JPH0473103B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention generates ultrasonic waves in a conductive test material by electromagnetic action and detects the ultrasonic waves in the reverse process. This invention relates to an electromagnetic ultrasonic measuring device that performs non-contact thickness measurement and flaw detection.

[Background of the invention]

Conventionally, it has a magnet such as a DC electromagnet that generates this type of static magnetic field and a transmitter/receiver coil, and by passing a high frequency current such as a pulse current through the transmitter/receiver coil, the eddy current generated on the inner surface of the material to be examined and the static magnetic field are combined. Electromagnetic ultrasonic measurement in which ultrasonic waves are generated in the material under test due to the interaction of The device has been attracting attention as a device that can perform measurements such as thickness measurement and flaw detection of conductive materials such as metal materials without contacting the materials to be tested. In this device, the transmitter/receiver coil itself has weak mechanical strength, so it is fixed in a non-conductive storage box with resin, etc., and then attached to a predetermined position, such as between the poles of the magnet, through the storage box. It is normal to do so. However, with this conventional device, when a high frequency current such as a pulse current is passed through the transmitting and receiving coil,
Due to the interaction between the high-frequency current and the static magnetic field (DC magnetic field), the transmitting and receiving coil itself vibrates and generates ultrasonic waves.The ultrasonic waves propagate through the resin in the storage box and are reflected at the bottom of the box, causing the transmitting and receiving coil to vibrate and generate ultrasonic waves. There were drawbacks such as the detected ultrasonic noise signal becoming a hindrance to ultrasonic measurement.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electromagnetic ultrasonic measuring device that eliminates the ultrasonic noise signal from the transmitting/receiving coil storage box, which is the drawback of the prior art described above.

[Summary of the invention]

In the present invention, the transmitter/receiver coil is fixed in a non-conductive storage box with a filler such as resin mixed with a sound wave scattering agent such as fine metal powder such as tungsten oxide powder, and vibrations generated by the transmitter/receiver coil self-emission are generated inside the storage box. This is an electromagnetic ultrasonic measuring device in which the ultrasonic noise generated by the electromagnetic wave is scattered and absorbed by the above-mentioned sound scattering agent and removed.

[Embodiments of the invention]

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

FIG. 1 is a partial perspective cross section and block diagram showing an embodiment of an electromagnetic ultrasonic measuring device according to the present invention. In FIG. 1, an inverted U-shaped iron core 2 and a DC excitation coil 3 are placed facing the surface of a conductive test material 1.
A DC electromagnet consisting of the above is arranged, and a storage box 5 containing a transmitting/receiving coil 4 is attached between the poles of the iron core 2. Also, an excitation power supply 6 that supplies excitation current to the DC excitation coil 3, a pulse generator 7 that supplies high frequency current such as a pulse current to the transmission and reception coil 4, an amplifier 8 that amplifies the signal detected by the transmission and reception coil 4, and an amplifier 8 that amplifies the signal detected by the transmission and reception coil 4. A display 9 is provided which displays the ultrasonic measurement results such as the thickness of the material 1 to be inspected and flaw detection based on the output.

In this configuration, first, an excitation DC is passed through the DC excitation coil 3 from the excitation power supply 6 to excite the DC electromagnet, and a DC electromagnet ( When a high frequency current such as a pulse current is caused to flow from the pulse generator 7 to the transmitting/receiving coil 4 (shown by a dotted line), an eddy current is induced and generated on the opposing surface of the test material 1. Then, due to the interaction between the eddy current and the DC magnetic field, varying strain is generated on the surface of the material 1 to be tested, generating ultrasonic waves, which propagate within the material 1 to be tested. When the ultrasonic waves propagated in this way reflect from defects and the bottom surface of the test material 1 and return to the above-mentioned surface part of the test material 1, the change distortion caused by the ultrasonic waves and the above-mentioned direct current are generated in the reverse process. An eddy current is generated on the surface of the test material 1 due to interaction with the magnetic field,
The eddy current is detected by the transmitting/receiving coil 4 and sent to the amplifier 8.
After being amplified via the display 9, the ultrasonic measurement results such as the thickness of the material 1 to be inspected and flaw detection are displayed.

Next, FIG. 2 is a partially enlarged perspective sectional view of the storage box 5 that houses the transmitting/receiving coil 4 shown in FIG. In Fig. 2, the transmitting/receiving coil 4 is generally made of several layers of conductive wire with an outer diameter (diameter) of about 0.1 to 0.3 mm and wound several tens of times in a spiral shape. Due to its weak strength, it has traditionally been fixed in a non-conductive storage box with resin, etc., and then mounted in a predetermined position, such as between the poles of a DC electromagnet's iron core, through the storage box. On the other hand, according to the present invention, the transmitter/receiver coil 4
is fixed in a non-conductive storage box 5 with a filler such as resin mixed with a sound scattering agent such as fine metal powder such as tungsten oxide powder. That is, the transmitter/receiver coil 4 is installed at the lower part (in the figure) inside the non-conductive storage box 5, and is connected to the internal hole 1 of the storage box 5.
0 to lead wires 11 and 12 at both ends of the transmitting and receiving coil.
is being brought out. In this state, a filler such as an epoxy resin 13 mixed with a sound scattering agent such as a metal powder or a tungsten oxide powder is injected from the upper hole 10 and is dried and hardened. is fixed in place. Thereafter, it is attached to a predetermined position between the poles of the iron core 2 in FIG. 1 using the attachment hole 14 provided in the flange portion of the storage box 5.

