JPH0428463B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for continuously casting thin steel slabs using a twin-belt horizontal continuous casting machine (hereinafter referred to as a twin-belt horizontal continuous casting machine). This relates to a rope water heater.

Conventionally, thin sheet materials of ferrous metals are first cast into slabs with a thickness of 200 to 300 mm using the normal rigid continuous casting method as shown in Figure 1, and then hot-rolled and cold-rolled. It was common for the product to be manufactured through a multi-step process of processing it and making it into plates.

However, in recent years, advances in steelmaking technology and casting technology have made it possible to manufacture slabs with good properties, and against the backdrop of various circumstances such as the spread of labor-saving and energy-saving ideas, hot rolling has been adopted. There is a growing momentum to manufacture thin sheets of ferrous metals without having to do so. However, if we attempt to directly manufacture thin sheets from slabs by cold rolling alone, it is necessary to manufacture wide thin slabs with a wall thickness of approximately 40 mm or less at a high speed, and the surface It has been almost impossible to meet these demands with the conventional continuous casting process, as shown in FIG.

On the other hand, a twin-belt horizontal continuous casting machine as shown in Figure 2 has been put into practical use for casting non-ferrous metal sheets such as copper, zinc, and aluminum once cooled, and can produce thin sheets from molten metal extremely efficiently. Since then, a large number of devices are currently in operation in various countries.

What is shown in Fig. 2 is a schematic representation of the casting state of an extremely common twin belt caster used for casting non-ferrous metal sheets, and the rotation of the upper and lower pulleys 8 and 8' is shown in Figure 2. When the molten metal 2 is injected from the gutter 11 attached to the tundish 10 between the endless belts 9 and 9' which are moving by Since they are moved in the same direction and cooled and solidified, the solidified slabs 7 can be taken out continuously and easily at high speed. Note that the reference numeral 12 is an edge dam that constitutes the mold wall together with the endless belts 9 and 9'.

Therefore, many attempts have been made to apply this twin-belt horizontal continuous casting machine to casting thin slabs of ferrous metals, but ferrous metals have extremely high melting points compared to general nonferrous metals. Various problems arise due to differences in smelting methods, etc., and the current situation is that it has not yet been put into practical use.

In view of the above-mentioned viewpoint, the inventors of the present invention particularly aimed to produce extremely thin slabs from molten steel with high efficiency, and in particular, to manufacture ultra-thin slabs possessed by the twin-belt horizontal continuous casting machine. Focusing on the high-speed casting characteristics of In the process of repeatedly considering and researching various aspects to make steel manufacturing possible, when casting steel slabs on an actual operational scale using a twin-belt horizontal continuous caster, the continuous caster Conventional continuous casting (normal vertical continuous casting,
If we were to adopt the hot water supply system used for continuous casting (also known as twin-belt horizontal continuous casting machines for non-ferrous metals), there would be a serious problem in that it would be impossible to continue good casting work in a stable manner. I found out what to do.

First of all, as shown in Fig. 1, the hot water supply device of a conventional continuous caster for steel slabs has a ladle
The ladle 2 and the tundish 4 are configured to receive the molten steel 2 from the tundish 4 and then inject it into the mold 6.
The role of is as follows. That is, A. Ladle (a) Transports molten steel to be refined in batches to continuous casting equipment.

(b) The bottom nozzle is equipped with a stopper rod or sliding nozzle 3, which continues to supply molten steel to the tundish 4 at an appropriate flow rate during casting work.

B Tundish (a) The bottom nozzle is equipped with either a stopper rod or a sliding nozzle 5, or both, and continues to supply molten metal to the mold 6 at an appropriate flow rate.

(b) Provide a certain amount of capacity and use the residence time of molten steel to separate inclusions.

(c) By designing the capacity sufficiently, mold 6 can be replaced even when changing ladle 1 in continuous casting.
Continue to maintain hot water supply.

(d) In a multi-strand continuous caster, molten steel from the ladle 1 is distributed to a plurality of molds 6, and the amount of hot water supplied from time to time is controlled for each strand.

However, in the twin belt horizontal continuous casting machine, as is clear from Figure 2, it is necessary to supply hot water with a width spread between the two belts 9 and 9', which are slightly inclined than the sailor. Therefore, it was impossible to apply the tundish used in a conventional steel slab continuous casting machine as shown in FIG. 1 to this machine. Therefore, when pouring into a twin-belt horizontal continuous casting machine, a tundish equipped with a gutter 11 or a nozzle, as shown by reference numeral 10 in FIG. 2, is used, and the molten metal 2 is poured out from the gutter or nozzle. It is essential to obtain a good injection flow, and the tundish for injecting molten metal into a twin-belt horizontal continuous casting machine naturally refers to the tundish described above. In such a tundish, it is necessary to control the amount of molten metal inflow even more strictly in order to obtain a good injection flow.

