JPS60127051A - Continuous casting method - Google Patents

Abstract

PURPOSE:To prevent solidification of a molten metal and sticking of foreign matter in an immersion nozzle in the case of supplying the molten metal through the tap hole provided in the bottom of a tundish to the inside of a casting mold by running the molten metal flowing through the tap hole in the form of a vortex. CONSTITUTION:The molten metal in a tundish 1 flows to the inside of an immersion nozzle in the state of the vortex formed by blades 9 when the molten metal flows through a tap hole 1a to the inside of the immersion nozzle. The flow rate of the molten metal flowing along the wall surface of the immersion nozzles increases accordingly without stagnating on the wall surface of the immersion nozzle. Formation of the solidified part at the top end of the immersion nozzle is therefore obviated and the sticking of foreign matter such as Al2O3 or the like on the inside wall surface of the immersion nozzle is obviated as well. Stable continuous casting is thus accomplished.

Description

Detailed Description of the Invention (Field of Industrial Application) This invention relates to a continuous casting method that is applied to manufacturing slabs by continuously supplying molten metal in a tundish into a mold. be.

(Prior art) In the continuous casting method, molten metal placed in a ladle is transferred into a tundish, and the molten metal is continuously poured into the mold through an outlet provided at the bottom of the tundish and an immersion nozzle connected to the outlet. This method is a method of continuously drawing out the formed slab by supplying the slab and solidifying it sequentially from the outer shell part in the mold, and its adoption is rapidly increasing because it is significantly superior in productivity compared to the conventional ingot-forming method. It is widespread.

Fig. 1 shows an outline of the equipment used in such a continuous casting method, in which 1 is a tundish, 1a is a tap hole provided at the bottom of the tundish 1, 2 is a molten metal, and 3 is a tundish.
4 is an immersion nozzle whose upper end is connected to the outlet 1a, 5 is a mold, 6 is a slab, and 7 is a roll. When the steel plate 3 is raised, it is supplied into the mold 5 through the outlet 1a and the immersion nozzle 4, and solidified in the mold 5 sequentially from the outer shell part to form the slab 6, which is continuously guided by the rolls 7. pulled downwards.

In continuous casting using such a device, the temperature of the molten metal 2 in the tundish 1 is such that solidification occurs rapidly in the mold 5 and the secondary cooling zone behind it, and at the same time a good solidification structure and macro segregation are formed. It is desirable to keep the temperature of the molten metal 2 as low as possible, but when the temperature of the molten metal 2 is lowered in this way, a solidified portion 8 as shown in FIG. 1 is formed particularly at the upper end portion of the immersion nozzle 4. However, by reducing the opening diameter of the immersion nozzle 4 and reducing the flow rate of the molten metal 2, the level of the molten metal in the mold 5 may drop, which may impede continuous casting. In addition, when the molten metal 2 contains a large amount of AM as a deoxidizing agent or as an alloy additive element, when this AM is oxidized to produce A, 03, this An, 03 or the immersion nozzle 4 This has the problem of adhering to the inner wall of the nozzle and causing nozzle blockage or breakout.

(Purpose of the Invention) This invention has been made by focusing on the problems of the conventional art as described above. To provide a continuous casting method that prevents foreign matter from adhering to the inner wall part of a immersion nozzle, thereby stably supplying molten metal through the immersion nozzle, and continuously producing slabs. The purpose is to

(Structure of the Invention) The present invention provides a continuous casting method in which molten metal in a tundish is supplied into a mold through a tap provided at the bottom of the tundish, in which the molten metal flowing from the tap is made to flow as a vortex. It is characterized by

(Embodiment 1) FIG. 2 is a diagram showing Embodiment 1 of the present invention, and the same parts as in FIG. 1 are given the same reference numerals and the explanation thereof will be omitted.

In this embodiment 1, as shown in the figure, the tandish 1
The figure shows a case where a plurality of blades 2 (5'a, 9b, 9c, 9d) are provided at 90° intervals on the bottom surface of the tap 1, substantially concentrically with the tap 1a.

Therefore, the molten metal in the tandish 1 (for example,
(molten metal of structural steel with A content of 0.1 to 1.0% by weight)
2 flows into the immersion nozzle 4 through the outlet 1a,
The molten metal 2 flows into the immersion nozzle 4 in a vortex state by the blade 2. Therefore, the molten metal 2 flowing along the wall surface of the immersion nozzle 4 has a size of 7Q $ at, and the molten metal 2 stays on the wall surface of the immersion nozzle 4. Therefore, the solidified portion 8 shown in FIG. 1 will not be formed at the upper end of the immersion nozzle 4 as in the conventional case, and foreign matter such as Al 203 will not adhere to the inner wall surface of the immersion nozzle 4. This makes it possible to perform stable continuous casting.

(Embodiment 2) FIG. 3 is a diagram showing Embodiment 2 of the present invention, in which the same parts as in FIG.

In this second embodiment, as shown in the figure, a plurality of blades 10 (10a,
10b, 10c-.

10d) are provided at 90° intervals.

Therefore, when the molten metal 2 in the tundish 1 flows into the immersion nozzle 4 through the outlet 1a, the molten metal 2
flows into the immersion nozzle 4 in a vortex state by the blades 10. Therefore, as in the case of Example 1, the flow velocity of the molten metal 2 flowing along the wall surface of the immersion nozzle 4 increases, and the molten metal 2 does not stay on the wall surface of the immersion nozzle 4, so that the molten metal 2 flows in the immersion nozzle 4. In addition to being able to obtain the same effect as in the case of , it is also possible to change the degree of formation of the vortex by adjusting the height of the stopper 3.

In addition, a blade 10 is provided on the stopper 3, and at the same time, a blade 2 is also provided on the bottom surface of the tundish 1 in the same manner as in the first embodiment, and both blades 2.10 cause the molten metal 2 flowing through the outlet 1a to become a vortex. It is also possible to do so.

(Effects of the Invention) As described above-1-, according to the present invention, in the continuous casting method in which the molten metal in the tundish is supplied into the mold from the outlet provided at the bottom of the tundish,
Since the molten metal flows from the outlet as a vortex, it is possible to prevent the molten metal from solidifying at the immersion nozzle part as in the conventional case, and to prevent foreign matter such as An, 03, etc. from forming on the inner wall of the immersion nozzle. It is possible to prevent re-breakout, which can cause continuous casting to become unstable due to a decrease in the opening diameter of the immersion nozzle or blockage, and to avoid This method has the very excellent effect of making it possible to produce high-quality slabs with little variation in solidification structure and macro-segregation through stable operations.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a continuous casting apparatus using a conventional continuous casting method, FIG. 2 is a perspective view of the bottom portion of a tundish according to Embodiment 1 of the present invention, and FIG. 3 is a longitudinal cross-section of a tundish portion according to Embodiment 2 of the present invention. It is a front view. 1... Tundish 1a... Tap spout 2... Molten metal 3... Stopper 4... Immersion nozzle 5... Mold 6... Slab 2.10... Blade. Patent Applicant Daido Steel Co., Ltd. Representative Patent Attorney Yutaka Oshio Figure 1 Figure 2 Me I Figure 3

Claims (1)

[Claims] (1) A continuous casting method in which molten metal in a tundish is supplied into a mold from a spout provided at the bottom of the tundish, characterized in that the molten metal flowing from the tap is made to flow as a vortex.