JPH05146865A - Casting device - Google Patents

Abstract

PURPOSE:To improve the durability of a casting device by eliminating a gate piston having a problem on the durability. CONSTITUTION:In a closed box type holding furnace 15 built in a melting furnace 14, a second vacuum device 17 for evacuating in this holding furnace 15 and a control valve 18 for introducing the air into the holding furnace 15 are connected and the control of molten metal surface ordinarily accomplished with the gate piston 24 is executed by adjusting the pressure in the holding furnace 15 with the second vacuum device 17 or the control valve 18 to eliminate the ordinary gate piston 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting apparatus for filling a cavity with molten metal and casting the same, and more particularly to a casting apparatus for evacuating the cavity before filling the molten metal.

[0002]

2. Description of the Related Art Conventionally, a casting apparatus of this kind has been disclosed in, for example, Japanese Patent Application Laid-Open No. 2-155557 or Japanese Utility Model Publication No. 3-31.
It is known from, for example, Japanese Patent No. 058.

This conventional casting apparatus 20 is equipped with a gate piston 24 for opening and closing the gate 21a of the cavity 21, as shown in FIG.

The gate piston 24 has a cavity 2
1 is slidably mounted in a stalk 23 as a molten metal supply passage that communicates 1 with the melting furnace 22, and moves downward in the drawing when the vacuum device 26 evacuates the cavity 21. The spout 21 of the cavity 21
a is closed so that the cavity 21
The cavity 21 is evacuated after being isolated from the cavity.

On the other hand, in parallel with the evacuation of the cavity 21, the pressurizing device 25 is operated and the holding furnace 27 in the form of a closed box is formed.
The molten metal W in the melting furnace 22 installed inside is pressurized, so that the molten metal W rises in the stalk 23 against gravity and is brought into contact with the lower surface of the gate piston 24.

Here, the gate piston 24 is provided with a vent hole 24a for communicating the inside of the stalk 23 with the atmosphere, and the fluidity of the molten metal in the stalk 23 is secured by the vent hole 24a. .. That is, when the molten metal W rises in the stalk 23, the air in the stalk 23 is exhausted through the air holes 24a, whereby the molten metal W smoothly rises in the stalk 23 and the molten metal W is melted in the melting furnace. At the time of returning to 22, the atmospheric pressure is applied to the surface of the molten metal W through the vent holes 24a, whereby the molten metal W smoothly descends in the stalk 23.

When the degree of vacuum in the cavity 21 reaches a predetermined value, the gate piston 24 is moved upward in the drawing to open the sprue 21a. At this time, the pressure in the cavity 21 and the melting furnace 22 Due to the pressure difference from the pressure applied to the molten metal W, the molten metal W is quickly filled in the cavity 21 through the gate 21a.

In this way, by moving the gate piston 24 up and down to open and close the gate 21a, the cavity 2
During the evacuation of No. 1, the molten metal W is held in a waiting state immediately before the sprue 21a so that the molten metal W does not flow into the cavity 21, while the molten metal W is kept after the evacuation of the cavity 21 is completed. The cavity 21 could be filled quickly.

[0009]

However, the gate piston 24 has a problem in durability for the reasons described below.

That is, the gate piston 24 shields the sprue 21a of the cavity 21 and closes the same.
Since the gate piston 24 is heated to a high temperature at the time of filling the cavity 21 with the molten metal, the above-mentioned sealing property is ensured at a high temperature. Need to

On the other hand, since the gate piston 24 needs to slide in the stalk 23, it is necessary to provide a certain gap between the gate piston 24 and the inner wall of the stalk 23. In contrast, contradictory functions such as sealability and slidability at high temperatures are required.

Further, the vent hole 24a provided in the gate piston 24 is formed with a small diameter so that the molten metal W does not pass through, but the lower surface of the gate piston 24 is filled with the high temperature molten metal W. Since it is exposed, this vent hole 24a thermally expands, and the molten metal W flows into and solidifies there. Eventually, this vent hole 24a is clogged and its breathability deteriorates, and eventually the fluidity of the molten metal W is increased. It will cause trouble. Therefore, it is necessary to reliably prevent clogging in the ventilation hole 24a while ensuring sufficient ventilation.

