JP2000260617A - Manufacture of anisotropic oxide permanent magnet and metal mold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a method of manufacturing an anisotropic oxide permanent magnet, capable of molding a number of products having uniform magnetic characteristics by improving magnetic pole constitution for magnetic field orientation, and a metallic mold for the same. SOLUTION: A metal mold is used which comprises a mortar 1 in which a pair of magnetic poles 2 for magnetic field orientation are placed and in which a plurality of roughly cylindrical molding spaces 3 are formed in an arrangement of one column or two columns in the direction normal to the magnetic path direction. Each of the magnetic poles 2 has a width that comprises the width corresponding to the roughly cylindrical molding spaces 3 and a pair of additional magnetic-pole width Wa, which is 0.3-1.5 times the magnetic-pole width W for one piece of the molding space, in both end parts. Material powder of oxide permanent magnet or slurry containing the powder is charged in the roughly cylindrical molding spaces, and is molded under an orientating magnetic field produced by the pair of magnetic poles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a cylindrical anisotropic oxide permanent magnet used for a two-pole motor or the like, and a molding die. The present invention relates to a method for manufacturing an anisotropic oxide permanent magnet and a molding die capable of greatly improving the production efficiency of a permanent magnet.

[0002]

2. Description of the Related Art Conventionally, as a mold structure of a cylindrical bipolar anisotropic magnet, there is one disclosed in JP-A-6-260328.
A product is obtained by a mold in which magnetic materials are arranged in pairs in the magnetization direction of the outer peripheral portion of the elliptical molding space between a pair of magnetic poles (magnetic paths), and nonmagnetic materials are arranged in pairs perpendicular to the magnetization direction. Like that. In this case, it is stated that a cylindrical two-pole anisotropic magnet which improves the total magnetic flux generated from the magnetic pole surface and improves the cogging characteristics of the motor can be manufactured with high productivity.

Japanese Patent Application Laid-Open No. Sho 60-176206 discloses that in a mold structure of a cylindrical bipolar anisotropic magnet, the center of a molding space between a pair of magnetic poles (magnetic path) or the magnetization direction of the molding space is determined. It discloses a mold in which a part of the outside is made of a magnetic material.
According to the publication, a total magnetic flux amount larger than that of the conventional product can be obtained, the power consumption can be reduced by incorporating the magnetic flux into a coreless motor, and an inexpensive magnet can be provided by downsizing.

Further, Japanese Utility Model Laid-Open No. 55-58322 discloses that
A configuration in which a plurality of ring-shaped cavities are arranged in a mold for injection molding is disclosed. However, the feature of this mold is that the magnetic force lines efficiently flow in the diameter direction of the ring-shaped cavity by a combination of a magnetic material and a non-magnetic material which are divided into a plurality in the diameter direction of the ring-shaped cavity and arranged in parallel with each other. For this reason, no particular consideration has been given to the configuration of the magnetic poles for magnetic field orientation to prevent variations in the characteristics of a plurality of molded articles simultaneously molded.

[0005]

By the way, Japanese Patent Application Laid-Open No.
No. 260328 and Japanese Patent Application Laid-Open No. 60-176206 disclose a technique for simultaneous molding of a large number of pieces, and the metal mold structure disclosed in Japanese Utility Model Application Laid-Open No. 55-58322 has a magnetic pole configuration for magnetic field orientation. No consideration is given to improving the productivity of products with uniform magnetic properties by molding many pieces.

SUMMARY OF THE INVENTION In view of the above, the present invention provides a method for manufacturing an anisotropic oxide permanent magnet, which is capable of molding a large number of products having uniform magnetic properties by improving a magnetic pole configuration for magnetic field orientation. And a mold for molding.

[0007] Other objects and novel features of the present invention will be clarified in embodiments described later.

[0008]

In order to achieve the above object, a method for producing an anisotropic oxide permanent magnet according to the present invention comprises: a mortar provided with a pair of magnetic poles for magnetic field orientation; A plurality of substantially cylindrical molding spaces are provided in one or two rows in the orthogonal direction, and the magnetic poles have a width corresponding to the plurality of substantially cylindrical molding spaces and a magnetic pole width of 0 for the one molding space. Using a molding die having additional magnetic pole portions of 0.3 to 1.5 times at both ends in the width direction, the substantially cylindrical molding space is filled with oxide permanent magnet material powder or a slurry containing the powder, respectively. The molding is performed in an orientation magnetic field by the pair of magnetic poles.

