A nozzle consisting of a pouring tube and a return cup extends down into a strand casting mold for pouring molten metal into it. The return cup is suspended in the mold at the lower end of the pouring tube and is submerged below the liquid level in the mold in a position to receive the metal issuing from the pouring tube and redirect it upwardly along the inside wall of the cup. The cup is dimensioned and located so that the eddies that are formed by the countercurrent flow of metal therein will lose their intensity before reaching the bottom and will die out before reaching the openings in the upper part of the cup through which the upwardly flowing metal escapes into the surrounding mold. The inside of the cup is large enough for its side wall and upper face of its bottom to be free from the eddies, while the outside of the cup is small enough to keep the metal that flows down around the outside of the cup from accelerating. The result is that the molten metal leaving the cup is substantially free of turbulence and flows in such a manner that the objectionable inclusion materials in the metal float up to the top of the molten body of metal in the mold around the cup instead of being carried down into the casting strand to contaminate the product upon solidification.
The invention relates to a casting tube for casting hot liquid metals and to a process for producing such casting tube. The casting tube comprises a casting tube head to be immersed below the casting level in the mould and having a closed bottom and at least one canal extending in lateral direction from the inner bore of the casting tube to which a vertically upwardly extending canal is joined whose length amounts to at least 4 cm. Such casting tube guarantees an excellent exclusion of non-metallic particles contained in the metal.
In continuous casting of metal in an open-ended mold through which the metal is advanced in a first direction while undergoing peripheral solidification, and to which molten metal is supplied by a shroud that opens beneath the metal level, use of a shroud having an axial nozzle and terminating in a well beyond the nozzle, with lateral discharge ports between the well and the nozzle oriented to discharge the supplied metal at an obtuse angle to the first direction, assists in reducing the incidence of entrapped inclusions. Injection of inert gas into the flow of molten metal within the shroud promotes transport of inclusions in the second direction within the mold. The shroud and/or inert gas injection may be employed in combination with the provision of electromagnetically produced metal circulation in the mold causing flow of molten metal, in a second direction opposite to the first direction, along the solid-liquid interface within the mold for preventing entrapment of inclusions at the interface.
The invention relates to a process for separating non-metallic inclusions from hot liquid metal and to a casting tube for carrying out such process. The method is employed in continuous casting, in which the metal is permitted to flow into a water-cooled mould, if desired via a tundish, whereupon the bar is drawn out of the mould and further cooled. In this process the metal, when flowing through the tundish and/or when entering the mould, is deflected under formation of at least one metal stream directed in upward direction. The length a of this metal stream amounts to from 3 to 30 cm and its speed v is adjusted to increase proportionally thereto in a range of at least 3.5 to 31 cm/sec up to maximally 17.5 to 45 cm/sec so that at the surface of the metal or of the slag or casting powder layer a wave is formed. When a and v are maintained within the mentioned range, a sufficient separation is guaranteed and the formation of turbulences tending to rupture the slag layer is avoided.
