GB845443A - Damping or repellent system for lithographic duplicators or printing machines - Google Patents

Abstract

845,443. Printing machines. DICK CO., A. B. April 10, 1957 [April 26, 1956], No. 11757/57. Class 100(2) In a lithographic printing machine, ink repellent is removed from a fountain 56 by a fountain roller 58 and transferred to a pivotally mounted transfer roller 64 which may be engaged with or disengaged from a roller 40 of a roller train connected with the plate cylinder by means of an oscillating mechanism, the cyclical speed of the oscillating mechanism differing slightly from the cyclical speed of the plate cylinder so that recurrence of the same relative positions of said oscillating mechanism and said cylinder happens only at large intervals. The greater part of the repellent-feeding system is mounted on a sub-frame 44 detachable from the main machine frame, and in which is formed the repellent fountain 56 fed by a reservoir of the inverted bottle-feeder type. The fountain roller 58 is journalled in the sub-frame 44 and may be driven at the peripheral speed of the plate cylinder. Pivoted co-axially with the roller 58 is a carriage 68 which supports the transfer roller 64 in bearings which are slidable in slots 68a and biassed towards the fountain roller by springs 70. A spring 76 continuously biasses the carriage 68 into a position where the roller 64 contacts the roller 40. The carriage 68 is oscillated by levers 78 pivoted at 100 to the main machine frame. The lower arm 96 of each lever 78 carries a roller 94 which is held in contact with a cam 86 by a spring 98. The cam 86 is provided with a gear 90 which meshes with a slightly smaller gear 92 secured to the plate cylinder. The upper arm 80 of the lever 78 carries a roller 82 which engages a lug 84 on the carriage 68 so that, as shown in Fig. 7, when the lever is oscillated by the cam 86 the carriage is swung to and fro about its pivot bringing the roller 64 alternately into and out of contact with the roller 40. The pivots 100 for the levers 78 are mounted eccentrically on a shaft 102 so that by rotating the shaft the levers may be brought closer to or further away from the carriage 68; when the lever is at its closest to the carriage its action is such that the transfer roller 64 is at all times held out of contact with the roller 40; when the lever is at its furthest away it has so much lost motion that the roller 64 is in continuous contact with the roller 40. Between these extremes the length of the periods of contact between the two rollers is infinitely variable by rotation of the shaft 102. The relation of the gears 90, 92 ensures an even distribution of repellent on the plate cylinder when the contact between the rollers 64, 40 is intermittent. The roller 64 may be swung out of contact with the roller 40 as shown in Fig. 4, e.g. when the machine is out of service, by cams 120 which are controlled by a lever 116 and act on follower rollers 122 on the carriage 68. At the same time arms 130 pivoted to the carriage at 132 abut against a stop 136 on the sub-frame 44 and the edges 138 on the arms engage the bearings 69 and push the roller 64 out of contact with the fountain roller 58 against the influence of the springs 70. During operation the levers 78 do not swing the carriage 68 far enough to bring the arms 130 into action. The roller 40 engages a frame roller 36 (Fig. 1 not shown) through which repellent is applied to the plate cylinder The roller 36 also applies ink to the plate cylinder and the roller 40 may be oscillated axially to help spread the ink. Specification 845,444 is referred to.