JPS6355442A - Detecting device for internal surface shape of pipe - Google Patents

Abstract

PURPOSE:To obtain a device having which work efficiency and high measurement accuracy by providing a lens for catching an image on the whole surface of the inside peripheral surface of a pipe to be inspected, and a rotary light receiving part which is in the projection area of an image projected through said lens and rotates a photodetector in order to scan said area. CONSTITUTION:An image on the inside peripheral surface of the pipe to be inspected P is converged by a lens 26, and projected and formed in a reduced state to a rotary light receiving part 27. The light receiving part 27 is constituted by providing the photodetector 27b in one straight line shape in a radial direction, to the rotation center side from its peripheral edge part, on the surface of a disk 27a, and also, linking the center of the rotary disk 27a to a motor M. In such a way, the electric signal of the light quantity of each part in the peripheral direction of an annular image caught by the elements 27b is fetched to an output circuit 29 through a rotary connector, and outputted to a detecting device body 2 through a cable 29a. In this regard, simultaneously, the signal of a rotary encoder linked to the motor M is outputted to the body 2, and based on it, a position in the peripheral direction of a defective part, etc., is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a device for optically detecting the inner surface shape of pipes such as heat exchangers and other various types of piping, particularly the inner surface shape of small diameter pipes.

[Prior art]

In the past, various types of internal inspection devices for small-diameter pipes have been proposed, but all of them employ structures that use ultrasonic waves or light, and examples thereof are shown in Figures 6 and 7. ing. FIG. 6 is a schematic cross-sectional view of a conventional tube inner surface inspection device using ultrasonic waves, showing an ultrasonic probe 42 equipped with ultrasonic transmitting and receiving functions and a reflecting member disposed opposite to the ultrasonic probe 42. 43 is inserted into the test cannula P, water, which is an ultrasonic propagation medium, is injected into the test cannula P, and the reflection member 43 is rotated around its axis. The ultrasonic probe 42 projects an ultrasonic wave toward this, the reflection member 43 refracts the ultrasonic wave at right angles, and the ultrasonic wave is projected onto various parts in the circumferential direction of the inner peripheral surface of the tube to be inspected P. The ultrasound probe 42 receives reflected echoes from the inner and outer surfaces of the pipe P, and the data is taken out to the inspection device main body (not shown), and
It is designed to detect the inner and outer diameters, surface irregularities, deformations, etc.

FIG. 7 is a schematic cross-sectional view of a conventional optical tube inner surface inspection device, in which a light projecting section 52 and a light receiving section are arranged inside a cylindrical casing 51a, facing a window 51b formed in a part of its peripheral wall. 53
The detection head 51 is arranged in such a manner that its optical axes intersect with each other on the inner circumferential surface of the tube to be inspected.
4, and the detection head 51 is rotated and moved in the axial direction within the test cannula P using the operation shaft 54 to optically inspect the inner circumferential surface. There is.

[Problem that the invention seeks to solve]

By the way, in the case of a detection device that uses ultrasonic waves as shown in FIG. It is necessary to fill water as a medium, and water supply, wandering equipment, and water-tight sealing means for both ends of the pipe to be inspected are required, which increases the equipment cost. The sealing, water supply and drainage operations themselves are troublesome, and there are problems such as low work efficiency. On the other hand, the optical detection device shown in Figure 7 has the advantage of not using water, but on the other hand, it is necessary to rotate and move the casing 51a using the operation shaft 54, which not only makes the work itself troublesome but also reduces work efficiency. Moreover, since the inner circumferential surface of the tube to be inspected is scanned in a spiral manner, there are problems such as low reliability of detection accuracy.

The present invention has been made in view of the above circumstances, and its purpose is to provide a tube inner surface shape detection device with simple equipment, high working efficiency, and high measurement accuracy.

[Means for solving problems]

The apparatus of the present invention includes a light source in a detection head inserted into the tube to be inspected, a means for distributing and projecting light from the light source onto the inner circumferential surface of the tube to be inspected over substantially the entire circumferential surface thereof, and an inner circumferential surface of the tube to be inspected. and a rotating light-receiving section that rotates the light-receiving element to scan the image.

