Core for molding a hollow composite profile and molding method using such a core

Abstract

The invention relates to a molding core (110) comprising a plurality of slices (111) aligned along a longitudinal direction (X) of core extension and an extraction member mechanically linking the slices together so that said slices are movable in translation along the longitudinal direction and can be brought closer together and moved further apart from each other, said slices being further configured to flex each around a transverse axis (Y) substantially orthogonal to said longitudinal direction, the core being configured to adopt: - a so-called molding configuration, in which the slices are brought closer together, so as to form together a compact core and - a so-called extraction configuration, in which said slices are successively mechanically stressed by the extraction member,so that the slices successively flex substantially around the transverse axis and are successively moved further apart from each other. Figure for the abbreviation: Figure 8,

Description

Title of the invention: Core for molding a hollow composite profile and molding method using such a core. TECHNICAL FIELD OF THE INVENTION

[0001] The field of the invention is that of composite structures and their manufacturing processes.

[0002] More specifically, the invention relates to a core for molding a hollow composite profile on, or with, a composite part.

[0003] The invention also relates to a molding device comprising such a core.

[0004] The invention also relates to a method of molding a hollow composite profile onto a composite part by means of such a molding device, itself comprising such a core.

[0005] The invention finds particular applications in the molding of stiffeners on composite skins, to form composite parts such as aircraft fuselage panels.

[0006] The invention finds applications in the technological industries of aeronautics and space, but can also find applications in the field of land or marine vehicles, or even in the building or energy industries. STATE OF THE ART

[0007] Aircraft structures, in particular aircraft fuselages, are generally made of composite skins reinforced by reinforcing elements.

[0008] For example, such reinforcing elements may be stiffeners, sometimes also called stringers, spars, or "stringers" in English terminology.

[0009] Such stiffeners may in particular themselves be made of composite material, for example of the same material as the composite skin which they are intended to reinforce.

[0010] Known stiffeners generally take the form of hollow composite profiles, that is, a long, thin element with a concave, or female, profile and a convex, or male, profile opposite the female profile. In particular, the hollow composite profile is open, meaning that it does not define a closed section but rather an open one.

[0011] Subsequently, reference is made in the presentation of the prior art and in the disclosure of the invention as well as in the detailed description to the term "stiffener", the invention which will be disclosed below being able however to be generalized to any generic hollow composite profile.

[0012] For example, the section of a stiffener may have a so-called omega (Q) profile, but may also have a U, V, L, Z or Delta shape, for example.

[0013] Fig. 1 schematically represents a generic composite panel 1, comprising a composite skin 2 and a plurality of stiffeners 3 with an omega profile, here three in number, which are molded onto the composite skin 2.

[0014] Fig. 2 schematically represents a stiffener 3 with an omega profile.

[0015] The stiffener 3 has a male profile 4, also called an external profile, and a profile female 5, also called internal profile, opposite to male profile 4.

[0016] The male profile 4 forms a convex profile while the female profile 5 forms a concave profile of the stiffener 3.

[0017] The female profile 5 is generally oriented towards the composite skin 2, as can be seen in [Fig.1].

[0018] The female profile 5 has an internal space 6, which is closed by the composite skin 2 when the stiffener 3 is attached to it.

[0019] The composite panel 1 can for example be made by a co-cooking process of the composite skin 2 and one or more composite stiffeners 3, previously preformed, i.e. preforms of composite stiffeners.

[0020] Such a method generally includes placing one or more preformed stiffeners in a mold having cavities in the shape of the male profile of a stiffener.

[0021] The stiffener may have been pre-formed beforehand according to any known technique.

[0022] The process then comprises placing a nucleus in each of the rays stiffeners, the core being in the shape of the internal space of the female profile of the stiffeners.

[0023] Then, the process includes draping the composite skin over the assembly formed by the mold, the stiffeners and the cores, with the composite skin being in contact with the stiffeners.

[0024] This step is preferably a fiber placement step, which is carried out under pressure to ensure the cohesion of the successive layers of fibers constituting the composite skin, as well as the cohesion between the composite skin and the stiffeners. This pressure can be provided by an elastomer roller that supports the fibers to be deposited.

[0025] During this step, pressure is also applied to the cores, which must have sufficient rigidity for this purpose.

[0026] The assembly formed by the mold, the stiffeners, the cores, and the composite skin is then placed under vacuum, for example using a vacuum bag.

[0027] The vacuum-sealed assembly is cooked by simultaneous cooking (also called co-cooking) in an autoclave.

[0028] The cores are then demolded and extracted from the composite panel thus formed.

[0029] Demolding and extracting the cores is a step presenting a significant number of technical difficulties.

[0030] Indeed, the significant frictional effort between the stiffeners and the cores opposes the extraction of the latter from the stiffeners.

[0031] This effort is increased due to the elongated nature of the stiffeners, which is synonymous with a large friction surface between the stiffeners and the cores.

