JPS63177939A - Additive for casting sand mold - Google Patents

Abstract

PURPOSE:To eliminate contamination in work environment caused by dusts and to improve the workability by using composition containing mineral oil and carbonic raw material at the specific ratio as an additive for casting sand mold. CONSTITUTION:As the additive used for shaping the casting sand mold, the composition containing 10-90wt.% mineral oil and 90-10wt.% carbonic raw material is used. As the mineral oil, aromatic series mineral oil having >=200 deg.C boiling point, especially aromatic series mineral oil having >=300 deg.C is desirable to use. Further, the carbonic raw material is desirable to contain >=70wt.% of fine powdered material having <=200 mesh grain size and especially lowly- caking coal and mixing material of this lowly-caking coal with asphalt containing >=30% volatile component in dry ash free base and >=80% fixed carbon and having >=5 free swelling index is desirable to use.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an additive for foundry sand molds that is added to foundry sand used for forming foundry sand molds, and more specifically, the present invention relates to an additive for foundry sand molds that is added to foundry sand used for forming foundry sand molds. The present invention relates to an additive for foundry sand molds that can improve workability and does not cause deterioration in quality of product casting surface even after repeated use.

[Prior art and its problems] The foundry sand that forms the foundry sand mold contains sand, water, bentonite,
It is made by blending starch, carbon material, etc. in appropriate proportions.

Here, the carbon material is an indispensable additive for improving casting surface quality, preventing burning between the molten metal and the sand mold, and preventing casting scratches caused by expansion of the sand.

In other words, when no carbon material is added, a rapid reaction occurs between the silica sand and the surface of the oxidized molten iron, and this reaction produces a type of molten iron silicate (Fayalite, 2F).
eO・5i02) is generated. It is known that this iron silicate penetrates between the particles on the mold surface, causing sand to adhere to the surface, resulting in poor casting surface.

On the other hand, foundry sand is required to have stable physical properties such as air permeability, compressive strength, surface stability, and compactability.

Coal powder has been commonly used as a carbon material that meets these requirements for a long time.

However, when coal powder is used as it is.

■It is difficult to handle because it easily scatters, and for example, automatic weighing is difficult and work efficiency is poor.

■ The working environment is significantly deteriorated due to cross-wires in the casting manufacturing process, dust from mold breakage, etc.; ■ Repeated use causes ash to accumulate in the foundry sand, increasing dust, and as a result,
It contaminates the foundry sand, which reduces the quality of the casting surface of the resulting cast products. ■The generation of smoke and toxic gas (CO gas) is concentrated during pouring, moving, and mold breaking during the casting manufacturing process. 1. There is a risk of harming the health of workers.

There were various problems such as.

Therefore, in order to solve these problems, the use of coal tar, pitch, natural or artificial asphalt, various bitumens, various oils, etc. as substitutes for coal powder is being considered.

The reality is that none of them has achieved satisfactory performance.

[Objective of the Invention] The object of the present invention is to solve various problems associated with coal powder, eliminate contamination of the working environment with dust, improve workability, and improve casting surface even after repeated use. An object of the present invention is to provide an additive for foundry sand molds that does not cause a decrease in quality.

[Means for achieving the above purpose 1 This invention has been made based on the above circumstances.

In order to achieve the above object, the inventor has conducted extensive studies and found that when a composition containing mineral oil and carbonaceous raw material in a specific ratio is used as an additive for foundry sand molds, it is difficult to work with dust. The inventors have arrived at this invention by discovering that there is no environmental pollution, that automatic weighing is facilitated, improving workability, and that there is little contamination of foundry sand when used repeatedly.

That is, the outline of the present invention for achieving the above object is as follows: 10-80% by weight of mineral oil and 90-10% by weight of carbonaceous raw material.
This is an additive for foundry sand molds, characterized by containing the following.

The mineral oil includes aromatic mineral oil, paraffinic mineral oil,
Any naphthenic mineral oil or a mixture thereof can be used, but with 5% by weight of aromatic volatile components.
As mentioned above, those containing preferably 30% by weight or more can be suitably used.

Among these, aromatic mineral oils with a boiling point of 200°C or higher are preferred, and aromatic mineral oils with a boiling point of 300°C or higher are particularly preferred.

If the aromatic volatile component contained in the mineral oil is 5% by weight ungrooved, good casting surface quality may not be obtained.

If the boiling point of the mineral oil is less than 200° C., for example, smoke and odor may become significant during pouring, which may lead to deterioration of the working environment.

