JP3131790B2 - Green mold for casting and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a green mold for castings and a method for producing the same.

[0002]

2. Description of the Related Art Molds that are most widely used in the production of castings are often used in a green mold that is frequently used as a main mold for forming the outside of the casting and a core that is used to form a hollow portion of the casting. There is a self-hardening mold.

[0003] Self-hardening molds are generally made of inorganic substances such as cement and water glass, or organic substances such as drying oil and thermosetting resin, as binders, in addition to sand such as silica sand.
As a special method, there is a method in which sorbitol, a water-soluble metal compound and water are added and cured as introduced in JP-B-51-46482.

[0004] However, the main mold often does not require a particularly high hardness, and a self-hardening sand mold having a high hardness has a long working time for hardening before use, which hinders the work, and causes a problem such as grinding after use. Due to the need for reprocessing, self-hardening molds are rarely used for main molds that are more demanding for inexpensiveness and simplicity, and simpler green molds are often used.

[0005] The green mold is the simplest main mold used for making a casting of a machine used for an automobile or the like, and is a commonly used mold. It was used with the addition of water, but at present it is often composed of aggregates such as silica sand, clay, water and additives.

[0006] A green mold is widely used as a main mold because (1) a green mold is immediately taken out of a molded mold, a core is put in, and an upper mold and a lower mold are matched. (2) The casting can be taken out relatively easily, (3) The broken mold sand can be used repeatedly, and the regeneration treatment can be easily performed, (4)
This is because the material cost of the mold is low and no toxic gas is generated.

[0007]

However, although the conventional green mold has the above advantages, on the other hand, (1) the mold and the inner surface after green molding are unstable, and (2) The strength of the green mold tends to be remarkably reduced during drying, (3) Sand is easily entangled during pouring, etc. It has been expected to improve the green mold and its manufacturing method as much as possible.

[0008]

Means for Solving the Problems In order to solve the above-mentioned various problems, the present inventors have studied in detail the relationship between a green mold, additives in a manufacturing process thereof and a casting obtained.

As a result, during the green manufacturing process, certain sugar alcohols, namely erythritol, pentaerythritol, xylitol, mannitol, reduced maltose, reduced lactose, reduced starch hydrolysates, reduced xylo-oligosaccharides, By adding one or a mixture of two or more of the selected sugar alcohols to produce a green mold, the water content of the mold is low, and despite the low compactability,
The present invention succeeded in obtaining a casting in which sand biting hardly occurs and the casting surface was remarkably beautiful, and the present invention was completed.

That is, the present invention firstly provides erythritol,
Pentaerythritol, xylitol, mannitol,
It is a raw casting mold containing one or a mixture of two or more selected from the group consisting of reduced maltose, reduced lactose, reduced starch hydrolyzate, and reduced xylo-oligosaccharide.

Secondly, one or more selected from the group consisting of erythritol, pentaerythritol, xylitol, mannitol, reduced maltose, reduced lactose, reduced starch hydrolyzate, and reduced xylo-oligosaccharide during the production process of the green mold. A method for producing a green mold for a casting, characterized by producing the mixture by adding a mixture of

Third, one or more selected from the group consisting of erythritol, pentaerythritol, xylitol, mannitol, reduced maltose, reduced lactose, reduced starch hydrolyzate, and reduced xylo-oligosaccharide during the production process of the green mold. A mixture of 0.1 to 7.0% by weight to produce a green mold for casting.

Fourth, one or more selected from the group consisting of erythritol, pentaerythritol, xylitol, mannitol, reduced maltose, reduced lactose, reduced starch hydrolyzate, and reduced xylo-oligosaccharide during the production process of the green mold. Was added in an amount of 0.1 to 7.0% by weight, and aggregate, water,
And a method for producing a green mold for casting, characterized by comprising a clay.

The raw material of one or a mixture of two or more selected from the group consisting of erythritol, pentaerythritol, xylitol, mannitol, reduced maltose, reduced lactose, reduced starch hydrolyzate, reduced xylo-oligosaccharide used in the present invention is as follows: It is not particularly necessary to limit the quality, such as its purity, as long as the above components are the main components as long as the unreduced substances are contained in a large amount or an impurity component that generates gas is not contained. There is no need to add further detailed restrictions.

[0015] In addition, the state is, aqueous solution, powder, granules,
Any of the lumps can be used, but in the case of using the sugar alcohol, it is necessary to uniformly mix with the bentonite or aggregate within a relatively short time,
Most preferably, the aqueous solution has a concentration of about 70%.