As described above, conventionally, the gate piston 24 is required to have contradictory functions such as sealing property and slidability at high temperature, or air permeability of the vent hole 24a and prevention of clogging. Therefore, it is unavoidable that the structure becomes complicated, and therefore there is a problem in its durability, and eventually the durability of the casting apparatus 20 is impaired.

The present invention has been made in view of this problem.
The object is to improve the durability of a casting device by solving the problems associated with conventional gate pistons.

[0015]

The present invention is intended to improve the durability of a casting apparatus by eliminating the conventional gate piston, and complements the function of this conventional gate piston. Therefore, the present invention provides a movable mold and a fixed mold that form a cavity when the mold is clamped, a first vacuum device for evacuating the inside of the cavity, a melting furnace in which molten metal is stored, the melting furnace, and the melting furnace. A stalk that communicates with the cavity, a closed box-shaped holding furnace in which the melting furnace is installed, a second vacuum device for evacuating the inside of the holding furnace, and the inside of the holding furnace that communicates with the atmosphere. The casting apparatus is provided with a control valve for

[0016]

According to the above structure, the molten metal is filled in the cavity as follows. First, the first and second vacuum devices are simultaneously operated to simultaneously evacuate the inside of the cavity and the inside of the holding furnace. At this time, by drawing a vacuum between the cavity and the holding furnace while maintaining a constant pressure difference, the molten metal rises in the stalk and reaches just before the gate of the cavity. That is, the state of waiting for filling is maintained.

Next, when the degree of vacuum in the cavity reaches a predetermined value, the control valve is opened to introduce air into the holding furnace, whereby the pressure applied to the molten metal surface in the melting furnace. Increase the pressure. At this time, the molten metal is quickly filled into the cavity through the sprue due to the newly generated pressure difference between the cavity and the holding furnace.

By controlling the pressure in the holding furnace in this way, when the cavity is evacuated, the molten metal reaches the position just before the sprue and is held in a waiting state for filling, and the inside of the cavity is sufficiently filled. After being evacuated, the molten metal is quickly filled into the cavity from the waiting state, so that the function of the conventional gate piston is complemented, and thus the conventional gate piston is unnecessary.

[0019]

EXAMPLE An example of the present invention will be described below with reference to FIG. FIG. 1 shows the entire casting apparatus 1 of this example in a mold clamped state. In this example, a casting apparatus of the type in which the molten metal filled in the cavity 5 is pressurized and the molten metal W is cooled and solidified in this pressurized state is described as an example.
In the figure, the pressure device for that purpose is omitted.

The present apparatus 1 has a main body composed of a movable upper mold 2 and a fixed lower mold 3, and a molten metal W in the main body.
And a molten metal supply source 4 for supplying
The main body and the molten metal supply source 4 are connected by a stalk 13 as a molten metal supply passage.

The upper die 2 is attached to the elevating device 2b via the plate 2a so as to elevate and lower with a constant stroke. The lower die 3 is fixed to the fixed plate 3a. The upper and lower molds 2 and 3 are clamped to form a cavity 5.

A hollow portion 10 is formed in the upper mold 2,
A first vacuum device 6 is connected to the hollow portion 10. Further, the hollow portion 10 and the cavity 5 are communicated with each other by an air passage (not shown). When the upper and lower molds 2 and 3 are clamped and the first vacuum device 6 is operated, the inside of the cavity 5 is closed. It is designed to be evacuated.

Reference numeral 11 in the figure denotes an ejector device for smoothly releasing the solidified molten metal (product) from the upper mold 2 when opening the mold after casting.

The cavities 5 of the upper and lower molds 2 and 3 thus formed are communicated with the molten metal supply source 4 by a stalk 13 serving as a molten metal supply passage.

The stalk 13 is attached so as to pass through substantially the center of the lower die 3 in the vertical direction (gravitational direction) in the figure, and its upper end communicates with the cavity 5 through the sprue 5a in the closed state of the die. When the upper mold 2 is moved upward and the mold is opened, the upper end of the upper mold 2 is opened and opened to the atmosphere.

Although not shown, the stalk 13
A heating device is attached to this so that the molten metal in the stalk 13 is cooled and does not solidify.

