Methods for reworking or repairing blades, including the leading edge.

Abstract

A method for manufacturing a blade includes: - a forming step in which a blade structure (10) is formed, and - a positioning step in which a leading edge (20) is positioned on a leading edge (136) of the blade structure (10). The leading edge (200) is attached to the leading edge (136) by means of a heat-sensitive adhesive material.

Description

Technical Field

[0001] This disclosure relates to the general field of blade manufacturing, and particularly to the manufacturing of blades for aircraft engines that are made of composite materials and include, in particular, a leading edge made of metal. Background Technology

[0002] The metallic leading edge on aircraft engine blades made of composite materials provides the composite blade assembly with protection against abrasion / erosion and / or impact from foreign objects. This is especially true for fan blades of aircraft turbine engines, which are exposed to the risk of ingesting birds, hail, ice, etc.

[0003] The manufacture of the fan blades first includes forming composite blades comprising fiber reinforcements via a matrix densified from a thermosetting resin or thermoplastic material.

[0004] Once the composite blade is obtained, a protective metal leading edge needs to be assembled onto its leading edge. For this purpose, a metal shield, prepared by machining processes such as stamping, forming, or electroforming, is bonded to the leading edge of the composite blade. This process can be performed in a mold to ensure proper adhesion of the metal shield.

[0005] Examples of composite blades with a metallic leading edge are specifically described in documents US 2007 / 092379 and US2016 / 0167269.

[0006] Bonding the metal leading edge to the leading edge of a composite blade is a delicate operation, especially in terms of the precise positioning of the metal leading edge on the composite blade.

[0007] Therefore, it may be necessary to correct the positioning of the metal leading edge after bonding.

[0008] In addition, the metal leading edge may be damaged, especially after events such as impacts with foreign objects, or it may wear down after a certain period of operation on the composite blade. In these cases, the metal leading edge must be replaced.

[0009] However, once bonded, the metal leading edge cannot be removed from the composite blade without damaging it due to the adhesive forces between the metal leading edge and the composite blade. This hinders the rework and / or replacement of the metal leading edge of the composite blade. Summary of the Invention

[0010] Therefore, the main objective of this invention is to provide a method for manufacturing blades, particularly composite blades, equipped with a leading edge, particularly of metal, which does not have the aforementioned disadvantages.

[0011] According to the invention, the objective is achieved by a method for manufacturing a blade, particularly a composite material blade, including an additional leading edge, particularly of metal, and the method comprises at least:

[0012] - A forming step, in which a blade structure including at least one leading edge is formed; and

[0013] - Positioning step, in which the leading edge is positioned on the leading edge portion of the blade structure.

[0014] More specifically, in the positioning step, the leading edge is attached to the leading edge using a heat-sensitive adhesive material, particularly a heat-sensitive adhesive.

[0015] The use of thermally adhesive materials provides the possibility of removing the leading edge after adhesion without damaging the constituent materials of the blade structure.

[0016] By heating the blade to a temperature above the melting point of the heat-sensitive adhesive material, the adhesive material loses its adhesive properties. The leading edge can then be carefully removed without applying any stress to the blade structure, especially composite blade structures.

[0017] According to a specific feature of the manufacturing method of the present invention, the heat-sensitive adhesive material can have a melting temperature lower than the damage temperature of the material of the blade structure.

[0018] Another specific feature of the manufacturing method according to the invention is that the heat-sensitive adhesive material can have a melting point between 90°C and 120°C.

[0019] In another specific feature of the manufacturing method according to the present invention, the heat-sensitive adhesive material is a neoprene rubber adhesive.

[0020] Another object of the present invention is a method for reworking or repairing blades, particularly composite blades having an additional leading edge, said method comprising at least:

[0021] - Heating step, in which the blade is heated to a temperature higher than the melting temperature of the heat-sensitive adhesive material;

[0022] - A removal step, in which the leading edge is separated from the blade; and

[0023] - Repositioning step, in which the leading edge or a new leading edge is attached to the leading edge of the blade structure.

[0024] The leading edge can be positioned and corrected after attachment during the positioning step without damaging the constituent materials of the blade structure. This prevents the scrapping of the initially manufactured blade or blade structure.

[0025] Similarly, when the leading edge is damaged or worn during the use of the blade, it can be replaced without damaging the constituent materials of the blade structure, thereby extending the service life of the blade.

