Three-Piece Can and Method of Making Same

Abstract

A method of making a can assembly includes double-seaming a double-countersink metal end onto a can body and reforming the double-countersink metal end so as to effectively yield a single-countersink metal end of smaller diameter. In the process, the region of the can body adjacent the metal end becomes necked-in. The method can be applied to make a stackable three-piece can in which the reformed smaller-diameter metal end will fit within a double-seam of a metal end attached to the opposite end of the can body.

What is claimed is: 
     
         1 . A stackable three-piece can comprising:
 a can body having a top opening and a bottom opening;   a first end having a curl and a countersink region, and a second end having a curl and a countersink region, at least the first end being a metal end;   a first double-seam formed between the first end and one end of the can body such that the first end closes the opening at said end, and a second double-seam formed between the second end and the other end of the can body such that the second end closes the opening at said end, each of the double-seams having an inside diameter and an outside diameter;   wherein the countersink region of the first end comprises a single-countersink and the countersink region of the second end comprises a double-countersink, the single-countersink comprising a single chuck wall adjacent the curl and extending axially and radially inwardly from the curl and terminating in a countersink radius, the double-countersink comprising an outer chuck wall adjacent the curl and extending axially and radially inwardly from the curl, a transition portion joined to the outer chuck wall and extending generally radially inwardly therefrom, and an inner chuck wall joined to the transition portion and extending axially and radially inwardly therefrom and terminating in a countersink radius, the outside diameter of the first double-seam being sized to fit within the inside diameter of the second double-seam.   
     
     
         2 . The stackable three-piece can of  claim 1 , wherein the single chuck wall is substantially straight from the curl to the countersink radius. 
     
     
         3 . The stackable three-piece can of  claim 1 , wherein the transition portion of the second end extends both radially inwardly and axially toward the first end. 
     
     
         4 . The stackable three-piece can of  claim 1 , wherein the can body comprises a composite can body having at least one paperboard ply and an impervious liner. 
     
     
         5 . The stackable three-piece can of  claim 4 , wherein the liner has a heat-sealable material forming a radially innermost surface of the can body. 
     
     
         6 . The stackable three-piece can of  claim 5 , wherein the ends are thermally fused to the can body via the heat-sealable material of the liner. 
     
     
         7 . The stackable three-piece can of  claim 1 , wherein the can body is constructed substantially of thermoplastic. 
     
     
         8 . The stackable three-piece can of  claim 1 , wherein the can body includes a metal layer. 
     
     
         9 . A method for making a stackable three-piece can, comprising the steps of:
 providing a can body having a top opening and a bottom opening;   providing a first end and a second end each having a curl and a countersink region, wherein at least the first end is a metal end;   wherein the countersink region of the first end comprises a double-countersink, the double-countersink comprising an outer chuck wall adjacent the curl and extending axially and radially inwardly from the curl, a transition portion joined to the outer chuck wall and extending generally radially inwardly therefrom, and an inner chuck wall joined to the transition portion and extending axially and radially inwardly therefrom and terminating in a countersink radius;   forming a first double-seam between the first end and one end of the can body such that the first end closes the opening at said end, and forming a second double-seam between the second end and the other end of the can body such that the second end closes the opening at said end, each of the double-seams having an inside diameter and an outside diameter; and   deforming the first double-seam and the outer chuck wall and transition portion of the first end radially inwardly so as to generally straighten out the countersink region of the first end and such that the outside diameter of the first double-seam is sized to fit within the inside diameter of the second double-seam.   
     
     
         10 . The method of  claim 9 , wherein the step of forming the first double-seam comprises the steps of
 using a first seaming chuck engaged with the outer chuck wall of the first end and a first seaming roll engaged with the curl so as to partially form the first double-seam; and   using the first seaming chuck with a second seaming roll to complete the formation of the first double-seam.   
     
