DE102013010312A1 - Producing a fiber-reinforced plastic component, comprises heating at least one fiber semi-finished product comprising an electrically conductive reinforcing fiber of the plastic component by means of at least one heating element - Google Patents

Abstract

Producing a fiber-reinforced plastic component, comprises heating at least one fiber semi-finished product (16) comprising an electrically conductive reinforcing fiber of the plastic component by means of at least one heating element. At least one of the reinforcing fibers of the fiber semi-finished product is used as the heating element.

Description

The invention relates to a method for producing a fiber-reinforced plastic component according to the preamble of patent claim 1.

From the general state of the art, methods are known for producing fiber-reinforced plastic components, in particular fiber-reinforced structural components of motor vehicles, in which first a semi-finished fiber product, possibly provided with a binder, is inserted into a tool. By means of the tool, the semi-finished fiber provided with the binder is formed into a fiber preform, which is usually referred to as a preform, so that the tool is also referred to as a preform tool. By a heat in the preform mold, the binder is activated, thereby fixing a three-dimensional shape of the preform represented by the molding. In this case, for example, the fiber orientation of the fiber preform is determined.

Furthermore, by fixing several fiber preforms (preforms) can be fixed in a compacted state. The preform can then be infiltrated by means of an infusion process (for example, resin transfer molding (RTM) or vacuum assisted resin infusion (VARI)) with a resin which is subsequently cured by heat. For heating, usually at least one heating element is used, which is integrated in the preforming tool or in an infusion tool for infiltrating the preform with the resin. The use of integrated heating elements, however, requires a complex structure of the respective tool. Furthermore, the heating and a subsequent cooling of the tool lead to long cycle times and therefore to high costs of the manufacturing process. Following this, we each formed a fiber-reinforced plastic component in that the fiber preform is provided with plastic.

The DE 10 2008 043 527 A1 discloses a heating element which is inserted into a forming tool and can be used there for heating a component to be formed or shaped in the tool. However, such a heating element is not suitable for use in an infusion tool.

It is therefore an object of the present invention to develop a method for producing a fiber-reinforced plastic component of the type mentioned in such a way that the heating of the semifinished fiber product can be realized in a particularly cost-effective manner.

This object is achieved by a method having the features of patent claim 1. Advantageous embodiments with expedient and non-trivial developments of the invention are specified in the remaining claims.

In order to provide a method specified in the preamble of claim 1 species in which the semifinished fiber is heated in a particularly cost-effective manner, it is inventively provided that is used as the heating element at least one of the reinforcing fibers of the semifinished fiber. This means that for heating the semi-finished fiber no additional heating device provided in addition to the semifinished fiber product, but at least one, integrated in the semifinished fiber product or in the later, fiber-reinforced plastic component, electrically conductive reinforcing fiber is used. In other words, the reinforcing fiber of the semifinished fiber product is used in the manner of a heating wire by passing electrical current through the reinforcing fiber and thereby heating the heating of the semifinished fiber product is realized.

The plastic of the plastic component is for example a thermoplastic or a thermosetting plastic and represents a matrix material, with which the semifinished fiber product is provided, for example, in the context of the production of the fiber-reinforced plastic component. The reinforcing fibers are at least partially embedded in the thermoplastic or thermoset matrix material - for example a resin - in the form of the plastic. As a result of this fiber reinforcement a particularly low weight and at the same time a particularly high rigidity of the plastic component can be realized.

As part of the production of the fiber-reinforced plastic component at least one tool is used, by means of which the semifinished fiber product is formed and / or provided with the matrix material. Since the reinforcing fiber of the semi-finished fiber is used as a heating element, particularly inexpensive and, for example, isothermal tools can be used without integrated heaters in them. By means of the reinforcing fiber, the semifinished fiber product and the initially liquid matrix material can then be cured.

