JP3378998B2 - Thin sheet forming method by continuous casting of metal sheet - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuous casting method for a metal plate, and more particularly, to a metal ingot having a smooth surface and a directionally solidified structure. The present invention relates to a method for continuously casting thin metal ingots without breakout. In the present invention, “silicon (S
i) ". 2. Description of the Related Art Conventionally, as a method of manufacturing a plate made of a metal such as Al, Sn, Bi, Zn, etc., a continuous casting method (hereinafter simply referred to as an "OSC method") having an open top horizontal heating mold. ) Has been adopted. (The "OSC method" is
Strip Casting Method ”). Thereby, a long metal having a unidirectionally solidified structure is obtained. Here, the OSC method will be briefly described with reference to FIG. That is, the horizontal heating mold (12) to which the molten metal is supplied is heated by the heating element (30) to a temperature equal to or higher than the solidification temperature of the molten metal. The bottom of the mold (12) is deepest near the inlet (32) into which the molten metal flows. Then, it gradually becomes shallower toward the exit (34), and becomes a horizontal plane (36) from the middle. [0004] Inside the crucible (10) is the crucible (10).
Molten metal (14) melted by heating element (24) covering
Is stored. This molten metal (14)
Is supplied through a hot water supply pipe (16) covered with a heating element (26) and a feed port (32) such that the hot water level (44) is higher than the horizontal plane (36). A dummy plate (38) made of graphite is passed through an outlet (3
4) Insert from the tip of this (40) and horizontal heating mold (1
2) The molten metal (14) supplied inside is brought into contact with the molten metal (14). The gas outlet pipe (4) in the cooling device (18)
Since argon gas is blown toward the upper surface of the graphite dummy plate (38) from 2) to cool the molten metal (14) in contact with the dummy plate (38), the molten metal (14) is cooled and the dummy plate (38) is cooled. Begins to solidify horizontally at the tip (40). Next, the dummy plate (38) is pulled out rearward (to the right in the figure) using a pair of upper and lower pinch rolls (22) (22), so that the dummy plate (38) is pulled out.
Horizontally from the part attached to the tip (40) of the metal plate (2
0) are sequentially formed and gradually become longer. The level of the molten metal surface (44) shifts up and down depending on the insertion amount of the control rod (28), and the distance between the molten metal surface (44) and the horizontal surface (36) is reduced by reducing the insertion amount. . As described above, the thickness of the metal plate to be obtained by operating the control rod (28) can be appropriately changed. [0009] However, the above-mentioned OS
When casting by the C method, particularly when casting a thin plate made of Cu or Si, there is a problem that a breakout occurs. That is, even if the molten metal is supplied to the mold to perform sheet casting, the supplied molten metal gathers in the central portion of the mold and becomes sparse in the peripheral portion due to its large surface tension. If casting was continued in this state, a breakout occurred, and a thin plate-shaped ingot could not be formed. In particular, it occurred remarkably when the width of the mold was 50 mm or less. In order to cast a thin plate-like ingot without causing a breakout, it is necessary to spread a molten metal (molten metal) over the entire surface of the mold so that the molten metal does not gather at the center. In other words, it is necessary to make the molten metal pressure of the metal to be cast equal between the central part and the peripheral part of the mold. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for easily producing a thin ingot in a metal plate casting by the OSC method. Means for Solving the Problems and Actions As a result of intensive studies, the present inventors have added a metal which is considered to be relatively easily oxidized to a molten metal, and added molten metal to the molten metal. It has been found that the above problems can be solved by forming an oxide film of the metal on the surface, and the present invention has been completed. That is, according to the continuous casting method of a metal plate of the present invention, a molten metal is supplied into a mold having at least a part of a bottom surface being a horizontal surface so that a molten metal surface is higher than the horizontal surface. A metal plate is formed on the horizontal surface by directly or indirectly cooling the molten metal above the metal plate, and the metal plate is pulled out horizontally and continuously to form a long metal plate. In a continuous casting method for producing, wherein the molten metal is a metal that is relatively hard to oxidize, a metal that is relatively easily oxidized is added to the molten metal, and an oxide film of the metal is formed inside the mold. This is a method characterized in that it is performed in a state of being formed on a molten metal surface. [0014] The relatively oxidizable metal may be used in the present invention, small standard free energy of oxide formation,
It is necessary that the metal has an equilibrium oxygen partial pressure of 10 ^-20 atm or less at the melting temperature, and that the metal has a low specific gravity so as to easily exist on the surface of the molten metal to be cast. Suitable, specifically, Al, Mg, Ca, L
i . The amount of the metal added to the molten metal is not particularly limited, but is preferably 0.001 to 3 atomic%. When the content is less than 0.001 atomic%, a sufficient amount of oxide film cannot be formed on the molten metal surface in the molten metal, and when the content is more than 3 atomic%, an alloy or an intermetallic compound with the metal to be cast cannot be formed. A possibility arises. The casting speed is not particularly limited.
