Method for determining component thickness

Abstract

Method for determining a component thickness profile during the manufacture of a fiber composite component (200) made of a fiber composite material comprising a fiber material (210) and a matrix material (220) embedding the fiber material (210), wherein the method comprises the following steps: - providing a measuring device having at least one distance sensor (14) arranged on a motion device (20) for moving the distance sensor (14);- Determining a reference distance profile during a reference measurement using the measuring device, by moving the at least one distance sensor (14) along a tool (100) for the production of the fiber composite component (200) by means of the motion device (20) on at least one predetermined motion trajectory before the fiber material (210) for the production of the fiber composite component (200) is introduced into the tool (100), - wherein, in order to determine the reference distance profile, a plurality of reference distances (dref) between the at least one distance sensor (14) and a tool surface (130) of the tool (100) are determined when moving the distance sensor (14) along the at least one motion trajectory;and after the fiber material (210) has been introduced into the tool (100) to form the fiber composite component (200): - Determining at least one component distance profile during a component measurement using the measuring device, by moving the at least one distance sensor (14) along the tool (100) by means of the movement device (20) on at least one predetermined movement trajectory, - wherein, in order to determine the component distance profile, a plurality of component distances (dbau) between the at least one distance sensor (14) and a component surface (230) of the fiber composite component (200) formed in the tool (100) are determined when moving the distance sensor (14) along the at least one movement trajectory;and- Calculating a component thickness profile of the fiber composite component (200) formed in the tool (100) as a function of the determined reference distance profile and the at least one component distance profile using an evaluation unit (22).;

Description

The invention relates to a method for determining a component thickness profile during the production of a fiber composite component made of a fiber composite material comprising a fiber material and a matrix material embedding the fiber material. The invention also relates to a method for manufacturing such a fiber composite component. Due to their particularly advantageous property of exhibiting high strength-to-weight ratio and stiffness at a very low weight, fiber-reinforced composite components made from fiber-reinforced composite materials are now used in many fields of application. Such materials are virtually indispensable, especially in the aerospace and automotive sectors, as they offer optimal adaptations, particularly with regard to lightweight construction. Nowadays, structurally critical components are often manufactured and used from fiber-reinforced composites, such as aerodynamic bodies (wings) or fuselage shells of aircraft. Fiber-reinforced composite components are also increasingly used in the automotive sector, as the resulting weight savings usually translate into proportionally lower fuel consumption. The aim is to enable the reliable and consistent production of fiber-reinforced composite components in series production. A key criterion here is to design the manufacturing process with process and quality reliability, and in particular to be able to monitor each individual production step seamlessly and reliably. Only in this way can it be ensured that defective components are detected reliably and efficiently as early as possible during the manufacturing process. The earlier a defective component is identified in the entire manufacturing process, the fewer resources are unnecessarily spent on its completion. This ultimately reduces the cost per component and thus promotes acceptance in industrial applications. A widely used manufacturing process is the curing of a fiber-reinforced composite component in an autoclave. Under pressure (up to 10 bar) and temperature (more than 200°C, sometimes even 400°C), the component, consisting of fiber material and matrix system, is cured so that the fibers form an integral bond with the matrix material. This integral bond forces the fibers into their predetermined orientation, enabling them to optimally bear the loads. Since the autoclave process represents a crucial step in the overall manufacturing process, close attention is paid to monitoring the individual parameters of this step. An important parameter here is determining the component thickness during the curing process, as this allows conclusions to be drawn about the quality of the manufacturing process. The compaction of the fiber material impregnated with the matrix material during the curing process is usually achieved through the use of differential pressure. For this purpose, a vacuum is created, often using a plastic film that seals the component against ambient pressure at its edges. The shape and the film thus form a hermetically sealed cavity in which the fiber material is enclosed. Evacuating the cavity creates a differential pressure, which compacts the composite of fiber and matrix material during curing. An autoclave can be used to increase this differential pressure.Creating such a vacuum setup is very time-consuming, technically very demanding, and of great interest for the manufacturing of the component. It is known to determine component thickness using ultrasound. For this purpose, an ultrasound signal is coupled into the component and the transit time of the ultrasound signal through the component is measured. However, integrating ultrasonic sensors into the vacuum setup has its drawbacks. The plastic film must be opened, creating