JPS6196015A - Apparatus for manufacturing metal powder - Google Patents

Abstract

PURPOSE:To provide the titled apparatus having simple structure for obtaining fine powder of even particle diameter with high productivity, by adopting the constitution in which molten drops spattered from top end of rotary metal electrode are impinged to a barrier plate of conical curved surface provided at circumference of metal electrode concentrically to divide again said drops. CONSTITUTION:In a vessel 1 of inert gas atmosphere, the metal electrode 3 having a desired component comps. is revolved rapidly at several thousands of revolutions per min, arc is generated between this and nonconsumable electrode 2 opposed thereto, to melt top end part of the electrode 3, and to spatter molten drops by centrifugal force. Together with this, the barrier plate 5 of conical curved surface provided at circumference of the electrode 3 concentrically thereto is revolved at one thousand and several hundreds of revolutions per min by a driving motor 9. In this way, said drops are impinged to inner surface of the plate 5, divided to fine particles by the revolution force, projected to outer part, and solidified to powdery metal particles. The metal powders fall down and are accumulated in a powder collecting vessel 13.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention relates to an improvement of a rotating electrode type metal powder manufacturing apparatus.

(Prior art and problems to be solved) One of the methods for manufacturing metal powder used in powder metallurgy etc. is to rotate a metal rod made of a desired metal at high speed as an anode electrode, and to place a tip of the metal rod facing the anode, such as tungsten, etc. There is a device that melts the tip of a metal rod by sending an arc between it and the tip of a non-consumable electrode, and then scatters the melt using centrifugal force to produce metal powder. The powder must be rotated at a rotation speed of 30,000 to 50,000 revolutions per minute, which is too high for practical use and causes problems such as vibration, and productivity is extremely low. Since the diameters are irregular in size and dispersed over a wide range, there are problems such as a poor yield of powder with a target particle size.

An object of the present invention is to provide a rotating electrode type metal powder manufacturing apparatus that solves the above-mentioned problems.

(Means for Solving Problems) This invention is an apparatus for producing metal powder by arc melting the tip of a rotating metal electrode and scattering the melt by centrifugal force. The present invention relates to a metal powder manufacturing apparatus characterized in that a conical curved surface that collides and re-splits is provided around a metal electrode and concentrically with the electrode.

(Example) Next, embodiments shown in the accompanying drawings will be described.

A non-consumable electrode 2 is provided on one side wall of the container 1 in an airtight manner so that it can be moved in and out. On the other side wall of the container 1 is a rotating device 4.
is provided in an airtight manner, and a metal electrode 3 having a desired composition faces the electrode 2 and is held in such a way that it can be taken in and out of the rotating device 4.

A baffle plate 5 having a conically curved surface is provided concentrically with and around the metal electrode 3, and a cylindrical frame 6 of the baffle plate 5 is supported by a bearing 7 attached to the side wall of the container 1 so as to be rotatable in the L direction.

The baffle plate 5 is designed to be able to retreat as the metal electrode 3 wears out so that the scattering distance of the metal molten droplets is maintained constant. Alternatively, the metal electrode 3 may be fed out as the metal electrode 3 wears out without moving the baffle plate 5. In this case, the distance between the electrodes is kept constant, so there is no need to move the non-consumable electrode 2. Further, it is preferable to attach a liner made of a material such as ceramics to the inner surface of the baffle plate 5, which is not easily attacked by the metal melt, and the surface of the liner can be smooth, uneven, or provided with wings.

A gear 8 is attached to the outside of the cylindrical frame 6, and meshes with a drive gear 10 attached to the rotating shaft of a motor 9 to rotate the cylindrical frame 6 and therefore the baffle plate 5.

An exhaust pipe 11 is attached to the container 1, which is connected to a vacuum pump (not shown), and an air supply pipe 12 is attached to the container 1, which is connected to an inert gas source (not shown).

The bottom of the container 1 is a powder collection container 13 with a gas cutoff device.
This allows the accumulated powder to be taken out at any time.

Since the structure is as described above, the electrode 3 is made of molten metal or sintered metal having a desired chemical composition of metal powder, and the tip of the electrode 3 is positioned in an appropriate layer from the baffle plate 5. Attach it to the rotating device 4 as shown. After the inside of the container 1 is evacuated, an inert gas is passed through the container 1 to create an inert gas atmosphere inside the container.

Next, when the baffle plate 5 is rotated and the cathode non-consumable electrode 2 is brought close to it while rotating at high speed with the electrode 3 as an anode, an arc is generated between the electrodes 3 and 2, and the tip of the electrode 3 is melted. Projected by centrifugal force, the molten droplets collide with the inner surface of the baffle plate 5, are split into fine particles by the rotational force of the baffle plate 5, and are projected outward, solidifying during scattering and falling as metal powder particles. The powder collects in the powder collecting container 13.

In the device of the present invention, the molten droplets are re-split by the rotating baffle plate, so the rotation of the metal electrode 3 only needs to be such that the metal melt collides with the baffle plate by centrifugal force. It is not necessary to rotate at a high speed in the direction of rotation, and the rotation speed is approximately several thousand rotations, and a rotation speed of several hundred rotations is sufficient for the baffle plate.

Large-diameter molten droplets projected from the rotating metal electrode collide with the rotating baffle plate, split, become fine, and scatter again. During re-scattering, the fine particles become spherical due to surface tension, and
It coagulates into a highly pure powder in the absence of oxygen when exposed to an inert gas atmosphere.

(Effects) As described above, according to this device, large molten droplets projected from the metal electrode collide with the baffle plate, re-split, and become fine particles that are scattered. In addition, the fine particles projected from the metal electrode have a small energy when colliding with the baffle plate, and before they collide, they are rapidly cooled and solidified before being projected from the baffle plate, so this device has a particle-regulating effect. The proportion of

In the conventional method, there is a certain relationship between the rotation speed of the metal electrode and the powder particle size, and in order to obtain high-quality spherical fine powder, the rotation speed of the metal electrode must be set at an ultra-high speed of 30,000 to 50,000 revolutions per minute. However, in the device of the present invention, the metal electrode collides with the rotating baffle plate and re-splits, so even if the rotation of the metal electrode is slowed down, powder with uniform fine particles can be obtained with high productivity. Therefore, there are advantages such as the structure of the production equipment is simplified and problems such as vibration are eliminated.

Note that contamination with impurities can be minimized by selecting the material of the liner of the baffle plate and preventing erosion of the liner as much as possible.

[Brief explanation of the drawing]

The accompanying drawing is a central vertical sectional view showing an embodiment of the invention. DESCRIPTION OF SYMBOLS 1... Container, 2... Non-consumable electrode, 3... Metal electrode, 4... Rotating device, 5... Conically curved baffle plate, 6
... Rotating cylindrical frame, 7... Bearing, 8... Gear, 9...
... Motor, 10... Drive gear, 11... Exhaust pipe, 12... Air supply pipe, 13... Powder collection container

Claims (1)

[Claims] In an apparatus for manufacturing metal powder by arc melting the tip of a rotating metal electrode and scattering the melt by centrifugal force, there is provided a cone that collides and re-splits molten droplets scattered from the tip of the rotating metal electrode. A metal powder manufacturing device characterized in that a shaped curved surface is provided around a metal electrode and concentrically with the electrode.