Method for manufacturing a multicellular panel by radiative welding

Abstract

The invention relates to a method for manufacturing a multicellular panel (500) comprising a cellular structure (300) and a first skin (100) made of a thermoplastic composite material, the cellular structure (300) comprising a plurality of walls (330) extending in a first direction (X) between a first face (310) and a second face (320) of the cellular structure (300), the method comprising a first radiative welding operation in which the first skin (100) is welded to the first face (310) of the cellular structure (300), the first radiative welding operation comprising a step of stacking the cellular structure (300) on the first skin (100), followed by a step of heating the first skin (100) through the cellular structure by means of a radiative source (600, 700), then a step of pressing the cellular structure (300) against the first skin (100), the radiative source (600, 700) being arranged facing the second face (320) of the cellular structure (300), and the first face of the cellular structure (310) being arranged facing the first skin (100).

Description

Description Title of the invention: Method for manufacturing a multicellular panel by radiative welding Technical Field

[0001] The present invention relates to the general field of structures based on composite materials and thermoplastic polymers. More particularly, it relates to multicellular panels comprising composite materials and at least one thermoplastic polymer. Previous technique

[0002] Climate change is a major concern for numerous legislative and regulatory bodies worldwide. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by different countries. In particular, an ambitious standard applies to both new types of aircraft and those already in operation, requiring the implementation of technological solutions to bring them into compliance with current regulations. Civil aviation has been actively contributing to the fight against climate change for several years now.

[0003] Technological research efforts have already led to very significant improvements in the environmental performance of aircraft. The Applicant takes into account the factors impacting all phases of design and development in order to obtain aeronautical components and products that are less energy-intensive, more environmentally friendly, and whose integration and use in civil aviation have moderate environmental impacts, with the aim of improving the energy efficiency of aircraft.

[0004] The Applicant works in research and development on the weight reduction of devices, particularly through the materials used.

[0005] Multicellular panels made from thermoplastic composite materials are increasingly used in the aviation industry because they allow for parts with a lower overall mass than these The same components, when made of metallic material, offer at least equivalent, if not superior, mechanical strength. Multicellular panels can be used, for example, in acoustic panels for engine nacelles, in inter-blade platforms, or in engine casings, etc.

[0006] In some prior art methods, multicellular panels are made by bonding or co-firing a honeycomb structure between two skins of a composite material. The honeycomb structure typically includes a honeycomb (NIDA) or cone-shaped structure.

[0007] Manufacturing by bonding or co-baking has the disadvantage of generating several defects in the multicellular panel.

[0008] During bonding, the adhesive can flow along the walls of the honeycomb structure, generating bubbles or forming menisci at the joints. Furthermore, the adhesive can seal openings in the honeycomb structure, which is particularly problematic when multicellular panels are used as acoustic panels.

[0009] Co-curing can cause marking of composite material skins. This phenomenon is known as "telegraphing." This manufacturing method can also lead to deformation of the honeycomb structure under the pressure of co-curing. Furthermore, co-curing involves heat treatment lasting several hours, making the process slow.

[0010] All these defects significantly reduce the mechanical and / or acoustic performance of multicellular panels.

[0011] Other manufacturing methods for multicellular panels include assembling the honeycomb structure to the skins by induction, resistance, or ultrasonic welding. However, these methods are not suitable for manufacturing such panels.

[0012] Induction welding and resistance welding involve the introduction of a metallic element at the interface between the honeycomb structure and the skins. This generates a significant increase in the final mass of the multicellular panel. Furthermore, the presence of the metallic element degrades the adhesion between the skins and the honeycomb structure.

[0013] Ultrasonic welding involves applying high forces to the assembly by the sonotrode and generally results in deformation of the cellular component. Description of the invention

[0014] The main purpose of the present invention is therefore to propose a solution for the manufacture of a multicellular panel which does not present the aforementioned disadvantages.

