KR100800505B1 - Fabricating apparatus for metal powder - Google Patents

Abstract

An apparatus is provided to manufacture fine droplets of the molten metal by vibrating molten metal and manufacture an expected spherical fine metal powder by subjecting the droplets of the molten metal to a refinement process by gas atomization. In an apparatus for manufacturing fine metal powder, comprising a metal melting tank having an orifice formed on the bottom thereof, a vibration transmitting rod for transmitting vibration generated from a vibration generating mechanism to molten metal within the melting tank, a gas heating mechanism and a gas nozzle(120) for ejecting high pressure heated gas from a high pressure gas storage tank to droplets(101) of molten metal discharged from the melting furnace, and a metal powder spray tank(90) for receiving and cooling molten metal droplets sprayed and discharged through a droplet discharge port(70), the apparatus is characterized in that a rotary dispersing member(160) rotated by a motor(161) is installed at the downstream of the droplet discharge port to spray the droplets that has been sprayed and discharged from the droplet discharge port such that the finer droplets are sprayed by colliding the droplets with one another, thereby crushing the droplets into finer droplets, and the gas nozzle is disposed to spray the additionally crushed droplets by slantly ejecting the high pressure gas in the downward direction relative to the dropping direction of the molten metal droplets and colliding the molten metal droplets with one another oppositely to the rotation direction of the rotary dispersing member, thereby additionally crushing the molten metal droplets.

Description

Fabricating apparatus for metal powder

1 is a view schematically showing the configuration of a metal powder manufacturing apparatus according to an embodiment of the present invention.

FIG. 2 is a detailed view illustrating the nozzle structure of FIG. 1.

Figure 3 is a partial cross-sectional view schematically showing the configuration of a metal powder manufacturing apparatus according to another embodiment of the present invention.

Figure 4 is a partial cross-sectional view schematically showing the configuration of a metal powder manufacturing apparatus according to another embodiment of the present invention.

FIG. 5 is a top plan view illustrating an arrangement of the separating member and the gas nozzle of FIG. 4.

6 is a partial cross-sectional view schematically showing the configuration of a metal powder manufacturing apparatus according to another embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

10: Oscilloscope 11: Transformers

12: Function generator 13: Amplifier

14: thermocouple 20: spray gas storage container

30: gas heating device 40: metal device

50: piezoelectric piezoelectric element 51: vibration rod

60: orifice 70: droplet outlet

71, 72: separation outlet 75: separation member

80: gas supply tube 90: powder metal spray tank

110: coolant nozzle 120: gas nozzle

130: inert gas source 140: vacuum pump

150: electrostatic charging ring electrode 151: high voltage power

160: rotational dispersion member 161: motor

The present invention relates to an apparatus for producing metal powder with improved degree of miniaturization of metal powder to be produced.

Conventionally, in the field of producing spherical metal powder, gas atomization, centrifugal atomization, rotary electrode, etc. are used, and powders such as Ni, co, Cu, Au, and Ag are prepared.

In the gas spraying method, a metal powder having a thickness of about 100 μm is produced by a V-type gas nozzle, and the gas nozzle is improved to improve the pulverization efficiency of the molten metal. Spherical metal powder can be prepared. In the centrifugal spraying method, the flow of molten metal is refined to a rotating disk or the like, and in the rotating electrode method, metal droplets are generated by irradiating and melting a beam or the like on an electrode rotating at high speed to produce spherical metal powder.

However, in recent years, there has been an increasing demand for fine spherical metal powder having a size of 20 μm or less, such as fine spherical metal powder used in the electronics industry or spherical metal powder for metal injection molding (MIM). In this respect, however, it has been difficult for the prior art manufacturing methods to match the average particle size to the required level. As a result, the present invention has been made as a result of constant efforts to solve the problems of the prior art.

