JPS5920232B2 - ultrasonic probe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic emitting transducer unit, ie, an ultrasonic probe, such as an ultrasonic flaw detector or an ultrasonic flow meter.

In this type of probe, as shown in Fig. 1, a transducer 3 is attached to an oblique wedge 2 placed on a target object 1, and the ultrasonic waves emitted from the transducer 3 are transmitted through the wedge 2 to the target object. 1, the ultrasonic signal wave 4 is emitted in a pulsed manner, but at that time, a back echo 5 is generated which is reflected by the boundary surface on the target object 1.

Since this back echo 5 is reflected many times inside the wedge 2, ultrasonic pulses due to the back echo are also injected into the target object 1 each time, increasing the residual noise of the wedge and causing unnecessary pulse signals. In general, this often interferes with the detection of the ultrasonic pulse signal from the target object 1, and this unnecessary reflected wave, that is, the back echo 5 on the transmitter side must be eliminated as much as possible. As a means to attenuate this type of unnecessary waves, or back echoes, in an oblique wedge, a damper is placed in the direction and position of the back echo,
A configuration is known in which back echoes are guided to an appropriate repeating reflection type attenuation waveguide. However, with the damper method, there is no particular problem if the probe is at room temperature, but if the temperature is several hundred degrees Celsius or higher, the probe part must be made of a heat-resistant metal, and the damper effect generally cannot be expected. Furthermore, the attenuating waveguide method has drawbacks such as not being simple in shape, not being compact, and having a small number of reflections, resulting in little attenuation effect. SUMMARY OF THE INVENTION The object of the present invention is to eliminate the above-mentioned drawbacks and to provide an ultrasonic probe with high attenuation that is easy to manufacture, compact and can be well applied even in the case of metal wedges.

In order to achieve this object, the present invention configures at least the probe section from which the back echoes arrive as a laminated body of thin plates, and the wavelength of the ultrasonic wave emitted by the transducer and the It is characterized by having a large number of holes of the same order of magnitude.

FIG. 2 shows an embodiment of the present invention. The basic configuration is the same as that in FIG. 1, with reference numeral 1 representing an object, 2 an oblique wedge, 3 a vibrator, 4 a signal wave, and 5 an unnecessary reflected wave, ie, a back echo. According to the invention, the wedge 2 is provided with a number of holes 6 at the portion where the back echo 5 enters. The size of this hole 6 is selected to be on the same order as the wavelength of the ultrasonic wave from the vibrator 3. Moreover, the wedge 2 has a large number of thin plates 20, as shown in FIGS. 3 and 4.
It is constructed as a layered body, and the holes 6 are offset from each other in each sheet 20. According to the above configuration, back eco-15
In terms of the attenuation characteristics of
As the back echo 5 is repeatedly reflected, the back echo 5 is significantly attenuated, and the phase of the ultrasonic wave is disturbed by the above-mentioned diffused reflection, and the pulse energy of the back echo 5 is dispersed.

On the other hand, in terms of manufacturing technology, the size S of the wedge 2 is, for example, about 4011 on a side, but in this case, the diameter of the hole 6 should be on the same order of magnitude as the wavelength of the ultrasonic wave, considering the scattering efficiency. I have already said that it is good.

Since the wavelength of the ultrasonic waves used for this type of application is on the order of one magnification, if the bevel wedge 2 shown at 4 in Fig. 2 is a pine lock as in the conventional structure, it will have a diameter of 1 mm or less. It is necessary to penetrate a large number of holes over a length of, for example, 2011 mm or more, but it is extremely difficult to perform such hole drilling using a method such as an ordinary drilling machine, resulting in high costs. However, according to the present invention, since the bevel wedge 2 is composed of a large number of thin plates 20, there is an advantage that the drilling process can be easily performed by, for example, press working. The thickness of the thin plate 20 may also be about the same as the wavelength of the ultrasonic wave, for example, about 111 mm. The thin plates may be joined together by adhesive or by bolting. According to such a method, it is possible to freely design the position of the holes in the thin plate 20 from the viewpoint of the best damping characteristics of the back eco, and it is also extremely easy to shift the position of the holes for each sheet. As a result, the scattering direction of the back echo becomes three-dimensional, so that the scattering effect can be further increased. Of course, even if the hole positions are not shifted for each layer, it is sufficiently practical as long as one accepts that the scattering effect will decrease somewhat. FIG. 5 shows another embodiment of the invention.

In this embodiment, a laminated body 8 of a thin plate 80 having a large number of holes 6, which is constructed in the same manner as in the first embodiment, is tightened with bolts 9, and is manufactured separately from the wedge 2. 2, the laminated body 8 is tightened and fixed with bolts 10 at the position where the back eco-1 5 arrives. In this case, in order to improve the acoustic coupling between the wedge 2 and the laminated body 8, a metal foil 11, for example an aluminum foil, may be inserted between the two. In the case of this embodiment, the damping principle of the back echo 5 is the same as that of FIGS. 2 to 4, but the damping effect is reduced by the presence of the acoustic coupling section. However, since the perforation part is made separately from the wedge 2, the one shown in FIG. 5 may be more advantageous in terms of manufacturing technology. Incidentally, there is a crimping method of ultrasonic probes in which a transducer is placed directly on a target object and is pressed down with a presser block.

