JPH04337014A - Metal powder manufacturing method - Google Patents

Abstract

PURPOSE:To allow the continuous production of metallic powder having stable quality, the reduction of a cost, the elimination of the possibility of impurity intrusion, the avoidance of the hole clogging of an injection nozzle and the production of the metallic powder consisting of finer particles. CONSTITUTION:A cooling liquid layer 7 which flows down while swirling along the inner peripheral surface of a cylindrical body 1 for cooling is formed by ejecting and supplying the cooling liquid along the inner peripheral surface of the cylindrical body 1 of the apparatus for producing the metallic powder which produces the metallic powder by supplying a molten metal to the cooling liquid in the cylindrical body 1 and cooling and solidifying the molten metal. The cooling liquid is simultaneously discharged from the lower part of the cylindrical body 1 and an arc is generated between a metallic material 16 and an electrode rod 18 disposed in such a manner that the ends are proximate to each other on the inner peripheral surface side of the cooling liquid layer 7, by which a metallic material 16 is melted. The centrifugal force heading toward the cooling liquid layer 7 is imparted to the molten metal to splash and supply the molten metal toward the cooling liquid layer 7. The molten metal is thus parted, cooled and solidified by the cooling liquid layer 7.

Description

[Detailed description of the invention]

0001

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

0002

[Prior Art] Rapidly solidified metal powder has fine crystal grains and can contain supersaturated alloying elements. It has exceptional material properties and is attracting attention as a material for mechanical parts.

[0003] A preferred method for producing the rapidly solidified metal powder is a rotating 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.
In this method, a molten metal is formed by the action of centrifugal force, and molten metal is injected into the cooling liquid layer 62 to obtain finely divided metal powder that is rapidly solidified. In the same figure, reference numeral 63 denotes an injection crucible as a means for supplying molten metal, a high frequency coil 64 for heating is attached to the inner peripheral surface of the crucible, and an injection nozzle 6 is attached to the lower side wall of the crucible.
5 have been established. Molten metal 66 in the crucible 63
is injected from the nozzle 65 by injecting an inert gas 67 into the crucible 63 under pressure. When a certain amount of metal powder accumulates in the cooling drum 61, the rotation of the cooling drum 61 is stopped and the metal powder is collected together with the cooling liquid.
dried. The method for producing such metal powder is described in Japanese Patent Publication No. 1-4.
It is disclosed in Publication No. 9769.

0004

However, the rotating drum method involves a so-called batch operation, resulting in poor productivity. Furthermore, since the injection of molten metal must be stopped during powder recovery, there is a problem in that the injection nozzle is likely to become clogged. In addition, in order to keep the cooling temperature constant,
The temperature must be controlled by supplying and discharging the cooling liquid from the liquid level of the cooling liquid layer 62, but at this time, there is a problem that the liquid level is disturbed and variations in powder particle size and quality are likely to occur.

Furthermore, an injection crucible is used to supply the molten metal to the cooling liquid layer 62, which increases the cost and raises the risk of contamination with impurities. Furthermore, the size of the injection nozzle 65 cannot be made very small from the viewpoint of hole clogging, and therefore there is a limit to reducing the amount of molten metal 66 ejected. 66 was continuously supplied directly to the same position of the cooling liquid layer 62, making it difficult to obtain metal powder with finer particles.

In view of the above-mentioned problems, the present invention has been devised to make it possible to continuously produce metal powder of stable quality, without the fear of clogging of the injection nozzle or contamination with impurities, and with finer particles. It is an object of the present invention to provide a metal powder manufacturing method capable of manufacturing particulate metal powder.

[0007]

[Means for Solving the Problems] The technical means taken by the present invention to achieve the above object is to supply molten metal to a cooling liquid in a cooling cylinder 1, cool and solidify it, and produce metal powder. In this method, a cooling liquid is jetted and supplied along the inner circumferential surface of the cylinder 1 to form a cooling liquid layer 7 that flows down while swirling along the inner peripheral surface of the cylinder 1, and the cooling liquid is supplied to the cylinder. 1 The metal material 16 is discharged from the lower part and an arc is generated between the metal material 16 and the electrode rod 18 whose ends are arranged close to each other on the inner peripheral surface side of the cooling liquid layer 7 to melt the metal material 16. A centrifugal force directed toward the cooling liquid layer 7 is applied to the molten metal to scatter and supply the molten metal toward the cooling liquid layer 7 .
The point is to separate the particles and cool and solidify them.

