JPH0320297B2 - - Google Patents

Description

[Detailed description of the invention]

(Related Industrial Field) The present invention relates to a water heater in a continuous track casting facility. (Prior art) When continuous casting is performed by flowing molten metal using a continuous track casting machine, the three-stage hot water supply method shown in Figure 5 is currently the optimal method from an operational and quality standpoint. It is used. This device will be briefly explained with reference to FIG.
1 is a ladle, and 3 is a primary tundish connected through an inert gas shield 2. Reference numeral 4 designates a flow rate control nozzle, and the molten metal 8 is supplied from the submerged nozzle 5 to the secondary tundish 6 under the control of this nozzle. The molten metal 8 in the secondary tundish 6 is sent from the hot water supply trough 7 to a continuous track casting machine 9, where a slab 10 is cast. Now, such a three-stage hot water supply type continuous casting machine has the following features 1) to 3). 1. The molten metal from the ladle is temporarily retained in the primary tundish 3, and impurities in the molten metal are floated to improve the cleanliness. 2. Since the upper layer of the molten metal in the primary tundish 3 is contaminated with floating impurities, it is necessary to drain the molten metal with higher purity than the bottom.
For this reason, a hot water flow control nozzle 4 is installed at the bottom of the primary tundish 3, but in this case, the nozzle position is located at the primary tundish 3.
Since the static pressure of the molten metal inside acts on the nozzle hole, the larger the static pressure, the smaller the nozzle hole diameter relative to the required flow rate of hot water supply. 3. When supplying hot water in the caster, it is desirable that the amount of hot water supplied be as uniform and smooth as possible in the width direction of the slab in view of the quality of the slab. For this purpose, it is not preferable to directly feed the molten metal from the hot water supply control nozzle into the caster, but the flow rate is once lowered in the secondary tundish 6 so that it overflows from the gutter in a uniform flow. However, this three-stage hot water supply method has the disadvantage that the temperature of the molten metal decreases significantly from the time when the hot water is supplied from the ladle 1 into the caster. For example, when casting steel, the temperature θo of the molten steel tapped from the converter into the ladle 1 is about 100 to 150 by the time it enters the secondary tandem.
The temperature will drop by ℃. Therefore, if the tapping temperature is too low, the temperature in the secondary tundish hot water supply gutter 7 will drop to near the solidification temperature of the molten steel, and metal will adhere to the top surface of the gutter, disrupting the flow of hot water and making it difficult to supply hot water properly. The level of molten steel fluctuates rapidly, and molten steel often overflows from the caster, which is extremely dangerous. On the other hand, setting the tapping temperature of molten steel high in advance in anticipation of this temperature drop will significantly shorten the life of the refractory bricks in the converter (electric furnace), and will also require extra energy, leading to an increase in running costs. It turns out. Furthermore, the mold wall of the endless track may be damaged by melting. Next, the generation of inclusions due to secondary oxidation of molten metal causes defects during rolling of the product, so like impurities, it must be prevented as much as possible. This promotes secondary oxidation due to oxygen in the air, which is unfavorable in terms of product quality. In addition, regarding the controllability of the flow rate of hot water, there is a delay in the response of the flow rate control nozzle 4 of the primary tundish 3 to the secondary tundish, making it difficult to quickly and properly control the level of molten metal in the caster. Therefore, level control is generally performed by controlling the casting speed of the caster, and the primary tundish 3
The flow rate control nozzle 4 is merely an auxiliary one. Therefore, the casting speed of the caster constantly fluctuates, resulting in unfavorable hot water wrinkles and double skin defects on the surface quality of the slab. Furthermore, since the casting speed cannot be kept constant, it has been difficult to carry out continuous casting and continuous rolling that is directly connected to a rolling mill located behind the caster. (Problems to be Solved by the Invention) In view of the above-mentioned drawbacks of the prior art, the present invention reduces the temperature drop of the molten metal, suppresses the occurrence of secondary oxidation of the molten metal, and uses only the flow rate control nozzle 4 of the primary tundish 3. The objective is to enable casting at a constant speed using a continuous track casting machine. (Solving Means by the Invention) A tundish dish that is partitioned by a skimmer into two chambers, a large-capacity chamber A leading to a ladle and a small-capacity chamber B leading to a hot water supply gutter, and each partitioned chamber is provided with an upper nozzle at the bottom, respectively; an upper fixing plate provided at the bottom of the tundish and having holes concentric with the upper nozzles and corresponding to the upper nozzles, a slide plate located at the lower part of the upper fixing plate and having elongated holes, and a lower part of the slide plate. and a lower fixed plate having an emergency hot water discharge nozzle provided in the upper fixed plate, and the sliding plate is operated by a stroke control device and slides to put the two holes provided in the upper fixed plate into a communicating/non-communicating state. It is possible,
It is also characterized in that the hole on the small capacity chamber B side and the emergency hot water discharge nozzle of the lower fixed plate can communicate with each other. (Embodiments of the invention) Examples of the invention will be described with reference to FIGS. 1 to 3. In the present invention, since the secondary tundish 6 in the configuration shown in FIG. 5 is omitted, the flow rate control nozzle 4 is
and the shape of the primary tundish 3 is improved. Numeral 11 is only one tundish in the present invention, and two upper nozzles 13 and 14 are set in a mass brick 12 (FIG. 3) for a flow rate control nozzle disposed at the bottom of the tundish 11. A skimmer 15 is installed upright between the two upper nozzles 13 and 14, and
The skimmer 15 temporarily stores the molten metal from the ladle 1 and cleans it by floating impurities in the large capacity chamber A, and the hot water supply gutter 1 for supplying hot water to the caster.
It is partitioned into a small capacity chamber B having 6. The flow rate control nozzle part has an upper fixing plate 17, a slide plate 18, a lower fixing plate 19, and a slide plate 18.
It is composed of a stroke control device 20 that slides in the direction of the arrow in the figure, and an emergency hot water discharge nozzle 21. The upper fixing plate 17 is provided with two equally spaced and concentric holes 13a and 14a, the diameter of which is equal to or slightly larger than the nozzle holes of the upper nozzles 13 and 14 set in the mass brick 12. The slide plate 18 is provided with a long hole 18a extending between the holes 13a and 14a formed in the upper fixed plate 17. Lower fixing plate 1
9 prevents the molten metal 8 from leaking from each mating surface, and the slide plate 18 is controlled by the stroke control device 20.
The slide plate 18 is sandwiched between the upper fixed plate 17 and the upper fixed plate 17 with an appropriate pressing force so that the upper fixed plate 17 can slide smoothly. (Function) The supply of hot water from the ladle 1 to the caster will be described below with reference to FIGS. 4a to 4d. 1. When the slide plate 18 is in the position shown in FIG. Upper fixing plate 1
7 and ejects into the small volume chamber B on the right side of the skimmer 15. 2. When the slide plate 17 is moved in the direction of the arrow by the stroke control device 20 to the position b in FIG. The flow rate passing to the right side of the skimmer 15 is reduced. That is, the flow rate is controlled by adjusting the amount by which the hole area of the hole 13a is narrowed by the stroke control device 20. 3. When the slide plate 18 further moves to the position shown in FIG. 4c, the hole 13a is completely closed and hot water supply is stopped. 4 At the end of casting or during an emergency stop, etc., when the slide plate 18 is stroked to the position d in Fig. 4, the molten metal 8 in the small volume chamber B on the right side of the tundish, which is partitioned by the skimmer 15, slides from the hole 14a. Hole 19 via long hole 18a of plate 18
It is discharged from a. In this case, the required area S of the hole 13a is
Assuming that the level difference h (Fig. 3) of the molten metal 8 between the large capacity chamber A on the left side and the small capacity chamber B on the right side of 5 is v=C・√2 …(1) Q=S・v …(2 ) Here, C: discharge coefficient, v: flow velocity, Q: flow rate From equations (1) and (2),

