Abstract:
A method for registering in an offset printing press comprises: mounting a printing plate on a shiftable table of a plate bending machine; detecting datum fine lines on said plate, by means of optical sensors; shifting the shiftable table so that said datum fine lines are placed at specific positions; inscribing, by means of a register mark inscribing device, register marks for carrying out automatic registering while, at the same time, bending the lateral edges of the printing plate; thereafter mounting the printing plate on a corresponding plate cylinder of a printing press; and carrying out automatic registering. The above plate bending machine comprises plate bending mechanisms, a shiftable table for holding the printing plate, optical detection sensors disposed above the shiftable table and operating to detect datum lines on the plate and thereby to generate signals for the movement of the table and register mark inscribing devices for automatic registering on a plate cylinder of the printing press.