Reproducible forming of fiber blanks

Abstract

The invention relates to a forming method of a fibrous blank (200) comprising a warp thread tracer (101a) and at least one weft thread tracer (102a, 102b, 102c), the method comprising: - projecting a warp thread visual mark (501a) corresponding to a reference position of the warp thread tracer (101a) on the fibrous blank (200); - deforming the blank (200) from a bottom of the airfoil blank to a top of the airfoil blank so that the warp thread tracer (101a) corresponds to its visual mark (501a); - projecting weft thread visual marks (502a, 502b, 502c) corresponding to reference positions of the weft thread tracers (102a, 102b, 102c) on the fibrous blank (200); - deforming the blank (200) from the warp thread tracer (101a) to a first edge (205a) and to a second edge (205b) of the blank (200) so that the weft thread tracers (102a, 102b, 102c) correspond to their visual marks (502a, 502b, 502c).

Description

Technical Field

[0001] The present invention relates to the manufacture of blades or propellers made of composite materials comprising fiber reinforcements formed by three-dimensional weaving and densified by a matrix. Background Technology

[0002] Using composite materials to manufacture blades or propellers (such as gas turbine blades for aircraft engines or industrial turbines) makes it possible to obtain components with mechanical properties equal to or even better than those made of metal, while having a much lower weight.

[0003] The manufacture of these blades or propellers can begin with the production of a single fiber preform through three-dimensional weaving, which is then shaped to obtain a fiber preform for the blade or propeller to be manufactured. The fiber preform is then densified with a matrix to obtain the component. Examples of methods for manufacturing blades or propellers made of composite materials are described, for example, in documents FR3046564 or FR304653.

[0004] The fiber preform comprises two types of yarns that form the web: warp yarns (extending along the weaving direction) and weft yarns (extending transversely to the weaving direction). The warp yarns are substantially parallel to each other, and the weft yarns are substantially parallel to each other. The warp and weft yarns generally intersect at approximately right angles, thus forming a roughly orthogonal warp / weft web structure.

[0005] However, the shape of the blades or propellers to be manufactured is not developable. Therefore, when the fiber preform is deformed to obtain a fiber preform, a loss of orthogonality in the warp and weft mesh structure can be observed locally. This loss of orthogonality is called decadation. The angle at which the decadation position of the weft thread is measured from its original position is called the "decadation angle".

[0006] However, the larger the offset angle, the more the mechanical properties of the resulting fiber preform will be altered. During traction and compression, the offset material becomes more flexible in the weft direction and more rigid in the warp direction. Therefore, a considerable offset will result in a relatively large loss of mechanical properties in the weft direction. Consequently, it will be necessary to manufacture thicker fiber preforms than without offset, which requires a non-negligible weight increase for the performance of turbines or engines.

[0007] The step of deforming a fiber preform into a fiber preform can be performed using visual references, allowing control over the arrangement of certain weft or warp threads. This method is described, for example, in US2016288380A1. However, this step of deforming the fiber preform into a fiber preform is performed manually without any ordered forming sequence, which introduces significant variability between parts and in the location of offset areas. Ultimately, the mechanical properties of the parts differ considerably, and the parts obtained after the resin injection preform step have different geometries. Summary of the Invention

[0008] The purpose of this invention is to overcome the above-mentioned deficiencies by proposing a series of forming processes for predetermined fiber preforms, thereby allowing for adaptive and reproducible deformation of the preforms.

