One-piece blade preform incorporating unidirectional fabric through-portions

Abstract

A blade fibre preform (200) for a turbomachine having three-dimensional or multi-layer weaving comprising, in one piece, a root preform part (230), a shank preform part (250) and an airfoil preform part (220), at least one lower platform preform part (240) and at least one upper platform preform part (260), the preform further comprising upstream and downstream wall preform parts (270, 280) formed from first to fourth unidirectional fabric portions (107, 108, 109, 110).

Description

[0001] Description

[0002] Title of the invention: One-piece blade preform incorporating through-flow unidirectional fabric portions

[0003] Technical Field

[0004] The present invention relates to the field of blades made of composite material comprising a fibrous reinforcement densified by a matrix. The field concerned is that of gas turbine blades for aeronautical engines or industrial turbines.

[0005] Prior art

[0006] The production of composite material blades for turbomachines has already been proposed.

[0007] Organic matrix composites (OMCs) and ceramic matrix composites (CMCs) replace metallic parts in certain parts of turbomachines. Their use contributes to optimizing aircraft performance, particularly by improving the efficiency of the turbomachine and reducing the overall mass of the turbomachine, significantly reducing harmful emissions to the environment (CO, CO2, NOx, etc.).

[0008] Document US 9,086,454 describes the manufacture of a turbomachine blade made of composite material comprising a fiber reinforcement densified by a matrix. More specifically, this method has the particularity that the fiber blank produced by three-dimensional weaving is shaped to obtain a fiber preform in a single piece having a first part forming a blade preform and blade root and at least a second part forming a blade platform preform. Thus, after densification of the preform, it is possible to obtain a blade made of composite material having a fiber reinforcement constituted by the preform and densified by the matrix, and forming a single piece with a platform provided with covering spoilers.The production of fiber reinforcement by three-dimensional weaving in a single piece has several advantages, including that of giving the blade very good mechanical properties, in particular very good resistance to delamination, and that of allowing the production of parts with complex geometries.

[0009] On a gas turbine blade, secondary sealing and aerodynamic functions are to be expected. In the lower part of the blade, i.e. near the blade root, these functions are provided by platforms connected to each other by walls. In the case of a blade made of composite material with fiber reinforcement produced by three-dimensional weaving in a single piece, the deployment of the platforms and walls during the shaping of the fiber blank (production of the blade preform) can prove difficult due to the limits of the deployability of three-dimensional woven textures and the problem of the triple point at the intersection of the walls and the blade root.

[0010] Another difficulty lies in the cutting of the fiber blank. Indeed, in addition to the trimming operation, certain local non-through cuts are necessary. These cuts are currently only mechanical, and significantly stress / deform the woven blanks. In addition, since the cuts are made manually, they are not very precise (1 to 2 mm) and have an irregular profile.

[0011] Statement of the invention

[0012] It is therefore desirable to be able to propose a solution for the production of blades in composite material from a three-dimensional weave which does not present the aforementioned drawbacks.

[0013] To this end, the present invention proposes a method for manufacturing a fiber preform for a turbomachine blade made of composite material, the method comprising:

[0014] - the formation of a fibrous blank by three-dimensional or multi-layer weaving between a plurality of layers of warp threads extending in a longitudinal direction corresponding to the longitudinal direction of the blade to be produced and a plurality of layers of weft threads in a transverse direction corresponding to the transverse direction of the blade to be produced, the fibrous blank comprising: - a first set of layers of warp and weft threads which are linked together, the first set extending in the longitudinal direction between first and second longitudinal ends, in the transverse direction between first and second transverse ends intended to form respectively a leading edge and a trailing edge of the blade, and in a thickness direction of the blank, between first and second faces intended to form respectively an intrados face and an extrados face of the blade,said first assembly forming a first part of the blank corresponding at least to a part of the blade,

[0015] - a second set of layers of warp and weft threads which are linked together at least locally to form a second part of the blank corresponding at least to a part of the lower blade platform preform,

[0016] - a third set of layers of warp and weft yarns which are bonded together at least locally to form a third part of the blank corresponding at least to a part of the upper blade platform preform, the yarns of the first part not being bonded to the yarns of the second and third parts, the fibrous blank further comprising on the side of the first face of the first part first and second portions of unidirectional fabric present respectively in the vicinity of the first and second transverse ends of the first part and on the side of the second face of said first part third and fourth portions of unidirectional fabric present respectively in the vicinity of the first and second transverse ends of the first part,the first to fourth portions of unidirectional fabric comprising non-woven warp yarns with weft yarns and each passing through the second and third portions of the blank,

