JPH02236206A - Method and apparatus for manufacturing spherical fine powder - Google Patents

Abstract

PURPOSE:To obtain spherical fine powder without clogging an injecting hole by making the gas jet injecting quantity injecting parallel with molten metal steam to the specified value at the time of manufacturing the fine powder with atomizing method. CONSTITUTION:The high speed fluid jet is injected from circumference of the flowing-down molten metal steam by using an annular atomizing nozzle 2 and collides against the molten metal stream. By making the gas injection quantity 0.5-1.05 times of sucked gas quantity sucked with injection of only the fluid jet from the annular nozzle in the case of injecting no gas jet, trouble of the clogging of the injecting hole is prevented and the spherical fine powder can be stably manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention utilizes an atomization method in which a high-temperature molten metal material is made to flow down in the form of a rod or plate, and a high-speed fluid jet collides with the molten metal flow to atomize it. The present invention relates to a method and apparatus for obtaining spherical fine powder.

Conventional technology The atomization method, as is well known, is a method in which a molten material such as metal is made to flow down in the form of a rod or plate, and a fluid jet (spray medium) with a jet tip held at a certain angle is sprayed against the molten metal flow to cause the material to collide with the molten metal. In this method, molten metal is atomized and simultaneously cooled to produce a large amount of fine powder such as a single metal or an alloy.

In this atomization method, a method in which a high-speed fluid jet is injected from around a flowing molten metal stream using an annular nozzle to atomize the particles (see Japanese Patent Publication No. 19181/1981) is suitable for producing fine particles. However, the injected fluid or the surrounding fluid attracted by it tends to generate a backflow region with an upward velocity component, and a part of the molten metal material is blown up and adheres to and grows on the annular nozzle, causing the molten metal material to grow. There is a problem in that troubles such as clogging of the flow passage or the injection port of the fluid jet frequently occur.

Another problem is that the generated fine powder mixes with the surrounding fluid attracted by the fluid jet ejected from the annular nozzle, and the surrounding fluid is sucked into the fluid jet and collides with the molten metal flow, resulting in the generated molten metal. One example of this is that the mixed fine powder adheres to the surface of the fine powder and becomes integrated, making it impossible to obtain a spherical fine powder.

In addition, instead of an annular nozzle, many independent injection holes can be used in one
There is a so-called pencil-type atomizing nozzle that is oriented at one focal point, but even with this pencil-type atomizing nozzle, the problem of clogging of the injection hole due to the same blow-up phenomenon occurs, as well as the spherical shape of the atomizing nozzle. There is a problem that fine powder cannot be obtained.

Problems to be Solved by the Invention This invention solves the problem in the method of using an annular atomizing nozzle to inject a high-speed fluid jet into a falling molten metal stream to atomize it. The purpose of this paper is to propose a method and apparatus that can stably produce spherical fine powder by solving the problem of clogging the spherical powder and the inability to obtain spherical powder.

Means for Solving the Problems The gist of the present invention is to inject and collide a high-speed fluid jet against the molten metal flow from around the flowing molten metal flow, and to inject gas from inside the fluid jet in parallel with the molten metal flow. A jet is injected, and the injection amount of this gas jet is
By setting the gas suction amount to 0.5 to 1.05 times the amount of gas that would be induced by injecting only the fluid jet from the annular nozzle when the gas jet is not injected, spherical fine powder is generated and molten metal is blown up. This is a method to prevent the problem of injection hole clogging due to

In addition, by providing a gas jet injection hole in the annular atomizing nozzle body that injects a gas jet from inside the fluid jet injection hole in parallel with the molten metal flow, the spherical fine powder can be stabilized without the problem of injection hole clogging. The equipment is manufactured by

Working: A high-velocity fluid jet is ejected from around a descending stream of molten metal and pulverizes the molten metal by impacting the stream.

