Abstract:
The present invention concerns a full aperture beverage end ( 14 ) having a centre panel ( 30 ), a countersink ( 22 ) surrounding the centre panel ( 30 ), a main score ( 50 ) arranged in proximity to the countersink ( 22 ) to define a removeable aperture panel ( 54 ) and a vent score ( 46 ). The beverage end ( 14 ) is adapted for use with products that are pressurised to over 30 psi (207 kPa) when opened, and during opening the vent score ( 46 ) is adapted to sever first, controlling the pressure differential between the external surface and internal surface of the centre panel ( 30 ), thereby allowing the main score ( 50 ) to tear in a controlled and reliable manner.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates generally to beverage cans and more particularly to the size of drinking aperture that is created in a beverage can end. There is increasing pressure by consumers to increase the size of such drinking apertures to increase the pleasure of drinking the beverage contained within the can, directly from the can. 
       BACKGROUND ART 
       [0002]    Conventional full aperture can ends include a score that extends around a major portion of the end&#39;s centre panel and defines a removable panel. A tab is attached to the removable panel by a rivet. The tab has a tail or handle end on one side of the rivet and a nose end on the opposite side of the rivet and the tab is positioned so that it&#39;s nose end lies adjacent to or touching the score. To open the can end, a user lifts the tail or handle end of the tab, which causes the tab to pivot about the rivet and presses the nose end adjacent to the score, propagating fracture of the score until the removable panel is detached from the remainder of the end. Typically, full aperture ends are attached to food can bodies by conventional seaming techniques. 
         [0003]    Full aperture food can ends are designed primarily to allow full product release of the foodstuff contained within the food can. Often, this foodstuff is packed under slight negative pressure. However, where pressurised food cans are proposed having positive internal pressure, the internal pressures are relatively low and merely determined by the internal pressure required to maintain the structural rigidity of the food can, which is often relatively “thin-walled”. 
         [0004]    In conventional beverage cans the beverage product, such as carbonated soft drinks or beer, typically is held under much higher pressures than the internal pressures in food cans, resulting in concerns related to “blow-off” of the ends upon initial opening by a user or when subjected to adverse handling. For these reasons, the conventional beverage can has an end defining a restricted aperture, which can be safely opened by a consumer. 
         [0005]    U.S. Pat. No. 5,711,448 A (REYNOLDS METALS CO) 27.01.1998 describes a conventional “large opening end” (that is an end having a relatively large opening), as currently used on some beverage cans. This patent describes a “standard size opening” of about 322.58 square mm (0.5 square inches) and a “larger opening” of about 322.58-483.87 square mm (0.5 to 0.75 square inches), which represents a relatively small fraction of the area of the centre panel. 
         [0006]    Full aperture beverage can ends have been sold in the past but these had serious safety issues and have now 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 then 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 would 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 very dangerous having several long exposed cut edges and for this reason, this can end configuration was withdrawn. 
         [0007]    Conventional beverage cans are often banned from being sold at festivals and events, because the restricted aperture prevents the contents of the can being from being discharged quickly if an opened beverage can is thrown. Thus, even if a conventional beverage can is opened at the point of sale at a festival or event, it may still provide a dangerous missile if thrown. 
       SUMMARY OF INVENTION 
       [0008]    Accordingly, the present invention provides a full aperture beverage end having a centre panel, a countersink surrounding the centre panel, a main score arranged in proximity to the countersink to define a removable aperture panel and a vent score, characterised in that the beverage end is adapted for use with products held under pressure exceeding 207 kPa (30 psi) 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 centre panel. In this way, the pressure differential between the external surface and the internal surface of the centre panel reaches equilibrium gently. This allows the main score to tear in a controlled and reliable manner. The can may also be rated for internal pressures of at least 483 kPa (70 psi), 586 kPa (85 psi), or 621 kPa (90 psi). 
         [0009]    Additionally, the main score may have an outer wall proximate the drinking lip of the end (once the aperture panel is removed), 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 ensures that the land remains affixed to the aperture panel after the aperture panel is removed. 
         [0010]    Preferably, the centreline of the main score is located between 0.000 and 0.508 mm (0.020 inches), more preferably between 0.000 and 0.254 mm (0.010 inches), more preferably between 0.000 and 0.152 mm (0.006 inches), more preferably between 0.000 and 0.102 mm (0.004 inches), and most preferably between 0.000 and 0.051 mm (0.002 inches) from a centre of a transition radius between the countersink and the centre panel. 
