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
  • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
  • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
  • B29C70/28—Shaping operations therefor
  • B29C70/40—Shaping or impregnating by compression not applied
  • B29C70/42—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles
  • B29C70/44—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles using isostatic pressure, e.g. pressure difference-moulding, vacuum bag-moulding, autoclave-moulding or expanding rubber-moulding
  • B29C70/443—Shaping or impregnating by compression not applied for producing articles of definite length, i.e. discrete articles using isostatic pressure, e.g. pressure difference-moulding, vacuum bag-moulding, autoclave-moulding or expanding rubber-moulding and impregnating by vacuum or injection
• • 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
  • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
  • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
  • B29C70/06—Fibrous reinforcements only
  • B29C70/08—Fibrous reinforcements only comprising combinations of different forms of fibrous reinforcements incorporated in matrix material, forming one or more layers, and with or without non-reinforced layers
  • B29C70/086—Fibrous reinforcements only comprising combinations of different forms of fibrous reinforcements incorporated in matrix material, forming one or more layers, and with or without non-reinforced layers and with one or more layers of pure plastics material, e.g. foam layers
• • 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
  • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
  • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
  • B29C70/28—Shaping operations therefor
  • B29C70/30—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core
  • B29C70/34—Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core and shaping or impregnating by compression, i.e. combined with compressing after the lay-up operation
• • 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
  • B29C70/00—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts
  • B29C70/04—Shaping composites, i.e. plastics material comprising reinforcements, fillers or preformed parts, e.g. inserts comprising reinforcements only, e.g. self-reinforcing plastics
  • B29C70/28—Shaping operations therefor
  • B29C70/54—Component parts, details or accessories; Auxiliary operations, e.g. feeding or storage of prepregs or SMC after impregnation or during ageing
  • B29C70/545—Perforating, cutting or machining during or after moulding
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
  • B29D99/00—Subject matter not provided for in other groups of this subclass
  • B29D99/001—Producing wall or panel-like structures, e.g. for hulls, fuselages, or buildings
  • B29D99/0021—Producing wall or panel-like structures, e.g. for hulls, fuselages, or buildings provided with plain or filled structures, e.g. cores, placed between two or more plates or sheets, e.g. in a matrix
• • 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
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
  • B29K2105/04—Condition, form or state of moulded material or of the material to be shaped cellular or porous
  • B29K2105/043—Skinned foam

