JPH0347658A - Method for pouring molten metal in strip continuous casting apparatus - Google Patents

Abstract

PURPOSE:To prevent involution of gas, such as air, into a molten metal pouring nozzle and to make molten metal flow from the pouring nozzle into a mold quiet and uniform over the whole width of the mold by arranging a reducer having opening area equal to or less than the outlet area of the pouring nozzle to inlet of a molten metal preliminary chamber and pouring the molten metal. CONSTITUTION:Under condition of opening the molten metal discharging hole 2 by ascending a slide valve 3 to the prescribed position and closing the molten metal discharging hole 6 in the molten metal preliminary chamber 5 with a stopper 7, the molten metal 10 is received to a tundish 1 from a molten metal vessel, such as ladle. After the prescribed quantity of molten metal 10 is filled in the tundish 1, by descending the slide valve 3, an orifice 4 is positioned to the discharging hole 2, and by opening the stopper 7, the molten metal is poured into the mold 9 for strip through the pouring nozzle 8. After that, by controlling the molten metal 10 head in the tundish 1 while pouring the molten metal 10 into the tundish 1 from the molten metal vessel during continuously casting, the molten metal is poured while adjusting the normal flowing rate into the mold.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a pouring method in a thin plate continuous casting apparatus that directly produces thin plates (C5ON11 and below) from molten metal. Molten metal includes not only steel but also aluminum, copper, etc.

[Conventional technology]

As shown in Figure 4, the thin plate continuous casting equipment has the following features:
A tundish 15, a tap 16 opening on the side of the bottom of the tundish 15, connected to the outlet side of the tap 16, and having a cross-sectional shape similar to the cross-sectional shape of the thin plate to be cast. Generally, it is composed of a pouring nozzle 17 and a thin plate mold 18 such as a water-cooled roll provided close to the tip of the pouring nozzle 17, and the method of pouring the metal into the mold 18 using this device is performed using a ladle (not shown). The molten metal 19 is received into the tundish 15 from a molten metal container such as the like, and the molten metal 19 received in the tundish 15 is poured into the mold 18 through the pouring nozzle 17.

On the other hand, Japanese Patent Application Laid-Open No. 62-248543 discloses that the pouring nozzle 17 of the above-mentioned continuous thin plate casting apparatus has a cross-sectional shape of an inlet side 17a and an outlet side 17b, respectively, from circular to circular as shown in FIG. 5a. The shape is similar to a rectangular shape and the flat shape, and the cross section between them changes continuously, and the entrance side 1
It is disclosed that the cross-sectional area ratio between 7a and the outlet side 17b is 1 or more. According to this pouring nozzle 17,
Since the cross-sectional shape of the inlet side 17a is circular or rectangular, and the difference in vertical and horizontal dimensions is as small as possible, the molten metal 19 at a uniform temperature can be poured into the mold 18. Also, entrance side 17
a to the outlet side 17b, the cross-sectional shape is continuously changed to the flat cross-sectional shape of the outlet side 17b, and the inlet side 1
Since the cross-sectional area ratio between the molten metal 7a and the outlet side 17b is set to 1 or more, the molten metal 1 entering the pouring nozzle 17 as shown in FIG.
9 is said to be able to smoothly flow as shown by the arrow without disturbance at the inner end 17c of the pouring nozzle 17 and to be widened, thereby preventing defects on the surface of the slab.

[Problem to be solved by the invention]

By the way, in the pouring method using the thin plate continuous casting apparatus shown in FIG.
The flow of the molten metal 19 immediately after exiting the pouring nozzle 17 shrinks within the inlet of the pouring nozzle 17, and as a result, the contracted part becomes a negative pressure state. The flow 19 becomes turbulent, and it is not possible to obtain a quiet and uniform flow of the molten metal over the entire width from the pouring nozzle 17 to the mold 18, which is important in thin plate casting. For this reason, the cast thin plates have surface defects and the like, which not only result in poor quality, but also impede the productivity of the continuous thin plate casting apparatus.