         [0011]    A nose of the tab in its rest state is radially inwardly spaced apart from an inner edge of the main score by between 0.000 and 0.203 mm (0.008 inches), more preferably between 0.000 and 0.127 mm (0.005 inches), measured horizontally. In its partially actuated state, in which the tab nose contacts the centre panel, the nose of the tab is approximately between the centreline of the main score and 0.127 mm (0.005 inches) radially inboard from an inner edge of the main score—more preferably within 0.051 mm (0.002 inches) of an inner edge of the main score. Among the benefits for consumers are that after opening, 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 contents of the can is visible after opening, showing the colour, level of carbonation, and head (with widgeted beers). 
         [0012]    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 if it 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 
         [0013]    The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
           [0014]      FIG. 1  shows a plan view of can having a beverage end (tab not shown) according to a first embodiment of the present invention; 
           [0015]      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); 
           [0016]      FIG. 3  shows a 3-dimensional view of the container and beverage end shown in  FIG. 2 , from a rear angle; 
           [0017]      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; 
           [0018]      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; 
           [0019]      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; 
           [0020]      FIG. 7A  (Prior Art) is a cross sectional sketch showing a standard (symmetrical) score profile used on conventional beverage ends; 
           [0021]      FIG. 7B  is a cross sectional sketch showing the (asymmetric) score profile used for the main score on ends according to the invention; 
           [0022]      FIG. 8  is a cross section view of a portion of the can end according to the invention fixed to a can body; 
           [0023]      FIG. 9  is a plan view of the can shown in  FIG. 2 ; 
           [0024]      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; 
           [0025]      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; 
           [0026]      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; and 
           [0027]      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. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0028]    A beverage can  10  includes a 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. 
         [0029]      FIG. 1  illustrates a first embodiment can end  14  with the tab omitted for clarity. Can end  14  includes a wall portion  20 , a countersink  22 , and a centre panel  30 . The shell configuration (that is, the can end without the tab as it leaves the shell press) has a configuration, including wall  20 , countersink  22 , and centre panel  30 . In the embodiment shown in  FIG. 1 , the can end is preferably a conventional SuperEnd® beverage can end as supplied by Crown Cork &amp; Seal. 
         [0030]    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 portion  24 . Inner wall  26  has a straight portion that merges into centre 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. 
         [0031]    Centre panel  30  includes a rivet  34 , a moustache score  46 , a main score  50 , and an anti-fracture score  52 . Rivet  34  is preferably conventional. A tab  36  is attached to centre panel  30  by rivet  34 . Tab  36  is preferably a solid tab—that is, without an integral hinge. Centre panel  30  is preferably substantially planar in its unseamed or unpressurized state. 
         [0032]    Moustache score  46  is configured to enable venting of the pressurized, filled can  10 . For internal pressures greater than 207 kPa (30 psi), the vent score described in the applicant&#39;s co-pending patent application no. U.S. Pat. No. 12/796,972 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 filled can  10 . 
         [0033]    Main score  50  extends about the periphery of centre panel  30  and defines a removable aperture panel  54 . As shown in  FIG. 6 , tab  36  is attached to the aperture panel  54 . A conventional anti-fracture score  52  is also located on aperture panel  54 , radially inside the main score  50  to reduce stress and take up slack metal as the main score  50  is severed. Upon removal of aperture panel  54 , a lip  32  is left behind. Lip  32  is the portion of can end  14  that protrudes radially inwardly from the inside edge of the seam  16 . Additionally, aperture panel  54  may include debosses and embosses, as explained more fully below. 
         [0034]    The inventors have identified the importance of configuring the can end  14  in such a way that main score  50  is in a location on the can end  14  that is sufficiently stiff to promote initial rupture of score  50  upon actuation of tab  36 .  FIG. 8  is an enlarged view of a first embodiment of the can end  14  and illustrates the relationship between the main score  50  and the transition  28  from the countersink  22  to the centre panel  30 , which stiffens the can end  14  in the region of the main score  50 . 
