EP2424716A2

EP2424716A2 - Method for producing a fiber composite component for air and space technology

Info

Publication number: EP2424716A2
Application number: EP10714331A
Authority: EP
Inventors: Christian Nitsch
Original assignee: Airbus Operations GmbH
Current assignee: Airbus Operations GmbH
Priority date: 2009-04-28
Filing date: 2010-04-23
Publication date: 2012-03-07
Also published as: US8889050B2; DE102009002697A1; RU2492046C2; WO2010125001A4; JP2012525279A; CN102458790B; CN102458790A; US20120097323A1; WO2010125001A2; CA2760287A1; WO2010125001A3; RU2011143580A; DE102009002697B4

Abstract

The invention relates to a method for producing a fiber composite component (10), particularly for air and space technology, including the following method steps: forming a mold core (7) from a material containing cork using a core tool (14) for determining an outer geometry of the mold core (7); arranging the mold core thus formed to be attached to an at least partially hardened stiffening element (1) on a basic component (11) of the fiber composite component (10) to be produced for molding at least one mold segment (13) of the fiber composite component (10) to be produced; and multi-step charging at least the mold segment (13) with heat and/or pressure for producing the fiber composite component (10); and furthermore, a mold core (7) and a fiber composite component (10).

Description

Method for producing a fiber composite component for aerospace applications

The present invention relates to a method for producing a fiber composite component, in particular for aerospace, on a mandrel for producing such a fiber composite component and on a fiber composite component with at least one stiffening element, which produced by means of such a mandrel and / or such a method is.

Although applicable to any fiber composite components, the present invention and the problems underlying it are explained in more detail below with reference to planar carbon fiber reinforced plastic (CFRP) components, such as fuselage shells of an aircraft, stiffened with stiffening elements, which are also referred to as stringers ,

It is generally known to stiffen CFRP skin shells with CFRP stringers in order to withstand the high loads in the aircraft sector with the lowest possible weight. Essentially, two types of stringers are distinguished: T and Ω stringer.

The cross section of T-stringers is composed of the foot and the bridge. The foot forms the connecting surface to the skin shell. The use of T-Stringer stiffened skin shells is widely used in aircraft construction.

Ω stringer have approximately a hat profile, with its feet connected to the skin shell. Ω Stringer can be glued either on the hardened or uncured shell in the hardened or uncured state, or cured simultaneously with the shell wet-on-wet. Essentially, three different joining methods are distinguished:

1. Secondary bonding: hard / hard bonding with adhesive film

2. Co-bonding:

Hard / wet bonding optionally with adhesive film

3. Co-Curing:

Wet / wet bonding Even intermediate states, such as partially hardened, are possible. However, support or forming cores are necessary for the production of uncured or hardened skin shells stiffened with hardened and / or uncured Ω-stringers. On the one hand, the support or mold core has the function of fixing and supporting the uncooked semi-finished fiber products of the skin shell located underneath the cavity of the hardened stringer and / or the form-labile semi-finished fiber products of the stringer in the desired Ω-shape during the production process. On the other hand, in the case of co-bonding or in the co-curing process, the support core transmits the required autoclave pressure to the uncured joining partner.

So far, it is envisaged to use for example in an autoclave process for bonding the cured Ω stringer with the uncured skin as a support core profiled film tubes made of polyamide (PA) or fluoropolymer (FEP) or hollow profiles of silicone rubber. The autoclave pressure acts on the inside of the film tube or the silicone profile, which in turn transfer the autoclave pressure to the unheated skin laminate under the Ω-stringer. After the hardening process, the support cores are removed again.

The support core materials investigated so far do not always lead to a reproducibly good component quality. The required inner contour can not always be generated. So-called "tube bursters" lead to porous laminates or to insufficient adhesive joints and thus to elaborate rework or rejects.

There is also the problem in the production of Ω-stringers stiffened skin shells that the materials currently used for the core are costly (especially hollow rubber silicone rubber because of short life and possible damage) and after forming the Ω -Stringer difficult to be removed (eg because of foil inclusions), so that the material remaining in the stringers to the total weight of the aircraft contributes adversely. Furthermore, accumulation of pores and fiber deflections in the dermal field may result, which may adversely affect the uniformity, strength and force distribution in the dermal field structure.

For acoustic noise damping, it is known to apply a composite of CFRP and rubber to the skin fields between the stringers.

Against this background, the present invention seeks to provide a cheaper and lighter fiber composite component, in particular for aerospace.

According to the invention, this object is achieved by a method having the features of patent claim 1 and / or 4, a mold core having the features of patent claim 12 and / or by a fiber composite component having the features of patent claim 14.

