METHOD FOR MANUFACTURING A PART MADE OF COMPOSITE MATERIAL AND PART THUS MANUFACTURED

Abstract

The invention relates to a method for manufacturing a part made of composite material from a preform (10) composed of a woven structure of reinforcing fibers comprising a first series of fibers (f1) extending in a first longitudinal direction and a second series of fibers (f2) extending in a second direction, the preform comprising two adjacent zones (10a, 10b) connected to each other by the longitudinal fibers. The woven structure comprises:-in the first series of fibers (f1), a portion of the reinforcing fibers which have a melting point lower than the melting point of a first composite matrix subsequently used for producing a first composite structure and / or-in the second series of fibers (f2), at least a portion of the reinforcing fibers which have a melting point lower than the melting point of the first composite matrix subsequently used for producing the first composite structure.Figure for abstract: Fig. 1B.

Description

Title of the invention: METHOD FOR MANUFACTURING A PART MADE OF COMPOSITE MATERIAL AND PART THUS MANUFACTURED Technical field

[0001] The present disclosure relates to a method of manufacturing a part made of composite material and a part thus manufactured.

[0002] The invention applies in particular to aeronautical and space parts, in particular in turbomachines, in particular aeronautical. Prior art

[0003] In aeronautics, the parts which are used, for example in turbojets and, in particular, rotor blades, are subject to severe operational constraints.

[0004] More and more aeronautical parts are made from composite materials due to the very good weight / stiffness compromise that these materials can achieve.

[0005] Patent application FR 3 124 422 A1 discloses a method which makes it possible to simply and efficiently manufacture a part made of composite material having several zones which can be subjected, during use of the part, to specific environments, in particular represented by stress or temperature fields specific from one zone to another. According to this method, for example, two composite structures are produced on two adjacent zones of a preform having reinforcing fibers which extend in these two zones, starting with the zone where the production of the composite structure involves the highest temperature, for example a composite structure made of metallic material (CMM). The composite structure is then produced which involves a temperature lower than the first temperature, for example a composite structure made of organic material (CMO).

[0006] In this patent application, for example, a turbomachine rotor blade is manufactured.

[0007] Although this method is satisfactory, the inventors have observed the following phenomenon: when the blade root is made of a metallic composite material and the blade is made of an organic composite material, the metallic composite structure of the root is generally produced by low-pressure casting because high-pressure casting cannot be used due to the specificities of the method. In particular, it is impossible to achieve perfect sealing at the levels of the long fibers which would protrude from the mold. A “high-pressure” injection restricted to a zone local long fibers is therefore not possible as it stands.

[0008] However, when performing low-pressure metal casting, the inventors have noticed that the metal matrix introduced into the mold does not allow the reinforcing fibers of the preform to be sufficiently impregnated, and this has the consequence that the mechanical properties for the resulting part are not optimal. In particular, the mechanical permissible values, for example the first damage, or the tensile moduli, for example the longitudinal tensile modulus, are partly dependent on the fiber / resin contact surface at the mesoscopic scale. If this surface is considerably reduced, then the permissible values ​​and moduli are necessarily impacted.

[0009] In view of the above, it would therefore be useful to be able to improve the manufacturing process described above in order to improve the mechanical properties of the part thus manufactured. Statement of the invention

[0010] The subject of the invention is thus a method for manufacturing a part made of composite material from a preform composed of a woven structure of reinforcing fibers, the woven structure comprising a first series of reinforcing fibers f1 which extend in a first longitudinal direction and a second series of reinforcing fibers f2 which extend in a second direction, the preform comprising at least two adjacent zones which are such that the reinforcing fibers of the first series of reinforcing fibers f1 have a length which extends in said at least two adjacent zones so as to ensure continuity of the reinforcing fibers from one zone to the other in the first longitudinal direction, characterized in that the woven structure of reinforcing fibers f1, f2 comprises, with a view to subsequently producing in a first of said at least two adjacent zones of the preform,a first composite structure from the reinforcing fibers of the first zone and the introduction, into this first zone, of a first composite matrix:, -in the first series of reinforcing fibers fl, a portion of the reinforcing fibers which have a melting point lower than the melting point of the first composite matrix subsequently used for the production of the first composite structure and / or -in the second series of reinforcing fibers f2, at least a portion of the reinforcing fibers which have a melting point lower than the melting point of the first composite matrix subsequently used for the production of the first composite structure.

