JP2015010912A - Measurement device and measurement method for inspected material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a measurement device and a measurement method for an inspected material, allowing suppression of generation of a non-inspection region in nondestructive inspection and allowing suppression of appearance of an excessive overlap inspection region by measuring a feed pitch (a flaw detection pitch), an axial direction speed, or a circumferential direction speed of the inspected material over the full length.SOLUTION: A device measuring a feed pitch or the like for an inspected material 10 carried in an axial direction while rotating the inspected material 10 around an axis in nondestructive inspection includes: an application device 31 applying a paint to the outer circumferential face of the carried inspected material in a dot state at a constant time interval; a camera 32 imaging the outer circumferential face applied with the paint in the dot state of the carried inspected material; detection means detecting coordinates of the paint applied in the dot state from a captured image; correction means correcting the detected coordinates of the dot-like applied paint such that the coordinates indicate a distance in a state that the outer circumferential face of the inspected material is developed to a plane; and calculation means calculating the feed pitch or the like by use of the corrected coordinates of the dot-like applied paint.

Description

  The present invention relates to an apparatus and a method for measuring a feed pitch and the like of a material to be inspected that is conveyed in the axial direction while rotating around an axis in nondestructive inspection. More specifically, by measuring the feed pitch (flaw detection pitch) of the material to be inspected over the entire length, it is possible to suppress the occurrence of an uninspected area in nondestructive inspection and to suppress an excessively overlapping inspection area. The present invention relates to a measuring apparatus and a measuring method for an inspection object.

Unless otherwise stated, the definitions of terms in this specification are as follows.
“Material to be inspected”: A material that is transported in the axial direction while rotating around an axis during non-destructive inspection. For example, a tubular material or a rod-shaped material is applicable, and more specifically, a steel pipe or a round steel. Is applicable.

  In nondestructive inspection such as ultrasonic flaw detection, since the entire length of the inspection object is inspected over the entire length, a flaw detection sensor (for example, an ultrasonic probe) is relatively moved along the circumferential direction of the inspection object. While rotating, it is necessary to move relatively along the axial direction of the material to be inspected. As such a method, there is a method in which the flaw detection sensor is fixed by so-called spiral conveyance, and the material to be inspected is moved in the axial direction while rotating around the axis. Further, there is a method of moving the flaw detection sensor in the axial direction of the material to be inspected while rotating the material to be inspected, and this method is easily adopted for nondestructive inspection of a large diameter material. There is also a method of moving the flaw detection sensor in the circumferential direction of the material to be inspected while moving the material to be inspected in the axial direction, and this method is easily adopted in nondestructive inspection of small diameter materials.

  Spiral transport has a wide range of dimensions that can be transported, and is easily compatible with other varieties. Therefore, spiral transport is frequently used in non-destructive inspection on a steel pipe production line. However, there is a problem that it is difficult to control the feed pitch, the axial speed, and the circumferential speed, which are distances in which the flaw detection material moves in the axial direction per rotation, and it becomes difficult to control the flaw detection pitch determined by these. .

  For this reason, various proposals have been conventionally made regarding spiral conveyance in non-destructive inspection. Patent Document 1 describes a method of spirally transporting a material to be inspected by using spherical rollers disposed at a predetermined interval upstream and downstream of a nondestructive inspection device. In Patent Document 1, a target feed pitch and a target peripheral speed of a material to be inspected are determined in advance by spiral conveyance with a spherical roller, and the skew angle of the spherical roller is determined based on a predetermined calculation formula using the target feed pitch and the target peripheral speed. Set. The material to be inspected is transported under the set conditions, and the transport speed at that time is calculated from the detection signal from the photoelectric tube and the data of the motor speed detection encoder. Thereafter, the skew angle is corrected and controlled so that the target transport speed determined by the target feed pitch and the target peripheral speed is obtained.

  Thereby, in patent document 1, it is supposed that a to-be-inspected material can be conveyed with a target feed pitch. Further, in Patent Document 1, as a method of actually measuring the feed pitch of a material to be inspected spirally, marking is continuously performed on the material to be inspected spirally using a chalk or the like, and offline (after spiral conveyance). ) A method for actually measuring the pitch of the chalk mark is described.

Japanese Patent Publication No.62-21058

  In the nondestructive inspection, the material to be inspected may be flaw-detected over the entire length by spirally conveying the material to be inspected. In this case, the flaw detection pitch is determined by the feed pitch of the material to be inspected by spiral conveyance, and the flaw detection pitch affects the defect detection capability. This is because when the flaw detection pitch is larger than the axial range that can be inspected by the flaw detection sensor, an uninspected area is generated. On the other hand, if the flaw detection pitch is too smaller than the axial range that can be inspected by the flaw detection sensor, the overlapping inspection area increases. This is because the inspection efficiency decreases.

  In spiral conveyance for nondestructive inspection, a skew angle is set for the skew roller, and the flaw detection pitch is controlled by adjusting the skew angle. In order to convey the material to be inspected while rotating the material to be inspected from the entrance side to the exit side, a plurality of skew rollers need to be arranged at a predetermined interval in the conveyance direction (longitudinal direction) of the flaw detection material.

  In such spiral conveyance, it is difficult to make the skew angles of the plurality of skew rollers completely coincide with each other due to variations in the dimensions of the skew rollers and play of the skew roller holding mechanism. For this reason, since the feed pitch, the axial speed, and the circumferential speed are different for each skew roller, the feed pitch varies depending on the combination of the skew rollers in contact with the material to be inspected. Therefore, it is difficult to inspect at a uniform flaw detection pitch over the entire length of the material to be inspected. In order to uniformize the flaw detection pitch over the entire length of the material to be inspected, it is desired to measure the feed pitch over the entire length. If the feed pitch or the like can be measured over the entire length, the flaw detection pitch over the entire length of the material to be inspected can be made uniform by feeding back the measured feed pitch or the like to the adjustment of the skew angle of the skew roller.

