Method for manufacturing a propeller blade or vane with bonding of an insert in a dry preform
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-05-15
- Publication Date
- 2026-03-25
AI Technical Summary
Manufacturing large propeller blades with uniform bonding of inserts in a dry fibrous preform is challenging due to non-homogeneous adhesive distribution, leading to reduced mechanical strength and performance.
A method involving three-dimensional weaving of a fibrous blank with an internal housing, insertion of an insert with an adhesive film, pre-consolidation under pressure and heat to stabilize the adhesive, and subsequent resin injection to form a matrix, ensuring uniform bonding and preventing adhesive penetration into the preform's porosity.
This method ensures consistent and strong bonding between the insert and the fibrous preform, enhancing mechanical performance and preventing porosity issues during resin injection, resulting in high-strength propeller blades.
Smart Images
Figure FR2024050623_21112024_PF_FP_ABST
Abstract
Description
[0001] Description
[0002] Title of the invention: Method for manufacturing a propeller blade or vane with gluing of an insert in a dry preform
[0003] Technical Field
[0004] The present invention relates to the field of propeller blades or vanes for aircraft such as those present on turbomachines.
[0005] Prior art
[0006] In order to obtain lighter propeller blades or blades, it is known to produce propeller blades from composite material, that is to say by producing structural parts with fibrous reinforcement densified by a matrix.
[0007] Document US 2005 / 0084377 describes a method for manufacturing a turbomachine blade from a monolithic composite material, the blade being manufactured by three-dimensional weaving of a fiber preform and densification of the preform by a matrix. This method makes it possible to obtain blades with very high mechanical strength, particularly with respect to shocks or impacts, without risk of delamination. However, the manufacture of large monolithic propeller blades or vanes using this technique can prove difficult.
[0008] Manufacturing processes have been developed for manufacturing blades or vanes with the introduction of one or more inserts into a dry fiber preform.
[0009] Document US 2013 / 0017093 describes, for example, the production of a propeller blade from a fiber structure with an aerodynamic profile into which part of a spar is introduced.
[0010] Bonding the insert(s) into the dry fiber preform is a delicate operation, particularly with regard to controlling the bonding interface. If the layer of adhesive material is not uniformly present between the preform and the insert(s), the quality of the bonding is degraded, which results in a reduction in the mechanical strength. Since the dry fiber preform is porous by nature, part of the adhesive film penetrates into the preform by capillarity, which leads to a non-homogeneous adhesive film which can impair the mechanical performance of the part. Disclosure of the invention
[0011] It is therefore desirable to be able to offer a solution for the production of aircraft propeller blades or vanes that ensures uniform bonding across the entire interface between an insert and a fiber preform.
[0012] To this end, the present invention proposes a method of manufacturing a turbomachine propeller blade or vane, the method comprising:
[0013] - the production of a fiber blank of an aerodynamically profiled structure by three-dimensional weaving of threads, the blank comprising an internal housing,
[0014] - the insertion of at least one insert into the internal housing with the interposition of an adhesive film between the insert and the internal housing of the fiber blank so as to obtain a fiber preform,
[0015] - holding the fiber preform in a molding cavity of an injection tool having the shape of the blade or propeller blade to be manufactured,
[0016] - injecting a resin into the molding cavity containing the fiber preform and transforming the resin into a matrix by heat treatment, characterized in that the method further comprises, after maintaining the fiber preform in the molding cavity and before injecting the resin into the fiber preform, a step of pre-consolidating the adhesive film comprising at least the application of a consolidation pressure in the molding cavity. The application of pressure in the molding cavity makes it possible to maintain pressure on the adhesive film through the dry fiber blank and thus prevent the adhesive from flowing by capillarity into the porosity of the fiber blank before the injection of the resin.
[0017] According to a particular characteristic of the method of the invention, the application of the consolidation pressure in the molding cavity is carried out by injecting an inert gas under pressure into the molding cavity. This makes it possible to avoid the risk of porosity mainly in the adhesive and possibly in the resin during its injection.
[0018] According to another particular characteristic of the method of the invention, the adhesive film comprises a layer of thermosetting epoxy resin.
