Patent Application
20120125935
Embodiments of the present invention generally relate to containers and container end closures, and more specifically metallic beverage container end closures adapted for interconnection to a neck of a beverage container body.
Containers, and more specifically metallic beverage containers, generally contain a neck or an upper portion that is adapted for interconnection to a metallic end closure. The container end closure is formed from a flat sheet of metallic material and generally includes a pull tab or other form of stay on tab (SOT). Beverage containers commonly store carbonated beverages, thus, both the container body and the container end closure are required to sustain internal pressures up to 90 psi without catastrophic failure or permanent deformation. Further, depending on the various conditions that the sealed container is exposed to heat, over fill, high CO2 content, vibration, etc., the internal pressure in a typical beverage container may at times exceed 90 psi. Thus, the container and end closure must be designed to resist deformation and failure while utilizing thin metallic materials.
Beverage containers are manufactured of thin and durable materials, such as aluminum, to decrease the overall cost of the manufacturing process and the weight of the finished product. It is also desirable to reduce the volume of material needed to fabricate the container end closure by optimizing the geometry and to more effectively improve buckle resistance and deformation. Accordingly, there exists a significant need for a durable beverage container end closure that can withstand high internal pressures associated with stored carbonated beverages and external forces applied during shipping, yet which is manufactured with durable, lightweight, reduced gage metallic materials with geometric configurations that reduce material requirements.
In an attempt to decrease material costs and improve strength, end closure engineers position the central panel proximate to the upper portion of the peripheral curl, which can result in other performance issues. More specifically, container end closures with a raised central panel height may experience problems associated with “tab-over-chime.” “Tab-over-chime” refers to a geometry where the pull tab is located above the height of the container, which creates stacking problems and thus potential damage during shipping and increased expenses. Thus, it is a challenge to design a container end closure that has improved geometry so that reduced gauge aluminum materials may be used while maintaining buckling and deformation performance of the end closure.
Previous attempts have been made to manufacture container end closures with unique geometric configuration in an attempt to provide material savings and improve strength. One example of a prior art beverage can end may be found in U.S. Pat. No. 7,100,789 to Nguyen et al., which is incorporated by reference in its entirety. Nguyen discloses a beverage container end closure that utilizes less material and has a chuck wall with improved buckle strength attributed to an inwardly oriented concave arch with a radius of curvature between about 0.015 inches and 0.080 inches. Container end closures that employ other unique geometries are disclosed in U.S. Pat. Nos. 7,506,779; 5,685,189; 6,460,723; 6,968,724 and U.S. Patent Application Publication Nos. 2002/015807 and 2005/0029269, which are each incorporated herein by reference.
The following disclosure describes an improved container end closure that is adapted for interconnection to a container body and that employs countersink and chuck wall geometry that decreases material costs while maintaining or improving performance.
It is thus one aspect of various embodiments of the present invention to provide a metallic container end closure with a novel geometry that can withstand significant internal pressures at times exceeding 90 psi, yet saves material costs. Although the end closures described herein generally apply to beverage containers for carbonated beverages, it should be appreciated by one skilled in the art that various aspects of the invention may be used for any type of container. In one embodiment of the present invention, these attributes are achieved by providing a countersink with an inner panel wall and an outer panel wall that are not parallel or slightly offset to a normal axis that passes through a horizontal plane of a substantially horizontal central panel. For example, one embodiment has an outer panel wall of the countersink that is interconnected to a lower portion of the chuck wall at an angle of about 21 degrees to define an outwardly disposed wall portion, and an inner panel wall, which is substantially parallel to the outer panel wall.
It is a further aspect of the present invention to provide a container end closure with an inner panel wall oriented outwardly away from the normal axis of the central panel. In one embodiment, the inner panel wall is disposed at an angle between about 20° and 30° from the normal axis of the center panel. In a preferred embodiment, the inner panel wall is disposed at angle between about 24° and 26° from the normal axis. In a more preferred embodiment, the inner panel wall is disposed at angle of approximately 25° from the normal axis.
In another aspect of the present invention, a method for forming a beverage can end closure is provided, wherein the container end closure is provided with a countersink radius of no greater than about 0.015 inches, and which is generally positioned at a depth no greater than about 0.084 inches from the central panel. Furthermore, the method forms a metallic end closure with a container having both inner and outer panel walls that are oriented outwardly from a vertical plane, and which utilizes a “reforming” process that alters the original geometry of the end closure or “shell.”
In another aspect of the present invention, a container end closure is provided that is manufactured with conventional manufacturing equipment. Thus, existing and well-known manufacturing equipment and processes can be implemented to produce an improved beverage can container end closure as contemplated herein. In another embodiment standard punches and dies used in container manufacturing industry are utilized. After the end closure is initially formed, a “reforming” process is performed to alter the geometry of the container end closure.
It is another related aspect of the present invention to provide a beverage container end closure that saves material costs by reducing the size of the blank material and/or utilizing thinner materials that have improved aluminum alloy properties. Thus, the integrity and strength of the beverage can end closure is not compromised, material costs are significantly reduced, and/or improved material properties are provided.
