WO2003035380A1

WO2003035380A1 - Method for making extruded profiles having a specific surface state made of fiber-reinforced synthetic resins and machine therefor

Info

Publication number: WO2003035380A1
Application number: PCT/FR2002/003662
Authority: WO
Inventors: Alexandre Hamlyn; Yvan Hardy
Original assignee: Coriolis Composites
Priority date: 2001-10-26
Filing date: 2002-10-24
Publication date: 2003-05-01
Also published as: FR2831479B1; FR2831479A1

Abstract

The invention concerns a method for making aerodynamic structures using an assembly of mandrels and consisting in: a) a first deposition of fibers on each mandrel to coat each mandrel; b) vacuum compaction of said fiber deposition and/or infusion of said deposition with a polymerizable resin; c) polymerizing the first deposition; d) setting and locking the mandrels in a hollow mould so as to defined free spaces in the mould; e) injecting resin in the mould so as to fill at least partly the free spaces, to produce reinforcements in an envelope of the structure or in internal partitions of said structure; f) polymerizing the resin and the assembly formed, and stripping said assembly; g) carrying out a second fiber deposition; h) setting the assembly in a hollow mould and performing step b); i) polymerizing the assembly and stripping the resulting final structure; j) carrying out a finishing treatment of the structure obtained at step i).

Description

Method for manufacturing profiles with a specific surface finish in synthetic resins reinforced with fibers and machine for carrying out the method

The invention relates to a method of manufacturing aerodynamic structures with a specific external surface condition in synthetic resins reinforced with fibers carried out on a machine for depositing in winding or in contact with fibers on such structures.

The rest of the text will mention terms or expressions the definition of which is given below:

Thus, by "tackifying agent" is meant an agent or product making it possible to fix fibers at least temporarily between them and / or on a support. Such a tackifying agent can be an adhesive or a resin.

By "folds" is meant a layer or laminate of fibers, for example glass fibers.

By "sampling" is meant the number of layers of fibers, the thickness of each layer and the orientation of the layers.

By "foaming resin" is meant, for example, a resin which, under certain conditions, turns into foam to spread in free spaces or cavities of a mold. An example of foaming resin is expandable epoxy resin.

By "continuous fiber" is meant a fiber which is not cut or cut during its deposition on a mandrel or a support.

By "staple fibers" is meant fibers cut at specific locations, to adapt to the shape and / or thickness constraints of the deposited layers.

Aerodynamic structures with a specific external surface condition in fiber-reinforced synthetic resins are traditionally manufactured, by contact molding of fabrics or wicks, in hollow molds in two half-shells, or on male molds in a single envelope . The fibers are either already impregnated with resin and polymerized after deposition with compaction, or deposited dry, with optionally a tackifying agent, and impregnated either manually by contact, or by infusion, transfer or injection of resin, with tools of the counter type. - hollow mold or flexible tarpaulin. The molding techniques in hollow molds in two half-shells generally require manual removal of the fabrics, for the production of the various elements of the external envelope and for the internal reinforcements, such as the partitions and the sandwich structures. Traditionally, these elements are then deburred, glued and laminated again together, putty and polished entirely manually. The main drawbacks of this technique lie on the one hand in the need for a large and skilled workforce, on the other hand in the fragility of the final product due to the bonding of the different elements constituting the final profile. In addition, the scraps of raw materials are significant due to the many cuts.

The molding techniques in a single envelope on male molds are either manual or automated, in particular according to the technique of automated depositing of fibers by winding or in contact. In the case of manual implementation, the parts produced are generally of reduced size and the fibers deposited are not continuous, due to the difficulty of handling and positioning the materials and large tools in a precise manner. Thus the parts produced do not have an optimal structure due to the discontinuity of the fibers and the size of the final product is limited.

