NZ280381A - Stay-on-tab can end with bead on tear panel enabling wide contact with tab to enhance propagation of score line rupture - Google Patents

Description

New Zealand No. 280381 International No. PCT/ TO BE ENTERED AFTER ACCEPTANCE AND PUBLICATION Priority dates: 01.11.1995 Complete Specification Filed: 01.11.1995 Classification:^) B65D17/28 Publication date: 26 January 1998 Journal No.: 1424 NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION Title of Invention: Stay-on-tab end with bead on tear panel enabling wide contact with tab to enhance propogation of score line rupture Name, address and nationality of applicant(s) as in international application form: REYNOLDS METALS COMPANY, a Delaware corporation of 6601 West Broad Street, Richmond, VA 23230-1701, United States of America 2G 0 3 8 1 PATENTS FORM NO. 5 Fee No. 4: $340.00 PATENTS ACT 19S3 COMPLETE SPECIFICATION James fc Wells Ref: 11769/3 STAY-ON-TAB CAN END WITH BEAD ON TEAR PANE^ENA^Lgft^-WIDE CONTACT WITH TAB TO ENHANCE PROPOGATIOI f r SCORE LINE RUPTURE We Reynolds Metals Company, a corporation of Delaware, 6601 West Broad Street, Richmond, VA 23230-1701, United States of America hereby declare the invention for which we pray that a patent may be granted to me/us, and the method by which it is to be performed to be particularly described in and by the following statement: 1 (Followed by 1 A) 2 8 u o 0 * ;1A ;STAY-ON-TAB CAN END WITH BEAD ON TEAR PANEL ENABLING WIDE CONTACT WITH TAB TO ENHANCE PROPAGATION OF SCORE LINE RUPTURE ;Technical Field ;The present invention relates generally to end members of beverage containers, and, more particularly, to an easy-open, stay-on-tab (SOT) can end in which an attached tab is lifted to 5 partially sever and displace a scored tear panel, thereby creating a pouring or drinking opening, with the tab and tear panel remaining attached to the end. ;Background Art ;Aluminum or steel cans, typically filled with beer, soft 10 drinks, tea, juice, water, concentrate, or the like, are provided with an easy-open, stay-on-tab can end wherein a non-closed score line is formed in the end and the tab is secured to the end at a location immediately outside a portion of the score line by a fastener such as a rivet. In this type of end, the tab is 15 hingedly connected to the rivet. In operation, a force is supplied by the tab and through the hinge association with the rivet to the scored tear panel portion of the can end to initially rupture the score line. The continued application of force pushes the tear panel down into the container. The non-20 closed portion of the score line retains the scored tear panel with the end and the tab remains attached by the rivet to remain with the end. ;To facilitate a better understanding of the invention "in the description which is to follow, the location of various parts of 2 5 the tab, tear panel, and score line on the end will be identified by reference to clock positions. As used in this specification, and assuming that the end is held in a vertical plane with the ;28 0 3 8 ;2 ;tear panel located beneath the stay-on-tab, the 12:00 position is located above the tab along a longitudinal axis extending through the rivet to bisect the tab. The 6:00 position is located along the same axis below the tear panel, with the 3:00 and 9:00 positions being located to the right and left of the end, respectively, along an axis extending perpendicular to the aforementioned longitudinal axis. ;Certain types of failure sometimes occur when attempting to open the end. One type of failure is called "nose failure", wherein the initial opening action of the tab fails to "pop" the score line. ;Another type of failure is called "non-turnunder", which means that the rupture of the score line fails to propagate fully around the tear panel and instead gets only to a point, usually at about the 3:00 position, where the tab starts slipping and bends the metal of the partially opened tear panel metal down so that the tab then slips off the tear panel and becomes useless. ;Another problem concerns the opening of the tear panel through an insufficient angle, which means that the tear panel fails to completely swing down through about 80° to 90° from its original position so as to avoid blocking the opening. When this problem occurs, the tear panel swings down incompletely, i.e., typically only 30° to 40° from the plane of the can end, and therefore partially restricts the free flow of liquid through the opening. ;The foregoing non-turnunder and insufficient angle problems generally occur as a result of an inability of the tab to -act on the tear panel in a manner which creates a sufficiently pure shear force to fracture the score line and then continue to apply sufficient shear to propagate the score line completely, around the tear panel. These problems become exacerbated as larger openings are formed within can ends for either aesthetic reasons or to ensure greater pourability and drinkability. As used in this specification, a "larger opening" is an opening area defined by the tear panel in the range of approximately 0.5-0.75 square ;28 0 3 8 1 ;inch, which has been found desirable in can ends having a diameter in the range of about 202-211, using can makers' conventional terminology. A "standard size opening" is one having an area less than about 0.5 square inch and is typically 5 within the range of 0.40-0.47 square inch. Within the context of the larger opening, it will be appreciated that the geometry and longer path lengths of the tear panel necessitate a greater need to ensure proper creation and transmission of shearing forces to the score line throughout the entire opening process, and it is ;10 this consideration to which the present invention is directed. ;It should also be appreciated that the present invention may be used for a wide range of sizes of can ends, including 200-300. ;It is accordingly an object of the present invention to control the shearing action induced by the tab against the tear ;15 panel along the score line to ensure complete rupturing of same except in the area of the hinge. ;Another object is to control the application of the shearing force acting on the tear panel as a function of the propagation of the rupture of the score line. ;20 A further object is to facilitate the use of larger size openings in