JPH09162055A - Method for manufacturing anisotropic sintered magnet - Google Patents

Abstract

(57) [Abstract] SOLUTION: Magnetic rubber portions 1a, 2a of a lid portion 1 and a bottom portion 2
The present invention relates to a method for producing an anisotropic sintered magnet, characterized in that at least a part of the horizontal cross-sectional area thereof is smaller than the area of the upper and lower surfaces of the permanent magnet powder p filled in the cavity g1 of the rubber mold g. [Effect] An anisotropic sintered magnet with little variation in residual magnetic flux density can be manufactured, and as a result, the manufacturing yield is improved.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a permanent magnet powder filled in a cavity of a rubber mold, which is oriented by applying a magnetic field and compression-molded to form a green compact of the permanent magnet powder. The present invention relates to an anisotropic sintered magnet manufacturing method for manufacturing an anisotropic sintered magnet by sintering a green compact.

[0002]

2. Description of the Related Art As anisotropic sintered magnets, ferrite magnets such as Ba ferrite type and Sr ferrite type magnets, RC
Rare earth magnets such as o type and R-Fe-B type (R represents a rare earth element containing Y) are widely used. In these anisotropic sintered magnets, the easy magnetization directions of the crystal grains having magnetism are aligned in a certain direction. Therefore, the easy magnetization directions of the crystal grains are in different directions. When the magnet is magnetized in the direction of easy magnetization, the value of the residual magnetic flux density is larger than that of the direction magnet, so that the maximum energy product can be increased. Further, as compared with a bonded magnet bonded with a resin or the like, the amount of the non-magnetic substance is small, so that the value of the residual magnetic flux density becomes large and the maximum energy product can be made large.

The above-mentioned anisotropic sintered magnet is generally manufactured as follows.

By applying an external magnetic field to the permanent magnet powders, the permanent magnet powders pulverized to almost a single crystal are aligned with the easy axis of magnetization of each permanent magnet powder in a direction parallel to the direction of the external magnetic field. At the same time, pressure is applied to compress and mold. Then, the compression-molded green compact is sintered under predetermined conditions to manufacture an anisotropic sintered magnet. Depending on the material, heat treatment is performed after sintering.

Recently, a technique has been developed for dramatically improving the properties of an anisotropic sintered magnet by using a rubber mold in the step of forming an anisotropic sintered magnet (for example, Japanese Patent Laid-Open No. 4-363010). issue). In this method, after filling the cavity of the rubber mold with permanent magnet powder, placing the rubber mold in the pulse magnetic field generating coil and applying the pulse magnetic field, the permanent magnet filled in the cavity of the rubber mold is filled. While orienting the powder,
A green compact in which the permanent magnet powder is oriented is molded by applying a compression pressure to the rubber mold filled with the permanent magnet powder in the direction parallel to the pulse magnetic field application direction.
The permanent magnet powder in the rubber mold is quasi-isotropically molded by the deformation of the rubber mold due to the compression pressure. By thus forming the permanent magnet powder in the rubber mold in a pseudo-isotropic manner, the orientation of the permanent magnet powder at the time of forming was improved, and as a result, it became possible to improve the residual magnetic flux density.

[0006]

However, Japanese Unexamined Patent Publication No.
No. 363010 is used to mold a green compact having a large size, particularly a green compact having a long dimension in the direction in which a magnetic field is applied, and when the green compact is sintered, the upper end of one sintered body The magnetic characteristics of the lower part and the lower part may deteriorate. For example, the obtained sintered body is cut into several equal parts in a plane perpendicular to the direction in which a magnetic field is applied, and the magnetic properties of each cut piece are measured. The magnetic flux on the surface of the magnet piece cut out from the different portion has a significantly different value between the front and back of the magnet piece. Such variations in magnetic properties make it difficult to control the magnetic properties of products,
In addition, the yield of the product is deteriorated. In order to solve this problem, the present applicant has proposed a method of improving magnetic property deterioration by arranging a rubber having magnetism above and below the permanent magnet powder filled in the cavity of the rubber mold. (Japanese Patent Application No. 7-276500).

An object of the present invention is to provide a method for manufacturing an anisotropic sintered magnet having improved magnetic characteristics as well as more reliably improving the above problems.

