Method for assembling an acoustic panel using a shaping tool

Abstract

The invention relates to a method for manufacturing an acoustic panel (100) comprising at least one multicellular body (130) and an acoustic component (120), the method comprising: - positioning a blank (12) made of thermoplastic material between a male portion (510) and a female portion (520) of a tool (500); - shaping the blank (12) into an acoustic component (120) in a first operation of bringing the male (510) and female (520) portions together so as to close the tool (500), the method being characterised in that it further comprises: - arranging the multicellular body (130) between the female portion (520) of the tool (500) and the acoustic component (120); and then - a second operation of bringing the male (510) and female (520) portions of the tool (500) together so as to press the acoustic component (120) against the multicellular body (130).

Description

Description Title of the invention: Method for assembling an acoustic panel using shaping tools 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 or skin", 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] The various parts of the acoustic panel can be joined together by gluing. However, each gluing operation requires a step in an oven or autoclave to ensure satisfactory fixation. Thus, many costly and time-consuming steps are required to assemble the acoustic panel.

[0007] The assembly of the acoustic component comprising the hollow acoustic elements is particularly delicate. Indeed, since the acoustic component is formed by stamping and then demolding, it must be made of a thermoplastic material whose composition allows easy demolding. However, a thermoplastic material with such properties for demolding has the disadvantage of being difficult to bond.

[0008] The acoustic component can also be assembled by welding. However, there is a significant risk of deforming the hollow acoustic elements due to the heat generated by welding, and such deformation would lead to a deterioration in acoustic performance. This risk of deformation due to heat is higher when the hollow acoustic elements are thin and thin. Statement of the invention

[0009] The present invention aims to remedy the aforementioned drawbacks by proposing a solution for assembling the acoustic panel allowing satisfactory, rapid and inexpensive fixing.

[0010] To this end, the invention proposes a method of manufacturing an acoustic panel comprising at least one multicellular body and an acoustic component comprising a plurality of hollow acoustic elements having a shape gradually narrowing between a base and a top, said method comprising:

[0011] - the positioning of a blank made of thermoplastic material between a male part and a female part of a thermoforming tool,

[0012] - shaping said blank into an acoustic component by first bringing together the male and female parts of the thermoforming tool so as to close said thermoforming tool, the thermoforming tool having a temperature greater than or equal to the glass transition or melting temperature of the thermoplastic material of the blank, then

[0013] - cooling the thermoforming tool to a temperature below the glass transition or melting temperature of the thermoplastic material of the acoustic component, then opening the thermoforming tool,

[0014] the method being characterized in that it further comprises:

[0015] - the arrangement of the multicellular body in the thermoforming tool while the acoustic component remains in contact with the male part of the thermoforming tool, the multicellular body being arranged between the female part of the thermoforming tool and the acoustic component, then

[0016] - a second bringing together of the male and female parts of the thermoforming tool so as to press the acoustic component against the multicellular body so that the hollow acoustic elements of the acoustic component are arranged in the cells of the multicellular body, the male part of the thermoforming tool having a temperature higher than the glass transition or melting temperature of the thermoplastic material(s) of the acoustic component at least at the contact zones between the acoustic component and the multicellular body.

[0017] Thus, by assembling the acoustic component with the multicellular body in the same tooling as that used for the manufacture of said acoustic component, the number of steps required for the manufacture of the acoustic panel is greatly reduced. The risk of deforming the acoustic component during assembly is also reduced.

[0018] In addition, the presence of the multicellular body in the tooling makes it easier to demould the hollow acoustic elements from the acoustic component and reduces the risk of damage or deformation of said elements. acoustics during demolding, by distributing the tensile force more evenly.

[0019] According to a particular embodiment of the invention, the multicellular body is made of thermoplastic material, and in which during the second bringing together of the male and female parts of the thermoforming tool, the male part of said thermoforming tool has a temperature higher than the glass transition or melting temperature of the thermoplastic material(s) of the multicellular body, so that the acoustic component is welded to the multicellular body.

