Fabrication of a multicellular body from strips of thermoplastic material
The method of arranging and welding thermoplastic strips with conformation blocks addresses the challenge of achieving high material quality and dimensional tolerances in multicellular bodies, resulting in cost-effective production of acoustic attenuation panels.
Patent Information
- Authority / Receiving Office
- FR · FR
- Patent Type
- Applications
- Current Assignee / Owner
- SAFRAN SA
- Filing Date
- 2024-11-14
- Publication Date
- 2026-05-15
AI Technical Summary
Existing manufacturing methods for multicellular bodies in acoustic attenuation panels struggle to achieve sufficient material quality while maintaining thin and consistent partition thicknesses with demanding dimensional tolerances at a reasonable cost.
A method involving the arrangement and welding of thermoplastic strips using conformation blocks to form a multicellular body, where the strips are spaced and shaped into rows, and then fused to create partitions with controlled geometric tolerances, using temperature control and compression elements to ensure material quality and cost-effectiveness.
The method achieves excellent material quality and controlled geometric tolerances in thin-walled multicellular bodies, ensuring consistent partition thicknesses and reduced production costs.
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Abstract
Description
Title of the invention: Fabrication of a multicellular body from thermoplastic strips. Technical field
[0001] The present invention relates to the manufacture of multicellular bodies, for example the manufacture of multicellular bodies for acoustic attenuation panels. Prior art
[0002] Acoustic attenuation panels typically consist of a plate or skin with an acoustic surface permeable to the acoustic waves to be attenuated and a solid reflective plate or skin, referred to as the "closing plate or skin," with at least one multicellular body disposed between these two skins. The multicellular body is generally made up of a set of partitions forming a rib network and delimiting a plurality of cells. As is well known, such panels form Helmholtz-type resonators that attenuate acoustic waves within a certain frequency range.
[0003] It is also well known to place hollow acoustic elements, for example open truncated cones, within the cells of the multicellular body. These hollow acoustic elements make it possible to process low frequencies without resorting to an excessively thick multicellular body. Such acoustic attenuation panels are described, for example, in documents WO 2023089267 A1, WO 2023079233 A1 and WO 2023135381 A1
[0004] The multicellular body is conventionally produced by injection molding, stamping, extrusion, or additive manufacturing. However, such manufacturing methods do not always allow for achieving sufficient material quality while maintaining thin and consistent partition thicknesses that meet demanding dimensional tolerances, at a reasonable cost. Description of the invention
[0005] The present invention aims to propose a method for manufacturing a multicellular body, with or without hollow protruding elements, remedying the aforementioned disadvantages.
[0006] To this end, the invention proposes a method for manufacturing a multicellular body comprising:
[0007] - the arrangement of at least the first, second and third strips in material thermoplastic, said first, second and third strips of thermoplastic material being kept spaced apart from each other so as to delimit between the first and second strips of thermoplastic material a first row and between the second and third strips of thermoplastic material a second row, the first row comprising at least first and second conformation blocks spaced apart, the second row comprising at least a third conformation block, then
[0008] - the displacement of at least the third conformation block in the present space between at least the first and second conformation blocks so as to form a third row by the fusion of the first and second rows, the second band of thermoplastic material being shaped into notches by said first, second and third conformation blocks, the first and third bands of thermoplastic material extending on either side of the third row obtained, and
[0009] - the approach of at least the first and second conformational blocks towards the at least the third conformational block, then
[0010] - the welding of said at least first, second and third strips of material thermoplastics bonded to each other to obtain a multicellular body.
[0011] According to a first embodiment, the invention proposes a method for manufacturing a multicellular body comprising:
[0012] - the arrangement along a first direction of at least the first, second and third bands of thermoplastic material, said first, second and third bands of thermoplastic material being kept spaced apart from each other along a second direction perpendicular to the first direction so as to delimit between the first and second bands of thermoplastic material a first row and between the second and third bands of thermoplastic material a second row, the first row comprising at least first and second conformation blocks spaced apart from each other along the first direction, the second row comprising at least one third conformation block, then
[0013] - the displacement of at least the third conformation block following the second direction in the space present between the at least first and second conformation blocks so as to form a third row by the fusion of the first and second rows, the second band of thermoplastic material being shaped into crenellations by said first, second and third conformation blocks, the first and third bands of thermoplastic material extending in the first direction, and
[0014] - the approach along the first direction of at least the first and second conformation blocks towards at least the third conformation block, then
[0015] - the welding of said at least first, second and third strips of material thermoplastics bonded to each other to obtain a multicellular body.
[0016] According to a second embodiment, wherein the arrangement of at least the first, second and third thermoplastic material strips is carried out such that said thermoplastic material strips are arranged along the radii of a principal circle, the first row being present in a first sector of the principal circle defined between the first and second thermoplastic material strips and the second row being present in a second sector of the principal circle defined between the second and third thermoplastic material strips, the first, second and third conformation blocks being respectively present on a first, second and third concentric circles of the principal circle, the first circle having a smaller radius than the radii of the second and third circles, the second circle having a larger radius than the third circle,in which the displacement of at least the third conformation block is carried out along an arc of a circle belonging to the third circle such that the first, second, and third conformation blocks are aligned.
[0017] Thus, the geometric tolerances of the resulting multicellular body are controlled even in the case of thin walls, at a reduced cost. The material quality is also excellent.
[0018] According to a particular embodiment of the invention, the conforming blocks are arranged in a staggered pattern when arranging the thermoplastic material strips.
[0019] According to another particular embodiment of the invention, the welding is carried out by heating the thermoplastic strips to a temperature above the melting point of the thermoplastic material if it is amorphous, or above the glass transition temperature of the thermoplastic material otherwise. In particular, the welding is carried out by heating the thermoplastic strips to a temperature above the glass transition temperature of the thermoplastic material if said thermoplastic material is semi-crystalline.
[0020] According to another particular embodiment of the invention, the conformation blocks have a temperature greater than 100°C when the thermoplastic material strips are arranged.
