Mould for a curved panel

Abstract

The present invention relates to a mould (1) for moulding a curved part (9) having a large dimension. The mould (1) comprises a first portion (10), a second portion (20), bearing devices (30, 40) and slide zones (51, 52) located between the first portion (10) and one (30) of the bearing devices (30, 40), and between the second portion (20) and the other (40) of the bearing devices (30, 40). The mould (1) allows the first portion (10) and the second portion (20) to slide horizontally while the bearing devices (30, 40) apply a vertical pressure thereto.

Description

Mold for curved panel technical field

[0001] The present invention relates to a mold for molding and polymerizing under pressure a large, curved composite material panel. Previous art

[0002] A composite material comprises one or more reinforcement(s) impregnated with a polymerized resin.

[0003] A typical mold for molding a large, curved panel of composite material, such as an aircraft wing panel, consists of a molding surface on one side and a vacuum bag or membrane on the other. The pressure applied for molding is sometimes atmospheric pressure, achieved by creating a vacuum between the mold and the bag or membrane, and in other cases, it is increased using an autoclave, typically to between 6 and 8 bar. A pressure of 6 to 8 bar is usually necessary to limit the porosity of the composite to acceptable levels, 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 it is most often limited to 1°C / minute for autoclave curing to maintain thermal homogeneity throughout the mold and the finished part.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 sealed with the bag or vacuum membrane, or it is injected after the vacuum has been applied. In some cases, the resin is partially present during the vacuum application, and additional resin is injected.

[0005] In addition, if the part incorporates protruding 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 relative to the molding surface is difficult.

[0006] An alternative to pressure and temperature curing in an autoclave, using a single-sided mold sealed with a vacuum bag, is a process called SQRTM – Same Qualified Resin Transfer Moulding – which is known for enabling pressure and temperature curing in a double-sided male / female mold. This SQRTM process replicates the pressure and temperature levels of an autoclave process. SQRTM produces a composite of at least equivalent quality to one produced in an autoclave.

[0007] Numerous processes exist for injecting resin during the molding of a composite panel. The process is generally called RTM – Resin Transfer Moulding – and comes 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, and depending on when the mold is completely closed. Higher quality parts are generally obtained using male / female molds where a vacuum is applied before pressure injection.

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

[0009] In the case of an aircraft wing panel, the composite material reinforcement is carbon fiber, and the resin is most often epoxy. A key characteristic of carbon fiber is its high degree of expansion. Temperatures are low during the molding cycle, between 20°C and 180°C. It is common to mold large parts using single-sided molds made of materials with a thermal expansion close to that of carbon fiber, such as Invar steel or a carbon fiber composite. Invar is an expensive material. A carbon fiber composite is relatively brittle as a mold material. It has been shown that when molding large parts using SQRTM or RTM in a male / female mold, under pressure and temperature, it is possible to eliminate the need for a mold material with a coefficient of expansion close to that of carbon fiber. Typically, aluminum or steel molds are used. Summary of the invention

[0010] One object of the present invention is to provide a mold for a large, curved, composite panel-type part, polymerized under pressure and temperature. This mold allows for excellent control of the panel thickness and the position of any protruding elements. The mold can also be made of materials with a coefficient of thermal expansion significantly different from that of the composite part's reinforcement, for example, steel or aluminum for carbon fiber reinforcement. The mold according to the invention makes it possible to manufacture high-quality parts at a significant production rate.

[0011] To this end, the invention proposes a mold for molding at least a part of a curved piece, the piece having a first surface and a second surface separated by a thickness, the mold comprising: • a shell comprising: o a first part comprising a first molding surface for molding the first surface of the part, and a first outer surface opposite the first molding surface, or 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: o 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 o 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.

[0012] 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.

