MOLD FOR CURVED PANEL

Description

Domaine technique

[0001] The present invention relates to a mold for molding and polymerizing under pressure a composite material panel which is curved and of large dimension. Art antérieur

[0002] A composite material comprises one or more reinforcements impregnated with a polymerized resin.

[0003] A known mold for molding a large curved panel of composite material, for example a wing panel for an aircraft, comprises a molding surface on the one hand and a vacuum bag or membrane on the other. The pressure exerted for molding is in some cases atmospheric pressure, via the vacuum between the mold and the bag or membrane, or in other cases is increased using an autoclave, typically between 6 and 8 bars. A pressure of 6 to 8 bars is usually necessary to limit the porosity of the composite to acceptable values, typically below 2% of the volume. The mold is heated to polymerize the resin of the composite material, typically at 180°C. The permitted heating rate is generally 3°C / minute but is most often limited to 1°C / minute for autoclave curing in order to maintain thermal homogeneity across the entire mold and the part to be produced.We typically aim for a homogeneity of + / - 5°C across the whole.

[0004] Most often the resin is either already present in the reinforcement when the mold is closed by the vacuum bag or membrane, or it is injected after the vacuum is applied. In some cases the resin is partially present during the vacuum and a supplement is injected.

[0005] Furthermore, if the part incorporates projecting elements, for example stiffeners, these are generally formed upwards, opposite the molding surface, by an external device located under the vacuum bag, the positioning of which in relation to the molding surface is difficult.

[0006] An alternative to pressure and temperature curing in an autoclave on a single-sided mold sealed with a vacuum bag is a process called SQRTM - Same Qualified Resin Transfer Molding -, which is known to allow pressure and temperature curing in a double-sided male / female mold. This SQRTM process allows the reproduction of the pressure and temperature levels of an autoclave process. SQRTM allows the production of a composite of a quality at least equivalent to that of a composite produced in an autoclave.

[0007] There are many processes for injecting resin when molding a composite panel. The process is generally called RTM - Resin Transfer Molding and is available in many variations depending on whether it uses a vacuum, external pressure on the mold, a single-sided mold with a vacuum bag or a male / female mold, depending on when the mold is fully closed. Better quality parts are generally obtained in male / female molds where a vacuum is applied before pressure injection.

[0008] Using an autoclave to apply closing pressure to a mold and heat it is known to be an energy-inefficient process (it requires heating a gas that heats a mold by convection) and a consumer of accessory materials such as vacuum bags that are discarded after each use or membranes that are discarded after a few uses.

[0009] In the case of an aircraft wing panel, the reinforcement of the composite material is carbon fiber, the resin is most often an epoxy. The particularity of carbon fiber is that it expands very little during the molding cycle, between 20 ° C and 180 ° C. It is common to mold large parts on single-sided molds made of materials whose thermal expansion is close to that of carbon fiber such as Invar steel or a carbon fiber-based composite. Invar is an expensive material. A carbon fiber-based composite is relatively fragile as a material for a mold. It has been shown that during SQRTM or RTM molding of large parts, in a male / female mold, under pressure and temperature, it is possible to avoid using a mold material whose coefficient of expansion is close to that of carbon fiber. Typically, aluminum or steel molds are used.

[0010] Document CA2487697A1 describes a method of molding a thin-walled part from a curable resin material by causing adjustable portions to engage and support the engaging heads of mechanical supports at the desired locations. Résumé de l'invention

[0011] An object of the present invention is to provide a mold for a panel-type part made of a large, curved composite material, polymerized under pressure and temperature. This mold allows excellent control of the thickness of the panel and the position of any protruding elements. This mold can also be manufactured from materials whose coefficient of expansion is significantly different from that of the reinforcement of the composite part, for example steel or aluminum for carbon fiber reinforcement. The mold according to the invention allows high-quality parts to be manufactured at an attractive rate.

[0012] To this end, the invention provides a mold for molding at least a portion of a curved part, the part having a first part surface and a second part surface separated by a thickness, the mold comprising: a shell comprising: ∘ a first part comprising a first molding surface for molding the first part surface, and a first outer surface opposite the first molding surface, ∘ a second part comprising a second molding surface for molding the second part surface, and a second outer surface opposite the second molding surface, at least one of the first and second outer surfaces being non-planar; a support system comprising: ∘ a first support device mechanically coupled to the first part of the shell and configured to press on the first part of the shell in a first direction, and ∘ a second support device mechanically coupled to the second part of the shell and configured to press on the second part of the shell in the first direction;the mold being configured to allow, between the first part of the shell and the first support device, and between the second part of the shell and the second support device, sliding in at least one direction perpendicular to the first direction.;

[0013] In the mold according to the invention, each of the first and second surfaces of the part is defined by one of the molding surfaces, and the thickness of the part is defined by the distance between the molding surfaces of the mold. The mold is preferably such that sliding is possible in any direction perpendicular to the first direction.

