Fabric and resin composite component

Abstract

The invention relates to a method for manufacturing a molded part and to a three-dimensional molded part itself comprising a composite material comprising a fibrous preform and a resin, said part having a cavity (230 ') filled with a porous material (50). The porous material includes an intumescent porous polymeric material.

Description

Technical Field

[0001] The present invention relates to the field of aircraft components such as propeller blades or vanes, which may be present in turboprop or aircraft turbine engines, including those with unducted propellers. The casings of aircraft turbine engines are also particularly targeted.

[0002] In the following the term "blade" covers both stationary vanes and aircraft propeller blades.

[0003] Typically, such aircraft components are made of metal. Although the aircraft components have good mechanical strength, they still pose the problem of relatively high mass.

[0004] In order to obtain lighter components, it is known to produce them by using composite materials, ie for example structural components having fiber reinforcements and a resin matrix. Background Art

[0005] Therefore, EP3511240 presents a solution for reinforcing the fiber structure of an aviation blade (or propeller blade) made of composite materials. This structure is woven into a single part, integrating an airfoil, a spar portion and a protruding portion. The fiber structure includes a decoupling region, which makes it possible to form a shell inside the fiber structure, into which a part of a reinforcing insert is inserted, and the reinforcing insert is a spar here, a part of which therefore extends into the interior of the airfoil at the decoupling region, and another part of which leads to the outside of the airfoil at the root edge of the airfoil. The protruding portion extends to the outside of the airfoil as an extension of the spar portion. The airfoil includes a skin at the decoupling region, which is decoupled relative to each other and fastens the spar portion. The skin defines two shells at the airfoil, respectively, and the two shells are present on either side of the spar portion and have their openings at the root edge of the airfoil. The final blade is a part with a cavity, in which an insert made of a traditional rigid foam in a solid form is introduced.

[0006] In the field of aviation turbine engines with shrouded blades or propellers, many turbine engines are also known through which a plurality of gas flows run, in particular with a primary flow and a secondary flow, or a dual flow.

[0007] Technical issues

[0008] For many years, at least in aviation twin-flow turbine engines, increasing the bypass ratio (the ratio between the flow rates of the primary and secondary flows) has been the solution favoured by engine manufacturers to improve engine performance and reduce its specific fuel consumption.

[0009] This results in an increase in the diameter of the equal-thrust blade assemblies of the turbine engine, in particular with regard to the first blade assembly where the air enters the turbine engine: the fan blades or propellers, and the associated straighteners (OGVs or outlet guide vanes).

[0010] For unducted architectures, this increase is even more significant.

[0011] However, these increases in size have the disadvantage of resulting in an increase in the mass of the blades and / or the casing, which is detrimental to the performance of the turbine engine.

[0012] So far, one solution for limiting this impact on mass has been to manufacture blades and / or shells in solid composite materials (3D woven composites via e.g. RTM processes - Resin Transfer Moulding or Resin Injection Moulding) instead of metallic materials (e.g. titanium).

[0013] However, taking into account the foreseeable dimensions of future blades, for example in unducted architectures of aviation turbine engines of the 'Open FAN', 'Unducted Single FAN' or 'Propfan' type, it would seem desirable to be able to increase this mass reduction.

[0014] One of the possible solutions to overcome this problem is to design and / or produce hollow aerospace components (referred to as hollow components).

[0015] However, during operation of an aircraft turbine engine, and if hollow components, in particular blades, are used, these hollow components are subject to significant pressure from the airflow along which the turbine engine moves to provide thrust. This pressure can deform the hollow components by crushing the cavities in the components and thus, for example, in fan blades, which can significantly reduce their efficiency due to deformation of the airfoil section of the component.

[0016] The cavity can be filled with porous materials such as high-density foams, which makes it possible to meet the needs of lightening and improving the mechanical characteristics of the part and limiting or even completely suppressing skin crushing.

[0017] However, during operation of the turbine engine, the components, in particular the blades or vanes, work mechanically, in particular or predominantly with bending stresses under the influence of the airflow. In order to limit the influence of these forces, it is known to add one or more inserts to form a reinforcement, as in EP3511240. In the case where the reinforcement is a spar or comprises a spar and the composite component is a blade, the spar can also serve as an attachment point for the blade on the disk of the turbine engine and thus makes it possible to create a connection between the aerodynamic skin of the blade, the porous material in the cavity and the rest of the turbine engine.

[0018] The production of hollow parts consisting of many sub-components is always difficult because it is tricky to manipulate them before they are solidified by resin. The assembly of the various sub-components must be very precise and repeatable so that the part meets the requirements without high scrap rates in manufacturing.

[0019] Supplying components made of conventional rigid foam in solid form and with precise geometrical dimensions, also for filling inserts with weak or even negligible mechanical properties in relation to the general behavior of the finished component, represents a considerable logistical and financial effort.

[0020] Furthermore, any reinforcement which may therefore be a spar is usually designed as a separate component, with the same disadvantages as rigid foam (sensitivity during assembly, logistical complexity, etc.).

[0021] There is a need to improve the compactness of such components and to reduce their mass, number of braided layers and manufacturing costs. Summary of the invention

[0022] In view of the prior art, the present application proposes a composite (molded) component and a method for manufacturing a composite component.

[0023] More specifically, the invention relates in particular to a component (which may be three-dimensional) comprising a composite material comprising a fabric and a resin, the component having at least one cavity filled with a porous material (also referred to as alveolar material); hereinafter, such a porous material comprises an expanded porous polymeric material, which is a foamed polymer (a foam made of a polymer). The fabric is formed by three-dimensional weaving. The component may have one cavity or several cavities.

[0024] Each cavity has a bottom and at least one opening, in particular one opening. The positioning of the at least one opening is suitable for improving the mechanical properties of the component and / or facilitating the introduction of the expanded porous polymeric material at the bottom of the cavity. The at least one opening is for example positioned opposite the bottom of the cavity.

