JPH06349630A - Anisortopical magmet - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the surface magnetic field of the magnet working surface in an anisotropic magnet particularly advantageously suited to a motor magnet or the like. An anisotropic magnet comprising an integrally molded body having front and back surfaces as working surfaces, the magnetic powder having a cross section along the outer surface in the longitudinal direction, which has a working region 3 which is discontinuous in the longitudinal direction of each working surface. The easy axis of magnetization of the particles is oriented on the path from one of the adjacent action areas 3 in the same action surface to the other through the inside of the magnet, and the action areas 3 are arranged in the same manner between the front and back action surfaces.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anisotropic magnet which is particularly well suited for use as a magnet for motors and the like, and particularly to improve the surface magnetic field of the magnet working surface.

[0002]

2. Description of the Related Art Both front and back surfaces of a magnet are used as working surfaces,
N poles and S poles are alternately arranged in the longitudinal direction of each working surface,
Moreover, the polar anisotropic magnets in which the arrangement of the N poles and the S poles is the same between the working surfaces on the front and back sides, that is, the poles on the front and back sides are the same poles are used in linear motors and the like.

In this type of magnet, as shown in FIG. 1, the easy axis of magnetization of magnetic powder particles is oriented in the thickness direction, and a magnet 1 similar to the magnet 1 magnetized to have opposite poles on the front and back sides. Generally, the magnet 1 is adhered with the yoke 2 made of iron or the like interposed therebetween.

Further, as the material of the magnet, a ferrite type or rare earth type sintered magnet or a synthetic resin magnet has been mainly used. Of these, rare earth-based sintered magnets and synthetic resin magnets have a particularly strong surface magnetic field and are excellent in attracting force, while ferrite-based sintered magnets and synthetic resin magnets are inferior in performance to these, depending on their respective applications. Has been used. That is, high-cost rare earth magnets have been used for high-grade applications, and low-cost ferrite-based magnets have been used for low-grade applications.

However, since the magnet having the structure shown in FIG. 1 requires an adhesion process, there is a problem that the cost becomes high regardless of whether the material is a ferrite type material or a rare earth type material. Further, this type of magnet is often used in a state where the thickness of the magnet is smaller than the area of the working surface, that is, the permeance is low, and there is a problem that the magnet is easily demagnetized.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above problems by improving the orientation of the magnetic powder particles of the magnet, thus omitting the step of bonding the magnet and using the magnet in a high permeance state. This is to realize and suppress demagnetization.

[0007]

SUMMARY OF THE INVENTION The present invention is an anisotropic magnet composed of an integrally formed body having front and back surfaces as working surfaces, each of which has a working region which is intermittent in the longitudinal direction of each working surface. The easy axis of magnetization of the magnetic powder particles in the cross section along the outer surface of the direction is oriented on the path from one of the adjacent action areas in the same action surface to the other through the inside of the magnet, and the action areas are arranged on the front and back sides. It is an anisotropic magnet whose surfaces are aligned.

The present invention will be specifically described below. Figure 2
FIG. 3 shows an anisotropic magnet according to the present invention in which both front and back surfaces of a plate-shaped magnet are acting surfaces. As shown in the figure, the action region 3 extending in the width direction of the magnet is intermittently formed in the longitudinal direction, and the action regions 3 are arranged so as to be aligned between the action faces on the front and back sides. By setting the orientation of the magnets to the direction shown by the broken line in the figure, the magnetized magnetism does not emit the magnetic field lines from the surfaces other than the active region, and therefore the surface is significantly superior to conventional magnets. A magnetic field is obtained. The magnetization is performed by arranging N poles and S poles alternately on the same working surface, and arranging the N poles and S poles on the two front and back working surfaces so as to be symmetrical with respect to the thickness center.

Therefore, in the anisotropic magnet according to the present invention shown in FIG. 2, the conventional magnet shown in FIG. 1 requires the step of adhering the magnet and the yoke of iron or the like. Eliminating the bonding process.

Further, as compared with the axial orientation of the conventional magnet shown in FIG. 1, the anisotropic magnet shown in FIG. 2 has a longer magnetic path, so that it can be used with a large permeance and is demagnetized as compared with the conventional magnet. It is difficult, and the surface magnetic field is high even when compared with magnets of the same material.

[0011]

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 powder can be used. The average particle size is about 1.5 μm for ferrite and 5-50 μm for others.
It is preferably about m.

As the synthetic resin, any conventionally known synthetic resin can be used, and typical examples thereof are as follows. Polyamide-based synthetic resins such as polyamide-6 and polyamide-12. Homogeneous or copolymerized synthetic resins such as polyvinyl chloride, vinyl chloride vinyl acetate copolymer, polymethylmethacrylate, polystyrene and polypropylene. Polyurethane, silicone, polycarbonate, PBT, P
Synthetic resins such as ET, polyetherketone, chlorinated polyethylene, and Hypalon. Rubber such as neoprene, styrene butadiene and acrylonitrile butadiene. Epoxy resin. Phenolic synthetic resin.

Further, the compounding ratio of the magnetic powder and the binder synthetic resin is preferably 60 to 70 vol% of the magnetic powder.
In addition, it goes without saying that an appropriate amount of conventionally used plasticizers, antioxidants, surface treatment agents and the like can be used, and plasticizers are particularly effective for imparting flexibility. As the plasticizer, for example, dioctyl phthalate (D
OP), phthalate ester-based plasticizers such as dibutadyl titarate (DBP), adipic acid-based plasticizers such as dioctyl adipate (DOA), or polymer-based plasticizers typified by polyesters can be used.

