JPH0797529B2 - Focused orientation type disk magnet and magnetic field orientation molding machine - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focusing orientation type disc magnet suitable for use as a permanent magnet for a flat type motor and a magnetic field orientation molding machine suitable for producing the magnet, and particularly to the action of the disc magnet. This is intended to improve the surface magnetic field on the surface.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 6, a disk-shaped permanent magnet 101 magnetized in the thickness direction is used for a flat type motor such as a floppy disk or hard disk spindle motor or a VTR capstan motor. However, since the area of the stator coil 102 is smaller than the area of the disk-shaped magnet 101, that is, the effective working area of the magnet for the stator coil is small, it cannot be said that the magnetized surface is effectively used. It was Therefore, the obtained torque was not enough for the size of the magnet used. In the figure, reference numeral 103 is an upper case, 104 is a back yoke, 105 is a bush, 106 is a shaft, and 107 is a lower case.

[0003]

DISCLOSURE OF THE INVENTION The present invention advantageously solves the above-mentioned problems, and the magnetic flux can be effectively focused only on the substantial working surface of the disk-shaped magnet. SUMMARY OF THE INVENTION It is an object of the present invention to propose a focusing orientation type disc magnet capable of improving the surface magnetic field in (1) and further improving torque when used as a flat type motor together with a magnetic field orientation molding machine suitable for manufacturing such a magnet.

That is, according to the present invention, in a disk-shaped magnet having one of the front and back surfaces as the working surface, the orientation direction of the magnetic powder particles in the thickness direction of the disk-shaped magnet is the central ring area of the working surface side track of the magnet. It is a focusing orientation type disk-shaped magnet (first invention).

The present invention is also a magnetic field orientation molding machine for applying a magnetic field to a magnet material introduced into a disk-shaped cavity of a molding die to orient magnetic particles in the material in a thickness direction.
A magnetic field obtained by reducing the area of the magnetic field application surface of either one of the main pole and the counter pole, which are also arranged in a disk-like manner so as to face each other across the cavity, with respect to the other, around the central ring of the disk track. It is an orientation molding machine (2nd invention).

[0006]

In the present invention, the magnetic circuit of the molding die is modified to control the orientation direction of the magnetic particles in the magnet material, thereby improving the surface magnetic field on the substantially working surface of the disk-shaped magnet. Specifically, the area of the magnetic field application surface of one of the magnetic poles of the main pole and the counter pole, which are also in the shape of a disk and are arranged so as to face each other with the disk-shaped cavity sandwiched between them, and the center ring of the disk track is By decreasing as the center, the magnetic field lines in the molding die cavity are focused on the central ring region of the working surface side track. Thus, with respect to the magnet material charged in the cavity, the orientation direction of the magnetic powder can be aligned with the direction of the magnetic force lines, that is, it can be focused on the central ring region of the track on the working surface side of the magnet. The surface magnetic field at the substantial working surface of the magnet can be significantly improved.

1A and 1B respectively show a disk-shaped magnet in which magnetic powder particles are oriented according to the present invention and a disk-shaped magnet having a particle orientation according to a conventional method in comparison. As is clear from the figure, in the conventional magnet shown in FIG. 1 (b), there is a useless magnetic flux, whereas in the magnet of the present invention shown in FIG. 1 (a), all the magnetic flux substantially acts. It is focused on the surface and is effectively used, so that a higher surface magnetic field is obtained.

Here, in FIG. 1, the orientation angle of the magnetic powder particles indicated by α is preferably 10 to 70 °, and more preferably 60 to 20 °. When the orientation angle α is smaller than 10 °, the effect of improving the surface magnetic field is poor, while when it is larger than 70 °, the effective surface on which the surface magnetic field appears is significantly narrowed, and it decreases depending on the intrinsic coercive force of the magnet. This is because it may be magnetized.

Both synthetic resin magnets and sintered magnets can be used as the disk-shaped magnet of the present invention. 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 1.5μm, and the compression density is 3.20.
The above is preferable.

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. Vinyl-based synthetic resins such as polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polymethylmethacrylate, polystyrene, polyethylene and polypropylene which are homopolymerized or copolymerized. Synthetic resins such as polyurethane, silicone, polycarbonate, PBT, PET, polyetheretherketone, chlorinated polyethylene and hypalon. Rubbers such as propylene, neoprene, styrene butadiene and acrylonitrile butadiene. Epoxy resin. Phenolic synthetic resin. Furthermore, the mixing ratio of the magnetic powder and the synthetic resin as the binder is:
In contrast to 90, it is desirable that the synthetic resin is about 10. In addition, it goes without saying that appropriate amounts of conventionally used plasticizers, antioxidizing agents, surface treatment agents and the like can be used according to the purpose.

