Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
  • B29C65/02—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure
  • B29C65/34—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement"
  • B29C65/36—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" heated by induction
  • B29C65/3604—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" heated by induction characterised by the type of elements heated by induction which remain in the joint
  • B29C65/3656—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by heating, with or without pressure using heated elements which remain in the joint, e.g. "verlorenes Schweisselement" heated by induction characterised by the type of elements heated by induction which remain in the joint being a layer of a multilayer part to be joined, e.g. for joining plastic-metal laminates
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/172—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using resonance effects
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
  • B21D53/00—Making other particular articles
  • B21D53/92—Making other particular articles other parts for aircraft
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C66/00—General aspects of processes or apparatus for joining preformed parts
  • B29C66/70—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
  • B29C66/74—Joining plastics material to non-plastics material
  • B29C66/742—Joining plastics material to non-plastics material to metals or their alloys
  • B29C66/7428—Transition metals or their alloys
  • B29C66/74283—Iron or alloys of iron, e.g. steel
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B15/08—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/18—Layered products comprising a layer of metal comprising iron or steel
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
  • B32B3/10—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a discontinuous layer, i.e. formed of separate pieces of material
  • B32B3/12—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a discontinuous layer, i.e. formed of separate pieces of material characterised by a layer of regularly- arranged cells, e.g. a honeycomb structure
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
  • B32B3/26—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer
  • B32B3/266—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer characterised by an apertured layer, the apertures going through the whole thickness of the layer, e.g. expanded metal, perforated layer, slit layer regular cells B32B3/12
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B64—AIRCRAFT; AVIATION; COSMONAUTICS
  • B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
  • B64D33/00—Arrangement in aircraft of power plant parts or auxiliaries not otherwise provided for
  • B64D33/04—Arrangement in aircraft of power plant parts or auxiliaries not otherwise provided for of exhaust outlets or jet pipes
  • B64D33/06—Silencing exhaust or propulsion jets
• • G—PHYSICS
  • G10—MUSICAL INSTRUMENTS; ACOUSTICS
  • G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
  • G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
  • G10K11/162—Selection of materials
  • G10K11/168—Plural layers of different materials, e.g. sandwiches
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2260/00—Layered product comprising an impregnated, embedded, or bonded layer wherein the layer comprises an impregnation, embedding, or binder material
  • B32B2260/02—Composition of the impregnated, bonded or embedded layer
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2260/00—Layered product comprising an impregnated, embedded, or bonded layer wherein the layer comprises an impregnation, embedding, or binder material
  • B32B2260/04—Impregnation, embedding, or binder material
  • B32B2260/046—Synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/10—Properties of the layers or laminate having particular acoustical properties
  • B32B2307/102—Insulating
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/70—Other properties
  • B32B2307/732—Dimensional properties
  • B32B2307/737—Dimensions, e.g. volume or area
  • B32B2307/7375—Linear, e.g. length, distance or width
  • B32B2307/7376—Thickness
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2605/00—Vehicles
  • B32B2605/18—Aircraft

Definitions

• the present invention relates to the general field of acoustic attenuation structures. It concerns more particularly the acoustic attenuation structures used to reduce the noise produced in aircraft engines as well as in gas turbines or exhausts thereof.
• acoustic attenuation is partly achieved using acoustic panels placed at the level of the casing and the nacelle. To gain compactness on the external casing, the acoustic treatments will themselves have to become more compact. Acoustic panels are mechanical elements comparable to honeycomb boxes to attenuate the noise emitted by the engine. The shape of the cells and the thickness of these panels are studied in order to minimize engine noise pollution, more particularly in certain operating phases such as takeoff and landing. Noise reduction is an even more important issue around airports and neighboring towns.
• Acoustic attenuation structures are typically made up of an acoustic surface plate or skin permeable to the acoustic waves that it is desired to attenuate and a full reflective plate or skin called a “closing plate”, a cellular body being placed between these two walls.
• the cell body is generally made up of a set of partitions, for example in the shape of a honeycomb.
• Helmholtz-type resonators which make it possible to attenuate acoustic waves in a certain frequency range.
• Acoustic attenuation structures of this type are described in particular in documents US 5,912,442 and GB 2,314,526. However, the acoustic attenuation structures previously described only make it possible to absorb a very restricted frequency range.
• the absorbed frequency f is of the order of c/4e with e the thickness of the honeycomb and c the speed of sound.
• the processing thickness necessary to process a frequency f is of the order of c/4f.
• a cell body with a thickness of 30 mm is suitable for attenuating frequencies close to 2000 Hz, and a cell body with a thickness of 70 mm is suitable for attenuating frequencies close to 880 Hz.
