U.S. patent application number 13/888607 was filed with the patent office on 2013-09-19 for method for reinforcing a fiber composite component and arrangement for producing a reinforced fiber composite component.
This patent application is currently assigned to Airbus Operations GmbH. The applicant listed for this patent is AIRBUS OPERATIONS GMBH. Invention is credited to Philipp Baisch, Carsten Barlag, Tobias Dorawa, Torben Jacob, Milan Reinhardt.
Application Number | 20130240126 13/888607 |
Document ID | / |
Family ID | 43385643 |
Filed Date | 2013-09-19 |
United States Patent
Application |
20130240126 |
Kind Code |
A1 |
Reinhardt; Milan ; et
al. |
September 19, 2013 |
METHOD FOR REINFORCING A FIBER COMPOSITE COMPONENT AND ARRANGEMENT
FOR PRODUCING A REINFORCED FIBER COMPOSITE COMPONENT
Abstract
A method and an arrangement for reinforcing a fibre composite
component for the aviation and aerospace industry, in which a
reinforcing element having a receiving region and a pressure
element adapted to the receiving region geometry. The pressure
element is inserted into the reinforcing element receiving region.
The reinforcing element and the inserted pressure element are
fastened relative to one another in a reproducible manner by a
reversible fastening device. The fastening device includes a first
fastening portion mounted on the pressure element and a second
fastening portion which can be mounted on the reinforcing element.
The reinforcing element, with the pressure element, is then applied
in a reproducible manner to the fibre composite component to be
reinforced, to form a moulding portion. The formed moulding portion
is cured to connect the reinforcing element to the fibre composite
component. The fastening device and the pressure element are then
removed from the fibre composite component.
Inventors: |
Reinhardt; Milan;
(Ratzeburg, DE) ; Dorawa; Tobias; (Hamburg,
DE) ; Baisch; Philipp; (Stade, DE) ; Jacob;
Torben; (Beckdorf, DE) ; Barlag; Carsten;
(Jever, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
AIRBUS OPERATIONS GMBH |
Hamburg |
|
DE |
|
|
Assignee: |
Airbus Operations GmbH
Hamburg
DE
|
Family ID: |
43385643 |
Appl. No.: |
13/888607 |
Filed: |
May 7, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13496692 |
May 23, 2012 |
|
|
|
13888607 |
|
|
|
|
Current U.S.
Class: |
156/182 |
Current CPC
Class: |
B29C 31/008 20130101;
B29C 70/543 20130101; B29C 33/76 20130101; B29C 65/562 20130101;
B29D 99/001 20130101 |
Class at
Publication: |
156/182 |
International
Class: |
B29C 65/56 20060101
B29C065/56 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 18, 2009 |
DE |
102009029575.5 |
Claims
1. A method for reinforcing a fibre composite component for the
aviation and aerospace industry, comprising the following steps:
providing a reinforcing element comprising a receiving region and a
pressure element adapted to the geometry of the receiving region;
inserting the pressure element into the receiving region of the
reinforcing element; fastening the reinforcing element and the
inserted pressure element relative to one another in a reproducible
manner by means of a reversible fastening device, the reversible
fastening device comprising at least a first fastening portion
mounted on the pressure element and at least a second fastening
portion which can be mounted on the reinforcing element; applying
the reinforcing element, together with the pressure element
fastened thereto, in a reproducible manner to the fibre composite
component to be reinforced, to form a moulding portion; curing the
formed moulding portion to connect the reinforcing element to the
fibre composite component; and removing the reversible fastening
device and the pressure element from the reinforced fibre composite
component.
2. The method of claim 1, wherein after the application of the
reinforcing element at least the second fastening portion of the
reversible fastening device is removed before the formed moulding
portion is cured.
3. The method of claim 1, wherein the second fastening portion of
the reversible fastening device is mounted on the outside of the
reinforcing element, the reinforcing element being arranged between
the first fastening portion and the second fastening portion of the
reversible fastening device.
4. The method of claim 1, wherein the reinforcing element and the
inserted pressure element are fastened relative to one another in a
reproducible manner by applying magnetic forces.
5. The method of claim 4, wherein magnetic forces are applied by
means of one or more of permanent magnetic elements and
electromagnets.
6. The method of claim 5, wherein the first fastening portion is
formed using at least one of a permanent magnetic element and an
electromagnet, and the second fastening portion is formed using a
ferromagnetic element.
7. The method of claim 1, wherein the reinforcing element and the
inserted pressure element are fastened relative to one another in a
reproducible manner by means of a reversible adhesive element which
is mounted between the pressure element and the reinforcing
element, the adhesive element comprising an insert layer which is
arranged between the first fastening portion and the second
fastening portion of the adhesive element and formed for assisting
removal of the adhesive element.
8. The method of claim 1, wherein the reinforcing element and the
inserted pressure element are fastened relative to one another in a
reproducible manner by means of a device for generating and
applying electrostatic charging of the fastening portions.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. Ser. No. 13/496,692
filed May 23, 2012 and claims the benefit of U.S. provisional
application No. 61/243,682, filed Sep. 18, 2009, and German patent
Application No 10 2009 029 575.5, filed Sep. 18, 2009 the entire
disclosures of which are herein incorporated by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a method for reinforcing a
fibre composite component, in particular for the aviation and
aerospace industry, and to an arrangement for producing a
reinforced fibre composite component of this type.
