Abstract:
The disclosed invention describes a container end that can be easily opened and does not rely on a conventional metal tab, riveted onto the end, thereby avoiding the problems and the cost associated with such a tab. The invention utilizes a traditional container end shell with a separate and distinct piece that is formed independently and is inserted into a countersink which is placed on the outer surface of the container end shell. The removal of this separate piece exerts a force or causes a change in the properties of the container wall in the countersink area, initiating and proliferating a discontinuity in the container wall, thereby creating an opening in the container. This change in the properties of the container wall can be mechanical, chemical, thermal or any other modality, which has the ability to influence the integrity of the container wall.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of U.S. provisional application No. 60/333,953, entitled “EASY-OPEN CONTAINER END,” filed Nov. 27, 2001, the entire disclosure of which is herein specifically incorporated by reference for all that it discloses and teaches. 
    
    
     BACKGROUND OF THE INVENTION 
     a. Field of the Invention 
     The present invention relates to a device and method of production for facilitating an easy-open end for a container. 
     b. Description of the Background 
     Full aperture easy-open can ends for food and non-food products have been present in the marketplace for more than 30 years. Nearly all feature a tab, which is formed independently and is riveted on to the container end shell. The material in the shell is scored near the outer diameter of the end so that when the tab is lifted, the tab perforates the score and then the score fractures as the tab is pulled back. Numerous advancements have been made on score design, tab design, protective folds to reduce the risk of cuts to the user, etc. Even so, the basic premise of the design, function and manufacture of conventional easy-open can ends, has remained nearly unchanged for the past quarter century. 
     Conventional easy-open can ends experience a variety of problems. In many instances, the forces necessary to fracture and propagate or tear the score can be excessive, especially for older consumers. Because this score is a point of structural debility, present designs are forced to attempt to minimize this weakness in order to stand up to processing and distribution. This conflict has resulted in preventing significant progress in reducing fracture and tear forces. These scores are also subject to corrosion in many applications when exposed to the product or environment. In addition to the problems created by the scoring of the can ends, numerous geometrical problems can arise when these containers are utilized in hyper or hypobarometric applications. For example, when cans are vacuum-sealed, the center panel of the container end is pulled inward which thereby forces the tab downwardly. This can make access to the tab difficult in many cases. Similarly, in pressure pack applications where a domed shaped end is required, conventional scoring and tab openings are not suitable. 
     Many conventional easy-open can ends also require the use of a riveting mechanism to retain the tab in place. These rivets can add considerable time and expense to the manufacturing process and can be sources of corrosion, fractures and leaks. Because basic easy-open end designs are not optimized for strength relative to buckle resistance, they require the use of heavy gauge materials that add to product weight and cost. On most designs used for processed food products, a countersink is required to meet minimal strength requirements. This countersink pushes the score and opening diameter towards the center of the can, often impeding the removal of the food product, especially with products that are semi-solid (like pet food). 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the disadvantages and limitations of the prior art by providing a container end that can be easily opened and does not rely on a conventional metal tab, riveted onto the end, thereby avoiding the problems and the cost associated with such a tab. The present invention can utilize a traditional can end shell, with a unique design that allows traditional double seaming of the end onto the can body. One embodiment of the present invention utilizes a traditional container end shell with a separate and distinct ring piece that is formed independently and is inserted into a closed loop countersink which is placed on the outer surface of the container end shell. The removal of this ring exerts a force in the countersink area, initiating and proliferating a discontinuity in the container end, thereby creating an opening in the container. Another embodiment functions the same as the first embodiment except the score in the countersink area is first pierced before the discontinuity is proliferated. 
     The present invention may therefore comprise a method of creating an opening in a closed shell container comprising: creating a closed loop countersink that protrudes inward from the outer surface of the container shell, creating an area of weakness throughout the closed loop on a portion of the countersink to facilitate preferential separation along the area of weakness, placing a semi-toroidal shaped ring within the countersink, the countersink having a depth greater than the radius of the ring, crimping the countersink on at least one lateral surface to a dimension less than the diameter of the ring, between the portion of the countersink that retains the ring and the outer surface of the container shell, to retain the ring within the countersink, removing the ring from within the crimped countersink to effect a change in the material properties throughout the area of weakness on the countersink thereby propagating a discontinuity in the container material and creating the opening in the closed shell container. 