Even in this crimping method, a part of the ultrasonic waves from the vibrator is emitted as an unnecessary back wave (back echo) toward the presser block on the opposite side of the object, and is reflected on the opposite side of the presser block. We will move on to the vibrator side. FIG. 6 shows an example in which the present invention is applied to attenuate back-echo in such a crimping method.

That is, FIG. 6 shows an embodiment of a probe in which a vibrator 3 is fixed by crimping. 13 to the crimp plate 14
is placed on the object 1, and the vibrator 3 is crimped onto the target object 1 via the crimping plate 14 by a crimping bolt 15 and a tightening nut 16 that engages with the crimping bolt 15, thereby achieving good acoustic coupling between the two. be. The presser foot block is made of a laminated body of thin plates in which a number of holes 6 are drilled. In this structure,
In addition to the signal wave 4 that directly enters the target object 1 from the vibrator 3, an unnecessary backward wave, that is, a back echo 17, is generated that exits to the rear presser block 12 side. Therefore, again in accordance with the invention, the thin plate constituting the presser foot block 12 is provided with a number of holes 6 similar to that in FIG. By doing this, the back echo 17 is scattered and the pulse waveform is broken, and the scattering is repeated many times between the many holes 6 to form the scattered wave 18, which returns to the direction of the vibrator 3 and hits the target object 1. It is possible to eliminate unnecessary waves traveling towards the target. The diameter a of the hole 6 in each of the above embodiments is formed to have the same order as the wavelength λ of the ultrasonic wave, as described above.

In particular, it is preferable that the diameter a be approximately the same size as the wavelength λ. The reason for this is that when a/λ》1, the effect of scattering ultrasonic waves rapidly decreases, and when a/λ》1, the number of holes in a unit volume decreases, and the effect of diffuse scattering decreases. It is from. FIG. 7 shows a modification of the embodiment shown in FIG.
By dividing the pressure plate 14 side of the presser block 19 into two and bending it, the back echo 17 is reflected twice on the wall and then guided to a large number of holes 6, where it is scattered and attenuated. This presser block 19 is likewise made of a laminated body of thin plates having holes 6. FIGS. 8 and 9 show an example of how to make a hole that not only scatters unnecessary back echoes 17, but also confines them and prevents them from returning to the target object 1 as much as possible. It is something.

In the embodiment shown in FIG. 8, the distribution of the holes 6 is relatively coarse on the side near the vibrator, that is, on the entrance side of the back eco, and gradually becomes denser as it goes deeper and further away. By doing so, the component of the scattered wave 18 that returns to its original state can be reduced.

This becomes obvious if the distribution of holes is reversed; in that case, most of the waves would be reflected at the first example near the oscillator 3 and returned to the original state. In Figure 8, the opposite is true. In the embodiment of FIG.
0 is a triangle, and the apex of the triangle faces the vibrator side. By doing this, the scattered waves 11 can easily enter in the direction away from the vibrator 3, but they can easily enter in the opposite direction. It was made to be difficult to advance.

In addition to the above, the shape and distribution of the pores can be implemented in various ways.

As described above, according to the present invention, by providing a large number of holes with a size on the same order as the wavelength of the ultrasonic wave at the arrival position of the back echoes, the back echoes are scattered and the pulse force is dispersed. At the same time, the acoustic force is attenuated by increasing the number of reflections and the propagation length, and it is possible to significantly prevent back echoes from entering the target object again.

In particular, by configuring the probe as a laminated body of thin plates, it becomes easy to process small holes, and it is also possible to arrange the holes in a three-dimensional manner, resulting in an even better scattering effect.

[Brief explanation of the drawing]

Fig. 1 is a principle diagram showing the basic configuration of an ultrasonic probe, Fig. 2 is a configuration diagram showing an embodiment of the ultrasonic probe according to the present invention, and Fig. 3 is an exploded view of the bevel wedge in Fig. 2. A perspective view, FIG. 4 is a sectional view of the bevel wedge in FIG. 2 taken along line X-X, FIG. 5 is a perspective view showing another embodiment of the present invention, and FIGS. FIG. 9 is a configuration diagram showing still other different embodiments of the present invention. 1...Target object, 2...Bevel wedge,
3... Vibrator, 4... Signal wave, 5...
... Back eco 1, 6 ... Hole, 7 ...
...scattered waves, 8... stratified body, 20,80...
...thin plate.

Claims (1)

[Scope of Claims] 1. At least the probe portion where the back echo arrives is configured as a laminated body of thin plates, and on the propagation path of the back echo in the probe portion, there is a beam having a magnitude on the same order as the wavelength of the ultrasonic wave emitted from the transducer. An ultrasonic probe characterized by having a large number of holes. 2. The ultrasonic probe according to claim 1, wherein the hole passes directly through each thin plate. 3. The ultrasonic probe according to claim 1, wherein the holes are offset from each other for each thin plate. 4. In the ultrasonic probe according to any one of claims 1 to 3, the wedge for attaching the transducer is configured as a laminated body of thin plates, and the plurality of wedges are arranged on the propagation path of back echoes in this laminated body. An ultrasonic probe characterized by having a hole.