METHOD FOR PRODUCEING A GUIDE SHAFTE FROM A COMPOSITE MATERIAL WITH INTEGRATED PLATFORMS AND FASTENING TABS, AND GUIDE SHAFTS PRODUCED BY THESE METHOD

Description

Technical Field

[0001] The present invention relates to the general field of fixed blades or stator for aeronautical gas turbine engine of the outlet guide vane or "OGV" type (for "outlet guide vane"). Previous technique

[0002] In the field of aircraft engines, guide vanes can be made of composite material that offers equivalent or greater strength than metal but with a lower overall mass. EP 3 186 486 describes a composite guide vane for a gas turbine engine, comprising a matrix-densified fiber reinforcement. The fiber reinforcement is formed in one piece by three-dimensional weaving with a blade and attachment lugs extending from the inner and outer radial ends of the blade to opposite lateral faces of said blade. WO 2013 / 079860 and 2016 / 174345 disclose, respectively, a fixed and a moving blade made of composite material.

[0003] A guide vane must simultaneously ensure the aerodynamic guidance of the air, a function for which geometry is paramount, and fulfill the structural function of the component, namely transferring the engine's forces between the hub and the connecting rods. To this end, the vane is equipped with internal and external platforms for flow delineation and force transmission.

[0004] In addition, the dawn must be able to perform these two main functions after having suffered external aggressions (post-bird ingestion residues, hail, erosion...).

[0005] Since the guide vanes are in the path of static loads, they are subjected to a wide variety of loads, including tension, compression, torsion, bending, and all possible combinations thereof. Therefore, it is crucial that the vane fixings ensure consistent behavior regardless of the direction and type of load.

[0006] Ear-type fasteners extend at an angle approximately perpendicular to the longitudinal axis of the blade, corresponding to the direction of the continuous warp threads. While composite parts exhibit very good mechanical properties in the fiber directions, these properties can be reduced in other directions. Furthermore, ear-type fasteners force the composite material to work in compression in directions that are not optimal for its properties.

[0007] Studies have been conducted to analyze the mechanical strength of the guide vanes, which are attached by tabs fixed to the blade. The results showed a systematic concentration of stresses at the fillets between the tabs and the blade, potentially leading to the initiation of cracks, matrix microcracks, or failures of the composite material at this location.

[0008] However, there is a need for a composite material output guide vane comprising integrated platforms which does not have critical areas in its attachment points with other engine elements. Description of the invention

[0009] To this end, the invention proposes a method for manufacturing a fixed turbomachine blade from composite material, the method comprising: the formation by three-dimensional or multi-layer weaving between a plurality of layers of warp yarns and a plurality of layers of weft yarns of a fibrous blank having a longitudinal axis corresponding to that of the blade of the blade to be produced, the fibrous blank extending between first and second longitudinal ends, the fibrous blank being separated in its thickness into first, second and third parts in two unbinding zones respectively present at the longitudinal ends of the fibrous blank, the first part being located between the second part and the third part to which it is connected by weaving outside of said unbinding zones, the formation, from the fibrous blank, of a preform of the blade to be produced, by unfolding, at the level of each longitudinal end and on either side of the first part, of the segments of the second part and the segments of the third part not connected to the first part,by shaping the unfolded segments of the second part and the unfolded segments of the third part to form preform parts for a blade platform to be manufactured at each longitudinal end of the fibrous blank, the segments of the first part not linked to the segments of the second and third parts extending along the longitudinal axis to form a preform part for a fixing tab of the part to be manufactured at each longitudinal end of the fibrous blank, , the densification of the preform by a matrix to obtain a fixed turbomachine blade in composite material having an integrated platform and a fixing lug at each longitudinal end aligned with the longitudinal axis of the blade, machining of the fixing lugs at each longitudinal end to form fixing holes.

[0010] With the process of the invention, a blade is obtained having mounting tabs aligned with the blade's longitudinal axis. This design eliminates any radius between the mounting tabs and the blade body. The blade thus operates at its mounting points only in tension and compression, that is, solely in the direction of the continuous warp threads of the blade's fibrous reinforcement. The resulting blade exhibits very good resistance to load transfer. Furthermore, the alignment of the mounting tabs with the blade body facilitates the integration of the necessary uncoupling mechanisms for platform formation.

[0011] According to a particular feature of the invention, warp threads present in the first part outside the unlinking zones are diverted in the second or third part into at least one unlinking zone. This increases the mechanical strength of the fibrous preform at the base of the unlinking points.

