JPS6022041B2 - Metal particle manufacturing method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates generally to the field of metallurgy, and more particularly to shot, powder, and particle production.

The process of shot beaning typically creates surface compressive stresses in stainless steel materials or in the vicinity of welds to prevent stress corrosion cracking that occurs when the surface is exposed to chloride-containing hot water and subjected to surface tensile stresses. used for

The method is also used for improving fatigue resistance. Manufacturing techniques for stainless steel shot include wire cutting with or without a step to round the edges of the cut. This method is neither cost effective nor capable of producing truly spherical materials. Stainless steel shot was initially produced by cutting drawn wire, and in some cases in the prior art this wire was conditioned to round the edges of the cut. Although this prior art process is cost effective, it does not produce the most desirable spherical shape for shot peening. Metal shot from some metals is produced in a shot tower where the molten metal is cut by a screen and cooled by falling a given distance within the shot tower. Shot has also been produced in the prior art by introducing a stream of molten metal onto a rotating disk that fractures the metal by centrifugal force. Other attempts include U.S. Patent No. 2308; 2341704:
2523454:2567121; 263621
9; 2428718; plaque 91730: and 39515
77.

All of the approaches disclosed in these patents involve the intersection of a fluid stream and a molten metal stream to break the molten metal and produce shot. Powders used in compacting or compaction powder metallurgy are broken up by high pressure water jets or produced in rotating equipment such as those used for some forms of shot.

The methods discussed above do not provide the adaptability and flexibility required by modern technology, nor can such methods readily modify particles.

The method and apparatus embodying the invention provides a cost effective means of producing spherical metal particles with desirable properties such as stainless steel shot for shot beaning. The operation of the device for carrying out the invention is based on the Coanda effect.

The Coanda effect used here is ``even if the wall bends away from the axis of the injection, the direction of movement of the injected gas or liquid approaches the wall contour''.
be limited as follows. A curved surface that generates this Coanda effect will be referred to as a Coanda surface hereinafter.

The present invention provides a process for producing metal particles by breaking the flow of molten metal in droplets and solidifying the droplets, the process comprising steps along a plane that produces the Coanda effect (hereinafter referred to as Coanda plane). A second fluid flowing under the influence of the flow of the first fluid is positioned near the Coanda surface, and the molten metal is applied to the Coanda surface before the first and second fluids intersect with each other. The first fluid and the second fluid flow adjacently and then intersect to cut the molten metal flow into metal particles.

The first and second fluids are preferably each gaseous and the molten metal stream is preferably in the form of a sheet.

The invention also includes an apparatus that makes the method of the invention effective.

The invention therefore also provides an apparatus for carrying out the method of the invention, which apparatus comprises a Coanda surface C delimiting one outer surface of the gas chamber 12, a Coanda surface C defining one outer surface of the gas chamber 12, and a Coanda surface C defining one outer surface of the gas chamber 12, such that the first fluid and the second fluid interact with each other. a slit closure 70 adjacent to the upper end of the Coanda surface C for flowing the first fluid along the surface C;
and a reservoir of molten metal for shaping the flow of molten metal for introduction between the first and second fluids for cutting the molten metal to form metal particles. . In a preferred embodiment, the apparatus of the invention includes a hollow container into which various gases can be forced under pressure.

The container has an arcuate surface on one of its sides forming a Coanda surface. A narrow adjustable slit is provided in the container to allow gas to escape at a selected rate and tangential to the curvature of the curved surface. The slit is dimensioned such that the gas passing therethrough develops a velocity high enough that the gas stream touches and follows a curved surface. (This gas flow is recognized as the initial gas flow.) In doing so, the initial gas flow causes ambient gas to flow with it in a volume several times its volume. When molten metal is introduced from the reservoir into this flow castle, it is trapped between the initial gas flow and the flowing gas flow, and is broken into particles by the force of the gas flow and ejected from the curved surface. The molten metal is kept clear of the curved surface by the initial gas flow, which creates a protective barrier between the molten stream and the surface. Particle size and shape, metal temperature, gas pressure, slit closure, competing media, metal flow shape,
(The flow is formed by the restriction of the opening through which the flow passes.

It can be influenced by adjusting the curved shape (appendages are affected by changes in the profile), the slit position with respect to the curved profile, the orientation of the molten metal flow introduction, or the like. Variation of the initial gas flow and of the surrounding atmosphere gas flowing therewith makes it possible to induce desirable or less desirable properties and surface conditions.

