JPS58129250A - Ultraosonic sensor for flaw detection of small tube - Google Patents

Abstract

PURPOSE:To reduce flaw detecting time and the size of a device by providing a member which changes the transmitting and receiving routes for ultrasonic waves and a centering mechanism. CONSTITUTION:Ultrasonic waves are transmitted and received in parallel to the central axis of a small tube 18 by means of a disclike ultrasonic oscillator 11. The transmitting and receiving routes of the ultrasonic waves are changed by the tapered part of a wedge 14, and assume the angles in prescribed diagonal directions with respect to the tube 18 so that the entire circumference of the tube 18 ultrasonically detects flaws without rotating the sensor or the tube 18. On the other hand, a centering mechanism 16 formed with many rectangular striplike leaf springs is provided in an insertion tube 15 behind the oscillator 11, a damper 12 and a casing 13, by which the respective central axes of the sensor and the tube 18 are aligned automatically. By such constitution, the ultrasonic sensor for flaw detection of small tubes by which the flaw detecting time and the size of the constitution can be reduced is obtained.

Description

[Detailed description of the invention] The present invention relates to improvements in ultrasonic sensors for thin tube flaw detection.

Conventionally, ultrasonic flaw detection of thin tubes has been carried out by, for example, an oblique angle flaw detection method as shown in FIG.

In the figure, reference numeral 1 is a thin tube through which the liquid 2 of the underwater oil field passes, and an ultrasonic sensor 3 is inserted into this thin tube 1. Flaw detection in the capillary tube 1 involves transmitting ultrasonic waves from the ultrasonic sensor 3 as shown by the broken line in the figure, propagating them through the capillary tube 1, reflecting them by defects (not shown) in the capillary tube 1, and returning the waves in the opposite direction. This is done by receiving the incoming ultrasonic waves and processing them with an electric circuit (not shown).

However, in order to perform flaw detection on the entire surface of the thin tube 1 using the method described above, it is necessary to operate the ultrasonic sensor 1 or the thin tube 1 while rotating the ultrasonic sensor 3 or the thin tube 1t.

For this reason, the inspection time becomes long, it is difficult to apply this method to inspections during the service period, and the scale of the apparatus becomes large.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an ultrasonic sensor for capillary flaw detection that can reduce the inspection time and downsize the device.

Embodiments of the present invention will be described below with reference to FIGS. 2 and 3.

Reference numeral 11 in FIG. 2 is a disk-shaped ultrasonic transducer.

A mantle 73 is closely attached to the rear surface of the ultrasonic transducer 11. These ultrasonic transducers 11 and /7 are
The circumferential surface of IJ and a portion of the casing 131C are surrounded by the casing 131C.

A nine-cone-shaped wedge 14 is disposed on the front surface of the vertical ultrasonic transducer 11 so that the front l111I is in the shape of a chi, and the central axes of the wedges 14 are made to coincide with each other. One end of an insertion tube 15 is inserted into the rear part of the casing 13, and an alignment mechanism IC having a large number of strip-shaped leaf springs on the periphery of both ends is attached to the insertion tube 15.

K, which performs ultrasonic flaw detection of thin tubes using the above-mentioned ultrasonic sensor, first uses water or oily liquid 1 as shown in Figure 3.
7 is filled in the thin tube 18, and the ultrasonic sensor is aligned W&J 6 (not shown in Figure 3). While aligning the axis, insert the insertion tube 11 (not shown for the third factor).
Next, an electric circuit (not shown) causes the ultrasonic transducer 1 to generate ultrasonic waves that pass parallel to the central axis of the thin tube 18. For example, the ultrasonic wave propagates through the wedge 14 through the path shown by the broken line in the figure, is refracted at the slope of the wedge 14, and
In the liquid 17 Here, the apex angle θ1 of the wedge 14 is set so that the incident angle α of the ultrasonic wave on the thin tube 18 is an angle that can generate a Lamb wave in the thin tube 18. The relationship with is shown by the formula below.

Cc: Sound velocity in liquid Ir Cw: Longitudinal sound velocity in wedge 14 For example, when wedge 14 is crown glass and liquid 17 is water, Cc-1500TV/s, Cyz5660
Vs, and if #1 is set to 20°, α1±34.4
' becomes. This is the angle of incidence at which Lamb waves such as Mu-Mo can be generated in a steel thin tube with a wall thickness of 1.5 mm using ultrasonic waves having a frequency of I MHS Ii degrees.

The Lamb wave propagates through the thin tube 18 as shown by the wavy line in Fig. 3,
If there is a defect within the range that this Lamb wave can reach,
reflected by the defect. The waves then propagate through a course opposite to the above-described course, are received by the ultrasonic transducer 11, and are processed by an electric circuit (not shown) to detect defects in the thin tube 18.

According to the present invention, Lamb waves can be generated all around the circumference of the capillary tube Ig, and since they are only slightly absorbed by the liquid 11, there is little attenuation. There is no need to rotate the ultrasonic sensor 11 or the thin tube 18, and it is possible to detect defects within the range reached by Lamb waves with low attenuation. As a result, the inspection time can be significantly shortened, it can be applied to inspections during the service period, and the device can also be small.

Incidentally, the ultrasonic sensor for capillary flaw detection according to the present invention is not limited to the one shown in FIG. 2, but may be the one shown in FIG. 4 or FIG. 6.

