Method of manufacturing a propeller blade or fin with an insert bonded in the dry preform

Abstract

The invention relates to a method for manufacturing a propeller blade or a fin, the method comprising: - producing a fibrous blank of a structure having an aerodynamic profile and comprising an internal shell; - inserting at least one insert into the internal shell, and a bonding film is interposed between the insert and the internal shell of the fibrous blank, to obtain a fibrous preform (200); - holding the fibrous preform (200) in a mould cavity (301) of an injection tool (300); - injecting a resin (380) into the mould cavity (301) containing the fibrous preform (200), and transforming the resin into a matrix using a heat treatment. The method also comprises, after holding the fibrous preform (200) in the mould cavity (301) and before injecting the resin (380) into the fibrous preform, a step of pre-consolidation of the bonding film, the pre-consolidation step comprising at least the application of a consolidation pressure in the mould cavity (301).

Description

Technical Field

[0001] This invention relates to the field of propeller blades or fins for aircraft (such as propeller blades or fins present on turbines). Background Technology

[0002] To obtain lighter propeller blades or fins, it is known to produce propeller fins made of composite materials, that is, to produce structural parts by means of fiber reinforcements densified from a matrix.

[0003] Document US 2005 / 0084377 describes a method for manufacturing turbine blades made of integral composite materials, which are produced by three-dimensional weaving of fiber preforms and densification of the preforms with a matrix. This method allows for the production of blades with very high mechanical resistance (especially relative to impact or collision) without the risk of delamination. However, manufacturing large integral propeller blades or airfoils using this technology can be challenging.

[0004] A manufacturing method has been developed to produce blades or fins by introducing one or more inserts into a dry fiber preform.

[0005] For example, document US 2013 / 0017093 describes the production of propeller blades from an airfoil fiber structure, with a portion of the spar inserted into the airfoil fiber structure.

[0006] Bonding inserts in dry fiber preforms is a delicate process, particularly regarding controlling the bonding interface. If the adhesive layer is not uniformly distributed between the preform and the insert, the bond quality deteriorates, leading to a reduction in mechanical strength. Because dry fiber preforms are inherently porous, some adhesive film permeates through the preform under capillary action, resulting in an uneven adhesive film, which adversely affects the mechanical properties of the part. Summary of the Invention

[0007] Therefore, it is desirable to propose a solution for producing aircraft propeller blades or fins that ensures uniform bonding across the entire interface between the insert and the fiber preform.

[0008] Therefore, the present invention proposes a method for manufacturing turbine propeller blades or airfoils, the method comprising: - Producing airfoil-shaped fiber preforms, including an internal shell, through three-dimensional weaving of yarns; - Insert at least one insert into the inner housing, wherein an adhesive film is located between the insert and the inner housing of the fiber preform to obtain a fiber preform; - Hold the fiber preform in the mold cavity of an injection tool that has the shape of a propeller blade or winglet to be manufactured; - Resin is injected into a mold cavity containing a fiber preform, and the resin is transformed into a matrix through heat treatment; Its characteristic is that the method further includes a step of pre-consolidating the adhesive film after the fiber preform is held in the mold cavity and before the resin is injected into the fiber preform, the pre-consolidation step including at least applying consolidation pressure in the mold cavity.

[0009] Applying pressure in the mold cavity allows the pressure on the adhesive film to be maintained through the dry fiber preform, thereby preventing the adhesive from flowing into the pores of the fiber preform by capillary action before resin injection.

[0010] A particular feature of the method according to the invention is that consolidation pressure is applied within the mold cavity by injecting pressurized inert gas into the cavity. This allows the risk of pores being generated primarily in the adhesive and potentially in the resin during injection to be avoided.

[0011] Another particular feature of the method according to the invention is that the adhesive film comprises a thermosetting epoxy resin layer.

[0012] Another particular feature of the method according to the invention is that the pre-consolidation step of the adhesive film further includes partially polymerizing the adhesive film by applying heat treatment. This partially stabilizes the bond between the insert and the fiber preform before resin injection. The adhesive film is preferably partially polymerized at a ratio between 20% and 50%. This allows for optimization of the insert's adhesion by performing another partial polymerization of the adhesive film during injection and final curing of the part.