[0012] According to another particular feature of the invention, the first part has a greater thickness than the second and third parts. This reinforces the mechanical strength of the fixing brackets, which, unlike the platforms, are subjected to tensile and compressive forces.

[0013] The invention also relates to a method for manufacturing a fixed turbomachine blade from composite material, the method comprising: the formation by three-dimensional or multi-layer weaving between a plurality of warp yarn layers and a plurality of weft yarn layers of a fibrous blank having a longitudinal axis corresponding to that of the blade of the blade to be produced, the fibrous blank extending between first and second longitudinal ends, the fibrous blank being separated in its thickness into first, second and third parts in a debonding zone extending between its longitudinal ends, the first part being located between the second and third parts to which it is connected by weaving at the longitudinal ends of the fibrous blank so as to form two connecting portions, the cutting of the second and third parts to divide said second and third parts into two segments each, the formation, from the fibrous blank, of a preform of the blade to be produced, by unfolding,on either side of the first part, segments of the second part and segments of the third part not connected to the first part, by shaping the unfolded segments of the second part and the unfolded segments of the third part to form preform parts for a blade platform to be manufactured in the vicinity of each longitudinal end of the fibrous blank, the two connecting portions between the first, second and third parts extending along the longitudinal axis to form a preform part for a blade attachment lug to be manufactured at each longitudinal end of the fibrous blank, the densification of the preform by a matrix to obtain a composite material blade having an integrated platform and an attachment lug at each longitudinal end aligned with the longitudinal axis of the blade,machining of the mounting tabs at each longitudinal end to form mounting holes.

[0014] With the process of the invention, a blade is obtained having attachment tabs aligned with the blade's longitudinal axis. This design eliminates any radius between the attachment tabs and the blade body. The blade thus operates at its attachment points only in tension and compression, that is, solely in the direction of the continuous warp threads of the blade's fibrous reinforcement. The resulting blade exhibits very good resistance to load transfer, with the thickest portions of the blade corresponding to the attachment tabs. Furthermore, aligning the attachment tabs with the blade body facilitates the integration of the necessary decoupling mechanisms for platform formation.

[0015] According to a particular feature of the process of the invention, warp threads present in the first part in at least one bonding portion are deflected in the second or third part in the unbonding zone. This increases the mechanical strength of the fibrous preform at the bottom of the unbonds.

[0016] According to another particular feature of the invention, the first part has a greater thickness than the second and third parts. This reinforces the strength of the blade, which is the part of the blade most exposed to impacts with objects.

[0017] The invention further relates to a fixed turbomachine blade made of composite material comprising a fibrous reinforcement densified by a matrix, the blade having a blade extending along a longitudinal axis and two platforms integral with the blade and present respectively at the two longitudinal ends of the blade, such that the blade further comprises first and second fixing lugs having machined fixing holes and present respectively at each of the longitudinal ends of the blade and extending along the longitudinal axis, and in that the fibrous reinforcement has a three-dimensional or multi-layered weave, the fibrous reinforcement comprising a portion of blade preform dividing at each of its longitudinal ends into two half-parts of inner or outer platform preforms integral with the portion of blade preform and a portion of inner or outer fixing lug preform integral with the portion of blade preform,each preform portion of the internal or external fixing bracket extending along the longitudinal axis between the preform halves of the internal or external platform.

[0018] According to a particular feature of the process of the invention, warp threads present in the blade preform part of the fibrous reinforcement are deflected in a preform half of the inner or outer platforms.

[0019] According to another particular feature of the process of the invention, the preform part of the blade of the fibrous reinforcement has a thickness greater than the thickness of the preform halves of the inner or outer platforms.

[0020] The invention further relates to a fixed turbomachine blade made of composite material comprising a fibrous reinforcement densified by a matrix, the blade having a blade extending along a longitudinal axis and two platforms integral with the blade and present respectively at the two longitudinal ends of the blade, such that the blade further comprises first and second fixing lugs having machined fixing holes and present respectively at each of the longitudinal ends of the blade and extending along the longitudinal axis, and in that the fibrous reinforcement has a three-dimensional or multi-layered weave,The fibrous reinforcement comprises a blade preform portion joined at each of its longitudinal ends with two half-portions of inner or outer platform preforms integral with the blade preform portion, so as to form an inner or outer mounting lug preform portion integral with the blade preform portion, each inner or outer mounting lug preform portion extending along the longitudinal axis. According to a particular feature of the method of the invention, warp threads present in the inner or outer mounting lug portion of the fibrous reinforcement are deflected into an inner or outer platform preform half-portion.

