DE102011052465B4 - Process for producing a fiber composite component - Google Patents

Abstract

Method for producing a fiber composite component (13), characterized by the following method steps: - providing a flat fiber material on a device, wherein a divided clamping frame (1) is used as device or that two clamping frames (12) are used; - Automated application of a resin (7) on the fiber material, wherein the clamping frame (1) is folded after the resin application or the two clamping frames (12) are folded after the resin application, so that the inner sides (5) of the fiber material inside each other come to rest ; - Pressure-free retraction of the resin (7) in the fiber material due to capillary forces (8) for a breakthrough time; - Further processing of the resin material (7) penetrated fiber material to a fiber composite component (13).

Description

The present invention relates to a method for producing a fiber composite component with the features in claim 1.

Nowadays fiber composite components are used in many technical fields. Fiber composite components are characterized by the fact that they have a low specific weight in relation to metallic components high or higher strength properties.

In the processing of fiber materials and the production of fiber composite components, the production tolerances still pose problems. The reproducibility of the production processes is highly dependent on the quality of each individual process step, in particular the fiber orientation and air inclusions during production are decisive for the achievable strength properties of the component to be produced.

In the field of automotive engineering, it is possible through the use of fiber composites to reduce the dead weight of a motor vehicle in such a way that it has a particularly advantageous effect on consumption and the associated CO ₂ emissions. Likewise, the handling capability of a motor vehicle increases due to a particularly light body or by means of particularly lightweight attachment components, which makes it more agile.

In the automotive industry, however, particularly high standards apply to the production accuracy and compliance with the required production tolerances, since the use of fiber composite components in the field of a motor vehicle body or as crashrelevantes component, directly affect the crash characteristics of the motor vehicle. In addition, high demands are placed by the motor vehicle manufacturer on the bending stiffness and torsional rigidity of structural components, since these in turn have a direct effect on the gap dimensions and the quality appearance of the vehicle due to avoided noise development in the vehicle interior.

For example, is from the DE 198 09 272 A1 a method for the production of motor vehicle components is known in which motor vehicle components are manufactured with high position quality. During the production process, however, due to the material, on the one hand there is a delay of the component geometry to be produced itself, on the other hand, in particular in the case of locally high degrees of deformation, to a distortion within the fiber material.

In order to control the distortion of the component geometry, hardening or cooling molds are known, in which the formed components are transferred after the molding process.

The distortion within the component, so the delay of the fiber orientation due to locally high degrees of deformation, which adversely affects the fiber orientation or on the fiber density, this is not compensated because he irreversibly in the forming component by the locally high degrees of deformation during forming is introduced.

By the DE 100 35 237 C1 a method is known with which it is possible to produce fiber composite components automatically. For this purpose, a fiber blank is provided in a tenter and then acted upon by a robot-controlled spray application with matrix resin. The component is then reshaped in such a way that a fiber composite forming component is produced and, at the same time, possible air inclusions within the component are pressed out of it. However, possibly trapped within the fiber composite air bubbles can not be pressed out with absolute certainty during the forming process of the fiber composite material. This would cause trapped air to weaken the material.

From the WO 86/00260 A1 , from the DE 29 42 729 A1 as well as from the DD 215 973 A5 For example, methods are known in which an endless fiber strand is passed through a resin bath and subsequently thermally treated to provide a preimpregnated fiber composite material. However, this requires an increased tool and energy cost to provide the fiber composite material.

It is therefore an object of the present invention, starting from the state of the art, to provide a method for producing a fiber composite component which has a particularly homogeneous material distribution within the component with little use of production tools.

The aforementioned object is achieved with a method for producing a fiber composite component according to the features in claim 1.

Advantageous embodiments of the present invention are part of the dependent claims.

• – Bereitstellen eines flächigen Faserwerkstoff auf einer Vorrichtung, wobei als Vorrichtung ein geteilter Spannrahmen verwendet wird oder dass zwei Spannrahmen verwendet werden;
• – Automatisiertes Auftragen eines Harzes auf den Faserwerkstoff, wobei der Spannrahmen nach dem Harzauftrag zusammengeklappt wird oder die beiden Spannrahmen nach dem Harzauftrag zusammengeklappt werden, so dass die Innenseiten des Faserwerkstoffs innenliegend gegenseitig zur Anlage kommen;
• – Druckloses Einziehen des Harzes in den Faserwerkstoff aufgrund von Kapillarkräften für eine Durchdringungszeit;
• – Weiterverarbeiten des mit Harz durchdrungenen Faserwerkstoffs zu einem Faserverbundbauteil.

