JPH03183944A - Ultrasonic flaw detecting device for tube - Google Patents

Abstract

PURPOSE:To shorten the inspection time and to easily perform flaw detection at the bent part of a U-shaped tube by reflecting ultrasonic waves which are generated by plural ultrasonic wave generating elements by the conic surface of an ultrasonic wave reflecting mirror in mutually different directions. CONSTITUTION:An element support body 21 where plural ring-shaped ultrasonic wave generating elements 20a - 20c are arrayed concentrically with the axis of the tube 10 is mounted on the front surface of a rear sealed body, and a front sealed body 8 where an ultrasonic wave reflecting body 22 is stuck is fixed on its front surface. On the reflecting body 22, the conic ultrasonic wave reflecting mirrors 23a - 23c which differ in tilt angle are formed opposite corresponding to the respective elements 20a - 20c. Then when high-voltage pulses are applied to the elements 20a - 20c from an ultrasonic wave flaw detector 9 at constant intervals of time, ultrasonic waves are generated and propagated in the reflection body 22 to reach the reflecting mirrors 23a - 23c. They are reflected almost completely by the reflecting mirrors and propagated as an ultrasonic wave f1 perpendicular to the wall surface - a surface ultrasonic wave f3 along the internal surface of the tube. Consequently, plural (3) kinds of flaw detection are performed almost simultaneously.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to an ultrasonic flaw detection device for thin tubes used in heat exchangers and the like.

(Prior art) In general, in order to confirm the integrity of heat exchanger thin tubes installed in thermal power plants, nuclear couplants, etc., during manufacturing and during use, eddy current testing, ultrasonic testing, etc. Non-destructive testing such as testing may be conducted.

FIG. 4 is a diagram showing an example of an ultrasonic flaw detection device for measuring the wall thickness of a pipe during use.
A drive motor 4 is connected via a rear sealing body 3 having a shape. In front of the drive motor 4 is a vertical probe 5.
A sensor section 6 in which a sensor section 6 is incorporated and is rotationally driven around an axis by the drive motor 4 is connected via a slip ring 7. A front sealing body 8 having a seal ring 8a is provided in front of the sensor section 6. Further, the vertical probe 5 is electrically connected to an ultrasonic flaw detector 9 installed outside the tube via a transmission/reception line inserted into the operating shaft 2 or the like.

Therefore, when detecting flaws inside the tube 10, the sensor section 6 inserted into the tube 10 together with the front and rear sealing bodies 3, 8, etc.
While being rotated around the axis of the tube 10 by the drive motor 4, it is moved in the axial direction of the tube 10 by the drive device 1 via the operating shaft 2. As the vertical probe 5 moves in the rotational and axial directions inside the tube 10, it receives signals from the ultrasonic flaw detector 9 installed outside the tube and transmits and receives ultrasonic waves. As schematically shown in FIG. 5, the wall thickness of the tube is measured by receiving signals of multiple reflections 11 generated between the inner surface 10a and the outer surface 10b of the tube in the thickness direction of the tube 10.

FIG. 6 is a schematic diagram of the signal of the multiple reflection 11 on the cathode ray tube of the ultrasonic flaw detector, and shows the multiple reflection signals 11a, ll.
The wall thickness of the tube can be detected by converting from each time interval b and 11C.

FIG. 4 shows an example of measuring the wall thickness of a pipe using the vertical probe 5. By replacing the vertical probe with an angle probe and a surface wave probe, cracks inside and outside the pipe can be detected. It is also possible to detect cracks on the inner surface of the tube.

In addition, in order to investigate the integrity of a pipe with higher reliability, it is necessary to measure the wall thickness of the pipe, detect cracks on the inner and outer surfaces of the pipe, and detect cracks inside the pipe. To perform flaw detection, a vertical probe, an oblique probe, and a surface wave probe can be installed in a device as shown in Figure 4, and each flaw detection can be carried out, or as shown in Figure 7. , a vertical probe 5, an oblique probe 12, and a surface wave probe 13 are all required in the axial direction of the tube.

(Problem to be Solved by the Invention) However, when such a device is used to detect cracks occurring on the inner and outer surfaces of a tube or to measure the wall thickness of a tube, the device shown in FIG. Since flaw detection must be performed while sequentially replacing the angular probe and the vertical probe, there are practical inconveniences such as a longer inspection time required for all inspections.

In addition, in the device shown in Fig. 7, the surface wave probe, the angle probe, and the vertical probe are arranged in the axial direction of the tube, so the sensor section becomes long in the axial direction, and the U At the bent portion of the tube, there is a problem in that it is difficult or impossible to move the sensor portion in the axial direction of the tube due to the curvature of the bent +lb portion.

