JPH01234506A - Device for producing powder - Google Patents

Abstract

PURPOSE:To suppress mixing with impurities and to increase the purity of produced metal powder by converging ultrasonic waves on a melt obtd. by melting the opposite ends of electrodes with arc between the electrodes to scatter the melt. CONSTITUTION:Arc 52 is generated between a pair of electrodes 51 and the opposite ends of the electrodes 51 are melted with the arc 52. Ultrasonic waves generated from an ultrasonic oscillator 62 are converged on the resulting melt 53 to finely scatter the melt 53. Fine particles formed by the scattering are cooled to obtain powder 55.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a powder manufacturing apparatus for manufacturing metal powder used in powder metallurgy and the like.

[Background Art] Powder metallurgy is a technology for manufacturing metal products or metal ingots by charging metal or alloy powder into a mold, press-molding it, and then sintering the molded body. In powder metallurgy, segregation of component elements does not occur, it is possible to commercialize materials that are difficult to process, it is possible to obtain parts with extremely fine crystal structures, and it is possible to make non-equilibrium phases appear. There are various advantages that cannot be obtained with ingot lumber, such as, and there is also the advantage that secondary cutting can be omitted. For this reason, various powder manufacturing techniques applied to powder metallurgy have been developed.

Among these, the spraying method is widely used because it allows production on an industrial scale and can produce powder with relatively simple equipment.

Typical spraying methods include the argon gas spraying method and the 2M vacuum spraying method. FIG. 2 is a schematic diagram that does not show the argon gas atomization method. In the argon gas atomization method, molten metal 1 stored in a container 2 flows out from a nozzle 3 provided at the bottom of the container 2, and argon gas 4 is sprayed with high energy into the flowing molten metal flow to atomize the molten metal. Powder 5 is obtained by this.

FIG. 3 is a schematic diagram showing the vacuum spraying method. In the vacuum spraying method, a high-pressure gas 15 is blown into the molten metal in a container 12 to make the molten metal 11 supersaturated with gas, and the mixture of molten metal and gas is depressurized through a nozzle 13 by an appropriate exhaust means. Powder 16 is obtained by discharging into vacuum tank 14 and spraying and scattering molten metal 11 under the expansion pressure of scum 15.

A rapid solidification method is a method capable of producing a powder with a fine structure and uniformity on a production scale similar to the gas atomization method and the vacuum atomization method. FIG. 4 is a schematic diagram showing the rapid solidification method. In this rapid solidification method, the high frequency coil 2
By applying a high-frequency current to the molten metal 2, a metal lump is melted in the container 21, and the molten metal 23 that is generated is scattered by the rotation of the tiff 24, which rotates at high speed. Then, this scattered molten metal 23 is rapidly solidified by a cooling medium having high thermal conductivity such as hydrogen gas or helium gas.

Other powder manufacturing methods include a rotating electrode method and a centrifugal granulation method. FIG. 5 is a schematic diagram showing the rotating electrode method. In the rotating electrode method, as shown in FIG. 5, an arc 33 is formed between a consumable electrode 31 and a non-consumable electrode 32, and at this time, the consumable @31 is connected to a rotating means such as a motor (not shown). The powder 35 is obtained by rotating the consumable electrode 31 at high speed and scattering the droplets 34 generated by the melting of the consumable electrode 31.

FIG. 6 is a schematic diagram showing the centrifugal granulation method. In the centrifugal granulation method, a crucible 41 that is rotatably installed in an argon gas atmosphere and an electrode 42 that is installed vertically are formed,
The crucible 41 is rotated while being cooled with water, and droplets 44 formed by melting the electrodes 42 are dropped into the crucible 41, thereby scattering the droplets 44 and producing powder.

[Problems to be Solved by the Invention] However, in the case of the argon gas spraying method, there is a risk that impurities may be mixed in from the container 2 storing the molten metal 1, the nozzle 3, and the spray gas 4. In each case, there is a risk that impurities may be mixed in from the container 21, so there is a problem that it is difficult to produce high-purity powder such as powder for high alloys and superalloys.

