JPH05237627A - Lost foam pattern casting method - Google Patents

Abstract

PURPOSE:To prevent the occurrence of shortage of molten metal for casting and cold shut by pouring and filling up the molten metal into a pouring box placed above dry sand, pressurizing molten metal surface and top-pouring the molten metal into an inner part of a lost foam pattern to increase the molten metal pressure at the initial stage of casting. CONSTITUTION:The lost foam pattern 2 is embedded in the dry sand 1 and the pouring box 3 is placed above the dry sand 1. A stopper 4 is inserted in the pouring box 3 and the molten metal 7 is filled up into the pouring box 3. A chamber body 5 is engaged with the pouring box 3 and integratively combined to form a chamber. After pressurizing in the chamber by supplying compressed air into the chamber body 5, the stopper 4 is pulled out from the pouring box 3 and then, the molten metal 7 is top-poured into the inner part of the lost foam pattern 2 at high flow rate and the lost foam pattern 2 is replaced into the molten metal 7. As molten metal pressure at the initial stage of casting is higher than decomposed gas pressure in the lost foam pattern 2 generated an the initial stage of casting, back flow of the cast molten iron hardly occurs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved disappearance model casting method, and more particularly, to an extinction model casting method for preventing the occurrence of casting defects due to the decomposition gas pressure of the disappearance model which is likely to occur in the initial stage of casting. It is about.

[0002]

2. Description of the Related Art As a mold used in the disappearance model casting method,
There is a model in which a hanging weir is placed on the sprue of a vanishing model buried in dry sand (for example, Fig. 2 of Japanese Utility Model Publication No. 3-7055).

[0003]

When vanishing model casting is performed using a conventional mold, the vanishing model is thermally decomposed by the heat of the high-temperature molten metal cast through the hanging weir, and part of it is dried sand. Although it is released through the mold to the outside of the mold, especially in the initial stage of casting, the amount of molten metal to be cast is small, and the pressure of the generated decomposition gas tends to be higher than the pressure of the molten metal. Eventually, there was a "blowback phenomenon" in which the casting melt was blown up from the hanging weir, and there was probably a danger in the casting operation. Further, there is a problem that the backflow of the molten metal may cause the molten metal to be poured into the casting mold and run out. Therefore, the present invention has been made in order to solve such a problem, and provides a vanishing model casting method capable of preventing the backflow of the molten metal which is likely to occur at the initial stage of casting.

[0004]

In the disappearance model casting method of the present invention, a molten weir is poured and filled in a hanging weir placed on the upper part of dry sand, and the molten metal surface is pressurized with compressed air, and then the molten metal is melted. It is characterized by pouring the above into the disappearance model.

[0005]

[Function] Since the molten metal pressure at the initial stage of pouring is higher than the decomposition gas pressure of the vanishing model generated at the early stage of pouring, the pouring molten metal flows into the inside of the vanishing model from the hanging weir at a high flow rate. Does not cause backflow of molten metal.

[0006]

EXAMPLE A mold used in the present invention is shown in FIG. 1, in which a vanishing model 2 is embedded in a dry sand 1, a hanging weir 3 is provided on the dry sand 1, and the hanging weir 3 is detachable. A stopper 4 is fitted in, a movable chamber body 5 is provided above the latch weir 4, a lower opening is provided in the chamber body 5, and an air supply pipe 6 is connected to the side wall.

Next, the casting operation will be described. After the disappearance model 2 is embedded in the dry sand 1, the latch 3 is placed on the dry sand 1, the stopper 4 is fitted into the latch 3, and then the latch 3 is inserted.
Fill up with molten metal 7. Next, the chamber body 5 is engaged with the latch weir 3 as shown in FIG.
Are integrally joined to form a chamber, and thereafter, compressed air in the chamber body 5 is supplied from the air supply pipe 6 to pressurize the chamber, and then the stopper 4 is pulled out from the latch weir 3. Is poured into the disappearance model 2 at a high flow rate, and the disappearance model 2 is replaced with the molten metal 7. Since the molten metal pressure in the initial stage of casting is higher than the decomposition gas pressure of the vanishing model 2 that occurs in the initial stage of casting, backflow of the molten cast metal is unlikely to occur. afterwards,
The pressure inside the chamber body 5 is released, the chamber body 5 is moved to a predetermined position, the cast mold is taken out, and the mold is released to obtain a casting.

In the above-mentioned embodiment, casting was performed in the air, but even if casting is performed under pressure in an inert atmosphere, the same operation as in the above-mentioned embodiment is achieved.

[0009]

EFFECTS OF THE INVENTION According to the present invention, the molten metal is injected and filled into the weir placed on the upper part of the dry sand, and the molten metal surface is pressurized with compressed air, and then the molten metal is discharged to the inside of the disappearing model. I'll pour
The molten metal pressure at the initial stage of pouring increases, backflow of the molten pouring is less likely to occur, and the molten metal of the pouring molten metal and the molten metal boundary do not occur.

[Brief description of drawings]

FIG. 1 is a sectional view of a mold used in the present invention.

[Explanation of symbols]

 1 Dry sand 2 Disappearance model 3 Hanging weir 7 Molten metal

Claims (2)

[Claims] 1. In a vanishing model casting method in which a vanishing model is embedded in dry sand, and then molten metal is injected into the vanishing model to replace the vanishing model with the molten metal, the vanishing model is placed on top of the dry sand. A vanishing model casting method, which comprises filling and filling a molten weir with molten metal, pressurizing the molten metal surface with compressed air, and then pouring the molten metal onto the inside of the vanishing model. 2. The vanishing model casting method according to claim 1, wherein an inert gas is used instead of the compressed air.