• the thickness of the cell body corresponds to the distance between the permeable acoustic skin and the acoustic skin raincoat. In other words, the acoustic length of the cells is substantially equal to the height of the cellular core.
• This attenuation constraint goes against the reduction in the thickness of the structural casing and its surface area to satisfy the reduction in mass and drag.
• the size and mass of the sound attenuation structure must preferably be limited, for example when it is mounted on an aircraft.
• an acoustic panel with resonators for an aircraft propulsion assembly nacelle comprising adjacent acoustic cells which form a cellular core, each cell being extending along an axis of acoustic propagation of sound waves and comprising, inside the cell, at least one partial obstacle which extends transversely with respect to the axis of acoustic propagation and which forms an internal passage offset from the center of the cell to increase the length of the path traveled by the sound waves through the cell
• the process of manufacturing the acoustic panel comprising:
• each passage is separated from the center of the adjacent passages by a distance corresponding to the width of the acoustic cells, and each passage having a size less than the size of an acoustic cell measured in a plane perpendicular to a main direction, the main direction being parallel to the axis of acoustic propagation,
• Thermoplastic welding makes it possible to achieve local melting of the thermoplastic material and thus fusion of the cellular cores with each other and with said at least one perforated fabric.
• the alveoli, or acoustic cells can have sections, in a plane orthogonal to the direction of acoustic propagation of the sound waves, of round, hexagonal or other shape.
• Thermoplastic honeycomb cores can be formed by continuous thermoforming technology.
• the cellular cores can be made of resin such as PAEK (Polyarylether ketone), PPS (Polyphenylene sulfone), PSU (Polysulfone), PC (Polycarbonate), PA (Polyamide), PP (Polypropylene), PEI (Polyether imide).
• PAEK Polyarylether ketone
• PPS Polyphenylene sulfone
• PSU Polysulfone
• PC Polycarbonate
• PA Polyamide
• PP Polypropylene
• PEI Polyether imide
• the thermoplastic welding step comprises traction of said at least one perforated metal fabric in at least one direction perpendicular to the main direction, the tensioning allowing to stretch the canvas so that it is flatter and does not crease.
• thermoplastic welding can be induction welding or resistive welding.
• the stack forming the cellular core is introduced into a magnetic field which causes said at least one perforated metal mesh to heat up and which causes local melting of the thermoplastic material and thus a fusion of the cellular cores between them and with said at least one perforated canvas.
• the perforated wire mesh could be made of stainless steel with good magnetic properties.
• an electric current is applied to said at least one perforated metal fabric to heat the fabric(s) by the Joule effect and cause a local melting of the thermoplastic material and thus a fusion of the cellular cores between them and with said at least one perforated fabric.
• the method may further comprise, prior to the stacking step, a step of impregnating said at least one perforated metal mesh with a thermoplastic resin or a step of bonding a pure thermoplastic film to the or each perforated metal mesh.
• the preliminary impregnation step makes it possible to add thermoplastic resin to the perforated metal mesh to improve welding between the stages of the core alveolar.
• the thermoplastic resin used for impregnation is the same as that in which the cellular cores are made.
• thermoplastic welding is preferably carried out at a temperature between the glass transition temperature and the melting temperature of the thermoplastic cellular cores for amorphous thermoplastics, and at a temperature close to the melting temperature of the cellular cores for semi-crystalline thermoplastics.
• the passages of two successive perforated metal fabrics in the main direction are preferably non-aligned in the direction main.
• the fact of having passages which are never aligned two by two successively in the main direction makes it possible to maximize the path traveled by the sound wave between its entry into the cell and its exit.
• the passages can thus have a rectangular shape, an oblong shape or an oval shape.
• the step of stacking the cellular cores and said at least one perforated metal mesh preferably comprises the formation of a stack having, in the main direction , a first face and a second face, the method further comprising closing the first face of said stack with an acoustically reflective skin, and closing the second face of said stack with an acoustically transparent skin.
• the acoustically porous skin may be formed by a perforated metal fabric stretched with a perforation pattern possibly different from the other perforated metal fabrics of the acoustic panel.
• the step of forming at least one perforated metal fabric preferably comprises the use of a fabric having an acoustic resistance of 105 cm/s at least 100 rayls cgs, or 1000 Pa.s/m.
• the sound wave may not follow the non-linear path.
• Figure 1 is a schematic sectional view which illustrates a nacelle equipped with a plurality of acoustic panels according to the invention
• Figure 5 illustrates an exploded view of a cellular core of an acoustic panel of Figure 2 according to one mode of implementation of the manufacturing process of the invention.
