FR2710611A1 - Outer cap with thinned skirt and manufacturing method - Google Patents

Abstract

The cap (1) made of aluminium or aluminium alloy, intended to be crimped over the neck (4) of a bottle whose collar (5) comprises a lower crimping shoulder (7), comprises a head (2) and a truncated cone-shaped skirt (3), characterised in that, in order to allow satisfactory capping and subsequent opening with a knife, on the one hand, the said skirt (3) comprises a succession of at least two truncated cone-shaped walls of increasing thickness and, on the other hand, the aluminium or alloy of the said cap is in the annealed state, its micro-hardness being between 25 and 35 Hv, and the number of grains in the thickness of the skirt being between 2 and 7. The method comprises the intermediate manufacture of a blank with stepped cylindrical walls of different thicknesses.

Description

THINNING SKIRT CAPPING CAPSULES AND METHOD FOR
MANUFACTURING
FIELD OF THE INVENTION
The invention relates to the field of capsules for overcapping containers, typically of wine bottles, the neck of which is closed by a cork stopper which constitutes the means for capping said container.

Overcapping capsules provide several functions - protection of said capping means, - guarantee of the integrity of the contents of the container, the skirt of the overcapping capsule being crimped under the ring of the neck of the container and thereby constituting a means of ensure the inviolability of the container, - support of a decoration intended to enhance the container and its content and contributing to the identification of a content, a brand etc ...

- possible support of a tax mark (on the head of the capsule).

PRIOR ART
Numerous variants of metal overcapping capsules are known, most often based on tin, aluminum, and less and less based on tin plated lead for well known reasons related to the toxicity of lead.

These capsules may or may not be provided with means intended to facilitate their opening, these means varying according to the mode of opening.

When it is desired that the opening of the capsule (or uncapping) can be carried out by hand, it is provided with a tearing tab, as illustrated for example in French patent FR-B1- 2,670,184 in the name of the plaintiff.

In case the opening of the capsule is made with a knife by incision above the ring, it is convenient to use a capsule provided with a peripheral rib which will allow the guiding of the knife blade, as described in the French patent FR-B1- 2,636,047 in the name of CEBAL, the patronymic's previous surname.

PROBLEM
There are many ways, more or less academic and recommended, to uncap a bottle whose neck is coated with an overcap not provided with easy opening means (tear-off tab by hand for example): decapping is carried out using a knife blade by incising the skirt circularly to release the upper part of the capsule and separate it from the lower part of the capsule which will remain integral with the neck of the container.

In practice, the consumer can make the incision at different levels of the capsule: at the head / skirt junction, on the upper part of the skirt above the ring, at the upper shoulder of the ring, at the level of the ring itself or under the ring.

However, the sommeliers method, which is the one used in large restaurants where high quality wines are consumed, first includes an incision of the skirt of the overcap capsule under the ring (using a knife), then tearing off the upper part of the capsule skirt.

 It is therefore important that this type of decapping be easy and non-injurious, otherwise the marketing of wines, which are otherwise reputed, may be adversely affected.

In its concern to obtain overcapping capsules having both an improved ease of opening for sommeliers and a low cost price, the applicant had the idea of manufacturing capsules with a skirt of small relative thickness, a small thickness of metal which must ensure both a saving of metal and, a priori, great ease of uncapping.

However, it encountered the following problem: the crimping, under standard conditions, of overcap capsules with thin skirt led to a defective result, in particular by the appearance of folds under the ring (shrinkage zone of the skirt during crimping). These folds are unacceptable as they damage the aesthetics of the bottle, and therefore the brand image of a product, which can also be prestigious.

Ultimately, either the capsules thus obtained did not have crimping defects, but were difficult to open, or the capsules were easy to open but then they presented crimping problems and apparent defects (folds under the ring, etc. .).

The Applicant has therefore sought a solution to this problem to, at the same time, obtain an economical capsule, easy to open including for sommeliers, and free of folds under ring after crimping.

OBJECTS OF THE INVENTION
A first object of the invention consists of aluminum capsules which respond to the problem posed.

A second object of the invention is a method of manufacturing metallic or metal-based capsules which meet the requirements defined by the problem posed.

DESCRIPTION OF THE INVENTION
According to the first object of the invention, the aluminum or aluminum alloy overcap capsule, intended to be crimped onto the neck of a bottle, the ring of which comprises a lower crimping shoulder and possibly an upper shoulder, comprises a head and a frustoconical skirt, and is characterized in that, so as to allow satisfactory implementation (crimping during capping) and easy and non-injurious knife opening, a) said skirt comprises a succession of at least two frustoconical walls of increasing thickness (the wall having the smallest thickness being the closest to said head), and b) the aluminum or aluminum alloy of said capsule is in the annealed state, its microhardness being included between 25 and 35 Hv, and the microstructure of its skirt wall being characterized by the presence of a number of grains, in the thickness of the J skirts between 2 and 10.

