JP6934740B2 - Magnetization measurement method - Google Patents

Description

The present invention relates to a method for measuring magnetization.

The magnetization-magnetic field curve (JH curve) of the sample to be measured is measured in order to evaluate the saturation magnetization, residual magnetic flux density, coercive force, etc. of the sample to be measured made of a magnetic material such as a permanent magnet. As a method for measuring such a JH curve, a magnetic field is applied while sweeping with an exciting coil to magnetize the sample to be measured, and magnetization is generated from an induced electromotive force generated in a detection coil wound around the sample to be measured. There is a way to ask.

Japanese Patent Application Laid-Open No. 2013-50390 (Patent Document 1) describes a B coil for measuring the magnetic flux density of a permanent magnet and a magnetic field strength of the permanent magnet in a magnetic characteristic measuring sensor for measuring the magnetic characteristics of the permanent magnet. A technique is disclosed in which an H coil used for measuring the above and / or an M coil used for measuring the magnetization of a permanent magnet are wound coaxially around a permanent magnet.

On the other hand, when measuring the JH curve by magnetically saturationing a sample under test made of a permanent magnet having a large saturation magnetization such as a neodium iron boron (NdFeB) magnet, for example, a closed magnetic circuit using an iron core and an electromagnet. The method cannot apply a magnetic field of sufficient strength to magnetically saturate the sample under test. In such a case, a pulse magnetic field is applied to the sample to be measured to measure the JH curve.

According to Japanese Patent Application Laid-Open No. 2016-95264 (Patent Document 2), in a high magnetic field pulse excitation type magnetic property evaluation device, a magnetic field is applied to a coil provided around a sample in a state where the sample is sandwiched between a pair of sample holding rods. Then, a technique for measuring the magnetic properties of a sample is disclosed.

Japanese Unexamined Patent Publication No. 2013-50390 Japanese Unexamined Patent Publication No. 2016-95264

However, when the magnetic field is applied while being swept by the exciting coil to magnetize the sample to be measured and the magnetization is obtained from the induced electromotive force generated in the detection coil wound around the sample to be measured, there are the following problems. ..

For example, the influence of the eddy current generated in the sample to be measured when the magnetic field is applied while being swept cannot be ignored. Alternatively, if a yoke made of a ferromagnetic metal cannot be provided around the sample to be measured, the influence of the demagnetic field around the sample to be measured becomes large. Alternatively, when the coil for detecting the magnetization and the coil for detecting the strength of the magnetic field are arranged at intervals in the direction along the applied magnetic field, the measured magnetic field is actually applied to the sample to be measured. It does not match the magnetic field being magnetized. Alternatively, the coil that detects the strength of the magnetic field is affected by the magnetization of the sample to be measured, and the strength of the measured magnetic field does not match the magnetic field actually applied to the sample to be measured. Therefore, the magnetization of the sample to be measured cannot be measured with high accuracy, and the strength of the magnetic field applied to the sample to be measured cannot be measured with high accuracy.

The present invention has been made to solve the above-mentioned problems of the prior art, and can measure the magnetization of the sample to be measured with high accuracy, and can measure the strength of the magnetic field applied to the sample to be measured. It is an object of the present invention to provide a magnetization measuring method capable of measuring with high accuracy.

A brief description of typical inventions disclosed in the present application is as follows.

The magnetization measuring method as one aspect of the present invention is a magnetization measuring method for measuring the magnetization of a magnetic material. The magnetization measuring method includes a step (a) of holding a magnetic material by a holding portion on a first axis extending in the first direction, and a first direction of the magnetic material held by the holding portion in the first direction. It includes a step (b) in which a magnetic field is applied by an application unit. Further, in the magnetization measurement method, the magnetization of the magnetic material and the magnetization of the magnetic material when the step (c) is performed while the first magnetic field applied by the application unit is swept by the sweep unit, and the step (c) is performed. It includes a step (d) of measuring the strength of the first magnetic field by a measuring unit. The measuring unit includes a first coil that is wound around the first axis so as to surround the magnetic material held by the holding unit and generates a first induced electromotive force due to a change in the interlinking magnetic flux. It has a second coil that is wound around the first axis so as to surround the first coil and generates a second induced electromotive force by a change in the interlinking magnetic flux. Further, the measuring unit is wound around the first axis so as to surround the second coil, and the third coil that generates the third induced electromotive force by the change of the interlinking magnetic flux, and the first axis. It has a fourth coil that is wound around the third coil and generates a fourth induced electromotive force due to a change in the interlinking magnetic flux. Further, the measuring unit measures the magnetization of the magnetic material held in the holding unit based on the first difference value, which is the difference between the absolute value of the first induced electromotive force and the absolute value of the second induced electromotive force. It has a magnetization measuring unit and a magnetic field measuring unit that measures the strength of the first magnetic field based on the second difference value, which is the difference between the absolute value of the third induced electromotive force and the absolute value of the fourth induced electromotive force. .. The number of turns of the first coil and N _A, the number of turns of the second coil and N _B, the number of turns of the third coil and N _C, the number of turns of the fourth coil and N _D, the first coil first the area of the cross section perpendicular to the axis and _{S a,} when the area of the cross section perpendicular to the first axis of the second coil and the _{S B, (N a × S} a -N B × S B) / (N a × S _a absolute value of) is 0.02 or _less, 0.02 or less the absolute value of _{(N C -N D) / N} C. The first part of the first coil, the second part of the second coil, the third part of the third coil, and the fourth part of the fourth coil are arranged at the same position with each other in the first direction. Then, the first thickness of the first coil in the first direction, the second thickness of the second coil in the first direction, the third thickness of the third coil in the first direction, and the fourth coil in the first direction. The fourth thickness of each is less than 7 mm, or both are thinner than the fifth thickness of the magnetic material held in the holding portion in the first direction, and in the step (c), the first magnetic field is applied. , Step (b) is performed while sweeping in both the positive and negative directions by the sweeping portion.

By applying one aspect of the present invention, the magnetization of the sample to be measured can be measured with high accuracy in a magnetization measuring device for measuring the magnetization of the sample to be measured made of a magnetic material, and the sample is applied to the sample to be measured. The strength of the magnetic field can be measured with high accuracy.

It is a block diagram including a partial cross section which shows the whole structure of the magnetization measuring apparatus of embodiment. It is a figure which shows typically the part to be measured and the part arranged around it in the magnetization measuring apparatus of embodiment. It is a figure including a part cross section which shows typically the part arranged around the exciting coil in the magnetization measuring apparatus of a comparative example. It is a circuit diagram which shows an example of the structure of the exciting power source when the exciting coil applies a pulse magnetic field. It is a graph which shows typically the time dependence of the strength of the magnetic field applied to the sample to be measured when the exciting coil applies a pulse magnetic field. It is a graph which shows typically the magnetization hysteresis curve of the sample to be measured.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

It should be noted that the disclosure is merely an example, and those skilled in the art can easily conceive of appropriate changes while maintaining the gist of the invention are naturally included in the scope of the present invention. Further, in order to clarify the description, the drawings may schematically represent the width, thickness, shape, etc. of each part as compared with the embodiment, but this is merely an example, and the interpretation of the present invention is used. It is not limited.

Further, in the present specification and each figure, the same elements as those described above with respect to the above-mentioned figures may be designated by the same reference numerals, and detailed description thereof may be omitted as appropriate.

Further, in the drawings used in the embodiments, hatching (shading) attached to distinguish the structures may be omitted depending on the drawings.

In the following embodiments, when the range is indicated as A to B, A or more and B or less are indicated unless otherwise specified.

