JPH0560083B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a pipe inner surface flaw inspection device using light.

[Prior art]

Conventionally, pipe cameras and other pipe inspection devices have been devised for relatively large-diameter pipes, such as communication cable pipes and water supply pipes.
It is commercially available. As shown in Fig. 2, this is a system in which a television camera 3 is attached to the tip of a push rod 2, the image of the television camera 3 is transmitted via a cable 4, and the image is displayed on an external monitor 5. . The pipe camera constructed in this manner is inserted into the pipe line 6 to detect and inspect abnormal points within the pipe line including the inner surface of the pipe line, thereby making it useful for maintenance.

Furthermore, the diameter is a little smaller, with an inner diameter of more than 10 mm.
When inspecting the inside of a pipe, a fiberscope may be used.

However, both the pipe camera and the fiberscope require illumination means and cannot be made smaller in diameter, so they cannot be inserted into small-diameter pipes with an inner diameter of 10 mm or less. An additional drawback is that it is expensive.

[Purpose of the invention]

In view of the above problems, it is an object of the present invention to provide a low-cost pipe inner surface flaw inspection device that can inspect the inner surface of a pipe with a small diameter of 10 mm or less, which has conventionally been impossible to inspect.

[Structure of the invention]

In order to achieve the above object, the pipe inner surface flaw inspection device of the present invention is a pipe inner surface flaw inspection device that is inserted into a pipe, shines a constant amount of light onto the pipe inner surface, and inspects the inner surface of the pipe for flaws by changing the amount of reflected light. The pipe inner surface flaw inspection apparatus includes a light emitting optical fiber having a light emitting source at one end, a light receiving optical fiber having a light receiving element at one end, and a light emitted through the light emitting optical fiber to the inner surface of the pipe. a first mirror that reflects the light toward the pipe; a second mirror that reflects the light reflected by the first mirror and then reflected on the inner surface of the pipe so that the light is received by the light-receiving end face of the light-receiving optical fiber; a lens that is provided between the light output end face of the light output optical fiber and the first mirror and forms an image of the light output end face of the light output optical fiber on the light reception end face of the light reception optical fiber; and the light output light It is characterized by comprising a fiber, an optical fiber for light reception, a first mirror, a second mirror, and support means for positioning the lens.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of the invention. As shown in FIG. 1, the pipe inner surface flaw inspection device of the present invention uses a light emitting optical fiber 10 having a light emitting source (not shown), such as a He-Ne laser, attached to one end. The light 12 emitted through the light-receiving optical fiber 11 having a light-receiving element (not shown) such as a PIN diode at one end and the light-emitting optical fiber 10 is transferred to the pipe 13 which is the object to be inspected. a first mirror 14 that reflects the light so as to be incident on the pipe inner surface 13a at an incident angle of 45°, for example;
First reflected light 1 reflected by the first mirror 14
a second mirror 17 that reflects a second reflected light 16 obtained by reflecting the second reflected light 16 obtained by the second reflected light 16 obtained by the second reflected light 5 reflected again at the inspection point A on the inner surface of the pipe 13a, so as to cause the light receiving end face 11a of the light receiving optical fiber 11 to receive the second reflected light 16; is provided between the light emitting end face 10a of the optical fiber 10 for light emitting and the first mirror, and images the light emitting end face 10a of the light emitting optical fiber 10 on the light receiving end face 11a of the light receiving optical fiber 11. For example, a graded index type lens 18 whose refractive index decreases smoothly in the radial direction, and the optical fiber 1 for light output.
0, optical fiber 11 for light reception, first mirror 14,
It consists of a supporting means 20 that positions the second mirror 17 and lens 18 at predetermined positions and covers and protects them. In addition, when the support means 20 has a sleeve shape that covers and protects the entire support means 20 as shown in FIG. Windows 21 and 22 are provided so as not to block light.

