EP3969380A1

EP3969380A1 - Lightweight beverage can made from aluminum alloy

Info

Publication number: EP3969380A1
Application number: EP20740700.8A
Authority: EP
Inventors: Alireza Arbab; Thierry BAYLE; Mircea CABLEA; Laurent LASZCZYK
Original assignee: Constellium Neuf Brisach SAS; Constellium Muscle Shoals LLC
Current assignee: Constellium Neuf Brisach SAS; Constellium Muscle Shoals LLC
Priority date: 2019-05-13
Filing date: 2020-05-12
Publication date: 2022-03-23
Also published as: US20220242605A1; WO2020229767A1

Abstract

The invention relates to a beverage can on the basis of an aluminum alloy, preferably for a carbonated drink, comprising: - a body (6) having a cylindrical shape and an outer diameter D1; - a concave dome-shaped bottom (1) having a depth H1 at its center, an outer diameter D3 and a rectilinear part (2) having a height H3; - a convex lower ring (7) having a bearing diameter D2 and a flat surface with a width L2; - an outer shoulder (5) of radius R1; - a comb (4) connecting the outer shoulder (5) and the lower ring (7). The invention is characterized in that the thickness of the sheet of the dome is from 180 to 230 μm, preferably from 190 to 220 μm; and in that the outer diameter D3 of the concave dome (1) is from 36 to 44 mm, preferably from 37 to 43 mm; and in that the width of the lower ring L4 is from 3 to 4.5 mm, preferably from 3.3 to 4 mm; and in that the lower ring has concave deformations (8) which are distributed at regular intervals along the lower ring (7).

Description

DESCRIPTION

Title: Lightened beverage tin in aluminum alloy TECHNICAL FIELD

The technical field of the invention is that of beverage cans, in particular carbonated drinks, based on aluminum or an aluminum alloy. Figure 1 shows a sectional diagram of a beverage can half bottom. Referring to Figure 1, a beverage can generally comprises a beverage can body 6, a dome 1, a lower ring 3, a rectilinear part 2 of the dome 1 and a comb 4 connecting the lower ring and the body of the drink box. PRIOR ART

There is prior art provided in the field of beverage cans to solve various technical problems. For example, US Pat. No. 4,685,582 of National Can Corporation is known, which describes a solution for improving the compatibility between the bottom and the cover of beverage cans with the aim of being able to stack the beverage cans easily during their transport and their storage.

US patent 5,680,952 to Bail Corporation is also known, which describes a beverage can having particular dimensions, as well as deformations on the dome of the bottom of the beverage can.

There are also several documents describing convex or concave deformations on the dome of the bottom of the beverage can and / or the oblique lower edge of the bottom of the beverage can. Mention may in particular be made of US patent 4,953,738 to Stirbis, US patent application 2008/0029523 to Rexam Beverage Can, or else US patent 7,185,525 to Elmer.

Also known is US Pat. No. 4,732,292 to Schmalbach-Lubeca GmbH, which describes concave deformations on the bottom of the beverage can, distributed over at least two concentric circles of different diameters.

Patent application EP 0 302 412 of Pac International Inc. is also known, which describes a particular structure for the bottom of a beverage can with a series of shelves and flat parts.

Despite all these solutions, manufacturers are constantly in search of cost reduction, focusing in particular on reducing the thickness of the metal alloy used for the manufacture of beverage cans. This reduction in thickness raises many problems, which can be for example the shaping and the mechanical resistance of the beverage can (axial resistance, resistance to internal pressure, resistance to falling, etc.).

The resistance to internal pressure, which is one of the main properties sought, can be characterized by a test consisting in increasing the internal pressure (= pressure inside the beverage can). This test makes it possible to identify two values known to those skilled in the art: the overturning pressure, which corresponds to the maximum pressure observed when the dome is overturned, and the increase in the height of the beverage can after a pressure cycle. typical (increase from 0 to 6.2 bar, then decrease to 3.5 bar). This increase in the height of the beverage can corresponds to the residual deformation caused by the increase in pressure and which persists even after the decrease in internal pressure. As illustrated in the examples below (see Figures 12 and 13), the inventors propose two curves representing the increase in the height of the beverage can (measured at the level of the lower ring) as a function of the internal pressure for the purpose. to determine these two values and to understand the associated physical phenomena.

