Can manufacture using an annealing step

Abstract

A metal can body formed from a base stretching, drawing, and ironing process is formed of a material comprising aluminium. The process for forming the can includes a step of annealing the aluminium material.

1 . A method for manufacture of an aluminum cup, comprising the steps of:
 i. annealing an aluminum material;   ii. performing a stretching operation ( 30 ) on a cup ( 23 ) that is formed of the aluminum material and that has a sidewall ( 24 ) and an integral base ( 25 ), the stretching operation including:
 clamping ( 36 ,  37 ) an annular region ( 26 ) on either or both the sidewall and the base to define an enclosed portion ( 27 ) of the base, and 
 deforming and stretching ( 35 ) at least a portion of the enclosed portion of the base, thereby increasing the surface area and reducing the thickness of the enclosed portion, wherein the annular clamping is adapted to restrict or prevent metal flow from the clamped region into the enclosed portion during the stretching operation. 
   
     
     
         2 . The method of  claim 1  wherein the annealing step is performed before the stretching operation, and the aluminum material on which the annealing step is performed is in the form of a pre-formed sheet. 
     
     
         3 . The method of  claim 1  wherein the annealing step is performed before the stretching operation, and the aluminum material on which the annealing step is performed is in a cup form. 
     
     
         4 . The method of  claim 1 ,  2 , or  3  further comprising performing a drawing operation ( 40 ) after the stretching operation; the drawings operation including drawing ( 43 ,  44 ,  45 ) the cup to pull and transfer material (B, C) outwardly from the stretched and thinned base. 
     
     
         5 . A method of  claim 4  wherein the clamping ( 36 ,  37 ) step of the stretching operation ( 30 ) comprises clamping the annular region ( 26 ) on the base ( 25 ), the enclosed portion ( 27 ) being that part of the base located radially inward of the clamped region. 
     
     
         6 . The method of  claim 1 ,  2 , or  3  wherein the clamping ( 36 ,  37 ) step of the stretching operation ( 30 ) comprises using one or more clamping elements having a clamping face with a textured surface. 
     
     
         7 . The method of  claim 1 ,  2 , or  3  wherein the stretching operation ( 30 ) comprises moving a stretch punch ( 35 ) relatively toward the cup ( 23 ) such that the stretch punch deforms and stretches at least a portion of the enclosed portion ( 27 ) of the base. 
     
     
         8 . A method of  claim 1 ,  2 , or  3  further comprising an initial drawing operation ( 10 ) performed before the stretching operation on the aluminum material, the initial drawing operation comprising drawing ( 11 ,  12 ,  13 ) the aluminum sheet to form the cup ( 23 ). 
     
     
         9 . The method of  claim 4  wherein the drawing operation further comprises or is followed by a step of ironing the sidewall. 
     
     
         10 . A method for manufacture of an aluminum cup, the method comprising the following operations:
 i. annealing an aluminum material;   ii. performing a stretching operation on the aluminum material that has the form of an aluminum sheet, the operation including:
 clamping an annular region on the sheet to define an enclosed portion, and 
 deforming and stretching at least a portion of the enclosed portion of the base, thereby increasing the surface area and reducing the thickness of the enclosed portion, wherein the annular clamping is adapted to restrict or prevent metal flow from the clamped region into the enclosed portion during the stretching operation. 
   iii. performing a drawing operation after the stretching operation, the drawing operation including drawing the aluminum sheet into a cup having a sidewall and an integral base.   
     
     
         11 . The method of  claim 10  wherein the annealing step is performed before the stretching operation, and the aluminum material on which the annealing step is performed is in the form of a pre-formed sheet. 
     
     
         12 . The method of  claim 10 , wherein the drawing operation is adapted such that material of the stretched and thinned enclosed portion is pulled and transferred into the sidewall. 
     
     
         13 . The method of  claim 10  wherein the stretching operation is performed on a plurality of enclosed portions separated from each other and disposed across the area of the metal sheet. 
     
     
         14 . The method of  claim 10  wherein the drawing operation comprises or is followed by the step of ironing the sidewall. 
     
     
         15 . The method of  claim 10  wherein the annular region has a round shape. 
     
     
         16 . The method of  claim 10  wherein the annular region has an angular shape. 
     
     
         17 . The method of  claim 10  wherein the base comprises material from the stretched and thinned enclosed portion and the drawing operation is adapted to pull and transfer outwardly material of the stretched and thinned enclosed portion. 
     
     
         18 . A method for manufacture of an aluminum cup, comprising the steps of:
 i. obtaining annealed or partially annealed aluminum;   ii. performing a stretching operation ( 30 ) on a cup ( 23 ) that is formed of the aluminum material and that has a sidewall ( 24 ) and an integral base ( 25 ), the stretching operation including:
 clamping ( 36 ,  37 ) an annular region ( 26 ) on either or both the sidewall and the base to define an enclosed portion ( 27 ) of the base, and 
 deforming and stretching ( 35 ) at least a portion of the enclosed portion of the base, thereby increasing the surface area and reducing the thickness of the enclosed portion, wherein the annular clamping is adapted to restrict or prevent metal flow from the clamped region into the enclosed portion during the stretching operation. 
   
     
     
         19 . The method of  claim 18  wherein the enclosed portion of the base is deformed and stretched at an elongation rate of greater than 5 percent. 
     
     
         20 . A cup formed of an aluminum material and having a sidewall and integral base, wherein the base is a stretched base such that the thickness of the base is less than the ingoing gauge of the metal sheet used to form the cup. 
     
     
         21 . The cup of  claim 20  wherein the stretched base achieves a thinning of greater than 8 percent.