JP2672035B2 - Method and apparatus for producing metal powder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for producing a metal powder by supplying a molten metal into a swirling cooling liquid layer.

[0002]

2. Description of the Related Art A rapidly solidified metal powder has a fine crystal grain and can contain an alloy element in a supersaturated state. For example, an extruded material formed by a rapidly solidified powder of aluminum or an alloy thereof is provided as a molten material. It has excellent material properties without any problems and has attracted attention as a material for machine parts and the like.

[0003] As a preferred method of producing the rapidly solidified metal powder, there is a rotary drum method. In this method, as shown in FIG. 3, a cooling liquid layer 62 is formed on the inner peripheral surface of a rotating cooling drum 61 by the action of centrifugal force, and molten metal is sprayed on the cooling liquid layer 62 to be finely divided. This is a method of obtaining a rapidly solidified metal powder. In the figure, 63 is an injection crucible as a molten metal supply container, the outer peripheral surface of which is a high-frequency coil for heating.
64 is mounted, and a nozzle hole 65 is opened in the lower side wall thereof. The molten metal 66 in the crucible 63 is injected and supplied from the nozzle hole 65 by injecting an inert gas 67 into the crucible 63 under pressure. Then, when a certain amount of the metal powder in the cooling drum 61 accumulates, the rotation of the cooling drum 61 is stopped, the metal powder is collected together with the cooling liquid, drained, and dried. A method for producing such metal powder is disclosed in Japanese Patent Publication No. 1-49769.

[0004]

However, the rotary drum method is a so-called batch operation, and the productivity is poor. In addition, since the injection of the molten metal must be stopped when collecting the powder, there is a problem that the nozzle is likely to be clogged. Further, in order to keep the cooling temperature constant, it is necessary to supply and discharge the cooling liquid from the liquid surface of the cooling liquid layer to control the temperature, but at this time, the liquid surface is disturbed and the powder particle size and quality vary. There is a problem that it easily occurs.

Further, after the molten metal is injected, the surface thereof is oxidized by the time it reaches the cooling liquid layer, and an oxide film is formed, so that it is difficult to divide the cooling liquid layer, and oxygen and hydrogen of the metal powder are also formed. The content increases, which causes quality deterioration. It is an object of the present invention to provide a metal powder production method and apparatus capable of continuously producing metal powder of stable quality and suppressing generation of an oxide film.

[0006]

A method for producing metal powder according to the present invention is a method for producing metal powder by supplying molten metal from a nozzle hole of a molten metal supply container to a cooling liquid layer in a cooling cylinder. To form a cooling liquid layer flowing down while swirling along the inner peripheral surface of the cooling cylinder, and to make the molten metal supply path from the nozzle hole to the cooling liquid layer an inert gas atmosphere, The molten metal is supplied to the cooling liquid layer while supplying an inert gas from the surroundings along the above path, and the molten metal is divided by the cooling liquid layer to be cooled and solidified to obtain a metal powder. .

At the time of supplying the molten metal, a pressure medium such as an inert gas may be supplied to the molten metal supply container to inject the molten metal in the container through a nozzle hole, or the self-weight of the molten metal in the container. May be supplied by jetting from the nozzle hole. An apparatus for suitably carrying out the above method comprises a molten metal supply container and a cooling powder cylinder in which a cooling liquid layer into which a molten metal is supplied through a nozzle hole of the container is formed. In the apparatus, cooling liquid supply means for forming a cooling liquid layer flowing down while swirling along the inner peripheral surface of the cooling cylinder is provided in the cooling cylinder, while molten metal from the nozzle hole to the cooling liquid layer is provided. An inert gas atmosphere forming means for supplying an inert gas from the periphery of the nozzle hole along the supply path to make the path an inert gas atmosphere can be provided.

As the above-mentioned inert gas atmosphere forming means, a conduit extending from the vicinity of the nozzle hole toward the cooling liquid layer so as to surround the molten metal supply path from the nozzle hole, and an inert gas in the conduit. It is possible to configure by providing a gas supply means for supplying from the nozzle hole side, or
It is possible to provide a gas nozzle that injects an inert gas in the direction from the periphery of the nozzle hole toward the cooling liquid layer to form an inert gas flow surrounding the molten metal supply path from the nozzle hole.

