JPH0654742B2 - Method for manufacturing multipolar anisotropic resin magnet - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing an anisotropic resin magnet, and in particular, anisotropy in which multipolar anisotropic orientation can be easily carried out to a deep portion of the anisotropic resin magnet. The present invention relates to a method for manufacturing a resin magnet.

[Conventional technology]

Conventionally, resin magnets with multipolar anisotropic orientation have been manufactured by kneading magnetic powder and polymer material and magnetizing the isotropic resin molded product without orienting the magnetic powder. N,
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 magnetic field of S2 pole. 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 a space (cavity) where N and S2 poles face each other, as shown in the sectional view of FIG. 2-1. This method has the advantage that a sufficient orientation magnetic field can be applied to the cavity of the molded product, so that an orientation degree of 95% or more can be obtained. Furthermore, in order to improve magnetic characteristics, magnetic powder is included. It is possible to form and orient the deeper inside even in the case where the flow orientation is deteriorated by increasing the amount.

[Problems to be solved by the invention]

However, when a radially or axially anisotropic oriented molded product is attached to multiple poles, the magnetic path 6 (the first
2-2 6) in the figure is oriented 90 ° with the easy axis of magnetization of the magnetic powder (the direction in which the magnetic powder is easily magnetized) in a part inside the molded product, so the degree of orientation itself is Although it is high, the orientation direction is different by 1 part, so that the magnetism is restricted at that part, and there is a major theoretical problem that the magnetic performance must be used at a place where the performance of the material is considerably low.

As a method for solving the above-mentioned problems, recently, a method of magnetizing a resin molded article which is preliminarily multipolar anisotropically oriented in a shape similar to a magnetic circuit used for magnetizing has been used. There is. 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 the orientation magnetic field in the multipoles do not become opposing magnetic poles. In the above-mentioned radial anisotropic orientation, in comparison with the 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. The magnetic field had a theoretical defect that the magnetic field was one to several tenths to several tens of minutes as compared with the case of opposing magnetic poles (radial anisotropic orientation, axial anisotropic orientation), and the orientation itself. Since the magnetic flux hardly penetrates in the radial direction or thickness direction of the molded product like the opposing magnetic poles, the higher the number of poles, the more the magnetic flux passes through the surface layer only, and the orientation occurs only in the surface layer. Kuna' would have, most other remains have become isotropic, where does not contribute to the improvement of the magnetic characteristics were the majority. Furthermore, in the case of multiple poles, the distance between the N and S magnetic poles becomes short, and the efficiency decreases greatly due to the synergistic effect with the decrease in the orientation magnetic field itself due to direct leakage of magnetic flux between the magnetic poles without passing through the cavity. It was dead.

Also, because of this, high-performance materials with a high content of magnetic powder, which could be used without problems in radial anisotropic orientation and axial anisotropic orientation, have poor flow orientation, so in multipolar molding orientation, There was a major principle drawback that it was not oriented and could not be used.

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.

[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 includes a step of anisotropically orienting the magnetic powder by applying a magnetic field to the cavity while keeping the resin magnet composition containing the magnetic powder in a molten state in the cylindrical cavity. A method for producing a multipolar anisotropic resin magnet, wherein as a step of anisotropically orienting, a radial or axial anisotropically orienting magnetic field is applied from the inner and outer peripheral sides of the catty to radially or axially orient the magnetic powder. Achieved by a method for producing a multi-pole anisotropic resin magnet, which includes a step and a step of subsequently applying a multi-pole anisotropic orientation magnetic field from the outer peripheral side of the cavity to partially orient the magnetic powder To be done.

Regarding the method for producing the multipolar anisotropic resin magnet of the present invention, 1-1
This will be described with reference to FIGS. 1 to 4.

FIGS. 1-1 to 1-3 are schematic views showing the relationship between the molded product in the mold cavity and the distribution magnetic poles.

In FIGS. 1-1 to 1-3, 1 is an N pole for radial anisotropic orientation, 2 is an S pole for radial anisotropic orientation, 3 is a molded product (or cavity), 4 is ferrite Magnetic powder, 5 is a magnetic flux flow for radial anisotropic orientation, 7 is a radial anisotropic orientation magnetic field generating coil, 8 is a demagnetizing coil, and 9 is a multipolar anisotropic orientation in which N and S poles are alternately applied. Is a coil for a pulsed magnetic field, and 10 is a magnetic field for multipolar anisotropic orientation.

Further, in FIG. 1-4, a is a graph showing a current waveform for radial anisotropic orientation, b is a graph showing a current waveform for high frequency attenuation demagnetization, and c is a current waveform for multipolar anisotropic orientation due to a pulse magnetic field. It is a graph showing.

As an embodiment of the method for producing a multi-pole anisotropic resin magnet of the present invention, first, an N-pole for radial anisotropic distribution of a die as shown in FIG. In the space (cavity) between the S poles 2 for sex distribution, the mixture of the magnetic powder and the polymer material is kept in a molten state such that the magnetic powder can easily change its direction, and the radial difference is generated. A direct current having a waveform shown in a of FIG. 1-4 is applied to the orientation coil 7. The magnetic flux generated by this coil passes through the radially anisotropically oriented magnetic pole N pole 1, passes through the inside of the molded product 3, and becomes a magnetic flux 5 for radial anisotropic orientation as shown in FIG. It flows to the magnetic pole S for polar orientation 2 and becomes a closed loop.

