JP2017173251A - Flaw detector, and method for detecting defect by flaw detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flaw detector whose defect detection rate is heightened, and a method for detecting a defect by the flaw detector.SOLUTION: Provided is a magnetic particle flaw detector comprising a camera for photographing an object to be inspected, and a detection device for detecting a defect in the object to be inspected from an original image acquired by the camera, wherein the detection device includes a defect determination unit which, when in a width calculation area Lc having a predetermined length in the long axis direction of a defect candidate part 43 extracted from the original image, the defect candidate part 43 fits in between two straight lines s1, s2 parallel to the long axis direction of the defect candidate part 43 and the distance (width w) between the two straight lines s1, s2 falls within a predetermined range, determines that the defect candidate part 43 is a defect.SELECTED DRAWING: Figure 9

Description

  The present disclosure relates to a flaw detection apparatus and a defect detection method using the flaw detection apparatus. More specifically, the present disclosure relates to a flaw detection apparatus capable of mechanically detecting a defect of an inspection object and a defect detection method using the flaw detection apparatus.

  A flaw detection inspection of the surface of an inspection object having ferromagnetism such as a steel material is performed by a magnetic particle flaw inspection, a penetrant flaw inspection, or the like, which is a kind of nondestructive inspection method. Among these, magnetic particle flaw detection is one of the most effective methods for detecting defects (cracks) that are harmful flaws on the surface of an object to be inspected.

  When a steel material is magnetized by applying a magnetic field to the steel material, the magnetic flux is disturbed due to a flaw in the steel material, and a part of the magnetic material leaks into the air as a leakage magnetic flux. At this time, if magnetic powder or a magnetic powder containing magnetic powder is present on the surface of the steel material, the magnetic powder is attracted to the leaked magnetic flux to form an indication pattern of the magnetic powder. In the magnetic particle inspection, the defect is inspected by observing the magnetic particle indicating pattern.

  On the other hand, in penetrant flaw detection, penetrating liquid is penetrated into defects such as cracks or pinholes opened on the surface of the object to be inspected, and developer powder is applied to the surface from which the surplus penetrating liquid has been removed. From the defect, a permeation indication pattern is formed by the permeated liquid sucked to the surface by capillary action. The penetration flaw inspection is to inspect the defect by observing the penetration instruction pattern.

  These flaw detection inspections are expected to improve productivity, reduce costs, improve quality, and the like by being automated. Attempts have been made to automate a flaw detection apparatus that captures the above-described instruction pattern with a camera and detects a defect by image processing.

  Japanese Patent Laid-Open No. 2004-26883 discloses a magnetizing part that generates a rotating magnetic field near the surface layer part of an object to be inspected, and flaw detection that corrects shading of an image photographed by a camera while the rotating magnetic field is being generated and detects flaws in all directions. There is disclosed a magnetic particle flaw detector having a portion.

JP 2011-038796 A

  According to the configuration of Patent Document 1, it is possible to observe a magnetic particle indicating pattern in a rotating magnetic field, and it is possible to stably detect a shallow depth that has been overlooked conventionally, so that the detection accuracy of a flaw portion is improved, It is said that there is an effect that the productivity of the inspection object is improved. However, since the magnetic particle indicating pattern is also formed in a magnetic discontinuity portion that does not become a defect in the object to be inspected or a surface shape change portion, it is not easy to distinguish these portions from defects.

  Accordingly, an object of the present disclosure is to provide a flaw detection apparatus with an increased defect detection rate and a defect detection method using the flaw detection apparatus.

  In order to solve the above-described problem, the present disclosure provides a flaw detection apparatus including: an input device that images an inspection object; and a detection device that detects a defect of the inspection object from an original image acquired by the input device. In the width calculation region having a predetermined length in the major axis direction of the defect candidate portion extracted from the original image, the detection apparatus is between two straight lines parallel to the major axis direction of the defect candidate portion. It has a defect determination unit that determines the defect candidate part as the defect when the defect candidate part is contained and the distance (width) between two straight lines is within a predetermined range.

  Further, the width calculation region includes a center of gravity of the defect candidate portion.

  The detection apparatus binarizes the original image with a first threshold value to extract a first defect candidate portion, and generates an inspection region so that the first defect candidate portion is included. An inspection region generation unit that performs the above processing, and a second extraction unit that binarizes the inspection region with a second threshold value that is smaller than the first threshold value and extracts a second defect candidate portion, The defect candidate portion is a region in which the second defect candidate portion is expanded.

  Further, the inspection area is an area surrounded by a rectangle enlarged by a predetermined width from a minimum rectangle including the first defect candidate portion.

  Further, the expansion process is a process of expanding the second defect candidate portion in at least the major axis direction.

  The flaw detection apparatus is a magnetic particle flaw detection apparatus further comprising a magnetic powder spraying device that applies magnetic powder to the inspection object, and a magnetization device that magnetizes the inspection object to form a magnetic particle instruction pattern by a leakage magnetic flux. And

  Furthermore, the length of the width calculation region is 0.3 mm or more and 10 mm or less.

  Further, the present disclosure provides the defect detection method according to the flaw detection apparatus in which the input device images the inspection object and the detection device detects the defect of the inspection object from the original image acquired by the input device. In a width calculation region having a predetermined length in the major axis direction of the defect candidate portion extracted from the original image, the defect determination unit included in the apparatus is parallel to the major axis direction of the defect candidate portion. The defect candidate portion is determined to be the defect when the defect candidate portion fits between the straight lines and the distance (width) between the two straight lines is within a predetermined range.

  Further, the width calculation region includes a center of gravity of the defect candidate portion.

  A first extraction unit further included in the detection device binarizes the original image with a first threshold value to extract a first defect candidate portion, and an inspection region generation unit includes the first defect candidate portion. An inspection region is generated so as to be included, and a second extraction unit binarizes the inspection region with a second threshold value that is smaller than the first threshold value, and extracts a second defect candidate portion; The defect candidate portion is a region in which the second defect candidate portion is expanded.

  Further, the inspection area is an area surrounded by a rectangle enlarged by a predetermined width from a minimum rectangle including the first defect candidate portion.

  Further, the expansion process is a process of expanding the second defect candidate portion in at least the major axis direction.

  The flaw detection apparatus is a magnetic particle flaw detection apparatus further comprising a magnetic powder spraying device that applies magnetic powder to the inspection object, and a magnetization device that magnetizes the inspection object to form a magnetic particle instruction pattern by a leakage magnetic flux. And

  Furthermore, the length of the width calculation region is 0.3 mm or more and 10 mm or less.