  Moreover, the start of flaw detection by the flaw detection sensor can be performed, for example, by detecting the leading end of the material to be inspected spirally by an end detection sensor (for example, a proximity sensor). Specifically, the flaw detection sensor starts flaw detection after a predetermined time has elapsed since the detection of the leading end of the inspection object by the end detection sensor. In this case, the predetermined time is a time required for the end portion on the leading side of the inspection object to be conveyed from the position of the end detection sensor to the position of the flaw detection sensor. Such a predetermined time can be calculated by dividing the distance from the edge detection sensor to the flaw detection sensor by the axial speed of the inspection object.

  On the other hand, the end of flaw detection by the flaw detection sensor can be performed by detecting the end on the rear side of the material to be inspected spirally by an end detection sensor (for example, a proximity sensor), similarly to the start of flaw detection described above. . Specifically, the flaw detection by the flaw detection sensor is terminated after a predetermined time has elapsed since the detection of the rear end of the material to be inspected by the end detection sensor. In this case, the predetermined time is the time required for the rear end of the material to be inspected to be transported from the position of the end detection sensor to the position of the flaw detection sensor. This predetermined time can also be calculated by dividing the distance from the edge detection sensor to the flaw detection sensor by the axial speed of the inspection object.

  When calculating the time required for the leading or trailing edge of the inspection material to be transported from the edge detection sensor position to the flaw detection sensor position, the target value is set as the axial speed of the inspection material. If used, an uninspected area may occur when the difference between the target value and the actual speed is large. For this reason, it is desired to actually measure the axial speed of the material to be inspected over the entire length.

  In Patent Document 1 described above, as a method of actually measuring the feed pitch of the material to be inspected spirally, marking is continuously performed on the material to be inspected spirally using chalk or the like, and offline (after spiral conveyance). Describes a method of actually measuring the pitch of the chalk mark. However, the method for measuring the feed pitch described in Patent Document 1 has an error due to marking using a chalk or the like, or actual measurement of the pitch on the outer peripheral surface of the inspected material having curvature, and the accuracy is not sufficient.

  In Patent Document 1, the conveyance speed of the material to be inspected is calculated from the detection signal from the phototube and the data of the encoder for detecting the speed of the motor. However, in actual conveyance, slippage occurs between the roller and the material to be inspected. Therefore, the measurement of the conveyance speed described in Patent Document 1 has an error in the conveyance speed calculated using the data of the motor speed detection encoder. Contained and not accurate enough.

  The present invention has been made in view of such circumstances, and has not been inspected by nondestructive inspection by measuring the feed pitch (flaw detection pitch), axial speed, and circumferential speed of the material to be inspected over its entire length. An object of the present invention is to provide a measurement apparatus and a measurement method for a material to be inspected that can suppress the occurrence of a region and suppress an excessive overlap inspection region.

  In order to solve the above problems, the present inventors conducted various tests, and as a result of intensive studies, applied the paint to the outer surface of the material to be inspected in a dotted manner at regular time intervals with a camera. It has been found that if an image is taken and the image is analyzed, the feed pitch (flaw detection pitch), axial speed and circumferential speed of the material to be inspected can be measured over the entire length.

  The present invention has been completed on the basis of the above knowledge, and the gist of the following (1) to (4) measuring device measuring device and the following (5) to (8) measuring method. Is:

(1) In non-destructive inspection, an apparatus for measuring at least one of a feed pitch, an axial speed, and a circumferential speed for a material to be inspected that is transported in the axial direction while rotating around an axis, A coating device that applies the paint to the outer peripheral surface of the material to be inspected at regular time intervals, and a camera that images the outer peripheral surface of the material to be inspected that is coated with the paint in a point shape The detection means for detecting the coordinates of the paint applied in a spot form from the measured image and the coordinates of the detected spot paint applied are corrected so as to indicate the distance in a state where the outer peripheral surface of the material to be inspected is flattened. And a calculating means for calculating at least one of a feed pitch, an axial speed, and a circumferential speed by using the corrected coordinates of the dotted application paint. Measuring device.

(2) The calculation means extracts a first group of dot-like coating paints distributed in a predetermined axial range, and is adjacent to the first group and distributed in a predetermined axial range. (2), wherein a second group of spot paints is extracted, and an axial distance between an approximate straight line obtained from the first group and an approximate straight line obtained from the second group is used as the feed pitch. The measuring device for the material to be inspected according to 1.

(3) The calculation means extracts a first group of point-like coating paints distributed in a predetermined axial range, selects two points belonging to the first group, and sets the axis according to the following equation (1). The apparatus for measuring a material to be inspected as described in (1) above, wherein a direction velocity VA (mm / second) is calculated.
VA = DA / {(N + 1) TP} (1)
Here, DA is the axial distance (mm) between the two selected points, N is the number of points existing between the two selected points, and TP is the time interval (seconds) at which the paint is applied in the form of dots. .

(4) The calculation means extracts a first group of dot-like coating paints distributed in a predetermined axial range, selects two points belonging to the first group, and calculates the circumference according to the following equation (2). The apparatus for measuring a material to be inspected according to (1) above, wherein a direction velocity VC (mm / second) is calculated.
VC = DC / {(N + 1) TP} (2)
Here, DC is the circumferential distance (mm) between the two selected points, N is the number of points existing between the two selected points, and TP is the time interval (seconds) at which the paint is applied in the form of dots. .