At this time, magnetic powder (for example, ferrite magnetic powder) is arranged in the radial direction inside the molded product as shown in FIG. 1-2. The resin magnet material is allowed to exist in a molten state in the cavity, and the order in which the current is applied to the coil is not limited to the above.If the current is applied to the coil and the magnetic field is generated in the cavity, the resin magnet material May be injected, and in this case, the step of injection and orientation is completed in about 0.5 seconds to 1 second, depending on the material and magnetic field conditions.

Next, the current for radial anisotropic orientation is cut off and a demagnetizing current having a waveform shown in b of FIG. 1-4 is passed. For this demagnetizing current, a current having a frequency response as high as possible is used so as not to change the direction of the ferrite magnetic powder. For example, in comparison with the radial orientation coil, the demagnetizing coil can reduce the inductance of the coil by reducing the number of turns and can apply the reverse pulse magnetic field with a short pulse width.
It can be demagnetized in 10,000 seconds.

Next, a multipolar anisotropic orientation magnetic field 10 is generated by causing a pulse current c having a waveform shown in FIG. 1-4 to flow in the cavity through the pulse magnetic field generation coil 9 shown in FIG. 1-3. As a result, the magnetic powder that had been oriented in two radial directions until now,
What is in the part where the magnetic field for multipolar anisotropic orientation 10 is strongly applied changes its orientation as shown in FIG. 1-3 to become multipolar anisotropic orientation. The weak points remain in the radial anisotropic orientation.

After being orientated twice as described above, it is cooled and solidified to obtain an anisotropically oriented resin magnet having a multipolar anisotropically oriented portion.

The method for generating the demagnetizing magnetic field is not limited to the method described above, and a magnetic field having a short pulse width of about 1/10000 second is applied to the pulse magnetic field generating coil 9 to demagnetize only the necessary portion, and then Wide pulse width for orientation 1/100 to 1/10000
It is also possible to apply a pulsed magnetic field of about a second.

Further, as a method of allowing the molten magnetic powder-containing polymer material to exist in the cavity, an 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, a rare earth metal type such as a ferrite type or a samarium cobalt type 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 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 salts, bisamides, etc. are used, and as the surface treatment agent, silanes, titanates, etc. are used.

In the method for producing an anisotropic resin magnet of the present invention, since a magnetic field for multipolar anisotropic alignment is applied after radial or axial anisotropic alignment, the magnetic field for multipolar anisotropic alignment is deep inside the molded product. Is induced. This is because the magnetic field for multipolar anisotropic orientation causes magnetic chains with the magnetic powder oriented in radial anisotropy, and the magnetic field can easily reach deep.

Further, as described above, since the magnetic field is efficiently applied and the force for orienting the magnetic powder is large, it becomes possible to use a high-performance material containing a large amount of magnetic powder, and a higher-performance plastic magnet can be obtained. It became so.

〔The invention's effect〕

In the method for producing an anisotropic resin magnet according to the present invention, since the entire magnet is anisotropically oriented without leaving isotropicity, magnetic efficiency is good. Multipolar anisotropic orientation is magnetically efficient with a small amount of energy. It can be well done. Multi-pole anisotropic orientation is carried out to the deep part of the resin magnet, so an anisotropic resin magnet with good performance can be obtained. For materials with high magnetic powder content and poor fluidity for high performance Also has an effect such as easy orientation.

[Brief description of drawings]

FIG. 1-1 is a schematic cross-sectional view of a mold for multipolar anisotropic molding alignment according to the present invention, and FIG. 1-2 is a magnetic flux in a state in which a magnetic field for radial anisotropic alignment according to the present invention is applied. FIG. 1-3 is a schematic diagram showing the state of flow and orientation, and FIG. 1-3 is a schematic diagram showing the state of flow and orientation of magnetic flux when a multipolar anisotropic orientation magnetic field is applied after demagnetization. -4 is a graph showing the excitation current waveform flowing in each coil. Figures 2-1 and 2-2 are schematics of the die magnetic pole part and the molded product by the conventional radial anisotropic orientation molding. FIG. 3-1 and FIG. 3-2 are schematic diagrams of a die magnetic pole part and a molded product according to a conventional example of multipolar anisotropic molding orientation. 1: N pole for radial anisotropic orientation 2: S pole for radial anisotropic orientation 3: Molded product 4: Ferrite magnetic powder 5: Magnetic flux flow for radial anisotropic orientation 6: Multipolar anisotropic deposition Magnetic path for magnetic flux (flow of magnetic flux actually used) 7: Radial anisotropic orientation magnetic field generating coil 8: Demagnetization coil 9: Multipolar anisotropic orientation pulse magnetic field coil 10: Multipole different Magnetic field for anisotropic orientation 10 a: Graph showing current waveform for radial anisotropic orientation b: Graph showing pulse current waveform for demagnetization c: Graph showing current waveform for multipolar anisotropic orientation by pulse magnetic field

Claims (1)

[Claims] 1. A multipole device comprising a step of anisotropically orienting magnetic powder by applying a magnetic field to the cavity while keeping a resin magnet composition containing magnetic powder in a cylindrical cavity in a molten state. In the method for producing an anisotropic resin magnet, as a step of anisotropically orienting, a step of radially or axially anisotropically orienting magnetic powder by applying a radial or axial anisotropic orientation magnetic field from the inner and outer peripheral sides of the cavity And a step of subsequently applying a multipolar anisotropic orientation magnetic field from the outer peripheral side of the cavity to partially orient the magnetic powder in a multipole anisotropic orientation. Production method.