JPH07104046A - Magnetostriction measuring device - Google Patents

Abstract

PURPOSE:To measure magnetostriction smaller than the conventional one by one digit or more. CONSTITUTION:An alternating signal is applied to a first coil 2 wound cylindrically to generate alternating magnetic field in the inner space of the coil 2. A magnetic substance sample 3 is clamed by one pair of non-magnetic substance plates and held. The sample 3 is disposed in the substantially central part in the space surronded by the coil 2 by a sample holding member in such a manner that the direction of the surface where the sample 3 is clamped agrees with the winding direction of the first coil 2. In order to detect the magnetic characteristic in the vicinity of the sample 3, in the periphery of a part for clamping the sample 3 of one pair of non-magnetic plates, second coils 4, 5 fixed to the sample holding member are disposed. A light displacement meter 6 is provided, which is adapted to apply light beam to the end surface 3t of the sample 3 clamped between one pair of non-magnetic substance plates and detect the displacement of the end surface 3t of the sample 3 as magnetostriction from its reflected light. The relationship between the magnetic characteristic of the vicinity of the sample 3 and the amount of magnetostriction produced in the sample 3 under the magnetic characteristic condition is obtained from the induced voltage output obtained in the second coils 4, 5 and an output signal of the light displacement meter 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring magnetostriction of a magnetic material, and more particularly to an apparatus suitable for measuring extremely small magnetostriction.

[0002]

2. Description of the Related Art Magnetic materials such as iron and steel are
The acicular domains, which are the smallest magnets, are irregularly arranged and do not exhibit magnetism, but when the magnetic body is placed in a magnetic field, the acicular domains are aligned along the direction of the magnetic field, and Is magnetized to become a magnet. At this time, it is known that magnetostriction occurs in the magnetic body. Therefore, when the magnetic body is placed in an alternating magnetic field, the magnetic body vibrates due to magnetostriction.

Vibration due to magnetostriction of the magnetic material is considered to occur as follows. The magnetization of the magnetic body changes depending on the direction of the magnetic field in which it is placed. Therefore, when the magnetic body is placed in an alternating magnetic field as shown in FIG. 10A, the direction of magnetization of the magnetic body is reversed at a repetition rate twice the repetition frequency of the alternating magnetic field. Upon reversal of the magnetization direction, the needle-shaped magnetic domains 101 rotate as shown in FIG. 10B to reverse their magnetic poles.

As can be seen from FIG. 10B, with the reversal of the needle-shaped magnetic domains, the needle-shaped magnetic domains are in the horizontal position and in the vertical position. Therefore, it is considered that the magnetic substance is distorted by these positional changes. Since the rotation of the magnetic domain is caused by the alternating magnetic field, the magnetostriction of the magnetic substance placed in the alternating magnetic field is 2 times the repetition frequency of the alternating magnetic field.
It becomes the vibration distortion based on the double frequency.

Conventionally, the following method has been used as a method for measuring the magnetostriction of this magnetic material. That is, according to this method, as shown in FIG. 11, a mirror 1 in which a sample 102 made by flattening and thinning a magnetic material is provided with an inclination.
03, and this sample with a mirror is placed in the internal space of a coil (solenoid coil) 107 wound in a cylindrical shape shown by a dotted line in the figure. Then, an alternating current is passed through the coil 107 to generate an alternating magnetic field (alternating magnetic flux φ), and the sample 1
02 causes magnetostriction.

In this state, the light beam 105 is emitted from the light source 104 to the mirror 103 attached to the sample 102, and the reflected light is received by the light receiving section 106 to measure the magnitude of magnetostrictive vibration. . The measurement principle is shown in FIG.
As shown in, the mirror 103 attached to the magnetic material sample 102.
The fact that the reflected light has a divergence angle θ according to the amount of magnetostriction when the beam 105 is incident on is used.

[0007]

By the way, such vibration due to magnetostriction of the magnetic material causes various noises such as appearing as a humming noise in a motor or a transformer. Therefore, there is a demand for a material having as small a magnetostriction as possible, and its development is in progress. And recently, the amount of magnetostriction is 10 ⁻⁷ per 1 m.
The possibility of birth of materials that are pressed down to around 10 ^-9 m is emerging.

By the way, such a small magnetostriction of the magnetic material must be confirmed by measuring the magnitude of the magnetostriction. For that purpose, it must be possible to measure such a very small magnetostriction.

However, the conventional strain measuring device using a mirror is not a method of directly measuring the magnetostriction itself of a sample, but the reflected light has a predetermined spread angle θ according to the amount of magnetostriction. It is possible to measure magnetostriction up to about 10 ^-7 m per 1 m of material because it uses the method of indirectly measuring the amount of magnetostriction. , Small magnetostriction could not be measured accurately.

Further, since the system receives the reflection of light from the mirror attached to the sample, it is difficult to firmly fix the sample. For this reason, for example, when trying to measure the magnetostriction in the flat plane direction of a sample cut into a flat and thin shape, the sample is affected by the magnetostriction in the thickness direction of the sample, causing the sample to laterally shake, etc. Strain measurement is disabled.