[0032] This effort is also increased when the panel has a curvature, in one plane, or even in two planes.

[0033] Finally, this effort is increased when the composite skin has local variations in thickness, which can locally increase the friction effort.

[0034] In order to overcome this drawback, several variants of kernels are known from the art.

[0035] On the one hand, fusible cores are known in particular, especially those made of a metallic material having a melting point significantly higher than the cooking temperature of the composite.

[0036] During the autoclave cooking process, the metal remains in solid form, and the core is rigid.

[0037] After cooking, the assembly is immersed in a bath at the melting temperature of the metallic material, which becomes liquid and can be recovered.

[0038] For example, the fusible core can be made of lead-bismuth alloy.

[0039] On the other hand, soluble nuclei are known in particular, which are soluble in water or destructible by means of water pressure.

[0040] Finally, silicone cores are also known, with sufficient rigidity and hardness to withstand pressure during the draping step, but low enough for the core to be properly extracted from the stiffener.

[0041] However, these solutions have drawbacks and are not entirely satisfactory.

[0042] Fusible and soluble cores have the disadvantage of a different expansion of the core on the one hand and of the stiffener on the other hand during cooking, due to the difference in material between the core and the stiffener.

[0043] This can lead to the introduction of mechanical stresses in the composite structure resulting from the process, and also to local cracking in the part.

[0044] Furthermore, soaking in a bath to remove the core limits the size of composite parts that can be obtained by these processes.

[0045] In an industrial setting, the dimensions of bath tanks do not allow the soaking of large structures.

[0046] Silicone cores, with constant mechanical properties during the process, have the disadvantage of being neither particularly rigid nor particularly flexible.

[0047] Thus, the silicone cores exhibit only average rigidity while being difficult to extract from the stiffeners, particularly when the latter are elongated in length.

[0048] There is therefore a need for a molding process for composite parts with cores that exhibit both excellent rigidity, i.e., resistance to pressure, and that can be easily extracted during demolding. Description of the invention

[0049] The present invention aims to remedy all or part of the disadvantages of the prior art mentioned above.

[0050] To this end, the invention relates to a core for molding a hollow composite profile onto a composite part, comprising a plurality of slices aligned along a longitudinal direction of core extension and an extraction member mechanically linking the slices together so that said slices are movable in translation along the longitudinal direction and can be brought closer together and moved further apart from each other, said slices being further configured to flex each around a transverse axis substantially orthogonal to said longitudinal direction, the core being configured to adopt: - a so-called molding configuration, in which the slices are brought close together to form a compact core configured to be placed in the hollow composite profile for molding onto the composite part; and - an extraction configuration, in which the slices are successively mechanically stressed along the longitudinal direction by the extraction device, so that the slices successively bend substantially around the transverse axis and are successively moved apart from each other along the longitudinal direction, by which means the slices can be progressively extracted from the hollow composite profile along the longitudinal direction, following the molding of the preformed hollow composite profile on the composite part.

[0051] The design of the core in the form of a stack of translationally mobile and flexible slices makes it possible both to achieve such extraction involving less effort, while making it possible to form a core that is sufficiently rigid and compact in the molding configuration.

[0052] Thus, the core according to the invention makes it possible to create large composite structures, the extraction of a particularly long core being possible in the extraction configuration, while requiring only limited mechanical effort during extraction.

[0053] The core allows in particular the production of composite structures with significant curvatures, in one or more planes, while allowing easy extraction of the core after molding.

[0054] Moreover, the core, in its molding configuration, exhibits mechanical properties, in particular resistance to pressure, at least equivalent to known techniques, for example of soluble or fusible cores.

[0055] In addition, the core according to the invention is fully reusable after a molding cycle, by simply putting it into molding configuration.

[0056] Particularly advantageous characteristics of the core according to the invention are presented below.

[0057] - Each slice comprises a first portion and a second portion which are articulated with each other, so that said portions can fold towards each other when the slice is mechanically stressed along the longitudinal direction.

[0058] In such an embodiment, the slices flex by bending around an articulation axis substantially transverse to the longitudinal direction.

[0059] - Each slice includes a hinge by which the first portion and the second portion are articulated with each other, the hinge extending in the direction of said transverse axis of each slice.

[0060] In such an embodiment, the portions can pivot relative to each other, and the slice can flex by folding the portions towards each other.

[0061] - The slices each comprise a portion of reduced thickness between their first portion and their second portion, forming a flexible joint in the direction of said transverse axis of each slice.

[0062] In such an embodiment, the reduced thickness portion forms a material hinge, the slice can also be made in one piece.

[0063] - The slices are each formed by a plate that is in one piece of substantially constant thickness and which is flexible, so that the slices can flex around the transverse axis when mechanically stressed along the longitudinal direction of each slice.

[0064] In such an embodiment, the slice has intrinsic flexibility, which can be obtained in particular by a sufficiently low thickness and / or a substantially soft and flexible constituent material, such as a thermoplastic elastomer, for example Santoprene (registered trademark), so that the slice can flex around the transverse axis.