Definitions

• the present invention relates to a method of manufacturing an acoustic attenuation panel, particularly for aeronautics.
• Prior art is known acoustic panels with honeycomb core, sandwiched between an acoustic skin provided with perforations and a support skin.
• the acoustic skin usually made of composite material, must be polymerized and then pierced before being assembled on the honeycomb core: a draping with this skin on the soul is indeed not possible in because of the risk of appearance of facets caused by the alveoli of the soul during the pressurization of this soul on the acoustic skin (phenomenon of "telegraphing"); moreover, a piercing of this skin after its polymerization on the soul would inevitably lead to the damage of certain parts of the soul.
• the acoustic skin during the bonding phase with the core has holes which are blocked by the adhesive or the resin, reducing the effective sound attenuation treatment surface.
• the present invention is intended to overcome such a specific tooling and manufacturing cycle.
• This object of the invention is achieved with a method of manufacturing an acoustic attenuation panel in which at least one foam roll is taken, at least the acoustic surface of this foam roll is coated with a fresh composite material. and perforations are made in the coating thus produced. Thanks to this process, it is therefore no longer necessary to provide a preliminary phase, or specific tooling, manufacturing (polymerization + drilling) acoustic skin: it is actually the foam bread that is, by its relative rigidity, the acoustic skin molding tool, without the risk of appearance of facets (because the foam roll is full, unlike cells of the honeycomb).
• step E perforates the acoustic face thus polymerized; prior to step B), the opposite side of the foam cake is also draped, taking care to overflow and join the folds of composite material applied on both sides;
• Counter molds may be used to ensure the cohesion of the folds of composite material on the edges of said foam roll; - The molding is carried out by molding said composite material on said foam roll, that is to say that one:
• A) places said roll of composite material between the two halves of a mold, providing a space especially between the acoustic face of said bread and one of the two mold halves, B) injects a thermoplastic or thermosetting resin possibly loaded into the space defined by said half-molds,
• the two half-molds are rigid
• one half-mold is rigid and the other half-mold is formed by a bladder able to be placed under vacuum;
• said perforations are made by molding said composite material, thanks to pins formed on one of the half-molds or on the acoustic face of the foam roll;
• perforations are made by piercing said polymerized composite material after opening said mold;
• said acoustic panel is made by means of several foam bars
• Figures 7 to 16 show, in sectional view (with the exception of Figures 12a and 12b, which show a top view of the element shown in Figure 12), the various steps of a second variant of the method according to the invention, and
• FIGS. 17 to 21 represent different options of the method according to the invention, applicable to both the first and second variants mentioned above.
• a mouse roll 1 substantially in the form of a curved foam plate.
• the foam of the present invention is a relatively rigid material having an open structure, i.e. having many communicating cells, conforming to this material acoustic absorption characteristics.
• This foam can be formed from metal, polymer, ceramic or composite material available on the market.
• the foam roll 1 is intended to absorb the acoustic waves in a zone of an aircraft engine nacelle, but it goes without saying that this example is in no way limiting.
• the acoustic face 3 of the foam roll 1, that is to say the face of this foam roll which is intended to be exposed to the sound source whose acoustic energy is to be absorbed, is in this case located at the top of the attached drawing sheet.
• the foam roll 1 has a specific shape that can notably incorporate one or more cavities 5, making this foam roll suitable for a particular installation inside an engine nacelle. plane.
• the procedure is as follows.
• the organic material may typically comprise carbon fibers, and the resin may typically comprise an epoxy resin.
• the foam roll 1 is then pressed against this draped material 9.
• backing molds 21, 23 may be provided on the periphery of the foam roll 1, so that the emptying bladder 19 exerts a sufficient pressure force on the zone 15, 17 of the folds of composite material 9, 13.
• the assembly thus obtained is then autoclaved and polymerized at a temperature suitable for the resin used.
• This migration is interesting because it allows an intimate association of folds of composite material, with. the foam, and therefore excellent cohesion of the whole.
• the perforation carried out by means of the tool 25 must take into account the migration thickness of the resin in the foam, so as to allow perfect communication between the exterior of the acoustic panel thus produced and the foam forming the bread 1.
• the panel obtained may be placed for example inside an engine nacelle, for example in the zone of the air inlet lip. of this nacelle or on the engine hood.
• a molding tool 7 comprising two rigid half-molds 7a, 7b, whose shapes are adapted to match those of the foam roll 1, while providing a gap 29 at least between the acoustic face of the foam roll 1 and the associated half-mold 7a (FIG. 9).
• the gap 29 extends on both sides of the foam bar 1, the pins 31 being used to maintain a gap between the lower face (that is to say opposite to the acoustic face) of this foam roll 1 and the associated half-mold 7b.
• a rigid half-mold and a flexible half-mold are adapted to perform a vacuum of the space between the two half-molds:
• a suitable flexible half-mold may be a vacuum bladder.
• VARTM Vacuum Assisted Resin Transfer Molding
• FIGS. 12 to 16 Another alternative for making the perforations inside the acoustic skin 9 is illustrated in FIGS. 12 to 16.
• the foam roll 1 is machined so that its acoustic face is provided with a pattern of rectangular foam pads 33 (FIG. 12a) or hexagonal pins 35 (FIG. 12b), or any other appropriate form.
• FIG. 14 further shows that it can be envisaged that the separation of the foam roll 1 with respect to the half-mold 7b is carried out not by pins 31 as represented in FIG. 9, but by heelpieces 37 between which is spread the resin defining the skin 13 opposite to the acoustic skin 9.
• FIG. 15 shows yet another variant in which only the edges of the face of the foam roll opposite the acoustic face define an interstice with the mold 7b, so that the skin 13 opposite to the acoustic skin 9 does not extend only on the periphery of the moss loaf 1.
• Figure 16 illustrates a. variant embodiment of the perforations in the acoustic skin of the panel according to the invention: in this variant, the pads 39 are integral with the rigid half-mold 7a, so as to define perforations in the acoustic skin 9 during the injection of resin inside the mold 7.
• the length of these studs .. is..studied. way. to penetrate sufficiently deep inside the foam forming the bread 1, taking into account the migration of the resin inside this foam cake.
• the orientation of the studs 39 is substantially parallel to the demolding direction D of the molding tool 7; in the particular case where the acoustic surface of the foam roll is curved, as shown in Figure 7, the section of these pads will be studied so that the perforations made in the acoustic skin 9 all have substantially the same section.
• a porous wall 1c may optionally be interposed between these different foam bars 1a, 1b.
• the manufacturing method of an acoustic attenuation panel according to the invention is particularly simple: contrary to the state of the art, it is not necessary to first make the acoustic skin.
• the foam roll can play the role of the molding tool, in particular acoustic skin, and it is therefore not necessary to provide a specific molding tool for carrying out this process. skin,.- ⁇
• the coating of fresh bread foam with a composite material allows for an intimate combination of these materials, and thus excellent cohesion of the whole.
• this piercing can indeed be performed later ( variant of the drapery or variant overmoulding), or at the same time (variant overmolding) as the polymerization of the acoustic skin.
• the foam bread offers a compressive strength that is clearly greater than that which a honeycomb structure can offer, which makes it possible to apply to this foam roll significantly higher pressures, especially when the evacuation step illustrated in Figure 5.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Composite Materials (AREA)
• Multimedia (AREA)
• Acoustics & Sound (AREA)
• Physics & Mathematics (AREA)
• Architecture (AREA)
• Civil Engineering (AREA)
• Structural Engineering (AREA)
• Casting Or Compression Moulding Of Plastics Or The Like (AREA)
• Soundproofing, Sound Blocking, And Sound Damping (AREA)
• Laminated Bodies (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

Country Status (8)

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• 2008
  • 2008-12-22 FR FR0807349A patent/FR2940176B1/fr not_active Expired - Fee Related
• 2009
  • 2009-08-26 CN CN2009801514809A patent/CN102256770A/zh active Pending
  • 2009-08-26 RU RU2011129699/05A patent/RU2519382C2/ru not_active IP Right Cessation
  • 2009-08-26 EP EP09737033A patent/EP2385894A1/fr not_active Withdrawn
  • 2009-08-26 US US13/141,333 patent/US20110254196A1/en not_active Abandoned
  • 2009-08-26 CA CA2743352A patent/CA2743352A1/fr not_active Abandoned
  • 2009-08-26 WO PCT/FR2009/001033 patent/WO2010072903A1/fr active Application Filing
  • 2009-08-26 BR BRPI0923268A patent/BRPI0923268A2/pt not_active IP Right Cessation

Non-Patent Citations (1)

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