WO2009033559A1

WO2009033559A1 - Method for the production of a fiber composite component

Info

Publication number: WO2009033559A1
Application number: PCT/EP2008/006935
Authority: WO
Inventors: Christoph Breu; Andreas Gessler
Original assignee: Eads Deutschland Gmbh
Priority date: 2007-09-06
Filing date: 2008-08-22
Publication date: 2009-03-19
Also published as: DE102007042287B4; DE102007042287A1

Abstract

The invention relates to a method for producing a fiber composite component (10'). Said method comprises the following steps: a) several planar layers of fiber material (12-1 to 12-3) are joined together, a fleece material (14) being inserted into at least one interstice bordered by at least one curved surface section (16-1, 16-2) of one of the layers of fiber material; b) the layers of fiber material (12-1 to 12-3) and the fleece material (14) are infiltrated with a matrix material; and c) the joined and infiltrated layers of fiber material (12-1 to 12-3) including the fleece material are cured.

Description

Process for producing a fiber composite component

The invention relates to a method for producing a fiber composite component.

The use of fiber-reinforced components, also referred to as fiber composite components, is particularly interesting because of their high specific strength (ratio of strength to weight) in many applications. A fiber composite material is a composite material, which generally consists of two components, namely a matrix and fibers embedded therein. By mutual interactions of these components, the material receives higher quality properties than either of the two components involved individually.

For the production of relatively thick-walled fiber composite components, it is known, a plurality of each two-dimensional fiber material layers, the z. B. each as a semi-finished fiber such. For example, a fabric or a scrim may be provided, stacked flat side on flat side over one another and embedded in a matrix (by infiltration with a resin and subsequent curing).

In addition to plate-flat component structures can thus relatively easily produce plate-shaped curved component structures.

For a variety of other desired geometries arises in practice, however, the problem that the fiber material layers can not be attached to each other over the entire surface. By way of example only, a component profile with a T-shaped profile cross section may be mentioned for this purpose. In this case, when laminating the fiber material layers "in the corner of the T", a disadvantageous cavity or "gusset region" may remain which, depending on the concrete production method, remains as a cavity on the finished component or is completely filled with the matrix component. According to a technique based on Applicant's internal operational knowledge, such interstices have already been filled with foam plastic cores, but this primarily serves to ensure a certain dimensional stability of the assembled construct before curing. With regard to the mechanical properties of the finished component, the foam plastic core used plays no significant role. Even attempts to fill such gaps by fiber material, were not satisfactory, as it lacks in practice so far "matching" and cost-effective textile structures.

It is an object of the present invention to eliminate the disadvantages described above and to provide a simple method for producing a fiber composite component, which method should also be suitable for more complicated component geometries.

According to the invention, a method for producing a fiber composite component is provided, which comprises the following steps:

Assembling a plurality of respectively flat fibrous material layers, wherein a nonwoven material is inserted into at least one intermediate space bounded by at least one curved surface section of one of the fibrous material layers,

- Infiltrieren the fiber material layers and the nonwoven material with a matrix material, and

- Curing of the assembled and infiltrated fibrous material layers including nonwoven material. The use of nonwoven material as a material for filling one or more spaces remaining when the fiber material layers are joined together makes it possible, in a simple and cost-effective manner, to produce the relevant fiber composite component in a consistent and high quality.

The term "nonwoven material" here refers to a material of loosely folded fibers whose strength is based essentially on the fiber's inherent adhesion. The fibers are confused in the nonwoven material.

Although the use of a nonwoven material with one or more preferred directions of fiber orientation is conceivable (anisotropic nonwoven material), it is provided according to a preferred embodiment of the invention that the nonwoven material is substantially isotropic. In this case, the fibers are completely stochastically oriented, such. B. in a random nonwoven fabric. In many applications or for many component geometries, the use of such a filling body, in which the fibers contained have no preferred fiber direction, is particularly advantageous. This not only because of the resulting, often particularly favorable mechanical component properties, but also with regard to the production of the packing and its introduction into the space in question. Because of the isotropy, the material orientation does not have to be considered in these process steps.

