JPS6233300B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a blast shot and a method for manufacturing the same. In particular, the present invention relates to a zinc alloy shot having hardness and other properties suitable for blasting die-cast products, and a method for manufacturing the same.

Blasting is a well-known method for cleaning metal surfaces. The blasting method is a method of removing scale and the like adhering to the surface of the object by projecting particles onto the surface of the object.

Generally, when shot blasting a die-cast product, it is desirable to change the blasting shot material depending on the material to be blasted, and usually the same type of metal shot as the material to be blasted is used.

However, when blasting aluminum die castings or small die castings, aluminum cut wire has a high risk of explosion of powdered aluminum, so steel shot or stainless steel cut wire is used.

However, when a steel shot is used, rust occurs due to adhesion of powdered iron powder.
Furthermore, when stainless steel cut wire was used, there were problems such as deep cutting at the edges and scratches on soft aluminum die-casting and the like.

Therefore, as an alternative to this, zinc shot has recently become important, and due to its moderate softness and other physical properties, zinc shot has a good blasting effect without damaging the material, and does not damage the aesthetic appearance or corrosion resistance of the product. do not have.

In general, zinc shots for blasting are manufactured by shooting high-purity zinc, which is called the purest zinc.

It has been found that when such zinc shots are used to blast aluminum die-cast products in particular, blackening of the die-cast surface can occur.

Various factors can be considered for this blackening, but it has been found that one of the factors is to increase the hardness of the zinc shot a little more than before.

Therefore, the present inventor has already disclosed an invention in which a small amount of iron is added, and was able to obtain a shot with higher hardness and less brittleness.

That is, in the present invention, Pb0.03~15%, Fe0.04~2.0
This invention relates to a zinc alloy containing % residual zinc and impurities, which is used as a blasting shot. Furthermore, the present invention relates to a method for producing a blast shot, in which a molten zinc alloy consisting of 0.03 to 15% Pb, 0.04 to 2.0% Fe, remaining zinc, and impurities is dropped into water at a temperature of 20° C. or less to form a shot.

The present invention will be explained in detail below.

The composition of the target alloy in the present invention is lead 0.03 to 15
%, and is a zinc alloy with 0.04% to 2.0% iron.

The lower limit of lead was set at 0.03% because below this the hardness would not exceed the target Hv = 40, and the upper limit was set at 15% because it was the upper limit at which lead could be mixed in a supersaturated state with respect to zinc. It is.

In addition, the lower limit of iron was set at 0.04% because below this, the hardness would not exceed the target Hv = 40.
The upper limit was set at 2.0% because if the content exceeds 2.0%, the brittleness will increase and the life of the blast shot will be shortened.

There are various methods of shotting, such as a spray method and a collision method in which the molten metal is poured down onto a disk to disperse it, but among these methods, a method in which the molten metal is allowed to fall naturally into water is preferred.

In this case, it is desirable to drop it into water whose temperature is below 20°C. This is because a hardness of Hv=40 or higher can be easily obtained.

Also, to easily obtain hardness, add 0.3% lead.
As mentioned above, by setting the iron content to 0.08% or more, the water temperature can be reduced.
It was found that high hardness (Hv=40 or higher) can be obtained even at around 40°C.

In this case, by using iron dross generated during zinc smelting as the additive material, the alloy has good solubility and the above-mentioned objective alloy can be easily produced.

For example, iron dross has the following components.
That is, it consists of 5-15% lead, 1.0-3.0% iron, 0.1-0.2% other impurities, and the remainder zinc.

The zinc shot for blast shot of the present invention is
It is suitably produced by the following method.

Zinc molten metal temperature: 530-670℃ Nozzle hole diameter: 0.5-0.8mm Distance from the bottom of the nozzle to the water surface: 10mm or less Water temperature: 50℃ or less, preferably 20℃ or less Nozzle: Ceramic The zinc alloy shots produced in this way are
They are mainly spherical shots with a particle size of ~2000μ, especially 1000-1400μ. Bitskers hardness is 40
~60, and is suitable for blasting various die-cast products, especially aluminum die-cast products.

As described above, the following effects were obtained by the alloy and manufacturing method of the present invention.

(1) Since it contains not only iron but also lead to increase its hardness, it is less brittle and has a longer lifespan as a zinc shot for blasting than those containing only iron.

(2) A certain degree of hardness can be obtained without lowering the water temperature.

(3) By using iron dross generated during zinc smelting, it has become possible to easily produce zinc alloy shot containing iron and lead.

(4) Unlike aluminum, there is no risk of dust explosion, and compared to shots made only of zinc, the product does not turn black.

Example Iron dross generated in zinc smelting (component: lead 7.8
%, iron 1.64%, and other impurities (residual zinc 0.16%) to obtain a zinc shot blast shot with 0.35% lead and 0.10% iron.

In this case, the treatment was carried out at a hot water temperature of 550°C and a water temperature of 15°C, and the obtained hardness was Hv = 51 to 63.6.

When treated at a water temperature of 40°C, Hv=46-59 was obtained.

Therefore, even if the water temperature rose due to the molten metal, it was easy to obtain a certain level of hardness.

Comparative Example When Pb was added dropwise to a sample containing only 0.5% Pb and a sample at a water temperature of 15°C, the Hv was 44 to 53, and few shots reached Hv=50, making it impossible to produce a desirable shot in large quantities.

Due to its low hardness, it was not suitable for use as a zinc shot for blast shots.

Claims (1)

[Claims] 1. A blast shot characterized by using a zinc alloy consisting of 0.03 to 15% Pb, 0.04 to 2.0% Fe, and the remaining zinc and impurities. 2. A method for producing a blast shot, which comprises dropping a molten zinc alloy consisting of 0.03 to 15% Pb, 0.04 to 2.0% Fe, remaining zinc and impurities into water at a temperature of 20°C or less to form shots.