New method for producing composite tank, and new composite tank produced by this method

Abstract

To provide the necessity for a storage tank for pressurized fluids with improved quality and reliability of a closing arrangement and of a joining arrangement between the closing arrangement and a first fiber composite shell layer, and a method for producing such a storage tank.SOLUTION: A method for producing a fiber composite tank includes the steps of: assembling a removable molding mandrel; applying an end fitting 11a to the molding mandrel, the end fitting being a metal ring having an opening; forming a first fiber composite shell layer on the molding mandrel and on the end fitting; disassembling and removing the molding mandrel through the opening; shrinking a metal boss 10a by cooling; inserting the metal boss in the opening of the end fitting; and expanding the metal boss by warming. The invention also relates to a fiber composite tank.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a pressurized fluid storage tank.

[0002] More specifically, the present invention relates to a new method for manufacturing a fiber composite tank for containing pressurized fluids, and to the new fiber composite tank obtained by this method. [Background technology]

[0003] Fiber composite cylindrical V-tanks constitute an interesting high-pressure composite tank design suitable for compressed fluid storage for transportation.

[0004] As described in International Patent Application WO 2011 / 143723 by one of the present co-applicants, during the manufacture of a fiber composite tank, a homogeneous liner, preferably made of the same resin as the tank's reinforcing structure, is wrapped around a removable mandrel to ensure the tank's liquid-tightness. This liner is then enveloped by a first fiber composite shell layer, made by wrapping a composite tape made of a fiber-thermoplastic resin composite around the liner. The dome of the first fiber composite shell layer is closed by a closure device, typically comprising an overmolded boss made of metal assembled inside an annular end fitting made of plastic material. This closure device is then overmolded with a second fiber composite shell layer similar to the first fiber composite shell layer to increase the tank's burst pressure.

[0005] When using such a joint, leaks often occur around the dome area, primarily due to the very narrow heat treatment window. Leaks can also appear between the plastic end fitting and the overmolded metal boss and / or between the plastic end fitting and the first fiber composite shell layer due to deformation of the plastic annular end fitting when the resin is heated.

[0006] The present application presents an improvement of the method described in International Patent Application WO 2011 / 143723 to improve the liquid-tightness around the dome region of a fiber composite cylindrical V-tank. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] International Publication No. 2011 / 143723 Summary of the Invention [Problem to be solved by the invention]

[0008] There is a need for a storage tank for pressurized fluids having improved quality and reliability of the closure device and the joining device between the closure device and the first fiber composite shell layer, as well as a need for a convenient method for manufacturing such a storage tank. [Means for solving the problem]

[0009] For this purpose, the invention is based in particular on the use of a closure device for a dome, which comprises a boss made of metal, which is assembled with an interference fit inside an annular end fitting, also made of metal.

[0010] The present invention relates to a method for manufacturing a fiber composite tank for containing a fluid, extending along a longitudinal axis X, comprising the steps of: - assembling a removable forming mandrel; - applying an end fitting to the forming mandrel, said end fitting being a metal ring having an opening surrounded by an annular inner radial surface, said end fitting being large enough to remove the forming mandrel after being disassembled; forming a first fiber composite shell layer on an outer surface of the forming mandrel and on an outer surface of the end fitting to form an extraction orifice for the forming mandrel; - disassembling and removing the forming mandrel through the opening in the end fitting; - shrinking a metal boss by cooling it to a negative temperature, the metal boss having a base with an annular outer radial surface; - inserting the annular outer radial surface of the metal boss in the opening of the end fitting through the extraction orifice; - expanding the metal boss by warming it to a positive temperature, whereby the annular outer radial surface of the metal boss is in sealing contact with the annular inner radial surface of the opening; The present invention relates to a method, comprising:

[0011] The use of a metal ring instead of a plastic ring advantageously prevents deformation during the heating phase designed to solidify the resin of the composite shell layer, thus improving the seal of the tank at the dome. Furthermore, this seal is obtained by shrinking the end fittings before inserting them into the metal ring, and is ensured between the metal ring and the end fittings by a press-fit assembly.

[0012] In an embodiment of the method, forming the first fiber composite shell layer comprises: wrapping a liner film made of a polymer resin around the forming mandrel and the end fittings; - wrapping a composite tape made of a composite material mixed with fibers and polymer resin around the liner film; and - heating or curing the liner film and / or the composite tape to solidify the composite tape and the liner film together; Includes:

[0013] Advantageously, the polymer resin of the liner film and the polymer resin of the composite tape are the same.

[0014] Advantageously, the polymer resin of the liner film and / or the polymer resin of the composite tape is a thermoplastic resin.

[0015] Advantageously, the polymer resin of the liner film and / or composite tape is a polyolefin-based polymer, a polyester-based polymer, a polyacetal-based polymer, a polyaryletherketone (PAEK)-based polymer, a polyamide-based polymer, a thermoplastic polyurethane-based polymer, polyphenylene sulfide (PPS), or a mixture thereof.

[0016] In another embodiment of the method, wrapping the liner film and / or wrapping the composite tape occurs simultaneously with heating the liner film and / or composite tape.

[0017] In a further embodiment of the method, shrinking the metal boss is performed by immersing the metal boss in dry ice made from solid carbon dioxide.

[0018] In an embodiment of the method, the metal boss has a neck that protrudes outside the opening of the end fitting, and the method includes, after expanding the metal boss, performing the following steps: - inserting an annular sealing element into the extraction orifice and in contact around the neck; Includes:

[0019] Advantageously, the annular sealing element is made of a polymeric resin, preferably a thermoplastic resin.