[0013] 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 solely along the first direction. This allows the pressure to be absorbed along the first direction while permitting free movement in at least one other direction. perpendicular. Thus, when the temperature of the molding surfaces increases and they expand during molding, the molding surfaces are free to extend perpendicular to the first direction while being constrained along the first direction. Consequently, the thermal expansion of the molding surfaces results primarily in a deformation perpendicular to the first direction, and the thickness of the part, i.e., its extension along the first direction, is extremely well controlled despite the thermal expansion thanks to the pressure along the first direction. For example, if the first direction is vertical, the shell can be considered as sliding horizontally between support devices that remain fixed horizontally.Consequently, the thermal expansion of the molding surfaces results primarily in an increase in the gap between the support devices. This gap (and therefore the part thickness) is extremely well controlled by the pressure exerted by a clamping device on the support system. During molding, the part thickness is thus controlled by pressing in the first direction.

[0014] During molding, the injected resin exerts pressure that tends to separate the first and second halves of the shell. With the mold according to the invention, this outward pressure is primarily counteracted by a clamping device that exerts inward pressure via the support system. The balance between outward and inward pressures makes it possible to obtain the desired part thickness.

[0015] The molding process takes place 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.

[0016] 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 towards the first part of the shell, and so that 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.

[0017] Pressure transfer and sliding between the first part of the shell and the first support device occur over a plurality of first sliding zones, and pressure transfer and sliding between the second part of the shell and the second support device occur over a plurality of second sliding zones.

[0018] Preferably, pressure is applied only to a portion of the outer surfaces of the first and second parts 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 results in a particularly lightweight mold.

[0019] The shell is designed so that its first and second parts do not slip, or slip very little, against 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 reverse is possible while remaining within the scope of the invention.

[0020] The non-planarity of the external surfaces allows them to follow, at least partially, the curved shape of the molded part, or the molded portion of the part. This makes the shell particularly lightweight and therefore particularly easy to heat. The same applies to the non-coplanarity of the sliding zones.

[0021] SQRTM or RTM molding in a double-sided mold, such as the shell of the invention, under pressure and temperature, eliminates the need for an autoclave. One advantage is that the part thickness is better controlled than in an autoclave because it is defined by The air gap of the mold, and not the pressure exerted by the autoclave to limit porosity, is controlled by the support system. Thanks to this system, the double-sided mold according to the invention is sufficiently rigid so that the air gap does not vary excessively in response to the pressure exerted inside the mold. Another way to achieve sufficient rigidity would be to use a rigid shell as such, but such a shell is particularly massive, which increases the energy required for its heating.

[0022] The first direction is preferably such that it takes the majority of the pressure exerted by the reinforcement and the resin on the inside of the mold during molding.

[0023] 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 along the second and third directions, and its thickness extends mainly along the first direction.

[0024] The part preferably comprises a panel. The mold according to the invention is particularly suitable for parts that are or comprise panels of at least 1 m 2 , for example at least 10 m 2 It can have a length, measured along the second direction, of at least 5 m, for example at least 12 m. It can have a width, measured along the third direction, of at least 1 m, for example at least 2 m.

[0025] The piece is curved. It may, for example, have a negative point of curvature, indicating a "saddle" geometry. The hollow in the piece may have a depth of at least 30 cm, for example, at least 80 cm.

[0026] The support devices can be made of materials such as steel or carbon fiber. Carbon fiber reduces mass and thermal expansion.

[0027] The first and second sliding zones preferentially comprise one or more materials such that the static friction coefficient, p s , is less than 0.5 for the slip 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.

[0028] In one embodiment, the mechanical coupling between the first outer surface and the first support device comprises protrusions extending from the first outer surface to the first support device and / or protrusions extending from the first support device to 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 to the second support device and / or protrusions extending from the second support device to 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 lightweight. The pressure in the first direction is transmitted via the protrusions.

[0029] In one embodiment, at least some of the protrusions include edges. This allows for a particularly homogeneous pressure transfer. The edges form the contact lines between the shell and the support system. Furthermore, the edge-shaped protrusions on the outer surfaces stiffen the shell. 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.

[0030] According to one embodiment, the mold includes 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 can be, for example, electrical resistors or magnetic inductors inducing eddy currents in the shell. Positioning the heating elements as close as possible to the outer surfaces of the shell allows for particularly low energy consumption, since heat transfer is highly efficient.

