PURPOSE: To obtain a cold rolled thin steel sheet having a rectangular section which is equal in thickness in a transverse direction by combining adequately the sectional shape of a raw plate, the diameter of work rolls for rolling, the control of the deflection of the rolls and the selection of roll curves.
CONSTITUTION: A raw plate for cold rolling which has ≥0.985Hx/Hc (thickness at 15mm from width/thickness in the central part) is selected according to the level of the rectangular section of the thin cold rolled steel sheet required. The cold rolling of such raw plate is accomplished by using ≥1 among the work rolls having ≤500mm required diameter, the control of the deflection of the work rolls covering ≥50mm from the end of the plate, and the projecting curve of the required work rolls. Such roll diameter, roll deflection and roll flatness are selected by each of passes and stands according to the section level of the target thin steel sheet. The thin steel sheet having ≥0.975Hx/Hc and having the thickness equal in the transverse direction is obtd. by the above-mentioned method.
KURATA YOSHITERU
FUJITA TAMIO