Moreover, since the mirror is attached to the sample, the magnetostriction generated on the sample is affected by the amount of the attached mirror, which is also a hindrance for accurate measurement of smaller magnetostriction. .

Further, in the case of the conventional example shown in FIG. 11, the mirror 103 to which the sample is attached is irradiated with the light from the light source 104 outside the coil 107, and the reflected light is reflected by the coil 1.
Since the light receiving element 106 provided outside 07 needs to receive light, the coil 107 has the sample 1
In the vicinity of 02, a space for guiding the light must be provided without winding the wire. Therefore, the coil 107
The alternating magnetic field generated in the winding direction becomes uneven in the vicinity of the sample 102, and it is difficult to arrange the magnetic characteristic environment in the vicinity of the sample, which is important for accurate measurement of magnetostriction, to be the desired one. Met.

In view of the above points, the present invention makes it possible to directly measure the magnetostriction generated in a magnetic material sample,
It is an object of the present invention to provide a magnetostriction measuring device capable of measuring a smaller magnetostriction.

[0014]

In order to solve the above-mentioned problems, the magnetostriction measuring apparatus according to the present invention corresponds to the reference numerals of the embodiments to be described later, and a first magnetic field measuring apparatus for generating a magnetic field wound in a cylindrical shape. Coil 2 and an alternating signal generator 11 for generating an alternating signal to be supplied to the first coil 2 in order to generate an alternating magnetic field in the internal space of the first coil 2.
A pair of non-magnetic material plates 31 for holding the magnetic material sample 3 therebetween,
32, and the magnetic material sample 3 is sandwiched between the first coil 2 and the first coil 2 so that the direction of the sandwiched surface of the magnetic material sample 3 coincides with the winding direction of the first coil 2. A sample holding member 30 for disposing the sample 3 and a pair of non-magnetic material plates 31 for detecting magnetic characteristics in the vicinity of the sample 3,
The second coil 4, 5 fixed to the sample holding member 30 and the magnetic material between the pair of non-magnetic material plates 31, 32 of the sample holding member 30 around the portion of the sample holding member 30 that sandwiches the sample 3. An optical displacement meter 6 for irradiating the end face 3t of the sample 3 or a reflector attached to the end face 3t with a light beam and detecting the displacement of the end face 3t of the magnetic material sample 3 from the reflected light,
Based on the induced voltage output obtained in the second coils 4 and 5 and the output signal of the optical displacement meter 6, the magnetic characteristics in the vicinity of the magnetic material sample 3 and the magnetostriction generated in the magnetic material sample 3 under the magnetic characteristic conditions. It is characterized in that the relationship with the amount of is obtained.

In processing the outputs of the second coils 4 and 5 and the optical displacement meter, the induced voltage output obtained in the second coil 2 and the output signal of the optical displacement meter 6 are respectively supplied. An amplifier circuit 21 for amplifying, an A / D converter 22 for converting the induced voltage output from the amplifier circuit 21 and the amplified signal of the output signal of the optical displacement meter 6 into a digital signal,
A buffer memory 23 for storing each digital signal of the induced voltage output from the A / D converter 22 and an output signal of the optical displacement meter, and a trigger timing synchronized with the alternating magnetic field for each digital signal of the buffer memory 23. As a reference, an averaging circuit 24 that performs an averaging calculation process.
And the magnetic field in the vicinity of the magnetic material sample 3 and the magnetic property conditions under the magnetic property conditions from the averaging processing output of the induced voltage output from the averaging circuit 24 and each digital signal of the output signal of the optical displacement meter. The relationship with the amount of magnetostriction generated in the magnetic material sample 3 may be obtained.

[0016]

In the measuring device of the present invention having the above structure,
The magnetic material sample 3 is sandwiched by a pair of non-magnetic material plates 31 and 32, and is arranged in a space in the first coil 2 in which an alternating magnetic field is generated in a state where displacement in that direction is limited. Due to the alternating magnetic field, the magnetic material sample 3 has a pair of non-magnetic material plates 31,
Direction of the surface sandwiched by 32, that is, the first coil 2
Displacement due to magnetostriction occurs in the winding direction of the
t exhibits vibration according to the displacement due to the magnetostriction.

The optical displacement meter 6 irradiates the end face 3t of the sample 3 with a light beam from the space in the winding direction of the first coil 2 and uses the reflected light to vibrate and displace the end face 3t of the sample 3. Obtain an output signal according to the quantity.

The magnetic field in the vicinity of the magnetic material sample 3, the magnetic flux density in the space, the magnetic permeability of the sample, and the like are obtained based on the induced voltage output obtained in the second coils 4 and 5.

From the above output results, the relationship between the magnetic characteristic conditions such as the magnetic field and the magnetic flux density and the magnetostriction can be obtained.