The waveform of the detection signal of the transmitting/receiving coil 4 of FIGS. 1 and 2 with this configuration is illustrated in FIG. 3. In other words, when a high frequency current such as a pulse current is passed through the transmitting/receiving coil 4 shown in FIGS. Sound wave storage box 5
The transmitting wave T from the transmitting/receiving coil 4 and the test material detected by the transmitting/receiving coil propagate through the filling material such as resin inside and are reflected from the back surface and detected by the transmitting/receiving coil 4, as shown in Fig. 3. In addition to the first and second bottom echoes B ₁ and B ₂ (defective echoes are not shown), the conventional device also detects first and second echoes BP 1 and BP ₁ from the back side of the storage box 5 of the transmitting/receiving coil 4 The waveform of BP ₂ (indicated by the dotted line in the figure) is mixed as an ultrasonic noise signal and displayed on the display 9, which interferes with ultrasonic measurement.
According to the present invention, the ultrasonic waves generated by the vibration of the transmitter/receiver coil 4 propagate through the filling material such as resin in the storage box 5, collide with the sound scattering agent such as fine metal powder such as tungsten oxide powder mixed in, and are scattered. The waveforms of the first and second echoes BP ₁ and BP ₂ from the back of the conventional storage box 5 are displayed on the display 9 as ultrasonic noise signals. This eliminates obstacles to ultrasonic measurement and greatly improves performance.

In the above embodiment, a DC electromagnet is used to generate the magnetic field, but a permanent magnet may also be used, and in that case, an excitation power source is not required. In addition, the configuration of the iron core and DC excitation coil that make up the DC electromagnet is also the first.
It is not limited to what is illustrated in the figure. Moreover, although the transmitting and receiving coil is described as being integrated and used for both purposes, a coil consisting of two coils, a transmitting coil and a receiving coil, may also be used, and the shape of the coil is not limited to a specific shape. Furthermore, the filling material in the storage box of the transmitter/receiver coil is not limited to resin, and the sound wave scattering agent mixed in is not limited to fine metal powder such as tungsten oxide powder, but also a fine powder sound scattering agent that has a sound scattering effect. That's fine.

As described above, according to this embodiment, the transmitter/receiver coil is fixed in the storage box using a filler such as epoxy resin mixed with a fine sound scattering agent such as a fine metal powder such as tungsten oxide powder. As a result, ultrasonic noise generated within the storage box due to the vibration of the transmitter/receiver coil itself can be scattered, absorbed, attenuated, and removed.

〔Effect of the invention〕

As described above, according to the electromagnetic ultrasonic measuring device of the present invention, it is possible to easily and sufficiently remove ultrasonic noise caused by the high-frequency vibration of the transmitting and receiving coil itself, which was a drawback of conventional devices. Measurability can be greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a partial perspective cross section and block diagram showing an embodiment of the electromagnetic ultrasonic measuring device according to the present invention, and FIG.
The figure is a partially enlarged perspective sectional view of the storage box portion of the transmitting/receiving coil shown in FIG. 1, and FIG. 3 is an operational waveform diagram. 1... Test material, 2... Iron core of DC electromagnet, 3...
...Same DC excitation coil, 4...Transmission/reception coil,
5... Storage box, 6... Excitation power supply, 7... Pulse generator, 8... Amplifier, 9... Display, 10... Upper hole, 11, 12... Lead wire, 13... Ultrasonic scattering Filling material mixed with agent.

Claims (1)

[Scope of Claims] 1. It has a magnet that generates a static magnetic field and a transmitter/receiver coil, and when a high-frequency current is passed through the transmitter/receiver coil, an eddy current generated in the specimen material and the static magnetic field in the specimen material are combined. In an electromagnetic ultrasonic measuring device that generates ultrasonic waves in the material being tested through the interaction of An electromagnetic ultrasonic measuring device that is fixed with a filler containing a scattering agent. 2. The electromagnetic ultrasonic measuring device according to claim 1, wherein the sound wave scattering agent is made of fine metal powder. 3. The electromagnetic ultrasonic measuring device according to claim 2, wherein the metal fine powder is made of tungsten oxide powder. 4. The electromagnetic ultrasonic measuring device according to claim 1, wherein the filler is made of resin.