[0021] In particular, when arranging the strips of thermoplastic material, the conforming blocks may have a temperature between 50% and 70% of the melting temperature of the thermoplastic material if said thermoplastic material is amorphous, between 50% and 70% of the glass transition temperature of the thermoplastic material otherwise, for example if said thermoplastic material is semi-crystalline.
[0022] Thus, the temperature of the blocks is not too high to avoid prematurely melting the strips, but sufficient to optimize the cycle time of the process. Indeed, the conforming blocks can reach the temperature sufficient to allow the welding of the strips more quickly.
[0023] According to another particular embodiment of the invention, positioning elements hold the ends of the thermoplastic material strips.
[0024] Thus, the shaping of the thermoplastic material strips is simplified.
[0025] According to another particular embodiment of the invention, the element(s) holding in position the second band of thermoplastic material exerts a tension on said second band of thermoplastic material during the movement of the third conforming block.
[0026] Thus, the thermoplastic material strip(s) intended to be shaped into crenellations are put under tension so as to avoid the formation of folds during their shaping.
[0027] According to another particular embodiment of the invention, first compression elements allow the conformation blocks to be compressed along a direction perpendicular to the direction of the third row obtained and second compression elements allow the conformation blocks to be compressed along a direction corresponding to the direction of the third row obtained.
[0028] According to another particular aspect of the first variant, first compression elements allow the conformation blocks to be compressed along the second direction and second compression elements allow the conformation blocks to be compressed along the first direction.
[0029] Thus, the geometric tolerances for the thickness of the partitions of the multicellular body are easier to control. The compression elements also help to partially ensure the sealing of the mold containing the thermoplastic strips, in particular to prevent the thermoplastic material from leaking outside the mold.
[0030] According to another particular embodiment of the invention, the first compression elements comprise cutting means configured to cut the strips of thermoplastic material before welding.
[0031] Thus, it is possible to cut out the portions of the thermoplastic material strips that protrude from the forming blocks.
[0032] According to a second embodiment of the invention, the conformation blocks comprise an open cavity opening onto one of the surfaces of the conformation blocks, a matrix comprising a plurality of teeth being arranged opposite the conformation blocks, the teeth of the matrix being configured to cooperate with the open cavities of the conformation blocks, the method comprising the interposition of a thermoplastic film extending in the first and second directions between the conforming blocks and the die and then stamping said thermoplastic film by making the teeth of the die cooperate with the open cavities of the conforming blocks so as to form hollow protruding elements having a shape extending progressively between a base and a top, the process further comprising welding the thermoplastic film to the thermoplastic strips.
[0033] The invention also relates to a method of manufacturing an acoustic attenuation panel comprising the production of a multicellular body according to the method described above, and the assembly of the multicellular body with at least one acoustic skin. Brief description of the drawings
[0034] [Fig-1] Fig. 1 is a schematic perspective view of a plurality of strips arranged in a mold in installation position according to a first embodiment of the invention and according to a first installation variant.
[0035] [Fig.2] The [Fig.2] is a schematic top view of the bands of the [Fig.1] arranged in the mold during the approach of the conformation blocks along the second direction.
[0036] [Fig.3] The [Fig.3] is a schematic top view of the strips of figures 1 and 2 arranged in the mold in welding position.
[0037] [Fig.4] The [Fig.4] is a schematic perspective view of a multicellular body obtained according to the first embodiment of the invention.
[0038] [Fig.5] The [Fig.5] is a schematic exploded perspective view of strips arranged in a mold in welding position according to a second embodiment of the invention.
[0039] [Fig.6] The [Fig.6] is a schematic cross-sectional view of an acoustic attenuation panel comprising a multicellular body obtained according to the second embodiment of the invention.
[0040] [Fig. 7] [Fig. 7] is a schematic top view of a plurality of strips arranged in a mold in the installation position according to a second embodiment. Description of embodiments
[0041] Figures 1 to 5 illustrate two examples of a method for manufacturing a multicellular body according to a first embodiment of the invention. In this first embodiment of the invention, the multicellular body is devoid of hollow protruding elements. Thus, the multicellular body is formed solely by a network of partitions.
[0042] The process includes supplying a plurality of 100 strips of thermoplastic material.
[0043] The strips 100 can be obtained by cutting a film of thermoplastic material. The strips 100 can have a thickness of less than 0.5 mm, or even less than 0.3 mm. In particular, the strips 100 can have a thickness between 0.1 mm and 0.3 mm. The strips 100 can have a width between 20 mm and 50 mm, for example between 30 mm and 40 mm.
[0044] The strips 100 extend lengthwise between a first end 101 and a second end 102. The strips 100 extend widthwise between a first slice 103 and a second slice 104. The strips 100 extend thicknesswise between a first face and a second face.
[0045] The thermoplastic material used for the strips 100 may be selected, in particular but not exclusively, from the following materials: polyaryletherketones (PAEKs) such as polyetheretherketone (PEEK) and polyetherketoneketone (PEKK), polyetherimides (PEIs), polycarbonate (PC), polyphenylene sulfide (PPS), polyethersulfone (PESU), polyphenylsulfone (PPSU), and polysulfones (PSUs). The thermoplastic material may be filled with particles and / or fibers, or be unfilled with particles and / or fibers.
[0046] The process also includes the provision of a mold 5.
[0047] The mold 5 comprises a plurality of conformation blocks 55. The blocks of Conformation 55 blocks are arranged in rows and columns. Mold 5 comprises a plurality of rows 1a, 1b, 2a, 2b, 3a, 3b of conformation 55 blocks. The rows 1a, 1b, 2a, 2b, 3a, 3b of conformation 55 blocks extend along a first direction Db. The columns of conformation 55 blocks extend along a second direction D2. The second direction D2 is perpendicular to the first direction Dh.
[0048] The conformation blocks 55 have a first dimension along the first direction Di and a second dimension along the second direction D2. The conformation blocks 55 have a height along a third direction D3 perpendicular to the first and second directions Di and D2. The conformation blocks 55 preferably all have the same dimensions.
