Method for manufacturing a blade for an aircraft turbine engine

Abstract

The invention relates to a method for manufacturing a blade (30) for an aircraft turbine engine, the method comprising: a) producing a three-dimensional preform by weaving fibres; b) solidifying the preform with a polymerisable resin to form a body (36) of the airfoil; and c) forming serrations (35), wherein this step is carried out by placing the body (36) of the airfoil in a mould (38) comprising a cavity (40) corresponding to the serrations (35) to be formed, and by thermocompressing a material (42) in the mould (38), wherein this material (42) is intended to be secured to the body (36) of the airfoil and to adopt the shape of the cavity (40), the assembly formed by the body (36) of the airfoil and the material (42) secured thereto forming the airfoil (32) of the blade (30).

Description

[0001] DESCRIPTION

[0002] TITLE: METHOD FOR MANUFACTURING A BLADE FOR AN AIRCRAFT TURBOMACHINE

[0003] Technical field of the invention

[0004] The present invention relates to a method for manufacturing a blade for an aircraft turbomachine, as well as a blade obtained by this method.

[0005] Technical Downstream Plan

[0006] The state of the art includes in particular the documents FR-A1-3 073 017, USAI-2022 / 402218, FR-A1-3 108 143, CN-B-113 635 587 and US-A1-2017 / 226865.

[0007] An aircraft turbomachine typically comprises a gas generator that drives at least one propeller. The gas generator includes at least one compressor, one combustion chamber, and at least one turbine. The rotor, or one of the rotors, of the gas generator is connected to the propeller rotor for rotational drive.

[0008] A propeller can be shrouded. This is the case for a fan in a turbomachine such as a turbojet or turbofan, for example.

[0009] A propeller can be unfaired. This is the case, for example, with a turboprop engine.

[0010] A propeller consists of a hub and an annular row of blades mounted around the hub. The blades can be fixed, thus having a fixed angular position around their axes of aspect. Alternatively, the blades can have variable pitch, meaning they can be rotated around axes called pitch axes, which generally extend along the blades' axes of aspect. The pitch axes can be radial axes relative to the propeller's axis of rotation. A blade typically comprises a blade with an upper and lower surface, as well as a leading and trailing edge. It may also include a platform attached to one end of the blade, defining the blade's pitch axis. The platform is generally mounted in a hole in the hub and centered and guided in rotation within that hole around the pitch axis.

[0011] It is known to manufacture such blades from metallic, ceramic, or composite materials. A well-known composite material consists of a body made of woven carbon fibers embedded in a polymer matrix, such as an epoxy matrix. The leading edge of the blade can be reinforced with a bonded metal shield.

[0012] The evolution of turbomachine performance tends towards an increase in their bypass ratio, which is mainly achieved by increasing the diameter of the propellers and therefore the length and mass of their blades.

[0013] Furthermore, a so-called slow-speed, high-bypass-ratio propeller comprises a reduced number of blades with an increased chord to improve the propulsive efficiency of the turbomachine.

[0014] In the case of a shrouded propeller, the nacelle surrounding the propeller includes internal acoustic treatment that reduces noise emissions outside the turbomachine.

[0015] In the case of an unfaired propeller, other solutions must be found to reduce propulsion noise. This is particularly the case for the turbomachine illustrated in Figure 1. This turbomachine 10 comprises an upstream propeller 12, which includes rotor blades 14 with variable pitch, and a downstream stator 16, which includes stator blades 18 also with variable pitch.

[0016] To remedy the noise emission problem, a noise reduction technology already known on fans and inspired in particular by the wings of nocturnal birds of prey consists of providing serrations 20 on the trailing edges of the rotor blades 14 or on the leading edges of the stator blades 18 (figures 2 and 3).

[0017] Serrations 20 of a leading or trailing edge are formed by an alternation of teeth 20a and hollows 20b along this edge. The serrations can cause variations in the blade chord as a function of the radial height, with varying thicknesses and a very thin leading or trailing edge.

[0018] The 20a teeth are designed to reduce noise in the mid-emission spectrum without significantly worsening other frequencies at other engine speeds.

[0019] The angular setting of the blades implies variable acoustics of the blades depending on the engine speed and the orientation of the blades.

[0020] It has been observed that, in most engine operating conditions, serrations help reduce noise. However, a significant increase in noise has also been observed when the blades are set in reverse or thrust reversal mode. In the case of a rotor blade, the trailing edge serrations are oriented upstream in reverse mode, which greatly disrupts the aerodynamic flow. The serrations then become counterproductive.

[0021] The thrust reversal phase is a phase which, on the contrary, should be the least noisy possible because it generally takes place in a nearby urban environment.

