METHOD FOR MANUFACTURING A BLADE FOR AN AIRCRAFT TURBINE ENGINE

Description

Domaine technique de l'invention

[0001] The invention relates to the technical field of methods for manufacturing blades for aircraft turbomachines. The invention relates more particularly to methods for manufacturing blades made of composite material, which are, for example, rotating or fixed. Arrière-plan technique

[0002] The state of the art is illustrated by document FR-A1-3059268.

[0003] As is well known, an aircraft turbomachine comprises a fan allowing the suction of an air flow divided into a primary flow and a secondary flow. The primary flow passes through the turbomachine engine while the secondary flow is directed towards a secondary vein.

[0004] The primary flow is compressed within, for example, a low-pressure compressor and then a high-pressure compressor of the engine. The compressed air is then mixed with fuel and burned within an annular combustion chamber arranged downstream of the series of compressors. The gases formed by the combustion pass through a high-pressure turbine and a low-pressure turbine located downstream of the combustion chamber and which drive the compressor rotors. The gases finally escape through a nozzle whose cross-section allows the acceleration of these gases to generate propulsion.

[0005] Turbomachine components such as the fan, compressors, or turbines include blades that act on the airflow. For example, compressor blades compress the primary airflow.

[0006] A blade typically comprises a blade that has an aerodynamic shape and thus comprises a pressure face and an extrados face connected to the pressure face by a leading edge and a trailing edge. To reduce the weight of the blade, the blade is formed from a composite material comprising reinforcing fibers embedded in a polymer matrix. In order to protect the blade from degradation caused by the impact of foreign bodies, it is known to coat the leading edge with a metal foil. Attaching the metal foil to the leading edge presents challenges.

[0007] Indeed, a blade manufacturing process consists of providing a fiber preform and then impregnating the preform during a resin injection step and then polymerizing the resin. Then, during a subsequent step, the metal foil is fixed to the leading edge of the blade by gluing. The polymerization of the glue is carried out in an oven. The manufacturing time of the blade using such a manufacturing process is long because it is necessary for the impregnation step to be completed to fix the metal foil to the leading edge.

[0008] In order to reduce manufacturing time, document FR-A1-3008920 teaches fixing the metal foil on the leading edge during the impregnation step. This document teaches that the mold can be equipped with a system for positioning and holding the foil. However, this system is not entirely satisfactory. Indeed, the foil is fixed in position in the mold but the relative position of the foil with respect to the blade cannot be determined precisely. Indeed, it is difficult to position the blade with respect to the foil once in the mold. Also, the metal foil can be displaced during mold closing and / or injection in the absence of a suitable positioning and holding system. Thus, at the end of the manufacturing process, a radial and / or axial offset of the metal foil with respect to the leading edge can be observed. These poor positions lead to non-conformities of the blade.

[0009] There is therefore a need to provide a manufacturing method that can reduce positioning defects of the metal foil on the leading edge. Résumé de l'invention

[0010] To this end, the invention proposes a method of manufacturing a blade comprising a vane for an aircraft turbomachine comprising the following steps: (100) providing a fiber preform of the blade, the fiber preform comprising a leading edge, a trailing edge, a pressure face connected to an extrados face by the leading edge and the trailing edge, (200) providing a metal foil of elongated shape and comprising at least one indexing recess, (300) providing an injection mold comprising at least upper and lower parts intended to cooperate together to delimit an internal volume and each defining an imprint of the blade, and at least one of these upper and lower parts comprising at least one projecting positioning element, (400) arranging the fiber preform in the injection mold, (500) coating the leading edge of the fiber preform with the metal foil, and inserting the projecting positioning element into the indexing recess so as to hold the metal foil in position on the leading edge,(600) inject a resin into the injection mold in order to impregnate the fiber preform and fix the metal foil on the leading edge.

[0011] Thus, according to the invention, the metal foil is placed on the leading edge of the preform which is arranged in the injection mold in order to simultaneously impregnate the fiber preform and fix the metal foil on the leading edge. This makes it possible to reduce the manufacturing times of the blade.