[0020] According to another particular embodiment of the invention, crosslinked glue is placed on the surfaces of the multicellular body intended to be in contact with the acoustic component before the second bringing together of the male and female parts of the thermoforming tool.

[0021] According to another particular embodiment of the invention, the pressure applied by the thermoforming tool is between 5 bars and 20 bars during the second bringing together of the male and female parts of the thermoforming tool.

[0022] Thus, the pressure applied is sufficient to allow satisfactory welding and / or bonding, without however exerting too high a pressure which could deform the multicellular body or the acoustic component.

[0023] According to another particular embodiment of the invention, a metal plate is arranged between the female part of the thermoforming tool and the multicellular body before the second bringing together of the male and female parts of the thermoforming tool.

[0024] Such a plate makes it possible to distribute the forces exerted by the female part of the thermoforming tool on the multicellular body.

[0025] According to another particular embodiment of the invention, during the second bringing together of the male and female parts of the thermoforming tool, the female part of said thermoforming tool has a temperature lower than the glass transition or melting temperature of the or thermoplastic materials of the acoustic component and the multicellular body.

[0026] When the female part is directly in contact with the multicellular body, or separated from the multicellular body only by the metal plate, it is preferable that its temperature remains low to avoid unwanted deformation of the multicellular body.

[0027] According to another particular embodiment of the invention, a closing skin is arranged between the metal plate and the multicellular body before the second bringing together of the male and female parts of the thermoforming tool, so that during the second bringing together of the male and female parts of the thermoforming tool the closing skin is pressed against the multicellular body so as to be assembled to said multicellular body.

[0028] When such a closing skin is arranged between the metal plate and the multicellular body, it is preferable that the temperature of the female part of the tooling is higher than the glass transition or melting temperature of the closing skin, of the thermoplastic material(s) of the acoustic component and of the multicellular body.

[0029] Thus, it may be advantageous to use thermoforming tools with high thermal reactivity, for example thermoforming tools whose temperature is controlled by pulsed air. Indeed, the aim is to enable rapid welding at the interfaces between the acoustic component and the multicellular body and between the multicellular body and the closing skin while limiting the temperature rise at the core of the multicellular structure.

[0030] This allows the acoustic component, the multicellular body and the closing skin, or an intermediate acoustic skin, to be assembled simultaneously.

[0031] According to another particular embodiment of the invention, the closing skin is made of thermoplastic material, and during the second bringing together of the male and female parts of the thermoforming tool, the female part of the thermoforming tool has a temperature higher than the glass transition or melting temperature of the material(s). thermoplastics of the closing skin and the multicellular body, so that the closing skin is welded to the multicellular body.

[0032] A rise in temperature of the female part thus allows the skin to weld to the multicellular body.

[0033] According to another particular embodiment of the invention, the multicellular body assembled at least with the acoustic component is demolded from the thermoforming tool, and an opening acoustic skin is fixed on the face of the acoustic component opposite the multicellular body.

[0034] According to another particular embodiment of the invention, the thermoforming tool is configured so that the spacing distance between the male part and the female part of said thermoforming tool is not less than a given value.

[0035] This reduces the risk of excessive crushing of the multicellular body when the male and female parts are brought together. For example, the thermoforming tool may comprise one or more shims arranged between the female part and the male part, configured to maintain a minimum spacing distance between the female part and the male part. Said shim(s) are arranged so as not to hinder the arrangement of the multicellular body and the acoustic component inside the thermoforming tool. For example, the thermoforming tool may also comprise a control device configured so that the spacing distance between the male part and the female part of said thermoforming tool is not less than a given value.

[0036] According to another particular embodiment of the invention, the male part of the thermoforming tool is arranged below the female part of said thermoforming tool relative to the direction of gravity.