[0019] According to another particular characteristic of the method of the invention, the step of preconsolidating the adhesive film further comprises the partial polymerization of the adhesive film by applying a heat treatment. This partially stabilizes the bonding between the insert and the fiber blank before injecting the resin. The adhesive film is preferably partially polymerized at a rate of between 20% and 50%. This makes it possible to optimize the bonding of the insert by carrying out the other part of the polymerization of the adhesive film during the injection and final curing of the part.
[0020] According to another particular characteristic of the method of the invention, the adhesive film further comprises a fibrous interface texture. The interface texture makes it possible to calibrate the thickness of the bonding interface between the insert and the fibrous blank.
[0021] According to another particular characteristic of the method of the invention, the material of said at least one insert is chosen from one of the following materials: metallic material, composite material or polymer comprising a waterproof surface coating.
[0022] Brief description of the drawings
[0023] [Fig. 1] Figure 1 is a perspective view of an aircraft propeller blade in accordance with one embodiment of the invention,
[0024] [Fig. 2] Figure 2 is a schematic view illustrating the 3D weaving of a fiber blank for the manufacture of an aerodynamic profile structure of the propeller blade of Figure 1,
[0025] [Fig. 3A] Figure 3A is an enlarged partial sectional view of a set of layers of wires forming the blank of Figure 1,
[0026] [Fig. 3B] Figure 3B is another enlarged partial sectional view of a set of layers of wires forming the blank of Figure 1,
[0027] [Fig. 4] Figure 4 is an exploded view showing the production of a preform of the propeller blade of Figure 1,
[0028] [Fig. 5] Figure 5 is an exploded schematic perspective view showing an injection tool and the placement of the preform of Figure 4 therein, [Fig. 6] Figure 6 is a schematic perspective view showing the injection tool of Figure 5 closed during a pre-consolidation step of the adhesive film in accordance with one embodiment of the invention,
[0029] [Fig. 7] Figure 7 is a schematic perspective view showing the injection tooling of Figure 5 closed during a resin injection step,
[0030] [Fig. 8] Figure 8 shows an example of the evolution of operating parameters during a pre-consolidation step of an adhesive film according to the invention.
[0031] Description of the embodiments
[0032] The invention applies generally to different types of propeller blades or vanes used in aircraft engines. The invention finds an advantageous but not exclusive application in large propeller blades or vanes which are intended to be integrated into pivoting or variable pitch systems. Such propeller blades or vanes are generally provided with a root having both a small footprint (compact shape) and good resistance to tensile, bending and circumferential compression forces. The vane according to the invention may in particular constitute a vane for shrouded moving wheels such as fan blades or a vane for unshrouded moving wheels as in so-called "open rotor" aeronautical engines.
[0033] In the remainder of the description, an example of implementation of the method of the invention is described in relation to the manufacture of a blade for a turboprop. However, the example embodiment also applies to the manufacture of a turbomachine propeller blade for aircraft.
[0034] Figure 1 shows a blade 10 intended to be mounted on an aircraft turboprop which comprises, in a manner well known per se, an aerodynamic profile structure 20 intended to form the aerodynamic part of the blade, a root 33 formed by a part of greater thickness, for example with a bulb-shaped section, extended by a stilt 34. The aerodynamic profile structure 20 has in cross section a curved profile of variable thickness between its leading edge 20a and its trailing edge 20b. The propeller blade 10 comprises a spar 30 comprising a first part 31 extending outside the aerodynamic profile structure 20 and comprising the root 33 and stilt 34 and a second part 32 arranged inside the aerodynamic profile structure 20.
[0035] Figure 2 shows very schematically a fiber blank 100 intended to form the fiber preform of the aerodynamic profile structure of the blade.
[0036] The fibrous blank 100 is obtained, as schematically illustrated in Figure 2, by three-dimensional (3D) weaving carried out in a known manner using a jacquard-type loom on which a bundle of warp threads 101 or strands has been arranged in a plurality of layers of several hundred threads each, the warp threads being linked by weft threads 102.
[0037] In the example shown, the 3D weave is an interlock weave. An interlock weave here means a weave pattern in which each layer of weft yarns binds together multiple layers of warp yarns, with all yarns in a single weft column moving in the plane of the weave.
[0038] Other known types of three-dimensional weaving may be used, such as those described in document WO 2006 / 136755.
[0039] The fiber blank can be woven from carbon fiber or ceramic yarns such as silicon carbide.
