WO1986003700A1

WO1986003700A1 - Method of manufacturing spheroidal metal granules

Info

Publication number: WO1986003700A1
Application number: PCT/JP1984/000613
Authority: WO
Inventors: Ritsue Yabuki; Junya Ohe
Original assignee: Mitsubishi Kinzoku Kabushiki Kaisha
Priority date: 1983-11-25
Filing date: 1984-12-24
Publication date: 1986-07-03

Abstract

Spheroidal metal granule manufacturing method in which a molten metal or alloy in a container of a refractory is arranged to drop in the form of a small droplet from a small-diameter nozzle provided in the bottom of the container and is solidified in a cooling medium to thereby obtain a metal granule, the method comprising the steps of: employing the small-diameter nozzle having one or more vertical bores with an inside diameter of 0.3 to 3.0 mmo/; making the molten metal drop from the nozzle into a cooling liquid constituted by two layers, that is, an upper layer of an oil having a viscosity of ISOVG 10 to 680 (International Standards of Viscosity Grade) and a lower layer of water; and passing the molten metal through the liquid such that the molten metal is solidified and cooled, whereby it is possible to manufacture spheroidal metal granules having a uniform shape at high yield and efficiency.

Description

Specification

[Title of Invention]

Method for producing spherical metal particles

〔 Technical field 〕

The present invention relates to a method for producing spherical metal particles (including alloys) having regular dimensions.

[Background technology]

In recent years, for the purpose of improving sharpness and prolonging the life of cutting blades such as saw blades for sawing, for example, a cemented carbide tip (made of WC-Co sintered alloy) is brazed or a Co-based surface hardening alloy [eg Statorite ¾ 1 (Co-30 wt ¾ Cr-1 12 wt ^ W-2.5 wt C!)] Etc. are hand-welded with oxygen-acetylene gas (hereinafter referred to as "gas-welded JT welding"), It has generally been the case that it is hard-cured.

On the other hand, the exhaust pallets and intake pulp shaft ends of gasoline engines and diesel engines require particularly wear resistance because they are struck by the mouth force arm each time the pal: / is opened or closed. Usually, the above-mentioned stellite 1 is hard-welded by overlay welding, but in recent years, it has been possible to reduce the amount of welding even to the difficult axis of welding such as the thin and gas-like welding like pulp for small engines. It has become necessary to supply a fixed amount of surface-hardened alloys in order to carry out hard metal hardening work.

On the other hand, in the continuous ironmaking of copper alloys, the raw material mother alloy is used to add the active metal, but in the case of continuous casting, the molten metal is retained in the furnace for a long time, so its surface Part of the active metal acid It is said that the change occurs and component fluctuation occurs. Therefore, in order to compensate for the oxidative loss of the active metal, it is necessary to continuously add the active metal to the molten metal in small amounts at a constant rate and continuously. At present, the supplementary addition of such an inactive metal component is carried out by weighing a plate material, a lump material, or a chip-shaped material and intermittently introducing it by hand.

By the way, recently, an automatic welding device has been developed that automatically builds up a surface hardening alloy on the cutting edge of a band saw for sawing, which has made it possible to automate the build-up / grinding work and save labor. Came.

In addition, automatic welding equipment is being developed for overlay welding of shaft ends of engine pulp. In addition, automation studies are being added to the work of adding the active metal master alloy in the continuous production of copper alloys.

Then, in automating each of these operations, it is most preferable that the build-up alloy and the supply mother alloy have a shape in which granular or spherical rollers are easily formed, and that continuous quantitative addition is carried out while this is done. It is being adopted as a thing.

Therefore, the shape of the supply metal alloy in the automatic metallurgical device for surface hardening metal alloy should be changed from rod to grain! ), And the demand for active metal master alloys added to copper alloys has changed to spherical ones and having a certain weight.

From the above, it is essential to manufacture spherical metal particles having desired dimensions and no fluctuations in order to promote the automation of supply of hot-melt alloys and mother alloys. Conventionally, various means for directly producing metal particles from a molten metal have been proposed and actually used. However, spherical metal particles (below It is extremely difficult to manufacture (including alloy particles below) ??, but we have not yet been able to solve various problems such as the following.

That is, the means for directly producing metal particles from a molten metal was mainly used for low melting point metals such as tin, pig iron and zinc, but as a typical example thereof, a saucer (tundish with many small holes is used. It is possible to pour the molten metal into), drop the molten metal into the small holes and drop it into water or low-viscosity oil, and allow it to solidify.

