US 11,883,872 B2
Metal containers and methods of manufacture
Paul Robert Dunwoody, Oxfordshire (GB)
Assigned to Crown Packaging Technology, Inc., Alsip, IL (US)
Filed by Crown Packaging Technology, Inc., Alsip, IL (US)
Filed on Jun. 7, 2021, as Appl. No. 17/340,647.
Application 17/340,647 is a continuation of application No. 16/072,083, granted, now 11,059,086, previously published as PCT/GB2017/050029, filed on Jan. 9, 2017.
Claims priority of application No. 1602042 (GB), filed on Feb. 4, 2016.
Prior Publication US 2021/0291249 A1, Sep. 23, 2021
Int. Cl. B21D 22/28 (2006.01); B21D 22/30 (2006.01); B21D 51/26 (2006.01); B21D 51/34 (2006.01)
CPC B21D 22/283 (2013.01) [B21D 22/28 (2013.01); B21D 22/30 (2013.01); B21D 51/26 (2013.01); B21D 51/34 (2013.01); B21D 51/2692 (2013.01)] 8 Claims
OG exemplary drawing
 
1. A method of reducing a thickness and increasing a height of a cylindrical wall of a metal cup so as to form a can body, the method comprising:
positioning a wall-ironing punch inside the cup, the punch including:
a first punch portion having a first diameter,
a second punch portion having a second diameter,
a third punch portion having a third diameter;
a first transition between the first punch portion and the second punch portion such that the second punch portion diameter is greater than the first punch portion diameter;
wherein the first punch portion corresponds to a closed end of the cup; and
a second transition between the second punch portion and the third punch portion such that the third punch portion diameter is greater than the second punch portion diameter;
moving an annular wall-ironing die axially over the closed end of the cup towards an open end of the cup, such that the wall-ironing die does not move beyond the open end of the cup, in order to iron the cylindrical wall from the closed end up to a position axially spaced from the open end, thereby forming the can body;
moving the wall-ironing die back in an opposite direction to remove the can body from the die; and
forming a curl at an uppermost end of the can body;
thereby forming a body-wall of the can body having a wall thickness proximate a base of the can body that is greater than a wall thickness of a second body-wall portion.