Method for manufacturing a cellular structure for a part, in particular of an aircraft turbine engine

Abstract

The invention relates to a method for manufacturing a cellular structure for a part, in particular of an aircraft turbine engine, this cellular structure comprising an array of cells (86), a first skin (82) made of composite material covering the array (86), and optionally a second skin (84) made of composite material having the array (86) between the first and second skins, the method being characterized in that it comprises the steps consisting in: (a) producing a first stack (820) of layers of fibres by lay-up so as to form the first skin, (b) depositing at least one first interface film (800) by lay-up on the first skin, (c) positioning the array of cells (86) on the first interface film, (d) optionally depositing at least one second interface film (802) by lay-up on the array (86), and (e) optionally producing a second stack (840) of layers of fibres by lay-up so as to form the second skin.

Description

[0001]DESCRIPTION TITLE: METHOD FOR MANUFACTURING A HONEYCOMB STRUCTURE FOR A PARTICULAR COMPONENT OF AN AIRCRAFT TURBOMACHINE Technical Field The invention relates to the field of honeycomb structures for a part, in particular for an aircraft turbomachine. More specifically, the present invention relates to a method for manufacturing a honeycomb structure for a part, in particular for an aircraft turbomachine. Technical Background The prior art includes, in particular, documents CN-A-112743874, US-B2-7186310, FR-A3-3106777, EP-B1-3444107 and FR-3131707. A honeycomb structure, also known as a honeycomb structure (H&H), comprises one or more skins covering a network of cells. This network of alveoli comprises alveolar cells that are joined together and arranged according to a predetermined pattern. This arrangement gives the structure high mechanical properties.In particular, it requires high mechanical strength while remaining lightweight. The honeycomb structure can be made of metallic and / or composite materials. Honeycomb structures, especially for aircraft turbomachinery components, are typically manufactured by producing the honeycomb grid and skins separately, then assembling them to form the whole (for example, by welding, bonding, and using other assembly and reinforcement tools). However, this method of manufacturing the honeycomb structure can be complex because it requires a large number of operations and tooling, many of which are not highly automated. In this context, it is worthwhile to propose a solution that addresses at least one of the aforementioned drawbacks, particularly by optimizing and simplifying the manufacturing of a honeycomb structure for a component.in particular of an aircraft turbomachine. Summary of the invention The present invention offers a simple, efficient, and economical solution to the aforementioned drawbacks of the prior art. To this end, the invention relates to a method for manufacturing a honeycomb structure for a part, in particular of an aircraft turbomachine, this honeycomb structure comprising a network of cells, a first skin of composite material covering the network of cells, and optionally a second skin of composite material with the network of cells positioned between said first and second skins. According to the invention, the method comprises the steps of: (a) creating a first stack of several layers of fibers by draping so as to form the first skin, (b) depositing at least one first interface film by draping onto the first skin, (c) positioning the network of cells on the first interface film,(d) optionally deposit at least one second interface film by draping over the honeycomb network, and (e) optionally perform a second stacking of several fiber layers by draping to form the second skin. Thus, this solution makes it possible to achieve the aforementioned objective. In general, the process according to the invention simplifies the production of a honeycomb structure by using the draping technique to deposit both fiber layers and at least one interface film. Draping can also be compatible when using a thermoplastic matrix to produce the honeycomb structure. Furthermore, draping can be performed manually or automatically (for example, by a suitable machine). For example, draping can be performed using the AFP (Automated Fiber Placement) technique.The invention uses the ATL (Automated Tape Laying) or P&P (Pick & Place) techniques. The invention therefore offers the advantage of a simple design, high reliability, and minimal impact in terms of cost, weight, and size. Furthermore, the invention reduces environmental impact by improving and simplifying the manufacturing of components (i.e., a honeycomb structure) for an aircraft turbomachine. "Draping" refers to the successive layering and stacking of multiple plies of composite material (such as fiber layers and the interface film(s)) to form, in this application, the skin(s) of the honeycomb structure. The plies can be draped at different orientations (such as 0°, 45°, etc.).-45° (or 135°); 90°). The manufacturing process according to the invention may include one or more of the following features, taken individually or in combination with each other: - that at least one of the steps (a), (b), (c), (d) and (e) includes a substep of compacting (ai, bi, ci, di, ei) the fiber layers of the first and / or second stacks and of the first and / or second interface films, such as with a compacting roller which is, for example, integrated into a draping device for the substeps (ai, bi, di, ei), or with a pressure device for the substep (ci); - the steps (a) and (e) each include a substep of cooking (aii, eii) the first and second stacks to form the first and second skins respectively; - at least one of the sub-stages (aii, eii) of cooking is carried out during the draping of the first and / or second stacks with a heating device integrated into the draping device,in which the first and / or second stacks are heated, for example, by a laser source, a