JPS6350404A - Spray nozzle for producing metallic powder - Google Patents

Abstract

PURPOSE:To improve the fining and pulverizing efficiency of metallic powder and to uniformize the grain size distribution thereof by disposing twisted guide vanes into a fluid to the passage in such a manner that the high-velocity fluid to be blown to molten metal flow forms an approximately circular conical undivided fluid film. CONSTITUTION:A stopper 27 is pulled up to discharge the molten metal 28 in a tundish 26 down to a spraying nozzle 20 via an outflow nozzle 30. On the other hand, fluid flow 44 is pressfed from a fluid introducing pipe 40 into a storage chamber 38 of the nozzle 30. The fluid flow 44 is given an adequate helix angle alpha by the guide vanes 42 and the fluid flows 44 divided by the guide vanes 42 near the ejection port 34 are joined again by the guide vanes 42 to form the approximately circular conical liquid film which is sprayed in the form of the uniform fluid flow 44 at the spraying angle theta toward the molten metal flow 29. The fining and pulverizing efficiency of the metallic powder is thereby improved and the pulverized grain size distribution is uniformized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a spray nozzle for producing metal powder, which sprays a high-speed fluid such as gas or liquid onto a molten metal stream from the surroundings to obtain metal powder. .

[Background technology]

There is an apparatus that continuously produces metal powder by jetting a high-speed fluid into the molten metal stream from around the flowing molten metal stream. In this manufacturing equipment, the performance of the spray nozzle that ejects high-speed fluid is an extremely important factor because it significantly changes the fineness of the metal powder, the pulverization efficiency, and the particle size distribution of the metal powder.

This spray nozzle has various shapes such as a pencil shape, a V shape, and a conical shape, and FIG. 7 shows a spray pattern by a conical nozzle.

The injection pattern of this conical nozzle is such that molten metal flows down the axial center, and high-speed fluid 1o flows in the direction of the arrow from the annular jet nozzle arranged around the axis, that is, along the conical outline, toward the apex. is ejected into the molten metal stream. Therefore, the high-speed fluid 1o violently collides with the molten metal flow, shearing and crushing the molten metal flow into powder. In order to improve the powdering efficiency of molten metal flow, it is possible to reduce the ratio between the flow rate of molten metal and the flow rate of high-speed fluid per unit time, or to increase the cone angle formed by 1° of high-speed fluid. Effective.

However, since the high-speed fluid collides with the flowing molten metal flow, a portion of the high-speed fluid tends to flow back toward the molten metal flow introduction opening provided in the spray nozzle, making the spray form unstable. When the molten metal is sprayed, the molten metal tends to blow up or accumulate, which causes the inlet for the molten metal flow to become clogged.

In particular, when the high-speed fluid is a gas, unlike a liquid, the high-speed fluid spreads widely near the spray focal point, making it easy to cause a blow-up phenomenon and making it difficult to increase the spray angle.

For this reason, measures such as lowering the atomizing gas pressure and reducing the amount of molten metal flowing down have been taken, but these restrictions on the atomizing conditions reduce the effect of making the metal powder fine and the pulverization efficiency.

In order to improve this, a tangential velocity component is given to the high-speed fluid 10 as shown in the jetting pattern in FIG.
There is also a method in which the fluid film formed by the high-speed fluid 10 is twisted around the molten metal flow to alleviate the collision of the high-speed fluid 10 at the spray focal point and form a stable spray form.

According to this, backflow of the high-speed fluid 10 can be prevented at the spray focal point, and a stable spray state is obtained in which suction force is generated near the spray focal point and the molten metal does not blow up, so that the high-speed fluid 10 is formed. The cone angle can be increased, and the refinement of the metal powder can be improved.

As a means for imparting twist in this way, Japanese Patent Application Laid-open No. 48-
There are those described in No. 20752 and Japanese Patent Application Laid-Open No. 50-67769. When high-pressure fluid is introduced into the annular nozzle, an inlet is provided in the tangential direction on the outer circumference of the spray nozzle to give directionality to the introduced fluid, and a rotating inclined plate is provided inside the spray nozzle. Although the means are shown,
Since the tip of the spray nozzle is narrowly constricted, outflow resistance is high and a sufficient swirling component cannot be imparted to the jetted fluid. Furthermore, in the above case, a constant swirling component is not always given to the flow rate and pressure fluctuations of the fluid passing through the jetting port, so the spray form formed by the jetting fluid is
There is a drawback that the shape approaches the state shown in the figure or changes greatly.

Furthermore, in the method of providing a plurality of grooves on the nozzle body disclosed in this publication, the plurality of grooves provided on the nozzle body are used as jet ports, so the ejected fluid is divided and formed on the circumference of the jet port. Collision between divided flows also occurs on the spray form. Furthermore, the spray form is not formed stably due to fluid flow rate or pressure fluctuations, and since the ejected fluid is divided, the suction effect that occurs near the spray focal point is reduced, making it difficult to manufacture a spray nozzle with a large spray angle. Therefore, a stable spray condition cannot be obtained.

