REPRODUCIBLE FORMING OF A FIBROID PREFORM

Description

Technical Field

[0001] The invention relates to the manufacture of blades or propellers in composite material comprising a fibrous reinforcement made by three-dimensional weaving and densified by a matrix. Previous technique

[0002] The use of composite materials for the manufacture of blades or propellers, for example for gas turbine blades for aeronautical engines or for industrial turbines, makes it possible to obtain parts with mechanical performance equivalent to or even superior to those made of metal, while having a much lower mass.

[0003] The manufacture of these blades or propellers can begin with the creation of a one-piece fibrous blank by three-dimensional weaving, which is then shaped to obtain a fibrous preform of the blade or propeller to be manufactured. The fibrous preform is then densified using a matrix to obtain the part. An example of a manufacturing process for a blade or propeller made of composite material is described in document FR3046564 or document FR3046563.

[0004] The fiber blank comprises two types of yarns forming a network: warps (which extend along the weaving direction) and wefts (which extend transversely to the weaving direction). The warps are substantially parallel to each other, and the wefts are substantially parallel to each other. Warps and wefts generally intersect at a substantially right angle, thus forming a substantially orthogonal warp-weft network.

[0005] However, the shape of the blades or helices to be manufactured cannot be developed. Thus, when the fiber blank is deformed to obtain a fiber preform, a local loss of orthogonality in the warp-weft network can be observed. This loss of orthogonality is called the off-center angle. The angle measuring the difference between the off-center position of a weft yarn and its original position is called the "off-center angle".

[0006] However, the greater the angle of the undercut, the more the mechanical properties of the resulting fibrous preform will be altered. In tension and compression, an undercut material is more flexible in the weft direction and more rigid in the warp direction. A significant undercut will therefore lead to a relatively substantial loss of mechanical properties in the weft direction. Consequently, it will be necessary to manufacture a thicker fibrous preform than it would be without undercutting, which implies a significant increase in mass that impacts the performance of the turbine or engine.

[0007] The step of deforming the fiber blank into a fiber preform can be carried out using visual guides, allowing control of the arrangement of certain weft or warp yarns. Such a method is described, for example, in document US2016288380A1. However, this step of deforming the fiber blank into a fiber preform is performed manually without an ordered shaping sequence, resulting in significant variability in the location of areas where the blank is not properly aligned from one part to another. Ultimately, this leads to significant variability in the mechanical properties of the parts and different geometries in the parts obtained after the resin injection step into the preform. US 2007 / 092379 A1 discloses a method for shaping a fiber blank extending longitudinally in the X direction and transversely in the Y direction. Description of the invention

[0008] The present invention aims to remedy the aforementioned drawbacks by proposing a predefined sequence for shaping the fibrous blank, allowing for an adapted and reproducible deformation of the blank.

[0009] To this end, the invention proposes a method for shaping a fibrous blank extending longitudinally along an X direction and transversely along a Y direction, obtained by three-dimensional weaving between a plurality of warp yarns and a plurality of weft yarns and intended to form a fibrous preform of a turbomachine blade, the fibrous blank comprising a root blank intended to form the blade root and a blade blank intended to form the blade blade, the fibrous blank comprising a reference face extending in the Y direction between a first edge and a second edge intended to form the leading and trailing edges of the blade, the fibrous blank further comprising a warp tracer yarn extending on the reference face along the X direction from the root blank and at least one weft tracer yarn extending on the reference face along the Y direction between the first and second edges, the method comprising at least: the placement of the fiber blank in a forming mold so that the reference face is visible, the holding of the foot blank in the forming mold, the projection of at least one warp visual marker onto the reference face of the fiber blank corresponding to a reference location of the warp tracer yarn, the deformation of the blade blank from the bottom of the blade blank to the top of the blade blank in the X direction so as to match the warp tracer yarn with the warp visual marker, the projection of at least one weft visual marker onto the reference face of the fiber blank corresponding to a reference location of the weft tracer yarn, the deformation of the blade blank in the Y direction from the warp tracer yarn to the first edge and to the second edge of the blank so as to match the weft tracer yarn with the weft visual marker.

