JPH04294857A - Method and device for casting aluminum - Google Patents

Abstract

PURPOSE:To secure sufficient molten metal running and to cast a thin product in high accuracy by incorporating aluminum metal from an opening part in a mold, heating and melting, evacuating air in closed space formed with a vessel and the mold and casting. CONSTITUTION:The mold 2 having gas permeability and providing a material incorporating part 22 at upper part of the mold is fixed into the vessel 1 having heat resistance as possible to close so as to communicate with out side the vessel only at the opening part 23 at the upper part and close in the other part. The aluminum metal is charged from the opening part 23 in the mold and incorporating into the material incorporating part 22 and heated from outside of the vessel and melted, and also the air in the closed space formed with the vessel and the mold is evacuated, and the casting is executed. By this method, the molten metal running is secured and the thin casting is manufactured in high accuracy and as the material for runner is scarcely necessary, yield of the casting is improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing aluminum castings with complex shapes and thin walls, and to an apparatus used to carry out the method.

[0002] In the present invention, the term "aluminum" means
The meaning includes pure aluminum and its alloys that mainly consist of aluminum, such as an alloy called ``Silmin'', which is made by adding a few percent of Si to Al, and an alloy that has age hardening properties by adding a small amount of Cu. use

0003

[Prior Art] Aluminum has a low melting point (m.p. 660
℃), and many alloys based on it have similarly low melting points, so casting should be relatively easy, but it is difficult to obtain thin-walled and highly precise products. Casting of products with shapes to which die casting cannot be applied is
Molten aluminum is cast into a mold, but the flow of the molten metal is left to its own devices, and the molten metal solidifies before it reaches the narrow space of the mold. Even if a feeder is to be used, aluminum is disadvantageous due to its low specific gravity, and if an attempt is made to use an effective feeder, the casting yield will be severely reduced.

[0004] In order to prevent solidification, attempts have been made to heat the mold above its melting point, but good results have not always been obtained. This is because the surface tension of the molten metal prevents the molten metal from circulating around the corners of the mold.

[0005]

[Problems to be Solved by the Invention] An object of the present invention is to provide a casting method that can be applied to aluminum casting, particularly when casting thin-walled products, to ensure hot water circulation and to obtain cast products with high precision. Our goal is to provide the following. It is also within the object of the invention to provide suitable casting equipment for use in carrying out the method.

[0006]

[Problems to Solve the Problems] The aluminum casting method of the present invention involves placing a mold, which is air permeable and has a material accommodating portion in the upper part of the mold, in a heat-resistant and sealable container. It is fixed so that only the opening communicates with the outside of the container and the other parts are sealed. Aluminum metal is charged through the opening of the mold and stored in the material storage area, and it is heated and melted, and the container and mold are sealed. It consists of casting by vacuum suctioning the air in a closed space formed by

The aluminum casting apparatus of the present invention is shown in FIG.
As shown in Figure 2, a sealable container (1) made of a material that is heat resistant and has good thermal conductivity, and a mold (21) made of a breathable material.
), a mold (2) having a material storage part (22) at the top thereof;
The container (1) consists of a heater (3) arranged around the container (1) and a case (4) made of fireproof material including the whole.
and mold (2) are a combination of shapes in which only the opening (23) of the mold communicates with the outside of the container, and the other parts are sealed,
It is constructed by adding means (6) for vacuum suctioning the closed space (5) formed between the container and the mold.

As the mold (2), any one selected from lost wax molds, sand molds, shell molds, plaster molds, and breathable molds can be suitably used.

Appropriate materials for the sealable container (1) include graphite and steel, particularly stainless steel.

0010

[Operation] In FIG. 1, the aluminum metal (7) charged into the material container (22) is heated through the wall of the closed container (1) by energizing the heater (3) and melted. Molten aluminum melted by other means may be poured, but aluminum is easy to melt, and solid aluminum is easier to handle and more convenient to charge in a certain amount.

The molten aluminum produced by melting is
Enter the lower mold as shown in Figure 2. As the vacuum suction means (6) operates to reduce the pressure in the closed space (5), the air remaining in the corners of the mold is also sucked out through the mold material. The molten metal (8) is pushed by the atmospheric pressure applied through the openings and circulates around the mold as shown in FIG. In conventional casting without vacuum suction, as shown in FIG. 4, the surface tension of the molten metal (8) sometimes prevents the molten metal from sufficiently reaching the corners.

0012

[Example] A cold impeller for a turbocharger was cast from pure aluminum. The thickness of the wing tip is 0.
．． Although the product is as thin as 4mm, when the present invention is used, the number of defects due to hot water circulation problems is reduced from 25% to 0.00mm compared to conventional products.
This has improved to 5%. According to the present invention, there is no need for a riser and only a small amount of material is required for the runner.
Casting yield (product weight/molten metal weight) improved from 30% to 60%.

[0013]

According to the casting method of the present invention, sufficient hot water circulation can be ensured in aluminum casting, and thin-walled products can be manufactured with high precision. Casting yields are improved because less material is spent on runners. This, combined with the remarkable improvement in the yield of good products, makes the so-called consistent yield (casting yield x yield of good products) dramatically better than in the prior art.

The casting apparatus of the present invention can be constructed without requiring any special parts and provides the above-described effects.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view showing the configuration of a casting apparatus of the present invention, and also shows the first stage of the casting method of the present invention.

[Fig. 2] Fig. 1 showing the second stage of the casting method of the present invention.
The corresponding figure.

FIG. 3 is an explanatory diagram of the effects related to the casting method of the present invention.

FIG. 4 is a diagram corresponding to FIG. 3 regarding the prior art.

[Explanation of symbols]

1 Container 2 Mold 21 Mold 22 Material storage section 23
Opening 3 Heater 4 Case 5 Sealed space 6 Vacuum suction means 7 Aluminum 8 Molten metal

Claims (5)

[Claims] Claim 1: A mold is placed in a heat-resistant and airtight container, which is air permeable and has a material storage part at the top of the mold, and is connected to the outside of the container only through the opening at the top, while the other parts are sealed. Aluminum metal is charged through the opening of the mold, placed in the material storage section, heated and melted, and the air in the closed space formed by the container and mold is vacuum-sucked. A method of casting aluminum that consists of casting. 2. The casting method according to claim 1, wherein the aluminum metal to be cast is selected from pure aluminum and an alloy mainly composed of aluminum. [Claim 3] A sealable container (1) made of a material that is heat resistant and has good thermal conductivity, a mold made of a breathable material (
A mold (21) is provided with a material storage part (22) on the upper part of the mold (21).
), a heater (3) placed around the container (1), and a case (4) made of fireproof material enclosing the entire container (
1) and mold (2) are a combination of shapes in which only the opening (22) of the mold communicates with the outside of the container and the other parts are sealed, and the closed space (5) formed between the container and the mold is ) An aluminum casting apparatus configured by adding means (6) for vacuum suction. 4. The casting apparatus according to claim 3, wherein the mold is selected from a lost wax mold, a sand mold, a shell mold, a plaster mold, and a permeable mold. 5. The casting apparatus according to claim 3, wherein the material of the sealable container is selected from graphite and steel.