potential leak points that should generally be avoided, as this could lead to the component being rejected. Furthermore, this type of integration makes the vacuum setup even more time-consuming and complex. Another disadvantage is that this type of thickness measurement yields insufficient results, as the speed of sound is a variable dependent on the curing or consolidation state. This is because the matrix material changes its physically determined parameter of sound velocity during the curing process. This ultimately leads to inaccurate calculations. Consequently, complex calibration procedures tailored to the specific composition of the matrix material are required. From DE 10 2013 108 568 A1, a method and a device for determining component thickness are known, in which the distance between the sensor and the mold or the component surface is determined using a stationary laser distance sensor. Subsequently, the actual component thickness is determined locally at a specific position by calculating the difference between the distance between the sensor and the mold, and between the sensor and the component surface. A disadvantage of this method, however, is that it can only indicate the component thickness at discrete positions and within a limited local area. This can potentially lead to defects, which would be detectable as deviations from the expected component thickness, going undetected if the defects are not located precisely at the stationary measurement position. German patent DE 10 2005 009 262 A1 discloses a method for measuring the layer thickness of a coating applied to a surface, for example, a paint. During the coating process, the distance between a first sensor and the surface of the coating, as well as between a second sensor and the substrate surface, is determined. The sensors can be optical. The thickness of the coating can then be derived from the two distances thus determined between the first and second sensors. DE 10 2013 107 214 A1 discloses the ability to monitor the position of additional components on a large component during the curing of the matrix material in order to detect any slippage or sliding of the additional component during pressure and temperature exposure. It is therefore an object of the present invention to provide an improved method and an improved device with which the component thickness can be fully recorded during the manufacturing process of a fiber composite component, in order to be able to detect defects early in the manufacturing process. The problem is solved according to the invention by the method for determining a component thickness profile according to claim 1. The problem is also solved according to the invention by the method for manufacturing a fiber composite component according to claim 7. Advantageous embodiments of the invention are found in the corresponding dependent claims. According to claim 1, a method for determining a component thickness profile during the manufacture of a fiber composite component made of a fiber composite material comprising a fiber material and a matrix material embedding the fiber material is proposed, wherein a reference measurement without a component and subsequently a component measurement with a component are carried out using a provided measuring device, wherein a component thickness profile can then be determined over the entire component based on the measurement results of the reference measurement and the component measurement. A component thickness profile, as defined in the present invention, is a data set containing a multitude of values ​​relating to the thickness (extent of the component in the Z-direction) of the component. Knowing the surface area of ​​the component (extent of the component in the XY-direction), a type of three-dimensional component model can be generated. The component thickness profile contains thickness information not only along a line on the component, but preferably distributed across the entire surface of the component. A measurement data point of such a component thickness profile has a spatial reference relative to the component at which the component thickness was determined, such that the measurement data point corresponds to the component thickness at this spatial reference point.The spatial references of the measurement data preferably vary with respect to both the X-dimension and the Y-dimension, resulting in a planar measurement field across the entire two-dimensional surface of the component. According to the invention, a measuring device is first provided which has at least one distance sensor arranged on a movement device for moving the distance sensor. Such a distance sensor can determine the distance between a reference point of the distance sensor and a surface that is subject to a complaint, in particular a component surface of a fiber composite component. Such a distance sensor can, for example, be a laser distance sensor. Using the motion device, at least one distance sensor can be moved relative to the component, so that the distance can be determined using the distance sensor at different positions in relation to the component. A reference measurement is first performed using the measuring device to determine a reference distance profile. In this process, the at least one distance sensor is moved along a tool for manufacturing the fiber composite component by means of the motion device along at least one predetermined motion trajectory, whereby a plurality of reference distances between the at least one distance sensor and a tool surface of the tool are determined as the distance sensor moves along the motion trajectory. After the fiber material is introduced into the tool to form the component, at least one component measurement is performed to determine the component distance profile. In this process, the at least one distance sensor is moved along the tool by means of the motion device