(Embodiment)
<Magnetization measuring device>
First, the magnetization measuring device of the embodiment which is one embodiment of the present invention will be described. The magnetization measuring device of the present embodiment is a magnetization measuring device for measuring the magnetization of a sample to be measured made of a magnetic material.

FIG. 1 is a block diagram including a partial cross section showing the overall configuration of the magnetization measuring device of the embodiment. FIG. 2 is a diagram schematically showing a sample to be measured and a portion arranged around the sample to be measured in the magnetization measuring device of the embodiment.

As shown in FIG. 1, the magnetization measuring device 11 of the present embodiment includes a holding unit 12, an applying unit 13, a sweeping unit 14, a measuring unit 15, and a control unit 16. The holding unit 12 holds the sample MS1 to be measured made of a magnetic material on the axis AX1 extending in the direction DR1 which is the vertical direction, for example. The application unit 13 applies the magnetic field MF1 in the direction DR1 to the sample MS1 to be measured held by the holding unit 12. The sweep unit 14 sweeps the magnetic field MF1 applied by the application unit 13. The measuring unit 15 measures the magnetization of the sample MS1 to be measured and the strength of the magnetic field MF1 when the magnetic field MF1 is applied to the sample MS1 to be measured by the applying unit 13 while sweeping the magnetic field MF1 by the sweeping unit 14. The control unit 16 controls the sweep by the sweep unit 14 and the measurement by the measurement unit 15. The details of the measuring unit 15 will be described later.

Preferably, the holding portion 12 provided in the magnetization measuring device 11 of the present embodiment has a cylindrical member 21 extending along the axis AX1, that is, in the direction DR1, and having a cylindrical shape, and a columnar shape. Each has a shape, and has an upper member 22 and a lower member 23 that sandwich the sample MS1 to be measured from above and below in the cylindrical member 21. Since the holding portion 12 has such a configuration, the sample MS1 to be measured can be held and fixed on the shaft AX1.

Further, it is more preferable that the tubular member 21 has a cylindrical shape, and it is more preferable that the upper member 22 and the lower member 23 have a cylindrical shape. Since the holding portion 12 has such a configuration, the sample MS1 to be measured having a cylindrical shape can be arranged on the axis AX1 in an axially symmetrical manner with the axis AX1 as the center.

Preferably, the application unit 13 has an exciting coil 31 that is wound around the shaft AX1 so as to surround the sample MS1 to be measured and has a cylindrical shape extending in the direction DR1. As a result, the magnetic field MF1 in the direction DR1 can be applied to the sample MS1 to be measured held in the holding unit 12.

Preferably, the sweep portion 14 is connected to the exciting coil 31, and the exciting coil 31 is operated by sweeping the exciting power supply 41 in which the current flows through the exciting coil 31 and the current flowing through the exciting coil 31 by the exciting power supply 41. It has a control panel 42 for sweeping the generated magnetic field.

Preferably, the measuring unit 15 has a coil 51, a coil 52, a coil 53, a coil 54, a magnetization measuring unit 55, and a magnetic field measuring unit 56. That is, the measuring unit 15 has four coils of coils 51, 52, 53 and 54. Although the details of the arrangement will be described later, the coils 51, 52, 53 and 54 are arranged concentrically around the shaft AX1 with the shaft AX1 as the center. Further, although the details of the operation will be described later, the magnetization measuring unit 55 measures the magnetization of the sample MS1 to be measured held in the holding unit 12 based on the induced electromotive force of each of the coils 51 and 52, and the magnetic field. The measuring unit 56 measures the strength of the magnetic field MF1 based on the induced electromotive force of each of the coils 53 and 54.

Preferably, the control unit 16 has a personal computer 61. The personal computer 61 is connected to the control panel 42. A calculation unit including, for example, a central processing unit (CPU) included in the personal computer 61 executes a program stored in a storage unit including, for example, a memory included in the personal computer 61, and controls the control panel 42. By controlling, the magnetic field generated by the exciting coil 31 is swept.

Next, the measuring unit 15 provided in the magnetization measuring device 11 of the present embodiment will be described while comparing with the measuring unit provided in the magnetization measuring device of the comparative example. FIG. 3 is a diagram including a partial cross section schematically showing an exciting coil and a portion arranged around the excitation coil in the magnetization measuring device of the comparative example.

As shown in FIG. 3, the magnetization measuring device 111 of the comparative example includes a measuring unit 115, and the measuring unit 115 includes a coil 151, a coil 152, a magnetization measuring unit 153, and a magnetic field measuring unit 154. .. That is, the measuring unit 115 has two coils, coils 151 and 152. Further, the magnetization measuring unit 153 is holding the sample MS1 to be measured held in the holding unit 12 based on a difference value which is a difference between the absolute value of the induced electromotive force of the coil 151 and the absolute value of the induced electromotive force of the coil 152. The magnetization of the magnetic field MF1 is measured by the magnetic field measuring unit 154 based on the induced electromotive force of the coil 152. The magnetization measuring device 111 of the comparative example also includes a holding unit 12 and an applying unit 13 as in the magnetization measuring device 11 of the embodiment.

In the magnetization measuring device 111 of the comparative example, the coil 151 is wound around the axis AX1 so as to surround the sample MS1 to be measured held by the holding portion 12, and the induced electromotive force is generated by the change of the interlinking magnetic flux. appear. However, like the coil 151, the coil 152 is wound around the shaft AX1 and generates an induced electromotive force due to a change in the interlinking magnetic flux, but unlike the coil 151, it is held by the holding portion 12. It is not wound around the sample MS1 to be measured. That is, the coil 151 and the coil 152 are arranged along the axis AX1, that is, in the direction DR1, at intervals from each other.

In the magnetization measuring device 111 of the comparative example, the magnetization measuring unit 153 is a difference between the absolute value of the induced electromotive force of the coil 151 and the absolute value of the induced electromotive force of the coil 152 when the magnetic field MF1 is applied while being swept. Based on the value, the magnetization of the sample MS1 to be measured held in the holding unit 12 is measured.

However, in the magnetization measuring device 111 of the comparative example, when the sample MS1 to be measured is made of, for example, a ferromagnetic metal which is a material of a permanent magnet, the electric resistance of the sample MS1 to be measured is small, so that when the magnetic field is swept and applied. The influence of the eddy current generated in the sample MS1 to be measured cannot be ignored. Therefore, there is a problem that the magnetization measured by the magnetization measuring unit 153 deviates from the true magnetization value of the sample MS1 to be measured.

Alternatively, when a yoke made of ferromagnetic metal cannot be provided around the sample MS1 to be measured, the magnetic circuit formed around the sample MS1 to be measured becomes a so-called open magnetic circuit, and is located around the sample MS1 to be measured. There is a problem that the influence of the demagnetism becomes large and the magnetization value measured by the magnetization measuring unit 153 deviates from the true magnetization value of the sample MS1 to be measured.

Alternatively, inside the exciting coil 31, the strength of the magnetic field tends to be non-uniform between different positions in the direction DR1. Therefore, when the coil 151 and the coil 152 are arranged at intervals in the direction DR1, the strength of the magnetic field measured by the coil 152 is the strength of the magnetic field MF1 actually applied to the sample MS1 to be measured. Does not match. Therefore, there is a problem that the magnetization value measured by the magnetization measuring unit 153 deviates from the magnetization value corresponding to the strength of the magnetic field measured by the magnetic field measuring unit 154.