[0015] To this end, the invention proposes a method for manufacturing a multicellular panel comprising a honeycomb structure and a first skin made of a thermoplastic composite material, the honeycomb structure comprising a plurality of walls extending in a first direction between a first face and a second face of the honeycomb structure, the method comprising a first radiative welding in which the first skin is welded to the first face of the honeycomb structure.The process is characterized in that the first radiative welding comprises a step of stacking the honeycomb structure on the first skin, followed by a step of heating the first skin through the honeycomb structure via a radiative source, then a step of pressing the honeycomb structure against the first skin, the radiative source being positioned opposite the second face of the honeycomb structure during the heating step, and the first face of the honeycomb structure being opposite the first skin and in that the thermoplastic composite material of the honeycomb structure is transparent to the radiation of the radiative source while the thermoplastic composite material of the first skin is capable of absorbing the radiation of said radiative source.

[0016] This manufacturing process ensures a robust weld between the first skin and the honeycomb structure without increasing the size of the multicellular panel. Unlike resistance welding and welding by With induction heating, it is not necessary to introduce an element at the interface between the honeycomb structure and the skin. The presence of such an element makes the panel bulkier and can degrade the adhesion between the honeycomb structure and the first skin. Furthermore, the first skin does not need to be in contact with the radiant source to be heated. This is a significant advantage because it allows for easy heating of the entire surface of the first skin to be welded. Positioning the radiant source on the honeycomb structure already laid on the first skin also saves time in panel manufacturing. The skin and honeycomb structure are assembled in a single step. This also allows for greater flexibility in positioning the honeycomb structure before welding.

[0017] Furthermore, since the thermoplastic composite material of the honeycomb structure is transparent to the radiation from the radiative source, there is no risk of deterioration of the honeycomb structure during welding.

[0018] Thus, it is possible to obtain a multicellular panel with good mechanical properties, in particular thanks to the robustness of the bond between the first skin and the alveolar structure.

[0019] Depending on a particular characteristic, the radiative source used for the first radiative welding may include an infrared lamp or a laser source.

[0020] Infrared lamps can simultaneously heat large areas up to 1 m² 2 Laser sources allow for localized heating of a surface and possess a high power density. The heating rate with a laser source is very high.

[0021] The choice between laser and infrared lamp will depend on the total surface area of ​​the room to be heated.

[0022] According to a particular feature, the process may further include the placement of a first thermoplastic film between the first skin and the first face of the alveolar structure before the heating step of the first radiative welding.

[0023] The presence of such a film helps to improve adhesion between the first skin and the alveolar structure.

[0024] According to a particular feature, the process may further include a second radiative welding in which a second skin of a thermoplastic composite material is heated via a radiative source and welded onto the second face of the honeycomb structure.

[0025] This results in a multicellular panel with a sandwich structure in which the honeycomb structure is positioned between the first and second skins. Such a panel exhibits good mechanical properties due to the robust bonds between the skins and the honeycomb structure.

[0026] Depending on a particular characteristic, the radiative source used for the second radiative welding may include an infrared lamp or a laser source.

[0027] Infrared lamps can simultaneously heat large areas up to 1 m² 2 Laser sources allow for localized heating of a surface and possess a high power density. The heating rate with a laser source is very high.

[0028] The choice between laser and infrared lamp will depend on the total surface area of ​​the room to be heated.

[0029] Depending on a particular characteristic, the first and second welding can be carried out simultaneously.

[0030] This allows for simpler and faster manufacturing of the multi-cell panel. Heating both skins of thermoplastic composite material simultaneously reduces the number of process cycles—one to heat the first skin and another to heat the second. This makes it possible to manufacture the multi-cell panel in a single cycle. This is particularly advantageous when the surfaces to be welded are large.

[0031] Depending on a particular characteristic, the thermoplastic composite material of the first skin and / or second skin may comprise a thermoplastic polymer loaded with carbon fibers or carbon black and chosen from polyetherketoneketones, polyetheretherketones, polyaryletherketones, polyphenylene sulfides, polyetherimides or a mixture thereof.

