JPH06142849A - Pull up continuous casting - Google Patents

Abstract

PURPOSE:To stably pull up in the long cycle of holding of the pull up of a molten metal solidified layer by forming a well solid molten metal solidified layer on a surface of a mold hole during holding period and returning a lower edge of the pull up to the original as the solidified layer, which is of a part lower than the solid layer, is pulled up at the next pull up. CONSTITUTION:A cooling mold 1 having an up and down piercing through mold hole 21 is placed in the bath accommodating a molten metal with exposing its upper part from a molten metal surface and immersing its lower part in a molten metal, the molten metal coming to contact with the mold hole 21 is cooled and solidified, intermittently pulling up a molten metal solidified layer 61 and continuously producing a pipe. And, in the course of a short cycle pull up pattern, which pulls up the molten metal solidified layer 61 in short cycle and intermittently, a holding time (t), which is well longer than the holding time for a short cycle pull up pattern, is provided long cycle wise, the holding time (t) accelerates the solidification of molten metal, as a result, correcting a lower edge position of the molten metal solidified layer 61 toward lower.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pulling continuous casting method.

[0002]

2. Description of the Related Art A conventional pulling continuous casting method is, as shown in FIG. 1, a cooling mold (1) having a die hole (21) penetrating vertically.
The upper part is exposed from the surface of the molten metal, and the lower part is immersed in the molten metal so that the molten metal enters the mold cavity (21).

A pulling device provided above the cooling mold (1)
A starting rod (not shown) is clamped in (5), and the lower end of the rod is immersed in the molten metal surface in the mold cavity (21) of the cooling mold (1).

The cooling water in the cooling jacket (3) surrounding the die cavity (21) solidifies the molten metal in contact with the molten metal surface in the die cavity (21) and the die cavity (21), and the pulling device (5) ), The starting rod, and hence the molten metal solidification layer (61), is pulled up intermittently to continuously cast the pipe.

[0005]

As shown in FIG. 3, stable continuous casting is possible if the lower end (61b) position of the pulled molten metal solidification layer (61a) does not change at each pulling cycle (sleeve and molten metal Although only the cross section of the left side portion of the solidified layer is shown), the position of the lower end (61a) of the molten metal solidified layer thus pulled up is not necessarily constant. When the lower end position of the molten metal solidified layer changes upward in a certain cycle than in the previous cycle, it tends to change further in the next cycle.

FIG. 4 shows changes in the lower end position of the molten metal solidified layer with time from left to right. FIG. 4A shows the lower end position of the molten metal coagulation layer before being pulled up (only the left cross section of the sleeve and the molten metal coagulation layer is shown). Figure 4 (b)
Indicates a state in which the molten metal solidified layer has grown during the stop time in intermittent pulling. In Fig. 4 (c), the solidified layer (61a) grown in (b) is pulled up by 6mm from the state of (b), and 2m from the lower end.
It shows the state of rising at break at m.
FIG. 4D shows a state in which the molten metal solidified layer has grown at the next stop time. Figure 4 (e) is 6mm pulled up from the state of (d), (d)
The state where the solidified layer (61a) grown in (2) is broken at 2 mm from the lower end, that is, the state is broken at 4 mm from the lower end position in (b) is shown. By repeating the above, the lower end position of the pulled molten metal solidified layer is displaced upward by 2 mm each time the pulling is performed, and finally the pulled lower end position reaches the molten metal surface and breaks out, and continuous casting is interrupted. The present invention clarifies a pull-up continuous casting method that can solve the above-mentioned problems by adjusting the lower end position of the molten metal solidified layer downward at a constant cycle.

[0007]

The pulling continuous casting method of the present invention is
A cooling mold (1) having a mold hole (21) penetrating up and down is placed in a tank containing the molten metal, the upper part of which is exposed from the surface of the molten metal, and the lower part of which is immersed in the molten metal, and is contacted with the mold hole (21). In the continuous casting method of pulling, in which the molten metal solidified layer (61) is intermittently pulled up while cooling and solidifying the molten metal to produce pipes continuously, the molten metal solidified layer (61) is pulled up intermittently at short intervals. In the middle of the cyclic pull-up pattern, a stop time t sufficiently longer than each intermittent stop time in the short-cycle pull-up pattern is provided for a long period, and the stop time t promotes solidification of the molten metal, resulting in a molten metal coagulation layer. It is characterized in that the lower end position of (61) is adjusted downward.