Although noise is included in the induced voltage output of the optical displacement meter and the coil, an averaging circuit 24 is provided, and in this circuit 24, averaging calculation processing is performed at a trigger timing synchronized with the alternating magnetic field. . Then, noise components other than the magnetostrictive component synchronized with the alternating magnetic field in the output of the optical displacement meter 6 and noise components other than the induced voltage component synchronized with the alternating magnetic field are suppressed, and the magnetostrictive component synchronized with the target alternating magnetic field is suppressed. Alternatively, only the induced voltage component synchronized with the alternating magnetic field is obtained.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a magnetic strain measuring device for magnetic materials according to the present invention will be described below with reference to the drawings.

FIG. 1 shows the entire mechanical structure and signal processing system of the mechanical portion of the magnetostriction measuring apparatus of this example.
The mechanical configuration of the mechanism section shown in FIG. 1 shows a principle configuration, and a detailed configuration example thereof is as shown in FIG. FIG. 2A is a plan view (partially shown as a cross section) of the mechanical section of the measurement apparatus of this example, and FIG. 2B is a side view (partially shown as a cross section) of the mechanical section of the measurement apparatus of this example. It is).

First, in FIG. 1, reference numeral 1 is a hollow cylindrical double glass tube. The glass tube 1 has a shape in which concentric cylindrical glass walls are connected at their ends in the tube axis direction. A coil 2 for generating an alternating magnetic field is provided on the outer periphery of the glass tube 1 except for both ends in the tube axis direction.
Is wound into a solenoid coil. Then, the magnetic material sample 3 is placed at a substantially central position in the cylindrical space in the glass tube 1.

In the case of this example, the magnetic material sample 3 has a flat rectangular thin plate shape, and the thickness, width, and length thereof are determined in advance. The sample 3 is held by the sample holding means 30 to be described later and placed in the glass tube 1 in a state where the plate surface direction thereof coincides with the tube axis direction of the glass tube 1.

The alternating voltage from the alternating signal generator 11 is supplied to the alternating magnetic field generating coil 2 through the amplifier 12. As a result, the alternating current i flows through the coil 2,
An alternating magnetic field in the tube axis direction is generated in the cylindrical space of the glass tube 1.

By the way, since a relatively large current i is passed through the coil 2, heat is generated. Therefore, in the apparatus of this example, cooling water is caused to flow in the double wall of the glass tube 1 to prevent excessive heat generation.

In order to make this cooling water flow, the glass tube 1 is provided with an opening 1a so as to project from a part of one end side in the tube axis direction and the other end side in the tube axis direction. Of the opening 1b so as to project from that position at a position 180 degrees apart from the position of the opening 1a.
Is provided. Then, as shown in the figure, the glass tube 1 is placed in a horizontal position with the opening 1a facing upward and the opening 1b facing downward, and cooling water is injected from the opening 1a. The cooling water goes through all the parts in the glass tube 1 and is drained from the opening 1b.

When the magnetostriction of the sample 3 is measured, the magnetic field in the vicinity of the sample 3 or the magnetic flux (magnetic flux density) passing through the sample 3 is known, and the magnetostriction generated under the magnetic characteristic conditions of the magnetic flux or the magnetic field is measured. There is a need.
Therefore, the coil block CB is provided to measure the magnetic characteristics in the vicinity of the sample 3.

This coil block CB is, in this example,
As will be described later, it comprises a search coil 4 for measuring a magnetic flux passing through the sample 3 and a correction coil 5 for measuring a magnetic field as close to the sample 3 as possible. The detailed configuration will be described later.

In the above structure, when an alternating current i is passed through the coil 2, an alternating magnetic field is induced in the tube axis direction of the glass tube 1, and this alternating magnetic field causes the current in the magnetic material sample 3 as described above. Magnetostriction is generated that oscillates at twice the frequency of i. In this case, since the sample 3 is a flat rectangular thin plate, this magnetostriction appears as expansion and contraction in the plate surface direction (tube axis direction). That is, the end surface 3t of the thickness portion of the sample 3 is displaced in the tube axis direction according to the expansion and contraction of the sample 3.

In this example, the end face 3t of the sample 3 is
Of the sample 3 by measuring the displacement of
The magnetostriction of is directly measured. Since the displacement is measured using light, there is almost no electromagnetic effect.

In FIG. 1, 6 is an optical displacement meter, and 6a
Is the probe. The probe 6a is made of a non-magnetic material. The optical displacement meter 6 of this example includes a probe 6
A light beam 7 is emitted from a and reflected light is obtained from this probe 6a. In this example, the end face 3t of the sample 3 is irradiated with the light beam emitted from the probe 6a. The optical displacement meter 6 receives the reflected light from the end face 3t via the probe 6a, converts the displacement of the end face 3t into a voltage change, and obtains it as an output signal Vλ.

The probe 6a is attached to the end surface 3t of the sample 3.
For example, a minute reflector may be attached to reflect the light beam from.

