Mold and method for manufacturing a fiber composite component

Abstract

The invention relates to a mold for producing a fiber composite component from a fiber composite material, comprising a fiber material and a matrix material embedding the fiber material, with at least one forming tool surface made of a metallic material, and with a monitoring device having at least one ultrasonic sensor acoustically connected to the mold, wherein the ultrasonic sensor is configured to emit ultrasonic signals into the component produced on the forming tool surface and / or to receive the ultrasonic signals reflected from the component, characterized in that at least one recess is provided in the at least one forming tool surface, into which a mold insert is inserted such that one side of the insert forms part of this forming tool surface.wherein the at least one ultrasonic sensor is acoustically connected to the mold insert and the mold insert is made of a material different from the metallic material of the molding tool surface.

Description

[0001] The invention relates to a forming tool for producing a fiber composite component from a fiber composite material comprising a fiber material and a matrix material embedding the fiber material, with a forming tool surface made of a metallic material, and with a monitoring device having at least one ultrasonic sensor acoustically connected to the forming tool, wherein the ultrasonic sensor is configured to emit ultrasonic signals into the component produced on the forming tool surface and to receive the ultrasonic signals reflected from the component.

[0002] The invention also relates to a method for this.

[0003] Due to the high strength-to-weight ratio and stiffness of fiber-reinforced composite components, these materials are now indispensable in the aerospace and automotive industries. The production of large-scale rotor blades, for example for wind turbines, is also possible and practical using fiber-reinforced composites. In the manufacturing process of a fiber-reinforced composite component, a matrix material infused into a fiber material is typically cured or consolidated under temperature and pressure, forming an integral unit with the fiber material after curing. This process forces the reinforcing fibers of the fiber material into the desired orientation, enabling them to transfer the applied loads in the specified direction.

[0004] Fiber-reinforced composites, from which fiber-reinforced composite components are manufactured, generally have two main components: a fiber material and a matrix material. Additional secondary components can also be used, such as binder materials or additional functional elements that are to be integrated into the component.

[0005] In addition to dry fiber materials, which require infusion with the matrix material after the fiber preform has been manufactured, pre-impregnated fiber materials (so-called prepregs) are also used. In these prepregs, the fiber material is already impregnated with the matrix material. A subsequent infusion process is then usually unnecessary. Before the matrix material cures, the fiber material is typically placed in a mold whose surface replicates the shape of the final component.

[0006] These advantageous properties are offset by the disadvantage that the production of fiber composite components is very cost-intensive, as the manufacturing processes cannot always be automated, or in automated processes, increased attention must be paid to quality assurance in order to detect defective components due to process inaccuracies.

[0007] From DE 10 2010 015 027 B1, for example, a fiber laying device is known in which the fibers are laid on the tool by means of fiber laying heads arranged on robots. The robots are guided on a rail system running around the tool, so that any desired position on the tool can be reached by the robots.

[0008] Furthermore, so-called portal systems are known from practice, in which the laying head can be moved over a mostly horizontally arranged forming tool in order to lay the fibers on the forming tool.

[0009] When dry fiber materials are introduced into a mold to form the corresponding fiber preform within the mold, the fiber material must be infused with the matrix material in a further process step, so that the fiber material is ultimately embedded in the matrix material. The infusion process itself is a very critical step in the entire manufacturing process, as only complete impregnation of the fiber material with the matrix material can ensure the necessary component quality. If, however, dry, unimpregnated areas remain within the fiber material, these areas will lead to defects after the matrix material has cured, preventing the intended loads of the component from being transferred as intended.Depending on the size of the unimpregnated areas and the intended use of the fiber composite component, such a component must then be considered as scrap.

[0010] It is therefore desirable to monitor the infusion process as comprehensively as possible in order to detect the formation of dry, unimpregnated areas and to intervene in the infusion process to reduce the risk of such areas forming. This is also desirable for process development and design, in order to gain insights into the process and to improve it precisely (Where are inclusions and thus dry areas likely to occur? Where should the infusion be poured and suctioned off?). The problem here is that the infusion and curing process largely takes place behind closed doors, so that complete process monitoring quickly reaches its limits.

[0011] Ultrasound technology offers one way to monitor the infusion and curing process. Ultrasound waves or signals in the form of acoustic sound waves are emitted into the component and received again after interaction with the component. Based on the received sound waves, the state of the process and the component can then be derived.