  According to the present disclosure, in the flaw detection apparatus including an input device that images an inspection object and a detection device that detects a defect of the inspection object from an original image acquired by the input device, the detection device is extracted from the original image. In the width calculation region having a predetermined length in the major axis direction of the defect candidate portion, the defect candidate portion fits between two straight lines parallel to the major axis direction of the defect candidate portion, and between the two straight lines When the distance (width) is within a predetermined range, the defect determination unit determines that the defect candidate portion is a defect, so that the shape of the defect of the inspection object is quantitatively extracted as a feature amount, and the defect And other than that can be identified with high accuracy, and overdetection can be reduced. Therefore, it is possible to provide a flaw detection apparatus with an increased defect detection rate.

  Furthermore, the width calculation area includes the center of gravity of the defect candidate portion, so that the shape of the defect of the inspection object can be more quantitatively extracted as a feature amount, and the defect and the other can be identified with higher accuracy. Detection omission and overdetection can be further reduced. Therefore, it is possible to provide a flaw detection apparatus with a higher defect detection rate.

  A detection apparatus binarizes an original image with a first threshold value to extract a first defect candidate portion, and an inspection region that generates an inspection region so as to include the first defect candidate portion A generation unit; and a second extraction unit that binarizes the inspection region with a second threshold value that is smaller than the first threshold value and extracts a second defect candidate unit. Since the second defect candidate portion is a region subjected to the expansion process, the defect shape of the inspection object is prevented from being overdetected and overdetected, and the shape of the defect is more reliably extracted as the feature quantity more reliably. , Defects can be identified with higher accuracy, and overdetection can be further reduced. Therefore, it is possible to provide a flaw detection apparatus with a higher defect detection rate.

  Furthermore, the inspection area is an area surrounded by a rectangle that is enlarged by a predetermined width from the smallest rectangle including the first defect candidate portion, so that a defect in the inspection object is not detected and overdetected. Thus, the shape of the defect can be more reliably quantitatively extracted as the feature quantity, and the defect and the other can be identified with higher accuracy to further reduce overdetection. Therefore, it is possible to provide a flaw detection apparatus with a higher defect detection rate.

  Furthermore, the expansion process is a process of expanding the second defect candidate portions in at least the major axis direction, thereby preventing defects in detection of defects of the inspection object and overdetection more reliably. Thus, the shape is more quantitatively extracted as the feature amount, and the defect and the other can be identified with higher accuracy to further reduce the overdetection. Therefore, it is possible to provide a flaw detection apparatus with a higher defect detection rate.

  The flaw detection device is a magnetic particle flaw detection device further comprising a magnetic powder spraying device that applies magnetic powder to an object to be inspected and a magnetizing device that magnetizes the object to be inspected to form a magnetic powder instruction pattern by a leakage magnetic flux. The shape of the defect of the object to be inspected can be more reliably quantitatively extracted as the feature quantity, and the defect and the other can be identified with higher accuracy to further reduce overdetection. Therefore, it is possible to provide a flaw detection apparatus with a higher defect detection rate.

  Furthermore, since the length of the width calculation region is 0.3 mm or more and 10 mm or less, the shape of the defect of the inspection object can be more quantitatively extracted as the feature amount more reliably, Can be identified with higher accuracy, and detection omission and overdetection can be further reduced. Therefore, it is possible to provide a flaw detection apparatus with a higher defect detection rate.

  Furthermore, the present disclosure provides a defect detection method using a flaw detection device in which an input device photographs an object to be inspected, and a detection device detects a defect of the object to be inspected from an original image acquired by the input device. In the width calculation region having a predetermined length in the major axis direction of the defect candidate portion extracted from the original image, the defect determination unit has a defect candidate between two straight lines parallel to the major axis direction of the defect candidate portion. Since the defect candidate portion is determined as a defect when the portion is within the range and the distance (width) between the two straight lines is within a predetermined range, the shape of the defect of the inspection object is quantitatively determined as a feature amount. It is possible to identify the defect and the other with high accuracy and reduce overdetection. Therefore, it is possible to provide a defect detection method using a flaw detector with an increased defect detection rate.

  Furthermore, the width calculation area includes the center of gravity of the defect candidate portion, so that the shape of the defect of the inspection object can be more quantitatively extracted as a feature amount, and the defect and the other can be identified with higher accuracy. Detection omission and overdetection can be further reduced. Therefore, it is possible to provide a defect detection method using a flaw detection apparatus with a higher defect detection rate.

  The first extraction unit further included in the detection device binarizes the original image with the first threshold to extract the first defect candidate portion, and the inspection region generation unit includes the first defect candidate portion. The second extraction unit binarizes the inspection region with a second threshold value that is smaller than the first threshold value, and extracts a second defect candidate portion. Since the second defect candidate portion is a region subjected to the expansion process, the defect shape of the inspection object is prevented from being overdetected and overdetected, and the shape of the defect is more reliably extracted as the feature quantity more reliably. , Defects can be identified with higher accuracy, and overdetection can be further reduced. Therefore, it is possible to provide a defect detection method using a flaw detection apparatus with a higher defect detection rate.

  Furthermore, the inspection area is an area surrounded by a rectangle that is enlarged by a predetermined width from the smallest rectangle including the first defect candidate portion, so that a defect in the inspection object is not detected and overdetected. Thus, the shape of the defect can be more reliably quantitatively extracted as the feature quantity, and the defect and the other can be identified with higher accuracy to further reduce overdetection. Therefore, it is possible to provide a defect detection method using a flaw detection apparatus with a higher defect detection rate.

  Furthermore, the expansion process is a process of expanding the second defect candidate portions in at least the major axis direction, thereby preventing defects in detection of defects of the inspection object and overdetection more reliably. Thus, the shape is more quantitatively extracted as the feature amount, and the defect and the other can be identified with higher accuracy to further reduce the overdetection. Therefore, it is possible to provide a defect detection method using a flaw detection apparatus with a higher defect detection rate.

  The flaw detection device is a magnetic particle flaw detection device further comprising a magnetic powder spraying device that applies magnetic powder to an object to be inspected and a magnetizing device that magnetizes the object to be inspected to form a magnetic powder instruction pattern by a leakage magnetic flux. The shape of the defect of the object to be inspected can be more reliably quantitatively extracted as the feature quantity, and the defect and the other can be identified with higher accuracy to further reduce overdetection. Therefore, it is possible to provide a defect detection method using a flaw detection apparatus with a higher defect detection rate.

  Furthermore, since the length of the width calculation region is 0.3 mm or more and 10 mm or less, the shape of the defect of the inspection object can be more quantitatively extracted as the feature amount more reliably, Can be identified with higher accuracy, and detection omission and overdetection can be further reduced. Therefore, it is possible to provide a defect detection method using a flaw detection apparatus with a higher defect detection rate.

