Abstract
Temperature of bottom working roll of the first stand of hot strip finishing mill during rolling was measured by means of both thermocouples imbedded in the roll and hardness testing of quenched steel pieces plugged in roll surface. Instantaneous temperature change was detected by the former and lead to recorder through slip rings. The maximum temperature rise extremely close to surface was estimated by the latter.
Three zones differing in their temperature rise characteristics were found in the roll body. In zone I, 0 to 5mm from surface, temperature rise was instantaneous with steep gradient. It was sensitive to rolling variables for each strip. In zone II, 5 to 30mm, temperature rise was medium and moderately sensitive to both rolling variables and rolling number. In zone III, 30mm to center, temperature rose gradually with rolling number and reached a constant after 15 or more rollings.
Dependence of temperature rise on rolling variables was examined. Amount of cooling water was found most critical in determining the temperature and the reduction rate was the second, while interval of rolling was even less critical.
A rather abrupt rise of temperature was observed when reduction rate exceeded a certain value. This nonlinear characteristics were correlated with the increase in the heat of friction between roll and strip.