Following this research, the plaintiff arrived at the solution of the problem posed using 2 essential means defined under a) and b) and used jointly.

Indeed, if the capsule does not jointly present the two characteristics a) and b), characteristic a) being of geometrical order and characteristic b) of metallurgical order, the capsule does not respond to the problem posed.

A particularly surprising element of this invention resides in the fact that, in spite of an annealed state and a localized thinning of the skirt of the capsule, the latter behaves during the capping, where it is very stressed on the plane mechanical, like a capsule of greater thickness, that is to say without harmful deformation of the skirt (twisting for example). Surprisingly, the capsule according to the invention, although locally of reduced thickness, behaves, during its manufacture and during capping, like a mechanically stronger capsule of the prior art.

DESCRIPTION OF THE FIGURES
Figure 1 shows a capsule (1) overcap, in axial section along the axis (8) of the capsule, covering the neck (4) of a bottle closed by a stopper (12). The neck (4) comprises a glass ring (5) with upper shoulder (6) and lower shoulder (7).

This figure, which represents generic elements of an overcapped bottle, corresponds to both the prior art and the invention.

Figures 2a and 2b show, in axial section along the axis (8) of the capsule, capsules according to two methods of the invention, the thicknesses of the skirt and head having been greatly exaggerated with respect to the height and the diameter of the capsule to illustrate the geometric characteristics of the capsules according to the invention.

FIG. 2a illustrates the case where the skirt (3) of the capsule (1), skirt designated by T2, is formed by a succession of 2 frustoconical walls T21 and T22, of increasing thickness e21 and e22 respectively.

The connection of the head (2) and the skirt (3) is made by a centering shoulder (9). The capsule (1) comprises a rod (10) intended to facilitate the unstacking of the capsules nested one inside the other to form capsules sticks.

FIG. 2a shows a portion of neck (4) to indicate diagrammatically, after crimping, the position of thinned wall T21 with respect to the ring (5) and to its lower shoulder (7). On the axis (8), we have carried an axis of ordinate h as well as the height H of the capsule (1).

FIG. 2b illustrates the case where the skirt (3), designated by
T3, is formed by a succession of 3 frustoconical walls
T31, T32 and T33, respectively of increasing thickness e31, e32, and e33. As in the case of FIG. 2a, the connection of the head (2) and the skirt (3) is made by a centering shoulder (9) and the capsule (1) comprises a rod (10).

FIGS. 3a to 3h illustrate a typical manufacturing of a capsule blank (= capsule formed, before heat treatment and decoration) according to the invention corresponding to example 1
FIG. 3a represents the strip (14) of aluminum alloy in which circular flanks (13) are cut.

FIG. 3b represents the cylindrical blank (15) obtained by stamping a sidewall (13) and calibration.

FIG. 3c represents the cylindrical stepped blank E1 with 3 stages obtained, using a punch and two rings, during the first stage pass, in which the 3 cylindrical stages E1l, E12 and E13 are of thickness close to slightly less than the thickness eO of the starting strip.

FIG. 3d represents the cylindrical stepped blank E2 with 4 stages obtained, using a punch and a drawing ring, during the second stretching / drawing pass, in which the first stage E24 is thinned to 60-70 µm, the next 3 stages E22, E23 and E24 retaining a thickness of 95-105 µm.

FIG. 3e represents the staged cylindrical blank E2 with 5 stages obtained, using a punch and a ring, during the third stage pass, the thinned stages being the stages E31 and E32 with their thickness between 60 and 70 μm, and the stages E33 to E35 retaining their thickness of 95-105 μm.

In FIG. 3f, during the fourth stepping pass, a cylindrical stepped blank E4 with centering shoulder (9) is formed using a punch and a ring, the stages E41, E42 and E43 being thinned (thickness between 60 and 70 μm), the stages E44 to E46 having a thickness of 95-105 μm.

FIG. 3g represents the blank of capsule with a frustoconical skirt T2 obtained by pressing the blank E4 between punch and frustoconical matrix.

FIG. 3h represents the blank of capsule with frustoconical skirt T2 after cutting to length.

The following stages in the manufacture of the capsule (heat treatment, decoration, etc.) have not been shown.

FIG. 4a represents, in partial section along the axis (8), the manufacture of the blank E2 in Example 2 using a stepped punch (16) comprising a clearance (18), and a ring (17). FIG. 4b is the enlargement of the circled portion A of FIG. 4a and shows the depth of the clearance ss e - of the order of 20 μm.