In a preferred embodiment, the nonwoven material is a consolidated nonwoven web. This can z. B. its processing or packaging to a suitable filler can be considerably simplified. The term "consolidated nonwoven" in particular includes any type of felt. When felt, the fibers were characterized by a mostly mechanical processing such. As "wet felting" or "dry felts ¹ " brought into a solidified form. In principle, the production method according to the invention is suitable for any fibrous materials and matrix materials. Particularly advantageous is the method for the production of components with relatively highly curved component sections. The fibers used for the fiber material layers are, for example, glass fibers, carbon fibers, synthetic synthetic fibers, steel fibers or natural fibers. As a matrix material, in particular plastics such. As thermosetting plastics (resins) interesting. However, these lists are only to be understood as examples. In addition, if desired, fillers or additives can be added in a manner known per se.

In one embodiment, it is provided that the same type of fiber is provided for the nonwoven material as for the fiber material layers to be assembled. The nonwoven material may in particular z. B. made of wool fibers and / or other textile fibers including synthetic fibers.

In a particularly preferred embodiment, it is provided that the nonwoven material to be used has previously been separated from a flat structure of a consolidated nonwoven. The solidified web structure can be particularly advantageous for. B. in the form of a nonwoven sheet or, with sufficient flexibility, rolled up in the form of a nonwoven material roll be kept. In the manufacture of fiber composite components according to the invention then a required filler can be separated in a suitable form from the consolidated web form, z. B. cut by a knife, and optionally placed in a desired final contour.

In particular, with relatively high strength of a nonwoven material held available as stock, this can be worked out very accurately from the filling material, in particular by means of an automated separating apparatus, in particular a cutting apparatus, even using CAD data. This results in a Licher time, cost and quality advantage, especially in a series production of fiber composite components.

In one embodiment, it is provided that the filler to be inserted into the at least one intermediate space is formed in one piece from solidified nonwoven material. In the case of separation or separation of the filling body from a flat, consolidated nonwoven fabric held as stock, this nonwoven fabric should therefore be dimensioned sufficiently (large) with regard to the required filler dimensions.

For many applications, it is therefore z. B. advantageous to provide the stock held as solidified sheet nonwoven material having a thickness of at least 1 cm. Of course, the required material thickness depends on the dimensions of the fiber composite component to be produced or the interspaces contained therein, so that in larger fiber composite components a dimensioning of prepared nonwoven or felt materials in many cases with a thickness of at least 0.1 m may be appropriate.

If fillers of greatly varying size and / or geometry are required in the production of the fiber composite components, then it is also advantageous to provide an assortment of differently sized, stockpiled solidified nonwoven materials. In this case, material waste can be considerably reduced in practice.

The infiltration of the fiber material layers as well as the nonwoven material can be carried out in the invention quite generally before or after the joining of the fiber material layers. In one embodiment, it is provided that initially dry semi-finished fiber products such. As tissues, braids, scrim, fiber mats, etc., and then infiltrated with a resin. With regard to the Design of semifinished fiber products, their assembly and infiltration, as well as in terms of the final curing process (eg thermal), can be used advantageously on the knowledge and methods well-known in the field of fiber composite technology. Therefore, it is not necessary to explain at this point an explanation of these manufacturing details to be used advantageously in the context of the present invention (eg infiltration by means of a standard infusion method such as VAP, VARI etc., hardening in an autoclave, etc.).

Advantageously, the invention is also compatible for the production of fiber composite components by means of textile preform technology and vacuum infusion process ("open mold"). Also, so-called prepregs (pre-impregnated fiber semi-finished products) can be processed as the required flat fiber material layers.

In one embodiment, it is provided that at least one of the fiber material layers represents an angled profile and the bending region forms the curved surface section adjoining the intermediate space. A simple example of such a profile is z. As a T-profile or double-T profile.

