GB1290837A - - Google Patents

Abstract

1290837 Rolling GENERAL ELECTRIC CO 17 April 1970 [16 May 1969] 18424/70 Heading B3M A method of cooling metal strip in a rolling mill as the strip traverses a runout table 24 at varying velocities comprises determining by the use of a computer 40 (a) the residence times for each of contiguous sections of the strip on the runout table (b) the number of sprays 36 required to cool each of the contiguous sections from a finishing train temperature to a desired coiling temperature as a function of residence times and (c) altering the number of sprays applied to the strip in a sequence coinciding with the movement of the sections across the runout table so that each of the contiguous sections is subjected to the number of sprays determined to be required for that particular section. The head of the strip traverses the runout table 24 at a velocity V L until it is picked-up by a coiler 26 after which the velocity of the strip is accelerated to a speed V U . When the strip is detected by sensor 48, the number of sprays N L and N U required at the velocities V L and V U are determined from temperature curves as a function of a desired temperature drop. Since the control spray pattern is a function of the strip temperature at the end of finishing train 22 but is calculated before the strip reaches that point, the strip temperature is measured by pyrometer 42 so that knowing the thermal conditions, the temperature at the end of the finishing train is predicted. The desired coiling temperature is established by means of an auxiliary input 41. When the strip head reaches stand F5, a pulse tachometer 54 begins to monitor both strip velocity and the elapsed distance travelled by the strip head. Spray pattern and timing calculations are initiated for the remainder of the strip when the head end is sensed by thickness gauge 52. As the head end of each succeeding section of the strip is identified at stand F5 by the pulse tachometer 54, the residence time of that section is predicted from velocity time profiles. The length of the spray pattern and the timing of the action signals are calculated for the section at stand F5, based on the velocity profile of the strip as it then exits. When the tail end of the strip is detected by a load sensor 50, a mill slowing down procedure is initiated and final turn off time for the sprays which have been on for the last strip section are calculated at this time. As the tail end of the strip passes thickness gauge 52, the pulse tachometer 56 monitors the strip velocity as the tail end traverses the runout table.