Blade reinforcement element manufactured using pre-compaction

Abstract

The invention relates to a method for manufacturing a fibrous preform (10) of a reinforcing element for a turbine engine blade, comprising: - producing a fibrous blank (100) by 3D weaving between a plurality of warp yarns (1001) and a plurality of weft yarns (1002), - pre-compacting the fibrous blank (100) in a pre-compaction tool (5), - removing the original surface (103) of the fibrous blank (100) by water jet cutting while pre-compacting the fibrous blank (100) in the pre-compaction tool (5), - taking the pre-compacted fibrous blank (100') out of the pre-compaction tool (5), - compacting the pre-compacted fibrous blank (100') to obtain the fibrous preform (10) of the reinforcing element.

Description

Technical Field

[0001] This invention relates to a reinforcing element for a composite material blade used in a turbine engine or propeller engine. The composite material blade may be, for example, a fan blade or an outlet guide vane (referred to as an OGV). Background Technology

[0002] To obtain lightweight turbine engine blades with excellent thermomechanical properties, the blades are typically made of composite materials, i.e., materials containing fiber reinforcements densified by a matrix (e.g., an organic matrix). Furthermore, the non-structural parts of the blade can be hollow to further reduce its mass.

[0003] Document FR 3 063 514 A1 describes an example of a ducted turbine engine rectifier blade extending radially between an inner platform and an outer platform. The blade is secured to the inner casing of the turbine engine via the inner platform and to the outer casing via the outer platform. The fiber reinforcement of the blade body has an end portion encompassing two sections separated from each other until they reach a free end. The blade also includes an insert called a "gap filler" or "roving" for filling the gap at the junction of the two separated sections. This insert can be manufactured, in particular, using shaped braided fabric.

[0004] Such turbine engine blades can belong to, for example, two-flow turbine engines, where the mass of air drawn in by the fan is distributed between the primary and secondary flows in a well-known manner. The bypass ratio / split rate of a turbine engine corresponds to the ratio of the primary flow rate to the secondary flow rate. To improve the performance of a turbine engine and reduce its fuel consumption, increasing this bypass ratio is beneficial. However, to maintain similar engine thrust, this increase in bypass ratio requires increasing the blade height, especially the height of the fan blades and associated rectifier blades. For ductless / unsplit turbine engines, this increase in height is more significant because the blade size is already large and the rotational speed is relatively low.

[0005] Therefore, the inserts described above must meet the geometric and structural constraints of these new blades. Consequently, the inserts must have a more elongated, outwardly flared shape, as well as steeper thickness variations, to accommodate the new blade geometry. However, such a shape cannot be achieved using existing technologies, including inserts made by weaving.

[0006] Furthermore, in ductless turbine engines, blades (especially rectifier blades) are attached to the turbine casing only through their inner radial ends located at the blade root. This results in all forces being transmitted to the blade root region, leading to high stress in the composite components at the blade root. Known inserts fail to adequately reinforce the blade root region locally, thus failing to sufficiently limit cracking and stress in the fiber-reinforced material at the separated sections under tensile, compressive, and bending stresses. Moreover, known inserts made of braided fabric have insufficient stiffness, failing to adequately improve the overall blade stiffness. This increases the risk of blade buckling and is detrimental to rectifier frequency settings. Summary of the Invention

[0007] To overcome the above-mentioned drawbacks, the present invention proposes to manufacture a reinforcing element that can, on the one hand, realize the function of inserts known in the prior art, and on the other hand, realize the function of a spar / truss, even if the reinforcing element has a very outward-expanding geometry.

[0008] Therefore, the present invention provides a method for manufacturing a fiber preform for a reinforcing element for, for example, a turbine engine blade, the method comprising the following steps: - A fiber preform is produced by three-dimensionally weaving multiple warp yarns extending along a first direction and multiple weft yarns extending along a second direction intersecting (e.g., perpendicular to) the first direction. The fiber preform extends along the first direction between a reference surface and a pristine surface, and extends along a third direction intersecting (e.g., perpendicular to) the first and second directions between the two surfaces to be formed. - The original surface of the fiber blank is removed by water jet cutting to produce a clean surface. - Arrange the fiber preform, including a clean surface, in a compaction tool to obtain a fiber preform with the shape of the reinforcing element to be obtained and a defined volumetric fiber content. The method is characterized by further including: - Before removing the original surface of the fiber preform, the preform is arranged in a precompacting tool, the preform comprising a receiving cavity defined by a base and two clamps extending from the base, the spacing between the two clamps being adjustable. The fiber preform is arranged in the receiving cavity of the precompacting tool such that a reference surface of the preform is arranged to contact the base, and then... - Adjust the clamps of the precompacting tool so that the cavity of the precompacting tool has the shape of the fiber preform of the reinforcing element to be obtained, so as to precompact the fiber blank, the surface of the blank to be formed is arranged to contact the clamps, and the original surface of the fiber blank is in a free state. The step of removing the original surface is performed simultaneously with the precompaction of the fiber blank in the precompaction tool, and after the step of removing the original surface, the precompacted fiber blank is removed from the precompaction tool and then placed in the compaction tool.

