KR20180123088A - Flaw detection apparatus and method for detecting defects by a flaw detection apparatus - Google Patents

Abstract

A magnetic particle flaw detection apparatus comprising a camera for photographing a subject to be inspected and a detection device for detecting a defect in the subject from an original image acquired by the camera, Between the two straight lines s1 and s2 parallel to the major axis direction of the defect candidate portion 43 in the width calculation region Lc having a predetermined length in the major axis direction of the defect candidate portion 43 extracted from the image And a defect judging section for judging the defect candidate section 43 to be defective when the defect candidate section 43 is accommodated and the distance (width w) between the two straight lines s1 and s2 is within a predetermined range.

Description

Flaw detection apparatus and method for detecting defects by a flaw detection apparatus

TECHNICAL FIELD [0001] The present invention relates to a flaw detection apparatus and a defect detection method using the flaw detection apparatus, and more particularly, to a flaw detection apparatus capable of mechanically detecting a defect in an object to be inspected, To a defect detection method.

BACKGROUND OF THE INVENTION [0002] The inspection of the surface of a test object having ferromagnetic properties such as a steel material is performed by a magnetic particle test, a penetration test, or the like, which is a non-destructive test method. Particularly, magnetic particle flaw detection is one of the most powerful methods as a method of detecting defects (cracks) which are harmful damages on the surface of an object to be inspected.

When a magnetic material is magnetized by applying a magnetic field to a steel material, a magnetic flux due to damage to the steel material is confused, and a part thereof leaks into the air as a leakage magnetic flux. At this time, if there is a magnetic powder or a magnetic fluid containing a magnetic powder on the surface of the steel, the magnetic flux is attracted to the leakage magnetic flux to form an indication shape of the magnetic powder. The magnetic particle test is to inspect the defect by observing the shape of the magnetic particle indication.

[0004] On the other hand, in the penetration test, the penetration liquid is penetrated into cracks, pinholes, and other defects that are opened on the surface of the inspected object, and the developer powder is applied to the surface from which excess impregnation liquid is removed, The capillary phenomenon forms a penetration indication by the permeate which is bleed out to the surface. Penetration testing is to inspect defects by observing these penetration instructions.

[0005] These inspection tests are expected to improve productivity, reduce costs, and improve quality by automation. Attempts have been made to automate a flaw detection apparatus for detecting a defect by image processing by putting the above-mentioned instruction shape in a camera.

[0006] Patent Document 1 discloses a technique for correcting shading in a magnetized portion generating a rotating magnetic field in the vicinity of a surface layer portion of an inspected object, shading correction of an image photographed by a camera during the generation of a rotating magnetic field, And a magnetic particle detecting device having a detecting portion.

1. Japanese Patent Application Laid-Open No. 2011-038796

According to the structure of Patent Document 1, it is possible to observe the shape of the magnetic particle designation in the rotating magnetic field, and the damaged portion with a shallow depth, which has been overlooked in the past, can be stably detected. Thus, the detection accuracy of the damaged portion is improved, The productivity is improved. However, since the magnetic flux indicating shape is formed also in the magnetic discontinuity portion which does not become a defect in the inspected object or in the change portion of the surface shape, it is not easy to distinguish such a portion from the defective portion.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a defect inspection apparatus and a defect inspection method using the defect inspection apparatus which have improved defect detection rates.

According to an aspect of the present invention, there is provided an image processing apparatus including an input device for photographing a subject to be inspected, a detection device for detecting a defect of the subject from the original image acquired by the input device, Wherein the detecting device is arranged to detect, in a width calculation region having a predetermined length in the major axis direction of the defect candidate portion extracted from the original image, a difference between the two straight lines parallel to the long axis direction of the defect candidate portion And a defect judging section for judging the defect candidate section as the defect when the defect candidate section is accommodated and the distance (width) between the two straight lines is within a predetermined range.

[0011] The width calculating region includes a center of gravity of the defect candidate portion.

[0012] The detecting apparatus may further include a first extracting section for extracting the first defect candidate section by binarizing the original image into a first threshold value (binarization), and a second extracting section for generating a check region so that the first defect candidate section is included And a second extracting unit for extracting a second defect candidate portion by binarizing the inspection region with a second threshold value smaller than the first threshold value, wherein the defect candidate portion includes a second defect candidate And is an area subjected to additional expansion processing.

[0013] The inspection area is an area surrounded by a rectangle enlarged by a predetermined width from a minimum rectangle including the first defect candidate part.

[0014] The expansion process is a process for expanding the second defect candidate portion in each of at least the major axis direction.

[0015] The flaw inspection apparatus may further comprise a magnetic particle distribution device for applying magnetic particles to the inspected object, and a magnetization device for magnetizing the inspected object to form a magnetic particle indicating shape by the leakage magnetic flux do.

[0016] The length of the width-calculating area is 0.3 mm or more and 10 mm or less.

According to the present invention, there is provided a defect detection method for a defect inspection apparatus in which an input device photographs an object to be inspected, and the detection device detects defects of the object from the original image acquired by the input device, Wherein the defect judging unit of the detecting device is arranged such that in the width calculating region having a predetermined length in the major axis direction of the defect candidate portion extracted from the original image, And when the distance (width) between the two straight lines is within a predetermined range, the defect candidate portion is determined as the defect.

[0018] The width calculating region may include a center of gravity of the defect candidate portion.

[0019] The first extraction unit further includes a detection unit that binarizes the original image to a first threshold value to extract a first defect candidate portion, and the inspection region generation unit generates an inspection region such that the first defect candidate portion is included And the second extracting unit extracts the second defect candidate portion by binarizing the inspection region with a second threshold value smaller than the first threshold value, and the defect candidate portion extracts the second defect candidate portion from the second defect candidate portion, .

[0020] The inspection region is an area surrounded by a rectangle enlarged by a predetermined width from a minimum rectangle including the first defect candidate portion.

[0021] The expansion process is characterized in that the second defect candidate portion is a process of expanding each of the second defect candidate portions in at least the major axis direction.

[0022] The flaw inspection apparatus is a magnetic particle inspection apparatus further comprising a magnetic particle distribution apparatus for applying magnetic particles to the inspected object and a magnetization apparatus for magnetizing the inspected object to form a magnetic particle indicating shape by the leakage magnetic flux do.

