JPH06338408A - Permanent magnet and manufacturing method thereof - Google Patents

Abstract

(57) [Summary] [Structure] A bulk magnet such as a sintered magnet is molded so as to be covered with a bonded magnet material composed of magnetic powder and a binder. Further, the bulk magnets are arranged by using a magnet or the like, covered with a bond magnet material, and magnetized according to the position of the bulk magnet. [Effect] It has higher magnetic properties or magnetic flux than bonded magnets, and has the effects of mechanical strength and weight reduction that bulk magnets do not have, and it can be used in applications such as higher performance of applied products equipped with it. It has a great effect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet and its manufacturing method.

[0002]

2. Description of the Related Art Heretofore, as a method of forming a permanent magnet with a magnetic material and a binder, a magnet called a resin-bonded magnet or a bonded magnet has been well known. In recent years, only a metal material centered on a sintered magnet has been used. It is produced at a higher growth rate than the bulk magnet.

[0003]

However, the permanent magnets in the prior art have the following problems.

(1) In a so-called bonded magnet consisting of a magnetic material and a binder, the ratio of the binder to the magnetic material is 10 to 50% by volume, but the binder generally does not contribute to the magnetic properties. Therefore, the larger the amount of binder, the lower the magnetic properties of the permanent magnet obtained.

(2) In the case of a bulk magnet made of 100% metal material represented by a sintered magnet and containing no binder, cracking and chipping are likely to occur, the specific gravity is large, and secondary processing is required.

Therefore, the present invention solves such a problem, and an object of the present invention is to lower the magnetic characteristics while utilizing the advantages of the bonded magnet such as a high degree of freedom in shape and the need for secondary processing. SUMMARY OF THE INVENTION It is an object of the present invention to provide a permanent magnet and a method for manufacturing the same, which make up for the weakness.

[0007]

The permanent magnet of the present invention is characterized in that one or more bulk magnets are covered with a bonded magnet material comprising a magnetic powder and a binder. Further, it is characterized in that they are arranged regularly, or they are arranged annularly and have a ring shape.

In the method for producing a permanent magnet material, magnetism is generated in a part of a molding die and / or jig, and the bulk magnets are magnetically attracted to the magnets so that they are regularly arranged and covered with the bond magnet material. It is characterized by The magnetism is generated by a permanent magnet and / or an electromagnet. Further, the present invention is characterized in that the bulk magnet is covered with the above-mentioned bonded magnet material, and at the same time, it is integrally molded with a component such as a shaft or a yoke, or bonded simultaneously with molding and curing.

[0009]

The above structure of the present invention has the following effects.

(1) By covering the bulk magnet with the bonded magnet material, the ratio of the magnetic material can be increased as compared with the bonded magnet material alone, so that the magnetic characteristics can be improved.

(2) Macroscopically, the bonded magnet material is bonded with a binder, and the surface of the magnet is covered with the bonded magnet material. Therefore, cracking or chipping occurs as compared with a bulk magnet represented by sintering. Is easy to handle. Even in application, there is no need to worry about dust generation due to damage during use or loss of magnetic powder, and no dust coating is required.

(3) At the same time as covering the bulk magnet with the bonded magnet material, it is possible to perform integral molding, which is one of the features of the bonded magnet.

(4) By magnetizing in accordance with the arrangement of the bulk-shaped magnets, the magnetic flux has a strength comparable to that of the bulk-shaped magnets. By devising the previous arrangement and the magnetization, for example, various trapezoidal waves can be obtained. It is possible to obtain various magnetization patterns.

(5) Since the magnetic flux is generated as much as that of a bulk magnet, the weight of the bonded magnet material is reduced, so that the weight can be reduced. For example, in the application to the rotor magnet, the weight of the inertia can be reduced.

[0015]

EXAMPLES The present invention will be described in detail below based on examples.