[0037] This configuration allows the multicellular body to be placed in the thermoforming tool directly in contact with the acoustic component which remains in contact with the male part of the tool. This avoids the risk of misalignment between the acoustic component and the multicellular body, which could lead to a damage to parts or blockage of the thermoforming tool during the second approach. Brief description of the drawings

[0038] [Fig. 1] Figure 1 is a schematic exploded perspective view of an acoustic panel obtained by the method of the invention.

[0039] [Fig. 2] Figure 2 is a schematic sectional view of the acoustic panel of Figure 1.

[0040] [Fig. 3] Figure 3 is a schematic sectional view of a thermoforming tool in the open position in which a blank is positioned.

[0041] [Fig. 4] Figure 4 is a schematic sectional view of the thermoforming tool of Figure 3 in the closed position having shaped an acoustic component.

[0042] [Fig. 5] Figure 5 is a schematic sectional view of the thermoforming tool of Figures 3 and 4 in the open position in which the acoustic component is in contact with the male part.

[0043] [Fig. 6] Figure 6 is a schematic sectional view of the thermoforming tool of Figures 3 to 5 in the open position in which a multicellular body is arranged.

[0044] [Fig. 7] Figure 7 is a schematic sectional view of the thermoforming tooling of Figures 3 to 6 in the closed position so as to press the acoustic component against the multicellular body.

[0045] [Fig. 8] Figure 8 is a schematic sectional view of the thermoforming tool of Figures 3 to 5 in the open position in which a multicellular body and a closing skin are arranged according to a variant.

[0046] [Fig. 9] Figure 9 is a schematic sectional view of the thermoforming tool of Figure 8 in the closed position so as to press the acoustic component against the multicellular body and so as to press the closing skin against the multicellular body. Description of the embodiments

[0047] Figures 1 and 2 illustrate an example of an acoustic panel 100 comprising in order an opening acoustic skin 110, an acoustic component 120 comprising a plurality of hollow acoustic elements 121, a multicellular body 130 and a closing skin 140.

[0048] The opening 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 opening 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 opening acoustic skin 110 may have a thickness of between 1 mm and 5 mm, for example 1.5 mm.

[0049] The opening acoustic skin 110 may be made 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 may also be used to manufacture the opening acoustic skin 110, such as manual laying. The opening acoustic skin 110 may be made of thermoplastic material, for example a composite material with a thermoplastic matrix comprising fibers. The fibers may be made of carbon, glass or aramid. The thermoplastic matrix may be made for example of polyaryletherketone (PAEK), polyetherketoneketone (PEKK), polyetherimide (PEI), polyphenylene sulfide (PPS), polyethersulfone (PESU) or polycarbonate (PC).

[0050] 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 100 does not have a closing skin and is directly mounted on the structure of the object.

[0051] The closing skin 140 can be produced in a well-known manner by stamping, by automatic placement of fibers called “AFP” for “Automated Fiber Placement”, or by automatic draping of ribbon called “ATL” for "Automated Tape Lying". Other processes may also be used to manufacture the closure skin 140.

[0052] The closure 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 closure skin 140 may not comprise fibers. The closure skin 140 may comprise all the types of fibers and all the types of matrix described previously for the opening acoustic skin 110. The acoustic skin 140 may also comprise other types of fibers and other types of matrix than those described previously.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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, folding or assembly of tubes. The thermoplastic material may be filled with short fibers or with long fibers. The multicellular body 130 may not be filled.

[0057] 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 in contact with 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.

[0058] 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.

[0059] 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.

[0060] Preferably, the height H 120 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 Hi 30 132 cells of the multicellular body 130.

[0061] 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.

[0062] According to the invention, the acoustic component 120 is produced by stamping.

[0063] Figures 3 to 9 illustrate an example of thermoforming tooling 500 for shaping the acoustic component 120. The thermoforming tooling 500 comprises a male part 510 and a female part 520 arranged opposite one another. The male part 510 and the female part 520 may be made of metal. In the example illustrated in Figure 3, the female part 520 of the thermoforming tooling 500 is fixed relative to the frame of the thermoforming tooling 500 while the male part 510 of the thermoforming tooling 500 is movable in a double direction D relative to the frame. The frame may comprise hold-down clamps 530 for holding the blank 12 of the acoustic component 120 between the male part 510 and the female part 520 of the thermoforming tooling 500.

