GB1299263A - Printing machine blanket cylinder cleaning device - Google Patents

Abstract

1299263 Printing machines GESTETNER Ltd 19 April 1971 [4 Feb 1970] 5455/70 Head- B6C The blanket cylinder 1 of a printing machine is cleaned by a roller 2 rotatable about a fixed axis, the shape of the roller being such that as the roller makes one revolution its surface contacts the cylinder 1 for part of the time only. The roller 2 may be D-shaped, or have a gap 2A which also serves for mounting the securing means for a roller cover 44. During normal printing, the gap 2A is adjacent to the cylinder 1 so that there is no contact between the roller and the cylinder. Ratchet wheels 5, 6 on the roller shaft engages pawls 10, 11 carried by arms 8, 9. The ratchet wheel 6 has a circumferential space with no ratchet teeth. During a cleaning operation, arm 8 is actuated by cam means on the shaft of cylinder 1, and the roller 2 rotates intermittently preferably in the same direction as the cylinder, the pawl 11 acting as a retaining pawl. When the gap 2A is adjacent the cylinder 1, the pawl 10 has reached the untoothed part of the ratchet wheel 6 and cleaning is stopped. To start a cleaning operation, arm 9 is operated, e.g. by electromagnetic means after a predetermined number of revolutions of cylinder 1, so as to cause the pawl 11 to rotate the ratchet wheels 5, 6 and roller 2 until the pawl 10 can again engage the teeth of ratchet wheel 6 whereupon the roller 1 has imparted thereto a one-revolution wiping rotation. The parts 9, 11 may be dispensed with and means provided for lengthening the stroke of the pawl 10 to cause it to engage teeth when the roller 2 is to be rotated. The roller 2 is partly immersed in cleaning liquid in a trough 3 and may be engaged by a spring-pressed squeegee roller 4. When the liquid falls below a certain level it uncovers an air-hole so as to control the supply of liquid from a reservoir. A wiper blade 45 is provided on the roller 1, and the gap 43 for the blanket-securing means 42 is fitted with an absorbent pad 46 covered by a perforated plate 47. Liquid remaining on the blanket after cleaning is collected by the blade 45 and urged towards the pad 46 where it is first absorbed and then evaporated through the perforated plate 47.