METHOD AND DEVICE FOR HOT-DIP COATING A METAL STRAND

THE INVENTION RELATES TO A METHOD FOR HOT-DIP COATING A METAL STRAND (1), IN PARTICULAR A STEEL STRIP, IN WHICH THE METAL STRAND (1) IS FED VERTICALLY THROUGH A VESSEL (3) WHICH ACCOMMODATES THE MOLTEN COATING METAL (2), AND THROUGH A GUIDE CHANNEL (4) ARRANGED UPSTREAM, WHEREIN FOR RETENTION OF THE COATING METAL (2) IN THE VESSEL (3) AN ELECTROMAGNETIC FIELD IS GENERATED BY MEANS OF AT LEAST TWO INDUCTORS (5), ARRANGED ON BOTH SIDES OF THE METAL STRAND (1), IN THE REGION OF THE GUIDE CHANNEL (4), AND WHEREIN FOR STABILISHING THE METAL STRAND (1) IN A CENTRAL POSITION IN THE GUIDE CHANNEL (4)AN ELECTROMAGNETIC FIELD WHICH IS SUPERIMPOSED ON THE ELECTROMAGNETIC FIELD OF THE INDUCTORS (5) IS GENERATED BY MEANS OF AT LEAST TWO ADDITIONAL COILS (6) ARRANGED ON BOTH SIDES OF THE METAL STRAND (1). FOR IMPROVING THE EFFICIENCY OF CONTROLLING THE METAL STRAND IN THE GUIDE CHANNEL, THE INVENTION PROVIDES FOR STABILISATION OF THE CENTRAL POSITION OF THE METAL STRAND (1) IN THE GUIDE CHANNEL (4) TO TAKE PLACE BY THE FOLLOWING SEQUENCE OF STEPS IN A CLOSED CONTROL CIRCUIT: A) MEASURING THE POSITION ( S, S', S" ) OF THE METAL STRAND (1) IN THE GUIDE CHANNEL (4); B) MEASURING THE INDUCTION CURRENT ( I IND) IN THE INDUCTORS (5); C) MEASURING THE INDUCTION CURRENT ( 1KORR) IN THE ADDITIONAL COILS (6); AND D) ACTING ON THE INDUCTION CURRENT ( I KORR ) IN THE ADDITIONAL COILS (6), DEPENDING ON ALL THE PARAMETERS ( S, I IND, I KORR ) MEASURED IN THE STEPS A) TO C) ABOVE, IN ORDER TO KEEP THE METAL STRAND (1) IN A CENTRAL POSITION IN THE GUIDE CHANNEL (4). FUTHERMORE, THE INVENTION RELATES TO A DEVICE FOR HOT-DIP COATING A METAL STRAND.FIG.1