Fluorescent penetrant flaw detection device

Abstract

Provided is a fluorescent penetrant flaw detection device capable of specifying the position of a flaw on a surface to be inspected while suppressing the occurrence of a false color in a captured image. The camera (40) is a monochromatic camera. Furthermore, the camera (40) performs the first imaging and the second imaging in a state in which the relative position, the relative angle, and the magnification are fixed with respect to the surface to be inspected (51). In the first imaging, imaging is performed without passing through the ultraviolet cut-off filter (48). In the second imaging, imaging via the ultraviolet cut filter (48) is performed. A CPU (11) (processor) extracts, as a fluorescent region (60), a region exceeding a predetermined surface luminosity threshold value from the image obtained by the second imaging. The CPU (11) overlaps the fluorescent region (60) on the image obtained by the first imaging.

Description

TECHNICAL FIELD

[0001] In the present specification, a fluorescent penetration inspection device is disclosed. BACKGROUND

[0002] In Patent Literature 1, a surface defect inspection device is disclosed. In the defect device, fluorescent penetration inspection is performed. Ultraviolet light is irradiated to an inspection surface to which a penetration treatment by a luminescent penetrating solution is applied. The inspection surface is captured by an image sensor. The captured data of the image sensor is digitally converted into RGB data. Further, the captured data is displayed as a color image.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Laid-Open No. 2018-179621 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] However, in a digital camera, in order to obtain a color image, a color filter is provided on an image sensor. For example, filter elements of red, green, and blue are arranged based on a Bayer arrangement.

[0008] For example, on the adjacent filter elements of red, filter elements of green or blue are provided. At the portions where the filter elements of green or blue are provided, the pixel value of red is not detected. Therefore, based on the pixel values in the adjacent filter elements of the same color, the pixel value of the portion sandwiched between the filter elements is estimated. This estimation is called an interpolation process.

[0009] For example, assume that the pixel value of one of the adjacent filter elements of red is 255, and the pixel value of the other is 0. In this case, 127 is calculated as the pixel value of red of the portion sandwiched between the filter elements.

[0010] Here, in a region where the contrast is high, there is a possibility that the pixel value 255 will be adjacent to the pixel value 0. In such a case, the pixel value 127 of red calculated by the interpolation process becomes a so-called false color. For example, in a captured image, the false color is expressed in a texture-like manner along the edge of an object.

[0011] Here, the false color of green, which is one of the constituent colors of the color filter, sometimes closely resembles the fluorescent color in the fluorescent penetration inspection. That is, there is a possibility that an erroneous determination that an output has a defect will be made due to the false color.

[0012] Therefore, in the present specification, a fluorescent penetrant inspection device capable of specifying the position of a scratch on an inspection surface while suppressing the generation of false colors in a captured image is disclosed.

[0013] Method for solving the problem

[0014] In the present specification, a fluorescent penetrant inspection device is disclosed. The device is provided with a camera, an inspection lamp, an ultraviolet cut filter, and a processor. The camera captures an inspection surface. The inspection lamp irradiates ultraviolet light to the inspection surface. The ultraviolet cut filter can be disposed on the optical axis of the camera. The processor processes a captured image of the camera. The camera is a monochrome camera. Also, the camera performs first capturing and second capturing in a state where the relative position, the relative angle, and the magnification are fixed with respect to the inspection surface. In the first capturing, capturing is performed without passing through the ultraviolet cut filter. In the second capturing, capturing is performed passing through the ultraviolet cut filter. The processor extracts a region exceeding a predetermined surface luminance threshold as a fluorescent region from an image obtained by the second capturing. Also, the processor superimposes the fluorescent region on an image obtained by the first capturing.

[0015] According to the above structure, the capturing of the inspection surface is performed using a monochrome camera. Thereby, since interpolation processing is not performed, false colors are suppressed. Also, in a case where the inspection surface is captured using a monochrome camera, it is difficult to distinguish reflected light of the inspection lamp from fluorescent light generated from the penetrant. Therefore, the first capturing without passing through the ultraviolet cut filter and the second capturing passing through the ultraviolet cut filter are performed. By the first capturing, it is possible to visually confirm the surface shape of the inspection surface. Also, by the second capturing, it is possible to specify the fluorescent region on the inspection surface. Also, by superimposing the fluorescent region on the first captured image, it is possible to grasp where the fluorescent region appears on the inspection surface.