It is the schematic diagram by which the magnetic particle flaw detector as an example of the flaw detector concerning this embodiment was shown. It is the block diagram in which an example of the control system of a magnetic particle testing apparatus was shown. It is a flowchart for demonstrating an example of the detection operation of a detection apparatus. It is the schematic by which an example of the image binarized by the 1st extraction part was shown. It is the schematic of the image by which the extracted 1st defect candidate part and an example of the produced | generated test | inspection area | region were shown. It is the schematic by which an example of the image binarized by the 2nd extraction part was shown. It is the schematic of the image in which an example of the extracted 2nd defect candidate part was shown. It is the schematic of the image by which the example by which the 2nd defect candidate part was expanded is shown. It is the schematic for demonstrating an example of the method of extracting the feature-value of a defect candidate part. It is the schematic of the image in which an example of the extracted defect was shown.

  The details of the embodiments of the present disclosure will be described below with reference to the drawings. First, the flaw detection apparatus according to the present embodiment will be described in detail. FIG. 1 is a schematic diagram showing a magnetic particle flaw detector 1 as an example of a flaw detector according to the present embodiment. In addition, the conveyance direction of the to-be-inspected object 10 which is an inspection object of the magnetic particle flaw detector 1 is set from right to left as indicated by an arrow in FIG.

  The magnetic particle flaw detection apparatus 1 is an apparatus that automatically detects a surface of the inspection object 10 having ferromagnetism or a defect immediately below the surface using magnetic powder as a marker. A magnetic particle flaw detector 1 illustrated in FIG. 1 is used for an inspection object having a relatively large size, and the inspection object 10 is a long prismatic steel material. The magnetic particle inspection device 1 includes a roller conveyor 11, a magnetic particle dispersion device 12, a magnetizing device 13, an air blow device 14, an ultraviolet flaw detection lamp 15, a camera 16, and a marking device 17. Further, the magnetic particle flaw detector 1 includes a controller (not shown), a detection device, and the like.

  A roller conveyor 11 as a conveying device conveys the inspection object 10. The roller conveyor 11 includes a plurality of rollers and is configured to convey the inspection object 10 at a desired speed. Then, the roller conveyor 11 conveys the inspection object 10 from the position of the magnetic particle spraying device 12 to the position of the marking device 17 through the position where the magnetizing device 13, the ultraviolet flaw detection lamp 15, the camera 16, etc. are provided. Provided in the route. The conveying device is not limited to the roller conveyor 11 as long as the object to be inspected 10 can be conveyed, and may be, for example, a belt conveyor constituted by an endless belt or the like.

  The roller conveyor 11 is provided with a transport distance measuring device (not shown). The transport distance measuring device measures the transport distance of the inspection object 10. As the transport distance measuring device, for example, a device in which a rotary encoder that measures the rotational displacement of the rollers of the roller conveyor 11 is used as a sensor can be used. The transport distance measuring device is not limited to a rotary encoder, and a non-contact measuring device such as a laser surface velocimeter may be used, or a combination of these may be used.

  The magnetic powder spraying device 12 applies (spreads) magnetic powder as a label to the surface of the inspection object 10 to be inspected, and is arranged on the upstream side in the transport direction of the inspection object 10. As the magnetic powder, for example, fluorescent magnetic powder in which the surface of magnetic powder (iron powder) is coated with a phosphor is used, and a magnetic powder inspection liquid in which the fluorescent magnetic powder is dispersed in water or oil is used. The magnetic powder spraying device 12 includes, for example, a tank, a pump, a nozzle, and the like (not shown), and is configured to pump the magnetic powder inspection liquid stored in the tank with a pump and to eject the liquid from the nozzle. The magnetic powder spraying device 12 is configured so that a desired amount of magnetic powder test liquid can be continuously sprayed on the surface of the inspection object 10.

  The magnetizing device 13 applies a magnetic field to the object 10 to be magnetized, and is arranged adjacent to the downstream side of the magnetic particle spraying device 12. The magnetizing device 13 is arranged in a row in the transport direction between the two penetration coils 19 and 20 that are disposed to face the upstream side and the downstream side in the transport direction of the inspection object 10. Two inter-pole coils 21 and 22. The through coils 19 and 20 are formed in an annular shape, and the conveyance path of the inspection object 10 is arranged so as to penetrate the annular ring. On the other hand, the interpolar coils 21 and 22 are formed in a U shape, and the conveyance path of the inspection object 10 is arranged so as to pass through the gap. The magnetizing device 13 is configured to generate a uniform rotating magnetic field between the two penetration coils 19 and 20 by including the two inter-pole coils 21 and 22.

  More specifically, the through coils 19 and 20 generate a magnetic field in the conveyance direction of the inspection object 10, and the interpolar coils 21 and 22 generate a magnetic field in a direction perpendicular to the conveyance direction of the inspection object 10 that is the gap direction. Is generated. Then, when an alternating current having a phase difference of 90 degrees flows through the through coils 19 and 20 and the interpolar coils 21 and 22, the plane formed by the magnetic field in the transport direction and the magnetic field in the direction orthogonal to the transport direction A rotating magnetic field that rotates at a constant magnetic field strength is generated. By this rotating magnetic field, a leakage magnetic flux is generated on the surface layer portion of the object to be inspected regardless of the direction of the flaw, and a magnetic powder indicating pattern is formed.

  The number of penetrating coils 19 and 20 constituting the magnetizing device 13 and the number of inter-pole coils 21 and 22 are appropriately designed. For example, the magnetizing device 13 may be configured to further include a plurality of inter-pole coils in addition to the inter-pole coils 21 and 22, while being configured by one through coil 19 and one inter-pole coil 21. It may be.

  The air blowing device 14 blows air toward the object 10 in a direction against gravity, and has a function of adjusting the flow rate of the magnetic particle inspection liquid flowing on the surface of the object 10. And the magnetic powder instruction | indication pattern formed with this air blow apparatus 14 becomes clear. The air blow device 14 is provided between the penetration coil 19 and the interpolar coil 21, between the two interpolar coils 21 and 22, and between the interpolar coil 22 and the penetration coil 20.

  The ultraviolet flaw detection lamp 15 as a light source irradiates the magnetic particle inspection liquid on the surface of the inspection object 10 between the two penetration coils 19 and 20 with ultraviolet rays. In order to make the ultraviolet intensity in the photographing range of the camera 16 uniform, the ultraviolet flaw detection lamp 15 is preferably provided with a parabolic reflector. In order to avoid the influence of a strong rotating magnetic field generated by the magnetizing device 13, the ultraviolet flaw detection lamp 15 is preferably arranged so as to be separated from the inspection object 10 by an appropriate distance, for example, about 600 mm to 2000 mm. The ultraviolet flaw detection lamp 15 may be magnetically shielded.

