WO1991001562A1

WO1991001562A1 - Anisotropic plastic-bonded magnet

Info

Publication number: WO1991001562A1
Application number: PCT/JP1990/000827
Authority: WO
Inventors: Yoshihiko Matsuyama
Original assignee: Yuugen Kaisha Kanex
Priority date: 1989-07-24
Filing date: 1990-06-26
Publication date: 1991-02-07

Abstract

Hard ferrite magnetic powder of, e.g., barium ferrite or strontium ferrite, or rare earth magnetic powder of the Sm-Co or Nd-Fe-B is crystallized in a direction of crystal axis (C-axis) so that it may have the aspect ratio of the length of the crystal axis (C-axis) to the length of crystal face (C-plane) of 1:1 to 1:5. The crystalline magnetic powder possesses the effects of crystalline anisotropy and shape anisotropy. Three kinds of magnetic powders, i.e., a magnetic powder of 3 to 5 mν (0.05 to 0.1 mν) having the effects of crystalline anisotropy and shape anisotropy as a matrix, a magnetic powder of 1 to 3 mν (0.03 to 0.05 mν), and a magnetic powder of smaller than 1 mν (0.03 mν), are mixed together at a ratio that gives desired magnetic properties. The mixed powder may or may not be surface-treated with a silane coupling agent. This powder is then mixed with a small amount of a plasticizer and a parting agent, kneaded together with a thermoplastic resin or a thermosetting resin, and then pelletized. The pellets have a higher residual magnetic flux density (Br) and a smaller coercive force (Hc) than those of the general ones. Further, a rare earth permanent magnet such as SmxCoy (Sm1Co5, Sm2Co17), Nd-Fe-B is buried in a metal mold, and is anisotropically oriented during the molding. Then, the pellets are injection-molded or compression-molded using a metal mold for polar anisotropic plastic magnet that has a coil wound in the metal mold to form the polar anisotropy as well as to effect the magnetization in the same metal mold, and to remagnetize the buried permanent magnet that is demagnetized.

Description

Akira Itoda

Technical field of polar anisotropic plastic bonded magnet

The present invention relates to a polar anisotropic mold having a magnetizing function of a plastic magnet and a magnetic powder or hard ferrite powder.

N d — F e — B-based magnetic powder or S m — Co-based magnetic powder has been improved in shape and a combination of three types of magnetic powders of different sizes has resulted in a conventional flywheel. Height not seen with plastic magnets or Nd-Fe-B plastic magnets or Sm-Co plastic magnets Proposal of a polar anisotropic plastic magnet manufactured with a plastic magnet material that has the highest energy and has a high residual magnetic flux density and is suitable for this mold. About. Background art

Conventionally, in the case of a flat plastic magnet

After kneading the strontium ferrite or barium ferrite with a small amount of plasticizer and release agent, knead it with the resin. By using this pellet, injection molding in a magnetic field, or shrinking molding in a magnetic field, a fly plastic bonded magnet can be formed. It was being processed. However, in the conventional stage, the residual magnetic flux density, which is the magnetic property, is from 1,700 Gauss to 1,800 Gauss, and it is difficult to further improve the property. Was.

Also, in order to make this residual magnetic flux density close to the residual magnetic flux density of the sintered X-light magnet, the above-mentioned flat plastic bonded magnet is formed after molding. Then, a method was taken to evaporate the resin and approach the microstructure of the ferrite sintered magnet.

However, by evaporating the resin in this way, the mechanical strength was reduced, and the result was that the magnet became more brittle than the burned magnet.

In the case of rare earth plastic magnets, Nd-Fe-B or Sm-Co magnetic powder is mixed with a small amount of plasticizer and mold release agent, kneaded with resin, and then the pellet is removed. Rare earth plastic bonded magnets have been processed by injection molding in a magnetic field or compression molding in a magnetic field.

However, at the conventional stage, the magnetic characteristics BHnax and Br are limited to the characteristic values shown in Table 1, and it is difficult to further improve the characteristics. It was difficult.

