JPH0649416Y2 - Suction casting equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a suction casting apparatus, and more particularly to a suction casting apparatus that prevents air leaked during suction casting from entering a mold cavity.

(Prior art) Compared with general gravity casting method, the suction casting method reduces the pressure inside the mold cavity, so that the melt flow is good, and since the molten metal is gently introduced from below, there is less gas entrapment in the mold cavity. Have advantages. Further, since all of the molten metal heat retaining furnace or the molten metal in the melting furnace acts as a molten metal, there is an advantage that the molten metal has a great effect.

A conventional suction casting device will be described with reference to FIG. This suction casting apparatus 2 is covered by a mold 5 composed of an upper mold 3 and a lower mold 4 made of sand, a surface plate 10 on which the mold 5 is placed, and the surface plate 10 in a hermetically sealed state. A chamber 8 having a reduced pressure exhaust port 9 and a stalk 12 with a flange which is communicated with a spout 7 provided below the lower mold 4 and is inserted into a support hole 11 of the platen 10 are provided. Also,
A sealing material 13 for preventing pressure leakage is provided between the chamber 8 and the surface plate 10 and between the surface plate 10 and the flange of the stalk 12.
Sandwiched between. When casting with this device 2,
When the lower part of the stalk 12 is immersed in the molten metal 15 in the heat insulation furnace 14 while decompressing the inside of the chamber 8 by a vacuum pump (not shown) connected to the decompression exhaust port 9, the molten metal 15 will pass through the stalk 12 to form the cavity 6 It is sucked up inside and filled. Next, after the molten metal 15 in the cavity 6 has solidified, the mold 5 is taken out and the mold is disassembled to take out the casting.

(Problems to be solved by the invention) As described above, the suction casting apparatus uses the pressure difference between the pressure generated by depressurizing the mold and the atmospheric pressure applied to the molten metal in the heat-retaining furnace to create a mold inside the mold. Suck up the molten metal. During this suction casting, since the pressure inside the mold is always negative, if a small amount of air leaks from each seal part (between the chamber and the surface plate and between the surface plate and the stalk), this leaked air is sucked up. It is caught in the molten metal in the formed cavity and remains as a gas defect in the casting, which causes a problem of lowering the product yield. The present invention is intended to solve such a problem, and its purpose is to prevent air leaking from each seal part from flowing into the cavity to prevent gas defects in the casting. The object is to provide a device for obtaining a sound casting.

(Means for Solving the Problems) The suction casting apparatus of the present invention comprises a surface plate, a chamber placed on the surface plate, a mold in the chamber, and a molten metal sent to the mold from its lower surface. It is composed of a stalk penetrating the surface plate, the surface plate has a box structure, a decompression exhaust port and a vent hole provided on the upper surface, the mold is installed above the surface plate upper surface and the surface plate upper surface and the mold lower surface. A space is formed between the chamber and the surface plate, and the air that has flowed into the chamber from between the surface plate and the stalk, without passing through the cavity of the mold, It is characterized in that a decompression means for exhausting from the decompression exhaust port through the ventilation hole and decompressing the inside of the cavity is connected to the decompression exhaust port.

In the device of the present invention, a decompression means such as a vacuum pump is connected to the decompression exhaust port to decompress, and the air in the chamber, mold and cavity is exhausted from the ventilation holes provided in the surface plate, and the cavity The inside becomes negative pressure, and the molten metal can be filled in the cavity by immersing the stalk in this state in the molten metal in the heat insulation furnace (or the melting furnace or the like).

The suction casting apparatus of the present invention is an apparatus for sucking molten metal to fill the mold cavity for casting, and is not particularly limited as long as it has the above structure.

Any mold may be used as long as it is breathable, and a sand mold is particularly preferable.

The ventilation holes on the surface plate are designed to efficiently exhaust the air inside the mold.
It is preferable to provide a large number of pieces uniformly on the mold side. Further, the reduced pressure exhaust port of the surface plate is provided on a side different from the side where the vent hole is provided. As a result, the mold and the reduced pressure exhaust port are spatially connected to each other through the ventilation hole, and the air in the mold can be guided to the reduced pressure exhaust port.

Further, it is preferable to sandwich a sealing material for preventing pressure leakage between the parts of the device of the present invention that are in contact with each other, that is, between the chamber and the surface plate, the surface plate and the stalk and the like.

(Operation) The suction casting device of the present invention has a box-like platen that forms a space for containing the mold with the chamber placed on it, and has a decompression exhaust port and a vent hole on the upper surface, and the lower surface of the mold. By forming the space between the upper surface of the surface plate and the air leaked from the seal portion between the chamber and the surface plate and the sealing portion between the surface plate and the stalk, the air leaked from the space between the lower surface of the mold and the upper surface of the surface plate. Since it enters the surface plate through the ventilation holes on the surface plate and flows to the decompression exhaust port, it does not pass through the mold cavity and therefore does not leave a gas defect in the casting.

(Embodiment) The present invention will be described with reference to the drawings according to an embodiment.