[0012] When using ultrasound for process monitoring in the production of fiber composite components, two different variants are generally known: a) the transmission method and b) the pulse-echo method.

[0013] In the through-transmission method, an ultrasonic transducer (usually in the form of a piezoelectric element) is positioned on one side of the component, and an ultrasonic receiver (also usually in the form of a piezoelectric element) is positioned on the opposite side, allowing the transducer to transmit ultrasonic waves into the component. These ultrasonic waves then travel through the component in the thickness direction and are received by the ultrasonic receiver on the other side and forwarded to an evaluation unit. This allows conclusions to be drawn about the flow front and / or the degree of hardening of the matrix material, for example, based on the changing transit time and / or amplitude of the ultrasonic waves or other parameters.

[0014] The through-transmission method is particularly suitable when using closed molds, where the component to be manufactured is usually completely enclosed by the mold. In this case, the ultrasonic transducer and receiver can be coupled to the mold and good results achieved despite the phase transitions between the transducer and the mold, the mold and the component, the component and the mold, and the mold and receiver.

[0015] From DE 197 37 276 C2, for example, a transillumination method for monitoring the curing of thermosets is known, in which a mass contained in a mold is sonicated with ultrasonic waves emitted into the molding mass by a first ultrasonic transducer and then received by a second ultrasonic transducer and evaluated accordingly. Using a reference signal, the difference between the emitted and received signals can be analyzed to monitor the manufacturing process.

[0016] From DE 10 2010 037 849 A1, a transillumination method and a device for manufacturing fiber composite components using an infusion process are further disclosed, in which the transit times of an ultrasound signal through the mold cavity are measured during infiltration and pressure sealing and compared with target values. For this purpose, an ultrasound coupling element is placed on the outer vacuum film, which is connected to an ultrasound probe so that ultrasound signals can be introduced into the mold cavity. By measuring the transit times of ultrasound signals, the manufacturing process, in particular the infiltration and curing processes, can be monitored for quality control purposes.

[0017] From EP 2 657 801 A2, a transmission method for monitoring a manufacturing process in the production of a molded component with a closed mold is known, wherein piezoelectric elements are arranged on opposite sides of the mold without a lead time.

[0018] From DE 10 2016 112 263 A1 a method for producing a fiber composite component using a multi-part mold is known, wherein a plurality of ultrasonic sensors are arranged on each mold part, which provide a corresponding sensor signal and thereby generate a sensor signal profile, from which the cross-sectional geometry in the thickness direction of the flow front of the infused matrix material can then be determined.

[0019] A disadvantage of the through-transmission method, however, is that it is usually not applicable to open-mold processes, as the ultrasonic receiver often cannot be reliably positioned on the open side of the component. In open-mold processes, a mold is provided with a forming surface onto which the fiber material for producing the fiber preform is placed. The fiber preform on the mold is then vacuum-sealed and evacuated to allow for the infusion of the matrix material. On the side of the vacuum setup, which is usually achieved with a thin and highly flexible vacuum film, the ultrasonic receiver (or transducer, depending on the configuration) cannot be reliably positioned. Therefore, the through-transmission method is generally not used in open-mold processes.The transillumination method cannot be used for components or molds with sandwich sections (e.g., a foam core).

[0020] In open mold designs, where the fiber preform is sealed vacuum-tight or airtight under a flexible vacuum setup, as well as in sandwich constructions, the pulse-echo method is often used. An ultrasonic sensor is placed on and coupled to the mold, so that the sensor initially acts as an actuator, introducing ultrasonic signals first into the mold and then into the component. These ultrasonic signals are reflected back to the sensor at the interface of the vacuum setup and received by the sensor. Therefore, the sensor functions as both an ultrasonic transmitter and receiver in this process, acting as both actuator and sensor in one.

[0021] However, when using metallic forming tools made of materials such as aluminum, steel, or corresponding alloys, the pulse-echo method is difficult to implement. Due to the unfavorable reflection coefficient at the interfaces (phase transitions) between the forming tool and the workpiece, a large portion of the sound signal (often more than 90%) is reflected back into the forming tool, and only a small portion is coupled into the workpiece. Within the workpiece, the sound signal is further attenuated, and only a small portion is reflected back to the forming tool. There, due to the high reflection coefficient, only a fraction of the sound signal can couple into the forming tool and ultimately reach the ultrasonic sensor (also called a transducer). Meanwhile, the reflected switching signals in the forming tool decay only slowly, even after numerous reflections, and are superimposed on the sound signals that have passed through the workpiece.