[0008]

In order to achieve the above-mentioned object, the present invention firstly provides at least one of the portions in contact with the upper and lower surfaces of the permanent magnet powder filled in the cavities of the lid and the bottom. The part is formed of a magnetic rubber part that is a composite of rubber and magnetic particles, and the side surface part is filled with permanent magnet powder in the cavity of the rubber mold formed of rubber that does not have magnetism. An anisotropic sintered magnet that is filled with magnet powder, applies a magnetic field to the rubber mold, and compacts the rubber mold to form a powder compact of permanent magnet powder, and then sinters the powder compact. At least a part of the horizontal cross-sectional area of the magnetic rubber portion of the lid portion and the bottom portion is smaller than the area of the upper and lower surfaces of the permanent magnet powder filled in the cavity of the rubber mold. Secondly, both the areas of the portions of the magnetic rubber portions of the lid portion and the bottom portion, which come into contact with the permanent magnet powder, are smaller than the areas of the upper and lower surfaces of the permanent magnet powder. Thirdly, the areas of the portions of the magnetic rubber portion of the lid portion and the bottom portion which come into contact with the permanent magnet powder filled in the cavities are both equal to the areas of the upper and lower surfaces of the permanent magnet powder. It is characterized in that it is large or larger and at least a part of the horizontal cross-sectional area of the magnetic rubber portion is smaller than the area of the upper and lower surfaces of the permanent magnet powder.

[0009]

[Examples] Generally, when a magnetic material is magnetized, magnetic poles appear at both ends of the magnetic material, and the magnetic flux inside the magnetic material has a large magnetic flux density in the central part of the magnetic material and the direction of the magnetic flux is uniform. However, the magnetic flux density at the end of the magnetic body is smaller than that at the center, and the direction of the magnetic flux is also non-uniform. In particular, such a decrease in magnetic flux density, nonuniformity, and disturbance in the magnetic flux direction are remarkable in the portion where the magnetic pole appears. A simulated representation of this situation is shown in FIG. Such a phenomenon also appears when a permanent magnet powder is filled in the cavity of the rubber mold and a magnetic field is applied, a magnetic pole is generated, and the magnetic field distribution of the permanent magnet powder filled in the cavity of the rubber mold is also shown. It is thought that it is like 1.

In addition, in order to apply a magnetic field to the permanent magnet powder, when the permanent magnet powder is arranged in the solenoid coil and the magnetic field is generated in the solenoid coil, the magnetic field itself is generated as shown in FIG. Is spread from the central part of the coil c toward the upper and lower ends, so that the disturbance in the magnetic flux direction at the end of the magnetic body becomes more remarkable. Since the magnetic poles are generated and the magnetic field distribution is disturbed in this way, the easy magnetization direction of the permanent magnet powder is directed toward the disturbed magnetic field distribution, which is considered to have caused the above-mentioned problems.

According to the present invention, there is provided a rubber mold in which a lid and a bottom are provided with a magnetic rubber having a horizontal cross-sectional area partially filled in a cavity of the rubber mold and having a cross-sectional area smaller than the vertical area of the permanent magnet powder. By using the orientation magnetic field, the disturbance of the magnetic field at the upper and lower ends of the solenoid coil is improved, and the magnetic pole appears on the surface of the magnetic rubber opposite to the surface in contact with the permanent magnet powder. It will not appear on the surface. Therefore, the decrease and non-uniformity of the magnetic flux density near the magnetic poles and the disturbance in the magnetic flux direction are concentrated on the magnetic rubber portion, and the permanent magnetic powder portion has a uniform magnetic flux density because the influence of the magnetic poles is alleviated. Moreover, the directions of the magnetic fluxes become parallel, and it becomes possible to suppress the disorder of the orientation.

In the present invention, by using the rubber mold, the orientation of the anisotropic sintered magnet is enhanced by the action and effect disclosed in Japanese Patent Laid-Open No. 4-363010, and the lid and bottom of the rubber mold are further improved. A magnetic rubber having a horizontal cross-sectional area smaller than the horizontal cross-sectional area of the permanent magnet powder filled in the cavity, which is the permanent magnet powder filling portion of the rubber mold, is arranged in at least a part of the rubber mold. Is placed at a position in contact with the permanent magnet powder filled in the cavity of the rubber mold to make the magnetic flux in the vicinity of the lid and the bottom parallel to the central part to suppress the variation in the orientation. is there. At this time, the anisotropic sintered magnet produced was sliced into five equal parts in a direction perpendicular to the magnet orientation direction to cut out magnet pieces, and the magnetic flux densities on the upper surface and the lower surface of the magnet pieces were calculated as Hall elements. The ratio of the surface magnetic flux density of the lower surface to the surface magnetic flux density of the upper surface (surface magnetic flux density of the lower surface / surface magnetic flux density of the upper surface) was 1.
000 ± 0.035, preferably 1.000 ± 0.0
It is desired to be in the range of 25.

Since the above-mentioned magnetic rubber portion (magnetic rubber portion) is a part of the rubber mold, it must naturally have the properties of rubber.
If this is not the case, the formability will be greatly deteriorated, and cracks, cracks, chips, etc. will likely occur in the resulting green compact. The magnetic rubber of the present invention is prepared by mixing magnetic particles and liquid rubber, pouring the mixture into a mold, and then curing the rubber. The saturation magnetization 4πIs of the magnetic rubber is adjusted by considering the saturation magnetization 4πIs of the magnetic particles and the mixing ratio of the magnetic particles and the rubber.

