METHODS FOR MANUFACTURING COIL

摘要

Disclosed is a coil manufacturing method capable of calculating a defective index of inclusions based on an accuracy rate of a surface level and a rate of a changed casting speed in a slab manufacturing process. According to an aspect of the present invention, the coil manufacturing method comprises: a tapping step of manufacturing a slab by tapping ingot steel in a continuous casting mold; a measurement step of measuring a surface level of the ingot steel in a continuous casting mold at a preset time interval; a calculation step of calculating an accuracy rate of the surface level which is a rate between the entire numbers of the measured surface level and a number of measurement when the surface level is positioned within a preset first range, a rate of a changed casting speed which is a difference between the maximum casting speed and the minimum casting speed of the slab, and a defective index of inclusions defined as a function of the accuracy rate of the surface level and the rate of the changed casting speed; and a determination step of determining whether or not a rate of generating surface defects of the inclusions in a rolled coil manufactured from the slab with less than a first rolling thickness belongs to an allowable range by comparing the defective index of the inclusions and a preset value.