[0020] In an embodiment of the method, the metal boss has a neck that protrudes outside the opening of the end fitting, and the method includes, after expanding the metal boss, performing the following steps: forming a second fiber composite shell layer on the first fiber composite shell layer and the annular sealing element; Includes:

[0021] In another embodiment of the method, forming the second fiber composite shell layer comprises: - wrapping a composite tape made of a composite material mixed with fibers and a polymer resin around the first fiber composite shell layer and the annular sealing element; and - heating the composite tape to co-solidate the first fiber composite shell layer and the second fiber composite shell layer; Includes:

[0022] Advantageously, the polymer resin of the annular sealing element, the first fiber composite shell layer and the second fiber composite shell layer is the same.

[0023] Advantageously, the polymer resin of the annular sealing element, the first fiber composite shell layer and / or the second fiber composite shell is a thermoplastic resin.

[0024] Advantageously, the polymer resin of the annular sealing element, the first fiber composite shell layer and the second fiber composite shell layer is a polyolefin-based polymer, a polyester-based polymer, a polyacetal-based polymer, a polyaryletherketone (PAEK)-based polymer, a polyamide-based polymer, a thermoplastic polyurethane-based polymer, polyphenylene sulfide (PPS), or a mixture thereof.

[0025] Advantageously, the fibers of the composite tape include carbon fibers, glass fibers and / or basalt fibers.

[0026] Another aspect of the invention relates to a product obtained from the method according to the invention, a fiber composite tank for containing a fluid, which comprises: a first fiber composite shell layer; a metal boss having a base with an annular outer radial surface; an end fitting which is a metal ring having an opening surrounded by an annular inner radial surface; Equipped with The annular outer radial surface of the metal boss is in sealing contact with the annular inner radial surface of the opening.

[0027] Thus, the fiber composite tank obtained by this method can be produced with improved liquid-tightness and can withstand an overpressure of at least 2 bar.

[0028] Advantageously, the metal boss has a neck that projects outside the extraction orifice, and the fiber composite tank also has an annular sealing element arranged in contact with the extraction orifice around the neck; a second fiber composite shell layer bonded to the first fiber composite shell layer and to the annular sealing element; Equipped with.

[0029] Advantageously, the inner surface of the end fitting and the inner surface of the metal boss received inside the end fitting form a slope converging towards the outside of the fibre composite tank.

[0030] Advantageously, at least one of the end fitting and the base of the metal boss is provided with at least one backdraft-shaped recess in its outer surface.

[0031] Advantageously, the backdraft-shaped recess is in the form of a backdraft-shaped groove.

[0032] Advantageously, the backdraft shaped grooves have a fishtail, polygonal, circular or elliptical cross section.

[0033] Advantageously, at least one of the end fitting and the base of the metal boss is provided with at least one raised feature on an outer surface.

[0034] Advantageously, the fibre composite tank further comprises an annular seal provided between the annular outer radial surface of the metal boss and the annular inner radial surface of the end fitting.

[0035] Advantageously, the annular seal is an O-ring seal or an injection seal formed by injecting an elastomeric material, and is housed in two opposing annular grooves, one annular groove in the annular inner radial surface of the end fitting and one annular groove in the annular outer radial surface of the metal boss.

[0036] Advantageously, the end fitting has an annular outer radial surface that is thinner than an annular inner radial surface.

[0037] Advantageously, the annular outer radial surface is in the form of an inclined ridge.

[0038] Advantageously, the annular inner radial surface of the opening in the end fitting and the annular outer radial surface of the metal boss are cylindrical about the longitudinal axis X.

[0039] Advantageously, the annular inner radial surface of the opening in the end fitting and the annular outer radial surface of the metal boss are frustoconical about the longitudinal axis X.

[0040] The present invention is further explained in the accompanying drawings and description of the drawings which illustrate preferred embodiments of the invention. Note that the drawings are not drawn to scale. The drawings are intended to illustrate the principles of the invention. [Brief explanation of the drawings]

[0041] [Figure 1] 1 illustrates the main steps of a method for manufacturing a fiber composite tank according to the invention. [Figure 2] 1 is a perspective schematic view of a partially assembled forming mandrel suitable for carrying out the method of manufacturing a fiber composite tank according to the invention; [Figure 3] 3 is a schematic profile view of the assembled forming mandrel of FIG. 2 with two end fittings. [Figure 4] 4 is a perspective schematic view of a fiber composite shell layer wrapped around the assembled forming mandrel of FIG. 3. FIG. [Figure 5] Figures 5 to 7 are schematic cross-sectional views of the dome of a fiber composite tank according to the invention, illustrating the following steps of a method for manufacturing a fiber composite tank: Figure 5 shows the step of inserting a metal boss into the opening of an overmolded end fitting. [Figure 6]Figures 5 to 7 are schematic cross-sectional views of the dome of a fiber composite tank according to the invention, illustrating the following steps of the method for manufacturing a fiber composite tank: Figure 6 is the step of inserting an annular composite adapted sealing element into the extraction orifice, in contact around the neck of the metal boss. [Figure 7] 5 to 7 are schematic cross-sectional views of the dome of a fiber composite tank according to the invention, illustrating the following steps of a method for manufacturing a fiber composite tank: Fig. 7 shows the step of forming a second fiber composite shell layer on the first fiber composite shell layer and the annular sealing element. [Figure 8] FIG. 1 is a schematic perspective view of the dome of a fiber composite tank according to the present invention, illustrating the step of inserting a metal boss into the opening of the end fitting, wherein the outer surface of the end fitting and the outer surface of the base of the metal boss both comprise two concentric backdraft-shaped grooves and a hemispherical raised shape, and two opposing annular grooves are provided on the annular outer radial surface of the metal boss and the annular inner radial surface of the end fitting to accommodate injected elastomeric material. [Figure 9] 9 is a schematic view similar to FIG. 8, except that the raised features are pyramidal and two opposing annular grooves are provided to accommodate O-ring seals. [Figure 10] FIG. 7 is a detailed view of the circled portion of FIG. 6, in which the backdraft-shaped groove has a fishtail cross section. [Figure 11] FIG. 7 is a detailed view of the circled portion of FIG. 6, in which the backdraft-shaped groove has a diamond-shaped cross section. [Figure 12] FIG. 7 is a detailed view of the circled portion of FIG. 6, in which the backdraft-shaped groove has an oval-shaped cross section. [Figure 13] FIG. 7 is a detailed view of the circled portion of FIG. 6, in which the backdraft-shaped groove has a rectangular-shaped cross section. [Figure 14] FIG. 7 is a detailed view of the circled portion of FIG. 6, in which the annular inner radial surface of the end fitting and the annular outer radial surface of the metal boss are frustoconical rather than cylindrical about the longitudinal axis X. [Figure 15]FIG. 7 is a detailed view of the circled portion of FIG. 6, showing the elastomeric material being injected into the metal boss and two opposing annular grooves in the end fitting. The device can be used until the second tape wrap is completed, if desired. [Figure 16] 15 is a detailed view of the circled portion of FIG. 6, with O-ring seals provided in the two opposing annular grooves of FIG. 15. DETAILED DESCRIPTION OF THE INVENTION