The present invention relates to a method for producing a fiber composite component, the method comprising the following method steps:

• - Providing a sheet-like fiber material on a device, wherein as a device a split clamping frame is used or that two clamping frames are used;
• - Automated application of a resin on the fiber material, wherein the clamping frame is folded after the resin application or the two clamping frames are folded after the resin application, so that the inner sides of the fiber material inside each other come to rest;
• - Pressure-free drawing of the resin into the fiber material due to capillary forces for a breakthrough time;
• - Further processing of the resin-permeated fiber material to a fiber composite component.

With the method according to the invention, all common and known fiber composite materials can be processed first. These include, for example, glass fibers, aramid fibers, carbon fibers, basalt fibers but also metal fibers or other known fiber materials. Furthermore, mixed forms of the aforementioned fiber materials can be processed by the method according to the invention.

The fiber material is initially provided areally. In the context of the invention, a flat fiber material means a fiber layer or a fiber web. This means that the flat fiber material has an extension of at least several centimeters in length and width and in contrast to this in height an extension of only a few millimeters. In the context of the invention, it is also possible to process at least two fiber material layers, which are stacked one above the other. In particular, fiber materials can also be processed by the method according to the invention. This fiber materials are to be understood, which do not consist predominantly of fibers which extend in length or width across the complete fiber material or fiber material section or the fiber web. These are, for example, nonwovens or recycled fiber material pieces.

On the thus provided fiber material, a resin is first applied automatically. This process step according to the invention ensures that a uniform distribution of the resin has been applied to the fiber material provided. Preferably, an application is made to a workshop from above. This means that the fiber material is aligned substantially horizontally to the workshop and, accordingly, by means of automated application, a resin is applied to the fiber material from above.

This supports the subsequent process step of pressureless drawing of the resin into the fiber material due to capillary forces for a certain breakthrough time. The resin thus penetrates into the fiber material for the period of penetration due to capillary forces. This is supported by a substantially horizontal orientation of the fiber material by the gravitational force. However, the method according to the invention is also applicable to a vertical arrangement of the fiber material, which is essentially related to the assembly hall, since the drawing in of the resin is largely due to the capillary forces. In particular, the method according to the invention is characterized in that no further measures are essentially necessary in order to realize a homogeneous distribution of the resin in the fiber material. The inventive method thus differs significantly from those known from the prior art methods of preimpregnation or the resin injection. The uniform penetration of the resin due to the resin penetrating into the fiber material as a result of capillary forces avoids air pockets and thus significantly contributes to a homogeneous material distribution.

As a device for providing the fiber material, a split clamping frame is used or two clamping frames are used, which are folded after the resin application, so that the inner sides are internally opposed to each other. This provides a resinous fibrous material having a sandwich construction. Above and below is each a fiber material content, due to the hinged clamping frame or the two collapsed clamping frame and inside is a resin film, which is composed of two applied and folded sides.

Due to the capillary effect, the resin now migrates from the inner region of the sandwich component into the fiber material or the respective fiber material layers. At the latest during the pressing process in the forming tool itself thus takes place a complete and homogeneous penetration of the resin of the entire fiber material. Any air pockets within the fiber material itself are expressed by the resin migrating from the inside to the outside and are not trapped in the component itself.

In a final method step for producing a fiber composite component, the fiber material permeated with resin, ie fiber composite material, becomes a fiber composite component further processed. By this is meant, for example, a forming or shaping. It would also be possible within the scope of the invention to roughly preform the fiber mat, to allow it to cure and to further process it mechanically, for example by machining. It is likewise possible to punch out, saw out or mill out corresponding components from hardened, exclusively flat fiber composite materials.

The inventive method for producing the fiber composite component is characterized in particular by the fact that due to the retracting exclusively by capillary resin and the fiber interstices are filled. In particular, by the possible omission of other further post-processing measures, the fiber structure is not destroyed because no additional pressure or mechanical machining is applied from the outside to the resin-impregnated fiber material.

The inventive method is further characterized in particular by the fact that the fiber material is completely penetrated by resin before it is further processed. For this purpose, the fiber material after the automated application of a resin is first allowed to rest for a breakthrough time, so that all fiber interstices and fiber cavities are completely penetrated by the resin due to the capillary forces. Preferably, a penetration time of from 1 to 30 minutes, in particular from 2 to 20 minutes and very particularly preferably of about 5 minutes, is chosen. However, the breakthrough time is largely dependent on the thickness of the fiber material and / or consistency of the resin. The above-mentioned time specifications therefore apply in particular to a single-layer fiber material. In the case of the use of multilayer fiber materials, the penetration time per job and layer should preferably be added accordingly.