It is thus one embodiment of the present invention to provide a container end closure adapted for interconnection to a container body, comprising: a peripheral curl adapted for interconnection to a side wall of the container body; a chuck wall interconnected to said peripheral curl and extending downwardly at an angle of at least about 8 degrees as measured from a vertical plane; an outer panel wall interconnected to the lower portion of the chuck wall, said outer panel wall being angled about 8 degrees relative to the vertical plane in an outward direction away from a central longitudinal axis of the container; a countersink interconnected to a lower portion of said outer panel wall and having a radius of curvature less than about 0.017 inches; an inner panel wall interconnected to said countersink and extending upwardly at an angle of between about 15 degrees and 30 degrees as measured from the vertical plane; a central panel interconnected to an upper end of said inner panel wall and raised above a lowermost portion of said countersink at least about 0.084 inches.
It is yet another aspect of the present invention to provide a container end closure, comprising: a circular end wall adapted for interconnection to a side wall of a container; a chuck wall integrally interconnected to said circular end wall and extending downwardly, said chuck wall also interconnected to an outer panel wall; a countersink interconnected to a lower portion of said chuck wall and a lower portion of an inner panel wall and having a radius of curvature less than about 0.017 inches, said inner panel wall being outwardly angled about 25° relative to a vertical plane; and a central panel interconnected to an upper end of said inner panel wall and raised above a lowermost portion of said countersink no greater than about 0.084 inches.
It is still yet another aspect of the present invention to provide a method of manufacturing a metallic end closure, comprising: providing a preformed metallic end closure comprised of: a peripheral curl and a chuck wall extending downwardly therefrom at an angle of at least about 13 degrees as measured from a vertical plane, a countersink having an inner panel wall and an outer panel wall, and a central panel interconnected to an upper end of said inner panel wall; providing a reforming tool which generally comprises an upper cap and a lower cap that provides pressure to deform said metallic end closure, said countersink being held in place by at least one lower key ring; reforming said preformed metallic end closure by: engaging said central panel with said upper cap; engaging an underside of said central panel with a lower insert, said lower insert engaging with a lower retainer via a plurality of springs; contacting an outer surface of said upper cap with said chuck wall; contacting said countersink with said at least one lower key ring; moving said upper cap adjacent to said lower insert; and bringing an outer surface of said lower retainer in contact with said inner panel wall to deflect the inner panel wall, where said inner panel wall is deflected outwardly with respect to an axis perpendicular to said central panel.
The Summary of the Invention is neither intended nor should it be construed as being representative of the full extent and scope of the present invention. Moreover, references made herein to “the present invention” or aspects thereof should be understood to mean certain embodiments of the present invention and should not necessarily be construed as limiting all embodiments to a particular description. The present invention is set forth in various levels of detail in the Summary of the Invention as well as in the attached drawings and the Detailed Description of the Invention and no limitation as to the scope of the present invention is intended by either the inclusion or non-inclusion of elements, components, etc. in this Summary of the Invention. Additional aspects of the present invention will become more readily apparent from the Detailed Description, particularly when taken together with the drawings.
The accompanying drawings, which are incorporated herein, and constitute a part of the specification, illustrate embodiments of the invention and together with the general description of the invention given above and the detailed description of the drawings given below, serve to explain the principles of these inventions.
To assist in the understanding of one embodiment of the present invention the following list of components and associated numbering found in the drawings is provided herein:
It should be understood that the drawings are not necessarily to scale, and various dimensions may be altered. In certain instances, details that are not necessary for an understanding of the invention or that render other details difficult to perceive may have been omitted. It should be understood, of course, that the invention is not necessarily limited to the particular embodiments illustrated herein.
Referring now to
Referring now to
As shown in
The outward orientation of the countersink as provided herein has the advantage of increasing buckle strength of the container end closure. The table below provides buckle strength test data. Here, “Control Ends” describe prior art or conventional container end closures and are compared to “reformed” container end closures of embodiments of the present invention. On average, buckle strength is increased by about 0.8 psi.
Referring now to
During reforming operations, the end closure 2 is placed upon the lower insert 70 and the upper cap 46 is brought in contact with an upper surface 62 of the central panel 34. An outer surface 82 of the upper cap 46 contacts the chuck wall 10 and the outer panel wall 22 of the countersink 30 is contacted by at least one lower key 54, which is held in place by a clamp ring 58. The lower insert 70 rests upon the plurality of springs 78 that are associated with the lower retainer 74. The lower retainer 74 includes an angled surface 90, which will contact an inward facing portion of the inner panel wall 26.
During reforming, with particular reference to
The lower key ring 54 defines a pivot point that deflects the countersink outwardly. In one trial the pivot point was set about 0.0216 inches below the central panel 34 and a 0.0500 inch improvement to “tab to chime” distance was achieved. Again, as used herein “tab to chime” refers to the distance from the central panel to the top of the peripheral curl. This pivot point position also increased the buckle strength of the container end closure by about 0.8 psi.
While various embodiments of the present invention have been described in detail, it is apparent that modifications and alterations of those embodiments will occur to those skilled in the art. However, it is to be expressly understood that such modifications and alterations are within the scope and spirit of the present invention, as set forth in the following claims. Further, the invention(s) described herein is capable of other embodiments and of being practiced or of being carried out in various ways. In addition, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.