Next, with reference to FIGS. 2 to 4, a more detailed structure of the above-mentioned mechanical portion will be described. 3 is an AA cross-sectional view of FIG. 1, and FIG. 4 is an enlarged cross-sectional view of the central portion of the mechanism portion.

As shown in FIG. 2, the outside of the glass tube 1 is
It is covered with a cylindrical case 7 made of Bakelite. The housing 7 is fixed to the base member 8. Glass tube 1
The cooling water inlets / outlets 1 a and 1 b are led to the outside of the housing 7. Further, both ends of the casing 7 in the tube axis direction are attached to the sample 3
It is an opening for entering and exiting and for inserting the probe 6a of the optical displacement meter 6.

The magnetic material sample 3 is held by the sample holding member 30. That is, as shown in FIGS. 2 and 4, in this example, the magnetic material sample 3 is in the shape of an elongated flat thin plate, and a pair of non-magnetic material plates 31 and 31 similarly configured in the shape of an elongated thin plate. It is sandwiched and held by 32. The non-magnetic plates 31 and 32 are preferably as heavy as possible in order to securely hold the magnetic sample. In this example,
Alumina porcelain is used.

In the case of this example, the dimensions of the nonmagnetic plates 31 and 32 are, for example, thickness × width × length = 2 (mm).
It is set to x31 (mm) x277 (mm). Also,
The dimensions of the sample 3 are, for example, thickness × width × length = 1 (mm)
It is set to × 30 (mm) × 280 (mm). That is, the sample 3 is slightly longer than the non-magnetic material plates 31 and 32, and the portion thereof protrudes toward the probe 6a side.
The end surface 3t of the projecting portion is displaced due to magnetostriction. Therefore, it is advisable to attach a reflector to the end face 3t.

One end side of the pair of non-magnetic plates 31, 32 in the length direction is fixed by a holding arm 33. in this case,
The holding arm 33 fixes the non-magnetic plates 31 and 32 with the sample 3 in between, for example, with a screw or the like. The other ends of the pair of non-magnetic plates 31, 32 in the length direction are not fixed and are placed on a holding table 34 fixed to the housing 7 or the base 8 in the measurement state. The sample 3 can be exchanged by loosening the screw and releasing the fixed holding of the pair of nonmagnetic plates 31 and 32 by the holding arm 33.

The holding arm 33 holds the holding arm pedestal 35 in order to lead the sample 3 out of the glass tube 1 and exchange it.
On the other hand, it is slidably engaged in the horizontal direction along the tube axis direction of the glass tube 1. Sliding between the holding arm 33 and the holding arm pedestal 35 can be performed very easily, and after the sliding, the holding arm 33 is moved by a screw or the like.
Are fixed to the pedestal 35.

The holding arm cradle 35 is made of a heavy member, and in this example, it is made of stainless steel.
In order to further increase the horizontal movement distance, the holding arm pedestal 35 is also slidably attached to the base 34 in the same direction as the holding arm 33, and can be fixed by a screw or the like. It is configured. The handle 36 is used when the holding arm pedestal 35 slides.

In this case, in the state of being held by the non-magnetic material plates 31 and 32, the magnetic material sample 3 can freely expand and contract due to magnetostriction in the plate surface direction (the tube axis direction of the glass tube 1). However, since it is held by the non-magnetic material plates 31 and 32, the expansion and contraction of the magnetic material sample 3 is restricted in the thickness direction.

Next, the structure of the coil block CB will be described. The search coil 4 is wound in a solenoid coil shape with the tube axis direction of the glass tube 1 as a winding direction, and when the sample 3 is installed in the space inside the glass tube 1, the sample 3 is almost wound around the coil 4. It is supposed to be located in the center. This coil 4 is a sectional view taken along the line AA of FIG.
And as shown in FIG. 4 of the enlarged view of the main part, it is wound around the hollow cylindrical bobbin 41 made of a non-magnetic material, and in the measurement state,
The sample 3 is in a state of being inserted into the hollow portion of the bobbin 41.

The size of the bobbin 41 is selected such that the cross-sectional area of the hollow part thereof is slightly larger than the cross-sectional areas of the non-magnetic material plates 31 and 32 holding the sample 3 so that the replacement of the sample 3 will not be hindered. Has been done. The bobbin 41 is fixed to one of the non-magnetic plates 31 and 32, for example, at a substantially central position in the length direction of the plate 31 by adhesion or the like.

The correction coil 5 for measuring the magnetic field as close as possible to the sample 3 is constructed by winding a wire around the non-magnetic material cores 51 and 52 such as Mylar and winding the wire. It is fixed to the outer peripheral part. In this example, as shown in FIG. 3, the correction coil 5 is composed of cores 51 and 52 in which wire rods are wound in series above and below the sample 3 on the outer peripheral portion of the search coil 4, respectively. Configured to be connected to. The winding direction of the correction coil 5 also matches the tube axis direction of the glass tube 1. Further, the cross-sectional areas of the cores 51 and 52 are set to a predetermined value A in order to obtain the magnetic flux density. The correction coil 5 may be an air core instead of a non-magnetic core wound with a wire.