[0011] The use of reinforcing fibers having a melting point lower than the melting point of the first composite matrix subsequently used for the production of the first composite structure allows, during the subsequent introduction of this matrix, to make these reinforcing fibers disappear, which will be physically degraded by the operating temperature conditions used (injection of matrix / liquid resin at this temperature). Thus, the liquid matrix that is introduced occupies the space left free in the first zone by the reinforcing fibers which melt on contact with the hot matrix, which makes it possible to obtain better impregnation of the remaining reinforcing fibers by the matrix (more intimate mixture which binds the matrix more closely to the fibers) and therefore better mechanical strength of the composite structure thus produced. The injected matrix thus replaces the space which was previously occupied by the fibers. Generally speaking, the volume rate of fibers in the manufactured part can vary between 25% and 75%. It should be noted that the remaining reinforcing fibers are made from materials having a melting point higher than that of the composite matrix used.

[0012] This process therefore makes it possible to manufacture parts from composite material having improved mechanical behavior, in particular which have a higher tensile modulus.

[0013] According to other possible characteristics: -the portion of the reinforcing fibers of the first series of reinforcing fibers fl is less than 50% of the total of the reinforcing fibers of the first series of reinforcing fibers fl; -the reinforcing fibers the first series of reinforcing fibers fl which have a melting point lower than the melting point of the first composite matrix used subsequently for the production of the first composite structure are chosen from flax fibers, hemp fibers, bamboo fibers - the reinforcing fibers the second series of reinforcing fibers f2 which have a melting point lower than the melting point of the first composite matrix used subsequently for the production of the first composite structure are chosen from flax fibers, hemp fibers, bamboo fibers; -the method comprises producing successive distinct composite structures for each of said at least two adjacent zones of the preform, by first producing the first composite structure of the first zone, then a second composite structure of a second zone adjacent to this first zone, and so on for each possible additional adjacent zone, each distinct composite structure being produced, on the one hand, by introducing a composite matrix into a zone of the preform, such as the first composite matrix into the first zone of the preform and, on the other hand, by applying to this zone operating conditions, in particular temperature, suitable for producing the composite structure from the reinforcing fibers of the zone and the composite matrix introduced,the different zones of said at least two adjacent zones of the preform being treated in an order which corresponds to the decreasing order of the temperatures used in the, operating conditions applied to the production of distinct composite structures; - the preform comprises two distinct adjacent zones, the matrix introduced into each zone being different from one zone to the other and chosen from an organic matrix, a metallic matrix, a ceramic matrix; - the matrix introduced into the first zone of the preform is a metal matrix, the matrix introduced into the second zone being chosen from an organic matrix and a ceramic matrix; - the reinforcing fibers include carbon fibers, silicon carbide fibers, glass fibers, boron fibers, alumina fibers; - the preform is formed from a single piece.

[0014] The invention also relates to a part made of composite material which comprises several distinct composite structures produced by the method briefly described above and which are intimately linked to each other by the common reinforcing fibers.

[0015] According to other possible characteristics: -the composite material part is a turbomachine rotor blade (fan blade); -the rotor blade comprises, on the one hand, a blade root forming a composite structure made from a metal matrix (CMM) and, on the other hand, a blade forming a composite structure made from an organic matrix (CMO); -the part is a turboprop propeller. The invention also relates to a turbomachine rotor (fan) comprising a plurality of composite material parts (rotor blades) as briefly described above.

[0016] The invention also relates to a turbomachine comprising a turbomachine rotor as briefly described above. Brief description of the drawings

[0017] Other characteristics and advantages of the subject of the present disclosure will emerge from the following description of embodiments, given as non-limiting examples, with reference to the appended figures.

