LINER, that is to say: the inner casing of a composite tank for high-pressure gas.

Abstract

The present invention relates to thin-walled metallic liners for composite tanks, type III, preferably designed to contain gases or hydrogen under high pressure, intended for land, sea, air, and space transport, as well as static storage. This liner (5D) consists of a main cylinder of revolution (5) (5'), terminated, at least at one of its ends, by an evolving, substantially hemispherical shape (5c), gradually connecting at its pole to a cylindrical portion (5b) of smaller diameter than the main cylinder (5). The second end of the main cylinder can be either substantially identical to the first (symmetrical configuration) or "blind," that is, it has an evolving shape, substantially in the form of a complete hemisphere, i.e., without a cylindrical portion of smaller diameter than the main cylinder at its pole (asymmetrical configuration). Fig. 10

Description

Title of the invention: LINER, i.e.: inner casing of a COMPOSITE TANK for HIGH-PRESSURE GAS. Field of the art:

[0001] A liner is the inner casing of a high-pressure gas tank, particularly for hydrogen. This tank is intended for land, sea, air and space transport, as well as static storage.

[0002] The present invention relates to liners (5) for high-performance composite tanks having, for the same volume, substantially the internal shape of a conventional liner, that is to say, a main cylinder of revolution (5), terminated, at least at one of its ends, by an evolving, substantially hemispherical shape (5c), progressively connecting at its pole to a cylindrical portion (5b') of smaller diameter than the main cylinder. See [Fig. 10].

[0003] The second end of the main cylinder (5'b') can be substantially identical to the first, (symmetrical configuration); or said to be "blind", that is to say that it has an evolving shape, substantially in the whole hemisphere, that is to say without a cylindrical part of smaller diameter than the main cylinder, at its pole, (asymmetrical configuration). Prior state of the art:

[0004] There are four main types of compressed gas storage tanks:

[0005] - Type I corresponds to a thick metallic casing acting as both structural and liner component,

[0006] - Type II comprises a metallic liner whose cylindrical part is reinforced by a composite (fiber + resin) wound circumferentially by winding. With this type of tank, the liner supports a large part of the load due to pressurization, so it is structural.

[0007] - Type III is a liner entirely wound with resin-coated fiber (composite structure). The liner is metallic; it does not bear the load (or very little) and is only there to prevent hydrogen permeation. This type of liner allows access to high static pressures, for example, 700 bar operating pressure.

[0008] - Type IV is a liner entirely wound with resin-coated fiber (composite structure). The liner is made of polymer, for example high-density polyethylene (HDPE); it does not bear the load and is only there to prevent hydrogen permeation. It should be noted that permeation is still a barrier to the large-scale use of this type of tank, as are the slow (10 minutes) and difficult production time of the liner. This type of liner allows access to high operating pressures (700 bar). The composite structure is generally carbon fiber coated with epoxy resin.

[0009] Type III & IV tanks almost exclusively use their composite structure to ensure good mechanical resistance to pressure.

[0010] Conventional Type III tanks use metal liners with wall thicknesses between 10 and 15 mm. The complexity and extreme slowness of the manufacturing process for such a liner are considerable. It takes approximately half an hour to manufacture! Furthermore, this liner is primarily made of an A6061 grade aluminum alloy. Such an alloy has very low elongation at break, which is a disadvantage for fatigue resistance! Problem analysis:

[0011] As an example, it should be noted that the permeability to hydrogen at 25C: • High-density polyethylene (HDPE) has a density of 2 x 10¹³ (moleH₂.m⁻¹.s⁻¹.MPa⁻¹ / ²) • The strength of aluminum is 6x10¹⁶ (moleH₂.m₁.s₁.MPa₁ / ²)

[0012] We therefore observe, at the same thickness, that there is a difference in permeability of 333 times between that of aluminium and that of HDPE!

[0013] Table 1 gives the typical thickness of an HDPE liner intended for a type IV tank, namely 7 mm. Such a thickness, for an internal capacity of 62 liters, results in a mass approximately equal to 5.66 kg, or 12% of the total mass of said tank, which is far from negligible!

[0014] Furthermore, since the liner is not structural, for a liner with an internal diameter of 372 mm, the composite structure will have an internal diameter of 386 mm and will therefore have to withstand a stress 3.8% greater than that which it would have to withstand for a diameter of 372 mm. The composite structure must therefore be made thicker, resulting in greater mass and higher cost. Brief description of the figures and landmarks:

[0015] [Fig. 1] table giving, for identical internal volume, the liner mass gains induced by the type of liner chosen.

