Manufacturing an acoustic panel by laser welding

Abstract

The invention proposes a method for manufacturing an acoustic panel (100) comprising the assembly of at least one acoustic component (120) with an acoustic skin (110), the acoustic component (120) comprising a plurality of hollow acoustic elements (121) having a shape that gradually narrows between a base (121a) and an apex (121b), the bases (121a) of the hollow acoustic elements (121) being connected to one another by connecting edges (122), the method being characterised in that the connecting edges (122) of the acoustic component (120) are made of a transparent thermoplastic material and in that the acoustic skin (110) is made of an opaque thermoplastic material, and in that the connecting edges (122) are attached to the acoustic skin (110) by laser welding.

Description

Description Title of the invention: Manufacture of an acoustic panel by laser welding Technical Field

[0001] The present invention relates to the general field of acoustic attenuation structures. It relates more particularly to acoustic attenuation structures used to reduce noise produced in aircraft engines such as in gas turbines or their exhausts. Prior art

[0002] Acoustic attenuation panels typically consist of an acoustic surface plate or skin permeable to the acoustic waves that are to be attenuated and a reflective solid plate or skin called a "closing plate", a multicellular body being arranged between these two skins. The multicellular body is generally constituted by a set of partitions, for example in the form of a honeycomb, delimiting a plurality of cells. In a well-known manner, such panels form Helmholtz-type resonators which make it possible to attenuate acoustic waves in a certain frequency range. Acoustic attenuation panels of this type are described in particular in documents US 5,912,442 and GB 2,314,526.

[0003] These acoustic attenuation panels are limited to simple cell shapes such as those of NIDA-type honeycomb cells. Consequently, when one wishes to treat low frequencies, it is necessary to resort to thick multi-cellular bodies.

[0004] One solution to handle low frequencies without resorting to an overly thick multicellular body is to place hollow acoustic elements, for example open cone truncates, in the cells of the multicellular body as described in document FR 3 082 987.

[0005] To manufacture such an acoustic panel, it is therefore necessary to assemble the acoustic skin with the hollow acoustic elements, the acoustic elements hollow with the multicellular body and the multicellular body with the possible closing skin.

[0006] Glue can be used to join the hollow acoustic elements to the acoustic skin. However, there is a high risk of the glue falling inside the hollow acoustic elements. The presence of glue inside the hollow acoustic elements would lead to a deterioration in acoustic performance.

[0007] The assembly of hollow acoustic elements with the acoustic skin can also be carried out by conduction welding. However, the risk of deforming the hollow acoustic elements under the effect of the heat provided by conduction to carry out the welding is significant, while such deformation would lead to a degradation of the acoustic performance. This risk of deformation under the effect of heat is all the higher when the hollow acoustic elements are thin and thin. Statement of the invention

[0008] The present invention aims to remedy the aforementioned drawbacks by proposing a solution for assembling the hollow acoustic elements to the acoustic skin without risking reducing the acoustic performance of the acoustic panel obtained.

[0009] To this end, the invention proposes a method for manufacturing an acoustic panel comprising the assembly of at least one acoustic component with an acoustic skin, said acoustic component comprising a plurality of hollow acoustic elements having a shape gradually narrowing between a base and a top, the bases of the hollow acoustic elements being connected to each other by connecting edges, the assembly comprising:

[0010] - positioning the acoustic skin in contact with the connecting edges of said acoustic component,

[0011] - maintaining the acoustic skin in position against the connecting edges, and

[0012] - fixing the connecting edges of the acoustic component to the acoustic skin while maintaining the position,

[0013] the method being characterized in that the connecting edges of the acoustic component are made of a transparent thermoplastic material for at least one determined laser wavelength and in that the acoustic skin is made of an opaque thermoplastic material for at least the determined laser wavelength, and in that the fixing of the connecting edges to the acoustic skin comprises the emission of a laser beam having the determined wavelength and passing through the connecting edges until reaching the contact interface between the connecting edges and the acoustic skin so as to cause localized heating at the level of said contact interface resulting in the welding of the connecting edges to the acoustic skin.

