Abstract:
A full aperture beverage end has a center panel, a countersink surrounding the center panel, a main score arranged in proximity to the countersink to define a removable aperture panel and a vent score. The beverage end is adapted for use with products that are pressurized to over 30 psi (200 kPa) when opened, and during opening the vent score is adapted to sever first, controlling the pressure differential between the external surface and internal surface of the center panel, thereby allowing the main score to tear in a controlled and reliable manner.

Description:
CROSS-REFERENCE TO RELATED APPLICATION TECHNICAL FIELD 
     This application claims priority to European Patent Application EP09169559.3, filed Sep. 4, 2009, the contents of which are incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present invention relates generally to beverage cans and particularly to the size of the drinking aperture created in a beverage can end. 
     BACKGROUND 
     Conventional full aperture can ends include a score that extends about the major area of the end&#39;s center panel and defines a removable panel. A tab is attached to the removable panel by a rivet. The tab heel is lifted initially to rupture the score, and then the tab is pulled to propagate the score until the removable panel is fully detached from the remainder of the end. Typically, full aperture opening ends are seamed onto food can bodies by conventional means. 
     Full aperture food can ends are also typically designed to allow full product release of the foodstuff contained within the food can. Often, this foodstuff is packed under slight negative pressure. In applications in which the food can is under positive internal pressure, the internal pressures are relatively low and because the pressure&#39;s primary purpose is to maintain the structural rigidity of the food can, which is often relatively “thin-walled”. 
     The internal pressure in conventional beverage cans, such as for carbonated soft drinks or beer, typically is much higher than the internal pressures in food cans, resulting in concerns related to “blow-off” of the ends upon opening or when subjected to adverse handling. For these reasons, commercial beverage cans have ends defining a restricted aperture, which can be safely opened by a consumer. 
     U.S. Pat. No. 5,711,448, assigned to Reynolds Metals Company, describes a conventional “large opening end” (that is, and end having a large opening). The patent describes “standard size opening” of 0.5 square inches and a “larger opening” of 0.5 to 0.75 square inches, each of which represents a relatively small fraction of the center panel. 
     Full aperture beverage can ends have been sold in the past but had safety problems and have been withdrawn from the market. ‘Spiral scored’ ends were produced for Sapporo beer, where the can end was vented in its centre and then the score propagated to the edge of the can end panel and the around the periphery thereof. Venting was critical because the end was relatively large, 66 mm diameter with a 52 mm centre panel size. If the end was opened without being vented, the panel could explode and missile towards the consumer. Thus a vent was used to provide safe venting and release the internal pressure in the can before opening. However the resulting spiral geometry of the opened end panel was dangerous having several long exposed cut edges and for this reason, this can end configuration was withdrawn. 
     SUMMARY OF INVENTION 
     The present invention relates to a full aperture beverage can end that has a center panel and a countersink that surrounds the center panel. The can end further comprises a main score arranged in proximity to the countersink to define a removable aperture panel as well as a vent score. The can end is adapted for use with products that are pressurized to over 30 psi (200 kPa). During opening, the vent score is configured to sever before the main score. In this way, the pressure differential between the external surface and internal surface of the center panel reaches equilibrium gradually. This allows the main score to tear in a controlled and reliable manner. 
     The present invention may further comprise a tab attached to the center panel by a rivet. The tab functions to assist the user in opening the can end. Additionally the main score may have an outer wall proximate a lip of the end, an inner wall proximate the aperture panel, and a land at the base of the main score. The land has a thickness that is smaller proximate the main score outer wall than the land thickness proximate the main score inner wall. This configuration allows the land to remain affixed to the aperture panel after detachment of the aperture panel. 
     According to another aspect of the present invention, a full aperture beverage can having rated for internal pressure of over 30 psi (200 kPa) includes a can body and a can end. The can end includes a center panel, a countersink surrounding the center panel, a tab attached to the center panel by a rivet, a main score that defines a removable aperture panel, and a vent score formed in the aperture panel. The main score has an outer wall proximate a lip of the end, an inner wall proximate the aperture panel, and a land at the base of the main score. The land has a thickness that is smaller proximate the main score outer wall than the land thickness proximate the main score inner wall. Accordingly, the land remains affixed to the aperture panel after detachment of the aperture panel. 