A theoretical example of such a curve is given in Figure 2 of the present description. This curve can be described by three stages I, II and III corresponding to distinct deformation mechanisms of the beverage can a, b and c, as illustrated in FIG. 3 of the present description. A first linear stage, called stage I on the curve of Figure 2, corresponds to an elastic deformation characterized by a slight swelling of the dome and a rotation of the oblique edge (respectively a and b of Figure 3). At this point, if the internal pressure is removed, the dome and oblique edge can return to the original position. This stage I is not very sensitive to the reduction in thickness of the bottom of the beverage can.

A second linear stage, called stage II on the curve in Figure 2, corresponds to the start of plastic deformation of the dome (a in Figure 3) characterized by the irreversible unfolding of the radius of the lower ring (c in Figure 3) ), as well as an amplified swelling of the dome. At this point, if the pressure is removed, the dome no longer returns to its initial position and there is residual deformation of the lower ring. This stage II is sensitive to the reduction in thickness of the bottom of the beverage can: the resulting deformation of the pressure increases when the thickness decreases, which limits the possibilities of reducing the thickness.

Finally a third stage, called stage III on the curve of Figure 2, corresponds to a dramatic and irreversible deformation of the dome, that is to say that at this stage a minimal amount of additional pressure compared to stage II leads to a very important deformation of the dome, the oblique edge and the lower ring (respectively a, b and c in Figure 3) which persists even after pressure decrease. The thickness of the initial sheet, which is changed very little during the shaping of the dome of the drink can with a thinning of the order of 2 to 5%, and which therefore corresponds approximately to the thickness of the sheet of the dome, is chosen such that the overturning pressure is greater than the maximum internal pressure observed during the production, transport or storage of beverage cans, typically 90 pound-force per square inch (psi) (i.e. approximately 6.2 bars).

The axial resistance, which is another of the main properties sought, can be characterized by a test consisting in applying a vertical force downwards on the upper end of the beverage can, empty and without a cover, when the latter is placed vertically. on a flat surface. The geometry of the bottom of the beverage can as well as the thickness of the sheet are chosen such that the location of the dramatic and irreversible deformation during the increase in the applied vertical force, characterized by an inflection of the force versus curve. displacement, always takes place at the level of the body of the beverage can and for a force greater than the values observed during the production, transport or storage of the beverage cans, namely generally 200 pounds (Ibs) (i.e. approximately 900 Newton (N )).

DISCLOSURE OF THE INVENTION

In this context of reducing the thickness of the initial aluminum alloy sheet used for the manufacture of beverage cans put into perspective with the resistance to internal pressure, the inventors have developed a beverage can capable of maintaining, or even reducing, 'improve the resistance to internal pressure, despite the reduction in thickness of the initial aluminum alloy sheet.

Currently, the initial aluminum alloy sheet thicknesses for beverage cans are generally about 260 µm in the United States and about 245 µm in Europe. The initial aluminum alloy sheet thicknesses targeted according to the present invention are of the order of 200 to 230 μm, or approximately 6 to 18% reduction in thickness in Europe and approximately 11 to 23% in the United States. .

The technical problem solved according to the present invention is therefore to reduce the thickness of the initial aluminum alloy sheet used for the manufacture of beverage cans, for example by 5 to 25% compared to what is usually practiced in the field of beverage cans (about 15 to 60 µm reduction), while improving the resistance to internal pressure compared to a conventional beverage can obtained from a thinned sheet and while maintaining the resistance to internal pressure compared to to a conventional commercial beverage can, and while retaining satisfactory axial resistance (to vertical force). It should be noted that the reduction in thickness of the initial aluminum alloy sheet used for the manufacture of beverage cans ultimately makes it possible to lighten the beverage cans by 2 to 15%, knowing that the bottom of the beverage can , which retains the initial thickness of the aluminum alloy sheet, generally accounts for more than 30% of the total weight of the beverage can.