Automated fiber deposition techniques by winding or in contact have been proposed several times to manufacture the internal structure and / or the external envelope of aerodynamic structures. These techniques automate the fiber and resin deposition phase, but do not allow sandwich type structures to be produced without the manual deposition phase. In addition, the core of these sandwich structures is in the form of plates of constant thickness which do not allow an optimal structure to be obtained with variable and specific thicknesses at each point of the envelope or partitions. Another drawback of these automated techniques lies in their application for the manufacture of very long structures. Indeed, due to the difficulty of handling or setting in motion the mandrels without significant deformations, the configuration of current devices for automated depositing of fibers by winding or in contact does not allow precise fibers to be deposited on a mold. internal or mandrel in movement which can bend a few centimeters for lengths of more than 25 m.

Document EP 0 657 646 discloses, for example, a device and a method for manufacturing aerodynamic structures, using longitudinal and crossed windings of fibers associated with a synthetic resin. Hollow cores or rigid foam cores are introduced into the core of the windings. A priori such a process does not a priori make it possible to obtain satisfactory mechanical properties for producing aerodynamic structures of very large dimensions, in particular of 25 m and more. In addition, such a method does not make it possible to obtain laminates of large and decreasing thickness over the length of the structures.

The documents FR 2 773 513, EP 0 225 563 and EP 0 680 818 describe machines and systems for the automated deposition of fibers by winding or in contact for the production of various large composite structures, in particular aerodynamic profiles. These documents do not describe a solution for depositing continuous fibers on large mandrels or molds in movement and bending by a few centimeters.

Documents WO 99/22932 and US 4 699 683 describe depositing machines and systems for producing various large composite structures, in particular aerodynamic structures, but the fibers are not continuous because the envelope is made in two half -shells which are then assembled by gluing, which weakens the final product. A disadvantage of existing machines and devices for automated fiber deposition by winding or in contact is the low capacity for depositing materials per unit of time, compared to the total amount of material to be deposited for the production of large aerodynamic profiles. For example, the manufacture of a 40 m long wind turbine blade with a mass of 10 tonnes would require a winding and laying time of 100 hours with a machine depositing 00 kg per hour.

Another disadvantage of current machines and devices for automatic fiber deposition is their high price because they are generally composed of specific elements, such as carriages, axes and mechanical connections, made to measure and therefore at high price, given the low series produced. Thus, the significant manufacturing times would not be profitable because of the hourly cost of such a machine that it would not be possible to amortize with such a low production rate.

In addition, these special machine-type designs guarantee lower levels of reliability than machines produced from reliable standard elements in many applications. Finally, their specific function for depositing fibers does not allow other automated tasks to be carried out, such as surface treatment or machining.

The object of the invention is to provide a method of manufacturing aerodynamic structures which do not have the drawbacks of the state of the art and which make it possible to improve the mechanical characteristics of said structures.

Another object of the invention is to provide a method of manufacturing aerodynamic structures making it possible to obtain a specific surface condition and to increase the maximum dimensions of said structures, while reducing the manufacturing costs.

The aims assigned to the present invention are achieved by means of a process for manufacturing aerodynamic structures extending in a longitudinal direction and a transverse plane, using an assembly of at least two mandrels and consisting in: a) Carrying out a first deposit of fibers on each mandrel to coat each mandrel, b) Vacuum compacting the deposit of fibers and / or infusing said deposit with a polymerizable resin, c) Polymerizing the first deposit, d) Positioning and wedging the mandrels coated in a hollow mold so as to delimit free spaces in the mold, e) Inject resin into the mold so as to fill at least partially the free spaces, so as to make reinforcements in an envelope of the structure or in internal partitions of said structure, f) polymerizing the resin and the assembly thus formed, and demolding said assembly, g) carrying out a complementary deposit of fibers on the assembly e, obtained in step (f). h) Place the assembly in a hollow mold and either proceed again to step (b), or inject resin into the hollow mold, i) Polymerize the assembly and unmold the final structure obtained, j) And carry out a finishing treatment of the structure obtained in step (i). According to one embodiment, the method according to the invention consists, during step (e), of integrating into the free spaces, solid inserts in addition to the injection of resin. According to another embodiment, the method according to the invention consists in step (e), using foaming resin whose expansion in the structure and within a template disposed in the mold , makes it possible to constitute reinforcements in said aerodynamic structure.

