Wet nip dampener

Claim 1

In a printing press having a structural frame, in combination: a plate cylinder mounted in the frame for rotation about the cylinder longitudinal axis, and having a cylindrical surface and a longitudinal recess in said cylinder cylindrical surface for receiving the attachment ends of a lithographic printing plate; a lithographic printing plate supported by said cylinder cylindrical surface, having a plate cylindrical surface conprised of ink-receptive, printing surface areas in combination with dampening fluid-receptive, non-printing surface areas co-planar to said printing surface areas and rotated at a selected printing surface speed, and having attachment ends spaced apart by a gap width and secured to said plate cylinder at said plate cylinder longitudinal recess; a plurality of elongated ink roller members having cylindrical surfaces engaging said lithographic printing plate cylindrical surface at circumferentially spaced-apart positions relative to said plate cylinder, and applying ink to said printing plate printing surface areas from ink films extending substantially throughout the lengths of said ink roller member cylindrical surfaces; a resiliently-surfaced dampening fluid roller member rotated in non-contacting relation to said ink roller members, having a cylindrical surface of different diameter than said plate cylindrical surface, and applying a film of dampening fluid to said lithographic printing plate non-printing surface areas in each revolution of said plate cylinder during printing and in advance of the application of films of ink to said printing plate printing surface areas by said ink roller members; first drive means rotating said dampening fluid roller member in non-slipping, contacting relation to said lithographic printing plate cylindrical surface: a non-resiliently surfaced fountain roller member positioned generally horizontally with respect to said dampening fluid roller member, and having a cylindrical surface engaging said dampening fluid roller member cylindrical surface in slipping relation; a body of dampening fluid defined in lateral extent by said dampening fluid roller member cylindrical surface and by said fountain roller member cylindrical surface adjacent their zone of initial engagement; second drive means rotating said fountain roller member relative to said dampening fluid roller member in a manner whereby said fountain roller member cylindrical surface has a speed in an opposite direction relative to said engaged dampening fluid roller member cylindrical surface substantially greater than said lithographic printing plate selected printing surface speed; and blade means engaging said fountain roller member cylindrical surface in scraping relation throughout its longitudinal extent exteriorly of said body of dampening fluid, said dampening fluid roller member cylindrical surface, at zones registered with said printing plate attachemnt ends gap width, being rotated through said body of dampening fluid and afterwards eNgaged with circumferential portions of said fountain foller member cylindrical surface scraped by said blade means to meter dampening fluid applied to said lithographic printing plate cylincrical non-printing surface areas to a sub-micron film thickness.