GB846836A - Improvements relating to offset printing machines - Google Patents

Abstract

846,836. Printing-machines. ADDRESSOGRAPH-MULTIGRAPH CORPORATION. Jan. 22, 1959 [Feb. 13, 1958], No. 2404/59. Class 100(2) A rotary offset lithographic printing- machine includes a line selector device comprising an axially slidable member mounted on the blanket cylinder carrying a clamp for a thin, flexible mask to prevent printing from a portion of the blanket, index means on the blanket cylinder for indicating the position of the mask, and index means on a sheet feed table for enabling the alignment of a sheet with the masked and unmasked portions of the blanket. The mask M is clamped between plates 41a, 41b hinged on a spindle 42, pointed pins on the plate 41a engaging holes in the plate 41b. The plate 41 is fixed to a panel 43 of a Z-shaped bracket 45, a shelf 44 of which is formed with handles 58. The bracket 45 is slidable along a rail 46 secured by screws 62 to the leading end blanket clamp 54b of the blanket cylinder 26. The bracket 45 is held against the rail 46 and the plates 41a, 41b held together by springs surrounding bolts 47, squaresection portions of which run in an axial slot 51 in the rail. A catch 65 on the plate 41a engages in notches 66 in the rail 46. To adjust the mask, the handles 56 are raised slightly to release the catch 65, and the bracket 45 is moved manually axially by means of the handles, a pointer 50 co-operating with a line-indicator scale 59 secured to the trailing end blanket clamp 54a. Sheets 120 are fed from a table 28 carrying an equivalent scale 64. For printing from a complete master sheet, the mask is removed, the clamp being opened by the handles. When it is required to print repetitive and some variable data, the latter is printed first. All sheets to receive the first line of variable data are first fed, in correct alignment by reference to the scale 64, in turn, so that their lower edges (left edges in feed direction) are aligned with the bottom of the desired line, while the mask covers only the repetitive data. The mask is then moved to cover the first variable line while the second is printed, and so on. In every case, the printed matter is limited on one side by the mask and on the other by the edge of the copy sheet. The variable data portion of the master sheet is then removed, as by tearing along a line of perforations, from the forme cylinder, and an ink image again transferred to the blanket 55, all the sheets being printed with the repetitive data. Alternatively, the variable data part of the master sheet can be overlaid, or may be spaced so far from the repetitive data part as to avoid reproduction on to the sheets. An alternative form of clamp, wherein the slide member is U-shaped to engage round the rail, and is attached by an angle bracket to the plate 41b, the pins and holes on the plates 41a, 41b being omitted, is described, and illustrated in Fig. 9 (not shown). Specification 633,747 is referred to.