KR20010092162A - Vacuum Permanent Mold Casting Equipment - Google Patents

Abstract

PURPOSE: A vacuum gravity casting method is provided to prevent the generation of air bubbles by preventing air and gas from being entered molten metal material. CONSTITUTION: The vacuum gravity casting method is performed by using a mold comprised of an upper mold(3) and a lower mold(4). The inlet part of the mold is provided with a pouring port opening/closing device(2), and on the other hand, the outlet part of the mold is provided with an air flow control valve(8), a vacuum tank(9), and a vacuum pump(10), which are connected in series to close a cavity(5) of the mold, thereby the vacuum condition of the cavity being achieved. The upper mold and the lower mold are covered with an elastic rubber ring or sheet before pouring a molten metal material, and then an O-ring is fitted in grooves formed on the opposite surfaces of the lower mold and a bottom plate to assembly the mold. The mold is closed by locking the pouring port opening/closing device, and then the cavity of the mold vacuumized by opening the valve between the mold and the vacuum tank. When the cavity vacuumized, the molten metal material is poured via a pouring port.

Description

Vacuum gravity casting {Vacuum Permanent Mold Casting Equipment}

The present invention relates to a vacuum gravity casting method for preventing gas and air from being mixed in a molten casting in a gravity casting operation.

Generally, the air and gas in the cavity of the casting mold are removed by the casting mold parting, the riser and the air vent, but the air and the gas are not completely removed. It did not prevent the incorporation into.

In other words, if air and gas in the casting mold cavity are not mixed in the molten metal, bubbles can be prevented. If there is no air and gas pressure in the cavity, the thin part is completely filled to prevent unmolding, thus making a complete casting product. However, in the case of the prior art, as gas and air are mixed in the molten metal, bubbles generated in the main part may cause problems such as unmolded parts that are incompletely filled in thin parts, so that bubbles may appear during machining. In addition, product leakage frequently occurred due to pressure leakage problems. As a result, problems such as deterioration of product quality, increase of inspection cost, and increase of reprocessing cost have occurred.

In order to solve this problem, the present invention is directed to solving this problem by injecting molten metal into a mold cavity.

To this end, the present invention has devised a means capable of sealing all the bonded portions in each component of the mold, and also a process treatment means for sealing.

1 is a schematic illustration showing a vacuum gravity casting process according to the present invention.

2 is a cross-sectional explanatory view of a closed mechanism of the casting mold partition surface according to the present invention.

3 is an explanatory view of a sealing mechanism sealing the mold and the sealing plate according to the present invention.

(Key sign)

2.Inlet opening and closing device 3,4. Upper and lower molds of casting molds

5.Cavity 6.Mill Pin 7.Mill Plate 8.Valve

9.Vacuum tank 11.Casting die face 13.groove 14.O-ring

That is, in the present invention, the casting mold cavity is vacuumed, and a sealing device is installed in the casting mold, and an "O" ring is installed on the joining surfaces of the mold, the upper mold, and the lower mold to seal the mold, and is sealed at the inlet. Of the switchgear, and the airtight device is also attached to the mil pin area.

At this time, it is important to remove the moisture in the air, which causes bubbles, by preheating and drying in parallel with vacuum before pouring molten metal into the mold.

Valves are installed at the air and gas outlets to be connected to the vacuum tank, and the vacuum pump is connected to the vacuum tank, and the inside is vacuumed.

Next, when the molten metal is poured into the inlet and the inlet opening / closing device is opened, the molten metal enters the mold cavity to completely fill the space, and when the mold is opened after the solidification, the product is freed of bubbles and unformed products.

The present invention will be described in more detail with reference to the drawings.

1 is a schematic illustration showing a vacuum gravity casting process according to the present invention.

2 is a cross-sectional explanatory view of a closed mechanism of the casting mold partition surface according to the present invention.

3 is an explanatory view of a sealing mechanism sealing the mold and the sealing plate according to the present invention.

As shown in FIG. 1, in the vacuum gravity casting of the present invention, an inlet opening and closing device (2) capable of adjusting an up and down distance is provided at an inlet part of an upper mold (3) and a lower mold (4) of a casting mold, and a valve is provided at the outlet thereof. (8) and the next vacuum tank 9 and the vacuum pump 10 are connected in series so as to seal the cavity 5 space in the mold.

Here, even if the mold makes the cavity 5 in the casting mold into a vacuum through the vacuum tank 9, if the casting mold cavity 5 is not sealed, there is no vacuum effect. (6) must be sealed.

2 shows the sealing mechanism of the dividing surface 11, in order to seal the casting mold dividing surface 11 between the upper mold 3 and the lower mold 4 of the mold before the molten metal is injected into the cavity 5; It is covered with a seal 12 made of an elastic material such as a heat-resistant rubber or a sheet.

