JP2803917B2 - Magnetic anisotropy detection method for steel sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting magnetic anisotropy of a steel sheet, which detects magnetic anisotropy which is one of the factors that determine the properties of the steel sheet.

[0002]

2. Description of the Related Art A magnetic anisotropy detector for detecting the magnetic anisotropy of a steel sheet is already known in Japanese Patent Application Laid-Open No. 62-204174 and others. This conventional detector is provided with two U-shaped cores having coils wound at both ends in an orthogonal shape, and four U-shaped cores at both ends of each core.
The magnetic poles are square.

[0003] Of the two cores, two coils of one core are used for excitation, and two coils of the other core are used for detection. And
The difference between the electromotive forces induced in the two coils is measured by applying a high-frequency current to the excitation coil and measuring the difference between the electromotive forces induced in the detection coils. Now, when two cores of the detector are placed on a sample having magnetic anisotropy, an angle between the direction of the excitation core and the easy magnetization direction of the sample is defined as θ. θ
When = 0, the magnetic flux emitted from the excitation coil passes through the two detection coils under the same conditions, so that the difference between the electromotive forces induced by the two becomes zero. However, when θ ≠ 0, the magnetic flux emitted from the exciting coil tends to flow in the easy magnetization direction of the material, and
There is a difference between the electromotive forces induced in the detection coils. Therefore, when this detector is rotated once on the sample, the difference between the electromotive forces of the two detection coils changes in a sinusoidal manner, and the magnetic anisotropy of the sample can be known from the sinusoidal signal.

[0004]

In the prior art, in order to know the anisotropy of the steel sheet, it is necessary to rotate the steel sheet and the detector relatively, and to measure the anisotropy of the material at high speed. It is difficult. In particular, since it is difficult to rotate a large steel plate, it is necessary to rotate the detector in that case. On the other hand, if the detector is rotated, a slip ring or the like is required, and there is a disadvantage that the entire detector becomes large.

The present invention has been made in view of the above circumstances, and it is intended that the same effect as when the sample and the detector are relatively rotated can be obtained even when the detector is stationary with respect to the sample. Aim.

[0006]

According to the present invention, there are provided two U-shaped cores 2, having excitation coils 4, 5, 6, 7 wound at both ends and detection coils 8, 9 wound at an intermediate portion. 3 are orthogonally connected, each excitation coil 4,5,6,7 is harmonically connected, and each detection coil 8,9 is differentially connected. A high-frequency voltage determined in relation to the thickness of the steel sheet is applied from the phase constant voltage power supply to generate a rotating magnetic field in a plane formed by the tip surfaces of the cores 2 and 3 and connected to the detection coils 8 and 9. The lock-in amplifier for voltage detection sets the phase to be locked from 0 degree to 360
The output corresponding to the difference in magnetic resistance in each core direction is measured for each magnetization phase of the rotating magnetic field.

[0007]

[Function] A rotating magnetic field that rotates at the frequency used for the excitation is generated in the vicinity of the magnetic poles of the four excitation coils 4, 5, 6, and 7 wound on both ends of the two cores 2, 3. I do. Each core 2,3
The difference between the electromotive forces induced in the detecting coils 8 and 9 wound around the intermediate portion of each of them and differentially connected thereto is measured.

The output of the lock-in amplifier is changed by using one phase of a three-phase constant-voltage power supply used for excitation as the standard voltage of the lock-in amplifier and changing the phase to be locked from 0 degrees to 360 degrees. And a sine wave equivalent to a signal generated when the conventional detector and sample are relatively rotated once. Therefore, the zero cross point of the sine wave signal is obtained, and the easy magnetization direction of the steel sheet is obtained from the magnetization phase direction of the rotating magnetic field at that time.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. FIG. In FIG. 1, two U-shaped cores 2 and 3 made of a ferromagnetic material include:
Excitation coils 4,5,6,7 at both ends, detection coil at middle
8 and 9 are wound respectively, and the two cores 2 and 3 are arranged orthogonally. The cores 2 and 3 were annealed with 45% permalloy rods, and the excitation coils 4, 5, 6, and 7 were 8%.
00 turns (0.2 mm), detection coils 8, 9 are 1,200 turns (0.05 m
m).