Other characteristics and advantages will also emerge from the detailed description below, with reference to the appended drawings, given by way of examples in which:

- Figure 1 is a schematic perspective view of an aerodynamic structure according to the invention;

- Figure 2 is a schematic exploded perspective view of the various internal and attached components of the structure of Figure 1;

- Figure 3 is a schematic cross-sectional view along line in-iii of Figure 1 of an aerodynamic structure according to the invention;

- Figure 3a is an enlarged detail of Figure 3; - Figure 4 is a schematic cross-sectional view along line IV-IV of Figure 1, of an aerodynamic structure according to the invention

- Figure 4a is an enlarged detail of Figure 4;

- Figure 5 is a schematic perspective view of the first step of winding and / or contacting fibers on a mandrel;

- Figure 6 is a schematic perspective view of a vertical machine for the manufacture of large blades during a second step of depositing fibers on the aerodynamic structure; - Figure 7 is a schematic perspective view of a vertical machine for the manufacture of large blades during disassembly of the profile after the second step of removing fibers;

- Figure 8 is a schematic cross-sectional view of the hollow mold in which is deposited a template for imposing dimensions and an internal surface state during an injection and expansion step of the foam core;

- Figure 9 is a schematic exploded perspective view of the mandrels and the attached elements positioned in the hollow mold with a template;

- Figure 10 is a schematic cross-sectional view along the line x-x of Figure 9; mandrels and inserts in the hollow mold with a template after the expansion and polymerization phase of the resin; - Figure 11 is a schematic perspective view of the withdrawal of three mandrels from the structure obtained after injection and polymerization of the resin;

- Figure 12 is a schematic perspective view of the elements added and glued to the structure; - Figure 13 is a schematic perspective view of a second step of depositing in winding and / or in contact with fibers on the structure;

- Figure 14 is a schematic cross-sectional view along line x-x of Figure 9 of the structure in the hollow mold with the resin injected;

- Figure 14a is an enlarged detail of Figure 14;

- Figure 15 is a schematic perspective view of the operation of removing the mandrel from the finished structure.

By way of example, an embodiment of the object of the invention has been described below and illustrated diagrammatically in FIGS. 1 to 15, figures in which three orthogonal directions L, T and E are shown. longitudinal, called L, corresponds to the axis of rotation of a fiber depositing machine and to the axial direction of the blade root (part to be fixed on the external element such as the rotor hub) at its free end. A transverse direction, named T, is orthogonal to the direction L and located in a horizontal plane passing through L. A direction called in elevation, E is orthogonal to directions L and T.

The following description makes it possible to understand how an aerodynamic structure according to the invention is manufactured, such as a wind turbine blade 1 shown in the schematic perspective view of FIG. 1, and what are the new performances brought about.

Before any manufacturing, a study, carried out at design, allowed to know the shape of the profile to be manufactured and the different constraints which will be submitted to it. Part of this study defines the thickness and number of laminates, the orientation of the fibers in the different parts of the profile as well as the direction, dimensions and locations of partitions and possible sandwich structures.

FIG. 2 shows a schematic exploded perspective view of the various internal components 2, 3, 4, 5, 6, 7, for example provided for producing the blade 1. The internal components thus comprise mandrels 2, 3, 4, 5 solid or hollow, an insert 6 and a free end

7.

The blade 1 comprises a foot 8 intended to be mounted on a wind turbine rotor and an elongated part 9 in a sandwich structure. Figure 3 is a schematic sectional view of the structure along the line iii-in of Figure 1, with a structure composed of an envelope 10 whose function is to create the desired aerodynamic force and internal partitions 11 which provide the strength and stiffness required.

Laminates 12 and 13 composed of pleats oriented approximately in the direction L and of a decreasing thickness of the foot

8 of the blade 1 at its free end, work in traction and compression and take up the bending stresses mainly due to the aerodynamic pressure and less due to the own weight of the blade.

It can be seen in FIG. 3 that the laminates 12 and 13 are grouped together in zones distant from the neutral planes close to the planes represented by L, T and E, L, in order to increase the moments of inertia of the blade relative to the main stresses.

