Method for producing a blade made from composite material

Abstract

The invention relates to a method for producing a blade made from composite material, comprising the following steps: (a) successively stacking several layers of fibres to form a fibrous blank (200) having first and second portions connected to one another in a continuous manner; (b) shaping the fibrous blank (200) by folding along a line (P) so as to form, on either side of the line (P), lower and upper skins of a fibrous preform (220) of a blade airfoil, the leading edge, or alternatively the trailing edge, of the airfoil being located at, and along, this line (P); and (d) densifying the fibrous preform (220) with a resin to form the blade made from composite material.

Description

[0001] DESCRIPTION

[0002] TITLE: METHOD FOR MANUFACTURING A BLADE MADE OF COMPOSITE MATERIAL

[0003] Technical field of the invention

[0004] The present invention relates to the general field of the manufacture of blades for turbomachines, in particular aircraft.

[0005] Technical background

[0006] The state of the art includes in particular documents GB-A-1302857, EP-A1-3542999 and US-A1-4626172.

[0007] Turbomachines, in particular double-flow turbomachines, are known, comprising a fan arranged upstream of a gas generator according to the circulation of the gases in the turbomachine. The gas generator is housed in an internal annular casing while the fan is housed in an external annular casing generally secured to a nacelle. The fan generates a primary flow or hot flow circulating in a primary vein passing through the gas generator, and a secondary flow or cold flow circulating in a secondary vein around the gas generator.

[0008] The blower comprises blower blades each with a free end facing the outer casing so as to compress an incident air flow at least in the secondary vein and, preferably, also in the primary vein.

[0009] A turbomachine blade typically comprises a blade that has an aerodynamic shape. The blade comprises a pressure face and an extrados face connected to each other by a leading edge and a trailing edge of the blade. The blades can be metallic or made of a composite material, such as an organic matrix composite material, in particular to reduce their mass.

[0010] A commonly used composite material comprises a fiber preform embedded in a polymer resin. The fiber preform may be produced by three-dimensional (3D) weaving or may be obtained by stacking (or otherwise known as draping) and superimposing several layers / plies of fibers (for example in the form of strips or ribbons). The resin may be injected into the fiber preform or the fiber preform may be pre-impregnated with the resin (also referred to as "pre-impregnated" or "prepreg" in English).

[0011] The stacking of the fiber layers can be carried out manually or automatically by a suitable machine, in particular using the AFP technique (acronym for "Automated Fiber Laying"), the ATL technique (acronym for "Automated Tape Laying") or the P&P technique (acronym for "Pick&Place" for a picking and positioning system).

[0012] One method of manufacturing composite blades is to make a lower surface skin from a first fiber preform to form the lower surface of the blade, then to make a higher surface skin from a second fiber preform to form the upper surface of the blade. The first and second fiber preforms are obtained by successively stacking several layers of fibers. Then, the opposite ends of the lower and upper skins are fixed together to form the leading edge and the trailing edge of the blade after densification with a polymer resin in order to obtain the final blade. Another method of manufacturing composite blades is to stack the fiber plies to make a fiber preform forming a skin intended to form the lower surface to the upper surface of the blade. Then, the opposite ends of the skin are fixed together.For example, the fixing of the skin ends can be carried out by gluing or directly by polymerization of the resin during densification.

[0013] Such an attachment of the intrados and extrados skins has the disadvantage of being a weak connection which can easily weaken the leading edge and the trailing edge, particularly in the event of shocks or impact from a foreign body during operation. This can often dissuade designers from making blades from composite material by stacking layers of fibers.

[0014] To overcome this drawback, it may be necessary to create a stack of layers with continuous fibers to form a strong bond between the intrados and the extrados of the blade.

[0015] To achieve this, the stack of fiber layers can be made in the shape of a spar on a reinforcing support (such as a mandrel). However, the aerodynamic shape of the blade (i.e. a twisted shape) can make it complex, or even impossible, to remove the reinforcing support placed inside the spar. The use of a reinforcing support that can be fissionable or removable is not reliable, particularly during a shaping step (also referred to as "forming") of the spar. Indeed, the fissionable or removable support cannot withstand compaction pressure exerted locally on the reinforcing support by a deposition head of the AFP technique. In addition, certain areas of the blade may be thin (for example with direct contact between the intrados and extrados skins to form the trailing edge in particular) to accommodate the reinforcing support.However, the absence of reinforcement support (i.e. in a vacuum) can prevent the blade from being produced by stacking plies, particularly using an automated machine such as the AFP technique.

