Patent Publication Number: US-2013243549-A1

Title: Method of Forming a Can End Having a Moveable Portion

Description:
TECHNICAL FIELD 
     The present invention relates to a method and tooling for forming a can end. In particular the present invention relates to a method and tooling for forming a can end having enhanced openability. 
     BACKGROUND 
     In the field of metal packaging, “easy open” ends for metal cans are well known. Typically, an easy open can end includes a pull tab and an approximately planar panel having a score line defining an opening area. To open a can having an easy open can end, a user may lift a handle of the pull tab to initiate fracture of the score line, and a user may subsequently pull the tab to partially or fully remove a portion of the panel, thereby creating an opening through which a user may access the contents. 
     Typically, the gap between the pull tab handle and the can end panel is very small. This small gap may make it difficult for a user to grasp the pull tab, because there may not be enough clearance under the pull tab for a user to insert a finger. Therefore, typical easy open cans may be difficult for a user to open. 
     A can end that has a moveable portion disposed beneath a handle of its tab has been developed by Crown Cork &amp; Seal. This can end—known commercially as the Easylift™ can end—is disclosed in U.S. Application Ser. No. 11/613,909, the contents of which are incorporated by reference in their entirety. The Easylift™ can end has a moveable portion that is deformable from an upward position to a downward position. In the upward position, the can end is readily stackable for transportation (i.e. before being attached to a container body), but provides little or no clearance between the can end and the tab. When deformed into the downward position (typically after being attached to a can body), the deformed moveable portion then provides clearance between the tab and can end to enable a user to engage their fingers with the tab and open the can. 
     While the moveable portion may be deformed into a downward position using a mechanical force, ideally the downward position is achieved utilizing a pressure differential across the can end. For example, before the can end is attached to the can body, the can body is filled with a hot comestible product. After the can end is attached, the hot product cools down gradually and approaches ambient temperature. This lower temperature, as well as resulting steam that is trapped inside the container, may result in a low-pressure period. This reduced pressure inside the container may produce a downward force (i.e. vacuum) acting on the moveable portion to thereby deform the moveable portion into a downward position without the use of a mechanical panel pusher. 
     Because it is ideal to deform the moveable portion into a downward position utilizing a pressure differential across the can end, there is a need for improved can ends and methods for manufacturing can ends having such capabilities. 
     SUMMARY 
     Methods for producing a can end having a moveable portion disposed beneath a tab are disclosed. In one embodiment, a can end having a center panel may be formed. A moveable portion that is moveable between an upward position and a downward position may be formed in the center panel. The moveable portion may be in the downward position after it is formed. The can end may then be restrained by a restraining tool such that a portion of the center panel that is adjacent to the moveable portion is unrestrained. While the can end is restrained, the moveable portion may be moved into the upward position. 
     In one embodiment the can end may be restrained with a restraining tool having an upper tool and a lower tool. The upper tool may press against an upper surface of the center panel and the lower tool may press against a bottom surface of the center panel. When the restraining tool is restraining the can end, the upper tool may be spaced apart from the portion of the center panel that is adjacent to the moveable portion. 
     In one embodiment the restraining tool may include an upper tool and a corresponding lower tool. The upper tool may have a first contact surface for contacting a top surface of the can end. The lower tool may have a protrusion and a second contact surface for contacting a bottom surface of the can end. The first and second contact surfaces may press against the can end to thereby restrain the can end. The portion of the center panel that is adjacent to the moveable portion of the center panel may be spaced apart from the upper tool when the can end is restrained by the upper and lower tools. While the can end is restrained, the protrusion may contact an underside of the moveable portion to thereby move the moveable portion from the downward position to the upward position. 
     These and various other advantages and features are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages, and the objects obtained by its use, reference should be made to the drawings which form a further part hereof, and to the accompanying descriptive matter, in which there are illustrated and described preferred embodiments of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top view depicting an embodiment of a can end having a moveable portion; 
         FIG. 2A  is a cross sectional view of the can end shown in  FIG. 1  with the moveable portion in an upward position; 
         FIG. 2B  is a cross sectional view of the can end shown in  FIG. 1  with the moveable portion in a downward position; 
         FIG. 3A  is a top view depicting a can end after the can end has been formed in a first operation; 
         FIG. 3B  is a top view depicting the can end of  FIG. 3A  after the can end has been formed in a second operation; 
         FIG. 3C  is a top view depicting the can end of  FIG. 3B  after the can end has been formed in a third operation; 
         FIG. 3D  is a top view depicting the can end of  FIG. 3C  after the can end has been formed in a fourth operation; 
         FIG. 3E  is a top view depicting the can end of  FIG. 3D  after a tab has been attached to the can end; 
         FIG. 4  is a schematic depicting a cross section of a restraining tool having an upper tool and a lower tool that are used during the fourth operation; 
         FIG. 5  is a schematic depicting a cross section of another restraining tool having an upper tool and a lower tool that are used during the fourth operation; 
         FIG. 6  is a perspective view depicting an upper tool that may be used with the restraining tool shown in  FIG. 5 ; 
         FIG. 7A  is a perspective view depicting an embodiment of a first die of a lower tool that may be used with the restraining tool shown in  FIG. 5 ; and 
         FIG. 7B  is a perspective view depicting an embodiment of a second die of a lower tool that may be used with the restraining tool shown in  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     Preferred structures and methods for can end technology are described herein. An embodiment of a can end and tooling for manufacturing a can end that employ this technology are also described. Further, the present invention encompasses other can end designs not described herein. 