Laminates 14 and 15 shown for example in FIG. 3a and coating the mandrels 2, 3, 4 and 5 are composed for example of 80% of plies oriented at +/- 45 °, to 10% of plies at 90 ° and to 10% folds at 0 ° relative to the direction L. The laminates 14 and 15 mainly take up the constraints of shear between the laminates 12 and 13, the local stresses due to the external pressure on the casing 10 and the torsional stresses.

The blade 1 also locally contains foam 16, obtained for example from a foaming resin, of variable thickness, providing inertia to the envelope 10 and to the partitions 11 in order to limit the thickness of the laminates 14 and 15. It is intended that, in this case with three partitions 11, the number of plies at +/- 45 ^° and 90 ° of the laminate 14 must be identical at the level of the partitions 11 and at the level of the envelope 10 It is also expected that the number of plies at +/- 45 ⁰ and 90 ° of the laminate 14 at the partitions 11 must be identical to the number of plies at +/- 45 ⁰ and 90 ° of the laminate 15 at the level of l 'envelope 10. It is thus possible to have, at the partitions 11 and the laminates 14, symmetries as regards the numbers of folds.

It is also intended that the number of plies at 0 ° of the laminates 14 and 15 is identical to the level of the envelope 10. It is also provided that the arrangement and the number of the plies of the laminates 14 and 15 are defined so as to obtain a symmetrical structure on either side of the foam 16 at the level of the partitions 11 and of the envelope 10.

Figure 4 is a schematic sectional view of the leg portion 8 of the blade 1 along the line IV-IV of Figure 1 with a structure composed of the casing 10 whose function is to transmit the binding stresses to a external element, such as the rotor of a wind turbine, from part 9 to foot 8 shown in FIG. 2. The laminates 13 in greater quantity on foot 8 than on part 9, are regularly arranged around a profile cylindrical to distribute the main stresses at the attachment points of the blade 1, covering the plies of the laminates 14 deposited over the entire length of the blade 1. The laminates are covered by the plies of the laminates 15 over the entire length of the blade 1. The strong torsional, bending and shearing and buckling stresses are also taken up by an additional laminate 17 on the foot 8 (composed of plies approximately balanced at +/- 45 ⁰ , 90 ° and 0 ° relative to L) of a thick decreasing ssor from foot 8 to part 9.

The total thickness of these laminates 13, 14, 15, 17 is sufficient to ensure the stiffness of the envelope 10 on the foot 8 and does not require a foam core 16 like that provided on the part 9, the thickness becomes progressively zero from part 9 to part 8. It is established that the orientation, continuity and arrangement of the plies of the various laminates thus obtained best meet the constraints of shape, strength and stiffness of a wind turbine blade 1, while being achievable according to the method and with the machine described below. The thickness of each fold as well as the number of internal partitions 11 (which may be zero) can easily be calculated and adapted according to the size of the aerodynamic structure, the materials used and the expected load assumptions.

