Fan blade or stationary blade with cross-shaped or star-shaped composite root

Abstract

A turboprop engine blade or propeller blade (10) made of a composite material comprising a fibrous reinforcement densified by a matrix, the blade or propeller blade comprising, in a spanwise direction (DL), a root (12) and an aerodynamic profile (11). The fibrous reinforcement comprises a fibrous preform having a three-dimensional weave, a root preform being located in the root (12) and an aerodynamic profile preform being located in the aerodynamic profile, the root preform and the aerodynamic profile preform being connected to each other by the three-dimensional weave. The root (12) comprises a plurality of branches. The root preform portion of the fibrous preform comprises a plurality of branches, each extending in a branch (23, 24, 25, 26) of the root (12).

Description

Technical Field

[0001] The present invention relates to the field of aircraft blades or propeller blades, such as those found on turboprop engines. Background Art

[0002] The blades or winglets for turboprop engines are usually made of metal materials. Although blades or propeller winglets made of metal materials have good mechanical resistance, they have the disadvantage of being relatively large in mass.

[0003] In order to obtain lighter blades or propeller airfoils, it is known to produce propeller airfoils made of composite materials, namely by producing structural components with fiber reinforcements densified by means of a matrix.

[0004] Document US 2013 / 0017093 describes the production of a propeller blade based on a fiber structure having an aerodynamic profile into which is inserted a portion of a strut, one end of which is extended by a bulge forming the root of the propeller blade.

[0005] New engine generations require more compact blade or wing roots. This requirement stems from the need to be able to pivot the blade or wing about its vertical axis in order to adapt its angle of incidence to the flight class (variable pitch blade or wing). This need, combined with the fact that the blade or wing must be incorporated as low as possible on the disk, makes it possible to significantly reduce the volume of the root.

[0006] To this end, the root of the new generation of blades or airfoils has an axisymmetric or substantially axisymmetric shape and reduced dimensions, unlike the roots of the prior art (such as the roots described in document US2013 / 0017093), in which the root extends over the entire length of the lower part of the blade or airfoil.

[0007] Such axisymmetric or quasi-axisymmetric shapes are more difficult to manufacture as composite materials, particularly when three-dimensional (3D) weaving is used to form the fiber reinforcement of the blade or airfoil.

[0008] Furthermore, the mechanical loads to which the new generation roots are subjected impose additional stresses. Specifically, in addition to the mechanical tensile and bending loads normally encountered (caused by centrifugal forces and object impact, respectively), the new generation roots may be incorporated into the rotor disk using a metal shell, thereby generating additional mechanical circumferential compressive loads. Summary of the invention

[0009] It would therefore be desirable to be able to provide a solution for producing aircraft blades or propeller winglets made of composite materials which have a compact root and are able to withstand different mechanical loads.

[0010] To this end, the invention provides a method for manufacturing a turboprop blade or propeller wing made of composite material, the turboprop blade or propeller wing comprising a fiber reinforcement densified by a matrix, the method comprising:

[0011] - producing a fiber blank by three-dimensional (3D) weaving, the fiber blank being made in one piece, the fiber blank having a flat shape extending in a longitudinal direction and in a transverse direction, the longitudinal direction and the transverse direction respectively corresponding to the span direction and the chord direction of the blade or propeller wing to be manufactured, the fiber blank comprising a root and an aerodynamic profile extending from the root of the fiber blank in the longitudinal direction and in the transverse direction between a leading edge portion and a trailing edge portion,

[0012] - shaping said fiber blank so as to obtain a one-piece fiber preform having said aerodynamic profile forming an aerodynamic profile preform part and said root forming a root preform part, and - densifying said preform by means of a matrix so as to obtain a blade or a propeller blade made of composite material having a fiber reinforcement consisting of said fiber preform and densified by means of said matrix and forming a one-piece with an integrated root,

[0013] It is characterized in that the root of the fiber blank includes a plurality of non-interconnected parts extending along a plane parallel to the surface of the fiber blank, each non-interconnected part extends from the edge of the root of the fiber blank along the transverse direction and extends a distance less than half of the width of the root, each non-interconnected part separates two woven parts in the fiber blank, and shaping the fiber blank includes: orienting the woven parts separated by the non-interconnected parts in different directions to form a root preformed part including a plurality of branches.