In a further preferred embodiment variant of the present invention, the penetrated fiber composite material is further processed with less than 10% air entrapment. In particular, further processing takes place at less than 5% air entrapment and particularly preferably at less than 1% air entrapment. As a result, it is ensured in the context of the invention that the fiber composite component to be produced has a homogeneous material distribution. The production tolerances can be reduced by applying the method according to the invention at very low production costs to a minimum, since the fiber composite and resin fiber composite material has a continuous homogeneous course. Depending on the accuracy requirement of the component to be manufactured, it is thus possible to work with the above-mentioned percentage air entrapment.

The inventive method is further characterized by the fact that optionally the resin is introduced into the fiber material exclusively by capillary forces. There are no further process steps and / or no additional tools needed. An exception is, for example, a squeegee, which allows a more homogeneous distribution of the applied resin. However, the introduction of the resin into the fiber material is not supported. As a result of this measure, which is essential to the invention, the production costs are reduced due to the omission of complex tool devices, for example for pre-impregnation or for resin injection. At the same time, however, high production reliability is realized due to the homogeneous distribution of the resin within the fiber material.

Particularly preferably, the resin is applied via a nozzle with an industrial robot, preferably in an uninterrupted application process, in particular at a temperature between 20 ° and 60 ° C., more preferably between 30 ° and 50 ° C. The order with an industrial robot ensures that a particularly homogeneous distribution of the resin takes place on the fiber material itself. An exact dosage is thereby possible, which is avoided by the retraction due to the capillary action in the fiber material resin that air pockets or resin excesses are introduced. The effect is enhanced by a single uninterrupted application process and / or by a temperature control of resin and / or fiber material.

In the context of the invention, a resin application can additionally take place by means of a meander-shaped pivoting movement of the nozzle. Also, this order form has been found to be particularly advantageous for a homogeneous introduction of the resin on the homogeneous fiber material.

The automated application of the resin can further optionally be supplemented by a doctor blade process. In the context of the invention, a squeegee is to be understood as a distributor strip with which the resin is additionally distributed by brushing with a squeegee during the spraying process and / or shortly after the spraying process. In a particularly preferred embodiment of the present invention, a combined spray-on and doctor blade tool is used.

Also preferred is the resin on only one. Side of the fiber material as a thin film applied. This is especially an inside of the fiber material.

In a further preferred embodiment, unidirectional fibers are introduced into the fiber material in preferred directions. These can already be introduced during the manufacturing process of the fiber material itself or else be applied to the fiber material, in particular also shortly before or with the spraying process of the resin, so that the unidirectional fibers are arranged in the interior of the sandwich component. As a result, the fiber composite component undergoes a significant increase in strength over conventional fiber material components, without continuous fiber reinforcement.

In a further preferred embodiment variant of the present invention, the clamping frame is positioned between an upper tool and a lower tool of the forming tool and moved toward the lower tool during a lowering operation of the upper tool with half the lowering speed of the upper tool. This ensures that both tool halves hit the fiber composite at the same time. It thus comes simultaneously to a system of fiber composite material on the lower tool and to a system of the upper tool on the fiber composite material. Consequently, the temperature entry of both upper tool and lower tool in the component to be produced is done equally. A homogeneous heat input thus ensures good curing and thus high reproducibility of the method according to the invention.

Further preferably, the fiber composite component cures in the forming tool for 0.1 to 20 minutes, preferably 1 to 15 minutes. Following this, the fiber composite component is removed from the forming tool or removed from the mold. Already after removal of the fiber composite component cools at the ambient temperature, but preferably it can also be placed in a separate downstream cooling device. It is possible to avoid distortion during cooling, so that the accuracy of fit of the component according to the invention is particularly high. Within the scope of the invention, it would also be possible to carry out the curing process in a separate mold holding tool and then to use a cooling process or a combined mold holding and cooling tool.

The method according to the present invention further produces a fiber composite component for a motor vehicle from a recycled and / or a reused fiber material made of fiber composite material.

The component is characterized in particular by the fact that the fiber material used for the production of the component is produced almost exclusively from recycled, reused fiber composite material, which is obtained as a waste product in the production of other fiber composite components. The method enables particularly short cycle times, high reproducibility of the component and thus only a small component tolerance. The components can thus also be used in strength-relevant application areas, the production costs being particularly cost-effective and economical in terms of process and environment due to the automation of the process and the reuse of the material.