plasma torch, an ultraviolet lamp, or a flash lamp; - at least one of the curing substeps (aii, eii) is carried out after draping the first and / or second stacks with an external heating device, in which the first and / or second stacks are heated, for example, in a heating device; - at least one of steps (a) and (e) is carried out by draping at least one of the fiber layers of the first and / or second stacks in a direction different from that of the other fiber layers of the corresponding stack; - before step (c), the first skin and the first interface film obtained in step (b) are cooled with a cooling device, for example, of the induction type.of the forced-air type or with a heat transfer fluid; - the first skin and the first interface film are cooled to a temperature of approximately 20°C (for example, with a tolerance of approximately + / -1°C); - at least one of the first and second skins comprises perforations, wherein the process further comprises a perforation step (f) of one of the first and second skins which is carried out after step (e); - the fiber layers of at least one of the first and second stacks comprise fibers pre-impregnated with a first thermoplastic material; - the cell array is made of metal, such as aluminum, thermoplastic, paper, or cardboard,in which the paper or cardboard is, for example, impregnated with a phenolic or aramid resin; - at least one of the first and second interface films comprises a second thermoplastic material; - the second thermoplastic material has a softening temperature lower than that of the first thermoplastic material; - the first interface film has a thickness of less than 0.5 mm, preferably between 0.05 and 0.5 mm; - the second interface film has a thickness of less than 0.5 mm, preferably between 0.05 and 0.5 mm; -- at least one of steps (a) to (e) is carried out manually or automatically; -- the first thermoplastic material is chosen from the polyetherketone (PEK) or polyaryletherketone (PAEK) family, such as low melting point polyaryletherketone (LM-PAEK), polyetheretherketone (PEEK), polyetheretherketoneketone (PEEKK), polyetherketoneketone (PEKK),polyetherketone (PEKEKK), etc.; polyphenylene sulfide (PPS); and an amorphous thermoplastic (such as polyetherimide (PEI), polyethersulfone (PESU), polyimide (TPI), polyamide-imide (PAI), polysulfone (PSU), etc.); -- the second material is chosen from the polyetherketone (PEK) or polyaryletherketone (PAEK) family, such as low-melting-point polyaryletherketone (LM-PAEK), polyetheretherketone (PEEK), polyetheretherketoneketone (PEEKK), polyetherketoneketone (PEKK), polyetherketoneetherketone (PEKEKK), etc.; polyphenylene sulfide (PPS); and an amorphous thermoplastic (such as polyetherimide (PEI), polyethersulfone (PESU), polyimide (TPI), polyamide-imide (PAI), polysulfone (PSU), etc.); -- the second thermoplastic material is free of additional filler(s),such as fibers or components in particle form; -- the first interface film and / or the second interface film is (or are) an adhesive film; -- the honeycomb structure is made of metal (such as aluminum), thermoplastic, paper (for example impregnated with a phenolic or aramid resin) or cardboard (for example impregnated with a phenolic or aramid resin); -- the honeycomb structure is made of amorphous thermoplastic (such as polyetherimide (PEI)) or semi-crystalline thermoplastic (such as polyaryletherketone (PAEK)); -- the honeycomb structure comprises polygonal cells, for example triangular, quadrangular, pentagonal or hexagonal and / or rounded; -- the part, in particular of the aircraft turbomachine, is an annular housing, an acoustic panel or a self-stiffening panel. The invention also relates to a honeycomb structure for a part, in particular for an aircraft turbomachine,This honeycomb structure is produced by a manufacturing process exhibiting any one of the characteristics described below. The honeycomb structure may therefore comprise the honeycomb grid, the first skin of material covering the honeycomb grid, and optionally the second skin of composite material with the honeycomb grid positioned between said first and second skins. The honeycomb structure may further comprise at least the first interface film located between the honeycomb grid and the first skin of composite material. Optionally, the honeycomb structure may also include at least the second interface film located between the honeycomb grid and the second skin of composite material. The invention may further relate to a component, in particular of an aircraft turbomachine (or an aircraft nacelle), comprising at least one honeycomb structure as described above. This component may be an annular housing,an acoustic panel or a self-stiffening panel. The invention may also relate to an aircraft turbomachine comprising at least one part as described above. The invention may also relate to an aircraft nacelle comprising at least one part as described above. This nacelle may extend around the turbomachine. Brief description of the figures The present invention will be better understood and other details, features, and advantages of the present invention will become clearer upon reading the description of a non-limiting example that follows, with reference to the accompanying drawings in which: Figure 1 is a schematic perspective view of an aircraft turbomachine; Figure 2 is a schematic perspective and axial sectional view of a first example of a honeycomb structure according to the invention for, for example, a part of the turbomachine of Figure 1.Figure 3 is a schematic perspective and partial view of a second example of a honeycomb structure according to the invention for a part, for example, of the turbomachine of Figure 1; Figure 4 is a schematic partial axial cross-sectional view of the honeycomb structure of Figure 2; Figure 5 is a block diagram representing manufacturing steps of the honeycomb structure of Figure 3 or 4; Figure 6 is a schematic axial cross-sectional view of an installation according to the invention for producing the honeycomb