[0014] Since the first part of the shell slides relative to the first support device and the second part of the shell slides relative to the second support device in at least one direction perpendicular to the first direction, the stress exerted by the support devices on the molding surfaces is only in the first direction. This allows the pressure to be taken up in the first direction while allowing free movement in at least one perpendicular direction. Thus, when during molding, the temperature of the molding surfaces increases and they expand, the molding surfaces are free to expand perpendicular to the first direction while being stressed in the first direction.Therefore, the thermal expansion of the molding surfaces results mainly in a deformation perpendicular to the first direction, and the thickness of the part, i.e. its extension in the first direction, is extremely well controlled despite the thermal expansion thanks to the pressure in the first direction. For example, if the first direction is vertical, we can consider that the shell slides horizontally between support devices which remain fixed horizontally. Therefore the thermal expansion of the molding surfaces results mainly in an increase in the gap between the support devices, this gap (and therefore the thickness of the part) is extremely well controlled thanks to the pressure exerted by a clamping device on the support system. During molding, the thickness of the part is thus controlled by pressing in the first direction.

[0015] During molding, the injected resin exerts pressure tending to cause the first and second parts of the shell to move apart. With the mold according to the invention, this outward pressure is mainly counteracted by a clamping device which exerts inward pressure via the support system. The balance between outward and inward pressures makes it possible to obtain the desired part thickness.

[0016] The molding is carried out at a temperature between 120°C and 180°C under a pressure of 5 to 10 bars. Typically, the vacuum level inside the shell is less than 10 mbar.

[0017] The mold is configured so that the mechanical coupling between the first support device and the first part of the shell transmits pressure in the first direction from the first support device to the first part of the shell, and so that the mechanical coupling between the second support device and the second part of the shell transmits pressure in the first direction from the second support device to the second part of the shell.

[0018] The pressure transfer and sliding between the first portion of the shell and the first bearing device occurs over a plurality of first sliding zones, and the pressure transfer and sliding between the second portion of the shell and the second bearing device occurs over a plurality of second sliding zones.

[0019] Preferably, the pressure is applied only to a portion of the outer surfaces of the first part of the shell, and of the second part of the shell, this portion representing less than 20% of the outer surface. In other words, the first sliding zones represent less than 20% of the outer surface and the second sliding zones represent less than 20% of the outer surface. This makes it possible to obtain a particularly light mold.

[0020] The shell is designed so that its first part and its second part do not slide, or only slightly, relative to each other during molding. The first part of the shell is preferably a female part and the second part is preferably a male part. However, the opposite is possible while remaining within the scope of the invention.

[0021] The non-planarity of the outer surfaces allows them to follow, at least partially, the curved shape of the casting, or of the cast part of the part. This allows the shell to be particularly light and therefore particularly easy to heat. The same applies to the non-coplanarity of the sliding zones.

[0022] SQRTM or RTM molding in a double-sided mold like the shell of the invention, under pressure and temperature, eliminates the need for an autoclave. One benefit is that the thickness of the part is better controlled than in an autoclave because it is defined by the mold gap and not by the pressure exerted by the autoclave to limit porosity. Thanks to the support system, the double-sided mold according to the invention is sufficiently stiff so that the gap does not vary excessively in response to the pressure exerted inside the mold. Another way to obtain sufficient stiffness would be to use a stiff shell as such, but such a shell is particularly massive, which increases the energy required for its heating.

[0023] The first direction is preferably such that it takes up the majority of the pressure exerted by the reinforcement and the resin on the interior of the mold during molding.

[0024] The first direction is preferably vertical, but it could be any direction (for example horizontal) while remaining within the scope of the invention. The part extends mainly in the second and third directions and its thickness extends mainly in the first direction.

[0025] The part preferably comprises a panel. The mold according to the invention is particularly suitable for parts which are or which comprise panels of at least 1 m 2< , for example at least 10 m 2< . It may have a length, measured in the second direction, of at least 5 m, for example at least 12 m. It may have a width, measured in the third direction, of at least 1 m, for example at least 2 m.

[0026] The part is curved. For example, it may have a negative curvature point, which indicates a "saddle" geometry. The hollow in the part may be at least 30 cm deep, for example at least 80 cm.

[0027] Supporting devices can be made of steel or carbon fiber, for example. Carbon fiber helps reduce mass and thermal expansion.

[0028] The first and second sliding zones preferably comprise one or more materials such that the coefficient of static friction, µs, is less than 0.5 for sliding between the first part of the shell and the first support device, and between the second part of the shell and the second support device.

