1989 Volume 29 Issue 12 Pages 1069-1075
In continuous casing of steel, control of the teeming rate of steel from the tundish to the mold is carried out by changing the cross-sectional area of the flow channel by means of a stopper or slide gate. However, nozzle clogging or air suction occasionally occur in the controlled section, and this interferes with the degree of control of the teeming rate of steel or deteriorates the cleanness of the steel.
To improve this conventional method, some methods using a linear motor-type electromagnetic stirrer were proposed or tested, though, these methods are not yet practicable because of the difficulty of using a linear motor-type stirrer for control of the teeming rate of steel. In contrast, a rotary type stirrer is considered to be more suitable to the control of the teeming rate molten steel, because a higher intensity of stirring can be obtained through shorter affected zone by the rotary-type stirrer than by a linear motor-type stirrer.
On the basis of this idea, an electromagnetic valve using rotary-type stirrer was devised, and a series of experiments using low melting-temperature metal and molten steel were carried out to investigate the characteristics of the control and to improve the design of the electromagnetic valve. By increasing the rotational speed, the flow rate was reduced to about half of that of non-stirring when the depth of the molten steel in the tundish is 500 mm. The response of control was quick enough to apply it to steel or another high melting-temperature metal teeming as a non-contact control method.