[0042] Unless otherwise specified, identical elements appearing in different figures will have a single reference number.

[0043] Furthermore, terms such as "first," "second," etc. in the specification and claims are used to distinguish between similar elements and are not necessarily intended to describe a sequential or chronological order.

[0044] The present invention relates to a new method for manufacturing a fiber composite tank 1 for containing a pressurized fluid, and to the new fiber composite tank 1 obtained by this method. Hereinafter, the fiber composite tank 1 of the present invention will be referred to simply as "tank".

[0045] The pressurized fluid may be a pressurized gas, a pressurized liquid, or a mixture thereof.

[0046] Preferably, the tank 1 is cylindrical and has an internal volume ranging, for example, from 60 liters to 2000 liters or more.

[0047] Tank 1 can contain many different types of fluids. "Fluid" means gas or liquid. Examples of gases that can be contained in Tank 1 are hydrogen, helium, nitrogen, krypton, water, alkali, liquid acid, or compressed natural gas (CNG). Tank 1 can contain any type of gas or liquid.

[0048] The tank 1 comprises an inner first fiber composite shell layer 2, preferably comprising a liner film 3 made of a polymer resin, preferably a thermoplastic resin, and a composite tape 4 made of a composite material of a mixture of fibers and a polymer resin, preferably a thermoplastic resin, which is wrapped around the liner film 3 and solidified together with the liner film 3.

[0049] The tank 1 preferably comprises an optional second textile composite shell layer 5, which may also comprise a composite tape 4 made of a composite material that mixes fibers with a polymer resin, preferably a thermoplastic resin. The presence of the second textile composite shell layer 5 depends on the value of the pressure that the tank 1 has to withstand. Typically, the second textile composite shell layer 5 is required to increase the burst pressure of the tank, for example if the tank 1 has to withstand pressures of the order of 50 bar or more.

[0050] The second fiber composite shell layer 5 also reduces permeation through the tank 1 .

[0051] According to an embodiment, the tank 1 is mainly cylindrical and extends along a longitudinal axis X, with two domes 6a, 6b facing each other, one at each of the two opposite ends of the tank 1. At least one dome 6a, 6b has an opening forming an extraction orifice 7 large enough to allow disassembly and removal of the forming mandrel 8 through the opening (see further).

[0052] At least one dome having an extraction orifice 7 is provided with a closure device 9a, 9b comprising a metal boss 10a, 10b and end fittings 11a, 11b assembled in a tight arrangement around the metal boss 10a, 10b.

[0053] The first fiber composite shell layer 2 and the second fiber composite shell layer 5 preferably result in a monolithic layer made of a composite structure comprising an assembly of closure devices 9a, 9b comprising metal bosses 10a, 10b and end fittings 11a, 11b assembled in close arrangement to one another.

[0054] The metal bosses 10a, 10b have bases 12a, 12b with annular outer radial surfaces 13a, 13b, and the end fittings 11a, 11b are metal rings having openings 14a, 14b surrounded by annular inner radial surfaces 15a, 15b, the annular outer radial surfaces 13a, 13b of the metal bosses 10a, 10b being in sealing contact with the annular inner radial surfaces 15a, 15b of the openings 14a, 14b of the end fittings 11a, 11b. At least one of the end fittings 11a, 11b, and preferably each of the fittings 11a, 11b, is made of a metal such as aluminum, an aluminum alloy, steel, or stainless steel.

[0055] Similarly, in a preferred embodiment, at least one metal boss 10a, 10b, preferably each, is made of a metal, such as aluminum, an aluminum alloy, steel, or stainless steel.

[0056] The annular outer radial surfaces 13a, 13b of the metal bosses 10a, 10b and the annular inner radial surfaces 15a, 15b of the end fittings 11a, 11b preferably have complementary shapes. At room temperature, the diameters of the annular outer radial surfaces 13a, 13b of the metal bosses 10a, 10b are preferably slightly larger than the diameters of the annular inner radial surfaces 15a, 15b of the end fittings 11a, 11b.

[0057] In a preferred embodiment, the annular inner radial surfaces 15a, 15b of the openings 14a, 14b in the end fittings 11a, 11b and the annular outer radial surfaces 13a, 13b of the metal bosses 10a, 10b are both cylindrical (see FIGS. 10 to 13) or frustoconical (see FIG. 14) about the longitudinal axis X. The frustoconical shape makes it easier to introduce the metal bosses 10a, 10b inside the openings 14a, 14b in the end fittings 11a, 11b, resulting in self-centering. The cone angle α of the frustoconical shape relative to the longitudinal axis X is preferably between 1° and 20°, more preferably between 3° and 15°, and even more preferably between 5° and 10°.