[Effect]

According to the present invention, images of the entire circumferential surface of the inner peripheral surface of the tube to be inspected are scanned by the rotating light receiving section and captured sequentially.

〔Example〕

Hereinafter, the present invention will be specifically explained based on drawings □ showing embodiments thereof. FIG. 1 shows a pipe inner surface shape detection device according to the present invention (
(hereinafter referred to as the device of the present invention), FIG.
A schematic enlarged plan view of the rotating light receiving section taken along line nn in the figure, in which 1 indicates a detection head, 2 indicates a main body of the detection device, and P indicates a tube to be inspected.

The detection head 1 has a casing 21 made of a corrosion-resistant material such as metal and formed into a hollow cylindrical shape with both ends closed. The detection head 1 includes a light source 22 and a first lens constituting a light projecting optical system. Second floodlight lens 2
3, 24, a cone 25 constituting a light distribution means, a lens 26 constituting a condensing optical system, a rotating light receiving section 27, etc. are arranged.

The casing 21 is provided with an annular window 21a in which a transparent body is fitted over the entire circumference in the circumferential direction over a required dimension in the axial direction on the peripheral wall of the axially intermediate portion thereof, and also in the front.

The outer side of the rear end plate is provided with attachment parts 21b, 21c, and the other ends of the support rod 3a, which has a wheel 3 attached to one end, are spaced apart from each other by approximately 120 degrees to each attachment part 21b, 2]c. A plurality of them (usually three) are fixed at a time, and when the detection head is inserted into the test tube P, the casing 21 is supported so that its axis line is approximately aligned with the axis of the test tube P. Moreover, it is configured to move within the test cannula P while maintaining this state. Further, the attachment provided on the rear end plate of the casing 21 is provided in the center of the portion 21c by penetrating it to the detection side 1.
One end of a flexible tube 4 (a metal pipe may also be used) that also serves as a driving cable for front and rear movement is connected in communication with the inside of the casing 21, and the other end extends close to the detection device main body 2. It is extended, and a cable 22a for supplying power for each drive, a cable 29a for transmitting detection data, etc. are arranged inside.

On the other hand, inside the casing 21, a cone 25 serving as a light distribution means is disposed in the center facing the inside of the annular window 21A, with its apex facing toward the tip side of the casing 21, and with its axis line aligned with the axis of the casing 21. A second annular projection lens 24 is arranged concentrically on the outer periphery of the cone 25, and a first projection lens 24 is arranged in front of the cone 25, facing the apex of the cone 25.
Light projection lens 23. A light source 22 is arranged, while a cone 2
A lens 26 and a rotating light receiving section 27 are arranged on the side opposite to the apex of 5, with their optical axes aligned on the axial center line.

As the light source 22, a laser generator, an incandescent light source, or the like is used. The light source 22 is electrically connected to the detection device main body 2 by a cable 22a through a light emission drive port I, and is connected via a light emission drive circuit 28 based on a continuous or intermittent light emission command signal inputted from the detection device main body 2. The emitted light is converted into a parallel light beam by the first projection lens 23, and then projected onto the cone 25 from its apex side in parallel to the axis. The cone 25 has a mirror surface on its circumferential surface, and the light incident thereon is distributed and projected from the circumferential surface in all directions perpendicular to the axis.
Further, the light is projected toward the inner peripheral surface of the tube P to be inspected via the second projection lens 24.

The second light projecting lens 24 has an annular shape, and its cross section is a convex lens shape with a required circular arc on both the inner and outer circumferential surfaces,
Its focal point is set to approximately coincide with the inner circumferential surface of the tube P to be inspected, and a narrow beam is placed on the inner circumferential surface of the tube P to be inspected while condensing the light distributed by the cone 25 in the tube axis direction. It is designed to project in a ring shape. An image of the inner circumferential surface of the tube P to be inspected is focused by a lens 26 and projected onto a rotating light receiving section 27 in a reduced scale.

