Method and device for continuous thin strip casting

Abstract

A method for continuous thin strip casting comprises: introducing molten steel through a long nozzle into a tundish from a ladle, the tundish is one strand tundish, and the molten steel flows below a weir, then passes a first dam and enters a channel with an induction heating device, and the heated molten steel then flows out from an outlet at the other side of the tundish to a nozzle also with an induction heating device for casting. The distances between the weirs of the tundish and the channel have optimal distance ranges. The present invention can improve the casting stability and the quality of the casting strip.

Claims

1. A method for continuous thin strip casting comprising: providing molten steel by pouring the molten steel from a ladle through a long nozzle into a tundish; and heating the molten steel by heating a channel inside the tundish through which the molten steel flows to maintain the molten steel at an approximately constant temperature during the pouring, wherein a first induction heater is disposed outside of a nozzle disposed at a first side of the tundish, wherein further, the molten steel flows below a weir located at the first side of the tundish; the molten steel passes a first dam and enters the channel, the channel having a second induction heater for induction heating of the molten steel, wherein further, a temperature of the molten steel after induction heating is 3050 C. higher than that of the molten steel provided into the tundish; and the induction heated molten steel flows out from an outlet at a second side opposite the first side of the tundish to the nozzle for casting the induction heated molten steel.

2. The method for continuous thin strip casting according to claim 1, wherein a distance between the first induction heater disposed outside of the nozzle and an upper port of the nozzle is approximately to approximately of the distance between an inlet and an outlet of the tundish.

3. The method for continuous thin strip casting according to claim 1, wherein the molten steel after induction heating passes a second dam and the molten steel flows out from the outlet at the second side of the tundish for casting.

4. A tundish for continuous thin strip casting, wherein the tundish comprises a tundish inlet, a weir, a first dam, a retaining wall separating the tundish into two chambers, a tundish outlet, and a nozzle disposed proximate to the tundish outlet; wherein the retaining wall is provided inside the tundish with a channel which impenetrates two chambers; wherein the channel is surrounded by a first induction heater, the first induction heater comprising an iron core, a coil, a refractory material and a tube; and wherein a second induction heater is disposed outside of the nozzle; wherein the tundish is further configured such that, molten steel flows below the weir located at a first side of the tundish; the molten steel passes the first dam and enters the channel, where the first induction heater induction heats the molten steel, wherein further, a temperature of the molten steel after the induction heating by the first induction heater is 3050 C. higher than that of the molten steel provided into the tundish; and the induction heated molten steel flows out from the tundish outlet at a second side opposite the first side of the tundish to the nozzle for casting the induction heated molten steel.

5. The tundish for continuous thin strip casting according to claim 4, wherein the tundish further comprises a second dam.

6. The tundish used for continuous thin strip casting according to claim 4, wherein a distance between the tundish inlet and the retaining wall is approximately to approximately of a distance between the tundish inlet and the tundish outlet.

7. The tundish for continuous thin strip casting according to claim 4, wherein a distance between the retaining wall and the tundish outlet is approximately to approximately of a distance between the tundish inlet and the tundish outlet.

8. The tundish for continuous thin strip casting according to claim 4, wherein a distance between the weir and the retaining wall is approximately to approximately of a distance between the tundish inlet and the retaining wall.

9. The tundish for continuous thin strip casting according to claim 4, wherein a distance between the first dam and the retaining wall is approximately to approximately of a distance between the tundish inlet and the retaining wall.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a structural schematic diagram of an embodiment of present invention.

(2) FIG. 2 is a structural schematic diagram of the tundish in the embodiment of the present invention.

(3) FIG. 3 is a structural schematic diagram of the nozzle in the embodiment of the present invention.

(4) FIG. 4 is a structural schematic diagram of the tundish induction heater in the embodiment of the present invention.