FIG. 5 is a schematic perspective view which illustrates the first step of depositing by winding and / or in contact with fibers on the mandrel 3, with a machine 19 on which all the steps of the process described below can be carried out. This machine 19 is made up of standard elements, such as robots 20 on which different systems can be mounted such as a head 21 for depositing by winding and / or in contact with fibers, a machining or projection head. These robots 20 of a variable number are mounted on linear axes 22 and the mandrel 3 is rotated by means of a positioner 23 and a tailstock 24. Depending on the size of the structure to be produced, and also of the quantity of material to be deposited or machined, the machine 19 can have a horizontal configuration as shown in FIG. 5, or a vertical configuration, as shown schematically in FIG. 6. This figure shows a plate 24 with a lifting system and guide 25, using standard solutions of traditional freight elevators such as cables or jacks with a counterweight, which allows to embark more than two robots 20 to deposit by winding and / or simultaneously contacting more material. This vertical configuration makes it possible to eliminate the problem of the deflection of the mandrel 3 and to reduce the risk of detachment of material or folds during the rotation of the mandrel. In both configurations, an encoder measuring the speed and position of the positioner 23 with a vertical or horizontal axis, controls the plate 24 or the carriages 20a, having their own coding system and supporting the robots 20 independent of each other. The assembly and disassembly of the mandrels and structures is carried out in the case of the vertical machine 19 using the positioner 23 which switches the profile at the foot, as shown in Figure 7. The axis of rotation is provided for that the structure is in a favorable position, that is to say to limit its deflection during tilting, for example around the axis E. In the case of a horizontal machine 19, the mounting and dismounting of the blade 1 is carried out in the traditional way. The internal and external dimensions of the blade 1 being known, internal molds, for example four mandrels 2, 3, 4, 5 whose external dimensions correspond to the internal dimensions of the four components 2a, 3a, 4a and 5a of the blade 1, and a hollow mold 26, the internal face of which corresponds to the external dimensions of the blade 1 to be produced, were produced according to traditional techniques. They may consist entirely or in part of inflatable or flexible elements, in the case where the shape does not allow them to be removed after polymerization due to non-demouldable shapes, or in the case of bodies that are too weak over long lengths. In addition, they can in a certain embodiment, allow the compaction of the various folds which will cover them.

A first mandrel 3 corresponding for example to the internal shape of the element 3a is mounted on the machine 19 to optionally undergo a refining treatment on its external surface, such as the projection of a release agent and a tackifying agent by a spraying system mounted at the end of the robots 20, and possibly the installation of pins (not shown) at the ends of the mandrel 3.

Once this preparation is complete, the automatic depositing of fibers by winding and / or in contact is carried out so as to obtain the sampling defined during the design, using the heads 21 for depositing by winding or in contact with fibers, such as those that are found in the industry which make it possible to place and stick fibers, for example made up of prepreg wicks, continuous or discontinuous, which are mounted at the ends of the robots 20. This removal by winding and / or in contact begins for example by the plies of laminates 14 at 45 ° and - 45 °, at 88 ° and - 88 °, and 0 ° relative to the direction L and continuous between the two ends of the mandrel 3, as shown in FIG. 5 The plies at 0 ° of the laminates 12 or 13, depending on the mandrel which is covered, are then deposited longitudinally in the direction L, progressively reducing the number of layers in the area of the foot 8 of blade 1 at its end. é free, that is to say by interrupting the deposit at intermediate zones between the two ends. The other three mandrels 4, 5, 6 then undergo the same treatments and are all four polymerized according to known techniques, for example under vacuum at a temperature of 80 ° C. In parallel, a hollow mold 26 provided for the production phase of the foam core is prepared. For example, as shown in Figure 8, this mold 26 can be produced in two parts, the internal dimensions of which correspond to the final external dimensions of the blade 1, in which a template 27 is deposited in two parts, for example in composite with adequate thicknesses to adapt its dimensions and its state of internal surface at the stage of expansion of the foam core 16. The volume of this template 27 in two parts corresponds to the fibers and to the resin which will be deposited in a second phase, with their specific thickness at each point. In order to guarantee good adhesion of the bonding which will be carried out with the laminates 15 and 17, the internal surface state of this template 27 has an adequate roughness, which may require the removal of a release agent before injection or removal. resin.

During the positioning of the four mandrels 2, 3, 4, and 5 covered with their laminates 12, 13, and 14 in the mold 26 and the template 27, elements, such as the end 7 forming part of the blade 1, can be reported as shown in Figure 9. The end 7 can be made for example in the traditional way of fibers with an injection of resin. This end 7 has on the outside a smooth surface with the final external dimensions of the blade 1 and on the inside a rough surface to ensure quality bonding on the laminates 12, 13, and 14 covering the mandrels 2, 3, 4 and 5. Other reinforcements and / or fibers and / or inserts such as lightning conductor cables can be placed in the mold 26 and the template 27 so as to be impregnated or bonded with the foaming resin. A handling and wedging system 31 makes it possible to position all the mandrels in the mold 26 and the template 27 in order to keep them at a given distance from the internal wall of said mold 26 and between the mandrels 2, 3, 4, 5 This distance is specific to each part of the envelope 10 and of the three partitions 11 of the blade 1, and corresponds to the variable thickness of the foam reinforcements 16 provided for in the design.

