Improvements in electrical control systems for machinery more particularly the flying shear control of metal coming from rolling mills

摘要

693,447. Electric control systems. METROPOLITAN-VICKERS ELECTRICAL CO., Ltd. April 19, 1951 [Sept. 4, 1950], No. 21782/50. Class 40 (i) [Also in Groups XXII and XXXVII]. In apparatus for shearing moving metal strip or the like into successive measured lengths, a tachometer generator, the output of which is integrated with respect to time, is driven at a speed proportional to that of the strip, and means are provided to initiate a shearing operation and to start a new integration when the magnitude of the integrated output reaches a predetermined value corresponding to the passage of a desired length of strip. The tachometer generator may be of the A.C. or D.C. type and driven by a measuring roll which is in the path of the strip, an over-run drive rotating the measuring roll so that when it is not engaged by the strip its peripheral speed is slightly less than strip-speed, and when it is engaged it will quickly attain the proper speed. As shown, the integrating device 1D has the signal from the tachometer generator applied to it through lines TG, the required length of strip being set on dials SL. When initially cropping a strip before shearing the first measured length, a flag switch FS is operated by the leading edge of the strip and subsequently causes, after a period which may be adjustable, the substantially coincident initiation of integrator means ID and operation of relay F1C, which starts, through contactor S, acceleration of the motor driving the shears. A contactor TS ensures that the device 1D stops integrating and resets a short time after the flag-switch opens as the end of the strip passes, the contactor F1C (or an alternative contactor 11C) being energised from the device 1D so as to be re-operated at the same period before the second cut as the signal to start integrating was in advance of the first cut. Means are provided for preventing the switch FS from initiating shear operation for cuts after the first, and for stopping false operation of contactor F1C or 11C. Shear-position interlocks are also provided. Two or more integrators may be so arranged that whilst one integrator is re-setting after measuring one length, the next length is being measured by the other integrator, the integrators continuing to function in this manner. Specification 665,380, [Group XXXVII], is referred to.