• Figure 6 is a flowchart of a method of manufacturing one of the acoustic panels of Figure 1 according to one mode of implementation of the invention.
• Figure 1 shows a nacelle 10 equipped with a plurality of acoustic panels 12 with acoustic attenuation resonators shown schematically in strong lines. Some or all of these, or other acoustic panels, may be totally or partially equipped with cellular cores according to the invention.
• the acoustic panel 12 successively comprises, from front to rear along the longitudinal axis L, a front acoustic skin 22 which is acoustically porous to sound waves, a alveolar core 24, and a rear skin 26 that is full and therefore acoustically reflective.
• the front acoustic skin 22 and the rear skin 26 extend parallel to each other and transversely, that is to say in the transverse direction T which is orthogonal to the longitudinal direction L.
• the alveolar core 24 comprises a plurality of acoustic cells 28, or cells 28, which are joined together in the transverse direction T and the vertical direction V to form a hollow structure such as, for example, a “honeycomb” ".
• the direction of the longitudinal axis L corresponds to the direction of acoustic propagation of a sound wave entering an acoustic cell 28 via the acoustic skin 22.
• Each cell 28 is delimited by a peripheral enclosure 30 extending substantially parallel to the longitudinal direction L from the acoustic skin 22 to the rear skin 26.
• the shape of the cell 28 can be of hexagonal cross section, as can be seen see in Figure 4, or rectangular, or square, or circular, or any other geometric shape.
• cells 28 are acoustically independent.
• acoustically independent cells we consider cells whose enclosure 30 does not significantly propagate the acoustic waves from one cell 28 to another.
• These orifices are preferably in number from two to four of unitary section of the order of 1 to 4 mm 2 , and located in the enclosure 30 of the cells, in the immediate vicinity of the rear end 34 of the acoustic core against the rear skin 26.
• Obstacles are said to be opaque to acoustic waves, but can however be provided with a drainage device for the evacuation of liquids, preferably made by one or two orifices per obstacle and with a section of the order of 1 to 2 mm 2 each.
• each cell 28 comprises at least a first partial obstacle 36 and even, in this example, a second partial obstacle 38 which extend generally in the direction transversal T from the enclosure 30 of the cell 28.
• the obstacles 36 and 38 extend in a plane perpendicular to the main axis of the associated cell 28, the main axis of the cell 28 being coincident with the direction of the longitudinal axis L.
• each obstacle 36, 38 has a free end edge 40 which delimits a passage 42 with the wall 30 opposite, to allow the passage of sound waves which enter the associated cell 28.
• the obstacles 36, 38 are offset in depth along the main longitudinal axis L of the associated cell 28.
• each obstacle 36, 38 is adapted so that the obstacles 36, 38 partly overlap in a longitudinal projection view on a surface perpendicular to the longitudinal direction.
• the sound waves follow a sinuous trajectory between the obstacles 36, 38, from the front end 32 to the rear end 34 of the associated cell 28.
• This sinuous trajectory is therefore longer than the straight line distance between the two end faces 32 and 34.
• a cell 28 of 30 millimeters in longitudinal thickness which includes two obstacles 36 and 38 extending over approximately two thirds of the section of the associated cell 28, is equivalent to a cell without obstacle of 64 millimeters in width.
• longitudinal thickness in terms of noise attenuation relative to a given frequency.
• each cell 28 includes a third obstacle 44
• the three obstacles 36, 38, 44 have dimensions such as two successive obstacles in the longitudinal direction, have a cumulative surface area greater than the section of the cell and a projected surface covering the entire section.
• the obstacles are arranged to impose a winding path on the sound waves which travel through the associated cell 28, as shown by arrow F.
• a cell 28 of 30 millimeters in longitudinal thickness which comprises three obstacles 36, 38 and 44 each extending over approximately two thirds of the section of the associated cell as illustrated in Figure 3, the successive obstacles being attached to opposite walls, is equivalent to an obstacle-free cell of 70 millimeters of longitudinal thickness, in terms of noise attenuation compared to another frequency considered.
• the cells 28 are made of thermoplastic composite material and the obstacles are made of metallic material. Also, the obstacles 36, 38 can be welded to the material forming the cells 28.
• the cellular core 24 comprises a first cellular core 110, a second third cellular core 120 and a third cellular core 130, respectively having a cell height Hn 0 , H120, HI 30 , the height being measured in the longitudinal direction L
• the three heights Hn 0 , H120, HI 30 can be equal or different.
