JPH05230508A - Device for continuously feeding consumable electrode rod in rotary electrode-type metal powder producing device - Google Patents

Abstract

PURPOSE:To provide a device for continuously feeding a consumable electrode rod in a rotary electrode-type metal powder producing device without need for the troublesome exchanging operation of the consumable electrode rods, in which the rod is entirely converted into powder and with the safety in the high-speed rotation of the rod improved. CONSTITUTION:A non-consumable electrode and a consumable electrode rod 12 are opposed in a chamber 7, an arc is generated between the opposed ends of the non-consumable electrode and rod 12 to melt the rod 12, and the rod 12 is rotated at a high speed to produce a metal powder. In this rotary electrode-type metal powder producing device, a holding tube capable of piercing the chamber 7, freely moving the rod 12 in its axial direction and integrally rotating the rod 12 around its axis is freely rotatably provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a consumable electrode continuous feed device for a rotary electrode type metal powder producing apparatus which can utilize most of raw materials for powder production in a short time and at low cost.

[0002]

2. Description of the Related Art A rotary electrode type metal powder manufacturing apparatus has been developed as an apparatus for manufacturing spherical powder having high purity. In this device, the raw material of the metal powder to be obtained is used as a consumable electrode rod in a chamber of an inert gas atmosphere, and this is rotated at high speed.
The tip of the consumable electrode rod is irradiated with a plasma arc to locally melt the consumable electrode rod. The melted metal is scattered toward the inner wall of the chamber by the centrifugal force of the consumable electrode rod, but is cooled by an inert gas before reaching the inner wall and solidified into a spherical shape by the surface tension. The powder thus produced is produced without being contacted with water or air as in atomization, so that the purity of the consumable electrode rod before being powdered is high and the purity is high.

In this type of metal powder manufacturing apparatus, there are one that does not have a device for feeding a consumable electrode rod and one that has a device for feeding a consumable electrode rod. The latter one is disclosed in JP-A-60- 70110, Japanese Patent Laid-Open No. 63-176402 and Japanese Patent Publication No. 50-38074. JP-A-60-70110 and JP-A-63-176.
The one indicated by No. 402 is equipped with a high-speed rotation mechanism for gripping the end portion of the consumable electrode rod outside the chamber and rotating the consumable electrode rod so as to move back and forth in the axial direction of the consumable electrode rod. The consumable electrode rod is automatically fed so as to keep a constant distance from the counter electrode while monitoring the potential difference between the electrode rod and the counter electrode.

The one disclosed in Japanese Examined Patent Publication No. 50-38074 is capable of sending the consumable electrode rod from the outside of the chamber as in the case of the conventional example A, and is used by connecting a new consumable electrode rod later. Is what you can do. The consumable electrode rod generally processed in this conventional example has a length of 762
mm, diameter over 25.4 mm, several μm to several thousand μ
It is spun at a speed of about 5000-1500 rpm to obtain a powder in the m range. The outer end side of the consumable electrode rod is supported by a chuck of a high-speed rotation mechanism, and the inner end side of the consumable electrode rod is supported by a dynamic rest in order to prevent whipping motion during rotation of the consumable electrode rod. In addition, an elastic O-ring that directly contacts the consumable electrode rod was used for gas sealing between the chamber and the consumable electrode rod. The O-ring rotates together with the consumable electrode rod, and has a mechanism that does not receive friction with respect to the consumable electrode rod except for the forward movement of the consumable electrode rod in the axial direction.

[0005]

The problem of the rotating electrode type metal powder manufacturing apparatus having no automatic consumable electrode feeder is that the portion of the consumable electrode rod near the chuck for fixing the consumable electrode rod must be left unmelted. Low powder production per consumable electrode, many lots must be melted in order to produce a certain amount of powder, which results in chamber opening, electrode replacement, and chamber vacuum evacuation. Since it is necessary to repeat the introduction of the inert gas into the chamber a number of times, it is time consuming and costly. Further, when heat due to plasma or the like is not efficiently released to the outside from the consumable electrode rod, the temperature rises, which may cause deformation due to softening, unstable rotation, and finally rotation failure.