[0058] The closure devices 9 a, 9 b are overmolded with a first textile composite shell layer 2 and an optional second textile composite shell layer 5 .

[0059] The metal bosses 10a, 10b preferably have necks 16a, 16b that project outside the openings 14a, 14b of the end fittings 11a, 11b.

[0060] In a preferred embodiment, the tank 1 also comprises at least one annular sealing element 17 arranged around and in contact with the extraction orifice 7 at the neck 16a, 16b. The annular sealing element 17 is intended to fill most of the empty volume that may be present at the extraction orifice 7 between the first fiber composite shell layer 2 and the neck 16a, 16b of the metal boss 10a, 10b. It is preferably made from a polymer resin, more preferably a thermoplastic resin. The optional second fiber composite shell layer 5 is preferably bonded to the first fiber composite shell layer 2 and the annular sealing element 17 to form an integral, rigid structure capable of withstanding an overpressure of at least 2 bar.

[0061] Preferably, the polymer resins of the annular sealing element 17, the first fiber composite shell layer 2 and the second fiber composite shell layer 5 are the same or chemically compatible and are preferably a polyolefin-based polymer, such as polypropylene (PP), a polyester-based polymer, such as polyethylene terephthalate (PET), a polyacetal-based polymer, such as polyoxymethylene (POM), a polyaryletherketone (PAEK)-based polymer, such as polyetherketoneketone (PEKK) or polyetheretherketone (PEEK), a polyamide-based polymer, such as polyamide 6 (PA6), polyamide 11 (PA11), polyamide 12 (PA12), polyamide 66 (PA66) or polyphthalamide (PPA), a thermoplastic polyurethane-based polymer, polyphenylene sulfide (PPS), or a mixture thereof.

[0062] In a preferred embodiment, the end fittings 11a, 11b have annular outer radial surfaces 18a, 18b that are thinner than the annular inner radial surfaces 15a, 15b. The end fittings 11a, 11b therefore have a generally triangular cross section. The annular outer radial surfaces 18a, 18b are preferably in the form of angled ridges.

[0063] In a preferred embodiment, the inner surfaces 19a, 19b of the end fittings 11a, 11b and the inner surfaces 20a, 20b of the metal bosses 10a, 10b received inside the end fittings 11a, 11b form a slope 21 that converges towards the outside of the tank 1, i.e., towards the free ends of the necks 16a, 16b. This slope 21 can be linear or stepped, without any form of retention. Thus, for example, liquid used in a hydraulic test can easily be drained from the tank 1 by gravity, especially after the hydraulic test, when the tank 1 is turned upside down so that the necks 16a, 16b are facing downwards.

[0064] In a preferred embodiment, the outer surfaces 22a, 22b of the end fittings 11a, 11b and / or the outer surfaces 23a, 23b of the bases 12a, 12b of the metal bosses 10a, 10b, respectively, are provided with at least one backdraft-shaped recess 24, 25. The backdraft-shaped recess 24, 25 may be in the form of, for example, at least one fishtail (see FIG. 10), polygonal (see FIGS. 11 and 13), circular or elliptical (see FIG. 12) cross-section.

[0065] The backdraft-shaped recesses 24, 25 allow the resin to penetrate inside. The backdraft-shaped recesses 24 in the end fittings 11a, 11b improve the bond between the first fiber composite shell layer 2 and said end fittings 11a, 11b, while the backdraft-shaped recesses 25 in the metal bosses 10a, 10b improve the bond between the second fiber composite shell layer 5 or the annular sealing element 17 and said metal bosses 10a, 10b. During the process, the polymer should fill all backdraft-shaped recesses 24, 25 so that air voids are avoided to the greatest extent possible.

[0066] To improve liquid tightness, the backdraft-shaped recesses 24, 25 may be filled with a polymer powder of the same or compatible chemistry as the polymer liner film 3 wrapped around the mandrel 8 and partially consolidated by any suitable means.

[0067] The dimensions of the backdraft-shaped recesses 24, 25 are preferably selected so that they are large enough for the resin to fill them, but small enough so as not to weaken the end fittings 11a, 11b and / or the provided metal bosses 10a, 10b.

[0068] In a preferred embodiment, the outer surface 22a, 22b of the end fitting 11a, 11b and / or the outer surface 23a, 23b of the base 12a, 12b of the metal boss 10a, 10b is provided with at least one raised feature 26, 27 that prevents the end fitting 11a, 11b and / or the metal boss 10a, 10b from rotating about the longitudinal axis X relative to the first fiber composite shell layer 2 or the annular sealing element 17.

[0069] For example, the raised shapes 26, 27 can be hemispherical (see FIG. 8) or pyramidal (see FIG. 9). Any other raised shape is suitable.

[0070] In a preferred embodiment, the tank 1 further includes an annular seal 28 disposed between the annular outer radial surfaces 13a, 13b of the metal bosses 10a, 10b and the annular inner radial surfaces 15a, 15b of the end fittings 11a, 11b. The annular seal 28 is preferably disposed in two opposing annular grooves 29, 30, with one annular groove 30 disposed in the annular inner radial surfaces 15a, 15b of the end fittings 11a, 11b and one annular groove 29 disposed in the annular outer radial surfaces 13a, 13b of the metal bosses 10a, 10b. For example, the annular seal 28 can be an O-ring seal 281 (see FIGS. 9 and 16) formed by injecting an elastomeric material, or an injection seal 282 (see FIG. 15). The elastomeric material is preferably injected from the outside of the tank 1 through a channel 31 which leads to two opposing annular grooves 29, 30, the channel 31 being formed by two opposing notches 32, 33, one notch 32 fitting into the annular inner radial surfaces 15a, 15b of the end fittings 11a, 11b and the other notch 33 fitting into the annular outer radial surfaces 13a, 13b of the metal bosses 10a, 10b (see Figure 8).