Example 1 Sm (Co _0.68 Fe _0.3 Cu
_0.05 Zr _0.02 ) The alloy is melted and cast in a high frequency melting furnace so as to have a composition of _7.5 Zr _0.02 ), pulverized into powder of 3 to 5 μm, and molded with a pressure of 15 kgf / mm ² and a magnetic field of 10 kOe, 1150 to 1250. Sintered for 1 hour at ℃, 1100
The solution treatment was carried out at -12O <0> C for 1 hour and aged at 850 <0> C. The magnetic characteristics of the obtained Sm-based sintered magnet are as follows: Br = 12 kG, iHc = 13 kOe, (BH) max
= 30 MGOe. Comparative Example 1 of this Sm-based sintered (bulk) magnet
And

In each case, the weight percentage is Nd12.4%,
A high-frequency melting furnace was used to melt and cast in an argon gas atmosphere so that the composition of Co was 15.9%, B 5.8%, and the balance of Fe was used. Medium, diameter 20mm copper roll, quartz tube orifice diameter 0.6mm, argon injection pressure 4
A quenched ribbon was prepared under conditions such as kgf / cm ^2, crushed and heat-treated to obtain an Nd-based magnetic powder. 2% by weight of an epoxy resin was added to this powder, which was mixed and kneaded to obtain a compound for compression molding. 50 kgf / m of this compound
It was compression molded at a pressure of m ² and cured at 150 ° C. for 1 hour to obtain an Nd-based compression molded bond magnet. The magnetic characteristics are as follows: Br = 7.7 kG, iHc = 10 kOe, (BH) ma
x = 12 MGOe. This Nd-based compression molded bonded magnet is referred to as Comparative Example 2.

Further, 22% by volume of holamide 12 was mixed and kneaded with this Nd-based magnetic powder to prepare a compound for injection molding. This compound was injection-molded to obtain an Nd-based injection-molded bond magnet. The magnetic characteristics are as follows: Br = 7 kG, iHc = 10 kOe, (BH) max =
It was 10 MGOe. This is Comparative Example 3.

Next, the Sm-based sintered magnet (bulk-shaped magnet) of Comparative Example 1 was formed into a cube of 2 mm square, and the Nd-based compression molding compound of Comparative Example 2 (bonded magnet material) was molded to cover it. It was The volume ratio was 1: 1 by volume. Specifically, first, only half of the Nd-based compression molding compound was put into the molding die, the Sm-based sintered magnet was put therein, and the rest of the Nd-based compression molding compound was put in the molding die.
Molding was performed at a pressure of 50 kgf / mm ² while applying a magnetic field of 5 kOe. The magnetic characteristics are as follows: Br = 10 kG, iHc = 10.5 kOe, (BH) m
It was ax = 19MGOe. This is referred to as Invention 1.

Further, similarly, molding was performed so that the Sm-based sintered magnet of Comparative Example 1 was covered with the Nd-based injection molding compound of Comparative Example 3. The magnetic characteristics are as follows: Br = 9.4 kG, iHc = 10 kOe, (BH) ma
It was x = 16 MGOe. This is referred to as Invention 2.

As described above, the magnetic characteristics are almost intermediate between those of the bulk magnet (Comparative Example 1) and the bonded magnet material (Comparative Examples 2 and 3). Two pieces of each of the five kinds of magnet samples were magnetized, and the hands were separated from the distance of 10 cm to be magnetically adsorbed. In Comparative Example 1, the corner was chipped once, but other magnets did not change even after repeated five times. That is, it is understood that the present inventions 1 and 2 have higher magnetic characteristics and mechanical strength comparable to that of the bonded magnet, as compared with the bonded magnet.

Example 2 Nd ₁₃ Dy ₂ Fe ₇₀ Co ₈ B ₇
The ingot thus obtained was melted and cast so as to have the composition of No. 1, and the obtained ingot was crushed to 2-3 μm, molded in a magnetic field as in Example 1, sintered at 1100 ° C. for 3 hours, and heat-treated at 600 ° C. for 1 hour. did. The magnetic characteristics are as follows: Br = 12.6 kG, iHc = 21 kOe, (BH) m
It was ax = 36MGOe. This Nd-based sintered magnet is referred to as Comparative Example 4.