[0031] In one embodiment of the invention, the support system includes passages configured for the flow of a heat transfer fluid. The fluid may, for example, be a gas, such as air, passing through holes in the walls that form the protrusions. Cooling may be passive or by forced convection. The fluid may also be a liquid, particularly if the mold includes an active cooling system between the molding surfaces and the support system. The active cooling system may, for example, include pipes located between the first thermal insulation layer and through which the cooled liquid circulates. Gas and liquid cooling can be combined.

[0032] In 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, includes initial thermal insulation. This results in particularly low heat transfer between the shell and the support system. Consequently, energy consumption is extremely low, as the mass of material to be heated is limited to the lightweight shell. Furthermore, this prevents thermal deformation of the support system. The initial thermal insulation can be, for example, made of a material with a thermal conductivity of less than 0.5 W / n. 1 K' 1 For example, in a laminated material based on glass fibers and resin such as Glastherm. It is also possible that the support devices are made of a thermally insulating material, for example, a carbon fiber composite.

[0033] In one embodiment, the slippage between the first part of the shell and the first support device occurs over a plurality of first slippage zones, and the slippage between the second part of the shell and the second support device occurs over a plurality of second slippage zones. The mold is configured such that the distance along the first direction between the first and second slippage zones varies by less than 20% over the entire mold. Thus, the distance along 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 along the first direction because when the shell expands along its thickness all the sliding areas move apart in the same way along the first direction (which is taken up by the clamping device) and contact is not lost anywhere.

[0034] The distance between the shell elements is not constant across the entire mold. Indeed, the thickness of the part can vary between two locations within the mold.

[0035] In one embodiment, the first part of the shell comprises a first segment and a second segment joined by a mechanical fastener off 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 fastener off the second molding surface and by a weld along the second molding surface. Having multiple segments facilitates mold manufacturing and transport, and allows a single segment of the first or second part of the shell to be separated if a modification is required or in the event of a shell part failure. Mechanical assembly, for example by bolting, allows for a particularly strong and precise separable fastening. Welding in The surface ensures that the molding surface is airtight. The weld preferably has a maximum thickness of 10 mm. It can be performed by laser. Each segment preferably has a length of less than 10 meters. The weld is broken when the segments are separated.

[0036] In one embodiment, the shell includes cavities in the first molding surface and / or the second molding surface. The cavities allow for the placement of protruding reinforcements, which, after molding (i.e., resin polymerization), will form protruding elements of the part, for example, stiffeners.

[0037] The cavities are preferentially located only in the first molding surface, while the second part of the shell is devoid of them. If the first part is situated beneath the second, this allows the complexity to be concentrated in the first part, which is heavier but requires less handling during the molding process, while the second part, which is removable and subject to more handling, is simpler and lighter.

[0038] In one embodiment, the mold includes removable inserts located in the cavities, each insert having an open space for receiving a protruding reinforcement. With the polymerized resin, the protruding reinforcement, after molding, will constitute a projecting 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 that are removable from each other. The inserts facilitate the molding of the protruding elements as well as their demolding.

[0039] In one embodiment, the mold includes removable arms configured to carry the inserts and to be inserted, at least partially, into grooves in the first molding surface and / or the second molding surface. The arms allow the inserts containing the reinforcements that will constitute the elements to be held. protruding elements, stiffeners, or other components of the part are positioned on the system where they were prepared, maintaining their respective positions for placement in the mold. This allows for segmenting inserts of significant length and preparing them by arranging them in precise relative positions. A precise gap between insert segments can be defined so that, once positioned in the mold and brought to a given temperature, this gap disappears due to the thermal expansion of the inserts, without damaging the reinforcements placed within them.

[0040] The arms allow for the precise placement of cold inserts and the reinforcements they contain in 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 positioned. This second surface can also be preheated. This solution saves time in part production, as most of the material to be heated has already been preheated. Once the part has cured, for example at 180°C, the arms allow for easy demolding and quick release of the molding device, which can then be used to mold another part.

[0041] The invention further proposes a system comprising a mold, a clamping device, and a resin injection system configured to inject resin between the first and second molding surfaces, preferably into and / or around at least one reinforcement located between the first and second molding surfaces. The at least one reinforcement includes the main reinforcement and optionally one or more other reinforcements, for example, protruding reinforcements. In 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 within the resin during the molding process. The mold according to the invention is Designed 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 from a lower part of the clamping device (as illustrated in the figures). The clamping device can be partially fixed to the support system or as a single unit with the first support system on one side and the second support system on the other.

