Method for reworking or repairing a blade comprising a leading edge

Abstract

The invention relates to a method for manufacturing a blade, the method comprising: - a shaping step, during which a blade structure (10) is formed; and - a positioning step, during which a leading edge (20) is positioned on the front edge (136) of the blade structure (10). The leading edge (200) is attached to the front edge (136) by means of a heat-sensitive adhesive material.

Description

[0001] Description

[0002] Title of the invention:

[0003] METHOD FOR REBUILDING OR REPAIRING A BLADE COMPRISING A LEADING EDGE

[0004] Technical Field

[0005] The present invention relates to the general field of the manufacture of blades, in particular made of composite material, comprising a leading edge, in particular metallic, for an aeronautical engine.

[0006] Prior art

[0007] The presence of a metal leading edge on a composite material blade of an aeronautical engine makes it possible to protect a composite blade from abrasion / erosion and / or during an impact from a foreign body. This is particularly the case for the fan blades of an aeronautical turbomachine which are exposed to possible ingestion of a bird, hail, ice, etc.

[0008] The manufacture of such a fan blade firstly comprises the production of a blade from a composite material comprising a fibrous reinforcement densified by a matrix generally obtained from a thermosetting or thermoplastic resin.

[0009] Once the composite material blade has been obtained, it is then necessary to assemble, on a front edge of the composite material blade, a protective metal leading edge. For this purpose, a metal foil, produced by mechanical processes such as stamping, forming or electroforming for example, is bonded to the front edge of the composite material blade. Such an operation can be carried out in a mold ensuring bonding of the metal foil.

[0010] Examples of composite material blades provided with a metal leading edge are described in particular in documents US 2007 / 092379 and US 2016 / 0167269.

[0011] Bonding the metal leading edge to the leading edge of the composite blade is a delicate operation, particularly with regard to the precise positioning of the metal leading edge on the composite blade. It may, therefore, be necessary to reposition the metal leading edge after bonding.

[0012] In addition, the metal leading edge may become damaged, particularly as a result of an event such as an impact with a foreign body, or worn, particularly after the composite blade has been in operation for a certain period of time. The metal leading edge must then be replaced.

[0013] However, once bonded, the metal leading edge cannot be removed from the composite blade without damaging the latter, due to the bonding force between the metal leading edge and the composite blade. This prevents remanufacturing and / or replacement of the metal leading edge of the composite blade.

[0014] Statement of the invention

[0015] The main aim of the present invention is therefore to propose a method of manufacturing a blade, in particular made of composite material, provided with a leading edge, in particular metallic, which does not have the aforementioned drawbacks.

[0016] According to the invention, such an aim is achieved by means of a method for manufacturing a blade, in particular made of composite material, comprising an added leading edge, in particular made of metal, comprising at least:

[0017] - a forming step, during which a blade structure, comprising at least one leading edge, is shaped; and

[0018] - a positioning step, during which the leading edge is positioned on the front edge portion of the blade structure.

[0019] More specifically, during the positioning step, the leading edge is fixed to the leading edge by means of a heat-sensitive adhesive material, in particular a heat-sensitive glue.

[0020] The use of a heat-sensitive adhesive material offers the possibility of being able to disassemble the leading edge after adhesion without damaging a material constituting the blade structure. Indeed, by heating the blade to a temperature higher than the melting temperature of the heat-sensitive adhesive material, the adhesive material loses its adhesive power. The leading edge can then be gently removed without exerting stress on the blade structure, particularly in composite material.

[0021] According to a particular characteristic of the manufacturing method according to the invention, the heat-sensitive adhesion material may have a melting temperature lower than a damage temperature of the material of the blade structure.

[0022] According to another particular characteristic of the manufacturing method according to the invention, the heat-sensitive adhesion material may have a melting point of between 90°C and 120°C.

[0023] According to another particular characteristic of the manufacturing method according to the invention, the heat-sensitive adhesion material is a neoprene glue.

[0024] The invention also relates to a method for reworking or repairing a blade, in particular made of composite material, comprising an added leading edge comprising at least:

[0025] - a heating step, during which the blade is heated to a temperature above a melting temperature of the heat-sensitive adhesion material;

[0026] - a removal step, during which the leading edge is detached from the blade; and

[0027] - a repositioning step, during which the leading edge or a new leading edge is fixed to the front edge of the blade structure.