[0010] Thus, the shaping process is predefined and identical for each operator. The deformation from bottom to top and from center to edges makes it particularly effective to obtain identical locations for the trimming areas from one piece to another, and therefore better anticipation of areas with lower mechanical properties in the weave direction.

[0011] According to a particular aspect of the invention, the fibrous blank comprises a plurality of weft tracer yarns distributed between the bottom of the blade blank and the top of the blade blank, and in which a plurality of visual weft markers corresponding to a reference location of the weft tracer yarns are projected, the next step being repeated for each weft tracer yarn in order from the bottom of the blade blank to the top of the blade blank: the deformation of the blade blank in the Y direction from the warp tracer wire to the first edge and to the second edge of the blank so as to match the weft tracer wire with the corresponding visual weft marker, so as to match all the weft tracer threads with the corresponding visual weft marker.

[0012] According to another particular aspect of the invention, the deformation of the blade blank in the Y direction is carried out from the warp tracer wire to the first edge of the blank so as to match the weft tracer wire with a part of the visual weft marker, and then from the warp tracer wire to the second edge of the blank so as to match the weft tracer wire with the corresponding visual weft marker.

[0013] According to another particular aspect of the invention, the projection of the visual markers is carried out by laser.

[0014] According to another particular aspect of the invention, the visual marker corresponding to a tracer wire comprises a line of the same width as said tracer wire.

[0015] According to another particular aspect of the invention, the visual marker corresponding to a tracer wire comprises two lines delimiting an area corresponding to the reference location of said tracer wire.

[0016] According to another particular aspect of the invention, the fibrous blank is moistened before being deformed to facilitate its deformation.

[0017] The invention further relates to a method for manufacturing a turbomachine blade from composite material, comprising: the production of a fibrous blank by three-dimensional weaving of yarns comprising a root blank intended to form the blade root and a blade blank intended to form the blade, the fibrous blank comprising a reference face extending between a first edge and a second edge intended to form the leading edge and the trailing edge of the blade, the yarns comprising a warp tracer yarn and at least one weft tracer yarn arranged at least on the reference surface, the cutting of the fibrous blank leaving intact the tracer yarns located on the reference surface to obtain a trimmed fibrous blank capable of taking the shape and dimensions of the constituent parts of the blade, the shaping of the fibrous blank according to the shaping process according to the invention to obtain a formed fibrous preform, the injection into the fibrous preform of a matrix precursor resin in order to impregnate the fibrous preform,The transformation of the matrix precursor resin in the fibrous preform into a matrix, so as to obtain a composite material part comprising a fibrous reinforcement densified by a matrix and having the shape and dimensions of the blade. Brief description of the drawings

[0018] [ Fig. 1 ] There figure 1 is a schematic perspective view of a fibrous pre-form produced by three-dimensional weaving, intended for the production of a fibrous preform. Fig. 2 ] There figure 2 is a schematic perspective view of a fibrous rough-out obtained after cutting the fibrous pre-rough-out of the figure 1 . [ Fig. 3 ] There figure 3 is a schematic view of a blade obtained after shaping and densifying the fibrous blank of the figure 2 . [ Fig. 4 ] There figure 4 is a schematic perspective view of a shaping mold and a laser projector according to an embodiment of the invention. Fig. 5] There figure 5 is a schematic perspective view of the fibrous outline of the figure 2 arranged without being deformed in the shaping mold of the figure 4 . [ Fig. 6 ] There figure 6 is a schematic perspective view of the fibrous outline of the figure 5 distorted so as to make the warp thread coincide with its visual marker. Fig. 7 ] There figure 7 is a schematic perspective view of the fibrous outline of the figure 6 distorted so as to make the first weft tracer thread coincide with its visual reference. Fig. 8 ] There figure 8 is a schematic perspective view of the fibrous outline of the figure 7 distorted so as to make the second weft tracer thread coincide with its visual reference. Fig. 9 ] There figure 9 is a schematic perspective view of the fibrous outline of the figure 8 distorted so as to make all the tracer wires coincide with their visual reference. Description of the implementation methods

[0019] The invention applies generally to the production of blades or propellers made of composite material for turbomachinery, the blade comprising a fibrous reinforcement densified by a matrix. Embodiments for a blade made of composite material will be described below. The invention remains within the scope of this description even if the composite part produced is a propeller.