However, in the case of producing metal particles by this method, the size of the liquid droplets became teardrop-shaped and the sizes were not uniform]), and when the liquid droplets dropped into water or oil, the shape collapsed. B) Because of the fine dispersion, the rate of spherical metal particles of a given size was not good).

Further, when such a method is applied to a metal having a high melting point and a very low ductility, such as a surface hardening alloy such as stellite, there is a problem that cracking occurs due to thermal strain due to quenching.

[Summary of Invention]

From the above viewpoints, the inventors of the present invention particularly find a method of producing a spherical metal particle having a desired size and a high yield, which can be applied to a metal having a high melting point and poor workability. Focusing on the high efficiency of the method of directly obtaining metal particles from the molten metal, various studies were conducted on the structure of the refractory container and nozzle used for it, the heating melting and dropping means, and the solidification-cooling means. As a result, the following findings (a) to () have been obtained.

(a) At the bottom of a refractory container containing molten metal, A tubular small-hole nozzle having one or two or more vertical holes was attached, and when the molten metal was dropped through this nozzle, the molten metal droplet became a nearly spherical shape without forming a teardrop shape. And then fall,

(b) Even if the nozzle is brought close to the coolant, it is unavoidable that the liquid droplets of the molten metal that fall into contact with the coolant will deform to some extent. When the droplet is dropped directly into it, it rapidly cools and solidifies in a collapsed form, whereas the molten metal droplet drops into oil of a specific viscosity. When cooled in oil, the cooling speed of the droplets is slow in oil, so some deformation due to the rounding force of the droplets (surface tension) is corrected and the droplets solidify into the desired spherical shape. thing,

(c) Furthermore, when not only an oil of a specific viscosity is used as a coolant but also a two-layer type cooling liquid having a water layer below the oil is used as a coolant, the molten metal falling into this The droplets first form a spherical solidifying shell in the oil layer, then reach the water layer and are completely solidified, so that the cooling tank can be made shallower and shrinkage cavities are reduced. Intrusion of water or oil into the metal particles can be suppressed as much as possible.Furthermore, the metal particles that have fallen into the oil and started to solidify are attached to the metal particles by being circulated through the water layer. The amount of oil taken out of the cooling tank is small] 9, and the cleaning process is easy.

This invention was made based on the above findings i),

The metal in the refractory container or the molten alloy prepared to the specified composition is dripped into a small liquid droplet from the small hole nozzle provided at the bottom of the refractory container and solidified in the coolant. In the method for producing metal particles, the small hole nozzle has an inner diameter of 0.3 to 3.0 Use one that has one or two or more straight holes, and the molten metal droplets from this small hole diameter nozzle have an upper layer viscosity: ISO (International Viscosity Standard) VG

By dropping it into a two-layer cooling liquid with 10 to 680 oil as the lower layer of water and allowing it to pass through the liquid to solidify and cool the liquid, a spherical metal particle with an organized shape is formed. It has a high yield and can be manufactured with high efficiency.

It has something special about it.

[Best Mode for Carrying Out the Invention]

The refractory container used in the method of the present invention is a tundish type container that simply holds molten metal and keeps it warm, or has a carbon heating element for keeping warm outside, and stores it by high-frequency induction heating. In other words, it means anything that can hold molten metal and supply it to the outside of the container through a nozzle at the bottom, such as a crucible furnace type.

Also, the inner diameter of the vertical hole of the small hole diameter nozzle provided at the bottom of the refractory container is limited to 0.3 to 3.0 hulls because the surface of the molten metal is limited if the inner diameter of the vertical hole is less than 0.3 »0. Even if the molten metal is added due to the tension, it does not flow down from the nozzle to the extent that it can be used practically. The reason is that even if it falls into the oil layer, it will not form a metal particle of a fixed shape in the shape of a pearl or a teardrop. And, in order to stably obtain the desired spherical metal particles, it is preferable to adjust the inner diameter of the vertical hole of the nozzle to about 0.5 to 2.0, and to improve workability and maintenance. From a theoretical point of view, it is recommended to replace the nozzle with a firing nozzle that can be freely replaced. If the nozzle hole is provided vertically, It becomes difficult to obtain granular droplets.

Furthermore, the viscosity of the oil used as a coolant is limited to ISO VG "10 to 680. When the viscosity of the oil is less than IS0V & 10, the speed of the molten metal droplet passing through the oil layer is high due to insufficient viscosity, Shaped droplets are shaped into spheres and the thickness of the oil layer required to form a solidified shell increases!), And it becomes necessary to deepen the cooling tank.

