Producing a multicellular body from strips of thermoplastic material
The method of arranging and welding thermoplastic strips using conformation blocks addresses the challenge of achieving thin, consistent partitions in acoustic attenuation panels, ensuring high material quality and cost-effectiveness.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- SAFRAN SA
- Filing Date
- 2025-11-12
- Publication Date
- 2026-05-21
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 multicellular bodies, with controlled geometric tolerances and excellent material quality, utilizing staggered patterns and controlled temperature welding to optimize the process.
The method achieves controlled geometric tolerances and excellent material quality, enabling the production of multicellular bodies with thin partitions at reduced costs, suitable for acoustic attenuation panels.
Smart Images
Figure FR2025051043_21052026_PF_FP_ABST
Abstract
Description
Description Title of the invention: Fabrication of a multicellular body from strips of thermoplastic material Technical Field
[0001] The present invention relates to the manufacture of multicellular bodies, for example the manufacture of multicellular bodies for acoustic attenuation panels. Previous technique
[0002] Acoustic attenuation panels typically consist of a surface plate or skin with acoustic permeability to the sound waves to be attenuated, and a solid, reflective plate or skin known as the "closing plate or skin," with at least one multicellular body positioned between these two surfaces. The multicellular body is generally composed of a series of partitions forming a rib network and delimiting a plurality of cells. As is well known, such panels form Helmholtz resonators, which attenuate sound waves within a specific frequency range.
[0003] It is also well known to incorporate hollow acoustic elements, such as open truncated cones, within the cells of the multicellular body. These hollow acoustic elements allow for the processing of low frequencies without requiring 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 typically manufactured 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, all 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 thermoplastic strips, said first, second and third thermoplastic strips being kept spaced apart from each other so as to delimit a first row between the first and second thermoplastic strips and a second row between the second and third thermoplastic strips, the first row comprising at least first and second conformation blocks spaced apart from each other, the second row comprising at least one third conformation block, then
[0008] - the displacement of at least the third conformation block in the 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 convergence of at least the first and second conformational blocks towards at least the third conformational block, then
[0010] - welding said at least first, second and third strips of thermoplastic material together so as to obtain a multicellular body.
[0011] According to a first variant, 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 strips of thermoplastic material, said first, second and third strips 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 along the first direction, the second row comprising at least a third conformation block, then
[0013] - the displacement of the at least third conformation block along 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 notches 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 conformational blocks towards at least the third conformational block, then
[0015] - welding said at least first, second and third strips of thermoplastic material together so as to obtain a multicellular body.
[0016] According to a second variant, in which 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 so that the first, second and third conformation blocks are aligned.
[0017] Thus, the geometric tolerances of the resulting multicellular body are controlled even at low thicknesses, 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 strips of thermoplastic material, the conforming blocks may exhibit 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] Therefore, the temperature of the blocks is not too high to avoid prematurely melting the strips, but sufficient to optimize the process cycle time. Indeed, the forming blocks can reach the temperature required for strip welding more quickly.
[0023] According to another particular embodiment of the invention, positioning elements hold the ends of the thermoplastic material strips in place.
[0024] Thus, the shaping of the thermoplastic material strips is simplified.
[0025] According to another particular embodiment of the invention, the positioning element(s) holding the second thermoplastic material band exert tension on said second thermoplastic material band during the movement of the third conforming block.
[0026] Thus, the thermoplastic strip(s) intended to be shaped into crenellations are put under tension so as to avoid the formation of creases 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 in the multicellular body are easier to control. The compression elements also help to partially ensure the sealing of the mold that holds the thermoplastic strips, particularly to prevent the thermoplastic material from leaking out of the mold.
[0030] According to another particular embodiment of the invention, the first compression elements include cutting means configured to cut the strips of thermoplastic material before welding.
[0031] Thus, it is possible to cut off the portions of the thermoplastic material strips that protrude from the forming blocks.
[0032] According to a second embodiment of the invention, the shaping blocks comprise an open cavity opening onto one of the surfaces of the shaping blocks, a die comprising a plurality of teeth being arranged opposite the shaping blocks, the teeth of the die being configured to cooperate with the open cavities of the shaping blocks, the method comprising interposing a thermoplastic film extending in the first and second directions between the shaping blocks and the die and then stamping said thermoplastic film by making the teeth of the die cooperate with the open cavities of the shaping blocks so as to form hollow protruding elements having a shape extending progressively between a base and a top, the method further comprising welding the thermoplastic film to the thermoplastic strips.