[0023] The length of the width-calculating area is 0.3 mm or more and 10 mm or less.

According to the present invention, there is provided a flaw detection apparatus comprising an input device for photographing an object to be inspected and a detection device for detecting a defect in the object from the original image acquired by the input device, In the width calculation region having a predetermined length in the major axis direction of the extracted defect candidate portion, 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 within a predetermined range The shape of the defect of the object to be inspected is quantitatively extracted as a characteristic quantity, and the defect and the others are identified with a high accuracy and the over detection is performed Can be reduced. Therefore, it is possible to provide a defect inspection apparatus in which the defect detection rate is improved.

Further, the width calculation region includes the center of gravity of the defect candidate portion, so that the shape of the defect of the object to be inspected can be quantitatively extracted more reliably as the feature amount, and the defect and the others are identified with higher accuracy and detected It is possible to further reduce the amount of missing and detection. Therefore, it is possible to provide a defect inspection apparatus in which the defect detection rate is further improved.

The detecting apparatus includes a first extracting unit for binarizing an original image to a first threshold value to extract a first defect candidate portion, an inspection region generating unit for generating an inspection region including the first defect candidate portion, And a second extracting unit for extracting the second defect candidate portion by binarizing the area of the defect candidate with a second threshold value smaller than the first threshold value. Since the defect candidate portion is the region subjected to the expansion processing by the second defect candidate portion, It is possible to more reliably extract the shape of the defect quantitatively as a feature amount in a state in which the detection of missing and over detection of the defect is prevented and the defect and the others can be identified with higher accuracy and the over detection can be further reduced. Therefore, it is possible to provide a defect inspection apparatus in which the defect detection rate is further improved.

Further, since the inspection region is an area surrounded by a rectangle enlarged by a predetermined width from the minimum rectangle including the first defect candidate portion, it is possible to prevent the defect from being detected and detected more reliably The shape of the defect can be quantitatively extracted as the feature amount more reliably in the state where the defect and the others are identified with higher accuracy and the detection can be further reduced. Therefore, it is possible to provide a defect inspection apparatus in which the defect detection rate is further improved.

Further, since the expansion process is a process for expanding the second defect candidate portion in each of at least the major axis direction, it is preferable that the shape of the defect is more reliably formed in a state in which the detection missing and detection of the defect of the inspected object is more reliably prevented So that it is possible to identify the defects and the other defects with higher accuracy and to further reduce the defects. Therefore, it is possible to provide a defect inspection apparatus in which the defect detection rate is further improved.

Since the fogging device is a magnetic particle detector that further includes a magnetic particle distribution device for applying magnetic particles to the inspected object and a magnetization device for magnetizing the inspected object to form a magnetic particle indicating shape by the leakage magnetic flux, The shape of the defect of the object can be more reliably extracted quantitatively as the feature amount, and the defect and the other can be identified with higher accuracy and the detection can be further reduced. Therefore, it is possible to provide a defect inspection apparatus in which the defect detection rate is further improved.

Further, since the length of the width calculating area is 0.3 mm or more and 10 mm or less, the shape of the defect of the object to be inspected can be quantitatively extracted more reliably as the characteristic quantity, and the defect and the others can be identified So that it is possible to further reduce the detection missing and detection. Therefore, it is possible to provide a defect inspection apparatus in which the defect detection rate is further improved.

Further, the present invention is a defect detection method by a flaw detector in which an input device photographs an object to be inspected, and the detection device detects defects of the inspected object from the original image acquired by the input device, The defect candidate portion is provided between the two straight lines parallel to the major axis direction of the defect candidate portion in the width calculation region having a predetermined length in the major axis direction of the defect candidate portion extracted from the original image, When the distance (width) is within the predetermined range, the defect candidate portion is judged to be defective, so that the shape of the defect of the object to be inspected is quantitatively extracted as the characteristic amount, and the defect and the others are identified with high accuracy, can do. Therefore, it is possible to provide a defect detection method using a defect inspection apparatus in which the defect detection rate is improved.

Further, the width calculating area includes the center of gravity of the defect candidate portion, so that the shape of the defect of the object to be inspected can be quantitatively extracted more reliably as a feature amount, and the defect and the others are identified with higher accuracy and detected It is possible to further reduce the amount of missing and detection. Therefore, it is possible to provide a defect detection method by a defect inspection apparatus in which the defect detection rate is further improved.

The first extraction unit further includes a detection unit for extracting the first defect candidate portion by binarizing the original image with a first threshold value to generate an inspection region such that the inspection region generation unit includes the first defect candidate portion, The second extracting unit extracts the second defect candidate portion by binarizing the inspection region to a second threshold value smaller than the first threshold value and the defect candidate portion is the region subjected to the expansion processing by the second defect candidate portion, It is possible to more reliably extract the shape of the defect quantitatively as a feature amount in a state in which the detection of missing and over detection of the defect is prevented and the defect and the others can be identified with higher accuracy and the over detection can be further reduced. Therefore, it is possible to provide a defect detection method by a defect inspection apparatus in which the defect detection rate is further improved.

Further, since the inspection region is an area surrounded by a rectangle which is enlarged by a predetermined width from the minimum rectangle including the first defect candidate portion, it is possible to more reliably prevent missing and detection of defects of the inspection object The shape of the defect can be quantitatively extracted as the feature amount more reliably in the state where the defect and the others are identified with higher accuracy and the detection can be further reduced. Therefore, it is possible to provide a defect detection method by a defect inspection apparatus in which the defect detection rate is further improved.

Further, since the expansion process is a process of expanding the second defect candidate portion in each of at least the major axis direction, it is preferable that the shape of the defect is more reliably detected in a state in which the detection missing and detection of the defect of the inspected object is more reliably prevented So that it is possible to identify the defects and the other defects with higher accuracy and to further reduce the defects. Therefore, it is possible to provide a defect detection method by a defect inspection apparatus in which the defect detection rate is further improved.