Alternatively, a part of the magnetic flux generated by the magnetization of the sample MS1 to be measured interlinks with the coil 152, so that the strength of the magnetic field applied to the coil 152 does not match the strength of the magnetic field applied by the exciting coil 31. .. That is, the coil 152 is affected by the sample MS1 to be measured. Therefore, there is a problem that the magnetization value measured by the magnetization measuring unit 153 deviates from the magnetization value corresponding to the strength of the magnetic field measured by the magnetic field measuring unit 154.

In the magnetization measuring device 111 of the comparative example, since the coil 151 and the coil 152 are arranged at intervals in the direction DR1, the strength of the magnetic field measured by the coil 152 is actually applied to the sample MS1 to be measured. It does not match the strength of the magnetic field MF1. In such a case, the magnetization of the sample MS1 to be measured is the absolute value of the induced electromotive force of the coil 151 for measuring the magnetization and the absolute value of the induced electromotive force of the coil 152 for measuring the strength of the magnetic field. When measured based on the difference value, which is the difference from the value, the magnetization of the measured sample MS1 is more likely to deviate from the magnetization value corresponding to the strength of the magnetic field measured by the magnetic field measuring unit 154. Become.

On the other hand, as described above, in the magnetization measuring device 11 of the present embodiment, the measuring unit 15 has four coils of coils 51, 52, 53 and 54, and the coils 51, 52, 53 and 54 are shafts. Around AX1, they are arranged concentrically around the axis AX1.

The coil 51 is wound around the shaft AX1 so as to surround the sample MS1 to be measured held by the holding portion 12, and an induced electromotive force is generated by a change in the interlinking magnetic flux. The coil 52 is wound around the shaft AX1 so as to surround the coil 51, and an induced electromotive force is generated by a change in the interlinking magnetic flux. The coil 53 is wound around the shaft AX1 so as to surround the coil 52, and an induced electromotive force is generated by a change in the interlinking magnetic flux. The coil 54 is wound around the shaft AX1 so as to surround the coil 53, and an induced electromotive force is generated by a change in the interlinking magnetic flux.

The magnetization measuring unit 55 magnetizes the sample MS1 to be measured held in the holding unit 12 based on the difference value which is the difference between the absolute value of the induced electromotive force of the coil 51 and the absolute value of the induced electromotive force of the coil 52. To measure. The magnetic field measuring unit 56 measures the strength of the magnetic field MF1 based on the difference value which is the difference between the absolute value of the induced electromotive force of the coil 53 and the absolute value of the induced electromotive force of the coil 54.

For coils 51 and 52, the number of turns of the coil 51 and _{N A,} the number of turns of the coil 52 and _{N B,} and _{S A} the area of the cross section perpendicular to the axis AX1 of the coil 51, perpendicular to the axis AX1 of the coil 52 when the area of a cross section was _{S B,} the product of the area of the turns and the cross section of each coil 51 and 52, to satisfy the _{N a × S a = N B} × S B.

The area of the cross section perpendicular to the axis AX1 of the coil 51 is the area inside the circle formed by the center of the wire (winding) of the coil 51, or the inner end of the wire (winding) from the center of the coil 51 (the winding). It means the area of a circle whose radius is the sum of the distance to the side surface of the lead wire on the coil center side) and the radius of the lead wire (winding). The same applies to the coils 52, 53 and 54.

Further, _{N B} × _{S B} is may be no completely equal to the _{N A} × _{S A,} is _{N B} × _{S B} may be substantially equal to the _{N A} × _{S A.} Thus, it may be a _{(N A × S A -N B} × S B) / absolute value _{(N A} × _{S A)} is 0.02 or less (2% or less). Thus, it is possible to substantially equalize the _{N B} × _{S B} and _{N A} × _{S A. Alternatively, (N A × S A -N} B × S B) / (N B × S B) of the absolute value may be 0.02 or _{less, 2 × (N A × S} A -N B × S the absolute value of _{B) / (N a × S} a + N B × S B) may be 0.02 or less. The absolute value of 0.02 or less means that the absolute value is 0, or the absolute value is larger than 0 and 0.02 or less.

Moreover, the magnetic moment of the sample to be measured MS1 is M, the strength of the magnetic field MF1 and H, the magnetic flux density coil 51 is detected as B _A, when the magnetic flux density coil 52 detects a B _B, the magnetic flux density B _a and B _B is proportional to the sum of the magnetic moment M and the magnetic field H of the measured sample MS1, expressed by the following equation (equation 1).

Here, when the magnetic flux interlinking with the coil 51 is φ _A , the magnetic flux interlinking with the coil 52 is φ _B, and the area of the cross section perpendicular to the axis AX1 of the sample MS1 to be measured is S _S , the magnetic flux φ _A. Is expressed by the following formula (Equation 2), and the magnetic flux φ _B is expressed by the following formula (Equation 3).

The coil 51 and 52 when the induced voltage is induced electromotive force of the coils 51 and e _EN, the induced voltage is induced electromotive force of the coil 52 and e _JB, and connecting the coil 51 and the coil 52 in a counter-series When the induced voltage, which is the induced electromotive force of, is e _J , the induced voltage e _J is expressed by the following equation (Equation 4).

As shown in equation (Equation 4), when the _{N B} × _{S B} substantially equal to _{N A} × _{S A} is the induced voltage _{e J} is unaffected by the magnetic field H, the magnetic moment of the sample to be measured MS1 Only affected by M. Therefore, by integrating the induced voltage e _J time, it is possible to obtain a magnetic moment M. The magnetic moment M is expressed by the following mathematical formula (Equation 5).

Further, when the volume of the sample MS1 to be measured is V, the magnetization J can be obtained by dividing the magnetic moment M by the volume V of the sample MS1 to be measured. Magnetization J is expressed by the following mathematical formula (Equation 6).

On the other hand, as the coils 53 and 54, the number of turns of the coil 53 and _{N C,} when the number of turns of the coil 54 was set to _{N D,} the number of turns of each coil 53 and _54, meet N C = _{N D} To.

Also, may be without _{N D} is completely equal to the _{N C, N D} may be substantially equal to the _{N C. Therefore,} as long as the absolute value of _{(N C -N D) / N} C is 0.02 or less (2% or less). Thus, it is possible to substantially equalize the _{N D} and _{N C. Alternatively, (N C -N D) /} N absolute value of _D is may be 0.02 or less, the absolute value of the _{2 × (N C -N D)} / (N C + N D) is 0.02 or less It may be.

Further, the magnetic flux density coil 53 is detected as B _C, when the magnetic flux density coil 54 is detected and a B _D, the magnetic flux density B _C and B _D are the magnetic moment M and the magnetic field H of the measured sample MS1 Since it is proportional to the sum, it is expressed by the following formula (Equation 7).

Here, the _{S C} the area of the cross section perpendicular to the axis AX1 of the coil 53, and _{S D} of the area of the cross section perpendicular to the axis AX1 of the coil 54, the magnetic flux interlinking the coil 53 and phi _C, the coil 54 When the interlinking magnetic flux is φ _D , the magnetic flux φ _C is expressed by the following formula (Equation 8), and the magnetic flux φ _D is expressed by the following formula (Equation 9).

Further, the induced voltage is induced electromotive force of the coils 53 and e _HC, the induced voltage is induced electromotive force of the coils 54 and e _HD, coils 53 and 54 when connecting the coil 53 and the coil 54 in a counter-series When the induced voltage, which is the induced electromotive force of the above, is e _H , the induced voltage e _H is expressed by the following equation (Equation 10).

