GB621739A - Printing machine - Google Patents

Abstract

621,739. Rotary offset machines. ADDRESSOGRAPH-MULTIGRAPH CORPORATION. Nov. 6, 1945, No. 29595. Convention date, Jan. 17. [Class 100 (ii)] A cylinder 20 carries a master sheet 22 transferring to an offset roller 30 coacting with an impression roller 40 carried by a shaft 41 eccentrically mounted in a carrier 42 spring-pressed towards the roller 30, a second spring 136 being provided for turning the shaft 41 in its carrier 42 to separate the roller 40 from the roller 30, rotation of the shaft being normally restrained by a latch 132 controlled by a paper-detector, and an adjustable stop 49 being provided which is set so as to limit the movement of the carrier, thereby controlling the printing pressure, and also to ensure that on release of the latch the rollers 40 and 30 are separated. The carrier 42 is in the form of a yoke, and two stops 49 are provided each consisting of a nut on a screw 48 anchored to the yoke at 45. The nuts are pressed towards a cross-bar 46 by springs 44, the tension of which is adjustable. The spring 136 acts on a rod 135 connected to a plate 130 which is fixed to the shaft 41 and has a shoulder 131 engaging the latch 132, whereby the plate and therefore the roller 40 are held in normal positions. A detector 141 tests for the presence of sheets between feed rollers 101, 102 and acts through a lever 142 and link 144 to release the latch 132 if no sheet is present. The plate 130 is returned to normal position after a release, by a pawl 148 carried by a rocking arm 72; the pawl also turns the plate slightly each cycle of operation of the machine to relieve the pressure on the latch 132. The Specification also describes mechanisms (a) for controlling the movement of the offset roller and the feed of sheets, and (b) for applying ink and ink-repellent, forming the subject-matter of Specifications 621,774 and 621,775 respectively. A master sheet may be attached to the cylinder 20 as in Specification 499,809, ink and ink-repellent ductor rollers may be actuated as in Specification 526,324, a hand-lever for controlling the application of ink, repellent, or both, may be provided as in Specification 499,810, and the offset roller may have a sheet-gripper to which sheets are guided, as in Specification 499,800. Inking-apparatus. To avoid applying fresh ink to the cylinder 20 when no sheet is fed, an arm 150, Fig. 3, which is slotted at 151 to receive a pin 79 on a pawl 77 normally rotating a duct roller and is connected to the arm 135, moves to the right when the roller 40 is tripped, whereby the pin 79 instead of riding freely in the slot 151 engages the end thereof, whereupon the pawl 77 is tripped and the duct-roller is no longer rotated.