[0009] Therefore, the present invention proposes a method for forming a fiber preform, wherein the fiber preform extends longitudinally along direction X and laterally along direction Y, is obtained by three-dimensional weaving between multiple warp and weft yarns, and is used to form a fiber preform for turbine blades. The fiber preform includes a root preform for forming the blade root and an airfoil preform for forming the blade airfoil. The fiber preform includes a reference plane extending along direction Y between a first edge for forming the leading edge of the blade and a second edge for forming the trailing edge of the blade. The fiber preform also includes warp tracer lines extending along direction X from the root preform on the reference plane and at least one weft tracer line extending along direction Y on the reference plane between the first and second edges. The method includes at least:

[0010] - Place the fiber blank in the forming mold so that the reference surface is visible;

[0011] - Keep the root blank in the forming mold;

[0012] - Project at least one warp visual reference onto the reference position corresponding to the warp tracer on the reference surface of the fiber blank;

[0013] -Deform the airfoil blank in direction X from the bottom to the top of the airfoil blank so that the warp tracer line corresponds to the warp visual reference.

[0014] - Project at least one weft visual reference onto the reference position corresponding to the weft tracer line on the reference surface of the fiber blank;

[0015] - The airfoil blank is deformed in the Y direction from the warp tracer line to the first and second edges of the blank, so that the weft tracer line corresponds to the weft visual reference.

[0016] Therefore, the forming method is predetermined and identical between each operator. The deformation from bottom to top and from center to edge, in particular, enables identical positioning of the offset areas between parts, and thus better prediction of areas with weak mechanical properties in the weft direction.

[0017] According to one specific aspect of the invention, the fiber preform includes a plurality of weft yarn tracer lines distributed between the bottom and top of the airfoil preform, wherein a plurality of weft yarn visual references corresponding to the reference positions of the weft yarn tracer lines are projected, and the following steps are repeated for each weft yarn tracer line in order from the bottom to the top of the airfoil preform:

[0018] -Deform the airfoil blank in the Y direction from the warp tracer line to the first and second edges of the blank, so that the weft tracer line corresponds to the corresponding weft visual reference, and so that all weft tracer lines correspond to the corresponding weft visual reference.

[0019] According to another specific aspect of the invention, the deformation of the airfoil blank in the Y direction is performed as follows: from the warp tracer to the first edge of the blank such that the weft tracer corresponds to a portion of the weft visual reference, and then from the warp tracer to the second edge of the blank such that the weft tracer corresponds to the corresponding weft visual reference.

[0020] According to another specific aspect of the invention, the projection of the visual reference is performed by laser.

[0021] According to another specific aspect of the invention, the visual reference corresponding to the tracer line includes a line having the same width as the tracer line.

[0022] According to another specific aspect of the invention, the visual reference corresponding to the tracer line includes two lines defining a region corresponding to the reference position of the tracer line.

[0023] According to another specific aspect of the invention, the fiber preform is wetted before deformation to facilitate its deformation.

[0024] The present invention also relates to a method for manufacturing turbine blades made of composite materials, comprising:

[0025] - A fiber blank is produced by three-dimensional weaving of a thread, the fiber blank including a root blank for forming the root of a blade and an airfoil blank for forming the airfoil of a blade, the fiber blank including a reference plane extending between a first edge for forming the leading edge of the blade and a second edge for forming the trailing edge of the blade, the thread including at least a warp tracking thread and at least one weft tracking thread disposed on the reference.

[0026] - While keeping the tracer lines on the reference plane intact, cut out the fiber blank to obtain a trimmed fiber blank that can represent the shape and size of the blade components;

[0027] - The fiber blank is shaped according to the forming method of the present invention to obtain a shaped fiber preform;

[0028] - Inject matrix precursor resin into fiber preforms to impregnate the fiber preforms;

[0029] - The matrix precursor resin in the fiber preform is converted into a matrix to obtain a composite component comprising fiber reinforcements that are densified by the matrix and have the shape and size of blades. Attached Figure Description

[0030] [ Figure 1 ] Figure 1 This is a schematic three-dimensional diagram of a fiber preform used to produce fiber preforms through three-dimensional weaving.

[0031] [ Figure 2 ] Figure 2 It is cutting Figure 1 A schematic three-dimensional view of the fiber preform obtained after the fiber preform is fabricated.

[0032] [ Figure 3 ] Figure 3 Yes Figure 2 A schematic diagram of the blade obtained after forming and densifying the fiber preform.