[0028] The positioning of the leading edge can be resumed after being fixed, during the positioning step, without damaging the material constituting the blade structure. This avoids the scrapping of the blade or blade structure initially manufactured.

[0029] Similarly, when the leading edge is damaged or worn during use of the blade, it can be replaced without damaging the material constituting the blade structure, which makes it possible to extend the service life of the blade. The invention also relates to a blade made of composite material for an aeronautical engine comprising an added metal leading edge and a blade structure made of composite material comprising, in a longitudinal direction:

[0030] - a dawn foot,

[0031] - a stilt, and

[0032] - a blade body, the blade body extending:

[0033] - following the longitudinal direction, between Péchasse and a summit, and

[0034] - in a transverse direction, between a front edge and a rear edge, and

[0035] - a leading edge fixed to the front edge of the composite material blade structure.

[0036] More specifically, the blade further comprises a layer of a heat-sensitive adhesive material, including a heat-sensitive glue, present between the leading edge and the leading edge.

[0037] According to a particular characteristic of the blade of the invention, the heat-sensitive adhesion material may have a melting temperature lower than a damage temperature of the composite material of the blade.

[0038] According to another particular characteristic of the blade of the invention, the heat-sensitive adhesion material may have a melting point of between 90°C and 120°C.

[0039] According to another particular characteristic of the dawn of the invention, the heat-sensitive adhesion material is a neoprene glue.

[0040] Brief description of the drawings

[0041] The present invention will be better understood and other characteristics and advantages will become apparent upon reading the detailed description which follows, comprising embodiments given by way of illustration with reference to the appended figures, presented as non-limiting examples, which may serve to complete the understanding of the present invention and the description of its embodiment and, where appropriate, contribute to its definition, in which: [Fig. 1] Figure 1 is a schematic perspective view of a blade provided with a leading edge added in accordance with an embodiment of the invention;

[0042] [Fig. 2] Figure 2 is a sectional view along plane II-II of the blade of Figure 1; and

[0043] [Fig. 3] Figure 3 is an exploded perspective schematic view showing the assembly of a leading edge on a blade structure according to the invention.

[0044] Description of the embodiments

[0045] The invention applies to the production of blades, in particular made of composite material, for an aeronautical engine having a leading edge, in particular a metallic one, such as for example fan blades.

[0046] Figure 1 is a schematic perspective view of a blade 30 provided with a leading edge 20 added in accordance with one embodiment of the invention.

[0047] More particularly, FIG. 1 illustrates a blade 30 which comprises a blade structure 10, in particular made of composite material, comprising, in a longitudinal direction D L :

[0048] - a dawn foot 11, and

[0049] - a blade body 13 extending, in a transverse direction D T, between :

[0050] - a leading edge 20 and

[0051] - a trailing edge 132.

[0052] The blade structure 10 may also comprise a stilt 12.

[0053] The blade body 13 also comprises an intrados face 133 and an extrados face 134, extending respectively between the leading edge 20 and the trailing edge 132 on either side of the blade body 13 in an orthogonal direction D. o , forming an orthonormal reference frame with the longitudinal direction D L and the transverse direction D T .

[0054] The blade body 13 may also include a tip 135.

[0055] The leading edge 20, in particular made of a foil made of metallic material, is fixed to all or part of a front edge 136 of the blade body 13.

[0056] The trailing edge 132 consists of a rear edge 14 of the blade body 13. According to a particular embodiment, with the exception of the leading edge 20, the blade 30 is made of composite material.

[0057] Figure 2 is a sectional view along plane II-II of the blade 30 of Figure 1.

[0058] As illustrated in Figure 2, the leading edge 20 is positioned on the front edge 136 of the blade body 13 and fixed, in particular by adhesion, in particular by gluing, by means of a layer 40 or a film 40 of an adhesion material.

[0059] According to the invention, the adhesion material may be a heat-sensitive adhesion material.

[0060] By "heat-sensitive adhesive material" is meant here an adhesive material capable of losing its adhesive power and / or its rigidity from a given temperature, also called melting temperature.

[0061] According to a particular embodiment, the adhesion material is an adhesive, in particular a heat-sensitive adhesive.

[0062] A method of manufacturing the blade 30 comprises at least one forming step, during which a blade structure 10, in particular made of composite material, is shaped.

[0063] In the case of a blade structure made of composite material, the blade structure 10 is obtained during the manufacturing step from a fibrous reinforcement densified by a matrix.