[0040] As the fiber blank, the thickness and width of which vary, is woven, a certain number of warp threads are not woven, which makes it possible to define the desired, continuously variable contour and thickness of the blank 100. An example of scalable 3D weaving, in particular making it possible to vary the thickness of the blank between a first edge intended to form the leading edge and a second edge of lesser thickness and intended to form the trailing edge, is described in document EP 1 526 285.
[0041] During weaving, a delinking 103 (figure 2) is produced inside the fiber blank between two successive layers of warp threads and on a delinking zone 104 (figure 4). The delinking zone 104 makes it possible to provide an internal housing 104a allowing the introduction of an insert, here a spar, inside the fiber blank 100 for the purpose of forming the preform of the aerodynamic profile structure. A 3D weaving mode with interlock weave of the blank 100 is shown schematically in figures 3A and 3B. Figure 3A is an enlarged partial view of two successive warp section planes in a portion of the blank 100 not having a delinking, that is to say in a zone of the blank located outside the delinking zone 104, while Figure 3B shows two successive warp section planes in the portion of the blank 100 having a delinking 103 forming the delinking zone 104.
[0042] In this example, the blank 100 comprises 6 layers of warp yarns 101 extending in the X direction. In Figure 3A, the 6 layers of warp yarns are linked by weft yarns Ti to T5. In Figure 3B, 3 layers of warp yarns 101 forming the set of yarn layers 105 are linked together by two weft yarns T 1 ; T2, as well as the 3 layers of warp threads forming the set of layers of threads 106 are linked by two weft threads T4 and T5. In other words, the fact that the weft threads Ti, T2 do not extend into the layers of threads 106 and that the weft threads T4, T5 do not extend into the layers of threads 105 ensures the unlinking 103 which separates the sets of layers of warp threads 105, 106 from each other.
[0043] At the end of weaving (figure 2), the warp and weft threads are cut, for example using a pressurized water jet, at the limit of the woven mass to extract the dry blank 100 shown in figure 4 as it results from the 3D weaving and before any shaping. The uncoupling zone 104 formed during weaving makes it possible to form two portions 110 and 111 woven independently of each other delimiting an internal housing 104a inside the blank 100. The two portions 110 and 111 are intended to form the skins 21 and 22 of the aerodynamic structure 20. The internal housing 104a is open on the lower edge 100c and on the rear edge 100b of the blank 100.The front edge 100a of the fiber blank 100, which connects the two portions 110 and 111 and which is intended to form the leading edge 20a of the aerodynamic profile structure 20 of the blade 10 while the rear edge 100b of the blank 100 corresponds to the part intended to form the trailing edge 20b of the aerodynamic profile structure (figure 1).
[0044] According to the invention, the manufacture of the blade comprises the use of an insert 40 corresponding here to a spar (figure 4). The insert 40 comprises a first portion 41 and a second portion 42. The first portion 41 which corresponds to the first part 31 of the spar 30 comprises a swollen part 411 and a part of decreasing thickness 412 intended to form respectively the root 33 and Péchasse 34 of the blade 10 (figure 1). The part of decreasing thickness 412 is extended by the second portion 42 which corresponds to the second part 32 of the spar 30.
[0045] In the example described here, the insert 40 is made of metallic material, for example titanium.
[0046] An adhesive film 50 is deposited over the entire surface of the second portion 42 of the insert which corresponds to the part of the insert which is introduced into the internal housing 104a of the dry fibrous blank 100. Thus, an adhesive film is interposed between the insert and the wall of the internal housing 104a after the insertion of the insert into the internal housing of the fibrous blank.
[0047] The adhesive film comprises a layer of thermosetting epoxy resin which may, for example, correspond to epoxy resin EA914 manufactured by Hysol®, to adhesive film AF191 manufactured by 3M®, to adhesive film FM300 manufactured by Cytec®, or to epoxy resin EA9396 manufactured by Hysol®.
[0048] In Figure 4, the shaping of the dry fiber blank 100 is carried out by introducing into the internal housing 104a the second portion 42 of the insert 40 covered with the adhesive film 50. A blade preform 200 is thus obtained comprising, in a longitudinal direction D L an aerodynamic profile preform portion 211 consisting of the dry fibrous blank 100 in the internal housing 104 of which the second portion 42 of the insert 40 has been inserted. The adhesive film 50 is then interposed between the second portion 42 and the dry fibrous blank 100. The aerodynamic profile preform portion 211 extends in a transverse direction D T between a leading edge portion 211 a and a trailing edge portion 211 b.