In addition to the resistance to internal pressure, those skilled in the art are also faced with problems of resistance to vertical force during the manufacture and filling of beverage cans, as well as the crimping of the lid. It should be noted that the present invention, which makes it possible to limit the deformations undergone by the cans during their life cycle because of the internal pressure, also has the advantage of maintaining a resistance to the vertical force with respect to a box. classic commercial drink.

A first object of the invention is a beverage can based on an aluminum alloy, preferably for a carbonated drink, comprising (see Figures 4 to 11):

- a body 6 of cylindrical shape having an external diameter DI;

a bottom in the form of a concave dome 1 having a depth H1 at its center, an external diameter D3 and a rectilinear part 2 of height H3;

a convex lower ring 7 having a bearing diameter D2 and a flat of width L2;

- an outer shoulder 5 of radius RI;

- a comb 4 connecting the outer shoulder 5 and the lower ring 7;

characterized in that the thickness of the dome sheet is 180 to 230 µm, preferably 190 to 220 µm;

and in that the outer diameter D3 of the concave dome 1 is 36 to 44 mm, preferably 37 to 43 mm;

and in that the width of the lower ring L4 is 3 to 4.5 mm, preferably 3.3 to 4 mm; and in that the lower ring comprises concave deformations 8, distributed at regular intervals along the lower ring 7.

A second object of the invention is a method of manufacturing a beverage can according to the present invention, comprising the following successive steps:

- Supply of an aluminum alloy, for example AA3104, for example in the metallurgical state H14 or H19, in the form of a strip with a thickness of 180 to 230 μm, preferably 190 to 220 μm;

- cutting of discs called blanks in the aluminum alloy strip;

- Stamping and stretching of the blanks to obtain a beverage can body, using tools suitable for forming the beverage can as described in the present application; - Manufacture of a cover with another aluminum alloy, for example AA5182;

- assembly of the lid and the body of the drink can to obtain a drink can.

A third object of the invention is a tool for shaping the beverage can according to the present invention.

FIGURES

[Fig. 1] Figure 1 is a sectional diagram of a beverage can half bottom. Reference 1 corresponds to the dome of the beverage can, reference 2 to the rectilinear part of the dome, reference 3 to the lower ring, reference 4 to the oblique edge of the bottom of the beverage can, called comb, reference 5 to the outer shoulder of the body of the beverage can and the reference 6 to the body of the beverage can.

[Fig. 2] Figure 2 is a theoretical curve illustrating the increase in the height of the beverage can, measured at the level of the lower ring, as a function of the internal pressure, that is to say the pressure inside. of the drink can. Reference I corresponds to a stage of reversible deformation, reference II to a stage of non-reversible deformation, which could adversely affect the filling, stability or stackability of the beverage can, and reference III at a stage where the dome turns over. In stage III, the beverage can is then no longer stable, that is to say that it can no longer stand upright, and it is no longer stackable.

[Fig. 3] Figure 3 is a sectional diagram of a beverage can half-bottom illustrating the different stages of deformation as a function of the increase in internal pressure. The solid line (stage 0) corresponds to the undeformed beverage can. The dashed line corresponds to the limits of the bottom of the beverage can when transitioning from stage I to stage II in Figure 2. The dotted line corresponds to the limits of the bottom of the beverage can when transitioning from stage II to stage III in Figure 2. The reference "a" corresponds to the deformation of the dome, the reference "b" to the deformation of the oblique edge, and the reference "c" to the deformation of the lower ring.

