DE102011051071A1 - Process for producing fiber-reinforced molded parts - Google Patents

Abstract

The present invention relates to a method for producing fiber-reinforced molded parts with the following steps: providing a mold for the molded part to be produced, placing a plurality of fibers on the mold, and impregnating the fibers with a matrix material. The strength and the further material properties of molded parts produced in this way depend in particular on how the fibers are arranged in the mold before they are soaked with the matrix material. The strength of such molded parts is weakened in particular by waves and kinks in the fibers. However, checking the fibers by eye and by hand is time-consuming and, since the fibers are usually arranged in a large number of layers, can only detect the topmost or a few layers of the fibers. In contrast, it is the object of the present invention to provide a method for producing fiber-reinforced molded parts which enables the fibers in a mold for such a molded part to be checked for their correct position before the fibers are soaked with the matrix material. To this end, the invention proposes a method for producing fiber-reinforced molded parts with the steps of providing a mold (9) for the molded part to be produced, placing a plurality of fibers (4) on the mold (9), and irradiating the fibers (4) with electromagnetic radiation (2 ) in the THz frequency range, detecting the electromagnetic radiation (2) reflected by the fibers (4) and / or the electromagnetic radiation (2) transmitted through the fibers (4), identifying a fault location (8) in the fibers (4) using the electromagnetic radiation (2) reflected by the fibers (4) and / or the electromagnetic radiation (2) transmitted through the fibers (4), if a fault location (8) in the fibers (4) is identified, correcting the fault location (8), and impregnating the fibers (4) with a matrix material.

Description

The present invention relates to a method for producing fiber-reinforced molded parts comprising the steps of providing a mold for the molded part to be produced, laying a plurality of fibers on the mold and impregnating the fibers with a matrix material.

Fiber-reinforced components prevail in all areas of construction and daily life. They have a significantly improved strength in comparison to identical parts without fiber reinforcement. In other words, significantly greater amounts of material are required to achieve the same strength values with conventional materials, so that comparable parts made with conventional materials have a considerably higher weight.

Accordingly, fiber-reinforced materials find their application, in particular in the automotive industry, in aircraft construction and in the production of wings and components of wind turbines. For these applications, primarily fiber-reinforced plastics are used. However, fiber-reinforced materials are also found, for example, as fiber-reinforced concrete in the construction industry.

Common to all fiber reinforced materials is that a plurality of reinforcing fibers are embedded in a surrounding matrix material. In particular, the fibers are glass fibers, carbon fibers, ceramic fibers, aramid fibers, boron fibers, steel fibers, natural fibers and nylon fibers.

A distinction is made between fiber-reinforced materials with so-called continuous fibers, which are usually embedded in the form of layers and fabrics in the matrix, and materials with short, isotropically distributed or long fibers in the matrix.

In the choice of matrix materials, two groups are distinguished, namely plastic matrix materials and others, for example cement and concrete, metals, ceramics and carbon.

In fiber reinforced continuous filament materials, molded articles of these materials are often made by first providing a mold for the molded article to be formed, then laying a plurality of fibers, mostly in the form of sheets and webs, onto the mold and then an impregnating matrix material the fibers are poured into the mold.

The strength and the further material properties of such fiber-reinforced molded parts depend in particular on how the fibers are arranged in the mold before impregnation with the matrix material.

The strength of such moldings is weakened in particular by waves and kinks in the fibers. Therefore, prior to pouring the mold with the matrix material, the fibers applied to the mold must be checked carefully by eye and by hand for such imperfections in the fibers. However, such a review is time consuming and, since the fibers are mostly arranged in a plurality of layers, can only detect the topmost or a few layers of the fibers.

A weakening of a molded part resulting from the defects of the fiber layers can then only be determined after embedding the fibers in the matrix with different test methods. However, the consequence of detecting weakening of a molded article after embedding the fibers in the matrix and subsequently curing is that the entire molded article must be discarded.

In contrast, it is an object of the present invention to provide a method for producing fiber-reinforced molded parts, which makes it possible to check the fibers in a mold for such a molding prior to impregnation of the fibers with the matrix material to its correct position.