[0071] In addition to the press fit, in the highly unlikely event that there is not enough clamping strength to make a second wrap, an elastomeric material—similar to the annular seal 28 or O-ring seal 281 (28, 281)—or epoxy beads may be used on the surface only between the metal bosses 10a, 10b and the end fittings 11a, 11b.

[0072] Subsequently, a method for manufacturing a tank 1 according to the invention will be described (see FIG. 1). This method is an improvement of the method described in International Patent Application WO 2011 / 143723 and includes the common steps described below. A more detailed description of these common steps can be found in the above-mentioned International Patent Application.

[0073] In step S1, a reusable and removable forming mandrel 8 is assembled.

[0074] FIG. 3 shows an example of a reusable, removable forming mandrel 8 that can be used in the methods herein. The mandrel 8 comprises multiple elongated segments 34 arranged side by side to form a rounded outer surface. The mandrel 8 has a rotationally symmetric shape with an outer diameter that varies about a longitudinal axis of symmetry X, making it suitable for wrapping films and tapes. This geometry allows flexibility in the selection of the shape of the tank 1 to be manufactured. The tank 1 may be cylindrical, spherical, elliptical, or any other shape.

[0075] The elongated segment 34 of the mandrel 8 is made of a metal, such as aluminum, an aluminum alloy, steel, or stainless steel.

[0076] As shown in FIG. 2, during assembly of the mandrel 8, the elongated segments 34 are held together using, for example, a segment holder 35 and two spindle portions 36a, 36b. The elongated segments 34 are held in place by pulling the spindle portions 36a, 36b away from each other. The segment holder 35 is mounted to the spindle portions 36a, 36b for engaging opposite ends of the elongated segments 34. For illustrative purposes, FIG. 2 shows a subset of the elongated segments 34 held by two segment holders 35 disposed on the two spindle portions 36a and 36b.

[0077] In step S2, at least one end fitting 11a, 11b is applied to the assembled mandrel 8. To apply the end fittings 11a, 11b to the assembled mandrel 8, the end fittings 11a, 11b are shifted onto one of the spindle portions 36a, 36b. FIG. 3 shows the assembled mandrel 8 with two end fittings 11a, 11b applied. Alternatively, only one end fitting 11a, 11b may be applied to the assembled, removable mandrel 8. Each end fitting 11a, 11b is a metal ring bounded by an annular inner radial surface 15a, 15b and provided with openings 14a, 14b large enough to permit disassembly and removal of the mandrel 8 therethrough.

[0078] Each end fitting 11a, 11b remains in place after the tank 1 is manufactured.

[0079] After step S2, step S3 is performed, in which a first fiber composite shell layer 2 is formed on the outer surface 37 of the forming mandrel 8 and on the outer surfaces 22a, 22b of the end fittings 11a, 11b to form an extraction orifice 7 for the forming mandrel 8 large enough to allow disassembly and removal of the mandrel 8 through the extraction orifice 7.

[0080] In a preferred embodiment, step S3 comprises the following steps: a step S3a of wrapping a liner film 3 made of polymer resin around the forming mandrel 8 and the end fittings 11a, 11b; a step S3b of winding a composite tape 4 made of a composite material of a mixture of fibers and a polymer resin around the liner film 3; and a step S3c of heating the liner film 3 and the composite tape 4 in order to bond the composite tape 4 and / or the liner film 3 together; Includes.

[0081] If the polymer resin is a thermoplastic resin, the first fiber composite shell layer 2 may be solidified by heating, by curing with a chemical activator, or by other methods.

[0082] Step S3 of forming the first fiber composite shell layer 2 can also be carried out under heat and pressure by a winding machine, the pressure condition resulting from tension applied to the liner film 3 and the composite tape 4 during winding, and the heat condition being achieved, for example, by diode, microwave, infrared, or any other heating means.

[0083] Preferably, step S3a of wrapping the liner film 3 and / or step S3b of wrapping the composite tape 4 are performed simultaneously with step S3c of heating the liner film 3 and / or the composite tape 4. Heating can also be performed after each wrapping.

[0084] For example, the fibers may be high-strength fibers such as carbon fibers, glass fibers, and / or basalt fibers impregnated with a polymer resin, preferably a thermoplastic resin, such as a polyolefin-based polymer, e.g., polypropylene (PP), a polyester-based polymer, e.g., polyethylene terephthalate (PET), a polyacetal-based polymer, e.g., polyoxymethylene (POM), a polyaryletherketone (PAEK)-based polymer, e.g., polyetherketoneketone (PEKK) or polyetheretherketone (PEEK), a polyamide-based polymer, e.g., polyamide 6 (PA6), polyamide 11 (PA11), polyamide 12 (PA12), polyamide 66 (PA66), or polyphthalamide (PPA), a thermoplastic polyurethane-based polymer, polyphenylene sulfide (PPS), or mixtures thereof.

[0085] The polymer resin of the liner film 3 and the polymer resin of the composite tape 4 are preferably the same or chemically compatible.

[0086] A detailed description of the winding process and parameters can be found in International Patent Application WO 2011 / 143723.

[0087] When the end fittings 11a, 11b have outer surfaces 22a, 22b provided with at least one backdraft-shaped recess 24, some of the resin of the first fiber composite shell layer 2 penetrates inside the at least one backdraft-shaped recess 24, improving the bond between the first fiber composite shell layer 2 and the end fittings 11a, 11b.