     The present invention may also comprise a device for creating an opening in a closed shell container comprising: a closed loop countersink that protrudes inward from an outer surface of the container shell, an area of weakness throughout the closed loop on a portion of the countersink that facilitates a preferential separation along the area of weakness, a semi-toroidal shaped ring placed within the countersink, the countersink having a depth greater than the radius of the ring, a crimp to retain the ring within the countersink on at least one lateral surface of the countersink to a dimension less than the diameter of the ring, the crimp located between the portion of the countersink that retains the ring, and the outer surface of the container shell, a rivetless actuator to remove the ring from within the crimped countersink, the removal effecting a change in the material properties throughout the area of weakness on the countersink and create the opening in the closed shell container. 
     Numerous benefits may be afforded by the disclosed embodiments and include the elimination of conventional rivets or tabs and the problems associated with these parts. By forming the metal around the ring in the countersink area, there will be considerable enhancement of strength with respect to internal pressure and vacuum holding ability, leading to potential reduction or light weighting of metal used. With this invention, fracturing of the score will occur at one or two points at a time. This reduces tear forces on the end as opposed to the process used by conventional ends. This design is also less susceptible to score fractures that can occur during processing or distribution due to pressure on the tab. Also, the ring material can be specified to also act as a seal or protective material over the scored area, thereby preventing corrosion or unintentional opening. 
     The disclosed embodiments are highly versatile and can be used for instance with pressure packs where a dome can be incorporated inside the countersink area, adding considerably to strength since the dome area can have a of smaller diameter than a full dome on the same diameter end. Thus, the embodiments are more compatible with aftermarket devices to further enhance the ease of opening. The ability to use the removed container end to re-close the container offers a great advantage over conventional containers. This feature is further enhanced with the O-ring type seal produced by embodiments in which the ring is retained on the outer circumference of the removed end. Manufacturing cost benefits are realized since there is a reduction in the material gauge and the elimination of the rivet and tab. These costs are likely to be less than conventional easy-open can ends and could potentially rival the cost of non-easy open ends due to the enhance strength of the design. 
     Further advantages to the ease of use may be realized with the present invention. Since the inner panel of the can end will be removed without direct contact with fingers, the end should be less prone to cause cuts and abrasions. Furthermore, with the score in the countersink area, the residual material is less and potentially can be protected by the ring, also enhancing safety. By utilizing a large diameter inner panel, a larger aperture opening is possible leading to easier removal of product. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the Drawings, 
     FIG. 1 is a drawing showing a container end with a circular countersink that has been scored to facilitate a sheer or fracture site. 
     FIG. 2 is a drawing showing a container end of FIG. 1 with a ring attached on one end to the shell and inserted into the countersink. 
     FIG. 3A is a drawing showing a container end of FIG. 2 that has been crimped to facilitate retention of the ring and to produce an interference by which fracture forces are produced by the removal of the ring. 
     FIG. 3B is a drawing showing a container end of FIG. 3A that has been fractured by the forces produced by the removal of the ring. 
     FIG. 4 is a top view drawing of a typical embodiment such as in FIG. 3A showing the ring after being inserted and attached. The countersink area reformed with the metal above the radius of the top of the ring and partially closed on one or both sides of the countersink. 
     FIG. 5 is a top view drawing of a typical embodiment such as in FIG. 3A additionally showing the ring with a grip tab to initiate a fracture in the score. 
     FIG. 6 is a top view drawing of a typical embodiment of a rivetless actuator that is integrally part of the ring material that is crimped in the scored countersink of the container end. 
     FIG. 7 is a side view drawing of section  7 — 7  of FIG. 6 showing a typical embodiment of a pull tab that is integrally part of the ring material that is crimped in the scored countersink of the container end. 
