METHOD FOR MANUFACTURED A PART FROM COMPOSITE MATERIAL AND THE PART THUS MANUFACTURED

Abstract

The invention relates to a method for manufacturing a composite part from a preform comprising reinforcing fibers (f1) extending in one direction into two adjacent zones, the method comprising: - the application of tensile stresses on reinforcing fibers (f1) in the direction, - the introduction of a metallic composite matrix into a first zone (10a) comprising stretched reinforcing fibers and the application to this zone of operating conditions specific to the creation of a first composite structure from the fibers of the zone and the introduced matrix, - after solidification of the first composite structure, the release of the applied tensile stresses, - the introduction of a composite matrix into the second adjacent zone (10b) and the application to this second zone of operating conditions, in particular of temperature and pressure,specific to the creation of a second composite structure from the fibers of the second zone and the introduced matrix. Figure for the abbreviation: Fig. 1D,

Description

Title of the invention: METHOD FOR MANUFACTURED A PART FROM COMPOSITE MATERIAL AND THE PART THUS MANUFACTURED technical field

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

[0002] The invention applies in particular to aeronautical and space parts, especially in turbomachinery, particularly aeronautical. Previous technique

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

[0004] More and more aeronautical parts are being made from composite materials because of the very good weight / stiffness compromise that these materials make it possible to achieve.

[0005] The choice of a composite material is generally made according to the expected operating temperatures. For an aeronautical part, the choice may, for example, be based on the use of an Organic Matrix Composite (OMC), a Metallic Matrix Composite (MMC) or a Ceramic Matrix Composite (CMC).

[0006] However, a problem may arise when the part has to be adapted to a field of stresses or temperatures which is likely to vary spatially and / or temporally, significantly, during the use of the part.

[0007] To accommodate such adaptation, the part can be made in several parts, each adapted to a specific stress / temperature range, and then assembled to obtain the final part. However, the assembly of the different parts can prove critical, even very complex to implement, and relatively costly.

[0008] In view of the above, it would therefore be useful to be able to easily produce a composite part in which certain areas can be subjected, during the use of the part, to specific environments, in particular represented by specific stress and / or temperature fields from one area to another. Description of the invention

[0009] The invention thus relates to a method for manufacturing a part made of composite material from a preform comprising reinforcing fibers extending in at least one direction and comprising several zones, characterized in that the the preform comprises at least two adjacent zones such that at least some of the reinforcing fibers of the preform have a length extending into said at least two adjacent zones, along said at least one direction, so as to ensure continuity of the reinforcing fibers from one zone to the other, the process comprising the following steps: -application of tensile stresses on a set of reinforcing fibers along said at least one direction, called the stress direction, -introduction of a metallic composite matrix into a first of said at least two adjacent zones which comprise stretched reinforcing fibers and application to this first zone of operating conditions, in particular of temperature and pressure, specific to the realization of a first composite structure from the reinforcing fibers of the first zone and the metallic composite matrix introduced into this first zone, -after solidification of the first composite structure, release of the tensile stresses applied to the entire reinforcing fiber assembly along the direction of stress application, - introduction of a composite matrix into a second of said at least two adjacent zones and application to this second zone of operating conditions, in particular of temperature and pressure, specific to the realization of a second composite structure from the reinforcing fibers of the second zone and the composite matrix introduced into this second zone.

[0010] In general, this process allows for the manufacture of composite material parts in a particularly simple and efficient manner, since the part thus manufactured does not result from the assembly of several parts that would have been manufactured separately beforehand. The process described above makes it possible to treat adjacent or contiguous (two by two) areas of the same preform separately (spatially and temporally), insofar as these adjacent areas share reinforcing fibers of the preform that physically extend into each of these areas and connect one area to the other. These reinforcing fibers thus ensure spatial / geometric continuity between the treated areas within which they extend, so that the preform is formed as a single unit and not in several parts.Each of these zones can thus undergo a treatment specific to it in order to create a specific composite material structure, distinct from one zone to another. The specific treatment is a treatment or a treatment method (type of composite matrix used, operating conditions, in particular temperature, pressure, specific to the creation of a given composite) which aims to create a composite structure in a zone called the application zone, while the zone adjacent to this application zone, in the sense defined previously (i.e. the . The area that is spatially linked to the application area via reinforcing fibers is not treated during this time (it may have already been treated or will be treated later). The adjacent area is, for example, protected or isolated from the application area (area being treated). This process thus makes it possible to produce a composite part with distinct composite structures corresponding to distinct zones or geometric portions of the part that meet varying usage, environmental, or interface constraints from one zone to another (these different constraints prevent the part from being made from a single composite material, which could not simultaneously meet such specifications).

