Patent GB-1000595-A (GB)
Title: Improvements in or relating to rolling
Inventor: SHIPP PETER JAMES
IPC: B21B37/46
Filed: 1963-02-15
Abstract: 1,000,595. Control of motors. BRITISH IRON & STEEL RESEARCH ASSOCIATION. Feb. 14, 1964 [Feb. 15, 1963], No. 6221/63. Heading H2J. In a reversing mill, the mill rolls are braked to decelerate a work-piece before exit from the mill so that the workpiece has a predetermined exit speed on emerging from the rolls. The workpiece is decelerated after exit from the mill and accelerated for re-entry, during which time the roll spacing is adjusted. These operations are substantially of the same duration, a factor in determining the duration of the reversing operation being the exit speed. Detectors A, B are disposed adjacent to the workpiece path on one side of the mill with known separation from each other and from the roll-gap. The detectors may be heat-sensitive devices or photo-cells for indicating passage of the trailing end of the workpiece. Signals are thus obtained representing the angular rotation of the rolls after the end passes detector A, these signals being compared with signals representing actual rotation to indicate the remaining roll rotation before the end reaches the gap. The angle through which the rolls will turn after a braking signal is given is calculated as a function of mill speed, the braking distance in terms of roll angle being stored. When this angle is equal to the instantaneous roll angle displacement from its calculated end point, the braking signal is given. As shown, detectors A-H and A<SP>1</SP>-H<SP>1</SP> for both sides of the mill are provided. When the workpiece enters the mill, a load cell 11 generates a signal which, together with the signal from detector A or A<SP>1</SP>, operates circuit 12 of switch 13 to connect the approtiriate range of detectors into the control system. Circuit 14 is responsive to detector D or D<SP>1</SP> to provide a signal on line 15 or 16 denoting long or short workpieces. An indicator 17 applies a signal representing mill roll angular position to gates 18, 19 which are controlled by gates 20, 21 producing successive pulse signals as the associated detectors sense the trailing end of the workpiece. Gates 20, 21 are respectively opened by signals on lines 15, 16. Gate 18 is opened by the first pulse from gate 20, 21, and closed by the second pulse, while gate 19 is opened by the second pulse. The output signal from gate 18, represents the roll angle turned through during travel of the trailing end of the workpiece between the first two detectors, the signal from gate 19 representing the angle turned following generation of the second pulse. The signal from gate 18 is applied to multiplier 22, whose factor is determined by the length of the workpiece, to produce a signal representing the roll angle to turn between the time of the second pulse and ejection of the workpiece. Application of signals from gate 19 and multiplier 22 to comparator 23 provides an output representing the roll angle to turn before ejection. In the case of short workpieces, which are rolled at a base speed, the braking angle is pre-calculated and stored in device 24, the signal therefrom being applied, together with the signal from comparator 23, to comparator 26, which indicates the angle to turn before braking. The output from comparator 26 is applied to zero detector 27 generating a signal to energize the braking system associated with roll motor 28. In the case of long workpieces, the signal on line 15 is applied to motor 28 to effect acceleration. A signal from roll speed indicator 29 is applied to function generator 30 producing a signal representing the braking angle for the roll speed. This signal is fed to comparator 26. A timed screw-down system comprises means 31 producing a signal representing the required adjustment, generator 32 producing a signal representing the time for adjustment, a timer 33 initiated in response to the load cell when the workpiece is ejected, screw-down control gear 34, and screw-down motor 35. The exit speed is varied in accordance with the screw-down period by generator 36 associated with generator 30 providing a signal representing the difference between the actual and desired exit speeds to comparator 26. Workpiece reversal is effected by control gear 37 associated with load cell 11. Lateral manipulation of the workpiece is effected by squaring heads driven by motors on different sides of the mill. When a workpiece leaves the mill, the heads between which the workpiece is lying are closed to grip and then reversed for a predetermined time to provide small edge spacing. The other heads are operated to provide a larger edge clearance.