JPS58167052A - Casting method - Google Patents

Abstract

PURPOSE:To enable stable operation by adding a stage for sucking and expelling the air among sand grains to a full mold method. CONSTITUTION:A pattern 3 provided with a runner part 31 and a riser part 32 formed of an instantaneous burning material and sand 2 enclosing the pattern 3 are packed in a molding flask 1 which has many fine vent holes 13 on the wall surface and has an opened top surface. A shielding layer 5 which shields the sand 2 from the atmospheric air is formed on the top surface of the sand layer in the flask 1, and the air in the flask 1 is sucked through the holes 13 of the flask 1 to the outside of the flask 1 to compact the sand 2 tightly. Thereupon, molten metal is charged through the part 31, and while the pattern 3 including the part 31 and the part 32 is burned away by the high temp. of the melt, the molten metal is packed in replacement with the pattern 3. Thereafter, the suction is stopped and upon cooling and solidifying of the melt, the mold is removed and the casting is taken out.

Description

[Detailed description of the invention] The present invention relates to a casting method.

Conventionally, in many cases of casting, a space between an upper mold and a lower mold formed by compacting molding sand is filled with molten metal, and the molten metal is cooled and solidified.

In the above case, the upper and lower molds must be manufactured separately and butted together, which requires time and skill.

Therefore, the full mold method, which does not require dividing the mold and is easy to manufacture, is also being implemented. As shown in Figure 2, a model made of foamed resin (3) is buried in molding sand (2) filled in a mold (1), and the molten metal is directly poured into it without pulling out the model (3). The high heat of the molten metal burns up the model, and then fills it with molten metal to replace it.

However, in the case of the full mold method, since the strength of the foamed resin is weak, it is not possible to forcefully pack the molding sand into the mold, and there is a risk that the molding sand may collapse during pouring.

In addition, in both of the above two methods, foundry sand must be made exclusively for molds by adding a binder such as clay and water to sand particles, and the cost increases due to the binder. Moreover, it is dangerous that foundry sand that is exposed to a high temperature atmosphere contains a large amount of water.

The present invention provides a casting method that enables stable work by adding a step of suctioning and eliminating the air between sand grains to the full mold method, thereby making it possible to strongly solidify the sand without damaging the formwork. The purpose is to

The present invention will be specifically described below based on embodiments shown in the drawings.

Figure 1 shows an example of a casting mold.
The top surface is open and the side walls are double-layered, inside and outside.

The inner wall α2 is formed of a net having a large number of minute ventilation holes αJ with a diameter smaller than a grain of sand, and the outer wall αD is connected to a suction hose (4) connected to a suction device (not shown). There is.

Sand is poured into the formwork (1) to a predetermined height as shown by the two-dot chain line, and then a model (
3).

When the model (3) comes into contact with high heat, such as foamed resin, the mold (1) is instantly filled with sand, exposing only the upper end surfaces of the runner section (31) and the riser section (■), and the model ( 3) Bury it in sand.

An air-impermeable resin sheet (2) is placed over the entire top surface of the formwork (1) to form a barrier layer (5) that blocks the top surface of the sand layer from the outside air.

Prior to pouring, the suction device is operated to suck air between the sand grains out of the formwork through the ventilation hole α step in the inner wall α■ of the formwork (1).

As a result, the sand instantly becomes more compact than it was compacted,
However, unlike when compacting, no external force is applied, so the model (1)
will not cause any damage.

While suction is maintained, a ceramic sprue (6) is placed opposite the runner (2), and the molten metal is poured into the sprue (6).

Due to the high heat of the molten metal, the resin seal at the sprue (5a), runner section (2), model (3), and riser section (2) are burned out and replaced by molten metal. do.

After that, the suction is stopped, the mold is removed after the hot water has cooled and solidified, and the cast product is obtained.

As described above, the present invention does not impair the advantages of the full mold method, which eliminates the need for dividing the mold or removing the model from the sand mold, and also allows the sand to be instantly tightened by suctioning the mold. This allows for stable work without the sand crumbling when the model is burnt out and poured.

In addition, there are many advantages such as there is no need to add binders such as clay to sand, which makes it cheaper, and there is no need to mix water, so there is no danger in working in high-temperature atmospheres. It has a certain effect.

It goes without saying that the present invention is not limited to the above configuration, and that various modifications can be made within the technical scope of the claims.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a mold, and FIG. 2 is a sectional view of a conventional mold.

Claims (1)

[Claims] ■ A runner section Cl1) and a feeder section □□□ formed of an instant combustion material are formed in a formwork (1) having a large number of minute ventilation holes a3 on the wall surface and open at the top surface. A model (3) having a
1) The air in the formwork is sucked out of the formwork through the ventilation hole +13 to harden the sand, and then the molten metal is poured from the runner and the high heat of the hot water forms the model including the runner (311 and riser part). (3) A casting method in which molten metal is filled in place of the model while removing it by combustion, and the molten metal is cooled and solidified. ■ The casting method according to claim 1, wherein the instant combustion material is a foamed resin. ■ The casting method according to claim 1 or 2, wherein the barrier layer (5) is a resin sheet (5a) placed on the upper surface of the mold (1).