Regarding the gas spraying method, there is disclosed a method for manufacturing powder of US Pat. No. 6,805,726, and a method and apparatus for preparing a powder made of almost spherical particles of US Pat. No. 7,093,463. A method for producing a shaped metal powder is disclosed.

However, these inventions still have a problem of low fineness or low productivity.

The present invention has been made in view of the above-described state of the art, and an apparatus for producing a desired fine spherical metal powder in a manner of producing droplets of fine molten metal by vibrating the molten metal and miniaturizing the droplets by gas injection. To provide for that purpose.

In order to achieve the above object, the metal powder manufacturing apparatus according to an embodiment of the present invention, a metal dissolution tank having an orifice for dropping discharged molten metal in the lower portion, and the vibration generated from the vibration generating mechanism to the molten metal inside the dissolution tank And a vibrating transmission rod for forming molten metal discharged into the liquid droplets, and a gas for ejecting the high pressure gas heated to the molten metal liquid droplets from the high pressure gas reservoir at a high pressure so that the droplets of the molten metal discharged from the melting tank are further broken and sprayed. An apparatus for producing a fine metal powder comprising a hot air balloon and a gas nozzle, and a metal powder spray tank that receives and cools molten metal droplets that are refined by a high pressure gas and sprayed through a droplet outlet, and sprayed from the droplet outlet. The discharged droplets collide with each other A rotary dispersing member rotated by a motor so as to be chained and sprayed is provided downstream of the droplet outlet, and the gas nozzle ejects the high pressure gas inclined downward with respect to the direction in which the droplet of the molten metal falls. Collision is made to face the direction of rotation of the member so that the droplets of the molten metal is further broken and sprayed.

In this case, the gas nozzle may be composed of a plurality of gas nozzles arranged in an inclined circumferential direction to be sprayed radially outward by colliding with the rotary dispersion member while dropping the droplet from the upstream to the downstream side. In addition, the metal powder manufacturing apparatus according to another embodiment of the present invention, the electrostatic charging means may be installed adjacent to the droplet outlet so that the spray discharged discharged to the electrostatic charge without being agglomerated with each other, the droplet outlet A, it is preferably composed of a separation outlet divided into a separation member so that the liquid droplets are separated into left and right or up and down respectively.

1 is a view schematically showing the overall configuration of a metal powder production apparatus according to the present invention, Figure 2 is a view showing a cross-sectional structure of the nozzle hole for ejecting molten metal droplets of the device of the present invention.

The main feature of the present invention is that fine droplets are produced by vibrating molten metal, and the droplets have a finer structure by gas fractionation. According to the present invention, not only the average particle diameter is 20 µm or less, but also the productivity to yield This improved fine spherical metal powder can be produced.

In the present invention, for example, a container is used to melt the metal. This container can be made of stainless alloy if it is a low melting point metal. However, crucibles using refractory materials are required for metals with high melting point. If a metal such as chromium is highly active with refractory materials, cold containers such as water-cooled copper are used. ) I need a crucible. As the melting means, a heater or the like can be used as long as it is a low melting point metal, and high frequency heating and induction heating are required as long as the metal has a high melting point. Dissolution of the metal can be carried out in a vacuum or in an inert gas such as nitrogen and argon to prevent oxidation of the metal. An orifice for forming a droplet is provided at the bottom of the container, and the number is sufficient as one, but a plurality of orifices may be used to increase productivity.

Since the molten metal has surface tension and cannot fall freely through the small orifice, it is preferable to press the molten metal with an inert gas or the like to form a pressure difference with the recovery box and drop it.

 In addition, a method of vibrating the molten metal may include a method of coupling a rod to a piezoelectric piezoelectric element and vibrating the molten metal as the rod. In the case of using a piezoelectric piezoelectric element, for example, a function generator, a transformer, etc. Vibration may be generated by a vibration generating mechanism consisting of an amplifier and an oscilloscope. In addition, as a means for vibrating other molten metal, it is also possible to generate by an electric vibrator, a pulsed gas flow, an ultrasonic wave and a pulsed magnetic field.

