Manufacturing process for a turbine blade made of composite material optimizing the distribution of warp yarn layers

Abstract

A method for manufacturing a turbine blade from composite material that optimizes the distribution of warp yarn layers. A method for manufacturing a turbomachine blade from composite material comprises: - the three-dimensional weaving of a fibrous blank (301). The fibrous blank has a first portion (P1) separated by unbinding (304) into a first part (302) present on a first face (301e) of the fibrous blank and a second part (303). The fibrous blank (301) further comprises a second portion (P2) separated by unbinding (307) into a third part (305) and a fourth part (306) present on a second face (301f) of the fibrous blank (301).- the formation, from the fibrous blank (301), of a fibrous preform of the blade to be produced, by unfolding and shaping the first part (302) and a segment (3061) of the fourth part (306) to form respectively the first and second parts of the platform preform, the second part (303) forming a part of the foot preform and the third part (305) forming at least one part of the blade preform, - the densification of the preform by a matrix to obtain a blade made of composite material having at least one foot, an integrated platform and a blade. Figure for the abstract: Fig. 4.

Description

Title of the invention: Method for manufacturing a turbine blade from composite material optimizing the distribution of warp yarn layers. Technical field

[0001] The invention relates to turbine or turbomachine compressor blades, the blades being made of fiber-reinforced composite material densified by a matrix.

[0002] The field concerned is that of gas turbines for aeronautical engines or for industrial turbines. Previous technique

[0003] One application of the invention is the production of blades made of ceramic matrix composite (CMC) material, which exhibit good mechanical properties making them suitable for use as structural elements and advantageously retaining these properties at high temperatures. Due to their superior resistance to high temperatures, CMC materials can be used at elevated temperatures. In the field of aircraft engines, CMC materials allow for higher temperatures to which parts are subjected, thereby improving engine efficiency and reducing fuel consumption. Furthermore, their use contributes to optimizing the performance of turbomachinery, particularly by reducing the overall mass of the turbomachine, which further contributes to lower fuel consumption and thus to a significant reduction in pollutant emissions.

[0004] The production of blades in composite material for turbomachinery has already been proposed, the fibrous reinforcement being obtained in particular from carbon or ceramic yarns and the matrix being in ceramic material or in organic material or in carbon.

[0005] US patent 2024 / 093612 describes a method for manufacturing a turbomachine blade comprising:

[0006] - the formation by three-dimensional or multi-layer weaving of a fibrous blank separated in its thickness into first, second and third parts by unlinking, the first part being located between the second and third parts to which it is connected by weaving outside of unlinking zones,

[0007] - the formation of preform parts of a platform at each level longitudinal end of the fibrous blank by unfolding of the second and third parts,

[0008] - the densification of the preform to obtain a fixed turbomachine blade in composite material having an integrated platform.

[0009] With this type of manufacturing process, the added features, such as platform, low wall, spoiler, etc., are created by symmetrically removing layers of warp yarns either from the lower part of the blade intended to form the blade foot or from the middle part intended to form the blade blade. When it is desired to retain as much textile material as possible at the foot, the layers of warp yarns are taken from a portion of the fibrous texture intended to form the blade blade. In this case, the number of warp yarns available to form the blade blade is limited, or even insufficient.

[0010] There is, therefore, a need to manufacture blades from composite material which allows greater flexibility in the removal of layers of warp yarns used to make functional elements compared to the main part of the blade intended to form the blade and the blade foot. Description of the invention

[0011] To this end, the invention proposes a method for manufacturing a turbomachine blade from composite material, the method comprising:

[0012] - the formation by three-dimensional or multilayer weaving between a plurality of layers of warp yarns and a plurality of layers of weft yarns of a fibrous blank, the fibrous blank extending in a longitudinal direction between a lower extremity and an upper extremity, in a lateral direction between a first edge and a second edge, and in a thickness direction perpendicular to the longitudinal and transverse directions between a first face and a second face, the fibrous blank comprising a first portion extending in the longitudinal direction from the lower extremity of the fibrous blank to a first intermediate position distant from the lower extremity of the fibrous blank, the fibrous blank being separated by unbinding in said first portion and in the thickness direction of said fibrous blank into a first part present on a first face of the fibrous blank and a second part,the first part comprising a number of warp yarn layers less than the number of warp yarn layers of the second part, the fibrous blank comprising a second portion extending along the longitudinal direction from a second intermediate position located above or at the same level as the first intermediate position and up to a third intermediate position distant from the second intermediate position and set back from the upper end of the fibrous blank, the fibrous blank being separated by unbinding in said second portion and along the thickness direction of said fibrous blank into a third, part and a fourth part present on a second face of the fibrous blank, the third part comprising a number of warp yarn layers greater than the number of warp yarn layers of the fourth part,

