Patent Publication Number: US-7909196-B2

Title: Can end with tab for improved accessibility

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention relates to the manufacture of an opening tab for container ends; specifically opening tabs for retained-tab beer and beverage container ends. 
     BACKGROUND OF THE INVENTION 
     Pull tabs for container ends are used on various types of containers, including beer and beverage containers, food containers, and many other types of containers for household or industrial use. The most prevalent type of pull-tab container ends is the retained-tab end, which have a tab designed to remain on the container end after the container is opened, such as with beer and beverage metal containers. The typical beverage cans used today have a non-detachable tab, called the “ecology tab” because of the fact that the predecessor types of tabs were removed when the container was opened and were causing pollution concerns. 
     The typical non-detachable tabs used in the beverage container industry are of generally the same design. These tabs have a nose portion, a lift end portion, separated by a central body portion that has an aperture provided for securing the tab to the end by a rivet. The tab is manufactured separately from the end, and is secured to the end such that the nose is positioned over the scoreline of the end. When the tab is lifted at the lift end by the user, the nose of the tab is pushed down on the end panel to fracture the score and open the container. The rivet, therefore, acts as a fulcrum for the rotation of the tab, and a central hinge area of the tab bends adjacent the rivet across a hinge line of the tab. 
     A problem with the non-detachable tabs is the inability for the user to access the lift end due to the limited distance between the lift end and the central panel of the can end. This inaccessibility is compounded by the reduction of the area of the central panel as the can end diameter is reduced to lower metal cost. The spacing between the lift end and the central panel must be sufficient to allow the user to frictionally engage the tab while providing an upward force to initiate movement of the tab nose downward to fracture the score and open the container. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a can end for a container. The can end has a curl defining an outer perimeter of the can end. A chuckwall extends downwardly from the curl. The chuckwall is joined to a center panel. The center panel is centered about a longitudinal axis, and has a product side, a public side, a rivet, and a displaceable tear panel at least substantially defined by a frangible score and a non-frangible hinge segment. A non-detachable tab is staked to the center panel by the rivet. The non-detachable tab has a nose end extending over a portion of the tear panel, a lift end opposite the nose end, and a central webbing between the nose end and the lift end. The central webbing has a hinge region and a rivet island surrounding the rivet. The rivet island is at least partially surrounded by a first void region to provide a first exposed area of the center panel. The central webbing also has a second void region between the lift end and the first void region to provide a second exposed area of the center panel. The first and second void regions are separated by a narrow strip of the central webbing. A portion of the narrow strip extends downwardly and approaches the public side of the center panel wherein a height of the lift end of the tab above the public side of the center panel is maintained at a predetermined height. 
     It is also an object of the present invention to provide a non-detachable tab having a nose end extending over a portion of the tear panel, a lift end opposite the nose end, and a central webbing between the nose and lift end. The webbing has a hinge region and a rivet island surrounding the rivet. The rivet island is at least partially surrounded by a first void region to provide a first exposed area of the center panel. The central webbing also has a second void region between the lift end and the first void region to provide a second exposed area of the center panel. The second void region has a perimeter defined by a curl of the central webbing. A portion of the curl extends downwardly and approaches the public side of the center panel wherein a height of the lift end of the tab above the public side of the center panel is maintained at a predetermined height. 
     Other advantages and aspects of the invention will become apparent upon making reference to the specification, claims, and drawings to follow. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a top view of the public side of the can end of the present invention; 
         FIG. 2  is a cross-sectional view of the can end of  FIG. 1 ; 
         FIG. 3  is a top view of the public side of the can end of the present invention; 
         FIG. 4  is a cross-sectional view of the can end of  FIG. 3 ; 
         FIG. 5  is a top view of a non-detachable tab; 
         FIG. 6  is a cross-sectional view of a can end of the present invention having the tab of  FIG. 5 ; 
         FIG. 7  is a top view of a non-detachable tab; 
         FIG. 8  is a cross-sectional view of a can end of the present invention; 
         FIG. 9  is a cross-sectional view of a can end of the present invention; 
         FIG. 10  is a cross-sectional view of a can end of the present invention; 
         FIG. 11  is a top view of a tab of  FIG. 9 ; 
         FIG. 12  is a top view of a tab of  FIG. 10 ; 
         FIG. 13  is a top view of a non-detachable tab; 
         FIG. 14  is a cross-sectional view of the tab of  FIG. 13 ; 
         FIG. 15  is a top view of a non-detachable tab; 
         FIG. 16  is a cross-sectional view of the tab of  FIG. 15 ; 
         FIG. 17  is a cross-sectional view of a pressurized container including an end member with a non-detachable tab; and 
         FIG. 18  is a cross-sectional view of a prior art pressurized container including an end member with a non-detachable tab. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail a preferred embodiment of the invention with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the broad aspect of the invention to embodiment illustrated. 
