DE102008064676B4 - Method and device for producing a fiber composite component - Google Patents

Abstract

Method for producing a fiber composite component, in particular for a motor vehicle, comprising the steps of: a) providing a matrix material, at least in the form of matrix resins, b) applying the matrix material to individual reinforcing fibers or fiber bundles (14), c) merging the reinforcing fibers or fiber bundles (14 ) to which the matrix material has been applied, forming an impregnated fiber material (40) in the immediate vicinity in front of an adjustable shaping nozzle (44), d) forming the impregnated fiber material (40) through the shaping nozzle (44) into an impregnated fiber bundle (46). with special cross-sectional geometry and d1) application of the impregnated fiber bundle (46) on a two- or three-dimensional support structure, which simulates the shape of the fiber composite component, for producing a preform, wherein the arrangement of the fiber material based on the fiber composite component to be produced is power flow and voltage optimized, wherein the cross section geometry of the impregnated fiber bundle (46) is varied by means of the adjustable die (44) during the application of the impregnated fiber bundle (46) and thereby discontinuities or flattening of the deposited structures are set, which correspond locally different reinforcement requirements of the fiber composite component, and e) curing of the carrier structure applied matrix-impregnated fiber bundle (46) to form the fiber composite component.

Description

The invention relates to a method for producing a fiber composite component, in particular for a motor vehicle, and to an apparatus for carrying out this method.

In lightweight construction, especially in the automotive industry increasingly fiber-reinforced composite components are used for supporting structural components. For weight and cost-optimized lightweight construction with fiber composite components, the use of cost-determining materials, in particular the fiber content, must be minimized. For this purpose, it has been proposed that the fibers be integrated into the component structure in accordance with the flow of force without producing any fiber waste. This is achieved by various textile techniques, such. As braiding, weaving, sewing, etc., allows, which are used for the production of so-called fiber preforms (so-called preforms) for continuous fiber reinforced composite components. These methods allow the findings of force flow and stress analyzes in a corresponding textile reinforcing structure. When using an embroidery or sewing technique, the reinforcing fibers are fixed on a embroidery base with an embroidery machine according to the requirements of the analytical component calculation. A disadvantage of this method, however, is that after the preparation of the preform, the corresponding fiber structure must be impregnated with resin or plastic. This results in an additional process step, which significantly increases the cycle times of the manufacturing process. When using thermoset materials for producing the matrix of the fiber composite component are for this subsequent impregnation of the fiber structure so-called infusion process, such. As RTM (Resin Transfer Molding, SRIM (Structural Resin Injection Molding), or vacuum injection, available in which the plastic matrix is injected by means of a piston in a corresponding mold cavity of the fiber composite component and cures under heat and pressure., However, the infusion processes are relatively Furthermore, what are known as prepregs, which are usually referred to as continuous-fiber-reinforced thermoset semifinished products, is disadvantageous in these prepreg fibers, however, because of the nature of the resulting semi-finished products only for geometrically simple structures is applicable and also require a very high consumption of fiber material, as always a cutting of the prepreg must be made to the desired contour or shape of the fiber composite part significantly more expensive using prepregs.

Another disadvantage is that z. B. shell components over the entire surface must be made of the expensive composite material, although only in some areas structural properties are needed. The so-called Tailored Fiber Placement (use of narrow preimpregnated tapes) represents a further development. However, the restriction regarding component geometry and material usage also applies here.

To bypass the above mentioned disadvantages is in the US 2004/0119188 A1 a method is described which is intended to provide a preimpregnated continuous fiber bundle. For this purpose, first two separate continuous fiber bundles are prepared and preformed, which are then impregnated separately with one component each of a matrix resin. The individual resin components are not reactive and curable per se. Only when the two separate fiber bundles are brought together and formed into a single fiber bundle, the resin components form a reactive mixture, which is curable after placing the fiber bundle in its desired shape.

