JP2008151653A - Inspection device, inspection method, inspection program and inspection system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect a defect such as a crack generated on a weld bead. <P>SOLUTION: This inspection device for inspecting a measuring object having a welding area where a weld hardware is welded is equipped with a welding area specification part 11 for specifying a welding area from a radiographic image of the measuring object; a weld bead specification part 12 for specifying the weld bead in the welding area; a crack detection part 13 for detecting a crack in the weld bead; a storage part 14 for storing the first table correlating the thickness of the weld bead with brightness and the second table correlating a crack depth with the brightness relative to each thickness of the weld bead; and a crack depth specification part 15 for specifying the thickness of the weld bead by using the first table, and specifying the crack depth detected by the crack detection part 13 by using the second table corresponding to the specified thickness of the weld bead. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an inspection apparatus that inspects an object to be measured using X-rays.

2. Description of the Related Art Conventionally, a technique is known in which an X-ray image is taken of an object to be measured, and a crack generated in the object to be measured and its depth are detected from the captured image.
For example, Patent Document 1 discloses an apparatus for inspecting the remaining thickness of a workpiece cleavage groove. In the apparatus disclosed in Patent Document 1, X-ray imaging is performed on a workpiece that is an object to be measured, the density of the groove is obtained from the X-ray image, and the depth of the groove is determined based on the information on the density. ing.
JP 2005-114628 A

By the way, in a boiler tube used in a power plant or the like, there are defects such as a crack called groove corrosion on the outer surface of the boiler tube and a crack on the back side of the weld bead (inner surface of the boiler tube) of the welded portion of the boiler tube. Often occurs.
Among these, since the thickness of the weld bead is not uniform with respect to a crack occurring on the back side of the weld bead, in the conventional inspection method based on the density information of the X-ray image as described above, a normal location However, there is a problem in that it is impossible to specify the gray level information of the image and to detect a defect.
Furthermore, since cracks occurring on the back side of the weld bead are not regular in the direction of occurrence, this makes it more difficult to detect defects.

  The present invention has been made to solve the above problems, and provides an inspection apparatus, an inspection method, an inspection program, and an inspection system capable of detecting defects such as cracks occurring in a weld bead. Objective.

In order to solve the above problems, the present invention employs the following means.
The present invention is an inspection apparatus for inspecting an object to be measured having a welded part to which a weld metal is welded, and a welding part specifying means for specifying the welded part from an X-ray image of the object to be measured, Welding bead specifying means for specifying a weld bead in the weld site, crack detecting means for detecting a crack in the weld bead, first information for associating the thickness and brightness of the weld bead, and each thickness of the weld bead Storage means for storing the second information for associating the crack depth and the brightness, and using the first information, the thickness of the weld bead is specified, and the specified thickness of the weld bead is supported. There is provided an inspection apparatus comprising crack depth specifying means for specifying the depth of a crack detected by the crack detecting means using the second information.

According to such a configuration, the welded part including the weld metal and the weld bead is specified by the welded part specifying means, the weld bead in the welded part is specified by the weld bead specifying means, and further, the crack detecting means is used. Cracks generated in the weld bead are detected, and the depth of each crack is specified by the crack depth specifying means.
In this case, the crack depth specifying means uses the first information in which the relationship between the crack depth and the brightness is associated, specifies the thickness of the weld bead in which the crack is generated from the brightness, Using the second information in which the crack depth and the brightness in the specified weld bead are associated in advance, the depth is specified from the brightness of the crack part, so even if the thickness of the weld bead is individually different, The crack depth can be obtained in consideration of the thickness of the weld bead. Thereby, the detection accuracy of the crack depth can be improved.

  In the inspection apparatus, the welding site specifying means sets a plurality of regions in the X-ray image of the object to be measured, correlates adjacent regions, and specifies the welding site based on the correlation. It is good.

  Since a welded part including a weld metal has a different pixel value (for example, brightness) than other parts, the welded part can be easily identified by comparing the correlation values.

  In the inspection apparatus, the welding part specifying unit sets a plurality of areas in the X-ray image of the object to be measured, acquires information on luminance in each area, and specifies the welding part based on the information. It is good as well.

  Since the weld metal has a higher brightness than the other parts, the brightness of the region including the welded portion is higher than that of the other region. Therefore, a welding site can be easily specified by comparing information on luminance in each region.

  In the inspection apparatus, the area is set to a size including the weld metal, for example.

  The weld metal is welded to the object to be measured in various directions. Therefore, by setting the region to a size that includes all of the welded metal welded in all directions, a welded part including the welded metal can be efficiently detected.

In the inspection apparatus, the welding part specifying unit may specify the welding direction based on the correlation value and the luminance.
Thus, the detection accuracy of a welding site | part can be improved by specifying a welding site | part using a correlation value and a brightness | luminance.

  In the inspection apparatus, the crack detection means differentiates the weld bead region specified by the weld bead specifying means, creates a gradient direction histogram based on the differentiation result, and generates a crack based on the gradient direction histogram. It may be detected.

  According to such a configuration, edge components that are candidates for cracks are detected by differentiating the inside of the weld bead. Since the edge component includes a noise component and a crack component, it is necessary to exclude the noise component from the detected edge component. Here, in the present invention, attention is paid to the fact that the direction of cracks occurring in the same weld bead is uniform, and cracks and noise are discriminated from this viewpoint. Therefore, a gradient direction histogram is created based on the strength and direction of the edge component, the direction with the highest value in this gradient direction histogram is specified as the crack occurrence direction, and the edge component belonging to this direction is defined as a crack. Thus, only cracks can be extracted efficiently.

