WO2012171971A1

WO2012171971A1 - Method for producing fibre-reinforced moulded parts

Info

Publication number: WO2012171971A1
Application number: PCT/EP2012/061230
Authority: WO
Inventors: Torsten LÖFFLER; Holger Quast
Original assignee: Synview Gmbh
Priority date: 2011-06-15
Filing date: 2012-06-13
Publication date: 2012-12-20
Also published as: DE102011051071A1

Abstract

A method for producing fibre-reinforced moulded parts that makes it possible to check the fibres (4) for their correct position in a mould for such a moulded part before the fibres (4) are impregnated with the matrix material. The method for producing fibre-reinforced moulded parts comprises the steps of providing a mould (9) for the moulded part to be produced, placing a plurality of fibres (4) onto the mould (9), irradiating the fibres (4) with electromagnetic radiation (2) in the THz frequency range, detecting the electromagnetic radiation (2) that is reflected by the fibres (4) and/or the electromagnetic radiation (2) that is transmitted through the fibres (4), identifying a flaw (8) of the fibres (4) on the basis of the electromagnetic radiation (2) reflected by the fibres (4) and/or the electromagnetic radiation (2) transmitted through the fibres (4), correcting any flaw (8) of the fibres (4) that is identified, and impregnating the fibres (4) with a matrix material.

Description

Process for producing fiber-reinforced molded parts

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 compared to form identical parts without fiber reinforcement significantly improved strength. In other words, in order to achieve even strength values with conventional materials, significantly larger quantities of material are needed, 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 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.

5

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. Festigkeit θ 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 check is time consuming and, since the fibers are mostly arranged in a plurality of layers, only the topmost or a few layers

15 of the fibers capture.

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 a weakening of a molded article after embedding 10 of the fibers in the matrix and subsequent 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 molded part prior to impregnation of the fibers with the matrix material to its correct position.

Prior to this invention, a process for the production of fiber-reinforced molded parts is proposed according to the invention, comprising the steps of providing a mold for the molded article to be produced.

S0, applying a plurality of fibers to the mold, irradiating the fibers with electromagnetic radiation in the THz frequency range, detecting the electromagnetic radiation reflected by the fibers and / or the electromagnetic radiation transmitted through the fibers, identifying a fault location of the fibers on the basis of electromagnetic radiation reflected by the fibers and / or the electromagnetic radiation transmitted through the fibers.

5 see radiation 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, particularly plastics, are susceptible to electromagnetic radiation in this frequency range. In contrast to the X-radiation, the electromagnetic radiation in the THz frequency range is not ionizing.

The process according to the invention for the production of glass-fiber-reinforced plastics is particularly expedient, the reinforcing fibers being glass fibers and the matrix material being 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 inventive method is also suitable for producing fiber-reinforced molded parts mit 5 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 replace the fibers applied to the mold with a matrix material or to correct their position in the mold before they have been soaked in the fibers. This is understood in the sense of the present application as correcting a fault.

While identifying a fault location of the fibers, i. E. 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 carry out 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, d .h. 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.

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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. It is useful in one embodiment, if in a first step at least one layer of fibers on the Form are applied, the position of fibers is irradiated with electromagnetic radiation in the THz frequency range and is detected by the fibers reflected or transmitted by the radiation radiation, a fault of the fibers on the basis of the fibers reflected or transmitted through the fibers radiation is identified and if a fault of the

5 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 the fibers reflected or transmitted by this transmitted radiation, an error location of the fibers is identified by the fibers reflected or by the fibers transmit-ίθ radiation and if a fault of the fibers is identified, the fault 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 [5 of all layers of fibers together.

In one 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.

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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.

SO 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 electri-

! 5 magnetic radiation in the THz frequency range directed from the outside to the fibers and detects the reflected electromagnetic radiation from the fibers with a radiation receiver. In alternative embodiments, which are particularly suitable for producing more complex shaped parts, the shape of an at least partially concave body is 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 the irradiation and the detection of the reflected or transmitted radiation can take place in reflection or transmission geometry, the electromagnetic radiation passing through the shape passes through. 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 15 and radiation receiver below the mold, while leaving free space to work above the mold.

In a further embodiment of the method according to the invention, the step of impregnating the fibers with a matrix material comprises placing a film on the fibers, sealing the film against the mold, evacuating a volume between the film and the mold and inserting of liquid matrix material in the volume between the film 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 hardened 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 exposed to electromagnetic radiation in the THz range. Frequency range is irradiated and is detected by the molded part or detected by this transmitted- radiation.