Although such a method allows a continuous impregnation of a continuous fiber bundle, which can be done almost simultaneously with its further processing, in particular with thermosetting or elastomeric matrix resins. Due to the separate pre-impregnation of two separate fiber bundles, the process, however, is technically and technically complex, especially since devices for rolling the continuous fibers, devices for their forms into a fiber bundle and devices for impregnating the fiber bundles must be provided in duplicate. Furthermore, especially in the case of a high number of individual fibers (so-called heavy tows), the shaping of a fiber bundle prior to its impregnation can be problematic, since the individual fibers can not slide against one another without damage, especially when forming very flat bands.

From the EP 0320649 A2 For example, a pultrusion process is known in which the ratio of resin to reinforcing fiber can be changed without interrupting production. This is done via an adjustable die.

From the EP 0269197 A2 a pultrusion process is known in which the material passes directly from a mold into a manufacturing mold. The fiber arrangement around the axis of the mold is maintained in the shape corresponding to the shape of the outer contour in cross-section of the final product.

The present invention is therefore based on the object, a method for producing a To provide fiber composite component, which allows an apparatus-technically simple continuous impregnation of a continuous fiber bundle, as well as an optimized shaping of such a fiber bundle.

It is a further object of the present invention to provide an apparatus for producing a fiber composite component, by means of which such a method is feasible.

The method according to the invention for producing a fiber composite component comprises the features of patent claim 1.

By combining reinforcing fibers and matrix material according to the invention, which is preferably present in the form of matrix resins and / or matrix fibers, it is possible to avoid the doubling of unwinding, shaping and impregnating devices known from the prior art. The process is therefore much simpler to implement. By directly applying the matrix material to the reinforcing fibers, which are provided as continuous fibers and the subsequent processing of these fibers by merging into an impregnated fiber material, which is available for subsequent textile processing, near-net shape preforms can be produced, which are then cured by a corresponding be converted into a corresponding fiber composite component.

When merging the reinforcing fibers and the matrix material takes place, at least for liquid matrix material, a substantially complete impregnation of the fibers or fiber bundles, so that air bubbles are largely displaced. The fiber material used is preferably the available continuous filament bundles or rovings, which typically have filament numbers in the range of 12,000 to 48,000 (12 to 48 K). In view of the high number of filaments and the goal of achieving as complete a impregnation as possible up to the innermost part of the bundle, the process step of bringing together is of particular importance. With the method step according to the invention, a dense fiber bundle can be provided for later storage.

Due to the immediate temporal and spatial proximity between the process steps of merging and depositing the impregnated fiber bundle, there are no longer any changes in the fiber / matrix ratio or the consistency of the fiber material.

In a further embodiment, the process of merging can also be designed so that the matrix / fiber ratio is locally varied. In this process step, excess matrix material can still be stripped off, thereby increasing the fiber content in the fiber material. This can be used, for example, for a local increase in the reinforcement effect in the target component.

It is particularly advantageous in this case to form the fiber material in a shaping die in process step d). This is to be understood as including a special cross-sectional geometry for the fiber material or impregnated fiber bundles. Depending on the application, different fiber material geometries are advantageous. For example, wide and flat fiber bundles can be adjusted, or even thick and narrow. Since the application of the mixed components to the reinforcing fibers is carried out before this forming step d), a better lubricity of the fibers against each other is ensured. This allows a low-damage sliding of the individual fibers together, so that, for example, very flat slivers with good strength properties can be formed.

When depositing the fiber material, or the impregnated fiber bundles to the preform, the orientation of the fibers is carried out under specific predetermined spatial directions. The fibers are aligned with respect to the later main load case of the fiber composite component to be produced, with optimized flow and voltage. Typically, this will be a parallel alignment with the main lines of force of the composite component. The erfindungemäße method allows machine-controlled to map complex contours and directional curves in a very simple manner.

By setting variable cross-sectional geometries of the fiber bundles during the depositing operation by means of the shaping nozzles, it is also possible in particular to generate precisely targeted thickening or flattening of the deposited structures; correspondingly locally different. Reinforcement requirements of the component.

