KR101013207B1 - Vacuum melting device of a light metal, and method of vacuum melting using the same - Google Patents

Abstract

The present invention relates to a vacuum dissolving apparatus for light metals and a vacuum dissolving method using the same. More specifically, the vacuum dissolving chamber 100 has a cylindrical pipe shape and a heating means 27 is provided on an outer surface thereof and a stopper 23 at an end thereof. ) Is equipped with an inclined pipe melting furnace 21 formed therein, and the heating means in which the light metal material 40 introduced through the material injection unit 20 is blocked by the stopper 23 in the inclined pipe melting furnace 21. 27), the molten metal 41, which is generated from the point of dissolution of the light metal material 40 to the complete dissolution, is introduced into the molten metal thermal furnace 10 in the form of droplets, which is generated when the light metal is melted. The present invention relates to a vacuum dissolving apparatus for light metals and a vacuum dissolving method using the same, in which a gas to be almost completely separated from the molten metal 41 to produce a cast of pure light metal material.

Description

Vacuum dissolving apparatus for light metals and vacuum dissolving method using same {{Vacuum Melting DEVICE OF A LIGHT METAL, AND METHOD OF VACUUM MELTING USING THE SAME}

The present invention relates to a vacuum dissolving apparatus for light metals and a vacuum dissolving method using the apparatus. More specifically, a magnesium alloy having a high activity in light metals is dissolved in a vacuum state and transported in a state where a vacuum is continuously maintained. The present invention relates to a vacuum dissolving apparatus for light metals capable of maximizing casting characteristics and a vacuum dissolving method using the apparatus.

Light metal is a metal having a lighter specific gravity than titanium (specific gravity 4.5), and typically beryllium (specific gravity 1.85), magnesium (1.74), aluminum (2.7), titanium (4.5), and the like. Mold casting molding methods of die casting, gravity mold casting, squeeze casting, molten metal forging are generally used among the mold casting molding methods of light metals, and magnesium alloys are widely used as raw materials in such mold casting machines.

In particular, magnesium contains about 2.7% of the earth and is the eighth most abundant. Magnesium alloy has a specific gravity of 1.79 ~ 1.81, which is light and has a weight reduction effect of about 70% compared to steel, and is applied to a wide range of fields due to its excellent strength, specific rigidity, castability, machinability, vibration and shock absorption. Usage is on the rise.

Conventional die casting molding methods using light metal alloys include a die casting method, which is divided into a hot chamber method and a cold chamber method. As a patent document, a metal alloy injection molding method and apparatus (Korean Patent No. 10- 0149166, International Publication No. WO 90/09251), roughly classified by Thixomolding method.

In the die casting method, the cold chamber method is to separate the mold casting machine and the light metal melting furnace separately, and pour the molten melt into the injection sleeve of the mold casting machine to press the molten metal with an injection plunger and inject the mold into the mold. It is installed in the melting furnace to press the high temperature molten metal into the mold and molding. The thixomolding method combines conventional plastic injection and die casting of metal, and uses chip-type magnesium alloy as a raw material like plastic injection.

However, in the die casting molding method, there are particular problems in the method of dissolving the magnesium alloy and transferring the material.

In the case of using magnesium alloy in the die casting method, it is necessary to prevent the oxidation of the molten metal because it ignites when dissolved in the air. Therefore, when dissolving magnesium alloy, a large amount of flame retardant flux (SF6 + CO2 mixed gas) or inert gas is injected into the furnace. Flux is a greenhouse gas, which adversely affects the atmospheric environment. In addition, the melting of the magnesium alloy by the die-casting method has a relatively high production cost in terms of production costs, there is a problem that causes air pollution.

The thixomolding method stores magnesium alloy chips in a hopper, feeds chips into a cylinder, moves them forward by the rotation of the screws, simultaneously heats them, turns them into a slurry with a predetermined solid phase rate, and then turns the metal slurry into a high speed screw. It is filled in the molding part of a metal mold | die by forward motion. However, as described above, the raw material in the form of a chip is quite expensive, and scrap (molding defects, runners, gates), which are inevitably generated in metal forming, also cannot be reused, thereby increasing the raw material value.

Accordingly, the present inventors have proposed a number of devices that can perform casting in a vacuum environment, as in the following patent document to solve the above problems, the present invention is a continuous product of the proposed invention as a casting product It is to provide a vacuum dissolving apparatus and method of light metal to form a more pure light metal material.

