JP2000303107A - Hydrogenation granulating apparatus for rare-earth magnetic material, and manufacture of rare-earth magnetic material powder and magnet using the apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the oxidation of a material, while safely and efficiently performing a hydrogenation granulating treatment stage for a rare-earth magnetic material and a subsequent cooling stage, and to improve magnetic properties. SOLUTION: In this hydrogenation granulating apparatus 10 for performing hydrogenation granulating treatment of a rare-earth magnetic material, an outlet chamber 12 is provided in front of an outlet hole 16 of a furnace body 14, and inert gas is fed into the chamber 12. When the rare-earth magnetic material after hydrogenation milling is taken out and moved to a conveyance device 26, the magnetic material can be hereby prevented from coming into contact with the air. Conveyance, after hydrogenation milling, and cooling are also performed in an inert gas, and the raw material in a high temperature state can be prevented from being brought into contact with the air and from resultantly being oxidized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrogen pulverizing apparatus for a rare earth magnetic material, a method of producing a rare earth magnetic material powder and a method of producing a magnet, which are subjected to hydrogen pulverization using the apparatus.

[0002]

2. Description of the Related Art Rare earth sintered magnets are produced through a sintering step and an aging step after press forming an alloy powder formed by pulverizing a magnetic alloy. At present, two types of rare earth sintered magnets, a samarium / cobalt magnet and a neodymium / iron / boron magnet, are widely used in various fields. Among them, neodymium / iron / boron magnets (hereinafter referred to as "RT-
(M) -B magnet ". R is a rare earth element containing Y, T is iron, or a transition metal element which partially substitutes iron and iron, M is an additional element, and B is boron. ) Shows the highest magnetic energy product among various magnets and is relatively inexpensive, so it is actively used in various electronic devices. As the transition metal contained in T, for example, Co is used.

[0003] Conventionally, in pulverizing an alloy for an RT- (M) -B-based magnet with hydrogen, a magnetic material powder as a raw material is treated with S
The primary pulverization has been performed by filling a container made of stainless steel such as US304 or the like and executing the occlusion / release of hydrogen in a hydrogen furnace.

[0004] There are roughly two types of methods for producing this rare earth alloy. The first method is an ingot casting method in which a molten metal of a raw material alloy is put into a mold and cooled relatively slowly. The second method is to melt the alloy in a single roll, a twin roll,
This is a quenching method typified by a strip casting method or a centrifugal casting method in which a solidified alloy thinner than an ingot alloy is produced from a molten alloy by rapidly cooling by contacting with a rotating disk or a rotating cylindrical mold.

[0005] RT- (M)-produced by the quenching method
The thickness of the alloy for the B-based magnet is in a range of 0.03 mm or more and 10 mm or less. The molten alloy begins to solidify from the contact surface of the cooling roll (roll contact surface), and crystals grow in the thickness direction from the roll contact surface in a columnar shape. As a result, the rapidly solidified alloy made by a strip casting method or the like, the minor axis size is 5μm or more longitudinal size 0.1μm or 100μm or less 500μm following R ₂ T ₁₄ B crystal phase, R ₂ T ₁₄ It has a structure containing an R-rich phase dispersed and present at the grain boundaries of the B crystal phase. The R-rich phase is a nonmagnetic phase in which the concentration of the rare earth element R is relatively high, and its thickness (corresponding to the width of the grain boundary) is 10 μm or less.

[0006] The quenched alloy is an alloy (ingot alloy) produced by a conventional ingot casting method (die casting method).
As compared with the case of (1), since the cooling is performed in a relatively short time, the structure is refined and the crystal grain size is small. Further, since the area of the grain boundary is large and the R-rich phase is thinly spread in the grain boundary,
Also excellent in dispersibility of R-rich phase.

[0007] In addition, according to the hydrogen crushing method, the quenched alloy is
Since it is easily broken at the grain boundary, an R-rich phase tends to appear on the particle surface of the alloy powder obtained by pulverizing the quenched alloy. Since R in the R-rich phase easily reacts with oxygen,
The quenched alloy powder is very easily oxidized and is in a state of easily generating heat and igniting. In addition, it is considered that the magnetic properties are significantly deteriorated accordingly.

Next, an example of a hydrogen pulverizing process performed on a conventional ingot alloy will be described.

First, after a magnetic alloy (a collection of ingots of about 3 cm on a side) cast by a water-cooled mold is filled in a flat-pack-shaped processing vessel, the processing vessel is mounted on a rack. After inserting the rack into the hydrogen furnace, the inside of the hydrogen furnace is evacuated by evacuation. Thereafter, hydrogen gas is supplied into the hydrogen furnace, and hydrogen is occluded in the raw material. After a lapse of a predetermined time, the raw material is heated while evacuating the hydrogen furnace to release hydrogen from the raw material. After sufficient release of hydrogen from the raw material and cooling, the lid of the hydrogen furnace is opened, and the rack on which the processing vessel is mounted is taken out of the hydrogen furnace (in the atmosphere). At the end of the hydrogen grinding, the alloy has collapsed to a size of about 1 cm. Thereafter, the raw material is taken out of the processing container, and the raw material that has been subjected to the hydrogen pulverization process is subjected to
After pulverizing to a size of about 400 μm, it is finely pulverized by a jet mill or the like to an average particle size of about 2 to 5 μm.

A sintered magnet can be manufactured by preparing a breath green (press-formed body) from the fine powder of the raw material thus prepared, and then performing a sintering treatment and an aging treatment step.

[0011]

However, according to the conventional method, when the raw material is taken out of the hydrogen furnace into the atmosphere, the rare earth element R contained in the raw material after the hydrogen pulverization oxidizes upon contact with the air, There is a problem that the magnetic characteristics are eventually deteriorated.

For example, when the raw material contains neodymium as the rare earth element R, NdH ₃ is formed by storing hydrogen in the raw material, and NdH ₃ is changed to NdH ₂ by releasing hydrogen from the raw material. However, at the industrial mass production level, complete release of hydrogen cannot be realized, and NdH ₃ remains in a part of the raw material. In particular, since sufficient heat treatment is not achieved in the center of the processing vessel,
A large amount of NdH ₃ may remain in that portion. If NdH ₃ remains in the raw material, when the raw material is taken out of the processing container, NdH ₃ comes into contact with the atmosphere and generates heat.
For this reason, it is necessary to provide a cooling period after taking out the raw material, and not only there is a problem that it is not possible to immediately start a post-process such as pulverization, but also there is a risk of ignition.

