JPH02236207A - Apparatus for manufacture metal powder - Google Patents

Abstract

PURPOSE:To recover metal powder at good yield by arranging a cylindrical part at lower part of an atomizing medium injection nozzle in apparatus, where liquid atomizing medium is injected to produce the metal powder, and arranging gas-liquid separating vessel, which spirally rotates and charges slurry flowing down through the cylindrical part. CONSTITUTION:At the lower part of the liquid atomizing medium injection nozzle 2 in the apparatus, where the liquid atomizing medium is injected to the molten metal stream to manufacture the metal powder, the cylindrical part 10 having length enough to solidify the metal fine particles manufactured with the injection is arranged. This cylindrical part 10 is constituted of a straight tube part 10a and a bending tube part 10b, by which the flowing-down slurry is rotated and charged into the gas-liquid separating vessel. By this method, the recovery ratio of the product can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a metal powder manufacturing apparatus used for manufacturing sintered mechanical parts by a powder metallurgy method.

<Prior art> The atomization method, in which metal powder is produced by directly exposing, crushing, cooling, and solidifying a molten metal stream using a spraying medium, generally involves a process in which the molten metal stream flows downward, as shown in Figure 4. It consists of a temporary reservoir (tundish) 1 for the molten metal flow, a spray nozzle 2, a spray tank 3, a post-treatment process, etc. 4 is a melting furnace.

The purpose of this dew tank 3 is the following two items.

(2) Collecting the mixed flow of the produced powder and the spray medium jet.

■To prevent an increase in the amount of oxygen in the powder, replace the atmosphere with an inert gas.

In order to achieve such an objective, a method has conventionally been adopted in which a spray nozzle 2 is generally installed inside a cylindrical tank 3 as shown in FIG. Spray nozzle 2 in tank 3
When installing a tank 3, it is common to first accumulate a certain amount of spray medium in the tank 3 and then start spraying. in this case,
The spray medium jet 5 falls and collides with the spray medium accumulated in the spray tank 3 at a high speed of 50 m/sec or more with accompanying airflow. For this reason, the spray medium stored in the tank vibrates violently, and in severe cases, waves of the spray medium directly contact the spray medium jet 5 and impede spraying. Further, this rocking may generate an airflow in the spraying tank 3 and periodically fluctuate the airflow near the spraying medium jet 5. In such cases, the particle size distribution of the powder expands and the product yield decreases.

Problems to be Solved by the Invention There are many proposals for preventing the adverse effects of the swinging of the slurry in the spray tube 3, but these methods involve installing a prevention plate or the like that prevents the movement of the slurry. Basically, it is difficult to prevent airflow from occurring within the jet tank.

For example, in the spray tank 3 shown in FIG.
There is a device in which a wave-dissipating structure 8 is provided at the lower layer of the spray part 7 where the spray medium collides, but the turbulence of the airflow directly under the spray medium jet 5 cannot be prevented, and the effect is not sufficient (for example, JP-A-57 −
(See Publication No. 94506).

Furthermore, when such prevention plates are used to produce metal powder of several micrometers as disclosed in JP-A No. 60-152605, the metal powder adheres to these plates and becomes difficult to recover. In addition, there is the problem of mixing different brands, which is not desirable.

Further, if the cylindrical guide 9 disclosed in Japanese Patent Publication No. 52-49784 shown in FIG. 6 is used, it is possible to reduce the influence of disturbance of the spray medium in the spray tank 3, but Similar to JP-A No. 57-94506, the problem of adhesion and accumulation of metal powder on the inner wall surface, bottom surface, etc. of the spray tube 3 cannot be avoided.
Such a problem regarding recovery of metal powder from the spray tank 3 also occurs in a general spray tank shape as shown in FIG. 4.

To solve this problem, Japanese Patent Laid-Open No. 61-2641 shown in FIG.
The apparatus disclosed in Japanese Patent No. 07 discloses that the slurry in the spray tank 3 is stirred to be uniform and continuously dehydrated.

Although this method can reduce the adhesion of metal powder compared to the conventional method, it is difficult to avoid the above-mentioned problem caused by disturbance of the spray medium in the spray tank 3.

The present invention is an apparatus for manufacturing metal powder by injecting and colliding a liquid spray medium such as water into a molten metal flow, and the present invention is characterized by the swinging of the spray medium in the spray tank where spraying of the spray medium was conventionally performed. The purpose of the present invention is to provide a metal powder manufacturing device that can prevent the destabilization of the spouting caused by such factors, and can recover the resulting fine metal powder in a high yield without adhering to or depositing on the walls, bottom, etc. of the device. It is said that

Means for Solving the Problems> As a result of intensive study by the inventors on means for solving the problems of the above-mentioned prior art, the inventors basically found that: Avoid accumulating slurry.

■We have found that it is effective to separate the spray section and slurry storage section.

