JPH081685A - Casting method using vanishing model - Google Patents

Abstract

(57) [Summary] [Purpose] In a casting method in which casting is performed using a model that disappears when heated, harmful gas generated during casting and during mold release is prevented from being released into the atmosphere, and a foul odor is generated. It protects the environment and improves the quality of castings. [Structure] A vanishing model 4 that disappears by heating is cast in a molding frame 5 with molding sand 6, and the surface of the molding sand 6 is hermetically covered with a non-permeable sheet 8, and then a molten metal 7 is cast. The gas generated at the time of charging is forcibly sucked by the suction means 10 to be guided to the exhaust pipe 11, further passed through the purifying device 12 to be purified, and then released into the atmosphere.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting method using a vanishing model in which casting is performed using a model that vanishes by heating.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 2, a casting method using a vanishing model has a model portion 1 having the same size and shape as a cast product by using a foamed resin such as polystyrene foam that disappears when heated. Then, a vanishing model 4 having a weir 2 and a sprue 3 continuous to the model portion 1 is formed, and the vanishing model 4 is molded in a molding frame 5 with molding sand 6, and then the molten metal 7 is poured from the top of the sprue 3. Is injected, whereby the vanishing model 4 is burnt and vanishing, and the model portion 1, the weir 2 and the sprue 3 are replaced with the molten metal 7 to perform casting.

However, according to the conventional casting method, the pyrolysis gas generated by the combustion disappearance of the foamed resin such as the model portion 1, the weir 2 and the sprue 3 remains unpurified in the atmosphere from the surface of the casting sand 6. At the same time, the harmful decomposition products remaining on the foundry sand 6 by being burned are burned and released into the atmosphere when the mold is released.

The pyrolyzed gas depends on the kind of metal and the pouring temperature, but in addition to CO, CnHn, etc.,
Since components such as benzene, toluene, and styrene are contained, the conventional casting method causes harmful components such as CO and CH to be emitted into the atmosphere in an unpurified state, giving off an offensive odor. It has the drawback of deteriorating the environment.

If the shape of the model portion 1 is complicated, the molding pressure of the molding sand 6 on the surface of the model portion 1 varies, and sufficient molding cannot be expected. For this reason, casting defects may occur, or the casting surface may become rough and the quality of the cast product may deteriorate. Therefore, in the conventional casting method, a relatively large feeder (not shown) is formed so as to suppress the deterioration of quality as much as possible. However, when combustion of the disappearance model 4 disappears, a large amount of pyrolysis gas is directly discharged into the atmosphere in an unpurified state, further increasing the inconvenience of giving off a strange odor and deteriorating the environment. Become.

[0006]

The problems to be solved are that harmful gas generated at the time of casting and unmolding is discharged into the atmosphere to give off a foul odor and deteriorate the environment, and the molding pressure varies. The point is that the quality of the cast product is deteriorated.

[0007]

Means for Solving the Problems According to the present invention, a disappearing model that disappears by heating is cast in a molding sand with molding sand, and the surface of the molding sand is covered with a non-permeable sheet,
The suction means is operated to suck the air in the flask, and the gas generated at the time of casting the molten metal is forcibly sucked by the suction means, and the sucked gas is discharged from the suction means to the exhaust system. It is characterized in that it is purified through a purification device connected to the system and then released into the atmosphere.By purifying the harmful gas generated during casting and releasing it into the atmosphere, the odor is eliminated and the environment is protected. Achieved the purpose of improving quality.

[0008]

According to the present invention, the pyrolysis gas generated by the combustion disappearance of the extinction model is forcibly sucked by the suction means, so that it is not discharged from the surface of the foundry sand to the atmosphere. Further, the sucked harmful gas is guided to the exhaust system, purified by the purifying device, and then released to the atmosphere, so that the bad odor can be eliminated and the environment can be protected. Moreover, when the suction means is operated during the molding sand molding, the molding sand packing density is increased due to the discharge of the air in the molding frame, and it is possible to eliminate the variation in the molding sand molding pressure with respect to the surface of the disappearing model. Therefore, even if the shape of the model is complicated, it is possible to expect sufficient embedding.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the same or corresponding parts as those of the conventional example described with reference to FIG. FIG. 1 shows a casting apparatus applied to the practice of the present invention. In this figure, a disappearing model 4 is formed of a foamed resin such as expanded polystyrene that disappears when heated, and has a model portion 1 of the same size and shape as a cast product, and a weir 2 and a spout 3 continuous to the model portion 1. have. This vanishing model 4 is molded by a molding sand 6 in a molding frame 5, and a non-breathable sheet 8 such as a synthetic resin sheet is used in the middle of the molding to mold the molding sand 6
The entire surface and the inner surface of the casting frame 5 are airtightly covered to block the ventilation to the molding sand 6, and then the molding sand 6 is also molded on the upper side of the non-permeable sheet 8. It should be noted that the entire surface of the foundry sand 6 may be airtightly covered with the non-breathable sheet 8 after completion of the molding.