     FIG. 8 is an expanded top view drawing of a typical embodiment such as in FIG.  6  and FIG.  7 . 
     FIG. 9 is an axial cross sectional view of section  9 — 9  of FIG. 8 showing detail of the ring within the scored countersink. 
     FIG. 10 is an axial cross sectional view of section  10 — 10  of FIG. 8 showing detail of the score piercing mechanism of the one-piece pull tab and ring within the scored countersink. 
     FIG. 11 is a radial cross sectional view of section  11 — 11  of FIG. 8 showing detail of the score piercing mechanism of the one-piece pull tab and ring. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While this invention is susceptible to embodiment in many different forms, there is shown in the drawings and will be described herein in detail specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not to be limited to the specific embodiments described. 
     In one embodiment, an opening is facilitated by utilizing a countersink that is typically placed as close as possible to the outer rim of the container to minimize the undercut area that might interfere with dispensing of the container contents. The end is scored in the countersink area in a conventional method utilizing any of a variety of techniques. A separate and distinct ring or tear-ring is inserted into the countersink area on the outside of the container end with one end of the ring being attached to the container mechanically and/or adhesively. The opposing end of the ring may contain a feature for gripping such as a pull tab or other type of rivetless actuator. Once the ring is inserted into the countersink, the countersink is reformed, or crimped, around the diameter of the material that makes up the ring. The score may be created on the countersink either before or after the ring is inserted and crimped in place within the countersink. The countersink is now in a position of interference with the removal of this ring. When upward pressure is exerted on the ring, it forces the countersink to expand in such a way that it causes a shear or fracture to initiate at the score. This fracture may be assisted by material fatigue experienced by crimping and expanding the countersink area. As the inserted ring is removed throughout the entire circumferential countersink, a tear occurs at the scored portion of the container end, thus, producing an opening. This removal can occur in a unidirectional manner, tearing all the way around the perimeter of the removed portion of the container end with a continuous strand of material. This removal can also occur bi-directionally, where the tear is propagated in both directions with a closed loop of material around the initial fracture point until the discontinuities reunite and establish separation between container and end. 
     FIG. 1 is a cross section of an implementation of the present invention showing a container end  100  with a circular, closed loop countersink  102  that has been scored  104  in a conventional manner to facilitate a sheer or fracture site. In such an application, a typical can end cap is manufactured with a conventional or slightly modified countersink  102 , scored  104  in such a manner to facilitate a sheer or fracture that circumferentially excises the inner portion of the end cap to produce an opening. This score  104  can be placed on either side or both sides of the material that makes up the countersink  102 . 
     FIG. 2 is a cross section of an implementation of the present invention showing a container end  200  with a countersink  202  which has been scored  204  in a conventional manner to facilitate a sheer or fracture site with a ring  206  attached on one end to the container end  200  and inserted into the countersink  202 . 
     FIG. 3A is a cross section of an implementation of the present invention showing a container end  300  with a countersink  302  which has been scored  304  in a conventional manner to facilitate a sheer or fracture site with a ring  306  attached on one end to the container end  300 . The ring  306  is inserted into the countersink  302  that has been crimped  308  in both lateral sides to facilitate retention of the ring  306  and to produce an interference by which fracture forces are produced by the removal of the ring  306 . These fracture forces are transmitted to the score  304  to produce a sheer. 
     FIG. 3B is a cross section of an implementation of the present invention showing a container end  300  with a countersink  302  that has been fractured  332  by the removal of a ring  306 . The ring  306  is extracted from the countersink  302  that has been crimped  308  in both lateral sides, the interference caused by this removal causes force to be transmitted to the score  304  to produce fracture  332 . 