That is, according to the present invention, in order to achieve the above object,
In an apparatus for producing metal powder by injecting a liquid spraying medium into a molten metal flow, a nozzle that injects the liquid spraying medium has a length at the lower part of the nozzle that is capable of solidifying metal fine particles generated by spraying the liquid spraying medium. There is provided a metal powder manufacturing apparatus characterized by having a gas-liquid separation tank having a section, through which slurry flowing down is rotated and charged in a spiral manner.

It is preferable that the cylindrical part comprises a straight pipe part and a curved pipe part for rotating the flowing slurry in a spiral shape and charging it into the gas-liquid separation tank.

Moreover, it is preferable that the gas-liquid separation tank has a deflection plate for rotating the slurry in a spiral shape.

Further, it is preferable that the lower outer periphery of the nozzle that injects the liquid spraying medium has a sealing structure, and that the nozzle has an inert gas supply port in the upper part.

The present invention will be explained in more detail below based on an embodiment shown in FIGS. 1 and 2.

The metal powder manufacturing apparatus of the present invention includes a tundish 1 having a hole at the bottom for storing molten metal 6 and flowing it downward, and a tundish 1 located at the lower part of the tundish 1 that sprays the molten metal 6 flowing down from the tundish 1. A spray nozzle 2 for injecting a medium jet, a cylindrical tube 10 extending from the lower part of the spray nozzle 2, a gas-liquid separation tank 11 connected to the lower end of the cylindrical portion 1o, and the gas-liquid separation I ! A dehydrator 12 is provided at the bottom of the gas-liquid separation tank 11 to dehydrate the slurry discharged from the waste slurry lo Ila provided at the bottom of the tank 11.

The above-mentioned section 10 is composed of a straight pipe section 10a on the side of the spray nozzle 2 and a curved pipe section 10b following this, and the molten metal 6 stream flowing down from the hole provided at the bottom of the tundish 1 is
The particles are atomized by a high-speed spray medium jet in the straight pipe section 10a at the bottom of the spray nozzle 2, solidify while descending the cylindrical section 1o, and are discharged together with the atmosphere from the curved pipe section 10b.

In this way, by creating an elongated sealed path between the injection portion of the molten metal flow 6 and the outlet side of the curved pipe portion 10b, the effects of changes in air flow, etc. are eliminated. As a result, the turbulence of the airflow in the spray area due to the swinging of the slurry in the N spray tank, which has been a problem in the past, has no effect at all if the cylindrical portion 10 is set to an appropriate length.

Roughly speaking, the slurry jet accompanied by the airflow that descended through the straight pipe section 10a is deflected from the vertical direction to the horizontal direction by the curved pipe section 10b, and then rotates and descends along the wall surface within the gas-liquid separation tank 11. It is separated into gas and liquid (for reference, a cross section of the gas-liquid separation tank 11 is shown in FIG. 2).

That is, the slurry jet in the gas-liquid separation tank 11 rotates regularly in a fixed direction in a spiral shape, and as a result, the air flow is stably separated and the gas-liquid fraction l! It is discharged from an exhaust port 1 lb provided at the upper part of the II tank 11. Therefore, the airflow turbulence caused by the slurry shaking, which was observed in the conventional apparatus, was completely eliminated by installing the gas-liquid component 11.

Incidentally, even if the cylindrical part 10 is made of only the straight pipe part 10a and connected to the upper part of the gas-liquid part 11 and the deflection plate 13 is provided in the separation tank 11 as shown in FIG. 3, for example, as shown in FIG. The slurry jet can be rotated in a spiral as in the case of using the curved pipe portion 10b, and this case is advantageous in terms of layout.

Conventionally, the entire inside of the spray tank was replaced with an inert gas to prevent oxidation of the metal powder, but in the device of the present invention, for example, the lower part of the spray nozzle 2 is sealed to be isolated from the outside air, By supplying the active gas from the top of the spray nozzle, it is possible to easily replace the atmosphere in the cylindrical portion 10 where the spraying is performed with an inert gas.

In addition, by adjusting the supply amount of this inert gas, it is possible to adjust the pressure at the top of the spray medium jet, and by changing the diameter length of the cylindrical part, the pressure at the bottom of the spray medium jet can also be adjusted. It can be adjusted in the range from vapor pressure to atmospheric pressure.

In addition, the problem of adhesion and accumulation of metal powder on the inner wall surface, bottom surface, etc. of the spray tank, which was observed in conventional devices, can be solved because the cylindrical portion 10 is constantly cleaned by the passage of a high-speed spray medium jet. Resolved.

Moreover, since the slurry was constantly rotating in the gas-liquid separation tank 11, there was no powder adhering to the wall surface of the separation tank 11.