A high-speed fluid jet is injected and collided with the molten metal from around the molten metal flow, and a gas jet is injected parallel to the molten metal flow from inside the fluid jet, that is, between the molten metal flow and the fluid jet. This equalizes the pressure in the area surrounded by the fluid jet and the area outside of it, preventing molten metal from blowing up.

The reason why the injection direction of the gas jet that is injected from inside the fluid jet is parallel to the molten metal flow (injection angle of 0 degrees) is because when the injection angle becomes smaller than 0 degrees, the flow of the fluid jet is obstructed, and the average of the generated powder is This is because if the diameter becomes large and the injection angle is larger than 0 degrees, the flow of the molten metal may be blocked and extremely coarse particles may be generated.

The injection amount of the gas jet that is injected parallel to the molten metal flow is
0.5 to 1 of the gas suction amount induced by ejection of only the fluid jet when the gas jet is not ejected
．． The reason for multiplying by 0.05 is that the injection amount of the gas jet is 0.05.
If it is less than 5 times, the pressure in the area surrounded by the fluid jet will be too small compared to the area outside it and blow-up will occur, while if the injection volume of the gas jet is more than 1.05 times, melting will occur. This is because the jet impingement of the fluid jet against the metal stream is hindered, which adversely affects the fine grinding action of the molten metal.

Note that the flow rate of the induced gas for only the fluid jet can be determined as follows.

From FIG. 2, the jig constituting the gas jet injection hole (6) is removed, and with a predetermined flow rate of fluid being injected from the fluid jet injection hole (5), as shown in FIG.
) and the atomizing nozzle (2) to measure the flow velocity, and the induced gas flow rate is determined by multiplying the cross-sectional area of the annular gap by the gas density.

Its general formula is shown below.

W=AXυ×ρ W: Induced gas flow rate <K! J/min) A: Gap cross-sectional area (bottom) υ: Flow velocity (m/s) ρ: Gas density (in/m3) For example, as shown in Figure 5, the atomizing nozzle (2)
Orifice diameter 30. , when the outer diameter of the molten metal pipe (4) is 20 shoes, the cross-sectional area A of the gap is 0.0004 m, the measurement value υ of the hot wire anemometer is 4377 L/s, and the gas density ρ is 1.79 Kg.
/m', the induced gas flow rate can be determined to be 1.8 Ng/min.

As the material to be ejected from the fluid jet injection hole (5) and the gas jet injection hole (6), in addition to inert gas and air, a mixed gas thereof can be used. Also, mixtures of these gases with water and/or low viscosity liquids can also be used.

Furthermore, although the same substance may be ejected from the fluid jet injection hole (5) and the gas jet injection hole (6), different substances may be used. For example, a mixture of water and an inert gas may be used for a fluid jet, and air alone may be used for a gas jet to achieve sufficient effect.

Embodiment FIG. 1 is a schematic view showing an example of an apparatus for producing spherical fine powder according to the present invention, and FIG. 2 is an enlarged vertical sectional front view showing an atomizing nozzle section in the same apparatus.

That is, a seven-ring annular atomizing nozzle (2) is installed above the powder recovery tank (1), and a melting metal container (3) is installed above the atomizing nozzle.

A molten metal container (
A downstream injection opening (4) provided at the bottom of the nozzle 3) is located at the outlet of the nozzle at a predetermined crossing angle with respect to the molten metal stream flowing down through the downstream injection opening (4). Disposed fluid jet injection holes (5) are provided.

The shape of the fluid jet injection hole (5) is not limited in any way, but in addition to an annular slit, a structure in which a large number of independent injection holes are arranged around a downstream injection opening can be used.

(6) is a gas jet injection hole that injects a gas jet in the same direction as the flow direction of the molten metal flow (8) inside the fluid jet injection hole (5), and includes an atomizing nozzle (2).
) located at the top of the main unit.

The appropriate direction of jetting this gas jet is the same direction as the downstream direction of the molten metal flow, that is, vertically downward.