[0009] Therefore, the preforms of the reinforcing element are manufactured using a three-dimensional fiber braiding technique, which gives the reinforcing element excellent rigidity, especially in the radial direction relative to the turbine engine axis. Furthermore, the interface / coupling between the three-dimensional braiding of the reinforcing element and the three-dimensional braiding of the rest of the blade is more robust and strong.

[0010] By cutting the fiber preform of the reinforcing element during precompaction, cutting precision is greatly improved, enabling the acquisition of more complex reinforcing element shapes that are more suitable for next-generation blades. In fact, if cutting is performed in a conventional manner without precompaction, this step causes the fiber preform to deform during cutting, resulting in a deformed clean surface that deviates significantly from the desired geometry.

[0011] The fiber preform can be pre-compacted to obtain an outwardly flared shape on a clean surface. The fiber preform of the reinforcing element can have an outwardly flared shape. Along the length of the first direction D1 of the reinforcing element preform, the thickness of the fiber preform of the reinforcing element in the third direction D3 can be increased by at least 200% over a distance of less than 50%.

[0012] According to a particular embodiment of the invention, the fiber preform is obtained by water jet cutting of the fiber strip produced by three-dimensional weaving at the loom exit.

[0013] According to another specific embodiment of the invention, the reference surface and the original surface of the fiber blank comprise the same number of warp yarns.

[0014] Therefore, the resulting fiber blank does not expose the warp yarns: thus production is simpler and faster, and the risk of defects appearing in the blank after cutting off the exposed yarns is limited.

[0015] According to another specific embodiment of the invention, the fiber preform includes a first portion extending from a reference surface, the first portion having a greater compaction capacity than a second portion extending from the original surface.

[0016] According to another specific embodiment of the invention, the average diameter of the weft yarns in the second part of the blank is greater than the average diameter of the weft yarns in the first part of the blank.

[0017] According to another specific embodiment of the invention, the water jet cutting used to remove the original surface follows a non-linear profile.

[0018] According to another specific embodiment of the invention, the fiber preform is arranged in a precompacting tool such that two original side surfaces of the fiber preform opposite each other in the second direction are in a free state. When the fiber preform is precompacted in the precompacting tool, these two original side surfaces are removed by water jet cutting.

[0019] Therefore, the cutting of two original side surfaces can also be performed in the same step as cutting the original surface. This allows for better control over the shape of the preform's side surfaces.

[0020] The present invention also relates to a method for manufacturing blades formed of composite materials, the method comprising the following steps: - Fabricate fiber preforms for reinforcing elements as described above. - A fiber preform for manufacturing blades, the preform comprising at least two skins connected to each other at one end and defining a cavity therebetween leading to an opening. - Insert all or part of the fiber preform of the reinforcing element into the cavity of the fiber blank of the blade to fill the opening of the cavity. - Densification of the fiber preform formed by the fiber preform containing reinforcing elements in the blade fiber preform is achieved by densifying the matrix to obtain a blade made of composite material including reinforcing elements.

[0021] According to a particular embodiment of the invention, a filling element is inserted into the base of the cavity of the fiber preform of the blade before the fiber preform of the reinforcing element is inserted into the cavity.

[0022] The density of the filler element is preferably lower than that of the reinforcing element and the blade preform, which allows for a reduction in the final blade mass.

[0023] According to a specific embodiment of the present invention, the blade is a stator blade. The blade may also be a rotor blade or a propeller blade.

[0024] In fact, this blade configuration is particularly suitable for fixing blades.

[0025] The present invention also relates to a blade obtained by the above manufacturing method, wherein the thickness of the blade reinforcement element is increased by at least 200% at a distance less than 50% of the height of the reinforcement element.

[0026] Finally, the present invention relates to a turbine engine comprising at least one blade as described above. Attached Figure Description

[0027] Figure 1 This is a partial schematic 3D diagram of a fiber web formed through three-dimensional weaving.