[0036] Since the flaw inspection apparatus is a magnetic particle frac- tion apparatus that further includes a magnetic particle distribution apparatus for applying magnetic particles to an object to be inspected and a magnetization apparatus for magnetizing the object to be inspected to form a magnetic particle indicating shape by the leakage magnetic flux, The shape of the defect of the object can be more reliably extracted quantitatively as the feature amount, and the defect and the other can be identified with higher accuracy and the detection can be further reduced. Therefore, it is possible to provide a defect detection method by a defect inspection apparatus in which the defect detection rate is further improved.

Since the length of the width calculating area is 0.3 mm or more and 10 mm or less, the shape of the defect of the object to be inspected can be quantitatively extracted more reliably as the characteristic quantity, and the defect and the others can be identified So that it is possible to further reduce the detection missing and detection. Therefore, it is possible to provide a defect detection method by a defect inspection apparatus in which the defect detection rate is further improved.

[0038] Fig. 1 is a schematic diagram showing a magnetic particle detector as an example of a flaw detecting apparatus according to the present embodiment.
Fig. 2 is a block diagram showing an example of a control system of the magnetic particle beam diagnosing apparatus.
3 is a flowchart for explaining an example of the detection operation of the detection device.
4 is a schematic diagram showing an example of an image binarized by the first extracting unit.
Fig. 5 is a schematic view of an image showing the extracted first defect candidate portion and an example of the generated inspection region.
6 is a schematic diagram showing an example of an image binarized by the second extracting unit.
Fig. 7 is a schematic view of an image showing an example of the extracted second defect candidate portion.
Fig. 8 is a schematic view of an image showing an example in which the second defect candidate section is expanded.
9 is a schematic diagram for explaining an example of a method of extracting a feature amount of a defect candidate portion.
10 is a schematic view of an image showing an example of the extracted defect.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, the flaw detection apparatus according to the present embodiment will be described in detail. 1 is a schematic diagram showing a magnetic particle detector 1 as an example of a flaw detection apparatus according to the present embodiment. For reference, the conveying direction of the inspected object 10 to be inspected of the magnetic particle inspection apparatus 1 is from right to left as indicated by an arrow in Fig.

The magnetic particle inspection apparatus 1 is a device that mechanically detects defects on the surface of a test article 10 having ferromagnetism or directly below (directly below) the surface thereof, to be. The magnetic particle inspection apparatus 1 illustrated in FIG. 1 is used for an inspection object having a relatively large size, and the inspected object 10 is a steel material having a long and narrow prism shape. The magnetic particle inspection apparatus 1 includes a roller conveyor 11, a magnetic particle distributing apparatus 12, a magnetizing apparatus 13, an air blow apparatus 14, an ultraviolet inspection lamp 15, a camera 16, and a marking device 17. The magnetic particle beam diagnosing apparatus 1 also includes a controller (not shown), a detecting apparatus, and the like.

The roller conveyor 11 as a conveying device conveys the inspected object 10. The roller conveyor 11 is provided with a plurality of rollers and is configured to convey the inspected object 10 at a desired speed. The roller conveyor 11 passes the position of the magnetic particle distributor 12 through the position where the magnetizing apparatus 13, the ultraviolet ray inspection lamp 15 and the camera 16 are installed and the marking apparatus 17 And is disposed in the conveying path of the inspected object 10 reaching the position. For reference, the conveying apparatus is not limited to the roller conveyor 11 as long as it is capable of conveying the inspected object 10, and may be, for example, a belt conveyor constituted by a belt or the like having a seamless endless belt shape.

In the roller conveyor 11, a conveyance distance measuring device (not shown) is provided here. The conveyance distance measuring apparatus measures the conveyance distance of the inspected object 10. As the conveyance distance measuring apparatus, for example, an apparatus in which a rotary encoder for measuring the displacement of rotation in the roller of the roller conveyor 11 is configured as a sensor can be used. For reference, the conveyance distance measuring apparatus is not limited to a rotary encoder, and a noncontact measuring apparatus such as a laser surface velocity meter may be used, or a combination thereof may be used.

The magnetic particle distributing apparatus 12 applies a magnetic particle as a mark to the surface of the inspection target 10 to be inspected and is disposed on the upstream side in the conveying direction of the inspected object 10. As the magnetic powder, for example, a fluorescent substance coated with a phosphor on the surface of a magnetic component (iron powder) is used, and a magnetic particle inspection liquid in which the fluorescent substance is dispersed in water or oil is used. The magnetic-substance dispersing device 12 is provided with, for example, a tank (not shown), a pump, a nozzle, and the like, and is configured to press-feed the magnetic particle inspection liquid contained in the tank by a pump to eject the liquid from the nozzle. The magnetic particle spraying apparatus 12 is configured to continuously spray a desired amount of magnetic particle inspection liquid on the surface of the inspected object 10.

The magnetizing apparatus 13 is magnetized by applying a magnetic field to the inspected object 10 and disposed adjacent to the downstream side of the magnetic-substance dispersing apparatus 12. The magnetizing apparatus 13 includes two through-pass coils 19 and 20 disposed opposite to the upstream side and the downstream side in the conveying direction of the inspected object 10 and a pair of through- And two inter-pole coils (21, 22) arranged in a row. The through coils 19 and 20 are formed in a ring shape and a conveying path of the inspected object 10 is disposed so as to penetrate the inside of the ring. On the other hand, the inter-pole coils 21 and 22 are formed in a U-shape, and the conveyance path of the inspected object 10 is arranged so as to pass through the gap. The magnetizing apparatus 13 is configured to generate a uniform rotating magnetic field between the two through-passing coils 19, 20 by providing the above-mentioned two inter-pole coils 21, 22.

More specifically, in the through-passing coils 19 and 20, a magnetic field is generated in the conveying direction of the inspected object 10, and in the inter-pole coils 21 and 22, the inspected object 10 A magnetic field is generated in a direction orthogonal to the direction. When an alternating current having a phase shifted by 90 degrees from the passing coils 19 and 20 and the inter-pole coils 21 and 22 flows, the magnetic field in the carrying direction and the constant current in the plane formed by the magnetic field in the direction orthogonal to the carrying direction A rotating magnetic field rotating at a magnetic field strength is generated. With this rotating magnetic field, a leakage magnetic flux is generated in the surface layer portion of the inspected object 10 irrespective of the direction of damage, and a magnetic particle indicating shape is formed.

