GB729797A - Improvements in or relating to printing mechanism - Google Patents

Abstract

729,797. Printing-machines. ADDRESSOGRAPH-MULTIGRAPH GES. March 11, 1953 [April 19, 1952], No. 6758/53. Class 100( 2). Tripping-arrangements; rotary machines.- A printing-machine comprises means to cause the entire forme to be traversed by the impression roller by a continuous movement during each cycle of operation of the machine, means to move the impression roller into and out of rolling contact with the forme twice in each cycle, means to control one of said movements to cause the roller to coact with the same portion of the forme on each cycle, and means to control the other of said movements to cause the roller to coact with different areas of the forme on successive cycles. For printing normally the whole of the matter on a forme 15, Fig. 8, on a printing cylinder 10, sheets are fed between the cylinder and an impression roller 18 by means of a series of feed rollers 33 and a cam 38 which moves the rollers 33 into operation and retracts sheet stops 39 at regular intervals. The cylinder 10 carries an ink ribbon 42. The mechanism for selective printing is mounted in an auxiliary frame 50 and includes an impression roller 60 mounted on arms 75. Sheets are fed into a passage 47 and rest on stops 57. On every cycle, the stops 57 are withdrawn and feed rollers 61 are moved against the sheet to feed it to the roller 60, while the latter is pressed against the cylinder 10, so as to print the heading of the forme. The roller 60 is then retracted by a spring, while the sheet rests on stops 81. When the selected portion of the forme arrives in printing position, the stops 81 are retracted and the roller 60 moved forwards for printing. After the selected lines are printed, the roller 60 is withdrawn and the sheet drops on to a table. The movement of the stops 57, 81, the rollers 61 and the roller 60 are controlled by cams on a cam-shaft 74 driven from the cylinder 10, which is driven by a motor through a one-revolution clutch. The cam-shaft is driven intermittently so as to turn through one revolution in three stages, one for the "heading" printing, one for the "selected portion" printing, and one to return to its original position. The first movement of the cam-shaft is conveyed from a gear 95 rotatably mounted thereon and driven by the cylinder 10, to the shaft by means of a clutch controlled by a cam 103 through a cam follower 104 and levers 106, 113, 115. The third motion is conveyed similarly, but by means of a cam 185. The second motion is conveyed from a gear sector 130, Fig. 4, coaxial with the cam-shaft, to a clutch disc on the cam-shaft, the sector and disc forming a one-way clutch. The sector 130 is driven by a sector 135 rotatably mounted on the cylinder shaft 11. A ratchet-wheel 13 is adjustably secured on the cylinder 10 and carries a driving member at one point on its inner face which, when the cylinder has rotated through a certain angle, engages the sector 135 and advances it, there being a disengaging device on the sector so that the latter is only moved through a set angle. The portion of the forme which is printed from is thus determined by the angular position of the wheel 138 on the cylinder, and this is controlled by an escapement 146 comprising two pawls. The ratchet 138 is urged counter-clockwise by a spring 158. The arrangement is such that on each revolution of the cylinder a cam 157 acts on a roller 151 to actuate the pawls so as to advance the ratchet through one tooth, so that on each cycle the next adjacent portion of the forme is printed from that previously printed. Depressing a key 168 moves the cam 157 out of operation and causes repeat printing from the same portion of the forme. The key is latched in its depressed position, and the latch is normally released on each revolution by a projection 174, so that two successive sheets are automatically printed from each portion of the forme. A manually releasable detent is operable to retain the key depressed for continued repeat printing. A key 180 is provided which when depressed advances the ratchet one step. By using this key, any portion of the forme can be selected. The number of lines of the forme printed depends on the effective length of an elevation on one of the control cams on the shaft 74, and this may be adjusted by an angularly adjustable auxiliary cam. By rotating a shaft 108, Fig. 8, by a handle 109, the cam-shaft driving clutch can be disabled, and the whole selective mechanism rendered ineffective, the roller 18 then being used for normal printing. The forme may be a knurled sheet-metal foil, an offset or planographic forme, or any other suitable forme. The cam-shaft may act directly on the sheet, and constitute the impression roller, cam elevations producing the printing operation. Cylinder machines.-The cylinder 10 may be replaced by a reciprocating printing bed, the roller 60 and shaft 74 then being mounted in the machine frame above the bed, and the sector 135 replaced by a rack.