Soluble core for manufacturing hollow parts made of organic matrix composites

Abstract

A shaped core comprising a liquid-soluble body and a polymeric resin skin coated on the liquid-soluble body. A method for making the shaped core. An assembly of the shaped core and a hollow part (62) made of an organic-based composite. A hollow part (62) made of an organic-based composite comprising a cavity (80) covered with a polymeric resin skin (54). A method for manufacturing the hollow part (62).

Description

Technical Field

[0001] This disclosure relates to the manufacture of hollow components made of organic-based composite materials, particularly for turbomachinery, and especially to organic-based composite (OMC) hollow components. More specifically, this disclosure relates to a molded core for manufacturing OMC components, a method for manufacturing the molded core, a method for manufacturing such OMC hollow components (e.g., hollow OMC components), and the components thus obtained.

[0002] Existing technology

[0003] CMO components are typically used in aero engines, such as aero turbomachinery, to reduce their weight while ensuring the required mechanical properties, especially stiffness.

[0004] These CMO components are typically used to manufacture fan module components, such as fan blades or outlet guide vanes (OGV).

[0005] These CMO components can be produced using fiber reinforcements made by three-dimensional weaving, in which the threads are interwoven in a three-dimensional manner (referred to as “three-dimensional interlocking” weaving), and the fiber reinforcements are impregnated in an organic matrix.

[0006] The organic matrix can be injected in liquid form according to the LCM (Liquid Composite Molding) process, for example according to the VARTM (Vacuum Assisted Resin Transfer Molding) process.

[0007] Methods such as stamping, hot pressing, or additive manufacturing can also be used.

[0008] CMO can withstand temperatures from 100°C to 250°C. This type of material can replace metal parts in certain parts of turbomachinery, and is particularly suitable for fan blades and / or outlet guide vanes.

[0009] Furthermore, the use of such materials helps optimize the performance of turbomachinery or turbomachinery equipment, especially by reducing the overall mass of the turbomachinery, thereby reducing fuel consumption and consequently reducing harmful emissions (CO, CO2, NO). x wait).

[0010] Climate change is a key concern for numerous legislative and regulatory bodies worldwide. In fact, various countries have already implemented, are implementing, or will implement various carbon emission control policies. In particular, a stringent standard applies to both new and existing aircraft, requiring technological solutions to ensure compliance with current regulations. For many years, civil aviation has been actively committed to contributing to addressing climate change.

[0011] Technological research has significantly improved the environmental performance of aircraft. To improve aircraft energy efficiency, various factors affecting the entire design and development phase are now being considered. These factors aim to produce more energy-efficient and environmentally friendly aerospace components and products, whose integration and use in civil aviation have a moderate environmental impact.

[0012] Therefore, reducing negative impacts on the climate is an area that requires continuous improvement. This is achieved by adopting various methods and utilizing sound development and manufacturing practices to minimize greenhouse gas emissions and thus reduce the environmental footprint.

[0013] This ongoing research and development effort focuses on next-generation aero engines, aircraft weight reduction (especially through the use of materials and lighter avionics), the development of electrical technologies to provide propulsion, and aviation biofuels as an important complement to technological advancements.

[0014] To reduce the weight of fan blades and / or outlet guide vanes made of CMO, it is known to manufacture hollow blades.

[0015] Manufacturing methods that allow for the direct production of parts in the desired shape are particularly advantageous from an industrial perspective. In fact, such methods often achieve higher production efficiency. These parts are produced using molds shaped like the desired component.

[0016] However, not all parts are suitable for this type of method. Although forming methods have been extensively developed and can be used with a wide variety of materials, the geometry of the desired part is often still a limiting factor.

[0017] For example, if the final geometry includes a cavity, the part cannot be directly produced by molding.

[0018] However, solutions already exist for manufacturing components with chambers, such as placing a core in a mold and removing or cleaning the core after the component is manufactured.

[0019] FR3125238 discloses a core comprising a material that decomposes upon contact with water or humid air. This material is present at grain boundaries, causing the core to fracture upon contact with water or humid air, thus allowing it to be removed.

[0020] However, removing the core after the part is completed complicates the molding process or requires the use of special tools. In addition, core removal requires creating a large opening between the cavity and the outside of the part, and some part geometries are not suitable for this technique.