In addition, in the pouring method using the thin plate continuous casting apparatus disclosed in JP-A No. 62-248543, the turbulent flow of the molten t&19 in the pouring nozzle is prevented, and the molten metal flows from the pouring nozzle 17 to the mold 18. However, in continuous thin plate casting, the nozzle exit width on the pouring nozzle outlet side 17b must be widened, and the nozzle exit height must be increased to a certain extent to prevent the molten metal 19 from solidifying at the nozzle exit. Therefore, it was necessary to remove the
If the cross-sectional area of the inlet side 17a is made larger than the cross-sectional area of the outlet side 17b, as in the pouring nozzle I7 disclosed in Publication No. 43, the flow rate must basically be throttled at the outlet side 17b, and the outlet side 17b Since the nozzle exit width must be increased, the nozzle exit height must necessarily be set to a very small value, such as 1 to 2 mm.
As described above, there is a problem that the nozzle exit area cannot be made wide.

The present invention was made in view of the above problems, and it prevents gases such as air from getting into the pouring nozzle, and allows the molten metal to flow quietly and uniformly from the pouring nozzle to the mold over the entire width of the mold. It is an object of the present invention to provide a pouring method in a thin plate continuous casting apparatus that allows for a smooth flow and a wide nozzle exit area.

[Means to solve the problem]

In order to achieve the above object, a pouring method in a thin plate continuous casting apparatus according to the present invention is a method for pouring molten metal in a tundish into a mold of a thin plate continuous casting apparatus through a pouring nozzle. A molten metal pouring preliminary chamber is provided in front of the molten metal pouring chamber, and at the entrance of the molten metal pouring preliminary chamber, a restriction having an area smaller than the outlet area of the molten metal pouring nozzle is provided to pour the molten metal.

[For production]

In the present invention, a molten metal pouring preliminary chamber is provided in front of the molten metal pouring nozzle, and a molten metal is poured by providing a restriction having an area smaller than the outlet area of the molten metal pouring nozzle at the entrance of this molten metal pouring preliminary chamber, so that the flow of the molten metal is as follows. Immediately after passing through the throttle installed at the entrance of the pouring preliminary chamber, the molten metal becomes thicker (reduced) and turbulence occurs in the pouring preliminary chamber, but this turbulence in the molten metal flow is absorbed in the pouring preliminary chamber and reaches the inside of the pouring nozzle. In addition, even if air or other gas is entrained by the negative pressure generated from the contracted flow behind the throttle, it will accumulate in the upper layer of the pouring preliminary chamber and will not affect the inside of the pouring nozzle. Therefore, the molten metal flow in the pouring nozzle does not involve gases such as air, and moreover, a quiet and uniform flow can be obtained over the entire width of the mold.

Additionally, as mentioned above, turbulence in the molten metal flow and entrainment of gases such as air are absorbed in the pouring preliminary chamber and are unlikely to affect the inside of the pouring nozzle, so the outlet area of the pouring nozzle should be widened. This allows continuous casting of thin plates without solidifying the molten metal at the nozzle outlet.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a conceptual cross-sectional view of a thin plate continuous casting apparatus according to the present invention. In the figure, 1 is a tundish, 2 is a tap opening opening on the side of the bottom of the tundish 1, and 3 is a tap facing the tap 2. A slide valve is equipped with an orifice 4 at a position and is slidably provided inside the tap 2, 5 is a pre-pouring chamber provided outside the tap 2, and 6 is a preliminary molten pouring chamber 5.
7 is a stopper slidably provided inside the tap 6, 8 is a pouring nozzle provided outside the tap 6, and 9 is a thin plate mold. Molten metal pouring by this thin plate continuous casting apparatus is performed with the slide valve 3 raised to a predetermined position to open the tap hole 2, and with the tap hole 6 of the pouring preliminary chamber 5 closed by the stopper 7. Molten metal 10 is received into the tundish 1 from an outside molten metal container such as a ladle, and after a predetermined amount of molten metal 10 fills the tundish 1, the slide valve 3 is lowered to position the orifice 4 at the outlet 2, and the stopper 7 is opened and the metal is poured into the thin plate mold 9 via the pouring nozzle 8. After this, during continuous casting, while pouring the molten metal 10 from the molten metal container into the tamp tundish 1, the head of the molten metal 10 in the tundish 1 is controlled to adjust the specified flow rate to the mold. .