[0020] The manufacturing process of a blade made of composite material begins with the creation of a fibrous blank obtained by three-dimensional weaving or by multi-layer weaving.

[0021] By "three-dimensional weaving" or "3D weaving," we mean a weaving method in which at least some of the warp threads interlock with weft threads across multiple weft layers, such as in an "interlock weave." An "interlock weave" is a 3D weave structure where each warp layer interlocks with multiple weft layers, with all threads in the same warp column moving in the same direction within the weave plane. It should be noted that, generally speaking, the roles of the warp and weft threads are interchangeable.

[0022] By "multilayer weaving" we mean here a three-dimensional weave with several layers of weft where the basic weave of each layer is equivalent to a classic 2D fabric weave, such as a plain weave, satin or twill weave, but with certain points of the weave that link the weft layers together.

[0023] The creation of the fibrous blank by 3D weaving makes it possible to obtain a bond between the layers, and thus to have good mechanical strength of the fibrous blank, and therefore of the blade in composite material, in a single textile operation.

[0024] An example of the production of a fibrous blank is now described. In this example, the weaving is carried out on a Jacquard-type loom.

[0025] There figure 1 schematically shows the weaving of a fibrous pre-rough 100 from which a fibrous rough 200 can be extracted ( figure 2 ) allowing, after shaping, a preform of fibrous reinforcement for a blade or propeller of an aeronautical engine.

[0026] The fibrous pre-form 100 is obtained by three-dimensional weaving, or 3D weaving, or by multilayer weaving carried out in a known manner using a Jacquard-type loom on which a bundle of warp yarns or strands 101 is arranged in a plurality of layers, the warp yarns being linked by weft layers 102 also arranged in a plurality of layers. This results in a substantially orthogonal warp-weft network. A detailed example of the production of a fibrous pre-form intended to form the fibrous reinforcement of an aircraft engine blade from a 3D-woven fibrous pre-form is described in detail in documents US7101154, US7241112, and WO2010 / 061140.

[0027] The pre-fiber blank 100 is woven into a strip extending generally in an X direction corresponding to the longitudinal direction of the blade to be produced. The pre-fiber blank 100 extends transversely along a Y direction, and in thickness along a Z direction perpendicular to the X and Y directions.

[0028] In the pre-fiber blank 100, the fiber blank 200 has a variable thickness determined according to the longitudinal thickness and profile of the blade to be produced. In its portion intended to form a root preform, the fiber blank 200 has an extra thickness 203 determined according to the thickness of the blade root to be produced. The fiber blank 200 extends into a portion of decreasing thickness 204 intended to form the blade strut, and then into a portion 205 intended to form the blade. The portion 205 has, in the Y direction, a profile with variable thickness between its edge 205a, intended to form the leading edge of the blade, and its edge 205b, intended to form the trailing edge of the blade to be produced. Part 205 extends in the Z direction between a first face 205c intended to form the intrados of the blade profile and a second face 205d intended to form the extrados of the blade profile.

[0029] The fibrous blank 200 is woven in one piece. In sections of varying thickness in the fibrous blank, such as the decreasing thickness section 204, the decrease in blank thickness can be achieved by progressively removing weft layers during weaving. Once the weaving of the blank 200 into the pre-blank 100 is complete, the non-woven yarns are cut. This results in the blank 200 shown in the diagram. figure 2 and woven in one piece.

[0030] As illustrated on the figure 2The fiber blank 200 comprises structural yarns 101 and 102, used for weaving the blank structure, and visually identifiable tracer yarns 101a, 102a, 102b, and 102c. The tracer yarns 101a, 102a, 102b, and 102c, incorporated during the weaving of the fiber blank 100, are located primarily on the surface of the fiber blank 200. Tracer yarn 101a is a warp yarn. Tracer yarns 102a, 102b, and 102c are weft yarns.