[0021] For soluble cores, the core can be dissolved after the desired component is manufactured. Various cores have been proposed, but the achievable component geometry is limited by the core manufacturing process.

[0022] Existing technologies for core manufacturing all have shortcomings, such as limitations in the minimum achievable core size or the complexity of the core manufacturing process. Furthermore, core dissolution methods can be complex and / or involve toxic compounds.

[0023] There is currently a need to improve the methods for manufacturing hollow components using molding processes. Summary of the Invention

[0024] This disclosure aims to overcome at least some of these deficiencies, and in particular to significantly improve aircraft performance, while also helping to reduce the environmental impact of aircraft.

[0025] For this purpose, this disclosure relates to a molded core comprising a soluble body and a polymeric resin skin coated with the soluble body.

[0026] Because the polymeric resin skin coats the entire soluble bulk, the molding core is not exposed to liquids and / or moisture during storage, handling, insertion into the fiber preform, and / or preform molding steps. Similarly, this molding core can be used to form the outer surface of the fiber preform, in which case the molding core is located between the mold surface and the outer surface of the fiber preform.

[0027] Therefore, the molded core will not degrade before it is removed from the part.

[0028] Furthermore, during resin injection into the fiber preform, the molded core exposed to liquid and / or moisture may begin to dissolve within the fiber preform, contaminating the impregnating resin of the fiber preform, which may alter the mechanical properties of the resin and the final part.

[0029] It should be understood that a soluble bulk may contain materials that dissolve upon contact with the liquid, either through complete dissolution by the soluble bulk itself, or through grain boundary dissolution and fragmentation of the soluble bulk. The fragments can be easily removed from the cavities formed by grain boundary dissolution and fragmentation of the soluble bulk.

[0030] It should be understood that the melting temperature of the polymer resin skin is lower than that of the soluble bulk.

[0031] In some embodiments, the polymeric resin skin may be a thermosetting resin.

[0032] In some embodiments, the polymeric resin skin may be a thermoplastic resin.

[0033] In some implementations, the soluble bulk is soluble in a liquid.

[0034] As a non-limiting example, the liquid may be an aqueous solution or water.

[0035] When a water-soluble substrate is selected, the component is allowed to have a removal opening that can remove the soluble substrate. The removal opening is smaller than the opening used in the prior art, especially less than 5 mm, or even less than 4 mm.

[0036] Furthermore, from an environmental and safety perspective, water is less harmful than other liquids, such as non-aqueous solvents, and reduces the risks faced by operators.

[0037] In some embodiments, the soluble bulk may comprise a soluble thermoplastic polymer.

[0038] As a non-limiting example, the soluble thermoplastic polymer is soluble in non-aqueous solvents such as acetone, ethanol, methanol, or isopropanol.

[0039] In some implementations, the soluble bulk may contain a material that decomposes upon contact with a liquid.

[0040] As a non-limiting example, the soluble bulk may decompose upon contact with a liquid such as an aqueous solution or water.

[0041] From an environmental and safety perspective, water is harmless and reduces the risks faced by operators.

[0042] As a non-limiting example, the soluble bulk may include a composite material, which on one hand comprises the formula M n+ 1AlC n The first phase, wherein n = 1 to 3, M is a transition metal selected from titanium, niobium, chromium or zirconium, and the second phase, of the formula Al4C3, is included on the other hand.

[0043] As a non-limiting example, the first phase is one of the following: Ti3AlC2, Ti2AlC, Cr2AlC, Zr2AlC, Zr3AlC2, Nb4AlC3, or Nb2AlC.

[0044] The combination of the first phase and the second phase of formula Al4C3 is particularly advantageous. In fact, aluminum carbide (Al4C3) is an inorganic compound with a very high melting point (2200°C) and is readily hydrolyzed in aquatic environments at room temperature. Therefore, the composite material used for the molded core in this disclosure incorporates this aluminum carbide second phase at the grain boundaries of the first phase. This makes the composite material highly reactive to aquatic environments. The degradation of aluminum carbide, accompanied by volume changes and gas release, can cause grain boundary fragmentation and crack propagation in the initial first phase. This allows the hydrolysis to extend a relatively long distance, thus facilitating the fragmentation and delamination of the molded core. In other words, the composite material forming the molded core can initially be dense and bulky, and can be converted into powder through hydrolysis.