(5) In a non-destructive inspection, a method for measuring at least one of a feed pitch, an axial speed, and a circumferential speed for a material to be inspected that is transported in an axial direction while rotating around an axis, Coating the outer peripheral surface of the material to be inspected in spots at regular time intervals, imaging the outer peripheral surface of the material to be inspected in which the paint is applied in spots, and imaging Detecting the coordinates of the paint applied in the form of dots from the obtained image, and correcting the coordinates of the detected application of the dots in the form of dots so as to indicate the distance in a state where the outer peripheral surface of the inspection object is developed on a plane. And a step of calculating at least one of a feed pitch, an axial speed, and a circumferential speed by using the corrected coordinates of the dot-like coating material to be corrected. Method.

(6) When calculating the feed pitch using the corrected coordinates of the dotted application paint, a first group consisting of the dotted application paint distributed in a predetermined axial range is extracted; A second group consisting of dotted application paints adjacent to the first group and distributed in a predetermined axial range is extracted, and an approximate straight line obtained from the first group and an approximate straight line obtained from the second group The method for measuring a material to be inspected according to (5) above, wherein the feed pitch is calculated by calculating the axial distance.

(7) When calculating the axial speed using the corrected coordinates of the point-like coating paint, a first group of point-like coating paints distributed in a predetermined axial range is extracted, and The method for measuring a material to be inspected according to (5) above, wherein two points belonging to the first group are selected and the axial velocity VA (mm / sec) is calculated by the following equation (1).
VA = DA / {(N + 1) TP} (1)
Here, DA is the axial distance (mm) between the two selected points, N is the number of points existing between the two selected points, and TP is the time interval (seconds) at which the paint is applied in the form of dots. .

(8) When calculating the circumferential speed using the corrected coordinates of the punctiform coating paint, a first group consisting of punctiform coating paint distributed in a predetermined axial range is extracted, and The method for measuring a material to be inspected as described in (5) above, wherein two points belonging to the first group are selected and the circumferential velocity VC (mm / sec) is calculated by the following equation (2).
VC = DC / {(N + 1) TP} (2)
Here, DC is the circumferential distance (mm) between the two selected points, N is the number of points existing between the two selected points, and TP is the time interval (seconds) at which the paint is applied in the form of dots. .

  The measuring apparatus and measuring method for a material to be inspected according to the present invention can measure the feed pitch, axial speed, and circumferential speed over the entire length of the material to be inspected spirally. Thereby, it is possible to suppress the occurrence of an uninspected area in the non-destructive inspection, and it is possible to suppress the overlapping inspection area from becoming excessive.

It is a schematic diagram explaining the structural example of the measuring apparatus of the to-be-inspected material which concerns on this invention. It is a schematic diagram explaining the correction | amendment process of this invention, the figure (a) is a front view, and the figure (b) is a side view. It is a schematic diagram which shows distribution of the corrected point-like coating paint.

  Below, the measuring apparatus and measuring method of the to-be-inspected material of this invention are demonstrated.

[Inspection material measuring device]
FIG. 1 is a schematic diagram illustrating a configuration example of a measuring apparatus for a material to be inspected according to the present invention. The figure shows a tube 10 that is a material to be inspected, a skew roller 20 that spirally conveys the tube, a flaw detection sensor 70 of a nondestructive inspection device, and a measurement device 30 for the material to be inspected. In the same figure, the direction in which the transported pipe 10 moves in the axial direction is indicated by hatched arrows, and the direction in which the pipe 10 is rotated in the circumferential direction is indicated by solid arrows. An inspection material measuring device 30 shown in FIG. 1 includes a coating device 31, a camera 32, and a personal computer 40. Further, the flaw detection sensor 70 of the nondestructive inspection apparatus is disposed at a stage subsequent to the position where the coating apparatus 31 applies the paint and before the area captured by the camera 32.

  In the non-destructive inspection, the measuring device 30 of the inspection material of the present invention has at least one of a feed pitch, an axial speed, and a circumferential speed for the inspection material conveyed in the axial direction while rotating around the axis. It is a device to measure. Nondestructive inspection corresponds to, for example, ultrasonic flaw detection and overcurrent flaw detection.

  The coating device 31 applies the coating material in a dotted manner to the outer peripheral surface of the material to be inspected spirally at regular time intervals. What is necessary is just to set suitably the time interval which applies a coating material according to a feed pitch and the conveyance speed of the circumferential direction. Although the coating material is applied in the form of dots by a coating device, there is no limitation on the shape and size of the coating material as long as the applied coating material (hereinafter also simply referred to as “coating material”) can be detected by an image captured by a camera. . For example, a circular shape or a rectangular shape can be adopted as the shape of the dot-like coating material. As such a coating apparatus, for example, a paint injection machine of a system in which paint is dropped and sprayed on a material to be inspected can be employed. The paint is preferably an aqueous paint so that it can be easily washed away in the next step.

  The camera 32 is arranged at the rear stage of the coating device 31 and images a portion of the outer peripheral surface to be transported where the coating material is applied in a dotted shape of the material to be inspected. As the camera 32, for example, a CCD camera can be used. From the viewpoint of simplifying the processing using the image captured by the camera 32, the camera 32 is set so that the vertical or horizontal center position of the image captured by the camera 32 is the center of the outer peripheral surface of the inspection object. It is preferable to arrange.

  The personal computer 40 functions as detection means, correction means, and calculation means. The personal computer 40 can be composed of, for example, a main body 41, a monitor 42, a mouse (not shown), and a keyboard (not shown). In the main body 41, a program is executed to realize the detecting means, the correcting means, and the calculating means. The main body 41 receives an image picked up by the camera 32, and the program operates to perform processing by the detection means, correction means, and calculation means, and measure the feed pitch, axial speed, and circumferential speed.

