Method for impregnating a fibrous preform using a permeable block, method for manufacturing a matrix reinforced by a fibrous preform, and permeable block

Abstract

The invention relates to a method for impregnating a fibrous preform by injection or infusion of an impregnation material, comprising the steps of: providing a mould (12) comprising at least two parts (12A, 12B); arranging a fibrous preform (10) and at least one block (24) permeable to the impregnation material in one part (12A) of the mould such that the at least one block (24) is positioned between at least one portion of the fibrous preform (10) and at least one inner portion of the mould (12); closing the mould (12); and impregnating the fibrous preform (10) with the impregnation material (28).

Description

Description Title of the invention: Method for impregnating a fibrous preform using a permeable shim, method for manufacturing a matrix reinforced by a fibrous preform, and permeable shim. Technical Field

[0001] This disclosure relates to a method of impregnating a fibrous preform by injecting or infusing an impregnating material, a method of manufacturing a matrix reinforced by a fibrous preform, and a shim permeable to an impregnating material. Prior art

[0002] The impregnation of a fiber preform by infusion or injection, for example by resin injection, known under the term "RTM injection" where the acronym RTM comes from the English "Resin Transfer Molding", generally consists of placing a fiber preform within a mold, then closing the mold and introducing an impregnation material into the mold containing the fiber preform.

[0003] WO2018 / 011526 or WO2018 / 234687 illustrate examples of implementation of such methods.

[0004] However, ensuring impregnation quality, i.e. homogeneous diffusion of the impregnation material within and around the fiber preform, without cavities, bubbles or other defects, and this in a repeatable manner from one operation to another, is a constant issue. There is therefore a need in this regard. Statement of the invention

[0005] One embodiment relates to a method for impregnating a fibrous preform by injecting or infusing an impregnating material, comprising the steps of providing a mold comprising at least two parts, the mold having at least one inlet orifice and at least one vent orifice, arranging a fibrous preform and at least one shim permeable to the impregnating material in a part of the mold so as to position the at least one shim between at least a portion of the fibrous preform and at least an internal portion of the mold, the shim being arranged in a passage of the impregnating material between the fibrous preform and the mold extending from the at least one inlet orifice and at least one vent orifice, at least one inlet port to at least one vent port, close the mold, and impregnate the fiber preform with the impregnation material.

[0006] Hereinafter, and unless otherwise indicated, "preform" means "fibrous preform". Hereinafter, and unless otherwise indicated, "wedge" or "permeable wedge" means "at least one wedge permeable to the impregnation material"; "mold portion" means "at least one mold portion"; "preform portion" means "at least one preform portion"; "mold parts" means "the at least two mold parts"; and "inlet" and "vent" mean "at least one inlet orifice" and "at least one vent orifice".

[0007] The impregnation material may be, for example, a polymeric material (for example, a thermosetting or thermoplastic resin), a ceramic, or a metal. For example, the shim is made of a material that is resistant to the processing temperatures of the impregnation material and to the physicochemical characteristics of the impregnation material.

[0008] For example, the mold has at least one inlet port (for introducing the impregnation material into the mold) and at least one vent port (for removing air and / or excess impregnation material from the mold), and the shim is disposed in a passage of the impregnation material between the preform and the mold, the passage extending from the at least one inlet port to the at least one vent port. The shim may extend over all or part of the passage, continuously or discontinuously. There may be a single shim or several separate shims. The passage may include any space between the mold and the preform, or bypass path of the preform outside the volume defined by the preform, within the mold, when the mold is closed. For example, the mold is closed when the parts of the mold are assembled together.For example, the mold may have two opposing sides, one side having at least one inlet port while the opposite side has at least one vent port. These two sides may be opposed in an axial direction extending from one of these two opposing sides to the other of these two opposing sides.

[0009] For the purposes of this disclosure, the shim is an element configured to hold the preform, at least a portion of the preform, in position relative to the mold, at least an internal portion of the mold, during the closing of the mold and the impregnation phase, and intended to be subsequently removed from the matrix resulting from the impregnation of the preform. In other words, the shim is configured to be arranged at an interface between the fiber preform and the mold and forms an impregnation aid element which is systematically removed from the final part.

