JP2004279045A - Magnetic particle inspection device of magnetic pipe and manufacturing method of magnetic pipe - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic particle inspection device of a magnetic pipe capable of performing accurately magnetic particle inspection of the pipe inner surface, even to a magnetic pipe having a small pipe diameter (especially, a magnetic pipe having the pipe diameter below 500 mm). <P>SOLUTION: A magnetizer 4 loaded on a truck 1 for running inside the pipe, for magnetizing an inspection part on the pipe inner surface is equipped with a yoke 6 having a pair of yoke arm parts 6b, 6b having the tip bent downward. A CCD camera 9 for photographing magnetic particles scattered on the inspection part is arranged between the pair of yoke arm parts 6b, 6b. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a magnetic tube magnetic particle flaw detector for non-destructively inspecting the inner surface of a magnetic tube such as a steel tube (hereinafter referred to as a magnetic tube) and a method for manufacturing a magnetic tube using the same.
[0002]
[Prior art]
As a method of nondestructively inspecting a defect of a magnetic substance such as iron, a magnetic particle flaw detection method is known. The magnetic particle flaw detection method is a flaw detection method in which a subject is magnetized by a magnetizer as described in JIS G0565, magnetic powder is sprayed on the magnetized subject surface, and a defect is detected from a magnetic powder pattern formed on the subject surface. .
[0003]
As a method of magnetizing the subject, a two-pole system in which the subject is magnetized by a pair of magnetic poles (two poles in total) and two pairs of magnetic poles (four poles in total) are used to rotate the direction of the combined magnetic field. There is a quadrupole rotating magnetic field type.
[0004]
However, in any of the conventional magnetic particle flaw detection methods, it is necessary for an operator to directly observe and determine a magnetic particle pattern, which causes problems in workability and inspection accuracy.
[0005]
Therefore, in order to improve workability and inspection accuracy, a quadrupole rotating magnetic field type magnetic particle flaw detector that observes a magnetic particle pattern formed on the surface of a flat object using a CCD camera has been proposed. It is considered (for example, Patent Document 1).
[0006]
[Patent Document 1]
Japanese Patent No. 2733185
[Problems to be solved by the invention]
When inspecting the inner surface of a magnetic tube such as a steel tube with magnetic particles, it is necessary to provide a space for the operator observing the magnetic powder pattern to enter the tube. I couldn't do that.
[0008]
Further, even if an attempt is made to use the magnetic particle flaw detection device described in Patent Document 1 for observing a magnetic powder pattern with a CCD camera for magnetic particle flaw detection on the inner surface of a magnetic tube, the magnetic particle flaw detection device described in Patent Document 1 only requires a flat plate-shaped subject. Since the size of the device is not particularly taken into consideration, a magnetic tube having a small tube diameter (particularly, a tube having a diameter of 500 mm or less due to the size of the magnetizer or the yoke of the magnetizer) is not considered. (Magnetic tube), the magnetic particle flaw detector could not enter the magnetic tube, and could not perform magnetic particle flaw detection on the inner surface of the tube. Although the above-mentioned Patent Document 1 is a magnetic particle inspection device of a quadrupole rotating magnetic field type, the situation is the same even for a magnetic particle inspection device of a two-pole type.
[0009]
The present invention has been made in view of the above situation, and is capable of accurately performing magnetic particle flaw detection on the inner surface of a magnetic tube having a small tube diameter (particularly, a magnetic tube having a tube diameter of 500 mm or less). It is an object of the present invention to provide a magnetic particle flaw detector for a magnetic tube that can be used. Still another object of the present invention is to provide a method of manufacturing a magnetic tube capable of obtaining good quality by using the magnetic particle flaw detector.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, the present invention has the following features.
[0011]
[1] A magnetic particle flaw detector for a magnetic tube, comprising: a truck for traveling on the inner surface of the magnetic tube; and (a) to (d) below mounted on the truck.
(A) A linear yoke body extending in a horizontal direction, and a pair of yoke arms extending from both ends of the yoke body in a horizontal direction orthogonal to a direction in which the yoke body extends and having a tip bent downward. A magnetizer having a yoke for magnetizing the part to be inspected; (b) a magnetic powder disperser for dispersing magnetic powder on the part to be inspected; and (c) a light (d) for irradiating the magnetic powder dispersed on the part to be inspected. A) A camera for photographing magnetic particles sprayed on the inspected part [2] A two-pole magnetic particle flaw detector, wherein the camera is installed between a pair of yoke arms. The magnetic particle flaw detector for a magnetic tube according to [1].
