JPH0590053A - Die for manufacturing multi-polar aeolotropic magnet - Google Patents

Abstract

PURPOSE:To increase magnetic field in a cavity and enlarge the surface magnetic field of a magnet and manufacture many pieces in one step by permitting the adjacent permanent magnets for orientation to make contact with each other and specifying the width of the edge plane of a yoke on a cavity side. CONSTITUTION:At the time of constituting a cavity 4, even pieces of permanent magnets 1 for orientation are arranged by sandwiching a yoke 2, which is a strong magnetic body, to permit the operating plane of a cylindrical magnet to be multi-polar in the circumferential direction and to have the same polar in the cylinder axis direction. The width of the yoke 2, which is sandwiched by the permanent magnets 1, becomes narrower as it goes further from the cavity side and the yoke 2 makes contact with the permanent magnets 1 which sandwiches the yoke 2 at the outer circumference edge. The width of the yoke 2, which is sandwiched by the permanent magnets 1 at the cavity side edge plane, is permitted to be 20% or more of the circumference for the magnetic pole calculated by dividing the cavity circumference by the magnetic pole number. Thus, many pieces of the multi-polar aeolotropic magnets which have extremely large surface magnetic field are manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold suitable for manufacturing a multipolar anisotropic cylindrical magnet used for a rotor for a motor, a magnet roll or the like.

[0002]

2. Description of the Related Art Conventionally, cylindrical magnets used for motor rotors and magnet rolls have been made multipolar anisotropy in order to increase the generated magnetic field.
Various proposals have been made for the manufacturing mold.
For example, Japanese Patent Laid-Open No. 61-125011 discloses a mold in which permanent magnets having magnetic anisotropy in the radial direction are arranged along the outer periphery of a cylindrical cavity in an alternating arrangement of N poles and S poles. Although disclosed, this method cannot sufficiently raise the magnetic field in the cavity, and the magnetic field generated from the surface of the obtained magnet was not necessarily large.

Further, in Japanese Patent Publication No. 2-59993, a yoke is installed at a position corresponding to a magnetic pole portion around a cavity, and a permanent magnet having different polarities along the circumferential direction is provided outside the yoke. And a method of manufacturing an anisotropic magnet roll using a die in which a permanent magnet is arranged between the yokes so as to form a repulsive magnetic field with the permanent magnet. However, in this method, a part of the magnetic flux from the permanent magnet leaks from the yoke, so that the magnetic field in the cavity cannot be sufficiently increased, and more space is required per cavity because a large number of permanent magnets are arranged. There was a problem that it became difficult to take many pieces as they became large.

Further, Japanese Laid-Open Patent Publication No. 62-186507 discloses a mold in which a permanent magnet is arranged so that the same pole is in contact with five surfaces other than the surface of the rectangular parallelepiped ferromagnetic yoke which faces the cavity. According to this method, the magnetic field in the cavity can be made relatively large, but since a large number of permanent magnets are also arranged, the space required for each cavity becomes large, and it remains difficult to obtain a large number.

[0005]

DISCLOSURE OF THE INVENTION The present invention advantageously solves the above-mentioned problems, and not only can increase the magnetic field in the cavity, but also can be used to produce a large number of multi-pole anisotropic magnets. The purpose is to propose a mold.

[0006]

The inventors of the present invention have conducted various studies to achieve the above object, and as a result, by devising the shape of the ferromagnetic body to be the yoke and the arrangement of the permanent magnets, We have found that the intended purpose can be achieved advantageously. The present invention is based on the above findings.

That is, the gist of the present invention is as follows. 1. An even number of orienting permanent magnets face each other along the inner or outer peripheral surface of the cavity for manufacturing a multi-pole anisotropic cylindrical magnet having an inner or outer peripheral surface as a working surface, with a yoke of a ferromagnetic material between them. In a die assembled in an annular shape so that the magnetic poles to be formed are the same pole, the width of the yoke is gradually narrowed from the cavity side toward the non-cavity side, and at least at the non-cavity side end portion, adjacent orientation permanent magnets are adjacent to each other. And the width of the cavity-side end face of the yoke is 20% of the perimeter of the magnetic pole obtained by dividing the cavity perimeter by the number of magnetic poles.
The mold for producing a multipolar anisotropic magnet as described above. 2. In the above item 1, the die for manufacturing a multi-pole anisotropic magnet, wherein the width of the cavity side end surface of the yoke is 50 to 80% of the perimeter of the magnetic pole obtained by dividing the perimeter of the cavity by the number of magnetic poles. 3. In the above 1 or 2, a mold for producing a multipolar anisotropic magnet, in which a magnet having the same pole as the magnetic pole of an orientation permanent magnet adjacent to the yoke is arranged on the end surface of the yoke in the cylindrical axis direction. 4. In the above 1 or 2, a die for producing a multipolar anisotropic magnet, wherein the orientation direction of the magnetic powder particles of the orientation permanent magnet is inclined by 90 ° or more from the cavity direction with respect to the magnet surface in contact with the yoke.