In addition, FIG. 3 shows the complete process by attaching the "O" ring 14 at the appropriate place between the mold lower die 4 and the plate 7 so as to seal the casting mold dividing surface 11 and the mill pin portion 6. It gives a sealing function.

Here, the "O" ring is ring-shaped or spherical, and the groove 13 is formed above and below the surface of a suitable location between the lower mold 4 and the mill plate 7, and the ring-shaped or After inserting the "O" ring as a spherical elastic body and assembling it with a slight pressure, the mold and mold can be completely sealed.

Preheat-dry the mold to 150 ℃ ~ 550 ℃ according to the closed mold thickness and the type of casting product as above. (3) (4) Apply die coat with spray spray or brush and dry it. • Combine the lower molds.

Next, after closing the inlet opening and closing device 2 to seal the molds 3 and 4, the valve 8 between the mold and the vacuum tank is opened to vacuum the inside of the mold cavity. The vacuum at this time is commercially set at approximately -1000 mbar to -950 mbar, and the vacuum in the cavity is thus approximately -700 mbar to -500 mbar, and at least a vacuum of at least -500 mbar is required for good working conditions.

After injecting the molten metal through the inlet, injecting the molten metal into the mold cavity 5 by opening the injector opening and closing device 2, the casting product is taken out of the mold when the inlet solidifies.

The vacuum gravity casting method of the present invention having the above-described configuration is as follows.

That is, as shown in FIG. 1, the vacuum gravity casting first closes the valve 8 and sucks air in the cavity 5 with the vacuum pump 10 to make the vacuum tank 9 into a vacuum.

Then, the mold upper die 3 and the lower mold die 4 are combined, the inlet opening and closing device 2 is closed, and the valve 8 is opened. The mold cavity 5 is connected to the vacuum tank 9 to become a vacuum.

Next, when the molten metal is poured into the inlet 1 and the inlet opening and closing device 2 is opened, the molten metal is filled and filled into the cavity 5 at a short distance. When the molten metal is completely filled in the mold, the valve 8 is opened. Lock and vacuum the tank (9) with a vacuum pump (10).

When the molten metal cools to a solid, the upper mold 3 and the lower mold 4 of the mold are separated, and the cast product is pushed up using the peel pin 6 to take out the solidified product from the mold.

The casting product is removed from the mold, the upper mold (3) and the lower mold (4) are combined together, the inlet opening and closing device (2) is closed, and the inlet (1) is poured into the casting product. When casting is performed while repeating these operations, the product is manufactured without casting bubbles and having a clean surface.

Example

In the following, an embodiment will be described to describe the present invention in more detail.

The casting mold was preheated and dried to 260 ° C to obtain aluminum casting with a thickness of 5mm, and then the upper and lower molds were combined, the inlet opening and closing device was closed, the mold was sealed and the vacuum pump was operated, and the pressure control valve immediately after the mold was opened. Then, the inlet opening and closing device immediately before the mold was opened and 650 ° C. aluminum molten metal was injected.

About 6 minutes after the injection of the molten metal, the product in the mold was withdrawn and the aluminum casting product was randomly cut and examined for appearance. All 10 casting products had no bubbles at all, and the surface was burned. Burnt surface and the like, as well as no thin film or scratch on the surface.

According to the present invention, bubble generation, which is most problematic in non-ferrous castings such as aluminum and copper castings, as well as general castings and steel castings, is hardly seen, and breakthroughs can be suppressed.

Claims (2)

In the vacuum gravity casting method which mainly consists of a mold, a vacuum tank, and a vacuum pump that are fitted into the upper and lower molds, An inlet opening and closing device is installed at the inlet of the mold, and a valve for controlling the flow of air, a vacuum tank, and a vacuum pump are connected in series to seal the cavity space in the mold. To create, In order to seal the cavity space, the upper mold and the lower mold of the mold are covered with a ring or sheet made of elastic rubber before the injection of the molten metal, and a groove is formed on the upper and lower surfaces between the mold and the lower plate of the mold. Insert the “O” ring made of ring or spherical elastic material to fit the mold and assemble the mold, close the inlet opening and closing device to seal the mold, open the valve between the mold and the vacuum tank, and vacuum the inside of the mold cavity. Vacuum gravity casting method to inject molten metal through. The method of claim 1, The hermetically sealed casting mold is preheated to a temperature of 150 ° C. to 550 ° C., and then coated with a die coat, and dried again, and then the upper and lower molds are combined to work. The valve between the mold and the vacuum tank is used. Open the mold cavity to a vacuum, but the vacuum in the mold cavity vacuum gravity casting method characterized in that the setting to-500 mbar or more.