[0033] [ Figure 4 ] Figure 4 This is a schematic perspective view of a forming mold and a laser projector according to one embodiment of the present invention.

[0034] [ Figure 5 ] Figure 5 yes Figure 2 The fiber preform was placed in a non-deformed state. Figure 4 A schematic three-dimensional view of the forming mold.

[0035] [ Figure 6 ] Figure 6 yes Figure 5 The fiber blank is deformed into a schematic three-dimensional diagram in which the warp tracer lines are aligned with their visual reference.

[0036] [ Figure 7 ] Figure 7 yes Figure 6 The fiber blank is deformed into a schematic three-dimensional diagram in which the first weft yarn tracer line is consistent with its visual reference.

[0037] [ Figure 8 ] Figure 8yes Figure 7 The fiber blank is deformed into a schematic three-dimensional diagram in which the second weft yarn tracer line is consistent with its visual reference.

[0038] [ Figure 9 ] Figure 9 yes Figure 8 The fiber preform is deformed into a schematic stereoscopic view in which all tracer lines are aligned with their visual reference. Detailed Implementation

[0039] This invention is generally applied to the production of turbine blades or propellers made of composite materials, the blades comprising fiber reinforcements densified by a matrix. Embodiments for composite blades will be described below. Of course, this does not depart from the scope of the invention when the produced composite component is a propeller.

[0040] Methods for manufacturing composite blades begin with the production of fiber preforms obtained through three-dimensional or multi-layer weaving.

[0041] It is understood that the term "three-dimensional weaving" or "3D weaving" refers to a weaving method in which at least some warp yarns are linked to weft yarns on several weft layers, such as, for example, "interlocking weaving." It is understood that the term "interlocking weaving" refers to a type of 3D weaving in which each warp layer is linked to several weft layers, and all yarns on the same warp bob have the same movement within the weaving plane. It should generally be noted that the roles of warp and weft yarns are interchangeable.

[0042] Understandably, the term “multilayer fabric” here refers to a three-dimensional fabric with several weft layers, where the basic fabric of each layer is equivalent to a traditional 2D woven fabric, such as canvas, satin, or serge, but the weft layers are connected to each other at certain points in the fabric.

[0043] Producing fiber preforms through 3D weaving allows for bonding between layers in a single textile operation, thereby giving the fiber preforms and thus the composite blades good mechanical resistance.

[0044] An exemplary embodiment of the fiber preform will now be described. In this example, the fabric is produced on a jacquard loom.

[0045] Figure 1 The diagram schematically illustrates the weaving of a fiber preform 100 from which a fiber preform 200 can be extracted. Figure 2 ), used to obtain fiber-reinforced preforms for aero-engine blades or propellers after molding.

[0046] The fiber preform 100 is obtained by three-dimensional weaving, 3D weaving, or multi-layer weaving using a jacquard loom in a known manner. In this process, a bundle of warp or ply yarns 101 is arranged in multiple layers on the jacquard loom, and these warp yarns are connected by weft yarns 102, which are also arranged in multiple layers. In this way, a substantially orthogonal warp and weft mesh structure is obtained. Detailed examples of producing fiber preforms for forming fiber reinforcements for aero-engine blades from 3D-woven fiber preforms are described in detail in documents US7101154, US7241112, and WO2010 / 061140.

[0047] The fiber preform 100 is woven in the form of a strip that generally extends in direction X, corresponding to the longitudinal direction of the blade to be produced. The fiber preform 100 extends laterally in direction Y, and its thickness extends in direction Z, which is perpendicular to directions X and Y.

