Patent ID: 6524391
Filing Date: 2003-02-25
Classification: C23G

Abstract:
A method for automatically controlling a chemical cleaning stage of an aluminum strip cleaning line wherein a coil of aluminum strip having a speed and direction of travel is contacted with a chemical cleaning solution in a cleaning bath by spraying the cleaning solution onto top and bottom faces of the aluminum strip, by means of a plurality of spray nozzles mounted on transverse headers extending across the aluminum strip, as it passes through the bath,which method comprises providing a programmable logic controller; supplying to the controller a dwell time set point value for each coil of aluminum strip to be cleaned in the cleaning line, said set point value defining for standard conditions of chemical concentration and temperature the time the strip should be exposed to the chemical cleaning solution; measuring the temperature of the chemical cleaning solution in the bath and feeding to the controller a signal indicative of said temperature; measuring the concentration of the chemical solution in the bath and feeding to the controller a signal indicative of said concentration; calculating a temperature and chemical concentration compensated dwell time and, based on the compensated dwell time obtained, adjusting the dwell time of the cleaning solution spray on the aluminum strip such that the coil of aluminum strip being cleaned receives an approximately equal degree of cleaning from end to end, said dwell time being adjusted by selectively turning on or off flow of chemical cleaning solution to individual transverse headers.