[0011] More specifically, the first treated area of ​​the preform is intended to form a metallic composite structure in which reinforcing fibers have been previously stretched to create a pre-stressed zone in the finished composite part. This pre-stressed zone gives the part better fatigue resistance than a part whose corresponding area has a metallic composite structure in which the reinforcing fibers have not been subjected to tension before the formation of the composite structure. Once the metallic composite structure has been thus formed, one or more other composite structures can be created on a second adjacent area of ​​the preform by applying operating conditions, particularly temperature and pressure, to this area, specifically designed to create a second composite structure from the reinforcing fibers of the second area and the composite matrix introduced into this second area.The process described above can be repeated with a third area, whether or not it is adjacent to the first area.

[0012] According to other possible characteristics: -the application of tensile stresses on the entire set of reinforcing fibers along the direction of stress application is carried out at the first ends of the reinforcing fibers of the entire set of reinforcing fibers, while the second opposite ends of the reinforcing fibers of the entire set of reinforcing fibers are held in a fixed position; Prior to applying tensile stresses to the entire reinforcing fiber assembly along the direction of stress application, a first portion of the metallic composite matrix is ​​introduced into the first zone, which contains the opposite ends of the reinforcing fibers. Operating conditions, particularly temperature and pressure, are applied to this first zone to create an initial incomplete composite structure from the reinforcing fibers of the first zone and the first portion of the metallic composite matrix introduced into this zone. The first complete composite structure is then created after the application of tensile stresses. introducing a second part of metallic composite matrix into the first zone and applying operating conditions, in particular of temperature and pressure, specific to the realization of the first complete composite structure; -the applied tensile stresses are dimensioned so that, in the composite material part thus manufactured, the part of the part corresponding to the first zone is pre-stressed in compression at stress values ​​between 20 and 80MPa; -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 preform comprises three distinct zones adjacent in pairs, the matrix introduced into each zone being chosen (different or not from one zone to another) from among an organic matrix, a metallic matrix, a ceramic matrix; -each of the three distinct zones is adjacent to the other two zones; -Reinforcing fibers include carbon fibers, silicon carbide fibers, glass fibers, boron fibers, alumina fibers; -the preform is formed in one piece.

[0013] The invention also relates to a part made of composite material which comprises several distinct composite structures made by the process briefly described above and which are intimately linked to each other by common reinforcing fibers.

[0014] According to other possible characteristics: -the separate composite structures are intended to be subjected each to a distinct field of mechanical stresses and / or temperatures from one area to another; -the part made of composite material is a turbomachine rotor blade (fan blade); alternatively, the part made of composite material is a turbomachine stator blade such as a straightening blade; -the rotor blade comprises, on the one hand, a blade root forming a composite structure made from a metallic matrix (CMM) and corresponding to the first zone of the preform and, on the other hand, a blade forming a composite structure made from an organic matrix (CMO); -the part is a turboprop propeller.

[0015] The invention also relates to a turbomachine rotor (blower) 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 features and advantages of the subject matter of this presentation will become apparent from the following description of embodiments, given by way of non-limiting examples, with reference to the attached figures.