Against this background, a method for producing fiber-reinforced molded parts is proposed according to the invention with the steps: providing a mold for the molded part, applying a plurality of fibers to the mold, irradiating the fibers with electromagnetic radiation in the THz frequency range, detecting the fibers reflected by the fibers electromagnetic radiation and / or the electromagnetic radiation transmitted through the fibers, identifying a fault location of the fibers based on the electromagnetic radiation reflected by the fibers and / or the electromagnetic radiation transmitted through the fibers, if flaws in the image of the fibers are identified, correcting the flaws , and impregnating the fibers with a matrix material.

In the context of the present application, electromagnetic radiation in the THz frequency range is understood as meaning electromagnetic radiation having a frequency in the range from 1 GHz to 30 THz. Commercially available radiation sources and radiation receivers are now available in this frequency range. The THz frequency range has the advantage that many materials, in particular plastics, are transparent to electromagnetic radiation in this frequency range. Here is the electromagnetic radiation in the THz frequency range, in contrast to, for example, X-radiation non-ionizing.

The method according to the invention for the production of glass fiber reinforced plastics is particularly expedient, wherein the reinforcing fibers are glass fibers and the matrix material is a plastic. Suitable plastics as matrix material for fiber-reinforced plastics are in particular duromers (also thermosets or synthetic resins), elastomers and thermoplastics.

However, the method according to the invention is also suitable for producing fiber-reinforced molded parts with other fibers and with other matrix materials as plastics, as summarized in the introduction to the description.

The detection of a fault of the fibers makes it possible to exchange the fibers placed on the mold before the impregnation of the fibers with a matrix material or to correct their position in the mold. This is understood in the sense of the present application as correcting a fault.

While identifying a fault location of the fibers, i. the detection of kinks, undulations in the fibers laid on the mold, manually, i. by an observer of an image displayed, for example, on a screen, it is also possible, in one embodiment, to perform such identification using more modern imaging and image recognition algorithms.

In general, it is sufficient to irradiate the fibers at a single location or a selected plurality of locations with the electromagnetic radiation in the THz frequency range and to detect the radiation reflected from that location or transmitted through that location. This can be done, for example, at neuralgic, i. happen for vulnerable points in the form. However, in one embodiment, the irradiation and detection is done for a plurality of locations of the fibers such that an image of the fibers is generated.

In one embodiment of the invention, a plurality of layers of fibers, for example in the form of woven or laid, are applied to the form. In one embodiment, it is expedient if, in a first step, at least one layer of fibers is placed on the mold, the layer of fibers is irradiated with electromagnetic radiation in the THz frequency range and the radiation reflected by or transmitted through the fibers is detected , an error location of the fibers is identified by the radiation reflected from the fibers or by the radiation transmitted through the fibers and if a defect of the fibers is identified, the defect is corrected and then in a second step another layer of fibers or a plurality of layers of Fibers is placed on the mold, the fibers are irradiated again with electromagnetic radiation in the THz frequency range and is detected by the fibers reflected or transmitted by the radiation, a fault of the fibers on the basis of the fibers reflected or transmitted through the fibers radiation ident and if an error location of the fibers is identified, the error location is corrected.

In this way, a thick layer of fiber layers can be tested, even if the penetration depth of the electromagnetic radiation in the THz frequency range is less than the thickness of all the layers of fibers together.

In an embodiment of the invention, the steps of irradiating the fibers with electromagnetic radiation in the THz frequency range and detecting the electromagnetic radiation reflected by the fibers and / or the electromagnetic radiation transmitted through the fibers comprise the steps of: generating electromagnetic radiation in the THz- Frequency range with a radiation source, directing the electromagnetic radiation to the fibers, detecting the electromagnetic radiation reflected by the fibers with a radiation receiver and / or detecting the electromagnetic radiation transmitted through the fibers with a radiation receiver.

In this case, the generation and the detection of the electromagnetic radiation can take place both in reflection geometry and in transmission geometry. That In particular, images can be recorded both in reflection geometry and in transmission geometry.