  In the inspection apparatus, the crack detection means differentiates the region of the weld bead specified by the weld bead specifying means, creates a gradient direction histogram based on the differentiation result, and generates a crack direction based on the gradient direction histogram. The candidate may be detected, and the crack may be detected based on the detected crack candidate and the luminance of the vicinity region.

  According to such a configuration, an edge component that is a candidate for a crack is extracted based on the gradient direction histogram, and further, a crack is detected based on the luminance in the vicinity of the edge component, thereby improving the crack detection accuracy. be able to.

In the inspection apparatus, the crack detection unit may perform contour tracking from the detected end point of the crack, and may detect a portion detected by the contour tracking as a crack.
When the crack is bent, the method of extracting only the edge component in the same direction causes a portion that is not detected as a crack. Therefore, by performing contour tracking from the end point of the edge component detected as a crack, when the crack is bent, it is possible to detect the bent portion.

In the inspection apparatus, the crack detection unit may identify a direction of the crack based on the gradient direction histogram, and may rotationally correct the X-ray image according to the direction.
In this way, it is possible to match all crack directions by rotationally correcting the X-ray image according to the crack generation direction. Thereby, subsequent image processing and the like can be performed uniformly, so that the processing load can be reduced.

  The inspection apparatus is suitable for use in boiler tube defect detection inspection and the like.

  The present invention is arranged on the opposite side of the X-ray irradiation device via the X-ray irradiating means for irradiating the X-ray with respect to the DUT having a welded portion to which a weld metal is welded. Radiation measuring means for storing X-ray information of the object to be measured, reading processing means for reading out X-ray information stored in the radiation measuring means and forming image data, and the object processed by the reading processing means. An inspection device that detects a defect from an X-ray image of the object to be measured, the inspection device including a welding region specifying means for specifying the welding region from the X-ray image of the object to be measured; Welding bead specifying means for specifying a weld bead, crack detecting means for detecting a crack in the weld bead, first information for associating the thickness and brightness of the weld bead, and the crack depth for each thickness of the weld bead. Sato Storage means for storing second information for associating a degree, and using the first information, the thickness of the weld bead is specified, and the second information corresponding to the specified thickness of the weld bead is specified. There is provided an inspection system comprising crack depth specifying means for specifying the depth of a crack detected by the crack detecting means using the information.

In the above inspection system, when the object to be measured is X-rayed, the object to be measured is divided into an area where there is a high possibility of cracking and an area where the crack is likely to occur, and imaging is performed with different imaging conditions for each area. It may be done.
In this way, for an area where there is a high possibility that a crack has occurred, it is possible to acquire an X-ray image that is easy to detect a crack by performing imaging under imaging conditions suitable for detecting the crack. Become. Thereby, it becomes possible to improve the crack detection accuracy, crack depth detection accuracy, and the like.

In the inspection system, the X-ray irradiating means may be provided with heat detecting means for detecting heat, and the radiation measuring means may be provided with a plurality of heating elements.
According to such a configuration, the X-ray irradiation unit and the radiation measurement unit can be easily aligned by detecting the heat from the heating element provided in the radiation measurement unit by the heat detection unit. .

In the inspection system, the X-ray irradiating means may be provided with sound detecting means for detecting sound, and the radiation measuring means may be provided with a sound source.
According to such a configuration, the X-ray irradiation unit and the radiation measurement unit can be easily aligned by detecting the sound emitted from the sound source provided in the radiation measurement unit by the sound detection unit. it can.

  The present invention is an inspection method for inspecting an object to be measured having a welded part to which a weld metal is welded, and a welding part specifying process for specifying the welded part from an X-ray image of the object to be measured; Using a first information that associates a weld bead identifying process for identifying a weld bead in a weld site, a crack detection process for detecting a crack in the weld bead, and the thickness and brightness of the weld bead, The depth of the crack detected in the crack detection process is determined by using the second information that associates the weld bead thickness specifying process for specifying the thickness with the crack depth and the brightness at the specified thickness of the weld bead. Provided is an inspection method including a crack depth specifying process for specifying.

  The present invention is a welding site specifying method for specifying the welding site from an X-ray image of an object to be measured having a welding site to which a weld metal is welded, and a plurality of X-ray images of the object to be measured are included in the X-ray image. Provided is a welding site specifying method for setting a region, calculating a correlation value between adjacent regions, and specifying the welding site based on the correlation value.

  In the welding site specifying method, information on luminance in a plurality of the regions may be acquired, and the welding site may be specified based on the luminance and the correlation value.

  In the welding site specifying method, the area is set to a size including the weld metal, for example.

  The present invention is a crack detection method for detecting a crack generated in a weld bead at the weld site from an X-ray image of an object to be measured having a weld site to which a weld metal is welded. A crack detection method is provided in which a region is differentiated, a gradient direction histogram is created based on the differentiation result, and a crack is detected based on the gradient direction histogram.

  The present invention is a crack detection method for detecting a crack generated in a weld bead at the weld site from an X-ray image of an object to be measured having a weld site to which a weld metal is welded. Differentiate the region, create a gradient direction histogram based on this differentiation result, detect crack candidates based on this gradient direction histogram, and detect cracks based on the detected crack candidate and the brightness of its neighboring regions A crack detection method is provided.

