JP5631344B2 - Magnetostriction measuring method and magnetostriction measuring apparatus - Google Patents

Description

  The present invention relates to a magnetostriction measuring method and a magnetostriction measuring apparatus for measuring magnetostriction of a magnetic material.

  When a magnetic material is used in a magnetic field, it undergoes magnetostriction that expands and contracts under the influence of the magnetic field. This magnetostriction causes vibration and noise in an electromagnetic device using a magnetic material in a magnetic field. Therefore, the magnetostriction of the magnetic material is an important factor in selecting the material when designing an electromagnetic device or the like.

  Various methods for measuring the magnetostriction of this magnetic material have been conceived in the past, but as a method for measuring fine strain well, the amount of displacement of the magnetic material placed in a magnetic field can be measured with a laser. A magnetostriction measuring method for measuring magnetostriction of a magnetic material by measuring with a Doppler vibrometer is known.

  Conventional magnetostriction measurement methods are roughly classified into two types.

  In the first magnetostriction measurement method, a magnetic material to be a sample is placed in a coil for forming a magnetic field, one end of the sample is fixed and the other end is a free end, and a reflector is placed on the free end side of the sample. Is attached, and the magnetostriction of the sample is measured by irradiating laser light from the laser Doppler vibrometer toward the reflector (see Non-Patent Document 1).

  In the second magnetostriction measurement method, a magnetic material to be a sample is arranged in a coil for forming a magnetic field, two reflectors are attached in a uniform magnetic field region on the sample, and directed to each reflector. Then, the magnetostriction of the sample is measured by irradiating the laser beam from the laser Doppler vibrometer (see Non-Patent Document 2).

IEC / TR 62581 TECHNICICAL REPORT "Comparison of optical measurement method and strain gauge method in magnetostriction measurement" MAG-98-65

  However, in the first magnetostriction measurement method, since the nonuniform magnetic field regions are formed at both ends of the coil, the magnetostriction due to the uniform magnetic field cannot be accurately measured, and the magnetostriction measurement accuracy is high. It was low.

  Further, in the second magnetostriction measurement method, measurement must be performed by irradiating each of the two reflectors with laser light, and the displacement amount between the two points cannot be measured simultaneously. The measurement accuracy of magnetostriction was low.

Therefore, in the present invention according to claim 1, the amount of displacement between the first and second target points in the uniform magnetic field region on the sample placed in the magnetic field is measured by the optical measuring means. In a magnetostriction measurement method for measuring magnetostriction of a sample, a first target point and a second target point are provided in a uniform magnetic field region in which a magnetic field formed on the center side of a magnetic field generated by a coil is uniform, and optical The light emitted from the target measuring means is reflected at the first target point toward the second target point, reflected at the second target point toward the first target point, and then at the first target point to the optical measuring means. And decided to reflect.

  Further, in the present invention according to claim 2, in the present invention according to claim 1, light is emitted from the optical measuring means in an oblique direction with respect to the extending direction of the sample, avoiding the yoke connected to the sample. I decided to radiate.

In the present invention according to claim 3, the amount of displacement between the first and second target points in the uniform magnetic field region on the sample placed in the magnetic field is measured by the optical measuring means. In a magnetostriction measuring apparatus for measuring a magnetostriction of a sample, a first target point and a second target point are provided in a uniform magnetic field region in which a magnetic field formed on the center side of a magnetic field generated by a coil is uniform . A first reflector is provided at one reference point, a second reflector is provided at the second reference point, and light emitted from the optical measuring means is reflected toward the second reflector by the first reflector, The first reflector and the second reflector are arranged so as to be reflected toward the first reflector by the second reflector and reflected to the optical measuring means by the first reflector.

  Further, in the present invention according to claim 4, in the present invention according to claim 3, the light emitted from the optical measuring means is directed to the extending direction of the sample while avoiding the yoke connected to the sample. The optical measuring means is arranged so as to enter the first reflector obliquely.

  And in this invention, there exists an effect described below.