[Fig. 4] Figure 4 is a sectional diagram of a beverage can half-bottom according to the present invention, and in particular according to Example 1 below. In this figure, the references 1, 2, 4, 5 and 6 are the same as those described in connection with Figure 1 above. Reference 7 corresponds to the lower ring according to the present invention and reference 8 to a concave deformation of the lower ring (for example a rib).

[Fig. 5] Figure 5 is a sectional diagram of a beverage can half-bottom according to the present invention, and in particular according to Example 1 below. In this figure, the reference DI corresponds to the external diameter of the beverage can, D2 to the support diameter of the lower ring, on the outermost fulcrum with respect to the central axis of the dome, D3 at the external diameter of the dome (= diameter of the rectilinear part of the dome), H1 at the depth of the dome, H2 at the height of the comb, H3 at the height of the rectilinear part of the dome, Al at the angle of the rectilinear section of the comb relative to the horizontal, and RI to the radius of the outer shoulder 5, which is convex, located in the connecting portion between the body 6 of the beverage can and the comb 4.

[Fig. 6] Figure 6 is a sectional diagram of a beverage can half-bottom according to the present invention, and in particular according to Example 1 below. In this figure, the reference D4 corresponds to the diameter of the beginning of the rectilinear section of the comb, H4 to the height of the start of the rectilinear section of the comb, L1 to the width of the rectilinear section of the comb, A2 to the angle of the flat of the lower ring with respect to the horizontal, L2 to the length of the flat of the lower ring, L3 to the minimum width of the lower ring within a concave deformation, and L4 to the width of the lower ring out of concave deformations. The widths L3 and L4 are defined at a height equal to half of the height H4.

[Fig. 7] Figure 7 is a sectional diagram of a beverage can half-bottom according to the present invention, and in particular according to Example 1 below. In this figure, the reference R2 corresponds to the concave radius, located in the connecting portion between the comb and the lower ring, outside the concave deformations, before the spokes R3 and R4 described below, R3 at the convex radius, located in the connecting portion between the comb and the lower ring, outside the concave deformations, between the spokes R2 described above and R4 described below, R4 at the convex radius, located in the connecting portion between the lower ring and the rectilinear part of the dome, after the spokes R2 and R3 described above, R5 at the concave radius, located in the connecting portion between the comb and the lower ring, within the concave deformations, before the spokes R6 described above. after and R4 described above, and R6 at the convex radius, located in the connecting portion between the comb and the lower ring, within the concave deformations, between the spokes R5 and R4 described above.

[Fig. 8] Figure 8 is a diagram of a concave deformation seen from below. In this figure, the references 1, 2, 4, 5 and 6 are the same as those described in connection with Figure 1 above. References 7 and 8 are the same as those described in connection with Figure 4 above. Reference 9 corresponds to the curved section of the connecting zone between the interior of a concave deformation and a zone without concave deformation, along a horizontal section at a height equal to half the height H4.

[Fig. 9] Figure 9 is a diagram of a concave deformation seen from below. In this figure, the reference L5 corresponds to the length of the concave deformation 8, R7 to the radius concave of the curved section 9, and R8 to the convex radius of the curved section 9. The references L3 and L4 are the same as those described in connection with Figure 6 above.

[Fig. 10] Figure 10 is a sectional diagram of a beverage can half-bottom according to the present invention, and in particular according to Example 1 below. In this example, an additional dome recovery shaping operation was applied, as currently practiced on a number of commercial beverage can formats, and so that the rectilinear portion of the dome 2 is transformed with a deformation axisymmetric concave 10.

[Fig. 11] Figure 11 is a three-dimensional diagram of a section of a beverage can bottom according to the present invention, and in particular according to Example 1 below. In this figure, the references 1, 2 and 4 to 9 are the same as those described in connection with Figure 8 above.