Therefore, the saturation magnetization 4πIs of the magnetic rubber used in the present invention is more preferable as it approaches the magnetization of the permanent magnet powder filled in the cavity of the rubber mold. As the magnetic particles used for the magnetic rubber, any substance may be used as long as it is a magnetic substance, but since the saturation magnetization 4πIs of the FeCo alloy powder particles is large, a magnetic rubber having a predetermined saturation magnetization 4πIs is produced. In doing so, the mixing ratio of the FeCo alloy powder particles can be reduced, and the properties of the magnetic rubber as a rubber are less likely to be impaired. Further, the FeCo alloy powder particles do not easily rust and do not oxidize even after long-term use, so that the magnetic properties of the magnetic rubber do not change with time.

Next, referring to FIGS. 3 and 4 which are vertical cross-sectional views of the rubber mold, at least one of a lid portion and a bottom portion as an example used in the method for producing an anisotropic sintered magnet of the present invention. A rubber mold in which a magnetic rubber is arranged in the section will be described. 3 and 4, g is a rubber mold having a cavity g1 filled with the permanent magnet powder p, 1 is a lid part, 2 is a bottom part, and 3 is a side of the cavity g1. It is a side surface portion arranged so as to surround the side. Further, 1 a is a magnetic rubber portion arranged on the lid portion 1 and 2 a is a magnetic rubber portion arranged on the bottom portion 2.

In the embodiment shown in FIGS. 3A and 3B, the magnetic rubber portion 1a of the lid portion 1 and the magnetic rubber portion 2a of the bottom portion 2 are provided in the cavity g1 as a permanent magnet powder filling portion. The areas of the portions in contact with the filled permanent magnet powder p are both smaller than the areas of the upper surface and the lower surface of the permanent magnet powder p filled in the cavity g1. And FIG.
The magnetic rubber portion 1a of the lid portion 1 and the magnetic rubber portion 2a of the bottom portion 2 of (a) are both formed in a columnar shape such as a columnar shape,
The magnetic rubber portion 1a of the lid portion 1 and the magnetic rubber portion 2a of the bottom portion 2 of FIG. 3B are both formed in an inverted trapezoidal shape whose horizontal cross-sectional area increases as the distance from the cavity g1 increases.

In FIGS. 4A and 4B, the lid portion 1
The areas of the magnetic rubber portion 1a and the bottom portion 2 of the magnetic rubber portion 2a in contact with the filled permanent magnet powder p are equal to or larger than the areas of the upper surface and the lower surface of the permanent magnet powder p filled in the cavity g1. Further, the horizontal cross-sectional area thereof is reduced in the trapezoidal shape with increasing distance from the cavity g1. The areas farthest from the cavity g1 of the magnetic rubber portion 1a of the lid portion 1 and the magnetic rubber portion 2a of the bottom portion 2 are both the cavity g as a permanent magnet powder filling portion.
It is smaller than the areas of the upper surface and the lower surface of the permanent magnet powder p filled in No. 1.

As shown in FIG. 3A, when the entire magnetic rubber portion 1a of the lid portion 1 and the entire magnetic rubber portion 2a of the bottom portion 2 are smaller than the area of the upper surface and the lower surface of the filled permanent magnet powder p. Further, as shown in FIG. 3B, the area of the portion of the magnetic rubber portion 1a of the lid portion 1 and the magnetic rubber portion 2a of the bottom portion 2 which are in contact with the filled permanent magnet powder p is the filled permanent magnet powder p. Is smaller than the area of the upper surface and the lower surface of the bottom surface, and the horizontal areas of the magnetic rubber portion 1a of the lid portion 1 and the magnetic rubber portion 2a of the bottom portion 2 increase with increasing distance from the surface in contact with the permanent magnet powder p. Can suppress the disorder of orientation due to the generation of magnetic poles.

For example, as shown in FIG. 5, the entire magnetic rubber portion 1a of the lid portion 1 and the magnetic rubber portion 2a of the bottom portion 2 are covered.
Is larger than the area of the upper surface and the lower surface of the filled permanent magnet powder p, when the magnetic field is applied, it is filled along the upper and lower edges g2 and g3 of the cavity g1 as the permanent magnet powder filling portion. The permanent magnet powder p attempts to move in the circumferential direction of the magnetic rubber portion 1a of the lid portion 1 and the magnetic rubber portion 2a of the bottom portion 2 which are larger than the areas of the upper surface and the lower surface of the filled permanent magnet powder p. The density of the permanent magnet powder p at the upper and lower corners of the molded green compact is reduced, and the density of the molded green compact becomes uneven. In addition, 4 is a pulse magnetic field generation coil for orienting the permanent magnet powder p.