[0048] In the fiber preform 100, the fiber preform 200 has a variable thickness determined according to the profile and longitudinal thickness of the airfoil portion of the blade to be produced. In the portion of the fiber preform 200 used to form the root preform, the fiber preform 200 has an extra-thick portion 203 determined according to the thickness of the root portion of the blade to be produced. The fiber preform 200 is extended to form a thickness-reducing portion 204 for forming the web of the blade, and then to a portion 205 for forming the shank of the blade. The portion 205 has a profile with a variable thickness between its edge 205a and its edge 205b along the Y direction, wherein edge 205a forms the leading edge of the blade to be produced, and edge 205b forms the trailing edge of the blade to be produced. The portion 205 extends along the Z direction between a first surface 205c and a second surface 205d, wherein the first surface 205c forms the pressure surface of the blade profile, and the second surface 205d forms the suction surface of the blade profile.

[0049] The fiber preform 200 is woven into a single component. In sections of the fiber preform with varying thicknesses, such as the thickness-reducing section 204, the reduction in preform thickness can be achieved by gradually removing weft layers during the weaving process. Once the preform 200 is woven within the preform 100, the unwoven yarns are cut off. Then, a component is obtained as shown... Figure 2 The blank 200 shown is woven into a single component.

[0050] like Figure 2As shown, the fiber preform 200 includes structural threads 101 and 102 for weaving the preform's structure, and visually identifiable tracer threads 101a, 102a, 102b, and 102c. The tracer threads 101a, 102a, 102b, and 102c, incorporated during the weaving process of the fiber preform 100, are substantially located on the surface of the fiber preform 200. Tracer thread 101a is a warp thread. Tracer threads 102a, 102b, and 102c are weft threads.

[0051] The tracer line 101a can be placed at a distance substantially equal to the edges 205a and 205b of the fiber preform used to form the blade or propeller to be manufactured.

[0052] Figure 3 The positions of the tracer lines are shown on the parts manufactured by forming fiber preforms and the preforms obtained thereby through the matrix.

[0053] exist Figure 2 and Figure 3 In the example shown, there is only a single warp tracer and three weft tracers. Of course, having fewer or more than three weft tracers does not depart from the scope of this invention.

[0054] According to one specific embodiment of the invention, the structural wire can be carbon fiber, and the tracer wire can be glass fiber, Kevlar fiber, or fiber made of a carbon-glass mixture. Therefore, the tracer wire appears light-colored relative to the darker portion of the blank.

[0055] Furthermore, the presence of these tracer lines facilitates the cutting of fiber preforms to obtain fiber blanks or to standardize them. For example, an example of such cutting using tracer lines is described in document US2015165571A1.

[0056] like Figure 4 and Figure 5 As shown, the fiber preform 200 is placed in the forming mold 6 without deformation. The forming mold 6 has a cavity 60 with the desired shape of the fiber preform.

[0057] The fiber preform 200 is positioned in the forming mold by placing the portion 203 of the fiber preform used to form the blade root in the cavity 60 of the mold 6 for receiving it.

[0058] According to one specific embodiment of the invention, the fiber preform 200, which is disposed in the mold without deformation, can be wetted, for example, with distilled water.

[0059] Then, for example, by means of a pre-compression jaw plate 61, the root of the fiber preform 200 is stopped or fixed in the mold 6. Stopping the root of the preform can result in pre-compacting of the root and allow a portion of the root fiber to be stopped in the desired position. By stopping the fiber preform with the root, rather than with the portion used to form the blade root, a smooth transition is achieved between the stopped and unstopped areas, so as to avoid fiber wrinkling at the boundary between the stopped and unstopped areas.

[0060] When the fiber blank is placed in the forming mold 6, the blank can be positioned in the following configuration: while keeping the root of the blank fixed, a rotation about an axis X parallel to the main direction is applied (which results in the airfoil portion of the blank being twisted about this axis), while deforming the blank.

[0061] In some cases, a sliding movable component may also be provided for the forming die to position itself against the free end of the blank root so as to provide the desired deformation of that portion of the blank when stress is subsequently applied, or to prevent certain types of deformation in that portion when deformation is applied to other portions of the blank.