[0012] Furthermore, according to the invention, the metal foil has at least one indexing recess and the mold comprises at least one positioning projection on the upper and / or lower part. When inserting the fiber preform into the mold, the positioning projection is inserted into the indexing recess, which makes it possible to fix the metal foil in position on the leading edge during the material injection operation. This makes it possible to reduce the risks of the metal foil moving relative to the leading edge during the resin injection. Consequently, according to the invention, the risks of providing non-compliant blades are reduced.

[0013] The invention may comprise one or more of the following features, taken in isolation from each other or in combination with each other: the positioning protrusion is a stud provided on an inner surface of the upper portion or the lower portion; the stud has a cylindrical or conical shape; the stud has a threaded outer surface; the metal foil comprises a first side fin and a second side fin connected to the first side fin by a central portion, the indexing recess being provided on the first or second side fin; in step (200), the metal foil comprises a central portion and an excess portion arranged on either side of the central portion, the indexing recess being located on one or each of the excess portions; the indexing recess is an orifice or a notch;the metal foil comprises two indexing recesses respectively comprising a first orifice and a second orifice opposite the first orifice and in that the upper or lower part comprises a first projecting positioning element intended to cooperate with the first orifice and a second projecting positioning element intended to cooperate with the second orifice; the fiber preform comprises an additional indexing recess; the method comprises the following step after step (600): (700) machining the blade so as to remove the indexing recess.;

[0014] The disclosure also relates to an injection mold for implementing the manufacturing method according to any one of the preceding characteristics, comprising: at least lower and upper parts each having an imprint of the blade and intended to cooperate together to define an internal volume for receiving the fiber preform and the metal foil, at least one of these upper and lower parts comprising at least one projecting positioning element intended to cooperate with the indexing recess of the metal foil so as to hold the metal foil in position on the leading edge. Brève description des figures

[0015] Other characteristics and advantages will emerge from the following description of a non-limiting embodiment of the invention with reference to the appended drawings in which: [ Fig.1 ] there figure 1 is a schematic representation in longitudinal section of a half aircraft turbomachine; [ Fig.2 ] there figure 2 is a schematic perspective representation of a blade according to a first embodiment, [ Fig.3 ] there figure 3 is a schematic perspective representation of a blade according to a second embodiment, [ Fig.4 ] there figure 4 is a cross-sectional view of the dawn of the figure 2 Or 3 , [ Fig.5 ] there figure 5 is a schematic view of a fiber preform and a metal foil, [ Fig.6 ] there figure 6 is a schematic view of a fiber preform and a metal foil according to an alternative embodiment of the figure 5 , [ Fig.7a ] there figure 7a is a cross-sectional view of a mold in an open position in which the fiber preform and the metal foil are arranged, [ Fig.7b ] there figure 7b is a cross-sectional view of the mold in a closed position and in which the fiber preform and the metal foil are arranged, [ Fig.7c ] there figure 7c is a cross-sectional view of the mold in a closed position and in which the fiber preform and the metal foil are arranged, according to an alternative embodiment of the figure 7b , [ Fig.7d ] there figure 7d is a cross-sectional view of the mold in an open position and in which the fiber preform and the metal foil are arranged, according to an alternative embodiment of the figure 7a , [ Fig.8 ] there figure 8 is a schematic perspective representation of the injection mold according to the invention, [ Fig.9 ] there figure 9 is a block diagram of the manufacturing process according to the invention. Description détaillée de l'invention

[0016] An aircraft turbomachine 1 is for example represented on the figure 1 . The turbomachine 1 extends along a longitudinal axis A. It comprises from upstream to downstream in the direction of flow of the gases F along the longitudinal axis A, a fan 2, at least one compressor such as a low-pressure compressor 3 and a high-pressure compressor 4, a combustion chamber 5, at least one turbine 6 such as a high-pressure turbine and a low-pressure turbine, and a nozzle (not shown). The rotor of the low-pressure turbine is connected to the fan 2 and to the rotor of the low-pressure compressor 3 by a low-pressure shaft (not shown). The rotor of the high-pressure turbine is connected to the rotor of the high-pressure compressor 4 by a high-pressure shaft (not shown).