For reference, the number of the through coils 19 and 20 and the number of the inter-pole coils 21 and 22 constituting the magnetizing apparatus 13 are appropriately designed. For example, the magnetizing apparatus 13 may have a structure in which a plurality of inter-pole coils are provided in addition to the inter-pole coils 21 and 22, while the magnetizing apparatus 13 may be constituted by one through-hole coil 19 and one inter- .

The air blowing device 14 ejects air in the direction opposite to the gravity toward the inspected object 10 and has a function of regulating the flow rate of the magnetic particle inspection liquid flowing on the surface of the inspected object 10. Then, the shape of the magnetic particle designation formed by the air blow device 14 becomes clear. The air blow device 14 is provided between the through coil 19 and the inter-pole coil 21, between the two inter-pole coils 21 and 22, and between the inter-pole coil 22 and the through- Is installed.

The ultraviolet ray inspection lamp 15 as a light source irradiates ultraviolet rays onto the magnetic particle inspection liquid on the surface of the inspected object 10 between two through-passing coils 19 and 20. In order to uniformize the intensity of ultraviolet rays in the photographing range of the camera 16, a parabolic reflector may be provided on the ultraviolet ray detector 15. It is preferable that the ultraviolet ray inspection lamp 15 is disposed at an appropriate distance from the inspected object 10, for example, about 600 mm to 2000 mm, in order to avoid the influence of the strong rotating magnetic field generated by the magnetizing apparatus 13. [ For reference, the ultraviolet ray inspection lamp 15 may be magnetically shielded.

When the surface of the magnetic component (iron powder) is, for example, a non-fluorescent substance coated with a coloring pigment such as white, black or red, the light source is preferably visible light. However, when ultraviolet light is irradiated on the fluorescent material, the magnetic particle directing shape does not shine brightly (emit light) in the visible light region, so that it is hardly affected by contamination of the surface of the inspected object 10, scale, Can be detected. Therefore, it is more preferable that the ultraviolet ray detector 15 and the fluorescent material are used.

The camera 16 as an input device photographs the surface of the inspected object 10 irradiated with ultraviolet rays by the ultraviolet ray inspection lamp 15. [ It is preferable that the camera 16 is arranged in such a manner as to take a picture from the vertical direction with respect to the surface of the inspected object 10 in order to detect the defect with higher accuracy. The camera 16 is arranged so as to be apart from the inspected object 10 by an appropriate distance, for example, about 600 mm to 2000 mm, in order to avoid the influence of the strong rotating magnetic field generated by the magnetizing apparatus 13, desirable.

[0051] As the camera 16, a line camera or an area camera may be used. Also, a CCD (Charge Coupled Device) image sensor or a CMOS (Complementary Metal-Oxide Semiconductor) image sensor may be used for an element mounted on the camera 16. [

The marking device 17 performs visual marking on defects on the surface of the inspected object 10 detected by the detecting device. As the marking device 17, for example, a marking gun for performing marking by jetting ink by air pressure can be used. For reference, the magnetic particle inspection apparatus 1 used for the inspection object having a relatively small size, for example, the marking apparatus 17 may be omitted if the defective article can be discharged to the defective product pallet.

Next, the control system of the magnetic particle test apparatus 1 according to the present embodiment will be described in detail. Fig. 2 is a block diagram showing an example of the control system of the magnetic particle beam diagnosing apparatus 1. As shown in Fig.

The magnetic particle inspection apparatus 1 includes a controller C. The controller C is provided with a roller conveyor 11, a conveyance distance measuring device 18, a magnetic particle distributing device 12, a magnetizing device 13, an air blow device 14, an ultraviolet ray inspection lamp 15 The camera 16, the marking device 17, and the detecting device 30 are electrically connected to each other. For reference, various kinds of sensors other than the configuration exemplified in Fig. 2 are electrically connected to the controller C. The magnetic particle inspection apparatus 1 is configured such that the controller C controls the above-described various devices to automatically detect defects on the surface of the inspected object 10.

The controller C reads input signals such as various set values and detection values by various sensors and outputs a control signal to control the operation of various devices provided in the magnetic particle inspection apparatus 1 . The controller C is constituted by a processing device for performing arithmetic processing and control processing, a main storage device for storing 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, It is a microcomputer. The main storage device stores a control program for executing the operation according to the present embodiment, various data, and the like. For reference, these various programs and data may be stored in a storage device provided separately from the controller C, and may be read by the controller C.

The detection device 30 reads an image signal (original image) acquired by the camera 16 and performs a predetermined process on the original image to detect defects on the surface of the inspected object 10 . In addition, the controller C is configured to cause the original image acquired by the camera 16 to be input to the detection device 30. Like the controller C, the detection device 30 is constituted by a processing device that performs arithmetic processing and control processing, a main storage device that stores data, and the like. The detection device 30 includes a CPU, a main storage device, a timer, An output circuit, a power supply circuit, and the like.

The detecting apparatus 30 has at least a defect judging section for judging whether or not the defect candidate extracted from the original image is a defect. As a result, the shape of the defect of the inspected object 10 can be quantitatively extracted as the feature amount, and the defect and the others can be identified with high accuracy and the over detection can be reduced. Therefore, it is possible to provide a defect inspection apparatus in which the defect detection rate is improved.

The detection apparatus 30 illustrated in FIG. 2 has a first extraction section 31, an inspection region generation section 32, a second extraction section 33, and a defect determination section 34 have. These parts (each part) are constituted by, for example, a program. For reference, the function of each part may be realized by hardware.

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

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

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

The defect determination section 34 is configured to input the second defect candidate section extracted by the second extraction section 33 and to detect the defect by calculating the width of the defect candidate section subjected to the expansion processing. The detection device 30 is configured to output the position data of the defect detected by the defect determination section 34 to the controller C. [

Next, the operation of the magnetic particle beam diagnosing apparatus 1 will be described in detail. The magnetic particle inspection apparatus 1 is configured such that the inspected objects 10 are sequentially conveyed to the respective devices by the roller conveyor 11 so that defects on the surface of the inspected object 10 are detected.

