JP3045882B2 - Focusing composite orientation type disc-shaped 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 composite orientation type disc-shaped magnet suitable for use as a rotor magnet for a small precision motor and a magnetic field orientation molding machine suitable for producing the magnet.

[0002]

2. Description of the Related Art As shown in FIG. 1, a flat precision motor usually has a disc-shaped magnet 101 'for torque generation and a signal-generating magnet 102' for speed control and the like. Many. In the figure, reference numeral 103 denotes a stator coil, 104 denotes a magnetic receiving element, 105 denotes a magnet back yoke, 106 denotes a coil yoke, and 107 denotes a shaft.

The disk-shaped magnet 101 'is magnetized in the thickness direction. However, the area of the stator coil 103 is smaller than the area of the disk-shaped magnet 101', that is, the disk-shaped magnet 101 'with respect to the stator coil 103'. Since the effective working area of the magnet was small, it could not be said that the magnetized surface was effectively used, and it was difficult to say that the obtained torque was sufficient for the size of the magnet used.

[0004] Further, in many cases, an isotropic synthetic resin magnet is used for the signal generating magnet 102 ', and the signal is weak. The idea of catching a signal has been devised. Therefore, in order to perform good reception, the magnetic reception element 104
It is necessary to precisely grind the surface facing the above, which has led to an increase in production cost. In addition, expensive sensitive magnetic receiving element 104
In the case of using the same, the production cost similarly increases.

Further, the torque generating magnet is manufactured separately from the signal generating magnet, and at least one of the magnets is bonded to the rotor by bonding or the like to form a rotor.

The present invention advantageously solves the above-mentioned problems, and there is no waste of magnetic flux for a disc-shaped magnet, the sensitivity of a signal generating magnet can be increased, and the number of manufacturing steps can be reduced by integral molding. It is an object of the present invention to propose a focused composite orientation type disc-shaped magnet which can be greatly reduced together with a magnetic field orientation molding machine suitable for manufacturing such a magnet.

That is, the present invention relates to a disk-shaped magnet having one of the front and back surfaces of a disk as an active surface, wherein the orientation direction of the magnetic powder particles in the thickness direction of the magnet is two concentric circles in the active surface. A converging composite orientation type disc-shaped magnet (first invention), wherein the converging is performed on each of the annular zones, and the total area of the annular zones is smaller than the active surface area.

The present invention also relates to a disk-shaped magnet having one of the front and back surfaces and the outer peripheral surface as an acting surface, wherein the orientation direction of the magnetic powder particles in the thickness direction of the magnet is one of the front and back surfaces of the disk. Focusing on the annular zone in the working surface and the central zone on the outer peripheral surface of the disk, wherein each area of the annular zone and the central zone is smaller than the area of each corresponding working surface. This is an oriented disk magnet (second invention).

Further, the present invention is 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 and orienting magnetic powder in the material in a predetermined direction. The counter electrode and the auxiliary electrode forming the working surface, and the main electrode forming the non-working surface, which are arranged opposite to each other with the cavity interposed therebetween, are arranged.The area of the counter electrode and the auxiliary electrode is made smaller than the area of the main electrode. A magnetic field orientation molding machine (third invention).

[0010]

According to the present invention, the magnetic circuit of the molding die is devised to control the orientation direction of the magnetic powder in the magnet material, thereby improving the surface magnetic field on the substantial working surface of the disc-shaped magnet. It improves the sensitivity of the signal generating magnet.

Specifically, in a magnet having one of the front and rear surfaces of a disk as an operating surface, a main pole disposed on a non-operating surface side is provided in order to provide a function of generating torque and a signal in the operating surface. The ring-shaped counter electrode for torque generation and the auxiliary pole for signal generation are concentrically arranged across the cavity, and the total area of the counter electrode and auxiliary pole is smaller than the area of the main pole. The magnetic flux is focused on the counter and auxiliary poles. In addition, while the torque generating function is provided in one of the working surfaces of the front and back surfaces of the disk, and the signal generating function is provided in the outer peripheral surface of the disk, the area of the counter electrode for torque generation opposite to the main pole is set. The auxiliary pole, which is smaller than the main pole and is the same as the counter electrode, is disposed on the side surface of the cavity, and the magnetic flux is focused from the main pole to the counter electrode and the auxiliary pole, as in the above case.