A pipe inner surface inspection method using the pipe inner surface flaw inspection apparatus of the present invention will be described. First, a constant amount of laser light emitted by a light emitting source (not shown) is passed through the light-emitting optical fiber 10 to the light-emitting end face 10 of the light-emitting optical fiber 10.
Light is emitted from a. This light passes through a lens 18 provided so that the light-emitting end face 10a of the light-emitting optical fiber 10 forms an image on the light-receiving end face 11a of the light-receiving optical fiber 11, and is directed to the first mirror 14 as light 12. incident. This first mirror 14 is arranged so that when the pipe inner surface flaw inspection device of the present invention is inserted parallel to the axis of the pipe 13, the first reflected light 15 reflected by the first mirror 14 is incident on the pipe inner surface 13a.
It is attached to the support means 20 at an angle of 67.5 degrees with respect to the axial direction, that is, with respect to the optical axis of the light beam 12, so that the light beam is incident at an angle of 45 degrees. The first reflected light 15 reflected by the first mirror 14 is reflected again by the inner surface 13a of the pipe, becomes the second reflected light 16, and enters the second mirror 17. This second mirror 17 is fixed to the support means 20 in an axial direction, that is, at an angle of 22.5 degrees with respect to the optical axis of the light 12, so that the second reflected light 16 is
2, at least the light receiving end surface 11a thereof
It enters an optical fiber 11 for light reception, which is supported and fixed in parallel nearby. The light is then received by a light-receiving element such as a PIN diode attached to one end of the light-receiving optical fiber 11 via this light-receiving optical fiber 11. Therefore, if there are scratches or corrosion at the inspection point A on the inner surface of the pipe 13a, a portion of the first reflected light 15 will be scattered at the inspection point A, resulting in a decrease in reflectance and a loss of light receiving optical fiber. 2nd reaching 11
The amount of reflected light 16 decreases. Therefore, by monitoring the amount of reflected light returning to the light receiving element while emitting a constant amount of light from the light emitting source, it is possible to detect scratches or corrosion on the inner surface of the pipe from changes in the amount of received light.

Note that it is not necessary to limit the incident angle of the first reflected light 15 to the pipe inner surface 13a to 45°. Further, as the optical fiber 11 for light reception, it is convenient to use a bundle fiber made by bundling a plurality of optical fibers in order to widen the light reception end face 11a and facilitate light reception. Furthermore, the image of the light emitting end face 10a of the light emitting optical fiber 10 is formed on the light receiving end face 11a of the light receiving optical fiber 11 using the lens 18. This is to increase sensitivity.

According to the pipe inner surface flaw inspection device of the present invention, unlike conventional pipe cameras and fiberscopes, it does not require an illumination means, so it can be made smaller and smaller in diameter. It can be inserted into diameter pipes and inspects for scratches on the inner surface. Furthermore, since no imaging means is required, it is inexpensive. In addition, since optical fiber is used, it can be made longer.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to inspect the inner surface of a pipe with a small diameter of 10 mm or less, which was impossible to inspect conventionally, and to obtain an inexpensive pipe inner surface flaw inspection device.

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged longitudinal cross-sectional view showing an embodiment of the pipe inner surface flaw inspection device of the present invention, and FIG. 2 is a schematic diagram showing an example of the use of a pipe camera, which is one of the conventional techniques. 10... Optical fiber for light output, 11... Optical fiber for light reception, 13a... Inner surface of pipe, 14...
First mirror, 17...second mirror, 18...lens, 20...supporting means.

Claims (1)

[Claims] 1. A pipe inner surface flaw inspection device that is inserted into a pipe and inspects flaws on the inner surface of the pipe based on changes in the amount of reflected light while shining a constant amount of light onto the inner surface of the pipe, the pipe inner surface flaw inspection device having a light emitting source at one end. An optical fiber for emitting light, an optical fiber for receiving light having a light receiving element at one end, a first mirror that reflects the light emitted through the optical fiber for emitting light toward the inner surface of the pipe, and the first mirror. a second mirror that reflects the light that has been reflected and subsequently reflected on the inner surface of the pipe so as to be received by the light receiving end face of the light receiving optical fiber; and a light emitting end face of the light emitting optical fiber and the first mirror. a lens provided between the lenses for forming an image of the light-emitting end face of the light-emitting optical fiber on the light-receiving end face of the light-receiving optical fiber; the light-emitting optical fiber; the light-receiving optical fiber; a first mirror; and a second mirror. and a support means for positioning the lens.