This is because, as shown in Fig. 3, when the injection angle β (see Fig. 4) is smaller than 0 degrees, the average particle size of the produced powder becomes larger;
On the other hand, if the temperature is higher than 0 degrees, the flow of the molten metal becomes unstable and extremely coarse particles are generated.

Table 2 shows the results of producing stainless steel powder by atomizing the stainless steel shown in Table 1 using the above-mentioned apparatus using high-1[argon gas.

For comparison, Table 2 shows cases where the injection conditions of fluid jet and gas jet were changed (Comparative Examples 1 and 2.3),
The case without gas jet injection (conventional method) is also shown.

In addition, the induced gas flow rate due to only the fluid jet was determined by the method described above.1. It was aK9,' minutes.

From Table 2, Comparative Example 1 has a gas jet injection angle of 1
0 degree, coarse particles were generated, and in Comparative Example 2, even though the gas jet was injected parallel to the molten metal flow, the amount of gas jet injection was small, resulting in droplet adhesion and spherical fine powder was obtained. In addition, in the case of Comparative Example 3, coarse particles were generated because the amount of gas jet injected in parallel was too large. In addition, in the case of the conventional method without a gas jet, nozzle clogging occurred and atomization became impossible.

On the other hand, in all the methods of the present invention, spherical fine powder could be stably produced without causing nozzle clogging trouble or coarse particles due to blowing up of molten metal.

Table 1 Below Table 1 Effects of the Invention As explained above, according to the method according to claim 1 and the apparatus according to claim 2 of the present invention, the molten metal flow is sprayed from inside the fluid jet that is jetted against the molten metal flow. The action of the gas jet that is injected in parallel with the molten metal prevents the molten metal from blowing up, prevents the adhesion of droplets, stabilizes the flow of the molten metal, and makes it finer due to the fluid jet.
It is said that spherical fine particles can be stably produced.
This provides excellent effects that cannot be obtained with conventional techniques.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of a manufacturing device for spherical fine powder according to the present invention, FIG. 2 is a longitudinal sectional front view showing an enlarged view of the atomizing nozzle part in the same device, and FIG. 3 is a gas jet injection in the same device. A diagram showing the relationship between the angle and the average particle size of the produced powder, FIG. 4 is a longitudinal sectional front view showing an enlarged view of the gas jet injection nozzle part of the same device as above, and FIG. 5 is a schematic sectional view for determining the induced gas flow rate. . 1...Powder recovery tank 2...Atomize nozzle 3
... Molten metal container 5 ... Fluid jet injection hole 6
...Gas jet injection hole applicant Sumitomo Metal Industries Co., Ltd. agent Patent attorney Yoshihisa Oshida 1i13: ↑Figure 1 Figure 2 Figure 3- Figure 3 Figure 4

Claims (1)

[Scope of Claims] 1. A method of atomizing molten metal by injecting and colliding a high-speed fluid jet with a flowing molten metal stream, wherein a high-speed jet is applied to the molten metal stream from around the flowing molten metal stream. Injecting and colliding a fluid jet, and injecting a gas jet parallel to the molten metal flow from inside the fluid jet, and inducing the injection amount of this gas jet by injecting only the fluid jet when the gas jet is not injected. A method for producing spherical fine powder, characterized in that the amount of gas sucked is 0.5 to 1.05 times the amount of gas sucked. 2. An apparatus for atomizing molten metal by jetting and colliding a high-speed fluid jet with a flowing molten metal stream, comprising an atomizing nozzle body provided with at least one opening for injecting the molten metal stream downward; The atomizing nozzle body includes a fluid jet injection hole that injects and collides a fluid jet from around the molten metal flow flowing down from the opening, and a gas jet from inside the fluid jet injection hole in parallel with the molten metal flow. A device for producing spherical fine powder, characterized in that a gas jet injection hole for ejecting a jet is arranged.