Sandwich component and method for producing a sandwich component

Abstract

A sandwich component has a first cover layer, a second cover layer, and a core disposed therebetween. In the sandwich component, the cover layers are each formed from an outer layer made of a fiber-reinforced thermoplast material having greater resistance to a certain solvent and, fused therewith, an inner layer made of a thermoplast material having lower resistance to the solvent. The core has outer layers, each of which is formed from a thermoplast material having lower resistance to the solvent, and an inner structure, which is formed entirely or partially from a thermoplast material having greater resistance to the solvent. The inner layers of the cover layers were each fused with one of the outer layers of the core with the use of the solvent.

Claims

1. A sandwich component, comprising: a first cover layer, a second cover layer, and a core disposed therebetween, wherein the first and second cover layers are each formed from an outer layer made of a fiber-reinforced PEEK and, fused therewith, an inner layer made of PEI, the core has outer layers each of which is formed from PEI, and an inner structure, which is formed entirely or partially from PEEK, and the inner layers of the cover layers are each fused with one of the outer layers of the core with the use of an organic solvent.

2. The sandwich component according to claim 1, wherein the core is a honeycomb core.

3. The sandwich component according to claim 2, wherein the honeycomb core is a folded honeycomb structure.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a prefabrication of a cover layer for a sandwich component;

(2) FIG. 2 shows the prefabricated cover layer;

(3) FIG. 3 shows a prefabrication of a thermoplast film for use as the starting material for producing a folded honeycomb structure;

(4) FIG. 4 shows the prefabricated thermoplast film;

(5) FIG. 5 shows a prefabrication of the folded honeycomb structure made of the thermoplast film depicted in FIG. 4;

(6) FIG. 6 shows a fabrication of the sandwich component by fusing two cover layers of the type depicted in FIG. 2 having a core prefabricated according to the method depicted in FIG. 5; and

(7) FIG. 7 shows the finished sandwich component.

DETAILED DESCRIPTION OF THE DRAWINGS

(8) FIGS. 1 to 7 depict the production of a sandwich component according to one exemplary embodiment.

(9) The configuration of the finished sandwich component 10 will be addressed first, with reference to FIG. 7. Next, the method used to produce the sandwich component 10 will be described with reference to FIGS. 1 to 6.

(10) FIG. 7 shows the finished sandwich component 10, comprising a first cover layer 12-1, a second cover layer 12-2, and a core 14 disposed therebetween.

(11) The cover layers 12-1 and 12-2 are each formed from an outer layer 16-1 made of a fiber-reinforced thermoplast material having greater resistance to a predetermined solvent (e.g., DCM) and, fused therewith (e.g., thermally fused therewith), an inner layer 18-1 of a thermoplast material having lower resistance to the predetermined solvent.

(12) In the example shown, the outer layer 16-1 is a fiber composite material, in the case of which a single- or multiple-layer carbon fiber material is embedded in a matrix of PEEK. In this example, PEEK is a thermoplast material of the cover layer 12-1 that is substantially resistant to an application of DCM, i.e., when DCM is applied, this thermoplast material is hardly attacked and, in particular, is not softened (partially dissolved) to a notable extent. Such a thermoplast material is referred to in the following simply as solvent-resistant or DCM-resistant.

(13) In contrast, the inner layer 18-1 in the example shown is formed from PEI, which, in this example, is a thermoplast material of the cover layer 12-1 that can be softened (partially dissolved) by application of DCM, for example. Such a thermoplast material is referred to in the following simply as non-solvent-resistant or non-DCM-resistant.

(14) The core 14 comprises outer layers 20-1 and 20-2 facing the cover layers 12-1, 12-2, respectively, each of which is formed from a non-DCM-resistant thermoplast material, specifically PEI in this case, and comprises a honeycomb-type inner structure 22, which is formed partially of DCM-resistant thermoplast material, specifically PEEK in this case, and partially of non-DCM-resistant thermoplast material, specifically PEI in this case.

(15) The inner layers 18-1, 18-2 of the cover layers 12-1, 12-2 are fused with one of the outer layers 20-1, 20-2, respectively, of the core 14, wherein the fusion was carried out by the mutual joining of the relevant fusion (joining) surfaces by application of DCM.

(16) The sandwich component 10 can be used particularly advantageously, e.g., as a component, in particular as a horizontally extended component (fuselage section, panel, etc.) in vehicle or aircraft construction.

(17) FIGS. 1 to 6 show individual steps or stages in the production of the sandwich component 10 depicted in FIG. 7.

(18) In a first step, the cover layers 12-1, 12-2 and the core 14 are prefabricated.