[0013] - the formation, from the fibrous blank, of a preform of the blade to be produced, by deployment and shaping of the first part and at least a first segment of the fourth part to form respectively the first and second parts of the platform preform, the second part forming a part of the foot preform and the third part forming at least one part of the blade preform,

[0014] - the densification of the preform by a matrix to obtain a blade made of material composite having at least one foot, an integrated platform and a blade.

[0015] With the process of the invention, the first part of the fibrous blank intended to form the first part of the blade platform preform to be produced is formed in the first portion of said blank, while the fourth part intended to form the second part of the blade platform preform to be produced is formed in the second portion located above the first portion along the longitudinal direction. Thus, the warp yarn layers of the fibrous blank used to form the platform preform portion are taken from two portions of said blank offset along its longitudinal direction. Consequently, unlike the prior art where the warp yarn layers used to form the two platform preform portions are taken symmetrically (i.e.extending at the same level on each side of the blank along the longitudinal direction) in the same portion located above a portion intended to form the foot preform, the manufacturing process of the invention makes it possible, by means of asymmetrically taking layers of warp yarns from two portions of the blank offset along the longitudinal direction, to maintain a greater number of warp yarn layers in the parts of the blank intended to form the blade of the blade to be produced. The process of the invention also makes it possible to adjust the number of warp yarn layers used in the second part of the fibrous blank intended to form the foot preform and thus to control the fiber content in the foot of the blade to be produced.

[0016] According to a particular feature of the process of the invention, the number of warp yarn layers in the first and second parts of the fiber blank is equal to the number of warp yarn layers in the third and fourth parts of said fiber blank. This simplifies the production of the fiber blank by weaving with the same number of warp yarn layers, while maintaining a greater number of warp yarn layers in the parts of the blank intended to form the blade of the turbine to be produced, and controlling the fiber content in the root of the blade to be produced.

[0017] According to another particular feature of the process of the invention, the fiber blank further comprises at least one buffer portion located between the first and second parts of the fiber blank, on the one hand, and the third and fourth parts of said fiber blank, on the other hand, said at least one buffer portion extending over several columns of weft yarns, warp yarns present in the first part of the fiber blank crossing warp yarns present in the second part of said fiber blank in said at least one buffer portion. These crossings between the warp yarns promote a homogeneous distribution of the yarns at the radii of connection of the first part with the second and third parts of the fiber blank during the shaping of the first part of the platform preform on the side of the first face of the blank.This avoids a lack of textile material at the connecting radii, which improves the mechanical properties of the blade in these areas.

[0018] According to another particular feature of the process of the invention, the weave pattern of at least a portion of the warp yarns in the first part of the fiber blank is modified in said at least one buffer portion so as to divert warp yarns from the first part of the fiber blank to a portion of the third part of the fiber blank located on the second face. This ensures continuity of the warp yarn network between the first part and the third and fourth parts of the blank. Furthermore, it is thus possible to divert a majority of the warp yarns from the second part to a portion of the third part that is not intended to be machined, thereby ensuring the continuity of the fiber network even if a portion of the third part of the fiber blank is machined.

[0019] The buffer portion also allows for the definition of a weaving pattern that controls the path of deflected warp threads in order to limit the forces applied to them during weaving. This minimizes the risk of thread breakage during weaving.

[0020] According to another particular feature of the method of the invention, the fibrous blank comprises a third portion corresponding to a fifth part of the fibrous blank extending along the longitudinal direction from the third intermediate position to the upper end of the fibrous blank, the method further comprising the deployment and shaping of a second segment of the fourth part and the fifth part of the fibrous blank to form respectively first and second parts of the heel preform.

[0021] According to another particular feature of the process of the invention, warp yarns from the fourth part of the fibrous blank cross warp yarns from the third part of said fibrous blank in the fifth part of the fibrous blank. These crossings between the warp yarns promote a Homogeneous distribution of fibers at the radii where the third and fourth parts of the fiber blank meet during the shaping of the first part of the heel preform on the second face of the blank. This prevents a lack of textile material at the radii, thus improving the mechanical properties of the blade in these areas.