     FIG. 4 is a top view of a typical implementation such as in FIG. 3A showing the ring attached to a grip loop  410  after being inserted and attached and the countersink  402  area reformed with the metal above the radius of the top of the ring  406  and partially closed on one or both sides of the countersink  402 . After the end is seamed onto the can, an opening will be affected by pulling upward on the extended portion of the ring  406 , which will exert force on the score  404  by pulling the ring  406  through the reduced opening of the countersink  402  above the ring  406 . Upon pulling the length of the ring  406  out through this opening, the full score  404  will be fractured  432  and the center panel  412  will be removed by continuing to lift on the ring  406 . Whereas this ring  406  can pull in either one or both directions to facilitate the tear on the score  404 , FIG. 4 demonstrates a ring  406  that is a continuous closed loop of rigid material. The ring  406  produces a fracture  432  in the score  404  in a bi-directional manner to create the opening. 
     FIG. 5 is a top view of a typical implementation such as in FIG. 3A additionally showing the ring with a pull tab  510  to initiate a fracture in the score  504 . Also shown is the ring  506 , which is inserted into (and possibly attached to) the countersink  502  and reformed with the metal above the radius of the top of the ring  506  which is partially closed on one or both lateral sides of the countersink  502 , i.e., crimped  508 . After the container end is seamed onto the can, an opening will be affected by pulling upward on the pull tab  510 , initiating a fracture or discontinuity in the score  504 . The pull tab  510  is also attached to the ring  506 , which will exert force on the score  504  and propagate a tear by pulling the ring  506  through the reduced opening of the countersink  502  above the ring  506 . Upon pulling the length of the ring  506  out through this opening, the entire score  504  fracture  532  will be propagated from a transfer of force created by deforming the crimp  508  with the ring  506  and the center panel  512  will be removed by continuing to lift on the ring  506 . Whereas this ring  506  can pull in either one or both directions to facilitate the tear on the score  504 , FIG. 5 demonstrates a ring  506  that is a continuous strand of rigid material. The ring  506  produces a fracture  532  in the score  504  in a uni-directional manner to create the opening. 
     An additional implementation can include a ring that is attached at a point to the portion of the container wall, which is intended to be removed. Thus, when the ring is fully excised from the countersink, and the container wall becomes nearly or fully discontinuous, additional pull on the ring is used to remove the surplus material. The aforementioned implementations may allow for an inner dome necessary for pressure packed food products, as well as the absence of such a dome as would be used with vacuum packed food products. 
     An additional implementation can include a countersink that is not a complete closed loop. In this instance, the center panel of the container end remains attached to a small portion of the container and hinges on that remaining material to facilitate an opening. 
     FIG. 6 is a top view drawing of a typical embodiment which includes a rivetless actuator, pull tab  610  or lever that is integrally part of, or attached to, the ring  606  material that is crimped in the circular, closed loop countersink  602  of the container end  600 . In this implementation, the original fracture is initiated by lifting the pull tab  610 , which connects to the ring  606 , at a point that is slightly proximal to its distal end. This maximizes the lever arm of the pull tab  610  by using the ring  606  as a fulcrum to transfer force from the short lever arm of the pull tab  610  to the opposing end of the ring  606  material which is in contact with the scored section (not shown) of the counter sink  602 , and initiates a discontinuity in the score. Once a discontinuity in the score is realized, the tear can be easily propagated and in one or both directions by further pulling of the pull tab  610  in a direction perpendicular to the center panel  612 . One implementation allows the ring  606  to remain attached to the center panel  612  of the container after it has been removed. This facilitates the ability to reclose the container by replacing the center panel  612  in its original position in the container end  600 , allowing the ring  606  to function as an O-ring type seal around the circumference of the newly formed container opening. 
     FIG. 7 is a side view drawing of section  7 — 7  of FIG. 6 showing a typical embodiment of a pull tab  710  that is integrally part of the ring  706  material that is crimped in the scored countersink of the container end  700 . FIG. 7 shows how the pull tab  710  can be placed in a recessed manner on the container end  700  and how the ring  706  is set into the countersink  702  that is formed into the container end  700 . With this configuration, there is no need to locate the pull tab  710  in any specific radial orientation within the countersink  702 , thus, simplifying manufacture. 
