JPS63145703A - Apparatus for producing powder - Google Patents

Abstract

PURPOSE:To maintain the high purity of a molten metal and to increase the output thereof by using a water-cooled divided copper crucible as a melting crucible provided with a high-frequency induction heating coil on the outer periphery thereof. CONSTITUTION:A metallic material is charged into the water-cooled divided copper crucible 63, the inside wall of which is formed by connecting water- cooled copper segments 81 divided in the longitudinal direction via insulating refratories 82. After a prescribed inert atmosphere is maintained in a hermetic chamber 60, the above-mentioned heating coil 64 for the crucible 63 is energized. The induction current hardly flows in the crucible 63 at this time and efficiently heats and melts the metallic material in the crucible 63 so that a thin solidified shell 74 of the molten metal 72 itself is formed and the inside wall of the crucible 63 is protected by the self-coating. The molten metal 72 is then dropped from a nozzle 65 heated by the induction heating coil 66 for the nozzle 65 onto a disk 69 rotating at a high speed and is splashed by centrifugal force, by which the fine powder is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to a powder manufacturing apparatus for manufacturing metal powder used in powder metallurgy and the like.

[Prior Art] Powder metallurgy is a technology for manufacturing metal products or metal ingots by charging metal or alloy powder into a mold, press-molding it, and then sintering the molded body. In powder metallurgy, segregation of component elements does not occur, it is possible to commercialize materials that are difficult to process, it is possible to produce parts with extremely fine crystal structures, and it is possible to make non-equilibrium phases appear. There are various advantages that cannot be obtained with melted lumber, such as this, and there is also the advantage that secondary cutting can be omitted. For this reason, various powder manufacturing techniques applied to powder metallurgy have been developed.

Among these, the spray method is widely used because it is suitable for production on an industrial scale and powder can be produced using relatively simple equipment.

There are two typical spraying methods: an argon gas spraying method and a vacuum spraying method. FIG. 3 is a schematic diagram showing the argon gas atomization method. In the argon gas atomization method, molten metal 1 stored in a container 2 flows out from a nozzle 3 provided at the bottom of the container 2, and argon gas 4 is sprayed with high energy into the flowing molten metal flow to atomize the molten metal. Powder 5 is obtained by doing this.

FIG. 4 is a schematic diagram showing the vacuum rtmn method. In the vacuum spraying method, high-pressure gas 15 is blown into the molten metal 11 in the container 12 to make the molten metal 11 supersaturated with the gas 15, and the mixture of molten metal and gas is depressurized through the nozzle 13 by an appropriate exhaust means. The molten metal 11 is sprayed and scattered by the expansion pressure of the gas 15 to obtain a powder 16.

1 at the same production scale as the gas atomization method and vacuum atomization method described above.
Rapid solidification is a method that can produce fine and uniform powder of 11111. FIG. 5 is a schematic diagram showing the rapid solidification method. In this rapid solidification method, a metal lump is melted in a container 21 by passing a high frequency current through an 8-frequency coil 22, and the molten metal 23 produced here is dropped onto a disk 24 rotating at a high speed, and the rotation of this disk 24 is performed. The molten metal 23 is scattered. Then, this scattered molten metal 23 is rapidly solidified using a cooling medium with high thermal conductivity such as hydrogen gas or helium gas.

Rotating electrode method, centrifugal granulation method and E B RD (E 1ectron 3 ean +
There is a RotatingDisk method. FIG. 6 is a schematic diagram showing the rotating electrode method. In the rotating electrode method, the sixth
As shown in the figure, an arc 33 is formed between the consumable R pole 31 and the non-consumable electrode 32, and at this time, the consumable electrode 31 is rotated at high speed by a rotating means (not shown) such as a motor. A powder 35 is obtained by scattering droplets 34 generated by melting the consumable electrode 31 .

FIG. 7 is a schematic diagram showing the centrifugal granulation method. In the centrifugal granulation method, an arc 43 is formed between a crucible 41 that is rotatably installed in an argon gas atmosphere and an electrode 42 that is installed vertically, and the crucible 41 is rotated while being cooled with water to form an electrode 42. A droplet 44 formed by melting is placed in a crucible 41.
By dropping the liquid 144 into the container, the liquid 144 is scattered and powder is generated.

FIG. 8 is a schematic diagram showing the EBRD method.

In the EBRD method, under high vacuum (for example, 104T o
rr or less), the rod-shaped master alloy 51 is melted by the electron beam 53 from the electron gun 52, and droplets 54 are dropped.
4 is scattered by a high-speed rotating disk 55 below to obtain powder.