[0049] The conformation blocks 55 may have a square cross-section. The conformation blocks may also have a cross-section of another shape, for example, a triangular or hexagonal cross-section. The first dimension of the conformation blocks 55 is then, on average, equal to the second dimension of the blocks 55. The conformation blocks 55 may also have a rectangular cross-section. not square. The blocks of conformation 55 preferably all have the same shape.
[0050] The conformation blocks 55 are mobile between an installation position and a welding position.
[0051] Figure 1 illustrates the mold 5 in its installation position, that is, the mold 5 when the forming blocks 55 are in their installation position. The installation position corresponds to the position of the mold 5 or the forming blocks 55 when the strips 100 are arranged. In the example shown in Figure 1, the mold 5 is in an installation position according to a first variant. The present invention is, of course, not limited to this installation position. A second variant of the installation position is described later in this description.
[0052] In the installation position, the mold 5 comprises at least a first row la of conformation blocks 55 and at least a second row 1b of conformation blocks 55. The first row la is adjacent to the second row 1b of conformation blocks 55.
[0053] The first row 1 includes at least a first conformation block and a second conformation block spaced from each other along the first direction Dp. The second row 1b includes at least a third conformation block.
[0054] Preferably, as illustrated in [Fig. 1], the mold 5 comprises a plurality of first rows la, 2a, 3a and a plurality of second rows 1b, 2b, 3b. Each first row la, 2a, 3a is associated with a second row 1b, 2b, 3b. The mold 5 may comprise a regular alternation of first rows la, 2a, 3a and second rows 1b, 2b, 3b. Thus, in the installation position, the mold 5 comprises a plurality of row pairs, each row pair comprising a first row la, 2a, 3a and a second row 1b, 2b, 3b. Thus, in the installation position, the mold 5 preferably has an even number of rows of conformation blocks 55.
[0055] In the installation position, each first row la, 2a, 3a comprises at least two conformation blocks spaced apart along the first direction Dp. Each second row 1b, 2b, 3b comprises at least one conformation block.
[0056] More generally, each first row la, 2a, 3a comprises a plurality of conformation blocks 55 spaced from each other along the first direction Db More particularly, each first row la, 2a, 3a comprises a plurality of conformation blocks 55 spaced from each other along the first direction Di by a space greater than the first dimension of the conformation blocks 55.
[0057] Similarly, each second row 1b, 2b, 3b can comprise a plurality of conformation blocks 55 spaced from each other along the first direction Db More specifically, each second row 1b, 2b, 3b can comprise a plurality of conformation blocks 55 spaced apart from each other along the first direction Di by a space greater than the first dimension of the conformation blocks 55.
[0058] In the installation position, the conformation blocks 55 are arranged in a staggered pattern. The conformation blocks 55 of the first rows 1a, 2a, 3a are offset relative to the conformation blocks 55 of the second rows 1b, 2b, 3b in the installation position. Thus, each conformation block 55 of one of the first rows 1a, 2a, 3a is adjacent to a space in the second row 1b, 2b, 3b belonging to the same pair of rows. In particular, each conformation block 55 of a row can be adjacent to a space in the adjacent row(s).
[0059] Similarly, the conformation blocks 55 in the same column are offset from the conformation blocks 55 in the adjacent column(s). In particular, each column of conformation blocks 55 comprises only conformation blocks 55 belonging to the first rows 1a, 2a, 3a or comprises only conformation blocks 55 belonging to the second rows 1b, 2b, 3b.
[0060] The method comprises arranging the strips 100 in the mold 5 while the forming blocks 55 are in the installation position. The strips 100 are arranged in the mold 5 parallel to each other. The strips 100 are arranged in the mold 5 such that the strips 100 extend lengthwise along the first direction Dp. The strips 100 are arranged in the mold 5 spaced apart along the second direction D2. The strips 100 are arranged in the mold 5 such that the strips 100 extend widthwise along the third direction D3. The strips 100 are arranged in the mold 5 such that the strips 100 extend thicknesswise along the second direction D2. The strips 100 are interposed between the rows of forming blocks 55. Only one strip is interposed between two rows of forming blocks 55.Each row of conformation blocks 55 is framed on both sides along the second direction D2 by one of the strips 100. Except for the strips 100 present at the ends of the mold 5 along the second direction D2, the first face of each strip 100 is positioned opposite a row of blocks 55 and the second face of each strip 100 is positioned opposite a row of blocks 55. Thus, at least the first or second face of each strip 100 is positioned opposite a row of blocks 55. Conventionally, if the mold 5 comprises n rows of blocks 55 in the installation position, n+1 strips 100 are placed in the mold 5.
[0061] The strips 100 arranged in the mold 5 are held in position by positioning elements 51 and 52. The positioning elements 51 and 52 are in contact with the ends 101 and 102 of the strips 100. Thus, each strip 100 is held in position at its first end 101 by one of the positioning elements 51, 52 and held in position at its second end 102 by one of the positioning elements 51, 52. At least part of the positioning elements 51 is fixed along the first direction Db. Part of the positioning elements 52 may be movable along the first direction Di to allow tensioning of the strip 100 that they hold in position, in order to prevent the creation of unwanted creases. Preferably, each strip 100 is held by at least one fixed positioning element 51. Thus, each strip 100 is held by two fixed positioning elements 51 at each end 101, 102, or by one fixed positioning element 51 at one end 101, 102 and by a movable positioning element 52 at the other end 101, 102.
[0062] The mold 5 can be preheated before the strips 100 are placed in it. Thus, when the strips 100 are placed in the mold 5, the mold 5 is at a temperature above ambient temperature. In particular, the strips 100 can be placed in the mold 5 when the mold 5 is at a temperature above 100°C. The strips 100 can be placed in the mold 5 when the mold 5 is at a temperature between 50% and 70% of the melting temperature of the thermoplastic material if said thermoplastic material is amorphous, or between 50% and 70% of the glass transition temperature of the thermoplastic material otherwise, for example, if said thermoplastic material is semi-crystalline.
