JPH0161188B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic measurement method that applies torsional stress to a polycrystalline ferrimagnetic material used as a communication device circuit element and measures changes in magnetic flux in a direction perpendicular to the excitation direction. It is.

When a polycrystalline ferrimagnetic material is used as a communication device circuit element, it is subjected to various external stresses depending on its structure and mounting method. As a result, the state of internal magnetization changes due to the reverse effect of magnetostriction, making the operation of the circuit element unstable.
Therefore, it is desirable that the magnetic material used as a communication device circuit element has a small magnetostriction, but to do so, it is necessary to at least measure the magnetostriction in advance to understand the characteristics of the magnetic material. becomes.

The present invention was invented in view of this situation, and provides a measurement method for applying torsional stress to a ferrimagnetic material for a communication device circuit and measuring changes in magnetic flux in a direction perpendicular to the excitation direction. Yes, especially
The present invention provides an evaluation test method for a magnetically stable ferrimagnetic material that exhibits little change in magnetic flux in the direction perpendicular to the excitation direction in response to torsional stress.

The above phenomenon has long been known as the reverse Wiedemann effect, in which alternating magnetization occurs along the circumference of a circular tube when a circular ferromagnetic material is twisted around its axis and an alternating magnetic field is applied in the axial direction. There is. This effect occurs because the direction of magnetization and magnetic domains are rearranged depending on the reiki strain constant, magnetic anisotropy constant, presence of vacancies, etc. in order to minimize internal energy due to stress. This is because

From the above-mentioned point of view, the method according to the present invention has the following features:
This is a simple and efficient method for measuring in order to obtain a polycrystalline ferrimagnetic material with a small reverse Wiedemann effect. In the magnetic measurement method of the present invention, a magnetic body of a material to be measured is formed into a rectangular column shape having a through hole in the center, an excitation coil is wound in the circumferential direction of the columnar magnetic body, and a magnetic flux detection coil is attached to the columnar magnetic body. The magnetic flux detection coil of the columnar magnetic body is wound in a direction perpendicular to the excitation coil through a through hole in the body, and the magnetic flux detection coil of the columnar magnetic body is further wound around a pair of U-shaped external magnetic yokes so as to straddle the excitation coil. one end of the columnar magnetic body through a non-magnetic jig while the excitation coil is energized to excite the columnar magnetic body in the axial direction. Torsional stress is applied to the columnar magnetic body by fixing it and rotating the other end through a non-magnetic jig, and by detecting the induced voltage generated in the magnetic flux detection coil at this time, the torsional stress is detected. This magnetic measurement method is characterized by measuring changes in magnetic flux in a direction orthogonal to the excitation direction.

Embodiments of the present invention will be described below based on the drawings.

FIG. 1a is a perspective view of a rectangular columnar ferrimagnetic material to be measured sample 1 having a through hole in the center. Samples of ferrimagnetic ceramic material in this shape can be easily obtained by conventional pressure molding and firing methods. In FIG. 1b, an excitation coil 2 and a magnetic flux detection coil 3 which passes through the center hole at right angles to the coil 2 and is wound around one or two sides of the columnar magnetic material are arranged on the columnar magnetic material sample 1, and further, FIG. 2 is a perspective view of a pair of external magnetic yokes 4, 4 disposed on two opposite sides of the coil 3, which are not wound, across the coil 2; By attaching the pair of external magnetic yokes 4, 4, the influence of the demagnetizing field of the sample is naturally reduced, and the accuracy of magnetic flux measurement can be improved with a smaller excitation current. Further, since the sample shape is a rectangular columnar shape, the contact portion of the external magnetic yoke 4 with the sample also becomes a flat surface, which facilitates the manufacture of the yoke 4 and reduces magnetic flux leakage at that portion.

FIG. 2 is a diagram showing an example of a non-magnetic jig 5 for holding both ends of the columnar magnetic material sample 1 in its mouth. In the figure, a is a front view thereof, b is a perspective view thereof, and c is another embodiment. In the figure, 6 is a slit for passing the magnetic flux detection coil 3 through, and 7 is a mounting hole for mounting the jig 5. Since the magnetic body to be measured is made into a rectangular columnar shape, the gripping jig 5 that applies twisting stress can be processed independently and easily as described above.

FIG. 3 is a sectional view of an apparatus for applying torsional stress to a columnar magnetic material measurement sample and measuring its magnetic flux density.