[Patent Documents]

1. Korean Patent No. 10-0578257; Die Casting Machine

2. Korean Patent No. 10-0550144; Vacuum device of die casting machine

3. US Pat. No. 7,377,303; Die Casting Machine and Casting Method by Thereof Machine

4. Korean Patent No. 10-0572589; Vertical Vacuum Forging Machine

5. Korean Patent No. 10-0572581; Vacuum Gravity Mold Casting Machine

6. Korean Patent No. 10-0572583; Product forming method of vertical vacuum squeeze casting machine and apparatus

An object of the present invention is to maximize the characteristics of the basic vacuum casting by dissolving the light metal in the vacuum state and continuously transport the molten metal, while at the same time almost completely separating the gas generated during the dissolution of light metal from the molten metal (degassing) The present invention provides a vacuum dissolving apparatus for light metals and a vacuum dissolving method using the apparatus, which enable the production of castings made of pure light metal materials.

Vacuum dissolving device of the present invention for achieving the above object, the material injection portion 20 of the light metal material is provided on one side and the melt induction pipe 14 is provided on the lower side of the vacuum dissolution chamber 100 is a vacuum environment ; A molten metal heat-retaining furnace having a molten metal discharge tube 16 mounted on the vacuum melting chamber 100 to be elevated and lowered and connected to the molten metal induction pipe 14 at a lower portion thereof, and having a first heating means 17 on an outer surface thereof. 10; A valve needle rod 12 provided to be lowered to open and close the molten metal discharge tube 16; A pipe melting furnace 21 having one side communicating with the material injection part 20 and the other side being formed in a cylindrical pipe shape so as to be positioned above the molten metal heating furnace 10 and having a second heating means 27 on the outer surface thereof; It is characterized by consisting of a combination.

In a more preferred embodiment, the pipe melting furnace 21 is inclined toward the molten metal heating furnace 10, while the stopper 23 is provided at the outlet of the pipe melting furnace 21 to prevent the movement of the light metal material 40. It features.

In the vacuum dissolution method of the present invention for achieving the above object, the preparation step of the light metal material to inject the light metal material 40 into the material injection portion 20 while maintaining the inside of the vacuum melting chamber 100 in a vacuum environment ( S1); A light metal material input step (S2) of introducing the light metal material 40 into the pipe melting furnace 21 while maintaining the same degree of vacuum between the material injection unit 20 and the vacuum melting chamber 100; Melting and degassing of the light metal material in which the light metal material 40 in the pipe melting furnace 21 is melted while the light metal material is stopped, and the molten melt 41 is gradually introduced into the molten metal thermal furnace 10. S3); A molten metal heating furnace lowering step (S4) of simultaneously lowering the molten metal heating furnace 10 and the valve needle bar 12 so that the molten metal discharge pipe 16 is in close contact with the molten metal induction pipe 14; It is characterized in that consisting of; molten metal discharge step (S5) for elevating the valve needle rod 12 so that the molten metal 41 is discharged to the molten metal induction pipe (14).

According to the vacuum dissolving apparatus of the light metal of the present invention and the vacuum dissolving method using the apparatus, the light metal is dissolved in a vacuum state and is continuously transported while the vacuum is maintained, and the molten metal dissolved in the light metal material is in the form of droplets. Since it is injected into the molten metal furnace, the gas generated during the dissolution of the light metal is almost completely discharged from the molten metal to prepare the casting of ultrapure light metal material, thereby reducing the molding failure rate of the foam or gas line of the cast product. It has an advantageous effect that can reduce the manufacturing cost with productivity.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to the configuration and operation of the vacuum melting apparatus according to the present invention.

1 is a schematic configuration diagram of a light metal vacuum melting apparatus according to an embodiment of the present invention, Figure 2 is a perspective view of a molten metal heating furnace and a pipe melting furnace according to an embodiment of the present invention.

