Fluorescent penetrant inspection system

Abstract

To provide a fluorescent penetrant inspection system capable of irradiating flaw detection light just enough on the uneven surface to be inspected.SOLUTION: A ring light 44 (ultraviolet flaw detection light) encloses an objective lens 46 of a camera 40. The camera 40 captures images of the surface 51 to be inspected at least twice, with the relative position, relative angle, and magnification fixed with respect to the surface 51. The ring light 44 has a fixed relative position and angle with respect to the surface 51 to be inspected, and is configured to make the intensity of the flaw detection light different between the first and second images taken by the camera 40.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] Disclosed herein is a fluorescent penetrant inspection device.

[0002] Patent Documents 1 and 2 disclose visual inspection devices. In Patent Document 1, a fluorescent agent is permeated into the surface of an object to be inspected. After a predetermined time, the fluorescent agent is removed from the surface of the object to be inspected. Then, ultraviolet light is irradiated onto the object to be inspected. If the object to be inspected has a flaw, the fluorescent agent that has permeated into the flaw (i.e., not been removed) will emit light when irradiated with ultraviolet light. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-83285 [Patent Document 2] Japanese Patent Application Publication No. 7-113625 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the surface to be inspected has an uneven shape, parts of the surface act as walls that block ultraviolet light, resulting in shadow areas on the surface to be inspected. This can lead to insufficient fluorescence emission in the shadow areas.

[0005] On the other hand, if the irradiation intensity of the flaw detection light is too strong in order to irradiate the shadow area, the flaw detection light will be excessively irradiated to areas other than the shadow area. The flaw detection light may contain visible light components. Therefore, excessive irradiation of the flaw detection light may cause halation on part of the surface to be inspected.

[0006] Therefore, this specification discloses a fluorescent penetrant flaw detection device that can irradiate flaw detection light just enough onto an uneven surface to be inspected. [Means for solving the problem]

[0007] This specification discloses a fluorescent penetrant inspection device. The device includes a camera and an ultraviolet inspection lamp. The camera captures an image of an unevenly shaped surface to be inspected. The ultraviolet inspection lamp is ring-shaped and surrounds the objective lens of the camera. The camera captures images of the surface to be inspected at least twice while the relative position, relative angle, and magnification are fixed. The ultraviolet inspection lamp changes the intensity of the inspection light between the first and second images taken by the camera while the relative position and relative angle are fixed with respect to the surface to be inspected.

[0008] With the above configuration, it is possible to detect flaws in areas other than those causing halation based on a high-light illumination image where the searchlight intensity is relatively high, and it is also possible to detect flaws in areas that caused halation in the high-light illumination image based on a low-light illumination image where the searchlight intensity is relatively low.

[0009] In the above configuration, the fluorescent penetrant flaw detection device may further include a processor. The processor processes the image captured by the camera. The processor extracts the opposing surface area of ​​the surface to be inspected from the low-light image. The low-light image refers to an image in which the flaw detection light is of relatively low intensity. The opposing surface area refers to the area facing the ultraviolet flaw detection lamp. Furthermore, the processor extracts an image area other than the opposing surface area from the high-light image. The high-light image refers to an image in which the flaw detection light is of relatively high intensity.

[0010] When an ultraviolet searchlight is irradiated at high intensity, halation easily occurs on the surface being inspected. With the above configuration, the opposing surface area where halation easily occurs can be excluded from the high-intensity illumination image. Also, the presence or absence of scratches in the opposing surface area can be determined from the low-intensity illumination image.

[0011] In the above configuration, the processor may identify the opposing surface area based on design drawing data of the surface to be inspected.

[0012] In a captured image where halation occurs, the boundary line (outline) between the opposing surface area and the adjacent area becomes unclear. According to the above configuration, by specifying the opposing surface area in advance based on design drawing data, the opposing surface area can be accurately extracted from the captured image.

[0013] In the above configuration, the processor may generate a composite image by combining an image region extracted from the high-illumination image and an image region extracted from the low-illumination image.

