JP2763708B2 - Cooling mold for continuous casting of pipes with internal fins - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of immersing a lower part of a cooling mold having a mold hole penetrating vertically into a molten metal, injecting the molten metal from a lower opening of the mold hole, and cooling the molten metal from around the mold hole. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling mold for forming a tube having a fin on the inner surface in continuous pulling casting in which a tube is formed by continuous pulling while solidifying.

[0002]

2. Description of the Related Art As shown in FIG. 7, a cooling mold used in a continuous pulling casting apparatus has a material having high heat conductivity and excellent heat resistance in the center of an annular cooling jacket (11). The outer periphery of the jacket (11) is protected by the refractory layer (14). The inner surface of the sleeve (2) forms a mold hole corresponding to the outer diameter of the tube (51) to be manufactured.

The upper part of the cooling mold (1) is exposed from the surface of the molten metal, the lower part is immersed in the molten metal (5), and the molten metal is introduced from the lower opening of the sleeve (2). The cooling water in the cooling jacket (11) surrounding the sleeve (2) causes the molten metal
While cooling and solidifying (5), the solidified layer is sequentially pulled up by a pulling device (7) using a pinch roller or the like, and the tube (51) is continuously cast.

In the continuous casting of the above-mentioned tube, the applicant has previously proposed a cooling mold for casting a tube with an inner fin having a fin on the inner surface of the tube (Japanese Patent Laid-Open No. 3-133).
No. 546). The cooling mold is a sleeve as shown in FIG.
A core (4) is attached to the lower end of (2), and the core (4) and the cylinder (4) fitted in the sleeve concentrically with the sleeve.
Flange (42) extending to the bottom of the sleeve at the bottom of 1)
It has.

An axially extending groove (47) is formed on the outer periphery of the cylindrical body (41) of the core (4), so that the molten metal flows between the core (4) and the lower end inner surface of the sleeve (2). To form a space (40),
A through hole (43) through which the molten metal flows into the space (40) is opened in the flange portion (42).

The molten metal (5) entering the sleeve (2) is cooled and solidified in contact with the sleeve, and while the molten solidified layer is being pulled up, the molten metal adhered to the solidified layer is further solidified in the sleeve (2). The wall thickness increases.

The solidification start end (50) of the solidified layer of the molten metal is
The solidified portion in the space (40) formed by the core (2) and the core (4) is formed by a groove (47) formed on the outer periphery of the cylindrical body (41) of the core (4). ), The solidified portion solidified in the groove (47) grows as the solidified layer is pulled up as described above, and becomes the inner surface fin of the cast pipe body. The cooling mold with a core has a complicated overall structure, and it is difficult to secure the strength of the core. The present invention clarifies a cooling mold for casting an inner finned tube whose core is omitted to simplify the structure.

[0008]

The cooling mold of the present invention has a tubular sleeve (2) formed of a material having high heat conductivity and excellent heat resistance mounted inside an annular water cooling jacket (11). In the cooling mold for pulling continuous casting in which the cooling jacket (11) is protected by the refractory layer (14), a step (6) whose upper part is recessed from the lower part is formed on the inner surface of the sleeve (12). The boundary (61) of (6) periodically changes vertically in the circumferential direction.

[0009]

[Operation and Effect] At the boundary (61) of the step (6), the solidified layer of the molten metal is very easily broken, and therefore, the lower end of the solidified layer of the molten metal is limited to the position of the step.

The solidified layer of the molten metal gradually increases in thickness until it reaches the surface of the molten metal. On the sleeve in contact with the solidified layer of the molten metal, there is formed a step (6) that changes periodically in the circumferential direction up and down. Therefore, at each position in the circumferential direction of the solidified layer of the molten metal,
The time required to reach the molten metal surface is different, and the thickness is different.

That is, the step pattern is reflected in the wall thickness pattern in the casting cross section, and the fin (52) can be formed on the inner surface simultaneously with the casting of the tube (51) shown in FIG. The structure of the cooling mold is simplified by the elimination of the core.

