Classifications

• • 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
  • B29D99/0025—Producing blades or the like, e.g. blades for turbines, propellers, or wings
  • B29D99/0028—Producing blades or the like, e.g. blades for turbines, propellers, or wings hollow blades
• • 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
  • B29C37/00—Component parts, details, accessories or auxiliary operations, not covered by group B29C33/00 or B29C35/00
  • B29C37/006—Degassing moulding material or draining off gas during moulding
• • 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
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/32—Component parts, details or accessories; Auxiliary operations
  • B29C43/36—Moulds for making articles of definite length, i.e. discrete articles
  • B29C43/3642—Bags, bleeder sheets or cauls for isostatic pressing
• • 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
• • 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
  • B29D24/00—Producing articles with hollow walls
  • B29D24/002—Producing articles with hollow walls formed with structures, e.g. cores placed between two plates or sheets, e.g. partially filled
  • B29D24/008—Producing articles with hollow walls formed with structures, e.g. cores placed between two plates or sheets, e.g. partially filled the structure having hollow ridges, ribs or cores
• • 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
  • B29C43/00—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor
  • B29C43/02—Compression moulding, i.e. applying external pressure to flow the moulding material; Apparatus therefor of articles of definite length, i.e. discrete articles
  • B29C43/10—Isostatic pressing, i.e. using non-rigid pressure-exerting members against rigid parts or dies
  • B29C43/12—Isostatic pressing, i.e. using non-rigid pressure-exerting members against rigid parts or dies using bags surrounding the moulding material or using membranes contacting the moulding material

