AUTOMATIC CONTROL APPARATUS AND METHOD FOR MINIMIZING C-CURVATURE AND L-CURVATURE OF STRIP AT AIR KNIFE

摘要

PURPOSE: Automatic control apparatus and method for simultaneously correcting width curvature of strip transferred and pass line in upper part of hot dip coating pot are provided to reduce plating deviation by movably adjusting correction roll and deformation preventing roll in the hot dip coating pot to correct curvature and separation of pass line. CONSTITUTION: The automatic control apparatus comprises left and right driving motors(10a,10b) installed at left and right sides under air knives(6) of a pass line (P) through which a hot dip galvanized strip(1) passes; left and right screw shafts(12a,12b) fixed to rotation shaft of the left and right driving motors; left and right guide blocks(14a,14b) engaged with the left and right screw shafts in such a way that the left and right guide blocks are moved along the left and right screw shafts; and deformation preventing roll and correction roll(4) arranged in such a way that the deformation preventing roll and the correction roll are moved side to side with being fixed to the left and right guide blocks. The automatic control method comprises first process of measuring a separation amount between strip(1) and normal pass line (P) through a gap sensor(7) installed in an upper part of air knives(6); second process of moving correction roll(4) and deformation preventing roll side to side as rotating left and right driving motors(10a,10b) forwardly and reversely according to the separation amount; and third process of stopping driving of the left and right driving motors at that point after correcting the curvature to a set limit repetition point at which curvature is converged into zero point as repeating the second process several times.