Patent GB-219725-A (GB)
Title: Improvements in or relating to printing presses
IPC: B41F33/08
Filed: 1923-04-03
Abstract: 219,725. Anglo-American Inventions Syndicate, Ltd., (Harris Automatic Press Co.). April 3, 1923. Rotary machines ; offset machines; tripping-arrangements. - A multicolour rotary direct or offset printing- machine in which a sheet is printed successively in different colours by successive printing-couples is provided with a manual or automatic tripping mechanism so arranged that the tripping of the first couple sets mechanism to cause the tripping of the second couple, the subsequent couples being similarly tripped so that a sheet taken by the first couple will be printed in all the colours before the later couples are tripped. The invention is described in connection with a two-colour offset machine in which a sheet transfer cylinder 31, Fig. 1, is arranged between impression cylinders 22, 27 coacting respectively with offset cylinders 21, 26, and plate cylinders 19, 25. The cylinder 27 delivers the printed sheet to a delivery cylinder 33 from which the sheets are taken by known delivery means. The various cylinders are so arranged that access can be easily had to the same, the planes containing the axes of the offset and printing cylinders being perpendicular to the planes containing the axes of the offset and impression cylinders. The machine is fitted with adjustment mechanism for the impression cylinders, the transfer cylinder, and the delivery cylinder, combined with a scale device for indicating the amount of adjustment necessary for dealing with sheets of different thicknesses. The impression tripping mechanism is arranged to cause the inking- rollers to be tripped at an interval which is timed to cause the rollers to be lifted when they are passing the gaps in the forme or plate cylinders. The offset cylinders 21, 26, are mounted in eccentric bearings which are capable of being rotated to throw-off the impression by means of compound toggle mechanism 90 - - 94, 96 - - 98, operated from adjustably mounted cams 60 on the shafts of the impression cylinders 22, 27. The cams 60 reciprocate an adjustably mounted rod 76 carried by a bracket 69 pivoted to the arm 62 of a bell-crank lever 62, 72, connected by a link 70 to the bracket 69. The lever arm 72 is connected to a manual lever or to stock-controlled tripping mechanism such as is described in Specification 218,001, and the end 77 of rod 76 is caused to be moved from its normal position shown in Fig. 1, in which the rod 76 is caused to maintain toggle levers 93, 97 in a straight position, to a position in which the rod 76 acts at the predetermined time via a lever 80, link 86, levers 85, 90, 91 to break the toggle 93, 97 and throw-off the impression. The breaking of the toggles 93, 97 throws in mechanism for tripping the inking rollers 47, 48. A link 105 connected to the toggles and controlled by a fixed roller 108 engaging a cam surface on the side of the link moves a lever arm 102 so as to bring a roller 103 on the arm in the path of a cam 100. The cam at the predetermined time oscillates the lever arm 102, and its arm 109 is thus caused to straighten a toggle lever 110, Figs. 1 and 17, and a pawl 116 on a freely mounted arm 112 is caused to move a freely mounted sleeve 113 formed with ratchet teeth 115 engaged normally by pawl 116. The sleeve 113 is thus moved anticlockwise by lever 110, and an arm 120 on the sleeve depresses a rod 59 and thus actuates a lever 58 to rotate levers 50, 51 so as to trip the ink rollers. The sleeve 113 is fitted with a hand-lever 121 with pawls 123, 124 for operating the sleeve to trip or restore the ink-rollers by a hand-manipulation of the lever. The second offset roller is adapted to be tripped at a predetermined interval after the tripping of the first offset roller, and the tripping means for the second roller is of similar construction to that described for the first but is put into operation by the actuation of the first mechanism through the medium of a relay mechanism shown in Figs. 7 and 8. This comprises a rock lever 171 which is normally oscillated so that a latch 180 is out of the way of a pin 182 on a carch 183 which controls the motion of a lever arm 72 for bringing the rod end 77 over the lever end 81 so as to cause cam 60 to trip the cylinder as in the first case. A rod 190 connected to the first trip mechanism operates an arm 189 to which is fitted a cam plate 188 for controlling the latch 180 and bringing it into the path of the pin 182, so that the catch 183 then permits the cam 60 to break the toggles 93, 97 and trip the offset cylinder 26. The ink trip is operated from this offset cylinder tripping means.