Table 1

B H nax B r

Injection molding 4 MGO e 4 500 G

(Magnetic isotropic)

For compression molding 1 5 IGO e 8 5 0 0 G

(Magnetic anisotropy)

In order to bring the maximum energy product (BH Max) and residual magnetic flux density (Br) closer to the characteristics of each rare-earth sintered magnet, the above-mentioned rare-earth plastic box is used. After the forming process of the magnet, the resin was evaporated to make it close to the structure of the rare earth sintered magnet.

However, by evaporating the resin in this way, the mechanical strength was reduced, resulting in the brittleness of the rare earth magnet.

Further, in the conventional technology, the polar anisotropy of 10 poles as shown in Fig. 1 of the above-mentioned flat plastic magnet or rare earth plastic magnet is used. When a rotor having a magnetic field is manufactured, it is composed of a molding die as shown in FIG. 2 and 10 rare-earth magnets having the highest magnetic energy are embedded therein. After forming a polar anisotropic rotor with such a mold, the magnet was formed using a magnetizing coil with a rotor alignment function. Disclosure of the invention

Conventionally, as described above, methods for improving the residual magnetic flux density of a flat plastic bonded magnet include magnetic and mechanical performances. There was nothing that could be produced stably.

Therefore, by utilizing the effects of both the crystal anisotropy and the shape anisotropy of the magnetic powder alone, the magnetic characteristics are improved, and mechanically, the conventional plastic bob is used. In order to achieve the same quality as an indented magnet, there is a need to provide a magnet that does not change the filling rate of magnetic powder.

The solution is to maximize the crystal anisotropy effect and shape anisotropy effect in order to improve the magnetic properties of the magnetic powder.

That is, the crystal powder of the strontium ferrite or the magnetic powder of the rhodium ferrite is grown in the direction of the crystal axis (C axis), and the crystal face is formed. (C plane) The aspect ratio of the length of the crystal axis (C axis) to the diameter is 1; 1 to 1; 5 and the magnetic anisotropy It has the effect and the shape anisotropy effect.

The magnetic powder of 3 to 5 m having the crystal anisotropy effect and the shape anisotropy effect is used as a base material, and the magnetic powder of l to 3 m ju, which is smaller in shape than the magnetic powder, is used. Powder and magnetic powder of less than lm are mixed according to the desired magnetic properties and surface-treated with a silane coupling agent, or without surface treatment, and with a small amount of plasticizer. A molding agent is added and kneaded with 8 to 21% thermoplastic resin or 4 to 5% thermosetting resin to form a pellet.

In addition, mechanical molding with a high residual magnetic flux density can be achieved by injection molding or compression molding in a polar anisotropic magnetic field or magnetic field, or by injection molding or a polar anisotropic magnetic field. It provides a strong plastic bonded magnet.

In particular, in the present invention, the magnetic material is excited by a polar anisotropic magnetic field and molded, so that the content of the magnetic powder is reduced to about 80%, and the iHc of the magnetic material pellet is relatively small. The present invention has been made by using any of them.

Also, as described above, conventionally, N d _ F e —B system or

There are two ways to improve the magnetic properties (BH Max, Br) of plastic bond magnets of the Sm-Co series, both in terms of magnetic and mechanical performance. However, there was nothing that could be produced stably. Therefore, by utilizing the effects of both the crystal anisotropy and the shape anisotropy of the magnetic powder alone, the magnetic properties are improved, and mechanically, a conventional plastic bond is used. Filling ratio of magnetic powder is set to be equivalent to that of a dead magnet.

It is intended to provide a product having a concentration of 80 nt% to 90 nt%.

That is, Nd_Fe—B-based magnetic powder or Sm_Co-based magnetic powder is grown in the crystal axis (C-axis) direction, and the crystal axis (C-plane) diameter is determined by the crystal axis (C-plane) diameter. The magnetic powder has a crystal anisotropy effect and a shape anisotropy effect by machining the length ratio (C-axis) to 1; 1 to 1; 5 It is a thing.

