is made from a plastic material.

24. A method of making a score line for an easy open can end construction adapted to be sealed to a metallic beverage can, said score line being of the type opened by a pull tab and having downwardly and inwardly sloping sidewalls from the topside of the can end to the bottom of a trough which is bordered by a pair of edges spaced apart from each other from about .003 inches to about .006 inches, said trough being from about .004 inches to about .007 inches from the bottomside of said can end, said method including the steps of a. forming a sharp corner on one of said edges by providing a radius at said sharp corner of not more than about .0002 inches, and b. rounding the opposite corner by providing a radius of from about .001 inches to about .003 inches whereby tearing occurs continuously along said sharp corner of said tear line when said can end is opened by means of said pull tab.

25. A score line for an easy can end construction made by the process of claim 24.

26. A method of making a score line for an easy open can end construction adapted to be sealed to a metallic beverage can, said score line being of the type opened by a pull tab and having downwardly and inwardly sloping sidewalls from the topside of the can end to the bottom of a trough which is bordered by a pair of edges spaced apart from each other from about .003 inches to about .006 inches, said trough being from about .004 inches to about .007 inches from the bottom side of said can end, said method including the steps of a. forming a sharp corner on one of said edges by providing a radius at said sharp corner of not more than about .0002 inches, and b. chamfering the opposite corner from about .0004 inches to about .003 inches at about a 46 degree angle to the vertical.

27. A score line for an easy open can end construction made by the process of claim 26.

28. A method of forming a rivet for an easy open metallic can end which comprises the steps of a. forming an upstanding nipple on the main panel of a can end, b. forming a corresponding upstanding nipple on a metallic pull tab for said can end, c. supporting said pull tab on said can end by nesting the can end nipple within the pull tab nipple, d. providing a supporting riveting tool with a flat head and inserting said riveting tool within the nipple on said can end, e. and forming a rivet from two metal thicknesses by engaging the nipple on said pull tab with a complementary riveting tool while holding said pull tab and said can end in place under spring pressure.

29. A method of forming rivet as defined in claim 28 including the additional step of providing a coating between the two nested nipples to provide a gasket material therebetween.