  That is, in the present invention, the magnetostriction of the sample is measured by measuring the amount of displacement between the first and second target points in the uniform magnetic field region on the sample placed in the magnetic field by the optical measuring means. In the magnetostriction measurement method (magnetostriction measurement apparatus) to be measured, the light emitted from the optical measuring means is reflected toward the second target point at the first target point, and then to the first target point at the second target point. Because it reflects to the optical measuring means at the first target point, the displacement between two points in the uniform magnetic field region can be measured at the same time, and the magnetostriction of the sample is accurate. It can be measured well.

  In particular, when it is decided to radiate light from the optical measuring means obliquely with respect to the extending direction of the sample while avoiding the yoke connected to the sample, even if the multiple yokes are connected to the front and back of the sample, The magnetostriction can be measured, and the magnetostriction of the sample can be measured with higher accuracy.

1 is a side sectional view showing a magnetostriction measuring apparatus according to the present invention. FIG. Explanatory drawing which shows the magnetostriction measuring method which concerns on this invention. The plane sectional view (a) and side sectional view (b) which show the magnetostriction measuring device concerning the present invention.

  Hereinafter, specific configurations of a magnetostriction measuring method and a magnetostriction measuring apparatus according to the present invention will be described with reference to the drawings.

  As shown in FIGS. 1 and 2, the magnetostriction measuring apparatus 1 has a hollow coil holder 3 attached to a casing 2.

  A coil 4 is wound around the outer periphery of the coil holder 3. A circuit for generating a predetermined magnetic field is connected to the coil 4.

  A sample holder 6 holding a sample 5 to be measured is placed in the hollow portion of the coil holder 3.

  The sample 5 is made of a rectangular plate-like magnetic material, and is inserted into the hollow portion of the sample holder 6 so as to be stretchable along the extending direction of the coil 4.

  The sample holder 6 has rectangular penetrating openings 7 and 8 formed on the upper left side and the upper right side. Then, the first reflector 9 and the second reflector 10 are attached to the sample 5 using the openings 7 and 8 of the sample holder 6. The sample holder 6 may further be provided with an opening for attaching a strain gauge or the like.

  In the magnetostriction measuring apparatus 1, an optical measuring means 11 such as a laser Doppler vibrometer that can optically measure the amount of displacement is attached to the casing 2 so that the direction of light irradiation can be adjusted. This optical measuring means 11 irradiates light (laser light) and receives reflected light (laser light) and measures the amount of displacement. In the laser Doppler vibrometer, the irradiation light and reflected light are measured. The displacement is measured from the wavelength variation due to the Doppler effect.

  Further, the magnetostriction measuring apparatus 1 is configured such that a multiple yoke 14 composed of a pair of front and back yokes 12 and 13 can be connected between the free ends of the sample 5. By connecting the yokes 12 and 13 to the sample 5, the distribution of the magnetic field applied to the sample 5 and the distribution of the magnetic flux inside the sample 5 can be made uniform.

  Next, a method (magnetostriction measurement method) for measuring the magnetostriction of the sample 5 using the magnetostriction measurement apparatus 1 will be described (see FIG. 3).

  In the magnetostriction measuring method, the magnetostriction generated in the sample 5 by the magnetic field generated by the coil 4 is measured from the amount of displacement between two points on the surface of the sample 5 measured by the optical measuring means 11.

Here, two points on the surface of the sample 5 are defined as a first reference point 15 and a second reference point 16, respectively, and a horizontal distance between the first reference point 15 and the second reference point 16 is L ₀ . The first reference point 15 and the second reference point 16 are provided in a uniform magnetic field region where the magnetic field formed on the center side of the magnetic field generated by the coil 4 is uniform.

  The first and second reflectors 15 and 16 are provided with a first reflector 9 and a second reflector 10, respectively, with the reflecting surfaces facing inward.

  The optical measuring means 11 is arranged so as to irradiate the first reflector 9 with light inclined obliquely by θ / 2 with respect to the extending direction of the sample 5. The first reflector 9 has a reflecting surface arranged perpendicular to the extending direction of the sample 5, and receives light incident from the optical measuring means 11 at an incident angle of θ / 2 with respect to the extending direction of the sample 5. The light is reflected toward the second reflector 10 at a reflection angle of θ / 2. The second reflector 10 is arranged such that the reflection surface is inclined by θ / 2 with respect to the extending direction of the sample 5 so that all the light reflected by the first reflector 9 is reflected toward the first reflector 9. I have to.