[0014] The method of the invention thus makes it possible to produce a propeller wing or blade having a composite root which is both compact and preferably suitable for withstanding the different mechanical loads previously described. In particular, the fiber reinforcement portion of the root is made using 3D weaving and comprises a plurality of branches which are connected at their center to the fiber reinforcement portion of the aerodynamic profile. Therefore, the bulk of the root is mainly determined by the length of the branches, which makes it possible to obtain a more compact composite root than the roots of the prior art, which typically extend over the entire width of the lower part of the aerodynamic profile. In each branch, there are yarns, such as warp yarns, which are oriented in the spanwise direction of the wing or blade, which imparts good mechanical tensile and bending properties to the wing or blade when combined with 3D weaving.

[0015] Furthermore, the branching shape makes it possible to obtain a root having an axisymmetric or quasi-axisymmetric shape that is compatible with propeller rotation or pitch control systems.

[0016] Thus, by producing a fiber reinforcement in which the root is formed integrally with the aerodynamic profile, ie woven into a single piece, very good mechanical resistance is ensured in the entire piece, in particular in the connection between the root and the aerodynamic profile.

[0017] According to an embodiment of the method described in the present invention, densifying the fiber preform includes: placing the preform in an injection tool having the shape of the blade or the propeller blade to be manufactured; placing a removable insert element between the branches of the root preform part, and the densification also includes: injecting resin into the fiber preform retained in the injection tool; converting the resin into a matrix by heat treatment; and demolding the blade or the propeller blade, and the demolding includes: obtaining the removal of the insert element, thereby obtaining a root with multiple branches.

[0018] According to an embodiment of the method according to the invention, densifying the fiber preform comprises: placing the preform in an injection tool having the shape of the blade or propeller blade to be manufactured; placing a filling element between the branches of the root preformed portion, the densification further comprising: injecting a resin into the fiber preform retained in the injection tool; converting the resin into a matrix by a heat treatment; and demoulding the blade or propeller blade, thereby obtaining a root, the root comprising a skeleton, the skeleton comprising a plurality of branches, the filling element being bonded to the branches. The filling element can enhance the mechanical resistance to circumferential compression.

[0019] According to one aspect of the method according to the invention, the filling element consists of a fiber material selected from one of the following fiber materials: a three-dimensional fabric, a unidirectional laminate and a fiber mat.

[0020] According to one aspect of the method according to the present invention, the filling element is made of a metal material.

[0021] The present invention also has the following subject matter: a turboprop blade or propeller wing made of composite material, comprising a fiber reinforcement densified by a matrix, the blade or propeller wing comprising a root and an aerodynamic profile in the span direction, the fiber reinforcement comprising a fiber preform with three-dimensional weaving, a root preform part being located in the root, and an aerodynamic profile preform part being located in the aerodynamic profile, the root preform part and the aerodynamic profile preform part being connected to each other by three-dimensional weaving, characterized in that the root comprises a plurality of branches, and that the root preform part of the fiber preform comprises a plurality of branches, each of the plurality of branches extending in one branch of the root.

[0022] The present invention also has the following subject matter: a turboprop blade or propeller blade made of composite material, the turboprop blade or the propeller blade comprising a fiber reinforcement densified by a matrix, the blade or propeller blade comprising a root and an aerodynamic profile in the span direction, the fiber reinforcement comprising a fiber preform with three-dimensional weaving, wherein a root preform part is located in the root and an aerodynamic profile preform part is located in the aerodynamic profile, the root and the aerodynamic profile preform part being connected to each other by three-dimensional weaving, characterized in that the root has a bulb shape, the root comprises a skeleton comprising a plurality of branches, and the root preform part of the fiber preform comprises a plurality of branches, each of the plurality of branches extending in one branch of the skeleton of the root.

