CA1152012A

CA1152012A - Convex bottom - two-piece container

Info

Publication number: CA1152012A
Application number: CA000376113A
Authority: CA
Inventors: Robert J. Gruodis; William T. Franz; Edward J. Hayes
Original assignee: Continental Group Inc
Current assignee: Continental Group Inc
Priority date: 1980-05-13
Filing date: 1981-04-23
Publication date: 1983-08-16
Also published as: GR74897B; JPS578648A; GB2075461A; KR830006083A; DE3117347A1; EP0040014A1; AU539873B2; MX152873A; AU6934481A; BR8102944A

Abstract

Abstract of the Disclosure A container made of thin sheet metal such as aluminum comprising a cylindrical side wall substantially thinner than the bottom and the bottom being generally a spherical section with nonsymmetrical projections thereon prompting seating areas offset toward the periphery of the bottom wall to provide a stable support for the container and transition areas between the projections and the can bottom which blend into each other in broad curved surfaces such as will not hinder spray applications of coatings onto the can bottom.

Description

Two-piece containers are well known. They comprise a body with an integral bottom at one end and a top end seamed to the other end of the body. One of the problems encountered by the industry in forming a thin-walled metal can structure resided in forming a suitable bottom which would seat the can in a stable position upon the conveyors. When empty, the cans are carried to the filler and then when the cans are filled, they are carried away to the packing sta-tions. The way such cans were made was to form a callotte in the can boktom so as to hold the pressure in the can without deforming and to provide an annular seating rim about the edge of the can body to stabilize the can as it was being transported. An example of such can is shown in U. S.
Patent 3,029,507. Other cans provide flexible bottoms which are concaved toward the interior of the can when unpressurized and expand into convex shape when pressurized. An example of such can is shown in U. S. Patent 1,788,261.
This invention is directed to a novel can made preferably from thin sheet metal stock, in which the bottom is initially permanently convexed outwardly, the bottom being provided with a plurality of feet or dimples of predetermined design and spacing to provide a good pressure vessel and a stable base for the can while being processed through a filling operation and also to provide a can which meets accepted standards of stability of a flat bottom can such that it will not easily tip and will withstand normal abuse of transport and stacking.
A construction in accordance with the present invention comprises a thin metal pressure container which, when in an unpressurized state, comprises a body providing a side wall, a permanently outwardly convexed bottom wall integral with the body, and a plurality of preformed :

~S;~0~L2 pressure-resistant, outwardly projecting, asymmetrical shallow seating dimples having inner and outer wall portions formed on the bottom wall and having lower end portions projecting below the bottom wall and providing seating sur-faces for the container disposed in close proximity to the side wall. The dimples have shallow blending transition areas with the bottom wall of relatively shallow angles to the bottom wall to provide blunt interior corners with the bottom wall to facilitate spraying of coatings onto the con-tainer bottom wall and within the dimples and to inhibit distortion when the container is pressurized, whereby the bottom is substantially nondistendible to prevent fracture of the coating upon pressurization of the container.
More specifically, the invention comprehends a noval container having a permanently formed convex base of thin sheet aluminum stock such as H19-3004 of about .0120 gauge which grows slightly under preqsure but which has memory and returns to its original shape when depressurized.
Another ob]ect is to provide a can which with the new bottom has a can height the same as convention cans so that it is compatible with vending machine requirements.
A different object is to provide a can in which the body wall thickness is minimized and the upper seaming flange is thicker than the body walls and the bottom wall, being thicker than the body wall, thus strategically allocating the material in the can as required.
These and other objects and advantages inherent in and encompassed in the invention will become more apparent from the specification and drawings, wherein:
Figure 1 is a perspective view of a can embodying one form of the invention;
Figure 2 is a side elevation thereof :~15;20~2 Figure 3 is a top plan view thereof, Figure 4 is on the same sheet as Figure 8 and is a bottom plan view thereof, Figure 5 is a fragmentary axial section taken on line 5-5 of Figure 4;
Figure 6 is a fragmentary side elevat.ion of a can embodying another form of the invention, Figure 7 is a bottom plan view of the can shown in Figure 6, Figure 8 is a bottom plan view of another embodi-ment of the invention, Figure 9 is a bottom plan view of still another embodiment;
Figure 10 is a bottom plan view of still another embodiment, and Figure 11 is an enlarged fragmentary cross-section taken substantially on line 11-11 of Figure 10.

- 2a -~; , 115~0~2 The inven~ion as shown in Figures 1-5 comprises a metal can made of H19-3004 aluminum or the like, which is drawn and wall-ironed. It comprises a thin wall body portion 3 of the order of .0047 inches which at its upper end 4 i5 about .0073 inches thick. The bottom 5 has an outwa~dly convexed generally spherical countour of about 4-7/8 inch radius and has a thickness of about .0115 inches to .0123 inches and about its periphery merges in a 1j8 inch radius with the lower edge of the side wall of the body.
The bottom 5 is formed with a plurality of hollo~
outwardly bulged generally oval shaped lopsided dimples or feet 6 which project below the bottom surface 11. In a 210.5 diameter container, six feet are provided spaced diametrically from each other center to center about 1~7S inches. Each dimple has a cusp 7 of about .218 inch radius and merges on its internal side in a steep sided wall portion 9a with the bottom wall surface 9 in a radius of about .100 inches.
The upper portion 8 of the container body wall with the flange portion 4 is triple-necked to reduce the diameter of the top end of the container. An end member 10 is double seamed at 12 to the portion 4 of the body. .
The end panel comprises an openable segment 14 which is defined by a score 15 adapted to be ruptured by lifting a lever tab 16 which has a hinge lug secured by a rivet 17 to the end panel as is well known in the art. This is due to the stepped arrangement obtained by three necked in annular portions 18, 20 and 22 and the provision of the intervening frusto-conical juncture bands 24, 25 and 26, which are of relatively shallow conical angle not exceeding substantially 30 axial. The positioning of the necked in regions adjacent to the end of the body obtains axial loading strength in the can body within require parameters.