[0014] According to the above configuration, the flaw detection location can be visually recognized in one image. [Effects of the Invention]

[0015] The fluorescent penetrant flaw detection device disclosed in this specification makes it possible to irradiate the uneven surface to be inspected with just the right amount of flaw detection light. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a perspective view illustrating the configuration of a fluorescent penetrant flaw detection device according to an embodiment of the present invention. [Figure 2] FIG. 1 is a perspective view illustrating the structure of a robot arm, a camera, and a ring light. [Figure 3] FIG. 1 is a diagram illustrating an example of a hardware configuration of a computer device. [Figure 4] FIG. 2 is a diagram illustrating an example of functional blocks of a computer device. [Figure 5] FIG. 10 is a diagram illustrating a flaw detection flow. [Figure 6] FIG. 10 is a diagram illustrating an example of a strongly illuminated image. [Figure 7] FIG. 1 is a diagram illustrating a low-light image. [Figure 8] FIG. 10 is a diagram showing an example of extracting a region (wall region) other than the opposing surface region from a strong illumination image. [Figure 9] 10A and 10B are diagrams illustrating an example of extracting an opposing surface area from a low-light image. [Figure 10] FIG. 1 is a schematic diagram illustrating a synthetic image generation process. DETAILED DESCRIPTION OF THE INVENTION

[0017] 1. Test object 1 illustrates a fluorescent penetrant flaw detection device according to this embodiment, and also illustrates an object 50 to be inspected.

[0018] 1 and 2 show a Cartesian coordinate system. This Cartesian coordinate system is composed of a U-axis, an L-axis, and a W-axis. The U-axis is a vertical axis. The L-axis and the W-axis extend on a horizontal plane. The L-axis and the W-axis are perpendicular to each other. The L-axis is parallel to the 0° line of the base 22 of the robot arm 20.

[0019] The object 50 to be inspected is, for example, an aluminum casting. The object 50 to be inspected constitutes, for example, a part of a vehicle body. The object 50 to be inspected is a large cast product in which the frame and panels of the vehicle body are integrally molded.

[0020] Since the object 50 to be inspected is part of the vehicle body frame, the object 50 to be inspected is required to have a certain level of strength. For example, the object 50 to be inspected is provided with a plurality of ribs 52 and holes 54. Accordingly, the surface 51 to be inspected has an uneven shape. For example, when the object 50 to be inspected is assembled to a vehicle body, the surface 51 to be inspected becomes part of the side surface of the vehicle body. In other words, during flaw detection inspection, the object 50 to be inspected is laid down, with the surface 51 to be inspected facing upward.

[0021] During flaw detection testing, the bottom surface of the surface to be inspected 51 serves as the opposing surface 53 to the camera 40. In other words, the opposing surface 53 is disposed approximately perpendicular to the optical axis of the camera 40. For example, the opposing surface 53 intersects with the optical axis of the camera at an angle between 80° and 100°. This angle is also called the "observation angle."

[0022] Known fluorescent flaw detection methods include fluorescent magnetic particle testing and fluorescent penetrant testing. Fluorescent magnetic particle testing is not suitable for aluminum, which is a non-magnetic material. Therefore, fluorescent penetrant testing is applied to inspected aluminum castings.

[0023] In fluorescent penetrant testing, a penetrant is applied to the surface 51 to be inspected. A fluorescent substance is added to the penetrant. After the penetrant is applied, the penetrant is removed from the surface 51 to be inspected after a predetermined time. When ultraviolet light is further irradiated onto the surface 51 to be inspected, the penetrant that has soaked into scratches and cracks (i.e., that has not been removed) emits light.

[0024] As will be described later, when camera 40 captures an image of inspection surface 51, ultraviolet light is irradiated from ring light 44. At this time, as rib 52 becomes longer, part of the ultraviolet light is blocked by the walls of hole 54 and rib 52 on inspection surface 51. As illustrated in FIG. 7 , the area where the ultraviolet light is blocked is called a shadow area 59.

[0025] 2. Fluorescent penetrant inspection equipment 2 illustrates a robot arm 20 and devices supported by the arm. The robot arm 20 supports a camera 40 and a ring light 44. The robot arm 20 is, for example, a four-axis articulated robot. The robot arm 20 includes a base 22, a first arm 24, a second arm 26, and an attachment bar 28.

[0026] The base 22 includes a lower base portion 22A and an upper base portion 22B. The upper base portion 22B rotates about an axis L1 relative to the lower base portion 22A. The axis L1 is parallel to the U-axis (vertical axis). For example, the upper base portion 22B rotates relative to the lower base portion 22A by a servo motor (not shown).

[0027] One end of a first arm 24 is connected to the upper base portion 22B. One end of a second arm 26 is connected to the other end of the first arm 24. Furthermore, an attachment bar 28 is connected to the other end of the second arm 26.

[0028] The first arm 24 rotates about a rotation axis L2 relative to the upper base portion 22B. The second arm 26 rotates about a rotation axis L3 relative to the first arm 24. Furthermore, the attachment bar 28 rotates about a rotation axis L4 relative to the second arm 26. The rotation axes L2, L3, and L4 each extend horizontally. Servo motors (not shown) are provided on the rotation axes L2, L3, and L4.

