JPH01112151A - electromagnetic ultrasound probe - Google Patents

Abstract

PURPOSE:To reduce an unmeasurable range greatly by fitting a transmitting and receiving coil made of a nonmagnetic material to the slanting part of an internal pole iron core for DC magnetic field production which has the smooth slanting part. CONSTITUTION:An exciting coil 6 is excited by a DC power source to produce a DC magnetic field, which is applied to a machine 1 to be inspected. When a pulse from a pulse generator is applied to the transmitting and receiving coil 3, an eddy current is generated in the machine 1 to be inspected by electromagnetic induction and an acoustic wave is generated in the machine 1 to be inspected by the mutual operation between the DC magnetic field and eddy current. This acoustic wave is propagated in the machine 1 to be inspected and a reflected acoustic wave from a reflection source in the reverse or top surface of a material is detected by the transmitting and receiving coil 3 through the opposite operation from the acoustic wave generation. A similar acoustic wave is generated at the internal pole iron core 4. The external surface of the internal pole iron core 4 has no smooth inclination, so the acoustic wave from the machine 1 to be inspected returns and a measurement is finished before an acoustic wave from the back surface of the internal pole iron core 4 is propagated and scattered in the iron core 4 and returns.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electromagnetic ultrasonic probe that transmits or receives electromagnetic ultrasonic waves.

[Conventional technology]

Some conventional ultrasonic probes are designed to facilitate the replacement of electromagnetic ultrasonic transmitting and receiving coils, as described in Japanese Unexamined Patent Publication No. 10895/1983.

[Problem that the invention seeks to solve]

When electromagnetic ultrasonic waves are generated inside the machine under test, ultrasonic waves are also generated within the iron core. This prior art was developed for the purpose of facilitating the replacement of the transmitter/receiver coil, and did not take into consideration the sound wave noise that is reflected from the inner corners of the core by the sound waves generated within the core. (FIGS. 4 and 5) Therefore, in order to attach the transmitting and receiving coils to the core and to provide sockets for connecting the terminals of the transmitting and receiving coils, many corners are provided in the core. Since these corners are provided near the transmitter/receiver coil, as shown in Figure 6, reflected sound wave noise from the corners occurs immediately after the sound waves are generated, masks the reflected signal from the inspected material, and Thickness 8-1
The portion corresponding to 0mm could no longer be used for ultrasonic measurement.

On the other hand, the most important use of electromagnetic ultrasonic measurement is to measure corrosion and thinning of steel materials. Normally, corrosion thinning of steel materials, etc. is caused by base material thickness of 9 to 12 mm.
In most cases, a 1 m long piece is inspected to see if the thickness has decreased to about 4 to 5 cm. However, in the conventional technology, 8 to 1
This resulted in an unmeasurable range of 0nn, which was a big problem.

An object of the present invention is to significantly reduce this unmeasurable area.

[Means for solving problems]

The above object is achieved by eliminating reflected sound wave noise from the inner corners of the core.

First, when attaching the transmitting/receiving coil to the iron core, the tip of the iron core is finished with a smooth slope without providing a vertical step, and a non-magnetic material is attached to this slope by known means such as gluing. Form a coil attachment part. Since the iron core is finished with a smooth slope, there are no corners that could reflect sound waves inside the iron core.

Next, the terminals of the transmitting and receiving coils are not connected inside the core, but are connected externally, that is, on the side surface of the probe.

Therefore, there is no need for a groove in which a socket is provided for connection inside the core, and corners that reflect sound waves within the core are no longer generated due to the formation of the groove.

[Effect]

In this way, there are no corners near the transmitting/receiving coils of the iron core that can be sources of sound wave reflections, corner reflection noise does not occur, and the unmeasurable area immediately after sound waves are generated due to leakage of sound wave generation pulses. It can be reduced to only those that occur.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3. FIG. 1 is a cross-sectional view of the probe, FIG. 2 is a detailed view of the inner core with the transmitting and receiving coils omitted, and FIG. 3 is a received signal waveform diagram.

In the figure, a probe 2 is installed on a device under test 1, and a contactor 2 is connected to a transmitting/receiving coil 3. Inner pole core with smooth slope 4. A transmitting/receiving coil mounting portion 5 made of a non-magnetic material and having screw holes for transmitting/receiving coils attached to the inclined portion of the inner pole core 4 by known means such as adhesive, an excitation coil 6, and an outer pole core 7. Socket attached to the outer core8. Terminal pin 9 of the transmitting/receiving coil 3 connected to this socket. The socket 8 passes through the socket storage case 10 and the groove in the storage case 10.
Consists of external connection lines connected to.

Note that the height of the inner pole iron core 4 is sufficiently higher than the thickness of the machine to be inspected 1.

In this contact configuration, when the excitation coil 6 is excited by a DC power source (not shown), a DC magnetic field is generated, and the DC magnetic field is applied to the machine under test 1. Next, when a pulse from a pulse generator (not shown) is applied to the transmitter/receiver coil 3, the device under test 1
An eddy current is generated by electromagnetic induction, and a sound wave is generated in the device under test 1 due to the interaction between the DC magnetic field and the eddy current. This sound wave propagates inside the device under test 1, and reflects from the back surface or the material (
A reflected sound wave from a defect, etc.) is detected by the transmitting/receiving coil 3 by an effect opposite to the above-mentioned sound wave generation.

On the other hand, sound waves are generated in the inner pole iron core 4 as well.

FIG. 2 shows the propagation situation of sound waves in this inner pole iron core 4.

As mentioned above, the outer surface of the inner pole core 4 has a smooth slope, and since the inner pole core 4 is not provided with any special grooves, it propagates and scatters inside the inner core 4. By the time the sound waves from the back of the pole core return, the sound waves from the inspected device have returned and the measurement is complete. That is, during the measurement, the inner pole iron core 4
No reflected sound waves from the sensor will be detected and will not interfere with measurement.

Note that since the transmitting/receiving coil mounting portion 5 is made of a non-magnetic material, there is almost no direct current magnetic field and no sound waves are generated here, so there is no problem in providing a mounting screw hole for the transmitting/receiving coil.

〔Effect of the invention〕

According to the present invention, the sound waves generated by the inner pole core circle do not return during measurement, and therefore, the unmeasurable region of the received signal waveform is limited to those generated due to leakage of pulses when sound waves are generated. .

[Brief Description of the Drawings] Fig. 1 is a cross-sectional view of a probe according to an embodiment of the present invention, Fig. 2 is a detailed view of the inner pole iron core of Fig. 1, and Fig. 3 is a received signal of the present invention. FIG. 4 is a sectional view of a contactor of a conventional example, FIG. 5 is a detailed view of the inner pole iron core of FIG. 4, and FIG. 6 is a received signal waveform diagram of a conventional example. 2... Probe, 3... Transmitting/receiving coil, 4... Inner pole core, 5... Transmitting/receiving coil mounting part, 6... Excitation coil, 7... Outer pole core, 8...・Socket, 9... Pin of transmitting and receiving coil.
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Claims (1)

[Scope of Claims] 1. An inner pole core for generating a direct current magnetic field having a smooth slope, a transmitter/receiver coil made of a non-magnetic material attached to the slope of the inner pole core, and a mounting portion of the transmitter/receiver coil. An electromagnetic ultrasonic probe characterized by: 2. The electromagnetic ultrasonic probe according to claim 1, wherein the external connection of the transmitting and receiving coil is performed on a side surface of the outer core.