WO2009050651A2 - Apparatus for the manufacture of structural elements made of composite material - Google Patents

Apparatus for the manufacture of structural elements made of composite material Download PDF

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Publication number
WO2009050651A2
WO2009050651A2 PCT/IB2008/054229 IB2008054229W WO2009050651A2 WO 2009050651 A2 WO2009050651 A2 WO 2009050651A2 IB 2008054229 W IB2008054229 W IB 2008054229W WO 2009050651 A2 WO2009050651 A2 WO 2009050651A2
Authority
WO
WIPO (PCT)
Prior art keywords
tool
forming surface
cover
forming
extends
Prior art date
Application number
PCT/IB2008/054229
Other languages
French (fr)
Other versions
WO2009050651A3 (en
Inventor
Francesco Beneventi
Vincenzo De Vita
Vincenzo Pelusi
Giovanni Antonio Iannantuoni
Original Assignee
Alenia Aeronautica S.P.A.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Alenia Aeronautica S.P.A. filed Critical Alenia Aeronautica S.P.A.
Publication of WO2009050651A2 publication Critical patent/WO2009050651A2/en
Publication of WO2009050651A3 publication Critical patent/WO2009050651A3/en

Links

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
    • B29C70/30—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
    • B29C70/342—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 using isostatic pressure
    • 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
    • B29K2707/00—Use of elements other than metals for preformed parts, e.g. for inserts
    • B29K2707/04—Carbon

Definitions

  • the present invention relates to an apparatus for the manufacture of structural elements made of composite material based on carbon fibre, for aircraft construction.
  • pregs the sheets
  • the sheets may be deposited already pre-impregnated with non-polymerized, thermosetting, synthetic resin which serves as binder.
  • the resin is infused after the sheets have been superimposed on the forming tool in the dry state.
  • preform which is constituted by the laminated fibre sheets with the addition of resin, is then covered by a vacuum bag to remove the air and introduced into an autoclave with the application of high temperature and pressure so as to bring about the polymerization of the thermosetting resin matrix and confer the desired shape on the laminated layers.
  • the invention has the dual objective of achieving an excellent final result in the polymerization or curing of composite structural elements, even if they are of considerable size, and of implementing the polymerization process efficiently, quickly and economically, without the use of an autoclave.
  • an apparatus comprises a forming tool 10 with an upper forming surface 11 on which the films C of a reinforcing fibre, typically carbon fibre, are deposited and superimposed, making up a preform.
  • the forming surface may of course adopt any form with various shapes, according to specific requirements.
  • one or more electrical heating resistors are incorporated in the forming tool, and are distributed appropriately so as to heat the forming surface 11 of the tool uniformly and in relatively short periods of time.
  • the tool is closed at the top by an openable or removable cover 13 which has a shape in plan that substantially matches that of the tool.
  • a sealing gasket 14 extends continuously at the interface between the cover and the tool, along the perimeter of the lower edge of the cover.
  • the gasket 14 is preferably engaged in a peripheral groove 15 which extends around the upper surface 11 of the forming tool.
  • At least one suction duct 16 extends through the tool 10 and opens in the forming surface 11 in order to withdraw the air from the carbon- fibre preform C after a vacuum bag V has been placed thereon. Depressurization is performed by means of a vacuum pump 17.
  • an inlet line 18 is provided for the supply of compressed air or other gas pressurized by a pump 19 associated with the apparatus.
  • the inlet line 18 preferably extends through the cover 13.
  • one or more resin-supply ducts 20 may also extend through the tool 10; these ducts open in the forming surface 11 in order to supply the thermosetting resin to the dry preform.
  • the heating of the resistors 12 is controlled by a processing unit, typically a PLC or programmable logic controller equipped with a personal computer, which supervises the operation of the apparatus as a whole and hence also the operation of the vacuum pump 17, of the pressurization pump 19, and of the resin infusion pump 21.
  • the resistors are controlled by the PLC in order to execute one or more tool-heating ramps, after which the carbon-fibre layers are deposited on the forming surface thereof (in the dry state or pre-impregnated with resin).
  • a vacuum bag constituted by a strong film of polymer material is then placed over the laminated layers, the vacuum pump 17 is activated, and the air is removed from the preform. If the preform is dry, the infusion of resin is activated by means of the pump 21. The space inside the cover is then pressurized and the resin is caused to polymerize at a predetermined temperature by supplying electric current to the resistors 12.
  • the PLC enables the basic quantities or parameters for the execution of a polymerization cycle, that is, the pressure, the heating and the vacuum, to be controlled better than in an autoclave.
  • the heating ramps and the pre-heating ramps can be executed with the cover open whilst manual activities are performed, for example, to reposition and adapt the carbon fibres to make them copy the shape of the tool exactly.
  • the apparatus permits working with some flexibility.
  • the resin can also be infused without pressurization, with the cover open and with the resistors switched on.
  • the resistors 12 can be arranged and distributed advantageously so as to ensure uniformity of temperature throughout the composite material. This eliminates a typical disadvantage of the processing of large composites in an autoclave in which temperature differences of more than 3 0 C between one point and another of the tool may give rise to manufacturing defects.

