CHROMATE TREATMENT OF GALVANIZED STEEL SHEET

PROBLEM TO BE SOLVED: To lessen roll maintenance and to improve chromate film quality by suppressing and preventing the surface contamination (the flocculation and adhesion of deposits from a chromate treating liquid) of wringer rolls which remove (drain) the excess adhesion components of the chromate treating liquid applied on a galvanized steel sheet surfaces in chromate treatment of the steel sheet. SOLUTION: Spray nozzles 4 are installed at the wringer rolls 3 and the chromate treating liquid of the same liquid composition as the liquid composition of the chromate treating liquid to be applied on the steel sheet S is sprayed to the rolls 3 to prevent the drying of the roll surfaces. The roll surfaces are held in a moist state at all times and the cooling and washing effects by spraying of the liquid are added thereto, by which the roll surfaces are kept in the clean state free from the deposits and floc. If the spraying of the liquid is executed by directing the spray nozzles 4 toward the upstream side peripheral surfaces of the wringer rolls 3, the spilling of the spraying liquid on the steel sheet surfaces does not occur and the liquid draining of the wringer rolls is not hindered.