JPS6047409A - Manufacture of anisotropic composite magnet - Google Patents

Abstract

PURPOSE:To improve production efficiency by using a mold for injection molding having a plurality of molding spaces, in which magnets for generating magnetomotive force are provided on outside of yokes, and permanent magnets for forming repulsion magnetic circuit are provided between the yokes. CONSTITUTION:A mold has a plurality of cavities 51-54 inside of a base 7 made of soft magnetic material, the cavities being provided with magnetic cores 61-64, respectively, inside thereof. Permanent magnets 11 and 12 for generating magnetomotive force and yokes 31, 32 are placed at the positions corresponding to the magnetic poles on the periphery of the cavity 5. Between the yokes, permanent magnets 21 and 22 are placed for forming repulsion magnetic circuit. Further, non-magnetic spacers 41 and 42 are placed outside of the magnets 21 and 22. The cavities 52-54 are also surrounded by a similar structure to that of the cavity 51. Mixture mainly consisting of ferromagnetic powder and thermoplastic resin is injection molded in the mold. The peripheral surface of the molded body thus obtained is magnetized in the same direction with the orientation by the magnetic field. Thus, the production efficiency can be improved.

Description

[Detailed Description of the Invention] The present invention is a method for manufacturing an anisotropic composite magnet in which a mixed material mainly composed of ferromagnetic powder and a thermoplastic resin is injection molded into a mold in a magnetic field to impart magnetic yellowing. Regarding.

In recent years, ferromagnetic powders such as ferrite powders and rare earth cobalt powders have been used in the fields of small motors, sensors, generators, etc.
Anisotropic composite magnets obtained by injection molding in a magnetic field a hybrid material mainly composed of plastic resin are attracting attention and are being put into practical use.

To manufacture this anisotropic composite magnet, conventionally a magnetizing coil connected to a magnetizing power source was installed inside a mold made of a combination of soft magnetic materials and non-magnetic materials (for example, in Japanese Patent Publication No. 58-140
4 (see Publication No. i), or it is common to provide anisotropy by installing a magnetizing coil outside the mold and applying electricity to the magnetizing coil to excite a magnetic field.

However, when manufacturing an anisotropic composite magnet using this type of mold, the equipment becomes expensive and large, and there are the following problems.

The above-mentioned composite magnets used in small motors, etc. are ring-shaped magnets that have anisotropy in the radial direction, and some have two symmetrical poles in the radial direction, and others have multipole anisotropy with 4 or more poles. There are two main types of magnets, but in any case, it is extremely difficult to produce multiple magnets, and in particular, it is impossible to produce multiple ring-shaped magnets with multipolar anisotropy, resulting in low productivity. was there.

Furthermore, as described in JP-A-56-69805, for example, in order to obtain a multipolar anisotropic composite magnet with inexpensive equipment, a magnetic field is applied by a permanent magnet placed in a mold. Magnetic field orientation has also been proposed. However, in the case of levers, it is possible to produce multiple pieces, but the magnetic circuit is equipped with a permanent magnet at a position corresponding to the magnetic pole part close to the molding space, and a metal plate is used to prevent disturbance of the magnetic field formed by the permanent magnet. Since only non-magnetic materials were used for the manufacture,
There is a problem that sufficient anisotropy cannot be achieved.

An object of the present invention is to provide a method for manufacturing an anisotropic composite magnet that eliminates the problems of the prior art described above and can efficiently produce a composite magnet with high performance bipolar or multipolar anisotropy using inexpensive equipment. It is to provide.

The method for producing an anisotropic permanent magnet of the present invention involves injection molding a mixture mainly composed of ferromagnetic powder and thermoplastic resin into a mold while applying a magnetic field, and applying the magnetic field to the outer peripheral surface of the obtained molded body. In the manufacturing method of an anisotropic composite magnet magnetized in the same direction as the orientation according to A mold is provided in which a yoke is installed, a permanent magnet for generating magnetomotive force is installed on the outside of each yoke, and a permanent magnet is provided in an adjacent yoke IW to form a repulsive magnetic circuit between the permanent magnets. It is characterized by the fact that it was used.

The details of the present invention will be explained below with reference to the drawings.

FIG. 1 is a sectional view showing an example of a mold used in the present invention,
Figure 2 is a perspective view of a permanent magnet incorporated into the mold shown in Figure 1;
FIG. 6 is a sectional view showing another example of the mold used in the present invention, and FIG. 4 is a perspective view of a permanent magnet incorporated into the mold shown in FIG.

