Pouring nozzle for a steel melt using continuous casting moulds with mould walls revolving in the pouring direction

摘要

1. A casting nozzle mouthpiece (1) for continuous casting moulds receiving molten steel and having, following in the casting direction (4), walls having a rectangular external cross-section and a bore (5) of rectangular cross-section which widens funnel-fashion in the casting direction (4) and is bounded on the narrow sides (3) and wide sides (2) by convexly curved wall portions having radiuses of curvature constant in the casting direction (4), the radiuses of curvature of the bore walls being a multiple of the distance between the initial cross-section (8) of the mouthpiece (1), with top and bottom bore wall (7) extending parallel with the longitudinal axis, and its outlet cross-section (9), characterized in that the bore side walls (6) bearing against the narrow sides (3) of the mouthpiece (1) are also convexly curved in the direction of the longitudinal axis (1') in a vertical plane transverse thereto, the last-mentioned transverse curvature decreasing as the outer height (H) / outer width (B) rectangularity ratio decreases and becoming zero when the value drops below about 1:2,5; the radius of curvature (Ra , Ri ) of the bore top and bottom wall (7) bearing against the wide sides (2), viewed in a vertical plane parallel with the longitudinal axis in the casting direction (arrow 4), is greater in the zone of the centre of the wide sides than at the bore side walls, the decrease in radius in the direction of the bore side walls being greater in proportion as the values of the rectangularity ratio becomes smaller ; each of the outer surfaces (2, 3) of the mouthpiece having, only over a portion of its longitudinal extension, a heat insulation (13) enclosing its periphery on all sides and an external, box-shaped metal covering (15, 15a) ; and the wide sides, which project beyond the narrow sides in thee casting direction at the mouthpiece outlet cross-section (9), have an arcuate closure edge of constant wall thickness.