BACKGROUND OF THE INVENTION
[0003] Although applicable to any fibre composite components, the
present invention and the problem on which it is based will be
described in detail below with reference to planar
carbon-fibre-reinforced plastics material (CFRP) components (also
referred to as fibre composite components), for example skin shells
of an aircraft.
[0004] It is generally known to reinforce CFRP skin shells using
CFRP stringers, in order to withstand the high loads in the
aircraft region with as low an additional weight as possible. In
this case, various stringer types are used, for example T, .OMEGA.
or I stringers.
[0005] In the following, stringers having a hollow profile will be
considered, for example stringers having a cap profile, .OMEGA.
profile and the like. The term hollow profile relates to a stringer
profile, the inner faces of which, together with a portion of a
fibre composite component to be reinforced, form a cavity or
interior. Hereinafter this interior is referred to as a receiving
region.
[0006] This will be illustrated in FIG. 1 by way of a schematic
perspective view of a reinforced fibre composite component.
[0007] Two reinforcing elements 3 are applied to a fibre composite
component portion 2, for example a skin shell or a skin laminate of
an aircraft, of the reinforced fibre composite component 1. The
reinforcing elements 3 are configured as a hollow profile, in this
example as a cap profile or .OMEGA. stringer. They each comprise
two foot portions 13 which as a base form the connecting face to
the skin shell. The foot portions 13 are connected to a cover wall
10 via side walls 11 and 12, which in this case project upwards at
an angle, the cover wall 10 extending substantially parallel to the
foot portions 13. The inner faces of the cover wall 10, side wall
11 and 12 and the portion of the fibre composite component portion
2 which is located therebelow define the above-mentioned interior,
which is referred to as a receiving region 9. In this case, the
regions where the reinforcing elements 3 are mounted are each
characterised as a moulding portion 8. In this case, after
completed mounting on the fibre composite component portion 2, the
left-hand reinforcing element 3 is also provided with a pressure
element 4 which is inserted into the receiving portion 9.
[0008] When producing fibre composite components of this type from
fibre composite plastics materials, it is necessary during the
curing process to compact the composite of fibres and matrix
materials in order to avoid air inclusions and to be able to
achieve a particular fibre volumetric content in the cured skin
laminate.
[0009] Fibrous semi-finished products are to be understood to mean
woven fabrics, non-woven fabrics and fibre mats. These are provided
with a matrix, for example an epoxy resin, and then cured, for
example in an autoclave.
[0010] Owing to the mostly planar configuration of the fibre
composite components 1, this compaction of the fibrous
semi-finished products or fibres during the curing process is
generally effected by the use of differential pressure. For this
purpose, a vacuum construction is created, which is advantageously
produced by a plastics material film which at its edges is
hermetically bonded to the mould. The mould and the film thus form
a hermetically sealed space in which the fibrous semi-finished
product is enclosed. By removing the medium inside this
hermetically sealed space by suction, a relative overpressure is
achieved outside the vacuum construction, whereby the composite of
fibres and matrix can be pressed during the curing process.
Alternatively or in addition, the force for compacting the
fibre/resin composite can be increased by a pressure increase
outside the vacuum construction.
[0011] The production of fibre composite components requires a
certain pressure during the curing process in order to compact the
skin laminate. This pressure can be applied or transferred to the
component by various pressure elements. As mentioned above, a
pressure element of this type is shown by reference numeral 4 in
FIG. 1. In this case, the pressure element 4 is also required in
particular to exert pressure on the face of the skin laminate which
is covered by the reinforcing element 3, between the foot portions
13 of the reinforcing element 3, in order to compact this
portion.
[0012] It is often necessary to position and fasten the pressure
element in a precise manner relative to the semi-finished product
and the curing device. Where applicable, component parts must be
received, transported and positioned as a unit together with the
pressure elements, for example by means of a gripper. For this
purpose a fastening device is required which fastens component
parts and pressure elements to one another and which can be
released again at the latest at the end of the production process.
This relates to all types of fibre composite production methods, in
particular prepreg and dry fibre methods, as well as similar
production methods in which, for example, one or the two parts of
the component may consist of other materials, for example a light
metal. Particularly in the case of processes involving cap
profiles, the interior or receiving region must be equipped with a
pressure element in order to compact the inner walls and in
particular the skin laminate of the portion of the fibre composite
component which is located below the receiving portion 9 (FIG.
1).
[0013] Until now, the pressure elements have either been received,
transported and then positioned relative to one another separately
from the components to be pressurised, or a common integration of a
so-called subelement (fibre composite profile, reinforcing element)
and a pressure element takes place in the vacuum construction,
although this is only possible in the case of very small
components, when the subelement and pressure element can be clamped
together at their end faces, for example. For large and very long
component parts, this is only possible at considerable additional
cost. The separate integration of the pressure elements and
subelements of the fibre composite component during the curing
process results in positioning inaccuracies and therefore
geometrical differences of the subsequent component. The pressure
elements are at risk of being displaced during the process. In the
worst case, they may be clamped in the component and laminated
in.