When the above-mentioned hydrotreating method is applied to a quenched alloy produced by a strip casting method or the like, heat and ignition due to oxidation are particularly prone to be generated. In the conventional method, the quenched alloy is industrially pulverized. Was found to be extremely difficult. Hereinafter, this point will be described in detail.

Since the thickness of the quenched alloy is relatively thin as compared with the ingot alloy and the metal structure is fine, most of the quenched alloy is already pulverized at the time of hydrogen pulverization (the average size is 1.0 mm). Below). Therefore, the total surface area of the pulverized powder increases. Further, since the R-rich phase is finely divided and has a high dispersibility, the R-rich phase is easily exposed on the surface of the ground hydrogen powder. From the above, in the quenched alloy powder immediately after hydrogen pulverization, the unreacted active rare earth element R
Is exposed in large quantities and is in a state of being very easily oxidized. Therefore, after hydrogen pulverization, the powder is cooled to room temperature (about 20 ° C.).
Unless cooled down, there is a risk of ignition, and if a large amount of the exposed rare earth element is oxidized or nitrided, the magnetic properties of the final magnet product will be significantly deteriorated.

If hydrogen crushed powder is cooled in a furnace using a low-temperature inert gas to suppress such oxidation and nitridation reactions, dew condensation occurs in the furnace when the furnace lid is opened. However, there is also a problem that when evacuation is performed in the next lot, moisture evaporates in the furnace, and it takes a long time to reach a vacuum state. In the case of a quenched alloy, since the hydrogen pulverized powder is particularly fine, the air permeability is poor, and it has been difficult for an inert gas for cooling to sufficiently remove the heat of the pulverized powder.
Therefore, there is a problem that the time required for cooling becomes longer, and the cooling step greatly reduces productivity.

The present invention has been made in view of the above points, and its main purpose is to shorten the entire processing time and efficiently and safely perform the hydrogen pulverization processing step and the subsequent cooling step. An object of the present invention is to provide a hydrogen pulverizer capable of preventing oxidation of a raw material and improving magnetic properties while performing the same.

Another object of the present invention is to provide a method of manufacturing a rare earth magnetic material powder and a method of manufacturing a magnet which can safely and efficiently carry out pulverization even using a quenched alloy having a fine structure represented by a strip cast alloy. Is to provide.

[0018]

SUMMARY OF THE INVENTION A hydrogen crushing apparatus according to the present invention is a hydrogen crushing apparatus for performing a hydrogen crushing process on a rare-earth magnetic material, comprising a furnace body having an opening and a lid capable of closing the opening. A hydrogen furnace having a sealable structure, a take-out chamber that temporarily surrounds the rare-earth magnetic material when the rare-earth magnetic material after the hydrogen pulverization process is taken out from the opening of the furnace body, and the take-out chamber And an inert gas supply unit for supplying an inert gas into the room.

In a preferred embodiment, the opening of the furnace main body can be opened and closed by moving the lid of the hydrogen furnace in the extraction chamber.

In a preferred embodiment, the discharge chamber has a door for a discharge chamber, and the discharge chamber can form a substantially closed state when the door for the discharge chamber is closed.

In a preferred embodiment, there is provided a cooling device capable of sequentially supplying an inert gas at room temperature and a cooled inert gas into the hydrogen furnace.

A rotary cooler according to the present invention is provided with a cooling cylinder rotatably supported, cooling means for cooling the cooling cylinder, control means for controlling a rotation speed of the cooling cylinder, and provided in the cooling cylinder. And a rotation control means for controlling a rotation speed of the cooling cylinder based on an output of the temperature detection means.

A rotary cooler according to the present invention is a rotary cooler including a cooling cylinder provided with a spiral fin portion on an inner wall and rotatably supported, and a water spray device for cooling the outside of the cooling cylinder. The cooling cylinder has a raw material input section and a raw material discharge section at both ends, and the raw material input section is supported by being inclined with respect to the horizontal direction so as to be positioned above the raw material discharge section, The raw material powder in the cooling cylinder can be conveyed from the raw material input section toward the raw material discharge section according to the rotation of.

In a preferred embodiment, the cooling cylinder includes a buffer zone for storing the raw material powder supplied from the raw material charging section and a plurality of cylindrical portions, and is cooled by water discharged from the water sprinkler. And a cooling zone.

In a preferred embodiment, the apparatus further comprises means for supplying an inert gas into the cooling cylinder.

In a preferred embodiment, the raw material charging section of the cooling cylinder is connected to a room into which an inert gas is supplied, and in the room, the rare earth magnetic alloy powder after hydrogen pulverization is treated with the raw material powder. Can be supplied to the inside of the cooling cylinder via the raw material charging section.

[0027] The hydrogen crushing method according to the present invention is characterized in that a rare earth magnetic material is crushed by using any of the above hydrogen crushers.

[0028] The method for producing a rare earth magnetic material powder according to the present invention includes a hydrogen grinding treatment step of grinding the rare earth magnetic material using any of the above hydrogen grinding devices, and a step of removing the rare earth magnetic material from the hydrogen grinding device. And a removing step.

In a preferred embodiment, the method further includes a step of transporting the rare-earth magnetic material taken out of the hydrogen crusher by using a transport device having a means for supplying an inert gas therein.

In a preferred embodiment, the method includes a step of cooling the rare earth magnetic material after the hydrogen pulverizing treatment by supplying an inert gas into a hydrogen furnace of the hydrogen pulverizing apparatus.

In a preferred embodiment, when supplying the inert gas into the hydrogen furnace of the hydrogen grinding apparatus, the inert gas is circulated.

In a preferred embodiment, when supplying an inert gas into the hydrogen furnace of the hydrogen crusher, the inert gas is first cooled to a predetermined temperature by using a cooled inert gas. Then, cooling is performed using an inert gas having a temperature near room temperature.

In a preferred embodiment, the method further includes a step of removing the rare-earth magnetic material from the transfer device in a room filled with an inert gas.

In a preferred embodiment, the method further includes a step of cooling the rare earth magnetic material in a cooling device filled with an inert gas.