  The detection means detects the coordinates of the paint applied in the form of dots from the captured image. Further, the correcting means corrects the detected coordinates of the dotted application paint so as to indicate the distance in a state where the outer peripheral surface of the inspection object is developed on a plane. The calculation means calculates at least one of the feed pitch, the axial speed, and the circumferential speed using the corrected coordinates of the dotted application paint. Regarding such detection means, correction means, and calculation means, specific processing contents and preferred forms will be described later.

  Such a measuring apparatus for a material to be inspected according to the present invention images the material to be inspected conveyed by the camera 32 over a full length at a predetermined time interval, and includes a detecting means, a correcting means and a calculating means from the picked-up image. If the feed pitch or the like is calculated by using it, the feed pitch or the like can be measured over the entire length.

[Measurement method of inspection material]
In the non-destructive inspection, the method for measuring a material to be inspected of the present invention measures at least one of a feed pitch, an axial speed, and a circumferential speed with respect to the inspected material that is conveyed in the axial direction while rotating around the axis. It is a method to do. Nondestructive inspection corresponds to, for example, ultrasonic flaw detection and overcurrent flaw detection.

  In the method for measuring a material to be inspected according to the present invention, the coating material is applied in a dotted manner to the outer peripheral surface of the material to be inspected at regular time intervals. The application of the paint can be performed by, for example, the coating device 31 provided in the measuring device 30 shown in FIG. The time interval at which the paint is applied and the shape and size of the dot-like applied paint can be set in the same manner as in the above-described measuring apparatus for a material to be inspected. The paint is preferably an aqueous paint so that it can be easily washed away in the next step.

  In the method for measuring a material to be inspected according to the present invention, the outer peripheral surface of the material to be inspected that is coated with a paint is imaged with a camera. Imaging with the camera can be performed by, for example, the camera 32 provided in the measurement apparatus 30 shown in FIG. From the viewpoint of simplifying the processing in the subsequent processing using the captured image, the image is captured by the camera so that the vertical or horizontal center position of the captured image is the center of the outer peripheral surface of the inspection object. Is preferred.

  In the method for measuring a material to be inspected according to the present invention, the coordinates of the paint applied in the form of dots are detected from the captured image. Further, the coordinates of the detected spot-like coating paint are corrected so as to indicate the distance in a state where the outer peripheral surface of the inspection object is developed on a plane. At least one of a feed pitch, an axial speed, and a circumferential speed is calculated using the corrected coordinates of the dot-shaped coating material. As for the coordinate detection, correction of coordinates, and calculation of the feed pitch and the like of these dot-like coating paints, specific processing contents and preferable modes will be described later.

  In such a method for measuring an inspection material of the present invention, the inspection material conveyed by the camera 32 is imaged over the entire length at a predetermined time interval, and coordinate detection of the dotted coating paint is performed from the captured image. By correcting the coordinates and calculating the feed pitch and the like using the corrected coordinates, the feed pitch and the like can be measured over the entire length.

[Detection of coordinates of dotted paint]
As described above, the measuring device for a material to be inspected according to the present invention detects the coordinates of the paint applied in the form of dots from the image captured by the detecting means. Moreover, the measuring method of the to-be-inspected material of this invention detects the coordinate of the coating material apply | coated to the dot shape from the imaged image. The coordinate detection of these dot-like coating paints is performed by, for example, performing a process of identifying the outer peripheral surface of the material to be inspected and the dot-like coating paints on the captured image, and then detecting the identified dot-like coating paints. This can be realized by performing processing for obtaining coordinates for the region.

  The process of discriminating between the outer peripheral surface of the material to be inspected and the dotted application paint from the captured image can be performed by binarization based on hue and brightness. The binarization standard can be set according to the properties of the outer peripheral surface of the material to be inspected and the paint. Thereby, it is possible to identify a plurality of dot-like coating paints present in the captured image.

  Further, in the process of obtaining the coordinates for the identified dot-like coating paint, for example, the center of gravity can be obtained for the area of the dot-like coating paint, and the coordinates of the center of gravity can be used as the coordinates of the dot-like coating paint. Since there are a plurality of dot-like coating paints in the captured image, a point cloud can be obtained by obtaining coordinates for each dot-like coating paint. The coordinates of the spot-like coating paint detected in this way are converted from [pixel] to [mm] as appropriate.

[Coordinate correction]
As described above, the inspection material measuring apparatus according to the present invention corrects the coordinates of the dotted application paint detected by the correcting means so as to indicate the distance in a state where the outer peripheral surface of the inspection material is developed on a plane. . Moreover, the measuring method of the to-be-inspected material of this invention correct | amends the coordinate of the detected spot-like coating paint so that it may show the distance in the state which expand | deployed the outer peripheral surface of the to-be-inspected material to the plane.

These corrections are performed for the following reasons.
(1) Although the image picked up by the camera is two-dimensional, the actual point-like coating paint is distributed three-dimensionally because it is distributed on the outer peripheral surface of the material to be inspected having a curvature. This is because the curvature (radius) of the outer peripheral surface of the material to be inspected is taken into consideration.
(2) If the outer peripheral surface is developed into a flat surface, the point-like coating paint is distributed in a straight line, and therefore linear approximation can be used for calculating the feed pitch. Further, if the outer peripheral surface is developed into a flat surface, the circumferential speed can be calculated.

  A process for correcting the detected coordinates of the dotted application paint so as to indicate the distance in a state where the outer peripheral surface is developed in a plane will be described with reference to FIG.