[0063] The process then includes moving the shaping blocks 55 from their installation position to their welding position, as illustrated in Figures 2 and 3.
[0064] The movement of the shaping blocks 55 from their installation position to their welding position includes the movement of the shaping blocks 55 along the second direction D2 and the movement of the shaping blocks 55 along the first direction Di.
[0065] The mold 5 may include a system of slides allowing the movement of the conformation blocks 55. Other systems may of course be used to move the conformation blocks 55.
[0066] The movement of the conformation blocks 55 along the first direction Di preferably begins after the movement of the conformation blocks 55 along the second direction D2 has begun. The movement of the conformation blocks 55 along the first direction Di may begin after the movement of the conformation blocks 55 along the second direction D2 has ended. The movement of the conformation blocks 55 along the first direction Di may begin after the beginning of the The movement of conformation blocks 55 along the second direction D2 occurs before the end of the movement of conformation blocks 55 along the second direction D2. The movement of conformation blocks 55 along the first direction Di ends after the movement of conformation blocks 55 along the second direction D2.
[0067] The displacement of the conformation blocks 55 along the second direction D2 includes the displacement of at least one of the blocks of one of the first rows 1a, 2a, 3a along the second direction D2 in the space present between two conformation blocks 55 of the corresponding second row 1b, 2b, 3b.
[0068] The conformation blocks 55 move along the second direction D2 so as to merge the rows la, 1b, 2a, 2b, 3a, 3b of conformation blocks 55 in pairs. In particular, each first row la, 2a, 3a of conformation blocks 55 merges with one of the second rows 1b, 2b, 3b of conformation blocks 55. The conformation blocks 55 of the second rows 1b, 2b, 3b are inserted between the conformation blocks 55 of the first rows la, 2a, 3a. Thus, the conformation blocks 55 of the second rows 1b, 2b, 3b occupy the spaces between the conformation blocks 55 of the first rows la, 2a, 3a.
[0069] The first rows la, 2a, 3a and the second rows 1b, 2b, 3b merge to form third rows 1, 2, 3. Thus, each pair of rows forms a single third row 1, 2, 3. In the welding position, the mold 5 has no first rows la, 2a, 3a and no second rows 1b, 2b, 3b. Each third row 1, 2, 3 is formed by a regular alternation of conformation blocks 55 that belonged to one of the first rows la, 2a, 3a and conformation blocks 55 that belonged to one of the second rows 1b, 2b, 3b.
[0070] The band or bands 100 present between two rows of fused conformation blocks 55 are shaped into crenellations by the conformation blocks 55. This gives crenellated bands 120.
[0071] The crenellated bands 120 comprise an alternation of one or more portions extending along the first direction Di and one or more portions extending along the second direction D2.
[0072] The crenellated bands 120 are preferably held by at least one movable retaining element 52 along the first direction in order to facilitate the shaping of the crenellations without creases.
[0073] The band(s) 100 present between the pairs of rows remain straight. The band(s) 100 present between the pairs of rows are not shaped by the conformation blocks 55. Straight bands 110 are thus preserved. The straight bands 110 extend only along the first direction Dh
[0074] This gives a regular alternation of crenellated bands 120 and straight bands 110. Each crenellated band 120 is framed by two straight bands 110 along the second direction D2.
[0075] The straight strips 110 are preferably held only by fixed retaining elements 51 along the first direction Di. The straight strips 110 are not held by movable retaining elements 52 along the first direction Db.
[0076] The movement of the conformation blocks 55 along the second direction D2 can be accompanied by the movement of the positioning elements 51, 52 along the second direction D2. Thus, the straight strips 110 and the crenellated strips 120 are not deformed at their ends 101, 102.
[0077] Displacing the conformation blocks 55 along the second direction D2 also allows the bands 100 to be compressed between the conformation blocks 55 along the second direction D2. Thus, the crenellated bands 120 and the straight bands 110 are compressed along the second direction D2 between the conformation blocks 55. In particular, the portions of the crenellated bands 120 extending along the first direction Di are compressed along the second direction D2 between the conformation blocks 55.
[0078] As illustrated in [Fig. 3], the mold 5 may include first compression elements 53. The first compression elements 53 apply pressure along the second direction D2 on the forming blocks 55. The first compression elements 53 are arranged on either side of the forming blocks 55 along the second direction D2. Each first compression element 53 comes into contact with one of the strips 100 in the welding position. In particular, each first compression element 53 may come into contact with a straight strip 110 in the welding position. The first compression elements 53 may allow the mold 5 to be closed along the second direction D2. The first compression elements 53 may apply the pressure along the second direction D2 by means of one or more cylinders, or by means of a press.
[0079] Displacing the conformation blocks 55 along the first direction Di allows the bands 100 to be compressed between the conformation blocks 55 along the second direction D2. Thus, the crenellated bands 120 are compressed along the first direction Di between the conformation blocks 55. In particular, the portions of the crenellated bands 120 extending along the second direction D2 are compressed along the first direction Di between the conformation blocks 55.
[0080] As illustrated in [Fig. 3], the mold 5 may include second compression elements 54. The second compression elements 54 apply pressure along the first direction Di on the forming blocks 55. The second compression elements 54 are arranged on either side of the forming blocks 55 along the first direction Di. Each second compression element 54 comes into contact with one of the forming blocks 55 in the welding position. Preferably, each third row 1, 2, 3 of forming blocks 55 is framed by two second compression elements 54 along the first direction Di in the welding position. The second compression elements 54 are arranged between the strips 100 along the second direction D2.The second compression elements 54 can allow the mold 5 to be closed along the first direction Db. The second compression elements 54 can apply pressure along the first direction Di by means of one or more cylinders, or by means of a press.
[0081] According to a particular aspect of the invention, the second compression elements 54 may include cutting means (not shown). The cutting means are configured to cut the strips 100. In particular, the cutting means are configured to cut the portions of the strips 100 that are not in contact with the forming blocks 55. The cutting means are configured to cut the portions of the strips 100 that are located outside the closed mold 5.
