JPH11183445A - Flaw detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flaw detector which can detect a defect whose defect face is not parallel with the movement direction of the apparatus. SOLUTION: A wedge 2 comprises a slope 22. A through hole 24 is formed in one end part 23, and an arc-shaped tooth face 26 is formed on the other end part 25. A probe 4 is fixed and bonded to the slope 22. A copy jig 3 is provided with a curved surface part 32 whose radius of curvature is similar to the radius of curvature (r) on the outer surface 13 of a pipe 1 and with a mounting face 34. The wedge 2 is placed on the mounting face 34, and a mounting hole 35 is formed. The wedge 2 is attached to the copy jig 3 by a fixing screw 5, and it can be swiveled around the through hole 24. A gear 61 which is engaged with the tooth face 26 is attached, via a support base 62, to the mounting face 34 on the side of the other end part 25 of the wedge 2. The gear 61 is attached coaxially with a knob 63. A scale plate 65 is installed at the gear 61, and a swing angle (c) can be measured by the scale plate 65 and by a reference point 66.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flaw detector for detecting a defect inside a metal material or a pipe.

[0002]

2. Description of the Related Art Pipes of a nuclear power plant, a thermal power plant, or various plants, in which high-temperature fluid flows, are frequently started and stopped. The difference in thermal stress caused by
A defect may occur inside the pipe, and the pipe may be damaged.
Such defects are likely to lead to accidents,
It is necessary to prevent accidents by detecting them early and taking action. One example of this diagnostic method is the ultrasonic bevel flaw detection method.

FIGS. 6 and 7 show a conventional apparatus for oblique flaw detection of the inside of a pipe with ultrasonic waves. FIG. 6A is a partial front view, and FIG. 6B is a perspective view thereof. A wedge or shoe (hereinafter, referred to as a wedge 120) has a curved surface portion 132 having substantially the same curvature r as the outer surface 113 of the pipe 110, and has an inclined surface 122. The probe 140 transmits the ultrasonic beam 181 and the reflected echo 184 thereof.
For receiving the wedge 120, and the inclined surface 1 of the wedge 120.
22 and fixedly attached. When oblique flaw detection is performed, the wedge 120 is brought into contact with the outer surface 113 of the pipe 110, and the inner pipe is moved from the outer surface 113 of the pipe 110 while sliding the wedge 120 along the circumferential direction B of the pipe 110. Face 11
2, the ultrasonic beam 181 is incident at an oblique angle,
184 is detected.

Another conventional device is shown in FIG. FIG. 7 (a)
Is a front view, (b) is a side view, (c) is a front view of the wedge 120 ', and (d) is a side view of the wedge 120'. The wedge 120 ′ slides in the pipe axis direction A, and detects a reflected echo 184 from the defect 111 in the pipe 110.

[0005]

The reflected echo 184 is
The ultrasonic beam 181 is reflected by the defect 111 (defect echo), and becomes maximum when the ultrasonic beam 181 is perpendicular to the defect surface 114. However, the outer surface 11 of the pipe 110
3 and the curved portions 132, 132 'of the wedges 120, 120'
Means that the ultrasonic beam 181 is incident on the defect surface 114 at right angles when the defect surface 114 is not parallel to the pipe axis direction A of the pipe 110, for example. However, the reflection echo 184 became small, and it was difficult to detect the defect 111.
Further, for example, when a slight unevenness of the inner tube surface 112 (not shown) and a reflected echo 184 (interfering echo) reflected by other than the defect 111 are also detected. Similarly, flaw detection of the defect 111 becomes difficult. The present invention has been made in view of such circumstances, and has as its object to provide a flaw detection apparatus capable of detecting a defect whose defect surface is not parallel to the apparatus moving direction.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has a flaw detection wave generation detecting means for transmitting a flaw detection wave inside a flaw-detected object and detecting a reflected wave thereof. An incident angle setting means for injecting the flaw detection wave into the flaw detection object at a predetermined angle of incidence, wherein the flaw detection apparatus slides on the flaw detection object to perform flaw detection. It has movable mounting means, incident angle setting means rotatably installed on the mounting means, and rotating means for rotating the incident angle setting means.

Further, a defect detecting means for transmitting and receiving an ultrasonic beam to detect a defect of a flaw-detected object having a curvature, and changing a transmission / reception direction of the ultrasonic beam with respect to a tangential direction of the curvature of the flaw-detected object. Oblique holding means for holding obliquely, a mounting surface for the oblique angle holding means, a sliding means for sliding on the flaw-detected object, and swiveling the defect detecting means, A swing means for changing the transmission / reception direction may be provided. In other words, by providing the mounting surface for the oblique angle holding means on the sliding means and further including the oscillating means, it becomes possible to perform oblique angle flaw scanning and the like on a flaw-detected object having a curvature. Thus, the direction of transmission and reception of the ultrasonic beam can be changed by sliding the sliding means on the flaw detection object or turning the defect detection means, thereby intersecting the tube axis direction of the flaw detection object. Even for such a defect, the defect detection means can be adjusted so that the transmission / reception direction of the ultrasonic beam is perpendicular to the defect surface. Therefore, the flaw detection can be easily performed on the flaw detection target having a curvature, and the flaw can be detected without being affected by the direction of the defect surface.

