JPH0339639A - Inspecting device for inner surface of pipe - Google Patents

Abstract

PURPOSE:To accurately inspect a defect generated on the in-pipe surface with high efficiency by arranging a camera and a light source opposite to each other at an interval and coupling them together by a spirally curved coupler. CONSTITUTION:The device 1 consists of the camera 2, the light source 3 which is arranged in front of it, and the coupler 4 which couples them together. The camera 2 is put in a holder 5. A wire 7 for scanning is connected to the rear part of the camera 2, a roller 8 for movement is fitted outside the holder 5, and metal fittings 9 connecting a rope for device movement are fixed to its rear part. The light source (miniature electric bulb) 3 is fitted to a light source support device 11 through a socket 10, a roller 12 is provided to its outer peripheral part, and metal fittings 13 which clamping the rope for device movement are fixed to the center part. The holder 5 and support device 11 are coupled together by the rigid coupler 4. The coupler 4 is curved spirally, its curved part is positioned where the highest brightness is obtained, and the angle of curvature is about 40 - 60 deg..

Description

Detailed Description of the Invention (Field of Industrial Application) This invention relates to an inspection device for the inner surface of a pipe, and more specifically, to an inspection device for inspecting the inner surface of a pipe, in which a camera and a light source are placed facing each other with a distance between them, and are connected by a spirally curved connector. This invention relates to a surface inspection device.

(Prior Art) Seamless steel pipes and welded steel pipes are manufactured by an inclined rolling method and a welding method, respectively. At that time, the surface of those tubes has baldness,
Various defects such as pockmarks and pits occur. The above-mentioned pits are mainly formed when iron scraps are pushed into the surface of the pipe by rolls during pipe manufacturing, and after they peel off, the pits are small with a diameter of approximately 0.2ms+ and a depth of about 0.2 to 3 holes. It is a hole.

However, the pits may occur not only during the manufacture of steel pipes but also during storage of the product steel pipes. For example, it can also occur if cutting water used for thread cutting of steel pipes or water used for water pressure tests remains inside the pipes.

If such pits exist on the inner surface of the steel pipe, corrosion may occur therefrom or may progress, resulting in a bursting accident.

Therefore, it is necessary to precisely inspect the pits and ensure that they are removed. Conventionally, fiberscopes and endoscopes have been used for this inspection. Fiberscopes have the advantage of being able to inspect even long pipes, but they are very expensive and have the disadvantage of long inspection distances (which can result in large color attenuation). Endoscopes are relatively inexpensive, have excellent color tone and resolution, and do not require much maintenance, but they can only be used for a distance of 6 m at most, and cannot be used with longer steel pipes. The problem is that it cannot be used.

(Intelligence to be Solved by the Invention) An object of the present invention is to appropriately arrange the camera and light source and how to connect them, and accurately detect defects occurring on the inner surface of the pipe.
Moreover, it is an object of the present invention to provide an inspection device for inspecting the inner surface of a pipe that can be inspected with high efficiency.

(Means for Solving the Problems) Tube inner surface inspection devices such as fiberscopes and endoscopes have the above-mentioned problems. Therefore, the inventors of the present invention have repeatedly studied a device that can inspect pipes with high precision and efficiency, regardless of their size or length. First, as shown in Figure 2(a), a camera 2 with a focal length of 7.5 m and an angle of view of 87 degrees
We made a device with a light source 3 attached to it, and inspected a pit P with a diameter of 0.4++n and a depth of 0.3m+s dug on the inner surface of the tube T, and its condition! It was displayed on a TV monitor (not shown). As a result, a part of the light beam emitted from the light source 3 is reflected by the pit P and enters the camera 2 as shown in the figure, but the light source 3
and camera 2 are on the same side with respect to pit P, so IT
The image of pit P projected on V appears white. Moreover, since the inner surface of the steel pipe T was shot blasted, the background was also white, and the S/N ratio was extremely low (S stands for signal, N stands for noise, and the S/N
The larger the value, the better the sensitivity), that is, the sensitivity is extremely poor.

Therefore, a light source 3 was placed in front of the camera 2 as shown in FIG. 2(b). In this case, since the camera 2 and the light source 3 are on opposite sides to the pit P, a part of the light beam emitted from the light source 3 enters the bit P and then bends and enters the camera 2. At this time, a shadow E is generated within the pit P as shown in the figure. It has become clear that the S/N ratio becomes extremely large due to this shadow E, and that even minute bits can be detected.

However, since this device uses three straight wires W (piano wire with a diameter of 1.5 ms) to connect the camera 2 and the light source 3, the r'rv-
r- = 3 straight lines on the tar! III (A, B, C)
It was photographed out of nowhere. These lines do not change their position even if the device is moved, so the bit at the A-C4il position is hidden by these lines and is not detected.
When the wire W connecting the light source 3 and the light source 3 was bent into a spiral shape, spiral lines (a, b, c) appeared on the ITV monitor as shown in FIG. 3(b). Since the a'wc line has a spiral shape, when the device moves, there are no hidden parts, and it has become clear that the inner surface of the tube can be thoroughly inspected. Initially, in the case of this device, since the camera 2 and the light source 3 were placed facing each other, there was concern that some of the light rays would enter the camera directly and cause a Halley scene, but due to the distance between the camera and the light source and the light source. It was found that if the strength was set appropriately, such a phenomenon would not occur at all.

This invention has been made based on the above findings, and its gist is ``The invention has a camera holder and a light source support that run inside a tube, the camera and the light source are arranged facing each other at a predetermined interval, A pipe inner surface inspection device in which the camera holder and light source support are connected by a spirally curved connector.
It is in.