[0018] [Fig.lA] [Fig.lA] is a schematic representation of a first step of producing a fan blade preform according to an embodiment of a method according to the invention;

[0019] [Fig.lB] [Fig.lB] illustrates in more detail the woven structure of [Fig.lA];

[0020] [Fig. IC] [Fig. IC] illustrates a following step of placing the preform of figures 1A and 1B in a mold according to the embodiment of the method;

[0021] [Fig.lD] [Fig.lD] illustrates a next step of the embodiment of the method during which a metallic composite matrix is ​​introduced into the mold of [Fig.lC];

[0022] [Fig.lE] [Fig.lE] illustrates a step of producing a first metallic composite structure according to the embodiment of the method;

[0023] [Fig.lF] [Fig.lF] illustrates a subsequent step of the embodiment of the method during which the composite structure undergoes a mechanical finishing treatment;

[0024] [Fig.lG] [Fig.lG] illustrates a subsequent step of placing the partially processed preform of [Fig.lF] into a mold according to the embodiment of the method;

[0025] [Fig.lH] [Fig.lH] is a schematic view illustrating the introduction of an organic composite matrix into the mold of [Fig.lG];

[0026] [Fig. II] [Fig. II] illustrates the production of the second composite structure organic according to the method of carrying out the process in order to obtain the final composite part;

[0027] [Fig.2] [Fig.2] is a schematic representation of a turbomachine incorporating a fan whose blades have been manufactured according to the embodiment of the method whose steps are illustrated in the preceding figures;

[0028] [Fig.3] [Fig.3] illustrates one of the blades of [Fig.2]. Detailed description

[0029] The following detailed description relates to an embodiment of a method for manufacturing a fan blade made of composite material for a turbomachine for an aircraft.

[0030] However, the manufacturing method according to the invention applies to the manufacturing of other parts made of composite material for aeronautics and space for which distinct zones of the same part must meet functional specifications that differ from one zone to another when the part is put into operation.

[0031] Figures 1A-I illustrate different possible steps of the method for manufacturing a composite material blade mentioned above. It will be noted that the following description also applies to the manufacture of any other composite material part having at least two parts or zones to be transformed into composite zones independently of each other, using either the same composite matrices or one or more other composite matrices.

[0032] [Fig.lA] illustrates very schematically the manufacture of a preform or blank 10 of a fan rotor blade. This preform is composed of a woven structure of intersecting reinforcing fibers f1, f2 which form a two-dimensional or three-dimensional mesh.

[0033] For example, the preform can be produced in a known manner using 3D weaving or in another known manner, for example in a weave which forms a weave structure such as an interlock, multi-plain, multi-satin or multi-twill structure.

[0034] As shown schematically in [Fig. 1B], in more detail than in [Fig. 1A], the woven structure comprises, more particularly, a first series of reinforcing fibers f1 (long fibers) which extend in a first longitudinal direction, here denoted Z, which corresponds to the direction in which the height dimension of the future blade extends. The woven structure also comprises a second series of reinforcing fibers f2 (transverse fibers) which extend in a second direction, denoted X, and which is generally secant to the first direction and, here, which is more particularly perpendicular to the first direction Z. This direction corresponds to the direction in which the future blade extends transversely, between the leading edge and the trailing edge thereof (width or chord of the blade). It will be noted that the long fibers f1 are called warp fibers and the transverse fibers f2 are called weft fibers.

[0035] The preform 10 comprises at least two adjacent or contiguous (spatially) parts or zones, here two in number denoted 10a, 10b, which are such that the reinforcing fibers of the first series of reinforcing fibers f1 have a length (along Z) which extends in the two adjacent zones so as to ensure continuity of the reinforcing fibers from one zone to the other along the first longitudinal direction.

[0036] The zone 10a, called lower, forms the root of the future blade and the zone 10b, called upper, forms the upper part or blade of the future blade. Each of these parts is subjected to very different stresses when the blade is used on a fan rotor. In particular, the blade root may be subjected to higher thermal stresses than the upper part further from the rotor, to more restrictive assembly stresses than the upper part (for example due to machining, drilling, etc. requirements) or to specific mechanical stresses (for example due to the existence of matting pressures). Furthermore, it is more particularly sought to achieve a weight saving on the upper part of the blade due to the high rotation speeds. The two parts 10a and 10b described above are geometrically arranged adjacent or contiguous to each other.In this respect, it will be noted that the same long reinforcing fibers fl extend here continuously in the two distinct parts or zones 10a and 10b of the preform so that it is not possible to physically separate the two parts from each other without damaging one and / or the other of them. The presence of the reinforcing fibers common to the two zones gives the preform thus formed sufficient mechanical strength so that the subsequent steps of manufacturing the composite structures on each of these zones can be carried out without affecting the preform, and in particular without damaging it.