In the embodiment shown in FIG. 3, the area (Sg) of the magnetic rubber portion 1a of the lid portion 1 and the magnetic rubber portion 2a of the bottom portion 2 in contact with the filled permanent magnet powder p.
Is equal to or smaller than the area (Sp) of the upper surface and the lower surface of the filled permanent magnet powder p, that is, Sp ≧ Sg, and the magnetic rubber portion 1a of the lid portion 1 and the magnetic rubber portion 2a of the bottom portion 2 are An example is shown in which the horizontal cross-sectional area increases with distance from the surface in contact with the permanent magnet powder p, or does not change.

In the embodiment shown in FIG. 4, the area (Sg) of the magnetic rubber portion 1a of the lid portion 1 and the magnetic rubber portion 2a of the bottom portion 2 in contact with the filled permanent magnet powder p.
Is equal to or larger than the area (Sp) of the upper surface and the lower surface of the filled permanent magnet powder p, that is, Sg ≧ Sp, and the magnetic rubber portion 1a of the lid portion 1 and the magnetic rubber portion 2a of the bottom portion 2 are The horizontal cross-sectional area of is smaller with increasing distance from the surface in contact with the permanent magnet powder p. By configuring in this way, the direction of the magnetic flux that tries to spread to the outside is
It is possible to correct the filled permanent magnet powder p in the direction along the vertical central axis, and improve the uniformity of the magnetic flux density and the magnetic flux direction.

The dimensions of the magnetic rubber portion 1a of the lid portion 1 and the magnetic rubber portion 2a of the bottom portion 2 are the minimum horizontal sectional area (Sg) of the magnetic rubber portions 1a and 2a, and the upper and lower surfaces of the filled permanent magnet powder p. When the ratio (Sg / Sp) of the area (Sp) of 1 is 1 or less, the excellent effect is exhibited.
As in (a) and (b), the permanent magnet powder p filled with the magnetic rubber portion 1a of the lid portion 1 and the magnetic rubber portion 2a of the bottom portion 2 is filled.
When the area (Sg) of the portion in contact with is smaller than the area (Sp) of the upper surface and the lower surface of the filled permanent magnet powder p, the above ratio (Sg / Sp) is 0.5 to 0.9. It is preferable.

Further, as shown in FIG. 4, the lid 1
Areas (Sg) of the magnetic rubber portion 1a and the bottom portion 2 of the magnetic rubber portion 2a in contact with the filled permanent magnet powder p are the upper and lower surface areas (Sp) of the filled permanent magnet powder p.
Equal to or larger than, and the magnetic rubber portion 1a of the lid portion 1
And the horizontal cross-sectional area of the magnetic rubber portion 2a of the bottom portion 2 decreases with increasing distance from the surface in contact with the permanent magnet powder p, the magnetic rubber portion 1a of the lid portion 1 and the magnetic rubber portion 2a of the bottom portion 2 Ratio (Sg) between the minimum horizontal cross-sectional area (Sg) and the area (Sp) of the upper surface and the lower surface of the filled permanent magnet powder p.
/ Sp) is preferably 0.1 to 0.8.

The particle size of the magnetic particles used in the magnetic rubber is
It is preferably 0.5 to 100 μm. If the particle size of the magnetic particles is less than 0.5 μm, the magnetic particles are easily oxidized and cannot be used for a long period of time. Further, when the particle diameter of the magnetic particles exceeds 100 μm, the particles are settled due to the weight of the particles themselves while being mixed with the rubber and being cured, and thus a magnetic rubber having uniform properties is prepared. Is difficult.

Silicone rubber is preferably used as the rubber used for the magnetic rubber. Silicone rubber is less likely to be deformed even if used for a long period of time, and the amount of deformation when stress is applied is also small with time, so that it can be used for a long period of time.

If either the lid or the bottom is made of normal rubber that does not exhibit magnetism, instead of magnetic rubber, the magnetic field gradient in the rubber mold can be relaxed when a magnetic field is applied. In addition, since the magnetic pole is generated in the side without the magnetic rubber and the effect of the present invention cannot be obtained, it is preferable that at least a part of both the lid and the bottom is made of the magnetic rubber. Then it is important.

Further, the thickness or height of the magnetic rubber disposed on the lid and the bottom is preferably 5 mm or more.
When the thickness of the magnetic rubber is less than 5 mm, the magnetic field gradient in the rubber mold cannot be relaxed when the pulsed magnetic field is applied, and the effect of the present invention cannot be obtained. The thickness or height of the magnetic rubber refers to the length of the magnetic rubber in the compressive stress application direction by a die press machine or the like.

The anisotropic sintered magnets to which the present invention is applied include ferrite magnets such as Ba ferrite and Sr ferrite, and rare earth magnets such as R-Co and R-Fe-B magnets. These magnets are manufactured as follows.

