Apparatus and methods for simultaneously necking and flanging a can body member

The method of simultaneous necking and flanging of an unformed end portion including a rim portion of the side wall portion of a sheet metal can body member to form a curved necked-in portion connected to the side wall portion and a radially and axially outwardly extending flange portion between said necked-in portion and said rim portion, and comprising:

• positioning an outer forming member having a curved annular outer forming surface outside the can body member in juxtaposition to the outer peripheral surface of the unformed end portion, and positioning a first annular inner forming surface inside the can body member in juxtaposition to the inner peripheral surface of the unformed end portion radially inwardly opposite a first axially inwardly extending portion of the outer forming surface, and positioning a second annular inner forming surface inside the can body member in juxtaposition to the inner peripheral surface of the unformed end portion radially inwardly opposite a second axially outwardly extending portion of the outer forming surface;
• supportively engaging the entire circumference of a first portion of the inner peripheral surface of the can body member extending between the rim portion and said second annular inner forming surface, and supportively engaging an axially elongated segment of the circumference of a second portion of the inner surface of the can body member extending axially inwardly beyond said first annular inner forming surface a substantial distance beyond the unformed end portion;
• causing progressive radial inward relative displacement of the outer forming surface relative to the side wall portion of the can body member against the outer peripheral surface of the unformed end portion and forcing axially spaced interior peripheral surface portions of the unformed end portion into generally conforming engagement with said first annular inner forming surface and said second annular inner forming surface;
• progressively axially oppositely displacing said first annular inner forming surface and said second annular inner forming surface as said outer forming surface is progressively radially inwardly displaced relative to the side wall portion of said can body member;
• and
• continuously supporting at least an axially limited length of the entire circumference of the first portion of the inner peripheral surface of the can body member throughout the forming operation while maintaining the rim portion at or radially outwardly of the outer peripheral surface of the side wall portion of the can body member and without subjecting the formed flange portion to any compressive stresses.

The method of simultaneously necking and flanging an unformed end portion of a cylindrical side wall portion of a metallic can body member to provide an annular rim portion located on the open end of the can body member and having an outside diameter equal to or less than the outside diameter of the side wall portion, an axially and radially inwardly extending annular first flange portion located axially inwardly next adjacent the rim portion, an annular curved groove portion located axially inwardly next adjacent the first flange portion and having an outside diameter less than the rim portion, and an axially inwardly radially outwardly extending second flange portion located axially inwardly next adjacent the curved groove portion and connecting the curved groove portion to the side wall portion, and comprising the steps of:

• initially supporting the entire inside surface of the unformed end portion along an annular support area having a width extending axially between the axially outermost rim portion of the can body member and the plane of the center of curvature of the curved groove portion to be formed therein;
• initially supporting an axially extending circumferentially limited portion of the inside surface of the unformed end portion extending between the plane of the center of curvature of the curved groove portion to be formed therein and to the plane of and substantially axially inwardly beyond the plane of the intersection of the side wall portion and the second flange portion;
• simultaneously applying radially inwardly and axially inwardly directed forming forces to only one surface portion of limited circumferential length and radial width on the outer periphery of the unformed end portion along the plane of the center of curvature of the annular curved groove portion to be formed;
• and
• circumferentially changing the location of application of the forming forces and gradually increasing the magnitude of the forming forces while axially widening the distance between the annular support area and the axially extending circumferentially limited portion of the inside surface of the unformed end portion.

The method of simultaneously necking and flanging of an unformed end portion, next adjacent the rim portion of the side wall portion of a sheet metal can body member to form a curved necked-in portion in the unformed end portion next adjacent and connected to the side wall portion and to form a radially and axially outwardly extending formed flange portion between the formed curved necked-in portion and the rim portion, and comprising:

• locating a curved annular outer forming surface circumjacent and in radially outwardly spaced relationship to the unformed end portion;
• movably holding and supporting interior surfaces of and in and adjacent to the unformed end portion of the side wall portion of the can body member;
• providing an annular forming gap radially inwardly of the unformed end portion radially opposite the center of curvature of the forming surface;
• causing progressive radial inward movement of the forming surface relative to the can body member against the outer peripheral surface of the unformed end portion;
• holding the interior surface of the unformed end portion at axially spaced areas of abutment on axially opposite sides of the center of curvature of the forming surface;
• gradually increasing the radial inward location of the forming surface relative to the can body member while simultaneously progressively increasing the axial distance between the axially spaced areas of abutment on the interior surfaces of the unformed end portion;
• and
• maintaining the radial location of the rim portion at or radially outwardly of the outer peripheral surface of the side wall portion of the can body member throughout the forming operation without subjecting the flange portion of any compressive stresses.