[0014] Thus, by choosing an opaque material for the acoustic skin and a transparent material for the hollow acoustic elements, it is possible to laser weld the hollow acoustic elements with the acoustic skin. This welding method has the advantage of being very localized, thus greatly reducing the risk of deformation of the hollow acoustic elements.

[0015] Furthermore, compared to solutions using glue to fix the connecting edges of the acoustic component to the acoustic skin, it prevents the glue from falling into the hollow acoustic elements and thus reducing the acoustic performance of the acoustic panel.

[0016] By material "transparent for at least one determined laser wavelength" is meant here a material allowing at least said determined wavelength in the form of a laser to pass through the material. By material "opaque for at least the determined laser wavelength" is meant here a material preventing the passage of said determined wavelength in the form of a laser through the material.

[0017] For example, the transparent material may allow at least wavelengths between 800 nm and 3000 nm to pass through, for example between 1500 nm and 2000 nm. For example, the opaque material may prevent the passage of wavelengths between 800 nm and 3000 nm, for example between 1500 nm and 2000 nm.

[0018] In the remainder of the description, for reasons of simplification, the term “transparent” will designate “transparent for at least one determined laser wavelength” and the term “opaque” will designate “opaque for at least the determined laser wavelength”.

[0019] The welding used can, for example, be of the LSW type for “longitudinal seam welding” in English.

[0020] According to a particular embodiment of the invention, the acoustic skin is held in position against the connecting edges of the acoustic component during fixing by means of a transparent material cover placed under vacuum, the cover being configured to apply pressure to the tops of the hollow acoustic elements of the acoustic component so that the connecting edges of the acoustic component are held against the acoustic skin, the laser beam passing through said cover before passing through the connecting edges during fixing.

[0021] This improves the positioning of the acoustic component against the acoustic skin, particularly when the acoustic component is large or has a complex three-dimensional shape. This method also allows the acoustic component to be pressed against the acoustic skin, which facilitates laser welding. In addition, the repeatability of the positioning is improved.

[0022] According to another particular embodiment of the invention, a grid is interposed between the cover and the acoustic component, said grid being in contact with the tops of the hollow acoustic elements.

[0023] Such a grid limits the risk of damage to the cover by the tops of the hollow acoustic elements while ensuring more uniform pressure of the cover on the acoustic component. In addition, the repeatability of the positioning is improved.

[0024] According to another particular embodiment of the invention, the connecting edges of the acoustic component are made of polyetherimide or polyethersulfone resin.

[0025] Such a resin is suitable for the manufacture of very thin hollow acoustic elements while being able to present excellent transparency.

[0026] According to another particular embodiment of the invention, a plasma treatment is carried out on the acoustic skin and / or on the connecting edges of the acoustic component before fixing.

[0027] Such treatment makes it easier and better to weld the acoustic component to the acoustic skin.

[0028] According to another particular embodiment of the invention, the acoustic skin has a plurality of perforations before being assembled with the acoustic component.

[0029] By making the perforations before assembly, the risk of damaging the hollow acoustic elements when making said perforations is avoided. In addition, these perforations can be used to facilitate the holding in position of the acoustic component against the acoustic skin, for example by allowing air to be sucked inside said elements to generate the vacuum.

[0030] According to another particular embodiment of the invention, the acoustic skin is made of composite material comprising long fibers.

[0031] Thus, the opacity of the acoustic skin is very important and allows easier and faster welding.

[0032] According to another particular embodiment of the invention, the method further comprises the assembly of at least one multicellular body with one or more acoustic components, the assembly between the multicellular body(ies) and the acoustic component(s) being carried out so that the hollow acoustic elements are arranged in the cells of the multicellular body(ies). Brief description of the drawings

[0033] [Fig. 1] Figure 1 is a schematic exploded perspective view of an acoustic panel obtained by the method of the invention.

[0034] [Fig. 2] Figure 2 is a schematic sectional view of the acoustic panel of Figure 1.

[0035] [Fig. 3] Figure 3 is a schematic sectional view illustrating the positioning of the acoustic component against the acoustic skin.

