GB467708A - Improvements in or relating to the cold rolling of strip metal - Google Patents

Abstract

467,708. Control of several motors. WILLIAMS, W. P. (American Rolling Mill Co.) Aug. 17, 1936, No. 22667. [Class 38 (iii)] [Also in Groups XXII and XXXV] In cold rolling a strip in a series of rolls M with tensioners T between each mill or group of mills, the tensioners T have a constant pull and are coupled to the rheostats of the corresponding mill motors or to puller motors so that there is a constant positive difference between the tension in the strip on the outgoing side and the tension of an incoming side of the mill or group of mills. A puller may be located beyond the final mill which exerts a tension not less than the sum of all the differences in tension on each side of each individual mill or group. The strip is comprised of shorter strips joined end to end by a welder 51, and trimmed by a flash cutter, and forms a free loop 53 before back tension is applied as it proceeds to the mill. At the exit the strip is sheared into length and coiled up. Each strip tensioner T comprises three rollers 12, 13, 14, Fig. 6, the roller 14 being urged up into the loop of the strip by an adjustable weight or an adjustable pressure hydraulic cylinder 19 to take up any slack to maintain the tension. As the roller 14 moves up or down, a cable 27, Fig. 6, attached at one end thereto rotates a sprocket 36, Fig. 8, which chain drives a rheostat 45 so controlling the mill motor or the motor of the strip puller. The sprocket 36 has a lost motion gap for the drive pin 35. A hand wheel 43 can also be operated to declutch the chain drive 39 and operate the rheostat as desired. To thread the strip through the mill the cable 27 is slackened off to lower the tensioning roller 14 to allow the strip to be threaded through. Fig. 10 shows the electrical drive controls in which a motor G drives a generator H supplying current to all the mill motors A<1>, B<1>, &c. and to the motor F<1> of the strip puller P. The operator at 40 operates hand wheel 21 of rheostat 343 of motor F<1> and so controls the tension pull and control of motor F<1> also in turn controls the speed of all the other motors in the train automatically through the action of the tension take-up devices T. By opening a switch 345 the trip breaker 902 stops the puller motor F<1>. If the strip breaks, e.g. at the switch SS3 it trips the circuit-breaker 502 of mill motor A<1> and also through leads 314 trips breaker 602 stopping the motor B<1> and so on so that all mill rolls preceding the break stop. The operator 40, however, operating switch 1100 closes electromagnetic circuit to hold closed the switches SS2 &c. while the mill is being threaded. The operator adjusts a rheostat 1001 to control the exciter K which controls the voltage applied by the generator H to all the mill motors A<1> &c. while each static tensioner T superimposes an individual control of the speed of the corresponding mill motor. An indicator light 403 is connected with the main breaker 401. Specification 6048/11, [Class 38 (iii)], is referred to.