First, a magnetic particle inspection liquid is applied to the surface of the inspected object 10 by the magnetic particle distributor 12. The inspected object 10 to which the magnetic particle inspection liquid is applied to the surface is transported into the rotating magnetic field region formed by the magnetizing apparatus 13. At this time, if there is a damage on the surface of the inspected object 10, a leakage magnetic field due to the damage is generated, and the magnetic particles contained in the magnetic particle inspection liquid are 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 direction or the shape of the damage, and the damage is attracted to any damage. Then, the self-indicating pattern corresponding to the damage is formed on the surface of the inspected object 10 as the self is collected in the damage.

The flow rate of the magnetic particle inspection liquid flowing on the surface of the inspected object 10 is appropriately controlled by the air blow device 14. If the flow rate of the magnetic particle inspection liquid is too low, it takes a long time until the magnetic particle directing shape 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, it is difficult for the magnetic flux to be attracted to the leakage magnetic field caused by the damage, and the magnetic flux indicating shape becomes uncertain. Therefore, it is preferable that the flow rate of the magnetic particle inspection liquid is not less than 5 mm / s and not more than 100 mm / s from the viewpoint of reliably forming the magnetic particle directing shape.

[0066] The magnetic particle directing shape thus formed is a shape in which the phosphor that covers the surface of the magnetic material absorbs and excites the energy of the ultraviolet ray irradiated by the ultraviolet ray inspection lamp 15 and returns to its base state And is photographed by the camera 16 as visible light of high luminance emitted at the time of exposure. The original image acquired by the camera 16 is input to the detection device 30. [ The detecting device 30 performs a predetermined process on the original image to detect defects 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 conveyance distance measuring device 18. [ The defects on the surface of the inspected object 10 are marked by the marking device 17.

Next, a method of detecting defects by the detecting device 30 will be described in detail. In the defect detection method using the defect inspection apparatus according to the present embodiment, first, the defect determination section 34 included in the detection apparatus 30 calculates the width of the defect candidate region extracted from the original image, . If 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 within a predetermined range in the width calculation region, The defect candidate portion is judged to be defective. As described above, in the defect detection method according to the present embodiment, the shape of the defect of the inspected object 10 is quantitatively extracted as the feature amount by inputting the defect candidate portion, and the defect and the others are identified with high accuracy And detection can be reduced. Therefore, it is possible to provide a defect detection method using a defect inspection apparatus in which the defect detection rate is improved.

The defect detection method using the defect inspection apparatus according to the present embodiment may include a step of extracting the defect candidate section so as to more reliably prevent detection and detection of defects of the inspection object 10. Next, a defect detection method using such a defect inspection apparatus will be described in detail. 3 is a flowchart for explaining an example of the detection operation of the detection device 30. As shown in Fig.

First, the detecting apparatus 30 loads an image (step S1). The detection device 30 loads the image signal (original image) acquired by the camera 16 through the controller C. [ The original image is composed of pixels having a width and a length of, for example, 1280 x 960. Then, information on the photographing time is stored in the original image.

In the defect detection method using the defect inspection apparatus according to the present embodiment, defects are extracted from the original image through three processes. The first step (i) is performed by the first extracting unit 31. [

First, the first extracting unit 31 performs emphasis processing (step S2). The first extracting unit 31 performs emphasis processing on the original image using various filters as a pre-processing. The highlighting process may be a process for emphasizing the damage of the original image. For example, it may be a look up table (LUT) conversion process, an enlargement / contraction process, a shading process, or the like. For reference, emphasis processing may be omitted, but emphasis processing is preferably performed in order to increase the detection rate of defects.

Next, the first extracting unit 31 performs binarization to the first threshold value (step S 3). The first extracting unit 31 binarizes the emphasized image (the original image when emphasis processing is omitted) to a first threshold value. The first threshold value is preset 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 be able to change the first threshold value.

FIG. 4 is a schematic diagram showing an example of an image binarized by the first extracting unit 31. For reference, FIG. 4 shows pixels extracted from a portion necessary for explanation. In Fig. 4, the magnetic particle designation is indicated by black. Labeling is performed for each of the magnetic particle directing marks indicated by black. Here, the labeling is a process of attaching the same label (number) to the pixels connected in the binarized image, that is, the area closed by one contour line, and performing area division.

Then, the first extracting section 31 extracts the region corresponding to the first defect candidate section (step S 4). This is the first step. The first extracting unit 31 calculates, for example, the area, the length, the width in the longitudinal direction, and the width in the transverse direction as the criterion for each area to which the label is attached. Then, the first extracting unit 31 compares the calculated judgment value with the previously stored first judgment reference value to judge whether or not it is the first defect candidate unit, and judges whether or not the area corresponding to the first defect candidate unit .

Here, the first defect candidate region is an area assumed to be defective. Then, the first extracting unit 31 similarly judges whether or not it is the first defect candidate portion for all the regions to which the label is attached.

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

For reference, the determination value is set appropriately so long as it can compare the characteristics of the region. The determination as to whether or not the first defect candidate section 40 is to be performed may be made on the basis of one kind of determination value or on the basis of a plurality of kinds of determination values. If it is determined based on the plurality of kinds of determination values that the first defect candidate section 40 is present, the determination may be made based on at least one determination value among the plurality of determination values. For example, when at least two kinds of criterion satisfy the criterion out of the three kinds of criterion, a method of determining the region as the first defect candidate section 40 may be used.

Further, the first extracting unit 31 does not repeat Step S4 for each region, but first calculates the judgment values of all the regions, then compares the calculated judgment values and the first judgment reference value for each region , And the first defect candidate section 40 may be determined.

Next, the process proceeds to the second step (ii). The second step is performed by the inspection region generating unit 32 and the second extracting unit 33 of the detecting device 30. [

The inspection region generating unit 32 generates the inspection region 41 (Step S5). The inspection region generating unit 32 generates the inspection region 41 so that each of the first defect candidate units 40 extracted by the first extracting unit 31 includes each of them. As described above, by narrowing the inspection region 41 to the vicinity of the first defect candidate portion 40, over-detection is prevented which detects non-harmful damage, dust or the like as a defect in a region where the possibility of the defect is low. Also, the amount of computation of the detection device 30 is reduced.