[0029] The attachment bar 28 extends on an extension line of the second arm 26. A camera 40 and a ring light 44 are attached to the attachment bar 28. That is, the robot arm 20 moves the camera 40 and the ring light 44 relative to the object 50 under inspection.

[0030] Camera 40 captures an image of a wide area of ​​surface 51 to be inspected (see FIG. 1). For example, camera 40 captures an image of the entire surface 51 to be inspected in one shot. For example, camera 40 is a camera with interchangeable lenses. A lens barrel 42 is attached to the lens mount of camera 40. The tip of lens barrel 42 supports an objective lens 46.

[0031] A ring light 44 is attached to the attachment bar 28 so as to surround the objective lens 46. The ring light 44 is a ring-shaped ultraviolet flaw detection lamp. The camera 40 and the ring light 44 are positioned so that the center of the ring light 44 passes through the optical axis of the camera 40. The relative positions of the camera 40 and the ring light 44 are fixed.

[0032] For example, the ring light 44 is a so-called UV ring light. The ring light 44 includes a plurality of ultraviolet LEDs 45 as a light source. The plurality of ultraviolet LEDs 45 are arranged in a circular ring shape. The optical axis of the ultraviolet LEDs 45 is parallel to the optical axis of the camera 40, for example.

[0033] The ultraviolet LED 45 irradiates, for example, UV-A rays. The wavelength band of UV-A rays is 315 nm to 400 nm. In contrast, the lower limit of the wavelength of visible light is known to be 360 ​​nm. In other words, the light irradiated from the ring light 44 contains components in the wavelength band of visible light. Therefore, when the inspection surface 51 is irradiated with high intensity light, halation occurs on the opposing surface 53, as illustrated in FIG. 6.

[0034] Halation is also called whiteout. Halation makes it difficult to visually recognize the fluorescent light emitted from the opposing surface 53. Halation also makes the boundary between the opposing surface 53 and its adjacent area unclear.

[0035] The illumination intensity of the ring light 44 may be variable. For example, the illumination intensity of the ring light 44 varies between 0% and 100%. For example, the ring light 44 can be switched between two intensities: high intensity (for example, 100%) and low intensity (for example, 20%). For example, the intensity refers to luminous intensity [W / sr], which is a unit of radiation intensity. Alternatively, the irradiance [W / m 2 ] may also be used.

[0036] 1, a computer device 10 is connected to a robot arm 20, a camera 40, and a ring light 44. The computer device 10 controls these devices. The computer device 10 is also connected to a display unit 16 and an input device 17. Referring to FIG. 1, the display unit 16 is, for example, a display device. The input device 17 is, for example, a keyboard or a mouse.

[0037] Referring to FIG. 3, the computer device 10 includes a CPU 11, a RAM 12, a ROM 13, a storage 14, and an input / output controller 15.

[0038] The CPU 11 is a central processing unit, also called a processor. The RAM 12 is a volatile storage device that temporarily stores data during operation. The ROM 13 is a storage device from which data can be read. The storage 14 is a storage device from which data can be written and read. The storage 14 is configured, for example, by an HDD (Hard Disk Drive) or an SSD (Solid State Drive).

[0039] 4 is constructed in the computer device 10 by the CPU 11 executing a program stored in the storage 14 or the ROM 13. The CPU 11 (processor) includes a camera control unit 18A, a robot control unit 18B, a lighting control unit 18C, an image processing unit 18E, and a flaw determination unit 18F. These functional blocks execute the flaw detection flow illustrated in FIG.

[0040] Furthermore, at least a part of the storage area of ​​the ROM 13 or the storage 14 is allocated to a design drawing data storage unit 18D. Design drawing data of the surface 51 to be inspected is stored in the design drawing data storage unit 18D.

[0041] The design drawing data is, for example, three-dimensional data. In the design drawing data, the inspected surface 51 is classified into parts such as ribs 52, holes 54, and opposing surface 53 (bottom surface).

[0042] 3. Flaw detection flow 1, the object 50 to be inspected is placed at a fixed position for flaw detection inspection. For example, a stage (not shown) is provided in front of the robot arm 20. The object 50 to be inspected is placed on this stage. For flaw detection inspection, the surface 51 to be inspected of the object 50 to be inspected faces upward.

[0043] Furthermore, a penetrant is applied to the surface 51 to be inspected by an operator or a painting robot. After the penetrant is applied, the penetrant is removed from the surface 51 to be inspected after a predetermined time. Once the penetrant is removed, a command to start the flaw detection inspection is sent from the input device 17 to the camera control unit 18A. This command triggers the start of the flaw detection flow shown in FIG. 5.

