AU2016232576A1

AU2016232576A1 - Can body

Info

Publication number: AU2016232576A1
Application number: AU2016232576A
Authority: AU
Inventors: Alexander Kolb; Norbert Mertens; Willem Leendert Pieter Van Dam; Ralf WERSUHN
Original assignee: Ball Beverage Packaging Europe Ltd
Current assignee: Ball Beverage Packaging Europe Ltd
Priority date: 2015-03-13
Filing date: 2016-02-25
Publication date: 2017-11-02
Also published as: CN107735331A; WO2016146362A1; WO2016146362A9; DE102015204654A1; BR112017019318A2; CA2979582A1; EP3268287A1

Abstract

The invention relates to a can body for a beverage can. The can body is formed in one piece from sheet metal and comprises a circumferential wall as a side wall and a can bottom which has a calotte-shaped central section which is curved inwards and a standing section which surrounds the central section in an annular manner and curves outwards. The standing section curved outward is connected to the circumferential wall by means of an outer transition section extending aslant in the cross-section and defines a standing ring, along which the standing section at least approximately touches a flat surface when the can body is placed on such a flat surface. The geometry of the bottom is defined by three partial radii R3a, R3b and R3c, which describe the geometry of a standing ring as part of the standing section curved outwards and have the following dimensions: 0.8 < R3a < 1.2 mm, 1.2 < R3b < 1.6 mm, and 2.0 < R3a < 3.0 mm.

Description

Can body

The invention relates to a single-piece can body, in particular, for beverage cans.

So-called two-part beverage cans, consisting of a can body and a lid, wherein the can body and lid are typically connected to each other in a leak-tight manner by a double fold, are known. The lid itself can for its part again be multipart, and typically has at least one pull tab or a resealable closure.

The can body itself is shaped in one piece and from an originally flat aluminum or steel sheet. The methods and tools for shaping a can body from sheet metal by means of stretchforming are fundamentally known. It is also known that typical can bodies for beverage cans have an inwardly curved bottom in order to endow the bottom with compressive strength. In the region of the (prior to filling) open end of the can body, the can body is typically provided with a tapered “neck”, i.e. is somewhat necked-in.

The geometry of the bottom section is selected so that cans filled with, for example, carbonated acidic beverages can withstand a high internal pressure on the order of 6 bar, without the bottom extending outward beyond a tolerable amount. Occurrence thereof is called a “bulging bottom”, and is the result of deformation of the bottom due to an internal pressure prevailing in the can.

The aim in the designing of a can body is typically to obtain sufficiently high strength with least possible material usage and production complexity.

The present invention also addresses this problem.

The present invention proposes a can body for a beverage can, wherein the can body is formed in one piece from sheet metal, and comprises a circumferential wall serving as a side wall and a can bottom having a cup-shaped inwardly curved central section and a standing section that surrounds the central section in an annular manner and is curved outwardly. The outwardly curved standing section is connected to the circumferential wall via an outer transitional section extending aslant in the cross-section, and defines a standing ring along which the standing section at least approximately touches a flat surface when the can body is placed on such a flat surface.

The geometry of the bottom is determined by • at least one first radius R1 that describes the curvature of the inwardly curved central section, • at least one second radius R2 that describes the geometry of a transition from the inwardly curved central section to the standing section, • at least one third radius R3 that describes the geometry of a standing ring as part of the outwardly curved standing section, and • at least one fourth radius R4 that describes the geometry of an inwardly curved, circumferential bead on the outside of the standing section.

According to the present invention, the geometry of the standing ring is defined by three partial radii R3a, R3b, and R3c that have the following measurements: 0.8 < R3a < 1.2 mm 12 < R3b < 1.6 mm 2.0 < R3a < 3.0 mm

Between the second radius R2 and the partial radius R3a, there is provided a section IL that is straight in sectional view, extends from the second radius R2 to the partial radius R3a, and defines a frustoconical section of the bottom.

Preferably, the partial radii R3a, R3b, and R3c have an approximate ratio of 3:4:9 (R3a : R3b : R3c).

The bottom geometry according to the present invention is based on the finding that cans for which bottom bulging is deliberately induced or pre-formed, whether pneumatically, hydraulically, or mechanically, depending on the standard bottom-shaping process, have a lower potential of deformation or bottom bulging. Such pre-forming is, however, not practicable with an acceptable level of effort. The geometry according to the present invention can be produced in a conventional manner, and provides similarly little bottom bulging as with preformed can bodies. This improvement is not achieved by changing the manufacturing process, but by redesigning the tools.

The sheet metal of the can body is preferably sheet steel. Alternatively, the sheet metal is aluminum sheet.

