EP0512984B1

EP0512984B1 - Method and apparatus for processing containers

Info

Publication number: EP0512984B1
Application number: EP90907607A
Authority: EP
Inventors: Andrew Halasz; Sylvan Praturlon; Thomas E. Moloney; Nelson N. Chernikoff; Richard D. Zenger; Edward K. Cassidy; John M. Mann
Original assignee: American National Can Co
Current assignee: Rexam Beverage Can Co
Priority date: 1990-01-26
Filing date: 1990-01-26
Publication date: 1994-12-14
Anticipated expiration: 2010-01-26
Also published as: CA2074526A1; ES2066204T3; WO1991011275A1; AU655754B2; CA2074526C; JP3149945B2; DE69015210D1; EP0512984A1; AU5637190A; ATE115447T1; JPH05503878A; DE69015210T2

Abstract

A drawn and ironed container (C) that includes a cylindrical side wall, a smoothly-tapered neck (134) with an open end and an integral bottom wall (137) at the opposite end has a plurality of inwardly-deformed panel segments (130) located in the side wall between adjacent arcuate segments (132) with the panel defining generally chordal bottom walls for the panel segments. The container is formed using a multi-station processing apparatus that consists of a plurality of identical stations (30) located around the periphery of a rotating turret (26). Each station includes a support mandrel (50), a container loading means (52, 53) and an impression mandrel (54), with the impression mandrel being pivoted into and out of pressure engagement with the support mandrel to deform the side wall of the container. The support mandrel has a cylindrical peripheral surface (102) that conforms to the inner diameter of the container side wall and has circumferentially-spaced, axially-extending pockets (104). The pockets have sharp opposite edges (108a) that cooperate with the impression mandrel to produce the panel segments in the side wall.

Description

This invention relates generally to two-piece container constructions, and more particularly to a method and apparatus for processing such containers to increase the strength thereof, as well as improve the appearance.