beverage container ends without encountering the problems of non-turnunders and insufficient angles. ;Summary of the Invention ;The present invention provides a stay-on-tab container end ;2 5 or lid wherein the score line defining the severable tear panel portion tears correctly and completely, except at a hinge portion thereof, so that the tear panel is opened and remains on the end. The tab and tear panel are structured to cooperate in a unique manner whereby multiple and changing points of contact between ;3 0 these parts during tab opening movement serve to generate shearing forces acting to rupture the score line, instead of tension forces which would disadvantageously bend the tear panel and result in non-turnunder or insufficient angle. ;1 ;to ;Kj I ;"I""' 1 1 . : ;'i ;> w i i i u_.d ;28 0 3 8 1 ;In the preferred embodiment of the invention, a stay-on-tab can end is formed with an end wall and a rupturable score line in the end wall defining most of the periphery of a non-removable tear panel, while leaving an integral hinge between the panel and 5 the remainder of the end wall. The score line extends away from one end of the hinge, around a bight where it is distant from the hinge, and back to the other end of the hinge. A tab extending generally parallel and close to an underlying area of the end wall has a rear part which is manually engageable for upward 10 lifting and a forward nose part overlying a minor portion of the tear panel. Attaching means are provided on the end wall in a region thereof adjacent the score line and outside the tear panel. The attaching means is non-detachably secured to connecting means on the tab. The attaching and connecting means 15 permit pivotal, movement of the tab when the rear part of the tab is partially lifted up from the container and while the forward nose end of the tab correspondingly swings down, whereby the score line is subject to initial rupture. In accordance with the invention, a bead is formed to project upward from the tear panel 20 upper surface while extending beneath the forward nose part of the tab. Continued pivotal movement of the tab, about an axis of rotation generally parallel to the underlying area of the end wall and close to the attaching means, is effective to propagate the rupture of the score line from the 12: DO position and to 25 swing the panel down about its hinge to the open position, by creating a second point or place of contact between the bead and the forward nose part of the tab. This second contact is spaced from the longitudinal axis of the tab and is located on the side of that axis where the propagation of rupture away from the rivet 30 is to occur (i.e., the side of the longitudinal tab axis opposite the side where the tear panel is hinged to the rest of the wall of the end). ;Directional terms used in this application will assume that the can end is oriented on a can standing upright with the pour 3 5 opening toward the viewer. Thus, the tab is above the end wall, ;20 0 33 1 ;the longitudinal axis of the tab extends through the rivet, the length of the tab is along that axis, the width of the tab is perpendicular to that axis, the front of the tab is toward the viewer, and the rear of the tab is away from the viewer. The 5 "length", "width", "front", and "rear" of the tear panel and the bead refer to the same directions as those of the tab, so that the lengths of the tear panel and bead lie along a diameter of the end wall and their widths lie along a chord of the end wall. ;In the preferred embodiment, the opening defined by this 10 score line is a large opening, having an area greater than 0.5 square inch in a container end having a size within the nominal range of 202-211. ;Conventionally a purpose of the bead in the tear panel is to take up slack in the metal created by scoring. In addition, the 15 bead is preferably continuous in the portion of the tear panel underneath the tab, in order to give the tear panel added rigidity transverse to the longitudinal axis of the tab. Thus, the tendency of the tear panel to bend across that axis is minimized, which helps to facilitate the transmission of shear 20 force to the score line. Moreover, by providing the bead beneath the tab and by providing two spaced points or places of contact of the tab with the bead, there tends to be a more uniform distribution of the tab load against the tear panel. In the preferred embodiment, and these two points of contact are ;2 5 separate from the point of contact between the center of the nose of the tab with the tear panel. The height of the bead is .011 inch, measured from the top surface of the flat portion of" the tear panel. It is theorized that once the tab also contacts these side points on the bead, relative to the center of the ;3 0 nose, the rupture of the score line is able to better propagate as a result of the tab having the aforesaid at least two points of contact with the bead. Preferably, in top plan view, the bead is formed in curvilinear, eyeball shape and generally follows the outline of the score. Its lens-like protuberance 3 5 .extends beneath the forward nose part of the tab. The ;CO ! ;t; t' 0" In Figure 4E, since the tear has now advanced to the 9:00 position, points of contact 40 and 46 are now relieved as a result of downward displacement of tear panel 16. The remaining point of contact 42 at the intersection of nose 24 with protuberance 34 is advantageously located to ensure that proper shearing action is applied to score line 18 to enable it to completely rupture up to end 30a proximate hinge portion 28 as well as being completely depressed downwardly into the can interior towards a 90° or vertical position. It should be noted that in going from Figure 4D to Figure 4E the input force of the theoretical second class lever has shifted from 46 (or some combination of 42, 40 and 46) to 42 only, and that the fulcrum has shifted from 42 to hinge 28. Thus as propagation progresses the distance between the fulcrum and the load at the end of rupture propagation has increased, while the distance between the fulcrum and the input force has decreased. This is advantageous, since at 3:00 maximum shearing force at the score line is the prime consideration, and after 3:00 maximum downward movement of the tear panel at the score line becomes the prime consideration.