[0064] The female part 520 of the thermoforming tool 500 comprises molding cavities 521 intended to cooperate with teeth 511 of the male part. 510 of the thermoforming tool 500. The molding cavities 521 and the teeth 511 have a shape corresponding to the shape of the hollow acoustic elements 121 of the acoustic component 120 to be produced.

[0065] The teeth 511 of the male part 510 of the tool 500 are separated from each other by a network of recesses 512. The molding cavities 521 of the female part 520 of the tool 500 are separated from each other by a network of protrusions 522. Thus, the network of recesses 512 of the male part 510 is intended to cooperate with the network of protrusions 522 of the female part 520. The network of recesses 512 of the male part 510 and the network of protrusions 522 of the female part 520 have a shape corresponding to the shape of the connecting edges 122 of the acoustic component 120 to be produced.

[0066] The temperature of the male 510 and female 520 parts is controllable in a well-known manner. The temperature of the male 510 and female 520 parts can be controlled using an induction system, heat transfer fluid channels or a pulsed air system. The thermoforming tool 500 can also include additional heating means for heating the blank 12 even when it is not in contact with the male 510 and female 520 parts.

[0067] As illustrated in Figure 3, a blank 12 made of thermoplastic material is first placed in the thermoforming tool 500 in the open position. The blank 12 is thus placed between the male part 510 and the female part 520. Said blank 12 can be held by means of blank holders 530. The blank 12 is then exposed to a temperature below the glass transition temperature, if it is an amorphous material, or the melting temperature, if it is a semi-crystalline material.

[0068] The blank 12 is then shaped into an acoustic component 120, by increasing the temperature to which the blank 12 is subjected. As illustrated in FIG. 4, a first approach is made between the male part 510 and the female part 520 so as to place the thermoforming tool 500 in the closed position. The male part 510 and the female part 520 are then brought into contact with the blank 12 so as to deform it into an acoustic component 120. When the thermoforming tool 500 is closed, the temperature of the male 510 and female 520 parts of the tool 500 is then greater than or equal to the glass transition temperature, if it is an amorphous material, or the melting temperature, if it is a semi-crystalline material.

[0069] The tool 500 can be held in the closed position and maintained at a temperature greater than or equal to the glass transition temperature, if it is an amorphous material, or melting temperature, if it is a semi-crystalline material, for a determined period.

[0070] Thus, the male 510 and female 520 parts of the tool 500 have a temperature lower than the glass transition or melting temperature of the thermoplastic material when the blank 12 is positioned in said tool 500, then an increase in the temperature of the male 510 and female 520 parts of the tool 500 is carried out until at least the glass transition or melting temperature is reached, the tool 500 being closed for shaping the blank 12 when the glass transition or melting temperature is reached.

[0071] After shaping the acoustic component 120, the tool 500 is cooled to a temperature below the glass transition or melting temperature of the thermoplastic material. Then, the tool 500 is opened by separating the male portion 510 from the female portion 520. When opening the tool 500, the male 510 and female 520 portions are cooled.

[0072] When the tooling 500 is opened, the acoustic component 120 remains in contact with the male part 510 of said tooling 500 due to the differences in thermal expansion and contraction between the male part 510 and the acoustic component 120, as illustrated in FIG. 5. The tooling 500 may also be deliberately configured so that the acoustic component 120 remains in contact with the male part 510 after opening said tooling 500.

[0073] The multicellular body 130 is then placed in the thermoforming tool 500 in the open position, as illustrated in FIG. 6. The multicellular body 130 is thus placed between the male part 510 and the female part 520, and more precisely between the acoustic component 120 and the female part 520.

[0074] The multicellular body 130 is arranged in the thermoforming tool 500 so that the partitions 131 of said multicellular body 130 are positioned in the extension of the network of prominences 522 of the female part 520, as illustrated in FIG. 6. The multicellular body 130 is arranged in the thermoforming tool 500 so that the partitions 131 of the multicellular body 130 are positioned opposite the hollows of the network of hollows 512 of the male part 510.

[0075] In the example illustrated in the figures, the male part is arranged above the female part relative to the direction of gravity. It is of course not outside the scope of the invention if the male part of the thermoforming tool is arranged below the female part of said thermoforming tool relative to the direction of gravity. This configuration is even advantageous insofar as it is thus possible to position the multicellular body in the thermoforming tool directly in contact with the acoustic component remaining in contact with the male part of the tool. This avoids a risk of misalignment between the acoustic component and the multicellular body, which could lead to damage to the parts or to blockage of the thermoforming tool during the second approach.

[0076] According to a particular embodiment, a metal plate (not shown in FIGS. 6 and 7) may also be arranged in the open thermoforming tool 500. Said metal plate is then arranged between the female part 520 of the tool 500 and the multicellular body 130. When the male part is arranged above the female part relative to the direction of gravity, the metal plate is then arranged in the open thermoforming tool 500 so that said metal plate is in contact with the female part 520 of the tool 500 and in contact with the multicellular body 130. When the male part is arranged below the female part relative to the direction of gravity, the metal plate is then arranged in the open thermoforming tool 500 so that said metal plate is in contact with the multicellular body 130.The use of such a plate makes it possible to distribute the closing forces of the tool 500 on the multicellular body 130 in a more homogeneous manner.

[0077] When the multicellular body 130 is suitably arranged in the thermoforming tool, a second approximation is carried out between the male part 510 and the female part 520, so as to place the acoustic component 120 in contact with the multicellular body 130, as illustrated in FIG. 7. The thermoforming tool 500 is then in the semi-closed position. The pressure applied by the thermoforming tool 500 may be between 5 bars and 20 bars when the acoustic component 120 is brought into contact with the multicellular body 130.

[0078] The assembly of the acoustic component 120 with the multicellular component 130 can be carried out by welding. The multicellular body 130 is then made of thermoplastic material. At the time of contact between the multicellular body 130 and the acoustic component 120, the male part 510 of the tool 500 has a temperature higher than the glass transition or melting temperature of the thermoplastic material of the acoustic component 120 and the multicellular body 130 at least at the contact zones between the acoustic component 120 and the multicellular body 130. The male part 510 of the tool 500 can have a temperature higher than the glass transition or melting temperature of the thermoplastic material of the acoustic component 120 and the multicellular body 130 over its entire surface.

[0079] On the other hand, at the time of contacting the multicellular body 130 and the acoustic component 120, the female part 520 of the tool 500 has a temperature lower than the glass transition or melting temperature of the thermoplastic material of the acoustic component 120 and the multicellular body 130. This ensures satisfactory welding of the multicellular body 130 to the acoustic component 120 while limiting the risks of deformation of the multicellular body 130. The holding of the acoustic component 120 against the multicellular body 130 lasts long enough to allow the polymer chains to flow at the interface between the acoustic component 120 and the multicellular body 130. The duration of contact between the acoustic component 120 and the multicellular body 130 is chosen according to the thermoplastic material(s) used. The duration of contact may be between one second and ten minutes.

[0080] The assembly of the acoustic component 120 with the multicellular component 130 can also be carried out by gluing. Crosslinked glue is then arranged on the upper edges 131a of the partitions 131 of the multicellular body 130 before its arrangement in the thermoforming tool 500. At the time of bringing the multicellular body 130 and the acoustic component 120 into contact, the male part 510 of the tool 500 has a temperature higher than the glass transition or melting temperature of the thermoplastic material of the acoustic component 120 and the multicellular body 130. On the other hand, at the time of bringing the multicellular body 130 and the acoustic component 120 into contact, the female part 520 of the tool 500 has a temperature lower than the glass transition or melting temperature of the thermoplastic material of the acoustic component 120 and the multicellular body 130. This ensures satisfactory bonding of the multicellular body 130 to the acoustic component 120 while limiting the risks of deformation of the multicellular body 130.

[0081] The assembly of the acoustic component 120 with the multicellular component 130 can be carried out simultaneously by gluing and by welding. The upper edges 131a of the partitions 131 can be activated by plasma treatment to facilitate welding or gluing before the arrangement of the multicellular body 130 in the thermoforming tool 500.

[0082] The acoustic component 120 and the multicellular body 130 are then demolded to obtain the desired assembly. The opening acoustic skin 110, or an intermediate acoustic skin, is then assembled with the acoustic component 120. The assembly of the opening acoustic skin 110 with the acoustic component 120 can, for example, be carried out by welding or gluing in a well-known manner. The multicellular body 130 is assembled with the closing skin 140, or with an intermediate acoustic skin. The assembly of the closing skin 140 with the multicellular body 130 can, for example, be carried out by welding or gluing in a well-known manner. The acoustic panel 100 is thus obtained.

[0083] According to a variant illustrated in Figures 8 and 9, not only the multicellular body 130 is placed in the open thermoforming tool 500 after the first approach, but also the closing skin 140. Thus, not only is the assembly of the multicellular body 130 with the component acoustic 120 in the thermoforming tool 500, but also the simultaneous assembly of the closing skin 140 with the multicellular body 130.

[0084] As illustrated in Figure 8, a metal plate 540 is placed in the open thermoforming tool 500. Said metal plate 540 is then placed between the female part 520 of the tool 500 and the closing skin 140. When the male part is placed above the female part relative to the direction of gravity, the metal plate 540 is then placed in the open thermoforming tool 500 so that said metal plate 540 is in contact with the female part 520 of the tool 500 and in contact with the closing skin 140. When the male part is placed below the female part relative to the direction of gravity, the metal plate 540 is then placed in the open thermoforming tool 500 so that said metal plate 540 is in contact with the closing skin 140.The use of such a metal plate 540 makes it possible to protect the closing skin 140 from the closing forces of the tool 500 and to prevent it from deforming under the effect of the temperature of the tool 500.

[0085] The closing skin 140 is arranged in the open thermoforming tool 500. Said closing skin 140 is then arranged between the metal plate 540 and the multicellular body 130. The closing skin 140 is then arranged in the open thermoforming tool 500 so that said closing skin 140 is in contact with the metal plate 540 and in contact with the multicellular body 130.

[0086] When the multicellular body 130, the closing skin 140 and the metal plate 540 are suitably arranged in the thermoforming tool 500, a second bringing together of the male part 510 and the female part 520 is carried out, so as to put the acoustic component 120 in contact with the multicellular body 130 and to put the multicellular body 130 in pressed contact with the closing skin 140, as illustrated in FIG. 9. The thermoforming tool 500 is then in the semi-closed position. The pressure applied by the thermoforming tool 500 can be between 5 bars and 20 bars when the acoustic component 120 is put in contact with the multicellular body 130.

[0087] The assembly of the acoustic component 120 with the multicellular component 130 can be carried out by welding. The multicellular body 130 is then made of thermoplastic material. At the time of contacting the multicellular body 130 and the acoustic component 120, the male part 510 of the tool 500 has a temperature higher than the glass transition or melting temperature of the thermoplastic material of the acoustic component 120 and the multicellular body 130. This ensures satisfactory welding of the multicellular body 130 to the acoustic component 120. The holding of the acoustic component 120 against the multicellular body 130 lasts long enough to allow the polymer chains to flow at the interface between the acoustic component 120 and the multicellular body 130.The duration of contact between the acoustic component 120 and the multicellular body 130 is chosen according to the thermoplastic material(s) used. The duration of contact may be between one second and ten minutes.