[0008]

[Operation] The cooling liquid supplied along the inner peripheral surface of the cooling cylinder 1 flows down while swirling along the inner peripheral surface of the cylinder, and due to the action of centrifugal force during the rotation, the cooling liquid layer has an approximately constant inner diameter. Form 7. Then, an arc is generated between the metal material 16 whose ends are arranged close to each other on the inner peripheral surface side of the cooling liquid layer 7 and the electrode rod 18 to melt the metal material 16 and drive the metal material 16 to rotate. or by rotationally driving the electrode rod 18.
By causing the molten metal to fall and collide with the cooling liquid layer 7 , a centrifugal force is applied to the molten metal toward the cooling liquid layer 7 , and the molten metal is scattered and supplied toward the cooling liquid layer 7 . Then, the molten metal droplets supplied to the cooling liquid layer 7 are separated by the swirling flow of the cooling liquid layer 7, and are cooled and solidified to produce metal powder.

Since the cooling liquid layer 7 is always formed by freshly supplied cooling liquid, a constant temperature can be easily maintained. Therefore, there is no need to drain or supply cooling liquid from the liquid surface for temperature control, and the liquid level is not disturbed and a stable state is maintained. Therefore, the molten metal supplied to the cooling liquid layer 7 is always supplied and divided into the cooling liquid layer under constant conditions, and is 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 7 flows down while swirling together with the cooling liquid, and is discharged from the lower part of the cylinder 1, thereby making it possible to continuously produce metal powder. Further, an injection crucible is not required to supply the molten metal, which reduces costs, reduces the possibility of contamination with impurities, and prevents clogging of the injection nozzle of the injection crucible.

Furthermore, since the molten metal is scattered and supplied toward the cooling liquid layer 7, metal powder with finer particles can be produced.

0012

EXAMPLES First, an apparatus for carrying out the method for producing metal powder of the present invention will be described. FIG. 1 shows a metal powder manufacturing apparatus according to an embodiment, and in the figure, 1 is a cooling cylinder, which is formed into a cylindrical shape with a bottom that opens upward.
The upper end opening of this cylindrical body 1 is closed by a lid body 2 . A plurality of coolant jetting pipes 3 are formed at equal intervals in the circumferential direction in the upper part of the cylinder 1, and the discharge ports 4 of the jetting pipes 3 are configured to jet and supply the cooling liquid from a tangential direction along the inner peripheral surface of the cylinder. It is opened to Further, the pipe axis direction of the ejection pipe 3 is 0 to 20° with respect to the horizontal tangent to the inner circumferential surface of the cylinder body 1.
It is set diagonally downward. The jet pipe 3 is connected via a pump 5 to a tank 6, and the pump 5 sucks up the coolant in the tank 6 and supplies it to the inner peripheral surface of the cylinder 1 from the jet pipe 3. Then, on the inner circumferential surface of the cylinder body 1, from the lid body 2 to the cylinder body 1 and the bottom wall 1.
A cooling liquid layer 7 is formed which flows downward while swirling along the inner circumferential surface. The tank 6 is provided with a cooling liquid supply pipe for replenishment (not shown), and a cooler may be appropriately interposed within the tank 6 or in the middle of the circulation flow path. Water is generally used as the coolant, but oil may also be used. In addition, when using water, it is desirable to use water from which dissolved oxygen has been removed. Oxygen removal processing equipment is commercially available and easily available.

A cooling liquid layer 7 is provided at the lower part of the inner peripheral surface of the cylinder 1.
A layer thickness adjusting ring 8 is detachably and replaceably attached with a bolt, and this ring 8 suppresses the flow rate of the coolant, thereby easily forming a coolant layer 7 having a substantially constant inner diameter. Further, on the outer periphery of the bottom wall 1a of the cylindrical body 1, a plurality of outlets 9 (or one outlet) are provided which open downward. A container 10 is disposed, and in this separation container 10, a mesh member 11 is disposed in an inclined manner through which the cooling liquid can pass downwardly, but through which the metal powder cannot pass. In addition, separation container 1
A powder discharge port 12 is formed on the lower side of the side wall of the mesh member 11 in the inclination direction, and a drain port 13 is formed at the bottom, and the drain port 13 is piped to the tank 6 .