[0062] Different blank marking and positioning systems can be used, especially laser projectors 5 (see Figure 4 This method projects a laser beam at the desired location of one or more tracer lines, allowing the corresponding tracer line to be easily moved to achieve a predetermined position. The laser beam can be a laser with the same width as its corresponding tracer line. Alternatively, the laser beam can be a laser with a wider projection area defining its corresponding tracer line. Or, the laser beam can be a dual-laser projection area of ​​two lines defining its corresponding tracer line.

[0063] The alignment of the tracer lines of the fiber preforms 200 with their visual references is carried out in a defined sequence in several steps.

[0064] according to Figure 6 In the first step shown, the laser projector 5 begins by indicating a visual reference 501a for at least the warp tracer lines. This visual reference 501a for the warp tracer lines corresponds to the reference position of the warp tracer lines 101a on the fiber preform formed in the forming mold. Therefore, the fiber preform 200 needs to be deformed so that the warp tracer lines 101a on its surface align with the visual reference 501a for the warp tracer lines.

[0065] The fiber preform 200 is deformed from the bottom of the airfoil preform to the top of the airfoil preform (i.e. in the direction of increasing horizontal coordinate X) so that the warp tracer line 101a of the preform 200 is consistent with the visual reference 501a of the warp tracer line.

[0066] By deforming the blank 200 from bottom to top, that is, from the root of the blank to the upper edge of the airfoil blank, the offset at the horizontal level at the root and bottom of the airfoil is limited. Specifically, as the fiber blank 200 deforms away from the stop portion, the offset becomes increasingly significant. Since the material properties are generally not very good at the root and at its connection with the airfoil, it is preferable to limit the offset at these locations to transfer it to the top of the airfoil, where the material properties are better and thus allow for better tolerance to offset. Furthermore, this deformation of the blank 200 from the bottom of the airfoil to the top of the airfoil facilitates the replication of deformation by controlling the arrangement of the offset regions.

[0067] according to Figure 7 In the second step shown, the laser projector 5 then indicates a visual reference 502a for at least the first weft yarn tracer, which starts from the bottom of the airfoil portion of the preform 200, i.e., from the first weft yarn tracer in the direction of increasing x on the horizontal coordinate. This visual reference 502a for the first weft yarn tracer corresponds to the reference position of the first weft yarn tracer 102a on the fiber preform formed in the forming die. Therefore, the fiber preform 200 needs to be deformed so that the first weft yarn tracer 102a on its surface coincides with the visual reference 502a for the first weft yarn tracer. Preferably, the laser projector 5 also indicates a visual reference 501a for the warp yarn tracer.

[0068] The fiber preform 200 is deformed from the warp tracer 101a toward the edge 205a of the fiber preform 200 for forming the leading edge of the blade (i.e., in the direction of increasing Y coordinate) so that the first weft tracer 102a of the preform 200 is superimposed on the portion of the visual reference 502a of the first weft tracer located between the warp tracer 101a and the edge 205a of the fiber preform 200 for forming the leading edge.

[0069] Next, the fiber blank 200 is deformed from the warp tracer line 101a toward the edge 205b of the fiber blank 200 used to form the trailing edge (i.e., in the direction of Y-coordinate reduction), such that the portion of the first weft tracer line 102a of the blank 200 and the visual reference 502a of the first weft tracer line located between the warp tracer line 101a and the edge 205b of the fiber blank used to form the trailing edge overlaps.

[0070] After the fiber blank 200 is deformed on both sides of the warp tracer 101a, the first weft tracer 102a is correctly superimposed on the visual reference 502a of the weft tracer over its entire length. At the end of this second step, the warp tracer 101a preferably remains superimposed on its respective visual reference 501a.

[0071] according to Figure 8In the third step shown, the laser projector 5 then indicates at least a visual reference 502b for the second weft tracer, which starts from the bottom of the airfoil portion of the preform 200, i.e., from the second weft tracer in the direction of increasing x of the horizontal coordinate. This visual reference 502b for the second weft tracer corresponds to the reference position of the second weft tracer 102b on the fiber preform formed in the forming die. Therefore, the fiber preform 200 needs to be deformed so that the second weft tracer 102b present on its surface coincides with the visual reference 502b for the second weft tracer. Preferably, the laser projector 5 also indicates a visual reference 501a for the warp tracer and a reference 502a for the second weft tracer.