[0016] [Fig.2] graph showing the permeation properties as a function of temperature for 6 candidate metals.

[0017] [Fig. 3] Schematic presentation of the reverse spinning in 3 steps, namely: step [A] placement of the blank (3); then step [B] reverse spinning; and finally step [C] release of the workpiece

[0018] [Fig.4] Schematic cross-sectional view of an aluminum blank (3) and what it will become in fine lines (5)

[0019] [Fig. 5] Schematic overall view, showing the rough (3) just before deformation

[0020] [Fig. 6] Close-up view showing the rough (3) just before deformation

[0021] [Fig. 6B] Close-up view showing another type of rough draft (3), just before deformation

[0022] [Fig.7] Schematic overall view, showing the liner (5) and its end (5b) just after deformation

[0023] [Fig.8] Close-up view showing the end (5b) of the iner just after deformation, the punch (1) having begun to be removed.

[0024] [Fig.9] Schematic overall view, showing the ^2 liner (5) released.

[0025] [Fig. 10] Schematic overall view, showing the 2, F2 liners joined together.

[0026] [Fig. 11] property of "resistance to deformation" of an aluminium, type 1000, depending on the "deformation rate" and temperature.

[0027] [Fig. 12] Evolution of the properties of a mold steel (for example H13 HRC50) depending on the temperature. These properties have been represented as a percentage relative to the values ​​at 21°C of Young's modulus and "tensile strength".

[0028] [Fig. 13] result of numerical simulation, by finite elements, of the reverse spinning.

[0029] [Fig. 14] Close-up showing the optimized draft (3)

[0030] (1) punch

[0031] (1b) extension of the punch (1) i.e.: part used to ensure precise guidance of the punch (1)

[0032] (2) and (4) counterform

[0033] (2b) precision bore, of the counter form, guiding the extension (1b) of the punch (1)

[0034] (3) draft

[0035] (3') and (3”) local overthickness of the blank intended to prevent cooling of the rough draft, by conduction, during the waiting period at the beginning of spinning.

[0036] (5) cylindrical part, of large diameter, of the ^2 metallic liner.

[0037] (5b) cylindrical end, of small diameter, as spun from the ^2 metallic liner

[0038] (5c) transition zone between large (5) and small diameter (5b) of the ^2 metallic liner; area sometimes called dome, area corresponding to the optimized draft

[0039] (5D) entire assembled metal liner (bottle)

[0040] (5D') and (5D”) F2 machined metal liners (half-bottles)

[0041] (5e) threaded bore of the x / i liner 5b'

[0042] (5F) air gap between the punch (1) and the counter form (2) ensuring the calibration of the thickness of the large diameter cylindrical part (5) of the ^2 liner.

[0043] (5b') end, after machining, of the ^2 metallic liner.

[0044] (5') ½ twin metallic liner

[0045] (5'b') end, after machining, of the twin metallic F2 liner

[0046] (5”) connecting zone between the two Vi liners

[0047] (6) punch guide carriage (1)

[0048] (7) carriage guiding means (6)

[0049] (8) and (8') means for heating the metallic Vi liner (5) Further details:

[0050] It should also be noted that the "threaded part" (5e) used for connecting the external piping is obtained by threading the end (5b) of the liner.

[0051] “Second end” called “blind”, having an evolving form, substantially in The entire hemisphere, that is, without any cylindrical part smaller in diameter than the main cylinder, is located at its pole (asymmetrical configuration). This "second end" requires specific reverse spinning tools.

[0052] It is clearly stated that, in the figures, the same references designate the same elements, regardless of the figure in which they appear and regardless of the form in which these elements are represented. Similarly, if elements are not specifically referenced in one of the figures, their references can easily be found by referring to another figure.

[0053] The applicant also wishes to clarify that the figures represent one embodiment of the object according to the invention, but that there may be other embodiments which meet the definition of this invention.

[0054] He further specifies that, when, according to the definition of the invention, the object of the invention comprises “at least one” element having a given function, the embodiment described may comprise several of these elements.

[0055] He also specifies that the term "approximately" can mean that the property thus qualified can be understood either as being exactly or as almost defined. For example, the property "this end of the tube being substantially flush with the end of the insert" can mean either that the end is exactly flush or that it comes within reasonable proximity of the end of the insert.