A preferred field of application of the method according to the invention is the production of structural components, in particular for vehicles, for example aircraft. An advantageous application is z. As the production of Kraf- tübertragungs- or force introduction elements or fittings, in particular with T-shaped cross section or double T-shaped cross-section. Such elements or fittings are of particular interest as structural components in aircraft construction (eg with dimensions of the order of magnitude of a few 10 cm to a few m). With the method according to the invention, it is possible in particular to manufacture components of reproducible quality, in which one or more bending regions of the two-dimensional fiber material layers inevitably form at least one wedge-like tapered intermediate space (gusset) during the assembly of the fiber material layers.

In particular, when a resulting gap is to be substantially completely filled, the necessity of a substantially wedge-shaped filling body ("gusset filler") often results in practice, which in the invention is provided in a simple and advantageous manner with regard to the mechanical properties of the finished component ,

With the invention, design-related cavities or intermediate spaces in textile preforms for the production of fiber composite components can be filled in a simple, cost-effective and with regard to the quality advantageous manner. In one embodiment, a felt is made in sufficient thickness with a suitable fibrous material (eg, same fibers as the fibrous material layers). The density of the felt and the resulting fiber content can be variably adjusted to the application. A prefabricated felt or felt web can z. B. be made with the help of knives and placed in any desired shape for the filler.

One and the same plate of consolidated nonwoven material, for. As a felt plate, can be used for many Füllkörpergeometrien. By means of a CNC-controlled cutting apparatus, a particularly reproducible result in the production of the filling body can be achieved. Various geometries are possible. The manufacture of the filler, z. As the cutting out of a gusset, can advantageously be made immediately before the need. Often particularly advantageous mechanical properties of the component as well as a simplification of the processing Processing of the nonwoven or felt material results when using material with fibers without preferred direction.

The invention will be further described by means of embodiments with reference to the accompanying drawings. They show:

1 the positioning of a filling body on a flat structure of textile semi-finished products,

2 the combination of two reinforcing profiles of textile semi-finished products including the filler body,

3 is a view corresponding to FIG. 2, after infiltration and curing,

4 shows a representation to illustrate the provision of a filling body by separation from a felt web,

5 shows a separated from the web in Fig. 4 felt body,

Fig. 6 is a view corresponding to FIG. 2 for a further component geometry, and

Fig. 7 is a view corresponding to FIG. 2 for a still further component geometry.

FIGS. 1 to 3 illustrate a method for producing a fiber composite component 10 '(FIG. 3) comprising three successively performed steps: a) joining three respective sheet-like fiber material layers 12-1, 12-2 and 12-3, wherein a felting roll 14 is inserted into a gap formed by two curved surface portions 16-1 and 16-2 of the fiber material layers 12-1 and 12- 2 is limited.

In the illustrated embodiment, for this purpose, as shown in Fig. 1, initially the suitably shaped Filzzwickel 14 is placed with a flat base on top of the fiber material layer 12-3. Then, as shown in FIG. 2, the two further fiber material layers 12-1 and 12-2 are added, so that the felt winding 14 is inserted in the intermediate space between the several (here: 3) fiber material layers. This results in a construct 10.

b) infiltrating the fiber material layers 12-1 to 12-3 and the felt roll 14 with a matrix material (not shown) (eg, epoxy resin), and the following

c) curing the joined and infiltrated fiber material layers 12-1 to 12-3 together with Filzzwickel 14th

The cured and firmly interconnected fiber layers, including interposed Filzzwickel are designated in Fig. 3 with 12'-1, 12'-2, 12'-3 and 14 '.

The component 10 'is in this embodiment, as shown in FIG. 3, a profile component with T-shaped cross-section and has due to the integration of the tethered and cured Filzzwickels 14' despite ease of manufacture, a high mechanical strength.

In Fig. 3, the length of the profile member 10 'for the sake of simplicity of the presentation is relatively short (compared to the dimensions of the Pofilquerschnitts) drawn. In practice, the method is particularly suitable for producing elongated, straight or curved profile components.

