JPS6175259A - Electromagnetic ultrasonic transducer - Google Patents

Abstract

PURPOSE:To improve the operability, by forming a high frequency current path in a ladder to enable the implementation of an angle beam flaw detection involving a scanning in a completely non-contact manner simply by selecting the frequency of current flowing through the high frequency current path. CONSTITUTION:A high frequency current path 20 is built up in a ladder as a whole with a pair of main conductor sections 21a and 21b extending parallel and branch conductor sections 22 for connecting both the main conductors at the pitch P equal to the pitch P of arranging permanent magnets 11a-11d. It also is fastened on the surface of an electric insulator 2 in such a manner that the branch conductor sections 22 face respectively yokes 11a-12d. Then, as a high frequency current flows through the high frequency current path 20, a thigh frequency induced eddy current 25 runs through the surface of material B to be inspected to generate an ultrasonic wave 27. In addition, the ultrasonic wave 27 can be controlled in the direction of propagation by varying the frequency of the high frequency current to be fed to enable the implementation of an angle beam flaw detection of the material B being inspected involving a scanning and in a non-contact manner thereby improving the ease of use.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electromagnetic ultrasonic transducer, and in particular:
This invention relates to an electromagnetic ultrasonic transducer that has greatly improved ease of use.

[Technical background of the invention and its problems]

An ultrasonic transducer is required to perform an ultrasonic flaw detection test. Various types of ultrasonic transducers have been proposed in the past. An electromagnetic ultrasonic transducer is known as one of these ultrasonic transducers. Unlike those that use magnetostrictive elements or electrostrictive elements, this electromagnetic ultrasonic transducer uses an 〇-lenska to generate ultrasonic waves in the material to be inspected, and is in a non-contact state with the material to be inspected. It has the feature that it can be set to Therefore, even if the surface of the material to be inspected has irregularities, the test can be carried out without any special measures.

Incidentally, such an electric sonic transducer is usually constructed as shown by A in FIG. 5. In other words, this electromagnetic ultrasonic transducer A is mainly composed of a magnetic block 1 and a high frequency current path 3 disposed on one side of the magnetic block 1 via a thin electrical insulating material 2. There is.

The magnetic block 1 includes a plurality of permanent magnets 11a, 11b,
11G, . . . and a plurality of yokes 12a, 12b, 12G, . Each permanent magnet 11a, 11b, 11C1
. . . are each formed into the same flat plate shape, and are each magnetized in the thickness direction. In addition, each yoke 12a, 12b112c,...
They are formed in the same shape, which is the same as the surface shape of each of the above-mentioned permanent magnets. The permanent magnets and yokes thus formed are laminated and integrated in such a way that the yokes are interposed between each permanent magnet, and the magnetization directions of adjacent permanent magnets with the yoke in between are different. A magnetic block 1 is configured.

On the other hand, the high frequency 1i21i path 3, as shown in the sixth factor,
It is composed of a zigzag-shaped conductor piece 13 extending in the stacking direction of the permanent magnets while being bent at the arrangement pitch of the permanent magnets in a direction perpendicular to the stacking direction of the permanent magnets constituting the magnetic block 1. As shown in FIG.
2b, 12c, . . . are fixed to the surface of the electrical insulating material 2 so as to face the end faces thereof.

When performing a flaw detection test on the material B to be inspected using the electromagnetic ultrasonic transducer A configured as described above, as shown in FIG. The high-frequency current path 3 is set so as to face the surface, with a predetermined gap C between the surface of the material to be inspected B and the high-frequency current path 3, and in this state, both ends of the high-frequency current path 3 are connected to a high-frequency power source (not shown) and a signal receiving device (not shown). Connected and ready for use.

Here, the operation of this electromagnetic ultrasonic transducer A will be briefly explained as follows. When this electromagnetic ultrasonic transducer A is set facing the surface of the material to be inspected B, each permanent magnet 11a, 11b, 11C1...
...The lines of magnetic force coming out from each yoke 12a112t), 12G, ... as shown by the broken line arrows in Fig. 7.
and inspected material B in series. Therefore, the bias magnetic field 14 perpendicular to the surface of the inspected material B is applied thereto. When a high-frequency current is passed through the high-frequency current path 3, the portion 13a of the conductor piece 13 constituting the high-frequency current path 3 is exposed to the numeral 15 in FIG.
As shown by , currents flow in opposite directions in adjacent portions 13a. This current causes a high frequency induced eddy current in the direction shown by 16 in FIG. 7 to flow on the surface of the material to be inspected B. Due to the interaction between this induced eddy current and the bias magnetic field 14, a Lorentz force 17 with the same phase is generated in the inspected material B in a direction parallel to the surface of the inspected material B, and a Lorentz force 17 is generated in a direction perpendicular to this Lorentz force 17. A transverse ultrasound wave 18 is generated. Ultrasonic waves are generated using this principle. Note that the portion 13a of the conductor piece 13 constituting the high frequency current path 3 is made of permanent magnets 11a, 11b, IC1...
By shifting it to a position opposite to the side surface of the object B, it is possible to generate a Lorentz force in a direction perpendicular to the surface of the material to be inspected B, and thereby it is also possible to generate longitudinal ultrasonic waves.

