JPH071726B2 - Anisotropic resin magnet and manufacturing method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a cylindrical or cylindrical resin magnet,
Particularly, it relates to an anisotropic resin magnet having magnetic anisotropy in the radial direction.

[Conventional technology]

BACKGROUND ART Cylindrical resin magnets such as cylindrical isotropic resin magnets and cylindrical radial anisotropic oriented resin magnets, which are used for stepping motors used in cameras, copying machines, and other devices, have been known. There is.

In the isotropic resin magnet, the magnetic powder in the resin magnet material is mixed in an indefinite direction, and the easy axis of magnetization of each magnetic powder is oriented in an indefinite direction, so the magnet characteristics after magnetization are low.

On the other hand, in the radial anisotropic oriented resin magnet as shown in FIG. 5, the easy axis of magnetization of the magnetic powder is oriented radially in the radial direction of the cylindrical resin magnet, and the magnet characteristics after magnetization are isotropic. Is better than the magnetic resin magnet.

Most of the methods for producing the cylindrical resin magnet having the radial anisotropic orientation are such that magnetic powder is magnetically oriented in the radial direction at the time of molding, and magnetization is performed along the magnetic orientation. . This resin magnet magnetically oriented in the radial direction is excellent in industrial productivity, and its orientation can be easily made very high. However, since this orientation is a linear one direction, the orientation does not match the direction of the magnetic flux applied when the outer periphery is magnetized in multiple poles. Therefore, the magnetic flux passing through the magnet after magnetization is only in the radial direction, and is magnetically closed outside the magnet in the air having a large magnetic resistance, and the characteristic becomes weak.

Further, in order to further improve the magnet characteristics, as shown in FIG. 6, a polar anisotropic oriented resin magnet showing a polar anisotropic orientation in the outer peripheral direction of a cylindrical resin magnet is considered to be good. . However, such a conventional polar anisotropic oriented resin magnet has a cylindrical shape and a cylindrical shape as compared with a multipolar polar anisotropic oriented product with a small number of poles as shown in FIG. There is a drawback that the degree of orientation of the magnetic powder decreases more as the number of poles of the resin magnet increases. That is, there is a principle defect that as the number of poles increases, the main magnetic flux from the orienting magnetic pole does not pass through the deep portion of the molded product but only through the surface which is the shortest distance. Therefore, the depth of orientation from the surface layer does not change even if the thickness of the molded product is increased to improve the magnetic characteristics of the magnet to raise the operating point. However, when it is used as a high-speed rotating body, only the moment of inertia becomes large, and the starting frequency and maximum response frequency are reduced. Was there. Further, this method has a problem that it is not easy to orient the magnetic powder and the productivity is poor.

The present invention has been made in view of the above problems, and an object thereof is to obtain an anisotropic resin magnet having good productivity and further improved radial magnetic characteristics.

[Means for solving problems]

The above-mentioned object of the present invention is a cylindrical or cylindrical anisotropic resin magnet comprising an outer layer which is a cylindrical resin magnet and an inner layer which is a resin magnet inscribed in the outer layer, wherein the outer layer Is anisotropically magnetically oriented in the radial direction, and the inner layer is polarically anisotropically oriented, and an anisotropic resin magnet and a mold for molding the resin magnet. A columnar or cylindrical inner magnet having polar anisotropic orientation is arranged in the cavity, and a resin molding cavity portion for forming an outer magnet is provided between the inner magnet and the cavity of the mold. A magnetic pole member for magnetic anisotropy orientation in the radial direction is arranged in the mold to inject a resin material containing a magnetic material into the cavity, and the magnetic material of the injected resin material in the radial direction. A magnetic anisotropy is oriented and the inner magnet and outer magnet are integrated into a circle. This is achieved by a method of manufacturing a columnar or cylindrical anisotropic resin magnet.

One embodiment of the anisotropic resin magnet of the present invention (cylindrical one)
A schematic diagram of is shown in FIG.

The cylindrical resin magnet in the figure comprises a cylindrical resin magnet 1 (outer layer) magnetically oriented in the radial direction and a cylindrical resin magnet 2 (inner layer) oriented in polar anisotropy.

The flow of magnetic flux inside the cylindrical resin magnet of the present invention is shown in FIG.

As shown by the arrow, in the cylindrical resin magnet 1, magnetic flux flows in the radial direction (inward direction), which is the orientation of the magnetic powder. When the magnetic flux reaches the cylindrical resin magnet 2, the magnetic flux changes its direction in the circumferential direction along the direction of the magnetically easy axis oriented in polar anisotropy and reaches the position on the inner diameter side of the adjacent pole. It changes its direction (outward) and flows into the adjacent pole.

That is, the layer of the cylindrical resin magnet 2 plays the role of a back yoke and creates a circuit in which magnetic flux is magnetically closed in the magnet to improve the magnetic performance.

The inner layer of the anisotropic resin magnet of the present invention is not limited to the cylindrical shape as described above, and may be a columnar shape.

The anisotropic resin magnet of the present invention contains magnetic powder and a binder as main components, and further contains a lubricant and the like.

As the magnetic powder, a rare earth metal such as a ferrite-based material or a samarium-cobalt-based material can be used, but a ferrite that requires less energy for magnetization is preferably used. Specific examples of ferrite used include strontium ferrite and barium ferrite.