[0022] However, metallic molds are in most cases cost-effective, easy to manufacture, and generally possess high durability and temperature resistance. Therefore, the use of such metallic molds remains the preferred method in practice. Nevertheless, it is also desirable, especially with open mold designs, to implement ultrasonic monitoring during the infusion and curing process to monitor the critical process. The transillumination method has limited applicability, while the pulse-echo method is often too inaccurate when using metallic molds.

[0023] It is therefore an object of the present invention to provide an improved molding tool and an improved method for manufacturing a fiber composite component, with which ultrasonic monitoring, particularly in the pulse-echo method, becomes possible in a process-reliable and accurate manner with open molding tool concepts.

[0024] The problem is solved according to the invention by means of the mold for producing a fiber composite component according to claim 1 and the method for producing a fiber composite component according to claim 9. Advantageous embodiments of the invention are then found in the corresponding dependent claims.

[0025] According to claim 1, a mold for producing a fiber composite component from a fiber composite material is proposed, comprising a fiber material and a matrix material embedding the fiber material, and having at least one forming tool surface made of a metallic material, for example, aluminum, steel, and / or nickel36 (also referred to as INVAR). Furthermore, the mold has a monitoring device comprising at least one ultrasonic sensor acoustically connected to the mold, wherein the ultrasonic sensor is configured to emit ultrasonic signals into the component produced on the forming tool surface and / or to receive the ultrasonic signals reflected from the component.

[0026] Such a generic mold can, for example, be a closed mold with at least two mold halves, each with a shaping surface. After the fiber material has been placed on one of the mold halves and the fiber preform produced, the mold is closed so that the fiber preform is inserted into a cavity formed by the closed mold. This cavity can then be evacuated and, if necessary, infused with matrix material, which is subsequently cured. Both dry and pre-impregnated fiber materials can be used.

[0027] Such a generic mold can also be an open mold, which has a forming tool surface that has a shaping property for at least one side of the fiber composite component to be produced, thus giving the component its final shape, at least on that side. A fiber material, which can be dry or pre-impregnated, is deposited onto this forming tool surface. Subsequently, a vacuum setup is installed on this forming tool surface, sealing the deposited fiber material airtight or vacuum-tight from the environment. Such a vacuum setup typically includes a flexible vacuum cover, usually in the form of a vacuum film, which is spread over the deposited fiber material and sealed against the mold.The component cavity formed under the vacuum cover, containing the fiber material, is then connected to a vacuum pump, allowing the cavity and fiber material to be evacuated. If dry fiber material was used, the matrix material is then infused into the evacuated fiber material to saturate or impregnate it. If pre-impregnated fiber material was used, the infusion process is generally unnecessary. Following this, the matrix material contained within the fiber material is cured, for example, by applying heat and, if necessary, increasing the ambient atmospheric pressure using an autoclave.

[0028] The ultrasonic sensor is essentially a transducer capable of both generating and receiving ultrasonic signals. In one operating mode, it can be controlled as an actuator to generate the ultrasonic signals, while in a second mode, it functions as a sensor to receive the reflected ultrasonic signals. Thus, the ultrasonic sensor is both an actuator and a sensor in one. However, the ultrasonic sensor can also be configured for only one of these two operating modes.

[0029] With the aid of a control unit connected to the ultrasonic sensor, the sensor can be used in either the first or second operating mode. In the first mode, the control unit electrically drives the ultrasonic sensor, converting the electrical energy into ultrasonic signals. In the second mode, the reflected ultrasonic signals received by the sensor are converted back into electrical energy and can be evaluated by the control unit. This enables a pulse-echo method.

[0030] Typically, piezoelectric elements are used as ultrasonic sensors. These elements can convert electrical energy into motion and vice versa. By applying appropriate high-frequency signals, these piezoelectric elements can generate and receive ultrasonic signals.

[0031] According to the invention, at least one recess is provided in the forming tool surface, into which a forming tool insert is inserted in such a way that it forms part of this forming tool surface with one side, wherein the at least one ultrasonic sensor is acoustically connected to the forming tool insert and the forming tool insert is made of a material different from the metallic material of the forming tool surface.