[0010] The shim may be placed within the mold before placing the preform within the mold, after placing the preform within the mold, or simultaneously with the preform. According to yet another variant, at least one shim may be placed, then the preform, then another shim.

[0011] The permeability of the shim allows a flow of impregnation material to flow through the shim, on the one hand within the passage, and on the other hand from the shim towards the preform. By its presence, the shim ensures a minimum space between the preform and the internal wall of the mold and prevents the passage from being accidentally blocked, for example when closing the mold by an involuntary movement or deformation of the preform itself within the mold. By its permeability to the impregnation material, the shim ensures the circulation of a flow of impregnation material both within the passage and from the passage towards the preform. This can allow a certain control of the irrigation of the preform with impregnation material, thanks to which the quality and repeatability of the quality of the impregnation can be improved.The present shim can ensure a flow of impregnation material within the preform from the face of the preform in contact with the shim, which can contribute to homogenizing the diffusion of the impregnation material within the preform, and to circumventing possible local congestions of impregnation material within the preform, resulting for example from local variations in setting, for example from resin polymerization, likely to otherwise generate impregnation inhomogeneity. The shim can allow controlled and rapid diffusion of the impregnation material within the preform, at a speed better controlled with respect to the setting time, for example the polymerization time, of the impregnation material. The method using the shim can allow homogeneous and reproducible impregnation.

[0012] In some embodiments, the fibrous preform has only a plurality of warp fibers and a plurality of weft fibers, the warp fibers the plurality of warp fibers extending in a first direction and the weft fibers the plurality of weft fibers extending in a second direction perpendicular to the first direction, wherein the passage intersects the first and / or second direction.

[0013] By "perpendicular" is meant that the first direction and the second direction form an angle of 90° (ninety degrees of angle) plus or minus 40° between them. (forty degrees of angle). For example, the angle can be 90° during weaving. For example, the warp threads can undulate in the direction of the thickness, perpendicular to the first and second directions. For example, during the forming of the piece, this angle can be modified to achieve the shape of the final piece, and for example vary by plus or minus 30°.

[0014] The passage is intersecting, or forms a non-zero angle, with the first direction or with the second direction or with the first direction and with the second direction. For example, the passage may be perpendicular to one direction among the first and the second direction, and parallel to the other direction among the first and the second direction. In other words, the passage is not understood in a plane adjacent to the preform and parallel to the first direction and to the second direction. This ensures that the passage is not adjacent to a portion of the preform, and therefore a portion of the final part, where the weft and / or warp fibers are likely to be flush and to be weakened by the removal of the shim. Such an arrangement / orientation of the passage relative to the fibers ensures the integrity of the final part after impregnation, removal of the shim and possible machining of the portion of the part in contact with the shim at the mold outlet.In this way, only fiber ends, which are portions of fiber without structural function, are likely to be damaged or cut by the removal of the shim and possible subsequent machining.

[0015] In some embodiments, the shim is sandwiched between the mold and the fiber preform, and in contact with the mold and the fiber preform.

[0016] The shim is sandwiched between the preform and the mold and in contact with the preform and the mold. There is therefore no clearance between the preform and the shim on the one hand and between the shim and the mold on the other hand. For example, the mold has an inner face configured to cooperate with the shim while the fiber preform has an outer face configured to cooperate with the shim, the inner face and the outer face being opposite each other and facing each other when the fiber preform is arranged within the mold, and the shim is sandwiched between and cooperates with the inner face and with the outer face.

[0017] This ensures that the fibers are locked in position against the shim within the mold, and thus ensures that no fibers are likely to be introduced into a porosity or cavity of the shim during impregnation. Such an introduction could be likely to impact the permeability characteristics of the shim and disrupt the intended flow of the impregnation material, and hinder the impregnation of at least a portion of the preform. Such an arrangement of the shim relative to the mold and the preform makes it possible to avoid such introduction of fiber(s) and to avoid impregnation defects.

[0018] In some embodiments, the fiber preform may have at least one sacrificial edge configured to form, after impregnation, a sacrificial portion, the shim being disposed only between the at least one sacrificial edge and the at least one internal portion of the mold.

[0019] A sacrificial part is a part that is modified / removed by machining, for example by cutting or milling, from the die resulting from the impregnation of the preform.