  Thereby, the light radiated from the optical measuring means 11 is reflected toward the second reflector 10 by the reflecting surface of the first reflector 9, and then the first reflector is reflected by the reflecting surface of the second reflector 10. 9 and then reflected to the optical measuring means 11 on the reflecting surface of the first reflector 9.

  When the magnetostriction of the sample 5 is measured, the first reflector 9 and the second reflector 10 are placed on the first and second target points 15 and 16 on the surface of the sample 5 using a jig in advance. Then, the measurement is performed after finely adjusting the light irradiation direction of the optical measuring means 11.

The displacement amount between the first gauge point 15 and the second gauge point 16 measured by the optical measuring means 11 is ΔS, and the displacement amount of the first gauge point 15 in the horizontal direction (the extending direction of the sample 5) is δ. _1, and the displacement amount in the horizontal direction of the second reference points 16 (extending direction of the sample 5) and [delta] _2, a direction inclined by theta / 2 relative to the extending direction of the light beam direction (sample 5 of the second gauge 16 ) ₃ )
ΔS = 2 · δ ₁ / cos (θ / 2) + δ ₂ · cos (θ / 2) −δ ₃
δ ₃ = 2 ・ δ ₁・ tan (θ / 2) ・ sin (θ / 2)
It can be expressed.

Since the sample 5 which is a magnetic material due to magnetostriction expands and contracts uniformly in the uniform magnetic field region along the direction of the magnetic field generated by the coil 4 (the extending direction of the sample 5), δ = δ ₁ = δ ₂ Then,
ΔS = 2 · δ / cos (θ / 2) + δ · cos (θ / 2) −δ ₃
δ ₃ = 2 ・ δ ・ tan (θ / 2) ・ sin (θ / 2)
And
ΔS = 2 · δ / cos (θ / 2) + δ · cos (θ / 2) -2 · δ · tan (θ / 2) · sin (θ / 2)
It becomes.

from now on,
δ = ΔS / (2 / cos (θ / 2) + cos (θ / 2) −2 · tan (θ / 2) · sin (θ / 2))
It becomes.

The magnetostriction to be obtained here is represented by ΔL / L _0, where ΔL is the amount of displacement in the horizontal direction (the extending direction of the sample 5) between the first and second target points 15 and 16.

And ΔL, which is the amount of displacement in the horizontal direction (extension direction of the sample 5) between the first reference point 15 and the second reference point 16, is the horizontal direction of the first reference point 15 (extension direction of the sample 5). a displacement [delta] ₁ because the sum of the displacement [delta] ₂ in the horizontal direction of the second reference points 16 (extending direction of the sample 5),
ΔL = δ ₁ + δ ₂
And
As before, assuming δ = δ ₁ = δ ₂ ,
ΔL = 2 · δ. From the above equation, ΔL = 2 · ΔS / (2 / cos (θ / 2) + cos (θ / 2) -2 · tan (θ / 2) · sin (θ / 2))
It becomes.

  Accordingly, the magnetostriction can be calculated from the displacement ΔS between the first and second target points 15 and 16 measured by the optical measuring means 11 using the above formula.

  As described above, the present invention provides an optical measuring means for measuring the amount of displacement between the first reference point 15 and the second reference point 16 in the uniform magnetic field region on the surface of the sample 5 placed in the magnetic field. 11 is a magnetostriction measuring method (magnetostriction measuring apparatus 1) for measuring the magnetostriction of the sample 5 by measuring at 11, and the light radiated from the optical measuring means 11 is reflected at the first gage 15 at the first reflector. 9 is reflected toward the second point 16, reflected at the second point 16 by the second reflector 10 toward the first point 15, and optically reflected at the first point 15 by the first reflector 9. It is configured to be reflected to the measuring means 11.

  Therefore, in the present invention, the displacement between two points in the uniform magnetic field region can be measured simultaneously by performing the measurement using the optical measuring means 11 only once, so that the magnetostriction of the sample 5 can be accurately measured. can do.

