JP6846867B2 - Pipe inner surface inspection device and pipe inner surface inspection method - Google Patents

Description

The present invention relates to a pipe inner surface inspection device for inspecting an inner wall surface of a steel pipe or the like and a pipe inner surface inspection method.

The electric resistance sewn steel pipe is required to have the same strict appearance quality as the outer surface side on the inner surface side of the steel pipe, as well as high roundness and dimensional accuracy on the inner diameter side.
A steel pipe is made into a tubular shape by gradually bending a steel strip in the width direction with a large number of forming rolls, and the seams between the end faces are continuously electrically resistance welded (electrically welded) along the longitudinal direction. Manufactured. Welding beads are continuously generated on the seam portion of the pipe by electric stitch welding along the longitudinal direction of the pipe. At the same time, spatter debris flying during welding is scattered on the inner wall surface of the pipe.
In order to smooth the inner surface of the steel pipe, a method of cutting the weld bead by inserting an internal cutting device into the steel pipe after welding is performed. This type of internal cutting apparatus includes a cutting tool for cutting a weld bead and wheels for movably supporting the main body of the device and applying a reaction force to the cutting tool (see, for example, Patent Document 1).

However, even after cutting the weld bead in the steel pipe using the internal cutting device, for example, as shown in FIG. 12, the internal cutting defect of the weld bead, the internal surface defect due to the mechanical contact of the internal cutting device, and the internal cutting device Crater-like trampling scratches and the like may occur when the wheels of the wheel trample on the spatter debris.

In the intermediate inspection of steel pipe products, it is necessary to detect such defects such as internal machining defects and spatter trampling defects on the inner surface of the pipe in advance. Therefore, conventionally, a pipe inner surface inspection device that is inserted into the pipe and inspects defects while photographing the inner wall surface thereof has been proposed (see, for example, Patent Documents 2 and 3).

JP-A-2009-241152 Japanese Patent Publication No. 2004-509321 Japanese Unexamined Patent Publication No. 2011-11255

However, in the inspection device described in Patent Document 2, the presence of a flaw on the inner surface of the tube can be detected by an imaging apparatus using a wide-angle lens, but the depth of the flaw cannot be detected. Further, the inspection device described in Patent Document 3 can accurately inspect the state of flaws whose positions are known in advance, such as cutting defects generated in the seam portion in the longitudinal direction of the pipe, but randomly on the inner surface of the pipe. It was not suitable for detecting spatter trampling flaws that occur.

The present invention has been made to solve such a conventional problem, and provides a pipe inner surface inspection device or a pipe inner surface inspection method capable of accurately detecting defects such as spatter marks randomly generated on the inner surface of a pipe. It is intended to be provided.

The pipe inner surface inspection device of the present invention made to solve the above problems is a self-propelled pipe inner surface inspection device that can move in a cylindrical pipe, and is a self-propelled pipe inner surface inspection device between a traveling driving means and a traveling guiding means. a support member bridged eccentric position from the longitudinal central axis of the tube, the beam profiler disposed on the support member, about the central axis which coincides with the central axis of the beam profiler together with the support member The drive guide, which is provided with a swivel means for swiveling and is arranged on the traveling drive means side and is pressed into contact with the inside of the pipe, is provided with four support legs arranged in an H shape and is on the central axis. The drive wheels installed on the support legs come into contact with the inner surface of the tube with the same pressing force due to the equal urging force from the coil springs provided in the above to the support legs via the bearing links. It is a structure that supports the surface inspection device, and is characterized in that the drive guide that is arranged on the traveling guide means side and is pressed into contact with the inside of the pipe has a structure that supports the inside surface inspection device of the pipe with three wheels. is there.

Further, the pipe inner surface inspection device includes a pipe inner circumference scanning device in which the beam profiler is arranged in the central axis direction, and the pipe inner circumference scanning device is a plane orthogonal to the longitudinal center line of the pipe to be inspected. It is preferable to scan toward the inner surface of the tube inside.

Further, in the tube inner surface inspection device, the in-pipe all-around scanning device includes a slit laser light emitting unit and an imaging unit, and the slit laser light emitting unit is in a plane orthogonal to the longitudinal center line of the tube to be inspected. It is preferable to scan the slit laser beam toward the inner surface.

Further, in the tube inner surface inspection device, it is preferable that the distance between the slit laser light emitting unit and the imaging unit can be adjusted.