  For example, when non-fluorescent magnetic powder in which the surface of magnetic powder (iron powder) is coated with a color pigment such as white, black, and red is used as the magnetic powder, the light source may be visible light. However, when ultraviolet light is irradiated to the fluorescent magnetic powder, the magnetic powder indicating pattern shines brightly (emits light) in the visible light region, and is not easily affected by dirt on the surface of the object 10 to be inspected, scale, etc. It is possible to detect failure of accuracy. For this reason, it is more preferable to use the ultraviolet flaw detection lamp 15 and the fluorescent magnetic powder.

  The camera 16 serving as an input device photographs the surface of the inspection object 10 irradiated with ultraviolet rays by the ultraviolet flaw detection lamp 15. The camera 16 is preferably arranged to take an image from a direction perpendicular to the surface of the inspection object 10 in order to detect a defect with higher accuracy. Further, the camera 16 is arranged at an appropriate distance from the object 10 to be inspected, for example, about 600 mm to 2000 mm, and is magnetically shielded in order to avoid the influence of the strong rotating magnetic field generated by the magnetizing device 13. It is preferable.

  As the camera 16, a line camera or an area camera may be used. Further, for the elements mounted on the camera 16, a CCD (Charge Coupled Device) image sensor may be used, or a CMOS (Complementary Metal-Oxide Semiconductor) image sensor may be used.

  The marking device 17 performs visible marking on the surface defect of the inspection object 10 detected by the detection device. As the marking device 17, for example, a marking gun that performs marking by ejecting ink with air pressure can be used. Note that the marking device 17 may be omitted when the magnetic particle flaw detector 1 is used for an inspection object having a relatively small size, for example, when a defective product can be discharged to a defective product pallet together with the product.

  Next, the control system of the magnetic particle flaw detector 1 according to this embodiment will be described in detail. FIG. 2 is a block diagram illustrating an example of a control system of the magnetic particle inspection device 1.

  The magnetic particle inspection apparatus 1 includes a controller C. The controller C includes a roller conveyor 11, a transport distance measuring device 18, a magnetic powder spreading device 12, a magnetizing device 13, an air blowing device 14, an ultraviolet flaw detection lamp 15, a camera 16, a marking device 17, and a detection The device 30 is electrically connected. Various sensors other than the configuration illustrated in FIG. 2 are also electrically connected to the controller C. The magnetic particle inspection apparatus 1 is configured such that the controller C automatically detects defects on the surface of the inspection object 10 by controlling the above-described various apparatuses.

  The controller C is configured to control operations of various devices included in the magnetic particle flaw detector 1 by reading input signals such as various setting values and detection values by various sensors and outputting a control signal. . The controller C includes a processing device that performs arithmetic processing and control processing, a main storage device that stores data, and the like. The controller C includes, for example, a CPU (Central Processing Unit) as a processing device, a ROM (Read Only Memory) or RAM (Random Access Memory) as a main storage device, a timer, an input circuit, an output circuit, a power supply circuit, and the like. It is a computer. The main storage device stores a control program for executing operations according to the present embodiment, various data, and the like. The various programs, data, and the like may be stored in a storage device provided separately from the controller C and read by the controller C.

  The detection device 30 detects an image surface defect of the inspection object 10 by reading an image signal (original image) acquired by the camera 16 and performing a predetermined process on the original image. The controller C is configured to input the original image acquired by the camera 16 to the detection device 30. Like the controller C, the detection device 30 includes a processing device that performs arithmetic processing and control processing, a main storage device that stores data, and the like. For example, a CPU, a main storage device, a timer, an input circuit, and an output circuit The microcomputer includes a power supply circuit and the like.

  The detection device 30 includes at least a defect determination unit that determines whether the defect candidate portion extracted from the original image is a defect. Thereby, the shape of the defect of the inspection object 10 is quantitatively extracted as a feature amount, and it is possible to identify the defect and the other with high accuracy and reduce overdetection. Therefore, it is possible to provide a flaw detection apparatus with an increased defect detection rate.

  The detection device 30 illustrated in FIG. 2 includes a first extraction unit 31, an inspection region generation unit 32, a second extraction unit 33, and a defect determination unit 34. Each of these units is configured by a program, for example. Note that the function of each unit may be configured to be realized by hardware.

  The first extraction unit 31 is configured to input an original image acquired by the camera 16 and binarize with a predetermined first threshold to extract a first defect candidate portion.

  The inspection region generation unit 32 is configured to generate an inspection region so that the first defect candidate portion extracted by the first extraction unit 31 is included.

  The second extraction unit 33 is configured to input the inspection region generated by the inspection region generation unit 32, binarize with a predetermined second threshold value, and extract the second defect candidate portion. Yes.

  The defect determination unit 34 is configured to input the second defect candidate portion extracted by the second extraction unit 33, calculate the width of the expanded defect candidate portion, and detect the defect. The detection device 30 is configured to output the position data of the defect detected by the defect determination unit 34 to the controller C.

  Next, the operation of the magnetic particle flaw detector 1 will be described in detail. The magnetic particle inspection apparatus 1 is configured such that the inspection object 10 is sequentially conveyed to each apparatus by a roller conveyor 11 and a surface defect of the inspection object 10 is detected.

  First, a magnetic particle inspection liquid is applied to the surface of the inspection object 10 by the magnetic particle spraying device 12. The inspection object 10 to which the magnetic particle inspection liquid is applied on the surface is conveyed into a rotating magnetic field region formed by the magnetizing device 13. At that time, if there is a flaw on the surface of the object to be inspected 10, a leakage magnetic field caused by the flaw is generated, and the magnetic powder contained in the magnetic particle inspection liquid is attracted to the leakage magnetic field. At this time, since the magnetic field formed by the magnetizing device 13 is rotating, a leakage magnetic field is generated regardless of the extending direction or shape of the flaw, and the magnetic powder is attracted to any flaw. Then, the magnetic powder gathers without flaws, so that a magnetic powder indication pattern corresponding to the flaws is formed on the surface of the inspection object 10.

  The flow rate of the magnetic particle inspection liquid flowing on the surface of the inspection object 10 is appropriately adjusted by the air blow device 14. If the flow rate of the magnetic particle inspection liquid is too low, a long time is required until the magnetic particle indicating pattern is formed and stabilized, and the inspection efficiency is lowered. On the other hand, if the flow rate of the magnetic particle inspection liquid is too high, the magnetic particles are less likely to be attracted to the leakage magnetic field caused by the flaws, and the magnetic particle indicating pattern becomes uncertain. Therefore, the flow rate of the magnetic particle inspection liquid is preferably 5 mm / s or more and 100 mm / s or less from the viewpoint of reliably forming the magnetic particle instruction pattern.