The exciting coils 4, 5, 6, 7 of each of the cores 2, 3 are connected in a pulsating manner as shown in FIG. 2, and are supplied from a three-phase constant voltage power supply having a phase difference of 120 degrees to the thickness of the steel sheet. A high-frequency voltage of 10 V of three phases of 200 Hz specified in relation thereto is applied.
Therefore, at this time, the magnetic poles 10, 11 of the respective exciting coils 4, 5, 6, 7
, 12, and 13, a rotating magnetic field is generated in the direction indicated by the arrow B in the plane formed by the end faces of the cores 2 and 3, as shown in FIG.

At this time, the detection coils 8 and 9 are connected differentially and connected to a lock-in amplifier for voltage detection, and one phase of a three-phase constant voltage power supply is set as a standard voltage by the lock-in amplifier. When the phase to be locked is changed from 0 ° to 360 ° by automatically running at a period of 10 seconds, the outputs of the detection coils 8 and 9 become sinusoidal signals as shown in FIG. Therefore, the peak position and the valley position in the sinusoidal signal shown in FIG. 5 are obtained, and the magnetic anisotropy of the steel sheet can be detected from the direction of the magnetization phase of the rotating magnetic field at that time. That is, for each magnetization phase of the rotating magnetic field, the magnetic anisotropy of the sample is detected by measuring the output corresponding to the difference in the magnetic resistance in each core direction.

[0012]

According to the present invention, the exciting coils 4,
5, 6, 7 are provided with two U-shaped cores 2, 3 having detection coils 8, 9 wound therearound in the middle part in an orthogonal shape, and the respective excitation coils 4, 5
Using a magnetic anisotropy detector 1 in which the detection coils 8 and 9 are differentially connected by summing connections of 6, 7 and The high-frequency voltage determined in the above procedure is applied to generate a rotating magnetic field in the plane created by the end faces of the cores 2 and 3, and the three-phase voltage is detected by the lock-in amplifiers for voltage detection connected to the detection coils 8 and 9. With one phase of the voltage power supply as the standard voltage, the phase to be locked is changed from 0 degrees to 360 degrees, and the output corresponding to the difference in the magnetic resistance in each core direction is measured for each magnetization phase of the rotating magnetic field. With the detector 1 still, a signal equivalent to the case where the detector and the sample are rotated once relative to each other as before can be obtained.
Therefore, the magnetic anisotropy of the steel sheet can be easily and easily detected, and the whole can be reduced in size.

[Brief description of the drawings]

FIG. 1 is a perspective view of a detector.

FIG. 2 is a connection diagram of an exciting coil.

FIG. 3 is a timing chart of an exciting current.

FIG. 4 is an explanatory diagram of a rotating magnetic field.

FIG. 5 is an explanatory diagram of a lock-in amplifier output.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Magnetic anisotropy detector 2 Core 3 Core 4 Exciting coil 5 Exciting coil 6 Exciting coil 7 Exciting coil 8 Detecting coil 9 Detecting coil

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Norio Suzuki 4-25 Hanayamadai, Kita-ku, Kobe-shi, Hyogo (56) References JP-A-52-88392 (JP, A) JP-A-53-116891 (JP) JP-A-55-46143 (JP, A) JP-A-56-150348 (JP, A) JP-A-62-204174 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB G01R 33/12 G01N 27/72

Claims (1)

(57) [Claims] 1. Excitation coils (4) (5), (6) (7) at both ends,
Equipped with two U-shaped cores (2) and (3) wound around detection coils (8) and (9) in the middle, the excitation coils (4) (5) and (6)
Using a magnetic anisotropy detector (1) with (7) harmonically connected and differentially connected detection coils (8) and (9), from a three-phase constant-voltage power supply with a phase difference of 120 degrees, A high-frequency voltage determined in relation to the thickness is applied to generate a rotating magnetic field in the plane created by the tip surface of each core (2) (3), and the voltage detection connected to the detection coils (8) and (9) Lock-in amplifier for the three-phase constant-voltage power supply
With the phase as the standard voltage, the phase to be locked is changed from 0 degrees to 360 degrees, and the output corresponding to the difference in the magnetic resistance in each core direction is measured for each magnetization phase of the rotating magnetic field. Magnetic anisotropy detection method.