[0056] It also specifies that, if the embodiments of the object, according to the invention, as illustrated, include several elements of identical function and if, in the description, it is not specified that the object according to this invention must necessarily include a particular number of these elements, the object of the invention may be defined as including “at least one” of these elements.

[0057] Finally, it is specified that when, in the present description, an expression defines by itself, without any particular specific mention concerning it, a set of structural characteristics, these characteristics may be taken, for the definition of the object of the protection sought, when this is technically possible, either separately or in total and / or partial combination. Definition and essential concepts:

[0058] Reverse extrusion (see [Fig. 6]): Reverse extrusion produces a tube with a base (generally called a case, and here referred to as a liner). The extrusion lengths are necessarily relatively short. Reverse extrusion is used for manufacturing armament components (shell casings, warheads, canteens), and gas cylinders made of steel or aluminum alloy. The shapes are limited. Reverse extrusion involves the following steps. Step [A]: The blank (3) (for example, made of aluminum), heated or cooled and lubricated, is placed in a die closed at one end by a block (2) (left-hand drawing [Fig. 3]). Step [B]: A punch (1) pushes on the blank, which is extrusion along the punch, forming a case (5) (center drawing [Fig. 3]). Step [C]: At the end of spinning, the case is ejected by pushing on the block (right drawing [Fig.3]).

[0059] Permeation: see [Fig. 2]; In physics and engineering, permeation is the penetration of a permeate (liquid, gas, or vapor) through a solid. It is directly related to the permeate concentration gradient, the intrinsic permeability of the material, and its mass diffusivity. Permeation is modeled by equations such as Fick's laws of diffusion and can be measured using tools such as a permeameter. Permeation can occur through most materials, including metals, ceramics, and polymers. However, the permeability of metals is much lower than that of ceramics and polymers due to their crystalline structure and low porosity.

[0060] Annealing: Annealing a metal part is a process corresponding to a heating cycle. This cycle consists of a gradual temperature increase, typically to 300°C, followed by a holding period at that temperature. This procedure modifies the physical characteristics of the metal. This action is particularly used to facilitate the relaxation of stresses that may have accumulated within the material under the effect of mechanical or thermal stresses occurring during the synthesis and shaping stages of the materials. During annealing, the grains (single crystals) of material reform and, in a way, regain their "equilibrium state." Crystallization annealing, after work hardening, aims to give the metal an optimal grain size for its future use (bending, stamping, extrusion, etc.).

[0061] Tooling: here, tooling refers to the punch (1) and counter form (2) assembly

[0062] Bottle: in the text, the terms liner and U2 are used interchangeably; a U2 is referred to as a liner. bottle (5D') or (5D”), bottle (5D) designates the set of two U2 bottles. [Fig. 10]. Spinning parameters:

[0063] The spinning ratio ôR is an evaluation of the spinning severity. It is written:

[0064]

[0065]

[0066]

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073]

[0074]

[0075]

[0076]

[0077]

[0078] A' with: h H - 4 s: section of the draft (3) S: section of the spun product (5). Spinning force: Obtaining thin walls of large diameter, in reverse spinning, is extremely delicate; this is why current type III tanks have thick and heavy walls. The spinning force allows us to determine the force required for a given deformation and, in practice, to determine the press that will need to be used. The simplified spinning force is written as: F (daN): force to be applied to the punch (1) R (mm): radius of the blank (3) p(daN / mm2): “resistance to deformation” (see [Fig.l 1]) of the material at the deformation temperature (also called flow stress) θ: ratio between the cross-section of the blank and the cross-section of the finished product at the deformation temperature (called the spinning ratio) 1 (mm): length of the blank f: coefficient of friction between the blank (3) and the walls (1) and (2), this coefficient also depends on the thickness of the wall (5) of the spun 1 / 21er. Deformation rate: The deformation rate of the blank, during reverse spinning, is the derivative, with respect to time, of the deformation e; it is therefore denoted by (epsilon point): g -, It is expressed in s 1 Resistance to deformation: Resistance to deformation, usually denoted by Yf, is defined as the instantaneous value of stress required to continue plastically deforming a material to cause it to flow. The resistance to deformation, for a given material, varies with changes in temperature and the rate of deformation; therefore, we can write: , J1): It is expressed in MPa. Extrudability

[0079] Commercial extrusion alloys: Alloy type Extrudability (% of rate for 5063) 1350 150 1060 135 1100 135 3003 120 6063 100 6061 60 2011 35 5086 25 2014 20 5083 20 2024 15 7075 9 7178 8

[0080] The table above shows the extrudability of aluminum according to its type. All other parameters being equal, extrudability refers to the extrusion speed obtained. Extrudability is derived from the "resistance to deformation", Yf, mentioned above. DESCRIPTION OF THE INVENTION

[0081] The present invention describes the optimal structure of a liner for a composite tank for the storage of gas and in particular hydrogen at high pressure.

