JPH0337816B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] This invention relates to a foundry sand mold additive added to foundry sand used to form a foundry sand mold, and more specifically, to improve workability without contaminating the working environment with dust. The present invention relates to an additive for foundry sand molds which can be used repeatedly and which does not cause deterioration in the quality of the product casting surface even when used repeatedly. [Prior Art and its Problems] The foundry sand used to form the foundry sand mold is a mixture of sand, water, bentonite, 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 meltable iron silicate (fireite, 2FeO・SiO ₂ ). 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 it is difficult to automatically measure it, resulting in poor workability.Dust from kneading, mold breaking, etc. in the casting manufacturing process creates a problem in the working environment. With repeated use, ash will accumulate in the foundry sand and increase dust, which will contaminate the foundry sand and reduce the quality of the casting surface of the resulting foundry product. Smoke and toxic gases ( Since the generation of CO gas (CO gas) is concentrated during pouring, moving, and breaking the molds during the casting manufacturing process, various problems have arisen, including the risk of harming the health of workers. 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 object] The present 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, automatic weighing is facilitated, workability can be improved, and the foundry sand is less contaminated when used repeatedly. That is, the outline of the present invention to achieve the above object is to provide a sand mold for foundry, characterized by containing 10 to 90% by weight of mineral oil and 90 to 10% by weight of carbonaceous raw material that may contain fine powder. It is an additive. As the mineral oil, aromatic mineral oil, paraffinic mineral oil, naphthenic mineral oil, or a mixture thereof can be used, but the aromatic volatile component is 5% by weight or more, preferably 30% by weight.
Those containing the above can be suitably used.
Among these, preferred are aromatic mineral oils with a boiling point of 200°C or higher, and particularly preferred are aromatic mineral oils with a boiling point of 200°C or higher.
It is an aromatic mineral oil with a temperature of over 300℃. The aromatic volatile component contained in the mineral oil is 5
If it is less than % by weight, 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, preferable are weakly coking coals having a volatile component content of 30% or more on an anhydrous and ashless basis, a fixed carbon content of 80% or more, and a button index of 5 or more; It is a mixture of coking 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. Further, in the present invention, it is preferable that the carbonaceous raw material contains 70% by weight or more of fine powder with a particle size of 200 mesh or less. The carbonaceous raw material has a particle size
When containing more than 30% by weight of powder of 200 mesh or more, it may be difficult to mix uniformly with the mineral oil, and as a result, it becomes difficult to prepare foundry sand with uniform physical properties. Sometimes. 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 10 to 90% by weight, preferably 30 to 70% by weight, particularly preferably 40 to 60% by weight, and the blending ratio of the carbonaceous raw material is usually 90% by weight. ~10% by weight, preferably 70-30% 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, resulting in deterioration of 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. The mountain sand may be any naturally occurring sand with a viscosity of at least 2%, such as 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 prepared 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 silica sand, and weathered silica sand, zircon silica sand, olivine sand, and chromite sand. Examples include. Examples of the binder include Kibushi 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 foundry sand mold additive according to the present invention is 100 parts of sand, 10 parts of bentonite, 1 part of starch,
3 parts of water, additives 1 to 2 for foundry sand molds according to the present invention
Department. Further, when the blending ratio of mineral oil in the foundry sand mold additive of the present invention is high, a surfactant may be appropriately used in preparing the foundry sand. Foundry sand molds formed using the additive for foundry sand molds according to the present invention can be used for cast steel products, cast iron products, copper alloy castings,
aluminum alloy castings, magnesium alloy castings,
Suitable for manufacturing castings such as zinc alloy castings. When manufacturing such castings, the foundry sand mold additive of the present invention significantly improves the working environment by preventing the fine powder of the carbonaceous raw material from being scattered by the liquid mineral oil, and also reduces the heat of the molten metal. As a result, volatile components in the mineral oil and carbonaceous raw materials are gasified and a gas film is formed between the mold and the molten metal, thereby improving the casting surface and preventing burning. The foundry sand mold additive 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) unlike conventional additives for foundry sand molds that use only coal powder, there is no need to worry about the fine powder scattering and worsening the working environment; and (2) automatic metering. (3) When the foundry sand containing the foundry sand mold additive of the present invention is repeatedly used, the amount of ash deposited in the foundry sand is small. It does not contaminate the sand, and as a result, there is no deterioration of the casting surface when the foundry sand is used repeatedly. By reducing the absorbed fine powder and ash content, the amount of water added to the foundry sand can be reduced, and the amount of bentonite and starch used as binders can also be reduced at the same rate, improving the air permeability of the foundry sand. It is possible to provide additives for foundry sand molds having various properties such as being able to improve fluidity. [Example] Next, examples and comparative examples of this invention are shown,
The additive for foundry sand molds of this invention will be explained in more detail. Example 1 Aromatic mineral oil [trade name: “Diana Oil E-
100”: manufactured by Idemitsu Kosan Co., Ltd.] and coal powder [trade name;
"Seacoal 8" manufactured by Asahi Coke Co., Ltd.] was used to prepare an additive for foundry sand molds at a blending ratio of 50% by weight of mineral oil 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: 100 parts Bentonite: 10 parts Starch: 1 part Water: 3 parts Additive for foundry sand molds: 1 part A sand mold was formed using 20 kg of this foundry sand. The casting material (FC-
20 equivalent product) 4 kg was cast. Thereafter, the mold was broken out, and only water was added to the recovered foundry sand to regenerate the foundry sand. A sand mold was formed using 20 kg of recycled foundry sand, and the casting material was cast under the same conditions as above. The same operation was repeated 10 times, and the moldability of the molding sand and the quality of the casting surface of the product were evaluated. The results are shown in Table 1. As is clear from Table 1, when the foundry sand containing the foundry sand mold additive of the present invention was repeatedly recycled, no deterioration in moldability or casting surface quality of the product was observed. Comparative Example 1 In Example 1, aromatic mineral oil [trade name: "Diana Oil E-100"] was used instead of the foundry sand mold additive consisting of 50% by weight of mineral oil and 50% by weight of coal powder.
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 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, instead of the foundry sand mold additive consisting of 50% by weight of mineral oil and 50% by weight of coal powder, coal powder [trade name: "Secoal 8": Asahi Coke Co., Ltd.]
The moldability of the foundry sand and the quality of the casting surface of the product were evaluated in the same manner as in Example 1, except that a foundry sand mold was prepared using the following compounding ratio. Enshu sand: 100 parts Bentonite: 10 parts Starch: 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 molding sand was repeatedly recycled, both the moldability of the molding sand and the quality of the casting surface of the product deteriorated.