A mold for molding an anisotropic oxide permanent magnet according to the present invention is a mold having a pair of magnetic poles for orienting a magnetic field, and a plurality of substantially cylindrical molding spaces perpendicular to a magnetic path direction. Are provided in one or two rows, and the magnetic poles have widths corresponding to a plurality of substantially cylindrical molding spaces and additional magnetic pole portions that are 0.3 to 1.5 times the width of the molding space at both ends in the width direction. Is provided.

In the mold for molding an anisotropic oxide permanent magnet, an intermediate magnetic pole is arranged at an intermediate position between the pair of magnetic poles for magnetic field orientation, and the plurality of substantially cylindrical molding spaces are sandwiched by the intermediate magnetic pole. May be arranged in two rows.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a method for manufacturing an anisotropic oxide permanent magnet according to the present invention;

A first embodiment of the present invention will be described with reference to FIGS. In these figures, 1 is a mortar, 2
Is a pair of magnetic poles for magnetic field orientation, and 3 is a substantially cylindrical molding space. Here, the tip surfaces of the pair of magnetic poles 2 for magnetic field orientation are parallel, and the molding holes 1a of the non-magnetic die 1 for forming the molding space 3 are perpendicular to the direction of the magnetic path, that is, A plurality of magnetic poles 2 are arranged in a row in parallel with the end surface. As shown in FIG. 2, a non-magnetic center rod 10 has entered the center of the molding hole 1 a of the non-magnetic die 1, and
A non-magnetic lower punch 11 is fitted on the outer peripheral side of the body, and a non-magnetic upper punch 12 is fittable.
Thus, the substantially cylindrical molding space 3 is formed. The pair of magnetic poles 2 for magnetic field orientation are buried in a non-magnetic mortar 1, and are energized by a coil (not shown) such that one end of the magnetic pole is an N pole and the other end is an S pole. As a result, a magnetic flux is generated from the N pole to the S pole, that is, crossing the substantially cylindrical molding space 3. The pair of magnetic poles 2 for magnetic field orientation
Is the magnetic pole width W corresponding to one molding space in addition to the magnetic pole widths corresponding to the plurality of substantially cylindrical molding spaces 3 {for example, the width of the molding space itself + a few mm (about 1 to 3 mm)}. 0.3-1.
A five-fold additional magnetic pole portion 2a (indicated by Wa in FIG. 1) is provided at both ends in the width direction.

Incidentally, the mortar 1, the middle rod 10, which is a non-magnetic material,
The material of the lower punch 11 and the upper punch 12 is not particularly limited, and for example, stainless steel, copper beryllium steel, high manganese steel, bronze, brass, nonmagnetic super steel, or the like can be used.

Each of the molding spaces 3 formed by such a mold structure is filled with an oxide permanent magnet material powder, and molded in an orientation magnetic field by a pair of magnetic poles 2 for magnetic field orientation, whereby characteristics are improved. A large number of uniform anisotropic oxide permanent magnets can be obtained simultaneously.

The number n of the molding spaces 3 is such that the strength of the magnetic field generated in the molding space is sufficient to orient the magnet material.
There is no particular limitation as long as there is no particular problem as the final product.
When the magnetic field generating coils that excite the magnetic poles for magnetic field orientation 2 are the same, the smaller the individual molding space, the larger the number n that can be arranged, and conversely, the larger the molding space, the smaller the number n. As an example, in a molding space having an outer diameter of about 20 mm, there are 5 to 7 pieces per row. The number n also differs depending on the material used for the magnetic path, in other words, the magnetic pole 2 for magnetic field orientation.

The additional magnetic pole portion 2a has no effect if it is too small, but it is useless if it is too large. That is, if the magnetic pole width W is less than 0.3 times the magnetic pole width W corresponding to one molding space 3, the magnetic field in the molding space is strongly affected by the reduced magnetic field from the outside, and the surface magnetic flux of the molded product located at the end portion is strong. The waveform is distorted, and the surface magnetic flux waveform of a molded product other than the end is different. Conversely, if it is too large, the influence of the magnetic field is not affected in the molding space at the end, but the strength of the magnetic field in the entire molding space is reduced, so it is not so good, and 1.5 times is sufficient.