Accordingly, a method for producing a fiber composite component, in particular for the aerospace industry, with the following method steps is provided: First, a mandrel made of cork material is formed with a core tool for defining an outer geometry of the mandrel. This shape created in this way - A -

The core is then arranged in contact with an at least partially hardened stiffening element on a base component of the fiber composite component to be produced for shaping at least one shaped section of the fiber composite component to be produced. A multi-stage loading at least of the mold section with heat and / or pressure takes place for producing the fiber composite component.

In a further method for producing a fiber composite component, in particular for aerospace, a mandrel made of cork material is formed with a core tool for defining an outer geometry of the mandrel, said mandrel then angeord on a base member of the fiber composite component to be produced - net becomes. On this at least in sections, at least one semifinished fiber product is then deposited for the shaping of at least one molding section of the fiber composite component to be produced. This is followed by a multi-stage loading at least of the mold section with heat and / or pressure to take place for producing the fiber composite component.

Furthermore, a mold core for producing a fiber composite component, in particular a stiffening element, for example a stringer, is provided on a base part, with a core material having cork.

Furthermore, a fiber composite component with at least one stiffening element, in particular for aerospace, which is produced by means of the mandrel according to the invention and / or the inventive method is provided.

One of the ideas underlying the present invention is that the mandrel is formed of cork-containing material.

Thus, the present invention over the approaches mentioned above has the advantage that the fiber composite Part can be produced by means of a cheaper mold core. The mandrel may also have multiple functions.

The stiffening element may have a cavity and, for example, be an Ω-stringer. But also cavities with other cross sections, such as trapezoidal, triangular, annular, wavy and the like., Are possible. Also stiffening elements without a cavity, such as T-stringer, U-stringer, L-stringer, by means of the mold core in function as a support core, for example, laterally supported. The mandrel is then partially attached to each of these geometries, e.g. as an outer support core, or completely, e.g. as inner support core, adapted and has the respective cross-sectional shape.

First, the mold core can be applied in contact with a cured or partially cured stiffening element with this on an uncured, partially cured or hardened base member as a support core of the stiffening element.

Furthermore, the mold core can be arranged on a base component and be used for producing a stiffening element on an uncured, partially cured or hardened base component, by laying semi-finished fiber products for the stiffening element to be created on the mold core.

In a function as a pure support core, it is removed after Autoklavhärtung the fiber composite component of the stiffening element and / or removed from this. The support core is dimensionally stable and at the same time elastic, which leads to a good

Quality of the fiber composite component leads. In addition, it is reusable and thus reduces costs. Its relatively low weight makes it easy to handle. He is also recyclable.

In another function, the mandrel remains as a so-called "flying support core" in and / or on the stiffening element Advantages of the advantage of acoustic noise insulation, which can be at least partially dispensed with additional sound insulation with conventional material. A fiber composite component in the form of a fuselage shell has an improved impact behavior and improved burn-through behavior (can also be increased by additions of flame retardants) by remaining supporting cores made of cork in and / or on the stiffening elements. In addition, such a, at least in part, thermal insulation is possible.

In the dependent claims are advantageous embodiments and improvements of the present invention.

In the case where the stiffening element is at least partially cured, i. H. precured or cured, the mold core can be provided with at least one fixing element for fixing the mold core to the stiffening element. In particular, when the mold core remains in the component, this fixation can be carried out, for example, in the form of adhesive tapes and / or resin films and / or adhesive films which are applied locally and / or continuously.

If the mandrel is to be removed again, it is preferred that the at least one fixing element is attached to the mandrel and interacts with at least one fixation element removably attachable to the reinforcing element, wherein, for example, the at least one fixing element and the at least one fixing auxiliary element are formed with magnetic strips. In this case, for example, the mandrel on one or more side surfaces, the

Appendix are provided on the stiffening element, be equipped with a magnetic strip. This magnetic strip can be glued and / or inserted into a corresponding (eg milled or molded) groove or recess. This groove or recess corresponds to the geometric cross section of the magnetic strip. This results in the advantage of a simple insertion of the magnetic strip and a residue-free fixation. In the case of thin-walled mandrels, a local thickening may take place in the region of the attachment or insertion of the magnetic strip. The stiffening element is then provided on the corresponding side / surface with a removable metal strip, eg a metal strip, which cooperates with the magnetic strip. The metal strip as fixation aid may also be a magnetic strip. It is advantageous that even this fixing aid is easy to apply and easy to remove.

According to a preferred embodiment of the invention, reinforcing means are arranged in the region of sharp transitions of the outer geometry of the mandrel to be formed. These reinforcing means, in particular Eckprofil- parts, have the advantage that they form the sharp edges and corners, wherein the mandrel can be provided in this area with easy-to-produce fillets.