[0008]

Next, an embodiment of a flaw detector according to the present invention will be described with reference to the drawings. FIG. 1 shows a front view of the overall configuration of the apparatus. This apparatus detects a defect 11 in a pipe 1 (object to be inspected) having a curvature r.
Wedge 2 as incident angle setting means, copying jig 3 as attachment means, and probe 4, flaw detector 71, personal computer 72, and display 73 forming part of flaw detection and generation means.
It is composed of Note that reference numeral 82 shown by a broken line in the drawing is the center axis of the ultrasonic beam 81 that propagates from the probe 4 as a flaw detection wave.

FIG. 2 shows a partially enlarged view of the vicinity of the pipe in the apparatus shown in FIG. FIG. 3 shows a plan view of FIG. 2 with the knob broken. The wedge 2 is rectangular in plan view, has a substantially triangular portion 21 in side view, and has an inclined surface 22. The inclination angle a is designed to be a predetermined refraction angle b at which a defect in the tube axis direction A on the inner tube surface 12 of the pipe 1 can be detected. Refraction angle b here
Is the central axis 8 of the ultrasonic beam 81 propagating inside the pipe 1.
2 is the angle formed by the normal 83 to the incident surface. A through hole 24 for the fixing screw 5 is formed at one end 23 of the wedge 2 in the height direction. The other end portion 25 of the wedge 2 has an arc shape, and a tooth surface 26 is formed on an end surface thereof. The bottom surface 27 of the wedge 1 is a flat surface.

The probe 4 has a protective case containing a transducer (not shown) that generates an ultrasonic beam 81 when a voltage is applied and generates a voltage when the ultrasonic beam 81 is received. Is fixed to the inclined surface 22. Probe 4
Transmits and receives the ultrasonic beam 81 toward the inclined surface 22 so as to be perpendicular to the inclined surface 22. The copying jig 3 has, on a bottom surface 31 thereof, a curved surface portion 32 substantially similar to the curvature r of the outer surface 13 of the pipe 1.
At 2, it comes into close contact with the outer surface 13 of the pipe 1. The copying jig 3 has a mounting surface 34 on the upper surface 33 thereof. The wedge 1 and the copying jig 3 are both made of acrylic resin.

The mounting surface 34 of the copying jig 3 is a flat surface on which the wedge 2 is mounted. A mounting hole 35 for the fixing screw 5 is formed in the mounting surface 34 so that the wedge 2
Are attached to the copying jig 3 with fixing screws 5. The wedge 2 is rotatable about the fixing screw 5 on the mounting surface 34 in the direction of arrow C (see FIG. 3). Wedge 2
The vertical line (virtual line) of the inclined surface 22 does not intersect with the center point (not shown) of the curved surface portion 32 of the copying jig 3. Therefore, the ultrasonic beam 81 is obliquely incident on the outer surface 13 of the pipe 1 and performs oblique flaw detection instead of vertical flaw detection. As shown in FIG. 3, a gear 61 that meshes smoothly with the tooth surface 26 of the wedge 2 is attached to the mounting surface 34 via a support base 62 on the other end 25 side of the wedge 2. The gear 61 is mounted coaxially with the knob 63. When the knob 63 is turned, the gear 61 rotates, meshes with the tooth surface 26, and the wedge 2 rotates. In addition, it is possible to make a turning movement by directly holding the wedge 2.

As shown in FIG. 4, a scale portion or a scale plate (hereinafter referred to as a scale plate 65) is provided on the upper surface portion 64 of the gear 61, and a reference point 66 of the scale plate 65 and the support base 62 is provided. Thus, the swing angle c (see FIG. 3) can be set or measured. Since the device is configured as described above, when the wedge 2 is swiveled with respect to the copying jig 3, the ultrasonic beam 81 from the probe 4, as shown by a two-dot chain line in FIG. The swing angle c changes. That is, the ultrasonic beam 81 is swung by the turning movement of the wedge 2. In addition, the tooth surface 26 of the wedge 2, the gear 61, the support 62, and the knob 63 constitute a part of a rotating means. In order to set or measure the swing angle c, the scale plate 65 of the gear 61 and the reference point 6
Instead of 6, for example, an encoder (not shown) or the like may be used.

Next, a procedure for detecting a defect using the present apparatus will be described. First, a contact medium (couplant) 74 is applied between the wedge 2 and the copying jig 3 and the pipe 1, so that the wedge 2 and the copying jig 3 rotate and the copying jig 3 is rotated.
And the pipe 1 is made to slide smoothly. The scanning jig 3 is scanned in parallel along the pipe axis direction A and the circumferential direction B of the pipe 1 while transmitting the ultrasonic beam 81 to detect a defect 11a along the pipe axis direction A. The ultrasonic beam 81 is applied to the defect surface 14a by parallel scanning for the defect 11a.
a can be incident at a right angle. The reflected echo 84 from the defect 11 a is sent as a signal to the flaw detector 71 electrically connected to the probe 4, the content of which is processed by the personal computer 72, and then output to the display 73. The display on the display 73 shows, as an example, the size of the received reflected echo 84 on the vertical axis and the time axis on the horizontal axis, and the defect 11a is easily detected by this display. Note that the ultrasonic beam 81 is preferably a pulse wave having a very short duration.