[0028] Figure 2 It is a schematic three-dimensional view of the fiber blank of the reinforcing element.

[0029] Figure 3 This is a schematic 3D diagram of a pre-compaction tool.

[0030] Figure 4 yes Figure 2 A schematic cross-sectional view of the fiber preform, arranged in Figure 3 In the pre-compaction tools.

[0031] Figure 5 yes Figure 2 A schematic top view of the fiber preform, arranged in Figure 3 In the pre-compaction tools.

[0032] Figure 6 yes Figure 2 The fiber preforms are obtained through Figure 3 A schematic 3D diagram of tools being pre-compacted.

[0033] Figure 7 It is a schematic top view of a fiber blank arranged in a precompaction tool according to a variation of the present invention.

[0034] Figure 8 yes Figure 7 A schematic three-dimensional view of a pre-compacted fiber preform.

[0035] Figure 9 yes Figure 6 An exploded view of the arrangement of the pre-compacted fiber blank in the compaction tool.

[0036] Figure 10 This is a schematic cross-sectional view of the fiber preform for reinforcing elements inserted into the fiber preform of the blade. Detailed Implementation

[0037] This invention is generally applicable to the production of turbine engine blades or guide vanes made of composite materials, including reinforcing elements.

[0038] This invention provides an advantageous application for stator blades (also known as fixed blades, such as rectifier blades). Blades obtained by the method of this invention can be OGV type distributor blades, used as "outlet guide vanes" in ducted engines. Blades obtained by the method of this invention can also be stator blades for non-ducted engines. Therefore, blades obtained by the method of this invention can be blades for UDF type turboprop engines (comprising two non-ducted and counter-rotating fans) or USF type turboprop engines (comprising one non-ducted fan and one rectifier).

[0039] The manufacturing method according to the invention includes producing a fiber preform for a reinforcing element. The fiber preform for the reinforcing element is used for molding to obtain a fiber preform for the reinforcing element. The fiber preform for the reinforcing element is used to form a fiber reinforcement for the reinforcing element.

[0040] According to a specific embodiment of the present invention, the fiber preform is obtained by trimming / trimming the fiber strip. The trimming / trimming of the fiber preform in the fiber strip can be performed by waterjet cutting.

[0041] Figure 1 An example of a fiber strip 1000 is shown, which allows for the preparation of a fiber blank 100 for reinforcing elements.

[0042] The fiber web 1000 is made by three-dimensional weaving between multiple warp yarns and multiple weft yarns. The fiber web 1000 can be produced using a Jacquard loom in a well-known manner. "Three-dimensional weaving" here refers to a weaving method used to combine at least a portion of the warp yarns with the weft yarns on multiple weft layers. To improve its surface condition, the fiber web or fiber blank made by three-dimensional weaving can incorporate another weaving method, such as two-dimensional weaving, on its surface. The fiber web or fiber blank can, for example, have interlocking or multi-satin type three-dimensional weave patterns. Different available three-dimensional weaving methods are described in document WO2006 / 136755.

[0043] The warp yarns of the fiber tape 1000 generally extend along a first direction D1, while the weft yarns of the fiber tape 1000 generally extend along a second direction D2 perpendicular to the first direction D1. Therefore, the fiber tape 1000 extends longitudinally along the first direction D1 and laterally along the second direction D2. The thickness of the fiber tape 1000 extends along a third direction D3 perpendicular to the first direction D1 and the second direction D2.

[0044] The fiber preform 100 inside the fiber tape 1000 can be cut using a well-known method: waterjet cutting. The fiber preform 100 is cut out in the fiber tape 1000 along a predetermined cutting path T. Preferably, to facilitate cutting the fiber tape 1000, the path T is rectangular, such as... Figure 1 As shown. To achieve a favorable orientation of the fibers in the fiber preform 1000 of the reinforcing element, the path T can consist of straight lines T1, T2, T3, and T4 oriented along a first direction D1 or a second direction D2 (i.e., oriented along the warp and weft directions). Figure 1 In the example shown, the longitudinal lines T2 and T4 of path T extend along the first direction D1, and the transverse lines T1 and T3 of path T extend along the second direction D2.

[0045] Multiple reinforcing element fiber blanks can be cut from the same fiber strip.