Fiber-reinforced molded parts can be produced by very different embodiments of the method. One of them is referred to as filament winding wherein dry fibers (i.e., without matrix material) are wound onto a substantially cylindrical core as a shape. After winding it is necessary to determine whether the fibers, which are mostly wound up in the form of woven or laid fibers, have corrugations. For this purpose, the electromagnetic radiation in the THz frequency range is directed onto the fibers from outside and the electromagnetic radiation reflected by the fibers is detected by a radiation receiver.

In alternative embodiments, which are particularly suitable for producing more complex moldings, the shape of at least one Sectionally concave body formed on or in which the fibers are loaded or inserted.

As described above for the fiber winding, also in such an embodiment of the method, the fibers can be detected in reflection geometry, wherein the radiation is directed onto the fibers from the open side of the mold.

In an alternative embodiment, however, the shape itself consists of a material which is transparent to the electromagnetic radiation in the THz frequency range, so that irradiation and detection of the reflected or transmitted radiation can take place in reflection or transmission geometry, with the electromagnetic radiation passing through the form , This is particularly advantageous in the production of large moldings, since it is thus possible to detect the position of the fibers in the mold with a corresponding arrangement of radiation source and radiation receiver below the mold, while leaving over the mold free space to work.

In a further embodiment of the method according to the invention, the step of impregnating the fibers with a matrix material comprises applying a film to the fibers, sealing the film against the mold, evacuating a volume between the film and the mold, and introducing liquid matrix material into it the volume between the foil and the mold. Such a process is referred to as vacuum infusion for impregnating the fibers.

In one embodiment, a separating fabric is additionally introduced between the fibers and the film and, in addition, a distribution medium is introduced between the separating fabric and the film in order to allow uniform flow of the matrix.

By evacuating a volume between the film and the mold, i. by applying a vacuum, preferably by means of a vacuum pump, the air pressure compresses and fixes the fibers in the mold. In addition, the liquid matrix material is sucked into the fiber material by the applied vacuum and is distributed uniformly there.

In one embodiment of the invention, prior to loading the fibers into the mold, the mold is coated with a release agent to facilitate demoulding of the mold from the mold.

In one embodiment of the invention, the molded part is cured after impregnation of the fibers with a matrix material, wherein after curing and before or after removal of the molded part from the mold, the molded article is irradiated with electromagnetic radiation in the THz frequency range and reflected from the molded part or is detected by this transmitted radiation.

On the basis of such a measurement and, where appropriate, image formation of the finished molding, delaminations, i. Detach detachment of the matrix from the fibers in the finished part.

In one embodiment of the invention, the irradiation and detection or the generation of the image takes place with the aid of RADAR (Radio Detection and Ranging). In particular, the transit time or the path of the radiation from the radiation source via the hollow body to the radiation receiver is determined from the detected radiation.

Basically, there are three methods to be distinguished for a propagation or travel measurement of the electromagnetic radiation between the radiation source and the radiation receiver, all of which provide the same information about the distance between the object to be tested and the radiation source or the radiation receiver:

In a first embodiment, the step of generating electromagnetic radiation in the THz frequency range with the radiation source comprises frequency modulating the electromagnetic radiation, wherein the change in frequency is preferably constant over time, and wherein the step of detecting the electromagnetic radiation with the radiation receiver comprises Determining the difference frequency between a reference signal and the electromagnetic radiation received by the radiation receiver, and wherein the transit time of the electromagnetic radiation between the radiation source and the radiation receiver is calculated from the difference frequency.

Such a method for measuring the distance between the hollow body and / or the seal works particularly well if the frequency of the generated electromagnetic radiation is varied continuously over time, so that each time of the emission is clearly encoded by the radiated frequency. Such a method of distance measurement is also referred to as FMCW radar.

In order to be able to determine the difference frequency between the electromagnetic frequency radiated by the radiation source in the THz frequency range and the radiation received at the defined time by the radiation receiver, in one embodiment a coherent detection takes place at the radiation receiver, in which a reference signal is mixed by the radiation source with the received signal to produce a signal at the difference frequency.

