JPS5834525B2 - metal granulation equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the production of high melting point metal powders in the form of fine globules of adjustable size and properties.

A method of obtaining metal powder by a powdering method using a rotating electrode is known.

With this method, a cylindrical or nearly cylindrical rotating electrode made of the alloy to be ground is caused to rotate about its axis.

This axis can be horizontal or vertical.

A thin heating source, e.g. an electric arc, is used at the free end of the electrode (
The other end is fixed and powered).

Centrifugal force forms the molten metal into droplets. This droplet solidifies and cools while traveling along its free path.

Generally, such equipment is placed in an enclosure filled with an atmosphere that is neutral to the metal or in a vacuum enclosure to prevent contamination by powder.

This apparatus makes it possible to obtain powders of highly reactive metals with high melting points, such as alloy steels, nickel alloys, cobalt alloys, titanium alloys, aluminum, niobium, and tungsten alloys.

Known devices using such a method include a heating source fixed in a plane perpendicular to the axis of rotation of the rotating electrode.

Heating takes place along the axis of rotation of the rotating electrode or slightly offset to the outside.

In such an arrangement, the diameter of the rotating electrode is limited to a few centimeters.

For example, if an electrode with a relatively large diameter is heated point-wise, the separation will be localized and the electrode will be carved too locally.

Such diameter limitations bring about the following disadvantages.

In the case of a rational arrangement in which the single rotating electrode mounting device is inside the enclosure, the length of the rotating electrode is determined by the dimensions of the enclosure, but this rotating electrode is relatively light due to its small cross section.

Therefore, the weight of flour obtained from each operation is also very limited.

(The nickel alloy electrode with a diameter of 4CrfL is 10kg per door.
The length of the rotating electrode can be increased if the rotating electrode mounting device (having a mass of ) is outside the enclosure.

Instead, the entire length of the electrode rod must be completely straight, as the leaky seam between the ambient air and the enclosure rubs against the rotating electrode.

Furthermore, the electrode support device must move in such a way that the feeding of the rotating electrode compensates for the wear and tear of the rotating electrode.

The particle size of the obtained powder is determined from the following equation and the characteristics of the rotating electrode.

d = k JE X where d is p hv
” The diameter of the obtained powder grain is in microns, h is the rotational speed of the rotating electrode per minute, R is the radius of the rotating electrode and the diameter is senna meters, and r is the surface tension of the liquid alloy in erg.
/crIL, p is the density of liquid metal and the unit is 9/cut
, is an approximation constant of 165×105.

Thus, to obtain a powder of a given particle size (e.g. 200μ nickel alloy powder), a small diameter electrode requires a rotation speed of 6,000 to 12,000 revolutions per minute, which is an expensive engineering problem to solve. problems (leaky joints, bearings)
I will provide a.

The aim of the invention is to make it possible to obtain powder in reasonably sized enclosures by using rotating electrodes of large diameter that do not require expensive and complex technology.

The apparatus of the invention for this purpose is made of an alloy to be ground and produces metal powder by melting by means of at least one narrow heating source for heating an electrode rotating about its own axis. Apparatus in which a thin heating source moving parallel to the axis of the electrode to compensate for wear of the electrode is also moved in a plane perpendicular to the axis of the rotating cylinder, thus shifting the point of impact of the heating source on the rotating electrode. The rotation of the rotating electrode is also taken into account so that the consumable surface of the metal to be powdered envelops the entire end face of the rotating electrode and advances at a constant speed.

One of the features of the present invention is that when there is only one thin heating source, the heating source moves over a long radius of the end face of the rotating electrode.

One of the features of the invention is that the angle that the ejected powder particles make with the wall is preferably between 10° and 60°, so that the warm particles ejected from the rotating electrode do not stick tightly to the walls of the enclosure. The enclosure in which the device is placed is constructed so that the angle is 45°.

In a first variant of the invention, if the pulverizing enclosure is filled with a gas that is neutral to the metal to be pulverized, the slender heating source device connects the metal to be pulverized and the non-consumable electrode. An electric arc generated between the two or a plasma torch may be used.

The non-consumable electrode or plasma torch is fixed to a vertical axis parallel to the axis of rotation of the rotating electrode and offset relative to this axis by at least half the radius of the rotating electrode.

A non-consumable electrode or plasma torch is constructed by means of an arm that is rotatable and movable so that the electric arc or plasma reaches the center of the consumable surface of the rotating electrode and, after rotation of the axis of the rotating electrode, the edge of the surface. and fixed on the vertical axis.

Movement of the non-consumable electrode or plasma torch parallel to the axis of rotation of the rotating electrode to compensate for wear of the rotating electrode is accomplished by movement of the parallel axis.

In a second variant of the invention, heating can be performed by an electron gun when the powdering enclosure is evacuated.

This electron gun can be fixed, as in the first variant, to an arm fixed on a vertical axis, or it can be fixed simply.

In the latter case, compensation for the wear of the rotating electrode can be achieved by changing the focusing progress of the electron gun.

The movement of the point of impact of the electron flux over the radial direction of the rotating electrode in order to wear the rotating electrode in an orderly manner can be achieved by deflection of the electron flux.

Changing the focus and deflection of the electron flux is performed by conventional electromagnetic devices on the electron gun.

