JP3175797B2 - Multi-pole magnetization method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multipolar magnetizing method used to obtain a multipolar magnetized permanent magnet.

[0002]

2. Description of the Related Art There are many types of permanent magnets, such as ferrite magnets, alnico magnets, rare earth magnets, and most of them are anisotropic magnets.
Rare earth bonded magnets are also used as isotropic magnets. In recent years, Nd-Fe-B based rare earth bonded magnets have recently been widely used as isotropic magnets.

[0003] Among permanent magnets used for small motors, there are many permanent magnets in which a ring-shaped magnet material is multipolar magnetized on its inner or outer peripheral side. In many cases, a flat ring-shaped magnet material is multipolar magnetized on one side.

Such a multipolar magnetized permanent magnet is used for, for example, a spindle motor (brushless motor) used for driving an HDD, a brushless motor used for driving a tape such as a VTR, a paper feeder in a printer or a facsimile, and the like. It is used as a component of a PM type stepping motor to be used, and each is magnetized into four or more poles.

Conventionally, in manufacturing such a multi-pole magnetized permanent magnet, when multi-pole magnetizing the magnet material, the magnetized yoke around which the coil is wound is brought close to the magnet material. Generally, a method of magnetizing by passing a large current in a pulsed manner to the magnetized yoke is generally adopted.However, in order to effectively bring out the magnet characteristics of the magnet material, a magnetic field is applied until the magnet is saturated. Must be applied.
For this purpose, it is necessary to flow a large current depending on the magnet material. In this case, it is necessary to increase the number of coil turns of the magnetized yoke or increase the coil wire diameter.

However, in the case of a small magnet or a magnet having a large number of poles, since the size of the magnetized yoke is limited, the number of coil turns and the coil wire diameter can be restricted. In some cases, the effective magnet capability of the magnet material cannot be maximized.

In addition, in the case of an isotropic magnet, it is not always necessary to form a magnetic path after magnetization, and it is not always possible to sufficiently bring out the ability to come from the magnet shape.

[0008]

Conventionally, when a magnet material is multipolar magnetized by a magnetized yoke, the coil wire diameter, the number of turns of the coil, the shape of the yoke, and the like of the magnetized yoke around which the coil is wound are devised. Efforts have been made to draw out more of the capabilities of the magnet material, such as by providing a back yoke on the opposite side of the magnetized yoke with the material in between, but it is still insufficient. There has been a problem that the development of a magnetizing method that can extract more is desired.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to further enhance the capability of a magnet material when magnetizing a magnet material with a magnetized yoke. Accordingly, it is an object of the present invention to obtain a permanent magnet having better magnet properties.

[0010]

According to the multipole magnetizing method of the present invention, when a magnet material having an arbitrary shape such as a ring shape is multipolar magnetized by a magnetizing yoke, the magnetizing yoke is used. The present invention is characterized in that a back yoke is provided on the opposite side and magnetized once, and then magnetized again without providing a back yoke. And

In the multipolar magnetizing method according to the second aspect of the present invention, when a magnet material having an arbitrary shape such as a ring is multipolar magnetized by a magnetizing yoke, the magnet material is magnetized once without providing a back yoke. After that, a back yoke is provided on the opposite side of the magnetized yoke to re-magnetize, and this configuration of the invention is another means for solving the conventional problems.

[0012]

The multipolar magnetizing method according to the present invention has the above-described structure, and includes a step of providing a back yoke on the side opposite to the magnetized yoke with a magnet material interposed therebetween, and providing the back yoke. The step of magnetizing without any one of the steps is performed first, and the step of performing the magnetization is performed after the other step. Therefore, when magnetizing from the outer peripheral side of the ring-shaped magnet material, FIG. As shown in the figure, in the step of providing the back yoke 3 on the side opposite to the magnetized yoke 2 with the magnet material 1 interposed therebetween, the magnetic path 4 is easily formed up to the back yoke 3 so that the magnetic path 4 can be formed in the radial direction. Since the magnetic path 4 becomes shorter in the thickness direction of the magnet material 1, the magnetic flux on the surface decreases, and the magnetization becomes closer to the radially anisotropic magnetization, and as shown in FIG. Without the back yoke, the magnetized yoke 2 In the step of magnetizing the timber 1, the magnetic path 4
Is formed near the outer periphery and the magnetic path of the magnetized portion is long and the surface magnetic flux is relatively large, but the inner periphery (shaded portion) is not magnetized, and the magnet performance is sufficient. However, in the present invention, FIG.
As shown in FIG. 1, by performing the magnetization using the back yoke 3 shown in FIG. 1 and the magnetization not using the back yoke shown in FIG. 2, the unmagnetized portion is eliminated, and the magnetic path 4 can be lengthened. As a result, the surface magnetic flux is improved and the magnet material 1
The magnetic properties possessed by the above can be derived more.