Assuming that the radiation source and the radiation receiver have substantially the same distance from the fibers to be detected, the distance r (simple distance) between the radiation source and the fibers can be determined as follows from the generated difference frequency Δf between the frequency calculate electromagnetic radiation generated by the radiation source at a defined time and calculate electromagnetic radiation detected at the defined time in the radiation receiver: r = c / 2Δt = c / 2Δf / df / dt, where c is the speed of light and t is the time it takes for the electromagnetic radiation generated and radiated by the radiation source to travel at the speed of light back and forth from the distance r to the reflecting object, here the fibers. The ratio df / dt denotes the rate of change with which the frequency f of the generated and radiated electromagnetic radiation is changed over time t. This is also called Chirprate.

Alternatively to the use of an FMCW radar, in one embodiment of the method according to the invention the step of generating electromagnetic radiation in the THz frequency range with the radiation source comprises generating in the time domain pulsed electromagnetic radiation. The duration of a pulse with a short pulse duration compared to the distance to be detected is easy to determine. For this purpose, the transit time between the radiation source, the hollow body and the radiation receiver can be compared with the transit time of a reference pulse via a known path. Such a method is called impulse RADAR.

Alternatively, the step of generating the electromagnetic radiation in the THz frequency range with the radiation source comprises generating and emitting a plurality of frequencies sequentially, and the step of detecting the electromagnetic radiation with the radiation receiver comprises measuring the phase of the electromagnetic radiation for each individual frequency relative to a reference signal. From the measurement of the relative phase angles of the individual radiation components with a plurality of mutually different frequencies, the transit time or the travel path between the radiation source, fibers and radiation receiver can likewise be determined unambiguously.

In embodiments of the method according to the invention, the radiation source and / or the radiation receiver is moved relative to the fibers. This is particularly indicated when the molded part to be produced is a very large part, such as a wind turbine blade.

Although it is conceivable that in one embodiment the radiation receiver has only a single pixel, in embodiments the radiation receiver has a plurality of pixels which are arranged in a line-shaped or matrix-shaped manner.

Depending on the number of pixels and their arrangement in the radiation receiver, in embodiments the radiation receiver has to be moved in two directions over the molding in either one direction only or for a complete scan of the molding.

While it is conceivable to use an imaging system of mirror or lens optics for the electromagnetic radiation in the THz frequency range to produce the image of the fibers, in one embodiment of the invention a synthetic imaging technique is used to produce the image of the fibers.

The principle of synthetic imaging, which is often referred to as synthetic aperture imaging, is to take the snapshot of an antenna or large aperture lens through a plurality of temporally successive shots of a moving or small aperture lens to replace a plurality of temporally successive recordings of a plurality of fixed antennas or stationary lenses with a small aperture. The best-known synthetic imaging system is the so-called Synthetic Aperture Radar (SAR for short). In this case, the transmitting and the receiving antenna of a radar system, which is mounted for example on an aircraft, moved past an object. In the course of this movement, the object is radiated from a variable angle and recorded accordingly. If the path of the transmitting and receiving antenna is sufficiently well-known, the aperture of a large antenna can be synthesized from the intensity and phase position of the radio-frequency signal emitted by the transmitting antenna and reflected by the object back into the receiving antenna, thus achieving high spatial resolution in the direction of movement of the antenna. With the aid of the recorded data of the reflected radar signal, a separate synthetic antenna or a synthetic one is generated for each location illuminated by the transmitting antenna in the course of the flyby Objectively calculated, whose angular resolution in the AC mode is selected so that the geometric resolution in the direction of flight or movement is the same for all the distances considered.

For a stationary application, as described in this application, a plurality of radiation sources and radiation receivers are used in an embodiment of the method according to the invention, which image the fibers at different angles and their signals are evaluated according to the SAR principle. In order to obtain the best possible spatial resolution, in one embodiment the signal emitted by a single radiation source is received by a plurality of radiation receivers.

In order to distinguish the signals emitted by the individual radiation sources after their reflection from the fibers or their transmission through the fibers when received by a plurality of radiation receivers, in one embodiment the individual radiation sources radiate their signals, which all have the same frequency, in time one after the other. This means that the signal emission from the individual transmitters takes place serially. In this method, the signal received at a radiation receiver can be unambiguously assigned to a radiation source at any time.