Figure 10 shows schematically and in cross section along line xx of Figure 9, the mandrels 2,3, 4 and 5 covered with their laminates 12, 13, and 14 in the mold 26 with its template 27 after the phase of expansion of the foaming resin 16 which has been previously sprayed and / or injected, possibly in sequential steps. This foaming resin may for example be epoxy resin with a foaming agent which makes it possible to reduce the density of the polymerized foam. The foam 16 thus obtained on the one hand ensures bonding between the four mandrels 2, 3, 4, 5, and on the other hand a structural reinforcement.

Figure 11 is a schematic perspective view of the removal operation (see removal directions R) of the three mandrels 2, 4 and 5 of the structure 32 obtained after the polymerization of the foaming resin, with the mold 26 preferably held closed to block said structure 32 during withdrawal. The mandrel 3 is left in place to manipulate the structure obtained 32 and to keep the same position references during the next steps of the process. When designing the blade 1 and the mandrel 3, it was calculated that the centers of gravity of the assembly constituted by the mandrel 3 and the structure 32 obtained, which is subsequently covered with the laminates 15 and 17, are the as close as possible to the axis of rotation of the positioner 23 of the machine 19, in order to limit unbalances during the next folds removal steps. The structure 32 with its mandrel 3 is then removed from the template 27. Inserts can be added and glued, such as the element 6 shown in FIG. 12. The structure 32 is then manipulated on one side thanks to the end of the mandrel 3, on the other side thanks to a shaper 33 which holds the assembly by the finished end 7 and which positions it in the axis of the positioner 23 of the machine 19 during the next steps of the process, as can be seen in FIG. 13. A new step for depositing folds can also be carried out.

Before this removal, the structure 32 may possibly undergo on the machine 19 a refining treatment of its external surface, such as the projection of a tackifying agent by a spraying system mounted at the end of the robots 20 and / or deburring of the jointing surfaces of the foaming resin by means of a machining system mounted at the end of the robots 20. Once this preparation is complete, the automatic depositing of fibers is carried out so as to obtain the sampling defined during the design, using depositing heads 21 by winding and / or in contact with fibers mounted at the ends of the robots 20, as shown in FIG. 13. This step begins for example by depositing the plies of the laminates 15 and 17. The number of layers is gradually reduced from the foot 8 of the blade 1 at its other end, by cutting the fibers in intermediate zones between the two ends. The plies of the fibers of the laminates 15 and 17, for example pre-impregnated with a tackifying agent for their retention on the structure 32, can then be impregnated with an injection of resin. In this case, provision is made during the removal of fibers to leave adequate spaces between each group or wick of fibers in certain parts and / or layers, in order to facilitate the transfer of resin during injection. These spaces may be obtained by means of an adjustment on the depositing heads 21 by winding and / or in contact with the spacing of the pulleys or of the combs for guiding the wicks of fibers, or by means of narrower wicks not being not contiguous at the outlet of the heads 21. Also, drainage materials such as felts in the form of strips can be applied between the layers. In parallel, the hollow mold 26, the internal dimensions of which correspond to the final external dimensions of the blade 1, was prepared with the removal of the template 27 and possibly the deposition of a release agent and a thermoplastic or thermosetting film intended for protect and color the external surface of the blade 1. The structure 32 covered with the laminates 15 and 17 is then deposited in the mold 26, in order to carry out a transfer of resin, for example by means of assisted injection of the vacuum. Inserts, such as a trailing edge 34 can be added. FIGS. 14 and 14a are schematic cross-sectional views along line xx of FIG. 9 of the final structure 35 obtained once the resin has been injected and polymerized, which corresponds to the shape of the blade 1 finished, with the mold 26 and the mandrel 3 remained in place.