In addition, in the rapid solidification method, the falling position of the molten metal stream is concentrated at one point on the rotating disk, so that the disk material is eroded at this position and impurities are mixed in.

In the case of the rotating electrode method and the centrifugal granulation method, there is contamination of impurities from the non-consumable electrode 32 and the crucible 41, respectively, although to a lesser extent than in the case of the above-mentioned methods. Additionally, these methods have a problem in that the production speed is much lower than that of the spray method.

Furthermore, in the case of the conventional rotating electrode method and centrifugal granulation method, it is necessary to water-cool the non-consumable electrode 32 and the rotating crucible 41, respectively, and 50% of the power consumption is taken up by this water-cooled electrode, so the powder Manufacturing efficiency is low and it is extremely disadvantageous in terms of energy economy. Furthermore, in these methods, the consumable electrode 31 made of the alloy to be obtained and the crucible 41, which acts as a water-cooled electrode, need to be rotated at high speed in order to obtain powder with a small particle size. In order to rotate the electrode at high speed, it is extremely difficult to process the electrode and the rotational ellipse.

This invention was made in view of such circumstances, and T.
Pure metals such as i, AI, Cu, alloys thereof, high alloys,
Another object of the present invention is to provide a powder manufacturing device that can efficiently produce high-purity powder that can be used for superalloys at low cost, and that has a mechanically simple device configuration.

[Means and effects for solving the problems] A powder manufacturing apparatus according to the present invention includes a pair of electrodes installed at an appropriate distance, and an arc formed between these electrodes to melt opposing ends of the electrodes. The present invention is characterized by having an arc forming means for causing the melt to flow, and a sound field forming means for concentrating ultrasonic waves on the melt and scattering the ultrasonic waves.

In this invention, an arc is formed between a pair of electrodes, the opposing ends of the electrodes are melted by the arc, and ultrasonic waves are concentrated and act on the melted liquid.
Capillary waves are generated on the surface of the melt, overcome the surface tension, and scatter the melt around. The scattered fine particles of melt are heat exchanged with an inert atmosphere, cooled and solidified into powder.

When applying ultrasonic waves to the melt, there is no problem whether the melt is at the opposite end of the electrode or when it is separated from the electrode and formed into a droplet.

[Example] Hereinafter, the present invention will be specifically described with reference to the accompanying drawings. FIG. 1 shows a powder manufacturing device according to an embodiment of the present invention, and FIG. 1<a) is a longitudinal sectional view of this device.
FIG. 1(b) is a cross-sectional view taken along line BB in FIG. 1(a). The chamber rough is connected to an exhaust means (not shown) such as a vacuum pump through an exhaust port 67, and
A gas inlet 60 is provided, and the inside thereof is maintained under a nitrogen gas, argon gas, or helium gas atmosphere. In the chamber 57, a pair of electrodes 51 having, for example, the same composition as the powder to be manufactured are installed with their longitudinal directions aligned and spaced apart by an appropriate length. A current is supplied to the electrodes 51 from a power source 56, so that an arc 52 is formed between the electrodes 51. This arc 52 melts the opposite ends of the electrodes 51, and the melt falls to form droplets 53.

A pair of resonators 62 arranged below the electrode 51 vibrate the atmospheric scum by the vibration transmitted from the ultrasonic vibrator 64 driven by the ultrasonic power source 65 via the amplitude expander 63. The resonator 62 is provided with a pair of radial direction converters 66 surrounding the resonator 62, and the ultrasonic waves emitted from the resonator 62 are focused on the falling path of the droplet dropping from the tip of the electrode 51. A powerful sound field is created. At this time, the position of the electrode 51 is controlled by the drive device 61 so that the falling path of the droplet does not change as the electrode 51 wears out.

