DE102004028075A1 - Method for producing a fiber composite blank for a hollow plastic component involves production of a plastic core and its use together with a temporary additional core during braiding with a fiber material - Google Patents

Abstract

The method for producing a fiber composite blank (2) for a hollow plastic component involves production of a plastic core (1) and its use together with a temporary additional core (3) during braiding with a fiber material.

Description

The The present invention relates to a process for producing a Composite fiber semifinished product according to the features of claim 1.

at The design and construction of vehicle components is always the component weight is a limiting condition. With intelligent lightweight construction In addition to steel, other materials such as aluminum or magnesium for use. For quite some time, the possible uses of fiber reinforced Plastics explores, both for Karossierieaußenhautteile as well as structural parts or components of the body skeleton. Because of their low Weight and their high rigidity plastic components, reinforced with carbon fibers are, very promising. The carbon fibers are in the plastic injected and form a reinforcement or stiffening matrix. The carbon fibers can in more diverse Be present manner, for example in the form of a tissue, in the form of a Multiaxially laid, in the form of a chain-reinforced, unidirectional semi-finished product, in the form of a knitted fabric, in the form of a knitted fabric etc.

For the production a fiber reinforced plastic part must first a "preform" is produced from the fiber material, which corresponds to the component to be produced substantially and then in a special injection mold with a resin hardener mixture is overmoulded, resulting in a plastic component.

apart from purely flat Components such as e.g. Vehicle roofs, have many components, in particular structural components of vehicles, "connecting pieces" or flange pieces, where the components are connected to other components or for holding other components, e.g. Hoses, cables, Hinges, etc. are provided. If you have such complex components made of plastic, so must also the connection parts or connection flanges before the injection process be reproduced from the fiber material to a sufficient To achieve strength of the connecting parts or connecting flanges. It should be noted that carbon fibers practically not nearly längendehnbar are. For However, the carbon fibers of the preform part should have an optimum component strength also not too long or too entangled, but possible stretched in Preformteil present.

task The invention is a method for producing a fiber composite semi-finished product specify that for the later one Production of a hollow plastic part with a connection piece or with several fittings or connecting flanges is suitable.

These The object is solved by the features of claim 1. advantageous Refinements and developments of the invention are the dependent claims remove.

For the production a hollow plastic part having on its outside one or more fittings or has one or more flanges, must first a Semi-finished fiber composite are made, the one plastic part has substantially corresponding shape, i. especially already the or the fittings or connecting flanges.

For the production of such a fiber composite semi-finished product, a first "core part" is first required, the hereinafter referred to as "plastic core". The outer contour the plastic part core corresponds essentially to the inner contour of the plastic part to be produced. According to the invention, in addition to the plastic core part used a second core, in the following is referred to as "additional core". The additional core is at the outer contour arranged the plastic core part. The plastic part core and the Additional core together form a core element, which is referred to below as "braid core".

The actual production of fiber composite semi-finished by "braiding" of the braided core with fiber material. The term "braiding" is very willing to understand and not to a specific "textile structure" set. The term braiding includes in particular a lichen in the strict sense, but also the Production of a fabric, a knitted fabric, a knitted fabric as well other textile structures. Representing all conceivable textiles Structures are described in the following description and in the claims Used terms "braiding", "braid" or "braiding".

To the braiding of the plastic part core and the additional core formed braid core, the additional core of the plastic core part, i.e. removed from the "braid". Subsequently, will the braid applied to the plastic part core. This can be, for example done by smoothing by hand. In the area where during the braiding process the additional core was arranged, lies after removal of the additional core a "surplus" of braid before. The excess braid is e.g. by smoothening by hand or by means of a tool brought into the shape of the connecting part or the connecting flange.

While the plastic core part in wesentli Chen corresponds to the inner contour of the plastic part to be produced, the additional core does not need to have a fixed predetermined shape. It is essential, however, that the additional core is designed such that the braiding has a sufficient fiber length for the production of the desired flange (s). With the additional core so a "braid reserve" is reached, which is just so great that from it or the desired flange can be formed. The geometry of the additional core is designed so that the unwinding lengths of the braid correspond exactly to the later fiber lengths of the fiber composite semi-finished product.

To a development of the invention, the braid before removal of the additional core in transition areas fixed between the plastic part core and the additional core on the plastic part core. This can e.g. by gluing with a double sided tape or done with an adhesive fleece. The adhesive tape or adhesive fleece Can already before the beginning of the braiding process on the plastic core part glued on. The adhesive tape or tape has the purpose that the braid after removal of the additional core not on the Plastic dividing core slips, but properly positioned remains.

Of the Plastic core can be made of different materials become. Suitable materials are in particular wax or foundry sand. Suitable but there are also many other materials. In the additional core can for example, one made of a sheet material airtight, inflatable body act. While of the braiding process, the auxiliary body is inflated. To remove the additional core is the gas contained in the additional core or the therein contained air drained. Age native to the additional core can also be made of a plastic foam. Suitable for this is in particular expanded polystyrene, which is also known under the brand name "Styrofoam".

in the Following, the invention will be explained in connection with the drawings. It demonstrate

1 - 4 various steps in the production of a fiber composite semi-finished product; and

5 An embodiment of a fiber composite semifinished product with a substantially circular cylindrical cross-section and a plate-shaped flange.