However, the conventional electromagnetic ultrasonic transducer A configured as described above can only generate ultrasonic waves perpendicular to the surface of the inspected material B. With the surface of material B! Sensitivity to direct defect X is very poor. Therefore, in order to deal with such defects, it is necessary to apply an oblique flaw detection method in which an acoustic member is interposed in the middle. For this reason, there was a problem in that, in principle, it was not possible to make full use of the features that non-contact probes were capable of, and on the contrary, it was difficult to use.

[Purpose of the invention]

The present invention was made in view of these circumstances, and its purpose is to enable completely non-contact use while maintaining good sensitivity, thereby greatly improving ease of use. An object of the present invention is to provide an electromagnetic ultrasonic transducer that can

[Summary of the invention]

The electromagnetic ultrasonic transducer according to the present invention is characterized in that the high frequency current path is formed in a ladder shape.

Furthermore, the electromagnetic ultrasonic transducer according to the present invention is characterized in that a ladder-like high-frequency current path and a zigzag-like high-frequency current path are installed side by side and insulated from each other.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an electromagnetic ultrasonic transducer A1 according to an embodiment of the present invention, partially taken out and cut.
The same parts as the conventional one shown in FIG. 5 are indicated by the same reference numerals. Therefore, the explanation of the overlapping parts will be omitted.

The electromagnetic ultrasonic transducer A1 according to this embodiment differs from the conventional one in the configuration of the high frequency current path 20.

In other words, the high frequency current path 20 is as shown in FIG.
For example, a thin conductive plate is punched to form a ladder-like structure as a whole. Specifically, the permanent magnet 11
a, 11t), 11G, . . . a pair of main conductor portions 21a and 21b extending parallel to each other in the fi1 direction;
The permanent magnet 11 is connected between these main electric conductor parts 21a and 21b.
It is composed of a plurality of branch conductor parts 22 connected at a pitch equal to the arrangement pitch P of a, 11b, 11C1, . . . The high frequency current path 20 configured as described above is arranged such that the branch conductor portion 22 faces the end surface of each yoke 12a, 12b, 12G, . . . with the electrical insulating material 2 in between. It is fixed to the surface of the electrical insulating material 2.

Electromagnetic ultrasonic transducer A! configured in this way!
When performing the Fukagawa test on material B to be inspected using
As shown in the figure, the side on which the high-frequency current path 20 is located faces the surface of the material to be inspected B, and the surface of the material to be inspected B and the high-frequency current path 20 are set with a predetermined gap C,
In this state, the main conductor portions 21a, 211) constituting the high frequency current path 20 are connected to the output end of a variable high frequency power source (not shown) and connected to a signal receiving device (not shown) for use.

With such a configuration, by simply selecting the frequency of the current flowing through the high-frequency current path 20, it is possible to perform an oblique flaw detection method that involves scanning in a completely non-contact manner.

That is, when this electromagnetic ultrasonic transducer Al is set facing the surface of the material to be inspected B, each permanent magnet 1
1a, 11b, 11C1..., the lines of magnetic force from each yoke 12a, 11C1, as shown by the broken line arrows in FIG.
2b, 12C1... and the material to be inspected B in series. Therefore, the bias magnetic field 23 perpendicular to the surface of the inspected material B is applied thereto. Therefore, when a high frequency current is passed through the high frequency current path 20, each of the conductor portions 2 constituting the high frequency current path 2o
As shown by 24 in FIG. 3, currents flow in the same direction. Due to this current, the surface of the material to be inspected B has a third
A high frequency induced eddy current flows in the direction indicated by 25 in the figure.

The interaction between this induced eddy current and the bias magnetic field 23 generates Lorentz forces 26a and 26b in the material B to be inspected. These Lorentz forces 26a and 26b are parallel to the surface of the material to be inspected B and have opposite phases to each other. As a result, the ultrasonic wave 27 generated in the material B to be inspected is a transverse wave and has a mode that propagates obliquely to the surface of the material B to be inspected.

In this case, if θ is the angle between the line 28 drawn perpendicularly to the surface of the inspected material B and the propagation direction of the ultrasonic wave 27, θ is given by the following equation.

θ=sin'(Vs/Pf) ・(1) However, (
In equation 1), Vs is the transverse wave velocity (m/sec) determined by the constituent material of the inspected material B, and P is the branch conductor portion 2.
2 mutual spacing (m), f is the frequency (H2) of the current supplied to the high frequency current path 20.

As can be seen from equation (1), the propagation direction of the ultrasonic waves 27 can be freely controlled by changing the frequency of the supplied high-frequency current, resulting in a scanning transducer. .

