Abstract:
A metallic container end closure is provided which includes a channel or groove in a predetermined location in at least one of an inner panel wall, outer panel wall, or chuckwall, and which is formed by a shaping tool. An apparatus and method for spin-forming the end closure with the improved geometry is also provided herein.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a method and apparatus for utilizing a spin forming tool to form a distinct geometric shape in a container end closure which is adapted for interconnection to a container neck and which has improved strength and buckle resistance. 
     BACKGROUND OF THE INVENTION 
     Containers, and more specifically metallic beverage containers, are typically manufactured by interconnecting a beverage can end closure on a beverage container body. In some applications, an end closure may be interconnected on both a top side and a bottom side of a can body. More frequently, however, a beverage can end closure is interconnected on a top end of a beverage can body which is drawn and ironed from a flat sheet of blank material such as aluminum. Due to the potentially high internal pressures generated by carbonated beverages, both the beverage can body and the beverage can end closure are typically required to sustain internal pressures exceeding 90 psi without catastrophic and permanent deformation. Further, depending on various environmental conditions such as heat, over fill, high CO2 content, and vibration, the internal pressure in a typical beverage can may at times exceed 100 psi. Thus, beverage can bodies and end closures must be durable to withstand high internal pressures, yet manufactured with extremely thin and durable materials such as aluminum to decrease the overall cost of the manufacturing process and the weight of the finished product. 
     Accordingly, there exists a significant need for a durable beverage container end closure which can withstand the high internal pressures created by carbonated beverages, and the external forces applied during shipping, yet which is made from a durable, lightweight and extremely thin metallic material with a geometric configuration which reduces material requirements. Previous attempts have been made to provide beverage container end closures with unique geometric configurations to provide material savings and improve strength. One example of such an end closure is described in U.S. Pat. No. 6,065,634 To Crown Cork and Seal Technology Corporation, entitled “Can End and Method for Fixing the Same to a Can Body”. Other inventions known in the art have attempted to improve the strength of container end closures and save material costs by improving the geometry of the countersink region. Examples of these patents are U.S. Pat. Nos. 5,685,189 and 6,460,723 to Nguyen et al, which are incorporated herein in their entirety by reference. Another pending application which discloses other improved end closure geometry is disclosed in pending U.S. patent application Ser. No. 10/340,535, which was filed on Jan. 10, 2003 and is further incorporated herein in its entirety by reference. Finally, the assignee of the present application owns another pending application related to reforming and reprofiling a container bottom, which is disclosed in pending U.S. Pat. No 11/020,944 and which is further incorporated herein by reference in its entirety. 
     The following disclosure describes an improved container end closure which is adapted for interconnection to a container body and which has an improved countersink, chuck wall geometry, and unit depth which significantly saves material costs, yet can withstand significant internal pressures. 
     Previous methods and apparatus used to increase the strength of a container end closure have generally been attempted using traditional forming presses, which utilize a sequence of tooling operations in a reciprocating press to create a specific geometry. Unfortunately with the use of small gauge aluminum and other thin metallic materials, it has become increasingly difficult to form a preferred geometry without quality control issues as a result of the physical properties of the end closure and the difficulty of retaining a desired shape. Furthermore, when a thin metallic material is worked in a traditional forming press, certain portions of the end closure may be thinned, either from stretching, bending operations, commonly known as “coining”. When excessive thinning occurs, the overall strength and integrity of the end closure may be compromised. Further, it is practically impossible to form certain geometries with a typical die press. Thus, there is a significant need in the industry for a new method and apparatus for forming a preferred shape in an end closure, and which uses rollers and other mechanical devices which can form a preferred shape in the end closure without requiring traditional forming presses and the inherent problems related thereto. 
     Furthermore, new end closure geometries are needed which have distinct shapes and provide superior strength and buckle resistance when interconnected to pressurized containers. As previously mentioned these geometries are typically not feasible using traditional end closure manufacturing techniques. Thus, there is a significant need for new end closure geometries which have improved strength characteristics and which are capable of being formed with thin walled metallic materials. 
     SUMMARY OF THE INVENTION 
     It is thus one aspect of the present invention to provide an improved method and apparatus for forming one or more reinforcing beads or other geometric shapes in a container end closure. Thus, in one aspect of the present invention, one or more shaping rollers are utilized to spin-form a portion of an interior or exterior wall portion of a chuck wall or an end closure countersink to provide improved strength characteristics and potential material savings. As used herein, the term “spin-form” may also be referred to as “reform” or “reprofile” and may generally be defined as a process to alter the geometric profile of a container end closure. In one embodiment, a method for changing the geometry of a metal end closure is provided, comprising: 