Abstract

Electrical resistors (12) are incorporated in a forming tool (10) having an upper forming surface (11) on which to deposit a superimposed arrangement of reinforcing- fibre sheets (C).A vacuum bag (V) is placed on the reinforcing-fibre sheets. An openable cover (13) is arranged on the tool to define a hermetically sealed space (22) therewith. A vacuum pump (16) withdraws air from the forming surface (11) and an inlet line (18) admits pressurized air to the space (22) through the cover (13). Optional resin-supply ducts (20) open in the forming surface (11).

Description

Apparatus for the manufacture of structural elements made of composite material based on carbon fibre, for aircraft construction
The present invention relates to an apparatus for the manufacture of structural elements made of composite material based on carbon fibre, for aircraft construction.
In the aircraft construction field, a process is used for the manufacture of structural elements such as, for example, beams, which comprises the lamination or deposition of carbon fibre sheets on a forming tool. In some cases, the sheets (known as "prepregs") may be deposited already pre-impregnated with non-polymerized, thermosetting, synthetic resin which serves as binder. Alternatively, the resin is infused after the sheets have been superimposed on the forming tool in the dry state. The so-called preform, which is constituted by the laminated fibre sheets with the addition of resin, is then covered by a vacuum bag to remove the air and introduced into an autoclave with the application of high temperature and pressure so as to bring about the polymerization of the thermosetting resin matrix and confer the desired shape on the laminated layers. In some cases, when sheets that have not been pre-impregnated are superimposed on the forming tool, a measured quantity of resin is provided in the vacuum bag; the resin permeates the fibre sheets and polymerizes in the autoclave. This latter technique is known in the field as "resin film infusion" or "resin transfer moulding" when a closed tool is used with the injection of resin for polymerization in the autoclave. The polymerization of long or wide structural elements requires an autoclave of large dimensions, which leads to high installation and running costs. The autoclaves generally require fairly expensive associated tooling for implementing the fairly slow working cycles.
The invention has the dual objective of achieving an excellent final result in the polymerization or curing of composite structural elements, even if they are of considerable size, and of implementing the polymerization process efficiently, quickly and economically, without the use of an autoclave.
According to the invention, this object is achieved by means of an apparatus having the features defined in the appended claims. A preferred embodiment of the invention will now be described, purely by way of non- limiting example, with reference to the sole appended drawing which is a schematic vertical section through an apparatus according to the invention.
With reference to the drawing, an apparatus according to the invention comprises a forming tool 10 with an upper forming surface 11 on which the films C of a reinforcing fibre, typically carbon fibre, are deposited and superimposed, making up a preform. The forming surface may of course adopt any form with various shapes, according to specific requirements.
According to an important feature of the invention, one or more electrical heating resistors, only schematically designated 12, are incorporated in the forming tool, and are distributed appropriately so as to heat the forming surface 11 of the tool uniformly and in relatively short periods of time.
The tool is closed at the top by an openable or removable cover 13 which has a shape in plan that substantially matches that of the tool. A sealing gasket 14 extends continuously at the interface between the cover and the tool, along the perimeter of the lower edge of the cover. The gasket 14 is preferably engaged in a peripheral groove 15 which extends around the upper surface 11 of the forming tool.
At least one suction duct 16 extends through the tool 10 and opens in the forming surface 11 in order to withdraw the air from the carbon- fibre preform C after a vacuum bag V has been placed thereon. Depressurization is performed by means of a vacuum pump 17.
In order to pressurize the enclosed space 22 between the cover and the tool, an inlet line 18 is provided for the supply of compressed air or other gas pressurized by a pump 19 associated with the apparatus. The inlet line 18 preferably extends through the cover 13.
Optionally, in order also to implement infusion processes, one or more resin-supply ducts 20 may also extend through the tool 10; these ducts open in the forming surface 11 in order to supply the thermosetting resin to the dry preform. The heating of the resistors 12 is controlled by a processing unit, typically a PLC or programmable logic controller equipped with a personal computer, which supervises the operation of the apparatus as a whole and hence also the operation of the vacuum pump 17, of the pressurization pump 19, and of the resin infusion pump 21.
The individual operations performed by the apparatus, as discussed briefly below, do not differ appreciably from the conventional operations and are therefore not described in detail in this specification.
In operative conditions, the resistors are controlled by the PLC in order to execute one or more tool-heating ramps, after which the carbon-fibre layers are deposited on the forming surface thereof (in the dry state or pre-impregnated with resin). A vacuum bag constituted by a strong film of polymer material is then placed over the laminated layers, the vacuum pump 17 is activated, and the air is removed from the preform. If the preform is dry, the infusion of resin is activated by means of the pump 21. The space inside the cover is then pressurized and the resin is caused to polymerize at a predetermined temperature by supplying electric current to the resistors 12.
The PLC enables the basic quantities or parameters for the execution of a polymerization cycle, that is, the pressure, the heating and the vacuum, to be controlled better than in an autoclave. The heating ramps and the pre-heating ramps (to soften the carbon fibres) can be executed with the cover open whilst manual activities are performed, for example, to reposition and adapt the carbon fibres to make them copy the shape of the tool exactly.
The apparatus permits working with some flexibility. For example, the resin can also be infused without pressurization, with the cover open and with the resistors switched on.
The resistors 12 can be arranged and distributed advantageously so as to ensure uniformity of temperature throughout the composite material. This eliminates a typical disadvantage of the processing of large composites in an autoclave in which temperature differences of more than 30C between one point and another of the tool may give rise to manufacturing defects.
Those skilled in the art will recognize that, whereas an autoclave takes 60 to 90 minutes to reach a temperature of 18O0C, with the invention this temperature can be reached in about 13 minutes with a considerable saving of energy and time. It will be appreciated that the heat is transmitted directly by conduction rather than, as in autoclaves, by convection by heating the air or nitrogen. Considerable thermal efficiency is thus achieved. Moreover, the apparatus can simultaneously serve several tools in parallel for the same curing cycle (star connection). Finally, it will be appreciated that the apparatus is transportable (for example, in an airport hanger) so that composite structures that may be damaged or defective can be repaired on the spot.
The invention is not intended to be limited to the embodiment described and illustrated herein, which should be considered as an example of the implementation of the apparatus; rather, the invention may undergo modifications relating to the shape, size and arrangement of parts and materials used.

