METHOD FOR CONTROLLING WIDTHWISE COATING THICKNESS DEVIATION IN CONTINUOUS HOT DIP GALVANIZING LINE

摘要

PURPOSE: A method for controlling widthwise coating thickness deviation of strip using an air knife equipped with variable nozzles in a continuous hot dip galvanizing line is provided. CONSTITUTION: The method for controlling widthwise coating thickness deviation in continuous hot dip galvanizing line comprises the steps of obtaining coating thickness deviation (Coj¬t) from arbitrary 't' measured strip widthwise coating thickness values (Cj¬t); obtaining coating thickness error (Ce¬t) using the obtained coating thickness deviation (Coj¬t); obtaining nozzle gap variation (ΔE¬(t+1)) using the obtained coating thickness error (Ce¬t); changing a nozzle gap as much as the obtained nozzle gap variation (ΔE¬(t+1)) by driving a nozzle gap driver; obtaining coating thickness deviation (Coj¬(T+1)) from (t+1)th measured strip widthwise coating thickness values (Cj¬(t+1)) after coating in the state that the nozzle gap is changed; obtaining coating thickness error (Ce¬(t+1)) using the obtained coating thickness deviation (Coj¬(t+1)); obtaining nozzle gap variation (ΔE¬(t+2)) using the obtained coating thickness error (Ce¬(t+1)); changing the nozzle gap as much as the obtained nozzle gap variation (ΔE¬(t+2)) by driving the nozzle gap driver; and repeating the steps of changing the nozzle gap after obtaining the coating thickness error (Ce¬(t+2)) and nozzle gap variation (ΔE¬(t+3)) after obtaining the coating thickness deviation (Coj¬(t+2)) from (t+2)th measured strip widthwise coating thickness values (Cj¬(t+2)) after coating in the state that the nozzle gap is changed.