[0016] Further, in the above structure, it can be configured that the processor performs color processing on the fluorescent region.

[0017] According to the above structure, the fluorescent region in the black and white image is easily found by the worker.

[0018] Further, in the above structure, it can be configured that when the ultraviolet cut filter is disposed on the optical axis, the camera and the ultraviolet cut filter are separated along the optical axis.

[0019] In a case where, for example, the ultraviolet filter is mounted on the lens barrel, the optical axis of the camera can be shaken at the time of mounting. By configuring the camera and the ultraviolet cut filter to be non-contact, the shaking of the optical axis is suppressed.

[0020] Further, in the above configuration, the fluorescent penetrant inspection device can be provided with a filter arm. The filter arm can move the ultraviolet cut filter toward and away from the optical axis of the camera.

[0021] According to the above configuration, the filter replacement work performed by the staff is no longer required.

[0022] Further, in the above configuration, the inspection lamp can be configured to increase the intensity of the irradiation at the time of the second photographing compared to the time of the first photographing.

[0023] According to the above configuration, the second photographing is performed under high-intensity illumination, and thus the fluorescent region can be visually confirmed with high clarity.

[0024] Effects of Invention

[0025] According to the fluorescent penetrant inspection device disclosed in the present specification, the position of a flaw on an inspected surface can be specified while suppressing the generation of false colors in a photographed image. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A perspective view illustrating the structure of the fluorescent penetrant inspection device according to the present embodiment.

[0027] Figure 2 A perspective view illustrating the structure of the camera periphery.

[0028] Figure 3 A diagram illustrating the hardware structure of the computer device.

[0029] Figure 4 A diagram illustrating the functional modules of the computer device.

[0030] Figure 5 A diagram illustrating the inspection flow.

[0031] Figure 6 A diagram illustrating the first photographed image.

[0032] Figure 7 A diagram illustrating the second photographed image.

[0033] Figure 8 A diagram illustrating the synthesized image. DETAILED DESCRIPTION

[0034] 1. Inspected body

[0035] In Figure 1 , the fluorescent penetrant inspection device according to the present embodiment is illustrated. Further, in Figure 1 , the inspected body 50 is illustrated.

[0036] In addition, an orthogonal coordinate system is shown in Figure 1 , Figure 2 . The orthogonal coordinate system is composed of a U-axis, an L-axis, and a W-axis. The U-axis is an upright direction axis. The L-axis and the W-axis extend on a horizontal plane. The L-axis and the W-axis are orthogonal. The L-axis is parallel to the 0° line of the base 22 of the robot arm 20.

[0037] The object 50 to be inspected is, for example, a cast product of aluminum. 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 that makes a frame and a panel of the vehicle body be integrally formed.

[0038] Since the object 50 to be inspected is a part of the frame of the vehicle body, the object 50 to be inspected requires a predetermined strength. For example, a plurality of ribs 52 and holes 54 are provided on the object 50 to be inspected. Along with this, the inspection surface 51 becomes a concave-convex shape. For example, at the time of assembling the object 50 to be inspected to the vehicle body, the inspection surface 51 becomes a part of a side surface of the vehicle body. At the time of performing a flaw detection inspection, the object 50 to be inspected is laid down, and thus the inspection surface 51 becomes an upper surface.

[0039] At the time of performing a flaw detection inspection, a bottom surface of the inspection surface 51 becomes an opposing surface 53 with respect to the camera 40. That is, the opposing surface 53 is disposed substantially perpendicularly with respect to an optical axis of the camera 40. For example, the opposing surface 53 intersects the optical axis of the camera in a range of 80° or more and 100° or less.

[0040] As a method of fluorescent flaw detection, a fluorescent magnetic particle flaw detection and a fluorescent penetrant flaw detection are known. The fluorescent magnetic particle flaw detection is not suitable for aluminum that is a non-magnetic body. Therefore, for the object to be inspected that is a cast product of aluminum, the fluorescent penetrant flaw detection can be applied.