Background Prior Art

Two-piece cans are the most common type of metal container used in the beer and beverage industry, as well as for aerosol and food packaging. The two-piece container consists of a unitary body, including a side wall open at one end with an integral end wall at the other end. The integral end wall is usually formed to a domed-shaped configuration to increase the overall strength of the container. An annular portion is usually formed to a special configuration between the center dome panel of the bottom wall and the side wall that defines a reduced diameter support for the container and also provides a nesting feature for nesting with the end of an adjacent container, which is seamed to the open end thereof.
An exemplary bottom profile for a drawn and ironed container that has achieved a remarkable degree of commercial success is disclosed in U.S. Patent No. 4,685,582. The container disclosed therein also includes an upper end portion that has a reduced neck so that a second end panel or end having a smaller diameter can be utilized to enclose the open-ended drawn and ironed container.
In most cases, containers that are used for beer and carbonated beverages are formed from a flat aluminum disc to an outside diameter of 2-11/16th inch (referred to as a "211-container") and the upper open end is reduced in diameter to form a 209-neck (2-9/16th inch) or any other smaller diameter, such as a 207½-neck, a 206-neck, and even a 204-neck or smaller so that smaller diameter ends can be utilized in the finished package.
An important competitive objective in the packaging industry is to reduce the total can weight as much as possible, while maintaining its strength and performance, in accordance with industry requirements. For pressurized contents, such as soft drinks or beer, the integral bottom end wall of the container usually has the same metal thickness gauge as the initial disc and the side wall is reduced through a drawing and ironing process to a thickness approaching one-third of the thickness of the original metal disc. Accordingly, to minimize overall weight, the can top or end panel that forms the second piece of the two-piece can is made as diametrically small as possible, while still maintaining the structural integrity of the container, the functionality thereof, and an aesthetically-pleasing appearance.
In the manufacture of containers of this type, a sheet of stock material of predetermined thickness is fed to a cupping press, wherein circular discs are cut from the stock material and are transformed into cups having a diameter which is considerably larger than the ultimate diameter of the finished container.
The preformed cups are then transferred to a container-forming apparatus, commonly referred to as a "bodymaker", wherein the cup is aligned with a punch carried on a reciprocable ram which cooperates with a plurality of spaced ironing dies and a doming mechanism located at the end of the path of the punch. During the forming process, the punch initially cooperates with a redraw assembly in which the shallow cup is redrawn to a smaller diameter that has an internal diameter approximately equal to the internal diameter of the ultimately-finished container and a height that is greater than the height of the original cup.
Each cup then passes through a series of ironing dies having progressively reduced diameters so that the side wall of the container is progressively reduced in thickness, while the height of the container increases. At the end of the stroke for the punch or ram, the end of the container is forced into a predetermined configuration to form an integral end wall that has a central inwardly-domed panel and a specially-configured peripheral annular bead or support portion. The drawn and ironed container is then trimmed to a selected height and coated and labeled, and a reduced tapered neck is produced on the open end.
To produce a container that can be price competitive and yet meet the rigid industry requirements, particularly for pressurized contents, such as beer and carbonated beverages, the Assignee of the present invention has developed a die necking operation for sequentially reducing the upper open end of the container to a smooth die neck configuration. This is done through a plurality of steps until the desired reduction for an end, such as a 206- or 204-end, is achieved. This process is disclosed in U.S. Patent No. 4,774,839, incorporated herein by reference. A container of the type having a bottom profile, such as disclosed in U.S. Patent No. 4,685,582, and a smooth die neck configuration illustrated in the above-referenced patent has increased strength characteristics and the overall aesthetic appearance has been enhanced.
In order to further enhance the overall appearance of the two-piece drawn and ironed container, it has also been proposed to deform the container side wall to produce a fluted appearance, such as disclosed in U.S. Patent Nos. DES 283,011 and DES 290,688.
According to the present invention there is provided a method of furthering production of a container, having a longitudinal axis and a side wall which is integral with a bottom having a center domed portion, and a countersink having an annular, substantially longitudinal inner wall and an outer annular wall comprising the step of reforming the bottom characterized by:
supporting said container in a jig, said jig having a bottom peripheral profile portion substantially corresponding in shape to said outer annular wall of said container;
mating the bottom peripheral profile portion of said jig with said outer annular wall; and
bringing a reforming roller into engagement with said inner wall, said reforming roller rotating along said inner wall and about an arcuate path in substantially radial alignment with said mating of said jig and said outer annular wall.
The invention includes apparatus, according to claim 5.
WO83/02577 (Claydon, et. al.) which forms the base of the preambles of claims 1 and 5 discloses various embodiments for reforming the bottom countersink of a container. According to Claydon, the container 10 is supported at its open end by a rotatable pad and at its closed end by various configurations of a support chuck. In each embodiment of Claydon, the support chuck is positioned within the bottom countersink of the container. A work roll is then moved radially inwardly to engage the outer annular wall of the container.
The container produced by the method of the present invention can be formed from a stock material, preferably an aluminum flat disc having a thickness of less than 0,0305 cm (0.0120 inch) and meet the minimum crush and buckle requirements of 1110 N (250 pounds) and 1,6 N/mm² (90 psi), respectively.
The container, which is formed from a flat metal disc, preferably aluminum, includes a bottom wall that has a thickness substantially equal to the thickness of the stock material and a reduced side wall thickness that is on the order of 1/3 the thickness of the stock material, with the bottom wall having a central inwardly-domed panel connected to the side wall through a countersink that has outer and inner, generally flat, substantially vertical walls.

Brief Description of the Drawings

Figure 1: is a fragmentary cross-sectional view showing the apparatus utilised for reforming the container bottom wall;
Figure 2: is an enlarged fragmentary cross-sectional view similar to Fig. 1.

