GB1452051A - Rolling of metal strips - Google Patents

Abstract

1452051 Rolling strip T SENDZIMIR 13 June 1975 [13 June 1974] 25425/75 Heading B3M [Also in Division G3] In rolling metal strip, lack of uniformity is detected by applying air pressure across the face of the strip, so that local variation in the deflection of the strip produced by the pressure results in local variation of that pressure, which variation is used to produce local variation in roll pressure so as to improve the strip flatness. In Fig. 6, the strip 1 is rolled under tension in a six-high mill, passing from an uncoiler (not shown) which applies back tension, over a deflecting roll 4, past open-topped pressure chambers 10 (one shown) extending in a row across the strip, and through wiper rolls 19 to the mill. The strip forms the upper surface of a pressure box 20 to which air is fed by pumps 21, the air passing past the rim of each chamber 10 into the chamber, and out through a calibrated valve 22, so that the pressure in each chamber is determined by the clearance between its rim and the strip. Lack of uniformity in the strip causes variation in its deflection from the pass line by the pressure differential across it, and hence variation in the clearance from the chamber rims. Figs. 3 and 4 show a work roll of the mill supported by two rows of backing bearings 8 each supported on a fixed shaft 9 through an eccentric member 6. Each pair of opposed eccentrics is rotatable by its own motor 7<SP>11</SP> through worm gears 7, 7<SP>1</SP>, to vary the pressure of the work roll along its length. The motors 7<SP>11</SP> are controlled by the pressures in the corresponding chambers 10 so as to tend to restore those pressures to a uniform value. Fig. 5 shows an embodiment in which the air pressure is applied to the strip by a row of chambers 10 on an adjustable beam 11 each chamber being unenclosed and supplied with air from its own positive displacement pump 13, all of which are driven synchronously. The chamber rim 10<SP>1</SP> is adjustable on a screw thread. The pressure in the chamber, dependent on the clearance between the rim and the strip 1, affects mercury columns 34<SP>1</SP>, 34<SP>11</SP> co-operating with adjustable electrodes 14<SP>1</SP>, 14<SP>11</SP> and flow smoothing needle 16 to control the respective motors 7<SP>11</SP>. A further mercury column 34a cooperates with adjustable electrodes 14a so that if the pressure in a chamber falls substantially, indicating a break in the edge of the strip, a wedge 23, Fig. 6, is immediately pushed by air cylinder 26 into the tapered gap between fixed beams 24, 24<SP>1</SP> to stop the strip and prevent damage to the mill. The signal on electrodes 14<SP>1</SP>, 14<SP>11</SP> may be sampled for half a second at ten second intervals, but that on electrode 14a is permanently operative. Where the pumps in, e.g. Fig. 5 are such as to deliver a pulsatory air supply, the strip vibrates. Similar equipment may be installed on the downstream side of the mill, and adjusted (e.g. by movement of roll 4 by screw 17) so that the vibrations of the strip on the two sides of the mill are of the same frequency, but out of phase, i.e. the upstream tension is a minimum when the downstream tension is a maximum. This permits a higher reduction in one pass, and also permits using a higher strip tension downstream of the mill than upstream, to offload the work roll drive.