1 and 2, the light metal vacuum dissolving apparatus of the present invention is for dissolving light metals, mainly light metals such as magnesium alloy, in a vacuum environment. It is provided with a molten metal induction pipe 14 at the bottom and the vacuum dissolution chamber 100, the inside is a vacuum environment, the vacuum melting chamber 100 is mounted to be able to move up and down inside the molten metal induction pipe 14 And a molten metal discharge tube 16 connected to the molten metal and having a first heating means 17 on the outer surface thereof, and a valve needle bar 12 capable of lifting up and down to open and close the molten metal discharge tube 16. And a pipe melting furnace 21 having one side communicating with the material injection part 20 and the other side being in the form of a cylindrical pipe so as to be positioned above the molten metal heating furnace 10 and having a second heating means 27 on the outer surface thereof. )

The material inlet 20 is a material inlet tube 24 to guide the light metal material 40, as shown, the inlet pipe valve 26 is installed in front of the material inlet tube 24 and open and close; It is configured to include a side valve 25 which is installed at the rear of the material input pipe 24 and openable and a material loading plunger 30 for introducing the light metal material 40 while being introduced into the material input pipe 24. A pipe (not shown) connected to a vacuum pump (not shown) may be installed above the material input pipe 24 to maintain the inside of the material input pipe 24 in a vacuum state according to a work process.

As shown in FIG. 1, the inlet pipe valve 26 has a hole (not shown) through which the material loading plunger 30 can pass. Therefore, even when the inlet valve 26 is lowered to close the inlet of the material inlet tube 24, the material insertion plunger 30 slides through the inlet tube valve 26 and slides into the material inlet tube 24. I can move it. At this time, when the material loading plunger 30 is inserted into the hole of the inlet pipe valve 26 to close the hole, the inside of the material input pipe 24 may maintain airtightness, which will be described later with reference to FIGS. 5 and 6. This will make it clearer.

The molten metal induction pipe 14 installed in the lower portion of the vacuum melting chamber 100 is provided with a lower valve 15 that can be opened and closed. In this case, the molten metal induction pipe 14 and the molten metal discharge pipe 16 of the molten metal thermal furnace 10 are provided. The connection form of, the lower valve 15 is opened and the molten metal discharge pipe 16 is inserted into the molten metal induction pipe 14 when the molten metal thermal furnace 10 is lowered to maintain close contact. Accordingly, the pure molten metal 41 contained in the molten metal thermal furnace 10 can be safely transferred into the sleeve 150 (see FIGS. 13 to 17) of the mold casting machine under a vacuum environment, and the lower valve 15 is Since it is not in contact with the molten metal 41 can ensure the life and safety of the lower valve (15).

Here, the material injection unit 10 and the molten metal induction pipe 14 and the material injection device published in the vacuum device (Korean Patent No. 10-0550144, US Patent No. 7,377,303) of the die casting machine of Patent Documents 2 and 3 The molten metal induction pipe structure can be replaced, and thus, the detailed configuration and operation method of the material injection unit 20 and the molten metal induction pipe 14 are the same as those disclosed in Patent Documents 1 and 2, and thus, the detailed description thereof. Is omitted since it may obscure the subject matter of the present invention.

The molten metal heating furnace 10 has a funnel-shaped tapping hole 11 formed at a lower portion thereof, and a lower portion of the tapping opening 11 extends downwardly to form a molten metal discharge pipe 16. On the outer surface of the first heating means 17 is installed, and connected to the insulating furnace operating cylinder 19 and the connecting rod 18 formed on the outside of the vacuum melting chamber 100 through the molten heat insulating furnace ( 10) can be lifted or lowered in the vacuum melting chamber 100 by the operation of the thermal furnace operating cylinder (19).

The valve needle bar 12 is connected to the valve needle bar cylinder 13 formed outside the vacuum melting chamber 100 to be lifted or lowered by the operation of the valve needle bar cylinder 13, and the lower end of the valve needle bar 12. Takes the wedge shape. When the valve needle bar 12 is lowered, the wedge-shaped valve needle bar 12 is in close contact with the funnel-shaped tapping hole 11 formed below the molten metal heat furnace 10, and the molten metal 41 accommodated in the molten metal heat furnace 10. ) Does not flow through the tap 11.

On the contrary, when the valve needle bar 12 rises, the molten metal 41 in the molten metal heat-retaining furnace 10 is discharged through the hot water outlet 11, and the molten metal discharge pipe 16 is the molten metal induction pipe 14 when the molten metal 41 is discharged. Since it is to be inserted into the), when lowering the molten metal heating furnace 41, the valve needle bar 12 is lowered in the same way, and after the lowering of the molten metal heating furnace 10 is stopped, the valve needle bar 12 is raised.

The pipe melting furnace 21 is in the form of a cylindrical pipe (pipe), one end is in communication with the outlet side of the material input pipe 24 and the other end is installed so as to be located above the molten metal thermal insulation furnace 10, It is installed to be inclined downward toward the molten metal heating furnace 10 side, and a second heating means 27 is installed on the outer circumferential surface.