[0014] Until now the pressure elements have therefore been
positioned and attached using gravity and friction and/or using
one- or two-sided adhesive tapes, using which said elements can be
fixed inside and/or in/on the curing device. This method leads to
the drawback that these elements can sometimes no longer be
released after curing, the pressure elements therefore having to
remain in the component after curing, possibly leading to rejection
of the component.
[0015] The following methods are also known:
[0016] 1) The first side of the subsequent fibre composite
component in the form of the fibrous semi-finished product is laid
in the curing device. The pressure element is positioned on said
side before the cap element (reinforcing element) is put on. A
drawback in this case is that the pressure element can be displaced
and/or clamped between the two parts of the component during the
curing process.
[0017] 2) The pressure element is laid in the cap profile and held
manually while the cap element is being positioned. However, this
is only possible if the dimensions of the component are small. This
method is not possible in the case of relatively large components,
since many people and coordinated action are required for this
purpose. In this case, the pressure element may fall out of the cap
element, and there may therefore be a risk of damage. A further
risk is that of the pressure element being clamped between the skin
laminate (first side of the subsequent fibre composite component)
and the second part (reinforcing element).
[0018] 3) When the component is configured with a large length and
a constant internal cross-section, it is possible to draw in the
pressure element after placing the cap element on the skin
laminate. However, this method can only be used if the lengths of
the component do not exceed particular lengths dependent on the
material of the pressure element. In this case, however, the cap
element must have a constant internal cross-section over the entire
length.
[0019] 4) The pressure element is attached to the skin laminate
using adhesive tapes. The pressure element can no longer be removed
in the case of relatively large lengths of the cap element, since
the bond between the pressure element and the component is
reinforced by the pressure differential.
[0020] 5) Attachment using an adhesive is not possible for all
types of pressure element, since these must have a surface which is
anti-adhesive with regard to the material of the matrix. Owing to
these surfaces, low-viscosity adhesives roll off, preventing the
application of adhesive.
[0021] 6) When hollow components are produced from fibre composite
materials comprising pre-impregnated fibres in the co-bonding
method, the pressure element can be attached or fastened with
positive locking by means of an adhesive film. For this purpose,
the pressure element is integrated into the cured component
(reinforcing element) and prevented from falling out by a
continuous adhesive film. However, this can only be used for a
previously cured component and fibre composite components made of
pre-impregnated fibres. In addition, the cured component has a
higher weight owing to the additional adhesive film.
[0022] DE 10 2007 061 431 A1 discloses a method for reinforcing a
fibre composite component, in which a reinforcing element is
received by a receiving portion of a vacuum mat and applied in a
sealing manner to a fibre composite component to be reinforced, to
form a moulding portion. The vacuum mat can also receive stringers
having a hollow profile, but then pressure elements are also
required since the vacuum mat is not adapted for interiors of the
stringers.
[0023] DE 10 2008 032 834 discloses a method for positioning a
tubular mould core in the receiving region of a reinforcing
element. Means for positioning the mould core in the receiving
region with positive locking and/or frictional engagement are
provided at the reinforcing element. The means for positioning the
mould core are provided, for example, as clip-shaped undercuts in
the transition region between the foot portions and the side walls
of the reinforcing element.
[0024] EP 2 159 039 discloses a method for producing composite
structures, the composite material being placed on a mould body for
shaping. For positioning the composite material, magnets are
provided in the mould body. Owing to the fact that the composite
material comprises fibres made of a magnetic material, the
composite material can be placed and fastened accurately on the
mould body.
SUMMARY OF THE INVENTION
[0025] In a method for reinforcing a fibre composite component for
the aviation and aerospace industry, a reinforcing element
comprising a receiving region and a pressure element adapted to the
geometry of the receiving region are provided. The pressure element
is inserted into the receiving region of the reinforcing element.
In this case, the reinforcing element and the inserted pressure
element are fastened relative to one another in a reproducible
manner by means of a reversible fastening device. The reversible
fastening device comprises at least a first fastening portion
mounted on the pressure element and at least a second fastening
portion which can be mounted on the reinforcing element. The
reinforcing element, together with the pressure element fastened
thereto, is then applied in a reproducible manner to the fibre
composite component to be reinforced, to form a moulding portion.
The moulding portion formed in this manner is cured to connect the
reinforcing element to the fibre composite component. The
reversible fastening device and the pressure element are then
removed from the reinforced fibre composite component.
[0026] An arrangement for producing a reinforced fibre composite
component for the aviation and aerospace industry is also provided.
The arrangement comprises the following:
[0027] a reinforcing element comprising a receiving region;
[0028] a pressure element adapted to the geometry of the receiving
region for inserting the pressure element into the receiving
region;
[0029] a reversible fastening device for fastening the reinforcing
element and the inserted pressure element relative to one another
in a reproducible manner, the reversible fastening device
comprising at least a first fastening portion mounted on the
pressure element and at least a second fastening portion which can
be mounted on the reinforcing element;
[0030] a transport device which comprises a support device for
receiving the reinforcing element and the pressure element inserted
in the receiving region of the reinforcing element, for applying
the reinforcing element, together with the pressure element
fastened thereto, in a reproducible manner to the fibre composite
component to be reinforced, to form a moulding portion;
[0031] a curing device for curing the formed moulding portion, to
connect the reinforcing element to the fibre composite component;
and
[0032] a removal device for removing the reversible fastening
device and the pressure element from the reinforced fibre composite
component.