The ferrite magnet is made of raw materials such as iron oxide, barium oxide and strontium carbonate, and has a final composition of M.
O.6Fe ₂ O ₃ (M is Ba, Sr, etc.) is weighed and mixed so that the composition is close to, and 900 to 1200 ° C.
It is fired for about 5 hours to cause a solid phase reaction to produce a fired product such as Ba ferrite or Sr ferrite. Then
The obtained ferrite is finely pulverized to 1 μm or less, and an orientation magnetic field is applied to perform compression molding to obtain a green compact. At that time, it may be difficult to direct the easy magnetizing direction of the permanent magnet powder to the magnetic field direction due to compression. In this case, suspend the ferrite magnet powder in an appropriate liquid to form a slurry and form the magnetic field. Wet molding may be performed. Then 10
Sintering is performed at 00 to 1300 ° C. for about 1 to 5 hours to obtain a ferrite magnet.

R-Co rare earth magnets are RCo ₅ series, R
₂ Co ₁₇ series and the like. R ₂ Co ₁₇ series rare earth magnets are usually 20/28% R and 5-30% F by weight percentage.
e, 3 to 10% Cu, 1 to 5% Zr, and the balance Co, and is manufactured by the following manufacturing method. The finely pulverized R ₂ Co ₁₇ series alloy is compression molded in a magnetic field and then sintered at 1100 to 1250 ° C. for 0.5 to 5 hours,
Then, at a temperature 0 to 50 ° C. lower than the sintering temperature, 0.5 to
It is solution-treated for 5 hours and finally subjected to an aging treatment. The aging treatment is usually 700 to 900 as the first stage aging.
Hold at ℃ for a certain period of time, then perform continuous cooling or multi-step aging.

The R-Fe-B rare earth magnets usually have a weight percentage of 5 to 40% R, 50 to 90% Fe, and 0.
It consists of 2-8% B. To improve magnetic properties,
C, Al, Si, Ti, V, Cr, Mn, Co, Ni,
Cu, Zn, Ga, Zr, Nb, Mo, Ag, Sn, H
Additive elements such as f, Ta, and W are often added. In the case of Co, the addition amount of these additives is 30% by weight or less,
In the case of other elements, it is usually 8% by weight or less. If more additives are added, the magnetic properties will be deteriorated. The method for manufacturing the R-Fe-B rare earth magnet is as follows. The raw metal is weighed, melted and cast, and the obtained alloy is pulverized to an average particle size of 1 to 20 μm. Then, the crushed powder is compression molded in a magnetic field to
Sintering is performed at 000 to 1200 ° C. for 0.5 to 5 hours. Finally, aging treatment is performed at 400 to 1000 ° C, and R-Fe-B
Obtain a rare earth magnet.

(Example 1, Example 2, Comparative Example 1) Atomic%
Alloy of Nd _13.5 Dy ₁ Fe ₇₈ B _6.5 Al ₁ with a purity of 9
9.9 wt% or more of each raw material metal was melted and cast in an argon atmosphere using an induction heating high-frequency melting furnace to fabricate. This alloy ingot was heated at 1100 ° C in an argon atmosphere for 2
After performing homogenization heat treatment for 4 hours, coarsely pulverize in an argon atmosphere using a jaw crusher and a brown mill,
Then, fine pulverization was performed with a jet mill using nitrogen gas to produce R-Fe-B based permanent magnet powder having an average particle diameter of 5 μm.

This is put in the cavity of the rubber mold and R
-Fe-B based permanent magnet powder was filled to a filling density of 3 g / cc, and a pulse magnetic field of 5 T was applied, and then 0.8 ton /
The rubber mold was compressed with a pressure of cm ² . The pulse magnetic field application direction is the axial direction of the cylindrical sample, and the pressure application direction is also the same direction. The side surface of the rubber mold used here is made of only silicone rubber, not magnetic rubber. The magnetic rubber disposed on the lid and the bottom is obtained by mixing Fe ₅₀ Co ₅₀ alloy powder particles having an average particle diameter of 10 μm with silicone rubber and curing it, and has a magnetic property of saturation magnetization 4πIs of 4000 gauss. doing. The rubber mold has a cylindrical shape with an outer diameter of 60 mm, an inner diameter of 40 mm and a height of 70 mm. The magnetic rubber used in Example 1
, The diameter, as shown in FIG.
It has a cylindrical shape of 33 mm and a height of 10 mm, and in the second embodiment, as shown in FIG.
It has a truncated cone shape with an upper diameter of 33 mm, a lower diameter of 40 mm and a height of 10 mm.