In the case of magnetic powder produced by the sintering method, the magnetic powder having a crystal anisotropy effect and a shape anisotropy effect of 3 to 5 mja is used as a base material. Three types of magnetic powder, l to 3 m / i and smaller than lm / i, which are smaller in shape than the magnetic powder, are mixed in proportions according to the desired magnetic properties. Surface treated with a ringing agent or without surface treatment, add a small amount of plasticizer and release agent, and add 8 to 20 * t% of thermoplastic resin or 4 to 5, It is kneaded with a thermosetting resin of% to make a pellet.

When manufactured by the high-speed solidification method, a magnetic powder of 0.05 to 0.1 m # having the crystal anisotropy effect and the shape anisotropy effect is used as a base material. In addition, the desired magnetic properties of a magnetic powder having a smaller shape of 0.33 to 0.05 m # and a magnetic powder of 0.03 HI # or less than this magnetic powder are desired. And then surface-treated with a silane coupling agent, or without a surface treatment, add a small amount of plasticizer and molding agent, and add 8 to 20% thermoplasticity. It is kneaded with a resin or 4 to 5 thermosetting resin to make a pellet.

In addition, mechanical molding with a high residual magnetic flux density can be achieved by injection molding or compression molding in a polar anisotropic magnetic field or a magnetic field. Offers strong plastic bonded magnets In particular, in the present invention, when magnetized with a polar anisotropic magnetic field and molded into a thermoplastic resin, the content of the magnetic powder is set to 890 wt%, and the magnetic material pellet is formed. The effect of the present invention was improved by using a relatively small value of iHc.

In addition, in the conventional example of a die for forming these flat plastic magnets or rare earth plastic magnets in a polar anisotropic manner, the forming is repeated. Each time it is returned, there is a mold temperature of 100 to 130¾, and a high temperature near 300 ° is applied, so that the embedded permanent magnets are demagnetized and anisotropic. It is known that the sexual orientation effect decreases. Therefore, the conventionally embedded permanent magnets are removed from the mold, re-magnetized, and assembled into the mold so that the anisotropic effect can be stably maintained. Yes. As shown in Fig. 3, one or several turns are required inside the mold to solve such problems and further increase the productivity of the rotor. The coil is retracted and the coil is excited with a pulse current of 10,000 amperes or more by the magnetizing power supply (power supply such as capacitor charging and discharging). is there .

Magnetization by this excitation is performed in the cooling stage after the injection compression and pressurization in the forming stage.

As a result, magnetization can be performed during the molding operation (during injection molding or compression molding), and the product can be taken out as before, and the magnetized coil can be used. Because of the polar anisotropy that had been done, it was possible to accurately magnetize the poles at the same time as molding without the need for extra work such as pole alignment. . BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 is a side view showing a rotor with 10 poles of polar anisotropy.

Figure 2 shows the structure of a conventional polar anisotropic rotor mold.

FIG. 3 is a structural diagram of a mold of the polar anisotropic rotor according to the present invention. FIG. 4 is an explanatory diagram showing a crystal structure of the magnetic powder of the graphite according to the present invention. Fig. 1 is a diagram schematically showing an arrangement of magnetic particles of a polar plastic magnet formed according to the present invention and formed by polar anisotropy. D Fig. 6 is an explanatory diagram showing the crystal structure of the rare earth magnetic powder according to the present invention.

FIG. 7 is a diagram schematically showing an arrangement of magnetic particles of a rare earth plastic magnet formed by polar anisotropy according to the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will be described in more detail with reference to the accompanying drawings.

FIG. 4 is a graph showing the relationship between the diameter of the C-face diameter D of the magnetic powder of the strontium filament and the magnet powder of the present invention. This shows the magnetic powder structure in which the ratio (axial ratio) of the shaft length L is from 1; 1 to 1; 5.

By adopting such a magnetic powder structure, the magnetic powder particles grow in the crystal axis direction, and a crystal anisotropic effect occurs on the crystal axis.

