JPH05234745A - Anisotropic long magnet - Google Patents

Abstract

PURPOSE:To obtain a high surface magnetic field on an operating surface by orientation axes of easy magnetization of magnetic powder particles in a section in a direction from one domain in an operating domain to another domain in the operating domain through an interior of a magnet. CONSTITUTION:A long magnet 1 has a rectangular cross section, and one of its long sides 2 is used as an operating domain. Axes of easy magnetization of magnetic powder particles are oriented in a direction from one of domains 3a and 3b split from the operating domain again to the other domain in the same operating domain through an interior of the magnet, and the operating domain is continued longitudinally. Thus, the surface magnetic field of the operating surface of the long magnet can be remarkably improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anisotropic long magnet, and more particularly to improving the surface magnetic field on the working surface of the magnet. The present invention is particularly advantageously suited for use in applications where the magnet working surface is elongated and elongated and is required, for example, applications such as a magnet for attracting and fixing to a long bulletin board.

[0002]

2. Description of the Related Art Heretofore, rare earth-based or ferrite-based sintered magnets or synthetic resin magnets have been mainly used as magnets for this type of application. Among the above magnets, those having a strong surface magnetic field and an excellent attracting force are rare earth type sintered magnets and synthetic resin magnets. Compared with these magnets, ferrite type sintered magnets have some performance and ferrite type magnets. Synthetic resin magnets are considerably inferior in performance and have been used according to their respective applications. In other words, high-cost rare-earth magnets have been used for high-grade applications, and low-cost ferrite-based magnets have been used for low-grade purposes.In any case, the magnetic particles are oriented in the isotropic or thickness direction, and the magnetic properties are the raw materials used. It was determined only by the good and bad of. Among them, ferrite synthetic resin magnets have the advantage that they can be easily molded even if they have complicated shapes, and they are lightweight and can be integrally molded, but their use was naturally limited due to the low surface magnetic field of the magnet. ..

[0003]

DISCLOSURE OF THE INVENTION The present invention advantageously solves the above-mentioned problems and is a novel magnetic powder particle capable of obtaining a high surface magnetic field on the working surface even when a ferrite magnetic powder is used. The purpose is to propose a long magnet having an oriented structure.

[0004]

First, the process of clarifying the present invention will be described. The inventors of the present invention act from the non-acting surface shown in FIG. 2 on the conventional magnet having the magnetic powder orientation (hereinafter referred to as axial orientation) along the plate thickness direction shown in FIGS. 1A and 1B. As a result of intensive studies to clarify the reason why a magnet focused and oriented toward the surface (hereinafter referred to as “focused orientation”) is superior in magnetic characteristics, the reason is that when magnets are attracted, they do not work. We came to think that the number of magnetic lines of force wasted from the surface and the length of the magnetic path may be the reason. Therefore, in order to reduce the number of magnetic lines of force that are unnecessarily radiated at the time of adsorption and the magnetic path length thereof, radiation of magnetic lines of force from surfaces other than the working surface is eliminated, that is, magnetic flux leakage from surfaces other than the working surface is eliminated. As a result, an unexpected result was obtained regarding the improvement of magnetic properties.

The present invention is based on the above findings. That is, the present invention is a long magnet in which a working region formed in one or a plurality of regions of a contour line in a cross section (hereinafter, simply referred to as a cross section) crossing the longitudinal direction of the long magnet is continuous in the longitudinal direction. The easy axis of magnetization of the magnetic particles,
The anisotropic long magnet is oriented so as to return from one area in the working area to the other area in the working area through the inside of the magnet. In the present invention, by adopting a flexible synthetic resin material as the magnet material, the application can be further expanded.

The present invention can be applied to both synthetic resin magnets and sintered magnets. For example, as the magnetic powder in the synthetic resin magnet and the sintered magnet, any conventionally known magnetic powder such as ferrite magnetic powder, alnico magnetic powder, and rare earth magnetic powder such as samarium-cobalt magnetic powder or neodymium-iron-boron magnetic magnet can be used. The average particle size is preferably about 1.5 μm for ferrite and about 5 to 50 μm for others.

