Method for producing a stitch-reinforced blade

Abstract

The invention relates to a method for manufacturing a propeller blade or vane (3), the method comprising: - producing a fibre blank (100) comprising a gap (103) separating a first skin (110) from a second skin (120), wherein the gap (103) extends at least partially from an edge (100a) intended to form the leading edge; - inserting an insert (40) into the internal cavity (103a) of the fibre blank (100) so as to form a fibre preform (10); - stitching the first skin (110) to the second skin (120); - densifying the preform (10) in order to obtain a composite material part (1) having the shape of the blade or vane (3) to be obtained; - adding a leading edge reinforcement element (2) at least partially covering the one or more stitched regions (61, 62).

Description

Description Title of the invention: Method for manufacturing a blade reinforced by sewing Technical Field

[0001] The present invention relates to the field of propeller blades or vanes for aircraft such as those present on turbomachines. Prior art

[0002] The production of blades from organic matrix composite (OMC) or ceramic matrix composite (CMC) materials is well known. Such blades include a fiber reinforcement densified by an organic or ceramic matrix. Organic matrix composite (OMC) or ceramic matrix composite (CMC) materials are lighter than most metals while retaining good mechanical properties. This improves the efficiency of the turbomachine, which allows for a reduction in fuel consumption.

[0003] The fiber reinforcement of turbomachine blades is formed by a fiber preform. The fiber preform is conventionally obtained by weaving a plurality of fibers, for example by three-dimensional weaving.

[0004] Document US 2005 / 0084377 describes a method for manufacturing a turbomachine blade from a monolithic composite material, the blade being manufactured by three-dimensional weaving of a fiber preform and densification of the preform by a matrix. This method makes it possible to obtain blades having very high mechanical strength, in particular with respect to shocks or impacts, without risk of delamination. However, monolithic blades or propeller blades have many disadvantages, in particular in the case of large blades or propeller blades.

[0005] Manufacturing processes for manufacturing blades or vanes with the introduction of one or more inserts into a dry woven fiber preform by debonding have been developed.

[0006] However, the debonds have weaker mechanical properties than the rest of the woven preform and thus constitute areas of weakness in the resulting blade. Statement of the invention

[0007] The invention provides a method for manufacturing a turbomachine propeller blade or vane, the method comprising:

[0008] - the production of a fiber blank by three-dimensional weaving of fibers, said blank comprising a separation separating a first skin from a second skin of the fiber blank so as to form an internal housing between the skins, the separation extending at least in part from an edge of the fiber blank intended to form the leading edge of the blade or vane,

[0009] - the introduction of an insert into the internal housing of the fiber blank so as to form a fiber preform, the insert filling only part of the internal housing of the blank,

[0010] - holding the fiber preform in a molding cavity of an injection tool having the shape of the blade or propeller blade to be manufactured,

[0011] - injecting a resin into the molding cavity containing the fiber preform and transforming the resin into a matrix by heat treatment to obtain a part made of composite material having the shape of the blade or vane to be obtained and comprising a leading edge, and

[0012] - the addition of a reinforcement element reported at the leading edge,

[0013] the method being characterized in that it comprises an operation of sewing the first skin to the second skin by sewing threads in at least one zone devoid of insert, said zone comprising the edge intended to form the leading edge of the blade or vane to be obtained, the sewing operation being carried out after the introduction of the insert and before the injection of the resin, and in that the reinforcing element at least partially covers the seam(s) produced.

[0014] Thus, the present invention makes it possible to reinforce the detachments necessary for the insertion of inserts by carrying out a sewing operation. The invention is particularly interesting when the shape of the insert requires a large opening to allow insertion without filling the entire housing. permitted by the debonding. In addition, by placing at least part of the seam(s) under the leading edge reinforcement element, the resistance of the debonding located under the leading edge is increased in relation to the mechanical stresses undergone while improving resistance to erosion.

[0015] According to one aspect of the invention, the stitching threads may follow a crenellated path.

[0016] According to one aspect of the invention, the seam(s) may be made at least in part by tufting.

[0017] According to one aspect of the invention, the seam(s) may be made at least in part with invisible stitches.

[0018] According to one aspect of the invention, the seam(s) may be made at least in part with one-sided stitches.