The obtained green compact was sintered in vacuum at 1060 ° C. for 90 minutes, and then subjected to an aging heat treatment at 540 ° C. to produce a cylindrical R-Fe-B system sintered magnet. . The obtained cylindrical sintered magnet was cut into 5 equal parts, and the magnetic flux densities on the upper and lower surfaces of the magnet pieces were measured using a Hall element. The results were used to measure the surface magnetic flux density on the lower surface and the surface magnetic flux on the upper surface. The density ratio (lower surface / upper surface) is shown in Table 1. Also,
Table 1 shows the rate of occurrence of overhang at the corners of the green compact (ratio of the number of underpressure green compacts to the total number of tested green compacts).
I wrote it together.

Further, Table 1 shows, as Comparative Example 1, a diameter of 60 mm and a height of 1 at the lid and bottom of the rubber mold of Example 1.
The same experiment as in Example 1 was conducted using a 0 mm columnar magnetic rubber, and the side surface of the rubber mold was similarly made of silicone rubber. The results are shown. In addition, in Table 1,
"Upper", "upper middle", "center", "lower middle", "lower" mean
The position from the lid portion to the bottom portion of each of the five circular slices of the columnar sintered magnet, which is divided into five equal parts, is shown at the time of filling the cavity of the rubber mold. Therefore, "up"
Indicates the ring slice closest to the lid portion, "center" refers to the ring slice located in the middle of the five ring slices of the cylindrical sintered magnet divided into five, and "bottom" is Point to the slice that is closest to the bottom. The same applies to Tables 3 and 4 below.

[0036]

[Table 1]

According to Table 1, a rubber having a horizontal cross-sectional area partially filled in the cavity of the rubber mold and having a cross-sectional area smaller than the area of the upper and lower surfaces of the permanent magnet powder is arranged in the lid and the bottom. By using the mold, variations in the magnetic characteristics of the front and back surfaces of the magnet pieces near the lid and bottom can be more effectively suppressed. In particular, in the case of using frustoconical magnetic rubber, It can be seen that the occurrence can be effectively prevented.

(Example 3) Silicone rubber and average particle size 1
The alloy powder of Fe ₅₀ Co ₅₀ of 0 μm was mixed, and the saturation magnetization was 4
Cylindrical magnetic rubbers having πIs of 4000 gauss and different dimensions were produced, and the same outer diameter as that of Example 1 was 60.
An experiment was carried out by arranging the cylindrical rubber mold having a diameter of 40 mm, an inner diameter of 40 mm, and a height of 70 mm in a position in contact with the filled permanent magnet powder on the lid and the bottom. Of the five magnet pieces cut out from one cylindrical sintered magnet, the above-mentioned Table 1 is used.
The surface magnetic flux densities of the upper surface and the lower surface of the magnet piece in the “upper” part of were measured, and in Table 2, the surface magnetic flux density (lower surface / upper surface) was described. Further, in Table 2, the ratio of the diameter of the columnar magnetic rubber to the diameter of the columnar permanent magnetic powder filled in the cavity of the rubber mold is shown as the diameter of the magnetic rubber (magnetic rubber / filled portion diameter). ing.

[0039]

[Table 2]

From Table 2, the diameter of the magnetic rubber (magnetic rubber / filling portion diameter), that is, the ratio of the diameter of the cylindrical magnetic rubber to the diameter of the cylindrical permanent magnetic powder filled in the cavity of the rubber mold, It can be seen that in the range of 1 or less, the variation in the magnetic characteristics of the front surface and the back surface of the magnet piece near the lid is suppressed. Also, especially the diameter of the magnetic rubber (magnetic rubber / filled part diameter)
Shows that the effect is large in this range.

(Example 4, Example 5, Comparative Example 2) The alloy composition is Sm26%, Fe14%, Cu5%, Zr in% by weight.
After weighing the raw material metals so that the balance was 3% and the balance being Co, these were melted in an argon atmosphere using an induction heating high frequency melting furnace and cast to prepare an alloy ingot. This alloy ingot was coarsely crushed in an argon atmosphere using a jaw crusher and a brown mill, and then finely crushed in a jet mill using nitrogen gas to obtain an average particle size of 5 μm.
R ₂ Co ₁₇ type permanent magnet powder of was produced.

The magnetic rubber as Example 4 has a diameter of 33 as shown in FIG. 3 (a) as in Example 1.
mm and a cylindrical shape having a thickness of 10 mm, and in Example 5, a truncated cone having an upper diameter of 33 mm, a lower diameter of 40 mm and a height of 10 mm as shown in FIG. The shape. The pressure during compression molding is 1.0 ton /
cm ² and other conditions are the same as in Example 1.

The compression-molded green compact was sintered at 1200 ° C. in an argon atmosphere and solution-treated at 1180 ° C. In the aging heat treatment, first, as the first stage aging, the material was held at 850 ° C. for 2 hours, then continuously cooled to 400 ° C. at a cooling rate of 1 ° C./minute, and then rapidly cooled. The obtained R ₂ Co ₁₇ system sintered magnet was divided into 5 equal parts as in Example 1, and the surface magnetic flux densities of the upper and lower surfaces of five magnet pieces cut out from one sintered body were measured. The values of the lower surface / upper surface of The results are shown in Table 3. In addition, the rate of occurrence of overhang at the corners of the green compact is also shown.