[0032] This type of material absorbs the waves emitted by the radiative source, thus maximizing heat absorption. This facilitates heating the first and / or second skin during the implementation of the process.

[0033] According to a particular feature, the process may further include the placement of a second thermoplastic film on the second face of the honeycomb structure before the second radiative welding.

[0034] The presence of such a film helps to improve adhesion between the second skin and the alveolar structure. Brief description of the drawings

[0035] [Fig. 1] Figure 1 illustrates the flowchart of the steps of a first embodiment of a process according to the invention,

[0036] [Fig. 2] Figure 2 schematically represents the process of Figure 1,

[0037] [Fig. 3] Figure 3 illustrates the flowchart of the steps of a second embodiment of a process according to the invention,

[0038] [Fig. 4] Figure 4 schematically represents the process of Figure 3. Description of the implementation methods

[0039] The invention applies generally to multicellular panels, in particular but not exclusively to multicellular panels having a sandwich structure.

[0040] Figures 1 and 2 illustrate a first embodiment of the process according to the invention. The process comprises a first cycle Cyl and a second cycle Cy2. The multicellular panel 500 produced in this example comprises a first skin 100 made of a thermoplastic composite material, a second skin 200 made of a thermoplastic composite material, and a honeycomb structure 300.

[0041] The first skin 100 comprises a first face 110 and a second face 120. The second skin 200 comprises a first face 210 and a second face 220.

[0042] The 500 multicellular panel also includes a first thermoplastic film 430 and a second thermoplastic film 460. The first thermoplastic film 430 has a first face 410 and a second face 420. The second thermoplastic film 460 has a first face 440 and a second face 450.

[0043] The alveolar structure 300 comprises a first face 310, a second face 320, a plurality of walls 330 and a plurality of orifices 340. The walls 330 extend along a first direction X between the first face 310 of the alveolar structure 300 and the second face 320 of the alveolar structure 300. The first and second faces 110, 120 of the first skin 100 extend perpendicularly to the first direction X.

[0044] According to one variant, the 300 alveolar structure may include a cone structure.

[0045] The first and second faces 210, 220 of the second skin 200 extend perpendicularly to the first direction X.

[0046] In one embodiment, the first skin 100 or the second skin 200 can be perforated.

[0047] The first and second faces 410 and 420 of the first thermoplastic film 430 extend perpendicularly to the first direction X. The first and second faces 440 and 450 of the second thermoplastic film 460 extend perpendicularly to the first direction X.

[0048] We now describe an example of the implementation of the first cycle Cyl of the manufacturing process for a multicellular panel. In a first step El, the first face 410 of the first thermoplastic film 430 is placed on the first face 110 of the first skin 100.

[0049] The arrangement of the first thermoplastic film 430 improves the adhesion between the first face 310 of the alveolar structure 300 and the first skin 100.

[0050] The presence of the first thermoplastic film 430 does not limit the invention in any way. Nor is the presence of step El a limiting factor.

[0051] In one embodiment, the multicellular panel 500 is devoid of the first thermoplastic film 430. In this case, the process is devoid of step El. In yet another embodiment, the first face 110 of the first skin 100 is covered with the first thermoplastic film 430 before the process is implemented.

[0052] According to a particular characteristic, the first thermoplastic film 430 comprises a material selected from polyetherketoneketones, polyetheretherketones, polyaryletherketones, polyphenylene sulfides, polyetherimides or a mixture thereof.

[0053] The process is followed by a stacking step E2 during which the first face 310 of the honeycomb structure 300 is placed on the second face 420 of the first thermoplastic film 430.

[0054] When multicellular panel 500 is devoid of the first thermoplastic film 430, the first face 310 of the honeycomb structure 300 is arranged on the first face 110 of the first skin 100 during the stacking step E2.