[0022] According to another particular feature of the method of the invention, the fourth part comprises a segment partially separated by unbundling along the thickness direction of said fibrous blank into two sub-segments and in which the fifth part is partially separated along the thickness direction of said fibrous blank into two segments, the method further comprising the deployment and shaping of one of the two sub-segments of the segment of the fourth part and one of the two segments of the fifth part of the fibrous blank to form respectively first and second parts of preform of licks.

[0023] The invention also relates to a turbomachine blade obtained by the manufacturing process of the invention. Brief description of the drawings

[0024] [Fig-1] Fig. 1 is a very schematic partial cross-sectional view of part of a low-pressure turbine of a turbomachine

[0025] [Fig.2] Fig.2 is a very schematic perspective view of a moving wheel blade of the turbine of Fig.1.

[0026] [Fig.3] The [Fig.3] is a schematic plan view of a woven fibrous blank according to an embodiment of the invention intended for the production of a fibrous preform for a blade of the type of that of the [Fig.1],

[0027] [Fig.4] The [Fig.4] is a side view of the draft of the [Fig.3],

[0028] [Fig.5A] The [Fig.5A] is a schematic view at an enlarged scale of weaving plans of the rough [Fig.4] seen in section along the VA-VA plane of the [Fig.4],

[0029] [Fig.5B] The [Fig.5B] is a schematic view at an enlarged scale of weaving plans of the rough [Fig.4] seen in section along the VB-VB plane of the [Fig.4],

[0030] [Fig.6] The [Fig.6] is a schematic view at an enlarged scale of weaving plans of the rough [Fig.4] seen in section along plane VLVI of the [Fig.4],

[0031] [Fig.7] [Fig.7] illustrates a step in the production of a fibrous preform for a moving blade from the fibrous blank of [Fig.4],

[0032] [Fig.8] The [Fig.8] illustrates another step in the production of a fibrous preform for a moving blade from the fibrous blank of the [Fig.4],

[0033] [Fig.9] The [Fig.9] illustrates another step in the production of a fibrous preform for a moving blade from the fibrous blank of the [Fig.4]. Description of the implementation methods

[0034] The invention is applicable to various types of turbomachine blades, in particular moving wheel or stationary wheel blades of turbines or compressors of different gas turbine bodies. A stationary turbine or compressor wheel is understood here to be an assembly of non-rotating blades forming a turbine distributor or compressor rectifier.

[0035] An example of the implementation of a process of the invention applied to the manufacture of a low-pressure turbine wheel blade is described here.

[0036] The low pressure turbine shown very schematically and partially on [Fig.1] comprises a plurality of fixed wheels 100 alternating with movable wheels 200 in the direction of the X axis of the turbine, only one pair of fixed wheel and movable wheel being shown.

[0037] A fixed wheel 100 comprises a plurality of blades 110, each having a blade 120 extending between an inner platform 130 and an outer platform 140. Support elements 162, 164 project inward from the outer face of the inner platform 130, connecting to this outer face along connecting zones extending in a substantially circumferential direction. The support elements 162 and 164 have an L-shaped profile and support a block of abradable material 166. Mounting hooks 152 and 154 project outward from the outer face of the outer platform 140, connecting to this outer face along connecting zones extending in a substantially circumferential direction. The hooks 152 and 154 allow the blade to be mounted in a turbine housing 10.

[0038] A movable wheel 200 comprises a plurality of blades 210 (Figures 1 and 2) each having a blade 220 extending longitudinally between an inner platform 230 and an outer platform, or heel, 240. A foot 260 formed by a thicker portion, for example with a bulb-shaped cross-section, is connected by a strut 262 to the outer face of the inner platform 230. Heel scrapers 252, 254 project outwards from the outer surface of the heel 240, connecting to this outer face along connecting zones extending in a substantially circumferential direction.

[0039] The external faces of the platforms 130 and 230 and the internal faces of the platform 140 and the heel 240 define a gas flow vein in the turbine.