In the following description of further embodiments, the same reference numerals are used for equivalent components, each supplemented by a small letter to distinguish the embodiment. In this case, essentially only the differences from the exemplary embodiment (s) already described are dealt with and, moreover, explicit reference is made here to the description of preceding exemplary embodiments.

As far as the production of a packing generally formed of nonwoven material, such as felt filing 14 described above, can be accomplished in a variety of ways.

Figures 4 and 5 illustrate a particularly advantageous manner in practice of producing a filling body 14a (Figure 5).

Fig. 4 shows a felt plate (eg needle felt) 20a held as a supply. The felt panel 20a consists of an isotropic felt having a thickness d dimensioned sufficiently to separate required fillers therefrom.

4 shows sectional lines for the separation of packing of the shape of the filling body 14a shown in dashed lines. The corresponding processing of the Fiizplatte 20a is preferably automated, z. B. by means of a computer-controlled cutting apparatus.

It is understood that the wedge-shaped, prismatic shape of the filling body 14a shown in FIG. 5 is to be understood as an example only and to be described with the description given in FIG. NEN method also filler of a different geometry from the felt plate 20a can be separated or separated out (for example, the Filzzwickel 14 shown in Fig. 1).

FIGS. 6 and 7 illustrate further examples of assembled fiber material constructs 10b and 10c for producing fiber composite components 10b ¹ and 10c ^1, respectively.

In the example of Fig. 6, four layers of fibrous material 12b-1 to 12b-4, each designed as angled profiles, were assembled to form the construct 10b. After infiltration and curing of the construct 10b (including fleece filling 14b) results in a profile component with X-shaped profile cross-section.

In the example according to FIG. 7, in contrast to the embodiment described with reference to FIGS. 1 to 3, the third fiber material layer 12c-3 with a bulged profile region has been provided so that the interposed filler 14c is attached to three curved surface sections 16c-1 to 16c -3 adjacent.

It is understood that the details shown in the embodiments described above and in particular geometric shapes and dimensions can be widely modified in practice. What is essential is the use of a nonwoven material as a filling body for at least one intermediate space which is delimited by at least one curved surface section of one of a plurality of fiber material layers. The term "fiber material layer" is intended to include in particular so-called textile semi-finished products as they are well known in fiber composite technology. In this case, it is by no means impossible and even expedient, in particular for comparatively thick-walled fiber material layers, that these are each formed by superimposing a plurality of individual layers. Such a multi-layer fiber material layer can, for. B. during the assembly step described above. Alternatively, it is z. For example, it is possible to prefabricate multilayer fiber material layers, in particular as pre-impregnated and already partially cured fiber composite materials.

Claims

claims

1. A method for producing a fiber composite component (10 ¹ ), comprising the following steps:

- Joining a plurality of each two-dimensional fiber material layers (12-1 to 12-3), wherein a nonwoven material (14) is inserted into at least one space which is bounded by at least one curved surface portion (16-1, 16-2) one of the fiber material layers .

- Infiltrieren the fiber material layers (12-1 to 12-3) and the nonwoven material (14) with a matrix material, and

- Curing of the assembled and infiltrated fibrous material layers (12-1 to 12-3) together with nonwoven material.

2. The method of claim 1, wherein the nonwoven material (14) is substantially isotropic.

3. The method according to any one of the preceding claims, wherein the nonwoven material (14) is a consolidated nonwoven fabric.

4. The method according to any one of the preceding claims, wherein the nonwoven material (14) to be used has been previously separated from a flat structure (20) of a solidified nonwoven fabric.

5. The method according to any one of the preceding claims, wherein at least one of the fiber material layers (12-1 to 12-3) represents an angled profile and the Abwinkelungsbereich forms adjacent to the gap curved surface portion (16-1, 16-2).

6. fiber composite component (10 '), produced by a method according to one of claims 1 to 5.