GB414785A - Improvements in and relating to electrical control systems for controlling the thickness of strip material - Google Patents

Abstract

414,785. Regulating thickness of paper. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Winne, H. A. ; 1394, Dean Street, Schenectady, New York, U.S.A.) Feb. 18, 1933, No. 5092. Convention date, Feb. 18, 1932. [Class 96.] Variations in the thickness of a paper strip 21, from a predetermined value, causes gauging rollers 51, 55, to move an armature 43 between inductance coils 41, 42 so that the balance of a bridge formed by the coils 41, 42, and primary windings 62, 63 of a transformer 65, is disturbed, and an indicating relay 72 is energized from the secondary of the transformer 65 and moves in one or the other direction to energize through the appropriate relay 80, 81 one of two reversing relays 26, 27, which cause a motor 18 to make an adjustment of the roll 10, and restore the thickness of the material to the predetermined value. To compensate for the distance between the rolls and the gauging rollers, the motor 18 drives two segmental conducting discs 84, 85, the first of which, on the initial movement of the motor, maintains the circuit of the energized relay 80 or 81 independently of the relay 72, and the second energizes a relay 83 which opens the circuit of the relay 80 or 81 which passes through the relay 72. When the motor 18 has made one revolution, the disc 85 de-energizes the relay 83, and the disc 84 de-energizes the closed relay 80 or 81. The motor is, therefore, stopped and cannot be restarted until after a time interval required by the relay 83 to close its contacts. This time interval allows the material to pass a distance equal to that between the rolls and the gauging rollers so that if the adjustment made by one revolution of the motor 18 is insufficient as measured by the gauging rollers the operation can then be carried out again. If this compensation is not required a switch 100 is opened and a switch 82 closed. The time delay of the relay 83 may be adjusted in accordance with the speed of the material by energizing an auxiliary coil on the relay from a generator driven by the roll driving motor. In a modification of the means for compensating for the distance between the rolls and the gauging point, the closed reversing contactor maintains itself independently of the closed relay 80, 81, through the relay 83, and also energizes a relay which after a time closes its contacts to energize the relay 83, so that after the motor has run a certain time, it is stopped for a certain interval.