JPH0714340Y2 - Molten metal nozzle for producing metal powder - Google Patents

Description

[Detailed Description of the Invention] A. Purpose of the Invention (1) Industrial Application Field The present invention relates to a molten metal nozzle for producing metal powder, and in particular, to a molten metal nozzle used when producing metal powder under the application of the gas atomization method. Regarding improvement.

(2) Conventional Technology Conventionally, as this kind of molten metal nozzle, a throttle is provided at the outlet of the flow path and a gas flow is contacted around the outlet in order to make the metal powder finer. A restraint type molten metal nozzle is known.

(3) Problems to be Solved by the Invention However, in the above-mentioned molten metal nozzle, the vicinity of the molten metal outlet is cooled by the gas flow, and the amount of molten metal at the molten metal outlet is small due to the throttling. There is a problem that the nozzle is likely to be clogged by solidifying in the molten metal nozzle.

The present invention has been made in view of the above circumstances, and an object thereof is to provide the molten metal nozzle capable of reliably avoiding nozzle clogging.

B. Configuration of the Invention (1) Means for Solving the Problems The present invention is a molten metal nozzle used when a metal powder is manufactured under the application of the gas atomizing method, and is provided in an intermediate portion of a vertically extending flow path. It is characterized in that a throttle for changing the molten metal flow into a droplet flow for dropping is provided.

(2) Action With the above-mentioned configuration, the droplet flow is dropped from the outlet of the molten metal nozzle without adhering to the inner peripheral surface of the flow path, so that the gas flow around the outlet is aimed at making the metal powder finer. It is possible to reliably avoid the nozzle clogging caused by the solidification of the molten metal even when the molten metal is brought into contact with.

(3) Example In FIGS. 1 and 2, a metal powder manufacturing apparatus for carrying out the He gas atomization method comprises a powder manufacturing section 1 and a powder collecting section 2, and the powder manufacturing section 1 melts the upper part. It comprises a chamber 3 and a spray chamber 4 at the bottom, and the powder recovery part 2 comprises a cyclone 5 at the top and a recovery pot 6 at the bottom.
The atomization chamber 4 and the cyclone 5 are connected via a conduit 7.

A crucible 8 is provided in the melting chamber 3, and the crucible 8 is
The melt nozzle 9 attached to the bottom wall of the spray chamber is located in the upper part of the spray chamber 4. The melt nozzle 9 is a flow path extending in the vertical direction.
10 has its inlet 11 opening into the crucible 8;
The outlet 12 opens downward from the melt nozzle 9.
An annular gas nozzle 14 is attached to the outer peripheral surface of the lower portion of the molten metal nozzle 9, and a gas introduction pipe 15 is connected to the gas nozzle 14.
A stopper 16 is inserted into the crucible 8 and the stopper 16
Thus, the inflow port 11 of the molten metal nozzle 9 can be closed.

The molten metal nozzle 9 is formed with a taper surface 17 that is tapered from the outer peripheral edge of the outlet 12 to a predetermined position on the lower outer peripheral surface. The gas flow g by the gas nozzle 14 is formed in a conical shell shape so as to converge along the center extension line of the outlet 12 after following the tapered surface 16. As a result, the gas flow g comes into contact with the outer peripheral edge of the outlet 12 of the molten metal nozzle 9.

In the melt nozzle 9, a throttle 18 is provided at an intermediate portion of the flow path 10, that is, at a position biased toward the inflow port 11 side in the illustrated example, and the melt flow is decompressed by the throttle 18 and converted into a droplet flow. Also, the outer peripheral surface of the melt nozzle 9 surrounding the throttle 18 is kept warm (or heated).
Block 19 is attached. When the throttle 18 is arranged in the high temperature region of the flow path 10 that receives the heat of the molten metal in the crucible 8 and the heat of the heat retaining (or heating) block 19 in this way, solidification of the molten metal flow existing in the throttle 18 is prevented.

In the production of the metal powder, a molten metal m of, for example, an aluminum alloy is prepared in a crucible 8 as shown in FIG. 2, and the molten metal m is made to flow through a molten metal nozzle 9 by applying a back pressure thereto. Introduce to road 10. Further, He gas as an atomizing gas is supplied to the gas introduction pipe 15, and the He gas is ejected from the gas nozzle 14 to form a gas flow g.

The molten metal flow m ₁ introduced into the molten metal nozzle 9 is reduced in pressure by passing through the restrictor 18 and converted into a droplet flow m ₂ . As a result, the droplet flow m ₂ is dropped from the outlet 12 of the molten metal nozzle 9 without adhering to the inner peripheral surface of the flow channel 10, and is cut into fine metal powder Pm by the gas flow g. In this case, since the droplet flow m ₂ is cooled during the dropping, it is possible to avoid the mutual bonding of the powders after being pulverized and maintain the fine state when pulverized.