     FIG. 8 is an expanded top view drawing of a typical embodiment such as in FIG.  6  and FIG.  7 . As shown in FIG. 8, the pull tab  810  contains a standing rib  814  on its top surface to maintain stability and prevent buckling when the pull tab  810  is lifted. The ring  806  attached to the pull tab  810  is fit snugly into the scored countersink  802  where the ring  806  is crimped and held in place on one or both sides. This countersink  802  extends in a circular fashion around the entire outer edge of the container end  800 . 
     FIG. 9 is an axial cross sectional view of section  9 — 9  of FIG. 8, showing detail of the score piercing ring section  918  of the one-piece pull tab  910  and ring  906  within the countersink  902  containing a score  904 . As shown in FIG. 9, the axial cross-section of the score piercing ring section  918  is noncircular and contains a portion of high curvature  924  at a point opposite to the connection to the pull tab  910  and corresponding to a point nearest to the score  904  on the countersink  902 . This point of high curvature  924  serves to maximize the sheer force distributed from the pull tab  910  to the score  904  and initiate a fracture site. As further shown in FIG. 9, the pull tab  910  attaches to the score piercing ring section  918  at a point slightly proximal to the distal end of the pull tab  910 . This serves to create a lever action between the long and short end of the pull tab  910  with a point of connection between the ring and pull tab corresponding to the center point of the ring axis  920  thereby acting as a fulcrum. With the score piercing ring section  918  being held in a position as shown in FIG. 9 by the crimp  908  within the countersink  902 , the upward force of pulling the pull tab  910  transmits an effective sheer force which is maximized by the point of high curvature  924  directly to the score  904  causing a discontinuity in the container end  900 . 
     The center panel  912  of the container end  900  is then easily removed by propagating this fracture to the entire circumference. This is accomplished by an upward pulling motion with a finger inserted into the pull tab  910  and a corresponding downward pushing motion with the thumb near the midline of the center panel  912 . After the center panel  912  of the container end  900  has been removed, the center panel  912  can now act as a recloseable cap for the container. The ring  906  is held in position by the inside portion of the countersink  902 , and allows the ring  906  to function as an O-ring-like seal with the remaining outer portion of the countersink  902  of the container end  900 . 
     FIG. 10 is an axial cross sectional view of section  10 — 10  of FIG. 8 showing detail of the ring  1006  within the countersink  1002  containing a score  1004 . As shown in FIG. 10, the axial cross section of the ring  1006  is semi-toroidal throughout most of its circumference with a marked change occurring only at the point directly under the connection to the pull tab  1010 . Directly on either side of the score piercing section  918 , (detailed in FIG. 9) the ring  1006  becomes more toroidal in shape throughout the rest of the circumference. In the area outlined in this axial cross sectional view, the pull tab  1010  is attached to the ring  1006  section in approximately a right angle to the center point of the ring axis  1020  and contains a partial cut  1030  in the material joining the pull tab  1010  member to the ring  1006  member. This partial cut allows the remaining material to act as a hinge point  1026  about which the arc of the pull tab  1010  is rotated. This hinge  1026  feature only exists on either side of the score piercing section  918  of the ring  1006  where the ring  1006  member attaches to the pull tab  1010  member. 
     FIG. 11 is a radial cross sectional view of section  11 — 11  of FIG. 8 showing detail of the score piercing mechanism  1118  of the one-piece pull tab  1110  and ring  1106 . As shown in FIG. 11, the radial cross-section of the ring  1106  is tapered  1128  from the toroidal ring section (that exists everywhere but near the pull tab  1110  section of the ring  1106 ) to the score piercing feature  1118  (that is located directly under the midline of the pull tab  1110  and directly opposite the standing rib  1114 ). This tapering  1128  of the ring  1106  exposes the score piercing feature  1118  of the ring  1106  and allows for greater transmittal of force from the pull tab  1110  to the score piercing feature  1118 . 
     The foregoing description of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and other modifications and variations may be possible in light of the above teachings. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and various modifications as are suited to the particular use contemplated. It is intended that the appended claims be construed to include other alternative embodiments of the invention except insofar as limited by the prior art.