Patent GB-362983-A (GB)
Title: Improvements in or relating to printing cylinders and design sheets for use therewith
IPC: B41F27/12
Filed: 1930-09-12
Abstract: 362,983. Printing-cylinders. ROBINSON, L. T. A., 5, Arundel Street, Strand, London. Sept. 12, 1930, No. 27318. [Class 100 (ii).] In a longitudinally split printing-cylinder, tensioning of a design sheet which is'superposed on the cylinder is effected by relative tilting or rocking movement of the segments'imparted thereto by a member which'is displaceable longitudinally of the segments: and between separating faces thereof. The displaceable means may comprise a channelshaped wedge 6, Fig. 1, adapted to be displaced in an axial direction between separating faces 4, 5 so as to apply tension to a design sheet 3 overlying cylinder segments 1, 2. Separating faces 7, 8 on the other side of the cylinder axis, which may be disposed in the same plane as the separating faces 4, 5, are adapted to receive the ends of the design sheet. The ends of the design sheet are provided on their inner faces with thin strips 23, 24, or wedgelike strips of metal which are riveted to the respective ends of the sheet, or the sheet ends may be secured to the strips 23,24 by flanged projections formed as by stamping the sheet and clinching over the ends of the projections on the inner faces of the strips 23, 24. The strips 23, 24, which may be bevelled on the inner and outer faces, are disposed in similar shaped recesses 27, 28 which are formed in the separating faces 7, 8 and extend longitudinally the full length of the segments. The cylinder segments 1, 2 are mounted on a shaft 9 which may be formed with five sides ; the sides 10, 11 are at right-angles to the side 12 which may be parallel to the plane of separation of the segments, and the sides 13, 14 form a V-shaped portion, its apex 15 forming a pivotal point about which the segment 1 is adapted to be rocked to apply tension to the design sheet 3. The channel-shaped wedge 6 preferably forms a continuous member extending the full length of the cylinder and is provided with an arcuate inner surface 16 co-operating with a correspondingly shaped surface on the segment 1 as shown. The wedge 6 may be provided with a rectangular projection 21 which tapers from one end of the cylinder to the other and is bored and tapped at each end, or a rectangular projection 21 may be provided at each end of the wedge 6. In the latter case the two end parts are bored and tapped so as to permit of the wedge 6 being displaced longitudinally of the cylinder by suitable set-screws engaging the tapped ends and operable against fixed resistances. The cylinder segments 1, 2 when assembled in position may be retained by end rings which are conically bored to fit over correspondingly cone-shaped projections on the ends of the cylinder segments and secured in place by set-screws which pass through keyhole slots in the rings' and screw into the ends of the segments ; these end rings may form the fixed resistances for the wedge 6.. By removing the set-screws which secure the end rings to the segment 1 the latter can be' rocked, removed, or replaced, and the wedge 6 can be taken out by removing both end rings. In a modification, shown in Fig. 3, a plane-faced wedge 34 is used. The segment 2'is formed with two arcuate faces 35, 36 which are struck from the pivotal point 15. The ends of the design sheet 3 may be connected to strips 23, 24 by rivets or flanged holes in the sheet ends and the strips 23, 24 are placed in recesses formed in faces 40, 41 which are at an angle to the plane of the faces 7, 8. The inclination of the faces 40, 41 serves to decrease the friction on,the strips when closing the segments,' provides a better leading edge for the usual steel doctor to wipe over, and facilitates the entry of the design sheet. In order to prevent entry of ink through the joint or gap 49, Figs. 1, 3, and 4, the gap is closed by a filling material 50 which may consist of asphalt, leather, animal hide, balata, guttapercha, pitch, tar, bitumen, resin, horn in powdered or solid form, or any combination of such materials inserted either as a moulded piece or inserted in a hot condition and then allowed to cool. The outer surface 51 of the insert 50 may be ironed under pressure by hand, as by a hot sad-iron, or mechanically by a hot or cold roller, and burnished. Alternatively, the filling material may be a piece of shaped copper, type-metal, or other metal injected or blown in under pressure when in a fluid or semifluid condition. The filling-piece may be such that it can be superficially charred, hardened, or burnished by the application of heat and pressure ; it may be provided on its outer surface 51 with a coating or thin layer of metal as by dipping, electrodeposition, blowing the metal on, or by compacting a thin sheet of metal with the surface by pressure. In a further form, where the filling material is preferably of a plastic nature so that under pressure it will expand at the entry of the gap 49, the filling- piece may be enclosed wholly or partly in a casing of metal such as sheet copper. When the wedge is moved to tension the design sheet the separating faces carrying the ends of the design sheet move towards each other and abut against the filling material. The wedge 6 may be formed in. two pieces. The design sheet ends may be connected to the strips 23, 24 as described in Specification 363,035.