[0082] The first compression elements 53 can be configured to produce a seal to the thermoplastic material along the second direction D2 during the manufacturing process of the multicellular body. The second compression elements 5 can be configured to produce a seal to the thermoplastic material along the first direction Di during the manufacturing process of the multicellular body.
[0083] In the welding position, the mold 5 can also be closed along the third direction D3 by a top plate (not shown). The top plate extends along the first direction Di and along the second direction D2. The top plate is perpendicular to the third direction D3. The top plate can come into contact with the first and / or second compression elements 53, 54. The top plate covers the forming blocks 55. The top plate can come into contact with the second slices 104 of the strips 100.
[0084] When the mold 5 is closed in the welding position, the crenellated strips 120 and the straight strips 110 are welded to each other. The welding of the crenellated strips 120 and the straight strips 110 can be carried out by Several methods are possible. Preferably, welding is carried out by heating the slotted strips 120 and the straight strips 110 to a temperature above the melting point of the thermoplastic material if it is amorphous, or above the glass transition temperature of the thermoplastic material otherwise. The strips can also be heated by bringing the mold 5 to a temperature above the melting point of the thermoplastic material if it is amorphous, or above the glass transition temperature of the thermoplastic material otherwise. Welding can also be localized to the contact areas between the strips.
[0085] When the welding of the crenellated strips 120 and the straight strips 110 is carried out, a multicellular body 200 is obtained.
[0086] After cooling the multicellular body to a temperature less than or equal to the glass transition temperature of the thermoplastic material, it can be removed from the mold 5.
[0087] A multicellular body 200 is thus obtained, as illustrated in [Fig. 4]. The multicellular body 200 is formed by a plurality of septa 210. The septa 210 form a network of ribs. The septa 210 form a grid. The septa 210 delimit cells. The cells have a rectangular cross-section, for example, a square cross-section. The cells can also have other shapes, depending on the shape of the cross-section of the conformation blocks 55 used. Thus, the cells can, for example, also have a triangular or hexagonal shape.
[0088] The partitions 210 are formed by the strips 100 welded together. The partitions 210 extend vertically along the third direction D3. The partitions 210 extending along the first direction Di are formed by the straight strips 110 and by certain portions of the crenellated strips 120. The partitions 210 extending along the second direction D2 are formed by certain portions of the crenellated strips 120. The partitions 210 extending along the second direction D2 lack portions of the straight strips 110.
[0089] The partitions 210 extend vertically between an upper edge 214 and a lower edge 213. The lower edges 213 of the partitions 210 correspond to the first sections 103 of the strips 100. The upper edges 214 of the partitions 210 correspond to the second sections 104 of the strips 100. The upper edges 214 of the partitions 210 are intended to be in contact with an acoustic skin or an acoustic component comprising a plurality of hollow acoustic elements having a shape that gradually narrows between a base and an apex. The lower edges 213 of the partitions 210 are intended to be in contact with an acoustic skin, a closing skin, or a wall.
[0090] Figures 5 and 6 illustrate an example of a method for manufacturing a multicellular body according to a second embodiment of the invention. In this second embodiment of the invention, the multicellular body comprises hollow protruding elements present in the cells of said multicellular body, said hollow protruding elements having a shape that gradually reduces between a base and an apex.
[0091] The mold 6 used in the second embodiment of the invention comprises conformation blocks 56 having the characteristics of the conformation blocks 55 described in the first embodiment of the invention. The conformation blocks 56 of the second embodiment of the invention further comprise each an open cavity 56a. The open cavities 56a extend along the third direction D3. The open cavities 56a open onto a surface of the conformation blocks 56 perpendicular to the third direction D3.
[0092] The mold 6 used in the second embodiment of the invention may also include positioning elements 51, 52 as described above. The mold 6 used in the second embodiment of the invention may also include compression elements 53, 54 as described above. The mold 6 used in the second embodiment of the invention does not include a top plate as described in the first embodiment of the invention.
[0093] The mold 6 used in the second embodiment of the invention comprises a die 60 arranged opposite the open cavities 56a of the conformation blocks 56. The die 60 comprises a plurality of teeth 60a arranged opposite the open cavities 56a of the conformation blocks 56. The teeth 60a of the die 60 are configured to cooperate with the open cavities 56a of the conformation blocks 56. The teeth 60a form protruding elements of the die 60.
[0094] In this second embodiment of the invention, the strips 100 are arranged in the mold 6 comprising the conformation blocks 56 as described in the first embodiment of the invention.
[0095] Similarly, the conformation blocks 56 are moved as described in the first embodiment of the invention to reach a welding position.
[0096] Unlike the first embodiment of the invention, in the second embodiment of the invention, the mold 6 is not closed by a top plate.
[0097] When the conformation blocks 56 are in the welding position, a thermoplastic film 130 is interposed between the conformation blocks 56 and the die 60. Then, the die 60 is compressed against the conformation blocks 56 so that the teeth 60a of the die 60 cooperate with the open cavities 56a of the conformation blocks 56. The compression of the die 60 against the conformation blocks 56 allows the thermoplastic film 130 to be shaped so as to obtain hollow protruding elements 330 inside the cells of the multicellular body 130. The compression of the matrix 60 against the conformation blocks 56 allows the mold 6 to be closed.
[0098] The thermoplastic material used for the film 130 may be selected, in particular but not exclusively, from the following materials: polyaryletherketones (PAEKs) such as polyetheretherketone (PEEK) and polyetherketoneketone (PEKK), polyetherimides (PEIs), polycarbonate (PC), polyphenylene sulfide (PPS), polyethersulfone (PESU), polyphenylsulfone (PPSU), and polysulfones (PSUs). The thermoplastic material may be filled with particles and / or fibers, or be unfilled with particles and / or fibers.
[0099] The thermoplastic film 130 can be made of the same material as the strips 100. This makes it easier to ensure a good quality weld between the film 130 and the strips 100. However, the thermoplastic film 130 can be made of a different material than the strips 100.