[0036] [Fig. 4] Figure 4 is a schematic sectional view illustrating the holding in position of the acoustic component against the acoustic skin.

[0037] [Fig. 5] Figure 5 is a schematic sectional view illustrating the welding of the acoustic component to the acoustic skin. Description of the embodiments

[0038] Figures 1 and 2 illustrate an example of an acoustic panel 100 comprising in order an acoustic skin 110, an acoustic component 120 comprising a plurality of hollow acoustic elements 121, a multicellular body 130 and a closing skin 140.

[0039] The acoustic skin 110 has the function of allowing the sound waves to be attenuated to pass through inside the acoustic panel 100. For this purpose, the acoustic skin 110 comprises a plurality of perforations 111, as illustrated in FIGS. 1 and 2. Each perforation 111 of the acoustic skin 110 preferably corresponds to a cell of the multicellular body 130 and to a hollow acoustic element 121 of the acoustic component 120. The acoustic skin 110 may have a thickness of between 1 mm and 5 mm, for example 1.5 mm.

[0040] The acoustic skin 110 can be produced in a well-known manner by stamping, by automatic fiber placement known as “AFP” for “Automated Fiber Placement”, or by automatic tape laying known as “ATL” for “Automated Tape Lying”. Other methods can also be used to manufacture the acoustic skin 110, such as manual draping.

[0041] According to the invention, the acoustic skin 110 is made of an opaque thermoplastic material. The opaque thermoplastic material may be a composite material comprising a thermoplastic matrix and fibers or particles. The thermoplastic matrix used may be opaque in itself. The thermoplastic matrix may also be transparent, the opacity being obtained by means of the fibers or particles. Preferably, the opaque thermoplastic material is a composite material comprising a thermoplastic matrix and Long fibers. Long fibers can be continuous or discontinuous. Long discontinuous fibers have a length between 8 and 100 mm. Long continuous fibers have a length greater than 100 mm. Thus, "long fibers" refers to fibers whose length is greater than or equal to 8 mm. The fibers can be made of carbon, glass or aramid. The thermoplastic matrix can be made, for example, of polyaryletherketone (PAEK), polyetherketoneketone (PEKK), polyetherimide (PEI), polyphenylene sulfide (PPS), polyethersulfone (PESU) or polycarbonate (PC).

[0042] The closing skin 140 corresponds to a solid surface intended to reflect the sound waves entering the acoustic panel 100. The closing skin 140 may be a constituent element of the acoustic panel, as in the example described here, or correspond to a structure of an object, for example an aircraft engine. In the latter case, the acoustic panel does not have a closing skin and is directly mounted on the structure of the object.

[0043] The closing skin 140 can be produced in a well-known manner by stamping, by automatic fiber placement called “AFP” for “Automated Fiber Placement”, or by automatic ribbon draping called “ATL” for "Automated Tape Lying". Other methods may also be used to manufacture the closure skin 140. For example, the closure skin may be pre-cured and then glued to the multi-cellular body, or may be formed and cured directly onto the multi-cellular body.

[0044] The closing skin 140 may be made of a composite material comprising fibers, for example a composite material based on carbon fibers impregnated with a thermoplastic or thermosetting resin. The closing skin 140 may not comprise fibers. The closing skin 140 may comprise all the types of fibers and all the types of matrix described previously for the acoustic skin 110. The closing skin 140 may also comprise other types of fibers and other types of matrix than those described previously.

[0045] The multicellular body 130 comprises a plurality of partitions 131 which form a network of ribs, thus delimiting cells 132. The partitions 131 each extend between an upper edge 131a and a lower edge 131b. The upper edges 131a of the partitions 131 define a first assembly face 130a of the multicellular body 130. The lower edges 131b of the partitions 131 define a second assembly face 130b of the multicellular body 130. Thus, the cells 132 extend from the first assembly face 130a to the second assembly face 130b of the multicellular body 130.

[0046] HI Heights 30 cells 132 of the multicellular body 130 are chosen so as to obtain processing of the frequencies of interest according to the use which will be made of the acoustic panel 100.