As shown in equation (Equation 10), if N _D is substantially equal to N _C is the induced voltage e _H is unaffected by the magnetic moment M of the measured sample MS1, only affected to a magnetic field H .. Therefore, the magnetic field H can be obtained by time-integrating the induced voltage e _H. The magnetic field H is represented by the following mathematical formula (Equation 11).

As shown in FIG. 2, in the magnetization measuring device 11 of the present embodiment, the partial PR1 of the coil 51, the partial PR2 of the coil 52, the partial PR3 of the coil 53, and the partial PR4 of the coil 54 are mutually arranged in the direction DR1. They are located at the same position PS1. As a result, the coils 51, 52, 53 and 54 can be arranged on the same plane PL1.

In the magnetization measuring device 11 of the present embodiment, the thickness TH1 of the coil 51 in the direction DR1, the thickness TH2 of the coil 52 in the direction DR1, the thickness TH3 of the coil 53 in the direction DR1, and the thickness of the coil 54 in the direction DR1. TH4 is thinner than the thickness THS in the direction DR1 of the sample MS1 to be measured, which is held by the holding portion 12 (see FIG. 1).

Here, consider the case where the thickness THS is 7 mm. This is the length of the test piece in the direction along the applied magnetic field, that is, the direction along the applied magnetic field MF1 in the permanent magnet measuring method using the pulsed magnetic field of the Japan Electronic Materials Industry Association standard EMAS-7007. This is because the length of the sample MS1 to be measured is 7 mm.

In such a case, the thickness TH1 of the coil 51, the thickness TH2 of the coil 52, the thickness TH3 of the coil 53, and the thickness TH4 of the coil 54 are all less than 7 mm. As a result, the thickness of each of the coils 51, 52, 53 and 54 is defined as 7 mm by the permanent magnet measurement method using the pulse magnetic field of the Japan Electronic Materials Industry Association standard EMAS-7007, that is, the test piece to be measured. The thickness of the sample MS1 in the direction DR1 can be made thinner than the thickness THS.

As described above, in the magnetization measuring device 11 of the present embodiment, the coils 51, 52, 53 and 54 having a thin thickness in the direction DR1 are used. As a result, the magnetic flux at the center position of the sample MS1 to be measured in the direction DR1 can be interlinked with the coils 51 and 52, and the magnetization of the sample MS1 to be measured is generated based on the induced voltage of each of the coils 51 and 52. It can be measured with high accuracy. Further, a magnetic field at the center position of the sample MS1 to be measured in the direction DR1 can be applied to the coils 53 and 54, and the magnetic field is applied to the sample MS1 to be measured based on the induced voltage of each of the coils 53 and 54. The strength of the magnetic field MF1 can be measured with high accuracy.

The eddy current flowing in the sample MS1 to be measured when the magnetic field is applied while sweeping is not the central portion in the direction DR1 of the sample MS1 to be measured, but both ends in the direction DR1 of the sample MS1 to be measured, that is, the sample MS1 to be measured. It flows to the upper end or the lower end. In the magnetization measuring device 111 of the comparative example described above, the thickness TH101 of the coil 151 in the direction DR1 is thicker than the thickness THS of the sample MS1 to be measured in the direction DR1. Therefore, the influence of the eddy current flowing in the upper end portion or the lower end portion of the sample MS1 to be measured on the induced electromotive force of the coil 151 becomes so large that it cannot be ignored.

On the other hand, in the magnetization measuring device 11 of the present embodiment, the thickness TH1 of the coil 51, the thickness TH2 of the coil 52, the thickness TH3 of the coil 53, and the thickness TH4 of the coil 54 are all covered in the direction DR1. The thickness of the measurement sample MS1 is thinner than the THS. Therefore, the induced voltage e _J which is the difference between the absolute value of the induced electromotive force of each coil 51 and 52, the smaller the influence of the eddy currents flowing in the upper portion or a lower end portion of the sample to be measured MS1 is negligible. Therefore, the value of magnetization measured by the magnetization measuring unit 55 can be brought close to the true value of magnetization of the sample MS1 to be measured.

Further, in the magnetization measuring device 11 of the present embodiment, the thicknesses TH1, TH2, TH3 and TH4 are all thinner than the thickness THS. Therefore, the thickness of the sample MS1 to be measured becomes relatively thick with respect to the thickness of the coil, and the influence of the demagnetic field around the sample MS1 to be measured becomes small. Therefore, the value of magnetization measured by the magnetization measuring unit 55 can be brought close to the true value of magnetization of the sample MS1 to be measured.

Further, in the magnetization measuring device 11 of the present embodiment, the coils 51, 52, 53 and 54 are arranged on the same plane PL1. As a result, the intensities of the magnetic fields applied to each of the coils 51, 52, 53 and 54 become equal to each other. Therefore, the value of magnetization measured by the magnetization measuring unit 55 can be brought close to the value of magnetization corresponding to the strength of the magnetic field measured by the magnetic field measuring unit 56.

Further, the magnetization measuring apparatus 11 of the present embodiment, by substantially equal to N _D and N _C, the induced voltage e _H coils 53 and 54 are not affected by the magnetic moment M of the measured sample MS1 , Affected only by the magnetic field H. Therefore, the strength of the magnetic field measured by the coils 53 and 54 becomes equal to the strength of the magnetic field MF1 actually applied to the sample MS1 to be measured. Therefore, the value of magnetization measured by the magnetization measuring unit 55 can be brought close to the value of magnetization corresponding to the strength of the magnetic field measured by the magnetic field measuring unit 56.

Further, in the magnetization measuring device 11 of the present embodiment, the magnetization of the sample MS1 to be measured is measured by the magnetization measuring unit 55, which is a circuit provided separately from the magnetic field measuring unit 56, which is a circuit for measuring the magnetic field. Therefore, the magnetization of the sample MS1 to be measured is based on the difference value which is the difference between the absolute value of the induced electromotive force of the coil for measuring the magnetization and the absolute value of the induced electromotive force of the coil for measuring the strength of the magnetic field. It is not measured. Therefore, the accuracy of the measured magnetization value can be improved.

That is, according to the magnetization measuring device 11 of the present embodiment, the magnetization of the sample MS1 to be measured can be measured with high accuracy by the magnetization measuring unit 55, and the strength of the magnetic field applied to the sample MS1 to be measured can be measured. The magnetic field measuring unit 56 can measure with high accuracy.

In the example shown in FIG. 1, the magnetization measuring unit 55 is provided between the coils 51 and 52 and the personal computer 61, and the magnetic field measuring unit 56 is provided between the coils 53 and 54 and the personal computer 61. .. However, the magnetization measuring unit 55 and the magnetic field measuring unit 56 may be included in the personal computer 61 included in the control unit 16.

Further, the coil 51 and the coil 52 have a difference value which is a difference between the absolute value of the induced electromotive force of the coil 51 and the absolute value of the induced electromotive force of the coil 52 when the magnetic field MF1 is swept by the sweep unit 14. May be connected in anti-series so that is output to the magnetization measuring unit 55. Alternatively, each of the induced electromotive force of the coil 51 and the induced electromotive force of the coil 52 is separately output to the magnetization measuring unit 55, and the magnetization measuring unit 55 determines the absolute value of the induced electromotive force of the coil 51 and the induced electromotive force of the coil 52. the difference between the absolute value of the power (the absolute value of the induced voltage e _J shown in the equation (equation 4)), may be calculated in the magnetization measuring unit 55.