     Some can ends may have a moveable portion disposed beneath a tab of the can end. The moveable portion is moveable between an upward position and a downward position. Such can ends are preferably manufactured so that the moveable portions are in the upward position. By having the moveable portions in the upward position, the can ends may be more densely stacked for shipment. When the can ends are seamed onto container bodies to thereby form containers, the moveable portions may be moved to the downward position (either mechanically or by utilizing internal negative pressure) so that a gap may be formed underneath their respective tabs. These gaps may allow a user to more easily insert a finger under the pull tabs, to thereby provide enhanced openability of the containers. 
       FIG. 1  shows a can end  10  having a moveable portion  14 . As shown, can end  10  has a center panel  18  with a reinforcing bead  22  at its periphery. Reinforcing bead  22  extends upwardly into a wall  26 , with wall  26  extending radially outwards to form a seaming panel  30 . A circular score line  34  is formed in can end  10 , defining an openable panel portion  38  inwards of score line  34 . Score line  34  (once severed) defines an aperture through which a product may be dispensed, with openable panel portion  38  being completely detachable from can end  10 . Beading  42  may be provided on center panel  18  for the purpose of strengthening center panel  18 . 
     A tab  46  is attached to center panel  18  by a rivet  50 . A first end of tab  46  is provided with a nose portion  54  disposed adjacent to score line  34 . The opposite end of tab  46  is provided with a handle portion  58  in the form of a ring. 
     As shown in  FIGS. 1 ,  2 A and  2 B, moveable portion  14  may be formed in a recessed portion  62  of center panel  18  and may include a downwardly inclined annular step  66  at its periphery. As shown in  FIGS. 2A and 2B , moveable portion  14  can revert between an upward position as shown in  FIG. 2A  and a downward position as shown in  FIG. 2B . 
     Typically can ends  10  are transported between different sites for later fixing to a can body (i.e. where a filler attaches the can end to the can body). Preferably, moveable portion  14  is in the upward position as shown in  FIG. 2A  during transport. When in the upward position, moveable portion  14  may have a convex profile that defines a recess  70  on the bottom side of center panel  18 . Thus, can ends  10  may be most efficiently stacked when moveable portion  14  is in the upward position, because recess  70  provides space for the tab of an underlying can end. 
     Once a can body is filled with a product, can end  10  is seamed onto the can body. After seaming, moveable portion  14  may revert back to the downward position. In order to move moveable portion  14  into the downward position, a force may be applied, generally in a downward direction, to moveable portion  14 . The force preferably arises from a pressure differential across can end  10 , where the pressure on the upper side of can end  10  (outside the container) is higher than the pressure on the lower side of can end  10  (inside the container). In other embodiments, the force may arise from a mechanical force applied to the upper side of moveable portion  14 . 
     When in the downward position as shown in  FIG. 2B , moveable portion  14  may have a concave profile that results in a gap Ah between handle portion  58  and moveable portion  14 . It is intended that a consumer should receive the container with moveable portion  14  in the downward position, because this maximizes tab access and consequently, ease of opening. The presence of annular step  66  may increase the force required for moveable portion  14  to pop-up back to the upward position. That is, annular step  66  may provide assurance against popping-up of moveable portion  14  even when the container is subjected to impacts with adjacent containers or other objects, or transported at high altitudes. In this way, the annular step  66  helps to maintain adequate finger access under the tab  46  for a container incorporating such a can end  10 . 
     In use, a consumer would engage their fingers with handle portion  58  to first lever tab  46  upwardly about rivet  50  to cause nose portion  54  to initiate rupture of score line  34 . Thereafter, the consumer may pull back on tab  46  to propagate tearing of the remainder of score line  34  and cause removal of openable panel portion  38  from can end  10 . 
     Can end  10  may be formed of any material such as aluminum or steel. For example, can end  10  may be formed of 0.21 mm gauge DR550N material.  FIGS. 3A-3E  show can end  10  after each of its forming operations. 