DETAILED DESCRIPTION OF THE INVENTION
The skirt (3) of the capsule (1) according to the invention comprises a succession of at least two frustoconical walls of increasing thickness, preferably little or not visible externally, which is obtained thanks to a succession of frustoconical walls d increasing thickness having a thickness profile in the form of stair treads on the internal surface of said skirt (3).

According to a first embodiment of the invention, said succession comprises two frustoconical walls denoted T21 and T22 of increasing thickness denoted respectively e21 e22 with e21 <e22, T21 being the area closest to said head (2) and T22 the most distant . T2 was noted the frustoconical skirt with two frustoconical walls. See figure 2a.

Preferably, e21 is between 40 and 80 μm, e22 is between 60 and 110 μm, and eO is between 80 and 130, μm, if the thickness of said capsule head is designated by eg (= thickness of the band or starting format).

The heights of the walls T21 and T22 are chosen as a function of the type of neck (4) to be overcapped, so that, after crimping the overcap (1) on the neck (4), the thinnest wall T21 is pressed against said lower shoulder (7) and over a portion of at least 3 mm under said lower shoulder (7), as suggested in FIG. 2a.

Typically, the height of the wall T21 is between 10 and 20 mm, the height of the wall T22 being equal to the total height H of the capsule reduced by the height of the wall T21 (to the thickness of the head) .

According to a second embodiment of the invention, represented in FIG. 2b, said succession comprises three frustoconical walls denoted T31, T32 and T33, of increasing thickness denoted respectively e31, e32 and e33, with e31 c e32 <e33, T31 being the zone closest to said head (2) and T33 the most distant. T3 has been denoted the frustoconical skirt with three frustoconical walls.

Preferably, e31 is between 40 and 80 µm, e32 is between 50 and 85 µm, and e33 is between 60 and 110 µm, eo being between 80 and 130 µm.

The heights of the walls T31 and T32 are chosen as a function of the type of neck (4) to be overcapped, so that, after crimping the overcap (1) on the neck (4), the thinnest wall T31 is pressed against said upper shoulder (6) and part of said shoulder (5), and the wall T32, of intermediate thickness, is pressed against said lower shoulder (7) and on a part of at least 3 mm under said shoulder (7).

These two methods of the invention are not limitative of the invention. They simply illustrate the inventive concept of the applicant, with regard to the geometric aspect.

According to this concept, the thickness of the skirt of the capsule varies according to the height h (= ordered in FIG. 2a) and more precisely according to the relative position of each portion of frustoconical skirt relative to the ring (5) of the neck. (4) to be overcapped. This thickness takes into account all the constraints - different depending on the height h - to which the capsules are subjected, whether it be constraints of mechanical strength during encapsulation, or whether it is constraints of ease of opening during uncapping, the large difficulty, overcome by the invention, residing in the fact that these constraints, capping and uncapping, are generally contradictory.

In some cases, it could be advantageous to produce a succession of more than three frustoconical walls, but the objectives of the invention are generally achieved with a succession of two or three frustoconical walls (skirts T2 or T3).

In general, whatever the method chosen of the invention and the number of frustoconical walls, the total height H of the capsule is between 20 and 70 mm, its diameter at mid-height is between 20 and 40 mm and its taper is between 1/10 and 1/30.

Preferably, the walls T21 or T31 (thinner walls of the skirts T2 or T3) comprise a centering shoulder (9) or are connected to said head (2) by a centering shoulder (9).

This shoulder (9), typically between 3 and 6 mm high, is connected to said head (2) with a radius of curvature between 1.5 and 4 mm, and is connected to the wall T21 or
T31 with a radius of curvature between 0.8 and 4 mm.

 I1 is advantageous to provide the skirt part furthest from said head (walls T22 or T33 of skirts T2 or T3) with a rod (10) located at a distance from the end of the skirt (3) (opposite end at said head) between 5 and 15 mm, so as to facilitate supply to the unit, when crimping said capsule (1) on the neck (4), capsules stored in a stick and to avoid deformation of the skirt for capping line distribution.

Similarly, it is advantageous for the end of said skirt (3) to be flared so as to adapt to the curvature of said rod (10) when the capsules (1) are stacked to form sticks.

With regard to the choice of the material constituting the aluminum alloy capsule, this alloy must preferably have an Al content greater than 98 t by weight and contain less than 1% by weight of the sum of the elements Si and Fe, the total content by weight of elements other than Si and Fe being less than 1% (sum of toxic heavy metals Pb, CrVI, Cd <100 ppm - standard NF A 50541), and its mechanical characteristics are preferably as follows : Rm between 65 and 95 MPa, Ru0.2 between 20 and 55 MPa, and its elongation A% greater than 15%.