  In the crack detection method, contour tracking may be performed from the detected end point of the crack, and a portion detected by the contour tracking may be detected as a crack.

  The present invention is an inspection program for inspecting an object to be measured having a welded part to which a weld metal is welded, and a welding part specifying process for specifying the welded part from an X-ray image of the object to be measured; The first information for associating a weld bead specifying process for specifying a weld bead in the weld site, a crack detection process for detecting a crack in the weld bead, and the thickness and brightness of the weld bead, Using the second information that associates the weld bead thickness specifying process for specifying the thickness of the weld bead with the crack depth and the luminance in the specified weld bead thickness, the crack detected in the crack detecting process Provided is an inspection program for causing a computer to execute a crack depth specifying process for specifying a depth.

  According to the present invention, it is possible to detect a defect such as a crack generated in a weld bead.

Hereinafter, an embodiment of an inspection system according to the present invention will be described with reference to the drawings.
In this embodiment, as an object to be measured, a boiler tube having a welded part to which a weld metal is welded is taken as an example, and the position and depth of cracks and corrosion generated in the weld bead of this boiler tube are mainly described. The case of measuring will be described. The boiler tube to be inspected includes a rifle tube in which a groove for increasing thermal efficiency called a rib is formed inside the tube, a bare tube without a rib, etc., but the present invention is applied to both of them. Is possible.

  FIG. 1 is a block diagram showing a schematic configuration of an inspection system according to the present embodiment. As shown in FIG. 1, the inspection system according to the present embodiment inspects an object to be measured using X-ray imaging. In recent years, an imaging plate has been developed as a new digital X-ray imaging system replacing X-ray photography. This imaging plate is an X-ray information recording medium that replaces a conventional photographic film. It has a higher sensitivity to radiation than a photographic film and can be used repeatedly because it can erase captured information. Has the advantage of being able to. Further, since the X-ray information can be extracted as a digital signal, there is an advantage that the processing by a computer is easy. In the present embodiment, an X-ray image is created using the imaging plate, and the object to be measured is inspected mainly by image processing using the X-ray image.

  As shown in FIG. 1, an inspection system according to this embodiment includes an X-ray irradiation device (X-ray irradiation means) 2 that irradiates a boiler tube 1 that is a measurement object, and a boiler tube 1. An imaging plate (radiation measurement means) 3 for storing X-ray information of the boiler tube 1 and an X-ray information stored in the imaging plate 3 are read out to form image data. CR (Computed Radiography) system 4, inspection apparatus 5 that performs corrosion / crack inspection of boiler tube 1 using an X-ray image of boiler tube 1 created by CR system 4, and inspection results by inspection apparatus 5 And a display device 6 for displaying.

  The CR system 4 is an imaging system that takes out X-ray information accumulated in the imaging plate 3 as an image, and is a known system that has been developed in recent years. Specifically, the CR system 4 reads the X-ray image information as light emission proportional to the X-ray dose received by the imaging plate 3, quantizes it, and generates a histogram (frequency curve), thereby generating X-rays from the boiler tube 1. Create a shot image.

  The inspection device 5 is a main characteristic part of the present invention, and as shown in FIG. 2, a welding part specifying part (welding part specifying means) 11 for specifying a welding part from an X-ray image of the boiler tube 1, and a welding part A weld bead specifying part (weld bead specifying means) 12 for specifying a weld bead in the inside, a crack detecting part (crack detecting means) 13 for detecting a crack in the weld bead, and the thickness and brightness of the weld bead are associated with each other. Storage unit (second information) for storing the first table (first information) and the second table (second information) in which the crack depth and the brightness are associated with each weld bead thickness. The storage means) 14 and the first table are used to specify the thickness of the weld bead, and further, the second table corresponding to the specified weld bead thickness is used to detect the weld bead. Identify crack depth And a crack depth identifying section 15 that.

  The inspection device 5 includes a computer system including, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. A series of processing procedures for realizing the functions of the above-described units is recorded in a computer-readable recording medium such as a ROM in the form of a program, and the CPU reads the program into a RAM or the like to process and process information. By executing the arithmetic processing, functions such as the welded part specifying unit 11, the weld bead specifying unit 12, the crack detecting unit 13, and the crack depth specifying unit 15 are realized.

  As shown in FIG. 3, the weld site specifying unit 11 sets a plurality of rectangular regions Si (i = 1 to n) in the X-ray image P of the boiler tube 1 and correlates the adjacent rectangular regions Si. Take. At this time, the length L1 of the rectangular region Si along the longitudinal direction of the boiler tube 1 is set to be longer than the length L2 of the welded metal J in the longitudinal direction. The size of the weld metal J is assumed to be known. Further, the “welded part” refers to a region including a weld metal J and a weld bead (not shown). The correlation value can be calculated using, for example, normalized cross-correlation or absolute value difference.

Subsequently, as shown in FIG. 3, the welded part specifying unit 11 compares the correlation values between the adjacent rectangular areas, and shows a correlation value that is smaller than the correlation value of the adjacent rectangular areas by a predetermined value or more. Si is specified as a welding site. For example, in the case of FIG. 3, the rectangular region Sm is specified as the welding site.
Here, for example, in the X-ray image P, the correlation values between the adjacent regions are high in the rectangular regions that do not include the weld metal J, and the correlation between the rectangular region that includes the weld metal J and the rectangular region that does not include the weld metal J. The value becomes lower. Therefore, by referring to the correlation value, it is possible to easily identify the welded part including the welded metal J.