Further, the coil 53 and the coil 54 have a difference value which is a difference between the absolute value of the induced electromotive force of the coil 53 and the absolute value of the induced electromotive force of the coil 54 when the magnetic field MF1 is swept by the sweep unit 14. May be connected in anti-series so that is output to the magnetic field measuring unit 56. Alternatively, each of the induced electromotive force of the coil 53 and the induced electromotive force of the coil 54 is separately output to the magnetic field measuring unit 56, and the magnetic field measuring unit 56 determines the absolute value of the induced electromotive force of the coil 53 and the induced electromotive force of the coil 54. the difference between the absolute value of the power (the absolute value of the induced voltage e _H shown in the equation (equation 10)), may be calculated in the magnetic field measuring unit 56.

Preferably, the personal computer 61 calculates the magnetization J of the sample MS1 to be measured based on the _{induced voltage e J} detected by the magnetization measuring unit 55, _{and based on the induced voltage e H} detected by the magnetic field measuring unit 56, the personal computer 61 calculates the magnetization J of the sample MS1 to be measured. The strength (magnetic field H) of the magnetic field MF1 applied to the sample MS1 to be measured is calculated, and the set data including the calculated magnetization J and the magnetic field H is stored in a storage unit such as a memory. Then, the personal computer 61 displays the magnetization hysteresis curve in a graph in which the magnetization J is represented on the vertical axis and the magnetic field H is represented on the horizontal axis based on a plurality of sets of data stored in the storage unit.

Preferably, each of the partial PR1 of the coil 51, the partial PR2 of the coil 52, the partial PR3 of the coil 53, and the partial PR4 of the coil 54 of the sample MS1 to be measured held by the holding portion 12 in the direction DR1. It is arranged at the same position as the center position CP1 in the direction DR1.

As a result, each of the coils 51, 52, 53 and 54 is far from both the upper end and the lower end of the sample MS1 to be measured in the direction DR1, so that the absolute value of the induced electromotive force of each of the coils 51 and 52 is the absolute value. of the induced voltage e _J is a difference, the influence of the eddy currents flowing in the upper portion or a lower end portion of the sample to be measured MS1 can be further reduced.

The center position in the direction DR1 of the coil 51 is the position CE1, the center position in the direction DR1 of the coil 52 is the position CE2, the center position in the direction DR1 of the coil 53 is the position CE3, and the center position in the direction DR1 of the coil 54 is the position CE4. And. In such a case, more preferably, each of the position CE1, the position CE2, the position CE3 and the position CE4 is arranged at the same position in the direction DR1 as the center position CP1 in the direction DR1 of the sample MS1 to be measured.

As a result, each of the coils 51, 52, 53 and 54 is farther from both the upper end and the lower end of the sample MS1 to be measured in the direction DR1, so that the absolute electromotive force of each of the coils 51 and 52 is absolute. the induced voltage e _J which is a difference value, can be reduced even more the influence of the eddy currents flowing in the upper portion or a lower end portion of the measured sample MS1.

In the direction DR1, the position CE1 does not have to be arranged at the same position as the center position CP1, and the distance in the direction DR1 between the position CE1 and the center position CP1 with respect to the thickness THS of the sample MS1 to be measured in the direction DR1. The ratio of may be 0.2 or less. Further, in the direction DR1, the position CE2 does not have to be arranged at the same position as the center position CP1, and the ratio of the distance in the direction DR1 between the position CE2 and the center position CP1 to the thickness THS is 0.2 or less. It should be. Further, in the direction DR1, the position CE3 does not have to be arranged at the same position as the center position CP1, and the ratio of the distance in the direction DR1 between the position CE3 and the center position CP1 to the thickness THS is 0.2 or less. It should be. Further, in the direction DR1, the position CE4 does not have to be arranged at the same position as the center position CP1, and the ratio of the distance in the direction DR1 between the position CE4 and the center position CP1 to the thickness THS is 0.2 or less. It should be.

Further, in the direction DR1, the position CE2 does not have to be arranged at the same position as the position CE1, and is between the position CE1 and the position CE2 with respect to the average value of the thickness TH1, the thickness TH2, or the thickness TH1 and TH2. The ratio of the distances in the direction DR1 of is 0.2 or less. Further, in the direction DR1, the position CE3 does not have to be arranged at the same position as the position CE1, and is between the position CE1 and the position CE3 with respect to the average value of the thickness TH1, the thickness TH3, or the thickness TH1 and TH3. The ratio of the distances in the direction DR1 of is 0.2 or less. Further, in the direction DR1, the position CE4 does not have to be arranged at the same position as the position CE1, and is between the position CE1 and the position CE4 with respect to the average value of the thickness TH1, the thickness TH4, or the thickness TH1 and TH4. The ratio of the distances in the direction DR1 of is 0.2 or less. Further, regarding the relationship between the position CE2 and the position CE3, the relationship between the position CE2 and the position CE4, and the relationship between the position CE3 and the position CE4, the relationship between the position CE1 and the position CE2 is also described above. , The relationship between position CE1 and position CE3, and the relationship between position CE1 and position CE4.

Preferably, the exciting coil 31 is wound around the shaft AX1 so as to surround the coil 54, and the coils 51, 52, 53 and 54 are surrounded by the central portion of the exciting coil 31 in the direction DR1.

In such a case, since the magnetic field MF1 applied to the sample MS1 to be measured and the coils 51, 52, 53 and 54 is parallel to the direction DR1, the influence of the magnetic field of the component intersecting the direction DR1 should be eliminated. The magnetization of the sample MS1 to be measured in a parallel magnetic field can be measured. Further, in the central portion of the excitation coil 31 in the direction DR1, the uniformity of the magnetic field strength between different positions in the direction DR1 is high (the variation is small), so that the position of the sample to be measured MS1 in the direction DR1 is the sample to be measured. The magnetization of the sample MS1 to be measured can be measured with high accuracy even when the MS1 is deviated from each other.

Preferably, the magnetization measuring device 11 includes an adjusting unit 17 that adjusts the position of the sample MS1 to be measured held in the holding unit 12 in the direction DR1. The adjusting unit 17 is the sample MS1 to be measured in which each of the partial PR1 of the coil 51, the partial PR2 of the coil 52, the partial PR3 of the coil 53, and the partial PR4 of the coil 54 is held by the holding portion 12 in the direction DR1. The position is adjusted so that it is arranged at the same position as the center position CP1 in the direction DR1.

As such an adjusting unit 17, for example, an adjusting unit 17 having a motor 71, a gear 72 connected to the motor 71, and a gear 73 meshed with the gear 72 and fixed to the lower member 23 is used. be able to. Thereby, for example, the lower member 23 can be moved along the axis AX1 in the same direction as or in the opposite direction to the direction DR1, and each of the coils 51, 52, 53 and 54 in the direction DR1 of the sample MS1 to be measured. It can be adjusted so that it is far from both the upper end and the lower end. Therefore, the induced voltage e _J which is the difference between the absolute value of the induced electromotive force of each coil 51 and 52, the influence of the eddy currents flowing in the upper portion or a lower end portion of the sample to be measured MS1 can be further reduced.

As described above, in the direction DR1, the position CE1 does not have to be arranged at the same position as the center position CP1, and between the position CE1 and the center position CP1 with respect to the thickness THS of the sample MS1 to be measured in the direction DR1. The ratio of the distances in the direction DR1 can be adjusted to be 0.2 or less. The position CE2, the position CE3, and the position CE4 are the same as those of the position CE1.

