No-lock printing plate assembly using flexible plates

摘要

A "no-lock" printing plate assembly including a plate cylinder having a smooth plate-supporting surface interrupted by an axial groove defining leading and trailing edges, at least the leading edge having a flat undercut end face with a register pin anchored therein. The plate is formed of a thin sheet of resilient material having a smooth undersurface and which is bent over adjacent its ends to define leading and trailing edge portions having respective longitudinal notches, the bend adjacent the leading edge making an acute angle and the bend adjacent the trailing edge making a wide obtuse angle. The width of the gap is substantially greater than twice the plate thickness and the edge portions of the plate are spaced and dimensioned so that when the plate is installed the bends are peripherally spaced from one another to provide clearance between them. The trailing edge portion of the plate is outwardly sprung causing the trailing edge of the plate to be in pressing engagement with the leading edge portion. "Ironing" of the plate by a cooperating cylinder results in the taking up of at least a portion of the clearance between the bends and cyclically renews a vacuum seal under the plate tending to hold the plate in position notwithstanding the effect of centrifugal force.