Patent GB-1252219-A (GB)
IPC: F27B9/20
Filed: 1970-07-10
Abstract: 1,252,219. Walking beam furnaces. SALEMBROSIUS Inc. 10 July, 1970 [10 July, 1969], No. 33608/70. Heading F4B. A control system for a walking beam furnace is provided whereby billets of a first size and desired centre to centre spacing are loaded at one end, and billets of a second size and desired centre to centre spacing already in the furnace are unloaded at the other, whilst the desired differing centre to centre spacings of the various billet sizes are maintained. In operation, the length of the forward stroke of the walking beam is selectively set to equal the second centre to centre spacing c, whereby one second sized billet is discharged by each such stroke. The forward stroke of a charging pusher is set to equal the desired first centre to centre spacing b. The magnitudes of these forward strokes are measured by respective pulse generating and counting means connected to the walking beam and pusher drives respectively, the values of the pulses being compared in a controlling comparator. When small billets are being charged after larger sized ones c # b, so the comparator after a first forward movement of first the beam and then the pusher of c and b respectively, controls the pusher to move forward a pusher distance of (c-b) to correctly space the first small billet behind the last large one. After a second forward movement of the walking beam a distance c and the pusher a distance b the comparator directs the pusher to move forward a further distance of 2 (c-b) to correctly position a second small sized billet behind the first. Similarly following the third and fourth forward strokes of the walking beam and the pusher respectively additional corrective pusher movements of 3 (c-b) and 4 (c-b) are made. This continues till n(c-b)#b, where n equals the number of forward strokes of the walking beam, when after the nth stroke and the necessary additional pusher corrective movement of n(c-b), the pusher is retracted and used to charge a further small billet before any further forward stroke of the walking beam, this time being given a necessary corrective additional movement of nc-(n+l)b. This determines the necessary corrective pusher movement for all following walking beam and pusher strokes until nc-(n+1)b#b, when the corrective stroke becomes nc-(n+2)b, and so forth. The corrective charging sequence is continued until the furnace is wholly filled with the small sized billets, after which the stroke of both the walking beam and the pusher are adjusted to b whereupon no corrective additional pusher movement will be necessary. Likewise when large sized billets are charged behind small sized ones (b # c), the controlling comparator, by when necessary stopping the pusher altogether, prevents the charging of a large billet until the walking beam has made sufficient forward strokes for the billet to be fully inserted in the furnace, and then instructs the pusher to make whatever additional movement is necessary to correctly position the first large sized billet, the necessary controlling sequence continuing until the furnace contains only the large sized billets, when the walking beam and pusher forward strokes are set at value b, so that a large billet may be charged at each stroke and continual correction of the length of the pusher stroke is no longer necessary.