JPS63160748A - Continuous casting method for hollow bloom - Google Patents

Abstract

PURPOSE:To execute continuous casting with prevention of bulging by inserting an inner wall mold having multiple pipe construction into a mold, water-cooling the mold through a gap at outer circumferential side of the multiple pipes and supplying the spray water in the internal pipe part to cool the inner face of hollow bloom. CONSTITUTION:The inner wall mold 2 having multiple pipe construction is inserted in the mold 1 and in the outer circumferential gap part 3, the cooling water flowing to the drainage hole 6 from a supplying hole 5 through a partition plate 4, is passed through to cool the mold 2. And, in the inner pipe part of mold 2, a spray piping 8 communicating to a main pipe 7 is inserted and the inner face of hollow bloom is cooled by plural spraying nozzles 9 at the tip part of piping 8. Thus, the molten metal is cooled from both faces of the mold 1 and the inner wall mold 2, to form the solidified shells 14a, 14b at each face. Further, the steam generated from the spraying water is exhausted from draft hole 12 of a dummy bar 10 and exhaust duct 13 of the mold 2. In this way, the continuous casting with prevention of bulging is executed.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a method for continuous casting of hollow plumes.

Conventional technology Generally, seamless pipes are made by heating a square or round plume at high temperature and rolling it, inserting a plug in the longitudinal direction of the plume to punch a hole, and then sequentially rolling the pipe. However, there are problems such as complexity and high production cost.

Therefore, for example, as in Japanese Patent Application Laid-open No. 126945, a free-cutting steel pipe is used as a core, this is poured simultaneously with molten steel, continuous casting is carried out in a casting method, and then the core is turned and removed. , a method has been proposed to remove the core in a short time and cast a hollow round plume.

However, this method requires a consumable core.

The manufacturing process is also complicated, and there are also restrictions on the length of the hollow plume material that can be manufactured.

In addition, since the core is free-cutting steel, it needs to be thick enough to ensure heat capacity to prevent it from melting in the mold, and the remaining wall thickness must be strong enough to prevent deformation or breakage due to the static pressure of the molten steel. must be maintained.

As a result, the basic unit of the core becomes large, leading to high costs.
It has drawbacks that make it difficult to put it into practical use.

As a method to solve these drawbacks, for example,
As in Japanese Patent No. 1-48225, a casting method has been proposed in which a cylindrical inner wall mold is inserted into the mold and rotated, and the inner surface of the hollow plume to be manufactured is pressed with a plurality of Tyco type rolls.

The method described above has resulted in considerable improvements such as eliminating the need for expensive cores and cutting and removing the cores after Y# manufacturing.

However, this method also involves rotating the cylindrical inner wall mold. The cost is high because it requires a mold for the inner wall with a complicated mechanism equipped with tie rolls etc. that press the inside of the hollow plume.Also, it is necessary to solidify the inner surface of the hollow plume while pressing the slab with tie rolls. , does internal bulging occur?

Otherwise, serious situations such as breakout due to damage to the solidified shell due to reheating, uneven solidification, etc. may occur.Furthermore, high-speed casting becomes impossible because the inner surface of the hollow plume cannot be sufficiently solidified. It has drawbacks such as a decrease in productivity.

Problems to be Solved by the Invention The present invention solves the drawbacks of the conventional hollow plume casting method as described above, casts a predetermined hollow plume in a simple and inexpensive manner, and promotes solidification of the inner surface. The object of the present invention is to provide an I-adic method for hollow plumes that sufficiently suppresses 11S problems such as bulging or breakout, and enables high-speed casting.

Means for Solving the Problems The continuous casting method for hollow plumes according to the present invention will be described below.

The present inventors have obtained the following knowledge as a result of conducting various studies when casting a hollow plume.

First of all, the feasibility of casting a hollow plume is determined by the fact that it is necessary to secure a certain amount of solidification on the inner surface of the hollow casting, and it is also necessary to suppress heat recovery in the surrounding space. By controlling the solidification thickness and recuperation, it is possible to perform casting that prevents bulging without supporting with rolls or the like.

Based on these findings, the present invention applies to the casting of a hollow plume, and an inner wall mold made of multiple cylindrical tubes is inserted into the mold. The purpose is to cool the inner surface of the hollow plume by water cooling through the outer peripheral gap of this cylindrical inner wall mold (hereinafter simply referred to as inner wall mold) and by flooding the inner tube of the multi-pipe with spray water.

The method for casting a hollow plume according to the present invention will be described in detail below based on examples.

FIG. 1 shows a cross-sectional view at the start of casting in an embodiment of the hollow plume casting method according to the present invention, and FIG. 2 shows a cross-sectional view of FIG. 1 during casting.

