JPH07173505A - Production of rare earth-transition metal permanent magnet and press-forming machine therefor - Google Patents

Abstract

PURPOSE:To easily and uniformly supply a fine powder to a die and a forming space when a magnet flattened in the magnetization direction is produced and improve the magnetic characteristics. CONSTITUTION:An upper punch 3 is sufficiently raised, and a specified powder is supplied to a forming space formed by left and right compaction dies 1 and 2 and a lower punch 4. The feed part of the fine powder is wide enough as compared with the conventional right-angle magnetic field forming method, and hence the powder is uniformly supplied. When the upper punch 3 is lowered to a specified position after the powder was supplied, a magnetic field is impressed by a magnetic field generating coil 5, and the powder is compacted by the punches 1 and 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding a rare earth-transition metal permanent magnet capable of easily and uniformly feeding fine powder into a molding space between a die and a lower punch and improving magnetic characteristics. Is.

[0002]

2. Description of the Related Art In recent years, along with the market trend toward miniaturization and weight reduction of electronic devices and precision instruments, rare earth-transition metal permanent magnets having a high energy product have been replaced with conventional alnico magnets and ferrite magnets in permanent magnets. It has come to be used in many fields. Since this rare earth-transition metal permanent magnet can obtain a high energy product, the magnet shape is flat in the magnetization direction from a large one made of a conventional alnico magnet or ferrite magnet, and small articles are mainly used. is occupying. Further, there is a strong demand for higher performance, and rare earth-transition metal-based permanent magnets using powder metallurgy are the mainstream of permanent magnets with high energy products that are currently put to practical use in the market. .

By the way, in the method for producing the rare earth-transition metal sintered magnet by the powder metallurgy method, the rare earth-transition metal alloy is melted in the intended composition, and the average particle diameter of the rare earth-transition metal alloy is 1 to 1.
After finely pulverizing to a powder of about 50 μm, molding in a magnetic field,
A method that goes through the steps of sintering and heat treatment is generally used. In the molding step, a finely pulverized powder having an average particle diameter of 1 to 50 μm is filled in a molding space formed by a die and a lower punch, and then an orientation magnetic field is applied to the raw material powder until the upper punch descends and finishes the consolidation of the raw material powder. Alignment is performed by continuing to apply, and depending on the direction in which the orientation magnetic field is applied, (a)
A right-angle magnetic field molding method in which the consolidation direction F and the orientation magnetic field direction M are perpendicular to each other (see FIG. 4), (b) a parallel magnetic field molding method in which the consolidation direction F and the orientation magnetic field direction M are parallel (see FIG. 5), It is divided into two.

[0004]

By the way, in the case of producing a magnet flat in the magnetizing direction, the method for forming in a perpendicular magnetic field in (a) can produce an I-H curve having good squareness and high magnetic properties. Since the compaction direction and the orientation magnetic field direction are perpendicular to each other, the molding space formed by the die and the lower punch is long in the vertical direction, and the supply port for feeding fine powder having an average particle diameter of about 1 to 50 μm to the molding space is narrow. . Therefore, there is a problem that it is difficult to feed the fine powder to the molding space, and it is impossible to manufacture a uniform molded body with little variation. On the other hand, in the parallel magnetic field molding method of (b), there is no problem of supplying fine powder to the molding space, but since the compaction direction and the orientation magnetic field direction are parallel, the orientation of the fine powder is disturbed during compaction (a ) Compared to I)
There is a problem that the squareness of the H curve is bad and the magnetic characteristics are deteriorated.

Therefore, according to the present invention, when manufacturing a magnet flat in the magnetizing direction, it is possible to easily and uniformly feed a fine powder into a molding space, and a flat rare earth having a high IH curve squareness. It is an object to provide a method capable of manufacturing a transition metal-based permanent magnet. Moreover, this invention also makes it a subject to provide the press molding machine which can manufacture such a magnet.