[0065] - The extraction member is configured to be subjected to tensile stress in the direction longitudinal.

[0066] - The extraction member comprises a mechanically secured strip of material at intervals between slices.

[0067] For example, the material strip can be a woven strip made of glass fibers.

[0068] Interval bonding means that the slices are bonded locally to the strip so that they are separated from each other when the strip is stretched, and brought together when the strip is folded, in particular accordion-style, between each of the slices.

[0069] - The extraction member comprises a strip of material having organs support brackets arranged at intervals on the strip of material and which are each configured to bear on a slice to drive it in motion along the longitudinal direction when the strip of material is stressed in tension along the longitudinal direction.

[0070] For example, the material strip can be a woven fiberglass strip, and the support members can be overmolded onto the material strip and be formed by support washers.

[0071] - The core further comprises a compaction element configured to maintain and / or compress the slices against each other in the molding configuration.

[0072] Such a device makes it possible to keep the core in the molding position, with the slices held firmly against each other.

[0073] - The core further comprises a head heel and a tail heel, arranged on either side and on the other hand of the plurality of aligned slices, and the compaction member comprising a strip of material mechanically attached to the head heel and passing through the plurality of slices as well as the tail heel, and the tail heel preferably comprising a locking member configured to lock the strip of material in position.

[0074] According to an alternative, the compacting element can be attached to a first of the slices of the plurality of slices, without the core having a head heel and / or tail heel.

[0075] - The slices are similar to each other and each has a first face and a second face opposite the first face, by which the slices are configured to come into contact with each other, said first face being convex, preferably in the form of a convex spherical portion, and said second face also being convex, preferably in the form of a convex spherical portion, or concave, preferably in the form of a concave spherical portion.

[0076] This results in a core with identical or similar slices, which are either in contact by pairs of convex faces, or by pairs of concave and convex faces.

[0077] This makes it possible to design a core with slices that are "articulated" with each other when brought together, and which allows the molding of composite structures with strong curvatures.

[0078] - The plurality of slices includes so-called even slices and so-called odd, aligned alternately along the longitudinal direction, and each comprising a first face and a second face opposite the first face, by which the slices are configured to come into contact with each other, said first face and second face of the odd slices being convex, preferably in the form of a convex spherical portion, and said first face and second face of the even slices being concave, preferably in the form of a concave spherical portion.

[0079] This makes it possible to design a core with slices that are "articulated" with each other when brought together, and which allows the molding of composite structures with strong curvatures.

[0080] - The slices further each include at least one transfer opening of pressure, extending along the longitudinal direction, the pressure transfer openings of the plurality of slices being opposite each other in the molding configuration, and the slices each comprising at least one pressure distribution opening, communicating with at least one pressure transfer opening and extending transversely to the longitudinal direction.

[0081] This allows the pressure to be distributed during an autoclave co-cooking step during molding, so that the pressure is applied also inside the hollow composite profile.

[0082] - The core further comprises a tubular vacuum bag, in which is arranged the plurality of slices.

[0083] This allows for a particularly efficient autoclave co-cooking step, and also helps to preserve the core from deterioration.

[0084] According to a second aspect, the invention relates to a molding device, comprising a mold having at least one cavity configured to receive a hollow composite profile, and at least one core as described above, configured to be disposed in the hollow composite profile.

[0085] Such a device may also include a vacuum bag, and / or cooking means, and / or an additive manufacturing system for placing composite fibers.

[0086] According to a third aspect, the invention relates to a method for molding a hollow composite profile onto a composite part using a molding device as described above, comprising the following steps: - a step of placing a preformed hollow composite profile, that is to say a preform of a hollow composite profile, into a mold cavity, the profile hollow composite being preferably a composite stiffener; - a step of positioning a core in the hollow composite profile, the core being in its molding configuration; - a draping step of the assembly comprising the hollow composite profile and the core with the composite part, the composite part preferably being a composite skin; - a co-cooking step of the assembly including the hollow composite profile, the core with the composite part and the composite part; - a core extraction step out of the hollow composite profile, in which the core is moved from its molding configuration to its extraction configuration by mechanical stressing of the extraction member in the longitudinal direction; the extraction step being implemented either after the co-baking step, or after the draping step and before the co-baking step.

