GB1076196A - Digital system for monitoring the diameter of a web-roll of printing presses of the like - Google Patents

Abstract

1,076,196. Feeding webs. MIEHLE-GOSSDEXTER Inc. Sept. 25, 1964 [Sept. 26, 1963], No. 39288/64. Heading B6B. [Also in Division G1] In web roll-changing apparatus of the type described in Specification 826,647, and illustrated in (Fig. 1), a control system monitors the diameter of the expiring web roll by measuring off in digital fashion a prescribed length of web and effecting a control operation when this corresponds to a prescribed portion of a rotation of the web roll, said control operation affecting web roll change-over and splicing operations. The operation of the control system illustrated in Fig. 2 is as follows. In response to the rotation of the expiring web roll (11A), a commutator 40 is rotated so that a triggering signal is produced at a brush 41C which opens a gate 46 to pass pulses induced in a magnetic pick-up by teeth 49 rotating at a speed determined by the speed of the web. The pulses are then fed to counter 52 which, when it has received a prescribed number, emits an output pulse which after shaping at 55 resets the counter 52 and closes gate 46. Additionally, a control pulse from the shaper 55 is transmitted through normally closed contact 56 to a pulse stretcher circuit 58, which produces an output pulse having a preset time period equal to the time required to perform the preliminary operation (described below) before the expiring web roll (11A) reaches the smallest desired diameter prior to splicing. When a reference pulse produced by the commutator 40 at a brush 41B and the stretched control pulse timingly overlap, a coincidence sensing circuit 45 is rendered operative to initiate operation of an output control circuit 60, i.e. initiates " first firing " thereof, and the output control circuit in turn initiates the preliminary operation of moving the paster carriage (30) into the operative position from its stowed position, plus positioning and pre-driving the new web roll, as described in Specification 826,647. Additionally, during the " first firing" the output control circuit 60 opens the normally closed contact 56 and closes the normally open contact 61 so that subsequent control pulses produced by the pulse shaper 55 are transmitted directly to the coincidence sensing circuit 45. Thereafter, when the reference pulse and a non-stretched control pulse timingly overlap, the coincidence sensing circuit 45 is again rendered operative to initiate the " second firing " of the output control circuit 60, which in turn initiates the splicing operation as described in Specification 826,647. Whilst the press is operating, pulses from the magnetic pick-up 48 are additionally fed to a safety circuit 62 which maintains a pilot light PL " on." If and when the press stops, the pilot light is extinguished. In a modification, the control pulse producing means comprising elements 46, 48, 49, 50 and 52 in Fig. 2, may be replaced by a zone magnetizable disc (250, Fig. 15) rotated proportionally to the web speed, which has a " print head " (251) a " read head " (252) and an " erase head " (253) associated therewith. During each revolution of the expiring web roll, a pulse is applied to the " print head " which causes a magnetic bar to be recorded. As the bar passes the " read head," a pulse will be induced therein which corresponds to the control pulse produced by the counter 52. The control pulse is likewise transmitted to the pulse shaper 55. The current pulse for the " print head " is produced at brush 41C, Fig. 2, and the time period between the production of said current pulse and the production of the control pulse corresponds to the passage of a prescribed length of web to the press. The time period between the reference pulse and the control pulse may be varied by varying the relative positions of the " print head " and the " read head ". The web roll diameter monitoring system described above may be applied to web winding machines.