[0029] According to one embodiment, the mechanical coupling between the first outer surface and the first support device comprises protrusions extending from the first outer surface towards the first support device and / or protrusions extending from the first support device towards the first outer surface; and the mechanical coupling between the second outer surface and the second support device comprises protrusions extending from the second outer surface towards the second support device and / or protrusions extending from the second support device towards the second outer surface. Thus, the contact between the support devices and the first and second parts of the shell does not extend over the entire surface of the shell. This allows the mold to be particularly light. The pressure in the first direction is transmitted via the protrusions.

[0030] According to one embodiment, at least some of the protrusions comprise ridges. This allows for a particularly homogeneous transfer of pressure. The ridges form the contact lines between the shell and the support system. In addition, the ridge-shaped protrusions of the outer surfaces allow the shell to be stiffened. However, it is possible, while remaining within the scope of the invention, for at least some of the protrusions to have another shape, for example rods or posts.

[0031] According to one embodiment, the mold comprises heating elements fixed to the first outer surface, and / or to the second outer surface, and / or to the support system, and located between protrusions. The heating elements may be, for example, electrical resistors or magnetic inductors inducing eddy currents in the shell. The arrangement of the heating elements as close as possible to the outer surfaces of the shell makes it possible to consume particularly little energy since the heat transfer is particularly efficient.

[0032] In one embodiment of the invention, the support system comprises passages configured to pass a heat transfer fluid. The fluid may for example be a gas, in particular air, passing through holes in the walls forming the protrusions. The cooling may be passive or by forced convection. The fluid may be a liquid, in particular if the mold comprises an active cooling system between the molding surfaces and the support system. The active cooling system may for example comprise pipes located between the first thermal insulation and in which the cooled liquid circulates. Cooling by gas and cooling by liquid can be combined.

[0033] According to one embodiment, the mechanical coupling between the first outer surface and the first support device and the mechanical coupling between the second outer surface and the second support device comprises a first thermal insulation. Thus, the thermal transmission between the shell and the support system is particularly low. This allows particularly little energy to be consumed since the mass of material to be heated is limited to the shell, which is light. In addition, this prevents the support system from thermally deforming. The first thermal insulation may, for example, be made of a material having a thermal conductivity of less than 0.5 W m -1< K -1< , for example, a laminated material based on glass fibers and resin such as Glastherm. It is also possible for the support devices to be made of a thermally insulating material, for example a carbon fiber composite.

[0034] According to one embodiment, the sliding between the first part of the shell and the first support device occurs on a plurality of first sliding zones and the sliding between the second part of the shell and the second support device occurs on a plurality of second sliding zones, the mold being configured so that the distance in the first direction between the first sliding zones and the second sliding zones varies by less than 20% over the entire mold. Thus, the distance in the first direction between the junction points of the shell and the support system varies by less than 20% over the entire mold.This allows for a particularly uniform application of pressure in the first direction because when the shell expands over its thickness all the sliding zones move apart in the first direction in the same way (which is taken up by the clamping device) and contact is not lost anywhere.

[0035] The distance between the shell elements is not constant throughout the mold. In fact, the thickness of the part can vary between two locations in the mold.

[0036] According to one embodiment, the first part of the shell comprises a first segment and a second segment joined by a mechanical attachment outside the first molding surface and by a weld along the first molding surface; and / or the second part of the shell comprises a first segment and a second segment joined by a mechanical attachment outside the second molding surface and by a weld along the second molding surface. Having several segments facilitates the manufacture and transport of the mold, and allows a single segment to be separated from the first part of the shell or from the second part of the shell if a modification is to be made thereto or in the event of failure of a part of the shell. The mechanical assembly, for example by bolting, allows a particularly strong and precise separable attachment. The surface weld allows the molding surface to be hermetic.The weld preferably has a maximum thickness of 10 mm. It can be done by laser. Each of the segments is preferably less than 10 meters long. The weld is broken when the segments are separated.

[0037] According to one embodiment, the shell comprises cavities in the first molding surface and / or the second molding surface. The cavities allow projecting reinforcements to be placed, which, after molding (therefore polymerization of the resin), will form projecting elements of the part, for example stiffeners.

[0038] The cavities are preferably only in the first molding surface, and the second part of the shell is devoid of them. If the first part is located below the second part, this allows the complexity to be in the first part, which is heavier but whose handling is limited during the molding process, and the second part, which is removable and subject to more handling, to be simpler and lighter.

[0039] According to one embodiment, the mold comprises removable inserts located in the cavities, each insert comprising an open space intended to receive a protruding reinforcement. With the polymerized resin, the protruding reinforcement will constitute, after molding, a protruding element of the part, typically a stiffener. The inserts may, for example, be made of the same material as the shell. They may comprise at least two parts removable from each other. The inserts facilitate the molding of the protruding elements as well as their demolding.

