Shaped metal container and method for making same
A shaped metal container having less metal than prior art shaped metal containers while still able to handle sufficient axial load and undergo shaping processes, including necking, without wrinkling, buckling, collapsing or other physical defect is disclosed. Processes for shaping a metal container having a sidewall of variable thickness, wherein a portion of the sidewall having a variable thickness is shaped using a die or dies are also disclosed.
1. A process for forming a metal container comprising:
providing a container having a sidewall, wherein the sidewall has a thickness, a thinnest portion, and a height, and wherein the thickness varies along the height of the sidewall by at least 0.001 inches; and
necking the container with a necking die so that a working surface of the necking die contacts a section of the sidewall and reduces a diameter of the section of the sidewall by at least 2% in a single stroke, wherein the thickness of the section of the sidewall being necked varies along the height of the sidewall by at least 0.001 inches at locations which directly contact the necking die before and after necking, wherein the section of the sidewall being necked includes the thinnest portion of the sidewall.
2. The process of claim 1 wherein the necking die comprises:
a necking surface and a relief;
wherein the necking surface comprises a land portion, a neck radius portion, and a shoulder radius portion, each having an inner diameter;
wherein the land portion is between the neck radius portion and the relief and the inner diameter of the land is a minimum diameter of the die;
wherein the inner diameters of the neck radius portion and the shoulder radius portion are greater than the inner diameter of the land;
wherein the relief comprises:
(a) a relief surface;
(b) an inner diameter of the relief surface is at least about 0.01 inches greater than the inner diameter of the land portion;
(c) an inner diameter of the relief surface is no greater than a maximum diameter so as to reduce but not eliminate frictional contact between the metal container and the relief surface while maintaining necking performance when necking the metal container; and
wherein the necking die is dimensioned so that when necking the metal container, the entire land and the relief travel relative to the container in an axial direction and at least a portion of the relief travels beyond a top of the container.
3. The process of claim 1 further comprising expanding the diameter of a portion of the sidewall.
4. The process of claim 3 wherein an expansion die expands the portion of the sidewall, wherein the expansion die comprises:
a work surface comprising a progressively expanding portion and a land portion; and
an undercut portion;
wherein the land portion is between the progressively expanding portion and the undercut portion and an outer diameter of the land portion is a maximum diameter of the die;
wherein the undercut portion comprises:
(a) an undercut surface; and
(b) an outer diameter of the undercut surface, wherein the outer diameter of the undercut surface is:
(i) at least approximately 0.01 inches smaller than the outer diameter of the land portion; and
(ii) no less than a minimum diameter so as to reduce but not eliminate frictional contact between the undercut surface and the metal container; and
wherein the work surface is dimensioned so that when inserted into the metal container the entire land portion and at least a portion of the undercut portion enter the metal container causing the diameter of the at least a portion of the sidewall to expand.
5. The process of claim 1 further comprising necking the container with a series of necking dies.
6. The process of claim 1 further comprising expanding the diameter of the portion of the sidewall with a series of expansion dies.
7. The process of claim 1 wherein the thickness of the section of the sidewall being necked varies along the height of the sidewall by at least 0.0015 inches.
8. The process of claim 1 wherein the thickness of the section of the sidewall being necked varies along the height of the sidewall by at least 0.002 inches.
9. A process for forming a metal container comprising:
providing a container having a sidewall, wherein the sidewall has a variable thickness between 0.005 inches and 0.0085 inches, a thinnest portion, and a height, and wherein the thickness varies along the height of the sidewall by at least 0.001 inches to not greater than 0.004 inches; and
necking the container with a necking die so that a working surface of the necking die contacts a section of the sidewall and reduces a diameter of the section of the sidewall by at least 2% in a single stroke, wherein the thickness of the section of the sidewall being necked varies along the height of the sidewall by at least 0.001 inches to not greater than 0.004 inches at locations which directly contact the necking die before and after necking, wherein the section of the sidewall being necked includes the thinnest portion of the sidewall.