[0032] Such a recess in the forming tool surface represents a depression into which a forming tool insert can be placed, thereby compensating for the depression in the forming tool surface, as if such a recess did not exist in the forming tool surface.

[0033] The recess in the forming tool surface can be continuous, allowing access from the underside of the forming tool towards the forming tool surface. In this embodiment, the forming tool insert can be inserted from both the forming tool surface and the underside of the forming tool. The cables required to control the ultrasonic sensor can then be easily routed out of the forming tool from the underside. Therefore, this embodiment is preferable.

[0034] The recess in the forming tool surface can also be designed as a blind hole, meaning the forming tool insert can only be inserted from the forming tool surface. The ultrasonic sensor can be connected wirelessly, for example, and may require wireless, external excitation or a self-contained power source.

[0035] The ultrasonic sensor required for ultrasonic monitoring is located on or within the mold insert and is connected or coupled to it. Specifically, the ultrasonic sensor is bonded to the mold insert, for example, by adhesive. However, it is also conceivable that the ultrasonic sensor is completely embedded in the mold insert and thus fully coupled to it.

[0036] The ultrasonic sensor can be, in particular, a piezoelectric element that is arranged on or in the mold insert or embedded within it. The piezoelectric element is connected to a control unit, either wired or wirelessly, so that the piezoelectric element can be controlled to generate ultrasonic signals.

[0037] Due to the fact that the ultrasonic sensor is embedded in a mold insert, and this mold insert differs from the metallic material of the molding tool surface and is not made of a metallic material, the impedance jump at the interface between the molding tool surface and the component formed on the molding tool surface can be reduced, thus reducing the proportion of reflected ultrasound and improving the measurement-noise ratio.

[0038] This makes it possible to use the appropriate pulse-echo method for ultrasonic monitoring, especially with open mold concepts, because the reduced impedance jump at the interface decreases the proportion of reflected sound, thus enabling the pulse-echo method to deliver a reliable monitoring result even with metallic molds.

[0039] According to one embodiment, the molding tool insert has an acoustic impedance that lies between the acoustic impedance of the molding tool surface and a fiber composite component produced and cured on the molding tool surface.

[0040] In this embodiment, the material of the mold insert is selected such that its acoustic impedance is approximated to that of the manufactured fiber composite component and thus moves away from the acoustic impedance of the molding tool surface. This reduces the impedance step. It is advantageous to consider the acoustic impedance of the fiber composite component in both its uncured or partially cured state and its fully cured state. This is because the acoustic impedance of the component varies between the uncured state of the matrix material and the fully cured state.

[0041] Accordingly, it is specifically intended that the material of the mold insert has an acoustic impedance that is smaller than the acoustic impedance of the material of the molding tool surface.

[0042] According to one embodiment, the acoustic impedance is provided to be more than 50% smaller, preferably more than 70% smaller.

[0043] According to one embodiment, the material of the mold insert has an acoustic impedance that differs from the impedance of a fiber composite component produced and cured on the molding tool surface or from an average acoustic impedance of the fiber composite component by no more than 20%, preferably by no more than 10%.

[0044] An average acoustic impedance can be determined, for example, by taking an average value between a first acoustic impedance in the uncured state and a second acoustic impedance in the cured state (e.g., the arithmetic mean).

[0045] According to one embodiment, the material of the mold insert has an acoustic impedance that lies between the acoustic impedance of a fiber composite component formed on the molding tool surface in the uncured state and the acoustic impedance of the fiber composite component in the cured state.

[0046] According to one embodiment, the mold insert is made of a thermoplastic material and / or a thermosetting material. Advantageously, the mold insert can be made of an epoxy resin.

[0047] According to the invention, one side of the mold insert forms part of the mold surface. Thus, while the mold surface is predominantly made of a metallic material, at the sensor positions where the ultrasonic sensors are located, the mold surface consists of a thermoplastic and / or thermoset material. This material has an acoustic impedance very close to that of the component being manufactured, so that the impedance jump in the area of ​​the mold insert between the mold insert (as part of the mold surface) and the component being manufactured is significantly reduced compared to the metallic mold surface.

