JPH0112802B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method and apparatus for producing metal powder using ultrasonic waves.

<Prior Art> It is well known that ultrasonic waves atomize liquid by irradiating it with ultrasonic waves, and it is widely used as a humidifier. It is quite conceivable to apply the same method to liquid metals to obtain fine metal powder, but since liquid metals have much larger density, viscosity, and surface tension values than water, high power is required to atomize them. It is necessary to devise ways to concentrate the ultrasonic waves and their output. Furthermore, it is essential that the vibrating part of the ultrasonic vibrator does not react with molten metal, such as oxides, and must be made of a material that can withstand high temperatures. For example, ceramics can be considered, but if the ultrasonic output is concentrated on the vibrating part, large stress and large displacement will occur, which will eventually destroy it. Therefore, in molten metal at high temperatures, there is a limit to the increase and concentration of ultrasonic output, and it is difficult to atomize a large amount of metal at once. To avoid these difficulties, conventional methods have been to place a small amount of metal on the vibrating surface, melt it, and then irradiate it with ultrasonic waves to pulverize it.

<Problems to be solved by the invention> The conventional method of transferring a small amount of metal material onto an ultrasonic excitation surface, melting it, and activating an oscillator to atomize it and pulverize it is qualitatively inadequate. This is an excellent method as it yields metal powder that is spherical, fine in particle size, and has a narrow particle size distribution.

However, productivity is extremely low because a small amount of metal material is transferred and melted onto the vibrating section each time.

This invention aims to improve the productivity of high-quality metal powder by improving the above-mentioned batch production method to a continuous production method.

<Means for Solving the Problems> In the method of producing metal powder using ultrasonic waves according to the present invention, the excitation part of an ultrasonic oscillator is submerged in molten metal with its excitation surface facing upward, and ultrasonic waves The oscillator and the entire vibrating section are repeatedly moved up and down in this posture to make the vibrating surface appear and disappear from the metal liquid surface, and the vibrating surface scoops the metal out of the liquid and atomizes, scatters, and solidifies. It is characterized by recovering fine metal powder.

Further, the manufacturing device of the present invention includes a metal melting crucible, an ultrasonic oscillator located below the crucible, an ultrasonic oscillator attached to the oscillator, extending upwardly, penetrating the bottom of the crucible, and an upwardly directed excitation surface of the crucible. an excitation rod that has reached near the molten metal liquid level in the oscillator; a vertical drive mechanism that repeatedly moves the supporting member of the oscillator up and down along a guide mechanism so that the excitation surface of the excitation rod repeatedly rises and disappears from the metal liquid surface; The oscillator support member and its vertical drive mechanism are scooped out of the liquid by the vertical adjustment mechanism capable of displacing the metal liquid level height variation range, and the vibration surface of the vibration rod, and are atomized and scattered; It is characterized by being equipped with a collection mechanism for receiving solidified metal fine powder.

<Function> In the metal powder manufacturing method of the present invention, the excitation part of the oscillator that vibrates ultrasonically is submerged in the molten metal liquid, and the upward excitation surface is repeatedly moved up and down so that it appears and disappears from the metal liquid surface. The vibrating surface simultaneously scoops up the molten metal and releases it onto the liquid surface, and atomizes and scatters the molten metal on the liquid surface.

According to the present invention, the conventional steps of placing a small amount of metal on an excitation surface, melting it, and applying ultrasonic vibrations are integrated into the upward movement of an excitation surface that moves up and down.

Further, the metal powder manufacturing apparatus of the present invention melts a large amount of metal in a crucible instead of melting small amounts of metal as in the conventional method. Instead of melting the metal by placing it on the vibrating surface of an ultrasonic oscillator, a vibrating rod that extends upward from the bottom of the crucible is placed in the molten metal, and the vibrating surface at the top of the crucible is repeatedly moved in and out of the metal liquid surface. Just by turning it on, it pumps up molten metal one after another and atomizes it.
The vertical drive mechanism and guide mechanism repeatedly move the oscillator support member up and down, thereby repeating the pumping and atomization.

The oscillator support material and its vertical drive mechanism can be moved up and down together by a vertical adjustment mechanism, and operations such as lowering it as the metal liquid decreases or raising it as metal is added to the crucible can be controlled by The device was designed to be able to perform accurately while continuing to vibrate and reciprocate up and down.

