JPH02155540A - Tundish for continuously casting metal strip - Google Patents

Abstract

PURPOSE:To execute molten metal pouring with a wide width and almost a uniform flow speed and a flow rate distribution in width direction without lowering the temp. at over-flowing hole by arranging a temp. holding vessel above the over-flowing hole near the over-flowing molten metal. CONSTITUTION:A tundish 1 sufficiently preheated is shifted so that the over-flowing hole 10 in molten metal pouring part 6 is positioned just above molten metal basin 14a in water cooled twin rolls 14 in continuous casting machine. After that, the molten metal accomodated in a ladle 25 is poured into molten metal receiving part 5 in the tundish 1 through a submerged nozzle 26 and over-flows from the over-flowing hole 10 at top part 9 through molten metal pouring hole 8 in molten metal pouring part 6 to pour into the molten metal basin 14a in the water cooled twin rolls 14. By this method, the lowering of the temp. at the molten metal pouring hole 8 and the over-flowing hole 10 is prevented and the development of solidified shell is prevented. The molten metal flowing from the molten metal pouring hole 8 to the over-flowing hole 10 becomes the pouring stream having wide width and almost uniform flow speed and flow rate distribution in the width direction.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is a method for overflowing molten metal (hereinafter referred to as molten metal) into the molten metal pool of a twin-roll type, twin belt type, etc. continuous casting machine for thin metal sheets. It is about the tundish that is easy to let flow.

[Conventional technology and its problems]

In the molten metal puddle of this type of continuous SlI machine for thin metal sheets? 8
As for the flat pouring stage for pouring hot water, Fig. 7(a) to 7.
The one shown in Figure (d) is known.

The outline and problems of the pouring means shown in FIGS. 7(a) to 7(d) will be explained below.

The device shown in FIG. 7(a) is described in Japanese Patent Application Laid-Open No. 52-38145, in which the lower end of the nozzle 42 hanging below the tundish 41 is connected to the lower end of the refractory type inclined plate 43. The welding field is brought into contact with the upper part of the slope, and an opening 44 is formed between the lower end of the nozzle 42 and the lower part of the slope of the slope plate 43, and after the welding field exits from the opening 44, it is formed on the slope. The molten metal flows down on the surface in a fan shape that widens toward the end, and is poured by the water-cooled twin rolls 45 into a molten metal pool 46 that is configured to have a wide width in the roll axis direction.

According to this method, it is relatively easy to pour molten metal over a wide width, but the flow velocity distribution in the width direction of the molten metal that spreads out in a fan shape on the slope of the inclined plate 13 is not uniform, that is, the flow velocity on both sides is uneven. is fast and the flow rate is large, so when a flow with such a velocity distribution is supplied to the molten metal pool 46, the pouring flow on both sides disturbs the scene in the molten metal pool 4G, and furthermore, the solidification generated on the roll surface is In addition to being concerned about problems such as disturbing the shell, if such disturbance occurs, there is concern that the manufactured gJ-SakaP will have hot water wrinkles and/or cracks.

The one shown in Fig. 7 is used in a pouring method called the melt drag method.
The molten metal is tightly pressed against the water-cooled twin rolls 47 of different diameters, and the molten metal is passed through the twin rolls 4 without coming into contact with the atmosphere.
The hot water is poured for 7 hours.

According to this method, the supply of molten metal between the twin rolls 47 is very stable, and it is expected that a good EJ plate will be manufactured. It must be tightly pressed against the roll 47, and there are concerns that the contact portion may be damaged due to wear, thermal load, etc., and furthermore, there may be problems such as the formation of solidified shells on the tundish 41 near the contact portion. If such a problem occurs, there is a concern that the manufactured Y↓temporary P may have defects such as hot water wrinkles, cracks, and inclusion of foreign matter.

The one shown in Fig. 7(C) has almost the same structure as the tundish conventionally used for normal continuous casting.
The lower end of the immersion nozzle 48, which is vertically installed at the bottom of the tundish 41, is placed in a molten pool 46 (constructed wide in the roll axis direction by water-cooled twin rolls 45). The molten metal is poured into the molten metal pool 46 through the nozzle 48 .