[0046] Figure 2 The fiber preform 100 thus cut is schematically shown. The fiber preform 100 extends along a first direction D1 between a reference surface 101 and the original surface 103. Figure 1 and 2 In the example shown, reference surface 101 is obtained by cutting fiber strip 1000 along a transverse straight line T1 of path T, while original surface 103 is obtained by cutting fiber strip 1000 along a transverse straight line T3 of path T. Fiber blank 100 extends along a second direction D2 between a first side surface 102 and a second side surface 104. Figure 1 and 2 In the example shown, the first side surface 102 is obtained by cutting the fiber strip 1000 along the longitudinal straight line T2 of the path T, while the second side surface 104 is obtained by cutting the fiber strip 1000 along the longitudinal straight line T4 of the path T. The fiber preform 100 extends along a third direction D3 between the first surface to be formed 105 and the second surface to be formed 106. The surfaces to be formed 105 and 106 of the fiber preform 100 are preferably flat to facilitate manufacturing; that is, they extend in a plane along the first direction D1 and the second direction D2.

[0047] Therefore, the preform is produced by three-dimensional weaving of multiple warp yarns 1001 and multiple weft yarns 1002. The fiber preform 100 can contain various types of yarns or monofilaments, particularly ceramic yarns, carbon fibers, or mixtures of such yarns. Preferably, the fiber preform can be made of silicon carbide fibers. Generally, the fiber preform can also be made of fibers made of the following materials: alumina, mullite, silica, aluminosilicates, borosilicates, carbon, or mixtures of several of these materials.

[0048] For ease of production, the fiber preform 100 is preferably produced in a manner that does not expose the warp yarn 1001 layer. That is, all the warp yarns 1001 of the fiber preform 100 extend from the reference surface 101 to the original / unprocessed surface 103, and the warp yarns do not pass through the surfaces to be formed 105 and 106 and are exposed.

[0049] The fiber preform 100 includes a first portion 110 extending from a reference surface 101 along a first direction D1 and extending along the entire length of the fiber preform 100 between two side surfaces 102 and 104. Therefore, the first portion 110 includes the reference surface 101 and a portion of the two side surfaces 102 and 104. The first portion 110 does not include the original surface 103. The fiber preform 100 also includes a second portion 120 extending from the original surface 103 along the first direction D1 and extending along the entire length of the fiber preform 100 between the two side surfaces 102 and 104. Therefore, the second portion 120 includes the original surface 103 and a portion of the two side surfaces 102 and 104. The second portion 120 does not include the reference surface 101.

[0050] Preferably, the compaction capacity of the first portion 110 of the fiber preform 100 is greater than that of the second portion 120 of the fiber preform 100. The expansion rate of the first portion 110 can be greater than that of the second portion 120. The difference in compaction capacity between the first portion 110 and the second portion 120 can be achieved in various ways known to those skilled in the art. For example, the compaction capacity can be varied by using weft yarns of different diameters. Therefore, the average diameter of the weft yarns in the first portion 110 of the fiber preform 100 can be smaller than the average diameter of the weft yarns in the second portion 120. Preferably, in order to form the specific shape required for the reinforcing element, the average diameter of the weft yarns of the fiber preform 100 gradually increases along a first direction D1 from the reference surface 101 toward the original surface 103. Each row of weft yarns in the fiber preform 100 can have the same number of weft yarns, and each row of weft yarns extends along a third direction D3.

[0051] The fiber preform 100 can be formed from multiple first weft yarns 1002a having a first diameter and multiple second weft yarns 1002b having a second diameter, wherein the second diameter is larger than the first diameter. Therefore, the first portion 110 of the fiber preform 100 may consist only of first weft yarns 1002a, while the second portion 120 of the fiber preform 100 may include second weft yarns 1002b. In this configuration, if it is desired to gradually increase the average diameter of the weft yarns along the first direction D1 from the reference surface 101 to the original surface 103, the proportion of second weft yarns 1002b in each row of weft yarns can be gradually increased. Of course, it is also not beyond the scope of the invention to form the fiber preform from two or more weft yarns of different diameters.

[0052] Then, the fiber preform 100 is placed in the pre-compacting tool 5. Figure 3 An example of this precompaction tool is shown.

[0053] The pre-compacting tool 5 includes a first clamp 51 and a second clamp 52 arranged opposite to each other. Specifically, the first clamp 51 includes a contact surface 51a arranged opposite to the contact surface 52a of the second clamp 52. The clamps 51 and 52 may be made of metal such as steel. The clamps 51 and 52 are generally along a first direction D. 51 and perpendicular to the first direction D 51 Second direction D 52 Further, the contact surfaces 51a and 52a of the two clamps 51 and 52 can have the same geometry, that is, they are symmetrical. Alternatively, the contact surfaces 51a and 52a of the two clamps 51 and 52 can have different geometries.