Detailed Description

According to the invention, the container that has been formed in accordance with known teachings has even more significantly improved performance characteristics by reforming the bottom end wall of the container from the initial configuration, as disclosed in the above-mentioned '582 patent. Thus, as shown in Figs 1 and 2, after the fluted container has been necked and flanged and has been internally spray coated and externally printed the bottom profile, more specifically the countersink or chime area of the bottom wall, is reshaped by reforming the inner wall of the countersink to further improve buckle resistance and decrease can growth. This particular process would also allow further reduction in stock metal thickness without any change in the cut edge diameter of the initial disc.
Thus, as shown in Fig 1, the finished drawn and ironed container is supported in a suitable jig 150 that has an internal opening 152 which corresponds to the outer peripheral diameter of the container C. The jig has a lower profile portion 154 that conforms to the countersink wall portion of the bottom wall of the container, as orginally formed in accordance with the process disclosed in the '582 patent.
A plug 156 is inserted into the upper end of the opening and securely held in the top of the container. The bottom peripheral profile 154 of the jig 150 is in extended contact with the container bottom 137. A reforming roller 160 is brought into engagement with the outside of the domed end 162 of the container and is supported on a shaft 164 that is designed to be rotated along an arcuate path around the center axis for the container C. The roller has a peripheral configuration 166 which defines a substantially vertical upwardly and outwardly tapered wall having a generally arcuate upper portion 168 so that the inner wall 170 of the countersink is reformed to a more vertical profile while the dome 162 is stretched to a small degree. The outer wall 172 is held to its original configuration. Alternatively, the outer wall could also be reformed with the inner wall.
It has been found that this reforming operation significantly improves buckle resistance and decreases the amount of can growth, i.e., the amount that the bottom end wall is elongated when pressure is applied internally of the container.
Thus, in summary, the container produced according to the method and apparatus of the present invention has significantly less container growth during internal pressurization, and also has improved buckle resistance. The container constructed in accordance with the present invention has been found to be capable of being produced from stock flat disc material having a significantly reduced thickness.

Claims

A method of furthering production of a container, having a longitudinal axis and a side wall (129) which is integral with a bottom (137) having a center domed portion (162), and a countersink having an annular, substantially longitudinal inner wall (170) and an outer annular wall (172) comprising the step of reforming the bottom (137) characterised by:
supporting said container in a jig (150), said jig (150) having a bottom peripheral profile portion (154) substantially corresponding in shape to said outer annular wall (172) of said container;
mating the bottom peripheral profile portion (154) of said jig (150) with said outer annular wall (172); and
bringing a reforming roller (160) into engagement with said inner wall (170), said reforming roller (160) rotating along said inner wall (170) and about an arcuate path in substantially radial alignment with said mating of said jig (150) and said outer annular wall (172).
The method of claim 1, said reforming roller (160) being rotated about an arcuate path equidistant from said longitudinal axis.
The method of claim 1, wherein said inner wall (170) is reformed to a more vertical position.
The method of claim 1, wherein said roller (160) has a peripheral configuration (166) which defines a substantially vertical upwardly and outwardly tapered wall having a generally arcuate portion (168).
An apparatus for furthering production of a container having a longitudinal axis and a side wall (129) which is integral with a bottom (137) having a center domed portion (162), and a countersink having an annular, substantially longitudinal inner wall (170) and an outer annular wall (173) by reforming the bottom (137), said apparatus being characterized by :
a jig (150) having a bottom peripheral profile portion (154) substantially corresponding in shape to said outer annular wall (172) of said container;
means for supporting said container in said jig (150);
means for bringing a reforming roller (160) into engagement with said inner wall (170);
means for rotating said reforming roller (160) along said inner wall (170) and about an arcuate path in substantially radial alignment with said bottom profile (154) of said jig (15) and said outer annular wall (172).
The apparatus of claim 5, including means for rotating said reforming roller (160) about an arcuate path equidistant from the axis of the container.