JPH1082769A - Adjustable focusing probe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust the position for focusing an ultrasonic wave in a member to be inspected arbitrarily by adjusting the movement of an acoustic lens in a state where a constant distance is kept between a probe and the member to be inspected. SOLUTION: To the adjustable focusing probe body 2, a probe holder 3 and a probe 4 are fixed and an acoustic lens 5 having variable distance to the front of the probe 4 is disposed in front of the probe 4 while being positioned with respect to the variable focusing probe body 2 by means of a spring 6 and an adjusting screw 7. The acoustic lens 5 can be moved by adjusting the screw 7. Consequently, when a flaw is detected in the vicinity of a welded part by inserting the probe 4 into a nozzle, e.g. a small caliber nozzle 1, the position for focusing ultrasonic wave in the member to be inspected can be adjusted easily and arbitrarily and thereby defect detection performance can be enhanced. Furthermore, an efficient flaw detection can be realized because the defect signal position on a flaw detection waveform is invariant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a probe used for an ultrasonic flaw detector.

[0002]

2. Description of the Related Art The prior art is shown in FIGS. FIG.
FIG. 4 is a cross-sectional view showing a flaw detection situation for a mounting weld portion 21 of a conventional small-diameter nozzle 1.

FIG. 4 is a cross-sectional view showing the state of propagation of an ultrasonic beam at the time of flaw detection, which is directed to the mounting weld portion 21 of the conventional small-diameter nozzle 1. As a non-destructive inspection method for the pressure vessel 20 and the like, there is a method using ultrasonic waves.

[0004] In principle, it consists of an ultrasonic flaw detector and a probe, etc., and the ultrasonic wave generated by the probe is made incident and propagated on a material to be inspected such as a pressure vessel to detect a reflected signal. By
It is intended to detect the presence of cracks and the like inside the inspection object flaw detector.

At this time, the probe has a role of transmitting and receiving ultrasonic waves. FIG. 3 shows the shape of the welding portion 21 of the small-diameter nozzle 1 installed in the pressure vessel 20 and the state of flaw detection.

[0006] The target portion of the inspection is generally the welded portion and its periphery. For flaw detection, a probe guide operation device (not shown),
The test is performed using a flaw detector (not shown) and a flaw detector configured by the probe 4 and the like.

FIG. 3 shows a case in which a probe 4 is inserted into a nozzle 1 which is a material to be inspected, and an attempt is made to detect a flaw in the portion. The ultrasonic wave transmitted from the probe 4 propagates to the material to be inspected via the propagation medium.

If a defect such as a crack exists inside the material to be inspected, the ultrasonic wave is reflected by the defect, and the ultrasonic wave propagates in the reverse path, is received by the probe, and is connected to the ultrasonic probe. The ultrasonic flaw detector detects the defect signal on the flaw detection signal waveform signal as a defect signal.

At this time, if a probe having a planar transducer which is generally used is used, the ultrasonic wave is refracted by the influence of the curvature of the surface of the material to be inspected, and the ultrasonic wave is generated near the surface. It will converge.

FIG. 4 (a) shows such a situation. The focal position 22 of the ultrasonic wave is determined by the sound speed and the shape of the constituent members, and the ultrasonic wave is diffused farther from the focal position. Due to the diffusion of ultrasonic waves, the density of ultrasonic waves decreases in the flaw detection area,
The signal reflected from the defect also decreases, resulting in a decrease in detection performance.

In order to prevent the influence of the curvature of the surface of the material to be inspected and to appropriately apply ultrasonic waves to the flaw detection area in the depth direction, as shown in an example of FIG. In addition, an acoustic lens is attached and used for the purpose of diffusing ultrasonic waves to the front of a probe having a planar transducer.

However, even in this case, the focused position of the ultrasonic wave is determined by the sound speed and shape of the components, that is, the sound speed of the ultrasonic wave propagation medium, the sound speed and the curvature shape of the acoustic lens material, and the sound speed and the curvature shape of the material to be inspected. The decision is the same as above,
The curvature conditions of the vibrator having a convex shape and the sound velocity and curvature conditions of the acoustic lens in which the ultrasonic waves are focused in the flaw detection area are set in advance and used.

[0013] These conditions are conditions for focusing at a certain position in the depth direction in the inspection material. In order to perform flaw detection over the entire range of the flaw detection region in the depth direction, a plurality of probes having different focusing regions are required. A flaw detector is required, and the flaw detection is performed by sequentially using the ultrasonic wave depending on the focusing area.

As a method of transmitting the ultrasonic waves generated by the probe 4 to the material to be inspected, there are a water immersion method in which the ultrasonic wave propagation path between the probe and the material to be inspected is filled with water as a propagation medium and flaws are detected in water. There is a direct contact method in which a probe is brought into direct contact with a material to be inspected to perform flaw detection.

In each of these methods, a dedicated probe is used. In particular, in the direct contact method, as a propagation medium, a probe having a shape matching the surface curvature of a material to be inspected made of an acrylic resin material or the like is used. A probe having a shoe installed on the front surface is used, and is used in combination with the above-described convex oscillator and an acoustic lens for diffusing ultrasonic waves.