In practicing the present invention, erythritol,
Pentaerythritol, xylitol, mannitol,
One or a mixture of two or more selected from the group consisting of reduced maltose, reduced lactose, reduced starch hydrolyzate, and reduced xylo-oligosaccharides is inexpensive in addition to the reason that the effects of the present invention are sufficiently exhibited. The sand and sand are easy to regenerate,
In order not to lose the original characteristics of the raw type such as no gas containing sulfur or nitrogen or generation of toxic gas, it may be added in the range of 0.1 to 7% by weight based on the weight of the raw type. preferable.

Although this value is not particularly critical,
When the addition amount is less than 0.1% by weight, the effects of the present invention, such as a decrease in the frequency of sand biting and surface stability, are often not sufficiently obtained. When added, the increase in the amount of addition may not be accompanied by an increase in the effect, so it is economically insignificant. In addition, when the amount is extremely large, the wet strength of the raw type can withstand use. It is not preferred because it may be reduced to an unacceptable level.

In practicing the present invention, there is no need to impose any restrictions on the types and amounts of other mold components used, which are different from the ranges used during normal green mold production. 0.1 to 7% by weight of the additive
When used, a material mixed with about 100 parts by weight of sand, about 7 parts by weight of clay, and about 5 parts by weight of water is advantageously used.

In the present invention, not only mountain sand, but also river sand, sand collected from the beach, and quartz sand can be used, and the sand can be used even if it is not necessarily new sand. It may be so-called return sand.

As the clay used in the present invention, all ordinary clays for green mold production can be adopted, and examples thereof include frog-eye clay, kibushi clay, bentonite and kaolin.

Further, in carrying out the present invention, it is arbitrarily possible to use various additives conventionally used, for example, coal powder, starch and the like. In some cases, a synergistic effect can be expected.

[0022]

EXAMPLES The content of the present invention will be described more specifically with reference to the following examples, but the present invention is not limited to the following examples.

[0023]

Example 1 As a sand, 87.0 parts by weight of Kashima No. 6 silica sand,
6.5 parts by weight of bentonite (volclay having a methylene blue adsorption amount of 45 to 50 ml / 0.5 g by sodium pyrophosphate method) as a clay, 2.5 parts by weight of coal powder [Asahi Coke Co., Ltd., Seacol 15] as other additives and A raw material containing 1.0 part by weight of α-starch [manufactured by Nippon Shokuhin Kako Co., Ltd., Ulster (B)] was kneaded for 2 minutes.

Then, 2.0 parts by weight of water,
Amalti [Name of reduced maltose manufactured by Towa Chemical Industry Co., Ltd.]
After adding 1.0 part by weight and setting this as Invention Zone 1, kneading was further performed for 15 minutes to obtain a green mold of the product of the present invention.

In addition, 2.0 parts by weight of water,
1.0 part by weight of PO-40 [reduced starch hydrolyzate manufactured by Towa Kasei Kogyo Co., Ltd.] was added thereto, and this was designated as Invention Zone 2. Then, the mixture was kneaded for another 15 minutes, molded and molded to obtain the product of the present invention. I got the mold.

The above-mentioned material was used as a control group 1 using 2.5 parts by weight of water, and kneaded and molded for 15 minutes in the same manner as in each invention section to obtain a green mold of a control product. Was.

Table 1 shows the proportions of Invention Section 1, Invention Section 2 and Control Section 1.

[0028]

[Table 1]

The same kneaded product before molding as the three types of green molds obtained above was used for each section using a compacting machine with a test piece (a cylindrical frame having an inner diameter of 50 mm and a length of 150 mm) specified in JIS-Z2603. Eight raw test pieces were prepared.

For Invention Zone 1, Invention Zone 2, and Control Zone 1,
Using the kneaded product before molding, the water content was measured according to JIS-Z2605, and the coercive pressure was measured according to JIS-Z2604. The surface stability and compactability were determined using the green casting test pieces according to the Japan Casting Association Tokai Branch Test Method. , Respectively.

In the measurement, the water content and compactability of the kneaded product under each condition immediately before molding were determined.
Was measured.

Further, regarding the coercive pressure and the surface stability,
The measurement was performed immediately after molding, 1 hour after molding, 3 hours after molding, and 24 hours after molding.

Table 2 shows the measurement results of water content and compactability immediately before molding, and Table 3 shows the elapsed time, coercive pressure and surface stability after molding.

In Table 3, the unit of the coercive pressure is kg / cm ² ,
The surface stability was expressed in%.

[0035]

[Table 2]

[0036]

[Table 3]

Tables 2 and 3 show that the green mold of the present invention to which the reduced maltose or the reduced starch hydrolyzate was added was superior to the green mold of the control group in both the pressure resistance and the surface stability after molding. It is clear that.