[0018] [Fig.1A] The [Fig.1A] is a schematic representation of a first step in the realization of a blower blade preform according to an embodiment of a process according to the invention;

[0019] [Fig. IB] The [Fig. IB] is a more detailed representation of the preform of the [Fig. IA];

[0020] [Fig.lC] The [Fig.lC] illustrates a step during which the lower ends of the reinforcing fibers are held in a fixed position;

[0021] [Fig.1D] Fig.1D illustrates a step in which the upper ends of the reinforcing fibers are stretched;

[0022] [Fig.1E] Fig.1E illustrates a step during which a metallic composite structure is produced in the first zone;

[0023] [Fig.1F] [Fig.1F] illustrates a subsequent step of placing the preform of [Fig.1A] in a mold according to the embodiment of the process;

[0024] [Fig.1G] The [Fig.1G] illustrates a subsequent step in the embodiment of the process in which a metallic composite matrix is ​​introduced into the mold of the [Fig.1F];

[0025] [Fig.1H] The [Fig.1H] illustrates an optional step of partial metal casting on the first area of ​​the preform;

[0026] [Fig. II] [Fig. II] illustrates a subsequent step of placing the partially treated preform of [Fig. II] in a mold according to the embodiment of the process;

[0027] [Fig.U] The [Fig.U] is a schematic view illustrating the introduction of an organic composite matrix into the mold of the [Fig. II];

[0028] [Fig. 1K] The [Fig. 1K] illustrates the realization of the second organic composite structure according to the embodiment of the process in order to obtain the final composite part;

[0029] [Fig.2] The [Fig.2] is a schematic representation of a turbomachine incorporating a blower whose blades have been manufactured according to the embodiment of the process whose steps are illustrated in the preceding figures;

[0030] [Fig.3] The [Fig.3] illustrates one of the sails of the [Fig.2]. Detailed description

[0031] The following detailed description relates to an embodiment of a method for manufacturing a blower blade made of composite material for a turbomachine for a aircraft.

[0032] However, the manufacturing process according to the invention applies to the manufacture of other composite material parts for aeronautics and space for which distinct areas of the same part must meet different functional specifications from one area to another when the part is put into operation.

[0033] Figures 1A-K illustrate various possible steps in the manufacturing process for a composite material blade mentioned above. It should be noted that the following description also applies to the manufacture of any other composite material part having at least two parts or areas to be transformed into composite areas independently of each other, using a metallic composite matrix for the first area.

[0034] Figure 1A schematically illustrates the fabrication of a preform 10 of a blower blade. This preform is composed of reinforcing fibers, for example carbon fibers, which form a two- or three-dimensional mesh or structure of interwoven fibers. The fabrication of such a preform or blank from reinforcing fibers is widely known to those skilled in the art. For example, the preform can be produced using a known 3D weaving technique.

[0035] In [Fig. 1A], the reinforcing fibers are represented as an interlacing of first fibers fl extending in a first direction (in the so-called "warp direction") and second fibers f2 (in the so-called "weft direction") extending in a second direction, here perpendicular to the first direction. This designation "warp" and "weft" is borrowed from the concept of warp yarns and weft yarns used in the weaving of composite preforms.

[0036] In the present embodiment, the first fibers are called longitudinal fibers or warp yarns and are intended to extend along the longitudinal dimension or height of the blank (corresponding to the height of the blade), while the second fibers are called transverse fibers or weft yarns and are intended to extend along the transverse dimension or width of the blank (this dimension extends along the chord of the blade, that is to say between the leading edge and the trailing edge of the latter).

[0037] The preform 10 comprises two adjacent or contiguous (spatially) parts or zones, namely a part or zone 10a, referred to as the lower part, which forms the root of the future blade, and a part or zone 10b, referred to as the upper part, which 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, which is further from the rotor, to more demanding assembly stresses than the upper part (for example, due to machining, drilling requirements, etc.), or to mechanical stresses. specific mechanical factors (for example, due to the presence of swaging pressures) are involved. Furthermore, a particular aim is to achieve a mass reduction in the upper part of the blade due to the high rotational speeds. The two parts 10a and 10b described above are arranged geometrically adjacent to each other. In this regard, it should be noted that the same reinforcing fibers fl extend continuously into both distinct parts or zones 10a and 10b of the preform, such that it is not possible to physically separate the two parts without damaging one or both of them. The presence of reinforcing fibers common to both zones gives the resulting preform sufficient mechanical strength so that subsequent manufacturing steps of the composite structures on each of these zones can be carried out without affecting the preform, and in particular without damaging it.

[0038] Due to the environmental constraints specific to each of the parts or zones described above, each will be subjected to a different treatment method from one zone to another in order to obtain a different composite material structure from one zone to another. Each distinct composite structure will thus be able to meet locally different functional requirements.

