Method and apparatus for producing container body end countersink

A method for forming an end piece out of a portion of sheet metal comprising first and second surfaces, said end piece being attachable to an open end of a container body, said method comprising the steps of:

• feeding the portion of sheet metal to a first station;
• blanking the portion of sheet metal at said first station to obtain a blank;
• and
• forming said blank at said first station to produce said end piece, said end piece comprising a central panel, an annular groove disposed about a perimeter of said central panel and having a first curved portion disposed on a bottom of said annular groove and which is substantially defined by a radius of less than about 0.010 inches, and a flange disposed about said annular groove, wherein a portion of said first surface defined by a bottom portion of said annular groove is concave and a portion of said second surface defined by said bottom portion of said annular groove is convex, wherein said forming step comprises initiating a definition of said annular groove and completing said definition of said annular groove by moving said flange relative to said center panel and maintaining said portion of said first surface which will define said first curved portion of said annular groove substantially free from contact with any portion of said first station throughout said initiating a definition and completing said definition steps.

A method for reforming an end piece which is attachable to an open end of a container body, said end piece comprising a central panel having a first panel diameter, an annular groove disposed about a perimeter of said central panel and having a lower portion substantially defined by a first radius, and a flange disposed about said annular groove, wherein said annular groove further comprises a first curved portion extending between and integrally joining a chuckwall and an inner panel wall of said annular groove, said first curved portion being located at the bottom of said annular groove, said method comprising the step of:

• reworking said annular groove to reduce a magnitude of said first radius to a second radius, comprising the steps of exerting an inwardly-directed force on at least part of said annular groove and relative to said annular groove and collapsing said at least part of said annular groove inwardly relative to said annular groove, wherein at least one reworking tool comprising a punch and inner and outer die surfaces is used for said exerting step, wherein said exerting step comprises engaging portions of said chuckwall, said first curved portion and said inner panel wall between said punch and said inner and outer die surfaces, wherein said exerting step further comprises moving said punch relative to said annular groove and said inner and outer die surfaces to push unsupported concave portions of said first curved portion inwardly, toward said punch, and wherein said inner and outer die surfaces engage parts of said unsupported concave portions at an angle generally normal thereto.

A method for reforming an end piece which is attachable to an open end of a container body, said end piece comprising a central panel having a first panel diameter, an annular groove disposed about a perimeter of said central panel and having a lower portion substantially defined by a first radius, and a flange disposed about said annular groove, wherein said annular groove further comprises a first curved portion extending between and integrally joining a chuckwall and an inner panel wall of said annular groove, said first curved portion being located at the bottom of said annular groove, said method comprising the step of:

• reworking said annular groove to reduce a magnitude of said first radius to a second radius, comprising the steps of exerting an inwardly-directed force on at least part of said annular groove and relative to said annular groove and collapsing said at least part of said annular groove inwardly relative to said annular groove, wherein at least one reworking tool comprising a punch and inner and outer die surfaces is used for said exerting step, wherein said exerting step comprises engaging portions of said chuckwall, said first curved portion and said inner panel wall between said punch and said inner and outer die surfaces, wherein said exerting step further comprises moving said punch relative to said annular groove and said inner and outer die surfaces to push unsupported concave portions of said first curved portion inwardly, toward said punch, and wherein said exerting step further comprises exerting an inwardly-directed force toward said punch on an upper part of said annular groove by engaging an upper portion on said annular groove, and exerting an outwardly-directed force away from said punch on a lower part of said annular groove by engaging an intermediate portion of said annular groove, wherein said upper and intermediate portions are located on said inner panel wall.