[0019] According to one aspect of the invention, the delinking also extends from an edge of the fibrous blank intended to form the trailing edge of the blade or vane, the area devoid of insert comprising the edge intended to form the trailing edge of the blade or vane to be obtained so that the first skin is sewn to the second skin by the stitching threads at this edge intended to form the trailing edge.

[0020] According to one aspect of the invention, at least one of the seams may extend along the edge intended to form the trailing edge.

[0021] According to one aspect of the invention, the fibrous blank may extend in a longitudinal direction corresponding to the span direction of the blade or vane to be manufactured between a lower edge and an upper edge corresponding to the head of the blade or vane to be manufactured, the delinking extending from the lower edge of the fibrous blank.

[0022] According to one aspect of the invention, at least one of the seams may extend along the edge intended to form the leading edge.

[0023] According to one aspect of the invention, all of the seams may extend along the edge intended to form the leading edge and be covered by the reinforcing element. Brief description of the drawings

[0024] [Fig. 1] Figure 1 is a schematic perspective view illustrating the weaving of a fiber blank for the manufacture of a blade.

[0025] [Fig. 2A] Figure 2A is an enlarged partial sectional view of an assembly of layers of wires forming the blank of Figure 1.

[0026] [Fig. 2B] Figure 2B is another enlarged partial sectional view of an array of wire layers forming the blank of Figure 1.

[0027] [Fig. 3] Figure 3 is an exploded view showing the production of a fiber preform from the blank of Figure 1.

[0028] [Fig. 4] Figure 4 is a perspective view of the fiber preform obtained in Figure 3.

[0029] [Fig. 5] Figure 5 is a perspective view of the fiber preform of Figure 4 on which a sewing operation is carried out.

[0030] [Fig. 6] Figure 6 is a sectional view of Figure 5.

[0031] [Fig. 7] Figure 7 is another sectional view of Figure 5.

[0032] [Fig. 8] Figure 8 is an exploded perspective schematic view showing an injection tool and the placement of the preform of Figures 5 and 6 therein.

[0033] [Fig. 9] Figure 9 is a schematic perspective view showing the injection tooling of Figure 8 closed during a resin injection step.

[0034] [Fig. 10] Figure 10 is a schematic perspective view showing the assembly of the reinforcing element on the leading edge. Description of the embodiments

[0035] The invention applies generally to different types of propeller blades or vanes used in aircraft engines. The invention finds an advantageous but not exclusive application in large propeller blades or vanes which are intended to be integrated into pivoting or variable pitch systems. Such propeller blades or vanes are generally provided of a foot having both a small footprint (compact shape) and good resistance to tensile, bending and circumferential compression forces. The blade according to the invention may in particular constitute a blade for shrouded moving wheels such as fan blades or a blade for unshrouded moving wheels as in so-called "open rotor" aeronautical engines.

[0036] In the remainder of the description, an example of implementation of the method of the invention is described in relation to the manufacture of a blade for an unducted mobile wheel. However, the example of embodiment also applies to the manufacture of other types of blade or propeller blade for aircraft turbomachines.

[0037] Figure 1 shows very schematically a fiber blank 100.

[0038] The fiber blank 100 is produced by three-dimensional weaving between a plurality of warp threads 101 and a plurality of weft threads 102. The fiber blank 100 can be produced in a well-known manner using a Jacquard type loom. By "three-dimensional weaving" (3D) is meant here a weaving mode by which at least some of the warp threads bind weft threads on several weft layers. It is considered that a fiber blank produced by three-dimensional weaving can comprise another type of weaving on its surface, for example two-dimensional weaving, in order to improve its surface condition. The fiber blank can for example have a three-dimensional weaving weave of the interlock or multi-satin type. Different usable three-dimensional weaving modes are described in document WO 2006 / 136755.

[0039] In the example shown, the three-dimensional weave is an interlock weave. An interlock weave here means a weave pattern in which each layer of weft yarns binds together multiple layers of warp yarns, with all yarns in a single weft column moving in the plane of the weave.

[0040] The fiber blank 100 may comprise a plurality of threads or filaments of various types, in particular ceramic or carbon threads or a mixture of such threads. Preferably, the fiber blank may be made from silicon carbide fibers. Generally, the fiber blank may also be made from fibers made of the following materials: alumina, mullite, silica, an aluminosilicate, a borosilicate, carbon, or a mixture of several of these materials.