That is, 11 in FIG. 4 is a disc-shaped ultrasonic transducer. An IF/4-12 is closely attached to the rear surface of the ultrasonic transducer 11. These ultrasonic transducers 1 and Dan Zu
The peripheral surface of 17 and a part of the rear part of 12 are covered by the casing. The ultrasonic transducer 1
A substantially conical acoustic mirror 19 is disposed on the front surface of the mirror 1 so that its slopes face each other and their central axes coincide with each other. One end of an insertion tube 15 is inserted into the rear part of the casing 1j. An alignment mechanism 161 having a large number of strip-shaped leaf springs on the periphery is fitted into this insertion tube 1j, and a similar alignment mechanism 15 is inserted into the #J surface of the thread 11<chi 19. ing.

KFi conducts ultrasonic flaw detection of thin tubes using the above-mentioned ultrasonic sensor. First, as shown in FIG. (not shown in FIG. 5) Therefore, the central axis of the ultrasonic transducer 11 and the acoustic mirror 19 and the thin tube 18
While aligning the center axis of the insertion tube 15 (5th tjAK
(not shown), the ultrasonic transducer 11 transmits ultrasonic waves traveling parallel to the central axis of the thin tube 11 by an electric circuit (not shown). For example, the ultrasonic wave propagates through the liquid Ir through the path indicated by the broken line in the figure, and then passes through the acoustic mirror 19.
Reflected on #1 side of , 1! The liquid 17 passes through the capillary tube 18.
reach.

Here, the apex angle #of the acoustic mirror 1g is set so that the incident angle α1 of the ultrasonic wave on the thin tube 18 is an angle that can generate a Lamb wave in 1iavll, and the relationship between θ and α3 is is shown by the formula below.

α, = 90° -- For example, if θXue -73.8°, α, = 16.2°, which means that if ultrasonic waves with a frequency of tMHI 1m degrees are used, the wall thickness will be 1.2cm. This is an incident angle that can generate an 8o mode Lamb wave in a steel tube. In this way, defects in the capillary tube Il can be detected in the same manner as in the embodiment described above.

Further, numeral 11 in FIG. 6 is a disc-shaped ultrasonic transducer. A Danzaku-12 is closely attached to the rear surface of the ultrasonic transducer 11. The peripheral surfaces of these ultrasonic transducers 11 and Dan/#-1j, and a portion of the rear of Dan/#-13 are surrounded by a casing 11. A wedge j0 is disposed on the front surface of the ultrasonic transducer 11, which has a front II-shaped f-shape and has a conical concave portion at the front. This wedge 20
A conical acoustic mirror 21 is fitted into the front recess. These ultrasonic transducers IJ.

The wedge 20 and the acoustic i-chie 21 are arranged so that their central axes coincide. One end of an insertion tube 15 is inserted into the rear part of the casing 13. A centering mechanism 161 having a large number of plates and ribs is fitted around the insertion tube 15, and a tube body 22 inserted into the front surface of the acoustic mirror 21 is fitted into the insertion tube 15.
A similar alignment mechanism 164 is inserted in the .

Ultrasonic flaw detection of a thin tube using the above-mentioned ultrasonic sensor is carried out by the same operation as in the embodiment described above, as shown in FIG.

Ultrasonic waves generated from point a of the ultrasonic transducer 11, for example, and proceeding parallel to the central axis of the thin tube II, propagate through the wedge 20, as shown by the broken line in the figure, and are emitted at point b on the slope of the acoustic mirror 21. The light is bent at eight points on the outer peripheral slope of the wedge 20, propagates through the liquid 11, and reaches four points on the thin tube 18.

Here, acoustic mirror 11 (D apex angle 0s and acoustic mirror 2
The angle Js formed by the slope of 1 and the slope of wedge 20 is
The incident angle α1 of the ultrasonic wave is set to an angle that can generate Lamb waves in the thin tube 18. For example, if the wedge 20 is made of acrylic resin and the liquid 17 is water, Il = 73.8
', then α = 16.2°9, which is IMH
If the frequency of Tsuta AM is used, it will be possible to
This is the incident angle that can generate a 0-mode Lamb wave.

By applying such pressure, defects in the capillary can be detected in the same way as in the previous embodiment.

As described in detail above, according to the present invention, it is possible to provide an ultrasonic sensor for thin tube flaw detection that can shorten the inspection time, can be applied to inspections during service life, and can be made smaller in size.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing a conventional angle angle flaw detection method, Fig. 2 is a cutaway cross-sectional view showing an ultrasonic sensor for capillary flaw detection according to the embodiment KjP of the present invention, and Fig. 3 is a diagram showing a capillary flaw detection in an embodiment of the present invention. Explanatory diagram of the ultrasonic flaw detection method using an ultrasonic sensor, Part 4
6 and 6 are cutaway sectional views showing ultrasonic sensors for thin tube flaw detection according to other embodiments of the present invention, respectively, and FIGS. 5 and 7 are ultrasonic waves for thin tube flaw detection shown in FIGS. 4 and 6, respectively. It is an explanatory view showing an ultrasonic sensor using a sensor. 11...Ultrasonic vibrator, 12...Danno parable-111
...Casing, 14.10...Wedge, 11...
・Insertion tube, 11.16 ㇰ *1g1.16@ *1i
4... Alignment mechanism, 1r... Liquid, 18... Thin tube,
III. 21... Acoustic mirror, 22... Tube body. Applicant's sub-agent Patent attorney Takehiko Suzue 2 figures 3111 417 4 figures 5 figures

Claims (1)

[Claims] A disc-shaped ultrasonic transducer that is inserted into a thin tube and transmits and receives ultrasonic waves that travel parallel to the central axis of the thin tube, and a path of the ultrasonic wave t.
1. An ultrasonic sensor for thin tube flaw detection, comprising: a member for i-forming, and an alignment mechanism for aligning the center axes of these members and the center axis of the thin tube.