[0088] The assembly of the acoustic component 120 with the multicellular component 130 can also be carried out by gluing. Crosslinked glue is then placed on the upper edges 131a of the partitions 131 of the multicellular body 130 before it is placed in the thermoforming tool 500. At the time of bringing the multicellular body 130 and the acoustic component 120 into contact, the male part 510 of the tool 500 has a temperature higher than the glass transition or melting temperature of the thermoplastic material of the acoustic component 120 and the multicellular body 130. This ensures satisfactory gluing of the multicellular body 130 to the acoustic component 120.

[0089] The assembly of the acoustic component 120 with the multicellular component 130 can be carried out simultaneously by gluing and by welding. The upper edges 131a of the partitions 131 can be activated by plasma treatment to facilitate welding or gluing before the arrangement of the multicellular body 130 in the thermoforming tool 500.

[0090] The assembly of the closing skin 140 with the multicellular component 130 can be carried out by welding. The multicellular body 130 and the closing skin 140 are then made of thermoplastic material. At the time of the bringing the multicellular body 130 and the acoustic component 120 into contact, the female part 520 of the tool 500 has a temperature higher than the glass transition or melting temperature of the thermoplastic material of the acoustic component 120 and the multicellular body 130. This high temperature of the female part 520 of the tool 500 does not risk disturbing the welding and / or bonding of the acoustic component 120 to the multicellular body 130 because the female part 520 is then separated from the acoustic component 120 by the closure plate 540, by the closure skin 140 and by the multicellular body 130. This ensures satisfactory welding of the multicellular body 130 to the closure skin 140. The pressing of the closure skin 140 against the multicellular body 130 lasts long enough to allow the polymer chains to flow at the interface between the closure skin 140 and the body multicellular 130.The duration of contact between the closing skin 140 and the multicellular body 130 is chosen according to the thermoplastic material(s) used. The duration of contact may be between one second and ten minutes.

[0091] The assembly of the closing skin 140 with the multicellular component 130 can also be carried out by gluing. Crosslinked glue is then placed on the lower edges 131b of the partitions 131 of the multicellular body 130 before it is placed in the thermoforming tool 500. At the time of contact between the multicellular body 130 and the acoustic component 120, the female part 520 of the tool 500 has a temperature higher than the glass transition or melting temperature of the thermoplastic material of the acoustic component 120 and the closing skin 140. This high temperature of the female part 520 of the tool 500 is not likely to disrupt the welding and / or bonding of the acoustic component 120 to the multicellular body 130 because the female part 520 is then separated from the acoustic component 120 by the closing plate 540, by the closing skin 140 and by the multicellular body 130.This ensures satisfactory bonding of the multicellular body 130 to the closing skin 140.

[0092] The assembly of the closure skin 140 with the multicellular component 130 can be carried out simultaneously by gluing and by welding. The lower edges 131b of the partitions 131 can be activated by plasma treatment to facilitate welding or gluing before the arrangement of the multicellular body 130 in the thermoforming tool 500.

[0093] The acoustic component 120, the multicellular body 130 and the closing skin 140 are then demolded to obtain the desired assembly. The closing skin 140 assembled in this embodiment may also be an intermediate acoustic skin. The opening acoustic skin 110, or an intermediate acoustic skin, is then assembled with the acoustic component 120. The opening acoustic skin 110 may, for example, be assembled with the acoustic component 120 by welding or gluing in a well-known manner. The acoustic panel 100 is thus obtained.

[0094] 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.

[0095] The expression "between ... and ..." must be understood as including the limits.