[0087] It should be specified that the core according to the invention is also suitable for any use in a manufacturing process for a composite structure, or other than composite, and in particular different from the process described above. BRIEF DESCRIPTION OF THE FIGURES

[0088] Other advantages, purposes and particular features of the present invention will become apparent from the following non-limiting description of at least one particular embodiment of the devices and methods of the present invention, with reference to the accompanying drawings, in which: • [Fig.1] is a schematic view of a composite panel comprising a composite skin and a plurality of stiffeners; • [Fig. 2] is a schematic view of the profile of a stiffener exhibiting a omega profile, bonded to a composite skin; • [Fig.3] is a schematic and perspective view of a molding device during a first step of a molding process of a composite stiffener on a composite skin; • Fig. 4 is similar to Fig. 3 and illustrates the molding device during of a second stage of the molding process, using a molding core according to the invention; • [Fig.5] is similar to figures 3 and 4, and illustrates the molding device during a third stage of the molding process, specifically after the deposit of the composite skin fibers; • [Fig.6] is a detailed cross-sectional view of the molding device during the third stage of the molding process; • Figure [7] schematically represents, according to a longitudinal cross-sectional view the molding core according to a first embodiment, the core being in a molding configuration; • [Fig.8] is a detailed view, according to a longitudinal section view, of the molding core of [Fig.7], the core being in an extraction configuration; • [Fig.9] is a detailed perspective view of a slice of the core of [Fig.7] and [Fig.8]; • [Fig. 10] schematically represents, in a longitudinal cross-section, the molding core according to a second embodiment, the core being in a molding configuration; • [Fig. 11] is similar to [Fig. 10], the kernel being in an extraction configuration; • [Fig. 12] is a detailed perspective view of a slice of the core of [Fig. 10] and [Fig. 11]; • [Fig. 13] schematically represents an organ for extracting the nucleus of [Fig. 10] and [Fig. 11], taken in isolation; • [Fig. 14] is a block diagram of a molding process according to the invention, implemented by means of a molding device according to the invention. DETAILED DESCRIPTION OF THE INVENTION

[0089] The present description is given by way of non-limiting grammar, each feature of an embodiment being able to be advantageously combined with any other feature of any other embodiment.

[0090] It should be noted from the outset that the figures are not necessarily to scale.

[0091] The invention relates to the realization of a composite structure comprising a composite part and a preformed hollow composite profile which is molded onto the composite part.

[0092] The composite structure may be a composite panel, for example of an aircraft fuselage, and the preformed hollow composite profile may be a composite stiffener, for example having an omega profile, without this example being limiting.

[0093] The [Fig.1] described above illustrates such a generic composite panel 1, comprising a composite skin 2 and a plurality of stiffeners 3, here three in number; and the [Fig.2] described above illustrates a generic stiffener 3 having an omega profile.

[0094] The composite panel 1, and more generally any other type of composite structure, can be made by means of a molding device 100 according to the invention.

[0095] Figures [Fig. 3], [Fig. 4], and [Fig. 5] schematically and in perspective illustrate the device 100 at different stages of a molding process of a composite stiffener 3 on a composite skin 2, as described below.

[0096] Fig. 6 is a detailed cross-sectional view of device 100 at the stage illustrated in Fig. 5.

[0097] The device 100 includes a mold 105 having an outer surface 106 in the shape of the composite skin 2, and at least one cavity 107 having a female profile corresponding to the shape of the male profile 4 of a stiffener 3, which is here of the omega type without such a shape being limiting.

[0098] Here, the mold 105 includes three cavities 107 without this number being limiting.

[0099] The impressions 107 are elongated in length along a longitudinal extension direction and are here substantially straight, but can also be curved along their extension direction.

[0100] In the illustrated example, the outer surface 106 of the mold 105 is substantially curved, and exhibits a curvature in a plane transverse to the direction of extension of the cavities 107.

[0101] The cavities 107 are configured to each receive a preformed composite stiffener 3, which can be obtained by any known preforming technique.

[0102] The device 100 further includes at least one molding core 110, and here three cores 110 in the illustrated example.

[0103] More generally, the number of cores 110 corresponds to the number of cavities 107 in the mold 105.

[0104] Each core 110 is elongated in length and extending along a longitudinal direction X of extension, which can be straight or curved.

[0105] For example, the length of a core 110 is on the order of 10 to 20 meters, for example 15 meters.

[0106] Each core 110 is configured to be arranged inside the stiffener 3, in contact with the female profile 5 of the stiffener 3.

[0107] The core 110 has a profile corresponding to the profile of the interior space 6 of the stiffener 3, and is here generally trapezoidal in shape.

[0108] The assembly formed by the mold 105, the stiffener(s) 3, and the core(s) 110 is configured to be draped by the composite skin 2, which covers the stiffener(s) 3 and the core(s) 110, as illustrated in Figures 5 and 6.

[0109] The device 100 may further include a means for vacuum-sealing (not shown) the assembly formed by the mold 105, the stiffener(s) 3, the core(s) 110 and the composite skin 2.

[0110] For example, the means of vacuum sealing is a vacuum bag.

[0111] The device may further include a cooking means (not shown), for autoclaving the assembly under vacuum.

[0112] As shown in [Fig.7], which shows a longitudinal cross-sectional view of a core 110 of the device 100 according to a first embodiment, the core 110 comprises a plurality of aligned "vertebrae" or slices 111, along the longitudinal direction X of the core 110.

[0113] Each of the slices 111 has a first face and a second face opposite to the first face, by which the slices 111 are configured to come into contact with each other.

