GB223316A - Improvements in or relating to apparatus for gumming lithographic printing surfaces - Google Patents

Abstract

223,316. Linotype & Machinery, Ltd., and Goulding, B. J. J. July 20, 1923. Rotary offset machines; printing-surfaces; gumming-apparatus. - Lithographic printing- machines are provided with apparatus for applying a protective coating of gum to the printing- surface prior to stopping the press, the apparatus comprising a power-operated roller having an operative surface of absorbent resilient material receiving gum from a trough, and means for bringing the roller into and out of contact with the printing-surface. In a machine, such as a rotary offset press, having a number of plate cylinders each equipped with the gumming- apparatus, means may be provided for operating the gumming-apparatus collectively or individually. A special cleaning-apparatus may be provided for removing the gum on restarting the machine. A gum-applying roller 6 continuously contacts with a roller 3 rotating in a gum-trough 2 and driven by bevel gearing 40, 41 from a shaft 42. The roller 6 is carried in a pair of arms 5 which mav be rocked about the axis of the shaft of the roller 3 by a hand lever 7 to move the roller 6 into and out of contact with the plate on the printing-cylinder 1. To allow the rollers 6 of a number of plate cylinders to be operated simultaneously, the levers 7 are connected by spring plungers 8 to vertical rods 9, connected by linkage to a hand-lever arranged adjacent to the folding mechanism of the machine. Individual operation of any of the gumming-rollers may be effected by withdrawing the corresponding plunger 8. A thin coating of gum may be removed by the ordinary damping-apparatus, but for thick coatings a special cleaning-apparatus is provided comprising a pair of rollers 19, 20 in continuous contact with a roller 17 rotating in a trough 16 of cleaning fluid and driven by gearing 38, 39 from the shaft 42. The rollers 19, 20 are mounted in arms 21, 22 pivoted about the axis of the roller 17 and connected by links 23, 24 to a double-armed lever 25 on a shaft 26 provided with a hand-lever 28. Depression of the hand-lever 28 moves the rollers 19, 20 into contact with the plate cylinder. Collective and individual operation of the cleaning-apparatus may be effected by connections similar to those employed for the gumming-apparatus. To allow the rollers 3, 17 to be stopped when the machine is running normally, the shaft 42 may be disconnected from the driving-shaft 44 by a clutch 43. The rollers 6, 19, 20 may be reciprocated axially and the control of the gumming and cleaning apparatus may be associated with that of other organs of the press. Foot-operated devices may be employed instead of hand-levers for operating the rollers. The Provisional Specification describes a pin-and-slot connection between the levers 7 and rods 9 and states that the means for simultaneously operating the gumming-rollers may be interconnected with mechanism for tripping the cylinders or the inking and damping rollers, or for stopping the web-feeding apparatus. It also states that pads may be employed instead of rollers for gumming-apparatus.