GB1163854A - Lithographic Dampener with Skewed Metering Roller - Google Patents

Abstract

1,163,854. Lithographic press. H. P. DAHLGREN. 2 Aug., 1967, No. 35565/67. Heading B6C. Apparatus for applying ink and dampening fluid from the same applicator roller to a lithographic plate on a rotary press comprises an axially reciprocating inking roller contacting the resilient applicator roller on one side, and a smooth, hard transfer roller for the dampening fluid on the other side, the transfer roller being, in turn, in contact with a resilient metering roller, means being provided for altering the relative speeds and pressure relationships of the rollers, wherein the metering roller may twist spirally about the transfer roller by moving at least one end of the metering roller about the longitudinal axis of the transfer roller in order to regulate the film of dampening fluid intermediate the ends of the rollers. Figs. 1 and 2 illustrate a general arrangement in which a plate A is in contact with a forme roller 11 comprising a metal core 12 and a smooth resilient non- absorbent covering 13; the forme roller is inked by an axially reciprocating roller B, and is treated with dampening fluid from a hard hydrophilic fountain roller 14 dipping into a fountain 5, a metering roller 15, having a resilient covering 17, regulating the thickness of the fluid film. The forme roller 11 can be swung in and out of contact with the plate A and the fountain roller 14 by means of a forme roller hanger 18 which pivots under the action of pneumatic cylinders 20 (also Fig. 9, not shown). The metering roller 15 and fountain roller 14 are carried in bearing housings 51 (also Figs. 9, 20 and 21, not shown) which may be rotated about the axis of the fountain roller and may be locked in position by bolt 60; the metering roller 15 is carried in self-aligning bearings (53), and the block (52) which carries these bearings is slidably mounted for movement towards and away from the fountain roller, adjustment screw 52a operating against springs (54a). Drive means include a variable-speed motor 71 and gears operable to rotate the metering roller at a lower speed than the fountain roller, an overriding clutch (Fig. 14, not shown) being provided for the fountain roller if the dampening fluid is absent, and brake means (Fig. 11, not shown) preventing overdriving of the rollers from the press.