[0033] The transport device is provided for transporting at least
the reinforcing element comprising the inserted, fastened pressure
element into a predetermined position relative to the fibre
composite component to be reinforced. The arrangement can also
include at least a support device for receiving at least a
reinforcing element and a pressure element. The curing device can
comprise a base plate which, together with the transport device,
can have centring means which correspond to one another for
positioning the reinforcing element in a reproducible manner
relative to the fibre composite component to be reinforced.
[0034] The present invention thus has the advantage over the
approaches mentioned at the outset of making it possible to fasten
in a reversible manner reinforcing elements and pressure elements
made of different materials, in particular in the case of large and
long components.
[0035] A basic idea of the invention consists in providing a
reversible fastening of a reinforcing element, in particular a cap
profile or hollow profile, and a pressure element in
three-dimensional space relative to one another by means of a
reversible fastening device, in particular having magnetic
functional elements.
[0036] In this case, the reinforcing element and pressure element
remain fastened during movement, including rotation and positioning
of this entire arrangement inside or on the component parts to be
cured or the curing device, and can be released again at the latest
at the end of the production process.
[0037] The following advantages are provided: [0038] Reliable
positioning of reinforcing element and pressure element [0039] Good
positioning accuracy [0040] Complex positioning and fastening units
are dispensed with [0041] It is possible to fasten the reinforcing
element and the pressure element in the case of large and long
components, in particular when the pressure elements are configured
as a film tube. It is not necessary to fasten the pressure element
from the edge. [0042] Large component lengths can be handled, in
particular mechanically. [0043] The fastening is reversible. [0044]
The fastening allows the combined operation of fastening the
pressure element inside the reinforcing element and at the same
time fastening the reinforcing element/pressure element system in
the curing device and/or rigging device. [0045] The method makes it
possible to fasten the pressure element in the reinforcing element
during the handling process, without this fastening leading to an
increase in the forces during the removal process. [0046]
Mechanical clamping is not necessary for fastening the pressure
element in the reinforcing element (contact with activated adherend
surface is avoided). [0047] No disadvantageous additional weight
arises, since all elements can be removed again after the curing
process.
[0048] The reversible fastening device can be removed, at least in
part, before the formed moulding portion is cured. This is
advantageous because, when generating a magnetic fastening force,
permanent magnets are not negatively influenced in terms of their
service life and field strength properties by the curing
temperatures, and also because a magnetic element mounted or a
fastening portion applied outside the reinforcing element does not
interfere with vacuum components to be applied for the curing
process.
[0049] In an embodiment, the fastening device is formed in such a
way that a fastening force is provided by a pair of magnets and/or
a combination of a permanent magnet or electromagnet and a
magnetisable ferromagnetic element (for example a metal). The
reinforcing element and the pressure element are each provided with
a magnet (permanent magnet or electromagnet) or an element made of
ferromagnetic material. The magnet or ferromagnetic element can, as
a first fastening portion, be located either on, inside the wall
thickness of the pressure element or completely inside the pressure
element. The corresponding counterpart thereto, a second fastening
portion, is located either on the opposite side of the reinforcing
element and/or in a support device of a positioning and transfer
unit, by means of which the reinforcing element and the pressure
element are received as a unit.
[0050] In an embodiment, the second fastening portion of the
reversible fastening device is mounted on the outside of the
reinforcing element, the reinforcing element being arranged between
the first fastening portion and the second fastening portion of the
reversible fastening device in this case.
[0051] If one of the fastening portions consists of a magnetic
assembly made of ferromagnetic material, this material can be used
in various configurations: [0052] as continuous tape [0053] as a
plurality of individual small plates (which can be interconnected
in various ways, for example by means of adhesive tape, integrally
cast in a chain/cable element, etc.) [0054] as a chain comprising
ferromagnetic members [0055] as one or more cables.
[0056] The following can be used as materials for this purpose:
[0057] ferromagnetic iron [0058] ferromagnetic steel [0059]
ferromagnetic spring steel (for flexible applications) [0060] the
magnet per se (permanent magnet or electromagnet).
[0061] The above-mentioned ferromagnetic elements can be attached
to the pressure element using adhesive or using adhesive tape. In
some applications it is sufficient to bring the respective
fastening portion into position and hold it there by means of
gravity, in order then to produce the fastening using the
corresponding fastening portion and subsequently transport the
entire unit and position it on the component to be reinforced.
[0062] The magnetic fastening portion can be located in the wall of
the pressure element, it being possible to achieve this for example
by welding, casting or embedding said portion in the wall material
of the pressure element.
[0063] Inside the pressure element, the respective fastening
portion can for example result from a bond on the inner wall of the
pressure element, optionally during the production of the pressure
element. In certain cases positioning is also possible by means of
gravity or the geometry of the pressure element of the respective
fastening portion.
