JPH0347443B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a device that generates a pulsed ultrasonic signal in a simple and efficient manner on a cylindrical or rod-shaped metal column.

(Prior art) Conventional electrical methods for propagating ultrasonic signals into a metal tube or rod include attaching an electromagnetic, magnetostrictive, or electrodynamic type ultrasonic transducer to the metal tube or rod. Alternatively, a method is used in which an insulated conducting wire is wound around the outside of a metal tube or rod to form a coil, and an electric current is instantaneously passed through the coil to insert an ultrasonic signal into the tube or rod. However, in the former method using an ultrasonic transducer, it is difficult to match the shape and dimensions of the ultrasonic transducer and the tube or rod, and in the latter method, the direction of the magnetic field generated by the coil is difficult to match. Since the direction of the material of the tube or rod is the same, there is little cross-linking of magnetic fields, making it impossible to efficiently insert ultrasonic signals and making it difficult to propagate large amplitude ultrasonic signals over long distances.

(Object of the Invention) The present invention was made in view of the above drawbacks, and by closely adhering a flat coil formed in a spiral shape along the outer circumferential surface of a cylindrical or rod-shaped metal column, a large-amplitude signal can be generated inside the column. It is designed to generate pulsed ultrasonic signals. The present invention will be explained in detail below using the drawings.

(Structure of the Invention) A flat coil formed in a spiral shape using a conductive wire is closely attached along the outer peripheral surface of a cylindrical or rod-shaped metal column, a means for instantaneously passing an electric current is connected to the coil, and a flat coil formed in a spiral shape is attached to the metal column. This is an ultrasonic signal generator that generates ultrasonic waves.

(Description of an Embodiment) FIG. 1 shows an embodiment of a spiral coil according to the present invention. As shown in the figure, a flat spiral coil 1 is formed using an insulated conducting wire. FIG. 2 shows a state in which the coil 1 is brought into close contact with a column. As shown in the figure, a coil 1 is closely attached along the outer peripheral surface of a cylindrical or rod-shaped metal column 2, and one end 1a of the coil 1 is connected to a connecting terminal 7, and the other end 1b is connected to a connecting terminal 8. Connect a switch and a capacitor in series between 7 and 8. On the other hand, a power source 5 is connected to the capacitor 4 via a rectifier 6.

Next, the generation of a pulsed ultrasonic signal will be explained. First, the capacitor 4 is charged by the power source 5 and the rectifier 6. When the switch 3 is closed, a discharge current momentarily flows from the charged capacitor 4 and a magnetic field is generated in the diametrical direction of the metal column 2 to which the coil 1 is closely attached. When the material of the metal column 2 is a ferromagnetic material such as iron, the outer peripheral portion of the metal column 2 is magnetized by the magnetic field, and an attractive force is generated between the metal column 2 and the magnetic force generated by the coil 1. The column 2 is deformed in the radial direction. Along with this deformation, the lengthwise direction of the metal column 2 is also deformed, and pulsed ultrasonic waves are generated within the metal column 2.

In addition, when the material of the metal column 2 is a non-magnetic material such as aluminum, an eddy current is generated in the outer circumferential portion of the column 2 due to the magnetic field generated by the coil 1, and a repulsive force is generated between the column and the coil 1. Similarly, pulsed ultrasonic waves are generated.

In the first embodiment, a flat spiral coil was arranged in close contact with the outer periphery of the columnar body, but in the second embodiment, a plurality of spiral coils were arranged in a band shape in close contact along the outer circumferential surface of the columnar body. explain. First, a circular or elliptical spiral coil as shown in FIG. 3a, or a flat spiral coil wound in a square or rectangular shape as shown in FIG. 3b is formed. FIG. 4 shows a case where a circular spiral coil 9 is used, and a large number of coils 9 are arranged in a band shape along the outer peripheral surface of the metal column 2. As shown in FIG. Each coil 9 is wound in the same direction and is closely attached to the outer peripheral surface of the metal column 2. To connect each coil 9, both ends of the coil 9 may be connected in series or in parallel (FIG. 4 shows a case of series connection) and connected to the terminals 7 and 8 for connection to the sound source circuit. By configuring as described above, effects similar to those of the first embodiment described in FIG. 2 can be obtained.

(Effects of the Invention) According to the device of the present invention, it is possible to generate an ultrasonic signal directly into the metal column without using an ultrasonic transducer. Ultrasonic signals can be efficiently generated in the metal column without any matching loss due to differences in impedance. Further, in this method, since the magnetic field intersects the metal column at right angles, it is possible to efficiently obtain a high-output pulsed ultrasonic signal. Furthermore, since the flat coil surface can be brought into close contact with the outer circumferential surface of the target object, the distance between the coil and the target object can be kept narrow over a wide area, improving conversion efficiency and making it possible to obtain high-output ultrasonic signals. . Therefore, it is effective for measuring the length of long metal columns.

[Brief explanation of drawings]

Figure 1 shows a spiral coil according to the present invention, Figure 2 shows a first embodiment of an ultrasonic signal generator, Figure 3a shows a circular spiral coil, Figure 3b shows a rectangular spiral coil, and Figure 4 shows an ultrasonic wave generator. This is a second embodiment of the signal generator. 1, 9, 10...Vortex coil, 2...Metal column, 3...Switch, 4...Capacitor, 5...
Power supply, 6... Rectifier, 7, 8... Connection terminal.

Claims (1)

[Scope of Claims] 1. A flat coil formed in a spiral shape using a conducting wire is closely attached along the outer circumferential surface of a cylindrical or rod-shaped columnar body, a means for instantaneously passing an electric current is connected to the coil, and a superfluous coil is attached to the columnar body. An ultrasonic signal generator characterized by generating sound waves. 2. The ultrasonic signal generator according to claim 1, wherein the flat spiral coil is formed into a circle, an ellipse, a square, or a rectangle. 3. Claim 1, characterized in that a plurality of coils formed in a flat spiral shape are arranged in the same direction along the outer peripheral surface of the column, and each coil is connected in series or in parallel. The ultrasonic signal generator described above.