[0041] In the fluorescent penetrant flaw detection, a penetrant solution is applied to the inspection surface 51. A fluorescent substance is added to the penetrant solution. After the penetrant solution is applied, the penetrant solution of the inspection surface 51 is removed after a predetermined time. Also, when ultraviolet rays are irradiated to the inspection surface 51, the penetrant solution (that is, not removed) that has penetrated into a flaw or a crack emits light.

[0042] 2. Fluorescent penetrant flaw detection device

[0043] In Figure 1 , Figure 2 , a robot arm 20 and a device supported by the arm are exemplified. The robot arm 20 supports a camera 40, a ring light 44, and an ultraviolet cut filter 48. The robot arm 20 is, for example, a four-axis multi-joint robot arm. The robot arm 20 has a base 22, a first arm 24, a second arm 26, and an auxiliary rod 28.

[0044] The base 22 has a base lower portion 22A and a base upper portion 22B. The base upper portion 22B is revolved around an axis Ll with respect to the base lower portion 22A. The axis Ll is parallel to a U-axis (vertical axis). The base upper portion 22B is revolved with respect to the base lower portion 22A by a servo motor (not shown), for example.

[0045] One end of a first arm 24 is connected to the base upper portion 22B. One end of a second arm 26 is connected to the other end of the first arm 24. Further, one end of an auxiliary rod 28 is connected to the other end of the second arm 26.

[0046] The first arm 24 is rotated around a rotation axis L2 with respect to the base upper portion 22B. The second arm 26 is rotated around a rotation axis L3 with respect to the first arm 24. Further, the auxiliary rod 28 is rotated around a rotation axis L4 with respect to the second arm 26. The rotation axes L2, L3, L4 each extend in a horizontal direction. Servo motors (not shown) are provided on the rotation axes L2, L3, L4.

[0047] The auxiliary rod 28 extends on an extension line of the second arm 26. A camera 40, a ring light 44, and an ultraviolet cut filter 48 are attached to the auxiliary rod 28. That is, the robot arm 20 moves the camera 40 and the ultraviolet cut filter 48 with respect to an object 50 to be inspected.

[0048] The camera 40 photographs the inspection surface 51 (refer to Figure 1 ) over a wide range. The camera 40 photographs the entire surface of the inspection surface 51 with one lens, for example. The camera 40 is a lens-replaceable camera, for example. A lens barrel 42 is attached to a lens holder of the camera 40. A top end of the lens barrel 42 supports an objective lens 46.

[0049] Further, the camera 40 is a monochrome camera. For example, no color filter is provided on an image sensor in the camera 40. The image sensor outputs a pixel value from 0 (black) to 255 (white) in accordance with the intensity of received light. Since the camera 40 is a monochrome camera, interpolation processing performed at the time of generation of a color digital image is not performed. Thus, in the fluorescent penetrant inspection apparatus according to the present embodiment, a monochrome image which does not cause a false color in principle is used instead of a color digital image which can cause a false color.

[0050] Refer to Figure 2The annular lamp 44 is an ultraviolet flaw detection lamp of a ring shape. The annular lamp 44 irradiates ultraviolet light toward the inspection surface 51. The camera 40 and the annular lamp 44 are positioned so that the center of the annular lamp 44 passes through the optical axis of the camera 40. The relative positions of the camera 40 and the annular lamp 44 are fixed.

[0051] The annular lamp 44 is, for example, a so-called UV ring lamp. The annular lamp 44 has a plurality of ultraviolet LEDs 45 as light sources. The plurality of ultraviolet LEDs 45 are arranged in a circular ring shape. The optical axis of the ultraviolet LED 45 is, for example, parallel to the optical axis of the camera 40.

[0052] From the ultraviolet LED 45, for example, UV-A waves are irradiated. The wavelength band of the UV-A waves is 315 nm to 400 nm. In contrast, it is known that the lower limit of the wavelength of visible light is 360 nm. That is, in the light irradiated from the annular lamp 44, a band component of visible light is included.

[0053] The irradiation intensity of the annular lamp 44 can be variable. For example, the annular lamp 44 changes the irradiation intensity between 0% and 100%. For example, the annular lamp 44 can switch between high intensity (for example, 100%) and low intensity (for example, 20%). The intensity is, for example, the unit of the radiation intensity, that is, the luminous flux W / sr. Alternatively, the radiation illuminance W / m 2 .