By virtue of vibrating the molten metal, the molten metal flow through the orifice is interrupted into the droplet and changed into the droplet flow due to the effect of vibration and its surface tension. The generated droplet flow is further refined by gas fractionation. As a result, finer droplets are formed into fine spherical powders by the surface tension, and the fine spherical powder is produced by solidifying.

Gas fractionation uses, for example, a gas nozzle in the form of a plepole or a gas nozzle in the form of a compound and can impinge at a spray angle of 10 ° to 35 ° relative to the drop direction of the droplet flow. It is also possible to impinge from the lateral direction of the droplet flow at an angle of 45 ° to 90 ° with respect to the dropping direction. In addition, the system from the lateral direction is preferable because the micronization force acts strongly. In addition, the solidified fine metal powder can be recovered by a recovery box or the like. The recovery box is preferably installed in an inert gas atmosphere such as nitrogen or argon to prevent oxidation of the fine metal powder.

The particle size distribution of the fine metal powder is determined by the viscosity of the molten metal, the droplet size and the spray gas pressure, and the spray gas flow rate, and in particular, depends greatly on the size of the droplet. Therefore, the orifice diameter is preferably 1 mm or less. In addition, when the orifice diameter is too small, the fall of the molten metal is inhibited, so it is preferably 0.01 mm or more. In order to drop the fine droplets from the orifice, the thickness is preferably 0.05-0.5 mm, most preferably 0.07-0.3 mm.

Referring to the drawings will be described a fine metal powder manufacturing apparatus of the present invention.

As shown in FIG. 1, the metal powder manufacturing apparatus of the present invention supplies a droplet manufacturing apparatus A of molten metal, a gas storage tank 20 for storing a high pressure gas for spraying droplets, and a high pressure gas as a molten metal droplet. And a gas supply pipe 80, a gas nozzle 120 mounted at an end thereof, a coolant nozzle 110 mounted at a spray tank, and a metal powder spray tank 90. The high pressure gas of the gas storage container 20 is heated while passing through the heating mechanism 30, the inside of the molten metal dissolution tank 40 and the metal powder spray tank 90 may exhaust the inside by the vacuum pump (13) Inert gas may be filled from the inert gas supply source 130.

The vibration generator for vibrating molten metal includes a piezoelectric piezoelectric element 50 and a function generator 12 for generating a sine wave of a predetermined frequency, an oscilloscope 10 for observing this, and an amplifier 13 for amplifying a sine wave. ) And a transformer 11. The lower portion of the piezoelectric piezoelectric element 50 is mounted with a rod 51, thereby transmitting vibration to the molten metal. Due to this vibration, the molten metal 100 inside the container 40 is blown through the orifice 60 in the lower part of the container 40 to break-up into droplets 101. The droplet 101 may be finely crushed by the gas fraction flowing out through the high pressure gas nozzle 120 to be ejected through the outlet 70 to obtain a fine spherical metal powder 102.

The function generator 12, transformer 11, and amplifier 13 allow the piezo to generate vibrations of 1 to 100 Hz at approximately 300V. This voltage can generate minute distance vibration. This small distance vibration is transmitted to the molten metal 100 by the rod 51. The piezoelectric piezoelectric element 50 needs to be used below the Curie point, and the piezoelectric piezoelectric element can be used by reducing the heat generated from the molten metal by the length of the rod. When the melting point of the molten metal is high, heat may be blocked by a heat insulator or the like.

The material of the vessel of the liquid drop vibrator may be made of stainless steel when producing a metal melting powder having a low melting point. However, refractory materials such as alumina and silica and graphite may be used when manufacturing a metal melting powder having a high melting point. It is good. The rod is made of the same material as the container. Orifice 60 is preferably used to process the sapphire, ruby and the like to form a circular hole in the center inclined. Since the size of the hole affects the size of the droplets, the size is preferably about 1 mm or less.