[0008]

The present invention will be described in detail below with reference to the drawings.
As a typical example of the mold according to the present invention, FIG. 1 shows a vertical cross-section of a mold for injection molding which is suitable for manufacturing a cylindrical magnet having an outer peripheral surface as a working surface, and FIG. A- in FIG.
A section taken along line A ′ is shown in FIG. In the figure, numeral 1 is a permanent magnet for orientation, 2 is a yoke made of a ferromagnetic material, 3 is a die made of a non-magnetic material, 4 is a cavity, 5 is a runner, 6 is a sprue, 7 is a nozzle touch, and 8 is a It is a protruding pin. As shown,
In this mold, the permanent magnet 1 is provided along the outer periphery of the cavity 4.
Are arranged, and the non-magnetic body 3 surrounds them. The cavity 4 is connected to an injection molding machine nozzle through a runner 5, a sprue 6, and a nozzle touch 7, and a molded body is ejected by an ejection pin. In this example, the case where one molded body is obtained is shown, but in the case of multiple production, the sprue 6 and the runner 5 may be branched and the cavities 4 may be arranged side by side.

As shown in FIG. 2A, in the present invention, when the cavity 4 is formed, the working surface of the obtained cylindrical magnet has multiple poles in the circumferential direction and has the same pole in the axial direction of the cylinder. In addition, an even number of permanent magnets 1 for orientation are arranged so that the same poles face each other with a yoke 2 made of a ferromagnetic material interposed therebetween, and the sandwiched yoke 2 serves as a magnetic pole to generate a magnetic field in the cavity 4. It has become. The width of the yoke 2 sandwiched between the permanent magnets 1 becomes narrower as it goes away from the cavity side, and the permanent magnets 1 sandwiching the yoke 2 are in contact with each other at their outer peripheral ends. With such a configuration, the magnetic flux leaking from the yoke 2 is significantly reduced, the magnetic field generated in the cavity 4 can be increased, and the magnetic field generated from the surface of the obtained molded magnet can be increased. is there.

Next, FIG. 3 shows a mold suitable for use in manufacturing a cylindrical magnet having an inner peripheral surface as a working surface in a longitudinal section, and FIG. 4 (a) shows CC of FIG. A section 'is shown, and the section DD' is shown in FIG. In this example, a permanent magnet 1 for orientation is arranged along the inner circumference of a cavity 4 with a yoke 2 made of a ferromagnetic material sandwiched between the permanent magnet 1 and the permanent magnet 1.
Has a shape in which its width gradually narrows as it moves away from the cavity side. With this configuration,
As in the case shown in FIG. 2, the magnetic field generated in the cavity 4 can be increased.

All of the above-mentioned molds are examples in which the permanent magnets 1 sandwiching the yoke 2 are in contact with each other at the non-cavity surface side end in the cavity radial direction, but the present invention is not limited to this case. Instead, as shown in FIG. 5A for a mold for manufacturing a cylindrical magnet having an outer peripheral surface as a working surface,
The contact position of the permanent magnet 1 may be before reaching the outer peripheral end, and in this case as well, the magnetic flux leaking from the yoke 2 is greatly reduced and the magnetic field generated in the cavity 4 is increased as in the case described above. can do. Note that FIG. 5 (b)
Is a cross section taken along line EE ′ of FIG. However,
If the contact position of the permanent magnet 1 is too close to the cavity, the area where the magnetic flux is emitted from the magnet to the ferromagnetic body is rather reduced. Therefore, the contact length h of the permanent magnet 1 is 80 times the mold thickness H.
% Or less is desirable.