[0016] There is therefore a need to optimize the manufacture of blades in composite material by stacking layers of fibers, while ensuring good mechanical resistance of the blades to impacts during operation.

[0017] Summary of the invention

[0018] The present invention provides a simple, effective and economical solution to this problem.

[0019] The invention proposes a method for manufacturing a blade made of composite material for an aircraft turbomachine, the blade comprising a blade having a lower surface and an upper surface connected to each other by a leading edge and a trailing edge, the method comprising the following steps: (a) successively stacking several layers of fibers to form a fiber blank,

[0020] (b) shaping said fibrous blank to obtain a fibrous preform of the blade, said fibrous preform comprising an intrados skin and an extrados skin joined together and intended to form, respectively, the intrados and the extrados of the blade, and

[0021] (d) densifying said fibrous preform with a resin to form the composite material blade.

[0022] According to the invention, the fiber blank comprises first and second portions continuously connected to each other in step (a). In addition, step (b) comprises folding the fiber blank along a line extending between said first and second portions so as to form, on either side of the folding line, said intrados and extrados skins.

[0023] The leading edge, or alternatively the trailing edge, of the blade is located at and along this fold line, and the edges of the intrados and extrados skins, opposite this fold line, are joined to form the leading edge, or alternatively the trailing edge, of the blade.

[0024] Thus, this solution makes it possible to achieve the aforementioned objective. In general, the method according to the invention makes it possible to simplify and optimize the manufacture of a blade made of composite material using the technique of stacking layers of fibers.

[0025] In particular, step (a) of the method makes it possible to stack the fiber layers to form a fiber blank with continuous fibers. Step (b) of folding this fiber blank along a fold line makes it possible to join the intrados and extrados skins of the fiber preform and form the leading edge, or alternatively the trailing edge, of the blade at this fold line. The fold line thus makes it possible to form a robust connection zone between the intrados and extrados skins, since this connection zone is formed by continuous fibers.

[0026] Thus, the composite material blade produced by such a process has a strong bond, in particular at the leading edge and / or the trailing edge, so as to reinforce the mechanical strength of the blade, particularly in the event of shocks or impact from a foreign body during operation.

[0027] According to the invention, the fiber blank and / or the fiber preform are formed on a surface of a support which is planar, U-shaped or V-shaped, wherein said surface of the support further comprises a U-shaped or V-shaped projecting portion and configured to define said fold line. The method comprises, in step (a), a step (i) of preforming at least a portion of the fiber blank formed on said U-shaped or V-shaped projecting portion of the support.

[0028] This preforming step (i) makes it possible to directly preform a so-called bonding zone on the fiber blank at the fold line, in particular before folding the fiber blank in step (b). In this way, folding the fiber blank is made easier and the dimensions of the bonding zone between the intrados and extrados skins are better controlled. Consequently, the mechanical strength of the composite material blade is reinforced (in particular at the leading edge and / or the trailing edge).

[0029] In the present application, a turbomachine blade may be shrouded, as is the case with a fan for example, or may be unshrouded, as is the case with a propeller of an open-rotor type architecture for example.

[0030] The manufacturing method according to the invention may comprise one or more of the following characteristics, taken in isolation from one another or in combination with one another: - in step (a) or (b), the fiber blank has a generally flat and / or curved U- or V-shaped shape;

[0031] - step (a) is carried out manually or by machine;

[0032] - step (d) comprises impregnation of the fiber preform with the resin and polymerization of the resin by heat treatment;

[0033] - the resin is injected into the fiber preform before step (d), or the fiber blank is previously impregnated with the resin;

[0034] - the resin is thermosetting, and is for example an epoxy resin;

[0035] - the resin is thermoplastic, for example a polyether-ether-ketone resin, polyaryletherketone or polyether-imide;

[0036] - it comprises a step (c) of adding at least one reinforcing insert in an internal space delimited by the intrados and extrados skins of the fiber preform, for example the reinforcing insert is made of foam, cellular material or composite material.