Definitions

• the present invention relates to a method for manufacturing hollow rigid structures produced from sheet material of fibers impregnated with resin, as well as to a device for carrying out the method. It also relates, as an industrial product, to the structures obtained according to the process.
• the invention can be the subject of various applications in various fields of industry, it has very particular advantages in aeronautics in particular for the constitution of structures of complex shapes which must combine perfect mechanical resistance with lightness as well. great as possible. This is the reason why the invention will be exposed by reasoning from structures used in aeronautics without this being a desire to limit the invention.
• rigid hollow structures such as aircraft wings for example, currently consist of an outer skin defining two walls spaced from one another and stiffened by a series of ribs and internal beams.
• This organization is characteristic of metal construction where the skins, ribs and beams are linked most of the time by riveting.
• the coverings, the ribs and the side members are made of fibers impregnated with resin, the structure remains the same and the riveting is replaced by bonding of the elements.
• This known process for producing rigid hollow structures made of resin-impregnated fibers is long to implement, requires numerous and delicate operations to be carried out as much as to control, sophisticated equipment (autoclave) and requires a very long manufacturing cycle qyi is not compatible with mass production.
• the present invention provides a new method for manufacturing rigid hollow structures which makes it possible to obtain a one-piece structure, produced in a single polymerization operation and entirely made of fiber materials impregnated with resin.
• the invention in its most general aspect, relates to a new process for the manufacture of hollow rigid structures produced from materials in sheets of fibers impregnated with polymerizable resins, characterized in that
• the plies of fibers are placed on the flexible envelope in such a way that the said plies can slide over one another.
• the flexible envelope is caused to expand until the layers of fibers come into contact with the walls of the mold and the resin is polymerized.
• the method according to invention is characterized in that:
• the mold is closed and, after heating, the flexible envelopes are caused to expand in order to press the sheets of fibers previously impregnated with resin against each other others and against the walls of the mold then which ensures the polymerization of the resin.
• the cooling of the part can be improved by ensuring the forced circulation of a cooling fluid either between the deformable envelope and the mandrel or preferably inside the mandrel itself.
• the device that is the subject of the invention therefore makes it possible, among other things, to significantly reduce the times necessary for temperature stabilization of the mold and cooling of the assembly to shorten the manufacturing cycles.
• the device for implementing the method is characterized in that it comprises at least one hollow rigid mandrel on which is threaded an elastically deformable envelope, a means for at least locally expanding the deformable envelope to separate it from the hollow mandrels , means for mounting and immobilizing the envelope mandrel assembly in a mold so that the periphery of the envelope is spaced from the walls of the mold before the expansion phase
• the invention relates, as a new industrial product, to a hollow rigid structure comprising a continuous peripheral surface forming the upper and lower faces of the cells extending over the entire length of the structure and of the partitions connecting the upper and lower faces over the entire length of the structure and separating the cells from each other, the said structure being produced in a single block from materials in layers of fibers impregnated with resin.
• - 1 simultaneous polymerization (or baking) of the outer skins of the structure and the internal stiffeners, which results in the elimination of any sticking and a reduction in the overall mass of the structure with equal mechanical characteristics.
• - 2 cortrôlable evacuation of air and resin contained in the sheets of fibers during the polymerization by acting on the inflation pressure of the deformable envelope which allows to obtain a product of the required quality.
• - 3 manufacture of rigid structures of great lengths with local resistances perfectly mastered and adapted to needs thanks to an internal distribution of stiffenings according to the profile cut and thanks to the possibility of modulating the thickness of the layers of fibers according to the locations.
• FIG. 1a shows schematically, with partial cutaway, an airplane wing structure produced according to known techniques
• FIG. 1b schematically shows a wing obtained by the method according to the invention
• FIG. 2 is a longitudinal section of a mandrel used to implement the method of the invention
• Figure 3 is a cross section of the mandrel of Figure 2;
• FIG. 4 shows a half mold being fitted with mandrels
• - Figure 5 is an elevational view of the closed mold
• FIGS. 8 to 8d show different configurations of structures which can be obtained according to the method of the invention.
• FIG. 1a the current conventional process for manufacturing a hollow structure such as an airplane wing consists in placing a series of perforated ribs N in the transverse direction of the wing, these ribs having the profile of the section of the wing and being spaced from each other and rigidly held together by the longitudinal P-beams. The whole is covered with a skin E which completely envelops ribs and beams.
• FIG. 1b shows in comparison the structure of a similar wing obtained according to the method of the invention and in which all the elements are made of fibers impregnated with resin forming a single block consisting of a surface skin S stiffened by internal walls I constituting a series of non-deformable related hollow boxes.
• a hollow mandrel 1 is used, the section of which may be any, but preferably has a polygonal shape which approaches the final shape of the Turkish structure as shown in FIG. 3 comprising two lateral faces 2, two sides 3 upper and lower and four inclined faces 4.