[0033] The invention also relates to a method for 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] Figure 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] Figure 2 is a schematic top view of the strips of Figure 1 arranged in the mold during the approach of the conformation blocks along the second direction.
[0036] [Fig. 3] Figure 3 is a schematic top view of the strips of figures 1 and 2 arranged in the mold in welding position.
[0037] [Fig. 4] Figure 4 is a schematic perspective view of a multicellular body obtained according to the first embodiment of the invention.
[0038] [Fig. 5] Figure 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] Figure 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] Figure 7 is a schematic top view of a plurality of strips arranged in a mold in installation position according to a second variant. Description of the implementation methods
[0041] Figures 1 to 5 illustrate two examples of a manufacturing process for 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 the supply of a plurality of 100 strips of thermoplastic material.
[0043] 100-gauge strips can be obtained by cutting a thermoplastic film. These strips can be less than 0.5 mm thick, or even less than 0.3 mm. Specifically, they can be between 0.1 mm and 0.3 mm thick. They can also be between 20 mm and 50 mm wide, 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 100 bands may be selected, in particular but not exclusively, from the following materials: polyaryletherketones (PAEK) such as polyetheretherketone (PEEK) and the Polyetherketoneketone (PEKK), polyetherimides (PEI), polycarbonate (PC), polyphenylene sulfide (PPS), polyethersulfone (PESU), polyphenylsulfone (PPSU), and polysulfones (PSU) are all types of thermoplastic materials. These materials can be filled with particles and / or fibers, or be unfilled.
[0046] The process also includes the provision of a mold 5.
[0047] Mold 5 comprises a plurality of conformation blocks 55. The conformation blocks 55 are arranged in rows and columns. Mold 5 comprises a plurality of rows 1a, 1b, 2a, 2b, 3a, 3b of conformation blocks 55. The rows 1a, 1b, 2a, 2b, 3a, 3b of conformation blocks 55 extend along a first direction Di. The columns of conformation blocks 55 extend along a second direction D2. The second direction D2 is perpendicular to the first direction Di.
[0048] The 55 conformation blocks have a first dimension along the first direction Di and a second dimension along the second direction D2. The 55 conformation blocks have a height along a third direction D3 perpendicular to the first and second directions Di and D2. The 55 conformation blocks preferably all have the same dimensions.
[0049] Conformation blocks 55 may have a square cross-section. They may also have a cross-section of another shape, such as a triangle or hexagon. The first dimension of the 55 conformation blocks is then, on average, equal to the second dimension. Conformation blocks 55 may also have a non-square rectangular cross-section. Preferably, all 55 conformation blocks have the same shape.
[0050] The 55 conformation blocks are mobile between an installation position and a welding position.
[0051] Figure 1 illustrates the mold 5 in the installation position, that is, the mold 5 when the forming blocks 55 are in the 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 Figure 5 presents 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 the 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 lb of conformation blocks 55. The first row la is adjacent to the second row lb of conformation blocks 55.
[0053] The first row la comprises at least one first conformation block and a second conformation block spaced apart along the first direction Di. The second row lb comprises at least one third conformation block.
[0054] Preferably, as illustrated in Figure 1, the mold 5 comprises a plurality of first rows la, 2a, 3a and a plurality of second rows lb, 2b, 3b. Each first row la, 2a, 3a is associated with a second row lb, 2b, 3b. The mold 5 may include a regular alternation of first rows la, 2a, 3a and second rows lb, 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 lb, 2b, 3b. Thus, in the installation position, the mold 5 preferably has an even number of rows of blocks with conformation 55.
[0055] In the installation position, each first row la, 2a, 3a comprises at least two conformation blocks spaced apart along the first direction Di. Each second row lb, 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 Di. 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 lb, 2b, 3b can comprise a plurality of conformation blocks 55 spaced from each other along the first direction Di. More specifically, each second row lb, 2b, 3b can comprise 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.
[0058] In the installation position, the conformation blocks 55 are arranged in a staggered pattern. The conformation blocks 55 in the first rows (la, 2a, 3a) are offset from the conformation blocks 55 in the second rows (lb, 2b, 3b) in the installation position. Thus, each conformation block 55 in one of the first rows (la, 2a, 3a) is adjacent to a space in the second row (lb, 2b, 3b) belonging to the same pair of rows. In particular, each conformation block 55 in 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 relative to 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 includes 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 Di. 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 any two rows of forming blocks 55. Each The row of conforming blocks 55 is framed on either side along the second direction D2 by one of the strips 100. Except for the strips 100 located 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. Typically, if the mold 5 has 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. These positioning elements 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 and 52, and held in position at its second end 102 by one of the positioning elements 51 and 52. At least some of the positioning elements 51 are fixed along the first direction Di. Some of the positioning elements 52 may be movable along the first direction Di to allow tensioning of the strip 100 they are holding in position, in order to prevent the formation of unwanted creases. Preferably, each strip 100 is held by at least one fixed positioning element 51.Thus, each band 100 is held by two fixed position retaining elements 51 at each end 101, 102, or by one fixed position retaining element 51 at one end 101, 102 and by one mobile position retaining 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 higher than ambient. 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 material's melting point. thermoplastic 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.