According to this method, which has been used in conventional continuous casting, the pouring itself is very simple, but since the pouring is done at one point using the immersion nozzle 48, the positive pool 46 is In addition, in the case of continuous casting of thin metal sheets, problems such as clogging of the immersion nozzle 48 and breakage of the immersion nozzle 4B may occur due to the small amount of molten metal pouring and the narrowness of the molten metal reservoir 46. There are concerns.

The one shown in FIG. 7(d) is used for a pouring method called the overflow method, in which the tundish 41 is divided into a receiving section 49 and a pouring section 55 using partition plates. The lower part 52 of the pouring port 50 is configured as an inclined surface, and the tip portion 53 thereof is configured to be wide in the roll axis direction to provide an overflow port 54, and the molten metal is poured into the pouring portion 5.
The molten metal overflows from the overflow port 54 and is poured by the water-cooled twin rolls 45 into a molten metal pool 46 configured to have a wide width in the roll axis direction.

According to this method, a wide pouring stream with a substantially uniform flow velocity and flow 1 distribution in the width direction is produced by 1+v, and the initial velocity of the pouring stream (velocity when falling from the overflow port 54) is zero. Because of this, pouring can be done very quietly and over a wide area, but the overflow port 5
In addition to the drastic temperature drop in step 4, the flow velocity and flow rate of the molten metal pouring stream are low, and solid shells are likely to form particularly on both sides of the overflow port 54. In addition to concerns about problems such as narrowing of the width, if such a problem occurs, the surface quality of the manufactured Y mm plate P will be adversely affected due to the falling off of the solidified shell.

[Purpose of the invention]

As mentioned above, each of the conventional pouring means has advantages and disadvantages. Among them, the pouring means shown in Fig. 7(d) is
Since a pouring flow with a wide width and a substantially uniform flow velocity and iA distribution in the width direction is required, continuous casting of a single metal plate, which is the object of the present invention, is particularly effective when the thickness is extremely thin and is less than 10 mm. This pouring method is considered to be suitable for continuous casting of plates with a wider width than the conventional pouring method.However, as mentioned above, in addition to the drastic drop in temperature at the overflow port 54, this pouring method Due to the low velocity and flow rate of the flow,
Solidified shells are likely to form particularly on both sides of the overflow port 54, which poses a problem that stable pouring of molten metal cannot be performed.

Therefore, the present invention solves the above-mentioned problems by providing a molten metal puddle in a continuous casting machine for thin metal sheets with a wide width and substantially uniform flow velocity and flow 1 distribution in the width direction without the temperature decreasing at the overflow port 54. It is an object of the present invention to provide a tundish for continuous casting of thin metal sheets that can be easily performed.

(Means for Solving the Problems) In order to achieve the above object, the tundish for continuous casting of thin metal sheets of the present invention has a tundish for continuous casting of thin metal sheets, in which a full molten metal is overflowed into the molten metal pool of a continuous casting machine for metal Y: thin sheets.・It is a tundish for pouring molten water, and has a bottom part made of a refractory material with good heat conductivity, which is approximately the same width as the molten pool width, and a combustion burner inside the top part of this bottom part. In addition, a heat insulator consisting of a hill portion in which the exhaust gas port of this combustion burner is provided in a direction different from the overflow port is provided close to the molten metal overflowing above the overflow port. be.

Preferably, a weir made of a refractory material with good thermal conductivity is provided on the inner front surface of the reservoir 7!1 and moves up and down toward the overflow port.

(Function) A heat insulator is provided above the overflow opening of the tundish with a width that is approximately the same as the width of the molten metal pool, and a combustion burner is provided in the heat insulator to heat the heat insulator. Since it is made of high quality refractory material, the overflow port of the tundish is reliably kept warm and the temperature at the overflow port is high. 8. It is possible to prevent the molten metal from spreading and hardening, and it is therefore possible to pour the molten metal into the molten metal pool over a wide width and with substantially uniform flow velocity and flow rate distribution in the width direction.

The reason why the exhaust gas port of the combustion burner in Insulation 2 is set in a different direction from the overflow port is because if the directions are the same, the molten metal pool directly below the overflow port is This is to prevent the flow of exhaust gas and condensation on its surface, which could cause steam to be released at the start of casting.

