JP2016087680A - Molten metal feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a molten metal feeding device which enables obtainment of a uniform high-quality product with no variation between castings without inflow of impurities and gas into a cavity, and which can increase production efficiency.SOLUTION: A gate for communicating a cavity and a sprue with each other is arranged on a side wall of the sprue, and an upper part of the sprue is provided with a trap with air permeability.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a molten metal supply apparatus, and more particularly, to a molten metal supply apparatus that can prevent impurities such as oxides from flowing into a cavity.

In the low pressure casting method, generally, a holding furnace containing molten metal and a cavity formed in a mold on the holding furnace are communicated with each other by stalk, and the inside of the holding furnace is pressurized to enter the cavity through the stalk. A molten metal is supplied and solidified to obtain a molded product.
Such a low pressure casting method can produce a hollow part by using a core (a mold of a hollow part), and is suitable for producing a part having a complicated shape such as a cylinder head.

However, in the low pressure casting method, the pressurization in the holding furnace for supplying the molten metal is often performed with gas. In addition, since the molten metal in the stalk comes into contact with the air when the mold is opened, the surface of the molten metal is unavoidable. Floats.
These impurities cause deterioration in casting quality, such as an increase in pinholes and shrinkage cavities, and poor hot water circulation due to a decrease in molten metal flowability. For this reason, a filter such as a wire mesh that removes impurities is provided at the gate to prevent impurities from flowing into the mold (for example, Patent Document 1).

According to the filter, impurities such as oxides can be removed. However, since the effective diameter of the spout for supplying the molten metal changes due to the clogging of the filter, even if the molten metal is supplied under pressure under the same conditions, the hot water does not run in the same way.
In particular, in the production of thin-walled products, the molten metal is melted while it is solidified, so variations in the hot water behavior have a significant effect on the quality of the molded product, making it difficult to ensure uniformity among the molded products. is there.
Moreover, it is cumbersome to change the filter for each shot, and productivity is lowered.

  Patent Document 2 describes a low-pressure casting apparatus in which a fan gate communicating with a cavity is provided on a side wall of a gate and a trap space is provided on the upper side of a connection portion between the fan gate and the gate. It is disclosed that impurities such as an oxide film on the surface of the molten metal and a solidified shell of the previous shot are captured in the trap space, and the molten metal having no impurities is fed into the cavity.

JP-A-10-263789 JP 2014-050883 A

However, in the low-pressure casting apparatus described in Patent Document 2, gas may accumulate in the trap space, and impurities may not be sufficiently captured. In addition, when the inside of the cavity is sucked in order to discharge the gas generated by heating the core, etc., smooth the flow of the molten metal, and prevent entrainment of bubbles in the molten metal, Since precise control is difficult, impurities may be sucked into the cavity.

That is, the low pressure casting method in which the molten metal is supplied to the cavity by pressurizing the inside of the holding furnace is performed by pumping gas into the holding furnace. Since the above gas has a large expansion and contraction compared to solid and liquid, and its volume is easy to change, it is difficult to control the molten metal surface with high precision by the amount of gas pumped. Deviation tends to occur at the timing of trapping impurities at

Therefore, the present invention provides a molten metal supply device that can reliably trap impurities floating on the molten metal surface with a trap, and can efficiently produce a uniform and high-quality molded product without variation between molded products. With the goal.
It is another object of the present invention to provide a molten metal supply device that does not suck impurities or gas into the cavity even if the inside of the cavity is sucked.

As a result of intensive studies to achieve the above object, the present inventors have provided a ventilation part in the trap part at the upper part of the gate, so that the gas in the trap space is discharged as the molten metal rises, and impurities on the molten metal surface It was found that traps could be caught with a trap.
Moreover, by providing the ventilation portion, no back pressure is applied, and the molten metal rises smoothly with the pressurization in the holding furnace. Therefore, it has been found that the accuracy of the molten metal surface control is improved, the cavity can be prevented from being sucked before the impurity is trapped by the trap, and the inflow of the impurity into the cavity can be reduced, and the present invention has been completed.

  The present invention is based on the above knowledge, and the molten metal supply apparatus of the present invention connects a gate for communicating the cavity and the gate to the side wall of the gate, and a trap formed on the upper side of the connection portion. A vent is provided.