[0040] According to one embodiment, the mold comprises removable arms configured to carry the inserts and to be inserted, at least partially, into grooves of the first molding surface, and / or of the second molding surface. The arms make it possible to take the inserts in which are located the reinforcements which will constitute the projecting elements, stiffener or other component of the part, on the system where they were prepared while maintaining their respective positions to deposit them in the mold. This makes it possible to segment inserts which would have a significant length and to prepare them by arranging them in precise relative positions. A precise clearance between insert segments can be defined so that once positioned in the mold and brought to a given temperature, this clearance between segments disappears under the effect of the thermal expansion of the inserts, without damaging the reinforcements which are arranged there.

[0041] The arms allow for precise installation of cold inserts and the reinforcements they contain into a preheated molding surface, for example, between 90 and 120°C. A reinforcement can then be placed on the molding surface and the inserts before the other molding surface is placed. This too may have been preheated. This solution saves time in producing the part, as most of the mass to be heated has been preheated. Once the part has cured, for example to 180°C, the arms allow the part to be easily demolded and the molding device to be quickly released, which can then be used to mold another part.

[0042] The invention further provides a system comprising a mold, a clamping device, and a resin injection system configured to inject a resin between the first molding surface and the second molding surface, preferably into and / or around at least one reinforcement located between the first molding surface and the second molding surface. The at least one reinforcement comprises the main reinforcement and optionally one or more other reinforcements, for example protruding reinforcements. In the case of the RTM process, the resin is injected into the at least one reinforcement. In the SQRTM process, the resin is injected around the at least one reinforcement before polymerization to control the pressure in the resin during the molding process. The mold according to the invention is intended to operate for example with a pneumatic clamping device in which the force is transmitted by a compressed gas.The pressure is preferably applied vertically upwards by a lower part of the clamping device (as shown in the figures). The clamping device can be partly fixed to the support system or in one piece with the first support device on one side and with the second support device on the other side.

[0043] According to one embodiment, the pressure applied by the clamping device can be controlled by zones, which allows different pressure to be applied to the edges of the shell compared to the center of the shell. The pressures applied can vary during molding to facilitate resin injection and / or to obtain the desired thicknesses during polymerization of the resin.

[0044] The invention further provides a molding method comprising heating a resin and a main reinforcement in a mold according to the invention, so as to mold a composite part, integrating the main reinforcement and resin, and the first part surface of which is molded against the first molding surface and the second part surface of which is molded against the second molding surface. During heating, resin is preferentially injected between the first molding surface and the second molding surface, and pressure in the first direction is applied via the support system. The method may be, for example, resin transfer molding without prior impregnation of the reinforcement (RTM) or with prior impregnation of the reinforcement (SQRTM).The process may not include resin injection (for example, a process called "compression molding"), if the quantity of resin already present is such that the desired pressure is achieved even without injection. Heating the resin present in the reinforcement allows it to polymerize. Heating is preferably carried out by heating the shell. Heating allows, for example, a temperature between 120°C and 180°C to be reached. The pressure in particular prevents the resin from degassing, or even boiling, which would lead to an unacceptable porous part. Injection is preferably carried out under a pressure between 5 and 10 bars.

[0045] In one embodiment, the part is or comprises an aircraft wing panel, an aircraft empennage, an aircraft fuselage panel, an aircraft wing flap, an aircraft fairing, or an aircraft engine part.

[0046] According to one embodiment, the wing may comprise an upper panel manufactured in a mold according to the invention, and a lower panel manufactured in another mold according to the invention. According to another embodiment, the upper panel and the lower panel are manufactured in the same mold: the upper panel against one of the molding surfaces of the shell, and the lower panel against the other of the molding surfaces of the shell.

[0047] According to one embodiment, the method comprises, prior to the resin injection, inserting the inserts into the cavities and inserting the protruding reinforcements into the open spaces of the inserts, so that the protruding reinforcements, the main reinforcement and the resin are joined by the molding so as to form the part. The precision of the inserts and their positioning means that the protruding elements have a particularly well-defined shape.

[0048] According to one embodiment, the shell is at a temperature above 40°C, for example between 90°C and 120°C, at the time of insertion of the inserts into the cavities. For example, the shell can be maintained above 40°C, for example between 90°C and 120°C, between successive moldings. This makes it possible to reduce the amount of energy required to increase the temperature of the shell.