Therefore, as a water heater for a twin-belt horizontal continuous caster for non-ferrous metals that uses this type of tundish, the one shown in FIG. 3 is typically employed.

To obtain molten nonferrous metal, a continuous melting furnace is usually used, and therefore the water supply apparatus shown in FIG. 3 also includes a continuous melting furnace 13, a holding furnace 14, a tundish 10, and a gutter 15 connecting these , and is equipped with some kind of flow control means between the holding furnace 14 and the tundish. In the example of FIG. 3, this corresponds to the flow rate control plug 16 on the outlet side of the holding furnace and the float type flow rate control nozzle 17 downstream thereof.

The molten metal obtained in the continuous melting furnace 13 is sent to the tundish 10 with a controlled flow rate without requiring a ladle, and is formed into a good injection flow from the pouring port of the tundish. It is injected into the casting machine 18.

However, the configuration of such a water heater is completely unsuitable for a twin-belt horizontal continuous caster for steel slabs, as described above. because,
The current mainstream method for steel is batch refining in converters, electric furnaces, etc., and it is essential to first receive the molten steel in a ladle, and steel has a lower melting temperature than non-ferrous metals. This is because the temperature of the molten metal tends to drop due to the high temperature, and there are problems such as it is not a good idea to transport the molten metal using long troughs.

Therefore, considering the above, when applying a twin-belt horizontal continuous casting machine to the continuous casting of steel slabs, the hot water supply system should be replaced with a normal vertical mold type as shown in Figure 1. Based on the combination of ladle and tundish in a continuous casting machine, the conclusion was drawn that the tundish should be adapted to the unique shape of the twin-belt horizontal continuous casting machine, and the outline is shown in Figure 4. As shown in the figure, this model is equipped with a so-called twin-belt horizontal continuous caster molten metal supply tundish, which has a shape that spreads from the tip in the width direction and supplies molten steel, and injects molten steel from the ladle from behind. A water heater comes to mind, but as a result of various experiments, it has been found that a water heater configured in this manner has the following problems. That is, since molten steel is supplied through a ladle from the upper part of a relatively narrow tundish, when changing the ladle during continuous casting, the supply of hot water to the twin-belt horizontal continuous caster is interrupted, making continuous casting operations impossible. thing.

Since the amount of hot water supplied to the twin-belt horizontal continuous caster is controlled by the ladle sliding nozzle 3, in the case of a multi-strand continuous caster, it is not possible to control the amount of hot water supplied moment by moment for each strand. .

In other words, as is clear from FIG. 5, even if we try to individually control the amount of molten steel flowing from the tundish 10 to the multiple twin-belt horizontal continuous casters 18, 18, it is impossible to do anything with only the ladle sliding nozzle 3. Instead, it becomes necessary to develop a new special device to control the flow of molten metal at the inlet. In addition, the reference numeral 1 in Fig. 5
The one indicated by 9 is a pinch roll.

In the hot water supply system shown in FIG. 4, the ladle sliding nozzle 3 must be used to control the amount of hot water supplied moment by moment. In order to achieve this, it is necessary to minimize the surface area of the molten steel in the tundish to make the degree of rise and fall of the molten steel surface as sharp as possible. In order to prevent inclusions from being brought into the casting machine, it is necessary to increase the capacity of the tundish and to float and separate the inclusions within the tundish, which is extremely difficult to adjust.

In other words, in the two-stage hot water supply system as shown in Figure 4,
Although it is desirable for the tundish to be as small as possible from the viewpoint of hot water supply controllability, it is desirable for the tundish to be as large as possible from the viewpoint of slab quality.

If the tundish is not sufficiently preheated, the temperature at which the molten steel is poured into the belt caster will drop, and abnormal phenomena such as skinning of molten steel will occur on the trough of the tundish, resulting in disturbance of the injection flow.
Generally, it is necessary to preheat the tandate until just before the start of casting, as this may lead to quality deterioration or operational failure. It is necessary to preheat the tandaishi with a gas burner.