According to the first embodiment, the following effects can be obtained.

(1) By forming a mold structure in which a large number of molding spaces 3 are arranged in a row in a direction perpendicular to the magnetic path direction as described above,
A large number of anisotropic oxide permanent magnets can be molded at a time, greatly improving productivity. For example, if n pieces are arranged in one row, n pieces can be obtained.

(2) A pair of magnetic poles for magnetic field orientation 2 has an additional magnetic pole portion 0.3 to 1.5 times the magnetic pole width W of one molding space in addition to the width corresponding to the plurality of molding spaces 3. By having 2a at both ends in the width direction, the surface magnetic flux of all the molded products of multiple molding including those molded in the molding spaces located at both ends of the mold becomes uniform.

FIG. 3 shows a second embodiment of the present invention.
In this case, a molding hole 1a of the non-magnetic mortar mold 1 for forming the substantially cylindrical molding space 3 is provided between the parallel tip surfaces of the pair of magnetic poles 2 for magnetic field orientation in a direction perpendicular to the magnetic path direction. That is, a plurality of magnetic poles 2 are arranged in two rows in parallel with the tip end surface. An intermediate magnetic pole 20 is arranged between the first row of molding holes 1a and the second row of molding holes 1a. The intermediate magnetic pole 20 is arranged in parallel with the middle of the pair of magnetic poles 2 for magnetic field orientation, and the number n of substantially cylindrical molding spaces 3 is arranged with the intermediate magnetic pole 20 interposed therebetween. Here, the thickness of the intermediate magnetic pole 20 in the direction of the magnetic path is set to 0.5 or more of the molding space 3. Further, in addition to the width corresponding to the number n of the molding spaces 3 in one row, the magnetic pole width of one molding space 3 is added. The width of the intermediate magnetic pole 20 is substantially the same as that of the magnetic pole 2 for magnetic field orientation having additional magnetic pole portions 2a (indicated by Wa in FIG. 3) of 0.3 to 1.5 times W.
Is formed.

When the molding spaces are arranged in two rows, the intermediate magnetic pole 2
If the thickness in the magnetic path direction of 0 is small, the magnetic field is likely to be disturbed. If it is larger than 0.5 times, no particular problem occurs.

The arrangement of the upper and lower punches and the inner rods in the individual molding spaces 3 may be the same as in FIG.

According to the second embodiment, by arranging the molding space 3 of the number n in two rows, it is possible to simultaneously mold n × 2 molded products having a uniform surface magnetic flux.

FIGS. 4A, 4B and 4C show a conventional example and a comparative example, respectively, for comparison with the embodiment. In the conventional example shown in FIG. 1A, there is one substantially cylindrical molding space 3 and 1
In this configuration, a pair of magnetic poles for magnetic field orientation 2 having a magnetic pole width corresponding to each molding space is provided. In this case, it is a configuration in which multiple molding cannot be performed. FIG. 4B shows a first comparative example in which a plurality of substantially cylindrical molding spaces 3 are arranged in a row between a pair of magnetic poles 2 for magnetic field orientation. There is no consideration, and the magnetic pole width is only the magnetic pole width with respect to the molding space, and there is no additional magnetic pole portion. FIG. 7C shows a second comparative example, in which the width of the magnetic pole corresponding to one molding space is set at the both ends in the width direction of the pair of magnetic poles 2 for magnetic field orientation.
2x additional magnetic pole portion 2b (additional magnetic flux portion with insufficient width)
have.

[0025]

FIG. 1 (the mold described in the first embodiment),
3 (the mold described in the second embodiment), FIG.
Molding was attempted using the molds of the conventional examples (A), (B), and (C), the first comparative example, and the second comparative example. Fig. 4
In (A), n = 1, and in other cases, n = 3. The outer diameter of the molding space was 22.7 mm, the inner diameter was 7.32 mm, and the molding machine including the magnetic field generating coil was the same.

Each mold was tried under the same molding conditions (100 samples), and the surface magnetic flux waveform of each sample was measured using a Hall element. The measurement results are as shown in Table 1 below.