[0037] Due to the environmental constraints specific to each of the parts or areas described above, each of them will be subjected to a different processing method from one area to another in order to obtain a composite material structure that differs from one area to another. Each distinct composite structure will thus make it possible to meet locally different functional requirements.

[0038] As shown in [Fig.lB], in this embodiment, the first series of long reinforcing fibers fl is formed of a first part of these reinforcing fibers denoted fl.l (first type of fibers) and a second part fl.2 (second type of fibers).

[0039] The fibers fl.1 of the first part are selected to have a melting point lower than the melting point of the composite matrix (first) which will be used later for the production of the composite structure of the first part 10a (foot) of the preform (first composite structure). The fibers fl.2, for their part, have a melting point higher than the melting point of the first composite matrix. Thus, when the first composite matrix is ​​introduced into the first zone 10a, the liquid material of the resin will impregnate the zone and will be distributed between the different fibers. In contact with this material, the fibers of the first type fl.1 will melt, which will allow this material to fill the spaces occupied by these fibers and therefore to obtain a better impregnation of the remaining fibers (second type fl.2) by the material.By solidifying, the composite structure thus obtained will offer better mechanical strength, particularly in traction, since the matrix is ​​more intimately mixed with the fibers and surrounds them more homogeneously than before. It should be noted that the portions of fl.l fibers remaining in the second zone are not "melted" by the resin. These portions can possibly be removed / deleted between the injection of the two resins (manually or by heating for example) or left in place if the impact on the new material thus created in the second zone has mechanical properties which remain compatible with the stresses of the part.

[0040] As the preform 10 is here a preform of a rotating part (blade or propeller), the fibers fl.1 are positioned preferentially in the portion of the zone 10a which is close to the axis of rotation, symbolized here by the axis A. On the other hand, the portions further from the axis A are generally formed of fibers of the second type fl.2. It will be noted that the portion of the zone 10a close to the axis of rotation A may also comprise fibers of the second type fl.2. If the preform 10 is a preform of a static part, such as a turbomachine stator part, all the portions of the zone of the preform may contain fibers of the first type fl.1 (replaceable fibers).

[0041] Generally, the reinforcing fibers of the first type fl.l are less in quantity than 50% of the total of the reinforcing fibers of the first series of fibers of reinforcement (fl.l and fl.2). Indeed, as it is the long fibers fl which ensure the geometric continuity between the two adjacent zones 10a, 10b and the stiffness of the preform, it is important to keep a significant part of them (at least 50%) in the preform after production of the first composite structure.

[0042] More particularly, the reinforcing fibers of the first type fl.1 are less in quantity than 25% (one fiber out of four) of the total of the reinforcing fibers of the first series of reinforcing fibers (fl.1 and fl.2). This makes it possible to improve the overall mechanical strength of the two zones between them along the longitudinal dimension.

[0043] In an exemplary embodiment not shown, the reinforcing fibers of the first zone 10a only comprise fibers of the second type fl.2 which will therefore not be degraded during the manufacture of the composite structure, as the fibers fl.1 would have been.

[0044] Furthermore, the second series of transverse reinforcing fibers f2 can be formed from a first part of these reinforcing fibers denoted f2.1 (first type of fibers) and a second part f2.2 (second type of fibers).

[0045] The fibers f2.1 of the first part 10a are selected to have a melting point lower than the melting point of the first composite matrix which will be used later for the production of the composite structure of the first part 10a (foot) of the preform (first composite structure). The fibers f2.2, for their part, have a melting point higher than the melting point of the first composite matrix. Thus, when the first composite matrix is ​​introduced into the first zone 10a, the liquid material of the resin will impregnate the zone and will be distributed between the different fibers. Upon contact with this material, the fibers of the first type f2.1 will melt, which will allow this material to fill the spaces occupied by these fibers and therefore to obtain a better impregnation of the remaining fibers (second type f2.2) by the material.By solidifying, the composite structure thus obtained will offer better mechanical strength, particularly in traction, to the extent that the matrix is ​​more intimately mixed with the fibers and surrounds them more homogeneously than before.