[0040] Each blade 210 is mounted on a turbine rotor 20 by engaging the foot 260 in a correspondingly shaped housing located on the periphery of the rotor. At its upstream and downstream end portions (in the direction F of gas flow), the platform 230 terminates in upstream and downstream winglets 232 and 234. The blade 220 has a curved profile in cross-section with a variable thickness between its leading edge 220a and its trailing edge 220b. The blade thickness can also vary in the longitudinal direction. The upstream 252 and downstream 254 winglets have profiles tooth-shaped, the ends of which can penetrate a layer of abradable material 14 carried by a turbine ring 18 to reduce the clearance between the blade tip and the turbine ring. At its upstream and downstream ends, the heel 240 can also terminate in upstream and downstream spurs 242 and 244.

[0041] A low-pressure turbomachine turbine arrangement such as succinctly described above is well known per se.

[0042] Figures 3 and 4 show very schematically a fibrous blank from which a fibrous blade preform can be shaped in order to obtain, after densification by a matrix and possible machining, a composite material blade with integrated blade, foot, inner platform, heel and heel scrapers of the type illustrated by [Fig.2].

[0043] The fibrous blank is produced by three-dimensional or multi-layer weaving, and only the outer layers of the different woven parts of the blank are shown for clarity (except in Figures 5A, 5B, and 6). The weaving is carried out, for example, with the warp direction corresponding to the longitudinal direction of the blade to be produced, each part of the blank comprising a plurality of layers of warp yarns linked together at least partially by weft yarns of a plurality of weft yarn layers.

[0044] 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.

[0045] Figure 3 shows in plan view a fibrous blank 301 from which a preform fibrous from the dawn 20 can be formed.

[0046] The blank 301 is obtained from a strip 300 woven by three-dimensional (3D) or multilayer weaving, the strip 300 generally extending in a longitudinal direction DL corresponding to the longitudinal direction of the blade to be manufactured. The weaving is carried out, for example, with warp threads extending in the longitudinal direction DL, it being noted that weaving with weft threads extending in this direction is also possible. A plurality of blanks 301 can be woven one after the other in the longitudinal direction DL. It is also possible to weave several parallel rows of blanks 301 simultaneously.

[0047] The fibrous blank 301 extends along the longitudinal direction DL between a lower end 301a and an upper end 301b intended to form The fiber blank 301 extends along a lateral direction Dt between a first edge 301c and a second edge 301d, which in the example described here form the leading and trailing edges of the blade to be produced, respectively. The fiber blank also extends along a thickness direction DE between a first face 301e and a second face 301f ([Fig. 4]), which in the example described here form the upper and lower surfaces of the blade to be produced, respectively.

[0048] The fibrous blank 301 comprises a first portion P1 intended to form part of the foot preform and part of the stile preform of the blade to be produced, a second portion P2 intended to form part of the blade preform of the blade to be produced, and a portion P3 intended to form part of the heel and swashplate preforms. Portion P2 is continuous with portion P2, while portion P3 is continuous with portion P2, sharing common warp yarn layers.

[0049] The lower part of the first portion PI, along a thickness direction DE, has a thickness EP1 greater than the thickness EP2 of the second portion P2 and the thickness EP3 of the third portion P3, in order to present a shape corresponding to that of the blade foot bulb to be produced. This greater thickness can be obtained by increasing the yarn count and / or the weft weave. Alternatively or in addition, an insert could be introduced locally during weaving. For a more detailed description of the production of a fibrous blank corresponding to a blade foot preform, reference may be made, for example, to US patent 2013 / 089429.

[0050] In the example of [Fig. 4], the first portion PI of the blank 301 comprises, along the thickness direction DE, a first part 302 located on the side of the first face 301e of the blank and a second part 303 separated from each other by a debonding 304. The debonding 304 extends across the entire width of the blank 301 along the transverse direction DT (weft dimension) and along the longitudinal direction DL (warp direction) over a length of the blank 301 extending from the lower end 301a of the blank 301 to the bottom 304a of the debonding 304, defining a first intermediate position p^ in the blank 301. The bottom of the debonding 304a extends between the first and second edges 301c and 301d of the rough 301 following the transverse direction DT. In the example described here, the first part 302 is intended to form a first part of the preform of the blade platform to be produced.

