JPS5922181B2 - Low-temperature onset method Oyobi Souchi - Google Patents

Description

Detailed Description of the Invention [0003] The present invention relates to an ultrasonic measurement method and device in which ultrasonic waves, which have been transmitted in advance to an ultrasonic transmitter having a conductive surface in a conventional manner such as a piezoelectric transducer, are transmitted electromagnetically and non-contactingly to a measurement object having a conductive surface, and the ultrasonic waves in the measurement object are detected by the reverse process described above.

Conventionally, when transmitting and detecting ultrasonic waves for the purpose of inspection or the like for metallic materials, it was necessary to bring a piezoelectric vibrator or the like into contact with the material via a contact medium such as water or oil to achieve acoustic coupling. For this reason, conventional methods were difficult to apply to high-temperature materials or materials with rough surfaces. Therefore, if it were possible to transmit and detect ultrasonic waves completely without contacting the material (object of measurement), it would be of great industrial value. However, such ultrasonic transmission and reception methods are already known for conductive materials, and details of these methods are described in Japanese Patent Publication No. 4 (Showa 4).
The principle of generating ultrasonic waves by this technique is to place a coil on a conductive material,
A changing magnetic field such as a pulsed magnetic field is applied to the conductive material to generate a mechanical wave, and the detection uses the reverse physical phenomenon described above.
In the case of the 1990-24867 publication, the coil must be placed close to the conductive material, so if it is to be used with conductive materials that are very hot, the coil must be heat resistant. Also, if it is to be used with materials that have very rough surfaces,
When the coil and the material are in frequent contact with each other, it is necessary to make the coil mechanically strong. Therefore, if it is possible to penetrate ultrasonic waves into the material without contact and to detect ultrasonic waves in the material without contact, without using a composite structure such as a coil,
This enables non-contact ultrasonic measurement that is heat-resistant and mechanically robust and stable, and is of enormous industrial value.

In this sense, the present invention provides an effective solution to the shortcomings of the conventional methods.

In the present invention, ultrasonic waves generated in an ultrasonic transmitter having a conductive surface in advance by a conventional method are electromagnetically and non-contactly transmitted to a material having a conductive surface to be measured,
The present invention also provides an electromagnetic mechanical ultrasonic measurement method for detecting ultrasonic waves in a material having a conductive surface electromagnetically and non-contactly. That is, an ultrasonic transmitter having a conductive surface separate from the material having a conductive surface to be measured is placed on the material having a conductive surface to be measured, and a magnetic field is applied near the boundary between the two. On the other hand, when ultrasonic waves are generated in the ultrasonic transmitter having a conductive surface by a conventional method, an eddy current is generated on the surface of the ultrasonic transmitter having a conductive surface on the side of the material having a conductive surface due to the interaction between the mechanical displacement caused by the ultrasonic waves that reach the surface of the ultrasonic transmitter having a conductive surface on the side of the material having a conductive surface and the magnetic field that is applied in advance. Due to the influence of this eddy current, an eddy current is also generated on the surface of the material having a conductive surface to be measured according to the law of electromagnetic induction.
The interaction between the eddy current and the magnetic field causes a mechanical displacement in the material having a conductive surface, generating an ultrasonic wave. Regarding the detection means, for example, when an ultrasonic wave arrives at the surface of a material having a conductive surface to which a magnetic field is applied, a mechanical displacement occurs at the part where the ultrasonic wave arrives, so an eddy current is generated by interaction with the magnetic field.

Due to the influence of this eddy current, an eddy current is also generated on the surface of the ultrasonic transmitting medium having a conductive surface according to the law of electromagnetic induction.
The interaction of the eddy currents with the magnetic field produces mechanical displacement in an ultrasonic transmitter having a conductive surface, generating ultrasonic waves which can be easily detected by conventional ultrasonic detection means. The present invention will now be described in detail with reference to the following examples.