Examples of the carbonaceous raw material include coal, graphite, coke, pitch coke, and asphalt. These may be used alone or in combination of two or more.

Among these, it is preferable that the content of volatile components on an anhydrous and ash-free basis is 30% or more, and the fixed carbon content is 80% or more.
% or more and has a Button index of 5 or more, and a mixture of this weakly caking coal and asphalt. If the volatile components contained in the carbonaceous raw material are less than 30% (on an anhydrous and ash-free basis), the casting surface quality may deteriorate.

Furthermore, in this invention, the carbonaceous raw material has a particle size of 20
It is preferable that the carbonaceous raw material contains 70% by weight or more of fine powder with a particle size of 0 mesh or less.If the carbonaceous raw material contains more than 30% by weight of powder with a particle size of 200 mesh or more, uniform mixing with the mineral oil is not possible. It can be difficult, resulting in
It may be difficult to prepare foundry sand with uniform physical properties.

In this invention, a composition is prepared by mixing the mineral oil and carbonaceous raw material.

The blending ratio of the mineral oil in the composition is usually 1, 10
-80% by weight, preferably 30-70% by weight, particularly preferably 40-60% by weight, and the blending ratio of the carbonaceous raw material is usually 80-10% by weight, preferably 70-3% by weight.
0% by weight, particularly preferably 60-40% by weight.

If the blending ratio of the mineral oil is less than 10% by weight, repeated use of the additive for foundry sand molds of the present invention may cause ash to accumulate in the foundry sand, leading to deterioration in casting surface quality. . On the other hand, if the blending ratio of the mineral oil exceeds 90% by weight, smoke and odor may become intense.

To prepare foundry sand using the foundry sand mold additive of this invention, for example, sand, a binder, a starchy additive, and water are kneaded in appropriate proportions together with the foundry sand mold additive of this invention. do it.

Here, as the sand, any sand commonly used as foundry sand can be used without limitation, and examples thereof include mountain sand, semi-synthetic sand, and synthetic sand.

Mountain sand is naturally occurring and has a viscosity of at least 2%.
For example, Noma sand in Aichi prefecture, Kawachi sand in Osaka prefecture, Shima sand in Mie prefecture, Matsue sand in Shimane prefecture, etc.
Other examples include Ota sand from Fukushima Prefecture, Enshu sand, and Genkai sand. Preferred are Enshu sand, Genkai sand, and the like.

Examples of semi-synthetic sand include sand made by gJ by appropriately blending the mountain sand with silica sand, a binder, and additives.
Examples of synthetic sand include those made by blending raw material sand such as silica sand with a binder and additives without using mountain sand at all. The raw material sand used for this synthetic sand includes natural silica sand such as gyrome silica sand, beach sand and river sand, artificial silica sand such as silica artificial silica sand, conical silicic acid and weathered silicic acid, zircon silicic acid, oripin sand, and chromite sand. Examples include.

Examples of the binder include wood tablet clay, bentonite, montmorillonite, and kaolin.

Examples of the starchy additive include dextrin and starch.

A fibrous additive may be added to the foundry sand mold formed using the foundry sand mold additive according to the present invention, and such fibrous additives include Japanese paper, rice husk, and the like.

An example of the mixing ratio of each component in a foundry sand mold formed using the additive for foundry sand molds according to the present invention is as follows: acid 10
0 parts, bentonite 10 parts, starch 1 part, water 3 parts, and 1 to 2 parts of the foundry sand mold additive according to the present invention. Furthermore, when the blending ratio of mineral oil in the additive for foundry sand molds of the present invention is high, a surfactant may be appropriately used in preparing the foundry sand.

A foundry sand mold formed using the foundry sand mold additive according to the present invention is suitable for producing castings such as steel castings, iron castings, copper alloy castings, aluminum alloy castings, magnesium alloy castings, zinc alloy castings, etc.

When manufacturing such castings, the additive for foundry sand molds of the present invention significantly improves the working environment by preventing the fine powder of carbonaceous raw materials from being scattered by the liquid mineral oil, and also prevents the mineral oil from being dispersed by the heat of the molten metal. The volatile components in the carbonaceous raw material are gasified to form a gas film between the mold and the molten metal, thereby improving the casting surface and preventing burning.

The additive for foundry sand molds according to the invention can be applied not only to ordinary molds but also to special molds such as shell molds and carbon dioxide molds. .

[Effects of the Invention] The additive for foundry sand molds of the present invention is made by mixing fine powder of carbonaceous raw material and mineral oil in a specific ratio.

