Patent GB-984528-A (GB)
Title: Rotary offset printing machines
Inventor: LEIN WERNER
IPC: B41F33/06
Filed: 1961-03-14
Abstract: 984,528. Printing processes; feeding sheets. DRUCKMASCHINENWERK PLANETA VEB. March 14, 1961, No. 9286/61. Headings B6B and B6C. A sheet-fed rotary offset printing press having sheet supplying and automatic sheet feed mechanisms and means for cutting off pressure between printing cylinders is controlled by an electrical system which provides feelers and detectors such that if a " minor " fault, e.g. a double sheet feed, should occur the press speed is automatically reduced whilst if a " major " fault such as a crumpled sheet feed arises the press is automatically stopped. Using the electrical circuit shown in the drawing the operation of the machine is as follows. When the machine is to be actuated a switch 6 and a starting contact 7 must be closed. On the operation of a switch 4 a relay 1 operates thus starting the drive motor of the machine at slow speed. The relay 1 holds itself through contact 1.1 and through contact 1.2 prepares for the switching on of the " regulation operation " (i.e. building up of speed of the motor), which is achieved by the operation of a control switch 5 which operates relay 2 which relay holds itself through its contact 2.1. When the automatic feed mechanism has been switched on, a switch 8 and its contacts 8.1 and 8.2 are closed, for example, by cam means as shown diagrammatically at the top of switch 8, and after the printing cylinders have moved to their printing position a switch 9 and its contacts 9.1 and 9.2 are closed by cam means as shown diagrammatically at the top of switch 9. The removal of the printing cylinders to their inoperative position, the stopping of the automatic sheet feed mechanism and thereby the stopping of the sheet supplying mechanism are initiated by two solenoids 14 and 15 through a relay 3 with its contacts 3.3 and 3.4, while through the contact 1.3 of the relay 1 the circuit is closed as far as the connection point 11, provided the drive motor has been started at its slowest speed or " regulation operation " has begun, i.e. provided relay 1 has been operated. In the event of a " minor " fault, e.g., the feeding of a sheet to the sheet supplying mechanism or the automatic sheet feed mechanism askew or the feeding of a double sheet, the relay 3 is operated by the action of the contacts of a spoil sheet control device 10 or of a double sheet control device 12; the automatic sheet feed mechanism is stopped, which simultaneously stops the sheet supplying mechanism and the printing cylinders are brought out of their printing position by means of the solenoids 14 and 15, and through the contact breaker 3.2 the holding line of relay 2 is interrupted, whereby the relay 1 takes charge and thus the drive motor is switched over to slow speed. In the event of a " major " fault, e.g. the introduction of crumpled sheets or foreign bodies, e.g. tools or other articles between the printing cylinders, the switch 6 is opened whereupon the relay 1 returns to its non-operative position, thus immediately stopping the machine and closing the contact 1.4 whereby the relay 3 is operated, and thus the same operations are brought about as in the case of a minor fault, with the exception of changing over to low speed. The stop switch 6 may be controlled manually or automatically by emergency switches or other known control or operating devices, connected in series at any desired points on the press.