This invention was made in order to solve the various problems mentioned above, and its characteristics are as follows: It consists of a parent tundish for receiving the molten steel, and a child tundish for receiving the molten steel supplied from the parent tundish and injecting it into the twin belt horizontal continuous casting machine, and the parent tundish and the child tundish are independent. The structure is such that the caster is supported by separate parent and child tundish cars and can independently move back and forth in parallel to the casting direction of the twin-belt horizontal continuous caster.

FIG. 6 is a schematic diagram showing the outline of the water supply device of the twin-belt horizontal continuous caster for steel slabs of the present invention, in which molten steel 2 is supplied to the twin-belt horizontal continuous caster 18 that casts the steel slab 7. A hot water supply device for the purpose of It is constructed with a secondary tundish 22 for receiving molten steel supplied at a controlled flow rate and injecting it into a twin-belt horizontal continuous casting machine. The functions and features of the ladle, parent tundish, and child tundish in this case are as follows. That is, A. Ladle (a) Transports molten steel to be refined in batches to continuous casting equipment.

(b) The bottom nozzle is equipped with a stopper rod or a sliding nozzle 3, which continues to supply molten steel to the parent tundish 20 at an appropriate flow rate during casting operations.

B Main tundish (a) The bottom nozzle is equipped with either a stopper rod or a slide-in nozzle 21, or both, which controls the amount of hot water supplied to the twin-belt horizontal continuous caster 18 by adjusting the outflow amount. .

(b) It has a certain capacity and uses the residence time of molten steel to float and separate inclusions in the tundish. In this case, the child tundish 22 is not expected to have the function of floating and separating the inclusions.

(c) by adequately designing its capacity;
Hot water supply to the secondary tundish 22 can be maintained even during ladle replacement work in continuous casting.

(d) In a multi-strand continuous casting machine, as shown in Fig. 7, the molten steel 2 from the ladle 1 is transferred to the secondary tundish 2 provided for each strand.
The amount of hot water supplied to each strand can be easily controlled by the main tundish sliding nozzles 21, 21, etc.

C Sub-tandake A gutter tip suitable for the inlet shape of the twin-belt horizontal continuous casting machine is provided at its front end, and the molten steel is supplied to the twin-belt horizontal continuous casting machine 18 with a predetermined spread. Therefore, it is desirable that the capacity of the secondary tundish 22 be as small as possible in order to better control the amount of hot water supplied to the twin-belt horizontal continuous casting machine.

Therefore, by using a three-stage hot water supply system as in the present invention, even if molten steel is refined in batches and is transported in predetermined amounts by ladle each time, it is possible to It is possible to continue casting work without interrupting the hot water supply to the twin belt horizontal continuous caster when changing the pot, and it is also possible to finely and delicately adjust the amount of hot water supplied to the twin belt continuous caster. Even in the case of multi-strand casting, the amount of hot water supplied can be precisely controlled for each strand.

FIG. 8 shows an embodiment of the steel slab melting twin-belt horizontal continuous caster water heater of the present invention. In this embodiment, in order to ensure the floating of inclusions in the molten steel received from the ladle 1, the water heater has a capacity that can accommodate the amount of hot water supplied for 5 minutes per hour (specifically, 2.4 tons/hour). For the amount of molten steel supplied in
12 ton capacity) and a parent container 20 with a capacity of 12 tons.
In order to ensure hot water supply controllability, the main element was designed to be as compact as possible to the extent that the refractory lining was not significantly attacked by the parent tundish injection flow, and the secondary tundish 22 was designed to have a molten steel capacity of 1.5 tons. In FIG. 8, the ladle 1 is supported on a ladle stand 23, and the molten steel from the ladle flows into the parent tundish 20 under the control of the sliding nozzle 3.

The injection flow from the ladle 1 into the parent tundish 20 is protected from oxidation by the atmosphere by the seal 24. In addition, the main tray 20 has a lifting mechanism 2.
5, and is able to run parallel to the slab drawing direction between a preheating position and a predetermined casting position. The molten steel from the parent tundish 20 is sent to the sliding nozzle 21.
and extension tube 2 for preventing oxidation of molten steel
After passing through 7, the child is led to the child 22.

The secondary tundish 22 is equipped with a stopper nozzle 28 for removing residual steel and a skinmer 29, and is loaded on the secondary tundish car 30, and also moves between the preheating position and a predetermined position during casting in parallel to the slab drawing direction. It is said to be driveable. Molten steel is introduced into the twin-belt horizontal continuous caster 18 from the tip of the gutter tip of the secondary tundish 22. In FIG. 8, the reference numeral 31 indicates a parent tertiary car running rail, and the numeral 32 indicates a child ternary car running rail.