Lid body 2 of cylinder body 1 The lid body 2 is located at the center of the cylinder body 1.
A communication pipe 14 passing through is fixed, and a closed space 15 on the inner peripheral surface side of the cooling liquid layer 7 is communicated with the outside through the communication pipe 14.
The space 15 can be filled with an inert gas such as Ar gas or N2 gas, or the air inside the space 15 can be extracted to create a vacuum state. Further, a metal material 16 formed in a rod shape is inserted into the cylindrical body 1 from above, passing through the communication pipe 14. This metal material 16 is supported to be rotatable about an axis in the vertical direction and movable downward, and is rotationally driven and moved downward by a drive device (not shown). Further, the metal material 16 is connected to the positive side of the power source via a brush 17 that is in sliding contact with the metal material 16. An electrode rod 18 is disposed below the metal material 16 and inserted into the cylinder 1 from below through the bottom of the separation container 10 and the bottom wall 1a of the cylinder 1. The ends of 18 are close to each other and are vertically opposed to each other. The electrode rod 18 is made of a heat-resistant material such as tungsten that is not easily consumed, and is airtightly supported and fixed to the bottom wall 1a of the cylindrical body 1 via an insulating material 19 at the upper and lower intermediate portions, and is also supported and fixed at the bottom. . Further, the electrode rod 18 is connected to the negative side of the power source, so that an arc can be generated between the metal material 16 and the electrode rod 18.

In the above structure, in order to produce metal powder, first, the pump 5 is operated to form the cooling liquid layer 7 on the inner peripheral surface of the cylinder 1, and then the cooling liquid layer 7 is formed on the inner peripheral surface side. An inert gas is pumped into the space 15 through the communication pipe 14. Then, the air in the space 15 is discharged to the outside together with the cooling liquid, and the space 15 is filled with inert gas. After the space 15 is filled with the inert gas, it is not necessary to constantly supply the gas, and it is sufficient to shut off the on-off valve provided between the communication pipe 14 and the gas source. Note that in order to easily perform the replacement with inert gas, it is sufficient to provide another communication pipe for air exhaust. Alternatively, the air in the space 15 may be drawn out from the communication pipe 14 using a vacuum pump or the like without replacing the air in the space 15 with an inert gas to make the space 15 in a vacuum state. After that, the metal material 16
An arc is generated between the metal material 16 and the electrode rod 18, and the metal material 16 is melted by the heat generated by the arc.
is rotated to scatter the molten metal radially toward the cooling liquid layer 7 by the action of centrifugal force. At this time, metal material 1
6 is gradually sent downward as the material decreases. Then, the scattered droplets are divided by the cooling liquid layer 7 flowing downward while swirling, and are rapidly solidified to produce metal powder. This metal powder is produced by supplying molten metal to the cooling liquid layer 7 in a vacuum or inert gas atmosphere.
Surface oxidation of the molten metal is suppressed during the process, resulting in a high-quality powder with a thin acid film. The metal powder in the cooling liquid layer 7 flows down over the layer thickness adjustment ring 8 while swirling together with the cooling liquid, and enters the separation container 10 from the discharge port 9 at the lower end of the cylinder 1 . Here, the metal powder and the cooling liquid are separated by the mesh member 11, and the metal powder with a small liquid content is obtained by temporarily removing the liquid. This primary deliquified metal powder is discharged from the powder discharge port 12,
The liquid is removed by a dehydrating device such as a centrifuge, and then dried by a drying device. In addition, the coolant flows from the drain port 13 to the tank 6.
It is returned and used for circulation.

[0016] In the above-mentioned embodiments, a cylindrical cooling cylinder is shown, but the cooling cylinder is not limited to this. It may also have a funnel shape or a truncated inverted conical shape. In this case, a cooling liquid layer with a constant inner diameter can be formed without attaching a layer thickness adjustment flange. Further, the rotation direction of the metal material 16 is
It may be in the same direction or in the opposite direction to the direction of movement of the swirling flow of the cooling liquid layer 7, but it is better to move in the direction opposite to the swirling flow.
A good breaking effect is achieved by the swirling flow of the molten metal droplets scattered from the metal material 16. Further, by changing the rotational speed of the metal material 16, the size of the powder particles can be easily controlled.