Sm (Co _0.586 Fe _0.32 Cu _0.08 Zr
_0.016 ) Melt and cast the alloy in a high frequency melting furnace so that it has a composition of _8.35 , and solution heat treatment at 1150 ° C for 24 hours,
Aged at 800 ℃ for 8 hours,
It was cooled to 0 ° C. at a cooling rate of 0.5 ° C./min. The heat-treated ingot was crushed into powder having a size having a particle size distribution of about 20 μm. About 2 parts of epoxy resin is added to the obtained powder.
Weight% was added, mixed and kneaded to obtain a compound.
This compound is applied at a pressure of 50 kgf / mm ^{2 and} a pressure of 15 k
Magnetic field molding is performed with a magnetic field of Oe, and the molded body is demagnetized.
It was cured at 0 ° C. for 1 hour. The magnetic characteristics are as follows: Br = 9.4 kG, iHc = 12 kOe, (BH) ma
It was x = 18 MGOe. This Sm-based compression molded bonded magnet is referred to as Comparative Example 5.

A magnet obtained by covering the Nd-based sintered magnet of Comparative Example 4 with the Sm-based compression molded bonded magnet of Comparative Example 5 was used.
Created in the same way. This is referred to as Present Invention 3. In terms of magnetic properties, (BH) max = 27MGOe, which is low compared to Comparative Example 4, but higher than that of Comparative Example 5.

Two magnets each having a side length of 30 and 50 mm, a height of 30 mm, and a thickness of 3 mm were prepared and mounted on a rotary type VCM, and the characteristics of the above three types of magnets were compared. . The Nd-based sintered magnet of Comparative Example 4 had a gap magnetic flux density of about 5900 G, whereas the present invention 3 has about 5
The value was almost the same as that of 600G. The Sm-based bonded magnet of Comparative Example 5 had a low value of about 4000G. Further, the torque of Comparative Example 4 was 460 g · cm / amp, but the present invention 3 was used.
Was almost the same value as 440 g · cm / amp.

As to other characteristics, while Comparative Example 4 required secondary processing and coating after sintering,
Neither of the present invention 3 was necessary. Also, the bonding step could be omitted by molding and curing on the yoke during molding.

(Embodiment 3) In all cases, the weight percentage is Nd.
12.4%, Co 15.9%, B 5.8% and balance Fe
The composition was melted and cast in an argon gas atmosphere using a high-frequency melting furnace, and the obtained ingot was formed into a quenched ribbon in an argon gas atmosphere using a quenching ribbon manufacturing apparatus. The quenched ribbon is crushed and compressed at room temperature into a ring-shaped compact, which is then heated to 750 ° C. in an argon atmosphere.
Rear extrusion molding with outer diameter 22, inner diameter 19, height 4
mm radial anisotropic ring-shaped magnet was prepared. This N
Comparative Example 6 was a d-system quenched hot-worked bulk magnet.

Polyamide 12 was mixed and kneaded with the Sm type magnetic powder of Comparative Example 5 of Example 2 to form a compound, which was used as a radial anisotropic magnet in a magnetic field injection molding machine. This Sm-based injection molded magnet is referred to as Comparative Example 7.

The quenching powder of Comparative Example 6 was die-up set molded to prepare a rectangular parallelepiped Nd-based quenching hot-worked bulk magnet. Width 2.2, so that the thickness direction is anisotropic
Twenty-four plate magnets having a height of 3.6 and a thickness of 1 mm were prepared.
A magnet magnetized to a core with a diameter of 19 mm is installed every 15 degrees, and the above plate magnets are attracted one by one, and the outer diameter is 22 mm
Comparative Example 6 and 7 by transfer molding the Sm-based compound of Comparative Example 7 in combination with the die of
The same ring-shaped magnet was created. This is referred to as Present Invention 4.

Two of these three types of ring-shaped magnets were adhered to the rotor and magnetized with 24 poles. However, in the present invention 4, magnetization was performed in accordance with the position of the embedded Nd-based quenching hot-worked bulk magnet. The rotor magnet was incorporated into a PM type stepping motor, and the characteristics of the motor were evaluated.

