Method and system for surface inspection of cured composite parts including glass fibers and carbon fibers

Abstract

The invention relates to a method and a system for surface inspection of a cured composite part comprising glass fibers and carbon fibers. The cured composite part is in particular a cured composite part of an aircraft, the method comprising the steps of illuminating the surface of the composite part to be inspected with infrared light emitted from an IR light source and capturing an image of the surface. The IR light source is arranged such that the generated infrared light hits the surface at a first angle a to provide dark field illumination of the surface and the camera is arranged such that it is directed at the surface under inspection at a second angle β to capture an image of the dark field illuminated surface. The captured image is evaluated with respect to brightness and contrast to detect one or more glass fiber layers on top of one or more carbon fiber layers within the composite part.

Description

Technical Field

[0001] This invention relates to a method for surface inspection of cured composite parts comprising glass fiber and carbon fiber. Furthermore, this invention relates to a system for surface inspection of cured composite parts comprising glass fiber and carbon fiber. Additionally, this invention relates to the use of an infrared (IR) light source and camera in the method for surface inspection of cured composite parts. This method and system are particularly suitable for inspecting composite parts of aircraft. Background Technology

[0002] Many composite components in aircraft include carbon fiber layers and glass fiber layers; that is, such components include CFRP (carbon fiber reinforced polymer) and GFRP (glass fiber reinforced polymer). For example, one or more glass fiber layers may cover the carbon fiber layer. The glass fiber layer is specifically used to avoid direct contact between the carbon fiber and aluminum when the composite component is attached to another component made of aluminum, which would lead to corrosion.

[0003] However, what may occur in cured composite parts is that the fiberglass layer is missing, or that the fiberglass layer is located where it should not be. Furthermore, for example, two fiberglass layers may be located where only one fiberglass layer should be present. These are examples of defects in cured composite parts that need to be inspected.

[0004] According to existing technology, the presence of glass fibers can be detected using active thermal imaging, which employs a calorimeter with an additional excitation source, such as a halogen lamp or a high-power LED flash. However, this requires a relatively long data acquisition time. Furthermore, it typically raises the temperature of the object being inspected by several degrees. This is not optimal for use cases where a relatively short acquisition time is required and minimal impact on high-value objects, such as aircraft flaps or other aircraft components, is desired. Summary of the Invention

[0005] The purpose of this invention is to provide a method and system for surface inspection of cured composite parts comprising glass fiber and carbon fiber, which can detect defects related to the location and number of glass fiber layers with high accuracy and faster speed while minimizing the impact on the cured composite parts.

[0006] This objective is achieved by a method for surface inspection of cured composite parts comprising glass fiber and carbon fiber, particularly cured composite parts for aircraft, the method comprising the steps of: illuminating the surface of the composite part to be inspected with infrared light emitted from an IR light source and capturing an image of the surface with a camera, wherein the IR light source is arranged such that the infrared light hits the surface at a first angle to provide dark field illumination of the surface, and wherein the camera is arranged such that the camera is pointed at the surface to be inspected at a second angle to capture an image of the dark field illuminated surface; and detecting one or more glass fiber layers on top of one or more carbon fiber layers within the composite part by evaluating the captured image with respect to brightness and contrast.

[0007] This invention results in strong contrast between the GFRP and CFRP layers and a short inspection time. Specifically, only one exposure is required at a single location. Furthermore, there is no need to wait for the excitation source to phase.

[0008] Preferably, the IR light source and camera are arranged relative to the surface being inspected such that the infrared light and the camera are pointing at the surface from the same direction.

[0009] For example, the first angle at which infrared light hits the surface is between 20 and 50 degrees.

[0010] Preferably, the first angle at which the infrared light strikes the surface is between 25 and 35 degrees.

[0011] Most preferably, the first angle at which the infrared light strikes the surface is approximately 30 degrees.

[0012] For example, the second angle at which the camera points to the surface is between 30 and 60 degrees.