[0114] The slices 111 here have a general plate shape, of substantially constant thickness, each extending in a plane orthogonal to the longitudinal direction X. In particular, the thickness of the slices 111 is sufficiently small to allow the creation of cores 110 exhibiting longitudinal curvature, in one plane or even in two planes.

[0115] The slices 111 together form a stack of slices, also referred to hereafter as a "spine" or column of slices.

[0116] In particular, the core 110 may include a head heel 112 and a tail heel 113, which are arranged on either side of the stack of slices 111. The head heel 112 and the tail heel 113 may be substantially different from the slices 111, and in particular may have a substantially domed shape and / or be thicker than the slices 111.

[0117] The core 110 can adopt a molding configuration, in which the slices 111 of the column are brought closer together along the longitudinal direction X.

[0118] In particular, in this configuration, each of the slices 111 is in direct contact with its neighboring slices 111.

[0119] Fig. 7 represents the core 110 in the molding configuration, with the slices 111 shown slightly spaced apart for readability of the figure.

[0120] In the molding configuration, the slices 111 form a compact and substantially rigid core, which is suitable for molding the stiffener 3 onto the composite skin 2.

[0121] The slices 111 are each made of a material sufficiently rigid to form a molding core, in particular to ensure sufficient back pressure during the draping of the composite part, which may be a composite skin 2.

[0122] For example, the slices 111 are made of thermoplastic material, which also allows the slices 111 to be manufactured by molding in large quantities, in an economical way.

[0123] The core 110 can further adopt an extraction configuration, shown in detail in [Fig.8], in which at least part of the slices 111 are spaced apart from each other.

[0124] Furthermore, in this configuration, the slices 111 flex around a transverse direction Y, substantially orthogonal locally to the longitudinal direction X of core extension.

[0125] Thus, the slices 111 can be moved along the longitudinal direction X substantially without effort, allowing the extraction of the core 110.

[0126] On [Fig.8], a first of the slices 111 is moved along the longitudinal direction X and is located away from the other slices 111 which are still in contact with each other on this figure.

[0127] The core 110 includes an extraction member 125 mechanically linking the slices 111 to each other, so that the slices 111 can be brought closer together and moved further apart, i.e. they are mobile in translation relative to each other.

[0128] The extraction member 125 is configured to allow the core 110 to pass from the molding configuration to the extraction configuration, by mechanical stressing of the extraction member 125.

[0129] The extraction member 125 allows the progressive extraction of the slices 111 from the stiffener 3, after molding. In other words, thanks to the extraction member 125, the slices 111 can be pulled out of the stiffener 3 in a continuous sequence.

[0130] In particular, the extraction member 125 can be a traction element.

[0131] In the illustrated example, the extraction member 125 is formed by a first band 126 of matter.

[0132] The traction element can however also be formed by a cable, a chain, an articulated rod, a braid, etc.

[0133] In the first illustrated embodiment, the first strip 126 is mechanically secured to each of the slices 111, for example by means of a pivot joint substantially orthogonal to the longitudinal direction X.

[0134] The slices 111 are mechanically attached to the first band 126 at intervals, in particular at regular intervals.

[0135] Thus, when the first band 126 is stretched, the slices 111 are spaced apart from each other and can each be moved in translation along the longitudinal direction X.

[0136] When the core 110 is in the molding configuration, i.e. when the slices 111 are in contact with each other, the first strip 126 can be folded back on itself.

[0137] For this purpose, each of the slices 111 may include a housing 114 in which the first strip 126 can be housed in the molding configuration.

[0138] The core 110 may further include a compaction element 130, configured to hold the slices 111 against each other in the longitudinal direction student X.

[0139] For example, the compaction element 130 is a traction element.

[0140] In the illustrated example, the compaction element 130 is formed by a second strip 131 of material.

[0141] The traction element can however also be formed by a cable, a chain, a rod, a braid, etc.

[0142] In the first illustrated embodiment, the second strip 131 is mechanically attached to the head heel 112, and passes through the entire column of slices 111 as well as the tail heel 113.

[0143] For this purpose, the slices 111, as well as the tail stub 113 where applicable, can each be provided with a passage opening 115, through which the second strip 131 can pass.

[0144] The tail heel 113 may include a locking member 132, configured to lock the second band 131 in position, in particular to maintain a compressive force exerted on the slices 111 by the tightening of the second band 131.

[0145] In order to be able to bend, the slices 111 have a deformation capacity in a plane substantially orthogonal to the longitudinal direction X.

[0146] More specifically, the slices 111 are configured to flex each around the transverse axis Y of each slice 111, which is substantially orthogonal (at least locally) to the longitudinal direction X of the core 110, when they are mechanically stressed along the longitudinal direction X.

[0147] By "flex" is meant the fact that the slices 111 bend or fold, this may include in particular a sharp bend for example by means of a joint, or a general bending of the slice, for example due to the intrinsic elasticity of the slice 111, or a combination of these examples.