[0054] The precompaction tool 5 also includes a base 53. The base 53 is positioned along the second direction D. 52 and perpendicular to the first direction D 51 Second direction D 52 Third party to D 53 Extension. Two clamps 51 and 52 extend from the base 53 along the first direction D. 51 extend.

[0055] Clamps 51 and 52 along the third direction D 53 They are spaced apart from each other. The two clamps 51 and 52 are positioned along the third direction D. 53 The spacing is adjustable. Therefore, the two clamps 51 and 52 can move along the third direction D. 53 They translate relative to each other. The volume defined by the base 53 and the clamps 51 and 52 defines the pre-compacted receiving cavity.

[0056] The fiber preform 100 can be arranged in the precompacting tool 5, such that the first, second, and third directions D1, D2, and D3 of the fiber preform 100 are respectively aligned with the first, second, and third directions D of the precompacting tool 5. 51 D 52 and D 53 Overlap, such as Figure 4 and 5 As shown in the example.

[0057] A fiber preform 100 is arranged in a precompacting tool 5 such that a reference surface 101 of the fiber preform 100 contacts the base 53 of the precompacting tool 5. Therefore, the reference surface 101 is located between the two clamps 51 and 52 of the precompacting tool 5. However, when the fiber preform 100 is arranged in the precompacting tool 5, the reference surface 101 may have one or more protrusions extending from the clamps 51 and 52 along a second direction D2, D... 52 Prominent parts, such as Figure 5 As shown in the example. When the fiber blank 100 is arranged in the precompacting tool 5, the reference surface 101 can also be located entirely between the two clamps 51 and 52.

[0058] Adjust the spacing between clamps 51 and 52 so that clamps 51 and 52 contact the surfaces 105 and 106 to be formed. When the fiber preform 100 is arranged in the pre-compacting tool 5, the original surface 103 is in a free state, that is, it is not located between clamps 51 and 52. When the fiber preform 100 is arranged in the pre-compacting tool 5, the side surfaces 102 and 104 each have at least one [missing information - likely a direction or feature] extending from clamps 51 and 52 along the first direction D1, D2. 51 Prominent parts, such as Figure 4 and 5 As shown. When the fiber preform 100 is arranged in the precompacting tool 5, the side surfaces 102 and 104 of the fiber preform 100 can be located between clamps 51 and 52. When the fiber preform 100 is arranged in the precompacting tool 5, the side surfaces 102 and 104 may each have at least one [missing information - likely a direction or feature] extending from clamps 51 and 52 along a second direction D2, D4. 52 Prominent parts, such as Figure 5 As shown. In this configuration, at least one of the side surfaces 102 or 104 can be in a free state. When the fiber blank 100 is arranged in the precompacting tool 5, both side surfaces 102 and 104 can be in a free state. In this configuration, side surfaces 102 and 104 are referred to as the original side surfaces.

[0059] The spacing between clamps 51 and 52 is adjusted such that clamps 51 and 52 compress the fiber preform 100 to obtain a pre-compacted preform 100'. Thus, the spacing between clamps 51 and 52 is adjusted such that the pre-compacted accommodating cavity defined between the base 53 and clamps 51 and 52 has the shape of the reinforcing element to be obtained. Compression of the fiber preform 100 can be achieved, in particular, by varying the compaction capacity of the fiber preform 100 along the first direction D1. Therefore, the thickness reduction of the first portion 110 of the fiber preform 100 along the third direction D3 is greater than the thickness reduction of the second portion 120 of the fiber preform 100 along the third direction D3.

[0060] Preferably, the geometry and spacing of clamps 51 and 52 are configured to form a pre-compacted fiber blank 100' with an outwardly expanding (flared) shape.

[0061] The pressure applied to the fiber preform 100 by clamps 51 and 52 allows for shaping of the surfaces 105 and 106 to be formed, thereby obtaining pre-compacted fiber preform 100' with the desired forming surfaces 105' and 106'. The pressure applied to the fiber preform 100 by clamps 51 and 52 allows for reduction of the area of ​​the reference surface 101, thereby obtaining pre-compacted reference surface 101' of the pre-compacted fiber preform 100' with the desired pre-compacted surface 101'. The pressure applied to the fiber preform 100 by clamps 51 and 52 allows for shaping of the side surfaces 102 and 104, thereby obtaining pre-compacted side surfaces 102' and 104' of the pre-compacted fiber preform 100' with the desired pre-compacted surface 102' and 104'.