With respect to the magnet material charged in the cavity, the orientation direction of the magnetic powder is aligned with the direction of the line of magnetic force, that is, the inside of the magnet has two annular zones or annular zones on the working surface side and the outer circumferential surface side. Can be focused on the central band of the magnet, so that the magnetic flux after magnetization can be narrowed in a donut shape, and as a result, the surface magnetic field on the substantial working surface of the disk magnet can be significantly improved.
On the other hand, the vicinity of the working surface edge or the outer peripheral surface can be similarly focused in a donut shape or the central band of the outer peripheral surface, so that the receiving sensitivity can be significantly improved.

FIGS. 2 to 4 show a disk-shaped magnet in which magnetic powder particles are oriented according to the present invention. As is apparent from FIG. 5, the disc-shaped magnet 101 for generating torque according to the present invention has almost no useless magnetic flux, unlike the conventional magnet shown in FIG. And a higher surface magnetic field can be obtained. In the disc-shaped magnet shown in FIGS. 2 and 3,
The ring magnet 102 for signal generation at the end is also effectively focused on the center band at the end, so that the receiving sensitivity can be improved. Similarly, in the disk-shaped magnet shown in FIG. 4, the ring magnet 102 for signal generation on the outer peripheral portion is also effectively focused on the central band on the outer peripheral surface.

As the disk-shaped magnet of the present invention, either a synthetic resin magnet or a sintered magnet can be used. For example, as the magnetic powder in the synthetic resin magnet and the sintered magnet, any of conventionally known magnetic powders such as ferrite-based magnetic powder, alnico-based magnetic powder and rare earth-based magnetic powder such as samarium-cobalt-based magnetic powder and neodymium-iron-boron-based magnetic powder can be used. As for the particle shape, the average particle size is about 1.5 μm, and the compressed density is 3.20.
The above are preferred.

As the synthetic resin, any of conventionally known synthetic resins can be used, and typical examples thereof are as follows. Polyamide-based synthetic resins such as polyamide-6 and polyamide-12. Homo- or copolymerized vinyl synthetic resins such as polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polymethyl methacrylate, polystyrene, polyethylene, and polypropylene. 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. Further, the mixing ratio of the magnetic powder and the synthetic resin as the binder is as follows:
It is desirable to set the synthetic resin to about 10 for 90. In addition, it goes without saying that an appropriate amount of conventionally used plasticizers, antioxidants, 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. 5 to 7 schematically show preferred examples of a magnetic field orientation molding machine having an injection mold according to the present invention. The apparatus of FIG. 5 is advantageously adapted to the formation of the disc-shaped magnet shown in FIG. 2, and similarly, the apparatus of FIG. 6 is the same as the disc-shaped magnet shown in FIG. 3, and the apparatus of FIG. To a disc-shaped magnet
Each fits. In the figure, reference numeral 1 denotes a cavity provided in the die 2, 3 denotes a main pole, 4 denotes a counter electrode, and 5 denotes an auxiliary pole. In this example, the total area of the magnetic field application surfaces of the counter electrode 4 and the auxiliary pole 5 is defined as The structure is reduced with respect to the area. Reference numeral 6 denotes a fixed-side mounting plate, 7 denotes a fixed-side die plate, 8 denotes a movable-side die plate, 9 denotes a movable-side receiving plate, 10 denotes a spacer block, 11 denotes a movable-side mounting plate, 12 denotes an ejector plate, and 13 denotes an ejector pin. , 14 is a nozzle touch, 15 is a sprue runner, and 16 is a center pin.

In the figure, the main pole 3, counter electrode 4, auxiliary pole 5, fixed side mounting plate 6, movable side receiving plate 9, spacer block 10, movable side mounting plate 11, ejector plate 12, and ejector pin 13 are ferromagnetic. Body is used, while the fixed side template 7
A non-magnetic material is used for the movable mold plate 8. Then, a magnetic field is externally applied to the injection mold.

Here, as the ferromagnetic material, S55C, S5
Carbon steels such as 0C and S40C, die steels such as SKD11 and SKD61, pamenjur, pure iron, and the like can be used. However, it is more advantageous to perform a surface hardening treatment for improving abrasion resistance. On the other hand, non-magnetic materials include stainless steel,
Copper beryllium alloy, high manganese steel, bronze, brass and non-magnetic super steel N-7 are suitable, and it is advantageous to apply a surface hardening treatment to improve wear resistance as necessary.

