GB1302040A - - Google Patents

Abstract

1302040 Continuous casting USS ENGS & CONSULTANTS Inc 30 Dec 1969 [31 Dec 1968] 63373/69 Heading B3F [Also in Division C7] In a method of controlling heat transfer to or from an elongated object (such as a steel strip to be heated or a cast strand to be cooled) passing continuously from one point to a station where heat is transferred, for each of a number of increments of length, the time to travel from the point to the station is measured and the heat transferred at the station to or from each said increment is controlled according to the elapsed time for the increment to obtain a desired heat transfer rate. A continuous strand C is drawn for cooling, past spray stations 8, 10 by withdrawal rolls 4 and, as each increment 1-36 (say six inches) of length passes through the rolls, a generator 16 passes a signal to a digital computer 20 having 36 memory cells, cell 1 corresponding at any time to the increment leaving the mould 2 at that time and cell 36 to the increment leaving the rolls. If the strand speed is 72 inches/min., i.e. twelve increments/min., a time of 5 sees. for each increment is impressed temporarily and successively on each cell, i.e. as each relates to the position of the corresponding increment. If the speed is then halved, 10 sec. times are so impressed and follow the 5 sec. impressions in their progression down the computer memory section 24. When the leading end of the strand C, i.e. increment 1, reaches the middle of spray station 8, the computer calculates the time elapsed since it left the mould, i.e. the sum, viz. 75 sees., of the times in cells 1-15 at that moment. A valve 12 will then be controlled by the computer accordingly. Similarly, when the strand end reaches the middle of spray station 10, a valve 14 is controlled according to the time total, 135 sees., of the cells 1-23. The cooling rate may be modified by the surface temperature of the casting, detected by sensors 28, or by the time the metal resides in the mould 2 before leaving it. Alternatively, memory cell 1 may record the total elapsed time since the start of withdrawal from the mould 2, with the contents of each other cell, as before, being replaced by the contents of the next preceding cell at each signal from the generator 16. In another embodiment, with a single spray station (34), a preset counter (30) accumulates the generator pulses and passes on a signal when the number of pulses represents a desired strand increment, e.g. six inches.