[0023] According to one aspect of the blade or propeller airfoil of the invention, the filling element consists of a fiber material selected from one of the following fiber materials: a three-dimensional fabric, a unidirectional laminate and a fiber mat.

[0024] According to another aspect of the blade or propeller airfoil of the present invention, the filling element is made of a metallic material.

[0025] The invention also covers an aircraft engine comprising a plurality of blades or propeller blades according to the invention and an aircraft comprising at least one such engine. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] [ Figure 1 ] Figure 1 is a schematic diagram illustrating 3D weaving of a fiber blank for manufacturing a blade,

[0027] [ Figure 2 ] Figure 2 is an enlarged scale weft cross-sectional view of an assembly of multi-layer yarns, which shows the cross-sectional view along the II-II Figure 1 Two non-interconnected parts are formed in the root of the blank,

[0028] [ Figure 3 ] Figure 3 It shows Figure 1 A perspective view of the forming of the root preform part of the fiber blank,

[0029] [ Figure 4 ] Figure 4 FIG. 1 is a diagram showing an injection tool and a Figure 3 A schematic exploded perspective view of a fiber preform placed inside the fiber preform.

[0030] [ Figure 5 ] Figure 5 It shows closed Figure 4 A perspective schematic diagram of an injection tool,

[0031] [ Figure 6 ] Figure 6 is a perspective schematic diagram of a blade made of composite material obtained according to an embodiment of the present invention.

[0032] [ Figure 7 ] Figure 7 is an injection tool and a Figure 3 A schematic exploded perspective view of a fiber preform placed inside it.

[0033] [ Figure 8 ] Figure 8 It shows closed Figure 7 A perspective schematic diagram of an injection tool.

[0034] [ Fig. 9 ] Fig. 9 is a perspective schematic diagram of a blade made of composite material obtained according to another embodiment of the present invention. DETAILED DESCRIPTION

[0035] The invention is generally applicable to different types of blades or propeller blades used in aircraft engines. The invention has advantageous and non-exclusive application in blades or propeller blades of large dimensions for incorporation into pivot or pitch systems. Such blades or propeller blades are generally provided with a root having a small volume (compact shape) and good resistance to tensile, bending and circumferential compression forces. In particular, the blade according to the invention can be formed: a blade for a ducted impeller (such as a fan blade) or a blade for a ductless wheel blade (such as a blade in an "open rotor" aircraft engine).

[0036] In the remainder of the description, the exemplary embodiments are described with respect to blades for turboprop engines. However, the exemplary embodiments are also applicable to propeller blades for aircraft.

[0037] Figure 1 A fiber blank 100 for shaping a fiber preform of a blade to be produced is represented very schematically.

[0038] like Figure 1 As schematically illustrated, the fiber structure blank 100 is obtained in a known manner by three-dimensional (3D) weaving with the aid of a jacquard loom on which a bundle of warp yarns 101 or strands made of multiple layers of yarns (several hundred yarns per layer) has been arranged, the warp yarns being connected by weft yarns 102. The fiber structure blank 100 is woven as a single piece, the blank being woven between a lower part 100c and an upper part 100d in a longitudinal direction D corresponding to the span direction of the blade to be manufactured. L The blade 100a extends between the leading edge 100a and the trailing edge 100b in a transverse direction D corresponding to the chord direction of the blade to be manufactured. T The blank comprises an aerodynamic profile 111 defining two faces 111e and 111f for forming the suction side and the pressure side of the blade, respectively, and a root 112 for subsequently forming the blade root and extending in the longitudinal direction D L Extending to the outside of the aerodynamic profile blank 111 and along the transverse direction D T Concave from the leading edge 100a and the trailing edge 100b.

[0039] In the example illustrated, the 3D weaving is woven using an "interlocking" weaving. Here, the term "interlocking" weaving should be understood to refer to a weaving in which each layer of weft yarns connects several layers of warp yarns, wherein all yarns in the same weft yarn column have the same movement in the weaving plane.

[0040] Other known types of three-dimensional weaving may be used, such as those described in particular in document WO 2006 / 136755, the content of which is hereby included by reference. This document describes in particular the production of a fiber-reinforced structure for a piece, such as a blade, in a single piece having a first weave at the core and a second weave at the skin, which allows a piece of this type to have the desired mechanical and aerodynamic properties.

