GB621144A - Improvements in or relating to a perfecting offset press - Google Patents

Abstract

621,144. Rotary offset printing-machines. HARRIS-SEYBOLD CO. July 12, 1946, Nos. 20895 and 20896. Convention dates, July 13, 1945. [Class 100 (ii)] A perfecting offset press has two printing units arranged side-by-side, each comprising plate, offset and impression cylinders 23, 22, 21 and corresponding cylinders 27, 26, 25 rotating in the opposite direction, inking mechanisms 30, 31 situated above the plate cylinders, sheet conveying devices, such as transfer cylinders 50, 51, conveying sheets partly around each impression cylinder, the sheets travelling in a path lying between the plate cylinders, partly above one and partly below the other, the layout of the machine being such that the offset cylinders in each unit are disposed on opposite sides of the press and outward of the impression cylinders, and that the offset cylinders are outermost in each unit, whereby easy access is obtained to the plate and offset cylinders for operators standing on the outside of each unit. Sheets are fed from a pile 11 over a table 40, 41, and associated travelling belts 44, 45 to transfer - cylinders 17, 18, and from cylinder 18 the sheets are taken by the impression cylinder 21, which carries them past the first offset cylinder 22. The sheets then travel to impression cylinder 25 of the other unit and are printed on the other side by offset cylinder 26 and are finally taken by a stripper cylinder 34 delivering the sheets to a travelling band 54 travelling below an operator's table 39 to a delivery stack 38. The two units are synchronized, and the layout of the machine and the hinging of the tables 40, 41 gives access simultaneously to large areas of both plate and offset cylinders. In modifications, Fig. 1 (not shown), the machine has two additional cylinders transferring the sheets from one impression cylinder to the other; in Fig. 3 (not shown), the sheets are fed from below the impression cylinders and delivered upwardly between the two units, the plate cylinders are vertically above the offset cylinders, the impression cylinders being disposed centrally and below the offset cylinders, and the feed cylinder is below the impression cylinders but towards the outer side of the machine, and in Fig. 4 (not shown) feed is from below and the impression cylinders are of double size with'two sets of grippers each holding one sheet.