     
         11 . The method of  claim 10 , wherein the step of deforming the first double-seam comprises using a third seaming member together with a second seaming chuck differing from the first seaming chuck, wherein the second seaming chuck engages the inner chuck wall and the third seaming member engages the first double-seam and urges the first double-seam radially inwardly. 
     
     
         12 . The method of  claim 9 , further comprising using a seaming compound to seal the metal end to the can body. 
     
     
         13 . The method of  claim 9 , further comprising the step of thermally fusing the ends to the can body by at least one heat-activated material disposed between opposing surfaces of the can body and each end. 
     
     
         14 . The method of  claim 13 , wherein the can body is constructed substantially of thermoplastic, and the thermal fusing step comprises heating and melting the thermoplastic in contact with the ends so as to thermally fuse the ends to the can body. 
     
     
         15 . The method of  claim 14 , wherein the ends include an interior-facing layer of heat-sealable material, and the thermal fusing step additionally comprises heating and melting the layer of heat-sealable material on each end in contact with the can body, such that the heat-sealable material layers and the thermoplastic of the can body are thermally fused together. 
     
     
         16 . A method for making a can assembly, comprising the steps of:
 providing a can body having a top opening and a bottom opening;   providing a metal end having a curl and a double-countersink, the double-countersink comprising an outer chuck wall adjacent the curl and extending axially and radially inwardly from the curl, a transition portion joined to the outer chuck wall and extending generally radially inwardly therefrom, and an inner chuck wall joined to the transition portion and extending axially and radially inwardly therefrom and terminating in a countersink radius;   forming a double-seam between the metal end and one end of the can body such that the metal end closes the opening at said end; and   deforming the double-seam and the outer chuck wall and transition portion radially inwardly so as to generally straighten out the countersink region of the metal end and such that the outside diameter of the double-seam is reduced.   
     
     
         17 . The method of  claim 16 , wherein the step of deforming the double-seam comprises using a seaming roll together with a seaming chuck, wherein the seaming chuck engages the inner chuck wall and is spaced from the outer chuck wall, and the seaming roll engages the double-seam and urges the double-seam and outer chuck wall radially inwardly. 
     
     
         18 . The method of  claim 16 , further comprising using a seaming compound to seal the metal end to the can body. 
     
     
         19 . The method of  claim 16 , further comprising the step of thermally fusing the metal end to the can body by at least one heat-activated material disposed between opposing surfaces of the can body and the metal end. 
     
     
         20 . The method of  claim 19 , wherein the can body is constructed substantially of thermoplastic, and the thermal fusing step comprises heating and melting the thermoplastic in contact with the metal end so as to thermally fuse the metal end to the can body. 
     
     
         21 . The method of  claim 20 , wherein the metal end includes an interior-facing layer of heat-sealable material, and the thermal fusing step additionally comprises heating and melting the layer of heat-sealable material on the metal end in contact with the can body, such that the heat-sealable material layer and the thermoplastic of the can body are thermally fused together. 
     
     
         22 . The method of  claim 19 , wherein at least an inner surface of the can body includes a heat-sealable material, and the thermal fusing step comprises heating and melting the heat-sealable material in contact with the metal end so as to thermally fuse the metal end to the can body. 
     
     
         23 . The method of  claim 22 , wherein the can body includes a metal layer in addition to the heat-sealable material. 
     
     
         24 . The method of  claim 19 , wherein the metal end has a heat-sealable surface on an interior-facing surface of the metal end. 
     
     
         25 . The method of  claim 24 , wherein the heat-sealable surface is bare metal and the heat-activated material is thermally fused to the bare metal. 
     
     
         26 . The method of  claim 24 , wherein the metal end comprises thermoplastic-coated metal, the thermoplastic coating providing the heat-sealable surface. 
     
     
         27 . The method of  claim 24 , wherein the metal end comprises metal with a heat-sealable coating, the heat-sealable coating providing the heat-sealable surface. 
     
     
         28 . A method of making a can assembly, comprising double-seaming a double-countersink metal end onto a can body and reforming the double-countersink metal end so as to effectively yield a single-countersink metal end of smaller diameter.