Alternatively, in one embodiment, all the radiation sources can be simultaneously, i. parallel in time, emit their signals, each radiation source emitting a signal at a different frequency. In this way, the signals of each radiation source are frequency-encoded. Since, in such an embodiment, there are no two radiation sources of identical frequency of the respective radiated electromagnetic signal, each signal received by a receiver is uniquely assignable to a single radiation source. In the context of such an embodiment, the frequency of the electromagnetic signals is their carrier frequency and not their modulation frequency.

In one embodiment, therefore, to generate the image of the fibers by means of electromagnetic radiation in the THz frequency range, a method is used comprising the steps of emitting a first electromagnetic signal having a first frequency from a first radiation source, emitting at least a second electromagnetic signal to a second one Frequency from a second radiation source, wherein the first and the second frequency are different from each other, and substantially simultaneously receiving the first signal and the second signal with a first receiver and substantially simultaneously receiving the first signal and the second signal with at least one second receiver , In this case, the method according to the invention is not restricted to the emission and the reception of two signals, but in one embodiment of the invention more than two signals are emitted and received.

In such an embodiment, each of the spatially separated radiation receivers receives simultaneously a first signal from a first radiation source and a second signal from a second radiation source, wherein the first and the second radiation source are arranged at separate locations, then the received signals can be generated in a short time a large aperture is synthesized and a high resolution image is calculated.

In particular, in one embodiment, a method is conceivable in which the generation of the image of the fibers takes place with an arrangement with a long working distance between the radiation source and the radiation receiver. In this way, an image of the fibers can be generated, for example, from the hall ceiling of a production plant for fiber-reinforced molded parts.

Further advantages, features and applications of the present invention will become apparent from the following description of embodiments and the associated figures.

1 shows the basic structure of a device used for the inventive method for producing an image of the fibers.

2 shows schematically the structure for generating an image of the fibers in a first embodiment of the method according to the invention.

3 schematically shows a structure for generating an image according to a second embodiment of the method according to the invention.

4 schematically shows a structure for generating an image according to another embodiment of the method according to the invention.

In the 1 to 4 identical elements are identified by identical reference numerals.

The imaging device off 1 has a radiation source 1 for generating electromagnetic radiation 2 in the THz frequency range, here around 250 GHz. In order to make a distance measurement, the frequency of the radiation source 1 generated and radiated electromagnetic radiation 2 varies continuously, as shown by the diagram 3 in the radiation source 1 (Plotted is the radiated frequency over time) is indicated. That is, the frequency is changed continuously with time, the rate of frequency change being constant.

The of the radiation source 1 generated radiation is emitted and on the object to be detected, here a plurality of layers of fiber mats 4 , steered.

The fibers to be inspected 4 Back-reflected radiation is detected by means of a radiation receiver 5 detected. This is the radiation receiver 5 a coherent radiation receiver, ie in the radiation receiver 5 becomes the detected radiation 6 with one from the source 1 originating reference signal 7 mixed and generates a signal with the difference frequency between the generated at a defined time THz signal and the THz signal detected at this defined time. The reference signal 7 reflects the current from the radiation source 1 radiated frequency of electromagnetic radiation.

Since the time of generation or radiation of the electromagnetic radiation 2 from the radiation source 1 thus frequency-coded, can be the duration of the electromagnetic radiation 2 between the radiation source 1 , the fibers 4 and the radiation receiver 5 Immediately determine if the difference frequency between the current from the radiation source 1 radiated signal and the same time defined by the radiation receiver 5 detected signal is known. As the radiation receiver 5 by mixing the reference signal 7 and the detected signal 6 This generates a signal with the difference frequency. The distance r between the radiation receiver 5 and the sensing fibers 4 then calculates on the assumption that the radiation source 1 and the radiation receiver 5 the same distance from the fibers 4 have, as r = c / 2Δt = c / 2Δf / df / dt , where c is the speed of light and t is the time required for the electromagnetic radiation generated and radiated by the radiation source to travel back and forth at the speed of light the distance r to the reflected object.

In the illustrated embodiment, the radiation source 1 a bandwidth of the generated and radiated electromagnetic radiation in a range of 230 GHz to 320 GHz, wherein the frequency is changed at a constant rate, so that the range of 230 GHZ to 320 GHZ in 100 μs is tuned.

Based on 2 Now, a first embodiment of the method according to the invention will be described, wherein an apparatus is used to generate the image of the fibers, as schematically with reference to 1 has been described.