In consideration of the above facts, the present invention aims to provide a spray nozzle for producing metal powder that can significantly improve the fineness of metal powder, the pulverization efficiency, and the distribution of pulverized particle size.

[Summary and operation of the invention]

The present invention provides a spray nozzle for producing metal powder that obtains metal powder by spraying a high-speed fluid onto the molten metal stream from around the molten metal stream flowing down, the spray nozzle having guide vanes twisted around the axis of the metal stream. It is characterized in that it is disposed within a fluid passage and imparts a tangential velocity component to the high-speed fluid ejected from the fluid passage to form an unbroken, substantially conical fluid film.

For this reason, in the present invention, the velocity component in the tangential direction to the jetted fluid jetted from the annular jetting port of the spray nozzle is reliably transmitted by the guide vane provided in the fluid passage immediately before the jetting port inside the spraying nozzle. By making the ejected fluid flow into a uniform annular flow without dividing it, the entire spray form formed always has a twisted flow.

As a result, the spray angle of the spray nozzle can be increased, and a stable spray state can be obtained.

Furthermore, by providing an appropriate twist angle to the guide vanes, a tangential velocity component is reliably imparted to the ejected fluid, and the entire ejected fluid becomes a twisted flow, creating a shearing force that breaks up the molten metal flow. In addition, since it acted uniformly on the molten metal flow, it was possible to achieve improvements in powdering efficiency and fineness of the powder.

In order to make the ejected high-speed fluid flow into a uniform annular flow without breaking up, the tip of the guide vane may be set back from the fluid jet port of the fluid passage, or the tip of the guide vane may be placed at equal intervals around the axis of the metal flow. Effects can also be obtained by arranging a plurality of guide vanes or by tapering the tips of the guide vanes.

[Embodiments of the invention]

FIG. 1 shows a spray nozzle 2o according to this embodiment. In this spray nozzle 20, a molten metal flow introduction port 24 is formed at the axis of a nozzle body 22 with the axis perpendicular to the axis. A tundish 26 is installed coaxially above the molten metal flow introduction port 24, and a molten metal 28, which is molten metal, is accommodated therein. This Tanditshu 2
A molten metal outflow nozzle 30 is formed at the axial center of the molten metal 6 and is arranged coaxially with the molten metal flow introduction port 24 . Therefore, the molten metal 28 in the tundish 26 is configured to flow down into the spray nozzle 20 through the molten metal flow inlet 24 when the stopper 27 is lifted.

In this embodiment, the nozzle body 22 has a central portion, that is, a portion where the molten metal flow introduction port 24 is formed, serving as a nozzle die 32. Inside this nozzle die 32 is a spout 34 (a second
A fluid passage 36 for high-velocity fluid is formed in the radial direction, thereby moving the nozzle die 32 to the nozzle die upper part 3.
2A and a nozzle die lower part 32B.

The fluid passageway 36 has a reservoir chamber 38 at the opposite end of the spout 34 .
The reservoir chamber 38 has a cylindrical shape centered on the axis of the molten metal flow 29, and a fluid introduction pipe 40 is communicated with the reservoir chamber 38. This fluid introduction pipe 40
In this embodiment, a pair of nozzle nozzles are provided, which pass through the nozzle body 22 in the tangential direction of the reservoir chamber 38, and the other end (not shown) is connected to a high pressure fluid supply source.

Nozzle die upper part 32A as shown in detail in Figure 2.3.
A fluid passage 36 formed in a narrow gap between the nozzle die lower part 32B and the nozzle die lower part 32B is communicated with each other by a plurality of guide vanes 42. These guide vanes 42 guide the molten metal flow 29 as shown in FIG.
are arranged at equal intervals around the axis of the
A is in a retracted state from the spout 34 as shown in FIG. Further, the fluid passage 36 in the portion where the guide vane 42 is provided is configured so that the jet port 34 can jet the fluid flow 44 at an angle θ shown in FIG. ing. Therefore, the intersection of the fluid flow 44 and the molten metal flow 29 serves as a spray focal point 46.

As shown in FIG. 3, the guide vane 42 has a tapered tip toward the molten metal flow 29, and has a tapered tip toward the molten metal flow 29.
It has a torsion angle of angle α with respect to a ray extending from the axis of 9. In addition, the guide vane 4 adjacent to the guide cylinder t142
The width of the fluid passage between the outlet 2 and the outlet 2 is tapered toward the ejection port 34. Further, this width may be the same width toward the spout 34. The helix angle α changes depending on the diameter of the molten metal flow introduction port 24 and the size of the spray angle θ. Can take a value. Further, the failure of the guide vane 42 changes depending on the diameter of the molten metal flow introduction port 24.