[0049] According to one embodiment, the heating takes place during: a period during which the pressure in the first direction is uniform across the entire shell, and at least one other period during which the pressure in the first direction over a central shell area is different from the pressure over a peripheral shell area. Brève description des figures

[0050] Other characteristics and advantages of the invention will appear on reading the detailed description which follows, for the understanding of which reference will be made to the appended figures among which: there figure 1 is a vertical schematic view of a shell, the figure 2 is a vertical schematic view of a casting system, the figure 3 is a vertical schematic view of part of a mold, the figures 4a et 4b illustrate, respectively, a first and a second support device, the figure 5 is a schematic view of an assembly between several segments of a first part and a second part of the shell, the figure 6a is a top view of a second shell part, the figure 6b is a view from below of a second part of the shell, the figure 7 is a top view of a first part of the shell, the figure 8 is a vertical view illustrating an insert in a cavity of a first part of a mold, the figure 9 is a schematic top view of projecting reinforcements and inserts, the figure 10 is a schematic top view of projecting reinforcements and inserts on a first part of the shell, the figure 11a is a schematic vertical section of projecting reinforcements and inserts on a first part of the shell, before injection, the figure 11b is a schematic vertical section of a part in a mold opening, after injection, and the figure 11c is a schematic vertical section of a casting. Modes de réalisation de l'invention

[0051] The present invention is described with particular embodiments and references to figures but the invention is not limited by them. The drawings or figures described are only schematic and are not limiting. Furthermore, the functions described may be performed by structures other than those described herein.

[0052] In the context of this document, the terms "first" and "second" serve only to differentiate between the different elements and do not imply an order between these elements.

[0053] In the figures, identical or similar elements may bear the same references.

[0054] The various elements of the invention are described with reference to a first 501, a second 502, and a third 503 direction. The second 502 and the third 503 directions are perpendicular to the first direction 501 and are preferably perpendicular to each other. The references 501, 502 and 503 are indicated in particular in the figure 8 The figures correspond to an embodiment of the invention where the first direction 501 is vertical.

[0055] There figure 1 is a vertical schematic view of a shell 2 for use in a mold 1 according to one embodiment of the invention. The shell 2 comprises a first part 10 and a second part 20. When the first direction 501 is vertical, the first part 10 and the second part 20 are essentially horizontal, and the first part 10 is intended to be below the second part 20. The first part 10 comprises a first molding surface 11, and the second part 20 comprises a second molding surface 21, which together define the shape of a part 9 ( figures 2 And 3 ) which will be molded by mold 1. Part 9, once molded, incorporates a main reinforcement 99, projecting reinforcements 93 ( figure 11a ) and polymerized resin. The main reinforcement 99 and the projecting reinforcements 93 are made of carbon fibers.

[0056] The first molding surface 11 makes it possible to mold the first part surface 91 of the part 9 and the second molding surface 21 makes it possible to mold the second part surface 92 of the part 9. The shell 2 is provided so that, around its periphery, the first part 10 and the second part 20 do not slide, or only slightly, relative to each other. For example, the friction between them at the left and right ends of the figure 1 may be sufficient to prevent slippage.

[0057] The first part 10 comprises a first outer surface 12 opposite the first molding surface 11, and the second part 20 comprises a second outer surface 22 opposite the second molding surface 21. The first outer surface 12 and / or the second outer surface 22 are non-planar so as to follow, at least partially, the curvature of the part 9. The first outer surface 12 preferably comprises facets 14 perpendicular to the first direction 501, and / or the second outer surface 22 preferably comprises facets 24 perpendicular to the first direction 501.

[0058] There figure 2 is a vertical schematic view of a molding system 100 according to one embodiment of the invention. The molding system 100 comprises a mold 1 and a clamping device 110, for example pneumatic or hydraulic, comprising tubes 101 provided to receive a fluid in order to apply pressure in the first direction 501 to the mold 1. The mold 1 comprises the shell 2, and a support system 3. The molding system 100 also preferably comprises a resin injection system 120 configured to inject a resin between the first molding surface 11 and the second molding surface 21.

[0059] The support system 3 comprises a first support device 30 configured to press in the first direction 501 on the first part 10, via first sliding zones 51, and a second support device 40 configured to press in the first direction 501 on the second part 20, via second sliding zones 52. The first sliding zones 51 are not in the same plane and / or the second sliding zones 52 are not in the same plane.

[0060] The first sliding zones allow sliding perpendicular to the first direction 501 between the first part 10 and the first support device 30, and transmit pressure in the first direction 501 from the first support device 30 to the first part 10. The second sliding zones allow sliding perpendicular to the first direction 501 between the second part 20 and the second support device 40, and transmit pressure in the first direction 501 from the second support device 40 to the second part 20.

[0061] In one embodiment of the invention, the first outer surface 12 comprises downwardly extending protrusions 13, the first support device 30 comprises upwardly extending protrusions 31, and the first sliding zones are at the interface between the protrusions 13 of the first outer surface 12 and the protrusions 31 of the first support device 30.

[0062] In one embodiment of the invention, the second outer surface 22 comprises upwardly extending protrusions 23, the second support device 40 comprises downwardly extending protrusions 41, and the second sliding zones are at the interface between the protrusions 23 of the second outer surface 22 and the protrusions 41 of the second support device 40.

[0063] Preferably, the distance along the first direction 501 between the first sliding zones and the second sliding zones varies by less than 20% over the entire mold 1.