[0021] According to another particular feature of the process of the invention, the preform part of the blade of the fibrous reinforcement has a thickness greater than the thickness of the preform halves of the inner or outer platforms. Brief description of the drawings

[0022] [ Fig. 1 ] There figure 1 is a schematic perspective view of a turbomachine blade according to one embodiment of the invention, [ Fig. 2 ] There figure 2 is a schematic plan view of a woven fibrous blank intended for the production of a fibrous preform for a blade of the type of that of the figure 1 , [ Fig. 3 ] There figure 3 is a side view of the draft of the figure 2 , [ Fig. 4 ] There figure 4 is a schematic, enlarged-scale view of the weaving plans of the draft of the figure 2 cross-sectional view according to plan IV-IV of the figure 2 , [ Fig. 5 ] There figure 5 is a schematic, enlarged-scale view of the weaving plans of the draft of the figure 2 cross-sectional view according to the VV plane of the figure 2 , [ Fig. 6 ] There figure 6 a schematic view showing the production of a blade preform from the fibrous blank of the figures 2 à 5 , [ Fig. 7 ] There figure 7 is a partial cross-sectional view of the blade preform of the figure 6 , [ Fig. 8 ] There figure 8 is a schematic perspective view of a turbomachine blade according to another embodiment of the invention, [ Fig. 9 ] There figure 9 is a schematic plan view of a woven fibrous blank intended for the production of a fibrous preform for a blade of the type of that of the figure 8 , [ Fig. 10 ] There figure 10 is a side view of the draft of the figure 9 , [ Fig. 11 ] There figure 11 is a schematic, enlarged-scale view of the weaving plans of the draft of the figure 9 cross-sectional view according to plan XI-XI of the figure 9 , [ Fig. 12 ] There figure 12 is a schematic, enlarged-scale view of the weaving plans of the draft of the figure 9 cross-sectional view according to the VV plane of the figure 9 , [ Fig. 13 ] There figure 13 a schematic view showing the production of a blade preform from the fibrous blank of the figures 9 à 12 , [ Fig. 14 ] There figure 14 is a partial cross-sectional view of the blade preform of the figure 13 . Description of the implementation methods

[0023] There figure 1 shows very schematically a blade 10, for example a fixed exit guide blade (OGV for " Outlet Guide Vane ") of a secondary flow straightener of an aeronautical turbomachine. The blade 10 comprises a blade 12, inner 14 and outer 16 platforms and inner 15 and outer 17 fixing lugs extending in the longitudinal direction of the blade 12 of the blade 10.

[0024] Throughout the text, the terms "inside" and "outside" are used in reference to the radial position relative to the axis of the turbomachine.

[0025] The outer face 14b of the platform 14 and the inner face 16a of the platform 16 are designed to define the gas flow path in the turbine after the blade 10 is mounted in a turbine housing. The inner mounting bracket 15 is designed to allow the blade 10 to be attached to a turbomachine hub via mounting holes 150, while the outer mounting bracket 17 is designed to allow the blade 10 to be attached to a turbomachine shell via mounting holes 170.

[0026] The blade 12 extends between the platforms 14 and 16 and the mounting brackets 15 and 17, to which it is attached. The mounting brackets 15 and 17 are solid elements without any cavity extending in the longitudinal direction of the blade 12.

[0027] Blade 10 is made of composite material. Its manufacture includes the formation of a fibrous preform having a shape corresponding to that of the blade and the densification of the preform by a matrix.

[0028] There figure 2 shows in plan a fibrous rough 101 from which a fibrous preform of the blade 10 can be formed.

[0029] The blank 101 is obtained from a strip 100 woven by three-dimensional (3D) or multi-layer weaving, the strip 100 generally extending in a direction D corresponding to the longitudinal direction of the blade to be manufactured. The weaving is carried out, for example, with warp threads extending in direction D, it being noted that weaving with weft threads extending in this direction is also possible. A plurality of blanks 101 can be woven one after the other in direction D. It is also possible to weave several parallel rows of blanks 101 simultaneously.

