Method of making a tear open closure

Claim 1

A method of making a substantially full opening tear-open sheet metal closure for a container, said closure comprising a centrally disposed removable panel, and an integral U-shape rim forming a peripherally extending channel around said removable panel, said rim comprising an inner chime wall and an outer chime wall, spaced apart to form said channel intermediate said chime walls, said closure having a circumferentially extending predetermined line-of-weakening disposed intermediate said inner chime wall and said removable panel, said line-of-weakening being defined by an outwardly canted score line depressed from the outside surface of said closure, said score line being configured to form a circumferentially extending smooth residual edge at its intersection with the outside surface of said inner chime wall whereby tearing along the line-of-weakening to remove said removable panel forms a raw edge which is nearer the wall of the container than said residual edge, the method comprising the steps of: forming said line-of-weakening in a generally planar blank of sheet metal by die stamping an endless score line in the outside surface of said blank to form a thin wall portion therein; then, forming the periperal portion of said blank disposed outward of said score line into said integral peripheral U-shape rim while supporting the removable panel portion of said blank so that the forming of the rim causes said score line to become outwardly canted from said residual edge, said cant being sufficient to position said score line defined line-ofweakening nearer the wall of the container to which said closure is secured than said residual edge.

Claim 2

A method of making a substantially full opening tear-open sheet metal closure for a container, said closure comprising a centrally disposed removable panel, and an integral U-shape rim forming a peripherally extending channel around said removable panel, said rim comprising an inner chime wall and an outer chime wall, spaced apart to form said channel intermediate said chime walls, said closure having a circumferentially extending predetermined line-of-weakening disposed intermediate said inner chime wall and said removable panel, said line-of-weakening being defined by an outwardly canted score line depressed from the outside surface of said closure, said score line being configured to form a circumferentially extending smooth residual edge at its intersection with the outside surface of said inner chime wall whereby tearing along the line-of-weakening to remove said removable panel forms a raw edge which is nearer the wall of the container than said residual edge, the method comprising the steps of: forming said line-of-weakening in a generally planar blank of sheet metal by die stamping an endless score line in the outside surface of said blank to form a thin wall portion therein; then, forming the periperal portion of said blank disposed outward of said score line into said integral peripheral U-shape rim while supporting the removable panel portion of said blank so that the forming of the rim causes said score line to become outwardly canted from said residual edge, said cant being sufficient to position said score line defined line-ofweakening nearer the wall of the container to which said closure is secured than said residual edge.

Claim 4

A method of making a substantially full opening tear-open sheet metal end closure for a right circular cylindrical tubular container, said end closure comprising a centrally disposed removable panel, a U-shape rim forming a peripherally extending channel around said removable panel, and a fillet intermediate said removable panel and said rim, said rim comprising a substantially right circular cylindrical inner chime wall and a substantially right circular cylindrical outer chime wall with said channel intermediate said chime walls, said closure having a circularly extending endless line-of-weakening disposed in said fillet, said line-of-weakening being defined by a radially outwardly canted score line configured to form a thin wall portion recessed from the adjacent outside surface of said rim and to form a circularly extending smooth residual edge at the intersection of said score line with the outside surface of the fillet contiguous to said inner chime wall, said cant and said recess being sufficient to position said predetermined line-of-weakening nearer the wall of said container than said residual edge whereby tearing along the line-of-weakening to remove said removable panel forms a raw edge nearer the wall of said container than said residual edge, the method comprising the steps of: forming said line-of-weakening in a circular planar blank of sheet metal by die stamping an endless score line in the outside surface of said blank; simultaneously folding the entire peripheral portion of said blank to form said fillet and said inner chime wall by telescoping the rim of a rimmed die member over said blank while supporting the removable panel of said blank on a male die member; limiting the movement of the edge of said blank while forming said fillet and said inner chime wall so that the outer chime forming portion of the blank becomes outwardly flared upon completion of forming said fillet and said inner chime wall; reverse folding the outer chime forming portion of said blank relative to said inner chime wall and sizing said outer chime forming portion into an annular space between a radially outwardly facing cylindrical wall of said rimmed die member and a radially inwardly facing cylindrical wall of a female die member by simultaneously telescoping said male and rimmed die members with said blank clamped therebetween into said female die member.

Claim 5

A method of making a substantially full opening tear-open sheet metal end closure for a right circular cylindrical tubular container, said end closure comprising a centrally disposed removable panel, a U-shape rim forming a peripherally extending channel around said removable panel, and a fillet intermediate said removable panel and said rim, said rim comprising a substantially right circular cylindrical inner chime wall and a substantially right circular cylindrical outer chime wall with said channel intermediate said chime walls, said closure having a circularly extending endless line-of-weakening disposed in said fillet, said line-of-weakening being defined by a radially outwardly canted score line configured to form a thin wall portion recessed from the adjacent outside surface of said rim and to form a circularly extending smooth residual edge at the intersection of said score line with the outside surface of the fillet contiguous to said inner chime wall, said cant and said recess being sufficient to position said predetermined line-of-weakening nearer the wall of said container than said residual edge whereby tearing along the line-of-weakening to remove said removable panel forms a raw edge nearer the wall of said container than said residual edge, the method comprising the steps of: forming said line-of-weakening in a circular planar blank of sheet metal by die stamping an endless score line in the outside surface of said blank; simultaneously folding the entire peripheral portion of said blank to form said fillet and said inner chime wall by telescoping the rim of a rimmed die member over said blank while supporting the removable panel of said blank on a male die member; limiting the movement of the edge of said blank while forming said fillet and said inner chime wall so that the outer chime forming portion of the blank becomes outwardly flared upon completion of forming said fillet and said inner chime wall; reverse folding the outer chime forming portion of said blank relative to said inner chime wall and sizing said outer chime forming portion into an annular space between a radially outwardly facing cylindrical wall of said rimmed die member and a radially inwardly facing cylindrical wall of a female die member by simultaneously telescoping said male and rimmed die members with said blank clamped therebetween into said female die member.