• the height Hno of the first cellular core 110 is lower than those of the second and third cellular cores 120 and 130, these two cellular cores 120 and 130 having an equal cell height.
• the cellular cores 110, 120 and 130 have partial cells 112, 122, 132 having a width of between 0.95 and 2.5 cm and a height of between 5 and 30 mm, the cells of the same cellular core all having the same width and all the same height.
• the first perforated metal mesh 102 includes perforations 102c forming passages for sound waves.
• the number of perforations 102c corresponds to the number of cells 28 of the alveolar core 24, and therefore to the number of partial cells 112, 122, 132 of each alveolar core 110, 120, 130.
• Each perforation 102c is spaced from another adjacent perforation 102c by a length equal to the width of a cell 112, 122, 132 measured in a plane comprising the transverse direction T and the vertical direction V.
• the second perforated metal fabric 103 comprises, in the longitudinal direction L, a first longitudinal end 103a and a second longitudinal end 103b.
• the first longitudinal end 103a faces the lower longitudinal end 120b of the second cellular core 120 and the second longitudinal end 103b faces the upper longitudinal end 130a of the third longitudinal core 130.
• the second perforated metal fabric 103 comprises perforations 103c forming passages for sound waves.
• the number of perforations 103c corresponds to the number of cells 28 of the alveolar core 24, and therefore to the number of partial cells 112, 122, 132 of each alveolar core 110, 120, 130.
• the perforations 103c of the second perforated metal fabric 103 and the perforations 102c of the first perforated metal fabric 102 are off-center. Thus, no perforation 103c of the second perforated metal fabric 103 is aligned with a perforation 102c of the first perforated metal fabric 102.
• the perforations 102c and 103c of the first and second perforated metal fabrics have elliptical shapes in the example illustrated in Figure 5.
• a first cellular core 110, a second cellular core 120 and a third cellular core 130 are formed in thermoplastic resin.
• the second perforated metal fabric 103 is stacked successively from front to back in the longitudinal direction L on the third cellular core 130, then the second cellular core 120 on the second perforated metal fabric 103, then the first fabric perforated metal core 102 on the second cellular core 120, and finally the first cellular core 110 on the first perforated metal fabric 102.
• the stack is adjusted so that the partial cells 111, 121, 131 are aligned in the longitudinal direction L, i.e. that is to say so that each set of three partial cells 111, 121 and 131 forms a cell 28, and so that each perforation 102c and 103c is inside a cell 28.
• the third step 610 may include the addition of a solid rear skin 26 at the rear of the stack, and the addition of an acoustic skin 22 at the front of the stack in the longitudinal direction L. L The addition of these two skins can also be carried out after the thermoplastic welding of the fifth step.
• the stack thus obtained has a height measured in the longitudinal direction L of between 15 and 200 mm and typically 60 mm.
• Thermoplastic welding is induction welding or resistive welding. It allows local melting of the thermoplastic material and thus fusion of the cellular cores 110, 120, 130 with each other and with the perforated metal fabrics 102 and 104.
• the stack forming the cellular core 24 is introduced into a magnetic field which causes the perforated metal fabrics 102 and 103 to heat up.
• Thermoplastic welding is carried out at a temperature between the glass transition temperature and the melting temperature of the thermoplastic cellular cores.
• the temperature is controlled by the electric current applied to said at least one perforated metal mesh in the case of resistive welding (typically with a power density of 5 to 50 W/cm 2 ), while, in the case of magnetic welding, the temperature is controlled by the magnetic power (the efficiency depending on the choice of inductor).
• the fifth thermoplastic welding step may include traction of the perforated metal fabrics in the transverse direction T and/or the vertical direction V.
• Thermoplastic welding ends with cooling of the stack after which the assembly formed by the stack is welded together.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Aviation & Aerospace Engineering (AREA)
• Physics & Mathematics (AREA)
• Acoustics & Sound (AREA)
• Multimedia (AREA)
• Crystallography & Structural Chemistry (AREA)
• Inorganic Chemistry (AREA)
• Soundproofing, Sound Blocking, And Sound Damping (AREA)

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• 2022
  • 2022-10-26 FR FR2211159A patent/FR3141551B1/fr active Active
• 2023
  • 2023-10-16 US US19/124,643 patent/US20260008238A1/en active Pending
  • 2023-10-16 EP EP23809701.8A patent/EP4609384A1/de active Pending
  • 2023-10-16 WO PCT/FR2023/051609 patent/WO2024089342A1/fr not_active Ceased
  • 2023-10-16 CN CN202380075962.0A patent/CN120153417A/zh active Pending

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