If sheet steel, the sheet metal of the can body preferably has, in the region of the cupshaped inwardly curved central section, a maximum sheet thickness of less than 0.205 mm, preferably less than 0.200 mm.

The inwardly curved central section is preferably completely concave when viewed from the outside, and forms a cup that extends to the standing section.

The outer diameter of the side wall preferably amounts to between 51 and 68 mm, e.g., about 53 or 58 mm, or 66 mm. Preferred diameters of 51 to 55 mm, 56 to 60 mm, and 64 to 68 mm.

Preferably, the geometry of the bottom is additionally defined by at least one fifth radius R5 that describes the geometry of a transition from the standing section to the side wall, and is between 2.5 and 7.5 mm.

The geometry of the cup-shaped inwardly curved central section is preferably defined by two first partial radii R1a and R1b, of which the partial radius R1a is between 30 and 55 mm, and the partial radius Rb is between 15 and 55 mm.

The second radius R2 preferably amounts to between 1.5 and 3 mm. The fourth radius R4 preferably amounts to between 2 and 5 mm. A tangent to the second radius R2 and the partial radius R3a at the transition from the second radius R2 into the partial radius R3a is preferably inclined inwardly at an angle alphal relative to the longitudinal axis of the can body. The angle alphal preferably amounts to between 3° and 15°. Between the second radius R2 and the partial radius R3a, the geometry of the bottom has a section IL that is straight in sectional view, and that extends from the second radius R2 to the partial radius R3a and preferably has a length between 1.7 and 2.5 mm, for example, 2.1 mm. The straight section IL is inclined inwardly (as seen from the standing plane) by the angle alphal—i.e., preferably between 3° and 15°—relative to the longitudinal axis of the can body. The straight section IL thus describes a truncated cone having a conical angle (as the opening angle of the associated cone) of between 6° and 30°. A tangent to the partial radius R3c and the radius R4 at the transition from the partial radius R3c into the radius R4 is preferably inclined outwardly at an angle alpha2 relative to the longitudinal axis of the can body. The angle alpha2 preferably amounts to between 10° and 40°, in particular, between 15° and 30°, for example, about 19°. A tangent to the fourth radius R4 and the fifth radius R5 at the transition from the fourth radius R4 to the fifth radius R5 is preferably inclined upwardly by an angle alpha3 relative to a standing plane defined by the standing ring, wherein the angle alpha3 is between 25° and 40°.

It should be noted here that the standing ring touches a planar surface along a circular standing line, when the can body is placed on the planar surface. The standing line simultaneously defines a standing plane that runs perpendicularly to the central longitudinal axis of the can body.

Preferably, the partial radius R3b extends over an angle alpha R3b that is between 10° and 60°, in particular, between 25° and 45°, and, in particular, about 36°.

Preferably, the partial radius R3a ends at the standing lane, and transitions there in a continuously differentiable manner (i.e., without kinks, and thus in a smooth manner) into the partial radius R3b. A tangent to the partial radius R3a and the partial radius R3b at the transition from the partial radius R3a to the partial radius R3b consequently runs in the standing plane defined by the standing line.

It is also preferred if the center points of the partial radii R3a and R3b are located at least approximately on a perpendicular to the standing plane that runs through the standing line.

The completed (final) geometry of the bottom is produced solely by deep-drawing, without subsequent reforming, as can be recognized at the straight section IL, thus standing in contrast to a geometry such as is described, for example, in DE 10 2013 226 032 A1.

The aforementioned problem is preferably also solved by a can, in particular, a beverage can that has a can body of the above-described type, and also a lid that is connected to the can body via a double fold. The lid has a central lid panel having a tear-open panel arranged therein. Fastened to the lid—in particular, the lid panel—is a tear-open tab for tearing open the tear-open panel, for example, a so-called stay-on tab. Such a can has very little bottom bulging, on the order of less than 1 mm, even with high internal pressure on the order of 6 bar. The can preferably has a nominal volume of 330 mL. Accordingly, the can body is also dimensioned so as to lead to a can having a fill volume of 330 mL.

The invention shall now be described by means of an embodiment, with reference to the drawings. In the drawings,

Fig. 1 illustrates a perspective overall view of a beverage can having a can body according to the invention;

Fig. 2 illustrates a side view of a can body according to the invention for a beverage can having a fill volume of 330 mL;

Fig. 3 illustrates a side view of a can body for a beverage can having a fill volume of 355 mL;

Fig. 4 illustrates a detail view of the bottom geometry of the can bodies from fig. 2 and 3; and

Fig. 5 illustrates the detail view from fig. 4 in another manner of representation.