Furthermore, the metal material 16 and the electrode rod 18 may be upside down, and as shown in the figure, the metal material 1
6 is on the upper side and the electrode rod 18 is on the lower side, the metal material 16
The electrode rod 18 is rotated without being rotationally driven, and the molten metal falling from the metal material 16 is hit by the electrode rod 18 and centrifugal force is applied from the electrode rod 18 to scatter and supply it toward the cooling liquid layer 7. In that case, it is preferable to fix the rotary table 20 to the upper end of the electrode rod 18, as shown in FIG. In addition, as shown in FIG.
Provided at the upper end, the cylindrical shaft 21 is rotated around the axis without rotating the electrode rod 18, and only the rotary table 20 is rotated.
The molten metal falling from the metal material may be scattered toward the cooling liquid layer 7. In this case, the electrode rod 18 may be fixed, but in consideration of the case where the electrode rod 18 is worn out, the electrode rod 18 may be fixed. Preferably, the rod 18 is extended upwardly. In addition, by forming the metal material 16 relatively long or conveying it continuously, continuous productivity of metal powder can be improved.

The bottom wall 1a of the cylindrical body 1 is sloped downward from the center toward the discharge port 9 for easy drainage.
(If there is only one outlet 9, the entire bottom wall 1a is preferably formed to be inclined downward toward the outlet 9.) Further, in the illustrated example, the layer thickness adjustment ring 8 has a rectangular cross section, but it is not limited to this, and may be formed with a curved surface whose diameter gradually decreases from the outer circumferential edge of the upper surface to the inner circumferential edge of the lower surface, for example.

The present invention is of course 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.

[0020]

[Effects of the Invention] According to the present invention, the cooling liquid is jetted and supplied along the inner circumferential surface of the cylinder 1 to form a cooling liquid layer 7 that flows down while swirling along the inner circumferential surface of the cylinder 1. Therefore, the molten metal can be stabilized on the inner peripheral surface of the cooling liquid layer 7 that supplies the molten metal, and the temperature can be maintained uniformly. Since molten metal is supplied into the cooling liquid layer 7, rapidly solidified powder with stable quality can be continuously produced.

Further, an arc is generated between the metal material 16 and the electrode rod 18, and the heat generated by the arc melts the metal material 16 on the inner peripheral surface side of the cooling liquid layer 7. 16 and the electrode rod 18 are arranged to face each other vertically, and the metal material 16 is rotated around the axis in the vertical direction, or the metal material 16 is arranged on the upper side and the electrode rod 18 is arranged on the lower side. Apply centrifugal force to the molten metal toward the cooling liquid layer 7 by driving the rod 18 to rotate around the axis in the vertical direction so that the molten metal falling from the metal material 16 hits the electrode rod 18. Since the molten metal obtained by melting the metal material 16 is supplied to the cooling liquid layer 7 by the action of this centrifugal force, in order to supply the molten metal to the cooling liquid layer 7, There is no need to use an injection crucible as in the conventional method, and therefore, costs can be reduced, there is less risk of contamination with impurities, and the situation of clogging of the injection nozzle can be avoided.

Furthermore, since the molten metal is scattered and supplied toward the cooling liquid layer 7 by the action of centrifugal force, it is possible to produce metal powder with finer particles.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional overall layout diagram of main parts of a metal powder manufacturing apparatus for carrying out the present invention.

FIG. 2 is a sectional view of a main part showing another example for carrying out the present invention.

FIG. 3 is a sectional view of a main part showing another example for implementing the present invention.

FIG. 4 is a sectional view of a main part of a conventional metal powder manufacturing apparatus.

[Explanation of symbols]

1 Cooling cylinder 7 Cooling liquid layer 16 Metal materials 18 Electrode rod

Claims (1)

[Claims] 1. A method of producing metal powder by supplying molten metal to a cooling liquid in a cooling cylinder (1) and cooling and solidifying the metal, wherein the cooling liquid is supplied along the inner circumferential surface of the cylinder (1). is jetted out to form a cooling liquid layer (7) that flows down while swirling along the inner peripheral surface of the cylinder (1), and the cooling liquid is discharged from the lower part of the cylinder (1) to form a cooling liquid layer (7). ) A metal material (16) whose ends are arranged close to each other on the inner peripheral surface side of the metal material (16)
An arc is generated between the metal material (16) and the electrode rod (18) to melt the metal material (16), and a centrifugal force is applied to the molten metal toward the cooling liquid layer (7) to cause the molten metal to flow into the cooling liquid layer (7). ) A method for producing metal powder, characterized in that the metal powder is supplied by scattering toward the cooling liquid layer (7), divided by the cooling liquid layer (7), and cooled and solidified.