[0031] The tracer warp wire 101a can be placed substantially equidistant from the edges 205a and 205b of the fibrous blank intended to form the leading edge and trailing edge of the blade or propeller to be manufactured.

[0032] There figure 3 illustrates the location of the tracer wires on the part manufactured by shaping the fibrous blank and densifying the resulting preform with a matrix.

[0033] In the example shown on the figures 2 And3 There is only one warp tracer yarn and three weft tracer yarns. Of course, the invention remains within the scope of this invention even if the number of weft tracer yarns is less than or greater than three.

[0034] According to a particular embodiment of the invention, the structural wires can be carbon fibers, and the tracer wires can be glass fibers, Kevlar fibers, or fibers made of a carbon-glass blend. Thus, the tracer wires appear light in color against the rest of the blank, which is dark.

[0035] Furthermore, the presence of these tracer wires can facilitate or standardize the cutting of the pre-fiber blank to obtain the fiber blank. Examples of using tracer wires to perform such cutting are described in document US2015165571A1.

[0036] As illustrated on the figures 4 And 5The fibrous blank 200 is placed in a shaping mold 6 without being deformed. The shaping mold 6 has a cavity 60 having the shape of the desired fibrous preform.

[0037] The fibrous blank 200 is positioned in the shaping mold by placing the part 203 of the fibrous blank intended to form the blade foot in the part of the cavity 60 of the mold 6 intended to receive it.

[0038] According to a particular embodiment of the invention, the fibrous blank 200 thus arranged in the mold without being deformed can be moistened, for example with distilled water.

[0039] The foot of the fiber blank 200 is then secured or fixed in the mold 6, for example by means of a pre-compaction jaw 61. Securing the foot of the blank can pre-compact it and allow some of the fibers of the foot to be locked in the desired position. By securing the fiber blank at the foot, and not at the part intended to form the blade, a smooth transition is obtained between the secured and unsecured areas, thus preventing buckling of the fibers located at the boundary between the secured and unsecured areas.

[0040] When the fibrous blank is placed in the shaping mold 6, the blank can be placed in a configuration which deforms it by applying a rotation around an X axis parallel to the main direction while keeping the foot of the blank fixed, which results in twisting the blade of the blank around this axis.

[0041] In some cases, it may also be provided that the shaping mold has a sliding movable part intended to come and position itself against the free end of the foot of the blank in order to exert a constraint which produces the desired deformation of this portion of the blank, or avoids certain types of deformation in this part while a deformation is exerted on other portions of the blank.

[0042] Various systems for locating and positioning the draft can be used, in particular a laser projector 5 (see the figure 4This system projects a beam of light onto the ideal location of one or more tracer wires, making it easy to move the corresponding tracer wire accordingly to achieve the predetermined positioning. The light beam can be a laser of the same width as the tracer wire it corresponds to. The light beam can be a laser projecting over a wide area, defining the reference zone of the corresponding tracer wire. The light beam can be a split laser projecting two lines, defining the reference zone of the corresponding tracer wire.

[0043] The alignment of the tracer wires of the fibrous rough 200 with their visual reference is carried out in several stages in a well-defined order.

[0044] According to a first step illustrated on the figure 6The laser projector 5 begins by indicating at least the visual marker 501a of the warp wire. This visual marker 501a of the warp wire corresponds to the reference position of the warp wire 101a on the fiber preform being shaped in the forming mold. Thus, the fiber blank 200 must be deformed so that the warp wire 101a on its face coincides with the visual marker 501a of the warp wire.

[0045] The fibrous blank 200 is deformed from the bottom of the blank blade to the top of the blank blade, i.e. in the X direction of increasing abscissas, so as to superimpose the warp tracer wire 101a of the blank 200 with the visual reference 501a of the warp tracer wire.

[0046] By deforming the blank 200 from the bottom up, that is, from the base of the blank to the upper edge of the blade, the misalignment is limited at the base and the bottom of the blade. Indeed, as the fibrous blank 200 is deformed away from the constrained area, the misalignment becomes increasingly significant. Since the material properties are usually less favorable at the base and its junction with the blade, it is preferable to limit the misalignment in these areas and transfer it to the top of the blade where the material characteristics are better and allow for greater tolerance to misalignment. Furthermore, this deformation from the bottom of the blade of the blank 200 to the top of the blade facilitates the repeatability of the deformation with a controlled arrangement of the misalignment zones.