[0020] By placing the shim only in contact with the sacrificial edges, it is possible to ensure that the portions of the matrix resulting from the impregnation of the preform, which are intended not to be modified at the end of the impregnation phase, are not impacted. Furthermore, a sacrificial edge may be a portion of the preform that is less regular than the rest of the preform, on the one hand where variations in the setting of the impregnation material are more likely to occur than in the rest of the preform, and on the other hand where an external flow of impregnation material is likely to penetrate better into the preform. This can improve the homogeneity and reproducibility of impregnation.

[0021] In some embodiments, the fiber preform may be configured to form a blade airfoil having a leading edge, a trailing edge, a tip, a root, a lower surface, and an upper surface, wherein the shim is only disposed between the at least one internal portion of the mold and all or part of a portion of the fiber preform configured to form the leading edge, the trailing edge, the tip, and / or the root.

[0022] Within a preform configured to form an aerodynamic profile, the portions of the preform configured to form the leading edge, the trailing edge, the head and / or the root may form sacrificial edges in whole or in part. The portions of the preform forming the intrados and the extrados are portions having a very fine geometry, which it is not desirable to disturb by the presence of a shim, and for which any subsequent machining phase is avoided. The method according to the present disclosure may be well suited for the production of aerodynamic profiles, which are large elongated parts requiring good control of the diffusion of the impregnation material over relatively short times compared to the setting time of the impregnation material.

[0023] In some embodiments, the shim may have a first face configured to cooperate with the mold (or the at least one internal portion of the mold) and a second face configured to cooperate with the fiber preform, the first face and the second face being opposite each other, the first face and the second face being spaced apart from each other by a distance greater than or equal to one millimeter (1.0 mm).

[0024] To measure the distance between the first and second faces, the minimum distance between these two faces is considered. Such a shim can ensure a minimum spacing between the preform and the mold of at least one millimeter, or even two millimeters, or even at least three millimeters. For example, the maximum distance between the first and second faces can be eighty millimeters (80.0 mm), for example fifty millimeters (50.0 mm), for example thirty millimeters (30.0 mm), for example ten millimeters (10.0 mm). The dimensions of the shim in the directions transverse to the direction extending from the first face to the second face (and vice versa), do not have any particular limit other than a minimum to ensure the mechanical strength required for handling the shim during its installation within the mold.Such a wedge can ensure a satisfactory flow section and flow rate of impregnation material through the wedge. This can improve the homogeneity and reproducibility of impregnation.

[0025] In some embodiments, the shim may have a first permeability to the impregnation material in the direction of flow from the at least one inlet port to the at least one vent port, and a second permeability in the direction of flow from the passage to the fiber preform, the second permeability being strictly lower than the first permeability.

[0026] Permeability is a physical parameter well known to those skilled in the art, expressed in square meters (m 2) in Darcy (D), which characterizes the ability of a medium or porous material to allow a fluid to pass through it under the effect of a pressure gradient or a gravity field. Permeability is linked to Darcy's law.

[0027] For example, the second permeability may be a permeability of the shim in all directions perpendicular to the direction of flow from the at least one inlet orifice to the at least one vent orifice, but not necessarily. Such a ratio between the first permeability and the second permeability may make it possible to ensure firstly a supply of impregnation material over the entire interface between the shim and the preform, and more generally over the entire passage within which the shim is arranged, and then a controlled diffusion from the shim to the preform. This may make it possible to improve the homogeneity and reproducibility of impregnation.

[0028] In some embodiments, the first permeability may be constant along the passage while the second permeability is variable along the passage.

[0029] For example, the second permeability may be greater in areas closer to the vent than to the inlet, and lower in areas closer to the inlet than the vent. For example, the second permeability may be a function of the areas of the preform with which the shim is in contact. For example, the second permeability may be a function of a general orientation of the flow of impregnation material from the inlet to the vent within the mold. By "general orientation" is meant the macroscopic orientation of the flow of impregnation material within the mold, for example in a straight line from the inlet to the vent, independent of the local orientations of the flow within the passage and the orientation of the passage.

[0030] For example, the second permeability can be scalable within the same wedge, or can be scalable by successively arranging different wedges, each presenting a different second permeability.

