Development of a System for Automatically Cleaning Blankets of a Web Offset Press

A system for automatically cleaning the blankets of a web offset perfecting press at printing speed is described. A complete system consists of a control box, a solvent metering box for each print unit, and a cloth handling unit for each blanket cylinder. The principle employed emulates a manual wash-up in that solvent is applied to a web of disposable cloth, which in turn is pressed against the blanket cylinder. Periodically the cloth is advanced and additional solvent is applied as necessary. Wash-ups, which are initiated by a button on the control panel, are carried out with the blanket cylinders on impression, the ink form rollers lifted, and the ink ductor roller silenced. At the completion of a wash-up, which typically takes 20 seconds, the press is automatically returned to printing condition. The number of signatures lost or wasted is about 250. Wash-ups, which are initiated by a button on the control panel, are carried out with the blanket cylinders on impression, the ink form rollers lifted, and the ink ductor roller silenced. At the completion of a wash-up, which typically takes 20 seconds, the press is automatically returned to printing condition. The number of signatures lost or wasted is about 250. In addition to describing the final system design, the paper provides information on blanket piling, blanket wash-up requirements, outlines some of the more significant development problems encountered, and describes some of the test work carried out as part of the development program. Wash-up performance using the automatic system is compared with average performance for manual wash-ups.