GB869983A - Sheet transfer mechanism for rotary printing presses - Google Patents

Abstract

869,983. Printing machines. MIEHLEGOSS-DEXTER Inc. June 3, 1959 [Aug. 21, 1958], No. 18952/59. Class 100(2) Mechanism for transferring sheets from an impression cylinder to another cylinder in a rotary printing press comprises a series of grippers mounted for rotation about a fixed axis in a circular path having a point of tangency with each of the cylinders, a concave shell member having a radius of curvature slightly greater than the radius of the gripper path, mounted adjacent to the gripper path and extending substantially between the points of tangency for guiding the sheet along the gripper path, and a transverse vane member mounted for movement with the rotating grippers and coacting with the shell member to create a differential of air pressure upon the two faces of the sheet whereby the body of the sheet is maintained in contact with the shell member while the sheet is advanced by the series of grippers. As shown a multi-colour press comprises two printing couples A, B. Printed sheets are fed from the impression cylinder 10 of printing couple A to the impression cylinder 13 of the printing couple B for a second impression by three rotary transfer members 20, 21, 22. The member 21 is a full-sized transfer drum round which the sheets are carried printed face outwards. The members 20, 22 are substantially identical and each comprises a drum 27, Fig. 4, from which radially extend brackets 26, 31. The brackets 26 support a gripper shaft 25 on which is mounted a series of gripper fingers 24 each co-operating with a pad 28 mounted on a bar 29 supported by the brackets 31. The drum 27 is journalled in the side plates of the machine by members 33 which are eccentrically disposed on the drum so as to counterbalance the gripper assembly. The transfer members 20, 21, 22 are rotated in timed relation with each other and with the impression cylinders. The grippers 24 are operated by a cam follower on the shaft 25 which engages a cam track secured to one of the side plates of the machine. A curved shell member 48, supported by bars 49, 50, is mounted adjacent to the gripper path and extends substantially from the point where the grippers 24 receive a sheet from grippers on the impression cylinder or the cylinder 21 to the point where the grippers 24 release the sheet. As the transfer members 20, 22 rotate the bar 29 on each functions in much the same way as the vane of a pump to remove a substantial amount of the air from adjacent to the inner surface of shell whereby the sheet held by the grippers 24 is maintained in contact with the shell until it is released by the grippers. To prevent the trailing edge of the sheet from falling away from the shell as the sheet is being transferred to the impression cylinder 13 blasts of air are directed against the inner face of the sheet from a perforated tube 57.