structure of Figure 3 or 4, or the manufacturing steps of Figure 5; Figure 7 is a schematic axial cross-sectional view representing a draping step of several layers of fibers to form a first skin of the honeycomb structure of Figure 3 or 4; Figure 8 is a schematic axial cross-sectional view representing a step of depositing a first interface film onto the first skin obtained in Figure 7.Figure 9 is a schematic axial cross-sectional view representing a step of positioning a honeycomb network on the first interface film obtained in Figure 8. Figure 10 is a schematic axial cross-sectional view representing a step of depositing a second interface film onto the honeycomb network obtained in Figure 9. Figure 11 is a schematic axial cross-sectional view representing a step of draping several layers of fibers onto the second interface film obtained in Figure 10 to form a second skin of the honeycomb structure. Figure 12 is a schematic axial cross-sectional view representing a step of perforating the first skin of the honeycomb structure obtained in Figure 11. Elements having the same functions in the different embodiments have the same reference numerals in the figures. Detailed description of the invention. By convention, in the following description,The terms "longitudinal" and "axial" describe the orientation of structural elements extending along a longitudinal axis (such as that of a turbomachine). The terms "radial" or "vertical" describe the orientation of structural elements extending in a direction perpendicular to the longitudinal axis. The terms "interior" and "exterior," and "internal" and "external," are used with reference to positioning relative to the longitudinal axis. Thus, a structural element extending along the longitudinal axis has an interior face facing the longitudinal axis and an exterior surface opposite its interior surface. Similarly, the terms "upstream" and "downstream" are defined with respect to the direction of gas flow in the turbomachine. The invention applies generally, and not limited to, various types of parts 8,in particular for an aircraft turbomachine 10. The turbomachine 10 can be a turboprop or a turbojet. Figure 1 illustrates an example of a turbomachine 10 extending around a longitudinal axis X. The turbomachine 10 can conventionally comprise, from upstream to downstream, a fan 1, one or more compressors (such as a low-pressure compressor 2 and a high-pressure compressor 3), a combustion chamber 4, one or more turbines (such as a low-pressure turbine 5 and a high-pressure turbine 6), and possibly an exhaust nozzle. The turbomachine 10 can comprise several annular casings, such as a fan casing 7a extending around the fan 1,and an intermediate casing 7b extending around the low-pressure compressor 2 in the example of Figure 1. The invention finds advantageous but not exclusive application in one or more parts 8 from an aircraft turbomachine 10 (such as a turbojet or turboprop type aircraft turbomachine) or an aircraft nacelle (such as a thrust reverser element or module). This nacelle (not shown in the figures) may extend around the turbomachine 10. For example, and without limitation, the part(s) 8 may be an annular casing (such as the fan casing 7a and / or the intermediate casing 7b of Figure 1), an acoustic panel, or a self-stiffening panel. The part 8 may include at least one honeycomb structure 80. The part 8 of the invention may thus be any part, for example, of a turbomachine 10 and / or nacelle,comprising the alveolar structure 80. The alveolar structure 80 comprises a network of alveoli 86 and a first skin 82 made of composite material. The first skin 82 covers the network of alveoli 86. This first skin 82 may advantageously include perforations 822, to form a perforated skin, known as an acoustic skin. Alternatively, the first skin 82 may be a solid skin (or in other words, without perforations). Figure 2 illustrates, in a non-limiting manner, a first configuration of the alveolar structure 80 comprising only the first skin 82 covering the network of alveoli 86. In this first configuration, the alveolar structure 80 is said to be semi-open since alveolar cells composing the network of alveoli 86 may be at least partially open to the outside of this alveolar structure. For example,The first skin 82 (in particular perforated) may be located at a flow duct of an airflow from the turbomachine, and the honeycomb structure 86 may be located on an internal or external surface of the part 8, particularly when this part 8 is an annular casing or an acoustic panel of the turbomachine. This internal or external surface of the part 8 may be located opposite the first skin 82 and may thus form a solid skin covering the honeycomb structure 86. The honeycomb structure 80 may comprise at least two skins 82, 84 made of composite material, respectively, the first skin 82 and a second skin 84; in which the honeycomb structure 86 is located between these two skins 82, 84. The second skin 82 may be optional, particularly when the honeycomb structure 80 is semi-open.as described above. One of the first 82 and second 84 skins may advantageously include perforations 822 to form an acoustic skin, and the other of the first 82 and second 84 skins may form a solid skin (or, in other words, without perforations). Alternatively, the first 82 and second 84 skins may be solid. Figures 3 and 4 illustrate, without limitation, a second configuration of the honeycomb structure 80 comprising the first 82 and second 84 skins, and the network of cells 86 located between these first 82 and second 84 skins. This second configuration is called a sandwich configuration and forms a closed honeycomb structure. For example, the first skin 82 (in particular perforated) can be located at the level of a flow vein of an air flow of the turbomachine and the second skin 84 (whether perforated or solid) can be located at the level of an internal or external surface of the part 8,particularly when this part 8 is an annular housing or an acoustic panel of the