A second object of the invention is a method of manufacturing metal capsules.

This method of manufacturing an overcap capsule (1) comprising a head (2) and a skirt (3), intended to be crimped onto the neck (4) of a bottle whose ring (5) comprises a lower shoulder (7) crimping and optionally an upper shoulder (6), includes the transformation into a capsule, by stamping, drawing and calibration, of a blank blank (13) cut from a strip (14), or a format, of material to metallic base, and the decoration of the capsule, and is characterized in that, a) supplying said strip (14) or said format in material, comprising a metallic layer, chosen from the group formed by aluminum or alloy of aluminum in the annealed state, a tin alloy, a metalloplastic complex comprising at least one layer of aluminum and one thermoplastic layer (polyolefin for example), b) after cutting a blank blank (13) in said strip ( 14) or said format, one forms, by stamping-stretching of said blank (13), a cylindrical blank (15) of H / D ratio (height / diameter) of between 0.5 and 3.5.

c) the skirt of the cylindrical blank (15) is stretched in p drawing passes (using drawing rings and stepped punches) or of calibration, so as to form a blank Ep (Ep denoting l blank obtained on the p-th pass and last stretch of drawing or calibration) with locally thinned stepped skirt comprising n cylindrical stages (successive stages, of increasing outside diameter, designated by Epl, ...... Epn1 the stage Epl being the closest to the head of the capsule), blank Ep in which at least the first stage Epl has a reduced skirt thickness compared to the skirt thickness of the last stage Epn, d) it is compressed between punch and frustoconical matrix the blank with a stepped skirt Ep obtained in c), so as to form a blank with a substantially frustoconical skirt, with a smooth external surface and an internal surface whose thickness profile is in the form of stair treads (skirt formed by '' a succession of at least two tron walls conical of different thickness and designated by Ti where i indicates the number of frustoconical walls of different thicknesses, the successive frustoconical walls, of increasing thickness, being designated by Til, Ti2,. . .Tii).

e) the blank with a frustoconical skirt Ti, obtained in d), is heat treated for a time and at a temperature chosen so as to remove the lubricant (introduced in at least one of steps a), b), c)) present on the surface of the capsule obtained in d) and in obtaining a capsule (1) with said metallic layer in the annealed state.

This general process makes it possible to obtain a wide variety of capsules which respond to the problem posed.

However, in step c) the value of p is preferably between 2 and 7, the value of n is preferably between 2 and 8, and in step d) the value of i is preferably 2 or 3.

In the case where the starting material is an aluminum alloy, in a strip or format with a thickness of between 80 and 130 μm, in step d) of the process, and for i = 2, the blank is obtained. frustoconical skirt T2, which has a frustoconical wall T21 of thickness between 40 and 80 μm over a height suitable for the neck to be encapsulated, so that the thinnest frustoconical wall T21 covers, after crimping, said lower shoulder (7 ) and a portion of at least 3 mm under said lower shoulder (7), the frustoconical wall T22 having a thickness of between 60 and 110 μm.

Similarly, for i = 3, the blank with a frustoconical skirt T3 has a frustoconical wall T31 of thickness between 40 and 80 μm over a height suitable for the neck to be encapsulated, so that the thinnest frustoconical wall T31 covers, after crimping, said upper shoulder (6) and part of the shoulder (5), the tapered median wall T32 being between 50 and 85 μm thick over a height suitable for the neck to be encapsulated, so that that the median frustoconical wall T32 covers, after crimping, said lower shoulder (7) and a portion of at least 3 mm under said shoulder (7), the wall T33 having a thickness of between 60 and 110 μm.

 I1 is advantageous to provide the capsule with a centering means which facilitates the capping. For this, at the end of step c) of the method, a centering shoulder (9) is formed on the height of between 3 and 6 mm on the part of the stage Ep1 connected to said head (2). .

Similarly, to facilitate unstacking of the stick capsules, at the end of step d) of the method, a circular rod (10) is formed on the frustoconical wall Tii (i = 2 or 3) - the thickest - of the tapered skirt Ti, at a distance of between 5 and 15 mm from the end of the skirt, so as to avoid the packing of the capsules stored in sticks.

The method of the invention applies to all of the materials in a stampable and stretchable strip, essentially metallic, that is to say comprising, by volume, more than 50% of metal, materials which can be used for the manufacture of overcapping capsules. such as tin alloys, aluminum alloys, multi-layer metalloplastic materials of the M / P, M / P / M type where M and P respectively denote hde metal or plastic layers adhering to each other, possibly to the using an adhesive layer.