[0017] - forming, from the fiber blank, a fiber preform of the blade to be manufactured comprising at least one blade blade preform portion formed from the first portion of the blank, at least one lower blade platform preform portion formed from the second portion of the blank, at least one upper blade platform preform portion formed from the third portion of the blank, and wall preform portions formed from the first to fourth portions of unidirectional fabric. The shaping of the platforms and walls is greatly facilitated by producing the walls from layers of unidirectional yarns held by two textile assemblies on either side intended to form the lower and outer platforms. It is thus possible to produce platforms, spoilers and walls in varied and complex shapes, and this from a fiber blank woven in a single piece.The stresses and tensions induced in the blank can be considerably reduced thanks to the relaxation provided by the presence of the unidirectional fabric portions.

[0018] Furthermore, the method of the invention makes it possible to avoid manual cutting operations when shaping the fiber blank.

[0019] According to a characteristic of the method of the invention, the first part of the blank is crossed by wires of the second part of the blank and by wires of the third part of the blank.

[0020] According to another characteristic of the method of the invention, the fiber blade preform further comprises a first upstream spoiler preform portion formed from the second portion of the blank and excess lengths of the first and third portions of unidirectional fabrics.

[0021] According to another characteristic of the method of the invention, the fiber blade preform further comprises a second upstream spoiler preform part formed from the third part of the blank and excess lengths of the first and third portions of unidirectional fabrics, a downstream spoiler preform part formed from the third part of the blank and excess lengths of the second and fourth portions of unidirectional fabrics.

[0022] According to another characteristic of the method of the invention, the first set of layers of warp and weft threads linked together forming the first part of the blank further corresponds to root and stilt preform parts, the formation of the fiber preform of the blade to be manufactured comprising root and stilt preform parts of the moving blade formed from the first part of the blank.

[0023] The invention also relates to a method for manufacturing a turbomachine blade made of composite material, the method comprising: - manufacturing a turbomachine blade preform according to the method for manufacturing a fiber blade preform,

[0024] - densification of the preform by a matrix to obtain a blade made of composite material having at least one blade, at least one lower platform, at least one upper platform and walls.

[0025] The invention also relates to a method for manufacturing a moving turbomachine blade made of composite material, the method comprising:

[0026] - the manufacture of a turbomachine mobile blade preform according to the manufacturing process of a fiber blade preform,

[0027] - densification of the preform by a matrix to obtain a mobile blade made of composite material having a foot, a stilt, a blade, at least one lower platform, at least one upper platform and walls.

[0028] The invention also relates to a fiber blade preform for a turbomachine having a three-dimensional or multi-layer weave comprising in a single piece at least one blade preform portion, at least one lower platform preform portion and at least one upper platform preform portion, the preform further comprising upstream and downstream wall preform portions formed from first to fourth portions of unidirectional fabric.

[0029] The invention also relates to a fibrous preform for a mobile blade for a turbomachine having a three-dimensional or multi-layer weave comprising in a single piece a root preform part, a stilt preform part and a blade preform part, at least one lower platform preform part and at least one upper platform preform part, the preform further comprising upstream and downstream wall preform parts formed from first to fourth portions of unidirectional fabric.

[0030] According to a characteristic of the preform of the invention, the latter further comprises a first upstream spoiler preform part comprising excess lengths of the first and third portions of unidirectional fabrics.

[0031] According to another characteristic of the preform of the invention, the latter further comprises a second upstream spoiler preform part comprising excess lengths of the first and third portions of unidirectional fabrics, a downstream spoiler preform part comprising excess lengths of the second and fourth portions of unidirectional fabrics.

[0032] According to another characteristic of the preform of the invention, the latter further comprises a foot preform part and a stilt preform part.

[0033] The invention further relates to a turbomachine blade made of composite material comprising a fiber reinforcement densified by a matrix, the blade comprising at least one blade, at least one lower platform, at least one upper platform and upstream and downstream walls, the fiber reinforcement comprising a fiber blade preform according to the invention.

[0034] The invention further relates to a turbomachine mobile blade made of composite material comprising a fiber reinforcement densified by a matrix, the blade comprising a root, a stilt, a blade, at least one lower platform, at least one upper platform and upstream and downstream walls, the fiber reinforcement comprising a fiber blade preform according to the invention.

