JPS61246304A - Apparatus for producing metallic powder - Google Patents

Abstract

PURPOSE:To consume uniformly a material to be melted without using the same as a consumable electrode by forming a plasma arc torch facing the material to be melted under rotation at high speed in a hermetic chamber to a non-transfer type so that the top end thereof can be displaced in the direction intersecting orthogonally with the axial center. CONSTITUTION:The inside of the hermetic chamber 1 is maintained under an Ar gaseous atmosphere and the material 7 to be melted is rotated at high speed. Gaseous plasma is supplied to the plasma arc torch 10 and a DC power source superposed with a high frequency is passed from a power source 18 to the torch 10 to operate the same. The top end of the material 7 is thereby melted by which a molten metal is scattered and pulverized powder is formed. The torch 10 constitutes a negative electrode and a water cooling nozzle 15 a positive electrode and therefore there is no need for passing the DC large current to the revolving shaft of a high-speed motor 5 and safety is improved. The displacement of the top end of the torch 10 is made possible by oscillating and adjusting the torch around a spherical body 21 and therefore the uniform melting and consuming of the material 7 are made possible.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a metal powder manufacturing apparatus, and more specifically, the present invention relates to a metal powder manufacturing apparatus, and more specifically, a material to be melted is rotated at high speed while its tip is melted by plasma arc heat, and the molten metal is melted. This relates to a device that produces fine metal powder by scattering it using centrifugal force.
s It is suitable for processing high melting point active metals such as Zr and Nb into powder form.

[Prior art]

Conventionally, the following devices have been used to produce metal powder using arc or plasma heat.

That is, a consumable electrode made of a rod-shaped material to be melted is attached to the rotating shaft of a motor, etc. that rotates at a high speed of 30,000 rpm or more, and the consumable electrode is made to rotate at high speed, and this consumable electrode is used as an electrode. In addition, a tungsten arc electrode or a plasma arc torch with a negative pole is attached on the same axis facing the consumable electrode, and arc discharge or plasma arc is irradiated to the tip of the consumable electrode rotating at high speed. The structure is such that the molten metal is dispersed by centrifugal force and processed into fine metal powder. Further, a tungsten arc electrode or a plasma arc torch is inserted from outside the chamber by the length of the consumable electrode consumed as melting progresses to maintain a constant interval between the tips.

By the way, in such a configuration, the consumable electrode made of the material to be melted becomes the + pole of the arc or plasma arc,
It becomes necessary to flow a large DC current for melting through the rotating shaft of a motor, etc. However, current collection mechanisms such as slip rings that use carbon brushes, which are normal mechanisms for passing current through a rotating shaft,
It cannot be used for high-speed rotations of 30,000 r, p, m or more due to mechanical problems and frictional heat problems. Therefore, the contact between the rotating shaft and its bearing is considered to be a conductive part, but it is not safe. It had many problems due to its nature and was extremely dangerous.

In addition, if the cross-sectional shape of the consumable electrode exceeds the allowable melting range of the arc or plasma arc, the progress of melting at the outer periphery of the cross section will be delayed and the center will melt quickly, resulting in concave shape and uneven wear. This causes motor vibration, and if it progresses further, it may lead to discontinuation of melting. Furthermore, if a tungsten arc electrode is used as the non-consumable electrode, the tungsten will be consumed by the melting heat caused by the arc.
There is also the problem that contamination with manufactured metal powder is unavoidable.

[Purpose of the invention]

The present invention has been made in consideration of the above conventional problems, and by not using the material to be melted as a consumable electrode, the rotating shaft side that rotates the material to be melted at high speed does not need to be used as a conductor. Furthermore, it is an object of the present invention to provide a metal powder manufacturing apparatus that can uniformly consume even if the cross-sectional shape of the material to be melted is somewhat incompatible with the torch, and can further reduce the amount of tungsten mixed in as much as possible. This is the purpose.

[Structure of the invention]

The metal powder manufacturing apparatus of the present invention is provided with a high-speed rotation mechanism that grips a material to be melted in a closed chamber and rotates it around its axis at high speed, and is arranged to face the material to be melted on substantially the same axis as the material and to rotate the material at high speed around its axis. A non-transfer type plasma arc torch is provided which penetrates the sealed chamber so as to be movable in the axial direction, and the tip of the plasma arc torch is configured to be displaceable in a direction perpendicular to the axis. Using a plasma arc torch of It is characterized by being able to be used up.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings. In FIG. 1 showing the entire apparatus, a motor chamber 2 is formed on one side of a closed chamber 1, and an opening 3 formed opposite to the motor chamber 2 is sealed with a lid 4. A high-speed motor 5, which is a high-speed rotation mechanism, is installed in the motor chamber 2, and a rod-shaped material 7 having a circular cross-section is attached to it by a collet chuck 6 provided at the tip of its rotating shaft. The high-speed motor 5 is connected to a motor power source 8 outside the sealed chamber 1 through a circuit 9, and when supplied with power, rotates at 40,000 to 60,000 r, p, m, and rotates the material 7 to be melted. It is configured to rotate at high speed. A non-transfer type plasma arc torch 10 is disposed on the same BB axis as the axis of the material 7 to be melted, so as to face the material 7 to be melted. This non-transfer type plasma arc torch 10 penetrates the lid 4 of the sealed chamber 1 so that it can be moved in the axial direction via a universal seal mechanism 11 and can be angularly displaced so that its tip can be displaced. .