In addition, a stopper 23 is provided at the outlet side of the pipe melting furnace 21 to stop the injected light metal material 40, and at the lower end side of the outlet side, a molten metal 41 melted by heating of the second heating means 27 is provided. The molten metal receiving plate 22 is installed to smoothly flow into the molten metal thermal furnace 10.

The second heating means 27 is heated to a temperature higher than the melting point temperature of the light metal material 40 to be melted, and can be replaced by a conventional heater or a high frequency induction coil 50 as shown in FIG. 11.

Since the light metal material 40 is in a solid state at the time of input, the light metal material 40 is stopped in the pipe melting furnace 21 which is caught by the light metal material stopper 23, and the second heating means 27 applies heat to melt the light metal material 40. When the light metal material 40 is gradually dissolved, the molten metal 41 flows into the molten metal thermal furnace 10 via the inclined molten metal receiving plate 22.

That is, since the molten metal 41 is not molten at once, but the molten metal material 40 is gradually melted, the molten metal 41 flowing into the molten metal thermal furnace 10 falls in the form of droplets as drops of water fall. Therefore, since the surface area of the molten metal 41 increases, the internal gas is effectively separated, and furthermore, since the inside of the vacuum melting chamber 100 is in a vacuum state, the molten gas 41 collected in the molten metal thermal furnace 10 is maximized. Pure molten metal having a unique component of the light metal material can be obtained.

According to another aspect of the present invention, as shown in FIG. 12, the molten metal 41 formed by integrally forming the molten metal thermal insulation furnace 10 and the pipe melting furnace 21 flows more smoothly. It is also possible to allow the inflow into the furnace 10.

The first heating means 17 surrounding the molten metal thermal furnace 10 is heated to a temperature slightly lower than the melting point of the molten metal 41 to keep the molten metal 41 from cooling.

3 to 10 is a schematic configuration diagram showing the operation of the light metal vacuum melting apparatus according to an embodiment of the present invention in order, it will be described in detail the vacuum dissolution method using the light metal vacuum dissolving apparatus according to the present invention.

S1: preparation of light metal materials

As shown in FIG. 1, the lower valve 15 and the side valve 25 are closed to open the inlet valve 26 in a state in which the inside of the vacuum melting chamber 100 is evacuated, thereby allowing the light metal material 40 to enter the material input pipe ( 24) positioned at the inlet, the material loading plunger 30 is operated as shown in FIG. 3 to push the light metal material 40 into the material input pipe 24, and then the material loading plunger 30 is retracted as shown in FIG. And close the input pipe valve 26.

S2: Input stage of light metal material

As shown in FIG. 5, the material insertion plunger 30 is advanced to close and seal the plug hole formed in the valve plate of the inlet pipe valve 26, and then vacuum the inside of the material input pipe 24 (described in Patent Documents 1 and 2 above). Then, as shown in FIG. 6, the light metal material 40 is loaded with the light metal material 40 in a state in which the side valve 25 is opened to maintain the same degree of vacuum between the material introduction pipe 24 and the vacuum melting chamber 100. 30) and placed in the inclined pipe melting furnace 21.

Subsequently, when the material loading plunger 30 is retracted and the side valve 25 is closed as shown in FIG. 7, the light metal material 40 slides to the lower portion of the inclined pipe melting furnace 21 and is caught by the stopper 23 to stop the pipe. It is located in the melting furnace 21.

S3: Melting and Degassing of Light Metal Materials

As shown in FIG. 8, the material loading plunger 30 is returned to its original position, the inlet pipe valve 26 is opened, and the temperature of the second heating means 27 of the inclined pipe melting furnace 21 is higher than the melting point temperature inherent to the hard metal material. The molten molten metal 41 is heated to 10 ° C to 100 ° C higher than the first heating means 17 of the molten metal thermal furnace 10 to quickly melt the light metal material 40 to dissolve into the molten metal 41. ) Immediately flows along the slope to the inside of the molten metal thermal furnace 10 via the molten metal receiver 22. At this time, since the molten metal 41 gradually flows down from the dissolved part of the light metal material 40, it flows in the form of droplets like water droplets, thereby increasing the surface area, so that almost all of the gas generated when the light metal is melted. Discharged.