Furthermore, the C-axis is longer than the C-plane, so that the shape anisotropy effect occurs in the crystal anisotropy direction, and the crystal anisotropy effect further increases An anisotropic effect is added.

The size of the long part of the magnetic powder described above is 3 to 5 mi, and three types of small magnetic powder of l to 3 m / i, medium and lm / i or less are required. Mix according to the desired magnetic and mechanical properties.

It is desirable that the medium-sized magnetic powder and the small-sized magnetic powder have the same crystal anisotropy and shape anisotropy as the large-sized magnetic powder. In the case where it cannot be performed, it is acceptable that neither crystal anisotropic effect nor shape anisotropic effect is provided.

The surface of the mixed magnetic powder is treated with a silane coupling agent of 0.5 to 1.5% by weight and / or a titanium coupling agent,

1.0-2.0% plasticizer and / or

0.1 to 0.5 * t% of release agent and 8 to: L2 * t% of thermoplastic resin or 3 to 4 wt% of thermosetting resin and kneading And turned it into a pellet. As a result of injection molding in a magnetic field using a pellet obtained by kneading the strong carbon powder and thermoplastic resin having the above-described configuration, the Although the surface magnetic flux density was 170 Gauss,

It reached 200 Gauss.

In particular, in order to enhance the anisotropy effect in a magnetic field, the residual magnetic flux density (Br) of the stronium film X-light has conventionally been 2276 Gauss. Is set to 3100 Gauss, and the intrinsic coercive force (iHc) is conventionally set to 311 O Oested as 264 O Oested, and H as the magnetic powder. A relatively small one was used.

In the above description, the plasticizer and the release agent are added at the time of kneading the magnetic powder and the resin. However, these may be omitted as necessary.

Fig. 5 shows the arrangement of the magnetic powder inside the plastic magnet when polar anisotropic magnetization molding was performed with the N pole 18 and the S pole 19 as the magnetic poles. O

As shown in Fig. 4, 3 to 5 m (large) dust particles 15, medium-sized magnetic particles 16 to 1 to 3 mi, and magnetic particles 17 below Im are magnetic poles at N pole 18 and S pole 19. They are arranged neatly in the direction of the internal magnetic field.

There is no arrangement of magnetic particles at neutral point 20.21.

Those having a surface magnetic flux density of 2000 Gauss showed a magnetic particle arrangement as shown in FIG.

Fig. 6 shows the ratio of the C sleeve length L to the C face diameter D of the Nd_Fe-B-based magnetic powder or Sm-Co-based magnetic powder according to the present invention ( The ratio of the magnetic powder is from 1; 1 to 1; 5.

By adopting such a magnetic powder structure, the magnetic powder particles grow in the crystal axis direction, and a crystal anisotropic effect occurs in the crystal axis direction. Furthermore, the C-axis is longer than the C-plane, so that the shape anisotropy effect occurs in the same direction as the crystal anisotropy direction. Further, a shape anisotropy effect is added. The size of the long part of the magnetic powder described above is

When manufactured by the sintering method,

4 to 5 m #, and medium to l to 3 m ^

l m // Mix the following three types of small magnetic powders in an arbitrary ratio according to the required magnetic and mechanical properties.

Also, when manufactured by the high-speed solidification method,

0.05 to 0.05 lm /, and also requires three types of small magnetic powder of 0.33 to 0.05 m / i, medium size and 0.03 mj ^ or less. Mix in an arbitrary ratio according to the magnetic and mechanical properties.

It is desirable that the medium and small magnetic powders have the same crystal anisotropy and shape anisotropy as large-sized powder, but they can be processed due to the manufacturing method. If they do not exist, it is acceptable if they do not have the crystal anisotropy effect and the shape irregularity effect.

The above-mentioned mixed magnetic powder is surface-treated with 0.5 to 1.5 nt% of a silane coupling agent and / or a titanium coupling agent,

1.0-2.0, t% plasticizer and / or 0.1-0.5% of mold release agent, add 8-21% of thermoplastic resin or It is kneaded with 3 to 4 * t% of thermosetting resin to form a pellet.