Claims

1. Apparatus for the manufacture of structural elements made of composite fibre material for aircraft construction, comprising, in combination: - a forming tool (10) with an upper forming surface (11) on which to deposit a superimposed arrangement of reinforcing fibre sheets (C), heating means (12) incorporated in the forming tool (10) for controlling the temperature of the forming surface (11), an openable or removable cover (13) which is arranged on the forming tool (10) to define a closed space (22) therewith, hermetic sealing means (14) interposed between the cover (13) and the forming tool (10) for sealing the space (22) hermetically, depressurizing means (16) communicating with the upper forming surface of the tool, and - pressurizing means (18) for supplying pressurized air into said space.
2. Apparatus according to Claim 1, wherein the heating means (12) comprise electrical resistors which are distributed in the forming tool in a manner such as to heat the forming surface (11) of the tool (10) uniformly.
3. Apparatus according to Claim 1, wherein the depressurizing means include at least one suction duct (16) which extends through the tool (10) and opens in the forming surface (11).
4. Apparatus according to Claim 3, wherein the depressurizing means further comprise a vacuum pump (17) associated with the apparatus.
5. Apparatus according to Claim 1, wherein the pressurizing means comprise an inlet line (18) for the supply of compressed air or other gas pressurized by a pump (19) associated with the apparatus.
6. Apparatus according to Claim 5, wherein the inlet line (18) extends through the cover (13).
7. Apparatus according to Claim 1, further comprising means (20) for supplying a resin matrix.
8. Apparatus according to Claim 7, wherein the means for supplying the resin matrix comprise at least one supply duct (20) which extends through the tool (10) and opens in the forming surface (11).
9. Apparatus according to any one of the preceding claims, further comprising a programmable electronic unit (PLC) operatively connected to the heating means and to the depressurizing, pressurizing and resin-supply means.
10. Apparatus according to Claim 1, wherein the cover (13) has a shape in plan substantially matching that of the tool (10).
11. Apparatus according to Claim 10, wherein the sealing means (14) comprise a sealing gasket which extends continuously at the interface between the cover (13) and the tool (10).
12. Apparatus according to Claim 11, wherein the gasket (14) is fitted along the perimeter of a lower edge of the cover (13).
13. Apparatus according to Claim 11, wherein the gasket (14) engages in a peripheral groove (15) of the forming tool which extends around the forming surface (11).
PCT/IB2008/054229 2007-10-19 2008-10-15 Apparatus for the manufacture of structural elements made of composite material WO2009050651A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITTO2007A000741 2007-10-19
ITTO20070741 ITTO20070741A1 (en) 2007-10-19 2007-10-19 EQUIPMENT FOR THE MANUFACTURE OF STRUCTURAL ELEMENTS OF COMPOSITE MATERIAL BASED ON CARBON FIBER FOR THE CONSTRUCTION OF AIRCRAFT.