The method of manufacturing a magnet according to the present invention includes a hydrogen crushing step of crushing a rare earth magnetic material using any one of the above-described hydrogen crushing apparatuses, and a method of manufacturing the magnet in the extraction chamber of the hydrogen crushing apparatus supplied with an inert gas. Removing the rare-earth magnetic material from the hydrogen crushing device, and transporting the rare-earth magnetic material removed from the hydrogen crushing device using a transport device filled with an inert gas. Removing the rare earth magnetic material from the transfer device in a room filled with gas and cooling the rare earth magnetic material in a cooling device filled with an inert gas; and further pulverizing the rare earth magnetic material And a step of forming a rare earth magnetic material fine powder and a step of forming and sintering the rare earth magnetic material fine powder to form a magnet.

In a preferred embodiment, the method includes a step of cooling the rare earth magnetic material after the hydrogen crushing treatment by supplying an inert gas into a hydrogen furnace of the hydrogen crushing apparatus.

In a preferred embodiment, when supplying the inert gas into the hydrogen furnace of the hydrogen crusher, the inert gas is circulated.

In a preferred embodiment, when supplying an inert gas into the hydrogen furnace of the hydrogen crusher, the inert gas is first cooled to a predetermined temperature using a cooled inert gas. Then, cooling is performed using an inert gas having a temperature near room temperature.

The method for producing a rare earth magnetic material powder of the present invention is characterized in that R ₂ T ₁₄ having a minor axis size of 0.1 μm or more and 100 μm or less and a major axis size of 5 μm or more and 500 μm or less.
B crystal grains (R is a rare earth element, T is iron, or a transition metal element partially substituting iron and iron, and B is boron)
And R which is dispersed at the grain boundaries of the R ₂ T ₁₄ B crystal grains.
Containing rich phase and having a thickness of 0.03 mm or more and 1
The method includes a step of hydrogen embrittlement of a rare-earth magnetic alloy of 0 mm or less in a furnace, and a step of removing the alloy from the furnace in an inert atmosphere.

The method for producing a rare earth magnetic material powder according to the present invention is a rare earth magnetic alloy having a thickness of 0.03 mm or more and 10 mm or less produced by quenching a molten alloy, and comprising an R ₂ T ₁₄ B crystal. Rare earth magnetic alloys in which grains (R is a rare earth element, T is iron or a transition metal element which partially substitutes iron and iron, and B is boron) are elongated in the thickness direction by hydrogen embrittlement in a furnace. And removing the alloy from the furnace in an inert atmosphere.

After the alloy is hydrogen embrittled, the alloy is cooled in the furnace. After the alloy is taken out of the furnace, the alloy is moved into a cooling device, and the alloy is cooled. Cooling in a cooling device.

[0042] In a preferred embodiment, the method further comprises, before hydrogen embrittlement of the alloy, accommodating the alloy in a processing vessel and inserting the processing vessel into the furnace.
In the step of removing the alloy from the furnace, the processing container is removed from the furnace in the inert atmosphere, the alloy is separated from the processing container, and then the alloy is cooled in the cooling device.

Preferably, the inert atmosphere is argon or helium.

In a preferred embodiment, the method further includes a step of cooling the alloy in an inert atmosphere after removing the alloy from the furnace.

It is preferable that the cooling of the alloy is performed while stirring the alloy in the inert atmosphere.

The method for producing a rare earth magnetic material powder according to the present invention is directed to a rare earth magnetic alloy having a thickness of 0.03 mm or more and 10 mm or less produced by quenching a molten alloy, and comprising an R ₂ T ₁₄ B crystal. Rare earth magnetic alloys in which grains (R is a rare earth element, T is iron or a transition metal element which partially substitutes iron and iron, and B is boron) are elongated in the thickness direction by hydrogen embrittlement in a furnace. And removing the alloy from the furnace and cooling it while stirring in an inert atmosphere in a cooling device.

It is preferable that the cooling device has a cylindrical member that is driven to rotate, and that the rotation speed of the cylindrical member is controlled based on the output of a detecting means for detecting the temperature of the alloy.

The method of manufacturing a magnet according to the present invention comprises the steps of molding a rare earth magnetic alloy powder produced by any of the above methods for producing a rare earth magnetic material powder, and sintering the molded rare earth magnetic alloy powder. Performing the steps.

[0049]

Embodiments of the present invention will be described below with reference to the drawings.

[Hydrogen Crushing Apparatus] FIG. 1 shows a side view of an embodiment of a hydrogen crushing apparatus and a raw material transfer apparatus 26 according to the present invention, and FIG. 2 shows an upper surface thereof. The hydrogen crushing apparatus includes a hydrogen furnace 10 having a normal configuration, and a special extraction chamber 12 provided in front of an extraction port 16 of the hydrogen furnace 10. The hydrogen furnace 10 itself includes a furnace body 14.
And a lid 18 that opens and closes to take in and out the object to be processed into and out of the space inside the main body, and has almost the same configuration as a general-purpose hydrogen furnace. Furnace body 14
From the viewpoint of hydrogen embrittlement resistance, for example, S
Stainless steel such as US304L, SUS316, SUS316L is suitable, and the internal volume of the furnace is, for example, 3.0 to 3.0.
It is about 5.2 m ³ .

A plurality of pipes such as a hydrogen gas introduction pipe, an argon gas introduction pipe, and an exhaust pipe are connected to the furnace body 14. In the figure, the hydrogen gas introduction pipe and the argon gas introduction pipe are collectively described by reference numeral “22”.

As shown in FIG. 2, the gas introduction pipe 22 is connected to the cooling device 20, and the temperature of the gas introduced into the hydrogen furnace 10 can be adjusted by the cooling device 20. The exhaust pipe 24 is connected to an exhaust device (not shown) such as a roots pump and an oil rotary pump.

A heater (not shown) made of graphite or the like which is resistant to hydrogen gas is disposed as a heating device inside the furnace body 14, and power is supplied to the heater from a power supply device outside the furnace. You.

The type and pressure of the atmosphere gas inside the hydrogen furnace 10 are controlled according to a preset program by adjusting the flow rate and exhaust amount of the gas supplied into the furnace. Further, the atmosphere gas temperature inside the hydrogen furnace 10 can be controlled by operating the heating device and the cooling device 20 so as to follow the profile of the set temperature while referring to the output of the temperature detector provided inside the furnace. Such temperature control is controlled by a control device (not shown).