The molten metal supply source 4 is a holding furnace 15 in the form of a closed box.
The melting furnace 14 in which the molten metal W is stored is housed therein, and the holding furnace 15 is connected to a second vacuum device 17 via a control valve 18.

Here, in the present embodiment, an example is shown in which a pressurizing device 19 for pressurizing the inside of the holding furnace 15 is further connected to the control valve 18, and the control valve 18 has a "depressurizing position", An example in which the three positions of the "pressurizing position" and the "atmosphere opening position" can be switched is illustrated.

That is, when the control valve 18 is set to the "decompression position" and the second vacuum device 17 is enabled,
The inside of the holding furnace 15 can be evacuated by the second vacuum device 17, while the pressurizing device 1 is set as a “pressurizing position”.
9 is enabled, the pressurizing device 19 can be operated to pressurize the inside of the holding furnace 15. By switching the control valve 18, the molten metal W in the melting furnace 14 can be pressurized.
The pressure applied to the molten metal surface can be reduced or increased above atmospheric pressure. When the control valve 18 is set to the “atmosphere open position”, the inside of the holding furnace 15 is opened to the atmosphere so that the molten metal W in the melting furnace 14 can be loaded with atmospheric pressure.

With respect to the molten metal supply source 4 configured as described above, the stalk 13 is inserted into the holding furnace 15 in a state where airtightness is secured, and is connected in a state of being immersed in the melting furnace 14. The stalk 13 is controlled by operating the second vacuum device 17 or the pressurizing device 19 to control the pressure in the holding furnace 15, that is, the pressure applied to the molten metal W in the melting furnace 14. The position of the molten metal W inside can be arbitrarily controlled.

Next, the casting apparatus 1 configured as described above
A series of casting steps by will be sequentially described. First, prior to filling the molten metal W into the cavity 5, the inside of the cavity 5 is evacuated. The evacuation of the cavity 5 is performed by operating the first vacuum device 6. Then, along with the evacuation of the cavity 5, the evacuation of the holding furnace 15 is performed. The evacuation of the holding furnace 15 is performed by switching the control valve 18 to the "decompression position" and then operating the second vacuum device 17.

The first and second vacuum devices 6 and 17 are simultaneously operated to evacuate the inside of the cavity 5 and the inside of the holding furnace 15 in parallel, whereby the molten metal W is stoke 1.
It is held in a state in which it rises in 3 and reaches just before the sprue 5a of the cavity 5. That is, the pressure in the holding furnace 15 is reduced while maintaining a state higher than the pressure in the cavity 5 by a pressure that can raise the molten metal W to just before the gate 5a. The molten metal W that has risen in the stalk 13 is heated by the heating device attached to the stalk 13 as described above and is kept in a molten state so that it does not solidify.

In this way, if both the inside of the cavity 5 and the inside of the holding furnace 15 are evacuated simultaneously while maintaining a constant pressure difference, and if the inside of the cavity 5 is depressurized to a predetermined vacuum degree, The first and second vacuum devices 6 and 17 are stopped, and the evacuation of both is finished at the same time.

Next, the control valve 18 is operated to the "atmosphere open position" to introduce air into the holding furnace 15, and the melting furnace 1
The pressure applied to the molten metal W in 4 is increased. As a result, a larger pressure difference is generated between the holding furnace 15 and the cavity 5, and the increased pressure difference causes the molten metal W in the filling standby state in the stalk 13 to be quickly filled in the cavity 5. Here, by adjusting the amount of pressure increase in the holding furnace 15 by the control valve 18, the filling rate of the molten metal W into the cavity 5 can be set arbitrarily.

When the cavity 5 is filled with a predetermined amount of the molten metal W, the increased pressure difference is canceled and the flow of the molten metal W is stopped. The molten metal W flowing into the cavity 5 first solidifies from the vicinity of the gate 5a, whereby the molten metal W in the cavity 5 and the molten metal W in the stalk 13 are separated, and thereafter, the molten metal W in the cavity 5 is separated by a pressurizing device (not shown). The molten metal W is pressurized and cooled in this pressurized state for a predetermined time, so that the molten metal W in the cavity 5 is completely solidified and becomes a product.

After that, the mold is opened and the product is taken out. Then, when the product is taken out, the molten metal W remaining in the stalk 13 is loaded with the atmospheric pressure, and thus the residual molten metal W flows downward and is returned to the melting furnace 14.

