The tundish as a key device in the meltshop has some actual problems especially in billet continuous casting process as follows:
(1) The inner cavity shape of tundish is unreasonable. The shape of the inner cavity influences the flow of molten steel in the tundish the residence time is short, which can not play the role of purifying molten steel. The distance between the landing point of the large ladle and the nozzle of the tundish is short, or the distance difference between each nozzle is too large; The volume of the drop point of the ladle is too small, resulting in serious mixing of steel slag and serious erosion of the lining, affecting the life of the tundish and polluting the liquid steel.
(2) The tundish capacity is small, the depth of the molten pool is shallow, and it is not suitable for high-speed casting machine. The residence time of molten steel in tundish is short, so it is difficult to purify molten steel and remove inclusions. It is difficult to maintain constant casting speed when changing the bale. The slag in the tundish is agitated seriously during casting, which makes it difficult for inclusions to float and easy to enter the crystallizer, especially when the ladle is changed.
(3) Improper design of the nozzle position of the tundish, especially the nozzle on the two sides is too close to the two sides, which is easy to cause the pouring of the two side ports.
(4) The tundish nozzle control device is too thin and unreliable, it is difficult to accurately control the liquid steel flow, so that the mold liquid level is difficult to stabilize, and out-of-control accidents often occur.
(5) Large deformation of tundish and design and manufacturing accuracy problems, resulting in insufficient accuracy of multi-flow nozzle alignment.
(6) The tundish lifting device is not working, and most can not be lifted, which brings difficulties to the continuous casting process and causes many defects in the casting billet.
(7) Improper selection of the distance between the bottom of the tundish and the upper mouth of the mold. Most of the distance is too high, which brings difficulties to the nozzle alignment, and also makes the nozzle too long, which increases the consumption of resistant materials for tons of steel nozzle.
(8) Pay more attention to the quick change technology of the immersion nozzle.
In order to meet the requirements of continuous casting process with constant casting at high drawing speed, the tundish should meet the requirements of large steel volume and strength, the flow of molten steel in tundish is reasonable able to facilitate the purification of molten steel and the removal of inclusions. Some measures are available to reach good result:
(1) Optimization of tundish cavity shape
(2) tundish with large capacity deep melting pool;
(3) Prevent tundish shell deformation;
(4) Adopt solid and reliable tundish nozzle control device;
(5) The use of reliable tundish lifting device under load;
(6) Optimize the distance from tundish to mold upper mouth.