[Table] Example 2 Asphalt was used instead of coal powder in Example 1 [60/80 asphalt: manufactured by Union Oil Co., Ltd.]
Foundry sand was prepared in the same manner as in Example 1 except that the following was used. A sand mold was formed using 20 kg of the obtained foundry sand, and the moldability of the foundry sand was evaluated. Next, 4 kg of casting material (EC-20 equivalent) was cast into this sand mold at a casting temperature of 1350°C, and the casting surface quality 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: "Diana Oil E-
100": manufactured by Idemitsu Kosan Co., Ltd.] was used in the same manner as in Example 2 above, and the molding properties of the molding sand, the quality of the casting surface of the product, the smoke and odor from the molding sand, and the dust were evaluated. I did this. 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 intense. Comparative Example 4 In the same manner as Comparative Example 3, except that asphalt [60/80 asphalt: manufactured by Union Oil Co., Ltd.] was used instead of the aromatic mineral oil, moldability of molding sand and product were evaluated. The quality of the casting surface, smoke and odor from the foundry sand, and dust were evaluated. The results are shown in Table 2. As is clear from Table 2, when only asphalt was used, the moldability of the molding 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: Seacoal 8, manufactured by Asahi Coke Co., Ltd.] 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 The molding sand was prepared in the same manner as in the previous example, except that the molding sand was prepared with a blending ratio of 1 to 2. The molding properties of the molding sand, the quality of the casting surface of the product, the smoke and odor from the molding sand, and the dust were evaluated. Enshu sand: 100 parts Bentonite: 10 parts Starch: 1 part Water: 3 parts Coal powder: 2 parts The results are shown in Table 2. As is clear from Table 2, when only 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 solidifying it, remove the mold and visually observe the formed sand mold. Rating score 5...Good (normal). 4...There is a slight omission (1 place). 3...Moderate omissions (2 places). 2...Severe defects (3 or more places). 1...Unable to be molded. Casting surface quality: The appearance of the cast product obtained by breaking the sand mold is visually observed after shot blasting (for 3 minutes). Rating score 5...Good (normal). 4...The area of the surface unevenness is less than 5%. 3...The area of the surface unevenness is 5 to 10%. 2...The area of the surface unevenness is 10-20%. 1...The area of the surface unevenness is 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.

[Table] Example 3 Aromatic mineral oil [Product name: “Diana Oil E-
100”: manufactured by Idemitsu Kosan Co., Ltd.] and coal powder [trade name;
"Seacoal 8" manufactured by Asahi Coke Co., Ltd.] was used to prepare an additive for foundry sand molds at a blending ratio of 70% by weight of mineral oil 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 moldability of the foundry sand,
The cast surface quality of the product was evaluated. The results are shown in Table 3. Example 4 Aromatic mineral oil [trade name: “Diana Oil E-
100”: manufactured by Idemitsu Kosan Co., Ltd.] and coal powder [trade name;
An additive for foundry sand molds was prepared using "Seacoal 8" (manufactured by Asahi Coke Co., Ltd.) with a blending ratio of 30% by weight of mineral oil 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, in the same manner as in Example 1, the moldability of the foundry sand,
The cast surface quality of the product was evaluated. The results are shown in Table 3.

【table】

Claims (1)

[Scope of Claims] 1. An additive for foundry sand molds, characterized in that it contains 10 to 90% by weight of mineral oil and 90 to 10% by weight of a carbonaceous raw material that may contain fine powder. 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.