[0055] Next the process is followed by a first radiative welding step E3. During the first radiative welding E3, a radiative source 600 is placed opposite the second face 320 of the alveolar structure 300, as illustrated in figure 2a.

[0056] The radiative source 600 emits radiation 640 of a predefined wavelength. The honeycomb structure 300 transmits the radiation 640 from the radiative source 600 to the first thermoplastic film 430 and the first skin 100, through the walls 330 and the openings 340. Indeed, the honeycomb structure 300 is made of a thermoplastic composite material that is transparent to the radiation 640. of the radiative source. In other words, the thermoplastic composite material of the alveolar structure 300 is capable of transmitting the waves 640 emitted by the radiative source 600. Thus, the first skin 100 can be heated during the first radiative heating.

[0057] The thermoplastic composite material of the 300 honeycomb structure can be chosen from polyetherketoneketones, polyetheretherketones (PEEK), polyaryletherketones, polyphenylene sulfides, polyetherimides (PEI) or a mixture of these loaded with glass fibers.

[0058] According to one variant, the thermoplastic composite material of the 300 honeycomb structure can be devoid of carbon fibers.

[0059] The first skin 100 comprises a thermoplastic composite material capable of absorbing the radiation emitted by the radiative source 600. This ensures optimal heating of the first face 110 of the first skin 100.

[0060] The first skin thermoplastic composite material 100 may comprise a thermoplastic polymer loaded with carbon fibers or carbon black and selected from polyetherketoneketones, polyetheretherketones, polyaryletherketones, polyphenylene sulfides, polyetherimides or a mixture thereof.

[0061] When the first skin 100 is heated, the first face 110 of the first skin 100 and the first thermoplastic film 430 melt. The second face 120 of the first skin 100 and the rest of the first skin 100 do not melt.

[0062] In the example shown in Figure 2a, the radiant source 600 comprises four infrared lamps. The number of infrared lamps is not limited. In one embodiment, the radiant source 600 may comprise a number of infrared lamps other than four.

[0063] The presence of infrared lamps is not limiting. In one embodiment, the radiative source 600 may comprise a laser source or a plurality of laser sources.

[0064] During the first E3 radiative welding, the first skin 100 is heated to a temperature between 280°C and 400°C.

[0065] Next, the process is followed by a removal step E4 of the radiative source 600. This is followed by a first pressing step E5 in which the first face 310 of the honeycomb structure 300 is pressed against the second face 420 of the first thermoplastic film 430, as illustrated in Figure 2b. For this purpose, a contact pressure P is applied to the second face 320 of the honeycomb structure 300. This pressure is applied along the first direction X but in the opposite direction. The panel, having a first skin 100 and a honeycomb structure 300, is obtained at the end of the pressing step E5, as illustrated in Figure 2c.

[0066] According to one variant, the first pressing step E5 can be carried out at room temperature.

[0067] According to another variant, the first pressing stage E5 can be carried out at a predetermined temperature and continuously controlled to ensure controlled cooling of the first skin 100 and the alveolar structure 300.

[0068] When multicellular panel 500 is devoid of the first thermoplastic film 430, the first face 310 of the honeycomb structure 300 is pressed against the first face 110 of the first skin 100 during the first pressing step E5.

[0069] The contact pressure P applied during the first pressing step E5 is between 0.05 MPa and 0.5 MPa.

[0070] Steps E1 to E5 correspond to the first Cyl cycle of the process illustrated in figures 1 and 2.

[0071] We now describe an example of the implementation of the manufacturing process of a multicellular panel comprising a second Cy2 cycle in addition to the first Cyl cycle.

[0072] The process comprises the steps described above followed by the following steps. A step E6 of laying a second thermoplastic film 460 onto the second face 320 of the honeycomb structure 300. The laying of a second thermoplastic film 460 improves adhesion between the second face 320 of the alveolar structure 300 and the second skin 200.

[0073] The presence of the second thermoplastic film 460 and the presence of step E6 are in no way limiting.