For the production of moldings, here a wind turbine wing made of glass fiber reinforced epoxy resin, glass fiber mats are first 4 in a mold 9 inserted. The fiberglass mats 4 are in the illustrated embodiment of the method according to the invention fabric with warp and weft threads, so that the glass fibers of a layer 4a . 4b . 4c , ... at least extend in two perpendicular directions to each other. To achieve the necessary strength of the component, there are several layers 4a . 4b . 4c , ... in the shape 9 arranged one above the other.

Currently, the individual layers of fiber fabrics 4a . 4b . 4c , ... by hand in the form 9 inserted. However, it can not be ruled out that this placement or insertion of the fibers into the mold will be automated in the future.

In the schematic in the 2 to 4 The illustrated method of manufacturing a wind turbine blade becomes the mold 9 before inserting the glass fiber mats 4a . 4b . 4c , ... coated with a release agent to allow easy demolding of the finished molding after curing of the matrix.

The textile, ie woven glass fiber mats 4a . 4b . 4c have the advantage that they are highly flexible and so the inner wall 10 the form 9 adjust and follow their course. When inserting the fiberglass fabric 4a . 4b . 4c However, it often comes to blemishes.

It is in 2 as well as in the following 3 and 4 the most common type of defect is 8. This is a wave or ondulation in a part of the layers of glass fiber fabrics 4a . 4b . 4c , ... Due to the high flexibility of each fiberglass fabric 4a . 4b . 4c , ... are such waves with the naked eye after inserting all tissues 4a . 4b . 4c into the mold 9 no longer recognizable as the wave 8th usually covered as shown by other tissues.

Therefore, after inserting the tissue 4a . 4b . 4c into the mold 9 an image of the fibers with the help of electromagnetic radiation 2 generated in the THz frequency range, which makes it possible, due to the inherent properties of the electromagnetic radiation in this frequency range, in the area between the uppermost fiber fabric 4a and the shape 9 to look in and the flaw 8th to recognize.

Will such a fault 8th in that with the arrangement of radiation source 1 and radiation receiver 5 detected image, this fault can by re-inserting or smoothing the fiber mats 4a . 4b . 4c , ... Getting corrected. It is crucial that the recording of the image of the fibers takes place before they are impregnated with a matrix material, in the illustrated embodiment, epoxy resin.

After inserting the fiberglass fabric 4 , generating the image and optionally correcting the position of the glass fiber fabrics 4 , a release fabric is placed on the fibers, followed by a dispensing medium and an air impermeable film, ie a vacuum film (not shown in the figures). While release fabric and the distribution medium ensure that this is in the mold 9 As the inflowing matrix material is better distributed in the mold and so that the fibers soak more uniformly, the film is sealed airtight at its edges with the edges of the mold. Next, the shape or volume between the film and the surface 10 the form 9 , A vacuum is applied, whereby the glass fiber mats are pressed against the mold and the matrix material is sucked into the mold after opening a corresponding inflow channel.

Are the fiber mats 4 soaked evenly with matrix material, so let the molding harden.

In a further step, after curing and removal of the molding from the mold 9 this optionally be checked again with the aid of electromagnetic radiation in the THz frequency range, for which purpose an image of the fibers, but now embedded in the matrix material is taken and the image is subsequently examined for flaws, eg delaminations.

In the embodiment of 2 the image of the fibers is picked up from the side of the mold. Therefore, the form 9 in the in 2 illustrated embodiment made of polypropylene, which is largely transparent to the electromagnetic radiation used, so that they form a view of the fibers 4 allows.

The 3 and 4 describe in principle the same process flow as in connection with 2 previously described. That's why the shape is the same 9 whose surface 10 , the radiation source 1 as well as the radiation receiver 5 denoted by the same reference numerals.

