JPH08218131A - Method and device for adding additive into molten metal - Google Patents

Abstract

PURPOSE: To provide a method and a device for adding various kinds of additives into molten metal, in which even in the case of being a prescribed quantity of additive having a specific property, the accurate charge can be obtd. in a simple structure and also, the charged additive is surely and uniformly dispersed into molten metal. CONSTITUTION: At the time of adding an additive into a molten metal, the molten metal melted in a metal melting furnace 2 is transferred into a holding furnace 3 through a molten metal transferring trough 4 and on the way, the molten additive melted and held with a melt-holding furnace 6 is poured into the molten metal through the inner part of a pouring tube 5 separated from the surrounding atmosphere. Thus, the poured additive is flowed together with the flowed down molten metal and dispersed without affecting to the surrounding atmosphere and transferred to a holding furnace 3 in the following process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an addition method and an addition device for uniformly adding an additive element such as an alloying element or a modifier added to various metals or alloys to a molten metal, The present invention relates to an addition method and an apparatus for uniformly adding an additive material in an accurate additive amount to a molten metal without adding the additive material, which is easily influenced by the surrounding atmosphere of the molten metal, into the molten metal. .

[0002]

2. Description of the Related Art Conventionally, there are many kinds of aluminum alloys used for building materials, but as an alloy suitable for sashes such as entrances and shutters, there is an alloy specified by JIS standard A6063. The aluminum alloy of A6063 is an alloy in which a small amount of magnesium (Mg) and silicon (Si) are added to aluminum (Al), and the extruded product using this alloy has excellent strength, plasticity, cutting resistance, and corrosion resistance. Has particularly good performance.

As a method for producing this aluminum alloy A6063, usually, an aluminum ingot having a weight of 20 kg per piece, an Al-Si alloy ingot having a required weight, and an aluminum profile as an extruded product. Inferior products and scrap materials such as mill ends are charged into the melting furnace at a predetermined weight ratio.

The above-mentioned alloy material charged is heated by a burner in a melting furnace, and Al-Si (1
2 to 13%) alloy starts to melt, and at about 660 ° C., Al ingot starts to melt. These alloy materials are sequentially charged into the melting furnace, and when the last charged alloy material completes melting and becomes a molten metal, the temperature of the molten metal is about 720.
The temperature in the melting furnace reaches as high as 1100 ° C.

The molten metal is heated in the melting furnace for about 1 hour and 30 minutes and transferred from the melting furnace to the holding furnace which is the next step through the transfer gutter. During this transfer, the desired amount of Mg
Is added. Mg is a substance that is very easily oxidized,
When it is put into a melting furnace with an ambient temperature of about 1100 ° C, it often oxidizes to form Mg ₂ O at the same time as it is put, and it often burns instantly, so it is not possible to put an appropriate amount of Mg. However, it is impossible to obtain an aluminum alloy having a desired component ratio.

The molten metal transferred to the holding furnace is heated by a burner and kept at about 700 ° C. The components of the molten metal in the holding furnace are analyzed by a component analyzer, and insufficient components are added based on the results of the analysis to adjust the components. The component ratios of Si and Mg to Al of the aluminum alloy are specified by the standard, and the amounts of Al, Si, and Mg that meet the standards are calculated in advance before being put into the melting furnace, and the calculated amounts are set. While the corresponding Al and Si are charged into the melting furnace, the calculated amount of Mg is also added to the molten metal flowing through the transfer gutter, but the molten metal transferred to the holding furnace is slightly deviated in the component ratio. Therefore, the above-mentioned component ratio is confirmed in the holding furnace and adjusted. In the holding furnace, various slag floating on the surface of the molten metal is removed. The molten metal is kept in the holding furnace at a predetermined temperature for about 20 minutes. At this time, the molten metal in the holding furnace is stirred so as to have a uniform temperature over the entire area.

The molten metal which has been kept warm in the holding furnace and whose components have been adjusted in this manner is then transferred to the molten metal processing apparatus through the transfer gutter. Al-Ti-B alloy is further continuously added to the molten metal flowing through the transfer trough. This Al
The -Ti-B alloy plays a role of a refining agent, and when the molten metal is solidified in the casting process, the crystal grains of the Al alloy are refined.