Of the pulse rate / torque characteristics, 300
The pullout torque in pps is 900 g in Comparative Example 7.
However, the present invention 4 showed a high value of 1100 g · cm. Comparative Example 6 showed high torque at low pulse rates, but only 400 gcm at 300 pps.

(Example 4) Melting / casting was performed so that the composition was Pr ₁₇ Fe _75.5 B _5.5 Cu ₂ and the obtained ingot was heated at 950 ° C. for 8 hours at 950 ° C. using a hot press in an argon atmosphere.
0% processing was applied. After that, at 1000 ℃ for 20 hours +4
Heat treatment was performed at 75 ° C. for 2 hours. This was processed into a disk shape to obtain an axial anisotropic magnet. This is Comparative Example 8.

Using the compound of Comparative Example 3 of Example 1, the same disk-shaped magnet was produced by the injection molding method. This is Comparative Example 9.

The bulk magnet of Comparative Example 8 was processed into a fan shape having an angle of 60 degrees. Next, magnetism was generated at 6 points on the bottom surface of the disk of the mold of the injection molding machine, the previous bulk magnet was attracted, the rotor shaft was set, and then the compound of Comparative Example 3 was injected to obtain the bulk. At the same time as covering the magnet, it was molded integrally with the shaft. This is referred to as Present Invention 5.

In Comparative Examples 8 and 9, the shaft of the rotor was adhered,
The three types of rotor magnets were magnetized with 6 poles, and then assembled into an axial gap type spindle motor in which 6 coils were arranged at opposing positions.

In Comparative Example 8, the magnetic flux was high and the motor characteristics were good, but cracks and chips were conspicuous, and coating was indispensable when mounting in applied products such as HDD. In Comparative Example 9, the magnetic flux was insufficient and the motor characteristics were also insufficient. For it,
Since the magnetic flux of Inventive Example 5 was sufficiently high, the motor characteristics were similar to those of Comparative Example 8. In addition, since the weight was lighter than that of Comparative Example 8, it was possible to give a great degree of freedom to the design such as setting the inertia.

As described above, the present invention is effective without depending on the magnet material and manufacturing method, and the scope of the present invention is limited only by the claims. It is also clear that it has a great effect on application.

[0038]

As described above, according to the present invention, one or more bulk magnets are covered with a bond magnet material composed of a magnetic powder and a binder. Since the ratio of the magnetic material can be increased as compared with the material alone, the magnetic characteristics can be improved, the magnetic flux can be increased, and compared with the bulk magnet represented by sintering, there is no cracking or chipping, and the weight can be reduced. In the application to magnets, not only the performance can be improved, but also the inertia can be reduced in weight.

[Brief description of drawings]

FIG. 1 is a structural conceptual diagram of a ring-shaped permanent magnet of the present invention.

FIG. 2 is a structural conceptual diagram of a disk-shaped permanent magnet of the present invention.

[Explanation of symbols]

 1 ... Bulk magnet 2 ... Bonded magnet material

Claims (6)

[Claims] 1. A permanent magnet, characterized in that one or more bulk magnets are covered with a bonded magnet material consisting of magnetic powder and a binder. 2. The permanent magnet according to claim 1, wherein the bulk magnets are regularly arranged. 3. The permanent magnet according to claim 1, wherein the bulk magnets are annularly arranged and have a ring shape. 4. A permanent magnet characterized in that magnetism is generated in a part of a molding die and / or jig, and the bulk magnets are magnetically attracted to the magnets so that they are regularly arranged and covered with the bond magnet material. Magnet manufacturing method. 5. The method for producing a permanent magnet material according to claim 4, wherein the magnetism is generated by a permanent magnet and / or an electromagnet. 6. The manufacturing of a permanent magnet according to claim 4, wherein the bulk magnet is covered with the bonded magnet material, and at the same time, it is integrally molded with a component such as a shaft or a yoke or is bonded simultaneously with molding and curing. Method.