In addition to or instead of the above correlation, the welding site specifying unit 11 obtains an average luminance in each rectangular region Si, and obtains a rectangular region Si whose average luminance is higher than the average luminance of adjacent regions by a predetermined value or more. It is good also as specifying as a welding part.
For example, since the weld metal J has high brightness in the X-ray image P, the average brightness of the rectangular area Si including the weld metal J tends to be higher than the average brightness of the rectangular area Si not including the weld metal J. is there. Therefore, it is possible to easily specify the welded portion including the weld metal J by referring to the average luminance.

Then, the welding part specific | specification part 11 detects the joining direction of the metal joint J in the rectangular area | region Sm specified as a welding part.
Specifically, as shown in FIG. 4, the welded part specifying unit 11 has a length L1 in the vertical direction equal to or longer than the length L3 of the short side of the joint metal J with respect to the rectangular region Sm specified as the welded part. Preferably, a plurality of rectangular areas Si ′ (i = 1 to n) set to be slightly longer than L3 are set, and the correlation values of adjacent rectangular areas Si are taken.
Subsequently, the welded part specifying unit 11 specifies a rectangular area having a correlation value lower than the adjacent rectangular area by a predetermined value or more, and further calculates the average luminance of the specified rectangular area and the average luminance of the adjacent rectangular area. Calculate the difference. As a result, if the difference is equal to or greater than a preset reference value, the welding site specifying unit 11 determines that the welding direction of the weld metal J is a lateral direction, and if the difference is less than the reference value, the weld metal. The welding direction of J is determined to be the longitudinal direction or the oblique direction.

  For example, when the welding direction is the horizontal direction, as shown in FIG. 4, the rectangular region in which the correlation value is lower than the surroundings includes most parts of the welded hardware J. The average luminance of the image is considerably higher than the average luminance of the adjacent rectangular areas. On the other hand, when the welding direction is the vertical direction or the oblique direction, as shown in FIG. 5, not only the rectangular area where the correlation value is lower than the surrounding area, but also the rectangular area adjacent thereto, Since the part portion is included, the luminance difference is small compared to the case where the joining direction shown in FIG. 4 is the horizontal direction. Therefore, it is possible to easily determine whether or not the joining direction is the lateral direction by comparing the average luminance of adjacent rectangular regions.

  In the determination result, when the welding direction is not the horizontal direction, the welding site specifying unit 11 specifies whether the welding direction is the vertical direction or the diagonal direction. Specifically, as shown in FIG. 6, the welding site specifying unit 11 sets a plurality of vertically long rectangular regions Si ″ for the rectangular region Sm specified as the welding site, and each rectangular region Si ″. Find the correlation value at. Here, the vertical length L1 of the rectangular region Si ″ is set to be slightly longer than the length L2 of the weld metal J in the longitudinal direction. Further, the lateral length W1 of the rectangular region Si ″ is set to be slightly longer than the width W2 of the welded metal J in the width direction.

  Subsequently, the welding site specifying unit 11 specifies a rectangular region whose correlation value is lower than a predetermined value by comparison with other regions, and further shows a region width indicating a correlation value lower than the surrounding correlation value by a predetermined value or more. If D is greater than the length W2 in the width direction of the joint metal J, it is determined that the welding direction of the weld metal J is the vertical direction. On the other hand, as shown in FIG. If the region width D showing the low correlation value is smaller than the width W2 of the joint hardware J in the width direction, it is determined that the welding direction of the weld metal J is an oblique direction. In this way, by specifying the welding direction, it becomes possible to easily extract the edge of the weld metal described later.

As described above, in addition to the method of detecting the joining direction based on the correlation value, the welding direction may be determined according to the projection pattern of the rectangular region Si specified as the welding site, as shown below. Good. For example, as shown in FIG. 8, when the welding direction is vertical, the projection value in the horizontal direction is narrow and the projection value in the vertical direction is wide. As shown in FIG. 9, when the welding direction is horizontal, the projection value in the horizontal direction is wide and the projection value in the vertical direction is narrow. Furthermore, as shown in FIG. 10, when the welding direction is oblique, the projection value in the horizontal direction is wide and the projection value in the vertical direction is also wide.
The joint part specifying part 11 can specify the welding direction of the joint hardware J based on the characteristics of the projection pattern by having the projection pattern characteristics in each joining direction as described above in advance. . In addition, when the welding direction cannot be specified by the projection pattern, the welding direction is specified by using the correlation value as described above.

As described above, when the welded part is specified by the welded part specifying unit 11, the weld bead specifying unit 12 specifies the weld bead in the welded part.
The relative positional relationship between the weld bead and the weld metal J is known. Therefore, if the weld metal J can be specified, the weld bead can be specified based on the relative positional relationship between the weld metal J and the weld bead. For example, the weld bead is formed along the longitudinal contour of the weld metal J.

Hereinafter, the processing procedure of the welding bead specifying method performed by the weld bead specifying unit 12 will be described.
First, the weld bead specifying unit 12 detects the contour (edge) of the welded hardware J by performing image processing such as differential processing and Hough transformation in the welded part specified by the welded part specifying unit 11. For edge detection, a known method can be used. Since the weld metal J has a higher brightness than other parts, a portion where the brightness changes is extracted using a differential filter or the like, and a Hough transform is performed to extract only the edge in the above-described welding direction (angle). Thus, the contour of the weld metal J can be easily extracted.