In the present invention, the width L of the yoke sandwiched by the permanent magnets at the cavity side end surface is preferably 20% or more of the perimeter of the magnetic pole obtained by dividing the cavity perimeter by the number of magnetic poles. If the width of the yoke on the cavity side end face is less than 20% of the circumference of each magnetic pole, the magnetization of the ferromagnetic material that constitutes the yoke reaches saturation, and the magnetic flux easily leaks in the axial direction of the cylinder. This is because there is a large possibility that the magnetic flux cannot be effectively guided into the cavity. However, when the yoke width L exceeds 90%, the magnet width on the cavity side becomes thin and the permeance becomes small, so that the magnetic field generated in the cavity also becomes small. Therefore, the yoke width L is preferably 90% or less. The optimum range of the yoke width L is 50 to 80% of the circumference of each magnetic pole, and in this case, the magnetic field in the cavity can be effectively increased without leakage of magnetic flux from the ferromagnetic material. You can

Further, in the present invention, as shown in FIGS. 6A and 6B, a permanent magnet having the same pole as the magnetic pole of the orientation permanent magnet 1 adjacent to the yoke 2 is provided on the end face of the yoke 2 in the cylindrical axial direction. By disposing 9, the total amount of magnetic flux in the cavity 4 can be increased. The reason for this is that by disposing the permanent magnet 9 on the end face in the axial direction of the cylinder, the leakage of the magnetic flux from the end face in the axial direction of the cylinder is completely blocked, and the entire magnetic flux can be effectively guided into the cavity 4. is there. 7 (a) and 7 (b) are cross-sectional views of a mold in which the permanent magnet 9 as described above is installed in a mold for manufacturing a cylindrical magnet having an inner peripheral surface as an action surface, and its G-. It is a G'sectional view.

Further, in the present invention, as shown in FIG. 8 (a), the orientation direction of the magnetic powder particles of the orientation permanent magnet 1 is from the cavity direction with the magnet surface in contact with the yoke 2 as a reference line.
It is effective to tilt it by 90 ° or more. This is because such magnetic powder orientation can increase the amount of magnetic flux generated from the permanent magnet 1, thus increasing the magnetic field in the cavity 4, and thus the magnetic field generated from the surface of the obtained magnet. Because it can be further increased. Note that FIG. 8B shows a line H-H ′ in FIG.
FIG. 9 (a) and 9 (b) are cross-sectional views of a mold for manufacturing a cylindrical magnet having an inner peripheral surface as a working surface, in which the permanent magnet 1 is oriented as described above and It is the II 'sectional view.

As the permanent magnet used in the present invention, any of the conventionally known ones can be used, but those having a high magnetic property are particularly preferable in the temperature range of 100 to 250 ° C. which is the working temperature range of the mold, and for example, Sm. Samarium-cobalt based magnets such as ₂ Co ₁₇ and Sm ₁ Co ₅ are particularly advantageous.
As the ferromagnetic material for the yoke, any conventionally known ferromagnetic material can be used, for example, mild steel, carbon steel, die steel and the like can be used. Further, as the non-magnetic material, for example, austenitic stainless steel, copper beryllium alloy, high manganese steel and the like are suitable.

[0016]

[Example] Strontium ferrite powder having an average particle size of 1.5 μm and a green density of 3.35 g / cm ³ : 100 parts by weight,
After adding 0.5 parts by weight of titanate coupling agent and surface-treating it in a Henschel mixer, 90.5 parts by weight of this surface-treated powder, 9.2 parts by weight of nylon 12 resin and 0.3 part by weight of antioxidant: 0.3 parts by weight are again added in the Henschel mixer. Then, the mixture was kneaded and granulated at 240 ° C. by a twin-screw extractor. Using the obtained granulated material as a raw material, a mold according to the present invention and a conventional mold are used, and injection molding is performed.
A multi-pole anisotropic cylindrical magnet having 10 poles in the outer periphery having the shape and size shown in 10 was manufactured. The injection molding was performed using an injection molding machine with a mold clamping force of 35 tons under the conditions of a molding temperature of 300 ° C., a mold temperature of 80 ° C. and an injection pressure of 1.8 tons / cm ² .

Example 1 A multipole anisotropic cylindrical magnet was obtained by using a mold as shown in FIG. In this case, the permanent magnet is an Sm-Co magnet and the ferromagnetic yoke is an SKD-
61, high Mn steel was used as the non-magnetic material. The width L of the end face of the yoke sandwiched by the permanent magnets on the cavity side was set to 20% of the circumferential length per magnetic pole. The surface magnetic field of the obtained magnet is 1560.
G, and the maximum number of cavities that can be taken in the mold, that is, the maximum number of cavities, was eight.