Alternatively or additionally, it is possible by the heating, a binder, with which the semi-finished fiber is provided, are activated, so as to fix, for example, a formed by molding the semifinished fiber shape of the semifinished fiber product. Such shaping of the semifinished fiber product and activation of the binder caused by the heating can be carried out in the context of the production of a binder Fiber preform (preforms) are used, wherein the preform is made from the semifinished fiber product and the binder. The preparation of the fiber preform is also referred to as preforming, wherein the activated binder serves to hold the fiber preform in its corresponding form after the preforming of the semifinished fiber product.

The resin or matrix material curing can take place after an infusion of the fiber preform and thus of the semi-finished fiber product with the matrix material. This infusion is carried out, for example, by means of a resin infusion process, which can be a resin transfer molding process (RTM process) or a vacuum assisted resin infusion process (VARI process).

Further, it is possible to activate by the heating an adhesive which is used for joining the fiber-reinforced plastic component or the semifinished fiber product with at least one further component, and / or to accelerate its curing.

It has proven to be particularly advantageous if electrical contacting of the reinforcing fiber is formed by a closing movement of the tool into which the semi-finished fiber product is introduced. In other words, the electrical contacting of the reinforcing fiber is coupled to the closing movement of the tool. For this purpose, the tool has, for example, at least one electrical contacting element, which is electrically contacted with the reinforcing fiber when the tool is closed. This allows electrical current to be passed through the reinforcing fiber for heating the reinforcing fiber and thus for heating the semifinished fiber product via the contacting element. By coupling the electrical contact with the closing movement of the tool time-consuming and costly process for electrical contacting of the reinforcing fiber can be avoided.

To realize a particularly large-area or complete heating of the semifinished fiber product, several or all electrically conductive reinforcing fibers of the semifinished fiber product can be used as the respective electrical resistance heating elements.

In an advantageous embodiment of the invention, the reinforcing fiber or the reinforcing fibers are electrically contacted in respective edge regions of the semifinished fiber, wherein for heating the reinforcing fiber or the reinforcing fibers, electrical current is passed through the reinforcing fiber or the reinforcing fibers in the longitudinal direction. It can be provided that the reinforcing fiber or the reinforcing fibers are or are electrically contacted in respective end regions.

Alternatively, for heating the reinforcing fiber (s), it is possible to conduct electrical current transverse to the longitudinal direction at the reinforcing fiber (s), i. H. in the radial direction to guide this through the reinforcing fiber or the reinforcing fibers. For this purpose, the semifinished fiber or the reinforcing fibers are electrically contacted, for example, surface and electrically heated resistance. As a result, for example, a particularly uniform heating of the semifinished fiber product can be realized.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawings; these show in:

1 a schematic sectional view through a tool according to a first embodiment for producing a fiber-reinforced plastic component, wherein in the tool a semi-finished fiber is received, which is heated by means of at least one heating element, wherein as the at least one heating element, an electrically conductive reinforcing fiber of the semifinished fiber is used;

2 a schematic sectional view through the tool according to a second embodiment;

3 a fragmentary sectional view of the tool according to the second embodiment; and

4 a schematic sectional view through the tool according to a third embodiment.

In the figures, identical or functionally identical elements are provided with the same reference numerals.

1 shows a schematic sectional view of a tool 10 According to a first embodiment, which is used in the context of a method for producing a fiber-reinforced plastic component, in particular a fiber-reinforced structural component. The tool 10 includes two mold halves 12 . 14 , which relative to each other between a in 1 shown closed position and at least one open position are movable. To open the tool 10 become the tool halves 12 . 14 moved away from each other, so that at least one semi-finished fiber 16 in the tool 10 can be inserted. The semifinished fiber product 16 is used for producing the fiber-reinforced plastic component and is formed from reinforcing fibers or comprises reinforcing fibers. The reinforcing fibers of the semifinished fiber product 16 are carbon fibers which are electrically conductive. The semifinished fiber product 16 may be part of a fiber preform, which is also commonly referred to as a preform. This is the semifinished fiber product 16 provided with a binder. By activating the binder can be, for example, by forming the first still formlabilen semi-finished fiber 16 or fiber preform produced form of the semifinished fiber product 16 be fixed. The activation of the binder is effected by a heat, which by heating the semifinished fiber product 16 in the tool 10 is realized. The tool 10 can for example for forming the semi-finished fiber 16 be used.

