JPH0323041A - Method for controlling cooling in belt type continuous casting machine - Google Patents

Abstract

PURPOSE:To eliminate leakage of cooling medium at the time of starting and the detachment of coating on surface of a mold by rising the liquid pressure of the cooling medium film according to descent of a dummy bar and tip part of a casting starting part in the mold. CONSTITUTION:Pouring of molten metal into the belt mold from a tundish 11 starts, and after the starting part solidifies, the starting part or the dummy bar part advances while synchronizing with advancing of the belt 1 from a1 to a3. This advancing position is measured with a counter 13 for cast slab. Before the end part of starting part or the dummy bar part passes through each section, the cooling water is allowed to flow in the min. flow rate so as not to bring the belt 1 into contact with each cooling pad 3. At the time, when the end part of starting part or the dummy bar part passes through each section a1, a2, a3 in order, operation of a flow rate control valve 9 is executed so as to apply pressure corresponding with molten metal static pressure to the section corresponding with the above. By this method, good casting condition can be maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a cooling control method in a belt-type continuous casting machine used to continuously cast thin slabs.

In belt-type continuous casting machines, the belt mold is usually heated with a cooling medium (usually water) on the side opposite to the side that contacts the molten metal or slab.
During this process, the belt mold is supported by the liquid pressure of the cooling medium film which balances the static pressure of the molten metal.

At the start of casting, a molten metal pool is usually created near the pouring part using a dummy bar, etc., and after the slab hardens in the molten metal pool, drawing is started, resulting in continuous casting.

For dummy bars, in order to simplify and speed up the casting preparation work, a short dummy bar as shown in Japanese Patent Application Laid-Open No. 59-1189046, and a method of omitting the dummy bar as shown in Japanese Patent Application Laid-Open No. 59-195555 have been proposed. There is.

However, when casting is started using method 1, the belt mold located behind the sump containing or not containing the dummy bar in the casting direction is not subjected to static pressure of the molten metal, and is therefore pushed by the pressure of the cooling medium. This increases the gap between the belt mold and the cooling pad, causing the cooling medium to overflow from the sides of the belt mold. At this time, if the water used as a cooling medium overflows from the sides of the belt and wraps around the surface of the belt mold, the water may cause a steam explosion when that part enters the casting space. As a result, brushing may occur, causing pitting defects on the surface of the slab, which is also dangerous.

Sealing the end of the belt is disclosed in Japanese Patent Application Laid-Open No. 61-4965.
Although it is proposed in Japanese Patent No. 9, it is actually difficult to seal the gap between the belt and the pad in an open state, and the following disadvantages cannot be overcome.

In other words, the second disadvantage of placing the belt in the thickness direction of the slab is that the belts rub against each other, which makes it difficult to maintain the casting conditions as shown in Japanese Patent Application Laid-Open No. 59-220255. The coating material will peel off.

(Problem to be Solved by the Invention) Cooling control that can appropriately avoid the above-mentioned operational troubles caused by the hydraulic pressure of the cooling medium film acting on the belt mold when starting casting operations using a belt-type continuous casting machine. It is an object of this invention to provide a method.

(Means for Solving the Problems) This invention is directed to the operation of a belt-type continuous casting machine in which a belt mold is supported by a coolant film with a hydraulic pressure that balances the static pressure of the molten metal acting on the belt mold. As the dummy par and/or the tip of the casting start part descends within the belt mold at the start of the process,
A cooling control method for a belt-type continuous casting machine, characterized in that the liquid pressure of the cooling medium film is increased.

In general, water is often used as a cooling medium for belt-type connected casting machines, so examples using cooling water will be described below.

FIG. 1 shows a belt type continuous casting machine to which the method of the present invention is applied. In the figure, 1 is a belt, 2 is a guide roller, 9 is a flow control valve, 10 is a flow meter, 11 is a tundish, and 13 is a slab counter.

In this continuous casting machine, as shown in FIG. 2, the belt is cooled by a film of cooling water that is ejected from a cooling pad 3 on the back of the belt and returns into the cooling pad 3.

As shown in detail in FIGS. 3(a) and 3(b), this water film cooling consists of a row of water inlets 3a lined up in the width direction of the slab 4, and holes 3b of drain ports located a certain distance from the row of water inlets 3a. are provided alternately, and a cooling water film 6 is formed between the belt and the cooling pad by causing the cooling water flowing out from the water supply port 3a to flow into the drain port 3b. This cooling water film 6 is designed to balance the static pressure of the molten metal during steady casting.

(Function) As shown in Fig. 1, pouring of metal from the tundish 11 into the belt mold begins, and after the start part solidifies, the start part or part of the dummy bar moves from the illustrated section al-a2 to a3. Proceeds in synchronization with the progress of Bell}1.

This advancing position is measured with the slab counter 13, and until the start end or a part of the dummy bar passes through each section, the lowest flow rate of cooling water that does not allow the belt 1 to touch the cooling pad 3 is allowed to flow. When the start end or dummy bar passes through each section al+a2+a3 in sequence, the flow rate control valve 9 is operated so that a pressure matching the static pressure of the molten metal is applied to the corresponding section.

Figure 4 illustrates the procedure for adjusting the water film pressure.

In addition, as shown in FIG. 5, when using the dummy par 14, an elastic body 15 such as rubber is inserted between the dummy par 14 and the belt mold 1.
It is advisable to intervene.

(Example) Low carbon aluminum killed steel was continuously cast into a slab size of 30 mm thick x 1000 mm wide by the method shown in FIG.

Figure 4 shows the change in water film pressure over time in sections a2 and a3 at the start of casting. The passage of the slab starting portion through each portion was detected by the slab counter 13, and the water film pressure was increased.

(Effects of the Invention) The method of the present invention eliminates the leakage of the cooling medium from the side surface of the belt mold at the start of casting and the peeling of the surface coating of the belt mold, making it possible to maintain good casting conditions.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing a belt type continuous casting machine to which the method of the present invention is applied, Fig. 2 is a sectional view of the belt type continuous casting machine, and Fig. 3 is a water film cooling device of the belt type slave casting machine. A front view and a side view, FIG. 4 is a graph showing the behavior of water film pressure over time at the start of casting, and FIG. 5 is a cross-sectional view of a short dummy bar containing an elastic body. 1...Belt 2...Guide roller 3
... Cooling pad 4 ... Slab 5 ... Pinch roller 6 ... Cooling water film 7 ... Water supply header
8... Drain header - 9... Flow rate adjustment valve
10... Flow meter l1... Tandi Sosh 12.
...Short side mold l3...Slab counter 14...
Dummy bar 15...Elastic body Figure 3 Figure 4 Hajime Haruma

Claims (1)

[Claims] 1. In operation of a belt-type continuous casting machine in which the belt mold is supported by a cooling medium film with a hydraulic pressure that balances the static pressure of the molten metal acting on the belt mold, at the start of pouring the metal discharged from the tundish. A cooling control method for a belt-type continuous casting machine, characterized in that the liquid pressure of the cooling medium film is increased as the tip of a dummy bar and/or a casting start part descends within a belt mold.