Therefore, according to this invention, (1) there is no concern that the working environment will be degraded by scattering of fine powder, unlike with conventional additives for foundry sand molds that use only coal powder, and (2) automatic metering is possible. (3) When molding sand containing the additive for foundry sand molds of the present invention is used after refilling, less ash is deposited in the molding sand. As a result, there is no contamination of the foundry sand.
There is no deterioration of the casting surface when molding sand is repeatedly used, and (4) compared to conventional additives for molding sand molds that use only coal powder, the additives improve molding sand by reducing fine powder and ash content, which absorb water. It is possible to reduce the amount of water to be mixed and also reduce the amount of bentonite and starch used as binders in the same proportion, so the air permeability and fluidity of foundry sand can be improved. An additive for foundry sand molds having properties can be provided.

[Example] Next, Examples and Comparative Examples of the present invention will be shown, and the additive for foundry sand molds of the present invention will be explained in more detail.

(Example 1) Aromatic mineral oil [Product name: rDiana Oil E-
100J: manufactured by Idemitsu Kosan ■] and coal powder [product name:
Seacoal 8": made by Asahi Coke ■) using mineral oil 50%
An additive for foundry sand molds was prepared with a blending ratio of 50% by weight and 50% by weight of coal powder.

Next, using this foundry sand mold additive, foundry sand having the following blending ratio was prepared.

Enshu sand, ψken...100 parts bentonite ass number 10 parts starch...1 part water...φ...-3 parts additive for foundry sand mold, fist, 1 A sand mold was formed using the foundry sand 20. 4 kg of casting material (equivalent to FC-20) was cast into this sand mold at a casting temperature of 1350°C, and then the mold was barracked.
The foundry sand was regenerated by replenishing only moisture to the foundry sand. A sand mold was formed using the recycled foundry sand 20, and the casting material was cast under the same conditions as described above. The same operation was repeated 10 times, and the moldability of the molding sand and the casting surface quality of the product were evaluated. We conducted an evaluation.

The results are shown in Table 1.

As is clear from Table 1, in the molding sand containing the foundry sand mold additive of the present invention, no deterioration in moldability or casting surface quality of the product was observed even after repeated recycling.

(Comparative Example 1) In Example 1, 50% by weight of mineral oil and 5% by weight of coal powder were added.
Aromatic mineral oil [Product name: 1ana Oil E-100J:
The moldability of the molding sand and the quality of the casting surface of the product were evaluated in the same manner as in Example 1, except that the molding sand (manufactured by Idemitsu Kosan) was used.

The results are shown in Table 1.

As is clear from Table 1, when only aromatic mineral oil was used, the quality of the casting surface of the product deteriorated as the foundry sand was repeatedly recycled.

(Comparative Example 2) In Example 1, 50% by weight of mineral oil and 5% by weight of coal powder were added.
Same as Example 1 except that coal powder [trade name: "Secoal 8" manufactured by Asahi Coke ■] was used instead of the foundry sand mold additive consisting of 0% by weight, and foundry sand was prepared at the following blending ratio. The moldability of the foundry sand and the quality of the casting surface of the product were evaluated.

Enshu Sand - 100 copies Bentonite --- 10 parts Starch...Φ...1 part Water・・・・・・・・・3 parts Coal powder・・・・・・・2 parts The results are shown in Table 1.

As is clear from Table 1, when only coal powder was used, as the foundry sand was repeatedly recycled, both the moldability of the foundry sand and the quality of the casting surface of the product decreased.

(Hereinafter, blank space) Table 1 (Example 2) In Example 1, asphalt l-[
Foundry sand was prepared in the same manner as in Example 1, except that 80/80 asphalt (manufactured by Union Oil Company) was used.

A sand mold was formed using 20 kg of the obtained foundry sand, and the moldability of the foundry sand was evaluated.
Casting material (FC-20 equivalent) 4k at a casting temperature of °C
g was cast, and the quality of the casting surface of the product, smoke and odor from the molding sand, and dust were evaluated.

The results are shown in Table 2.

As is clear from Table 2, the molding sand containing the additive for foundry sand molds of the present invention has good moldability and casting surface quality of the product, and there is little smoke and odor from the molding sand. Further, no dust from the foundry sand was observed.

(Comparative Example 3) In Example 2, aromatic mineral oil [trade name: rDiana OilE-100] was used instead of the foundry sand mold additive consisting of 50% by weight of mineral oil and 50% by weight of asphalt.
J: manufactured by Idemitsu Kosan v4] was used as in Example 2 above.
In the same manner as above, each item of the moldability of the molding sand, the quality of the casting surface of the product, the smoke and odor from the molding sand, and the dust was evaluated.