[0030] In the method of implementation of figures 2 à 5 A blank 101 extending along a longitudinal axis X comprises, within its thickness and at each of its ends 101a and 101b, a first part 102, 112, a second part 104, 114, and a third part 106, 116. Part 102 is located between part 104 and part 106. Part 102 is connected to parts 104 and 106 by 3D weaving in a zone 120 intended to form the blade of the turbine and is detached from parts 104 and 106 at a detachment zone 103 comprising a first detachment 103a between part 102 and part 104 and a second detachment 103b between part 102 and part 106. The detachments 103a, 103b extend across the entire width of the blank 101 (dimension in the weft direction) from the end 101a of the blank 101 to the unbundling points 103c and 103d. The unbundling points 103c and 103d extend between the longitudinal edges 101c and 101d of the blank 101 along the weft direction.

[0031] Part 112 is located between part 114 and part 116 and is linked to parts 114 and 116 by 3D weaving in the area 120 intended to form the blade of the blade and detached from parts 114 and 116 at the level of a detachment zone 105 comprising a first detachment 105a between part 112 and part 114 and a second detachment 105b between part 112 and part 116. The detachments 105a, 105b extend over the entire width of the blank 101 from the end 101b of the blank 101 to detachment bottoms 105c and 105d. The debonding bases 105c and 105d extend between the longitudinal edges 101c and 101d of the blank 101.

[0032] In a well-known way, a debonding is made between two layers of warp yarns by omitting to pass a weft yarn through the debonding zone to link yarns of warp layers located on either side of the debonding.

[0033] The plans of figures 4 And 5show an example of 3D weaving with interlock weave and 105a and 105b unlinks, the 103a and 103b unlinks being obtained in the same way as the 105a and 105b unlinks. On the figure 5 The unlinkings are represented by dashes. Part 112 comprises a plurality of warp yarn layers (8 in the illustrated example) which are linked by 3D weaving. Parts 114 and 116 each comprise a plurality of warp yarn layers (4 in the illustrated example) which are linked together by 3D weaving. Between the unlinking zone 103 delimited by the unlinking grounds 103c and 103d and the unlinking zone 105 delimited by the unlinking grounds 105c and 105d, the warp yarn layers of parts 102, 112, 104, 114 and 106, 116 are, in the illustrated example, all linked together ( figure 4 ).

[0034] After weaving, a fibrous preform 110 is formed from the blank 101. More precisely, segment 120a, located in the center of preform 110, corresponds to a portion of the blade preform. Segments 104a, 114a, 106a, and 116a of parts 104, 106, 114, and 116, which are not connected to parts 102 and 112 and are present at the longitudinal ends of segment 120a, are unfolded or deployed as shown in the figure. figure 6 in order to form each of the preform halves for platforms 14, 16, segments 104a, 114a being adjacent to the debonds 103a, 105a and segments 106a, 116a being adjacent to the debonds 103b, 105b. The unfoldings are carried out at the level of the debond bottoms.

[0035] According to the invention, segments 102a and 112a intended to form respectively a preform part of the inner fixing tab and a preform part of the outer fixing tab are left in their position parallel to the longitudinal direction X of the blank.

[0036] This forms a fibrous reinforcement for the blade 10 to be produced which includes a part of blade preform 120a dividing at each of its longitudinal ends into two half-parts of inner or outer platform preforms 104a, 106a and 114a, 116a attached to the part of blade preform and a part of inner or outer fixing lug preform 102a, 112a attached to the part of blade preform.

[0037] The fibrous preform 110 of the blade to be manufactured is then placed in a shaping tool to obtain the desired blade profile and the desired shapes for the platforms and fixing tabs.

[0038] A blade made of ceramic matrix composite (CMC) material such as that of the figure 1 can be manufactured in the following way.

[0039] A fibrous strip 100 is woven by three-dimensional weaving, comprising a plurality of fibrous blanks 101 oriented, for example, in the warp direction, with unbinding zones, as shown in the figure 2 Ceramic yarns, particularly silicon carbide (SiC) yarns, such as those supplied under the name "Nicalon" by the Japanese company Nippon Carbon, can be used for weaving. Other ceramic yarns are also suitable, including refractory oxide yarns, such as alumina (Al₂O₃) yarns, especially for oxide / oxide CMC materials (fibrous reinforcement fibers and refractory oxide matrix). Carbon yarns could also be used for a carbon fiber-reinforced CMC material.

[0040] As is known, the fibrous tape can be treated to remove the sizing present on the fibers and the presence of oxide on the surface of the fibers.