     The can may also be rated for internal pressures of at least 70 psi, 85 psi, or 90 psi. Preferably, the centerline of the main score is located between 0.000 and 0.020 inches, more preferably between 0.000 inches and 0.010 inches, more preferably between 0.000 inches and 0.006 inches, more preferably between 0.000 inches and 0.004, and most preferably between 0.000 inches and 0.002 inches, from a center of a transition radius between the countersink and the center panel. 
     A nose of the tab in its rest state is radially inwardly spaced apart from an inner edge of the main score by between approximately 0.000 inches and 0.008 inches, more preferably between approximately 0.000 inches and 0.005 inches, measured horizontally. In its partially actuated state, in which the tab nose contacts the center panel, the nose of the tab is approximately between the centerline of the main score and 0.005 inches radially inboard from an inner edge of the main score—more preferably within 0.002 inches of an inner edge of the main score. 
     Among the benefits for consumers are that because the beverage can becomes more like a drinking glass, consumers can drink from the can from any orientation and the can contents can be sipped rather than poured into the mouth. Furthermore, the content of the can is visible after opening, showing the colour, level of carbonation, and head (with widgeted beers). 
     One of the benefits for fillers is that the cans may be sold at festivals and events, as they can no longer be used as missiles. The larger, full aperture ensures that once opened, the majority of the beverage does not remain in the can is thrown. Furthermore, sealed beverage cans are preferable to glasses as they can be freshly opened immediately upon serving and thus many drinks can be freshly served in the interval periods during events. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
         FIG. 1  shows a plan view of can having a beverage end (tab not shown) according to a first embodiment of the present invention; 
         FIG. 2  shows a 3-dimensional view of a container incorporating the beverage end according to the invention, including a tab in a vented position (after the vent score has been severed); 
         FIG. 3  shows a 3-dimensional view of the container and beverage end shown in  FIG. 2 , from a rear angle; 
         FIG. 4  shows a 3-dimensional view of the container and beverage end shown in  FIGS. 2 and 3  (from the same angle as shown in  FIG. 2 ) after the vent score has been broken and as the main score starts to sever; 
         FIG. 5  shows a 3-dimensional view of the container and beverage end shown in  FIGS. 2 and 3  (from the same angle as shown in  FIG. 3 ) after the vent score has been broken and as the main score starts to sever; 
         FIG. 6  shows a 3-dimensional view of the container and beverage end after the main score has completely severed allowing the aperture to be exposed and the aperture panel to be removed; 
         FIG. 7A  (Prior Art) is a cross sectional sketch showing a standard (symmetrical) score profile used on conventional beverage ends; 
         FIG. 7B  is a cross sectional sketch showing the (asymmetric) score profile used for the main score on ends according to the invention; 
         FIG. 8  is a cross section view of a portion of the can end according to the invention fixed to a can body; 
         FIG. 9  is a top view of the can shown in  FIG. 2 ; 
         FIG. 10A  is a cross section view of a can illustrating a can end with the removable aperture panel removed according to a second embodiment of the present invention; 
         FIG. 10B  is a cross section view of a can illustrating a can end with the removable aperture panel removed according to a third embodiment of the present invention; 
         FIG. 10C  is a cross section view of a can illustrating a can end with the removable aperture panel removed according to a fourth embodiment of the present invention; 
         FIG. 10D  is a cross section view of a can illustrating a can end with the removable aperture panel removed according to a fifth embodiment of the present invention 
         FIG. 11  is a top view of the can of  FIG. 2 , with the tab shown as transparent to illustrate the vent score; 
         FIG. 12  is a top view of a punch for forming the vent score shown in  FIG. 1 ; and 
         FIG. 13  is an enlarged view of a portion of the punch of  FIG. 11 . 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     A can assembly  10  includes a one-piece can body  12  and a can end  14  that are joined together at a seam  16 . Preferably, can body  12  and seam  16  are conventional according to commercial carbonated beverage standards. 