The 1 - 4 show a schematic representation of individual steps in the production of a fiber composite semi-finished product 1 , First, a plastic core part 1 manufactured, whose outer contour substantially the inner contour of a fiber composite semi-finished product to be produced 2 equivalent. The plastic part core can be made for example of wax or molding sand. Furthermore, an additional core 3 made, the outside of the plastic part core 1 is arranged. The additional core 3 For example, it may be an inflatable foil core. Alternatively, it may also be a plastic foam core, in particular a core of expanded polystyrene. In the case of the very simple embodiment shown here, both the plastic dividing core 1 as well as the additional core 3 cuboid. The plastic part core 1 and the additional core 3 Together they form a "wickerwork core".

When the braided core is ready, the braided core is braided with a fibrous material, eg with carbon fibers, whereby the fiber composite is semi-finished 2 receives. The braid can be a woven fabric, a knitted fabric, a knitted fabric or another textile structure.

After the braiding process, the additional core is removed. To prevent after the removal of the additional core, the fiber composite semi-finished 2 on the plastic part core 1 slipped, before braiding on the plastic part core 1 in the transition region between the plastic part core 1 and the additional core 3 a double-sided adhesive fleece 4 . 5 applied, which ensures that the fiber composite semi-finished 2 on the plastic part core 1 sticks.

After removal or extraction of the additional core 3 will, as in 3 represented, the fiber composite semi-finished product 2 by means of a tool 6 or by hand to the plastic dividing core 1 applied or smoothed. In the embodiment shown here, the fiber composite semi-finished product 2 painted so smoothly and folded that in the lower part of the fiber composite semi-finished product 2 a plate-shaped "braid flange 7 " forms.

This in 4 shown fiber composite semi-finished products 2 represents a "preform", which can now be introduced into an injection mold and can be overmolded with plastic, in particular with a resin-hardener mixture, resulting in a fiber-reinforced plastic part. After encapsulation of the fiber composite semifinished product 2 becomes the plastic part core 1 removed, so that there is a hollow fiber-reinforced plastic part. The plastic part corresponds in shape substantially to the in 4 shown fiber composite semifinished product, that is, it has a substantially rectangular tube portion and a substantially plate-shaped flange portion. As the plate-shaped flange area 7 integral with the rectangular Be rich of the fiber composite semi-finished product is connected, and not, as in the prior art, subsequently formed, results in a comparatively high strength of the flange 7 ,

That in the 1 - 4 Embodiment shown is merely an extremely schematically illustrated embodiment, which explains the basic principle of the invention. Of course, much more complex components with a plurality of flanges or fittings can be made in this way.

5 shows a fiber composite semi-finished product 2 , which takes the form of a circular tube cylinder with a plate-shaped flange 7 and also after the in the 1 - 4 described method was made by braiding a braid core formed by a plastic core and an additional core. After braiding the braid core, the additional core was removed and the fiber composite semi-finished product 2 in the in 5 Form shown reshaped.

Claims (12)

Process for producing a fiber composite semifinished product ( 2 ) for the production of a hollow plastic part, comprising the following steps: - producing a plastic part core ( 1 ), whose outer contour corresponds substantially to the inner contour of the plastic part to be produced; - arranging an additional core ( 3 ) at least in a partial region of the outer contour of the plastic part core ( 1 ), wherein the plastic part core ( 1 ) and the additional core ( 3 ) form a braided core; Producing a braiding by braiding the braid core ( 1 . 3 ) with fiber material; - Removal of the additional core ( 3 ) of the plastic part core ( 1 ) and - applying the braid to the plastic dividing core ( 1 ) in the region of the plastic part core ( 1 ) removed additional core from the braid at least one of the plastic core part protruding braid area ( 7 ) is formed. The method of claim 1, wherein the fibrous material at least partially made of carbon fibers. Method according to claim 1 or 2, wherein in the region of the plastic part core ( 1 ) removed additional core ( 3 ) from the braid at least one of the plastic part core ( 1 ) projecting flange-like braid area ( 7 ), which reinforces a flange of the plastic part in the plastic part to be produced. Method according to one of claims 1 to 3, wherein the braid after removal of the additional core ( 3 ) on the plastic part core ( 1 ) and in the area of the removed additional core ( 3 ) to one of the plastic part core ( 1 ) protruding flange braid area is folded, which reinforces a flange of the plastic part in the produced plastic part. Method according to one of claims 1 to 4, wherein the braid prior to removal of the additional core in transition areas between the plastic part core ( 1 ) and the additional core ( 3 ) on the plastic part core ( 1 ) is fixed. The method of claim 5, wherein the fixation by Gluing is done. A method according to claim 5 or 6, wherein the fixing takes place by a double-sided adhesive film or by a double-sided adhesive nonwoven, which before the braiding on the plastic core part ( 1 ) is applied. Method according to one of claims 1 to 7, wherein the plastic part core ( 1 ) is made of a waxy material. Method according to one of claims 1 to 7, wherein the plastic part core ( 1 ) is made of molding sand. Method according to one of claims 1 to 9, wherein the additional core is an inflatable body made of a sheet material, being the body while of the braiding is inflated and before removing the additional core Fluid from the body is drained. Method according to one of claims 1 to 9, wherein the additional core made of a plastic foam. Method according to one of claims 1 to 9 or 11, wherein the additional core consists of expanded polystyrene.