[0041] Also known is the application of a thin, debrittle interphase coating layer to the fibers of the fiber strip by chemical vapor infiltration (CVI). Examples of interphase materials include pyrolytic carbon (PyC), boron nitride (BN), and boron-doped carbon (BC). The thickness of the resulting layer is typically between 10 and 100 nanometers to maintain the deformation capacity of the fiber blanks.

[0042] The fibrous strip is then impregnated with a consolidation composition, typically a carbon precursor resin or a ceramic precursor resin, possibly diluted in a solvent. After drying, the individual fibrous blanks are cut. Each blank is shaped (as illustrated by the figure 6 ) and placed in a tooling for shaping the preform parts of the blade, inner and outer platforms and inner and outer fixing lugs.

[0043] Next, the resin is crosslinked and then pyrolyzed after removing the preform from the forming tooling to obtain a blade preform consolidated by the pyrolysis residue. The amount of consolidation resin is chosen to be sufficient but not excessive so that the pyrolysis residue binds the preform fibers, allowing it to be manipulated while retaining its shape without the assistance of tooling.

[0044] A second layer of debriding interphase coating can be formed by CVI, for example in PyC, BN or BC. The fabrication of a two-layer interphase coating before and after consolidation is described in document EP 2 154 119.

[0045] A ceramic matrix densification of the consolidated preform is then carried out, for example by CVI. The matrix can be SiC or a self-healing matrix comprising matrix phases of pyrolytic carbon PyC, boron carbide B4C, or a Si-BC ternary system, as described in particular in US documents 5,246,756 and US 5,965,266. Other types of ceramic matrix can be considered, including refractory oxide matrices, for example alumina, especially for oxide / oxide CMC materials.

[0046] The blade can also be manufactured from organic matrix composite material (OMC) (thermoplastic or thermosetting with a fibrous preform of any type). In this case, the densification of the fibrous preform is achieved using a known liquid-based process.

[0047] The liquid process involves impregnating the fibrous preform with a resin. The preform is placed in a mold that can be sealed tightly, with a cavity shaped like the final molded part. The resin, for example a thermoplastic or thermosetting resin, is then injected into the entire cavity to impregnate all the fibrous material of the preform.

[0048] Polymerization is achieved through heat treatment (generally by heating the mold). Since the preform remains within the mold, it retains the shape of the final part. The organic matrix can be obtained, in particular, from epoxy resins.

[0049] Once the preform is densified by the matrix, a blade is obtained whose geometry corresponds to the final blade 10 of the figure 1 . The inner fixing tab is then machined to form the fixing holes 150 and the outer fixing tab to form the fixing holes 170.

[0050] According to one aspect of the invention, the first parts 102, 112 have a thickness e 1 greater than the thickness e 2 of the second parts 104, 114 and the thickness e 3 of the third parts 106, 116 ( figure 3 ). In the example illustrated on the figures 4 And 5The second and third parts, 114 and 116, each comprise 4 layers of warp yarns, while the first part, 112, comprises 8 layers of warp yarns. The same applies to the first, second, and third parts, 102, 104, and 106, which are not shown in the diagrams. figures 4 And 5 .

[0051] The path of the warp threads in the fibrous preform can be straight, that is, the warp threads do not cross and the same warp threads remain present in the first, second, and third parts 102, 104, and 106 outside and in the unbinding zones. According to an alternative embodiment illustrated in the figure 7 Some warp threads present in the first section 112 outside the unlinking zone 105, here warp threads C1 and C2, are deflected into the second and third sections 114 and 116 at the unlinking zone 105. Warp threads present in the second and third sections 114 and 116 outside the unlinking zone 105, here warp threads C3 and C4, can also be deflected into the first section 112 at the unlinking zone 105. This increases the mechanical strength of the fibrous preform at the bottom of the unlinking zones 105c and 105d. The same can be true for warp threads from the first, second, and third sections 102, 104, and 106, which are not shown in the diagram. figure 7 .

[0052] There figure 8 schematically shows a blade 20 according to another embodiment of the invention. The blade 20, for example a fixed outfeed guide blade (OGV for " Outlet Guide Vane " of a secondary flow straightener of an aeronautical turbomachine, a blade 22, inner platform 24 and outer platform 26 and inner mounting lugs 25 and outer platform 27 extending in the longitudinal direction of the blade 22 of the blade 20. The outer face 24b of the platform 24 and the inner face 26a of the platform 26 are intended to delimit the gas flow path in the turbine after mounting the blade 20 in a turbine casing. The inner mounting bracket 25 is intended to allow the blade 20 to be fixed to a hub of the turbomachine via mounting holes 250 while the outer mounting bracket 27 is intended to allow the blade 20 to be fixed to a ferrule of the turbomachine via mounting holes 270. The blade 22 extends between the platforms 24 and 26 and the mounting brackets 25 and 27, to which it is attached.The fixing lugs 25 and 27 are solid elements without a cavity extending in the longitudinal direction of the blade 12.