[0047] In the example illustrated in Figures 1 and 2, the cells 132 of the multicellular body 130 have a square section. It is of course within the scope of the invention if the cells 132 of the multicellular body 130 have a hexagonal, rectangular, round or other section.

[0048] The multicellular body 130 may be made of polymer, composite or metallic material, by additive manufacturing or by conventional means. The multicellular body 130 may also be made in a well-known manner of thermoplastic material by injection, bending or tube assembly. The thermoplastic material may be filled with short fibers or with long fibers. The multicellular body 130 may not be filled.

[0049] The acoustic component 120 comprises a plurality of hollow acoustic elements 121 each having a shape gradually tapering between a base 121a and a top 121b. The hollow acoustic elements 121 are connected to each other by one or more connecting edges 122. The connecting edges 122 comprise an upper face 122a, located on the same plane as the bases 121a of the hollow acoustic elements 121, and a lower face 122b opposite the upper face 122a. The bases 121a of the hollow acoustic elements 121 and the upper faces 122a of the edges 122 define a first assembly face 120a of the acoustic component 120. The first assembly face 120a of the acoustic component 120 is intended to be assembled in contact with the acoustic skin 110. The lower faces 122b of the edges 122 define a second assembly face 120b of the acoustic component 120.The second assembly face 120b of the acoustic component 120 is intended to be assembled to the. contact of the multicellular body 130. More precisely, the second assembly face 120b of the acoustic component 120 is intended to be assembled in contact with the first assembly face 130a of the multicellular body 130.

[0050] In the example shown in Figures 1 and 2, the hollow acoustic elements 121 have a pyramidal shape. However, it does not depart from the scope of the invention if the hollow acoustic elements have, for example, a conical, spiral or funnel shape. In the example shown in Figures 1 and 2, the hollow acoustic elements 121 have symmetry. However, it does not depart from the scope of the invention if the hollow acoustic elements are asymmetrical.

[0051] The hollow acoustic elements 121 may have a wall thickness of between 0.25 mm and 2 mm. Preferably, the hollow acoustic elements 121 have a thickness of less than 1 mm, for example between 0.3 mm and 0.5 mm. Preferably, the base 121a of the hollow acoustic elements 121 is included in a circle whose diameter is between 5 mm and 50 mm. For example, the base 121a of the hollow acoustic elements 121 is included in a circle with a diameter of 20 mm.

[0052] Preferably, the height H120 of the hollow acoustic elements 121 is between 5 mm and 100 mm. For example, the height H120 of the hollow acoustic elements 121 is 20 mm. The height H 120 of the hollow acoustic elements 121 is less than the height Hiso of the cells 132 of the multicellular body 130.

[0053] The acoustic component 120 can be produced in a well-known manner by additive manufacturing, injection or stamping.

[0054] The acoustic component 120 can also be produced in a well-known manner by injection-compression of a thermoplastic material. Injection-compression consists of injecting the material into a half-open mold. Thus, even if the material sets, the channels become less obstructed. When the material is distributed throughout the mold, the mold is completely closed by a closing force to return to the correct dimension. This makes it possible to obtain thinner wall thicknesses for the acoustic components than with a conventional injection process.

[0055] The acoustic component 120 can also be produced in a well-known manner by injection molding with tool temperature control of a thermoplastic material. Injection molding with tool temperature control consists of controlling the temperature of the tool or mold by means of a tool temperature control system, for example with a heat transfer fluid or with air.

[0056] According to the invention, the connecting edges 122 are made of transparent thermoplastic material. The entire acoustic component 120 may be made of transparent thermoplastic material. Only a portion of the acoustic component 120 may be made of transparent thermoplastic material, said portion comprising the connecting edges 122. The hollow acoustic elements 121 may be made of transparent thermoplastic material. Thus, at least the connecting edges 122 of the acoustic component 120 may be made of a transparent resin which can be used for the manufacture of said connecting edges 122 and which allows the welding of said connecting edges 122 to the acoustic skin 110. Thus, preferably, the transparent thermoplastic material may be a polyetherimide (PEI). The transparent thermoplastic material may also be a polycarbonate (PC).Preferably, the transparent thermoplastic material is unfilled, i.e., it does not comprise fibers or particles. Preferably, the transparent thermoplastic material is amorphous, i.e., without a crystalline phase.

