JPH0620636B2 - Suction-type precision casting method and suction-pressure-type precision casting method - Google Patents

Description

The present invention relates to a suction type and suction pressure type precision casting method,
Provided is a method in which a molten metal closes a sprue before gas is introduced into a mold cavity at the time of casting so that the details in the mold cavity can be smoothly rotated.

<Prior Art> The basic technology of the suction-pressure type precision casting method which is the subject of the present invention is, for example, as shown in FIG. 1 or FIG. 3, a melting chamber 1 and a pouring chamber 2 are provided in a casting machine body A. Formed vertically through the partition wall 11, the melting device 36 is provided in the melting chamber 1, and the casting chamber 2 is provided.
An air-permeable mold 14 is pressed against the partition wall 11 by a mold support 16 in an airtight manner, pressurized gas is pressed into the melting chamber 1, and the casting chamber 2 is evacuated to melt the casting material 35. It is of a type that is melted by the device 36 and cast into the mold 14.

Further, the basic technique of the suction type precision casting method is characterized in that the casting chamber 2 is evacuated, and the melting chamber 1 is always provided above the casting chamber 2 to pressurize it, as in the suction pressurizing method. It doesn't need that.

Therefore, for example, a conventional method of a suction pressurization type precision casting method will be described. As shown in FIG. 3, the crucible 13 is housed in the melting chamber 1 and a molten material passage hole 19 formed in the center of the crucible 13 is provided as a partition wall. The casting material 35 is positioned above the melting port 12 of the nozzle 11 so as to communicate therewith, and the casting material 35 is placed on the crucible 13 for casting.

<Problems to be Solved by the Invention> However, in the above-mentioned conventional casting method, when the casting material 35 is melted during casting, the molten metal is melted in the crucible 13.
The pressurized gas reaches the sprue 22 before falling from the sprue 22 to the sprue 22, and the pressurized gas enters the mold cavity 23 of the mold faster than the molten metal.

Therefore, the degree of vacuum in the mold cavity 23 of the mold 14 is momentarily broken, and the pressurized gas acts as a back pressure to prevent the hot water from turning to a thin and wide portion or a thin and long shape portion. It will not be possible to obtain accurate castings in every detail.

This is not limited to the suction pressurizing method as described above, and even in the suction casting method, the vacuum degree in the mold is broken and the molten metal does not reach the details of the mold cavity, resulting in a defective cast product. It is the same in that it can only be obtained.

The present invention is, above all, technically capable of reliably flowing the molten metal into the mold cavity of the mold before the invasion of the gas or the pressurized gas outside the casting chamber to perform good molten metal rotation. It is an issue.

<Means for Solving Problems> Means for achieving the above problems will be described with reference to FIGS. 1 and 2 corresponding to the embodiment.

That is, the collar 50 is integrally projected from the casting material 35, and the melting port 12 is opened in the partition wall 11 so as to correspond to the gate 22 of the mold 14, so that the casting material 35 faces the melting port 12 and the gate 22. The flange 50 of the casting material 35 is attached to the upper surface 51 of the peripheral wall of the sprue 22.
And the peripheral wall surface 52 of the melting port 12 are hermetically sandwiched and fixed, and from this state, the casting material 35 is melted from above by the melting device 36, and the molten metal that has melted to the bottom is instantly melted in the gate 2
2 is closed to prevent the pressurized gas of the melting chamber 1 from entering the mold cavity 23 following the sprue 22, so that the molten metal flows from the spout 22 into the mold cavity 23 without lowering the vacuum degree of the mold cavity 23. A suction pressure type precision casting method characterized in that it smoothly flows into every corner without receiving flow resistance due to back pressure, and the same main structure as the suction pressure type method, but instead of the partition wall Upper wall 11
This is a suction-type precision casting method characterized in that the melting port 12 is opened.

The suction type precision casting method requires casting while sucking the casting chamber 2.

Therefore, it is not essential to provide the melting chamber 1 above the pouring chamber 2, and for example, a melting device (arc discharge electrode, torch, etc.) may be provided at a site open to the atmosphere.

