JP2556889B2 - In-pipe inspection device - Google Patents

Description

Description: [Industrial field of application] The present invention relates to a pipe inspecting apparatus for measuring the inner surface shape of tubes for heat exchangers and various pipes.

[Prior Art] FIG. 5 is a diagram showing a configuration of a conventional in-pipe inspection apparatus disclosed in, for example, Japanese Patent Application Laid-Open No. 62-150612, in which 2 is a light source, 3 is a ring-shaped slit, and 4 is a slit. And 7 are lenses,
Reference numerals 5 and 6 are conical mirrors, 8 is a film, P is a tube to be measured, and L is a central axis of the optical system.

The in-pipe inspection apparatus shown in FIG. 5 is provided in front of the light source 2 so that the central axis of the light emitted from the light source 2 substantially coincides with the central axis of the pipe to be measured P, and the center axis is the central axis. A conical mirror 5 is emitted through a ring 3 whose circumference has a predetermined radius and is arranged in front of the ring 3 so that the center axis of the lens 4 is substantially aligned with the center axis of the pipe P to be measured. The ring pattern light is radiated to the inner surface of the pipe to be measured P by being emitted through, and an image corresponding to the ring pattern light from the inner surface of the pipe to be measured P is substantially aligned with the central axis of the pipe to be measured P. An image is obtained through the conical mirror 6 and the lens 7 which are provided so as to coincide with each other, and the image is obtained on the film 8. The depth of the hole formed in the measured pipe P is measured based on the imaged shape of the image corresponding to the captured ring pattern light.

[Problems to be Solved by the Invention] By the way, in the conventional in-pipe inspection apparatus shown in FIG. 5, since the entire circumference can be imaged at one time, the inspection efficiency is high, but only the light passing through the slit placed in front of the light source is used. Since the light intensity is weak because it uses, and because a conical mirror is used in the light receiving system,
The light collection rate is low and the detection signal output is small.

The present invention has been made in order to solve the above-mentioned problems, and the entire circumference of the inner surface of the tube can be imaged at the same time, and the in-tube inspection apparatus that obtains a high detection signal output by efficiently using the light of the light source. To provide.

[Means for Solving the Problems] In the device of the present invention, a light source and a means for distributing and projecting a light beam from the light source as a light spot array having a narrow width in the longitudinal direction of the tube to be inspected over the entire inner surface of the tube to be inspected. And a two-dimensional light receiving unit for capturing a reflected light image from the inner peripheral surface of the inspection tube.

[Operation] According to the present invention, only the portion of the inner peripheral surface of the pipe to be inspected to be inspected is irradiated with light and the conical mirror of the light receiving system is removed. Therefore, a large amount of received light and a high detection signal output can be obtained. .

[Examples] The present invention will be specifically described below with reference to the drawings illustrating the examples. FIG. 1 is a schematic view showing a mode of use of the in-pipe inspection apparatus according to the present invention. In the figure, 11 is a detection head, 12 is a detection apparatus main body, and P is an inspected tube. The detection head 11 comprises a light source 22, a light projecting lens 23 constituting a light projecting optical system, and a light distributing means in a hollow cylindrical casing 21 whose both ends are closed using a corrosion resistant material such as metal. Pyramid 2
5. Lens 26, two-dimensional image pickup device 31 that constitutes the light receiving optical system
And the like are arranged. The casing 21 is provided with an annular window 21a in which a transparent body is embedded along the entire circumference in the axial direction on the peripheral wall of the intermediate portion in the axial direction, and on the outside of the front and rear end plates, mounting portions 21b, 21c. Each of the mounting portions 21b and 21c is provided with a wheel 13 attached to one end thereof, and the other ends of the support cans 13a are fixed to each other at intervals of about 120 degrees and three detection heads 11 are inspected. When inserted into the pipe P, the axis of the casing 21 is supported so as to approximately coincide with the axis of the pipe P to be inspected, and the inside of the pipe P to be inspected can be moved while maintaining this state. Further, one end of the flexible tube 14 which also penetrates the center of the mounting portion 21c provided on the rear end plate of the casing 21 and serves as an actuator for front and rear movement of the detection head 11 communicates with the inside of the casing 21. The other end is connected to the main body of the detection device.
The cable 22a is connected to the cable 12, and a cable 22a for supplying power for each driving power, a cable 29a for reception, and the like are provided inside.

