GB866286A - Method and apparatus for automatic loop control - Google Patents

Abstract

866,286. Automatic loop control systems. NIEDERRHEINISCHE HUTTE A.G. Dec. 10, 1957 [Jan. 28, 1957], No. 38425/57. Class 38 (4). In an automatic loop control system for continuous wire rolling trains, variation in the product of the cross-section and rate of movement of the wire is detected by a loop of rolled wire rubbing on a contact strip of a potential divider, the tapped voltage controlling all subsequent roll-drives so as to maintain the loopsize constant. As shown, Fig. 2, a loop of wire 4 formed between a roll 1 and a roll 5 rubs on a contact strip of a potential divider 6<SP>1</SP> connected across a secondary 7, 8 of a transformer 9. The voltage between a tap 11 on the potential divider and the wire 4 is applied to a primary of a transformer 14. The voltage at the secondary of the transformer 14 is compared with a reference voltage, set by a potentiometer 15 across the primary of the transformer 9, in a comparator 16. The roll 5 is driven by a motor 29 controlled by a speed regulating unit 22 responsive to a signal from a tacho-generator 28 via the comparator 16 which modifies the control signal from the tacho-generator so as to maintain the loop size constant. The position of the loop for zero tapped voltage is controlled by tappings 12 on the transformer 9. The potential divider may comprise a tapped resistor, or a multi-tap transformer secondary. In a modification, the contact strip 6<SP>1</SP> and potential divider 15 are supplied from a directcurrent source and the comparator 16 compares two direct potentials. In another embodiment, Fig. 8, the rolls of a roll train are each driven by a motor 271 having a speed regulator 22 controlled by a tacho-generator 28 and a comparator 16 comparing a reference signal from a potential divider 15 with a signal, through a receiver 61, derived from a loop of wire 4 rubbing on a contact strip 6<SP>1</SP>. A transformer 14, feeding the loop signal to the receiver 61, has a tertiary winding 14<SP>1</SP> connected in series with all other windings 14<SP>1</SP> so that a signal is applied to terminals 47, 48 of a comparator 40 representative of the total variation of the loop from a predetermined size. The total variation signal through a full-wave rectifier 45 energizes control windings of transductors 43, 43<SP>1</SP> acting as a variable impedance shunt across a secondary 41<SP>11</SP> of a current transformer 41. The change in impedance of the current transformer with total variation in loop size varies the voltage applied across the potential dividers 15 so as to modify the speed of the rolls, as determined by the speed regulator 22, so as to maintain constant the product of wire-speed and crosssection. In a modification, the potential dividers are supplied with a direct potential, and the current transformer 41 replaced by a resistor.