[0088] FIG. 4 shows the assembled mandrel 8 with the first fiber composite shell layer 2 formed on its outer surface 37 and on the outer surfaces 22a, 22b of the end fittings 11a, 11b.

[0089] Once the first fiber composite shell layer 2 has been formed, in a next step S4 the mandrel 8 is disassembled and its different parts are removed from the tank 1 through the openings 14a, 14b in at least one end fitting 11a, 11b. Disassembly can be performed as follows: pushing the spindle parts 36a, 36b into the interior of the tank 1, removing the segment holders 35 from the spindle parts 36a, 36b (e.g., by inserting a hand inside the hollow spindle parts 36a, 36b), taking the spindle parts 36a, 36b out of the tank 1, and removing the segment holders 35 and elongated segments 34 from the tank 1 through the openings 14a, 14b in the end fittings 11a, 11b while leaving the end fittings 11a, 11b in place.

[0090] After the mandrel 8 has been completely disassembled and removed from the tank 1, in the following step S5 the metal bosses 10a, 10b are shrunk by cooling them to a negative temperature. By "shrunk" we mean that the dimensions of the metal bosses 10a, 10b become smaller than their normal dimensions at room temperature.

[0091] Step S5 of shrinking the metal bosses 10a, 10b is preferably performed by immersing the metal bosses 10a, 10b in dry ice made from solid carbon dioxide, for example at a temperature of about -80°C.

[0092] Once the metal bosses 10a, 10b have been shrunk, in the next step S6, the annular outer radial surfaces 13a, 13b of the metal bosses 10a, 10b are inserted through the extraction orifices 7 into the openings 14a, 14b of the end fittings 11a, 11b (see Figures 5, 8 and 9). This insertion step S6 is easier if the annular inner radial surfaces 15a, 15b of the openings 14a, 14b of the end fittings 11a, 11b and the annular outer radial surfaces 13a, 13b of the metal bosses 10a, 10b are both frustoconical about the longitudinal axis X, have the same taper, and the frustoconical shape opens towards the outside of the tank 1. The frustoconical shape also provides self-centering for the metal bosses 10a, 10b and the end fittings 11a, 11b.

[0093] After step S6, step S7 is performed, in which the metal bosses 10a, 10b inserted into the end fittings 11a, 11b are expanded by warming them to a positive temperature, preferably room temperature. "Expanded" means that the dimensions of the metal bosses 10a, 10b are larger than their dimensions at a negative temperature. Thus, the dimensions of the "expanded" metal bosses 10a, 10b may be the same as their normal dimensions at room temperature. While expanding, the annular outer radial surfaces 13a, 13b of the metal bosses 10a, 10b make intimate and sealing contact with the annular inner radial surfaces 15a, 15b of the openings 14a, 14b in the end fittings 11a, 11b.

[0094] In a preferred embodiment, following the expansion of the metal bosses 10a, 10b, an additional optional step S8 is carried out in which an annular sealing element 17 is inserted into the extraction orifice 7 in contact around the necks 16a, 16b in any gap that may exist in the extraction orifice 7 between the first fiber composite shell layer 2 and the necks 16a, 16b of the metal bosses 10a, 10b (see Figure 6).

[0095] The annular sealing element 17 is preferably made from a polymer resin, preferably from a thermoplastic resin, even more preferably from a polyolefin-based polymer such as polypropylene (PP), a polyester-based polymer such as polyethylene terephthalate (PET), a polyacetal-based polymer such as polyoxymethylene (POM), a polyaryletherketone (PAEK)-based polymer such as polyetherketoneketone (PEKK) or polyetheretherketone (PEEK), a polyamide-based polymer such as polyamide 6 (PA6), polyamide 11 (PA11), polyamide 12 (PA12), polyamide 66 (PA66), or polyphthalamide (PPA), a thermoplastic polyurethane-based polymer, polyphenylene sulfide (PPS), or a mixture thereof.

[0096] In a preferred embodiment, the annular sealing element 17 is bonded to the first fiber composite shell layer 2 and the metal bosses 10a, 10b and then heated during step S8 or a subsequent step to form an integral rigid structure capable of withstanding an overpressure of at least 2 bar.

[0097] When the metal bosses 10a, 10b have bases 12a, 12b with at least one backdraft-shaped recess 25 provided in their outer surfaces 23a, 23b, a portion of the annular sealing element 17 penetrates inside the at least one backdraft-shaped recess 25, improving the bond between the annular sealing element 17 and the metal bosses 10a, 10b.

[0098] In a preferred embodiment, following step S7 of expanding the metal bosses 10a, 10b and / or step S8 of inserting the annular sealing element 17 into the extraction orifice 7, an additional optional step S9 is performed in which a second fiber composite shell layer 5 is formed on the first fiber composite shell layer 2 and, if present, the annular sealing element 17 (see Figure 7).

[0099] In a preferred embodiment, the second fiber composite shell layer 5 is formed by the following steps: a step S9a of winding a composite tape 4 made of a composite material of a mixture of fibers and a polymer resin around the first fiber composite shell layer 2 and the annular sealing element 17, and a step S9b of heating the composite tape 4 in order to solidify both the first fiber composite shell layer 2 and the second fiber composite shell layer 5; It can be formed according to

[0100] Step S9 of forming the second fiber composite shell layer 5 can also be performed under heat and pressure by a winding machine, the pressure condition resulting from the tension applied to the composite tape 4 during winding, and the heat condition being achieved, for example, by diode, microwave, infrared, or any other heating means.

[0101] It is preferable that step S9a of winding the composite tape 4 and step S9b of heating the composite tape 4 are carried out simultaneously.