     A method for creating a preferred geometry of a metallic end closure which is adapted for interconnection to a neck of a container, comprising: 
     a) providing a metallic end closure comprising a peripheral cover hook, a chuck-wall extending downwardly therefrom, a countersink having an outer panel wall interconnected to a lower end of the chuck wall, and an inner panel wall interconnected to a central panel; 
     b) providing a shaping tool which rotates around a central axis, said shaping tool in having an outer surface with a predetermined shape; 
     c) positioning said outer surface of said shaping tool in contact with at least one of the inner panel wall, the outer panel wall and the chuck wall, wherein a predetermined shape is created in said end closure when said shaping tool engages said metallic end closure. 
     In another aspect of the present invention the shaping rollers are interconnected to an apparatus which rotates about a given axis which allows the shaping rollers to be positioned against the end closure to create a preferred shape. Alternatively, the end closure is rotated about one or more shaping rollers, which are substantially stationary. Thus, it is another aspect of the present invention to provide an apparatus for forming a preferred geometry in a metallic end closure by utilizing a tool which rotates around a substantially stationary end closure, comprising: 
     a means for retaining said end closure in a substantially stationary position; 
     a container spin-forming assembly comprising a roller block aligned in opposing relationship to the end closure, said roller block having an outer annular edge and a leading surface; 
     a rotating means for rotating said spin-forming assembly; 
     a pair of reform rollers which project outwardly from said roller block leading surface and which are operably sized to engage an inner panel wall of the end closure of the container; and 
     a biasing means operably interconnected to said pair of reform rollers, wherein when a force is applied to an annular flange on said pair of reform rollers by the end closure, said reform rollers extend outwardly toward said outer annular edge of said roller block, wherein a preferred geometric profile is created on the inner panel wall of the end closure. 
     It is another aspect of the present invention to provide improved end closure geometries which can be obtained utilizing the aforementioned apparatus and method and which are generally not obtainable using commonly known die presses. In one embodiment, one or more inwardly or outwardly extending reinforcing beads are formed in the chuck wall or inner or outer panel walls of the countersink to create a desired shape in a container end closure. More specifically, a metallic end closure adapted for interconnection to a sidewall of a container body is provided, comprising: 
     a peripheral cover hook; 
     a chuck wall extending downwardly from said peripheral cover hook; 
     a countersink comprising an outer panel wall interconnected to a lower end of said chuck wall and an inner panel interconnected to a central panel; and 
     a channel with a predetermined geometric profile positioned in at least one of said inner panel or said outer panel of said countersink, wherein the distance between said inner panel wall and outer panel wall at said channel is less than the distance between the outer panel wall and the lower panel wall in a lower portion of the countersink. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front cross-sectional elevation view of one embodiment of the invention shown before reforming or spin-forming; 
         FIG. 2  is a front cross-sectional elevation view of the embodiment shown in  FIG. 1  and showing inside reforming wherein a channel is positioned on an inner panel wall; 
         FIG. 2A  is a front cross-sectional elevation view showing a variation of the reforming shown in  FIG. 2 ; 
         FIG. 3  is a cross-sectional front elevation view of an alternative embodiment of the present invention, wherein an outer panel wall is reformed; 
         FIG. 3A  is a cross-sectional front elevation view depicting a variation of the embodiment shown in  FIG. 3 ; 
         FIG. 4  is a cross-sectional front elevation view showing a shell end closure which has been reformed on both an inside panel wall and outside panel wall; 
         FIG. 5  is a front perspective view of one embodiment of the present invention showing the inner panel wall reformed; 
         FIG. 6  is a front perspective view of an alternative embodiment of the present invention showing an outer panel wall reformed; 
         FIG. 7  is a front perspective view of an alternative embodiment of the present invention wherein both the inner panel wall and outer panel wall have been reformed; 
         FIG. 8  is a front cross-sectional elevation view showing a container end closure after both the inner panel wall and outer panel wall have been reformed and further depicting a reforming assembly; 
         FIG. 9  is a cross-sectional front elevation view further showing the components of one embodiment of a reforming tool prior to positioning a channel in an inner panel wall of an end closure; 
         FIG. 10  is a cross-sectional front elevation view showing a container end closure positioned opposite a reforming tool and just prior to reforming; 
         FIG. 10A  is a front cross-sectional view of the embodiment shown in  FIG. 10A  and after a reforming channel has been positioned in an inner panel wall; 
         FIG. 11  is a top front perspective view of a container end closure positioned on top of a spin-forming assembly and depicting the reprofile rollers in operable contact with an outer panel wall of a container end closure; and 
         FIG. 12  is an alternative embodiment of the spin-forming assembly of  FIG. 11 , and depicting two interior reform rollers and four reprofile rollers. 
     