A heating device may be installed around the vessel 40 of the droplet generating device to dissolve the metal. In the case of a low melting metal, the heating device may be used as a heating heater, but in the case of a metal having a high melting point, an induction heating device and a high frequency heating device may be used. Etc. are required. The temperature of the molten metal is confirmed by the thermocouple 14, it is necessary to adjust the power supplied to the heating device. In addition, it is necessary to install an adjustment system in which the pressure inside the droplet generator and the pressure inside the gas spray tank are set so that the pressure inside the droplet generator is usually high by a pressure measuring instrument. The supply amount can be set by this. In practice, the pressure difference between the droplet generator and the gas spray tank is preferably set at about 0.1 Mpa. In addition, although the pressure inside the tank is considered to be high during gas spraying, this can be countered by installing a gas discharge valve that is opened and closed by pressure.

When performing the operation, the metal material is charged into the container 40 inside the droplet generator, and the rod 51 mounted on the piezoelectric piezoelectric element 50 is adjusted and mounted so as to be directly above the orifice 60. Thereafter, after evacuating the inside of the tank 90 by the vacuum pump 140, the inside of the container 40 is exhausted. After confirming the high vacuum, the metal material is heated to a molten state with a heating device. After confirming the molten state, an inert gas such as Ar or N ₂ is sealed in the container 40, and then the inert gas is similarly sealed in the tank 90. After that, the power of the heating apparatus is increased to increase the temperature of the molten metal to lower the viscosity of the molten metal so that the molten metal easily falls through the orifice. It is preferable to raise the temperature of a molten metal about 100-200 degreeC from melting | fusing point (this confirms with a thermocouple).

Thereafter, the inert gas is further enclosed in the vessel 40 and raised about 0.1 Mpa above the pressure in the tank to cause the molten metal to fall from the orifice by the pressure difference, thereby generating a molten metal flow. Immediately after the flow of the molten metal occurs, the function generator 12, the amplifier 13, the transformer 11, and the oscilloscope 10 generate vibrations in the piezoelectric piezoelectric element, and transmit the vibration to the rod to transfer the molten metal. The droplet flow is formed by vibrating to break the molten metal flow falling from the orifice.

The droplet 101 thus formed is further refined by the gas fractionation supplied from the high pressure gas storage tank 20 and ejected through the gas nozzle 120 to form finer spherical droplets and to form fine spherical metal powder 102 after solidification. ) Will be manufactured. The higher the gas pressure by the high-pressure gas, the better, but the gas spray from the lateral direction having good micronization efficiency can be finely sprayed at a pressure of about 1 MPa. In the case of spraying from the inclined direction, 1 to 3 MPa is required because the micronization efficiency is low. Gas fractionation is sufficiently atomizable if Mach 1.3 or greater. The fine spherical metal powder 102 is scattered to the far side by gas fractionation and collected in the recovery container 95.

In addition, in the present invention, the outlet 70 is composed of two separate outlets 71 and 72 separated from the left and right by the separating member 75 as shown in FIGS. 1 and 2. 72) the angles discharged through each other can be prevented from colliding and agglomerated after spraying, and the flow rate passing through each of the outlets 71 and 72 is reduced by half to separate the outlets 71 and 72. The flow rate can be increased further downstream to increase the flow rate, and thus, droplets can be more finely sprayed from the separation outlets 71 and 72. The inside of each of the discharging outlets 71 and 72 can further have a vortex generating structure or a vortex plate can be attached to further increase the degree of vortex.

In addition, the metal powder manufacturing apparatus according to the present invention, as shown in Figure 3, the electrostatic charging ring electrode 150 is applied to the droplet discharge port 70 as an electrostatic charging means is applied a high-voltage DC voltage from the high-voltage power supply 151 Can be installed adjacently. The droplets discharged by the electrostatic charging ring electrode 150 are charged to the electrostatic charge, so that the repulsive force acts during the spraying, so that they can be prevented from agglomerating with each other, thereby miniaturizing and improving the yield.

