Patent GB-449877-A (GB)
Title: Improvements in or relation to electric drives and control systems for rolling mills
IPC: B21B37/46
Filed: 1935-01-03
Abstract: 449,877. Automatic control systems. WESTINGHOUSE ELECTRIC & MANUFACTURING CO., East Pittsburg, U.S.A.- (Assignees of Kenyon, A. F. ; 1330, Woodlawn Avenue, and Cook, W. G. ; 200, Marion Avenue, both in Wilkinsburg, Pennsylvania, U.S.A.) Jan. 3, 1935, No. 260. Convention date, Jan. 3, 1934. [Class 38 (iv)] [See also Group XXXVII] Strip tension.-A reversible rolling-mill drive and control system comprises two reels 11, 12, Fig. 1, upon or from which the strip material, being worked upon by means 10 positioned intermediate the said reels, is adapted to be wound or unwound, and dynamo-electric machines associated with each of said reels, the arrangement being such that for both directions of movement of the strip material, at any moment, the dynamo-electric machine associated with the winding reel is connected to a power source 19 to operate as a motor, and the machine associated with the unwinding reel operates as a generator returning energy to the power source through a series-connected booster 22. Reducing rolls 10 operating on the strip are driven by a motor 15 supplied from the generator 19. The tension of the strip is maintained by regulators 44, 45, Figs. 2 and 3, the regulator 44 being used always on the delivery side of the mill and having a coil 49 energized across a resistance 67 or 68 in the armature circuit of the delivery reel motor, and contacts 51 controlling resistances 52-55 in the field circuit of a booster generator 39 or 40, Fig. 4, which controls the field of the delivery motor. Similarly, the regulator 45 which is always used on the entry side of the mill, has a winding 59 connected across a resistance 26 in the armature circuit of the booster generator 22, and contacts 61 controlling resistances 62-65 in the field circuit of a booster generator 39 or 40 which controls the field of the entry motor. The voltage of the supply generator 19 is increased and decreased to accelerate and decelerate the mill by means of a resistance controller 93, Fig. 3, operated by a pilot motor 94 controlled by reversing contactors 98, 99, and limit switches 101, 102. In order that the regulators 44, 45 shall maintain the tension during acceleration and deceleration, resistances 69, 69a, in the circuits of their coils 49 and 59, are adjusted by relays 74-77 under the control of compensating relays 78, 79, operated by closure of contacts on the pilot motor reversing contactors 98, 99. This permits an increase of the current generated by the entry motor, and a decrease of that taken by the delivery motor during deceleration, and an opposite control during acceleration, whereby the inertia effects are compensated. The mill may be operated either in a slow or fast speed range determined by the position of a master switch 116 or 117, Fig. 4 (one on either side of the mill) which controls slow and fast relays 87, 88. These relays control a resistance 111 in a main field winding 23 of the booster generator 22 which field is reversed with change in the direction of the pass, and a resistance 294 in the field 295 of the mill motor. They also select appropriate regulator adjusting relays 74, 77, for operation to adjust the regulator setting for slow or fast operating conditions, and control armature and field resistances 302, 304 for the controller pilot motor 94. Furthermore, they select appropriate resistances in the field circuits of the reel motors and in the auxiliary field 24 of the booster generator 22. This auxiliary field is rendered practically ineffective when the main generator voltage has built up by means of a relay 321 which inserts a resistance 318. The speed range selected may be changed only when the mill is stopped, and, after the speed range is selected, control is effected by one of two master controllers (one on either side of the mill). the particular controller employed being determined by the direction of the pass. The master controllers have " stop," " slow," raise," and " hold " positions corresponding to the stopped condition of the mill (with the strip under tension), a reduction of the speed thereof, an increase of speed, and constant speed. Reel and mill master switches control the reel and mill machines individually for setting up the mill. "Inch," ''tension," and " release tension " switches are also provided, one set on either side of the mill. The direction of the pass is determined by a pass-selector master switch 114.