[0082] Figure 2 shows the evolution of the permeability of metals as a function of temperature. It can be seen that, at ambient temperature (abscissa 3.4 on the graph), the most interesting metals are, for example and in order of preference: gold, copper, aluminum, austenitic iron, nickel, any other metal or metallic alloy not being excluded from the scope of our claims.

[0083] Except for very specific applications (space applications, for example), we can disregard gold (with a density of 19.3). Copper and aluminum come next. Copper has a density of 8.96, while aluminum has a density of 2.7, which is 3.3 times lower. Furthermore, aluminum has excellent extrudability and good corrosion resistance. We will therefore analyze here, as an example, a liner using this metal, which in no way restricts the scope of the patent to other metals and alloys.

[0084] We have mentioned that aluminum has a permeability 333 times better than HDPE. Within the scope of the invention, we claim to use a liner of thickness "e" in the large-diameter cylindrical zone (5) of between 0.1 mm and 3 mm, within a type III tank; If we consider a composite structure thickness "E" typically having between 16 and 32 mm in thickness, our The claim relates to a range of liner thicknesses relative to composite structure thickness "e / E" between 0.3% and 19%. See the table below. Cover thickness / Liner thickness (mm) 0.1 3 16 0.625% 18.75% 32 0.313% 9.38%

[0086] A type IV HDPE liner has an "e / E" value of 43.9%! Let's take, as an example, our aluminum liner with a reasonable thickness of 0.7 mm, resulting in an "e / E" of 4.54%. With this thickness of 0.7 mm, our permeability performance will be 33.3 times better than a 7 mm HDPE liner. Technologically, the liner will be robust enough to withstand the load during the wrapping of the composite structure; note that it is possible, if necessary, to inflate it to stiffen it, or to fill it, for example, with a frozen fluid.

[0087] The benefits provided by an aluminium liner, for example 0.7 mm thick, in addition to permeability, are as follows (for example for a 62-litre tank) • Reduction in the mass of the liner by 4.1 kg, or 72.3% (the mass goes from 5.7 to only 1.6 kg) (see [Fig. 1]) • Reduction of the composite structure mass of 12 Kg or 29.1% (the mass goes from 41.4 to 29 Kg) such a reduction naturally induces a sharp drop in the material cost of the tank. • Therefore, the total mass of the tank is reduced by 16.1 kg, or 34.3% (the total mass decreases from 47.1 to 30.9 kg) (excluding inserts). Such a reduction is significant in terms of vehicle weight reduction. Our liner is its own insert. • Reduction of the external diameter of the tank by 14.2 mm or 3.4% (the diameter goes from 419.8mm to 405.6 mm) such a reduction is interesting with regard to integration into the vehicle.

[0088] The process for obtaining such a liner (5D) is based on the principle of reverse spinning. DETAILED DESCRIPTION OF THE INVENTION

[0089] As explained previously, our invention consists of producing a type III liner, preferably made of aluminum, having extremely thin walls compared to the state of the art.

[0090] To produce type III liners, manufacturers use type 6000 aluminum. However, since the aluminum will be contained in a composite envelope which will bear all the stresses, it is not necessary to use a structural type 6000 aluminum. Indeed, this is expensive and has a mediocre elongation at break (8%).

[0091] In the context of the invention, we will use a 1000 series aluminum alloy, as it offers: an excellent elongation at break of 25%, and as previously mentioned: The 1000 series is observed to be the most easily extruded. In particular, 1350 offers 160% extrudability compared to 6063. We therefore claim the use of the 1000 series, which consists of 99% or more pure aluminum, namely, but not limited to, the following: 1350, 1199, 1145, 1199, 1100, 1070, 1060, 1050, 1A99, 1A97, 1A95, 1A93, 1A90, 1A85, 1A80, 1A80A!

[0092] Before the reverse spinning operation, it is strategic to have annealed the material.