[0013] Preferably, the second angle at which the camera points to the surface is between 40 and 50 degrees.

[0014] Most preferably, the second angle at which the camera points to the surface is approximately 45 degrees.

[0015] Preferably, the infrared light hits the surface from the same direction that the camera is pointing at the surface.

[0016] Preferably, the first angle is different from the second angle.

[0017] Specifically, the first angle is smaller than the second angle.

[0018] Preferably, the infrared light emitted by the IR light source forms a beam that is emitted along the beam direction and includes a spatial component that extends perpendicular to the beam direction and parallel to the surface being inspected.

[0019] Preferably, the camera has a field of view and / or a line scan direction that extends parallel to the spatial component of the light beam.

[0020] Preferably, infrared light is located at the boundary of visible light.

[0021] Preferably, the infrared light has a wavelength of about 850 nm.

[0022] Preferably, the camera is a monochrome camera.

[0023] Preferably, the camera is an infrared camera.

[0024] Preferably, the camera is a CMOS camera.

[0025] Preferably, the camera is a line scan camera.

[0026] Preferably, the camera includes a band filter that allows a wavelength band of about 850 nm to pass through.

[0027] The camera may also be without a filter.

[0028] Therefore, even higher scanning speeds can be achieved for scanning the surface being inspected.

[0029] However, the camera can also be constructed as a matrix camera. This can lead to specific advantages depending on the application.

[0030] Preferably, the IR light source and camera are positioned above the top edge of the part during inspection, and mirrors are positioned on one or both sides of the part such that the mirrors deflect the infrared light onto the surface at a first angle α, and the camera is pointed at the mirrors so as to point at the surface at a second angle β.

[0031] According to another aspect of the invention, a system is provided for surface inspection of cured composite parts comprising glass fiber and carbon fiber, particularly cured composite parts for aircraft, the system comprising an IR light source and a camera, both configured to perform the method according to the invention.

[0032] According to another aspect of the invention, an IR light source and a camera are provided for use in the method according to the invention.

[0033] The strong contrast is due to the fact that GFRP has relatively high reflectivity under dark-field IR light conditions according to the present invention.

[0034] Furthermore, due to the uniform distribution of light, there is no overexposure or underexposure in the image. The system can be positioned relatively close to the surface of a part or object, so that external light sources will not have a significant impact on data quality.

[0035] Furthermore, a large and scalable field of view with high spatial resolution is achieved. For example, the system can cover 100 mm to 500 mm. In addition, this invention results in low power consumption, safe operation for the operator, and a compact system that is easy to integrate. Attached Figure Description

[0036] In the following description, embodiments of the invention are described in more detail with reference to the accompanying drawings, in which:

[0037] Figure 1 A schematic side view of the system is depicted when performing the method according to a first embodiment of the present invention;

[0038] Figure 2 A schematic side view of the system is depicted when performing the method according to the second embodiment of the present invention; and

[0039] Figure 3 Describes the process when executing this method. Figure 2 The diagram shows a schematic front view of the system. Detailed Implementation

[0040] Reference Figure 1 The present invention describes a method according to a preferred embodiment of the present invention and a preferred system 10 used in the method.

[0041] System 10 is designed for surface inspection of a cured composite part 12 of an aircraft. System 10 includes an infrared or IR light source 14 that emits infrared (IR) light 16 to illuminate the surface 18 of the composite part 12. The composite part 12 includes glass fibers 22, which are arranged, for example, as one or more glass fiber layers 24 within the composite part 12. Additionally, the composite part 12 includes carbon fibers 26, which are arranged, for example, as one or more carbon fiber layers 28. In this example, a glass fiber layer 24 is positioned above a carbon fiber layer 26 in region A of the composite part 12, while only glass fiber layers 26 exist in other regions.

[0042] In other examples, the composite parts are made solely of carbon fiber. In this case, system 10 is used to locate glass or glass fiber, or other foreign objects that should not be present. The system can also be used to inspect composite parts made entirely of glass fiber.