[0064] The first support device 30 comprises a planar outer surface 39, oriented away from the shell 2, which is perpendicular to the first direction 501. The planar outer surface 39 is in contact or is integral with a first part 111 of the clamping device 110. The second support device 40 comprises a planar outer surface 49, oriented away from the shell 2, which is perpendicular to the first direction 501. The planar outer surface 49 is in contact or is integral with a second part 112 of the clamping device 110. The first part 111 of the clamping device 110 and the second part 112 of the clamping device 110 are mechanically coupled 113.

[0065] There figure 3 is a vertical schematic view of a part of a mold 1 according to an embodiment of the invention. It makes it possible to illustrate certain optional characteristics of the invention, in particular heating elements 60 located between the protuberances 13, 23 of the shell 2, a first thermal insulation 71 located at the sliding zones 51, 52, and a second thermal insulation 72 located on the heating elements 60 opposite the shell 2. The second thermal insulation 72 may be for example in a material having a thermal conductivity of less than 0.5 W m -1< K -1< , for example in glass wool.

[0066] The heating elements 60 are preferably against the external surfaces 12, 22, in particular in the case of conduction heating. The heating elements 60 are preferably facing the external surfaces 12, 22 in the case of radiative or inductive heating.

[0067] THE figures 4a et 4b illustrate, respectively, the first 30 and the second 40 support devices in an embodiment of the invention in which the protrusions 31, 41 of the support devices 30, 40 are edges. The protrusions 31, 41 form walls delimiting compartments 32, 42 or boxes. These walls are preferably crossed by holes creating passages 33, 43 between the compartments 32, 42. Such an architecture of the support devices 30, 40 allows them to be particularly light, which in particular makes it easier to handle them. This also allows the calories to be evacuated thanks to the circulating air, for example by forced convection, and thanks to a heat transfer fluid system.

[0068] Generally, it is preferred that the support devices 30, 40 are at least 50% hollow. In other words, at least 50% of the volume occupied by each of the support devices 30, 40 is not in a solid material.

[0069] There figure 5 is a schematic view of an assembly between a first 17 and a second 18 segments of the first part 10, and of an assembly between a first 27 and a second 28 segments of the second part 20 in one embodiment of the invention. Each of the assemblies comprises a mechanical fastener 58 which is located outside the molding surface 11, 21, and / or a weld 59 which is located at least on the molding surface 11, 21. The mechanical fastener 58 and the weld 59 are preferably spatially separated from each other. The mechanical fastener 58 may for example comprise flanges 16, 26 crossed by bolts. The weld 59 may have a triangular longitudinal section. The interface between the segments 17, 18 or 27, 28 may comprise a seal 57.

[0070] There figure 6a illustrates the second outer surface 22 of the second shell part 20 in one embodiment of the invention. The protrusions 23 of the second part 20 are edges. They delimit facets 24. Similarly, as appears better figure 10 , the protrusions 13 of the first part are edges which delimit facets 14. The second part 20 comprises a first 27, a second 28 and a third 29 segments which end with flanges 26 at their junctions.

[0071] There figure 6b illustrates the first molding surface 21 of the second shell part 20 in one embodiment of the invention.

[0072] There figure 7 illustrates the first molding surface 11 of the first shell part 10 in one embodiment of the invention. The first part 10 comprises a first 17, a second 18 and a third 19 segments. The periphery 15 of the part 9 is visible on the first molding surface 11. The mold 1 preferably comprises a seal 115 around the periphery 15.

[0073] In one embodiment of the invention, the shell 2 comprises cavities 81, preferably in the first molding surface 11, provided to receive, at least partially, projecting reinforcements 93 (visible figure 11a in particular). In addition or instead, it could include them in the second molding surface 21. The cavities 81 and the projecting reinforcements 93 extend in particular perpendicular to the first direction 501. They extend mainly in the second direction 502. They are not parallel. The main reinforcement 99 and the projecting reinforcements 93 are preformed: they are already shaped before their integration into the part 9 during molding.

[0074] The shell 2 preferably comprises grooves 85 of the first molding surface 11, or possibly of the second molding surface 12. The grooves 85 are intended to receive arms 84 (visible figure 10 ). The arms 84 and the grooves 85 preferably extend, at least in part, in the third direction 503.

[0075] The projecting reinforcements 93 are preferably inserted, at least partially, into open spaces 83 of inserts 82 removable relative to the shell 2, the inserts 82 themselves being at least partially inserted into the cavities 81 ( figure 8 ).

[0076] Inserts 82 can be carried by arms 84 (visible figure 10 ) inserted, at least partially, into grooves 85 of the first molding surface 11, or possibly of the second molding surface 12.

[0077] There figure 8 also illustrates that the inserts 82 are preferably at least partially inserted into the cavities 81. The inserts 82 are removable relative to the shell 2. They are preferably in two parts 82a, 82b, the open space 83 being between the two parts 82a, 82b. They are intended to carry the projecting reinforcements 93.