[0054] Referring to Figure 1 , Figure 2 The ultraviolet cut filter 48 is attached to the auxiliary rod 28. The ultraviolet cut filter 48 is attached to the auxiliary rod 28 via the filter arm 47.

[0055] The filter arm 47 is, for example, linearly extended in parallel to the optical axis of the camera 40. Further, the filter arm 47 has a movable portion 47A and a fixed portion 47B. In addition, the filter arm 47 has a servo motor (not shown) that rotates the movable portion 47A. The movable portion 47A rotates with respect to the fixed portion 47B with the rotation axis L5 as the rotation axis.

[0056] The ultraviolet cut filter 48 is attached to the tip end of the movable portion 47A. The filter arm 47 can move the ultraviolet cut filter 48 outside the optical axis of the camera 40 (out of the optical axis), and on the optical axis (on the optical axis) of the camera 40. In the on the optical axis configuration, the main surface of the ultraviolet cut filter 48 is orthogonal to the optical axis of the camera 40. Figure 1 Figure 2 Figure 2

[0057] ​​​Here, the ultraviolet cut filter 48 is separated from the camera 40 and the lens barrel 42 along the optical axis. That is, the lens barrel 42 and the ultraviolet cut filter 48 are non-contact. For example, if the ultraviolet cut filter 48 is to be attached to the lens barrel 42 by a fitting mechanism such as a snap fit, the optical axis of the camera 40 can be shaken in the inspection procedure described later. By making the ultraviolet cut filter 48 non-contact with the camera 40 and the lens barrel 42, the shaking of the optical axis of the camera 40 between the first imaging and the second imaging described later is suppressed. Referring to Figure 2 For example, the ultraviolet cut filter 48 is disposed between the objective lens 46 and the ring light 44.

[0058] The ultraviolet cut filter 48 cuts off, for example, wavelengths of 400 nm or less. As described above, the wavelength band of UV-A waves is 315 nm to 400 nm. That is, the visible light component of the UV-A waves is excluded by the ultraviolet cut filter 48.

[0059] Referring to Figure 1 The computer device 10 is connected to the robot arm 20, the camera 40, the ring light 44, and the filter arm 47. The computer device 10 controls these devices. In addition, the computer device 10 is connected to the display section 16 and the input device 17. Referring to Figure 1 The display section 16 is, for example, a display device. The input device 17 is, for example, a keyboard and a mouse.

[0060] Referring to Figure 3 The computer device 10 has a CPU 11, a RAM 12, a ROM 13, a storage 14, and an input / output controller 15.

[0061] The CPU 11 is a central processing device, also referred to as a processor. The RAM 12 is a volatile storage device that temporarily stores data during processing. The ROM 13 is a storage device that enables reading of data. The storage 14 is a storage device that enables writing and reading of data. The storage 14 is constituted by, for example, an HDD (Hard Disk Drive) or an SSD (Solid State Drive).

[0062] The function modules exemplified in the computer device 10 are constructed by the CPU 11 executing a program stored in the storage 14 or the ROM 13. Figure 4 The CPU 11 (processor) has a camera control section 18A, a robot arm control section 18B, an illumination control section 18C, and an image processing section 18E. These function modules execute Figure 5The illustrated flaw detection flow. That is, the CPU 11 processes the captured image of the camera 40 in accordance with the flaw detection flow.

[0063] 3. Flaw detection flow

[0064] Reference Figure 1 The object 50 to be inspected is disposed at a fixed position in order to perform flaw detection inspection. For example, a stage (not shown) is provided at the front of the robot arm 20. The object 50 to be inspected is placed on the stage. At the time of performing flaw detection inspection, the inspection surface 51 of the object 50 to be inspected is oriented upward.