Claims

Claims

1. A method of manufacturing an acoustic panel (100) comprising at least one multicellular body (130) and an acoustic component (120) comprising a plurality of hollow acoustic elements (121) having a shape gradually narrowing between a base (121a) and a top (121b), said method comprising: - positioning a blank (12) made of thermoplastic material between a male part (510) and a female part (520) of a thermoforming tool (500), - shaping said blank (12) into an acoustic component (120) by first bringing together the male (510) and female (520) parts of the thermoforming tool (500) so as to close said thermoforming tool (500), the thermoforming tool (500) having a temperature greater than or equal to the glass transition or melting temperature of the thermoplastic material of the blank (12), then - cooling the thermoforming tool (500) to a temperature below the glass transition or melting temperature of the thermoplastic material of the acoustic component (120), then opening the thermoforming tool (500), the method being characterized in that it further comprises: - arranging the multicellular body (130) in the thermoforming tool (500) while the acoustic component (120) remains in contact with the male part (510) of the thermoforming tool (500), the multicellular body (130) being arranged between the female part (520) of the thermoforming tool (500) and the acoustic component (120), then - a second bringing together of the male (510) and female (520) parts of the thermoforming tool (500) so as to press the acoustic component (120) against the multicellular body (130) so that the hollow acoustic elements (121) of the acoustic component (120) are arranged in the cells (132) of the multicellular body (130), the male part (510) of the thermoforming tool (500) having a temperature higher than the glass transition temperature or melting the thermoplastic material(s) of the acoustic component (120) at least at the contact areas between the acoustic component (120) and the multicellular body (130).

2. Manufacturing method according to claim 1, in which the multicellular body (130) is made of thermoplastic material, and in which during the second bringing together of the male (510) and female (520) parts of the thermoforming tool (500) the male part (510) of said thermoforming tool (500) has a temperature higher than the glass transition or melting temperature of the thermoplastic material(s) of the multicellular body (130), so that the acoustic component (120) is welded to the multicellular body (130).

3. Manufacturing method according to claim 1 or 2, in which crosslinked glue is arranged on the surfaces (131a) of the multicellular body (130) intended to be in contact with the acoustic component (120) before the second bringing together of the male (510) and female (520) parts of the thermoforming tool (500).

4. Manufacturing method according to any one of claims 1 to 3, wherein the pressure applied by the thermoforming tool (500) is between 5 bars and 20 bars during the second bringing together of the male (510) and female (520) parts of the thermoforming tool (500).

5. Manufacturing method according to any one of claims 1 to 4, in which a metal plate (540) is arranged between the female part (520) of the thermoforming tool (500) and the multicellular body (130) before the second bringing together of the male (510) and female (520) parts of the thermoforming tool (500).

6. Manufacturing method according to any one of claims 1 to 5, wherein during the second bringing together of the male (510) and female (520) parts of the thermoforming tool (500) the female part (520) of said thermoforming tool (500) has a temperature lower than the glass transition or melting temperature of the thermoplastic material(s) of the acoustic component (120) and the multicellular body (130).

7. Manufacturing method according to claim 5, wherein a closing skin (140) is arranged between the metal plate (540) and the multicellular body (130) before the second bringing together of the male (510) and female (520) parts of the thermoforming tool (500), so that during the second bringing together of the male (510) and female (520) parts of the thermoforming tool (500) the closing skin (140) is pressed against the multicellular body (130) so as to be assembled to said multicellular body (130).

8. Manufacturing method according to claim 7, in which the closing skin (140) is made of thermoplastic material, and in which during the second bringing together of the male (510) and female (520) parts of the tool (500) the female part (520) of the thermoforming tool (500) has a temperature higher than the glass transition or melting temperature of the thermoplastic material(s) of the closing skin (140) and of the multicellular body (130), so that the closing skin (140) is welded to the multicellular body (130).

9. Manufacturing method according to any one of claims 1 to 8, in which the multicellular body (130) assembled at least with the acoustic component (120) is demolded from the thermoforming tool (500), and in which an acoustic opening skin (110) is fixed on the face of the acoustic component (120) opposite the multicellular body (130).

10. A manufacturing method according to any one of claims 1 to 9, wherein the thermoforming tooling is configured such that the gap distance between the male portion and the female portion of said thermoforming tooling is not less than a given value.

11. A manufacturing method according to any one of claims 1 to 10, wherein the male portion of the thermoforming tool is arranged below the female portion of said thermoforming tool relative to the direction of gravity.

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