Internal worm drive and oscillating roller assembly for use in inking

Abstract

An internal worm drive has a worm gear and a substantially hollow tubular worm with an outer surface and an inner surface. The inner surface has at least one internal worm thread mating the worm gear. The axis of the worm gear is substantially perpendicular to the longitudinal axis of the tubular worm. Utilizing the tubular worm with the threaded internal surface in conjunction with the mating worm gear is an oscillating roller assembly suitable for use as an ink roller in lithographic presses. The oscillating roller assembly has a shaft, and a bearing unit mounted along the shaft. A worm gear having a plurality of teeth is contained in a slotted space in the bearing unit and the shaft such that the rotational axis of the worm gear is substantially perpendicular to the longitudinal axis of the bearing unit and the shaft. The slotted space has first and second opposite longitudinal ends within the shaft. A pair of substantially coaxial eccentric cams are integrally affixed to opposite surfaces of the worm gear. The cams alternately engage the shaft at the opposite ends of the slotted space. A roller shell having at least one internal thread is circumferentially mounted around the bearing unit such that its internal thread engages the teeth of the worm gear. Rotation of the roller shell causes the worm gear to rotate, thereby causing the cams to alternately engage the shaft at the opposite ends of the slotted space, thereby causing the bearing unit and roller shell to oscillate back and forth along the shaft.