Publications (2)

Publication Number Publication Date
WO2009050651A2 true WO2009050651A2 (en) 2009-04-23
WO2009050651A3 WO2009050651A3 (en) 2009-06-25

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Application Number Title Priority Date Filing Date
PCT/IB2008/054229 WO2009050651A2 (en) 2007-10-19 2008-10-15 Apparatus for the manufacture of structural elements made of composite material

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WO (1) WO2009050651A2 (en)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9511519B2 (en) * 2014-02-04 2016-12-06 The Boeing Company System and method of vacuum bagging composite parts

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1181383A (en) * 1966-11-18 1970-02-18 Inst Schienenfahrzeuge Method of and apparatus for producing shock and sound-absorbing wheel bodies for high-speed rail vehicles
FR2673571A1 (en) * 1991-03-07 1992-09-11 Acb Method of manufacturing a laminate consisting of fibrous reinforcements which are impregnated with thermosetting resin
EP0659541A1 (en) * 1993-12-21 1995-06-28 AEROSPATIALE Société Nationale Industrielle Process and apparatus for manufacturing multilayered, low pressure impregnated articles particularly having deep undercuts
US5456874A (en) * 1991-07-13 1995-10-10 Saint Gobain Vitrage International Process for producing a glazing equipped with a peripheral frame based on a polymer
US6017484A (en) * 1997-01-21 2000-01-25 Harold P. Hale Method for manufacture of minimum porosity, wrinkle free composite parts
DE10150659A1 (en) * 2001-10-17 2003-05-08 Kraft Uwe Molding tool for production of thin walled fiber reinforced plastic products includes an edge clamping frame and/or cover plate and a pressurized flexible sheet for compression of impregnated fiber reinforcement
WO2007088495A1 (en) * 2006-01-31 2007-08-09 Selle Royal S.P.A. Process for making integral elastic supports, related mold and support obtained thereby

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1181383A (en) * 1966-11-18 1970-02-18 Inst Schienenfahrzeuge Method of and apparatus for producing shock and sound-absorbing wheel bodies for high-speed rail vehicles
FR2673571A1 (en) * 1991-03-07 1992-09-11 Acb Method of manufacturing a laminate consisting of fibrous reinforcements which are impregnated with thermosetting resin
US5456874A (en) * 1991-07-13 1995-10-10 Saint Gobain Vitrage International Process for producing a glazing equipped with a peripheral frame based on a polymer
EP0659541A1 (en) * 1993-12-21 1995-06-28 AEROSPATIALE Société Nationale Industrielle Process and apparatus for manufacturing multilayered, low pressure impregnated articles particularly having deep undercuts
US6017484A (en) * 1997-01-21 2000-01-25 Harold P. Hale Method for manufacture of minimum porosity, wrinkle free composite parts
DE10150659A1 (en) * 2001-10-17 2003-05-08 Kraft Uwe Molding tool for production of thin walled fiber reinforced plastic products includes an edge clamping frame and/or cover plate and a pressurized flexible sheet for compression of impregnated fiber reinforcement
WO2007088495A1 (en) * 2006-01-31 2007-08-09 Selle Royal S.P.A. Process for making integral elastic supports, related mold and support obtained thereby

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Publication number Publication date
WO2009050651A3 (en) 2009-06-25
ITTO20070741A1 (en) 2009-04-20

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