[0046] The distribution of the different fibers f2.1 and f2.2 in the first zone 10a is variable and can take different forms. For example, the fibers f2.1 and f2.2 can be arranged alternately or differently according to the needs and in relative proportions which also differ according to the needs.

[0047] It will be noted that here, unlike the fibers f1, there is no minimum quantity of fibers of the second type f2.2, nor a maximum quantity of fibers of the first type f2.1 to be respected. Thus, in an extreme case, all the fibers f2 of the first zone 10a can be of the first type f2.1 and therefore be replaced by the liquid matrix during the manufacture of the first composite structure. This extreme case can occur in the case where there is a specific need for mechanical characteristics in the chain direction.

[0048] Conversely, in an opposite extreme case, all the fibers f2 of the first zone 10a are of the second type f2.2 and are therefore retained during the manufacture of the first composite structure. This extreme case can occur in the case where there is a specific need for a mechanical characteristic in the weft direction.

[0049] More generally, the fibers f2.1 of the first part 10a may represent in quantity between 0% and 100% of the totality of the reinforcing fibers of the second series of reinforcing fibers (f2.1 and f2.2), preferably between 50% (one fiber out of two) and 100%.

[0050] Thus, depending on the different possible ratios that are applied during the weaving step of the structure forming the preform, the fiber volume ratio (TVF) that is obtained in the transformed preform (after production of the composite structures) can vary between a value substantially equal to the initial TVF (in the case where very few replaceable fibers are woven) and 50% of the initial TVF (in the case where 50% of replaceable fibers are inserted in the warp direction and 100% of replaceable fibers are inserted in the weft direction). This gives the part a very wide range of TVF and therefore of possible impregnation to meet the required stresses.

[0051] For example, the first type reinforcing fibers of the first series and the second series of reinforcing fibers (f1.1, f2.1) are chosen from flax fibers, hemp fibers, bamboo fibers. Natural fibers generally degrade at around 350-400°C maximum but the temperature can be lower depending on the fibers used.

[0052] It will be noted that for the sake of simplification of the weaving step, the same fibers will be used for both sets of fibers. However, depending on the needs, different fibers can be selected for the two sets of fibers, for example to optimize the weaving. Generally, the warp fibers are constantly stretched while the weft fibers come from a single reel which is regularly cut to form the wefts. Thus, it would therefore be possible to have natural fibers with a high modulus in the warp direction to avoid damage to the fibers during weaving and, conversely, to have fibers that can be easily cut in the weft direction.

[0053] By way of example, the second type reinforcing fibers of the first series and of the second series of reinforcing fibers (f1.2, f2.2) may be carbon, silicon carbide, glass, boron or alumina fibers, or even a mixture of some of these fibers (e.g.: glass fibers and carbon fibers).

[0054] It will be noted that the reinforcing fibers of the second zone 10b comprise the same long reinforcing fibers fl as the first zone 10a, namely the mixture of fibers fl.1 and fl.2 of this zone (or only fibers fl.2 depending on the case) and generally comprise- rally only transverse reinforcing fibers of the second type f2.2. Indeed, it is not necessary to improve in this zone the impregnation of the fibers by the liquid matrix (better mechanical cohesion of the composite structure obtained). Typically, zone 10a can be made using a metal matrix with a melting point above 650°C (for example aluminum), while zone 10b can be made using an organic matrix (melting point of approximately 180°C). It should be noted that at this temperature it is not possible to make the natural fibers disappear.

[0055] However, in the case of two metal matrices (for example titanium for zone 10a and aluminum for zone 10b), it is possible to make natural fibers disappear in zone 10b and therefore to have, in this zone, replaceable fibers within the meaning of the invention.

[0056] The following steps 1C-1I illustrate very schematically, successively, the production of the first composite structure, on the first zone of the preform, here the lower zone 10a, using a first treatment method (here introduction of a first matrix in order to form a composite structure with a metal matrix) and the production of a second composite structure, on the second adjacent zone of the preform, here the upper zone 10b, using a second treatment method (here introduction of a second matrix in order to form a composite structure with an organic matrix).