~15~2 It will be seen tha-t the outer walls 9a of each dimple is more abrupt or extends axially at an abrupt angle to the bottom 5 than the inner wall portion 30 of each dimple which merges with wall 5 at a relativeLy shallow a~gle of about 11-12 whereas wall 9a is closer between 30-47.
Thus, the seating area 32 of each dimple is dis-posed as far as possible toward the peripheral edge 34 defined by Lhe juncture of the bottom wall and side -~all 3.
In the container illustrated, the inner concave o side 35 of each dimple provides smooth transition surface areas allowing the spraying and deposition of coatings onto the entire bottom inside surface area. Sharp angled contours preclude and inhibit good even application of the coating.
Figure 5 illustrates tooling including an anvil 37 with a concave upper face 38 and an opposing main punch 3 with a concave matching face 40 to form the wall 5 there-between. Periodically a plurality of concave pockets 42 are formed in the anvil and an opposing punch 44 is slidable within guide bores 45 in the punch 39. The forming face 46 on the punch 44 is convex and opposes a forming face 48 in pocket 42. The punches 39 and 44 advance and retract with respect to the surfaces 38 and 48 and form the metal of the bottom wall 5 therebetween.
Description of Figures 6 and 7 In this embodiment as well as in all subsequent em-bodiments, parts corresponding to those of the embodiment of Figures 1-5 are identified by the same reference numeral.
The distinction of this modification is in the pro-vision of hemispherical dimples 50,50 which project from the initially preformed outwardly convexed bottom 5. The dimples are equally spaced in an annular series and are eight in number. They project below the bottom surface 11.

11~20:~2 Embodiment of Figure 8 In this embodiment, the kidney-shaped dimples 60, 60 are four in number equally spaced along the periphery 34, each is convexed outwardly and presents a seating area 62 offset toward the periphery 54. Outer wall 63 of each dimple is steeper than the inner wall 64.
Embodiment of Figure 9 Figure 9 is similar to Figure 8 except that the kidney-shaped dimples 70 are longer and are three in number, arranged in an annular series. The seatiny areas 71 are offset toward periphery 34 and the outer walls 72 are steeper than the inner walls 74. The pronounced arcuate shape of the inner walls obtains added strength which is also true of the inner walls 64 of Figure 8.
Embodiment of Figures 10 and 11 In Figure 10, a toroidal continuous ring 80 is provided which in cross-section is non-symmetrical and has an outer wall 82 which is steeper than inner wall and presents a seating area 85 offset toward periphery 34.
Thus in each embodiment the feet or dimples extend below the spherical bottom and the seating area is offset within practical limits toward the periphery 34 consistent with the requirements of adequate strength and having non-sharp easy flowing interior surface contours which are easy to spray with coating layers or other materials.

1~5;~0~2 SUPPLEMENTARY DISCLOSURE
The aim of the present Supplementary Disclosure is to provide a further range of angles of the walls of the dimples.
It is a further aim thereof to provide more specific information regarding the coating materials utilized ~or the container.
The inner wall portion 30 of each dimple merges with the bottom side of wall 5 at a relatively shallow angle of 11 to 16, whereas wall 9a is disposed between 30 - 35.
Thus, the angles of the top sides of the inner and outer walls with the top side of wall 5 are about 165 and 147, respectively, and the corners or apices are blunt.
The coating layers utilized for coating the interior surface contours could be of two basic types of epoxy urea formaldehyde material such as sold by the Midland Division of the Dexter Corporation, in Waukegan, Illinois, as item VF1077 - Clear Coating, and the other is a water borne epoxy copolymer with acrylic, such as sold by Glidden Coatings &
Resins, a division of SoM Corporation, of Cleveland, Ohio, as their No. 640-C-552 under the trade mark "Aquature".

.~

Claims

The embodiments of the invention in which an exclu-sive property or privilege is claimed are defined as follows:

1. A thin metal pressure container, described in unpressurized state, comprising a body providing a side wall, a permanently outwardly convexed bottom wall integral with said body and a plurality of preformed pressure-resistant outwardly projecting asymmetrical shallow seating dimples having inner and outer wall portions formed on said bottom wall and having lower end portions projecting below said bottom wall and providing seating surfaces for said container disposed in close proximity to said side wall, said dimples having shallow blending transition areas with said bottom wall of relatively shallow angles to said bottom wall to provide blunt interior corners with the bottom wall to facilitate spraying of coatings onto said container bottom wall and within said dimples and to inhibit distortion upon pressurizing of the container, said bottom being substantial-ly nondistendible to prevent fracture of said coating upon pressurization of said container.

2. The invention according to claim 1, and said outer wall portions disposed at an angle of about 33° to the bottom side of said bottom wall.

CLAIMS SUPPORTED BY THE SUPPLEMENTARY DISCLOSURE

3. The invention according to claim 1, and said dimples having outer and inner wall portions and the included angle between said inner wall portions and the bottom side of the bottom wall being approximately 15°.

4. The invention according to claim 2, and said outer wall portions being disposed at an angle of about 33° to said bottom wall.

5. The invention according to claim 2, and the angle between the top side of the bottom wall and top sides of the inner and outer wall portions being approximately 165° and 147°, respectively.