JPH0780603A - Cooling mold for continuous casting - Google Patents

Abstract

(57) [Summary] [Purpose] Prevents breakage of the molten metal solidified layer in pulling continuous casting. [Structure] In a cooling continuous casting casting mold in which a tubular sleeve 2 is mounted inside an annular cooling jacket 11 and the cooling jacket 11 is protected by a refractory layer 14, the inner diameter is adjacent to the lower end of the sleeve 2. A ring 6 having a diameter smaller than the sleeve inner diameter and an outer diameter larger than the sleeve inner diameter is provided concentrically with the sleeve, and the height of the upper surface of the ring 6 is located near the height of the bottom surface of the cooling jacket 11. Since a step is formed between the ring 6 and the inner surface of the sleeve 2, the pull-up break position of the molten metal solidified layer is limited to the lower end position of the sleeve 2, and the pull-up break position is always constant. Sleeve temperature,
Even if the temperature of the molten metal and the solidification state of the molten metal change to some extent, the pulling lower end position does not move, and it is possible to prevent interruption of continuous casting due to breakout of the molten metal solidified layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention immerses 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 penetrate from the lower opening of the mold hole and cool the molten metal from the periphery of the mold hole. ,
The present invention relates to a cooling mold used for pulling continuous casting in which a tube is formed by intermittently pulling up while solidifying.

[0002]

2. Description of the Related Art As shown in FIG. 6, a cooling mold used in a pulling continuous casting apparatus is a material having high heat conductivity and excellent heat resistance in the central portion of an annular cooling jacket (11). The tubular sleeve (2) formed in (1) is attached, and the outer periphery of the jacket (11) is protected by the refractory layer (14). The inner surface of the sleeve (2) forms a die hole corresponding to the outer diameter of the pipe body (51) to be manufactured.

The cooling mold (1) has its upper part exposed from the molten metal surface, its lower part immersed in the molten metal (5), and the molten metal penetrates through the lower opening of the sleeve (2). The cooling water in the cooling jacket (11) surrounding the sleeve (2) causes the molten metal to flow along the mold cavity.
While solidifying (5) by cooling, the solidified layer is intermittently pulled up by a pulling device (7) such as a pinch roller to continuously cast the tubular body (51).

Below the surface of the molten metal in the cooling mold (1), a portion where the molten metal solidifies and can be pulled up, and a portion which is not sufficiently solidified and cannot withstand pulling are continuous, and the sleeve
The part where the inner surface of (2) intersects becomes the pulling lower end of the molten metal solidification layer.

The height position of the pulling lower end is determined by the temperature condition of the sleeve, the temperature of the molten metal and the solidification condition. If these situations change, the pulling lower end position of the molten metal solidification layer moves up and down. Especially in the initial stage of casting, the above-mentioned situation changes greatly, the pulling lower end position tends to move upward, reaches the molten metal surface before reaching a stable state, and there is a problem that a so-called breakout occurs in which continuous casting is interrupted. there were. The present invention reveals a cooled mold that can prevent breakout.

[0006]

According to the cooling mold of the present invention, a tubular sleeve (2) is mounted inside an annular cooling jacket (11),
In a cooling continuous casting casting mold in which the cooling jacket (11) is protected by a refractory layer (14), the inner diameter is smaller than the sleeve inner diameter and the outer diameter is smaller than the sleeve inner diameter adjacent to the lower end of the sleeve (2). A large ring (6) is provided concentrically with the sleeve, the height of the upper surface of the ring (6) being close to the height of the inner bottom surface (10) of the cooling jacket (11).

[0007]

[Operation and effect] The upper surface of the ring (6) is located near the inner bottom surface (10) of the cooling jacket (11),
Since (6) is far from the effective cooling area of the cooling jacket (11), the cooling effect on the ring (6) is small and the ring
(6) The molten metal hardly solidifies on the inner surface.

Even if the molten metal solidifies on the inner surface of the ring (6), the inner surface of the ring (6) is smaller than the inner surface of the sleeve (2), and a step is formed between the ring (6) and the inner surface of the sleeve (2). Since the molten metal solidification layer is pulled up, the fracture position is
Since it is limited to the lower end position of (2), the pulling and breaking position is always constant. Even if the temperature condition of the sleeve, the temperature of the molten metal, and the solidification state of the molten metal change to some extent, the pulling lower end position does not move, and interruption of continuous casting due to breakout of the molten metal solidified layer can be prevented.

[0009]

EXAMPLE FIG. 1 shows a cooling mold (1) according to the present invention. The cooling mold (1) comprises a copper cylindrical mold (12) surrounded by an annular cooling jacket (11), and a jacket. The outer periphery including the upper and lower surfaces of (11) is protected by the refractory layer (14). Water chamber (13) filled with cooling water inside the cooling jacket (11)
Are formed.

The inner surface of the mold (12) has excellent thermal conductivity,
A tubular sleeve (2) having good heat resistance is fitted. In the sleeve (2) of the embodiment, the upper part (21) is made of graphite and the lower part (20) is made of boron nitride, and the lower end is near the height of the inner bottom surface (10) of the cooling jacket (13). It extends to a position slightly lower than the inner bottom surface (10).