The bottom of the heat insulator is made of refractory material with good conductivity, which allows the entire surface of the bottom to be uniformly heated by the internal combustion and heat.
In addition, the preheating time can be shortened, and at the same time, the combustion heat can be efficiently transferred to the outer surface of the bottom and the heat retention effect can be increased. SiC, which has impact resistance, oxidation resistance, and high strength, is preferably used.

Further, it is preferable that the bottom part of the heat insulator is located above the overflow opening, at a distance of about 1 to 50 mm from the point where the molten metal is poured.

In addition, by providing a weir made of a refractory material with good thermal conductivity that moves up and down toward the overflow port on the inside front of the heat insulator, it is possible to directly immerse the weir inside the heat insulator into the molten metal. In addition to the indirect heat retention effect provided by the bottom of the heat insulator, the temperature of the molten metal can be raised smoothly.

(Embodiments) Hereinafter, embodiments of the present invention will be described based on the drawings.

Fig. 1 is a side view of the tundine, Fig. 2 is a sectional view thereof, and Fig. 3 is a view taken from arrow A in Fig. 1.

Reference numeral 1 denotes a tanditshu, which is composed of a bottomed container 2 with a refractory layered on the inner surface of an iron shell, and a lid 3 of the container 2. It is partitioned into a molten metal receiving section 5 and a molten pouring section 6. On the pouring side of the pouring part 6, the lower part 7 is composed of a pouring spout 8 having an inclined surface and an overflow port 10 at the tip end 9 of the pouring spout 8.

11 is a heat insulator, and flanges 12 provided on both sides thereof;
12 and 20 containers constituting the pouring spout 8 (!!! l Wall 13
It is fixed at 2111 on the upper surface of ゜13.

The heat insulator 11 includes a bottom part 15 made of a SiC refractory with good thermal conductivity and having a width that is approximately the same as the width of the storage tank 14a of the water-cooled twin rolls 14, and a hill part 16 at the top of the bottom part 15. This hill portion 16 is surrounded by an iron skin 17 and a refractory material 18 laminated on its inner surface, and its ceiling 1
9 is provided with four combustion burners 20 on the left and right sides of 1iilB. Further, the rear wall 21 is provided with an exhaust port 22 .

In addition, 23 is a fuel gas air pipe to the combustion burner 20.

Next, a fourth method of using the tundish 1 having the above-mentioned configuration will be described.
This will be explained based on the diagram.

The tundish l is preheated at a predetermined location by a heating burner 24 whose interior is provided above the hot water receiving part 5 and by radiant heat from the bottom part 15 due to combustion of the combustion burner 20 of the heat insulator 11. Next, the preheating by the heating burner 24 provided above the molten metal receiving section 5 is stopped, and the sufficiently preheated tundish 1 is poured into the molten metal by the overflow port 10 of the pouring section 6 into the water-cooled twin rolls 14 of the continuous casting machine. Move so that it is located directly above the pool 14a. After that, the molten metal contained in the ladle 25 is transferred to the molten metal receiving part 5 of the tundish 1 through the immersion nozzle 2.
6, the molten metal flows through the pouring port 8 of the pouring part 6, and overflows from the overflow port 10 of the tip part 9.
4)8? Pour hot water into easy pool 14a.

In this way, from the time of preheating the tandish 1, the heat insulator 1
1 continues, the temperature at the pouring port 8 and the overflow port 10 can be prevented from decreasing from the time the tundish l is moved after preheating until the start of pouring. Since the molten metal flowing from the pouring port 8 to the overflow port XO is heated from beginning to end, no solidified shell is formed during this period.The molten metal flowing from the pouring port 8 to the overflow port 10 is wide and has a high flow velocity in the radial direction. This results in a pouring flow with a nearly uniform flow rate distribution.

Actually, using the tundish l having the configuration shown in Fig. 4,
Water-cooled twin roll diameter: 400m5, width: 300m5
゜Double roll gap 7 1.5mm, angle between the line connecting the twin roll axes and the horizontal: 35 degrees, roll circumferential speed: 0.5~
Under the condition of 0.7mm/sec, width 300mm x thickness 1
．． When continuously casting a 5mm stainless steel (SUS-304) thin plate, it was found that with the conventional method in which the tundish L was preheated only by the heating burner 24 without using the H2311, both ends of the overflow port of the tundish were not used. A 'cE solid shell was formed, and as it grew, the width of the overflow opening became narrower, and an icicle-shaped solidified shell grew in front of the overflow opening, making it impossible to perform good casting. In the method of the present invention, in which preheating is carried out using both the warmer 11 and the heating burner 24, and continuous casting is performed with the warmer 11 operating after preheating, the refractory surfaces of the pouring port and overflow port after preheating are The temperature obtained was about 200'C higher than that of the conventional method, and the temperature drop until the start of casting was also extremely small compared to the conventional method. Moreover, during casting, due to the heat-insulating effect of the molten metal surface of the heat insulator 11, no solidified shell was generated at the overflow port, and stable pouring was possible over the entire width of the overflow port.