Further advantages, features, characteristics and aspects of the present invention are part of the following description. Preferred embodiments will be apparent from the schematic figures. These are for easy understanding of the invention. Show it:

1 a split tenter according to the invention with a clamped nonwoven and resin impregnated areas;

2 a folded clamping frame;

3 a tensioned on a tenter fleece in a forming tool before the forming process and

4 the fleece off 3 after the forming process.

In the drawings, the same reference numerals are used for the same or similar component, even if a repeated description is omitted for reasons of simplicity.

1 shows a split clamping frame according to the invention 1 that's from a left half 2 and a right half 3 consists. In the left half 2 and in the right half 3 is each a fleece 4 clamped from unspecified reused and / or recycled fiber material. On the fleece 4 is on an inside 5 an area 6 with resin 7 has been homogeneously wetted, wherein a non-illustrated component to be produced in the area 6 is produced by a not shown forming tool. By a subsequent folding movement K, the left half 2 and the right half 3 folded over each other, so that the insides 5 each come to rest each other.

2 shows the split tenter 1 , where the right half 3 and the left half 2 were folded over each other, so that the fleece 4 the left half 2 and the fleece 4 the right half 3 lie one above the other or parallel to each other. The insides 5 Thus, they lie against one another and have a homogeneous resin layer, which is proportionally exaggerated here, lying between them. The resin 7 penetrates via capillary forces 8th in the fleece 4 one.

3 shows a forming tool 9 for producing a fiber composite component according to the invention 13 , being between an upper tool 10 and a lower tool 11 a tenter 12 is positioned. In the tenter frame 12 is a fleece 4 arranged that was acted upon by the method according to the invention with a resin not shown here. By lowering the upper tool 10 becomes the fleece 4 to a fiber composite component 13 according to 4 reshaped. It is possible that the clamping frame 12 in a balancing direction 14 yields, so that it does not lead to a demolition or cracking within the fleece 4 comes during the forming process.

LIST OF REFERENCE NUMBERS

1

divided clamping frame

2

left half

3

right half

4

fleece

5

inside

6

Area

7

resin

8th

capillary forces

9

forming tool

10

upper tool

11

lower tool

12

tenter

13

Fiber composite component

14

compensation direction

K

folding movement

Claims (9)

Method for producing a fiber composite component ( 13 ), characterized by the following method steps: - providing a flat fiber material on a device, wherein as a device a divided clamping frame ( 1 ) or that two clamping frames ( 12 ) be used; - Automated application of a resin ( 7 ) on the fiber material, the tenter frame ( 1 ) after the resin application is folded or the two clamping frames ( 12 ) are folded after the resin application, so that the insides ( 5 ) of the fiber material inside each other come to rest; - Pressure-free retraction of the resin ( 7 ) in the fiber material due to capillary forces ( 8th ) for a breakthrough time; - Further processing of resin ( 7 ) penetrated fiber material to a fiber composite component ( 13 ). Process according to claim 1, characterized in that the fiber material is completely filled with resin ( 7 ) is penetrated before it is further processed. A method according to claim 1 or 2, characterized in that the penetration time is 1 to 30 minutes, preferably 2 to 20 minutes, more preferably 5 minutes. Method according to one of the preceding claims, characterized in that the resin ( 7 ) is applied via a nozzle with an industrial robot, preferably in an uninterrupted application process, in particular at a temperature between 20 and 60 ° C, more preferably between 30 and 50 ° C. A method according to claim 4, characterized in that the resin is applied by a meandering pivoting movement of the nozzle. Method according to one of the preceding claims, characterized in that the sprayed-on resin ( 7 ) is spread with a doctor blade, preferably by a combined spray and doctor tool. Method according to one of the preceding claims, characterized in that the clamping frame ( 12 ) between an upper tool ( 10 ) and a lower tool ( 11 ) of the forming tool ( 9 ) is positioned and during a lowering operation of the upper tool ( 10 ) with half the lowering speed of the upper tool ( 10 ) on the lower tool ( 11 ) is moved. Method according to one of the preceding claims, characterized in that the fiber composite component ( 13 ) in the forming tool ( 9 ) is cured for 1 to 20 minutes, preferably 2 to 15 minutes. Method according to one of the preceding claims, characterized in that the demolded fiber composite component ( 13 ) is cooled, preferably in a cooling device.

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