[0041] In particular, the fiber blank according to the invention may be woven from carbon or ceramic fiber yarns (eg silicon carbide).

[0042] As fiber blanks of different thicknesses and widths are gradually woven, a certain number of warp yarns are no longer woven, which makes it possible to continuously and variably define the desired profile and thickness of the blank 100. An example of variable 3D weaving is described in document US2006 / 257260, in particular, the thickness of the blank can be changed between a first edge for forming a leading edge and a second edge of a smaller thickness for forming a trailing edge.

[0043] According to the present invention, during the weaving process, two non-interconnected elements 106 and 107 are made inside the root 112 of the fiber blank 100 located between two layers of consecutive warp yarns. The non-interconnected element 106 extends along a plane parallel to the surface of the fiber blank and over a non-interconnected area defined by a contour 106a, which locally divides the root 112 into two woven portions 113 and 114. Similarly, the non-interconnected element 107 extends in a plane parallel to the surface of the fiber blank and over a non-interconnected area defined by a contour 107a, which locally divides the root 112 into two woven portions 115 and 116. In addition, the non-interconnected element 106 extends from a first side edge 1120 of the root 112 in the transverse direction and extends a distance d 106 Smaller than the width I of the root 112 112 The interconnecting member 107 extends from the second side edge 1121 of the root 112 in the transverse direction and extends a distance d 107 Smaller than the width I of the root 112 112 Thus, a non-interconnected region 117 (ie, a region where the blank is 3D-woven throughout its thickness) exists in the root 112 between the two non-interconnected pieces 106 and 107 .

[0044] Depend on Figure 2 The 3D braiding pattern of a blank 100 using an interlocking braid is schematically represented. Figure 2 is the warp yarn profile in the root 112 of the blank 100 (including the non-interconnected parts 106 and 107) ( Figure 1In this example, the blank 100 includes: L The eight layers of warp yarns 101 are extended. Figure 2 In the non-interconnected area 117, the 8 layers of warp yarns are connected by weft yarns T 1 To T 8 The weft yarn is basically connected along the transverse direction D T At the level of the non-interconnected element 106, the woven portion 113 comprises four weft yarns T 1 To T 4 The four layers of warp yarns 101 are connected to each other, and the woven portion 114 includes four weft yarns T 5 To T 8 Similarly, at the level of the non-interconnected element 107, the woven portion 115 comprises four weft yarns T 1 To T 4 The four layers of warp yarns 101 are connected to each other, and the woven portion 116 includes four weft yarns T 5 To T 8 Four layers of warp yarns connected to each other.

[0045] In other words, the weft yarn T 1 To T 4 does not extend into the multiple layers of warp yarns of woven portions 114 and 116 and the weft yarns T 5 To T 8 The fact that it does not extend into the multiple layers of warp yarns of the woven portions 113 and 115 ensures that the non-interconnected elements 106 and 107 separate the woven portions 113 from 114 on the one hand and the woven portions 115 from 116 on the other hand.

[0046] Once the weaving is completed, the unwoven yarns around the fiber blank 100 are cut to extract the blank, and then the root of the blank is formed. In the example described here, the root 112 is formed by spreading the woven parts 113 to 116 in different directions, such as Figure 3 Typically, the braided portions of the root that are not interconnected are spread out in different directions to form an axisymmetric or quasi-axisymmetric root skeleton, such as, but not limited to, a cross or star shape.

[0047] Thus, a fiber preform 200 can be obtained, which is L The aerodynamic profile preformed portion 211 and the root preformed portion 212 are included. In the example described here, the root preformed portion has a Figure 4 The aerodynamic profile preformed portion 211 is formed in a cross or star shape with four branches 213 to 216 as shown in FIG. The aerodynamic profile preformed portion 211 is formed in a transverse direction D between the leading edge portion 211a and the trailing edge portion 211b.T The number of branches can vary. For example, the root of the blank can include 4 non-interconnected parts in order to obtain a root preform with six branches. Typically, the branches of the root preform are parallel to the transverse direction D T extends within the plane.