[0148] Figure 9 illustrates in perspective a slice 111 according to the first method of rea reading, taken in isolation.

[0149] The slice 111 comprises a first portion 116 and a second portion 117, which are articulated with each other.

[0150] In particular, the slice 111 here includes a hinge 118 comprising a hinge pin 119.

[0151] Here, the hinge axis 119 also forms the pivot link between the slice 111 and the first band 126.

[0152] The hinge 118 is here unidirectionally articulated, that is to say that the first portion 116 and second portion 117 can only be folded towards each other in one direction along the longitudinal direction X.

[0153] In particular, folding the first portion 116 and the second portion 117 towards each other is only possible here in the opposite direction to the direction of extraction along the longitudinal direction X, and the first portion 116 and the second portion 117 remain substantially aligned in the same transverse plane when subjected to stress in the opposite direction to the direction of extraction.

[0154] For this purpose, the second portion 117 may include one or more stop lugs 120 extending beyond the hinge 118, and bearing on the first portion 116 when the first portion 116 and second portion 117 are substantially aligned in the same plane.

[0155] According to an alternative, the hinge 118 can also be formed by a local thinning of material from the slice 111.

[0156] Figures 10 and 11 show the core 110 according to a second embodiment, respectively in the molding configuration and in the extraction configuration.

[0157] Fig. 12 illustrates a slice 111 according to the second embodiment, taken in isolation.

[0158] In the second embodiment, the slices 111 are in one piece.

[0159] The slices 111 are here deformable due to their intrinsic flexibility in a plane substantially orthogonal to the longitudinal direction X.

[0160] For example, for this purpose, the slices 111 are made of elastomeric material, preferably thermoplastic elastomer, for example Santoprene (registered trademark).

[0161] Fig. 13 schematically illustrates the first band 126 according to the second embodiment.

[0162] The first band 126 here includes support members configured to bear on the slices 111 to drive them in translation along the longitudinal direction X, when a tensile force is exerted on the first band 126.

[0163] The support members are formed at intervals, in particular at regular intervals, on the first strip 126

[0164] For example, the support members are formed by support washers 127, which can be overmolded onto the first strip 126.

[0165] The slices 111 may include a passage opening 121 through which the first strip 126 may pass.

[0166] The slices 111 may also include a housing 122 configured to receive a support washer 127.

[0167] Furthermore, in the second embodiment, the slices 111 include pressure transfer openings 123, extending substantially along the longitudinal direction X, and pressure distribution openings 124, extending substantially transversely to the longitudinal direction X.

[0168] The pressure transfer openings 123 of the plurality of slices 111 are substantially opposite each other in the molding configuration, and form together a single opening axially traversing the stack of slices 111.

[0169] The pressure transfer openings 123 and the pressure distribution openings 124 communicate, that is to say they are fluidly connected.

[0170] The pressure distribution openings 124 open onto the perimeter of each slice 111.

[0171] The pressure transfer openings 123 and the pressure distribution openings 124 together form an autoclave pressure distribution network.

[0172] It should be noted that in the first embodiment, the slices 111 may also include such openings 123 and 124.

[0173] Regardless of the embodiment considered, the core 110 may include a tubular vacuum bag 140, forming a tube in which the stack of slices 111 is arranged.

[0174] In particular, when the slices 111 have pressure transfer openings 123 and pressure distribution openings 124, the autoclave pressure can thus be applied to the female profile 5 of the stiffener 3.

[0175] Unlike the first embodiment illustrated, the core 110 here does not include a compaction member 130, although it may include such a compaction member 130, for example similar or identical to that described in connection with the first embodiment.

[0176] Unlike the first embodiment illustrated, the core 110 does not include a head heel 112 or a tail heel 113, although it may include such head heel 112 and / or tail heel 113, for example similar or identical to those described in connection with the first embodiment.

[0177] In the illustrated examples, the slices 111 have a first face and a second face which are substantially flat.

[0178] According to an example of an embodiment not shown, the slices 111 may however also have a first face and a second face which are not substantially flat.

[0179] For example, the slices 111 may have a first face and a second face each convex, preferably in the form of a cylindrical or spherical convex portion.

[0180] According to another example, the slices 111 may have a first convex face, preferably in the form of a cylindrical or spherical convex portion, and a second concave face, preferably in the form of a cylindrical or spherical concave portion, the first and second faces of two adjacent slices being configured to come into contact with each other respectively.

[0181] In addition, in the illustrated examples, the slices 111 are substantially identical or similar.

[0182] According to an example of an embodiment not shown, the plurality of slices 111 includes slices 111 called even and slices 111 called odd, aligned alternately along the longitudinal direction X, presenting different faces.

[0183] In particular, the first face and second face of the odd slices 111 may be convex, preferably in the form of a convex cylindrical or spherical portion, and the first face and second face of the even slices 111 may be concave, preferably in the form of a convex cylindrical or spherical portion.