• the mandrel must be very rigid to withstand radial crushing forces during the pressurization and therefore, preferably, must be made of metal with internal reinforcing ribs 5 stiffening each face.
• the inner chamber 6 of the mandrel is obstructed at its end by cheeks 7. Inside the chamber 6 are provided ducts 8 of pressurized air inlet which are connected to orifices 9 formed in the wall of the mandrel.
• the pipes 8 pass through the cheeks 7 at the end of the mandrel and are connected on the one hand to a source of pressurized air not shown and on the other hand to a suction system not shown.
• the mandrel 1 is covered on its periphery with an envelope 10 or sheath made of elastically deformable flexible material, the ends of which are forcefully clamped (in a leaktight manner) between flanges 11 of the mandrel and sealing flanges 12 fixed on the mandrel.
• a sealed chamber 13 is thus provided between the mandrel and the sheath, a chamber into which the pipes 8 for the arrival of air flow under pressure, thereby ensuring the expansion of the envelope or its retraction at will.
• the pipe 14 provides the introduction of a heat fluid or a cooling fluid inside the chamber of the mandrel while the tube 15 ensures the evacuation of these fluids.
• the pipes 14 and 15 are selectively connected to sources of hot or cold fluids (water or gas for example) not shown
• the mold intended to receive a series of mandrels like that of FIG. 3 is shown in FIGS. 4 to 6.
• the lower part 16 of the mold has an imprint 17 on the lower face of the final structure to be obtained and the upper plate 18 has a imprint 19 of the upper face of the structure.
• the junction plane of the mold comprises a number of seats 20 in which are intended to rest the supports 13 of the mandrels which will therefore protrude from the mold.
• the mold also has passages for the pipe 8 for supplying pressurized fluid.
• An orifice 21 is also provided to create a slight depression inside the mold, this orifice being connected by a pipe 22 to a suction device not shown.
• the sheath 10 not being inflated, a series of fiber layers 23-24 is draped first of all on the mandrels 1 so that the layers can follow the expansion of the sheath 10.
• a series of fiber layers 23-24 is draped first of all on the mandrels 1 so that the layers can follow the expansion of the sheath 10.
• one or more plies 23 covering a little more than the upper half of the mandrel will be used alternately with one or more plies 24 covering a little more than the lower half of the mandrel so that the edges of the plies overlap, however allowing their relative free movement.
• the lower part 16 of the mold is prepared by covering the imprint 17 with one (or more) ply 25 then the mandrels coated with the fiber plies are placed in the mold.
• drains which can for example have the shape of a half cylinders as in the drawings comprise a hollow hollow core 28 and porous (for example pierced with a multitude of holes) coated with a sleeve 29 of fibrous material impregnated or not with resin.
• the purpose of this drain is to capture air bubbles and excess resin discharged from the mold holes where the fiber sheets are subjected to significant pressure during the polymerization.
• These drains are intended to remain embedded in the final structure by making an accessory reinforcement.
• the drains are placed in the mold before closing by inserting them into the housings 30 provided in the mold (see FIG. 4). It will be noted that these drains can possibly protrude horidu from the mold in order to connect them, to a suction device for create a slight aspiration and strengthen their drainage role. Note that it is possible to improve (for very precise parts) the relative prior positioning of the draped mandrels and the drains by exerting traction on the ends protruding from the mold of the mandrels and drains, whether the assembly is in a horizontal position or in a vertical position.
• the assembly begins to heat by circulating a hot fluid in the interior chamber of the mandrel through the pipes 14-15.
• the heating could advantageously be obtained by a series of electrical resistors (heating cords) 32 fixed to the wall of the mandrel in the space reserved between the latter and the deformable sheath 10 as shown in the figures. 6 and 3.
• the sheaths 10 are inflated by admitting the fluid under pressure through the pipes 8.
• the sheets of impregnated fibers are then pressed against each other, an inflation control being able to be provided to ensure spontaneous and correct placement of the tablecloths.
• the assembly is cooled from the inside of the beams by circulating a cooling fluid either through the pipes 8 or through the pipes 14-15.
• the sheaths 10 are deflated, the mold is opened and the mandrels are extracted from the final structure. It will be noted that the progressive inflation of the sheaths 10 ensures progressive contacting of the layers of excess fibers in the direction of the spaces occupied by the drains.
• the triangular cavities that remain between the plies of the boxes and the outer buckets are therefore filled with resin and the drain so that the external skin is supported even in this place which is not directly in contact with the fiber sheets of the boxes.
• the latter may be used to improve the mechanical characteristics of the structure in tension and / or in compression.
• sheaths 10 not having a constant thickness, it will be possible to modulate the shape or the section of the final product or to obtain a differentiated evolution of the pressures from one zone to another.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Chemical & Material Sciences (AREA)
• Composite Materials (AREA)
• Moulding By Coating Moulds (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=9294577

Family Applications (1)

Country Status (3)

Families Citing this family (23)

Family Cites Families (9)

• 1983
  • 1983-11-28 FR FR8318914A patent/FR2555501A1/fr active Pending
• 1984
  • 1984-11-22 EP EP19850900127 patent/EP0162097A1/de not_active Withdrawn
  • 1984-11-22 WO PCT/FR1984/000280 patent/WO1985002365A1/fr not_active Ceased

Non-Patent Citations (1)

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