Receptacles – Closures – With closure opening arrangements for means
Reexamination Certificate
2000-11-06
2002-06-18
Newhouse, Nathan J. (Department: 3727)
Receptacles
Closures
With closure opening arrangements for means
C220S906000
Reexamination Certificate
active
06405889
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates generally to closures of the type used for metal beverage containers and, more particularly, to stay-on-tab closures in which an attached tab is lifted to partially sever and displace a tear panel to create an opening for dispensing the contents of the container. The current invention relates to a stay-on-tab closure having a tear panel with low-relief contour features on the upper surface.
BACKGROUND OF THE INVENTION
It is well known to use closures, also referred to as “ends” or “lids,” for sealing metal beverage containers of the type used for packaging beer, carbonated soft drinks, juice, tea, water, and other liquids or fluids. These closures are typically formed of an aluminum alloy or steel, although other materials such as metal-plastic laminates or composites can also be used. A common type of closure, often referred to as a “stay-on-tab” closure, incorporates an attached tab which is lifted to partially sever and displace a tear panel defined by a frangible curvilinear score line. The downward displacement of the tear panel creates an opening for dispensing the contents of the container without the use of a separate opening tool. Both the tear panel and the tab remain attached to the closure after opening.
Conventional stay-on-tab closures typically include a center panel having a generally planar or slightly upwardly domed surface. A tear panel is defined by a curvilinear, but non-closed, frangible score line formed on the center panel which defines the general periphery of the tear panel but leaves a narrow integral hinge connecting the tear panel to the remainder of the center panel. An opening tab is secured to the center panel of the closure by a rivet or other such fastener hingedly connected to the tab. When one tab end is lifted upward, the tab applies forces to the tear panel and center panel to rupture the score line and displace the tear panel down into the associated container to form an opening through which the container contents can be dispensed. The non-closed portion of the score line forms a hinge which retains the tear panel with the closure. Similarly, the tab remains attached to the closure by its hinged connection to the rivet.
To facilitate the easy bending of the tear panel into the container during opening, conventional stay-on-tab closures connect the tear panel to the center panel using a narrow hinge, i.e., a hinge having a width less than about 25% of the maximum width of the tear panel. Unconventional container closures having displaceable panels and permanently affixed tabs are also known, such as described in U.S. Pat. No. 5,405,039 to Komura, and such closures may be referred to by some as “stay-on-tab” closures. The displaceable panels in such unconventional closures, however, are connected to the center panel by a hinge having a width significantly greater than 25% of the maximum width of the displaceable panel. For example, one closure in the previously mentioned Komura '039 patent provides a displaceable panel comprising approximately one-half of the top of the lid and a hinge having a width of approximately 100% of the maximum width of the displaceable panel. Because the forces relating to the opening and bending of such unconventional closures are significantly different than for conventional stay-on-tab closures, all further references to “stay-on-tab” closures in this application refer to closures having a hinge width less than about 25% of the maximum width of the tear panel.
All stay-on-tab container closures heretofore known include high-relief “contour features” formed in the tear panel and projecting substantially above the nearby generally planar surface of the tear panel. For the purposes of this application, a contour feature is considered to have “high relief” when the “total height”, or H
T
, of the feature is not less than about 2 times the thickness of the sheet material used to form the lid. The total height, H
T
, of a contour feature is the vertical distance from the highest point on the upper surface of the contour feature to the level of the underside of the surrounding generally planar tear panel material. One contour feature commonly used on tear panels is a raised curvilinear ridge generally referred to as a “bead.” It is known to use high-relief beads having a variety of configurations, when viewed from above, including a non-closed curve resembling the letter ACE (sometimes called a “C-bead”), a closed curve having one straight side resembling the letter “D” (sometimes called a “D-bead”), a closed curve of circular or oval shape, or an irregular closed or non-closed shape. For example, closures are known which are formed from sheet material having a thickness of about 0.0093 inches and having a high-relief bead on the tear panel with a total height, H
T
, in the range of about 0.0200 to 0.0230 inches, as are closures formed from sheet material having a thickness of about 0.0090 inches and having a high-relief bead on the tear panel with a total height, H
T
, of about 0.0180 inches. It must be noted that although beads are among the most common high-relief contour features found on tear panels, other high-relief contour features are also known, including ridges, panels, embossments, and various combinations of these features.
It was heretofore believed necessary to incorporate high-relief contour features on the tear panel of stay-on-tab container closures for one or more of the following reasons: 1) to serve as lateral stiffening or reinforcing structures on the tear panel so that the panel will not bow excessively or buckle during the opening operation, which can cause “nose failure” and “tuck-under” type failures; 2) to selectively distribute the forces of the opening tab across the tear panel to propagate the fracturing of the score line completely around the tear panel so the panel will not experience an “partial opening” type failure; and 3) to gather in the “slack metal” on the tear panel which results from the widening of the panel during formation of the score lines, thereby maintaining tension in the tear panel, the lack of which can also cause nose failure, tuck-under type failure, or partial opening type failure. A “nose failure” occurs when excessive bowing or buckling of the tear panel due to insufficient stiffness or insufficient tension allows the tab end to slip along the surface of the tear panel without rupturing the score line at all. A “tuck-under” type failure, also known as a “non-turn-under” type failure, occurs when the same factors cause the tab to only partially rupture the score line and not displace the tear panel far enough into the container to provide a useable opening. A “partial opening” type failure, also known as an insufficient angles type failure occurs when the score line fully ruptures, but bowing of the tear panel or inadequate distribution of tab forces prevents the tab from displacing the tear panel through a sufficient angle into the container to avoid obstructing the opening.
The operational problems described above are known for stay-on-tab container closures having “standard-size” openings, that is, openings defined by tear panels having an area of approximately 0.40 square inches, and the use of a high-relief bead or some other type of high-relief contour feature on the tear panel was heretofore believed necessary to overcome such problems. It was heretofore further believed that such operational problems are exacerbated on container closures incorporating so-called “large-size” openings, that is, openings defined by tear panels having an area of approximately 0.59 square inches or larger, and thus that the use of a high-relief bead or other contour feature on the tear panel was of increased necessity. See, for example, European Patent Application No. EP 0 704 382 A2.
Another factor affecting the performance of container closures is the-gauge, or thickness, of the material used to form the closures. At one time, stay-on-tab container closures were manufactured using sheet metal “stock” having a thi
Hylton Robin A
Metal Container Corporation
Newhouse Nathan J.
Storm & Hemingway LLP
Storm, Esq. Paul V.
LandOfFree
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