     The present invention relates to a retained-tab can end for a container having improved accessibility and thus improved ease of openability. The retained-tab can end according to the present invention is typically a beer and beverage container end, having a retained tab and, therefore, being identified as “ecology” or “easy-stay” container ends. However, it is contemplated that the present invention may be use with other types of container ends, such as food and other containers in which a lift-tab is useful to open the container. 
     The Can End 
     Referring to  FIGS. 1 and 2 , the can end, or end closure, or end member,  10  for a container (not shown) has a central or center panel wall  12  having a seaming curl  14  for joining the wall to the container. The container is typically a drawn and ironed metal can, usually constructed from a thin plate of aluminum or steel, such as the common beer and beverage containers. End closures for such containers are also typically constructed from a cut edge of thin plate of aluminum or steel, formed into blank end, and manufactured into a finished end by a process often referred to as end conversion. In the embodiment shown in the Figures, the central panel  12  is joined to a container by a seaming curl  14  which is joined to a mating curl of the container. The seaming curl  14  of the end closure  10  is interconnected to the central panel  12  by a chuckwall  15  and a countersink area  16  which is joined to the central panel  12  outer peripheral edge of the central panel  12 . This type of means for joining the central panel  12  to a container is presently the typical means for joining used in the industry, and the structure described above is formed in the process of forming the blank end from a cut edge of metal plate, prior to the end conversion process. However, other means for joining the central panel  12  to a container may be employed with the present invention. 
     The outer peripheral edge of the central panel  12  may be coined to add strength to can end  10 . Coining is the work hardening of metal between tools. The metal is typically compressed between a pair of tools, generally an upper and lower tool. 
     The central panel wall  12  has a displaceable tear panel  20  defined by a curvilinear frangible score  22  with an adjacent anti-fracture score  24  on the tear panel  20 , and a non-frangible hinge segment  26 . The hinge segment  26  is defined by a generally straight line between a first end and a second end of the frangible score  22 . The tear panel  20  of the central panel  12  may be opened, that is the frangible score  22  may be severed and the tear panel  20  displaced at an angular orientation relative to the remaining portion of the central panel  12 , while the tear panel  20  remains hingedly connected to the central panel  12  through the hinge segment  26 . In this opening operation, the tear panel  20  is displaced at an angular deflection, as it is opened by being displaced away from the plane of the panel  12 . 
     The frangible score  22  and the second groove or anti-fracture score  24  are formed using conventional-type of scoring operation during the can end forming process, using tools including an upper (public side) die with a score knife and a lower (product side) die with an anvil surface. 
     The frangible score  22  includes a length defined by a thickened portion of the residual. This length is often referred to as a check slot region. The check slot causes the propagation of the fracture of the frangible score  22  to slow naturally as the fracture reaches the check slot region. This allows the container to vent safely before the fracture of the frangible score  22  continues. 
     A deboss panel  50  is formed in the public side  34  of the central panel  12 . The deboss panel  50  is formed in the central panel  12  using conventional die-forming techniques. 
     The end member  10  described herein is used to produce a lightweight closure, for example from an 0.0084 inch thick aluminum stock for attachment to a container necked to a 202 (2.125 inches) or smaller open end. Accordingly, a diameter A of the can end  10  is typically about 2.340 inches, and diameter B of the center panel  12  is typically less than 2.340 inches. Preferably, the diameter B of the center panel  12  is less 1.500 to 2.340 inches; more preferably, the diameter B is the less than 1.90 inches; and most preferably the diameter B is about 1.880 inches, or any range or combination of ranges therein. It should be understood that these values are merely examples. The invention disclosed herein could be applied to any can end size, including but not limited to 200, 206, and 209 end members. End members  10  of the present invention are generally manufactured using a multi-stage reforming method. 
