JPS59130647A - Mold forming method - Google Patents

Abstract

PURPOSE:To dry and cure molding sand in a short time in mold forming by putting a cover member on a casting mold formed of the molding sand contg. a water soluble binder on a plate material provided with plural vent holes, and passing cold or hot compressed air to the molding sand. CONSTITUTION:A molding flask 2 is put on a pattern board 1 with a pattern and molding sand S kneaded with an aq. soln. of roasted dextrin, oxidized starch, etc. is packed and rammed in the flask. A plate material 5 having many vent holes 5 and adhered with a sheet gasket 3 is put on and the assembly is upset. A cover member 7 is put on the material 5. Cold or hot air is blown through the holes 6 and is passed through the inside of the sand S thereby drying the sand to cure. Since the molding sand is dried and cured in a short time with the small amt. of the air, productivity is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for making a mold using foundry sand mixed with a water-soluble binder.

In general, mold making methods other than green molds include shell mold method, cold box method, bardock method, CO2
Molding methods such as the method are known. However, the shell mold method uses a heated mold to thermoset the phenol resin in the shell sand to create the mold, which requires an expensive mold and generates a bad odor due to the phenol resin odor when heated. There are drawbacks. Also, cold box method,
Since the No. 1-Dox method uses harmful curing gases such as triethylamine and S02 gas for molding, it is necessary to install equipment for treating these gases and is difficult to handle. Furthermore, since the CO2 method uses water glass as a binder, discarding the sand after use causes alkali pollution, and there are other problems such as extremely poor collapsibility of the hardened mold. To this end, in recent years, a molding method using water-soluble glue as a binder has been proposed. There is a method of filling a model with molding sand and then drying and hardening the molding sand by suction. Techniques have been disclosed for filling a model and drying and hardening the foundry sand using heat radiated and dissipated from the model. However, the former method has the drawback that the molding sand mixed with a water-soluble binder is heated in advance, which causes stickiness and prevents the molding sand from filling every corner of the model. There were problems such as easy evaporation and difficulty in keeping the moisture constant.

In addition, in the case of the latter G, since it is necessary to rub the model with an expensive mold, the cost of the mold becomes high and there is an economical problem.

The present invention was made in view of these problems, and the space formed by twisting the model plate with model and the casting flask is filled with foundry sand mixed and mixed with a water-soluble binder. After,
A plate material with a plurality of ventilation holes is placed on the surface of the casting flask, and the model plate with model, casting flask, and plate material are integrated (this is turned over, and then the model plate with model is placed). After the mold is released from the molding sand, a G cover member is placed to cover the molding sand in the molding flask, and room temperature or heated compressed air is supplied to the molding sand within a month. The object of the present invention is to provide a mold making method in which the foundry sand is dried and hardened by aeration.

The present invention will be explained below based on Example Q. As shown in Figure 1, there is a mold plate (2) on the top of a wooden model board (1).
In the space Q formed by the model plate with model (1) and the flask (2), roasted dextrin 1, IJ, oxidized starch, alpha starch, starch ester, starch ether,
Foundry sand (S) mixed and kneaded with a water-soluble binder such as high amylose (hereinafter referred to as foundry sand) is packed while being compacted to a predetermined density, and the upper surface of the foundry sand is covered with molding sand. After smoothing the frame (2) so that it is approximately on the same plane as the upper surface G, as shown in Figure 2 A plate (5) having a plurality of vent holes (4) passing through the flask (5) and a vent plug (not shown) embedded therein is attached to the flask (2). When placed in an airtight manner via the upper surface ζ sheet packing (3),
These model plate with model (1), casting flask (2), and plate side (
5) is inverted to one weight, and the model plate with model (1) is released from the molding sand (S) (FIG. 2). At this time, the foundry sand is packed to a predetermined density, and the viscosity of the water-soluble binder acts between the sand particles.
) Even if it is released from the mold, the surface of the mold will not deteriorate.

Next, as shown in Fig. 4, the air supply holes (6
) is strained to cover the molding sand (IEI) in the flask 'C2), and then poured into the cover member (7) through the air supply hole (6) at room temperature. Alternatively, when heated compressed air is supplied, the compressed air is passed through the molding sand from the mold surface of the molding sand and exhausted to the outside through the ventilation hole (4). In this way, when compressed air is passed through the molding sand from the mold surface for a predetermined period of time, the moisture in the molding sand is dried and hardened in order from the mold surface, and soon the entire mold is dried and hardened ( M) is molded.

In particular, the mold surface of the foundry sand is made to have high hardness.

After that, 5) Remove the h part side (7) and the plate material (5) (Fig. 5) and overlap it with the other half of the mold, which was hardened and molded in the same manner as above, to form a pair of completed molds. It is something. Furthermore, as shown in FIG. 6, a back-up type mold bond may be used in which the ventilation time of compressed air is shortened, only the surface of the molding sand (S) is hardened, and the unhardened portion is removed. In addition, in the above embodiment, the molding sand (8
) is filled to a predetermined density while compacting, but it may also be filled to a predetermined density by blowing, squeezing, vibration, etc.

As is clear from the above explanation, according to the present invention, after the model plate with model was released from the mold, the molding sand was strained to allow room temperature or heated compressed air to pass through the mold surface. It is possible to dry and harden the mold surface of molding sand quickly and uniformly, and the amount of air consumption is reduced.Therefore, good molds can be efficiently produced, and it has the effect of helping to save energy. Furthermore, since the model board with the model may be made of wood, it has the advantage of being economically advantageous because the cost of the model is low, and the effect it has on this type of industry is significant.

[Brief explanation of the drawing]

1 to 6 are process diagrams showing an embodiment of the present invention. (1): Model plate with model (2): Cast flask (4) Double hole (5): Plate material (6): Air supply hole (7): Cover part procedure amendment (method) S. 1982 Director General of Japan Patent Office 1, Indication of Matter A'1 1982'L MvI Application No. 4470? r2, Name of the invention Mold making method 3, Person making the amendment, case and relationship Patent applicant address (residence) 4-7-23 Meieki, Nakamura-ku, Nagoya, Aichi Prefecture Shinto Kogyo in Toyota Pill Name: Shinto Kogyo Co., Ltd. April 6, 1981 (Shipping date: April 26, 1988)
5. Subject of amendment Meiji 1st

Claims (1)

[Claims] After filling the space defined by the model plate with model, the flask, and the molding sand to a predetermined density with a water-soluble binder added and kneaded, a plurality of ventilation holes are inserted into the upper surface of the flask. The plate side provided with the molding sand is placed in an airtight manner so as to cover the molding sand, and
The model plate with model, the flask and the plate material are turned over as one unit, and then the model plate with model is released from the molding sand, and then a cover member provided with an air supply hole is inserted into the flask. Cover the molding sand so as to cover it, and supply room-temperature or heated compressed air from the air supply hole to the top of the cover, allowing it to flow through the molding sand from the mold surface of the molding sand, and from the air hole. A mold making method characterized in that the molding sand is dried and hardened by exhausting the air.