[0065] Further, the impregnation liquid is applied to the inspection surface 51 by a worker or a spraying robot. After the impregnation liquid is applied, the impregnation liquid of the inspection surface 51 is removed after a predetermined time. When the impregnation liquid is removed, an instruction to start flaw detection inspection is sent from the input device 17 to the camera control section 18A. The instruction becomes a trigger, and thus the flaw detection flow of the camera control section 18A is started. Figure 5

[0066] Reference Figure 1 , Figure 4 , Figure 5 The camera control section 18A sends a movement instruction for capturing the inspection surface 51 to the robot arm control section 18B. The robot arm control section 18B controls the robot arm 20 so as to move the camera 40 to a capturing point (S10).

[0067] The robot arm control section 18B, for example, makes the geometric center of the inspection surface 51 coincide with the optical axis of the camera 40. Further, the robot arm control section 18B makes the optical axis of the camera 40 perpendicular with respect to the opposing surface 53 of the inspection surface 51 (refer to FIG. 2). Furthermore, the camera control section 18A separates the camera 40 from the inspection surface 51. The camera control section 18A, for example, separates the camera 40 from the inspection surface 51 in a range of, for example, 50 cm or more and 150 cm or less from the upper end of the inspection surface 51. Further, the camera control section 18A sets the photographing magnification in such a manner that the entire surface of the inspection surface 51 enters the field of view of the camera 40. Figure 1 When the camera 40 is disposed at the capturing point and the above-described capturing setting is completed, the robot arm control section 18B sends a movement completion notification to the camera control section 18A. Upon receiving the movement completion notification, the camera control section 18A sends an instruction to capture the inspection surface 51 to the camera 40 and the illumination control section 18C.

[0068]

[0069] ​​Camera 40 takes at least two photos of the surface 51 to be inspected. During these multiple shots, the relative position, relative angle, and magnification of camera 40 relative to the surface 51 to be inspected are fixed. For example, from step S12 to step S16, the relative position, relative angle, and magnification of camera 40 relative to the surface 51 to be inspected are fixed.

[0070] The fluorescent penetrant testing device performs imaging without passing through the ultraviolet cutoff filter 48 (first imaging) and imaging with passing through the ultraviolet cutoff filter 48 (second imaging). For example, the imaging conditions, other than the presence or absence of the ultraviolet cutoff filter 48, do not change for the first and second imaging. Alternatively, the illumination intensity of the ring lamp 44 may be changed in addition to the presence or absence of the ultraviolet cutoff filter 48 in the first and second imaging.

[0071] For example, in the first shot, the ultraviolet cutoff filter 48 is moved out of the optical axis of the camera 40 by the filter arm 47. In this state, the camera 40 takes a picture of the surface 51 being inspected (S12). Camera control unit 18A (see reference) Figure 4 After the first shot, a movement command is sent to the robotic arm control unit 18B. Upon receiving the movement command, the robotic arm control unit 18B rotates the filter arm 47. As a result, the ultraviolet cut-off filter 48 is positioned on the optical axis of the camera 40 (S14).

[0072] The robotic arm control unit 18B sends a movement completion command to the camera control unit 18A. Upon receiving this command, the camera control unit 18A sends a shooting command to the lighting control unit 18C and the camera 40. Furthermore, a second shot is taken via the camera 40.

[0073] exist Figure 6 The image obtained by the first shot is illustrated below. In the first shot, the surface to be inspected is illuminated by the fluorescence generated by the flaw detector and the visible light component of the ring lamp 44. Therefore, the image of the surface to be inspected 51 is displayed more clearly (compared to the second shot).

[0074] Furthermore, as mentioned above, camera 40 is a monochrome camera. Therefore, the image obtained from the first shot (the first shot image) becomes a grayscale image. In this case, it is more difficult to distinguish between the fluorescence produced by the flaw detector and the visible light component of the ring lamp 44.

[0075] In order to distinguish the fluorescence produced by the flaw detector from the visible light component of the ring lamp 44, a second image is taken (S16). Figure 7As exemplified, in the second photographing, the fluorescent region 60 has a surface luminance that can be visually confirmed. On the other hand, the region other than the fluorescent region 60 becomes a dark region that is difficult to visually confirm.

[0076] Here, in the second photographing, the irradiation intensity of the ring light 44 can be made higher than in the first photographing. By irradiating the inspection surface 51 with high intensity, the fluorescent region 60 can be sharply photographed. Further, in the second photographing, the visible light component of the ring light 44 is excluded by the ultraviolet cut filter 48. Therefore, the flare of the inspection surface 51 caused by the visible light component is suppressed.