[Fig. 12] Figure 12 is a curve showing the increase in the height of the beverage can (generally expressed in mm), measured at the highest point when the beverage can is positioned upside down, i.e. when the dome is up, as a function of the internal pressure (generally expressed in bars), that is to say the pressure inside the beverage can. It illustrates the results of digital simulations for calculating the overturning pressure for several beverage cans, as explained in the examples below. The abscissa axis is not expressed in bars but in standardized values, the value 1 corresponding to the value of the turning pressure of the reference preform C1, which is the objective that the present invention seeks to achieve at least. minus 100%. This target is represented by the gray vertical line. The ordinate axis is not expressed in mm but in standardized values, the value 1 corresponding to the box height of the reference preform C1 when it is turned over.

[Fig. 13] Figure 13 is a curve showing the increase in vertical force (usually expressed in newtons (N)), applied to the top of the beverage can during the axial strength test, as a function of vertical displacement (usually expressed in mm). It illustrates the results of numerical simulations of calculation of the axial resistance of the bottom, corresponding to the inflection point of the curve, characterizing the end of the linear section. The abscissa and ordinate axes are not expressed in mm and in N respectively, but in normalized values, the values 1 corresponding to the vertical displacement and vertical force values representing the axial resistance of the reference drink can Cl. horizontal gray corresponds to the value of 900 N (200 Ibs) discussed above in the description, which is the objective that the present invention seeks to exceed.

DETAILED DESCRIPTION OF THE INVENTION In the description, unless otherwise indicated:

- the designation of aluminum alloys conforms to the nomenclature established by The Aluminum Association;

- the contents of chemical elements are indicated in% and represent mass fractions, unless otherwise indicated.

According to the present invention, the term “convex” means oriented towards the outside of the beverage can.

According to the present invention, the term “concave” means oriented towards the inside of the beverage can.

The beverage can according to the present invention makes it possible to compensate for the loss of resistance to internal pressure due to a reduction in the thickness of the aluminum alloy sheet from which the beverage can is made.

In general, with current processes, it is considered that the maximum internal pressure that a beverage can undergoes during its manufacturing and life cycle is approximately 6.2 bars (or 90 psi). Also, it is desirable that the turning pressure is greater than 6.2 bars, that is to say of the same order of magnitude as that of the reference beverage can (C1 in the examples below) existing on the market. The inversion pressure is the pressure at which the dome of the bottom of the beverage can is inverted. This reversal is irreversible and prevents the stability and stacking of the beverage cans on top of each other.

In addition to the resistance to internal pressure, a beverage can is also preferably resistant to the axial loading (vertical force) which occurs during the various operations of shaping the shrinkage and the vertical section of the dome, as well as during filling and filling. cover crimping. It is considered, with current methods, that the beverage can body must withstand an axial force (vertical force) greater than approximately 900 N (ie 200 Ibs), without showing any damage to the bottom of the beverage can, or to any damage. the side wall. It is generally considered that this value of 900 N represents approximately 85% of the resistance of the reference beverage can (C1 in the examples below) existing on the market.

The beverage can according to the present invention makes it possible to compensate for the loss of strength due to the reduction in thickness of the aluminum alloy sheet from which the beverage can is made. In general, the beverage can according to the present invention makes it possible to limit the deformation of the bottom of the beverage can, and in particular of the dome, the lower ring and the comb, in stage II and to push back stage III (dramatic deformation ) at higher pressure levels than those requested by customers, generally 6.2 bars. The solution proposed according to the present invention comprises the combination of three characteristics having a synergistic effect:

- reduction of the outer diameter of the dome;

- increase in the width of the lower ring;

- addition of concave deformations (for example notches or ribs) at the level of the lower ring.

A first object according to the present invention is a beverage can based on an aluminum alloy, preferably for a carbonated drink, comprising:

- a body 6 of cylindrical shape having an external diameter DI;

a convex lower ring 7 having a bearing diameter D2 and a flat of width L2;

- an outer shoulder 5 of radius RI;

- a comb 4 connecting the outer shoulder 5 and the lower ring 7;

and in that the width of the lower ring L4 is 3 to 4.5 mm, preferably 3.3 to 4; mm; and in that the lower ring comprises concave deformations 8, distributed at regular intervals along the lower ring 7.

