COLD ROLLER AND COLD ROLLING METHOD
FIG5 is a graph showing an influence of a concentration of a rolling oil in a coolant upon a steel sheet temperature and a plate-out amount
The influence of the steel sheet temperature upon the plate-out property of the coolant is examined by variously changing the concentration of the rolling oil, the result of which is shown in FIG5. As seen from this figure, when the steel sheet temperature is not lower than 100°C, the plate-out amount of the rolling oil of each coolant having a different rolling oil concentration decreases as the steel sheet temperature increases. In order to ensure the given plate-out amount when the steel sheet temperature is high, therefore, it is preferable to jet the high-concentration coolant. For example, in order to ensure the plate-out amount of the rolling oil of not less than 50 mg/m2, the steel sheet temperature is necessary to be not higher than 120°C when the concentration of the rolling oil in the coolant is 3 mass%, while, the steel sheet temperature may be not higher than 180°C when the concentration of the rolling oil in the coolant is 10 mass%.
graph
50
not less than
5
be
10
not less than
20
preferably not less than
['3. The cold rolling mill according to claim 1 or 2, wherein the high-concentration coolant has a concentration of a rolling oil of not less than 10 mass%.']