JP3127239B2 - Method and apparatus for magnetizing a metal magnet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for magnetizing a metal magnet such as a rare earth magnet used for a VCM (voice coil motor) or the like.

[0002]

2. Description of the Related Art In a hard disk device as an external storage device of an electronic computer, a VCM is used for mechanically driving a magnetic head, and a permanent magnet for the VCM which is magnetized in two poles on one side is required. Have been.

[0003] A conventional one-sided two-pole magnetizing method will be described with reference to FIGS. 9 and 10. In these figures, a first magnetized coil 1A is obtained by winding a winding 3A of a conducting wire several turns around a yoke 2A on which a silicon steel plate is laminated. Similarly, the second magnetized coil 1B is A winding 3B of a conductive wire is wound several turns around a yoke 2B on which silicon steel sheets are stacked. Then, the first and second magnetized coils 1A, 1
A plate-shaped metal magnet material 4A having a predetermined thickness is placed on B, and a similar magnetizing coil is provided above the metal magnet material 4A as necessary. Lumber 4
A is magnetized. In this case, as shown by arrows J and K in FIG. 10, the directions of the currents for winding the first magnetizing coil 1A and the second magnetizing coil 1B are reversed (for example, arrows L and K in FIG. 9). By generating a magnetic flux in the direction of M, magnetic poles of opposite polarities can be formed on one side of the metal magnet material 4A.

Under the condition that the current flowing through the magnetized coils 1A and 1B is extremely large, the yokes 2A and 2
Since B is magnetically saturated, an air-core magnetized coil omitting the yoke may be employed.

FIG. 11 shows one side 2 obtained by a conventional magnetizing method.
This is an example of the pole magnetized metal magnet 4, and the boundary region between the N pole and the S pole is a relatively wide neutral zone NZ.

FIG. 12 shows a magnetization waveform when a magnetized coil having a yoke made of a silicon steel plate is used. The magnetic flux density in a region opposed to the first magnetized coil 1A has a positive polarity, and Although the magnetic flux density in the region facing the magnetic coil 1B has a negative polarity, a small peak of the magnetic flux density also appears in the neutral zone NZ, and the magnetic field is disturbed.

FIG. 13 shows a magnetized waveform when an air-core magnetized coil without a yoke is used, and a small peak of the magnetic flux density also appears in the neutral zone NZ.

Such a disturbance of the magnetic field in the neutral zone NZ does not occur when the ferrite magnet material is magnetized, but when the metal magnet material 4A such as a rare earth magnet having a higher conductivity than ferrite is magnetized. Therefore, it is recognized that the eddy current flows through the metal magnet material 4A.

[0009]

Meanwhile, in the case of a single-sided, two-pole magnetized metal magnet for a VCM, it is required that the neutral zone is as narrow as possible and that the magnetic field in the neutral zone is not disturbed. However, according to the conventional magnetizing method described with reference to FIGS. 9 and 10, not only the width of the neutral zone is wide, but also as shown in FIGS. 12 and 13, the magnetic field of the neutral zone is disturbed.
At present, it cannot be used for VCM. For this reason, at the moment, two metal magnets having one pole on one side are combined and used for VCM.
There is a need for a step of joining two pieces, which increases the cost, and there is also a problem of reliability of joining.

Further, even when a single-sided, multi-pole magnetized metal magnet is used for applications other than VCM, disturbance of the magnetic field in the neutral zone is not preferable.

In view of the above, it is an object of the present invention to provide a method and an apparatus for magnetizing a metal magnet capable of narrowing a neutral zone and eliminating disturbance of a magnetic field in the neutral zone.

[0012]

In order to achieve the above object, a method of magnetizing a metal magnet according to the present invention comprises the steps of:
The first magnetized coil and the
2 and the first and second magnetized coils.
The center conductor is placed at the middle position of the magnetized coil of
Currents wound around the first and second magnetized coils in mutually opposite directions
And the first and second magnetizations
How the current flows through the windings adjacent to each other in the coil
A current in the same direction as the current flowing through the central conductor.
You.

[0013]

According to the present invention, there is provided a magnetizing apparatus for a metal magnet, comprising: a first magnetizing coil for forming a first magnetic pole on one side of a metal magnet material; and a second magnetizing coil having a polarity opposite to the first magnetic pole. A second magnetized coil for forming a magnetic pole, and a central conductor at a position intermediate between the winding portions of the first and second magnetized coils adjacent to each other and at a position close to the metal magnet material. It is provided with a configuration.

According to the present invention, the influence of the eddy current flowing through the metal magnet material during magnetization can be offset by the current flowing through the central conductor, and as a result, a single-sided multi-pole magnetized metal magnet can be obtained. Can be narrowed, and disturbance of the magnetic field in the neutral zone can be eliminated.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a method and apparatus for magnetizing a metal magnet according to the present invention will be described below with reference to the drawings.