[0025] The term "fabric" means a surface obtained by assembling threads or fibers that can be arranged in two rows of intersecting paths. The term thus encompasses a fiber preform or a woven preform. It can be any woven or non-woven material, woven or non-woven cloth, and is therefore an actual fabric.

[0026] The "fabric" or fiber structure, and therefore the components produced therefrom, may be formed using any type of weaving: two-dimensional (2D), and in particular three-dimensional (3D).

[0027] "Two-dimensional weaving" or "2D weaving" means a conventional weaving method in which each warp thread passes from one side to the other side of the threads of a single weft yarn layer.

[0028] “Three-dimensional weaving” or “3D weaving” means a weaving method in which at least some of the warp threads are entangled with the weft threads in multiple weft yarn layers.

[0029] The term "component" covers any type of component. It may be an unfinished component, such as a semi-finished component. It may be a preform: a preform of a finished component.

[0030] The term "foam" as used in the term expansion or expandable foam has the following meaning: a medium (a solid continuous phase in which a gas phase is dispersed in the form of pores) resulting from the expansion of an expandable paste capable of expanding to form a foam. The formation of the gas phase that emulsifies and produces the foam is the result of the expansion reaction of the paste previously present in the liquid phase. Thus, unlike conventional foams (hereinafter referred to as solid foams) that are supplied in solid form and therefore have their own shape before they are used in the production process, the "foam from expandable polymer" of the present invention will be supplied in liquid form (polymer paste), but becomes solid during the expansion reaction and does not have its actual shape until it solidifies and expands in the cavity of the component.

[0031] "Solid foam" means: a rigid foam that is processed directly into the final shape, such as the products used in the prior art. In contrast, the expanded foam used here makes it possible to "make up" any deviations from the geometric tolerances.

[0032] Among the advantages, the simplification of the manufacturing process will be noted. Other advantages are as follows.

[0033] In said component, the expanded porous polymeric material may in particular be polyurethane. Advantages: widely used material, well understood, cheap, very efficient in filling volumes / spaces.

[0034] Advantageously, the cavity is delimited by the composite material. More precisely, the walls of the composite material delimit the cavity.

[0035] Advantageously, the component comprises at least one insert, in particular a woven insert, for example a woven insert in three dimensions. The insert may be suitable for defining a reinforcement (also defined below as a possible spar). The insert is in particular arranged in one of the at least one cavity of the component.

[0036] Now, with respect to the method for manufacturing a component comprising a braid (which may be as described above), the method of the present invention provides at least a partial answer to the above-mentioned problem and thus presents these steps (which may be nested, i.e., performed at least partially together):

[0037] - a knitted component having integrated therein at least one cavity, for example one cavity or several cavities, each cavity having a bottom and at least one opening,

[0038] - placing the component in the first part of the injection mold,

[0039] - placing a soluble core or a removable demouldable core or a flexible film in the cavity, the soluble core or film (including its interior space) occupying the volume of said cavity,

[0040] - closing the injection mould by means of at least the second part of the injection mould,

[0041] - injecting resin into the braid of the component in order to form a woven component made of composite material,

[0042] - demoulding the part from the injection mold,

[0043] - dissolving the soluble core or removing the removable core or flexible membrane from the cavity, as the case may be,

[0044] - placing an expanding paste suitable for forming a porous material in the cavity,

[0045] - waiting for the paste to react to form (preferably completely form) said porous material in the cavity,

[0046] -Remove any excess porous material overflowing from the cavity, if any.

[0047] The waiting time will last for a time (tmin) of more than one second. The waiting time will depend on the precise reference of the expansion product used, the manufacturer's recommendations and production experience that allows adaptation to the geometry and volume to be filled. In general, the time varies from a few seconds to less than 5 minutes.

[0048] The removal of any excess porous material may comprise or consist of the final machining of the part, which allows obtaining a finished part (with the exact desired shape) or a semi-finished part (for example, it may be necessary to install certain reinforcements or apply surface treatments). It may also involve deburring, checking whether the part complies with the requirements (verification of the composite material, verification of the dimensions). All of this can therefore be defined as a finished part. If possible excess amounts are to be removed, the cavity is already rigid. The foam only needs to fill the cavity. Therefore, if excess expanding foam is to be removed, it is in principle advantageous to wait for the reaction to end so that this excess foam does not have to be eliminated several times.

[0049] Thus, after waiting for the paste to react (which allows the paste to become (preferably completely become) the porous material), it would be possible and applicable to:

[0050] - remove any excess intumescent material that has escaped from the cavity, and

[0051] - Check if the part meets the requirements (verify the composite material, verify the dimensions, etc.), then

[0052] -Complete the finishing of the parts.

[0053] In the above methods, as noted above, the porous material will usefully comprise an expanded porous polymeric material, which may thus be an expanded or expanded foam.

[0054] When using expanded polymer materials, the expansion reaction of which occurs during the densification of the braided preform by means of the resin may result in high porosity (bubbles in the material due to the release of gas produced by the expansion reaction of the foam), which can have a negative impact on the mechanical properties of the part.

[0055] The use of such expanded materials rather than solid foams of final dimensions may result in irregular shapes of the interior cavity of the component. Although these irregular shapes are less detrimental than deviations of the exterior surface (within the aerodynamic flow), they must still be kept under control.

[0056] All of these therefore present problems which the inventive solution attempts to address.

[0057] The weaving of the component (blank or preform) can be in three-dimensional form, which will help to obtain high-performance industrial components, such as blades. In order to best ensure the aforementioned functions of the "flexible membrane" (if used) in industry, it is proposed to use:

[0058] - an inflatable bladder, which will be inflated in the cavity, or

[0059] - Pre-molded parts (reusable or not) made of silicone or polyurethane elastomer.