[0047] According to a second step illustrated on the figure 7The laser projector 5 then indicates at least the visual reference mark 502a of the first weft tracer yarn, starting from the bottom of the blank blade 200, that is, the first weft tracer yarn in the X direction of increasing abscissas. This visual reference mark 502a of the first weft tracer yarn corresponds to the reference position of the first weft tracer yarn 102a on the fiber preform being shaped in the forming mold. Thus, the fiber blank 200 must be deformed so that the first weft tracer yarn 102a on its face coincides with the visual reference mark 502a of the first weft tracer yarn. Preferably, the laser projector 5 also indicates the visual reference mark 501a of the warp tracer yarn.

[0048] The fibrous blank 200 is deformed from the warp tracer wire 101a towards the edge 205a of the fibrous blank 200 intended to form the leading edge of the blade, that is to say in the direction of the increasing ordinates Y, so as to superimpose the first weft tracer wire 102a of the blank 200 with the part of the visual marker 502a of the first weft tracer wire located between the warp tracer wire 101a and the edge 205a of the fibrous blank 200 intended to form the leading edge.

[0049] The fibrous blank 200 is then deformed from the warp tracer wire 101a towards the edge 205b of the fibrous blank 200 intended to form the trailing edge of the blade, that is to say in the direction of the decreasing ordinates Y, so as to superimpose the first weft tracer wire 102a of the blank 200 with the part of the visual marker 502a of the first weft tracer wire located between the warp tracer wire 101a and the edge 205b of the fibrous blank intended to form the trailing edge.

[0050] After deforming the fibrous blank 200 on both sides of the warp tracer yarn 101a, the first weft tracer yarn 102a is precisely aligned along its entire length with the visual marker 502a of the weft tracer yarn. At the end of this second step, the warp tracer yarn 101a preferably remains aligned with its corresponding visual marker 501a.

[0051] According to a third step illustrated on the figure 8The laser projector 5 then indicates at least the visual reference mark 502b of the second weft tracer wire, starting from the bottom of the blank blade 200, that is, the second weft tracer wire in the X direction of increasing abscissas. This visual reference mark 502b of the second weft tracer wire corresponds to the reference position of the second weft tracer wire 102b on the fiber preform being shaped in the forming mold. Thus, the fiber blank 200 must be deformed so that the second weft tracer wire 102b on its face coincides with the visual reference mark 502b of the second weft tracer wire. Preferably, the laser projector 5 also indicates the visual reference mark 501a of the warp tracer wire and the reference mark 502a of the second weft tracer wire.

[0052] The fibrous blank 200 is deformed from the warp tracer wire 101a towards the edge 205a of the fibrous blank 200 intended to form the leading edge of the blade, that is to say in the direction of the increasing ordinates Y, so as to superimpose the second weft tracer wire 102b of the blank 200 with the part of the visual marker 502b of the second weft tracer wire located between the warp tracer wire 101a and the edge 205a of the fibrous blank 200 intended to form the leading edge.

[0053] The fibrous blank 200 is then deformed from the warp tracer wire 101a towards the edge 205b of the fibrous blank 200 intended to form the trailing edge of the blade, i.e. in the direction of the decreasing ordinates Y, so as to superimpose the second weft tracer wire 102b of the blank 200 with the part of the visual marker 502b of the second weft tracer wire located between the warp tracer wire 101a and the edge 205b of the fibrous blank intended to form the trailing edge.

[0054] After deforming the fibrous blank 200 on both sides of the warp tracer yarn 101a, the second weft tracer yarn 102b is precisely superimposed along its entire length on the corresponding visual marker 502b of the weft tracer yarn. At the end of this third step, the warp tracer yarn 101a preferably remains superimposed on its corresponding visual marker 501a, and the first weft tracer yarn 102a preferably remains superimposed on its visual marker 502a.