[0057] Before carrying out these steps, the woven structure undergoes, for example, a suitable cutting step known per se.

[0058] [Fig. 1C] illustrates the vertical positioning of the preform 10 (as described with reference to FIGS. 1A and 1B) in a mold 12 with the first zone 10a of the preform arranged in the lower part of the mold, that is to say close to the bottom thereof.

[0059] [Fig. 1D] illustrates a step of introducing a liquid metal (introduction of a metal matrix) inside the mold so that the metal is in contact with the first zone 10a of the preform located at the bottom of the mold and can impregnate all of the reinforcing fibers f1, f2 constituting this first zone. The internal part of the mold with which the first zone 10a of the preform is in contact is shaped so as to give the desired shape to this zone (here intended to form the root of the blade).

[0060] The metal can, for example, be poured by gravity inside the mold (for example from a container 14) or injected at low pressure (for example of the order of a few MPa) into the latter by a known means.

[0061] In the embodiment described, the metal is for example aluminum and the temperature applied is substantially equal to the melting temperature of the matrix. metallic, here around 660°C for aluminum. Other metals are of course possible depending on the functional constraints that the first zone of the part must meet. For example, titanium can be used to form the metal matrix and the temperature applied is approximately equal to the melting temperature of the metal matrix, here around 1660°C for titanium.

[0062] During this step ([Fig.lD]), as already described above, the molten metal which is introduced into the mold containing the first zone 10a is distributed between the fibers fl, f2 of the first zone and melts the first type fibers fl.l and f2.1 while occupying, at the same time, the space left free by these fibers. The molten metal is also distributed around the other fibers fl.2 and f2.2 which it envelops. Due to the disappearance of the first type fibers fl.l and f2.1 the molten metal can insert itself more between the remaining fibers which are likely to move slightly under the action of the metal flow. In the end, a greater quantity of metal can impregnate the woven structure of the first zone, which will improve its cohesion and its overall strength after solidification.

[0063] During this step ([Fig.lD]), the second zone 10b of the preform is preserved from any treatment and, in particular, is not treated by the method which is used only for the treatment of the first part 10a.

[0064] [Fig. 1E] schematically illustrates and groups together the steps of cooling, then hardening of the assembly formed by the reinforcing fibers and the metal matrix introduced into the first zone 10a of the preform in order to obtain a metal-based composite structure for this zone. The first zone thus treated is represented by the reference 10a'. The second zone 10b which is located in the upper part of the mold 12 is still not treated and only comprises, for the moment, the reinforcing fibers of the preform illustrated in FIGS. 1A and 1B. The longitudinal reinforcing fibers fl (fl.1, fl.2) of the preform which extend along their length straddling the two zones 10a, 10b of the preform thus have, on the one hand, a first portion of their length located in the first zone 10a' which is now part of the first structure made of composite material (with regard to the fibers of the second type fl.2 of the zone because the fibers of the first type fl.l have disappeared during the step of [Fig.lD]) and, on the other hand, a second portion of their length located in the second zone 10b not yet treated. These second portions of longitudinal fibers are thus physically integral with the first zone via the first portions to which they are still linked (with regard to the fibers of the second type fl.2; the fibers of type fl.l of the second zone are for example still present in the latter). It will be noted that only a part of all the reinforcing fibers fl of the preform can extend from one zone to the other, while the remaining part of the reinforcing fibers of the preform may not. extend only in one or the other of these zones, insofar as a significant fraction of the reinforcing fibers extends both in one zone and in the other zone and therefore makes it possible to ensure physical continuity between these zones. Thus, the fibers fl.l of the preform may, in an exemplary embodiment not shown, extend only in the first zone.

[0065] [Fig. 1F] illustrates schematically and grouped together the steps of demolding, then deburring or machining, for example on a support 16 of the first composite structure 10a'.

[0066] [Fig. 1G] schematically illustrates the positioning of the second zone 10b of the preform not yet treated inside a second mold or container 18, leaving the first composite structure 10a' outside this mold. A peripheral seal system 20 may be provided at the junction between the two zones 10a' and 10b in order to hermetically close the mold 18 on the second zone 10b, thus forming an autoclave inside which a desired temperature (non-ambient temperature) can be applied in a controlled manner for the production of the composite structure.