Further, the pipe inner surface inspection method of the present invention is a pipe inner surface inspection method for inspecting the inner surface of a pipe by a self-propelled pipe inner surface inspection device equipped with a beam profiler, and is between a traveling driving means and a traveling guiding means. While the beam profiler supported on the support member bridged at the eccentric position is held in the first swivel position and the pipe inner surface inspection device is run in the outward path direction of the pipe, the pipe is operated by the beam profiler. The beam profiler is centered in the longitudinal direction of the tube together with the support member in order to swivel the beam profiler from the first swivel position to the second swivel position at the end position of the tube and the step of photographing the inner surface profile of the tube. While the step of turning around the axis line and the pipe inner surface inspection device running in the return path direction of the pipe with the beam profiler held at the second turning position, the inner surface profile of the pipe is obtained by the beam profiler. and a step of photographing, are arranged in front Symbol traveling drive means side, driving guide in contact by being pressed by the tube is provided with four support legs arranged in H-type, the center axis Due to the equal urging force from the provided coil spring to the support leg via the support link, the drive wheels installed on the support leg come into contact with the inner surface of the pipe with the same pressing force. supporting an inspection apparatus, placed in front Symbol travel guidance means side, driving guide in contact by being pressed by the tube is characterized in a Turkey support the inner surface inspection apparatus in three wheels.

Further, in the pipe inner surface inspection method, the drive guide arranged on the traveling drive means side and pressed into contact with the inside of the pipe uses a structure in which the pipe inner surface inspection device is supported by four wheels, and the traveling guide means side. It is preferable to use a structure that supports the pipe inner surface inspection device with three wheels for the drive guide that is arranged in the pipe and is in contact with the inside of the pipe.

Further, in the pipe inner surface inspection method, the beam profiler uses an in-tube all-around scanning device arranged in the central axis direction, and the in-tube all-around scanning device is used to perform a plane orthogonal to the longitudinal center line of the tube to be inspected. It is preferable to scan the inner surface of the tube inside.

Further, in the pipe inner surface inspection method, a slit laser light emitting unit and an imaging unit are arranged in the pipe all-around scanning device, and the slit laser light emitting unit causes the tube to be in a plane orthogonal to the longitudinal center line of the tube to be inspected. It is preferable to scan toward the inner surface of the surface using a slit laser beam.

Further, in the tube inner surface inspection method, it is preferable that the distance between the slit laser light emitting unit and the imaging unit can be adjusted.

According to the pipe inner surface inspection apparatus or the pipe inner surface inspection method of the present invention, it is possible to accurately detect defects such as spatter defects that occur randomly on the inner surface of the pipe. In addition, the movement of the pipe inner surface inspection device in the pipe can be stabilized.

It is a block diagram which illustrates the side surface of the pipe inner surface inspection apparatus by one Embodiment of this invention. It is a side view which illustrates the traveling drive means. It is the figure which looked at the pipe inner surface inspection apparatus from the rear in order to further illustrate the traveling drive means. It is a side view which illustrates the traveling guidance means. It is the figure which looked at the pipe inner surface inspection apparatus from the front in order to further illustrate the traveling guidance means. It is a graph which shows the result of having tested the running performance by the pipe inner surface inspection apparatus. It is a side view which illustrates the beam profiler. It is a figure which illustrates the inner surface profile photographed on the inner surface of a tube. It is a figure which illustrates the image synthesized based on the inner surface profile. It is a flow chart for demonstrating the pipe inner surface inspection method by the pipe inner surface inspection apparatus. It is a flow figure for demonstrating the pipe inner surface inspection method by the pipe inner surface inspection apparatus of another embodiment. It is a figure for demonstrating the occurrence example of the defect of a pipe.

The present invention relates to a pipe inner surface inspection device, and is a self-propelled device provided with a drive device (traveling drive means) by itself.
The self-propelled pipe inner surface inspection device is provided with traveling drive means on one of the front and rear sides of the inspection device, and is provided with traveling guidance means on the other side. The structure is such that a beam profiler is connected between the traveling driving means and the traveling guiding means.
Hereinafter, a self-propelled pipe inner surface inspection device, which is provided with traveling drive means on one of the front and rear sides of the pipe inner surface inspection device and the other is a traveling guidance means, will be described as an example.