[0013] Another particular feature of the method according to the invention is that the adhesive film also includes a fiber interface texture. The interface texture allows for calibration of the thickness of the adhesive interface between the insert and the fiber preform.

[0014] Another particular feature of the method according to the invention is that the material of the at least one insert is selected from one of the following materials: metallic materials, polymeric materials including a sealing surface coating, or composite materials. Attached Figure Description

[0015] [ Figure 1 ] Figure 1 This is a perspective view of an aircraft propeller blade according to an embodiment of the present invention; [ Figure 2 ] Figure 2 It shows the manufacturing process. Figure 1 A schematic diagram of the 3D weaving of a fiber preform for the airfoil structure of a propeller blade; [ Figure 3A ] Figure 3A It is formed Figure 1 A magnified partial cross-sectional view of a set of yarn layers of the blank; [ Figure 3B ] Figure 3B It is formed Figure 1 Another partial cross-sectional view of a set of yarn layers of the blank at an enlarged scale; [ Figure 4 ] Figure 4 It is shown Figure 1 Exploded view of the production of preforms for propeller blades; [ Figure 5 ] Figure 5 It shows the injection tool and Figure 4 An exploded three-dimensional diagram showing the placement of the preform within it; [ Figure 6 ] Figure 6 This illustrates an embodiment of the present invention. Figure 5 A three-dimensional schematic diagram of the injection tool closing during the pre-curing step of the adhesive film; [ Figure 7 ] Figure 7 It is shown Figure 5 A three-dimensional schematic diagram of the injection tool closing during the resin injection step; [ Figure 8 ] Figure 8 An example of the evolution of operating parameters during the pre-consolidation step of the adhesive film according to the invention is shown. Detailed Implementation

[0016] This invention is generally applicable to various types of propeller blades or fins used in aircraft engines. Advantageously, but not exclusively, it is applicable to large propeller blades or fins to be integrated into pivoting or variable-pitch systems. Such propeller blades or fins typically have a root with small space requirements (compact shape) and good resistance to tension, bending forces, and circumferential compressive forces. Blades according to the invention can be specifically configured for ducted rotors such as fan blades, or for non-ducted rotors such as those used in aero engines known as open rotor engines.

[0017] In the remainder of the specification, an exemplary embodiment of the method of the invention is described with respect to the manufacture of turboprop engine blades. However, the exemplary embodiments are also applicable to the manufacture of propeller blades for aircraft turbines.

[0018] Figure 1A blade 10 intended for mounting on an aircraft turboprop engine is presented. The blade 10 includes: an airfoil 20, known per se for forming the aerodynamic portion of the blade, a root 33 formed by a thicker portion (e.g., having a bulb-shaped cross-section) and extending from a strut 34. The airfoil 20 has a curved profile in cross-section, with a variable thickness between its leading edge 20a and its trailing edge 20b. The propeller blade 10 includes a sparsity 30 comprising a first portion 31 and a second portion 32, the first portion 31 extending externally to the airfoil 20 and including the root 33 and the strut 34, and the second portion 32 disposed internally to the airfoil 20.

[0019] Figure 2 The fiber preform 100 for forming the airfoil structure of the blade is shown in a very schematic manner.

[0020] like Figure 2 As illustrated, the fiber preform 100 is obtained by three-dimensional (3D) weaving using a jacquard loom in a known manner, on which bundles of warp yarns 101 or strands are arranged in multiple layers, each layer having hundreds of yarns, and these warp yarns are interconnected by weft yarns 102.

[0021] In the example shown, the 3D weaving is double rib weaving. "Double rib" weaving refers to a weaving in which each layer of weft yarns is interconnected with multiple layers of warp yarns, and all yarns in the same weft row have the same movement in the weaving plane.

[0022] Other known types of three-dimensional weaving can be used, such as those described in particular in document WO 2006 / 136755.

[0023] Fiber blanks can be woven from carbon fibers or ceramic yarns (such as silicon carbide).

[0024] When weaving fiber preforms with varying thickness and width, a certain number of warp yarns are left unwoven, which allows for defining the desired, continuously variable profile and thickness of the preform 100. An example of scalable 3D weaving is described in document EP 1526285, which specifically makes it possible to change the thickness of the preform between a first edge used to form the leading edge and a smaller second edge used to form the trailing edge.