    
    
     For clarity, the following is a list of components generally shown in the drawings: 
     
       
         
               
               
             
               
               
             
           
               
                   
               
               
                 No. 
                 Components 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 2 
                 End closure 
               
               
                 4 
                 Central panel 
               
               
                 6 
                 Peripheral cover hook 
               
               
                 8 
                 Chuck wall 
               
               
                 10 
                 Countersink 
               
               
                 12 
                 Countersink inner panel wall 
               
               
                 14 
                 Countersink outer panel wall 
               
               
                 16 
                 Channel 
               
               
                 18 
                 Container 
               
               
                 20 
                 Container neck 
               
               
                 22 
                 Double seam 
               
               
                 24 
                 Panel radius 
               
               
                 26 
                 Inside reform radius 
               
               
                 28 
                 Outside reform radius 
               
               
                 30 
                 Reform gap 
               
               
                 32 
                 Spin forming assembly 
               
               
                 34 
                 Roller block 
               
               
                 36 
                 Reform Rollers 
               
               
                 38 
                 Roller block leading surface 
               
               
                 40 
                 Roller block central aperture 
               
               
                 42 
                 Mounting shaft 
               
               
                 44 
                 Reprofile rollers 
               
               
                   
               
             
          
         
       
     
     DETAILED DESCRIPTION 
     Referring now to  FIGS. 1 through 11 , various embodiments of the present invention are provided herein. More specifically,  FIG. 1  depicts a typical beverage container end closure shell shown before a reforming or “spin-forming” procedure has been performed. More specifically, the end closure  2  is generally comprised of a peripheral cover hook  6 , a chuck wall  8  which extends from the peripheral cover hook  6  and which is interconnected to a countersink  10  on a lower end. The countersink  10  is generally comprised of an inner panel wall  12  and an outer panel wall  14 , and wherein the inner panel wall  12  is interconnected to the central panel  4 . 
     Referring now to  FIG. 2 , the end closure of  FIG. 1  is shown after an inner panel wall reforming or spin-forming procedure has been performed. More specifically, after the positioning of the inside reforming tool, a channel  16  is formed in the inner panel wall of the countersink, thus changing the geometric profile and in this particular embodiment providing a channel radius of approximately 0.035 inches. As appreciated by one skilled in the art, the actual geometric configuration and/or size of the channel  16  is not critical to the present invention, but rather the novelty in one embodiment relates to the method of forming the channel  16  in the various geometries which can be obtained using this method which are impractical or impossible to perform in a typical die press. Based on these novel methods and the apparatus used for form these geometries, unique and novel end closure geometries can be formed which are not possible with typical die presses. In one embodiment, it is anticipated that the channel on either the inner panel wall  12  or outer panel wall  14  may have a radius of between about 0.005-0.035 inches. Referring now to  FIG. 2A , a slight variation of the geometry shown in  FIG. 2  is provided herein, and wherein the inner panel wall has a distinct shape positioned near a ***lowermost portion of the countersink, and which is entirely different than the embodiment shown in  FIG. 2 . 
     Referring now to  FIGS. 3 and 3A , an alternative embodiment of the present invention is provided herein, wherein the channel  16  is positioned on an outer panel wall of the countersink  10 .  FIG. 3A  represents a variation of the embodiment shown in  FIG. 3 , wherein the geometry is distinct and the channel  16  is not as pronounced as the embodiment shown in  FIG. 3 , and is positioned on a lower portion of the outer panel wall  16 . As further shown in  FIG. 3 , depending on the depth of the channel  16 , a reform gap  30  is created and which may have a dimension of between about 0.070-0.005 inches. Alternatively, the reform gap  30  may be eliminated altogether by creating a deep channel  16 . 
