METHOD FOR QUICK OPEN CONTROL IN DOWN COILER BY MORE ACCURATELY DETECTING TOP END OF STRIP TO CALCULATE POSITION THEREOF AND PROPERLY PERFORMING POSITION CONTROL OF UNIT ROLLS USING POSITION OF STRIP TOP END

摘要

PURPOSE: To provide a method for quick open control in down coiler to obtain rolling threadability and improve quality of strip by improving reliability of sensors for sensing position of the strip to accurately discriminate position of the strip during initial coiling of the strip and controlling open and close of unit rolls through improvement of sensor reliability. CONSTITUTION: In a method for quick open control by opening and closing a plural unit rolls(121-124) in a down coiler(130) for coiling a strip(101) passing through upper and lower pinch rolls(111,112), the method for quick open control in the down coiler comprises a step of sensing time at which a top end of the strip passes through a specific position by irradiating infrared light onto the surface of the strip being moved to the down coiler after passing through the upper and lower pinch rolls; a step of calculating position of the top end of the strip using a rotation speed of the pinch rolls and an elapsed time after sensing time at which a top end of the strip passes through a specific position; a first unit roll control step of starting coiling of the strip by controlling open and close of the plural unit rolls according to the top end of the strip; and a second unit roll control step of controlling open and close of the plural unit rolls using the sensed position of the top end of the strip after sensing position of the top end of the strip in a circumferential direction of the down coiler by irradiating infrared light onto the strip coiled on the down coiler.