FIG. 5 shows inspection regions 41a, 41b, 41c, 41d and 41e (corresponding to the first defect candidate portions 40a, 40b, 40c, 40d, 40e, 40f, , 41f, 41g, and 41h are shown. The inspection region 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 enlarged by a predetermined width in the longitudinal direction and the lateral direction from the minimum area.

[0082] For reference, the vertical width and the horizontal width may be the same or different. Here, the inspection region 41 may be a region including the first defect candidate portion 40, and may be a region surrounded by a diamond, trapezoid, circle, ellipse, or the like. The inspection area 41 may be a sloped area, for example, a rectangle extending in the major axis direction of the first defect candidate part 40, or the like.

Next, the second extracting section 33 performs emphasis processing (step S6). The second extracting section 33 performs emphasis processing on the inspection area 41 of the original image in the same manner as in step S2 by the first extracting section 31. [ Further, the detection apparatus 30 stores the image emphasized in step S2 in the main storage section, and the second extraction section 33 cuts out the inspection area 41 of the stored image so as to omit step S6 . By using such a method, the amount of calculation of the detection device 30 can be reduced.

Further, the second extracting section 33 performs binarization to the second threshold value (step S7). The second extracting unit 33 binarizes the emphasized image (the original image if emphasis processing is omitted) to a second threshold value smaller than the first threshold value. The second threshold value is preset as an appropriate value adjusted to detect a defect with high accuracy, and is stored in a main memory (not shown) of the detecting device 30. [ The detection device 30 may be configured to be able to change the second threshold value.

FIG. 6 is a schematic diagram showing an example of an image binarized by the second extracting unit 33. Referring to FIG. 6, a plurality of smaller regions are extracted as compared with FIG. 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 area of the damage is narrow or shallow, so that a region having less brightness and less brightness is also detected.

Damage is photographed in a state in which a region having a large luminance and a region having a small luminance are randomly present depending on the depth or the width, even if one is continuous. However, by binarizing to a second threshold value smaller than the first threshold value, it is possible to detect a region having a smaller luminance, so that the region corresponding to the defect can be prevented from being severed in a shallow portion or the like. Then, the second extraction unit 33 performs labeling for each shape of the magnetic particle designation of the binarized image, like the first extraction unit 31. [

Then, the second extracting section 33 extracts the region corresponding to the second defect candidate section (step S8). This is the second step. The second extracting unit 33 calculates, for example, the area, the length, the width in the longitudinal direction, and the width in the lateral direction as the judgment values for each of the areas to which the label is attached. Then, the second extracting unit 33 compares the calculated judgment value with the second judgment reference value stored in advance and judges whether or not it is the second defect candidate portion, and judges whether or not the region corresponding to the second defect candidate portion .

Here, the second defect candidate portion is an area assumed to be defective, as in the case of the first defect candidate portion. Then, the second extracting unit 33 similarly judges whether or not it is the second defect candidate portion for all the regions to which the label is attached.

The second determination reference value is a value that makes it more difficult for the region to be extracted as a defect than the first determination reference value used in the first extraction unit 31. If it is difficult to extract, it means that it is not extracted as a defect, for example, 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 also a narrow range.

[0090] Fig. 7 is a schematic view of an image showing an example of the extracted second defect candidate section 42. [0090] As shown in Fig. 7 shows a state in which the second defect candidate portion 42 is extracted with the length of the region as a judgment value and six second defect candidate portions 42a, 42b, 42c, 42e, 42f, and 42g, Is extracted. In Fig. 7, the area corresponding to the first defect candidate section 40h in Fig. 5 is not extracted. This is because it is determined that the area corresponding to the first defect candidate section 40h is not the area assumed to be defective 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 .

[0091] For reference, the determination value is set appropriately as long as it can compare the characteristics of the area. The determination as to whether or not the second defect candidate section 42 is performed may be made based on one kind of determination value or may be performed based on a plurality of kinds of determination values. If it is determined based on the plurality of types of determination values that the second defect candidate section 42 is present, the determination may be made based on at least one determination value among the plurality of determination values. For example, when at least two types of criterion satisfy the criterion out of the three kinds of criterion, a method of judging the region as the second defect candidate section 42 may be used.

[0092] For reference, the second determination reference value is not necessarily a value that is easier to extract 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 may calculate the second determination reference value based on the determination value of more kinds than the first extraction unit 31, The candidate section 42 is determined.

The second extracting section 33 does not repeat step S8 for each area in the same manner as the first extracting section 31 but calculates the judgment values of all the areas first and then calculates A comparison between the determination value and the second determination reference value, and the determination as to whether or not the second defect candidate section 42 is determined 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 determination unit 34 performs the expansion process on each of the second defect candidates 42 (step S9). Here, the expansion process is a process of expanding (expanding) the area of the second defect candidate section 42. [ The defect determination section 34 expands each of the second defect candidate sections 42 by a predetermined amount in the longitudinal direction and the lateral direction. That is, the expansion process of the defect determination section 34 is a process for expanding the second defect candidate section 42 in the outer circumferential direction. At this time, the expansion process may be extended in each of the second defect candidate portions 42 at least in the major axis direction. By such an expansion process, it is prevented that one continuous damage is cut off in the middle and is not determined as a defect, so that the detection defect is prevented from being missed. In this way, the region subjected to the expansion processing of the second defect candidate portion 42 becomes a defect candidate portion.

[0096] FIG. 8 is a schematic view of an image showing an example in which the second defect candidate section 42 is expanded. Referring to Fig. 8, for example, the three second defect candidate portions 42a, 42b, and 42c in Fig. 7 are connected in accordance with expansion processing, and one defect candidate portion 43a is formed. Like the first extracting section 31 and the second extracting section 33, the defect determining section 34 is provided with an individual defect candidate section 43 formed by expanding the second defect candidate section 42 ).

Next, the defect determination section 34 regards the defect candidate section 43 as an ellipse and approximates the ellipse, and based on the ellipse, the center of gravity of the defect candidate section 43, The long axis is calculated (step S10). Fig. 9 is a schematic diagram for explaining an example of a method of extracting the feature quantity of the defect candidate section 43a. Fig. 9 shows the center of gravity c (center point of the figure) calculated at the inner position of the defect candidate portion 43a curved in an elliptic arc shape.