A magnetizing device used in the embodiment of the present invention will be described with reference to FIGS. In these figures, the first
The magnetizing coil 1A is formed by winding a winding 3A of a conductive wire several turns around a yoke 2A having a rectangular cross section in which a silicon steel plate is laminated. Similarly, the second magnetizing coil 1B is formed by laminating a silicon steel plate. A winding 3B of a conductive wire is wound several turns around a yoke 2B having a rectangular cross section. Then, as shown in FIG. 2, a straight line parallel to the straight portions 11A and 11B, which are winding portions of the first and second magnetized coils 1A and 1B, which are approximately the same height as the end surfaces of the yokes 2A and 2B. A central conductor 10 is disposed at an intermediate position between the two yokes. Here, the central conductor 10 is provided for flowing a current in a direction to cancel the influence of the eddy current generated in the metal magnet material to be magnetized. Usually, the center conductor 10 is electrically connected in series to one of the windings 3A and 3B so that it can be energized by the same power supply.

In order to magnetize a flat metal magnet material 4A such as a rare earth magnet, the first and second magnetized coils 1A as shown in FIG.
A, a flat metal magnet material 4A having a predetermined thickness on 1B
2, the winding 3A of the first magnetized coil 1A has, for example, the direction of arrow J as shown in FIG. 2, and the winding 3B of the second magnetized coil 1B has an arrow K wound in the opposite direction. A current in the same direction (arrow P) as the direction of current flow in the linear portions 11A and 11B of each winding is applied to the straight central conductor 10 while a current having the same direction is supplied. As a result, the magnetized coil 1
A and 1B can generate magnetic fluxes in the directions of arrows L and M in FIG. 4 to form magnetic poles of opposite polarities on one side of the metal magnet material 4A, and generate eddy currents generated in the metal magnet material 4A. Can be offset by the current in the direction of arrow P flowing through the central conductor 10. If necessary, a magnetic body 12 may be disposed on the upper surface of the metal magnet material 4A as shown by the phantom line in FIG.

FIG. 5 shows the magnetized waveforms of the magnetized device with the yoke shown in FIGS. However, the current value applied to the first and second magnetized coils 1A and 1B and the current value applied to the central conductor 10 are set to be equal, and the currents of the straight portions 11A and 11B of each winding on both sides of the central conductor 10 are set. This is a case where the traveling direction and the current direction of the central conductor 10 are the same. From this figure, the magnetic flux density in the area facing the first magnetizing coil 1A has a positive polarity, and the magnetic flux density in the area facing the second magnetizing coil 1B has a negative polarity.
It can be seen that the width of Z is extremely narrow, and there is no disturbance in the magnetic flux density in the neutral zone NZ.

The first and second magnetized coils 1A, 1
When a current value of し た of the current value applied to B is applied to the central conductor 10, the influence of the eddy current in the metal magnet material cannot be completely eliminated, and disturbance of the magnetic field occurs in the neutral zone. It turns out that some will remain.

When the magnetizing operation is performed as shown in FIG. 4 using the magnetizing apparatus shown in FIGS. 1 to 3, as shown in FIG. 6, an N pole and an S pole are provided on one side and the width W of the neutral zone NZ is reduced. A metal magnet 4 having an extremely narrow width of 1 mm or less and having no magnetic field disturbance in the neutral zone can be obtained. in this way,
If the width of the neutral zone NZ is small and the magnetic field is not disturbed, the metal magnet can be sufficiently used as a permanent magnet for a VCM.

Under the condition that the current flowing through the magnetizing coils 1A and 1B is extremely large, the yokes 2A and 2
Since B is magnetically saturated, an air-core magnetized coil omitting the yoke may be employed. However, even in this case, the winding 3
The positional relationship between A and 3B and the central conductor 10 may be substantially the same.

FIG. 7 shows a magnetized waveform when the yoke is omitted from the magnetizing device shown in FIGS. 1 to 3 to form an air-core structure. However,
The current value applied to the first and second magnetized coils 1A and 1B and the current value applied to the central conductor 10 are set to be equal, and the current advancing direction of the straight portions 11A and 11B of each winding on both sides of the central conductor 10 is set. And the current direction of the central conductor 10 is the same. The magnetic flux density in the area facing the first magnetizing coil 1A has a positive polarity, and the magnetic flux density in the area facing the second magnetizing coil 1B has a negative polarity, and the width of the neutral zone NZ is also extremely narrow. Further, it can be seen that there is no disturbance in the magnetic flux density in the neutral zone NZ. Further, when each magnetized coil has an air-core structure, disturbance of magnetic flux density due to eddy current of the yoke is eliminated. As a result,
Even with a combination of air-core magnetized coil and central conductor,
One side has an N pole and an S pole, and the width of the neutral zone NZ is 1 mm or less, which is an extremely narrow width, so that a metal magnet free from disturbance of the magnetic field in the neutral zone can be obtained.