[Problem to be solved by the invention 1 Each of the above methods has its own drawbacks.

First, in the case of the argon gas atomization method, a container 2 for storing molten metal 1. There is a risk that impurities may enter from the nozzle 3 and the atomizing gas 4, and in the case of the vacuum spray method and rapid solidification method, there is a risk that impurities may enter from the containers 12 and 21, respectively. There is a problem in that it is difficult to produce powder with high purity.

In the case of the rotating electrode method and the centrifugation method, although there is less contamination of impurities than in the case of the above-mentioned method, each method is non-consumable.
tf! There is impurity contamination from 32 and crucible 41. In addition, in the case of these methods, the consumable electrode 21 made of the alloy to be obtained and the crucible 41 acting as a water-cooled electrode need to be rotated at high speed in order to obtain powder with small particle size. However, in order to rotate these electrodes at high speeds, it is extremely difficult to manufacture and maintain the equipment due to the precision of electrode processing and rotation technique, and it is difficult to use on an industrial scale such as the argon spray method mentioned above. Production cannot be expected.

This invention was made in view of the above circumstances, and aims to provide a powder manufacturing device that can manufacture high-purity powder of titanium alloys, superalloys, etc. used in powder metallurgy, and is also excellent in terms of manufacturing and maintenance. It is something to do.

[Means for solving the problem] A powder manufacturing apparatus according to the present invention includes a crucible equipped with a high-frequency induction heating coil on the outer periphery, and a molten metal disposed below the crucible that scatters molten metal falling from the crucible by rotation. The crucible is composed of water-coolable copper segments whose inner wall is divided in the vertical direction, and an insulating refractory material is filled between the segments. It is characterized by being a water-cooled divided copper crucible.

[Operation] In the present invention, the metal material charged into the crucible is melted by applying electric power to a high frequency induction heating coil provided on the outer periphery. In this case, the water-cooled divided copper crucible is composed of water-cooled copper segments divided in the vertical direction, and an insulating refractory is filled between the segments. Therefore, no current induced by the heating coil flows through the crucible, and the crucible efficiently melts the metal material inside. In addition, since the crucible is composed of water-cooled copper segments, when the metal material charged in the crucible is melted, a part of it forms a solidified shell on the inner wall of the crucible, and the inner wall of the crucible is self-coated. Prevents contamination with impurities.

After the composition of the metal melted in the crucible, that is, the molten metal is adjusted, it is dropped from a nozzle provided at the bottom of the crucible onto a disk provided below. The disk is provided to be able to rotate at high speed, and the F that falls onto the disk rotating at high speed.
The IN is scattered by the centrifugal force, rapidly cooled and turned into metal powder.

When a nozzle is used as in the illustrated embodiment, the following can be done in order to prevent impurities from the nozzle from being mixed into the core temperature when the molten metal passes through the nozzle.

The nozzle is a water-cooled divided copper nozzle, equipped with a high-frequency induction heating coil on the outer periphery, and a metal plug is inserted in advance before the metal material charged into the melting hole is melted. This metal stopper is made of a metal with the same composition as the target metal powder or a low melting point typhoon, and when the FJ'A in the crucible is dropped onto the disk, power is applied to the heating coil installed on the outer periphery of the nozzle. Apply voltage to melt the metal stopper and drop it to open the nozzle.

By doing this, the inside of the nozzle is self-coated to prevent impurities from the inner wall of the nozzle from getting mixed in with the core temperature passing through the nozzle, similar to the effect of preventing impurities from the crucible mentioned above. .

Furthermore, instead of using a nozzle, the crucible can be provided with a tilting device, and the molten metal in the crucible can be caused to fall onto the aforementioned disk that rotates at high speed by tilting the crucible.

[Example J] Hereinafter, the powder manufacturing apparatus of the present invention will be described with reference to the accompanying drawings. FIG. 1 shows a powder manufacturing apparatus according to the present invention. The airtight chamber 60 is provided with an exhaust port 61 connected to an exhaust means (not shown) such as a vacuum pump, and a gas inlet 62 connected to a gas supply device (not shown). The inside of the airtight chamber is under vacuum (for example, 10 →
TOrr) or by introducing a gas such as A gas or He gas to maintain an inert atmosphere.

Inside the airtight chamber, a water-cooled divided copper crucible 63 and a water-cooled divided copper nozzle 65 directly connected to its lower part are provided, which will be described later.
It has been done.

