GB918378A - Improvements relating to printing machines - Google Patents

Abstract

918,378. Printing-machines. ADDRESSOGRAPH-MULTIGRAPH CORPORATION. Sept. 7, 1960 [Sept. 14, 1959], No. 30835/60. Class 100 (2). Damping-apparatus.-Apparatus for applying an ink-repellent liquid to the printing cylinder 13 of a lithographic machine comprises a fountain 44 for the liquid in which is a constantly-rotating fountain roller 51, a ductor roller 56 engaging the roller 51 and adapted to be swung intermittently about the axis of the roller 51 into engagement with a distributer roller 52 by a cam 115 rotatable with the printing cylinder 13, and operating means arranged between the cam and the ductor roller which includes a cam follower 141, Fig. 2, mounted for adjustment on the carriage 59 of the roller 51, so that the portion of the rotational cycle of the cam 115 which is effective to swing the ductor roll can be varied. The distributer roller 52 applies the ink-repellent liquid to the forme roller 18, which applies both the ink and the repellent to the master sheet on the printing cylinder 13. The whole of the ink-repellent unit is removably mounted in brackets 42 on side frame members 12 of the machine. The fountain 44 is supplied with liquid from a bottle 46 and an automatic valve of known kind, and can be drained by a hose 47. The distributer roller 52 is supported in frames 53 pivoted on stub shafts 54, and the roller can be separated from the forme roller 18 for working-up purposes by operating a hand-lever 83 which rocks a cam 77 into engagement with one frame 53. The ductor roller 56 is mounted in the carriage 59 pivoted about the axis of the fountain roller 51, and is spring-urged against the roller 51 under the control of adjustable knobs 61. When the ductor carriage 59 is swung upwardly to move the ink-repellent unit away from the forme roller 18, the ductor roller 56 is automatically spaced from the fountain roller 51, and the roller 56 from the roller 52; this movement is facilitated by slotted link members 68 which interconnect the carriage 59 and the frames 53, and by the action of fixed cams 64, 66. A roller 92, which acts to remove surplus liquid from the surface of the fountain roller 51, is adjustably engageable with the roller 51 by a spring- biased lever arrangement 93, 97, 99. Each end of the carriage 59 has a cam follower 141 engageable by a constantly driven cam 115 to swing the ductor roller 56 out of engagement with the distributer roller 52, and each follower 141 is mounted on an adjustable eccentric pin, and can also be bodily adjusted relative to the cam 115 by a manually operable knob 116. The knob 116 acts through gearing 169, 164 and an eccentric which adjusts a rectangular plate slidable in a rectangular slot in a secondary member. The secondary member rocks a primary member carrying the ductor roller. Thus, the amount of liquid transmitted to the distributer roller 52 can be adjusted by varying the period of contact between the rollers 52, 56; this adjustment is facilitated by a pointer 173. The metering roller 92 has a rubber outer covering, and the fountain roller 51 and distributer rollers 52 have grained or granulated surfaces which are porous to store the inkrepellent liquid. The surfaces of the rollers 51, 52 may be of steel which has been blasted with aluminium oxide grit to produce pores having a depth of 125 to 140 micro-inches, and then plated with chromium to a depth of 0.0015 inch to 0.002 inch, so that the pores are finally 110 to 120 micro-inches deep. In modifications, the surfaces of the rollers 51, 52 may be formed of granulated plastic, ceramic, glass, or a paperbase rigid plastic. The printing cylinder 13 is adjusted relatively to the blanket cylinder 14 by a hand-lever 16 and an adjustable link 17. Each of the forme rollers 18 is in eccentric mounts adjustable by hand-levers 19.