[0043] An infrared or IR light source 14 is arranged above the surface 18 being inspected such that the generated infrared light 16 strikes the surface 18 at a first angle α to provide dark field illumination of the surface 18.

[0044] The camera 32, preferably a high-resolution monochrome camera, is also positioned above the surface 18 such that its observation direction or optical axis 33 points to the surface 18 at a second angle β, so as to capture an image of the surface 18 when the surface 18 is illuminated by infrared light 16.

[0045] The infrared light source 14 and camera 32 are arranged on the same side of the surface 18 being inspected. This means that the infrared light source 14 and camera 32 are arranged relative to the surface 18 being inspected such that the infrared light 16 and camera 32 are emitted from the same direction, i.e., in... Figure 1 The beam is directed from the right side toward surface 18. In this way, infrared light 16, forming a beam with beam direction B, is directed from camera 32 at an angle β to the same direction as the irradiated surface 18, irradiating surface 18 at an angle α.

[0046] During the inspection of the cured composite part 12, an infrared light source 14 and a high-resolution camera 32 are positioned relative to the surface 18 to be inspected as described above, wherein, as described above, the infrared light source 14 illuminates the surface 18 using dark field illumination and the camera 32 captures an image of the dark field illuminated surface 18.

[0047] Preferably, the infrared light source 14 and the camera 32 move together relative to the surface 18 to scan the surface 18. The infrared light source 14 and the camera 32 together can form an end effector unit configured for mounting to a robotic arm for moving and scanning the surface 18.

[0048] An evaluation of brightness and / or contrast is performed on the image captured by camera 32. In this way, one or more glass fiber layers 24 located on one or more carbon fiber layers 26 are detected.

[0049] The captured images are evaluated for different brightness and / or contrast in image regions or pixels to detect glass fibers within the composite part 12. Preferably, the image data generated by the camera 32 is automatically evaluated by an evaluation system not shown in the figures.

[0050] The method and system 10 described herein utilize the difference in light absorption and reflection between glass fiber 22 and carbon fiber 26. This difference is emphasized by both the infrared light 16 and the angle α at which the infrared light 16 strikes or shines on surface 18. Glass fiber 22 or glass fiber layer 24 absorbs less infrared light than carbon fiber 26 or carbon fiber layer 28.

[0051] Camera 32 is preferably a CMOS camera. The CMOS (Complementary Metal-Oxide-Semiconductor) sensor of camera 32, configured as a CMOS camera, has relatively high quantum efficiency in the NIR range. Furthermore, it is relatively inexpensive and easy to integrate. Taking all factors into account, a wavelength of 850 nm is most preferably selected for the IR light source, and a monochrome CMOS camera is most preferably used.

[0052] Most preferably, camera 32 is configured as a line scan camera. This allows for even higher surface inspection speeds. However, a matrix camera can also be used.

[0053] In particular, the method and system 10 utilize the fact that glass fiber 22 reflects more diffuse infrared light 16 than carbon fiber 26. This difference allows for a contrast between near-infrared (NIR) and short-wave infrared (SWIR) images.

[0054] The tilt angle α at which the IR beam 16 strikes surface 18 is preferably about 30°. However, the tilt angle α can also deviate from this ideal value and fall within the range of 25° to 35° or 20° to 50°. The tilt angle β at which the camera 32 aims at surface 18 is preferably about 45°. However, the tilt angle β can also deviate from this value and fall within the range of 40° to 50° or 30° to 60°. Angle β is typically larger than angle α to achieve good results.

[0055] An infrared light 16, formed by an IR light source 14 and emitted in a beam direction B, can extend in a direction B perpendicular to the beam 16 and parallel to the surface 18 being inspected. The camera 32 can have a field of view F or a line scan direction that extends parallel to the direction P of the beam 16.

[0056] The light 16 emitted by the IR light source 14 is, for example, at the edge of the visible light spectrum. For optimal results, the wavelength of the IR light 16 is 850 nm.