The molten metal processing apparatus has a molten metal pool inside,
Inert gas (argon gas) is spouted into the molten metal in the form of bubbles from the tip of the rotating shaft that agitates the molten metal in the pool, and hydrogen molecules present in the molten metal are taken in and discharged together with the inert gas to the outside of the molten metal. . If hydrogen molecules are present in the molten metal, they will remain as bubbles in the billet after solidification in the step of casting the molten metal, forming voids inside the billet. As a result, the aluminum profile extruded from such a billet is roughened and streaked.

The molten metal degassed as described above is sent to the next casting step and cast into a round bar-shaped Al alloy billet having a predetermined length. For example, in vertical casting,
Continuously pouring molten metal into the mold from above, spraying water on the surface of the billet that passed through the mold to solidify by cooling, and sending the solidified portion sequentially downward, a continuous long billet can be obtained. .

Subsequently, the cast Al alloy billet is introduced into a soaking furnace, and the components are homogenized. The inside of the soaking furnace is divided into a heating region and a soaking region. In the heating region, the Al alloy billet is heated to about 600 to 610 ° C. to form a solid solution with crystal grains that have crystallized, and then the soaking is performed. Transferred to the area and left at a temperature of about 580 ℃ for a certain period of time,
While keeping the Al alloy billet in a solid solution state, the coarsely crystallized Mg ₂ Si compound is melted, and the component flow generated by this melting is used to distribute the Mg ₂ Si compound evenly inside the Al alloy billet. To spread without

The Al alloy billet which has passed a predetermined soaking time is taken out from the soaking furnace and is gradually cooled by blowing air. Here, rapid cooling by water cooling is a coarse M
The g ₂ Si compound was crystallized, and the Mg ₂ Si compound was not evenly dispersed inside the Al alloy billet, and the strength was high.
It has poor plasticity and is easily broken. On the other hand, when gradually cooled as described above, fine Mg ₂ Si compounds are extruded and the Mg ₂ Si compounds are evenly distributed inside the Al alloy billet, increasing the strength of the profile and further improving the plasticity. As a result, a high-quality Al alloy billet that is hard to break is obtained.

[0012]

As is clear from the above description, in order to obtain a high quality alloy, it is necessary to strictly control the amount of the additive added to the alloy. When the additive is a chemically and thermally stable material, it is relatively easy to control the amount added, but when the additive is highly oxidizable like Mg and is easily burned, for example, As described above, it is impossible to charge the melting furnace in a high temperature atmosphere, and it is necessary to avoid contact with air as much as possible. Therefore, for example, Mg
It is also possible to send the powder into the molten metal through a pipe installed inside the transfer gutter outside the melting furnace. However, as mentioned above, Mg easily burns, and there is a high risk of dust explosion, which is a management point of view. It cannot be adopted immediately. There are many kinds of additive materials having such physical properties.

From this point of view, it is considered effective to make Mg in the form of a lump (ingot) having a predetermined weight and to put the ingot into the molten metal transferred through the transfer trough, but it has been conventionally melted. Although the work of adding Mg to the molten aluminum alloy is performed manually, the surrounding temperature of the transfer gutter is outside the furnace and the ambient temperature is considerably lower than that inside the melting furnace, but it is still high for workers. The work environment was not good. In addition, addition of Mg to the molten metal flowing through the transfer trough is done by introducing massive Mg ingot (ingot), and the molten metal is scattered at the time of introducing the Mg ingot, which causes many problems in terms of safety for workers. have.

The specific gravity of Mg is 1.74, and
Since it is a very small value compared to the specific gravity of 2.71,
The injected Mg ingot flows while floating in the molten Al, and the entire Mg ingot does not settle in the molten metal. Therefore, a part of the Mg ingot is exposed to the surrounding atmosphere, and the heat of the molten metal oxidizes the Mg to form the oxide Mg ₂ O.
Therefore, it becomes impossible to secure the set amount of added Mg. In order to supplement the amount of reduction at this time, when the Mg base metal is charged in anticipation of the amount of Mg that is oxidized and lost in advance, waste of Mg is caused and productivity is reduced.