[0026] Another subject of the invention is a composite blade for an aircraft engine, comprising an additional metal leading edge and a composite blade structure, said blade comprising, in the longitudinal direction:

[0027] - Leaf roots,

[0028] - Petiole, and

[0029] - airfoil body, said airfoil body:

[0030] - Extending longitudinally between the petiole and the leaf tip, and

[0031] - Extends horizontally between the front and back edges, and

[0032] - Leading edge, which is attached to the leading edge of the composite blade structure.

[0033] More specifically, the blade further includes a layer of heat-sensitive adhesive material, particularly a heat-sensitive adhesive, located between the leading edge and the leading edge.

[0034] According to a specific feature of the blade of the present invention, the heat-sensitive adhesive material can have a melting temperature lower than the damage temperature of the composite material of the blade.

[0035] According to another specific feature of the blades of the present invention, the heat-sensitive adhesive material can have a melting temperature between 90°C and 120°C.

[0036] According to another specific feature of the blades of the present invention, the heat-sensitive adhesive material is a neoprene rubber adhesive. Attached Figure Description

[0037] The invention will be better understood by reading the following detailed description of embodiments for illustrative purposes, with reference to the accompanying drawings, which illustrate non-limiting embodiments that will contribute to a complete understanding of the invention and its implementation, and, where appropriate, help to define it, wherein:

[0038] [ Figure 1 ] Figure 1 This is a schematic perspective view of a blade with an additional leading edge according to an embodiment of the present invention;

[0039] [ Figure 2 ] Figure 2 It is along Figure 1 A cross-sectional view of the middle blade in plane II-II; and

[0040] [ Figure 3 ] Figure 3 This is an exploded schematic perspective view showing the leading edge of the present invention assembled onto the blade structure. Detailed Implementation

[0041] The present invention is applicable to the forming of blades for aircraft engines, particularly those made of composite materials, having a leading edge that is particularly metallic, such as fan blades.

[0042] Figure 1 This is a schematic perspective view of a blade 30 equipped with an additional leading edge 20 according to an embodiment of the present invention.

[0043] More specifically, Figure 1 A blade 30 is shown, which includes a blade structure 10, particularly a composite material blade structure, in the longitudinal direction D L The above includes:

[0044] - Leaf root 11, and

[0045] - Airfoil 13, which in the lateral direction D T Extending upwards, located between the following:

[0046] - Frontier 20, and

[0047] - Trailing edge 132.

[0048] The blade structure 10 may also include the petiole 12.

[0049] The airfoil 13 also includes a lower surface 133 and an upper surface 134, which are respectively located along the orthogonal direction D of the airfoil 13. o The two sides extend between the leading edge 20 and the trailing edge 132, in the orthogonal direction D. o With longitudinal direction D L and horizontal direction D T Form an orthogonal coordinate system.

[0050] Airfoil 13 may also include blade tip 135.

[0051] The leading edge 20 (which is specifically formed by a metal shield) is attached to all or part of the leading edge 136 of the airfoil 13.

[0052] The trailing edge 132 is formed by the trailing edge 14 of the airfoil 13.

[0053] In one particular embodiment, the blade 30 is a composite material blade, except for the leading edge 20.

[0054] Figure 2 It is along Figure 1Cross-sectional view of plane II-II of the middle blade 30.

[0055] like Figure 2 As shown, the leading edge 20 is positioned on the leading edge 136 of the airfoil 13 and is attached, particularly by adhesion, especially by adhesive bonding, using a layer of adhesive material 40 or a thin film of adhesive material 40.

[0056] According to the present invention, the adhesive material may be a heat-sensitive adhesive material.

[0057] In this article, "thermal adhesive material" refers to an adhesive material that loses its adhesive properties and / or rigidity when it reaches or exceeds a certain temperature (also known as melting temperature).

[0058] In one particular embodiment, the adhesive material is an adhesive, especially a heat-sensitive adhesive.

[0059] The method for manufacturing the blade 30 includes at least one forming step in which a blade structure 10 is formed, the blade structure 10 being, in particular, a composite material blade structure.

[0060] For composite blade structures, blade structure 10 is obtained in the manufacturing process from fiber reinforcements that have been densified by a matrix.

[0061] In this document, "composite blade structure" refers to the blade body, which includes most of the constituent parts of the final blade 30, particularly the blade root 11 and the airfoil 13, but excludes the leading edge 20 formed by a shield, particularly of metal, which is attached to the composite blade structure 10, the blade body being entirely of composite material.