Alternatively or additionally, the tool 10 as an infusion tool for infiltrating the semifinished fiber product 16 or the fiber preform can be used with a thermosetting or thermoplastic matrix material. The matrix material is the plastic of the fiber-reinforced plastic component, wherein the reinforcing fibers of the semifinished fiber product 16 at least partially embedded in the plastic. The plastic may in particular be a resin, so that by means of the tool 10 For example, a resin infusion process is feasible.

The heating of the semifinished product infiltrated with the matrix material 16 in the tool 10 can thus also serve to cure the matrix material or the resin. The heating of the semifinished fiber product 16 takes place by means of electrical resistance heating elements. In this case, the electrical resistance heating elements are reinforcing fibers of the semifinished fiber product 16 used. In other words, at least part of the reinforcing fibers of the semi-finished fiber product 16 used as electrical resistance heating and thus on the type of heating wires to the semi-finished fiber 16 to heat. Thus, in addition to the semi-finished fiber 16 and to the tool 10 provided and in the tool 10 or in the semifinished fiber product 16 integrated heaters not required!

How out 1 can be seen, there is an electrical contacting of the reinforcing fibers, which are used as heating elements, at the ends or in respective edge regions 18 . 20 of the semifinished fiber product 16 , This is indicated by the tool 10 electrical contacting elements 22 . 24 on. About the electrical contacting elements 22 . 24 For example, an electrical voltage may be applied to the reinforcing fibers so that electrical current can be passed through the reinforcing fibers. This leads to a heating of the reinforcing fibers and thus to a heating of the semifinished fiber product 16 , As in 1 by a directional arrow 25 is indicated, the electric current flows in the longitudinal direction of the reinforcing fibers or carbon fibers in this case from the contacting element 22 to the contacting element 24 , The reinforcing fibers can thus be embedded or integrated completely into the matrix material in relation to their respective transverse direction, ie in the radial direction.

For electrical contacting of the reinforcing fibers protrude, for example, in respective areas of the contacting elements 22 . 24 out of the matrix material so that it makes electrical contact with the contacting elements 22 . 24 can train. The reinforcing fibers can also protrude from the finished, fiber-reinforced plastic component.

By using the reinforcing fibers as electrical heating elements for heating the semifinished fiber product 16 is a fast and direct electrical heating of semi-finished fiber or intermediate for processing with thermoplastic or thermoset matrix materials or for the production of preforms feasible. In other words, it is possible to cure by the described heating binder of preforms or semi-finished fiber to fix the shape of the respective preforms. Alternatively or additionally, it is possible by the described heating matrix materials with which preforms or semifinished fiber products are provided to heat quickly and directly and thus to be able to harden. With appropriate thermal insulation of the tool 10 Furthermore, a particularly energy-efficient heating is realized.

2 and 3 show the tool 10 According to a second embodiment, wherein also here the electrical contacting of the reinforcing fibers at the ends or in the respective edge regions 18 . 20 he follows. 3 shows an enlarged view of the tool 10 and the semifinished fiber product 16 at the edge 20 , In 3 is the finished and still in the tool 10 located, fiber reinforced plastic component recognizable, which in 2 and 3 With 26 is designated. Out 3 are also reinforcing fibers 28 of the semifinished fiber product 16 to recognize which in the border area 20 protrude from the matrix material. Otherwise, the reinforcing fibers 28 completely embedded in the matrix material in its transverse direction. Out 2 and 3 are also respective isolation elements 30 recognizable, by means of which the respective contacting elements 22 . 24 opposite the tool 10 or the tool halves 12 . 14 are electrically isolated.