The rotating light-receiving section 27 has light-receiving elements 2 on the surface of the disk 27a in a required length in the radial direction from the peripheral edge toward the center of rotation.
7b are provided in a straight line, and the center of the rotating disk 27a is connected to the motor M. Light receiving element 27b
For example, a charge coupled device or 115D is used. The length of the light receiving element 27b is shown in FIGS. 4(a) and 4(b) described later.
It includes an annular image of the inner circumferential surface of the v4P to be inspected, as shown in
And further inside.

It is set so that it can be scanned outward over a required width dimension.

Electrical signals indicating the amount of light at various parts in the circumferential direction of the annular image captured by the light receiving element 27b are sent to the output circuit 29 via the rotary connector.
is taken out to the detection device main body 2 via the cable 29a.
is output to. At the same time, a signal from a rotary encoder (not shown) connected to the motor M is outputted to the detection device main body 2, and based on this signal, the circumferential position of the defective part etc. is detected.

FIG. 3 is an explanatory image showing the positional relationship between the dimension from the axis of the tube P to be inspected to the inner peripheral surface of the tube and the dimension from the optical axis of the image projected onto the rotating light receiving section. Assuming that the axial center line and the optical axis of the lens 26 in the detection head l coincide, each position Pa on the inner circumferential surface of the tube to be inspected P from the axial center line,
Dimensions up to Pb and Pc are respectively a+ Lb+ Lc
When the light reflected from here passes through the lens 26 and reaches the rotating light receiving section 27, the positions on the rotating light receiving section 27 are respectively jla and j! from the optical axis of the lens 26. b, the point Q a + Q b t Q c is separated by 1 c.

The distances of these La, tb, Lc, etc. @1- and jl a
The following relationship generally holds true between the distance @i such as + jl b + J c.

L= -□-・l However, D: Horizontal distance from the condensing lens 26 to the detection surface F; Distance from the condensing lens 26 to the surface of the rotating light receiving section 27 Therefore, the object to be detected projected onto the rotating light receiving section 27 The image of the inner surface of the brass tube P becomes an undisturbed circular image as shown in FIG. In the concave part due to corrosion on the inner circumferential surface of the pipe P, it bulges outward as shown in a in Figure 4 (b), and rust etc. have formed and the part has a convex shape. In some areas, an inwardly concave image appears as shown in b shown in FIG. 4(b).

By measuring the degree of these concavities and convexities, the depth and height of the concave and convex portions on the inner circumferential surface of the tube P to be inspected can be detected. Of course, it is also possible to estimate various inner surface properties of the tube to be inspected l) based on the roundness of the image projected onto the rotating light receiving section 27, the amount of light at each part, etc.

In the apparatus of the present invention, as shown in FIG. 1, the detection head l is inserted from one end into the tube P to be inspected from the distal end side. In this state, the detection head 1 is held by wheels 3 attached to its rear end so that the axis of the casing 21 substantially coincides with the axis of the tube to be inspected I). Then, the flexible tube 4 is paid out and the detection head 1 is inserted.
The light emitting drive circuit 2 is continuously or intermittently passed from the detection device main body 2 to the cable 22a while moving inside the tube P to be inspected.
A light emission command signal is output to 8 to cause the light source 22 to emit light.

The light from the light source 22 is converted into a parallel light beam by the first projection lens 23 and is incident on the circumferential surface of the cone 25, from where it is distributed and projected over the entire circumferential surface of the cone, and is then projected onto the second projection lens 24. The light is focused on the inner circumferential surface of the tube P to be inspected and projected in a direction perpendicular to the inner circumferential surface of the tube P so as to cover the entire circumferential surface thereof.

The image of the inner circumferential surface of the tube to be inspected P is scanned and detected by the rotating light receiving section 27 via the lens 26, photoelectrically converted by the rotating light receiving section 27, and sent to the rotary connector and the output circuit 29. It is taken out to the detection device main body 2 through the cable 27a, and the shape of the inner circumferential surface of the tube P to be inspected is detected.

The detection mode is not particularly limited, and any conventionally known method may be adopted as appropriate.

In such an embodiment, the rotating light receiving section 27 is provided as a means for adding one image of the inner circumferential surface of the tube to be inspected P, and the image is captured by scanning with the one-dimensional light receiving element 27b. The light receiving element 27b itself can be extremely simplified, and the structure of the inspection device main body 2 can also be simplified.