[0039] The following steps illustrate in a very schematic way, successively, the realization of a first metallic composite structure, on a first zone of the preform, here the lower zone 10a, using a first processing method (here introduction of a first matrix in order to form a metallic matrix composite structure) and the realization of a second composite structure, on the second adjacent zone of the preform, here the upper zone 10b, using a second processing method (here introduction of a second matrix in order to form an organic matrix composite structure; however, another matrix can alternatively be used).

[0040] Figure 1B illustrates more precisely than Figure 1A the preform 10 with the reinforcing fibers fl and f2 in the two zones 10a and 10b. The fibers fl and f2 shown here are straight. In this figure, the dimensions of zones 10a and 10b have been represented in a manner consistent with the zones or parts of the blade to which they are intended to correspond: a narrower part for the blade root (10a) and a wider part for the blade (10b).

[0041] Normally, when the preform is produced, for example in 3D weaving, the resulting preform is then cut to the desired dimensions, which correspond approximately to those of the part to be manufactured. Here, the preform 10, comprising the formed areas 10a and 10b, was obtained by cutting. However, fibers fl in the warp direction of the preform, which are intended to be drawn, were not cut and are intentionally left long so as to extend beyond the preform on either side. cut, here at the top and bottom, according to the vertical positioning of the preform. Note that the uncut fibers fl are those extending into both zones 10a and 10b. The fibers fl extending only into the second zone 10b have, on the other hand, been cut lengthwise. The length of the remaining long fibers fl is chosen to provide sufficient grip on these fibers to allow tension to be applied to them by some device. To this end, the length of the fibers fl extending longitudinally above the preform 10 is longer than that of the fibers extending below this preform, since, in this example, the tension will be applied to the fibers in the upper part. As shown in [Fig. 1B], the fibers fl protruding from the preform 10 constitute a set of reinforcing fibers extending in a direction of stress application which, in this case, is vertical.These fibers each have two opposite ends, namely an upper end fl.1 and a lower end fl.2. .

[0042] As shown in [Fig. 1C], the lower ends fl.2 of the fibers protruding below the preform are held in a fixed vertical position, for example, by means of a support 20 to which they are temporarily attached. This support 20 can, for example, be part of the mold in which the first zone of the preform will undergo a processing method to form a metallic composite structure.

[0043] Figure 1D illustrates a possible example of a device 30 for applying Tensile stresses are applied to the entire set of reinforcing fibers fl that protrude beyond the preform 10. The device 30 includes, for example, intermediate elements such as rollers 32, 34 that allow the upper ends fl.l of the fibers fl to be turned downwards, supported here by two successive, parallel rollers spaced apart. Alternatively, other elements or mechanisms for changing the orientation of the upper ends fl.l of the reinforcing fibers can also be used. The device 30 also includes, for example, a set of counterweights 36 attached to the turned (downward-facing) upper ends fl.l of the fibers fl in order to exert controlled tensile stresses on all of these fibers.The choice of tensile stress values ​​to be applied to the fibers depends on the final operating conditions of the relevant part of the composite component. For example, tilting blades such as those used in OGVs do not require as much preload as fan blades because they are not subjected to rotational movement. Generally, the tensile stress values ​​to be applied to the first zone 10a are chosen so that, in the final component, the portion corresponding to this first zone, in this case the blade root, is prestressed in compression at stress values ​​between 20 and 80 MPa. When using the... In this part, this internal compression will compensate for the tensile forces generated by centrifugal forces. Such local prestressing of the preform thus gives the final composite part (blade) improved fatigue resistance compared to the prior art.

[0044] As shown in [Fig. 1E], after applying tensile stresses to all the reinforcing fibers, the first zone 10a of the preform is placed in a mold 40 into which a metallic composite matrix is ​​introduced to trap the reinforcing fibers of this zone. Operating conditions, particularly temperature and pressure, specific to the production of a metallic composite structure are then applied.

[0045] Figures 1F and IG illustrate in more detail the realization of the metallic composite structure on the first zone 10a. In these figures, only the first zone 10a is represented, the upper zone 10b being deliberately omitted for the sake of simplification.