  2A and 2B are schematic diagrams for explaining the correction processing of the present invention. FIG. 2A is a front view and FIG. 2B is a side view. In the same figure, the pipe | tube 10 which is a to-be-inspected material, and the camera 32 which images the outer peripheral surface of the pipe | tube are shown. Since the center position of the captured image is the center of the outer peripheral surface of the material to be inspected, the camera 32 is arranged so that the axis of the tube 10 is positioned directly below the camera 32 as shown in FIG. Yes.

  The figure shows an xy coordinate system set for a captured image. In the xy coordinates, the position directly below the camera 32 (the center position of the captured image) is the origin (see the black circle in the figure), the longitudinal direction of the tube is the x axis, and the circumferential direction is the y axis. Further, in the figure, the position of the dotted application paint 51 detected from the captured image is indicated by a cross, and the coordinates of the dotted application paint 51 in the xy coordinate system are (a, b). . Here, the unit of coordinates (a, b) is mm. In the same figure, the position of the dot-shaped coating material 52 (actual dot-shaped coating material position) on the outer peripheral surface of the inspection object corresponding to the dot-shaped coating material 51 detected from the image is indicated by a cross. Show.

  On the other hand, the x′y ′ coordinate system (not shown) is a coordinate system in a state where the outer peripheral surface is developed on a plane. In the x′y ′ coordinate system, the position directly below the camera 32 (the center position of the captured image) is the origin, the longitudinal direction of the tube is the x ′ axis, and the circumferential direction is the y ′ axis. The coordinates of the actual dot-shaped coating material 52 in the x′y ′ coordinate system are (c, d). Here, the unit of the coordinates (c, d) is mm. Moreover, d shown in the figure means not the linear distance from the origin but the distance along the outer peripheral surface of the material to be inspected, in other words, the arc length.

The coordinates (c, d) of the actual punctiform coating paint 52 in the x′y ′ coordinate system are the following (3) using the detected coordinates (a, b) of the punctiform coating paint 51 in the xy coordinate system. ) And (4).
c = (a / L) × {L + r × (1-cos θ)} (3)
d = r × θ (4)
Here, r is the radius (mm) of the outer peripheral surface of the tube (inspected material) 10, L is the distance (mm) from the camera 32 to the outer peripheral surface of the tube (inspected material) 10, and θ is the tube (inspected). This is an angle (rad) formed by a straight line connecting the axis of the (material) 10 and the origin of the xy coordinate system and a straight line connecting the axis of the pipe (inspected material) 10 and the actual dot-shaped coating material 52. The above θ can be calculated by the following equation (5).

  In this way, the coordinates (c, d) of the x′y ′ coordinate system are obtained using the above equations (3) to (5), and the obtained coordinates (c, d) are set as the coordinates of the dotted coating paint. This makes it possible to correct the detected coordinates of the dotted application paint so as to indicate the distance in a state where the outer peripheral surface of the inspection object is developed on a plane. This correction is performed for each point-like coating material constituting the point group.

[Calculation of feed pitch, etc.]
As described above, the measuring apparatus for a material to be inspected according to the present invention calculates the feed pitch and the like by using the corrected coordinates of the dotted application paint by the calculating means. Moreover, the measuring method of the to-be-inspected material of this invention calculates a feed pitch etc. using the coordinate of the corrected point-like coating paint. These processes will be described with reference to FIG.

  FIG. 3 is a schematic diagram showing the distribution of the corrected point-like coating paint. The x′y ′ coordinate system in the figure is a coordinate system in a state where the outer peripheral surface is developed on a plane. In the x′y ′ coordinate system, the center position of the captured image is the origin, the longitudinal direction of the tube is the x ′ axis, and the circumferential direction is the y ′ axis. The axis of the outer peripheral surface of the flaw detection material is located on the x ′ axis. In the figure, the corrected dot-like coating material 60 is indicated by a cross. In order to facilitate understanding of the distribution of the dotted coating paint 60, the outline 61 of the outer peripheral surface of the tube is indicated by a two-dot chain line, and the region 62 of the image is indicated by a dotted line.

  When calculating the feed pitch, the axial speed, and the circumferential speed, a first group of dot-like coating materials distributed in a predetermined axial direction (x′-axis direction) range is extracted. Thereby, the point group of the dot-shaped coating material distributed linearly is extracted from the point group comprised by the point-shaped coating material detected and corrected.

  When calculating the feed pitch, in addition to extracting the first group, a second group made of dotted application paints adjacent to the first group and distributed in a predetermined axial range is extracted. . This is because the axial distance between the point group of the dot-like coating material distributed in a straight line and the point group of the dot-like coating material distributed in a straight line adjacent thereto is the feed pitch. Such a process of extracting the first group and the second group can be performed by the following procedure A, for example.

(Procedure A)
(1) The point group composed of the detected point-corrected coating materials is rearranged in ascending order based on the x ′ coordinate value.
(2) Extract a point group of punctiform coating paints whose x ′ coordinate values are distributed in a predetermined range.
(3) Average the x ′ coordinate values of the extracted point groups, and obtain the absolute value of the average.
(4) Among the point groups, the point group having the smallest average absolute value of the x ′ coordinates is defined as a first group 63, and the point group having the second smallest absolute value of the average x ′ coordinates is defined as the second group 64. And

  The predetermined range when extracting the point group of the punctiform coating material whose x ′ coordinate value is distributed in the predetermined range is the feed pitch (or the axial speed of the material to be inspected) or the size of the image captured by the camera. What is necessary is just to set according to it.