S4: descent stage of the molten metal

When the molten gas 41 is degassed as shown in FIG. 9 is filled in the molten metal thermal insulation furnace 10, the lower valve 15 is opened and the thermal insulation furnace connected through the molten metal thermal insulation furnace 10 and the thermal insulation connecting rod 18 as a medium. By the operation of the cylinder 19, the molten metal heat-retaining furnace 10 is lowered so that the molten metal discharge tube 16 is in close contact with the molten metal induction pipe 14. At this time, the valve needle bar cylinder 13 connected to the valve needle bar 12 is also operated to prevent the melt 41 from flowing into the melt discharge pipe 16.

S5: melt discharge step

Then, as shown in FIG. 10, when the molten metal discharge tube 16 is in close contact with the molten metal induction pipe 14, the valve needle bar 12 is operated to open the valve needle bar 12 upward. It is filled in the sleeve 150 (refer FIG. 13 thru | or FIG. 17) which flowed downward along 14, and was prepared to perform mold casting molding in a vacuum state.

13 is a configuration diagram connected to the vacuum dissolving apparatus and the die casting machine of the present invention, Figure 14 is a configuration diagram connected to the vacuum dissolving apparatus and the vertical vacuum squeeze casting machine of the present invention, Figure 15 is a vacuum melting apparatus and vertical vacuum melt of the present invention 16 is a configuration diagram in which the forging machine is connected, and FIG. 16 is a configuration diagram in which the vacuum melting apparatus and the cold chamber die casting machine are connected, and FIG. 17 is a configuration diagram in which the vacuum melting apparatus and the vacuum gravity mold casting machine are connected.

13 to 17, the vacuum melting apparatus of the present invention can be connected to various types of mold casting molding machine for casting.

The mold casting molding machine includes at least a sleeve 150 and a mold 450, and may further include a molten metal injection hole blocking plunger 300 as shown in FIGS. 13 to 16 according to the characteristics of the apparatus, and also FIGS. 13 and 14. The molten metal pressure plunger 155 may be further provided as shown.

At this time, the vacuum melting die casting machine of Figure 13 may be referred to the configuration of the Republic of Korea Patent No. 10-0578257 as the device proposed by the present invention, the vertical vacuum squeeze casting machine of Figure 14 may refer to the configuration of the Republic of Korea Patent No. 10-0572583 In addition, the vertical vacuum molten forging machine of FIG. 15 may refer to Korean Patent No. 10-0572589, and the vacuum gravity mold casting machine of FIG. 17 may refer to the configuration of Korean Patent No. 10-0572581, each of these mold casting molding machines. Detailed configuration and description of the operation may be omitted since it may obscure the subject matter of the present invention.

As described above, although the present invention has been described with reference to one embodiment shown in the drawings, this is merely an example, and those skilled in the art may make various modifications and other equivalent embodiments therefrom. It will be understood that such modifications and other embodiments are included in the following claims.

1 is a schematic configuration diagram of a light metal vacuum melting apparatus according to an embodiment of the present invention.

Figure 2 is a perspective view of the molten metal heating furnace and pipe melting furnace according to an embodiment of the present invention.

3 to 10 is a schematic configuration showing the operation of the light metal vacuum melting apparatus according to an embodiment of the present invention in order.

11 is a schematic configuration diagram of a light metal vacuum melting apparatus according to another embodiment of the present invention.

12 is a perspective view and a cross-sectional view of the molten metal thermal insulation furnace and the pipe melting furnace according to another embodiment of the present invention.

Figure 13 is a block diagram connected to the vacuum melting apparatus and the die casting machine of the present invention.

14 is a block diagram of the vacuum dissolving device and the vertical vacuum squeeze casting machine of the present invention.

15 is a block diagram of the vacuum melting device and the vertical vacuum forging machine of the present invention connected.

Figure 16 is a block diagram of the vacuum melting apparatus and the cold chamber die casting machine of the present invention connected.

Figure 17 is a block diagram of the vacuum melting apparatus and vacuum gravity mold casting machine of the present invention connected.