[0078] There figure 9 is a schematic top view of the protruding reinforcements 93 during their installation in the inserts 82. A protruding reinforcement 93 can rest on several inserts 82 separated by an intermediate space 87. The inserts 82 can then be carried by a temporary support system 86. The arms 84 pick up the inserts 82 and the protruding reinforcements 93 on the support system 86 while respecting their respective positions, and are placed on the first part 10 as illustrated figure 10 .

[0079] There figure 10 is a schematic top view of the projecting reinforcements 93 and the inserts 82 during their installation on the first part 10. The protrusions 13 in the form of ridges and the facets 14, which are on the first exterior surface 12 of the first part 10 are also represented therein.

[0080] In practice, between successive moldings of two parts 9, the shell 2 remains hot, for example around 120°-140°. The shell 2 remains at least at 40°C for example. When the arms 84 carrying the inserts 82 and the projecting reinforcements 93 are placed on the first hot part 10, the inserts 82 expand and the intermediate spaces 87 disappear.

[0081] There figure 11a is a vertical sectional view illustrating precise positioning of the main reinforcement 99, inserts 82 and projecting reinforcements 93 in the first part 10 before injection.

[0082] During injection, the main reinforcement 99 and the projecting reinforcements 93 are located in the space between the molding surfaces 11, 21 and the resin they contain and which surrounds them, which is cured so as to polymerize. The clamping device 110 applies, via the support system 3, a pressure in the first direction 501 preventing the molding surfaces 11, 21 from moving apart in the first direction 501. Under the effect of the temperature (for example 160°-180°), the molding surfaces 11, 21 expand horizontally relative to the support system 3 thanks to the sliding zones. The projecting reinforcements 93, the main reinforcement 90 and the resin are integrated into the part 9 during the polymerization of the resin.

[0083] Preferably, the heating comprises a period during which the pressure in the first direction 501 is applied uniformly to the shell 2, and at least one other period during which the pressure in the first direction 501 on a central zone of the shell 2 is different from the pressure on a peripheral zone of the shell 2. For example, during a first period, the pressure in the first direction 501 may be lower on the central zone than on the peripheral zone to facilitate injection; during a second period, the pressure in the first direction 501 may be uniform to obtain the desired shape of the part; then, during a third period, the pressure in the first direction 501 may be lower on the central zone than on the peripheral zone to avoid crushing the center of the part.In fact, during heating, when the resin begins to solidify, the part 9 shrinks and the pressure it exerts on the shell 2 decreases. The reduction in pressure of the mold 1 on the part 9, at least on the central zone of the shell 2, makes it possible to take this phenomenon into account. Maintain the perimeter 15 of the part 9 (illustrated . figure 7 ) at a higher pressure than the central area helps maintain the seal.

[0084] To allow the temporal change of the pressure on the workpiece 9, the clamping device 110 is configured to be able to change the pressure over time. To allow the spatial adjustment of the pressure on the workpiece 9, the clamping device 110 preferably comprises a central zone and a peripheral zone surrounding the central zone, such that the pressure in the central zone can be different from that in the peripheral zone.

[0085] There figure 11b illustrates part 9 when the second part 20 is lifted. The arms 84, which remained during injection, help in handling part 9 during demolding.

[0086] There figure 11c illustrates the part 9 taken from the mold 1. The part 9 comprises projecting elements 94 which are formed from the projecting reinforcements 93 and polymerized resin.

[0087] In other words, the invention relates to a mold 1 for molding a large curved part 9. The mold 1 comprises a first part 10, a second part 20, support devices 30, 40, and sliding zones located between the first part 10 and one 30 of the support devices 30, 40 and between the second part 20 and the other 40 of the support devices 30, 40. The mold 1 allows horizontal sliding of the first part 10 and the second part 20 while the support devices 30, 40 apply vertical pressure to them.

[0088] The present invention has been described in relation to specific embodiments, which are of purely illustrative value and should not be considered as limiting. In general, the present invention is not limited to the examples illustrated and / or described above. The use of the verbs “comprendre”, “include”, “comprendre”, or any other variant, as well as their conjugations, cannot in any way exclude the presence of elements other than those mentioned. The use of the indefinite article “un”, “une”, or of the definite article “le”, “la” or “l'”, to introduce an element does not exclude the presence of a plurality of these elements. The reference numbers in the claims do not limit their scope.