[0025] During weaving, within the fiber blank, between two consecutive warp layers, and in the non-interconnected region 104 ( Figure 4 A non-interconnected structure 103 is formed on it. Figure 2 The non-interconnected region 104 allows for the arrangement of an internal shell 104a within the fiber preform 100 for introducing inserts (here, spars) to form a preform of the airfoil structure.

[0026] exist Figure 3A and Figure 3B The blank 100 is schematically shown using a three-dimensional weaving pattern with double rib weaving. Figure 3A This is an enlarged partial view of two consecutive warp cross-sectional planes in the portion of blank 100 that does not have a non-interconnected structure (that is, in the region of the blank outside the non-interconnected region 104). Figure 3B Two consecutive warp cross-sectional planes are shown in a portion of the blank 100 having a non-interconnected structure 103 forming a non-interconnected region 104.

[0027] In this example, the blank 100 includes six layers of warp yarns 101 extending along the X direction. Figure 3A In this process, the six warp layers are interconnected by weft yarns T1 to T5. Figure 3B In this structure, the three warp yarns 101 forming a set of yarn layers 105 are interconnected by two weft yarns T1 and T2, and the three warp yarns forming a set of yarn layers 106 are interconnected by two weft yarns T4 and T5. In other words, the fact that weft yarns T1 and T2 do not extend into yarn layer 106 and weft yarns T4 and T5 do not extend into yarn layer 105 ensures a non-interconnected structure 103 that separates the warp yarn layers 105 and 106 from each other.

[0028] At the end of the weaving ( Figure 2 For example, using pressurized water jets to cut warp and weft yarns at the boundaries of the knitted fabric to extract... Figure 4 The dry preform 100 shown is derived from 3D weaving and has not undergone any forming process. Non-interconnected regions 104 arranged during weaving allow the formation of two independently woven portions 110 and 111, which define an inner shell 104a within the preform 100. The two portions 110 and 111 form the skins 21 and 22 of the airfoil structure 20. The inner shell 104a opens at the lower edge 100c and rear edge 100b of the preform 100. The leading edge 100a of the fiber preform 100 connects the two portions 110 and 111 and forms the leading edge 20a of the airfoil structure 20 of the blade 10, while the rear edge 100b of the preform 100 corresponds to the rear edge 20b used to form the airfoil structure. Figure 1 ( ) part.

[0029] According to the present invention, the manufacture of the blade includes using insert 40 ( Figure 4 ), here, it corresponds to the wing beam.

[0030] Insert 40 includes a first portion 41 and a second portion 42. The first portion 41, corresponding to the first portion 31 of the spar 30, includes a root 33 and a support 34 for forming the blade 10, respectively. Figure 1The spar 30 has a protruding portion 411 and a reduced thickness portion 412. The reduced thickness portion 412 extends from the second portion 42, which corresponds to the second portion 32 of the spar 30.

[0031] In the example described here, insert 40 is made of a metallic material (e.g., titanium).

[0032] The adhesive film 50 is deposited on the entire surface of the second portion 42 of the insert (which corresponds to the portion of the insert that is introduced into the inner housing 104a of the dry fiber preform 100). Thus, after the insert is inserted into the inner housing of the fiber preform, the adhesive film is located between the insert and the wall of the inner housing 104a.

[0033] The adhesive film includes a thermosetting epoxy resin layer, which may correspond, for example, to epoxy resin EA914 manufactured by Hysol®, adhesive film AF191 manufactured by 3M®, adhesive film FM300 manufactured by Cytec®, or epoxy resin EA9396 manufactured by Hysol®.

[0034] exist Figure 4 In this process, the dry fiber preform 100 is formed by introducing the second portion 42 of the insert 40, covered with an adhesive film 50, into the inner housing 104a. The resulting blade preform 200 includes an airfoil preform portion 211 along the longitudinal direction DL, which is formed by the dry fiber preform 100 in the inner housing 104, with the second portion 42 of the insert 40 inserted from the inner housing. Therefore, the adhesive film 50 is positioned between the second portion 42 and the dry fiber preform 100. The airfoil preform portion 211 extends along the transverse direction DT between the leading edge portion 211a and the trailing edge portion 211b.

