Operation of a multi-stand hot rolling mill

A method of operating a multi-stand hot rolling mill for rolling metal strip, comprising the steps of:

• rotating the rolls of the stands of said rolling mill at a relatively slow rate of speed so as to thread the head end of a hot metal workpiece through said rolling mill stands;
• determining and adjusting the rolling load at each of said stands during said threading operation so as to obtain the required desired output gauge of said strip and the required desired shape of said strip at the last stand, and to predetermine the rolling temperature at said last stand;
• rotating said rolls of said stands of said rolling mill at a speed faster than that of said threading speed for rolling said workpiece through said mill;
• providing coolant means for said workpiece at one or more interstand locations for cooling said workpiece during said rolling operation;
• determining the rolling load at each of the next stands downstream from said one or more interstand coolant application locations during said higher-speed rolling operation and comparing said high-speed rolling operation load values with said low-speed threading operation load values;
• and
• controlling the quantity of coolant applied to said workpiece at each of said coolant interstand locations as a function of, and in response to, the differential between said high-speed and low-speed load values such that said rolling load at each of said downstream stands during said rolling operation remains substantially the same as said rolling load at each of said stands as determined during said threading operation, and the rolling temperature at said last stand remains substantially at said predetermined temperature level.