[0093] During the reverse spinning of ^iners the "spinning ratio" ôR is very unfavorable because the radius of the 'Miner (5) is very large compared to the radius of the blank (3) and because the air gap (5F) (which will control the thickness of the 1 / 21iner in its large diameter (5)) is extremely thin, which causes considerable resistance to the flow of the metal.

[0094] The "spinning force", whose parameters we have given previously, must be minimized: in order not to reach the buckling resistance of the punch (1) and not to require an oversized press.

[0095] Insofar as we have fixed geometric parameters: such as the diameter of the 1 / 21er and the dimension of the air gap (5F) between punch (1) and counter form (2): We have only one parameter left, on which we can act, namely the "Resistance to deformation"!

[0096] The three-dimensional table in [Fig. 11] is the result of our characterization work on a 1000 series aluminum alloy. This table shows the combined effects of the strain rate and temperature on the resistance to deformation. It is observed that the "resistance to deformation" decreases when the strain rate decreases, and that the "resistance to deformation" also decreases when the temperature increases.

[0097] In order to carry out the reverse spinning, according to the invention, we must achieve a value of "Resistance to deformation" which must be less than 20 MPa.

[0098] During the reverse spinning of the blank (3); We therefore claim the strain rate range between 50 s⁻¹ and 0.01 s⁻¹ coupled with the temperature range between 400°C and 645°C. That is to say, the blank (3) must be within this range during the reverse spinning operation.

[0099] It should be noted that the blank, prior to reverse spinning, must be in a state called "annealed" in order to facilitate its shaping by reverse spinning.

[0100] If the blank (3) is heated, for example to 620°C, by the time it is placed in the spinning tooling and the punch is brought close to the blank, it will be able to start cooling down even before the spinning process begins!

[0101] As shown by the numerical simulation of [Fig. 13], for a blank heated to 620°C, if the tooling, punch (1) and counter form (2), has been heated to 380°C, in 49 seconds of compression, the heat exchanges between the aluminum and the steel of the tooling will be such, in the area of ​​the dome (5c), that the aluminum of the blank will drop to 380°C at the beginning of the spinning of the cylindrical part (5) of the U2 liner! the total time, of reverse spinning, being only 52.8 seconds (including 1.58 seconds of punch rise).

[0102] Therefore, the drawing of the tubular part (5), calibrated by the air gap (5F), takes only 2 seconds. If a pre-formed blank with a geometry substantially close to that of the dome is used (see [Fig. 14]), only the tubular part (5) needs to be produced: 1.58 seconds are allowed for approach and tool opening, so a total of 5.16 seconds is required to produce a Fîlincr!

[0103] During reverse spinning, in the presented calculation case: the deformation rate, s*, evolves from 0.018 to 0.19.

[0104] To reduce heat exchange before compression, the blank (3) may have additional thicknesses (3') and (3”), as shown in [Fig. 4]. It is also possible to: increase the deformation rate, and optimize the shape of the blank (3) so that it closely resembles the shape of the dome (5c) (see [Fig. 14]). Such shaping reduces, or even eliminates, the time spent forming the dome (5c), allowing direct extruding of the tubular portion (5) of the Fîlincr. This essentially domed shape (5c) of the blank (3) can be obtained beforehand by: stamping, molding, spinning, machining, or additive manufacturing.

[0105] Note that the "specific heat capacity" (J.kg*.K') is 448 for steel, compared to 921 for aluminum. Therefore, the "volumetric heat capacity" of aluminum is 6 times greater than that of steel!

[0106] In order to reduce heat exchange before compression, an original strategy can be applied: instead of heating the tooling (1) and (2) globally to, for example, 380°C, another approach can be used. This is what we will call "optimized heating".

[0107] If we analyze [Fig. 12], we observe that raising the tooling temperature above 400°C is detrimental to its mechanical strength. However, within the framework of optimized heating: if the tooling is kept at a reasonable temperature, for example 275°C, we claim that raising it to, for example, 600°C is only a very small the thickness of said tooling corresponding to zone (5c) of the dome. Insofar as the steel tooling consists of a punch (1) and a counter form (2), it is sufficient to locally heat one or both of the faces of the tooling opposite zone (5c) of the dome to a thickness at least equal to 3 times the thickness of said zone (5c) of the dome; This optimized, highly localized and very rapid heating can be carried out by any means known to those skilled in the art, such as infrared, induction, or laser heating.

