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(11) | EP 0 151 298 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Shell for can |
| (57) The disclosure relates to a novel shell such as used in the . manufacture of can
ends, and to a method and tools for making such a shell. A non-circular blank (B)
having rounded comers is cut from thin metal. The blank is oblong in a direction transverse
to the grain of the metal. A first set of tools separates the blanks and forms a substantially
flat central panel (10) and an upward-extending chuck wall (12) about the edge of
the panel to produce a partially formed shell. The junction area between said panel
and said chuck wall has a relatively large radius of curvature at this time. A second
set of tools forms in the blank a lip (53) extending outward from the upper end of
the chuck wall and generally parallel to said panel; then the panel and the clluck
wall are separately gripped, followed by relative movement between the panel and the
chuck wall while wrapping the junction area around a forming punch to form a panel
wall (11) in said junction area extending upward from the inner part of said chuck
watt. Then the lip is formed into a curl edge section (13) which ends in an inner
curl diameter that is round and concentric with the chuck wall, and has progressively
lesser radii of curvature from upper end of the chuck wall to the Inner curl diameter.
The resulting shell is characterised by a curl diameter being round and concentric
with the chuck wall and essentially uniformly spaced therefrom, and by having an essentially
constant thickness throughout the central panel, the panel wall and chuck wall and
the curved section therebetween. |