[0012]

FIG. 1 shows a cooling mold (1) of the present invention. The cooling mold (1) surrounds a tubular mold (12) made of copper with an annular cooling jacket (11). The outer periphery of (11) is protected by a refractory layer (14). A water chamber (13) filled with cooling water is formed inside the cooling jacket (11).

The inner surface of the lower end of the copper mold (12) has a concave step (1) over the entire circumference corresponding to the height of the bottom surface of the cooling jacket (11).
0) is formed, and a boundary (15) of the concave step (10) is a cooling lower end for the sleeve (2) described later. Mold (12)
Among them, a tubular sleeve with excellent heat conductivity and good heat resistance
(2) is fitted.

The sleeve (2) of the embodiment is made of graphite at the upper part and boron nitride at the lower part. A step on the lower inner surface of the sleeve made of boron nitride with the upper part recessed from the lower part
(6) is formed, and the boundary (61) of the step portion (6) periodically changes in a wave shape in the circumferential direction in the vertical direction.

The step (6) has a step of 1.0 to 10 mm.
The highest point (61a) of 1) is lower than the bath surface and the lowest point (61a)
b) is about ± 10 mm with respect to the step boundary (14) of the mold (12), that is, the lower end of cooling.

However, the cooling mold (1) is immersed in the molten metal (5) to a depth at which the molten metal surface reaches the upper part of the sleeve (2). Molten metal that has entered the sleeve (2) from the lower end opening of the nozzle (45)
(5) is cooled and solidified in contact with the sleeve (3), and the solidified layer is sequentially pulled up by a pulling device to form a tube.

At the boundary (61) of the step (6), the solidified layer of the molten metal is very easily broken, so that the lower end of pulling up the solidified layer of the molten metal is limited to the step position.

The solidified layer of the molten metal gradually increases in thickness until it reaches the surface of the molten metal. However, a step portion (6) is formed on the sleeve in contact with the solidified layer of the molten metal, which changes periodically up and down in the circumferential direction. Therefore, at each position in the circumferential direction of the solidified layer of the molten metal,
The time required to reach the surface of the molten metal varies, resulting in a difference in wall thickness.

That is, the step pattern is reflected in the thickness pattern in the casting cross section, and the fin (52) can be formed on the inner surface simultaneously with the casting of the tube (51). The configuration is simplified by omitting the core.

FIG. 3 shows another embodiment of the step pattern on the inner surface of the sleeve. FIG. 3A shows a sawtooth pattern, and FIG. 3B shows a pulse waveform pattern. The present invention is not limited to the configuration of the above-described embodiment, and it goes without saying that various modifications can be made within the scope described in the claims.

[Brief description of the drawings]

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

FIG. 2 is a perspective view in which a part of a sleeve is broken.

FIG. 3 is an explanatory view of another embodiment of the pattern of the step on the inner surface of the sleeve.

FIG. 4 is a sectional view of a tube cast by the cooling mold of FIG. 1;

FIG. 5 is a sectional view of a cooling mold previously proposed by the applicant.

FIG. 6 is an oblique view of the above core.

FIG. 7 is a sectional view of a conventional cooling mold.

[Explanation of symbols]

 (1) Cooling mold (2) Sleeve (6) Step

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) B22D 11/04 115 B22D 11/04 311

Claims (1)

(57) [Claims] 1. A tubular sleeve (2) made of a material having high heat conductivity and excellent heat resistance is mounted inside an annular water cooling jacket (11), and the cooling jacket (11) is refractory layered. (14)
In the cooling mold for continuous continuous casting protected by the above, a step (6) is formed on the inner surface of the sleeve, the upper part of which is recessed from the lower part, and the boundary (61) of the step (6) moves up and down in the circumferential direction. A cooling mold for continuous casting of a tube with an inner fin, which periodically changes.