[0046] Thus, the first zone 10a is placed in the mold 40 ([Fig.1F]) and it will be noted that the lower ends fl.2 of the fibers fl visible on the [Fig.1B] can be fixed to the bottom of the mold instead of being fixed to the support 20 of figures IC and 1D for their retention in position before stretching.

[0047] Figure 1G illustrates a step of introducing a liquid metal M (introduction of a metal matrix) into the mold so that the metal is in contact with the first zone 10a of the preform and can impregnate all the reinforcing fibers constituting this first zone. The internal part of the mold with which the first zone 10a of the preform is in contact is shaped to give this zone the desired shape (here intended to form the root of the blade).

[0048] The metal can for example be poured by gravity inside the mold (for example from a container 42) or injected at low pressure (for example with a pressure on the order of a few MPa) into the latter by a known means.

[0049] In the described embodiment, the metal is, for example, aluminum, and the applied temperature is substantially equal to the melting point of the metal matrix, which is approximately 660°C for aluminum. Other metals are, of course, possible depending on the functional requirements that the first zone 10a of the part must meet. For example, titanium can be used to form the metal matrix, and the applied temperature is substantially equal to the melting point of the metal matrix, which is approximately 1660°C for titanium.

[0050] During this step, 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.

[0051] Next, a cooling step can be applied to the assembly formed by the Reinforcing fibers and the metal matrix are introduced into the first zone 10a of the preform to obtain a solidified metal-based composite structure for this zone. During cooling, the metal matrix, for example, goes from its casting temperature (above 660°C for aluminum, for example) to ambient temperature. Then, if necessary (due to manufacturing time or for improved material quality, for example), the cooling of the matrix can be optimized. A ventilation device (blowing cold / ambient air onto the part to remove heat) or a cooling channel system (a system of channels integrated into the mold that circulates a cold / ambient fluid to remove heat from the part inside the mold) can be implemented, for example.

[0052] The first area thus treated is represented by reference 10a' in the remainder of the exposition.

[0053] Once the metallic composite structure has solidified, the tensile stresses applied along the direction of stress application to all the reinforcing fibers can be released. The portions of reinforcing fibers extending beyond the preform 10, in which the first zone 10a comprises a metallic composite structure, are then cut to the desired length to continue the manufacturing process.

[0054] Optionally, as described for holding the second opposing ends fl.2 of the reinforcing fibers in a fixed position before applying tensile stresses ([Fig.1H]), the first zone 10a of the preform is placed in the mold 40. A first pour of metal can then be carried out in the mold 40 to seal the ends fl.2 to the mold before applying tension to the reinforcing fibers fl. It should be noted that the portion of the fibers including the ends fl.2 that is thus bonded to the mold will not be subjected to compressive stress like the rest of the fibers fl in the final part and, for this reason, will not form part of the final part.

[0055] This will allow, after solidification of this first portion or quantity of metal around the ends fl.2 of the fibers in the mold, the homogeneous solidification of all the fibers fl arranged in this first zone and then the application of a homogeneous tension to all these fibers, particularly from their ends fl.1. More specifically, prior to the application of tensile stresses on all the reinforcing fibers fl along the direction of stress application, a first portion or quantity of metallic composite matrix is ​​introduced into the first zone 10a located in the mold 40. Operating conditions, particularly temperature and pressure, are applied to this first zone 10a in order to create a first incomplete composite structure from the Reinforcing fibers of the first zone 10a and of the first part or quantity of metallic composite matrix introduced into this first zone. The first complete composite structure will only be produced after the application of tensile stresses, by introducing a second part or quantity of metallic composite matrix into the first zone 10a located in the mold 40 and by applying operating conditions, in particular of temperature and pressure, specific to the production of the first complete composite structure in order to achieve the same result as that obtained at the end of the steps of Figures 1F and 1IG which apply here.

[0056] According to a possible variant of the option described above, the first zone 10a of the preform is placed in the mold 40 and the opposite ends of the reinforcing fibers are fixed to this mold, for example, by means of a plurality of clamps fixed to the bottom of the mold (generally one clamp per fiber to be drawn). Then, a uniform tension is exerted on all of these fibers, particularly from their ends fl.l, and then a single metal pour is carried out in the mold under the conditions already described above in relation to the stage of [Fig.1G].