[0051] The second portion P2 of the blank 301 comprises, along the thickness direction De, a third part 305 and a fourth part 306 present on the side of the second face 301f of the blank, separated from each other by a debonding 307. The debonding 307 extends over the entire width of the blank 301 along the transverse direction DT (dimension in the weft direction) and along the longitudinal direction DL (warp direction) over a length of the blank 301 extending from a first bottom 307a of the debonding 307 defining a second intermediate position p; 2 in the blank 301 up to a second bottom 307b of the debond 307 defining a third intermediate position pi3 in the blank 301. The debond bottoms 307a and 307b extend between the first and second edges 301c and 301d of the blank 301 along the transverse direction DT.In the example described here, a first segment 306i of the fourth part 306 is intended to form a second part of the blade platform preform to be produced, while a second segment 3062 of the fourth part 306 is intended to form a first part of the blade heel preform to be produced. The third part 305 is intended to form a part of the blade or airfoil profile preform to be produced.

[0052] The third portion P3 of the blank includes, along the thickness direction DE, a fifth part 308 intended to form a second part of the preform of the blade heel to be produced.

[0053] Still in the example described here, the second segment 3062 of the fourth part 306 includes a debond 309 extending partially into the second segment 3062 to a debond bottom 309a and delimiting first and second sub-segments 3062i and 30622, the first sub-segment 3062[ being intended to form a part of the preform of blade slats to be produced while the fifth part 308 includes a partial debond 310 extending partially into the fifth part 308 to a debond bottom 310a delimiting first and second segments 3081 and 3082, the first segment 3081 being intended to form another part of the preform of blade slats to be produced.

[0054] In a well-known way, a debonding is provided 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.

[0055] In the example described here and according to an optional feature of the invention, the fibrous blank further includes a buffer zone TP in which warp yarns present in the first part 302 of the fibrous blank 301 cross warp yarns present in the second part 303 of the blank before being woven into the second portion P2 as explained below in detail.

[0056] According to the invention, the first portion 302 of the fibrous blank 301, which is intended to form the first portion of the blade platform preform to be produced, is formed in the first portion PI in said blank, while the fourth portion 306, which is intended to form the second portion of the blade platform preform to be produced, is formed in the second portion P2, which is located above the first portion PI along the longitudinal direction. Thus, the warp yarn layers of the fibrous blank used to form the platform preform portion are taken from two portions of said blank offset along the longitudinal direction DL of the latter. Consequently, unlike the prior art where the warp yarn layers used to form the two platform preform portions are taken symmetrically (i.e.on each side of the blank along the thickness direction) in the same portion located above a portion intended to form the foot preform part, the manufacturing process of the invention makes it possible, by means of a sampling of asymmetrical warp yarn layers in two portions of the blank offset along the longitudinal direction, to retain a greater number of warp yarn layers in the parts of the blank intended to form the blade of the blade to be produced.

[0057] Furthermore, and still in accordance with the invention, removing layers of warp yarns from the first portion PI of the fiber blank for the first part 302 makes it possible to reduce the number of warp yarn layers present in the second part 303 intended to form the preformed root portion of the blade to be produced. This makes it possible to obtain a fiber volume ratio in the root of the final blade much closer to that expected with regard to the targeted mechanical properties.

[0058] In the example described here, the total number of warp yarn layers in the fiber blank 301 is 24. In other words, in the example described here, the fiber blank is woven with the same number of warp yarn layers. The numbers in brackets in [Fig. 4] indicate an example of the distribution of warp yarn layers among the different parts of the fiber blank. Thus, in this example, the first part 302 comprises 6 layers, the second part 303 comprises 18 layers, the third part 305 comprises 14 layers, the fourth part 306 comprises 10 layers, and the fifth part 308 comprises 24 layers. Of course, the total number of warp yarn layers and their distribution may differ; the numbers given in the illustrated example are simply intended to facilitate understanding.

[0059] As can be seen and in accordance with the invention, the third part 305 used to form the preformed portion of the blade to be produced has a greater number of yarn layers, which allows for greater flexibility in defining the blade geometry. Furthermore, the second part 303 intended for Forming the preform foot portion of the blade here involves only 18 layers of warp yarns instead of 24 layers if the prior art process were used. An optimal fiber ratio in the fibrous foot reinforcement portion of the final blade can thus be achieved.

[0060] The fibrous blank of the invention is woven in one piece. By "in one piece", it is meant here that each part of the fibrous blank is linked by continuous warp yarns to one or more other adjacent parts along the longitudinal direction DL of the fibrous blank.