[0053] The blade 20 is made of composite material. Its manufacture includes the formation of a fibrous preform having a shape corresponding to that of the blade and the densification of the preform by a matrix.

[0054] There figure 9 shows in plan a fibrous rough 201 from which a fibrous preform of the blade 20 can be formed.

[0055] The blank 201 is obtained from a strip 200 woven by three-dimensional (3D) or multi-layer weaving, the strip 200 generally extending in a direction D corresponding to the longitudinal direction of the blade to be manufactured. The weaving is carried out, for example, with warp threads extending in direction D, it being noted that weaving with weft threads extending in this direction is also possible. A plurality of blanks 201 can be woven one after the other in direction D. It is also possible to weave several parallel rows of blanks 201 simultaneously.

[0056] In the method of implementation of figures 10 à 12 A blank 201 extending along a longitudinal axis X comprises, within its thickness and at each of its ends 201a and 201b, a first part 202, 212, a second part 204, 214, and a third part 206, 216. Part 202 is located between part 204 and part 206. Part 202 is connected to parts 204 and 206 by 3D weaving in a connection zone or portion 220 intended to form the inner attachment tab of the blade and detached from parts 204 and 206 at a detachment zone 203 comprising a first detachment 203a between part 102 and part 104 and a second detachment 203b between part 202 and part 206. The detachments 203a and 203b extend across the entire width of the blank 201 (dimension in the frame direction) between the unbundling grounds 203c and 203d and unbundling grounds 203e and 203f. The unbundling grounds 203c, 203d, 203e and 203f extend between the longitudinal edges 201c and 201d of the blank 201 along the frame direction.

[0057] Part 212 is located between part 214 and part 216 and is linked to parts 214 and 216 by 3D weaving in a linking zone or portion 221 intended to form the outer fixing lug of the blade and detached from parts 214 and 216 at the level of the detachment zone 203 comprising the first detachment 203a between part 212 and part 214 and the second detachment 203b between part 212 and part 216.

[0058] In a well-known way, a debonding is made between two layers of warp yarns by omitting to pass a weft yarn through the debonding zone to link yarns of warp layers located on either side of the debonding.

[0059] The plans of figures 11 And 12 show an example of 3D weaving with interlock weave and 203a and 203b unbindings. On the figure 12 The unlinkings are represented by dashes. Part 202 comprises a plurality of warp yarn layers (8 in the illustrated example) that are linked by 3D weaving. Parts 204 and 206 each comprise a plurality of warp yarn layers (4 in the illustrated example) that are linked together by 3D weaving. In the linking portion 220, the warp yarn layers of parts 203, 204, and 206 are, in the illustrated example, all linked together ( figure 11 ). The same applies to parts 212, 214 and 216 in the connecting section 221.

[0060] After weaving, a fibrous preform 210 is formed from the blank 201. More precisely, parts 204 and 214 are first separated from parts 206 and 216, which are present in the unbinding zone 203, by making cuts 207a and 207b respectively ( figure 10 ). Once parts 204, 214, 206, and 216 are released, segments 204a, 214a, 206a, and 216a of parts 204, 206, 214, and 216 not linked to parts 202 and 212 are unfolded or deployed as shown in the figure 13 in order to form each of the preform halves for platforms 24, 26. The unfoldings are carried out at the level of the unbundling points. The segment located in the center of preform 210 corresponds to a blade preform section.

[0061] According to the invention, segments 202a and 212a intended to form respectively a preform part of the inner fixing tab and a preform part of the outer fixing tab are left in their position parallel to the longitudinal direction X of the blank.

[0062] This forms a fibrous reinforcement for the blade 20 to be produced which includes a part of the blade preform joining at each of its longitudinal ends with two half-parts of inner or outer platform preforms 204a, 206a; 214a, 216a attached to the part of the blade preform so as to form a part of the inner or outer fixing lug preform 202a; 212a attached to the part of the blade preform.