  More specifically, the process of extracting the point group of the dot-like coating material in which the x ′ coordinate value is distributed in a predetermined axial range can be performed by repeating the following procedure B. The threshold value in the following procedure B may be set according to the time interval for applying the paint and the circumferential speed of the material to be inspected spirally. Further, m is a variable indicating the index number of the dot-like coating material, and is incremented by 1 up to the number of point-like coating materials belonging to the point group constituted by the point-like coating material detected and corrected from 2. The following procedure B is performed.

(Procedure B)
(1) An absolute value is obtained for the difference between the y ′ coordinate value of the m-1th point-like coating paint and the y ′ coordinate value of the mth point-like coating paint.
(2) When the absolute value of the difference is less than the threshold value, the m-th point application paint is made the same point group as the m-th point application paint, and the absolute value of the difference exceeds the threshold value The mth point-like coating paint is a new point group.

  The feed pitch can be calculated using the first group 63 and the second group 64 extracted in the procedure A described above. As shown in the figure, a first approximate straight line 65 is obtained from the first group 63 and a second approximate straight line 66 is obtained from the second group 64, and the axial directions of the first approximate straight line 65 and the second approximate straight line 66 are obtained. The distance (in the x′-axis direction) can be used as the feed pitch. More specifically, the distance (mm) between the first approximate line 65 and the second approximate line 66 is x ′ = a1 × y ′ + b1 for the first approximate line 65 and x ′ = a2 for the second approximate line 66. When xy ′ + b2, it can be | b2-b1 |. The first approximate line 65 and the second approximate line 66 can be obtained by, for example, the least square method.

  In addition, an average value av1 is obtained for the x ′ coordinate value of the first group, an average value av2 is obtained for the x ′ coordinate value of the second group, and | av1−av2 | that is an absolute value of the difference is set as the feed pitch. You can also.

The axial speed can be calculated using the first group of dot-like coating materials distributed in a predetermined axial direction (x′-axis direction) range. Two points belonging to the first group are selected, and the axial velocity VA (mm / sec) can be calculated by the following equation (1).
VA = DA / {(N + 1) TP} (1)
Here, DA is the distance (mm) between the two selected points in the axial direction (x′-axis direction), N is the number of points existing between the two selected points, and TP is the time for applying the paint in a dot shape. Interval (seconds).

  Since the processing to calculate the axial speed tends to cause errors in the coordinates of the dotted coating paint due to the curvature of the outer peripheral surface as the distance from the axis of the outer peripheral surface of the flaw detection material increases, C is preferred. As a result, it is possible to calculate the axial speed by selecting a dot-like coating material positioned around the axis of the outer peripheral surface of the flaw detection material from among the dot-like coating materials. The following procedure C uses the first group extracted by the procedure A for extracting the first group 63 and the second group 64 described above. L in the procedure C is a natural number, and may be set according to the time interval for applying the paint in a dot shape, the circumferential speed of the material to be inspected spirally, and the size of the image captured by the camera.

(Procedure C)
(1) A point-shaped coating paint belonging to the first group and having a y ′ coordinate value of 0 or more is selected as the l-th (for example, third) point-shaped coating paint close to the y ′ axis. Then, the x ′ coordinate value e of the selected dot-like coating material is obtained.
(2) x 'of the point-like coating paint belonging to the first group and having the y' coordinate value of less than 0 and the l-th (for example, third) point-like coating paint close to the y 'axis The coordinate value f is acquired.
(3) With DA = | e−f | and N = 2 × l−1, the axial velocity VA (mm / second) is calculated by the above equation (1).

The circumferential speed can be calculated using the first group of dot-like coating paints distributed in a predetermined axial direction (x′-axis direction) range. Two points belonging to the point group are selected, and the circumferential velocity VC (mm / sec) can be calculated by the following equation (2).
VC = DC / {(N + 1) TP} (2)
Here, DC is the distance (mm) between the two selected points in the circumferential direction (y′-axis direction), N is the number of points existing between the two selected points, and TP is the time for applying the paint in the form of dots. Interval (seconds).

  Since the processing to calculate the circumferential speed tends to cause errors in the coordinates of the dotted coating paint due to the curvature of the outer peripheral surface as it goes away from the axis of the outer peripheral surface of the flaw detection material, the following procedure D is preferred. As a result, it is possible to calculate the axial speed by selecting a dot-like coating material positioned around the axis of the outer peripheral surface of the flaw detection material from among the dot-like coating materials. The following procedure D uses the first group extracted by the procedure A for extracting the first group 63 and the second group 64 described above. “O” in the procedure D is a natural number, and may be set according to the time interval at which the paint is applied in the form of dots, the circumferential speed of the material to be inspected spirally, and the size of the image captured by the camera.

(Procedure D)
(1) Of the punctiform paints belonging to the first group and having a y ′ coordinate value of 0 or more, a punctiform paint paint close to the y ′ axis is selected as the o-th (for example, the third). Then, the y ′ coordinate value g of the selected dot-like coating material is obtained.
(2) y ′ of the dot-like coating paint belonging to the first group and having the y ′ coordinate value of less than 0 is the o-th (for example, third) point-like coating paint close to the y ′ axis. The coordinate value h is acquired.
(3) DC = | g−h |, N = 2 × o−1, and the circumferential speed VC (mm / second) is calculated by the above equation (2).

  In this way, the measuring apparatus and measuring method for a material to be inspected according to the present invention can measure a feed pitch, an axial speed, and a circumferential speed. According to the present invention, if the flaw detection pitch is grasped over the entire length by measuring the feed pitch of the flaw detection material being spirally conveyed in the non-destructive inspection, the occurrence of the uninspected area and the excessive overlapping inspection area The occurrence can be detected. Therefore, the present invention can prevent the outflow of defective products by detecting the occurrence of an uninspected area. In addition, the present invention can improve inspection efficiency by re-adjusting and optimizing the conditions of spiral conveyance when an uninspected area occurs or when an excessive overlapping inspection area occurs.