[0042] In one embodiment, the pressure applied by the clamping device can be controlled by zones, allowing different pressure to be applied to the edges of the shell compared to the center. The applied pressures can vary during molding to facilitate resin injection and / or to achieve the desired thicknesses during resin polymerization.

[0043] The invention further proposes a molding method comprising heating a resin and a primary reinforcement in a mold according to the invention, so as to mold a composite part, incorporating the primary reinforcement and resin, the first surface of which is molded against the first molding surface and the second surface of which is molded against the second molding surface. During heating, resin is preferentially injected between the first and second molding surfaces, and pressure is applied in the first direction via the support system. The method can be, for example, resin transfer molding without pre-impregnation of the reinforcement (RTM) or with pre-impregnation of the reinforcement (SQRTM).The process may not involve resin injection (for example, a process called "compression molding") if the amount of resin already present is such that the desired pressure is achieved even without injection. Heating the resin within the reinforcement allows it to polymerize. This heating is preferably achieved by heating the shell itself. Heating allows, for example, reaching a temperature between 120°C and 180°C. Pressure helps prevent resin outgassing or even boiling, which would lead to an unacceptablely porous part. Injection is preferably carried out under a pressure between 5 and 10 bar.

[0044] According to one embodiment, the part is or includes an aircraft wing panel, an aircraft tail assembly, an aircraft fuselage panel, an aircraft wing flap, an aircraft fairing or an aircraft engine part.

[0045] In 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. In another embodiment, the upper and lower panels 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.

[0046] In one embodiment, the process comprises, prior to 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 mold to form the part. The precision of the inserts and their positioning results in the protruding elements having a particularly well-defined shape.

[0047] In one embodiment, the shell is at a temperature above 40°C, for example between 90°C and 120°C, at the time the inserts are placed in the cavities. For example, the shell can be maintained above 40°C, for example between 90°C and 120°C, between successive moldings. This reduces the amount of energy required to raise the shell's temperature.

[0048] According to one embodiment, the heating takes place during: • a period during which the pressure along the first direction is uniform over the entire shell, and • at least one other period during which the pressure along the first direction on a central shell area is different from the pressure on a peripheral shell area. Brief description of the figures

[0049] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for an understanding of which reference should be made to the attached figures, among which: - Figure 1 is a schematic vertical view of a shell, - Figure 2 is a schematic vertical view of a molding system, - Figure 3 is a schematic vertical view of part of a mold, - Figures 4a and 4b illustrate, respectively, a first and a second support device, - Figure 5 is a schematic view of an assembly between several segments of a first part and a second part of a shell, - Figure 6a is a top view of a second shell section, - Figure 6b is a view from below of a second shell section, - Figure 7 is a top view of the first part of the shell, - Figure 8 is a vertical view illustrating an insert in a cavity of the first part of a mold, - Figure 9 is a schematic top view of protruding reinforcements and inserts, - Figure 10 is a schematic top view of protruding reinforcements and inserts on the first part of the shell, - Figure 11a is a schematic vertical cross-section of protruding reinforcements and inserts on an initial section of the shell, before injection. - Figure 11b is a schematic vertical cross-section of a part in a mold opening after injection, and - Figure 11c is a schematic vertical cross-section of a molded part. Embodiments of the invention

[0050] 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 schematic only and are not limiting. Furthermore, the functions described can be performed by structures other than those described in this document.

[0051] In the context of this document, the terms "first" and "second" serve only to differentiate the different elements and do not imply any order between these elements.

[0052] In the figures, identical or analogous elements may bear the same references.

[0053] 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. References 501, 502, and 503 are shown in particular in Figure 8. The figures correspond to an embodiment of the invention in which the first direction 501 is vertical.

[0054] Figure 1 is a schematic vertical view of a shell 2 intended for use in a mold 1 according to an 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) that will be molded by the mold 1. The part 9, once molded, incorporates a main reinforcement 99, projecting reinforcements 93 (Figure 11a), and resin polymerized. The main reinforcement 99 and the protruding reinforcements 93 are made of carbon fibers.

