JPH04294858A - 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 covering a cover on a mold, charging aluminum alloy into an opening part in a core, heating and melting, evacuating air in closed space formed between the cover and the core and casting. CONSTITUTION:The mold 1 is formed by assembling the core 12 having permeability and providing the opening part 13 to a master mold 11 having heat resistance and non-permeability. The cover 2 is covered on this mold so as to close part communicated with the out part only at the opening part in the core, and by using the heat resistant seal, gap between the cover and the core is sealed. The aluminum metal is charged into the opening part in the core and heated from outside of the mold and melted and also, the air in the closed space 5 formed between the cover and the core is evacuated and the casting is executed. By this method, the thin product is manufactured at high accuracy, and also 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 be Solved] The method of casting aluminum of the present invention involves forming a mold by combining a heat-resistant, non-porous main mold with a ventilated core having openings. , this mold is covered with a lid so that only the opening of the core communicates with the outside and the other parts are sealed, aluminum metal is charged into the opening of the core, and this is heated and melted. , consisting of casting by vacuum suctioning the air in the closed space formed between the lid and the core.

The aluminum casting apparatus of the present invention is shown in FIG.
As shown in the figure, there is a main mold (11) made of a material that is heat-resistant, non-porous, and has good thermal conductivity, and a core (12) made of a material that is breathable and has an opening (13). A mold (1) consisting of a lid (2) that is combined with the main mold, a heat-resistant seal (5) that seals between the lid and the core, and a heater (3) placed around the mold (1). ) and a case (4) made of refractory material enclosing the whole, the mold (1) has a seal (5)
The mold has a shape in which only the opening (22) of the mold communicates with the outside and the other parts are sealed, and a means (6) for vacuuming the sealed space (5) formed between the lid and the mold is added. It is composed of

Appropriate materials for the main mold (11) are graphite and steel, particularly stainless steel.

As the core (12), any one selected from lost wax molds, sand molds, shell molds, plaster molds, and vent molds can be suitably used.

0010

In FIG. 1, the aluminum metal (7) charged into the opening (13) is heated through the wall of the main mold (11) 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, the mold is poured into a mold with the shape shown in Figure 3, and vacuum suction is not performed, so as shown in Figure 4, the surface tension of the molten metal (8) prevents the molten metal (8) from filling sufficiently to the corners. There were times when it wouldn't turn.

0012

[Example] A windmill was cast from pure aluminum. Although the product has a thin blade tip with a thickness of 0.6 mm, when the present invention was used, the number of defects due to hot water circulation problems was reduced from 35% of the conventional product to 1%. According to the present invention, there is no need for a riser and only a small amount of material is required for the runner, so the casting yield (product weight/molten metal weight) can be reduced.
This has improved from the previous 20% 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.

FIG. 5 is a vertical cross-sectional view of a mold, explaining a conventional casting method.

[Explanation of symbols]

1 Mold 11 Main mold 12 Core 13 Opening 2 Lid 3 Heater 4 Case 5 Sealed space 6 Vacuum suction means 7 Aluminum 8 Molten metal

Claims (5)

[Claims] [Claim 1] A mold is formed by combining a heat-resistant, non-air permeable main mold with a core that is air permeable and has an opening, and this mold is connected to the outside through only the opening of the core. Cover the lid so that it communicates with the other parts and seal it, then charge the aluminum metal into the opening of the core, heat it and melt it, and create a sealed space between the lid and the core. A method of casting aluminum that consists of casting by vacuum suction of air inside. 2. The method of casting aluminum according to claim 1, wherein the aluminum metal to be cast is selected from pure aluminum and an aluminum-based alloy. [Claim 3] A main mold (11) made of a material that is heat-resistant, non-porous, and has good thermal conductivity, and a core (12) made of a breathable material and having an opening (13). A mold (1) consisting of a lid (2) that is combined with the main mold, a heat-resistant seal (5) that seals between the lid and the core, and a heater (3) placed around the mold (1). ) and a case (4) made of refractory material enclosing the whole, the mold (1) has a seal (5
), the mold has a shape in which only the opening (22) of the mold communicates with the outside and the other parts are sealed, and a means (6) for vacuuming the sealed space (5) formed between the lid and the mold is provided. In addition, equipment for casting aluminum composed. 4. The apparatus for casting aluminum 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. Apparatus for casting aluminum according to claim 3, wherein the material of the sealable container is selected from graphite and steel.