The argon gas supplied into the furnace through the gas introduction pipe 22 is used for cooling the raw material immediately after the heat treatment, but the pipe 2 is used so that the argon gas can be circulated.
3, the used argon is recovered and used to improve the economic efficiency. Note that another inert gas such as helium may be used instead of the argon gas.

The lid 18 of the hydrogen furnace 10 is closed at least during the hydrogen crushing process, and the furnace space during the hydrogen crushing process is maintained in a completely sealed state from the outside. When the raw material is taken in and out, the lid 18 of the hydrogen furnace 10 is moved upward by the drive mechanism, and the outlet 16 of the hydrogen furnace 10 is moved.
Is released. In FIG. 1, the state in which the cover 18 is closed is indicated by a solid line, and the state in which the cover 18 is open is indicated by a two-dot chain line A.

Since the furnace body 14 and the lid 18 are structured so that the inside of the furnace has a strength that can withstand both the pressurized state and the depressurized state, various kinds of hydrogen pulverization processing can be performed safely.

A feature of the hydrogen crushing apparatus according to the present invention is that a “removal chamber 12” is installed in front of the retrieving port 16 so as to be connected to the retrieving port 16 of the hydrogen furnace 10. In that it has a configuration that can be filled with an inert gas such as helium or helium. The take-out chamber 12 does not need to have a structure capable of realizing a completely sealed state. When the raw material after hydrogen pulverization is taken out of the furnace through the take-out port 16 of the hydrogen furnace 10, the take-out chamber 12 generates heat by contact with the atmosphere. What is necessary is just to have a structure in which the air hardly flows into the room to such an extent that the phenomenon is sufficiently suppressed. If the raw material does not come into contact with the atmosphere, only the raw material may be covered with the box-shaped member.

FIG. 8 schematically shows the structure of the take-out chamber 12. As shown in FIG. 8, the extraction chamber 12 may be configured to surround the space in front of the extraction port 16 of the hydrogen furnace 10 with, for example, a thin steel plate, and the specific structure is not particularly limited. The take-out chamber 12 in the present embodiment has a door 120 that slides substantially up and down on the front surface, and raw materials are taken in and out with the door 120 opened. Further, the take-out chamber 12 is configured to have a size and a shape such that opening and closing of the lid 18 of the hydrogen furnace 10 can be performed in the take-out chamber 12.
Its internal volume is about 5.0-6.0 m ³ .

By providing such an extraction chamber 12, when the rare-earth magnetic material after hydrogen pulverization is moved into the raw material transfer device 26, the rare-earth magnetic material in a state where the reactivity is increased by the hydrogen pulverization treatment is removed. Very little contact with the atmosphere can be achieved.

The flow rate of the inert gas to be supplied to the take-out chamber 12 may be set, for example, to 1000 to 2000 NL / min so as to supply an amount about three times the capacity of the take-out chamber in a short time. When the inert gas is supplied at such a flow rate, the amount of oxygen and water vapor existing in the extraction chamber 12 is about 3 to
Within 10 minutes, the concentration decreases to a low concentration level at which the oxidation reaction does not easily occur. The “inert atmosphere” in the present invention is
It may contain a trace amount of an active gas (oxygen or nitrogen). However, the amount of oxygen in the "inert atmosphere" is 5 mol%
And the amount of nitrogen does not exceed 20 mol%. Further, the oxygen content in the inert atmosphere is more preferably 1 mol% or less, and the nitrogen content is more preferably 4 mol% or less.

In this embodiment, as shown in FIG. 3, a plurality of raw material packs (30 mm × 15 mm × 50 mm) 32 are mounted on the rack 30, and the hydrogen pulverization process can be executed in a state of being mounted on the rack 30. It is configured as follows. The raw material pack 32 is a box-shaped container formed of a material having a high thermal conductivity such as copper, for example, and the rack 30 is made of SUS304L, SUS316, SU
It is a pedestal formed from stainless steel such as S316L.

In the hydrogen furnace 10, such a rack 30
A support member for supporting the bottom of the rack 30 is arranged. The rack 30 is placed on the support member from the raw material transport device 26 and then inserted into the back. When one raw material transfer device 26 can transfer a plurality of racks 30, it is preferable to insert a plurality of racks 30 into the hydrogen furnace 10 and perform hydrogen processing on these at the same time.

It is preferable that each raw material pack 32 is filled with the raw material so that the depth from the surface is about 10 cm. This is because the whole of the raw material is easily brought into uniform contact with the hydrogen atmosphere. If a deep bottom container is filled with a large amount of raw material, it may be difficult to perform uniform hydrogen pulverization on the raw material.

[Material Conveying Apparatus] The raw material conveying apparatus 26 shown in FIGS. 1 and 2 is an apparatus capable of automatically conveying a raw material (rare earth magnetic material) to various apparatuses. Can be moved. The raw material transporting device 26 is composed of wheels and a main body supported by the wheels, and rotates on wheels by driving means (not shown) such as a motor mounted on the main body to move on a specified course. You can move. A plurality of types of lines for guiding the transport device are drawn in advance on the floor of the factory, a predetermined line is detected by a sensor provided in the raw material transport device 26, and the transport is performed while tracking the line. Is preferred. However, the transport operation may be performed using another control method.

The raw material transport device 26 used in this embodiment
Is provided with an internal space 28 large enough to store the raw materials together with the rack 30, and the internal space 28 can be filled with an inert gas during transportation. Rack 30 loaded with raw materials
The door 29 provided in the raw material transfer device 26 is opened when the material is transferred into and out of the raw material transfer device 26, and the door 29 is open during the transfer. When the rack 30 is taken in and out, the take-out device provided in the raw material conveying device 26 is
This is performed by moving back and forth in the horizontal direction while grasping a predetermined portion of the.

The material transfer device 26 arrives in front of the predetermined removal chamber 12 of the hydrogen furnace 10 and the door 29 of the material transfer device 26
After the position of the raw material transport device 26 itself is adjusted such that the material is opposed to the door of the take-out chamber 12, the door of the take-out chamber 12 is slid almost upward and opened. At this time,
Similarly, the door 29 of the raw material transport device 26 is also slid and opened. Thereafter, the rack 30 loaded with new raw material is inserted into the hydrogen furnace 10 from the raw material transfer device 26, or conversely, the rack 30 loaded with the raw material that has been subjected to the hydrogen crushing process from the hydrogen furnace 10 is loaded into the raw material transfer device 26. It is taken out inside. During the hydrogen treatment, the raw material transport device 26 is in the take-out chamber 1
It does not need to be stopped before 2 and can be moved to perform other transport operations.