If the viscosity exceeds IS OVG 680, this time, it may be feasible that the droplets cannot be shaped into a spherical shape due to excessive viscosity this time, or the amount of oil carried into the water layer by metal particles increases. Because of the reason. Of course, oil that does not have fluidity such that metal particles stay in the oil layer can be used.

If possible, the cooling oil should have a viscosity of IS 〇VG "10 to 680, and it should have a viscosity of S OV & 3 2 to 460 (equivalent to SAE l 0W to SAE 10). Those with are recommended.

If the viscosity of the oil used as the coolant is within the above range, the molten metal droplets can be solidified into the desired spherical shape, but if workability is taken into consideration, the flash point .: 150 ° It is preferable to use a lubricating oil of C or higher (preferably -200 ° C or higher) (whether for automobiles, ships, industrial use, or general use). This is because the refractory container that holds the molten metal is close to the surface of the oil, which is the cooling liquid, so that there is no risk of oil ignition.

However, in the case of oils with a low flash point] (for safety, it is also possible to use oils with a flash point of 150 ° C or higher), the surface of the oil layer should be inert gas or carbon dioxide. It is possible to prevent the oil from catching fire by covering it in a gas atmosphere and performing the work. The thickness of the oil layer may be such that the molten metal droplets can form a spherical shell on the surface while passing through the layer, and, of course, the droplets are completely solidified in the oil layer. It doesn't matter.

By the way, the value of the inner diameter of the nozzle vertical hole, the viscosity range of the cooling oil, etc. as described above may not be applicable only to the production of spherical particles such as surface hardening hardfacing alloy and copper master alloy like Stellite. Needless to say, it is also a condition for surely forming spherical particles of various other metals or alloys.

As the material for the refractory container and the nozzle, any material generally known as a material for handling molten metal such as aluminum, magnesia, and zirconia can be used] 9, The particle size can also be appropriately selected depending on the type of metal, the size of spherical metal particles to be produced, and the like.

[Brief description of drawings]

FIG. 1 is a schematic vertical cross-sectional schematic view of one example of a molten metal dropping device (refractory container) used in the present invention, and FIG. 2 is a vertical section showing another example of the molten metal dropping device used in the present invention. FIG. 3 is a schematic diagram of a plane, and FIG. 3 is a schematic diagram of a vertical cross section of the spherical metal particle manufacturing apparatus used in the examples of the present invention.

The refractory container shown in Fig. 1 consists of an aluminum crucible 3 with a small hole nozzle 2 made of aluminum and having a plurality of vertical holes 1 at the bottom J? The outside of 3 is surrounded by a heating element 4 made of carbon, and it is located inside a high frequency induction heating coil 5. The reference numeral 6 indicates that the heating element 4 made of carbon dioxide and the high-frequency induction heating coil 5 are held and the radiant heat is applied. Alumina refractory for heat insulation.

When manufacturing metal particles, the raw material alloy 7 previously melted to the desired composition is charged into the crucible 3, heated and melted by the high-frequency induction coil 5, and the liquid from the lower end of the small hole nozzle 2 is melted. Drop 8 into the cooling liquid.

Also, in Fig. 2, it is applied when the diameter of the vertical hole of the nozzle is extremely small. The main part has the same structure as that shown in Fig. 1 (in Fig. 2, those having the same function as in Fig. 1 are denoted by the same reference numerals), but in this example, the crucible 3 The opening of the is covered with a refractory wool 9 for preventing leakage of inert gas (including reducing gas), and a lid 11 having an inlet 10 for inert gas (including reducing gas) is used. Therefore, it is possible to pressurize the melted raw material alloy 7 with an inert gas, so that even if the diameter of the vertical hole 1 of the small-diameter nozzle 2 is small, the droplet will be smoothed. It is possible to drop it.

〔 Example 〕

Next, the present invention will be described by comparing Examples with Comparative Examples.

First, commercially available surface-hardening alloys A and B having the composition shown in Table 1 and mother alloy C for adjusting the composition of a round bar with a diameter of 4.8 difficult and a square bar of 15 rai X 10 rai And prepared.

Then, each one of these raw materials was melted using an apparatus as shown in FIG. 3, and dropped into a cooling liquid to produce each spherical alloy grain.

Of the equipment shown in Fig. 3, the refractory container is Similar to the one shown in Fig. 1 except that there is one vertical hole in the crane.