[0035] The invention further relates to an aeronautical engine comprising a plurality of blades according to the invention.

[0036] The invention further relates to an aircraft comprising at least one engine according to the invention.

[0037] Brief description of the drawings

[0038] [Fig. 1 A and 1 B] Figures 1 A and 1 B are schematic perspective views of a moving blade made of composite material in accordance with one embodiment of the invention,

[0039] [Fig. 2A and 2B] Figures 2A and 2B illustrate very schematically an example of arrangement of three sets of layers of yarns and portions of unidirectional fabrics in a three-dimensional woven fiber blank intended for the production of a fiber preform for a blade such as that illustrated in Figures 1 A and 1 B, [Fig. 3A, 3B, 4A, 4B, 5A and 5B] Figures 3A, 3B, 4A, 4B, 5A and 5B illustrate successive steps of production of a fiber preform for a blade such as illustrated in Figures 1 A and 1 B.

[0040] Description of the embodiments

[0041] The invention is applicable to different types of turbomachine blades with integrated platforms. It is particularly applicable to fixed compressor blades, i.e. blades not comprising a root and a stilt. It is also applicable to moving compressor and turbine blades of different gas turbine bodies, for example a low pressure (LP) turbine wheel blade, such as that illustrated in FIGS. 1 A and 1 B.

[0042] The blade 10 of figures 1 A and 1 B comprises, in a manner well known per se, a blade 20, a root 30 formed by a part of greater thickness, for example with a bulb-shaped section, extended by a stilt 32, a lower platform 40 located close to the root 30 and provided with a first upstream covering spoiler 41, an upper platform 50 located between the lower platform 40 and the blade 20 and provided with a second upstream covering spoiler 51 and a downstream covering spoiler 52, and an upstream wall 60 and a downstream wall 70 present between the lower platform 40 and the upper platform 50.

[0043] The blade 20 extends in the longitudinal direction between the upper platform 50 and a longitudinal end 21 and has in cross section a curved profile of variable thickness between its leading edge 20a and its trailing edge 20b.

[0044] The longitudinal end 21 may in certain cases be provided with a heel, spoilers and lips as known per se (not shown in FIGS. 1 A and 1 B). The blade 10 is mounted on a turbine rotor (not shown) by engaging the root 30 in a correspondingly shaped housing arranged on the periphery of the rotor. The root 30 is extended by a lip 32 to connect to the internal (or lower) face 52 of the upper platform 50.

[0045] At its inner radial end, the blade 20 connects to the upper platform 50 on an outer (or upper) face 53 of the platform which delimits, on the inside, the gas flow vein in the turbine. In its upstream and downstream end portions (in the direction F of flow of the gas flow), the lower platform 40 is preceded by an upstream covering spoiler 41 while the upper platform 50 ends with an upstream covering spoiler 51. In the example illustrated, the upper platform 50 is inclined, generally forming a non-zero angle relative to the normal to the longitudinal direction of the blade. Depending on the desired profile of the inner surface of the gas flow vein, the angle could be zero, or the upper platform could have a generally non-rectilinear profile, for example curved.

[0046] Figures 2A and 2B show very schematically a fiber blank 100 from which a fiber blade preform can be shaped in order, after densification by a matrix and possible machining, to obtain a blade made of composite material with integrated platform and heel such as that illustrated by figures 1A and 1B.

[0047] The blank 100 comprises three parts 102, 104 and 106 obtained by three-dimensional weaving or multi-layer weaving, only the envelopes of these three parts being shown in FIGS. 2A and 2B. The part 102 is intended, after shaping, to constitute a part of a fiber blade preform corresponding to a blade, stilt and blade root preform. The part 104 is intended, after shaping, to constitute the parts of the fiber blade preform corresponding to lower blade platform and upstream blade spoiler preforms. As for the part 106, it is intended, after shaping, to constitute the parts of the fiber blade preform corresponding to upper blade platform, upstream spoiler and downstream blade spoiler preforms.

[0048] The three parts 102, 104 and 106 are in the form of fibrous strips extending generally in a longitudinal direction D Lcorresponding to the longitudinal direction of the blade to be produced. The part 102 has, in its part intended to form a blade preform, a variable thickness determined as a function of the profile thickness of the blade of the blade to be produced. In its part intended to form a root preform, the part 102 has an excess thickness 103 determined as a function of the thickness of the root of the blade to be produced. The part 102 extends, in a longitudinal direction DL, between first and second longitudinal ends 102c, 102d, in a transverse direction D T corresponding to the transverse direction of the blade between first and second transverse ends 102e, 102f intended to form respectively a leading edge and a trailing edge of the blade, and following a direction of thickness D E of the blank, between first and second faces 102a, 102b intended to form respectively an intrados face and an extrados face of the blade.