[0074] In another embodiment, the multicellular panel 500 is devoid of the second thermoplastic film 460. In this case, the process is devoid of step E6. In yet another embodiment, the first face 210 of the second skin 200 is covered with the second thermoplastic film 460 before the implementation of the process according to the invention.

[0075] Next, the process is followed by a second radiative welding E7 during which the radiative source 600 is positioned opposite the first face 210 of the second skin 200, as illustrated in Figure 2d. The radiative source 600 emits radiation 640 of a predefined wavelength, which heats the second skin 200. The wavelength of the radiation 640 can be between 0.7 pm and 2.5 pm.

[0076] The second skin 200 comprises a thermoplastic composite material capable of absorbing the radiation emitted by the radiative source 600. This ensures optimal heating of the first face 210 of the second skin 200.

[0077] According to a particular characteristic, the thermoplastic composite material of the second skin 200 may comprise a thermoplastic polymer loaded with carbon fibers or carbon black and selected from polyetherketoneketones, polyetheretherketones, polyaryletherketones, polyphenylene sulfides, polyetherimides or a mixture thereof.

[0078] When the second skin 200 is heated, the first face 210 of the second skin 200 melts. The second face 220 of the second skin 200 and the rest of the second skin 200 do not melt.

[0079] The 600 radiant source used for the first radiant weld E3 can be used for the second radiant weld E7, as illustrated in Figure 2d. Using the same radiant source for both the first and second radiant welds is not a limitation. In a mode of In implementation, the first radiative welding can be carried out with a first radiative source and the second radiative welding with a second radiative source.

[0080] The radiant source 600 used for the second radiant weld E7 can include an infrared lamp or a laser source. In the example shown in Figure 2d, the second weld E7 is performed using a radiant source 600 comprising four infrared lamps 610. The number of infrared lamps is not limited.

[0081] During the second E7 radiative welding, the second skin 200 is heated to a temperature between 280°C and 400°C.

[0082] Next, the process is followed by a removal step E8 of the radiative source 600. This is followed by a second pressing step E9 in which the first face 210 of the second skin 200 is pressed against the second face 450 of the second thermoplastic film 460, as illustrated in Figure 2e. For this purpose, a contact pressure P is applied to the second face 220 of the second skin 200. This pressure is applied along the first direction X but in the opposite direction.

[0083] According to one variant, the second pressing stage E9 can be carried out at room temperature.

[0084] According to another variant, the second pressing stage E9 can be carried out at a predetermined temperature and continuously controlled to ensure controlled cooling of the second skin 200 and the alveolar structure 300.

[0085] The contact pressure P applied during the second pressing stage E9 is between 0.05 MPa and 0.5 MPa.

[0086] Steps E6 to E9 correspond to the second cycle Cy2 of the process illustrated in figures 1 and 2. The 500 multicellular panel obtained in the second example is illustrated in figure 2f.

[0087] When the multicellular panel 500 is devoid of the second thermoplastic film 460, the first face 210 of the second skin 200 is pressed against the second face 320 of the honeycomb structure 300 during the second pressing step E9.

[0088] The presence of the second cycle does not limit the invention. In one embodiment, the process may comprise only the first cycle. Such a process makes it possible to obtain a multicellular panel comprising a first skin and a honeycomb structure.

[0089] Figures 3 and 4 illustrate a second example of a process according to the invention. In this case, the process comprises a single cycle.

[0090] In the example illustrated in Figures 3 and 4, the process comprises the same steps E1, E2, and E9 as the process illustrated in Figures 1 and 2 (see Figure 4). Instead of step E3, the process includes a step E30 in which the first and second radiative welds are performed simultaneously, as illustrated in Figure 4b. The first and second welds are performed using a radiative source 700. During step E30, the first and second skins of a thermoplastic composite material 100, 200 are heated. During heating, the first faces 110, 210 of the first and second skins 100, 200, the first thermoplastic film 430, and the second thermoplastic film 460 melt.