The present invention has been made in view of the above circumstances, and an object thereof is to make it possible to accurately add a predetermined amount of an additive having the above-mentioned physical properties to a molten metal with a simple operation and structure. Another object of the present invention is to provide a method and apparatus for adding various additive materials in which the added additive material is surely and uniformly dispersed in the metal to be added.

[0016]

[Means for Solving the Problems] The above-mentioned object is the first of the present case.
In the method of adding an additive to a molten metal which constitutes the main constitution of the invention, the molten metal melted in a metal melting furnace is transferred to a holding furnace through a melt transfer trough, and the additive is held by a dedicated melting and holding furnace. A metal characterized by maintaining a molten state and injecting the additive molten metal of the additive into the molten metal through an additive injection pipe provided inside the molten metal having an injection port flowing down the transfer gutter. This is achieved by a method of adding an additive to the molten metal. Then, preferably, the melting and holding of the additive is performed by using the exhaust gas of the metal melting furnace as a heat source.

Further, the above object is an apparatus for adding an additive to a molten metal which constitutes the main constitution of the second invention of the present invention,
A melt transfer gutter that connects between the metal melting furnace and the holding furnace, and a melting and holding furnace dedicated to the additive material that is installed around the melt transfer gutter and holds the molten state of the additive material A device for adding an additive to a molten metal, which is connected to a holding furnace and has a melt addition material injection pipe whose inlet is installed up to the inside of the molten metal flowing down the transfer gutter. To be achieved.

A plurality of melting and holding furnaces dedicated to the additive material are installed around the molten metal transfer gutter, and it is possible to inject a plurality of kinds of additive materials into the molten metal at the same time by using each melting and holding furnace. . Further, preferably, the melting and holding furnace for the additive material is provided with an exhaust gas pipe for high-temperature gas discharged from the metal melting furnace, and exhaust heat from the metal melting furnace is used as a heat source of the melting and holding furnace.

The additive may be melted in the melting and holding furnace or may be melted in another dedicated melting furnace and then transferred to the melting and holding furnace.

[0020]

Function: The alloy material in the molten state in the metal melting furnace flows through the transfer gutter and is transferred to the holding furnace. In the present invention, an injection pipe for introducing the additive material is provided in the transfer gutter, and the melted additive material whose melted state is held by a dedicated melting and holding furnace is supplied to the injection pipe. At this time, the injection pipe and the melting and holding furnace dedicated to the additive are hermetically sealed so that outside air does not enter. The molten and retained additive material is injected into the molten metal at a pre-calculated injection flow rate while the molten metal is being transferred through the molten metal transfer trough connecting the metal melting furnace and the holding furnace. Inject automatically through the tube. The additive does not come into contact with outside air during this injection.

The molten additive injected into the molten metal flows in the molten metal transfer trough while diffusing along the flow of the molten metal, and is transferred to the holding furnace in the next step. Moreover, since the additive does not come into contact with the outside air during the transfer of the molten metal, even if the additive is easily affected by the surrounding atmosphere, there is almost no waste of the additive and a desired amount of additive is added. The material is uniformly dispersed in the flow of the melt to be added.

[0022]

The present invention will be described in detail below with reference to the illustrated embodiments. In the illustrated embodiment, the present invention is applied to a vertical continuous casting method of an Al alloy billet that is a raw material for aluminum building material extrusion molding, and an additive is added to add Mg and Si to the molten metal as an additive. It is a device. FIG. 1 is a top view showing the outline of the addition device according to the present invention, FIG. 2 is a perspective view showing a specific example of the addition material injection part forming the main part of the present invention, and FIG. 3 is a vertical cross-section of the same addition material injection part. FIG. 4, FIG. 4 is a cross-sectional view showing an example of the melting furnace for exclusive use of the additive applied to the apparatus of the embodiment, and FIG. 5 is a vertical sectional view of the melting furnace for exclusive use of the additive.