  Next, the weld bead specifying unit 12 specifies the weld bead by setting a weld bead region in the vicinity of the weld metal J based on the relative positional relationship between the weld metal and the weld bead that is held in advance. For example, the weld bead specifying unit 12 sets a weld bead Jx having a predetermined size along the longitudinal direction of the weld metal J as shown in FIG.

When the weld bead Jx is specified in this way, the crack detection unit 13 detects a crack in the weld bead Jx.
First, the crack detection unit 13 detects edges by performing differential processing in the weld bead Jx, and calculates the direction and strength of each detected edge. Furthermore, the crack detection unit 13 quantizes the direction of the edge into several directions. For example, quantization is performed in four directions of 0 °, 45 °, 90 °, and 135 °. As a result, for example, cracks and noise included in an X-ray image in the weld bead Jx as shown in FIG. 12 are shown as lines whose edge directions are quantized as shown in FIG. Become.

Next, the crack detection unit 13 creates a gradient direction histogram based on the quantized gradient direction and intensity. Specifically, the crack detection unit 13 creates a gradient direction histogram as shown in FIG. 14 by accumulating the edge strength in each pixel shown in FIG. 13 for each quantized direction. Subsequently, in the gradient direction histogram as shown in FIG. 14, the crack detection unit 13 regards the direction having the largest histogram value as the crack direction, and the edge components in the other directions are noise. Judge.
For example, as shown in FIG. 14, when the histogram at 45 ° shows the largest value, it is determined that the edge component indicating 45 ° is a crack, and the other direction, that is, 0 °. , 90 °, and 135 ° edge components are determined to be noise components.

Here, the crack generation direction in the weld bead Jx differs depending on each weld bead Jx, but the crack generation direction in the same weld bead Jx tends to be uniform. Therefore, as described above, by focusing on the relationship between the direction and strength of the edge component in each weld bead Jx, it is possible to determine the noise and crack in each weld bead Jx.
When detecting the crack, the crack detection unit 13 rotationally corrects the X-ray image P so that the direction of the crack matches a preset reference direction, for example, 0 °.
Thereby, the direction of the crack which has generate | occur | produced in each welding bead Jx can be unified between X-ray imaging images P, and efficiency, such as subsequent image processing, can be improved.
In the case of a boiler pipe having ribs, the ribs may be detected in advance, and the above-described processes may be executed only in a region where no ribs are present.

  Further, as shown in FIG. 15, the crack detection unit 13 further performs contour tracking from the end point of the detected crack after detecting the crack according to the above-described procedure, and also cracks the edge component detected by the contour tracking. It is good also as detecting as. As described above, by detecting the edge component whose contour is traced as a crack, it is possible to extract a crack that is bent in the middle. Thereby, the crack detection accuracy can be improved.

In addition, as shown in FIG. 16, the crack detection unit compares the brightness of the edge component obtained by the differentiation process with the brightness of the neighboring pixels as a process before quantizing the edge component. It is good also as discriminating primarily whether it is noise or a crack.
For example, in the case of a crack, the luminance tends to be lower than that of the surroundings, but in the case of noise, the luminance tends to be higher than that of the surroundings. Therefore, edge components with higher luminance than the surroundings are excluded as noise components, and only the remaining edge components are identified as cracks and noise by creating the above-described gradient direction histogram and the like. Also good.

In this way, when a crack is detected by the crack detection unit 13, the crack depth specifying unit 15 detects the depth of the crack. Hereinafter, the crack depth identification method will be described in detail.
First, in the storage unit 14, a first table in which the weld bead thickness and brightness are associated with each other, and a second table in which the crack depth and brightness are associated with each weld bead thickness. And are stored.

The first table and the second table are tables created as follows, for example.
First, a plurality of test boiler tubes made of the same material as the boiler tube 1 are prepared as a pre-stage of actual inspection of the boiler tube 1 that is the object to be measured, and each test boiler tube has a different thickness. Forming a known weld bead. An X-ray image is acquired by irradiating each of these test boiler tubes with X-rays under substantially the same conditions as in the actual inspection. Subsequently, the brightness of the weld bead in each X-ray image is detected, a table for associating the brightness with the thickness of the weld bead is created, and this table is stored in the storage unit 14 as a first table.

  Subsequently, a crack having a different depth is artificially formed in the known weld bead having the different thickness, and the test boiler tube is irradiated with X-rays under substantially the same conditions as the actual inspection. Thus, an X-ray image is acquired. And the brightness | luminance of each crack in the weld bead of this X-ray image is detected, the table which matches the brightness | luminance and crack depth of each crack is produced, and this table is stored in the memory | storage part 14 as a 2nd table. At this time, the second table is created corresponding to the thickness of each weld bead.

  FIG. 17 shows an example of the first table, and FIG. 18 shows an example of the second table. In FIG. 17, the horizontal axis indicates the thickness of the weld bead, and the vertical axis indicates the luminance. In FIG. 18, the horizontal axis indicates the crack depth and the vertical axis indicates the luminance.