[0044] 1, 4, and 5, camera control unit 18A transmits to robot control unit 18B a movement command to capture an image of inspection surface 51. Robot control unit 18B controls robot arm 20 to move camera 40 to the imaging point (S10).

[0045] For example, the robot control unit 18B aligns the optical axis of the camera 40 with the geometric center of the surface 51 to be inspected. Furthermore, the robot control unit 18B makes the optical axis of the camera 40 perpendicular to the opposing surface 53 of the surface 51 to be inspected (see FIG. 1). Furthermore, the camera control unit 18A separates the camera 40 from the surface 51 to be inspected. For example, the camera control unit 18A separates the camera 40 from the surface 51 to be inspected by a distance of 50 cm to 150 cm from the top end of the surface 51 to be inspected. Furthermore, the camera control unit 18A sets the magnification so that the entire surface 51 to be inspected is within the field of view of the camera 40. The magnification may be set by the operator. The set magnification may be saved as a fixed value.

[0046] When the camera 40 is placed at the imaging point and the imaging setting is completed, the robot control unit 18B transmits a movement completion notification to the camera control unit 18A. Upon receiving the movement completion notification, the camera control unit 18A transmits a command to the camera 40 and the illumination control unit 18C to image the inspection surface 51.

[0047] The camera 40 captures images of the surface 51 to be inspected at least twice. In these multiple captures, the relative position, relative angle, and imaging magnification of the camera 40 with respect to the surface 51 to be inspected are fixed. For example, from step S12 to step S18, the relative position, relative angle, and imaging magnification of the camera 40 with respect to the surface 51 to be inspected are fixed. In addition, the ring light 44 changes the intensity of the flaw detection light between the first and second captures. In other words, in multiple captures, all conditions except the intensity of the ring light 44 are fixed.

[0048] The illumination control unit 18C sets the intensity of the ring light 44 when capturing an image of the inspection surface 51. For example, when capturing an image for the first time, the illumination control unit 18C sets the radiation intensity of the ring light 44 to high (S12).

[0049] Camera 40 captures an image of inspection surface 51 illuminated by ring light 44 (S14). The image of inspection surface 51 captured under relatively strong illumination will be referred to as a strong illumination image hereinafter. FIG. 6 shows an example of strong illumination image 55A captured by camera 40.

[0050] For example, as described above, the light source of the ring light 44 may be an ultraviolet LED 45 (see FIG. 2). The ultraviolet LED 45 is known to have a strong linearity. Therefore, a high-intensity light beam is irradiated onto the opposite surface 53 of the inspection surface 51, which faces the ring light 44 (ultraviolet flaw detection lamp). Since the flaw detection light contains visible light components, halation (white spots) occurs on the opposite surface 53 in the high-intensity illumination image 55A, as illustrated in FIG. 6.

[0051] Due to the high brightness of the opposing surface 53, it is difficult to visually recognize scratches on the opposing surface 53. On the other hand, scratches 56A formed on the side wall of the rib 52 or the like due to the reflected light or diffused light from the opposing surface 53 can be visually recognized in the strong illumination image 55A.

[0052] Next, the illumination control unit 18C sets the radiation intensity of the ring light 44 to low (S16) when capturing the second image of the inspection surface 51.

[0053] The camera 40 captures an image of the inspection surface 51 illuminated with low illumination by the ring light 44 (S18). The image of the inspection surface 51 captured under relatively low illumination will be referred to as a low illumination image hereinafter.

[0054] 7 shows an example of low-light image 55B captured by camera 40. In low-light image 55B, just the right amount of flaw detection light is irradiated onto opposing surface 53. For example, flaw 56B formed on opposing surface 53 can be seen in the low-light image. Meanwhile, the side surface of rib 52 is a shadow area 59. Therefore, flaw 56A, which is visible in strong-light image 55A (see FIG. 6), is difficult to see in low-light image 55B.

[0055] The high-light image 55A and the low-light image 55B are transmitted to the image processor 18E. The image processor 18E extracts an image region other than the opposing surface region from the high-light image 55A (see FIG. 6). That is, the image processor 18E extracts a wall region 57A (see FIG. 8) from the high-light image 55A (S20). The wall region 57A includes the ribs 52 and the cylindrical wall of the hole 54. For example, the wall region 57A is extracted by removing the opposing surface 53 from the high-light image 55A.

[0056] In the strong illumination image 55A, halation occurs on the opposing surface 53, making the boundary between adjacent regions unclear. Therefore, based on the design drawing data of the inspection object 50, the image processing unit 18E identifies the opposing surface 53 in the strong illumination image 55A.