When the melting chamber 1 is provided, the melting chamber 1 may be communicated with the atmosphere and the casting chamber 2 may be sucked, but in short, the casting chamber 2 has a negative pressure with respect to the melting chamber 1. You can set it like this.

The suction in the casting chamber 2 may be continued during the casting, or may be stopped during the casting.

On the other hand, the suction pressurization type precision casting method is a casting method in which pressurized gas is pressed into the melting chamber 1 and the casting chamber 2 is evacuated, and the pressurized gas is compressed air.
An inert gas such as argon or neon may be used.

<Operation> When the casting material 35 is melted by the melting device 36, the casting material 3
No. 5 gradually softens and melts from the upper part to the lower part, but it is a tsuba 50 between the beginning of softening and the complete melting.
While being sandwiched between the peripheral wall upper surface 51 of the sprue 22 and the peripheral wall lower surface 52 of the melting port 12, the central portion thereof hangs down toward the spout 22 due to the positive pressure on the melting chamber 1 side.
It will be in the state of covering 2.

Therefore, the molten metal that has melted to the lower portion can quickly flow into the mold cavity 23 before the pressurized gas, air, or the like enters, and does not reduce the vacuum degree of the mold cavity 23 during casting, The molten metal flows from the spout 22 into the mold cavity 2
There is no flow resistance due to a large back pressure within 3.

<Effects of the Invention> The molten metal can quickly flow into the mold cavity before the pressurized gas, air, etc., and smoothly spread to every corner of the cavity. Also in the method, the casting temperature and the casting timing can be accurately grasped and the molten metal can be satisfactorily performed, and a cast product can be obtained in which the details are precise.

<Example> An apparatus for carrying out the method of the present invention will be described below with reference to FIGS. 1 and 2.

In the figure, reference numeral 1 denotes a hermetically sealed melting chamber, and a hermetically sealed casting chamber 2 is arranged below the melting chamber.

The melting chamber 1 is formed in a closed melting chamber case 3, and an operation port 4 opened on the lateral side of the melting chamber case 3 is hermetically closed by a lid 5.

The pouring chamber 2 is formed in a pouring case 6 having an upper opening.
The casting case 6 is pressed against the melting case 3 by the connecting bolt 7, the height adjusting nut 8, and the swinging locking arm 9, and the melting chamber 2 is kept sealed by the seal ring 10.

When the locking arm 9 is rotated horizontally to be removed from the nut 8, the casting case 6 can be removed from the melting case 3 and the upper surface of the melting chamber 2 can be opened.

A partition wall 11 is integrally formed at the center of the bottom wall of the melting case 3, and a melting port 12 is opened at the center of the partition wall 11.

Further, the mold 14 is arranged under the partition wall 11 in the melting chamber 2 and is air-tightly contacted with the annular seal 15.

The mold 14 is supported by the casting case 6 via a pedestal 16 and a height adjusting bolt 17.

The mold 14 is for dentures, and a shape member 21 made of gypsum and sand is formed in an iron cylinder frame 14a, and a sprue 22 and a molding cavity 23 are formed in the shape member 21.

The gate 22 of the mold 14 is communicated with the melting chamber 1 through the melting port 12 of the partition wall 11, whereby the melting chamber 1 and the pouring chamber 2 are connected.
Communicate with each other through the melting port 12, the sprue 22, the mold cavity 23, the gas vent passage formed by the particle gap of the mold material 21, and the gas vent groove 16a formed on the upper surface of the pedestal 16.

A pressure inert gas injection port 25 is opened on one side of the upper surface of the dissolution chamber 1, and this injection port 25 is connected to a container 27 of argon gas, which is a kind of inert gas, via a flow rate control valve 26.

Further, a gas line 47 is led out from the melting chamber 1 and connected to an argon gas container 27, and the manual opening / closing valve 4 is connected to the gas line 27.
Interpose 6.

A vacuum port 28 is opened at the lower part of one side of the melting chamber 1, and the vacuum port 28 is connected to a vacuum pump 30 via a manual opening / closing valve 41 and a check valve 29.

An inert gas discharge port 31 is opened on one side of the upper surface of the pouring chamber 2, and the discharge port 31 is passed through a throttle adjusting valve 32 and a manual on-off valve 43, and a switching valve 33 to an atmosphere discharge port 34 and a vacuum pump. And 30 are switchably connected.