As shown in FIG. 2, the lead wire end portions 4L and 5L of the coils 4 and 5 from the coil block CB are also shown.
Is guided from the inside of the glass tube 1 to the space between the housing 7 and the outer wall of the glass tube 1, and is connected to an output terminal (not shown) provided outside the housing 7 Is connected to an internal terminal (not shown).

In this case, the magnetic material sample 3 is installed in the glass tube 1 in the tube axis direction at the electrical center position in the winding direction of the coil 2 wound around the glass tube 1 and the tube of the sample 3. The position is set so as to coincide with the center (electrical center) position in the axial direction. This is because when it is not at the electrical center, the sample 3 itself moves and changes its position in the tube axis direction due to the alternating magnetic field, and only magnetostriction cannot be correctly measured.

That is, when the magnetic material sample 3 has, for example, a polycrystalline structure, the crystals forming the magnetic domains have various sizes, and the sample is placed in a magnetic field to exhibit magnetism. When the magnetic domains are aligned with each other, it is common that the electrical center position and the physical center position of the sample do not match due to the difference in the size of the magnetic domains. For this reason, even if the physical central position is aligned with dimensional accuracy, the electric central position is not reached.

If the coil 2 also has winding irregularities, the physical center position and the electrical center position in the coil winding direction do not match. Particularly, in the case of this example, the optical displacement meter 6
In order that the gap between the tip of the probe 6a and the end face 3t of the sample 3 can be seen from the window 7W provided in the housing 7, the corresponding portion of the coil 2 is wound so as to leave a gap. Because of the lines, the physical center position and the electrical center position of the coil 2 do not match. This also applies to the conventional mirror method.

Therefore, in this example, the non-magnetic plates 31, 3 are used.
The sample 3 is fixed to the holding arm 33 in a state of being sandwiched by 2 and is placed at a substantially physical center position in the glass tube 1, and then a predetermined alternating current is applied to the coil 2 before the actual measurement is started. . At this time, the screw for fixing the holding arm 33 to the pedestal 35 is loosened, and the holding arm 33 is attached to the pedestal 35.
Be slidable.

Then, the sample 3 attempts to vibrate and move to the center so that the electrical center position and the center position of the coil 2 coincide with each other. As mentioned above,
Sliding between the holding arm 33 and the holding arm receiving base 35 can be performed very easily. Therefore, if the arm 33 is not fixed to the receiving base 35, according to the movement of the sample 3 itself, The pair of non-magnetic plates 31 and 32 sandwiching the sample 3 including the holding arm 33 vibrates left and right, and after a predetermined time, at the position where the electrical center position of the sample 3 and the central position of the coil 2 coincide with each other. Stop the movement. After the elapse of this predetermined time, the holding arm 33 is fixed to the pedestal 35 with a screw.

In this way, the electrical center position of the sample 3 can be aligned with the center position of the magnetic field of the coil 2. In this case, the magnitude of the current supplied to the coil 2 for alignment need not be a large current as in the case of measuring magnetostriction, and the holding member 3 that holds the sample 3
It may be a value that can move 0.

Next, before starting the actual measurement, the optical displacement meter 6
Calibrate. The optical displacement meter 6 generally measures the displacement of a light-irradiated portion from the intensity change of reflected light when light is irradiated. The intensity of the reflected light is inversely proportional to the square of the distance between the probe 6a of the optical displacement meter 6 and the measurement target site, but the displacement is measured by measuring the portion with good linearity as the photoelectric conversion output characteristic of the optical displacement meter 6. use. FIG. 5 shows an example of the output characteristic of the optical displacement meter 6 of this example, and the linearity becomes good when the output is around 5V.

The optical displacement meter 6 is calibrated in the following manner with the distance between the probe 6a and the end surface 3t of the sample 3 being the measurement target site being set at this position with good linearity.

That is, in this example, the optical displacement meter 6
Are attached to the sliding movement member 60, as shown in FIG. The sliding movement member 60 includes a micrometer 61, and by adjusting the micrometer 61,
The tip of the probe 6a is configured to be slidable in the tube axis direction of the glass tube 1 by the distance indicated by the meter. Then, the micrometer 61 is operated to change the distance between the tip of the probe 6a and the end surface 3t of the sample 3 and first adjust the output of the optical displacement meter 6 to a position with good linearity.

In this case, the photoelectric conversion output of the displacement caused by magnetostriction of the optical displacement meter 6 is several hundred mV, which is very small with respect to the direct current component of 5 V. The amount of displacement due to strain cannot be amplified to an appropriate value. Therefore, in this example, the DC component of the output of the optical displacement meter 6 is removed as an offset in accordance with the alignment of the output signal of the micrometer 61 to a position having good linearity.

Next, at this position, when the tip of the probe 6a is moved by a predetermined distance by operating the micrometer 61, the output voltage is detected and the output is calibrated. For example, if the output is a volt when moved by 200 μm, it becomes a / 2 when moved by 1 μm.
Calibrate so that it will be 00 volts.