(Embodiment 2) A multi-pole anisotropic cylinder is prepared by using a mold having the same structure as that of Embodiment 1 except that the width L of the end face of the ferromagnetic material on the cavity side is 50% of the circumference of each magnetic pole. I got a magnet. The surface magnetic field of the obtained magnet was 1600 G, and the maximum number of magnets was 8, which was the same as in Example 1.

(Embodiment 3) Next, as shown in FIG.
A multi-pole anisotropic cylindrical magnet was obtained using the mold. Here, the width L of the cavity-side end surface of the yoke is 50% of the circumferential length per magnetic pole.
The contact length h of the permanent magnet was 20% of the die thickness H. The materials of the permanent magnet, the yoke and the non-magnetic material are the same as in the first embodiment. The surface magnetic field of the obtained magnet was 1580 G, and the maximum number of magnets was 8.

(Embodiment 4) Next, as shown in FIG.
A multi-pole anisotropic cylindrical magnet was obtained using the mold. Here, the width L of the cavity-side end surface of the yoke is 50% of the circumferential length per magnetic pole.
The materials of the permanent magnet, the yoke and the non-magnetic material are the same as those in the first embodiment. The surface magnetic field of the obtained magnet is 1620 G
And the maximum number was 8.

Example 5 A multipole anisotropic cylindrical magnet was obtained by using a mold as shown in FIG. The width L of the end face of the yoke on the cavity side is 50% of the circumference of each magnetic pole, and the orientation direction of the magnetic powder particles of the permanent magnet is 110 ° from the cavity direction with the magnet surface in contact with the yoke as the reference line.
I was leaning. The materials of the permanent magnet, the yoke and the non-magnetic material are the same as in the first embodiment. The surface magnetic field of the obtained magnet is 16
It was 40 G and the maximum number was 8.

(Comparative Example 1) A multipolar anisotropic cylinder was prepared by using a mold having the same structure as in Example 1 except that the width L of the end surface of the ferromagnetic material on the cavity side was set to 15% of the circumference per magnetic pole. I got a magnet. Although the maximum number of magnets was 8, the surface magnetic field of the obtained magnet was only 1430 G.

Comparative Example 2 A multipole anisotropic cylindrical magnet was obtained using the conventional die shown in FIG. The width L of the cavity-side end surface of the yoke sandwiched by the permanent magnets is 50% of the circumferential length per magnetic pole. Although the maximum number of magnets was 8, the surface magnetic field of the obtained magnet was only 1380 G.

(Comparative Example 3) A multi-pole anisotropic cylindrical magnet was obtained using the conventional die shown in FIG. The width L of the cavity-side end surface of the yoke sandwiched by the permanent magnets is 50% of the circumference of each magnetic pole. The surface magnetic field of the obtained magnet was 1530 G, but the maximum number of magnets was only 4.

(Comparative Example 4) A multi-pole anisotropic cylindrical magnet was obtained using the conventional die shown in FIG. The width L of the cavity-side end surface of the yoke sandwiched by the permanent magnets is 50% of the circumferential length per magnetic pole. The surface magnetic field of the obtained magnet was 1570 G, but the maximum number of magnets was only 4.

The above results are summarized in Table 1.

[Table 1] As is clear from the table, when the mold according to the present invention was used, all the obtained magnets had a high surface magnetic field and the maximum number of magnets was 8, which was excellent in multi-cavity production. On the other hand, Comparative Examples 1 and 2 each have a low surface magnetic field of the obtained magnet, and Comparative Examples 3 and 4 each have a moderate value of the surface magnetic field of the magnet. There wasn't. In the examples described above, the case of producing a ferrite magnet was mainly shown, but it was confirmed that good results can be obtained even when the present invention is applied to the production of rare earth magnets and other magnets. ing.

[0027]

Thus, according to the mold of the present invention, a large number of multipolar anisotropic magnets having a particularly large surface magnetic field can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an injection-molding die according to the present invention, which is suitable for manufacturing a cylindrical magnet having an outer peripheral surface as a working surface.

2A is a sectional view taken along the line AA ′ in FIG.
(B) is the BB 'sectional view.

FIG. 3 is a vertical cross-sectional view of an injection molding die according to the present invention, which is suitable for manufacturing a cylindrical magnet having an inner peripheral surface as a working surface.

FIG. 4A is a sectional view taken along line CC ′ of FIG.
(B) is the DD 'sectional drawing.