FIG. 8 shows another embodiment of the present invention. In this case, a magnetizing device having the first and second magnetizing coils 1A and 1B and the straight central conductor 10 shown in FIGS. 1 to 3 is arranged on one side of the metal magnet material 4A to be magnetized, A magnetizing device having third and fourth magnetizing coils 1C and 1D and a linear central conductor 10A is arranged on the other side, and magnetizing is performed by energizing both magnetizing devices simultaneously. However, the first magnetized coil 1
A is passed through the third magnetized coil 1C, which is opposite to the first magnetized coil 1A in the same direction as the first magnetized coil 1A, and the metal magnet is passed through the second magnetized coil 1B. Material 4A
A current in the direction of winding in the same direction as the second magnetized coil 1B is passed through the fourth magnetized coil 1D opposed to the second magnetized coil 1B, and a current in the same direction as the central wire 10 is also passed through the central conductor 10A. In this case, the current values of the central conductors 10 and 10A are set such that the sum of the currents flowing through the central conductors 10 and 10A cancels the eddy current flowing through the metal magnet material 4A.

In the case of FIG. 8 as well, each magnetizing coil may have an air-core structure, and if a sufficient current can be supplied to one central conductor 10 to cancel the eddy current, the other central conductor is used. 10A may be omitted.

In the above embodiments, the magnetized coil and the central conductor have a circular cross section, but the present invention is also effective for a rectangular cross section. The present invention is also applicable to a case where three or more magnetic poles are magnetized on one side.

[0027]

As described above, according to the present invention,
In addition to a first magnetized coil for forming a first magnetic pole on one surface of a metal magnet material and a second magnetized coil for forming a second magnetic pole having a polarity opposite to the first magnetic pole, A central conductor is disposed at an intermediate position between the winding portions of the first and second magnetized coils which are close to each other and at a position close to the metal magnet material, and an eddy current in the metal magnet material is provided at the central conductor. By passing a current for canceling the magnetic field, it is possible to obtain a single-sided multi-pole magnetized metal magnet having a very narrow neutral zone between adjacent magnetic poles of 1 mm or less.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a method and an apparatus for magnetizing a metal magnet according to the present invention, showing a magnetizing apparatus.

FIG. 2 is a plan view of the same.

FIG. 3 is a front view of the same.

FIG. 4 is a front view for explaining a magnetizing method using the magnetizing device shown in FIGS. 1 to 3;

FIG. 5 is a waveform chart showing an example of a magnetization waveform of the magnetization device (with yoke) of FIGS. 1 to 3;

FIG. 6 is a plan view showing an example of a single-sided, multi-pole magnetized metal magnet obtained by the present invention.

FIG. 7 is a waveform diagram showing an example of a magnetization waveform of the magnetization device (air core structure without yoke) of FIGS. 1 to 3;

FIG. 8 is a front view for explaining another magnetizing method according to the embodiment of the present invention.

FIG. 9 is a front view showing a conventional magnetizing method and apparatus.

FIG. 10 is a plan view of the same.

FIG. 11 is a plan view showing an example of a single-sided, multi-pole magnetized metal magnet obtained by a conventional magnetizing method.

FIG. 12 is a waveform chart showing an example of a magnetization waveform of a conventional magnetization device (with a yoke).

FIG. 13 is a waveform diagram showing an example of a magnetization waveform of a conventional magnetization device (air-core structure without a yoke).

[Explanation of symbols]

 1A, 1B, 1C, 1D Magnetizing coil 2A, 2B Yoke 3A, 3B Winding 4 Metal magnet 4A Metal magnet material 10, 10A Straight central conductor NZ neutral zone

Continuation of the front page (56) References JP-A-61-76242 (JP, A) JP-A-58-98904 (JP, A) JP-A-4-12505 (JP, A) JP-A-54-69794 (JP) , A) Fully open 60-48206 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01F 7/02 H01F 13/00

Claims (5)

(57) [Claims] A first magnetizing coil and a second magnetizing coil are disposed so as to be close to and opposed to one surface of a metal magnet material, and a center is provided at an intermediate position between the first and second magnetizing coils. A conductor is disposed, and currents are wound around the first and second magnetized coils in mutually opposite directions, respectively.
A method for magnetizing a metal magnet, characterized in that a current having the same direction as a traveling direction of a current flowing through winding portions of the first and second magnetized coils which are close to each other is supplied to the central conductor. 2. A method of magnetizing metal magnet of claim 1, wherein the magnetic material on the other surface of the metal magnetic material is disposed. 3. The first surface on the other surface of the metal magnet material.
And the third and fourth magnetizing coils disposed respectively facing the second magnetizing coil, claim 1 energizing current winding in the same direction as said first and second magnetizing coils respectively
The method for magnetizing a metal magnet as described above. 4. A current flowing through a winding portion adjacent to the third and fourth magnetized coils, wherein another central conductor is disposed at an intermediate position between the third and fourth magnetized coils. 4. The method according to claim 3 , wherein a current having the same direction as the traveling direction of the current is supplied to the other central conductor. 5. A first magnetized coil for forming a first magnetic pole on one surface of a metal magnet material, and a second magnetized coil for forming a second magnetic pole having a polarity opposite to the first magnetic pole. A magnetic coil,
A metal magnet magnetizing device, comprising: a center conductor located at an intermediate position between winding portions of the first and second magnetized coils adjacent to each other and at a position close to the metal magnet material.