GB782710A - Flying shear - Google Patents

Abstract

782,710. Automatic speed control systems. UNITED STATES STEEL CORPORATION. June 3, 1955 [Jan. 26, 1955], No. 16047/55. Class 38 (4). In a flying shear the relative speed of electric motors respectively driving the material to be cut and the cutters is maintained constant by automatically maintaining a fixed ratio between the voltages of separate generators supplying the motors, the drive to the cutters involving elliptical gearing associated with flywheels. In Fig. 1, steel strip S, fed by rolls 2 driven through gearing 10 by an electric motor 6, is cut into lengths by shears 4 driven through gearing 28 and 36 by an electric motor 26. Gearing 36 is elliptical and is associated with flywheels 50, 62 and 64 to even the load on motor 26. To maintain constant the relative speed of motors 6 and 26 and thereby obtain a constant length of cut strip, motor 6 is arranged to rotate the stator 100 of a potentiometer through gearing 68, shaft 70 and a synchronous electrical transmission 76, while motor 26 is arranged to rotate the arm 90 of the potentiometer through shaft 80, synchronous electrical transmission 84 and a clutch 92. Relative speed variations thus adjust the potentiometer and unbalance a bridge circuit formed with resistors 104, 106 so as to energize a field winding 108F of a generator 108 which excites a generator 122 to buck or boost the voltage applied from a generator 66 to motor 26 and thereby automatically correct the relative speed by adjustment of the speed of motor 26. The desired value of relative speed and hence length of strip is set by a handle 130 adjusting the ratio of gearing 68 and the excitation of generator 66 by differential potentiometers 158, 160 acting through an exciter generator 124. Strip length is indicated by a pointer 154 which is associated with handle 130 and co-operates with four scales corresponding to four selectable ratios of gearing 28. Handle 130 also adjusts the ratio of gearing 18 between a flywheel 20 and motor 6 so as to maintain a match between the kinetic energies of the drives to rolls 2 and shears 4. Part of the excitation of generator 124 is derived from a generator 22 supplying motor 6 so that if the rate of feed is varied by manual control of the excitation of generator 22, the speed of motor 26 is varied in a similar manner. U.S.A. Specification 2,180,202 is referred to.