[0055] According to a fourth step illustrated on the figure 9The laser projector 5 then indicates at least the visual marker 502c of the third weft marker yarn, starting from the bottom of the blank blade 200, that is, the second weft marker yarn in the X direction of increasing abscissas. This visual marker 502c of the third weft marker yarn corresponds to the reference position of the third weft marker yarn 102c on the fiber preform being shaped in the forming mold. Thus, the fiber blank 200 must be deformed so that the third weft marker yarn 102c on its face coincides with the visual marker 502c of the third weft marker yarn. Preferably, the laser projector 5 also indicates the visual marker 501a of the warp marker yarn, the marker 502a of the second weft marker yarn, and the marker 502b of the third weft marker yarn.

[0056] The fibrous blank 200 is deformed from the warp tracer wire 101a towards the edge 205a of the fibrous blank 200 intended to form the leading edge of the blade, that is to say in the direction of the increasing ordinates Y, so as to superimpose the third weft tracer wire 102c of the blank 200 with the part of the visual marker 502c of the third weft tracer wire located between the warp tracer wire 101a and the edge 205a of the fibrous blank 200 intended to form the leading edge.

[0057] The fibrous blank 200 is then deformed from the warp tracer wire 101a towards the edge 205b of the fibrous blank 200 intended to form the trailing edge of the blade, that is to say in the direction of the decreasing ordinates Y, so as to superimpose the third weft tracer wire 102c of the blank 200 with the part of the visual marker 502c of the third weft tracer wire located between the warp tracer wire 101a and the edge 205b of the fibrous blank intended to form the trailing edge.

[0058] After deforming the fibrous blank 200 on both sides of the warp tracer yarn 101a, the third weft tracer yarn 102c is precisely superimposed along its entire length on the corresponding visual marker 502c of the weft tracer yarn. At the end of this third step, the warp tracer yarn 101a preferably remains superimposed on its corresponding visual marker 501a, the first weft tracer yarn 102a preferably remains superimposed on its visual marker 502a, and the second weft tracer yarn 102b preferably remains superimposed on its visual marker 502b.

[0059] In the example illustrated on the figures 4 to 9 There is only one warp tracer yarn and three weft tracer yarns. Of course, the invention remains within the scope of this invention even if the number of weft tracer yarns is less than or greater than three.

[0060] For each additional weft tracer yarn located above the preceding weft tracer yarn in the direction of increasing x-coordinates, the procedure is the same as in step four. The laser projector must display the visual marker corresponding to the additional weft tracer yarn, preferably displaying the visual marker corresponding to the warp tracer yarn and the preceding weft tracer yarns. The fiber blank 200 is then deformed from the warp tracer yarn 101a towards the edge 205a of the fiber blank 200 intended to form the leading edge of the blade, and then the fiber blank 200 is deformed from the warp tracer yarn 101a towards the edge 205b of the fiber blank 200 intended to form the trailing edge of the blade, so that the additional weft yarn is superimposed along its entire length with the corresponding visual marker.At the end of this additional step, the warp tracer yarn preferably remains superimposed on its corresponding visual marker and the previous weft tracer yarns preferably remain superimposed on their corresponding visual marker.

[0061] By deforming the fibrous blank 200 from the warp tracer wire 101a, preferably positioned towards the center of the fibrous blank 200, towards the edges of the blank, we ensure good repeatability of the deformation and good control of the location of the unframing zones, which will be mostly located on the edges of the blank.

[0062] By deforming the 200 fiber blank to align the weft tracer yarns with their visual markers from the bottom of the blank blade to the top, the misalignment at the root and bottom of the blade is minimized. Indeed, as the 200 fiber blank is deformed away from the constrained area, i.e., the blank root, the misalignment becomes increasingly significant. Since material properties are typically less favorable at the root and its junction with the blade, it is preferable to limit the misalignment in these areas and transfer it to the top of the blade where the material characteristics are better, allowing for greater tolerance to misalignment. Furthermore, this deformation from the bottom of the 200 blank blade to the top facilitates the repeatability of the deformation with a controlled arrangement of the misalignment zones.