However, preferably, an aluminum alloy is supplied as material. This alloy is chosen from those of the 1000 series, 8011, 3003 (according to aluminum nomenclature
Association) in strip or formats of thickness eO between 80 and 130 pm, and having a value of Rm between 60 and 110 MPa, a value of Ru0.2 between 20 and 60
MPa and an elongation A% greater than 12%.

 It is convenient according to the invention to preferably supply said aluminum alloy in strip or pre-lubricated formats with a lubricant chosen to allow the capsules to be shaped by stamping and drawing, to be eliminated during the thermal treatment of the capsules, and so as not to clog the tools or stain the capsules.

According to the invention, in step e) of the process, it is advantageous to carry out said heat treatment by scrolling in an induction heating device the frustoconical capsules obtained in d), with a residence time of between 5 and 20 seconds for sufficient installed power so that the capsule temperature is between 300 and 600 "C.

Preferably, the duration and the temperature of the heat treatment are chosen so as to obtain a metallic layer of grain Al alloy according to the thickness in optimum number (between 2 and 10), grains of average size typically between 5 and 30 µm, metallic layer whose grain boundaries no longer contain intermetallic precipitates.

Indeed, if the grain is too fine, the capsule will be more difficult to cut with a knife. On the other hand, if the grain is coarse, the capsule will have a coarse surface appearance called "orange peel".

The heat treatment of the invention allows a very high rate of temperature rise of the frustoconical blank (typically 450 "C in 5 s), which has been found advantageous to control the recrystallization of the work hardened blank and to obtain faithfully reproducible the desired texture (number and dimensions of grains) and simultaneously obtain the elimination of dislocations in the metal, as well as the dissolution of the grain boundaries, which is necessary to ensure the homogeneity and ductility of the metal and therefore to obtain good behavior of the metal when crimping (flow of the metal under the pressure of the crimping rollers without creases and without tearing of the metal).

The heat treatment must of course be adapted to the nature of the material chosen and it must not degrade the plastic material significantly in the case where the material is a multilayer material M / P or M / P / M.

EXAMPLES OF REALIZATION
EXAMPLE 1
Capsules with a frustoconical skirt (type T2) of two different thicknesses were made (e21 <e22). For this a) We supplied a lubricated strip of aluminum (14) in 1100 alloy (according to designation Aluminum Association) 110 µm +/- 7 µm thick and 95 mm wide (supplier of the lubricated strip for overcapping capsules: Company
RHENALU)
The characteristics of this metal are as follows
RM: 75 MPa RP0,2: 40 MPa
Elongation: 18% b) To manufacture an overcap capsule according to the invention, a cylindrical blank (15) was first formed as follows * blanks (13) of 93 mm blanks were cut from the strip (14) in diameter, * then first cylindrical capsule blanks (15) were formed by stamping-stretching of blanks (13), as shown diagrammatically in FIG. 3b.

This blank (15) has a height of 53 mm and an outside diameter of 32.2 mm,
Stamping is carried out in a manner known per se by deformation of the lubricated metal strip between a punch and a die in 2 stamping passes.

After 2 stamping passes, each stamped blank was stretched in a manner known per se, by punch and drawing ring. See Figures 3a and 3b.

c) Each cylindrical stamped-drawn blank (15) was then transformed into a blank with a stepped skirt (see FIGS. 3c to 3f) in four stretching or staging passes * we formed, using a first stepped punch and two rings, the blank E1 at the first pass (stepping) with a stepped skirt with 3 cylindrical stages E11 / E12 / E13, each of thickness between 95 and 105 μm. See figure 3c.

* we formed, using a second stepped punch and a ring, the blank E2 on the second pass (stepping + stretching) with a stepped skirt with 4 cylindrical stages E21 / E22 /
E23 / E241 the stage E21 having a thickness between 60 and 70 μm and the other stages having a thickness between 95 and 105 μm. See figure 3d.

* we formed, using a third stepped punch and a ring, the blank E3 on the third pass (staggering + stretching), with a stepped skirt with 5 cylindrical stages E31 /
E32 / E33 / E34 / E35, the stages E31 and E32 having a thickness between 60 and 70 µm, the other stages having a thickness between 95 and 105 µm. See figure 3e.

* finally, using a fourth stepped punch and a ring, the blank E4 was formed on the fourth pass (calibration of the head (2) of the blank E3 and formation of a shoulder of centering (9) of thickness between 70 and 80, um), with a stepped skirt with 6 stages (E41 to E46). See figure 3f.