[0049] As illustrated in Figure 5, the blade preform 200 is placed in an injection tool 300 which comprises a first shell 310 comprising in its center a first imprint 311 corresponding in part to the shape and dimensions of the blade to be produced and a second shell 320 comprising in its center a second imprint 321 corresponding in part to the shape and dimensions of the blade to be produced.
[0050] Once the tool 300 is closed as illustrated in FIG. 6, the first and second impressions 311 and 321 respectively of the first and second shells 310 and 320 together define a molding cavity 301 having the shape of the blade to be produced and in which the preform 200 is held.
[0051] According to the invention, a step of pre-consolidation of the adhesive film is then carried out. In the example described here and as illustrated in FIG. 6, the pre-consolidation step comprises the application of a consolidation pressure in the molding cavity 301. For this purpose, a pressurized gas flow 360 is injected into the molding cavity through an injection port 313 present in the first shell 310 of the tool 300. The pressure inside the molding cavity 301 can be regulated by an evacuation port 323 present in the second shell 320.
[0052] Applying pressure in the molding cavity 301 makes it possible to maintain pressure on the adhesive film through the dry fibrous blank and thus prevent the adhesive from creeping into the pores of the blank. The pressure applied in the molding cavity during the pre-consolidation step may be between 1 bar and 3 bar. The gas flow injected into the port 313 to apply pressure in the molding cavity may be air or an inert gas such as nitrogen in order to limit the risk of porosity.
[0053] The application of a consolidation pressure can be combined with a partial polymerization of the adhesive film during the pre-consolidation step. In this case, a heat treatment cycle is further applied to the preform held in the injection tool. The partial polymerization of the adhesive film makes it possible to increase its creep resistance. In the example described here, the injection tool 300 further comprises a lower part 340 and an upper part 350 between which the first and second shells 310 and 320 are placed, the lower part 340 and the upper part 350 being equipped with heating means (not shown in FIG. 6).
[0054] The duration and temperature stage of the applied thermal cycle determines the level of polymerization of the adhesive. Figure 8 shows an example of operating parameters used in a pre-consolidation step of the adhesive film (“Cycle insert in Figure 8”) combining pressure application and a partial polymerization thermal cycle. In this example, the adhesive is an AF191 adhesive film manufactured by 3M® and the pre-consolidation step is carried out over a period of approximately one hour during which the pressure in the molding cavity is increased to a value between 1 bar and 3 bar while the preform is exposed to a temperature of 110°C after a temperature increase. This makes it possible to obtain a polymerization rate (a1) of the adhesive film of 25%.
[0055] In the case of applying a thermal cycle during the pre-consolidation step, the adhesive film is partially polymerized at a rate preferably between 20% and 50%. This optimizes the bonding of the insert by carrying out the other part of the polymerization of the adhesive film during the injection and final curing of the part.
[0056] The fibrous part of the preform, here the shaped fibrous blank, is then densified, as illustrated in Figure 7. The densification of the fibrous part of the preform consists of filling its porosity with the material constituting the matrix. This densification is carried out in a manner known per se using the liquid process (LC). The liquid process consists of impregnating the preform with a liquid composition containing a precursor of the matrix material. The precursor is usually in the form of a polymer, such as a high-performance epoxy resin, possibly diluted in a solvent.
[0057] The transformation of the precursor into a matrix, namely its polymerization, is carried out by heat treatment, generally by heating the injection tool, after elimination of any solvent and crosslinking of the polymer, the preform always being maintained in the molding cavity having a shape corresponding to that of the part to be produced.
[0058] In the case of carbon or ceramic matrix formation, the heat treatment consists of 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, particularly SiC, can be polycarbosilane (PCS) or polytitanocarbosilane (PTCS) or polysilazane (PSZ) resins, while liquid carbon precursors can be resins with a relatively high coke content, such as phenolic resins. Several consecutive cycles, from impregnation to heat treatment, can be carried out to achieve the desired degree of densification.
