Screwing tool for printing presses

US4158799A · kind A · utility

Assignee

• Roland Offsetmaschinenfabrik Faber & Schleicher AG

Inventors

• Bert Cappel · Mühlheim, DE
• Alfred Dorn · Mühlheim, DE

Key dates

• Filing date: Aug 2, 1977
• Grant date: Jun 19, 1979
• Expiry date: Aug 2, 1997

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B25B23/147
• WIPO field: Machine tools
• WIPO sector: Mechanical engineering

Abstract

A control system for a reversible screwing tool for tightening and loosening screws in a printing press or the like which includes a pair of angularly spaced pick-up devices coupled to the shaft of the tool for generating respective series of impulses. Monostable pulse generators are coupled to the respective pick-up devices, the generator coupled to the pick-up device in leading position, for counterclockwise rotation, being set to produce an output pulse which is substantially wider than that produced by the generator which is connected to the pick-up device in trailing position so that during counterclockwise rotation the output pulses from the generators timingly overlap one another. The generators feed into the input terminals of an AND gate which is, in turn, connected to a counter which counts the pulses resulting from counterclockwise rotation of the shaft. A relay interposed between the source and the tool automatically turns off the tool when a predetermined count is achieved thereby insuring that the screw is not excessively unscrewed from its tight condition. The relay is resettable in readiness for engagement of the succeeding screw. In the preferred embodiment of the …