  By measuring the axial speed of the material to be inspected spirally using the present invention over the entire length, and adjusting the conditions of spiral conveyance again according to the result, the axial direction of the material to be inspected The speed can be made uniform over the entire length. As a result, the process of detecting the leading edge of the material to be inspected spirally by the edge detection sensor and starting the flaw detection by the flaw detection sensor after a predetermined time has passed since the detection has been optimized, and the uninspected area Can be prevented from occurring. Similarly, the end detection sensor detects the tail end of the material to be inspected spirally, and the processing for ending the flaw detection by the flaw detection sensor after a predetermined time has passed since the detection has been optimized. Can be prevented from occurring.

  Further, according to the present invention, it is possible to measure the feed pitch, the axial speed, and the circumferential speed, and input the measurement results to the spiral conveyance device to perform feedback control. For example, the measurement results of feed pitch, axial speed, and circumferential speed are compared with the target values set in the spiral transport device, and the skew angle and skew roller rotation speed are adjusted according to the difference, and the feed pitch and shaft The directional speed and circumferential speed are controlled to target values. Thereby, the feed pitch of spiral conveyance in the nondestructive inspection can be made uniform, and the flaw detection pitch can be made uniform over the entire length.

  In the present invention, the coating material is applied to the outer peripheral surface of the material to be inspected in a dotted manner at regular time intervals, and the outer peripheral surface on which the coating material is applied in a dotted manner is imaged with a camera, thereby providing a conventional feed. Compared with the pitch measurement method, the measurement accuracy of the feed pitch and the like can be improved. In addition, since the coating of the paint is applied at regular intervals and the outer peripheral surface is imaged by the camera without using the data of the motor speed detection encoder, etc., an error due to roller slipping or the like occurs in the measurement result. Absent. This also improves the measurement accuracy such as the feed pitch.

  Tests for measuring the feed pitch and the like were performed on the pipes spirally transported in the non-destructive inspection by the measuring apparatus and measuring method for the inspected material of the present invention, and the effects of the present invention were verified.

[Test method]
In this test, the measurement apparatus for the material to be inspected shown in FIG. 1 was used. The pipe of the material to be inspected was made of material SUS304, outer diameter 114.3 mm, wall thickness 8.2 mm, and length 11000 mm. The tube was spirally conveyed by a skew roller.

  When applying the spot-like paint on the outer peripheral surface of the tube at a constant time interval by the applicator, the water-based paint was applied in a circular shape at 1/120 second intervals. When the outer peripheral surface to which the paint is applied is imaged by the camera, the camera is arranged and imaged so that the axis of the tube is at the center position in the vertical direction of the image to be imaged. Imaging of images with the camera was performed over the entire length of the transported tube, and a total of 1980 images were captured.

  The captured images are sequentially received by a personal computer, a threshold is set so that the outer peripheral surface of the tube and the dotted coating can be clearly distinguished, and the dotted coating is obtained by binarization based on the hue. Identified. A point cloud was obtained by determining the center of gravity of the region for all identified point-like coating paints and using the coordinates of the center of gravity as the coordinates of the point-like coating paints. Further, the coordinates of the detected spot-like coating paint were converted from [pixel] to [mm].

  The correction of the coordinates was performed by the equations (3) to (5). This correction was performed for all the point-like coating paints constituting the point group. Here, the distance L from the camera to the outer peripheral surface of the tube was about 500 mm.

  By the above-described procedure A and procedure B, a point group of the point-like coating paint in which the x ′ coordinate value is distributed in a predetermined range is extracted from the point group, and the average of the x ′ coordinates is extracted from the extracted point group. The point group having the smallest absolute value was defined as the first group, and the point group having the second smallest absolute value of the average of x ′ coordinates was defined as the second group.

  In calculating the feed pitch, the first approximate line (x ′ = a1 × y ′ + b1) was obtained from the first group, and the second approximate line (x ′ = a2 × y ′ + b2) was obtained from the second group. . The first approximate straight line and the second approximate straight line were obtained by the method of least squares. And | b2-b1 | was defined as the axial distance between the first approximate line and the second approximate line, and the distance was defined as the feed pitch.

  Further, the axial speed was calculated by the above-described procedure C, and at that time, l = 3. The circumferential speed was calculated by the procedure D described above, and o = 3 at that time.

  For comparison, in this test, a marker (pen) fixed in a state perpendicular to the outer peripheral surface was brought into contact with a spirally conveyed tube and a line was drawn. After the spiral conveyance, the feed pitch was measured by measuring the line spacing by the marker at the location where the image was taken.

  In this test, the touch roller provided in the peripheral speed meter was pressed against the outer peripheral surface of the spirally conveyed tube. When the camera picked up an image, the peripheral speed measured by the peripheral speed meter (hereinafter also referred to as “flaw detection speed”) was recorded.

The flaw detection speed (mm / second) measured by the peripheral speed meter is a speed obtained by combining the axial speed and the peripheral speed. For this reason, the flaw detection speed V (mm / second) was calculated by the following equation (6) using the axial speed VA (mm / second) and the circumferential speed VC (mm / second) measured according to the present invention: V = ( VA ² + VC ² ) ^1/2 (6)

[Test results]
When the feed pitch measured according to the present invention was compared with the feed pitch measured using a marker line over the entire length of the tube, the error was 5% or less. Moreover, when the flaw detection speed calculated from the axial speed and the circumferential speed measured according to the present invention and the flaw detection speed measured by the peripheral speed meter were compared over the entire length of the tube, the error was 5% or less. there were. For this reason, it became clear that the feed pitch, the axial speed, and the circumferential speed can be measured over the entire length of the transported pipe by the measuring apparatus and measuring method for the material to be inspected according to the present invention.