Preferably, a release layer is applied to or applied to the mold core, which prevents adhesion of the material of the stiffening element or of the semi-finished fiber product and / or a matrix to the mold core. The release layer can be generated directly, for example, by machining operations by means of grinding and / or polishing. However, the release layer may also consist of a release film and / or of a liquid release agent and be additionally applied. This facilitates removal of the mold core after at least partial curing of the section of the fiber composite component created by means of the mold core.

Fiber semi-finished products are fabrics, scrims and fiber mats. These are provided with a matrix, for example an epoxy resin, and then cured, for example, in an autoclave. Hand lamination, prepreg, transfer molding and / or vacuum infusion processes, also in conjunction with winding technology, can be used for this purpose.

According to a further preferred development of the invention, the mandrel is arranged on a base part of semi-finished fiber composite products and / or at least partially surrounded by semifinished fiber products for forming at least one molding section of the fiber composite component. Thus, it is advantageous to form base parts, for example, skin shells, pressure cups, etc., with Ω strippers, but also other stiffening elements. Alternatively or additionally, it is also possible to produce separate fiber composite components that are completely defined in their shape by the mandrel.

The mold core, after curing, for example in the production of an Ω-stringer, can be pulled out of it in the longitudinal direction of the stringer, which is facilitated by the separating layer. Damage to the mold core is prevented by forming the mold core with at least one stiffening layer, for example made of tear-resistant fabric and / or with a tear-resistant release film.

According to a preferred embodiment of the invention, the mandrel is formed with at least one undercut. This undercut is preferably in the longitudinal direction of the mandrel. Thus, stringer can be produced by means of such a mandrel with variable cross section in the longitudinal direction.

The mandrel may be formed by a pressing process. In this case, cork flour, for example, is mixed with a binder and filler of, for example, rubber granulate and pressed to the desired shape of the mandrel by means of a forming tool. It is also possible that a mold core thus produced by means of abrading operations to a final dimension is brought, such as by cutting, grinding and polishing.

The mold core can also be composed of at least two core segments, for example two segments produced by pressing or else by other means, the segments being glued together. Of course, they can also be finished later.

The mandrel may also be formed as a hollow core with a core interior. In this case, side walls can be assembled from individual plates to the final shape. It is also possible that the mandrel is pressed, wherein the interior is filled with a corresponding core.

In another embodiment, the formation of the mold core as a hollow core having a core interior comprises the following sub-steps: Provision of a solid profile, which is produced for example in a pressing process. It is the outer and inner contour of the mandrel produced for example by means of milling and / or cutting tools. The outer geometry of the milling and / or cutting tool for forming the core interior corresponds to the geometric cross section of the core interior. The rotating milling and / or cutting tool is moved in the longitudinal direction of the solid profile in selbigem, wherein at the same time a longitudinal gap is introduced into the top wall of the mold core thus produced by the shank of the milling and / or cutting tool. This gap can be closed, for example, either with a glued strip of cork-containing material and / or with a fixing element with magnetic strip.

In yet another embodiment, the formation of the mandrel has the following sub-steps: provision of plate goods, for example by calendering or others

Pressing method is produced. It then blanks are cut, folded with a folding tool and then be connected by means of the core tool. The core tool serves as an external form. In an interior, another core can be introduced, this core can serve as a kind of Aufwickelkern when folding the plate goods. For folding, the plate product can be appropriately pre-scored and / or notched.

An inventive mold core for producing a fiber composite component, in particular a stiffening element on / on a base component in aerospace, is formed with a cork-comprising material and can be prepared as described above.

A fiber composite component with at least one stiffening element, in particular for aerospace, is produced with a mold core described above.

In a further embodiment, in the fiber composite component of the mold core is arranged in abutment with the at least one stiffening element as a noise damping means and / or thermal insulation element.

The invention will be explained in more detail with reference to the Ausführungsbeispie- Ie shown in the schematic figures of the drawing. It shows:

Fig. 1 is a schematic cross-sectional view of a stiffening element;

FIG. 2 shows the view according to FIG. 1 with a cross section of a first exemplary embodiment of a mold core according to the invention; FIG.

3 shows a schematic perspective view of an exemplary embodiment of a fiber composite component according to the invention during production according to a first method according to the invention; FIG. 4 shows a schematic cross-sectional view of the first embodiment of the mold core according to the invention according to FIG. 2 in a forming or core tool; FIG.

Fig. 5 shows a variation of the first embodiment of Fig. 4;

6 shows a schematic cross-sectional view of a second embodiment of the mold core according to the invention with the stiffening element according to FIG. 1;

Fig. 7 is a schematic cross-sectional view of a third

Embodiment of the molding core according to the invention with the stiffening element of FIG. 1;

8 shows a schematic cross-sectional view of a fourth embodiment of the mold core according to the invention with the stiffening element according to FIG. 1;

9 shows a schematic plan view of a plate product for the production of the fourth embodiment according to FIG. 8;

Fig. 10 is a side view of the plate product of Fig. 9;

Figure 11 is a schematic representation of a fixation of the mold core according to the first embodiment and the stiffening element of FIG. 1.