D (symbols of each part are the same as in Fig. 1), Drop of liquid droplet'Coagulation part is as follows. That is, below the alumina refractory material 6, there is provided a heat insulating water cooling board 13 for preventing the temperature of the cooling oil 12 from rising due to the radiant heat of the heating element. It is equipped with an inert gas inlet 14 for introducing an inert gas to prevent this.

A cooling cylinder 15 and a spherical metal particle receptor 16 are arranged next to the water cooling board 13 for heat insulation.] Inside the cooling cylinder 15, cooling oil 12 and cooling water 17 are contained in a two-layer state. There is. The reference numeral 18 indicates a water-cooled corrugated pipe for suppressing the temperature rise of the cooling oil 12, and the reference numeral 19 indicates spherical metal particles.

Further, in this embodiment, the vertical hole diameters are different for each alloy shown in Table 1 above.

Alloy A ··· () .6 Recommendation 0,

Alloy Β ··· 0.7 ηπ Φ,

Alloy 0 ··· 1.5 ηπ,

Applying a small hole diameter nozzle, the viscosity of the cooling oil is

Alloy… I S O V G 3 2,

Alloy B ~ I S O V G 220 0,

Alloy C! … I S 0 V G 460,

The lubricating oil of was used.

The average weight and weight distribution of 100 alloy particles randomly sampled from each spherical alloy particle, which was dropped from a small-diameter nozzle and passed through two layers of lubricating oil and water and solidified and cooled, were investigated. Shown in Table 2 did.

From the results shown in Table 2, it is clear that according to the method of the present invention, the weight distribution is very good, and almost spherical alloy particles can be obtained. The relationship of distribution is clear.

Then, for alloy A, the vertical diameter of the nozzle was set to 0.1 rai? ⁵ , 0.3 wisteria 0, 0.5 dragon 0, 0.6 mm Φ, 0.7 τιιπ, 0.8 basket 0, 1 0.0 mm, 1.5 ΜΜ, 2.0 ■ Φ, 3.0 j »0 and 4.0 were changed to produce the alloy grains, and the results shown in Table 3 were obtained.

The results shown in Table 3 indicate that the molten metal did not flow out when the vertical hole diameter of the nozzle was 0. 1 sq. 0 (it did not flow out even when pressurized with Ar gas), while the molten metal was continuous at 4.0 Peng. It has been found that it is not practical because the product grain shape becomes a continuous beads or a teardrop shape, and in addition, there is a risk of ignition and a decrease in viscosity due to a rise in the temperature of the lubricating oil. .

From this, it was confirmed that it is necessary to set the inner diameter of the vertical hole of the small hole nozzle to 0.3 to 3.0.

Alloying composition (weight)

Remarks

Type C Γ Fe W Si B Go + Impurity Ni + Impurity Cu + Impurity

; A 2.51 30.04 12.01 1.02 Co—W alloy

B 0.76 15.02 4.15 4.05 3.48 Ni—B alloy

C 1.76 Cu—B alloy

2 Alloy average weight Straight cloth (pieces)

Type 154 ~: 182 183 ~ 242 243 ~ 285 286 ~ 32 360 ~ 50 Lord 505 ~ 540 541 ~ 567

A 212.4 2 92 6 0

B 251.6 1 22 70 7

C 501.7 1 3 73 14

3

[Industrial availability]

As described above, according to the present invention, spherical metal particles of a desired size can be mass-produced relatively easily in a single cylinder and at a high rate of mass production. , A shot for automatic build-up on the shaft end of engine pulp, or a shot for automatic addition of activated metal mother alloy during copper alloy continuous mirroring, enabling high-efficiency production of general-purpose spherical metal particles. This is because it brings about an industrially useful effect.

Claims

The scope of the claims

1. Molten metal (including alloys) in a refractory container is dripped into small droplets from a small hole nozzle provided at the bottom of the refractory container and solidified in a coolant to produce metal particles. In this method, as the small-diameter nozzle, one having 1 or 2 or more vertical holes with an inner diameter of 0.3 to 3.0 m 0 is used. : IS 0 VG (International viscosity standard) 10 ~

A method for producing spherical metal particles, which comprises dropping 680 oil into a two-layer cooling liquid having a lower layer of water, passing through the liquid to solidify and cool.

2. The method for producing spherical metal particles according to claim 1, wherein the inner diameter of the vertical hole is 0.5 to 2.0.

3. The method for producing spherical metal particles according to claim 1, wherein the viscosity of the upper layer cooling liquid is I S O -VG 3 2 to 460.