JPH0773775B2 - Pull-up continuous casting method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is designed to immerse the lower part of a cooling mold having a mold hole penetrating up and down into the molten metal to allow the molten metal to enter from the lower opening of the mold hole. The present invention relates to a continuous pull-up casting method and apparatus for forming a tubular body by continuously pulling up with a starting rod while cooling and solidifying from the surroundings.

(Prior Art) As shown in FIG. 3, in the pulling continuous casting method, the lower part of the cooling mold (1) is immersed in the molten metal (6), and the mold is opened from the lower opening of the mold hole (11) of the cooling mold (1). The molten metal (6) is introduced into the hole (11).

The starting rod (5) is inserted into the mold cavity (11) from above the cooling mold (1), and the molten metal (6) is attached to the shaft body (3) projecting from the lower end of the rod so that the inside of the mold cavity After the molten metal (6) on the outer periphery of the solidification material (6) is solidified, the starting rod (5) is pulled up by a pulling device (not shown).

The molten metal (6) is cooled by the heat transfer from the mold cavity (11) of the cooling mold (1) and is raised while solidifying, and by balancing the cooling solidification rate and the pulling rate, continuous casting of the tubular body (7) is achieved. Done.

(Problems to be Solved by the Invention) In the pulling continuous casting, when the solidified portion of the molten metal (6) in the cooling mold is attached to the shaft body (3) at the tip of the starting rod (5), and the rod is pulled up. If the molten metal (6) is insufficiently solidified, only the starting rod (5) will be pulled up. That is, it is pulled up empty and the cast pipe (7)
Cannot be manufactured.

Further, if the starting rod (5) is pulled up after the entire molten metal surface in the mold cavity is completely solidified, a solid body is formed instead of the tubular body (7).

The solidification rate of the molten metal (6) is slightly different depending on the molten metal temperature, components, etc., and it is difficult to pull up the starting rod (5).

The present invention discloses a pulling continuous casting method and apparatus capable of solving the above problems by providing an auxiliary starting rod below the starting rod.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a hollow auxiliary rod (4) having a lower end opened and an upper part openably closed at the lower part of a starting rod (5), The lower part of the auxiliary rod is concentric with the mold hole (11) and is immersed in the molten metal in the mold hole (11) to cool and solidify the molten metal between the auxiliary rod (4) and the inner surface of the mold hole (4). ) Is opened to allow the inside of the auxiliary rod (4) to communicate with the atmosphere,
The starting rod (5) is continuously and gradually pulled up to form the tubular body (7).

(Operation and effect) When the auxiliary rod (4) is inserted into the die hole (11), the air in the auxiliary rod (4) presses the molten metal surface in the die hole, so the molten metal surface in the auxiliary rod (4) (61a) is the level (6
It is lower than 1a) (Fig. 1).

The molten metal between the auxiliary rod (4) and the mold hole (11) is deprived of heat by the cooling casting, solidifies in a short time, solidifies and contracts to separate from the inner surface of the mold hole, and is integrated with the auxiliary rod (4). To join.

The auxiliary rod (4) is inserted in the center of the mold hole and is separated from the inner surface of the mold hole, and as described above, the molten metal surface (61a) in the auxiliary rod is more than the molten metal surface (61a) outside the rod. Since the temperature is low, even if the molten metal between the auxiliary rod (4) and the die hole (11) solidifies, the molten metal in the rod hardly undergoes heat exchange with the cooling mold and does not solidify.

After the molten metal between the auxiliary rod (4) and the mold cavity (11) has solidified sufficiently to withstand the pulling, the starting rod (5) is gradually pulled up.

By pulling up the starting rod (5), the auxiliary rod (4) and the molten metal solidified layer formed on the outer periphery of the auxiliary rod (4) are also pulled up together.

If it is confirmed that the molten metal solidified layer on the outer periphery of the auxiliary rod (4) is pulled up integrally with the rod, the upper portion of the auxiliary rod (4) is opened and the inside of the auxiliary rod is communicated with the atmosphere. This prevents the unsolidified melt in the auxiliary rod (4) from rising until it balances with the atmospheric pressure, and further prevents the melt in the rod from solidifying to form a solid body (FIG. 2). ).

By continuing to raise the starting rod,
The tubular body (7) can be continuously cast.

(Examples) Hereinafter, examples of the present invention will be described with reference to the drawings, which should not be construed as limiting the invention described in the claims or reducing the scope.

The cooling mold (1) has a mold hole (11) penetrating vertically in the center, and a mold hole wall (12) is surrounded by a water cooling jacket (13) and a refractory material (14).

A starting rod (5) is arranged so as to be able to move up and down just above the mold hole (11) of the cooling mold (1).

The starting rod (5) comprises a hollow cylindrical starting rod body (2), a plurality of shafts (3) projecting downward from the lower end of the body at equal intervals in the circumferential direction, and a shaft (3). ) Between the starting rod (5) and the auxiliary rod (4) concentrically arranged downward.

The auxiliary rod (4) is made of a material that is not affected by the high heat of the molten metal.
It is formed in a cylindrical shape with its upper end closed and its lower end opened.

In the embodiment, the auxiliary rod (4) is made of a material whose main component is silicon, and the rod is fragile and cracks when an impact is applied.

The auxiliary rod (4) is fixed to the shaft body (3) via a stay (31), and the lower end of the auxiliary rod (4) is located below the lower end of the shaft body (3) of the starting rod (5). It is protruding.

However, the lower part of the cooling mold (1) is soaked in the molten metal (6), and the molten metal is made to enter the inside of the mold cavity through the lower opening of the mold cavity (11) of the cooling mold (1).