[0060] Thus, the advantage of a suitable deformation of the flexible membrane necessary to install it in the cavity or even to remove it will be combined with a mechanical resistance suitable for the injection pressure and for maintaining the required volume of the cavity.

[0061] In order to facilitate the reinforcement of the braided composite part, while doing so at a favourable moment for easy implementation of said method, it is also proposed that the method defined herein further comprises, between the braiding of the part integrating the cavity and the step of housing the expansion paste in the cavity:

[0062] - weaving an insert for a part with a cavity (thus capable of being three-dimensional), said insert being suitable for defining a reinforcement (hereinafter also defined as a possible spar),

[0063] - Inserting the braided insert into the cavity of the component.

[0064] However, this solution requires the manufacture of the braided insert separately from the manufacture of the component with the integrated cavity.

[0065] In order to avoid this and to create an insert in this cavity by a local modification of the braid, it is also proposed that the braiding of the component consists of co-braiding with a braided insert (thus capable of being three-dimensional), which will then be integrated into the component. In other words, the braiding of the component (integrated cavity) will consist of co-braiding with a braided insert (thus capable of being three-dimensional), which will then integrate the braided insert so as to become a single component.

[0066] In general, and depending on the type of core chosen to form the cavity (soluble or removable), the geometry of the cavity and the need for reinforcements or spars, it will be possible to densify these subcomponents while preforming the part to be produced, rather than producing them during a separate pre-injection.

[0067] In general, all textiles may comprise an interweaving of threads divided into two categories: "warp threads", which are threads parallel to the selvedge of the fabric, and "weft threads", which are threads perpendicular to the warp threads and entangled with the warp threads in a pattern called a "weave", the simplest weave consisting of an alternation in which each weft thread passes successively over and under a warp thread, with an offset from one weft thread to another (a solution called a "plain weave").

[0068] Furthermore, it is assumed that the braiding of the component incorporating the cavity includes a decoupling that will facilitate the formation of the cavity or shell inside the fiber structure that is to form the braided composite component.

[0069] There are two possibilities for placing the intumescent paste in the cavity:

[0070] - introducing the paste directly into the cavity, in contact with the walls delimiting the cavity,

[0071] - Alternatively, a (or another) flexible membrane or hollow flexible bladder is placed in the cavity, the expanding paste (after introduction therein) being contained in this (another) flexible membrane or bladder, which forms the interface between the composite part and the paste and subsequently between the composite part and the expanding foam, and is permanently held in place in the mould. This may facilitate handling of the expanding paste and may reduce the risk of leakage.

[0072] The advantages of the various aspects of the method that have just been presented, besides the simplicity of implementation and the possibility of large-scale production, are those of the component itself that have also been presented.

[0073] With regard to the advantages already mentioned, the following are proposed as embodiments which can be optionally implemented independently or in combination, completely or partially, depending on the situation:

[0074] - placing of the expansion paste comprises introducing said expansion paste at the bottom of the cavity so that the expansion paste expands from the bottom towards the at least one opening,

[0075] - placing the expandable paste in the cavity after selecting an expandable polymer as the expandable paste, said expandable polymer releasing gas during the polyaddition reaction to form said porous material which will then be dense in the cavity (well controlled process and continuously reproducible),

[0076] - Polyurethane is chosen as expandable polymer which releases CO2 during the polyaddition reaction to form the dense porous material (well-controlled process that can be reproduced continuously, and initial paste that is not difficult to obtain).

[0077] "Dense" means filling the cavity uniformly and completely, while having a sufficiently high density to ensure good mechanical properties of the foam with respect to its functions detailed above. This density is still significantly lower than the other component materials of the blade assembly, and is preferably greater than 50 kg / m 3 , or even between 100kg / m 3 With 300kg / m 3 between.

[0078] As will be understood, the method presented above, together with all or part of its features, will allow the manufacture of parts for aviation turbine engines, in particular blade preforms. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] Other features, details and advantages of the present invention will become apparent upon reading the following detailed description of some non-limiting exemplary embodiments and upon analyzing the accompanying drawings, in which:

[0080] [ Figure 1 ] is a schematic diagram of a blade according to an embodiment of the present invention,

[0081] [ Figure 2 ]yes Figure 1 The leaves in Figure 1 The cross section in the section plane A;

[0082] [ Figure 3 ]yes Figure 1 The leaves in Figure 1 The cross section in the section plane B;

[0083] [ Figure 4 ]yes Figure 1 The leaves in Figure 1The cross section in the cutting plane C;

[0084] [ Figure 5 ]yes Figure 1 The leaves in Figure 1 A longitudinal cross-sectional view in a section plane D of ;

[0085] [ Figure 6 ]yes Figure 1 The leaves in Figure 1 A longitudinal cross-sectional view in the section plane E of ;

[0086] [ Figure 7 ]yes Figure 1 The leaves in Figure 1 A longitudinal cross-sectional view in a section plane F of ;

[0087] [ Figure 8 ] is a schematic perspective view of a fiber structure blank after cutting the outer loose wires;

[0088] [ Fig. 9 ] is a schematic perspective view of a fiber structure blank after cutting the loose wires present on the spar portion of the preform;

[0089] [ Fig.10 ] is a schematic perspective view of the obtained fiber structure and a view thereof being formed using a forming part;

[0090] [ Fig.11 ] schematically shows Figure 1 A variant of the blade in which the component is still only a fiber, i.e. in a preformed state;

[0091] [ Fig.12 ]yes Fig.11 The cross section of the blade in the section plane H;

[0092] [ Fig.13 ]、[ Fig.14 ]、[ Fig.15 ]、[ Fig.16 ],as well as[ Fig.17 ] schematically shows the successive steps of manufacturing a hollow fiber component in an injection mold, which steps consist of densification, which can be Fig.11 Densification of the preform,

[0093] [ Fig.18 ] schematically shows in the same cross-sectional view the process after the densification and after the supply of the expansion foam into the cavity remaining in the hollow component Fig.11 The status of the components;

[0094] [ Fig.19] schematically shows in the same cross-sectional view a preparation state for supplying the expansion foam into a cavity according to a variant,

[0095] [ Fig. 20 ] The same cross-sectional view is used again to schematically illustrate the Fig.19 After the expansion foam is added to the bladder placed in the cavity Fig.19 The status of the components in the DETAILED DESCRIPTION

[0096] The following drawings and description contain elements that may serve not only to provide a better understanding of the invention but also, where appropriate, to contribute to its definition.