[0061] Figures 5A and 5B show, respectively, an even and an odd weave plane at the first and second portions PI and P2 of the fiber blank 301 according to the reference points VA and VB indicated in [Fig. 3]. [Fig. 5A] shows the path of warp yarns Ci to C24, each belonging respectively to one layer of warp yarns among the 24 layers of warp yarns used to weave the fiber blank 301 in an even weave plane. [Fig. 5B] shows the path of warp yarns Cr to C24', each belonging respectively to one layer of warp yarns among the 24 layers of warp yarns used to weave the fiber blank 301 in an odd weave plane. The even and odd planes are alternately repeated along the transverse direction DT (weft direction).

[0062] The warp yarns Ci to C24 and Cr to C24- are woven in a three-dimensional or multilayer weave with weft yarns Tb T2 and T3 belonging to layers of weft yarns. In the example described here, the weft yarns Tb T2 and T3 each have a different count (size). The weft yarns Ti present throughout the entire fiber blank 301 have the lowest count, while the weft yarns T2 and T3, present only in the second part intended to form the preformed foot portion of the blade to be produced, have a count higher than the weft yarns Ti in order to locally create a thicker layer and present a shape corresponding to that of the bulb of the blade foot to be produced.

[0063] In the example described here, the warp yarns Ci to C6 and Cr to C6' present in the first section 302 cross in the buffer section TP the warp yarns C7 to Ci6 and C7- to Ci6' present in the second section 303 before joining the third and fourth sections 305 and 306. This weave structure used in the even planes at the buffer section TP promotes a homogeneous distribution of yarns at the radii of connection of the first section 302 with the second section 303 and the third section 304 during the shaping of the first section of the platform preform on the side of the first face 301e of the blank (here the extrados face of the blade to be produced). The buffer section TP extends over several columns of weft yarns. The buffer section also allows for the definition of a weave pattern enabling control The warp threads are diverted to limit the stresses applied to them during weaving. This minimizes the risk of thread breakage during weaving.

[0064] The weave used in the odd planes at the buffer portion promotes a homogeneous distribution of the wires at the radii of connection of the fourth part 306 with the second part 303 and the third part 304 when shaping the second part of the platform preform on the side of the second face 301f of the blank (here the intrados face of the blade to be made).

[0065] Furthermore, on [Fig.5A] (even plane), the warp threads Ci to C5 of the first part 302 are referred to the part of the third part 305 located on the side of the second face 301f (here the intrados face of the blade to be produced) which corresponds to a part of the blade which is not machined, the warp thread C6 being referred to the fourth part 306. This ensures continuity of warp threads between the first part 302 and the third and fourth parts 305 and 306 of the blank. On [Fig.5B] (odd plane), a majority of the warp threads, here the warp threads C7 to C24 of the second part 303 are referred to the part of the third part 305 located on the side of the second face 301f (here the intrados face of the blade to be made) which corresponds to a part of the blade which is not machined and to the fourth part 306.This ensures continuity of warp threads between the second part 303 and the third and fourth parts 305 and 306 of the blank.

[0066] However, we do not depart from the scope of the invention when the fibrous blank does not include a buffer portion and the warp yarns all follow the same weave pattern throughout the length of the blank, that is to say without crossing and turning of the warp yarns into offset parts of the blank.

[0067] Figure 6 shows a weaving plane at the level of the second and third portions P2 and P3 of the fiber blank 301 according to the reference point VI indicated in Figure 3, the weave structure shown in Figure 6 being identical in the even and odd planes. Figure 6 shows the path of warp yarns Ci to C24, each belonging respectively to one layer of warp yarns among the 24 layers of warp yarns used to weave the fiber blank 301. The warp yarns Ci to C24 are woven in a three-dimensional or multilayer weave with weft yarns Tb

[0068] In the example described here, warp threads present in the third part 305 cross the warp threads present in the fourth part 306 before joining the fifth part 308. These warp thread crossings promote a homogeneous distribution of threads at the radii of connection of the fourth part 306 with the fifth part 305 during the shaping of the second segment 3062 of the fourth part 306 intended to form a first part of the heel preform. the blade to be made on the side of the second face 301f of the blank (here the intrados face of the blade to be made).

