Patent GB-367607-A (GB)
Title: Improvements in and relating to control systems for web-feeding apparatus
IPC: B41F33/18
Filed: 1931-03-27
Abstract: 367,607. Feeding webs; stopping- arrangements for printing machines. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Hepperlen, J. A.; 266, 4th Avenue, East Orange, 'New Jersey, U.S.A.) March 27, 1931, No. 9404. Convention date, March 31, 1930. [Classes 100 (i) and 100 (ii).] In a control system for web-feeding apparatus, such as printing-presses, means are provided for severing the web back of the plate or,type cylinders, or for stopping the press, or both, such means being controlled by light-sensitive means responsive to a function of the web such as. a break or interruption. The lightsensitive device 17 is situated on one side of the web 13 with a lamp 20 on the opposite side so that in the event of a break the lightsensitive device is actuated, whereupon the main motor 12 is stopped and the severing- device 22 is operated to cut the web between the rolls 14 and the press cylinders 10, thus preventing the broken end of the web from wrapping round the cylinders. Low and high speed motors 11, 12 are provided together with control buttons 38 .. 41. Depression of the inching-button 38 starts the motor 11, a circuit being completed from the main 24 through the button 38, a conducting piece 43, carried on a rotatable arm 30 but insulated therefrom, and a coil 27 to the main 25 ; the coil 27 attracts its armature 26 to complete the circuit of the motor 11. To start the press for a run, the fast button 39 is depressed, closing three circuits : (a) that of the pilot motor 31 by energizing the operating coil 48 of a switch 49 in the pilot motor circuit, the limit switch 47 being normally closed, whereby the arm 30 is turned in a counterclockwise direction ; (b) that of the operating coil 58 of switches 59, 60, 61, whereby the switches 59, 60 are closed'and switch 61. is opened. Switch 59 closes a circuit in parallel to the button 39 through the normally closed switches 41, 63, so that the button 39 may now be released ; (c) that of the motor 11 by means of the switch 60, the strip 43, and the coil 27, whereby the switch 26. is closed and the press starts at low speed. The continued rotation of the arm 30 causes the contact piece 43 to engage with the conducting segment 66, thus energizing the coil 29 which attracts its armature 28 and starts the main motor 12 at low speed, with the full resistance 32 in its armature circuit and the shunt field winding 34 fully energized. At the same time, the bar 43 moves off the segment 44, thus de-energizing the coil 27 and breaking the circuit of the motor 11. As the arm 30 rotates, the resistance 32 is gradually cut out and the field resistance 33 is cut in whereby the main motor is accelerated to full speed, when the arm 30 engages and opens the limit switch 47 to stop the pilot motor 31. To slow down the press, the button 40 is pressed to close a circuit through the limit switch 65, which closes when the arm 30 commences its rotation, thus energizing the coil 77, which attracts its armature 78 and closes the circuit of the pilot motor which now rotates in the reverse direction moving the arm 30 in a clockwise direction. The main motor slows down and when the pilot motor 31 stops consequent upon the release of the button 40, the press continues to operate at a speed corresponding to the position of the arm 30. To stop the press the button 41 is depressed, de-energizing the coils 29 or 27 to stop the motors 12 or 11, and also the coil 58 whereby the switch 61 is closed and completes the circuit of the coil 77 to start the pilot motor 31, so that the arm 30 may return to its normal position when the circuit is broken by the arm 30 engaging and opening the limit switch 65. The web-break detector operates to stop the press by energizing the coil 84 whereby the switch 82 is closed, thus energizing the coil 80 to attract its armature 63 whereby the circuit of the main motor 12 is broken. This only operates when the switch 83 is closed, i.e. when the motor 12 is driving the press. At the same time switch 85 is closed to complete the circuit of the coil 23 which operates the paper-severing device, the coil 23 being thus connected across the terminals of the main motor 12 and therefore only operated when this motor is driving the press. The coil 84 is in the output of the circuit of the electric discharge device 21 which is preferably of the grid-controlled arc-rectifier type. The grid is given a sufficient negative bias relative to the anode to prevent the starting of the arc by connecting' it as shown through a resistance 91 to the negative supply main 24, and the terminals of the photo-electric cell 17 are connected to the grid and filament, so that, when the web 13 breaks, the resistance of the cell 17 is greatly decreased on account of the illumination falling upon it, the grid voltage becomes much more positive, and the arc starts, thus energizing the coil 84, which operates as described above. To provide for different widths of web a number of lamps may be mounted behind the web and the cell is adjustable so as to be supported in any desired position. When a plurality of press units are being operated in parallel, each having its break detector, severing-device, and relay switches 82, 85, the switches 82 of the units will be connected in parallel with each other so that closure of any one due to a break in that particular unit will shut down the press.