[0059] According to one aspect of the invention, in the case in particular of the formation of an organic matrix, the densification of the fibrous preform can be carried out by the well-known transfer molding process known as RTM ("Resin Transfer Molding"). According to the RTM process, the fibrous 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 which includes the fibrous preform. A pressure gradient is generally established in this internal space between the place where the resin is injected and the orifices for discharging the latter in order to control and optimize the impregnation of the preform by the resin.
[0060] As illustrated in Figure 7 and in accordance with the RTM method, a resin 380, for example a thermosetting resin, is injected via the injection port 313 of the first shell 310 into the molding cavity 301 occupied by the preform 200. The port 323 of the second shell 320 is connected to a discharge conduit maintained under pressure (not shown in Figure 7). This configuration allows the establishment of a pressure gradient between the lower part of the preform 200 where the resin is injected and the upper part of the preform located near the port 323. In this way, the resin 360 injected substantially at the level of the lower part of the preform will gradually impregnate the entire fibrous part of the preform by circulating in it up to the discharge port 323 through which the surplus is discharged.Of course, the first and second shells 310 and 320 of the tooling 300 may respectively comprise several injection ports and several evacuation ports.
[0061] The resin used can be, for example, an epoxy resin with a temperature class of 180 °C (maximum temperature supported without loss of characteristics). Resins suitable for RTM processes are well known. They preferably have a low viscosity to facilitate their injection into the fibers. The choice of temperature class and / or the chemical nature of the resin is determined according to the thermomechanical stresses to which the part must be subjected. Once the resin has been injected throughout the reinforcement, it is polymerized by heat treatment in accordance with the RTM process.
[0062] After injection and polymerization, the blade is demolded. Finally, the blade can be trimmed to remove excess resin and the chamfers are machined. No further machining is necessary since, since the part is molded, it meets the required dimensions. This produces blade 10 in Figure 1.
[0063] The densification processes described above make it possible to produce, from the fiber preform of the invention, mainly propeller blades or vanes made of organic matrix composite material (OMC), carbon matrix (C / C) and ceramic matrix (CMC).
[0064] According to an optional feature of the method of the invention, the adhesive film may further comprise a fibrous interface texture. The fibrous interface texture is a thin layer whose thickness makes it possible to define or calibrate the thickness of the interface (adhesive joint) between the insert and the part of the fibrous blank with which the adhesive film is in contact. The thickness of the fibrous interface texture is preferably less than 1 mm. The fibrous interface layer may have various types of texture such as, in particular, a marquisette, a two-dimensional woven fabric, a knit, a felt, a veil, a braid or a mat.
Claims
Claims
1. Method of manufacturing a turbomachine propeller blade or vane (10), the method comprising: - the production of a fibrous blank (100) of an aerodynamically profiled structure by three-dimensional weaving of threads, said blank comprising an internal housing (104a), - inserting at least one insert (40) into the internal housing (104a) with the interposition of an adhesive film (50) between the insert and the internal housing of the fiber blank so as to obtain a fiber preform (200), - holding the fiber preform (200) in a molding cavity (301) of an injection tool (300) having the shape of the blade or propeller blade to be manufactured, - injecting a resin (380) into the molding cavity (301) containing the fiber preform (200) and transforming the resin into a matrix by heat treatment, characterized in that the method further comprises, after maintaining the fiber preform (200) in the molding cavity (301) and before injecting the resin (380) into the fiber preform, a step of pre-consolidating the adhesive film comprising at least the application of a consolidation pressure in the molding cavity (301).
2. The method of claim 1, wherein the application of the consolidation pressure in the molding cavity (301) is carried out by injecting an inert gas under pressure into the molding cavity.
3. The method of claim 1 or 2, wherein the adhesive film (50) comprises a layer of thermosetting epoxy resin.
4. The method of any one of claims 1 to 3, wherein the step of pre-consolidating the adhesive film (50) further comprises partially polymerizing the adhesive film by applying a heat treatment.
5. The method of claim 4, wherein the adhesive film is partially polymerized at a rate of between 20% and 50%.
6. A method according to any one of claims 1 to 5, wherein the adhesive film further comprises an interface fibrous texture.
7. Method according to any one of claims 1 to 5, wherein the material of said at least one insert (40) is chosen from one of the following materials: metallic material, composite material or polymer comprising a waterproof surface coating.