[0009]

The cooling liquid supplied along the inner peripheral surface of the cooling cylinder flows down while swirling along the inner peripheral surface of the cylindrical body, and a centrifugal force at the time of swirling causes a cooling liquid layer having a substantially constant inner diameter to be formed. Form. When the molten metal is supplied from the inside of this cooling liquid layer, the molten metal flow or droplets are divided by the swirling flow and are cooled and solidified to become powder.

At this time, since the cooling liquid layer is always formed by the newly supplied cooling liquid, a constant temperature is easily maintained. Therefore, it is not necessary to discharge and supply the cooling liquid from the liquid surface for temperature control, and the liquid surface is not disturbed and a stable state is maintained. Therefore, the molten metal supplied to the cooling liquid layer is constantly poured and divided into the cooling liquid layer under a constant state and cooled and solidified at a constant temperature, so that the quality of the metal powder is stabilized.

The metal powder in the cooling liquid layer flows down while swirling together with the cooling liquid and is discharged from the lower end of the cylindrical body, so that the metal powder can be continuously produced. Further, the path from the nozzle hole of the molten metal supply container to the cooling liquid layer is an inert gas atmosphere due to the supply of the inert gas from the periphery of the nozzle hole, so that the molten metal reaches the cooling liquid layer. During this period, the surface oxidation of the molten metal is suppressed, the cooling liquid layer rapidly separates, and a high-quality powder having a thin oxide film is obtained.

[0012]

FIG. 1 shows a metal powder manufacturing apparatus according to an embodiment of the present invention, in which a cooling cylinder 1 having a cooling liquid layer 21 formed on its inner peripheral surface and a molten metal in the cooling liquid layer 21. An injection crucible 2 for injecting and supplying 22 and a pump 3 for supplying a cooling liquid to the cylindrical body 1 are provided.

The cylindrical body 1 has a cylindrical shape, and a lid 5 having an opening 4 for supplying the molten metal to the cooling liquid layer 21 formed at the center is attached to the upper end of the cylindrical body 1. A ring thickness adjusting ring 6 for the cooling liquid layer 21 is attached to the inner surface of the lower portion by bolts so as to be detachable and replaceable. In the upper part, a plurality of discharge ports 8 of a cooling liquid jetting pipe 7 serving as a cooling liquid supply means are opened at a plurality of positions at equal intervals from the tangential direction on the peripheral surface of the cylinder, and the pipe axis direction of the jetting pipe 7 is the cylinder axis. It is set obliquely downward about 0 to 20 degrees with respect to the plane orthogonal to the heart. At the lower end of the cylindrical body 1, a cylindrical net body 9 is continuously provided as a draining member, and at the lower end of the net body 9, a funnel body 10 for powder recovery is attached. A cover 11 is provided around the. The layer thickness adjusting ring 6 has a rectangular cross section in the illustrated example, but may be formed as a streamlined curved surface whose diameter gradually decreases from the outer peripheral edge of the upper surface of the ring to the inner peripheral edge of the lower surface.

The cooling liquid jet pipe 7 is connected to the tank 12 through the pump 3 by piping. The bottom of the cover 11 is piped to a tank 12, and the coolant recovered by the cover 11 is returned to the tank 12 and used for circulation.
The tank 12 is provided with a replenishing coolant supply pipe (not shown), and a cooler may be appropriately provided in the tank or in the circulation channel. Water is generally used as the cooling liquid, but oil may be used in some cases. When water is used, it is desirable to use water from which oxygen has been removed. Oxygen removal devices are commercially available and are easily available.

An injection crucible 2 serving as a molten metal supply container is provided on the upper portion of the lid 5 so as to be inclined with respect to the vertical direction, and a heating induction coil 14 is wound around the outer periphery thereof. A nozzle hole 15 is opened at the bottom thereof. The injection crucible 2 is made of a refractory material such as graphite or silicon nitride, and a cover 16 is attached to cover the coil 14, and its lower surface is in the vicinity of the cooling liquid layer 21 along the injection direction of the nozzle holes 15. A conduit 17 extends to the top of the cover 16
A supply pipe 18 for supplying an inert gas such as N ₂ or the like into the cover 16 is provided. In this embodiment, the gas supply means is constituted by the supply pipe 18 and the cover 16, and the nozzle hole 15 is constituted by the gas supply means and the conduit 17.
An inert gas atmosphere forming means is provided in which the supply path of the molten metal injected from the nozzle to the cooling liquid layer 21 is made an inert gas atmosphere.