       FIG. 1  illustrates a first embodiment end  14  with the tab omitted for clarity. End  14 , preferably formed of 5000 series aluminum, includes an wall portion  20 , a countersink  22 , and a center panel  30 . The shell configuration (that is, the end without the tab, having the structure as it leaves the shell press) has a configuration, including wall  20 , countersink  22 , and center panel  30 , in the embodiment shown in  FIG. 1 , that preferably is a conventional SuperEnd® end as supplied by Crown Cork &amp; Seal in a commercially popular size, such as  202 ,  204 , or  206 . 
     Countersink  22  extends from the lower part of wall  20  and includes a curved bottom portion  24  and an inner wall  26  that extends up from bottom  24 . Inner wall  26 , in the first embodiment ( FIG. 1 ) has a straight portion that merges into center panel  30  via transition  28  having a radius R. The origin of radius R is point C, as best shown in  FIG. 8 . For embodiments having a curved transition that does not have a single radius and a single origin, averages may be used. 
     Center panel  30  includes a rivet  34 , a moustache score  46 , a main score  50 , and an anti-fracture score  52 . Rivet  34  preferably is conventional. A tab  36  is attached to center panel  30  by rivet  34 . Tab  36  preferably is a solid tab—that is, without an integral hinge. Center panel  30  preferably is approximately planar in its unseamed or unpressurized state. 
     Moustache score  46  is configured to enable venting of pressurized can assembly  10 . For internal pressures greater than 30 psi, the vent score described in co-pending U.S. patent application Ser. No. 12/796,072, the disclosure of which is incorporated herein by reference, is preferred. As tab  36  is lifted by its handle or heel  38 , moustache score  46  is designed to break before main score  50  to vent the internal pressure in can  10 . 
     Main score  50  extends about the periphery of center panel  30  and defines a removable aperture panel  54 . As shown in the Figures, tab  36  is attached to aperture panel  54 . As is conventional, anti-fracture score  52  is also located on aperture panel  54  radially inside of main score  50  to reduce stress and take up slack metal. Upon removal of aperture panel  54 , a lip  32  is left behind. Lip  32  is the portion of end  14  that extends radially inwardly from the inside edge of the seam  16 . Further, aperture panel  54  may include debosses and embosses, as explained more fully below. 
     The inventors have identified the importance of configuring end  14  in such a way that main score  50  is in a location on end  14  that is sufficiently stiff to promote initial rupture of score  50  upon initial actuation of tab  36 .  FIG. 8  is an enlarged view of a first embodiment of end  14  and illustrates the relationship between main score  50  and countersink  22 , which stiffens end  14  in the region of end  14 . 
     Preferably, the centerline of main score  50  is near countersink  22  at the location of contact between tab nose  40  and center panel  30  such that the structural stiffness of countersink  22  prevents excessive panel deflection to promote initial score fracture. For example, the horizontal distance between transition curve origin C and the vertical center of main score  50  may be as low as 0.000 inches (that is, falling on the same vertical axis). Preferably, the centerline of main score  50  does not extend radially outside of point C so that the main score does not interfere with the structural performance of countersink  22 . In the embodiment of  FIG. 1 , the centerline of main score  50  preferably is within approximately 0.020 inches, more preferably is within approximately 0.010 inches, more preferably approximately 0.0060 inches, more preferably approximately 0.004 inches, and even more preferably approximately 0.002 inches (measured horizontally) of point C to get the benefit of countersink stiffening. The upper limit of distance between the main score centerline and point C may also be determined by aesthetics or the functional aspects of drinking. Alternatively, main score  50  may be spaced apart from countersink  22  and preferably located near a structural stiffener, such as an emboss, deboss, or like ridge. The configuration and distance of the main score and countersink may be chosen according to parameters that will be understood by persons familiar with beverage can end engineering and design upon considering this specification. 