[0041] As the fiber blank 100, the thickness and width of which vary, is woven, a certain number of warp threads are not woven, which makes it possible to define the desired, continuously variable contour and thickness of the blank 100. An example of evolving three-dimensional weaving, in particular making it possible to vary the thickness of the blank between a first edge intended to form the leading edge and a second edge of lesser thickness and intended to form the trailing edge, is described in document EP 1 526 285.

[0042] The fiber blank 100 extends in a first direction between a lower edge 100c and an upper edge. The first direction will correspond, after shaping the fiber blank 100, to the span direction of the blade to be obtained. The fiber blank 100 extends in a second direction perpendicular to the first direction between a first edge 100a and a second edge 100b. The second direction will correspond, after shaping the fiber blank 100, to the chord direction of the blade to be obtained. The first edge 100a of the fiber blank 100 is intended to form the leading edge of the blade to be obtained. The second edge 100b of the fiber blank 100 is intended to form the trailing edge of the blade to be obtained.

[0043] During weaving, as illustrated in FIG. 1, a separation 103 is produced inside the fiber blank between two successive layers of warp threads. The separation 103 thus separates a first skin 110 from a second skin 120 of the fiber blank 100.

[0044] A 3D interlock weaving mode of the blank 100 is shown schematically by Figures 2A and 2B. Figure 2A is an enlarged partial view of two successive warp sectional planes in a portion of the blank 100 not having a delink, that is to say in an area of ​​the blank located outside the delink 103, while Figure 2B shows two successive warp sectional planes in the portion of the blank 100 having the delink 103.

[0045] In this example, the blank 100 comprises 6 layers of warp yarns 101 extending in the X direction. In Figure 2A, the 6 layers of warp yarns are linked by weft yarns T1 to T5. In Figure 2B, 3 layers of warp yarns 101 forming the set of yarn layers 105 are linked together by two weft yarns T1, T2, just as the 3 layers of warp yarns forming the set of yarn layers 106 are linked by two weft yarns T4 and T5. In other words, the fact that the weft yarns T1, T2 do not extend into the yarn layers 106 and that the weft yarns T4, T5 do not extend into the yarn layers 105 ensures the delinking 103 which separates the sets of warp yarn layers 105, 106 from each other.

[0046] At the end of weaving, the warp and weft threads are cut, for example using a pressurized water jet, at the limit of the woven mass to extract the dry blank 100 shown in Figure 3 as it results from the three-dimensional weaving and before any shaping. The uncoupling 103 extends over a uncoupling zone 104. The uncoupling zone 104 formed during weaving makes it possible to form the two skins 110 and 120 woven independently of each other delimiting an internal housing 103a inside the blank 100. The uncoupling zone 104 makes it possible to form an internal housing 103a allowing the introduction of one or more inserts, inside the fiber blank 100 for the purpose of forming the preform of the aerodynamic profile structure. The first skin 110 and the second skin 120 may be intended to form respectively the fibrous reinforcement of the extrados and the intrados of the blade to be produced.

[0047] According to the invention, the decoupling zone 104 comprises a portion of the first edge 100a of the fiber blank 100 intended to form the leading edge. In the example illustrated in the figures, the decoupling zone 104 also comprises a portion of the lower edge 100c of the fiber blank 100.

[0048] Thus, in accordance with the invention, the internal housing 103a is open on the first edge 100a of the fiber blank 100. In the example illustrated in the figures, the internal housing 103a is also open on the lower edge 100c of the blank 100. The internal housing 103a does not open onto the second edge 100b of the blank 100 in the example illustrated. This does not, of course, go beyond the scope of the invention if the internal housing 103a opens onto the lower edge 100c and onto the second edge 100b of the blank 100. It is also not outside the scope of the invention if the internal housing 103a does not open onto the lower edge 100c and opens onto the second edge 100b of the blank 100. The internal housing 103a may possibly open onto the upper edge of the blank 100.