[0031] Such a second evolving permeability can allow fine adjustment of the flow rate of polymeric material within the mold, towards the preform. This can improve the homogeneity and reproducibility of impregnation.

[0032] In some embodiments, the impregnation material may be a resin, for example, a thermosetting or thermoplastic resin.

[0033] Such an impregnation process using a shim may be well suited for impregnating a fiber preform with a resin. In particular, the shim may be well suited for implementing the process with resin.

[0034] One embodiment relates to a method of manufacturing a matrix reinforced by a fibrous preform comprising the steps of impregnating a fibrous preform according to the method of impregnating a fibrous preform according to any one of the embodiments described herein, whereby a reinforced raw matrix is ​​obtained, and of machining at least a portion of the reinforced raw matrix in contact with the shim during the impregnation process.

[0035] By "machining" we mean any operation consisting of removing material using a machine tool, for example by cutting, drilling, planing, sanding, routing, milling, etc.

[0036] The part of the raw matrix which corresponds to the part of the solidified impregnation material in contact with the shim (i.e. integrating the shim, or adjacent to the shim during impregnation) is machined, in particular to remove imperfections resulting from the presence of the shim.

[0037] One embodiment relates to a shim permeable to an impregnation material configured to be disposed between a fibrous preform and a portion of a mold for impregnating the fibrous preform by injection or infusion within a passage of the impregnation material between the fibrous preform and the mold extending from at least one inlet orifice of the mold to at least one vent orifice of the mold.

[0038] The shim may be made of polymeric material, metal or ceramic. For example, the material of the shim may have a melting or glass transition temperature of at least ten degrees Celsius (10°C) higher than the maximum temperature of the resin during impregnation. The shim may be made of porous material and / or have a honeycomb structure. For the purposes of this disclosure, a pore has a dimension of the order of a nanometer while a honeycomb has a dimension of the order of a micrometer and more. For example, the shim may be formed by a spiral strip forming an openwork tube, the spacing between the turns forming the openings. For example, the shim may be manufactured by additive manufacturing, for example by depositing successive layers of wires deposited in a staggered pattern.For example, the shim may have, in cross section, a general grid shape forming a first alveolar structure, the walls of the grid themselves being permeable to the impregnation material, for example by having a second alveolar or porous structure finer than the first alveolar structure.

[0039] For example, the shim material may have a coefficient of thermal expansion that is 100% greater or less than the coefficient of thermal expansion of the impregnation material with which it is configured to be processed. Such a gap may facilitate the formation of a clearance between the impregnated die and the shim, whereby demolding and / or separation between the shim and the die may be facilitated. This may facilitate the repeatability of the quality of the die resulting from the process according to the present disclosure.

[0040] In some embodiments, the shim may have a length direction and a width direction perpendicular to the length direction, the shim having a first permeability to the impregnation material along the length direction and a second permeability to the impregnation material along the width direction, the second permeability being strictly lower than the first permeability.

[0041] For example, when the shim is disposed within the mold, at the interface between an internal portion of the mold and a portion of the preform, the length direction may correspond to the flow direction of the impregnation material within the passage from the inlet to the vent, while the width direction may correspond to the flow direction of the impregnation material from the passage to the preform. Brief description of the drawings

[0042] The object of this presentation and its advantages will be better understood by reading the detailed description given below of different embodiments given as non-limiting examples. This description refers to the pages of figures attached, on which:

[0043] [Fig. 1] Figure 1 represents a step of an impregnation process

[0044] [Fig. 2] Figure 2 represents a sectional view of Figure 1, according to plane B,

[0045] [Fig. 3] Figure 3 shows a detailed view of the wedge,

[0046] [Fig. 4] Figure 4 shows another step of the impregnation process, according to the same sectional view as Figure 2,

[0047] [Fig. 5] Figure 5 represents yet another stage of the impregnation process, and

[0048] [Fig. 6] Figure 6 represents a machining step of the reinforced raw matrix obtained after the step shown in Figure 6, at the end of the impregnation process. Description of the embodiments

[0049] The figures represent a mold, a wedge, and a fiber preform in a very schematic manner for the clarity of this presentation. The person skilled in the art will obviously have no difficulty transposing the teaching of this presentation to forms adapted for the manufacture of real parts with more complex geometries.