[0184] The composite panel 1 of [Fig. 1], and more generally any generic composite structure, can be obtained by means of a molding process 200, illustrated by the block diagram of [Fig. 14].

[0185] The molding process 200 can in particular be implemented by means of a molding device 100 according to the invention, as illustrated in Figures 3 to 6 at different stages of the molding process 200.

[0186] The process 200 includes a step 205 of supplying a mold 105 having cavities 107 in the shape of the male profile 4 of a stiffener 3, as illustrated in particular in [Fig.3].

[0187] The process 200 then includes a step 210 of supplying at least one preformed composite stiffener 3, i.e., a composite stiffener preform. Such a stiffener preform may have been obtained by any manufacturing process known to the art.

[0188] The process 200 then includes a step 215 of placing at least one preformed composite stiffener 3 in the mold 105, with the male profile 4 coming into contact with the cavities 107, as illustrated in [Fig.4].

[0189] Then, the method 200 includes a step 220 of positioning a core 110 in each preformed composite stiffener 3, so that the core 110 is then placed in the interior space 6 in contact with the female profile 5 of the stiffener 3.

[0190] The core 110 is in its molding configuration during this step, with the slices 111 which are brought together and in particular in contact with each other.

[0191] For example, for this purpose, the compaction element 130 can be used to compact the core 110 when the core includes such an element. In particular, the second strip 131 can be subjected to tension and then locked in position by means of the locking element 132.

[0192] The process 200 then includes a step 225 of draping the assembly comprising at least one stiffener 3 and the core(s) 110, with a composite part, which is for example a composite skin 2.

[0193] In particular, draping step 225 is a fiber placement step, during which the fibers of a reinforcement of a semi-finished composite material are deposited on the outer surface 106 of the mold 105, as well as on the assembly including at least one stiffener 3 and the core(s) 110.

[0194] For example, draping step 225 includes the deposition of fibers by a fiber placement head that is part of an additive manufacturing system. During this step, the fiber placement head exerts significant local pressure on the mold 105 and on the cores 110.

[0195] According to one variant, device 100 may itself include such an additive manufacturing system.

[0196] Figures 5 and 6 illustrate device 100 after draping step 225.

[0197] Next, according to a first variant of the process 200, the process 200 includes a step 230 of extracting the core 110 out of the stiffener 3.

[0198] During extraction step 230, the core 110 was moved from its molding configuration to its extraction configuration.

[0199] For this purpose, the extraction member 125 is mechanically stressed, for example in tension in the first and second embodiments illustrated.

[0200] The first strip 126 is pulled along the longitudinal direction X, which has the effect of exerting a tension on the first of the slices 111. This causes the first slice 111 to bend, for example either by folding around the hinge 119 as in the first embodiment ([Fig.8]) or by bending the slice in one piece as in the second embodiment ([Fig.11]), which has the effect that the first of the slices 111 can be moved along the longitudinal direction X, substantially without effort once bent.

[0201] The first slice 111 moves along the longitudinal direction X, until the portion of the first band 126 located between the first of the slices 111 and the second of the slices 111 is stretched, and in turn causes the second of the slices 111 to bend, then move along the longitudinal direction X, and so on (see [Fig. 11] which illustrates the first three of the slices 111 which are thus driven).

[0202] The slices 111 are thus progressively extracted from the stiffener 3 along the longitudinal direction X, in a chain.

[0203] When the entire plurality of slices 111 has been extracted from the stiffener, the tubular vacuum bag 140 remains in contact with the inner profile of the stiffener in order to allow the pressure from the autoclave to be transferred during the co-curing of the composite skin-stiffener assembly.

[0204] The core 110 can then be reused, by being placed back in its molding configuration

[0205] The process 200 then includes a step 235 of co-baking the assembly comprising at least one stiffener, the core(s) 110 and the composite skin 2.

[0206] During this co-curing step, the composite fibers of the stiffener(s) 3 and of the composite skin 2 are bonded and joined together.

[0207] The co-cooking step 235 is preferably an autoclave cooking step, i.e., under pressure. For this purpose, the assembly can be placed in a vacuum bag.

[0208] During this step, the openings 123 and 124 of the slices 111 ensure pressurization of the inside of the stiffener 3.

[0209] According to a second alternative, the process includes step 230 of extraction following step 235 of co-cooking, rather than following step 225 of draping and before step 235 of co-cooking.

[0210] In such a case, the core 110 advantageously comprises a tubular vacuum bag 140.

[0211] It is more generally recalled that the invention is not limited to the examples described and illustrated.

[0212] In particular, the core according to the invention can be implemented for any type of manufacturing process other than composite molding, in which a rigid molding core is used.