The tundish of this embodiment has almost the same structure as the tundish 1 of the first embodiment, except that the structure shown in FIGS. 5 and 6 is used in place of the heat insulator 11 of the first embodiment. The structure includes a heat insulator 27.

In the figure, the heat insulator 27 is fixed to the upper surface of both side walls 13, 13 of the container 2 constituting the pouring spout 8 with flanges 28, 28 provided on both sides of the insulator 27, as in the first embodiment. . The structure of the rear part is the same as that of the thermal insulation 2''511 described in the first embodiment.

The front structure of the heat insulator 27 is such that the front wall 29 is made up of an iron skin 30 and a refractory material 31 stacked with stones on the inner surface of the iron skin 30.
It is provided so that it can be moved up and down by a cylinder 35 using elongated holes 33.33 provided in both side walls 32.32 and bins 34.34 provided on the outside of the heat insulator 27 as guides.

Below the inner surface of the refractory 31 of the i;
A combustion burner 38 for heating the weir 36 is fixedly installed above the inner surface of the refractory 31 of the front wall 29 so as to close the opening 37 between the front wall 29 and the tip of the bottom part 17. It is set up.

Fi like this! Since the tundish 1 has the same structure, in addition to the effects of the first embodiment, when the temperature of the molten metal decreases during pouring, the cylinder 35 is actuated to drain the heated weir 36 into the overflow port 10. It is possible to prevent the formation of solidified shells by immersing it in a hot water stream. Further, by controlling the operation (2) of the cylinder 35 and controlling the amount of 3G immersion into the pouring flow (jj), the pouring flow (2) can be controlled t111.

〔Effect of the invention〕

As described above, according to the tundish for continuous casting of one metal plate according to the present invention, the molten metal pool of the continuous casting machine for fully bent thin plates can be spread over a wide width and at a flow velocity in the width direction without the temperature decreasing at the overflow port. Also, it is possible to perform pouring with a substantially uniform flow rate distribution.

[Brief explanation of the drawing]

FIG. 1 is a side view of the tundish according to the present invention, FIG. 2 is a sectional view thereof, and FIG.
FIG. 4 is an explanatory diagram of an example of the use of the tundish according to the present invention, FIGS. 5 and 6 are a side view and a sectional view of another embodiment, and FIG. 7 is an explanatory schematic diagram of the prior art. It is. Lower tip of Kundeinsh lid hot water receiving part 27 Both side walls of heat insulator container? Yong? Easily accumulating joint 31 Refractory 38 Combustion burner exhaust port 22 Heating burner immersion nozzle Both sides of steel shell Bin weir Container partition Temporary pouring section pouring port overflow port 28 Flange water-cooled double roll bottom part 30 Steel shell ceiling rear wall Fuel Gas Pipe Ladle Front Wall Elongated Cylinder Opening Patent Applicant: Kobe Steel, Ltd. Representative Patent Attorney Akira Kanemaru - Figure 1 Figure 2 Figure 5

Claims (2)

[Claims] (1) A tundish for pouring molten metal into the molten metal pool of a continuous casting machine for thin metal sheets, and the bottom part is made of a refractory material with good thermal conductivity and has a width that is approximately the same as the width of the molten metal pool. At the top of this bottom part, there is a box part that has a combustion burner inside and the exhaust gas port of the combustion burner is located in a different direction from the overflow port. A tundish for continuous casting of thin metal sheets, characterized in that it is installed close to the molten metal overflowing at the top. (2) A succession of thin metal plates according to claim 1, characterized in that a weir made of a refractory material with good thermal conductivity is provided on the inside front surface of the heat insulator and moves up and down toward the overflow port. Tundish for casting.