[0100] According to a particular aspect of the invention, the teeth 60a of the die 60 can create perforations in the thermoplastic film 130. This aspect is particularly useful when the resulting hollow protruding elements 330 are configured to perform an acoustic function.
[0101] Similar to the first embodiment of the invention, the mold 6 can be preheated before the strips 100 and the film 130 are placed in it. Thus, when the strips 100 and the film 130 are placed in the mold 6, the mold 6 is at a temperature above ambient temperature. In particular, the strips 100 and the film 130 can be placed in the mold 6 when the mold 6 is at a temperature above 100°C. The strips 100 and the film 130 can be placed in the mold 6 when the mold 6 is at a temperature between 50% and 70% of the melting temperature of the thermoplastic material if said thermoplastic material is amorphous, or between 50% and 70% of the glass transition temperature of the thermoplastic material otherwise, for example, if said thermoplastic material is semi-crystalline.
[0102] The thermoplastic film 130 is welded to the crenellated strips 120 and the straight strips 110. Preferably, the welding of the strips 100 together and the welding of the film 130 to the strips 100 are carried out simultaneously.
[0103] When the mold 6 is closed in the welding position, the crenellated strips 120 and the straight strips 110 are welded to each other, and the film 130 is welded to the crenellated strips 120 and the straight strips 110. The welding of the crenellated strips 120 to the straight strips 110 can be carried out in several ways. The welding of the crenellated strips 120 and The joining of straight strips 110 with film 130 can be carried out in several ways. Preferably, the welding is performed by heating the slotted strips 120, the straight strips 110, and the film 130 to a temperature above the melting point of the thermoplastic material if it is amorphous, or above the glass transition temperature of the thermoplastic material otherwise. If the film material 130 and the strip material 100 have different glass transition and / or melting points, each is heated to a temperature above its respective glass transition and / or melting point. The heating of the strips can be carried out by heating the mold 5 to a temperature above the melting point of the thermoplastic material if it is amorphous, or above the glass transition temperature of the thermoplastic material otherwise. The welding can also be localized to the contact areas between the strips, or between the strips and the film..
[0104] When the welding of the crenellated strips 120, the straight strips 110 and the film 130 is carried out, a multicellular body 300 is obtained.
[0105] After cooling the multicellular body to a temperature less than or equal to the glass transition temperature of the thermoplastic material, it can be removed from the mold 6.
[0106] A multicellular body 300 is thus obtained as illustrated in [Fig. 6]. The multicellular body 300 comprises a plurality of septa 310. The septa 310 form a network of ribs. The septa 310 form a grid. The septa 310 delimit cells. The cells have a rectangular cross-section, for example, a square cross-section. The septa 310 are formed by the strips 100 fused to one another. The septa 310 extend vertically along the third direction D3. The septa 310 extend vertically between an upper edge 314 and a lower edge 313. The lower edges 313 of the septa 310 correspond to the first slices 103 of the strips 100.
[0107] The multicellular body 300 also comprises a plurality of hollow protruding elements 330 having a shape that gradually extends from a base 331 to an apex 332. The hollow protruding elements 330 are present in the cells. Preferably, each cell comprises a single hollow protruding element 330. In the example illustrated in Figures 5 and 6, the hollow protruding elements 330 have a pyramidal shape. However, it does not depart from the scope of the invention if the hollow protruding elements have another shape, for example, a conical, spiral, or funnel shape. The hollow protruding elements 330 are preferably perforated at their apex 332, as illustrated in [Fig. 6].
[0108] Figure 6 illustrates an example of an acoustic attenuation panel comprising the multicellular body 300. In this case, the hollow protruding elements 330 fulfill an acoustic function.
[0109] As illustrated in [Fig. 6], the multicellular body 300 can be assembled with an acoustic skin 400. The acoustic skin 400 is in contact with the upper edges 314 of the partitions 310 of the multicellular body 300. The function of the acoustic skin 400 is to allow the passage of sound waves to be attenuated into the multicellular body 300. For this purpose, the acoustic skin 400 comprises a plurality of perforations 401.
[0110] The multicellular body 300 can also be assembled with a closing skin 500. The closing skin 500 is in contact with the lower edges 313 of the partitions 310 of the multicellular body 300. The closing skin 500 corresponds to a solid surface intended to reflect sound waves entering the multicellular body 300. The closing skin can be a constituent element of the acoustic panel, as in the example described here, or correspond to a wall of an object, for example, an aircraft engine. In the latter case, the acoustic attenuation panel does not have a closing skin and is mounted directly onto the wall of the object.
[0111] The examples described above correspond to a first variant in which the mold in the installation position comprises forming blocks distributed in rows extending along a first direction Di and in columns extending along a second direction D2 perpendicular to the first direction Dp
[0112] The invention remains within the scope of the invention if the mold in the installation position comprises forming blocks arranged differently. In particular, according to a second embodiment, the mold in the installation position may comprise forming blocks arranged along arcs of circles belonging to concentric circles. The second embodiment can be applied to both the first and second embodiments of the invention. The welding position of the mold remains the same in both the first and second embodiments.
[0113] Fig. 7 illustrates an example of mold configuration in installation position according to the second variant.
[0114] The mold 7 in this second variant comprises a plurality of conformation blocks 75. The conformation blocks 75 may each comprise an open cavity if the second variant is applied within the framework of the second embodiment of the invention.
[0115] The mold 7 comprises a plurality of rows 4a, 4b, 5a, 5b of conformation blocks 75 arranged along the radii of a principal circle CP. Each row 4a, 4b, 5a, 5b of conformation blocks 75 is arranged along a different radius of the principal circle CP. The principal circle CP has as its center point P.
[0116] For each conformation block 75, a radial direction is defined which corresponds to the direction along which the radius of the principal circle CP on which said conformation block 75 is positioned extends, and a tangential direction perpendicular to the radial direction.