[0091] The radiative source 700 comprises a first group of infrared lamps 710 and a second group of infrared lamps 720. The first group of infrared lamps 710 is positioned opposite the second face 450 of the second thermoplastic film 460, which was previously placed on the second face 320 of the honeycomb structure 300 in step E22. The second group of infrared lamps 720 is positioned opposite the first face 210 of the second skin 200, as illustrated in Figure 4b. The first group of infrared lamps 710 emits a first radiation 740 of a predefined wavelength, and the second group of infrared lamps 720 emits a second radiation 750 of a predefined wavelength. The wavelength of the first radiation 740 can be between 0.7 pm and 2.5 pm. The wavelength of the second 750 radiation can be between 0.7 pm and 2.5 pm.The first 740 radiation and the second 750 radiation may have the same wavelength.

[0092] The first group of infrared lamps 710 heats the first skin 100 and the second group of infrared lamps 720 heats the second skin 200.

[0093] When the process lacks the positioning step E1 of the first thermoplastic film 430, the first group of infrared lamps 710 is positioned opposite the second face 320 of the honeycomb structure 300. When the process lacks the positioning step E22 of the second thermoplastic film 460, the second group of infrared lamps 720 is positioned opposite the first face 210 of the second skin 200.

[0094] Next, the process is followed by a removal step E40 of the radiative source 700. The process is followed by the pressing step E9 described previously. The 500 multicellular panel obtained in the second example is illustrated in figure 4d.

Claims

Demands

1. A method for manufacturing a multicellular panel (500) comprising a honeycomb structure (300) and a first skin (100) made of a thermoplastic composite material, the honeycomb structure (300) having a plurality of walls (330) extending in a first direction (X) between a first face (310) and a second face (320) of the honeycomb structure (300), the method comprising a first radiative welding in which the first skin (100) is welded to the first face (310) of the honeycomb structure (300), the method being characterized in that the first radiative welding comprises a step of stacking the honeycomb structure (300) onto the first skin (100), followed by a step of heating the first skin (100) through the honeycomb structure via a radiative source (600, 700), and then a step of pressing the structure alveolar (300) against the first skin (100),the pressing step being carried out at a predetermined and continuously controlled temperature, the radiative source (600, 700) being positioned opposite the second face (320) of the honeycomb structure (300) during the heating step, and the first face of the honeycomb structure (310) being opposite the first skin (100), and in that the thermoplastic composite material of the honeycomb structure is transparent to the radiation of the radiative source while the thermoplastic composite material of the first skin is capable of absorbing the radiation of said radiative source.

2. A method according to claim 1, wherein the radiative source (600, 700) used for the first radiative welding comprises an infrared lamp or a laser source.

3. Method according to claim 1 or 2, further comprising the disposition of a first thermoplastic film (430) between the first skin (100) and the first face (310) of the honeycomb structure (300) before the heating step of the first radiative welding.

4. A method according to any one of claims 1 to 3, further comprising a second radiative welding in which a second skin a thermoplastic composite material (200) is heated via a radiative source (600, 700) and welded onto the second face (320) of the honeycomb structure (300).

5. A method according to claim 4, wherein the radiative source (600, 700) used for the second radiative welding comprises an infrared lamp or a laser source.

6. A method according to claim 4 or 5, wherein the first weld and the second weld are carried out simultaneously.

7. A method according to any one of claims 4 to 6, wherein the thermoplastic composite material of the first skin (100) and / or the second skin (200) comprises a thermoplastic polymer loaded with carbon fibers or carbon black and selected from polyetherketoneketones, polyetheretherketones, polyaryletherketones, polyphenylene sulfides, polyetherimides, or a mixture thereof.

8. A method according to any one of claims 4 to 7, further comprising the disposition of a second thermoplastic film (460) on the second face (320) of the honeycomb structure (300) prior to the second radiative welding.

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