As the synthetic resin, any of the conventionally known ones can be used, and typical examples thereof are as follows. Polyamide-based synthetic resins such as polyamide-6 and polyamide-12. A homopolymer or copolymer vinyl-based synthetic resin such as polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polymethylmethacrylate, polystyrene, polyethylene and polypropylene. Synthetic resins such as polyurethane, silicone, polycarbonate, PBT, PET, polyetheretherketone, PPS, chlorinated polyethylene and hypalon. Rubbers such as propylene, neoprene, styrene butadiene and acrylonitrile butadiene. Epoxy resin. Phenolic synthetic resin. Furthermore, the mixing ratio of magnetic powder and synthetic resin that is a binder is, by volume ratio, magnetic powder: 40-68 for injection molding, synthetic resin: about 60-32, and 90-95: 10- for compression molding.
It is desirable to set it to about 5.

In addition to the above, it goes without saying that appropriate amounts of conventionally used plasticizers, antioxidants, surface treatment agents and the like can be used, and especially when a plasticizer imparts flexibility. Examples of such plasticizers include phthalate ester-based plasticizers such as dioctyl phthalate (DOP) and dibutazyl phthalate (DBP), adipic acid-based plasticizers such as dioctyl adipate (DOA), and polyester-based plasticizers. Polymeric plasticizers typified by and the like are preferable.

[0009]

The present invention will be described in detail below. Figure 3
A typical long magnet according to the present invention is shown in (a). This long magnet 1 has a rectangular cross section and has one of its long sides 2 as an operating region, and the easy axis of magnetization of the magnetic powder particles is divided from one of the regions 3a and 3b which divide this operating region into two. The magnet is oriented so as to return to the other area in the same working area through the inside of the magnet, and this working area is connected in the longitudinal direction. Further, as shown in FIG. 2B, which shows the radiation state of the magnetic force lines when the long magnet 1 is attracted, a closed circuit can be formed with almost no leakage of the magnetic force lines from the surface other than the working surface, and therefore, The magnetic flux density is far superior to that of the conventional axial type or focused orientation type magnet.

Further, as shown in FIG. 4 in which both short sides 4 of the rectangular cross section are used as the working area, a plurality of surfaces (or regions) can be set as the working area.

In the above example, the case where the cross section of the long magnet is rectangular has been mainly described, but the shape of the magnet is not limited to this case, and as shown in FIGS. 5 (a) to 5 (i). , A trapezoid, a triangle, a polygon, a circle, or a semicircle may be various cross-sectional shapes. The point is that the orientation direction of the magnetic powder particles is in one or more regions of the contour line in the cross section of the long magnet. It suffices to form an operating region that returns and the operating region is continuous or intermittent in the longitudinal direction.

Now, according to the present invention, by controlling the orientation direction of the easy axis of magnetization of magnetic powder particles in a long magnet,
It is intended to improve the surface magnetic field on the surface where the magnet is used. Therefore, FIG. 6 schematically shows a molding die having a magnetic circuit suitable for realizing the magnetic powder orientation according to the present invention. In the figure, reference numeral 5 is a cavity provided in the molding die, 6 is a main pole, 7 is a counter pole, and 8 is a return yoke of the magnetic circuit.

Now, in the cavity 5, for example, a synthetic resin magnet in which magnetic powder and synthetic resin are mixed at a predetermined ratio is loaded,
Moreover, when a magnetic field is applied while pushing out the case of a synthetic resin magnet as shown in FIG. 7, magnetic force lines 9 are generated in the direction shown by the arrow in the figure, and the easy axis of magnetization of the magnetic powder particles is oriented along the magnetic force lines 9. Will be done. Here, the leakage of the lines of magnetic force is only on the working surface, and there is almost no leakage from surfaces other than the working surface.

By the way, the magnetic pole 4 of the magnetic field orientation molding die,
Ferromagnetic materials used for the opposing magnetic pole 5 and the return yoke include carbon steel such as S55C, S50C, and S40C, SKD.
Die steels such as 11, SKD61, etc., other materials such as pamenjour, pure iron, etc. can be used, but it is more advantageous to apply a surface hardening treatment to improve wear resistance. As the non-magnetic material filling the magnetic pole, stainless steel, copper-beryllium alloy, high-manganese steel, bronze, brass and non-magnetic cemented steel N-7 are suitable, and wear resistance is also required as required. It is advantageous to apply a surface hardening treatment for improvement.

[0015]

EXAMPLE A molding die having a magnetic circuit shown in FIG. 6 and a molding die having a magnetic circuit having a focusing orientation shown in FIG. 2 (not shown) were used, and the shape shown in FIG. 3 was used. A long magnet having dimensions of width: 8 mm, thickness: 4 mm and length: 150 mm was molded under the conditions shown in Tables 1 to 3 below. In the experiment using the magnetic powder B shown below, a giant magnetic field having a pulse shape was applied in advance, and the magnetic moments of the magnetic powder were aligned to perform magnetic field orientation molding.