Mg and S as additive materials in the illustrated example
As shown in FIG. 1, the addition device 1 of i is provided with a molten metal transfer gutter 4 for connecting between the metal melting furnace 2 and the holding furnace 3 and the respective inlets 5a and 50a inside the transfer gutter 4. First and second dissolution additive material injection pipes 5, which are arranged as far as possible
50, and the base ends 5b and 50b of the respective injection pipes 5 and 50 are connected to each other, and are provided with Mg and Si-dedicated additive melting and holding furnaces 6 and 60 that are melted and hold a molten state. Note that Si
Since the ingot has a melting point of 1412 ° C., in the additive melting and holding furnace 60 that uses the exhaust gas of the melting furnace as a heat source as in this embodiment, it is difficult to maintain the molten state by Si alone. Therefore, in this embodiment, Al is used as the additive.
-A desired amount of Si alloy is added. Also,
In the illustrated example, a second molten metal transfer gutter 40 is installed between the holding furnace 3 and the casting machine 7, and a degassing device 14 is arranged in the middle of the molten metal transfer gutter 40.

Referring to FIGS. 2 and 3, the Mg and Al
A specific example of the structure of the molten part of the Si alloy will be described. The Mg injection pipe 5 and Al are provided on the side of the molten metal transfer gutter 4.
A substantially L-shaped support arm 10 that simultaneously supports the —Si alloy injection pipe 50 is erected so that a part thereof crosses above the molten metal transfer gutter 4. The molten metal injection ports 5a and 50a of the Mg injection pipe 5 and the Al-Si alloy injection pipe 50 are immersed in the molten metal 9 transferred through the transfer gutter 4, and the tip portions of the molten metal injection ports 5a and 50a are fixed. It is bent in a V shape and is directed in the flow direction of the molten metal 9. The Mg injection tube 5 and A
The base ends 5b and 50b of the l-Si alloy injection pipe 50 are provided with dedicated first and second melting and holding furnaces 6 and 6, as shown in FIGS.
It is connected to the bottom of 60 through a flow meter 11.

As shown in FIG. 1, the first and second melting and holding furnaces 6, 60 are provided side by side on the side of the metal melting furnace 2, and inside the respective melting and holding furnaces 6, 60, the metal melting furnace 2 is provided. The exhaust gas pipe 2a extending from the above is disposed so as to penetrate therethrough. Further, circulation fans 6a and 60a are provided on the ceilings of the melting and holding furnaces 6 and 60, respectively, and a molten metal of Mg and Al-Si alloy is charged to one side wall of the melting and holding furnaces 6 and 60. The charging ports 6b and 60b for opening the charging ports 6b and 60b are connected to the cylinders 12a and 12b.
The opening / closing members 13a and 13b that are operated by are attached.

In the above-mentioned structure, in the illustrated example, a metal melting furnace 2 is used to obtain a raw material of an Al alloy extruded profile of JIS A6063. Therefore, two types of alloy materials, that is, a metal ingot and a defective product such as an aluminum shaped material which is an extruded product, and a scrap material such as a scrap material are charged into the melting furnace 2. The alloy material for one lot is put into the furnace several times. The charged alloy material is heated in the melting furnace, the Al metal starts to melt at about 660 ° C., and when all the alloy materials charged to the melting furnace are in a molten state, they are melted to form a molten metal state. Become. When the required alloy material is in the molten state, the temperature of the molten metal is about 720
C., and the ambient temperature in the furnace reaches 1100.degree.

The alloy material in the molten state in the melting furnace 2 flows through the molten metal transfer gutter 4 and is transferred to the holding furnace 3. In the present invention, the flow rates of the injection amounts of Mg and Al—Si alloy calculated in advance during the flow of the molten metal 9 through the transfer gutter 4 are controlled by the respective flow meters 11 to control the first and second melting and holding furnaces 6. , 60 automatically through the dedicated injection pipes 5, 50 into the molten metal. The additive materials Mg and Al-Si alloy in a molten state injected into the molten metal flow together with the flow of the molten metal, and at the same time diffused uniformly in the molten metal.

Here, since Mg is a metal that is extremely easily oxidized, it is easily oxidized and burned at a high temperature. However, in the present invention, Mg as an additive is melted in advance as described above, and this is transferred to a melting and holding furnace, and then the molten metal transfer gutter is directly transferred through an injection pipe connected to the melting and holding furnace. Since it is injected into the molten metal inside, the dissolved Mg does not come into contact with the external atmosphere at all, and there is no reduction due to oxidation. Further, when the additive material is a solid, it is necessary to set the length of the molten metal transfer gutter in order to secure a melting time in which the molten metal transfer gutter is immersed and melted in the molten metal to be transferred. According to this, since the additive material in the molten state is mixed in the molten metal flowing at a predetermined flow rate and is evenly dispersed in the molten metal along with the flow of the molten metal, the length of the molten metal transfer gutter depends on the flow rate and the type of the molten metal. It can be set to any length without being affected.