In addition, as shown in Figure 4 and 6, the metal powder manufacturing apparatus according to another embodiment of the present invention, the droplets are sprayed and discharged from the droplet outlet 70 collides finer to finely spray and spray A rotary dispersion member 160 rotated by 161 is provided downstream of the droplet outlet 70. In this case, as shown in FIGS. 4 and 5, the gas nozzles 120 are disposed to be inclined in an circumferential direction so as to impinge on the radial dispersion member 160 and spray radially outward while dropping the droplets from the upstream to the downstream side. 6 may be configured as a plurality of gas nozzles 120. Further, as shown in FIG. 6, the high pressure gas is inclined downward with respect to the direction in which the molten metal droplet falls, and the rotary dispersion member 160 is It is preferable that the gas nozzle 120 is disposed so that the droplets of the molten metal are further broken and sprayed by colliding against the direction of rotation.

By using the rotary dispersing member 160 as described above, it is possible not only to be finely crushed by the high pressure gas from the gas nozzle 120, but also to be finely crushed, and in order to form the same droplet, the pressure of the ejected gas is increased. The pressure inside the gas spray tank and the pressure inside the droplet generator can be reduced, thereby providing various advantages.

Reference numeral 170 denotes a centrifugal separator in which fine spherical metal powder is formed through a cooling zone by a cooling solution or a gas or water after the droplets react with the high pressure gas, and is installed to separate the ultrafine particles. Can also be employed.

According to the present invention, the production of fine spherical metal powder having an average particle diameter of 20 μm or less can be stably performed at low cost, and it is possible to realistically provide excellent technology in practical use of metal powder for MIM and metal powder for electronic products. As compared with the related art, it is possible to further refine the yield or to improve the yield, and further, to create a great effect by lowering the working pressure.

Claims (5)

Vibration transfer rod for forming droplets of molten metal discharged by transferring the vibrations generated from the vibration generating mechanism to the molten metal 40 formed in the lower portion of the orifice 60 for the discharge discharged molten metal to the molten metal inside the melting tank (51), a gas heater (30) and a gas nozzle (10) for ejecting the high pressure gas heated to the molten metal droplets from the high pressure gas storage tank (20) at high pressure so as to further break and spray the droplets of the molten metal discharged from the dissolution tank ( In the apparatus for producing a fine metal powder comprising a 120 and a metal powder spray tank (90) for receiving and cooling the molten metal droplet which is refined by the high pressure gas and sprayed through the droplet outlet (70), The rotary dispersion member 160 rotated by the motor 161 is installed downstream of the droplet outlet 70 so that the droplets sprayed and discharged from the droplet outlet 70 collide with each other to be more finely crushed and sprayed. The gas nozzle 120 ejects the high pressure gas inclined downward with respect to the direction in which the droplet of the molten metal falls, and collides against the rotation direction of the rotary dispersing member 160 to further fracture the droplet of the molten metal. Metal powder manufacturing apparatus, characterized in that arranged to spray. The gas nozzles 120 of claim 1, wherein the gas nozzles 120 are disposed to be inclined in an circumferential direction and inclined so as to collide with the rotational dispersion member 160 and spray radially outward while dropping the droplets from the upstream to the downstream side. Metal powder manufacturing apparatus, characterized in that consisting of). delete The metal powder manufacturing apparatus according to claim 1, wherein the electrostatic charging means is installed adjacent to the droplet discharge port (70) so that the sprayed and discharged droplets are charged with the electrostatic charge and do not aggregate with each other. 5. The metal powder according to claim 4, wherein the droplet outlet (70) is composed of separation outlets (71, 72) separated by a separation member (75) to separate the left and right or up and down, respectively, and spray discharge the droplets. Manufacturing equipment.

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