[0097] The invention is generally applicable to the production of various parts, in particular propeller blades or vanes for aircraft engines. The blade according to the invention can in particular constitute a blade for a shrouded movable rotor, such as a fan blade, or a blade for an unshrouded movable rotor as in a so-called "open rotor" aircraft engine.

[0098] Figure 1 A blade 10 is shown which is intended to be fastened to an aircraft turbine engine.

[0099] Like any aerospace blade (or propeller blade) referred to herein, the blade 10 has a free edge or end 11d and, at the opposite end, a root 12 by which the blade is fixed to a rotor disk 101 of a turbine engine.

[0100] More precisely, the blade 10 comprises an airfoil 11, which is intended to be the aerodynamic part of the blade, and a root 12, which is formed by a portion of greater thickness, for example with a bulb-shaped cross section. A shank 13 can be inserted between the root 12 and the airfoil 11. The cross section of the airfoil 11 structure has a curved profile of variable thickness in a direction DT transverse to the longitudinal direction DL or the direction of elongation of the blade between its leading edge 11a and its trailing edge 11b. The airfoil 11 extends in the longitudinal direction DL between the root edge 11c (or the edge for attachment to the rotor disk 101) and the free edge (or top edge) 11d. The length of the root 12 extending in the transverse direction DT is less than the length of the root edge 11c of the airfoil 11.

[0101] like Figures 1 to 7 As shown in FIG. 1 , the blade 10 comprises a fiber reinforcement, which is referenced 20 in some of the figures and is densified by a resin matrix. The fiber reinforcement 20 comprises the following as a single part:

[0102] an airfoil structure 21 intended to form an airfoil of the blade 10 ,

[0103] a spar portion 22 extending inside the airfoil structure 21,

[0104] A bulge 24 , which forms the blade root 12 , extends outside the airfoil structure 21 as an extension of the spar portion 22 .

[0105] The spar portion 22 may have the following as a single part:

[0106] a portion 22a extending inside the airfoil structure 21, and

[0107] - a portion 22b which is located outside the airfoil structure 21 and which forms the bulge 24 and the shank 13 (if present) of the blade 10 .

[0108] The fiber reinforcement 20 mainly comprises a first portion 25 and a second portion 26 separated from each other by an intermediate region 27. The first portion 25 delimits one or more decoupling zones Zd inside the airfoil structure 21, extending in the longitudinal direction DL between the intermediate region 27 and a root edge 21c of the airfoil structure 21, and in the transverse direction DT between a leading edge 21a and a trailing edge 21b of the airfoil structure 21, the root edge of the airfoil structure corresponding to the root edge 11c of the airfoil 11, the leading edge and the trailing edge of the airfoil structure corresponding to the leading edge 11a and the trailing edge 11b of the airfoil 11, respectively. The first part 25 comprises a first skin 28 and a second skin 29, which are decoupled from each other and from the spar portion 22, which extend in the transverse direction between the front edge 21a and the rear edge 21b of the airfoil structure 21, and in the longitudinal direction between the middle region 27 and the root edge 21c of the airfoil structure 21, which skins 28 and 29 fasten the spar portion 22. The first skin 28 and the second skin 29 delimit inside the airfoil structure 21 a first shell 30 and a second shell 31, which are present on either side of the spar portion 22 in the transverse direction, the openings of which are located at the root edge 21c of the airfoil structure 21. A first shaped element 40 is present in the first shell 30. Similarly, a second shaped element 41 is present in the second shell 31.

[0109] Typically, shaped elements such as 40, 41 are referred to in the art as "cores", see below.

[0110] The shaped elements such as 40, 41 or cores may each typically be formed from a solid block, typically a rigid foam element made by moulding or by machining a block of material. It is possible to dissolve each core in the cavity or to remove it (take it out of the cavity).

[0111] As an alternative to the spar portion 22, according to e.g. Figures 11 to 17 In one embodiment schematically illustrated in FIG, an insert 300 (which may be defined as a reinforcing insert or stiffener) may extend inside the airfoil structure, inside which the insert will then be temporarily surrounded by a forming element or a pressurized membrane surrounding the insert 300, which occupies the remaining volume of the cavity 230'.

[0112] The portion 22 a and the protruding portion 24 or the portion 22 b may be presented as such an insert, corresponding to the insert 300 .

[0113] In this solution:

[0114] - the blade 10 is transformed into a blade or vane 10 ′,

[0115] - The fiber reinforcement 20 made of 3D woven material remains; it simply changes its reference number: 20 ′,

[0116] - the spar portion 22 is therefore replaced by at least one insert or reinforcement, for example 300, woven in 3D and ultimately made of the same composite material (resin+fiber) as the fiber structure 200', in the case where the fiber structure is not made of metal (which is possible), or can even be co-woven with said fiber structure,

[0117] The first shell 30 and the second shell 31 may be maintained or replaced by a single shell defined underneath by a cavity 230 ′ extending inside the airfoil 11 ′.