[0064] By "composite material blade structure" is meant here a blade body, comprising most of the constituent parts of the final blade 30, in particular the blade root 11 and the blade body 13, with the exception of the leading edge 20, consisting of a foil, in particular metallic, attached to the blade structure 10 in composite material, entirely in composite material.

[0065] The blade structure 10 made of composite material is manufactured from a fiber preform that can be obtained in various ways known to those skilled in the art. Typically, the preform can be obtained directly by three-dimensional weaving of threads, formed for example of carbon fibers, or by draping two-dimensional fiber fabrics.

[0066] The manufacture of a fan blade 30 made of composite material obtained from a fiber reinforcement produced by three-dimensional weaving and densified by a matrix is ​​described in particular in document US 2005 / 084377. In the example described here, the fan blade preform 30 is obtained by three-dimensional weaving of carbon fiber threads.

[0067] In a known manner, the blade structure preform 10 is then impregnated with a liquid composition containing a precursor of the matrix material. The precursor is usually in the form of a polymer, such as a resin, possibly diluted in a solvent.

[0068] The preform is placed in a mold that can be closed in a sealed manner with a housing having the shape of the molded blade structure 10 and which can in particular have a twisted shape corresponding to the final shape of the blade body with the desired aerodynamic profile.

[0069] Then the mold is closed and the liquid matrix precursor, for example an epoxy resin, is injected throughout the mold to impregnate the entire fibrous part of the preform.

[0070] The impregnation of the fiber blade preform can be carried out in particular by a transfer molding process, also designated by the acronym "RTM" for "Resin Transfer Molding" in English.

[0071] A transformation of the precursor into a matrix, for example by polymerization, is carried out by heat treatment, generally by heating the mold, after removal of any solvent and crosslinking of the polymer, the preform being always maintained in the mold having a shape corresponding to that of the desired aerodynamic profile structure.

[0072] The matrix can be obtained in particular from epoxy resins, such as the high-performance epoxy resin sold under the reference PR 520 by the company CYTEC, or from liquid precursors of carbon or ceramic matrices.

[0073] In the case of formation of a carbon or ceramic matrix, a heat treatment consists of pyrolyzing an organic precursor to transform the organic matrix into a carbon or ceramic matrix depending on the precursor used and the pyrolysis conditions.

[0074] For example, liquid carbon precursors may be relatively high coke resins, such as phenolic resins, while liquid ceramic precursors, particularly silicon carbide (SiC), may be polycarbosilane (PCS) or polytitanocarbosilane (PTCS) or polysilazane (PSZ) type resins.

[0075] Several consecutive cycles, from impregnation to heat treatment, can be carried out to achieve the desired degree of densification.

[0076] Afterwards, a part thus obtained is demolded. Finally, the part is trimmed to remove excess resin and chamfers can be machined.

[0077] No further machining is necessary since, as the part is cast, it meets the required dimensions.

[0078] The blade structure 10, in particular made of composite material, is thus obtained.

[0079] Figure 3 is a schematic exploded perspective view showing the assembly of the leading edge 20 on the blade structure 10 according to the invention.

[0080] The blade structure 10 comprises, as illustrated in FIG. 3, the blade root 11, and the blade body 13. The blade structure 10 may also comprise Péchasse 12.

[0081] The blade body 13 extending between the blade root 11, more particularly between Péchasse 12, and the top 150 of the blade body 13.

[0082] The blade body 13 comprises the front edge 136 of the blade body 13 of the blade 30.

[0083] The front edge 136 is intended to receive a foil, in particular metallic, in order to form the leading edge 20 of the final blade.

[0084] As illustrated in Figure 3, the leading edge 20 comprises:

[0085] - an internal wall 201, intended to be fixed on the front edge 136 of the blade structure 10 and

[0086] - an external wall 202, defining the leading edge profile 20 of the final blade 30.

[0087] The leading edge 20 further comprises a nose portion 203 from which two fins 204 and 205 extend.

[0088] The manufacture of the blade 30 comprises a positioning step consisting of positioning the leading edge 20 on the blade structure 10, in particular by adhesion, in particular by bonding. More precisely, as illustrated in FIG. 3, the leading edge 20 is docked on the front edge 136 present on the blade body 13 of the blade structure 10 with interposition of the film 40 or the layer 40 of the adhesion material between the internal wall 201 of the leading edge 20 and the front edge 136 of the blade structure 10.