[0057] The method described above, and by using system 10, achieves optimal contrast on the glass fiber 22 on top of the carbon fiber 26.

[0058] Specifically, it can be determined whether there is only one layer or two layers 24 of glass fiber provided on the carbon fiber layer 28. Furthermore, it can be detected whether a layer 24 of glass fiber 22 is absent on top of the carbon fiber 26 or the carbon fiber layer 28. Therefore, it can be detected whether the glass fiber layer 24 is missing or located in the wrong position within the cured composite part 12.

[0059] Because the IR light source 14 illuminates the surface 18 at an angle and the camera 32 observes the surface 18 from the same side at an angle to capture an image, the reflection of the carbon fiber 26 is avoided in the image captured by the camera 32, resulting in higher contrast between the glass fiber 22 and the carbon fiber 26.

[0060] Figure 2 and Figure 3 A second embodiment of the system and method as described above is shown. Figure 2 With Figure 1 A similar side view shows the system 10 during operation and the composite part 12 to be inspected. Figure 3The previous view shows the system 10 during operation and the composite part 12 to be inspected.

[0061] In this embodiment, a mirror arrangement structure including two mirrors 42, 44 is additionally provided in system 10. All other features and details of system 10 are the same as those described above. Figure 1 The same as in the first embodiment described.

[0062] Reference above Figure 1 Compared to the described method, in this example, the composite part 12 to be inspected is arranged vertically, i.e., the surface 18 to be inspected extends with a spatial component in the direction of the positions of the IR light source 14 and the camera 32. Both the IR light source 14 and the camera 32 are located above the top edge 54 of the composite part 12, wherein the surface 18 to be inspected of the composite part 12 is located on one or both sides 55 of the composite part 12.

[0063] In other words, the surface 18 to be inspected extends in a plane that is parallel to the observation direction or optical axis 33 of the camera 14 and parallel to the direction B of the IR beam 16 emitted from the IR light source 14.

[0064] To examine the composite component 12, IR light source 14, and IR camera 32 in this example, refer to the above. Figure 1 The arrangement is as described in the example; however, the surface 18 to be inspected is oriented vertically, that is, perpendicular to its orientation. Figure 1 The orientation shown is as shown.

[0065] The infrared light 16, which forms a beam and is emitted by the IR light source 14 along the beam direction B, extends with its spatial component in the direction P, which is perpendicular to the direction B of the emitted IR beam 16 and also perpendicular to the surface 18 being inspected.

[0066] The camera 32 has an observation direction or optical axis 33 extending in a spatial component parallel to the direction P extending the beam 16, and preferably a flat field of view F or, in the case of an online scanning camera, a line scanning direction.

[0067] A mirror 42 is arranged on one or preferably both sides 55 of the composite part 12, that is, on one or preferably both sides 55 of one or more surfaces 18 to be inspected, such that the IR light 16 emitted by the IR light source 14 is deflected by the mirror 42 to strike or illuminate the corresponding surface 18 at a first angle α to provide dark field illumination of the surface 18, and the observation direction 33 of the camera 32 is deflected by the mirror 42 and pointed to the surface 17 so as to point to the surface 18 at a second angle β.

[0068] The surface of each mirror 42 preferably extends with its spatial component S parallel to the surface 12 to be inspected. The IR light source 14 and the camera 32 are arranged such that they form angles α and β with respect to the spatial component S, respectively.

[0069] In the example shown here, a composite part 12 having one or two surfaces 18 is arranged on a base region 56 extending perpendicularly to the inspected surface 18 of the composite part 12. After being deflected by the mirror 42, the angle α at which the infrared light 16 hits or shines on the surface 18 and the angle β at which the camera 32 points to the surface 18 are equal to the corresponding angles of the observation direction 33 of the IR light 16 and the camera 32 with respect to the base surface 56.

[0070] All other details and features of the method shown in this example are the same as those referenced above. Figure 1 The description is the same.