[0050] The method of impregnating a fiber preform by injection or infusion of an impregnation material will be described with reference to figures 1, 2, 4 and 5. Note that figure 2 is a view of figure 1 along the section plane B shown in figure 1. In the context of this impregnation method, a mold 12 is provided comprising at least two parts 12A, 12B.

[0051] Figures 1 and 2 represent a step of the impregnation process during which a fiber preform 10 and at least one shim 24 permeable to the impregnation material are placed in a part 12A of the mold 12 so as to position the at least one shim 24 between at least one portion of the fiber preform 10 and at least one internal portion of the mold 12. The mold 12 has an inlet orifice 14, for introducing an impregnation material into the mold. The mold 12 has a vent orifice 16 for evacuating air and / or excess impregnation material during impregnation. According to a variant not shown, the mold may comprise several inlet orifices and / or several vent orifices. In this example, the inlet orifice 14 and the vent orifice 16 are arranged on opposite sides 11A, 11B of the mold 12. In this example, the two sides 11A, 11B are arranged opposite each other in an axial direction X of the mold 12.More generally, for the purposes of this disclosure, the axial direction X of the mold is the direction which extends between any two opposite sides, these sides respectively presenting the inlet orifice and the vent orifice.

[0052] In this example, the preform 10 is configured to form a blade aerodynamic profile having a leading edge, a trailing edge, a tip, a root, a lower surface and an upper surface. The preform 10 has a portion (or edge) 10A configured to form the leading edge, a portion (or edge) 10B configured to form the trailing edge, a portion (or edge) 10C configured to form the tip and a portion (or edge) 10D configured to form the root. The mold 12 can be adapted to the preform 10 and have a portion (or edge) 13A configured to form the leading edge, a portion (or edge) 13B configured to form the trailing edge, a portion (or edge) 13C configured to form the tip and a portion (or edge) 13D configured to form the root. In this example, the inlet 14 is provided in the portion 13D configured to form the foot while the vent 16 is provided in the portion 13C configured to form the head.

[0053] In this example, the preform 10 is entirely received in the part 12A of the mold, and is flush with the opening of the part 12A configured to receive the second part 12B of the mold 12 for its closure (see figure 2). Any other configuration is conceivable. According to a variant not shown, the preform could only be received partially within a part of the mold, and the shim could extend in front of joint planes between two parts of the mold.

[0054] Passages 20 and 22, formed between the preform 10 and the internal walls of the mold 12, extend from the inlet 14 to the vent 16. In this example, the passage 20 extends, from the inlet 14 to the vent 16, along a part of the portion 10D configured to form the foot, all along the portion 10A configured to form the leading edge, and along a portion of the portion 10C configured for the head. The passage 22 extends in this example from the inlet 14 to the vent 16, along a portion of the portion 10D configured to form the root (distinct from the portion of the passage 20), all along the portion 10B configured to form the trailing edge, and along a portion of the portion 10C configured for the head (distinct from the portion of the passage 20). In this example, only two passages are provided.For example, no passage is provided between the portion 10E of the preform 10 configured to form the intrados and the mold 12 (and more particularly in this example the portion 13E of the mold 12 configured to form the intrados), nor between the portion 10F configured to form the extrados and the mold 12 (and more particularly in this example the portion 13F of the mold 12 configured to form the intrados), the corresponding portions 13E and 13F of the mold 12 being respectively in contact with the preform 10 on these portions 10E and 10F (see also figure 6). In general, the portions configured to form a finished surface at the outlet of the mold after impregnation are not in contact with a shim. Indeed, the presence of such a shim could lead to subsequent machining which could present a risk of degradation of the fibers (fiber cuts) of the preform and could impact the mechanical strength and / or the surface condition of the final part.According to a variant not shown, a single passage can be provided between the preform and the mold, or more than two passages.

[0055] The shim 24 may be arranged within the mold 12, in this example within the part 12A of the mold 12, before the preform 10, after the preform 10, or simultaneously with the preform 10. According to yet another variant, at least one shim (or part of the shim 24) may be arranged, then the preform 10, then another shim (or another part of the shim 24). In this example, the shim 24 is arranged within the passages 20, 22 and may extend continuously in the passages 20 and 22 from the inlet 14 to the vent 16. The shim 24 may form a single piece, or comprise several separate pieces.