A raw material hopper 67 is provided above the crucible 63, and a disk 69 is rotatably installed below the nozzle 65 with its surface facing upward, and is rotated about a vertical axis 71 by a rotating device 70. do.

High-frequency electric 'rA equipment and other attachments (not shown)
Needless to say, a is provided.

FIG. 2 is a schematic diagram of a water-cooled divided copper crucible. As shown in the figure, a high frequency induction heating coil 64 is provided on the outer periphery of the crucible.
The crucible wall holding the molten metal 72 inside is assembled into a cylindrical shape by a plurality of water-cooled copper segments 81 divided in the vertical direction, and a refractory insulator 82 such as CaF2 is filled between the segments. ing.

When a cylindrical ¥1lfi%J crucible is placed inside the high frequency coil 64, an annular induced current flows through the crucible wall and generates heat, wasting power and heating the crucible to a high temperature. Impurities tend to get mixed into the molten metal inside the crucible. However, if the crucible is divided vertically and electrically insulated from each other as described above, this circular current is blocked and heating of the crucible is avoided, resulting in unnecessary power consumption and impurities as described above. Contamination can be avoided.

The water-cooled dividing nozzle also has the same structure as the water-cooled dividing crucible shown in FIG. 2, except for the size difference.

The functions of the powder manufacturing device configured in this way,
The effect will be explained.

First, the metal material to be melted is charged into the crucible 63 and the raw material hopper 67, and then after operations such as evacuation and gas introduction are performed to create the required inert atmosphere in the airtight chamber 60, the induction heating coil for the crucible 63 is charged. Turn on the high frequency power to 64. In this case, almost no induced current flows through the water-cooled dividing crucible 63 configured as shown in FIG. 2, and the metal material inside the crucible 63 is directly heated and melted efficiently. Also,
When the metal material f1 is partially melted to form a molten metal, the crucible 63
Since no high-frequency current flows through the crucible 63, the temperature of its inner wall is low, and a thin solidification shelf 4 is formed, and the inner wall of the crucible 63 is protected by self-coating.

Before melting the metal material, a metal stopper having the same composition as the metal material or having a low melting point is inserted into the nozzle 65 to prevent the molten metal from falling from the nozzle 65 during melting.

When all the metal materials previously charged into the crucible 63 are melted into molten metal, the composition of the molten metal is adjusted by adding an alloy material from the raw material hopper 67, and then a nozzle is opened. The opening of the nozzle 65 is performed by applying a high frequency power to an induction heating coil 66 provided on the outer periphery of the nozzle 65 to melt and drop a metal plug that has been fitted in advance. For this reason, the nozzle 65 also has a divided structure like the crucible 63.

In this way, the molten metal 72 is dropped to a position close to the periphery of the disk 69, but since the disk 69 is rotating at a speed of, for example, 10,000 to 30,000 rpm by the rotation Hffi 70, the molten metal that has fallen onto the disk 69 is rotated by its centrifugal speed. It is dispersed by force and a fine powder is obtained.

By the way, in order to prevent falling objects from getting into the nozzle hole when the nozzle is opened, a shield is placed above the disk in advance, and after the metal plug falls, this shield is moved to the side and the disk is closed. All you have to do is make it fall.

Specific specifications showing one example of the powder production IA apparatus of the present invention will be described. The melting material used at this time was nickel-based high alloy IN-100, the composition of which is shown in Table 1 below.

The water-cooled split crucible 63 has an inner diameter of 120Mφ and a height of 200M.
, the number of divisions of the water-cooled copper segment 81 is 24, the inner diameter of the induction heating coil 64 of the crucible is 180 mm, the frequency of the high-frequency power applied to it is 100 kHz, and the output is 200 k~■
, the water-cooled dividing nozzle 65 has an inner diameter of 20 mmφ, the number of divided water-cooled copper segments is 12, and the induction heating coil 66 of the nozzle.
has an inner diameter of 60 m, and the high frequency power applied to it has a frequency of 10
0kHz, output 100kW.

The material of the metal plug fitted into the nozzle is lN-1 in Table 1.
It was set as 00. The disk 69 has a diameter of 100 m.

Rotation fi20. OOOrpm, inner diameter of airtight chamber 60 1T
'rL, and the atmosphere was He0.1 atm.

In the above manner, an IN-100 alloy powder having an average particle size of 120 μm was obtained. The amount of nonmetallic inclusions in the alloy powder obtained here was determined by melting in a crucible using the conventional technique, gas injection n (third
The results were compared with the case of alloy powder obtained by the argon gas atomization method (Fig. 1). The amount of inclusions was compared by measuring the inclusions floated to the surface by button melting using an electron beam button melting method. As a result, the amount of inclusions in the alloy powder obtained by the method of the present invention was 1/7 of that by the prior art.

