What are the causes of scratches on cold-rolled coils?
A: Sharp edges on parts in contact with the strip in pickling, rolling, and other units; malfunctioning pinch rolls and guide plates in the finishing line; and changes in strip speed during uncoiling or coiling, causing relative movement between layers-all these can cause scratches.
On which specifications of cold-rolled coils do wrinkles commonly occur? What are the causes?
A: They mostly occur on thin sheets less than 0.8mm thick. Causes include strip misalignment leading to unilateral stretching, poor sheet shape with large edge or center waviness, and uneven deformation due to improper straightening machine adjustment.
What is the impact of hot scratches on cold-rolled coils? How can they be avoided?
A: They damage the surface finish of the cold-rolled coil, affecting product appearance and subsequent processing performance. Prevention methods include preventing roll slippage, ensuring a stable and sufficient emulsion flow, and avoiding excessively high strip temperature that could cause the oil film to rupture.
What is the ideal temperature and humidity range for storing cold-rolled coils? A: The ideal storage environment should be maintained at a temperature of 5℃ - 35℃ and a relative humidity below 60%. This environment reduces condensation on the surface of cold-rolled coils, lowering the risk of corrosion.
What precautions should be taken when stacking cold-rolled coils?
A: Use dedicated steel coil pallets or anti-slip mats to avoid direct contact and compression of the coils; stack coils of different weights and sizes separately; the stacking height should generally not exceed 2 meters; label with batch number, specifications, and other information for easy management and allocation.