FIG. 12 shows a variation of the fixation shown in FIG. 11; FIG.

13 shows a schematic perspective view of the exemplary embodiment of a fiber composite component according to the invention during production according to a second method according to the invention; 14 shows a schematic cross-sectional view of a fifth embodiment of the mold core according to the invention with the stiffening element according to FIG. 1;

Fig. 15a is a schematic perspective view of a

Core blanks for a variation of the second embodiment of the mandrel according to the invention of FIG. 6;

Fig. 15b is a schematic perspective view of a processing of the core blank of Fig. 15a; and

15b is a schematic perspective view of a variation of the second embodiment of the mandrel according to the invention of FIG .. 6

In all figures of the drawing are the same or functionally identical elements - unless otherwise indicated - have been provided with the same reference numerals.

Reference is first made to FIGS. 1 to 3.

In Fig. 1 is a schematic cross-sectional view of a stiffening element 1 is illustrated. FIG. 2 shows the view according to FIG. 1 with a cross section of a first embodiment of a mold core 7 according to the invention, and FIG. 3 shows a schematic perspective view of an embodiment of a fiber composite component 10 according to the invention during production according to a first method according to the invention.

The stiffening element 1 in this example is a so-called Ω-stringer with a kind of hat profile, as shown in FIG. 1, and is perpendicular to the plane of the drawing. A perspective view is shown in Fig. 3, wherein by way of example two stiffening elements 1 are illustrated, the are applied to a base member 11, for example, a shell component or a fuselage skin of an aircraft and spacecraft, not shown, for stiffening.

The stiffening element 1 (see Fig. 1) has two opposite, obliquely upwardly converging webs 2, which are at their upper ends by a horizontal connection, here called head 5, connected. At the lower ends of the webs 2 each outwardly facing, horizontally extending feet 3 are attached to undersides. The undersides are provided as connecting surfaces 4 for support and for attachment to the base component 11 to be stiffened (see FIG. 3). The webs 2 and the head 5 enclose an approximately trapezoidal cavity 6, whose lower opening is closed by the base member 11 (see FIG. 3).

In FIG. 3, the stiffening elements 1 form a mold section 13 of the fiber composite component 10 with the base component 11. In each case, an inner surface section 12 is arranged on the surface of the base component 11 below a respective inner space 6 of the stiffening elements 1. In the interiors 6 of the stiffening elements 1 is in each case a mold core

7 arranged, as illustrated in Fig. 2 in cross section. However, it is also possible for a plurality of mandrels 7 to be arranged one behind the other.

In this example, the mandrel 7 fills the cavity 6 of the stiffening element 1 completely, wherein side surfaces

8 of the mold core 7 abut against the inner sides of the webs 2 and the head 5 of the stiffening element 1 and contact them. A mold core bottom surface 9 of the mold core 7 is aligned with the respective connecting surfaces 4 of the feet 3 of the stiffening element. 1

In this first embodiment of the invention

Method, the stiffening element 1 has already been produced at a different location, including the mold core 7 Ver. can find, and at least partially hardened. Here, the term partially hardened means that the stiffening element 1 is so far established in itself that it can be transported from its place of manufacture to the base element 11, which is still unheard in this example. In this case, the mold core 7 is located in the cavity 6 of the stiffening element 1. When arranged on the base member 11, the mold core bottom surface 9 covers the inner surface portion 12 of the surface of the uncured base member 11 between the connecting surfaces 4 of the feet of the stiffening element 1. With the connecting surfaces 4, the stiffening element 1 connected to the base member 11 in a further method step.

For this purpose, multistage application of at least the mold sections 13 in an autoclave with heat and / or pressure takes place in order to produce the fiber composite component 10 stiffened with the stiffening elements 1, the connecting surfaces 4 being connected to the base component 11. Various manufacturing processes can be used. Preferably, the so-called vacuum infusion process is selected here. However, the prepreg method is equally applicable here.

Here, the inner surface portions 12 of the surface of the base member 11 are supported and held by the mold core bottom surfaces 9 of the mandrels 7 so that no pores accumulations and fiber deflections in these skin fields of the inner surface portions 12 arise. This proves to be advantageous for the uniformity, strength and the course of force in the skin field structure.

In addition, the preparation of the mandrels 7 will be described with reference to FIGS 4 to 10.