The obvious advantages of the device of the present invention now disclosed over prior art devices are the absence of moving parts and the large protective features associated with the initial gas flow (Coanda surface) which prevent erosion of the curved surface (Coanda surface) by molten metal. (including effects). Depending on the temperature requirements of the various metals, the device may be constructed from high temperature metals, ceramics, alumina components, or the like.

The equipment is continuously cooled by the gas required during the process. In cooling the particles, more spherical particles are created when the particles are solidified in a gaseous atmosphere rather than being forced into a liquid. The entire process is managed in a container that is filled with various gases and forms a large chamber with a reservoir at the bottom to hold the coolant/competent liquid.

Because of the high volume gas flow characteristics of this device, extensive disruption of the molten metal stream is effectively produced by the introduction of relatively large volumes of gas. The particles produced by the process using the present invention are endowed with properties that allow them to be applied in cold molding processes, forging or the like, and also allow for the possibility of uniform molding.

In the production of powders and particles required in powder metallurgy or mold casting, and in the production of gas impingement properties and/or
Alternatively, the possibility of not only surface deformation but also shape and size is enhanced by this process.

The invention will be further explained by way of example with reference to the accompanying drawings, in which: FIG.

Referring to the drawings, shown in FIG. 1 is an apparatus 10 for producing particles of various shapes, sizes, and compositions.

The device 10 includes a top 14, a bottom 16, sides 18 and 20,
and includes a hollow chamber defining the housing 12 including a planar rear wall 22. Furthermore, the housing includes a curved front section 30, best seen in FIG. 2, which includes a working top section having a radius of curvature R2 that mates smoothly and completely with a working bottom section having a radius of curvature R2.

As shown in FIG. 2, the front section 30 forms an S-shaped curve with radii RI and R2 that create opposite bends with R2 being greater than RI. The top portion 32 has an end edge 40 located inside a chamber 42 defined within the housing 12, and the bottom portion 36 has a lower end edge fully connected to the housing bottom 16. As seen in FIG. 2, the arcuate top 32 has an outer surface 50 and the bottom 3.
6 are surfaces 50 and 52 forming continuous arcuate curved surfaces;
and has an outer surface 52.

This surface forms a foil and is hereinafter designated as Coanda surface C, and the shape to create the previously mentioned Coanda effect follows the principles of fluid mechanics and boundary layers known to those skilled in the art. and dimensioned.
The Coanda effect, as well as many of the relevant flow effects utilized in the practice of the present invention, are static as well as fluid properties themselves, such as stagnation pressure, temperature, enthalpy,
It is influenced and governed by the surface properties of the housing, such as the coefficient of friction, dimensions, and the like, as well as the properties of the steel, such as density and the like.

The selection of these parameters will be governed by theories, relationships, formulas, and the like known to those skilled in the fluid mechanics and metallurgical arts. This disclosure will provide instruction to the seasoned technician regarding results, operations, functions, and the like, and these skilled technicians may consult basic textbooks such as: Lib [a Hi of Congress Cata
logCard M. Along with 61-18731, McG is IWingSh published by w-Hill8mk.
Mechanics of Fluids by aner
:Victor L. SUeeter, Uni is i
HandbmkofFluidDy female mlcs compiled by ty of Michigan Press;
ToB. Campbell and B. Day. Jennin Scales, Northwestern University,
McCraw One Day ILI Series mM
Ga by echanicaI EngiMering
s Dynamics; Herman SChli
Cting, UniVe ity. fB
rascal SchWeig, Germany
ated by J. Kestin, Brown Un
iversites, McGraw ill series
in Mechanical Engineering
Depending on the ship's side and the layer 4th edition: Ascher day. S sidepiro, The RoM1d
The Dyna by Press Company
mics and thennodynamlcs
ofCompressible FluidFlo
w, Volume and 2; and the like, Beba or U.S. Patent No. 2052869; 4014487
;3999696;403 group 70;413 Isome and 4
Patents such as No. 147,287: These are other teachings related to details of implementing the invention based on this disclosure. A complete discussion of the considerations required to accurately design a Coanda C is not present in view of the existence of teachings in the above-mentioned textbooks, papers, patents, and the like. The precise design of such surfaces, and the selection of other elements in the fluid to produce particular results, will be within the knowledge of and by those skilled in the pertinent art. It depends on the parameters that become clear from the acquired knowledge. As shown in FIG. 2, the head outer surface 50 is spaced from the housing top 14 to define a gap 60. As shown in FIG. The gap 60 is the top 1
Since 4 is flat, it has a size and shape as determined by the size and shape of surface 50. Therefore, the size and shape of the Coanda surface C is further influenced by the shape and effect of any fluid flow flowing in the gap 60 as is clear from this disclosure. The gap 6 is closed along the side edge by a lip 62 from the top 14 as shown in FIG. Gap 60 thus defines discharge slit 70 and any fluid flowing therein can contact that surface. The location of appendages, separation points, or the like is governed by the shape of surface 50 as well as the flow vector of fluid flowing through gap 160. The gas inlet means includes an inlet conduit 80 attached to the side 18 of the housing and injects fluid into the housing to limit the pressure of the fluid passed to ensure the desired flow through the slit 70 as indicated by arrow GF. fluidly connected to the interior of the housing with a fluid source (not shown) via appropriate valves, fill spaces, gauges, and the like used to regulate the flow of the fluid. Due to the friction between the flow GF and the gas in the periphery surrounding the device 10 and the like, such a flow gradient of the ambient gas is established by the flow GF, as indicated by the arrow EFG.