[Formula] becomes. From this formula, the molten metal 8 in the tundish 11 is
Compared to the conventional case in which the static pressure H directly affects the nozzle area S, the nozzle area S can be made much larger in the present invention because the static pressure acts on the level difference h between the large capacity chamber A and the small capacity chamber B. This reduces the influence of nozzle clogging on flow rate changes. (Effects of the invention) (1) Since the temperature drop of the molten metal can be reduced, the temperature in the melting furnace can be lowered, energy saving is possible, and the life of the refractory in the furnace can be extended. , there is no melting damage to the endless track mold wall, making it safer and significantly reducing the cost of the product. (2) When the temperature drop of molten metal is reduced, base metal adhesion due to solidification during hot water supply is eliminated, a uniform flow of hot metal can be maintained, and stable operation is possible. (3) Secondary oxidation of molten metal during hot water supply can be reduced, greatly improving product quality. (4) Since the nozzle hole area can be made larger, nozzle clogging is less likely to occur and operation is stable. (5) Controllability with the flow rate control nozzle is improved, and the level of molten metal in the caster can be controlled without controlling the caster casting speed, making constant speed casting possible and improving the surface quality of the slab. At the same time, continuous operation directly connected to the rolling mill becomes possible. (6) A caster casting speed control device for controlling the level of hot water in the caster is not required, and a secondary tundish is also not required, so equipment costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 shows a water heater according to the present invention. Figure 2 is a detailed cross-sectional view of the tundish water supply section. FIG. 3 is a detailed view of the hot water supply section, and is a sectional view taken along the - arrow in FIG.
FIG. 4 is an explanatory diagram of the operation of the hot water supply section. Figure 5 shows a conventional water heater (partial cross section). In the figure: 1... Ladle, 2... Inert gas shield, 3... Primary tundish, 4... Flow rate control nozzle, 5... Immersion nozzle, 6... Secondary tundish, 7... Hot water supply gutter, 8 ...molten metal, 9
...Continuous track continuous casting machine, 10...Slab, 11...
...Tandaitsuyu, 12...Masurenga, 13,
14...Upper nozzle, 13a, 14a...(upper fixing plate) hole, 15...Skimmer, 16...Hot water gutter,
17... Upper fixing plate, 18... Slide plate, 18a
...Elongated hole (of the slide plate), 19...Lower fixing plate,
19a... Hole in lower fixing plate, 20... Stroke control device, 21... Emergency hot water discharge nozzle, 22... Emergency hot water drainage pot.

Claims (1)

[Claims] 1. A tundish that is divided by a skimmer into two chambers, a large-capacity chamber A leading to the ladle and a small-capacity chamber B leading to the hot water gutter, and each of the partitioned chambers is equipped with an upper nozzle at the bottom, and a tundish can is installed at the bottom of the tundish an upper fixing plate that is concentric with the upper nozzles provided and has holes corresponding to the upper nozzles, a slide plate that is located at the bottom of the upper fixation plate and has elongated holes, and an emergency exhaust provided at the bottom of the slide plate. and a lower fixed plate having a hot water nozzle, and the slide plate is operated by a stroke control device to slide, and can put two holes provided in the upper fixed plate into a communicating state or a non-communicating state, and A hot water supply device for continuous track casting equipment, characterized in that a hole on the small capacity chamber B side can communicate with an emergency hot water discharge nozzle on a lower fixed plate.