[0062] The composite blade structure 10 is manufactured from a fiber preform, which can be obtained in various ways known to those skilled in the art. Typically, the preform can be obtained directly by three-dimensional weaving, for example, yarns formed from carbon fibers, or by laying two-dimensional fiber fabrics.

[0063] The manufacture of a composite fan blade 30, obtained by three-dimensional weaving of a fiber reinforcement followed by matrix densification, is specifically described in document US 2005 / 084377. In the embodiments described herein, the fan blade preform 30 is obtained by three-dimensional weaving of carbon fiber yarns.

[0064] In a known manner, a blade structure preform 10 is impregnated with a liquid composition containing a matrix material precursor. This precursor is typically in the form of a polymer, such as a resin, and may optionally be diluted in a solvent.

[0065] The preform is placed in a sealable mold and includes a cavity having the shape of a molded blade structure 10, which in particular may have a helical shape corresponding to the final shape of the airfoil having the desired aerodynamic profile.

[0066] The mold is then closed, and a liquid matrix precursor (e.g., epoxy resin) is injected into the entire mold to impregnate all fibrous portions of the preform.

[0067] Impregnation of the blade fiber preform can be carried out, in particular, through resin transfer molding (RTM) process.

[0068] The conversion of the precursor to the matrix (e.g., through polymerization) is achieved through heat treatment, typically by heating the mold and crosslinking the polymer after removing any solvent. The preform is retained in the mold with a structural shape that matches the desired aerodynamic profile.

[0069] The matrix can be obtained from epoxy resins (such as high-performance epoxy resins sold by CYTEC under reference number PR 520), or from liquid carbon or ceramic matrix precursors.

[0070] For the forming of carbon or ceramic matrices, heat treatment requires the pyrolysis of organic precursors to convert the organic matrix into a carbon or ceramic matrix, depending on the precursors used and the pyrolysis conditions.

[0071] As an example, liquid carbon precursors can be resins with relatively high residual carbon content, such as phenolic resins, while liquid ceramic precursors (especially silicon carbide (SiC) precursors) can be polycarbosilane (PCS) type resins, polytitanium carbosilane (PTCS) type resins, or polysilazane (PSZ) type resins.

[0072] Multiple consecutive cycles, from impregnation to heat treatment, can be performed to achieve the desired degree of densification.

[0073] The resulting part is then demolded. The part is trimmed to remove excess resin, and chamfering may be performed.

[0074] Because it is molded, the part has the required dimensions, so no further machining is required.

[0075] Thus, a blade structure 10 is obtained, and in particular, the blade structure 10 is a composite material blade structure.

[0076] Figure 3 This is an exploded schematic perspective view showing the leading edge 20 assembled onto the blade structure 10 of the present invention.

[0077] like Figure 3As shown, the blade structure 10 includes a blade root 11 and an airfoil 13. The blade structure 10 may also include a petiole 12.

[0078] Airfoil 13 extends between blade root 11 and blade tip 150 of airfoil 13, and more specifically between peduncle 12 and blade tip 150 of airfoil 13.

[0079] The airfoil 13 includes the leading edge 136 of the airfoil 13 with blade 30. The leading edge 136 is used to receive, in particular, a metal shroud to form the leading edge 20 of the final blade.

[0080] like Figure 3 As shown, the leading edge 20 includes:

[0081] - Inner wall 201, which is used for attachment to the leading edge 136 of the blade structure 10, and

[0082] - Outer wall 202, which defines the outline of the leading edge 20 of the final blade 30.

[0083] The leading edge 20 also includes a nose 203 from which two wing edges 204 and 205 extend.

[0084] The manufacture of the blade 30 includes a positioning step of positioning the leading edge 20 on the blade structure 10, particularly by adhesion, especially by adhesive bonding.

[0085] More specifically, such as Figure 3 As shown, the leading edge 20 is attached to the leading edge 136 of the airfoil 13 of the blade structure 10, and an adhesive material film 40 or an adhesive material layer 40 is inserted between the inner wall 201 of the leading edge 20 and the leading edge 136 of the blade structure 10.