[0008]

[Operation and effect] During a long stop time t, a sufficiently solidified solidified layer (61) is formed on the surface of the mold cavity (21), and the solidified layer below the solidified layer is pulled up by the next pulling up. The lower end is adjusted to the original position. As described above, the repeated pattern of pulling up the molten metal solidified layer a predetermined number of times and then stopping the pulling up for a predetermined time prevents breakout and enables stable continuous casting.

[0009]

EXAMPLE FIG. 1 shows a pulling continuous casting apparatus used in the present invention, wherein the cooling mold (1) is a cylindrical liner (2).
Is surrounded by an annular cooling jacket (3), and the outer periphery and bottom of the jacket are protected by a refractory layer (4). A water chamber (31) filled with cooling water is formed inside the cooling jacket (3).

A pulling device (5) such as pinch rollers (51) (51) for pulling up the molten metal solidification layer (61) is provided above the cooling mold (1), and the pulling device (5) is a control device. By (not shown), the pulling frequency per unit time, the pulling amount, and the pulling stop time per unit time can be arbitrarily set.

However, the cooling mold (1) is exposed at the upper surface from the molten metal surface, and the lower portion is immersed in the molten metal so that the molten metal is placed in the liner (2).
Infiltrate (6).

The starting rod is held between the pinch rollers (51) (51), and the lower end of the rod is inserted into the mold cavity of the cooling mold (1).
(21) Soak in the hot water inside.

After the molten metal in contact with the molten metal surface in the mold cavity (21) and the mold cavity (21) is solidified, the pulling device (5) intermittently discontinues the starting rod, that is, the molten metal coagulation layer (61). Raise.

FIG. 2 shows the molten metal coagulation layer (61) with respect to the number of pulling times per unit time n and the long cycle stop time t per unit time.
It is a linear representation of the relationship of the vertical change of the lower end position of. It can be seen that the lower end position of the molten metal coagulation layer rises when the number of times of pulling in the unit time increases, and the lower end position of the molten metal coagulation layer lowers when the pulling is stopped next.

After stopping for t seconds, the intermittent pulling is restarted,
Continuous casting is performed by repeating the stop for t seconds and the intermittent pulling operation. The bottom end of the molten metal coagulation layer (61) can be prevented from breaking out only by moving up and down within a substantially constant range.

In the embodiment, when the intermittent pulling pitch is 6 mm and the intermittent pulling number n is 30 times, the rising height of the lower end of the molten metal coagulating layer is 40 mm. It has been found that it is possible to set the stop time t to 5 seconds. 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 a cross-sectional view of a pulling continuous casting device.

FIG. 2 is a diagram showing a relationship between a pulling pattern and a change in a lower end position of a molten metal solidified layer.

FIG. 3 is an explanatory view in which a molten metal solidified layer moves up and down within a certain range.

FIG. 4 is an explanatory diagram in which a molten metal solidified layer reaches a breakout.

[Explanation of symbols]

 (1) Cooling mold (2) Liner (3) Cooling jacket (4) Refractory layer (5) Pulling device

Claims (1)

[Claims] A cooling mold (1) having a mold hole (21) penetrating vertically is provided in a tank containing the molten metal by arranging it so that the upper part is exposed from the molten metal surface and the lower part is immersed in the molten metal. (21) in the pulling continuous casting method for continuously producing a pipe by intermittently pulling up the molten metal solidified layer (61) while cooling and solidifying the molten metal,
In the middle of the short cycle pulling pattern for intermittently pulling up the molten metal solidified layer (61) in a short cycle, a long stop time t sufficiently longer than each intermittent stop time in the short cycle pulling pattern is provided for a long period, and the stop is performed. Promotes solidification of the melt by time t,
As a result, the pulling continuous casting method is characterized in that the lower end position of the molten metal solidification layer (61) is adjusted downward.