[0117] The conformation blocks 75 have a first dimension along the radial direction and a second dimension along the tangential direction. The conformation blocks 75 have a height along a third direction D3 perpendicular to the radial and tangential directions. The conformation blocks 75 preferably all have the same dimensions.
[0118] The conformation blocks 75 may have a square cross-section. The conformation blocks may also have a cross-section of another shape, for example, a triangular or hexagonal cross-section. The first dimension of the conformation blocks 75 is then on average equal to the second dimension of the blocks 75. The conformation blocks 75 may also have a non-square rectangular cross-section. Preferably, all the conformation blocks 75 have the same shape.
[0119] As in the first variant, the shaping blocks 75 are movable between an installation position and a welding position. The welding position is the same for all variants of the installation position.
[0120] Figure 7 illustrates mold 7 in the installation position, i.e. mold 7 when the forming blocks 75 are in the installation position. The installation position corresponds to the position of the mold 7 or the forming blocks 75 when the strips 100 are arranged.
[0121] In the installation position, the mold 7 comprises at least a first row 4a of conformation blocks 75 and at least a second row 4b of conformation blocks 75. The first row 4a is adjacent to the second row 4b of conformation blocks 75.
[0122] The first row 4a comprises at least one first conformation block 75 and a second conformation block 75 spaced from each other in the radial direction. The second row 4b comprises at least one third conformation block 75. The first conformation block is located on a first circle Ci concentric with the principal circle CP. The second conformation block is located on a second circle C2 concentric with the principal circle CP. The third conformation block is located on a third circle C3 concentric with the principal circle CP. Thus, the first, second, and third circles have their center at point P. The first circle Ci has a smaller radius than the radius of the second circle C2. The first circle Ci has a smaller radius than the radius of the third circle C3. The third Circle C3 has a smaller radius than the radius of the second circle C2. Thus, the third circle C3 passes between the first conformation block and the second conformation block.
[0123] Preferably, as illustrated in [Fig. 7], the mold 5 comprises a plurality of first rows 4a, 5a and a plurality of second rows 4b, 5b. Each first row 4a, 5a is associated with a second row 4b, 5b. The mold 5 may comprise a regular alternation of first rows 4a, 5a and second rows 4b, 5b. Thus, in the installation position, the mold 7 comprises a plurality of row pairs, each row pair comprising a first row 4a, 5a and a second row 4b, 5b. Thus, in the installation position, the mold 7 preferably has an even number of rows of conformation blocks 75.
[0124] More generally, each first row 4a, 5a comprises a plurality of conformation blocks 75 spaced from each other in the radial direction. More particularly, each first row 4a, 5a comprises a plurality of conformation blocks 75 spaced from each other in the radial direction by a space greater than the first dimension of the conformation blocks 75.
[0125] Similarly, each second row 4b, 5b can comprise a plurality of conformation blocks 75 spaced from each other along the radial direction. More particularly, each second row 4b, 5b can comprise a plurality of conformation blocks 75 spaced from each other along the radial direction by a space greater than the first dimension of the conformation blocks 75.
[0126] The method comprises arranging the strips 100 in the mold 7 while the forming blocks 75 are in the installation position. The strips 100 are arranged in the mold 7 along the radii of the main circle CP. Each strip 100 is arranged along a different radius of the main circle CP.
[0127] The 100 strips delimit sectors of the main circle CP. In particular, the space between a first strip and a second strip defines a first sector of the main circle accommodating the first row 4a. The space between the second strip and a third strip defines a second sector of the main circle accommodating the second row 4b.
[0128] The strips 100 are arranged in the mold 7 so that the strips 100 extend widthwise along the third direction D3. The strips 100 are interposed between the rows of conformation blocks 75. Only one strip is interposed between two rows of conformation blocks 75. Each row of conformation blocks 75 is framed on both sides by one of the strips 100. At least the first or second face of each strip 100 is positioned opposite a row of blocks 75. In a conventional manner, if the mold 7 comprises n rows of blocks 75 in installation position, n+1 strips 100 are placed in the mold 7.
[0129] The strips 100 arranged in the mold 7 are held in position by positioning elements 71 and 72. The positioning elements 71 and 72 are in contact with the ends 101 and 102 of the strips 100. Thus, each strip 100 is held in position at its first end 101 by one of the positioning elements 71, 72 and held in position at its second end 102 by one of the positioning elements 71, 72. In this second embodiment, the positioning elements 71, 72 are distributed on a primary circle and a secondary circle concentric with the main circle CP in the installation position. The primary circle has a smaller radius than the secondary circle. The positioning elements 71 present on the primary circle remain on the primary circle when moving from the installation position to the welding position.At least some of the positioning elements 71 present on the secondary circle remain on the secondary circle during the transition from the installation position to the welding position. Some of the positioning elements 72 present on the secondary circle may leave the secondary circle during the transition from the installation position to the welding position to allow the tensioning of the strip 100 that they hold in position, in order to prevent the creation of unwanted creases.
[0130] The mold 7 can be preheated before the strips 100 are placed in it. Thus, when the strips 100 are placed in the mold 7, the mold 7 is at a temperature above ambient temperature. In particular, the strips 100 can be placed in the mold 7 when the mold 7 is at a temperature above 100°C. The strips 100 can be placed in the mold 7 when the mold 7 is at a temperature between 50% and 70% of the melting temperature of the thermoplastic material if said thermoplastic material is amorphous, or between 50% and 70% of the glass transition temperature of the thermoplastic material otherwise, for example, if said thermoplastic material is semi-crystalline.
[0131] The process then includes moving the shaping blocks 75 from their installation position to their welding position.
[0132] The movement of the conformation blocks 75 from their installation position to their welding position is carried out by moving the conformation blocks 75 along the circle on which they are located, so as to fuse each first row 4a, 5a with the corresponding second row 4b, 5b, and then to bring the conformation blocks together radially.
