Method and apparatus for forming a can shell using a draw-stretch process

Abstract

A shell includes a body with a center panel, a countersink, a chuck wall, and a draw-stretched outer portion. The countersink has a base thickness. The outer portion has a reduced thickness. The shell countersink has substantially the same thickness as the sheet material prior to forming. In this configuration, the shell maintains the buckle resistance of a standard shell but uses less material.

What is claimed is: 
     
         1 . A shell comprising:
 a body including a center panel, a countersink, a chuck wall, a can fit radius, a crown radius, and a curl;   wherein said center panel and said countersink have a base thickness; and   wherein said body has a reduced volume.   
     
     
         2 . The shell of  claim 1  wherein said crown radius is a draw-stretched crown radius. 
     
     
         3 . The shell of  claim 2  wherein said shell body has one of a reduced profile or a maximum reduced profile 
     
     
         4 . The shell of  claim 1  wherein:
 said body is aluminum; 
 said countersink has a general thickness of between about 0.0104 inch and about 0.0078 inch; 
 said center panel has a general thickness of between about 0.0104 inch and about 0.0078 inch; and 
 said draw-stretched crown radius has a general thickness of between about 0.009 inch and about 0.0064 inch. 
 
     
     
         5 . The shell of  claim 4  wherein:
 said countersink has a general thickness of about 0.0086 inch; 
 said center panel has a general thickness of about 0.0086 inch; and 
 said crown radius has a general thickness of about 0.0076 inch. 
 
     
     
         6 . The shell of  claim 1  wherein:
 said body is steel; 
 said countersink has a general thickness of between about 0.0065 inch and about 0.0090 inch; 
 said center panel has a general thickness of between about 0.0065 inch and about 0.0090 inch; and 
 said crown radius has a general thickness of between about 0.0050 inch and about 0.0090 inch. 
 
     
     
         7 . The shell of  claim 6  wherein:
 said countersink has a general thickness of about 0.0080 inch; 
 said center panel has a general thickness of about 0.0080 inch; and 
 said crown radius has a general thickness of about 0.0080 inch. 
 
     
     
         8 . A press assembly structured to form a shell from a blank cut from sheet material, said sheet material having a base thickness, said press comprising:
 a frame;   a number of press stations including a first forming station;   said first forming station including an upper tooling assembly and a lower tooling assembly;   said first forming station upper tooling assembly structured to move between an upper, first position, wherein said first forming station upper tooling assembly is spaced from said first forming station lower tooling assembly, and a lower, second position, wherein said first forming station upper tooling assembly is immediately adjacent said first forming station lower tooling assembly;   wherein when said first forming station upper tooling assembly and said first forming station lower tooling assembly are structured to form a shell body including a center panel, a countersink, a chuck wall, and a crown radius;   wherein said first forming station upper tooling assembly and said first forming station lower tooling assembly are further structured to draw-stretch said crown radius to create a crown radius with a reduced thickness; and   wherein said first forming station upper tooling assembly and said first foil ling station lower tooling assembly are further structured to form said center panel and said countersink at said base thickness.   
     
     
         9 . The press assembly of  claim 8  wherein:
 said first forming station upper tooling assembly includes a blank & draw die punch, an upper piston, and a die center punch; 
 said first forming station lower tooling assembly includes an lower piston, a die core ring, and a panel punch; 
 said first forming station upper blank & draw die punch including an inner radius; 
 wherein said first forming station upper blank & draw die punch inner radius is a reduced radius; 
 said first forming station lower die core ring including an outer radius; and 
 wherein said first forming station lower die core ring outer radius is a diminished radius. 
 
     
     
         10 . The press assembly of  claim 9  wherein:
 said first forming station upper blank & draw die punch inner radius is about a 0.019 inch radius; and 
 said first forming station lower die core ring outer radius is about a 0.022 inch radius. 
 
     
     
         11 . The press assembly of  claim 9  wherein, when said upper tooling assembly is in said second position, said first forming station upper blank & draw die punch and said first forming station lower piston clamp said blank. 
     
     
         12 . The press assembly of  claim 11  wherein, when said upper tooling assembly is in said second position, said first forming station upper piston and said first forming station lower die core ring apply a force of between about 100 psi and about 600 psi to said blank. 
     
     
         13 . The press assembly of  claim 12  wherein, when said upper tooling assembly is in said second position, said first forming station upper piston and said first forming station lower die core ring apply a force of about 110 psi to said blank. 
     
     
         14 . A method of forming a shell comprising:
 providing a sheet material, said sheet material having a base thickness;   cutting a blank from said sheet material, said blank including a countersink portion, a chuck wall portion, and a crown radius portion;   providing a press assembly including a frame, a number of press stations including a first forming station, said first forming station including an upper tooling assembly and a lower tooling assembly, said first forming station upper tooling assembly structured to move between an upper, first position, wherein said first forming station upper tooling assembly is spaced from said first forming station lower tooling assembly, and a lower, second position, wherein said first forming station upper tooling assembly is immediately adjacent said first forming station lower tooling assembly, wherein when said first forming station upper tooling assembly and said first forming station lower tooling assembly are in said second position, said first forming station upper tooling assembly and said first forming station lower tooling assembly are structured to form a shell body including a center panel, a countersink, and a crown radius;   disposing said blank between said upper tooling assembly and said lower tooling assembly;   clamping said crown radius portion between said first forming station upper tooling assembly and said first forming station lower tooling assembly;   performing forming operations including:
 draw-stretching said crown radius portion to form a draw-stretched crown radius; 
 forming said countersink portion into a counter sink; and 
 draw-stretching said chuck wall portion into a draw-stretched chuck wall. 
   
     
     
         15 . The method of  claim 14  wherein said counter sink has a thickness corresponding to said sheet material base thickness. 
     
     
         16 . The method of  claim 13  wherein providing a press assembly includes:
 providing a first forming station upper tooling assembly that includes a blank & draw die punch, an upper piston, and a die center punch; 
 providing a first forming station lower tooling assembly that includes a lower piston, a die core ring, and a panel punch; 
 wherein said first forming station upper blank & draw die punch includes an inner radius; 
 wherein said first forming station upper blank & draw die punch inner radius is a reduced radius; 
 wherein said first forming station lower die core ring includes an outer radius; and 
 wherein said first forming station lower die core ring outer radius is a diminished radius. 
 
     
     
         17 . The method of  claim 16  wherein providing a press assembly includes:
 providing said first forming station upper blank & draw die punch wherein said inner radius is about a 0.019 inch radius; and 
 providing said first forming station lower die core ring wherein outer radius is about a 0.022 inch radius. 
 
     
     
         18 . The method of  claim 14  wherein draw-stretching said crown radius portion to form a draw-stretched crown radius include applying a force of between about 100 psi and about 600 psi to said blank. 
     
     
         19 . The method of  claim 18  wherein draw-stretching said crown radius portion to form a draw-stretched crown radius include applying a force of about 110 psi. 
     
     
         20 . The method of  claim 14  wherein cutting a blank from said sheet material includes cutting a blank with a reduced volume. 
     
     
         21 . The method of  claim 20  wherein performing forming operations includes forming said blank into a standard beverage shell.