[0045] This disclosure also relates to an assembly of the aforementioned molded core and a hollow component made of an organic-based composite material, wherein the glass transition temperature of the polymeric resin is greater than or equal to the glass transition temperature of the organic matrix of the hollow component made of the organic-based composite material.

[0046] Since the glass transition temperature of the polymeric resin is greater than or equal to the glass transition temperature of the organic matrix, the polymeric resin of the skin will not degrade during the step of polymerizing the impregnating resin to form the organic matrix of the hollow component made of the organic matrix composite.

[0047] In some embodiments, the polymeric resin may be different from the organic matrix.

[0048] In some embodiments, the polymeric resin and the organic matrix may have the same properties; for example, they may be completely identical.

[0049] This disclosure also relates to a method for preparing the molded core as described above, the method comprising the following steps: - Steps for manufacturing a soluble bulk; - The step of coating the soluble matrix with a coating resin; - The step of converting the coating resin to produce a polymeric resin skin coated with a soluble matrix.

[0050] It should be understood that the coating process may be performed in multiple application steps and with appropriate tools to cover all surfaces of the core, including, for example, surfaces in contact with the receiving support or quenching support.

[0051] In some embodiments, the steps of manufacturing the soluble body may include a powder mixing step, a step of at least partially liquefying the powder mixture (e.g., by heating the powder mixture), a step of forming the soluble body by pouring the at least partially liquefied powder mixture into a mold, a step of solidifying in the mold, and a step of demolding the soluble body from the mold.

[0052] The soluble matrix, once solidified, is soluble in liquids such as water.

[0053] As a non-limiting example, the powder mixture may be a mixture of sodium nitrate, potassium nitrate, and zirconium silicate.

[0054] As a non-limiting example, the powder mixture may contain 13.3% by mass of sodium nitrate (NaNO3), 33.3% by mass of zirconium silicate (SiO4Zr), and 53.4% ​​by mass of potassium nitrate (KNO3).

[0055] In some embodiments, the coating step can be carried out by immersing the soluble bulk into a coating resin bath.

[0056] In some implementations, the coating step can be carried out by applying a coating resin to a soluble substrate, for example, using a brush or sprayer.

[0057] In some embodiments, the coating resin may be a thermosetting resin.

[0058] When the coating resin is a thermosetting resin, the conversion step includes the step of polymerizing the coating resin, which is carried out by heat-treating the coating resin to form a polymerized resin skin.

[0059] As a non-limiting example, the coating resin may be an epoxy resin, such as an epoxy resin sold under the brand names PR520 or RTM6.

[0060] In some embodiments, the coating resin may be a thermoplastic resin.

[0061] When the coating resin is a thermoplastic resin, it is heated prior to the coating step to produce a resin with sufficient fluidity to coat the soluble bulk. After the soluble bulk is coated, the forming step includes cooling the coating resin to form a polymeric resin skin.

[0062] It should be understood that the thermoplastic resin is polymerized prior to the coating step.

[0063] As a non-limiting example, the coating resin may be a polyamide resin (polyamide 6 or polyamide 6,6), polycarbonate, polyethylene terephthalate, or a copolymer, such as glycosylated polyethylene terephthalate.

[0064] This disclosure also relates to a method for manufacturing a hollow component made of an organic-based composite material, the method comprising the following steps: - The steps for preparing the molded core as described above; - The step of assembling the molded core as described above with the fiber preform that forms the hollow component precursor made of ceramic matrix composite material; - The step of laying the fiber preform and molding core into the mold; - The steps for closing the mold; - The step of impregnating the fiber preform with impregnation resin; - The step of polymerizing impregnating resin in a mold to form an organic matrix; - The step of demolding the hollow component made of organic-based composite material and the molding core from the mold; and - Steps to remove soluble components; The glass transition temperature of the coating resin is greater than or equal to the glass transition temperature of the impregnating resin.

[0065] As a non-limiting example, the fiber preform may comprise glass fiber, carbon fiber, aramid fiber, and / or a mixture of the above fibers.

[0066] As a non-limiting example, the fiber preform may also include metal inserts, such as leading edge guards and / or threaded inserts.