[0063] Mold 5 is preferably heated by induction. This heating method allows for low energy consumption and enables rapid attainment of the desired temperature. However, mold 5 can also be heated using a heat transfer fluid or heating cartridges.
[0064] The process then includes moving the shaping blocks 55 from their installation position to their welding position, as illustrated in Figures 2 and 3.
[0065] 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.
[0066] 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.
[0067] The movement of conformation blocks 55 along the first direction Di preferably begins after the movement of conformation blocks 55 along the second direction D2 has begun. The movement of conformation blocks 55 along the first direction Di may begin after the movement of conformation blocks 55 along the second direction D2 has ended. The movement of conformation blocks 55 along the first direction Di may begin after the movement of conformation blocks 55 along the second direction D2 has begun but before the movement of conformation blocks 55 along the second direction D2 has ended. The movement of conformation blocks 55 along the first direction Di ends after the movement of conformation blocks 55 along the second direction D2 has ended.
[0068] The displacement of the conformation blocks 55 along the second direction D2 includes the displacement of at least one of the blocks from one of the first rows la, 2a, 3a following the second direction D2 in the space present between two blocks of conformation 55 of the corresponding second row lb, 2b, 3b.
[0069] The conformation blocks 55 move along the second direction D2 so as to merge the rows la, lb, 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 lb, 2b, 3b of conformation blocks 55. The conformation blocks 55 of the second rows lb, 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 lb, 2b, 3b occupy the spaces between the conformation blocks 55 of the first rows la, 2a, 3a.
[0070] The first rows la, 2a, 3a and the second rows lb, 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 lb, 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 lb, 2b, 3b.
[0071] The band(s) 100 present between two rows of fused conformation blocks 55 are shaped into crenellations by the conformation blocks 55. This results in crenellated bands 120.
[0072] 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.
[0073] The crenellated bands 120 are preferably held by at least one movable retaining element 52 along the first direction Di, in order to facilitate the shaping of the crenellations without creases.
[0074] The 100 strip(s) between the pairs of rows remain straight. The 100 strip(s) between the pairs of rows are not placed in formed by the conformation blocks 55. Straight bands 110 are thus preserved. The straight bands 110 extend only along the first direction Di.
[0075] This results in a regular alternation of crenellated bands 120 and straight bands 110. Each crenellated band 120 is framed by two straight bands 110 following the second direction D2.
[0076] The straight bands 110 are preferably held only by fixed retaining elements 51 along the first direction Di. The straight bands 110 are not held by movable retaining elements 52 along the first direction Di.
[0077] 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 bands 110 and the crenellated bands 120 are not deformed at their ends 101, 102.
[0078] Displacing the conformation blocks 55 along the second direction D2 also compresses the bands 100 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.
[0079] As illustrated in Figure 3, the mold 5 can 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 can come into contact with a straight strip 110 in the welding position. The first compression elements 53 can allow the mold 5 to be closed along the second direction D2. The first compression elements 53 can apply pressure along the second direction D2 by means of one or more jacks, or by means of a press.
[0080] The movement of 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.
[0081] As illustrated in Figure 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, every 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 be used to close the mold 5 along the first direction Di.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.
[0082] 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.
[0083] The first compression elements 53 can be configured to provide 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 provide a seal to the thermoplastic material along the first direction Di during the manufacturing process of the multicellular body.
[0084] 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.
[0085] When the mold 5 is closed in the welding position, the crenellated strips 120 and the straight strips 110 are welded together. The welding of the crenellated strips 120 and the straight strips 110 can be carried out in several ways. Preferably, the welding is performed by heating the crenellated 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 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.
[0086] Induction heating is the preferred method for welding. This heating method offers low energy consumption and allows the desired temperature to be reached quickly. However, welding can also be heated using a heat transfer fluid or heating cartridges.
[0087] When the welding of the crenellated strips 120 and the straight strips 110 is carried out, a multicellular body 200 is obtained.
[0088] 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.
[0089] This results in a multicellular body 200, as illustrated in Figure 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 conformational blocks 55 used. Thus, the cells can, for example, also have a triangular or hexagonal shape.