However, the show 3 and 4 deviating from the illustration 2 , other points of view on the glass fibers 4 ,

In 3 the picture is taken as well as in the illustration 2 in a reflection arrangement, but here from the open side of the mold 9 ago. In this way, after inserting the glass fibers 4 into the mold 9 no further material between the radiation source 1 or the radiation receiver 5 and the glass fibers 4 ,

4 shows an arrangement of the radiation source 1 and the radiation receiver 5 in transmission geometry, ie the electromagnetic radiation 2 in the THz frequency range occurs from the radiation source 1 initially by the transparent shape for this frequency range 9 through, through the fiberglass fabric 4a . 4b . 4c , ... and only then reaches the radiation receiver 5 ,

For purposes of the original disclosure, it is to be understood that all such features as will become apparent to those skilled in the art from the present description, drawings, and claims, even if concretely described only in connection with certain other features, both individually and separately any combination with other of the features or feature groups disclosed herein are combinable, unless this has been expressly excluded or technical conditions make such combinations impossible or pointless. For the sake of brevity and readability of the description, the comprehensive, explicit representation of all conceivable combinations of features is omitted here.

While the invention has been illustrated and described in detail in the drawings and the foregoing description, such illustration and description is exemplary only and is not intended to limit the scope of the protection as defined by the claims. The invention is not limited to the disclosed embodiments.

Variations of the disclosed embodiments will be apparent to those skilled in the art from the drawings, the description and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain features are claimed in different claims does not exclude their combination. Reference signs in the claims are not intended to limit the scope of protection.

LIST OF REFERENCE NUMBERS

1

 radiation source

2

 electromagnetic radiation

3

 diagram

4

 glass fibers

4a

 glass fabric

4b

 glass fabric

4c

 glass fabric

5

 radiation receiver

6

 detected signal

7

 reference signal

8th

 fault location

9

 shape

10

 surface

Claims (15)