[0062] Then, the pre-compacted blank 100' is cut while still being pre-compacted in the pre-compacting tool 5. The pre-compacted blank 100' is preferably cut using waterjet cutting. The pre-compacted blank 100' is cut along the cutting path T. d Perform the cutting. The cutting path Td contains at least one part T. d3 The original surface 103 of the fiber preform 100 is removed. In fact, the original surface 103 is removed while the fiber preform is pre-compacted in the pre-compacting tool 5. Cutting the fiber preform 100 by removing the original surface 103 allows for obtaining a clean surface 103' with the desired shape.

[0063] Cutting is preferably performed along the free edges of clamps 51 and 52. The trajectory of the water jet is preferably along a third direction D3, D 53 Direction. The feed rate of the water jet can be between 150 mm / min and 250 mm / min. The water jet can flow along a second direction D2, D... 52 Follow the straight path Td3 to remove the original surface 103, as follows. Figure 5 As shown. However, if the cutting path used to remove the original surface 103 is non-linear, it does not depart from the scope of the invention. For example, the cutting path used to remove the original surface 103 may have a first direction D1, D2. 51 The extended portion. Therefore, the clean surface 103' obtained by cutting the fiber blank 100 can have a specific geometry adapted to the desired shape of the insert.

[0064] The cutting path Td may also include at least one part T d2 or T d4 This is used to remove the original side surfaces 102 or 104 of the fiber blank 100. In practice, the original side surfaces 102 or 104 can be removed when the fiber blank is pre-compacted in the pre-compacting tool 5. By removing the original side surfaces 102 and 104 to cut the fiber blank 100, clean side surfaces 102' and 104' with the desired shape can be obtained.

[0065] Cutting can be performed while the blank is pre-compacted, resulting in an outwardly expanded geometry of the pre-compacted blank with a sudden change in thickness and extremely high precision.

[0066] Then, the pre-compacted and cut fiber blank 100' is removed from the pre-compacting tool 5, as follows: Figure 6 As shown.

[0067] Figure 7 and 8 The illustration shows a variation in which a non-linear cutting path T is performed within a plane encompassing the first and second directions. dbis The original surface 203 of the pre-compacted fiber blank 200' is cut to obtain a clean surface 203' with a complex geometry. The shape of the pre-compacting tool 5', especially the shape of the clamp 51', is clearly customized to facilitate cutting.

[0068] Then, the pre-compacted and cut fiber blank 100' is placed in the compaction tool 6, such as... Figure 9 As shown. In reality, when the pre-compacted fiber blank 100' is removed from the pre-compacting tool 5, it may re-expand and not have the desired fiber volume ratio.

[0069] The compaction tool 6 preferably comprises a plurality of blocks 60 configured to compact and cut the fiber preform 100'. The compaction tool 6 is configured to compact the pre-compacted fiber preform 100' to a desired fiber volume ratio. The compaction tool 6 is configured to compact the pre-compacted fiber preform 100' to obtain a fiber volume ratio between 50% and 70%. The compaction tool 6 is configured to compact the pre-compacted fiber preform 100' into a fiber preform 10 for reinforcing elements. The fiber preform 10 for reinforcing elements is used to form fiber reinforcements for reinforcing elements, which will be densified by the matrix.

[0070] The compaction tool 6 can also perform a drying function. Therefore, the fiber preform 10 located in the compaction tool 10 can undergo one or more drying cycles. Thus, the steps of compacting the pre-compacted fiber blank 100' into the fiber preform 10 and the drying step can be performed simultaneously. The fiber preform 10 placed in the compaction tool is then cooled and cold-demolded. Therefore, even in the thinnest portion, the fiber preform 10 can solidify and maintain rigidity. The resulting fiber preform 10 can have an outwardly expanding shape with abrupt changes in thickness.

[0071] Therefore, the fiber preform 10 includes a smaller first end face 11 corresponding to the reference surface 101' of the pre-compacted fiber preform 100'; and a larger second end face 13 opposite to the first end face 11, corresponding to the clean surface 103' of the pre-compacted fiber preform 100'. The fiber preform 10 also includes two forming surfaces 15 and 16, corresponding to the forming surfaces 105' and 106' of the pre-compacted fiber preform 100'.

[0072] The fiber preform 10 of the reinforcing element is intended to be densified together with at least one fiber preform of the blade to obtain a blade made of composite material.