[0057] The second zone 10b of the preform is still untreated and currently comprises only the preform reinforcing fibers illustrated in Figures 1A-E. The longitudinal reinforcing fibers fl of the preform, which extend lengthwise across the two zones of the preform, thus have, on the one hand, a first portion of their length located in the first treated zone 10a', which is now part of the first metallic composite material structure produced as described above, and, on the other hand, a second portion of their length located in the second, as yet untreated, zone 10b. These second portions of longitudinal fibers are thus physically connected to the first zone via the first portions to which they remain attached.It should be noted that only a portion of the total reinforcing fibers fl of the preform can extend from one zone to another, while the remaining portion of the reinforcing fibers of the preform may extend only in one or the other of these zones, insofar as a significant fraction of the reinforcing fibers extends into both one zone and the other zone, thus ensuring physical continuity between these zones.

[0058] Steps (not shown) of demolding, then deburring or machining of the first metallic composite structure 10a' arranged, for example, on a support can, for example, be carried out.

[0059] Figure II schematically illustrates the positioning of the second, as yet untreated, zone 10b of the preform inside a second mold or container 50, leaving the first, already formed, metallic composite structure 10a' outside this mold. A peripheral sealing system 52 can be provided at the junction between the two zones 10a' and 10b in order to hermetically seal the mold 50 onto 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 realization of the composite structure.

[0060] The internal part of the mold 50 with which the second zone 10b of the preform is in contact is shaped so as to give the desired shape to this zone.

[0061] A pressure injection system 54 ([Fig. U]) for a second matrix M', here an epoxy resin, is implemented to inject a controlled quantity (volume) of resin into the mold 50 under pressure through an orifice 50a from a reservoir and, for example, a pumping device. As an example, the well-known resin transfer molding or RTM technique (known in English as "Resin Transfer Molding") can be used. The temperature of the epoxy resin is approximately 150°C and the pressure in the mold is approximately 10 bar.

[0062] It should be noted that the temperature used during this step is lower than that used for the fabrication of the first metallic composite structure. Indeed, fabricating the composite structures in the reverse order of that described would not be feasible because it would lead to degradation of the first composite structure obtained.

[0063] The introduction of the resin inside the mold 50 allows the entire untreated reinforcing fibers of the second zone 10b to be impregnated or coated with this matrix.

[0064] Once the resin has been completely injected into the mold, the assembly formed by the reinforcing fibers and the resin introduced into the second zone (organic matrix) is to be allowed to cool and harden in order to obtain an organic-based composite structure for this zone. The second zone thus treated is represented by reference numeral 10b' in [Fig. 1K].

[0065] Demolding steps, then deburring or machining of this second zone are then carried out in order to obtain the part in composite material illustrated very schematically on [Fig.lK] and which comprises the two adjacent composite structures of the blower blade 10' thus manufactured.

[0066] 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.

[0067] It should be noted that the preform may comprise several types of fibers, possibly with several lengths and diameters. For example, the preform may comprise carbon fibers and glass fibers.

[0068] According to an alternative embodiment not shown, the preform comprising fibers Reinforcement elements that will be subjected to preload may consist only of unidirectional fibers or warp threads. Tensile stresses will then be applied along the direction of stress application, corresponding to the direction of the unidirectional fibers or warp threads of the preform. A blade root can thus be formed from such a preform.

[0069] According to an alternative embodiment not shown, it is possible to implement the manufacturing process for a part made of composite material by applying tensile stresses to a set of reinforcing fibers extending in a different direction of stress application, such as, for example, in the direction in which the fibers f2 of [Fig. 1A] extend. Everything described above also applies to such an alternative embodiment, and it is, for example, possible to apply tensile stresses to fibers f2 in the first zone 10a. Clamps can be attached to one end of these fibers f2 to hold them in a fixed position, while tension is applied to the opposite ends of these fibers.

