JPH0647148B2 - Mold - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a mold, and particularly to precision molding using a low melting point alloy such as aluminum, zinc, or copper based on a gypsum mold. The present invention relates to a mold formed by casting.

(Prior Art) Conventionally, dies used for die casting, synthetic resin molding, etc. have been formed by machining tool steel.
This required many production days and costs.

For this reason, the use of molds for trial production or small-quantity production causes a prolongation of the trial production period and soaring trial costs, and in small-scale production, an increase in product cost due to an increase in the amortization burden of die costs. The result was.

It is possible to use a simple mold manufactured by various methods in order to eliminate the above-mentioned harmful effects, and one of them is a mold made by casting using a low melting point alloy such as aluminum, zinc, or copper. is there.

In particular, among the molds formed by casting, a mold by a precision casting method using a gypsum mold is excellent in transferability of the mold surface and is a simple mold excellent in that the manufacturing period is short.

The manufacturing method of this mold is as shown in FIGS. 4 and 5. First, as shown in FIG. 4, the master 2 is placed and fixed on the surface plate 1 and then surrounded by the mold 3, and the mold 3 A silicone rubber for molding is poured into the inside and cured to form a silicone rubber mold.

Next, a gypsum mold 5 contained in a mold 6 as shown in FIG. 5 is formed on the basis of the silicone rubber mold, and the gypsum mold is used to form an aluminum-based, zinc-based, copper-based alloy in the mold 7. After the molten metal is poured, it is cooled and solidified to form a mold 8.

(Problems to be solved by the invention) A casting mold using a gypsum mold has casting defects such as "sink" and "nest" on the surface due to the low thermal conductivity of gypsum, Alternatively, it has a defect that the surface roughness becomes poor due to the coarse grain size.

For example, when the aluminum alloy AC4C is cast at 615 to 625 ° C., the cooling rate at the mold interface of the molten metal is S
The mold using KD6 has a temperature of 50 ° C / sec, while the gypsum mold has an extremely slow rate of 0.16 ° C / sec.

As a result, as shown in FIG. 5, in the vicinity of the convex thick portion 5a of the gypsum mold 5, the heat of the lid when the molten metal was flowing was added to delay the solidification of the molten metal, and so-called partial nonuniform cooling rate of the molten metal occurred. It becomes a heat spot and casting defects are likely to occur.

When a mold with a slow cooling rate is used in this way, a casting defect occurs due to the generation of heat spots due to the partial non-uniformity of the cooling rate of the molten metal based on the shape of the mold, so to prevent this, the surface of the molten metal is heated with a gas burner. Measures have been taken to cover or cover with heat insulating material.

This method requires skill in heating with a gas burner, and the solidification rate of the molten metal becomes slow, so the grain size of the cast product becomes coarse, the surface roughness deteriorates, and many man-hours are required for surface finishing. Had.

The present invention has been made as a result of intensive studies in order to form a mold having a smooth surface and no casting defects in view of the above-mentioned current situation.

(Means for Solving the Problems) That is, the present invention is based on a gypsum mold in which a cooling pipe is embedded, while cooling and vacuum exhausting the gypsum mold, a low-melting alloy such as an aluminum-based, zinc-based, or copper-based alloy. It is a mold characterized by being formed by casting.

(Function) The present invention is configured as described above, and its function is to cool the mold by the cooling pipe embedded in the gypsum mold to improve the cooling rate of the molten metal and to make the surface uniform by performing vacuum exhaust. The goal is to form a mold that is smooth and free of casting defects.

(Embodiment) An embodiment of the present invention will be described with reference to FIGS. 1 to 3. First, as shown in FIG. 1, a mold shape for forming a bendable cooling pipe 10 in a mold 9 is formed. In consideration of this, the sheet is bent appropriately, and both ends thereof are held in the holes 11 provided in the side plate as appropriate.

Next, as shown in FIG. 2, as shown in FIG. 4, the mold 9 having the cooling pipe 10 is mounted on the rubber mold 12 formed on the basis of the master. The cooling pipe 10 is the cavity 12a of the rubber mold 12. The gypsum slurry 13 is poured into the mold 9 and hardened to form a gypsum mold in which a cooling pipe is embedded.

Then, as shown in FIG. 3, an exhaust plate 15 having an exhaust groove 17 for connecting a gypsum mold 14 formed by embedding the cooling pipe 10 based on the rubber mold 12 to the exhaust hole 16 as described above is formed on the surface. After placing on top, the form 18 is placed and printed on the plaster mold 14.

After setting the mold as described above, the exhaust hole 1 of the exhaust plate 15
The gypsum mold 14 is evacuated from 6 and the cooling pipe 1
A molten metal 19 of a low melting point alloy such as aluminum, zinc, or copper is poured into the mold 18 while a refrigerant such as ice is circulated at 0, and is cooled and solidified to form a mold.

When the forming method as described above is adopted, the gypsum mold 14 has a low air permeability, so that the molten metal 19 is well adsorbed on the surface by vacuum evacuation and the shape thereof is precisely transferred and the cooling pipe 10
Due to the improvement and uniformization of the cooling rate by the flow of the refrigerant into the casting mold, a dense casting mold having a low surface roughness and having no casting defects such as "sinking" and "cavities" can be formed.

When burying the cooling pipe 10 in the gypsum mold 14, the cooling pipe 10 is appropriately folded in consideration of preventing the generation of a heat spot on the cast product due to the uneven cooling rate due to the mold shape as described above. It goes without saying that it is necessary to bend or set this number.

(Effect) The present invention has the above-mentioned constitution and operation, and its effect is to make a trial or a trial by using a mold having a smooth surface and a casting defect which is obtained by precision casting by an extremely simple method. It is to streamline small-scale production work and reduce costs.

[Brief description of drawings]

1 to 3 show a mold forming method of the present invention, and FIG.
FIG. 5 and FIG. 5 are views showing a conventional mold forming method. 10 ... Cooling pipe, 14 ... Gypsum mold, 15 ... Exhaust plate, 18 ... Formwork, 19 ... Low melting point alloy melt.

Claims (1)

[Claims] 1. An aluminum system based on a gypsum mold in which a cooling pipe is embedded while cooling the gypsum mold and evacuation.
A mold characterized by being formed by casting a low melting point alloy such as zinc-based or copper-based.