[Rotary Cooler] Next, an embodiment of a rotary cooler according to the present invention will be described with reference to FIGS. FIG. 4 shows the appearance of the rotary cooler, and FIG.
(A) shows a cross-sectional configuration at a portion indicated by an arrow B, and (b)
Indicates a cross-sectional configuration in a portion indicated by an arrow C. Also,
FIG. 6 schematically shows the internal structure of the rotary cooler 40.

The raw material that has been subjected to the hydrogen treatment is returned together with the rack 30 into the raw material transfer device 26 without directly contacting the atmosphere, and then transferred to the place where the rotary cooler 40 is installed. At this time, since the temperature of the hydrogen-crushed raw material is partially about 50 to 60 ° C., the raw material is cooled by the rotary cooler 40 for the purpose of rapidly lowering the temperature. In particular, even if the temperature of the raw material at the exposed surface portion of the raw material pack was reduced to about room temperature by cooling in the hydrogen furnace, the raw material was located inside the raw material pack when the raw material was taken out from the raw material pack and stirred. The raw material may come into contact with the atmosphere, causing an oxidation reaction and generating heat. In order to avoid such a situation, it is desirable that the whole of the raw material is sufficiently cooled by the rotary cooler 40.

The rotary cooler 40 according to the present embodiment
As shown in FIGS. 4 to 6, a cooling cylinder 42 having spiral inner walls (fins) 44a and 44b therein.
And a water spray device 46 that can spray water to the cooling cylinder 42 to cool the raw material. Cooling cylinder 42
Is rotatably supported by support mechanisms 53 and 54 and the like, and is rotated by a motor 50. The driving force of the motor 50 is transmitted to the cooling cylinder 42 via a belt 51 as shown in FIG.

The cooling cylinder 42 is connected at both ends to a raw material charging section 48 and a raw material discharging section 49, so that the raw material charging section 48 is positioned above the raw material discharging section 49 in a horizontal direction (a direction parallel to the floor surface D). (Inclination angle: 2 to 10
°). Therefore, the cooling cylinder 42 is rotated according to the rotation of the cooling cylinder 42.
The raw material powder therein can be conveyed from the raw material input section 48 to the raw material discharge section 49.

The outer diameter of the cooling cylinder 42 according to this embodiment is about 1
200 mm and its length is about 6-7 m. The cooling cylinder 42 is made of, for example, SUS3 so that rust and the like are not mixed.
It is preferably made of stainless steel such as 04.

The cooling cylinder 42 is divided into a buffer zone for storing the raw material powder supplied from the raw material charging section 48 and a cooling zone for efficiently cooling the raw material. The buffer zone has a configuration in which a spiral fin is attached to the inner wall of one large cylindrical body (inner diameter: 650 mm, for example). In contrast, the cooling zone is
As shown in FIG. 5B and FIG. 6, the water sprinkling device 4 includes a large number of small tubes 420 (inner diameter: 150 mm, for example).
6 has a structure that is easy to be cooled by the water discharged. Spiral fins 44b are also provided in the narrow tube 420 in the cooling zone. The reason why the inside of the cylindrical body is subdivided in this way is to bring as much of the raw material as possible into contact with the inner peripheral wall portion of the fine cylinder 420 and efficiently execute cooling by spraying water.

Since the raw material is stirred inside the rotary cooler 40, when it comes into contact with the air, oxidation and heat generation may occur. For this reason, in the present embodiment, the cooling process is performed in a state where the inert gas is supplied into the cooling cylinder 42. From the viewpoint of preventing oxidation and heat generation, it is preferable that the raw material charging section 48 of the cooling cylinder 42 is connected to an automatic take-out device described below.

The raw material discharge portion 49 is an opening for taking out the cooled raw material to the outside of the rotary cooler 40 (in the atmosphere), and a temperature sensor is mounted near the opening. The raw material sufficiently cooled by the rotary cooler 40 is taken out from the raw material discharge unit 49, and then is conveyed to a fine pulverizing device, where it is subjected to a fine pulverizing process.

According to the rotary cooler having the above structure, for example, the time required for cooling a 500 kg raw material is as follows:
It takes about 30 to 50 minutes. As shown in FIG. 6, the rotation speed of the cooling cylinder 42 is, for example, 2 to 8 rpm depending on the output of the temperature sensor 60 provided near the discharge unit 49. p. It is controlled to an optimum value in the range of m. The output of the temperature sensor 60 is transmitted to the control circuit 62, and when the temperature of the raw material is high, the rotation speed of the motor 50 is reduced by the motor controller 64, thereby achieving sufficient cooling. As a result, the raw material is reliably cooled below a certain level of temperature.

[Automatic take-out device] The automatic take-out device is a device that takes out the raw material subjected to the hydrogen pulverizing process from the raw material transfer device 26 and supplies it to the raw material input port 48 of the rotary cooler 40. At the stage of such removal, the inside of the raw material packed in the raw material pack 32 may be in a relatively high temperature and active state. May occur. However, if the raw material is sufficiently cooled inside the hydrogen furnace 10, the possibility of heat generation at the time of removal is reduced, but the use time of the hydrogen furnace 10 is increased, so that the throughput is reduced. Therefore, in the present embodiment, the operation of extracting the raw material from the raw material pack 32 is performed in an inert atmosphere.

FIG. 9 shows an embodiment of the automatic take-out device. The apparatus uses a first belt 91 on which the rack 30 is placed and carried, and a second belt 92 on which the pack 32 emptied by taking out the raw material is placed and carried out of the apparatus.

A pusher (not shown) for pushing the pack 32 forward (toward the front of the figure) is provided at the rear of the rack 30 in the figure, and the plurality of packs 32 mounted on the rack 32 are sequentially pushed by the pusher. It is pushed forward (frontward in the figure). The extruded pack 32 is gripped by the robot arm 90 that rotates about the support shaft, and is conveyed above the input port 48 of the rotary cooler with the rotation of the support shaft, where it rotates upside down. Is done. Thus, the raw material in the pack 32 is put into the rotary cooler and undergoes a cooling process. The operation of the robot arm 90 is performed according to a preset program.

