Surface inspection device and surface inspection method for the inner surface of a pipe.

Abstract

To provide a surface inspection device and method for inspecting the inner surface of a pipe that can efficiently, inexpensively, and accurately inspect surface defects on the inner surface of a pipe along its entire length. [Solution] The pipe inner surface inspection device according to the present invention comprises an image sensor that has a field of view on the inner surface of the pipe and captures an image of the inner surface of the pipe, and a scanning unit that scans the image sensor along the axial direction of the pipe, wherein the scanning unit is provided with legs having wheels at the contact points with the inner surface of the pipe, which are arranged on one and the other side of the image sensor in the axial direction of the pipe, and at least one of the one and the other side has three or more legs.

Description

Technical Field

[0001] The present invention relates to an inner surface inspection apparatus and a surface inspection method for a pipe inner surface.

Background Art

[0002] In modern society, pipes are used in various scenarios such as infrastructure like buildings and pipelines, transportation equipment, industrial machinery, etc., and their quality is very important from the perspective of safety. In particular, if there are defects on the surface of the pipe, it may lead to a decrease in strength and destruction starting from the defects, resulting in serious damages such as the collapse of structures and the outflow of the contents of pipelines. Among such surface defects, concave-shaped surface defects generated by pushing foreign objects into the pipe during manufacturing processes such as rolling are directly related to wall thickness reduction, and when caused by foreign objects stuck to rolling rolls, etc., they occur continuously in large numbers, so the harmfulness is high. Regarding such surface defects of pipes, it is very important to conduct inspections at the material stage and suppress the outflow as products in order to prevent serious accidents.

[0003] For example, in the case of steel pipes made of steel as a material, products may be shipped through a process of inspecting the presence or absence of surface defects by visually inspecting the appearance after forming. At this time, for surface defects on the outer surface of the steel pipe, visual inspection is easy, and inspections can be carried out under conditions where surface defects are easily detectable. On the other hand, for surface defects on the inner surface of the steel pipe, since one has to look into the inner surface from the outside of the steel pipe, it is very difficult to conduct inspections under conditions where surface defects are easily detectable due to reasons such as the long distance to the surface defect and the visual inspection of the inner part at a very shallow angle. Therefore, although submersible pipe inspections that involve潜入 the inside of the steel pipe for inspection may be carried out in some cases, there are many problems such as it being a dangerous operation and it not being applicable to small-diameter steel pipes for which submersible pipe inspections are difficult in the first place.

[0004] Against this backdrop, there is a strong need for technology to measure the condition of the inner surface of steel pipes and automatically detect concave surface defects, and various technological developments have been carried out in the past. Specifically, Patent Documents 1 and 2 describe a method of inspecting the entire inner surface of a pipe by inserting an ultrasonic probe into the pipe and scanning it. Patent Documents 3 and 4 describe a method of inspecting the entire inner surface of a pipe by inserting an eddy current testing probe into the pipe and scanning it. Furthermore, Patent Document 5 describes a method of detecting defects on the inner surface of a pipe by imaging the inner surface with a camera and obtaining the image. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2014-098631 [Patent Document 2] Japanese Patent Publication No. 2002-340867 [Patent Document 3] Japanese Patent Publication No. 2020-148771 [Patent Document 4] Japanese Patent Publication No. 2013-195141 [Patent Document 5] Japanese Patent Publication No. 2011-069616 [Non-patent literature]

[0006] [Non-Patent Document 1] Ricoh Co., Ltd., RICOH THETA, [online], [searched August 1, 2024], Internet<URL:https: / / ricoh360.com / ja / theta> [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, the methods described in Patent Documents 1 and 2 have many practical problems, such as low inspection efficiency due to the time required for scanning with the ultrasonic probe, the need for water for inspection resulting in large-scale equipment, and the high cost of the ultrasonic probe. Furthermore, the methods described in Patent Documents 3 and 4 have problems not only with inspection efficiency and cost similar to ultrasonic testing, but also with susceptibility to vibration. On the other hand, the method described in Patent Document 5 makes it difficult to accurately detect surface defects on the inner surface of the pipe along its entire length.

[0008] The present invention was made to solve the above problems, and its objective is to provide a surface inspection device and surface inspection method for the inner surface of a pipe that can efficiently, inexpensively, and accurately inspect surface defects on the inner surface of a pipe along its entire length. [Means for solving the problem]

[0009] [1] The pipe inner surface inspection device according to the present invention comprises an image sensor having a field of view on the inner surface of the pipe and capturing an image of the inner surface of the pipe, and a scanning unit that scans the image sensor along the axial direction of the pipe, wherein the scanning unit is provided with legs having wheels at the contact points with the inner surface of the pipe, and at least one of the one and the other sides is provided with three or more of the legs.