[0017] The turbomachine 1 further comprises a rectifier 10. The rectifier makes it possible to straighten the flow at the outlet of a rotor located upstream in order to provide maximum thrust at the outlet of the turbomachine 1. In the particular example of the figure 1 , the rectifier 10 is located downstream of the blower 2 and makes it possible to straighten the secondary flow F2. The rectifier 10 is for example arranged between the low pressure compressor 3 and the high pressure compressor 4.

[0018] The blower 2 allows the suction of an air flow dividing into a primary flow F1 and a secondary flow F2. The primary flow F1 passes through the engine of the turbomachine 1 while the secondary flow F2 is directed towards a secondary vein surrounding the primary vein.

[0019] The primary flow F1 is compressed within the low-pressure compressor 3 and then the high-pressure compressor 4. The compressed air is then mixed with fuel and burned within the combustion chamber 5. The gases formed by the combustion pass through the high-pressure turbine and the low-pressure turbine. The gases finally escape through the nozzle, the cross-section of which allows the acceleration of these gases to generate propulsion. The secondary flow F2 passes through the rectifier 10, which accelerates the circulation speed of the secondary flow F2 to generate propulsion.

[0020] The fan 2, the compressor, the turbine and the rectifier 10 are equipped with a set of blades 11. The blades 11 are movable or fixed in rotation about the longitudinal axis A. The blades 11 extend radially relative to the longitudinal axis A. With reference to the figures 2 And 3, each blade 11 comprises a blade 12 and a metal foil 14 fixed on the blade 12. The blade 12 extends along an elongation axis X. The elongation axis X of the blade 12 extends radially relative to the longitudinal axis A of the turbomachine 1 after mounting the blade 11 on the turbomachine 1. The blade 12 has an aerodynamic profile. The blade 12 thus comprises an extrados face 12e and an intrados face 12i connected by a leading edge 12a and a trailing edge 12b. The blade 12 thus extends along a transverse axis Y between the leading edge 12a and the trailing edge 12b. The transverse axis Y is perpendicular to the elongation axis X. The blade 12 also extends longitudinally along the elongation axis X between a first end and a second end opposite the first end.

[0021] The blade 12 is made of a composite material. The composite material comprises a polymer matrix and a fiber reinforcement embedded in the matrix. The composite material is, for example, an organic matrix composite (OMC). The matrix is, for example, a thermoplastic or thermosetting polymer matrix. The thermosetting material is, for example, an epoxy polymer. The fiber reinforcement comprises fibers that are, for example, carbon fibers or glass fibers. The fibers are organized in the form of a fiber preform.

[0022] The metal foil 14 extends over the leading edge 12a and advantageously along the entire length of the leading edge 12a. The metallic material of the metal foil 14 is, for example, titanium or an alloy such as steel, for example, stainless steel or a nickel and cobalt alloy (NiCo). The metal foil 14 has an elongated dihedral shape. It is intended to protect the leading edge 12a from external impacts. As best seen in the figure 4 , the metal foil 14 has a V-shaped or U-shaped cross-section. The metal foil 14 comprises a first lateral fin 14a and a second lateral fin 14b connected to the first lateral fin 14a by a central portion 14j. The first and second lateral fins 14a, 14b define between them a cavity in which the leading edge 12a is arranged. The first lateral fin 14a has a first free longitudinal end and the second lateral fin 14b has a second free longitudinal end which are opposite the central portion 14j. The longitudinal ends extend respectively on the intrados face 12i and the extrados face 12e of the blade 12. Each lateral fin 14a, 14b has a first edge and a second edge opposite the first edge along the elongation axis X. The edges extend transversely relative to the longitudinal ends.Advantageously, the thickness of the metal foil 14 is variable. For example, the thickness of the central portion 14j is greater than the thicknesses of the first and second lateral fins 14a, 14b. Advantageously, the thickness of the first and second lateral fins 14a, 14b decreases in the direction of the trailing edge 12b of the blade 12. The first and second lateral fins 14a, 14b are tapered in the direction of the trailing edge 12b of the blade 12.

[0023] The metal foil 14 is fixed to the leading edge 12a by gluing. The blade 11 comprises at least one layer of glue 16 arranged between the blade 12 and the metal foil 14. An additional layer of adhesive (not shown) may also be arranged between the protective shield 14 and the blade 12 in order to improve the fixing of the protective shield 14.