A blank E4 was obtained, with an internal diameter staggered between 28 mm and 32.2 mm, and 56 mm in height, the height of the thinned stages (E41 to E43) being 19 mm and that of the unthinned stages (E44 to E46) being 31 mm.

d) Then, using a punch and a frustoconical matrix having the conicity of the capsule (1) to be obtained (i.e. 1/25), the E4 blanks with stepped skirt into blanks with frustoconical skirt T2. See Figures 2a and 3g.

By trimming the open end of the frustoconical zone (8) of the skirt at the desired height, blanks with frustoconical skirt T2 of the following dimensions were obtained * height: 50 mm * height of the thinned skirt part: 17 mm * maximum inside diameter: 31.5 mm (bottom of skirt) * minimum inside diameter: 28 mm (top of skirt).

with a thinned T21 stage 19 mm high and 60-70 µm thick and a T22 stage 31 mm high and 95-105 µm thick.

e) The blanks with a frustoconical skirt T2 obtained in d) were then heat treated in an induction furnace of 12
KW of installed power, scrolling with a passage time of 8 seconds, the temperature of the capsules rising to approximately <RTI ID = 17.

The details of the manufacturing of the frustoconical skirt blank
T3 will not be repeated here, because what distinguishes this example from the previous one relates above all to the stepped punch making it possible to obtain the stage E21 of the blank E2 (see figures 3d, 4a and 4b): this punch (16) includes a clearance (18) for a dimension (h) of between 11 and 19 mm, so as to obtain an E21 stage whose thickness over the first 11 mm is between 60 and 70 mm and whose thickness, over the 8 mm following is between 80 and 90 mm.

The Applicant was very surprised to find that, despite this clearance, the separation (or stripping) of the blank
E2 and the stepped punch (16) posed no problem.

The frustoconical skirt T3 of the final blank obtained has the following geometric characteristics * stage T31: height = 11 mm
thickness = 60 -70 um * T32 stage: height = 8 mm
thickness = 80-90 pm * stage T33: height = 31 mm
thickness = 95-105, um
With the capsule of Example 2, we found a hardness and a number of grains comparable to the values of Example 1.

EXAMPLE 3
This example, and those which follow, are comparative examples outside the invention.

 I1 differs from Examples 1 and 2 in that the skirt of the capsule is of substantially uniform thickness and between 100 and 110 μm.

The hardness and number of grains values are close to those obtained in Examples 1 and 2.

EXAMPLE 4 It differs from example 3 in that the skirt of the capsule is of substantially uniform thickness and between 80 and 90 μm. It was noted that there were manufacturing difficulties (high rate of scrap).

The hardness and number of grains values are close to those obtained in Examples 1 and 2.

EXAMPLE 5
It differs from Example 1 in that the duration of the heat treatment has been reduced to 2 seconds.

A hardness of 30 Hv and an average number of grains of 15 were obtained.

EXAMPLE 6 It differs from example 1 in that the duration of the heat treatment has been increased and brought to 45 s.

A hardness of 22 Hv and an average number of grains of 2 were obtained.

RESULTS
The capsules obtained according to all these tests have been examined and tested according to three criteria by persons skilled in the art, and qualified by yes / no in response to the following questions * ASPECT: possible marketing? * CAPSULATION: absence of creases, twists ...? * DECAPSULATING: opening with a "normal" knife?
CAPSULAGE DECAPSULAGE ASPECT
TEST 1 yes yes yes
TEST 2 yes yes yes
TEST 3 yes yes no
TEST 4 yes no yes
TEST 5 yes no no
TEST 6 no yes yes
Conclusions
The invention, by a combination of geometric and metallurgical means, therefore made it possible to find a narrow path between the contradictory requirements of capping on the one hand and decapping with a knife in the manner of sommeliers on the other hand, what the prior art could not do.

ADVANTAGES OF THE INVENTION
Thanks to the invention, the aluminum overcapping capsules can access the noblest outlets of these capsules, namely the overcapping of high quality wines which are served, in particular in large restaurants, and decapsulated by sommeliers according to their method. traditional.

 It should be noted that this accession to prestige uses is only accompanied by limited modifications to the production lines of the prior art, hence an additional production cost, due to the greater number of tools (punches and rings ), relatively reduced, and largely offset by the reduction in thickness of the skirt and the resulting consumption of metal.