The automatic take-out apparatus according to the present embodiment includes a housing partitioned from the outside so as to form a substantially closed space. The housing receives the raw material pulverized with hydrogen together with the rack 30. The opening (not shown) is provided, and this opening is opened and closed by a door. A conduit for supplying an inert gas is connected to the apparatus.
r) in an inert atmosphere. Therefore, oxidation of the rare earth magnetic material as a raw material is suppressed.

When the hydrogen pulverized raw material is moved from the raw material pack 32 to the rotary cooler 40, the raw material pack 32
The raw material located inside or at the bottom of the substrate comes into contact with the atmospheric gas, but since the atmospheric gas is an inert gas, no oxidation reaction occurs.

[Method of Manufacturing Magnet] An embodiment of a method of manufacturing a magnet according to the present invention will be described below.

First, a raw material alloy of an RT- (M) -B based magnet alloy having a desired composition is prepared by a known strip casting method and stored in a predetermined container. When manufactured by the strip casting method, the thickness of this raw material alloy is in the range of 0.03 mm or more and 10 mm or less. This strip cast alloy has a short axis direction size of 0.1 μm or more and 100 μm or less and a long axis direction size of 5 μm or more and 500 μm or less.
μm and below R ₂ T ₁₄ B crystal grains, containing the R-rich phase which is present dispersed in the grain boundary of the R ₂ T ₁₄ B crystal grains. The thickness of the R-rich phase is 10 μm or less. It is preferable that the raw material alloy is roughly pulverized into flakes having an average particle size of 1 to 10 mm before the hydrogen treatment. A method for producing a raw material alloy by a strip casting method is described in, for example, US Pat.
383,978.

Next, a plurality of raw material packs 32 are filled with the coarsely pulverized raw material alloy and mounted on a rack 30. After this,
The rack 30 on which the raw material pack 32 is mounted is transported to the front of the hydrogen furnace 10 using the raw material transport device 26 described above, and inserted into the hydrogen furnace 10. At this time, take out chamber 12
Further, it is not necessary to fill the inside of the raw material transfer device 26 with an inert gas.

Next, the lid 18 of the hydrogen furnace 10 is closed, and the hydrogen crushing process is started. The hydrogen pulverization process is performed according to, for example, a temperature profile as shown in FIG. In the example of FIG. 7, after first performing the evacuation process I for 0.5 hour,
Perform hydrogen storage process II for 2.5 hours. Hydrogen storage process II
Then, hydrogen gas is supplied into the furnace, and the inside of the furnace is set to a hydrogen atmosphere. At that time, the hydrogen pressure is preferably about 200 to 400 kPa.

Subsequently, after performing the dehydrogenation process III under a reduced pressure of about 0 to 3 Pa for 5.0 hours, the raw material cooling process IV is performed for 5.0 hours while supplying argon gas into the furnace.

In the cooling process IV, when the atmosphere temperature in the furnace is relatively high (for example, when the temperature exceeds 100 ° C.), an inert gas at room temperature is supplied into the hydrogen furnace 10 to cool it. Thereafter, at the stage when the raw material temperature is lowered to a relatively low level (for example, when the temperature is 100 ° C. or lower), an inert gas cooled to a temperature lower than normal temperature (for example, room temperature minus about 10 ° C.) is supplied into the hydrogen furnace 10. Is preferable from the viewpoint of cooling efficiency. The supply amount of argon gas is 10 ~
It may be about 100 Nm ³ / min.

When the temperature of the raw material is lowered to about 20 to 25 ° C., the temperature is substantially equal to the normal temperature (lower than room temperature, but the difference from room temperature
It is preferable to blow an inert gas (at a temperature in the range of not more than ° C.) into the hydrogen furnace 10 and wait until the temperature of the raw material reaches the normal temperature level. By doing so, when the lid 18 of the hydrogen furnace 10 is opened, a situation in which dew condensation occurs inside the furnace can be avoided. If moisture is present inside the furnace due to dew condensation, the moisture will freeze and evaporate in the evacuation step, making it difficult to increase the degree of vacuum and increasing the time required for the evacuation step I.

The take-out step is performed in the following procedure.

First, the raw material transfer device 26 is substantially connected to the extraction chamber 12 of the hydrogen furnace 10. Then, the inside of both the raw material transfer device 26 and the take-out chamber 12 is filled with an inert gas. If a large gap is inevitably formed between the raw material transport device 26 and the take-out chamber 12, the space of the gap may be covered with a bellows-like enclosure. Such a bellows-shaped enclosure can be
6 or the take-out chamber 12 may be attached in a stretchable manner.

When the inert gas has been sufficiently supplied to the inside of the raw material transfer device 26 and the take-out chamber 12, the lid 18 of the hydrogen furnace 10 is opened. Then, the arm of the raw material transfer device is extended into the hydrogen furnace 10, and the raw material pack 32 filled with the raw material is taken out together with the rack 30 to the outside.
By doing so, the raw material after hydrogen pulverization does not come into contact with the atmosphere, so that the raw material is prevented from oxidizing and generating heat, and the magnetic properties of the magnet can be greatly improved.

When the lid 18 of the hydrogen furnace 10 is opened,
Argon gas is discharged from the furnace into the extraction chamber 12. For this reason, when the volume of the hydrogen furnace 10 is sufficiently large compared to the volume of the extraction chamber 12, the hydrogen furnace 10 does not need to be supplied to the extraction chamber 12 in advance.
By opening the lid 18, a sufficient amount of inert gas for preventing oxidation can be supplied from the hydrogen furnace 10 to the removal chamber 12. In such a case, it can be said that the hydrogen furnace 10 itself functions as an inert gas supply unit.

Next, the raw material transfer device 26 is transferred to a position before the automatic removal device for the rotary cooler. The raw material is supplied from the raw material pack 32 on the rack 30 to the raw material inlet of the rotary cooler 40 by the automatic take-out device. Raw materials are
While moving inside the rotary cooler 40, it is cooled by water spray and discharged from the raw material discharge port. At this time, since the raw material is stirred by the rotary cooler, the embrittled raw material is pulverized more finely. Thus, in the case of the strip cast alloy, the raw material discharged from the discharge port can be directly pulverized by the jet mill.