As the optical displacement meter 6, a light beam having a beam spot diameter larger than the thickness of the sample 3 is used. This is because when using a beam having a narrowed beam diameter, irregularities existing on the end face 3t of the sample 3 irradiated with the beam may be detected as strain.

As described above, after the electrical center positions of the sample 3 and the magnetic field generating coil 2 have been aligned and the calibration of the optical displacement meter 6 has been completed, the coil 2 has a frequency of, for example, 50 H.
An alternating current i of z, 200 Hz, 400 Hz and an effective value of about 1 A is passed. Then, an alternating magnetic field is induced in the tube axis direction of the glass tube 1, and the alternating magnetic field causes magnetostriction in the magnetic material sample 3 that vibrates at a frequency twice the frequency of the current i as described above. In this case, this magnetostriction appears as expansion and contraction in the plate surface direction (tube axis direction) of the sample 3, and the end surface 3t is displaced in the tube axis direction according to the magnetostriction. The optical displacement meter 6 receives the reflected light from the end face 3t via the probe 6a, converts the displacement of the end face 3t into a voltage change, and obtains it as an output signal Vλ.

Further, a voltage VB corresponding to the change of the magnetic flux φ passing through the bobbin 41 is obtained between the both ends 4a, 4b of the search coil 4 by the alternating magnetic field. The magnetic flux passing through the bobbin 41 is the same as the magnetic flux passing through the portion inside the bobbin except the sample 3.
It consists of the sum of the magnetic flux passing through.

Further, between both ends 5a, 5b of the correction coil 5, a voltage VH corresponding to the change in magnetic flux in the space portion of the sum of the sectional areas A of the cores 51, 52 is obtained.

The output signal Vλ from the optical displacement meter 6 and the voltages VB and VH obtained by the search coil 4 and the correction coil 5
Are respectively in the signal conditioner 21,
While being amplified, unnecessary high frequency components and low frequency components are removed.

The output signals Sλ, SB, SH resulting from processing the displacement output Vλ, the voltage VB, and the voltage VH by the signal conditioner 21 as described above are supplied to the A / D converter 22, and the digital signal Dλ, DB, DH
And is temporarily stored in the buffer memory 23.
The digital signals Dλ, DB stored in the memory 23,
The DH is supplied to the averaging circuit 24.

The averaging circuit 24 carries out a process for obtaining an average based on the trigger timing. In the case of this example, the alternating signal from the alternating signal generator 11 is supplied to the trigger generator 13 to synchronize with the trigger signal T.
G is obtained from this, and this trigger signal TG is supplied to the averaging circuit 24.

In the averaging circuit 24, each digital signal is averaged by being triggered by this trigger signal TG synchronized with the alternating signal. Each input signal of the averaging circuit 24 includes noise components other than the target displacement and voltage synchronized with the alternating signal, but this averaging process causes unnecessary noise components other than the component synchronized with the alternating signal. To be removed.

FIG. 6A shows the output signal of the optical displacement meter 6 when the averaging circuit 24 is input, and FIG. 6B shows the output signal Eλ after the averaging process. Further, FIG. 6C is an example of an averaging processing output VB of the voltage VB from the search coil 4 on the same time scale. Similarly, the averaging output EH of the voltage VH from the correction coil 5 is also noise-removed.

In this way, in the averaging circuit 24, the noise-removed outputs Eλ, EB, EH are supplied to the signal processing circuit 25 composed of a microcomputer. In this signal processing circuit 25, the magnetic field H near the sample 3 is obtained from the output EH. That is, the output EH obtained from the output voltage of the coil 5 is the magnetic flux φ of the space portion occupied by the cores 51 and 52.
(Dφ / dt: t is time),
From this, the magnetic flux φ passing through the space occupied by the cores 51, 52
Is required. Since the cross-sectional areas of the portions of the cores 51 and 52 are known, the magnetic flux density Ba of the space near the sample 3 is obtained from this magnetic flux φ, and the magnetic permeability of the space is also known. A magnetic field H in the vicinity is required.

Further, the magnetic flux passing through the sample 3 is obtained from the output EB and the magnetic flux density Ba of the space, and the magnetic flux density Bs of the portion of the sample 3 is obtained from the cross-sectional area of the sample 3. That is, the output EB can be considered as the sum of the change in the magnetic flux passing through the space inside the bobbin 41 and the change in the magnetic flux passing through the sample 3. The magnetic flux of the space portion (the cross-sectional area is known) in the bobbin 41 can be obtained from the magnetic flux density Ba, and the voltage component caused by the change can also be obtained. As a result, the voltage corresponding to the change of the magnetic flux passing only the sample 3 portion can be obtained, and the magnetic flux passing the sample 3 portion can be obtained. Since the cross-sectional area of the sample 3 is known, the magnetic flux density Bs of the sample 3 portion can be obtained. Further, the magnetic permeability μ of the sample 3 can be obtained from the magnetic field H and the magnetic flux density Bs.