[0048] It may be necessary to apply a release agent to the tool surface of the mold insert (i.e., the side that forms part of the forming tool surface of the entire mold) and / or the entire forming tool surface to ensure the manufactured fiber composite component can be separated from the mold surface, thus supporting or enabling the demolding process. The material of the mold insert(s) should therefore also meet the technical requirements for release and / or the chemical requirements for the use of release agents.

[0049] The problem is also solved according to the invention by the method according to claim 9 for producing a fiber composite component from a fiber composite material comprising a fiber material and a matrix material embedding the fiber material, wherein the method comprises the following steps: - Providing a forming tool according to one of the preceding claims, - Depositing fiber material onto the shaping tool surface, which is partly formed from the side of the at least one mold tool insert, and - Curing of the matrix material infused into the fiber material to produce the fiber composite component, - wherein ultrasound signals are emitted and / or received by means of the ultrasound sensor by means of the monitoring device for monitoring the infusion of the matrix material into the fiber material and / or for monitoring the curing of the matrix material.

[0050] According to one embodiment, a plurality of mold inserts made of different materials are provided, and the mold insert whose acoustic impedance is closest to that of the cured fiber composite component is selected. The materials provided must meet the thermal and mechanical requirements arising from the process.

[0051] In this process, the mold insert is selected whose material has an acoustic impedance that is closest to the acoustic impedance of the cured fiber composite component or an average value thereof, or lies between the acoustic impedance in the uncured state and the acoustic impedance in the cured state.

[0052] According to one embodiment, it is provided that at least one molding tool insert is placed in the molding tool before the fiber material is laid down onto the shaping tool surface.

[0053] According to one embodiment, a pulse-echo method is used for monitoring.

[0054] The invention is explained in more detail with reference to the accompanying figures. They show: Fig. 1 Schematic representation of a forming tool with a forming tool insert according to the invention; Fig. 2 Detailed view of a mold insert; Fig. 3. Schematic representation of different designs for attaching a mold insert.

[0055] Fig. Figure 1 shows a highly simplified schematic representation of a mold 10 with a forming tool surface 12. A fiber material 14 was deposited onto this forming tool surface 12 to produce a fiber composite component. After the fiber material 14 has been completely deposited, a cover plate 16 is placed on the opposite side of the mold 10, and the fiber material is then sealed vacuum-tight against the forming tool surface by creating a vacuum 18. The vacuum-tight fiber material 14 can then be evacuated and, if necessary, infused with matrix material. Finally, the matrix material is cured.

[0056] To monitor an infusion process and / or the hardening of the matrix material, the fiber material is irradiated with ultrasound signals. For this purpose, an ultrasound signal is generated using an ultrasound sensor and coupled into the fiber material 14, and the reflected ultrasound signal is then received again by the ultrasound sensor.

[0057] According to the invention, a mold insert 20 is used, which is inserted into the mold 10, more precisely into the molding tool surface 12, and contains the ultrasonic sensor (see Fig. 2) The mold insert 20 is flush with the forming tool surface 12 and forms part of the forming tool surface with one side 22, onto which the corresponding fiber material is deposited. Thus, after the fiber material has been deposited, the mold insert is in contact with it.

[0058] Fig. Figure 2 shows such a mold insert 20 in detail. The mold insert 20 has a base body 24, which can be made of a polymer, for example. This could be an epoxy resin, another thermosetting plastic, or a thermoplastic.

[0059] The base body 24 contains a sound absorber 26 made of foam, which carries the ultrasonic sensor 28. This ultrasonic sensor 28 is arranged on the sound absorber 26 such that the ultrasonic sensor 28 is oriented towards the tool surface 22 of the mold insert 20.

[0060] The electrical lines 30 required for contacting the ultrasonic sensor 28 are led out from the opposite side and can be connected to a corresponding control unit.

[0061] Such a mold insert 20 can be detachably inserted into the mold, with the mold surface 22 of the mold insert 20 being designed for depositing fiber material. Since the base body 24 consists of a material whose acoustic impedance is very similar to that of the component to be manufactured, the proportion of the ultrasonic signal reflected at the interface is significantly reduced due to the considerably lowered impedance step at the interface between the mold surface 22 of the mold insert 20 and the component placed on it. Thus, a pulse-echo method can be reliably carried out even with metallic molds.