4 shows a schematic sectional view of a first exemplary embodiment of a mold core 7 according to the invention in a cross section. The mandrel 7 consists of a core material having cork, for example cork flour with binders and fillers. It is also possible to use a compound of cork granules and rubber granules, which is called rubber cork. Also possible is a composite material consisting of at least one cork layer and at least one rubber layer. This core material is introduced into a core tool 14 and brought into this in the desired shape with the cross section of the mandrel 7, here an approximately trapezoidal shape. This can be done for example by pressing. By application of heat, the binders can be activated, such as rubber by vulcanizing agents. Other methods are of course possible.

In this example, the mold core 7 is surrounded by a separating layer 15 which completely encloses it on all sides and is suitable for its production process and further processing in terms of the process temperature and the process pressure. The separating layer 15 serves for correct separation of the mold core 7 both from the core tool 14 as well as from the stiffening element 1 and the base member 11 during demoulding. The surface finish of the release layer 15 is significant to the surface of the inner surface portion 12 (see Fig. 3). The release layer 15 can be created, for example, by grinding and polishing the mandrel 7 directly on the part. It is also possible to apply suitable coatings, for example of a plastic and / or liquid release agent and / or release film.

It is also possible in another embodiment that the mandrel 7 is cut to the desired cross-section. Then, for example, the core tool 14 can be schematically seen as a cutting tool.

FIG. 5 shows the core tool 14 with a mandrel 7 in a variation of different cross section, in which the lower corner areas are replaced by reinforcing means 17, for example strips of metal, plastic or cork and / or rubber cork. Thus, the mandrel 7 can obtain particularly well-formed corner regions by the reinforcing means 17 are made in a separate tool. When removing the mandrels 7 from the stiffening elements 1, these reinforcing means 17 can be removed depending on the design or remain in the stiffening element 1.

6 shows a schematic cross-sectional view of a second embodiment of the mold core 7 according to the invention with the stiffening element 1 according to FIG. 1. In this embodiment, the mold core 7 is formed with a core interior 18 which can be filled with another core during the production of the mold core 7 , This type of mandrel 7 is due to its low weight, for example, to remain in the stiffening element 1, wherein a possible core from the core interior 18 is removed.

Here, the mandrel 7 is used with a stiffening layer 16, which is for example a tear-resistant fabric layer. But it can also be another, stiffening material, such as a tear-resistant release film. This stiffening layer 16 can also be used instead of or as a separating layer 15 (see FIGS. 4 and 5). The stiffening layer 16 is particularly advantageous when the mandrel 7 is pulled out during demolding, as it protects it from damage and its reusability is increased.

In Fig. 7 is a schematic cross-sectional view of a third embodiment of the mandrel 7 according to the invention with the stiffening element 1 shown in FIG. 1, wherein the mandrel 7 is composed of three core segments 19 here. The core segments 19 here each have triangular cross sections, but are not limited thereto. The core segments 19 are firmly connected to each other, for example adhesive, wherein the adhesive for the temperatures and pressures in the manufacture of the fiber composite component 10 is suitable and resistant to the matrix materials used. This embodiment is suitable, for example, for larger core cross sections. The core segments 19 can be made by simple core tools 14.

8 illustrates a schematic cross-sectional view of a fourth exemplary embodiment of the shaped core 7 according to the invention with the stiffening element 1 according to FIG. 1. FIG. 9 shows a schematic plan view of a plate product 20 for producing the mandrel 7 of the fourth exemplary embodiment according to FIG and FIG. 10 shows a side view of the plate product 20 according to FIG. 9.

Like the second exemplary embodiment according to FIG. 6, the mold core 7 also has a core interior 18. The mold core 7 has a bottom wall 21 whose outer surface forms the mold core bottom surface 9. At the ends of the bottom wall 21, in each case a side wall 22 is connected in a folding section 24, the outer surfaces of the side walls 22 coming into contact with the inner surfaces of the webs 2 of the reinforcing element 1. The ends of the side walls 22 are also connected via folding sections 24 each having a top wall 23. The head walls 23 form with their outer surfaces a contact surface against the inner surface of the head 5 of the stiffening element 1. The free ends of the head walls 23 overlap and are connected together in a connecting portion 25, for example glued.

According to the fourth embodiment, the mandrel 7 is first cut as a folded core of sheet material 20 illustrated in FIG. 9. In Fig. 9, the plate 20 extends up and down in a certain length, which corresponds to the length of the mandrel 7 or is cut to it. In the width of the plate product 20, ie here in FIG. 9 from left to right, the above-mentioned The individual sections indicated in FIG. 8 are formed by scoring and / or scoring the folding sections 24. The connecting portion 25 is also cut obliquely in this example for overlapping. The folding sections 24 can, for example, additionally be provided with adhesive and / or fixed with adhesive strips after a folding operation. Fig. 10 shows a side view of the plate product 20. It can be seen here that the folding sections 24 in this embodiment have V-shaped notches. Optionally, the plate product can be provided on one and / or both sides with a release and / or autoclave film.