[0067] Since the glass transition temperature of the coating resin is greater than or equal to that of the impregnation resin, the coating resin will not degrade during the step of polymerizing the impregnation resin to form the organic matrix of the hollow component made of the organic matrix composite material after it has polymerized to form the polymerized resin skin.

[0068] In some implementations, the coating resin may be different from the impregnation resin.

[0069] In some embodiments, the coating resin and the impregnation resin may have the same properties; for example, they may be identical.

[0070] In some implementations, the fiber preform can be formed between the assembly step and the laying step.

[0071] The forming process improves the positioning of fibers in the fiber preform and limits the forces and displacements during mold closing, especially during the lay-up and mold closing steps.

[0072] In some embodiments, the wet fiber preform can be shaped and dried before the lay-up step.

[0073] As a non-limiting example, drying is carried out at a temperature greater than or equal to 100°C and less than or equal to 130°C, for example at 120°C.

[0074] It should be understood that the polymer resin skin of the molding core protects the soluble matrix from any damage, thus enabling the molding of wet fiber preforms.

[0075] In some implementations, the molding core may be flush with the outer surface of the fiber preform during the assembly step.

[0076] When the hollow component made of organic-based composite material is demolded from the mold, the molding core is accessible at its flush outer surface. The polymeric resin skin coated with a soluble matrix can be torn off, and the soluble matrix can be dissolved.

[0077] In some embodiments, the soluble bulk removal step may include drilling a channel for removing the soluble bulk from a hollow component made of an organic-based composite material to access the soluble bulk.

[0078] In some embodiments, the molding core may include a channel core configured to form channels for removing soluble bulk from a hollow component made of an organic-based composite material.

[0079] It should be understood that once the soluble bulk portion of the channel core dissolves, channels for removing the soluble bulk are formed in hollow components made of organic-based composite materials.

[0080] The channels for removing soluble bulk allow for the dissolution or breakdown of the soluble bulk by spraying liquid onto it.

[0081] As a non-limiting example, the diameter of the channel may be greater than or equal to 5 mm and less than or equal to the maximum thickness of the soluble bulk to be removed.

[0082] In some implementations, the step of removing the soluble matrix may include dissolving or breaking down the soluble matrix by means of a pressurized liquid (e.g., water) jet.

[0083] Liquid pressure represents a trade-off between core removal time and the risk of damage to composite components. In fact, higher liquid pressure results in faster core removal.

[0084] In some embodiments, water can be heated to a temperature greater than or equal to 40°C and less than or equal to 95°C, which can accelerate the dissolution of the soluble bulk.

[0085] This disclosure also relates to a hollow component made of an organic-based composite material, comprising a chamber covered with a polymeric resin skin.

[0086] As a non-limiting example, the hollow component made of organic-based composite material could be a fan guide vane, propeller, or fan (FAN) blade known as an OGV (i.e., “Outlet Guide Vane”).

[0087] Brief description of the attached figures

[0088] Other features and advantages of this disclosure will become apparent from the following description of embodiments given by way of non-limiting examples, in conjunction with the accompanying drawings.

[0089] [ Figure 1 ] Figure 1 This is a schematic diagram of the longitudinal section of a turbomachinery.

[0090] [ Figure 2 ] Figure 2 This is a schematic diagram of the steps of coating a soluble body with a coating resin according to one embodiment.

[0091] [ Figure 3 ] Figure 3This is a schematic diagram of the step of coating a soluble body with a coating resin according to the second embodiment.

[0092] [ Figure 4 ] Figure 4 This is a schematic diagram of the step of coating a soluble body with a coating resin according to the third embodiment.

[0093] [ Figure 5 ] Figure 5 This is a flowchart illustrating the steps of a core preparation method according to one embodiment.

[0094] [ Figure 6 ] Figure 6 This is a flowchart illustrating the steps of a method for manufacturing a hollow component made of an organic-based composite material according to one embodiment.

[0095] [ Figure 7 ] Figure 7 This is a schematic diagram of the assembly steps of the core and fiber preform according to one embodiment.

[0096] [ Figure 8 ] Figure 8 This is a schematic diagram of the forming steps of a fiber preform according to one embodiment.

[0097] [ Figure 9 ] Figure 9 This is a schematic diagram illustrating the shaping of a fiber preform within a mold using a soluble core, according to one embodiment.