Here, an example in which the raw material is taken out after the temperature of the raw material is lowered to about room temperature in the hydrogen furnace 10 has been described, but the raw material is taken out.
Even if the raw material is taken out as it is (° C.), particularly serious oxidation does not occur because the raw material does not come into contact with the atmosphere. When the raw material is taken out in such a high temperature state, the time of the cooling process by the rotary cooler 40 may be relatively long. According to the rotary cooler 40 having the above-described configuration, in order to realize an efficient cooling process, a relatively high-temperature raw material is taken out without taking much time for cooling in the hydrogen furnace 10, and the main cooling process is performed by the rotary cooler. It can be said that execution at 40 is preferable from the viewpoint of improving production efficiency.

The raw material powder cooled to about room temperature is further subjected to a pulverizing process using a pulverizing device such as a jet mill to produce a fine powder of the raw material. After mixing the lubricant with the fine powder, the powder is formed into a desired shape using a press forming apparatus, whereby a press-formed body is produced.
The press-formed body undergoes a series of processes such as a delubrication process, a sintering process, a cooling process, and an aging process, and the manufacturing process of the rare earth alloy sintered magnet is completed.

According to the above embodiment, not only the production efficiency is improved, but also the oxidation of the raw material is prevented, so that the magnetic characteristics are improved. Table 1 below shows examples of improvement in magnetic characteristics.

[0097]

[Table 1]

Here, _Br is the residual magnetic flux density, H _cb and H _cj are the coercive force, (BH) _max is the maximum energy product, and O ₂ is the oxygen concentration in the magnet after sintering. The unit of B _r is [T], H _cb, and the unit of H _cj is [kA / m], (B
H) The unit of _max is [kJ / m ³ ] and the unit of O ₂ is [pp
m]. From this table, it can be seen that the amount of oxygen in the magnet according to the present invention is reduced and the coercive force is improved.

The present invention is not limited to the pulverization of rare earth magnet materials with hydrogen, but can exhibit a sufficient effect (for example, an effect of preventing dew condensation) even when applied to hydrogen treatment of other magnet materials. Can be.

Although the present invention has been described with reference to a strip cast alloy, the scope of the present invention is not limited to this. For example, the present invention is suitably applied to the pulverization of an alloy rapidly solidified by a centrifugal casting method as described in JP-A-9-31609.

In the above embodiment, the present invention has been described with respect to a batch-type furnace. However, the present invention uses a continuous furnace in which a hydrogen treatment chamber, a heating chamber, a cooling chamber, and the like are arranged in series. May be implemented.

[0102]

According to the present invention, it is possible to avoid a situation in which the raw material comes into contact with the atmosphere immediately after the hydrogen pulverization, so that deterioration of the raw material due to oxidation can be prevented, and magnetic powder excellent in magnetic properties can be mass-produced. It becomes possible. In addition, since the cooling time in the hydrogen furnace can be reduced, the throughput is improved. Further, since entry of the atmosphere into the hydrogen furnace is suppressed, dew condensation in the hydrogen furnace can be prevented, the time required for depressurization in the furnace is reduced, and production efficiency is improved.

The present invention is particularly suitable for the pulverization of a rapidly solidified alloy in which the alloy structure is refined and a large amount of rare earth elements are likely to be exposed on the surface of the powder particles.

[Brief description of the drawings]

FIG. 1 is a side view showing an embodiment of a hydrogen grinding apparatus and a raw material transport apparatus according to the present invention.

FIG. 2 is a top view showing one embodiment of a hydrogen crushing apparatus and a raw material transport apparatus according to the present invention.

FIG. 3 is a diagram showing a rack on which a plurality of raw material packs are mounted.

FIG. 4 is a side view showing the appearance of the embodiment of the rotary cooler according to the present invention.

FIGS. 5A and 5B are cross-sectional views showing an embodiment of a rotary cooler according to the present invention.

FIG. 6 is a diagram schematically showing an internal structure of an embodiment of a rotary cooler according to the present invention.

FIG. 7 is a graph showing an example of a temperature profile of a hydrogen grinding process.

FIG. 8 is a schematic diagram showing one configuration example of a take-out chamber provided in the hydrogen crusher of the present invention.

FIG. 9 is a schematic diagram showing one configuration example of the automatic unloading device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Hydrogen furnace 12 Take-out chamber 14 Furnace main body 16 Hydrogen furnace take-out port 18 Lid 20 Cooling device 24 Exhaust pipe 26 Raw material transport device 29 Raw material transport device door 30 Rack 32 Raw material pack 40 Rotary cooler 42 Cooling cylinder 44a Spiral inner wall (Fin) 44b Spiral inner wall (fin) 46 Watering device 48 Raw material input unit 49 Raw material discharge unit 50 Motor 51 Belt 55 Support mechanism 54 Support mechanism 420 Thin tube in cooling zone

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Katsumi Okayama 2-15-17 Egawa, Shimamoto-cho, Mishima-gun, Osaka Prefecture F-term in Sumitomo Special Metals Co., Ltd. Yamazaki Works 4K017 AA04 BA03 BA06 BB12 DA02 EA03 EA08 EK07 5E040 AA03 AA04 CA01 HB11 HB17 HB19 NN01 NN06 NN17

Claims (28)