Further, as described above, in the direction DR1, the position CE2 does not have to be arranged at the same position as the position CE1, and the position CE1 and the average value of the thickness TH1, the thickness TH2, or the thickness TH1 and TH2 The ratio of the distance to the position CE2 in the direction DR1 can be adjusted to be 0.2 or less. Also, the relationship between position CE1 and position CE3, the relationship between position CE1 and position CE4, the relationship between position CE2 and position CE3, the relationship between position CE2 and position CE4, and position CE3. The relationship between the position CE4 and the position CE4 is the same as the relationship between the position CE1 and the position CE2.

Preferably, the exciting coil 31 is wound around the shaft AX1 so as to surround the coil 54, and a pulse magnetic field is applied to the sample MS1 to be measured. Further, the sweep unit 14 sweeps the magnetic field MF1 by passing a pulse current through the exciting coil 31. As a result, even when the sample to be measured is composed of a permanent magnet having a large saturation magnetization such as a neodymium iron boron (NdFeB) magnet, a magnetic field having sufficient strength to magnetically saturate the sample to be measured can be applied. Hereinafter, a case where the magnetization of the sample MS1 to be measured is measured when the exciting coil 31 applies a pulse magnetic field will be described. FIG. 4 is a circuit diagram showing an example of the configuration of an exciting power supply when the exciting coil applies a pulse magnetic field.

As shown in FIG. 4, the exciting power supply 41 included in the sweep unit 14 (see FIG. 1) includes a charging unit 43, a capacitor 44, and thyristors 45 and 46. One terminal of the charging unit 43 is connected to one terminal of the capacitor 44, the other terminal of the charging unit 43 is connected to the other terminal of the capacitor 44, and the charging unit 43 charges the capacitor 44. Further, one terminal of the capacitor 44 is connected to one terminal of the exciting coil 31 via thyristors 45 and 46 connected in antiparallel to each other, and the other terminal of the capacitor 44 is the other terminal of the exciting coil 31. It is connected to the terminal. The thyristors 45 and 46 are connected so that, for example, a current flows from one terminal of the capacitor 44 toward one terminal of the exciting coil 31 when the thyristor 45 is on, and one terminal of the exciting coil 31 when the thyristor 46 is on. It is connected so that a current flows from the capacitor 44 toward one terminal of the capacitor 44.

An arithmetic processing unit (not shown) included in the control panel 42 as the sweep unit 14 controls on / off of charging the capacitor 44 of the charging unit 43 and on / off of the thyristors 45 and 46. As a result, the exciting coil 31 can increase the strength of the magnetic field MF1 parallel to the direction DR1 and in the same direction (positive direction) as the direction DR1 from 0 to the maximum strength, and then decrease the strength from the maximum strength to 0. .. That is, the exciting coil 31 can apply a pulse magnetic field in the same direction (positive direction) as the direction DR1 and parallel to the direction DR1. Further, the exciting coil 31 can increase the strength of the magnetic field MF1 parallel to the direction DR1 and in the direction opposite to the direction DR1 (negative direction) from 0 to the maximum strength, and then decrease the strength from the maximum strength to 0. That is, the exciting coil 31 can apply a pulse magnetic field parallel to the direction DR1 and in the direction opposite to the direction DR1 (negative direction). As a result, the magnetization of the sample MS1 to be measured can be measured while sweeping the magnetic field applied to the sample MS1 to be measured by the exciting coil 31 in both the positive and negative directions.

The pulse width of the pulse magnetic field can be, for example, about 1 to 200 msec (milliseconds). Further, the pulse height (maximum intensity) of the pulse magnetic field can be set to, for example, about 100 to 10,000 kA / m.

When the exciting coil 31 applies a pulsed magnetic field, the absolute value of the induced electromotive force of each of the coils 51 and 52 is higher than when the exciting coil 31 applies a magnetic field at a sweeping speed smaller than the average sweeping speed of the pulsed magnetic field. the induced voltage e _J which is a difference, the influence of the eddy currents flowing in the upper portion or a lower end portion of the measured sample MS1 increases.

On the other hand, in the magnetization measuring device 11 of the present embodiment, the thickness TH1 of the coil 51, the thickness TH2 of the coil 52, the thickness TH3 of the coil 53, and the thickness TH4 of the coil 54 are all covered in the direction DR1. The thickness of the measurement sample MS1 is thinner than the THS. Therefore, it is possible to reduce the induced voltage e _J which is the difference between the absolute value of the induced electromotive force of each coil 51 and 52, the influence of the eddy currents flowing in the upper portion or a lower end portion of the measured sample MS1. Therefore, when the exciting coil 31 applies a pulsed magnetic field, the magnetization value measured by the magnetization measuring unit 55 is set as compared with the case where the exciting coil 31 applies the magnetic field at a sweeping speed smaller than the average sweeping speed of the pulsed magnetic field. The effect of approaching the true magnetization value of the sample MS1 to be measured becomes large.

It is only necessary that the induced electromotive force of each of the coils 51, 52, 53 and 54 can be measured when the sweep unit 14 sweeps the strength of the magnetic field applied to the sample MS1 to be measured by the exciting coil 31, so that the exciting coil 31 can be used. The applied magnetic field does not have to be a pulse magnetic field. A DC power supply is used as the exciting power supply 41, and the sweep unit 14 sweeps the current flowing through the exciting coil 31 so that the magnetic field generated by the exciting coil 31 gradually increases from 0 to the maximum strength, and then reaches the maximum. The strength may be gradually reduced to 0.

<Magnetization measurement method>
Next, the magnetization measuring method of the present embodiment will be described with reference to FIGS. 1 and 2. The magnetization measuring method of the present embodiment is a magnetization measuring method for measuring the magnetization of a sample to be measured made of a magnetic material.

In the magnetization measurement method of the present embodiment, the sample MS1 to be measured made of a magnetic material is held by the holding portion 12 on the axis AX1 extending in the direction DR1 (step S11). Then, the magnetic field MF1 in the direction DR1 is applied by the application unit 13 to the sample MS1 to be measured held in the holding unit 12 (step S12).

In the magnetization measurement method of the present embodiment, step S12 is performed while sweeping the magnetic field MF1 applied by the application unit 13 by the sweep unit 14 (step S13). Then, when performing step S13, the magnetization and magnetic field strength of the sample to be measured MS1 are measured by the measuring unit 15 (step S14).

As described above, the measuring unit 15 has four coils of coils 51, 52, 53 and 54, and the coils 51, 52, 53 and 54 are concentric around the shaft AX1 with the shaft AX1 as the center. It is arranged. Further, the measuring unit 15 includes a magnetization measuring unit 55 and a magnetic field measuring unit 56. The magnetization measuring unit 55 magnetizes the sample MS1 to be measured held in the holding unit 12 based on the difference value which is the difference between the absolute value of the induced electromotive force of the coil 51 and the absolute value of the induced electromotive force of the coil 52. To measure. The magnetic field measuring unit 56 measures the strength of the magnetic field MF1 based on the difference value which is the difference between the absolute value of the induced electromotive force of the coil 53 and the absolute value of the induced electromotive force of the coil 54.

Further, as described above, the thickness TH1 of the coil 51 in the direction DR1, the thickness TH2 of the coil 52 in the direction DR1, the thickness TH3 of the coil 53 in the direction DR1, and the thickness TH4 of the coil 54 in the direction DR1 are Both are less than 7 mm, or both are thinner than the thickness THS in the direction DR1 of the sample MS1 to be measured held in the holding portion 12.

According to the magnetization measuring method of the present embodiment as described above, the magnetization of the sample MS1 to be measured can be measured with high accuracy by the magnetization measuring unit 55, and the strength of the magnetic field MF1 applied to the sample MS1 to be measured can be measured. , The magnetic field measuring unit 56 can measure with high accuracy.