[0072] The fiber preform 200 is deformed from the warp tracer line 101a toward the edge 205a of the fiber preform 200 that forms the leading edge of the blade (i.e., in the direction of increasing Y coordinate), such that the portion of the second weft tracer line 102b of the preform 200 and the visual reference 502b of the second weft tracer line located between the warp tracer line 101a and the edge 205a of the fiber preform 200 that forms the leading edge overlaps.

[0073] Next, the fiber blank 200 is deformed from the warp tracer line 101a toward the edge 205b of the fiber blank 200 for forming the trailing edge of the blade (i.e., in the direction of decreasing Y coordinate) so that the portion of the second weft tracer line 102b of the blank 200 and the visual reference 502b of the second weft tracer line located between the warp tracer line 101a and the edge 205b of the fiber blank for forming the trailing edge overlaps.

[0074] After the fiber blank 200 is deformed on both sides of the warp tracer 101a, the second weft tracer 102b is correctly superimposed on the corresponding visual reference 502b of the weft tracer over its entire length. At the end of this third step, the warp tracer 101a preferably remains superimposed on its corresponding visual reference 501a, and the first weft tracer 102a preferably remains superimposed on its visual reference 502a.

[0075] according to Figure 9In the fourth step shown, the laser projector 5 then indicates a visual reference 502c for at least the third weft tracer, starting from the bottom of the airfoil portion of the preform 200, i.e., from the second weft tracer in the direction of increasing horizontal coordinate X. This visual reference 502c for the third weft tracer corresponds to the reference position of the third weft tracer 102c on the fiber preform formed in the forming die. Therefore, the fiber preform 200 needs to be deformed so that the third weft tracer 102c present on its surface coincides with the visual reference 502c for the third weft tracer. Preferably, the laser projector 5 also indicates a visual reference 501a for the warp tracer, a reference 502a for the second weft tracer, and a reference 502b for the third weft tracer.

[0076] The fiber preform 200 is deformed from the warp tracer line 101a toward the edge 205a of the fiber preform 200 used to form the leading edge of the blade (i.e., in the direction of increasing Y coordinate), such that the portion of the third weft tracer line 102c of the preform 200 and the visual reference 502c of the third weft tracer line located between the warp tracer line 101a and the edge 205a of the fiber preform 200 used to form the leading edge overlaps.

[0077] Next, the fiber blank 200 is deformed from the warp tracer line 101a toward the trailing edge 205b of the fiber blank 200 for forming the blade (i.e., in the direction of decreasing Y coordinate), such that the portion of the third weft tracer line 102c of the blank 200 and the visual reference 502c of the third weft tracer line located between the warp tracer line 101a and the trailing edge 205b of the fiber blank are superimposed.

[0078] After the fiber blank 200 is deformed on both sides of the warp tracer 101a, the third weft tracer 102c is correctly superimposed on the corresponding visual reference 502c on the weft tracer over its entire length. At the end of this third step, the warp tracer 101a preferably remains superimposed on its corresponding visual reference 501a, the first weft tracer 102a preferably remains superimposed on its visual reference 502a, and the second weft tracer 102b preferably remains superimposed on its visual reference 502b.

[0079] exist Figures 4 to 9 The examples shown include both single warp tracers and three weft tracers. Of course, having fewer or more than three weft tracers does not depart from the scope of this invention.