[0055] The first molding surface 11 allows for molding the first surface 91 of part 9, and the second molding surface 21 allows for molding the second surface 92 of part 9. The shell 2 is designed so that, around its perimeter, the first part 10 and the second part 20 do not slip, or slip very little, relative to each other. For example, the friction between them at the left and right ends of Figure 1 may be sufficient to prevent slippage.

[0056] 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.

[0057] Figure 2 is a schematic vertical view of a molding system 100 according to an embodiment of the invention. The molding system 100 comprises a mold 1 and a clamping device 110, for example pneumatic or hydraulic, including tubes 101 designed to receive a fluid in order to apply pressure in the first direction 501 on the mold 1. The mold 1 includes the shell 2 and a support system 3. The molding system 100 also preferably includes a resin injection system 120 configured to inject resin between the first molding surface 11 and the second molding surface 21.

[0058] The support system 3 includes a first support device 30 configured to press along the first direction 501 on the first part 10, via first sliding zones 51, and a second support device 40 configured to press along 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.

[0059] 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 along 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 along the first direction 501 from the second support device 40 to the second part 20.

[0060] In one embodiment of the invention, the first outer surface 12 comprises downward-extending protrusions 13, the first support device 30 comprises upward-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.

[0061] In one embodiment of the invention, the second outer surface 22 comprises upward-extending protrusions 23, the second support device 40 comprises downward-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.

[0062] Preferably, the distance along the first direction 501 between the first slip zones and the second slip zones varies by less than 20% over the whole of the mold 1.

[0063] The first support device 30 comprises a flat outer surface 39, oriented opposite to the shell 2, which is perpendicular to the first direction 501. The flat outer surface 39 is in contact with, or integral with, a first part 111 of the clamping device 110. The second support device 40 comprises a flat outer surface 49, oriented opposite to the shell 2, which is perpendicular to the first direction 501. The flat outer surface 49 is in contact with, or 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.

[0064] Figure 3 is a schematic vertical view of a portion of a mold 1 according to an embodiment of the invention. It illustrates certain optional features of the invention, in particular heating elements 60 located between the protrusions 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, for example, be made of a material having a thermal conductivity of less than 0.5 W / nr 1 K' 1 , for example in glass wool.

[0065] The heating elements 60 are preferably positioned against the external surfaces 12, 22, particularly in the case of conduction heating. The heating elements 60 are preferably positioned facing the external surfaces 12, 22 in the case of radiant or inductive heating.

[0066] Figures 4a and 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 preferentially pierced by holes creating passages 33, 43 between the compartments 32, 42. This architecture of the support devices 30, 40 allows them to be particularly lightweight, which notably facilitates their handling. It also allows heat to be dissipated by circulating air, for example by forced convection, and by a heat transfer fluid system.

[0067] Generally, it is preferred that the bearing devices 30, 40 be at least 50% hollow. In other words, at least 50% of the volume occupied by each of the bearing devices 30, 40 is not in a solid material.

[0068] Figure 5 is a schematic view of an assembly between a first 17 and a second 18 segment of the first part 10, and of an assembly between a first 27 and a second 28 segment of the second part 20 in one embodiment of the invention. Each of the assemblies comprises a mechanical fastener 58 located outside the molding surface 11, 21, and / or a weld 59 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 through which bolts pass. The weld 59 may have a triangular longitudinal cross-section. The interface between the segments 17, 18 or 27, 28 may comprise a gasket 57.

[0069] Figure 6a illustrates the second outer surface 22 of the second part 20 of the shell in one embodiment of the invention. The protrusions 23 of the second part 20 are edges. They delimit facets 24. Similarly, as is more clearly shown in Figure 10, the protrusions 13 of the first part are edges that delimit facets 14. The second part 20 comprises a first 27, a second 28 and a third 29 segments which terminate with flanges 26 at their junctions.

[0070] Figure 6b illustrates the first molding surface 21 of the second part 20 of the shell in one embodiment of the invention.

