JPS5832567A - Manufacture of metallic shot - Google Patents

Abstract

PURPOSE:To obtain metallic shot of desired uniform grain sizes by placing the tip of a nozzle on or blow the water surface and dropping molten metal through the nozzle thereby solidifying the same. CONSTITUTION:Metal of 300-600 deg.C m.p., for example, Zn, Cu, Ag, Sn, Pb, Al or their allot is melted by using a nozzle receiver 1 made of refractories. The molten metal is dropped through a nozzle 4 of which the tip is placed on or below the water surface 8 of the water 10 stored in a water tank 7 into the water 10. The temp. of the water 10 is kept at 60-70 deg.C by replenishing cold water therein. The molten metal cools and solidifies to form shot 12. The formed shot 12 is captured with a removing cage 9 in the bottom part of the tank 7. The yield is 93-98%.

Description

[Detailed description of the invention] The present invention relates to a novel method for manufacturing metal shot.

When dissolving a metal as an ion source in electroplating, for example, a metal with a relatively low melting point such as zinc or a zinc-based alloy such as a zinc-iron alloy, a metal with a constant particle size and, for example, a particle size of 2 to 3 A detailed shot of the same level as the φ is desired.

A conventional method for manufacturing metal shot, for example, as disclosed in JP-A-55-158875, involves pouring molten metal from a molten metal reservoir with a dripping nozzle at the bottom end, and placing the end of the dripping nozzle at an appropriate point above the water surface. The basic method is to hold it at a height (2) and cool it under water (2).

However, with the conventional method, it is difficult to obtain spherical shots with a constant particle size, and there is a problem in that many shots with coarse diameters, elongated grains, and flat grains are produced.

The present invention obviates the above-mentioned disadvantages of the conventional method, and the inventor's object is to provide a fine shot having a constant particle size as described above. That is, the present inventor has proposed a method for manufacturing a metal shot lump by passing a molten metal through a nozzle and solidifying it underwater (three ways), by setting the tip of the nozzle at or below the water surface and letting the molten metal fall into the water and solidify. Achieve the above objectives.

The present invention will be described in detail below with reference to Examples.

In the metal shot of the present invention, molten metal heated to a predetermined temperature is poured into a molten metal reservoir with a dripping nozzle of a predetermined diameter at the lower end at two heights to generate an appropriate pressure, and the molten metal is maintained at an appropriate temperature. It is obtained by immersing a nozzle in the liquid level of the cooled water, letting it drop into the water, and cooling it with water.

Metals particularly suitable for the present invention are zinc or zinc-based alloys such as zinc-based iron alloys, and the present invention may also be applied to copper, silver, tin, lead, aluminum, or alloys thereof. Generally, metals having a melting point of about 300 to 600'C can be made into shots by the method of the present invention.

The heating temperature of the molten metal is selected appropriately according to each metal, and the nozzle diameter is determined mainly according to the target uniform particle size range, and other factors such as the temperature of the cooling water, the depth of immersion of the nozzle below the water surface, and the nozzle material are determined. By setting the factor,
Metal shot with the desired uniform particle size is obtained.

A more detailed explanation will be given below based on the case of manufacturing zinc shot.

As described at the beginning, zinc shot having a uniform particle size of about 2 to 3 grains is desired, and an example of its production is as follows.

The nozzle has a diameter of 0.5 to 2.5N, preferably 1.5N.
It is preferable to use a material with a low thermal conductivity of 0 to 2.0111, such as a ceramic nozzle, in order to prevent nozzle clogging. As the ceramic nozzle is immersed in water, a heat-resistant ceramic material having thermal shock resistance is preferably used, such as heat-resistant crystallized glass having a crystallization temperature of 700°C or higher, alumina material (preferably high alumina material), etc. ) Ceramic materials, zircon materials, aluminum titanate materials, etc. can be used.

Examples of crystallized glass include so-called machinable glass ceramics, which have synthetic mica microcrystals as a crystal phase and are preferably machinable, and others have cordierite as a crystal phase. Generally, it is advantageous to use a ceramic nozzle material with a thermal conductivity of 0.01c, 14/at·see'C or less in order to prevent the molten metal from clogging in the nozzle hole.

The immersion depth of the nozzle under the water surface requires at least a state of contact with the liquid surface, and is determined by the shape of the nozzle and the device, etc., and is generally about 0 to 50,111 degrees, preferably about 2 to 20 degrees, although it is not an essential limitation. .

However, it is not necessary to immerse the molten metal too deeply, and it is sufficient to avoid unnecessary cooling of the molten metal reservoir and nozzle.

The water temperature needs to be maintained at a specified temperature in order to obtain shots with a spherical shape and uniform particle size, and is generally determined depending on the temperature of the molten metal, the type of metal, etc. In the case of zinc, the temperature is approximately 50 to 80°C, preferably 60 to 70°C, but the optimum water temperature varies to some extent depending on the nozzle diameter.

Note that here (: Zinc refers to zinc ingot with a purity higher than that of distilled zinc ingot. Regarding this water temperature, for example, zinc-based iron alloy (Fe < 2.5%, the balance has a purity higher than that of distilled zinc ingot). In the case of (zinc metal), the optimum cooling water temperature decreases depending on the iron content, and is 15 to 60 °C for 1% Fe and 10 to 40 °C for 2.5% Fe.The nozzle diameter is determined depending on the desired particle size. Although the particle diameter varies, it needs to be within a certain range in order to obtain spherical shot with a uniform particle size.In the case of zinc, it is approximately 1.0 to
2.5M, preferably 1.0-2. It is about OW. In addition, in the case of a zinc-based iron alloy, the nozzle diameter may be the same as that of the beam.