Next, FIG. 3 illustrates a mold magnetic circuit suitable for magnetic powder orientation according to the present invention. In the figure, numeral 4 is a cavity provided in the magnetic field orientation molding die, 5 is a permanent magnet serving as a magnetomotive force main body, 6 is a ferromagnetic yoke and 7 is a sleeve, and a broken line 8 is a magnetic field line in the cavity 4. Shows. It is also possible to use an exciting coil instead of the permanent magnet and the yoke as each forming magnetic pole.

When a magnet made of a predetermined raw material is inserted into the cavity 4, the magnetic powder particles are oriented along the lines of magnetic force 8, and an anisotropic magnet having a desired magnetic powder orientation as shown in FIG. 2 is obtained. .

Incidentally, a samarium-cobalt type magnet, a neodymium-iron-boron type magnet or the like can be used as the permanent magnet 5 of the magnetic field orientation molding die, and pure iron or vermendur alloy is used as the ferromagnetic yoke 6. Can be used.
Further, the sleeve 7 may be made of either a magnetic material or a non-magnetic material, but non-magnetic steel such as stainless steel is advantageously suitable,
It is desirable to apply a surface hardening treatment to improve wear resistance, if necessary.

In the above example, the case where the magnet has a rectangular shape has been mainly described. However, the shape of the magnet is not limited to this case, and the action surface as shown in FIGS. 4 (a) to 4 (c) has a donut shape. , Various shapes such as arc, polygon, etc.,
The point is that the easy axis of magnetization of the magnetic particles in the cross section along the outer surface in the longitudinal direction (the circumference is regarded as the longitudinal direction in the case of a circular shape) moves from one of the adjacent action areas within the same action surface to the inside of the magnet. It suffices that they are oriented on the path through which they pass.

[0018]

EXAMPLE Using the magnetic field orientation molding die shown in FIG.
The shape is as shown in, and its dimensions are width 20 mm, length 160 mm, and thickness.
An anisotropic magnet having a distance (pitch) of 10 mm and an interval (pitch) of magnetic poles (action regions) was produced under the following conditions.

[0019]

[Table 1] Magnetic circuit device Magnetomotive force generator: Permanent magnet, exciting coil or electromagnet system is adopted. SKD 11 is used for the ferromagnetic yoke. Sleeve is SU
Uses S 304.

[0020]

[Table 2] Raw material Magnetic powder A: Ferrite magnetic powder (magnetoplumbite strontium ferrite with an average particle size of 1.5 μm) Magnetic powder B: 2-17 samarium-cobalt magnetic powder (average particle size
15 μm) Compounding composition A: (Pramag compounding) Magnetic powder 63 vol% Polyamide 12 36 vol% Minosilane A-1100 1 vol% Compounding B: (Sintering compounding) Magnetic powder / water 50/50 wt%

[0021]

[Table 3] Molding method Molding method A: Plamag injection molding conditions Mixing pellets used Compounding A Molding machine Built-in coil type magnetic field orientation injection molding machine Injection cylinder temperature 300 ℃ Mold temperature 100 ℃ Injection pressure 1500kgf / cm ² Cooling time 20 seconds Injection Cycle 60 seconds Molding method B: Sintered magnet manufacturing conditions Slurry used B molding machine Coil-mounted magnetic field orientation compression molding machine Draining method Injection method Molding temperature 20 ℃ Firing temperature 1250 ℃

The magnet thus obtained is magnetized as shown in FIG. 2 and then the surface magnetic field is examined. For the measurement of the surface magnetic field, a Gauss meter (manufactured by TOYO MAGNETIC CO., LTD.) Using a Hall element made of 70 μm square gallium arsenide was used. The demagnetization rate of the magnet is indicated by the rate of decrease of the surface magnetic field after being left for 3 months.

For comparison, a magnet having a width of 20 mm, a length of 10 mm and a thickness of 4 mm, which has the axial orientation shown in FIG. 1, is shown in Table 5.
A magnet was produced and magnetized in the same manner as above except under the conditions shown in (4) above, and a sample was produced by adhering to a pure iron yoke having a width of 20 mm, a length of 150 mm and a thickness of 2 mm, and the surface magnetic field was similarly examined.
The results are also shown in Table 5.

[0024]

[Table 4]

[0025]

[Table 5]

As is clear from Tables 4 and 5, the surface magnetic field was improved and the demagnetization rate of the surface magnetic field was also reduced as compared with those obtained by the conventional method.

[0027]

As described above, according to the present invention, it is possible to obtain a magnet which does not require a bonding step, has a higher surface magnetic field and is less likely to be demagnetized as compared with the prior art, and greatly contributes to the expansion of the application range of this kind of magnet. .

[Brief description of drawings]

FIG. 1 is a schematic view of a conventional magnet.

FIG. 2 is a schematic diagram of a magnet according to the present invention.

FIG. 3 is a schematic view of a magnetic field orientation molding die.

FIG. 4 is a schematic diagram showing the shape of another magnet according to the present invention.

[Explanation of symbols]

 1 Magnet 2 Yoke 3 Working Area 4 Cavity 5 Permanent Magnet 6 Yoke 7 Sleeve 8 Magnetic Field Line

Claims (1)

[Claims] 1. An anisotropic magnet comprising an integrally molded body having front and back surfaces as working surfaces, each of which has a working area which is discontinuous in the longitudinal direction of each working surface, and which has a cross section along an outer side surface in the longitudinal direction. The easy axis of magnetization of the magnetic particles is oriented on the path from one of the adjacent action areas in the same action surface to the other through the inside of the magnet, and the arrangement of the action areas is the same between the front and back action surfaces. Directional magnet.