METHOD OF CONTINUOUS CASTING OF SMALL CROSS SECTION BILLET

摘要

A method for continuously casting a billet with a small cross section in which a curved type or vertical type continuous casting machine is used while oscillating the mold upward and downward, is characterized in that: the casting machine is provided with a mechanism for withdrawing speed oscillation wherein the mechanism comprises elastic parts either alone or in combination with dampers between the motors for driving pinch rolls at a speed corresponding to an aimed withdrawing speed and the pinch rolls, the mechanism has structural play in the directions of driving and reverse driving in such a manner that the amount of a play-incurred displacement from the neutral position of the structural play in the direction of billet driving or reverse driving is ~ 2 to ~ 30 mm in the direction of driving on the pinch roll circumferential length equivalent basis, and the mechanism produces a returning force toward the neutral position, whereby: the billet withdrawing speed during the upward period of mold oscillation becomes slower than the average withdrawing speed and during the downward period of mold oscillation faster than the average withdrawing speed; and operational parameters such as the billet length, the specific amount of secondary cooling water, the casting speed as well as the oscillation amplitude and frequency are optimized. By this method, a billet with a small cross section can be produced continuously in the condition of stable operation while stably reducing the friction force between the mold and the billet and preventing such troubles as sticking of the billet to the mold.