Preferably, in the magnetization measurement method of the present embodiment, the position of the sample MS1 to be measured held in the holding unit 12 in the direction DR1 is adjusted by the adjusting unit 17 (step S15). Then, in step S15, each of the partial PR1 of the coil 51, the partial PR2 of the coil 52, the partial PR3 of the coil 53, and the partial PR4 of the coil 54 is held by the holding portion 12 in the direction DR1. The position of the sample MS1 to be measured is adjusted by the adjusting unit 17 so that the sample MS1 to be measured is arranged at the same position as the center position CP1 in the direction DR1 of the MS1. As a result, each of the coils 51, 52, 53 and 54 is far from both the upper end and the lower end of the sample MS1 to be measured in the direction DR1, so that the absolute value of the induced electromotive force of each of the coils 51 and 52 is the absolute value. of the induced voltage e _J is a difference, it is possible to reduce the influence of the eddy currents flowing in the upper portion or a lower end portion of the measured sample MS1.

Next, a case where the excitation coil 31 measures the magnetization of the sample MS1 to be measured when the magnetic field MF1 as a pulse magnetic field is applied will be described. FIG. 5 is a graph schematically showing the time dependence of the strength of the magnetic field applied to the sample to be measured when the exciting coil applies a pulsed magnetic field. FIG. 6 is a graph schematically showing the magnetization hysteresis curve of the sample to be measured.

When the sweeping unit 14 has the exciting power supply 41 shown in FIG. 4, as described above, the magnetic field applied to the sample to be measured MS1 by the exciting coil 31 is swept in both the positive and negative directions, and the sample to be measured is swept. The magnetization of MS1 can be measured. Therefore, as shown in FIG. 5, a pulse magnetic field having sufficient strength is first applied in the same direction (positive direction) as the direction DR1 (see the waveform WF1 in FIG. 5) until the magnetization of the sample MS1 to be measured is saturated. The magnetization-magnetic field curve (JH curve) is measured while magnetizing the measurement sample MS1. At this time, the magnetic field MF1 is applied by the exciting coil 31 while the magnetic field MF1 is swept by the sweeping portion 14 by passing a pulse current through the exciting coil 31.

Next, a pulse magnetic field having the same intensity is applied in the direction opposite to the direction DR1 (negative direction) (see the waveform WF2 in FIG. 5), and J while magnetizing the sample MS1 to be measured until the magnetization of the sample MS1 to be measured is saturated. -Measure the H curve. Next, a pulse magnetic field having the same intensity is applied again in the same direction (positive direction) as the direction DR1 (see the waveform WF3 in FIG. 5), and the sample MS1 to be measured is magnetized until the magnetization of the sample MS1 to be measured is saturated. Measure the JH curve.

After that, with the sample MS1 to be measured taken out, the JH curve is applied in the same direction as the direction DR1 (positive direction) and in the direction opposite to the direction DR1 (negative direction) while applying pulse magnetic fields having the same intensity. (See waveforms WF4 and WF5 in FIG. 5). Then, the JH curve obtained by subtracting the JH curve for the waveform WF5 from the JH curve for the waveform WF2 is shown in the graph in which the magnetization J is represented on the vertical axis and the magnetic field H is represented on the horizontal axis. The JH curve, which is represented by the 2nd quadrant and the 3rd quadrant and is obtained by subtracting the JH curve of the waveform WF4 from the JH curve of the waveform WF3, is divided into the 4th quadrant and the 1st quadrant of the same graph. show. As a result, as shown in FIG. 6, the magnetization hysteresis curve of the sample MS1 to be measured can be obtained.

Further, the magnetization hysteresis curve shown in FIG. 6, the residual magnetization _{J r} of the measured sample MS1, and can determine the coercivity _{H cJ.} Remanence J _r is represented in the first quadrant, and, the value of magnetization corresponding to H = 0 of the curve, i.e. J-H demagnetization curve in reducing the magnetic field H, the coercivity H _cJ can It is a value of the strength of the magnetic field represented in the second quadrant and corresponding to J = 0 of the curve when the magnetic field H is reduced, that is, the JH demagnetization curve. _{Further, since the residual magnetization Jr} and the residual magnetic flux density _Br are substantially equal to each other due to the relationship of B = J + μ ₀ H, the residual magnetic flux density _Br can be calculated _{from the residual magnetization Jr.}

Hereinafter, the present embodiment will be described in more detail based on the examples. The present invention is not limited to the following examples.

As the magnetization measuring device of the example, the magnetization measuring device 11 shown in FIGS. 1 and 2 was prepared. The magnetization measuring device 11 of the embodiment includes an exciting coil 31 having 350 turns and coils 51, 52, 53 and 54. In the magnetization measuring device 11 of such an embodiment, the magnetic flux density at the center position CP1 of the exciting coil 31 in the direction DR1 and the magnetic flux densities of the coils 51, 52, 53 and 54 when the current flowing through the exciting coil 31 is 4250 A. The average magnetic flux density inside each was calculated. The results are shown in Table 1. In Table 1, the center position CP1 of the exciting coil 31 in the direction DR1 is referred to as “exciting coil center”, and the coils 51, 52, 53, 54 are referred to as J coil inside, J coil outside, H coil inside, and H. It is written as the outside of the coil.

As shown in Table 1, the difference between the magnetic flux density at the center position CP1 of the exciting coil 31 in the direction DR1 and the average magnetic flux density inside each of the coils 51, 52, 53 and 54 is 0.075% or less. rice field. Therefore, the intensities of the magnetic field at the center position CP1 of the exciting coil 31 and the magnetic fields applied to the insides of the coils 51, 52, 53 and 54 can be considered to be the same.

Next, when a neodymium iron boron (NdFeB) bonded magnet and an NdFeB sintered magnet having a diameter of 10 mm and a thickness of 7 mm are used as the sample MS1 to be measured, the magnetization hysteresis curve is repeatedly measured 20 times to obtain the result. from the magnetization hysteresis curves that are to determine the residual flux density B _r and coercivity H _cJ. As a result, in the case of using NdFeB bonded magnets as the measured sample MS1, repeatability of remanence _{B r} is 0.38% ±, repeatability of coercivity _{H cJ} is 0.19% ±, Both were small values. In the case of using the NdFeB sintered magnet as the measured sample MS1, repeatability of remanence _{B r} is 0.30% ±, repeatability of coercivity _{H cJ} is 0.20% ±, Both were small values.

Although the invention made by the present inventor has been specifically described above based on the embodiment thereof, the present invention is not limited to the embodiment and can be variously modified without departing from the gist thereof. Needless to say.

Within the scope of the idea of the present invention, those skilled in the art can come up with various modified examples and modified examples, and it is understood that these modified examples and modified examples also belong to the scope of the present invention.

For example, a person skilled in the art appropriately adds, deletes, or changes the design of each of the above-described embodiments, or adds, omits, or changes the conditions of the process of the present invention. As long as it has a gist, it is included in the scope of the present invention.

