Device for fastening flexible printing plates

Claim 1

In a plate lock-up mechanism for securing and adjusting a flexible printing plate upon a plate cylinder which has a longitudinal groove formed therein defined by side walls, end walls and generally flat bottom wall, the combination comprising a supporting plate member of L cross section made up of horizontal and vertical portions at right angles to one another respectively seated against the bottom and side wall of the groove and extending substantially the length thereof, the supporting plate member having bracket means along one edge in spaced opposition to the vertical portion, a plurality of mounting bars spaced end to end in the groove above the supporting plate member, means including guide bars interposed between the mounting bars and the supporting plate member for holding the mounting bars individually captive thereon while permitting limited shifTing movement both circumferentially and axially, each of the mounting bars having a coextensive rail for tightly holding the edge of a printing plate, circumferentially oriented springs interposingly compressed between the bracket means and the individual mounting bars for biasing the mounting bars circumferentially in the direction of the vertical portion of the supporting plate member, first screw means in each bar extending circumferentially bearing against the vertical portion of the supporting plate member for adjusting each bar and its printing plate circumferentially with respect to the cylinder, second screw means in each bar for adjusting each bar and plate axially with respect to the cylinder, and a set of supporting screws for clamping the supporting plate member securely against the bottom of the groove, the supporting plate screws being positioned such that the axes of the screws, when extended past the head ends of the screws, are substantially free of any obstruction by any other part of the plate lock-up mechanism so that the screws are readily accessible for easy and unobstructed application of an unscrewing tool notwithstanding the presence of the plate mounting bars whereby, upon removal of the screws, the supporting plate member and the mounting bars and associated biasing springs which are captive thereon may be removed as a unit from the cylinder while preserving the adjusted positions of the bars relative to the supporting plate member and while preserving the compressed condition of the biasing springs for substitution in the groove of a single plate mounting bar extending the length thereof.