       FIG. 7A  illustrates a symmetrical score profile  130  currently used for the aperture score of conventional beverage ends. Symmetric score  130  has a generally trapezoidal shape that includes a pair of identical but oppositely oriented sidewalls  130   a  and  130   b  and a generally flat land  130   c . In practice, it is difficult to control or predict exactly where (in its cross section) score  130  severs. Land  130   c , when severed and extending at the base of either sidewall  130   a  or  130   b , makes the edge sharp. This edge is more likely to cut a user than the fillet. The fillet is the score sidewall from which land the score residual of land  130   c  breaks cleanly (that is, the part of the score sidewall to which no portion or an insignificant part of the score residual of land  130   c  remains attached). 
       FIG. 7B  illustrates the asymmetrical main score  50  used on the beverage end  14  according to an aspect of the present invention. Asymmetric main score  50  has a pair of sidewalls  51   x  and  51   y  that extend to two different depths X and Y relative to the top surface of center panel  30 . Main score  50  also has a land  56 . In this specification, the term “land” refers generally to top surface or width and the term “score residual” refers to the thickness. Ends of the land  56   x  and  56   y  (in cross section as shown in  FIG. 7B ) are defined as the points at which the land merges into or transitions into the score sidewalls  51   x  and  51   y . In its opened state, the thickness at land ends  56   x  and  56   y  have score residual thicknesses T a  and T b . 
     Thicknesses T-a and T-b may be chosen according to the desired parameters of end  14 , such as proximity of score  50  to countersink  22 , end thickness and material, desired pressure rating, tab configuration, and the like. For the embodiment shown in  FIG. 1 , the thickness of center panel  30  is between 0.0075 inches and 0.013 inches, the width of score  50  at its top is approximately 0.007 inches, the width of score land  56  is approximately between 0.001 inches and 0.003 inches. T-a is approximately between 0.002 inches and 0.004 inches and T-b is approximately between 0.0025 inches and 0.045 inches. The present invention is not limited to the particular dimensions provided in this specification unless expressly stated in the claims. Rather, the invention encompasses other dimensions in accordance with the broad disclosure of its inventive aspects. 
     The score residual at thinner end  56   x  of score land  56  tends to fracture more readily than that at thicker end  56   y . This tendency is an advantage in controlling the location of the fracture within main score  50 . In this regard, the cross sectional structure of score  50  is configured such that the score residual of land  130   c  remains attached to aperture panel  54  rather than to lip  32  (that is, because the score residual at land outer end  56   x  is thinner than that at land inner end  56   y ), therefore leaving lip  32  having a fillet configuration. 
     The inventors have found also that for a given score, the structure and operation of the tab affects the reliability and predictability of the main score fracture. In this regard, if tab nose  40  is too far from main score  50 , end  14  may fracture between main score  50  and anti-fracture score  52  or within anti-fracture score  52 , rather than solely in main score  50 . Measured upon actuation of tab  36  when tab nose  40  first contacts end  14  and before main score fracture, tab nose  40  preferably does not span across main score  50  to touch the outer score wall  51   x . Preferably, tab nose  40 , upon contact with end  14 , is at the centerline of main score  50  or on aperture panel  54  within 0.005 inches radially inboard of the inner edge  60  of main score  50  ( FIG. 7B ). More preferably, tab nose  40  is within 0.002 inches on either side of the inner edge  60 . 
     The location of tab nose  40  may also be measured with the tab in its at-rest state before actuation by a user. In this regard, tab nose  40  preferably is between approximately 0.000 inches and 0.008 inches from the inner edge  60  of main score  50 , and more preferably between 0.000 inches and 0.005 inches, as measured radially inwardly from edge  62 . The difference in location of tab nose  40  relative to main score  50  between its initial contact state and its at-rest state is to account for shunting during the tab actuation process. Tab  36  shunts forward in the end shown in  FIG. 1  during the actuation and opening process by about 0.003 inches mostly because of deflection of panel  30  near rivet  34  and opening of vent score  46 . The magnitude of tab nose shunting also depends on internal can pressure. In general, higher pressure creates shunting of a corresponding greater magnitude. For simplicity, the dimensions provided for tab nose location relative to main score  50  are measured with a microscope looking straight down on end  14 , as shown for example in  FIG. 9 . 
