JPH07178513A - Production of pipe having uneven thickness by drawing-up continuous casting - Google Patents

Abstract

PURPOSE:To efficiently form a pipe having uniform outer diameter and uneven thickness by drawing-up continuous casting. CONSTITUTION:A cooling mold surrounding the outer periphery of a heat resistant sleeve 2 formed with a mold hole 20 vertically penetrated with a cooling jacket 3, is exposed from molten metal surface at the upper part thereof and dipped into the molten metal at the lower part thereof to invade the molten metal into the mold hole 20, to continuously cast the pipe by drawing-up the molten metal solidified layer 61 which is solidified by bringing into contact with the mold hole 20. Then, a hollow part is locally formed between the sleeve 2 and the cooling jacket 3 or the thickness of the sleeve is locally changed, etc., so as to form the cooling mold having alternate existences of the high part and the low part of the cooling capacity in the peripheral direction. Such a cooling mold is used and the pipe having uniform outer diameter and uneven thickness is efficiently produced by forming the thick thickness at the high cooling capacity and the thin thickness at the low cooling capacity in the cooling mold.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an uneven wall thickness tube having a uniform outer diameter by pulling continuous casting.

[0002]

2. Description of the Related Art In a reaction tube used in the chemical industry such as a cracking tube, fins or uneven thickness portions are formed on the inner surface to enhance heat transfer to a fluid in the tube and to prevent ethylene or the like. Increasing yields are being done.

The cracking tube is generally manufactured by a centrifugal casting method. However, in this centrifugal casting method, it is not possible to form fins or uneven thickness portions on the inner surface of the tube when manufacturing the tube. Therefore, overlay welding is performed on the inner surface of the centrifugally cast pipe, for example, in a spiral shape.

However, overlay welding over the entire length of the inner surface of the pipe leads to high cost, and with a small diameter pipe, overlay welding on the inner surface of the pipe is impossible or extremely difficult. The present invention clarifies a method for efficiently manufacturing a nonuniform walled tube having a uniform outer diameter by pulling continuous casting.

[0005]

DISCLOSURE OF THE INVENTION The present invention is a mold hole that penetrates vertically.
The cooling mold (1) in which the outer circumference of the heat-resistant sleeve (2) having the (20) is surrounded by the cooling jacket (3) is exposed from the surface of the molten metal at the upper part and immersed in the molten metal at the lower part to form the mold cavity ( In the continuous pull-up casting method in which the molten metal is introduced into the inside of the pipe (20) and the molten metal solidified layer (61) which is in contact with the mold cavity (20) is pulled up to continuously cast the pipe (6), the sleeve (2) and the cooling jacket ( Use a cooling mold in which a portion having a high cooling capacity and a portion having a low cooling capacity are alternately present in the circumferential direction due to the formation of a hollow portion (22) locally with respect to (3) or the difference in thickness of the sleeve locally. By forming the portion of the cooling mold having a high cooling ability into a thick wall and the portion having a low cooling ability into a thin wall, an uneven thickness pipe having a uniform outer diameter is manufactured. The molten metal coagulation layer (61) may be pulled up while rotating.

[0006]

[Operation and effect] Since the cooling mold (1) has portions having high cooling ability and portions having low cooling ability alternately in the circumferential direction, a sleeve is used.
(2) The solidified solidified layer (61) solidified along the inner surface has a high solidified rate in a portion having a high cooling capacity and the solidified layer becomes thick. On the other hand, the solidification layer becomes thin in the portion having low cooling ability and the solidification layer becomes thin. The portion where the solidification rate is high and the solidified layer is thick becomes the thick portion of the pipe (6).

By continuously and straightly pulling up the molten metal coagulation layer (61), the thick wall portion and the thin wall portion can efficiently produce continuous thin walled pipes in the longitudinal direction of the pipe. Molten metal solidification layer
By rotating (61) and pulling it straight up,
The thick portion and the thin portion are each formed in a spiral shape.

[0008]

EXAMPLE FIG. 1 shows the state of implementation of continuous pull-up casting. The cooling mold for continuous casting (1) is a cylindrical sleeve.
Surrounding (2) with cooling jacket (3), cooling jacket
(3) is protected by a refractory layer (4).

The sleeve (2) is made of a heat-resistant material such as ceramic, graphite, or boron nitride, and has an inner surface serving as a die hole (20) vertically penetrating therethrough. The inner wall (31) of the cooling jacket (3), which is in contact with the outer surface of the sleeve (2), is made of copper having good thermal conductivity. The inside of the cooling jacket (3) is a water chamber (32) filled with cooling water.

The cooling mold (1) used in the practice of the present invention is
As shown in FIG. 2, the outer diameter of the sleeve (2) is carved from both sides of the diameter line to form parallel surfaces (21) (21), and the parallel surfaces (21)
A hollow part (22) is formed between the cooling jacket (3) and the inner wall (31) of the cooling jacket (3).