On the other hand, the upper lid 19 of the injection crucible 2 is provided with an injection hole 20 for injecting a pressure medium of an inert gas such as Ar or N ₂ or a molten metal pumped. In order to manufacture the metal powder with the apparatus having the above-described structure, first, the pump 3 is operated to form the cooling liquid layer 21 that flows down on the inner peripheral surface of the cylindrical body 1 while swirling at high speed. That is, the cooling liquid ejected from the cooling liquid ejection pipe 7 along the inner peripheral surface of the cylindrical body 1 flows down while swirling along the inner peripheral surface of the cylindrical body 1 and overflows the layer thickness adjusting ring 6. Flows downwards. At this time, the flow rate of the cooling liquid is suppressed and the cooling liquid layer 21 having a substantially constant inner diameter is easily formed above the ring 6 by the action of the centrifugal force at the time of turning.

Since the cooling liquid layer 21 is always formed by a newly supplied cooling liquid, a constant temperature is easily maintained. Therefore, there is no need to supply and discharge the cooling liquid from the liquid surface for temperature control, and the liquid surface is less likely to be disturbed and excellent in stability. Next, the inert gas is supplied into the cover 16 of the injection crucible 2, the gas is discharged from the conduit 17, and the pressure medium and the molten metal are pumped into the injection crucible 2 to remove the molten metal 22 in the crucible 2. Spray from the nozzle hole 15. The injected molten metal flow or droplets are supplied to the cooling liquid layer 21 in a state of being surrounded by an inert gas in the conduit 17, divided by a swirling flow, rapidly cooled and solidified, and metal powder is continuously produced. To be done. Until the injected molten metal is injected into the cooling liquid layer 21, this powder is surrounded by an inert gas to prevent oxidation, and is pulverized by the cooling liquid layer whose temperature and liquid surface state are stable. Therefore, the oxide film is thin and the quality is stable.
The outer peripheral surface of the injection crucible 2 and the heating induction coil 14
Is covered with the inert gas injected into the cover 16, so that the oxidation is prevented and the durability is improved.

The metal powder in the cooling liquid layer 21 flows down over the layer thickness adjusting ring 6 while swirling together with the cooling liquid, and enters the draining net 9 from the lower end of the cylinder 1. Here, the cooling liquid is radially scattered and discharged from the net body 9 by the action of the centrifugal force, and a metal powder having a small amount of liquid temporarily removed is obtained. The metal powder discharged from the funnel body 10 after being primarily deliquored by the mesh body 9 has a small amount of liquid. Therefore, by sequentially applying the metal powder to an appropriate deliquoring device such as a centrifuge, the liquid is almost completely eliminated in a short time. , Easily dried to product powder.

In the above embodiment, the cylindrical body is shown as the cooling cylinder, but the invention is not limited to this. For example, a funnel shape or an inverted truncated cone with the inner peripheral surface expanding upward and formed by a paraboloid of revolution. It may have a shape. In this case, a cooling liquid layer having a constant inner diameter can be formed without attaching a layer thickness adjusting ring. Further, in the above embodiment, the molten metal in the injection crucible 2 is
The nozzle hole 15 is formed by applying a pressure medium to apply pressure.
Although it was injected from the molten metal without applying pressure medium,
22 The molten metal in the lower part of the crucible 2 is pressurized by the gravity (self-weight) acting on itself, and is injected from the nozzle hole 15.
(Spout) May be used. In this case, the axis of the cylinder 1 is inclined with respect to the vertical direction, the axis of the injection crucible 2 is changed to the vertical direction, and the molten metal that falls by gravity is supplied to the cooling liquid layer formed on the peripheral surface of the cylinder. Good.

Further, in order to surround the molten metal sprayed from the nozzle hole 15 of the spray crucible 2 with the inert gas, as shown in FIG. A slit nozzle (gas nozzle) 31 that injects an active gas and forms an inert gas flow surrounding the supply path of the molten metal from the nozzle hole 15 may be opened.
Reference numeral 32 denotes an annular air-holding chamber, which communicates with the inert gas supply hole 33.