In the above embodiment, two melting and holding furnaces 6 for Mg and a melting and holding furnace 60 for Al-Si alloy are provided side by side, but of course, one kind of melting and holding furnace for additive is installed. Alternatively, it is possible to add three or more types of additive holding furnaces for simultaneous addition of multiple types of additive to the molten metal.

[0030]

As is apparent from the above description, according to the method and apparatus for adding an additive to a molten metal of the present invention, the additive in a molten state is added to the molten metal flowing down through the transfer trough. Since it is directly injected through the injection pipe without contacting the atmosphere, the additive material is reliably added according to the setting without being affected by the surrounding atmosphere and reducing the amount, and the molten metal flow is used. Since the molten additive is dispersed in the molten metal, high quality is guaranteed for the final cast product.

[Brief description of drawings]

FIG. 1 is a schematic top view showing a main part of a continuous casting facility equipped with a device for adding an additive, which is a typical embodiment of the present invention.

FIG. 2 is an enlarged perspective view showing an additive material injection portion of the addition device.

FIG. 3 is a vertical sectional view of the injection part.

FIG. 4 is a cross-sectional view showing an example of the internal structure of a melting and holding furnace in the adding apparatus.

FIG. 5 is a vertical sectional view of the melting and holding furnace.

[Explanation of symbols]

 1 Additive material addition device 2 Metal melting furnace 2a Exhaust gas pipe 3 Holding furnace 4,40 Molten metal transfer trough 5,50 (Additive material) injection pipe 5a, 50a Injection port 5b, 50b Base end 6,60 (Additive material) melting and holding furnace 6a, 60a Circulation fan 6b, 60b Input port 7 Casting machine 8 Mg ingot, Al-Si alloy (additive material) 9 Molten metal (additive material) 10 Support arm 11 Flowmeter 12a, 12b Cylinder 13a, 13b Opening / closing member 14 Degassing apparatus

Claims (5)

[Claims] 1. A method of adding an additive (8) to a molten metal (9), wherein the molten metal (9) melted in a melting furnace (2) is transferred to a molten metal transfer gutter.
Transfer to the holding furnace (3) through (4), holding the additive material (8) in a molten state with a dedicated melting and holding furnace (6), and the molten metal (8a) of the additive material (8). ,
The injection port (5a) is characterized in that the injection port (5a) is injected into the molten metal through an additive material injection pipe (5) which is installed inside the molten metal (9) flowing down the transfer gutter (4). A method of adding an additive to a molten metal. 2. The method for adding an additive to a molten metal according to claim 1, wherein the melting and holding of the additive (8) is performed by using the exhaust gas of the melting furnace (2) as a heat source. 3. An apparatus for adding an additive (8) to a molten metal (9), the molten metal transfer trough connecting between the melting furnace (2) and the holding furnace (3).
(4) and the additive material (8) installed around the molten metal transfer gutter (4).
The melting and holding furnace (6) dedicated to the additive material that holds the melting state of the, and the injection port (5a) of the melting and holding furnace (6) connected to the melting and holding furnace (6).
An apparatus for adding an additive to a molten metal, comprising: a melt additive injection pipe (5) which is installed up to the inside of the molten metal (9) flowing down the transfer gutter (4). 4. A melting and holding furnace (60) for exclusive use of a second additive is provided around the molten metal transfer gutter (4) together with a melting and holding furnace (6) for exclusive use of the additive. One end is connected to the melting and holding furnace (60), and its injection port (50a) is installed to the inside of the molten metal (9) flowing down the transfer gutter (4). Claim (3), which is provided with (50)
An apparatus for adding an additive to the molten metal described. 5. The metal melting furnace (2) is provided inside the melting and holding furnace (6) for the additive material and the melting and holding furnace (60) for the second additive material.
An apparatus for adding an additive to the molten metal according to claim 3 or 4, wherein an exhaust gas pipe (7) for high-temperature gas discharged from the tank is provided.