The mold K shown in FIG. 5 is assembled into an injection molding machine shown in FIG. 8, and while the synthetic resin magnet material introduced into the disc-shaped cavity 1 is in a softened state, the magnetic material is removed. On the other hand, when a magnetic field is applied by the magnetic field generating coil C, the lines of magnetic force are transmitted so as to be focused on the counter electrode and the auxiliary pole, respectively, so that the axis of easy magnetization of the magnetic powder in the magnet material is oriented along the direction of the lines of magnetic force. It is oriented so as to focus on the two annular zones of the auxiliary pole and thus a focusing-type disc-shaped magnet as shown in FIG. 2 is obtained.

Here, from the viewpoint of the mold magnetic circuit, it is advantageous that the width of the magnetic pole is equal to or larger than the cavity width on the magnetic field application surface of the main pole, while the area of the counter electrode and the auxiliary pole facing the main pole is advantageous. Is that the counter electrode is 30 to 95%, more preferably about 50 to 90% of the area of the main electrode, and the auxiliary electrode is 1% of the area of the main electrode.
It is good to be about 30%, more preferably about 5-20%.
The reason is that if it exceeds 95% or 30%, the effect of improving the surface magnetic field is reduced, while if it is less than 30% or 1%, the substantial working surface on which the surface magnetic field appears becomes too narrow, and the intrinsic holding force of the magnet causes This is because demagnetization may occur.

It is also possible to provide an inclined surface gradient in the disk-shaped cavity and make the gradient equal to the direction of the magnetic force lines generated in the cavity. Given this slope gradient,
In the case of a magnet product, the magnetic leakage from the magnet slope is the smallest, and the surface magnetic field on the working surface can be maximized. Further, the disc-shaped magnet is preferably a hollow so-called donut shape in consideration of a case where it is to be incorporated into a motor later, but in the present invention, such hollowing is not always an essential requirement.

Next, FIGS. 9 and 10 show a compression mold according to the present invention. In the drawing, reference numeral 17 denotes a lower punch also serving as a main pole. On the side opposite to the lower punch (main pole) 17 with the cavity 1 interposed therebetween, the counter electrode 4 and the auxiliary pole 5 and the non-magnetic material 18 provided therebetween. In this example, the area of the magnetic field application surface of the counter electrode 4 and the auxiliary pole 5 is reduced compared to that of the lower punch (main pole) 17. Reference numeral 20 denotes a die, and when applied to the molding of the disk-shaped magnet shown in FIG. 4, a part of the die 20 serves as an auxiliary pole. And 21 is a center core.

In the figure, a ferromagnetic material is used for the lower punch 17, the counter electrode 4, and the auxiliary pole 5 (partly, a part of the die 20) constituting the main pole, while a part 18 of the upper punch, the die 2
0, a non-magnetic material is used as the center core 21. Then, a magnetic field is externally applied to the compression molding die. Note that, also in this mold, the material, the area ratio of the body pole and the auxiliary pole to the main pole, and the like are the same as in the case of the above-described injection mold.

[0024]

EXAMPLE Using a magnetic orientation machine having an injection mold as shown in FIGS. 5 to 7 and a compression mold as shown in FIGS. 9 and 10, the dimensions and shape shown in FIG. 11 were used. Was formed under the following conditions. The area of the counter electrode was 70% of the area of the main electrode, and the area of the auxiliary electrode was 10 or 15% of the area of the main electrode.

[0025]

[Table 1] Raw materials and magnetic powder particles Magnetic powder A: Ferrite magnetic powder (Magnetoplumbite strontium ferrite magnetic powder with an average particle diameter of 1.5 μm B: Samarium-cobalt magnetic powder (Sm ₂ Co ₁₇ type; average particle diameter 10 μm) A: Polyamide 12 Resin B: Epoxy

[0026]

[Table 2] Formulation / Formulation A Magnetic powder: 64 vol% Resin: 36 vol% ・ Formulation B Magnetic powder: 72 vol% Resin: 28 vol% ・ Formulation C Magnetic powder: 70 vol% Resin: 30 vol%

[0027]

[Table 3] Molding condition / Injection molding condition (Magnetic orientation injection molding machine with built-in coil) Pellet compounding: Compounding A Injection cylinder temperature: 300 ° C Mold temperature: 80 ° C Injection pressure: 1500 kgf / cm ² Excitation time: 5s Time ： 30s Injection cycle ： 50s ・ Compression molding condition (Magnetic orientation compression molding machine with a built-in coil) Material used: Formulation B Molding cycle: 5s Curing condition: 100 ℃, 3h

For comparison, in the molding dies shown in FIGS. 5 and 9, the areas of the counter electrode and the main electrode are made equal except for the auxiliary pole, and a uniform magnetic field is generated between the main electrode and the counter electrode. A disk-shaped magnet was formed in the same manner as described above using what was called axial orientation.