First, as shown in Fig. 1, inside the mold l is an inner wall mold 2.
It's decorated. This inner wall mold 2 is formed of multiple pipes, and a water supply port 5 is provided in the outer circumferential gap 3 via a partition plate 4, for example.
Cooling water is supplied from the drain port 6 and drained from the drain port 6 to remove heat and cool the surface of the inner wall mold 2 that comes into contact with the molten metal.

In addition, a spray pipe 8 communicating with the spray water main pipe 7 is installed in the inner pipe part, and the tip of the spray pipe 8 appropriately projects beyond the length of the inner wall mold 2, and the projecting part has a plurality of A spray nozzle 9 is provided to cool the inner surface of the plume hollowed out by the inner wall mold 2.

In the initial stage of casting, this inner wall mold 2 has a heat-resistant sealing material 11 such as asbestos in the dummy par 10 at the lower end.
The above-mentioned spray nozzle 9
A vent hole 12 is provided in the dummy par 10 for discharging spray water supplied after the start of casting or water vapor generated by heat removal. The steam generated by this spray water is also carried out through a steam exhaust duct 13 provided within the inner wall mold 2.

This is because if the steam generated by water cooling the inner surface of the hollow plume is not quickly removed, the inner pressure may induce bulging or breakout of the outer surface of the hollow plume.

The molten metal to be produced is poured into the mold l through an immersion nozzle (not shown), and is cooled from the outside and inside by the mold l and the inner wall mold 2, forming solidified shells 14a and +, respectively.
Form 4b.

Next, the dummy par 10 is pulled out at low speed and solidified by the inner wall mold 2! When the 9IiIiIR14b reaches the spray nozzle 9, cooling water is ejected from the spray nozzle 9 to accelerate the solidification rate of the hollow surface.

Since a large amount of water vapor is generated within the plume hollow, an exhaust duct 13 for discharging the vapor is provided at the inlet of the spray pipe 8 at the head of the inner wall mold 2. Or conversely, inner wall mold 2
By blowing high-pressure air from the head of the plume and performing air-water cooling that also serves as a purge toward the tip of the plume through the hollow part of the plume, it is preferable because the cooling ability of the slab can be improved and made uniform.

A portion of the spray water that cooled the plume hollow surface turns into steam and is discharged by the method described above, but most of the water flows down inside the plume hollow, and during the extraction of dummy A-IQ, it is installed at the head of dummy bar IO. During normal extraction, the plume is discharged from the tip of the plume.

After sequential casting is performed in this manner and the dummy bar 10 is separated, a portion of the spray water flows down inside the hollow plume and is drained out of the system.

In addition, seizure may occur between the inner wall mold 2 and the slab, which may cause breakage (7A), so to prevent seizure, the mold 1 and the inner wall mold 2 are
Either connect it to the vibration source and apply the same cycle of vibration, or
Alternatively, an ultrasonic vibrator (not shown) may be attached to the inner wall mold 2 to vibrate it.

Example Table 1 shows a comparison of the case where a 315φ hollow plume was cast by applying the above-mentioned method to a low carbon pipe material and the case where a solid plume was cast using the conventional method.It is clear that high-speed casting is possible. It can be seen that the cost of casting pipes can be greatly reduced, and troubles such as bulging and breakouts can be eliminated.

(Margin below) Table-1 *1 indicates the difference when compared to other hollow casting methods.

Effects of the Invention As described above, by using the hollow plume casting method according to the present invention, the hollow surface of the hollow plume can also be spray cooled, so it is possible to form a solidified shell that dissolves in the static pressure of molten steel at the same speed on both the inner and outer surfaces. Therefore, there is no need to reduce the drawing speed, and high productivity can be maintained.

Further, since thermal stress can be eliminated by cooling the inside and outside under similar conditions, defects inside the surface can be suppressed and this can be done easily and inexpensively.

[Brief explanation of the drawing]

FIG. 1 shows a cross-sectional view before the start of casting in one embodiment of the hollow plume casting method according to the present invention, and FIG. 2 shows a cross-sectional view during casting of FIG. 1. l... Mold, 2... Inner wall mold, 5... Water supply port, 6... Drain port, 8... Spray piping, 9... Spray nozzle, 10... Dummy/<+, 13... Exhaust duct.

Claims (1)

[Claims] In a continuous casting method in which a hollow plume is cast by inserting a cylindrical inner wall mold into a mold, the cylindrical inner wall mold is made of multiple tubes, and cooling water is supplied to the outer peripheral gap of the multiple tubes to form the cylindrical inner wall mold. A method for continuous casting of a hollow plume, characterized in that the hollow inside of the slab is spray-cooled through a spray nozzle provided at the tip of the inner tube of the multiple tube.