Claims (24)

1 - Overcap capsule (1) made of aluminum or aluminum alloy, intended to be crimped onto the neck (4) of a bottle, the ring (5) of which comprises a lower shoulder (7) for crimping and possibly an upper shoulder (6), comprising a head (2) and a frustoconical skirt (3), and characterized in that, so as to allow satisfactory implementation (crimping during capping) and an easy and non-injurious knife opening, d 'firstly, said skirt (3) comprises a succession of at least two frustoconical walls of increasing thickness (the wall having the smallest thickness being the closest to said head), and secondly, l aluminum or alloy of said capsule is in the annealed state, its microhardness being between 25 and 35 Hv, and the microstructure of its skirt wall being characterized by the presence of a number of grains, in the thickness of the skirt, between 2 and 10. 2 - Capsule according to claim 1 wherein said succession of frustoconical walls of increasing thickness has a thickness profile in the form of stair treads on the internal surface of said skirt. 3 - capsule according to claim 2 wherein said succession comprises two frustoconical walls (of a denoted skirt T2) denoted T21 and T22 of increasing thickness denoted respectively e21 e22 with e21 <e22 the wall T21 being the closest to said head (2) and the wall T22 furthest away. 4 - Capsule according to claim 3 wherein, e21 is between 40 and 80 µm, e22 is between 60 and 110 µm, and eg is between 80 and 130, um, if the thickness of said head is designated by eg capsule. 5 - Capsule according to claim 4 wherein the height of the walls T21 and T22 is chosen according to the type of neck (4) to be overcapped, so that, after crimping the overcap (1) on the neck ( 4), the wall The thinnest T21 is pressed against said lower shoulder (7) and over a portion of at least 3 mm under said lower shoulder (7). 6 - capsule according to claim 5 wherein the height of the wall T21 is between 10 and 20 mm, the height of the wall T22 being equal to the total height of the capsule reduced by the height of the wall T21 (at head thickness close). 7 - Capsule according to claim 2 wherein said succession comprises three frustoconical walls (of a skirt denoted T3) denoted T31, T32 and T33, of increasing thickness denoted respectively e31, e32 and e33, with e31 <e32 <e33, T31 being the area closest to said head (2) and T33 the farthest. 8 - Capsule according to claim 7 wherein, e31 is between 40 and 80 pm, e32 is between 50 and 85 pm, and e33 is between 70 and 110, um, eg being between 80 and 130, um, if the thickness of said capsule head (2) is designated by eg. 9 - Capsule according to claim 8 wherein the height of the walls T31 and T32 is chosen according to the type of neck (4) to be overcapped, so that, after crimping the overcap (1) on the neck ( 4), the wall The thinnest T31 is pressed against said upper shoulder (6) and part of said shoulder (5), and the wall T32, of intermediate thickness, is pressed against said lower shoulder (7) and over a portion of at least 3 mm under said shoulder (7). 10 - Capsule according to any one of claims 1 to 9 wherein the total height of the capsule is between 20 and 70 mm, its diameter at mid-height is between 20 and 40 mm and its taper is between 1/10 and 1/30 11 - Capsule according to claim 10 in which the wall T21 or T31 comprises a centering shoulder (9) or is connected to said head (2) by a centering shoulder (9). 12 - Capsule according to claim 11 wherein said shoulder (9), typically between 3 and 6 mm high, is connected to said head (2) with a radius of curvature between 1.5 and 4 mm, and is connected at wall T21 or T31 with a radius of curvature between 0.8 and 4 mm. 13 - Capsule according to any one of claims 10 to 12 in which the skirt part furthest from said head (wall T22 or T33) is provided with a rod (10) located at a distance from the end of the skirt ( 3) (end opposite to said head) between 5 and 15 mm, so as to facilitate supply to the unit, when crimping said capsule (1) on the neck (4), capsules stored in sticks and to avoid deformation of the skirt when dispensing on the capping line. 14 - Capsule according to claim 13 wherein the end of said skirt (3) is flared so as to adapt to the curvature of said rod (10) when stacking the capsules (1) to form sticks. 15 - Capsule according to any one of claims 1 to 14 made of aluminum alloy with, preferably, at least 98% by weight of Al, containing less than 1% by weight of the sum of the elements Si and Fe, the total content by weight of elements other than Si and Fe being less than 1%, having the following mechanical characteristics: Rm between 65 and 95 MPa, Rp between 20 and 55 MPa, A% greater than 15. 