The present invention is also effective in producing powders of superalloys, pure metals, etc., which avoid contamination from refractories, in addition to IN-100 mentioned in the examples.

[Effects of the Invention] Comparing the powder manufacturing apparatus of the present invention with the prior art described above, first, the conventional argon gas atomization method (Fig. 3), vacuum atomization method (Fig. 4), and rapid granulation method ( Figure 5) all use a refractory material container as a melting crucible or core temperature storage container, and contamination due to impurities from the crucible is unavoidable, making it difficult to produce high-purity high-alloy and superalloy powders. is not suitable.

Next, the rotating electrode method (Fig. 6), centrifugal granulation method (Fig. 7), and EBRD method (Fig. 8) all consume 1! This is a powder manufacturing device that combines electrode melting, dropping, and scattering by centrifugal force, and contamination of the metal powder by impurities is relatively low, but it requires a step in advance to process the target component metal as a consumable N electrode. When the material is difficult to process, there are further technical difficulties, leading to increased costs.

On the other hand, the powder manufacturing apparatus of the present invention uses a water-cooled divided copper crucible as a melting crucible, and a part of the molten metal is fused to the inner wall of the crucible to create a solidified shell, which becomes a self-coating part of the crucible. The high purity of the molten metal is maintained because it prevents impurities from entering from the inner wall. In addition, since no consumable electrodes are used, the cost of powder production can be reduced, and since the powder production equipment uses a melting furnace, production capacity can be easily expanded.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of a powder manufacturing apparatus according to an embodiment of the present invention, Fig. 2 is a schematic diagram showing a water-cooled divided copper crucible in the Vl position, and Figs. 3 to 8 are respectively different conventional powder manufacturing apparatuses. FIG. 60...Airtight chamber, 61...Exhaust port, 62...Gas inlet, 63...Water-cooled divided copper crucible, 64...High frequency induction heating coil for crucible, 65...Water-cooled divided copper nozzle , 66... High frequency induction heating coil for nozzle, 67...
...Raw material hopper, 68...Alloy material, 69...Disk, 70...Rotating device, 81...Water-cooled copper segment, 82...Insulating refractory. Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 Fig. 7 Fig. 8 Procedure Ne City Official Book 1, Incident Indication Patent Application No. 1982-292760 2, Name of Invention Powder Manufacturing Apparatus 3 , Relationship with the case of the person making the amendment Patent applicant (412) Nippon Kokan Co., Ltd. 4, Agent UBE Building 7, 3-7-2 Kasumigaseki, Chiyoda-ku, Tokyo;
Contents of the amendment (1) On page 5, line 18 of the specification, the words ``high alloy, as there is a risk of contamination'' have been replaced with ``TI, high alloy, as there is a possibility of contamination.''
``Active metals such as Ti alloys, high alloys''. (2) Add the following text between lines 12 and 13 on page 6 of the same document. Also, in the EBRD method, components evaporate due to the high vacuum. Furthermore, rotating electrode method and centrifugation method. In the EBRD method, it is necessary to prepare in advance an electrode rod or rotating rod having the same composition as the powder to be obtained, and the manufacturing cost is high. Therefore, instead of these methods, it is desired to obtain powder directly from molten metal. (3) On page 14, line 20, the phrase “Refractories in addition to 100” was replaced with “In addition to 100, T.
i, active metals such as Ti alloys and refractories.''

Claims (4)

[Claims] (1) A powder manufacturing apparatus comprising, in an airtight chamber, a crucible having a high-frequency induction heating coil on its outer periphery, and a disk disposed below the crucible that scatters molten metal falling from the crucible by rotation. A powder manufacturing apparatus characterized in that the crucible is a water-cooled divided copper crucible whose inner wall is composed of copper segments divided in the vertical direction and connected via an insulating refractory material. (2) The powder manufacturing apparatus according to claim 1, wherein the water-cooled divided copper crucible includes a nozzle connected to a lower part of the crucible, and the molten metal is dropped onto a disk from the nozzle. (3) The powder manufacturing apparatus according to claim 1 or 2, wherein the nozzle is a water-cooled divided copper nozzle equipped with a high-frequency induction heating coil on its outer periphery. (4) The powder manufacturing apparatus according to claim 1, wherein the water-cooled divided copper crucible is equipped with a tilting device, and the molten metal in the crucible falls onto the disk by tilting the crucible.