The results are shown in Table 2.

As is clear from Table 2, when only aromatic mineral oil was used, the smoke and odor from the foundry sand were severe.

(Comparative Example 4) The moldability of foundry sand was evaluated in the same manner as in Comparative Example 3 except that asphalt (fiO/80 asphalt: manufactured by Union Oil Co., Ltd.) was used in place of the aromatic mineral oil. Product casting surface quality, smoke and odor from molding sand,
Each item of dust was evaluated.

The results are shown in Table 2.

As is clear from Table 2, when only asphalt was used, the moldability of the foundry sand and the quality of the casting surface of the product were not good.

The reason for this is presumed to be that asphalt has a property of not being compatible with sand.

(Comparative Example 5) In Example 2, coal powder [trade name: "Secoal 8" manufactured by Asahi Coke ■] was used instead of the foundry sand mold additive consisting of 50% by weight of mineral oil and 50% by weight of asphalt, and the following Evaluations were made in the same manner as in Example 2, except that foundry sand was manufactured using rA at a mixing ratio of 100 to 100%, with respect to moldability of the foundry sand, casting surface quality of the product, smoke and odor from the foundry sand, and dust.

Enshu Sand・・・・・・100 copies Bentonite・Fist・10 parts Starch・・・・・・・・・1 part Tree・・・・・・・・・3 parts Coal powder dispute...φ...Part 2 The results are shown in Table 2.

As is clear from Table 2, when only one coal powder was used, the dust from the foundry sand was intense.

The evaluation method and evaluation criteria for each item are as follows.

Moldability: After putting the mixed foundry sand into the mold and hardening it, remove the mold and visually observe the formed sand mold.

Rating 5. Good (normal).

4. There is a slight omission (1 place).

3. Moderate missing parts (2 places).

2: Severe defects (3 or more places).

l...Cannot be molded.

Casting surface quality: The appearance of the cast product obtained by demolding the sand mold is visually observed after shot blasting (for 3 minutes).

Rating 5. Good (normal).

4.The area of surface unevenness is less than 5%.

3. The area of the surface unevenness is 5 to 10%.

2. Surface vXio of the surface unevenness portion ~20%.

lee surface unevenness area of 20% or more.

(However, surface irregularities are due to sand encroachment, squeezing, scooping, gas defects, burning, etc.) Smoke, odor, dust: All based on five sense evaluations.

(Hereinafter, blank space) Table 2 (Example 3) Aromatic mineral oil [Product name: rDiana Oil E-
100J: Made by Idemitsu Kosan ■] and Coal powder [Product name:
"Seacoal 8": manufactured by Asahi Coke ■] using mineral oil 7
An additive for foundry sand molds was prepared with a blending ratio of 0% by weight and 30% by weight of coal powder.

Using this foundry sand mold additive, foundry sand was prepared in the same manner as in Example 1, and a sand mold was formed.

Then, in the same manner as in Example 1, the molding properties of the foundry sand, the quality of the casting surface of the product, etc. were evaluated.

The results are shown in Table 3.

(Example 4) Aromatic mineral oil [Product name: rDiana Oil E-
100J: manufactured by Idemitsu Kosan ■] and coal powder [trade name;
Seacoal 8]: manufactured by Asahi Coke ■] using mineral oil 30
An additive for foundry sand molds was prepared with a blending ratio of 1% by weight and 70% by weight of coal powder.

Using this foundry sand mold additive, foundry sand was prepared in the same manner as in Example 1, and a sand mold was formed.

Then, the moldability of the foundry sand was evaluated in the same manner as in Example 1, and the moldability of the foundry sand, the casting surface quality of the product, etc. were evaluated in the same manner as in Example 1.

The results are shown in Table 3.

(Hereafter, margin) Table 3

Claims (4)

[Claims] (1) An additive for foundry sand molds, characterized by containing 10 to 90% by weight of mineral oil and 90 to 10% by weight of carbonaceous raw material. (2) The additive for foundry sand molds according to claim 1, which contains 70% by weight or more of fine powder with a particle size of 200 mesh or less in the carbonaceous raw material. (3) The additive for foundry sand molds according to claim 1 or 2, wherein the volatile content in the carbonaceous raw material is 30% or more (on an anhydrous and ash-free basis). (4) The additive for foundry sand molds according to claim 1, 2, or 3, wherein the mineral oil is an aromatic mineral oil with a boiling point of 200° C. or higher.