Generally, in the case of oblique flaw detection, the probe 4 is bonded to the incidence angle of the ultrasonic beam 81, the number of skips, and the wedge 2, while taking into account the position and inclination of the defect 11 to be detected. In this state, it is necessary to detect the defect 11 by performing swing scanning or the like and changing the incident direction (incident angle) of the ultrasonic beam. Therefore, it is necessary to perform flaw detection while changing the incident position and the incident direction so that the ultrasonic beam 81 strikes the defect surface 14 at right angles. That is, the defect 11b that is not along the tube axis direction A (the defect 11b in which the defect surface has a slope) is the ultrasonic beam 81 in the parallel scanning.
Are reflected in different directions, the reflected echo 84 'becomes very small and its detection becomes difficult.
The wedge 2 is swung so that 1 is incident on the defect surface 14b at a right angle, and the incident direction of the ultrasonic beam 81 is changed to perform swiveling scanning, pendulum scanning, and the like. Further, while operating the wedge 2 with the knob 63, the copying jig 3 is scanned in the tube axis direction A or the circumferential direction B to detect a defect.

Since the ultrasonic beam 81 has directivity,
By changing the direction with the knob 63, the size of the reflected echo 84 from the defect 11 also changes, but when the reflected echo 84 is maximized, the ultrasonic beam 81 is incident on the defect surface 14b at right angles. Can be determined. Therefore, the swing angle c obtained by the scale plate 65, the encoder, and the like.
, The inclination of the defect 11b is measured, the size of the defect 11b is estimated based on the size of the reflected echo 84, and the incident point 85 (based on the time difference from the transmission of the ultrasonic pulse 81 to the reception of the reflected echo 84). 2) and the defect 11b can be calculated. As described above, by using the probe 4 that can be swung, not only the defect in the tube axis direction A or the circumferential direction B but also the defect 11b having an inclination can be detected with high sensitivity. Further, since the swing angle c can be freely set by the gear 61, there is no need to manufacture and arrange a plurality of wedges 2 having different angles, which is economical. In addition, the present apparatus is capable of performing a rough flaw detection for checking for the presence or absence of a defect 11 that is not along the pipe axis direction A,
It can be used for any of the precision flaw detection for measuring the position and the like.

Although the pipe having the curvature has been described, the present invention is not limited to the pipe, and the curved portion 32 of the copying jig 3 may be adapted to the curved surface even when the flaw detection target has a curved surface. Thus, the present invention can be applied. Further, in the present apparatus, transmission and reception of ultrasonic waves are performed by one probe 4, but the present invention is not limited to this, and transmission and reception are separately performed by two.
It can also be performed using one probe.

[0017]

According to the present invention, the transmitting / receiving direction of the flaw detection wave can be changed by sliding the mounting means on the flaw detection object or turning the flaw detection wave detection means. Even for a defect that intersects the flaw detection moving direction of the flaw detection object, the flaw detection wave generation detecting means can be adjusted so that the direction of transmission and reception of the flaw detection wave is perpendicular to the defect surface. Therefore, even if the flaw detection target has a curved surface, the flaw detection can be easily performed, and the flaw can be detected without being affected by the direction of the defect surface.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of the overall configuration of a device.

FIG. 2 is a partially enlarged front view of the vicinity of a pipe in the apparatus of FIG.

FIG. 3 is a plan view of FIG. 2 with knobs cut away;

FIG. 4 is a perspective view showing a meshing state between a tooth surface of a wedge and a gear in FIG. 2;

FIG. 5 is a diagram illustrating a state in which an ultrasonic beam is reflected by a defect in a pipe, and illustrates a case where a defect surface is along the tube axis direction and a case where the defect surface is not along the tube axis direction.

FIGS. 6A and 6B are views showing a conventional apparatus, wherein FIG. 6A is a front view partially showing the apparatus, and FIG. 6B is a perspective view thereof.

7A and 7B are views showing a conventional apparatus, wherein FIG. 7A is a front view, FIG. 7B is a side view, FIG. 7C is a front view of a wedge, and FIG.
Is a side view of the wedge.

[Explanation of symbols]

 Reference Signs List 1 pipe 11 defect 2 wedge 22 inclined surface 26 tooth surface 3 copying jig 32 curved surface portion 34 mounting surface 4 probe 5 fixing screw 61 gear 62 support 81 ultrasonic beam 84 reflected echo c swing angle

Claims (1)

[Claims] 1. A flaw detection wave generation detecting means for transmitting a flaw detection wave into a flaw detection object and detecting a reflected wave thereof, and setting an incident angle at which the flaw detection wave is incident on the flaw detection object at a predetermined incident angle. Means for detecting a flaw by sliding on the flaw-detected object, the mounting means slidable on the flaw-detected object, and an incident angle setting rotatably installed on the mounting means. A flaw detection device, comprising: means for rotating the incident angle setting means.