GB1473159A - - Google Patents

Abstract

1473159 Stretch leveller drive HEAD WRIGHTSON & CO Ltd 4 Sept 1975 [9 Sept 1974] 39276/74 Heading B3E A drive mechanism for a continuous stretch leveller having a pair of bridles each including a main roll and other rolls, the main rolls being driven from a single motor, and each other roll from its own motor, includes for each bridle a torque meter measuring the torque applied to its main roll, and providing a signal used to control the energization of the motors driving the other rolls, to maintain the torques applied to the rolls of bridle in constant ratios. In the Figure, motor M drives roll 5 directly, and roll 4 through a differential gear the casing of which is driven through a variable speed gear-box by a separate motor, or motor M, or through an hydraulic pump/motor combination, so that the relative speed of rolls 4, 5 can be controlled to give a degree of stretch of 0 to 2%. The torques applied to the rolls are measured by meters T 1 , T 2 , and in the case of each roll of each bridle, the signal is sealed in an attenuator, e.g. V 2 for roll 2, and compared in comparator C 2 with a signal representing the current applied to motor M 2 by a thyristor device TM 2 , and hence representing the motor torque. An error signal operates the thyristor trigger circuit S2. The torques applied to rolls 1, 2, 3, 4 are thus controlled to be in the ratios 1 : 2 : 4 : 8. Similarly, the torques applied to rolls 5, 6, 7, 8 are controlled in the ratios 8 : 4 : 2 : 1. A correction signal Y may be applied during acceleration or deceleration of the apparatus to compensate for the acceleration or deceleration of the small motors M 1 ... M 8 being more rapid than that of motor M. An alternative control signal Z is provided for use in threading up, or for low speed operation when the torque meter outputs will be too small to be effective.