[0024] According to a first embodiment shown in the figure 2 , the blades 11 are rotatable. They equip for example the fan 2, the low pressure compressor 3 and / or the high pressure compressor 4 and / or the high pressure turbine and / or the low pressure turbine. According to this first embodiment, the blade 11 further comprises a root 13. The root 13 is in particular connected to the second end of the blade 11. It is intended to be fixed to a disk (not shown) for example rotatable around the longitudinal axis A of the turbomachine 1.

[0025] According to a second embodiment shown in the figure 3 , the vanes 11 equip the rectifier 10. Such vanes 11 equipping the rectifier 10 are known by the English term “Outlet Guide Vane” (OGV). According to this second embodiment, the vane 11 further comprises a first platform 120a and a second opposite platform 120b. The first platform 120a is integral with the first end of the vane 11 and the second platform 120b is integral with the second end of the vane 11.

[0026] Blade 11 is manufactured using a resin transfer molding process, known by the acronym RTM for "Resin Transfer Molding" in English.

[0027] A method of manufacturing the blade 11 according to the invention will now be described with reference to the figure 9

[0028] In a first step 100, a fiber preform 20 is provided, illustrated for example in the figure 5 . The fiber preform 20 constitutes the fiber reinforcement of the composite material of the blade 12. The fiber preform 20 comprises a three-dimensional weave of the reinforcing fibers. The fibers are, as described above, carbon fibers or glass fibers. The fiber preform 20 has the same profile as the blade 12. The fiber preform 20 thus extends along the elongation axis X and has an aerodynamic profile. It has a leading edge 20a, a trailing edge 20b, a pressure face 20i connected to an extrados face by the leading edge 20a and the trailing edge 20b.

[0029] According to an advantageous embodiment of the invention, the fiber preform 20 comprises, along the X axis, a central portion 21c and a first excess portion 21a and a second excess portion 21b arranged on either side of the central portion 21c. The excess portions 21a and 21b are, for example, intended to be at least partially removed during a subsequent machining step. The excess portions 21a and 21b are located outside the dynamic portion of the fiber preform 20, i.e. outside the portion of the blade 12 intended to come into contact with the primary or secondary flow F1, F2.

[0030] Advantageously, and as illustrated on the figure 6 , the fiber preform 20 comprises at least one additional indexing recess 22. The additional indexing recess 22 is for example produced by water jet cutting. The additional indexing recess 22 is for example formed on the first part and / or the second excess part 21a, 21b. The additional indexing recess 22 is for example a notch. According to an example not shown, the additional indexing recess 22 is an orifice. The orifice has an axis which extends perpendicular to the elongation axis X of the fiber preform 20. The orifice is preferably a through orifice. The additional indexing recess 22 is produced on the leading edge 20a of the fiber preform 20. The fiber preform 20 comprises for example an additional indexing recess 22 produced on the first excess part 21a and an additional indexing recess 22 produced on the second excess part 21b.

[0031] Furthermore, the method comprises a step 200 of providing the metal foil 14. Step 200 can be carried out before, after or simultaneously with step 100.

[0032] In step 200, the metal foil 14 comprises, in particular along the elongation axis X, a central portion 14c and a first excess portion 14d and a second excess portion 14e arranged on either side of the central portion 14c. The excess portions 14d, 14e are intended to cover the excess portions 21b, 21a of the leading edge 20a of the fiber preform 20.

[0033] According to the invention, in step 200, the metal foil 14 comprises at least one indexing recess 23 shown for example in the figure 7a . The indexing recess 23 opens onto the surface opposite the fiber preform 20. The indexing recess 23 is for example a notch or an orifice. The axis of the orifice is perpendicular to the longitudinal axis X of the fiber preform 20. The indexing recess 23 is located on at least one excess portion 14d, 14e or on each excess portion 14d, 14e. Thus, the metal foil 14 may comprise a first indexing recess 23 such as an orifice and a second indexing recess 23 such as an orifice opposite the first indexing recess 23. The indexing recess 23 may be located on the first lateral fin 14a and / or the secondary lateral fin 14b as shown in the figure 7c . The indexing recess 23 is for example provided throughout the thickness of the first lateral fin 14a and / or the second lateral fin 14b. The adhesive layer 16 is furthermore arranged in the metal foil 14 so that the adhesive layer 16 is arranged between the metal foil 14 and the fiber preform 20 after the metal foil 14 has been arranged on the leading edge 20a. This adhesive layer 16 may also be formed during a subsequent injection step 600.