         [0035]    Preferably, the centreline of main score  50  is near the countersink  22  at the point where the tab nose  40  contacts the centre 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 centre of the main score  50  may be as low as 0.000 inches (i.e. falling on the same vertical axis). Preferably, the centreline of main score  50  does not extend radially outside point C so that the main score does not interfere with the structural performance of countersink  22 . In the embodiment of  FIG. 1 , the centreline of main score  50  is preferably within 0.508 mm (0.020 inches), more preferably within 0.254 mm (0.010 inches), more preferably 0.152 mm (0.0060 inches), more preferably 0.102 mm (0.004 inches), and even more preferably 0.051 mm (0.003 inches) measured horizontally of point C to get the benefit of countersink stiffening. The upper limit of distance between the main score centreline and point C may also be determined by aesthetics or the functional aspects of drinking. 
         [0036]    Alternatively, main score  50  may be spaced apart from the countersink  22 , but is 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. 
         [0037]      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). 
         [0038]      FIG. 7B  illustrates the asymmetrical main score  50  used in the can end  14  according to 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 external surface of centre panel  30 . Main score  50  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 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 . 
         [0039]    Thicknesses T a  and T b  may be chosen according to the desired parameters of can end  14 , such as proximity of main score  5  to the countersink  22 , thickness and material of the can end, desired pressure rating, tab configuration, and the like. For the embodiment shown in  FIG. 1 , the thickness of centre panel  30  is between 0.191 mm (0.0075 inches) and 0.330 mm (0.013 inches), the width of score 50 at its top is approximately 0.178 mm (0.007 inches), the width of score land 56 is between 0.025 mm (0.001 inches) and 0.076 mm (0.003 inches). T a  is between 0.051 mm (0.002 inches) and 0.102 mm (0.004 inches) and T b  is between 0.064 mm (0.0025 inches) and 1.143 mm (0.045 inches). 
         [0040]    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 smoother configuration. 
         [0041]    Also, the inventors have found 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 the main score  50  and the anti-fracture score  52  or within anti-fracture score  52 , rather than solely in the main score  50 . Measured upon actuation of tab  36 , when the tab nose  40  first contacts can end  14  (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 can end  14 , is at the centreline of main score  50  or on the aperture panel  54 , within 0.127 mm (0.005 inches) radially inboard of the inner edge  60  of main score  50  (see  FIG. 7B ). More preferably, tab nose  40  is within 0.051 mm (0.002 inches) radially inboard of the inner edge  60 . 
         [0042]    A user may also measure the location of tab nose  40  with the tab in its at-rest state before actuation. In this regard, tab nose  40  preferably is between 0.000 and 0.203 mm (0.008 inches) from the inner edge  60  of main score  50 , and more preferably between 0.000 and 0.127 mm (0.005 inches), as measured radially inwardly from edge  60 . The difference in location of tab nose  40  relative to main score  50  between its initial contact state and its at-rest state is due to 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 0.76 mm (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 is also dependant on internal can pressure. In general, a higher internal 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 . 
         [0043]    The location of the tab nose  40  relative to the main score  50  may be chosen according to the design parameters of the particular can end, for example main score configuration, tab design, vent score design, internal pressure, and other factors that will be understood by persons familiar with can end engineering and design upon considering the present specification. 
         [0044]      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 centre panel  30 , severs the vent score  46  creating a vent hole  48  (see  FIG. 3 ). Preferably, vent score  46  takes the form of a flap, such that internal pressure in the can causes the fracture of vent score  46  to rupture without arresting, thereby deflecting the flap to vent pressures of greater than 207 kPa (30 psi), such as 483 kPa (70 psi), 586 kPa (85 psi), and 621 kPa (90 psi) and above. 
         [0045]    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 centre panel  30  close to the main score  50 , as described above. Tab nose  40  severs main score  50  at the 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). 
         [0046]    Once the main score  50  has completely severed the resulting aperture panel  54  can be discarded and a user can drink directly from aperture  58 . 
         [0047]      FIG. 8 , described above, shows the relative height and configuration of countersink  22  and the centre 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. 
         [0048]    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 . 
         [0049]    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 centre C of the radius of transition wall  28   a  is illustrated in  FIG. 10A . 
         [0050]    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 centre Cb and Cc, such that the main score is located within portions  29   b  or  29   c.    
         [0051]    End  14   d  of  FIG. 10D  is a cross sectional schematic view of a conventional B64 end. The location of the centre C of the radius of transition wall  28   d  is illustrated in  FIG. 10D .