On the basis of such a measurement and, where appropriate, image formation of the finished molded article, delaminations, i. E. Detachment of the matrix from the fibers in the finished molded 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 ί θ of the detected radiation.

Basically, for a transit time or travel measurement of the electromagnetic radiation between the radiation source and the radiation receiver, three mutually exclusive methods are available which all provide the same information about the distance between the object to be tested and the radiation source or the radiation receiver deliver:

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 a determination of the difference frequency between a reference signal and the electromagnetic radiation received by the radiation receiver comprises 15 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 point of the radiation 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 5 in the THz frequency range and the radiation received at the defined time interval by the radiation receiver, in one embodiment a coherent detection takes place at the radiation receiver of the a reference signal from the radiation source is mixed 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 Af between the frequency of the to a defined

Calculate the time of the electromagnetic radiation generated by the radiation source and the detected at the defined time in the radiation receiver electromagnetic radiation:

where c is the speed of light and ί 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 with the distance r to the reflecting object, here the fibers. The ratio df I dt denotes the rate of change with which the frequency / the generated and radiated electromagnetic radiation is changed over the time t. This is also called Chirprate.

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As an alternative 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 electromagnetic radiation that is pulse-shaped in the time domain. The duration of a pulse with a short pulse duration compared to the distance to be detected can be easily determined. 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 one after another, 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 relative

! 5 phase angles of the individual radiation components with a plurality of different frequencies can also be the running time or the path between the radiation source, fibers and radiation receiver uniquely determined.

In embodiments of the method according to the invention, the radiation source and / or the radiation receiver are 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 the form of a cell or a matrix.

Depending on the number of image points and their arrangement in the radiation receiver, in embodiments the radiation receiver has to be moved over the molding in two directions either in one direction only or for a full 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 generate the image of the fibers, in one embodiment of the invention a method of synthetic imaging is used to produce the image Used 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 objective through a plurality of temporally successive images of a tilted or small aperture lens or to replace it with 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 receiving antennas of a radar system, which is for example mounted on an aircraft S0, are 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 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, and thus a high local resolution in the direction of movement the antenna can be achieved. With the aid of the recorded data of the reflected radar signal, a separate synthetic antenna or a synthetic objective is calculated for each location illuminated by the transmitting antenna in the course of the flyby. net whose angular resolution in 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, such as that described in this application, in one embodiment of the method according to the invention a multiplicity of beam sources and radiation receivers are used, which image the fibers at different angles and their signals evaluated according to the SAR principle. In order to obtain the best possible spatial resolution, in one embodiment the signal radiated by a single radiation source is received by a plurality of radiation receivers.

10

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 [5 consecutive. 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. In parallel, they emit their signals, each 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 with identical frequency of the respectively emitted electromagnetic signal, each signal received by a receiver can be clearly assigned to a single radiation source. In terms 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 with the aid of electromagnetic radiation in the THz frequency range, a method with the following steps is used.

S0 det: emitting a first electromagnetic signal having a first frequency from a first radiation source, emitting at least a second electromagnetic signal having a second frequency from a second radiation source, the first and second frequencies being different from each other, and substantially simultaneously receiving the first signal and the second signal with a first receiver and substantially simultaneous

! 5 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 limited to the emission and the reception of two signals, but in one embodiment of the invention more than two signals are emitted and received. If, in such an embodiment, each of the spatially separated radiation receivers simultaneously receives a first signal from a first radiation source and a second signal from a second radiation source, the first and second radiation sources being disposed at mutually separate locations, then the received signals can synthesizes a large aperture in a short time and calculates a high-resolution image.

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 ίθ 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.

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

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

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

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

SO In FIGS. 1 to 4, identical elements are identified by identical reference numerals.

The imaging apparatus of FIG. 1 has a radiation source 1 for generating electromagnetic radiation 2 in the THz frequency range, in this case around 250 GHz. In order to be able to make a distance measurement, the frequency of the electromagnetic radiation 2 emitted and emitted by the radiation source 1 is continuously varied, as indicated by the diagram 3 in the radiation source 1 (plotted is the radiated frequency over time). That is, the frequency is changed continuously with time, the rate of frequency change being constant. The radiation generated by the radiation source 1 is radiated and directed to the object to be detected, here a plurality of layers of fiber mats 4.

5 The radiation reflected back from the fibers 4 to be inspected is detected by means of a radiation receiver 5. In this case, the radiation receiver 5 is a coherent radiation receiver, i. In the radiation receiver 5, the detected radiation 6 is mixed with a reference signal 7 originating from the source 1 and a signal with the difference frequency between the THz signal generated at a defined time and the THz signal detected at this defined instant is generated. The reference signal 7 reflects the currently emitted by the radiation source 1 frequency of the electromagnetic radiation.