[0022] Another disadvantage of the previous technique is related to the fact that the serrations cannot be made with the same material as the woven blades because the serrations are too thin, and they would be too fragile and in particular brittle.

[0023] The present invention offers a solution to at least some of the problems of the prior art, which is simple, effective and economical.

[0024] Summary of the invention The invention relates to a method for manufacturing a blade for an aircraft turbomachine, this blade comprising a blade having an intrados and an extrados, as well as a leading edge and a trailing edge, the leading or trailing edge having serrations (35) formed by an alternation of teeth and hollows along this edge, the method comprising: a) the production of a three-dimensional preform by weaving fibers, and b) the solidification of the preform with a polymerizable resin, characterized in that steps a) and b) make it possible to produce a blade body without the serrations, and the method further comprises: c) the formation of the serrations, this formation being carried out by mounting the blade body in a mold having an impression of the serrations to be formed, and by thermo-compressing a material in the mold, this material being intended to bond with the blade body and to adopt the shape of the impression,the assembly formed by the body of the blade and the bonded material forming the blade of the blade.

[0025] The invention thus proposes to create the serrations after the preform has solidified with the resin. The serrations are created by thermocompression, that is, by a treatment combining an increase in temperature and pressure. A material is used specifically for creating the serrations and is thermocompressed with the solidified preform, called the blade body, so that it conforms to the shape of the mold and thus adopts a serrated form. Thermocompression also allows the material to be bonded to the preform. The process according to the invention may comprise one or more of the following features or steps, taken individually or in combination:

[0026] - the process includes, between steps b) and c), a step i) of preparation or treatment of the surface of the blade body intended to be bonded to the material; -- said preparation or surface treatment is chosen from sandblasting, plasma treatment and a film of adhesive;

[0027] - the material extends over the body of the blade, only along the edge of the blade containing the serrations;

[0028] - the material is bonded to the body of the blade by chemical adhesion and / or mechanical anchoring;

[0029] - mechanical anchoring is achieved by filling the housings in the blade body with the material during step c);

[0030] - the process includes, between steps b) and c), a step i) of forming the housings for example by machining the blade body;

[0031] - the dwellings each have a general dovetail shape;

[0032] - the process further includes, after step c), a step d) of coating the blade with a consolidation layer which covers both the body of the blade and the material;

[0033] - the consolidation layer is made of polyurethane;

[0034] - during step c), the mold is heated to a temperature above 100°C, and for example between 120 and 150°C;

[0035] - during step c), thermocompression is carried out at a pressure greater than 50 bars, and for example between 70 and 140 bars;

[0036] - the material comprises at least one thermosetting polymer;

[0037] - the material contains charges;

[0038] - the fillers include fibers, particularly carbon fibers.

[0039] The invention also relates to a blade for an aircraft turbomachine, this blade being obtained by a process as described above.

[0040] Advantageously, the blade comprises a blade having an intrados and an extrados, as well as a leading edge and a trailing edge, the leading or trailing edge having serrations formed by an alternation of teeth and hollows along this edge, the blade comprising a blade body and a material attached to the blade body and defining said serrations, the blade body comprising a three-dimensional preform made by weaving fibers and embedded in a resin.

[0041] The blade according to the invention may comprise one or more of the following features, taken individually or in combination with each other:

[0042] -- the resin and the material are both epoxy-based;

[0043] -- the material comprises at least one thermosetting polymer;

[0044] -- the material includes fillers; such as fibers, in particular carbon fibers;

[0045] -- the loads are of the DLF (Discontinuous Long Fibre) type;

[0046] -- the material is SMC (Sheet Molding Compound) or BMC (Bulk Molding Compound);

[0047] -- the material is that marketed by the company Hexcel under the name HexMC®-i.

[0048] Brief description of the figures

[0049] Other features and advantages will become apparent from the following description of a non-limiting embodiment of the invention with reference to the accompanying drawings in which:

[0050] [Fig.1] Figure 1 is a schematic perspective view of an unfaired propeller turbomachine and an unfaired stator, the propeller and stator having variable pitch blades;

[0051] [Fig.2] Figure 2 is a schematic view of a variable pitch rotor or propeller blade;

[0052] [Fig.3] Figure 3 is a schematic view of a variable-pitch stator or rectifier blade;

[0053] [Fig.4] Figure 4 is a schematic view of a blade according to the invention;

[0054] [Fig.5] Figure 5 is a perspective view of a thermocompression mold and shows a step in a process according to the invention;

[0055] [Fig.6] Figure 6 is another schematic view of the mold and also illustrates the step of the process according to the invention; [Fig.7a-7b] Figures 7a and 7b are very schematic partial cross-sectional views of the thermocompression mold and also illustrate the aforementioned step;

[0056] [Fig. 8] Figure 8 is a schematic cross-sectional view of a blade according to the invention; and

[0057] [Fig.9] Figure 9 is a view similar to that of Figure 6 and illustrates an alternative embodiment.