Next, the magnetic field orientation molding machine according to the present invention will be described. FIG. 2 schematically shows a preferred example of a magnetic field orientation molding machine having an injection molding die according to the present invention, in which numeral 1 is a cavity provided in a die 2, 3 is a main pole, 4 is a counter electrode, In this example, the area of the magnetic field application surface of the counter electrode 4 is made smaller than that of the main pole 3. Further, 5 is a fixed platen, 6 is a movable platen, 7 is a nozzle touch, 8 is a sprue runner, 9 is a protruding pin, 10 is a protruding plate, 11 is a cavity plate, and 12 is a sprue bush.

In the figure, a ferromagnetic material is used for the main pole 3, the counter electrode 4, the fixed plate 5, the movable plate 6, the protruding pin 9, and the protruding plate 10, while the die 2, the cavity plate 11 and the sprue bush 12 are used. A non-magnetic material is used. Here, as the ferromagnetic material, S55C, S50
Carbon steels such as C and S40C, die steels such as SKD11 and SKD61, and other materials such as pamenjour and pure iron can be used, but it is more advantageous to apply a surface hardening treatment to improve wear resistance. On the other hand, as the non-magnetic material, stainless steel, copper-beryllium alloy, high-manganese steel, bronze, brass, non-magnetic super steel N-7, etc. are advantageously applicable, and surface hardening for improving wear resistance is also applied to these if necessary. It is advantageous to apply the treatment.

As shown in FIG. 2, when the synthetic resin magnet material introduced into the disk-shaped cavity 1 by injection molding is in a softened state and a magnetic field is applied to the magnet material, lines of magnetic force are generated in the disk. The central axis of the main pole track passes through the central cavity of the main pole side track so that the axis of easy magnetization of the magnetic particles in the magnet material is in the central ring zone of the main pole side track. It is oriented so as to focus, and thus a focusing type disc magnet as shown in FIG. 3 is obtained.

From the surface of the mold magnetic circuit, on the narrow area side where the magnetic flux is to be narrowed, the width of the magnetic pole is made narrower than the cavity width around the center ring of the side track, while the opposite wide area side is formed. On the magnetic field application surface of the magnetic pole, it is important that the width of the magnetic pole be equal to or wider than the cavity width.

It is particularly preferable that the slope of the disk-shaped cavity be equal to the direction of the lines of magnetic force generated in the cavity. This is because, if the slope gradient is as described above, the magnetic leakage from the magnet slope is the smallest when a magnet product is used, and the surface magnetic field on the working surface can be made the strongest. The so-called donut shape of hollowing is preferable in consideration of the case of incorporating it into the motor thereafter, but in the present invention, such hollowing is not always an essential requirement.

The case where an injection molding die is mainly used as the molding die has been described above. However, if a required portion of the magnetic circuit die is changed to another molding die, a compression molding die is used. You can also FIG. 4 schematically shows a preferred example of the magnetic field orientation molding machine according to the present invention, which incorporates a compression molding die. In the figure, numeral 13 is a mold frame (magnetic material) that also serves as the yoke of the magnetic circuit, 14 is an upper punch plate bush (magnetic material), 15 is an upper punch plate (magnetic material), and 16 is a die. Control cylinder, 17 die control rod, 18 upper punch (magnetic material), 19 lower punch (magnetic material), 20 die (non-magnetic material), 21 die plate (non-magnetic material), 22 upper coil , 23 is the lower coil,
24 is a core (non-magnetic material), 25 is a core plate (non-magnetic material), and 26 is a molded body.