As shown in FIG. 1, the suction casting apparatus 1 of the present invention comprises a surface plate 10 having a box structure and a chamber 8 mounted on the surface plate 10.
And a mold 5 that is housed in the chamber 8 and is composed of an upper mold 3 and a lower mold 4 made of sand, and a sprue 7 provided in the lower mold 4 of the mold 5 to communicate with each other to support a surface plate 10. It is generally composed of a flanged stalk 12 inserted in a hole 11.

In addition, the surface plate 10 having a box structure has a decompression exhaust port 9 on the side surface.
And a large number of vent holes 16 are evenly provided on the upper surface of the mold 5. A part of the lower surface of the mold 5 is supported by the surface plate 10 through the stalk 12, and the lower surface of the mold 5 and the upper surface of the surface plate 10 are A space is formed between them.

Furthermore, between the chamber 8 and the surface plate 10 and between the surface plate 10 and the stalk
A seal material 13 for preventing pressure leakage is sandwiched between the 12 flanges.

Fe-based small parts (lactide cast iron) are cast by this apparatus 1. The inside of the chamber 8 is depressurized to a predetermined degree of vacuum by a vacuum pump (not shown) connected to the depressurization exhaust port 9 of the surface plate 10. Next, when the lower part of the stalk 12 is immersed in the molten metal 15 in the heat insulation furnace 14 installed below the apparatus 1, the molten metal 15 is sucked up into the cavity 6 through the stalk 12 and filled. Next, after the molten metal 15 in the cavity 6 has solidified,
The casting is taken out by taking out the mold 5 and removing the mold.

The gas defect occurrence rate of the casting (Fe-based small component) manufactured in this manner was examined. For comparison, the same test was conducted using the conventional apparatus shown in FIG. As a result, the gas defect generation rate of castings (generation rate for 1000 products) by the conventional apparatus was 30%, whereas that by the apparatus of the present invention was 0%. From this, it can be seen that the apparatus of the present invention produces a sound casting free from gas defects.

The above shows that the air leaked from each seal portion does not flow into the cavity during casting by the device of the present invention. This leaked air flow will now be described in comparison with that of a conventional device.

FIG. 3 is an explanatory view showing the flow of leaked air from the seal portion of the surface plate and the stalk, and FIG. 4 is from the seal portion of the chamber and the surface plate. Device, and (b) shows the device of the present invention. In the conventional apparatus, as shown in FIGS. 3 (a) and 4 (a), the air leaked from the seal portion of the chamber 8 and the surface plate 10 or the surface plate 10 and the stalk 12 has a low pressure reducing outlet. 9
Most of the air then flows through the gap between the chamber 8 and the mold 5 as shown by the arrow 21, and a part of the air passes through the gap between the mold 5 and the stalk 12 as shown by the arrow 22 and flows into the cavity 6. It penetrates and flows to the reduced pressure discharge port 9. This is because the air flows from the high pressure side to the low pressure side through the gap having the low ventilation resistance, and the flow of air represented by the arrow 22 causes the generation of gas defects in the casting.

On the other hand, in the device of the present invention shown in FIG. 3 (b) and FIG. 4 (b), the air leaked from each seal part is
As shown by arrows 23 and 24, a large number of vent holes 16 in the surface plate 10
Then, it flows into the box of the surface plate 10 and is discharged from the reduced pressure discharge port 9. Therefore, the leaked air does not flow into the cavity 6, so that no gas defect is left in the casting, and a sound casting can be obtained.

(Advantages of the Invention) With the suction casting apparatus of the present invention, since leaked air does not flow into the cavity, a sound casting without gas defects can be obtained. Also, in the past, even a very small amount of air leak could cause gas defects, so a strict sealing method was required for each sealing part, which was a very difficult sealing method when considering mass production of castings. . However, the apparatus of the present invention enables sufficient casting with a simpler sealing method.

[Brief description of drawings]

FIG. 1 is a sectional view of a suction casting apparatus according to an embodiment of the present invention, FIG. 2 is a sectional view of a conventional suction casting apparatus, and FIGS. 3 and 4 are explanatory views showing the flow of leaked air. , (A) is for a conventional suction casting apparatus, and (b) is for a suction casting apparatus of the present invention. In the figure, 3 ... upper mold, 4 ... lower mold, 5 ... mold, 6 ... cavity, 7 ... gate, 8 ... chamber, 9 ... decompression discharge port, 10 ... surface plate, 11 ... support hole, 12 …… Stoke 13 …… Seal material, 14 …… Insulation furnace 15 …… Molten metal, 16 …… Vent hole

Claims (1)

[Scope of utility model registration request] 1. A surface plate and a chamber mounted on the surface plate,
The mold in the chamber, and a stalk that feeds molten metal from the lower surface to the mold and penetrates the surface plate, the surface plate has a box structure, a reduced pressure exhaust port and a vent hole on the upper surface, the mold Is installed above the upper surface of the surface plate to form a space between the upper surface of the surface plate and the lower surface of the mold, and flows into the chamber from between the chamber and the surface plate and between the surface plate and the stalk. The exhausted air is exhausted from the decompression exhaust port through the ventilation hole on the upper surface of the surface plate without passing through the cavity of the mold, and decompression means for decompressing the inside of the cavity is connected to the decompression exhaust port. And suction casting equipment.