JP2870360B2 - Casting method of large structure made of aluminum alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of casting a large structure made of aluminum alloy such as a hull of a small boat such as a motor boat or a cruiser, a vehicle body or a concrete formwork.

[0002]

2. Description of the Related Art In recent years, aluminum or aluminum alloys have features such as light weight, strong rust prevention, and easy recycling after disposal. However, aluminum or aluminum alloy has the above-mentioned characteristics, but has a low melting point and is easy to solidify, so that it has poor castability. For this reason, although it is practically used as a small part such as a cylinder head or an aluminum wheel as a part integrally formed as a casting, most large structures are still structures obtained by welding plate materials.

[0003]

Although some attempts have been made to cast large aluminum alloy structures using a sand mold, the casting method using a conventional sand mold has a rough casting surface. In addition, many casting defects such as cavities occur and it is far from practical use.

The present invention relates to a large and thin cast product having a length of about 5 to 9 m and a thickness of about 3 to 6 mm, such as the hull of a small boat such as a motor boat or a cruiser.
An object of the present invention is to provide a method of casting a large cast product made of an aluminum alloy, which can be cast to a uniform thickness and does not cause casting defects such as nests.

[0005]

According to the present invention, a mold having a cavity surface coated with a mold is provided with an inclination angle θ of 5 to 35.
And the molten metal temperature of the aluminum alloy during casting is desirably 30 to 1 lower than the liquidus temperature of the aluminum alloy.
By increasing the mold temperature by 20 ° C. and lowering the mold temperature by 100 to 270 ° C. than the solid phase temperature of the aluminum alloy, and pouring the molten aluminum alloy from the lower end of the mold through low pressure casting through stalk, for example, a motor boat, cruiser Thus, a method for casting a large structure made of an aluminum alloy, such as a hull of a small ship, can be obtained.

Further, according to the present invention, a mold having a cavity surface coated with a mold is maintained at an inclination angle θ of 5 to 35 degrees, and the mold is covered with a decompression container to form a cavity in the mold. , The temperature of the molten aluminum alloy during casting is preferably set to 30 degrees below the liquidus temperature of the aluminum alloy.
To 120 ° C. higher, the mold temperature is 100 to 270 ° C. lower than the solid phase temperature of the aluminum alloy, and the aluminum alloy melt is injected from the lower end of the mold through a stalk by a low-pressure casting method. A method for casting a large structure made of an aluminum alloy, such as a hull of a small ship such as a cruiser, is obtained.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a first embodiment of an apparatus for carrying out the method of the present invention will be described with reference to FIG.

FIG. 1 shows an outline of a casting apparatus for carrying out the present invention. In FIG. 1, reference numeral 1 denotes a mold, which is composed of an outer mold 1a and an inner mold 1b, and has a shape corresponding to the shape of a molded product. A cavity 2 is formed. It is needless to say that the mold 1 is a normal split mold, and may be constituted by three or more split dies according to the shape of the molded product.

The cavity surface of the mold 1 has a thickness of 0.1 mm.
A coating mold of about 1 to 0.5 mm is applied by spraying or brushing. This coating mold is made of alumina, magnesia, titanium oxide having a particle size of 200 mesh or less in a mixed solution of water glass and water, in consideration of the running property of the casting, the heat insulation property and the smoothness of the casting surface of the casting. Alternatively, a material obtained by appropriately mixing graphite or the like is used.

The mold 1 has a tilt angle θ in a cast state.
Is held at an angle of 5 to 35 degrees and inclined upward. This is because, while improving the meltability during casting, preventing turbulence and shunting of the molten metal, if the inclination angle θ is too large, a high casting pressure is required, and the meltability is worsened. .

Therefore, for example, when the molded product is curved in a dish shape as shown in FIG. 4, it is necessary to hold the cavity so as to have a downwardly inclined shape as shown in FIG. In the example shown in FIG. 4, if the shape is received as shown in FIG. 4b, a part of the cavity faces downward, and in this part, the molten metal falls naturally and causes turbulence and branch flow. It is desirable to avoid such an arrangement, but if it cannot be avoided, the inclination angle θ of the entire mold 1 is adjusted.

Reference numeral 3 denotes a hot water supply device of a low-pressure casting device, and a ladle 5 filled with an aluminum alloy melt 4 to be cast, and a ladle 5
And an airtight pressurized container 6 containing
A gas supply control device 7 for supplying a pressurized gas such as argon or nitrogen.