JP-A-60-70110 and JP-A-63
-When using the consumable electrode automatic feeder shown in No. 176402, by using a long consumable electrode rod with this device, the amount of the consumable electrode rod to be used that remains unmelted is reduced, and the number of times the consumable electrode rod is replaced is reduced. decrease. That is, the above problems can be partially solved. However, in these methods, the consumable electrode rod must be left unmelted near the chuck, and the laborious replacement of the consumable electrode rod is not eliminated. Furthermore, when a long consumable electrode rod is used, stable high-speed rotation operation becomes difficult. This is not only because the length is longer, but also because the length is longer, the deformation of the consumable electrode rod due to the temperature rise has a greater influence on the rotation stability.

In the device of Japanese Examined Patent Publication No. 50-38074, it is not necessary to melt and leave the consumable electrode rod near the chuck as long as the consumable electrode rods are connected to each other later, and it is not necessary to replace the consumable electrode rods with trouble. However, because the above problem is solved, another problem occurs. It is a problem of instability in rotating a consumable consumable electrode rod. Both ends of the consumable electrode rod are held by a dynamic rest and a chuck, but nothing is held between them. For this reason, whipping motion occurs in the middle part of the consumable electrode rod, stable high speed operation cannot be performed, and rotation of 5000 rpm or more is generally not performed. This means that it is not possible to obtain many powders having a small particle size. Therefore, the present invention is
It is an object of the present invention to provide a long-term consumable electrode rod continuous feeding device in a rotating electrode type metal powder manufacturing apparatus, which solves all the problems of replacement work of consumable electrode rod, yield problem, and stability problem of high-speed rotation with a simple configuration. To aim.

[0008]

The technical means taken by the present invention to achieve the above object is to dispose a non-consumable electrode and a consumable electrode rod in a chamber so as to face each other. And a consumable electrode rod, an arc is generated between the opposite ends of the consumable electrode rod to melt the consumable electrode rod, and the consumable electrode rod is rotated at a high speed to produce metal powder. In addition to being inserted into the inside in a penetrating manner, a holding tube that rotatably mounts the consumable electrode rod so that the consumable electrode rod is movable in the axial direction and integrally rotatable around the axial center is rotatably provided.

[0009]

In order to produce the metal powder, an arc is generated between the consumable electrode rod 12 and the non-consumable electrode 2 in FIG. 3 to melt the consumable electrode rod 12, and the holding tube 3 is driven to rotate at high speed. Then, the consumable electrode rod 12 rotates integrally with the holding tube 3, and the molten metal of the consumable electrode rod 12 is scattered by the centrifugal force and cooled, whereby metal powder is produced. At this time, when the length of the consumable electrode rod 12 exposed from the holding tube 3 in the chamber 1 becomes too short to dissolve, the outside of the holding tube 3 outside the chamber 1 is simply Push in using a rod-shaped jig or insert a new consumable electrode rod 12
After that, the consumable electrode rod 12 being melted is pushed out into the chamber 1 to a length such that the consumable electrode rod 12 can be melted again. This opens chamber 1 to
The work of replacing 12 is omitted. Also, consumable electrode rod
All 12 can be changed to powder, and the problem of yield is solved.

Further, when the material of the holding tube 3 is harder, the rigidity of the rotating object is improved, the whipping motion of the consumable electrode rod 12 is suppressed, and the diameter of the rotating object is increased by the thickness of the holding tube 3. Since the size becomes large, the resonance point can be set while avoiding the range of the number of revolutions to be used, and the consumable electrode rod 12 can be stably rotated at a higher speed even when used at a higher speed.
Further, since the consumable electrode rod 12 is covered with the holding tube 3, it is possible to employ a bearing that allows simple and effective support. This is because there is no possibility that foreign matter may adhere to and contaminate the consumable electrode rod 12. By adopting this bearing, high-speed rotation stability can be realized with a more reliable structure. Also, even if the consumable electrode rod 12 is a short consumable electrode rod 12a or a long consumable electrode rod, it can be stably rotated at a high speed. Can be used, which can save the labor of adding the consumable electrode rod.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. In FIGS. 1 and 3, reference numeral 1 denotes a chamber, in which a plasma torch 2 as a non-consumable electrode is airtightly inserted from one side of the chamber 1, and a holding tube 3 is inserted from the other side so as to face the plasma torch 2. There is. Plasma torch 2
Is connected to the negative terminal of the power supply. A powder recovery container 4 is provided below the chamber 1. The inside of the chamber 1 is evacuated at the start of operation and then filled with an inert gas.