[0006]

As described above, in order to obtain a flat magnet having high magnetic characteristics, the orientation magnetic field direction and the consolidation direction must be orthogonal to each other. However, since the consolidation direction of the conventional press molding machine is the vertical direction as shown in FIG. 4, there is a problem in supplying fine powder. However, the present inventor has found that if the consolidation direction is not the vertical direction but the horizontal direction, the fine powder supply port can be widened while making the orientation magnetic field direction and the consolidation direction orthogonal to each other. The present invention has been made based on this finding, press molding rare earth-transition metal-based permanent magnet raw material powder in the orientation magnetic field,
In the method for producing a rare earth-transition metal permanent magnet for sintering the compact, a direction in which the consolidation direction forms an angle with the vertical direction of (90 ° -powder repose angle) or more and (90 ° + powder repose angle) or less. In addition, the method for producing a rare earth-transition metal-based permanent magnet is characterized in that the orienting magnetic field is applied in the vertical direction.

The present invention will be described below with reference to the drawings. Figure 1
FIG. 3 is a conceptual diagram showing a molded body manufacturing process of the manufacturing method of the present invention. In FIG. 1, reference numerals 1 and 2 denote a left consolidation die and a right consolidation die, respectively, which are reciprocated horizontally by a drive source (not shown) so that the consolidation direction is horizontal. Reference numerals 3 and 4 are an upper punch and a lower punch, respectively, which are reciprocally moved in the vertical direction by a driving source (not shown). Reference numeral 5 denotes a magnetic field generating coil, which applies a magnetic field in the direction of arrow M.

In order to form a compact, the upper punch 3 is first sufficiently raised, and a predetermined fine powder is supplied to the compact space formed by the left and right consolidation dies 1 and 2 and the lower punch 4 (see FIG. 1 (a)). Since the fine powder supply port is wider than in the conventional rectangular magnetic field molding method, uniform supply can be performed.
After the fine powder supply is completed, the upper punch 3 is lowered to a predetermined position (see FIG. 1B), a magnetic field is applied by the magnetic field generating coil, and the left and right consolidation punches 3 and 4 are consolidated and molded (FIG. 1). (See (c) and (d)). At this time, since the compaction direction and the magnetic field application direction are orthogonal to each other, the orientation is not disturbed by the compaction. Orientation is performed by continuing to apply an orientation magnetic field until compaction is completed, and a molded body is produced. When the fine powder is oriented, it is possible to use a pulse magnetic field together to improve the degree of orientation. The compacting space formed by the die and the lower punch has a ratio of the square of the thickness in the magnetizing direction to the area of the plane perpendicular to the magnetizing direction when the compact is compacted, and the thickness in the magnetizing direction is the magnetizing direction. Set to be smaller than the length of the short side of the plane perpendicular to.

Next, this molded body is placed in a vacuum or nitrogen,
1000 to 1300 ° C in a non-oxidizing atmosphere such as Ar gas
And sintered at a temperature in the range of 350 ° C. to the sintering temperature to produce a permanent magnet. The magnet alloy which is the object of the present invention is a rare earth-transition metal alloy Sm—Co magnet and R—Fe—B magnet (one or a combination of two or more rare earth elements including R: Y). . The average particle size of these alloys is 1 to 50 μm using a crusher or the like.
It is made into a fine powder to a degree and used in the production method of the present invention. In the manufacturing method of the present invention, the consolidation direction is not limited to the horizontal direction shown in FIG. 1, but also the vertical direction and (90 ° −repose angle of fine powder) or more (9
Angles up to 0 ° + angle of repose of fine powder) are allowed. If this angle is deviated, even if the fine powder is uniformly fed to the forming space formed by the die and the lower punch of the molding machine, the fine powder will slip due to vibration of the molding or its own weight, etc., and the uniformity of the fine powder in the forming space will be improved. become worse. As a result, a non-uniform molded body is formed, and the magnetic properties are deteriorated.