<Explanation of the Codes in Drawings>

10 ... Hot Spring Heater 11

12 ... valve needle cylinder 13 ... valve needle cylinder

14 Molten metal induction pipe 15 Lower valve

16 molten metal discharge pipe 17 first heating means

18.Thermostat connecting rod 19 ... Thermostat working cylinder

20.Material injection part 21 ... Pipe melting

22 ... molten metal 23 ... stopper

24 Material feed pipe 25 Side valve

26 Inlet tube valve 27 Second heating means

30 Material loading plunger 40 Light metal material

41 ... molten metal 50 ... high frequency induction coil

100 ... Vacuum melting chamber 150 ... Sleeve

155.Melting pressure plunger

300 ... mold inlet blocking plunger 450 ... Mold

Claims (12)

A vacuum dissolution chamber 100 having a light metal material injection portion 20 on one side and a molten metal induction pipe 14 disposed on a lower side thereof and having a vacuum environment inside; A molten metal heat-retaining furnace having a molten metal discharge tube 16 mounted on the vacuum melting chamber 100 to be elevated and lowered and connected to the molten metal induction pipe 14 at a lower portion thereof, and having a first heating means 17 on an outer surface thereof. 10; A valve needle rod 12 provided to be lowered to open and close the molten metal discharge tube 16; A pipe melting furnace 21 having one side communicating with the material injection part 20 and the other side being formed in a cylindrical pipe shape so as to be positioned above the molten metal heating furnace 10 and having a second heating means 27 on the outer surface thereof; Light metal vacuum melting apparatus, characterized in that consisting of a combination. The method of claim 1, The pipe melting furnace 21 is a vacuum melting apparatus for light metals, characterized in that the inclined downward toward the molten metal heating furnace (10). The method of claim 1, Light dissolution apparatus for a light metal, characterized in that the stopper 23 for preventing the movement of the light metal material 40 at the outlet of the pipe melting furnace 21. The method of claim 1, The apparatus for dissolving light metal, characterized in that the inclined molten metal receiver 22 is provided to guide the molten molten metal at the outlet of the pipe melting furnace 21 into the molten metal heating furnace 10. The method of claim 1, The molten metal heat melting furnace (10) and the pipe melting furnace (21) is a vacuum metal melting apparatus, characterized in that integrally connected. The method of claim 1, A funnel-shaped tapping hole 11 is formed between the bottom of the molten metal heating furnace 10 and the molten metal discharge pipe 16, and a lower end of the valve needle bar 12 is formed in a wedge shape corresponding to the tapping hole 11. A light metal vacuum melting apparatus, characterized in that the mutual sealing is possible. The method of claim 1, The molten metal induction pipe 14 and the molten metal discharge pipe 16 simultaneously lowers the molten metal thermal furnace 10 and the valve needle bar 12 so that the molten metal discharge tube 16 is in close contact with the molten metal induction pipe 14 and then the valve needle bar. A vacuum dissolving apparatus for light metals, characterized in that the structure is opened by lifting (12). The method of claim 1, The second heating means (27) is a vacuum melting apparatus for light metals, characterized in that the heater or high frequency induction coil (50). The method of claim 1, The molten metal heat melting furnace (10) and the pipe melting furnace 21 is a vacuum metal melting apparatus, characterized in that the separation. The method of claim 1, The vacuum melting apparatus of light metal, characterized in that the heating temperature of the pipe melting furnace 21 is higher than 10 ℃ to 100 ℃ than the heating temperature of the molten metal heating furnace (10). A vacuum dissolving method using the apparatus according to any one of claims 1 to 10, Preparing a light metal material (S1) for introducing the light metal material 40 into the material injection unit 20 while maintaining the inside of the vacuum melting chamber 100 in a vacuum environment; A light metal material input step (S2) of introducing the light metal material 40 into the pipe melting furnace 21 while maintaining the same degree of vacuum between the material injection unit 20 and the vacuum melting chamber 100; Melting and degassing of the light metal material in which the light metal material 40 in the pipe melting furnace 21 is melted while the light metal material is stopped and the molten molten metal is gradually introduced into the molten metal thermal furnace 10. (S3); A molten metal heating furnace lowering step (S4) of simultaneously lowering the molten metal heating furnace 10 and the valve needle bar 12 so that the molten metal discharge pipe 16 is in close contact with the molten metal induction pipe 14; A molten metal discharge method (S5) for elevating the valve needle bar (12) so that the molten metal (41) is discharged into the molten metal induction pipe (14). The method of claim 11, In the melting and degassing step (S3) of the light metal material, the molten metal 41 dissolved in the pipe melting furnace 21 in the vacuum melting chamber 100 is introduced into the molten metal thermal furnace 10 by the inclined molten metal receiver 22. A vacuum melting method for light metals, characterized in that flowing down.

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