[0049] The rough portion 102 has a width chosen as a function of the length of the developed profile (flat) of the blade and the root of the blade to be produced while the rough portions 104 and 106 each have a width greater than I chosen as a function of the developed lengths of the lower and upper platforms of the blade to be produced. The rough portions 104 and 106 have substantially the same width and are each of substantially constant thickness determined as a function of the thicknesses of the platforms of the blade to be produced. The portions 104 and 106 each comprise a first portion 104a, 106a which extends along and in the vicinity of the first face 102a of the portion 102 and a second portion 104b, 106b which extends along and in the vicinity of the second face 102b of the portion 102.

[0050] The portions 104a and 104b of the blank portion 104 are connected by a connecting portion 140c which extends transversely with respect to the blank portion 102 at a location corresponding to that of the lower platform of the blade to be produced. The connecting portion 140c passes through the portion 102 in a direction substantially parallel to the normal to the longitudinal direction of the fiber blank. The portions 106a and 106b of the blank portion 106 are connected by a connecting portion 160c which extends transversely with respect to the blank portion 102 at a location corresponding to that of the upper platform of the blade to be produced. The connecting portion 160c passes through the strip at an angle α with respect to the normal to the longitudinal direction D L of the fibrous blank.

[0051] As described in more detail below, the blank portions 102, 104 and 106 are woven simultaneously by three-dimensional weaving, without bonding, on the one hand between the blank portion 102 and the portions 104a and 104b of the blank portion 104, and on the other hand between the blank portion 102 and the portions 106a and 106b of the blank portion 106 and by weaving a plurality of successive blanks 100 continuously in the longitudinal direction D L . No connection is also made between parts 104 and 106.

[0052] According to the invention, the fiber blank 100 further comprises, on the side of the first face 102a of the part 102 (of the first set of layers of yarns), first and second portions of unidirectional fabric 107 and 108 present respectively in the vicinity of the first and second transverse ends 102e and 102f of the part 102 (of the first set) (Figure 2A) and on the side of the second face 102b of the part 102 (of said first set) third and fourth portions of unidirectional fabric 109 and 110 present respectively in the vicinity of the first and second transverse ends 102e and 102f of the part 102 (of said first set) (Figure 2B).

[0053] The first to fourth unidirectional fabric portions 107, 108, 109 and 110 each comprise non-woven warp yarns with weft yarns. Each of the unidirectional fabric portions 107, 108, 109 and 110 passes through the portions of 104 and 106 at their connecting portion 140c, 160c.

[0054] Figures 3A, 3B, 4A, 4B, 5A to 5B show very schematically how a fiber preform having a shape close to that of the blade to be manufactured can be obtained from the fiber blank 100. The fiber part or strip 102 is cut at one end in the excess thickness 103 and at another opposite end to have a strip 120 of length corresponding to the longitudinal dimension of the blade to be manufactured with a swollen part 130 formed by a part of the excess thickness 103 and located at a location corresponding to the position of the root of the blade to be manufactured.

[0055] In addition, cutouts are made in the first and second parts 104a and 104b of the blank part 104 to leave sections 140a and 140b on either side of the connecting part 140c as shown in FIGS. 3A and 3B. Similarly, cutouts are made in the first and second parts 106a and 106b of the blank part 106 to leave sections 160a and 160b on either side of the connecting part 160c as shown in FIGS. 3A and 3B. The lengths of the sections 140a, 140b and 160a, 160b are determined as a function of the platform and heel lengths in the blade to be manufactured.

[0056] Cuts are also made in the first to fourth portions of unidirectional fabric 107, 108, 109 and 110. More specifically, a first cut is made in the portions of unidirectional fabric 107, 108, 109 and 110 at a determined distance below the connecting portion 140c so as to leave first overlengths 107a, 108a, 109a and 110a. A second cut is made in the portions of unidirectional fabric 107, 108, 109 and 110 at a determined distance above the connecting portion 160c so as to leave second overlengths 107c, 108c, 109c and 110c. The parts 107b, 108b, 109b and 110b of the unidirectional fabric portions 107, 108, 109 and 110 present between the sections 140a and 140b, on the one hand, and the sections 160a and 160b, on the other hand, are intended to form wall preform parts as explained below.