This final structure 35 is then removed from the mold 26 to be mounted on the machine 19, with the shaper 33 and the mandrel 3 which make it possible to keep the position references. The final structure 35 can then undergo a finishing treatment such as deburring of joint planes, cutouts for the assembly of inserts for fixing the profile to an external element and painting, thanks to the mounting on the robots 20 of the '' adequate equipment, such as a spray gun or milling and drilling spindle.

. The final structure 35 is then removed from the machine 19 and the mandrel 3 is removed according to the arrow R, as shown in FIG. 15. This final structure 35 corresponds to the blade 1, ready to receive inserts such as fixing flanges to then be mounted on a wind turbine rotor.

According to an exemplary implementation, the method according to the invention comprises the steps providing for: - positioning with the machine on a mandrel 2, 3, 4, 5 longitudinal corresponding to the internal shape of the structure or on several mandrels corresponding to the longitudinal internal cavities of the structure in the case where it has longitudinal internal partitions 11, pins and / or non-slip products, allowing an increase in the adhesion between the mandrel (s) 5 and the fibers which will come cover it; - deposit on the mandrel (s) by winding and / or in contact with the machine dry fibers or impregnated with resin or tackifying agent in directions and thicknesses defined during the design of the aerodynamic structure 32,

- pressurize the materials deposited on the mandrel (s) 2, 3, 4, 5 with vacuum compaction using a tarpaulin and / or carry out an infusion of resin under tarpaulin and polymerize the resin,

- Put in place this or these mandrels 2, 3, 4, 5 covered with the materials in the hollow mold 26 and wedge them in order to maintain them at a given distance from the internal wall of the hollow mold 26 and between them if they are several injecting foaming or non-foaming resin into the entire free space which corresponds to the thickness of the foam reinforcements 16 provided in each part of the envelope 10 and of any internal partitions 11 of the final structure,

- after polymerization of the foam, leave a full or hollow mandrel 3 so as to maintain the center of gravity of the part obtained, and subsequently covered with another layer of fibers, closest to the axis of rotation of the positioner of the machine, remove any other mandrels 2, 4, 5 and remove from the hollow mold 26 the assembly thus obtained,

mounting this assembly on the machine and depositing on this assembly by winding and / or in contact with the machine dry fibers or impregnated with resin or tackifier in directions and thicknesses defined during the design of the aerodynamic structure 32,

- pressurizing the materials placed in the external hollow mold 26 whose internal face corresponds to the external shape of the profile in order to obtain an external surface state identical to that of the internal surface of the hollow mold 26 and a determined resin content , by resin injection and / or resin expansion such as foaming resin, and / or by an increase in the volume of the mandrel (s), or pressurizing the materials by vacuum compaction using a tarpaulin and / or an infusion of resin using a tarpaulin, - After polymerization, unmold the profile obtained from the hollow mold 26 or from the tarpaulin and mount it on the machine to undergo a refining and / or finishing treatment such as deburring, painting and cutting, for example for the passage or the assembly of inserts to fix the structure to an external element, and / or for the evacuation of the mandrel 3.

The manufacturing process and the aerodynamic structures obtained by such a process have significant advantages:

Production is fully automated, thanks to the use of design software, finite element calculations, fiber deposition simulation and numerical control programming. The fiber depositing machine is an automated center for machining, spraying, winding and cutting. Thus, the risk of non-compliance is limited, on the one hand thanks to the automation which guarantees the reproducibility of the manufactured product, on the other hand thanks to the carrying out of the various operations via the same robots and assembly bench, improving the geometric precision ée the final structure.

The soul of the sandwich structure produced thanks to an expansion of foaming resin allows, compared to the traditional bonding of plates, to reduce production times, to guarantee a perfect bonding with the external and internal skins, and to have a thickness optimal and scalable at each point of the structure optimizing the amount of material and the weight.

The finished product has high mechanical qualities on the one hand thanks to the automatic deposition which makes it possible to deposit the fibers in optimal orientations, on the other hand thanks to the continuous fibers to the maximum, without in particular having a cut between the upper and lower face of the blade.

The positioning of the inserts is much more precise thanks to automated machining.