     The location of tab nose  40  relative to main score  50  may be chosen according to the design parameters of the particular end, such as main score configuration, tab design, vent score design, can internal pressure, and other factors that will be understood by persons familiar with can end engineering and design upon considering the present specification. 
       FIGS. 2 through 6  show different 3-dimensional views of the first embodiment beverage end  14  applied to a filled can  10  (product level not shown).  FIGS. 2 and 3  illustrate the operation of end  14 . A user first lifts heel  38  of tab  36 , which pivots around the rivet  34 . The force and moment applied to rivet  34 , and the corresponding local deflection of center panel  30 , severs the vent score  46  creating a vent hole  48  (see  FIG. 3 ). Preferably, vent score  46  is in the form of a flap such that internal pressure of the can causes the fracture of vent score  46  to rupture without arresting, thereby deflecting the flap to vent pressures of greater than 30 psi, such as 70 psi, 85 psi, and 90 psi and above. 
       FIGS. 11-13  illustrate the components of the end  14 . To aid in the description of center panel  30 , primary or center reference line P L  is defined as extending through the center  34   a  of rivet  34  and through the longitudinal centerline of tab  36 . For the vast majority of commercial tabs, primary reference line P L  will extend through the point of initial contact between the nose of tab  36  and its point of initial contact on the center panel. Transverse reference line T L  is defined as extending through the center of rivet  34  and perpendicular to the primary reference line P L . The plane defined by lines P L  and T L  is parallel to the plane defined by the top of the seam and parallel to center panel  30 , to the extent that center panel  30  defines a plane in its seamed or unseamed state. Primary reference line P L  divides can end  14  into a front portion on the side of the tab nose and a rear portion on the side of the tab heel. 
     Vent score  46  includes a central portion  42 , a pair or lateral portions  45   a  and  45   b , and a pair of side portions  49   a  and  49   b . As best shown in  FIG. 5 , central portion  42  of vent score  46  is rounded as it extends around the rear center portion of rivet  34 . Opposing ends of central portion  42  extend forward about the rivet toward transverse reference line T L . Ends of central portion  42  yield to corresponding inner ends of lateral portions  45   a  and  45   b  through transitions  43   a  and  43   b , which preferably are approximately straight and angled from primary reference line P L  by an angle B that is approximately 45 degrees. Lateral portions  45   a  and  45   b  extend generally laterally (that is, generally parallel to transverse reference line T L ) and outwardly relative to rivet  34 . Side portions  49   a  and  49   b  extend generally rearward from outer ends of lateral portions  45   a  and  45   b  through transitions  47   a  and  47   b . Side portions  49   a  and  49   b  end at terminations  53   a  and  53   b . The vent score terminations may be curved, curled, or angled relative to the side portions of the vent score, or they may simply be the ends of straight side walls, as shown in the figures. 
     Dimensional information of vent score  46  is provided with reference to the enlarged view of the tool  80  for forming the vent score in  FIG. 13 . Preferably, a portion of vent score  46  extends to (or approximately to) or forward of the transverse reference line T L  to promote movement or hinging of the tab and rivet. For example, lateral portions  45   a  and  45   b  preferably extend forward of transverse line T L  by a dimension D 1 . Preferably, D 1  is positive and between 0 and 0.050 inches, and more preferably between 0.010 inches and 0.032 inches. In the embodiment shown in the figures, D 1  is approximately 0.021 inches. 