Since the time of generation or radiation of the electromagnetic radiation 2 from the Strahl5 radiation source 1 is thus frequency-coded, the transit time of the electromagnetic radiation 2 between the radiation source 1, the fibers 4 and the radiation receiver 5 can be determined directly, if the difference frequency between the current is known from the radiation source 1 emitted signal and at the same defined time detected by the radiation receiver 5 signal. Since the radiation receiver 5 generates a signal with the difference frequency by mixing the reference signal 7 and the detected signal 6, this is given. The distance r between the radiation receiver 5 and the detecting fibers 4 is calculated on the assumption that the radiation source 1 and the radiation receiver 5 are equidistant from the fibers 4, as r =, where c is the speed of light and ί is the time which are those of the

Radiation source generated and radiated electromagnetic radiation needed to travel at the speed of light, the distance r to the reflected object and back.

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

320 GHZ in 100 [is tuned.

A first embodiment of the method according to the invention will now be described with reference to FIG. 2, wherein an apparatus as described schematically with reference to FIG. 1 is used to produce the image of the fibers. For the production of moldings, here a wind turbine blades made of glass fiber reinforced epoxy resin, glass fiber mats 4 are first inserted into a mold 9. The glass fiber 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 a layer 4a, 4b, 4c, ... at least extend in two perpendicular directions 5 to each other. In order to achieve the necessary strength of the component, a plurality of layers 4a, 4b, 4c, ... in the mold 9 are arranged one above the other.

Currently, the individual layers of fiber fabrics 4a, 4b, 4c, ... inserted by hand in the mold 9. However, it is not excluded that this laying on or inserting the fibers in ίθ the form will be automated in the future.

In the method shown schematically in FIGS. 2 to 4 for producing a wind turbine blade, the mold 9 is coated with a release agent prior to insertion of the glass fiber mats 4a, 4b, 4c,..., In order to easily demold the finished molded body after the To allow matrix.

The textile, i. woven glass fiber mats 4a, 4b, 4c have the advantage that they are highly flexible and so adapt to the inner wall 10 of the mold 9 and follow its course. When inserting the glass fiber fabric 4a, 4b, 4c, however, it is not uncommon for flaws.

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In this case, in FIG. 2 as well as in the following FIGS. 3 and 4, the most frequently occurring type of fault location is designated by 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 the individual glass fiber fabrics 4a, 4b, 4c, ... are such waves with the naked eye after Einle - 15 gene all tissues 4a, 4b, 4c in the mold 9 no longer recognizable, since the shaft 8 is usually covered as shown by other tissues.

Therefore, after inserting the fabrics 4a, 4b, 4c into the mold 9, an image of the fibers is generated by means of electromagnetic radiation 2 in the THz frequency range which, due to the inherent properties of the electromagnetic radiation in this frequency range, allows the Looking in area between the uppermost fiber fabric 4a and the mold 9 and to recognize the fault point 8.

If such an error location 8 is detected in the image generated by the arrangement of radiation source 1 and radiation receiver 5, then this defect location can be corrected by reinserting or smoothing out the fiber mats 4a, 4b, 4c,... 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 glass fiber fabrics 4, forming 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 in Figure 5). While the release fabric and the distribution medium ensure that the matrix material flowing into the mold 9 is better distributed in the mold and so that the fibers soak more uniformly, the film is airtightly sealed at its edges with the edges of the mold. Next, a vacuum is applied to the mold or volume between the film and the surface 10 of the mold 9, 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.

If the fiber mats 4 are soaked evenly with matrix material, then the shaped body is allowed to harden.

In a further step, after the curing and demoulding of the molded part from the mold 9, it can 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 below on fault locations, eg Delaminations, is being investigated.

In the embodiment of Figure 2, the image of the fibers is taken from the side of the mold. Therefore, the mold 9 is made in the embodiment shown in Figure 2 of polypropylene, which is largely transparent to the electromagnetic radiation used, 15 so that this allows a shape-side view of the fibers 4.

Figures 3 and 4 describe in principle the same process flow as in connection with Figure 2 described above. Therefore, the shape 9, the surface 10, the radiation source 1 and the radiation receiver 5 are denoted by the same reference numerals.

SO

However, FIGS. 3 and 4 deviating from the illustration from FIG. 2 show different directions of view of the glass fibers 4.

