Can bottom having improved strength and apparatus for making same

Abstract

A can bottom having an approximately frustoconical portion extending downwardly and inwardly from the can side wall, an annular nose portion extending downwardly from the approximately frustoconical portion, and a central portion extending upwardly and inwardly from the nose. The nose is formed by inner and outer circumferentially extending frustoconical walls that are joined by a downwardly convex arcuate portion. The inner surface of the arcuate portion of the nose has a radius of curvature adjacent the nose inner wall of at least 0.060 inch. The central portion of the can bottom has a substantially flat disc-shaped central section, having a diameter of at least about 1.40 inches, and an approximately dome-shaped and downwardly concave having a radius of curvature no greater than 1.475 inches. In a preferred embodiment of the invention, the inner surface of the arcuate portion of the nose is formed by a sector of a circle and has radius of curvature is no greater than about 0.070 inch. An apparatus for making the can bottom comprises a nose punch whose distal end has a radius of curvature that is equal to the radius of curvature of the can bottom nose and a die whose radius of curvature equals that of the dome.

Dependencies are inferred from the claim text.