On the other hand, in the casing 21, a pyramid 25 serving as a light distributing means is arranged in the center of the casing 21 so as to face the inside of the annular window 21a, and its apex is directed toward the tip side of the casing 21, and the axial center line is the axial center of the casing 21. A light projecting lens 23 and a light source 22 are arranged in front of the apex of the pyramid 25 in a state of being aligned with the line, while light is emitted on the axial center line on the opposite side of the apex of the pyramid 25. A lens 26 and a two-dimensional light receiving element 31 are arranged with their axes aligned.

A laser device, an incandescent light source, or the like is used as the light source 22. The light source 22 is electrically connected to the detection device main body 2 by a cable 22a via a light emission drive circuit 28, and emits light through the light emission drive circuit 28 based on a light emission command signal input from the detection device main body 2 continuously or intermittently. The emitted light is converted into a light-collecting light flux by the light projecting lens 23, and then is projected onto the pyramid 25 from its apex side to the axial center line. The pyramid 25 has a peripheral surface as a mirror surface, and the light incident on the pyramid 25 is distributed and radiated in a direction determined by the incident angle and the inclination angle of the peripheral surface, and has a narrow width toward the inner peripheral surface of the pipe P to be inspected. It is projected as a light spot array. The number of surfaces of the pyramid 25 is determined by the inner surface shape measurement pitch of the entire circumference of the pipe to be inspected P. For example, if measurement at every 10 degrees is required, it becomes 36 surfaces and 36 light spots are generated. Only concentrated light is emitted, and a large detection signal output can be obtained.
The reflected light from the inner peripheral surface of the pipe to be inspected P is directly condensed by the lens 26 without passing through the conical mirror unlike the conventional device,
Data relating to the amount of received light of each part, which is projected onto the two-dimensional image pickup device 31 and is captured by the two-dimensional image pickup device 31, is read into the detection device main body 12 via the output circuit 29 and the cable 29a, and shape detection is performed.

FIG. 2 is an explanatory view showing a cross-sectional relationship between the axis of the pipe to be inspected P, the dimension up to the inner peripheral surface of the pipe, and the image projected on the rotary light receiving portion. Assuming that the line and the optical axis of the lens 26 in the detection head are aligned, the dimensions from the axis line to the light reflection positions Pa, Pb, Pc on the inner peripheral surface of the pipe P to be inspected are La, Lb, respectively. Lc, and the position on the two-dimensional image pickup device 31 when the light reflected from this reaches the two-dimensional image pickup device 31 through the lens 26 is 77a apart from the optical axis of the lens 26 by la, lb, and lc, respectively. , 77b, 77c above,
The following relationship is generally established between the distance L such as La, Lb and Lc and the distance l such as la, lb and lc.

However, D: horizontal distance from the lens to the detection surface F: distance from the lens to the surface of the two-dimensional image pickup element Therefore, the tube P to be inspected projected on the two-dimensional image pickup element 31
When the inner peripheral surface is a uniform circumferential surface without unevenness, the distance between the center of the screen and each part becomes equal and the light reflected from the inner surface becomes a uniform circle. In the concave portion where there is a corroded portion on the inner peripheral surface of the pipe P, the distance from the center of the screen becomes large as shown in a in FIG. 3B, and rust or the like occurs. In the convex portion, as the distance b from the center of the screen becomes smaller, the image becomes a distorted circle as shown in FIG. 3B. The distance calculation circuit 15 processes such an image of the light spot train. This situation will be described with reference to FIG. That is, the position P (xp, yp) of the arithmetic center (or the center of gravity) of the image is calculated by the image processing technique generally used in the past for the light spot image OS having the size of several pixels, and the calculated value is set as the design value. Set the distance l to the optical axis position O (xo, yo) that is a fixed value (2)
Calculate from the formula.

l = {(xo-xp) ² + (yo-yp) ² } ^1/2 (2) This operation is similarly performed for all the light spot images. The comparison circuit 16 inspects the inner surface shape of the pipe P to be inspected by comparing the calculated value 1 with the known inner diameter r of the pipe P to be inspected.