[0057] In the example illustrated in Figures 1 and 2, the acoustic panel 100 comprises only a single multicellular body and a single acoustic component. It is of course not outside the scope of the invention if the acoustic panel comprises several superimposed multicellular bodies. It is also not outside the scope of the invention if the acoustic panel comprises several acoustic components. The acoustic panel may also comprise intermediate acoustic skins delimiting different levels of said acoustic panel.

[0058] The assembly of the acoustic component 120 with the acoustic skin 110 comprises a positioning step, a position holding step and a welding step.

[0059] During the positioning step, the acoustic component 120 is placed in contact with the acoustic skin 110, as illustrated in FIG. 3. More precisely, the first assembly face 120a of the acoustic component 120 is placed in contact with the acoustic skin 110, i.e. the upper faces 122a of the edges 122 are placed in contact with the acoustic skin 110.

[0060] Preferably, the acoustic skin 110 already has the perforations 111 before being assembled to the acoustic component 120. In this configuration, the acoustic component 120 is arranged in contact with the acoustic skin 110 so that the perforations 111 open inside the hollow acoustic elements 121 and not on the connecting edges 122. By making the perforations 111 of the acoustic skin 110 before assembly, the risk of the hollow acoustic elements 121 being damaged by a perforation step after assembly is avoided.

[0061] The acoustic component 120 is then held in position in contact with the acoustic skin 110, i.e. the upper faces 122a of the edges 122 are held in position in contact with the acoustic skin 110. This holding in position will continue during the welding step, in order to ensure satisfactory welding. Preferably, the holding in position is achieved by applying pressure such that the upper faces 122a of the edges 122 are pressed against the acoustic skin 110. Welding is thus facilitated.

[0062] When the acoustic panel to be manufactured has restricted dimensions, for example less than 500 mm long and 500 mm wide, the position can be maintained by conventional means, such as for example by a press system or by a clamp. The position can then be maintained mainly on the edges of the acoustic skin 110 and the acoustic component 120.

[0063] When the acoustic panel to be manufactured has large dimensions, for example a length and / or width greater than 500 mm, or a complex three-dimensional shape, holding it in position by conventional means may be insufficient. In this case, according to a particular embodiment of the invention, it is possible, for example, to use rollers configured to apply pressure upstream or downstream of the laser passage. Also in this case, according to another particular embodiment of the invention, the position is maintained by means of a transparent tarpaulin placed under vacuum, as illustrated in Figure 4.

[0064] In this particular embodiment of the invention, a vacuum installation 5 is used, as illustrated in FIG. 4. The acoustic component 120 and the acoustic skin 110 placed in position are arranged in a vacuum chamber 50. The vacuum chamber 50 is delimited at least by a vacuum tank 51. The vacuum tank 51 is arranged opposite the tops 121b of the hollow acoustic elements 121 of the acoustic component 120. Thus, the vacuum tank 51 is opposite the bases 121a of the hollow acoustic elements 121 and the acoustic skin 110.

[0065] Thus, when the chamber 50 is placed under vacuum, the vacuum tank 51 presses, directly or indirectly, on the tops 121b of the hollow acoustic elements 121 of the acoustic component 120 so that the acoustic component 120 is pressed against the acoustic skin 110. The vacuum is created through orifices opening into the vacuum chamber 50.

[0066] The vacuum cover 51 must be made of transparent material to allow laser welding of the upper faces 122a of the edges 122 of the acoustic component 120 with the acoustic skin 110 while maintaining the position.