turbomachine. Advantageously, the honeycomb structure 80 can include at least one interface film 800, 802. This interface film 800, 802 allows one or more skins 82, 84 to be connected to the honeycomb network 86. In the example in Figure 2, the honeycomb structure 80 can include a first interface film 800 connecting the first skin 82 to the honeycomb network 86. In the examples in Figures 3 and 4, the honeycomb structure 80 can include the first interface film 800 and a second interface film 802. These first 800 and second 802 interface films connect, respectively, the first 82 and second 84 skins to the honeycomb network 86. As illustrated in Figure 4, the first interface film 800 is intercalated between the first skin 82 and the alveolar network 86,and the second interface film 802 is intercalated between the second skin 84 and the honeycomb structure 86. The first interface film 800 and / or the second interface film 802 may be an adhesive film. In an alternative not shown in the figures, the honeycomb structure 80 may comprise several honeycomb structures 86 superimposed one on top of the other, and optionally separated from each other by one or more intermediate skins (commonly called "septa"). The intermediate skin(s) may be made of composite material, in particular in a manner similar to the first and second skins 82.84. The first skin 82 can be formed from a first stack 820 of several layers of fibers (hereafter referred to as first fiber layers). Each of the first fiber layers can comprise unidirectional fibers that may be oriented in directions (or orientations) different from the fibers of the other first fiber layers of this first stack 820. The first skin can have a first thickness E82 that can be less than or equal to 10 mm. This first thickness E82 can be between 0,5 and 5 mm. The second skin 84 may be formed from a second stack 840 of several fiber layers (hereafter referred to as second fiber layers). Each of the second fiber layers may comprise unidirectional fibers that may be oriented in different directions from the fibers of the other second fiber layers in this second stack 840. The second skin 84 may have a second thickness E84 that may be less than or equal to 10 mm. This second thickness E84 may be between 0.5 and 5 mm. The second thickness E84 of the second skin 84 may be different from or the same as the first thickness E82 of the first skin 82. The first stack 820 and / or the second stack 840 may comprise fibers pre-impregnated with a first thermoplastic material. The first 820 stack and / or the second 840 stack may (or can) include carbon fibers, glass fibers,ceramic fibers (such as silicon carbide, glass, or aramid), polyamide fibers, metallic fibers, oxide fibers, or a mixture of at least two of these fibers. The first thermoplastic material may be chosen from the following materials: - the polyetherketone (PEK) or polyaryletherketone (PAEK) family, such as low-melting-point polyaryletherketone (LM-PAEK), polyetheretherketone (PEEK), polyetheretherketoneketone (PEEKK), polyetherketoneketone (PEKK), polyetherketoneetherketoneketone (PEKEKK), etc., - polyphenylene sulfide (PPS), and - an amorphous thermoplastic (such as polyetherimide (PEI), polyethersulfone (PESU), polyimide (TPI), polyamide-imide (PAI), polysulfide (PSU),etc.). Only the first skin 82 may include perforations 822. These perforations 822 may open into the alveolar network 86 (particularly at the alveolar cells described below). Figure 12 illustrates, in a non-limiting manner, perforations 822 formed on the first skin 82. Alternatively, perforations may be formed only on the second skin 84, thus forming an acoustic skin, while the first skin 82 forms the solid skin. The first interface film 800 and / or the second interface film 802 may include a second thermoplastic material. The second thermoplastic material can be chosen from the following materials: - the polyetherketone (PEK) or polyaryletherketone (PAEK) family, such as polyetherketone (PEK), polyetheretherketone (PEEK), polyetheretherketoneketone (PEEKK), polyetherketoneketone (PEKK), polyetherketoneetherketoneketone (PEKEKK), etc., - polyphenylene sulfide (PPS),and - an amorphous thermoplastic (such as polyetherimide (PEI), polyethersulfone (PESU), polyimide (TPI), polyamide-imide (PAI), polysulfone (PSU), etc.). The second thermoplastic material of at least one of the first and second interface films 800, 802 may have a different softening temperature than the first thermoplastic material of at least one of the first and second stacks 820, 840. In particular, the softening temperature of the second thermoplastic material may be lower than that of the first thermoplastic material. This makes it easier and faster to heat the interface film(s) at relatively low temperatures and with less heating energy to create a strong bond between the skin(s) 82, 84 and the cell network 86. The term "softening temperature" refers to...The melting point, particularly in the case of semi-crystalline thermoplastics, or the glass transition temperature, particularly in the case of amorphous thermoplastics. Preferably, the softening point of the second thermoplastic material may be lower than that of the first thermoplastic material. For example, the softening point of the second thermoplastic material may be lower than 350°C. This softening point of the second material may be between 170 and 350°C, preferably around 210°C. The softening point of the first thermoplastic material may be lower than 350°C. This softening point of the first material may be between 170 and 350°C, preferably around 307°C. The softening point may depend on the nature (such as semi-crystalline or amorphous) of the first and second thermoplastic materials. For example,The softening temperature of the first thermoplastic material and / or the second semi-crystalline thermoplastic material (e.g., LM-PAEK, PEEK, or PEKK) can be between 300 and 350°C. Alternatively, the softening temperature of the first thermoplastic material and / or the second amorphous thermoplastic