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

[0099] For reference, if the width calculation area Lc is too small, there is a high possibility that non-defects will exhibit a characteristic as a defect, resulting in a high false detection rate. On the other hand, if the width calculation area Lc is too large, 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, It becomes difficult to extract the defect, and the defect detection ratio becomes high. For this reason, the length of the width-calculating area Lc is preferably 0.3 mm or more and 10 mm or less, more preferably 1 mm or more and 6 mm or less. Since the shape of the defect of the inspected object 10 is quantitatively extracted as the feature amount more reliably as the width calculation area Lc is in this range, it is possible to identify the defect and the other defects with higher accuracy, The detection can be further reduced.

All the defects, the magnetic discontinuities which do not become defects, the change of the surface shape, and the like are not easy to be discriminated near their ends. Further, as they are further away from the vicinity of the center of gravity, the inclination with respect to the major axis direction becomes larger, making it difficult to detect the correct line width. Therefore, the width calculation region Lc preferably includes the center of gravity c of the defect candidate portion 43a. Thus, since the shape of the defect of the inspected object 10 is quantitatively extracted as the feature amount more reliably, it is possible to identify the defect and the others with higher accuracy and to further reduce the detection. Here, the fact that the width calculation region Lc includes the center of gravity c of the defect candidate portion 43a means that when the line is extended from each of both ends of the width calculation region Lc in the direction perpendicular to the major axis direction, Which means that the center of gravity c is located between the two lines.

Next, the defect determination section 34 calculates the width w (step S12). The width w is such that the defect candidate portion 43a is accommodated 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 section 34 draws two straight lines s1 and s2 parallel to the major axis direction of the defect candidate section 43a on both outer sides with the defect candidate section 43a interposed therebetween. In the example of Fig. 9, a straight line s1 is drawn inside the curved inner side of the defect candidate portion 43a, and a straight line s2 is drawn outside. The defect determination section 34 approaches the defect candidate section 43a while keeping the two straight lines s1 and s2 parallel to the major axis direction. That is, the straight line s1 approaches the direction indicated by the arrow d1 and the straight line s2 approaches toward the direction indicated by the arrow d2. The positions where the straight line s1 and the straight line s2 respectively meet the outline of the defect candidate portion 43a for the first time, that is, the intersection v1 and the intersection v2 are determined. The distance between the two straight lines s1 and s2 thus determined is defined as the width w of the defect candidate portion 43a.

When the width w is within the predetermined range, the defect determination section 34 determines the defect candidate section 43a as a defect, thereby detecting the defect (step S13). The defect candidates 43e and 43f shown in Fig. 8 are similarly subjected to defect detection.

10 is a schematic view of an image in which an example of the extracted defect 50 is shown. The defect candidate portions 43e and 43f are excluded from the three defect candidate portions 43a to 43f in Fig. 8 and only the defect candidate portion 43a is determined to be the defect 50. Fig. Then, the detecting device 30 outputs the position data of the defect 50 detected by the controller C. [

[0105] The magnetic particle directive shape formed on the inspected object 10 is characterized by its formation factor. For example, the shape of the mandibles indicating harmful damage has a characteristic that the outline is clear, linear, and less broken. On the other hand, the shape of the mandibles indicating harmless damage is contour, indistinct, serrated, . This characteristic of the shape of the magnetic particle indicator is particularly remarkable in the width (w) when image processing is performed in the magnetic particle test. In this embodiment, the value of the width w is reflected in the criterion of discrimination, thereby discriminating the shape of the magnetic particle indicative of the harmful damage and the shape of the magnetic particle indicative of the other. Therefore, according to the defect detection method using the magnetic particle defect inspection apparatus 1 according to the present embodiment, it is possible to grasp the characteristic of the new magnetic particle designation shape as a value on the image processing, A more precise identification can be made between the shape of the magnetic flux indicative of the magnetic flux.

The determination as to whether the defect candidate section 43 is the defect 50 may be made based on another judgment value in addition to the width w. At this time, as in step S4, if a method of determining whether or not a defect is used is used based on a comparison with the defect determination reference value, for example, the area, the length, the width in the longitudinal direction, good. At this time, the determination by the width w may be given priority. The defect determination reference value may be a value that makes it difficult for the region to be extracted as a defect than the second determination reference value in the second extraction unit 33. [

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

The detection device 30 may be configured so as to be able to appropriately change values such as threshold values, reference values for determination, and width calculation regions. This makes it possible to appropriately change the size of the defect detected as a defect, and to appropriately adjust the inspection accuracy of the defect, which is convenient to use.

As described above, in the present embodiment, the camera 16 photographs the inspected object 10, and the detecting device 30 detects the inspected object 10 from the original image acquired by the camera 16, The defect determination section 34 included in the detection apparatus 30 determines whether or not the defect candidate section 43 extracted from the original image has been read in advance in the major axis direction of the defect candidate section 43 The defect candidate portion 43 is accommodated between two straight lines s1 and s2 parallel to the major axis direction of the defect candidate portion 43 in the width calculation region Lc having a predetermined length and the two straight lines s1, s2 is within a predetermined range, the defect candidate section 43 is judged to be defect 50. In this case,

Thus, the shape of the defect of the inspected object 10 can be quantitatively extracted as the feature amount, and the defect and the others can be identified with high accuracy and the over detection can be reduced. Therefore, according to the present embodiment, it is possible to provide a defect detection method using the magnetic particle inspection apparatus 1 with improved detection rate of defects.

The magnetic particle inspection apparatus 1 according to the present embodiment is provided with a camera 16 for photographing the inspected object 10 and a defective portion of the inspected object 10 from the original image acquired by the camera 16. [ And the detection device 30 detects the defective candidate 43 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 width w at which the defect candidate portion 43 is accommodated between the two straight lines s1 and s2 parallel to the longitudinal direction of the portion 43 and the distance between the two straight lines s1 and s2 is minimum, , The defect candidate section 43 has a defect determination section 34 that determines the defect 50 as the defect 50. [

Thereby, the shape of the defect of the inspected object 10 can be quantitatively extracted as the feature amount, and the defect and the others can be identified with high accuracy and the over detection can be reduced. Therefore, according to the present embodiment, it is possible to provide the magnetic particle test apparatus 1 with improved detection rate of defects.