[Claims] 1. A hydrogen crushing apparatus for performing a hydrogen crushing process on a rare earth magnetic material, comprising: a furnace body having an opening; and a lid capable of closing the opening, and a hydrogen furnace having a sealable structure. An extraction chamber that temporarily surrounds the rare-earth magnetic material when extracting the rare-earth magnetic material after the hydrogen pulverization process from the opening of the furnace body; and an inert gas for supplying an inert gas into the extraction chamber. A hydrogen pulverizer, comprising: gas supply means. 2. The hydrogen crushing apparatus according to claim 1, wherein the lid of the hydrogen furnace opens and closes an opening of the furnace body by moving in the extraction chamber. 3. The discharge chamber has a door for a discharge chamber, and the discharge chamber can form a substantially sealed state when the door for the discharge chamber is closed. Hydrogen crushing apparatus according to item 1. 4. The cooling apparatus according to claim 1, further comprising a cooling device capable of sequentially supplying a normal temperature inert gas and a cooled inert gas into the hydrogen furnace. Hydrogen crusher. 5. A cooling cylinder rotatably supported; cooling means for cooling the cooling cylinder; control means for controlling a rotation speed of the cooling cylinder; and temperature detecting means provided on the cooling cylinder. A rotary cooler, wherein the rotation control means controls a rotation speed of the cooling cylinder based on an output of the temperature detection means. 6. A hydrogen pulverizing treatment method for pulverizing a rare earth magnetic material using the hydrogen pulverizing apparatus according to claim 1. Description: 7. A hydrogen crushing process step of crushing a rare earth magnetic material using the hydrogen crushing device according to claim 1, and an extraction chamber of the hydrogen crushing device supplied with an inert gas. Removing the rare-earth magnetic material from the hydrogen crusher. 8. The method according to claim 7, further comprising a step of receiving and transporting the rare-earth magnetic material taken out of the hydrogen crusher, using a transport device having a means for supplying an inert gas therein. A method for producing a rare earth magnetic material powder. 9. The method according to claim 7, further comprising a step of supplying an inert gas into a hydrogen furnace of the hydrogen grinding apparatus to cool the rare earth magnetic material after the hydrogen grinding processing. A method for producing the rare earth magnetic material powder described above. 10. The method for producing a rare earth magnetic material powder according to claim 9, wherein the inert gas is circulated when supplying the inert gas into the hydrogen furnace of the hydrogen grinding apparatus. 11. When supplying an inert gas into the hydrogen furnace of the hydrogen crusher, the inert gas is first cooled to a predetermined temperature using a cooled inert gas, and then cooled to room temperature. The method for producing a rare earth magnetic material powder according to claim 10, wherein the cooling is performed using an inert gas having a temperature in the vicinity. 12. The method for producing a rare earth magnetic material powder according to claim 7, further comprising a step of taking out the rare earth magnetic material from the transfer device in a room filled with an inert gas. Method. 13. The method of producing a rare earth magnetic material powder according to claim 7, further comprising a step of cooling the rare earth magnetic material in a cooling device filled with an inert gas. 14. A hydrogen crushing treatment step of crushing a rare-earth magnetic material using the hydrogen crushing apparatus according to claim 1, and a take-out chamber of the hydrogen crushing apparatus supplied with an inert gas. Removing the rare earth-based magnetic material from the hydrogen crusher; and transporting the rare earth-based magnetic material removed from the hydrogen crusher using a carrier filled with an inert gas. Removing the rare-earth magnetic material from the transfer device in a room filled with an active gas, and cooling the rare-earth magnetic material in a cooling device filled with an inert gas; Pulverizing to produce fine powder of rare earth magnetic material; and forming the fine powder of rare earth magnetic material and sintering to produce a magnet. Production method. 15. The method according to claim 14, further comprising a step of cooling the rare-earth magnetic material after the hydrogen pulverization by supplying an inert gas into a hydrogen furnace of the hydrogen pulverizer. Manufacturing method of magnet. 16. The method according to claim 15, wherein the inert gas is circulated when supplying the inert gas into the hydrogen furnace of the hydrogen crusher. 17. When supplying an inert gas into the hydrogen furnace of the hydrogen crusher, the inert gas is first cooled to a predetermined temperature using a cooled inert gas, and then cooled to a room temperature. 17. The method according to claim 15, wherein cooling is performed using an inert gas having a temperature in the vicinity. 18. The minor axis size is 0.1 μm or more and 10 or more.
R ₂ T ₁₄ B crystal grains having a major axis direction size of 5 μm or more and 500 μm or less (R is a rare earth element, T is iron, or a transition metal element partially substituting iron and iron, and B is boron) And an R-rich phase dispersed and present at the grain boundaries of the R ₂ T ₁₄ B crystal grains, and having a thickness of 0.03
A method for producing a rare earth magnetic material powder, comprising: a step of hydrogen embrittlement of a rare earth magnetic alloy having a size of not less than 10 mm and not more than 10 mm in a furnace; and a step of removing the alloy from the furnace in an inert atmosphere. 19. A rare earth magnetic alloy having a thickness of 0.03 mm or more and 10 mm or less produced by quenching a molten alloy, wherein R ₂ T ₁₄ B crystal grains (R is a rare earth element, T is iron, A step of hydrogen embrittlement in a furnace of a rare earth magnetic alloy in which iron and a transition metal element in which a part of iron is substituted, and B is boron) in a thickness direction, and the alloy in an inert atmosphere. Removing the rare earth-based magnetic material powder from the furnace. 20. A step of cooling the alloy in the furnace after hydrogen embrittlement of the alloy, and after removing the alloy from the furnace, moving the alloy into a cooling device, The method for producing a rare earth magnetic material powder according to claim 18 or 19, further comprising a step of cooling the powder in the cooling device. 21. The method further comprising, before hydrogen embrittlement of the alloy, accommodating the alloy in a processing vessel and inserting the processing vessel into the furnace. The rare earth-based system according to claim 20, wherein in the removing step, the processing container is removed from the furnace in the inert atmosphere, and after separating the alloy from the processing container, the alloy is cooled in the cooling device. Manufacturing method of magnetic material powder. 22. The method for producing a rare earth magnetic material powder according to claim 18, wherein the inert atmosphere is argon or helium. 23. The method for producing a rare earth magnetic material powder according to claim 18, further comprising a step of cooling the alloy in an inert atmosphere after removing the alloy from the furnace. 24. The method for producing a rare earth magnetic material powder according to claim 23, wherein the cooling of the alloy is performed while stirring the alloy in the inert atmosphere. 25. The method according to claim 20, wherein the cooling of the alloy is performed while stirring the alloy in the inert atmosphere. 26. A rare earth magnetic alloy having a thickness of not less than 0.03 mm and not more than 10 mm produced by rapidly cooling a molten alloy, wherein R ₂ T ₁₄ B crystal grains (R is a rare earth element, T is iron, Or a transition metal element in which iron and a part of iron are substituted, and B is boron) hydrogen embrittlement in the furnace of a rare earth magnetic alloy extending in the thickness direction, and the alloy is removed from the furnace. And cooling the sample in a cooling device while stirring in an inert atmosphere in a cooling device. 27. The cooling device has a cylindrical member that is driven to rotate, and controls a rotation speed of the cylindrical member based on an output of a detecting unit that detects a temperature of the alloy. 3. The method for producing a rare earth magnetic material powder according to item 1. 28. A step of molding the rare earth magnetic alloy powder obtained by the method for producing a rare earth magnetic material powder according to any one of claims 18 to 27; And a sintering step.