[0058] Detailed description of the invention

[0059] Figures 1 to 3 have been described above.

[0060] The invention relates to an aircraft turbomachine blade, which may be the turbomachine of Figure 1 or another turbomachine.

[0061] Figure 4 illustrates an embodiment of a blade 30 according to the invention for an aircraft turbomachine. The invention is applicable to any type of blade, stator, or rotor. The blade 30 can therefore be a rotor blade or a stator blade. Furthermore, the blade can be of the variable-pitch type or not.

[0062] The blade 30 comprises a blade 32 having an intrados 32a and an extrados 32b, as well as a leading edge 32c and a trailing edge 32d.

[0063] One of the edges 32c, 32d of the blade 30 has serrations 35 formed by an alternation of teeth 35a and hollows 35b along this edge. This could be the leading edge 32c or the trailing edge 32d, and the invention applies to both cases, although Figure 4 and the following figures focus on the presence and formation of serrations on the trailing edge 32d.

[0064] The invention relates to a method for manufacturing the blade 30.

[0065] The process includes the following steps: a) the creation of a three-dimensional preform by weaving fibers, and b) the solidification of the preform with a polymerizable resin.

[0066] These steps are known, particularly within the framework of a process such as RTM (Resin Transfer Molding). In the context of the present invention, these steps are used to produce a blade body without the serrations 35.

[0067] The invention thus proposes to create the serrations 35 after the solidification of the blade body. It is therefore understood that the formation of the serrations does not in itself impact the RTM-type process.

[0068] The process according to the invention comprises, after steps a) and b), a step c) of forming the serrations 35.

[0069] As illustrated in 5, 6 and 7a-7b, this formation is achieved by mounting the body 36 of the blade in a mold 38 having an impression 40 of the serrations 35 to be formed, and by thermo-compressing a material 42 in the mold 38.

[0070] This material 42 is intended to bond with the body 36 of the blade and to adopt the shape of the imprint 40.

[0071] The assembly formed by the body 36 of the blade and the attached material 42 forms the blade 32 of the blade 30.

[0072] Figure 5 shows a two-part mold 38 between which the blade body 36 is positioned. The two parts of the mold 38 define a cavity for housing the blade body. This cavity includes the aforementioned impression 40.

[0073] In Figure 6 and Figure 7a, we see that the material 42 is deposited on a part of the body 36 of the blade or is injected into the cavity of the mold 38, then in Figure 7b, the mold 38 is closed and subjected to a thermocompression treatment so that the material 42 fills the cavity 40 and takes its shape.

[0074] In figures 4 and 8, it can be seen that the material 42 extends over the body 36 of the blade, only along the edge of the blade containing the serrations 35. It is not necessary to mold material 42 over the entire body 36 of the blade.

[0075] The material 42 can be bonded to the blade body 36 by chemical adhesion and / or mechanical anchoring. In the case of Figure 8, simple chemical adhesion is used to bond the material 42 to the blade body 36.

[0076] In the case of figure 9, it is also a mechanical anchor that ensures this connection.

[0077] Mechanical anchoring can be achieved by filling the housings 44 of the blade body 36 with the material 42 during step c). The process then preferably includes, between steps b) and c), a step i) of forming the housings 44 for example by machining the blade body 36.

[0078] The housings 44 can each have a general dovetail shape as schematically illustrated in figure 9. They can extend over the entire transverse extent of the body 36 and thus open respectively on the intrados and extrados of this body 36.

[0079] The process may include, after step c), a step d) of coating the blade 32 with a consolidation layer 46 which covers both the body 36 of the blade and the material 42 (see figure 8). The consolidation layer is, for example, made of polyurethane.

[0080] With regard to thermocompression in step c), the mold 38 is preferably heated to a temperature above 100°C, and for example between 120 and 150°C.

[0081] Thermocompression is preferably carried out at a pressure greater than 50 bars, and for example between 70 and 140 bars.

[0082] Thermocompression can be carried out for a duration of between 15s and 40min depending on the nature of the material and the molding temperature.

[0083] The material 42 used for forming the serrations 36 preferably comprises at least one thermosetting polymer. This material 42 may include fillers, such as fibers, in particular carbon fibers.

[0084] Discontinuous Long Fiber (DLF) fillers and Sheet Molding Compound (SMC) or Bulk Molding Compound (BMC) materials can be used. These fillers and materials have the advantage of being able to flow, allowing them to fill complex shapes such as the impression 40 with serrations 35.