[0102] For example, the fibers may be high-strength fibers such as carbon fibers, glass fibers, and / or basalt fibers impregnated with a polymer resin, preferably a polyolefin-based polymer such as polypropylene (PP), a polyester-based polymer such as polyethylene terephthalate (PET), a polyacetal-based polymer such as polyoxymethylene (POM), a polyaryletherketone (PAEK)-based polymer such as polyetherketoneketone (PEKK) or polyetheretherketone (PEEK), a polyamide-based polymer such as polyamide 6 (PA6), polyamide 11 (PA11), polyamide 12 (PA12), polyamide 66 (PA66), or polyphthalamide (PPA), a thermoplastic polyurethane-based polymer, polyphenylene sulfide (PPS), or mixtures thereof.

[0103] In a preferred embodiment, the composite tapes 4 of the first and second fiber composite shell layers 2, 5 may be the same. The polymer resins of the first and second fiber composite shell layers 2, 5 are also preferably the same. If the annular sealing element 17 is present, the polymer resin of the second fiber composite shell layer 5 and the polymer resin of the annular sealing element 17 are also preferably the same, for example a polyolefin-based polymer, a polyester-based polymer, a polyacetal-based polymer, a polyaryletherketone (PAEK)-based polymer, a polyamide-based polymer, a thermoplastic polyurethane-based polymer, polyphenylene sulfide (PPS), or a mixture thereof.

[0104] During step S9 of forming the second fiber composite shell layer 5, the second fiber composite shell layer 5 is preferably bonded to the first fiber composite shell layer 2 and, if present, the annular sealing element 17, to form an integral, rigid structure capable of withstanding the overpressure for which the cylinder is designed.

[0105] In a preferred embodiment, the annular seals 28 are received in two opposing annular grooves 29, 30 provided between the annular outer radial surfaces 13a, 13b of the metal bosses 10a, 10b and the annular inner radial surfaces 15a, 15b of the end fittings 11a, 11b.

[0106] If the annular seal 28 is an O-ring seal 281, it is manually fitted, for example, into one of the two opposing annular grooves 29, 30 before step S6 of inserting the metal bosses 10a, 10b into the end fittings 11a, 11b (see Figures 9 and 16).

[0107] If the annular seal 28 is an injection seal 282, the elastomeric material is injected into a ring-shaped channel 31 formed by two opposing annular grooves 29, 30 after step S6 of inserting the metal bosses 10a, 10b into the end fittings 11a, 11b and before optional steps S8 and S9 of inserting the annular sealing element 17 to form the second fiber composite shell layer 5 (see Figures 8 and 15). Injecting the elastomeric material is performed from the outside of the tank 1, with at least one channel being formed by two mutually facing notches 32, 33 provided in the annular inner radial surfaces 15a, 15b of the end fittings 11a, 11b and in the annular outer radial surfaces 13a, 13b of the metal bosses 10a, 10b, respectively.

[0108] The annular seal 28 improves the fluid-tight seal between the metal boss 10a, 10b and the end fitting 11a, 11b into which it is inserted, especially when the annular outer radial surface 13a, 13b of the metal boss 10a, 10b and the annular inner radial surface 15a, 15b of the end fitting 11a, 11b are not perfectly complementary.

[0109] A separate sealant or adhesive may be provided between the annular outer radial surfaces 13a, 13b of the metal bosses 10a, 10b and the annular inner radial surfaces 15a, 15b of the end fittings 11a, 11b, not necessarily inside the grooves.

[0110] The present invention can be used to manufacture a wide variety of fiber composite tanks for a variety of applications, such as containers for the storage of hydrogen, helium, nitrogen, krypton, water, alkali, liquid acid, or compressed natural gas (CNG), etc. The size of the tank 1 can range from 60 L to 2000 L, or even more. [Explanation of symbols]

[0111] 1. Fiber composite tank 2. First fiber composite shell layer 3 Liner film 4 Composite Tape 5 Second fiber composite shell layer 6a, 6b Dome 7 Extraction Orifice 8 mandrels 9a, 9b Closing device 10a, 10b Metal boss 11a, 11b End fittings 12a, 12b base 13a, 13b outer radial surface 14a, 14b opening 15a, 15b Inner radial surface 16a, 16b neck 17 Annular sealing element 18a, 18b outer radial surface 19a, 19b Inner surface of end fitting 20a, 20b Inner surface of metal boss 21 Incline 22a, 22b Outer surface of end fitting 23a, 23b Outer surface of base 24, 25 recess 26, 27 Raised shape 28 Annular seal 29, 30 Annular groove 31 channels 32, 33 notches 34 segments 35 Segment holder 36a, 36b Spindle part 37 Exterior 281 O-ring seal 282 Injection Seal V Fiber composite cylindrical type X Longitudinal Axis α angle

Claims

1. A method for manufacturing a fiber composite tank (1) for containing a fluid, extending along a longitudinal axis (X), comprising the steps of: - Assembling (S1) a removable forming mandrel (8), - applying (S2) end fittings (11a, 11b) to the forming mandrel (8), said end fittings (11a, 11b) being metal rings having openings (14a, 14b) surrounded by annular inner radial surfaces (15a, 15b), and large enough to allow removal of the forming mandrel (8) after disassembly (S2); - forming (S3) a first fiber composite shell layer (2) on the outer surface (37) of the forming mandrel (8) and on the outer surfaces (22a, 22b) of the end fittings (11a, 11b) to form extraction orifices (7) for the forming mandrel (8); - disassembling and removing (S4) the forming mandrel (8) through the openings (14a, 14b) of the end fittings (11a, 11b); - a step (S5) of shrinking the metal bosses (10a, 10b) by cooling them to a negative temperature, the metal bosses (10a, 10b) having bases (12a, 12b) with annular outer radial surfaces (13a, 13b); - inserting (S6) the annular outer radial surfaces (13a, 13b) of the metal bosses (10a, 10b) in the openings (14a, 14b) of the end fittings (11a, 11b) through the extraction orifices (7); - expanding (S7) the metal bosses (10a, 10b) by warming them to a positive temperature, so that the annular outer radial surfaces (13a, 13b) of the metal bosses (10a, 10b) come into sealing contact with the annular inner radial surfaces (15a, 15b) of the openings (14a, 14b) of the end fittings (11a, 11b); A method comprising:

2. The forming (S3) of the first fiber composite shell layer (2) comprises the following steps: - wrapping (S3a) a liner film (3) made of polymer resin around the forming mandrel (8) and the end fittings (11a, 11b), - wrapping (S3b) a composite tape (4) made of a composite material of a mixture of fibers and polymer resin around the liner film (3); and - heating or curing the liner film (3) and / or the composite tape (4) to solidify the composite tape (4) and the liner film (3) together (S3c); 2. The method of claim 1, comprising:

3. 3. The method according to claim 2, characterized in that the polymer resin of the liner film (3) and the polymer resin of the composite tape (4) are the same.

4. 4. The method according to claim 2 or 3, characterized in that the polymer resin of the liner film (3) and / or the polymer resin of the composite tape (4) is a thermoplastic resin.

5. 5. The method according to claim 2, wherein the polymer resin of the liner film (3) and / or the composite tape (4) is a polyolefin-based polymer, a polyester-based polymer, a polyacetal-based polymer, a polyaryletherketone (PAEK)-based polymer, a polyamide-based polymer, a thermoplastic polyurethane-based polymer, polyphenylene sulfide (PPS), or a mixture thereof.

6. 6. The method according to claim 2, wherein the winding (S3a) of the liner film (3) and / or the winding (S3b) of the composite tape (4) is performed simultaneously with the heating (S3c) of the liner film (3) and / or the composite tape (4).

7. 7. The method according to claim 1, wherein shrinking (S5) the metal bosses (10a, 10b) is performed by immersing the metal bosses (10a, 10b) in dry ice made of solid carbon dioxide.

8. The metal bosses (10a, 10b) have necks (16a, 16b) that protrude outside the openings (14a, 14b) of the end fittings (11a, 11b), and after the step (S7) of expanding the metal bosses (10a, 10b), the method comprises the steps of: - inserting (S8) an annular sealing element (17) into the extraction orifice (7) in contact with the periphery of the neck (16a, 16b); 8. The method according to claim 1, comprising:

9. 9. A method according to claim 8, characterized in that the annular sealing element (17) is made of a polymeric resin, preferably a thermoplastic resin.

10. The metal bosses (10a, 10b) have necks (16a, 16b) that protrude outside the openings (14a, 14b) of the end fittings (11a, 11b), and the method, after expanding the metal bosses (S7), comprises the steps of: - forming a second fiber composite shell layer (5) on the first fiber composite shell layer (2) and on the annular sealing element (17) (S9), 10. The method according to any one of claims 8 to 9, characterized in that it comprises:

11. The forming (S9) of the second fiber composite shell layer (5) comprises the following steps: - winding (S9a) a composite tape (4) made of a composite material mixing fibers and polymer resin around the first fiber composite shell layer (2) and the annular sealing element (17); and - heating the composite tape (4) to co-solidate the first fiber composite shell layer (2) and the second fiber composite shell layer (5) (S9b); The method of claim 10, comprising:

12. 12. The method according to claim 11, characterized in that the polymer resins of the annular sealing element (17), the first fiber composite shell layer (2) and the second fiber composite shell layer (5) are the same.

13. 13. The method according to claim 11 or 12, characterized in that the polymer resin of the annular sealing element (17), the first fiber composite shell layer (2) and / or the second fiber composite shell layer (5) is a thermoplastic resin.

14. 14. The method according to claims 11 to 13, characterized in that the polymer resin of the annular sealing element (17), the first fiber composite shell layer (2) and / or the second fiber composite shell layer (5) is a polyolefin-based polymer, a polyester-based polymer, a polyacetal-based polymer, a polyaryletherketone (PAEK)-based polymer, a polyamide-based polymer, a thermoplastic polyurethane-based polymer, polyphenylene sulfide (PPS), or a mixture thereof.

15. 12. The method according to claim 2 or 11, characterized in that the fibers of the composite tape (4) comprise carbon fibers, glass fibers and / or basalt fibers.

16. A fiber composite tank (1) for containing a fluid, the product being obtained from the method according to any one of claims 1 to 15, a first fiber composite shell layer (2), - a metal boss (10a, 10b) having a base (12a, 12b) with an annular outer radial surface (13a, 13b); end fittings (11a, 11b) which are metal rings having openings (14a, 14b) surrounded by annular inner radial surfaces (15a, 15b); The present invention is characterized by comprising: A fiber composite tank (1), characterized in that the annular outer radial surfaces (13a, 13b) of the metal bosses (10a, 10b) are in sealing contact with the annular inner radial surfaces (15a, 15b) of the openings (14a, 14b) of the end fittings (11a, 11b).

17. 17. The fiber composite tank (1) according to claim 16, further comprising an annular seal (28) provided between the annular outer radial surfaces (13a, 13b) of the metal bosses (10a, 10b) and the annular inner radial surfaces (15a, 15b) of the end fittings (11a, 11b).

18. 18. The fiber composite tank (1) according to claim 17, characterized in that the annular seal (28) is an O-ring seal (281) or an injection seal (282) formed by injecting an elastomeric material, and the annular seal is accommodated in two opposing annular grooves (29, 30), one annular groove (30) being provided in the annular inner radial surface (15a, 15b) of the end fitting (11a, 11b) and one annular groove (29) being provided in the annular outer radial surface (13a, 13b) of the metal boss (10a, 10b).

Images