Actually, by the above method, the inner diameter of the orifice 4 was set to 50+
Using the slide valve 3 formed to a thickness of 50 m, the molten steel is
As a result of a water model experiment in which a thin plate with a width of 600 mm and a thickness of 600 mm was conducted, the flow of pouring metal from the pouring nozzle 8 to the mold 9 was as follows.
A quiet, uniform flow without entrainment of gases such as air was obtained over the entire width of the tube.

Incidentally, in the above embodiment, the pre-pouring chamber 5 is provided as a tundane shell.
Although the thin plate continuous casting apparatus has been described by way of example, the thin plate continuous casting apparatus may be provided with the pouring preliminary chamber 5 integrally provided at the bottom of the tundish 1.

Specifically, as shown in FIG. 2, a pre-pouring chamber 5 is integrally provided at the bottom of the tundish 1.
An orifice 4 is opened in the inner side wall of the molten metal, and an outlet 6 is opened in the outer side wall of the molten metal.The upper wall of the molten metal pouring preparatory chamber 5 is provided with an orifice 4 and an inlet for venting gas such as air and for inflowing the molten metal 1o into the molten metal pouring preparatory chamber 5. 11 is open, a pouring nozzle 8 is provided outside the outlet 6, and a stopper 12 that can be opened and closed is provided above the inlet 11. As shown in the figure, the orifice 4 is provided in the earthen wall of the pouring preliminary chamber 5, and a stopper 13 that can be opened and closed is provided on the top of the orifice 4. A thin plate continuous casting apparatus having the same configuration may also be used.

According to the thin plate continuous casting apparatus shown in FIG. 2, in addition to obtaining the same effects as in the above embodiment, gas such as air accumulated above the pouring preliminary chamber 5 can be extracted from the inlet 11. Further, according to the thin plate continuous casting apparatus shown in FIG. 3, in addition to the above-mentioned effects, the orifice 4 is further provided with a stopper 13 that can be opened and closed. In addition to being adjustable, if an emergency such as a breakout occurs during casting, it can be dealt with by closing the stopper 13.

〔Effect of the invention〕

As described above, according to the pouring method in the thin plate continuous casting apparatus according to the present invention, entrainment of gas such as air in the pouring nozzle is prevented, and the molten metal flow from the pouring nozzle to the mold is controlled over the entire width of the mold. The flow can be made quiet and uniform over the entire length, and a thin plate with good surface quality without entrainment of gases such as air can be obtained, which in turn can improve the productivity of the continuous thin plate casting apparatus.

In addition, the outlet area of the pouring nozzle can be widened, and thin plates can be continuously cast without the molten metal solidifying.

[Brief explanation of drawings]

FIG. 1 is a conceptual cross-sectional diagram of a thin plate continuous casting apparatus according to the present invention, FIGS. 2 and 3 are cross-sectional conceptual diagrams of a separate layer type continuous thin plate casting apparatus according to the present invention, and FIG. 4 is a conventional FIG. 5 is a cross-sectional conceptual diagram of a thin plate continuous casting apparatus of 1, and is an explanatory diagram of a conventional pouring nozzle.

Claims (1)

[Claims] (1) In a method of pouring molten metal in a tundish into a mold of a continuous thin plate casting machine through a pouring nozzle, a preliminary pouring chamber is provided in front of the pouring nozzle, and the entrance of the preliminary pouring chamber is A method for pouring molten metal in a thin plate continuous casting apparatus, characterized in that molten metal is poured by providing a restriction that is smaller than the outlet area of a molten metal pouring nozzle.