As the binder, any conventionally known binder material for resin magnets such as polyamide, polybutylene terephthalate, and polyphenylene sulfide is used. The mixing ratio of the magnetic powder is about 70 wt with respect to the weight of the resin magnet composition.
% To 90 wt%.

As the lubricant, stearic acid, metal salts, bisamides, etc. are used, and as the surface treatment agent, silanes, titanates, etc. are used.

The anisotropic resin magnet of the present invention is obtained by the manufacturing method of the present invention based on the Ne insert molding. Further, it can be manufactured by a method other than this, for example, a simple method such as integrally molding the inner layer and the outer layer by a method such as two-color molding or fitting the inner layer and the outer layer separately molded by the method. However, in the method using adhesion or the like, it is necessary to increase the dimensional accuracy of the adhesion surface, and the adverse effect of the magnetic field due to the intermediate adhesion layer causes a bad result. On the other hand, according to the manufacturing method of the present invention based on insert molding, the adhesion is good, there is no adverse effect on the magnetic flux of the magnetic field, and the coupling between the inner magnet and the outer magnet is strengthened by the contracting action of the insert after molding the outer magnet portion. It becomes possible to integrate the magnetic field circuit.

One embodiment of the manufacturing method of the present invention will be described with reference to FIG.

In FIG. 4, reference numeral 2 denotes an inner resin magnet that is polar-anisotropically oriented in advance, and reference numeral 4 denotes a magnetic flux for radially outwardly orienting the outer resin magnet. An outer resin magnet molding cavity 5 is molded from the inner resin magnet 2 and the molding surface of the mold.

First, a cavity having a polar anisotropically oriented inner resin magnet 2 and a magnetic pole 3 for radial anisotropic orientation on the molding surface is provided in a cavity 5 in which a magnetic pole of the inner polar anisotropically oriented magnet 2 and a magnetic pole for radial anisotropic orientation are formed. 3 are installed so as to oppose each other, and a magnetic field is applied to the radial anisotropic orientation magnetic pole 3 to hold the magnetic flux 4, and the cavity 5 is filled with a molten resin magnet material to form a magnetic powder. After being oriented in the direction of the magnetic flux 4, cooled and solidified, an anisotropically oriented resin magnet with a closed magnetic flux, such as the polar anisotropic orientation shown in FIG. 1, was obtained.

If the number of magnetic poles for radial anisotropic orientation is increased by the above manufacturing method, an anisotropic oriented resin magnet having more poles as shown in FIG. 3 can be obtained.

In the above-mentioned embodiment, the first anisotropic molded product was inserted into the multipolar cavity as shown in FIG. 4 to perform the molded alignment. Can also be oriented by inserting and molding into a N, S bipolar bipolar orientation die as shown in FIG. Since this method has only two poles, N and S, it is possible to apply a strong magnetic field by making the insert molded product stick out.

As described above, since the anisotropic resin magnet of the present invention is provided with the polar anisotropic oriented resin magnet on the inner diameter side, it means that the back yoke is provided and the performance as a magnet is high.

〔The invention's effect〕

The anisotropic resin magnet of the present invention has a strong magnetic performance in the radial direction because the magnetic flux is closed. The magnetic flux reaches the central portion of the resin magnet regardless of whether it has a large diameter or is magnetized in multiple poles. The magnetic performance does not deteriorate. ・ Even though the magnetic flux is closed, the manufacturing method is simple, and so on. Further, according to the manufacturing method of the present invention, the adhesion is good, there is no adverse effect on the magnetic flux of the magnetic field, the coupling between the inner magnet and the outer magnet is strengthened by the contracting action of the insert after molding the outer magnet portion, and Integration is possible.

[Brief description of drawings]

1 and 3 are schematic diagrams of the anisotropic resin magnet of the present invention, FIG. 2 is a schematic diagram showing the flow of magnetic flux in the magnet, and FIG. 4 is a schematic diagram showing insert molding. Yes, fifth
FIG. 6 is a schematic plan view of a cylindrical resin magnet that is anisotropically oriented in the radial direction, FIGS. 6 and 7 are schematic plan views of a resin magnet that is polar anisotropically oriented, and FIG. It is a schematic diagram which shows the example of a method. 1: Cylindrical resin magnet with magnetic orientation in the radial direction (outer layer) 2: Cylindrical resin magnet with polar anisotropic orientation (inner layer) 3: Magnetic pole for radial anisotropic orientation 4: Magnetic flux 5: Cavity

Claims (2)

[Claims] 1. A cylindrical or cylindrical anisotropic resin magnet comprising an outer layer, which is a cylindrical resin magnet, and an inner layer, which is a resin magnet provided inscribed in the outer layer, wherein the outer layer has a diameter. An anisotropic resin magnet, characterized in that it is magnetically anisotropic oriented in a direction and the inner layer is polar anisotropically oriented. 2. A cylindrical or cylindrical inner magnet having polar anisotropic orientation is arranged in a cavity of a mold for molding a resin magnet, and an outer side is provided between the inner magnet and the mold cavity. Providing a resin molding cavity for forming a magnet,
A magnetic pole member for magnetic anisotropy orientation in the radial direction is arranged in the mold, a resin material containing a magnetic material is injected into the cavity, and the magnetic material of the injected resin material is magnetized in the radial direction. A method for producing a columnar or cylindrical anisotropic resin magnet by anisotropically orienting and integrating the inner magnet and the outer magnet.