[0090] 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.
[0091] 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 a top. The lower edges 213 of the partitions 210 are intended to be in contact with an acoustic skin, a closing skin, or a wall.
[0092] Figures 5 and 6 illustrate an example of a manufacturing process for 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.
[0093] 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 each comprise 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.
[0094] 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.
[0095] 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.
[0096] 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.
[0097] Similarly, the conformation blocks 56 are moved as described in the first embodiment of the invention to reach a welding position.
[0098] Unlike the first embodiment of the invention, in the second embodiment of the invention, the mold 6 is not closed by a top plate.
[0099] 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 shapes the thermoplastic film 130 to obtain hollow protruding elements 330 inside the cells of the multicellular body 130. The compression of the die 60 against the conformation blocks 56 closes the mold 6.
[0100] The thermoplastic material used for the 130 film may be selected, 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 unfilled with particles and / or fibers.
[0101] The 130 thermoplastic film can be made from the same material as the 100 strips. This makes it easier to ensure a good quality weld between the 130 film and the 100 strips. However, the 130 thermoplastic film can also be made from a different material than the 100 strips.
[0102] 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 fulfill an acoustic function.
[0103] 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.
[0104] 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.
[0105] 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. Preferably, the welding is performed by heating the crenellated 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 temperatures, each is heated to a temperature higher than its glass transition and / or melting temperature. The strips can be heated by bringing the mold 5 to a temperature higher than the... The melting point of the thermoplastic material, if amorphous, is higher than its glass transition temperature otherwise. Welding can also occur at the contact points between strips, or between the strips and the film.
[0106] 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.
[0107] 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.
[0108] This results in a multicellular body 300 as illustrated in Figure 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.
[0109] The multicellular body 300 also comprises a plurality of hollow projecting elements 330 having a shape that gradually extends from a base 331 to an apex 332. The hollow projecting elements 330 are present within the cells. Preferably, each cell comprises a single hollow projecting element 330. In the example illustrated in Figures 5 and 6, the hollow projecting elements 330 have a pyramidal shape. However, it does not depart from the scope of the invention if the hollow projecting elements have another shape, for example, a conical, spiral, or funnel shape. The hollow projecting elements 330 are preferably perforated at their apex 332, as illustrated in Figure 6.
[0110] 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. [YES] As illustrated in Figure 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 sound waves to be attenuated to pass into the multicellular body 300. For this purpose, the acoustic skin 400 comprises a plurality of perforations 401.
[0112] 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 is a solid surface designed to reflect sound waves entering the multicellular body 300. The closing skin can be a component of the acoustic panel, as in the example described here, or it can be 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.
[0113] The examples described above correspond to a first variant in which the mold in the installation position includes conformation blocks distributed in rows extending along a first direction Di and in columns extending along a second direction D2 perpendicular to the first direction Di.
[0114] The invention remains within the scope of the invention if the mold in the installation position comprises differently arranged forming blocks. 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. This 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.
[0115] Figure 7 illustrates an example of mold configuration in installation position according to the second variant.
[0116] 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.
[0117] 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 its center at point P.
[0118] 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.
[0119] The 75 conformation blocks have a first dimension along the radial direction and a second dimension along the tangential direction. The 75 conformation blocks also have a height along a third direction D3 perpendicular to the radial and tangential directions. Preferably, all 75 conformation blocks have the same dimensions.
[0120] Conformation 75 blocks can have a square cross-section. They can also have a cross-section of another shape, such as a triangle or hexagon. In this case, the first dimension of the 75 blocks is, on average, equal to the second dimension. Conformation 75 blocks can also have a non-square rectangular cross-section. Preferably, all 75 blocks have the same shape.
[0121] As in the first variant, the 75 conformation blocks are movable between an installation position and a welding position. The welding position is the same for all installation position variants.
[0122] Figure 7 illustrates mold 7 in the installation position, that is, mold 7 when the forming blocks 75 are in the installation position. The position installation corresponds to the position of the mold 7 or the conforming blocks 75 when arranging the strips 100.
[0123] 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.
[0124] The first row 4a comprises at least one first conformation block 75 and a second conformation block 75 spaced radially apart. The second row 4b comprises at least one third conformation block 75. The first conformation block lies on a first circle Ci concentric with the principal circle CP. The second conformation block lies on a second circle C2 concentric with the principal circle CP. The third conformation block lies on a third circle C3 concentric with the principal circle CP. Thus, the first, second, and third circles are centered at point P. The first circle Ci has a smaller radius than the second circle C2. The first circle Ci has a smaller radius than the third circle C3. The third circle C3 has a smaller radius than the second circle C2.Thus, the third circle C3 passes between the first conformation block and the second conformation block.