[0048] Then, the densification of the fiber preform is carried out. The densification of the fiber preform for forming a fiber reinforcement of the part to be manufactured includes filling the voids in the whole or part of the volume of the preform with the material constituting the matrix. This densification is carried out in a manner known per se according to the liquid technology (CVL). The liquid technology includes impregnating the preform with a liquid mixture containing a precursor of the matrix material. The precursor is usually in the form of a polymer (for example a high-performance epoxy resin) and can be diluted in a solvent where applicable. The preform is placed in a mold, which can be closed in a sealed manner with a shell having the shape of the molded final part. Next, the mold is closed again and a liquid matrix precursor (for example, a resin) is injected into the entire shell to pre-impregnate the entire fiber portion of the preform.

[0049] The conversion of the matrix precursor, ie its polymerization, is accomplished by thermal treatment, generally by heating the mould, and after removal of any solvent and crosslinking of the polymer, the preform remains in the mould in the same shape as the piece to be produced.

[0050] If a carbon or ceramic matrix is ​​formed, the heat treatment includes: pyrolyzing the precursor to convert the matrix into a carbon or ceramic matrix, depending on the precursor used and the pyrolysis conditions. For example, the ceramic liquid precursor (particularly SiC) can be a resin of the polycarbosilane (PCS) or polytitanium carbosilane (PTCS) or polysilazane (PSZ) type, while the carbon liquid precursor can be a resin with a relatively high char rate, such as a phenolic resin. Several consecutive cycles from impregnation to heat treatment can be performed to achieve the desired degree of densification.

[0051] According to one aspect of the invention, in particular if an organic matrix is ​​formed, the densification of the fiber preform can be accomplished via the well-known RTM (resin transfer molding) step. According to the RTM method, the fiber preform is placed in a mold having the outer shape of the piece to be produced. A thermosetting resin is injected into the interior space of the mold including the fiber preform. In order to control and optimize the impregnation of the preform with the resin, a pressure gradient is usually established in the interior space between the location where the resin is injected and the exhaust port.

[0052] like Figure 4As illustrated in the figure, here, the injection of the liquid matrix precursor mixture into the fiber structure and the conversion thereof into the matrix are completed in an injection tool 300, the injection tool comprising a first shell 310 and a second shell 320, the first shell comprising at its center: a first cavity 311 corresponding to the shape and size portion of the blade to be produced, the second shell comprising at its center: a second cavity 321 corresponding to the shape and size portion of the blade to be produced.

[0053] According to a first exemplary embodiment, removable insert elements 330 to 333 are placed between the branches 213 to 216 of the root preformed portion 212. In particular, the removable insert elements may be made of resin, a soluble salt core or metal.

[0054] like Figure 5 As illustrated in , once the tool 300 is closed, the first cavity 311 and the second cavity 321 of the first shell 310 and the second shell 320 together define an inner volume 301, which has the shape of the blade to be produced and in which the fiber preform 200 is placed. The fiber preform 200 can be compacted with the tool 300 closed in order to obtain a determined fiber content in the preform. In this case, the compacting pressure is applied to the shells 310 and 320, for example by a press. The compaction of the fiber preform can also be done in a separate tool before the preform is introduced into the injection tool.

[0055] The tool 300 also comprises means for performing the injection of a liquid matrix precursor and for converting the precursor into a matrix. More precisely, in the example described here, the first housing 310 of the tool 300 comprises an injection port 313 for allowing the injection of the liquid matrix precursor mixture into the fiber preform, and the second housing comprises an exhaust port 323 for interacting with a pumping system for evacuating the tool and sucking in air during the injection process. The injection tool 300 also comprises a lower part 340 and an upper part 350, between which the first housing 310 and the second housing 320 are placed, and the lower part 340 and the upper part 350 are equipped with a heating device ( Figure 5 not shown).

