| 摘要 |
PURPOSE:To decrease the rate of fluctuations of a melt surface, preventing surface cracking and suppress the occurrence of breakout by providing specific fine holes on the bottom surface at the bottom end in the body part of an immersion nozzle. CONSTITUTION:In an immersion nozzle provided with plural discharge ports 2 in the body part 1 of the immersion nozzle, plural bottom surface fine holes 7, 7' having openings at the bottom face in communication with the ports 2 are provided at the bottom end of the part 1. The sectional area in the radial direction of the holes 7, 7' is set at >=0.4cm<2>, and the total of the sectional areas of all the holes 7, 7' is set at 6-30cm<2>. The angle theta' that the part 1 assumes to the central line of the pipe axis is set within 50 deg.. Namely, the angle theta, assumed by the centers of the holes 7, 7' each other at the section in the casting direction of the nozzle is set at <=100 deg. by considering the extent of melt level fluctuations, the attenuation effect of main discharge flow, etc. Thereby, the productivity is improved without causing quality in the case of high speed drawing. |