As shown in FIGS. 1 and 2, the plasma arc torch 10 is configured to be water-cooled with cooling water 13, and has a single-pole tungsten electrode 14 disposed inside a copper tube 12. At the tip of the copper tube 12 is a water-cooled nozzle 1 that serves as an electrode.
5 is arranged, and a plasma source gas (mainly A
r gas) is supplied and ejected from the water-cooled nozzle 15, a DC current with a superimposed high frequency is passed from the plasma generation power source 18 between the + and - poles via circuits 19a and 19b, and an arc is created between them. By generating
The water-cooled nozzle 15 is configured to continuously eject high-temperature gas 20 that has been turned into plasma.

The universal seal mechanism 11 is constructed as follows. That is, as shown in FIGS. 1 and 3, the sphere 21
The plasma arc torch 10 is inserted into the insertion hole 22 passing through the
is slidably inserted thereinto, and the inside of the sealed chamber 1 is maintained in a sealed state by an O-ring 23 installed on the inner periphery of the insertion hole 22. The sphere 21 is a packing 24.
The plasma arc torch 10 is fixed to the lid body 4 via a spherical inner surface 26 of a support block 25 which is divided into two parts in the axial direction, and is swingably supported on the spherical inner surface 26 of the support block 25. It is configured to be swingable by an angle θ in the horizontal direction, that is, in the XX direction in FIG. Furthermore, an O-ring 27 installed on the spherical inner surface 26 maintains the airtight state of the airtight chamber 1. The plasma arc torch 10 is connected to a nut member 29 that is screwed onto a feed screw 28, and by rotating the handle 30 to turn the feed screw 28, the plasma arc torch 1
0 in the axial direction to maintain a constant gap with the material to be melted 7, and with such a feeding mechanism, the plasma arc torch 10 is
By swinging the sphere 21 in the XX direction and displacing its tip, the end face of the material 7 to be melted can be uniformly melted and consumed.

In the above configuration, in order to manufacture metal powder, the inside of the sealed chamber 1 is evacuated in advance, and then replaced with Ar gas.
After adjusting the gap between the tip of the material to be melted 7 and the tip of the plasma arc torch 10, the material to be melted 7 is rotated at high speed by the high-speed motor 5 to supply plasma source gas to the plasma arc torch 10 and generate plasma. The plasma arc torch 10 is operated by passing a direct current superimposed with a high frequency from a power source 18. Then, the tip of the material to be melted 7 that is rotating at high speed is melted by the high temperature gas turned into plasma ejected from the water-cooled nozzle 15 of the plasma arc torch 10, and when the molten metal is scattered by the rotational centrifugal force, it becomes fine. Metal powder is formed. that time,
In the plasma arc torch 10, not only the negative pole but also the electrode, which was conventionally made up of a consumable electrode made of the material to be melted, is constructed with a water-cooled nozzle 15 at the tip. Since there is no need to flow a large DC current through the rotating shaft of the high-speed motor 5, the safety of the high-speed rotation mechanism such as the high-speed motor 5 is significantly improved. Furthermore, since plasma arc heat is used as the heat source for melting, the content of tungsten melted into the produced metal powder can be significantly reduced compared to tungsten electrode arc melting. Furthermore, the outer peripheral part of the material to be melted 7 is connected to the plasma arc torch 10.
Even if the allowable melting range is exceeded, the material to be melted 7 can be uniformly melted and consumed by adjusting the swing of the plasma arc torch 10 and displacing its tip.

〔Effect of the invention〕

According to the metal powder manufacturing apparatus of the present invention, since a non-transfer type plasma arc torch is used as described above, an electrode is not required on the side of the material to be melted, and a high-speed rotation mechanism that rotates the material to be melted at high speed is used. There is no need to pass a large DC current through the device, significantly improving safety. Furthermore, since plasma arc heat is used, the content of tungsten in the metal powder can be reduced as much as possible. Furthermore, since the tip of the plasma arc torch is configured to be able to be displaced, it is possible to uniformly melt the outer circumferential portion of the material to be melted, where melting progress tends to be delayed, and vibrations in high-speed rotating parts due to uneven melting. This has the effect of eliminating the occurrence and enabling stable operations.

[Brief explanation of the drawing]

Each figure shows an embodiment of the present invention. Figure 1 is a partial cross-sectional front view showing the overall schematic configuration, Figure 2 is a configuration diagram of a transfer type plasma arc torch, and Figure 3 is an explanatory diagram of a universal seal mechanism. It is. 1 is a closed chamber, 5 is a high-speed motor, 7 is a material to be melted,
10 is a non-transfer type plasma arc torch, and 11 is a universal seal mechanism.

Claims (1)

[Claims] 1. A high-speed rotation mechanism is provided in a sealed chamber to grip the material to be melted and rotate it at high speed around its axis, and the mechanism is arranged to face the material to be melted on substantially the same axis and to be movable in the direction of its axis. A metal powder manufacturing apparatus characterized in that a non-transfer type plasma arc torch is provided that penetrates a closed chamber, and the tip of the plasma arc torch is disposed so that it can be displaced in a direction perpendicular to the axis.