material (e.g., PEI and PSU) can be between 170 and 250°C. Advantageously, the second thermoplastic material (of the first interface film 800 and / or the second interface film 802) can be free of additional filler(s), such as fibers or components in particulate form. The first interface film 800 can have a third layer E800 that is less than 0.5 mm thick. Preferably, this third layer E800 can be between 0.05 and 0.5 mm thick. The second 802 interface film may have a fourth E802 thickness that is less than 0.5 mm. Preferably,This fourth layer E802 can be between 0.05 and 0.5 mm thick. The fourth layer E802 of the second interface film 802 can be identical to the third layer E800 of the first interface film 800. The first interface film 800 or the second interface film 802 may include perforations (Figure 12). These perforations may open into the dimple network 86 (particularly at the level of the alveolar cells). The dimple network 86 may include alveolar cells that may be, but are not limited to, polygonal in shape. These polygonal cells may be triangular, quadrangular, pentagonal, or hexagonal, and / or rounded. The dimple network 86 may have a fifth layer E86 that may be less than or equal to 50 mm thick. Preferably, this fifth layer E86 may be between 20 and 40 mm thick. Even more preferably, the fifth thickness E86 can be approximately 30 mm,as proposed in the NIDA honeycomb network. The honeycomb network can be made of metal (such as aluminum), thermoplastic, paper (e.g., impregnated with a phenolic or aramid resin), or cardboard (e.g., impregnated with a phenolic or aramid resin). Preferably, the honeycomb network 86 can be made of amorphous thermoplastic (such as PEI) or semi-crystalline thermoplastic (such as the PAEK family or the polyetherketone family). The honeycomb structure 80 can be made entirely of composite material, particularly when the honeycomb network 86 is made of thermoplastic. Alternatively, the honeycomb structure 80 can be made of composite and metallic material, particularly when the honeycomb network 86 is made of metal and the skins 82, 84 are made of composite material. With reference to Figures 6 to 12,This application will now describe an installation 9 for producing the honeycomb structure 80 described above. Figure 6 illustrates an example of an installation 9 that can operate automatically. This installation 9 may include at least one of the following elements: - a mold 90 (or generally a support), preferably having a flat or curved shape, which serves as a support for producing the honeycomb structure 80, - a draping device 92 for depositing the layers of fibers and / or the interface film(s) 800, 802, - a compaction roller 94 for compacting and applying sufficient pressure to apply (or deposit and adhere) the layers of fibers to each other and / or the interface film(s) 800, 802 with good anchorage to the honeycomb network 86, - a pressure application device (not shown in the figures) for compacting and applying (light) pressure.preferably lower than that of the compaction roller 94, on the cell network 86, - a heating device 96 which allows the first and second stacks 820, 840 to be consolidated by baking (and possibly to heat the interface film(s) 800, 802), - an external heating device (not shown in the figures) which also allows the first and second stacks 820, 840 to be consolidated by baking (and possibly to heat the interface film(s) 800, 802), - a cooling device 98 which allows the mold 90 to be cooled as well as the components on this mold 90 (such as the first stack 820 and the first film 800 with reference to figure 9),and - a perforation device 99 which forms the perforations on the first skin 82 (or second skin 84) and the first interface film 800 (or the second interface film 802) (Figure 12). The mold 90 can be heated by a hot air stream Fc, for example, up to a maximum temperature of approximately 300°C. The mold 90 can be heated by the external heating device. This external heating device can be integrated into the mold 90 to ensure the heating of the mold 90.so that the deposited fiber layers adhere to each other. This external heating device can be self-contained. The mold 90 can be cooled, for example, to a maximum temperature of approximately 20°C. The mold 90 can be cooled by the absence of heating and / or by the cooling device 98. The draping device 92 can move within the installation 9 in a direction SD. This direction SD can be varied, in particular, according to the draping orientation of the fiber layers of the first and / or second stacks 820, 840, and possibly of the interface film(s) 800, 802. The compaction roller 94 can be integrated into the draping device 92. In particular, this draping roller 94 can be located at one end of the draping device 92 (Figures 6 to 12). The pressure-setting device, for example, of the interface film(s) 800,802 can be performed manually by an operator or automatically. This pressurization device can use a flexible membrane (or, in other words, a bladder) to apply a predefined pressure to the cell network 86. The heating device 96 can be integrated into (or attached to) the draping device 92. This heating device 96 allows, in particular, the first and second stacks 820, 840 (and optionally the interface film(s) 800, 802) to be heated by a laser source, a plasma torch, an ultraviolet (UV) lamp, or a flash lamp. The heating device 96 can apply a hot air stream FC which is heated, for example, by the laser source, the plasma torch, or the flash lamp. The heating device 96 can heat up to a maximum temperature of 500°C, in particular to heat the fiber layers and / or the interface film(s). Preferably,The heating device 96 can heat between 300 and 500°C. The external heating device differs, in particular, from the heating device 96 illustrated as an example in Figures 6 to 12. The external heating device integrated into the mold 90 forms a self-contained heating unit. For example, the external heating device can provide under-press heating. The cooling device 98 can