Claims

1. A mould (1) for moulding at least portion of a curved part (9), the part (9) having a first part surface (91) and a second part surface (92) separated by a thickness, the mould (1) comprising: • a shell (2) comprising: ∘ a first portion (10) comprising a first moulding surface (11) for moulding the first part surface (91), and a first outer surface (12) opposite the first moulding surface (11), ∘ a second portion (20) comprising a second moulding surface (21) for moulding the second part surface (92), and a second outer surface (22) opposite the second moulding surface (21), at least one of the first and second outer surfaces (12, 22) being non-planar; • a bearing system (3) comprising: ∘ a first bearing device (30) mechanically coupled to the first portion (10) and configured to press on the first portion (10) along a first direction (501), and ∘ a second bearing device (40) mechanically coupled to the second portion (20) and configured to press on the second portion (20) along the first direction (501); the mould (1) being configured to allow sliding in at least one direction perpendicular to the first direction (501) between the first portion of the shell (10) and the first bearing device (30), and between the second portion of the shell (20) and the second bearing device (40).

2. The mould according to the preceding claim, wherein the mechanical coupling between the first outer surface (12) and the first bearing device (30) comprises protrusions (13) extending from the first outer surface (12) to the first bearing device (30) and / or protrusions (31) extending from the first bearing device (30) to the first outer surface (12); and the mechanical coupling between the second outer surface (22) and the second bearing device (40) comprises protrusions (23) extending from the second outer surface (22) to the second bearing device (40) and / or protrusions (41) extending from the second bearing device (40) to the second outer surface (22).

3. The mould according to the preceding claim, wherein at least some of the protrusions (13, 23, 31,41) comprise ridges.

4. The mould according to one of claims 2 or 3, comprising heating elements (60) attached to the first outer surface (12), and / or to the second outer surface (22), and / or to the bearing system (3), and located between protrusions (13, 23, 31,41).

5. The mould according to any one of the preceding claims, wherein the bearing system (3) comprises passages (33, 43) configured to pass a heat transfer fluid.

6. The mould according to any one of the preceding claims, wherein the mechanical coupling between the first outer surface (12) and the first bearing device (30) and the mechanical coupling between the second outer surface (22) and the second bearing device (40) comprises a first thermal insulation (71).

7. The mould according to any one of the preceding claims, wherein the sliding between the first portion (10) and the first bearing device (30) occurs over a plurality of first sliding areas and the sliding between the second portion (20) and the second bearing device (40) occurs over a plurality of second sliding areas, the mould (1) being configured such that the distance along the first direction (501) between the first sliding areas and the second sliding areas varies by less than 20% over the entire mould (1).

8. The mould according to any one of the preceding claims, wherein the first portion (10) comprises a first segment (17) and a second segment (18) joined by a mechanical fastener (58) outside the first moulding surface (11) and by a weld (59) along the first moulding surface (11); and / or the second portion comprises a first segment (27) and a second segment (28) joined by a mechanical fastener (58) outside the second moulding surface (21) and by a weld (59) along the second moulding surface (21).

9. The mould according to any one of the preceding claims, wherein the shell (2) comprises cavities (81) in the first moulding surface (11) and / or the second moulding surface (21); the mould (1) comprising removable inserts (82) located in the cavities (81), each insert (82) comprising an open space (83) for receiving a projecting reinforcement (93); the mould (1) comprising removable arms (84) configured to carry the inserts (82) and to be inserted, at least partially, into grooves (85) of the first moulding surface (11), and / or of the second moulding surface (12).

10. A moulding system (100) comprising a mould (1) according to any of the preceding claims, a clamping device (110), and a resin injection system (120) configured to inject a resin between the first moulding surface (11) and the second moulding surface (21).

11. A moulding method comprising heating a resin and a main reinforcement (99) in a mould (1) according to any one of claims 1 to 9, so as to mould a composite part (9), incorporating the main reinforcement (99) and resin, and of which the first part surface (91) is moulded against the first moulding surface (11) and the second part surface (92) is moulded against the second moulding surface (21), while the resin is injected between the first moulding surface (11) and the second moulding surface (21), and pressure in the first direction (501) is applied via the bearing system (3).

12. The method according to the preceding claim, wherein the part (9) comprises an aircraft wing panel, an aircraft empennage, an aircraft fuselage panel, an aircraft wing flap, an aircraft fairing or an aircraft engine part.

13. The method according to claim 11 or 12, wherein the mould (1) is a mould according to claim 9, the method comprising, prior to the resin injection, inserting the inserts (82) into the cavities (81) and inserting the projecting reinforcements (93) into the open spaces (83), so that the projecting reinforcements (93), the main reinforcement (99) and the resin are united by the moulding so as to form the part (9).

14. The method according to the preceding claim, wherein the shell (2) is at a temperature above 40°C at the time of the insertion of the inserts (82) into the cavities (81).

15. The method according to any one of claims 11 to 14, in which the heating takes place during: • a period during which the pressure in the first direction (501) is uniform over the entire shell (2), and • at least one other period during which the pressure in the first direction (501) on a central shell zone (2) is different from the pressure on a peripheral shell zone (2).