[0098] [ Figure 10 ] Figure 10 This is a schematic diagram of the fiber preform impregnation step according to one embodiment.

[0099] [ Figure 11 ] Figure 11 This is a schematic diagram of a hollow component and a soluble core made of an organic-based composite material after demolding, according to one embodiment.

[0100] [ Figure 12 ] Figure 12 This is a schematic diagram of a soluble bulk removal step according to one embodiment.

[0101] [ Figure 13 ] Figure 13 This is a schematic diagram of a hollow component made of an organic-based composite material according to one embodiment.

[0102] [ Figure 14 ] Figure 14 This is a schematic diagram of a hollow component and a soluble core made of an organic-based composite material after demolding from a mold, according to the second embodiment.

[0103] [ Figure 15 ] Figure 15 This is a schematic diagram of a hollow component and a soluble core made of an organic-based composite material after demolding from a mold, according to the third embodiment. Detailed Implementation

[0104] Figure 1 A cross-sectional view of a turbofan engine 10 along a vertical plane passing through its main axis A is shown. The turbofan engine is an example of a turbomachinery. The turbofan engine 10 includes a fan 12, a low-pressure compressor 14, a high-pressure compressor 16, a combustion chamber 18, a high-pressure turbine 20, and a low-pressure turbine 22 along the airflow F from upstream to downstream.

[0105] The terms “upstream” and “downstream” are defined relative to the direction of airflow in the turbomachinery, in this case, according to the direction of airflow F in the turbojet engine 10.

[0106] The turbojet engine 10 includes a fan housing 24 that extends rearward and downstream and connects to an intermediate housing 26; the intermediate housing 26 includes an outer casing 28 and an inner casing 30 disposed inside and parallel to the outer casing 28 in a radial direction R. The radial direction R is perpendicular to the main shaft A.

[0107] The terms “external” and “internal” are defined relative to the radial direction R, such that the internal portion of the element is closer to the spindle A in the radial direction than the external portion of the element.

[0108] The intermediate housing 26 also includes circumferentially distributed structural arms 32 that extend radially from the inner housing 30 to the outer housing 28. For example, the structural arms 32 are bolted to the outer housing 28 and the inner housing 30. The structural arms 32 provide structural rigidity to the intermediate housing 26.

[0109] Main shaft A is the axis of rotation of turbojet engine 10 and low-pressure turbine 22. Therefore, main shaft A is parallel to the axial direction.

[0110] The low-pressure turbine 22 includes a plurality of impellers that form the rotor of the low-pressure turbine 22.

[0111] In the following text, elements common to different embodiments are labeled with the same numerical reference numerals.

[0112] Figure 2 A molded core 50 according to one embodiment is shown. The molded core 50 includes a soluble body 52 coated with a polymeric resin skin 54.

[0113] In the following text, elements common to different embodiments are labeled with the same numerical reference numerals.

[0114] The method 100 for preparing the molded core 50 includes a first step 102 of manufacturing a soluble body 52.

[0115] As a non-limiting example, the soluble body 52 is soluble in a liquid; the soluble body 52 may include materials that decompose upon contact with the liquid. The liquid may be an aqueous liquid, such as water; or a non-aqueous solvent.

[0116] Preparation method 100 then includes step 104 of coating the soluble body 52 with coating resin 56.

[0117] like Figure 2 As shown, the coating step 104 can be carried out by immersing the soluble body 52 in a bath of coating resin 56.

[0118] like Figure 3 As shown, the coating step 104 can be carried out by applying the coating resin 56 to the soluble body 52 with a brush.

[0119] like Figure 4 As shown, the coating step 104 can be carried out by spraying the coating resin 56 onto the soluble body 52.

[0120] like Figure 2 As shown, when the soluble body 52 is coated with coating resin 56, the preparation method 100 includes step 106 of converting coating resin 56 to obtain polymeric resin skin 54.

[0121] As a non-limiting example, when the coating resin 56 is a thermosetting resin, the conversion step 106 may include the step of polymerizing the coating resin 56.

[0122] As a non-limiting example, when the coating resin 56 is a thermoplastic resin, the conversion step 106 may include a step of cooling the coating resin 56.

[0123] As a non-limiting example, the coating resin can be a thermosetting resin, such as an epoxy resin, for example, an epoxy resin sold under the brand name PR520N®.