[0063] The invention remains within the scope of practice if the roles of the blank edge intended to form the leading edge of the blade and the blank edge intended to form the trailing edge are exchanged or alternated during the preceding steps. The deformation of the fibrous blank from the warp tracer yarn to a first blank edge, and then from the warp tracer yarn to a second blank edge for each weft tracer yarn, simplifies the deformation of the fibrous blank in the Y-direction. A single operator can easily and quickly repeat this sequence of deformations while maintaining good repeatability and identical placement of the deformation zones from one blade to another. This sequence of deformations constitutes a preferred embodiment of the invention.

[0064] However, the invention remains within the scope of practice if the deformation of the fiber blank in the Y-direction is carried out simultaneously or alternately on either side of the warp marker yarn towards each edge to superimpose a weft marker yarn onto its corresponding visual reference. Nevertheless, this sequence of deformations is relatively more difficult for a single operator to implement, while still maintaining good repeatability.

[0065] Once the fiber blank is fully deformed, all the visual markers of the tracer wires—with or without tolerances—can be displayed again to verify that all tracer wires are correctly aligned with their corresponding visual markers. Minor deformations can be made to ensure satisfactory alignment of all tracer wires with their visual markers.

[0066] If the fibrous blank has been moistened before the deformation steps, it can be dried after being deformed.

[0067] After these deformation steps, the deformed fibrous blank can be compacted in a compaction mold, possibly preceded by a pre-compaction step. These pre-compaction or compaction steps are described, for example, in US2016243777A1 or US2016288380A1. The compaction mold may include the shaping mold.

[0068] Thus, a fibrous preform is obtained after shaping and possibly compacting the fibrous blank.

[0069] The fibrous preform is then impregnated with a thermosetting resin, which is polymerized by heat treatment. For example, the well-known injection or transfer molding process known as RTM (Resin Transfer Molding) is used for this purpose. According to the RTM process, a resin, such as a thermosetting resin, is injected through an injection port into the internal space occupied by the preform within the injection mold. This configuration establishes a pressure gradient between the lower part of the preform, where the resin is injected, and the upper part of the preform, located near the discharge port. In this way, the resin, injected at approximately the lower part of the preform, gradually impregnates the entire preform as it circulates through it until it reaches the discharge port, through which the excess resin is expelled.Of course, injection molding tooling can include multiple injection ports and multiple discharge ports.

[0070] Resins suitable for RTM processes are well-established. They preferably have a low viscosity to facilitate injection into the fibers. The choice of temperature class and / or chemical composition of the resin is determined according to the thermomechanical stresses to which the part will be subjected. Once the resin has been injected throughout the reinforcement, it is cured by heat treatment according to the RTM process.

[0071] After injection and polymerization, the blade is demolded. It may then undergo a post-curing cycle to improve its thermomechanical properties. Finally, the blade is trimmed to remove excess resin, and chamfers may be machined. This results in a composite part consisting of a fibrous reinforcement densified by a matrix.

[0072] Protective layers can be glued onto the resulting composite part.

Claims

1. A method for shaping a fiber blank (200) extending longitudinally along a direction X and transversally along a direction Y, obtained by three-dimensional weaving between a plurality of warp threads (101) and a plurality of weft threads (102) and intended to form a fiber preform for a turbomachine blade, the fiber blank (200) comprising a root blank (203) intended to form the blade root and a airfoil blank (205) intended to form the blade airfoil, the fiber blank (200) comprising a reference face (205c) extending in the direction Y between a first edge (205a) and a second edge (205b) intended to form the leading edge and the trailing edge of the blade, the fiber blank (200) further comprising a warp tracer thread (101a) extending over the reference face (205c) along the direction X from the root blank (203) and at least one weft tracer thread (102a, 102b, 102c) extending over the reference face (205c) along the direction Y between the first edge (205a) and the second edge (205b), the method comprising at least: - the placement of the fiber blank (200) in a shaping mold (6) in such a way that the reference face (205c) is visible, - the retaining of the root blank (203) in the shaping mold (6), - the projection of at least one visual reference of the warp (501a) on the reference face (205c) of the fiber blank (200) corresponding to a reference location of the warp tracer thread (101a), - the deformation of the airfoil blank (205) from the bottom of the airfoil blank to the top of the airfoil blank in the direction X such as to make the warp tracer thread (101a) correspond with the warp visual reference (501a), - the projection of at least one weft visual reference (502a, 502b, 502c) on the reference face (205c) of the fiber blank (200) corresponding to a reference location of the weft tracer thread (102a, 102b, 102c), - the deformation of the airfoil blank (205) in the direction Y from the warp tracer thread (101a) to the first edge (205a) and to the second edge (205b) of the blank (200) such as to make the weft tracer thread (102a, 102b, 102c) correspond with the weft visual reference (502a, 502b, 502c).