[0037] -- step (b) is a step of forming the fiber blank;

[0038] - in step (b), the folding of the fiber blank is carried out by compaction, for example with a pressure of between 300 and 800 Pascal;

[0039] - in step (b), the folding of the fiber blank is carried out by compaction with a depression, for example between -300 and -900 mBar (namely - 30000 and -90000 Pascal); - step (b) is carried out at a predetermined temperature which can be variable depending on the resin chosen, for example the predetermined temperature is between 30°C and 100°C, in particular in the case of layers of fibers pre-impregnated with a thermosetting resin;

[0040] - the method comprises a step (i) of preforming at least a portion of the fibrous blank formed on said projecting portion;

[0041] - this step (i) is carried out during step (a);

[0042] - the fiber layers each comprise glass fibers, carbon fibers, aramid fibers, polyamide fibers, ceramic fibers, metal fibers, oxide fibers, or a mixture of at least two of these fibers; - the reinforcing insert comprises a sealing envelope coating the cellular material;

[0043] -- the cellular material of the reinforcement insert is chosen from a polymer foam, an aluminum foam, a metal honeycomb and / or an aramid polymer;

[0044] - the reinforcement insert can be produced by additive manufacturing;

[0045] -- the reinforcement insert can be made in a thermoplastic structure.

[0046] The invention also relates to a composite material blade for an aircraft turbomachine, produced by a manufacturing method as described above.

[0047] Brief description of the figures

[0048] The invention will be better understood and other details, characteristics and advantages of the invention will appear more clearly on reading the following description given by way of non-limiting example and with reference to the appended drawings in which:

[0049] - figure 1 is a half schematic view in axial section of an aircraft turbomachine:

[0050] - figure 2 is a schematic perspective view of a blade of the turbomachine of figure 1;

[0051] - figure 3 is a block diagram of a manufacturing method according to the invention, of the blade of figure 2 made of composite material;

[0052] - figure 4a is a schematic sectional view of a fiber blank obtained by the manufacturing method of the invention;

[0053] - figure 4b is a schematic sectional view of the folded fiber blank of figure 4a;

[0054] - Figure 5 is a schematic sectional view of a fiber preform obtained by the manufacturing method of the invention;

[0055] - figure 6 is a schematic view of part of the steps of the manufacturing method of figure 3 according to a first embodiment, in which the method uses a support of generally planar shape;

[0056] - figure 7a is a schematic view of the support of generally planar shape of figure 6, comprising a projecting portion according to a first variant;

[0057] - figure 7b is a schematic view of the support of generally planar shape of figure 6, comprising a projecting portion according to a second variant;

[0058] - Figure 8 is a schematic view of part of the steps of the manufacturing method of Figure 3 according to a second embodiment, in which the method uses a support of generally curved shape;

[0059] - figure 9a is a schematic view of the support of generally curved shape of figure 8, comprising a projecting portion according to a first variant;

[0060] - figure 9b is a schematic view of the support of generally curved shape of figure 8, comprising a projecting portion according to a second variant;

[0061] - figure 10 is a schematic view of part of the steps of the manufacturing method of figure 3 according to another embodiment;

[0062] - figure 11 a is a schematic axial sectional view of a fiber preform comprising a reinforcing insert according to a first variant;

[0063] - figure 11 b is a schematic axial sectional view of a fiber preform comprising a reinforcing insert according to a second variant.

[0064] Elements having the same functions in different implementations have the same references in the figures.

[0065] Detailed description of the invention

[0066] By convention, in the following description, the terms "longitudinal" and "axial" describe the orientation of structural elements extending in the direction of a longitudinal axis. The terms "radial" or "vertical" describe an orientation of structural elements extending in a direction perpendicular to the longitudinal axis. The terms "inner" and "outer", and "internal" and "external" are used in reference to a positioning relative to the longitudinal axis. Thus, a structural element extending along the longitudinal axis has an inner face facing the longitudinal axis and an outer surface, opposite its inner surface.