According to the present invention, the trap provided at the upper part of the gate that captures impurities and the like is provided with a ventilation portion, so that gas does not stay in the trap, and impurities on the molten metal surface can be reliably captured, Inflow of gas and impurities into the cavity can be prevented.
That is, according to the molten metal supply apparatus of the present invention, impurities and the like can be reliably captured by the trap, and the inflow into the cavity is prevented, and there is no need to provide a filter such as a wire mesh, and the effective diameter of the gate is increased. It does not change.
Therefore, there is provided a molten metal supply device that can obtain a high-quality cast product with no variation between shots and ensure uniformity among cast products, and can improve production efficiency.

It is a schematic sectional drawing which shows an example of the low pressure casting apparatus in which the molten metal supply apparatus of this invention is used. It is a schematic sectional drawing which shows an example of the molten metal supply apparatus of this invention. It is a schematic sectional drawing which shows an example of the use condition of the molten metal supply apparatus of this invention. It is a schematic sectional drawing which shows an example of the timing of suction of the molten metal supply apparatus of this invention. It is a schematic sectional drawing which shows an example at the time of molten metal filling in the molten metal supply apparatus of this invention. It is a schematic sectional drawing which shows an example in the state in which the solidification shell in the molten metal supply apparatus of this invention was formed. It is a schematic sectional drawing which shows an example of the state of the mold opening in the molten metal supply apparatus of this invention.

First, a low pressure casting apparatus in which the molten metal supply apparatus of the present invention is used will be described.
FIG. 1 shows a cross-sectional view of an example of a low-pressure casting apparatus. The low-pressure casting apparatus 1 has a gas injection port 3 for pumping an inert gas such as carbon dioxide into a hermetically sealed holding furnace 2, and the lower end of the stalk 4 is immersed in the molten metal in the holding furnace 2. .
In the upper part of the holding furnace 2, a mold 5 comprising a lower mold 5A and an upper mold 5B is arranged. Space portions are respectively formed on the mating surfaces of the lower mold 5A and the upper mold 5B. By overlapping the lower mold 5A and the upper mold 5B, a cavity 6 in the shape of a cast product is formed.
A gate 7 is provided at the upper end of the stalk 4, and a gate 8 communicating with the cavity 6 is provided on the side wall of the gate 7.
The upper mold 5B may be provided with a suction path 9 as required, and the core 10 may be accommodated in the cavity 6 as necessary.

  In such a low-pressure casting apparatus, gas is injected into the holding furnace 2 from the gas injection port 3. With this gas pressure, the molten metal surface in the holding furnace 2 is pushed, the molten metal in the stalk 4 is pushed up, and the molten metal is introduced into the cavity 6 of the mold 5 through the gate 8 provided in the gate 7. Filled. When the molten metal is filled into the cavity 6, the inside of the cavity 6 may be sucked from the suction path 9 provided in the upper mold 5 </ b> B.

After the molten metal filled in the cavity 6 is cooled and solidified, the upper mold 5B is raised to open the cavity 6, and the molded product is taken out from the lower mold 5A.

The molten metal supply apparatus of the present invention is used for the low-pressure casting apparatus as described above. FIG. 2 is a sectional view showing an example of the molten metal supply apparatus of the present invention.

The molten metal supply apparatus according to the present invention is provided between the stalk and the mold, and is formed of a stool piece 7A, 7B that can be divided into upper and lower parts. The gate 8 is provided on the side wall of the gate 7. In the gate 7, a trap 11 space for capturing impurities on the surface of the molten metal is provided above the gate above the connection portion of the gate 8.
A ventilation portion 12 made of porous metal, porous ceramic, or the like is provided above the trap 11, and a suction path 13 connected to a suction pump (not shown) is connected to the ventilation portion 12 as necessary. .

Next, the movement of the molten metal supply in the molten metal supply apparatus of the present invention will be described.
By the first pressurization to the holding furnace, the molten metal 14 in the holding furnace rises in the stalk and reaches the gate 7 as shown in FIG. In the hot water surface near the hot water surface at this time, impurities such as oxides generated by contact between the molten metal and air exist.

  As shown in FIG. 4, when the molten metal 14 reaches the inlet of the gate 8 provided at the gate 7, switching to the second stage pressurization for supplying the molten metal into the cavity 6 in which the filling speed is controlled, The molten metal is filled into the cavity 6.