FIG. 5A is a cross-sectional view of another mold according to the present invention, which is suitable for manufacturing a cylindrical magnet having an outer peripheral surface as a working surface. (B) is the EE 'sectional view.

FIG. 6 (a) is a diagram showing the production of a cylindrical magnet having an outer peripheral surface as a working surface, in which a permanent magnet having the same pole as the magnetic pole of an orientation permanent magnet adjacent to the yoke is disposed on the end surface of the yoke in the cylindrical axial direction. 1 is a cross-sectional view of a mold according to the present invention, which is suitable for use in (B)
FIG. 13 is a sectional view taken along the line FF ′.

FIG. 7A shows a cylindrical magnet having an inner peripheral surface as a working surface, in which a permanent magnet having the same pole as the magnetic pole of an orientation permanent magnet adjacent to the yoke is disposed on the end surface of the yoke in the cylindrical axial direction. FIG. 6 is a cross-sectional view of a mold according to the present invention suitable for use in manufacturing. (B)
[Fig. 6] is a sectional view taken along line GG '.

FIG. 8 (a) is a cross-sectional view of a mold according to the present invention, which is suitable for use in the manufacture of a cylindrical magnet having an outer peripheral surface as an active surface on which permanent magnets for orientation in which the orientation direction of magnetic powder particles is devised are mounted. It is a figure. (B) is the HH 'sectional drawing.

FIG. 9 (a) is a cross-section of a mold according to the present invention, which is suitable for use in the manufacture of a cylindrical magnet having an inner peripheral surface as an active surface on which permanent magnets for orientation in which the orientation of magnetic powder particles is devised is mounted. It is a side view. (B) is the II 'sectional drawing.

FIG. 10 is a diagram showing the dimensions and shape of the cylindrical magnet manufactured in the example.

11A is a plan view of a conventional mold used in Comparative Example 2. FIG. (B) is the KK 'sectional drawing.

12A is a plan view of a conventional mold used in Comparative Example 3. FIG. (B) is the LL 'sectional view.

13A is a plan view of a conventional mold used in Comparative Example 4. FIG. (B) is the MM 'sectional view.

[Explanation of symbols]

 1 Orientation permanent magnet 2 Yoke 3 Non-magnetic material 4 Cavity 5 Runner 6 Sprue 7 Nozzle touch 8 Ejection pin 9 Permanent magnet

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaharu Abe 1 Kawasaki-cho, Chiba-shi, Chiba Inside the Technical Research Division, Kawasaki Steel Co., Ltd. (72) Inventor Satoshi Nakatsuka 2-3 2-3 Uchisaiwai-cho, Chiyoda-ku, Tokyo Tani Kokusai Building Kawasaki Steel Co., Ltd. Tokyo Head Office (72) Inventor Koichiro Sawa 3-14-1, Hiyoshi, Kohoku Ward, Yokohama City, Kanagawa Prefecture Keio University Faculty of Engineering

Claims (4)

[Claims] 1. An even number of permanent magnets for orientation are provided along the inner or outer peripheral surface of a cavity for manufacturing a multi-pole anisotropic cylindrical magnet having an inner or outer peripheral surface as a working surface. In a die assembled in an annular shape so that the magnetic poles facing each other through the yoke of the same are the same pole, the width of the yoke gradually narrows from the cavity side to the non-cavity side, and the yokes are adjacent to each other at least at the non-cavity side end portion. A multi-pole structure, in which the orientation permanent magnets are in contact with each other, and the width of the cavity-side end surface of the yoke is 20% or more of the perimeter of the magnetic pole obtained by dividing the perimeter of the cavity by the number of magnetic poles. Mold for manufacturing anisotropic magnets. 2. The gold for producing a multipolar anisotropic magnet according to claim 1, wherein the width of the end face of the yoke on the cavity side is 50% to 80% of the perimeter of the magnetic pole obtained by dividing the perimeter of the cavity by the number of magnetic poles. Type. 3. The multipole anisotropic magnet manufacturing method according to claim 1, wherein a magnet having the same pole as the magnetic pole of the permanent magnet for orientation adjacent to the yoke is arranged on the end surface of the yoke in the cylindrical axial direction. Mold. 4. The gold for producing a multi-pole anisotropic magnet according to claim 1, wherein the orientation direction of the magnetic powder particles of the orientation permanent magnet is inclined by 90 ° or more from the cavity direction with respect to the magnet surface in contact with the yoke. Type.