Reference numeral 8 denotes a stalk, one end of which is connected to a gate 9 provided at the lower end of the mold 1, and the other end of which is inside the aluminum alloy melt 4 filled in the ladle 5 through the pressure vessel 6. Is immersed in.

Next, a method for casting a large structure made of an aluminum alloy according to the present invention will be described with reference to FIG. Prior to casting, the temperature of the molten aluminum alloy 4 to be cast is 30 to 120 ° C. higher than the liquidus temperature of the aluminum alloy, and the mold temperature is 100 to 2 degrees higher than the solidus temperature of the aluminum alloy.
Adjust so as to lower by 70 ° C. The reason why the temperature of the molten metal 4 of the aluminum alloy and the temperature of the mold are varied is to select the temperature according to the size and shape of the product to be cast.

After making these settings, as shown in FIG.
The gas supply control device 7 is operated to supply a pressurized gas such as air, argon or nitrogen to the pressurized container 6, and when the inside of the pressurized container 6 is pressurized, the ladle 5 is filled with the pressurized gas. The molten aluminum alloy 4 is pressurized and supplied to the cavity 2 through a gate 9 provided at the lower end of the mold 1 via a stalk 8.

At this time, when the inside of the pressurized container 6 is rapidly pressurized, the pressurized gas enters the molten aluminum alloy 4 filled in the ladle 5 and is caught in the stalk 8 to form a cavity together with the molten aluminum alloy 4. In order to prevent the pressurized gas from being entrained, 0.015 to 0.01 m is required from the start of casting until the molten aluminum alloy 4 reaches the gate 9 of the mold 1. To 0.35
The molten metal 4 is pushed up at a low speed by pressurizing at a low pressure of 0 kgf / cm ^{2. After} the molten metal 4 reaches the gate 9 of the mold 1, the molten metal 4 is high-speed at a high pressure of 0.7 to 3.0 kgf / cm ^2. Inject with.

Next, the second embodiment of the apparatus for implementing the method of the present invention will be described.
An embodiment will be described with reference to FIGS. Since this embodiment is also basically the same as the first embodiment, the same components are denoted by the same reference numerals, description thereof will be simplified, and differences will be mainly described.

FIGS. 2 and 3 show an outline of a casting apparatus for carrying out the present invention. In the figures, reference numeral 1 denotes a mold, which is constituted by an outer mold 1a and an inner mold 1b, and has a shape of a molded product therein. Is formed.

A mold having a thickness of about 0.1 to 0.5 mm is applied to the cavity surface of the mold 1 by spraying or brushing, as in the above embodiment. In the casting state, the mold 1 is held inclined upward with an inclination angle θ of 5 to 35 degrees.

The above construction is the same as that of the first embodiment described above.
The two bricks 10a and 10b are overlapped, and one of them can be slid by, for example, a hydraulic cylinder 11, and the holes 12a and 12b formed in the two bricks 10a and 10b are aligned or shifted. A slide gate 13 for opening and closing the nozzle is provided.

The mold 1 including the slide gate 13 is housed in an airtight vacuum container 14, which is connected to a vacuum pump 15. In the example of FIG. 2, the mold 1 is entirely housed in the decompression container 14. However, when sufficient decompression force is obtained in consideration of the airtightness and decompression force of the mold 1, A hole in the upper end (the part farthest from the gate 9) of the
May be connected.

In the case of the second embodiment, similarly to the first embodiment, for example, when the molded product is curved in a dish shape as shown in FIG. 4, it is turned down as shown in FIG. 4a. It is desirable to hold the cavity so that the cavity has an upward slope as a whole. If the cavity shown in FIG. 4B is used as shown in FIG. 4B, the cavity 2 partially faces downward. It is desirable to avoid such an arrangement because the molten metal naturally falls and causes turbulence and branch flow. However, since the inside of the cavity 2 can be depressurized, the runnability in the cavity 2 is improved by that amount. The inclination angle θ of the mold 1 can be reduced as compared with the embodiment.

Reference numeral 3 denotes a hot water supply device for a low-pressure casting device similar to that of the first embodiment, but as described above, in this embodiment, a slide gate 13 is provided at the lower end 9 of the mold 1 at the gate 9.
Is provided, a stoke 8 connecting the hot water supply device 3 (aluminum alloy molten metal 4) of the low pressure casting device and the mold 1 is provided.
Is connected to the lower end of the slide gate 13, and is connected to the mold 1 (gate 9) via the slide gate 13.