[0133] The conformation blocks 75 move along the circle on which they are located so as to merge two by two the rows 4a, 4b, 5a, 5b of conformation blocks 75. In particular, each first row 4a, 5a of conformation blocks 75 merges with one of the second rows 4b, 5b of conformation blocks 75. The conformation blocks 75 of the second rows 4b, 5b are inserted between the conformation blocks 75 of the first rows 4a, 5a. Thus, the conformation blocks 75 of the second rows 4b, 5b occupy the spaces between the conformation blocks 75 of the first rows 4a, 5a.
[0134] The first rows 4a, 5a and the second rows 4b, 5b merge to form third rows. Thus, each pair of rows forms a single third row. The welding position described previously is restored.
[0135] The multicellular body obtained by the process of the invention, for example according to the first embodiment or according to the second embodiment, can be used for a sound attenuation panel. In particular, for a sound attenuation panel for an aircraft. The multicellular body can also be used to form housings, shells, for example seat shells, or for cabin partitions. In general, the multicellular body obtained by the process of the invention can be used in any "sandwich" type structure.
[0136] The expression "between ... and ..." should be understood as including the boundaries.
Claims
Demands
1. A method for manufacturing a multicellular body (200; 300) comprising: - the arrangement of at least the first, second and third bands (100) of thermoplastic material, said first, second and third bands (100) of thermoplastic material being kept spaced apart from each other so as to delimit between the first and second bands (100) of thermoplastic material a first row (1a, 2a, 3a) and between the second and third bands (100) of thermoplastic material a second row (1b, 2b, 3b), the first row (1a, 2a, 3a) comprising at least first and second conformation blocks (55; 56) spaced apart from each other, the second row (1b, 2b, 3b) comprising at least one third conformation block (55; 56), then - the displacement of the at least third conformation block (55; 56) in the space present between the at least first and second conformation blocks (55;56) so as to form a third row (1, 2, 3) by the fusion of the first and second rows (1a, 2a, 3a, 1b, 2b, 3b), the second strip (100) of thermoplastic material being shaped into notches by said first, second and third conformation blocks (55; 56), the first and third strips (100) of thermoplastic material extending on either side of the third row (1, 2, 3) obtained, and - the approach of at least the first and second conformation blocks (55; 56) towards at least the third conformation block (55; 56), then - the welding of said at least first, second and third strips (110, 120) of thermoplastic material to each other so as to obtain a multicellular body (200; 300).
2. A manufacturing method according to claim 1, wherein the arrangement of at least the first, second, and third strips (100) of thermoplastic material is carried out such that said strips (100) of thermoplastic material are arranged along the radii of a principal circle, the first row (1a, 2a, 3a) being present in a first sector of the principal circle defined between the first and second strips (100) of thermoplastic material and the second row (1b, 2b, 3b) being present in a second sector of the main circle defined between the second and third bands (100) of thermoplastic material, the first, second and third conformation blocks (55; 56) being respectively present on a first, second and third concentric circles of the main circle, the first circle having a smaller radius than the radii of the second and third circles, the second circle having a larger radius than the third circle, in which the displacement of at least the third conformation block (55; 56) is carried out along an arc of a circle belonging to the third circle so that the first, second and third conformation blocks (55; 56) are aligned.
3. A manufacturing method according to claim 1, wherein the arrangement of the at least first, second and third strips (100) of thermoplastic material is made such that said strips (100) of thermoplastic material extend along a first direction (DJ) and are spaced apart from each other along a second direction (D2) perpendicular to the first direction (DJ), the first and second conformation blocks (55; 56) being spaced apart from each other along the first direction (Di), wherein the displacement of the at least third conformation block (55; 56) is carried out along the second direction (D2), and wherein the approach of the at least first and second conformation blocks (55; 56) towards the at least third conformation block (55; 56) is carried out along the first direction (Di).
4. A manufacturing method according to claim 3, wherein the conforming blocks (55; 56) are arranged in a staggered pattern when arranging the strips (100) of thermoplastic material.
5. A manufacturing method according to any one of claims 1 to 4, wherein the welding is carried out by heating the strips (100) of thermoplastic material to a temperature above the melting temperature of the thermoplastic material if said thermoplastic material is amorphous, above the glass transition temperature of the thermoplastic material otherwise.
6. A manufacturing method according to any one of claims 1 to 5, wherein the conformation blocks (55; 56) have a temperature above 100°C when arranging the (100) strips in thermoplastic material.
7. A manufacturing method according to any one of claims 1 to 6, wherein positioning elements (51, 52) hold the ends (101, 102) of the thermoplastic material strips (100).
8. A manufacturing method according to claim 7, wherein the positioning element(s) (51, 52) holding the second thermoplastic material band (100) exerts tension on said second thermoplastic material band (100) during the movement of the third forming block (55; 56).
9. A manufacturing method according to any one of claims 1 to 8, wherein first compression elements (53) allow the conformation blocks to be compressed in a direction perpendicular to the direction of the third row obtained and second compression elements (54) allow the conformation blocks to be compressed in a direction corresponding to the direction of the third row obtained.
10. A manufacturing method according to claim 9, wherein the first compression elements (53) comprise cutting means configured to cut the strips (100) of thermoplastic material before welding.
11. A manufacturing method according to any one of claims 1 to 10, wherein the forming blocks (56) comprise an open cavity (56a) opening onto one of the surfaces of the forming blocks (56), a die (60) comprising a plurality of teeth (60a) being arranged opposite the forming blocks (56), the teeth (60a) of the die (60) being configured to cooperate with the open cavities (56a) of the forming blocks (56), the method comprising interposing a thermoplastic film (130) extending along the first and second directions (Db D2) between the forming blocks (56) and the die (60) and then stamping said thermoplastic film (130) by making the teeth (60a) of the die (60) cooperate with the open cavities (56a) of the forming blocks (56) so as to form elements hollow projections (330) having a shape extending gradually between a base (331) and a vertex (332),THE,
12. A method further comprising welding the thermoplastic film (130) to the thermoplastic strips (100). A method for manufacturing an acoustic attenuation panel comprising producing a multicellular body (200; 300) according to any one of claims 1 to 11, and assembling the multicellular body (200; 300) with at least one acoustic skin (400).