[0124] The manufacturing method 200 of the hollow component 62 made of organic-based composite material will be based on Figures 6 to 13 Please provide an explanation.

[0125] like Figure 6 and Figure 7 As shown, manufacturing method 200 includes a first step 100 of producing a molded core 50, followed by a step 202 of assembling the molded core 50 with a fiber preform 60. The fiber preform 60 forms a precursor to a hollow component 62 made of an organic-based composite material.

[0126] like Figure 6 and Figure 8 As shown, manufacturing method 200 may next include step 204 of forming the fiber preform 60. Forming step 204 is optional.

[0127] If the fiber preform 60 is wet during the forming step 204, the forming step 204 may include a step of drying the fiber preform 60.

[0128] Manufacturing method 200 then includes step 206 of laying the fiber preform 60 and the molding core 50 into the mold 70.

[0129] like Figure 6 As shown, manufacturing method 200 next includes step 208 of closing the mold 70. Figure 9 In the image, mold 70 is shown as closed, meaning that closing step 208 has been completed. Mold 70 may include an inlet opening and an outlet opening for impregnating resin.

[0130] like Figure 6 As shown, manufacturing method 200 next includes step 210 of impregnating the fiber preform 60 with impregnation resin 58. In Figure 10 In the middle, the fiber preform 60 has been completely impregnated with impregnation resin 58.

[0131] The glass transition temperature of the coating resin 56 is greater than or equal to the glass transition temperature of the impregnating resin 58.

[0132] As a non-limiting example, the impregnating resin 58 and the coating resin 56 may be thermosetting resins, such as epoxy resins, for example, epoxy resins sold under the brand name PR520N®.

[0133] like Figure 6 As shown, the manufacturing method 200 then includes the following step 212: polymerizing the impregnation resin 58 in the mold 70 to form an organic matrix 64 of the hollow component 62 made of an organic matrix composite material.

[0134] The glass transition temperature of the polymer resin skin 54 is greater than or equal to the glass transition temperature of the organic matrix 64.

[0135] In fact, after the conversion step 106 of the method 100 for preparing the molded core 50, the resin 56 is coated to form a polymeric resin skin 54, and after the polymerization step 212 of the method 200 for manufacturing the hollow part 62 made of organic matrix composite material, the resin 58 is impregnated to form an organic matrix 64.

[0136] like Figure 6 As shown, the manufacturing method 200 then includes step 214: demolding the hollow part 62 made of organic-based composite material from the mold, with the molding core 50 present in the hollow part 62 made of organic-based composite material.

[0137] Figure 11 This is a schematic diagram of the hollow component 62 made of organic-based composite material and the soluble core 50 after demolding from the mold in step 214.

[0138] like Figure 6 As shown, manufacturing method 200 then includes step 216 of removing soluble bulk 52.

[0139] Figure 12 A schematic diagram of step 216 for removing soluble bulk 52, including drilling a removal channel 68 using drill bit 72 (e.g. Figure 13 The steps are shown below.

[0140] The removal channel 68 allows access from the outside of the hollow component 62, made of organic-based composite material, to the soluble body 52.

[0141] As a non-limiting example, removal step 216 includes the step of injecting hot water, for example, hot water at 40°C to 95°C, preferably under pressure, to dissolve or decompose / break up the soluble bulk 52 and remove it through removal channel 68.

[0142] Figure 13 A schematic diagram of a hollow component 62 made of an organic-based composite material, obtained after the removal step of the soluble bulk 52. The hollow component 62 made of the organic-based composite material includes a chamber 80 covered with a polymeric resin skin 54.

[0143] Figure 14 This is a schematic diagram of the hollow component 62 and the soluble core 50 made of organic-based composite material after demolding from the mold in step 214, according to the second embodiment.

[0144] exist Figure 14 In the illustrated embodiment, the molding core 50 includes a channel core 74 configured to form a removal channel 68. The channel core 74 is flush with the outer surface 66 of the hollow component 62 made of an organic-based composite material.

[0145] Figure 15 This is a schematic diagram of the hollow component 62 and the soluble core 50 made of organic-based composite material after demolding from the mold in step 214, according to the third embodiment.