[0118] Especially suitable for these two situations and Figures 8 to 10 As shown in the example of FIG. 1 , the method according to the invention for manufacturing an aerospace component comprises producing a fiber structure that has not yet been impregnated with resin, for example a fiber structure 100 intended to form a fiber preform of the component to be produced.

[0119] The fiber structure blank 100 is obtained by three-dimensional (3D) weaving in a known manner using a loom, which may be a jacquard type loom, on which a bundle of warp threads or strands are arranged in multiple layers, each layer having hundreds of threads, and the warp threads are bound in place by the weft threads. The fiber structure blank 100 is woven as a single part. In this example, the blank includes an airfoil blank 111, a spar portion blank 122 and a protruding portion blank 112, the spar portion blank 122 extending in the transverse direction DT inside the fiber structure blank 100 at a distance from the front edge 100a and the rear edge 100b, and in the longitudinal direction DL, extending between the intermediate regions 103 respectively located between the root portion 100c and the free (or top) portion 100d of the fiber structure blank, and the protruding portion blank 112 extending as an extension of the spar portion blank 122.

[0120] In the example shown, the 3D knit is an "interlocking" knit. An "interlocking" knit is understood here to mean a knit in which each layer of weft threads is combined with several layers of warp threads, wherein all threads of the same weft column have the same movement in the plane of the knit.

[0121] Other known types of braiding may be used, in particular three-dimensional braiding, in particular those described in document WO 2006 / 136755. This document describes in particular the production of a fiber-reinforced structure for a component such as a blade, by braiding it as a single part, the component having a core braid of a first type and a skin braid of a second type, which makes it possible to give this type of component both the desired mechanical and aerodynamic properties.

[0122] The fiber blank according to the invention can in particular be woven from threads of carbon fibers or ceramic fibers (for example silicon carbide).

[0123] Thus, when the fiber blank is woven so that its thickness and width can vary as in the example, no specific number of warp threads may be woven, which makes it possible to define a continuously variable desired profile and thickness of the blank 100 .

[0124] Furthermore, during the weaving of the fiber blank, a decoupling 110 can take place within the fiber blank between consecutive warp thread layers in one or more decoupling zones Zd.

[0125] In the direction DL, the coupling zone Z1 in the fiber blank is extended by one or more decoupling zones Zd, so that if H11 is the length of the airfoil 11 , then H11 = Z1 + Zd.

[0126] More precisely, in the example (see Figure 8), the decoupling 110 extends between the middle region 103 and the root edge 100c of the fiber structure blank 100 in the longitudinal direction DL, and between the front edge 100a and the rear edge 100b of the fiber structure blank 100 in the transverse direction DT. The decoupling 110 separates the first and second portions present on either side of the spar portion blank 122 so as to form a first skin blank 104 and a second skin blank 105 that are decoupled relative to each other. The first skin blank 104 and the second skin blank 105 extend between the front edge 100a and the rear edge 100b of the fiber structure blank 100 in the transverse direction DT, and between the middle region 103 and the root edge 100c of the fiber structure blank in the longitudinal direction. The skin blanks 104 and 105 fasten the spar portion blank 122 and the bulge portion blank 112. The first and second skin blanks delimit inside the fiber structure blank 100 a first shell 130 and a second shell 131 , which are respectively present on either side of the spar portion blank 122 in the transverse direction DT.

[0127] Once the fiber structure blank 100 has been woven, the loose threads present outside the woven block are cut, for example using a water jet, so as to define the outer contour of the fiber structure, such as Figure 8 The loose threads present on the skin blanks 104 and 105 are also cut at the lower part of the fiber structure blank in order to release the bulge portion blank 112 and a portion of the spar portion blank 122 intended to subsequently form the blade shank. The loose threads present around the spar portion blank 122 and the bulge portion blank 112 are also cut by lifting the skin blanks 104 and 105, as shown in FIG. Fig. 9 For this purpose, a first slit 107 and a second slit 108 are formed between the skin blanks 104 and 105 .

[0128] like Fig.10As shown by way of example in , a fiber structure 200 woven as a single part is then obtained, which fiber structure in this example has an airfoil 211 extending in the longitudinal direction DL between a lower end 211c and an upper end 211d, and in the transverse direction DT between a leading edge 211a and a trailing edge 211b, a spar portion 222 and a bulge portion 212. The fiber structure 200 comprises one or more decoupling zones Zd extending in the transverse direction DT between a leading edge 211a and a trailing edge 211b of the airfoil 211, and in the longitudinal direction DL between the middle portion 203 and a root edge 211c of the airfoil 211. The spar portion 222 extends inside the airfoil 211 at one or more decoupling zones Zd, is arranged in the transverse direction DT backwards from the leading edge 211a and the trailing edge 211b, and in the longitudinal direction DL between the intermediate portion 203 between the lower edge 211c and the upper edge 211d of the airfoil 211 and the root edge 211c of said airfoil in which the opening of the spar portion 222 is located. The bulging portion 212 extends outside the airfoil 211 as an extension of the spar portion 222, the bulging portion 212 extending in the transverse direction DT over a length L212 that is less than the length L211 of the root edge 211c of the airfoil. The bulging portion 212 is intended to subsequently form the blade root 12. The airfoil 211 comprises a first skin 228 and a second skin 229 which are decoupled relative to each other at one or more decoupling regions Zd, the first skin and the second skin extending in the transverse direction DT between the leading edge 211a and the trailing edge 211b of the airfoil and in the longitudinal direction DL between the middle portion 203 and the root edge 211c of the airfoil, the skins 228 and 229 fastening the spar portion 222.

[0129] The first skin 228 and the second skin 229 define at least one cavity 230 inside the airfoil, which in the example is defined by a first shell 231a and a second shell 231b, which are respectively present on either side of the spar portion 222 in the transverse direction. The cavity 230 and therefore the first shell 231a and the second shell 231b in the example are open to the outside. In the example, this opening is located at the lower end of the airfoil 211.

