Sinking roller scratches are a kind of surface defect of products in the production of continuous hot-dip galvanized coils. It not only directly affects the appearance of hot-dip galvanized products, but also affects the performance of hot-dip galvanized products. It will also reduce the corrosion resistance of hot-dip galvanized products, so that the products will first corrode at the scratches when they are used or transported, and lose the characteristics that hot-dip galvanized products should have;
In addition, hot-dip galvanized sheets with sinking roller scratches cannot be used as production substrates for color-coated sheets. In short, sinking roller scratches are very harmful to our hot-dip galvanizing production enterprises. Therefore, we must understand the mechanism of sinking roller scratches so that we can take the most effective measures to prevent and control the occurrence of sinking roller scratch defects.
So what is sinking roller scratches? How does it occur? Sinking roller scratches are caused by the inconsistent speeds of the strip and the sinking roller during the mutual movement between the strip and the sinking roller, and relative sliding occurs, and the surface of the strip is scratched by the sinking roller surface. Specifically, the strip enters the zinc pot from the nose of the annealing furnace for hot-dip galvanizing, and must pass through the sinking roller to turn out of the zinc pot. Since the sinking roller is in a special position in the zinc liquid, it is not conducive to installing a motor for transmission, so most of the sinking rollers are passive rollers, which rely entirely on the friction between the surface of the strip and the roller surface of the sinking roller to make the sinking roller and the strip move at the same speed; but sometimes due to the influence of mechanical equipment, production process control, the use of sinking rollers and other factors, the transmission friction between the strip and the sinking roller is insufficient, and the strip and the sinking roller slide relative to each other, resulting in the surface defect of the hot-dip galvanized product being scratched by the sinking roller.