[0057] For example, the image processing unit 18E acquires an image of the inspected surface 51 from the design drawing data storage unit 18D. For example, the image processing unit 18E acquires an image of the inspected surface 51 from the design drawing data storage unit 18D, the image having the same angle and magnification as the camera 40 views the inspected surface 51.

[0058] In the design drawing data of the inspected surface 51, parts such as ribs 52, holes 54, and opposing surface 53 are labeled. Image processing unit 18E performs pattern matching between the strong-illumination image 55A and the design drawing data to identify opposing surface 53 in the strong-illumination image 55A. Image processing unit 18E then removes opposing surface 53 from the strong-illumination image 55A. This extracts image data of wall region 57A.

[0059] Next, image processing unit 18E extracts facing surface region 57B (see FIG. 9) from low-lighting image 55B (S22). For example, image processing unit 18E performs pattern matching between low-lighting image 55B and blueprint data to identify facing surface 53 in low-lighting image 55B. Image processing unit 18E then extracts facing surface 53 from low-lighting image 55B. This extracts image data of facing surface region 57B.

[0060] Image data of wall region 57A extracted from high-light image 55A and image data of opposing surface 53 extracted from low-light image 55B are sent to defect determination unit 18F. Defect determination unit 18F determines whether or not there is a defect in each image data (S24). For example, defect determination unit 18F extracts pixels with a predetermined brightness or higher by binarization processing and determines that the pixel is a defect.

[0061] 10, the flaw determination unit 18F highlights the detected flaws 56A and 56B (S26). For example, the flaw determination unit 18F superimposes a highlight frame 58 surrounding the flaws 56A and 56B on each image.

[0062] Next, flaw determination unit 18F generates composite image 60 (see the lower part of FIG. 10). Composite image 60 is generated by combining (combining) the image of wall region 57A and the image of opposing surface region 57B (S28). In the composite image, flaw 56A in high-light image 55A and flaw 56B in low-light image 55B are displayed on a single screen (S30). This composite image 60 is displayed on display unit 16 (see FIG. 1).

[0063] 5, the intensity of the ring light 44 was switched between high and low, and the inspection surface 51 was imaged twice. Alternatively, the number of times the image was captured may be one. In this case, a fluorescent band-pass filter (not shown) is attached to the camera 40.

[0064] A fluorescence bandpass filter has high transmittance in the fluorescence wavelength band. It also has high blocking performance in wavelength bands other than the fluorescence wavelength band. Therefore, for example, by attaching a bandpass filter in front of an objective lens, it is possible to suppress halation in captured images. [Explanation of symbols]

[0065] 10 Computer device, 11 CPU (processor), 18A Camera control unit, 18B Robot control unit, 18C Lighting control unit, 18D Blueprint data storage unit, 18E Image processing unit, 18F Flaw detection unit, 20 Robot arm, 40 Camera, 42 Lens barrel, 44 Ring light (ultraviolet flaw detection lamp), 45 Ultraviolet LED, 46 Objective lens, 50 Inspected object, 51 Inspected surface, 53 Opposing surface, 55A High-light image, 55B Low-light image, 56A, 56B Flaw, 57A Wall area, 57B Opposing surface area, 58 Highlighted frame, 59 Shadow area, 60 Composite image.

Claims

1. A fluorescent penetrant inspection device, a camera for capturing an image of an uneven surface to be inspected; a ring-shaped ultraviolet flaw detection lamp surrounding the objective lens of the camera; Equipped with the camera captures an image of the surface to be inspected at least twice while keeping a fixed relative position, a fixed relative angle, and a fixed magnification with respect to the surface to be inspected; The ultraviolet flaw detection lamp is configured to change the intensity of flaw detection light between the first image capture and the second image capture by the camera while the relative position and the relative angle with respect to the surface to be inspected are fixed. Fluorescent penetrant inspection equipment.

2. The fluorescent penetrant flaw detection device according to claim 1, a processor for processing the captured image of the camera; The processor: extracting an opposing surface area of ​​the surface to be inspected that faces the ultraviolet flaw detection lamp in a low-illumination image in which the flaw detection light has a relatively low intensity; extracting an image region other than the opposing surface region from a high-intensity illumination image in which the flaw detection light is relatively high intensity; Fluorescent penetrant inspection equipment.

3. The fluorescent penetrant flaw detection device according to claim 2, the processor identifies the opposing surface area based on design drawing data of the inspection target surface. Fluorescent penetrant inspection equipment.

4. The fluorescent penetrant flaw detection device according to claim 2 or 3, the processor generates a composite image by combining the image region extracted from the high-light image and the image region extracted from the low-light image. Fluorescent penetrant inspection equipment.

Images