Reasons and solutions for rolling cracks of packaging steel strip

(1) Defect characteristics: scratches, scratches on the packaging steel strip, and metal tear marks during rolling. There are lateral fine cracks or metal peeling holes locally. The rolling cracks caused by scratches are short or continuous long strips, and the rolling cracks caused by scratches are short tadpole-like, cat's claw-shaped single or multiple rows.
　　(2) Cause
　　①The original scratches of the packaging steel strip materials.
　　②The packaging steel strip was scratched by sharp protrusions during pickling or shearing.
　　③The rolling mill guide plate is embedded with iron filings to scratch the packaging steel strip.
　　④The pickling steel coils are not tightly coiled or the rolling and uncoiling operations are not good. During tension rolling, the coils move between layers and scratch the surface.
　　(3) Prevention and elimination methods
　　① Prevent the surface of the raw material packaging steel strip from being scratched.
　　② Eliminate all kinds of hidden dangers that may cause scratches on the surface of the packaging steel strip in time.
　　③Check the guide plate frequently, and find that there is iron filings embedded in it and replace it in time.
　　④ Control the winding tension of the packaging steel strip and tighten the steel coil.
　　⑤ The unwinding operation must be stable and accurate and not reversed.
　　(4) Inspection and judgment
　　① Check with the naked eye.
　　②The high-quality board standard stipulates that the I-group board is not allowed to be cracked. The reverse side of the 2 groups of plates is allowed to have small cracks within the tolerance range not greater than the minimum thickness range. The two sides of the 10 groups of plates are allowed to have small cracks that are not greater than the minimum thickness within the half of the thickness tolerance, and small cracks that are not greater than the minimum thickness within the tolerance are allowed on the reverse side. There is no requirement for ordinary boards. It depends on the specific circumstances. The method for judging the cracks is: severe cracks with obvious cracks or pits caused by metal loss are judged as waste products. The cracks with light degree and small quantity can be judged as qualified products according to the standard. Those with only impressions but no cracks or meat loss can be judged as 2 sets of boards according to the provisions of the national standard high-quality boards. Those with slight cracks or meat loss can be judged as qualified products of 3 sets of boards or the ordinary version of the national standard according to the provisions of the national standard high quality.