Preferably, the outer diameter ID of the body 5 of the beverage can according to the present invention is 50 to 75 mm, preferably 55 to 70 mm.

Preferably, the radius RI of the shoulder is 2 to 5 mm.

Preferably, the dome 1 of the beverage can according to the present invention has at least one of the following characteristics:

- a diameter D2 of the lower ring 3 is 39 to 47 mm, preferably 40 to 46 mm;

- a depth H1 of 7 to 12 mm, preferably 8 to 11 mm; and or

- a rectilinear part 2 of height H3 from 0 to 6 mm, preferably from 1.5 to 4 mm.

Preferably, the lower ring 7 of the beverage can according to the present invention has at least one of the following characteristics:

- a width L4 of 3 to 4.5 mm, preferably 3.3 to 4 mm;

- a flat forming an angle A2 with the horizontal towards the axis of symmetry of the drink can from 0 to 10 °; and or

- a flat having a length L2 of 0 to 2 mm.

As regards the lower ring, its geometry (for example its shape and its diameter) can be optimized to gain performance according to the applications envisaged. Likewise, the dimensions (eg height, width, radii of curvature) of the lower ring can also be optimized.

Preferably, the comb 4 of the beverage can according to the present invention has at least one of the following characteristics:

- a height H2 of 5 to 20 mm, preferably 6 to 14 mm;

- a diameter D4 of the beginning of the rectilinear section of 42 to 53 mm;

- a height H4 from the start of the rectilinear section of 1.5 to 4 mm, preferably 1.5 to

3.5; mm;

- An angle Al of the rectilinear section relative to the horizontal of 30 to 40 °; and or

- a length L1 of the rectilinear section from 0 to 13.5 mm.

Preferably, the connecting portion between the comb 4 and the lower ring 7 comprises at least one of:

- a radius R2 of 2 to 4 mm; and or

- a radius R3 of 1 to 3 mm.

Preferably, the connecting portion between the lower ring 7 and the rectilinear part 2 of the dome 1 comprises a radius R4 of 1 to 3 mm.

Preferably, the concave deformations 8 of the beverage can according to the present invention have at least one of the following characteristics:

a width L3 of 2 to 4.5 mm, preferably 2.5 to 3.5 mm;

- a length L5 of 1 to 10 mm, preferably 1 to 5 mm;

- a radius R5 of 2 to 4 mm;

- a radius R6 of 1 to 3 mm;

- a length L5 of 1 to 10 mm;

- a radius R7 of 0.5 to 4 mm;

- a radius R8 of 0.5 to 20 mm; and or

- a number N from 4 to 36, preferably from 6 to 24.

As regards the concave deformations, their shape and their number can be optimized according to the applications envisaged in order to gain in performance. In particular, the deformations concaves extend generally and preferably beyond the lower ring in the connecting portion between the rectilinear section of the comb and the lower ring.

According to current practice, the beverage can according to the present invention can, in certain cases, be subjected to a subsequent operation of taking up the dome, as described in FIG. 10. This modification of the profile of the bottom of the beverage can is generally carried out. , on current beverage cans on the market, after application and curing of the varnishes, just like the operation of shrinking in the upper part of the beverage can. It has a positive effect on the resistance to internal pressure, regardless of the characteristics of the proposed solution.

- cutting of discs called blanks in the aluminum alloy strip;

- Stamping and stretching of the blanks to obtain a beverage can body, using tools suitable for forming the beverage can as described in the present application;

- Manufacture of a cover with another aluminum alloy, for example AA5182;

- assembly of the lid and the body of the drink can to obtain a drink can.

As regards the manufacture of the beverage can according to the present invention, those skilled in the art will know how to adapt the tools and parameters for shaping the bottom of the beverage can according to the present invention.

The metal used for the manufacture of beverage cans can be any aluminum alloy known to those skilled in the art which is suitable for this application. For example, an AA3104 type alloy can be used. The metallurgical state of the aluminum alloy can be adapted according to the particular application. For example, the metallurgical state can be H14, H16 or H19, as described in standard EN515 (June 1993).