16 - Method for manufacturing an overcap capsule (1) comprising a head (2) and a skirt (3), intended to be crimped onto the neck (4) of a bottle whose ring (5) comprises a shoulder lower (7) crimping and optionally an upper shoulder (6), comprising the transformation into a capsule, by stamping, drawing and calibration, of a blank blank (13) cut from a strip (14), or a format, of material based on metal, and the decoration of the capsule, characterized in that, a) supplying said strip (14) or said format in material, comprising a metallic layer, chosen from the group formed by aluminum or aluminum alloy in the annealed state, a tin alloy, a metalloplastic complex comprising at least one layer of aluminum and one thermoplastic layer, b) after cutting a blank blank (13) in said strip or said format, stamping-drawing of said blank (13), a cylindrical blank ( 15) H / D ratio (height / diameter) between 0.5 and 3.5. c) the skirt of the cylindrical blank (15) is stretched in p drawing passes (using drawing rings and stepped punches) or of calibration, so as to form a blank Ep (Ep denoting l blank obtained with the last pass and last stretch of drawing or calibration) with a locally thinned stepped skirt comprising n cylindrical stages (successive stages, of increasing external diameter, designated by Epl, Ep2  .Epn, the stage Epl being the closest to the head of the capsule), blank Ep in which at least the first stage Ep1 has a reduced skirt thickness compared to the skirt thickness of the last stage Epn d) on compresses between the punch and the frustoconical matrix the blank with a stepped skirt Ep obtained in c), so as to form a blank with a substantially frustoconical skirt, with a smooth external surface and an internal surface whose thickness profile has the shape of steps d '' staircase (skirt formed by a succession of at least two frustoconical walls of different thicknesses and designated by Ti where i indicates the number of frustoconical walls of different thicknesses, the successive frustoconical walls, of increasing thickness, being designated by Til, Ti2,. .Tii). e) the blank with a frustoconical skirt Ti, obtained in d), is heat treated for a time and at a temperature chosen so as to remove the lubricant (introduced in at least one of steps a), b), c)) present on the surface of the capsule obtained in d) and in obtaining a capsule (1) with said metallic layer in the annealed state. 17 - Method according to claim 16 wherein, in step c) the value of p is preferably between 2 and 7, the value of n is preferably between 2 and 8, and, in step d) , the value of i is preferably 2 or 3. 18 - The method of claim 17 wherein, when i = 2 and when the starting material is an Al alloy, the blank T2 obtained in step d) has a frustoconical wall T21 of thickness between 40 and 80, μm over a height suitable for the neck to be encapsulated and a wall T22 of thickness between 60 and 110 μm, so that the thinnest frustoconical wall T21 covers, after crimping, said lower shoulder (7) and a part of at least 3 mm under said lower shoulder (7). 19 - The method of claim 17 wherein, when i = 3 and when the starting material is an Al alloy, there is obtained, in step d), a blank T3 whose frustoconical wall T31 has a thickness between 40 and 80 μm over a height suitable for the neck to be encapsulated, so that the thinnest frustoconical wall T31 covers, after crimping, said upper shoulder (6) and part of the shoulder (5), the wall of which frustoconical center T32 has a thickness between 50 and 85 μm over a height suitable for the neck to be encapsulated, and whose frustoconical wall T33 has a thickness between 60 and 110 μm, so that the frustoconical central wall T32 covers, after crimping, said lower shoulder (7) and a portion of at least 3 mm under said shoulder (7). 20 - Method according to any one of claims 16 to 19 wherein, at the end of step c) of the method, there is formed, on the part of the stage Epl connected to said head (2), a centering shoulder ( 9) over a height between 3 and 6 mm. 21 - The method of claim 20 wherein, at the end of step d) of the method, a circular rod (10) is formed on the frustoconical wall Tii (i = 2 or 3), the thickest, of the skirt (3), at a distance of between 5 and 15 mm from the end of the skirt, so as to avoid packing of the capsules stored in sticks. 22 - Process according to any one of claims 16 to 21 in which there is preferably supplied an aluminum alloy chosen from those of the 1000 series, 8011, 3003 (according to the nomenclature of the Aluminum Association) in strips or formats of thickness eO between 80 and 130 pm, and having a value of Rm between 60 and 110 MPa, a value of Ro 2 between 20 and 60 MPa and an elongation At more than 12%. 23 - The method of claim 22 wherein preferably supplies said aluminum alloy in strip or pre-lubricated formats with a lubricant chosen to allow the shaping of the capsules by stamping and stretching, to be removed during the heat treatment of the capsules , and so as not to clog the tools or stain the capsules. 24 - A method according to any one of claims 22 to 23 wherein, in step e) of the method, said heat treatment is carried out by scrolling in a induction heating device the frustoconical capsules obtained in d), with a time of stay between 5 and 20 seconds for a sufficient installed power so that the temperature of the capsule is between 300 and 600 "C. 25 - Process according to claim 24 in which the duration and the temperature of the heat treatment are chosen so as to obtain a metallic layer of Al alloy with microstructure chosen with a number of grains in the thickness of the skirt, between 2 and 10, and with grain boundaries no longer contain intermetallic precipitates.