Under the matrix material is to be understood the moldable and curable precursor of the later matrix of the corresponding composite component. These may be liquid curable resins or plastics. Likewise, plastic mixtures of moldable and curable portions are suitable. If fibers of matrix material (matrix fibers) are used, they act like the moldable precursor of the later matrix of the corresponding composite component.

Another type of matrix material are solid resins, which can be applied, for example, as a fine powder, or can be applied to the fiber in solution and dried. suitable Solid resins are intermediately meltable, so that before their curing in step e) a uniform infiltration of the reinforcing fibers can be done. Preferred resins include fusible phenolic resins, urethane polymers or unsaturated polyester resins which are thermally cured.

If matrix fibers are used, this is preferably done in the form of hybrid yarns of reinforcing fibers of matrix fibers. The matrix fibers are suitable for hardening in step e) also harden. If the matrix fibers are used without resin, only intermediately melting fiber types are suitable. These may be precrosslinked polymer fibers which cure completely thermally. If matrix fibers and resin are used, it is also possible to use non-meltable synthetic fibers, which can then be further hardened or crosslinked with the resin.

Since, during the curing or melting and curing of the matrix fibers, the impregnation or penetration of the reinforcing fibers and fiber bundles takes place automatically through the plastic matrix material, it is possible according to the invention to dispense with an additional impregnation step.

The curing can be carried out thermally and / or photoinitiated, or by cold curing.

Among the preferred curing methods is the thermal curing, especially under external pressure, because during or immediately before curing, the resin viscosity drops, or solid resins melt and the resin flows into the spaces formed by the fibers. The thermal curing is carried out by adapted heating, wherein the matrix fibers and / or the resin melt before curing below the curing temperature of the fiber material and thermally crosslink when reaching the curing temperature.

The photon initiated curing, especially by UV light, is preferably used for fiber material with liquid resins. Optionally, a photochemical pre-crosslinking and then a thermal end-crosslinking can be carried out first.

This results in reduced cycle times of the manufacturing process, so that the cost of manufacturing the fiber composite components can be significantly reduced.

It is particularly advantageous that the reinforcing fibers or fiber bundles are present together with the precursor of the matrix in a state of excellent formability, which is in addition to the direct deposition of emerging from the molding die material, in particular for the sophisticated knitting, weaving or Knüpfverfahren.

The reinforcing fiber or fiber bundles already provide the required matrix for the composite body to be molded. A separate process step of a resin impregnation, as required for example in the RTM process, is eliminated.

In addition, the inventive application of the fiber material allows a geometrically optimized application of the fiber material while avoiding fiber waste and optimum fiber utilization. The inventive method is extremely economical in the production of lightweight fiber composite structures, as is avoided by the endkonturtreuen preforms fiber waste, since the fiber material is optimally exploited by a power flow and voltage arrangement and also by the defined, low-defect fiber assembly high quality consistency of the fiber composite parts produced is guaranteed.

Resin and matrix fibers from the group of crosslinkable thermosetting and / or elastomeric plastics can be used as the matrix material.

Particularly suitable as the resin are the thermal, cold-curing or UV-curing polyesters, polyurethanes, epoxides, phenols or vinyl esters. As polymer blends vinyl ester polyurethane blends are particularly preferred.

In an advantageous embodiment of the method according to the invention takes place in step b) applying the plastic by means of a powder, melt or solvent impregnation. This ensures optimal wetting of the fibers or fiber bundles with the resin. Solid resin can be applied first in solution to the reinforcing fibers or rovings and then dried to a gel-like or solid topcoat.

In a further advantageous embodiment of the method according to the invention in step d) the application of the fiber material by depositing and / or weaving and / or braiding and / or embroidering and / or sewing on the support structure.

The support structure may be formed two- or three-dimensional, it may also be removed in a later step from the fiber composite part or remain on the fiber composite component. The aforementioned application techniques, in particular the mentioned sewing technique causes a defined, low-defect fiber arrangement and thus also contributes to optimal fiber material utilization with a high quality consistency. Furthermore, there is a much higher design freedom compared to the prior art.