[0064] Depending on the production process, the magnet or
ferromagnetic material (the fastening portion) can be removed
partially or completely after the reinforcing element has been
positioned and cured. The use of a combination of a magnet and a
ferromagnetic element is recommended. It is advantageous for this
process to be carried out using the ferromagnetic element on the
pressure element and the magnet on the reinforcing element, since
in many such cases the magnet can be removed again before the
curing process.
[0065] The magnet, as a second fastening portion, can also be
integrated in a housing comprising a handle and/or handling
supports. This support device formed in this manner can, by way of
suitable connection means, also cooperate with a transport device
or be a component thereof.
[0066] In an alternative embodiment, the reinforcing element and
the inserted pressure element are fastened relative to one another
in a reproducible manner by means of the fastening device using a
reversible adhesive element which is mounted between the pressure
element and the reinforcing element. When this reversible adhesive
element is removed, the adhesive adhering to the reinforcing
element is removed completely or at least mostly. Adhesive and
cohesive bonds are possible. The adhesive can also be liquid,
film-like (for example double-sided adhesive tape) or solid
(thermoplastic hot-melt adhesive). In this case, there is the
advantage over the prior art that the adhesive can be removed
substantially completely.
[0067] The adhesive can also be formed in such a way that it loses
its adhesive strength by the effect of particular process
parameters during and/or after the curing process, or that its
adhesive strength is reduced to such an extent that complete
removal is possible. These process parameters may be, for example,
particular temperatures, fluids at particular temperatures,
particular chemicals in fluid form.
[0068] It is also possible for the adhesive to be substantially
completely removable by simultaneous application of a tensile force
to the pressure element and application of a particular fluid in a
defined chemical composition.
[0069] In an alternative configuration, the reversible adhesive
element is provided as a double-sided adhesive tape comprising an
insert layer which can be influenced, for example by repelling
magnetic forces from outside the reinforcing element and/or
attracting magnetic forces from inside the pressure element, in
such a way that release or removal of the adhesive layer is
assisted by the active magnetic forces.
[0070] Electrostatic forces can also be applied to assist the
removal of the reversible adhesive element comprising adhesive from
the reinforcing element.
[0071] A hot-melt adhesive can be formed in such a way that upon
cooling after the curing process it has a low pot temperature at
which removal of the pressure element is readily possible.
[0072] In yet another alternative, the reinforcing element and the
inserted pressure element are fastened relative to one another in a
reproducible manner by means of the fastening device using a device
for generating and applying electrostatic charging of the fastening
portions. For this purpose, the fastening portions are made of an
electrostatically chargeable material. In a particularly
advantageous embodiment, the reinforcing element and the pressure
element themselves form the electrostatically chargeable fastening
portions. Charging can take place for example via the support
device once positioning of the reinforcing element and pressure
element is complete. The electrostatic forces then form the
fastening force which holds the reinforcing element and pressure
element together.
[0073] The support device can comprise the second fastening portion
in the form of an electromagnet.
[0074] Alternatively, the support device can also have electrical
connections for applying electrostatic charging of the fastening
portions, in such a way that charging can take place in an
automatic, mechanically controlled manner, the safety of operating
personnel being easy to maintain.
BRIEF DESCRIPTION OF THE DRAWINGS
[0075] The invention is described in detail below by way of
embodiments with reference to the accompanying figures of the
drawings, in which:
[0076] FIG. 1 is a schematic perspective view of a reinforced fibre
composite component;
[0077] FIG. 2 is a schematic perspective exploded view of a
reinforcing element comprising a first embodiment of a fastening
device;
[0078] FIG. 3a-b are schematic cross-sectional views of the
reinforcing element according to FIG. 2 comprising variations of
the fastening device;
[0079] FIG. 4 is a schematic plan view of the reinforcing element
according to FIG. 2 comprising a further variation of the fastening
device;
[0080] FIG. 5 is a schematic perspective exploded view of the
reinforcing element according to FIG. 2 comprising a second
embodiment of a fastening device;
[0081] FIG. 6 is a schematic cross-sectional view of the
reinforcing element according to FIG. 2 comprising a further
variation of the fastening device and a support device; and
[0082] FIG. 7 is a schematic cross-sectional view of an exemplary
arrangement according to the invention for producing a reinforced
fibre composite component.
[0083] In the figures, like reference numerals denote like or
functionally like parts, unless indicated otherwise.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0084] FIG. 1 has already been described above.
[0085] To produce the example shown in FIG. 1 of an integral fibre
composite component 1 of an outer skin made of composite materials
of an aircraft (not shown), which fibre composite component is
reinforced with reinforcing elements 3, which in this case comprise
cap profiles, the reinforcing elements 3 made of cured fibre
composite materials are adhesively bonded to a skin laminate (the
fibre composite component portion 2 in FIG. 1) made of uncured
fibres pre-impregnated with resin (prepreg).
[0086] The reinforcing elements 3 are firstly provided with
pressure elements 4. For this purpose, a schematic perspective
exploded view of a reinforcing element 3 comprising a first
embodiment of a fastening device 5 is shown in FIG. 2.
[0087] A reinforcing element 3 for reinforcing a fibre composite
component 1 (see FIG. 1) is configured as a hollow profile. In this
case, the reinforcing element 3 comprises a receiving region 9
which is located between the foot portions 13 and limited by side
walls 11 and 12 and a cover wall 10. In this case, the receiving
region 9 has a trapezium-shaped cross-section.