In Figure 3, the image is taken as well as in the illustration of Figure 2 in a frost flexionsanordnung, but here from the open side of the mold 9 forth. In this way, after inserting the glass fibers 4 into the mold 9, there is no further material between the radiation source 1 or the radiation receiver 5 and the glass fibers 4. FIG. 4 shows an arrangement of the radiation source 1 and of the radiation receiver 5 in transmission geometry, ie the electromagnetic radiation 2 in the THz frequency range first emerges from the radiation source 1 and thus transmits the transparent form 9 for this frequency range, ie through the glass fiber fabrics 4a, 4b, 4c,. , , Only then does it reach 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 though concretely described only in connection with certain other features, both individually and separately can also be combined in any combinations with other features or feature groups disclosed herein, 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 presentation of all conceivable combinations of features is omitted here.

While the invention has been shown and described in detail in the drawings and the foregoing description, this description and description is given by way of example only and is not intended to limit the scope of the invention as defined by the claims. The invention is not limited to the disclosed embodiments.

Modifications 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 is exclusive their combination is not a reference numerals in the claims are not intended as a restriction of the scope.

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

8 error location

9 form

10 surface

Claims

P a n t a n s p r e c h e

Process for producing fiber-reinforced molded parts by the steps

Providing a mold (9) for the molded part to be produced,

Placing a plurality of fibers (4) on the mold (9),

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) of the fibers (4) on the basis of the electromagnetic radiation (2) reflected by the fibers (4) and / or the electromagnetic radiation (2) transmitted through the fibers (4),

if an error location (8) of the fibers (4) is identified, correcting the error location (8), and

Impregnating the fibers (4) with a matrix material.

A method according to claim 1, characterized in that the fibers (4) are glass fibers and the matrix material is a plastic.

A method according to claim 1 or 2, characterized in that the fibers (4) in the form of a fabric or fabric (4a, 4b, 4c, ...) are placed on the mold (9).

Method according to one of claims 1 to 3, characterized in that the fibers (4) are placed in layers on the mold (9), wherein at least a first layer of fibers (4a, 4b, 4c, ...) on the mold (9) is applied, the fibers (4) are irradiated with electromagnetic radiation (2) in the THz frequency range, the electromagnetic radiation (2) reflected by the fibers (4) and / or the electromagnetic radiation transmitted through the fibers (4) (2), an error location (8) of the fibers (4a, 4b, 4c,...) Based on the electromagnetic radiation (2) reflected by the fibers (4) and / or the electromagnetic energy transmitted through the fibers (4) Radiation (2) is identified, if a defect (8) of the fibers is identified, the defect (8) is corrected, at least one further layer of fibers (4a, 4b, 4c, ...) on the first layer of fibers ( 4) is placed, the fibers (4) with electromagnetic radiation (2) in the THz frequency range be are irradiated, the electromagnetic radiation (2) reflected by the fibers (4) and / or the electromagnetic radiation (2) transmitted through the fibers (4) is detected, an error location (8) 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) is identified and if a fault location (8) of the fibers is identified, the fault location (8) 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 detecting the electromagnetic radiation (2) reflected by the fibers (4) and / / or the electromagnetic radiation (2) transmitted through the fibers (4), comprise the following steps

Generating electromagnetic radiation (2) in the THz frequency range with a radiation source (1),

Directing the electromagnetic radiation (2) onto the fibers (4),

Detecting the electromagnetic radiation (2) reflected by the fibers (4) with a radiation receiver (5) and / or

Detecting the by 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 mold (9) consists of a 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

Placing 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 consists of 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 molded part is cured, wherein after curing, the molded article is irradiated with electromagnetic radiation (2) in the THz frequency range, the electric (4) reflected by the fibers (4). is detected by the electromagnetic radiation (2) and / or the electromagnetic radiation (2) transmitted through the fibers (4) and a fault location 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 the detection of the fibers (4) reflected electromagnetic radiation (2) the radiation receiver (5) and / or the detection of the electromagnetic radiation (2) transmitted through the fibers (4) to the radiation receiver (5) are carried out so that they take place with RADAR.

Method according to one of claims 5 to 1 1, 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 the detection of the fibers (4) transmitted by the 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) comprises a frequency modulation of the electromagnetic radiation (2), wherein the change of the frequency is preferably constant with respect to time, and in that the step of detecting the electromagnetic radiation (2) with the radiation receiver (5) comprises determining a difference frequency between a reference signal (7) and the electromagnetic radiation (2) received by the radiation receiver; the difference frequency, the duration 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) is moved relative to the fibers (4).

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 detecting the electromagnetic radiation (2) reflected by the fibers (4) and / / or the electromagnetic radiation transmitted through the fibers (4). Radiation (2) takes place at a plurality of locations of the fibers (4) and so an image of the fibers (4) is generated.