The beverage can 10 depicted in fig. 1 has a can body 12 and a lid 16 connected to the can body 12 via a double fold 14; the lid has, in the usual manner, a central lid panel 18 in which a tear-open panel 20 is arranged and to which a tear-open tab 22 with which the tear-open panel 20 is to be opened is fastened. The tear-open tab 22 (also called an opener tab) may be, for example, a so-called stay-on tab that remains connected to the lid 16 even after the tear-open panel 20 has been opened.

Fig. 2 and 3 illustrate side views of the can body 12 before being closed with a lid 16.

The can body 12 is formed in one piece, from originally-flat aluminum or steel sheet metal, and comprises a circumferential wall 24 serving as a side wall and a can bottom 30 having a cupshaped inwardly curved central section 32 and a standing section 34 that surrounds the central section in an annular manner and is curved outwardly. The outwardly curved standing section is connected to the circumferential wall 24 via an outer transitional section 36 extending outwardly aslant in the cross-section, and defines a standing ring 38 along which the standing ring at least approximately touches a flat surface when the can body is placed on such a flat surface. The line along which the standing ring touches the planar surface is also called a standing line within this description, and is circular. The standing line defines a standing plane that runs perpendicularly to a central longitudinal axis of the can body 12. The cup-shaped inwardly curved central section 32 has the greatest distance from the standing plane in the middle thereof. This distance, referred to as the bottom depth DD, preferably amounts to between 8 and 12 mm. The diameter of the standing ring—more precisely, the diameter DS of the circular standing line—is preferably between 40 and 48 mm.

The geometry of the bottom (bottom geometry) is depicted in fig. 4, in the detail. The cup-shaped inwardly curved central section 32 of the bottom 30 has a geometry that is defined by at least one first radius R1. In the embodiment, the geometry of the cup-shaped inwardly curved central section 32 of the bottom 30 is defined by two partial radii R1a and R1b, of which the first partial radius R1a is about 48 mm and the other second partial radius R1b is about 41 mm.

The cup-shaped inwardly curved central section 32 transitions, in a second radius R2, into the standing section 34. The second radius R2 amounts to about 2 mm in the embodiment.

The standing ring 38, the geometry of which is defined by at least one third radius R3, connects to the second radius R2. In the embodiment, and according to the invention, the geometry of the standing ring 38 is defined by three partial radii R3a, R3b, and R3c. The partial radius R3a is about 1.1 mm in the embodiment, the partial radius R3b is about 1.4 mm in the embodiment, and the partial radius R3c is about 2.5 mm in the embodiment.

Connecting to the standing ring 38 is an inwardly curved, circumferential bead, the geometry of which is defined by a fourth radius R4 that, in the embodiment, is about 2.8 mm. Finally, the standing section 34 transitions, in a fifth radius R5, into the side wall 24 of the can body 12. The fifth radius R5 amounts to about 5 mm.

In addition, the bottom geometry is also defined by the fact that the second radius R2 transitions smoothly into the partial radius R3a, and that there is, at this transition, a tangent to the second radius R2 and the partial radius R3a, which is inclined inwardly at an angle of about 6° relative to the central longitudinal axis of the can body 12.

Between the second radius R2 and the partial radius R3a, the bottom geometry has a section IL that is straight in sectional view, and that extends from the second radius R2 to the partial radius R3a and preferably has a length between 1.9 and 2.3 mm. In the embodiment depicted, the length of the straight section IL amounts to 2.1 mm. The straight section IL is inclined inwardly by the angle alphal—i.e., by about 6°—relative to the longitudinal axis of the can body, starting from the standing plane. The straight section IL thus describes a truncated cone having a conical angle (as the opening angle of the associated cone) of about 12°, and a height of about 2.1 mm.

The standing ring 38 transitions smoothly into the inwardly curved circumferential bead. At this transition, the partial radius R3c transitions into the fourth radius R4. The tangent to these radii is inclined outwards by about 19° relative to the central longitudinal axis of the can body 12.

The fourth radius R4 transitions smoothly into the fifth radius R5. At this transition, there exists a tangent to the two radii R4 and R5, which is inclined upwardly by about 32° relative to the standing plane.

Moreover, the geometry of the standing ring 38 is also defined by the fact that the radius R3b extends over an angle of about 36°. This angle begins at the standing line and extends outward. At the standing line, the partial radius R3a transitions smoothly into the partial radius R3b. A tangent to this transition runs in the standing plane, and therewith perpendicular to the central longitudinal axis of the can body 12.

Such a bottom geometry endows a beverage can having a diameter of preferably about 58 mm—with the use of thin sheet metal with sheet thicknesses, of about 0.205 mm, 0.200 mm, and smaller, specifically 0.195 and 0.190 mm—with such a strength in the bottom region that there occurs a bottom bulging of less than 1 mm even at high internal pressure.

