ROLLING MILL CONTROL SYSTEM

摘要

1301489 Automatic control of rolling ALCAN RESEARCH & DEVELOPMENT Ltd 29 Dec 1969 [3 Jan 1969] 63145/69 Heading G3R In a system in which off-flatness or thickness of material being rolled is detected at a number of points across its width for on/off control of the heating or cooling of corresponding zones across the width of the rolls to maintain the material of uniform section, the highest and lowest deviations are detected in the "off" zones and "on" zones and utilized to determine changeover between the "on" and "off" conditions. In Fig. 1, strip 35 is rolled between rolls 16, 18 associated with back-up rolls 12 to 14 respectively. A screwdown motor 23 applies pressure to the rolls and hydraulic jacks 28, 30, 31 apply forces between the several rolls as shown. The load on the rolls, detected by load cells 60, automatically controls the hydraulic jacks through a system not shown, and the difference between the hydraulic pressures applied to jacks 28 and jacks 30, 31 is detected by an electrical comparator 90. If this difference is such as to cause excessive bending of the rolls, a logic circuit 84 is influenced to so control valves V 1 -V n supplying oil to jets 78 and 80, 1-n, that appropriate zones of the rolls outside the width of the strip are cooled to reduce the difference. These outside zones are selected by a unit 96 which is set in dependence on the width of the strip. On leaving the rolls, the strip passes to a transducer roll 70 which detects tension in the strip at a plurality of zones across its width and supplies corresponding electrical signals through slip rings 72, 1-n, and gates 1-n to logic circuits 98, 100, 84 so that roll zones within the width of the strip are cooled or not as necessary to equalize the tensions and hence flatness and thickness across the width of the strip. Maximum and minimum tensions in the zones which are being cooled ("on" zones) are determined by logic circuit 98 and maximum and minimum tensions in the zones which are not being cooled ("off" zones) are determined by logic circuit 100. Then, if the highest tension in the "on" zones is greater than the lowest tension in the "off" zones and the range of tensions in the "off" zones is greater than the range in the "on" zones or the numbers of "off" and "on" zones are in a predetermined relationship, cooling is changed from "off" to "on" in that "off" zone having the lowest tension or vice versa provided that the difference between the highest and lowest tension exceeds a predetermined value and strip speed exceeds a predetermined value or a predetermined time has elapsed since starting up as determined by a unit 114. Manual over-riding control of zone cooling is provided. Suitable transistor logic circuits are described.