[0069] However, we do not depart from the scope of the invention when the fibrous blank does not include crossing of warp yarns between buffer portion and when the warp yarns all follow the same weave structure throughout the length of the blank, that is to say without crossing and redirection of warp yarns in offset parts of the blank.

[0070] Figures 7 to 9 show very schematically how a fibrous preform having a shape close to that of the blade to be manufactured can be obtained from the fibrous blank 301 described above.

[0071] The fourth part 306 of the fibrous blank 301 is cut at a cutting line C in order to separate the two segments 306i and 3062 ([Fig.4]).

[0072] The first part 302 is deployed along arrow fi of [Fig.4]. The segment 306i is deployed along arrow f2 of [Fig.4]. The first part 302 and the deployed segment 306i form a plate 413 ([Fig.7]) intended, after molding, to form part of the preform of the inner platform of the blade to be manufactured.

[0073] Segment 3062 is unfolded along arrow f3 of [Fig. 4]. The fifth part 308 is folded and unfolded along arrow f4 of [Fig. 4]. The unfolded segment 3062 and fifth part 307 form a plate 414 ([Fig. 7]) intended to form a preform for the heel and a preform for the heel blades of the blade to be manufactured.

[0074] As can be seen in [Fig. 7], deploying the fifth section 308, which is thicker than segment 3062, on the side of the first face 301e (here, the extrados face of the blade to be produced), allows the excess thickness of this fifth section 308 to be positioned on the lower face 414a of the plate 414. In this case, the machining of the excess thickness is carried out on the side of the lower face 414a of the plate 414, which limits the size of the weft crossings while ensuring the continuity of the yarns. If the thickest section, here the fourth section 308, were deployed on the side of the second face 301f of the blank (here, the intrados face of the blade to be produced), the excess thickness to be machined would be located on the upper face of the plate, which implies a significant weft crossing in the heel that could lead to yarn breaks during weaving.

[0075] Next, as shown in [Fig. 8], segment 3081 of the fifth part 308 and sub-segment 3062i of the second segment 3062 can be deployed to form preform parts of the blade heel scrapers to be manufactured. The excess thickness present on the lower face 414a of the plate 414 has been machined.

[0076] A fibrous preform 410 of the blade to be manufactured is then obtained by molding with deformation of the part 305 to reproduce the curved profile of the blade and deformation of the plates 413, 414 to reproduce shapes similar to those of the inner platform and the heel of the blade, as well as to give the inner platform preform and the heel preform orientations corresponding to the desired orientations of the inner platform and the heel relative to the longitudinal direction in the blade to be manufactured, as shown in [Fig. 9] (the mold not being shown). This yields the preform 410 with a portion of the blade preform 420, a portion of the foot preform 460 (with a stilt preform), a portion of the inner platform preform 430, a portion of the heel preform 440, and portions of the heel scraper preforms 452, 454.

[0077] The manufacturing of the blade continues with the consolidation and densification of the fibrous preform 410.

[0078] In a manner known per se, consolidation can be achieved by impregnation with a resin that is cross-linked and pyrolyzed, the quantity of consolidation resin being chosen so that the pyrolysis residue binds the preform fibers sufficiently to allow the preform to be handled while retaining its shape without the assistance of tooling. A ceramic precursor resin can be used, for example. Impregnation with the consolidation resin can be carried out by infusion or injection into the mold or by impregnation at the fiber blank stage, prior to shaping. Alternatively, also in a manner known per se, consolidation can be achieved by partial densification with a ceramic material using a known process of chemical vapor infiltration (CVI).

[0079] The consolidated preform can be extracted from the forming tooling to carry out densification by a ceramic matrix, for example silicon carbide SiC. Densification can be carried out by CVI.

[0080] The densification can be carried out in two successive steps separated by a step of machining the blade to the desired shapes and dimensions.

[0081] It should be noted that pre-machining can be carried out after consolidation and before densification, in particular pre-machining of the blade, the inner platform and the heel to eliminate excess thickness and pre-machining of the heel scrapers, in order to get closer to the shape of the blade of the [Fig.2].

[0082] It should also be noted that a debrittlement interphase coating can be formed between the preform fibers and the ceramic matrix, as is well known in itself.

[0083] Once the preform is densified by the matrix, a blade is obtained whose geometry corresponds to the final blade 210 of [Fig.2].

[0084] Other well-known densification methods can also be used to densify the fibrous preform with a matrix.