along at least one predefined motion trajectory. During this movement of the distance sensor along the at least one predefined motion trajectory, a multitude of component distances between the at least one distance sensor and a component surface of the component formed in the tool are determined. Both the reference distance profile and the at least one component distance profile, previously determined by the measuring device, are stored in a digital data memory for later access. During both the reference measurement and the component measurement, the distance sensor is continuously moved along the at least one motion trajectory by means of the motion device, with the distance being determined during the movement of the distance sensor. In particular, the distance sensor is not intended to stop its movement for each distance measurement. Using an evaluation unit, a component thickness profile can now be determined based on the stored reference distance profile and the stored component distance profile, which represents the difference between reference distance and component distance in relation to the distance sensor. The present invention thus makes it possible to determine the component thickness as a thickness profile after any number of relevant manufacturing steps, thereby gaining knowledge about the development of the component thickness throughout the entire manufacturing process and, if necessary, permanently storing this information for later component documentation. Furthermore, the thickness profile allows for the identification of defects and process deviations at a very early stage. Compared to the prior art, the present method has the advantage that the component thickness is not only determined at discrete, isolated measuring positions, but can be determined across the entire component. This eliminates detection gaps, which are prevalent in the prior art. It is conceivable and also advantageous if different movement trajectories are followed in both the reference measurement and the component measurement in order to capture the entire component if possible. The inventors recognized that, despite the poor reflective properties of the surfaces of a fiber composite component, the distance can still be reliably determined using a distance sensor if the distance sensor is continuously moved along a motion trajectory by means of a motion device and the distance to the component surface is determined during the movement. The measuring device can be designed such that the distance sensor is mounted on a frame by means of the motion device, with the frame being stationary relative to the mold. This ensures that the motion trajectory of the reference measurement and the motion trajectory of the component measurement are identical. In other words, the motion trajectory along which the distance sensor is moved relative to the mold or the component by means of the motion device is identical (within tolerances) for each measurement, so that no correction of the measurement data is necessary. The measuring device can also be designed such that the distance sensor is mounted on a robot, particularly an industrial robot or articulated robot, as a motion device, so that different and distinct motion trajectories are followed for each measurement. In this case, it becomes necessary to also record the position of the distance sensor relative to the tool (or another reference coordinate system) for each measured distance, so that the distances of the reference measurement and the distances of the component measurement can be normalized to a common motion trajectory based on the positions of the distance sensor during the respective measurement. According to one embodiment, the component thickness profile is calculated by the evaluation unit by determining the distance differences between the reference distances of the reference distance profile and the corresponding component distances of the component distance profile. The difference is preferably calculated between a reference distance and a component distance whose measurement positions are of a predetermined proximity to the component or tool. The measurement position of a distance measurement can be stored along with the measurement data when the distance sensor is moved. Such a measurement position can also be implemented using a temporal aspect. According to one embodiment, the measuring device is configured such that the at least one distance sensor is a laser distance sensor, with the reference distances and component distances being determined by means of a laser beam emitted by the laser distance sensor. The laser distance sensor emits a laser beam that is reflected from the surface of the tool or component and can be detected by the laser distance sensor. Based on a time-of-flight or phase measurement, the distance can then be determined accordingly. According to one embodiment, the measuring device is provided such that the at least one distance sensor is a line laser distance sensor, wherein the reference distances and the component distances are determined by means of a laser line emitted by the line laser distance sensor. A line laser distance sensor emits a laser line on which a multitude of measuring positions lie. Using such a line laser distance sensor, a multitude of distances can be determined at a specific measuring position, all of which lie on the laser line projected onto the respective surface. If such a line laser distance sensor is now moved along the predetermined trajectory using the motion device, many distances can be determined at each specific measuring position, thereby generating an area-wide measuring field in a single measurement pass. In this context, it is particularly advantageous if the laser line of the laser line distance sensor is emitted perpendicular to the direction of motion, whereby a plurality of reference distances and component distances are