The tool 10 according to the second embodiment can also be used for forming the fiber tool 16 used because the tool half 14 a stamp 32 and the tool half 12 one with the stamp 32 corresponding admission 34 having. Will the stamp 32 in the recording 34 when closing the tool 10 retracted, so is a part of the first still flat Faserhabzeugs 16 by means of the stamp 32 in the recording 34 pushed in, so that for example a particularly aus 2 recognizable hat shape of the fiber hoop 16 or of the fiber-reinforced plastic component 26 can be produced.

4 shows the tool 10 according to a third embodiment. In the third embodiment, it is provided that the electric current now flows not in the longitudinal direction but in the transverse direction, ie in the radial direction of the carbon fibers therethrough, as in 4 by a directional arrow 36 is illustrated.

The contacting elements 22 . 24 Cover with closed tool 10 the entire fiber hive 16 such that the electrical current perpendicular to the fiber direction from the contacting element through the carbon fibers to the contacting element 22 flows. Also in the third embodiment is an electrical insulation of the contacting elements 22 . 24 opposite the tool 10 intended.

To realize an electrical contact between the reinforcing fibers of the fiber tool 16 and the respective contacting elements 22 . 24 The reinforcing fibers are not completely embedded in the matrix material with respect to their transverse direction, but the reinforcing fibers or carbon fibers project out of the matrix material in their transverse direction. As a result, the reinforcing fibers can be the respective contacting elements 22 . 24 touch directly and thus be contacted electrically.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008043527 A1 [0004]

Claims (8)

Method for producing a fiber-reinforced plastic component ( 26 ), in which at least one semi-finished fiber product ( 16 ), which electrically conductive reinforcing fibers ( 28 ) for the plastic component ( 26 ), is heated by means of at least one heating element, characterized in that as a heating element at least one of the reinforcing fibers ( 28 ) of the semifinished fiber product ( 16 ) is used. Method according to claim 1, characterized in that the semi-finished fiber product ( 16 ) at least partially into a tool ( 10 ) for providing the semifinished fiber product ( 16 ) is introduced with a matrix material, wherein at least one electrical contacting of the reinforcing fiber ( 28 ) by a closing movement of a tool ( 10 ) is formed. Method according to one of claims 1 or 2, characterized in that the reinforcing fiber ( 28 ) in respective peripheral areas ( 18 . 20 ) of the fiber tool ( 16 ) is electrically contacted, wherein for heating the reinforcing fiber ( 28 ) Electric current in the longitudinal direction of the reinforcing fiber ( 28 ) is passed through this. Method according to claim 3, characterized in that the reinforcing fiber ( 28 ) is completely embedded in a matrix material, at least in a partial region of its longitudinal extent, with respect to its transverse direction. Method according to one of claims 1 or 2, characterized in that for heating the reinforcing fiber ( 28 ) electrical current transverse to the longitudinal direction of the reinforcing fiber ( 28 ) is passed through this. Method according to claim 5, characterized in that the reinforcing fiber ( 28 ) is at least partially embedded in a matrix material in relation to its transverse direction, at least in a partial region of its longitudinal extent, so that the reinforcing fiber ( 28 protruding in the portion in the transverse direction of the matrix material, wherein the reinforcing fiber ( 28 ) is electrically contacted in the subregion. Method according to one of the preceding claims, characterized in that by heating the fiber tool ( 16 ) a binder for fixing the fiber tool ( 16 ) and / or a matrix material, in particular a resin, with which the fiber tool ( 16 ), cured and / or an adhesive for joining the fiber tool ( 16 ) and / or the fiber-reinforced plastic component ( 26 ) is cured with another component. Method according to one of the preceding claims, characterized in that the fiber-reinforced plastic component ( 26 ) is produced in a transfer molding process.

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