JPH07116817A - Casting method and apparatus thereof - Google Patents

Abstract

PURPOSE:To reduce the dispersion of product quality, to improve the yield of production and to shorten the tact time by cooling a molten metal between a sprue and a stoke in the same pattern every time. CONSTITUTION:An upper metallic mold 1 and a lower metallic mold 2 are provided, and the sprue 3 is arranged in the lower metallic mold 2 so as to supply the pressurized molten metal from the lower part to the space formed between both the metallic molds. A hollow part 6 opened at the upper part is formed in the upper metallic mold 2 near the sprue, and plural nozzles 7 for blowing cooling air stream toward near the joining part of the sprue 3 and the space are arranged in the hollow part. By this constitution, supercooling of the sprue part can be prevented and also, feeder head effect is improved and the cooling of an ideal temp. gradient is executed, and the appearance of defective product caused by the development of blow hole, etc., can be reduced.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is used for low pressure casting of aluminum and other metals. The present invention is used in the manufacture of machine parts. The present invention has been implemented on a trial basis in the manufacture of a gear box that houses a transmission of an automobile, but can be widely applied to casting technology.

[0002]

2. Description of the Related Art A lower mold fixed to an apparatus and a detachable upper mold which is placed on the lower mold are provided with a molten metal pressurized in a space formed between the two molds. A method is widely used in which a casting product is manufactured by supplying the liquid, cooling it in a state where the space is filled with the molten metal, and when the molten metal solidifies, the upper die is removed. In the conventional low-pressure casting method, a gate is provided at the lowest position of the lower die, and the molten metal is supplied from the stalk (pipe) connected to the bottom of the lower die by pressure so as to resist gravity. It is taken. When cooling, the casting is directionally solidified and the pressure in the stalk is lowered when the casting finally solidifies, taking into consideration that the casting is solidified from the farthest place. And separate the molten metal in the stalk.

In such a method, if the vicinity of the sprue is solidified quickly, the molten metal communicating with the stalk can be quickly cut, which shortens the tact time for manufacturing one product, which is advantageous for mass production. Therefore, the molten metal passage near the gate is thinned so that the molten metal near the gate quickly solidifies. Further, conventionally, the pressure of the upper mold is made thin near the sprue, and a cooling airflow is supplied to the portion from the upper part of the upper mold to lower the temperature of the molten metal near the sprue.

[0004]

In the manufacturing process of such a cast product, if the molten metal between the sprue and the stalk is forcibly cooled and separated, the cast product is also affected and the product becomes a defective product. I will end up. Further, if the cooling is performed slowly, it takes time to remove the cast product, the tact time becomes long, and the manufacturing efficiency cannot be improved.

The present invention has been made against such a background, and the cooling nozzle is directed to the side surface to surely solidify the product portion faster than the sprue portion to produce a sound product and reduce defective products. It is an object of the present invention to provide an apparatus and a method for manufacturing a cast product, which is capable of reducing the takt time.

[0006]

According to the present invention, a cavity having an upper opening is formed in an upper mold near a sprue, and a cooling airflow is provided in the cavity toward a vicinity of a joint between the sprue and a casting. After arranging a plurality of nozzles for spraying, the space between the upper mold and the lower mold is filled with the molten metal, and then the cooling airflow from the plurality of nozzles (for example, an airflow in which water is atomized into the air) ) Is sprayed on the side surface near the sprue.

[0007]

When the molten metal in the joint portion is locally solidified, the pressure of the stalk is lowered and the molten metal in the stalk is dropped, so that the cast product and the molten metal in the stalk can be cut at the joint portion. This is done before the molten metal of the casting has been sufficiently solidified. As a result, the cut surface of the joint becomes the same shape every time, the number of defective products is reduced, and the tact time of manufacturing can be shortened.

[0008]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is an enlarged sectional view of a sprue part according to an embodiment of the present invention,
2 is a sectional view showing the structure of the casting apparatus according to the embodiment of the present invention, FIG. 3 is a sectional view of a cast product cast by the casting apparatus of the present invention, and FIG. 4 is a casting apparatus of the present invention. It is a perspective view showing the appearance shape of the cast product.

As shown in FIG. 1, an essential part of the embodiment of the present invention comprises an upper mold 1 and a lower mold 2, and a space formed between the two molds is pressed from below. The lower die 2 is provided with a sprue 3 for supplying the molten metal, and a cavity 6 opening upward is formed in the upper die 1 near the spout 3 and the spout 3 and the space are formed in the cavity 6. A plurality of nozzles 7 for spraying the cooling airflow toward the vicinity of the joint portion are provided.

As shown in FIG. 2, the lower mold 2 has a molten metal 11
The stalk 4 for supplying the molten metal 11 is fixed to the gate 3 on the fixed plate 13 on the heating and holding furnace 12 in which the molten metal 11 is accumulated. The heating and holding furnace 12 has an injection port 14 for injecting the molten metal 11 and a lid 15 covering the injection port 14.
A heater 16 for heating the molten metal 11 and an air pressure supply port 17 for supplying compressed air for pushing the molten metal 11 into the stalk 4.