     Referring still to  FIGS. 1 and 2 , an end member  10  of the present invention includes a means for joining the chuckwall  15  to the center panel  12  as a countersink  16 , also called an annular reinforcing or anti-peaking bead. The countersink  16  has an inner wall  52  integrally connected to the peripheral edge of the center panel  12  through an annular arcuate segment. Accordingly, the inner wall extends downwardly from the center panel  12 , generally at a very small angle from a vertical axis substantially perpendicular to the center panel  12  or parallel to a longitudinal axis  54 . This angle is generally between ±5 to 10 degrees, or any range or combination of ranges therein. 
     The inner wall  52  is joined to an outer wall  56  through an annular arcuate portion, the lower extent of which defines a baseline. The outer wall is angled outwardly relative to the vertical axis. The angle is generally on the order of 0 to 30 degrees, more preferably 15 to 30 degrees, and most preferably 20 to 30 degrees, or any range or combination of ranges therein. The outer wall  56  is integral with the chuckwall  15 . 
     In  FIGS. 3 and 4 , the can end  10  is shown with a fold  60  joining the chuckwall  15  to the center panel  12  rather than a countersink. 
     The Tab 
     Referring to  FIGS. 1 and 3 , the end member  10  also has a non-detachable tab  70  secured or staked to the center panel  12  by a rivet  72 . The tab  10  is constructed of a rigid material, typically aluminum alloy metal, and is substantially flat, generally disposed along a common plane. The tab  70  has a lift end  74 , a central webbing  76 , and a nose portion  78 . The lift end  74  and the nose portion  78  are generally aligned along a central axis  79  passing through the rivet  72 . The rivet  72  is formed in the typical manner. 
     The user initiates opening of the end member  10  by lifting the lift end  74  of the tab  70 . This lifts the rivet  72  which causes the score groove  22  to fracture in a vent region which is located at least partially within the bounds of a coined region surrounding the rivet  72 . As the nose portion  78  presses against the tear panel  20 , the fracture of the score  22  propagates around the tear panel  20 , preferably in progression from the first end of the score  22  toward the second end of the score  22 . 
     Referring to  FIG. 7 , the central webbing  76  of the tab  70  has a rivet island  80  with an aperture  81  adapted for receiving the rivet  72  to secure the tab  70  to the center panel wall  12  of the can end  10 . The rivet island  80  is generally defined by hinge region  82  and a rivet island window  84  exposing a first exposed area of the center panel. The window  84  is preferably a curvilinear shaped opening or void region having a first end  84   a  and a second end  84   b . The hinge region  82  preferably appears as a tongue of the tab webbing  76  which joins the rivet island  80  to the remaining webbing  76 . The hinge region  82  has a hinge line between the first and second ends  84   a ,  84   b  of the window  84 , preferably defined as a straight line therebetween. 
     The window  84  has a first edge  88  defining the outer side of the curvilinear opening and a second edge  90  defining the inner side of the curvilinear opening. The window  84  is preferably formed by lancing the metal and subsequently bending back the metal on either or both sides of the lance to form a widened opening. The expansion of the lance by bending metal back, an operation called “wipe down,” causes a bend  94  of the metal along the edge of the window  84 , appearing as a fold or curl. Another practiced method of forming the window  84 , although likely to result in lesser rigidity and stress resistance, is to merely stamp out a blank of metal in the shape of the window  84 , without any bending of the edges of the window  84 . 
     The bend of metal in the ends of the window  84 , referred to henceforth as the curl  94  in the edges of the ends  84   a ,  84   b  of the window  84 , provides a collar in the edges, as a structural component to increase the strength of the metal in the ends  84   a ,  84   b  and to resist stresses and prevent tearing during use of the tab  70 . This added strength is primarily provided by the curl  94  providing an alteration in the direction of the metal, by bending the metal to a direction outside the planar path of the webbing region. With such alteration in the directional orientation of the metal in the ends  84   a ,  84   b , the metal in the region of the curl  94  has an increased resistance to the sheer forces on the metal when the tab  70  is used for opening the container end. It is also believed that added strength in the ends  84   a ,  84   b , is provided by the residual stress state of the metal in and around the curl  94 . 