It is needless to say that the present invention is applicable not only to the production of lightweight metal powders such as Al alloys and Mg alloys but also to the production of metal powders such as iron and its alloys.

[0022]

As described above, according to the present invention, the cooling liquid is jetted and supplied along the inner peripheral surface of the cylindrical body to form the cooling liquid layer flowing down while swirling along the peripheral surface of the cylindrical body. Therefore, the inner peripheral surface of the cooling liquid layer to which the molten metal is supplied is stable,
The temperature is also kept uniform. Then, since the molten metal is supplied into the cooling liquid layer, the rapidly solidified powder having stable quality is continuously produced, and the clogging of the injection nozzle is not caused.

Further, since the molten metal is supplied to the cooling liquid layer through an inert gas atmosphere formed by supplying an inert gas from around the nozzle hole, the molten metal is melted before reaching the cooling liquid layer. The surface oxidation of the metal is suppressed, the powder is rapidly pulverized, and a high-quality metal powder having a low oxygen or hydrogen content can be obtained.

[Brief description of the drawings]

FIG. 1 is an overall layout view of essential parts of a metal powder manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view of an injection crucible having a slit nozzle for injecting an inert gas.

FIG. 3 is a cross-sectional view of essential parts of a conventional metal powder manufacturing apparatus.

[Explanation of symbols]

1 Cooling Cylinder 2 Injection Crucible (Molten Metal Supply Container) 7 Cooling Liquid Injection Pipe (Cooling Liquid Supply Means) 15 Nozzle Hole 16 Cover (Gas Supply Means, Inert Gas Atmosphere Forming Means) 17 Conduit (Inert Gas Atmosphere Formation) Means) 18 supply pipe (gas supply means, inert gas atmosphere forming means) 21 cooling liquid layer 22 molten metal 31 slit nozzle (gas nozzle)

Continuation of the front page (56) References JP-A-61-41707 (JP, A) JP-A-62-156205 (JP, A) Actual Kaihei 2-94224 (JP, U)

Claims (5)

(57) [Claims] 1. A nozzle for cooling a molten metal supply container for cooling
Manufacturing metal powder by supplying molten metal to the cooling liquid layer in the cylinder
The method is to form a cooling liquid layer that flows down while swirling along the inner peripheral surface of the cooling cylinder, and to melt the cooling liquid layer from the nozzle holes to the cooling liquid layer.
Nozzle holes to make the molten metal supply path an inert gas atmosphere
While supplying the inert gas from around the
A method for producing a metal powder, comprising: supplying a molten metal to a cooling liquid layer; dividing the molten metal by the cooling liquid layer; 2. The method for producing metal powder according to claim 1, wherein the molten metal contained in the molten metal supply container is sprayed by its own weight through a nozzle hole formed in the lower portion of the container. 3. A molten metal supply container and a nozzle for this container.
A cooling liquid layer is formed inside which molten metal is supplied through the holes
Is a metal powder manufacturing apparatus equipped with a cooling cylinder.
Cooling that flows down while swirling along the inner peripheral surface of the cooling cylinder
A cooling liquid supply means for forming a liquid layer is installed on the cooling cylinder.
Meanwhile, along the molten metal supply path from the nozzle hole to the cooling liquid layer
Inert gas is supplied from around the nozzle hole to prevent
Inert gas atmosphere forming means for creating an active gas atmosphere
An apparatus for producing metal powder, comprising: 4. Surrounding a molten metal supply path from a nozzle hole
That extends from near the nozzle hole toward the coolant layer
And supply an inert gas into this conduit from the nozzle hole side.
Gas supply means provided as an inert gas atmosphere forming means
The device for producing metal powder according to claim 3, wherein
Place. 5. A direction from the periphery of the nozzle hole toward the cooling liquid layer.
Injecting inert gas in the opposite direction to supply molten metal from the nozzle hole
Inert gas nozzles forming an inert gas stream that surrounds the path
It is provided as a gas atmosphere forming means,
The metal powder manufacturing apparatus according to claim 3.