JPH071727B2 - 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. 3, 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. 4, 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 having 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 the more magnetic poles the main magnetic flux from the magnetic pole passes through only the surface, which is the shortest distance, without passing through the deep portion of the molded product. 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 object of the present invention comprises an outer layer which is a resin magnet, and an inner layer which is inscribed in the outer layer and which contains a substance mixed with magnetic powder and at least one of iron, cobalt and nickel. A cylindrical or cylindrical anisotropic resin magnet, characterized in that the outer layer is magnetically anisotropically oriented, and a cavity of a mold for molding the resin magnet. Inside, an inner magnet made of a mixture of magnetic powder and at least one of iron, cobalt and nickel and a binder material in a weight ratio of 70/30 to 90/10 is arranged. In the cavity, a resin molding cavity for forming an outer magnet is provided between the inner magnet and the cavity of the mold, and a magnetic pole member for magnetic anisotropic orientation is arranged in the mold. Inject resin material containing magnetic material into The implanted magnetic material of the resin material is anisotropic orientation, the inner magnet and the outer magnet is achieved by a method for producing an anisotropic resin magnet integrated.

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 is a mixture of the outer layer 1 (cylindrical resin magnet) magnetically oriented in the radial direction and having ferromagnetism or hard magnetism, and magnetic powder and at least one of iron, cobalt and nickel. The inner layer 2 contains.

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

As indicated by the arrow, magnetic flux flows in the outer layer 1 in the radial direction (inward direction), which is the orientation of the magnetic powder. When the magnetic flux reaches the inner layer 2, the magnetic flux changes its direction in the circumferential direction in the inner layer 2 and reaches the position on the inner diameter side of the adjacent pole. Flowing.

That is, the inner layer 2 acts as a back yoke,
In the anisotropic resin magnet of the present invention, a magnetic flux magnetically closed circuit is formed to improve magnetic performance.

The inner layer contains a substance mixed with magnetic powder and at least one of iron, cobalt and nickel.
This is to reduce the magnetic resistance and facilitate the passage of magnetic flux.

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 outer layer of the anisotropic resin magnet of the present invention contains magnetic powder and a binder as main components, and a lubricant and the like are added.

As the magnetic powder, ferrite, samarium cobalt, which is a rare earth metal, or the like can be used, but 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 binder and the magnetic powder is in the range of 30/70 to 10/90.

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

The inner layer of the anisotropic resin magnet of the present invention is composed of a substance in which magnetic powder is mixed with at least one of iron, cobalt and nickel, vine bar and the like. The mixing ratio (weight ratio) of this substance and the binder is preferably about 70/30 to 90/10.

The same material as that which can be contained in the outer layer is used as the binder.

The anisotropic resin magnet of the present invention is obtained by the manufacturing method of the present invention based on 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.

As described above, since the anisotropic resin magnet of the present invention is provided with the layer containing both the ferromagnetic substance and the soft magnetic substance on the inner diameter side, it means that the back yoke is provided and the performance as the magnet is improved. high.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY The anisotropic resin magnet of the present invention has a strong magnetic performance in the radial direction because the magnetic flux is closed. As a result, 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]

FIG. 1 is a schematic view of an anisotropic resin magnet of the present invention.
The figure is a schematic diagram showing the flow of magnetic flux in the magnet. FIG. 3 is a radial anisotropic oriented resin magnet, FIG. 4 is a polar anisotropic oriented resin magnet (multipole), and FIG. 5 is a polar anisotropic oriented resin magnet (4
Pole). 1: Cylindrical resin magnet magnetically oriented in the radial direction (outer layer) 2: Layer (inner layer) made of a substance having both ferromagnetism and soft magnetism N: N pole S: S pole

Claims (2)

[Claims] 1. An anisotropic method comprising an outer layer which is a resin magnet and an inner layer which is inscribed in the outer layer and which contains a substance mixed with magnetic powder and at least one of iron, cobalt and nickel. Columnar or cylindrical anisotropic resin magnet, wherein the outer layer is magnetically anisotropically oriented. 2. A weight ratio of 70 parts by weight of a material obtained by mixing magnetic powder with at least one of iron, cobalt and nickel and a binder material in a cavity of a mold for molding a resin magnet.
An inner magnet formed by mixing in a ratio of / 30 to 90/10 is arranged, 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 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 magnetically anisotropy oriented. A method for manufacturing a cylindrical or cylindrical anisotropic resin magnet by integrating the outer magnet with the outer magnet.