[0073] For this purpose, the fiber preform of blade 20 is manufactured by weaving in a well-known manner, comprising at least two skins 21 and 22 connected to each other at least at one end, for example, by means of unhooking during the weaving process. A cavity leading to an opening is defined between the two skins 21 and 22 of blade preform 20. The fiber preform of blade 20 can be manufactured entirely by three-dimensional weaving. The free ends of skins 21 and 22 of blade preform 20 can be used to form one or more platforms for forming the blade to be manufactured. Preferably, the first skin 21 is located on the pressure side of the final blade, and the second skin 22 is located on the suction side of the final blade.

[0074] like Figure 10 As shown, at least a portion of the fiber preform of the reinforcing element 10 is inserted into the cavity of the fiber preform of the blade 20, such that the fiber preform of the reinforcing element 10 fills the opening of the cavity. Specifically, the first end face 11 of the fiber preform 10 is located within the cavity, while the second end face 13 is located at the opening of the cavity of the blade preform 20.

[0075] The fiber preform of the reinforcing element 10 can be fully inserted into the cavity of the blade preform 20. The fiber preform of the reinforcing element 10 may include a portion located outside the cavity of the blade preform 20.

[0076] According to a specific embodiment of the invention, at least one filler element 30 is inserted into the base of the fiber preform cavity of the blade 20 before the fiber preform of the reinforcing element 10 is inserted. In this configuration, the first end face 11 of the fiber preform 10 can contact the filler element 30. The density of the filler element is lower than that of the fiber preforms 10, 20, and 30. The filler element 30 can be made of foam, such as organic foam (polyethylacrylamide, polyethylene terephthalate (PET), polyvinyl chloride (PVC), polyetherimide (PEI), polyethylene, carbon fiber, polyisocyanurate, polyurethane, etc.). The filler element 30 can have a honeycomb structure.

[0077] According to a specific embodiment of the present invention, compatible with the foregoing embodiments, the fiberboard preform 40 can be arranged to contact the second end face 13 of the reinforcing element 10 preform and to contact the two skins 21 and 22 of the blade preform, as shown. Figure 10 As shown.

[0078] This results in a combination of fiber preforms, including a preform of reinforcing element 10, a blade preform 20, and possibly a filler element 30.

[0079] The height of the fiber preform of reinforcing element 10 can be 3% greater than the total height of the preform assembly. Specifically, the height of the fiber preform of reinforcing element 10 can be 5% greater than the total height of the preform assembly, for example, 10% greater. "The height of the fiber preform of the reinforcing element" refers to the distance between the portion of the second end face 13 furthest from the first end face 11 and the first end face 11. The height of the fiber preform of reinforcing element 10 can be less than 50% of the total height of the preform assembly. Specifically, the height of the fiber preform of reinforcing element 10 can be less than 10% of the total height of the preform assembly. The height of the fiber preform of reinforcing element 10 can be between 5% and 15% of the total height of the preform assembly. Therefore, the fiber reinforcement will extend into the final blade a sufficient distance to increase root stiffness, but will not extend excessively to limit the mass of the resulting blade.

[0080] Then, the fiber pre-assembly formed from at least the fiber preforms of the reinforcing element 10 and the fiber preforms of the blade 20 is densified. The fiber preform assembly can be placed in an injection mold whose cavity size is substantially the same as the size of the final blade to be produced.

[0081] Well-known injection molding or transfer molding, or "RTM" (resin transfer molding), can be used. According to this method, resin (e.g., thermosetting resin) is injected into the mold cavity containing the preform assembly via one or more injection ports. The resin used can be, for example, an epoxy resin with a temperature rating of 180°C. Resins suitable for RTM are well-known. They preferably have a low viscosity to facilitate injection into fibers. The choice of the resin's temperature rating and / or chemical properties depends on the thermomechanical stress the blade must withstand. Once the resin is injected into the entire preform assembly, it is heat-treated according to the RTM method to polymerize. After injection and polymerization, the blade is demolded. The blade can be selectively subjected to post-curing cycles to improve its thermomechanical properties, such as increasing its glass transition temperature. Finally, the blade is trimmed to remove excess resin. Passages and countersunk holes can be machined, particularly at the blade root.

[0082] Optionally, a leading edge can be inserted. The outer layer constituting the leading edge is then applied to the component to achieve mating of the leading edge. The leading edge is then heat-pressed to bond it to the component.

[0083] This results in a blade made of a composite material, comprising reinforcing elements made of the composite material, the fiber reinforcements of which are formed from fiber preforms of the reinforcing elements 10. The resulting blade is preferably made of an organic matrix composite material. In fact, organic matrix composite materials have good mechanical properties and are lightweight. Of course, it is not beyond the scope of the invention if the blade is densified in a well-known manner using a ceramic matrix (e.g., by means of grouting).