FIG. 1 is a side view of a self-propelled pipe inner surface inspection device 10 according to an embodiment of the present invention. The pipe inner surface inspection device 10 according to the present embodiment enters a cylindrical pipe such as an electrosewn steel pipe or is inserted into the pipe, and while traveling along the longitudinal direction in the pipe, a defect such as a defect on the inner surface of the pipe is obtained. Inspect the condition of. As illustrated in FIG. 1, the pipe inner surface inspection device 10 is provided with a traveling drive means 20 on one end side (temporarily referred to as a rear end portion) and a traveling guidance means 30 on the other end side (temporarily referred to as a front end portion). To be equipped. A beam profiler 40 is connected between the traveling driving means 20 and the traveling guiding means 30. The pipe inner surface inspection device 10 is configured to be able to reciprocate (or travel) along the direction in which the traveling guide means 30, the beam profiler 40, and the traveling driving means 20 are connected.

(Traveling drive means)
The traveling driving means 20 is provided at, for example, the rear end of the pipe inner surface inspection device 10. Here, FIG. 2 is an enlarged side view showing a traveling unit main body portion of the traveling driving means 20. Further, FIG. 3 is a view of the pipe inner surface inspection device 10 as viewed from the rear of the central axis.

The traveling drive means 20 includes a drive motor 21 provided in the main body of the traveling unit, and preferably a drive guide including four drive wheels 22 (22a, 22b) and support legs 23 for supporting the drive wheels 22. There is. A worm gear 24 meshes with the shaft of the drive motor 21, and the torque of the drive motor 21 is transmitted to the drive wheels 22 via an endless belt or the like (not shown) in the support leg portion 23.

The support legs 23, 23 having the upper and lower drive wheels 22, 22 at their respective tips are rotatably supported around the shaft of the worm gear 24 on each base end side. Further, bearing links 26, 26 are axially supported at intermediate positions of the support legs 23, 23. The other ends of the bearing links 26, 26 are connected to a slider 27 that slides along a rod 28 extending rearward from the axial center of the pipe inner surface inspection device 10. The slider 27 is always urged forward by a coil spring 29 supported by the rod 28. As a result, the drive wheels 22 are pressed against and in contact with the inner surface of the pipe to be inspected.

According to the link mechanism of the traveling drive means 20, the urging force from the coil spring 29 acts evenly on the upper and lower support legs 23 and 23 in a direction in which they spread from each other, whereby the upper and lower drive wheels 22 22 comes into contact with the inner surface of the pipe with the same pressing force. That is, even if the inner diameters of the pipes are different, the drive wheels 22 and 22 can be brought into contact with the inner surface of the pipe with equal pressing force within the range in which the upper and lower support legs 23 and 23 can move. As a result, the torque from the drive motor 21 can be applied to the inner surface of the pipe via the drive wheels 22 and 22, and a propulsive force can be generated in the inner surface inspection device 10 of the pipe.

Further, by changing the rotation direction of the shaft of the drive motor 21, the pipe inner surface inspection device 10 can be reciprocated in the pipe. Further, by applying the urging force from the coil spring 29 evenly to the upper and lower drive wheels 22 and 22, the traveling drive means 20 is always held at the center of the pipe even if the inner diameters of the pipes are different, and the pipe inner surface inspection device is used. 10 can be run stably.

Further, by counting the pulse output to the drive motor 21, the position of the pipe inner surface inspection device 10 in the pipe, that is, the inspection position by the beam profiler 40 described later can be grasped. Further, a rotary encoder may be provided on the shaft of the drive motor 21 or the worm gear 24, and the inspection position may be detected based on the count output thereof. Information such as the inspection position may be output to an external inspection control device at any time during the inspection operation by the pipe inner surface inspection device 10, or is temporarily stored in the memory of the control device mounted on the pipe inner surface inspection device 10. May be recorded.

It is also conceivable that the pipe inner surface inspection device 10 gradually turns (torsion rotation about the traveling shaft) during traveling due to mechanical imbalance or the like. However, such an undesired turning operation can be prevented by taking measures such as providing a weight portion such as a weight under the drive motor 21 or the turning motor 45 described later to lower the position of the center of gravity.

The position of the pipe inner surface inspection device 10 in the pipe, that is, the inspection position by the beam profiler 40 described later can be detected based on, for example, the amount of movement of the traveling driving means 20. Information such as the inspection position may be output to an external inspection control device at any time during the inspection operation by the pipe inner surface inspection device 10, or is temporarily stored in the memory of the control device mounted on the pipe inner surface inspection device 10. May be recorded.