[0067] A turbomachine 1 of the shrouded type, in particular for an aircraft, is for example shown in Figure 1. The turbomachine 1 may be a turbojet or turboprop.

[0068] The turbomachine 1 extends around a longitudinal axis X. It comprises from upstream to downstream in the direction of flow of the gases F along the longitudinal axis X, a fan 1 a, at least one compressor such as a low pressure compressor 1 b and a high pressure compressor 1 c, a combustion chamber 1 d, at least one turbine 1 e such as a high pressure turbine and a low pressure turbine, and a nozzle (not shown).

[0069] The turbomachine 1 further comprises a rectifier 1f. The rectifier 1f makes it possible to straighten the flow at the outlet of a rotor located upstream in order to provide maximum thrust at the outlet of the turbomachine 1. In the particular example of figure 1, the rectifier 1f is located downstream of the fan 1a and makes it possible to straighten a secondary flow F2.

[0070] The blower 1a allows the suction of an air flow dividing into a primary flow F1 and a secondary flow F2. The primary flow F1 passes through a primary vein of the turbomachine 1 while the secondary flow F2 is directed towards a secondary vein surrounding the primary vein.

[0071] The primary flow F1 is compressed within the low-pressure compressor 1b and then the high-pressure compressor 1c. The compressed air is then mixed with fuel and burned within the combustion chamber 1d. The gases formed by the combustion pass through the high-pressure turbine and the low-pressure turbine. The gases finally escape through the nozzle, the cross-section of which allows the acceleration of these gases to generate propulsion. The secondary flow F2 passes through the rectifier 1f, which accelerates the circulation speed of the secondary flow F2 to generate propulsion.

[0072] The fan 1a, the low pressure compressor 1b, the high pressure compressor 1c, the high pressure and / or low pressure turbine 1e, and the rectifier 1f comprise blades 2. The blades 2 can be mobile (for example the blade of figure 2) in rotation around the longitudinal axis X, or fixed (for example the blade 2 called OGV for “Outlet Guide Vane” of the rectifier 1f of figure 1) relative to the axis X.

[0073] The invention relates to the manufacture of a blade made of composite material for a turbomachine, in particular an aircraft. In the following description, the blade of the invention will be described in the context of its application to the fan 1a of the turbomachine 1 of FIG. 1.

[0074] The invention is however not limited to a fan blade of a shrouded turbomachine, and can also be applied to other types of blades made of composite material (such as fixed or moving blades of the low pressure 1b and high pressure 1c compressors, of the high pressure and low pressure turbines of the turbomachine 1). The invention can be applied to a propeller of an unshrouded turbomachine (for example an open-rotor type architecture).

[0075] With reference to Figure 2, each blade 2 extends, on the one hand, along a longitudinal axis A (arranged horizontally in Figure 2), and on the other hand, along an elongation axis B (arranged vertically in Figure 2). This axis A is substantially perpendicular to the axis B. The axis A is substantially parallel to the axis X of the turbomachine 1.

[0076] The blade 2 comprises a blade 20. The blade 20 comprises a lower surface 21 and an upper surface 22 connected to each other by a leading edge 23 and a trailing edge 24. The blade 20 may have an aerodynamic profile to form the aerodynamic part of the blade 2. For this, the blade 20 may have a curved profile of variable thickness between its leading edge 23 and its trailing edge 24. The blade 20 may comprise a first longitudinal end connected to a root 26 of the blade 2 and a second longitudinal end opposite the first longitudinal end. The second longitudinal end is free and configured to form a blade tip 25 (or a head).

[0077] The blade 2 may also comprise a reinforcement or shield 3 for protecting the leading edge 23, in the form of a metal foil. In the example, the shield 3 extends in height (relative to the axis A) and over a portion in length (relative to the axis B) of the intrados face 21 and the extrados face 22 from the leading edge 23 of the blade 20.

[0078] As previously described in the technical background of the invention, a composite material blade can be made by stacking layers of fibers.

[0079] A manufacturing method according to the invention of the blade 2 will now be described with reference to figures 3 and 11 b.