It is preferably at least 0 mm / min. If the speed is less than 10 mm / min, the formed oxide film flows together with the underlying molten metal, and the meaning of forming the oxide film may be reduced. As a result, the molten metal may collect in the center of the mold, and casting of sheet metal may not be possible. If the cooling capacity is sufficient and the ability to supply the molten metal to the inside of the mold is sufficient, it is preferable to perform the casting at the highest possible casting speed. As the material of the mold, any material such as ceramics and metal may be used as long as it does not react with the molten metal, but ceramics is preferred because it can be easily processed. In particular, easy to mold, easy to obtain,
Graphite and boron nitride, silicon nitride,
It is desirable to use ceramics such as aluminum nitride, aluminum oxide, or a mixed sintered body thereof. By using the template of the present invention, OSC
The reason why the thin plate casting by the method becomes easy is as follows. That is, when the molten metal is spread on the mold, as described above, due to its large surface tension,
The melt pressure at the center of the mold and that at the periphery are greatly different, and the center of the mold is larger. Therefore, if the molten metal pressure is reduced to produce a thin plate ingot, as described above, the molten metal becomes difficult to flow around the mold, that is, the molten metal gathers in the central portion, and as a result, the thin plate ingot becomes In addition, continuous casting becomes difficult due to failure or breakout. A metal which is considered to be relatively easily oxidized is added to the molten metal, and an oxide film of the metal is formed on the molten metal surface of the molten metal. And the pressure of the molten metal at the periphery thereof become uniform, so that there is no possibility that the supplied molten metal is concentrated at the center of the mold, and the thin plate casting by the OSC method becomes easy. The metal which is relatively hard to oxidize in the present invention
(Molten metal) means that it is not oxidized at all in the molten state, or is very little oxidized. Refers to a metal that cannot make the uniformity, specifically, Cu and Si . According to the casting method and the casting mold of the present invention, even a metal such as Cu or Si, which is generally difficult to obtain a thin ingot, can be formed easily and without breakout. Is continuously obtained. Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings, but the present invention is not limited thereto. [Embodiment] FIGS. 1 to 3 are views showing a casting apparatus (top-open horizontal heating mold type continuous casting apparatus) for carrying out the casting method of the present invention. The casting apparatus is roughly divided into a crucible (10) for melting Cu, a horizontal heating mold (12) for casting a Cu plate, and a crucible connecting the crucible (10) and the horizontal heating mold (12). From (10), the molten Cu (1
4) Hot water supply pipe (16) for supplying, horizontal heating mold (1
2) Cooling device (18) provided above and cast C
It comprises a pair of upper and lower pinch rolls (22) (22) for continuously and horizontally pulling out the u-plate (20) rearward. The crucible (10) and the hot water supply pipe (16) are heated to a temperature higher than the melting temperature of Cu by heating elements (24) and (26) provided on the outer periphery thereof, respectively. A control rod (28) having an outer dimension slightly smaller than the inner dimension of the crucible (10) is inserted into the crucible (10), and the control rod (28) is used to control the crucible (10). The molten metal surface of the molten Cu (14) inside is kept constant. In the crucible (10), metal Al (aluminum) was added in an amount of 0.6 atomic% corresponding to the molten Cu (14). As a result, the metal Al was melted, and an oxide thereof was formed on the surface of the molten Cu (14). The horizontal heating mold (12) has side walls (12a) forming left and right side portions thereof and a front wall (12b) forming a front portion.
Both the bottom plate (12c) and the bottom plate (12c) are made of a mixed sintered body of boron nitride and silicon nitride (manufactured by Kawasaki Furnace Materials Co., Ltd.), and the temperature of the mold (12) is below the bottom plate (12c). Controlling the amount of current supplied to the heating element (30)
It is adjusted to a temperature higher than the solidification temperature of the molten Cu. Further, on the crucible (10) side of the bottom plate (12c) in the horizontal heating mold (12), that is, on the molten Cu (14) supply side, the inclination gradually rising from the front wall (12b) of the mold toward the rear. A plane (13) is formed, and a horizontal plane (36) is formed behind the highest ridgeline (15). In order to manufacture a Cu plate, as shown in FIG. 1, first, a graphite dummy plate is prepared in a state where the horizontal heating mold (12) is maintained at a temperature higher than the solidification temperature of Cu by the heating element (30). (38) is the horizontal plane (3
6) Insert the dummy plate (38) through the outlet (34) so as to be placed on top. Thereafter, by operating the control rod (28), the molten Cu (14) is transferred from the crucible (10) into the horizontal heating mold (12) through the hot water supply pipe (16) and the inlet (32). Supply. The molten metal surface (44) of the supplied molten Cu (14) is located above the horizontal surface (36). In addition to the molten Cu (14), the Al oxide formed in the crucible (10) is also supplied to the horizontal heating mold (12) through the hot water supply pipe (16) and the inlet (32).