[0108] The blank (3), heated to, for example, 600°C, is rapidly introduced into the counter-form (2). The first principle of optimized heating consists of heating, for example, to 600°C, locally and for a very short time, the area of ​​the tooling where the dome (5c) will be located, and over a thickness at least equal to three times the local thickness of said dome (5c). Only the energy required to cancel any heat transfer between the blank (3) and the tooling (2) and (1) must be supplied. By acting in this way, the blank is maintained at, for example, around 600°C, and the "resistance to deformation" of the blank material (3) is minimized. We claim the following three options for the heated tooling area: either (2) and (1), or (1), or (2).

[0109] The blank (3), heated to, for example, 500°C, is rapidly introduced into the counter-form (2); the second principle, of optimized heating, consists of heating, for example, to 640°C, locally and in a very short time, the area of ​​the tooling where the dome (5c) will be. Only the energy necessary to heat the blank (3) from, for example, 500 to 620°C is applied to this area. This operation is carried out by "unsteady heat transfer" between the cooler blank (3) and the area opposite the tooling, which is hotter, for example, at 640°C. By acting in this way, an "unsteady transfer" of heat is achieved from the tooling to the blank, which allows the tooling to be cooled while simultaneously heating the blank.

[0110] The area of ​​the tooling corresponding to the location of the dome (5c) is precisely heated, the heating being monitored by measuring the energy transmitted, by the chosen heating method and by measuring means, such as infrared or any other measuring means known to those skilled in the art. This heated area, being thin and hotter than the rest of the tooling, expands slightly and is compressed, which improves its mechanical properties.

[0111] Note: it is possible to choose to heat only the area opposite (5c) of the punch (1) or the area opposite (5c) of the counter form, or both areas.

[0112] During spinning, the cylindrical zone (5) tends to cool, resulting in a decrease in diameter... if nothing is done, it then becomes impossible to remove the punch (1) from the cylindrical zone (5) of the liner. Our solution is to heat the cylindrical zone (5) of the liner, using any means known to those skilled in the art. In [Fig. 9] we have shown these means (8) and (8').

[0113] After machining the end (5b') and tapping (5e) the end (5b) of the 1 / 21er, it is then possible to butt-fit the said 1 / 21er (5D') with its twin (5D”). In the case of iners with 0.5 mm walls, this operation requires a temperature differential between the two twins; it can be achieved by heating, for example to 200°C, one of the two iners, aligning it, then sliding it onto its cold twin, and allowing the whole assembly to cool.

[0114] This shrink-fitting can be simple or assisted by brazing or glue.

[0115] If the wall (5) is thicker than 0.5 mm, it is necessary to use two tools of different diameters to avoid shrink-fitting difficulties. Note that butt welding is possible, or a ferrule (short tube) of a suitable diameter, preheated, can also be used to shrink-fit two 1 / 2" tubes of the same diameter and significant thickness.

[0116] Metallic bottles (5D), characterized in that one of the two half-bottles for example (5D”) is blind, that is to say that it does not have an end (5b), but a blind (unpierced) dome (5c)

[0117] First-level precision guidance: It is impossible, with a conventional press, to obtain the guidance precision necessary to produce the ultra-thin wall thicknesses that are the subject of the invention. Therefore, dedicated guiding tooling must be used, which is placed between the press platens. Figures 5 and 7 illustrate the principle of such tooling. This tooling comprises: a guide carriage (6) for the punch (1), which slides along precision columns (7), said columns being embedded in the counter-form (2).

[0118] Second-level precision guidance: to ensure perfect control of the guidance, the punch (1) is extended by an extension (1b). This extension has a dual role: on the one hand, it guarantees the shaping and calibration of the part (5b) of the 1 / 21er (5), and on the other hand, it slides in the calibrated bore (2b) of the "counter-form" (2), thus ensuring perfect guidance of the punch (1) in the counter-form (2).

Claims

Demands

1. A method for obtaining a metal bottle (5D) composed of two half-bottles (5D') and (5D”) obtained from two blanks, the half-bottles being joined end to end by their cylindrical parts, said bottle being intended to serve as a lightweight liner for type III composite tanks, the blank (3) of each half-bottle is placed in a tool consisting of: a counter-form (2) having in its middle a calibrated bore (2b), then vertically above the counter-form is a punch (1), said punch having an extension (1b), said tooling is intended to shape the blank by compression, a compression called reverse drawing, in order to reduce the forces to be exerted by the punch (1) during the production of the half-bottle, the method is characterized in that the blank (3) has been previously treated in the annealed condition,and that the reverse spinning is carried out within a strain rate range of between 50 s⁻¹ and 0.01 s⁻¹*, coupled with a temperature range of said blank between 400°C and 645°C.