[0049] In the example illustrated in the figures, the fiber blank 100 is intended to form the fiber reinforcement of the aerodynamic profile of the blade to be produced. Thus, the fiber blank 100 is devoid of a portion intended to form the fiber reinforcement of the root of the blade to be produced. However, it does not depart from the scope of the invention if the fiber blank 100 comprises a portion intended to form the fiber reinforcement of the root of the blade to be produced.

[0050] As illustrated in FIG. 3, an insert 40 is inserted into the fiber blank 100 so as to obtain a fiber preform 10.

[0051] As illustrated in Figures 3 and 4, the insert 40 comprises a first portion 41 intended to be present inside the aerodynamic profile of the blade and a second portion 42 intended to form the root of the blade. Thus, the first portion 41 of the insert 40 is inserted into the internal housing 103a. The entirety of the first portion 41 of the insert 40 is present in the internal housing 103a. The second portion 42 of the insert remains outside the fiber blank 100.

[0052] It is of course not beyond the scope of the invention if the entire insert 40 is inserted into the fiber blank 100. It is also not beyond the scope of the invention if the insert comprises a first portion intended to be present inside the aerodynamic profile of the blade and a second portion intended to be present inside the root of the blade. It is also not beyond the scope of the invention if several inserts are inserted into the same uncoupling, or if several inserts are inserted into several uncouplings.

[0053] According to the invention, when the insert 40 is introduced into the fiber blank 100, the entire debonding zone does not comprise the insert 40. The insert 40 does not entirely fill the internal housing 103a. Thus, the internal housing 103a comprises at least one portion 104a filled by the insert 40 and one or more portions 104b, 104c without insert 40. In the portion 104a filled by the insert 40, the first and second skins 110 and 120 are spaced apart from each other by the insert 40. In the portion 104a filled by the insert 40, the first and second skins 110 and 120 are in contact with the insert 40. In the portion(s) 104b, 104c without insert 40, the first and second skins 110 and 120 are not in contact with the insert 40. In the portion(s) 104b, 104c without insert 40, the first and second skins 110 and 120 are not separated by the insert 40.

[0054] According to the invention, the first and second skins 110 and 120 are sewn to each other in at least one portion 104b, 104c devoid of insert 40 of the internal housing 103a.

[0055] In the example illustrated in Figures 5 to 7, the first and second skins 110 and 120 are sewn to each other in the portions 104b, 104c without insert 40 of the internal housing 103a. The first and second skins 110 and 120 are sewn to each other by one or more sewing fibers or threads 6. A seam is formed by one or more linked threads traveling the same continuous path.

[0056] The first and second skins 110 and 120 may be sewn by one or more first seams 61 extending along the second direction, i.e. along the chord direction of the blade to be produced. The first and second skins 110 and 120 may also be sewn by one or more second seams 62 extending along the first direction, i.e. along the span direction of the blade to be produced. In particular, the second seam(s) 62 may extend along the first edge 100a, intended to form the leading edge of the blade.

[0057] Figure 6 is a sectional view of the fiber preform 10 of Figure 5 along a plane perpendicular to the first direction, that is to say perpendicular to the span direction of the blade to be produced, illustrating an example of a first seam 61. Figure 7 is a partial sectional view of the fiber preform 10 of Figure 5 along a plane perpendicular to the second direction, that is to say perpendicular to the chord direction of the blade to be produced, illustrating an example of a second seam 62.

[0058] It is of course not beyond the scope of the invention if the seams extend in other directions. In the example illustrated in Figures 5 to 7, there are both one or more first seams 61 and one or more seams 62. It is of course not beyond the scope of the invention if the fiber blank 100 is sewn only by one or more first seams 61 or only by one or more second seams 62.

[0059] In the example illustrated in Figures 6 and 7, the seam(s) produced has a crenellation shape. In particular, the first and / or second seams 61 and 62 may have a crenellation shape. Thus, the sewing fiber(s) or thread(s) 6 comprise in length the alternating succession of first sewing fiber portions 6a and second sewing fiber portions 6b. The first sewing fiber portions 6a are perpendicular to the second sewing fiber portions 6b. The second sewing fiber portions 6b extend in a third direction perpendicular to the first and second directions, i.e. in the thickness direction of the blade to be produced.