Thus, in such an apparatus of the present invention, the detection head 11 is inserted into the pipe P to be inspected from the tip side thereof as shown in FIG. In this state, the detection head 11 is held by the wheels 13 attached to the front and rear ends of the detection head 11 so that the axial center line of the casing 21 substantially coincides with the axial center line of the pipe P to be inspected. Therefore, while the flexible tube 14 is used to move the detection head 11 within the pipe P to be inspected, a light emission command signal is continuously or intermittently output from the detection device main body 12 to the light emission drive circuit 28 through the cable 22a, and the light source 22 is used. Light up. The light from the light source 22 is a projection lens
At 23, the light is converted into a collected light beam, is incident on the peripheral surface of the pyramid 25, is distributed and projected over the entire surface in the circumferential direction thereof, and is projected on the inner peripheral surface of the pipe P to be inspected as a light spot array.

The reflected light from the inner peripheral surface of the pipe to be inspected P is detected by the two-dimensional image pickup device 31 via the lens 26, is taken out to the detection device main body 12 via the output circuit 29, and the shape of the inner peripheral face of the pipe to be inspected P is determined. To be detected.

In the above-described embodiment, the case where the pipe to be inspected P and the casing 21 of the detection head 11 are both circular has been described, but the present invention is not limited to being circular at all and can be applied to various shaped pipes.

In each of the above-described embodiments, the detection head 11 is propelled in the pipe P to be inspected by inserting or pulling out the tube 14, but the drive source of the wheels 13 may be provided in the detection head 11 to be self-propelled. It goes without saying that it is good.

[Effects of the Invention] As described above, according to the present invention, the projection system is configured so that the projection light beam is projected only to the portion necessary for the inspection by the projection lens and the pyramid emitted from the light source. It is simple and has high light intensity, and since the light receiving portion is formed by only the lens without removing the conical mirror, there is an effect that a large detection signal output can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of the device of the present invention, FIG. 2 is an explanatory view showing the principle of detecting the inner surface shape of the tube, and FIGS. 3 (a) and 3 (b) are reflection light images captured by a two-dimensional image sensor. Explanatory diagram, FIG. 4 is an explanatory diagram showing processing of a light spot image, and FIG. 5 is a configuration diagram showing a conventional in-pipe inspection apparatus. 11 …… Detecting head, 12 …… Detecting device main body 13 …… Wheels, 15 …… Distance calculation circuit 16 …… Comparison circuit, 21 …… Casing 22 …… Light source, 23 …… Projector lens 25 …… Pyramid, 26 ... Lens 31 ... Two-dimensional image pickup device The same reference numerals in the drawings indicate the same or corresponding parts.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiaki Taniguchi 1-3-1, Nishitsurugaoka, Oi-cho, Iruma-gun, Saitama Toa Fuel Industry Co., Ltd. Research Institute (72) Kazuo Takashima, Tsukaguchi Honcho, Amagasaki, Hyogo Prefecture 8-1-1 Mitsubishi Electric Co., Ltd. Applied Equipment Laboratory (72) Inventor Keiichi Yamaguchi 8-1-1 1-1 Tsukaguchihonmachi, Amagasaki City, Hyogo Prefecture Mitsubishi Electric Corporation Applied Equipment Laboratory (56) References -150611 (JP, U) Actually opened 62-150612 (JP, U)

Claims (1)

(57) [Claims] 1. An apparatus for detecting an inner surface shape of a pipe to be inspected by inserting a detection head movable in the pipe to be inspected into the pipe to be inspected, wherein a light source and a light beam emitted from the light source are supplied to the pipe to be inspected. A light projecting unit that radiates a narrow spot light train in the longitudinal direction of the tube over the entire inner surface, a light-receiving lens that captures the entire image of the spot light train on the surface to be measured, and the above image A two-dimensional image pickup device that outputs an electric signal, and a distance calculation circuit that inputs the electric signal and calculates the distance between the center of each spot light of the spot light train and the central axis of the light receiving lens and the tube to be inspected An in-pipe inspection device comprising a comparison circuit for inspecting an inner surface shape.