JPH0736371B2 - Method for manufacturing multipolar anisotropic resin magnet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] Conventionally, a resin magnet having a multipolar anisotropic orientation is an isotropic material formed by kneading a magnetic powder and a polymer material without orienting the magnetic powder. A method of magnetizing resin molded products with multiple poles, and N, S2
Most of them were prepared by a method of multi-pole magnetizing an anisotropic resin molded product in which magnetic powder was oriented in radial anisotropy or axial anisotropy by a bending magnetic field. In consideration of easiness of magnetization, it is preferable that the resin molded product is previously orientated radially or axially anisotropically as in the latter case.

In order to obtain the above-mentioned radial or axial anisotropic resin molded product, the resin may be molded in the space (cavity) where the N and S2 poles face each other as shown in the sectional view of FIG. 2-1. This method has the advantage that an orientation degree of 95% or more can be obtained because a sufficient orientation magnetic field can be applied to the cavity of the molded product. Furthermore, in order to improve the timing characteristics, the magnetic powder containing It is possible to shape and orient the deeper inside even in the case where the flow orientation is deteriorated by increasing both.

[Problems to be solved by the invention]

However, when a radially or axially anisotropic oriented molded product is attached to multiple poles, the magnetic flux path 6 (6 in Fig. 2-2) used for magnetization is located at a part inside the molded product. , The easy axis of magnetization of magnetic powder (the direction in which magnetic powder is easily magnetized) and 90
Since the orientation is high, the orientation itself is high, but the orientation is different by a part, so the magnetism is regulated in that part, and the magnetic performance is considerably low as the performance of the material. There was a big fundamental problem that we had to do it. Moreover, the above method cannot be applied to a solid magnet roll.

As a method for solving the above-mentioned problems, a method of magnetizing a resin molded product which is preliminarily multipolar anisotropically oriented in a shape similar to a magnetic circuit used for magnetizing is recently used. ing. In this method, for example, as shown in the sectional view of FIG. 3-1, a molded product is prepared in a cavity in which N and S poles are alternately applied.

The resin molded product obtained by this method has the same orientation direction as the magnetic circuit used for magnetization, but the N and S pole structures for generating a multipolar orientation magnetic field do not become opposing magnetic poles. In comparison with the above-mentioned radial anisotropic orientation, gap gap permeance used in the case of axial anisotropic orientation, in this method, the magnetic field generated only by the leakage permeance must be used for orientation. As a magnetic field, there is a theoretical defect that the magnetic field is reduced to a fraction of one to several tenths as compared with the case of opposing magnetic poles (radial anisotropic orientation, axial anisotropic orientation). As for the depth of orientation itself, magnetic flux hardly passes in the radial direction or thickness direction of the molded product like the opposing magnetic poles. Therefore, as the number of poles increases, only the surface layer can pass the magnetic flux, and only the surface layer. However, the orientation no longer occurs, and most of the others remain isotropic, and most of them do not contribute to the improvement of magnetic properties. Furthermore, in the case of multiple poles, since the distance between the N and S magnetic poles becomes short, the magnetic flux leaks directly between the magnetic poles without passing through the cavity, and the efficiency decreases greatly due to the reduction of the orientation magnetic field itself and its synergistic effect. It was dead.

In addition, since high-performance materials with a high content of magnetic powder that could be used without problems in radial anisotropic orientation and axial anisotropic orientation have poor flow orientation, they are hardly orientated in multipolar molding orientation. There was a major principle flaw that it could not be done.

As described above, even if the multipolar anisotropic orientation molding method is used, only those having a small magnetic powder content and low magnetic properties can be used. As a result, there was no big difference with the oriented high-performance materials. Therefore, the one that cannot be radially oriented like a solid magnet roll,
The range of use was limited, such as in the case where a resin magnet having a small content of magnetic powder and a small specific gravity is particularly required.

[Object of the Invention]

The present invention has been made in view of the above conventional problems,
The purpose thereof is a method for producing a resin magnet having a multipolar anisotropic oriented portion capable of sufficiently exerting magnetic performance, particularly for a resin magnet having a multipolar anisotropic orientation not only in the surface layer but also deep inside. It is to provide a manufacturing method.

[Means for solving problems]

The above object of the present invention is to anisotropically orient the magnetic powder by applying a magnetic field to the resin magnet composition containing the magnetic powder while maintaining the molten state in the cylindrical or columnar cavity. A method for producing a multipolar anisotropic resin magnet, which comprises a step of cooling and curing the composition from the above, wherein the step of cooling and curing after anisotropically aligning the multipolar anisotropic orientation to the inside of the cavity Magnetic pole is inserted, and while the resin magnet composition containing magnetic powder is present in a molten state in the other cavity, a magnetic field is applied by the magnetic pole to orient the magnetic powder in a multipolar anisotropy and then it is cooled and hardened. And the subsequent step of allowing the resin magnet composition containing magnetic powder to exist in a molten state in the space of the shape in which the magnetic pole is pulled out in the radial direction until the tip of the magnetic pole comes to a position on the outer circumference of the cavity. Magnetized by the magnetic pole It is achieved by the method for manufacturing a multipolar anisotropic resin bonded magnet and a step of cooling curing the magnetic powder were allowed to multipolar anisotropy oriented over.

That is, the present invention comprises two steps of molding orientation.

FIGS. 1-1 to 1-4 schematically show the principle of the method for producing a polar resin magnet of the present invention.