As Comparative Example 2, a cylindrical magnetic rubber having a diameter of 60 mm and a height of 10 mm was arranged on the lid and the bottom of the rubber mold, and the side surface of the rubber mold was made of silicone rubber, and the same experiment was conducted. Are also shown in Table 3.

[0045]

[Table 3]

From Table 3, also in the R ₂ Co ₁₇ system sintered magnet, a part of the horizontal cross-sectional area of the lid and the bottom is filled in the cavity of the rubber mold, and the area of the upper and lower surfaces of the permanent magnet powder is By using a rubber mold in which a magnetic rubber having a small cross-sectional area is arranged, it is possible to more effectively suppress variations in the magnetic characteristics of the front and back surfaces of the magnet pieces near the lid and bottom, and in particular, the truncated cone shape. It can be seen that the use of the above magnetic rubber can effectively prevent the occurrence of chipping.

(Examples 6 and 7 and Comparative Example 3) Strontium carbonate (SrCO ₃ ) and ferric oxide (Fe ₂ 0)
₃ ) was mixed at a molar ratio of 1: 5.9, pulverized and mixed in a ball mill for 8 hours, and then calcinated at 1080 ° C. for 1 hour, and then pulverized using a stamp mill and a ball mill to obtain an average. Sr ferrite magnet powder having a particle size of 0.8 μm was produced. In the same manner as in Example 1, this powder was used in the form of a cylindrical column having a diameter of 33 mm and a height of 10 mm as Example 6 and a conical trapezoidal magnetic rubber having an upper diameter of 33 mm, a lower diameter of 40 mm and a height of 10 mm as Example 7. Was filled in and the rubber mold was compressed at a pressure of 0.8 ton / cm ² to perform molding.

The green compact molded as described above is
Sr ferrite sintered magnet was produced by sintering at 250 ° C.

The obtained Sr ferrite sintered magnet was divided into 5 equal parts in the same manner as in Example 1, and the surface magnetic flux densities of the upper and lower surfaces of five magnet pieces cut out from one cylindrical sintered body were measured, The values of the lower surface / upper surface are shown. The results are shown in Table 4.

As Comparative Example 3, a cylindrical magnetic rubber having a diameter of 60 mm and a height of 10 mm was arranged on the lid and the bottom of the rubber mold, and the side surface of the rubber mold was made of silicone rubber. The results are also shown in Table 4
It was noted in.

[0051]

[Table 4]

From Table 4, also in the ferrite-based sintered magnet, a part of the horizontal cross-sectional area of the lid and the bottom is smaller than the area of the upper and lower surfaces of the permanent magnet powder filled in the cavity of the rubber mold. By using the rubber mold in which the magnetic rubber having the is arranged, it is possible to more effectively suppress the variation in the magnetic characteristics of the front and back surfaces of the magnet pieces in the portions near the lid and the bottom, and in particular, the truncated cone-shaped magnetic rubber. It can be seen that in the case of using, it is possible to effectively prevent the occurrence of chipping.

[0053]

Since the present invention is constructed as described above, the following effects can be obtained.

According to the present invention, it is possible to manufacture an anisotropic sintered magnet with little variation in the residual magnetic flux density, and as a result, the manufacturing yield is improved.

[Brief description of the drawings]

FIG. 1 is a simulation diagram showing a magnetic flux distribution of a magnetized magnetic body.

FIG. 2 is a simulation diagram showing a magnetic flux distribution in a coil.

FIG. 3 is a vertical sectional view of a rubber mold as an example used in the method for producing an anisotropic sintered magnet of the present invention.

FIG. 4 is a vertical sectional view of a rubber mold as an example used in the method for producing an anisotropic sintered magnet of the present invention similar to FIG.

FIG. 5 is a vertical sectional view of a rubber mold or the like used in a conventional method for producing an anisotropic sintered magnet.