[0067] The vacuum chamber 50 may also be delimited by a reference surface 52, the acoustic skin 110 resting on the reference surface 52. The reference surface 52 comprises a plurality of orifices 52a arranged in the extension of the perforations 111 of the acoustic skin 110. The air or gases present inside the vacuum chamber 50 can thus be sucked through the orifices 52a of the reference surface 52 and through the perforations 111 of the acoustic skin 110, in order to create the vacuum in the vacuum chamber 50. By sucking the air or gases through the perforations 111 of the acoustic skin 110, it is easier to create a vacuum inside the hollow acoustic elements 121. This allows the acoustic skin 110 to be better held in position by relative to the acoustic component 120. However, it does not go beyond the scope of the invention if the vacuum is created from other orifices.

[0068] The vacuum cover may comprise one or more rigid portions made of transparent material. For example, the vacuum cover may comprise a plate made of transparent material intended to apply pressure to the acoustic component 120, i.e. to the tops 121b of the hollow acoustic elements 121. This plate may for example be made of transparent rigid polymer, for example polycarbonate (PC) or polyetherimide (PEI). The plate may be intended to be in direct contact with the tops 121b of the hollow acoustic elements 121. The use of such a plate integrated into the vacuum cover makes it possible to limit the risk of damage, or even perforation, of said cover by the tops 121b of the hollow acoustic elements 121. Such a plate also makes it possible to improve the repeatability of the position-holding step. The plate preferably has a geometry adapted to that of the acoustic component 120.So the plate is not necessarily flat.

[0069] A grid 53 may also be positioned between the vacuum tank 51 and the tops 121b of the hollow acoustic elements 121, said grid 53 being positioned in contact with the tops 121b of the hollow acoustic elements 121. If the orifices 53a of the grid 53 are not superimposed on the connecting edges 122 of the acoustic component 120, the grid 53 must also be made of transparent material in order to allow laser welding.

[0070] The grid 53 is intended to be in contact with the vacuum tank 51, as illustrated in FIG. 4. The grid 53 is intended to apply pressure to the acoustic component 120, i.e. to the tops 121b of the hollow acoustic elements 121, when the chamber 50 is placed under vacuum. The use of such a grid 53 makes it possible to ensure a homogeneous distribution of the pressure on the tops 121b of the hollow acoustic elements 121 and to improve the repeatability of the position-holding step. Such a grid 53 also makes it possible to limit the risk of damage, or even perforation, of said tank by the tops 121b of the hollow acoustic elements 121.

[0071] When the position is maintained, the laser welding is carried out while maintaining the position, as illustrated in FIG. 5. The laser welding is carried out by emitting a laser beam 60 so that said laser beam 60 passes through a connecting edge 122 of the acoustic component 120 made of transparent material without heating, up to the interface between said connecting edge 122 and the acoustic skin 110 made of opaque material. The laser beam 60 thus passes through the lower face 122b of the connecting edge 122 and then the upper face 122a of the connecting edge 122. If the acoustic skin 110 and the acoustic component 120 are held in position by a tarpaulin 51, the laser beam 60 passes through said tarpaulin 51, the lower face 122b of the connecting edge 122 and then the upper face 122a of the connecting edge 122. Preferably, the laser beam passes through the lower face 122b and the upper face 122a of the connecting edge 122 perpendicular to said surfaces 122a and 122b.

[0072] A laser transmitter 61 can be used. The encounter of the laser beam 60 with the acoustic skin 110 made of opaque material causes a concentration of energy at the interface between the connecting edge 122 and the acoustic skin 110, so as to generate localized heating 6. Such localized heating 6 causes the welding of the connecting edge 122 with the acoustic skin 110. The weld bead thus generated can have a thickness of between 1 and 3 mm. This operation is repeated for each connecting edge 122 to be welded to the acoustic skin 110. After cooling, the acoustic skin 110 and the acoustic component 120 are secured.

[0073] In the present application, infrared welding using an infrared beam is considered to be laser welding using a laser. Laser welding can of course be carried out with a laser whose wavelength corresponds to visible light.

[0074] The acoustic skin 110 and / or the upper face 122a of the connecting edges 122 of the acoustic component 120 may be treated before the welding operation, for example by a plasma treatment to activate the surfaces to be welded.