[0057] Due to the crossing, on the one hand between the part 102 and the parts 104a and 104b of the part 104, and on the other hand between the part 102 and the parts 106a and 106b of the part 106, the sections 140a, 140b, 160a and 160b can be folded perpendicular to the strip 102 without cutting any wires to form trays 140, 160, as shown in FIGS. 4A and 4B. The first overlengths 107a, 108a, 109a and 110a are folded onto the internal face 141 of the plate 140 (not shown in FIGS. 4A and 4B) while the second overlengths 107c, 108c, 109c and 110c are folded onto the external face 162 of the plate 160.

[0058] A fiber preform 200 of the blade to be manufactured is then obtained by molding with deformation of the blank portion 102 to reproduce the curved profile of the blade of the blade. The lower plate 140 is also deformed to reproduce a shape similar to that of the lower platform of the blade with an upstream covering spoiler. Similarly, the plate 160 is deformed to reproduce a shape similar to that of the upper platform of the blade with upstream and downstream covering spoilers as shown in FIGS. 5A and 5B. The parts 107b, and 108b of the unidirectional fabric portions 107 and 108 present between the lower plate 140 and the upper plate 160 are deformed to reproduce a shape similar to that of the upstream wall of the blade.The parts 109b and 110b of the unidirectional fabric portions 109 and 110 present between the lower plate 140 and the upper plate 160 are deformed to reproduce a shape similar to that of the downstream wall of the blade.

[0059] A preform 200 is thus obtained with a blade preform portion 220, a root preform portion 230, a stilt preform portion 250, a lower platform preform portion 240 with a first upstream spoiler preform portion 241, an upper platform preform portion 260 with a second upstream spoiler preform portion 261 and a downstream spoiler preform portion 262, an upstream wall preform portion 270 and a downstream wall preform portion 280. The fiber preform 200 is then densified. The densification of the fiber preform intended to form the fiber reinforcement of the blade to be manufactured consists of filling the porosity of the preform, in all or part of its volume, with the material constituting the matrix.This densification can be carried out in a manner known per se using the liquid process (CVL) or the gas process (CVI), or the ceramic charge injection process (Slurry Cast) or the silicon alloy impregnation process (Ml or RMI) or even using a sequence of one or more of these processes.

[0060] The wet-cure process involves impregnating the preform with a liquid composition containing a precursor to the matrix material. The precursor is usually in the form of a polymer, such as a high-performance epoxy resin, possibly diluted in a solvent. The preform is placed in a sealable mold with a housing shaped like the final molded blade. The mold is then closed and the liquid matrix precursor (e.g., a resin) is injected throughout the housing to impregnate the entire fiber portion of the preform.

[0061] The transformation of the precursor into a matrix, namely its polymerization, is carried out by heat treatment, generally by heating the mold, after elimination of any solvent and crosslinking of the polymer, the preform always being maintained in the mold having a shape corresponding to that of the part to be produced.

[0062] In the case of carbon or ceramic matrix formation, the heat treatment consists of pyrolyzing the precursor to transform the matrix into a carbon or ceramic matrix depending on the precursor used and the pyrolysis conditions. For example, liquid ceramic precursors, particularly SiC or SiCN, can be polycarbosilane (PCS) or polytitanocarbosilane (PTCS) or polysilazane (PSZ) resins, while liquid carbon precursors can be resins with a relatively high coke content, such as phenolic resins. Several consecutive cycles, from impregnation to heat treatment, can be carried out to achieve the desired degree of densification.

[0063] In the case of the formation of an organic matrix, the densification of the fiber preform can be carried out by the well-known transfer molding process known as RTM ("Resin Transfer Molding"). According to the RTM process, the fiber preform is placed in a mold having the external shape of the part to be produced. A thermosetting resin is injected into the internal space of the mold which includes the fiber preform. A pressure gradient is generally established in this internal space between the place where the resin is injected and the resin discharge orifices in order to control and optimize the impregnation of the preform by the resin.

[0064] Preform densification can also be achieved by polymer impregnation and pyrolysis (PI P), or by impregnation of a slip ("slurry cast"), containing for example SiC and organic binders, followed by infiltration with liquid silicon ("Melt infiltration").