[0080] For each additional weft tracer located above the preceding weft tracer in the direction of increasing horizontal coordinate, the process is performed in the same manner as in step four. The laser projector needs to display a visual reference corresponding to the additional weft tracer, preferably by displaying visual references corresponding to the warp tracer and the preceding weft tracer. The fiber blank 200 is then deformed from the warp tracer 101a toward the leading edge 205a of the fiber blank 200 for forming the blade, and then deformed from the warp tracer 101a toward the trailing edge 205b of the fiber blank 200 for forming the blade, such that the additional weft is superimposed on the corresponding visual reference along its entire length. At the end of this additional step, the warp tracer preferably remains superimposed on its corresponding visual reference, and the preceding weft tracers preferably remain superimposed on their respective visual references.

[0081] Deforming the fiber blank 200 from the warp tracer line 101a (preferably positioned toward the center of the fiber blank 200) toward the edge of the blank ensures good reproducibility of the deformation and good control over the location of the offset area (which will be mainly located on the edge of the blank).

[0082] By deforming the fiber preform 200 to align the weft tracers with their visual references from the bottom to the top of the airfoil, offset is limited at the horizontal level of the root and bottom of the airfoil. Specifically, the offset becomes increasingly significant as the fiber preform 200 gradually deforms away from the stop portion (i.e., the blade root). Since material properties are generally less favorable at the root and at its junction with the airfoil, it is preferable to limit the offset in these areas to shift it to the top of the airfoil, where material properties are better, thus allowing for better tolerance of the offset. Furthermore, this deformation of the bottom of the airfoil of the preform 200 towards the top of the airfoil facilitates the reproducibility of the deformation, and the offset areas are arranged in a controlled manner.

[0083] Of course, if the roles of the edges of the preform used to form the leading edge of the blade and the edges of the preform used to form the trailing edge are exchanged or alternated in the preceding steps, it does not depart from the scope of the invention. For each weft tracer, the deformation of the fiber preform from the warp tracer to the first edge of the preform simplifies the deformation of the fiber preform in the Y-axis direction. The operator can easily and quickly repeat this series of deformations independently while maintaining good reproducibility and the same offset area position between the blades. This series of deformations constitutes a preferred embodiment of the invention.

[0084] However, if the deformation of the fiber blank in the Y-axis direction is carried out simultaneously or alternately on either side of the warp tracer toward each edge, so that the weft tracer is superimposed on its corresponding visual reference, it does not depart from the scope of the invention. However, it is relatively difficult for a single operator to achieve this series of deformations while maintaining good reproducibility.

[0085] When the fiber preform is fully deformed, all visual references for the tracer lines—with or without tolerances—can be re-examined to verify that all tracer lines are correctly superimposed on their respective visual references. Minor deformations can be achieved to ensure that all tracer lines are satisfactorily superimposed on their respective visual references.

[0086] If the fiber preform is wetted before the deformation step, it can be dried after deformation.

[0087] Following these deformation steps, the deformed fiber preform can be compacted in a compaction die, where applicable, preceded by a pre-compaction step. These pre-compaction or compaction steps are described, for example, in documents US2016243777A1 or US2016288380A1. The compaction die may include a forming die.

[0088] Therefore, fiber preforms are obtained after the fiber blank is formed and properly compacted.

[0089] The fiber preform is then impregnated with a thermosetting resin that has been cured by heat treatment. For example, well-known injection or transfer molding, known as RTM (“Resin Transfer Molding”), can be used for this purpose. According to the RTM method, resin (e.g., a thermosetting resin) is injected into the internal space of the injection mold occupied by the preform through an injection port. This configuration allows a pressure gradient to be established between the lower portion of the preform in which resin is injected and the upper portion of the preform located near the discharge port. In this way, the resin injected essentially at the level of the lower portion of the preform will gradually impregnate the entire preform by circulating throughout the preform to the discharge port, through which the remaining resin is discharged. Of course, the injection molding tool may include several injection ports and several discharge ports.

[0090] Resins suitable for the RTM method are well known. They preferably have low viscosity to facilitate their infusion into the fibers. The choice of the resin's temperature rating and / or chemical properties is determined based on the thermomechanical stresses the component must withstand. Once the resin is infused into the entire reinforcement, it is then cured by heat treatment according to the RTM method.