[0067] The internal part of the mold 18 with which the second zone 10b of the preform is in contact is shaped so as to give the desired shape to this zone.

[0068] A system 22 for injecting a second matrix, here an epoxy resin, under pressure is implemented in order to inject a controlled quantity (volume) of resin under pressure into the mold 18 via an orifice 18a from a reservoir and, for example, a pumping device. By way of example, the known technique of resin transfer molding or RTM (known in English terminology as “Resin Transfer Molding”) can be used. The temperature of the epoxy resin is of the order of 150°C and the pressure in the mold is substantially equal to 10 bars.

[0069] It will be noted that the temperature used during this step is lower than that used for the production of the first composite structure on the first zone 10a. Indeed, the production of the composite structures in the reverse order to that described would not be possible because it would lead to a degradation of the first composite structure obtained.

[0070] The introduction of the resin inside the mold 18 makes it possible to impregnate or coat all of the reinforcing fibers not yet treated in the second zone 10b with this second composite matrix.

[0071] Once the resin has been completely injected into the mold, it is planned to let the assembly formed by the reinforcing fibers and the resin introduced into the second zone 10b (organic matrix) cool, then harden in order to obtain an organic-based composite structure for this zone. The second zone thus treated is represented by the reference 10b' in [Fig.II].

[0072] Steps of demolding, then deburring or machining of this second zone are then carried out in order to obtain the composite material part illustrated very schematically in [Fig. II] and which comprises the two adjacent composite structures of the fan blade 10' thus manufactured.

[0073] Everything described above applies generally, regardless of the processing method used to produce each composite structure, regardless of the part to be manufactured and the number of zones and, therefore, the number of composite structures to be manufactured.

[0074] [Fig. 2] illustrates an exemplary embodiment of a turbomachine (turboreactor) 30 (here shown shrouded although it may be unshrouded) comprising a fan 32 which incorporates fan blades 34 manufactured according to the method described above. It will be noted that the blades manufactured by the method described above may be blades of a rotor of a turbomachine which is not necessarily a fan.

[0075] [Fig. 3] illustrates an example of a fan blade 34 used in the fan 32 of [Fig. 2].

[0076] According to another embodiment, the method can be used to manufacture a part made of composite material comprising three distinct zones with heterogeneous functionalities.

[0077] For example, such a part may be a turboprop propeller.

[0078] The preform of such a propeller comprises three distinct zones, namely a first zone corresponding to the root of the propeller, a second zone corresponding to the leading edge of the propeller which is subjected to abrasive erosion and a third zone corresponding to the rest of the part which must be as light as possible. In such a preform, a portion of the reinforcing fibers of the first zone extends into the second zone adjacent to the first and another portion of the reinforcing fibers of the first zone extends into the third zone adjacent to the first and second. Thus, the first and second zones are spatially connected to each other by a portion of the reinforcing fibers and the first and third zones are spatially connected to each other by the other portion of the reinforcing fibers.

[0079] At least as regards the first and second zones of the preform, everything that has been described above in the context of the first embodiment applies here to enable better impregnation of the reinforcing fibers of the first zone by the resin and therefore better mechanical strength of the composite structure thus obtained.

[0080] In this example, the reinforcing fibers of the preform are made of silicon carbide (SiC). The first area of ​​the foot can be treated to produce a composite structure metal matrix, for example using an aluminum matrix. The second zone of the leading edge can be treated to produce a metal matrix composite structure, for example using a Ti-6Al-4V matrix. The third zone can be treated to produce an organic matrix composite (OMC) structure, for example using an epoxy matrix.

[0081] In this embodiment, again, the order of treatment of the zones is carried out according to the decreasing order of the temperatures applied during the production of each composite structure in order to treat the first zone by the method requiring the highest temperature and proceeding in an identical manner for the following zones. Thus, the second zone of the titanium leading edge will be treated first (temperature of 1660°C), then the first zone of the aluminum root (temperature of 660°C) and lastly the third zone for the rest of the blade in CMO (temperature of 150 / 200°C). The metal parts or zones are preferably treated by gravity by carrying out a casting operation of the metal matrices with the zone of interest located in the lower part. What has been described above for the first mode can also be applied here, possibly with some adjustments within the reach of a person skilled in the art.