[0077] Thus, the first photographing image is obtained by the first photographing. In the first photographing image, although the image of the inspection surface 51 can be sharply obtained, the distinction between the visible light component of the ring light 44 and the fluorescence of the flaw detection agent is difficult. Further, the second photographing image is obtained by the second photographing. In the second photographing image, although the fluorescence of the flaw detection agent can be visually confirmed, it is not clear where the fluorescence appears on the inspection surface 51.

[0078] As described above, throughout the first photographing and the second photographing, the relative position, the relative angle, and the photographing magnification of the camera 40 with respect to the inspection surface 51 are fixed. Therefore, if the first photographing image and the second photographing image are overlapped, it is possible to specify where the fluorescence appears on the inspection surface 51.

[0079] Referring to Figure 5 , the image processing section 18E extracts the fluorescent region 60 from the second photographing image (S18). For example, the image processing section 18E extracts, as the fluorescent region 60, the region in the second photographing region that exceeds a predetermined surface luminance threshold value.

[0080] Further, the image processing section 18E superimposes the fluorescent region 60 on the first photographing image (S20). As described above, throughout the first photographing and the second photographing, the relative position, the relative angle, and the photographing magnification of the camera 40 with respect to the inspection surface 51 are fixed. That is, the origin position and the coordinate scale of the local coordinate system in the first photographing image and the origin position and the coordinate scale of the local coordinate system in the second photographing image are the same in the general coordinate system. Therefore, by drawing the fluorescent region 60 on the coordinate plane of the first photographing image, the Figure 8 exemplified synthesized image 65 is generated.

[0081] In addition, the coloring processing of the fluorescent region 60 can also be performed between the step S18 and the step S20. For example, the image processing section 18E imparts a predetermined fluorescent color to the fluorescent region 60. Thereby, in the composite image 65, the fluorescent region 60 of the fluorescent color is overlaid on the first captured image of the gray scale. That is, the visibility of the fluorescent region 60 is enhanced.

[0082] The image processing section 18E displays the composite image 65 on the display section 16 (refer to Figure 1 ) (S22). By the composite image 65, the worker can visually confirm which part of the inspected surface 51 has the scratch.

[0083] Symbol explanation

[0084] 10... computer device; 11... CPU (processor); 18A... camera control section; 18B... robot control section; 18C... illumination control section; 18E... image processing section; 20... robot; 28... auxiliary rod; 40... camera; 42... lens barrel; 44... ring light; 45... ultraviolet LED; 46... objective lens; 47... filter arm; 48... ultraviolet cut filter; 50... inspected object; 51... inspected surface; 60... fluorescent region; 65... composite image.

Claims

1. A fluorescent penetrant inspection apparatus, comprising: a camera that photographs an inspection surface; an inspection lamp that irradiates ultraviolet light to the inspection surface; an ultraviolet cut filter that is capable of being disposed on an optical axis of the camera; a processor that processes a photographed image of the camera, wherein the camera is a monochrome camera, wherein the camera performs first photographing without the ultraviolet cut filter and second photographing with the ultraviolet cut filter in a state in which a relative position, a relative angle, and a magnification are fixed with respect to the inspection surface, wherein the processor performs processing in which: a region that exceeds a predetermined surface luminance threshold value is extracted as a fluorescent region from an image obtained by the second photographing, and the fluorescent region is superimposed on an image obtained by the first photographing.

2. The fluorescent penetrant inspection apparatus according to claim 1, wherein the processor performs color processing on the fluorescent region.

3. The fluorescent penetrant inspection apparatus according to claim 1, wherein the camera is separated from the ultraviolet cut filter along the optical axis when the ultraviolet cut filter is disposed on the optical axis.

4. The fluorescent penetrant inspection apparatus according to claim 3, comprising a filter arm that is capable of moving the ultraviolet cut filter to the optical axis of the camera and outside the optical axis.

5. The fluorescent penetrant inspection apparatus according to any one of claims 1 to 4, wherein the inspection lamp increases an irradiation intensity at the time of photographing of the second photographing compared to the time of photographing of the first photographing. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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