A pellet obtained by kneading the Nd-Fe-B-based magnetic powder or the Sm-Co-based magnetic powder and the thermoplastic resin or the thermosetting resin having the above-described configuration is used. However, as a result of injection molding or compression molding in a magnetic field, an improvement of 10 to 20% of the conventional surface magnetic flux density was observed.

In particular, in order to enhance the anisotropy effect in a magnetic field, the residual magnetic flux density (B r) is large and unique among Nd-Fe-B-based magnetic powder or Sm-Co-based magnetic powder. Those with relatively low holding power (iHc) were used.

In the above description, the plasticizer and the molding agent are added at the time of kneading the magnetic powder and the resin, but these may be removed as necessary.

Fig. 7 shows the arrangement of magnetic powder inside the plastic magnet when polar anisotropic magnetization molding was performed using the N pole 25 and the S pole 26 as the magnetic S. In _Q

Large magnetic powder 22 of 3 to 5 m / i (0.05 to 0.05 lm / i) and l to 3 m / (0.03 to 0.05 m //) shown in Fig. 6 Magnetic particles 23 and magnetic particles 24 of 1 mβ (0.03 m ju) or less are arranged neatly in the direction of the internal magnetic field of the magnetic pole at the negative pole 25 and the south pole 26. ing . There is no arrangement of magnetic particles at neutral points 27 and 28. The one with improved residual magnetic flux density by 10 to 20% showed a magnetic particle arrangement as shown in Fig. 7.

FIG. 3 shows the structure of a polar anisotropic co-magnetizing mold according to the present invention. Permanent magnets 2 made of rare earth magnets are arranged around the cavity 1 in a number corresponding to the number of poles of the product.

The permanent magnets 2, 3, and 4 are arranged in the non-magnetic material 14 so that the magnetic pole (N pole) 5 comes to the cavity 1 side. The N pole and the S pole are alternately arranged toward the coil, and the coil 6 is arranged between the permanent magnet 2 and the permanent magnet 3 so that the direction of the current flowing through the coil is permanent. The wiring is such that the magnetic pole 5 of the magnet 2 is set to the N pole. Since coil 6 is wound as shown in Fig. 3, an N pole is generated at the magnetic pole on the cavity side of the permanent magnet 2, and an S pole is generated at the permanent magnet 3. Then, the permanent magnet is excited.

By supplying current from a power source such as a capacitor and discharge to the coil at the cooling stage after injection compression in the injection molding process, the mouth of the molded product can have a uniform polarity. It was possible to accurately magnetize without having to match.

Since the coil is wound in this way, the respective permanent magnets for pole anisotropy 3, 4 are alternately excited with N, S, and N poles, respectively. It also has the effect of re-magnetizing the permanent magnet for pole anisotropy. A magnetic field can be applied even in the injection compression / pressurization process of injection molding, and the anisotropic effect can be improved.

Figures 2 and 3 show the structure of the mold, and 12 shows the protruding pins.

13 indicates the mold parting line, and 14 indicates the permanent magnets 2, 3, 4 The figure shows the non-magnetic material part of the mold for fixing the mold.

15 'indicates the power supply terminal of the excitation coil 6.

Fig. 1 shows a 10-pole rotor 7 molded with polar anisotropy.

NS 8, 10-industrial applicability showing one embodiment with S poles 9, 11 ...

1 ') With the magnetic powder composition as in the present invention, the molded plastic plastic magnet has a magnetic flux density improved by 10% as compared with the conventional one. I was able to do it.

2) The large, medium, and small magnetic powders of the present invention increase the density of each other in the magnets, and at the same time, combine with the surface treatment agent of the magnetic powders due to the effect of the modified 12-iron. As the force increased, it was possible to produce a plastic magnet that would not break at all, even if the press-fit for the shaft was about 0.1 mm. 3) Molded by using the magnetic powder composition as in the present invention.