Process for producing fiber-reinforced molded parts comprising the steps of providing a mold ( 9 ) for the molded part to be produced, laying a plurality of fibers ( 4 ) on the shape ( 9 ), Irradiating the fibers ( 4 ) with electromagnetic radiation ( 2 ) in the THz frequency range, detecting the of the fibers ( 4 ) reflected electromagnetic radiation ( 2 ) and / or through the fibers ( 4 ) transmitted electromagnetic radiation ( 2 ), Identifying a fault ( 8th ) of the fibers ( 4 ) on the basis of the fibers ( 4 ) reflected electromagnetic radiation ( 2 ) and / or through the fibers ( 4 ) transmitted electromagnetic radiation ( 2 ) if an error location ( 8th ) of the fibers ( 4 ), correcting the fault ( 8th ), and impregnating the fibers ( 4 ) with a matrix material. Method according to claim 1, characterized in that the fibers ( 4 ), Glass fibers and the matrix material is a plastic. Method according to claim 1 or 2, characterized in that the fibers ( 4 ) in the form of a fabric or fabric ( 4a . 4b . 4c , ...) on the shape ( 9 ). Method according to one of claims 1 to 3, characterized in that the fibers ( 4 ) in layers on the mold ( 9 ), wherein at least a first layer of fibers ( 4a . 4b . 4c , ...) on the shape ( 9 ), the fibers ( 4 ) with electromagnetic radiation ( 2 ) are irradiated in the THz frequency range emitted by the fibers ( 4 ) reflected electromagnetic radiation ( 2 ) and / or through the fibers ( 4 ) transmitted electromagnetic radiation ( 2 ), an error location ( 8th ) of the fibers ( 4a . 4b . 4c , ...) on the basis of the fibers ( 4 ) reflected electromagnetic radiation ( 2 ) and / or through the fibers ( 4 ) transmitted electromagnetic radiation ( 2 ) is identified if an error location ( 8th ) of the fibers is identified, the fault location ( 8th ), at least one further layer of fibers ( 4a . 4b . 4c , ...) on the first layer of fibers ( 4 ), the fibers ( 4 ) with electromagnetic radiation ( 2 ) are irradiated in the THz frequency range emitted by the fibers ( 4 ) reflected electromagnetic radiation ( 2 ) and / or through the fibers ( 4 ) transmitted electromagnetic radiation ( 2 ), an error location ( 8th ) of the fibers ( 4 ) on the basis of the fibers ( 4 ) reflected electromagnetic radiation ( 2 ) and / or through the fibers ( 4 ) transmitted electromagnetic radiation ( 2 ) and if an error location ( 8th ) of the fibers is identified, the fault location ( 8th ) is corrected. Method according to one of claims 1 to 4, characterized in that the steps of irradiating the fibers ( 4 ) with electromagnetic radiation ( 2 ) in the THz frequency range and the detection of the fibers ( 4 ) reflected electromagnetic radiation ( 2 ) and / or through the fibers ( 4 ) transmitted electromagnetic radiation ( 2 ), the following steps include generating electromagnetic radiation ( 2 ) in the THz frequency range with a radiation source ( 1 ), Directing the electromagnetic radiation ( 2 ) on the fibers ( 4 ), Detecting the of the fibers ( 4 ) reflected electromagnetic radiation ( 2 ) with a radiation receiver ( 5 ) and / or detecting the through the fibers ( 4 ) transmitted electromagnetic radiation ( 2 ) with a radiation receiver ( 5 ). Method according to one of claims 1 to 5, characterized in that the shape ( 9 ) from one for the electromagnetic radiation ( 2 ) in the THz frequency range transparent material. Method according to one of claims 1 to 6, characterized in that the step of impregnation comprises the following steps laying a film on the fibers ( 4 ), Sealing the foil against the mold ( 9 ), Evacuating a volume between the film and the mold ( 9 ) and introducing liquid matrix material into the volume between the foil and the mold ( 9 ). Method according to one of claims 1 to 7, characterized in that the film from a for the electromagnetic radiation ( 2 ) in the THz frequency range transparent material. Method according to one of claims 1 to 8, characterized in that the molded part is a wing for a wind turbine. Method according to one of claims 1 to 9, characterized in that the molding is cured, wherein after curing, the molding with electromagnetic radiation ( 2 ) is irradiated in the THz frequency range emitted by the fibers ( 4 ) reflected electromagnetic radiation ( 2 ) and/ or through the fibers ( 4 ) transmitted electromagnetic radiation ( 2 ) is detected and a fault of the molded part is identified. Method according to one of claims 5 to 10, characterized in that the steps of generating electromagnetic radiation ( 2 ) in the THz frequency range with the radiation source ( 1 ) and detecting the fibers ( 4 ) reflected electromagnetic radiation ( 2 ) with the radiation receiver ( 5 ) and / or grasping through the fibers ( 4 ) transmitted electromagnetic radiation ( 2 ) with the radiation receiver ( 5 ) to be done with RADAR. Method according to one of claims 5 to 11, characterized in that the generation of electromagnetic radiation ( 2 ) in the THz frequency range with the radiation source ( 1 ) and the detection of the fibers ( 4 ) reflected electromagnetic radiation ( 2 ) with the radiation receiver ( 5 ) and / or detecting the through the fibers ( 4 ) transmitted electromagnetic radiation ( 2 ) with the radiation receiver ( 5 ) in the form of a transit time measurement of the electromagnetic radiation ( 2 ) between the radiation source ( 1 ) and the radiation receiver ( 5 ) respectively. Method according to one of claims 5 to 12, characterized in that the step of generating electromagnetic radiation ( 2 ) in the THz frequency range with the radiation source ( 1 ) a frequency modulation of the electromagnetic radiation ( 2 ), wherein the change in frequency is preferably constant over time, and in that the step of detecting the electromagnetic radiation ( 2 ) with the radiation receiver ( 5 ) a determination of a difference frequency between a reference signal ( 7 ) and the electromagnetic radiation received by the radiation receiver ( 2 ) and wherein from the difference frequency the transit time of the electromagnetic radiation ( 2 ) between the radiation source ( 1 ) and the radiation receiver ( 5 ) is calculated. Method according to one of claims 1 to 13, characterized in that the radiation source ( 1 ) and / or the radiation receiver ( 5 ) relative to the fibers ( 4 ) is moved. Method according to one of claims 1 to 14, characterized in that the steps of irradiating the fibers ( 4 ) with electromagnetic radiation ( 2 ) in the THz frequency range and the detection of the fibers ( 4 ) reflected electromagnetic radiation ( 2 ) and / or through the fibers ( 4 ) transmitted electromagnetic radiation ( 2 ) at a plurality of locations of the fibers ( 4 ) and so a picture of the fibers ( 4 ) is produced.

Images