In this embodiment, the holding tube 3 has a total length of about 1 m,
It is made of steel with an inner diameter of about 30 mm and an outer diameter of about 50 mm.The tip side is supported by the wall of chamber 1 via bearing 5 so that it can rotate around its axis, and between chamber 1 and holding tube 3. Is kept airtight by the labyrinth inside the bearing 5.
The middle part of chamber 1 is an oil bearing fixed on pedestal 6.
Supported by 7, 8. In addition, the rear part of chamber 1
Output shaft 10 of motor 9 and drive belt fixed on pedestal 6
The motor 9 is connected in an interlocking manner via the holding tube 3
Is driven to rotate about its axis. The motor 9 is connected to an inverter circuit (not shown). Further, the bearing portion is cooled by water obtained from a dedicated hose.

In the holding tube 3, the consumable electrode rod 12 is inserted from the rear end side.
The consumable electrode rod 12 has a tip end side exposed through the holding tube 3 and facing the plasma torch 2. The consumable electrode rod 12 is internally fitted and supported by the holding tube 3 so as to be movable in the axial direction and rotatable integrally with the holding tube 3. A gap of about 5/100 mm in diameter is provided between the inner surface of the holding tube 3 and the surface of the consumable electrode rod 12, and by keeping the gas pressure in the chamber 1 slightly higher than 1 atm, It is designed to suppress the invasion of external gas while suppressing the gas consumption. Further, the consumable electrode rod 12 is connected to the positive terminal of the power supply source.

The consumable electrode rod 12 inserted into the holding tube 3 is constructed by connecting short electrode rods 12a shown in FIG. In this embodiment, the electrode rod 12a has a total length of 200 mm and a diameter of about 30 mm.
The concave portion 13 is formed on one end side, and the protrusion 14 that can be fitted into the concave portion 13 is formed on the other end side.
The apparatus having the above structure was operated on a trial basis in the following manner. The number of revolutions of the motor 9 was gradually increased by the inverter to stabilize the number of revolutions, the plasma torch 2 radiated the plasma arc 15, and the consumable electrode rod 12 was melted. When the exposed portion of the consumable electrode rod 12 inside the chamber 1 becomes shorter, the electrode rod 12a is sequentially fed from the outer end side of the holding tube 3.
Using this method, 8 electrode rods 12a were used in one experiment, and 4 rods were first connected to each other and inserted into the holding tube 3, and the remaining 4 rods were replenished one after the other. It was dissolved and the remaining 4 tubes were left in the holding tube 3. The generated powder 16 is contained in the powder recovery container 4 and is taken out by removing the container 4 from the chamber 1.

The rotation speed was 5000, 8000, 12000 rpm, and the materials of the consumable electrode rod 12 were tested with copper and niobium. As a result, it is possible to obtain a highly pure metallic spherical powder having an oxygen concentration of 10 to 50 ppm, and at 12000 rpm, the average particle diameter is 230
We were able to obtain a very fine metallic spherical powder of μm and copper of 180 μm. It has been proved that it does not impair the original purpose of producing highly pure and fine spherical metal powder.

The stability of high speed rotation will be described. The actual resonance point is 13 for the rotation speed of 5000 to 12000 rpm we use.
There was no problem in use because it was above 000 rpm. Also,
No whipping motion of the holding tube 3 was observed at the above-mentioned rotational speeds used. Fig. 4 shows the results of measuring the resonance point by changing the length of the niobium electrode exposed in the chamber 1. As can be seen from the figure, when the holding tube is not used, the resonance point is 7,000 to 13000 rpm, which overlaps with the rotational speed used for operation. As a result of using the holding tube 3, the resonance point was 13000 rpm or higher, which was higher than the rotational speed used for operation. This proves that the holding tube 3 raises the resonance point. In addition,
By cooling the holding tube 3 from the outside, the consumable electrode rod 12 is cooled by solid conduction and gas conduction, so that the consumable electrode rod 12 is prevented from softening and, as a result, whipping motion is prevented.

Next, the problem of exchanging consumable electrodes will be described. Fig. 5 shows the above-mentioned one experiment, that is, the time required for melting four electrode rods 12a (new in the figure) and the experiment conducted in the past by exchanging four electrode rods of the same length. The time required for (old in the figure) was compared. This data includes chamber opening and other operations. In addition, the work content has become easier, and the burden on the worker has been greatly reduced.

