JPH0774042A - Manufacture of rare-earth magnet and molding apparatus used for it - Google Patents

Abstract

PURPOSE:To easily handle a molded body, to prevent the molded body from being oxidized and to reduce the contend of oxygen in a magnet by a method wherein the molded body obtained by a molding process is immersed in a hydrophobic organic-substance liquid. CONSTITUTION:A molded body 19 obtained by molding a raw material between an upper metal mold 14 and a lower metal mold 15 is conveyed onto a carrying- out belt 20 via a chute 18, it is housed further inside a hydrophobic organic- substance liquid container 5 via a chute 23, and it is transferred into a conveyance belt 24 which is arranged in a hydrophobic organic-substance liquid 5a. Then, in a process in which the molded body is transferred onto the conveyance belt 24, it is passed through the hydrophobic organic-substance liquid 5a, its surface is wetted with the hydrophobic organic-substance liquid 5a, and it is set to a state that it does not come into direct contact with the air. Thereby, the molded body can be handled easily its oxidation can be prevented, and the content of oxygen in a rare-earth permanent magnet can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a molding apparatus for molding raw material powder of rare earth permanent magnets such as Nd-Fe-B system permanent magnets, a method for manufacturing rare earth magnets using the molding apparatus, and an apparatus therefor.

[0002]

2. Description of the Related Art In recent years, Sm which has higher magnetic characteristics and is more expensive in terms of resources than conventional Sm-Co magnets.
Practical application of Nd-Fe-B based permanent magnets containing no or Co is under way. It is known that the magnetic characteristics of the Nd-Fe-B system permanent magnet are strongly influenced by the oxygen content, and the magnetic characteristics become better as the oxygen content is suppressed to a lower level.

Therefore, research has been conventionally conducted on the Nd-Fe-B system permanent magnets for suppressing the oxygen content thereof to a low level. As a result of the research, a method for molding a permanent magnet alloy powder in which the raw material powder is molded in an inert atmosphere has been proposed (Japanese Patent Laid-Open No. 61-287107). This method of molding the permanent magnet alloy powder is effective as a method of reducing the oxygen content of the Nd-Fe-B system permanent magnet.

[0004]

However, the above-mentioned conventional N
The method for reducing the oxygen content of the d-Fe-B based permanent magnet has the problems described below. Rare earths such as Nd are very easily oxidized and react with oxygen in the atmosphere to ignite. Therefore, a material having a reduced oxygen content always has a risk of fire or the like when it is handled, and specifically, the material itself is burned when it comes into contact with the atmosphere, which causes a problem that the material is difficult to handle. Further, even if the molding is carried out in an inert atmosphere, it is difficult to completely shield the molded body from the atmosphere until the sintering step thereafter, so that the oxygen content of the Nd-Fe-B permanent magnet is further lowered. For that reason, it was still incomplete, and there was room for further improvement in that respect.

Therefore, the present invention has been made in view of the above problems of the prior art, and in the manufacturing process of rare earth permanent magnets such as Nd-Fe-B system permanent magnets, handling of the molded product obtained by the molding process. It is an object of the present invention to provide a method for manufacturing a rare earth magnet and a molding apparatus used for the method, which facilitates the oxidation, prevents oxidation of the molded body, and thoroughly reduces the oxygen content of the magnet.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted various studies to achieve the above-mentioned objects of the present invention, and when the molded product is dipped in a hydrophobic organic liquid, the surface of the molded product is a hydrophobic organic liquid. Since it is wetted by and is shielded from the atmosphere, the rare earth in the molded body can be prevented from being oxidized, and the handling is easy, and Nd-Fe-
The inventors have come up with the idea that the oxygen content of rare earth magnets such as B-based permanent magnets can be reduced, and have achieved the above object.

That is, the manufacturing method of the present invention is a method for manufacturing a rare earth magnet having a molding step, in which the molded body obtained by the molding step is immersed in a hydrophobic organic liquid. Further, a rare earth magnet having a lower oxygen content can be obtained by immersing the molded product molded in the inert atmosphere in the hydrophobic organic liquid.

Further, a manufacturing method for obtaining a rare earth magnet having a low oxygen content was found. That is, a hydrogen pulverization treatment step, a coarse pulverization treatment step, a fine pulverization treatment step,
In a method for manufacturing a rare earth magnet having a molding step and a sintering step, the coarse pulverization processing step, the fine pulverization processing step, and the molding step are performed under an inert atmosphere, and each of the above-mentioned steps before the sintering step is performed. In the method for producing a rare earth magnet, the steps between the steps are carried out in an inert atmosphere, and the molded body obtained in the molding step is immersed in a hydrophobic organic liquid and then subjected to the sintering step. The hydrophobic organic liquid is, for example, an organic solvent such as normal hexane, toluene or fluorocarbon, or mineral oil. Since the hydrophobic organic liquid is volatilized by heating during sintering, it does not remain as an impurity in the magnet to the extent that it adversely affects the magnetic properties.

Further, the inventors of the present invention have found out a molding apparatus that realizes the method for manufacturing the rare earth magnet. It is a raw material powder molding device comprising a molding machine having an upper mold and a lower mold and a hydrophobic organic liquid container into which a molded body is dipped. Molding part of molding machine (upper mold and lower mold and space between them: Fig. 1 molding part 2
9) is maintained in an inert atmosphere, a rare earth magnet having a lower oxygen content can be obtained.

Further, the manufacturing apparatus of the present invention further comprises hydrogen crushing means, coarse crushing means continuous with the hydrogen crushing means, fine crushing means continuous with the coarse crushing means, and fine crushing means. In a device for producing a rare earth magnet, which comprises a forming means continuous to the forming means, and a sintering means continuous to the forming means, the coarse pulverizing means, the fine pulverizing means, and the forming means are in an inert atmosphere. Along with being arranged below, the hydrogen pulverization processing means, the coarse pulverization processing means,
A handling means under an inert atmosphere is provided between the fine pulverization processing means and the molding means, and the molded body molded by the molding machine is conveyed into the hydrophobic organic liquid in the hydrophobic organic liquid container in a state where the outside air is blocked. It is characterized in that the molding means is constituted by a molding device provided with a conveying means for carrying out.

In the present invention, the inert atmosphere means
An atmosphere formed by a gas having low reactivity such as N ₂ , CO ₂ , Ar, and He. The oxygen concentration in the inert atmosphere is preferably 20 ppm to 6000 ppm. 6000
When the content exceeds ppm, the molded body contains excessive oxygen during the molding process, and the quality of the obtained rare earth permanent magnet becomes unsatisfactory. On the other hand, oxygen concentration is 20ppm
It is extremely difficult industrially to make the amount less than the above value, and even if such oxygen concentration can be realized, the actual profit commensurate with the cost required therefor cannot be obtained.

It is preferable that the powder is handled during each step from the coarse crushing process to the molding by carrying an inert gas. In the present application, the term “inert gas transportation” means N ₂ , CO ₂ , Ar, and He.
It means that the powder is conveyed by a gas flow of a gas having low reactivity such as.

[0013]

According to the present invention, the molded body immersed in the hydrophobic organic liquid can be prevented from being oxidized because the surface of the molded body is wetted by the hydrophobic organic liquid and does not come into direct contact with the atmosphere. Is safe and easy to handle. Since the hydrophobic organic substance liquid is a hydrophobic organic substance such as normal hexane or mineral oil, a dehumidifying effect can be obtained. Further, by immersing the formed body formed in the inert atmosphere in the hydrophobic organic liquid, a rare earth magnet having lower oxygen can be obtained.

Further, according to the method and apparatus for manufacturing a rare earth magnet of the present invention, the steps from the hydrogen crushing step to the step before sintering are consistently performed in an inert atmosphere, and the raw material powder is completely airtight. The ultra-low oxygen molded product obtained can be carried out under the conditions, and the obtained ultra-low oxygen molded product is transported to the hydrophobic organic liquid in the hydrophobic organic liquid container connected in the external air blocking condition in the external air blocking condition and its surface is hydrophobic. Since it is transported to the sintering means in a state where it is wet with the volatile organic liquid and does not come into direct contact with the atmosphere, it is possible to safely and easily perform the sintering process even if extremely low oxygen compacts that are dangerous to handle are handled in the atmosphere. ,
The atmosphere contact of the work is completely prevented until the sintering / cooling is completed after the hydrogen pulverization treatment, and the rare earth permanent magnet having an extremely low oxygen content and good magnetic properties can be obtained under safe operating conditions.

[0015]

EXAMPLES A method for manufacturing a rare earth magnet and a molding apparatus for raw material powder, which are examples of the present invention, will be described below. 1 and 2 are conceptual views of a raw material powder molding apparatus of the present invention, and FIG. 3 is a partial perspective view showing a molding machine portion of the raw material powder molding apparatus of the present invention.

As shown in the figure, the molding apparatus 1 includes a raw material tank 2 in which the raw material powder obtained in the crushing / mixing step, which is a pre-process, is stored, and a sintering furnace 3, which is a post-process, for sintering. The molding portion 29 of the molding machine 13 provided on the base 1b and interposed therebetween is airtightly held by the airtight box 1a. The inside of the airtight box 1a of the molding apparatus 1 is set to an Ar atmosphere and is maintained at a little higher than atmospheric pressure, and is connected to the raw material tank 2 by an airtight valve 4. Although the raw material powder is stored in the raw material tank 2, it can be directly mounted on the airtight valve 4 and used, and the raw material powder is not exposed to the atmosphere. On the other hand, a hydrophobic organic substance liquid container 5 is arranged between the airtight box 1a and the sintering furnace 3, and the hydrophobic organic substance liquid container 5a is accommodated in the hydrophobic organic substance liquid container 5.
It should be noted that the sintering furnace 3 is provided with an atmosphere / vacuum replacement chamber 6, and the atmosphere / vacuum replacement chamber 6 is provided with a closed door 7 on the atmosphere side and is provided between the sintering furnace 3 and the atmosphere. A closed door 8 is provided.

A raw material receiving hopper 9 is provided below the airtight valve 4 on the raw material tank 2 side in the airtight box 1a.
The raw material receiving hopper 9 receives the raw material flowing down from the raw material tank 2 via the airtight valve 4. A weighing device 10 is attached to the raw material receiving hopper 9, and a powder feeding device 11 is provided near the weighing device 10 on the discharge port side of the weighing device 10. The powder feeding device 11 is arranged on the powder feeding table 12, and the powder feeding table 12 is arranged so as to extend between the upper and lower molds 14 and 15 of the molding machine 13. Further, the powder feeding device 11 is provided with a transfer cylinder 16, and the powder feeding device 11 can be moved back and forth by the transfer cylinder 16 so that the powder feeding table 1
It is reciprocated from the position between the upper and lower molds 14 and 15 to the position below the weighing device 10 on the upper part of the upper part 2.

As shown in FIG. 3, the molding machine 13 is mounted on a base body 1b, and the base body 1b is attached to the airtight box 1a through an airtight flange 17, and as a result, the airtight box 1a and the base body 1b. And are in series inside and connected to the outside in a gastight manner.

That is, the airtight flange 17 is formed integrally with the airtight box 1a, and the airtight flange 17 is provided with a large number of stop holes 171. On the other hand, the base 1b
Is formed in a box shape having a communication hole portion 1b1 in the front and back, and the airtight flange 17 of the airtight box 1a is brought into contact with the front and rear side surface portions 1b2 of the airtight box 1a, and a screw is screwed into the stop hole 171 to form the airtight box 1a. The base 1b is connected to the outside in an airtight state via the airtight flange 17.

Upper and lower molds 1 of the molding machine 13 of the powder feeding table 12
The end extending between 4 and 15 is connected to one end of the chute 18, and the other end of the chute 18 is continuous with the carry-out zone 20 of the molded body 19 and is located below the end of the carry-out zone 20 on the chute 18 side. A powder removing device 21 is arranged. The dedusting device 21 is composed of an electromagnet that is arranged below the compact 19 on the unloading body 20 and generates an alternating magnetic field, so that the compact on the unloading band 20 is dedusted.

As shown in FIGS. 1 and 2, one end of the hydrophobic organic liquid container 5 is at the airtight box 1a, and the end 22 of the airtight box 1a is inside the hydrophobic organic liquid 5a inside the hydrophobic organic liquid container 5. It is soaked and arranged so that the airtightness in the airtight box 1a is maintained by the hydrophobic organic liquid 5a. The other end of the hydrophobic organic liquid container 5 contacts the atmosphere. Airtight box 1 from inside the hydrophobic organic liquid container 5
A chute 23 is provided as a means for transporting the molded body 19 to a, one end of the chute 23 is continuous with the carry-out zone 20 arranged in the airtight box 1a, and the other end of the chute 23 is hydrophobic. It continues to the transport belt 24 arranged in the hydrophobic organic liquid container 5 housed in the organic liquid container 5. Further, the chute 23 is arranged between the airtight box 1a and the hydrophobic organic liquid container 5.

Therefore, since the inside of the hydrophobic organic liquid container 5 and the inside of the airtight box 1a communicate with each other in an airtight manner, the inner atmosphere of the airtight box 1a and the hydrophobic property of the hydrophobic organic liquid container 5 on the airtight box 5a side. Organic liquid 5a
The atmosphere of the space portion 5b above is adjusted to the same state.

Further, the carrier band 24 arranged in the hydrophobic organic liquid 5a in the hydrophobic organic liquid container 5 is continuous with another carrier band 25, and one end of the carrier band 25 is connected to the carrier band 24. It is continuous and the other end is continuous with the carrier zone 26 arranged outside the hydrophobic organic liquid container 5. In parallel with this, a sintering dish 27 is prepared in the carrying zone 26, and the molded body 19 can be transferred from the carrying zone 26 to the sintering dish 27 by an appropriate means (not shown). In addition, the carrier 26
1 is continuous with the carrier 25, but the atmosphere / vacuum displacement chamber 6 of the sintering furnace 3 is arranged in the vicinity of the other end, and the molded body 19 arranged on the sintering plate 27 is exposed to the atmosphere. It is carried into the sintering furnace 3 through the vacuum displacement chamber 6.

Therefore, according to the raw material powder molding apparatus of the above-described embodiment, the raw material powder is molded and carried out to the sintering furnace as follows. The inside of the airtight box 1a is set to an Ar gas atmosphere in advance, and the oxygen concentration is adjusted to be 20 ppm to 6000 ppm. In this state, the raw material is first supplied from the raw material tank 2 to the raw material receiving hopper 9 through the airtight valve 4. The raw material is stored in the raw material receiving hopper 9 and is weighed by the weighing device 10 so that a predetermined amount of the raw material is supplied to the powder feeding table 12
The powder is supplied to the powder feeding device 11 arranged above. The powder feeding device 11 to which the raw material is supplied is transferred to the molding machine 1 by the transfer cylinder 16.
3 is conveyed between the upper and lower molds 14 and 15 and set at a predetermined molding position, and the upper and lower molds 14 and 15 are operated in a state where the powder feeding device 11 is set at a predetermined position to obtain a molded body 19. . The obtained molded body 19 is conveyed to the chute 18.

The compact 19 obtained by molding the raw material between the upper and lower molds 14 and 15 is conveyed onto the unloading zone 20 via the chute 18 and is carried out by the powder removing device 21.
Powder is removed in the process of being conveyed above. The molded body 19 is transferred from the carry-out zone 20 onto the chute 23 via the airtight connection portion 22 to the transport zone 24 arranged in the hydrophobic organic matter liquid 5a contained in the hydrophobic organic matter liquid container 5. In this case, the oxygen concentration in the airtight box 1a is 20 ppm
Since it is set to ˜6000 ppm, the oxygen concentration is also in the atmosphere of 20 ppm to 6000 ppm on the airtight box 1a side of the hydrophobic organic liquid container 5.

The molded body 19 transferred to the transfer zone 24 passes through the hydrophobic organic liquid in the process of being transferred on the transfer zone 24, and in the process, the surface thereof is wet with the hydrophobic organic liquid and directly contacts the atmosphere. It will be in a state where it will not do. Thereafter, the molded body 19 transferred on the transport belt 24 is transferred on the transport belt 25, and the hydrophobic organic liquid container 5 is transferred by the transport belt 25.
It is transported from the inside to the atmosphere. After that, the molded body 19 is further transferred from the conveyor belt 25 to the conveyor belt 26, and in the process of being transferred on the conveyor belt 26, is transferred onto the sintering dish 27 prepared in parallel with the conveyor belt 26. The sintering dish 27 is sequentially carried into the sintering furnace 3 through the atmosphere / vacuum displacement chamber 6.

In the process in which the transfer belt 25 and the transfer belt 26 are sequentially transferred and carried into the sintering furnace 3 by the sintering plate 27 through the atmosphere / vacuum displacement chamber 6 and the sealing doors 7 and 8, The molded body 19 passes through the hydrophobic organic liquid in the process of being transported on the previous conveyor belt 24, and the surface thereof is wetted by the hydrophobic organic liquid in the process so that the molded body 19 is not in direct contact with the atmosphere. Therefore, even if it is transferred in the atmosphere, it is not particularly deteriorated and can be safely and easily carried into the sintering furnace 3.

Therefore, according to the raw material powder molding apparatus of the above embodiments, the oxygen concentration is consistently 20 p during the raw material supply process to the molding machine 13 and the subsequent raw material powder molding process.
The work is handled in an Ar gas atmosphere adjusted to pm to 6000 ppm, and the oxidation of the handled work is minimized. Moreover, the obtained molded body 19
Is directly transferred from the Ar gas atmosphere into the hydrophobic organic liquid 5a in the hydrophobic organic liquid container 5, and in the process of being transferred through the hydrophobic organic liquid 5a, its surface is wetted by the hydrophobic organic liquid 5a, Since it is brought into a state where it does not come into direct contact with, it is safely and easily carried into the sintering furnace 3 from the molding apparatus 1.

In the production method of the present invention, since the hydrophobic organic substance liquid prevents the molded body from being oxidized, it may be left for a few hours in the air and then subjected to sintering.

Next, an embodiment of the apparatus for producing a rare earth permanent magnet of the present invention, to which the above-described apparatus for forming raw material powder of the present invention is applied, will be described. FIG. 4 shows a rare earth permanent magnet manufacturing apparatus according to an embodiment of the present invention, which will be described by dividing it into six major steps A to F divided by broken lines in the figure.

A Hydrogen Grinding Process Step A raw material ingot is vacuum-melted, and the heat-treated rare earth permanent magnet raw material is first subjected to the hydrogen crushing process shown in FIG. In this example, the ingot produced by the melting method is used as the starting material, but the direct reduction diffusion method (Japanese Patent Laid-Open No. 59-219404) is used.
It is needless to say that the same can be applied to the raw materials according to No.).

The hydrogen pulverization treatment is carried out in the H ₂ pulverization treatment means 30 constituted by the H ₂ occlusion cell 31, the de-H ₂ cell 32 and the cooling cell 33. In the H ₂ storage cell 31, the ingot stores hydrogen. Hydrogen absorption can be performed at a temperature of 500 ° C. or lower under reduced pressure, normal pressure, or under pressure. The hydrogen-occluded ingot is conveyed to the H ₂ degassing cell 32, where H ₂ is removed (de-H ₂ ) to collapse and crush the ingot. This H ₂ removal treatment can be performed at a temperature of 500 to 800 ° C. and a temperature of 0.1 to 100 torr. Next, the crushed mass is conveyed to the cooling cell 33.
The cooling cell 33 is maintained in an inert atmosphere, but it is desirable to use a pressurized atmosphere in order to improve cooling efficiency.
Further, it is desirable to use Ar gas having a high specific gravity for forming the inert atmosphere in order to speed up the replacement in the cooling cell 33. The temperature in the cooling cell 33 may be kept at about room temperature. The cooled crushed mass is conveyed to the handling cell 34 which is maintained in an inert atmosphere.

B Coarse pulverizing step The pulverized lumps pulverized with hydrogen in the hydrogen pulverizing step of A are coarsely pulverized to a particle size sufficient for use in the next fine pulverizing step. The crushed lumps that have been circulated in the H ₂ crushing means 30 and conveyed toward the cell 34 are delivered to the roll crusher 40 by the trolling robot 41, and the coarse crushing processing is performed there. Powder after coarse crushing is 200-700μ
It is about m. The coarse crushing may be performed by using a crusher such as a brown mill or a jaw crusher other than the roll crusher.

In the above process, the H ₂ pulverizing means 30 has a structure in which the whole is shielded from the atmosphere, and in the process in the H ₂ pulverizing means 30, there is no chance that the raw material comes into contact with the atmosphere and contains oxygen. Absent. However, H ₂ pulverization processing means 3
In the process of being delivered from the handling cell 34 of 0 to the roll crusher 40 by the handling robot 41, conventionally, oxygen was contained due to contact with the atmosphere. Therefore, in the present invention, as shown in FIG. 1, the process of delivering the raw material from the handling cell 34 of the H ₂ pulverization processing means 30 to the roll crusher 40 by the handling robot 41 is filled with Ar gas shown by the one-dot chain line in the figure. Inert atmosphere chamber 42
Done in. In this case, the handling of delivering the raw material from the handling cell 34 of the H ₂ pulverization processing means 30 to the roll crusher 40 is performed by the handling robot 41, and since the configuration which does not particularly depend on manpower is not taken, it is indicated by a dashed line in the figure. The Ar gas atmosphere in the active atmosphere chamber 42 can be industrially performed by a known means.

C Fine Grinding Step The raw material powder coarsely crushed by the roll crusher 40 in the coarse crushing step B is conveyed by the N ₂ gas to the cyclone 50 through the conveying path 23 and is supplied to the fine crushing step C. The carrier gas and the powder are separated in the cyclone 50, and the separated powder is transferred to the jet mill 53 through the hopper 51 and the supply device 52, and the jet mill 5
The powder finely pulverized in No. 3 is conveyed by N ₂ gas through the conveying path 57a, the wind classifier 54, the conveying path 58, the cyclone 55, and the hopper 56 to the next step through the conveying path 59. In this embodiment, the powder was directly conveyed by N ₂ gas, but the powder may be filled in a container and the container may be conveyed by an inert gas such as N ₂ gas.

In the above process, the cyclone 50, the hopper 51, the supply device 52, the jet mill 53, the wind classifier 54, the cyclone 55 and the hopper 56 are N ₂ respectively.
A gas path is formed, and a transfer path 57 interposed therebetween is provided.
Also in a, 58, and 59, since the N ₂ gas is used for transportation, the raw material powder does not come into contact with the atmosphere during the processing. Since the powder having a large particle size may be contained even after pulverization by the jet mill 53, the wind force classifier 54
The powder which has not been sufficiently pulverized by the jet mill 53 is re-sorted by the jet mill 53 through the conveying path 57b indicated by a broken line in the figure.
And is crushed again.

D Mixing Step The raw material powder finely pulverized in the fine pulverizing step C is conveyed to the D mixing step by the N ₂ gas through the conveying path 59. In the mixing step D, the raw material powder is supplied from the cyclone 60 to the mixer 62 via the raw material hopper 61, while the lubricant is also supplied to the mixer 62 via the lubricant hopper 63.
The raw material powder and the lubricant are mixed in the mixer 62. Although this mixing step is for improving the moldability in the molding step which is the next step, it may be carried out after the coarse crushing step or may not be carried out in some cases.

In the above process, the cyclone 60, the raw material hopper 61, and the mixer 62 are each set in the N ₂ gas atmosphere, and the lubricant hopper 63 is also filled with the lubricant, and the atmosphere is constantly replaced by the N ₂ gas. As a result, the raw material powder is prevented from coming into contact with the atmosphere in this step.

E Forming Step The forming apparatus 1 for raw material powder of the present invention is applied to the forming step,
The inside of the airtight box 1a is set to an Ar gas atmosphere in advance, and the oxygen concentration is adjusted to be 20 ppm to 6000 ppm. The raw material powder mixed with the lubricant in the mixing step D is conveyed to the raw material tank 2 in the molding step E by N ₂ gas through the conveying path 64. In the raw material tank 2, the carrier N ₂ gas and the powder are separated, and the separated powder is supplied to the raw material receiving hopper 9 through the airtight valve 4. The raw material is stored in the raw material receiving hopper 9, is weighed by the weighing device 10, and is supplied to the powder feeding device 11 arranged on the powder feeding table 12 by a predetermined amount. Powder feeding device 11 to which raw materials are supplied
The upper and lower molds 14 of the molding machine 13 by the transfer cylinder 16,
The compact 19 obtained by molding the raw material between the upper and lower molds 14 and 15 is conveyed to the unloading zone 20 via the chute 18 and is then moved to the unloading zone 20 by the powder removing device 21. Powder is removed in the process of being transported. After that, the molded body 19 is transferred from the carry-out zone 20 through the chute 23 to the hydrophobic organic liquid container 5 and stored in the hydrophobic organic liquid container 5.
The molded body 19 transferred to the transfer belt 24 disposed therein passes through the hydrophobic organic liquid 5a in the process of being transferred on the transfer belt 24, and the surface thereof is hydrophobic in the process. The liquid becomes wet with the organic liquid and loses its direct contact with the atmosphere. After that, the molded body 19 is further transferred to the conveyor belt 25.
From the transfer belt 26 to the transfer belt 26, and in the process of being transferred on the transfer belt 26, it is transferred onto the sintering plate 27 prepared in parallel with the transfer belt 26, and sequentially through the atmosphere / vacuum displacement chamber 6 to the sintering furnace 3 It is brought in.

During the process of being carried into the sintering furnace 3 as described above, the molded body 19 is in a state where it does not come into direct contact with the atmosphere, so there is no particular change in quality even if it is transported in the atmosphere.
It is safely and easily carried into the sintering furnace 3.

F Sintering Step The sintering step F is performed in the sintering furnace 3, and the sintering furnace 3 is a continuous three-chamber sintering furnace including a preparation chamber 82, a sintering chamber 83, and a cooling chamber 84. To be done.

The atmosphere in the atmosphere / vacuum replacement chamber 6 is the atmosphere in the initial state when the molded body 19 is transported, but is replaced with a vacuum after the transportation. After the atmosphere / vacuum replacement chamber 6 is replaced with a vacuum, the molded body 19 is conveyed to the preparation chamber 82 maintained in a vacuum. After that, the compact 19 is conveyed to the sintering chamber 83 and sintered under vacuum. In the above, it is of course possible to directly transfer the compact 19 from the atmosphere / vacuum displacement chamber 6 to the sintering chamber 83 without providing the preparation chamber 82. However, if the compact 19 is retained in the preparatory chamber 82 maintained in vacuum, the compact 19 can be transferred to the sintering chamber 83 even if the atmosphere in the atmosphere / vacuum displacement chamber 6 is in the atmospheric state. And work efficiency is improved. That is, without the preparation room 82,
If the compact 19 is conveyed to the sintering chamber 83 in a state where the vacuum displacement chamber 6 is in the atmosphere, the temperature inside the sintering chamber 83 drops, and the vacuum state needs to be released again to evacuate again, thus lowering work efficiency. . The sintered body that has been sintered in the sintering chamber 83 is conveyed to the cooling chamber 84 and cooled. Although the cooling chamber 84 is initially in a vacuum state, Ar gas is introduced after carrying in the sintered body.

Therefore, according to the apparatus for producing a rare earth permanent magnet of the above embodiment, the rare earth permanent magnet having an extremely small oxygen content can be efficiently and safely produced. Sintering can be performed in an N ₂ gas or Ar gas atmosphere, but N ₂ gas may nitride the sintered body and reduce magnetic properties, and since Ar gas is expensive, it is vacuum sintered. Is desirable.

The apparatus of this embodiment is provided with a compressor 86 for recycling gas for forming an inert atmosphere. That is, the gas recovered from the cyclones 50, 55, 60, 2 to the compressor 86 via the recovery pipe 87 is supplied again via the supply pipe 88.

(Embodiment 1) Next, by using a raw material powder molding apparatus of one embodiment of the present invention shown in FIGS. The powder was molded, the obtained molded body was dipped in N-hexane, allowed to stand for 30 minutes and then sintered, and the oxygen content of the sintered body was measured. As a result, the oxygen content is 2200p
It became pm. As Comparative Example 1, raw material powders having the same composition were molded by the molding apparatus shown in FIGS. 1 to 3, the resulting molded body was sintered, and the oxygen content of the sintered body was measured. In the comparative example, sintering was performed after leaving it in the atmosphere for 5 minutes without immersing it in N-hexane. As a result, the oxygen content is 8000p
It became pm. The forming of the raw material powder was performed in both the example and the comparative example 1 by keeping the inside of the airtight box 1a in an Ar atmosphere and setting the oxygen concentration to 20 ppm. In the comparative example not immersed in the hydrophobic organic liquid, the oxygen content is as high as 8000 ppm, but according to the production method of the present invention, the oxygen content is 22
It can be seen that a sintered body as small as 00 ppm can be obtained.

(Embodiment 2) Next, the raw material powder was actually molded by the raw material powder molding apparatus of one embodiment of the present invention shown in FIGS. 1 to 3, and the obtained molded body was immersed in mineral oil. Sintering was performed and the oxygen content in the sintered body was measured. The results are shown in Table 1. The raw material powder was molded by setting various oxygen concentrations in the airtight box 1a.

[0047]

[Table 1]

As shown in Table 1, it is understood that as the oxygen concentration in the airtight box 1a increases, the oxygen content of the sintered body obtained by sintering the obtained molded body increases.

Next, the result of actually producing a rare earth magnet by the apparatus for producing a rare earth magnet according to the embodiment of the present invention shown in FIG. 4 will be described together with a comparative example.

(Example 3) 29.5% by weight of Nd-
An alloy ingot was obtained by weighing so as to obtain a final sintered body of 1.5% Dy-1% B-1% Nb-remaining Fe and melting it in an inert (Ar) gas. Using the alloy ingot as a raw material, a permanent magnet was manufactured using the manufacturing apparatus shown in FIG. The average particle diameter of the raw material powder for molding was set to 3.4 μm, the molding pressure in the molding machine 13 in the molding step E was 2.9 t / cm ^2, and molding was performed in a magnetic field of 16 KOe. Further, the inside of the airtight box 1a accommodating the molding machine 13 was an Ar gas atmosphere, and the oxygen concentration thereof was 800 ppm. The vacuum atmosphere in the sintering step F was 10 ⁻⁴ Torr, the sintering temperature was 1100 ° C., the sintering was performed for 2 hours, and then the temperature was 1.5 ° C.
It cooled at the cooling rate of / min. Mineral oil was used as the hydrophobic organic substance. After cooling, it was heated again, subjected to an aging treatment at 690 ° C. for 2 hours in an Ar gas atmosphere, rapidly cooled to room temperature, processed to 10 × 10 × 10 mm, and then subjected to measurement of magnetic properties.

(Comparative Example 2) Others were the same as in Example 3, except that the atmosphere of the coarse crushing step B and the molding step E shown in FIG. 4 was atmospheric air, and the raw material was routed between the steps A to F in the atmospheric air. Then, a permanent magnet was manufactured, and the magnetic characteristics were evaluated in the same manner as in Example 3. Table 2 shows the results of the above Example 3 and Comparative Example 2. [0052]

[Table 2]

As shown in Table 2, the permanent magnets obtained according to the examples of the present invention show extremely good magnetic characteristics as compared with those of the comparative examples. The above example is 29.5% N
Although a magnet having a composition of d-1.5% Dy-1% B-1% Nb-remaining Fe was described, a part of Nd was Pr, Ce.
Other rare earth elements such as Fe may be substituted, and part of Fe may be substituted with Co or Ni. Furthermore, A
Elements such as 1, Ti, Cr, and Ga can be added.

[0054]

As described above, according to the manufacturing method and the manufacturing apparatus of the present invention, the molded body can be easily handled and oxidation can be prevented. In addition, the oxygen content of the rare earth permanent magnet can be reduced thereby.

[Brief description of drawings]

FIG. 1 is a schematic side view of a raw material powder molding apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic plan view of a raw material powder molding apparatus of the embodiment shown in FIG.

FIG. 3 is a partial perspective view showing a molding machine portion of the raw material powder molding apparatus of the embodiment shown in FIG.

FIG. 4 is a schematic view of an apparatus for manufacturing a rare earth-based permanent magnet of the present invention.

[Explanation of Codes] 1 ... Molding device, 2 ... Raw material tank, 3 ... Sintering furnace, 5 ... Hydrophobic organic liquid container, 5a ... Hydrophobic organic liquid, 1a ... Airtight box, 6 ... Atmosphere
Vacuum displacement chamber, 13 ... Molding machine, 14 ... Upper mold, 1
5 ... Lower mold, 16 ... Transfer cylinder, 17 ...
Airtight flange A ... Hydrogen crushing process, B ... Coarse crushing process, C.
..Fine grinding process, D ... mixing process, E ... molding process, F ... sintering process

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication C22C 38/00 303 D H01F 1/053 1/08 (72) Inventor Kazuo Hayakawa Mikkajiri, Kumagaya-shi, Saitama Prefecture 5200 Hitachi Metals Co., Ltd.Kumagaya Plant

Claims (7)

[Claims] 1. A method for producing a rare earth magnet having a forming step, which comprises immersing the formed body obtained by the forming step in a hydrophobic organic liquid. 2. The method for producing a rare earth magnet according to claim 1, wherein the molded body molded in an inert atmosphere is immersed in a hydrophobic organic liquid. 3. The oxygen concentration in the inert atmosphere is 20 ppm.
The method for producing a rare earth magnet according to claim 2, wherein the content is 6000 ppm. 4. A method for manufacturing a rare earth magnet having a hydrogen pulverization treatment step, a coarse pulverization treatment step, a fine pulverization treatment step, a molding step, and a sintering step, wherein the coarse pulverization treatment step and the fine pulverization treatment step are performed. And the molding step is performed in an inert atmosphere, the routing between the steps before the sintering step is performed in an inert atmosphere, and the molded body obtained in the molding step is a hydrophobic organic liquid. A method for producing a rare earth magnet, which comprises subjecting to a sintering step after being immersed in the magnet. 5. A molding apparatus for raw material powder, comprising a molding machine having an upper mold and a lower mold, and a hydrophobic organic liquid container holding a hydrophobic organic liquid in which the molded body is immersed. 6. The raw material powder molding apparatus according to claim 5, wherein the molding unit of the molding machine is held in an inert atmosphere. 7. A hydrogen pulverization treatment means, a coarse pulverization treatment means continuous with the hydrogen pulverization treatment means, a fine pulverization treatment means continuous with the coarse pulverization treatment means, and a molding means continuous with the fine pulverization treatment means. In a rare earth magnet manufacturing apparatus having a sintering means continuous to the forming means, the coarse pulverizing means, the fine pulverizing means, and the forming means are arranged under an inert atmosphere, The hydrogen pulverizing means, the coarse pulverizing means, the fine pulverizing means,
A handling means under an inert atmosphere is provided between the molding means and a carrying means for carrying the molded product molded by the molding machine into the hydrophobic organic liquid in the hydrophobic organic liquid container in a state where the outside air is blocked. An apparatus for manufacturing a rare earth magnet, characterized in that the shaping means is constituted by the shaping apparatus.