List of reference signs 10 Beverage can 12 Can body 14 Double fold 16 Lid 18 Central lid panel 20 Tear-open panel 22 Tear-open tab 24 Side wall 30 Can bottom 32 Central section 34 Standing section 36 Transitional section 38 Standing ring

Claims

Claims

1. A single-piece can body for a beverage can, having an opening, a side wall, and a bottom that connects to the side wall and has a cup-shaped inwardly curved central section as well as an outwardly curved standing section that connects to the inwardly curved central section and surrounds same in an annular manner, the side wall connecting to the standing section, wherein the can body has a central longitudinal axis and the geometry of the bottom is defined by • at least one first radius R1 that describes the curvature of the inwardly curved central section, • at least one second radius R2 that describes the geometry of a transition from the inwardly curved central section to the standing section, • at least one third radius R3 that describes the geometry of a standing ring as part of the outwardly curved standing section, and • at least one fourth radius R4 that describes the geometry of an inwardly curved, circumferential bead on the outside of the standing section, characterized in that the geometry of the standing ring is defined by three partial radii R3a, R3b, and R3c that have the following measurements: 0.8 < R3a < 1.2 mm 1.2 < R3b < 1.6 mm 2.0 < R3c < 3.0 mm wherein, between the second radius R2 and the partial radius R3a, there is provided a section IL that is straight in sectional view, extends from the second radius R2 to the partial radius R3a, and defines a frustoconical section of the bottom.
2. The can body according to claim 1, characterized in that the partial radii R3a, R3b, and R3c are in an approximate ratio of 3:4:9 (R3a : R3b : R3c).
3. The can body according to claim 1 or 2, characterized in that the side wall has a diameter between 51 and 68 mm.
4. The can body according to at least one of claims 1 to 3, characterized in that the sheet metal of the can body is sheet steel.
5. The can body according to at least one of claims 1 to 4, characterized in that the sheet metal of the can body in the region of the cup-shaped inwardly curved central section has a maximum sheet thickness of less than 0.205 mm, preferably less than 0.200 mm.
6. The can body according to at least one of claims 1 to 5, characterized in that the geometry of the bottom is defined by at least one fifth radius R5 that describes the geometry of a transition from the standing section to the side wall, and is between 2.5 and 7.5 mm.
7. The can body according to at least one of claims 1 to 6, characterized in that the geometry of the cup-shaped inwardly curved central section is defined by two first partial radii R1a and R1b, for which the following applies: 30 < R1a < 55 mm 15 < R1b < 55 mm
8. The can body according to at least one of claims 1 to 7, characterized in that the second radius R2 amounts to between 1.5 and 3 mm.
9. The can body according to at least one of claims 1 to 8, characterized in that the fourth radius R4 amounts to between 2 and 5 mm.
10. The can body according to at least one of claims 1 to 9, characterized in that section IL that is straight in sectional view is inclined inwardly at an angle alphal relative to the longitudinal axis of the can body, wherein the angle alphal is between 3° and 15°.
11. The can body according to at least one of claims 1 to 10, characterized in that a tangent to the partial radius R3c and the radius R4 at the transition from the partial radius R3c to the radius R4 is inclined outwardly by an angle alpha2 relative to the longitudinal axis of the can body, wherein the angle alpha2 is between 10° and 40°, preferably between 15° and 30°, and especially preferably about 19°.
12. The can body according to claim 6 and at least one of claims 1 to 5 and 7 to 11, characterized in that a tangent to the fourth radius R4 and the fifth radius R5 at the transition from the fourth radius R4 to the fifth radius R5 is inclined upwardly by an angle alpha3 relative to a standing plane defined by the standing ring, wherein the angle alpha3 is between 25° and 40°.
13. The can body according to at least one of claims 1 to 12, characterized in that the partial radius R3b extends over an angle alpha R3b that is between 10° and 60°, preferably between 25° and 45°, and especially preferably about 36°.
14. The can body according to at least one of claims 1 to 13, characterized in that the standing ring defines a circular standing line along which the standing ring touches a standing plane when the can body has been placed on a planar surface running in the standing plane, wherein the partial radius R3a ends at the standing line and transitions there in a continuously differentiable manner into the partial radius R3b.
15. The can body according to claim 14, characterized in that the center points of the partial radii R3a and R3b are located at least approximately on a perpendicular to the standing plane that runs through the standing line.
16. The can body according to at least one of claims 1 to 15, characterized in that the straight section IL has a length of between 1.7 and 2.5 mm.
17. A can having the can body according to at least one of claims 1 to 16, and a lid connected to the can body by a double fold, which has lid cover to a tear-open panel and a tear-open table fastened to the lid panel.