<Embodiment> The figure shows an embodiment of the metal powder manufacturing apparatus of the present invention, in which there is a crucible 2 in an electric furnace 1, in which a metal material to be powdered is melted to form a molten metal 3. It's summery. The crucible 2, the ultrasonic oscillator 4 below it, the excitation rod 5 attached to it, the upward excitation surface 5a at its tip, and the oscillator support 6 are guided by a mechanism 7.
The main parts of this embodiment include a vertical drive mechanism 8 that moves up and down along the same axis, a vertical adjustment mechanism 9, and a recovery mechanism 10 for atomized, scattered, and solidified metal fine powder.

The electric furnace 1 is placed on a refractory base 1a, and a thermocouple 1b
is attached, and the metal material in the crucible 2 is melted by the coil 1c.

The coil 1c is located on the outer periphery of the crucible 2.
There is no problem in making a hole 11 in the bottom and passing the vibration rod 5 through it. The crucible 2 is made of graphite or other materials, and the vibration rod 5 is made of high-grade alumina or the like.
Molten metal 3 without putting a sealant between the two
There is no leakage or interference with vertical movement due to friction.

In this embodiment, the excitation surface 5a at the tip of the excitation rod 5 is made concave to make it easier to scoop up the molten metal 3.
I also try to concentrate the scattering direction directly above as much as possible. The excitation surface 5 is flat, not concave.
There were no problems even when experimenting with a. Specific numerical values of the oscillator 4 and the vibrating rod 5 will be described later.

In this case, the oscillator support member 6 is a horizontal plate, and in order to repeatedly move it up and down, vertical columns 6a are hung from the left and right, and the lower ends of both columns are connected and fixed by a lower horizontal plate 6b. The left and right pillars 6a are restricted by guide mechanisms 7 to only vertically move up and down, and the receiving roll 1 on the lower surface of the lower horizontal plate 6b
When the oscillator 2 is moved up and down by the rotation of the cam of the up-and-down drive mechanism 8, the oscillator 4 is also moved up and down via the column 6a and the support member 6.

The above-mentioned guide mechanism 7 includes a guide column 7a that also serves as a support for the electric furnace 1, and a guide block 7b that moves up and down along the guide column and can be fixed at an appropriate height by tightening the upper and lower screws.
The guide hole of the block 7b guides the vertical support 6b.

In this case, the vertical drive mechanism 8 that rotates the rotary cam is
The vertical adjustment mechanism 9 moves up and down along the left and right vertical rails 9a from the solid line position to the chain line position in the figure. The drive mechanism for raising and lowering is not shown in the drawings because it is well known, but it may be driven by hand or driven by a motor. Oscillator 4 using a rotating cam of the vertical drive mechanism 8
This vertical adjustment mechanism 9 also adjusts the height with respect to the upper and lower oscillator support members 6 so that the vibrating rod excitation surface 5a rises above or sinks below the liquid level of the molten metal 3 due to the vertical movement of the oscillator support member 6. adjust.

In this case, the collection mechanism 10 for the scattered and solidified metal fine powder includes an umbrella-shaped saucer 10a having a hole in the center, and a hood 10b that covers the umbrella-shaped saucer 10a. saucer 10a
The central hole is a metal material supply hole to the crucible 2,
It also serves as a receiving hole through which fine metal powder scatters upward. The fine metal powder that has gone up through this is hood 10.
When it hits b, it scatters in all directions and falls on the saucer 10a. Although not shown in the figure, even if it is scattered, the saucer 10a
It is preferable to provide a plate enclosure or the like so that the metal fine powder that does not enter the crucible 2 can be returned to the crucible 2.

In operation of this device, a metal material is put into the crucible 2 and melted, and the vertical drive mechanism 8 is started to move the oscillator 4 up and down, so that the vibration surface 5a of the vibration rod is moved into the molten metal.
The height is adjusted by the vertical adjustment mechanism 9 so that it repeatedly rises and falls from the liquid level, and then or before that, the power supply circuit 13 of the oscillator 4 is energized. As a result, the process of scooping the molten metal out of the liquid, atomizing it, and dropping the scattered metal fine powder into the recovery mechanism 10 is automatically repeated, and the metal fine powder with excellent particle characteristics can be produced regardless of the manufacturing atmosphere or metal composition. can be manufactured continuously.

