Method of flattening thin steel sheet - entails stretching heated sheet by bending when under tension and giving plastic elongation

摘要

The process improves the flatness of thin sheet steel and entails bending a heated tensioned sheet to bring about a plastic extension in the rolling direction, treatment being effected before the sheet is wound onto the roller gear. The temperature at which the extension occurs may be between 100 and 750 degrees C, extension being of the order of 0.2 to 2%. The extension may be effected by passing the sheet over one or more planing rollers, the angle subtended by the sheet at the roller being a function of the roller diameter the sheet thickness, the tensile stress, and the properties of the steel at the temperature concerned. The relevant machine uses a planing roller capable of deviating the sheet through 15 to 45 degrees, the roller being nominally bent at each end whilst having a diameter of 25 to 100 times sheet thickness.