Next, if the ratio of the square of the thickness in the magnetization direction to the area of the plane perpendicular to the magnetization direction is 1 or less and the thickness in the magnetization direction is smaller than the length of the short side of the plane perpendicular to the magnetization direction. But
If the ratio of the square of the thickness in the magnetization direction to the area of the plane perpendicular to the magnetization direction is 1 or more, or if the thickness in the magnetization direction is larger than the length of the short side of the plane perpendicular to the magnetization direction, the die of the molding machine and the bottom The average particle size is 1 to 50 in the molding space formed by the punch.
This is because it is not possible to uniformly feed the fine powder having a size of about μm and the variation of the molded body becomes large, which is not preferable in manufacturing.

[0011]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

(Example 1) Nd 30.0 wt. %, Dy
2.0 wt. %, Al 0.3 wt. %, Nb 1.0w
t. %, B 1.0 wt. % The magnet alloy consisting of the balance Fe is pulverized into fine powder having an average particle diameter of 4.2 μm. This fine powder having an average particle diameter of 4.2 μm is formed by the compacting dies 1 and 2 and the lower punch 4 of the molding machine shown in FIG. 1 which has a compaction direction horizontal and has a device for generating a magnetic field in the vertical direction. After filling the molding space (cross-sectional area: 20 × 20 mm), the upper punch 3 was lowered, and an orientation magnetic field of about 10 kOe was applied for orientation. After that, the raw material powder is horizontally
Compacted by ton / cm ² (20x10x5m
m, magnetization direction: thickness 5 mm direction) was obtained. Next, this compact was sintered under the conditions of 1080 ° C. for 2 hours, and 600 ° C.
Heat treatment was performed for 2 hours to produce a permanent magnet. The magnetic properties of this permanent magnet and the difficulty of supplying fine powder to the molding space are shown in Table 1, and the I-H curve is shown in FIG.

(Example 2) Nd 30.0 wt. %, Dy
2.0 wt. %, Al 0.3 wt. %, Nb 1.0w
t. %, B 1.0 wt. % The magnet alloy consisting of the balance Fe is pulverized into fine powder having an average particle diameter of 4.2 μm. The fine powder having an average particle diameter of 4.2 μm is compacted in a compaction die of a compactor having a device for generating a magnetic field in the vertical direction and a compacting die (lower cross-sectional area: 13 × 20 mm) formed by a compacting machine having a vertical magnetic field generating device. After filling, the upper punch was lowered, and an orienting magnetic field of about 10 kOe was applied for orienting. Then, the raw material powder was horizontally compacted at ² ton / cm ² to obtain a compact (13 × 13 × 12 mm, magnetization direction: thickness 12).
mm direction) was obtained. Next, the molded body was sintered under the condition of 1080 ° C. for 2 hours and heat-treated at 600 ° C. for 2 hours to produce a permanent magnet. Table 1 shows the magnetic characteristics of this permanent magnet and the difficulty of supplying fine powder to the molding space.

(Example 3) Nd 30.0 wt. %, Dy
2.0 wt. %, Al 0.3 wt. %, Nb 1.0w
t. %, B 1.0 wt. % The magnetic alloy consisting of the balance Fe is pulverized into fine powder having an average particle diameter of 4.2 μm (repose angle = 50 °). The compaction direction of this fine powder having an average particle diameter of 4.2 μm is the direction forming an angle of 70 ° with the vertical direction,
A molding space formed by a die and a lower punch of a molding machine having a device for generating a magnetic field in the vertical direction (cross-sectional area: 20x
20 mm, having an inclination angle of 70 ° with respect to the magnetization direction), and then the upper punch was lowered, and an orientation magnetic field of about 10 kOe was applied for orientation. Then, the raw material powder was compacted in a direction forming an angle of 70 ° with the vertical direction at ² ton / cm ² to obtain a compact (20 × 10 × 5 mm, cross-sectional area having an inclination angle of 70 ° with respect to the magnetization direction, the magnetization direction: 5mm thickness
Direction) got. Next, the molded body was sintered under the condition of 1080 ° C. for 2 hours and heat-treated at 600 ° C. for 2 hours to produce a permanent magnet. Table 1 shows the magnetic characteristics of this permanent magnet and the difficulty of supplying the fine powder to the molding space.

(Comparative Example 1) Nd 30.0 wt. %, Dy
2.0 wt. %, Al 0.3 wt. %, Nb 1.0w
t. %, B 1.0 wt. % The magnet alloy consisting of the balance Fe is pulverized into fine powder having an average particle diameter of 4.2 μm. A compacting space (cross-sectional area: 2
(0x10 mm) and then lower the upper punch to about 1
Orientation was performed by applying an orientation magnetic field of 0 kOe. Then, the raw material powder was vertically compacted at ² ton / cm ² to obtain a compact (20 × 10 × 5 mm). Next, 1
Sintering was performed under conditions of 080 ° C. for 2 hours, and heat treatment was performed at 600 ° C. for 2 hours to produce a permanent magnet. Table 1 shows the magnetic characteristics of this permanent magnet and the difficulty of supplying fine powder to the molding space.
The -H curve is shown in FIG.

(Comparative Example 2) Nd 30.0 wt. %, Dy
2.0 wt. %, Al 0.3 wt. %, Nb 1.0w
t. %, B 1.0 wt. % The magnet alloy consisting of the balance Fe is pulverized into fine powder having an average particle diameter of 4.2 μm. A compacting space (cross-sectional area: the fine powder having an average particle diameter of 4.2 μm) is formed by a die and a lower punch of a molding machine having a device for generating a magnetic field in a direction perpendicular to the consolidation direction and a direction perpendicular to the consolidation direction. (20 × 5 mm), the upper punch was lowered, and an orienting magnetic field of about 10 kOe was applied for orienting. Then, the raw material powder was vertically compacted at ² ton / cm ² to obtain a compact (20 × 10 × 5 mm, magnetization direction: thickness 5 mm direction). Next, the molded body is 1080
Sintering was performed under the conditions of 2 ° C. and 2 hours, and heat treatment was performed at 600 ° C. for 2 hours to produce a permanent magnet. The magnetic properties of this permanent magnet and the difficulty of supplying fine powder to the die are shown in Table 1, and the I-H curve is shown in FIG.

(Comparative Example 3) Nd 30.0 wt. %, Dy
2.0 wt. %, Al 0.3 wt. %, Nb 1.0w
t. %, B 1.0 wt. % The magnetic alloy consisting of the balance Fe is pulverized into fine powder having an average particle diameter of 4.2 μm (repose angle = 50 °). A molding space for forming the fine powder having an average particle diameter of 4.2 μm by a die and a lower punch of a molding machine having a device for generating a magnetic field in the vertical direction in a direction in which the compaction direction forms an angle of 35 ° with the vertical direction ( Cross-sectional area: 20x20
mm, having a tilt angle of 35 ° with respect to the magnetization direction), the upper punch was lowered, and then an orientation magnetic field of about 10 kOe was applied to orient the powder. Then, the raw material powder was compacted in a direction forming an angle of 35 ° with the vertical direction at ² ton / cm ² to obtain a compact (20 × 10 × 5 mm, cross-sectional area having an inclination angle of 35 ° with respect to the magnetization direction, magnetization direction: The thickness was 5 mm). Next, the molded body is heated to 1080 ° C., 2
Sintering was performed under the condition of time, and heat treatment was performed at 600 ° C. for 2 hours to produce a permanent magnet. Table 1 shows the magnetic characteristics of this permanent magnet and the difficulty of transferring the fine powder to the die.

(Comparative Example 4) Nd 30.0 wt. %, Dy
2.0 wt. %, Al 0.3 wt. %, Nb 1.0w
t. %, B 1.0 wt. % The magnet alloy consisting of the balance Fe is pulverized into fine powder having an average particle diameter of 4.2 μm. A molding space (cross-sectional area: 2) for forming the fine powder having an average particle diameter of 4.2 μm by a die and a lower punch of a molding machine having a device for generating a magnetic field in the vertical direction with a horizontal compaction direction.
(0x20 mm), the upper punch was lowered, and then an orienting magnetic field of about 10 kOe was applied to orient the powder.
Then, the raw material powder was horizontally consolidated at ² ton / cm ² to form a compact (20 × 10 × 15 mm, magnetization direction: thickness 1).
5 mm direction) was obtained. Next, the molded body was sintered under the condition of 1080 ° C. for 2 hours and heat-treated at 600 ° C. for 2 hours to produce a permanent magnet. Table 1 shows the magnetic properties of this permanent magnet and the difficulty of supplying fine powder to the die.

[0019]

[Table 1]

[0020]

According to the present invention, when a magnet flat in the magnetizing direction is manufactured, it is possible to easily and uniformly feed fine powder to the die and the molding space, and to improve the magnetic characteristics. The utility value is extremely high.

[Brief description of drawings]

FIG. 1 is a diagram showing a powder molding step of the production method of the present invention.

FIG. 2 is a diagram showing a consolidation direction of the manufacturing method of the present invention.

FIG. 3 is an I-H curve of an example and a comparative example.

FIG. 4 is a diagram showing a conventional method for forming in a perpendicular magnetic field.

FIG. 5 is a diagram showing a conventional parallel magnetic field molding method.

[Explanation of symbols]

1 left consolidation die, 2 right consolidation die, 3 upper punch,
4 lower punch, 5 magnetic field generator, 6 dice

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01F 41/02 G

Claims (7)

[Claims] 1. A method for manufacturing a rare earth-transition metal permanent magnet, comprising press-molding a rare earth-transition metal permanent magnet raw material powder in an orienting magnetic field and sintering the compact, wherein the consolidation direction is the vertical direction (90). ° -powder angle of repose) or more (90 ° +
The angle of repose of the powder) is less than or equal to
A method for manufacturing a rare earth-transition metal permanent magnet, characterized in that an orienting magnetic field is applied in the vertical direction. 2. A method for manufacturing a rare earth-transition metal permanent magnet, comprising press-molding a rare earth-transition metal permanent magnet raw material powder in an orienting magnetic field and sintering the compact, wherein the consolidation direction is the vertical direction and the vertical direction. And (90 ° -powder repose angle)
A method for producing a rare earth-transition metal-based permanent magnet, characterized in that the orientation magnetic field is applied in a vertical direction while having a direction of an angle not less than (90 ° + powder repose angle). 3. The rare earth-transition metal according to claim 1, wherein a direction which forms an angle of not less than (90 ° −powder repose angle) and not more than (90 ° + powder repose angle) with the vertical direction is a horizontal direction. Method for manufacturing a permanent magnet. 4. The molded body has a thickness of 2 in the magnetic field application direction.
The ratio of the square to the area of a surface perpendicular to the magnetic field application direction is 1 or less, and the thickness of the magnetic field application is smaller than the length of a short side of the surface perpendicular to the magnetic field application direction. Manufacturing method of rare earth-transition metal permanent magnet. 5. A compaction means that operates in a direction that forms an angle of (90 ° −powder repose angle) or more and (90 ° + powder repose angle) or less with the vertical direction, and a magnetic field generation means that applies a magnetic field in the vertical direction. And a press forming apparatus. 6. A compaction means that operates in a vertical direction and a direction that forms an angle of (90 ° −powder repose angle) or more and (90 ° + powder repose angle) or less with the vertical direction, and applies a magnetic field in the vertical direction. A press forming apparatus comprising: a magnetic field generating means. 7. The press molding apparatus according to claim 5, wherein a direction which forms an angle of not less than (90 ° −powder repose angle) and not more than (90 ° + powder repose angle) with the vertical direction is a horizontal direction.