(19) The prefabrication of the cover layers 12-1 and 12-2 is carried outas illustrated in FIG. 1 for the cover layer 12-1 as an exampleby a mutual fusion (cohesive connection, preferably by means of thermal fusion) of the outer layer 16-1, which was previously produced using composite fiber technology, with the inner layer 18-1, which was previously produced, e.g., by extrusion. The resultant product, i.e., the cover layer 12-1, is depicted in FIG. 2. The prefabrication of the second cover layer 12-2 takes place in a similar manner. As an alternative to a purely thermal fusion of the outer layer 16-1 and the inner layer 18-1, these layers 16,1, 18-1 could be fused with one another, e.g., also with the use of a solvent, wherein the two materials, PEEK and PEI, can be softened (partially dissolved) in a manner suitable for such a fusion by the application of said solvent.

(20) In deviation from the method illustrated in FIGS. 1 and 2, it is possible to apply the inner layer by lamination already during the prefabrication of the outer layer, i.e., to embed the fibrous material in the outer layer and connect the inner layer in one step, e.g., in a shaping tool.

(21) The prefabrication of the core 14 is illustrated in FIGS. 3 to 5.

(22) First, as shown in FIG. 3, a prefabricated film 30 made of PEEK is coated on both sides with films 32-1 and 32-2 made of PEI. Preferably, the film 30 and the films 32-1, 32-2 are cohesively connected to one another, i.e., are fused (preferably thermally in this case as well).

(23) The resultant product is a compound film 34, which is shown in FIG. 4.

(24) Next, as symbolized in FIG. 5, a folded honeycomb structure, which is the core 14 (FIG. 5, right) is created by means of a reshaping process with the compound film 34 as the starting material (FIG. 5, left).

(25) In the example shown, the core 14 is therefore formed as a so-called folded honeycomb or a folded honeycomb structure. With respect to the reshaping process used therefor, reference can be advantageously made to the related prior art.

(26) In the example shown, a reshaping process was selected, by which, in particular, upper and lower honeycomb structure cover layers were also formed from the correspondingly shaped (and folded) starting material 34.

(27) Since these honeycomb structure cover layers (as well as the inner structure) are formed from the compound film 34 and, in this compound film 34, both surfaces of the films 32-1, 32-2 are formed from PEI, i.e., from a non-DCM-resistant thermoplast material, it is ensured that the core 14 resulting from the reshaping process has outer layers 20-1, 20-2 made of non-DCM-resistant thermoplast material.

(28) The latter is significant for the final step in the production of the sandwich component, which is illustrated in FIG. 6. In this step, the prefabricated core 14 is disposed between the two cover layers 12-1, 12-2, as shown. Next, the inner layers 18-1, 18-2 of the cover layers 12-1, 12-2 are fused with one of the outer layers 20-1, 20-2, respectively, after application of DCM at least on the joining surfaces to be fused together, with the application of pressure and, optionally, at a relatively high temperature, e.g., a temperature above room temperature. The result is the finished sandwich component 10 depicted in FIG. 7.

(29) In the above-described exemplary embodiment, the film 30 made of PEEK was completely coated on both sides with the films 32-1 and 32-2 made of PEI.

(30) As a result, the inner structure of the core 14 is formed partially of PEEK (film 30) and partially of PEI (films 32-1, 32-2).

(31) In the final production step for the sandwich component, care must be taken to ensure that largely no unwanted damage occurs, e.g., softening of the thermoplast portions present in the inner structure 22 of the core 14, which are not resistant to the relevant solvent, specifically DCM in this case. This can be taken into account in practical application, e.g., by setting the process conditions for the application of the relevant solvent, which is DCM in this case, such that this solvent does not penetrate the region of the inner structure 22 of the core 14 to a notable extent or in harmful quantities.

(32) With respect to this aspect, according to an advantageous development of the provision of the folded honeycomb structure by reshaping a film made of a solvent-resistant thermoplast material coated with a non-solvent-resistant thermoplast material, this coating is carried out only in regions, according to the specific reshaping process, such that the non-solvent-resistant thermoplast material is present on the finished folded honeycomb structure only in the region of the folded honeycomb structure cover layers.

(33) Therefore, e.g., the above-described exemplary embodiment could be advantageously modified such that the PEI coating on both sides of the PEEK film 30, as illustrated in FIGS. 4 and 5, is not carried out over the entire surface, but rather only in strip-shaped regions 36 as indicated by dashed lines in FIG. 5, said strip-shaped regions alternating with non-coated regions 38 in the processing direction of the compound film 34, wherein the width of the strips 36 and 38 relative to the processing direction is selected such that, as a result of the reshaping process, the inner structure 22 of the core 14 is formed only from the non-coated regions 38, i.e., PEEK, whereas the cover layers 20-1 and 20-2 of the core 14 are formed from the PEI-coated regions 36, in the compound with the PEEK film 30.

(34) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.