[0088] In this example, a pressure element 4 is formed of a tube
having a trapezium-shaped cross-section which is adapted to the
inner contour, that is to say the receiving region 9, of the
reinforcing element 3.
[0089] The pressure element 4 and the reinforcing element 3 are
fastened relative to one another via a reversible fastening device
5. This reversible fastening device 5 comprises a first fastening
portion 6 on the pressure element 4 and a second fastening portion
7 on the reinforcing element 3.
[0090] In this first embodiment of the fastening device 5, the
first fastening portion 6 of the fastening device 5 is a
ferromagnetic element 15. It is attached to the face of the
pressure element 4 which corresponds to the inner face of the cover
wall 10 of the reinforcing element 3. The ferromagnetic element 15,
which may for example be a continuous tape, is attached using a
suitable adhesive and/or adhesive strips. A covering element 16 in
the form of a covering film which facilitates removal of the
pressure element 4 after the curing process and at the same time
also protects the ferromagnetic element 15 from external
influences, for example materials of the reinforcing element 3, is
mounted over the ferromagnetic element 15. The covering element 16
may for example be an anti-adhesive film, for example a
fluoropolymer (PTFE, FEP, ETFE), whereby for example adhesive
bonding owing to contamination with the matrix (epoxy resin) of the
skin laminate (see FIG. 1) is avoided.
[0091] In this example, the second fastening portion 7 of the
fastening device 5 is a magnetic element 18, for example a
permanent magnet, which is arranged on the cover wall 10 of the
reinforcing element 3. In this case, the magnetic element 18
comprises inclines 19 in order to facilitate cooperation with a
handling device (described in detail below). Depending on the
length of the reinforcing element 3, the magnetic element 18 can be
adapted or consist of a plurality of individual magnetic elements
18 arranged in succession in the longitudinal direction of the
reinforcing element 3. These individual magnetic elements 18 may
for example be arranged in a suitable strip or an enclosure.
[0092] The pressure element 4 provided with the first fastening
portion 6 is then inserted into the receiving region 9 of the
reinforcing element 3 and positioned relative to the reinforcing
element 3, the desired position of the reinforcing element 3 and
pressure element 4 being fixed by the cooperation of the first
fastening portion 6 and the second fastening portion 7 in such a
way that the first fastening portion 6, as a magnetisable
ferromagnetic element 15, is attracted by the second fastening
portion 7, as a magnetic element 18 or permanent magnet. In this
case, the pressure element 4 connected to the first fastening
portion 6 is also attracted in the receiving region 9 of the
reinforcing element 3 and held therein.
[0093] FIGS. 3a and 3b are schematic cross-sectional views of the
reinforcing element 3 according to FIG. 2 comprising variations of
the fastening device 5. In each case, the pressure element 4 is
inserted in the receiving region 9 of the reinforcing element 3 and
held fastened by the fastening device 5.
[0094] In FIG. 3a, the first fastening portion 6, namely the
ferromagnetic element 15, is mounted on the upper outer face of the
side of the pressure element 4 which corresponds to the inner face
of the cover wall 10 of the reinforcing element 3. In this
variation, the covering element 16 is arranged over the
ferromagnetic element 15, resting against the side faces of the
pressure element 4. In this case, the covering element 16 is
configured as a carrier film, as described in the case of FIG. 2,
the side thereof facing the pressure element 4 being coated with an
adhesive which forms bonds with the ferromagnetic element 15 on the
one hand and with the pressure element 4 on the other hand and thus
interconnects the ferromagnetic element 15 and pressure element
4.
[0095] A further variation of the fastening device 5 is shown in
FIG. 3b. In this case, the first fastening portion 6, namely the
ferromagnetic element 15, is located inside the pressure element 4.
The pressure element 4 may for example be the above-described tube.
In this case, the first fastening portion 6 is mounted inside the
pressure element 4, for example by bonding the first fastening
portion 6 to the inner face of the side of the pressure element 4
which corresponds to the inner face of the cover wall 10 of the
reinforcing element 3 and in this case contacts said face directly
with positive locking. Since in this example the first fastening
portion 6 is located inside the pressure element 4, it is covered
by the pressure element itself and protected from external
influences. In this example shown in FIG. 3b, the following
procedure can for example be adopted.
[0096] The reinforcing element 3 is arranged in such a way that the
receiving region 9 is upwardly open. The pressure element 4 can
then be inserted therein. The first fastening portion 6 is then
inserted into the interior of the pressure element 4, the first
fastening portion 6 being arranged by means of gravity on the inner
face of the side of the pressure element 4 which corresponds to the
inner face of the cover wall 10 of the reinforcing element 3. The
first fastening portion 6 is fastened by the subsequently mounted
second fastening portion 7 as described above and the pressure
element 4 is held in the previously arranged desired position
relative to the reinforcing element 3. The first fastening portion
6 is thus connected to the pressure element 4 with non-positive
locking via the fastening device 5, it being possible to dispense
with a bonded joint, for example.