Although the oscillator 4 is operated continuously, its output of 30 W does not atomize the molten metal, and when the excitation surface 5a emerges from the metal liquid level, the pumped molten metal is instantaneously atomized.

(Experimental values) A relatively dense Sn-Zn alloy was melted at 260℃. An alumina round rod with a diameter of 8 mm was used as the vibration rod 5 attached to the oscillator. The amount pumped at one time is approximately 2
g, and the rotation speed of the cam of the vertical drive mechanism 8 is
It was set to 60 rpm. The above alloy was atomized by vibrating the vibrating rod 5 using a commercially available ultrasonic oscillator 4 with a frequency of 25 kHz and an output of 30 W. As a result, spherical metal particles with an average particle diameter of 40 μm were obtained at a rate of 90 g/min.

Although one embodiment has been described above, it goes without saying that the method and apparatus for producing metal powder using ultrasonic waves according to the present invention can be varied and applied in a variety of ways according to implementation conditions using techniques well known to those skilled in the art. For example, since the vibrating surface of the vibrating section is submerged upward into the molten metal liquid, the vibrating rod does not necessarily extend from the bottom of the crucible. It is also possible to attach an upwardly facing excitation surface to the lower end of the excitation rod hanging down from above. The shape and area of the excitation surface should also be devised according to the implementation conditions to improve efficiency.

The vertical movement mechanism, vertical adjustment mechanism, etc. of the oscillator can be left to the well-known skills of mechanical engineers.

<Effects of the Invention> This invention succeeded in converting the conventional batch method of producing metal powder using ultrasonic waves to a continuous, mass production method for the first time.

The conventional three-step process of transferring a small amount of metal onto the excitation surface of an ultrasonic oscillator, melting it, and atomizing it by vibration is replaced by this invention, which uses an excitation surface submerged below the metal liquid surface. ,
The process was changed to one where the liquid is poured onto the surface. The result is an extremely simple manufacturing method and device that can continuously produce fine metal powder by simply moving the vibrating surface up and down above the liquid surface.

In addition, the metal powder manufacturing apparatus of the present invention purposely makes a hole in the bottom of the crucible, and the excitation rod attached to the oscillator underneath is erected from this hole into the molten metal in the crucible, which drives the excitation surface up and down. The mechanism can be installed in a large space below the crucible, and the space above the crucible is completely occupied by the metal powder collection mechanism, making it easy for both mechanisms to perform their functions.

In addition, since the oscillator support material and its vertical drive mechanism have a vertical adjustment mechanism that adjusts the height according to the height of the metal liquid level, the oscillator support material and its vertical drive mechanism can be adjusted to changes in the metal liquid level while continuing to pump up and atomize the metal using the vibrating surface. This enabled continuous operation for long periods of time.

[Brief explanation of drawings]

The figure is an explanatory elevational view of one embodiment of this invention. 2... Crucible, 4... Ultrasonic oscillator, 5... Excitation part (rod), 8... Vertical drive mechanism, 9... Vertical adjustment mechanism, 1
0...Recovery mechanism.

Claims (1)

[Claims] 1. Submerging the vibrating part of the ultrasonic oscillator into molten metal with its excitation surface facing upward, causing ultrasonic vibration, and repeating the entire vibration of the oscillator and the vibrating part in this position. Using ultrasonic waves, the vibrating surface is moved up and down to make it appear and disappear from the metal liquid surface, and the fine metal powder that is scooped out of the liquid by the vibrating surface, atomized, scattered, and solidified is recovered. Metal powder manufacturing method. 2. A crucible for melting metal, an ultrasonic oscillator located below this crucible, attached to this oscillator, extending upward, penetrating the bottom of the crucible, and having an upwardly directed excitation surface at the tip near the molten metal liquid level in the crucible. an excitation rod that has reached the desired height, a vertical drive mechanism that repeatedly moves the support material of the oscillator up and down along a guide mechanism so that the excitation surface of the vibration rod repeatedly appears and disappears from the metal liquid surface, and the support material of the oscillator and its top and bottom. a vertical adjustment mechanism capable of displacing the drive mechanism within the range of variation in the height of the metal liquid level, and a collection mechanism that receives fine metal powder that is scooped out of the liquid by the vibration surface of the vibration rod, atomized, scattered, and solidified. An apparatus for producing metal powder using ultrasonic waves, comprising a mechanism.