Nd-Fe-B plastic magnets or Sm-Co plastic magnets have a 10% to 20% improvement in magnetic flux density compared to conventional magnets I was able to make it happen.

4) The present invention takes out the product by incorporating the coil into a conventional polar anisotropic mold in which a rare earth permanent magnet is embedded, and magnetizes it with a magnetizing coil with pole matching. Since the magnets can be magnetized with high precision during molding with a molding machine, productivity has improved. Furthermore, since the demagnetization of the rare-earth magnet for polar anisotropy can always be prevented, the maintainability of the mold has been significantly improved. Extremely effective because the coil-embedded mold can be applied to polar anisotropic products other than the rotor, which can improve productivity and reduce manufacturing costs. It is an important means.

Claims

Scope of the claim: The length of the crystal axis (C axis) relative to the diameter of the crystal face of the normium ferrite or the stronium ferrite Magnetic powder with a crystal axis length of 4 to 5 m〃, a magnetic powder with a particle diameter of l to 3 m〃, and a particle diameter of 1; 1-1; 5; For the three types of magnetic powders of lm ju or less, mixed magnetic powders were prepared by mixing the three types of magnetic powders in an arbitrary ratio, and the mixed magnetic powders were mixed in a range of 0.5 to 1.5 * t%. Surface treatment with a silane coupling agent or titanium coupling agent of this type, or without any surface treatment,

1.0 ~ 2.0 wt% plasticizer and

0.1 to 0.5

Knead with thermoplastic resin or thermosetting resin, and further produce pellets,

ί3 m C o γ ^ o m 1 C o 5, S ni 2 C o i 7

Nd_Fe_B rare earth permanent magnets are embedded in the mold,

Anisotropic orientation during molding

In addition, the coil is wound in the mold, and the same mold is used for both polar anisotropic molding and magnetization, and the effect of re-magnetization against demagnetization of the embedded permanent magnet is also achieved. Prepare a mold for polar anisotropic plastic magnets

A polar anisotropic plastic box characterized in that the pellet is injection-molded or compression-molded with the polar anisotropic plastic magnet mold. Dead magnet.

The aspect ratio of the length of the crystal axis (C-axis) to the diameter of the crystal plane of the Nd-Fe_B-based magnetic powder or Sm-Co-based magnetic powder is 1; 1 ~ 1; 5 and

According to the sintering method, the length of the crystal axis in the case of the manufactured magnetic powder is 3 to 5 m // Magnetic powder with a powder diameter of l ~ 3 m / i, and

For the three types of magnetic powder, magnetic powder with a particle diameter of l m jti or less,

In addition, a magnetic powder in which the crystal axis length of the manufactured magnetic powder is 0.05 to 0.1 πι / ί by the high-speed solidification method,

A magnetic powder with a particle size of 0.3 to 0.05 m / i,

For the three types of magnetic powders, one with a powder diameter of 0.3 m or less,

A mixed magnetic powder is prepared by mixing the three types of magnetic powder in an arbitrary ratio, and the mixed magnetic powder is mixed with 0.5 to 1.5 wt% of a silane coupling agent or titanium. Surface treatment with coupling ring

Or, without surface treatment

1.0 to 2.0 wt% plasticizer

0.1 to 0.5 irt% of release agent and

Kneaded with thermoplastic resin or thermosetting resin to produce pellets,

S ni x C oy (S mi Co ₅ , S m ₂ Coi ₇ ),

N d — Fe-B rare earth permanent magnets are embedded in the mold,

During molding, anisotropic orientation is

In addition, the coil is wound into a mold, and the same mold is used for both polar anisotropic molding and magnetization, and the effect of re-magnetization against demagnetization of embedded permanent magnets is also achieved. Prepare a mold for polar anisotropic plastic magnets

The polar anisotropy according to claim 1, characterized in that the pellet is injection-molded or compression-molded with the mold for a polar-anisotropic plastic magnet. Plastic bonded magnet.