[0070] In general, the invention relates to a method for manufacturing a part made of composite material from a preform comprising reinforcing fibers extending in at least one direction and having several zones. The preform has at least two adjacent zones such that at least some of the reinforcing fibers of the preform have a length extending into said at least two adjacent zones, in said at least one direction, so as to ensure continuity of the reinforcing fibers from one zone to the other, the method comprising the following steps: -application of tensile stresses on a set of reinforcing fibers along said direction at least one direction, called the direction of stress application, -introduction of a metallic composite matrix into a first of said at least two adjacent zones which includes stretched reinforcing fibers and application to this first zone of operating conditions, in particular of temperature and pressure, specific to the realization of a first composite structure from the reinforcing fibers of the first zone and the metallic composite matrix introduced into this first zone, -after solidification of the first composite structure, release of the tensile stresses applied to the entire reinforcing fiber assembly along the direction of stress application, - introduction of a composite matrix into a second of said at least two adjacent zones and application to this second zone of operating conditions, in particular of temperature and pressure, specific to the realization of a second composite structure from the reinforcing fibers of the second zone and the composite matrix introduced into this second zone.

[0071] According to this general method, tensile stresses can be applied in one direction, namely the direction of extension of the reinforcing fibers which extend in said at least two adjacent zones, or in another direction, for example, a direction of extension of other reinforcing fibers which is perpendicular to the first direction.

[0072] Figure 2 illustrates an example of an embodiment of a turbomachine (turbojet) 70 (shown here enclosed, although it can be unenclosed) comprising a fan 72 which incorporates fan blades 74 manufactured according to the process described above. It should be noted that the blades manufactured by the process described above can be rotor blades of a turbomachine that is not necessarily a fan, or even stator blades such as OGV-type straightening blades (an acronym meaning "Outlet Guide Vane" in Anglo-Saxon terminology).

[0073] Fig. 3 illustrates an example of a blower blade 74 used in the blower 72 of Fig. 2 where the blade comprises a foot 74a and a blade 74b.

[0074] According to another embodiment, the process can be used to manufacture a part made of composite material comprising three distinct zones with heterogeneous functionalities.

[0075] By way of example, such a part may be a turboprop propeller.

[0076] The preform of such a propeller comprises three distinct zones: a first zone corresponding to the propeller root, a second zone corresponding to the propeller leading edge, which is subject 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, some of the reinforcing fibers from the first zone extend into the second zone adjacent to the first, and another portion of the reinforcing fibers from the first zone extends into the third zone adjacent to both the first and second. Thus, the first and second zones are spatially connected to each other by some of the reinforcing fibers, and the first and third zones are spatially connected to each other by another portion of the reinforcing fibers.

[0077] In this example, the preform's reinforcing fibers are made of silicon carbide (SiC). The first area of ​​the foot is treated to create a metal matrix composite structure, for example, using a titanium matrix, in particular Ti-6A1-4V. The second area of ​​the leading edge can be treated to create a metal matrix composite structure, for example, also using a titanium matrix, in particular Ti-6A1-4V. The third area can be treated to create an organic matrix composite (OMC) structure, for example, using an epoxy matrix.

[0078] 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 execution of Each composite structure is treated by processing the first zone using the method requiring the highest temperature, and the same procedure is followed for subsequent zones. Thus, the first zone of the titanium base (temperature of 1660°C), prestressed as described above, is produced, then the second zone of the titanium leading edge is treated (temperature of 1660°C), and finally the third zone for the remainder of the blade in CMO (temperature of 150 / 200°C). Metallic parts or zones are preferably treated by gravity casting, using a casting operation with the area of ​​interest located at the bottom. The procedure described above with reference to Figures 1A-K can also be applied here, possibly with some adjustments within the capabilities of a person skilled in the art.

[0079] The process can be used to manufacture a composite part with a greater number of heterogeneous areas to be treated than envisaged above.

