Gapless lock-up for offset printing cylinders

Claim 1

In a cylinder of a high speed rotary offset web printing machine, gapless lock-up means for an offset plate or a metal backed offset blanket with metal end tabs, said lock-up means comprising, in combination: a slot in the cylinder surface extending substantially the entire length of the cylinder, said slot being provided with an outwardly facing arcuate surface that is concentric with the cylinder surface; a fixed jaw and a movable jaw mounted in and occupying the full length of said slot and defining a recess, said jaws having extended arcuate outer surfaces flush with the surface of the cylinder and having facing undercut surfaces the outer margins of which intersect said arcuate outer surfaces along small radii of curvature so that an offset plate or blanket having metal end tabs wraps smoothly around the cylinder with said end tabs lying in uninterrupted facing contact with said outer margins and said undercut surfaces of said jaws, said movable jaw having a multiplicity of inclined recesses spaced generally evenly along a surface that is remote from the fixed jaw, and said movable jaw being seated on said outwardly facing arcuate surface; intermeshing flanges at the inner margins of said undercut surfaces, said flanges having top faces that cooperate to define the bottom of the recess; and rigid means for applying effectively uniform lateral force to the movable jaw throughout its length so as to impart translatory motion to said movable jaw across said outwardly facing arcuate surface between an open position and a closed position in which the end tabs at opposite ends of an offset plate or blanket are firmly and rigidly clamped against one another between the undercut jaws immediately adjacent the outer margins of said jaws, said rigid means comprising a rotatable screw with an arcuate groove that extends substantially the entire length of said movable jaw immediately adjacent said inclined recesses, and a ball in each recess engaged with the groove.