The magnetic particle beam diagnosing apparatus 1 as a flaw detecting apparatus is not limited to the above-described configuration. For example, the controller C and the detection device 30 may be integrally formed. That is, the controller C may be configured to include the first extracting section 31, the inspection region generating section 32, the second extracting section 33, and the defect determining section 34. With such a configuration, the magnetic particle test apparatus 1 is simplified and the size is reduced. The detection device 30 is further provided with the image obtained by extracting the first defect candidate section 40, the generated inspection area 41, the image from which the second defect candidate section 42 is extracted, the second defect candidate section 42 May be provided with a monitor for displaying data such as an image of the defect candidate section 43 subjected to expansion processing, an image of the detected defect 50, and a calculated judgment value. With this configuration, it is possible to confirm the detection result of the defect appropriately, and it is convenient to use.

The magnetic particle test apparatus 1 may further include another controller connected to the controller C. [ The other controller, like the controller C, is constituted by a processing device for performing arithmetic processing and control processing, a main memory device for storing data, and the like. The other controller includes a CPU, a main memory device, a timer, an input circuit, Circuit and the like. The controller C determines whether or not the first defect candidate section 40 is extracted, the generated inspection region 41, the second defect candidate section 42 is extracted, and the second defect candidate section 42 is expanded The image of the processed defect candidate section 43, the image of the detected defect 50, the calculated judgment value, and the like 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 inspected object 10 previously stored.

With such a configuration, mapping data of the defect 50 of the inspected object 10 can be created by another controller, and production control of the inspected object 10 can be easily performed. The controller C may be configured to receive data such as the size and material of the inspected object 10 from other controllers and to generate mapping data of the defects 50 of the inspected object 10.

Industrial availability

The inspection apparatus of the present invention is not limited to the magnetic particle inspection apparatus 1 but may be a penetration inspection apparatus for detecting defects on the surface of the inspection target 10 using a permeating liquid, And a detection device for detecting a defect on the surface by processing the original image acquired by the input device.

1: Magnetic particle detector (flaw detector)
10: Inspection object
16: Camera (input device)
30: Detection device
31: First extraction section
32: Inspection area generating unit
33: second extracting section
34:
40: First defect candidate part
41: Inspection area
42: second defect candidate part
43: Defect Candidate
50: Defective
c: center of gravity (center of drawing)
Lc: width calculation area
s1, s2: straight line
w: Width

Claims (14)

An input device for photographing a subject to be inspected,
A detecting device for detecting a defect of the inspected object from the original image acquired by the input device;
And a detection unit
The detection device includes:
The defect candidate portion is accommodated between two straight lines 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, Width judging section judges the defect candidate section as the defect when the width of the defect is within the predetermined range,
Flaw detection device. The method according to claim 1,
And the width calculation region includes a center of gravity of the defect candidate portion.
Flaw detection device. 3. The method according to claim 1 or 2,
The detection device includes:
A first extracting unit for extracting a first defect candidate by binarizing the original image to a first threshold value,
An inspection region generating unit for generating an inspection region so that the first defect candidate portion is included;
A second extracting unit for extracting the second defect candidate by binarizing the inspection area to a second threshold value smaller than the first threshold value,
Lt; / RTI >
And the defect candidate portion is an area in which the second defect candidate portion is subjected to expansion processing
Flaw detection device. The method of claim 3,
Wherein the inspection region is an area surrounded by a rectangle enlarged by a predetermined width from a minimum rectangle including the first defect candidate portion
Flaw detection device. The method according to claim 3 or 4,
Wherein the expansion process is a process for expanding the second defect candidate portion in each of at least the major axis direction
Flaw detection device. 6. The method according to any one of claims 1 to 5,
The above-
A magnetic particle spray device for applying magnetic particles to the inspected object,
A magnetizing device for magnetizing the inspected object to form a magnetic particle indicating shape by the leakage magnetic flux
Is a magnetic particle inspection apparatus further comprising:
Flaw detection device. 7. The method according to any one of claims 1 to 6,
And the length of the width calculating area is not less than 0.3 mm and not more than 10 mm
Flaw detection device. The input device photographs the inspected object,
A method for detecting a defect in a detection device for detecting a defect in an object to be inspected from an original image acquired by the input device,
Wherein the defect judging unit of the detecting device is arranged such that in the width calculating region having a predetermined length in the major axis direction of the defect candidate portion extracted from the original image, And judges the defect candidate portion as the defect when the distance (width) between the two straight lines is within a predetermined range.
A defect detection method by a flaw detection device. 9. The method of claim 8,
Wherein the width calculating region includes a center of gravity of the defect candidate portion
A defect detection method by a flaw detection device. 10. The method according to claim 8 or 9,
A first extracting unit having the detecting device further includes a binarizing unit that binarizes the original image to a first threshold value to extract a first defect candidate portion,
The inspection area generating unit generates an inspection area such that the first defect candidate unit is included,
The second extraction unit extracts the second defect candidate portion by binarizing the inspection region to a second threshold value smaller than the first threshold value,
And the defect candidate portion is an area in which the second defect candidate portion is subjected to expansion processing
A defect detection method by a flaw detection device. 11. The method of claim 10,
Wherein the inspection region is an area surrounded by a rectangle enlarged by a predetermined width from a minimum rectangle including the first defect candidate portion
A defect detection method by a flaw detection device. The method according to claim 10 or 11,
Wherein the expansion process is a process for expanding the second defect candidate portion in each of at least the major axis direction
A defect detection method by a flaw detection device. 13. The method according to any one of claims 8 to 12,
The above-
A magnetic particle spray device for applying magnetic particles to the inspected object,
A magnetizing device for magnetizing the inspected object to form a magnetic particle indicating shape by the leakage magnetic flux
Is a magnetic particle inspection apparatus further comprising:
A defect detection method by a flaw detection device. 14. The method according to any one of claims 8 to 13,
And the length of the width calculating area is not less than 0.3 mm and not more than 10 mm
A defect detection method by a flaw detection device.

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