[0080] Although the present description refers to specific 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

Demands

1. A method for manufacturing a part made of composite material (10') from a preform (10) comprising reinforcing fibers (fl, f2) extending along at least one direction and having several zones, characterized in that the preform has at least two adjacent zones (10a, 10b) such that at least some reinforcing fibers (fl) of the preform have a length extending into said at least two adjacent zones, along said at least one direction, so as to ensure continuity of the reinforcing fibers from one zone to another, the method comprising the following steps: - application of tensile stresses on a set of reinforcing fibers (fl) along said at least one direction, called the stress direction,- introduction of a metallic composite matrix (M) into a first (10a) of said at least two adjacent zones comprising stretched reinforcing fibers and application to this first zone of operating conditions, in particular of temperature and pressure, specific to the realization of a first composite structure from the reinforcing fibers of the first zone and the metallic composite matrix introduced into this first zone, - after solidification of the first composite structure, release of the tensile stresses applied to the set of reinforcing fibers along the direction of stress application, - introduction of a composite matrix (M') into a second of said at least two adjacent zones and application to this second zone of operating conditions, in particular of temperature and pressure,specific to the creation of a second composite structure from the reinforcing fibers of the second zone and the composite matrix introduced into this second zone.

2. A manufacturing method according to claim 1, characterized in that the application of tensile stresses on the assembly of reinforcing fibers along the direction of stress application is carried out at the first ends (fl.1) of the reinforcing fibers (fl) of the assembly of reinforcing fibers, while the second opposite ends (fl.2) of the reinforcing fibers of the assembly of reinforcing fibers are held in a fixed position.

3. A manufacturing method according to claim 2, characterized in that, prior to the application of tensile stresses on the entire reinforcement fiber assembly along the direction of stress application, a first part of the metallic composite matrix is ​​first introduced into the first zone (10a) which includes the second opposite ends (fl.2) Reinforcing fibers (fl) of the set of reinforcing fibers and operating conditions, in particular of temperature and pressure, are applied to this first zone in order to produce a first incomplete composite structure from the reinforcing fibers of the first zone and the first part of metallic composite matrix introduced into this first zone, the first complete composite structure being produced, after the application of tensile stresses, by introducing a second part of metallic composite matrix into the first zone and applying operating conditions, in particular of temperature and pressure, specific to the production of the first complete composite structure.

4. A manufacturing method according to any one of the preceding claims, characterized in that the applied tensile stresses are dimensioned so that, in the composite material part thus manufactured, the part of the part corresponding to the first zone (10a) is prestressed in compression at stress values ​​between 20 and 80MPa.

5. A manufacturing method according to any one of the preceding claims, characterized in that the preform (10) comprises two distinct adjacent zones (10a, 10b), the matrix introduced into the second zone (10b) of the preform being chosen from an organic matrix, a metallic matrix, a ceramic matrix.

6. A manufacturing method according to any one of claims 1 to 4, characterized in that the preform comprises three distinct zones adjacent in pairs, the matrix introduced into each zone being chosen from an organic matrix, a metallic matrix, a ceramic matrix.

7. A manufacturing method according to claim 6, characterized in that each of the three distinct zones is adjacent to the other two zones.

8. A manufacturing method according to any one of the preceding claims, characterized in that the reinforcing fibers comprise carbon fibers, silicon carbide fibers, glass fibers, boron fibers, alumina fibers.

9. A manufacturing method according to any one of the preceding claims, characterized in that the preform is formed in one piece.

10. A composite material part, characterized in that it comprises several distinct composite structures, including a first metallic composite structure, produced by the process according to any one of the preceding claims, the tensile stresses applied being dimensioned so that, in the composite material part thus manufactured, the part of the part corresponding to the first zone (10a) is prestressed in compression at stress values ​​between 20 and 80 MPa.

11. A composite material part according to claim 10, characterized in that the separate composite structures are intended to be subjected each to a distinct mechanical stress and / or temperature field from one area to another.

12. Part made of composite material according to claim 10 or 11, characterized in that the part is a turbomachine rotor blade or a turboprop propeller.

13. A composite material part according to claim 12, characterized in that, when the part is a turbomachine rotor blade, the rotor blade (74) comprises, on the one hand, a blade foot (74a) forming a composite structure made from a metallic matrix (CMM) and corresponding to the first zone (10a) of the preform and, on the other hand, a blade (74b) forming a composite structure made from an organic matrix (CMO).

14. Turbomachine rotor, characterized in that it comprises a plurality of parts made of composite material according to any one of claims 10 to 13.

15. Turbomachine comprising a turbomachine rotor according to claim 14.

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