Further, the magnetostriction λ can be obtained from the output Eλ. Then, the relationship between the magnetic field H or the magnetic flux density B and this magnetostriction λ is obtained. The relationship is CR
It is displayed on the output device 26 such as a T display or a printer, or is output on a recording sheet.

FIG. 7A shows the obtained magnetic field H and magnetic flux density Bs, and FIG. 7B is a so-called magnetic hysteresis curve showing the relationship between the two. FIG. 8A shows the waveforms of the magnetic field H and the magnetostriction λ, and FIG. 8B shows the relationship between the two.
That is, the relationship of magnetic field-magnetostriction (H-λ) is shown. 7 and 8 show an alternating current of 200 Hz,
This is a case where a current of 0.6 A was passed through the coil 2 and the magnetostriction of the novel silicon steel plate was measured.

Similarly, FIG. 9A shows the waveforms of the magnetic flux density Bs and the magnetostriction λ, and FIG. 9B shows the relationship between the two.
That is, the relationship between magnetic flux density and magnetostriction (B-λ) is shown. In the example of FIG. 6, an alternating current of 400 Hz and 1.12 A is applied to the coil 2.

As a result of the measurement of the strain of the magnetic material by the inventor of the present invention, according to the present invention, it is possible to measure the magnetostriction up to 10 ⁻⁹ m when the sample is 1 m. It has been found.

[0072]

As described above, according to the present invention, the magnetostriction is not indirectly measured by using the mirror as in the conventional magnetostriction measuring apparatus, but is directly measured by using the optical displacement meter. Moreover, since the magnetostriction is measured as the displacement of the end surface of the sample, a smaller magnetostriction can be measured.

In this case, the output of the optical displacement meter includes not only the displacement of the end surface of the sample due to magnetostriction but also the noise component. In the present invention, the noise in the output of this optical displacement meter is Is removed by an averaging process that triggers in synchronization with the alternating magnetic field applied to. Therefore, the magnetostriction can be measured with high accuracy.

Further, in the device of the present invention, unlike the conventional method of attaching a mirror to a sample, an extra one is not added to the sample, and in this respect also, more accurate measurement of magnetostriction can be achieved. It will be possible.

Further, since the magnetic material sample is held by being sandwiched between a pair of plates made of non-magnetic material, the positional fluctuation of the magnetic material sample itself and the displacement other than the intended displacement direction by the optical displacement meter are limited. Therefore, the measurement accuracy can be improved in this respect as well.

Further, the coil block for measuring the magnetic characteristics in the vicinity of the sample can be attached by using a pair of non-magnetic material plates, and the displacement measurement can be performed by using an optical beam with an optical displacement meter. Therefore, it is not necessary to consider the coil winding portion. Therefore, it becomes possible to accurately know the magnetic characteristics near the sample.

According to the configuration of the present invention described above,
Compared with the conventional magnetostriction measuring method explained at the beginning, 1
It was confirmed that it was possible to measure magnetostriction that was smaller than an order of magnitude.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of a magnetostriction measuring apparatus according to the present invention.

FIG. 2 is a diagram showing a configuration example of a mechanical portion of an embodiment of the magnetostriction measuring apparatus according to the present invention.

FIG. 3 is a diagram for explaining in detail a configuration of a main part of the example of FIG.

FIG. 4 is an enlarged cross-sectional view of the configuration of the main part of the example of FIG.

FIG. 5 is a diagram for explaining output characteristics of the optical displacement meter.

FIG. 6 is a diagram showing an example of an output signal waveform of each part of the embodiment of the magnetostriction measuring apparatus according to the present invention.

FIG. 7 is a diagram showing an example of waveforms of magnetic fields and magnetic flux densities obtained by the magnetostriction measuring apparatus according to the present invention and their relations.

FIG. 8 is a diagram showing an example of magnetic field and magnetostrictive waveforms obtained by the magnetostrictive measuring device according to the present invention, and their relationship.

FIG. 9 is a diagram showing an example of magnetic flux density and magnetostriction waveforms obtained by the magnetostriction measuring device according to the present invention, and their relationship.

FIG. 10 is a diagram for explaining a mechanism of magnetostriction generation.

FIG. 11 is a diagram for explaining an example of a conventional magnetostrictive measuring device.