First, in FIG. 1, this mold is used to manufacture a symmetrical bipolar ring-shaped magnet, and has a plurality of (four in the figure) cavities 5 inside a pace 7 made of a soft magnetic material. , ~54, and a magnetic core 6, ~64 is installed inside each cavity. Also capacity 6, +62+68 and 6. Permanent magnets 1 for generating magnetomotive force are placed at positions corresponding to the magnetic poles around the
1 and 1. ．． 1s and 14.1. and 1° and 17 and 1. and a yoke 3 made of a soft magnetic material to effectively converge the magnetic flux lines generated from the permanent magnet into the cavity. and 3□
, 33 and 3. , 3. and 36 and 67 and 36 are installed. Moreover, between each yoke, there is a permanent magnet 2. magnetized as shown in FIG. and 2. , 2. and 2. , 2. , 26, 27, and 2+ are installed, and each permanent magnet 2. Nonmagnetic spacers 4 and 48 are installed outside of 28, respectively.

According to the above mold, since a plurality of cavities are provided in the mold, it is possible to obtain a plurality of molded bodies at the same time, and the magnetic flux from the permanent magnet can be effectively converged within the molding space. 6000~aoo which is necessary for anisotropy without using a conventional magnetic field power supply or magnetization coil.
An orientation magnetic field of approximately o□e can be easily obtained.

Next, in Fig. 6 (the same 1 geometrical parts as in Fig. 1 are indicated by the same reference numerals), this mold is for manufacturing an anisotropic ring-shaped magnet with a symmetry of 44 f&, and is made from a soft magnetic material. There are two cavities inside the base 7. E.5 and 5.
Each cavity has a magnetic core 6,
,6. is installed. Also cavities 51 and 5
．． Permanent magnets are placed at positions corresponding to the magnetic poles around the `` `` to generate magnetomotive force, respectively. T'41
13 and 14 + 16 + 16 + 1? , a yoke 51 r 51 + made of a soft magnetic material to effectively converge the magnetic flux lines generated from the permanent magnet into the cavity.
53 + 54 and 'II + 36 + 37 +
311 is installed. In addition, the space between each yoke is magnetized as shown in Fig. 4 in order to substantially eliminate magnetic flux short-circuiting between adjacent permanent magnets 5 of the permanent magnet group (arrows in the figure indicate magnetization directions). ) Trapezoidal permanent magnet 2. ,2
2...28 are installed.

With the above-mentioned mold, a plurality of molded bodies can be obtained with a single mold, and the orientation magnetic field necessary for anisotropy can be easily obtained by the magnetic circuit including the permanent magnet.

In each of the above molds, the permanent magnet that is the source of magnetomotive force is a ferrite magnet, an alnico magnet, a Fe-Cr-
Co magnet, rare earth cobalt magnet, pt-(:'o magnet,
Various known permanent magnets such as Mn-Al-C magnets can be used, but for practical purposes, ferrite magnets, Fe-Cr-Co
It is desirable to select from magnets and rare earth cobalt magnets. In addition, permanent magnet 1. , 1. ... and permanent magnet 2
．． , 2. ... may use permanent magnets made of the same material or different materials.

In the above explanation, we have talked about manufacturing a ring-shaped magnet with two or four poles, but the number of magnetic poles is not limited to this, but six or more types are possible, and the number of cavities is not limited to two or four. Needless to say. Further, the shapes and dimensions of the permanent magnets, yokes, etc. used in the mold may be appropriately set according to the required magnetic properties, the number of magnetic poles, and the shape and dimensions of the product using an analytical method such as the finite element method.

In the present invention, an anisotropic composite magnet is obtained using the above-mentioned mold, for example, in the following manner.

First, as raw materials, B (ferrite powder such as L7 elite or Sr ferrite, alnico magnet powder,
Prepare a mixture of i”e -Cr-co magnet powder or rare earth cobalt magnet powder and thermoplastic resin (one or more types) such as styrene-butadiene copolymer, ethylene-vinyl acetate copolymer, polyethylene, polyamide, etc. However, the amount of ferromagnetic powder blended is 60% by weight from the viewpoint of magnetic properties.
or more (more preferably 80% by weight or more). In addition to these raw materials, a small amount (several percent by weight) of a lubricant such as polyethylene or calcium stearate may be added to improve moldability. For this purpose, additives such as organosilicon compounds or organotitanate compounds may be added.

Next, this mixed raw material is put into an injection molding machine having the above mold, molded in a magnetic field, and then cooled and solidified. The obtained compact is magnetized in the same direction as the anisotropic direction, either as it is or after machining, to obtain an anisotropic composite magnet.