[0086] The adhesive material layer 40 between the leading edge 20 and the leading edge 136 of the blade structure 10 can be obtained in different ways. It can correspond to sandwiching the adhesive material between the inner wall 201 of the leading edge 20 and the leading edge 136 of the blade structure 10, and the assembled whole is placed in a heated mold to activate (in particular, polymerize) the adhesive properties of the adhesive material layer 40.

[0087] The adhesive material layer 40 may also be deposited directly on the inner wall 201 of the leading edge and / or deposited on the leading edge 136 of the blade structure 10. The assembly is carried out in a mold that can apply pressure to the leading edge 20 and the blade structure 10 to be assembled, and optionally, an adhesive heat treatment, particularly adhesive bonding, is performed.

[0088] The steps for positioning the leading edge 20 on the blade structure 10 are specifically described in document FR 2 992 887 A1.

[0089] According to the present invention, the leading edge 20 is attached to the blade structure 10, which is in particular a composite material blade structure, using a heat-sensitive adhesive material (especially a heat-sensitive adhesive).

[0090] As mentioned earlier, heat-sensitive adhesive materials can lose their adhesive properties and / or rigidity when they reach and exceed a certain temperature (also known as the melting temperature).

[0091] The melting temperature of the heat-sensitive adhesive material is preferably lower than the damage temperature of the blade structure 10, and especially lower than the damage temperature of the composite material of the blade structure 10.

[0092] The damage temperature corresponds to the temperature at which the composite material begins to exhibit thermal degradation. At this damage temperature, the composite material may show signs of softening and / or decreased mechanical properties. Furthermore, at this damage temperature, the composite material may exhibit weakening of the fiber-matrix interface, reducing the composite material's strength. The damage temperature depends on the composite material under consideration.

[0093] In addition, the melting temperature is preferably higher than the temperature encountered when the blade 30 is running, in order to avoid any durability problems with the leading edge 20 when the blade 30 is in use.

[0094] Therefore, the melting temperature of the heat-sensitive adhesive material is preferably between 90°C and 120°C.

[0095] In particular, the heat-sensitive adhesive material can be a neoprene adhesive.

[0096] After the leading edge 20 was located, it was obtained Figure 1 The blade shown is 30.

[0097] The use of the thermally adhesive material of the present invention has advantages in the rework of blades 30 (especially composite blades 30 with a metal leading edge 20) and / or in the replacement of the leading edge 20 during blade 30 maintenance.

[0098] During the manufacturing of blade 30 (as described above), blade 30 may be improperly positioned during the positioning step, or the leading edge 20 may be damaged after positioning.

[0099] In this case, according to the present invention, the blade 30 is heated to a temperature higher than the melting temperature of the heat-sensitive adhesive material. Once the melting temperature is reached, the leading edge 20 to be repositioned can be gradually separated without damaging the blade structure 10, especially the composite material that does not damage the blade structure 10.

[0100] The leading edge 20 is then repositioned or replaced to avoid scrapping the originally manufactured blade 30 and / or blade structure 10.

[0101] Similarly, once put into use, the leading edge 20 of the blade 30 may be damaged due to events such as impact with foreign objects, or due to wear after the blade 30 has been in operation for a certain period of time.

[0102] In this case, the blade 30 is heated to a temperature higher than the melting temperature of the heat-sensitive adhesive material. Once the melting temperature is reached, the damaged and / or worn leading edge 20 can be gradually separated without damaging the blade structure 10, especially the composite material that does not damage the blade structure 10.

[0103] Then the leading edge 20 can be replaced, thereby extending the service life of the blade 30.

Claims

1. A method for reworking or repairing a blade (30), the blade being particularly a composite blade, comprising a leading edge (20) attached to the leading edge (136) of a blade structure (10) by means of a heat-sensitive adhesive material, the method comprising at least: In the heating step, the blade (30) is heated to a temperature higher than the melting temperature of the heat-sensitive adhesive material; The removal step, in which the leading edge (20) is separated from the blade (30); as well as The repositioning step involves attaching the leading edge (20) or a new leading edge (20) to the leading edge (136) of the blade structure (10).

2. The method according to claim 1, wherein, The heat-sensitive adhesive material has a melting temperature lower than the damage temperature of the composite material of the blade (30).

3. The method according to claim 1, wherein, Thermosensitive adhesive materials have melting points between 90°C and 120°C.

4. The method according to any one of claims 1 to 3, wherein, The heat-sensitive adhesive material is a neoprene rubber adhesive.

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