[0016]

However, the above-mentioned conventional probe has the following problems. (1) Since the focused position of the ultrasonic wave is constant and the focused region usable for flaw detection is limited, only a part of the depth-wise inspection region around the welded portion can be flaw-detected. . (2) A plurality of probes having different convergence positions are required in order to perform a complete flaw detection in the depth direction inspection range. (3) Further, a convex oscillator requires a high manufacturing technique and is expensive as compared with a planar oscillator. An object of the present invention is to provide a probe that can solve these problems.

[0017]

[Means for Solving the Problems] (First Means) A variable focusing probe according to the present invention is a probe used for an ultrasonic flaw detector, which comprises: (A) a planar vibrator; (B) an acoustic lens (5) which is arranged on the inspection object side of the probe 4 and performs convergence and diffusion of ultrasonic waves; and (C) movement adjustment of the acoustic lens. Mechanism (6, 7), (D) probe holder (3), (E)
(F) Acoustic lens (5) with the distance between the probe (4) and the material to be inspected kept constant.
Can be moved and adjusted. (Second Means) The variable focusing probe according to the present invention
In the probe used in the ultrasonic flaw detector according to the above means, the casing (10) is characterized by having a curvature shape along the surface of the material to be inspected.

Therefore, the operation is as follows. The variable focusing probe according to the present invention is configured as described above. (1) At the time of flaw detection, the acoustic lens 5 can be moved by operating the position adjusting screw 7, so that the acoustic lens 5 can move inside the material to be inspected. The position where the ultrasonic wave is focused can be adjusted to an arbitrary position. (2) In addition, since the position of the acoustic lens 5 can be moved and adjusted while keeping the distance between the probe 4 and the material to be inspected constant, the defect signal position on the flaw detection waveform remains unchanged. Will be.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
2 to FIG. FIG. 1 is a sectional view of a variable focusing probe according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing an aspect of an ultrasonic beam of the variable focusing type probe according to the first embodiment of the present invention. FIG. 1 shows an example of a state in which the variable focusing probe of the present invention is installed on the inner surface of a small-diameter nozzle 1 to be inspected. The variable focusing probe main body 2 includes a probe. The holder 3 and the probe 4 are attached, and an acoustic lens 5 whose distance from the front of the probe is variable is installed on the front surface of the probe 4. 6 and an adjustment screw 7.

The position of the acoustic lens 5 can be moved by operating the adjusting screw 7. 2A and 2B show the state of propagation of an ultrasonic beam when the present invention is installed on a small-diameter nozzle to be inspected. FIG. 2A shows the distance between the front surface of the probe and the acoustic lens 5. 5 shows a state in which the tension screw 7 is adjusted and the focal point 9 of the ultrasonic beam 8 is set and adjusted to a short distance within the inspection object. FIG. 2B similarly shows a state in which the focus of the ultrasonic beam is set and adjusted to a far distance within the inspection object.

[0022]

Since the present invention is configured as described above, it has the following effects. (1) According to the present invention, when a probe is inserted into a nozzle such as a small-diameter nozzle and a flaw is to be detected in the vicinity of a welded portion, a position where an ultrasonic wave suitable for flaw detection is focused inside the material to be inspected. It can be easily adjusted to any position. Therefore, it is possible to contribute to improvement of the defect detection performance. (2) In addition, since the position of the acoustic lens can be adjusted while keeping the distance between the probe and the material to be inspected constant, the defect signal position on the flaw detection waveform can be maintained at a constant position. Become. (3) Therefore, owning a plurality of transducers
It is not necessary to replace the probe according to the flaw detection area, and efficient flaw detection can be realized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a variable focusing probe according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing an aspect of an ultrasonic beam of the variable focusing type probe according to the first embodiment of the present invention.

FIG. 3 is directed to a conventional small-diameter nozzle mounting welded portion;
Sectional drawing which shows a flaw detection situation.

FIG. 4 is a view showing a conventional small-diameter nozzle mounting weld portion;
Sectional drawing which shows the propagation condition of the ultrasonic beam at the time of a flaw detection.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Small diameter nozzle 2 ... Variable focusing type probe main body 3 ... Probe holder 4 ... Probe 5 ... Acoustic lens 6 ... Spring 7 ... Adjustment screw 8 ... Ultrasonic beam 9 ... Focus 10 ... Casing 20 ... Pressure vessel 21 ... Mounting weld 22 ... Focusing position

Claims (2)

[Claims] 1. A probe used in an ultrasonic flaw detector, comprising: (A) a probe (4) having a planar vibrator;
(B) an acoustic lens (5) arranged on the material to be inspected side of the probe (4) to converge and diffuse ultrasonic waves; and (C) a movement adjusting mechanism (6, 7) of the acoustic lens. , (D) a probe holder (3) and (E) a casing (10), and (F) an acoustic lens (5) with the distance between the probe (4) and the material to be inspected kept constant. The variable focusing probe is characterized in that it can be moved and adjusted. 2. The apparatus according to claim 1, wherein the casing has a curvature shape along the surface of the material to be inspected.
The variable focusing probe described.