Get inside. The molten Cu (14) flowing from the inlet (32) of the horizontal heating mold (12) is converted into a graphite dummy plate (38).
Contacts the insertion end (40) of the Argon gas for cooling is blown from the gas blowing pipe (42) of the cooling device (18) to the molten Cu supply side on the upper surface of the graphite dummy plate (38) avoiding the inner wall surface of the horizontal heating mold (12). As a result, the molten Cu (14) in contact with the insertion end (40) of the dummy plate (38) starts to solidify (crystallize) in the horizontal direction from the dummy plate (38). Next, the dummy plate (38) made of graphite is moved rearward (to the right in the drawing) using a pinch roll (22).
The solidified Cu plate (20) can be simultaneously pulled out at the tip (40) of the dummy plate (38) by pulling it out. A Cu plate (20) in the shape of a circle is continuously obtained (see FIG. 3). At this time, the oxide in the mold (12)
The molten C spreads near the solidification interface, that is, near the insertion end (40) of the dummy plate (38) or near the end on the molten metal (14) supply side in the sequentially formed Cu plate (20).
The coating (46) is formed so as to cover the u (14) from above, while the molten Cu (14) flowing into the mold (12) from the inlet (32) is formed of the coating (46). The solidification interface (50) is formed by flowing on the lower side, that is, between the coating and the horizontal surface (36), and the Cu casting mass (20 ') is cast (see FIG. 2). At this time, the depth of the molten Cu (14) from the molten metal surface (44) to the horizontal surface (36) determines the thickness of the manufactured Cu plate (20). Therefore, the thickness of the Cu plate (20) can be changed by changing the insertion amount of the control rod (28) into the crucible (10) and adjusting the molten metal surface (44). Hot surface (44) of molten Cu (14)
The minimum thickness (thickness at the center in the width direction) of the Cu plate (20) stably obtained by forming the oxide film (46) of Al thereon was 1 mm. In this embodiment, the crucible (10) for melting Cu and the horizontal heating mold (12) are connected to the hot water supply pipe (16).
However, these crucibles (10) and the horizontal heating mold (12) may be integrally formed. [Comparative Example] Except that Al was not supplied to the molten Cu, Cu was produced by the OSC method in the same manner as in the above embodiment.
Plate casting was performed. If the degree of insertion of the control rod is reduced in order to reduce the plate thickness, the molten Cu collects at the center of the mold, and the Cu plate cannot be cast. Minimum thickness of Cu plate that can be obtained stably (thickness at center in width direction)
Was 6 mm.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially omitted cross-sectional perspective view showing one example of an open-top horizontal heating mold type continuous casting apparatus used in carrying out a casting method of the present invention. FIG. 2 is a partial longitudinal sectional view showing a state in which an Al oxide film is formed on a molten metal surface. FIG. 3 is a perspective view showing a state where a metal plate is formed in FIG. 1; FIG. 4 is a perspective view showing a state of a conventional continuous casting. [Description of Signs] 10 crucible 12 horizontal heating mold 13 inclined surface 14 molten Cu 15 ridgeline 16 hot water supply pipe 18 cooling device 20 Cu plate 22 pinch roll 24 , 26, 30 Heating element 28 Control rod 32 Inlet 34 (horizontal heating mold) Outlet 36 (horizontal heating mold) Horizontal plane 38 (horizontal heating mold) Dummy plate 40 ... Tip 42 (of the dummy plate)... Gas blowout pipe 44... Molten metal surface 46 (of molten Cu).

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-243247 (JP, A) JP-A-60-191641 (JP, A) JP-A-61-147947 (JP, A) JP-A-61-147947 217538 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B22D 11/00 B22D 11/04 301 B22D 11/108 C30B 29/06 503

Claims (1)

(57) [Claim 1] A molten metal is supplied into a mold having at least a part of a bottom surface being a horizontal surface such that a molten metal surface is higher than the horizontal surface, and a molten metal is provided above the horizontal surface. A metal plate is formed on the horizontal surface by directly or indirectly cooling the molten metal, and the metal plate is horizontally and continuously drawn to produce a long metal plate. A continuous casting method, wherein the molten metal is molten Cu or molten
In the method for forming a thin plate by a casting method of molten Si , a metal which is relatively oxidizable at least one selected from the group consisting of Al, Mg, Ca and Li is added to the molten metal, and an oxide film of the metal is added. In a state where the molten metal is formed on the molten metal surface in the mold.