     The nose  78  is preferably integral with a folded edge (curl)  96  of the outer periphery of the tab  70 . The lift end  74  of the tab  70  also has a folded edge (curl)  98 . The folded edge  96  of the nose  78  and the similar folded edge of the outer periphery of the lift end  74  have a bend of the metal and are adapted to provide strength of the tab  70  to resist stress from outside the plane. The tab  70  also has another void region or window, i.e. a finger hole  100 , having a perimeter  101  preferably being defined by a downwardly projecting inner folded, or curled, edge  102  of the central webbing  76  which provides a smooth inner edge of the finger hole  100  and strengthens the metal of the outer periphery of the finger hole  100 . The finger hole  100  is located between the lift end  74  and the window  84  to provide a second exposed area of the center panel  12 . 
     The window  84  and the finger hole  100  are separated by a narrow strip  104  of the central webbing  76 . Opposing longitudinal sides  106   a ,  106   b  of the narrow strip  104  extend from the widest segment of the finger hole  100  in a straight line to the widest segment of the window  84 . The opposing sides (dashed lines  106   a ,  106   b ) slightly converge from wider finger hole  100  inwardly to the window  84 . Opposing curvilinear transverse sides  107   a ,  107   b  of the narrow strip  104  comprise portions of the window  84  curl  94  and the finger hole  100  curled edge  102 , respectively. A portion  108  of the narrow strip  104  extends downwardly and approaches the public side  34  of the center panel  12 . This ensures that a height δ of the lift end  74  of the tab  70  above the public side  34  of the center panel  12  is maintained at a predetermined height. This portion of the narrow strip  104  is particularly advantageous to improve the accessibility of the lift end  74  if the tab  70 . Due to the relatively small area of the can end  10  and the center panel  12 , it is difficult for a user to access the lift end  74  with his or her finger. A can end  10  of the present invention typically has a small distance C between the lift end  74  of the tab  70  and the chuckwall  15 . (See  FIGS. 2 and 4 ). The magnitude of this distance C can be less than the magnitude of the height δ of the lift end  74  of the tab  70  above the public side  34  of the center panel  12 . The distance C is preferably less than 0.050 inches; more preferably, the distance C is less than 0.040 inches; and most preferably, the distance C is between 0.030 and 0.040 inches, or any range or combination of ranges therein. 
     The portion of the narrow strip  104  ensuring the height δ of the lift end  74  above the public side of the central panel  12  is preferably a portion of the window  84  curl  94  or the finger hole  100  curled edge  102 ; more preferably, the portion of the narrow strip  104  ensuring the height δ of the lift end  74  above the public side  34  of the central panel  12  is a portion of the window  84  curl  94  or the finger hole  100  curled edge  102  having a greater radius of curvature than remaining portions of the curls  94 ,  102 ; still more preferably, the portion of the narrow strip  104  ensuring the height δ of the lift end  74  above the public side  34  of the central panel  12  is a portion of the window  84  curl  94  or the finger hole  100  curled edge  102  located along the narrowest extent  110  of the narrow portion  104  where the spacing between the window  84  and the finger hole  100  is shortest; still more preferably, the portion of the narrow strip  104  ensuring the height δ of the lift end  74  above the public side  34  of the central panel  12  is a portion of the window  84  curl  94  or the finger hole  100  curled edge  102  located along the narrowest extent  110  and is adapted to engage the public side  34  of the center panel  12 ; and most preferably, the portion of the narrow strip  104  ensuring the height δ of the lift end  74  above the public side  34  of the central panel  12  is a portion of the finger hole  100  curled edge  102  located along the narrowest extent  110  and engages the public side  34  of the center panel  12 . Alternatively, any portion of the finger hole  100  curled edge  102  may be adapted to maintain the height δ. Furthermore, one of ordinary skill on the art would appreciate that any of the combinations could be combined without departing from the spirit of the invention. 
     As illustrated in  FIGS. 9-16 , the tab  70  is sometimes manufactured without a finger hole. In this case, print, such as promotional information, is provided in the area of the central webbing  76  where the finger hole is typically located. In these embodiments, a down bead or detent  114 , as it would appear in cross-section, may be provided to maintain the height δ at a predetermined level as shown in  FIGS. 10 and 16 . Alternatively, as shown in  FIGS. 9 and 14 , a second void region or window  116  can be formed in the webbing  76  between the first window  84  and the lift end  74 . The second window  116  is preferably formed in the same manner that the first window  84  is formed, i.e. by lancing the metal and a subsequent wipe down process of the metal on either or both sides of the lance to form a widened opening. The wipe down causes a bend  118  of the metal along the edge of the second window  116 , appearing as a fold or curl. A portion of the bend  118  provided for maintaining the height δ at a predetermined level as shown on  FIGS. 9 and 14 . 