[Explanation of symbols]

 g ... Rubber mold g1 ... Cavity p ... Permanent magnet powder 1 ... Lid part 2 ... Bottom part 3 ... Side part

[Procedure amendment]

[Submission date] February 1, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction contents]

For example, as shown in FIG. 5, the entire magnetic rubber portion 1a of the lid portion 1 and the magnetic rubber portion 2a of the bottom portion 2 are covered.
Is larger than the area of the upper surface and the lower surface of the filled permanent magnet powder p, when the magnetic field is applied, the upper and lower edges g2 and g3 of the cavity g1 as the permanent magnet powder filling portion are
The lines of magnetic force that pass through are the edges of the magnetic rubber portion 1a of the lid portion 1 and the bottom portion 2.
The upper and lower edges of the cavity g1 to spread toward
Distortion of orientation in g2 and g3 cannot be suppressed
No. In addition, 4 is a pulse magnetic field generation coil for orienting the permanent magnet powder p.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0034

[Correction method] Change

[Correction contents]

The obtained green compact was sintered in vacuum at 1060 ° C. for 90 minutes, and then subjected to an aging heat treatment at 540 ° C. to produce a cylindrical R-Fe-B system sintered magnet. . The obtained cylindrical sintered magnet was cut into 5 equal parts, and the magnetic flux densities on the upper and lower surfaces of the magnet pieces were measured using a Hall element. The results were used to measure the surface magnetic flux density on the lower surface and the surface magnetic flux on the upper surface. The density ratio (lower surface / upper surface) is shown in Table 1 .

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0036

[Correction method] Change

[Correction contents]

[0036]

[Table 1]

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0043

[Correction method] Change

[Correction contents]

The compression-molded green compact was sintered at 1200 ° C. in an argon atmosphere and solution-treated at 1180 ° C. In the aging heat treatment, first, as the first stage aging, the material was held at 850 ° C. for 2 hours, then continuously cooled to 400 ° C. at a cooling rate of 1 ° C./minute, and then rapidly cooled. The obtained R ₂ Co ₁₇ system sintered magnet was divided into 5 equal parts as in Example 1, and the surface magnetic flux densities of the upper surface and the lower surface of the five magnet pieces cut out from one sintered body were measured. The values of the lower surface / upper surface of The results are shown in Table 3.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0045

[Correction method] Change

[Correction contents]

[0045]

[Table 3]

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0051

[Correction method] Change

[Correction contents]

[0051]

[Table 4]

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0052

[Correction method] Change

[Correction contents]

From Table 4, also in the ferrite-based sintered magnet, a part of the horizontal cross-sectional area of the lid and the bottom is smaller than the area of the upper and lower surfaces of the permanent magnet powder filled in the cavity of the rubber mold. the use of rubber molds arranged magnetic rubber with the variation of the magnetic characteristics of the surface and the back surface of the magnet piece in the portion near the lid and the bottom, it can be seen that more effectively suppressed et al.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Takehisa Minowa 2-5, Kitafu, Takefu City, Fukui Prefecture Shinetsu Kagaku Kogyo Co., Ltd. Magnetic Materials Research Institute (72) Masato Sagawa Inoue Matsumuro, Nishikyo-ku, Kyoto City, Kyoto Prefecture 1 Ellie Part 2 at No. 22 Uemachi No. 401 in Inter Metalix Co., Ltd. (72) Inventor Hiroshi Nagata No. 1 Elly Part No. 2 at No. 22 in Inter Metalix Co., Ltd. 22 Matsumatsu Ouegamicho, Nishikyo-ku, Kyoto City, Kyoto Prefecture (72) Inventor Toshihiro Watanabe 1 Elie Part 2 No. 401, Intermetalix Co., Ltd. 22-22 Matsumuro Ouekamicho, Nishikyo-ku, Kyoto-shi, Kyoto Prefecture

Claims (3)

[Claims] 1. A magnetic rubber portion which is a composite of rubber and magnetic particles, and at least a portion of a portion in contact with the upper and lower surfaces of the permanent magnet powder filled in the cavity of the lid portion and the bottom portion is formed, A permanent magnet powder is filled into a cavity of a rubber mold whose side surface portion is formed of rubber having no magnetism, and then a magnetic field is applied to the rubber mold filled with the permanent magnet powder and the rubber mold is compressed. A method for manufacturing an anisotropic sintered magnet, comprising molding a green compact of permanent magnet powder by, and then sintering the green compact, comprising at least a horizontal cross-sectional area of the magnetic rubber portion of the lid portion and the bottom portion. A method for producing an anisotropic sintered magnet, characterized in that a part thereof is filled in the cavity of the rubber mold and is smaller than the area of the upper and lower surfaces of the permanent magnet powder. 2. An area of a portion of the magnetic rubber portion of the lid portion and a portion of the magnetic rubber portion of the bottom portion, which are in contact with the permanent magnet powder, is smaller than the areas of the upper and lower surfaces of the permanent magnet powder. 1. The method for producing an anisotropic sintered magnet according to 1. 3. The areas of the portions of the magnetic rubber portion of the lid portion and the bottom portion which are in contact with the permanent magnet powder filled in the cavities are both equal to or larger than the areas of the upper and lower surfaces of the permanent magnet powder, and The method for producing an anisotropic sintered magnet according to claim 1, wherein at least a part of the horizontal cross-sectional area of the magnetic rubber portion is smaller than the area of the upper and lower surfaces of the permanent magnet powder.