Next, the method for casting a large-sized aluminum alloy structure of the present invention will be described with reference to FIGS. As in the first embodiment, prior to casting, the temperature of the molten aluminum alloy 4 to be cast is 30 to 120 ° C. higher than the liquidus temperature of the aluminum alloy, and the mold temperature is 100 to 120 ° C. higher than the solidus temperature of the aluminum alloy. Adjust so as to lower by 270 ° C.

After making these settings, the slide gate 13
Is closed, the gas supply control device 7 and the vacuum pump 15 are operated, and a pressurized gas such as air, argon or nitrogen is supplied to the pressurized container 6, and the inside of the pressurized container 6 is pressurized. The pressure inside the pressure reducing container 14 (the cavity 2 of the mold 1) is reduced.

Then, the pressure vessel 6 has a pressure of 0.1 to 3.0 k.
gf / cm ² , and the decompression container 14 is set to 760 Torr.
When the pressure is reduced to a constant pressure state, the slide gate 13 is opened. As a result, the pressurized aluminum alloy melt 4 in the pressurized container 7 enters the cavity 2 in the depressurized mold 1 through the stalk 8. Injected.

In contrast to the first embodiment in which the molten aluminum alloy 4 pressurized in the pressure vessel 6 is simply injected, in the case of this embodiment, the gold into which the molten aluminum alloy 4 is injected is provided. Since the cavity 2 in the mold 1 is also decompressed, the aluminum alloy melt 4 hardly comes into contact with air during injection into the mold 1, which can prevent micro-porosity from occurring, and can produce a higher quality cast product. In addition to being obtainable, casting of larger castings, which is difficult only by pressure casting, is possible.

[0028]

As described above, according to the present invention, an aluminum alloy having a low melting point and easy solidification and poor castability is cast in a thermodynamically and hydrodynamically balanced manner. Even large-sized, thin-walled structures such as the hulls of small ships such as cruisers can be cast to a uniform thickness. In addition, it is possible to obtain a large cast product made of an aluminum alloy having a clean casting surface without casting defects such as nests. And the like.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a casting apparatus for performing a method of the present invention.

FIG. 2 is a schematic sectional view showing another example of a casting apparatus for performing the method of the present invention.

FIG. 3 is an exploded perspective view of the slide gate shown in FIG.

FIG. 4 is a schematic side view showing an example of a mold arrangement when implementing the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 mold 2 cavity 3 low-pressure casting apparatus hot water supply device 4 molten aluminum alloy 5 ladle 6 pressurized container 7 gas supply control device 8 stalk 9 sluice 13 slide gate 14 depressurized container 15 vacuum pump

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B22D 21/04 B22D 21/04 A 25/02 25/02 D 27/04 27/04 Z 27/18 27/18 B B63B 3 / 09 B63B 3/09 (58) Fields investigated (Int.Cl. ⁶ , DB name) B22D 18/04 B22D 18/06 509 B22D 18/08 501 B22D 21/04 B22D 25/02 B22D 27/04 B22D 27 / 18

Claims (4)

(57) [Claims] 1. A mold having a cavity surface coated with a mold,
A method for casting a large structure made of aluminum alloy, characterized by injecting an aluminum alloy melt from a lower end of the mold through a stalk by a low pressure casting method while maintaining the inclination angle θ at 5 to 35 degrees. 2. A mold having a cavity surface coated with a mold,
While maintaining the inclination angle θ at 5 to 35 degrees, the mold is covered with a decompression container, and while the cavity in the mold is depressurized, the molten aluminum alloy is injected from the lower end of the mold through a stalk by low pressure casting. A method for casting a large structure made of an aluminum alloy, characterized by comprising: 3. The temperature of the molten aluminum alloy during casting is 30 to 120 ° C. lower than the liquidus temperature of the aluminum alloy.
Higher mold temperature than solid state temperature of aluminum alloy
The temperature is lower by 00 to 270 ° C.
A method for casting a large-sized structure made of an aluminum alloy according to the above. 4. The method for casting a large aluminum alloy structure according to claim 1, wherein the aluminum alloy large structure is a hull of a small boat such as a motor boat or a cruiser. .