Patent GB-764677-A (GB)
Title: Improvements in or relating to rotary printing machines
IPC: B41L29/00
Filed: 1955-02-22
Abstract: 764,677. Rotary printing machines. ADDRESSOGRAPH-MULTIGRAPH CORPO. RATION. Feb. 22, 1955, No. 5302/55. Class 100(2) A gripper mechanism for securing a master sheet to the printing cylinder of a duplicating or like machine comprises a series of grippers each having a clamping washer, 30, Figs. 1, 4, mounted on a pin 26 slidable in a bracket 25 and urged by springs 31 to the clamping position, operating mechanism being provided for lifting alternate grippers upon rotation of the cylinder in the non-printing direction to a first position and for lifting all the grippers upon similar rotation to a second position. By this means a first master sheet may be secured to the cylinder and a second overlying master sheet or a masking sheet may be secured to the cylinder without disturbing the first master sheet. The gripper mechanism is mounted in an axial gap 20 in the surface of the printing cylinder 11 and the bracket 25 .is secured along one wall 23 of the gap as shown in Fig. 4. The top surface of the bracket acts as an anvil 28, Fig. 8, against which the master sheet is gripped. The ends of the gripper pins 26 project into the cylinder and co-operate with a lifting bar 40 running the length of gap 20 and carried on arms 41 swingable about a spindle 42. An arm 36 secured to spindle 42 is frictionally secured to arm 41 at 39 and the relative positions of these arms can be adjusted by a screw 27 on a lip 37 of arm 41 bearing on the side of arm 36. Outside the end wall 43 of the cylinder the shaft 42 carries an arm 44, Fig. 6, on which is mounted a spring-loaded pawl 45, normally co-operating with a stop 46. A stationary cam member 65 is mounted on the frame 10 for cooperation with the pawl. In normal anticlockwise rotation for printing the pawl strikes the cam 65 and is displaced against its spring without moving the arm 44. When the cylinder is moved in a reverse direction (see arrow in Fig. 6) the pawl engages recesses 65b, 65a in the cam and displaces the arm 44, shaft 42 and bar 40 in an anticlockwise direction. A handle 19, Fig. 1, engaging the cylinder shaft may be used to rotate the cylinder backwards. The gripper pins 26a, Fig. 12, of alternate grippers are shorter than the others 26b so that in its first movement the bar 40 lifts the grippers having the longer pins 26b. This corresponds to the cylinder position shown in Fig. 6 where pawl 45 engages the recess 65b. Further clockwise rotation of the cylinder causes the pawl to engage in recess 65a and displaces the bar 40 a further amount so that all the grippers are raised as shown in Fig. 8. In this position a main master sheet A is inserted and clamped by anticlockwise movement of the cylinder. On moving the cylinder clockwise again to engage the pawl 45 with recess 65b grippers having the longer pins 26a are lifted so that an overlying sheet B can be inserted as shown in Fig. 10. These grippers are again allowed to move to gripping position by anticlockwise rotation of the cylinder. The circular washers 30 of the grippers act as clamping heads and cooperate with sharpened spurs 33 so as to pierce the master sheets A, B and hold them securely in place. The washers on the end grippers are replaced by registering guides 70 for the master sheets. Pins 71 pass through openings in the bracket 25 and prevent rotation of the guides. The trailing end of the master sheet may be clamped against a slotted shelf 51 by a gripper bar 53 which is sliding and pivoted on pin 56 and pulled into clamping position by a spring 57. Spikes 59 on bar 53 pierce and grip the master sheet.