Suction-air control for suction systems in turning drums of printing machines

摘要

The invention relates to a suction-air control for suction systems in turning drums of printing machines, in which the sheet can be printed selectively by face printing or perfecting, and the sheet is turned during perfecting according to the principle of trailing-edge turning by means of suction and gripper systems attached to rocker shafts, the suction-air control of the suction system being effected by means of a pneumatic valve which is cam-controlled and is acted upon by negative pressure. The object of the invention, to provide a suction-air control which requires no separate repositioning handling, has short control times and reduces the outlay, required in the turning drum, for the control of the suction air, is achieved in that a second suction-air control system (6; 8; 10); (15; 18; 19) is connected ahead of a first suction-air control system (7; 9; 11) disposed near to the suction system (5), and the first and second suction-air control systems (7; 9; 11); (6; 8; 10); (15; 18; 19) are provided to control the suction air, using function-related, rotary-angle-dependent movements in the turning drum (1) or of the turning drum (1). <IMAGE>