The hollow portion (22) serves as a heat insulating portion, and the sleeve
The cooling capacity is smaller than that of the portion where the outer surface of (2) is in contact with the inner wall (31) of the cooling jacket (3). That is, cooling mold (1)
Has a portion having a high cooling capacity and a portion having a low cooling capacity alternately in the circumferential direction.

FIG. 3 shows another embodiment of the cooling mold (1), and like the case of FIG. 2, the outer diameter of the sleeve (2) is carved from both sides of the diameter line, and the parallel surface (21 ) (21).
The inner wall (31) of the cooling jacket (3) is swollen at a portion corresponding to the parallel surface (21), and the entire outer surface of the sleeve (2) is in close contact with the inner wall of the cooling jacket (3).

The portion of the parallel surface (21) of the sleeve (2), that is, the thin portion, naturally has a higher cooling capacity than the other portions of the sleeve.
Therefore, also in the cooling mold (1) of FIG. 3, similarly to that of FIG. 2, a portion having a high cooling capacity and a portion having a low cooling capacity are alternately present in the circumferential direction.

Above the sleeve (2) of the cooling mold (1),
A pulling device (5) is provided. Example of lifting device (5)
Is constructed by disposing a pair of pinch rollers (51) (51) with the pulling transition path of the pipe (6) interposed therebetween.

Then, the cooling mold (1) is immersed in the molten metal (7) to such a depth that the molten metal surface reaches near the upper part of the sleeve (2). A starting rod (not shown) is inserted into the mold cavity (20) from above the cooling mold (1), waiting for solidification of the molten metal in the upper part of the mold cavity, and then the pulling device (5) pulls up the starting rod. The molten metal solidified layer (6
1) is pulled up together with the starting rod.

In the cooling mold (1), portions having high cooling ability and portions having low cooling ability are alternately present in the circumferential direction, so that the solidified and solidified layer (61) solidified along the inner surface of the sleeve (2) has the cooling ability. At a high portion, the solidification rate is fast and the solidified layer becomes thick. On the other hand, the solidification layer becomes thin in the portion having low cooling ability and the solidification layer becomes thin.

The portion where the solidification rate is high and the solidified layer is thick becomes the thick portion of the pipe (6). When the starting rod exceeds the pulling device (5), the pulling device (5) directly pulls up the casting pipe (6) in which the molten metal solidification layer (61) is hardened.

In this way, by continuously and straightly pulling up the molten metal solidification layer (61), the thick portion (6a) and the thin portion
In (6b), it is possible to efficiently manufacture the uneven thickness pipes that are continuous in the longitudinal direction of the pipes. Since the inner surface of the sleeve (2) is an arcuate surface, the pulling resistance of the molten metal solidified layer does not increase so much that the molten metal solidified layer is prevented from being suspended or cracked.

FIG. 4 shows a pulling device (5) capable of pulling up the pipe (6) while rotating it. A pair of drum-shaped pinch rollers (52) (52) are used to pull up the pipe (6). Some of them are arranged so as to be opposite to each other with the transition path sandwiched therebetween, and the pipe (6) and hence the molten metal coagulation layer (61) rotate the molten metal coagulation layer (61) by the rotation of the pinch rollers (52) (52). While being pulled straight, the thick-walled portion and the thin-walled portion are formed in a spiral shape. The present invention is not limited to the configuration of the above embodiment, and various modifications can be made within the scope of the claims.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a continuous casting state.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a sectional view of another embodiment of the above.

FIG. 4 is an explanatory view of another embodiment of the pulling device.

[Explanation of symbols]

 (1) Cooling mold (2) Sleeve (3) Cooling jacket (6) Pipe (61) Molten metal solidification layer

Claims (2)

[Claims] 1. A cooling mold (1) in which an outer periphery of a heat-resistant sleeve (2) having a vertically passing mold hole (20) is surrounded by a cooling jacket (3), and an upper part of the cooling mold is exposed from the molten metal surface. , The lower part is soaked in the molten metal, the molten metal is introduced into the mold cavity (20), the molten metal coagulation layer (61) that is solidified in contact with the mold cavity (20) is pulled up, and the pipe (6) is continuously cast. In the method, a hollow part (22) is locally formed between the sleeve (2) and the cooling jacket (3), or the thickness of the sleeve is locally different. By using a cooling mold in which parts and parts are alternately present, a part with high cooling capacity of the cooling mold is made thick and a part with low cooling capacity is made thin to manufacture an uneven thickness pipe with a uniform outer diameter. how to. 2. The method for producing an uneven wall thickness tube according to claim 1, wherein when the molten metal coagulation layer (61) is pulled up, the molten metal solidified layer is pulled up while being rotated to form a thick wall portion in a spiral shape.