In view of these points, it is an object of the present invention to provide an ultrasonic tube flaw detection device that requires less detection time and can easily detect flaws even at bent portions of U-shaped tubes.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides a plurality of ring-shaped ultrasonic generating elements provided concentrically with respect to the tube axis, each having an inclination angle on the front surface corresponding to each ultrasonic generating element. An ultrasonic probe provided with an ultrasonic reflector having ultrasonic reflectors with different conical surfaces, a drive device for moving the ultrasonic probe in the axial direction of a tube, and the ultrasonic generating element. and an ultrasonic flaw detector that transmits and receives ultrasonic signals between the two.

(Function) When the ultrasonic probe is moved in the axial direction inside the tube by the drive device, the ultrasonic waves generated from each ultrasonic generating element are reflected by the corresponding conical surface of the ultrasonic reflector, and the ultrasonic probe is moved inside the tube in the axial direction. A plurality of ultrasonic waves with different inclinations are propagated in arbitrary directions on the inner and outer surfaces, and crack detection on the inner and outer surfaces of the tube and measurement of the wall thickness of the tube are performed according to the inclinations.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

In FIG. 1, a plurality of ring-shaped ultrasonic generating elements 20a are arranged concentrically with respect to the axis of the tube 10 on the front surface of the rear sealing body 3 with a seal ring 3a provided at the tip of the operating shaft 2.
, 20b, 20c is mounted on the element support 21, and an ultrasonic reflector 2 is mounted on the front surface of the element support 21.
2 is attached to the ultrasonic reflector 22, and a front sealing body 8 having a seal ring 8a is further fixed to the front surface of the ultrasonic reflector 22.

The ultrasonic reflector 22 includes each ultrasonic generating element 20a,
20b, 20c, and a conical ultrasonic reflection with a different angle of inclination corresponding to each ultrasonic wave generating element 20a, 20b, 20c! 23a, 23b, and 23c form a tail. The ultrasonic reflector 22 is made of acrylic resin, and includes an ultrasonic reflector 23a,
23b.

A void 24 defined by a reflective mirror surface is formed on the side opposite to the ultrasonic generating elements 20a, 20b, and 20c of 23c, and the void 24 is filled with air.

This cavity 24 is sealed by the front sealing body 8.

Other materials may be used to fill the ultrasonic reflector 22 and the void 24 as long as they have significantly different acoustic impedances and reflect ultrasonic waves at the interface between them.

In addition, the rear sealing body 3 includes front and rear seal rings 3a, 8.
A supply pipe 25 for supplying an ultrasonic propagating liquid is connected to the space within the pipe surrounded by spaces a.

Further, the actuation shaft 2 is connected to a drive device 1 outside the tube, and each ultrasound generating cord 20a.

20b and 20c are electrically coupled to the ultrasonic flaw detector 9.

Therefore, when performing flaw detection on the tube 10 with this apparatus, the ultrasonic generating elements 20a and 20b are used.

An ultrasonic probe consisting of a 20C1 element support 21, an ultrasonic reflector 22, etc. is pushed into the tube 10, and the drive device 1 moves the ultrasonic probe through the operating shaft 2 at a constant speed into the tube 10. Move in the axial direction.

In this case, the annular gap between the ultrasonic reflector 22 and the inner surface of the tube 10, which is sealed by both seal rings 3a and 8a, is filled with an ultrasonic propagation liquid via the supply tube 25, and the above-mentioned Both seal rings 3a and 8a align the axis of the ultrasonic probe with the axis of the tube 10, thereby stabilizing the movement of the ultrasonic probe.

Therefore, the ultrasonic wave generating elements 20a and 20b.

High-voltage pulses are sequentially applied to the ultrasonic flaw detector 9 at fixed time intervals to the ultrasonic generating elements 20a and 20c, respectively.
20b and 20c generate ultrasonic waves in response to the high-pressure pulses, and the generated ultrasonic waves propagate through the ultrasonic reflector 22 to the ultrasonic reflector 23a.

23b and 23c are reached.

As for the material of the ultrasonic reflector 22, as mentioned above, acrylic resin is used in this embodiment, and the gap on the back side of the ultrasonic reflector is filled with air. Acoustic impedance is 3.2X10 each
6 and (4×1010−4) It is almost completely reflected at c.

FIG. 2 is an enlarged view of the central part of the ultrasound probe, and shows the tube 10.
The ultrasonic waves generated from the central ultrasonic generating element 20a are reflected in the radial direction of the tube by the ultrasonic reflecting mirror 23a, and are propagated as ultrasonic waves f1 perpendicular to the tube wall surface. Further, the ultrasonic waves generated by the ultrasonic generating element 20b disposed in the middle are reflected by the ultrasonic reflecting mirror 23b in the middle part and propagated inside the tube as ultrasonic waves f2 with a bending angle of 45 degrees. Further, the ultrasonic waves generated by the outermost ultrasonic generating element 20c are reflected by the outermost ultrasonic reflecting mirror 23c, and then become surface ultrasonic waves f3 along the inner surface of the tube and propagate.