[0056] The shim 24 is arranged in a passage 20, 22 of the impregnation material 28 between the fiber preform 10 and the mold 12 extending from the at least one inlet orifice 14 to the at least one vent orifice 16. In this example, the shim 24 is sandwiched between the mold 12 and the fiber preform 10, and in contact with the mold 12 and the fiber preform 10.

[0057] As shown in the cutaways of Figures 1, 2, 4 and 6, in this example, the fiber preform 10 has only a plurality of warp fibers FC and a plurality of weft fibers FT, the warp fibers FC the plurality of warp fibers FC extend in a first direction X1 and the weft fibers FT the plurality of weft fibers FT extending in a second direction Y1 perpendicular to the first direction X1. The passage 20, 22 intersects with the first and / or second direction X1, Y1. In this example, the portions of the passages 20, 22 along the portions 10D and 10C of the fiber preform 10 are parallel to the second direction Y1 and perpendicular, or substantially perpendicular, to the first direction X1, while the portions of the passages 20, 22 along the portions 10A and 10B of the fiber preform 10 are parallel to the first direction X1 and perpendicular to the second direction Y1.

[0058] In this example, the fiber preform 10 has at least one sacrificial edge configured to form, after impregnation, a sacrificial portion, the shim 24 being disposed only between the at least one sacrificial edge and the at least one internal portion of the mold. In this example, the portion 10A configured to form the leading edge, the portion 10B configured to form the trailing edge, the portion 10C configured to form the head and the portion 10D configured to form the root can each form a sacrificial edge. The shim 24 can be disposed only between the at least one internal portion of the mold 12 and all or part of a portion of the preform configured to form the leading edge, the trailing edge, the head and / or the root. In this example, the shim 24 is only disposed between the portions 10A, 10B, 10C, 10D of the preform 10 and the corresponding mold portions 13A, 13B, 13C, 13D, respectively.

[0059] The shim 24 may have a first face 24A configured to cooperate with the mold 12 and a second face 24B configured to cooperate with the preform 10, the first face 24A and the second face 24B being opposite each other, the first face 24A and the second face 24B being separated from each other by a distance D greater than or equal to two millimeters. The distance D may vary along the shim 24, but not necessarily. In this example, the distance D is constant over the entire extent of the shim 24, but according to a variant, this distance D may vary along the extent of the shim 24, along the passages 20, 22.

[0060] The shim 24 may have a first permeability P1 to the impregnation material in the direction S1 of flow from the at least one inlet orifice 14 to the at least one vent orifice 16, and a second permeability P2 in the direction S2 of flow from the passage 20, 22 to the fiber preform 10, the second permeability P2 being strictly less than the first permeability P1. For example, the second permeability P2 may be a permeability of the shim in all directions, perpendicular to the direction S1, but not necessarily. For example, P1 may be equal at 0.7 m 2 (seven tenths of a square meter) and P2 can be equal to 10.0 m 2 (ten square meters).

[0061] For example, the first permeability P1 may be constant along the passage 20, 22 (along the direction S1) while the second permeability P2 may vary along the passage 20, 22. For example, the portions 25a where the wedge 24 extends transversely relative to the general orientation I of the flow of impregnation material from the inlet 14 to the vent 16 within the mold 12, in this example the axial direction X, may have a second permeability P21 which may be equal to 10% of the first permeability P1, for example in order to offer a minimum of resistance to the flow of the impregnation material in this direction. For example, the portions 25b where the wedge 24 extends substantially parallel to the general orientation I of the flow of impregnation material from the inlet 14 to the vent 16 within the mold 12, in this example the axial direction X, may have a second permeability P22, for example equal to 50% of the permeability P1.According to another example, the second permeability P22 may increase in stages along the passage 20, 22 (along the direction S1 oriented from upstream to downstream). For example, the wedge 24 may have a first portion 25b1 having a second permeability P22a which may be equal to 30% of the first permeability P1 and a second portion 25b2, downstream of the first portion 25b1 within the passage 20, 22, having a second permeability P22b which may also be 60% of the first permeability P1. This can make it possible to quickly bring the impregnation material along the entire interface of the shim 24 with the preform 10, and then ensure diffusion of the impregnation material within the preform 10 from the interface with the shim 24. According to yet another variant, the second permeability P22 can have more than two levels, or even vary continuously, or even vary in ratios different from those mentioned in the example above.