[0080] Figure 3 represents a block diagram of an exemplary embodiment of the method of the invention.

[0081] Generally, the manufacturing process of the blade 2 may comprise the following steps:

[0082] (a) successively stacking several layers of fibers 202 to form a fiber blank 200,

[0083] (b) shaping this fibrous blank 200 to obtain a fibrous preform 220 of the blade 20, and

[0084] (d) densifying this fibrous preform 220 with a resin to form the blade 2 made of composite material.

[0085] One of the particularities of the invention is that the fiber blank 200 of step (a) comprises a first portion 204 and a second portion 206 connected together continuously. In other words, the first 204 and second 206 portions are formed integrally with continuous fibers. This makes it possible to reinforce the mechanical strength of the blade, in particular at the leading edge 23 and / or the trailing edge 24 in the event of shocks or impact from a foreign body during operation.

[0086] For example, the fiber layers 202 include glass fibers, carbon fibers, aramid fibers, polyamide fibers, ceramic fibers, metal fibers, oxide fibers, or a mixture of at least two of these fibers.

[0087] The fiber layers 202 may be pre-impregnated with resin or be in a raw state (or other so-called dry fibers). The term “fibers in the raw state” or “dry fibers” means the fiber layers 202 comprising fibers not previously impregnated with resin.

[0088] The fiber layers 202 may comprise a binder.

[0089] In the example of Figure 4a, the fiber blank 200 has a generally planar shape. Alternatively, the fiber blank 200 may have a generally curved shape, in particular U-shaped or V-shaped (Figure 8). The curved shape of the fiber blank 200 makes it possible in particular to facilitate the formation of a folding line P in step (b) which is described below.

[0090] In particular, step (b) comprises folding the fiber blank 200 along the so-called folding line P (figures 4b). This line P can be substantially parallel to the axis A. The folding line P extends between the first 204 and second 206 portions so as to form, on either side of this folding line P, intrados 222 and extrados 224 skins of the fiber preform 220 (figure 5).

[0091] As illustrated in the examples of Figures 4b and 5, the first 204 and second 206 portions are in particular folded together to join the intrados 222 and extrados 224 skins together. The first portion 204 may be configured to form the intrados skin 222 and the second portion 206 may be configured to form the extrados skin 224 of the fiber preform 220.

[0092] With reference to figure 5, the fiber preform 220 of step (b) therefore comprises the intrados skin 222 intended to form the intrados 21, and the extrados skin 224 intended to form the extrados 22 of the blade 20. The intrados 222 and extrados 224 skins are joined together, in particular along the folding line P.

[0093] The leading edge 23, or the trailing edge 24, is located at and along this fold line P.

[0094] The intrados skin 222 may comprise a first edge 226 opposite the folding line P (in particular radially relative to the line P). The extrados skin 224 may comprise a second edge 228 opposite the folding line P.

[0095] In the example of Figure 5 and in a non-limiting manner, the first 226 and second 228 edges are joined to form the leading edge 23 located on the folding line P.

[0096] Advantageously, step (a) of the method can be carried out manually or by a machine 4. The machine 4 can be automated or mechanized. For example, step (a) can be carried out by an automated machine 4, in particular according to the AFP, ATL or P&P technique.

[0097] Step (b) of shaping (or otherwise known as forming) the fiber blank 200 may be carried out at a predetermined temperature, called the forming temperature. This forming temperature may be low, between 30°C and 100°C, for example, in the case of a layer of fibers 202 pre-impregnated with a thermosetting resin. The forming temperature may vary depending on the polymerization resin used. A heating system (for example, an oven) may be used in step (b) to shape the fiber blank by heating.

[0098] The folding of step (b) can be carried out by compaction at a predetermined pressure and / or at a predetermined depression. For example, the compaction of the fiber blank 200 is carried out at a depression which can be between -300 and -900 mBar, for example in the case of a layer of fibers 202 pre-impregnated with resin.

[0099] The compaction pressure or vacuum may vary depending on the resin material. Pressure may be applied in addition to or alternatively to the vacuum. In this case, the compaction pressure may be between 1 and 10 Bar, for example in the case of a layer of fibers 202 pre-impregnated with resin.