On the other hand, the casting material 35 is formed in an ingot having a shape in which the central portion is bulged in a spherical shape and the brim 50 is continuously provided on the side portion, and the casting material 35 is received in a state of facing the melting port 12 and the sprue 22. The platform 16 is raised, and the brim 50 is air-tightly sandwiched and fixed between the peripheral wall upper surface 51 of the sprue 22 and the peripheral wall lower surface 52 of the melting port 12.

In the melting chamber 1, a tungsten arc discharge electrode 36 is arranged above the casting material 35 with an appropriate distance, and a power supply 3 is provided between the arc discharge electrode 36 and the casting material 35.
7, a DC voltage or an AC voltage is applied via the voltage regulator 38, the booster 39, the melting case 3, and the partition wall 11.

The arc discharge electrode 36 is fixed to the melting case 3 such that the height of the arc discharge electrode 36 can be adjusted with a height adjusting screw 40.
The height of 6 and the arc discharge voltage adjusted by the voltage adjuster 38 are set as follows.

That is, the arc discharge limit value is the distance between the arc discharge electrode 36 and the casting material 35 at the time when the casting material 35 is melted / heated by the arc discharge and melts down. The arc discharge is set to be interrupted and stopped.

Reference numeral 20 is a sight glass for observing the molten state of the casting material 35.

Next, an example of a procedure for carrying out the suction-pressure type precision casting method using the precision casting apparatus having the above configuration will be described.

This precision casting method includes an inert atmosphere forming step, a material melting step, and a casting step in this order.

In the inert atmosphere forming step, the melting chamber 1 and the pouring chamber 2 are set to an inert atmosphere in order to prevent the casting material 35 from being oxidized and nitrided.

That is, when the switching valve 33 is switched to the vacuum pump 30 side and the manual opening / closing valves 41 and 43 are opened and the vacuum pump 30 is operated, the melting chamber 1 is evacuated through the check valve 29, and the switching valve 33 and the throttle valve 33 are throttled. The inside of the casting chamber 2 and the mold 14 is evacuated through the control valve 32.

Then, when the vacuum is sufficiently reached, the switching valve 33 is closed and the vacuum pump 30 is stopped.

Then, open the flow control valve 26 and the manual opening / closing valve 46,
Argon gas is injected from the argon gas container 27 into the melting chamber 1 and the pouring chamber 2.

At this time, argon gas flows into the melting chamber 1 and the pouring chamber 2, the residual air remaining in both chambers is replaced with argon to further dilute the air concentration, and such evacuation and argon replacement are repeated 3 to 4 times. And increase the concentration of the inert atmosphere.

Next, the manual on-off valves 41 and 46 are closed, and the flow rate adjusting valve 2
6 and the manual on-off valve 43 are opened, and the switching valve 33 is switched to the vacuum pump 30 side to inject the argon gas into the melting chamber 1 and evacuate the casting chamber 2 while the melting chamber 1 is closed. Then, a negative pressure is set, and the following material melting step is started.

That is, when a voltage of a predetermined value is applied between the arc discharge electrode 36 and the casting material 35 to cause an arc discharge, the heat of the arc discharge causes the casting material 35 to soften and melt in order from the upper side to the lower side. .

At that time, since the collar 50 is the slowest to melt, the casting material 35
Between the beginning of softening and the complete dissolution of the tsuba 5
With 0 being sandwiched between the peripheral wall surfaces of both the sprue 22 and the melting port 12, the positive pressure of the melting chamber 1 causes the center portion of the melting point to hang down toward the spout 22 in an arcuate shape. As a result, the gate 22 comes to be closed.

Then, when the casting material 35 is completely melted from the upper portion to the bottom portion, the arc discharge reaches the discharge limit value, is interrupted, and is automatically stopped.

As a result, the completely melted casting material 35 automatically enters the proper temperature range for casting, but at this time, as described above, the melted material 35 hangs down on the sprue 22,
Before the argon gas in the melting chamber 1 reaches the gate 22, the molten metal quickly closes the gate 22, and the mold cavity 2 continues to the gate 22.
Argon gas is prevented from entering 3 and the casting process described below is automatically started.