  The magnetic powder indicating pattern thus formed is emitted when the phosphor covering the surface of the magnetic powder absorbs and excites the ultraviolet energy irradiated by the ultraviolet flaw detection lamp 15 and returns to the ground state. The high-luminance visible light is captured by the camera 16. The original image acquired by the camera 16 is input to the detection device 30. The detection device 30 performs a predetermined process on the original image to detect a defect in the original image, and outputs the position data to the controller C. The controller C controls the operation of the marking device 17 based on the defect position data and the measurement data of the transport distance measuring device 18. A marking device 17 marks the surface defect of the inspection object 10.

  Next, the defect detection method by the detection device 30 will be described in detail. In the defect detection method using the flaw detection apparatus according to the present embodiment, first, the defect determination unit 34 included in the detection apparatus 30 has a width having a predetermined length in the major axis direction of the defect candidate part extracted from the original image. Cut out the calculation area. Then, the defect determination unit 34 includes a range in which the defect candidate portion is accommodated between two straight lines parallel to the major axis direction of the defect candidate portion and the distance (width) between the two straight lines is predetermined in the width calculation region. If it is within the range, the defect candidate portion is determined as a defect. As described above, in the defect detection method using the flaw detection apparatus according to the present embodiment, the defect shape of the inspection object 10 is quantitatively extracted as the feature amount by inputting the defect candidate portion, Can be identified with high accuracy to reduce overdetection. Therefore, it is possible to provide a defect detection method using a flaw detector with an increased defect detection rate.

  In the defect detection method using the flaw detection apparatus according to the present embodiment, a step of extracting a defect candidate portion can be included so as to more reliably prevent detection of defects of the inspection object 10 and overdetection. Next, a defect detection method using such a flaw detector will be described in detail. FIG. 3 is a flowchart for explaining an example of the detection operation of the detection device 30.

  First, the detection device 30 captures an image (step S1). The detection device 30 captures an image signal (original image) acquired by the camera 16 via the controller C. The original image is composed of pixels of horizontal × vertical, for example, 1280 × 960. The original image stores shooting time information.

  In the defect detection method using the flaw detection apparatus according to the present embodiment, a defect is extracted from an original image through roughly three steps. The first step (i) is performed by the first extraction unit 31.

  First, the first extraction unit 31 performs enhancement processing (step S2). The first extraction unit 31 performs enhancement processing on the original image using various filters as preprocessing. The enhancement process may be any process in which flaws in the original image are enhanced. For example, LUT (Look Up Table) conversion process, enlargement / shrinkage process, shading process, and the like are combined. There may be. Although it is possible to omit the enhancement process, it is preferable to perform the enhancement process in order to increase the defect detection rate.

  Next, the 1st extraction part 31 binarizes with a 1st threshold value (step S3). The first extraction unit 31 binarizes the enhanced image (original image when the enhanced processing is omitted) with a first threshold value. The first threshold value is set in advance as an appropriate value adjusted to detect a defect with high accuracy, and is stored in a main storage device (not shown) of the detection device 30. The detection device 30 may be configured to change the first threshold value.

  FIG. 4 is a schematic diagram illustrating an example of an image binarized by the first extraction unit 31. Note that FIG. 4 shows pixels extracted for the description. In FIG. 4, the magnetic powder instruction pattern is shown in black. Labeling is performed for each magnetic powder indicating pattern displayed in black. Here, labeling is a process of assigning the same label (number) to pixels connected in a binarized image, that is, a region closed by one contour line, and dividing the region.

  And the 1st extraction part 31 extracts the area | region applicable to a 1st defect candidate part (step S4). This is the first step. The first extraction unit 31 calculates, for example, an area, a length, a vertical width, and a horizontal width as determination values for each labeled region. And the 1st extraction part 31 compares these calculated judgment values with the 1st judgment standard value stored beforehand, and judges whether it is the 1st defect candidate part, A region corresponding to the first defect candidate portion is extracted.

  Here, the first defect candidate portion is a region assumed to be a defect. And the 1st extraction part 31 determines whether it is a 1st defect candidate part similarly about all the area | regions to which the label was attached | subjected.

  FIG. 5 is a schematic diagram of an image showing an example of the extracted first defect candidate portion 40 and the generated inspection area 41. FIG. 5 shows a state in which the first defect candidate portion 40 is extracted using the length of the region as a determination value, and the eight first defect candidate portions 40a, 40b, 40c, 40d, 40e, 40f, and 40g. , And 40h are extracted.

  The determination value may be set as appropriate as long as it can compare the characteristics of the regions. Furthermore, the determination as to whether or not the defect candidate portion 40 is the first defect candidate 40 may be performed based on one type of determination value, or may be performed based on a plurality of types of determination values. Furthermore, when it is determined based on a plurality of types of determination values whether or not it is the first defect candidate portion 40, a determination is made based on at least one type of determination values among the plurality of types of determination values. If it is made. For example, a method of determining that the region is the first defect candidate portion 40 when at least two of the three determination values satisfy the criterion may be used.

  Further, the first extraction unit 31 does not repeat step S4 for each area, but first calculates the determination values for all areas, and then calculates the calculated determination value and the first determination reference value for each area. And whether or not it is the first defect candidate portion 40 may be determined.

  Next, the process proceeds to the second step (ii). The second step is performed by the inspection region generation unit 32 and the second extraction unit 33 of the detection device 30.

  The inspection area generation unit 32 generates an inspection area 41 (step S5). The inspection region generation unit 32 generates the inspection region 41 so that each of the first defect candidate portions 40 extracted by the first extraction unit 31 is included. As described above, the inspection area 41 is narrowed to the vicinity of the first defect candidate portion 40, thereby preventing overdetection in which flaws, dust and the like that are not harmful are detected as defects in an area where there is a low possibility that a defect exists. The Furthermore, the calculation amount of the detection device 30 is reduced.

  FIG. 5 shows inspection regions 41a, 41b, 41c, 41d, 41e, and 41f generated corresponding to the eight first defect candidate portions 40a, 40b, 40c, 40d, 40e, 40f, 40g, and 40h, respectively. , 41g, and 41h. The inspection area 41 illustrated in FIG. 5 is an area surrounded by a rectangle extending in the vertical direction and the horizontal direction. The inspection area 41 is an area surrounded by a rectangle which is enlarged by a predetermined width in the vertical direction and the horizontal direction from the smallest area.