[0012]
[3] A four-pole rotating magnetic field type magnetic particle flaw detector, in which a pair of magnetizers are installed such that a pair of yoke arms face each other, and the four yoke arms of the pair of magnetizers are substantially the same. The magnetic particle flaw detector for a magnetic tube according to [1], wherein the camera is installed at a central portion.
[0013]
[4] The light according to any of [1] to [3], wherein the light is installed at a position where specularly reflected light of the irradiation light directed toward the inspected portion on the inner surface of the tube does not enter the camera. A magnetic particle flaw detector for a magnetic tube according to any one of the above.
[0014]
[5] The magnetic particle flaw detector for a magnetic tube according to any one of [1] to [4], wherein the body of the bogie is made of a non-magnetic and flexible material.
[0015]
[6] A method for manufacturing a magnetic tube, comprising: a tube forming step of forming a tube; and an inspection step of inspecting the formed tube, wherein in the inspection step, any one of the above [1] to [5]. A method for manufacturing a magnetic tube, comprising: inspecting an inner surface of the magnetic tube using the magnetic particle flaw detector for a magnetic tube.
[0016]
Note that the present invention includes those having the following features.
[0017]
[7] The magnetic particle flaw detector for a magnetic tube according to any one of [1] to [5], wherein a mandrel for operating the traveling of the cart is attached to the cart.
[0018]
[8] The magnetic particle flaw detector for a magnetic tube according to the above [7], wherein the mandrel is provided with a distance scale for measuring a distance from a tube end of the magnetic tube to a portion to be inspected.
[0019]
[9] The yoke arm of the magnetizer and the wheels of the bogie are arranged on the same line in the running direction of the bogie, [1] to [5] and [7] or [8]. 3. A magnetic particle flaw detector for a magnetic tube according to claim 1.
[0020]
[10] The magnetic tube according to any one of [1] to [5] and [7] to [9], wherein a visible light lamp for irradiating an inner surface of the tube is mounted on the carriage. Magnetic particle flaw detector.
[0021]
[11] A method for manufacturing a magnetic tube, comprising: a tube forming step of forming a tube; and an inspection step of inspecting the formed tube, wherein in the inspection step, any one of the above [7] to [10]. A method for manufacturing a magnetic tube, comprising: inspecting an inner surface of the magnetic tube using the magnetic particle flaw detector for a magnetic tube.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
The present inventors have conducted various studies to reduce the size of the magnetic particle flaw detection apparatus to a size that can be accommodated in the magnetic tube to be flaw-detected. I thought about bending.
[0023]
However, when the yoke of the magnetizer is bent in this manner, there is a concern that the magnetic path changes and the magnetic field distribution at the tip of the yoke changes. In addition, since the yoke becomes longer, the magnetic path becomes longer, and there is a concern that the magnetic field at the tip of the yoke decreases.
[0024]
Actually, in magnetizers used for magnetic particle flaw detection and leakage magnetic flux flaw detection, there is almost no use of bending the yoke in this way, and as a technician measuring using a magnetic field, bending the yoke in this way That is an act of strong concern.
[0025]
However, in order to achieve the required high-precision flaw detection of the inner surface of the magnetic tube, it is very necessary to downsize the flaw detection apparatus.
[0026]
Actually, magnetizing the magnetic tube using a magnetizer in which the tip of a U-shaped yoke is bent into an L-shape and measuring the magnetic field distribution shows that the magnetic field is within 5% of that before bending the yoke. The results were better than the initial concerns. This is because when the yoke is bent in an L-shape, the change in the magnetic path does not affect the measurement result, and since the magnetic tube to be measured is a ferromagnetic material, the magnetic path becomes longer. It is probable that the impact was small.
[0027]
From the results of these studies, we found that the magnet tube could be magnetized properly even when the yoke of the magnetizer was bent. The present invention has made it possible to carry out magnetic particle flaw detection with high precision.
[0028]
FIG. 1 shows a magnetic particle flaw detector according to one embodiment of the present invention. FIG. 1A is a side view, and FIG. 1B is a view taken along the line AA in FIG. 1A.