This flow gradient generally follows the direction of the gas flow GF and then turns around to have a shape that is influenced by the shape of the gas flow GF. The ambient gas is thus about to dissolve into the gas in stream GF, and for this reason can be recognized as a flow zone gas since it dissolves in the gas in stream GF.

The gas in the gradient EFG initially contacts the gas in the flow GF at the vertical axis, which can be seen as region J in FIG. As a result of the shape of the Coanda surface C, the flows GF and E
The FGs are in mirror directions that intersect. Intermingling and mixing occurs later, but it is not prevented. As shown in FIGS. 1 and 2, reservoir 90 includes a reservoir 92 disposed proximate housing 12 and fluidly coupled to a discharge portion 94 thereof.

92 is funnel-shaped in cross-section and a discharge portion 94 is connected to 92 and includes an elongated discharge boat 96 located near the Coanda surface C and the slit 70.
has. Molten metal M is located within reservoir 90 and flows out of discharge boat 96 as indicated by MF in FIG.

Flow MF is sheet-like and in the preferred embodiment is gravity flow. The discharge boat 96 is positioned such that the molten metal is introduced near the Coanda surface C and is at a position J. The molten metal is carried by the gas stream G which starts at position J and follows each other.
Separate F and EFC. The discharge boat is oriented relative to the attitude of the Coanda surface C near location J to draw in molten metal at a corner about the vertical selected to produce the most efficient operation of the device. As mentioned above, the size, shape and location of the discharge boat 96 is such that the flow M
F is chosen such that it is suitably influenced by the flow shown previously to establish the flow pattern shown in FIG. 2 and shown by MC. Appropriate dimensional spaces and flow parameters for the flow MF and discharge boat 96 are determined taking into account the appropriate and desired flow MC;
It is also determined according to the teachings provided by the relevant prior art material. Because the metal in stream MF is denser than the fluid in stream GF, and because of the arrangement of the discharge boats in relation to Coanda surface C, flow GF, influenced by the Coanda surface portion 50 that intersects the metal flow, is The molten metal flow M creates a protective layer of gas GL as shown in Figure 2.
It enters between F and Coanda surface C.

The presence of molten metal flow MC precludes the previously discussed mixing of flows GF and EFG from occurring at or near location J. However, the flow of the three fluids is
Flows GF and EFG intersect until position B is reached by the three streams, adjusted according to normal flow parameters such as pressure, temperature, coefficient of friction and the like as well as the physical properties of the flows and flows. Continuous along the flow path and subsequent mixing of the streams GF and EFG, and in this way mixing of the streams GF and EFG is subsequent but undisturbed. gravity, flow separation effects,
and the like, the fluid flows GF and E
FG is finally mixed in position B. Fluid C
This mixing of F and EFG occurs as a particle stream PF such that the molten metal stream MC breaks into a large number of particles P flowing in a direction and velocity determined by conventional fluid theory. This rupture may occur remotely or gradually depending on flow parameters and the like. However, it is understood that location B may be a zone and the break may be gradual. The distinct delimitations shown in FIG. 2 for locations J and B are not intended to be limiting, as will be understood by those skilled in the art. The whole process consists of a container 10 with a storage chamber (not shown) in it to collect the particles.
Managed within 0.