The crack depth specifying unit 15 specifies the depth of a crack generated in the weld bead Jx by using such a first table and a second table. Specifically, when receiving the X-ray image P in the weld bead in which a crack is detected from the crack detection unit 13, the crack depth specifying unit 15 first uses the first table to determine the thickness of the weld bead Jx. Further, the depth of the crack generated in the weld bead is detected by using the second table corresponding to the thickness of the specified weld bead.
Thereby, even if the thickness of the weld bead is different, the depth of the crack can be obtained, so that the measurement accuracy can be further improved.

  In place of the first table and the second table, function expressions of these tables are held, and the thickness of the weld bead and the crack depth are obtained by calculation based on the function expressions. It is good as well.

  In addition, as shown in FIG. 19, when the thickness Q of the weld bead Jx changes gently, the brightness of the areas A1 and A2 in the vicinity of the place Ax where the crack is generated is detected, and this brightness is calculated. It is good also as calculating | requiring the brightness | luminance of the location Ax in which the crack has generate | occur | produced by interpolating, and calculating | requiring the thickness of the weld bead corresponding to this brightness | luminance from a 1st table. As described above, when the thickness of the weld bead is gradually changed, the thickness can be specified based on the luminance of the cracked portion from the luminance around the weld bead.

Next, the operation of the inspection system according to the present embodiment described above will be described.
First, the X-ray irradiation apparatus 2 is disposed in the vicinity of the boiler tube 1 that is the object to be measured, and the imaging plate 3 is disposed on the opposite side of the X-ray irradiation apparatus 2 through the boiler tube 1. X-ray information from the boiler tube 1 is accumulated in the imaging plate 3 by irradiating the boiler tube 1 with X-rays 2.

  The X-ray information accumulated in the imaging plate 3 is read by the CR device 4, image data is created, and transferred to the inspection device 5. The X-ray image of the boiler tube 1 transferred to the inspection device 5 is input to the welded part specifying unit 11 in the inspection device 5. The weld site specifying unit 11 specifies a weld site including the weld bead and the weld metal J in the X-ray image, and the information on the weld site is transferred to the weld bead specifying unit 12. In the weld bead specifying unit 12, the weld metal J in the welded part is extracted, and the region of the weld bead Jx is set along the longitudinal direction of the weld metal J. The X-ray image P in which the weld bead Jx is specified is transferred to the crack detection unit 13.

In the crack detection unit 13, an edge component in the weld bead is extracted, and a gradient direction histogram is created based on the strength and direction of the edge component. Subsequently, noise and cracks are discriminated based on this gradient direction histogram, and after the edge component detected as a crack is rotationally corrected by a predetermined amount, this X-ray image P is output to the crack depth specifying unit 15.
In the crack depth specifying unit 15, the thickness of the weld bead Jx is specified based on the brightness near the crack occurrence location and the first table, and further, a second table corresponding to the thickness of the weld bead Jx. The crack depth corresponding to the crack brightness is identified.

The crack depth obtained by the crack depth determination unit 15 is transferred to the display control unit (not shown) together with the position information of the crack site, and display image data is created by the display control unit and displayed on the display device 6. Is displayed.
Thereby, the operator can easily grasp the occurrence location of cracks and the depth of the cracks in the weld bead of the boiler tube by checking the display screen of the display device 6. In this way, it is possible to provide the operator with information effective for grasping the life of the boiler tube 1 and the like.

  As described above, according to the inspection system according to the present embodiment, the thickness of the weld bead Jx is determined from the luminance of the weld bead Jx where the crack is generated, and the luminance and crack at the specified weld bead thickness are determined. Since the depth of the crack is specified by using the second table in which the depth is associated, the crack depth can be detected regardless of the thickness of the weld bead Jx.

In the inspection system according to the above-described embodiment, an X-ray image may be acquired by the following procedure.
First, as shown in FIG. 20, a plurality of X-ray images are acquired while scanning the imaging region F horizontally and vertically over the entire inspection region C of the boiler tube as the object to be measured. The shooting conditions at this time are set so as to extract cracks of all depths from shallow cracks to deep cracks. Examples of imaging conditions include the tube voltage of the X-ray source.

Subsequently, by confirming each X-ray image, a region S1 in which a crack may be generated is extracted from the inspection region C of the boiler tube. Thereby, a place where there is no possibility of occurrence of cracks is excluded from the target.
Subsequently, an X-ray image is acquired again by imaging the region S1 under imaging conditions suitable for detecting cracks, and each inspection process described above is performed using the X-ray image. Thereby, the detection accuracy of cracks and the detection accuracy of crack depth can be improved.

For example, when imaging the entire inspection region C of the boiler tube, the tube voltage of the X-ray source is set to a high voltage. This enables crack detection even when the tube is thick.
Further, when an X-ray image is acquired again for an area where cracks may occur, the tube voltage of the X-ray source is changed according to the thickness of the tube in that area. For example, a place where the pipe is thick, for example, a portion where the rifle pipe is thick or a weld bead is photographed at a high voltage. On the other hand, when the tube is thin, for example, a thin rifle tube or a tube portion is photographed at a low voltage. As described above, when the tube is thin, a clear image can be obtained by photographing at a low voltage, so that the accuracy of estimation of the crack depth can be improved.

