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 center panel;
a countersink bead that extends in a 360 degree arc and has an inner wall and an outer wall joined by a generally curved bottom portion, wherein the outer wall has an outer wall height, and wherein at least a portion of the outer wall height has an expanded diameter that extends less than 360 degrees around the 360 degree arc;
a shoulder joining the inner wall of the countersink bead to the center panel;
a chuck wall portion extending up from the outer wall of the countersink; and
a seaming panel extending from the chuck wall portion.
2. The can end shell of claim 1 , further comprising two or more portions of the outer wall height having expanded diameters that each extend less than 360 degrees.