[0071] Figure 7 illustrates the first molding surface 11 of the first shell portion 10 in one embodiment of the invention. The first portion 10 comprises a first 17, a second 18, and a third 19 segment. The periphery 15 of the part 9 is visible on the first molding surface 11. The mold 1 preferably includes a seal 1 15 around the periphery 15.

[0072] In one embodiment of the invention, the shell 2 comprises cavities 81, preferably in the first molding surface 11, designed to receive, at least partially, projecting reinforcements 93 (visible in particular in Figure 11a). In addition to or instead of these, it could also comprise them in the second molding surface 21. The cavities 81 and the projecting reinforcements 93 extend, in particular, perpendicularly to the first direction 501. They extend primarily along the second direction 502. They are not parallel. The main reinforcement 99 and the projecting reinforcements 93 are preformed: they are already shaped before being integrated into the part 9 during the molding process.

[0073] The shell 2 preferably includes grooves 85 in the first molding surface 11, or possibly in the second molding surface 12. The grooves 85 are intended to receive arms 84 (visible in Figure 10). The arms 84 and the grooves 85 extend preferably, at least in part, along the third direction 503.

[0074] The projecting reinforcements 93 are preferentially inserted, at least partially, into open spaces 83 of removable inserts 82 relative to the shell 2, the inserts 82 themselves being at least partially inserted into the cavities 81 (figure 8).

[0075] The inserts 82 can be carried by arms 84 (visible in figure 10) inserted, at least partially, into grooves 85 of the first molding surface 11, or possibly of the second molding surface 12.

[0076] Figure 8 also illustrates that the inserts 82 are preferably at least partially inserted into the cavities 81. The inserts 82 are removable from the shell 2. They are preferably in two parts 82a, 82b, with the open space 83 between the two parts 82a, 82b. They are designed to support the projecting reinforcements 93.

[0077] Figure 9 is a schematic top view of the projecting reinforcements 93 during their installation in the inserts 82. A projecting reinforcement 93 can rest on several inserts 82 separated by a spacer 87. The inserts 82 can then be supported by a temporary support system 86. The arms 84 retrieve the inserts 82 and the projecting reinforcements 93 from the support system 86, maintaining their respective positions, and are placed on the first part 10 as illustrated in Figure 10.

[0078] Figure 10 is a schematic top view of the protruding reinforcements 93 and inserts 82 during their installation on the first part 10. The protrusions 13 in the form of edges and the facets 14, which are on the first outer surface 12 of the first part 10 are also shown there.

[0079] In practice, between successive moldings of two parts 9, the shell 2 remains hot, for example at around 120°-140°. The shell 2 remains at least at 40°C, for example. When the arms 84 carrying the inserts 82 and the protruding reinforcements 93 are placed on the first hot part 10, the inserts 82 expand and the intercalated spaces 87 disappear.

[0080] Figure 11a is a vertical cross-sectional view illustrating precise positioning of the main reinforcement 99, inserts 82 and protruding reinforcements 93 in the first part 10 before injection.

[0081] During injection molding, 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, which is then cured to polymerize. The clamping device 110 applies pressure in the first direction 501 via the support system 3, preventing the molding surfaces 11, 21 from separating in the first direction 501. Under the effect of temperature (e.g., 160°-180°), the molding surfaces 11, 21 expand horizontally relative to the support system 3 due to the sliding zones. The projecting reinforcements 93, the main reinforcement 90, and the resin are integrated into the part 9 during the resin polymerization.

[0082] Preferably, the heating includes a period during which the pressure along the first direction 501 is applied uniformly to the shell 2, and at least one other period during which the pressure along the first direction 501 on a central area of ​​shell 2 is different from the pressure on a peripheral area of ​​shell 2. For example, during a first period, the pressure along the first direction 501 may be lower on the central area than on the peripheral area to facilitate injection; during a second period, the pressure along the first direction 501 may be uniform to obtain the desired shape of the part; then, during a third period, the pressure along the first direction 501 may be lower on the central area than on the peripheral area to avoid crushing the center of the part.Indeed, during heating, as the resin begins to solidify, part 9 shrinks and the pressure it exerts on shell 2 decreases. Reducing the pressure of mold 1 on part 9, at least in the central area of ​​shell 2, allows this phenomenon to be taken into account. Maintaining the perimeter 15 of part 9 (illustrated figure 7) at a higher pressure than the central area helps to maintain the seal.

