Reasons and solutions for indentation of packaging steel strip

1) Defect characteristics: scattered irregular or periodic deep pits or convex hulls appear on the surface of the packaging steel strip, the latter is also called roller print.
　　（2）Causes
　　① The welding seam of the packaging steel strip is too high, and the roller is not lifted in time during rolling, which causes the roller to stick.
　　②During the rolling operation, the roll sticking was caused due to the breakage of the packaging steel strip, traveling, folding, edge breakage, head and tail bumps on the roll surface, etc.
　　③The material of the roll is poor, and the surface hardness is low, causing sticking to the roll.
　　④The rolling mill is not clean, the iron shoulders of sludge, etc. are pressed into the packaging steel belt.
　　⑤Pickling, welding seam sticking slag and pressing into strip steel.
　　 (3) Prevention and elimination methods
　　①Keep the surface of the roller clean. When it is found that the roller is sticky, it can be polished with oil stone if it is slight, and the roller should be replaced if it is severe.
　　②It is forbidden to use rolls with unqualified rolling surface hardness.
　　③Keep the rolling mill clean.
　　④ After the welding seam is finished, the welding slag should be cleaned.
　　Check and judge
　　① Check with the naked eye and measure the depth or height with a dial gauge.
　　② No indentation is allowed on the surface of the first group of high-quality boards. The reverse side of the two groups of plates is allowed to have roll impressions within the tolerance range of the thickness of the steel plate that are not greater than the minimum thickness of the steel plate. The two sides of the three groups of plates are allowed to have roll impressions within the half of the thickness tolerance of the steel plate that are not greater than the minimum thickness of the packaging steel strip. The reverse side is allowed to have roll impressions within the tolerance range not greater than the minimum thickness of the packaging steel strip. The national standard stipulates that the indentation not more than half of the thickness tolerance is allowed in the ordinary plate. Ordinary board with line standard allows indentation not greater than 0.7 times the thickness tolerance.
　　③The local imprint can be eliminated by grinding.