| 摘要 |
PURPOSE:To control the crown of the hot rolled sheet to a specified value, and to reduce the frequency of exchange of the roll, by adjusting the flow rate of coolant for the roll to a specified value, in the rolling cycle from exchange of the work roll till next exchange. CONSTITUTION:At hot finish rolling pass, the flow rate of coolant for the roll is reduced at early stage of the rolling cycle, to an extent not to worsen the roll surface; then, the flow rate of coolant is increased in order to control the thermal crown Cb, for example, to a constant 200m, by gradually changing the flow rate with the progress of the rolling pass, so as to make the heat transmission coefficient (a) to be 500kcal/m<2>h deg.C at 20 minutes after the start of rolling pass, 1050kcal/m<2>h deg.C at 60 minutes, and 1200kcal/m<2>h deg.C at 90 minutes. As a result, the thermal crown of the roll can be held constant with the exception of the early stage, the constant sheet crown can be always obtained, the number of coils of hot rolled sheet per one rolling cycle is increased, and the rolling efficiency can be improved. |
