GB1292845A - Predictive gauge control method and apparatus with adaptive plasticity determination for metal rolling mills - Google Patents

Abstract

1292845 Automatic control of rolling WESTINGHOUSE ELECTRIC CORP 3 Nov 1969 [12 Nov 1968] 53791/69 Heading G3R In a rolling mill, screwdown is automatically controlled to correct any difference between a desired thickness of rolled material and an actual thickness computed from roll force and screwdown position measurements and material plasticity computed from changes of roll force resulting from changes of screwdown position. In Fig.1, the thickness of a hot steel bar 14 is reduced at a series of rolling mill stands S 1 -S 7 (only S 1 & S 6 of which are shown) driven by motors 26 operating at successively higher speeds, the strip produced being wound up as a coil 16. Signals representing the thickness of strip emerging from each stand, computed by digital computers 38 from signals supplied by screwdown position detectors 32 and roll force detectors 34 control screwdown motors 28 to obtain a desired thickness, signals dependent on rate of screwdown being fed back from tachometers 29. Detectors 36, 44 supply signals corresponding to strip width and temperature to the computers 38 which are supplied at 40 with other data such as desired values, calculate mill constants and material plasticity values, and have redundancy and fail-safe features. Material plasticity is calculated from changes in roll force resulting from changes in screwdown position. Anticipatory screwdown correction, suitably delayed, is made at certain stands in dependence on conditions at one or more preceding stands. Compensation is provided for acceleration and deceleration and tail-end effects and computer 38 includes a section responding to and controlling variables of a preceding roughing mill (not shown). Selection from a number of different modes of operation, including manual, is made at a control station 43 and conditions are indicated and recorded at 46. The final thickness is maintained at a desired value by signals from an X-ray gauge 42 exerting a proportional plus integral control of screwdown at a number of preceding stands determined by the magnitude of any error. Tensions between stands are stabilized by signals from loop detectors 41 controlling the speeds of stand driving motors 26 through controllers 50, signals dependent on speed being fed back from tachometers 39.