Claims

Demands

1. Core (110) for molding a hollow composite profile onto a composite part, characterized in that the core comprises a plurality of slices (111) aligned along a longitudinal direction (X) of core extension and an extraction member (125) mechanically connecting the slices together so that said slices are movable in translation along the longitudinal direction and can be brought closer together and moved further apart from each other, said slices being further configured to flex each around a transverse axis (Y) substantially orthogonal to said longitudinal direction, and in that the core (110) is configured to adopt: - a so-called molding configuration, in which the slices (111) are brought closer together, so as to form together a compact core configured to be disposed in the hollow composite profile for the purpose of its molding onto the composite part;and - an extraction configuration, in which said slices (111) are successively mechanically stressed along the longitudinal direction by the extraction member, so that the slices successively flex substantially around the transverse axis and are successively moved apart from each other along the longitudinal direction (X), by means of which the slices can be progressively extracted from the hollow composite profile along the longitudinal direction, following the molding of the preformed hollow composite profile onto the composite part.;

2. Core (110) according to claim 1, wherein the slices (111) each comprise a first portion (116) and a second portion (117) which are articulated to each other, so that said portions can fold towards each other when the slice is mechanically stressed in the longitudinal direction.

3. Core (110) according to claim 2, wherein the slices (111) each comprise a hinge (118) by which the first portion (116) and the second portion (117) are articulated to each other, the hinge extending in the direction of said transverse axis of each slice.

4. Core (110) according to claim 2, wherein the slices (111) each comprise a portion of reduced thickness between their first portion and their second portion, forming a joint flexible in the direction of said transverse axis of each slice.

5. Core (110) according to claim 1, wherein the slices (111) are each formed by a plate which is of a single piece of substantially constant thickness and which is flexible, so that the slices can flex around the transverse axis when mechanically stressed along the longitudinal direction of each slice.

6. Core (110) according to any one of claims 1 to 5, wherein the extraction member (125) is configured to be stressed in tension along the longitudinal direction.

7. Core (110) according to claim 6, wherein the extraction member (125) comprises a strip (126) of material mechanically attached at intervals to the slices (111).

8. Core (110) according to claim 6, wherein the extraction member (125) comprises a strip (126) of material having support members (127) arranged at intervals on the strip of material and which are each configured to bear against a slice (111) to drive it in motion along the longitudinal direction when the strip of material is stressed in tension along the longitudinal direction.

9. Core (110) according to any one of claims 1 to 8, further comprising a compacting member (130) configured to hold and / or compress the slices (111) against each other in the molding configuration.

10. Core (110) according to claim 9, further comprising a head heel (112) and a tail heel (113), disposed on either side of the plurality of aligned slices (111), and the compaction member (130) comprising a strip (131) of material mechanically attached to the head heel and passing through the plurality of slices as well as the tail heel, and the tail heel preferably comprising a locking member (132) configured to lock the strip of material in position.

11. Core (110) according to any one of claims 1 to 10, wherein the slices (111) are similar to each other and each comprises a first face and a second face opposite the first face, by which the slices are configured to come into contact with each other, said first face being convex, preferably in the form of a convex spherical portion, and said second face being also convex, preferably in the form of a convex spherical portion, or concave, preferably in the form of a concave spherical portion.

12. Core (110) according to any one of claims 1 to 10, wherein the plurality of slices (111) comprises slices said to be even and slices said to be odd, aligned alternately along the longitudinal direction, and each having a first face and a second face opposite to the first face, by which the slices are configured to come into contact with each other, said first face and second face of the odd slices being convex, preferably in the form of a convex spherical portion, and said first face and second face of the even slices being concave, preferably in the form of a concave spherical portion.

13. Core (110) according to any one of claims 1 to 12, the slices (111) further comprising each at least one pressure transfer opening (123), extending along the longitudinal direction, the pressure transfer openings of the plurality of slices being opposite each other in the molding configuration, and the slices comprising each at least one pressure distribution opening (124), communicating with the at least one pressure transfer opening and extending transversely to the longitudinal direction.

14. Core (110) according to any one of claims 1 to 13, further comprising a tubular vacuum bag (140), in which is arranged the plurality of slices (111).

15. Molding device (100), comprising a mold (105) having at least one cavity (107) configured to receive a hollow composite profile (3), and at least one core (110) conforming to any one of claims 1 to 14, configured to be disposed in the hollow composite profile.

16. A method (200) for molding a hollow composite profile (3) onto a composite part (2) using a molding device (100) according to claim 15, comprising the following steps: - a step (215) of placing a preformed hollow composite profile (3) into a cavity (107) of the mold, the hollow composite profile preferably being a composite stiffener; - a step (220) of positioning a core (110) in the profile hollow composite, the core being in its molding configuration; - a draping step (225) of the assembly comprising the hollow composite profile (3) and the core (110) with the composite part (2), the composite part being preferably a composite skin; - a step (235) of co-cooking the assembly comprising the hollow composite profile, the core with the composite part and the composite part; - a step (230) of extracting the core (110) from the hollow composite profile, in which the core is moved from its molding configuration to its extraction configuration by mechanical stressing of the extraction member in the longitudinal direction; the extraction step (230) being implemented either following the co-firing step (235), or following the draping step (225) and before the co-firing step (235).

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