[0091] After injection and curing, the blade is released from the mold. Where applicable, it can undergo post-baking cycles to improve its thermomechanical properties. Finally, the blade is trimmed to remove excess resin and may be machined with chamfers. This yields a composite component formed from fiber reinforcements densified through a matrix.

[0092] The protective layer can be bonded to the resulting composite material component.

Claims

1. A method for forming a fiber preform, the fiber preform extending longitudinally along direction X and laterally along direction Y, obtained by three-dimensional weaving between multiple warp yarns and multiple weft yarns, and used to form a fiber preform for a turbine blade, the fiber preform including a root preform for forming a blade root and an airfoil preform for forming a blade airfoil, the fiber preform including a reference plane extending along direction Y between a first edge and a second edge for forming the leading and trailing edges of the blade, the fiber preform including warp tracer lines extending from the root preform along direction X on the reference plane and at least one weft tracer line extending along direction Y on the reference plane between the first edge and the second edge, the method comprising at least: - Place the fiber preform in the forming mold so that the reference surface is visible; - Hold the root blank in the forming mold; - Project at least one warp visual reference corresponding to the reference position of the warp tracer line onto the reference surface of the fiber blank; - The airfoil blank is deformed in the direction X from the bottom to the top of the airfoil blank, so that the warp tracer line corresponds to the warp visual reference; - Project at least one weft visual reference corresponding to the reference position of the weft tracer line onto the reference surface of the fiber blank; - The airfoil blank is deformed in the direction Y from the warp tracer line toward the first and second edges of the blank, such that the weft tracer line corresponds to the weft visual reference.

2. The forming method according to claim 1, wherein, The fiber preform includes multiple weft yarn tracers distributed between the bottom and top of the airfoil preform, and wherein multiple weft yarn visual references corresponding to the reference positions of the weft yarn tracers are projected. The following steps are repeated for each weft yarn tracer in order from the bottom to the top of the airfoil preform: - The airfoil blank is deformed in the Y direction from the warp tracer line to the first and second edges of the blank, such that the weft tracer line corresponds to the corresponding weft visual reference, so that all the weft tracer lines correspond to the corresponding weft visual reference.

3. The forming method as described in claim 1, wherein, The deformation of the airfoil blank in the Y direction proceeds from the warp tracer toward the first edge of the blank, such that the weft tracer corresponds to a portion of the weft visual reference, and then proceeds from the warp tracer toward the second edge of the blank, such that the weft tracer corresponds to the corresponding weft visual reference.

4. The forming method according to claim 1, wherein, The projection of the visual reference is performed using laser.

5. The forming method according to claim 1, wherein, The visual reference corresponding to the tracer line includes a line with the same width as the tracer line.

6. The forming method according to claim 1, wherein, The visual reference corresponding to the tracer line includes two lines that define the region corresponding to the reference position of the tracer line.

7. The forming method according to claim 1, wherein, The fiber preform is wetted before deformation to facilitate its deformation.

8. A method for manufacturing turbine blades made of composite materials, comprising: - A fiber blank is produced by three-dimensional weaving of a thread, the fiber blank including a root blank for forming the root of a blade and a blade blank for forming the airfoil of a blade, the fiber blank including a reference surface extending between a first edge and a second edge for forming the leading edge and the trailing edge of the blade, the thread including at least a warp tracer thread and at least one weft tracer thread disposed on the reference surface; - The fiber blank is cut while keeping the tracer line on the reference plane intact to obtain a trimmed fiber blank that can represent the shape and size of the components of the blade; - The fiber blank is formed according to the forming method as described in claim 1 to obtain a shaped fiber preform; - Inject the matrix precursor resin into the fiber preform to impregnate the fiber preform; - The matrix precursor resin in the fiber preform is converted into a matrix to obtain a composite material component comprising a fiber reinforcement that is densified by the matrix and has the shape and size of the blade.

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