In this embodiment, the retreat amount C of the tip of the guide vane 42 from the jet nozzle 34 is due to the high-speed fluid that has passed between the guide vanes 42 and been divided, refilling the jet nozzle 34 just before the jet nozzle 34, and creating a uniform flow. The length C is set to an appropriate value to ensure that the specified helix angle obtained when the fluid stream that has become a flowing fluid and is ejected passes through the guide vane 42, and the guide vane 42 is placed on the circumference thereof. shall be arranged with their tips aligned. In this embodiment, dimension C is equal to or greater than A and less than 1/2 of B.

The fourth time is a sectional view taken along the line rV-IV in FIG. 2, and shows a state in which 12 guide vanes 42 are formed around the axis of the molten metal 2*29. However, as shown in FIG. 5, in the cross-sectional view taken along line V-V in FIG. There is no fluid passageway 36, allowing fluid streams 44 to merge again.

When the present embodiment formed in this manner operates, the molten metal 28 in the tundish 26 flows down through the molten metal outflow nozzle 30 by pulling up the stopper 27.

On the other hand, the fluid flow 44 pressure-fed from the fluid introduction pipe 40 to the reservoir chamber 38 is given an appropriate twist angle α by the guide vanes 42, and the fluid flow 44 that had been divided by the guide vanes 42 near the spout 34 is The liquids merge again and become a uniform fluid stream 44 in the absence of partition walls as shown in FIG. 5, which is ejected into the molten metal stream 29 under the spray angle θ.

Therefore, the molten metal a 29 is finely powdered and has a desired average particle size.

Since this fluid flow 44 can apply a suction force to the molten metal flow 29, it is possible to stabilize the molten metal flow 29 and eliminate blowing up.

[Experimental Example 1] Table 1 shows the particle size distribution of Cu alloy powder obtained using the spray nozzle 20 shown in FIG. 1 and a conventional spray nozzle. The spray angles (θ) of the spray nozzles in this experimental example were 700 and 90″, and the torsion angles (α) were 15′″ to 45″, respectively.
' and 25@~50''.The spray angle (θ) of the conventional spray nozzle was set to two types: 50'' and 60@.

In either case, 5 kg of Cu alloy was melted at about 1250° C. using a high frequency melting furnace (not shown) and poured into a tundish 26 which had been heated and maintained at 1100° C. in advance. The poured molten metal is made into a trickle from a molten metal outflow nozzle 30 with a diameter of Φ5 (d) provided at the bottom of the tundish.
The molten metal flow was continuously flowed down into the molten metal flow inlet 24 provided at the center of the spray nozzle 2o. Then, in the molten metal flow 29 flowing down,
Nt gas fluid flow 4 with atomizing gas pressure 9 kg/cnl
4 was ejected and sprayed.

When observing the spray shape* (F-N), it was found that the spray nozzle of the present invention (
In case of (1), molten gold, reduced flow inlet 2
4 There was adhesion of molten metal to the wall surface, and there was a tendency for L2 to slightly blow up, but otherwise it was good.

For conventional nozzles <M, N), the spray angle θ-60 of (M)
'', there was a tendency for some blow-up to occur, but (N
) were in good condition.

It was found that the spray nozzle of this experimental example could obtain a good spray condition even when the spray angle (θ) was wider than the conventional nozzle's 60 inches (70 inches, 906 mm).

In the conventional nozzle (M, N), the spray angle (θ) was set to (N)50
CM)60', the amount of fine powder produced increased, but the particle size distribution still consisted of many coarse powders of 80 mesh or more.

On the other hand, the nozzle (F-L) of this experimental example is similar to the conventional nozzle /l/(
Compared to MSN), there was significantly less coarse powder with a mesh size of 80 mesh or more, and on the contrary, it showed a particle size distribution with more fine powder. moreover,
When the spray angle θ was increased from (1-L) 70" to (F-H) 90°, a particle size distribution with a large amount of fine powder was exhibited. In addition, the spray angle (1-L) 70" and ( F-H) 90
``Even in the nozzle, the particle size distribution of the powder differed depending on the value of the twist angle α.Compared to the conventional nozzle, the nozzle of this experiment showed a particle size distribution with significantly less coarse powder of 80 mesh or more and more fine powder. It was found that the miniaturization efficiency was higher than that of conventional nozzles.

FIG. 6 shows the results of determining the average particle size (particle size value at which the cumulative weight is 50%) of the powder obtained with the nozzle (F-L) of this experimental example.