  The measuring apparatus and measuring method for a material to be inspected of the present invention can measure the feed pitch (flaw detection pitch), the axial speed, and the circumferential speed over the entire length of the material to be inspected spirally in nondestructive inspection. For this reason, if this invention is applied to the flaw inspection by the ultrasonic flaw detection in the production line of a steel pipe, it can contribute to quality improvement by suppressing generation | occurrence | production of an uninspected area | region. Moreover, it can contribute to the improvement of manufacturing efficiency by suppressing that an overlap inspection area | region becomes excessive.

10: tube, 10a: center of the outer peripheral surface of the tube, 11: dot-like coating paint,
20: Skew roller, 30: Measuring device for the flaw detection material, 31: Coating device,
32: Camera, 32a: Center of camera, 40: Personal computer,
41: main body, 42: monitor, 51: dot-like coating paint detected from the image,
52: Actual punctiform coating paint, 60: Corrected punctiform coating paint,
61: Outline of outer peripheral surface of material to be inspected, 62: Image area,
63: A first group of dotted application paints, 64: A second group of dot application paints,
65: approximate straight line of the first group, 66: approximate straight line of the second group, 70: flaw detection sensor

Claims (8)

In non-destructive inspection, an apparatus for measuring at least one of a feed pitch, an axial speed, and a circumferential speed for an inspection object conveyed in the axial direction while rotating around an axis,
An applicator for applying paint in a dotted manner to the outer peripheral surface of the material to be inspected at regular time intervals;
A camera that images the outer peripheral surface of the material to be inspected that is coated with paint in the form of dots;
Detection means for detecting the coordinates of the paint applied in the form of dots from the captured image;
Correction means for correcting the coordinates of the detected spot-like coating paint so as to indicate the distance in a state where the outer peripheral surface of the inspection object is developed on a plane;
A measuring apparatus for a material to be inspected, comprising: a calculating unit that calculates at least one of a feed pitch, an axial speed, and a circumferential speed by using the corrected coordinates of a dotted coating material.   The calculation means extracts a first group of dotted application paints distributed in a predetermined axial range, and is adjacent to the first group and distributed in a predetermined axial range. The second group of coating paints is extracted, and the axial distance between the approximate straight line obtained from the first group and the approximate straight line obtained from the second group is used as the feed pitch. Inspection material measuring device.   The calculation means extracts a first group of dotted application paints distributed in a predetermined axial range, and is adjacent to the first group and distributed in a predetermined axial range. The second group of coating paints is extracted, and the axial distance between the approximate straight line obtained from the first group and the approximate straight line obtained from the second group is used as the feed pitch. Inspection material measuring device. The calculation means extracts a first group of point-like coating paints distributed in a predetermined axial range, selects two points belonging to the first group, and calculates a circumferential speed VC according to the following equation (2). The apparatus for measuring a material to be inspected according to claim 1, wherein (mm / second) is calculated.
VC = DC / {(N + 1) TP} (2)
Here, DC is the circumferential distance (mm) between the two selected points, N is the number of points existing between the two selected points, and TP is the time interval (seconds) at which the paint is applied in the form of dots. . In non-destructive inspection, a method for measuring at least one of a feed pitch, an axial speed, and a circumferential speed for an inspection object conveyed in the axial direction while rotating around an axis,
Applying the paint in a dotted manner at regular intervals to the outer peripheral surface of the material to be inspected;
Imaging the outer peripheral surface of the material to be inspected to which the paint is applied in the form of dots with a camera;
Detecting the coordinates of the paint applied in the form of dots from the captured image;
Correcting the detected point-like coating paint coordinates so as to indicate the distance in a state where the outer peripheral surface of the material to be inspected is developed on a plane;
And a step of calculating at least one of a feed pitch, an axial speed, and a circumferential speed by using the corrected coordinates of the dot-shaped coating material.   When calculating the feed pitch using the coordinates of the corrected dot-shaped coating material, a first group of dot-shaped coating materials distributed in a predetermined axial range is extracted, and the first group is extracted. A second group of dot-like coating paints adjacent to the group and distributed in a predetermined axial range is extracted, and the approximate straight line obtained from the first group and the approximate straight line obtained from the second group are axial directions 6. The method for measuring a material to be inspected according to claim 5, wherein the feed pitch is calculated by calculating a distance. When the axial velocity is calculated using the corrected coordinates of the dotted application paint, a first group consisting of the dotted application paint distributed in a predetermined axial range is extracted, and the first group is extracted. 6. The method for measuring a material to be inspected according to claim 5, wherein two points belonging to the above are selected and the axial velocity VA (mm / second) is calculated by the following equation (1).
VA = DA / {(N + 1) TP} (1)
Here, DA is the axial distance (mm) between the two selected points, N is the number of points existing between the two selected points, and TP is the time interval (seconds) at which the paint is applied in the form of dots. . When calculating the circumferential speed using the corrected coordinates of the dot-like coating material, a first group of dot-like coating materials distributed in a predetermined axial range is extracted, and the first group is extracted. 6. The method for measuring a material to be inspected according to claim 5, wherein two points belonging to the above are selected and the circumferential velocity VC (mm / second) is calculated by the following equation (2).
VC = DC / {(N + 1) TP} (2)
Here, DC is the circumferential distance (mm) between the two selected points, N is the number of points existing between the two selected points, and TP is the time interval (seconds) at which the paint is applied in the form of dots. .

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