Therefore, the electromagnetic ultrasonic transducer Ar according to this embodiment can realize an oblique flaw detection method that is completely non-contact with the material B to be inspected and that involves scanning. Therefore, the ease of use is greatly improved compared to conventional ones, and the time required for inspection can be shortened. - For example, when used in the inspection of atomic couplants, it not only reduces the radiation exposure of inspectors, but also allows inspection to be carried out in a completely non-contact manner, thus contributing to the realization of inspections using robots.

FIG. 4 is a partially cut-away view of an electromagnetic ultrasonic transducer A2 according to another embodiment of the present invention.

In this figure, the same parts as in FIG. 1 are designated by the same reference numerals. Therefore, the explanation of the overlapping parts will be omitted.

This embodiment differs from the embodiment shown in FIG. 1 in that, in addition to the high-frequency current path 20, a unique high-frequency current path 40 is provided.

That is, a thin electrical insulating material 3 is placed on the outer surface of the high frequency current path 20.
0 is fixed, and a permanent magnet 11 is attached to the outer surface of this electrical insulating material 3o.
a, 11b, 11C1, . . . zigzags similar to those shown in FIG. The high frequency current path 40 of the configuration is fixed.

The high-frequency current path 40 is fixed in such a manner that a portion 40a perpendicular to the stacking direction of the permanent magnets overlaps the branch conductor portion 22 of the high-frequency current path 20 with the electrical insulating material 30 in between. ing.

With such a configuration, not only can the same effects as the embodiment shown in FIG. It is possible to generate ultrasonic waves perpendicular to the object. Therefore, since one transducer can be used for both oblique and vertical transducers, ease of use can be further improved.

〔Effect of the invention〕

As described in detail above, according to the present invention, it is possible to provide an electromagnetic ultrasonic transducer that is easy to use and can significantly shorten inspection time.

Further, according to the present invention, it is possible to provide an electromagnetic ultrasonic transducer that can further expand the degree of freedom of use.

[Brief explanation of the drawing]

FIG. 1 is a side view partially taken out and cut away to show an electromagnetic ultrasonic transducer according to an embodiment of the present invention;
The figure is a plan view showing only the high-frequency current path incorporated in the transducer, FIG. 3 is a diagram for explaining the principle of ultrasonic generation of the transducer, and FIG. 4 is a diagram showing another embodiment of the present invention. A side view showing an electromagnetic ultrasonic transducer partially taken out and cut away. The fifth cause is the conventional electric F! 1 is a side view partially taken out and shown by cutting the ultrasonic transducer; FIG. 6 is a plan view taken out and showing only the high-frequency current path built into the transducer;
FIG. 7 is a diagram for explaining the principle of ultrasonic generation of the same transducer, and FIG. 8 is a diagram for explaining problems with the same transducer I. A+, A2... Electromagnetic ultrasonic transducer, 1.
...Magnetic block, 2.30...Electric insulation material, 11a
, 11b, 11c, ---permanent 18 stones, 12a,
12b, 12C1... Yoke, 20.40.
...High frequency current path. Applicant's representative Patent attorney Takehiko Suzue (Figure 1, Figure 2, 21t) Figure 3, Figure 4, Figure 5, Figure 6, Day 7, Figure 8

Claims (4)

[Claims] (1) A magnetic block formed by stacking a plurality of permanent magnets of the same shape, with a yoke interposed between each other, and adjacent permanent magnets having different magnetization directions across the yoke; A pair of main current body portions extending parallel to each other in the stacking direction of the permanent magnets are disposed on one side of the magnetic block via an electrical insulating layer, and a pitch between the main current body portions is defined as the arrangement pitch of the permanent magnets. An electromagnetic ultrasonic transducer comprising a ladder-like high-frequency current path made up of a plurality of branch conductor parts connected at equal pitches. (2) The electromagnetic superconductor according to claim 1, wherein the branch conductor portion of the high-frequency current path is provided at a position facing each of the yokes with the electrical insulating layer in between. Sonic transducer. (3) a magnetic block formed by stacking a plurality of permanent magnets of the same shape, with a yoke interposed between each other, and adjacent permanent magnets having different magnetization directions across the yoke; A pair of main current body portions extending parallel to each other in the stacking direction of the permanent magnets are disposed on one side of the magnetic block via an electrical insulating layer, and a pitch between the main current body portions is defined as the arrangement pitch of the permanent magnets. A ladder-shaped first high-frequency current path consisting of a plurality of branch conductor portions connected at equal pitches and the first high-frequency current path are arranged on the one side of the magnetic block so as to be electrically insulated from each other, and the first high-frequency current path is electrically insulated from the permanent A second high-frequency current path formed of a zigzag-shaped conductor piece extending in the lamination direction of the permanent magnets while being bent in a direction perpendicular to the lamination direction of the magnets. Sonic transducer. (4) The branch conductor portion of the first high-frequency current path and the portion of the second high-frequency current path perpendicular to the stacking direction of the permanent magnets are arranged at positions facing the yoke, respectively. An electromagnetic ultrasonic transducer according to claim 3, characterized in that: