Easy-Open Metal End for a Container, and Method for Making Same

Abstract

An easy-open metal end and a method for making same, in which a pre-score coining operation is performed, followed by an operation to form a score line. The coining step uses gentle-radius tooling designed not to crack or cut a protective coating on the metal end. Between the coining step and the score line-forming step, a paneling step is performed to pull out the loose metal generated in the coining step, such that end tension can be controlled more easily than in a conventional process. The coining operation thins the metal, so the score line can have less penetration than, and therefore can be narrower than, a conventional score line. Consequently, even if the score line does rust, it will be very small in width and thus relatively unnoticeable.

What is claimed is: 
     
         1 . A method for making an easy-open metal end, comprising the steps of:
 (a) providing a metal end comprising at least a metal layer, the metal end comprising a central panel, a countersink surrounding the central panel, and a chuck wall extending generally upwardly and outwardly from the countersink;   (b) engaging an upper coining tool with an upper surface of the central panel and a lower coining tool with a lower surface of the central panel, the upper and lower coining tools each defining a coining portion that is generally convex in a direction toward the respective surface of the central panel, and advancing the upper and lower coining tools so as to coin the upper surface to form an upper coined region that is generally concave in an upward direction and to coin the lower surface of the central panel to form a lower coined region that is generally concave in a downward direction, thereby thinning the metal layer between the coined regions and generating loose metal in the central panel as a result of metal flow away from the coined regions, the coined regions extending about a predetermined area of the central panel;   (c) forming a first metal-gathering panel in the central panel, thereby at least partially pulling out the loose metal generated in step (b); and   (d) forming a score line in at least one of the upper and lower coined regions, the score line extending about the predetermined area of the central panel so as to delineate a tear portion that is at least partially separable from a remainder of the central panel by severing the central panel along the score line.   
     
     
         2 . The method of  claim 1 , wherein step (c) is performed before step (d). 
     
     
         3 . The method of  claim 2 , further comprising the step of:
 (e) forming a second metal-gathering panel in the central panel.   
     
     
         4 . The method of  claim 3 , wherein step (e) is performed after step (d). 
     
     
         5 . The method of  claim 1 , wherein the coined regions formed in step (b) extend in a loop located proximate the countersink, and wherein step (c) comprises forming the first metal-gathering panel at a location spaced radially inwardly from the coined regions. 
     
     
         6 . The method of  claim 5 , wherein the first metal-gathering panel is formed in a generally C-shaped configuration extending parallel to the score line. 
     
     
         7 . The method of  claim 6 , wherein step (c) further comprises forming an additional metal-gathering panel spaced radially inwardly from the first metal-gathering panel. 
     
     
         8 . The method of  claim 1 , wherein an upper score line is formed in the upper coined region and a lower score line is formed in the lower coined region. 
     
     
         9 . The method of  claim 1 , wherein step (b) comprises forming the upper coined region and forming the lower coined region at different times. 
     
     
         10 . The method of  1 , wherein step (b) comprises forming the upper coined region and forming the lower coined region simultaneously. 
     
     
         11 . The method of  claim 1 , wherein step (a) comprises:
 providing a metal blank comprising a flat, disk-shaped member having at least a metal layer; and   deforming an outer peripheral portion of the blank to form the countersink and chuck wall.   
     
     
         12 . The method of  claim 1 , wherein the metal end comprises a polymeric coating on at least an upper surface of the metal layer, and wherein step (b) is carried out such that the forming of the upper and lower coined regions does not break the polymeric coating and expose bare metal. 
     
     
         13 . An easy-open metal end, comprising:
 a metal end comprising at least a metal layer, the metal end comprising a central panel, a countersink surrounding the central panel, and a chuck wall extending generally upwardly and outwardly from the countersink;   an upper coined region in an upper surface of the central panel, the upper coined region being generally concave in an upward direction, and a lower coined region in a lower surface of the central panel and directly opposite from the upper coined region, the lower coined region being generally concave in a downward direction, the metal layer being thinned between the coined regions, the coined regions extending about a predetermined area of the central panel;   a first metal-gathering panel in the central panel, loose metal generated by the formation of the coined regions being at least partially pulled out by the formation of the first metal-gathering panel; and   a score line formed in at least one of the upper and lower coined regions, the score line extending about the predetermined area of the central panel so as to delineate a tear portion that is at least partially separable from a remainder of the central panel by severing the central panel along the score line.   
     
     
         14 . The easy-open metal end of  claim 13 , further comprising a second metal-gathering panel in the central panel. 
     
     
         15 . The easy-open metal end of  claim 13 , wherein the coined regions extend in a closed loop located proximate the countersink, and wherein the first metal-gathering panel is at a location spaced radially inwardly from the coined regions. 
     
     
         16 . The easy-open metal end of  claim 13 , wherein the first metal-gathering panel is formed in a generally C-shaped configuration extending parallel to the score line. 
     
     
         17 . The easy-open metal end of  claim 16 , further comprising an additional metal-gathering panel spaced radially inwardly from the first metal-gathering panel. 
     
     
         18 . The easy-open metal end of  claim 13 , having an upper score line formed in the upper coined region and a lower score line formed in the lower coined region.