Next, the temperature of the molten metal is basically determined depending on each metal, but for zinc it is approximately 475-550℃, preferably 485-53℃.
0°C, and for zinc-based iron alloys (composition listed above), the melting point plus about 10°C or more, the melting point plus about 130°C or less, and about 70°C.
The temperature is preferably 0°C or lower.

Under the above conditions (when carried out twice), according to the present invention, for example, zinc shot with a particle size of +2H to -41'l is
A uniformity of 0 to 90 degrees or more, 93 degrees or more under suitable conditions, and 98% or more under optimal conditions can be obtained, and the allowable molten metal temperature range is wide from 475 to 550 degrees Celsius, and the allowable water temperature range is also wide, making operation extremely easy. Therefore, no nozzle clogging occurs.

Even if one zinc-based iron alloy (mentioned above) is used, particles with a uniform particle size similar to ZO can be obtained.

A metal such as zinc is preliminarily melted, and the molten metal has a nozzle 4 (diameter d) at the bottom C2 as illustrated in FIG. A predetermined temperature (-) is maintained in the reservoir (nozzle receiver) 1.

Usually, the nozzle receiver 1 is held above the water surface so that only the tip of the nozzle 4 is submerged a predetermined height h) below the water surface, and the temperature is maintained by known heating means as necessary.

The water tank 7 illustrated in FIG. 1 has a water temperature adjustment mechanism (not shown).
and a stirring device (not shown) and shot extraction means (basket 9, etc.) as necessary. The water depth is adjusted to a depth suitable for uniformly cooling the shot (usually O14
~2m).

Examples will be described below (% indicates weight %).

Example 1 Pure zinc ingot (Zn 99.99%, Pb O,00
12%.

CdO, 0007%, FeO, 0007~0.0
01%), pour the molten zinc into the spout 2 using the refractory nozzle receiver 1 shown in FIG. Temperature (inside nozzle receiver 1) at each temperature of 475 to 550℃ (:
Maintains constant temperature and uses machinable glass-ceramic nozzle material (thermal conductivity 0.004 cal/see -ax)
-'Cat25℃2 Weight composition 5i0246 L AJ
20.16%.

MfO17chi, K, 010chi, F4 sword, B2037chi), and the nozzle diameter is 1 to 2. Off, the immersion depth between the nozzle tip and the cooling water surface is maintained at h = 51EI, the temperature of the cooling water is changed from 50 to 80°C in steps of 10°C, and the molten metal 5 is poured into the nozzle on the bottom of the hot water storage section 11. 4 into the cooling water 10 (for 5 to 20 minutes).

As illustrated in FIG. 1, the cooling water tank 7 has a depth of 1 m and has a shot extraction basket 9 at the bottom, and the water temperature is controlled by replenishing cold water.
A predetermined temperature was maintained in each case by a heating device (not shown).

Nozzle diameter d=1. In off, the molten metal temperature is 500-55
0℃, water temperature 60~70℃, shot diameter +2~-4n, product yield 80~90 inches, -4ff is 10
It was 0chi.

When the nozzle diameter d=1.51111, the results shown in Table 1 were obtained, and the particle size yield was 93 to 98 inches.

When the nozzle diameter d=2.0111, the conditions were set strictly (as shown in Table 2, the yield was changed from 84 to 93 inches).

Note that all shots are spherical and have a spherical shape. Ta.

Example 2 The same experiment as in Example 1 was repeated with the tip of the nozzle brought into contact with the water surface (two times), and similar results were obtained.

Example 3 Using the same purest zinc metal (as used in Example 1), Fe
A zinc-based iron alloy containing O, 88-1.07% was obtained. The molten metal was dropped into water at a temperature of 50 to 70°C at a temperature of 460 to 480°C with a nozzle diameter d=1.0IIN.

Other conditions are the same as in Example 1. As a result, uniform spherical shots 12 with a yield of 85 to 95 inches were obtained.

Comparative Example Using the same zinc metal as in Example 1, the nozzle was installed above the water surface according to the conventional method. As a result of dropping the shot into water under the same conditions as in Example 1, the resulting shot did not have a spherical shape, but contained flat, elongated, and coarse particles with tails. The product yield is 50
It was ~70%.

In addition, as a condition specially set by the present inventor, when the distance between the nozzle end and the water surface is 8WM, the nozzle diameter is 1.0~
1.5mm+, water temperature 70-80℃, molten metal temperature 450-5
At 50 DEG C., the yield of the product was changed to 77 to 87 inches, but the -4 mm yield remained at 80 to 94 inches, and coarse grains and fine grains were produced.

Below, remaining white

[Brief explanation of the drawing]

FIG. 1 shows a schematic view of an apparatus for carrying out the method of the present invention, and FIG. 2 shows a cross-sectional view of a nozzle receiver. 1... Nozzle receiver 2... Pouring spout 3...
Dross removal plate 4... Nozzle 5... Molten metal
7...Aquarium 8...Water surface
10...Wed 12...Schott patent applicant Asamichi Kato, representative patent attorney for Nippon Mining Co., Ltd. 1st cause

Claims (1)

[Claims] 1) A method for producing metal shot by dropping and solidifying molten metal into water through a nozzle, characterized in that the tip of the nozzle is located at the water surface or one inch below the water surface.