[0065] The densification of the fiber preform can also be carried out, in a known manner, by gaseous means by chemical vapor infiltration of the matrix (CVI). The fiber preform corresponding to the fiber reinforcement of the blade to be produced is placed in a furnace into which a reaction gas phase is admitted. The pressure and temperature prevailing in the furnace and the composition of the gas phase are chosen so as to allow the diffusion of the gas phase within the porosity of the preform to form the matrix by deposition, at the heart of the material in contact with the fibers, of a solid material resulting from a decomposition of a constituent of the gas phase or a reaction between several constituents, unlike the pressure and temperature conditions specific to CVD ("Chemical Vapor Deposition") processes which exclusively lead to a deposition on the surface of the material.

[0066] The formation of a SiC matrix can be achieved with methyltrichlorosilane (MTS) yielding SiC by decomposition of MTS while a carbon matrix can be achieved with hydrocarbon gases such as methane and / or propane yielding carbon by cracking.

[0067] Densification combining liquid and gaseous methods can also be used to facilitate implementation, limit costs and manufacturing cycles while obtaining satisfactory characteristics for the intended use. The densification methods described above make it possible to produce, from the fibrous structure of the invention, mainly parts made of organic matrix composite (OMC), carbon matrix (C / C) and ceramic matrix (CMC) material.

[0068] In the case of producing a part in oxide / oxide composite material, the fibrous structure is impregnated with a slip loaded with refractory oxide particles. After removing the liquid phase of the slip, the preform thus obtained is subjected to a heat treatment in order to sinter the particles and obtain a refractory oxide matrix. The impregnation of the structure can be carried out with processes using a pressure gradient, such as injection molding processes known as "RTM" or submicron powder suction known as "APS".

[0069] After densification, the mobile blade 10 is obtained in composite material which, as illustrated in FIGS. 1 A and 1 B, comprises in its lower part a root 30 formed by the root preform part 230 of the fiber preform 200 which is extended by a stilt 32 formed by the stilt preform part 250 of the preform 200 and a blade or aerodynamic profile 20 formed by the blade preform part 220 of the preform 200. The blade 20 comprises a leading edge 20a and a trailing edge 20b corresponding respectively to the first and second transverse edges of the fiber preform 200.The blade 10 further comprises a lower platform 40 corresponding to the lower platform preform portion 240 of the preform 200, an upper platform 50 corresponding to the upper preform portion 260 of the preform 200, an upstream wall 60 corresponding to the upstream wall preform portion 270 of the preform 200, a first upstream covering spoiler 41 corresponding to the upstream first spoiler preform portion 241 of the preform 200, a downstream wall 70 corresponding to the downstream wall preform portion 280 of the preform 200, a second upstream covering spoiler 51 corresponding to the upstream second spoiler preform portion 261 of the preform 200 and a downstream covering spoiler 52 corresponding to the downstream spoiler preform portion 262 of the preform 200.

Claims

Claims

1. Method for manufacturing a fiber preform of a turbomachine blade made of composite material, the method comprising: - the formation of a fibrous blank (100) by three-dimensional or multi-layer weaving between a plurality of layers of warp threads extending in a longitudinal direction (D L ) corresponding to the longitudinal direction of the blade to be produced and a plurality of layers of weft threads following a transverse direction (D T ) corresponding to the transverse direction of the blade to be produced, the fiber blank comprising: - a first set of layers of warp and weft threads which are linked together, the first set extending, in the longitudinal direction (D L ), between first and second longitudinal ends, in the transverse direction (D T) between first and second transverse ends (102e, 102f) intended to form respectively a leading edge and a trailing edge of the blade, and following a thickness direction (D E ) of the blank, between first and second faces (102a, 102b) intended to form respectively an intrados face and an extrados face of the blade, said first assembly forming a first part (102) of the blank (100) corresponding at least to a part of the blade blade, - a second set of layers of warp and weft threads which are linked together at least locally to form a second part (104) of the blank corresponding at least to a part of the lower blade platform preform, - a third set of layers of warp and weft yarns which are bonded together at least locally to form a third part (106) of the blank corresponding at least to a part of the upper blade platform preform, the yarns of the first part (102) not being bonded to the yarns of the second and third parts (104, 106), the fibrous blank (100) further comprising on the side of the first face (102a) of the first part (102) first and second portions of unidirectional fabric (107, 108) present respectively in the vicinity of the first and second transverse ends (102e, 102f) of the first part and on the side of the second face (102b) of said first part of the third and fourth portions of unidirectional fabric (109, 110) present respectively in the vicinity of the first and second transverse ends of the first part, the first to fourth portions of unidirectional fabric (107, 108, 109, 110) comprising non-woven warp threads with weft threads and each passing through the second and third parts of the blank, - forming, from the fiber blank, a fiber preform (200) of the blade to be manufactured comprising at least one blade preform portion (220) of the blade formed from the first portion (102) of the blank (100), at least one lower blade platform preform portion (240) formed from the second portion (104) of the blank, at least one upper blade platform preform portion (260) formed from the third portion (106) of the blank, and wall preform portions (270, 280) formed from the first to fourth portions of unidirectional fabric (107, 108, 109, 110).