be induction-type, forced-air-type, or use a heat transfer fluid. This cooling device 98 can be connected to the mold 90. The perforation device 99 can move within the installation 9 in a direction SP, which may be similar to that of the draping device 92. This perforation device 99 can move in several directions, including the SP direction. With reference to Figures 5 to 12,The present application will now describe a method for manufacturing the honeycomb structure 80 described above. This manufacturing method can be implemented with the installation 9 described above. Figure 5 illustrates steps in the manufacturing method for the honeycomb structure 80, in which optional steps are shown as dashed lines. The manufacturing method according to the invention comprises the steps of: (a) performing the first stacking 820 of several first layers of fibers by draping so as to form the first skin 82, (b) depositing at least the first interface film 800 by draping onto the first skin 82, (c) positioning the honeycomb network 86 on the first interface film 800, (d) optionally depositing at least the second interface film 802 by draping onto the honeycomb network (86),and (e) optionally perform the second stacking 840 of several second layers of fibers by draping to form the second skin 84. At least one of steps (a), (b), (c), (d), and (e) can be performed manually or automatically, in particular with the installation 9. By way of example, automated draping, in particular of at least one of steps (a), (b), (d), and (e), can be carried out according to one of the AFP, ATL, and P&P techniques. With reference to Figure 7, step (a) can be carried out by the draping device 92, which makes it possible to perform the first stacking 820 by draping the first layers of fibers onto the mold 90. During the draping of step (a), the mold 90 can be heated, in particular, up to a maximum temperature of approximately 300°C. This allows for at least partial consolidation by firing of the first stack 820, and / or for maintaining at least partial consolidation by firing of the first stack 820. In step (a),The heating device 96 can heat up to a maximum temperature of approximately 500°C. This also allows for the consolidation, at least partially or entirely, of the first stack 820 by baking (particularly in the case of in-situ consolidation (by baking) described below). Step (a) can be carried out by draping the first fiber layers of the first stack 820 in a direction (or orientation) different from that of the other first fiber layers of this first stack 820. This allows the first stack 820 to be formed with the first fiber layers crossed with each other. This crossed configuration ensures that stresses are transferred in all directions. The crossed configuration can be obtained by draping the first fiber layers in different directions with different orientation angles. For example,The orientation angles of the first fiber layers can be 0° and 90° in the cross-layer configuration. Alternatively, step (a) can be carried out using a quasi-isotropic (QI) draping method. In this case, the first fiber layers can be draped in different directions, for example, with orientation angles chosen from the values ​​of 0°, 45°, -45° (or 135°), and 90°. In step (a), the first fiber layers of the first stack 820 can be deposited as strips. Referring to Figure 8, step (b) can be carried out using the draping device 92, which is similar to that of step (a). One or more first interface film(s) 800 can be deposited during this step (b). During the draping in step (b), the mold 90 can be heated, in particular, up to a maximum temperature of approximately 300°C. This allows the first layer 820 to continue to be consolidated by firing, at least partially.and / or to maintain at least partial curing of the first stack 820. Indeed, heating in step (b) by the external heating device ensures good crystallinity and curing of the first stack 820 draped over the mold 90, and facilitates the change of state of the first deposited interface film 800, which is intended to adhere to the cell network 86. In step (b), the heating device 96 can heat, in particular, up to a maximum temperature of approximately 500°C. This also allows continued curing of the first stack 820 to ensure good cohesion and crystallinity (or other material properties) of the fiber layers.and / or to maintain the consolidation by at least partial baking of the first stack 820. This step (b) also makes it easier to change the state of the interface film 800 deposited for easy adhesion of the interface film 800 to the first stack 820. The first interface film 800 can be deposited in strips. The first skin 82 and the first interface film 800 obtained in step (b) can be cooled with the cooling device 98. This can be done before (and possibly during) step (c) of positioning the dimple array 86. For this purpose, the mold 90, comprising the first skin 82 and the first interface film 800 draped and stacked on this first skin 82, can be cooled with the cooling device 98. This makes it possible, for example, to avoid deforming and / or damaging the dimple array 86 when it is positioned on the first interface film 800. Advantageously,The first skin 82 and the first interface film 800 can be cooled to a temperature of approximately 20°C (for example, with a tolerance of approximately + / - 1°C). Referring to Figure 9, step (c) can be performed on the mold 90, which includes the first stack 820 and the first interface film 800, both of which are cooled. Step (c) can be performed manually by an operator. Alternatively, step (c) can be performed automatically. For this purpose, the installation 9 can further include a device for applying the cell array 86 (not shown in the figures). This application device can be a gripping clamp allowing the cell network 86 to be positioned on the first interface film 800. Steps (a), (b) and (c), as illustrated without limitation in Figures 6 to 9, allow the first skin 82 covering the cell network 86 to be produced.so as to form either