     Side portions  49   a  and  49   b  are mutually spaced apart and extend rearwardly such that flap  57  creates sufficient area for venting. The vent hole is shown in  FIG. 3  as reference numeral  48 . In this regard, side portions  49   a  and  49   b  preferably extend rearwardly from transverse reference line T L  by a distance D 2  that preferably is between 0.15 and 0.4 inches, and more preferably is between 0.2 and 0.3 inches. In the embodiment shown in the figures, D 2  is 0.238 inches. The ends of side portion terminations  53   a  and  53   b  are spaced apart by a distance of between 0.5 inches and 1.0 inches and preferably between 0.6 and 0.8 inches. In the embodiment shown, the distance between  53   a  and  53   b  is 0.742 inches. 
     Vent score sides may be curved or straight, and oriented at any angle A, measured relative to primary reference line P L . For example, A may be approximately zero (that is, the vent score sides may be approximately parallel to primary reference line P-L), between +/−10 degrees, between +/−20 degrees, or between +/−30 degrees. In the embodiment shown in the figures, angle A is 5 degrees. Central portion  42  and lateral portions  45   a  and  45   b  may be shapes other than as shown in the figures. 
     As illustrated in  FIGS. 4 and 5 , the user then continues to lift the tab  36 , which causes the tab nose  40  to press on the center panel  30  close to the main score  50 , as described above. Tab nose  40  severs main score  50  at land outer end  56   x . The user then pulls up on the tab  36  to break the remainder of the main score  50 . Preferably, the fracture propagates around aperture panel  54  at land outer end  56   x  such that the score residual of land  56  is attached to aperture panel  54 . Lip  32  remains part of the can assembly  10  and ideally has the cross sectional structure of a fillet (that is, a cross-sectional structure wherein a significant portion of the score residual associated with land  56  does not remain attached). 
     Once the main score  50  has completely severed the resulting aperture panel  54  and it is discarded, a user can drink directly from opening  58 . 
       FIG. 8 , described above, shows the relative height and configuration of countersink  22  and the center panel  30 , and the relative positions of the main score  50  and the anti fracture score  52 . The present invention is not limited to the particular embodiment of the end shown in  FIG. 8 . For example,  FIGS. 10A ,  10 B,  10 C, and  10 D illustrate additional embodiments of end structures  14   a ,  14   b ,  14   c , and  14   d  on which the present invention may be employed. To describe the embodiments shown in  FIGS. 10A through 10D , reference numerals of the structure described above with respect to the first embodiment will be reused, but appended with a letter designation. 
     Each of ends  14   a ,  14 ,  14   c , and  14   d  are seamed onto a can body  12   a ,  12   b ,  12   c ,  12   d .  FIGS. 10A ,  10 B,  10 C, and  10 D illustrate the cans having the aperture panel removed and ready for a user to drink from. The main scores, aperture panels, tabs, and all parts of the aperture panels for end embodiments  14   a ,  14   b ,  14   c , and  14   d  are as described above for first embodiment can end  14 . 
     End  14   a  of  FIG. 10A  is a variation of the SuperEnd® beverage can end described with respect to the first embodiment end  14 . The location of the center C of the radius of transition wall  28   a    50  is illustrated in  FIG. 10A . 
     End  14   b  of  FIG. 10B  is cross sectional view of an end supplied commercially by Container Development Limited. End  14   c  of  FIG. 10C  is a cross sectional view of an end referred to as LOF supplied by Metal Container Corporation. Each of ends  14   b  and  14   c  have an inner wall portion  29   b  and  29   c , respectively, at the base of transition  28   b  and  28   c . The present invention encompasses locating main score  50   b ,  50   c  radially outside of transition radius center C-b and C-d such that the main score is located within portions  29   b  or  29   c.    
     End  14   d  of  FIG. 10D  is a cross sectional schematic view of a conventional B64 end. The location of the center C of the radius of transition wall  28   d  is illustrated in  FIG. 10D . 
     The present invention has been described with respect to particular embodiments, and it is understood that the present invention encompasses structure and function broader than the particular embodiments, even if labeled as preferred.