[0035] like Figure 5 As shown, the blade preform 200 is placed in an injection tool 300, which includes a first shell 310 and a second shell 320. The first shell 310 includes a first molding surface 311 at its center, which partially corresponds to the shape and size of the blade to be produced. The second shell 320 includes a second molding surface 321 at its center, which partially corresponds to the shape and size of the blade to be produced.

[0036] like Figure 6 As shown, once the tool 300 is closed, the first forming surface 311 of the first shell 310 and the second forming surface 321 of the second shell 320 together define the mold cavity 301, which has the shape of the blade to be produced, and the preform 200 is held in the mold cavity 301.

[0037] According to the invention, the step of pre-consolidating the adhesive film is then performed. In the example described herein and as... Figure 6 As shown, the pre-consolidation step includes applying consolidation pressure in the mold cavity 301. For this purpose, a pressurized gas flow 360 is injected into the mold cavity through an injection port 313 in the first housing 310 of the tool 300. The pressure inside the mold cavity 301 can be adjusted via an exhaust port 323 in the second housing 320.

[0038] Applying pressure in mold cavity 301 allows pressure to be maintained on the adhesive film through the dry fiber preform, thereby preventing adhesive from flowing into the pores of the preform. The pressure applied to the mold cavity during the pre-consolidation step can be between 1 bar and 3 bar. The gas flow injected into port 313 to apply pressure in the mold cavity can be air or an inert gas such as nitrogen to limit the risk of porosity formation.

[0039] During the pre-consolidation step, the application of consolidation pressure can be combined with partial polymerization of the adhesive film. In this case, a heat treatment cycle is further applied to the preform held in the injection tool. Partial polymerization of the adhesive film allows for increased creep resistance. In the example described here, the injection tool 300 also includes a lower portion 340 and an upper portion 350 therebetween, with a first housing 310 and a second housing 320 disposed therebetween, the lower portion 340 and the upper portion 350 being equipped with heating devices. Figure 6 (Not shown in the image).

[0040] The duration and temperature steps of the applied thermal cycle determined the polymerization level of the adhesive. Figure 8 This illustrates the pre-consolidation step of the adhesive film, which combines pressure application and partial polymerization thermal cycling (“ Figure 8 An example of the operating parameters used in the "insertion cycle" is shown. In this example, the adhesive is AF191 adhesive film manufactured by 3M®, and the pre-curing step is carried out over a period of approximately 1 hour, during which the pressure in the mold cavity is brought to a value between 1 bar and 3 bar, while the preform is exposed to a temperature of 110°C after a temperature rise. This allows for a polymerization rate (α1) of 25% for the adhesive film.

[0041] When thermal cycling is applied during the pre-curing step, the adhesive film is partially polymerized at a rate preferably between 20% and 50%. This allows for optimization of insert adhesion by performing additional polymerization of the adhesive film during injection and final curing of the part.

[0042] Then, as Figure 7As shown, the fibrous portion of the preform (here, the formed fibrous preform) is densified. Densification of the fibrous portion of the preform involves filling its pores with a material constituting the matrix. This densification is performed using a liquid process (CVL) in a manner known per se. The liquid process involves impregnating the preform with a liquid composition containing a precursor of the matrix material. This precursor is typically in polymer form, such as a high-performance epoxy resin, and may be diluted in a solvent.

[0043] The transformation of the precursor into the matrix, i.e. its polymerization, is carried out by heat treatment, usually after removing any solvents and polymer crosslinking, by heating the injection tool. The preform is always held in the mold cavity, the shape of which corresponds to the shape of the part to be produced.

[0044] In the case of forming a carbon or ceramic matrix, heat treatment involves pyrolyzing the precursor to transform the matrix into a carbon or ceramic matrix, depending on the precursor used and the pyrolysis conditions. For example, liquid ceramic precursors (especially SiC) can be polycarbosilane (PCS), polytitanium carbosilane (PTCS), or polysilazane (PSZ) resins, while liquid carbon precursors can be resins with a relatively high coke ratio, such as phenolic resins. Several consecutive cycles from impregnation to heat treatment can be performed to achieve the desired degree of densification.