In the figure, 1 is a north pole, 2 is a south pole, 3 is a cavity (space for molding a molded product) or a molded product molded in the cavity, and 4 is included in the molded product. 5 schematically shows the orientation of the magnetic powder having an easy axis of magnetization, and 5 schematically shows the direction of the flow of magnetic flux due to the orientation magnetic field. The N pole 1 and the S pole 2 guide the magnetic field generated outside the mold to the cavity and generate the magnetic field inside the cavity. Although the molded product is cylindrical in this example, it may be cylindrical.

The method for producing an anisotropic resin magnet of the present invention is carried out, for example, by the following two steps of molding orientation.

As the first molding orientation step, first, as shown in the sectional view of FIG. 1-1, a plurality of magnetic poles (alternately, N poles 1 and S poles 2 are alternately arranged in a cavity 3 in which a resin molded product is molded. ) Is inserted. A magnetic field is generated in the cavity 3 by applying a magnetic field to the N pole 1 and the S pole 2, and the composition of the resin magnet in a molten state is injected and injected. At this time, the strongest magnetic field is applied to the opposing gaps between the tips of the N pole 1 and the S pole 2, the magnetic flux flows as shown by 5 and the magnetic powder is oriented as shown by 4. When this composition was cooled and cured and the magnetic pole was removed,
A molded product 3 whose partial sectional view is shown in FIG. 3 is obtained.

Next, as the second molding orientation step, the N pole 1 and the S pole 2 are drawn and arranged in the radial direction so as to be in contact with the outer periphery of the cavity so that the molded article can be molded into the final shape ( 1-2), in this state, the composition is injected into the space after the magnetic pole is pulled out while applying the magnetic field to the magnetic pole again. The flow of magnetic flux at this time is as shown by 5 in FIG. 1-2. When cooled and cured, a molded product (final molded product of a desired anisotropic resin magnet) whose orientation of magnetic powder is schematically shown in FIG. 1-4 is obtained.

According to the present invention, a solid magnet roll having good magnetic properties can be obtained. Further, a high-performance resin magnet having a large content of magnetic powder can be obtained.

In the step of the second molding orientation, the magnetic flux is oriented so that a magnetic chain is generated between the magnetic pole and the first molding orientation portion to facilitate easy magnetization. Therefore, it is possible to obtain a multipolar molded product having a high degree of orientation even deep inside the molded product.

In the present invention, the shape of the magnetic pole used to be inserted into the cavity and to be projected into the molded product may be determined by the magnetic flux distribution desired to be given to the molded product.

Further, in the present invention, the composition of the resin magnet used in the first molding orientation and the composition used in the second molding orientation are not limited to the same ones, but may be used in the first time when the orientation magnetic field is strongly applied. A composition having a high magnetic powder content may be used, and a composition having a low magnetic powder content may be used for the second time.

The method of generating the multipolar anisotropic orientation magnetic field is not limited to the above method, and a pulse magnetic field may be used.

Further, as a method for allowing the molten magnetic powder-containing polymer material to exist in the cavity, a two-color molding method, a multi-stage injection molding method, a transfer method, a hot pressing method, a reaction molding method, or the like can be used.

The composition of the anisotropic resin magnet produced by the method for producing an 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, rare earth metal such as samarium-cobalt-based material, or the like can be used, but ferrite that requires less energy for magnetization is preferably used. You may mix and use a ferrite and a rare earth metal. 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 relative to the weight of the resin magnet composition.
It is in the range of wt% to 90 wt%.

As the lubricant, stearic acid metal salt or bisamide type is used, and as the surface treatment agent, silane type, titanate type or the like is used.

〔The invention's effect〕

In the method for producing an anisotropic resin magnet of the present invention, multipolar anisotropic orientation can be performed magnetically efficiently with a small amount of energy. , A magnetic resin magnet can be obtained, and a multipolar anisotropic orientation can be easily performed even for a material having a high fluidity and a high magnetic powder content and poor fluidity.

[Brief description of drawings]

FIG. 1-1 is a schematic cross-sectional view showing the first molding orientation in the method for producing a (multipolar) anisotropic resin magnet of the present invention, and FIG. 1-2 shows the second molding orientation. 1 is a schematic cross-sectional view showing a molded product after the first molding orientation, and FIG. 1-4 is a molded product after the second molding orientation (final molding). FIG. FIGS. 2-1 and 2-2 are schematic views of a die magnetic pole part and a molded product by radial anisotropic orientation molding of a conventional example, and FIGS. 3-1 and 3-2 show conventional examples. FIG. 5 is a schematic view of a die magnetic pole part and a molded product according to an example of multipolar anisotropic molding orientation. 1: N pole 2: S pole 3: Molded product or cavity 4: State of orientation of ferrite magnetic powder 5: Flow of magnetic flux during orientation 6: Magnetic pole for multi-pole anisotropic magnetization

Claims (1)

[Claims] 1. A resin magnet composition containing magnetic powder is anisotropically oriented by applying a magnetic field to the cavity while maintaining a molten state in the cylindrical or columnar cavity. A method for producing a multipolar anisotropic resin magnet having a step of cooling and curing the composition, wherein the step of cooling and curing after anisotropically orienting is performed for multipolar anisotropic orientation even inside the cavity. A step of inserting a magnetic pole, allowing a magnetic field to be applied by the magnetic pole while allowing a resin magnet composition containing magnetic powder to exist in a molten state in the other cavity portion, and then causing the magnetic powder to undergo multipolar anisotropic orientation and then cooling and hardening. Then, while the composition of the resin magnet containing magnetic powder is present in a molten state in the space of the shape in which the magnetic pole is pulled out in the radial direction until the tip of the magnetic pole reaches the position on the outer periphery of the cavity, A magnetic field is applied by Method of manufacturing a multipolar anisotropic resin bonded magnet, characterized in that a step of cooling curing sex flour by multipolar anisotropy orientation.