[0130] In an alternative embodiment of the associated insert 300, the insert 300 may thus be made of metal, such as in Fig.11 , 12 As in the example components in , the insert therefore replaces the protrusion 212 and the component 222.

[0131] Therefore, in every case of weaving of a part using a composite material (resin + fiber) at the end of the manufacturing process, in particular as with the woven fiber structure blank 100 and the woven fiber structure 200, at the end of the process there will be a cavity 230 or 230' integrated into a single part in the woven structure.

[0132] Furthermore, through these examples of a possible integrated spar extending from the root 12 or a possible reinforcing insert 300 forming a stiffener or a possible spar, it is possible to:

[0133] - reinforcing the knitted component at the location of its cavity 230 or 230 ′,

[0134] - if necessary, adding or integrating a blade root 12,

[0135] - and does so using an insert 300 which can be integral with the woven fiber structure or added in a cavity thereof, such as 230 ′ in the example.

[0136] In other words, insert 300:

[0137] a reinforcement with or without root 12 manufactured separately (made of a suitable material such as metal or woven in two or three dimensions) so as to define a part having a cavity (for example 230 ′ in the example), subsequently inserted into this cavity after the desired preform ( 200 ′ in the example) has been woven,

[0138] - or will be integrated with said preform as a single part, the weaving of the part integrating the cavity (in the example 200 ′) thus comprising the co-weaving of such reinforcement; Fig.15 The insert denoted 300 ′ in FIG. 5 simulates and illustrates this assumption of a dry braided preform, which allows the reinforcement to be formed after the resin has been injected into the mold (see below).

[0139] In the second case, the co-weaving of the reinforcing insert (eg 300 ′) with the woven fiber structure can be carried out in the same way as the fiber structure blank 100 ; this is also true in the second case of separate weaving of the reinforcing insert 300 but without the cavity.

[0140] Subsequently, the shaping of the fiber structure 200 (which, in the example, makes it possible to obtain the aforementioned blade preform) will continue by means of the following operations:

[0141] - introducing at least one shaped element into the or each aforementioned cavity,

[0142] - and mounting the component, in this case the woven fiber structure 200 or 20', in a first part 301 of an injection mold 310 for the component in question (see for an example Fig.13 , 14 ).

[0143] The embossing mold part for the relevant part, namely the first part 301 of the injection mold 310, is Fig.13 It is represented as 330 in Chinese.

[0144] As an example, Figures 13 to 17 It is intended to aid understanding of the portion of the method associated with molding a component by injecting resin 60 into the center of a fiber of a fiber structure, such as 200 ′ in the example.

[0145] Thus, first a fiber structure (eg, 200' in this example) is placed in an imprinting mold portion 330; see Fig.14 Instances in .

[0146] Subsequently, a suitable core and / or flexible membrane and / or insert and / or stiffener and / or possible spar 300 may be inserted into the cavity (eg 230 ′ in the example).

[0147] exist Fig.15 In the figure, the presence of a pre-manufactured composite or metal reinforcement 300 is shown, or alternatively, a dry woven preform is shown that allows the reinforcement to be formed after the injection of the resin 60, and thus this dry woven preform may already be woven together with the rest of the woven fiber structure (represented as 300').

[0148] In addition, at least one soluble core or removable core (see Fig.10 40, 41 in the figure) or a flexible membrane 430' subjected to pressure in the cavity via an inlet 432 for pressurized gas is inserted into the or each aforementioned cavity (for example, 230' in the example), as Fig.15 The situation in the example.

[0149] exist Fig.15 In the example, we also showed:

[0150] - at the bottom of the figure, the case where the cavity 230' contains a removable inflatable membrane 430', and

[0151] At the top, alternatively, in the cavity 230 ′, a solid core 430 ″ of the same nature as the shaped elements 40 , 41 is inserted (arrow 434 ) around the insert or reinforcement 300 or 300 ′.

[0152] The core 430 ″ integrates a central volume 436 in the shape of (a portion of) an insert or reinforcement 300 or 300 ′ situated in the cavity 230 ′, which can therefore be engaged therein.

[0153] Thus, in one way or another, the volume of the or each aforementioned cavity (eg 230' in the example) will then be occupied by a core or equivalent and will be subjected to the pressure of the injected resin 60, which may now occur:

[0154] - inclusion of inserts or reinforcements within the fibers of the fiber structure (eg 200 ′ in the example), if it is a woven component, such as a dry woven preform 300 ′,

[0155] - but not in said cavity.

[0156] To this end, another embossing mold part 303 of the mold 310 having a suitable embossing cavity will close the mold, such as Fig.16 , and resin 60 will be injected under pressure (which may be at room temperature) into the two imprinting mold parts (arrows 438) within the preform in order to densify the preform and form a composite material.

[0157] When the mold is reopened (such as in Fig.17 ), the resin 60 has infiltrated into both imprinting mold parts but not into the cavity (eg, 230' in the example), thereby densifying the fiber structure and forming the aforementioned composite material.

[0158] The resulting blank for the component can subsequently be demolded and deburred.

[0159] If the cavity 230, 230' contains at least one core 430", the core is dissolved if it is soluble, or removed if it is a removable core or removable film 430'.

[0160] Since the cavities 230, 230' have become accessible, we will now be able to add an amount of expanded paste 50 suitable to occupy the entire available volume.

[0161] We then wait for the paste 50 to react to form a foam, an expanding paste suitable for filling the cavities and ensuring that the shape of the final part obtained is maintained during operation.

[0162] Any excess foam escaping from the cavity (if present) can then be removed, and the part can then be checked for compliance with the requirements (verification of composite material, dimensional verification), and the resulting composite part can be finished.