[0100] Step (b) can be carried out in an oven, an autoclave, a press or any other tool suitable for folding the fiber blank 200.

[0101] At the end of step (b) of the method, the intrados 222 and extrados 224 skins of the formed fiber preform 220 are joined together by the first and second edges 226, 228 forming the leading edge 23 (in the example of FIG. 5) or the trailing edge 24.

[0102] Figures 6, 8 and 10 illustrate, respectively, a first mode, a second mode and a third embodiment of the blade 2.

[0103] In the first embodiment of the method of the invention illustrated in Figure 6, step (a) is carried out by the machine 4, in particular of the AFP type. For this, the machine 4 comprises a head 40, called a draping or stacking head, and a first support 42 called a stacking head. The head 40 makes it possible to successively deposit several layers of fibers superimposed on each other, in particular on a first surface 44 of the first support 42. In the example of Figure 6, the first surface 44 is flat. Thus, the fiber blank 200 obtained at the end of this step (a) has a flat shape.

[0104] Alternatively, the first surface 44 of the first support 42 is curved, in particular in a U or V shape (figure 8) to define the fiber blank 200 with a curved U or V shape (figure 8).

[0105] Advantageously, the first surface 44 may comprise a first projecting portion 46. This first projecting portion 46 makes it possible to define the folding line P. Thus, the first projecting portion 46 may be configured to form the leading edge 23 and / or the trailing edge 21 of the blade 20. The first projecting portion 46 may have a general U-shape (FIG. 7a) or V-shape (FIG. 7b). In step (b), the fiber blank 200 may be mounted on a second surface 50 of a second support 5 called a forming support. In the example of FIG. 6, the second surface 50 is flat. Alternatively, the second surface 50 of the second support 5 is curved, in particular in a U-shape or a V-shape (FIG. 8).

[0106] Advantageously, the second surface 50 may comprise a second projecting portion 52. This second projecting portion 52 makes it possible to define the folding line P. Thus, the second projecting portion 52 may be configured to form the leading edge 23 and / or the trailing edge 21 of the blade 20. The second projecting portion 52 may have a general U-shape (FIG. 7a) or V-shape (FIG. 7b).

[0107] A single support 42, 5 can be used to carry out both steps (a) and (b), or on the contrary two different supports 42, 5 can be used to carry out steps (a) and (b) of the method of the invention.

[0108] At the end of step (b) of the example of FIG. 6, the fiber preform 220 comprises intrados 222 and extrados 224 skins joined together.

[0109] The second embodiment illustrated in Figure 8 is distinguished from the method of the first embodiment of Figure 6 by the first 42 and second 5 supports.

[0110] In the second embodiment, the first 44 and second 50 surfaces of the supports 42, 5 have a generally curved V-shaped shape. Thus, the fiber blank 200 obtained in step (a) has a curved V-shaped shape.

[0111] The machine 4 may further comprise a holding member 48 (for example a cylindrical plate). This holding member 48 makes it possible in particular to support the curved V-shape of the first surface 44 of the first support 42.

[0112] As described with reference to Figures 7a and 7b, the first 44 surface of the first support 42 of the second embodiment may comprise the first projecting portion 46 (Figures 9a and 9b). Similarly, the second 50 surface of the second support 5 of the second embodiment may comprise the second projecting portion 52 (Figures 9b and 9b). The first 46 and second 52 projecting portions make it possible to define the folding line P and also in particular the leading edge 23, or the trailing edge 21, of the blade 20. The first 46 and second 52 projecting portions of the second embodiment may each have a general U-shape (Figure 9a) or V-shape (Figure 9b).

[0113] Alternatively (not shown in the figures), the first 44 and second 50 surfaces, respectively, of the first 42 and second 5 supports, are each U-shaped to define the fiber blank 200 with a U-shaped curved shape. These first 44 and second 50 U-shaped curved surfaces may include first 46 and second 52 projecting portions, as described with reference to the first and second embodiments of the invention.