Here, each ultrasonic wave f2. Incident angle αl of f3 into the tube 10,
α2 is obtained from Snell's law below.

Here, αm sound velocity of two-person radiation θm two-person radiation angle αF: bending angle θF: sound speed of bending wave From equation (1), ultrasonic wave f2 with bending angle of 45°, surface ultrasonic wave f
The respective incident angles α1. α2 is α = 10',
α2-14°.

Also, the inclination angle μm, μ2. μ3 is μm-45°μ2-(90°-10°)÷2=40°μ3-(90°
−14°)÷2=38°.

0 Therefore, the ultrasonic waves generated and propagated by the combination of the central ultrasonic generating element 20a and the ultrasonic reflecting mirror 23a propagate in the cross-sectional direction of the wall thickness of the tube, and undergo multiple reflections on the inner and outer surfaces of the tube. , multiplexed and opposite ultrasonic waves are received by the ultrasonic generating element 20a, and the received signal is displayed on the cathode ray tube 9a of the ultrasonic flaw detector 9.

Also, depending on the combination of the ultrasonic generating element 20b and the ultrasonic reflecting mirror 23b arranged in the middle, the bending angle 45
Ultrasonic waves at an oblique angle of ° are generated and propagated, reflected from a crack 25 on the outer surface of the tube 10 or a defect inside the tube wall thickness as shown in FIG. Ru.

Further, the ultrasonic waves obtained by the combination of the ultrasonic generating element 20c and the ultrasonic reflecting mirror 23c disposed on the outermost side propagate on the inner surface of the tube, and if there is a defect such as a crack 26 on the inner surface of the tube, The reflected ultrasonic wave is reflected by the ultrasonic wave generator 20c via the outermost ultrasonic reflector 23c, and the received signal 1 is transmitted as an electric signal to the ultrasonic flaw detector 9. is displayed on the cathode ray tube 9a.

FIG. 3 shows an example of a received signal 27 of a crack on the inner surface of the tube, a received signal 28 of a crack on the outer surface of the tube, and two multiple reflection signals in the thickness direction of the tube, which are received by the cathode ray tube 9a of the ultrasonic flaw detector. It is a diagram.

In the above embodiment, the surface flaw detection of the tube, the inner and outer surface flaw detection of the tube, and the wall thickness measurement of the tube are performed simultaneously. You can also do this.

That is, for example, to combine oblique and vertical ultrasound waves, the innermost and middle ultrasound generators 20a in FIG.
, 20b and the corresponding ultrasonic reflecting mirrors 23a, 23b
You may also use only

〔Effect of the invention〕

Since the present invention is configured as described above, multiple types of ultrasonic flaw detection can be performed simultaneously, and there is no need to replace the ultrasonic generating element each time depending on the type of flaw detection, thereby shortening the inspection time. . (2) With the above configuration, the length of the ultrasonic probe in the axial direction can be made relatively short, and it can be easily used for flaw detection at the bent portion of a U-shaped tube.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic configuration of an ultrasonic flaw detection device of the present invention,
Fig. 2 is an enlarged explanatory view of the ultrasonic generating element and ultrasonic reflector shown in Fig. 1, Fig. 3 is a diagram showing an example of display of the received signal on the cathode ray tube of the ultrasonic flaw detector shown in Fig. 1, and Fig. 4 The figure is a schematic configuration diagram of a conventional ultrasonic flaw detection device, Figure 5 is an explanatory diagram of the operation when measuring the wall thickness of a pipe, and Figure 6 is a wall thickness measurement II! FIG. 7 is a schematic diagram of the waveform of the multiple reflection signal of j on the cathode ray tube, and is a diagram showing another embodiment of the conventional ultrasonic flaw detection device. DESCRIPTION OF SYMBOLS 1... Drive device, 2... Operating shaft, 9... Ultrasonic flaw detector, 10... Pipe, 20a, 20b,
20 c...-Ultrasonic generating element, 21... Element support, 22... Ultrasonic reflector, 23 a, 23
b, 23c ---Ultrasonic reflector, 25...
Cracks on the outer surface of the tube, 26...Cracks on the inner surface of the tube.

Claims (1)

[Claims] An ultrasonic wave generator that has a plurality of ring-shaped ultrasonic generating elements arranged concentrically with respect to the tube axis, and an ultrasonic reflecting mirror with a conical surface having a different angle of inclination corresponding to each ultrasonic generating element on the front surface of the ring-shaped ultrasonic generating elements. An ultrasonic flaw detector that transmits and receives ultrasonic signals between an ultrasonic probe provided with a reflector, a drive device that moves the ultrasonic probe in the axial direction of a tube, and the ultrasonic generating element. An ultrasonic flaw detection device for pipes, comprising: