JPH06346102A - Raw powder compactor and method for producing rare-earth magnet and device therefor - Google Patents

Abstract

PURPOSE:To provide an industrial raw powder compactor capable of reducing the oxygen content of a rare-earth permanent magnet and capable of improving the practical quality of a rare-earth permanent magnet. CONSTITUTION:The oxygen concn. in an airtight box 1a is kept at 20-6000ppm, the raw powder supplied to a raw powder receiving hopper 9 from a raw material tank 2 through an airtight valve 4 is weighed by a weighing device 10 and supplied in specified amt. to a powder feeder 11 arranged on a powder feed table 12. When the powder feeder 11 is set at a specified position, upper and lower dies 14 and 15 are operated. The obtained compact 19 is conveyed on a discharge band 20 through a chute 18, depowdered by a device 21, extruded by a feed cylinder toward the charge passage of a sintering dish traveling in parallel with the discharge band 20 and transferred on the sintering dish. The compact 19 is conveyed on the charge passage toward a sintering furnace 3 along with the sintering dish.

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 not containing Co 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 are improved as the oxygen content is suppressed to a low level.

Therefore, studies have been made so far on the Nd-Fe-B system permanent magnets for suppressing the oxygen content thereof to a low level. As a result of such research, the present applicant has proposed a method for molding a permanent magnet alloy powder in which the raw material powder is molded in an inert atmosphere in Japanese Patent Laid-Open No. 61-287107. The molding method of the permanent magnet alloy powder proposed by the present applicant is effective as a method for reducing the oxygen content of the Nd-Fe-B system permanent magnet.

[0004]

However, conventionally, when the raw material powder is molded in an inert atmosphere, the entire molding machine is surrounded by a box so that the inside is in an inert atmosphere. It was done by a method such as making it an active atmosphere. Since this maintains a wide range in an inert atmosphere, a large amount of inert gas is required, leading to high costs, and there are problems such as difficulty in lowering the oxygen concentration in the atmosphere, making industrial implementation difficult. for that reason,
In order to further reduce the oxygen content of the Nd-Fe-B based permanent magnet, it was still unsatisfactory, 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 it is possible to thoroughly reduce the oxygen content of rare earth permanent magnets such as Nd-Fe-B system permanent magnets, and at the same time industrially. It is an object of the present invention to provide a raw material powder molding apparatus capable of various implementations and improving the practical quality of a rare earth permanent magnet, a method for manufacturing a rare earth magnet using the same, and an apparatus therefor.

[0006]

DISCLOSURE OF THE INVENTION The present inventors have conducted various studies to achieve the above-mentioned objects of the present invention, and carried out the invention described in JP-A-61-287107 proposed by the present applicant. The present invention has been accomplished by succeeding in developing a molding apparatus for raw material powder that enables the above-mentioned material, and by contriving a method for manufacturing a rare earth magnet to which the molding apparatus is applied and the apparatus therefor. That is, the raw material powder molding apparatus of the present invention is equipped with an upper mold or a lower mold, at least one of which is relatively movable, on a base having a communication hole, and the communication hole of the base and the airtight box are provided inside the base. It is an apparatus for forming raw material powder in which an airtight box is connected to the base in a series. With such a configuration, the molding part of the molding machine (the upper and lower mold contact surfaces of the molded body and the space between them) can be formed without surrounding the entire molding machine: FIG.
Since the molding part 29) is held in an airtight state inside the substrate and the airtight box, a desired atmosphere can be easily obtained, and the oxygen concentration can be lowered to 20 ppm to 6000 ppm and can be controlled to be constant. .

When the airtight box is connected to the base body and the communication hole portion of the base body and the airtight box are arranged in series inside the airtight box, the airtight box and the base body can be attached via the airtight flange. The airtight flange is formed integrally with the airtight box, while the base body is formed into a box shape having communication holes at the front and rear, and the airtight flange of the airtight box is brought into contact with the front and rear side surfaces of the base, so that the airtight box forms the airtight flange. It can be connected to the base body through. The airtight box is equipped with a sealable door that can be opened and closed, and even when the raw material powder and the molded body are conveyed, the outside air hardly flows into the airtight base body and the airtight box. Further, in the airtight box, a powder feeding device for supplying the raw material powder to the die, a powder removing device for dropping the powder attached to the molded body, and the like can be stored.

The method for producing a rare earth magnet according to the present invention is the method for producing 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. The pulverization process and the fine pulverization process are performed in an inert atmosphere, and at least one of the communicating holes of the base is equipped with an upper mold or a lower mold capable of relatively moving, and the base is provided with an airtight box. It is characterized in that they are connected to each other, and the communicating hole portion of the base and the airtight box perform a molding process in the inside thereof by a series of molding devices, and the routing between the processes is carried out in an inert atmosphere.

In the present application, the inert atmosphere means N ₂ , C
An atmosphere formed by a gas having low reactivity such as O ₂ , Ar, and He.

It is desirable that the powder is handled during the steps from the coarse crushing process to the molding by inert gas transportation.
In the present application, the inert gas transfer means N ₂ , CO ₂ , Ar,
It means that the powder is conveyed by an air flow of a gas having low reactivity such as He.

In addition, the apparatus for producing a rare earth magnet of the present invention is
Hydrogen pulverization processing means, coarse pulverization processing means continuous to the hydrogen pulverization processing means, fine pulverization processing means continuous to the coarse pulverization processing means, and molding means continuous to the fine pulverization processing means,
In a rare earth magnet manufacturing apparatus having a sintering means continuous to the forming means, the coarse pulverization processing means and the fine pulverization processing means are arranged under an inert atmosphere, and A handling means under an inert atmosphere is provided therebetween, and a base having a communication hole is equipped with an upper mold or a lower mold in which at least one is relatively movable, and the base is connected to an airtight box, The communication hole and the airtight box constitute a series of molding devices inside.

The inside of the airtight box is filled with an atmosphere of an inert gas such as Ar or N ₂ , and the oxygen concentration is 20 ppm to 600 ppm.
It is good to set it to 0 ppm. If it exceeds 6000 ppm, the object to be molded contains excessive oxygen during the molding process, and the quality of the obtained rare earth permanent magnet becomes unsatisfactory. On the other hand, it is industrially extremely difficult to set the oxygen concentration to less than 20 ppm, and even if such an oxygen concentration can be realized, the actual profit commensurate with the cost required therefor cannot be obtained.

It is preferable that the powder handling means between each step from the coarse crushing processing means to the molding means is an inert gas carrier, and the vacuum sintering means is an inert atmosphere continuous with the molding means. Efficiency can be improved by including the vacuum displacement chamber, the sintering chamber, and the cooling chamber.

[0014]

Therefore, according to the apparatus for molding raw material powder of the present invention, since the molding part of the molding machine is surrounded by the base and the airtight box, the range of airtight holding is narrow. Therefore, the molding part can be easily maintained in the airtight state, and the raw material powder can be molded under the completely airtight state. Further, since the range of airtight holding is narrow, the atmosphere can be held with a small amount of inert gas, and the cost can be reduced. Further, according to the method and apparatus for manufacturing a rare earth magnet of the present invention, the steps from the hydrogen pulverizing step to the step before sintering are consistently carried out under an inert atmosphere, and the routing between the steps is carried out under an inert atmosphere. In addition to the above, the forming means is a forming device in which the forming part is placed in an airtight box, so the raw material powder can be formed in a completely airtight state, and sintering is performed after hydrogen pulverization processing. -It is possible to obtain a rare earth permanent magnet having a very low oxygen content and good magnetic properties, in which atmospheric contact of the work is completely prevented until cooling is completed.

[0015]

EXAMPLE A raw powder molding apparatus according to an example 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 perspective view 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 part 29 of the molding machine 13 disposed on the base and provided on the base is airtightly held by the airtight box 1a.
The inside of the airtight box 1a is made to be an Ar atmosphere 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 does not come into contact with the atmosphere. On the other hand, the airtight box 1a and the sintering furnace 3 are connected via an inert atmosphere / vacuum displacement chamber 6. A sealing door 7 is provided between the inert atmosphere / vacuum displacement chamber 6 and the airtight box 1a, and a sealing door 8 is provided between the inert atmosphere / vacuum displacement chamber 6 and the sintering furnace 3. Is provided.

A raw material powder receiving hopper 9 is arranged in the airtight box 1a below the airtight valve 4 on the raw material tank 2 side, and the raw material powder receiving hopper 9 flows down from the raw material tank 2 via the airtight valve 4. The raw material to be received is received. A weighing device 10 is attached to the raw material powder receiving hopper 9, and a powder feeding device 11 is provided adjacent to the weighing device 10 on the discharge side of the weighing device 10. The powder feeding device 11 is arranged on a powder feeding table 12, and the powder feeding table 12 is mounted on the molding machine 13.
The upper and lower molds 14 and 15 are extended and arranged. 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 and reciprocates on the powder feeding table 12 from a position between the upper and lower molds 14 and 15 to a lower position of the weighing device 10. Can be moved.

As shown in FIG. 3, the upper and lower molds 14 and 15 of the molding machine 13 are mounted on the base body 1b, and the base body 1b is attached to the airtight box 1a by an airtight flange 17.
, And as a result, the airtight box 1a and the base body 1b are connected in series inside and in an airtight state to the outside. 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 its four sides. On the other hand, the base body 1b is formed in a box shape having a communication hole portion 161 in the front and rear, and the airtight flange 17 of the airtight box 1a is brought into contact with the front and rear side surface portions 162 thereof, and a screw is screwed into the stop hole 171 so that The airtight box 1a is connected to the base body 1b in an airtight state with respect to the outside 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 molded body 19 on the carry-out zone 20 and generates an alternating magnetic field, so that the molded body on the carry-out zone 20 is dedusted. Further carry-out zone 2
On the upper surface of 0, a guide 22 is arranged from above the powder removing device 21 toward the sintering furnace 3, and a distribution cylinder 23 is installed at the end of the guide 22 on the side of the sintering furnace 3. The distribution cylinder 23 and the guide 22 constitute an aligning device for the powder compacts 19.

An air / inert atmosphere replacement chamber 24 is provided on the side of the airtight box 1a, and a transfer path 26 for the sintering plate 25 is provided outside the airtight box 1a via the air / inert atmosphere replacement chamber 24. It is continuously extended from the inside.
Air / inert atmosphere replacement chamber 24 and airtight box 1a
A sealing door 27 is arranged at a connecting portion with and a sealing door 28 is arranged at a connecting portion between the atmosphere / inert atmosphere substitution chamber 24 and the carry-in passage 26 outside the airtight box 1a. Further, the carry-in passage 26 in the airtight box 1a is guided to an inert atmosphere / vacuum displacement chamber 6 provided between the airtight box 1a and the sintering furnace 3 so as to run in parallel with the carry-out zone 20, and the inert gas is introduced. It is extended in the sintering furnace 3 through the atmosphere / vacuum displacement chamber 6.

Therefore, according to the raw material powder molding apparatus of the above-mentioned 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, first, the raw material powder is supplied from the raw material tank 2 to the raw material powder receiving hopper 9 through the airtight valve 4. The raw material powder is stored in the raw material powder 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. A state in which the powder feeding device 11 to which the raw material powder has been fed is transported between the upper and lower molds 14 and 15 of the molding machine 13 by the transport cylinder 16 and set at a predetermined molding position, and the powder feeding device 11 is set at a predetermined position. Then, the upper and lower molds 14 and 15 are actuated to obtain a molded body 19. The obtained compact 19 is used for the powder feeding device 11
Then, it is pushed out by the transfer cylinder 16 and transferred to the chute 18.

The compact 19 obtained by molding the raw material powder 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 on the surface of 0. Such molded body 19
Moves along the guide 22 and is conveyed to a position close to the distribution cylinder 23. The compact 19 conveyed to the position close to the distribution cylinder 23 is pushed out by the distribution cylinder 23 toward the carry-in path 26 of the sintering dish 25 that runs in parallel with the carry-out zone 20, and is transferred onto the sintering dish 25.

Next, the molded body 1 transferred onto the sintering dish 25
9 is conveyed with the sintering tray 25 on the carry-in path 26 toward the sintering furnace 3. At that time, when carrying in from the airtight box 1a to the sintering furnace 3, the sealing doors 7 and 8 arranged in the inert atmosphere / vacuum displacement chamber 6 are opened and closed by the following procedure. First, the sealing door 7 is opened in a state where the inside of the inert atmosphere / vacuum substitution chamber 6 is set to the same atmosphere as the airtight box 1a, and the sintering tray 25 and baking are performed in such a state that the sealing door 7 is opened. The molded body 19 placed on the tray 25 is carried into the inert atmosphere / vacuum displacement chamber 6. After the sintering tray 25 and the molded body 19 placed on the sintering tray 25 have been carried into the inert atmosphere / vacuum displacement chamber 6, the closed door 7 is closed and the inert atmosphere
The inside of the vacuum substitution chamber 6 is adjusted to the same vacuum atmosphere as that in the sintering furnace 3. After that, the sealing door 8 arranged between the inert atmosphere / vacuum displacement chamber 6 and the sintering furnace 3 is opened, and the sintering dish carried into the inert atmosphere / vacuum displacement chamber 6 in that state. 25 and the molded body 19 placed on the sintering dish 25 are carried into the sintering furnace 3 and subjected to the sintering process. After that, the sealing door 8 arranged between the inert atmosphere / vacuum displacement chamber 6 and the sintering furnace 3 is closed, and the inside of the inert atmosphere / vacuum displacement chamber 6 becomes the same atmosphere as the airtight box 1a. Is adjusted. By repeating the above process, the airtight box 1
The compact 19 is continuously carried into the sintering furnace 3 from a through the inert atmosphere / vacuum displacement chamber 6.

On the other hand, the sintering tray 25 on the carry-in path 26 is carried into the airtight box 1a by the following procedure. First, the airtight box 1a is opened, and the airtight box 1a is opened, and the airtight box 1a is opened.
The sintering tray 25 on the carry-in passage 26 is replaced with the atmosphere / inert atmosphere replacement chamber 24 with the closed door 27 disposed between
It is carried in, and then the sealing door 28 is closed. In this state, the atmosphere / inert atmosphere replacement chamber 24 is adjusted to have the same atmosphere as the airtight box 1a, and then the sealing door 27 is opened and the sintering tray 25 is carried into the airtight box 1a.
After that, the sealing door 27 arranged between the atmosphere / inert atmosphere replacement chamber 24 and the airtight box 1a is closed, and the carry-in passage 26 outside the airtight box 1a is connected to the atmosphere / inert atmosphere replacement chamber 24. The sintering dish 25 on the carry-in path 26 is carried into the atmosphere / inert atmosphere replacement chamber 24 with the closed door 28 provided in the part opened, and the atmosphere / inert atmosphere is obtained by repeating the above process. The sintering tray 25 is continuously carried into the airtight box 1a through the atmosphere replacement chamber 24.

Therefore, according to the raw material powder molding apparatus of the above embodiment, the raw material supply process to the molding machine 13, the subsequent raw material powder molding process, and the carrying process of the molded body to the sintering furnace 3 after molding. Oxygen concentration is consistently 20ppm to 60 throughout
The work is handled in an Ar gas atmosphere adjusted to be 00 ppm, and the oxidation of the work to be handled is suppressed to the minimum.

Next, an embodiment of the apparatus for producing a rare earth permanent magnet of the present invention to which the above-mentioned apparatus for forming raw material powder 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 further heat-treated, and the 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 composed of the H ₂ storage 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 mass pulverized with hydrogen in the hydrogen pulverizing step of A is 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 pulverization processing means 30 has a structure in which the whole is shielded from the atmosphere, and in the process in the H ₂ pulverization processing 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 43, 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 pulverized in the pulverizing step of C is conveyed to the mixing step of D by 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 Molding Step The material powder molding apparatus 1 of the present invention is applied to the molding 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 cyclone 70 in the molding step E by N ₂ gas through the conveying path 64. Transport N _{2 in} cyclone 70
The gas and the powder are separated, and the separated powder is supplied to the raw material powder receiving hopper 9 through the airtight valve 4. The raw material powder is stored in the raw material powder 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. The powder feeding device 11 to which the raw material powder is supplied is conveyed by the conveying cylinder 16 between the upper and lower molds 14 and 15 of the molding machine 13, and a molded body obtained by molding the raw material powder between the upper and lower molds 14 and 15. 19 is conveyed to the unloading zone 20 via the chute 18 and is dedusted in the process of being conveyed on the unloading zone 20 by the dedusting device 21.
Then, it is conveyed toward the sintering furnace 3 through the inert atmosphere / vacuum displacement chamber 6 and the closed doors 7 and 8.

F Sintering Step The compact formed in the forming step E is conveyed to the sintering step F on the conveying path 26. The sintering step F is performed in the sintering furnace 3 continuous to the airtight box 1a through an inert atmosphere / vacuum displacement chamber 6, and the sintering furnace 3 is provided in the preparation chamber 8
2, a continuous three-chamber sintering furnace composed of a sintering chamber 83 and a cooling chamber 84.

The inert atmosphere / vacuum replacement chamber 6 is in an inert atmosphere in the initial state when the molded body 19 is transferred, but is replaced with a vacuum after the transfer. After the inert atmosphere / vacuum replacement chamber 6 is replaced with a vacuum, the molded body 19 is transferred to the preparation chamber 82 maintained in a vacuum. Thereafter, the compact 19 is placed in the sintering chamber 83.
And then sintered under vacuum. In the above, it is of course possible to convey the compact 19 directly from the inert 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 that is maintained in a vacuum, the compact 19 is transferred to the sintering chamber 83 even if the inert atmosphere / vacuum displacement chamber 6 is in the inert atmosphere. The work efficiency can be improved. That is, without the preparation chamber 82, the temperature in the sintering chamber 83 that conveys the compact 19 to the sintering chamber 83 in the state of the inert atmosphere / vacuum substitution chamber 6 in the inert atmosphere is lowered, and the vacuum state is released. Therefore, it is necessary to evacuate again, which lowers 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.

The compact 19 and the sintered body in the continuous three-chamber sintering furnace 3 are conveyed along the conveying path 26. The transport path 26 is
A transfer path 26a penetrating the continuous three-chamber sintering furnace 3 from the airtight box 1a and a path to the atmosphere after passing through the continuous three-chamber sintering furnace 3 and then being circulated again in the airtight box 1a. The transport path 26b is arranged. The transfer path 26b and the transfer path 26a are provided with an atmosphere / inert atmosphere replacement chamber 24 arranged on the side of the airtight box 1a.
Connected by.

The molded body 19 placed on the sintering tray 25 on the transfer path 26a in the airtight box 1a has the inert atmosphere / vacuum replacement chamber 6 to the cooling chamber 84 along the transfer path 26a.
Are sequentially transported. The sintered body discharged from the cooling chamber 84 is conveyed along the conveying path 26b and is conveyed at a predetermined position to the conveying path 26b.
b Transferred outside. Further, the sintered dish 25 from which the sintered body has been removed advances along the transfer path 26b and is carried into the atmosphere / inert atmosphere replacing chamber 24. After loading, the atmosphere in the atmosphere / inert atmosphere replacement chamber 24 is replaced with the atmosphere by an inert atmosphere. After the replacement, the sintering tray 25 advances through the airtight box 1a along the conveying path 26a, mounts the compact 19 and enters the continuous three-chamber sintering furnace 3. As described above, the circulation / conveyance of the molded body / sintered body through the conveyance path 26 is continued.

Therefore, according to the rare earth permanent magnet manufacturing apparatus of the above embodiment, it is possible to efficiently manufacture a rare earth permanent magnet having an extremely small oxygen content. 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 cyclone 50, 55, 60, 70 to the compressor 86 via the recovery pipe 87 is
It is supplied again via the supply pipe 88.

Example 1 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 sintered, The oxygen content of 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.

[0043]

[Table 1]

As shown in Table 1, it can be seen 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 2) 30% Nd-1% D in% by weight
An alloy ingot was obtained by weighing so as to obtain a final sintered body of y-1% B-1% Nb-1% Al-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 3.1 μm, the molding pressure in the molding machine 13 in the molding step E was 1.0 t / cm ^2, and molding was performed in a magnetic field of 17 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 650 ppm. In the sintering step F, the vacuum atmosphere was set to 10 ⁻⁴ Torr, the sintering temperature was set to 1080 ° C., and the sintering was performed for 2 hours.
It was cooled at a cooling rate of in. After cooling, heat again, Ar
Aging treatment was performed at 680 ° C. for 2 hours in a gas atmosphere, followed by rapid cooling to room temperature, processing to 10 × 10 × 10 mm, and measurement of magnetic properties.

Comparative Example The same as Example 2 except that the atmosphere of the coarse pulverization step B and the molding step E shown in FIG. 4 was the atmosphere, and the raw materials were laid out in the atmosphere between the steps A to F. A permanent magnet was manufactured, and the magnetic characteristics were evaluated in the same manner as in Example 2. Table 2 shows the results of Example 2 and Comparative Example described above.

[0048]

[Table 2]

As shown in Table 2, the permanent magnets obtained according to the examples of the present invention exhibit extremely good magnetic characteristics as compared with those of the comparative examples. In the above example, 30% Nd-
A magnet having a composition of 1% Dy-1% B-1% Nb-2% Al-remaining Fe was described, but a part of Nd was Pr, C.
Other rare earth elements such as e may be substituted, or part of Fe may be substituted with Co or Ni. Furthermore, A
Elements such as 1, Ti, Cr, and Ga can be added.

[0050]

As described above, according to the raw material powder molding apparatus of the present invention, since the molding portion is kept airtight by the airtight box, the amount of oxygen in the atmosphere can be controlled without requiring a large amount of inert gas. Allows a drop. By using the molding apparatus of the present invention, it is possible to thoroughly reduce the oxygen content in the molding process of the rare earth permanent magnet raw material powder such as Nd-Fe-B system permanent magnet and improve the practical quality of the rare earth permanent magnet. it can.

Further, according to the method for producing a rare earth magnet of the present invention to which the raw material powder molding apparatus of the present invention is applied, the coarse pulverizing means and the fine pulverizing means are arranged in an inert atmosphere. In addition, since the routing means under an inert atmosphere is provided between the respective means, and the molding means is a molding machine in which the molding machine is arranged in the airtight box, the rare earth magnet is manufactured. Since the raw material after the hydrogen pulverization treatment is completely prevented from coming into contact with the atmosphere until it becomes a sintered body, the oxygen content of the rare earth permanent magnet can be thoroughly reduced, and industrial implementation is possible. The excellent effect that the practical quality of the rare earth permanent magnet can be improved is exhibited.

[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.

3 is a perspective view of a raw material powder molding apparatus of the embodiment shown in FIG. 1. FIG.

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

[Explanation of symbols]

1 ... Molding device, 2 ... Raw material tank, 3 ... Sintering furnace, 1a ... Airtight box, 1b ... Base body, 6 ...
・ Inert atmosphere / vacuum replacement chamber, 13 ・ ・ ・ Molding machine, 1
4, 15 ... Mold, 16 ... Transfer cylinder, 161
... Communication holes, 162 ... Front and rear side parts, 17 ...
・ Airtight flange, 24 ... Atmosphere / inert atmosphere substitution chamber, 26 ... Conveyance path, 30 ... H ₂ pulverization processing means,
31 ... H ₂ storage cell, 32 ... de-H ₂ cell, 33 ...
..Cooling cell, 34 ... Handling cell, 40 ... Roll crusher, 41 ... Handling robot, 42
・ ・ ・ Inert atmosphere room, 50 ・ ・ ・ Cyclone, 51 ・
..Hopper, 52 ... Feeding device, 53 ... Jet mill, 54 ... Wind power classifier, 55 ... Cyclone, 56 ... Hopper, 57 ... Conveyance path, 58 ...
・ Transport path, 59 ・ ・ ・ Transport path, 60 ・ ・ ・ Cyclone,
61 ... Raw material hopper, 62 ... Mixer, 63 ...
・ Lubricant hopper, 64 ... Transport path, 71 ... Hopper, 72 ... Weighing machine, 73 ... Molding machine, 74 ...
・ Powder feeder, 75 ... Mold, 76 ... Mold take-out machine, 77 ... Transport device, 78 ... Inert atmosphere chamber,
82 ... Preparation room, 83 ... Sintering room, 84 ... Cooling room, A ... Hydrogen crushing process, B ... Coarse crushing process,
C ... fine pulverization process, D ... mixing process, E ... molding process, F ... sintering process.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kimiho Uchida 5200 Mikkajiri, Kumagaya-shi, Saitama Hitachi Metals Co., Ltd. Kumagaya Plant

Claims (7)

[Claims] 1. A base having a communication hole is equipped with an upper mold or a lower mold, at least one of which is relatively movable, so that the communication hole of the base and the airtight box form a series therein. An apparatus for forming raw material powder, characterized in that an airtight box is connected to a substrate. 2. The apparatus for molding raw material powder according to claim 1, wherein the oxygen concentration inside the base and the airtight box is 20 ppm to 6000 ppm. 3. The apparatus for molding raw material powder according to claim 1, wherein the airtight box is attached to the base body via an airtight flange. 4. The airtight flange is formed integrally with the airtight box, while the base body is formed into a box shape having communication holes at the front and rear, and the airtight flange of the airtight box is brought into contact with the front and rear side portions thereof. The apparatus for molding raw material powder according to claim 3, wherein the airtight box is connected to the base body through an airtight flange. 5. A method for manufacturing a rare earth magnet, which comprises 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. In an inert atmosphere, the communication hole of the base body is equipped with an upper mold or a lower mold, at least one of which is relatively movable, and an airtight box is connected to the base body. A method of manufacturing a rare earth magnet, characterized in that a molding process is performed by a molding device having a series of holes and an airtight box, and the routing between the processes is performed in an inert atmosphere. 6. The oxygen concentration in the airtight box is 20 p.
The method for producing a rare earth magnet according to claim 5, wherein the content is pm to 6000 ppm. 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 comprising a sintering means continuous to the forming means, the coarse pulverization processing means and the fine pulverization processing means are arranged under an inert atmosphere, and In addition to being provided with a handling means under an inert atmosphere,
At least one of a base having a communication hole is equipped with an upper mold or a lower mold capable of moving relatively, and an airtight box is connected to the base, and the communication hole of the base and the airtight box are connected in series inside the base. The apparatus for manufacturing a rare earth magnet, which is a forming apparatus.