After the main tundish 20 and the child tundish 22 are preheated by a burner (not shown) at a location away from the twin-belt continuous caster 18, the main tundish 20 is heated by a parent tundish car 26, and the child tundish 22 is turned into a sub tundish. They are each transported close to the twin-belt horizontal continuous casting machine 18 by the dateshield car 30 and set therein. After setting the main tundish 20 and child tundish 22, the molten metal 2
The ladle 1 containing the ladle is finally set as shown in FIG. When the ladle sliding nozzle 3 of the ladle 1 set in this way is opened, the molten metal is first charged into the main tandish 20,
It is then supplied to the twin-belt horizontal continuous caster 18 through the secondary tundish 22.

When casting molten steel using this equipment, it was found that the main tundish and child tundishes were supported by independent main tundish car and child tundash car, so they were separated from the twin-belt horizontal continuous caster. It is possible to preheat the parent tandy and child tandem independently in a wide area with good workability, and after the preheating is completed, the child tandy is first placed in a twin-belt horizontal continuous casting machine, as shown in Figure 8. It is possible to quickly and accurately carry out the work of bringing the ladle close to each other, then setting it on the parent tundish and the child tundish, and then setting the ladle on the parent tundish, as well as supplying molten steel to the twin-belt horizontal continuous caster. Fine adjustments to the amount can be made smoothly, and a predetermined amount of molten steel can be continuously supplied to the continuous caster without interruption even while changing the ladle, ensuring good working conditions until the end. I was able to maintain it.

In the apparatus shown in FIG. 8, the ladle mount 23 can be replaced with a ladle crane, a ladle car, or a ladle turret.

As described above, according to the present invention, molten metal conveyed in batches can be continuously supplied to a twin-belt horizontal continuous casting machine that requires an uninterrupted supply of molten metal in small amounts. This brings about industrially useful effects, such as making it possible to easily adjust the supply and making it easier to implement twin-belt horizontal casting of steel, which had been considered extremely difficult up until now.

[Brief explanation of drawings]

Figure 1 is a schematic diagram to explain conventional continuous casting of steel slabs, Figure 2 is a schematic diagram showing the casting state of a twin belt caster, and Figure 3 is a twin belt horizontal continuous casting for non-ferrous metals. Figure 4 is a schematic diagram showing the situation when molten metal is directly injected from the ladle into the tundish that supplies hot water to the twin-belt horizontal continuous casting machine.
A schematic diagram showing a situation in which the method shown in the figure is applied to multi-strand casting, FIG. 6 is a schematic diagram showing a situation in which the water heater of the present invention is used, and FIG. 7 is a schematic diagram showing a situation in which the water heater of the present invention is used. FIG. 8, a schematic diagram showing a situation where the present invention is applied to multi-strand casting, shows one embodiment of the present invention. In the drawings, 1... ladle, 2... molten steel, 3...
...Ladle sliding nozzle, 4...Tandate slide, 5...Tandate slide sliding nozzle, 6...Mold, 7...Slab, 8...Upper pulley, 8'...Lower pulley, 9...Top belt,
9'...Lower belt, 10...Tandateshitsu, 1
1... Gutter, 12... Edge dam, 13... Continuous melting furnace, 14... Holding furnace, 15... Gutter, 16... Flow rate control plug, 17... Float type flow rate control nozzle, 18... Twin belt horizontal Type continuous casting machine, 19...pinch roll, 20...main tandate, 21...parent tandate sliding nozzle, 22...child tandate, 2
3... Ladle mount, 24... Seal, 25... Lifting mechanism, 26... Main tray slider, 27...
Extension tube, 28...Stopper nozzle for removing residual steel, 29...Skinmer, 30...
Child train station car, 31... Parent train car running rail, 32... Child train car running rail.

Claims (1)

[Claims] 1. A parent tandy that receives molten steel from a ladle, and receives the molten steel supplied from the parent tandy and injects it into a twin-belt horizontal continuous casting machine (hereinafter referred to as twin-belt horizontal continuous casting machine). The main tandate and the child tandate are supported by separate parent and child tandates, respectively, and are parallel to the casting direction of the twin-belt horizontal continuous casting machine. A water heater for a twin-belt horizontal continuous casting machine, characterized by having a structure that allows it to move forward and backward independently.