[0097] FIGS. 3a and 3b show clearly for these examples (also
according to FIG. 2) that the first fastening portion 6 is mounted
on the pressure element 4 and the second fastening portion 7 is
mounted on the reinforcing element 3, the reinforcing element 3
being arranged between the first fastening portion 6 and the second
fastening portion 7. In this case, the second fastening portion 7
is arranged on the side of the reinforcing element 3 opposite the
pressure element 4. The fastening device 5 thus fastens the
pressure element 4 and the reinforcing element 3 with non-positive
locking in that the pressure element 4 and the reinforcing element
3 are pulled towards one another.
[0098] FIG. 4 shows a schematic plan view of the reinforcing
element 3 according to FIG. 2 comprising a further variation of the
fastening device 5. In this case, the second fastening portion 7 is
formed using a plurality of magnetic elements 18 (in this case in
the form of small, circular magnetic plates) which can for example
be interlinked in the longitudinal direction of the reinforcing
element 3.
[0099] FIG. 4 also shows the covering element 16, which in this
case, as in FIG. 3a, covers the ferromagnetic element 15 and is
attached as an adhesive film to the pressure element 4.
[0100] The fastening device 5 is formed so as to be reversible. For
the embodiments shown thus far, this means that in this case the
second fastening portion 7 can be mounted on the reinforcing
element 3 in a reversible manner, even in relatively large numbers.
For example, it can be connected to a suitable handle and can thus
be mounted and removed, as described in further detail below in
connection with FIG. 6.
[0101] FIG. 5 shows a second embodiment of a reversible fastening
device 5 in a schematic perspective exploded view of the
reinforcing element 3 according to FIG. 2. In this case, the
pressure element 4 and the reinforcing element 3 are connected via
a fastening device 5 comprising a reversible adhesive element 17.
In this case, the first fastening portion 6 can be mounted on the
pressure element 4 by adhesive bonding and the second fastening
portion 7 can also be mounted by adhesive bonding on the
reinforcing element 3, in this case on the inner face of the cover
wall 10. The adhesive layer of the second fastening portion 7 is
formed in such a way that it can be separated particularly easily
after the fibre composite component 1 has been cured. This can also
be done by applying particular process parameters, for example
different thermal effects, fluids, chemical substances and the
like.
[0102] In the example shown in this case, the reversible adhesive
element 17 comprises an insert layer 29 which is integrated therein
and made of a material which can be influenced by external forces,
for example magnetic forces and/or electrostatic forces, to assist
the removal of the adhesive tape 17 by repulsion and/or attraction.
For example, an electromagnet inserted from inside the pressure
element 4 can pull the insert layer 29 away from the reinforcing
element 3. The application of electrostatic charges of like or
different polarities (or the application of a corresponding
electrode) to the reinforcing element 3 and insert layer 29 are
mentioned by way of example.
[0103] It is also conceivable for the reversible adhesive element
17 to be an adhesive and/or cohesive compound, said compound being
liquid or film-like (for example adhesive tape). The reversible
adhesive element 17 can also comprise a thermoplastic hot-melt
adhesive, said adhesive remaining soft after the completed curing
operation upon cooling to a particular "pot temperature", and thus
allowing easy removal of the pressure element 4.
[0104] FIG. 6 is a schematic cross-sectional view of the
reinforcing element 3 according to FIG. 2 comprising a further
variation of the fastening device 5 and a support device 20.
[0105] In this example, the pressure element 4 is formed in such a
way that the first fastening portion 6 is inserted, for example
introduced and adhesively bonded, injection-moulded, welded or the
like, inside the wall of the pressure element 4. The second
fastening portion 7 is arranged as a magnetic element 18 in a
support body 21 of a support device 20, which in this case is
connected to a support element 22. The support element 22 may for
example be a cable loop or a rod comprising a handle for manual
handling. If the pressure element 4 is inserted in the receiving
region 9 of the reinforcing element 3 and positioned relative to
the reinforcing element 3, the second fastening portion 7 can be
mounted, in this example externally, on the reinforcing element 3
using the support device 20. The reinforcing element 3 can then be
transported together with the pressure element 4 which is fastened
and held relative to the reinforcing element 3 via the fastening
device 5.
[0106] The support device 20 can comprise a plurality of support
devices 20 distributed over the length of the reinforcing element
3. A support body 21 having the same length as the reinforcing
element 3 is also possible. For this purpose, the associated
support device 20 can be formed for one or more reinforcing
elements 3 and provided for mechanical transportation.
[0107] FIG. 7 is a schematic cross-sectional view of an example of
an arrangement 25 according to the invention for producing a
reinforced fibre composite component 1.
[0108] The skin laminate in the form of the fibre composite
component portion 2 (see FIG. 1) made of pre-impregnated fibres is
mounted on a base plate 27. In this case, two reinforcing elements
3, each comprising pressure elements 4 held by a reversible
fastening device 5, are for example each held on a transport device
25 via a support device 20, as described with reference to FIG. 6,
positioned on the fibre composite component portion 2 and applied.
The undersides of the foot portions 13 were prepared beforehand by
applying epoxy adhesive film.
[0109] With their side walls 11 and 12, the cover wall 10 and the
portion of the skin laminate covered thereby, the reinforcing
elements 3 applied to and positioned on the fibre composite
component portion 2 form an interior in which the pressure element
4 is arranged. In this state, the pressure element 4 is surrounded
by the inner faces of the walls 10, 11 and 12 of the reinforcing
element 3 and by the face of the fibre composite component portion
2 which is located therebelow.