[0125] Preferably, as illustrated in Figure 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 include 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 blocks with conformation 75.
[0126] More generally, each first row 4a, 5a comprises a plurality of blocks of conformation 75 spaced from each other along the radial direction. More particularly, each first row 4a, 5a comprises a plurality of conformation blocks 75 spaced apart from each other along the radial direction by a space greater than the first dimension of the conformation blocks 75.
[0127] Similarly, each second row 4b, 5b can comprise a plurality of conformation blocks 75 spaced from each other in the radial direction. More specifically, each second row 4b, 5b can comprise a plurality of conformation blocks 75 spaced from each other in the radial direction by a spacing greater than the first dimension of the conformation blocks 75.
[0128] The process involves arranging the 100 strips in the mold 7 while the forming blocks 75 are in the installation position. The 100 strips are arranged in the mold 7 along the radii of the main circle CP. Each 100 strip is arranged along a different radius of the main circle CP.
[0129] The 100 strips delineate sectors of the main circle CP. In particular, the space between the first and second strips defines the first sector of the main circle, which contains the first row 4a. The space between the second and third strips defines the second sector of the main circle, which contains the second row 4b.
[0130] The strips 100 are arranged in the mold 7 so that they 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 any 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. Typically, if the mold 7 has n rows of blocks 75 in the installation position, n+1 strips 100 are placed in the mold 7.
[0131] The strips 100 arranged in the mold 7 are held in position by positioning elements 71 and 72. These 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 and 72, and held in position at its second end 102 by one of the positioning elements 71 and 72. In this In the second variant, the positioning elements 71 and 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 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 on the secondary circle remain on the secondary circle when moving from the installation position to the welding position. Some of the positioning elements 72 on the secondary circle may leave the secondary circle when moving from the installation position to the welding position to allow tensioning of the strip 100 that they hold in position, thus preventing the formation of unwanted creases.
[0132] 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.
[0133] Mold 7 is preferably heated by induction. This heating method allows for low energy consumption and enables the desired temperature to be reached quickly. However, mold 7 can also be heated using a heat transfer fluid or heating cartridges.
[0134] The process then includes moving the shaping blocks 75 from their installation position to their welding position.
[0135] The movement of the shaping blocks 75 from their installation position to their welding position is achieved by moving the shaping blocks 75 along the circle on which they are located, so as to fuse each first row Tl 4a, 5a with the corresponding second row 4b, 5b, then bring the conformation blocks together radially.
[0136] The conformation blocks 75 move along the circle on which they are located so as to merge the rows 4a, 4b, 5a, 5b of conformation blocks 75 in pairs. 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.
[0137] 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.
[0138] The multicellular body obtained by the process of the invention, for example according to the first embodiment or 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.
[0139] 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 (la, 2a, 3a) and between the second and third bands (100) of thermoplastic material a second row (lb, 2b, 3b), the first row (la, 2a, 3a) comprising at least first and second conformation blocks (55; 56) spaced apart from each other, the second row (lb, 2b, 3b) comprising at least one third conformation block (55; 56), then - the displacement of at least the third conformation block (55; 56) in the space between at least the 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 conformational blocks (55; 56) towards at least the third conformational 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 thermoplastic strips (100) is carried out such that said thermoplastic strips (100) 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 bands (100) of thermoplastic material and the second row (lb, 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 (Di) and are spaced apart from each other along a second direction (D2) perpendicular to the first direction (Di), 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 conforming blocks (55; 56) have a temperature greater than 100°C when the thermoplastic material strips (100) are arranged.
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 conformation blocks (56) comprise an open cavity (56a) opening onto one of the surfaces of the conformation blocks (56), a die (60) comprising a plurality of teeth (60a) being arranged opposite the conformation blocks (56), the teeth (60a) of the die (60) being configured to cooperate with the open cavities (56a) of the conformation blocks (56), the method comprising the interposition of a film (130) of material thermoplastic extending along the first and second directions (Di, D2) between the conforming blocks (56) and the die (60) and then stamping said film (130) in thermoplastic material by cooperating the teeth (60a) of the die (60) with the open cavities (56a) of the conforming blocks (56) so as to form hollow protruding elements (330) having a shape extending progressively between a base (331) and a top (332), the process further comprising welding the film (130) in thermoplastic material to the strips (100) in thermoplastic material.
12. Method of manufacturing an acoustic attenuation panel comprising making 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).