     As shown in  FIG. 3A , after a first forming operation, can end  10  includes center panel  18  with reinforcing bead  22  at its periphery. As shown, reinforcing bead  22  extends upwardly into wall  26 , with wall  26  extending radially outwards to form seaming panel  30 . At this stage, center panel  18  may be generally planar. 
     As shown in  FIG. 3B , after a second forming operation, score line  34  is formed in center panel  18  proximate to reinforcing bead  22 . 
     As shown in  FIG. 3C , after a third forming operation, moveable portion  14  and beading  42  are formed in center panel  18 . Typically, moveable portion  14  is formed in the downward position as shown in  FIG. 2B . 
     However, because can end  10  is typically transported with moveable portion  14  in the upward position, a fourth operation may be utilized to move moveable portion  14  into the upward position. In that regard, as shown in  FIG. 3D , moveable portion  14  is moved into the upward position during the fourth operation. Furthermore, additional beading  76  may be formed in center panel  18  during this operation. As shown, beading  76  may be formed proximate to score line  34  and rivet  50 . 
     As shown in  FIG. 3E , after a fifth operation, tab  46  is attached to center panel  18 . As shown, tab  46  may be attached with rivet  50  such that handle portion  58  is located above moveable portion  14 . During a sixth operation, burs formed on tab  46  may be removed. 
     During the fourth operation shown in  FIG. 3D , in which moveable portion  14  is moved into the upward position, can end  10  is restrained by a restraining tool. Depending on the restraining tool that is used and the manner in which it restrains the center panel  18  of can end  10 , the can end may have different operating parameters. That is, the metal may be stretched differently during the fourth operation to thereby create an end that operates differently under similar conditions.  FIGS. 4 and 5  depict two different restraining tools that may be used during the fourth forming operation of can end  10 . 
     As shown in  FIG. 4 , a restraining tool  80  includes an upper tool  84  and a lower tool  88 . As shown, can end  10  may be restrained between upper tool  84  and lower tool  88 . As can end  10  is restrained, moveable portion  14  formed in center panel  18  is moved to its upward position. 
     Upper tool  84  includes a first contact surface  94 , a second contact surface  98  and a recess  102 . First contact surface  94  and second contact surface  98  press against an upper surface of center panel  18  of can end  10 . As shown, second contact surface  98  extends further down than first contact surface  94  and contacts the recessed portion  62  of center panel  18 , including the portion of center panel  18  directly adjacent to moveable portion  14 . Accordingly, when moveable portion  14  is being moved into its upward position, a hinge  106  is created at a point directly adjacent to moveable portion  14 . 
     Lower tool  88  includes a first die  108  and a second die  110 . First die  108  includes a first contact surface  114 , a second contact surface  118  and a recess  120 . First contact surface  114  and second contact surface  118  press against a bottom surface of center panel  18  of can end  10 . As shown, second contact surface  118  is lower than first contact surface  114  and contacts a portion of the recessed portion  62  of center panel  18 . 
     Second die  110  is positioned in recess  120  of first die  108 . As shown, second die  110  includes a protrusion  122 . While can end  10  is being restrained by the respective contact surfaces  94 ,  98 ,  114 ,  118  of the upper tool  84  and lower tool  88 , protrusion  122  contacts an underside of moveable portion  14  to thereby move moveable portion  14  into an upward position. Recess  102  defined by upper tool  84  provides clearance for moveable portion  14  when it is in its upward position. 
     The can end  10  produced using restraining tool  80  contains certain operating parameters. For example, once this can end  10  is seamed onto a can body, a pressure of approximately 600 mbar may be required to move moveable portion  14  into its downward position. Furthermore, once in the downward position a pressure of approximately 600 mbar may be required to move moveable portion  14  back into its upward position. 
       FIG. 5  depicts another restraining tool that may be used during the fourth operation. The restraining tool of  FIG. 5  differs in its mode of operation to that of  FIG. 4  in restraining the center panel  18  at a location which is further laterally outward from the moveable portion  14  to that of  FIG. 4 . As shown, a restraining tool  180  includes an upper tool  184  and a lower tool  188 . As shown, can end  10  may be restrained between upper tool  184  and lower tool  188 . As can end  10  is restrained, moveable portion  14  formed in center panel  18  is moved to its upward position. 
     Upper tool  184  includes a first contact surface  194  and a recess  202 . First contact surface  194  presses against an upper surface of center panel  18  of can end  10 . Compared to the restraining tool  80  of  FIG. 4 , the upper tool  184  of restraining tool  180  in  FIG. 5  restrains the center panel  18  wholly laterally outward of the recessed portion  62  of the center panel. In effect, when using the restraining tool  180  during the fourth operation to move the moveable portion  14  into its upward position, the center panel  18  is less restrained than when using restraining tool  80 . When moveable portion  14  is being moved into its upward position using restraining tool  180 , a hinge  206  is created at a point radially outward from moveable portion  14 . 
