A can end having a countersink bead, an inclined chuck wall and a strong seam, resists distortion from its circular profile when subjected to thermal processing or when packaging carbonated beverages. This high hoop strength affects the manner in which the can end ultimately fails when placed under extreme abuse conditions, even if buckle pressure performance is within industry specified standards. The can end of the invention has control features introduced which control the failure mode whilst maintaining specified buckle pressure performance. In one embodiment, the can end has a two part wall and a control feature that comprises expansion of the countersink bead to act as a trigger for local peaking, together with a groove in the chuck wall which prevents the peaking force from being concentrated at a single point which could result in leaking by the production of a pin hole.
1. A can end shell comprising:
a circular center panel;
a countersink bead having an inner wall and an outer wall joined by a generally curved bottom portion;
a flattened strain limiting shoulder for triggering peaking joining the inner wall of the countersink bead to the center panel, the flattened shoulder extending around a 360 degree arc;
a multipart chuck wall portion extending up from the outer wall of the countersink, at least one part of the chuckwall being curved in cross section; and
a seaming panel extending from the chuck wall portion.
2. The can end shell of claim 1 , wherein the flattened shoulder is coined.
3. The can of claim 1 , wherein the can end shell further comprises an indentation positioned at least partially in the upper half of the chuck wall, the indentation extending either internally or externally, or a combination of these.
4. A can end shell for seaming onto a can body, the can end shell comprising:
a circular center panel;
a countersink bead having an inner wall and an outer wall joined by a generally curved bottom portion;
a flattened strain limiting shoulder for triggering peaking joining the inner wall of the countersink bead to the center panel, the flattened shoulder extending around a 360 degree arc;
a chuck wall portion located radially outwardly from the countersink, the chuck wall portion including a radially externally oriented indentation that is located at a point on the chuck wall that is proximate to a root of the seam upon seaming of the can end shell onto a can body; and
a seaming panel located radially outwardly from the chuck wall.
5. The can end shell of claim 4 , wherein the indentation is positioned at approximately a half way point of the chuckwall.
6. The can end shell of claim 4 , wherein the externally oriented indentation is located in the upper half of the chuck wall.
7. The can end shell of claim 4 , wherein the flattened shoulder is coined.
8. The can end shell of claim 4 , wherein the indentation extends around a 360 degree arc.
9. A can end shell for seaming onto a can body, the can end shell comprising:
a circular center panel,
a countersink bead having an inner wall and an outer wall joined by a generally curved bottom portion;
a flattened strain limiting shoulder for triggering peaking joining the inner wall of the countersink bead to the center panel, the flattened shoulder extending around a 360 degree arc;
a chuck wall portion located radially outwardly from the countersink, the chuck wall portion including a radially externally oriented indentation that is located at approximately a half way point of the chuckwall; and
a seaming panel located radially outwardly from the chuck wall.
10. The can end shell of claim 9 , wherein the flattened shoulder is coined.
11. The can end shell of claim 9 , wherein the indentation extends around a 360 degree arc.