As the final tear occurs in Figure 4F (at which point the tear strip is fully depressed downward into the aforesaid 90° position) the final point of contact between the tab nose 24 with the tear panel 16 begins to slide back towards the hinge 28.

In a can end having a nominal 206 diameter (using can maker's conventional terminology), and generally speaking-within the range of 200-300 diameters, the area of the standard opening is in the range of 0.42-0.475 square inch. Although not strictly necessary, the invention as described above is suitable for use in can ends having the aforementioned conventionally sized standard opening areas. However, in the preferred embodiment, the invention has particular preferred use in large can ends having score lines 18 defining large openings 20. As used in this specification, a large opening is considered to have an area U J b 1 12 of about between 0.5-0.75 square inch, and preferably about 0.65-0.67 square inch. As disclosed herein, they may have their major axis perpendicular to the longitudinal axis of the tab and their minor axis perpendicular to that axis, with the major axis being 5 greater than the width of the tab. Within the environment of such large openings, the additional mechanical advantage provided by points of contact 40, 42 and 46, in particular 46, is what enables the tear line to propagate past the 3:00 position in Figure 4D so as to result in proper and full opening as depicted 10 in Figure 4F.

In a further aspect of the preferred embodiment, the protrusion 34 is preferably located radially outwardly from an area of coining 48 which is typically formed around the periphery of rivet 22 during the manufacturing process. It is theorized 15 that since the metal in the coined area is relatively brittle better shearing action results when the protuberance 34 and particularly points of contact 42 and 46 therewith are located outside of this coined area 48.

Although a protuberance 34 constitutes the presently 20 preferred embodiment, it will be understood by one of ordinary skill in the art that other bead shapes may be utilized, including bead shapes which may not necessarily be entirely closed or symmetrical about the longitudinal axis of the: tab, so long as such other bead shapes will result in the multiple points 25 of contact 40, 42 and 46 with the shearing and leverage forces generated thereby as discussed above. However, it is further theorized that a closed bead is preferred since it tends to maintain the tear panel 16 flat and does not allow it to cave or buckle in during opening. 3 0 Moreover, while the desired contact between the tab and the tear panel during opening, and particularly the stage depicted in Figure 4D, has been determined primarily by the outline of the bead as viewed from the top (e.g., Figs. 1, 2, and 4A-4F) and the height of the bead as viewed in side cross section (e.g., Fig. 35 3) , it will be appreciated, that the configuration of the tab nose 13 as viewed from the top and side can also be modified to achieve the desired contact pattern in the progression of the opening process. A conventional tab has been disclosed in this application, but the tab nose could be designed to have a non-circular shape or may have downward projections.

