Continuous casting slab or priming slab is used as raw material, heated by step heating furnace, high pressure water descaling into roughing mill, roughing mill through cutting head, tail, and then into finishing mill, implementing computer-controlled rolling, laminar cooling (computer-controlled cooling rate) and winding machine after the final rolling, to become straight coil. The head and tail of the straight hair curl are often tongue and fishtail, the thickness and width accuracy are poor, and the edge often has defects such as wave shape, fold edge and tower shape. The coil weight is heavy, and the inner diameter of the steel coil is 760mm.