EMBODIMENTS

(5) As shown in FIG. 1FIG. 4, the present invention relates to a method for continuous thin strip casting, wherein the molten steel is introduced into a tundish 1 from the ladle through the long nozzle. The tundish is a one strand tundish, and the molten steel flows below a weir 2 which is located at on one side in the tundish 1, then passes a first dam 3 and enters a channel 4 with an induction heating device; and a temperature of the molten steel after induction heating is 3050 C higher than that at a time of it is introduced into the tundish, and the heated molten steel then flows out from a outlet on the other side of the tundish 1 into the nozzle 5 for casting.

(6) Further, a nozzle induction heater 6 is disposed outside of the said nozzle 5.

(7) The distance between the induction heating device disposed outside of the nozzle and an upper port of the nozzle is of that between an inlet and an outlet of the tundish.

(8) Further, the molten steel after induction heating passes a second dam 7 and then flows out from the outlet at the other side of the tundish for casting.

(9) A tundish used for continuous strip casting in the present invention, wherein the tundish 1 is provided inside with the tundish inlet 101, the weir 2, the first dam 3, the retaining wall 100 which separates the tundish into two chambers and the tundish outlet 102 in this order; the retaining wall 100 is provided inside with a channel 4 which impenetrating two chambers; and the retaining wall around the steel channel 4 is provided inside with an induction heater 8.

(10) Further, the chamber corresponding to the tundish outlet 101 is also provided with a second dam 7.

(11) A distance B between the tundish inlet and the retaining wall is of a distance A between the tundish inlet and the tundish outlet. A distance C between the retaining wall and the tundish outlet is of the distance A between the tundish inlet and the tundish outlet. A distance D between the weir and the retaining wall is of the distance B between the tundish inlet and the retaining wall. The distance E between the first dam and the retaining wall is of the distance B between the tundish inlet and the retaining wall.

(12) According to the capacity of the ladle 10 and considering the temperature decline of the ladle 10, the temperature of the molten steel is heated to a superheat degree of 50100 C, and the molten steel is introduced through the long nozzle 11 into the tundish 1. After the molten steel passes through the weir 2 and the first dam 3, then flows into the channel 4 which is induction heated by the induction heater 8; the heater heats the molten steel flowing through the channel by an external power source.

(13) At the preliminary stage of pouring, the induction heater 8 is set at a high power to increase the temperature of the molten steel in the tundish 1 by 3050 C. Besides, a nozzle induction heater 6 is provided at outside of the nozzle 5 to heat the molten steel passing through the nozzle 5 at the preliminary stage of pouring. In this way, at the preliminary stage, a superheat degree of the molten steel entering into the nozzle 5 and delivery device 12 can reach 80150 C. The chances of condensation of the high-temperature molten steel have been reduced when flowing through the small hole of the delivery device, the pouring process can be smoothly carried out.

(14) When the molten steel ceaselessly flows from the delivery device 9 to the location between twin rollers 12, the molten steel in the molten pool between twin rollers 12 accumulates and forms a molten pool 13, and when the liquid level of the molten pool 13 reaches a certain height, the heat accumulation of both the nozzle 5 and delivery device 9 becomes adequate. At this moment, the power of the induction heater 8 in the tundish 1 is lowered, so that the molten steel is poured with a normal superheat degree, and the electrical source of the nozzle induction heater 6 is switched off

(15) In case of long-time pouring, according to the requirement of maintaining a basically stable superheat degree for the molten steel, the power of the induction heating device 8 is regulated to realize constant-temperature pouring in casting process. The molten steel solidifies between twin rollers 12, forms a shell, and then forms a cast strip 14 through extrusion by twin rollers, and finally produces a coil 15 through coiling by a coiling machine.

(16) Continuous thin strip casting technology is one of the most competitive technologies in the 21.sup.th century, and has many incomparable advantages compared with conventional continuous casting, such as energy conservation, environmental protection, etc., so it is increasingly emphasized by various countries in the world. As the tundish and delivery device pouring system constitute the key process and device in continuous thin strip casting, the present invention, by proposing the above method and device, will improve the stability of continuous thin strip casting significantly and lay a solid foundation for the successful realization of continuous thin strip casting.