[0045] According to one aspect of the invention, particularly in the case of forming an organic matrix, the densification of fiber preforms can be achieved using a known resin transfer molding (RTM) method. According to the RTM method, the fiber preform is placed in a mold having the external shape of the part to be produced. A thermosetting resin is injected into the internal space of the mold containing the fiber preform. Typically, a pressure gradient is established in this internal space between the resin injection point and the resin discharge orifice to control and optimize the impregnation of the preform with the resin.

[0046] like Figure 7 As shown, and according to the RTM method, resin 380 (e.g., thermosetting resin) is injected via injection port 313 of the first shell 310 into the mold cavity 301 occupied by the preform 200. The port 323 of the second shell 320 is connected to a discharge pipe maintained under pressure. Figure 7 (Not shown in the diagram). This configuration allows a pressure gradient to be established between the lower portion of the injected resin in the preform 200 and the upper portion of the preform located near the outlet 323. In this way, the resin 360 injected essentially at the level of the lower portion of the preform will gradually permeate the entire fibrous portion of the preform by circulating it throughout the preform until the outlet 323, with the remaining resin discharged through the outlet 323. Of course, the first housing 310 and the second housing 320 of the tool 300 may accordingly include a number of injection ports and a number of discharge ports.

[0047] The resin used can be, for example, an epoxy resin with a temperature rating of 180°C (the highest temperature that can be withstood without loss of properties). Resins suitable for the RTM method are well known. They preferably have low viscosity to facilitate their incorporation into the fibers. The selection of the resin's temperature rating and / or chemical properties is determined based on the thermomechanical loads that the part must withstand. Once the resin is infused into the entire reinforcement, it is polymerized by heat treatment according to the RTM method.

[0048] After injection and polymerization, the blades are demolded. Finally, the blades can be trimmed to remove excess resin and machined with chamfers. No further machining is required; once the part is molded, it meets the required dimensions. Thus, the desired result is obtained. Figure 1 Leaf 10.

[0049] The densification method described above allows the production of propeller blades or fins made primarily of organic matrix composite (OMC), carbon matrix composite (C / C), and ceramic matrix composite (CMC) materials from the fiber preforms of the present invention.

[0050] According to an optional feature of the method of the invention, the adhesive film may further include a fibrous interface texture. The fibrous interface texture is a thin layer whose thickness allows for defining or calibrating the thickness of the interface (adhesive joint) between the insert and the portion of the fibrous preform that contacts the adhesive film. The thickness of the fibrous interface texture is preferably less than 1 mm. The fibrous interface layer can have various types of textures, such as, in particular, Marquise yarn, two-dimensional woven fabrics, knitted fabrics, felted articles, mesh structures, braids, or mats.

Claims

1. A method for manufacturing turbine propeller blades or airfoils (10), the method comprising: - A filament blank (100) with an airfoil structure is produced by three-dimensional weaving of yarn, the blank including an inner shell (104a). - Insert at least one insert (40) into the inner housing (104a) and an adhesive film (50) is placed between the insert and the inner housing of the fiber preform to obtain a fiber preform (200). - The fiber preform (200) is held in the mold cavity (301) of the injection tool (300) having the shape of the propeller blade or winglet to be manufactured. - Resin (380) is injected into a mold cavity (301) containing the fiber preform (200), and the resin is transformed into a matrix by heat treatment. The method is characterized by further comprising: a step of pre-consolidating the adhesive film after holding the fiber preform (200) in the mold cavity (301) and before injecting resin (380) into the fiber preform, the step comprising at least applying consolidation pressure in the mold cavity (301).

2. The method according to claim 1, wherein, The consolidation pressure is applied in the mold cavity by injecting pressurized inert gas into the mold cavity (301).

3. The method according to claim 1 or 2, wherein, The adhesive film (50) includes a thermosetting epoxy resin layer.

4. The method according to claim 1, wherein, The pre-consolidation step of the adhesive film (50) further includes partially polymerizing the adhesive film by applying heat treatment.

5. The method according to claim 4, wherein, The adhesive film is partially polymerized at a ratio between 20% and 50%.

6. The method according to claim 1, wherein, The adhesive membrane also includes a fiber interface texture.

7. The method according to claim 1, wherein, The material of the at least one insert (40) is selected from one of the following: metallic materials, polymeric materials including a sealing surface coating, or composite materials.

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