Here, prior to the mold opening, the holding furnace 15
The internal pressure is applied. That is, the control valve 18 is switched to the "pressurizing position" and the pressurizing device 19 is operated to maintain the pressure inside the holding furnace 15 at a pressure slightly higher than the atmospheric pressure. As a result, the molten metal W in the stalk 13 does not fall freely due to its own weight, but slowly descends and is returned to the melting furnace 14 without involving air. In addition,
Also in this case, the returning speed of the molten metal W can be arbitrarily adjusted by adjusting the amount of pressure applied by the pressure device 19.

Next, when the residual molten metal W is completely returned to the inside of the melting furnace 14, the control valve 18 is once switched to the "atmosphere opening position" and the inside of the holding furnace 15 is opened to the atmosphere. The process ends.

Then, in order to perform casting again, the control valve 1
After switching 8 to the second vacuum device side and closing the mold, the first
If the second vacuum devices 6 and 17 are operated,
It can be performed in the same manner as described above.

This example is constructed as described above,
According to this configuration, the following operational effects are achieved. That is, when the cavity 5 is evacuated, when the cavity 5 is filled, and when the cavity 5 is returned to the melting furnace 14, the level of the molten metal W is conventionally controlled by the gate piston 2
Although it was performed by moving No. 4, according to the casting apparatus 1 of this example, it is performed by controlling the pressure in the holding furnace 15. Therefore, the conventional gate piston 24 is unnecessary, and the casting apparatus 1 can be configured without the gate piston.

Therefore, the durability problem caused by the conventional gate piston 24 is eliminated, and the durability of the casting apparatus 1 can be improved.

Further, in the casting apparatus 1 of this example, since the conventional gate piston is not provided, the structures of the upper and lower molds 2 and 3 can be simplified, and the mold cost can be reduced and the maintainability thereof can be improved. Can be improved.

Further, since both the holding furnace 15 and the cavity 5 are evacuated, the gate gate 24 is used to seal the gate 21a and then the cavity 2 is closed.
As compared with the case where the inside of the chamber 1 is evacuated, the cavity 5 can be evacuated more reliably and quickly.

Further, since the flow rate of the molten metal W can be arbitrarily set by adjusting the pressure (pressure reduction amount) in the holding furnace 15 by the control valve 18, the filling speed of the molten metal W into the cavity 5 can be set. It can be easily controlled, and by filling at an optimum rate, it becomes possible to produce a higher quality cast product.

Similarly, the residual molten metal W in the stalk 13 can be slowly returned to the melting furnace 14 by adjusting the pressure (increase amount) in the holding furnace 15, so that it is naturally dropped by its own weight and returned. As in the case of the above, the molten metal W does not involve gas, and also in this respect, it becomes possible to stably produce a high-quality cast product.

[0046]

According to the present invention, since the function of the conventional gate piston is complemented by adjusting the pressure in the holding furnace, the conventional gate piston can be eliminated, and thus the gate piston can be eliminated. The problem of the durability of the casting apparatus that has been caused is eliminated, and the durability of the casting apparatus can be improved.

[Brief description of drawings]

FIG. 1 is an overall view of a casting apparatus according to this embodiment.

FIG. 2 is an overall view of a conventional casting device.

[Explanation of symbols]

1, 20 ... Casting device 2 ... Upper mold 3 ... Lower mold 4 ... Molten metal supply source 5, 21 ... Cavity 5a, 21a ... Gate 6 ... First vacuum device 10 ... Hollow part 13, 23 ... Stoke (molten metal supply) Passage), 14, 22 ...
Melting furnace 17 ... Second vacuum device 19, 25 ... Pressurizing device 24 ... Gate piston W ... Molten metal

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuhiro Karaki 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Automobile Co., Ltd.

Claims (1)

[Claims] 1. A movable mold and a fixed mold which form a cavity when the mold is clamped, a first vacuum device for evacuating the inside of the cavity, a melting furnace in which molten metal is stored, the melting furnace and the above. A stalk that communicates with the cavity, a closed box-shaped holding furnace in which the melting furnace is installed, a second vacuum device for evacuating the inside of the holding furnace, and the inside of the holding furnace that communicates with the atmosphere. And a control valve for the casting.