2. First version of the optimized method for producing a metallic bottle (5D) composed of 2 half-bottles, according to claim 1, the blank (3) has been preheated to for example 600°C and then rapidly introduced into the counter-form (2), method, characterized: by the fact that it consists of heating to for example 600°C, locally and in a very short time, the area of ​​the tooling where the dome (5c) will be, and over a thickness, depth, at least equal to 3 times the local thickness of said dome (5c), in this procedure, it is necessary to supply just the energy necessary to cancel any heat transfer between the dome (5c) of the blank (3) and the tooling by choosing one of the following three options for the heated tooling area: either the counter-form (2) as well as the punch (1), or only the punch (1), or only the counter-form (2).

3. Second version of the optimized method for manufacturing a metallic bottle (5D) composed of two half-bottles, according to claim 1, the blank (3) has been preheated to, for example, 500°C, then rapidly introduced into the counter-mold (2), the method characterized by the fact that it consists of carrying out an unsteady heat transfer from the tooling to the blank (3), the tooling area being heated to, for example, 640°C, locally and in a very short time, said heated tooling area opposite the dome (5c), being chosen from one of the following three heated tooling area options: either the counter form (2) together with the punch (1), or the punch (1) only, or the counter form (2) only.

4. Optimized method for making a metallic bottle (5D) composed of 2 half-bottles, according to any one of claims 11 3, characterized in that, during the reverse spinning of a bottle, the cylindrical area (5) of the liner is heated with any means known to those skilled in the art.

5. Method for making a metal bottle (5D) composed of 2 half-bottles according to any one of claims 1 to 4 characterized in that, during reverse spinning, to guide the punch (1) a precision guiding tool is used comprising: a guide carriage (6) of the punch (1), this carriage slides along precision columns (7), said columns being embedded in the frame of the counter form (2).

6. Method for making a metal bottle (5D) composed of 2 half-bottles, according to any one of claims 1 to 5 characterized in that during the reverse drawing of a ^2 bottle, to guide the punch (1) in the counter-form (2) an extension (1b) of the punch is used, which slides and is guided by the calibrated bore (2b) of the counter-form (2)

7. Method for making a metal bottle (5D) composed of 2 half-bottles, according to any one of claims 1 to 6, after machining the end (5b') and tapping (5e) the end (5b) of each 1 / 21er (half bottle), it is then possible to join, by shrink fitting, said 1 / 21er (5D') with its twin (5D”), this operation is characterized by the fact that there must be a temperature differential achieved by heating, for example to 200°C, one of the two ^iners, aligning it and then sliding it onto its twin, cold, and allowing the whole to cool, said shrink fitting can be simple or assisted by brazing or glue.

8. A metal bottle (5D) composed of two half-bottles (5D') and (5D”), obtained by the process according to any one of claims 117, characterized by the very small thickness “e” of its cylindrical zone (5) - (5'), thickness between 0.1 mm and 3 mm

9. Metal bottle (5D) composed of 2 half-bottles (5D') and (5D”), according to claim 8, characterized in that the two blanks (3), each of which will allow obtaining a half-metal bottle, are made of one of the following metals: gold, copper, aluminium; said aluminium being chosen to be 99% pure, or more, namely in particular and in a non-exhaustive way among the following references: 1350, 1199, 1145, 1199, 1100, 1070, 1060, 1050, 1A99, 1A97, 1A95, 1A93, 1A90, 1A85, 1A80, 1A80A.

10. Metal bottle (5D) composed of 2 half-bottles (5D') and (5D”), according to claims 8 to 9, during the manufacture of each half-bottle, in order to reduce heat exchange between the blank (3) and the counter-form (2), before reverse spinning, the blank (3) is characterized by the presence of local overthicknesses (3') and (3”).

11. Metal bottle (5D) composed of 2 half-bottles (5D') and (5D”), according to claims 8 to 10, the blank (3), necessary for the manufacture of each half-bottle, is characterized by the fact that the shape of said blank (3) has a geometry very similar to the shape of the dome (5c) to be produced.