[0056] Once the tool 300 is closed, the blade is molded by impregnating the preform 200 with a thermosetting resin that polymerizes by heat treatment. For this purpose, the well-known injection molding or transfer molding process, the so-called RTM (resin transfer molding) is used. According to the RTM process, a resin 360 (for example a thermosetting resin) is injected into the internal space occupied by the preform 200 via the injection port 313 of the first shell 310. The port 323 of the second shell 320 is connected to the exhaust duct ( Figure 5323). This configuration allows a pressure gradient to be established between the lower portion of the preform 200, into which the resin is injected, and the upper portion of the preform located near the port 323. In this way, the resin 360 injected substantially flush with the lower portion of the preform will gradually impregnate the entire preform by circulating it all the way to the exhaust port 323, through which the excess is evacuated. Of course, the first housing 310 and the second housing 320 of the tool 300 may include multiple injection ports and multiple exhaust ports, respectively.

[0057] For example, the resin used may be an epoxy resin with a temperature rating of 180°C (the maximum temperature that can be tolerated without loss of properties). Resins suitable for the RTM process are well known. Preferably, they have a low viscosity to facilitate their infusion into the fibers. The choice of the temperature rating and / or chemical nature of the resin depends on the thermomechanical stresses to which the part is subjected. Once the resin has been injected into the entire reinforcement, it is polymerized by a heat treatment according to the RTM process.

[0058] After injection and polymerization, the blade is demoulded. The insert elements 330 to 333 are then removed in such a way as to obtain a blade root comprising a plurality of branches. Finally, the blade is trimmed to remove excess resin and the chamfers are machined. Since the molded part meets the required dimensions, no further machining is required.

[0059] The densification method described above is mainly used for producing blades or propeller blades made of organic matrix composites (OMC), carbon matrix composites (C / C) and ceramic matrix composites (CMC) using the fiber preforms of the invention.

[0060] like Figure 6 As illustrated in , a blade 10 is obtained, which is formed of a fiber reinforcement densified by a matrix, and which includes a root 12 formed by a root preformed portion 212 of a fiber preform 200 at its lower part, and includes an airfoil 11 formed by an airfoil preformed portion 211 of the fiber preform 200. The blade 10 includes: a leading edge 11a and a trailing edge 11b, which correspond to the leading edge 211a and the trailing edge 211b of the fiber preform 200, respectively. Here, the root 12 has a cross or star shape with four branches 13 to 16, wherein the branches 213 to 216 of the root preformed portion 212 extend into these branches, respectively. Therefore, the blade 10 includes a root 12, which has a compact shape suitable for incorporation into a rotary or propeller pitch system.

[0061] According to particular features, certain branches of the blade root may have a greater thickness and / or length than other branches, so as to be adapted to the forces experienced by the blade.

[0062] according to Figure 7 In another exemplary embodiment shown in FIG. 2 , filling elements 217 to 220 are placed between branches 213 to 216 of the root preform 212 of the fiber preform 200. The filling elements 217 to 220 differ from the previously described removable insertion elements 330 to 333 in that they are intended to remain in the final blade. The filling elements may consist of a fiber material that may be selected from one of the following fiber materials: a three-dimensional fabric, a unidirectional laminate, and a fiber mat. The filling elements may also be made of a metal material.

[0063] The fiber preform 200 equipped with filling elements 217 to 220 is placed in an injection tool 400 similar to the tool 300 already described, i.e. the injection tool comprises a first shell 410 and a second shell 420, the first shell comprising at its center a first cavity 411 corresponding to the shape and size portion of the blade to be produced, and the second shell comprising at its center a second cavity 421 corresponding to the shape and size portion of the blade to be produced.