Particularly preferably, the support structure is formed in three dimensions, in particular in the form of curved surfaces.

When sewing, no reinforcing fiber but a sewing thread made of cotton or plastic fibers is used in a preferred embodiment. The sewing thread essentially ensures only the firm fixation of the fiber material on the support structure. The sewing thread may consist of a fusible plastic, which dissolves during thermal curing. Another variance in the formation of the preform by the above deposition techniques is given in the use of the geometrically variable shaping dies.

In a further advantageous embodiment of the method according to the invention, the curing of the fiber composite material according to method step e) comprises pressing, the application of external pressure and / or heating of the fiber composite material. In this case, the preforms produced in process step d) can be pressed and cured in a preferably heated tool. Also, the use of so-called autoclave or microwave devices are conceivable in the curing step. The preform is preferably wrapped in a protective foil in a known manner in an autoclave in order to apply the external pressure over the surface of the fiber material.

In particular, depending on the matrix type, curing may be either integral, i. H. only when all fibers are deposited, or else differentially, that is to say fiber bundles are locally cured immediately after depositing.

The integral procedure is particularly advantageous, for example, when thermosetting matrix materials are used and the finished preform is introduced as a whole into a hardness oven.

Differential curing is possible, for example, for UV-curable matrix systems in that the fiber-laying head is followed by a UV curing lamp.

Glass fibers, carbon fibers, ceramic fibers, metal fibers, natural fibers or a mixture of at least two of these fiber materials are preferably used as reinforcing fibers. Other suitable reinforcing fibers are aramid fibers or high modulus polyethylene fibers.

The support structure may for example consist of a pre-crosslinked, solid at room temperature plastic, wherein the plastic of the support structure may correspond to the plastic of the matrix material. This ensures in an advantageous manner that during curing of the fiber material applied to the carrier structure, the plastic of the carrier structure can also contribute to the impregnation of the fiber material and does not act as a foreign material inclusions in the resulting fiber composite component.

In a further embodiment of the invention, the support structure consists of a pre-crosslinked plastic mold, which cures completely in process step e). The plastic of the support structure is preferably chemically related to the matrix material.

In a further embodiment, the support structure of a textile material or a paper-like material is constructed, which is impregnated with a resin which cures in step e). The cured support material typically remains as a flat and unreinforced fabric in the finished component.

If appropriate, the carrier structure can also be removed after curing of the fiber material in a further process step.

In a preferred embodiment, a functional part is integrated into the fiber composite component during sewing, embroidery or weaving. As a functional part in particular metallic connecting parts can act for attachment to a vehicle body. As another example, cables or media lines can be sewn on and integrated into the fiber structure.

The invention additionally relates to a fiber composite component, in particular a fiber composite component for a motor vehicle, produced by a method according to the invention described above. Preferred components are trim parts of the vehicle interior.

The invention further relates to an apparatus for producing a fiber composite component according to the method described above. Such a device comprises a mixing device for mixing at least two components of a matrix material, at least one application station for applying the mixed components to reinforcing fibers to form an impregnated fiber material, at least one confectioning station for applying the fiber material to one by weaving, embroidering, braiding, sewing or the like the shape of the fiber composite component replica support structure for producing a preform, and at least one curing station for curing the fiber composite material applied to the carrier structure.

Furthermore, a bundling and fiber-forming device for bundling and forming the impregnated fiber material is provided. Instead of pure reinforcing fibers, hybrid yarns of reinforcing and matrix fibers can also be used in such a device.

The inventive device ensures optimized fiber material utilization and a reduced cycle time of the production process for producing a fiber composite component. In particular, by a spatial and temporal separation of application station, bundling and fiber-forming device, assembly station and curing station, the production process can be rational, simple and fast. By applying matrix material made of resin to individual fibers or fiber bundles and the corresponding application of this coated fiber material in the confectioning on the corresponding support structure and the associated production endkonturtreuer preforms fiber blending is avoided, at the same time applied the individual fibers and fiber bundles kraftfluss- and voltage optimized can be. The resin can be selected from the group comprising thermosetting and elastomeric liquid or solid resins.