[0146] exist Figure 15 In the embodiment shown, the molding core 50 is flush with the outer surface 66 of the hollow component 62 made of organic-based composite material.

[0147] exist Figure 14 and Figure 15In one embodiment, the soluble bulk removal step 216 includes the following steps: tearing open the polymeric resin skin 54, which is flush with the outer surface 66 of the hollow component 62 made of organic-based composite material, so as to have a pathway from the outside of the hollow component 62 made of organic-based composite material to the soluble bulk 52.

[0148] Step 216, which removes the soluble matrix 52, is similar to the removal step 216 described above.

[0149] Although this specification has been written with reference to specific embodiments, it will be apparent that various modifications and variations can be made to these examples without departing from the overall scope of the invention as defined by the claims. Furthermore, features of the different embodiments mentioned can be combined to form other embodiments. Therefore, the specification and drawings should be considered illustrative rather than restrictive.

[0150] Although the invention has been described with reference to specific embodiments, it will be apparent that modifications and variations can be made to these examples without departing from the full scope of the invention as defined by the claims. Specifically, features of the different embodiments shown / mentioned can be combined to form other embodiments. Therefore, the specification and drawings should be understood as illustrative rather than restrictive.

[0151] It is equally evident that all features described by the reference method can be applied individually or in combination to the apparatus, and conversely, all features described by the reference apparatus can be applied individually or in combination to the method.

Claims

1. A molded core (50) comprising a soluble body (52) soluble in an aqueous solution or water, and a polymeric resin skin (54) coating the soluble body (52), wherein the polymeric resin skin (54) coating layer on the soluble body (52) is obtained by immersing the soluble body (52) in a bath of coating resin (56), or by applying the coating resin (56) to the soluble body (52) using a brush or sprayer.

2. The molding core (50) according to claim 1, characterized in that, Soluble bulk (52) includes materials that decompose when in contact with aqueous solutions or water.

3. An assembly comprising a molded core (50) according to claim 1 or 2 and a hollow component (62) made of an organic-based composite material, wherein the glass transition temperature of the polymeric resin is greater than or equal to the glass transition temperature of the organic matrix (64) of the hollow component (62) made of the organic-based composite material.

4. A method (100) for preparing the molded core (50) according to claim 1 or 2, comprising the following steps: - Step (102) of manufacturing the soluble bulk (52); - Step (104) of coating the soluble body (52) with coating resin (56) by immersing the soluble body (52) in a bath of coating resin (56) or by applying coating resin (56) to the soluble body (52) using a brush or sprayer. - Step (106) of converting coating resin (56) to obtain a polymeric resin skin (54) coated with soluble body (52).

5. A method (200) for manufacturing a hollow component (62) made of an organic-based composite material, comprising the following steps: - Step (100) of preparing the molded core (50) according to claim 4; - The step (202) of assembling the molding core (50) according to claim 1 or 2 with the fiber preform (60) that forms the precursor of the hollow component made of the organic matrix composite material; - Step (206) of laying the fiber preform (60) and the molding core (50) into the mold (70); - Step (208) of closing the mold (70); - Step (210) of impregnating the fiber preform (60) with impregnation resin (58); - Step (212) to polymerize the impregnating resin (58) in the mold (70) to form an organic matrix (64); - The step (214) of demolding the hollow component (62) and molding core (50) made of the organic-based composite material from the mold; and - Step (216) to remove soluble matrix (52); The glass transition temperature of the coating resin (56) is greater than or equal to the glass transition temperature of the impregnation resin (58).

6. The manufacturing method (200) according to claim 5, characterized in that, The removal step (216) of the soluble body (52) includes a drilling step: drilling a channel (68) for removing the soluble body (52) from the hollow part (62) made of organic-based composite material to reach the soluble body (52).

7. The manufacturing method (200) according to claim 5, wherein the molding core (50) includes a channel core (74) for forming a channel (68) for removing soluble bulk from a hollow component (62) made of an organic-based composite material.

8. The manufacturing method (200) according to any one of claims 5 to 7, characterized in that, The step (216) of removing the soluble body (52) includes: dissolving the soluble body (52) or breaking the soluble body (52) by pressurized liquid jet.

9. A hollow component (62) made of an organic-based composite material, comprising a cavity (80) covered with a polymeric resin skin (54).

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