[0110] In the support bodies 21, the two fastening portions 7 are
formed as electromagnets 23 and can each be loaded via a line 24
with electrical energy for magnetisation.
[0111] The arrangement 25 may for example be constructed in a
modular manner, in such a way that it can easily be adapted to
fibre composite components 1 of different dimensions.
[0112] The support devices 20 engage the reinforcing elements 3
provided with the pressure elements 4, in that the support bodies
21 are mounted on the outsides of the cover walls 10 of the
reinforcing elements 3. The electromagnets 23 are then supplied
with current and, together with the first fastening portions 6 of
the pressure elements 4, form reversible fastening devices. The
reinforcing elements 3 and pressure element 4 fastened relative to
one another in this way are transported onto the base plate 27
shown here in FIG. 7, positioned thereon and applied thereto. This
can be done in different ways depending on the situation, for
example by means of a crane device or using a rail system.
[0113] In this case, for reproducible positioning, the base plate
27 and transport device 26 at the edge of this component device
have centring means 28, for example centring pins on the transport
device 26 and corresponding recesses in the base plate 27.
[0114] If the reinforcing elements 3 comprising the pressure
elements 4 are centred, positioned and deposited on the base plate
27 by the transport device 26, the current supplied to the
electromagnets 23 is interrupted, it being possible for the second
fastening portions 7 in the form of the electromagnets 23 to be
removed by the transport device 26. However, the positioning
carried out beforehand between the pressure elements 4 and
reinforcing elements 3 remains.
[0115] The fibre composite component 1, together with the
reinforcing elements 3 and pressure elements 4 arranged therein,
which are loaded with corresponding pressure, can now be prepared
for curing and cured in a known manner. The pressure elements 4 are
then withdrawn from the reinforcing elements 3 after removal of the
pressurisation.
[0116] The arrangement 25 can comprise a control device which is
connected to the centring means 28, drive means for moving the
transport device 25, drive means for support devices 20, current
supply means for the electromagnets 23 and further signalling and
sensor devices. As a result, the production of the reinforced fibre
composite component 1 is automated in such a way that a high level
of reproducibility is achieved with the lowest likelihood of
errors, the pressure elements 4 and the support devices 20, and
thus also the reversible fastening devices 5, being reusable.
[0117] Although the present invention has been described herein by
way of preferred embodiments, it is not limited thereto but can be
modified in a variety of ways.
[0118] For example, not only .OMEGA. stringers but also reinforcing
elements having other hollow profile cross-sections, for example
triangular, square or polygonal, can be treated and processed using
the invention.
[0119] The fastening device 5 can also comprise first and second
fastening portions 6, 7 on the other side faces of the pressure
element 4 and the corresponding faces of the reinforcing element
3.
[0120] It is also conceivable for the fastening device 5 to
comprise a device for applying static electricity to corresponding
electrostatically chargeable fastening portions 6, 7. In this case,
the pressure element 4 and reinforcing element 3 themselves form
the fastening portions 6, 7. This is possible for example when
fastening portions 6, 7 or a pressure element 4 and reinforcing
element 3 consist of plastics material or other electrostatically
chargeable materials.
[0121] It is also possible for the first fastening portion 6 in the
pressure element 4 to be an electromagnet.
[0122] The reinforcing element 3 can also be partially cured.
[0123] A method for reinforcing a fibre composite component 1 for
the aviation and aerospace industry comprises the following method
steps:
[0124] A reinforcing element 3 comprising a receiving region 9 and
a pressure element 4 adapted to the geometry of the receiving
region 9 are provided. The pressure element 4 is inserted into the
receiving region 9 of the reinforcing element 3. In this case, the
reinforcing element 3 and the inserted pressure element 4 are
fastened relative to one another in a reproducible manner by means
of a reversible fastening device 5. The reversible fastening device
5 comprises at least a first fastening portion 6 mounted on the
pressure element 4 and at least a second fastening portion 7
mounted on the reinforcing element 3. The reinforcing element 3,
together with the pressure element 4 fastened thereto, is then
applied in a reproducible manner to the fibre composite component 1
to be reinforced, to form a moulding portion 8. The moulding
portion 8 formed in this manner is cured to connect the reinforcing
element 3 to the fibre composite component 1. The reversible
fastening device 5 and the pressure element 4 are then removed from
the reinforced fibre composite component 1.
[0125] In an exemplary embodiment of the method, the first
fastening portion 6 is formed by the pressure element 4 and the
second fastening portion 7 is formed by the reinforcing element
3.
[0126] In an exemplary embodiment of the arrangement 25, the
reversible fastening device 5 is formed for electrostatic charging
of the fastening portions 6, 7, the fastening portions 6, 7 being
formed as separate components or by the reinforcing element 3 and
the pressure element 4 respectively.
[0127] As is apparent from the foregoing specification, the
invention is susceptible of being embodied with various alterations
and modifications which may differ particularly from those that
have been described in the preceding specification and description.
It should be understood that I wish to embody within the scope of
the patent warranted hereon all such modifications as reasonably
and properly come within the scope of my contribution to the
art.
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