Therefore, according to the method of the present invention, if the magnet characteristics are the same as the conventional one, the desired magnet characteristics can be obtained by magnetizing with a lower voltage or a lower current. The service life will increase,
Further, when the magnet is magnetized with the same voltage or the same current as in the conventional case, the magnet characteristics are extracted more than in the conventional case, so that the magnet characteristics are improved or the size of the magnet is reduced.

[0014]

EXAMPLES Example 1 27% by weight Nd-5% by weight Co-0.9% by weight B-Fe
2.0% by weight of an epoxy resin as a thermosetting resin is added to a rare earth magnet powder having the following composition, pressed into a ring shape, and heated in argon at 150 ° C. for 1 hour to cure the epoxy resin. 20m
m, inner diameter: 18 mm, width: 5 mm
A d-Fe-B based bonded magnet material was obtained.

Next, as shown in FIG. 4, a magnetized yoke 2 around which a coil is wound is provided on the inner peripheral side of the ring-shaped magnet raw material 1 and the outer peripheral side of the magnet raw material 1 (that is, the magnet raw material 1 is removed). The back yoke 3 made of iron is provided on the opposite side of the magnetization yoke 2), the first 12-pole magnetization is performed under the magnetization conditions of 1800 V and 1000 μF, and then the back yoke 3 on the outer peripheral side is removed. The second 12-pole magnetizing was performed under the magnetizing conditions of 1800 V and 1000 μF.

Next, the average value of the peak values of the magnetic flux density waveform on the inner peripheral surface of the ring-shaped permanent magnet obtained after the magnetization was examined. As shown in column 1, 2730 Gauss was obtained.

Embodiment 2 A magnetized yoke 2 in which a coil is wound is provided on the inner periphery of the same ring-shaped magnet material 1 as in Embodiment 1, and the back yoke 3 is not provided on the outer periphery of the magnet material 1 at 1800 V. , 1000μ
After performing the first 12-pole magnetization under the magnetization condition of F, a back yoke 3 is provided on the outer peripheral side of
The second 12-pole magnetizing was performed under the magnetizing conditions of 0 V and 1000 μF.

Next, the average value of the peak values of the magnetic flux density waveform on the inner peripheral surface of the ring-shaped permanent magnet obtained after the magnetization was examined. As shown in column 2, 2750 Gauss was obtained.

COMPARATIVE EXAMPLE 1 A magnetized yoke 2 wound with a coil is provided on the inner peripheral side of the same ring-shaped magnet material 1 as in Example 1, and the back yoke 3 is not provided on the outer peripheral side of the magnet material 1 at 1800 V , 1000μ
After performing 12-pole magnetization under the magnetizing condition of F, the average value of the peak values of the magnetic flux density waveforms on the inner peripheral surface of the ring-shaped permanent magnet obtained by this was examined. . As shown in column 1, it was 2190 Gauss.

Comparative Example 2 The inner peripheral side magnetizing in Comparative Example 1 was performed twice, and the average value of the peak values of the magnetic flux density waveforms on the inner peripheral side surface of the ring-shaped permanent magnet obtained by this was examined. Comparative Example No. 1 in Table 1. As shown in column 2, even when magnetization was performed twice under the same condition at 2190 Gauss, the comparative example N
o. Same as 1

Comparative Example 3 A magnetized yoke 2 wound with a coil was provided on the inner peripheral side of the same ring-shaped magnet material 1 as in Example 1, and a back yoke 3 was provided on the outer peripheral side of the same magnet material 1. , 100
After performing 12-pole magnetization under the magnetization condition of 0 μF, the average value of the peak value of the magnetic flux density waveform on the inner peripheral surface of the obtained ring-shaped permanent magnet was examined. . As shown in column 3, it was 2070 Gauss.

COMPARATIVE EXAMPLE 4 The inner peripheral side magnetizing in Comparative Example 2 was performed twice, and the average value of the peak value of the magnetic flux density waveform on the inner peripheral side surface of the ring-shaped permanent magnet obtained by this was examined. Comparative Example No. 1 in Table 1. As shown in column 4, even when magnetizing was performed twice under the same conditions with 2070 Gauss, the comparative example N
o. The same as in the case of 3.

[0023]

[Table 1]

Example 3 27% by weight Nd-5% by weight Co-0.9% by weight B-Fe
2.0% by weight of an epoxy resin as a thermosetting resin is added to a rare earth magnet powder having the following composition, pressed into a ring shape, and heated in argon at 150 ° C. for 1 hour to cure the epoxy resin. Due to outer diameter; 35m
An Nd-Fe-B-based bonded magnet material having a flat ring shape having a diameter of 15 mm and a thickness of 2 mm was obtained.

Next, as shown in FIG. 5, a magnetized yoke 2 wound with a coil is provided on one side of the flat ring-shaped magnet material 1, and the opposite side of the magnet material 1 (that is, the magnet material 1 is removed). The back yoke 3 is provided on the opposite side of the magnetized yoke 2), the first 8-pole magnetization is performed under the magnetizing conditions of 2000 V and 1000 μF, and then the back yoke 3 on the opposite surface is removed. , 2000 V, 1000 μF, the second 8-pole magnetization was performed.