Fig. 1a is an embodiment of electromagnetically and non-contactly penetrating a longitudinal ultrasonic wave into a material having a conductive surface, and Fig. 1b is an embodiment of electromagnetically and non-contactly detecting a longitudinal ultrasonic wave in a material having a conductive surface. Fig. 2a is an embodiment of electromagnetically and non-contactly penetrating a shear ultrasonic wave into a material having a conductive surface, and Fig. 2b is an embodiment of electromagnetically and non-contactly detecting a shear ultrasonic wave in a material having a conductive surface. In Fig. 1a, a longitudinal ultrasonic wave is penetrated into an ultrasonic transmitter 1 having a conductive surface from above the ultrasonic transmitter 1 having a conductive surface by a conventional method using a conventional ultrasonic generator 2.

The ultrasonic longitudinal wave penetrates in the direction of the arrow indicated by 3, reaches the bottom of the ultrasonic transmitter 1 having a conductive surface, and causes mechanical displacement as indicated by the arrow 4. An electromagnet 6 is disposed near the bottom of the ultrasonic transmitter 1 having a conductive surface and the surface of the material 5 having a conductive surface to be measured.
A magnetic field indicated by an arrow 7 is applied in advance by the ultrasonic transducer 1. The mechanical displacement indicated by an arrow 4 and the magnetic field indicated by an arrow 7 interact with each other according to the right-hand rule of electromagnetic induction, and an induced current indicated by an arrow 8 is generated under the ultrasonic transducer 1 having a conductive surface. Influenced by the current 8, an induced current 9 is generated near the surface of the material having a conductive surface. The current 9 and the magnetic field 7 interact with each other according to the left-hand rule of electromagnetic induction, and a mechanical displacement indicated by an arrow 10 is generated. The mechanical displacement travels in the direction indicated by an arrow 11 as an ultrasonic wave. Figure 1b illustrates a method for detecting longitudinal ultrasonic waves using the device used in Figure 1a. A longitudinal ultrasonic wave traveling in the direction of an arrow 12 from inside a material 5 having a conductive surface reaches the vicinity of the surface of the conductive material and causes a mechanical displacement indicated by an arrow 13. This mechanical displacement interacts with the magnetic field indicated by an arrow 7, and generates a current indicated by an arrow 14 according to the right-hand rule of electromagnetic induction. Under the influence of this current, a current 15 is induced under the ultrasonic transmission body having a conductive surface. The current 15 and the magnetic field 7 interact with each other according to the left-hand rule of electromagnetic induction, causing a mechanical displacement as shown by the arrow 16. The mechanical displacement is a longitudinal ultrasonic wave as shown by the arrow 16.
7, the shear wave propagates in the direction of the halt and is easily detected by the conventional ultrasonic transducer 2. In FIG. 2a, a conventional ultrasonic transducer 19 transmits a shear wave ultrasonic wave into the ultrasonic transmitter 18 having a conductive surface from above the ultrasonic transmitter 18 having a conductive surface by a conventional method.