[0010] [2] The surface inspection apparatus for the inner surface of a pipe according to the present invention is the surface inspection apparatus for the inner surface of a pipe according to [1], wherein the three or more legs are equipped with a leg length adjustment mechanism that allows the leg length to be adjusted according to the inner diameter of the pipe to be inspected, and are arranged symmetrically on the left and right sides in a plane perpendicular to the axial direction of the pipe, with the vertical direction as the axis of left and right symmetry.

[0011] [3] The surface inspection device for the inner surface of a pipe according to the present invention is the surface inspection device for the inner surface of a pipe according to [1] or [2], wherein the leg portion is equipped with an expandable and contractible mechanism that expands and contracts in accordance with the change in the inner diameter of the pipe in the axial direction of the pipe.

[0012] [4] The surface inspection device for the inner surface of a pipe according to the present invention is, in the surface inspection device for the inner surface of a pipe in [3], the telescopic mechanism includes an elastic element that can be telescoped in the leg length direction.

[0013] [5] The surface inspection method for the inner surface of a pipe according to the present invention includes a step of inspecting surface defects formed on the inner surface of a pipe using the surface inspection device for the inner surface of a pipe according to any one of [1] to [4].

Effect of the Invention

[0014] According to the surface inspection device and the surface inspection method for the inner surface of a pipe according to the present invention, surface defects on the inner surface of a pipe can be inspected efficiently, at low cost, and with high accuracy over the entire length of the pipe.

Brief Description of the Drawings

[0015] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a surface inspection device for the inner surface of a pipe according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing the configuration of the surface inspection device for the inner surface of a pipe as viewed from the direction of arrow A shown in FIG. 1. [Figure 3] FIG. 3 is a diagram for explaining the configuration of the telescopic mechanism.

Mode for Carrying Out the Invention

[0016] Hereinafter, referring to the drawings, the configuration of a surface inspection device for the inner surface of a pipe according to an embodiment of the present invention will be described.

[0017] FIG. 1 is a schematic diagram showing the configuration of a surface inspection device for the inner surface of a pipe according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing the configuration of the surface inspection device for the inner surface of a pipe as viewed from the direction of arrow A shown in FIG. 1. As shown in FIGS. 1 and 2, a surface inspection device 1 for the inner surface of a pipe according to an embodiment of the present invention (hereinafter abbreviated as the surface inspection device 1) is a device for inspecting surface defects existing on the inner surface of a pipe such as a steel pipe along the axial direction of the pipe, and includes a support portion 2, an imaging portion 3, and scanning portions 4a and 4b as main components.

[0018] The support part 2 is composed of a substrate such as a flat steel plate, and is equipped with various devices such as an imaging part 3 necessary for inspecting surface defects. Examples of devices other than the imaging part 3 mounted on the support part 2 include an information processing device and a communication device for processing the data of the image taken by the imaging part 3. Further, when the surface inspection device 1 can travel automatically, a driving device such as a motor and a battery may be mounted. In the present embodiment, the support part 2 is composed of a substrate such as a flat steel plate, but the configuration of the support part 2 is not limited to the present embodiment, and the shape and material of the support part 2 are not particularly limited as long as it has rigidity.

[0019] The imaging part 3 has a field of view on the inner surface of the pipe and is composed of an imaging element that takes an image of the inner surface of the pipe, and outputs the image data of the inner surface of the pipe taken to a terminal device carried by an operator, an information processing device that processes the image data, a storage device such as a memory card, etc. The type of the imaging element is not particularly limited, but a full - circumference imaging element (see Non - Patent Document 1) or a plurality of imaging elements arranged in the circumferential direction of the pipe may be used so that the entire inner surface of the pipe can be inspected without omission. Further, the imaging element may be arranged so that the imaging direction of the image is orthogonal to the axial direction of the pipe. Also, a light source may be arranged near the imaging element, for example, one light source may be arranged in front of and behind the imaging element in the axial direction of the pipe.

[0020] The scanning parts 4a and 4b are arranged before and after the imaging part 3 along the axial direction of the pipe. The scanning part 4a includes a support part 4a1, a leg part 4a2, and a wheel 4a3. Similarly, the scanning part 4b includes a support part 4b1, a leg part 4b2, and a wheel 4b3.

[0021] The support parts 4a1 and 4b1 are composed of a substrate such as a flat steel plate, and are joined to one end and the other end of the support part 2 in the axial direction of the pipe so that the normal direction of the substrate is parallel to the axial direction of the pipe, respectively.

