Apparatus and method for oscillating the form rollers in a printing press

Abstract

An apparatus and method for oscillating the ink form rollers and dampening form roller in a lithographic printing press to apply a smooth, relatively uniform coating of ink to the ink-receptive areas of the lithographic printing plate and to prevent ink from being transferred from the dampening form roller to the ink-rejecting areas of the printing plate. The ink form rollers and the dampening form roller are each mounted on a shaft rotatable about its own axis. The shaft has at least one shaft key for mating with a complementary keyway in a bushing which is inserted at least partially into the central opening of the corresponding roller. The engagement between the shaft key and the bushing keyway allows the roller and bushing to engage the shaft for common rotation while permitting the roller and bushing to slide axially with resepct to the shaft. First and second collar members may be disposed at respective predetermined locations on the corresponding shaft for limiting the axial movement of the corresponding roller between selected limits, although both the ink form rollers and the dampening form roller are preferably allowed to oscillate axially substantially the same distance in each direction as the corresponding vibrating roller by which the oscillating motion is imparted thereto.