[0085] The material 42 used can be that marketed by the company Hexcel under the name HexMC®-i.

[0086] The present invention also relates to a blade 30 for an aircraft turbomachine, this blade 30 being obtained by the process described above.

[0087] The blade 30 comprises a blade 32 having an intrados 32a and an extrados 32b, as well as a leading edge 32c and a trailing edge 32d. The leading edge 32c or trailing edge 32d has serrations 35 formed by an alternation of teeth 35a and hollows 35b along this edge.

[0088] The blade 32 comprises a blade body 36 and the aforementioned material 42 attached to the blade body 36 and defining the serrations 35. The blade body 36 comprises a three-dimensional preform made by weaving fibers and embedded in a resin which may be different from the material forming the serrations 35.

[0089] Both resin and material 42 can be epoxy-based but may have different formulations and in particular different fillers or additives.

[0090] The process according to the invention may include, between steps b) and c), a step i) of preparing or treating the surface of the blade body 36 intended to be bonded to the material 42. This surface preparation or treatment is preferably selected from sandblasting, plasma treatment, and the application of an adhesive film. This activates the bonding zone to ensure better affinity between the resins.

[0091] The invention offers several advantages, including:

[0092] • the ability to create complex shapes

[0093] • possibility of integrating the shape into existing blades,

[0094] • Ability to repair the geometry throughout the part's lifecycle,

[0095] • no influence on the integrity of the blade structure.

Claims

DEMANDS 1. A method for manufacturing a blade (30) for an aircraft turbomachine, this blade (30) comprising a blade (32) having an intrados (32a) and an extrados (32b), as well as a leading edge (32c) and a trailing edge (32d), the leading edge (32c) or trailing edge (32d) having serrations (35) formed by alternating teeth (35a) and hollows (35b) along this edge, the method comprising: a) the production of a three-dimensional preform by weaving fibers, and b) the solidification of the preform with a polymerizable resin, characterized in that steps a) and b) allow the production of a blade body (36) without the serrations (35), and the method further comprises: c) the formation of the serrations (35), this formation being carried out by mounting the blade body (36) in a mold (38) comprising an imprint (40) of the serrations (35) to be formed, and by thermo-compressing a material (42) in the mold (38),this material (42) being intended to bond with the body (36) of the blade and to adopt the shape of the imprint (40), the assembly formed by the body (36) of the blade and the bonded material (42) forming the blade (32) of the blade (30).

2. Method according to claim 1, wherein it comprises, between steps b) and c), a step i) of preparation or treatment of the surface of the body (36) of the blade intended to be joined to the material (42).

3. Method according to claim 1 or 2, wherein the material (42) extends over the body (36) of the blade, only along the edge of the blade (32) having the serrations (35).

4. A method according to any one of the preceding claims, wherein the material (42) is bonded to the body (36) of the blade by chemical adhesion and / or mechanical anchoring.

5. Method according to claim 4, wherein the mechanical anchoring is achieved by filling housings (44) in the blade body (36) with the material (42) during step c).

6. Method according to claim 5, wherein it comprises, between steps b) and c), a step i) of forming the housings (44) for example by machining the body (36) of blade.

7. Method according to claim 5 or 6, wherein the housings (44) each have a general dovetail shape.

8. A method according to any one of the preceding claims, wherein it further comprises, after step c), a step d) of coating the blade with a consolidation layer (46) which covers both the body (36) of the blade and the material (42).

9. Method according to the preceding claim, wherein the consolidation layer (46) is made of polyurethane.

10. A method according to any one of the preceding claims, wherein, during step c), the mold (38) is heated to a temperature above 100°C, and for example between 120 and 150°C.

11. A method according to any one of the preceding claims, wherein, during step c), thermocompression is carried out at a pressure greater than 50 bars, and for example between 70 and 140 bars.

12. A method according to any one of the preceding claims, wherein the material (42) comprises at least one thermosetting polymer.

13. A method according to any one of the preceding claims, wherein the material (42) comprises fillers.

14. A method according to the preceding claim, wherein the fillers comprise fibers, in particular carbon fibers.

15. Blade (30) for an aircraft turbomachine, this blade (30) being obtained by a process according to any one of the preceding claims and comprising a blade (32) having an intrados (32a) and an extrados (32b), as well as a leading edge (32c) and a trailing edge (32d), the leading edge (32c) or trailing edge (32d) having serrations (35) formed by a alternating teeth (35a) and hollows (35b) along this edge, the blade (32) comprising a blade body (36) and a material (42) attached to the blade body and defining said serrations (35), the blade body (36) comprising a three-dimensional preform made by weaving fibers and embedded in a resin.

16. Blade (30) according to the preceding claim, wherein the resin and the material are both epoxy-based.

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