[0083] To allow for temporal changes in the pressure on part 9, the clamping device 110 is configured to be able to change the pressure over time. To allow for spatial adjustment of the pressure on part 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.

[0084] Figure 11b illustrates part 9 when the second part 20 is lifted. The arms 84, which remained during injection, assist in handling part 9 during demolding.

[0085] Figure 11c illustrates part 9 as it comes out of mold 1. Part 9 includes protruding elements 94 which are formed from protruding reinforcements 93 and polymerized resin.

[0086] 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.

[0087] The present invention has been described in relation to specific embodiments, which are purely illustrative and should not be considered limiting. In general, the present invention is not limited to the examples illustrated and / or described above. The use of the verbs "include," "comprise," 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 use of the indefinite article "un", "une", or the definite article "le", "la", or "l'" to introduce an element does not preclude the presence of a plurality of such elements. Reference numbers in the claims do not limit their scope.

Claims

Demands 1. Mold (1) for molding at least a part 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 mold (1) comprising: • a shell (2) comprising: o a first part (10) comprising a first molding surface (11) for molding the first part surface (91), and a first outer surface (12) opposite the first molding surface (11), or a second part (20) comprising a second molding surface (21) for molding the second part surface (92), and a second outer surface (22) opposite the second molding surface (21), at least one of the first and second outer surfaces (12, 22) being non-planar; • a support system (3) comprising: o a first support device (30) mechanically coupled to the first part (10) and configured to press on the first part (10) in a first direction (501), and o a second support device (40) mechanically coupled to the second part (20) and configured to press on the second part (20) in the first direction (501); the mold (1) being configured to allow, between the first part of the shell (10) and the first support device (30), and between the second part of the shell (20) and the second support device (40), sliding in at least one direction perpendicular to the first direction (501).

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

3. Mold according to the preceding claim, in which at least some of the protrusions (13, 23, 31, 41) comprise edges.

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

5. Mold according to any one of the preceding claims, wherein the support system (3) includes passages (33, 43) configured to allow the passage of a heat transfer fluid.

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

7. Mold according to any one of the preceding claims, wherein the sliding between the first part (10) and the first support device (30) occurs over a plurality of first sliding zones and the sliding between the second part (20) and the second support device (40) occurs over a plurality of second sliding zones, the mold (1) being configured such that the distance along the first direction (501) between the first sliding zones and the second sliding zones varies by less than 20% over the whole of the mold (1).

8. Mold according to any one of the preceding claims, wherein the first part (10) comprises a first segment (17) and a second segment (18) assembled by a mechanical fastening (58) out of the first molding surface (11) and by a weld (59) along the first molding surface (11); and / or the second part comprises a first segment (27) and a second segment (28) assembled by a mechanical fastening (58) out of the second molding surface (21) and by a weld (59) along the second molding surface (21).

9. Mold according to any one of the preceding claims, wherein the shell (2) comprises cavities (81) in the first molding surface (11) and / or the second molding surface (21); the mold (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 mold (1) comprising removable arms (84) configured to carry the inserts (82) and to be inserted, at least partially, into grooves (85) in the first molding surface (11), and / or the second molding surface (12).

10. Molding system (100) comprising a mold (1) according to any one of the preceding claims, a clamping device (1 10), and a resin injection system (120) configured to inject resin between the first molding surface (11) and the second molding surface (21). 1 1. Molding method comprising heating a resin and a main reinforcement (99) in a mold (1) according to any one of claims 1 to 9, so as to mold a composite part (9), incorporating the main reinforcement (99) and resin, and having the first part surface (91) molded against the first molding surface (11) and the second part surface (92) molded against the second molding surface (21), while resin is injected between the first molding surface (11) and the second molding surface (21), and pressure along the first direction (501) is applied via the support system (3).

12. Method according to the preceding claim, wherein the part (9) comprises an aircraft wing panel, an aircraft tail assembly, an aircraft fuselage panel, an aircraft wing flap, an aircraft fairing or an aircraft engine part.

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

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

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

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