The Hot Spray-system is an effective actuator for shape control especially in aluminium cold mills. By spraying heated oil onto the roll edges the thermal crown is compensated to such an extent that the tight edges no longer appear. By using the hot spray system, the danger of strip break-ages is reduced, the rolling velocity can be increased and a side-trimming of the material is no longer required. Lechler is a supplier of Hot Spray-systems, tail-or-made for each rolling mill or as an add-value unit for the Selectospray roll cooling systems.The heating up of the rolls is of major importance for the cold rolling of aluminium strip. The high reductions at the cold rolling process of aluminium strip lead to long periods of contact between rolls and aluminium strip, in turn this leads to very large material contact areas. Due to the high heat transfer coefficients and thermal conductivity coefficients of the aluminium materials, heat input from the strip into the rolls is significantly higher as compared to that of steel.
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