It will be readily seen by one of ordinary skill in the art that the present invention fulfills all of the objects set forth above. After reading the foregoing specification, one of ordinary skill will be able to effect various changes, substitutions of equivalents and various other aspects of the invention as broadly disclosed herein. It is therefore intended that the protection granted hereon be limited only by the definition contained in the appended claims and equivalents thereof. 1+

Claims (12)

WHAT WE CLAIM IS 280 38 1

1. A metal easy-open can end with non-detachable means for making an opening therethrough suitable for pouring and drinking, the can end having a circular end wall, a rupturable score line in the end wall defining most of the periphery of a non-removable tear panel, while leaving between the tear panel and the remainder of the end wall an integral hinge whose length is substantially less than the maximum dimension of the tear panel, the score line extending away from one end of the hinge, around a bight where it is distant from the hinge, and back to the other end of the hinge, and the tear panel having its length on a diameter of the circular end wall, a tab extending generally parallel and close to an underlying area of the end wall, a rear part of the tab being engageable for upward lifting, and a forward part of the tab terminating in a nose at its front end, and a rivet located on said diameter and adjacent the score line, which rivet non- detachably connects the end wall to the tab and permits pivotal movement of the tab about an axis of rotation close to the rivet and generally parallel to the end wall when the rear part of the tab is lifted up from the end wall, whereby, when the rear part of the tab is lifted, the forward part of the tab is adapted to press down on the tear panel, so as to cause relative vertical movement between the tear panel and the rivet, initial rupture of the score line close to the rivet, propagation of the rupture away from the hinge, around the bight and back to the hinge, and swinging of the tear panel down about the hinge to an open position, wherein the improvement comprises the tear pmnntyflnrt timer t1l<7 oprninp; for j N'Z. PATENT OFFICE pouring and drinking, which has (a) the general shape of an oval, (b) its width, as measured pftrppnHi^ipREegcmwifi substantially greater than its length, and (c) an area greater than 0.5 in2. r w 2. elliptical. 28 0 3 8 1

2. The can end of claim 1, wherein a major portion of the score line is

3. The can end of claim 1, wherein the tear panel includes an upwardly projecting, closed bead having a portion generally following the outline of the bight of the score line.

4. The can end of claim 3, wherein a major portion of the bead is oval.

5. The can end of claim 3, wherein the bead passes between the nose of the tab and the rivet.

6. The can end of claim 5, wherein the bead is generally shaped like a horizontal cross-section of an eyeball whose lens projects toward the rivet.

7. The can end of claim 3, wherein the forward part of the tab and the tear panel are configured so that, after the nose of the tab has pressed down on the tear panel at an initial place of contact and caused the rupture to propagate from the rivet to a first point approximately one quarter of the way round the periphery of the tear panel which is farther from the hinge, the.forward part of the tab is adapted to press down on the bead at an offset place of contact which is laterally spaced from the nose of the tab and from said initial place of contact and is closer to the end of the rupture than said initial place of contact will create an increased, leveraged shearing force on the score line at the end of the rupture.

8. The can end of claim 7, wherein the bead passes between said initial place of contact and the rivet, so as to allow the nose of the tab to tension the flat metal of the tear panel enclosed by the bead. x It 28 0 3 8 1

9. The can end of claim 7, wherein the forward part of the tab presses on t^tear panel simultaneously at said initial place of contact and said offset place of contact.

10. The can end of claim 7, wherein the shearing force is created by a second class lever, the lever having an input force at said offset place of contact, a load at the end of the rupture, and its fulcrum at the second offset place of contact on the tear panel which is closer to the hinge than said initial place of contact is.

11. The can end of claim 10, wherein, after the rupture has propagated from the rivet to a first point approximately one quarter of the way round the periphery of the tear panel which is farther from the hinge, continued lifting of the rear part of the tab causes further propagation of the rupture approximately half way round the periphery of the tear panel to a second point diametrically opposite said first point, thereby shifting the input force of the second class lever from said offset place of contact to said second offset place of contact on the tear panel and shifting the fulcrum of the lever from said second offset place of contact of the hinge.

12. A can end substantially as herein described with reference to the accompanying drawings. Cv cjaws /