the semi-open alveolar structure 80 of Figure 2, or a part of the alveolar structure 80 of Figures 3 and 4. Steps (d) and (e), as illustrated non-limitingly in Figures 10 and 11, are described below and enable the creation of the second skin 84 also covering the alveolar network 86, so as to form the alveolar network 86 arranged between the first 82 and second 84 skins of the alveolar structure 80 of Figures 3 and 4. With reference to Figure 10 and optionally, step (d) can be carried out by the draping device 92. One or more second interface film(s) 802 can be deposited during this step (d). During the draping in step (d), the mold 90 can be heated, for example, to a maximum temperature of approximately 300°C. This allows, in particular, for at least partial curing of the first stack 820. In step (b),The heating device 96 can heat up to a maximum temperature of approximately 500°C. The hot air flow Fc from the mold 90 and / or the heating device 96 heats the first and second interface films 800, 802, notably through a radiant effect across the first stack 820, the first interface film 800, and the honeycomb structure 86. This allows the formation of adhesion menisci 886a, 886b connecting the first and second interface films 800, 802 to the honeycomb structure 86. The adhesion menisci 886a, 886b can be formed between the side walls of the honeycomb cells of the honeycomb structure 86 and the interface films 800, 802. The second interface film 802 can be deposited in strips. With reference to Figure 11 and optionally,Step (e) can be carried out by the draping device 92, which enables the creation of the second stack 840 by draping the second layers of fibers over the second interface film 802. During the draping in step (e), the mold 90 can be heated, in particular, up to a maximum temperature of approximately 300°C. This notably allows for maintaining the curing of the first stack 820, the first interface film 800, and the second interface film 802 with the cell network 86. In step (a), the heating device 96 can be heated, in particular, up to a maximum temperature of approximately 500°C. This also allows for at least partial curing of the second stack 840, or for its complete curing (particularly in the case of in-situ curing). The heating of the first and second interface films 800,802, through the flow of hot air Fc from the heating device 96 and / or the mold 90, enhances the formation of the gripping menisci 886a, 886b. Step (e) can be carried out by draping the second layers of fibers of the second stack 820 in a different direction than the other second layers of fibers in this second stack 840. This allows the second stack 840 to be formed with the second layers of fibers crossed, notably to ensure load transfer in all directions. Similar to the first stack 820, the second layers of fibers can be draped in different directions, with the orientation angles of the second fiber layers being chosen from the values ​​of 0°, 45°, -45° (or 135°), and 90°. In step (e), the second layers of fibers of the second 840 stack can be deposited in strip form. At least one of the steps (a), (b), (c),(d) and (e) include a compaction substep (ai, bi, ci, di, ei) of the fiber layers of the first and / or second stacks 820, 840 and of the first and / or second interface films 800, 802. This or these compaction substeps (ai, bi, di, ei) can be carried out with the compaction roller 94. The compaction substep (ci) can be carried out by applying pressure to achieve compaction, preferably lighter than that achieved by the compaction roller 94. The draping and compaction of at least one of the first and second stacks 820, 840 and of at least one of the first and second interface films 800, 802 can be carried out simultaneously. Steps (a) and (e) may each include a substep of firing (aii, eii), or in other words, consolidating by firing, the first and second stacks 820, 840 to form the first and second skins 82, 84 respectively. According to a first embodiment,at least one of the sub-steps (aii, eii) of firing can (or can) be carried out during the draping of the first and / or second stacks 820, 840, as illustrated in figures 7 and 11. In other words, the draping and firing of the first stack 820 and / or the second stack 840 can be carried out simultaneously. This substep or these substeps (aii, eii) can be carried out with the heating device 96. In the substep or substeps (aii, eii), the first and / or second stacks 820, 840 can be heated to perform curing, for example by the heating device 96. The heating device 96 can be self-heating and in this case allows the first 820 and / or second 840 stacks (and possibly the first interface film(s) 800, 802 deposited) to be cured in situ (by curing). According to a second embodiment, at least one of the substeps (aii,eii) The curing (or in other words, curing consolidation) step can be carried out after the draping of the first and / or second layers 820, 840. This substep or these substeps (aii, eii) can be carried out with the external heating device. In this configuration, the first and / or second layers 820, 840 can be heated to carry out curing (by curing) in situ, particularly when the external heating device is self-heating. The process according to the invention may further include a perforation step (f) of one of the first and second skins 82, 84. This step (f) can be carried out after step (e). Step (f) may also include the perforation of one of the first and second interface films 800,802. Step (f) enables the formation of the honeycomb structure 80 with an acoustic function. Figure 12 illustrates, in a non-limiting manner, the perforation of the first skin 82 and the first interface film 800. In this configuration, the second skin 84 can be solid without perforations. In an alternative not shown in the figures, the second skin 82 and the second interface film 802 can be perforated to form the honeycomb structure in either a semi-open or closed type. In this alternative, the first skin 82 can be solid without perforations.