Example 1 Ferrite powder (B2O.6Fe2.
Os ) 8.5 Kf with polyamide resin (nylon 6;
Product name) Add 15Kg and use a batch kneader to process about 2
The mixture was kneaded at a temperature of 40C. A commercially available injection molding machine (5AV6 manufactured by Yamagou Seiki Co., Ltd., manufactured by Sangei Seiki Co., Ltd.) equipped with the mold shown in Fig.
0-52 mold), injected into the mold at a temperature of 270C and a pressure of 70 yen, and then cooled and solidified.

In this case, the permanent magnets 11 to 18 are 5-Co rare earth cobalt magnets (Br -85000, IHC-8
,00 mouths Oe, (BH)%cLz -17,5MG
O6) and permanent magnets 2I to 28 are Fe-Cr-
co magnet (Br・-1!1500G, +Hc = 6
5000e l(BH)maw -5,5MGOe)
using yokes 31-5. And the base 7 is made of SS material, and the spacer 4. Using stainless steel as ~48,
The dimensions of cavities 51 to 540 were 30 tan φ x 20 tone φ x 30 bait.

As a result of subjecting the outer circumferential surface of the obtained ring-shaped compact to bipolar phantom magnetization, an anisotropic composite magnet having good magnetic properties as shown in FIG. 5 was obtained.

Example 2 Rare earth cobalt magnet powder [5-(Co
o, aa Feo, 2s Cuo, oy Hfo-ox
)? -1:) Polyamide resin (nylon 12: trade name) o, 5 icp was added to 92 Kf and kneaded at about 24 DC using a batch kneader. This kneaded material was put into an injection molding machine similar to that of Example 1 equipped with a mold shown in FIG. 3, injected into the mold at a temperature of 270 C and a pressure of 70 υ, and then cooled and solidified.

In this case, the mold includes permanent magnets 11 to 1. as 20w
nx iOgx S□coat with dimensions of 10mm
System permanent magnet (Br-9200G, +Hc-asoooe
, (BH)max-22M(30e).

Permanent magnets 21-2. As a ferrite magnet (13r-
5800G, 1Hc-24000e, (BH) ma
w-5,5MGOe), SS material is used for the yokes 6 to 38 and the base 7, and the capacity 5. , 5
．． The dimensions were set to 30 + nm x 20 mm x 60 mm.

As a result of subjecting the outer peripheral surface of the obtained ring-shaped compact to four-pole symmetrical magnetization, an anisotropic composite magnet having good magnetic properties as shown in FIG. 6 was obtained.

As described above, according to the present invention, a high-performance anisotropic composite magnet can be obtained with inexpensive and small-sized equipment and with high productivity.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a mold used in the present invention,
Figure 2 is a perspective view of a permanent magnet incorporated into the mold shown in Figure 1;
FIG. 3 is a sectional view showing another example of the mold used in the present invention, FIG. 4 is a perspective view of a permanent magnet incorporated into the mold shown in FIG. 3, and FIGS. FIG. 3 is a diagram showing the surface magnetic flux density distribution of an anisotropic composite magnet manufactured using the molds shown in FIGS. 1 and 3. FIG. 11-1. ．． 2. ~2. ...Permanent magnet, 6, ~36・
...York, 41-4. ...Nonmagnetic spacer, 5I-54...Cavity, 6, -64...Magnetic core.

Claims (1)

[Claims] 1. A mixture mainly composed of ferromagnetic powder and thermoplastic resin is injection molded into a mold while applying a magnetic field, and the outer peripheral surface of the obtained molded body is oriented in the same direction as the orientation caused by the magnetic field. In the method for manufacturing an anisotropic composite magnet which is magnetized, the mold has a plurality of molding spaces, and each molding space has a yoke provided at a position corresponding to a magnetic pole portion around the molding space, and the yoke A gold layer is used, in which a permanent magnet for generating magnetomotive force is installed on the outside of the yoke, and a permanent magnet is provided between adjacent yokes to form an anti-flame magnetic circuit between the permanent magnets. Wooden method of anisotropic composite magnet. 2. Ferrite magnet, F as a permanent magnet for generating magnetomotive force
The method for manufacturing an anisotropic composite magnet according to claim 1, characterized in that one selected from e-Cr-Co magnets and rare earth cobalt magnets is used. 3. The method for manufacturing an anisotropic composite magnet according to claim 1, characterized in that the molding space is cylindrical.