Abstract: Indentation defects (tongue marks) easily occur on the lower surface at the head during coiling of hot-rolled silicon steel coils, which are mostly distributed within 2～8m of the strip head, causing surface quality degradation, head scrapping and reduced yield. Combined with the coiling process characteristics of hot-rolled silicon steel, the formation mechanism of indentation was analyzed throughout the processes of head biting, multi-layer overlapping extrusion and stress solidification. The main inducing factors were clarified from strip head shape, equipment parameters, process system and roller stepping control. A complete set of prevention measures were proposed from process optimization, equipment adjustment, intelligent control and system matching. Field application shows that the defect rate decreases from 18.3% to 2.1% and the yield increases by 1.6% after optimization, which can provide engineering reference for stable coiling quality control of hot-rolled silicon steel.

Key words: hot-rolled silicon steel; coiling indentation; tongue mark; coiling process; wrapper roll; intelligent control