Tables 4 and 5 show the results obtained by examining the surface magnetic field after magnetizing the disk-shaped magnet thus obtained.

[0030]

[Table 4]

[0031]

[Table 5]

As is clear from the table, the magnetic powder in the disc-shaped magnet is oriented to the annular zone in the working surface or the central zone on the outer peripheral surface by using the magnetic field orientation molding machine according to the present invention. By orienting to the central zone, the surface magnetic field at the working surface can be greatly improved, and the effective magnetic field at a position slightly away from the surface is particularly excellent.

[0033]

As described above, according to the present invention, the magnetic powder can be effectively oriented in the annular zone in the working surface in the internal torque generating region in the disk-shaped magnet material. The surface magnetic field on the working surface of the permanent magnet can be significantly improved as compared with the related art. Also, since the sensitivity of the signal generation area can be greatly improved, the gap with the receiving element can be relaxed, the assembly cost can be reduced when the same receiving element is used, and when the gap is equal to the conventional one, , Signal reading errors can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a view showing a magnetic powder particle orientation of a conventional disk-shaped magnet.

FIG. 2 is a view showing a magnetic powder particle orientation of a disk-shaped magnet according to the present invention.

FIG. 3 is a view showing a magnetic powder particle orientation of a disk-shaped magnet according to the present invention.

FIG. 4 is a view showing a magnetic powder particle orientation of a disk-shaped magnet according to the present invention.

FIG. 5 is a schematic view of a magnetic field orientation molding machine provided with an injection molding die according to the present invention.

FIG. 6 is a schematic view of a magnetic field orientation molding machine having an injection molding die according to the present invention.

FIG. 7 is a schematic view of a magnetic field orientation molding machine provided with an injection molding die according to the present invention.

FIG. 8 is a schematic diagram of an injection molding machine.

FIG. 9 is a schematic diagram of a magnetic field orientation molding machine having a compression molding die according to the present invention.

FIG. 10 is a schematic view of a magnetic field orientation molding machine having a compression molding die according to the present invention.

FIG. 11 is a diagram showing the size and shape of a disk-shaped magnet produced in an example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cavity 2 Die 3 Main pole 4 Counter electrode 5 Auxiliary pole 6 Fixed side mounting plate 7 Fixed side type plate 8 Moving side type plate 9 Moving side receiving plate 10 Spacer block 11 Moving side mounting plate 12 Ejector plate 13 Ejector pin 14 Nozzle touch 15 Sprue runner 16 Center pin 17 Lower punch 18 Non-magnetic material 19 Upper punch 20 Die 21 Center core

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01F 7/02 H01F 13/00 H01F 41/02

Claims (3)

(57) [Claims] 1. A disk-shaped magnet having one of its front and back surfaces as an active surface, wherein the orientation direction of the magnetic powder particles in the thickness direction of the magnet is two concentric annular zones in the active surface. A focused multi-oriented disc-shaped magnet, wherein the magnets are respectively focused, and a total area of the annular zone is smaller than an active surface area. 2. A disc-shaped magnet having either one of the front and back surfaces of the disc and the outer peripheral surface of the disc as an acting surface, wherein the orientation direction of the magnetic powder particles in the thickness direction of the magnet is one of the front and back surfaces of the disc. A focusing composite orientation characterized in that the annular zone in the working surface and the central zone on the outer peripheral surface of the disk are respectively focused, and each area of the annular zone and the central zone is smaller than the area of each corresponding working surface. Type disk magnet. 3. 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 and orienting magnetic powder in the material in a predetermined direction, wherein a working surface of the cavity is formed. The constituent counter electrode and auxiliary electrode, and the main electrode constituting the non-working surface, which are arranged to face each other with the cavity interposed therebetween, are arranged, and the area of the counter electrode and the auxiliary electrode is made smaller than the area of the main electrode. Magnetic field orientation molding machine.