[0060] Adding fibers or stitching threads along a path regularly orthogonal to the debonding improves the strength of the debonding and limits the propagation of cracks in the plane of the debonding. Thus, a seam with a crenellation shape is particularly interesting.

[0061] Of course, it does not go beyond the scope of the invention if the seam produced has another shape.

[0062] The seam(s) may also be made by tufting. The seam(s) may also be made at least in part with invisible stitches. The seam(s) may also be made at least in part with one-sided stitches. It is of course possible to use several types of seams on the same fiber preform.

[0063] As illustrated in FIG. 8, the blade preform 10 is placed in an injection tool 300 which comprises a first shell 310 comprising in its center a first imprint 311 corresponding in part to the shape and the dimensions of the blade to be produced and a second shell 320 comprising in its center a second imprint 321 corresponding in part to the shape and dimensions of the blade to be produced.

[0064] Once the tool 300 is closed as illustrated in FIG. 9, the first and second impressions 311 and 321 respectively of the first and second shells 310 and 320 together define a molding cavity 301 having the shape of the blade to be produced and in which the preform 10 is held.

[0065] The fibrous part of the preform, here the shaped fibrous blank, is then densified, as illustrated in Figure 9. The densification of the fibrous part of the preform consists of filling its porosity with the material constituting the matrix. This densification is carried out in a manner known per se using the liquid process (LC). The liquid process consists of impregnating the preform with a liquid composition containing a precursor of the matrix material. The precursor is usually in the form of a polymer, such as a high-performance epoxy resin, possibly diluted in a solvent.

[0066] The transformation of the precursor into a matrix, namely its polymerization, is carried out by heat treatment, generally by heating the injection tooling, after elimination of any solvent and crosslinking of the polymer, the preform still being maintained in the molding cavity having a shape corresponding to that of the part to be produced. In the example described here, the injection tooling 300 further comprises a lower part 340 and an upper part 350 between which the first and second shells 310 and 320 are placed, the lower part 340 and the upper part 350 being equipped with heating means (not shown in FIG. 9).

[0067] In the case of the formation of a carbon or ceramic matrix, the heat treatment consists of pyrolyzing the precursor to transform the matrix into a carbon or ceramic matrix depending on the precursor used and the pyrolysis conditions. For example, liquid ceramic precursors, in particular SiC, can be resins of the polycarbosilane (PCS) or polytitanocarbosilane (PTCS) or polysilazane (PSZ) type, while liquid carbon precursors can be resins with a relatively high coke content, such as phenolic resins. Several consecutive cycles, from impregnation to heat treatment, can be carried out to achieve the desired degree of densification.

[0068] According to one aspect of the invention, the densification of the fiber preform can be carried out by the well-known transfer molding process known as RTM ("Resin Transfer Molding"). According to the RTM process, the fiber preform is placed in a mold having the external shape of the part to be produced. A thermosetting resin is injected into the internal space of the mold which includes the fiber preform. A pressure gradient is generally established in this internal space between the place where the resin is injected and the orifices for discharging the latter in order to control and optimize the impregnation of the preform by the resin.

[0069] As illustrated in Figure 9 and in accordance with the RTM method, a resin 380, for example a thermosetting resin, is injected via the injection port 313 of the first shell 310 into the molding cavity 301 occupied by the preform 10. Before injecting the resin 380, the molding cavity 301 is placed under vacuum, for example via the port 323 of the second shell 320 which is connected to a vacuum draw duct. This configuration allows the establishment of a pressure gradient between the lower part of the preform 10 where the resin is injected and the upper part of the preform located near the port 323. In this way, the resin 360 injected substantially at the level of the lower part of the preform will gradually impregnate the entire fibrous part of the preform by circulating therein to the evacuation port 323 through which the surplus is evacuated.Of course, the first and second shells 310 and 320 of the tooling 300 may respectively comprise several injection ports and several evacuation ports.

[0070] The resin used can be, for example, an epoxy resin with a temperature class of 180 °C (maximum temperature supported without loss of characteristics). Resins suitable for RTM processes are well known. They preferably have a low viscosity to facilitate their injection into the fibers. The choice of temperature class and / or the chemical nature of the resin is determined according to the thermomechanical stresses to which the resin must be subjected. subjected the part. Once the resin has been injected throughout the reinforcement, it is polymerized by heat treatment in accordance with the RTM process.