[0062] In other words, the shim 24 is a shim permeable to an impregnation material configured to be arranged between a fiber preform 10 and a portion of a mold 12 for the impregnation of the fiber preform 10 by injection or infusion within a passage 20, 22 of the impregnation material 28 between the fiber preform 10 and the mold 12 extending from at least one inlet orifice 14 of the mold to at least one vent orifice 16 of the mold 12.

[0063] Figure 3 shows in more detail a perspective sectional view of the shim 24. In this example, the shim 24 is manufactured by additive manufacturing by depositing successive layers of wires 27 deposited in a staggered pattern. The shim 24 may have, in transverse section, a general grid shape forming a first honeycomb structure associated with the first permeability P1, the walls of the grid themselves being permeable to the impregnation material, for example by having a second alveolar or porous structure finer than the first alveolar structure and defining the second permeability P2. The magnifying glass L represents a magnified view of the walls of the wedge 24 showing the porous structure of the latter. In this example, all the walls of the grid shape of the wedge 24 have the same second alveolar or porous structure.

[0064] The shim 24 may have a length direction Lo and a width direction La perpendicular to the length direction Lo, the shim 24 having the first permeability P1 to the impregnation material along the length direction Lo and the second permeability P2 to the impregnation material along the width direction La, the second permeability P2 being strictly less than the first permeability P1. In this example, the shim 24 has a thickness direction Lp and a permeability to the impregnation material along the thickness direction Lp equal to the second permeability P2. When the wedge 24 is arranged within the mold 12, the length direction Lo extends parallel to the direction S1 of the flow from the at least one inlet orifice 14 to the at least one vent orifice 16 and the width direction La extends parallel to the direction S2 of the flow from the passage 20, 22 to the fiber preform 10.

[0065] The relative orientation of the internal structure of the wedge 24 with respect to the directions Lo, La and / or Lp as shown in FIG. 3 is not limiting, any other orientation being possible.

[0066] Figure 4 represents a step where the mold 12 is closed, in this example using the second part 12B.

[0067] Figure 5 shows a step following the step of closing the mold 12, where the fiber preform 10 is impregnated with an impregnation material 28, in this example resin 28. The arrows represent the direction of the flow of impregnation materials at the inlet 14 and the vent 16 of the mold 12.

[0068] At the end of the impregnation process as described with reference to figures 1, 2, 4 and 5, a raw matrix 50 reinforced by a fiber preform is obtained. In this example, the raw matrix has a portion 50A configured to form a leading edge and corresponding to the portion 10A of the preform 10, a portion 50B configured to form a trailing edge and corresponding to the portion 10B of the preform 10, a portion 50C configured to form a head and corresponding to the portion 10C of the preform 10 and a portion 50D configured to form a foot and corresponding to the portion 10D of the preform 10. These portions 50A, 50B, 50C and 50D may form sacrificial parts of the raw matrix 50. The faces 50E and 50F respectively form an intrados and an extrados of aerodynamic profile. This impregnation process may form the first step of a method for manufacturing a matrix reinforced by a fiber preform. A following step of the manufacturing method may comprise machining at least a portion of the reinforced raw matrix 50 in contact with the shim 24 during the impregnation process. Figure 6 represents such a machining step. In this example, the machining is a milling of the portion 50A of the reinforced raw die 50, this portion 50A comprising the shim 24, using a milling cutter 60. The machining makes it possible to remove the shim 24 from the die 50. The portions 50B, 50C and 50D can be machined in the same way as the portion 50A.

[0069] Although the present invention has been described with reference to specific embodiments, it is obvious that modifications and changes may be made to these examples without departing from the general scope of the invention as defined by the claims. In particular, individual features of the various illustrated / mentioned embodiments may be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

[0070] It is also obvious that all the characteristics described with reference to a method are transposable, alone or in combination, to a device, and conversely, all the characteristics described with reference to a device are transposable, alone or in combination, to a method.