2. The shaping method as claimed in claim 1, wherein the fiber blank (200) comprises a plurality of weft tracer threads (102a, 102b, 102c) distributed between the bottom of the airfoil blank (205) and the top of the airfoil blank (205) and wherein a plurality of weft visual references (502a, 502b, 502c) corresponding to a reference location of the weft tracer threads (102a, 102b, 102c) are projected, the following step being repeated for each weft tracer thread in order from the bottom of the airfoil blank to the top of the airfoil blank: - the deformation of the airfoil blank (205) in the direction Y from the warp tracer thread (101a) to the first edge (205a) and to the second edge (205b) of the blank (200) such as to make the weft tracer thread (102a, 102b, 102c) correspond with the corresponding weft visual reference (502a, 502b, 502c),such as to make all the weft tracer threads (102a, 102b, 102c) correspond with the corresponding weft visual references (502a, 502b, 502c).

3. The shaping method as claimed in claim 1 or 2, wherein the deformation of the airfoil blank (205) in the direction Y is done from the warp tracer thread (101a) to the first edge (205a) of the blank (200) such as to make the weft tracer thread (102a, 102b, 102c) correspond with a part of the weft visual reference (502a, 502b, 502c), then from the warp tracer thread (101a) to the second edge (205b) of the blank (200) such as to make the weft tracer thread (102a, 102b, 102c) correspond with the corresponding weft visual reference (502a, 502b, 502c).

4. The shaping method as claimed in any of claims 1 to 3, wherein the projection of the visual references (501a, 502a, 502b, 502c) is done by laser.

5. The shaping method as claimed in any of claims 1 to 4, wherein the visual reference (501a, 502a, 502b, 502c) corresponding to a tracer thread (101a, 102a, 102b, 102c) comprises a line of the same width as said tracer thread.

6. The shaping method as claimed in any of claims 1 to 5, wherein the visual reference (501a, 502a, 502b, 502c) corresponding to a tracer thread (101a, 102a, 102b, 102c) comprises two lines delimiting an area corresponding to the reference location of said tracer thread.

7. The shaping method as claimed in any of claims 1 to 6, wherein the fiber blank (200) is moistened before being deformed to facilitate its deformation.

8. A method for manufacturing a turbomachine blade made of composite material, comprising: - the production of a fiber blank (200) by three-dimensional weaving of threads comprising a root blank (203) intended to form the blade root and a blade blank (205) intended to form the blade airfoil, the fiber blank (200) comprising a reference face (205c) extending between a first edge (205a) and a second edge (205b) intended to form the leading edge and the trailing edge of the blade, the threads comprising a warp tracer thread (101a) and at least one weft tracer thread (102a, 102b, 102c) disposed at least on the reference surface (205c), - the cutting-out of the fiber blank (200) while leaving intact the tracer threads (101a, 102a, 102b, 102c) located on the reference surface (205c) to obtain a trimmed fiber blank, able to take the shape and dimensions of the component parts of the blade, - the shaping of the fiber blank (200) according to the method for shaping as claimed in any of claims 1 to 7 to obtain a shaped fiber preform, - the injection into the fiber preform (200) of a matrix precursor resin in order to impregnate the fiber preform, - the transformation of the matrix precursor resin in the fiber preform into a matrix such as to obtain a composite material part comprising a fiber reinforcement densified by a matrix and having the shape and dimensions of the blade.