GB974024A - Improvements in or relating to rotary offset printing machines - Google Patents

Abstract

974,024. Rotary offset printing machines. W. RITZERFELD, and G. RITZERFELD. Dec. 5, 1962 [Dec. 22, 1961] No. 45900/62. Heading B6C. In an electrically actuated push-button operated sheet-fed lithographic rotary offset printing machine in which selective line printing may be accomplished and which comprises an offset cylinder 20, Fig. 1, swingable between a printing cylinder 1 and an impression cylinder 34, the cylinder 1 mounts a master sheet 3 the image of which is to be reproduced on every printed sheet and a master sheet 4 from which only selected lines are to be printed on any one sheet. Through electrically operated cams 181, 182, 183, Fig. 2, and 184, 185 (not shown) the used portions of the master sheet 4 are withdrawn into the interior of the cylinder 1 through the agency of a pawl 6 which is actuated by all or any of the cams 18 to thereby rotate a ratchet wheel 10 fixedly mounted on the shaft 12 of one of a pair of draw-in rollers 11, 13. Through the interengagement of toothed wheels driven from a single power source the three cylinders are rotated synchronously with an arm 90 which moves over a fixed contact bank 89 and in so doing initiates the various operations of the machine. The bank is electrically connected to a keyboard T1 ... T5, Fig. 5, and TE and electromagnets 103 ... 107 and 28, 31 and 125. Each key T1 ... T5 is in the electrical circuit responsible for the selection for printing of a particular line or group of lines of the master sheet 4 whilst the key TE comprises an over-riding control switch. The magnets 103 . . . 107 actuate appropriate cams 18- one for each key-whilst the magnets 28 and 31 energize the lever linkage eccentric mechanism 23 . . . 27 for swinging the offset cylinder 20 into and out of engagement with respective cylinders 1, 34. The magnet 125 actuates a clutch arrangement 81, 87, Fig. 4, whereby the drive to the offset cylinder through the normal operational toothed wheels is disengaged whilst another toothed wheel train, also deriving from the single power source, engages and drives the offset cylinder forwards relative to the cylinder 1 to such an extent that the previous impression made by the master sheets on the cylinder 20 is placed out of registration with the cylinder 1. When the rubber blanket 21 of the cylinder 20 is completely used it may be cleaned by a washing mechanism 41. The means for advancing the master sheet 4 and for altering the phase of the cylinder 20 may be disabled to allow a plurality of copies to be made from the same master part. In a further machine the clutch 81, 87 is replaced by an electromagnetically operated pawl-and-ratchet mechanism. Instead of two master sheets one may be used, the parts not desired for printing being guided into the interior of the printing cylinder. In a further form, the offset cylinder is held back relative to the impression cylinder after each cycle.