[0022] The legs 4a2 and 4b2 are made up of rod-shaped members, and wheels 4a3 and 4b3 that contact the inner surface of the pipe are connected to the ends of the rod-shaped members. By pulling the string 5 connected to the support part 4b1 to rotate the wheels 4a3 and 4b3 and move the surface inspection device 1 along the axial direction of the pipe (scanning direction shown in Figure 1), the inner surface of the pipe can be inspected efficiently, inexpensively, and accurately along its entire length. In this embodiment, the surface inspection device 1 is moved by pulling the string 5, but the surface inspection device 1 may also be moved by connecting the rod-shaped members to the surface inspection device 1 and operating the rod-shaped members. Furthermore, the surface inspection device 1 may be equipped with a drive device such as a motor so that the surface inspection device 1 can move automatically. In addition, the string 5 may be connected to a position other than the support parts 4a1 and 4b1.

[0023] Furthermore, the legs 4a2 and 4b2 are equipped with a leg length adjustment mechanism (not shown in Figure 1; leg length adjustment mechanism 4b4 shown in Figure 2) that allows the leg length to be adjusted to match the inner diameter of the pipe being inspected. Examples of leg length adjustment mechanisms include a mechanism that adjusts the leg length using a sliding mechanism and a leg length adjustment mechanism with a fixed screw position. By adjusting the length of the legs 4a2 and 4b2 to match the inner diameter of the pipe being inspected so that the wheels 4a3 and 4b3 contact the inner surface of the pipe being inspected, the inner surface of the pipe can be inspected efficiently, inexpensively, and accurately along its entire length.

[0024] Furthermore, multiple legs 4a2 and 4b2 are attached to the support parts 4a1 and 4b1 so as to extend radially toward the inner surface of the pipe, with the center of gravity of the support parts 4a1 and 4b1 as the central position. This prevents the surface inspection device 1 from meandering when it is moved, and allows for stable imaging of the inner surface of the pipe along its entire length, thus enabling accurate inspection of the inner surface of the pipe. It is desirable to adjust the length of the legs 4a2 and 4b2 using the leg length adjustment mechanism so that the center of gravity (center position) of the support parts 4a1 and 4b1 coincides with the axial center position of the pipe being inspected.

[0025] Furthermore, it is desirable to adjust the length of the legs 4a2 and 4b2 using the leg length adjustment mechanism so that the center of gravity of the support parts 4a1 and 4b1 coincides with the axial center of the pipe being inspected. In this embodiment, both the scanning units 4a and 4b are equipped with three legs 4a2 and 4b2, but the number of legs 4a2 and 4b2 is not limited to three, and the scanning units 4a and 4b may be equipped with three or more legs 4a2 and 4b2. Also, the number of legs of one of the scanning units 4a and 4b may be two or less. In addition, the center position of the support parts 4a1 and 4b1 does not necessarily have to coincide with the intersection of the extensions of the three legs 4a2 and 4b2 or the axial center of the pipe.

[0026] Furthermore, if there are three or more legs 4a2 and 4b2, it is preferable to arrange the legs 4a2 and 4b2 symmetrically on a plane perpendicular to the axial direction of the pipe, with the vertical direction as the axis of symmetry. This prevents the surface inspection device 1 from rotating in the circumferential direction of the pipe when it is moved.

[0027] Furthermore, it is preferable that the legs, which are positioned symmetrically on a plane perpendicular to the axial direction of the pipe with the vertical direction as the axis of symmetry, be provided with an extension mechanism that extends and retracts by Δy1 + Δy2 or more in the leg length direction along the inner diameter of the pipe, where Δy1 and Δy2 are the height differences between the height position of the intersection of the extension lines of the three legs 4a2 and 4b2 in the horizontal and vertical ranges of the pipe and the height position of the pipe's axial center, respectively. Examples of extension and retraction mechanisms include spring members. This ensures that even if the roundness (internal shape) of the pipe fluctuates in the longitudinal direction of the pipe, the wheels attached to the legs of the scanning unit always contact the inner surface of the pipe, allowing the surface inspection device 1 to stably inspect the inner surface of the pipe without meandering or rotating in the circumferential direction. It is preferable that the extension and retraction mechanism be provided on the leg that extends in the 12 o'clock direction among the three legs.

[0028] Specifically, in the region of the horizontally elongated elliptical tube P1 shown in Figure 3, the coordinates (x1, y1) of the intersection point between the leg portion 4b2_2 and the inner surface of tube P1 satisfy the following equation (1), where a > b in equation (1). Furthermore, in the circular region of the tube, the centroids of the support portions 4a1 and 4b1 are assumed to coincide with the axial center of the tube.