[Explanation of symbols]

 1 Glass Tube 2 Coil for Generating Alternating Magnetic Field 3 Magnetic Sample 4 Searching Coil 5 Correction Coil 6 Optical Displacement Meter 11 Alternating Signal Generator 13 Trigger Signal Generator 22 A / D Converter 23 Buffer Memory 24 Averaging Circuit 25 Signal Processing Circuit 30 sample holding member 41 bobbin 31, 32 non-magnetic material plate 51, 52 core 61 micrometer

Claims (3)

[Claims] 1. A first coil for generating a magnetic field wound in a cylindrical shape, and an alternating signal supplied to the first coil for generating an alternating magnetic field in the internal space of the first coil. An alternating signal generator for generating and a pair of non-magnetic material plates for sandwiching and holding a magnetic material sample are provided,
With the direction of the sandwiched surface of the magnetic material sample coinciding with the winding direction of the first coil, the magnetic field is provided at substantially the center of the space surrounded by the first coil for magnetic field generation. A sample holding member for arranging a body sample, and in order to detect magnetic characteristics in the vicinity of the sample, the sample holding member is provided around the portion of the pair of non-magnetic plates that holds the sample. And the second coil fixed by the sample holding member and an end face of the magnetic sample between the pair of non-magnetic plates of the sample holding member or a reflector attached to this end face is irradiated with a light beam, and from the reflected light, An optical displacement meter for detecting the displacement of the end face of the magnetic material sample is provided, and the magnetic field near the magnetic material sample is detected from the induced voltage output obtained in the second coil and the output signal of the optical displacement meter. Characteristics and the above-mentioned magnetism under the condition of its magnetic characteristics Magnetostrictive measuring device was set to obtain the relationship between the amount of magnetostriction caused to the sample. 2. A first coil for magnetic field generation wound in a cylindrical shape, and an alternating signal supplied to the first coil for generating an alternating magnetic field in the internal space of the first coil. An alternating signal generator for generating and a pair of non-magnetic material plates for sandwiching and holding a magnetic material sample are provided,
With the direction of the sandwiched surface of the magnetic material sample coinciding with the winding direction of the first coil, the magnetic field is provided at substantially the center of the space surrounded by the first coil for magnetic field generation. A sample holding member for arranging a body sample, and in order to detect magnetic characteristics in the vicinity of the sample, the sample holding member is provided around the portion of the pair of non-magnetic plates that holds the sample. And the second coil fixed by the sample holding member and an end face of the magnetic sample between the pair of non-magnetic plates of the sample holding member or a reflector attached to this end face is irradiated with a light beam, and from the reflected light, An optical displacement meter for detecting the displacement of the end face of the magnetic material sample, an induced voltage output obtained in the second coil, and an amplifier circuit for amplifying the output signal of the optical displacement meter, and the amplifier circuit. The induced voltage output from the An A / D converter for converting an amplified signal of the output signal of the position meter into a digital signal; a buffer memory for storing each digital signal of the induced voltage output from the A / D converter and the output signal of the optical displacement meter; Each digital signal of the buffer memory is provided with an averaging circuit that performs averaging calculation processing with the trigger timing synchronized with the alternating magnetic field as a reference, and the induced voltage output and the output of the optical displacement meter from the averaging circuit. Magnetostriction measurement for obtaining the relationship between the magnetic characteristics in the vicinity of the magnetic material sample and the amount of magnetostriction occurring in the magnetic material sample under the condition of the magnetic characteristics from the averaging output of each digital signal. apparatus. 3. A first coil for generating a magnetic field wound in a cylindrical shape, and an alternating signal supplied to this first coil for generating an alternating magnetic field in the internal space of the first coil. An alternating signal generator for generating and a pair of non-magnetic material plates for sandwiching and holding a magnetic material sample are provided,
With the direction of the sandwiched surface of the magnetic material sample coinciding with the winding direction of the first coil, the magnetic field is provided at substantially the center of the space surrounded by the first coil for magnetic field generation. A sample holding member for arranging the body sample, and in order to detect a magnetic flux passing through the inside of the sample, the pair of non-magnetic material plates are wound around a portion sandwiching the sample, A second coil fixed to at least one of the non-magnetic plates and a magnetic flux passing through a space having a predetermined cross-sectional area in the vicinity of the sample are wound around the space portion as a core and are attached to the holding member. An optical beam is irradiated to the end face of the magnetic material sample or the reflection plate attached to this end face between the pair of non-magnetic material plates of the sample holding member and the third coil fixed thereto, and from the reflected light. , Detecting the displacement of the end face of the magnetic sample An optical displacement meter, and the induced voltage output obtained in the second and third coils,
An amplifier circuit for amplifying the output signal of the optical displacement meter, an A / D converter for converting the induced voltage output from the amplifier circuit and the amplified signal of the output signal of the optical displacement meter into a digital signal; A buffer memory for storing each digital signal of the induced voltage output from the A / D converter and an output signal of the optical displacement meter, and averaging each digital signal of the buffer memory with reference to the trigger timing synchronized with the alternating magnetic field. An averaging circuit for performing arithmetic processing is provided, and from the averaging output of the induced voltage output from the averaging circuit, the magnetic permeability of the magnetic material sample is obtained, and the magnetic characteristics in the vicinity of the magnetic material sample are obtained. From the averaging output of the output signal of the optical displacement meter and the magnetic characteristics in the vicinity of the magnetic material sample, the magnetic material sample is produced under the magnetic characteristics conditions. Magnetostrictive measuring device was set to obtain the relationship between the amount of magnetostriction that.