[0075] The acoustic component 120 is assembled with the multicellular body 130, so that the upper edges 131a of the partitions 131 are fixed in contact with the lower faces 122b of the connecting edges 122 of the acoustic component 120. Thus, the second assembly face 120b of the acoustic component 120 is fixed in contact with the first assembly face 130a of the multicellular body 130. The assembly of the acoustic component 120 to the multicellular body 130 can for example be carried out by welding or by gluing.

[0076] If a closure skin 140 is present, the skin of the closures 140 is assembled with the multicellular body 130, so that the lower edges 131b of the partitions 131 are fixed in contact with the closure skin 140. Thus, the second assembly face 130b of the multicellular body 130 is fixed in contact with the acoustic skin 140. The assembly of the closure skin 140 to the multicellular body 130 can for example be carried out by welding or by gluing. The closure skin 140 can also be formed directly by automatic deposition of fibers on the multicellular body 130, the heating tooling of the deposition head allowing the welding of the deposited strips with the lower edges 131b of the partitions 131.

[0077] The acoustic panel 100 is thus obtained. The acoustic panel 100 can, for example, be used for acoustic attenuation in a nacelle or an aircraft engine, for a blade platform, for an aeronautical sleeve.

[0078] The expression "between ... and ..." must be understood as including the limits.

Claims

Claims

1. A method of manufacturing an acoustic panel (100) comprising assembling at least one acoustic component (120) with an acoustic skin (110), said acoustic component (120) comprising a plurality of hollow acoustic elements (121) having a shape gradually narrowing between a base (121a) and a top (121b), the bases (121a) of the hollow acoustic elements (121) being connected to each other by connecting edges (122), the assembly comprising: - positioning the acoustic skin (110) in contact with the connecting edges (122) of said acoustic component (120), - maintaining the acoustic skin (110) in position against the connecting edges (122), and - fixing the connecting edges (122) of the acoustic component (120) to the acoustic skin (110) while maintaining the position, the method being characterized in that the connecting edges (122) of the acoustic component (120) are made of a transparent thermoplastic material for at least one determined laser wavelength and in that the acoustic skin (110) is made of an opaque thermoplastic material for at least the determined laser wavelength, and in that the fixing of the connecting edges (122) to the acoustic skin (110) comprises the emission of a laser beam (60) having the determined wavelength and passing through the connecting edges (122) until reaching the contact interface between the connecting edges (122) and the acoustic skin (110) so as to cause localized heating at the level of said contact interface resulting in the welding of the connecting edges (122) to the acoustic skin (110),and in that the holding in position of the acoustic skin (110) against the connecting edges (122) of the acoustic component (120) during fixing is carried out by means of a tarpaulin (51) made of transparent material placed under vacuum, the tarpaulin (51) being configured to apply pressure to the tops (121b) of the hollow acoustic elements (121) of the acoustic component (120) so that the connecting edges (122) of the acoustic component (120) are held against the skin, acoustic (110), the laser beam (60) passing through said tarpaulin (51) before passing through the connecting edges (122) during fixing.

2. A method according to claim 1, wherein a grid (53) is interposed between the cover (51) and the acoustic component (120), said grid (53) being in contact with the tops (121b) of the hollow acoustic elements (121).

3. A method according to claim 1 or 2, wherein the connecting edges (122) of the acoustic component (120) are made of polyetherimide or polyethersulfone resin.

4. A method according to any one of claims 1 to 3, wherein a plasma treatment is carried out on the acoustic skin (110) and / or on the connecting edges (122) of the acoustic component (120) before fixing.

5. A method according to any one of claims 1 to 4, wherein the acoustic skin (110) has a plurality of perforations (111) before being assembled with the acoustic component (120).

6. A method according to any one of claims 1 to 5, wherein the acoustic skin (110) is made of a composite material comprising long fibers.

7. A method according to any one of claims 1 to 6, the method further comprising assembling at least one multicellular body (130) with one or more acoustic components (120), the assembly between the at least one multicellular body (130) and the at least one acoustic component (120) being carried out such that the hollow acoustic elements (121) are arranged in the cells (132) of the at least one multicellular body (130).

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