[0029]
The magnetic particle flaw detector according to one embodiment of the present invention is a two-pole type magnetic particle flaw detector, and includes a cart 1 for traveling on the inner surface of a magnetic tube to be inspected, and an inner surface of the tube mounted on the bogie 1. A magnetizer 4 for magnetizing the inspection unit, a magnetic powder disperser 7 for spraying the fluorescent magnetic powder to the inspection target, a black light 3 for irradiating the fluorescent magnetic powder sprayed to the inspection target, and an inspection target A CCD camera 9 for photographing the fluorescent magnetic powder sprayed on the portion and a visible light lamp 11 for irradiating the inner surface of the tube are provided.
[0030]
The trolley 1 includes a pair of left and right front wheels 2 and a rear wheel 3, and a mandrel 10 at a rear portion of the trolley 1 for operating the traveling of the trolley 1.
[0031]
The detailed structure of the magnetic particle flaw detector according to this embodiment will be described below.
[0032]
(1) Regarding magnetizer.
[0033]
In the magnetic particle flaw detection apparatus according to this embodiment, the magnetizer 4 includes a yoke 6, a magnetized coil wound around the yoke 6, and a magnetized coil cover 5a for protecting the magnetized coil. Then, as shown in FIG. 2, as shown in a perspective view of the magnetizer 4 with the magnetized coil cover 5a removed, the yoke 6 includes a linear yoke body 6a extending in the horizontal direction and two ends of the yoke body 6a. It has a pair of yoke arms 6b, 6b that extend in the horizontal direction perpendicular to the direction in which the yoke trunk 6a extends and whose tips are bent vertically downward. The magnetizing coil 5 is wound around the yoke body 6a. The entire area where the magnetizing coil 5 is wound is covered with a magnetizing coil cover 5a.
[0034]
The effect of the magnetizer 4 having the above-described structure will be described with reference to FIG.
[0035]
FIGS. 3A and 3B show a conventional magnetizer 54 having a U-shaped yoke 56 in which a pair of linear yoke arms 56b extend from both ends of a linear yoke body. The magnetic particle flaw detector installed on the carriage 1 has a structure in which the magnetized coil cover 55a covering the magnetized coil and the yoke 56 extend in the vertical direction, and the overall height of the magnetizer 54 increases. The height of the entire device is also high.
[0036]
On the other hand, in the magnetic particle flaw detector according to this embodiment, as shown in FIG. 3C, since the yoke having the yoke arm portion 6b whose tip is bent is used, the height of the yoke 6 itself is low. At the same time, the magnetized coil cover 5a for covering the magnetized coil can be installed on the carriage 1, and the overall height of the magnetizer 4 is reduced, so that the overall height of the device is reduced and the device is compact.
[0037]
Thereby, it becomes possible to travel inside the tube even for a magnetic tube having a small tube diameter, and it is possible to perform magnetic particle flaw detection on the inner surface of the tube.
[0038]
(2) Camera arrangement.
[0039]
In the magnetic particle flaw detector according to this embodiment, as shown in FIG. 1, a CCD camera 9 is disposed between a pair of left and right yoke arms 6b, 6b.
[0040]
In order to accurately capture the magnetic powder pattern with a camera, the camera arrangement is important. The camera arrangement will be described with reference to FIG.
[0041]
First, as shown in FIG. 3A, a conventional U-shaped yoke 56 having a pair of linear yoke arms 56b is used, and the CCD camera 9 is turned obliquely. In the case where the inspection surface of the tube inner surface is arranged to be photographed from between the arms 56b, since the in-focus surface of the CCD camera 9 does not coincide with the inspection surface, the in-focus range becomes narrow, and the image is sharp. Difficult to obtain a good image.
[0042]
In order to make the focal plane of the CCD camera 9 coincide with the inner surface of the tube, as shown in FIG. 3B, when the CCD camera 9 is arranged vertically away from the yoke 56 at a position away from the yoke 56. Means that after magnetizing with the yoke 56, the device is moved to a position where the image can be captured by the CCD camera 9, and then the image is captured. At the time of capturing, the surface to be inspected is not magnetized, so that the magnetic powder flows and the magnetic powder flows. It is not possible to accurately capture patterns.
[0043]
On the other hand, in the magnetic particle flaw detector according to this embodiment, as shown in FIG. 3C, since the yoke 6 having the yoke arm portion 6b whose tip is bent is used, the pair of yoke arm portions 6b , 6b, the CCD camera 9 can be arranged vertically downward. As a result, it is possible to photograph the inspected surface in a magnetized state in a focused state, and it is possible to obtain a clear image of an accurate magnetic powder pattern.
[0044]
(3) About arrangement of black light.
