New generation of levelers for current requirements: Richtmaschinen und Bandanlagen
01.06.2006
New generation of levelers for current requirements
Sascha Becker
The requirements in the sheet metal industry have changed. There are two main developments: shortness of steel and the increasing use of high tensile material. Because of shortness of steel, sheet metal companies often do not get the quality they want. But they can achieve better quality if they use straighteners and levelers. The second development concerns mainly the automotive industry. To obtain flatness for the high tensile sheets, higher leveling forces and new concepts are needed.
Why do levelers increase the quality of sheet metal? To understand this connection, the leveling technology must be explained. Straighteners and Levelers are precision machines to correct defects in coils or plates. Defects in cold-rolled strips are coil set, crossbow, twist and edge camber. Coil set and crossbow are related defects resulting from coiling the strip. This causes a lengthwise streching of the inside surface relative to the outside surface of the uncoiled stock. The lenght wide streching causes a width wise contraction resulting in crossbows. Defects in wide strips are wavy edges, coil breaks and center buckles. Wavy edges and center buckles mostly occur in wide and thin strip. In the process of cold rolling the material, defections in the rolling mill cause some parts in the strip cross section to be reduced in thickness more than others. So, thinner portions of the strip are slightly longer than the thicker portions. This causes a "wavieness" in the longer areas.
Leveling technology removes material tensions ...