  The vertical and horizontal enlargement widths may be the same or different. Here, the inspection area 41 may be an area including the first defect candidate portion 40, and may be an area surrounded by a rhombus, a trapezoid, a circle, an ellipse, or the like. Further, the inspection area 41 may be an inclined area, and may be, for example, a rectangle that extends in the major axis direction of the first defect candidate portion 40.

  Next, the second extraction unit 33 performs enhancement processing (step S6). The second extraction unit 33 performs enhancement processing on the inspection area 41 of the original image in the same manner as step S <b> 2 by the first extraction unit 31. The detection device 30 stores the image enhanced in step S2 in the main storage unit, and the second extraction unit 33 cuts out the inspection region 41 of the stored image so that step S6 is omitted. May be made. By using such a method, the calculation amount of the detection device 30 can be reduced.

  Further, the second extraction unit 33 performs binarization with the second threshold (step S7). The second extraction unit 33 binarizes the enhanced image (or the original image when the enhancement process is omitted) with a second threshold value that is smaller than the first threshold value. The second threshold value is set in advance as an appropriate value adjusted to detect a defect with high accuracy, and is stored in a main storage device (not shown) of the detection device 30. The detection device 30 may be configured to change the second threshold value.

  FIG. 6 is a schematic diagram illustrating an example of an image binarized by the second extraction unit 33. Here, referring to FIG. 6, many smaller regions are extracted as compared to FIG. 4. For example, the regions corresponding to the first defect candidate portion 40c and the first defect candidate portion 40d in FIG. 5 are connected and formed as one region. This is because the second threshold value is smaller than the first threshold value, and the region where the width of the flaw is narrow or shallow and the magnetic powder indicating pattern is not clear and the luminance is lower is also detected. Because.

  A flaw is photographed in a state where a region with high luminance and a region with low luminance are present randomly according to the depth and width of a single continuous image. However, by binarizing with the second threshold value that is smaller than the first threshold value, it is possible to detect a region with lower luminance, and the region corresponding to the defect is not interrupted at a shallow portion or the like. Can be. Then, as with the first extraction unit 31, the second extraction unit 33 labels the individual magnetic powder instruction patterns of the binarized image.

  And the 2nd extraction part 33 extracts the area | region applicable to a 2nd defect candidate part (step S8). This is the second step. The second extraction unit 33 calculates, for example, an area, a length, a vertical width, and a horizontal width as determination values for each labeled region. Then, the second extraction unit 33 compares these calculated determination values with a second determination reference value stored in advance to determine whether or not it is a second defect candidate portion, A region corresponding to the second defect candidate portion is extracted.

  Here, the second defect candidate portion is a region assumed to be a defect, like the first defect candidate portion. And the 2nd extraction part 33 determines whether it is a 2nd defect candidate part similarly about all the area | regions to which the label was attached | subjected.

  The second determination reference value is a value that makes the region less likely to be extracted as a defect than the first determination reference value used in the first extraction unit 31. The phrase “not easily extracted” means that, for example, a defect cannot be extracted unless it is a larger area or a longer area. That is, the range of the second determination reference value is included in the range of the first determination reference value and is a narrow range.

  FIG. 7 is a schematic diagram of an image showing an example of the extracted second defect candidate part 42. FIG. 7 shows a state in which the second defect candidate part 42 is extracted using the length of the region as a determination value. The six second defect candidate parts 42a, 42b, 42c, 42e, 42f, and 42g It is an extracted state. In FIG. 7, a region corresponding to the first defect candidate portion 40h in FIG. 5 is not extracted. This is because the second determination reference value is a value that is less likely to be extracted as a defect than the first determination reference value, and therefore the region corresponding to the first defect candidate portion 40h is assumed to be a defect. This is because it is determined not to be an area.

  The determination value may be set as appropriate as long as it can compare the characteristics of the regions. Furthermore, the determination as to whether or not it is the second defect candidate portion 42 may be performed based on one type of determination value, or may be performed based on a plurality of types of determination values. Further, when it is determined based on a plurality of types of determination values whether or not it is the second defect candidate portion 42, the determination is made based on at least one type of determination values among the plurality of types of determination values. If it is made. For example, a method of determining that the region is the second defect candidate portion 42 when at least two of the three determination values satisfy the criterion may be used.

  It should be noted that the second determination reference value may not be a value at which a region is more likely to be extracted as a defect than the first determination reference value. For example, the second determination reference value may be the same as the first determination reference value. In such a case, the second extraction unit 33 has more types than the first extraction unit 31. Based on the determination value, it is configured to determine whether or not it is the second defect candidate portion 42.

  Further, as with the first extraction unit 31, the second extraction unit 33 does not repeat step S8 for each region, but instead calculates the determination values for all regions before calculating each region. A comparison between the determined determination value and the second determination reference value and determination of whether or not the second defect candidate portion 42 is made may be performed.

  Next, the process proceeds to the third step (iii). The third step is performed by the defect determination unit 34 of the detection device 30.

  The defect determining unit 34 performs an expansion process on each of the second defect candidate units 42 (step S9). Here, the expansion process is a process for expanding (expanding) the region of the second defect candidate portion 42. The defect determination unit 34 enlarges each of the second defect candidate units 42 by a predetermined amount in the vertical direction and the horizontal direction. That is, the expansion process of the defect determination unit 34 is a process of expanding the second defect candidate unit 42 in the outer circumferential direction. At that time, the expansion process may be performed at least in the major axis direction of each of the second defect candidate portions 42. By this expansion processing, it is prevented that one continuous flaw is discontinuous and it is determined that it is not a defect, and defect detection omission is prevented. In this manner, the expanded region of the second defect candidate portion 42 is set as a defect candidate portion.

  FIG. 8 is a schematic diagram of an image showing an example in which the second defect candidate portion 42 is expanded. Referring to FIG. 8, for example, the three second defect candidate portions 42a, 42b, and 42c in FIG. 7 are connected by expansion processing to form one defect candidate portion 43a. And the defect determination part 34 is the same as the 1st extraction part 31 and the 2nd extraction part 33 about the individual defect candidate part 43 formed by the 2nd defect candidate part 42 being expanded. Perform labeling.

  Next, the defect determination unit 34 regards the defect candidate unit 43 as an elliptical arc and approximates it with an ellipse, and calculates the center of gravity and the major axis of the defect candidate unit 43 based on the ellipse (step S10). FIG. 9 is a schematic diagram for explaining an example of a method for extracting the feature amount of the defect candidate portion 43a. FIG. 9 shows the center of gravity c (centroid) calculated at a position inside the defect candidate portion 43a that curves in an elliptical arc shape.

  Next, the width calculation area Lc is cut out (step S11). The defect determination unit 34 cuts out a width calculation region Lc having a predetermined length in the major axis direction of the defect candidate unit 43a. The width calculation region Lc is a value determined in advance according to the processing stage, processing method, and the like of the inspection object 10.

