JPS6328805A - Method for preventing sticking of splash to water or gas spraying nozzle - Google Patents

Abstract

PURPOSE:To prevent metal splashes from sticking to a nozzle for spraying high-pressure water, etc., and to efficiently pulverize a molten metal by allowing low pressure water or gas to flow down along the wall surface of said nozzle at the time of blowing the high-pressure water or gaseous flow to the flowing down molten metal and producing the fine particulate powder. CONSTITUTION:The molten metal in a crucible 5 is dropped in the form of molten metal flow 6 from the hole in the bottom of the crucible and the high- pressure water or high-pressure gas from a conduit 2 is ejected from a diagonal downward ejection port 3 of the annular nozzle 1 to the molten metal flow 6 in such a manner that the energy focus 4 thereof aligns to the molten metal flow 6 to pulverize the molten metal to the fine metallic powder 7. A nozzle 8 to eject the low-pressure water or gas is provided above the annular nozzle 1 to allow the water or gas to flow down along the inside wall provided with the ejection port 3 of the nozzle 1. The clogging of the ejection port 3 by the splashes of the molten metal generated at the time of pulverizing the molten metal by the high-pressure water or the like is prevented and the fine metallic powder is produced with the stable operation at a high yield.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a technology for producing fine metal powder by water or gas spraying, and more specifically, to a spray nozzle for generating splash generated during water or gas spraying. This invention relates to a method for preventing the adhesion of.

(Prior art and problems to be solved) There are various methods for producing metal powder, and among them, water spraying and gas spraying are known as methods that can produce fine powder with good properties. It is being

These spraying methods produce a conical water or gas stream by jetting high-pressure water or gas supplied from a conduit 2 to an annular nozzle 1 downward from an ejection hole 3, as shown in Figure 4. In this method, a fine powder 7 is obtained by supplying molten metal 6 from an upper crucible 5 to an energy convergence part 4, which is the apex thereof, and atomizing it.

By the way, in this water spray method and gas spray method, as shown in FIG. 5, the angle θ of the apex 4 of the cone formed by the water or gas flow, the nozzle interval at the base, and the length Q of the oblique side are set to appropriate values. It is important to determine the pressure, velocity, etc. of high-pressure water or gas so that the To increase efficiency, reduce Q and increase the pressure and velocity of high-pressure water or gas to increase the energy at the peak.

On the other hand, the water or gas pressure is 100 kg/cm2 or more, usually 1
It is about 50 kg/cnT, but to obtain finer powder (e.g. I Q μm or less), it is 500 kg/Cod.
It is necessary to make the pressure as high as possible.

However, if the water or gas pressure and speed are increased in an attempt to obtain fine powder with a small particle size, or if the bottom and diagonal angles are decreased, a splash is generated from the energy convergence part at the apex and upward. A scattering phenomenon occurs. This reduces the atomization efficiency and also causes the splash to adhere to the annular inner wall of the nozzle and, in extreme cases, to deposit and block the nozzle nozzle orifice.

(Object of the Invention) The present invention solves the above-mentioned drawbacks of the prior art, effectively prevents the splash generated during water or gas spraying from adhering to the annular inner wall of the nozzle, and efficiently atomizes molten metal. The purpose is to provide the following.

(Structure of the Invention) In order to achieve the above object, the present inventor devised a method to prevent the generated splash from adhering to or accumulating on the annular inner wall of the nozzle even when water or gas is sprayed under conditions that improve the atomization efficiency. As a result of intensive research to find out, if low-pressure water or gas is allowed to flow down along the spray nozzle wall where splash easily adheres, the splash that has already adhered can be easily washed away and splash accumulation on the nozzle wall can be prevented. The present invention was made based on this discovery.

The present invention will be explained in detail below based on examples.

As mentioned above, in order to obtain finer powder with better properties in the water atomization method or the gas atomization method, spraying must be performed under conditions that allow the generation of splash, but in this case,
According to the present invention, adhesion or accumulation of splash can be prevented by simple means, so atomization efficiency can be greatly improved, and water spray or gas spray can be performed stably without clogging the spray nozzle. becomes possible.

(Embodiment) FIG. 1 is a diagram showing an embodiment of the present invention, in which water or gas for preventing splash adhesion is supplied spirally inside a nozzle. In this case, the low pressure nozzle 8 is placed above the spray nozzle 1, and water or gas is sprayed from the nozzle 8 at a spraying water or gas pressure (for example, 200 kg/aI).
The liquid is ejected in a spiral manner at a lower pressure than the above, and is caused to flow down along the annular inner wall surface where the ejection holes 3 of the spray nozzle 1 are provided. The pressure of the water or gas for this purpose is preferably about 20% lower than the pressure of the water or gas for spraying.

It is desirable to use the same type of fluid as water or gas for preventing splash adhesion, just as water is used when spraying water.
There is no problem even in other embodiments.

Although the spraying conditions are the same as those of the conventional method, water spraying or gas spraying can be performed under favorable conditions by employing the above-mentioned means.

FIG. 2 is a diagram showing another embodiment of the present invention, in which water or gas for preventing splash adhesion is caused to flow down from the low-pressure nozzle 9 in parallel along the annular inner wall surface of the spray nozzle 1.

FIG. 3 shows a modification of the embodiment shown in FIG. 2, in which when low-pressure water or gas is made to flow down from the low-pressure nozzle 9 along the inner wall surface, the generated water vapor is smoothly dissipated upward. This is an example in which a spare plate 10 is provided to prevent stagnation. The preliminary plate 1o is preferably as thin as possible in order to allow the low-pressure water or gas to flow down as close to the inner wall surface as possible. Note that it does not necessarily have to extend over the entire surface, and may be provided here and there in the circumferential direction above the nozzle 3).
.

In each of the above embodiments, low-pressure water or gas is supplied in a spiral or vertical manner, but these modes may be combined, or the inner wall surface of the seismic nozzle 1 may be provided at an angle. The design can be changed as appropriate, such as by spraying with

(Effects of the Invention) As detailed above, according to the present invention, it is possible to prevent the splash generated during water spraying or gas spraying from adhering or accumulating on the spray nozzle, so there is no concern about troubles due to splash adhesion. Water atomization or gas atomization can be carried out under favorable conditions without
This can be significantly improved by 30%, and it is also possible to easily produce fine powder of 10 μm or less.

[Brief explanation of drawings]

FIGS. 1 to 3 are explanatory diagrams each showing an embodiment of the present invention, FIG. 4 is an explanatory diagram showing a conventional water spray or gas spray method,
FIG. 5 is an explanatory diagram showing the shape of high-pressure water or gas flow during water spray or gas spray. 1. Water or gas spray nozzle, 2.. Conduit, 3.. Ejection hole, 4.. Energy concentrator for high pressure water or gas flow, 5.
... Crucible, 6. Molten metal, 7. Fine powder, 8.
9. Low pressure nozzle, 10. Spare plate. Patent applicant: Daido Steel Co., Ltd. Patent attorney Hisashi Nakamura Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] A method for preventing splash adhesion to a water or gas spray nozzle, which comprises causing low-pressure water or gas to flow down along the wall surface of the spray nozzle when molten metal is atomized by a high-pressure water or gas stream ejected from the spray nozzle. .