On the other hand, the inlet of the intake pipe 9 is connected through the lower part of the casting frame 5, and the outlet of the intake pipe 9 is connected to the inlet of the intake means 10 composed of a vacuum pump. An exhaust pipe 11 is connected to the outlet of the intake means 10, and the exhaust pipe 1
The outlet of No. 1 is opened to the purification means 12 provided with a water tank, for example.

In the above structure, the molten metal 7 is injected from the top of the gate 3 while the intake means 10 is operating. As a result, the vanishing model 4 burns and vanishes, and the model portion 1, the weir 2 and the gate 3 are replaced with the molten metal 7. The pyrolysis gas generated by the combustion disappearance of the disappearance model 4 is forcibly sucked by the intake means 10, and therefore is not discharged from the surface of the casting sand 6 into the atmosphere. The harmful gas sucked by the intake means 10 is ejected through the exhaust pipe 11 into the purifying device 12, that is, into the water, and is mixed with the water and discharged. The inhaled pyrolysis gas contains multiple types of harmful components as described above, but these harmful components are dissolved in water and collected, so there is no concern about air pollution by eliminating foul odors. Without, it can protect the environment. The water discharge passage of the purifier 12 is, of course, provided with an opening / closing valve (not shown).

On the other hand, even after the pouring is completed, by continuing the operation of the suction means 10 for at least about 10 minutes to continue sucking air, it is possible to prevent the pyrolysis products from adhering to and remaining on the casting sand 6. Therefore, it is possible to protect the environment by preventing environmental pollution due to combustion of the pyrolysis products at the time of unmolding.

On the other hand, the entire surface of the casting sand 6 and the inner surface of the casting frame 5 are air-tightly covered with a non-breathable sheet 8 such as a synthetic resin sheet in the course of the molding, so that the casting sand 6 is ventilated. When the suction means 10 is operated between the time of shutting off and the injection of the molten metal 7, the mold sand packing density of the molding sand 6 becomes high due to the discharge of the air in the casting mold 5, and the molding sand for the surface of the disappearing model 4 It is possible to eliminate the variation in the molding pressure of 6. As a result, even if the shape of the model part 1 is complicated, sufficient mold filling can be expected, so that it is possible to suppress the occurrence of casting defects and to perform casting with a fine-grained casting surface, which improves the quality of cast products. Can be made.

[0014]

As described above, according to the present invention,
Since the harmful gas discharged from the intake means is introduced from the exhaust system to the purifying device to be purified and then released to the atmosphere, the bad odor can be eliminated and the environment can be protected. In addition, by eliminating the variation in the molding pressure of the molding sand against the surface of the disappeared model and performing sufficient molding even if the shape of the model is complicated, the occurrence of casting defects is suppressed and a fine casting surface is obtained. Casting can be performed to improve the quality of the cast product.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an example of a casting apparatus applied to the practice of the present invention.

FIG. 2 is a longitudinal sectional view of a casting apparatus applied to a conventional atmospheric casting method.

[Explanation of symbols]

 1 Disappearance model 5 Casting frame 6 Foundry sand 7 Molten metal 8 Non-breathable sheet 10 Intake means 11 Exhaust pipe 12 Purification means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ryoichi Miyuki 1-1-1, Nakanomiya Oike, Hirakata City, Osaka Prefecture Kubota Hirakata Factory

Claims (1)

[Claims] 1. A vanishing model that disappears when heated is cast in a casting mold with molding sand, the surface of the casting sand is covered with a non-permeable sheet, and then suction means is operated to move the inside of the casting mold. While sucking the air, the gas generated during the casting of the molten metal is forcibly sucked by the suction means, the sucked gas is discharged from the suction means to the exhaust system, and purified through a purifying device connected to the exhaust system. A casting method using a vanishing model characterized by releasing into the atmosphere.