Differential cooling system for control of thermal profile of work rolls in cold reversing mill

摘要

A differential cooling system for the control of the thermal profile of work rolls in a cold reversing mill of a steel plant comprises headers (9A and 9B) for applying coolant on a top back up roll (12A) optionally, headers (10A and 10B) for applying coolant on a top work roll (3A), headers (11A and 11B) for applying coolant on a bottom work roll (3B) at the entry side (E) and delivery side (D) respectively of each said roll. Each of the headers is provided with a row of nozzles spaced along the length thereof and directed towards the surface of the corresponding roll along the length thereof and with pipe lines (4A,4B,4C) with gate valves(15A,15B,15C) at the entry side and pipe lines (5A,5B,5C) with gate valves (16A,16B,16C) at the delivery side. The pipe lines are connected via pipe lines (17 and 18) respectively to a common pipe line (19) into which the coolant in the form of an emulsion of 2% by weight of oil in water prepared in a tank (1) having an agitator (2) is supplied by means of a centrifugal pump (3) via a pressure relief valve (4), pressure gauge (5), non-returnable valve (6), emulsion filter (7), and gate valve (8). The used coolant is collected in a pit (13) from which the same is returned to the tank (1) via a pipe (14) and an emulsion filter (19A). The nozzles have three-piece dovetail construction and are disposed along each header for producing a flat spray of coolant with the broad side lying along the length of each work roll. The inter-nozzle spacing on the headers is set to provide differential flow density of coolant in accordance with the temperature gradient built up in the rolls. The number of nozzles provided in each header for applying coolant on the top and bottom work rolls is reduced to 13 from 18 provided in the existing system. The pipe lines are of reduced length and number of bends compared to the existing system.