The helix angle (α) at which the average particle diameter was minimum differed depending on the spray angle θ. In a spray nozzle with a molten metal flow inlet diameter (D) of Φ20, when the spray angle θ is 70'', the minimum particle size is shown when the torsion angle (α) is 306 to 356, and when the spray angle θ is 90, The minimum average particle diameter was obtained when the twist angle (α) was 25″.

In addition, as shown in Table 1, when the twist angle becomes large for both spray angles, that is, (L) of θ=70” and θ=90°.
In (H), the effect of the high-speed fluid colliding with the molten metal flow and pulverizing it was reduced, so there were more coarse grains and the average particle diameter became larger.

In the spray nozzle of this experimental example, as the spray angle (θ) increases, the twist angle (α) that minimizes the average particle diameter of the powder
was found to be smaller, and furthermore, it was found that the fineness of the powder was significantly improved.

[Experimental Example 2] Table 2 shows the spray angle θ-90 which showed the best characteristics of the present invention.
Using a spray nozzle 20 with a helix angle of α-25° at
CIJ alloy metal easily 28 melted at 250℃,
Molten metal outflow nozzle 30 with nozzle diameter (d) Φ3.4.5■-
The atomizing gas pressure is 9 kg/clll N.
The particle size distribution of the resulting powder is shown after atomization with two gas fluid streams 44. As shown in the table, when the diameter of the molten metal outflow nozzle was decreased, coarse particles of 80 mesh or more decreased, and conversely, the particle size distribution showed an increase in fine particles.

In the spray nozzle of this experimental example, the spray gas pressure was 9 kg/
When c+4 is constant, the diameter of the molten metal outflow nozzle 30 (d
) is Φ411 or less (0, P) to adjust the flow rate of the molten metal, and the flow rate ratio (# - flow rate of molten metal during waiting time/spray gas flow rate) is 7 or less, further improving refinement. I found out that I can.

The setting conditions of the spray nozzle in this experimental example are shown below. The fluid passage gap A of the annular zone is 0.5 to 0.75 mm, and the fluid passage length B is 4
．． 9 to 5.7 mm, guide vane tip position C is 0.7 to 1
12 pieces were arranged at equal intervals on the same circumference. The diameter of the nozzle was Φ20 m, and the length E from the bottom surface of the jet nozzle 42 to the tip of the nozzle was Q, 4 mm or more, but as the spray angle became larger, it was better to make E larger.

Note that in the present invention, the high-speed fluid jetted to the molten metal is not limited to a gas flow, but may be a liquid.

〔Effect of the invention〕

As described above, the present invention provides a spray nozzle for producing metal powder that sprays a high-speed fluid onto the molten metal stream from around the molten metal stream flowing down, the spray nozzle being twisted around the axis of the metal stream. This method is characterized by disposing guide vanes in the fluid passage and imparting a tangential velocity component to the high-speed fluid ejected from the fluid passage to form an unbroken approximately conical fluid film. It has the excellent effect of achieving finer grain size, improved powdering efficiency, and uniformity of the desired powdered particle size distribution.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a spray nozzle showing an embodiment of the present invention;
Figure 2 is a partially enlarged view of Figure 1, and Figure 3 is a partial enlarged view of Figure 2.
Fig. 4 is a sectional view taken along the line ■-■ in Fig. 2, Fig. 5 is a sectional view taken along the V-V line in Fig. 2, and Fig. 6 shows the twist angle of the spray nozzle and the average particle diameter of the powder. 7 and 8 are a plan view and a perspective view illustrating the twisting of high-speed fluid in a conventional spray nozzle. 20... Spray nozzle, 22... Nozzle body, 2B... Metal molten metal, 29... Metal molten metal flow, 34... Spout nozzle, 42... Guide vane, 44... Fluid flow.

Claims (5)

[Claims] (1) A spray nozzle for producing metal powder that obtains metal powder by spraying a high-speed fluid onto the molten metal stream from around the molten metal stream, the fluid path being a guide vane twisted around the axis of the molten metal stream. 1. A spray for producing metal powder, characterized in that the spray is disposed within the fluid passageway and imparts a velocity component in a tangential direction to a high-speed fluid ejected from the fluid passage to form an unbroken, substantially conical fluid film. nozzle. (2) The spray nozzle for producing metal powder as set forth in claim (1), wherein the tip of the guide vane is arranged to be retreated from the fluid jet port of the fluid passage. (3) The spray nozzle for producing metal powder according to claim (1), wherein a plurality of the guide vanes are arranged at equal intervals around the axis of the molten metal flow. (4) The spray nozzle for manufacturing metal powder according to claim (1), wherein the guide vane has a tapered tip. (5) The width of the fluid passage between adjacent guide vanes of the plurality of guide vanes is tapered toward the jet nozzle or has an equal width toward the jet nozzle.
3) The spray nozzle for producing metal powder as described in item 3).