(Traveling guidance means)
FIG. 4 is an enlarged side view showing the traveling guidance means 30. Further, FIG. 5 is a view of the pipe inner surface inspection device 10 as viewed from the front of the central axis. The traveling guidance means 30 is provided at, for example, the front end of the pipe inner surface inspection device 10.

In the traveling guide means 30, a plurality of guide wheels 31, 31, 31 that come into contact with the inner surface of the pipe and roll freely are supported by the tip portions of the support legs 32, 32, 32 that extend radially. The drive guide that is pressed into contact with the inside of the pipe preferably has a structure in which the pipe inner surface inspection device 10 is supported by three wheels. In that case, the base ends of the respective support legs 32 are pivotally supported by the shaft 34 at the tip of the rod 33 extending forward from the axis center of the pipe inner surface inspection device 10, with mutual angles distributed at 120 degrees. .. That is, as shown in FIG. 5, when the pipe inner surface inspection device 10 is viewed from the front, the three support legs 32, 32, 32 are pivotally supported so as to rotate evenly in a radial manner.

Further, a bearing link 35 is pivotally supported at an intermediate position of each support leg portion 32. The other end of each bearing link 35 is connected to a slider 36 that slides along the rod 33. The slider 36 is connected to the main body of the linear motion cylinder 37 and is provided so as to interlock with the linear motion cylinder 37.

That is, by extending the linear motion cylinder 37, the three support legs 32, 32, 32 can be rotated in a direction in which they spread from each other. Then, the guide wheels 31, 31, and 31 are brought into contact with the inner surface of the pipe with equal pressing force according to the inner diameter of the pipe. As a result, even if the inner diameters of the pipes are different, the pipe inner surface inspection device 10 that moves in the pipe can always be held at the center of the pipe to guide the movement of the device.

FIG. 6 shows the results of measuring the amount of running deviation when the inner diameter of the pipe is φ114.3 mm (Example 1), φ169.0 mm (Example 2), and φ190.7 mm (Example 3). Further, as a comparative example, the figure also shows the results when the front and rear drive guides have two wheels (Comparative Example 1) and when the front and rear drive guides have three wheels (Comparative Example 2).

As described above, in the present embodiment, the drive guides arranged on the traveling drive means side and pressed into the pipe and in contact with each other have a structure in which the pipe inner surface inspection device 10 is supported by four wheels, and are arranged on the traveling guide means side. The drive guide, which is pressed into the pipe and is in contact with the pipe, has a structure in which the pipe inner surface inspection device 10 is supported by three wheels, thereby enabling stable running in the pipe.

(Beam profiler)
The beam profiler 40 is provided with an in-pipe all-around scanning device. The in-pipe all-around scanning device may be any device capable of observing the entire in-tube, and examples thereof include a slit laser, natural light, infrared rays, and ultrasonic waves. Here, the slit laser, which is the least susceptible to disturbance, is taken as an example and described below. explain. The present invention is not limited to scanning with a slit laser. In the example of FIG. 1, the slit laser all-around scanning device includes a slit laser light emitting unit 41 and an imaging unit 42, which are arranged on the central axis of the tube inner surface inspection device 10.

FIG. 7 is a side view showing the configuration of the beam profiler 40. The beam profiler 40 is supported on one side of a support plate member 43 bridged between the traveling driving means 20 and the traveling guiding means 30. The beam profiler 40 includes a slit laser light emitting unit 41 and an imaging unit 42, which are arranged on the central axis of the tube inner surface inspection device 10.

Here, the "center axis" in which the slit laser light emitting unit 41 and the imaging unit 42 are arranged coincides with the longitudinal center line of the tube. Further, the direction of the central axis coincides with the direction in which the pipe inner surface inspection device 10 moves (or travels).

The slit laser light emitting unit 41 according to the example of FIG. 7 is provided so as to be orthogonal to the central axis in the longitudinal direction of the tube and scan the slit laser light around the central axis. That is, during the inspection operation, the slit laser light is emitted in a virtual plane orthogonal to the longitudinal center line of the target tube, and the slit laser light is linearly emitted on the inner surface of the tube along the inner circumference of the tube. Be projected.

As a result, in the defective portion of the inner surface of the pipe, an inner surface profile as shown in FIG. 8, for example, is observed. By taking an image of such an inner surface profile by the imaging unit 42, not only the shape and size of, for example, spatter trampling flaws, which are randomly generated on the inner surface of the tube, but also the depth of the flaws to a certain extent can be accurately measured. Can be done.