[0062] Fig.Figure 3 shows two embodiments for attaching such a mold insert 20 to the mold. In the first embodiment a), the mold insert 20 is attached to the underside of the mold (not shown) by means of laterally projecting screws 32. The mold insert 20 has a thickness that corresponds to the thickness of the mold, so that the upper surface of the mold insert is flush with the rest of the mold.

[0063] In the second embodiment b), the molding tool insert is held by means of a clamp 34 so that fiber material can also be deposited on the inserted molding tool insert 20 and pressure can be built up if necessary. Reference symbol list 10 forming tools 12 shaping tool surfaces 14 Fiber material 16 Cover plate 18 Vacuum setup 20 Forming tool insert 22 Tool surface of the mold insert 24 basic shapes 26 sound absorbers 28 Ultrasonic sensor 30 Electrical contacting of the ultrasonic sensor 32 screws 34 bracket QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2010 015 027 B1

[0007] DE 197 37 276 C2

[0015] DE 10 2010 037 849 A1

[0016] EP 2 657 801 A2

[0017] DE 10 2016 112 263 A1

[0018]

Claims

[1] Molding tool (10) for producing a fiber composite component from a fiber composite material comprising a fiber material (14) and a matrix material embedding the fiber material (14) with at least one forming tool surface (12) made of a metallic material and with a monitoring device having at least one ultrasonic sensor (28) acoustically connected to the molding tool (10), wherein the ultrasonic sensor (28) is configured to emit ultrasonic signals into the component produced on the forming tool surface (12) and / or to receive the ultrasonic signals reflected from the component, characterized by, that at least one recess is provided in the at least one shaping tool surface (12) in which a forming tool insert (20) is inserted such that it forms part of this shaping tool surface (12) with one side, wherein the at least one ultrasonic sensor (28) is acoustically connected to the forming tool insert (20) and the forming tool insert (20) is made of a material different from the metallic material of the shaping tool surface (12). [2] Forming tool (10) according to claim 1, characterized by , that the molding tool insert (20) has an acoustic impedance that lies between the acoustic impedance of the molding tool surface (12) and a fiber composite component produced and cured on the molding tool surface (12). [3] Forming tool (10) according to claim 1 or 2, characterized by, that the material of the mold insert (20) has an acoustic impedance that is smaller than the acoustic impedance of the material of the molding tool surface (12). [4] Forming tool (10) according to claim 3, characterized by that the acoustic impedance is smaller by more than 50%, preferably by more than 70%. [5] Forming tool (10) according to any one of the preceding claims, characterized by , that the material of the mold insert (20) has an acoustic impedance that differs from the acoustic impedance of a fiber composite component produced and cured on the molding tool surface (12) or from an average acoustic impedance of the fiber composite component by no more than 20%, preferably by no more than 10%. [6] Forming tool (10) according to any one of the preceding claims, characterized by, that the material of the mold insert (20) has an acoustic impedance which lies between the acoustic impedance of a fiber composite component formed on the molding tool surface (12) in the uncured state and the acoustic impedance of the fiber composite component in the cured state. [7] Forming tool (10) according to any one of the preceding claims, characterized by , that the mold insert (20) is made of a thermoplastic material and / or a thermosetting material. [8] Forming tool (10) according to claim 7, characterized by , that the mold insert (20) is made of an epoxy resin. [9] Method for producing a fiber composite component from a fiber composite material comprising a fiber material (14) and a matrix material embedding the fiber material (14), the method comprising the following steps: - Providing a forming tool (10) according to one of the preceding claims, - Depositing fiber material (14) onto the forming tool surface (12), which is partly formed from the side of the at least one forming tool insert (20), and - Curing of the matrix material infused into the fiber material (14) to produce the fiber composite component, - wherein ultrasound signals are emitted and / or received by means of the ultrasound sensor (28) by means of the monitoring device for monitoring the infusion of the matrix material into the fiber material (14) and / or for monitoring the curing of the matrix material. [10] Method according to claim 9, characterized by, that a plurality of mold tool inserts made of different materials are provided, wherein the mold tool insert (20) is selected whose acoustic impedance is closest to the acoustic impedance of the cured fiber composite component. [11] Method according to claim 9 or 10, characterized by , that before the fiber material (14) is laid down onto the shaping tool surface (12) the at least one forming tool insert (20) is inserted into the forming tool (10). [12] Method according to any one of claims 9 to 11, characterized by that a pulse-echo method is used for monitoring.

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