Method of Manufacturing a Necked Container

Abstract

A method for manufacturing a necked container starting with a metal body part of which the overlapping edges are welded together, after which at least part of the metal body is ironed to minimize or remove the difference in thickness between the welded part and the other part of the wall of the metal body part. After the ironing operation the metal body part is necked and provided with a top part. A bottom part is connected to the metal body part which can be done depending on the extent of the ironing process before or after ironing the metal body part and before or after necking the metal body part. Furthermore, the method provides a single seam method for bottom part and metal body part, resulting in an inwardly directed seam.

1 . A method of manufacturing a necked container comprising at least the steps of: 
 forming a metal body part of circular cross-section from a metal sheet, with two edges of the sheet overlapping,    connecting the overlapping edges of the metal body part to each other by means of welding,    ironing the wall of the metal body part over at least part of the length of the metal body part in order to reduce the thickness of the welded overlapping edges,    die necking the ironed part of the metal body part in a number of successive steps, and    providing the metal body part with at least a bottom part.    
   
   
       2 . The method according to  claim 1 , wherein the wall of the metal body part is ironed over at least the length needed for die necking one side of the metal body part to the chosen final shape.  
   
   
       3 . The method according to  claim 1 , wherein the method further comprises the steps of: 
 flanging or curling the edge of the metal body part at the necked outer end of the metal body part, the flange or curl being directed outward,    connecting a top part to said flanged or curled edge of the metal body part.    
   
   
       4 . The method according to  claim 3 , wherein the top part that is connected to the curled edge of the metal body part is a valve cap.  
   
   
       5 . The method according to  claim 1 , wherein the thickness of the overlapping edges of the body part after welding is in the range of 1.1-1.5 times the thickness of the original material of the metal body part.  
   
   
       6 . The method according to  claim 1 , wherein the bottom part is seamed to the metal body part at the outer end of the metal body part opposite of the necked part of the metal body part.  
   
   
       7 . The method according to  claim 6 , wherein the bottom part is connected to the metal body part by means of a double seam.  
   
   
       8 . The method according to  claim 6 , wherein the method comprises the steps of: 
 providing a metal bottom part with a flanged edge, the outside of the flanged edge corresponding to the inner side of the body part at the location where the bottom part is to be connected to the body part,    placing the bottom part within the body part at said location, and    folding the outer end of the body part that extends beyond the flanged edge of the bottom part inward against the inside of the flanged edge of the bottom part.    
   
   
       9 . The method according to  claim 8 , wherein the outer end of the body part that extends beyond the flanged edge of the bottom part is folded such that the largest part of the inner side of said outer end of the body part butts against the inner surface of the flanged edge of the bottom part.  
   
   
       10 . The method according to  claim 8 , wherein the outer end of the body part that extends beyond the flanged edge of the bottom part is folded inward such that the edge between outer and inner side of said outer end of the body part butts against the inner side of the flanged edge of the bottom part.  
   
   
       11 . The method according to  claim 8 , wherein at least the outer side of the flanged edge of the bottom part is provided with sealing means.  
   
   
       12 . The method according to  claim 8 , wherein the bottom part is made out of a sheet provided at least at one side with a coating, the coating consisting of or comprising sealing means or provided with a coating that is suitable to be used as sealing means.  
   
   
       13 . The method according to  claim 1 , wherein at least the metal body part is made of tin plated steel.  
   
   
       14 . The method according to  claim 1 , wherein the metal body part is die necked and the die necked outer end is curled outward such that a standard sized valve cup can be connected to the curled outer end.  
   
   
       15 . The method according to  claim 1 , wherein the thickness of the overlapping edges of the body part after welding is in the range of 1.1-1.3 times the thickness of the original material of the metal body part.