     It should be understood that the portion of the tab  70  provided for maintaining the height δ at a predetermined level above the center panel  12  may not engage the center panel  12  until the container is pressurized, i.e. filled with a beverage to form a pressurized beverage containing vessel. As shown in  FIG. 17 , a container body  119  filled with a beverage is closed by an end member  10 , sealing a beverage within the vessel. At which point, an internal pressure causes an outwardly directed force on the center panel  12  to cause the center panel  12  to dome outwardly. As the center panel  12  becomes dome-shaped, the portion of the tab  70  provided for maintaining the height δ engages the center panel  12 . As the center panel  12  becomes larger, the doming is increased. Thus, a 209 end will undergo much more doming than a 200 end, and as the doming is increased, the length of the portion of the tab  70  provided for maintaining the height δ can be decreased. A prior art container is shown in  FIG. 18 . The height δ exhibited by the prior art end member is uncontrolled. Therefore, the height δ can vary greatly depending on the amount of doming, the size of the end member, etc. 
     It is desired to maintain the height δ at a predetermined level above the center panel  12 , typically greater than 0.050 inches. However, the height δ is preferably 0.050 to 0.100 inches; more preferably, the height δ is greater than 0.060 and/or less than or equal to 0.090 inches; and most preferably, the height δ is greater than 0.070 and/or less than or equal to 0.080 inches. The height δ may also be any range or combination of ranges set forth herein. It should be understood that depending on the length of the tab  70  and the size of the end  10 , e.g. 200, 202, 206, 209, etc. ends, the height δ can vary greatly, as can the distance C between the lift end  74  and the chuckwall  15 . It should also be understood that an objective of the present invention is to maintain the height δ at any desired predetermined level. Another objective is to maximize the height δ without having the tab  70  rise above the double seam when the container is pressurized to around 60 PSI. 
     As best illustrated in  FIG. 1 , the central webbing  76  preferably has a deboss bend  120 , a sloped region of the metal which results in a central deboss region of the central webbing  76  inward of the deboss bend  120 . This deboss region provides a lowered plane of the metal in the central webbing  76 . This structure of the tab central webbing  76  is adapted to lower the rivet island  80 , such that the lower surface of the rivet island  80  is positioned directly against the central panel  12  of the can end  10 , secured to the center panel  12  by the rivet  72  passing through the rivet island opening  81 , and staked thereto by stamping the top of the rivet  72 . The tab  70  is secured in this manner in a position whereby the nose  78  extends partially over the tear panel  20  of the center panel  20  and the hinge line of the tab  70  is generally aligned with the proximal edge of the tear panel  20 . 
     In operation, the tab  70  is lifted at the lift end  74 , operable by the user&#39;s finger applying a lifting force at the lift end  74 . Lifting the lift end  74  forces the nose  78  of the tab  70  downward, to force the nose  78  against the tear panel  20  of the end  10 . Because the rivet  72  maintains the rivet island  80  against the center panel  12 , the tab  70  remains attached to the end  10  and bends across the hinge line  86  of the tongue of the central webbing region  76 . The collar of each terminal end  84   a ,  84   b  of the window provides resistance to tearing of the metal across the hinge line  86  during use of the tab  70 . 
     Several alternative embodiments have been described and illustrated. A person ordinary skilled in the art would appreciate that the features of the individual embodiments, for example, variations of the countersink and folded portions, can be applied in combination with any of the tab variations to arrive at a suitable can end member. A person ordinary skilled in the art would further appreciate that any of the embodiments of the tab could be provided in any combination with the folded transition wall and/or the chuckwall variations disclosed herein. Further, the terms “first,” “second,” “upper,” “lower,” etc. are used for illustrative purposes only and are not intended to limit the embodiments in any way, and the term “plurality” if used herein is intended to indicate any number greater than one, either disjunctively or conjunctively as necessary, up to an infinite number. As used herein, the word “maintain” is defined as controlling or keeping in an existing or desired state, such as keeping the height δ greater than 0.050. As used herein, the word “predetermined” means to determine beforehand. 
     While specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention and the scope of protection is only limited by the scope of the accompanying claims.