Furthermore, since the device of the present invention can stably discharge slurry from the discharge slurry port 11a, the slurry can be directly discharged from the dehydrator 12, such as a centrifugal sedimentation type or a filtration type, without storing it in a tank or the like.
In addition, it is possible to supply slurry as it is sprayed, which avoids problems such as metal powder adhesion to storage tanks and oxidation of metal powder, which were previously observed, and also eliminates overloads and powder clogging that were observed in slurry bombs, dehydrators, etc. There were no more problems.

As a result of producing metal powder using the apparatus of the present invention, stable spraying, which had not been seen before, was achieved, and the particle size distribution of the obtained metal powder was narrow, and the particle size was stable both within and between lofts. In addition, the device of the present invention does not require the huge jets and holes found in conventional metal powder manufacturing devices, reducing the construction cost of the manufacturing device. Note that the length of the tray-shaped part 10 of the present invention varies because the length required for solidifying the molten metal differs depending on the particle size of the target metal powder, and when the particle size is about 50 μm, it is necessary to be 1.5 m or more. However, if the thickness is about 10 μm, it may be about 0.5 m.

However, the effect of the present invention can be obtained even if the length is longer than this. Examples> The present invention will be specifically described below based on Examples.

(Example 1) SUS3 1 6L composition stainless steel with a capacity of 200 kg
The metal powder is melted using a high-frequency melting furnace, heated to a temperature between 1,600 and 1,750°C, and poured into a preheated tundish in the metal powder manufacturing apparatus of the present invention shown in FIG. A molten metal stream was flowed down from a tundish nozzle with a diameter of 1 to 8 mm. Water pressure of 150 to 1000 kg 7 cm2 is applied to this molten metal flow,
Water amount 0. 1 ~ 0. Atomization was performed by jetting and colliding water at a rate of 23 m'/min.

The diameter of the vibrator in the cylindrical part needs to be changed if the particle size of the powder produced differs depending on the spray conditions such as water pressure, but if the water pressure is 5.
00 to 1000 kg/cII+2, when the tundish nozzle diameter is 1 to 5 mm, the inner diameter is 40 to 60 mm.
, a length of 1 to 2 m was used.

The shape of the gas-liquid separation tank shown in Figures 2 and 3 was used. In any case, stable spraying of the spray medium is obtained, and the obtained metal powder does not adhere to or accumulate on the walls, bottom, etc. of the apparatus, and the yield is lower than that of Example 1 of the present invention. 3). The results are shown in Table 1. In addition, when the slurry continuously discharged from the gas-liquid fraction III 4I was continuously dehydrated using a centrifugal sedimentation type and a filtration type dehydrator, the problems caused by sedimentation of metal powder that were observed with conventional equipment were completely eliminated. I was able to dehydrate quickly without any problems.

Table 1 Effects of the Invention Since the present invention is configured as explained above, by using the apparatus of the present invention, it is possible to stabilize the airflow in the spray area and produce metal powder with less generation of coarse particles. At the same time, there is no adhesion of powder to various parts within the apparatus, and metal powder can be recovered with a high yield due to a stable jet of spraying medium and without contamination with different brands.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of the metal powder manufacturing apparatus of the present invention. FIG. 2 is a cross-sectional explanatory diagram of the gas-liquid portion 11 in FIG. 1. FIG. 3 is a schematic diagram showing another example of the gas-liquid tank Ill1 according to the present invention. FIG. 4 is an explanatory diagram of a conventional general metal powder manufacturing apparatus. FIG. 5 is an explanatory diagram of an apparatus in which a structure is provided inside ojIn4if. FIG. 6 is an explanatory diagram of a conventional device having a cylindrical portion. FIG. 7 is an explanatory diagram of a conventional device for stirring the inside of a spray tank. Description of symbols 1... Tundish, 2... Spray nozzle, 3... Spray oak, 4... Melting furnace, 5... Spray medium jet, 6... Molten metal, 7...・Spray part, 8... Wave-dissipating structure, 9... Simple guide, 10... Interrogation part, 10a... Straight pipe part, 10b... Bent pipe part, 11... Gas-liquid separation tank, 1a... Exhaust slurry, 1b... Exhaust port, 2... Dehydrator, 3... Deflection plate FIG. 1 10b FIG. 4 FIG. 7

Claims (3)

[Claims] (1) In an apparatus for producing metal powder by injecting a liquid atomizing medium into a molten metal flow, a length that allows solidification of metal fine particles generated by the atomizing medium injection is provided at the bottom of a nozzle that injects the liquid atomizing medium. 1. An apparatus for producing metal powder, comprising a gas-liquid separation tank having a cylindrical part, through which slurry flowing down is rotated and charged in a spiral manner. (2) The apparatus for producing metal powder according to claim 1, wherein the cylindrical part comprises a straight pipe part and a curved pipe part for rotating the flowing slurry in a spiral shape and charging it into the gas-liquid separation tank. (3) The metal powder manufacturing apparatus according to claim 1, wherein the gas-liquid separation tank has a deflection plate for rotating the slurry in a spiral shape.