  Note that if the width calculation region Lc is too small, there is a high possibility that a non-defect will show a feature as a defect, and the false detection rate will increase. On the other hand, if the width calculation region Lc is too large, it is difficult to extract features as the defect candidate portion 43a because the width B of the defect candidate portion 43a as a whole is calculated instead of the line width of the defect candidate portion 43a. As a result, the rate of defect detection omission increases. For this reason, the length of the width calculation region Lc is preferably 0.3 mm or more and 10 mm or less, and more preferably 1 mm or more and 6 mm or less. By setting the width calculation region Lc in such a range, the shape of the defect of the inspection object 10 is more reliably extracted quantitatively as the feature amount, and the defect and the other are identified with higher accuracy. Detection omission and overdetection can be further reduced.

  Any defect, a magnetic discontinuity that does not become a defect, a surface shape change part, or the like is not easily distinguished in the vicinity of the end. Furthermore, as the distance from the vicinity of the center of gravity increases, the inclination with respect to the major axis direction increases and it becomes difficult to detect an accurate line width. Accordingly, the width calculation region Lc preferably includes the center of gravity c of the defect candidate portion 43a. Thereby, the shape of the defect of the inspection object 10 is more reliably extracted quantitatively as the feature amount, and it is possible to identify the defect and the other with higher accuracy and further reduce overdetection. Here, that the width calculation region Lc includes the center of gravity c of the defect candidate portion 43a means that when a line is extended from each of both ends of the width calculation region Lc in a direction perpendicular to the major axis direction, between the two lines. This means that the center of gravity c is located.

  Next, the defect determination unit 34 calculates the width w (step S12). The width w is such that the defect candidate portion 43a fits between two straight lines parallel to the major axis direction of the defect candidate portion 43, and the distance between the two straight lines is minimized.

  First, the defect determination unit 34 draws two straight lines s1 and s2 parallel to the major axis direction of the defect candidate portion 43a on both outer sides with the defect candidate portion 43a interposed therebetween. In the illustration of FIG. 9, a straight line s1 is drawn on the inner side where the defect candidate portion 43a is curved, and a straight line s2 is drawn on the outer side. Further, the defect determining unit 34 brings the two straight lines s1 and s2 closer to the defect candidate unit 43a while keeping parallel to the major axis direction. That is, the straight line s1 is approximated in the direction indicated by the arrow d1, and the straight line s2 is approximated in the direction indicated by the arrow d2. Then, a position where each of the straight line s1 and the straight line s2 first intersects with the outline of the defect candidate portion 43a, that is, an intersection point v1 and an intersection point v2 is determined. The distance between the two straight lines s1 and s2 determined in this way is defined as the width w of the defect candidate portion 43a.

  When the width w is within a predetermined range, the defect determination unit 34 detects the defect by determining the defect candidate unit 43a as a defect (step S13). The defect detection is performed in the same manner for the defect candidate portions 43e and 43f shown in FIG.

  FIG. 10 is a schematic diagram of an image showing an example of the extracted defect 50. Of the three defect candidate portions 43a, 43e, and 43f in FIG. 9, the defect candidate portions 43e and 43f are excluded, and only the defect candidate portion 43a is determined as the defect 50. Then, the detection device 30 outputs position data of the detected defect 50 to the controller C.

  The magnetic powder indicating pattern formed on the object to be inspected 10 is characterized by its formation factor. For example, the magnetic particle indicating pattern of harmful flaws has the characteristics that the outline is clear, line shape, and there are few discontinuities, while the magnetic powder indicating pattern of harmless flaws has the outline, unknown, serrated, and many discontinuities, etc. It has the following characteristics. Such a feature of the magnetic particle indicating pattern is particularly prominent in the width w when image processing is performed in the magnetic particle inspection test. In the present embodiment, the value of the width w is reflected in the determination criterion, so that the magnetic powder instruction pattern due to harmful flaws is distinguished from other magnetic powder instruction patterns. Therefore, according to the defect detection method by the magnetic particle flaw detector 1 according to the present embodiment, it is possible to grasp the characteristics of the new magnetic particle instruction pattern shape as a value in image processing, and the magnetic particle instruction pattern due to harmful flaws and the others It is possible to identify the magnetic powder instruction pattern with higher accuracy.

  The determination as to whether or not the defect candidate portion 43 is the defect 50 may be made based on other determination values in addition to the width w. In that case, as in step S4, for example, the area, length, vertical width, and horizontal width are used as determination values, and whether or not the defect is based on a comparison with a defect determination reference value. May be used. At that time, the determination based on the width w may be prioritized. The defect determination reference value may be a value that makes the region less likely to be extracted as a defect than the second determination reference value in the second extraction unit 33.

  Note that the detection device 30 may be configured such that data such as an original image, an image extracted in each step, a calculated width w, a determination value, and the like are appropriately stored in the main storage unit.

  Furthermore, the detection device 30 may be configured to be able to appropriately change values such as each threshold value, each determination reference value, and a width calculation region. Thereby, the size of the defect detected as a defect can be changed as appropriate, the inspection accuracy of the defect can be adjusted as appropriate, and it is easy to use.

  As described above, in the present embodiment, the camera 16 images the inspection object 10, and the detection apparatus 30 detects the defect of the inspection object 10 from the original image acquired by the camera 16. In the defect detection method, the defect determination unit 34 included in the detection device 30 has the defect candidate unit 43 in the width calculation region Lc having a predetermined length in the major axis direction of the defect candidate unit 43 extracted from the original image. When the defect candidate portion 43 is accommodated between two straight lines s1 and s2 parallel to the major axis direction of and the width w at which the distance between the two straight lines s1 and s2 is minimum is within a predetermined range, The defect candidate part 43 is determined as the defect 50.

  Thereby, the shape of the defect of the inspection object 10 is quantitatively extracted as a feature amount, and it is possible to identify the defect and the other with high accuracy and reduce overdetection. Therefore, according to the present embodiment, it is possible to provide a defect detection method using the magnetic particle flaw detector 1 with an increased defect detection rate.

  Furthermore, the magnetic particle flaw detector 1 according to the present embodiment includes a camera 16 that images the inspection object 10 and a detection device 30 that detects a defect of the inspection object 10 from an original image acquired by the camera 16. In the width calculation region Lc having a predetermined length in the major axis direction of the defect candidate portion 43 extracted from the original image, the apparatus 30 has two straight lines s1 and s2 parallel to the major axis direction of the defect candidate portion 43. Defect determination in which the defect candidate portion 43 is determined to be a defect 50 when the defect candidate portion 43 is within the range and the width w that minimizes the distance between the two straight lines s1 and s2 is within a predetermined range. Part 34.