determined along the laser line as the laser line distance sensor is moved. Preferably, the laser line is emitted orthogonally to the direction of motion of the laser line distance sensor in order to generate the widest possible measurement field. According to one embodiment, the component thickness profile is further determined by the evaluation unit as a function of a known thickness (film thickness) of a vacuum setup and / or a known peel fabric thickness. The problem is also solved by a process for manufacturing a fiber-reinforced composite component from a fiber-reinforced composite material comprising a fiber material and a matrix material embedding the fiber material, wherein the fiber material of the fiber-reinforced composite is introduced into a mold to form the component, and the matrix material embedding the fiber material is consolidated. The introduction of the fiber material can be automated by a fiber laying system. However, it is also conceivable that the fiber material is introduced into the mold manually. According to the invention, it is now provided that during the production of the fiber composite component, at least one component thickness profile of the component formed in the mold is determined using the method as described above. According to one embodiment, during the production of the fiber composite component, at least one parameter of the manufacturing process is automatically adjusted, changed, and / or set by the evaluation unit, depending on the determined component thickness profile. Such a parameter could, for example, be the pressure and / or temperature in an autoclave. Another example of such a parameter could be the vacuum generated under a vacuum setup during the evacuation of the component. The problem is also solved by the device for determining a component thickness profile during the production of a fiber composite component made of a fiber composite material comprising a fiber material and a matrix material embedding the fiber material, wherein the device has a measuring device which has at least one distance sensor which is arranged on a movement device for moving the distance sensor and is configured to determine a distance, and an evaluation unit for determining the component thickness profile, wherein the device for carrying out the method is set up and designed as described above. The device could, for example, be a fiber laying system of the type used to automatically deposit fiber material onto a tool. The invention is explained in more detail by way of example with reference to the accompanying figures. These show: Fig. 1 a schematic representation of the device-related operating principle; Fig. 2 a schematic representation of the process sequence; Fig. 3 a representation of a recorded component thickness profile. Fig. 1 shows a highly simplified schematic representation of a device 10 designed for determining the thickness profile of a fiber-reinforced composite component during its production. A fiber-reinforced composite component 200 is produced on a mold 100. To produce the fiber-reinforced composite component, fiber material 210 of the fiber-reinforced composite material is introduced into the mold 100, after which the matrix material 220 embedding the fiber material 210 is consolidated or cured. The device 10 has a mounting 12 on which a distance sensor 14 is arranged. The distance sensor 14 is designed as a laser line distance sensor and emits a laser beam 16 which is visible on the projected surface as a laser line 18. The laser line distance sensor is set up on this laser line 18 to determine the distance between the projected surface and the distance sensor 14 at a large number of measuring points. This allows a large number of distances between the distance sensor 14 and the projected surface to be determined at a specific component position using the laser line distance sensor. The distance sensor 14 is arranged on a motion device 20, which is configured to move the distance sensor 14 along a motion trajectory relative to the mold 100 or the fiber composite component 2. In the illustration of Fig. 1, the movement of the distance sensor 14 by means of the motion device 20 takes place out of the plane of view, since Fig. 1 shows a cross-sectional view of the direction of movement. The distance sensor 14 is configured to determine a distance to the component surface 230 or the tool surface 130 of the mold 100. In a reference measurement, the distance (reference distance) between the distance sensor 14 and the tool surface 130 is determined, while in a component measurement, the distance (component distance) between the distance sensor 14 and the component surface 230 of the fiber composite component 200 is determined. By calculating the difference between the reference distance and the component distance, the component thickness d at a specific measurement position can be determined. The measurement position refers to a two-dimensional position on the component surface. Fig. 2 schematically illustrates the process flow for determining the component thickness profile and / or manufacturing the component. In a first step a), a reference distance dref is determined between the distance sensor 14 and the tool surface 130. The entire tool surface 130 is measured, so that a corresponding reference distance dref is determined for each position of the tool surface 130. This reference measurement in the first step a) then yields a reference distance profile that contains a reference distance dref for the two-dimensional surface of the tool surface 130 at the respective measurement position. Each reference distance dref is identified by a two-dimensional position coordinator (x, y). In the next step b), the fiber material for forming the component 200 is introduced onto the tool surface 130. The fiber material can be introduced into the mold 100 dry or pre-impregnated. If the fiber material