Patent GB-191403795-A (GB)
Title: Improvements in or relating to Printing Presses.
Inventor: MORSE WILLIS STRICKLAND
IPC: B65H19/18
Filed: 1914-02-13
Granted: 1915-02-15
Abstract: 3795. Morse, W. S. Feb. 13. Feeding and registering webs.-The speed of rotation of the shaft of the web-supply roll of a printing-press is governed by means of a braking-device having an independent driving- device, which is normally inactive but is rendered active automatically by variations in the web tension by means of a movable member bearing against the web. The braking-device is preferably operated and controlled electrically, but may be controlled mechanically by means of gearing and a clutch which is operated by the movements of the member in contact with the web. Fig. 1 shows the invention applied to a double-deck printing-press, each deck having three supply rolls R and feeding a web to separate printing-couples. The shaft 11 of each roll is provided with a grooved brake wheel 12 engaged by brake shoes 13, 13<1> carried by levers 14, 14' pivotally connected at their lower ends to a bar 15 pivoted on a spindle 16 on the machine frame. The upper ends of the levers 14, 14<1> are connected by a spindle having right and left hand threads and provided with a hand-wheel 19, by turning which the normal pressure of the brake may be adjusted. The pivot connecting the lever 14 and bar 15 engages a slot in the bar 15 to permit a limited independent movement of the lever 14 under the action of an arm 21 of a bell-crank, the arm 21 engaging an extension 20 of the lever 14. The other arms 23 of the bell-cranks are connected to a link 24 operated by an electric motor 25 through gearing and linkage. Indicators 34 actuated by a connexion from the brake-actuating mechanism are provided to show that the mechanism is operating properly. The web 36 from the active roll on the upper deck passes over a spring-pressed compensating- roll 37, guide-rollers 41, and a tension-controlling roller 42 adjacent to the printing- couple. The roller 42 is carried by bell-cranks L, to one of which is pivoted a rod 51 mounted in guides 511, 512 and carrying a spring 50, bearing at one end against the guide 511 and connected at its other end to a slidable collar 52, the position of which may be adjusted by a handle 53 pivoted to the collar 52 and connected by a link 54 to an arm fixed to the rod 51. The handle is held in adjusted position by a spring pin 57 engaging holes in a member 56 pivoted to the arm 55. A modification of this spring-adjusting device is shown in connexion with the web 36<1> from the lower deck. The spring 57<1> bears against a loose collar 62 which can be moved along the rod 51 by means of a bar 61 carried by a rock-shaft 60, which is held in adjusted position by an arm 59 engaging holes 58 in the frame. The bell-crank L is connected to the arm 48 of a switch governing the motor 25. The switch comprises a fibre disk 65 secured to the spindle 49 of the arm 48 and carrying four insulated contact-strips 68, 69, 70, 71 engaged by five contacts comprising spring-pressed steel balls 86 mounted in casings 77 ... 81 secured to a stationary slate plate 74. The balls may be readily inserted in the casings by means of a cylindrical shell provided with a single side opening, the shell being placed between the casings and turned to bring the opening successively into alinement with the casings. The disk 65 is then secured to the spindle 49, and the shell withdrawn. The electrical connexions are shown in Fig. 7. The armature and field coils of the motor 25 are constantly energized; but each of the field magnets has a pair of coils wound so as normally to oppose each other, so that the motor is normallv at rest. When the web tension is above normal, the switch disk 65 is turned to connect the contacts 78, 79, and the field coils 143, 144 are more strongly energized than the coils 136, 139, and the motor is actuated to release the brakes 13, 13'. When the web tension is below normal, the contacts 77, 78 are connected and the motor is turned in the opposite direction by the action of the field coils 136, 139. A limit switch M is provided and adapted to be actuated by an arm 159 on the brake-actuating mechanism so as first to break the motor circuit and then close a second circuit to reverse the motor and bring it to normal position. The switch comprises contacts 150, 151 connected to the contacts 77, 79 respectively by wires 152, 153, which are also connected by wires 154, 157 to pivoted switch blades 155, 156 provided with forked arms 158 arranged in the path of the arm 159. To allow the normal tension of the web to be adjusted while the machine is running, the slate disk 74 carrying the contacts 77, 78, &c. is provided with a short rack 92 by which it may be turned in either direction. The rack is operated by a worm 94 turned in either direction by ratchetwheels 101, 102 and pawls 103, 104 operated by solenoids 107, 108, connected to switches 121, 122 under the control of the operator. The contacts 80, 81 are normally connected by the contact-strip 68 and are arranged in the circuit of a signal lamp 130, which is therefore normally lighted but is switched off when the switch disk 65 moves in either direction. A brake may be provided to bring the motor 25 to rest immediately the current is switched off. As shown in Fig. 9, the brake is applied to the face of the gear-wheel 27, which is driven bv the motor and comprises a brake shoe d carried by an arm b pivoted to a fixed arm a. The shoe d is pressed by a spring into contact with the wheel 27. A stop b<1> allows the arm b to swing through 180 degrees so that the initial movement of the motor in either direction is not retarded. When the brake shoes 13, 13<1> are being released, the load on the motor is less than when the brakes are being applied, and a greater breaking-force of the brake shoe d is necessary. This is effected by arranging the parts as shown in Fig. 9, so that the shoe d is further from the axis of the wheel 27 when the wheel is moving in one direction than when it is moving in the other.