[0163] An advantage of adding the expansion paste 50 only after moulding and therefore after densification of the (each) braided part is that it provides precise control over the geometry of the cavity in addition to controlling the external geometry of the component.

[0164] As already mentioned, this therefore reduces the risk of:

[0165] - high porosity (gas bubbles in the material due to the release of gases produced by the expansion reaction in the foam), which negatively affects the mechanical properties of the component, and

[0166] - Irregularities in the shape of the internal cavity of the component.

[0167] Furthermore, such solutions where the cavity is filled with expanding foam have the advantage of reduced component costs compared to solid foams, since the cost per component of a dissolvable or removable core is generally lower.

[0168] Another advantage may be to ensure that the release of the gas causing the expansion of the foam 50 will not contaminate the resin 60 used to densify the composite, which may be the following chronological sequence: providing the expanding paste 50 - waiting - closing the mold - densification by injecting the resin 60, said contamination could lead to voids (bubbles) in the matrix of the composite material, with the result that the mechanical properties of the material are reduced.

[0169] If the cavity(ies) of the component must contain the insert 300 , the use of expanded paste 50 rather than solid foam also makes it possible to more easily avoid the typical incurring of separate weaving of the first and second aforementioned 3D weaving preforms (see above) in order to avoid creating assembly constraints.

[0170] By removing this constraint, it will then be easier to envision the aforementioned co-weaving possibilities:

[0171] - (each) second preform (and thus possible stiffeners and / or spar),

[0172] - with a first preform, for example a fiber structure 100,

[0173] - This is always done before moulding in the mould 310 , after which the expanding / foaming paste 50 is placed.

[0174] Subsequently, 3D weaving of the first preform and decoupling (zone Zd above) and local adaptation of the weaving pattern will make it possible to form said cavity, for example 230 or 230 ′. Thus, by local modification of the weaving pattern, it will be possible to create one or more spars or stiffeners in this cavity.

[0175] The expanding nature of the cellular material 50 will allow for a natural adaptation to all geometries of the cavity in the densified part by conforming to the contours at the ends of the cavity and around the stiffeners and / or spars if they are present.

[0176] Regarding the placement of the expansion paste 50, it can be specifically stipulated that:

[0177] - the (each) cavity, such as 230 or 230', has a bottom 49 and an opening 51, and

[0178] This placement consists in introducing the expansion paste at the bottom 49 of the cavity, so that the expansion paste 50 expands from the bottom 49 towards the opening 51 , thereby reducing the risk of excessive overflow outside the cavity.

[0179] If the intumescent paste 50 is to be used directly in contact with the fiber+resin composite, it is optionally contemplated to use a flexible membrane filled with the intumescent paste 50, such as a flexible (hollow) bladder, e.g. Fig.19 , 20 431 in the example.

[0180] Such a flexible membrane, hereinafter referred to as a “flexible bladder” in order not to be confused with a possible membrane 430 ′, is in principle thinner than the membrane 430 ′, since the injection of the resin 60 has already taken place and the integrity of the cavity is therefore already ensured.

[0181] If present, a flexible bladder such as 431 thus has the purpose of containing the expanded paste 50 and the subsequently expanded porous polymer produced thereby, thereby facilitating implementation. However, not using a bladder would have the advantage of more direct contact between the porous material, the fibers of the composite material and the resin, if these materials are compatible. If the materials are only slightly compatible, then it would be preferable to isolate the different components and therefore retain the use of a flexible bladder.

[0182] The choice between these two options may also be dictated by the mechanical strength of the interface created between the expanded porous material 50 and the fiber / resin composite. It may be necessary to ensure that the interface is in fact resistant to stresses and has a good service life. The solution without a flexible bladder seems to be more favorable in this respect, since it allows direct physicochemical contact between the expanded porous material 50 and the resin of the composite material.

[0183] In the case of a flexible bladder, the opening 51 must allow:

[0184] - inserting the flexible capsule 431 into the cavity;

[0185] - then adding an expansion paste 50 to the bottom 49 of this cavity in a bladder, so that the expansion paste 50 grows by expanding from the bottom of the cavity towards the opening 51 of said cavity, without creating a vacuum bag during the evolution of said expansion paste into foam, while pressing the bladder against the wall 237 of the cavity (see, for example, Fig. 20 ).

[0186] As an alternative to a flexible bladder 431 opening on the same side as the opening 51, as in Fig. 20 In the example of FIG. 4 , a closed capsule may be provided having only an inlet 433, the inlet 433 being suitable for supplying the expansion paste 50 into the capsule (see, for example, Fig.19 ).

[0187] In any case, once in place in the cavity, the flexible bladder will remain there permanently.

[0188] Polyurethane is a well-known expandable polymer that can be used as the expansion material 50 because it releases CO 2 during addition polymerization to form porous materials commonly used in the industry, such as dense foams.

[0189] In the context of the present invention, the parameters to be considered in selecting the expanded polymer for material 50 will advantageously be:

[0190] - mechanical properties of the material 50 after expansion (density, compressive strength, etc.) in order to ensure the functionality of the invention;

[0191] - Implement parameters (expansion time, expansion temperature) so as not to complicate assembly;

[0192] - Specific characteristics of the polymer: compatibility with the material of the bladder, if required, and with the material of the rotor disk if the rotor disk is a blade, etc.

[0193] As regards the injection of the resin 60 into the closed mould 310 and thus the densification of the fibre preform in question, if slits 107 and 108 are present on the leading edge 211a and the trailing edge 211b, said slits will preferably be stitched closed prior to densification, such densification consisting of filling the pores of the whole or part of the volume of the preform with the constituent materials of the matrix.

