Patent GB-606668-A (GB)
Title: Automatic electrical speed control systems
IPC: H02P5/46
Filed: 1945-05-18
Abstract: 606,668. Printing-machines; feeding webs. SQUIRE, F. E. (Reliance Electric & Engineering Co.). May 18, 1945, No. 12582. [Classes 100(i) and 100(ii)] [Also in Groups XXXV and XXXVII] In a system in which material passes between two rotating elements driven by electric motors and a variable-speed drive is included between one of the electric motors and its associated rotating element, the latter operates, through a synchronous electrical transmission system, a differentially actuated regulator, also associated with the motor, driving the other rotating element, which varies the relative speed of the rotating elements to compensate for changes in the variable-speed drive. In a cloth printing machine, Fig. 1, the cloth to be printed, 21, is supplied from a reel 10 through first pull rolls 11, driven by a D.C. motor 51, to a scray device 12 on which the cloth accumulates to ensure continuous operation while joining each new roll. The scray device is an endless conveyer which may be driven by the weight of the cloth or by external means, and the cloth passes from it through second pull rolls 13, driven by a D.C. motor 52, and tension rolls 15, associated with a dynamo-electric machine 53, to the print. ing cylinder 16 which is driven through engraving rolls 17 from a D.C. motor 54. A dancer roll rheostat 14 controls motor 52 and hence cloth tension. From the printing cylinder the cloth passes over drying cylinders 18, driven by a D.C. motor 57, through folding rolls 19, driven by a D.C. motor 58, into a box 20 which is replaced at each join in the cloth. An idle roll 60 drives a synchronous electrical transmitter 59 connected to a synchronous receiver 62 which acts in opposition to a drive, through pulleys 66, from a motor 57 to adjust a differential regulator 63 controlling motor 54 to maintain the linear speed of the cloth on the printing cylinder equal to that of the cloth on the drying cylinders independently of change in size of the engraving rolls with different prints. Cloth tension is adjusted by a lever 67 controlling the ratio of pulleys 66. Back grey cloth 24, for ink absorption forms an endless strip passing under the cloth to be printed around the printing cylinder and over drying cylinders 34, driven by a D.C. motor 55. A dancer roll rheostat 32 controls motor 55 and hence back grey tension. Before the printing run the back grey is threaded from a supply roll 25 and joined to form the endless strip. At the end of the run it is cut and wound up on a batcher device 40 driven by a D.C. motor 56. Beneath the back grey around the printing cylinder is a continuous blanket 42. The following electrical controls are provided : (a) A " run slow " push button for initiating slow speed operation for threading during which motor 54 is supplied from a low-voltage " threading " generator. (b) A " run fast push-button for initiating normal printing operation during which motor 54 is supplied from a highvoltage " main " generator. (c) A " jogging " push-button for initiating slow speed operation as at (a) for a predetermined short period. (d) A manually operated rheostat, for adjusting the speed of operation under " run fast" conditions, controlling the setting of a motor-operated controller which is at its zero position under " run slow " conditions. (e) A " stop push button for stopping the equipment normally from the " run slow condition but which may, in emergency, . be operated during "run fast" whereupon alteration of resistances in the field and armature circuits of the motor of the motor-operated controller causes the latter to return rapidly to its zero position before the stop. When stopping all motors are dynamically braked. (f) A manually operated rheostat for controlling the speed of dynamo-electric machine 53 during " run slow " only when the motor-operated controller is in its zero position. At other positions of the motor operated controller this rheostat is short circuited and dynamo-electric machine 53 acts as a drag generator. (g) A manually operated rheostat for adjusting the armature current of motor 53, hence cloth tension. which may be operated automatically to maintain cloth tension constant. (h) Snap switches controlling the supply to motors 55 and 56 which can only be started under "run slow" conditions although, once started, they may continue to operate under "run fast conditions. (i) " Start " and " stop " push-buttons controlling the supply to motor 51 under any operating condition. A fixed resistance is momentarily inserted in series with this motor during starting. (j) Switches controlling the operation of electromagnetic starters for two threephase A.C. motors. One of these motors drives the " main D.C. generator which supplies motor 54 under "run fast" conditions, an auxiliary D.C. generator which supplies the remaining motors, and an exciter which supplies all machine fields and relays. The other A.C. motor drives the " threading D.C. generator and two buck and boost generators which co-operate with the auxiliary generator in supplying motor pairs 51, 52 and 55, 56 respectively. The operation of the starter for the second A.C. motor also connects the three-phase A.C. supply to synchronous transmitter 59 and receiver 62. Until this starter has operated the " run slow push button is ineffective.