Method for controlling forces on a strand as it solidifies

Claim 1

In a continuous-casting operation in which a partially solidified strand of indefinite length descends from the bottom of a mold and travels between series of rolls which engage opposite faces thereof; at least some of said rolls defining a curved path in which the strand bends, whereby its direction of travel becomes substantially horizontal; and a starter bar is connected to the leading end of said strand as the leading end emerges from the mold, but is disconnected therefrom at a location spaced below the mold; an improved method of controlling forces on said strand comprising: initially applying, through selected rolls of said series at a location preceding the location at which the starter bar is disconnected, a force restraining descent of said starter bar and said strand; subsequently using said selected rolls to apply a speedregulating tractive force to said strand as the leading end thereof advances through said curved path and a tractive force is required to propel the strand; initially operating other selected rolls of said series substantially as idlers, which other selected rolls have the capability of being driven and of applying auxiliary tractive forces to said strand; energizing the drive to the first of said other selected rolls nearest the mold when said speed-regulating tractive force reaches a predetermined maXimum; sequentially energizing the drives to the succeeding other selected rolls as the leading end of said strand advances farther along said curved path and the force on the immediately preceding other selected rolls in turn reaches a predetermined maximum; whereby lengthwise stresses in said strand are minimized through the operation.