Claims

CLAIMS 1. A method for manufacturing a honeycomb structure (80) for a part (8), in particular for an aircraft turbomachine (10), this honeycomb structure (80) comprising a honeycomb array (86), a first skin (82) of composite material covering the honeycomb array (86), and optionally a second skin (84) of composite material and arranging the honeycomb array (86) between said first and second skins (82, 84), the method being characterized in that it comprises the steps of: (a) carrying out a first stacking (820) of several layers of fibers by draping so as to form the first skin (82), (b) depositing at least one first interface film (800) by draping onto the first skin (82), (c) positioning the honeycomb array (86) on the first interface film (800), (d) optionally depositing at least a second interface film (802) by draping over the honeycomb network (86),and (e) optionally perform a second stacking (840) of several layers of fibers by draping so as to form the second skin (84), wherein the fiber layers of at least one of the first and second stacks (820, 840) comprise fibers pre-impregnated with a first thermoplastic material and at least one of the first and second interface films (800, 802) comprises a second thermoplastic material, and wherein the second thermoplastic material has a softening temperature lower than that of the first thermoplastic material.

2. A manufacturing method according to claim 1, characterized in that at least one of the steps (a), (b), (c), (d), and (e) comprises a substep of compacting (ai, bi, ci, di, ei) the fiber layers of the first and / or second stacks (820, 840) and of the first and / or second interface films (800, 802),such as with a compaction roller (94) which is for example integrated into a draping device (92) for the sub-steps (ai, bi, di, ei), or with a pressure device for the sub-step (ci).

3. A manufacturing method according to claim 1 or 2, characterized in that steps (a) and (e) each comprise a substep of baking (aii, eii) the first and second stacks (820, 840) to form the first and second skins (82, 84), respectively.

4. A manufacturing method according to claims 2 and 3, characterized in that at least one of the baking substeps (aii, eii) is carried out during the draping of the first and / or second stacks (820, 840) with a heating device (96) integrated into the draping device (92), wherein the first and / or second stacks (820, 840) are heated, for example, by a laser source, a plasma torch, an ultraviolet lamp, or a flash lamp. 5.A method according to claim 3, characterized in that at least one of the cooking substeps (aii, eii) is carried out after draping the first and / or second stacks (820, 840) with an external heating device, wherein the first and / or second stacks (820, 840) are heated, for example, in a heating device.

6. A manufacturing method according to any one of claims 1 to 5, characterized in that at least one of the steps (a) and (e) is carried out by draping at least one of the fiber layers of the first and / or second stacks (820, 840) in a direction different from that of the other fiber layers of the corresponding stack (820, 840). 7.A manufacturing method according to any one of claims 1 to 6, characterized in that, prior to step (c), the first skin (82) and the first interface film (800) obtained in step (b) are cooled with a cooling device (98), for example, an induction type, a forced-air type, or with a heat transfer fluid. A manufacturing method according to claim 7, characterized in that the first skin (82) and the first interface film (800) are cooled to a temperature of approximately 20°C.

9. A manufacturing method according to any one of claims 1 to 8, characterized in that at least one of the first and second skins (82, 84) comprises perforations (822), wherein the method further comprises a perforation step (f) of one of the first and second skins (82, 84) which is carried out after step (e).

10. A manufacturing method according to any one of claims 1 to 9, characterized in that the honeycomb structure (86) is made of metal, such as aluminum, thermoplastic, paper, or cardboard, wherein the paper or cardboard is, for example, impregnated with a phenolic or aramid resin.

11. A manufacturing method according to any one of claims 1 to 10, characterized in that the first interface film (800) has a thickness (E800) that is less than 0.5 mm, preferably between 0.05 and 0.5 mm. 12.A manufacturing method according to any one of claims 1 to 11, characterized in that the second interface film (802) has a thickness (E802) which is less than 0.5 mm, preferably between 0.05 and 0.5 mm.

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