[0038]

Example 2 200 parts by weight of Mikawa No. 6 silica sand as sand and bentonite as viscosity (Volclay with methylene blue adsorption of 45 to 50 ml / 0.5 g by sodium pyrophosphate method)
The material containing 14 parts by weight was kneaded for 2 minutes.

Then, as shown in Table 4, the ratio of water and Amalti (name of reduced maltose manufactured by Towa Kasei Kogyo Co., Ltd.) solution was changed to the raw material and added to the material, and the invention zone 3 to the invention zone 6 were added. And as shown in Table 5, water and mil hen [Towa Chemical Industry
[Name of reduced lactose manufactured by Co., Ltd.] The ratio of the solution to the invention was changed to be added to make invention zone 7 to invention zone 10, and as shown in Table 6, the ratio of water and erythritol was changed to add the invention zone. After setting the invention section to the invention section 14, each invention section was further kneaded for 15 minutes and molded to obtain a green mold of the product of the present invention.

Each of the sugar alcohols was used as a 70% aqueous solution.

Further, the above-mentioned material, which was obtained by using 3.3 parts by weight of water, was used as a control group 2 and kneaded and molded for 15 minutes in the same manner as in each invention section to obtain a green mold of a control product. Was.

[0042]

[Table 4]

[0043]

[Table 5]

[0044]

[Table 6]

The same kneaded product before molding as the green mold of each section obtained above was compacted using a compacting machine with a test piece (a cylindrical frame having an inner diameter of 50 mm and a length of 150 mm) specified in JIS-Z2603.
Eleven raw test pieces were prepared for each section.

For each section, the moisture and compactability were measured using the kneaded product before molding.
The measurement was performed using a test piece after molding.
S-Z2605: moisture, JIS-Z2604: wet strength, Japan Foundry Association Tokai Branch test method: surface stability and compactability, JIS-Z2603
, The packing density was measured by the Japan Casting Association Tokai Branch Test Method, and the explosion heat crack initiation time was measured by the Tanji Method.

In the measurement, the water content and compactability of the kneaded product under each condition were measured immediately before the molding.
Was measured.

As for the coercive pressure and the surface stability,
The measurement was performed immediately after molding, 1 hour after molding, 3 hours after molding, and 24 hours after molding.

Table 7 shows the measurement results of the invention sections to which the Amalti solution was added (invention section 3 to invention section 6), and the measurement results of the invention section to which the milchen solution was added (invention section 7 to invention section 10). 8, the invention zone to which erythritol was added (invention zone 11
Table 9 shows the measurement results of the invention group 14), and Table 10 shows the measurement results of the control group 2).

[0050]

[Table 7]

[0051]

[Table 8]

[0052]

[Table 9]

[0053]

[Table 10]

From Tables 7 to 10, it can be seen that the green mold of the invention using reduced maltose, reduced lactose or erythritol has a relatively high air permeability, despite the fact that the compactability does not become extremely large. After wet strength, surface stability,
It is clear that the explosion heat crack initiation time is superior to that of the control section 2.

[0055]

According to the present invention, since the mold and the inner surface after green molding are stable, irregularities are hardly generated on the surface of the casting.
In addition, the strength of the green mold is not significantly reduced during drying, and sand is hardly caught during pouring.

──────────────────────────────────────────────────続 き Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B22C 1/00-3/00

Claims (4)

(57) [Claims] 1. A composition comprising one or a mixture of two or more selected from the group consisting of erythritol, pentaerythritol, xylitol, mannitol, reduced maltose, reduced lactose, reduced starch hydrolyzate, and reduced xylo-oligosaccharide.
Raw mold for casting. 2. An erythritol,
Pentaerythritol, xylitol, mannitol,
A method for producing a green mold for casting, characterized by adding one or a mixture of two or more selected from the group consisting of reduced maltose, reduced lactose, reduced starch hydrolyzate, and reduced xylo-oligosaccharide. 3. An erythritol,
Pentaerythritol, xylitol, mannitol,
One or more mixtures selected from the group consisting of reduced maltose, reduced lactose, reduced starch hydrolysates, and reduced xylo-oligosaccharides are added in an amount of 0.1 to 7.0% by weight based on the weight of the raw mold. A method for producing a green mold for castings. 4. An erythritol,
Pentaerythritol, xylitol, mannitol,
One or more mixtures selected from the group consisting of reduced maltose, reduced lactose, reduced starch hydrolyzate, and reduced xylo-oligosaccharides are added in an amount of 0.1 to 7.0% by weight based on the weight of the raw mold ,
A method for producing a green mold for casting, characterized by comprising an aggregate, water and clay.