[0017]

EXAMPLE A magnetic field orientation molding machine equipped with an injection molding mold (mold A) as shown in FIG. 2 and a compression molding mold (mold B) as shown in FIG. A disk-shaped magnet having the dimensions shown in was molded under the following conditions. 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 (Sm ₂ Co ₁₇ system; average particle size 10 μm) ・ Synthetic resin: polyamide 12 ・ Plastic Agent: TTS (isopropyl triisostearoyl titanate)

The blending and mixing A (plastic magnet formulation) magnetic powder: 66 vol% polyamide 12:33 vol% TTS: 1 vol% · formulation B (sintered formulation) magnetic powder: 40 wt% water: 60 wt%

Molding Conditions / Injection Molding Conditions Pellet mix used: Mixture A Injection cylinder temperature: 300 ℃ Mold temperature: 100 ℃ Injection pressure: 1800 kg / cm ² Excitation time: 5 s: Always (polar anisotropic type using permanent magnet) ) Cooling time: 15 seconds Injection cycle: 30 seconds ・ Compression molding conditions Raw material: Compound B Draining method: Injection method Excitation method: Vertical magnetic field molding Molding temperature: 20 ℃ Firing temperature: 1250 ℃

Table 1 shows the results of examining the surface magnetic field and the starting torque (motor characteristics) of the thus obtained disk-shaped magnet after magnetization. The evaluation conditions of the motor characteristics are as follows.

Magnet outer diameter: 60 mm Inner diameter: 20 mm Thickness: 4 mm Magnetization: 8 poles-Coil phase: 3-phase 6-coil winding number: 140 turns / coil resistance: 15 ohms / coil-Driving method 3-phase bipolar Voltage: 12V current : 400 mA (200 mA / phase)

[0022]

[Table 1]

As is clear from the table, by using the magnetic field orientation molding machine according to the present invention, the magnetic powder in the disk-shaped magnet is focused on the central ring region of the track on the working surface side, so that the surface magnetic field on the working surface is greatly increased. Can be improved and excellent torque characteristics are obtained.

[0024]

As described above, according to the present invention, the magnetic particles in the disk-shaped magnet material can be effectively oriented in the central ring region of the track on the working surface side, and by extension, the surface on the working surface of the permanent magnet after magnetization. The magnetic field can be remarkably improved as compared with the conventional one.

[Brief description of drawings]

FIG. 1 is a diagram showing a comparison of magnetic powder particle orientations of disc-shaped magnets manufactured according to the present invention and a conventional method.

FIG. 2 is a schematic view of a magnetic field orientation molding machine provided with an injection molding die according to the present invention.

FIG. 3 is a diagram showing a magnetic force line direction of magnetic powder particles after magnetization of a focusing type disc magnet obtained according to the present invention.

FIG. 4 is a schematic view of a magnetic field orientation molding machine equipped with a compression molding die according to the present invention.

FIG. 5 is a diagram showing the dimensions and shape of the disk-shaped magnet manufactured in the example.

FIG. 6 is an exploded view of a flat type motor.

[Explanation of symbols]

 1 Cavity 2 Die 3 Main pole 4 Counter electrode 5 Fixed plate 6 Moving plate 7 Nozzle touch 8 Sprue runner 9 Ejection pin 10 Ejection plate 11 Cavity plate 12 Sprue bush 13 Mold frame 14 Upper punch plate bush 15 Upper punch plate 16 Die control cylinder 17 Die Control Rod 18 Upper Punch 19 Lower Punch 20 Die 21 Die Plate 22 Upper Coil 23 Lower Coil 24 Core 25 Core Plate 26 Molded Body 101 Permanent Magnet 102 Stator Coil 103 Upper Case 104 Back Yoke 105 Bushing 106 Shaft 106 Lower Case

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H01F 1/113 41/02 G H01F 1/04 B (72) Inventor Akira Yasuda 2-2 Uchisaiwaicho, Chiyoda-ku, Tokyo No. 3 Kawasaki Steel Co., Ltd. Tokyo head office (72) Inventor Koichiro Sawa 3-14-1, Hiyoshi, Kohoku Ward, Yokohama City, Kanagawa Prefecture Keio University (72) Inventor Isamu Oyama 1 Kawasaki Town, Chiba City, Chiba Prefecture Kawatetsu Techno Search Co., Ltd.

Claims (2)

[Claims] 1. In a disk-shaped magnet having one of the front and back surfaces as a working surface, the orientation direction of magnetic powder particles in the thickness direction of the disk-shaped magnet is focused on the central ring region of the working surface side track of the magnet. Focused orientation type disc magnet. 2. A magnetic field orientation molding machine for applying a magnetic field to a magnet material introduced into a disk-shaped cavity of a molding die to orient magnetic particles in the material in a thickness direction, the magnet particles being opposed to each other across the cavity. The magnetic field orientation molding machine is characterized in that the area of the magnetic field application surface of one of the magnetic poles of the main pole and the counter pole, which are also disk-shaped, is reduced with respect to that of the other, centering on the central ring of the disk track.