| 摘要 |
<p>935,466. Electric control of rolling mills. WESTINGHOUSE ELECTRIC CORPORATION Jan. 8, 1962 [Feb. 10, 1961], No. 683/62. Class 38 (4). In a thickness control system a machine member whose position controls the thickness of a material is responsive to the difference between a stored error signal, above a predetermined limit, and a feedback signal representative of the change from a reference position of the member. As shown, a steel strip 1 is driven through mill rolls 2, the spacing of which is adjusted by screws 3 moved by a drive comprising a motor M and a generator G, having a field winding GF supplied from a controller E. Movement of the screws 3 is sensed by a synchro-transmitter ST sending a signal to a position sensing unit D, having an output proportional to change in the position of the screwdown rolls from the position last measured by the synchro-transmitter ST. At a distance from the rolls the thickness of the strip is measured by a gauge 4 which delivers a signal to an error detector T comparing actual thickness with a reference value. The difference is transmitted to an error sensing unit B which generates a gating signal when the error exceeds predetermined limits. The gating signal is applied to the position sensing unit D, the hold unit A and a gate H2. The gating signal (1) isolates the hold unit A from the error detector T, so that the last measured error is stored in the hold unit; (2) causes a position sensing unit to transmit a negative feedback signal to a summer S, proportional to change in position of the rolls from the position they occupied before the gate signal was applied and (3) allows the output of summer S, proportional to difference between thickness error and feedback signals, to be fed to the controller E. A counter E.M.F. device 5, responsive to the stopping of motor M at end of correction, applies a signal through a unit C, having a delay equal to the transport time of strip between rolls and gauge, to reset the sensing unit B, so that the gate H2 is closed, the hold unit A reconnected to device T and the position sensing unit D provided with a new reference corresponding to the new position of the rolls. The control of the system by the error sensing unit is arranged through logic circuit elements (see Fig. 4, not shown).</p> |