[0114] The method of the invention may comprise a step (i) of preforming at least a portion of the fiber blank 200 formed on the first 46 or second portion 52 projecting from the support 42, 5, for example in the shape of a U or V. This step (i) may be carried out during or after step (a). This makes it possible to directly preform the connection zone (at the level of the folding line P) on the fiber blank 200, before the step (b) of folding the fiber blank 200 to form the folded intrados 222 and extrados 224 skins. Thus, the dimensions (shape, size, thickness, etc.) of the connection zone of the intrados 222 and extrados 224 skins, at the level of the folding line P, are better controlled.

[0115] By way of example, Figure 10 illustrates the preforming step (i) after the step (a) of stacking the layers of fibers 202 and before folding the fiber blank 200 in step (b). The fiber blank 200 thus comprises a middle portion 205 between the first 204 and second 206 portions. This middle portion 205 is located at the level of the folding line P, and configured to form the leading edge 23, or the trailing edge 24, of the blade 20. The U or V shape of the projecting portion 46, 52 of the support 42, 5 makes it possible in particular to compact the middle portion 205 to form a so-called intermediate fiber preform 225. The first 204 and second 206 portions of the fiber blank 200 extend on either side of this intermediate preform 225. Then, in step (b), the first 204 and second 206 portions are folded together to form the fiber preform 220.The densification step (d) of the process may comprise the polymerization of the resin by heat treatment (or in other words the hardening of the resin into a polymer matrix). For this, the fiber preform 220 may be previously impregnated with the resin, in particular in step (a) and / or in step (i), during the production of the fiber blank 200, 201, 203. For example, the head 40 of the machine 4 deposits strands in the form of a mixture of fibers and resin in layers superimposed on each other and forms the pre-impregnated fiber blank. In this case, step (d) can be carried out in an autoclave, using the resin injection molding technique which is similar to the resin of the pre-impregnated fiber layers “SQRTM” (Same Qualified Resin Transfer Molding) or any other technique allowing the polymerization of a fiber preform with a controlled geometry.

[0116] Alternatively, the densification step (d) of the method may comprise an injection of resin into the fiber preform 220, and a polymerization of the resin by heat treatment. For this, the fiber preform 220 comprises layers of dry fibers 202. For example, the composite material blade may be produced by the liquid resin injection molding technique “RTM” (acronym for “Resin Transfer Molding”). For this, the fiber preform 220 obtained in step (b) may be placed in a mold to be densified by a polymer matrix which consists of impregnating the fiber preform 220 with an injected resin and polymerizing the latter to obtain the final blade. The resin may be injected into the fiber preform 220 before or at step (d).

[0117] The resin can be thermosetting, such as epoxy resin.

[0118] The resin may be thermoplastic, such as a polyether-ether-ketone resin, polyaryletherketone or polyether-imide. The method of the invention may further comprise a step (c) of adding at least one reinforcing insert 232 in an internal space 230 delimited by the intrados 222 and extrados 224 skins of the fiber preform 220. This insert makes it possible in particular to hold the intrados and extrados skins in place during step (d) of densifying the fiber preform.

[0119] The reinforcing insert 232 may be housed in the entire surface of the internal space 230 (Figure 11 a). Alternatively, the reinforcing insert 232 may be positioned at a few predefined locations in the internal space 232 (Figure 11 b).

[0120] With reference to figure 11 b, several reinforcing inserts 232 in the form of stiffeners extend radially (relative to the line P or the axis A) between the intrados 222 and extrados 224 skins.

[0121] The reinforcing insert 232 may be made of foam, cellular material or composite material. For example, the cellular material is selected from a polymer foam (for example, polymethacrylic imide of the Rohacell® type), an aluminum foam, a metal honeycomb and / or an aramid polymer (for example, of the Nomex® type).

[0122] The reinforcing insert 230 may comprise a sealing envelope coating the cellular material. This makes it possible to protect the cellular material, in particular during step (d). This sealing envelope may be made of composite material.

[0123] The 230 reinforcement insert can be produced by additive manufacturing.

[0124] The reinforcing insert 230 can be made in a thermoplastic structure which can be injected between the intrados 222 and extrados 224 skins.