A ring (6) which is in contact with the lower end of the sleeve (2) and whose inner diameter is smaller than the inner diameter of the sleeve and whose outer diameter is larger than the inner diameter of the sleeve is provided concentrically with the sleeve. The ring (6) of the embodiment is made of boron nitride, and the upper surface is a horizontal portion (61) orthogonal to the axis of the mold (12).
The width of 1) is about 5 mm and the height is about 20 mm. The refractory layer (14) for protecting the lower surface of the jacket (11) covers the outer circumference and the lower surface of the ring (6) so that the molten metal enters the refractory layer (14).
The hole surface (15) is continuous with the hole surface (60) of the ring (6).

Then, the cooling mold (1) is immersed in the molten metal (5) to such a depth that the molten metal surface reaches above the ring (6) of the sleeve (2). The molten metal (5) that has penetrated into the sleeve (2) through the lower end opening of the mold (1) contacts the sleeve (2) and is cooled and solidified, and this solidified layer (50) is intermittently pulled up by a pulling device. A tube body (51) is formed.

The reason why the pulling lower end position of the molten metal solidification layer (50) is fixed by the ring (6) is as follows. In one cycle of intermittent pulling, first, the solidified layer (50) immediately after pulling
As shown in Fig. 3, if the state of moves to above the ring (6),
The state of the solidified layer (50a) immediately before the next pulling is any one of a to c in FIG. 4 depending on the temperature condition of the sleeve, the temperature of the molten metal, and the solidified state of the molten metal.

That is, in FIG. 4a, the lower end position of the solidification layer (50a) is higher than the horizontal portion (61) of the ring (6). Figure 4b
Is the horizontal portion (61) of the ring (6) at the lower end of the solidified layer (50a).
Matches In FIG. 4c, the lower end position of the solidified layer (50a) is lower than the ring (6).

In the case of FIG. 4b, the lower end position of the solidified layer (50a) coincides with the upper end of the ring (6), and if the solidified layer (50a) is pulled up as it is, the state becomes substantially the same as that of FIG. 3 and there is no problem.

This is rare in the case of FIG. 4c. That is, the ring
The upper surface height of (6) is located near the bottom height of the cooling jacket (11), and the ring (6) is separated from the effective cooling area of the cooling jacket (11). The effect is small, and the molten metal hardly solidifies on the inner surface of the ring (6). In rare cases, the inner surface of the ring (6) is smaller than the inner surface of the sleeve (2) even if the molten metal solidifies on the inner surface of the ring (6). Since there is a step, the pulling and breaking position of the molten metal solidified layer is limited to the lower end position of the sleeve (2), and the same result as in FIG. 4b is obtained.

The problem is that, as shown in FIG. 4a, the lower end of the solidification layer is above the ring (6), which is between the upper end A of the ring (6) and the lower end C of the previous solidification layer. , For example in FIG.
It means that the new solidified layer is broken at point D of
-D 'is the case where the breaking strength is less than the sum of the above items (1) to (4), the inertial force of the solidified layer below point D, the sleeve resistance, and the melt resistance.

When the constriction between D-D 'is remarkable, or when D
When the temperature between −D ′ is higher than that of the other part, there is a possibility that the fracture condition of the solidified layer is satisfied. However, by optimally setting the heat removal cooling condition from the sleeve,
It is possible to prevent breakage of the molten metal solidified layer as in FIG. 4a.

As described above, even if the temperature condition of the sleeve, the temperature of the molten metal, and the solidification state of the molten metal change to some extent, the pulling lower end position does not move, and interruption of continuous casting due to breakout of the molten metal solidified layer can be prevented. The present invention is not limited to the configurations of the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the claims.

[Brief description of drawings]

FIG. 1 is a sectional view of a cooling mold of the present invention.

FIG. 2 is a cross-sectional view near a ring.

FIG. 3 is an explanatory view showing a lower end position of a molten metal solidified layer immediately after one cycle of intermittent pulling is finished.

FIG. 4 is an explanatory view showing a state of a solidified layer next to the state of FIG.

FIG. 5 is an explanatory diagram when the molten metal solidified layer is cut above the ring.

FIG. 6 is a sectional view of a conventional example.

[Explanation of symbols]

 (1) Cooling mold (2) Sleeve (6) Ring

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Itsuo Ohnaka 1-32-21 Higashi Toyonakacho, Toyonaka City, Osaka Prefecture

Claims (1)

[Claims] 1. A tubular sleeve (2) is mounted inside an annular cooling jacket (11), and the cooling jacket (11) is provided with a refractory layer.
In the pulling continuous casting cooling mold protected by (14), the ring (6) contacting the lower end of the sleeve (2) and having an inner diameter smaller than the sleeve inner diameter and an outer diameter larger than the sleeve inner diameter is concentric with the sleeve. A cooling mold for pulling continuous casting in which the upper surface of the ring (6) is located near the inner bottom surface (10) of the cooling jacket (11).