In the figure, 1, 2, 3, and 4 are the same signals as shown in FIG. Non-magnetic jigs 5, 5 that hold both ends of the columnar magnetic material measurement sample 1 in their mouths, and a cylinder 8 whose central axis is coaxial with the columnar magnetic material 1 and which are connected to one of the gripping jigs 5, to allow the cylinder 8 to rotate. bearing 9, a bearing support 10, an arm 11 attached to the cylinder 8 to apply torsional stress to the columnar magnetic body 1, and a fixing jig for fixing the other gripping jig 5 and the bearing support 10. It consists of 12. In the actual measurement, a load is applied to the arm 11, and the required torque amount can be varied at any time by changing the position of the arm to which the load is applied and the magnitude of the load.

Figure 4 shows that using this measurement method, three materials with different amounts of manganese (x in the composition Y ₃ Fes−xMnxO ₁₂ = 0, 0.09, 0.18) and whose coercive force, grain size, and porosity are almost the same (sample size: 6 mm square, hole diameter: 2 mmφ) when torsional stress is applied in the same direction. In the results of measuring the circumferential residual magnetic flux density, the horizontal axis shows the torque magnitude and the horizontal axis shows the residual magnetic flux density. Since the measuring device itself is sufficiently capable of measuring several Gauss, it can be seen that using the method of the present invention, it is possible to sufficiently distinguish even finer differences. It has been shown that even extremely small torques are possible. From this, it can be said that it is also possible to detect the amount of torque. The fact that the load torque can be small is also advantageous in this respect because damage to the sample can be avoided.

When measuring with the same sample, a coil is wound around the sample to detect the magnetic flux density generated in the same direction as the excitation coil 2 in Figure 1b, that is, in the same direction as the excitation direction of the sample, and changes in the residual magnetic flux density are measured. When measured,
In all cases, the magnitude of the change in residual magnetic flux density in the direction perpendicular to the excitation direction was less than 30%.

As is clear from the above description, the method according to the present invention can measure changes in magnetic flux in a direction perpendicular to the excitation direction with high precision by applying torsional stress to the ferrimagnetic material for communication device circuits. This invention is effective as an evaluation test method for ferrimagnetic materials that are magnetically stable due to slight changes in magnetic flux in the direction perpendicular to torsional stress, and is an extremely useful invention in practice.

[Brief explanation of drawings]

Fig. 1a is a perspective view of the sample to be measured, Fig. 1b is a perspective view of the sample to be measured with a yoke and a yoke attached to it to form a magnetic circuit, and Fig. 2 is a perspective view of the sample to be measured with a yoke and a yoke attached to it. FIG. 3 shows an example of a gripping jig, in which a is a front view, b is a perspective view, c is a front view of another embodiment, and FIG. FIG. 4 is a cross-sectional view of a device for measuring changes in magnetic flux in the orthogonal direction, and is a characteristic diagram of an actual measurement example. 1...Ferimagnetic material, 2...Excitation conductor, 3...
Detection coil for magnetic flux measurement, 4...Yoke, 5...Jig for holding sample ferrimagnetic material, 6...Slit drilled in the jig to pass the detection coil, 7...Jig mounting hole, 8... ...Cylinder, 9...Bearing,
10...Bearing support, 11...Arm, 1
2...Fixing jig. Note that the same or corresponding parts in the figures are given the same reference numerals.

Claims (1)

[Claims] 1. A magnetic body of the material to be measured is formed into a rectangular columnar shape having a through hole in the center, and an excitation coil is wound in the circumferential direction of the columnar magnetic body, and a magnetic flux detection coil is passed through the through hole of the columnar magnetic body to excite the excitation coil. winding in a direction perpendicular to the excitation coil, and furthermore, attaching a pair of U-shaped external magnetic yokes to two opposing sides of the columnar magnetic body on which the magnetic flux detection coil is not wound, so as to straddle the excitation coil. With the excitation coil being energized to excite the columnar magnetic body in the axial direction, one end of the columnar magnetic body is fixed via a non-magnetic jig, and the other end is non-magnetic. By applying torsional stress to the columnar magnetic body by rotating it through a magnetic jig and detecting the induced voltage generated in the magnetic flux detection coil at that time,
A magnetic measurement method characterized by measuring changes in magnetic flux in a direction orthogonal to the excitation direction due to torsional stress.