[0063] The 210 fibrous preform of the blade to be manufactured is then placed in a shaping tool to obtain the desired blade profile and the desired shapes for the platforms and fixing lugs.

[0064] A blade made of ceramic matrix composite (CMC) material such as that of the figure 8 can be manufactured in the manner already described previously for the dawn of the figure 1 and is therefore not repeated here again for the sake of simplicity.

[0065] Once the preform is densified by the matrix, a blade is obtained whose geometry corresponds to the final blade 20 of the figure 8 . The inner fixing tab is then machined to form the fixing holes 250 and the outer fixing tab to form the fixing holes 270.

[0066] According to one aspect of the invention, the first parts 202, 212 have a thickness e5 greater than the thickness e6 of the second parts 204, 214 and the thickness e7 of the third parts 206, 216. In the example illustrated on the figures 11 And 12 The second and third parts, 214 and 216, each comprise 4 layers of warp yarns, while the first part, 212, comprises 8 layers of warp yarns. The same applies to the first, second, and third parts, 202, 204, and 206, which are not shown in the diagrams. figures 11 And 12 .

[0067] As with the previously described fibrous preform of blade 10, the path of the warp threads in the fibrous preform can be straight, meaning that the warp threads do not cross and the same warp threads remain present in the first, second, and third parts 202, 204, and 206 outside and within the unbinding zones. According to an alternative embodiment illustrated in the figure 14 Some warp threads present in the first section 202, outside the unlinking zone 203—here, warp threads C11 and C12—are deflected into the second and third sections 204 and 206 at the unlinking zone 203. Warp threads present in the second and third sections 204 and 206, outside the unlinking zone 203—here, warp threads C13 and C14—can also be deflected into the first section 202 at the unlinking portion 220. This increases the mechanical strength of the fibrous preform at the bottom of the unlinkings 203c and 203d. The same can be true for warp threads from the first, second, and third sections 212, 214, and 216, which are not shown in the diagram. figure 14 .

Claims

1. A method for manufacturing a fixed turbomachine vane (10) made of composite material, the method including: - forming, by three-dimensional or multilayer weaving between a plurality of warp yarn layers and a plurality of weft yarn layers, a fiber blank (101) having a longitudinal axis (X) corresponding to that of the blade (12) of the vane (10) to be produced, the fiber blank extending between first and second longitudinal ends (101a, 101b), the fiber blank being separated across its thickness into first, second and third parts (102, 104, 106 ; 112, 114, 116) in two non-interlinked areas (103, 105) respectively present at the longitudinal ends of the fiber blank, the first part (102 ; 112) being located between the second part and the third part (104, 106 ; 114, 116) to which it is connected by weaving outside said non-interlinked areas (103, 105), - forming, from the fiber blank, (101), a preform (110) of the vane to be produced, by unfolding, at each longitudinal end and on either side of the first part (102, 112), the segments (104a, 114a) of the second part and the segments (106a, 116a) of the third part not interlinked with the first part, and by shaping the unfolded segments (104a, 114a) of the second part and the unfolded segments (106a, 116a) of the third part to form preform parts for a platform (14 ; 16) of the vane to be manufactured (10) at each longitudinal end of the fiber blank, the segments (102a, 112a) of the first part not interlinked with the segments of the second and third parts (104a, 114a, 106a, 116a), extending along the longitudinal axis (X) to form a preform part for a tab (15 ; 17) for attaching the part (10) to be manufactured at each longitudinal end of the fiber blank, - densifying the preform by a matrix to obtain a fixed turbomachine vane (10) made of composite material having an incorporated platform (14 ; 16) and an attaching tab (15 ; 17) at each longitudinal end aligned with the longitudinal axis of the vane, - machining attaching tabs at each longitudinal end to form attaching holes.

2. The method as claimed in claim 1, wherein warp yarns (C1, C2 present in the first part (112) outside the non-interlinked areas (103, 105) are diverted in the second or third part (114 ; 112) into at least one non-interlinked area.

3. The method as claimed in claim 1 or 2, wherein the first part (102 ; 112) has a thickness (e1) greater than the thickness (e2 ; e3) of the second and third parts.

4. A method for manufacturing a fixed turbomachine vane (20) made of composite material, the method including: - forming, by three-dimensional or multilayer weaving between a plurality of warp yarn layers and a plurality of weft yarn layers, a fiber blank (201) having a longitudinal axis (X) corresponding to that of the blade (22) of the vane (20) to be produced, the fiber blank extending between first and second longitudinal ends (201a, 201b), the fiber blank being separated across its thickness into first, second and third parts (202, 204, 206 ; 212, 214, 216) in a non-interlinked area (203) extending between its longitudinal ends, the first part (202 ; 212) being located between the second part and the third part (204, 206 ; 214, 216) to which it is connected by weaving at the longitudinal ends of the fiber blank in such a way as to form two interlinking portions (220, 221), - cutting out the second and third parts (204, 206, 214, 216) to divide said second and third parts into two segments each (204a, 214a ; 206a, 216a), - forming, from the fiber blank (201), a preform (210) of the vane to be produced, by unfolding, on either side of the first part (202 ; 212), the segments (204a, 214a) of the second part and the segments (206a ; 216a) of the third part not interlinked with the first part, and by shaping the unfolded segments (204a, 214a) of the second part and unfolded segments (206a, 216a) of the third part to form preform parts for a platform (24 ; 26) of the vane to be manufactured (20) in the vicinity of each longitudinal end of the fiber blank, the two interlinking portions (220, 221) between the first, second and third parts extending along the longitudinal axis (X) to form a preform part for an attaching tab (25 ; 27) of the vane to be manufactured (20) at each longitudinal end of the fiber blank, - densifying the preform by a matrix to obtain a vane (20) made of composite material having an incorporated platform (24 ; 26) and an attaching tab at each longitudinal end aligned with the longitudinal axis of the vane, - machining attaching tabs at each longitudinal end to form attaching holes..

5. The method as claimed in claim 4, wherein warp yarns (C11, C12 present in the first part (212) in at least one interlinking portion are diverted in the second or third part (214 ; 216) into the non-interlinked area.

6. The method as claimed in claim 4 or 5, wherein the first part (202 ; 212) has a thickness (e5) greater than the thickness (e6 ; e7) of the second and third parts.

7. A fixed turbomachine vane (10) made of composite material comprising a matrix-densified fiber reinforcement, the vane having a blade (12) extending along a longitudinal axis (X) and two platforms (14 ; 16) secured to the blade and respectively present at the two longitudinal ends of the vane, so that the vane further comprises first and second attaching tabs (15, 17) having attaching holes respectively present at each of the longitudinal ends of the vane and extending along the longitudinal axis (X) and in that the fiber reinforcement has a three-dimensional or multilayer weave, the fiber reinforcement comprising a blade preform part (120a) dividing at each of its longitudinal ends into two inner or outer platform preform half-parts (104a, 106a ; 114a, 116a) secured to the blade preform part and an inner or outer attaching tab preform part (102a ; 112a) secured to the blade preform part, each inner or outer attaching tab preform part extending along the longitudinal axis between the inner or outer platform preform half-parts.

8. The vane as claimed in claim 7, wherein warp yarns (C1, C2 are diverted into an inner or outer platform preform half-part.

9. The vane as claimed in claim 7 or 8, wherein the blade preform part (120a) of the fiber reinforcement has a thickness (e1) greater than the thickness (e2 ; e3) of the inner or outer platform preform half-parts (104a, 106a ; 114a, 116a).

10. A fixed turbomachine vane (20) made of composite material comprising a matrix-densified fiber reinforcement, the vane having a blade (22) extending in a longitudinal axis and two platforms (24 ; 26) secured to the blade and respectively present at the two longitudinal ends of the vane, so that the vane further comprises first and second attaching tabs (25, 27) having attaching holes respectively present at each of the longitudinal ends of the vane and extending along the longitudinal axis (X) and in that the fiber reinforcement has a three-dimensional weave, the fiber reinforcement comprising a blade preform part (220a) meeting again at each of its longitudinal ends with two inner or outer platform preform half-parts (204a, 206a ; 214a, 216a) secured to the blade preform part in such a way as to form an inner or outer attaching tab preform part (202a ; 212a) secured to the blade preform part, each inner or outer attaching tab preform part extending along the longitudinal axis.

11. The vane as claimed in claim 10, wherein warp yarns (C11, C12 present in the inner or outer attaching tab part of the fiber reinforcement are diverted into an inner or outer platform preform half-part.

12. The vane as claimed in claim 10 or 11, wherein the blade preform part (220a) of the fiber reinforcement has a thickness (e4) greater than the thickness (e5 ; e6) of the inner or outer platform preform half-parts (204a, 206a ; 214a, 216a).