Common structures, such as laminates of significant thickness decreasing over the length of the structures as well as foam cores of variable thickness over a certain length of the profile, are possible thanks to the different stages of fiber deposition and the different techniques of resin impregnation and injection.

The maximum dimensions of the achievable structures are increased thanks to the vertical design of the fiber depositing machine, allowing the realization of the largest wind turbine blades. The realization of the machine implementing the method according to the invention from standard elements provides high reliability and a reduced cost of the assembly compared to existing machines.

The production rates are increased thanks to the plurality of fiber depositing heads which multiply the quantity of material deposited per hour, and the material losses are almost zero.

In addition, the external surface finish can be smooth or rough as required.

Finally, the process which is the subject of the invention is particularly suitable for the mass production of wind turbine blades and of various aerodynamic structures such as wings and masts.

Claims

1. Method for manufacturing aerodynamic structures (32, 35) extending in a longitudinal direction (L) and a transverse direction (T) and an elevation direction (E), using an assembly of mandrels (2, 3, 4 , 5) and consisting in: a) Performing a first deposit of fibers on each mandrel (2, 3, 4, 5) to coat each mandrel (2, 3, 4, 5), b) Vacuum compacting the deposit of fibers and / or infuse said deposit with a polymerizable resin, c) polymerize the first deposit, d) place and wedge the mandrels (2, 3, 4, 5) coated, in a hollow mold (26) so as to delimit free spaces in the mold, e) Inject resin into the mold so as to fill at least partially the free spaces, so as to make reinforcements in an envelope (10) of the structure (32) or in partitions internal (11) of said structure (32), f) polymerizing the resin and the assembly thus formed, and demolding said assembly, g) Effect use an additional deposit of fibers on the assembly obtained in step (f), h) Place the assembly in a hollow mold (26) and proceed either again to step (b), or inject resin in the hollow mold (26), i) polymerize the assembly and unmold the final structure (35) obtained, j) and carry out a finishing treatment of the structure (35) obtained in step (i).

2. Method according to claim 1, characterized in that it consists, during steps (a) and (g), in making the fiber deposits in contact and / or by winding.

3. Method according to claim 1 or 2, characterized in that it consists, during steps (a) and (g), of depositing dry fibers or fibers impregnated with a resin or a tackifying agent.

4. Method according to any one of claims 1 to 3, characterized in that it consists in using mandrels (2, 3, 4, 5) full or hollow, at least one of which is removed from the assembly consecutively to step (f) and whose last mandrel (3), or part of mandrel, serving as support during steps (g), (h), (i) and (j) is removed from the aerodynamic structure (35) after step (j).

5. Method according to any one of claims 1 to 4, characterized in that it consists in using a single mold (26) to perform the molding steps under (d) and (h) and in having a template (27 ) in said mold for step (d) so as to define the shape of the assembly after injection of resin during step (e).

6. Method according to any one of claims 1 to 5, characterized in that it consists during step (e) of integrating, in the free spaces, solid inserts in addition to the resin injection.

7. Method according to claim 5 or 6, characterized in that it consists, during step (e), of using foaming resin, the expansion of which in the structure (32) and within the template ( 27) makes it possible to constitute reinforcements in the aerodynamic structure (32).

8. Method according to any one of claims 1 to 7, characterized in that it consists in producing during the first deposition of fibers plies oriented substantially in the longitudinal direction (L) of the aerodynamic structure (32), in addition folds intended to coat the mandrels.

9. Method according to claim 7, characterized in that it consists in injecting the foaming resin between the laminates (12, 13, 14, 15) of plies having an identical sampling so as to obtain a symmetry of the envelope (10 ) and the internal partitions (11) relative to the number of folds.

10. Method according to any one of claims 1 to 9, characterized in that it consists in depositing, during the first deposition, during step (a), at least plies of continuous fibers and plies of fibers. discontinuous.

11. Aerodynamic structure, characterized in that it is produced by the method according to any one of claims 1 to 10.

12. Blade for a wind turbine, characterized in that it is produced by the method according to any one of claims 1 to 10.