[0071] List of reference numerals in the attached diagram:

[0072] 10 Surface Inspection System

[0073] 12 Composite parts

[0074] 14 Infrared light source

[0075] 16 Infrared light

[0076] 18 Surface

[0077] 22 Glass fiber

[0078] 24 glass fiber layers

[0079] 26 Carbon fiber

[0080] 28 carbon fiber layers

[0081] 32 cameras

[0082] 33. Camera's viewing direction or optical axis

[0083] 42 mirrors

[0084] 54 Top edge

[0085] 55 Side

[0086] 56. Base Area

[0087] Direction of BIR beam

[0088] F field of view

[0089] Extension direction of P IR beam

[0090] The spatial component of the S-mirror parallel to the surface to be inspected

[0091] α First Angle

[0092] β Second Angle

Claims

1. A method for surface inspection of a cured composite part comprising glass fiber (22) and carbon fiber (26), the cured composite part being particularly a cured composite part for an aircraft, the method comprising the following steps: The surface (18) of the composite part (12) to be inspected is illuminated by infrared light (16) emitted from infrared light source (14). And using a camera (32) to capture images of the surface (18), wherein The infrared light source (14) is arranged such that the infrared light (16) strikes the surface (18) at a first angle α to provide dark-field illumination of the surface (18). Furthermore, the camera (32) is arranged such that the camera (32) points at the surface (18) being inspected at a second angle β to capture an image of the surface (18) under dark field illumination; And by evaluating the brightness and contrast of the captured images, one or more glass fiber layers (22) on top of one or more carbon fiber layers (28) within the composite part (12) are detected.

2. The method of claim 1, wherein, The infrared light source (14) and the camera (32) are arranged relative to the surface (18) being inspected such that the infrared light (16) and the camera (32) are directed at the surface (18) from the same direction.

3. The method according to claim 1 or 2, characterized in that, The first angle α at which the infrared light (16) strikes the surface (18) is: About 30 degrees, or Between 25 and 35 degrees, or Between 20 and 50 degrees.

4. Method according to one of the preceding claims, characterized in that, The second angle β of the camera (32) pointing towards the surface (18) is: About 45 degrees, or Between 40 and 50 degrees, or Between 30 and 60 degrees It is greater than the first angle α.

5. The method according to any one of the preceding claims, characterized in that, The infrared light (16) emitted by the infrared light source (14) forms a beam that is emitted along the beam direction (B) and includes a spatial component (P) that is perpendicular to the beam direction (B) and extends parallel to the surface (18) being inspected.

6. The method according to claim 5, characterized in that, The camera (32) has a field of view (F) and / or a line scan direction that extends parallel to the spatial component (P) of the light beam.

7. The method according to any one of the preceding claims, characterized in that, The infrared light (16): Located at the boundary of visible light, and / or It has a wavelength of approximately 850 nm.

8. The method according to any one of the preceding claims, characterized in that, The camera (32) is a monochrome camera and / or an infrared camera.

9. The method according to any one of the preceding claims, characterized in that, The camera (32) is a line scan camera.

10. The method according to any one of the preceding claims, characterized in that, The camera (32): Including band filters that allow wavelengths of approximately 850 nm to pass through, and / or Lens filters are not included.

11. The method according to any one of the preceding claims, characterized in that, The infrared light source (14) and the camera (32) are positioned above the top edge (54) of the part (12) during inspection, and a mirror (42) is positioned on one or both sides (55) of the part (12) such that the mirror (42) deflects the infrared light (16) onto the surface (18) at the first angle α, and the camera (32) is pointed at the mirror (42) so as to point at the surface (18) at the second angle β.

12. A system for surface inspection of a cured composite part (12) comprising glass fiber (22) and carbon fiber (26), the cured composite part (12) being particularly a cured composite part for an aircraft, wherein, The system (10) includes an infrared light source (14) and a camera (32), both of which are configured to perform the method according to any one of the preceding claims.

13. Use of an infrared light source (14) and a camera (32) in the method according to any one of claims 1 to 11.

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