The sheet material 20 prepared in this way can now be subjected to a folding process according to the cross-section of the mold core 7 according to FIG. 8, for example by the side walls 22 with the head walls 23 attached thereto to the left and right around the bottom wall 21 in the clockwise and counterclockwise directions are folded, wherein the free ends of the head walls 23 overlap in the connecting portion 25 and are fastened to each other. The folding process can be carried out automatically in a suitable folding tool, for example in the longitudinal direction of the mandrel (perpendicular to the plane of the drawing of FIG. 9). In this case, serve a core with the cross section of the core interior 18 as a further folding tool, which is easy to imagine.

When transporting the stiffening elements 1 with internally arranged mandrels 7 as support cores, when arranging on the base member 11 and for other purposes, a fixation of stiffening element 1 and mandrel 7 may be necessary. 11 is a schematic view of a fixing of the mold core 7 according to the first embodiment and the stiffening element 1 of FIG. 1, and FIG. 12 illustrates a variation of the fixation shown in FIG. 11. Since, in the case of an at least partially hardened stiffening element 1, the inner surfaces are already prefabricated or finished in the cavity 6, it is possible for at least one of the side surfaces 8 of the mold core 7 bearing against the stiffening element 1 to be fixed with a fixation element. to provide element 26. In one embodiment, not shown, the fixing element 26 may be applied as adhesive tape alone, either on a side surface 8 and / or on an inner surface of the cavity 6 of the stiffening element 1. In the embodiment shown in FIGS. 11 and 12, the fixing element 26 is a magnetic strip or a metal strip / sheet. In FIG. 11, the fixing element 26 is provided with a cross section which allows the fixing element 26 to be introduced in the longitudinal direction of the mold core 7, wherein it is held positively in the mold core in the vertical direction due to the cross-sectional shape. Here, a recess with a cross-section corresponding to the fixing element 26 is formed in the upper portion of the mold core 7, wherein a surface of the Fixierungsele- element 26 abuts the inner surface of the head 5 of the stiffening element 1. On the opposite outer side of the head 5, a Fixierungshilfselement 27 is mounted, which cooperates with the fixing element 26 here via magnetic forces. The fixation auxiliary element 27 in this example is a sheet metal strip which can be magnetized.

Thus, a residue-free fixation of mandrel 7 and stiffening element 1 is possible, wherein the fixation auxiliary element 27 is applied with slight adhesion. Before a Autoklavfahrt after positioning the stiffening element on the base member 11, the fixing auxiliary element 27 is removed again. The fixing element 26 may also be glued into a simple recess, as shown in Fig. 12, in the side surface 8 of the mandrel 7. Fixation element 26 and fixation auxiliary element 27 may also be both magnetic strips. In the case of a thin-walled mold core 7, such as in the second embodiment of FIG. 6, the area in which the fixing element 26 is provided with a recess, must be thickened.

The mold core 7 according to the invention, which has a cork material, but can also be used in a manufacturing process in which the stiffening element 1 directly is formed on the base member 11. 13 shows a schematic perspective view of the exemplary embodiment of a fiber composite component 10 according to the invention during production in accordance with a second method according to the invention.

The mandrel 7 is here, for example, an embodiment with core interior 18 according to the second embodiment of FIG. 6. Two mandrels 7 are arranged on the base member 11, wherein their mold core bottom surfaces 9, the respective Innenflä- chenabschnitte 12 contact. The mandrels 7 are covered with one or more layers of semi-finished fiber 28, which are then impregnated with a matrix to form mold sections 13 with stiffening elements. However, the semifinished fiber product can also already be preimpregnated with resin and is then present as a prepreg. The curing process takes place as already explained above.

The invention is not limited to the illustrated in the figures, special method for producing a Faserverbundbau- part for aerospace.

For example, the present invention concept is also applicable to fiber composite components in sports equipment or motor sports.

Furthermore, the geometry of the mandrel is modifiable in a variety of ways.

Furthermore, a plurality of mandrels can also be used to form a mandrel. The aim is to create a more complex geometry by means of the large number of cores. As a result, more complex fiber composite components can be produced.

Also other stiffening profiles, such as T-stringer, L-stringer, U-stringer, tubes, mixed forms of said profiles and the like. can with the mold core 7 of the invention a cork having material supported as a support core. For this purpose, the mandrel 7 has the respective cross-section or the respective shape of the stiffening profile section to be supported. A fixation can be made, for example, as above according to FIG. 11 or 12.