     Lower tool  188  includes a first die  208  and a second die  210 . First die  208  includes a first contact surface  214 , a second contact surface  218  and a recess  220 . First contact surface  214  and second contact surface  218  press against a bottom surface of center panel  18  of can end  10 . As shown, second contact surface  218  is lower than first contact surface  214  and contacts a portion of the recessed portion  62  of center panel  18 . 
     Second die  210  is positioned in recess  220  of first die  208 . As shown, second die  210  includes a protrusion  222 . While can end  10  is being restrained, protrusion  222  contacts an underside of moveable portion  14  to thereby move moveable portion  14  into an upward position. Recess  202  defined by upper tool  184  provides clearance for moveable portion  14  when it is in its upward position. 
     The can end  10  produced using restraining tool  180  contains certain operating parameters that may differ from the operating parameters of the can end produced using restraining tool  80 . For example, once this can end  10  is seamed onto a can body, a pressure of approximately 300 mbar may be required to move moveable portion  14  into its downward position to thereby provide finger access under the tab. Furthermore, once in the downward position, a pressure of approximately 600 mbar may be required to move moveable portion  14  back into its upward position. By producing a can end that only requires approximately 300 mbar to move its moveable portion into a downward position, the potential for sufficient vacuum to cause pop-down without the need for a mechanical panel pusher is increased. Accordingly, the internal negative pressure created by the hot contents of the container may be more efficiently utilized to move the moveable portion into its downward position. This therefore demonstrates a benefit of the reduced restraint provided by using restraining tool  180 , as it has the increased potential to avoid the use of a mechanical pusher to move the moveable portion into the downward position to provide finger access under the tab. Examples of methods for using internal negative pressure of a container to move a moveable portion of a can end into its downward position are disclosed in U.S. provisional application No. 61/113,490 titled “Method of Assembling An Easy Open Can End” the contents of which are incorporated by reference in their entirety. 
     It should be understood that different pressures for moving the moveable portion into its downward position and for moving the moveable portion into its upward position may be required, depending on many factors such as the contents of the can, the manufacturer, and materials used. Regardless, can ends produced using restraining tool  180  may increase the possibility of moving the moveable portion into the downward position without a mechanical pusher. Furthermore, can ends produced using restraining tool  180  are capable of being seamed onto can bodies in high speed seaming operations. 
       FIGS. 6 ,  7 A and  7 B disclose example upper and lower tools that may be used for restraining tool  180 . Therefore, the upper tool shown in  FIG. 6  and the lower tool shown in  FIGS. 7A and 7B  will be capable of moving the moveable portion of a can end into an upward position while not restraining the portion of the center panel that is adjacent to the moveable portion. 
     As shown in  FIG. 6 , an upper tool  250  includes a first contact surface  254  and a recess  258 . As shown, recess  258  may be cylindrical and may be surrounded by first contact surface  254 . In other words, first contact surface  254  may extend from a peripheral edge of upper tool  250  to recess  258 . 
       FIG. 7A  shows a first die  270  of a lower tool and  FIG. 7B  shows a second die  272  of a lower tool. As shown in  FIG. 7A , first die  270  includes a first contact surface  274 , a second contact surface  278  and a recess  282 . First contact surface  274  may be defined by the upper most surface of first die  270  and second contact surface may be defined by a surface of a second recess  288  formed in first die  270 . Second recess  288  may be shaped to receive a recessed portion of a can end  10  so that can end  10  is not damaged during the fourth forming operation. Recess  282  may be formed in second recess  288  and may be shaped to receive or otherwise hold second die  272 . 
     As shown in  FIG. 7B , second die  272  may be shaped to fit in recess  282  of first die  270  and includes a protrusion  296 . When second die  272  is received by recess  282  of first die  270 , protrusion  296  is adapted to contact a bottom surface of a moveable portion of a can end. 
     The foregoing description is provided for the purpose of explanation and is not to be construed as limiting the invention. While the invention has been described with reference to preferred embodiments or preferred methods, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Furthermore, although the invention has been described herein with reference to particular structure, methods, and embodiments, the invention is not intended to be limited to the particulars disclosed herein, as the invention extends to all structures, methods and uses that are within the scope of the appended claims. Those skilled in the relevant art, having the benefit of the teachings of this specification, may effect numerous modifications to the invention as described herein, and changes can be made without departing from the scope and spirit of the invention as defined by the appended claims. Furthermore, any features of one described embodiment can be applicable to the other embodiments described herein.