2. Method according to claim 1, in which the first part (102) of the blank (100) is crossed by wires of the second part (104) of the blank and by wires of the third part (106) of the blank.

3. The method of claim 1 or 2, wherein the fiber preform (200) further comprises a first upstream spoiler preform portion (240) formed from the second portion (102) of the blank (100) and overlengths (107a, 108a) of the first and third unidirectional fabric portions (107, 108).

4. The method of any one of claims 1 to 3, wherein the fiber preform (200) further comprises a second upstream spoiler preform portion (261) formed from the third portion (106) of the blank (100) and overlengths (107a, 108a) of the first and third unidirectional fabric portions (107, 108), a downstream spoiler preform portion (262) formed from the third portion (106) of the blank (100) and overlengths (109c, 110c) of the second and fourth unidirectional fabric portions (109, 110).

5. A method according to any one of claims 1 to 4, wherein the first set of layers of warp and weft yarns bonded together forming the first portion (102) of the blank (100) further corresponds to root and stilt preform portions, the formation of the fiber preform (200) of the blade to be manufactured comprising root (230) and stilt (250) preform portions of the moving blade formed from the first portion (102) of the blank (100).

6. Method for manufacturing a turbomachine blade (10) made of composite material, the method comprising: - the manufacture of a turbomachine blade preform (200) according to any one of claims 1 to 4, - densifying the preform by a matrix to obtain a blade (10) made of composite material having at least one blade (20), at least one lower platform (40), at least one upper platform (50) and walls (60, 70).

7. Method for manufacturing a moving blade (10) of a turbomachine made of composite material, the method comprising: - the manufacture of a preform (200) of a mobile turbomachine blade according to claim 5, - densifying the preform by a matrix to obtain a mobile blade (10) made of composite material having a foot (30), a stilt (32), at least one blade (20), at least one lower platform (40), at least one upper platform (50) and walls (60, 70).

8. A fiber blade preform (200) for a turbomachine having a three-dimensional or multi-layer weave comprising in a single piece a blade preform portion (220), at least one lower platform preform portion (240) and at least one upper platform preform portion (260), the preform further comprising upstream and downstream wall preform portions (270, 280) formed from first to fourth portions of unidirectional fabric (107, 108, 109, 110).

9. The preform of claim 8, further comprising a first upstream spoiler preform portion (241) comprising sur- lengths (107a, 108a) of the first and third portions of unidirectional fabrics (107, 108).

10. Preform according to claim 8 or 9, further comprising a second upstream spoiler preform portion (261) comprising overlengths (107c, 108c) of the first and third unidirectional fabric portions (107, 108), a downstream spoiler preform portion (262) comprising overlengths (109c, 110c) of the second and fourth unidirectional fabric portions (109, 110).

11. A preform according to any one of claims 8 to 10, further comprising a foot preform portion (230) and a stilt preform portion (250).

12. Turbomachine blade (10) made of composite material comprising a fibrous reinforcement densified by a matrix, the blade comprising at least one blade (20), at least one lower platform (40), at least one upper platform (50) and upstream and downstream walls (60, 70), the fibrous reinforcement comprising a fibrous blade preform according to any one of claims 8 to 10.

13. Movable blade (10) of a turbomachine made of composite material comprising a fibrous reinforcement densified by a matrix, the blade comprising a root (30), a stilt (32), a blade (20), at least one lower platform (40), at least one upper platform (50) and upstream and downstream walls (60, 70), the fibrous reinforcement comprising a fibrous blade preform according to claim 11.

14. An aeronautical engine comprising a plurality of blades according to claim 12 or a plurality of moving blades according to claim 13.

15. Aircraft comprising at least one engine according to claim 14.

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