FIG. 5 is a schematic cross-sectional view showing another embodiment of the present invention. The second light projecting lens 24 shown in FIG. 1 is set to form an image at a position approximately equal to the sum of the dimensions up to the inner circumferential surface, and the condensing lens 26 and rotating light receiving section 31 are mounted on the case 32. The condenser lens 26 is connected to the drive shaft of the motor M in a state in which the optical axis of the condenser lens 26 is oriented toward the light projection area on the inner circumferential surface of the tube P to be inspected, and is connected to the drive shaft of the motor M. Accordingly, the rotating light receiving section 31 scans an image of the inner circumferential surface of the tube P to be inspected. The rotating light receiving section 31 is constructed by arranging light receiving elements in a straight line on the surface of a substrate. The rest of the structure is substantially the same as the embodiment shown in FIG.

In such an embodiment, the second light projecting lens 24 can be omitted and the light projecting optical system can be simplified, and the condenser lens 24 can be omitted.
6 can be made small in diameter, which has the effect of achieving miniaturization.

In addition, in the above-mentioned embodiment, the case where both the pipe to be inspected P and the casing 21 of the detection head l are circular has been described, but the present invention is not limited to circular shapes and can be applied to various types of rectangular pipes.

In addition, in each of the embodiments described above, the detection in the pipe P to be inspected is performed by inserting and pulling out the tube 4, but the drive source of the wheel 3, the braking mechanism Needless to say, it is also possible to provide a self-propelled type in the detection unit 1.

Further, in each of the above embodiments, a cone is used as a means for distributing light over the entire circumferential direction, but the present invention is not limited to this, and for example, a bundled optical fiber or the like may be used.

Further, in the above embodiment, the light receiving element 27b has a length that can scan the inner and outer regions including the annular image, but the length is not limited to this, and the light receiving element 27b is not limited to this. Dot-like light receiving elements may be provided on the disk 27a at regular intervals so that only the outgoing portion can be detected.

〔effect〕

As described above (according to the present invention), since the light receiving element is provided with a rotating light receiving section that simultaneously projects light onto the entire circumferential surface of the inner circumferential surface of the tube and scans and captures the image, the light receiving element has an annular shape. The present invention is advantageous in that it simplifies the processing required for detection, simplifies the configuration of the detection device itself, and only requires the light receiving elements to be arranged in a line for the required length, reducing component costs. It has the following effects.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of the device of the present invention, FIG. 2 is a schematic plan view of the detection head taken along the line ■-■ in FIG. 4(A) and 4(B) are explanatory diagrams of a single light image captured by the rotating light receiving section, FIG. 5 is a schematic vertical cross-sectional view showing another embodiment of the present invention, and FIG. 6.7
The figure is a schematic cross-sectional view of a conventional device. 1...Detection head 2...Detection device main body 3...Wheel 21...Casing 22...Light source 23...
First light projection lens 24... Second light projection lens 25.
... Cone 26 ... Condensing lens 27 ... Rotating light receiving section 28 ... Light emission drive circuit 29 ... Output circuit 3
DESCRIPTION OF SYMBOLS 1... Rotating light receiving part 32... Gate P... Tube to be inspected In the drawings, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. In an apparatus for detecting the inner surface shape of a tube to be inspected by inserting a detection head movable in the axial direction into the tube to be inspected,
The detection head includes a light source, a means for distributing and projecting the light emitted from the light source over the entire circumferential surface of the inner circumferential surface of the tube to be inspected, and a means for projecting the light emitted from the light source over the entire circumferential surface of the inner circumferential surface of the tube to be inspected. A tube inner surface shape detection device comprising: a capturing lens; and a rotating light receiving section that rotates and moves a light receiving element in a projection area of the image projected through the lens to scan the image. 2. The light distributing and projecting means is a cone, and is arranged such that its apex faces the light source side, and an axial line passing through the apex is located concentrically with the tube to be inspected. 2. The tube inner surface shape detection device according to item 1.