The upper mold 1 is inserted into at least four guide columns 18 and fixed to a movable plate 20 which slides up and down by one or more mold pressurizing hydraulic cylinders 19. Is provided with an air supply pipe 8 connected to the nozzle 7, a water supply pipe 9 for supplying cooling water, and a discharge pipe 10 for discharging steam generated by the supplied air and water. The air supply pipe 8 and the water supply pipe 9 join outside the upper mold 1 to form an air flow and are connected to the nozzle 7.

In the casting apparatus according to the embodiment of the present invention thus constructed, the upper die 1 is placed on the lower die 2 and pressurized (die clamped) by the die press hydraulic cylinder 19. When the compressed air from the air pressure supply port 17 is supplied to the molten metal 11 in the heating and holding furnace 12, the molten metal 11 rises in the stalk 4 so as to resist gravity and is supplied into the mold space via the gate 3. It When the mold space is filled with the melt 11, the mixture of the air and the cooling water is supplied into the cavity 6 and is sprayed from the plurality of nozzles 7 to the part of the melt 11 on the mold space side slightly away from the gate 3. It

When the molten metal 11 in the vicinity of the sprue 3 begins to solidify due to the injection of the mixture of air and cooling water, if the supply of compressed air from the air pressure supply port 17 into the heating and holding furnace 12 is stopped, the tossock is produced. The molten metal 11 pushed up inside was returned to the heating and holding furnace, and the cast product 21 and the stalk 4
The inner molten metal 11 is cut. The air and cooling water supplied into the cavity 6 become steam and are discharged from the discharge pipe 10.

The feature of the present invention is that the cooling by the air and the cooling water is not performed directly on the sprue 3 side but toward the inner circumference of the cavity 6 at a position slightly distant from the sprue 3. Therefore, the molten metal 11 between the sprue 3 and the stalk 4 is prevented from being rapidly cooled, and cavities or cracks caused by a temperature difference are prevented.

As described above, when the molten metal 11 is filled in the mold space and the supply thereof is stopped to cool the vicinity of the gate, air and cooling water are not directly jetted toward the gate 3 but the gate 3 side. By injecting from the plurality of nozzles 7 into the inner periphery of the cavity 6 slightly away from the cavity 6, it is possible to prevent a portion of the sprue 3 from being rapidly cooled and causing a large temperature difference with the molten metal 11 in the mold space. be able to.

When the molten metal 11 filling the mold space is solidified, the mold pressurizing hydraulic cylinder 19 is operated to move the movable plate 20 upward along the guide column 18, whereby the upper mold 1 is moved to the lower mold. The cast product 21 as shown in FIGS. 3 and 4, which is separated from the mold 2 and formed by solidifying the molten metal 11 from the lower mold 2, is taken out.

[0017]

As described above, according to the present invention, it is possible to prevent overcooling of the sprue portion, improve the feeder effect, and perform cooling with an ideal temperature gradient. As a result, cooling can be performed in the same pattern every time, and it is possible to reduce the generation of defective products due to generation of cavities or cracks, and it is possible to improve the manufacturing yield and shorten the tact time.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of a sprue part according to an embodiment of the present invention.

FIG. 2 is a sectional view showing the configuration of a casting apparatus according to an embodiment of the present invention.

FIG. 3 is a view showing a cross section of a cast product cast by the casting apparatus according to the embodiment of the present invention.

FIG. 4 is a perspective view showing an external shape of a cast product cast by the casting apparatus according to the embodiment of the present invention.

[Explanation of symbols]

 1 Upper mold 2 Lower mold 3 Gate 4 Stoke 6 Cavity 7 Nozzle 8 Air supply pipe 9 Water supply pipe 10 Discharge pipe 11 Molten metal 12 Heating and holding furnace 13 Fixing plate 14 Injection port 15 Lid 16 Heater 17 Air pressure supply port 18 Guide column 19 Hydraulic cylinder for pressurizing mold 20 Movable plate 21 Cast product 22 Hot water

Claims (2)

[Claims] 1. An upper mold and a lower mold are provided, and a gate is provided in the lower mold so as to supply a molten metal pressurized from below to a space formed between the upper mold and the lower mold. In the casting apparatus, a cavity that opens upward is formed in the upper mold near the sprue, and a plurality of nozzles that blow a cooling airflow toward the vicinity of the joint between the sprue and the space are provided in the cavity. Casting device characterized by the above. 2. A molten metal is pressurized and supplied from a gate provided in the lower mold into a space formed between the upper mold and the lower mold, and when the space is filled with the molten metal, A casting method characterized in that a cooling airflow is blown from a plurality of nozzles from a cavity provided in an upper mold near the gate toward the vicinity of a joint between the gate and the space.