  In the magnetostriction measuring method (magnetostriction measuring apparatus 1) of the present invention, the light radiated from the optical measuring means 11 is reflected by the first reflector 9 toward the second reflector 10, and the second reflector 10 is reflected. Are reflected toward the first reflector 9 and reflected by the first reflector 9 toward the optical measuring means 11. The first reflector 9 and the second benchmark 16 provided at the first gage 15 2 and the second reflector 10 provided in FIG. 1, and as shown in FIGS. 1 and 2, at a predetermined angle (here, θ / 2) in the horizontal direction with respect to the extending direction of the sample 5. For example, as shown in FIG. 4, the optical measurement is performed obliquely at a predetermined angle in a direction perpendicular to the extending direction of the sample 5. Light may be emitted from the means 11.

  As shown in FIGS. 1 and 2, when the yokes 12 and 13 are connected to the sample 5, the optical measuring means 11 is directed obliquely with respect to the extending direction of the sample 5 while avoiding the yokes 12 and 13. It is possible to prevent the light irradiated from the optical measuring means 11 from being blocked by the double yoke 14 by irradiating the light from the light.

  As described above, in the present invention, the amount of displacement between the first reference point 15 and the second reference point 16 in the uniform magnetic field region on the surface of the sample 5 placed in the magnetic field is optically measured. In the magnetostriction measurement method (magnetostriction measuring apparatus 1) for measuring the magnetostriction of the sample 5 by measuring at 11, the light emitted from the optical measuring means 11 is converted into the second reference point 16 at the first reference point 15. In the uniform magnetic field region because it is reflected toward the first target point 15 at the second target point 16 and reflected to the optical measuring means 11 at the first target point 15. The amount of displacement between the two points can be measured simultaneously, and the magnetostriction of the sample 5 can be measured with high accuracy.

  Further, in the present invention, light is emitted from the optical measuring means 11 obliquely with respect to the extending direction of the sample 5 while avoiding the yokes 12 and 13 connected to the sample 5, so Even when 14 is connected, the magnetostriction of the sample 5 can be measured, and the magnetostriction of the sample 5 can be measured with higher accuracy.

DESCRIPTION OF SYMBOLS 1 Magnetostriction measuring apparatus 2 Casing 3 Coil holder 4 Coil 5 Sample 6 Sample holder
7,8 Aperture 9 First reflector
10 Second reflector 11 Optical measuring means
12,13 York 14 Double yoke
15 1st mark 16 2nd mark

Claims (4)

Magnetostriction measuring method for measuring magnetostriction of sample by measuring displacement amount between first and second target points in uniform magnetic field region on sample placed in magnetic field by optical measuring means In
The first and second target points are provided in a uniform magnetic field region where the magnetic field formed on the center side of the magnetic field generated by the coil is uniform,
The light emitted from the optical measuring means is reflected by the first reference point toward the second reference point, reflected by the second reference point toward the first reference point, and the optical measurement means by the first reference point. A method of measuring magnetostriction, which is reflected to the surface.   2. The magnetostriction measuring method according to claim 1, wherein light is emitted from the optical measuring means obliquely with respect to the extending direction of the sample while avoiding a yoke connected to the sample. A magnetostriction measuring apparatus for measuring magnetostriction of a sample by measuring a displacement amount between the first and second target points in a uniform magnetic field region on a sample placed in a magnetic field by an optical measuring means. In
The first and second target points are provided in a uniform magnetic field region where the magnetic field formed on the center side of the magnetic field generated by the coil is uniform,
While providing a 1st reflector in the 1st standard point, providing a 2nd reflector in the 2nd standard point,
Light emitted from the optical measuring means is reflected by the first reflector toward the second reflector, reflected by the second reflector toward the first reflector, and optical measuring means by the first reflector. The magnetostriction measuring apparatus, wherein the first reflector and the second reflector are arranged so as to be reflected toward the surface. The optical measurement means is arranged so that light emitted from the optical measurement means is incident on the first reflector obliquely with respect to the extending direction of the sample, avoiding a yoke connected to the sample. The magnetostriction measuring apparatus according to claim 3.

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