The starting rod (5) is lowered, and the lower part of the auxiliary rod (4) and the lower part of the shaft body (3) are immersed in the molten metal in the mold (1) concentrically with the mold hole (11).

When the auxiliary rod (4) is inserted into the mold hole (11), the air in the auxiliary rod (4) presses the molten metal surface in the mold hole, so that the molten metal surface (61a) in the auxiliary rod (4) becomes It is lower than the molten metal surface (61b) outside the rod (5) (Fig. 1).

The molten metal between the rod (5) and the mold hole (11) is deprived of heat by the cooling mold, solidifies in a short time, solidifies and contracts and separates from the inner surface of the mold hole, and the auxiliary rod (4) and the shaft ( 3) Joined together.

The auxiliary rod (4) is inserted into the center of the mold cavity (11) and is separated from the inner surface of the mold cavity, and as described above, the molten metal surface (61a) in the auxiliary rod (4) is the outer metal surface of the rod. (61b)
Therefore, even if the molten metal between the auxiliary rod (4) and the mold cavity solidifies, the molten metal in the auxiliary rod (4) and the mold cavity does not solidify.

After the molten metal between the auxiliary rod and the mold cavity is sufficiently solidified to withstand pulling, the starting rod (5) is gradually pulled up.

By pulling up the starting rod (5), the auxiliary rod (4) and the molten metal solidification portion formed on the outer periphery of the auxiliary rod are also pulled up integrally.

If it can be confirmed that the molten metal solidified layer on the outer circumference of the auxiliary rod (4) is pulled up integrally with the rod, the auxiliary rod (4)
The upper part of the auxiliary rod (4) is broken by a hammer or the like so that the inside of the auxiliary rod (4) communicates with the atmosphere.

This prevents the unsolidified melt in the auxiliary rod (4) from rising until it is balanced with atmospheric pressure (Fig. 2).

The pipe body (7) can be continuously cast by continuing to pull up the starting rod (5).

Example Cooling mold Mold hole diameter 62mm Mold hole total length 300mm Auxiliary rod outer diameter 20mm Inner diameter 16mm Total length 200mm Molten metal component (wt%) C Ni Cr Si Mn Fe 0.4 35 25 1.8 1.1 Remainder temperature 1400 ° C Auxiliary rod inside mold hole Immerse at a depth of 150 mm from the surface of the bath, 5
After 10 seconds, pull up the rod at 10 mm / second.

After confirming that the molten metal solidified layer was formed on the outer circumference of the auxiliary rod, the upper end of the auxiliary rod was hammered and broken.

We were able to cast a tube with an outer diameter of 60 mm and a wall thickness of 8 mm.

The outer diameter of the casting tube is smaller than the inner diameter of the die hole because of the solidification shrinkage of the molten metal.

In the practice of the present invention, the auxiliary rod (4) is replaced with the mold cavity (11).
When the molten metal between the die hole and the auxiliary rod is solidified, the upper end of the auxiliary rod may be destroyed and the inside of the auxiliary rod may be communicated with the atmosphere before the auxiliary rod is pulled up.

Further, as a means for communicating the auxiliary rod with the atmosphere, an airtight opening / closing lid may be provided on the upper part of the rod, and the lid may be opened to communicate the inside of the auxiliary rod with the atmosphere.

The present invention is not limited to the above configuration, and it is needless to say that various modifications can be made within the scope of the claims.

[Brief description of drawings]

FIG. 1 is a fracture cross-sectional view of the continuous pull-up casting according to the present invention, FIG. 2 is an explanatory view during the pulling up of a casting tube, and FIG. 3 is a cross-sectional view of a conventional continuous pull-up casting apparatus. (1) …… Cooling mold (2) …… Starting rod body (4) …… Auxiliary rod (5) …… Starting rod

Claims (4)

[Claims] 1. A mold is formed by immersing the lower part of a cooling mold (1) having a mold hole (11) penetrating up and down in a molten metal (6) to allow the molten metal (6) to penetrate from the lower opening of the mold hole (11). In the continuous pull-up casting in which the solidified portion is continuously pulled up by the starting rod (5) to form the tubular body (7) while the molten metal in the hole is cooled and solidified, the solidified portion is formed below the starting rod (5).
A hollow auxiliary rod (4) whose lower end is open and whose upper part is openable is projected downward, and the lower part of the auxiliary rod is immersed in the molten metal in the mold hole (11) concentrically with the mold hole (11). In a state where the molten metal (6) is cooled and solidified between the auxiliary rod (4) and the inner surface of the mold hole, the upper portion of the auxiliary rod (4) is opened, and the inside of the auxiliary rod is communicated with the atmosphere. A continuous pull-up casting method in which the starting rod (5) is continuously and gradually pulled up to form the tubular body (7). 2. The mold (1) is immersed in the lower part of a cooling mold (1) having a mold hole (11) penetrating up and down to allow the melt (6) to enter from the lower opening of the mold hole (11). In continuous pulling casting in which the solidified portion is continuously pulled up by the starting rod (5) to form the tubular body (7) while the molten metal in the hole is cooled and solidified, the starting rod (5) is used as a pulling device. The rod body (2) is connected to the rod body, and an auxiliary rod (4) is provided at the lower part of the rod body so as to project concentrically with the main body. The auxiliary rod has an open bottom end and an openable upper part. Pulling continuous casting equipment. 3. The pull-up continuous casting apparatus according to claim 2, wherein the auxiliary rod (4) is made of a material which is damaged when an impact is applied. 4. A pulling continuous casting apparatus according to claim 2, wherein an airtight opening / closing lid is provided on an upper portion of the auxiliary rod (4).