Receptacles – End wall structure – One-piece side and end wall
Reexamination Certificate
2000-06-09
2001-09-25
Pollard, Steven (Department: 3727)
Receptacles
End wall structure
One-piece side and end wall
C220S604000, C220S906000
Reexamination Certificate
active
06293421
ABSTRACT:
BACKGROUND OF THE INVENTION
This patent application is a Continuation-in-Part of U.S. patent application No. 07/606,618, filed Apr. 6, 1990.
FIELD OF THE INVENTION
The present invention relates generally to metal container bodies of the type having a seamless sidewall and a bottom formed integrally therewith. More particularly, the present invention relates to a bottom contour that provides increased dome reversal pressure, that provides greater resistance to damage when dropped, and that minimizes or prevents growth in the height of a container in which the beverage is subjected to pasteurizing temperatures and/or extreme temperatures encountered in shipping and storage.
DESCRIPTION OF THE RELATED ART
There have been numerous container configurations of two-piece containers, the is, containers having a body that has an integral bottom wall at one end, and an opposite end that is configured to have a closure secured thereto. Container manufactures package beverages of various types in these containers formed of either steel or aluminum alloys.
In the production of these containers, it is important that the body wall and bottom wall of the container be as thin as possible so that the container can be sold at a competitive price. Much work has been done on thinking the body wall.
Aside from seeking thin body wall structures, various bottom wall configurations have been investigated. As early attempt in seeking sufficient strength of the bottom wall was in form the same into a spherical dome configuration. This general configuration is shown in Dunn et al., U.S. Pat. No. 3,760,751, issued Sep. 25, 1979. The bottom wall is thereby provided with an inwardly concave dome or bottom recess portion which includes a large portion of the area of the bottom wall of the container. This domed configuration provides increased strength and resists deformation of the bottom wall under increased internal pressure of the container with little change in the overall geometry of the bottom wall throughout the pressure range for which the container is designed.
The prior art that teaches domed bottoms also includes P. G. Stephan, U.S. Pat. No. 3,349,956, issued Oct. 31, 1967; Knousel et al., U.S. Pat. No. 3,693,828, issued Sep. 26, 1972; Dunn et al., U.S. Pat. No. 3,730,383, issued May 1, 1973; Toukmanian, U.S. Pat. No. 3,904,069, issued Sep. 9, 1976; Lyu et a., U.S. Pat. No. 3,942,673, issued Mar. 9, 1976; Miller et al., U.S. Pat. No. 4,294,373, issued Oct. 13, 1981; McMillin, U.S. Pat. No. 4,804,266, issued May 30, 1989; Pulciani et al., U.S. Pat. No. 4,685,582, issued Aug. 11, 1987, and Pulciani, et al., U.S. Pat. No. 4,768,672, issued Sep. 8, 1988, and Kawamoto et al., issued Apr. 24, 1990.
Patents which teach apparatus for forming containers with inwardly domed bottoms and/or which teach containers having inwardly domed bottoms, include Maeder et al., U.S. Pat. No. 4,289,014, issued Sep. 16, 1981; Gombas, U.S. Pat. No. 4,341,321, issued Jul. 27, 1982; Elert et al., U.S. Pat. No. 4,372,143, issued Feb. 8, 1983; and Pulciani et al., U.S. Pat. No. 4,620,434, issued Nov. 4, 1980.
Of the above-mentioned patents, Lyu et al., and Kawamoto et al., teach inwardly domed bottoms in which the shape of the inwardly domed bottom is ellipsoidal.
Stephan in U.S. Pat. No. 3,349,956, teaches using a reduced diameter annular supporting portion with an inwardly domed bottom disposed intermediate of the reduced diameter annular supporting pressure. Stephan also teaches stacking of the reduced diameter annular supporting portion inside the double-seamed top of another container.
Kneusei et al., in U.S. Pat. No. 3,693,828, teach a steel container having a bottom portion which is frustoconically shaped to provide a reduced diameter annular supporting portion, and having an internally domed bottom that is disposed radially inwardly of the annular supporting portion. Various contours of the bottom are adjusted to provide more uniform coating of the interior bottom surface, including a reduced radius of the domed bottom.
Pulciani et al., in U.S. Pat. Nos. 4,685,582 and 4,768,672, instead of the frustoconical portion of Kneusel et al., teach a transition portion between the cylindrically shaped body of the container and the reduced diameter annular supporting portion that includes a first annular arcuate portion that is convex with respect to the outside diameter of the container and a second annular arcuate portion that is convex with respect to the outside diameter of the container.
McMillin, in U.S. Pat. No. 4,834,256, teaches a transitional portion between the cylindrically shaped body of the container and the reduced diameter annular supporting portion that is contoured to provide stable stacking for container having a double-sensed top which is generally the same diameter as the cylindrical body, as well as providing stable stacking for containers having a double-seamed top that is smaller that the cylindrical body. In this design, containers with reduced diameter tops stack inside the reduced diameter annular supporting portion; and containers with larger tops stack against this specially contoured transitional portion.
Supik, in U.S. Pat. No. 4,732,292, issued Mar. 22, 1988, teaches making indentions in the bottom of a container that extend upwardly from the bottom. Various configurations of these indentations are shown. The indentations are said to increase the flexibility of the bottom and thereby prevent cracking of interior coatings when the containers are subjected to internal fluid pressures.
In U.S. Pat. No. 4,885,924, issued Dec. 12, 1989, which was disclosed in W.I.P.O. International Publication No. WO 83/02577 of Aug. 4, 1983, Claydon et al. teach apparatus for rolling the outer surface of the annular supporting portion radially inward, thereby reducing the radii of the annular supporting portion. This rolling of the annular supporting portion inwardly to prevent inversion of the dome when the container is subjected to internal fluid pressures.
Various of the prior art patents, including Pulciani et al., U.S. Pat. No. 4,620,434, teach contours which are designed to increase the pressure at which fluid inside the container reverses the dome at the bottom of the container. This pressure is called the static dome reversal pressure. In this patent, the contour of the transitional portion is given such great emphasis that the radius of the domed panel, through generally specified within a range, is not specified for the preferred embodiment.
However, it has been known that maximum values of static dome reversal pressure are achieved by increasing the curvature of the dome to an optimum value, and that further increases in the dome curvature result in decreases in static come reversal pressures.
As mentioned earlier, one of the problems is obtaining a maximum dome reversal pressure for a given metal thickness. However, another problem is obtaining resistance to damage when a filled container is dropped onto a hard surface.
Present industry testing for drop resistance is called the cumulative drop height. In this test, a filled container is dropped onto a steel plate from heights beginning at three inches and increasing by three inches for each successive drop. The drop height resistance is then the sum of all the distances at which the container is dropped, including the height at which the dome is reversed, or partially reversed. That is, the drop height resistance is the cumulative height at which the bottom contour is damaged sufficiently is preclude standing firmly upright on a flat surface.
In the U.S. patent application No. 07/606,618 of which this present application is a Continuation-in-Part, it was shown that decreasing the dome radius of the container increases the cumulative drop height resistance and decreases the dome reversal pressure. Further, it was shown in this prior application that increasing the height of the inner wall increases the dome reversal pressure.
However, as the dome radius is decreased for a given dome height, the inner wall decreases in height. Therefore, for a given dome hei
Baldwin Gary A.
Jentzsch K. Reed
Willoughby Otis H.
Ball Corporation
Pollard Steven
Sheridan & Ross P.C.
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