[0064] like Figure 8 As illustrated in FIG. 4 , once the tool 400 is closed, the blade is molded by impregnating the preform 200 with a thermosetting resin that polymerizes by heat treatment. For this purpose, the well-known injection molding or transfer molding process, the so-called RTM (resin transfer molding) is used. According to the RTM process, a resin 460 (for example a thermosetting resin) is injected into the internal space occupied by the preform 400 via the injection port 413 of the first shell 410. The port 423 of the second shell 420 is connected to the exhaust duct ( Figure 5 423). This configuration allows a pressure gradient to be established between the lower portion of the preform 200 into which the resin is injected and the upper portion of the preform located near the port 423. In this way, the resin 460 injected substantially flush with the lower portion of the preform will gradually impregnate the entire preform by circulating all the way to the exhaust port 423, through which the excess is evacuated. Of course, the first housing 410 and the second housing 420 of the tool may include a plurality of injection ports and a plurality of exhaust ports, respectively. Once the resin has been injected into the entire reinforcement, it will be passed through a device equipped with a heating device ( Figure 7 The upper portion 450 and the lower portion 440 of the tool 300 (not shown) are polymerized by heat treatment according to the RTM process.

[0065] After injection and polymerization, the blade is demoulded, then trimmed to remove excess resin and chamfered. Since the molded part meets the required dimensions, no other machining is required.

[0066] As mentioned previously, blades or propeller airfoils made primarily of organic matrix composites (OMC), carbon matrix (C / C) composites and ceramic matrix composites (CMC) can therefore be produced from the fiber preform of the invention.

[0067] like Fig. 9 As illustrated in FIG. 1 , a blade 20 formed of a fiber reinforcement densified by a matrix is ​​obtained, which comprises in its lower part a root 22 formed by a root preform 212 of a fiber preform 200 and a wing 21 formed by a wing preform 211 of a fiber preform 200. The blade 20 comprises: a leading edge 21a and a trailing edge 21b, which correspond to the leading edge 211a and trailing edge 211b of the fiber preform 200, respectively. The root 22 has a bulb shape and comprises here a skeleton with four branches 23 to 26, wherein the branches 213 to 216 of the root preform 212 extend respectively, wherein the filling elements 217 to 220 are located between the branches 23 to 26. If the filling elements consist of a fiber material, they are also infiltrated by the resin injected into the tool and fixed to the branches 213 to 216 of the root preform 212 by co-densification. If the filling element is made of a metallic material, the filling element is bonded to the branches 23 to 26 during or after the polymerization of the resin injected into the tool. In addition, the adhesive may be deposited on the surfaces of the branches 213 to 216 of the root preform 212 in contact with the filling elements 217 to 220. Thus, the blade 20 includes a root 22 having an axisymmetric compact shape suitable for incorporation into a rotary or propeller pitch system.

[0068] The manufacturing method according to the invention can be used in particular for producing products having a Figure 6 and Fig. 9 The blades shown in FIG. 1 are turbine blades with more complex geometries.

Claims

1. A method for manufacturing a turboprop blade or propeller blade made of composite material, said turboprop blade or said propeller blade comprising a fiber reinforcement densified by a matrix, said method comprising: A fiber blank (100) is produced by three-dimensional weaving, the fiber blank being made into a single piece, the fiber blank having a longitudinal direction (D L ) and transverse direction (D T ) extends in a flat shape, the longitudinal direction (D L ) and the transverse direction (D T ) correspond to the span direction and the chord direction of the blade or propeller wing to be manufactured, respectively, the fiber blank (100) comprises a root portion (112) and an aerodynamic profile portion (111), the aerodynamic profile portion extending from the root portion of the fiber blank along the longitudinal direction (D L ) extends, and along the transverse direction (D T ) extends between the leading edge portion (100a) and the trailing edge portion (100b), shaping the fiber blank (100) to obtain a single-piece fiber preform (200) having the aerodynamic profile forming an aerodynamic profile preform (211) and the root forming a root preform (212), and Densifying the preform (200) by means of a matrix to obtain a blade or propeller blade (10) made of composite material having a fiber reinforcement consisting of the fiber preform and densified by means of the matrix and forming a single piece with an integrated root (12), The fiber blank is characterized in that the root portion (112) of the fiber blank comprises a plurality of non-interconnected parts (106, 107) extending along a plane parallel to the surface of the fiber blank (100), each non-interconnected part (106, 107) extending from an edge (1120, 1121) of the root portion (112) of the fiber blank along the transverse direction (D T ) is extended, and the extended distance (d 106 d 107 ) is smaller than the width of the root (l 112 ), each non-interconnected member (106, 107) separates two woven portions (113, 114, 115, 116) in the fiber blank (100), and shaping the fiber blank includes: orienting the woven portions (113, 114, 115, 116) separated by the non-interconnected members (106, 107) in different directions to form a root preform portion (212) including a plurality of branches (213, 214, 215, 216).