Next, the average value of the peak value of the magnetic flux density waveform on one surface of the flat ring-shaped permanent magnet obtained after the magnetization was examined. As shown in column 11, 1820 Gauss was obtained.

Embodiment 4 A magnetized yoke 2 wound with a coil is provided on one side of the same flat ring-shaped magnet material 1 as in Embodiment 3, and the back yoke 3 is not provided on the opposite surface of the magnet material 1. 2000V, 10
After the first 8-pole magnetization was performed under the magnetizing condition of 00 μF, the back yoke 3 was provided on the opposite side of the magnet material 1 to perform the second 8-pole magnetization under the magnetizing condition of 2000 V and 1000 μF. Made magnetism.

Next, the average value of the peak value of the magnetic flux density waveform on one surface of the flat ring-shaped permanent magnet obtained after the magnetization was examined. As shown in column 12, 1810 Gauss was obtained.

Comparative Example 5 A magnetized yoke 2 wound with a coil was provided on one side of the same flat ring-shaped magnet material 1 as in Example 3, and a back yoke 3 was not provided on the opposite surface of the magnet material 1. 2000V, 10
After performing 8-pole magnetization under the magnetizing condition of 00 μF, the average value of the peak value of the magnetic flux density waveform on the one surface of the flat ring-shaped permanent magnet obtained by this was examined.
Comparative Example No. As shown in column 11, 1020 Gau
ss.

Comparative Example 6 The single-sided magnetization in Comparative Example 5 was performed twice, and the average value of the peak value of the magnetic flux density waveform on the single-sided surface of the obtained flat ring-shaped permanent magnet was examined. Comparative Example No. 2 of No. 2 As shown in column 12, 1020 Gauss
s, and even when magnetization was performed twice under the same conditions, the comparative example No. 11 was the same.

Comparative Example 7 A magnetized yoke 2 wound with a coil was provided on one side of the same flat ring-shaped magnet material 1 as in Example 3, and a back yoke 3 was provided on the opposite surface of the magnet material 1. 2000V,
After performing 8-pole magnetization under the magnetization condition of 1000 μF, the average value of the peak value of the magnetic flux density waveform on the one surface of the obtained flat ring-shaped permanent magnet was examined.
Comparative Example No. 2 in Table 2. As shown in column 13, 1560G
auss.

Comparative Example 8 The single-sided magnetization in Comparative Example 7 was performed twice, and the average value of the peak value of the magnetic flux density waveform on the single-sided surface of the obtained flat ring-shaped permanent magnet was determined. Comparative Example No. 2 of No. 2 As shown in column 14, 1560 Gauss
s, and even when magnetization was performed twice under the same conditions, the comparative example No. 7 was the same.

[0033]

[Table 2]

[0034]

According to the multipolar magnetizing method according to the present invention,
Since the above configuration is adopted, the step of providing a back yoke on the side opposite to the magnetization yoke with the magnet material interposed therebetween and the step of performing magnetization without providing the back yoke are used in combination, so Since the magnetic portion is eliminated and the magnetic path can be made long, the surface magnetic flux is improved, and the magnet characteristics of the magnet material can be further extracted.

Therefore, if the same magnet characteristics as those of the related art can be achieved, desired magnet characteristics can be obtained by magnetizing with a lower voltage or a lower current, so that the life of the magnetized yoke can be extended. When magnetizing with the same voltage or the same current as in the past, the magnet properties are more extracted than in the past, and the magnet properties are improved or the magnet is downsized. A markedly superior effect is achieved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a state of formation of a magnetic path in a case where a back yoke is provided on a side opposite to a magnetized yoke with a magnet material interposed therebetween and magnetized.

FIG. 2 is an explanatory diagram showing a state of forming a magnetic path when magnetizing without providing a back yoke.

FIG. 3 shows a state of forming a magnetic path in an example of the present invention in which a step of providing a back yoke on the side opposite to a magnetization yoke with a magnet material interposed and a step of performing magnetization without providing a back yoke are used in combination. FIG.

FIG. 4 is an explanatory diagram showing a magnetizing method in Examples 1 and 2 and Comparative Examples 1 to 4 of the present invention.

FIG. 5 is an explanatory diagram showing a magnetizing method in Examples 3 and 4 and Comparative Examples 5 to 8 of the present invention.

[Explanation of symbols]

 Reference Signs List 1 magnet material 2 magnetized yoke 3 back yoke 4 magnetic path

Claims (2)

(57) [Claims] When a magnet material is multipolarly magnetized by a magnetized yoke, it is preferable that a back yoke is provided on the opposite side of the magnetized yoke, magnetized once, and then magnetized again without providing a back yoke. Characteristic multi-pole magnetization method. 2. When multi-polarizing a magnet material using a magnetized yoke, the magnet material is magnetized once without providing a back yoke,
A multi-pole magnetizing method, wherein a back yoke is provided on the opposite side of the magnetized yoke and magnetized again.