The operation of the powder manufacturing apparatus configured in this way will be explained. First, a power supply 56 supplies power to the electrodes 51 to form an arc 52, and the arc 52 melts the opposing ends between the electrodes, causing them to fall as droplets. On the falling path of the droplet 53, the ultrasonic waves emitted from the resonator 62 are focused to form a strong sound field, so capillary waves are generated on the droplet surface, which is caused by the surface tension of the droplet. Overcome and break the droplets into small pieces and scatter them. The scattered melt of fine particles is solidified and cooled by an inert atmospheric gas to form a powder 55, which is recovered from a powder recovery port 68.

Note that by providing a rotating device that gently rotates the opposing electrodes 51 around their axes in the same direction or in opposite directions, the electrodes 51 are melted uniformly and the arc 5 is
This creates a favorable condition for the formation of 2.

Note that concentrating the ultrasonic waves on the melt before it falls from the opposite end requires the use of the vibrator 64, amplitude expander 63, and resonator 6.
2 and a pair of radiation direction converters 66, the arrangement of the sound field forming device 70 can be easily implemented.

Further, it is also possible to easily continuously charge the electrodes 51 and continuously collect the powder from the powder recovery port 68.

Next, a specific example in which powder was actually manufactured using this example will be described. A Ni-based alloy having the composition shown in Table 1 was used as the material for the electrode.

Table 1 A cylindrical electrode with a diameter of 10n+m was prepared from this Ni-based alloy. These two electrodes were placed facing each other and rotated in opposite directions at a speed of 2 rpm in an Ar gas atmosphere.
A current of 0.00 A was supplied to form an arc between the electrodes.

On the other hand, as a strong sound field source, 120mm x 380m
A duralumin plate measuring m x 5 mm was used as a resonator, and the vibrator was vibrated at 20 kHz. A steel plate was used for the radial direction transducer, and each transducer had a parabolic reflecting surface and was adjusted so that the phase of the sound wave matched in the droplet path in order to efficiently send the sound wave to the droplet falling path. . The sound field forming device 70 was arranged so that the sound field was focused at a position 20 mm directly below each electrode. The strength of the powerful sound field thus achieved is 170 dB.・As described above, the dissolution rate of the electrode is 0.5 kg/min,
A spherical powder with an average particle size of 83 μm was obtained.

[Effects of the Invention] According to the present invention, the crucible, non-consumable electrode, or rotating disk are not touched during the process from arc melting of the electrode to atomization by ultrasonic waves, so there is no risk of impurities being mixed in from these items. High purity metal powder can be obtained.

Furthermore, since consumable electrodes are used for both of the pair of electrodes, a high production rate can be maintained, and since there is no need to water-cool the electrodes, energy efficiency is high and the manufacturing cost of the powder can be reduced. Furthermore, since there is no need to rotate the electrode at high speed, the powder can be obtained using a device with a simple mechanism.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a powder manufacturing apparatus according to an embodiment of the present invention, and FIGS. 2 to 6 are schematic views showing different conventional powder manufacturing apparatuses. 51... Electrode, 52... Arc, 53... Droplet,
55...Powder, 56...Power supply, 57...Chamber,
60... Gas inlet, 61... Drive device, 62...
- Resonator, 63... Amplitude expander, 64... Ultrasonic transducer, 65... Ultrasonic power source, 66... Radiation direction converter, 67... Exhaust port, 68... Powder Collection port, 7o・
...Sound field forming device.

Claims (3)

[Claims] (1) A pair of electrodes installed at an appropriate length interval, an arc forming means for forming an arc between these electrodes to melt the opposing ends of the electrodes, and a means for concentrating ultrasonic waves on the melted liquid. , and a sound field forming means for scattering the powder. (2) The powder manufacturing apparatus according to claim 1, characterized in that the melt leaves the electrode and the ultrasonic waves are concentrated on the melt that has been turned into droplets. (3) The powder manufacturing apparatus according to claim 1, wherein the ultrasonic waves are concentrated on the melt before it leaves the electrode.