[0029]

number

[0030] Here, if we let R be the radius of the circular tube, then a can be expressed as a = R + ΔR and b = R - ΔR. Also, if we let (x2, y2) be the coordinates of the intersection point between the leg portion 4b2_2 and the inner surface of the circular tube, then x1 = x2 and y1 ≠ y2. Based on these, by rearranging equation (1) above, y1 can be expressed as shown in equation (2) below.

[0031]

number

[0032] Therefore, the change in the height position Δy of the leg when the surface inspection device 1 moves from the circular region of the pipe to the elongated elliptical region can be expressed as shown in equation (3) below. The parameter θ in equation (3) represents the angle of the extension direction of the leg 4b2_2 with respect to the horizontal direction.

[0033]

number

[0034] Furthermore, if the roundness of the pipe is R, then from equation (3) above, the difference Δy1 between the height position of the intersection point O of the extensions of the three legs 4a2 and 4b2 in the horizontally elongated range of the pipe and the height position of the central axis L of the pipe can be expressed as shown in equation (4) below.

[0035]

number

[0036] Similarly, for the region of the vertically elongated elliptical tube P2 shown in Figure 3, by expressing a=R-ΔR and b=R+ΔR, the difference Δy2 between the height position of the intersection point O of the extensions of the three legs 4a2 and 4b2 and the height position of the tube's central axis L can be expressed as shown in the following equation (5).

[0037]

number

[0038] Therefore, it is desirable that the legs be equipped with an extension mechanism that allows them to extend and retract by Δy1 as shown in equation (4) and Δy2 as shown in equation (5).

[0039] As is clear from the above description, the pipe inner surface inspection device 1, which is one embodiment of the present invention, comprises an imaging unit 3 that has a field of view on the inner surface of the pipe and captures an image of the inner surface of the pipe, and scanning units 4a and 4b that scan the imaging unit 3 along the axial direction of the pipe. The scanning units 4a and 4b are equipped with legs 4a2 and 4b2 that have wheels 4a3 and 4b3 at their contact points with the inner surface of the pipe, and at least one of the two sides has three or more legs 4a2 and 4b2. This makes it possible to efficiently, inexpensively, and accurately inspect surface defects on the inner surface of the pipe along its entire length.

[0040] Although embodiments applying the invention made by the present inventors have been described above, the present invention is not limited by the descriptions and drawings that constitute part of the disclosure of the present invention in this embodiment. For example, in this embodiment, the imaging unit 3 is mounted on the support unit 2, but inspection devices other than the imaging unit 3, such as a laser displacement meter, may also be mounted. Thus, all other embodiments, examples, and operational techniques made by those skilled in the art based on this embodiment are included in the scope of the present invention. [Explanation of Symbols]

[0041] 1. Surface inspection device for the inner surface of a pipe 2 Support part 3. Imaging Unit 4a, 4b Scanning Unit 4a1,4b1 Support part 4a2,4b2 Legs 4a3,4b3 wheels 4b4 Leg length adjustment mechanism 5 strings

Claims

1. An image sensor that has a field of view on the inner surface of the tube and captures an image of the inner surface of the tube, A scanning unit that scans the image sensor along the axial direction of the tube, Equipped with, The scanning unit is equipped with legs having wheels at the contact points with the inner surface of the tube, which are arranged on one and the other side of the image sensor in the axial direction of the tube, and at least one of the one and the other side has three or more of these legs. A surface inspection device for the inner surface of pipes.

2. The surface inspection device for the inner surface of a pipe according to claim 1, wherein the three or more legs are equipped with a leg length adjustment mechanism that allows the leg length to be adjusted according to the inner diameter of the pipe to be inspected, and are arranged symmetrically on the left and right sides in a plane perpendicular to the axial direction of the pipe, with the vertical direction as the axis of left and right symmetry.

3. The surface inspection device for the inner surface of a pipe according to claim 1, wherein the leg portion is equipped with an expandable / contractable mechanism that expands and contracts in accordance with a change in the inner surface shape of the pipe in the axial direction of the pipe.

4. The pipe inner surface inspection apparatus according to claim 3, wherein the extension mechanism comprises an elastic element that can extend and contract in the direction of the leg length.

5. A method for inspecting the inner surface of a pipe, comprising the step of inspecting surface defects formed on the inner surface of a pipe using a pipe inner surface inspection device described in any one of claims 1 to 4.

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