Patent GB-803962-A (GB)
Title: Arrangement for driving a winding device by means of a direct-current motor
IPC: B65H23/198
Filed: 1956-11-09
Abstract: 803,962. Automatic torque control systems. BROWN, BOVERI & CIE A.G. Nov. 9, 1956 [Nov. 10, 1955], No. 34338/56. Class 38 (4). [Also in Group XXXVII] A winding roller is driven by a D.C. motor 1 which is supplied from a main generator 3 in series with an additional generator 2, the voltages of the two generators being added together. A reference current is passed through control windings 11b, 12b and 13b, 14b of magnetic amplifiers 4, 5, the output of the amplifier 4 being applied to the field winding of the motor. As the diameter of the roll increases, the motor tends to take more current so that control windings 11a, 12a afford more opposition to the reference windings and the field of the motor is increased. As a result, the armature current of the motor remains substantially constant until the control range of the amplifier 4 is exceeded. Whilst the armature current is so maintained constant, the amplifier 5 undergoes no variation of its control currents and the voltage of the additional generator remains constant. However, when the control range of the amplifier 4 has been exceeded, the armature current can increase and the amplifier 5 is so controlled that the voltage of the additional amplifier is decreased whereby the torque developed by the motor remains constant. In addition to the reference windings 13b, 14b, the amplifier 5 has current-responsive control windings 13a, 14a which oppose the reference windings, and control windings 13c, 14c, which are responsive to the voltage of the additional generator and are also in opposition to the reference windings. The speed of the winding operation can be varied without variation of tension by adjustment of resistor 29 in the field circuit of the generator 3. This resistor is coupled to resistor 8 so that the ratio between the voltages of generators 2 and 3 remains constant for all operating speeds. In order to adapt the winder for operation with different materials, so entailing different motor currents, the windings 11a- 14a are sub-divided and the component windings are connectible in series or in parallel. In another arrangement, the magnetic amplifiers have additional control windings for compensating for frictional losses, these windings being energized in accordance with the voltage of the generator 3 and being connected to assist the reference windings. The difference between the voltage across the motor field winding and a constant voltage is supplied to other control windings of the magnetic amplifiers to compensate for losses due to weakening of the field. This difference voltage is also applied to two additional magnetic amplifiers through switches which are alternately actuated during acceleration and retardation operation of the winder. This enables constant tension to be maintained during - these operations, Fig. 2 (not shown). The additional magnetic amplifiers comprise short-circuited turns with tappings so that their time constants can be adjusted. A regulator for the control current proportional to the voltage ofthe additional generator may be coupled to the regulator for the reference current.