Coil leveling is a fascinating process that plays a crucial role in the production and processing of steel. It involves the manipulation of metal coils to reduce or eliminate distortion before further processing or fabrication. The process is based on the assumption that the flatness of the coil will directly translate to a distortion-free end product.Get more news about coil leveling,you can vist our website!
Steel production and processing are continuous operations where the last step is coiling. Steelmakers and processors use tension when coiling to avoid producing "soft" or collapsing coils. Coiling induces tensile and compressive stresses into the strip, and these stresses can contribute to blank or part distortion in subsequent processes.
Coil shape imperfections like coil set and crossbow can occur due to these stresses. Coil set is a bow condition parallel with the rolling direction, and curves downward in the same direction as the upper outside lap of an overwound coil. Here, the top surface of the coil or strip is stretched more than the bottom surface, and typically becomes more severe as the coil is processed and the lap diameter decreases.
Crossbow is a bow condition perpendicular to the rolling direction, and curves downward in the same direction as the upper outside lap of an overwound coil, with the center portion of the sheet raised a measurable amount above the sheet edges.
The first operation when unwinding a coil is some type of shape correction to ensure flatness before further processing. There are two main types of equipment used to create a flat coil - a straightener and a precision leveler. While these two types of equipment are similar, a precision leveler has additional capabilities.
Both bend the coil back and forth over a series of work rolls to alternately stretch and compress the upper and lower surfaces. Critical equipment parameters include roll diameter, roll spacing, backup rolls, roll material type, gear design, backup rolls, overall system rigidity, and power requirements.
Straighteners and levelers have a series of rolls that progressively flex the strip to remove the residual stresses. Each successive roll pair has an adjustable gap to deform the sheet to a targeted amount with the goal of resulting in a flat coil once the steel passes through all the rolls.
Leveling at-risk coils with repeated cycles of bending and unbending may be an effective way to minimize stretcher strains or fluting. However, process control is critical, since excessive leveling work hardens the coil and results in increased strength and reduced ductility.
In conclusion, coil leveling is a complex process that requires a deep understanding of the properties of the metal being processed, the equipment being used, and the desired end product. Despite its challenges, it remains a vital step in the production of high-quality, distortion-free metal products.