[0082] The method can be used to manufacture a composite part with a greater number of heterogeneous areas to be treated than the numbers envisaged above.

[0083] Although the present description refers to specific exemplary embodiments, modifications may be made to these examples without departing from the general scope of the invention as defined by the claims. Furthermore, individual features of the various embodiments illustrated or mentioned may be combined in additional embodiments. Therefore, the description and drawings should be considered in an illustrative rather than restrictive sense.

Claims

Claims

1. A method of manufacturing a part made of composite material from a preform (10) composed of a woven structure of reinforcing fibers (fl, f2), the woven structure comprising a first series of reinforcing fibers (fl) which extend in a first longitudinal direction and a second series of reinforcing fibers (f2) which extend in a second direction, the preform comprising at least two adjacent zones (10a, 10b) which are such that the reinforcing fibers of the first series of reinforcing fibers (fl) have a length which extends in said at least two adjacent zones so as to ensure continuity of the reinforcing fibers from one zone to the other in the first longitudinal direction, characterized in that the woven structure of reinforcing fibers (fl, f2) comprises, with a view to subsequently producing in a first of said at least two adjacent zones of the preform,a first composite structure from the reinforcing fibers of the first zone and the introduction, into this first zone, of a first composite matrix: -in the first series of reinforcing fibers (fl), a portion of the reinforcing fibers (fl.l) which have a melting point lower than the melting point of the first composite matrix subsequently used for the production of the first composite structure and / or -in the second series of reinforcing fibers (f2), at least a portion of the reinforcing fibers (f2.1) which have a melting point lower than the melting point of the first composite matrix subsequently used for the production of the first composite structure.,

2. Manufacturing method according to claim 1, characterized in that the part of the reinforcing fibers of the first series of reinforcing fibers (fl) is less than 50% of the total of the reinforcing fibers of the first series of reinforcing fibers (fl).

3. Manufacturing method according to claim 1 or 2, characterized in that the reinforcing fibers, the first series of reinforcing fibers (fl) which have a melting point lower than the melting point of the first composite matrix subsequently used for the production of the first composite structure, are chosen from flax fibers, hemp fibers, bamboo fibers.

4. Manufacturing method according to one of claims 1 to 3, characterized in that the reinforcing fibers the second series of reinforcing fibers (f2) which have a melting point lower than the melting point of the first composite matrix subsequently used for the production of the first composite structure are chosen from flax fibers, hemp fibers, bamboo fibers.

5. Manufacturing method according to one of claims 1 to 4, characterized in that the method comprises the production of successive distinct composite structures for each of said at least two adjacent zones of the preform, by first producing the first composite structure (10a') of the first (10a) zone, then a second composite structure (10b') of a second zone (10b) adjacent to this first zone, and so on for each possible additional adjacent zone, each distinct composite structure being produced, on the one hand, by introducing a composite matrix into a zone of the preform, such as the first composite matrix into the first zone of the preform and, on the other hand, by applying to this zone operating conditions, in particular temperature, suitable for producing the composite structure from the reinforcing fibers of the zone and the composite matrix introduced,the different zones of said at least two adjacent zones of the preform being treated in an order which corresponds to the decreasing order of the temperatures used in the operating conditions applied to the production of the distinct composite structures.,

6. Manufacturing method according to one of claims 1 to 5, characterized in that the preform (10) comprises two distinct adjacent zones (10a, 10b), the matrix introduced into each zone being different from one zone to the other and chosen from an organic matrix, a metallic matrix, a ceramic matrix.

7. Part made of composite material, characterized in that it comprises several distinct composite structures produced by the method according to one of the preceding claims.

8. Composite material part according to the preceding claim, characterized in that the part is a turbomachine rotor blade.

9. Composite material part according to claim 7, characterized in that the part is a turboprop propeller.

10. Turbomachine rotor, characterized in that it comprises a plurality of parts made of composite material according to claim 7 or 8.

11. Turbomachine comprising a turbomachine rotor according to the preceding claim.

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