In advantageous embodiments of the device according to the invention, the application station has at least one impregnation nozzle and / or at least one resin or liquid resin bed. By means of the impregnation nozzle, the resin can be applied in liquid form or powder form to the fibers and fiber bundles. In the resin bed, the material may be contained in solid form, such as a powder or individual fibers, with the fibers and fiber bundles to be coated passed through the resin bed.

In a further advantageous embodiment of the device according to the invention, the packaging station has at least one weaving and / or embroidery and / or sewing device. In this case, the packaging station or the weaving and / or embroidery and / or sewing device can have a programmable control device, so that the prepreg fibers or fiber bundles are deposited on the carrier structure in accordance with the requirements of a component calculation calculated in advance and correspondingly stored in the control device can.

In a further advantageous embodiment of the device according to the invention, the curing station has at least one pressurizable and / or heatable tool, at least one autoclave or at least one microwave device, IR irradiation device or UV irradiation device. The devices mentioned allow the necessary curing of the preforms to the resulting fiber composite components.

In further advantageous embodiments of the invention, the fiber material consists of glass fibers, carbon fibers, or carbon fibers or carbon fibers, ceramic fibers, metal fibers, natural fibers or a mixture of at least two of these fiber materials.

In the following, the invention and its preferred embodiments will be explained in more detail with reference to the drawing, wherein the single figure shows a schematic representation of an apparatus for performing the method according to the invention.

To increase the clarity was in the figure on the representation of confectioning and curing station of the device 10 waived. These stations essentially correspond to the state of the art, and are not affected by the concept essential to the invention.

The figure shows a unwinding station 12 containing a plurality of fibers 14 , which for clarity are not all designated, provides.

With the fibers 14 these may be pure reinforcing fibers in the form of glass fibers, carbon fibers, aramid fibers, polyethylene fibers, ceramic fibers, metal fibers and / or natural fibers. However, it is also possible to use hybrid fibers of a mixture of such reinforcing fibers with crosslinkable or fusible matrix fibers.

The fibers 14 are from a plurality of coils 16 unwound and the application station 18 fed. This includes a funnel-shaped tapered housing 20 in which the fibers 14 over a first guide bar 22 to a resin distributor 24 be directed. The resin distributor 24 is over a line 26 with the mixing device 28 connected. In this mixer 28 are storage tanks 30 provided for various components of the matrix material used. Via cables 32 are these reservoirs 30 with a mixing chamber 34 connected, in which the components of the matrix material are mixed and then in the line 26 and to the resin distributor 24 to get redirected.

In the area of the lines 32 . 26 , as well as the mixing chamber 34 Of course, further control and metering devices can be provided, which are not shown here.

The in the storage containers 30 stored components of the matrix material are not reactive on their own and not curable, only after their mixing in the mixing chamber 34 the matrix material obtains its desired curability. About the resin distributor 24 This now curable matrix material on the fibers 14 applied. The fibers 14 Continue through a tapered area 36 the application station 18 merged until in the form of a fiber bundle in the bundling and fiber forming device 38 enter. The individual fibers 14 become a compact fiber bundle there 40 summarized whose properties, for example, by pulleys 42 can be further influenced. Furthermore, heating devices or other devices for energy coupling, for example by UV radiation, laser radiation or ultrasound coupling, can be present in the bundling and fiber-forming device, which bring the components of the matrix material to a first reaction in order, for example, to achieve pre-crosslinking of the matrix material.

In a mold-adjustable or exchangeable molding nozzle 44 Finally, the fiber bundle gets its final shape, here in the example as a flat sliver 46 , The geometry of the shaping nozzle is designed to be adjustable during the laying process. This sliver 46 can now be fed directly to a confectioning station, which is not shown here, where this sliver can be applied by weaving, embroidery, braiding, sewing or the like on a support structure and then cured.