The information of the slit laser projection image (inner surface profile) taken by the imaging unit 42 is output to, for example, an external inspection control device together with the inspection position information of the tube inner surface inspection device 10. The inspection control device can quantitatively measure the shape, size, depth, etc. of defects such as spatter marks from the variation of the slit laser projection image (inner surface profile) by using the slit laser projection method. In addition, the inspection control device can associate the inspection position information on the inner surface of the pipe where the defect is found with the defect measurement information. The inspection control device can also perform detailed and intuitive analysis of defects such as defects by performing processing such as synthesizing profiles as shown in FIG. 9 based on the photographed inner surface profile. As a result, the position and amount of defects that need to be repaired can be quantitatively grasped, and efficient repair is possible. In addition, it is possible to avoid making unnecessary modifications and expect an effect of improving ability.
The control device mounted on the tube inner surface inspection device 10 may be configured to measure defects based on the slit laser projected image by the imaging unit 42.

Further, it is preferable that the relative distance (interval) between the slit laser light emitting unit 41 and the imaging unit 42 in the central axis direction can be adjusted. For example, as shown in FIG. 7, by appropriately adjusting the front and rear positions of the imaging unit 42, the angle of the slit laser light incident on the imaging unit 42 can be made constant regardless of the inner diameter of the tube to be inspected. it can. This makes it possible to inspect pipes with various inner diameters.

Further, the pipe inner surface inspection device 10 according to the present embodiment includes a swivel motor 45 capable of swiveling the beam profiler 40 around a moving (or traveling) central axis.

Next, a pipe inner surface inspection method by the pipe inner surface inspection device 10 will be described with reference to the flow of FIG. It is assumed that the pipe inner surface inspection device 10 is connected to, for example, an external inspection control device by wire or wirelessly, and its operation is controlled by the inspection control device. However, it may be autonomously controlled by a control device mounted on the main body of the pipe inner surface inspection device 10.

First, the pipe inner surface inspection device 10 enters or is inserted into the pipe to be inspected. The beam profiler 40 is held in the first turning position. In this state, the inner surface profile of the pipe is photographed by the beam profiler 40 while the pipe inner surface inspection device 10 is running in the outward direction of the pipe (FIG. 10 (a)).

Next, at the end position of the pipe, the control device drives the swivel motor 45 to invert the beam profiler 40 from the first swivel position to the second swivel position, for example 180 degrees (FIG. 10 (b)). Then, with the beam profiler 40 held in the second turning position, the inner surface profile of the pipe is photographed by the beam profiler 40 while the pipe inner surface inspection device 10 is reversed and traveled in the return direction of the pipe (FIG. 10 (c)). ).

In the present embodiment, when the pipe inner surface inspection device 10 moves in the outward direction of the pipe, the support plate member 43 supporting the beam profiler 40 becomes a blind spot, and it is conceivable that the lower profile of the pipe inner surface is not photographed. However, when the pipe inner surface inspection device 10 moves in the return direction, the turning position of the beam profiler 40 is reversed, so that the profile information below the pipe inner surface, which was a blind spot, can be complemented. Therefore, all defects randomly generated on the inner surface of the pipe, including, for example, spatter marks, can be detected with high accuracy.

The beam profiler 40 may be supported by two or more support plate members 44, 44 that are bridged between the traveling driving means 20 and the traveling guiding means 30. According to the pipe inner surface inspection device 11 of this embodiment, the rigidity of the entire pipe inner surface inspection device can be increased, and the running stability can be improved.

For example, in the pipe inner surface inspection device 11 of the embodiment in which the beam profiler 40 is sandwiched between the two support plate members 44, 44, the state of the inner surface of the pipe is inspected as follows. First, the beam profiler 40 is held in the first turning position, and in that state, the inner surface profile of the pipe is photographed by the beam profiler 40 while the pipe inner surface inspection device 11 is running in the outward path direction of the pipe (FIG. 11 (a)). ).

Next, at the end position of the pipe, the control device drives the swivel motor 45 to swivel the beam profiler 40, for example, 90 degrees from the first swivel position (FIG. 11B). Then, the inner surface profile of the pipe is photographed by the beam profiler 40 while the pipe inner surface inspection device 11 is reversed and traveled in the return path direction of the pipe (FIG. 11 (c)).

