Patent ID: 8109320

Claim:
Method for continuous casting of preliminary steel sections having an I-shaped cross-section, the method comprising: providing a continuous mold comprising a mold cavity having a generally vertical strand traveling direction and a cross section composed of at least a web part and two flange parts; providing a stirring device consisting of one yoke, the yoke including a plurality of pole shoes situated on an inner side of the yoke and electromagnetic stirrer coils arranged in connection with the pole shoes to thereby provide a distribution of magnetic poles around the mold; wherein the yoke is a single closed yoke that surrounds the mold, the yoke has a rectangular frame with larger sides and smaller sides and eight pole shoes, three of the pole shoes being arranged on each of the larger sides of the rectangular frame in an arrangement in which a respective one of the three pole shoes faces each of the flange parts and one of the pole shoes faces the web part, and one of the pole shoes being arranged in a center area on each of the smaller sides of the rectangular frame facing a respective one of the flange parts, introducing molten steel substantially vertically into the mold cavity so as to form a partly solidified preliminary sectional strand having a molten crater therein; interconnecting said poles and providing said interconnected poles with 3-phase alternating current to form one of a plurality of different electromagnetic traveling fields in the molten crater having direction components transverse to the strand traveling direction and cause, as a result of the formation of the electromagnetic travelling field, the molten steel in the molten crater of the strand to flow from one portion of the strand to another, the different electromagnetic travelling fields including a linearly oriented electromagnetic field that causes molten steel in the molten crater of the strand to flow through the web part in a direction from one flange part toward the other flange part and a rotational electromagnetic field that causes molten steel in the molten crater of the strand to flow around one or both of the flange parts; the steps of interconnecting the poles and providing the poles with 3-phase alternating current comprising interconnecting all of the poles except for the poles on the smaller sides of the rectangular frame to cause linear flow of the molten steel in the molten crater of the strand through the web part in the direction from one flange part toward the other flange part or interconnecting all of the poles except for the poles facing the web part to cause rotational flow of the molten steel in the molten crater of the strand in each of the flange parts; and selecting the arrangement of the plurality of arrangements to interconnect said poles with the individual phase of the 3-phase current in accordance with casting parameters.