[0016]

[Table 1] Raw materials / Magnetic powder particles Magnetic powder A: Ferrite magnetic powder (magnetoplumbite-based strontium-based ferrite with an average particle size of 1.5 μm) Magnetic powder B: Samarium-cobalt magnetic powder (2-17 system; average particle size 15 μm) -Synthetic resin: Chlorinated polyethylene-Plasticizer: DOP (Dioctyl phthalate) -Others: Polyethylene wax TTS (Isopropyltriisostearoyl titanate)

[0017]

[Table 2] Composition / Composition A (Plamag composition) Magnetic powder A: 61.5 vol% Chlorinated polyethylene: 12 vol% DOP: 25.5 vol% Polyethylene wax: 0.5 vol% TTS: 0.5 vol%・ Compound B (Sintering mix) Magnetic powder: 50 wt% Water: 50 wt%

[0018]

[Table 3] Molding conditions / extrusion molding conditions Pellet composition used: Compound A Extrusion cylinder temperature: 160 ° C Temperature near discharge port: 160 ° C Discharge speed: 2m / min Extruder: Full flight type Cylinder diameter 70mm (cylinder length) / (Inner diameter) = 22 Compression ratio 3 Excitation coil magnetomotive force: 10000 ampere turns Land part magnetic field applied width: 70mm ・ Compression molding conditions Raw material: Compound B Molding method: Injection method Excitation direction: Compression direction Excitation coil magnetomotive force: 10000 ampere turns Molding temperature: 20 ° C Firing temperature: 1250 ° C

Table 4 shows the results of examining the surface magnetic field of the thus obtained long magnet after magnetization. A Hall element (70 μm square gallium arsenide) was used for the measurement of the surface magnetic field.

[0020]

[Table 4]

As is clear from Table 4, it was confirmed that the long magnets obtained according to the present invention can significantly improve the surface magnetic field on the working surface as compared with those obtained according to the conventional method. ..

[0022]

As described above, according to the present invention, the surface magnetic field on the working surface of the long magnet can be remarkably improved, which greatly contributes to the expansion of the applicable range of this kind of magnet.

[Brief description of drawings]

FIG. 1A is a schematic view of a conventional axial long magnet. (B) is a magnetic force diagram of a conventional axial magnet.

FIG. 2 is a diagram showing a magnetic field line distribution of a conventional focusing orientation type magnet.

FIG. 3A is a schematic diagram of a closed circuit type magnet having a long side as a working region according to the present invention. (B) is a diagram showing a magnetic field line distribution of a closed circuit type magnet having a long side as a working region according to the present invention.

FIG. 4 is a schematic diagram of a closed circuit type magnet having a short side as a working region according to the present invention.

FIG. 5 is a schematic view showing an end face of a long magnet.

FIG. 6 is a schematic view of a molding die suitable for use in manufacturing the closed circuit magnet of the present invention.

FIG. 7 is a schematic view showing the procedure of extrusion molding.

[Explanation of symbols]

 1 Long magnet 2 Long side 3a Area 3b Area 4 Short side 5 Cavity 6 Main pole 7 Opposing pole 8 Back yoke 9 Magnetic field lines

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Kadai 1 Kawasaki-cho, Chiba City, Chiba Prefecture Kawasaki Steel Co., Ltd. Technical Research Headquarters (72) Inventor Takahiro Kikuchi 1 Kawasaki-machi, Chiba City Chiba Prefecture Kawasaki Steel Co., Ltd. (72) Inventor Akira Yasuda 2-3-2 Uchisaiwaicho, Chiyoda-ku, Tokyo Kawasaki Steel Co., Ltd. Tokyo head office

Claims (2)

[Claims] 1. A long magnet in which an active region formed in one or a plurality of regions of a contour line in a cross section crossing the longitudinal direction of the long magnet is connected in the longitudinal direction, and an easy axis of magnetization of magnetic powder particles in the cross section is formed. An anisotropic long magnet oriented in a direction of returning from one area in the working area to the other area in the working area through the inside of the magnet. 2. The anisotropic long magnet according to claim 1, wherein the magnet material is a flexible synthetic resin material.