Moreover, at the time of imaging | photography, it is good also as acquiring several X-ray imaging images by changing the imaging | photography angle with respect to a boiler tube. For example, it is preferable to photograph from a plurality of angles such as front (90 °), 45 degrees oblique, and 135 degrees.
In many cases, the depth of a fatigue crack is larger than the width of the crack. Therefore, by photographing from an oblique direction, it is possible to obtain an X-ray image in which a crack appears clearly, and it is possible to improve crack detection accuracy and crack depth identification accuracy.

  Further, as shown in FIG. 21, the X-ray irradiation apparatus 2 may be provided with a heat detection sensor (heat detection means) 31, and a plurality of heating elements 32 may be provided at the four corners of the imaging plate 3. At the time of imaging, the imaging plate 3 provided with the heating elements 32 at the four corners is attached to the imaging area of the boiler tube 1 to cause the heating elements 32 to generate heat. By detecting the positions of the heating elements 32 provided at the four corners of the imaging plate 3 by the heat sensing sensor 31 provided in the X-ray irradiation apparatus 2, the installation positions of the imaging plate 3 are detected. An X-ray irradiation area is set based on the installation position.

As described above, by providing the heating element 32 on the imaging plate 3, it is possible to easily detect the installation position of the imaging plate 3, and the X-ray irradiation region can be easily set.
It should be noted that the X-ray irradiation region can be set more easily by integrating the X-ray source and the heat detection sensor 31 in advance. An example of the heat detection sensor 31 is an infrared camera.

  Further, instead of the alignment by the heat generation described above, the sound source 33 is provided at the four corners of the imaging plate 3 and the sound sensor 34 is provided at the X-ray irradiation apparatus 2 to set the X-ray irradiation region. Good. In this case, the installation position of the imaging plate 3 is detected by detecting the sound emitted from the sound source 33 provided on the imaging plate 3 with the sound sensor 34 provided on the X-ray irradiation apparatus 2.

  Note that the installation positions of the heating element 32 and the sound source 33 are not limited to the four corners of the imaging plate 3. These heating elements 32 or sound sources 33 may be provided at two or more locations, and may be attached at regular intervals along the outer periphery of the imaging plate 3, for example.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the specific structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

  For example, in the above-described embodiment, the case where the inspection is performed using the imaging plate 3 is illustrated, but the present invention is not limited to this. For example, the inspection method described above may be realized by reading an X-ray film converted into digital information by a film scanner into an inspection apparatus. Furthermore, a flat panel detector (FPD) system in which an image receiver and a reader are integrated may be used.

  In addition, the inspection system of the present invention is not only applied to the above-described inspection of the boiler tube 1, but is preferably used in various fields. In particular, in a measurement object whose background brightness changes, it is possible to eliminate the influence of disturbances such as the background and accurately measure the depth of the crack, so that a great merit can be obtained.

It is a schematic structure figure of an inspection system concerning one embodiment of the present invention. It is the figure which showed schematic structure of the inspection apparatus of this invention. It is a figure for demonstrating the procedure which detects a junction part. It is a figure for demonstrating the procedure which specifies a welding direction. It is a figure for demonstrating the procedure which specifies a welding direction. It is a figure for demonstrating the procedure which specifies a welding direction. It is a figure for demonstrating the procedure which specifies a welding direction. It is a figure for demonstrating the case where a welding direction is specified based on a brightness | luminance. It is a figure for demonstrating the case where a welding direction is specified based on a brightness | luminance. It is a figure for demonstrating the case where a welding direction is specified based on a brightness | luminance. It is a figure for demonstrating the identification method of a weld bead. It is a figure for demonstrating the procedure which detects a crack. It is a figure for demonstrating the procedure which detects a crack. It is a figure for demonstrating the procedure which detects a crack. It is a figure for demonstrating the case where a crack is detected by performing outline tracking from the end point of an edge. It is a figure for demonstrating the case where a crack is detected in consideration of a brightness | luminance. It is the figure which showed an example of the 1st table. It is the figure which showed an example of the 2nd table. It is a figure for demonstrating the procedure which detects the thickness of the crack generation location in case the thickness of a weld bead changes gently. It is a figure for demonstrating the acquisition method of a radiography image. It is a figure for demonstrating position alignment with an X-ray irradiation apparatus and an imaging plate. It is a figure for demonstrating position alignment with an X-ray irradiation apparatus and an imaging plate.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Boiler tube 2 X-ray irradiation apparatus 3 Imaging plate 4 CR system 5 Inspection apparatus 6 Display apparatus 11 Welding site | part specific part 12 Weld bead specific part 13 Crack detection part 14 Memory | storage part 16 Crack depth specific part

Claims (22)