EXAMPLES

For the purpose of illustrating the present invention, several beverage can preforms have been evaluated from the point of view of their overturning pressure and their increase in can height as a function of internal pressure. The preforms correspond to the beverage can just after the initial bottom shaping, without taking into account the subsequent recovery steps (reforming in English) of the dome. The metal of the beverage cans was AA3104 aluminum alloy in H19 metallurgical condition.

To determine the turning pressure, follow the height of the beverage can, measured between the base of the lower ring and the top of the beverage can as a function of the internal pressure. These measurements make it possible to draw a curve such as that presented in Figure 12. In this figure, the reference C1 corresponds to a reference beverage can having a conventional geometry as illustrated in Figure 1 and a dome sheet thickness of 240. pm. The reference C2 corresponds to a reference beverage can having a conventional geometry as illustrated in Figure 1 but with a dome sheet thickness of 220 µm. The bearing diameter of C1 and C2 is 57 mm. The reference C3 corresponds to the drink can C2 but with a support diameter of 43 mm, a height H1 of 9.35 mm so as to avoid breaking in the rectilinear part 2 of the dome during shaping, and a height H2 of 10.5 mm such that the angle Al is kept identical to that of Cl. The reference C4 corresponds to the drink can C3 but with a width L4 of the lower ring of 3.7 mm. The references C1 to C4 are not according to the present invention. The drink can C5 is according to the present invention and correspond to the drink can C4 but with N = 18 concave deformations (ribs) distributed along the lower ring and a lower ring comprising a flat.

Table 1 below gives the different characteristics of the C5 drink can.

[Table 1]

The evaluation of the overturning pressure and of the increase in the height of the box as a function of the internal pressure was carried out thanks to a numerical modeling by finite elements with the commercial software "LS-Dyna", version 10.1, developed by the Livermore Software Technology Corporation. The modeling consisted in first drawing the three-dimensional shape of the different drink can bottoms in Computer Aided Design. The three-dimensional geometries have been discretized according to a sufficiently fine finite element mesh so that one can precisely simulate its mechanical behavior. The boundary conditions were applied to simulate the behavior of the preform as a whole during the internal pressure resistance and axial force resistance tests.

Regarding the resistance test to internal pressure, the calculation was controlled with a constant gas flow increment, allowing to simulate:

the resulting internal pressure, and

- the displacement of the various points of the bottom under this internal pressure.

By combining these two variables, it was possible to draw the curves, for each of the cans tested, giving the increase in the height of the beverage can as a function of the internal pressure, normalized respectively by the pressure and the height of the can. drink during the inversion of the reference C1. FIG. 12 corresponds to a monotonic increase in the internal pressure, until the dome is inverted. Concerning the resistance test to the axial force, the calculation was controlled with an increment of vertical displacement of the upper end of the box body, making it possible to simulate: the resulting axial force, and

the displacement of the various points of the bottom under this axial force.

By combining these two variables, it was possible to plot the curves, for each of the cans tested, giving the resulting axial force on the upper end of the beverage can as a function of the applied displacement, normalized respectively by the force and the

displacement during the inflection of the curve of the reference Cl. FIG. 13 corresponds to a monotonic increase in the displacement, until the inflection of the curve then the bottom sag at maximum force.

The results obtained in terms of the beverage can inverting pressure and the inflection of the curve of the axial force as a function of the axial displacement, characterizing the resistance to the axial force of the beverage can bottom, are given in Figures 12 and 13 and in Table 2 below.

[Table 2]

According to the curves of Figures 12 and 13 and Table 2 above, the beverage can according to the present invention makes it possible to counterbalance the negative effects of a reduction in thickness of the initial sheet and therefore of the sheet of the dome ( drink can C2) on the overturning pressure and the axial resistance of the drink can, and to find a good compromise compared to the values obtained with the reference drink can C1, namely of the same order of magnitude for the resistance to pressure internal and more than 85% of the axial resistance.