[0089] The layer 40 of the adhesion material present between the leading edge 20 and the front edge 136 of the blade structure 10 can be produced in different ways. It can in particular correspond to the adhesion material placed in a sandwich between the internal wall 201 of the leading edge 20 and the front edge 136 of the blade structure 10, the whole, once assembled, being placed in a heated mold to activate, in particular to polymerize, the adhesive power of the layer 40 of the adhesion material.

[0090] The layer 40 of the adhesion material can also be deposited directly on the internal wall 201 of the leading edge 20 and / or on the front edge 136 of the blade structure 10, the assembly being carried out in the mold, capable of exerting pressure on the leading edge 20 and the blade structure 10 to be assembled, and possibly of carrying out a heat treatment of the adhesion, in particular bonding.

[0091] The step of positioning the leading edge 20 on the blade structure 10 is notably described in the document FR 2 992 887 A1.

[0092] According to the invention, a heat-sensitive adhesive material, in particular a heat-sensitive glue, is used to fix the leading edge 20 to the blade structure 10, in particular made of composite material.

[0093] As previously indicated, the heat-sensitive adhesive material is capable of losing its adhesive power and / or its rigidity from a determined temperature, also called the melting temperature.

[0094] The melting temperature of the heat-sensitive adhesion material is preferably lower than a damage temperature of the blade structure 10, in particular a damage temperature of the composite material of the blade structure 10.

[0095] The damage temperature is the temperature at which the composite material begins to thermally degrade. At such a damage temperature, the composite material may show signs of softening and / or a loss of mechanical properties. In addition, at such a damage temperature, the composite material may show a weakening of the interface between the fibers and the matrix, reducing the strength of the composite material. Such a damage temperature depends on the composite material considered.

[0096] Furthermore, the melting temperature is also preferably higher than the temperatures encountered in operation by the blade 30 in order to avoid possible problems with the holding of the leading edge 20 during use of the blade 30.

[0097] Thus, the melting temperature of the heat-sensitive adhesive material is preferably between 90°C and 120°C.

[0098] In particular, the heat-sensitive adhesive material may be a neoprene glue.

[0099] After positioning the leading edge 20, the blade 30 of FIG. 1 is obtained.

[0100] The use of a heat-sensitive adhesion material according to the invention finds an advantageous application in a resumption of manufacture of the blade 30, in particular made of composite material, with a leading edge 20, in particular metallic, and / or the replacement of the leading edge 20 during maintenance of the blade 30 in service.

[0101] Indeed, during the manufacture of the blade 30, like that previously described, it is possible that, during the positioning step, the blade 30 is poorly positioned or that the leading edge 20 is damaged after positioning.

[0102] In such a case, according to the invention, the blade 30 is then heated to a temperature above the melting temperature of the heat-sensitive adhesive material. Once the melting temperature is reached, the leading edge 20 to be repositioned can be detached little by little without damaging the blade structure 10, in particular the composite material of the blade structure 10.

[0103] The leading edge 20 is then repositioned or replaced, which makes it possible not to scrap the blade 30 and / or the blade structure 10 initially manufactured.

[0104] Likewise, once in service, the leading edge 20 of the blade 30 may be damaged following an event, such as an impact with a foreign body, or worn after a certain time of operation of the blade 30. In such a case, according to the invention, the blade 30 is then heated to a temperature above the melting temperature of the heat-sensitive adhesion material. Once the melting temperature is reached, the damaged and / or worn leading edge 20 can be detached little by little without damaging the blade structure 10, in particular the composite material of the blade structure 10.

[0105] The leading edge 20 is then replaced, which extends the life of the blade 30.

Claims

Claims

1. Method for reworking or repairing a blade (30), in particular made of composite material, comprising a leading edge (20) fixed to a front edge (136) of a blade structure (10) by means of a heat-sensitive adhesive material comprising at least: - a heating step, during which the blade (30) is heated to a temperature above a melting temperature of the heat-sensitive adhesion material; - a removal step, during which the leading edge (20) is detached from the blade (30); and - a repositioning step, during which the leading edge (20) or a new leading edge (20) is fixed to the front edge (136) of the blade structure (10).

2. The method of claim 1, wherein the heat-sensitive adhesion material has a melting temperature below a damage temperature of the composite material of the blade (30).

3. The method of claim 1, wherein the heat-sensitive adhesion material has a melting point of between 90°C and 120°C.

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

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