An inspection apparatus for inspecting an object to be measured having a welded portion to which a weld metal is welded,
Welding part specifying means for specifying the welding part from an X-ray image of the object to be measured;
Welding bead specifying means for specifying a weld bead in the weld site;
Crack detecting means for detecting cracks in the weld bead;
Storage means for storing first information for associating the thickness and luminance of the weld bead, and second information for associating crack depth and luminance for each thickness of the weld bead;
The thickness of the weld bead is specified using the first information, and the crack depth detected by the crack detection means is determined using the second information corresponding to the specified thickness of the weld bead. An inspection apparatus comprising: a crack depth specifying means for specifying the thickness.   2. The welding part specifying unit according to claim 1, wherein the welding part specifying unit sets a plurality of regions in an X-ray image of the object to be measured, correlates adjacent regions, and specifies the welding part based on the correlation. Inspection device.   The welding part specifying means sets a plurality of areas in an X-ray image of the object to be measured, acquires information about luminance in each area, and specifies the welding part based on the information. Inspection equipment.   The inspection apparatus according to claim 2 or 3, wherein the region is set to a size including the welded hardware.   The inspection apparatus according to any one of claims 1 to 4, wherein the welding part specifying unit specifies a welding direction based on the correlation value and luminance.   The crack detection means differentiates a weld bead region specified by the weld bead specifying means, creates a gradient direction histogram based on the differentiation result, and detects a crack based on the gradient direction histogram. The inspection apparatus according to claim 5.   The crack detection means differentiates the region of the weld bead specified by the weld bead specifying means, creates a gradient direction histogram based on the differentiation result, detects a crack candidate based on the gradient direction histogram, The inspection apparatus according to any one of claims 1 to 5, wherein a crack is detected based on the detected candidate for the crack and the luminance of a neighboring region.   The inspection apparatus according to claim 6 or 7, wherein the crack detection unit performs contour tracking from the detected end point of the crack, and also detects a portion detected by the contour tracking as a crack.   The inspection apparatus according to any one of claims 6 to 8, wherein the crack detection means specifies the direction of the crack based on the gradient direction histogram and rotationally corrects the X-ray image according to the direction. .   The inspection device according to claim 1, wherein the object to be measured is a boiler tube. X-ray irradiating means for irradiating the object to be measured having a welded portion to which the weld metal is welded,
A radiation measuring means disposed on the opposite side to the X-ray irradiation device via the object to be measured, and storing X-ray information of the object to be measured;
Reading processing means for reading X-ray information stored in the radiation measuring means and forming image data;
An inspection device for detecting a defect from an X-ray image of the object to be measured processed by the reading processing means,
The inspection device includes:
Welding part specifying means for specifying the welding part from an X-ray image of the object to be measured;
Welding bead specifying means for specifying a weld bead in the weld site;
Crack detecting means for detecting cracks in the weld bead;
Storage means for storing first information for associating the thickness and luminance of the weld bead, and second information for associating crack depth and luminance for each thickness of the weld bead;
The thickness of the weld bead is specified using the first information, and the crack depth detected by the crack detection means is determined using the second information corresponding to the specified thickness of the weld bead. An inspection system comprising: a crack depth specifying means for specifying the thickness.   12. The apparatus according to claim 11, wherein when the object to be measured is X-rayed, the object to be measured is divided into an area where the possibility of cracking is high and an area where the crack is likely to occur, and the imaging conditions for each area are different. The inspection system described.   The inspection system according to claim 11 or 12, wherein the X-ray irradiation means is provided with a heat detection means for detecting heat, and the radiation measurement means is provided with a plurality of heating elements.   The inspection system according to claim 11 or 12, wherein the X-ray irradiation means is provided with sound detection means for detecting sound, and the radiation measurement means is provided with a sound source. An inspection method for inspecting an object to be measured having a welded portion to which a weld metal is welded,
A welding part specifying process for specifying the welding part from an X-ray image of the object to be measured;
A welding bead specifying process for specifying a weld bead in the weld site;
A crack detection process for detecting cracks in the weld bead;
Using a first information for associating the thickness of the weld bead with the brightness, a weld bead thickness specifying process for specifying the thickness of the weld bead;
An inspection method comprising: a crack depth specifying step for specifying the depth of the crack detected in the crack detection step by using the second information for associating the crack depth and the luminance in the specified thickness of the weld bead . A welding site specifying method for specifying the welding site from an X-ray image of a measurement object having a welding site to which a weld metal is welded,
A welding site specifying method in which a plurality of regions are set in an X-ray image of the object to be measured, a correlation value between adjacent regions is calculated, and the welding site is specified based on the correlation value.   The welding site specifying method according to claim 16, wherein information on luminance in a plurality of the regions is acquired, and the welding site is specified based on the luminance and the correlation value.   The welding region specifying method according to claim 16 or 17, wherein the region is set to a size including the welding hardware. A crack detection method for detecting a crack occurring in a weld bead of the welded part from an X-ray image of a measurement object having a welded part to which a weld metal is welded,
A crack detection method for differentiating the weld bead region, creating a gradient direction histogram based on the differentiation result, and detecting a crack based on the gradient direction histogram. A crack detection method for detecting a crack occurring in a weld bead of the welded part from an X-ray image of a measurement object having a welded part to which a weld metal is welded,
Differentiating the region of the weld bead, creating a gradient direction histogram based on the differentiation result, detecting a crack candidate based on the gradient direction histogram, and based on the detected brightness of the crack candidate and its neighboring region A crack detection method for detecting cracks.   The crack detection method according to claim 19 or 20, wherein contour tracking is performed from the detected end point of the crack, and a portion detected by the contour tracking is also detected as a crack. An inspection program for inspecting an object to be measured having a welded portion to which a weld metal is welded,
A welding part specifying process for specifying the welding part from an X-ray image of the object to be measured;
A weld bead specifying process for specifying a weld bead in the weld site;
Crack detection processing for detecting cracks in the weld bead;
Weld thickness specification processing for specifying the thickness of the weld bead using the first information that associates the thickness of the weld bead with the brightness;
Causing the computer to execute a crack depth specifying process for specifying the crack depth detected in the crack detection process, using the second information that associates the crack depth and the luminance in the specified thickness of the weld bead with each other. Inspection program for.

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