The folding core according to FIG. 8 can also, as shown in FIG. 14 in a schematic cross-sectional view of a fifth exemplary embodiment of the mold core according to the invention with the stiffening element according to FIG. 1, have a surface overlap of two head walls 23 with a large-area connecting section 25 in the head region , This embodiment is particularly suitable for stiffening elements 1, which have already hardened and whose head area no longer has to be formed by the mandrel 7.

Instead of a folding core this can also be composed of individual plates.

It is also possible to produce the mold core 7 from a solid material. FIGS. 15a to 15c show schematic perspective views of a core blank 29 for a variation of the second exemplary embodiment of the mandrel according to the invention according to FIG. 6, its processing and final shape. For this purpose, the formation of this mandrel 7 as a hollow core with a core interior 18 has the following sub-steps: Provision of a core blank 29 or full profile, which is produced, for example, in a pressing process. The outer and inner contour of the mold core 7 is produced, for example, by means of milling and / or cutting tools 30. The outer geometry of the milling and / or cutting tool 30 for forming the core interior 18 corresponds to the geometric cross section of the core interior 18. The rotating milling and / or cutting tool 30 is moved in the longitudinal direction of the solid profile in selbigem, through the shaft 31 of the milling and / Cutting tool 30 at the same time a longitudinal gap 32 is introduced into the top wall 23 of the mold core thus manufactured. This longitudinal gap 32 can be closed with magnetic strip either with a glued strip of cork material and / or with a fixing element 26 (see, for example, Fig. 11, 12). The external geometry of the mandrel 7, which is to be adapted to the internal geometry of the reinforcing element 1, is produced by appropriate machining, for example milling and / or cutting, of the core blank 29. The core blank 29 may also be provided with the final outer profile.

The invention provides a method for producing a fiber composite component 10, in particular for aerospace, comprising the following method steps: forming a mold core 7 from a cork-comprising material with a core tool 14 for defining an outer geometry of the cork

Mold core 7; Arranging the mold core 7 thus formed in abutment against an at least partially hardened stiffening element 1 on a base component 11 of the fiber composite component 10 to be produced for shaping at least one mold section 13 of the fiber composite component 10 to be produced; and multi-stage applying at least the molding section 13 with heat and / or pressure for producing the fiber composite component 10; and a mold core 7 and a fiber composite component 10.

Preferred embodiments of the present invention

1. A method for producing a fiber composite component

(10), in particular for aerospace, comprising the following method steps: forming a mold core (7) made of a cork-comprising material with a core tool (14) for fixing an outer geometry of the mold core (7); Arranging the mold core (7) thus formed in contact with an at least partially hardened stiffening element (1) on a base component (11) of the fiber composite component (10) to be produced for shaping at least a mold section (13) of the fiber composite component (10) to be produced; and multi-stage applying at least the molding section (13) with heat and / or pressure for producing the fiber composite component (10).

2. Method according to embodiment 1, characterized in that at least one fixing element (26) is provided for fixing the mandrel (7) to the stiffening element (1).

3. Method according to embodiment 2, characterized in that the at least one fixing element (26) is attached to the mold core (7) and cooperates with at least one fixation element (27) removably attachable to the stiffening element (1), wherein, for example the at least one fixing element (26) and the at least one fixing auxiliary element (27) are formed with magnetic strips.

4. Method for producing a fiber composite component

(10), in particular for aerospace, with the following procedural steps:

Forming a mold core (7) of a cork-comprising material with a core tool (14) for fixing an outer geometry of the mold core (7); Arranging the mold core (7) formed in this way on a base component (11) of the fiber composite component (10) to be produced and at least partially depositing at least one semifinished fiber product (28) on the formed mold core (7) to form at least one mold portion (13) of the to be produced fiber composite component (10); and multi-stage loading at least of the mold section (13) with heat and / or pressure for producing the fiber composite component (10).

5. The method according to at least one of the preceding embodiments, characterized in that the mold core (7) is at least partially formed with at least one stiffening layer (16) of tear-resistant fabric and / or a tear-resistant release film.

6. The method according to at least one of the preceding embodiments, characterized in that when forming the mandrel (7) in the region of sharp edges trainees transitions of the outer geometry of the forming mandrel (7) to be formed reinforcing means (17) are arranged.

7. A method according to at least one of the preceding embodiments, characterized in that during and / or after the forming of the mandrel (7) a release layer (15) is applied to the mandrel (7), for example, by machining operations is produced by grinding and / or polishing and / or an additionally applied release film and / or a liquid release agent.

8. Method according to at least one of the preceding embodiments, characterized in that the mold core (7) is composed of at least two core segments (19).

9. Method according to at least one of the preceding embodiments, In other words, the mold core (7) is formed as a hollow core with a core interior (18).