The penetrated ultrasonic transverse wave travels in the direction of the arrow indicated by 20, reaches the lower part of the ultrasonic transmitter 18 having a conductive surface, and causes mechanical displacement as indicated by arrow 21. A magnetic field as indicated by arrow 23 is applied in advance by the magnetic field generating coil 22 to the lower part of the ultrasonic transmitter 18 having a conductive surface and near the surface of the material 5 having a conductive surface, which is the measurement target. Note that since the magnetic field generating coil 22 is supported by the ultrasonic transmitter 18 having a conductive surface and is located away from the material 5 having a conductive surface, the magnetic field generating coil 22 loses its effectiveness for materials having particularly high-temperature conductive surfaces or materials having particularly rough conductive surfaces, which is a feature of the present invention (
The mechanical displacement indicated by arrow 21 and the mechanical displacement indicated by arrow 23
The magnetic field 23 interacts with the conductive surface of the ultrasonic transmitter 18 according to the right-hand rule of electromagnetic induction, and a current 24 is generated under the ultrasonic transmitter 18 having a conductive surface. In addition, an induced current 25 is generated near the surface of the material having a conductive surface under the influence of the current 24. The current 25 and the magnetic field 23 interact with each other according to the left-hand rule of electromagnetic induction, and a mechanical displacement is generated as indicated by the arrow 26. This mechanical displacement is indicated by the arrow 27.
FIG. 2b explains a method for detecting ultrasonic shear waves by the device used in FIG. 2a. The ultrasonic shear waves traveling in the direction of the arrow 28 from inside the material 5 having a conductive surface reach the vicinity of the surface of the material having a conductive surface and are detected in the direction of the arrow 28.
9. This mechanical displacement interacts with the magnetic field indicated by arrow 23, and the interaction occurs according to the right-hand rule of electromagnetic induction, generating a current indicated by 30. Influenced by this current, an induced current 31 is generated under the ultrasonic transmission body 18 having a conductive surface. The current 31 and the magnetic field 23 interact according to the left-hand rule of electromagnetic induction, generating a mechanical displacement indicated by arrow 32. This mechanical displacement flows as a shear wave ultrasonic wave, indicated by arrow 33.
The hail travels in the direction of the hail and is easily detected by the ultrasonic transducer 19 in a conventional manner.
As the ultrasonic transmitter having a conductive surface as shown in Fig. 2A and Fig. 2b, a cylindrical or rectangular parallelepiped non-structural (single member) aluminum or copper probe is suitable, but other metals with a structure, or even nonmetallic materials, can be used as long as they have a thin conductive surface with metal foil attached to the underside. The stronger the magnetic field, the higher the efficiency of ultrasonic generation and detection, but practically a magnetic field of about 10 kg will suffice. The shorter the distance between the ultrasonic transmitter and the object to be measured, the higher the efficiency, but a distance of 2 mm is recommended.
When copper is used as the ultrasonic transmitter, the temperature of the object to be measured is 10
As described above, it has been made clear that the present invention makes it possible to transmit and detect ultrasonic waves through the ultrasonic transmitter 1, 18 having a conductive surface in an electromagnetic and non-contact manner.

The method of generating and detecting ultrasonic waves in the present invention is shown in FIG.
The present invention is not limited to those shown in Fig. 2A and b, and the conventional ultrasonic transducer may be a disk type vibrating in the radial direction, an oblique type transducer, a pulse magnetic field or a permanent magnet may be used as the applied magnetic field, or ultrasonic generation and detection may be performed by separate devices, all of which are merely one embodiment of the present invention. As described above, the present invention can penetrate and detect ultrasonic waves into a material having a conductive surface without contact without using a coil or other structure, so it is not only effective for ultrasonic measurement of materials having a conductive surface in general, but also provides a particularly effective ultrasonic measurement means since protective measures such as coils are not required when measuring materials having a very high temperature conductive surface or materials having a very rough conductive surface.

[Brief description of the drawings]

1A, 1B and 2A, 2B are schematic cross-sectional views showing an embodiment of the present invention. In the drawings, 5 is a measurement object, 6 is an electromagnet, 22 is a coil, 1,
Reference numeral 18 denotes an ultrasonic transmitter, and reference numerals 2 and 19 denote ultrasonic transducers.

Claims (1)

[Claims] 1. An ultrasonic measurement method comprising the steps of: causing a magnetic field to exist in and near a measurement object having a conductive surface; generating an induced current on the surface of the ultrasonic transmitter by the interaction between the vibration of an ultrasonic transmitter having a conductive surface to which ultrasonic vibrations are applied from the outside and the magnetic field; further generating an induced current in the measurement object by electromagnetic induction; generating ultrasonic vibrations in the measurement object by the interaction between the induced current and the magnetic field. 2. An ultrasonic measurement method comprising the steps of causing a magnetic field to exist in and near a measurement object having a conductive surface, and disposing an ultrasonic vibration transmitter facing the measurement object; generating an induced current on the surface of the measurement object by the interaction between the ultrasonic vibration of the measurement object and the magnetic field; further generating an induced current on the surface of the ultrasonic vibration transmitter having a conductive surface by electromagnetic induction; generating ultrasonic vibrations in the ultrasonic vibration transmitter by the interaction between the induced current and the magnetic field; and detecting the ultrasonic vibrations. 3. An ultrasonic measuring device comprising an ultrasonic vibration transmitter having a conductive surface to which ultrasonic vibrations are applied from the outside, and a magnetic field generating device which is provided facing the object to be measured and which generates a magnetic field in and around the object to be measured having a conductive surface.