In the present embodiment, when the pipe inner surface inspection device 11 moves in the outward path direction of the pipe, the upper and lower support plate members 44, 44 supporting the beam profiler 40 become blind spots, and the upper and lower profiles of the pipe inner surface are not photographed. However, when the pipe inner surface inspection device 11 moves in the return direction, the beam profiler 40 is turned 90 degrees from the first turning position, so that the upper and lower profiles of the pipe inner surface, which was a blind spot, can be photographed and complemented. it can. As a result, all defects including spatter marks and the like can be accurately detected over the entire circumference of the inner surface of the pipe.

10, 11 Pipe inner surface inspection device 20 Travel driving means 30 Travel guidance means 40 Beam profiler (in-pipe all-around scanning device)
45 swivel motor

Claims (8)

A self-propelled pipe inner surface inspection device that can move inside a cylindrical pipe.
A support member bridged between the travel drive means and the travel guide means at a position eccentric from the central axis in the longitudinal direction of the pipe, and a beam profiler arranged on the support member.
And a pivoting means for pivoting said beam profiler about the central axis which coincides with the central axis together with the support member,
The drive guide, which is arranged on the traveling drive means side and is pressed into contact with the inside of the pipe, has four support legs arranged in an H shape, and is a support link from a coil spring provided on the central axis. The structure is such that the drive wheels installed on the support legs support the pipe inner surface inspection device with four wheels that come into contact with the inner surface of the pipe with the same pressing force by an even urging force to the support legs via the above. A pipe inner surface inspection device, which is arranged on the traveling guide means side and has a structure in which a drive guide that is pressed and contacts the inside of the pipe supports the pipe inner surface inspection device with three wheels. The beam profiler includes an in-pipe all-around scanning device arranged in the central axis direction.
The pipe inner surface inspection device according to claim 1, wherein the pipe inner circumference scanning device scans toward the inner surface of the pipe in a plane orthogonal to the longitudinal center line of the pipe to be inspected. The in-tube all-around scanning device includes a slit laser emitting unit and an imaging unit, and the slit laser emitting unit emits slit laser light toward the inner surface of the tube in a plane orthogonal to the longitudinal center line of the tube to be inspected. The pipe internal surface inspection apparatus according to claim 2, wherein the scanning device is performed. The tube inner surface inspection device according to claim 3, wherein the distance between the slit laser light emitting unit and the imaging unit can be adjusted. It is a pipe inner surface inspection method that inspects the inner surface of a pipe with a self-propelled pipe inner surface inspection device equipped with a beam profiler.
With the beam profiler supported on the support member bridged at the eccentric position between the traveling driving means and the traveling guiding means held at the first turning position, the pipe inner surface inspection device is moved in the outward path direction of the pipe. The process of photographing the inner surface profile of the tube with the beam profiler while traveling to
A step of swirling the beam profiler together with the support member about the central axis in the longitudinal direction of the pipe in order to swivel the beam profiler from the first swivel position to the second swivel position at the end position of the pipe.
Wherein the inner surface inspection device while traveling in the backward direction of the tube in a state where a beam profiler was held in the second pivot position, viewed including the step of photographing the inner surface profile of the pipe by the beam profiler,
The drive guide, which is arranged on the traveling drive means side and is pressed into contact with the inside of the pipe, has four support legs arranged in an H shape, and is a support link from a coil spring provided on the central axis. the uniform biasing force to the support leg via a support the inner surface inspection apparatus in four-wheel that the installed drive wheels are in contact with the same pressing force to the inner surface of the tube to the supporting leg, before Symbol travel arranged on the guide means side, the pressed driving guide in contact with the inner surface inspection wherein the benzalkonium support the inner surface inspection device in three-wheel into the tube. The beam profiler uses an in-tube all-around scanning device arranged in the central axis direction.
The pipe inner surface inspection method according to claim 5, wherein the pipe inner circumference scanning device scans the inner surface of the pipe in a plane orthogonal to the longitudinal center line of the pipe to be inspected. A slit laser light emitting unit and an imaging unit are arranged in the in-tube all-around scanning device, and the slit laser light emitting unit directs the slit laser light toward the inner surface of the tube in a plane orthogonal to the longitudinal center line of the tube to be inspected. The method for inspecting the inner surface of a pipe according to claim 6, wherein scanning is performed using a laser. The method for inspecting the inner surface of a tube according to claim 7, wherein the distance between the slit laser light emitting unit and the imaging unit can be adjusted.

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