Patent GB-694012-A (GB)
Title: Improvements in or relating to a sheet printing apparatus
IPC: B41F21/00
Filed: 1951-08-30
Abstract: 694,012. Printing-machines. ADDRESSOGRAPH-MULTIGRAPH CORPORATION. Aug. 30, 1951, [Feb. 17, 1951; June 1, 1951], No. 20544/51. Class 100(ii) A printing machine for printing on both sides of a sheet comprises a pair of horizontally spaced printing couples A, B, each including a printing cylinder 20 and a pressure cylinder 21 coacting therewith and a sheet receptacle 16 there being feed roller means to receive the printed sheets from the first printing couple A turn them over and forward them to the receptacle, and means to eject the sheets from the receptacle and feed them to the second printing couple B to print on the other side. The sheets are fed into the first printing couple A over a table 33 and are accurately positioned with respect to the printing cylinder by a stop finger 30 and a feed roller 34. A cam 37 on the printing cylinder engages a follower 38 to turn a bracket 36 so that a roller 32 carried thereon moves into co-operation with the feed roller 34 and the stop finger 30 is displaced beneath the level of the table. By this means the sheet fed to the table 33 is simultaneously released by the stop and gripped against the feed roller 34 for advancement between the printing and pressure cylinders 20, 21. Emerging from the first printing couple the sheet passes under a roller 59, carried on an arm 57 and spring loaded against the cylinder 21, on to a table 50 and between rollers 51, 52. Rollers 52 are carried at the other end of arms 57 and rest on the feed roller 51 which is driven from the pressure cylinder 21 by a gear 54. Hooked on the spindle 56 of rollers 52 are plates 63 carrying a series of rollers 62 adapted to bear with spring pressure against the underside of roller 51. The plates are shaped at 69 so that a sheet passing between rollers 51, 52 is bent round roller 51 and fed upside down by rollers 51, 62 into the receptacle which lies under the first printing couple. The receptacle comprises a slotted bottom wall 70, a slotted upper wall 80 and a slidably mounted ejector 90 halving fingers 97 passing through slots in the upper and lower walls to close the lower end of the receptacle. The ejector is mounted on guide rods 91, 95 and drawn upwardly to eject the sheet by springs 111. A cam 100 driven from the pressure cylinder acts through arms 104, 106 to move the ejector downwardly against springs 111 to allow a sheet to enter the receptacle. Pivoted tines 135, the position of which is controlled by a cam 138, are moved from the upper position (shown) where they allow a sheet to enter the receptacle to a lower position where they deflect a sheet ejected from the receptacle between the feed rollers 115, 116. The roller 115 forms a pulley for a conveyer belt 125 passing, at the other end, over a roller 126 adjacent the second printing couple and adapted to feed the sheets to the feed table 33 thereon. A sheet positioning and feeding means as described above is provided for the second printing couple B. The printing couples and feed rollers are synchronously driven from an electric motor 18 by chains 22, 24. To adapt the apparatus for varying sizes of sheet the stroke of the ejector may be varied by a screw 162. The apparatus may be adapted for printing in two colours on the same side of the sheet by unhooking and removing the plates 63 and rollers 51 so that the sheets are no longer turned over and fed to the receptacles but are fed directly on to the conveyer belt 125. Specification 499,800 is referred to.