Shell with expandable bubble and tooling therefor

Abstract

A can end including a central panel with an expandable bubble disposed thereon is provided. The use of an expandable bubble allows for an expandable rivet button and thereafter an expandable rivet that has an enhanced overlap of a tab body. Such an expandable rivet allows for the use of a metal sheet with a thinner base thickness.

What is claimed is: 
     
         1 . A can end comprising:
 a central panel, said central panel having a base thickness; and   an expandable bubble disposed on said central panel.   
     
     
         2 . The can end of  claim 1  wherein said central panel has a thickness of between about 0.0080 inch and about 0.0070 inch. 
     
     
         3 . The can end of  claim 2  wherein said central panel has a thickness of about 0.0078 inch. 
     
     
         4 . The can end of  claim 1  wherein:
 said expandable bubble includes a head and a periphery; 
 said expandable bubble head has a thickness of between about 0.0070 inch and 0.0079 inch; 
 said expandable bubble has a height of between about 0.0750 inch and about 0.0880 inch; and 
 and said expandable bubble periphery is one of an enhanced coined periphery or expanded coined periphery. 
 
     
     
         5 . The can end of  claim 4  wherein:
 said expandable bubble head has a thickness of about 0.0076 inch; and 
 said expandable bubble has a height of about 0.0859 inch. 
 
     
     
         6 . The can end of  claim 4  wherein said central panel is made from aluminum and is sized for a beverage container. 
     
     
         7 . A press structured to form a shell from sheet material, said sheet material having a base thickness, said press comprising:
 a frame;   a number of press stations including a bubble station;   said bubble station including a bubble station upper tooling assembly and a bubble station lower tooling assembly;   said bubble station upper tooling assembly including a first bubble coining surface, said upper tooling assembly movably coupled to said frame;   said bubble station lower tooling assembly including a second bubble coining surface, said lower tooling assembly coupled to said frame;   said first bubble coining surface structured to move between a first position, wherein said first bubble coining surface is spaced from said second bubble coining surface, and a second position, wherein said first bubble coining surface is a coining distance from said second bubble coining surface;   said first bubble coining surface and said second bubble coining surface structured to engage a bubble portion of a sheet material disposed between said first bubble coining surface and said second bubble coining surface; and   wherein, when said first bubble coining surface and said second bubble coining surface are in said second position, said first bubble coining surface and said second coining bubble surface are structured to form an expandable bubble.   
     
     
         8 . The press of  claim 7  wherein:
 said bubble station upper tooling assembly includes a bubble station upper punch and a bubble station upper cap; 
 said bubble station upper punch including a body with an upper end and a lower end; 
 said first bubble coining surface disposed on said bubble station upper punch body lower end; and 
 said bubble station upper punch structured to move between a first position, wherein said bubble station upper punch is spaced from said bubble station lower tooling assembly, and a second position, wherein said bubble station upper punch is immediately adjacent said bubble station lower tooling assembly. 
 
     
     
         9 . The press of  claim 8  wherein:
 said bubble station lower tooling assembly includes a lower punch and a lower cap; 
 said bubble station lower punch including a body with an upper end and a lower end; 
 said second coining surface disposed on said bubble station lower punch body upper end; and 
 said bubble station upper punch body lower end structured to move between a first position, wherein said bubble station upper punch body lower end is spaced from said bubble station lower punch body upper end, and a second position, wherein said bubble station upper punch body lower end is immediately adjacent said bubble station lower punch body upper end. 
 
     
     
         10 . The press of  claim 9  wherein:
 said bubble station upper punch body lower end includes a rounded peripheral portion; 
 said bubble station upper punch body lower end peripheral portion includes an outer end and an inner end; 
 said bubble station upper punch body lower end peripheral portion inner end has a radius; 
 said bubble station lower tooling assembly lower cap includes an inner radial surface; 
 said bubble station lower tooling assembly lower cap inner radial surface has a radius; and 
 wherein said bubble station upper punch body lower end peripheral portion inner end radius is greater than said bubble station lower tooling assembly lower cap inner radial surface radius. 
 
     
     
         11 . The press of  claim 9  wherein said lower punch has an expandable bubble contour. 
     
     
         12 . The press of  claim 7  wherein:
 said bubble station upper tooling assembly and said bubble station lower tooling assembly are structured to form an expandable bubble with a head; 
 said bubble station upper tooling assembly and said bubble station lower tooling assembly are structured to form said bubble head with a thickness of between about 0.0070 inch and about 0.0079 inch; and 
 said bubble station upper tooling assembly and said bubble station lower tooling assembly are structured to form said bubble with a height of between about 0.0750 inch and about 0.0880 inch. 
 
     
     
         13 . The press of  claim 12  wherein:
 said bubble station upper tooling assembly and said bubble station lower tooling assembly are structured to form said bubble head with a thickness of about 0.0076 inch; and 
 said bubble station upper tooling assembly and said bubble station lower tooling assembly are structured to form said bubble with a height of about 0.0859 inch. 
 
     
     
         14 . A method of forming a shell with an expandable bubble comprising:
 providing a sheet material with a base thickness;   forming said sheet material into a shell;   forming an expandable bubble on said shell; and   performing finishing operations on said shell.   
     
     
         15 . The method of  claim 14  wherein forming an expandable bubble on said shell includes:
 forming said expandable bubble with a bubble head; 
 forming said bubble head with a thickness of between about 0.0073 inch and 0.0079 inch; and 
 forming said expandable bubble with a height of between about 0.070 inch and about 0.0095 inch. 
 
     
     
         16 . The method of  claim 15  wherein forming an expandable bubble on said shell includes:
 forming said expandable bubble head with a thickness of about 0.0076 inch; and 
 forming said expandable bubble with a height of about 0.0859 inch. 
 
     
     
         17 . The method of  claim 14  wherein providing a sheet material with a base thickness and forming said sheet material into a shell include:
 providing an aluminum sheet; and 
 forming a beverage container shell. 
 
     
     
         18 . The method of  claim 15  wherein performing finishing operations on said shell includes:
 forming said expandable bubble into an expandable rivet button; 
 providing a tab with a body, said tab body including a coupling opening; 
 positioning said tab over said expandable rivet button with said expandable rivet button extending through said tab coupling opening; 
 forming said expandable rivet button into an expandable rivet; and 
 wherein said expandable rivet has an enhanced overlap of said tab body.