[0045]
When performing normal image measurement, the light source and the observation device are placed at the specular reflection position with respect to the measurement target, specular reflection is performed in the normal part, and diffuse reflection is performed from the abnormal part where the normal part and surface normal are different. A method is used in which a normal part and an abnormal part are discriminated based on a difference in light amount between light and diffused light. However, in this method, the normal part is observed to be extremely bright and the abnormal part is observed to be dark. Therefore, when the operator visually confirms the observed image, an image that is significantly different from the case of direct visual observation, which has been conventionally performed, is obtained, and the operator is confused in discriminating a defect. Conversely, when fluorescent magnetic powder is used, the luminance of the abnormal portion where a large amount of magnetic powder gathers is increased by the emission of the fluorescent magnetic powder. Regardless of whether the contrast with the fluorescence at the abnormal portion is insufficient and the obtained image is visually checked by a person or automatically determined by image processing or the like, there is a problem that discrimination is difficult in any case.
[0046]
On the other hand, in the magnetic particle flaw detector according to the present embodiment, the black light 8 for emitting the fluorescent magnetic powder emits the specularly reflected light on the inner surface of the tube with respect to the irradiation light directed toward the inspection target by the camera of the CCD camera 9. It is arranged at a position that does not enter the lens 9a. For example, the position of the camera lens 9a is deviated from the regular reflection position of the black light 3 by about 5 degrees. As a result, an image having a contrast can be obtained even when the fluorescent magnetic powder is used, and an image captured by the CCD camera 9 can be made an image equivalent to that in the case of conventional direct viewing.
[0047]
(4) About the cart.
[0048]
In general, a non-magnetic, high-rigidity cart such as an aluminum cart is used as a cart so as to enable flaw detection with a constant distance between the mounted yoke and camera and the surface to be inspected. . However, if a highly rigid bogie is used, and the surface to be inspected has irregularities, if the wheels of the bogie ride on the irregularities, the distance between the yoke and the camera and the inspected surface cannot be kept constant.
[0049]
On the other hand, in the magnetic particle flaw detection apparatus according to this embodiment, the body of the carriage 1 is made of a non-magnetic and highly flexible material such as acrylic or bakelite. Thus, even when the surface to be inspected has irregularities, the body of the bogie 1 is warped by the attraction force of the magnetizer 4, and the distance between the yoke 6 and the CCD camera 9 and the surface to be inspected is kept constant.
[0050]
Further, by using a transparent material such as acrylic for the body of the carriage 1, the CCD camera 9 can photograph the surface to be inspected from above the carriage 1 without providing a camera window on the carriage 1.
[0051]
Further, since acrylic has the property of blocking ultraviolet light and transmitting visible light, it can function as a filter when flaw detection is performed using fluorescent magnetic powder, and can contribute to improvement in flaw detection accuracy.
[0052]
(5) About the operation of traveling of the bogie.
[0053]
In order to continuously detect the entire length of the tube to be inspected, a mechanism that runs in the axial direction of the tube is required. In a system in which an operator travels with a bogie as in the magnetic particle flaw detection device described in Patent Literature 1, since the operator cannot enter the pipe when the pipe diameter is small, it is necessary to properly fit the inspected part. It is difficult to move.
[0054]
On the other hand, in the magnetic particle flaw detector according to this embodiment, the mandrel 10 is attached to the rear part of the bogie 1, and an operator operates the bogie 1 with the mandrel 10 from outside the pipe to continuously extend the entire length in the pipe. To detect flaws.
[0055]
When the mandrel 10 is attached to the rear end of the bogie 1 as shown in a plan view in FIG. 4A and a side view in FIG. As a result, the bogie 1 swings vertically, and the movement in the tube axis direction becomes unstable. Therefore, as shown in a plan view in FIG. 4C and a side view in FIG. 4D, the mandrel 10 is mounted between the left and right rear wheels 3, 3, thereby suppressing the pitching of the bogie 1. Stable movement becomes possible.
[0056]
(6) Visible light.
[0057]
In a case where the butt weld on the inner surface of the welded steel pipe is continuously flaw-detected in the pipe axis direction, the bogie 1 is moved in the circumferential direction of the pipe while the mandrel 10 is operated and the bogie 1 is run as described above. May shift.
[0058]
Therefore, in the magnetic particle flaw detector according to this embodiment, a visible light 11 for irradiating the inner surface of the tube is mounted separately from the black light 8 for irradiating the fluorescent magnetic powder. By irradiating the inner surface of the tube with the visible light light 11 and operating the mandrel 8 while photographing the inner surface of the tube with the CCD camera 9, the circumferential displacement of the carriage 1 can be corrected.