(Function) Hereinafter, one example of the inspection device of the present invention will be explained using the drawings. FIG. 1 is a side view (partially a cross-sectional view) of the device. It is configured. The camera 2 is housed in a holder 5, and a filter 6 is provided on the front of the holder 5 to prevent heat from affecting the camera. Further, a scanning wire 7 is connected to the rear of the camera. The holder 5 that houses the camera is replaced each time the size of the steel pipe to be inspected changes. A plurality of rollers 8 are attached to the outside of the holder 5 so that it can move smoothly within the tube, and a metal fitting 9 for connecting a rope for moving the device is fixed to the rear thereof. Note that if the cage 5 is provided with a length measuring roller (not shown), it will be more effective to confirm the internal defect position.

The light source 3 is, for example, a 100V, 40W miniature light bulb, and is attached to a light source supporter 11 via a socket 10. The light source support 11 used is one that matches the size of the steel pipe. A roller 12 is provided on the outer periphery of the supporter 11 so that it can be moved within the steel pipe without any trouble, similar to a camera holder, and a roller 12 is provided at the center of the light source supporter 11 on the opposite side from the light source 3 for use in moving the device. A metal fitting 13 for fastening the lobes is fixed. In this pipe inner surface inspection apparatus 1, a light source 3 is disposed in front of a camera 2, so a holder 5 that houses the camera and a support 11 that mounts the light source are connected by a connecting body 4. This link 4 is helically curved for the reasons mentioned above. The connecting body 4 should be as thin as possible, and should also be rigid so that the distance between the camera holder and the light source support does not change. For example, piano wire is suitable.

Incidentally, the distance between the camera and the light source and the intensity of the light source are determined so that the focal range of the camera is the brightest. For example, when inspecting a steel pipe with an inner diameter of 76m5 using a device equipped with a camera with a focal length of 7.5cm and an angle of view of 87 degrees and a 40W light source, the area in front of the camera from 20 to 70-1 will be the brightest. The distance between the camera and the light source is 170■
Met. If the light source is too strong, it will cause a flash of light, and if the light source is too close to the camera, the heat from the light source will adversely affect the camera.

The connecting body does not need to be curved over its entire length, and may be partially curved, but it is best to position it at a position corresponding to the part where the light is the brightest, which in the above example corresponds to 20 to 70-1 points in front of the camera. Also, the bending angle of the connecting body is preferably 40 to 60 degrees; if the bending angle is too small, the connecting body will cause bulges when viewed on an ITVT monitor. If the angle is too large, many spiral lines will be projected on the ITVT monitor, making it difficult to see defects.

Next, a case in which the inner surface of a tube is inspected using the above-mentioned apparatus will be explained. This inspection device 1 is normally used with a VTR or ITV. FIG. 4 shows a case where they are used, and the inspection device 1 is connected to a VTR by a scanning wire 7, and
Connected to TVT monitor. After being configured in this way, the inspection device 1 is inserted into the steel pipe T from one end and moved to the other end.

The movement is performed by pulling the row 114 tied to the metal fitting 13 of the light source supporter 11. During the movement, the inner surface of the tube is photographed by a camera, and the inner conditions of the tube are recorded on the VTR and displayed on the ITVT monitor for inspection. It will be done. Furthermore, by using the apparatus having the above configuration, it becomes possible to automatically determine internal defects by inputting the size, position, density, etc. of the shadow appearing on the ITV to the CPU and calculating it. In the above description, the case of inspecting the pits of steel pipes was taken as an example, but it goes without saying that the present invention is not limited to this and can be used to inspect the inner surface of pipes made of any material.

(Example) Hereinafter, the pipe inspection device of the present invention will be explained with reference to Examples.

Connect the VTR and ITV to the device shown in Figure 1, and
The configuration was as shown in the figure. and outer diameter 88.9-1,
100 steel pipes with an inner diameter of 76.0 mm and a length of 8,534 to 9.753 mm were inspected. As a result, even very fine pits with a diameter of about 0.4-1 and a depth of about 0.30 were detected.

For comparison, when the same pit was inspected with a fiberscope, such minute defects could not be detected.

(Effects of the Invention) As explained above, by using the apparatus of the present invention, even minute defects on the inner surface of a pipe can be inspected with high precision and efficiency.

[Brief explanation of drawings]

FIG. 1 is a partially sectional side view of the pipe internal surface inspection device of the present invention, FIG. 2(a) is a schematic side view of a prototype device that integrates a camera and a light source, and FIG. 2(b) is a camera Figure 3 (a) is a diagram of an ITVT monitor image when a straight wire is used to connect the camera and light source, and Figure 3 (b) is a schematic side view of a prototype device in which the camera and light source are arranged facing each other. FIG. 4 is a diagram showing an ITVT monitor image when a curved wire is used to connect the tube and the light source, and FIG. 4 is a diagram showing the inspection state of the inner surface of the tube by the apparatus of the present invention. ■ is an inspection device, 2 is a camera, 3 is a light source, 4 is a coupling body, 5
is a camera holder, 6 is a filter, 7 is a scanning wire, 8
, 12 is a roller, 9.13 is a metal fitting, 10 is a sowing catch, 11 is a light source supporter, and 14 is a lobe.

Claims (1)

[Claims] It has a camera holder and a light source support that run inside the tube,
The camera and the light source are placed facing each other at a predetermined interval,
In the tube inner surface inspection device, the camera holder and the light source support are connected by a spirally curved connecting body.