It should be noted that Figures 12 and 13 illustrate the synergistic effect of the combination between the decrease in the diameter of the lower ring, the widening of the lower ring and the presence of concave deformations in the lower ring. Indeed, a satisfactory compromise between overturning pressure and resistance to axial force can only be obtained by combining the three characteristics together. The combination of only two elements between them is not enough (see curves C4).

Claims

1. Beverage tin made of aluminum alloy, preferably for carbonated beverage, comprising:

- a body 6 of cylindrical shape having an external diameter DI;

a convex lower ring 7 having a bearing diameter D2 and a flat of width L2;

- an outer shoulder 5 of radius RI;

- a comb 4 connecting the outer shoulder 5 and the lower ring 7;

2. Beverage can according to claim 1, characterized in that the external diameter DI of the body 6 of the beverage can is 50 to 75 mm, preferably 55 to 70 mm.

3. Beverage box according to any one of the preceding claims, characterized in that the dome 1 has at least one of the following characteristics:

- A diameter D2 of the lower ring 3 of 39 to 47 mm, preferably 40 to 46 mm;

- a depth H1 of 7 to 12 mm, preferably 8 to 11 mm; and or

4. Beverage can according to any one of the preceding claims, characterized in that the lower ring 7 has at least one of the following characteristics:

- a width L4 of 3 to 4.5 mm, preferably 3.3 to 4 mm;

- A flat forming an angle A2 with the horizontal in the direction of the axis of symmetry of the beverage can from 0 to 10 °; and or

- a flat having a length L2 of 0 to 2 mm. 5. Beverage can according to any one of the preceding claims, characterized in that the comb 4 has at least one of the following characteristics:

- a height H2 of 5 to 20 mm, preferably 6 to 14 mm;

- A rectilinear section forming an angle Al with the horizontal of 30 to 40 °;

- a diameter D4 of the beginning of the rectilinear section of 42 to 53 mm;

a height H4 of the start of the rectilinear section of 1.5 to 4 mm, preferably 1.5 to 3.5 mm; and or

- a length L1 of the rectilinear section from 0 to 13,

5 mm.

6. Beverage can according to any one of the preceding claims, characterized in that the connecting portion between the comb 4 and the lower ring 7 comprises at least one of:

- a radius R2 of 2 to 4 mm; and or

- a radius R3 of 1 to 3 mm.

7. Beverage can according to any one of the preceding claims, characterized in that the connecting portion between the lower ring 7 and the rectilinear part 2 of the dome 1 comprises a radius R4 of 1 to 3 mm.

8. Beverage can according to any one of the preceding claims, characterized in that the concave deformations 8 have at least one of the following characteristics:

- a length L5 of 1 to 10 mm, preferably 1 to 5 mm;

- a number N from 4 to 36, preferably from 6 to 24;

a width L3 of 2 to 4.5 mm, preferably 2.5 to 3.5 mm;

- a radius R5 of 2 to 4 mm;

- a radius R6 of 1 to 3 mm;

- a length L5 of 1 to 10 mm;

- a radius R7 of 0.5 to 4 mm; and or

- a radius R8 of 0.5 to 20 mm.

9. A method of manufacturing a beverage can according to any one of the preceding claims, comprising the following successive steps: - Supply of an aluminum alloy, for example AA3104, for example in the metallurgical state H14 or H19, in the form of a strip with a thickness of 180 to 230 μm, preferably 190 to 220 μm;

- cutting of discs called blanks in the aluminum alloy strip;

- Stamping and stretching of the blanks to obtain a beverage can body, using tools suitable for forming the beverage can as described in any one of the preceding claims;

- Manufacture of a cover with another aluminum alloy, for example AA5182;

- assembly of the lid and the body of the drink can to obtain a drink can.

10. Tool for shaping the beverage can according to any one of claims 1 to 8.