Claims (8)

Method for producing a fiber composite component, in particular for a motor vehicle, comprising the steps of: a) providing a matrix material, at least in the form of matrix resins, b) applying the matrix material to individual reinforcing fibers or fiber bundles ( 14 ), c) merging the reinforcing fibers or fiber bundles ( 14 ) to which the matrix material has been applied, to form an impregnated fiber material ( 40 ) in the immediate vicinity in front of an adjustable shaping nozzle ( 44 ), d) shaping the impregnated fiber material ( 40 ) through the die ( 44 ) to an impregnated fiber bundle ( 46 ) with special cross-sectional geometry and d1) application of the impregnated fiber bundle ( 46 ) on a two- or three-dimensional support structure, which simulates the shape of the fiber composite component, for producing a preform, wherein the arrangement of the fiber material with respect to the fiber composite component to be produced flow and voltage optimized, wherein the cross-sectional geometry of the impregnated fiber bundle ( 46 ) by means of the adjustable die ( 44 ) during the application of the impregnated fiber bundle ( 46 ) and thereby adjusting thickening or flattening of the deposited structures which correspond locally to different reinforcement requirements of the fiber composite component, and e) curing the matrix-impregnated fiber bundle applied to the support structure (US Pat. 46 ) forming the fiber composite component. A method according to claim 1, characterized in that wide and flat or even thick and narrow fiber bundles are adjusted during the application. A method according to claim 1 or 2, characterized in that matrix fibers are additionally provided as matrix material, which are preferably used in the form of hybrid yarns of reinforcing fibers and matrix fibers, wherein matrix fibers are used from crosslinkable plastic fibers. Method according to one of the preceding claims, characterized in that the curing takes place thermally and / or photoinitiated and / or by ultrasound coupling, or by cold hardening and takes place only after the formation of the entire preform differentially or immediately after the fiber deposition. A method according to claim 4, characterized in that the thermal curing is carried out by heating, wherein the matrix fibers and / or the resin before curing below the curing temperature of the fiber material ( 40 . 46 ) and thermally crosslink at the curing temperature. Method according to one of the preceding claims, characterized in that are selected as the matrix material matrix resin or matrix fibers from the group of crosslinkable thermosetting and / or elastomeric plastics or the matrix resin from the group of thermal, cold curing or UV-curing polyesters, polyurethanes, epoxies, phenols or vinyl esters, especially vinyl ester polyurethane blends. Method according to one of the preceding claims, characterized in that when combining reinforcing fibers and matrix material, the matrix / fiber ratio is locally varied by stripping excess matrix material. Device for producing a fiber composite component, in particular for a motor vehicle, comprising: - an unwinding station ( 12 ) comprising a plurality of individual fibers of reinforcing fibers or fiber bundles ( 14 ), - an application station ( 18 ) with a resin distributor ( 24 ) for applying a matrix material to the individual reinforcing fibers or fiber bundles (US Pat. 14 ), wherein the resin distributor ( 24 ) with a mixing device ( 28 ) is connected for mixing at least two components of the matrix material, - one to the resin distributor ( 24 ) subsequent tapered area ( 20 . 36 ) for combining the impregnated reinforcing fibers or fiber bundles ( 14 ), - one to the rejuvenating area ( 20 . 36 ) subsequent bundling and fiber-forming device ( 38 ), in which individual fibers of reinforcing fibers or fiber bundles ( 14 ), ( 40 ) and the one form-adjustable shaping nozzle ( 44 ) whose geometry during application for varying the cross section of the impregnated fiber bundle ( 46 ) is configured adjustable, and - at least one confectioning station for applying the impregnated and shaped fiber material ( 46 ) by weaving, embroidering, braiding or stitching onto a carrier structure simulating the shape of the fiber composite component for producing a preform, and - and at least one curing station for curing the fiber composite material applied to the carrier structure.

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