In the low pressure casting method, the molten metal surface is controlled by pumping a gas having a large volume change, so that it is difficult to strictly control the molten metal surface, and a variation of about several centimeters occurs. At this time, if the impurity or gas contained in the hot water in the vicinity of the hot water surface is switched to the second pressurization or the suction in the cavity 6 is started before the trap 11 captures the impurities or gas, the impurities or gas will be removed from the gate 8. It penetrates into the cavity 6 through, and the quality of the molded product deteriorates.

  In the present invention, since the vent 11 is provided in the trap 11, the gas in the stalk 4 is discharged from the vent 12 as the molten metal rises in the stalk 4. Therefore, no back pressure is applied, and the hot water quickly reaches the trap 11 portion, and impurities and the like are trapped by the trap 11, so that impurities, gases and the like are prevented from flowing into the cavity 6.

  Further, it is preferable to suck the trap 11 at the same time as the molten metal flows into the cavity 6 or before the molten metal flows into the cavity 6.

By sucking the inside of the trap 11 before the molten metal flows into the cavity 6, as shown in FIG. 5, the hot water containing impurities and the like is sucked into the trap part, and the accuracy of the molten metal surface control is low. In addition, the trap 11 can reliably capture impurities. Therefore, since the molten metal with high cleanliness is filled in the cavity 6, it is possible to obtain a high-quality molded article in which impurities and the like are prevented from being mixed.

Further, when the molten metal reaches the upper end of the trap 11, the suction resistance changes. By sucking the inside of the trap 11, it can be detected that the hot water has reached the trap and trapped impurities.
After trapping impurities, switching to the second stage pressurization or starting suction in the cavity 6 can make the hot water behavior uniform and produce a high-quality molded product with no variation. Can be obtained.

When filling of the molten metal into the cavity 6 is completed and the molten metal is cooled to form a solidified shell, as shown in FIG. 6, the solidified shell remains while the trap 11 also captures impurities and the like contained in the hot water. And is fixed to the trap 11.
When the pressurization of the holding furnace 2 is stopped, only a high-purity molten metal that does not contain impurities returns to the holding furnace 2 and impurities contained in the hot water are removed as solidified shells. Impurities such as oxides are not accumulated on the inner surface of the hot water. In addition, since it is not necessary to provide a filter such as a wire mesh, the effective diameter of the gate 7 does not change, and a uniform molded product can be obtained without changing the filling conditions between shots.

The suction of the trap 11 is preferably continued even after the pressurization of the holding furnace 2 is stopped. By continuing to suck the trap 11, it is possible to prevent the solidified shell containing impurities and the like captured by the trap 11 from peeling off and falling into the holding furnace 2 and contaminating the molten metal.

  After the formation of the solidified shell, as the cavity 6 is opened, the gate piece is divided into upper and lower portions and the solidified shell is taken out. At this time, the surface of the molten metal in the stalk 4 is in contact with the air, and an oxide is generated. However, in the present invention, since impurities such as oxide are captured by the trap 11 in the next shot, the impurities may be filled in the cavity 6. Is prevented.

  More preferably, the suction from the trap 11 is continued even after the mold is opened. By continuing to suck the trap 11 until after the mold is opened, as shown in FIG. 7, it is possible to prevent the solidified shell with the solidified shell stuck to the upper gate piece together with the molded product from falling into the stalk and contaminating the molten metal.

DESCRIPTION OF SYMBOLS 1 Low pressure casting apparatus 2 Holding furnace 3 Gas injection port 4 Stoke 5A Lower mold 5B Upper mold 5 Mold 6 Cavity 7 Pouring gate 7A Pouring piece 7B Pouring piece 8 Gate 9 Suction path 10 Core 11 Trap 12 Ventilation part 13 Suction path 14 Molten metal

Claims (5)

A molten metal supply device for supplying molten metal to a cavity,
A gate that connects the cavity and the gate is connected to the side wall of the gate,
There is a trap that traps impurities on the surface of the hot water at the upper part of the upper side of the gate above the connection point between the gate and the gate,
The molten metal supply apparatus, wherein the trap has a ventilation portion.   The molten metal supply device according to claim 1, wherein suction is performed from a vent portion of the trap.   The molten metal supply apparatus according to claim 2, wherein suction from the vent portion of the trap is started before the molten metal flows into the cavity. The molten metal supply apparatus according to claim 2 or 3, wherein suction from the ventilation part of the trap is continued even after pressurization to the holding furnace is stopped. The molten metal supply apparatus according to any one of claims 2 to 4, wherein the suction from the vent portion of the trap is continued even after the mold is opened.

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