GB915002A - Improvements relating to printing machines - Google Patents

Abstract

915,002. Printing-machines; etching; feeding sheets. ADDRESSOGRAPH-MULTIGRAPH CORPORATION. Sept. 7, 1960 [Jan. 14, 1960], No. 30836/60. Classes 100 (1) and 100 (2). In a rotary offset printing-machine, inking means, damping means, means for moving the printing and blanket cylinders into contact, blanket - cleaning means, and sheet - feeding means are actuated in predetermined sequence in response to movement of a control member from an initial position through at least one intermediate position to a final position, the control member being moved by electricallyactuated automatic control mechanism. The control-member is a shaft 262, Figs. 13 and 18, which is normally in position " 0 " and is rotatable in steps to positions " 1," " 2 " and " 3 " under an electrical control system including time delay relays, which energizes a solenoid 396 at predetermined times to cause a pawl 374 to step a ratchet wheel 379 in a direction determined by the time of energization with respect to the position of the pawl, which is continuously reciprocated from the printing- machine, but held out of engagement with the wheel when the solenoid is de-energized. In operation, a switch 38, Figs. 1 and 11, in a handle 37 is depressed, and a second switch 227 is closed when the handle is retracted after a plate-etch operation, thereby starting the machine drive motor. A relay solenoid is also thereby energized for the sheet feed vacuum pump, and the solenoid 396 is energized to move the shaft 262 to position " 1," which initiates application of the damping liquid. In the next machine cycle, the solenoid 396 is again energized to move the shaft 262 to position " 2," where it remains for several cycles, initiating application of the ink, and application of blanket-cleaning fluid, after which the blanket is allowed to dry. The solenoid 396 is then energized to move the shaft to position " 3," when the re-set coil of a counter 44 is deenergized to initiate counting, the master cylinder 32, Figs. 1 and 13, is moved into contact with the blanket cylinder, the vacuum valve solenoid for the sheet feed is energized, and a solenoid 133, Fig. 5, is energized to initiate the sheet-feeding mechanism after a delay for imaging of the blanket. When a predetermined number of sheets have been printed, the counter energizes the solenoid 396 three times by circuits through a timing switch so controlled that the shaft is moved to position " 2," when the blanket is run down, position " 1," when the sheet feed and inking are stopped, and position " 0," when the damping is stopped and after a delay the machine motor is stopped. By altering the position of switches on a panel 42, Fig. 1, the machine can be placed more or less under manual control, e.g. the shaft 262 can be controlled by a handle 43, the counter can be rendered inoperative and the machine be stopped by a switch 421, or the machine can be controlled by a sheet detector switch 103, Fig. 6. Etching.-Movement of the handle 37, Figs. 1 and 11, causes a transfer member 213 to swing out of contact with a sponge member in a metal receptacle 214 for etching liquid, and into contact with the lithographic master on the cylinder 32, while gears rotate the member 213 so as to bring the sponge-contacting face against the master. Return movement of the handle rotates a shaft carrying a cam which closes a sequence starting switch to initiate the operations referred to above, after the motor has been started by the closure of switches 38 and 227. Damping-apparatus.-Pivoted to lower fixed frame members are frame members 202, 203, Fig. 1, carrying the master cylinder. Pivoted to the members 202, 203 by a shaft 248, Fig. 13, are frame members 245 carrying the damping rollers, which include a forme roller 254. Movement of the shaft 262 swings the members 245 to bring the roller 254 against the cylinder 32, by means of a cam 264 and levers 255. Inking-apparatus.-Forme rollers 274, 275, Fig. 13, are moved on swinging bearings towards the cylinder 32 by manually rotating frames 272, 273, the whole assembly being carried on brackets 278, 279, whereby the forme rollers are brought into contact with the cylinder by sliding of the brackets under control of the cam 264 on the shaft 262. Blanket - cleaning - apparatus.-A blanket - cleaning roller 328, Fig. 15, in contact with a wick 331, is mounted on frame members 326 pivoted on a shaft 325 on main frame members 322, 323. The roller 328 is moved into contact with the blanket cylinder 300 by solenoids 344 acting through a link 347 and a lever 348 to swing the frame members 326. Impression adjustment.-Rotation of the shaft 262 causes eccentrically-mounted links to swing the frame members 202, 203 about their pivot 244 and bring the master cylinder 32 into contact with the blanket cylinder 300, the printing pressure being variable by adjusting the eccentrics. The blanket is thereby imaged before the sheet feed is operated. Feeding sheets.-Sheets are arranged in a stack 47, Fig. 4, on a table 51 vertically slidable to keep the top of the pile at the same level under the control of a bail 70, which moves up and down cyclically. In the upper part of the feed mechanism 34 is mounted a guide frame 83, 84, 85, Figs. 4 and 7, on which is mounted an auxiliary sheet shoot 49. The shoot 49 comprises L-shaped members 88, 89, Figs. 7 and 8, supporting an auxiliary stack 91 and secured to each other so as to allow adjustment of the shoot width. Mounted on the members 88, 89 are guides 94, 95 adjustable to alter the length of the shoot. A suction foot 63 is swingable about a shaft 66, along which it is adjustable, to convey sheets from the top of the stacks to feed rollers 61, 62, past a counterswitch 46, and on to a table 35 leading to the printing unit. If there are any sheets in the stack 91, they are fed first, and only when the stack 91 is empty are sheets fed from the stack 47. Sheets in the stack 91 are for special printing without operation of the counter 44, and when the stack 91 is empty a feeler 107, Fig. 6, actuates the switch 103 to render the counter operative. When the printing-machine is operative, it tends to reciprocate a bar 76, Fig. 5, to operate the bail, and to oscillate a cam 114 to operate the suction foot, but originally the cam is held against rotation by a pawl 143 and carries a stop 161 which holds the bar 76, so that the feed mechanism is inoperative until the pawl is released upon energization of the solenoid 133.