is introduced in a dry state, it can be infused with the matrix material in a subsequent step. In the last step c), the execution of a component measurement is shown schematically. As with the previous reference measurement, the distance sensor 14 determines a component distance dbau at a large number of measuring positions, which indicates the distance between the distance sensor 14 and the component surface 230. Using an evaluation unit 22 connected to the distance sensor 14, the component thickness profile can now be determined from the reference distance profile determined in the first step a) and the component distance profile determined in the third step c). This yields the corresponding component thickness at each measurement position. Fig. 3 shows such a component thickness profile, which depicts the thickness of the component at various positions across the entire surface of the component. Reference symbol list 10 Device 12 Frame 14 Distance sensor 16 Laser beam 18 Laser line 20 Motion device 22 Evaluation unit 100 Tool 130 Tool surface 200 Fiber composite component 210 Fiber material 220 Matrix material 230 Component surface drefReference distance dbauComponent distance

Claims

Method for determining a component thickness profile during the manufacture of a fiber composite component (200) made of a fiber composite material comprising a fiber material (210) and a matrix material (220) embedding the fiber material (210), wherein the method comprises the following steps: - providing a measuring device having at least one distance sensor (14) arranged on a motion device (20) for moving the distance sensor (14);- Determining a reference distance profile during a reference measurement using the measuring device, by moving the at least one distance sensor (14) along a tool (100) for the production of the fiber composite component (200) by means of the motion device (20) on at least one predetermined motion trajectory before the fiber material (210) for the production of the fiber composite component (200) is introduced into the tool (100), - wherein, in order to determine the reference distance profile, a plurality of reference distances (dref) between the at least one distance sensor (14) and a tool surface (130) of the tool (100) are determined when moving the distance sensor (14) along the at least one motion trajectory;and after the fiber material (210) has been introduced into the tool (100) to form the fiber composite component (200): - Determining at least one component distance profile during a component measurement using the measuring device, by moving the at least one distance sensor (14) along the tool (100) by means of the movement device (20) on at least one predetermined movement trajectory, - wherein, in order to determine the component distance profile, a plurality of component distances (dbau) between the at least one distance sensor (14) and a component surface (230) of the fiber composite component (200) formed in the tool (100) are determined when moving the distance sensor (14) along the at least one movement trajectory;and- Calculating a component thickness profile of the fiber composite component (200) formed in the tool (100) as a function of the determined reference distance profile and the at least one component distance profile using an evaluation unit (22).; Method according to claim 1, characterized in that the component thickness profile is calculated using the evaluation unit (22) by determining distance differences between the reference distances (dref) of the reference distance profile and the corresponding component distances (dbau) of the component distance profile. Method according to claim 1 or 2, characterized in that the measuring device is provided such that the at least one distance sensor (14) is a laser distance sensor, wherein the reference distances (dref) and the component distances (dbau) are determined by means of a laser beam (16) emitted by the laser distance sensor. Method according to one of the preceding claims, characterized in that the measuring device is provided such that the at least one distance sensor (14) is a line laser distance sensor, wherein the reference distances (dref) and the component distances (dbau) are determined by means of a laser line (18) emitted by the line laser distance sensor. Method according to claim 4, characterized in that the laser line (18) is emitted transversely to the movement trajectory, wherein a plurality of reference distances (dref) and component distances (dbau) are determined along the laser line (18) when moving the line laser distance sensor. Method according to one of the preceding claims, characterized in that the component thickness profile is further determined by the evaluation unit (22) as a function of a known thickness of a vacuum setup and / or a known peel fabric thickness. Method for producing a fiber composite component (200) from a fiber composite material comprising a fiber material (210) and a matrix material (220) embedding the fiber material (210), wherein the fiber material (210) of the fiber composite material is introduced into a tool (100) to form the fiber composite component (200) and the matrix material (220) embedding the fiber material (210) is consolidated, characterized in that during the production of the fiber composite component (200) at least one component thickness profile of the fiber composite component (200) formed in the tool (100) is determined using the method according to one of claims 1 to 6. Method according to claim 7, characterized in that during the production of the fiber composite component (200), at least one parameter of a manufacturing process for the production of the fiber composite component (200) is automatically adjusted, changed and / or set by the evaluation unit (22) depending on the determined component thickness profile.

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