Method and apparatus for controlling curvature in printed sheets being withdrawn from an impression cylinder

Claim 1

IN COMBINATION WITH THE IMPRESSION CYLINDER OF A PRINTING PRESS AND MEANS FOR WITHDRAWING SHEETS FROM SAID CYLINDER INCLUDING SPROCKET MEANS LOCATED BELOW SAID CYLINDER AND CARRYING CHAIN MEANS PROVIDING AN UPPER HORIZONTAL RUN LEADING TO THE IMPRESSION CYLINDER AND A LOWER HORIZONTAL RUN LEADING AWAY FROM THE IMPRESSION CYLINDER, A SHAFT CARRYING THE SPROCKETS, GRIPPING MEANS CARRIED BY SAID CHAIN MEANS FOR ENGAGING LEADING EDGES OF THE SHEETS TO CARRY THEM AROUND THE SPROCKET MEANS, AND CURVED GUIDES BACKING SAID SHEETS AS THEY AR CARRIED AROUND SAID SPROCKET MEANS, APPARATUS FOR CONTROLLING CURVATURE OF SAID SHEETS AS THEY ARE PULLED FROM THE IMPRESSION CYLINDER, SAID APPARATUS INCLUDING A MAIN DUCT OF LARGE CAPACITY EXTENDING TRANSVERSELY BETWEEN SAID UPPER AND LOWER RUNS IN SPACED PARALLEL RELATION WITH SAID SHAFT, MEANS RIGIDLY SUPPORTING THE MAIN DUCT, LATERAL DUCTS SPACED ALONG AND PROJECTING FROM THE MAIN DUCT AND TERMINATING OVER SAID SHAFT, NOZZLES ON THE TERMINAL ENDS OF THE LATERAL DUCTS HAVING SIDES FORMING CONTINUATIONS OF SIDE WALLS OF THE LATERAL DUCTS AND TOP AND BOTTOM WALLS, WITH THE BOTTOM WALL CURVING DOWNWARDLY OVER THE SHAFT AND THE UPPER WALL CURVING IN THE GENERAL DIRECTION OF THE IMPRESSION CYLINDER, TO COOPERATE WITH SAID SIDE WALLS IN PROVIDING A WIDE OPEN OUTLET THEREBETWEEN THROUGH WHICH AIR IS DISCHARGED IN LARGE VOLUME OVER A SHEET BEING WITHDRAWN FROM THE IMPRESSION CYLINDER AND FOR HOLDING SAID SHEET SUBSTANTIALLY FOLLOWING THE CURVED GUIDES WHICH BACK SAID SHEETS.