  Thereby, the shape of the defect of the inspection object 10 is quantitatively extracted as a feature amount, and it is possible to identify the defect and the other with high accuracy and reduce overdetection. Therefore, according to the present embodiment, it is possible to provide the magnetic particle flaw detector 1 with an increased defect detection rate.

  In addition, the magnetic particle flaw detection apparatus 1 as a flaw detection apparatus is not limited to the above-mentioned structure. For example, the controller C and the detection device 30 may be integrally configured. That is, the controller C may be configured to include the first extraction unit 31, the inspection region generation unit 32, the second extraction unit 33, and the defect determination unit 34. With this configuration, the magnetic particle flaw detector 1 can be simplified and downsized. Furthermore, the detection apparatus 30 includes an image from which the first defect candidate portion 40 is extracted, an inspection area 41 that has been generated, an image from which the second defect candidate portion 42 has been extracted, and the second defect candidate portion 42 that has undergone expansion processing. The monitor may be configured to display data such as the detected image, the detected defect image, and the calculated determination value. With such a configuration, the defect detection result can be confirmed as appropriate, and it is easy to use.

  Furthermore, the magnetic particle flaw detector 1 may be configured to further include another controller connected to the controller C. Another controller, like the controller C, includes a processing device that performs arithmetic processing and control processing, a main storage device that stores data, and the like, for example, a CPU, a main storage device, a timer, an input circuit, an output circuit, A microcomputer including a power supply circuit and the like. The controller C includes an image obtained by extracting the first defect candidate portion 40, an image generated by the inspection area 41, an image obtained by extracting the second defect candidate portion 42, and an image obtained by expanding the second defect candidate portion 42. Then, data such as an image of the detected defect and a calculated determination value are sent to another controller. On the other hand, the other controller stores these data sent from the controller C in the main storage device in association with data such as the size and material of the object 10 stored in advance.

  With such a configuration, the mapping data of the defect of the inspection object 10 can be created by another controller, and the production management of the inspection object 10 can be easily performed. Note that the controller C may be configured to receive data such as the size and material of the inspection object 10 from another controller and create mapping data of defects of the inspection object 10.

  The flaw detection apparatus of the present disclosure is not limited to the magnetic particle flaw detection apparatus 1, and may be, for example, a penetration flaw detection apparatus that flaws the surface of the inspection object 10 using a penetrating liquid. The present invention can be applied to any flaw detection apparatus including an input device that captures the surface of the image sensor and a detection device that processes an original image acquired by the input device to detect defects on the surface.

1 Magnetic particle flaw detector (Flaw detector)
10 Inspection object 16 Camera (input device)
DESCRIPTION OF SYMBOLS 30 Detection apparatus 31 1st extraction part 32 Inspection area production | generation part 33 2nd extraction part 34 Defect determination part 40 1st defect candidate part 41 Inspection area 42 2nd defect candidate part 43 Defect candidate part 50 Defect C gravity center ( Centroid)
Lc width calculation area s1, s2 straight line w width

Claims (14)

An input device for imaging the object to be inspected;
In a flaw detection apparatus comprising a detection device that detects a defect of the inspection object from an original image acquired by the input device,
The detection device includes:
In the width calculation region having a predetermined length in the major axis direction of the defect candidate portion extracted from the original image, the defect candidate portion is between two straight lines parallel to the major axis direction of the defect candidate portion. And a defect determination unit that determines the defect candidate portion as the defect when the distance (width) between the two straight lines is within a predetermined range. The flaw detection apparatus according to claim 1, wherein the width calculation region includes a center of gravity of the defect candidate portion. The detection device includes:
A first extraction unit that binarizes the original image with a first threshold and extracts a first defect candidate portion;
An inspection region generation unit that generates an inspection region so that the first defect candidate portion is included;
A second extraction unit that binarizes the inspection region with a second threshold that is smaller than the first threshold and extracts a second defect candidate portion;
The flaw detection apparatus according to any one of claims 1 to 2, wherein the defect candidate portion is a region in which the second defect candidate portion is subjected to an expansion process. The flaw detection apparatus according to claim 3, wherein the inspection area is an area surrounded by a rectangle enlarged by a predetermined width from a minimum rectangle including the first defect candidate portion. 5. The flaw detection apparatus according to claim 3, wherein the expansion process is a process of expanding each of the second defect candidate portions in at least a major axis direction. The flaw detection apparatus comprises:
A magnetic powder spreading device for applying magnetic powder to the object to be inspected;
6. The flaw detection apparatus according to claim 1, further comprising: a magnetizing device that magnetizes the object to be inspected to form a magnetic particle indicating pattern based on a leakage magnetic flux. The flaw detector according to any one of claims 1 to 6, wherein the length of the width calculation region is 0.3 mm or more and 10 mm or less. The input device photographs the object to be inspected,
In the defect detection method by the flaw detection apparatus, wherein the detection apparatus detects the defect of the inspection object from the original image acquired by the input device.
The defect determination unit included in the detection device is parallel to the major axis direction of the defect candidate portion in a width calculation region having a predetermined length in the major axis direction of the defect candidate portion extracted from the original image. The defect candidate portion is determined to be the defect when the defect candidate portion falls between two straight lines and the distance (width) between the two straight lines is within a predetermined range. A defect detection method using a flaw detector. The defect detection method according to claim 8, wherein the width calculation region includes a center of gravity of the defect candidate portion. A first extraction unit further included in the detection device binarizes the original image with a first threshold to extract a first defect candidate portion,
An inspection region generation unit generates an inspection region so that the first defect candidate portion is included;
A second extraction unit binarizes the inspection region with a second threshold value that is smaller than the first threshold value, and extracts a second defect candidate portion;
The defect detection method according to claim 8, wherein the defect candidate portion is a region in which the second defect candidate portion is expanded. The defect by the flaw detection apparatus according to claim 10, wherein the inspection area is an area surrounded by a rectangle enlarged by a predetermined width from a minimum rectangle including the first defect candidate portion. Detection method. The defect detection method using the flaw detection apparatus according to claim 10, wherein the expansion process is a process of expanding the second defect candidate portion in at least the major axis direction. The flaw detection apparatus comprises:
A magnetic powder spreading device for applying magnetic powder to the object to be inspected;
The defect by the flaw detector according to any one of claims 8 to 12, further comprising a magnetizing device that magnetizes the object to be inspected and forms a magnetic particle indicating pattern by a leakage magnetic flux. Detection method. The defect detection method using the flaw detector according to any one of claims 8 to 13, wherein the length of the width calculation region is 0.3 mm or more and 10 mm or less.

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