Container 10 is shown partially removed to show the presence of a suitable storage space underneath device 10. container 100
It is also filled with a suitable gas at a suitable pressure and temperature to establish the desired flow EFG for the ambient gas. The gas within container 100 is ambient gas in such cases. Not only EFG but also fluid flow MF and G
The various shapes and dimensions for the Coanda surface C, pressure and other parameters for F can be selected to ensure the desired particle size and shape for the particles P as well as the production rate of the particles P. Wear.

The pressure, temperature, physical parameters, and other state characteristics and flow-affecting parameters of both fluids as well as the molten metal flow are varied according to known theories to create the desired particles. A complete discussion of such parameter selection and/or for those skilled in the fluid mechanics art to determine such conditions based on the teachings provided by this disclosure is available using standard materials, such as materials related to the above. Since related substances can be investigated, they are not listed here. The process begins by securing the flow GF thereby securing the flow ECG and then the flow MF.

Even though the flow MF is occurring, the riding process of the flow EFG is continuous because it creates the aforementioned frictional effect on the flow sheet of the MF, which friction effect is generated between the flow EFG and the flows MC and EFG. This is because it is the first thing to be established. Even if the direction of the flow gradient field FG is the flow M
Even though C is present, the flows GF and EFG remain oriented because there is a mirror direction that still mixes. The principles previously discussed as well as pseudoflow and fluid moments cause this continuous gradient mixing of flows GF and EFG. Thus,
Once started, the process continues to produce metal particles P. Dedicated hardening means or the like can be provided to transform the particles P into suitable metal particles.

Other means may also be used without departing from the scope of this disclosure. The required quenching is achieved by using a time optimization of the particles P in the surrounding fluid used as a source of the stream EFG.

In summary of this disclosure, the present invention provides an improved direction for forming individual particulate metals from metals using the Coanda effect. Modifications are possible within the scope of this invention.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an apparatus constructed in accordance with one embodiment of the present invention. FIG. 2 is a sectional view taken along line 2-2 in FIG. 1. 10
: device, 12: housing, 14: neck, 16: bottom,
18: side part, 20: side part, 22: plane rear wall, 30: front part, 32: top part, 36: bottom part, 40: end edge,
42: chamber, 50: outer surface, 52: surface, 60: gap, 62: IJ cup, 70: slit, 90: reservoir,
92: Thread, 94: Discharge part, 96: Discharge boat, 10
0: Container. Figure 1 Figure 2

Claims (1)

[Claims] 1. A method for producing metal particles in which a molten metal flow is broken into small droplets and the droplets are solidified, in which a first fluid is caused to flow along a curved surface that generates a Coanda effect, and the flow of the first fluid is A second fluid flowing under the influence is located near a curved surface that generates the Coanda effect, and the Coanda effect is generated between the flow of the first fluid and the flow of the second fluid before they intersect. A method for producing metal particles, characterized in that molten metal is flowed adjacent to a curved surface, and the first fluid and second fluid intersect to break the flow of the molten metal into droplets. 2. The method of claim 1, wherein the first and second fluids are gaseous. 3. A method according to claim 1 or 2, characterized in that the molten metal stream is in the form of a sheet of molten metal. 4. Claims 1 to 3, characterized in that the molten metal flow intersects with the flows of the first and second fluids at a location where the first and second fluids first interact with each other.
The method described in any of the paragraphs. 5 In the metal particle manufacturing device, 1 of the gas chamber 12
A curved surface C that generates a Coanda effect that limits two outer surfaces,
adjacent to the upper edge of the surface C which produces the Coanda effect so as to form a flow of the first fluid along the curved surface C which produces the Coanda effect so that the first fluid influences the second fluid flow intersecting it; a slit opening, and introducing molten metal between the first and second fluids in a fracture manner before the first and second fluids intersect and thereafter intersect to form metal particles; A metal particle manufacturing apparatus characterized by a molten metal reservoir 90 for forming a molten metal flow. 6. A device characterized in that the reservoir 90 comprises an elongated discharge portion 94 for forming the molten metal in the form of a sheet.