In a third variant of the invention, when the slender heating source device held is an electric arc or plasma torch as before, two non-consumable electrodes are provided for separate power supplies;
Or two plasma torches can be used.

It is also possible to have the two heads of the heating source fixed to one arm which is fixed to one shaft.

These two heads are spaced apart on the same radius of the rotating electrode by a distance between 173 of the diameter of the rotating electrode and the radial length of the rotating electrode, preferably approximately 1/2 of the radial length.

The two heating heads can also be fixed on two separate arms fixed on two separate shafts. This is done in such a way that the entire surface of the front of the rotating electrode is swept without any interference.

In order that the invention may be better understood, two embodiments of the inventive apparatus for producing metal powder will be described below, but the invention is not limited thereto.

In the first embodiment, as in the first variant of the invention described above, the heating means is an electric arc.

FIG. 1 is a longitudinal sectional view of the powdering enclosure of this first embodiment.

A rotating electrode 1 is fixed to a shaft 2 via a handle 3 formed on the rotating electrode.

The mandrel 2 is connected via a drive shaft 4 and a vertical intermediate shaft 5 to 10
It is connected to an electric motor 6 that operates at variable speeds of 00 to 3000 revolutions/rotation.

A bronze disc and graphite friction system 7 allows the shaft 4 to be electrically connected via an electrical cable 8 to a DC generator (not shown).

The rotating electrode 1 is conveyed to a suitable height within the enclosure 13 via a wall cooling sleeve 9.

The rotating electrode 1 is connected to the enclosure 1 in such a way that the container 12 for receiving the powder can be placed in the center of the conical lower part of the enclosure 13.
It is located at a position slightly shifted from the axis of 3.

The enclosure 13 is completely cooled except for a few places where cooling is not possible (portholes, flanges, leaky passages).

The upper part 11 of the enclosure 13 has two round windows 14 which are suitably protected from heat and ultraviolet radiation to aid in the powdering operation.
and 15.

In this upper part of the enclosure 13 there is a ferrule 16 which serves to empty the enclosure before filling it with neutral air with the aid of an orifice 18.
It is connected to an orifice 17 which is connected to a vacuum pump.

An electric arc occurs between the upper surface 19 of the rotating electrode 1 and the non-consumable electrode 20.

Cooling water and electrical current enter through a cooling cable 21 which passes through an electrically insulated leakage passage from the enclosure to the ferrule 16 before being connected to the DC generator via an electrical cable 22. is crossing.

The head of the non-consumable electrode 20 is mechanically connected, but electrically insulated, to the horizontal arm 23 which is connected to the vertical shaft 24.

This vertical axis 24 passes through the leakage passage into the upper part 11 of the enclosure.
A translational or rotational movement can be imparted via two devices 25 and 26 which are placed across the enclosure and placed outside the enclosure.

Such a device with a diameter of about 2.5 m and a height of about 2771 is capable of pulverizing rotating electrodes with a diameter of 100 to 300 mm and a height of between 20 m and 70 cm.

For example, using the apparatus of FIG. 1 with a moving speed at the free end of the heating source of 24 centimeters per second, a 120 mm diameter nickel alloy electrode, and a rotation speed of 3000 rpm, the following particle size distribution was obtained.

〈630μ 98.5% 〈500μ 93.3% 〈315μ 21% 〈250μ 14.7% A second implementation, which is mentioned in this document by way of example and not as a limitation, and is consistent with the third variant mentioned above. In the example, two separate heating heads are provided, the two heads never touching.

FIG. 2 is a plan view of such an embodiment.

The consumable rotating electrode 27 is arranged in two separate arms 30 and 3.
1 and driven in a circular motion.

As a result, the entire front surface of the electrode 27 to be melted is scanned by the two heating heads, which cannot come into contact.

The trajectory of the heating head 28 with respect to the free end surface of the rotating electrode 27 will be described with reference to FIGS. 3a and 3b.

As shown in Fig. 3a, the heating head advances from the edge of the free end surface of the metal electrode toward its center as shown in Fig. 3b, and its radius gradually decreases toward the center as shown in Fig. 3b. A converging spiral shape is created, thereby uniformly melting the free end surface of the rotating electrode.

Variations and modifications in detail are of course possible without departing from the scope of the invention, as well as the use of equivalent methods.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a first embodiment of the device of the present invention, and FIG. 2 is a plan view of a second embodiment of the device of the present invention. Figures 3a and 3b show the locus of movement of the heating head on the free end surface of the rotating electrode. In the figure, 1 and 27 are rotating electrodes, 2 is a shaft, 3 is the axis of rotating electrode 1, 4 is a drive shaft, 6 is a motor, 12 is a container,
13 is a enclosure, 20 is an electrode, 23, 30. 31 indicates an arm, and 28.29 indicates a heating head.

Claims (1)

[Claims] 1. A mounting base for mounting a metal body having a free end face perpendicular to the vertical axis; A morph for rotating this mounting base; A rotation period of the metal body between the center and the edge of the free end face; a heating device for reciprocating at least one heating point with a period smaller than 1; and a heating device that moves the heating point and the free end face parallel to the longitudinal axis of the metal body in order to compensate for wear of the metal body; The rotating metal body and the reciprocating motion of the heating point uniformly melt the free end surface of the metal body, and the molten metal is scattered by centrifugal force and granulated. Features of metal granulation equipment.