The problem of yield will be described. FIG. 6 shows the ratio of the weight of the generated powder to the weight of the electrode rod used for melting. The value of this experiment (new in the figure) is about 96%, and it is about 96% with the method by the electrode exchange performed in the past (old in the figure).
It was only 65%. The apparatus may be provided with a consumable electrode supply mechanism capable of continuously delivering the consumable electrode rod 12 by the amount of the melted electrode rod 12.

[0019]

According to the present invention, the holding tube is inserted into the chamber in a penetrating manner, and the consumable electrode rod is rotatably movable in the axial direction and is integrally rotatable about the axial center. By providing the consumable electrode rod from the outside of the chamber if the consumable electrode rod is insufficient during melting work, this saves the work of opening the chamber and replacing the consumable electrode rod. Can be changed to powder, and the ratio of the amount of powder produced to the weight of the consumable electrode rod is improved. Moreover, since the consumable electrode rod rotates integrally with the holding tube, the rigidity of the rotating object is improved,
Whipping motion is suppressed, the diameter of the rotating object is increased, and the resonance point of the number of rotations is increased, so that the consumable electrode rod can be rotated at a higher speed and more stably than in the conventional case. It is possible to obtain a small powder of.

Further, even a consumable electrode rod formed by connecting short electrode rods or a long consumable electrode rod can be stably rotated at a high speed, and a consumable electrode rod having an arbitrary length can be produced depending on the amount of powder produced. Can be used. Furthermore, since the consumable electrode rod is covered by the holding tube, there is no possibility that foreign matter may adhere to the consumable electrode rod and contaminate it, and a bearing that enables simple and more effective support of the holding tube can be adopted. The stable structure can improve the stability of high-speed rotation.

[Brief description of drawings]

FIG. 1 is a side sectional view of a main part.

FIG. 2 is a partial side cross-sectional view of an electrode rod forming a consumable electrode rod.

FIG. 3 is an overall schematic view of a rotary electrode type metal powder manufacturing apparatus.

FIG. 4 is a chart showing resonance points measured by changing the lengths of the consumable electrode rod and the holding tube, and calculated values of the resonance point when the consumable electrode rod is the same length and only the consumable electrode rod is used.

FIG. 5 is a chart showing the time required for a consumable electrode dissolution experiment. (New: When a consumable electrode feeder is used, Old: When not used)

FIG. 6 is a chart showing the yield of powder for an electrode rod in a consumable electrode dissolution experiment. (New: When a consumable electrode feeder is used, Old: When not used)

[Explanation of symbols]

 1 chamber 2 plasma torch (non-consumable electrode) 3 holding tube 12 consumable electrode rod

Front page continuation (72) Masao Shimada Inventor Masao Shimada 3-3 2-907 Mikageyamate, Higashinada-ku, Kobe City, Hyogo Prefecture (72) Inventor Isoka Hakurakura 1-4-1 Mikatadai, Nishi-ku, Kobe City, Hyogo Prefecture Shinko Dormitory Room 702 (72) Inventor Rikuro Ogawa 3-12-11 Izumidai, Kita-ku, Kobe-shi, Hyogo (72) Inventor Mitsuki Kakihara 2226, Nishioka, Uozumi-cho, Akashi-shi, Hyogo 21 (72) Inventor Kosaku Ozawa Osaka, Osaka 3-6-35 Higashi-Awaji, Higashiyodogawa-shi, Miyakojima Factory (72) Inventor Shigeshiro Kinoshita 3-6-35 Higashi-Awaji, Higashiyodo, Osaka-shi, Osaka

Claims (2)

[Claims] 1. A non-consumable electrode and a consumable electrode rod are arranged to face each other in a chamber, and an arc is generated between opposing ends of the non-consumable electrode and the consumable electrode rod to melt the consumable electrode rod. In addition, in the rotating electrode type metal powder manufacturing apparatus for manufacturing the metal powder by rotating the consumable electrode rod at a high speed, the consumable electrode rod is inserted in the chamber in a penetrating manner, and the consumable electrode rod is movable in the axial direction and A continuous feed device for consumable electrode rods in a rotary electrode type metal powder manufacturing apparatus, which is provided with a holding tube rotatably fitted and supported so as to be integrally rotatable around an axis. 2. The consumable electrode rod in the rotary electrode type metal powder manufacturing apparatus according to claim 1, wherein the consumable electrode rod fitted in the holding tube is constituted by connecting a plurality of electrode rods. Continuous feeding device.