11 Magnetization measuring device 12 Holding unit 13 Applying unit 14 Sweeping unit 15 Measuring unit 16 Control unit 17 Adjusting unit 21 Cylindrical member 22 Upper member 23 Lower member 31 Exciting coil 41 Exciting power supply 42 Control panel 43 Charging unit 44 Condenser 45, 46 Cylister 51-54 Coil 55 Magnetization measurement unit 56 Magnetic field measurement unit 61 Personal computer 71 Motor 72, 73 Gear AX1 Axis CE1 to CE4, PS1 Position CP1 Center position DR1 Direction MF1 Magnetic field MS1 Measured sample PL1 Plane PR1 to PR4 Part WF1 to WF5 Waveform

Claims (7)

In the magnetization measurement method for measuring the magnetization of a magnetic material,
(A) A step of holding the magnetic material by a holding portion on a first axis extending in the first direction.
(B) A step of applying a first magnetic field in the first direction to the magnetic material held by the holding portion by the applying portion.
(C) A step of performing the step (b) while sweeping the first magnetic field applied by the application unit by the sweep unit.
(D) A step of measuring the magnetization of the magnetic material and the strength of the first magnetic field by a measuring unit when performing the step (c).
With
The measuring unit
A first coil that is wound around the first axis so as to surround the magnetic material held by the holding portion and generates a first induced electromotive force by a change in magnetic flux interlinking with the first coil.
A second coil that is wound around the first axis so as to surround the first coil and generates a second induced electromotive force due to a change in the interlinking magnetic flux.
A third coil that is wound around the first axis so as to surround the second coil and generates a third induced electromotive force due to a change in the interlinking magnetic flux.
A fourth coil that is wound around the first axis so as to surround the third coil and generates a fourth induced electromotive force due to a change in the interlinking magnetic flux.
Magnetization measurement for measuring the magnetization of the magnetic material held in the holding portion based on the first difference value which is the difference between the absolute value of the first induced electromotive force and the absolute value of the second induced electromotive force. Department and
A magnetic field measuring unit that measures the strength of the first magnetic field based on the second difference value, which is the difference between the absolute value of the third induced electromotive force and the absolute value of the fourth induced electromotive force.
Have,
The number of turns of the first coil and N _A, the number of turns of the second coil and N _B, the number of turns of the third coil and N _C, the number of windings of the fourth coil and N _D, the first and S _a the area of the cross section perpendicular to the first axis of first coil, when the area of the cross section perpendicular to the first axis of the second coil and the S _B,
The absolute value of _{(N A × S A -N B} × S B) / (N A × S A) is 0.02 or less,
The absolute value of _{(N C -N D) / N} C is 0.02 or less,
The first part of the first coil, the second part of the second coil, the third part of the third coil, and the fourth part of the fourth coil are arranged at the same positions in the first direction. Being done
The first thickness of the first coil in the first direction, the second thickness of the second coil in the first direction, the third thickness of the third coil in the first direction, and the first thickness. The fourth thickness of the fourth coil in the direction is less than 7 mm in each case .
In the step (c), a magnetization measuring method in which the first magnetic field is swept in both positive and negative directions by the sweeping portion, and the step (b) is performed. In the magnetization measurement method for measuring the magnetization of a magnetic material,
(A) A step of holding the magnetic material by a holding portion on a first axis extending in the first direction.
(B) A step of applying a first magnetic field in the first direction to the magnetic material held by the holding portion by the applying portion.
(C) A step of performing the step (b) while sweeping the first magnetic field applied by the application unit by the sweep unit.
(D) A step of measuring the magnetization of the magnetic material and the strength of the first magnetic field by a measuring unit when performing the step (c).
With
The measuring unit
A first coil that is wound around the first axis so as to surround the magnetic material held by the holding portion and generates a first induced electromotive force by a change in magnetic flux interlinking with the first coil.
A second coil that is wound around the first axis so as to surround the first coil and generates a second induced electromotive force due to a change in the interlinking magnetic flux.
A third coil that is wound around the first axis so as to surround the second coil and generates a third induced electromotive force due to a change in the interlinking magnetic flux.
A fourth coil that is wound around the first axis so as to surround the third coil and generates a fourth induced electromotive force due to a change in the interlinking magnetic flux.
Magnetization measurement for measuring the magnetization of the magnetic material held in the holding portion based on the first difference value which is the difference between the absolute value of the first induced electromotive force and the absolute value of the second induced electromotive force. Department and
A magnetic field measuring unit that measures the strength of the first magnetic field based on the second difference value, which is the difference between the absolute value of the third induced electromotive force and the absolute value of the fourth induced electromotive force.
Have,
The number of turns of the first coil and N _A, the number of turns of the second coil and N _B, the number of turns of the third coil and N _C, the number of windings of the fourth coil and N _D, the first and S _a the area of the cross section perpendicular to the first axis of first coil, when the area of the cross section perpendicular to the first axis of the second coil and the S _B,
The absolute value of _{(N A × S A -N B} × S B) / (N A × S A) is 0.02 or less,
The absolute value of _{(N C -N D) / N} C is 0.02 or less,
The first part of the first coil, the second part of the second coil, the third part of the third coil, and the fourth part of the fourth coil are arranged at the same positions in the first direction. Being done
The first thickness of the first coil in the first direction, the second thickness of the second coil in the first direction, the third thickness of the third coil in the first direction, and the first thickness. The fourth thickness of the fourth coil in the direction is thinner than the fifth thickness of the magnetic material held in the holding portion in the first direction.
In the step (c), a magnetization measuring method in which the first magnetic field is swept in both positive and negative directions by the sweeping portion, and the step (b) is performed. In the magnetization measuring method according to claim 2,
The center position of the first coil in the first direction is the first position, the center position of the second coil in the first direction is the second position, and the center position of the third coil in the first direction is the first position. The third position is set, the center position of the fourth coil in the first direction is set to the fourth position, the center position of the magnetic material held by the holding portion in the first direction is set to the fifth position, and the first position is set. The distance between the position and the fifth position in the first direction is defined as the first distance, and the distance between the second position and the fifth position in the first direction is defined as the second distance. When the distance between the position and the fifth position in the first direction is defined as the third distance, and the distance between the fourth position and the fifth position in the first direction is defined as the fourth distance.
The ratio of the first distance to the fifth thickness is 0.2 or less.
The ratio of the second distance to the fifth thickness is 0.2 or less.
The ratio of the third distance to the fifth thickness is 0.2 or less.
The method for measuring magnetization, wherein the ratio of the fourth distance to the fifth thickness is 0.2 or less. In the magnetization measuring method according to claim 3,
(E) A step of adjusting the fifth position by the adjusting unit,
A magnetization measurement method. In the magnetization measuring method according to any one of claims 1 to 4,
In the step (d), the JH curve is measured by the measurement of the measuring unit, and the JH curve is measured.
(F) With the magnetic material taken out, the first magnetic field is applied while being swept in both the positive and negative directions by the sweeping unit, and the JH curve is measured by the measuring unit.
(G) A step of obtaining a JH curve obtained by subtracting the JH curve measured in the step (f) from the JH curve measured in the step (d).
A magnetization measurement method. In the magnetization measuring method according to any one of claims 1 to 5,
In step (b), the application portion has a fifth coil that is wound around the first axis so as to surround the fourth coil and has a cylindrical shape extending in the first direction. , The first magnetic field is applied,
A method for measuring magnetization, wherein the first coil, the second coil, the third coil, and the fourth coil are surrounded by a central portion of the fifth coil in the first direction. In the magnetization measuring method according to any one of claims 1 to 5,
In the step (b), a sixth coil is wound around the first axis so as to surround the fourth coil, and the first magnetic field as a pulse magnetic field is applied to the magnetic material. The first magnetic field is applied by the application unit, and the first magnetic field is applied.
In the step (c), a magnetization measuring method is performed in which the step (b) is performed while the first magnetic field is swept by the sweeping portion by passing a pulse current through the sweeping portion through the sixth coil.

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