Table 1 (100 shots) First comparative example Second comparative example Embodiment No additional magnetic pole Additional magnetic pole 0.2 times Additional magnetic pole 0.3 to 1.5 times Surface flux waveform Symmetry Asymmetric Symmetry Asymmetric Symmetry Asymmetric Number of abnormal occurrences (%) 33 67 76 24 100 0 Symmetry means that when the surface magnetic flux of the outer peripheral surface of the anisotropic oxide permanent magnet after sintering and magnetization is measured in an angle range of 180 degrees, as shown by the solid line in FIG. The both sides of the peak are symmetric, and the asymmetry is the case where both sides of the peak of the surface magnetic flux are asymmetric as indicated by the dotted line in FIG.

According to the mold structure described in each of the above embodiments, a large number of products can be produced by simultaneously molding a large number of products and the molding process time is almost the same, and a large number of molded products can be produced by the additional magnetic pole portion of the magnetic pole for magnetic field orientation. It can be seen that the surface magnetic flux of each of them becomes uniform.

In the present invention, the case of dry molding in which the oxide permanent magnet material powder is filled in a molding space and pressure molding is exemplified, but wet molding in which a slurry containing the powder is filled and pressure molding is performed, respectively. It can be applied to molding.

Although the embodiments of the present invention have been described above, it is obvious to those skilled in the art that the present invention is not limited to the embodiments and various modifications and changes can be made within the scope of the claims. There will be.

[0031]

As described above, according to the present invention,
In a mortar provided with a pair of magnetic poles for magnetic field orientation, a plurality of substantially cylindrical molding spaces are provided in one or two rows in a direction orthogonal to a magnetic path direction, and the magnetic poles are formed of a plurality of substantially cylindrical molding spaces. In addition to the width corresponding to the above, the magnetic pole width of 0.3 to 1.
Using a molding die having 5 times additional magnetic pole portions at both ends in the width direction, the substantially cylindrical molding space is filled with the oxide permanent magnet material powder or the slurry containing the powder, and the pair of magnetic poles is used. By molding in an orientation magnetic field, a large number of anisotropic oxide permanent magnets having uniform surface magnetic flux and uniform characteristics can be molded at a time, and productivity can be greatly improved. As a result, it is possible to improve the total magnetic flux generated from the magnetic pole surface and improve the cogging characteristics of the motor.
Polar anisotropic magnets can be manufactured with high productivity.

[Brief description of the drawings]

FIG. 1 is a schematic plan view showing a method for manufacturing an anisotropic oxide permanent magnet and a molding die according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing the configuration of each molding space in the first embodiment.

FIG. 3 is a schematic plan view showing a second embodiment of the present invention.

FIG. 4 is a schematic plan view showing a conventional example and a comparative example.

FIG. 5 is a graph showing a symmetric waveform and an asymmetric waveform of the surface magnetic flux on the outer peripheral surface of the anisotropic oxide permanent magnet.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mortar type 1a Molding hole 2 Magnetic pole for magnetic field orientation 2a Additional magnetic pole part 3 Substantially cylindrical molding space 10 Middle rod 11 Lower punch 12 Upper punch

Claims (3)

[Claims] 1. A mortar provided with a pair of magnetic poles for magnetic field orientation,
A plurality of substantially cylindrical molding spaces are provided in one or two rows in a direction orthogonal to the direction of the magnetic path, and the magnetic poles have a width corresponding to the plurality of substantially cylindrical molding spaces and a width corresponding to one molding space. A permanent magnet material powder or a slurry containing the powder in the substantially cylindrical molding space by using a molding die having additional magnetic pole portions 0.3 to 1.5 times the magnetic pole width at both ends in the width direction. And molding in an orientation magnetic field by the pair of magnetic poles. 2. A mortar provided with a pair of magnetic poles for magnetic field orientation,
A plurality of substantially cylindrical molding spaces are provided in one or two rows in a direction orthogonal to the magnetic path direction, and the magnetic poles have a width corresponding to the plurality of substantially cylindrical molding spaces and a width of the molding space. 0.3
A mold for molding an anisotropic oxide permanent magnet, comprising an additional magnetic pole portion of about 1.5 times at both ends in the width direction. 3. The magnetic head according to claim 2, wherein an intermediate magnetic pole is arranged at an intermediate position between the pair of magnetic poles for magnetic field orientation, and the plurality of substantially cylindrical molding spaces are arranged in two rows with the intermediate magnetic pole interposed therebetween. Mold for molding anisotropic oxide permanent magnets.