2. The method according to claim 1, wherein: Densifying the fiber preform (200) comprises: placing the preform in an injection tool (300) having the shape of the blade or the propeller blade to be manufactured; placing removable insert elements (330, 331, 332, 333) between the branches (213, 214, 215, 216) of the root preform part (212), the densification also comprising: injecting resin (360) into the fiber preform (200) retained in the injection tool (300); converting the resin into a matrix by heat treatment; and demoulding the blade (10) or the propeller blade, the demoulding comprising: removing the insert elements, thereby obtaining a root (12) having a plurality of branches (13, 14, 15, 16).

3. The method according to claim 1, wherein: Densifying the fiber preform (200) comprises: placing the preform in an injection tool (400) having the shape of the blade or the propeller blade to be manufactured; placing filling elements (217, 218, 219, 220) between the branches (213, 214, 215, 216) of the root preform part (212), and the densification also comprises: injecting resin (460) into the fiber preform retained in the injection tool; converting the resin into a matrix by heat treatment; and demoulding the blade (20) or the propeller blade to obtain a root (22), the root comprising a skeleton formed by a plurality of branches (23, 24, 25, 26), the filling elements being bonded between the branches of the skeleton.

4. The method according to claim 3, wherein: The filling elements (217, 218, 219, 220) consist of a fiber material selected from one of the following fiber materials: a three-dimensional fabric, a unidirectional laminate and a fiber mat.

5. The method according to claim 3, wherein: The filling element is made of metal material.

6. A turboprop blade or propeller blade (10) for an impeller, said turboprop blade or propeller blade being made of a composite material, comprising a fiber reinforcement densified by a matrix, said blade or propeller blade being slanted in the span direction (D L ) comprises a root (12) and an aerodynamic profile (11), the fiber reinforcement comprising a fiber preform (200) with three-dimensional weaving, a root preform part (212) being located in the root (12), and an aerodynamic profile preform part (211) being located in the aerodynamic profile (111), the root preform part and the aerodynamic profile preform part being connected to each other by three-dimensional weaving, characterized in that The root (12) comprises a plurality of branches (13, 14, 15, 16), and the root preform portion (212) of the fiber preform (200) comprises a plurality of branches (213, 214, 215, 216), each of the plurality of branches (213, 214, 215, 216) extending in the branches (13, 14, 15, 16) of the root (12).

7. A turboprop blade or propeller blade (20) made of composite material, said turboprop blade or propeller blade comprising a fiber reinforcement densified by a matrix, said blade or propeller blade having a spanwise direction (D L ) comprises a root (22) and an aerodynamic profile (21), the fiber reinforcement comprising a fiber preform (200) with three-dimensional weaving, a root preform part (212) being located in the root (12), and an aerodynamic profile preform part (211) being located in the aerodynamic profile (21), the root preform part and the aerodynamic profile preform part being connected to each other by three-dimensional weaving, characterized in that The root (22) has a bulb shape, the root includes a skeleton, the skeleton includes a plurality of branches (23, 24, 25, 26), filling elements (217, 218, 219, 220) are located between the branches, and the root preform part (212) of the fiber preform (200) includes a plurality of branches (213, 214, 215, 216), each of the plurality of branches (213, 214, 215, 216) extends in the branches (23, 24, 25, 26) of the skeleton of the root (22).

8. A blade or propeller blade according to claim 7, wherein: The filling elements (217, 218, 219, 220) consist of a fiber material selected from the group consisting of three-dimensional fabrics, unidirectional laminates and fiber mats.

9. The blade or propeller blade of claim 7, wherein: The filling element is made of metal material.

10. An aircraft engine comprising a plurality of blades or propeller blades according to any one of claims 6 to 9.

11. An aircraft comprising at least one engine according to claim 10.

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