[0194] The matrix of the composite material can be obtained in a manner known per se according to a liquid process. The liquid process consists of impregnating the preform with a liquid composition containing an organic precursor of the matrix material. The organic precursor is generally in the form of a polymer, such as a resin, as mentioned above (the expression "organic precursor" is interchangeable), possibly diluted in a solvent. The mold 310 in which the preform is to be placed can be sealed closed, thus defining inside a housing having the shape of the desired final molded part.

[0195] Once the mold 310 is closed, a liquid matrix precursor (and thus, for example, a resin) may be injected throughout the shell to impregnate the entire fiber portion of the preform.

[0196] As is known, after removal of the solvent (if present) and crosslinking of the polymer, the conversion of the precursor into an organic matrix is ​​carried out, that is to say its polymerization (this may or may not be by heat treatment), the preform still remaining in the mold. The organic matrix may be obtained in particular from an epoxy resin, such as the high-performance epoxy resin sold under the reference PR 520 by the company CYTEC, the high-performance epoxy resin sold under the reference Resin "2896" by the company 3M, or from a liquid precursor of a carbon or ceramic matrix.

[0197] In the case of carbon or ceramic matrix formation, the heat treatment consists of pyrolyzing the organic precursors in order to convert the organic matrix into a carbon or ceramic matrix depending on the precursors used and the pyrolysis conditions. Several consecutive cycles from impregnation to heat treatment may be performed in order to achieve the desired degree of densification.

[0198] If it is desired to obtain a two-dimensional (2D) part instead of a three-dimensional part, this will be possible, in particular if a 2D fabric is covered on each mould part, or if, for a blade, the suction side of the blade is covered on the expanded paste 50 and the mould is then closed. Therefore, if a 2D weaving is planned, it is proposed to weave the suction side part separately from the pressure side part and produce them by co-firing (with a resin interface between the two parts) or by sewing before forming.

[0199] Furthermore, the densification of the fiber preform can be carried out by the well-known resin transfer molding process (hence the name RTM), in which a thermosetting resin is injected into the available internal space of the mold. A pressure gradient is usually established in this internal space between the point where the resin is injected and the orifice for discharging the resin, in order to control and optimize the impregnation of the preform with the resin.

[0200] With respect to placing any insert, such as 300, in a cavity that is to receive the insert, any retaining features (centering arms, etc.) necessary to properly position the insert in the cavity will be used, as necessary.

Claims

1. A three-dimensional component comprising a composite material, the composite material comprising a fabric and a resin, the component having at least one cavity (230, 230'), the at least one cavity being filled with a porous material (50), each cavity having a bottom (49) and at least one opening (51), the component being characterized in that the fabric is formed by three-dimensional weaving and the porous material comprises an expanded porous polymer material.

2. Component according to the preceding claim, characterized in that The cavity is defined by the composite material.

3. A component according to any one of the preceding claims, comprising at least one insert adapted to define at least one reinforcement.

4. Component according to the preceding claim, characterized in that The insert is arranged in one of the at least one cavity of the component.

5. A method for producing a composite component, comprising the following steps: - weaving the component while integrating therein at least one cavity (230, 230') having a bottom (49) and at least one opening (51), - placing the component in a first part (301) of an injection mould (310), - placing a soluble core or a removable demouldable core (40, 41, 430") or a flexible film (430') in the cavity (230, 230'), the soluble core or the removable demouldable core or the flexible film occupying the volume of the cavity, - closing the injection mold by means of at least a second part (303) of the injection mold, - injecting a resin (60) into the braided material in order to form a braided component made of composite material, - demoulding the component from the injection mold, - dissolving the soluble core or removing the removable core or flexible membrane from the cavity, as the case may be, - placing an expanding paste (50) suitable for forming a porous material in said cavity, - waiting for the paste to react to form the porous material in the cavity, - Removing any excess porous material overflowing from the cavity, if any.

6. The method according to claim 5, characterized in that The weaving includes weaving the component in a three-dimensional form.

7. The method according to claim 5 or 6, characterized in that: An inflatable bladder inflated in the cavity or a preformed part made of silicone or polyurethane elastomer is used as the flexible membrane.

8. The method according to claim 5, 6 or 7, further comprising between the steps of weaving of the component integrating the cavity (230, 230') and containing the expansion paste in the cavity: - weaving an insert (300') for a component having said cavity, - Inserting the braided insert into the cavity (230, 230') of the component.

9. The method according to claim 5, 6 or 7, characterized in that: The knitting of the component integrating the cavity comprises knitting together with a knitted insert (22), the component then integrating the knitted insert so as to become a single component.

10. The method according to any one of claims 5 to 9, characterized in that The weaving of the component integrating the cavity includes decoupling (110) within the component.

11. The method according to any one of claims 4 to 9, characterized in that The placement of the expansion paste (50) includes introducing the expansion paste into the bottom of the cavity (230, 230') so that the expansion paste expands from the bottom toward the at least one opening.

12. The method according to any one of claims 5 to 11, characterized in that The placement of the expansion paste (50) in the cavity (230, 230') includes the preselection of an expandable polymer that releases gas during a polyaddition reaction to form the porous material, which is dense in the cavity.

13. The method according to claim 12, characterized in that The selection of the expandable polymer includes selecting a polyurethane that releases CO2 during the polyaddition reaction to form the dense porous material (50).

14. The method according to any one of claims 5 to 11, characterized in that The porous material comprises an expanded porous polymeric material.

15. The method according to any one of claims 5 to 14, characterized in that For the placement of the expansion paste in the cavity: - introducing the paste (50) directly into the cavity, in contact with the walls (237) delimiting the cavity, - Alternatively, another flexible film or flexible capsule (431) is placed in the cavity, the expanding paste being introduced into this other flexible film or flexible capsule, the flexible film or flexible capsule (431) thus forming an interface between the composite part and the paste (50), and subsequently between the composite part and the expanding foam, and being permanently held in place in the cavity (230, 230').

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