Claims

1. A method for manufacturing a fiber preform (10) for a blade reinforcement element, comprising the following steps: 1) A fiber preform (100) is formed by three-dimensionally weaving multiple warp yarns (1001) extending along a first direction (D1) and multiple weft yarns (1002) extending along a second direction (D2) intersecting the first direction (D1), the fiber preform (100) extending along the first direction (D1) between a reference surface (101) and a primary surface (103), and extending along a third direction (D3) intersecting the first direction (D1) and the second direction (D2) between two surfaces to be formed (105, 106). - The original surface (103) of the fiber blank (100) is removed by water jet cutting to form a clean surface (103'). - The fiber preform (100') including a clean surface (103') is arranged in a compaction tool (6) to obtain a fiber preform (10) having the shape of the reinforcing element to be obtained and having a defined volume fiber content. The method is characterized by further including: Before removing the original surface (103) of the fiber preform (100), the fiber preform (100) is arranged in a precompacting tool (5), the precompacting tool (5) comprising a receiving cavity defined by a base (53) and two clamps (51, 52) extending from the base (53), the spacing between the two clamps (51, 52) being adjustable, the fiber preform (100) being arranged in the receiving cavity of the precompacting tool (5) such that the reference surface (101) of the fiber preform (100) contacts the base (53), and then... - Adjust the clamps (51, 52) of the precompacting tool (5) so that the accommodating cavity of the precompacting tool (5) has the shape of the fiber preform (10) of the reinforcing element to be obtained, so as to precompact the fiber preform (100), the surfaces (105, 106) of the fiber preform (100) to be formed are arranged to contact the clamps (51, 52), and the original surface (103) of the fiber preform (100) is in a free state. While the fiber blank (100) is pre-compacted in the pre-compacting tool (5), the step of removing the original surface (103) is performed. After the step of removing the original surface (103), the pre-compacted fiber blank (100') is taken out from the pre-compacting tool (5) and then placed into the compaction tool (6).

2. The method according to claim 1, wherein, The fiber blank (100) is obtained by water jet cutting of the fiber strip (1000) produced by three-dimensional weaving at the loom exit.

3. The method according to claim 1 or 2, wherein, The reference surface (101) and the original surface (103) of the fiber blank (100) include the same number of warp yarns (1001).

4. The method according to claim 1, wherein, The fiber preform (100) includes a first portion (110) extending from the reference surface (101) with a compaction capacity greater than that of a second portion (120) extending from the original surface (103) of the fiber preform.

5. The method according to claim 4, wherein, The average diameter of the weft yarns (1002a, 1002b) of the second part (120) of the fiber preform (100) is greater than the average diameter of the weft yarns (1002a) of the first part (110) of the fiber preform (100).

6. The method according to claim 1, wherein, The water jet cut used to remove the original surface (103) follows a non-linear profile.

7. The method according to claim 1, wherein, The fiber blank (100) is arranged in the pre-compacting tool (5) such that the two original side surfaces (102, 104) of the fiber blank (100) opposite each other in the second direction (D2) are free. When the fiber blank (100) is pre-compacted in the pre-compacting tool (5), the two original side surfaces (102, 104) are removed by water jet cutting.

8. A method for manufacturing a blade made of a composite material, the method comprising the following steps: - A fiber preform (10) for manufacturing reinforcing elements by the method according to any one of claims 1 to 7. - A fiber preform (20) for manufacturing the blade, the fiber preform comprising at least two skins (21, 22) connected to each other at one end and defining a cavity between them leading to an opening. - Insert all or part of the fiber preform (10) of the reinforcing element into the cavity of the fiber preform (20) of the blade to fill the opening of the cavity. - The assembly formed by densifying the fiber preform (10) of the fiber preform (20) arranged in the blade by the matrix is ​​obtained to obtain a blade made of composite material including the reinforcing element.

9. The method according to claim 8, wherein, Before inserting the fiber preform (10) of the reinforcing element into the cavity, the filling element (30) is inserted into the cavity base of the fiber preform (20) of the blade.

10. The method according to claim 8 or 9, wherein, The blades are stator blades, rotor blades, or propeller blades.

11. A blade obtained by the method according to any one of claims 8 to 10, wherein the thickness of the reinforcing element of the obtained blade is increased by at least 200% over a distance less than 50% of the height of the reinforcing element.

12. A turbine engine comprising at least one blade according to claim 11.

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