Claims

DEMANDS 1. Method for manufacturing a blade made of composite material (2) for an aircraft turbomachine (1), the blade (2) comprising a blade (20) having an intrados (21) and an extrados (22) connected to each other by a leading edge (23) and a trailing edge (24), the method comprising the following steps: (a) successively stack several layers of fibers (202) to form a fibrous blank (200), (b) shaping said fibrous blank (200) to obtain a fibrous preform (220) of the blade (20), said fibrous preform (220) comprising an intrados skin (222) and an extrados skin (224) joined together and intended to form, respectively, the intrados (21) and the extrados (22) of the blade (20), and (d) densify said fibrous preform (220) with a resin to form the blade of composite material (2), characterized in that the fibrous blank (200) comprises first (204) and second (206) portions connected together continuously in step (a), in that step (b) comprises a folding of the fibrous blank (200) along a line (P) extending between said first (204) and second (206) portions so as to form, on either side of the folding line (P), said lower (222) and upper (224) skins, and in that the leading edge (23), or alternatively the trailing edge (24), of the blade is located at and along this folding line (P), and the edges (226, 228) of the lower (222) and upper (224) skins, opposite this folding line (P), being joined to form the leading edge (23), or alternatively the trailing edge (24), of the blade (20);in that the fibrous blank (200) and / or the fibrous preform (220) are formed on a surface (44, 50) of a support (42, 5) which is flat, U-shaped or V-shaped, said surface (44, 50) of the support (42, 5) further includes a projecting portion (46, 52) in the shape of a U or V and configured to define said bend line (P); and in that the process includes, in step (a), a step (i) of preforming at least a portion of the fibrous blank (200) formed on said U- or V-shaped protruding portion (46, 52) of the support (42, 5).

2. Manufacturing process according to claim 1, characterized in that, at step (a) or (b), the fibrous blank (200) has a generally flat and / or U- or V-shaped curve.

3. Manufacturing process according to claim 1 or 2, characterized in that step (a) is carried out manually or by a machine (4).

4. A manufacturing process according to any one of claims 1 to 3, characterized in that step (d) comprises impregnating the fibrous preform (220) with the resin and polymerizing the resin by heat treatment.

5. Manufacturing process according to claim 4, characterized in that the resin is injected into the fibrous preform (220) before step (d), or the fibrous blank (200) is pre-impregnated with the resin.

6. A manufacturing process according to claim 4 or claim 5, characterized in that the resin is thermosetting, and is for example an epoxy resin.

7. A manufacturing process according to claim 4 or claim 5, characterized in that the resin is thermoplastic, and for example a polyether-ether-ketone resin, polyaryletherketone or polyether-imide.

8. A manufacturing method according to any one of claims 1 to 7, characterized in that the method comprises a step (c) of adding at least one reinforcing insert (232) into an internal space (230) delimited by the intrados (222) and extrados (224) skins of the fibrous preform (220), for example the reinforcing insert (232) is made of foam, cellular material or composite material.

9. Manufacturing method according to claim 8, characterized in that said reinforcing insert (232) is made of cellular material, and this reinforcing insert (232) comprises a sealing envelope encasing the cellular material.

10. Manufacturing method according to claim 8 or claim 9, characterized in that the reinforcing insert (232) is produced by additive manufacturing.

11. A manufacturing process according to any one of the preceding claims, characterized in that the fiber layers (202) each comprise glass fibers, carbon fibers, aramid fibers, polyamide fibers, ceramic fibers, metallic fibers, oxide fibers, or a mixture of at least two of these fibers.

12. Manufacturing method according to any one of the preceding claims, characterized in that in step (b), the folding of the fibrous blank (200) is carried out by compaction with a pressure between 300 and 800 Pascals.

13. Manufacturing method according to any one of claims 1 to 11, characterized in that in step (b), the folding of the fibrous blank (200) is carried out by compaction with a depression between -300 and -900 mBar.

14. A manufacturing process according to any one of the preceding claims, characterized in that step (b) is carried out at a predetermined temperature between 30°C and 100°C when the layers of fibers (202) are pre-impregnated with a thermosetting resin.

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