[0059]
(7) The arrangement of the wheels and the yoke of the cart.
[0060]
In the inspection process of the magnetic tube, it may be necessary to continuously detect flaws in tubes having different diameters. At this time, when the distance between the yoke and the surface to be inspected changes, the detectability changes. Therefore, as shown in FIG. 5A, the front wheel 2 and the rear wheel 3 of the bogie 1 and the yoke arm 6b are connected to the bogie 1 If they are not on the same straight line when viewed from the running direction, it is necessary to adjust the distance between the surface to be inspected of the magnetic tube 20 and the yoke by changing the diameter of the front wheel 2 and the rear wheel 3. is there.
[0061]
On the other hand, as shown in FIG. 5B, by arranging the front wheel 2 and the rear wheel 3 of the bogie 1 and the yoke arm 6b on the same straight line when viewed from the running direction of the bogie 1, the pipe diameter is reduced. Even when flaw detection is performed on a different tube, the distance between the surface to be inspected of the magnetic tube 20 and the yoke 6 becomes constant, and measurement can be continuously performed without adjusting the distance between the surface to be inspected and the yoke 6.
[0062]
A procedure for performing magnetic particle flaw detection on a magnetic tube using the magnetic particle flaw detection apparatus configured as described above will be described with reference to FIG. FIG. 6A is a side view, and FIG. 6B is a view taken along the line AA in FIG. 6A. Here, a camera controller 12 that controls the CCD camera 9, a CRT 13 that displays an image captured by the CCD camera 9, and a magnetic powder supply device 14 that supplies magnetic powder to the magnetic powder spreader 7 are provided outside the welded steel pipe 21. It is provided in.
[0063]
{Circle around (1)} First, the welded steel pipe 21 is rotated so that the inner surface welded portion is located below.
[0064]
(2) Next, the trolley 1 is put into the welded steel pipe 21 and the trolley 1 is arranged at the flaw detection start position using the mandrel 10.
[0065]
(3) The magnetizer 4, the black light 8, and the CCD camera 9 are turned on by an external switch (not shown).
[0066]
(4) The mandrel 10 is operated to magnetize the portion to be inspected of the welded steel pipe 21 with the yoke 6 of the magnetizer 4 while the carriage 1 is running in the tube axis direction, and the magnetic particle disperser 7 applies fluorescence to the inspected portion. Sprinkle magnetic powder. At this time, every time the vehicle travels a predetermined distance, the power of the visible light lamp 11 is turned on, the inside of the welded steel pipe 21 is illuminated, and the inside of the welded steel pipe 21 is photographed by the CCD camera 9 to determine whether or not the inner surface welded portion is appropriately running. Check. In the case where the bogie 1 is displaced in the pipe circumferential direction from the inner welded portion, the carriage 1 can be returned to the inner welded portion by operating the carriage 1 using the mandrel 10 while checking the captured image. By attaching the tape measure 10a to the mandrel 10, the distance from the pipe end of the welded steel pipe 21 to the flaw detection position can be known.
[0067]
{Circle around (5)} The magnetic powder pattern formed by the fluorescent magnetic powder sprayed on the surface to be inspected is photographed by the CCD camera 9 and displayed on the CRT 13.
[0068]
(6) The presence or absence of a defect is determined from the image of the magnetic powder pattern displayed on the CRT 13. The defect may be determined by a method in which an operator visually checks the image of the magnetic powder pattern, or may be automatically determined by image processing or the like.
[0069]
As described above, the magnetic particle flaw detector according to this embodiment is configured to bend the arm of the yoke of the magnetizer and photograph the surface to be inspected with the CCD camera from the arm of the yoke. Since the height is reduced and the device is compact, flaw detection of a magnetic tube having a diameter of 180 mm to 500 mm, which has conventionally been difficult to detect, can be accurately performed. In particular, many laser welded pipes that have recently been used in many cases have a pipe diameter of 200 mm to 250 mm, and this magnetic particle flaw detection device can be more effectively utilized. Of course, it is needless to say that it can be used for flaw detection of a magnetic tube having a tube diameter larger than 500 mm.