[0071] The injection of the resin into the fiber preform and its transformation into a matrix allows the densification or consolidation of the aerodynamic profile preform part 211 of the blade preform constituted by the dry fiber blank 100.

[0072] After injection and polymerization, a composite material part 1 having the shape of the blade to be produced is demolded. Finally, the composite material part can be trimmed to remove excess resin and machining operations can be carried out. A composite material part 1 is then obtained comprising a fibrous reinforcement densified by the matrix, said fibrous reinforcement comprising at least the fibrous preform 10.

[0073] In the example illustrated in the figures, the insert 40 is part of the final blade or vane. It is of course not outside the scope of the invention if one or more inserts are transient, i.e. removed during the manufacturing process of the blade or vane.

[0074] The composite material part 1 is then assembled at least with a leading edge reinforcing element 2 to obtain the desired blade or vane 3, as illustrated in FIG. 10. The reinforcing element 2 is attached to the leading edge of the vane. The reinforcing element 2 is attached so as to cover at least part of the seam(s). In particular, the reinforcing element 2 may at least partially cover the second seam(s) 62. The reinforcing element 2 may completely cover the second seam(s) 62. The reinforcing element 2 may conventionally be made of metal. The reinforcing element 2 may cover the entire leading edge of the vane.

Claims

Claims

1. Method for manufacturing a turbomachine propeller blade or vane (3), the method comprising: - producing a fibrous blank (100) by three-dimensional weaving of fibers (101, 102), said blank (100) comprising a separation (103) separating a first skin (110) from a second skin (120) of the fibrous blank (100) so as to form an internal housing (103a) between the skins (110, 120), the separation (103) extending at least partly from an edge (100a) of the fibrous blank (100) intended to form the leading edge of the blade or vane (3), - the introduction of an insert (40) into the internal housing (103a) of the fiber blank (100) so as to form a fiber preform (10), the insert (40) filling only a part of the internal housing (103a) of the blank (100), - holding the fiber preform (10) in a molding cavity of an injection tool (300) having the shape of the blade or propeller blade (3) to be manufactured, - injecting a resin into the molding cavity containing the fiber preform (10) and transforming the resin into a matrix by heat treatment to obtain a composite material part (1) having the shape of the blade or vane (3) to be obtained and comprising a leading edge, and - adding a reinforcing element (2) attached to the leading edge, the method being characterized in that it comprises an operation of sewing the first skin (110) to the second skin (120) by sewing threads (6) in at least one zone without insert (104b, 104c), said zone (104b) comprising the edge (100a) intended to form the leading edge of the blade or vane (3) to be obtained, the sewing operation being carried out after the introduction of the insert (40) and before the injection of the resin, and in that the reinforcing element (2) at least partially covers the seam(s) (61, 62) produced.

2. A manufacturing method according to claim 1, wherein the stitching threads (6) follow a notch-shaped path.

3. A manufacturing method according to claim 1 or 2, wherein the seam(s) are made at least partly by tufting.

4. Manufacturing method according to any one of claims 1 to 3, in which the seam(s) are made at least partly with invisible stitches.

5. Manufacturing method according to any one of claims 1 to 4, in which the seam(s) are made at least in part with one-sided stitches.

6. A manufacturing method according to any one of claims 1 to 5, wherein the delinking also extends from an edge of the fibrous blank intended to form the trailing edge of the blade or vane, the area devoid of insert comprising the edge intended to form the trailing edge of the blade or vane to be obtained so that the first skin is sewn to the second skin by the stitching threads at this edge intended to form the trailing edge.

7. Manufacturing method according to any one of claims 1 to 6, wherein the fibrous blank (100) extends in a longitudinal direction corresponding to the span direction of the blade or vane (3) to be manufactured between a lower edge (100c) and an upper edge corresponding to the head of the blade or vane (3) to be manufactured, the delinking (103) extending from the lower edge (100c) of the fibrous blank (100).

8. A manufacturing method according to any one of claims 1 to 7, wherein at least one of the seams (62) extends along the edge (100a) intended to form the leading edge.

9. A manufacturing method according to claim 8, wherein all the seams extend along the edge intended to form the leading edge and are covered by the reinforcing element.

Images