[0034] The method further comprises a step 300 of providing an injection mold 17. Step 300 can be carried out before, after or simultaneously with the above steps. The injection mold 17 is shown for example in the figure 8 .

[0035] The injection mold 17 comprises at least an upper part 17a and a lower part 17b. The upper part 17a is for example movable and the lower part 17b is for example fixed. The injection mold 17 can thus be opened or closed by rotation or by translation for example of the upper part 17a.

[0036] The upper part 17a and the lower part 17b each comprise an internal face having an imprint 17c of the blade 11 to be produced. By “internal face” is meant the face which is inside the injection mold 17 when the latter is closed and which faces the internal face of the other part. When the mold 17 is closed, the imprint 17c of each of the upper and lower parts 17a, 17b define an internal volume 17d having the shape of the blade 11 to be produced and in which the fiber preform 20 and the metal foil 14 are placed.

[0037] The injection mold 17 comprises an injection port 18 for a resin. The injection port 18 is for example located on the upper part 17a.

[0038] As best seen on the figures 7a à 7d , according to the invention, the injection mold 17 further comprises at least one projecting positioning element 19. The projecting positioning element 19 makes it possible to position and maintain in position the metal foil 14 on the leading edge 20a in the injection mold 17 during the injection of the resin. The projecting positioning element 19 has a shape complementary to the indexing recess 23. The projecting positioning element 19 is for example a stud having a cylindrical shape as shown in the figure 7d or conical as shown in the figures 7a à 7c . Advantageously, the stud has a threaded external surface. This makes it easier for the stud to cooperate with the metal foil 14. Advantageously, the projecting positioning element 19 is removable. By “removable” it is understood that the projecting positioning element 19 can be added or removed from the injection mold 17 without damaging the injection mold 17. Indeed, the projecting positioning element 19 wears during the injection cycles and a replacement of the projecting positioning element 19 is necessary. The removable nature of the projecting positioning element 19 therefore facilitates maintenance of the injection mold 17. According to an alternative, the projecting positioning element 19 is permanently mounted in the injection mold 17. It is for example machined or welded to the injection mold 17.

[0039] According to an example of embodiment shown on the figures 7a et 7b , the projecting positioning element 19 is located on the upper part 17a of the injection mold 17. According to another exemplary embodiment shown in the figure 7c , the positioning protruding element 19 is located on the lower part 17b of the injection mold 17.

[0040] Advantageously, the injection mold 17 comprises a first projecting positioning element 19a and a second projecting positioning element 19b. The projecting positioning elements 19a, 19b are for example located at the ends of the lower 17b and / or upper 17a parts.

[0041] The positioning protrusion 19b is located on the inner surface of the lower and / or upper portions 17b, 17a. The inner surface is the surface facing the fiber preform 20 after insertion into the injection mold 17.

[0042] Then in a step subsequent to the above steps, the method comprises a step 400 of arranging the fiber preform 20 in the injection mold 17 with a view to impregnating the fiber preform 20.

[0043] The method according to the invention further comprises a subsequent step 500 during which the leading edge 20a of the fiber preform 20 is coated with the metal foil 14. The indexing recess 23 and the additional indexing recess 22 are aligned during this step, which makes it possible to precisely position the metal foil 14.

[0044] During this step, the positioning protrusion 19 is inserted into the indexing recess 23 and into the additional indexing recess 22. This can take place when closing the injection mold 17 as shown in the figure 7b , when the positioning protruding element 19 is arranged on the upper part 17a which is the movable part of the injection mold 17 or upon insertion of the fiber preform 20 as shown in the figure 7c , when the positioning protruding element 19 is arranged on the lower part 17b which is the fixed part of the injection mold 17. Thus, the cooperation of the positioning protruding element 19 and the indexing recess 23 makes it possible to precisely position the fiber preform 20 and the metal foil 14 in the injection mold 17.