Claims

Claims

1. A method of impregnating a fiber preform by injecting or infusing an impregnating material, comprising the steps of: - providing a mold (12) comprising at least two parts (12A, 12B), the mold (12) having at least one inlet orifice (14) and at least one vent orifice (16), - arranging a fibrous preform (10) and at least one shim (24) permeable to the impregnation material in a part (12A) of the mold so as to position the at least one shim (24) between at least one portion of the fibrous preform (10) and at least one internal portion of the mold (12), the shim (24) being arranged in a passage (20, 22) of the impregnation material (28) between the fibrous preform (10) and the mold (12) extending from the at least one inlet orifice (14) to the at least one vent orifice (16), - close the mold (12), and - impregnate the fiber preform (10) with the impregnation material (28).

2. A method of impregnating a fiber preform according to claim 1, wherein the fiber preform (10) has only a plurality of warp fibers (FC) and a plurality of weft fibers (FT), the warp fibers (FC) the plurality of warp fibers (FC) extending in a first direction (X1) and the weft fibers (FT) the plurality of weft fibers (FT) extending in a second direction (Y1) perpendicular to the first direction (X1), wherein the passage (20, 22) intersects with the first and / or the second direction (X1, Y1).

3. A method of impregnating a fiber preform according to claim 1 or 2, wherein the wedge (24) is sandwiched between the mold (12) and the fiber preform (10), and in contact with the mold (12) and the fiber preform (10).

4. Method for impregnating a fiber preform according to any one of claims 1 to 3, in which the fiber preform (10) has at least one sacrificial edge (10A, 10B, 10C, 10D) configured to form, after impregnation, a sacrificial part (50A, 50B, 50C, 50D), the shim (24) being arranged only between the at least one sacrificial edge (10A, 10B, 10C, 10D) and the at least one internal portion of the mold (12).

5. A method of impregnating a fiber preform according to any one of claims 1 to 4, wherein the fiber preform (10) is configured to form a blade aerodynamic profile having a leading edge, a trailing edge, a head, a root, a lower surface and an upper surface, wherein the wedge (24) is only disposed between the at least one internal portion of the mold (12) and all or part of a portion (10A, 10B, 10C, 10D) of the fiber preform (10) configured to form the leading edge, the trailing edge, the head and / or the foot.

6. Method for impregnating a fiber preform according to any one of claims 1 to 5, in which the shim (24) has a first face (24A) configured to cooperate with the mold (12) and a second face (24B) configured to cooperate with the fiber preform (10), the first face (24A) and the second face (24B) being opposite each other, the first face (24A) and the second face (24B) being distant from each other by a distance (D) greater than or equal to one millimeter.

7. A method of impregnating a fibrous preform according to any one of claims 1 to 6, wherein the shim (24) has a first permeability to the impregnation material in the direction (S1) of flow from the at least one inlet orifice (14) to the at least one vent orifice (16), and a second permeability in the direction (S2) of flow from the passage (20, 22) to the fibrous preform (10), the second permeability being strictly lower than the first permeability.

8. An impregnation method according to claim 7, wherein the first permeability is constant along the passage (20, 22) while the second permeability is variable along the passage (20, 22).

9. A method of impregnating a fiber preform according to any one of claims 1 to 8, wherein the impregnating material is a resin (28).

10. A method of manufacturing a matrix reinforced by a fibrous preform comprising the steps of: - impregnating a fibrous preform (10) according to the method of impregnating a fibrous preform according to any one of claims 1 to 9, whereby a reinforced raw matrix (50) is obtained, and - machining at least a portion (50A, 50B, 50C, 50D) of the reinforced raw matrix (50) in contact with the shim (24) during the impregnation process.

11. A wedge (24) permeable to an impregnation material configured to be disposed between a fibrous preform (10) and a portion of a mold (12) for impregnating the fibrous preform by injection or infusion within a passage (20, 22) of the impregnation material (28) between the fibrous preform (10) and the mold (12) extending from at least one inlet orifice (14) of the mold to at least one vent orifice (16) of the mold (12).

12. Wedge (24) according to claim 11, having a length direction (Lo) and a width direction (La) perpendicular to the length direction (Lo), the wedge (24) having a first permeability to the impregnation material along the length direction (Lo) and a second permeability to the impregnation material along the width direction (La), the second permeability being strictly lower than the first permeability.

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