     Referring now to  FIG. 4 , an alternative embodiment of the present invention is provided herein, wherein both the inner panel wall  12  and outer panel wall  14  of the end closure  2  have been reformed to create a channel  16  which substantially oppose each other. Although in this embodiment a reform gap  30  is provided, as mentioned above, the channel on the inner panel wall and/or an outer panel wall may be deep enough to completely eliminate the gap  30 , and wherein the inner panel wall and outer panel are in contact with each other. In either embodiment, the diameter between the channels  16  is less than the diameter between the lowermost portion of the inner panel wall  12  and outer panel wall  14 . 
     Referring now to  FIGS. 5-7 , front perspective views of alternative embodiments of the present invention are provided herein. More specifically,  FIG. 5  is an embodiment showing an end closure  2  having a channel  16  positioned on the inner panel wall, while  FIG. 6  is a front cut-away perspective view showing the channel  16  positioned on the outer panel wall of the countersink  10 . Alternatively,  FIG. 7  is a cross-sectional front perspective view showing a channel  16  positioned on both the inner panel wall and the outer panel wall of the countersink  10 . 
     Referring now to  FIG. 8 , a cross-sectional front elevation view is provided which further depicts one embodiment of a dual reforming or spin-forming assembly  32  used to shape the end closure  2  to a desired geometric profile. As provided herein, the term “reform” or “spin-forming” may describe changing the geometric profile of the inner panel wall and/or outer panel wall or both, or the term “reprofiling” may additionally be used to describe the same process. In the drawing shown in  FIG. 8 , reform rollers  36  are shown after engagement with the inner panel wall of the countersink, while reprofile rollers  44  are shown just after engagement with the outer panel wall of the end closure  2  to create a preferred geometric shape  42 . In one embodiment, the reform rollers and reprofile rollers  44  are interconnected to a mounting shaft  42  and roller block assembly  32  which is used to support and spin the roller block end or reprofile rollers  44 . 
     Referring now to  FIG. 9 , an alternative embodiment of the present invention is shown wherein a roller block reforming and reprofiling assembly  32  is shown in an opposing position to an end closure  2 , and just prior to preparing a channel  16  in the inner panel wall of the countersink. As previously mentioned, depending on the geometric profile of the reform rollers  36 , the geometry and depth of the channel  16  can be any size and dimension depending on the performance criteria of the end closure  2 . 
     Referring now to  FIG. 10 and 10A , cross-sectional front elevation views are provided which show additional detail of the reform rollers  36  just prior to reforming in  FIG. 10  and after reforming in  FIG. 10A . As shown, after the reform roller  36  is placed in contact with the inner panel wall of the end closure  2 , a channel  16  is created between the central panel  4  and the countersink  10 . The end closure  2  is generally held stationary while the reform rollers  36  spin, although alternatively the reform rollers  36  can be held stationary while the end closure  2  is spun around an axis which is substantially parallel to the drive shaft of the reform assembly or perpendicular to the drive shaft assembly. 
     Referring now to  FIG. 11 , a front perspective view of one embodiment of the present invention is provided herein and which more clearly shows a roller block  34 , a roller block leading surface  38 , and the reprofile rollers  44  positioned in opposing relationship to the end closure  2 . Although  FIG. 11  depicts two reprofile rollers  44  interconnected to the roller block  34 , as appreciated by one skilled in the art, as few as one and as many as four or five reform rollers and/or reprofile or spin-form rollers can be used to provide a preferred geometry in a container end closure. 
       FIG. 12  depicts an alternative embodiment of a spin-rolling apparatus  32 , and which is shown without an end closure engaged thereto. As generally shown, the spin-forming apparatus in this embodiment includes two reform rollers  36  which are designed to move outwardly, and four reprofile rollers  44  which are generally designed to engage an outer panel wall of an end closure during a spin-forming operation. 
     While an effort has been made to describe various alternatives to the preferred embodiment, other alternatives will readily come to mind to those skilled in the art. Therefore, it should be understood that the invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. Present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not intended to be limited to the details given herein.