[0045] Then, a step 600 of injecting the resin into the mold is carried out via the injection port 18. This step allows the impregnation of the fiber preform 20 and the fixing of the metal foil 14 on the leading edge 12a. During the injection step, the metal foil 14 is held in position on the leading edge 12 thanks to the cooperation of the projecting positioning element 19 and the indexing recess 23. The resin is the material forming the matrix of the blade 12. The temperature of the injection mold 17 during the injection step is between 50°C and 200°C, advantageously between 50°C and 180°C.

[0046] Optionally, depending on the resin material, a curing sub-step 610 may be carried out for the polymerization of the adhesive layer 16 and the resin. The curing step is carried out at a temperature between 120°C and 250°C.

[0047] Advantageously, after step 600, the method comprises a step 700 of machining the blade 11 so as to remove the indexing recess 23 and the additional indexing recess 22 when it is present. According to this step, the blade 11 is machined so as to at least partially remove the excess parts 21a, 21b, 14d, 14e. The indexing recesses 23, 22 are thus produced on the offcuts of the blade 11 and do not impact the properties of the blade 11.

[0048] Furthermore, the indexing recess 22 of the fiber preform 20 facilitates the pairing of the positioning protruding element 19. This also makes it possible to reduce local deformations of the weaving of the fiber preform 20 during the insertion of the positioning protruding element 19 into the indexing recess 23 of the metal foil 14. Also, the precision of the positioning of the fiber preform 20 relative to the leading edge 12a is improved.

Claims

1. A method for manufacturing a vane (11) comprising a blade (12) for an aircraft turbine engine (1) comprising the following steps: (100) providing a fibrous preform (20) of the blade (12), the fibrous preform (20) comprising a leading edge (20a), a trailing edge (20b), a pressure side face (20i) connected to a suction side face by the leading edge (20a) and the trailing edge (20b), (200) providing an elongate metal foil (14) comprising at least one indexing recess (23), (300) providing an injection mould (17) comprising at least upper and lower parts (17a, 17b) intended to cooperate together to delimit an internal volume (17d) and each defining a pattern (17c) of the vane (11), and at least one of these upper and lower parts (17a, 17b) comprising at least one projecting positioning element (19), (400) arranging the fibrous preform (20) in the injection mould (17), (500) coating the leading edge (20a) of the fibrous preform (20) with the metal foil (14), and inserting the projecting positioning element (19) into the indexing recess (23) so as to hold the metal foil (14) in position on the leading edge (20a), (600) injecting a resin into the injection mould (17) in order to impregnate the fibrous preform (20) and to attach the metal foil (14) to the leading edge (20a).

2. The manufacturing method according to the preceding claim, characterised in that the projecting positioning element (19) is a nipple provided on an inner surface of the upper part (17a) or of the lower part (17b).

3. The manufacturing method according to the preceding claim, characterised in that the nipple has a cylindrical or conical shape.

4. The manufacturing method according to claim 2 and / or 3, characterised in that the nipple has a threaded external surface.

5. The manufacturing method according to any one of the preceding claims, characterised in that the metal foil (14) comprises a first lateral fin (14a) and a second lateral fin (14b) connected to the first lateral fin (14a) by a central portion (14j), the indexing recess (23) being provided on the first or the second lateral fin (14a, 14b).

6. The manufacturing method according to any one of the preceding claims, characterised in that in step (200) the metal foil (14) comprises a central part (14c) and an excess part (14d, 14e) arranged on either side of the central part (14c), the indexing recess (23) being located on one or each of the excess parts (14d, 14e).

7. The manufacturing method according to any of the preceding claims, characterised in that the indexing recess (23) is an orifice or a notch.

8. The manufacturing method according to any one of the preceding claims, characterised in that the metal foil (14) comprises two indexing recesses (23) respectively comprising a first orifice and a second orifice opposite the first orifice and in that the upper or lower part (17a, 17b) comprises a first projecting positioning element (19a) intended to cooperate with the first orifice and a second projecting positioning element (19b) intended to cooperate with the second orifice.

9. The manufacturing method according to any one of the preceding claims, characterised in that the fibrous preform (20) comprises an additional indexing recess (22).

10. The manufacturing method according to any one of the preceding claims, characterised in that it further comprises the following step after step (600): (700) machining the vane (11) so as to remove the indexing recess (23).