[0070]
FIG. 6 shows a magnetic particle flaw detector according to another embodiment of the present invention. The magnetic particle flaw detector according to this embodiment is a four-pole rotating magnetic field type magnetic particle flaw detector. In this magnetic particle flaw detector, a pair of magnetizers 4, 4 are installed in the longitudinal direction of the carriage 1, and a pair of yoke arms 6b, 6b are arranged to face each other. It is different from the above-described two-pole type magnetic particle flaw detector in that it is installed at the center of the individual arm portions 6b, but the other structure is the same as the two-pole type magnetic particle flaw detector. .
[0071]
Therefore, also in this magnetic particle flaw detection apparatus, the height of the entire apparatus is low and the apparatus is compact as in the case of the above-described two-pole type magnetic particle flaw detection apparatus. Flaw detection of a magnetic tube of 180 mm to 500 mm can be performed with high accuracy.
[0072]
Further, in a magnetic tube production line having a tube forming step of forming a tube and an inspection step of inspecting the formed tube, in the inspection step, inspection is performed by using the magnetic particle flaw detector according to the embodiment of the present invention. It is possible to manufacture a magnetic tube of good quality.
[0073]
【The invention's effect】
Since the magnetic particle flaw detection device of the present invention uses a magnetizer having a yoke in which the tip of the yoke arm is bent downward, the height of the entire device can be reduced and the device is compact. It is possible to accurately detect a flaw in a magnetic tube having a small diameter, which has been difficult.
[0074]
Further, by using the magnetic particle flaw detector of the present invention in an inspection process in a magnetic tube production line, it is possible to produce a magnetic tube of good quality.
[Brief description of the drawings]
FIG. 1 is a diagram showing a magnetic particle flaw detector according to an embodiment of the present invention.
FIG. 2 is a perspective view of a magnetizer in the magnetic particle flaw detector according to one embodiment of the present invention.
FIG. 3 is an explanatory diagram regarding an arrangement of a yoke and a camera according to an embodiment of the present invention.
FIG. 4 is an explanatory diagram relating to a mounting position of a mandrel in one embodiment of the present invention.
FIG. 5 is an explanatory diagram regarding an arrangement of a yoke and wheels according to an embodiment of the present invention.
FIG. 6 is an explanatory diagram of a flaw detection method using the magnetic particle flaw detection apparatus according to one embodiment of the present invention.
FIG. 7 is a diagram showing a magnetic particle flaw detector according to another embodiment of the present invention.
[Explanation of symbols]
Reference Signs List 1 cart 2 front wheel 3 rear wheel 4 magnetizer 5 magnetizing coil 5a magnetizing coil cover 6 yoke 6a yoke trunk 6b yoke arm 7 magnetic powder spreader 8 black light 9 CCD camera 9a camera lens 10 mandrel 11 visible light lamp 12 camera controller 13 CRT
14 Magnetic powder feeder 20 Magnetic tube 21 Welded steel tube

Claims (6)

A magnetic particle flaw detector for a magnetic tube, comprising: a carriage for traveling on the inner surface of the magnetic tube; and (a) to (d) below mounted on the carriage.
(A) A linear yoke body extending in a horizontal direction, and a pair of yoke arms extending from both ends of the yoke body in a horizontal direction orthogonal to a direction in which the yoke body extends and having a tip bent downward. A magnetizer having a yoke for magnetizing the portion to be inspected; (b) a magnetic powder disperser for dispersing magnetic powder on the portion to be inspected; ) Camera for photographing magnetic powder sprayed on the part to be inspected The magnetic particle flaw detector for a magnetic tube according to claim 1, wherein the camera is installed between a pair of yoke arms. A magnetic particle flaw detector of a quadrupole rotating magnetic field type, in which a pair of magnetizers is installed so that a pair of yoke arms face each other, and approximately at the center of four yoke arms of the pair of magnetizers. 2. The magnetic particle flaw detector for a magnetic tube according to claim 1, wherein the camera is installed. The magnetic tube according to any one of claims 1 to 3, wherein the light is installed at a position where regular reflection light of the irradiation light directed toward the inspected portion on the inner surface of the tube does not enter the camera. Magnetic particle flaw detector. The magnetic particle flaw detector for a magnetic tube according to any one of claims 1 to 4, wherein a body of the bogie is made of a non-magnetic and flexible material. A method for manufacturing a magnetic tube, comprising: a tube forming step of forming a tube; and an inspection step of inspecting the formed tube, wherein the inspection step includes the step of detecting a magnetic particle of the magnetic tube according to claim 1. A method for manufacturing a magnetic tube, comprising inspecting an inner surface of the magnetic tube using an apparatus.

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