Claims

1. Demands A method for manufacturing a turbomachine blade (210) 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 (301), the fibrous blank extending along a longitudinal direction (DL) between a lower end (301a) and an upper end (301b), along a lateral direction (DT) between a first edge (301c) and a second edge (301d) and along a thickness direction (DE) perpendicular to the longitudinal (DL) and transverse (Dt) directions between a first face (301e) and a second face (301i), the fibrous blank (301) comprising a first portion (PI) extending along the longitudinal direction (DL) from the lower end (301a) of the fibrous blank and up to a first intermediate position (p^) distant from the lower end of the fibrous blank,the fibrous blank being separated by unbinding (304) in said first portion (PI) and along the thickness direction (DE) of said fibrous blank into a first part (302) present on the first face (301e) of the fibrous blank (301) and a second part (303), the first part (302) comprising a number of warp yarn layers less than the number of warp yarn layers of the second part (303), the fibrous blank (301) comprising a second portion (P2) extending along the longitudinal direction (DL) from a second intermediate position (pi2) located above or at the same level as the first intermediate position (p^) and up to a third intermediate position (pi3) distant from the second intermediate position and set back from the upper end (301b) of the fibrous blank,the fibrous blank (301) being separated by debonding (307) in said second portion (P2) and along the thickness direction (DE) of said fibrous blank into a third part (305) and a fourth part (306) present on a second face (30If) of the fibrous blank (301), the third part (305) comprising a number of warp yarn layers greater than the number of warp yarn layers of the fourth part (306), - the formation, from the fibrous blank (301), of a fibrous preform (410) of the blade to be produced, by unfolding and shaping the first part (302) and at least a first segment (3060) of the fourth part (306) to form respectively first and second parts of platform preform, the second part (303) forming a part of foot preform and the third part (305) forming at least one part of blade preform, - the densification of the preform by a matrix to obtain a blade (210) in composite material having at least a foot (260), an integrated platform (203) and a blade (220).

2. A method according to claim 1, wherein the number of warp yarn layers present in the first and second parts (302, 303) of the fibrous blank (301) is equal to the number of warp yarn layers present in the third (305) and fourth parts (306) of said fibrous blank.

3. A method according to claim 1 or 2, wherein the fiber blank (301) further comprises at least one buffer portion (PT) present between the first and second parts (302, 303) of the fiber blank, on the one hand, and the third and fourth parts (305, 306) of said fiber blank, on the other hand, said at least one buffer portion (PT) extending over several columns of weft yarns, warp yarns (Ci-C6, Ci'-C6) present in the first part (302) of the fiber blank crossing warp yarns present in the second part (303) of said fiber blank in said at least one buffer portion (PT).

4. A method according to claim 3, wherein the weaving pattern of at least a portion of the warp yarns (C1-C5, Cr-C5) in the first part (302) of the fiber blank is modified in said at least a buffer portion (PT) so as to deflect warp yarns from the first part of the fiber blank towards a portion of the third part (305) of the fiber blank (301) present on the side of the second face (30If).

5. A method according to any one of claims 1 to 4, wherein the fibrous blank (301) comprises a third portion (P3) corresponding to a fifth part (308) of the fibrous blank extending along the longitudinal direction (DL) from the third intermediate position (pi3) to the upper end (301b) of the fibrous blank, the process further comprising the deployment and shaping of a second segment (3062) of the fourth part and the fifth part of the fibrous blank to form respectively first and second parts of heel preform.

6. A method according to claim 5, wherein warp yarns from the fourth part (306) of the fibrous blank (301) cross warp yarns from the third part (305) of said fibrous blank in the fifth part (308) of the fibrous blank.

7. A method according to claim 5 or 6, wherein the fourth part (306) of the fibrous blank (301) comprises a segment (3062) partially separated by unbinding (309) along the thickness direction (DE) of said fibrous blank into two sub-segments (3062i, 30622) and wherein the fifth part (308) is partially separated along the thickness direction of said fibrous blank into two segments (308i, 3082), the method further comprising the deployment and shaping of one (3062[ ) of the two sub-segments of segment (3062) of the fourth part (306) and of one (3080) of the two segments of the fifth part (308) of the fibrous blank (301) to form respectively first and second parts of preform of licks (452, 454).

8. Turbomachine blade made of composite material obtained by the manufacturing process according to any one of claims 1 to 7.

Images