When such a drop of the droplet flow m ₂ is revealed, the metal powder Pm
No nozzle clogging occurs even if the gas flow g is brought into contact with the periphery of the outlet 12 for the purpose of miniaturization.

In order to obtain the above action, the molten metal nozzle 9 and the like are required to have the following various requirements. However, in FIG. 3, a is the inner diameter of the diaphragm 18, b is the length of the diaphragm 18, and c is the flow path 10.
In FIG. 2, α is the inner diameter of the downstream side of the throttle 18, α is the angle formed by the extended busbar on the outlet 20 side of the throttle 18 and the continuous surface 21 of the flow passage 10 with the throttle 18, and in FIG. And outlet
It is between 12 and the length.

(I) b / a ≧ 1 (ii) α ≧ 45 °, preferably α ≧ 90 ° (iii) 2a ≦ c (iv) d / c ≦ 15 (v) At least the same gas as the atomizing gas in the spray chamber 4. Replace with.

The reason why these requirements (i) to (v) are required is as follows.

Requirement (i): When b / a <1, the droplet state of the droplet flow m ₂ formed by the aperture 18 becomes unstable, and the droplet flow m ₂ becomes a flow path.
10 Easily adheres to the inner surface.

Requirement (ii): When α <45 °, the molten metal flow m ₁ must adhere to the continuous surface 21 to form a droplet flow m ₂ due to the viscosity of the molten metal flow m ₁ and the pressure fluctuation during atomization. Will be difficult. If α ≧ 45 °, such a problem can be almost solved. When α ≧ 90 °, the anti-adhesion effect on the molten metal flow m ₁ is perfect.

Requirement (iii): The inner diameter c of the flow channel 10 is preferably larger than the inner diameter a of the throttle 18. When 2a> c, the inner diameter c of the flow channel 10 becomes smaller than the inner diameter of the throttle 18, so that the droplet flow. Due to a slight swing of m ₂ , the droplet flow m ₂ adheres to the inner peripheral surface of the flow channel 10.

When the requirement (iv): d / c> 15, the droplet flow m ₂ adheres to the inner peripheral surface of the flow channel 10 due to the slight fluctuation of the droplet flow m ₂ as described above.

Requirement (v): When the atomizing chamber 4 is replaced with a gas different from the atomizing gas, atomization is caused due to a difference in the viscosity of the both gases until the inside of the atomizing chamber 4 is replaced with the atomizing gas. The chamber 4 becomes very unstable,
This is because nozzle clogging is likely to occur.

When the atomizing gas is He gas, the melting chamber 3 is preferably replaced with Ar gas. This is because if the melting chamber 3 is replaced with He gas as in the spray chamber 4, the thermal conductivity of He gas is too good, and it takes a long time to raise the temperature of the molten metal m, resulting in an extremely low energy efficiency. is there. In this case, since He gas must be recovered for reuse, in order to prevent mixing of Ar gas, a stopper 16 is used before the atomizing chamber 4 and the melting chamber 3 communicate with each other through the melt nozzle 9 in order to prevent atomization. It is necessary to take measures such as closing the inflow port 11 of the melt nozzle 9 or leaving the melt m slightly and ending atomization.

C. Effect of the Invention According to the present invention, the molten metal flow is changed to a droplet flow by adopting an extremely simple means such as providing a restriction in the middle part of the flow path, thereby ensuring nozzle clogging caused by solidification of the molten metal. It is possible to provide a molten metal nozzle that can be avoided.

[Brief description of drawings]

FIG. 1 is an overall front view of a metal powder manufacturing apparatus, FIG. 2 is a longitudinal sectional front view of an essential part of FIG. 1, and FIG. 3 is an enlarged vertical sectional front view of a throttle portion of a molten metal nozzle. m ₁ ... melt flow, m ₂ ... droplet flow, 9 ... melt nozzle, 10 ... flow path,
18 ... Aperture

Claims (2)

[Scope of utility model registration request] 1. A molten metal nozzle used when a metal powder is produced under the application of a gas atomizing method, wherein a molten metal flow (m ₁ ) is applied to an intermediate portion of a vertically extending flow channel (10). A molten metal nozzle for producing a metal powder, characterized in that a diaphragm (18) for dropping in place of (m ₂ ) is provided. 2. The throttle (18) in the high temperature region of the flow path (10).
The molten metal nozzle for producing metal powder according to item (1), wherein