Gripper control device for sheet handling machines

1,148,017. Gripper mechanism. DRUCKMASCHINENWERK PLANETA VEB. 11 April, 1967, No. 16445/67. Heading B6C. A gripper control device, whereby the grippers carried on a rocker shaft are opened and closed by a cam disc through a lever carrying a cam follower, a coupling rod, and a further lever connected to the rocker shaft, has the pivot connecting the coupling rod and the cam follower lever lying in alignment with the centre of the rocker shaft when the grippers are closed. The device is especially applicable to multicolour rotary sheet printing machines, the grippers being located on rocker shafts located eccentrically of each transfer cylinder axis. Figs. 1 and 3 illustrate a transfer cylinder 1 and a rocker shaft 2 mounted in the cylinder; fixed to rocker shaft 2 are a number of rocker arms 4 carrying the gripper shaft 3 and a number of holders 5 carrying a gripper facing-piece rail 6; the gripper shaft 3 carries the grippers 7. When the rocker shaft 2 is rotated by a drive (not shown), the gripper shaft 3 with associated grippers 7 and the holders 5 with rail 6 swing inwards towards the middle of the cylinder to effect sheet transfer. A cam roller 15 rides on cam path 18 of a disc 17 attached to the machine wall; a lever 13 mounted on central pivot 14 is articulated to the cam roller 15 and at the other end to a coupling rod 11 by means of bolt 12. The coupling rod 11 is, in turn, articulated at bolt 10 to a further lever 9 fixed to gripper shaft 3. Thus movement of lever 13 is transmitted through coupling rod 11 and lever 9 to the grippers shaft 3, and the cam disc 17 therefore controls movement of grippers 7. When the centre of bolt 12 and of the rocker shaft lie in one alignment with the grippers 7 closed (Fig. 4, not shown), then the swinging movement of the whole gripper system 8 about the rocker shaft causes no relative movement between the grippers 7 and rail 6, i.e. they remain closed. Only when the centres are moved out of alignment (Fig. 5, not shown) do the grippers open; thus the cam disc 17 and path 18 is arranged to open the grippers as required. Inaccuracies in the alignment will cause the grippers to open at the wrong moment; in order to prevent this, the alignment is checked with an adjusting bolt (21) which is introduced simultaneously into the cam follower lever bore (22) and the rocker shaft bore (23) (Figs. 6, 7, not shown). The grippers 7 can be similarly checked by introducing the bolt (21) into the coupling rod bore (24) and the ro