In the casting step, the entire molten metal is cast into the mold cavity 23 through the sprue 22 while being kept in an appropriate temperature range.

In this case, as described above, since the argon gas does not enter the mold cavity 23, the molten metal does not receive a flow resistance due to a large back pressure from the gate 22 into the mold cavity 23, and the inside of the mold cavity 23 has a high degree of vacuum. Maintained.

Therefore, the molten metal smoothly spreads to the details of the mold cavity 23, that is, the thin and wide portion and the thin and long shape portion,
You can bathe very well.

For this reason, the final cast product can be precisely finished in detail.

[Brief description of drawings]

1 and 2 show an embodiment of the present invention, FIG. 1 is a vertical sectional front view of a precision casting machine for carrying out the method of the present invention, FIG. 2 is a perspective view of the casting machine, and FIG. Is a view corresponding to FIG. 1 showing a conventional example. 1 ... Melting chamber, 2 ... Melting chamber, 11 ... Partition wall (upper wall of casting chamber), 12 ... Melting port, 14 ... Mold, 16 ... Mold pedestal, 22 ... Gate, 23 ...... Mold cavity, 35 ...... Casting material, 36 ...... Melting device, 50 ...... Tsuba, 51 ... 22 peripheral wall upper surface, 52 ... 12 peripheral wall lower surface, A ... casting machine body.

Claims (2)

[Claims] 1. A casting chamber 2 is formed in a casting machine main body A, and an air-permeable mold 14 is pressed in the casting chamber 2 by a mold holder 16 toward an upper wall 11 of the casting chamber in an airtight manner. While pressurizing the pressurizing gas into the melting chamber 1, the casting chamber 2 is evacuated, and the casting material 3
In the suction type precision casting method in which 5 is melted by the melting device 36 and cast into the mold 14, the collar 50 is integrally projected from the casting material 35, and the melting port 12 of the mold 14 is provided on the upper wall 11 of the casting chamber. The casting material 35 is emptied corresponding to the sprue 22 and the melting port 12
The flange 50 of the casting material 35 in a state facing the sprue 22 and the upper surface 51 of the peripheral wall of the spout 22 and the lower surface 52 of the peripheral wall of the melting port 12.
It is clamped and fixed in an airtight manner between
5 is melted from above by the melting device 36, and the molten metal that has melted to the lower portion instantly closes the sprue 22, and the gas outside the casting chamber 2 cannot enter the mold cavity 23 following the sprue 22 from the melting port 12. In this way, the suction is characterized in that the molten metal smoothly flows into the mold cavity 23 from the sprue 22 into the mold cavity 23 without receiving flow resistance due to a large back pressure, without lowering the vacuum degree of the mold cavity 23. Precision casting method 2. A melting chamber 1 and a pouring chamber 2 are vertically formed in a casting machine main body A through a partition wall 11, and a melting device 3 is provided in the melting chamber 1.
6 is provided, and a breathable mold 14 is provided in the casting chamber 2 for the mold cradle 1
At 6, the gas is pressed in an airtight manner toward the partition wall 11, the pressurized gas is injected into the melting chamber 1, the casting chamber 2 is evacuated, and the casting material 35 is melted by the melting device 36 and cast into the mold 14. In the suction pressurization type precision casting method, the collar 50 is integrally projected from the casting material 35, and the melting port 12 is opened in the partition wall 11 so as to correspond to the gate 22 of the mold 14. Tsuba 5 of the casting material 35 facing the 22
0 is sandwiched and fixed in an airtight manner between the peripheral wall upper surface 51 of the sprue 22 and the peripheral wall lower surface 52 of the melting port 12, and from this state, the casting material 35 is melted from above by the melting device 36, The molten metal melted up to instantly blocks the sprue 22 to prevent the pressurized gas of the melting chamber 1 from entering the mold cavity 23 following the sprue 22, and the melt is melted without spoiling the vacuum degree of the mold cavity 23. 22. A suction pressurization type precision casting method, characterized in that it smoothly flows into the mold cavity 23 from every corner without receiving flow resistance due to a large back pressure.