10. Method according to at least one of the preceding exemplary embodiments, in which the forming of the mandrel (7) has the following substeps: provision of plate goods (20); Cutting blanks;

Folding the blanks with a folding tool; and joining the blanks using the core tool (14).

11. Method according to at least one of the exemplary embodiments 1 to 9, characterized in that the mold core (7) is formed by a pressing process.

12. mold core (7) for producing a fiber composite component (10), in particular a stiffening element (1) on a base member (11) for aerospace, wherein the mold core (7) with a cork-containing material is formed al.

13. Formed core (7) according to exemplary embodiment 12, characterized in that the shaped core (7) is produced by a method according to at least one of the exemplary embodiments 1 to 11.

14. fiber composite component (10) with at least one stiffening element (1), in particular for aerospace, which by means of a mandrel (7) according to embodiment 12 or 13 and / or a method according to at least one of the embodiments 1 to 11 is made.

15. fiber composite component (10) according to embodiment 14, characterized in that the mold core (7) in abutment with the at least one stiffening element (1) is arranged as a noise damping means, thermal insulation element, and / or to improve the impact behavior and / or the burn-through behavior.

C o m p a n c e m e n t i o n s

1 stiffening element

2 footbridge

3 feet

4 connection surface

5 head

6 cavity

7 mold core

8 side surface

9 mold core bottom surface

10 fiber composite component

11 basic component

12 inner surface section

13 molding section

14 core tool

15 separating layer

16 stiffening layer

17 reinforcing agents

18 core interior

19 core segment

20 plate goods

21 bottom wall

22 side wall

23 headboard

24 folding section

25 connecting section

26 fixing element

27 fixation aid

28 semi-finished fiber products

29 core blank

30 Milling and / or cutting tool

31 shaft

32 longitudinal gap

Claims

Patent claims

1. mold core (7) for producing a fiber composite component (10) of a stiffening element (1) on a base member (11) for aerospace, wherein the mandrel (7) with a cork material having a profile or as a hollow core with a core interior (18) is formed.

2. Mold core (7) according to claim 1, characterized in that the mold core (7) at least partially at least one stiffening layer (16) made of tear-resistant fabric and / or a tear-resistant release film has.

3. mold core (7) according to claim 1 or 2, d a d u r c h e c e n e c e in that the mold core (7) in the region of sharp-edged transitions its outer geometry with reinforcing means (17) is provided.

4. mold core (7) according to at least one of the preceding claims, dadur ch ge ke n e zne chne t that the mold core (7) from at least two core segments (19) is composed.

5. mold core (7) according to at least one of the preceding claims, dadur ch ge ke n zei chne t that the mold core (7) from folded blanks of a plate product (20) is formed.

6. A method for producing a fiber composite component

(10) Aerospace, with the following procedural steps:

Forming a mold core (7) according to one of the preceding claims from a cork material having a core tool (14) for fixing an outer geometry of the mold core (7);

Arranging the shaped core (7) thus formed in contact with an at least partially hardened stiffening element (1) on a base component (11) of the fiber composite component (10) to be produced, wherein at least one fixing element (26) for fixing the mold core (7) to the stiffening element (10) 1), or arranging the shaped core (7) formed in this way on a base component (11) of the fiber composite component (10) to be produced and at least partially depositing at least one semifinished fiber product (28) on the formed mandrel (7) to shape at least a mold section (13) of the fiber composite component (10) to be produced; and multi-stage applying at least the molding section (13) with heat and / or pressure for producing the fiber composite component (10).

7. The method according to claim 6, characterized in that the at least one fixing element (26) is attached to the mold core (7) and interacts with at least one fixation element (27) removably attachable to the stiffening element (1), wherein, for example, the at least one fixing element (26) and the at least one fixing auxiliary element (27) are formed with magnetic strips.

8. Method according to claim 6 or 7, characterized in that during and / or after the forming of the mandrel (7) a release layer (15) is applied to the mandrel (7), which is produced, for example, by machining operations by means of grinding and / or polishing and / or an additionally applied release film and / or a liquid separating agent.

9. Method according to claim 6, characterized in that the forming of the mandrel (7) has the following substeps:

Providing plate goods (20); Cutting blanks;

10. The method according to claim 6, characterized in that the mold core (7) is formed by a pressing process.

11. fiber composite component (10) with at least one stiffening element (1), in particular for aerospace, by means of a mandrel (7) according to at least one of claims 1 to 5 and / or a method according to at least one of claims 6 to 10 is produced, wherein the mold core (7) in abutment with the at least one stiffening element (1) is arranged as a noise damping means, thermal insulation element, and / or for improving the impact behavior and / or the burn-through behavior.