Verso printing unit in the delivery of a sheet-fed rotary printing press

Abstract

An apparatus for printing the back, or 'verso', side of a sheet being fed from a sheet-fed printing press into a delivery unit, the sheets being conveyed by an endless loop conveyor made up of a pair of laterally spaced conveyor chains. Cross members extend between the chains at regular intervals and carry grippers for gripping the leading edge of a sheet. The chains are guided so that they form a delivery run and a return run spaced apart and generally parallel to one another. An impression cylinder is journalled between the runs having an axial length which is shorter than the lateral spacing between the chains. A blanket cylinder is journalled outside of the delivery run in rolling engagement with the impression cylinder. A plate cylinder having inking and dampening systems is in rolling engagement with the blanket cylinder. The impression and blanket cylinders have mating longitudinal grooves of a size sufficient to provide free passage for the cross members and grippers. The spacing between the successive cross members is equal to the circumference of the cylinders. The cylinders are driven in synchronism with the conveyor chain so that a sheet passing on the grippers is engaged between the impression and blanket cylinders for application of a printed impression to the sheet. The speed of the conveyor is less than press speed in a predetermined ratio. The cylinders are all of the same diameter, which diameter is less than the diameter of the cylinders in the associated press unit in the same ratio.