Bogenrotationsdruckmaschine

735,477. Printing machines. MILLER PRINTING MACHINERY CO. March 10, 1953 [March 18, 1952], No. 6554/53. Classes 100 (1) and 100 (2). Sheet-transferring arrangements.-A sheet-fed rotary printing machine comprises a first printing unit 10, Fig. 2, for printing a first impression on a sheet S, a second printing unit 11 for printing a second impression on the sheet, and a series of three co-operating transfer cylinders T1, T2, T3 connecting the printing units 10, 11 and having cam-actuated grippers adapted to carry a sheet from the first unit 10 where it is printed on one side and selectively to transfer it to the second unit 11 with either the same side or the reverse side presented for printing. The machine operates as a " twocolour machine when the sheet is printed twice on the same side and as a " perfecting " machine when the sheet is printed on opposite sides. Fig. 2 shows the machine operating as a two-colour machine. The sheet S is fed to a feed table 13 from which it is taken by a forwarding cylinder 14, the gripper G1 of which grips the leading end a of the sheet and transfers it to the gripper G2 of the impression cylinder I1. The sheet is printed (at 30) as it passes round the impression cylinder by an offset cylinder 18 co-operating with a forme cylinder 17 inked by rolls 16. From the impression cylinder I1, the sheet is taken by the gripper G3 of the first transfer cylinder T1 and transferred at the common tangent point t2 to the gripper G5 or G4 of the second transfer cylinder T2. For " two-colour " operation, the leading edge a is transferred by gripper G5 (or G4) to gripper G6 of the third transfer cylinder T3 whence it is taken by the gripper G8 of the impression cylinder I2 of the second unit 11. The second unit which comprises an offset cylinder 24, a forme cylinder 25 and inking rolls 28 prints the sheet at 31 on the same side as the impression 30 of the unit 10. The printed sheet is delivered by a delivery cylinder 32. The second transfer cylinder has a diameter twice that of the associated cylinders so that two sheets may be carried by it at the same time, which provision is necessitated by-the arrangements for " perfecting " now to be described with reference to Fig. 3. The sheet S printed at 30 is passed from the transfer cylinder T1 to the gripper G4 or G5 of transfer cylinder T2 as described for two-colour operation, but instead of the leading edge a being transferred to the gripper G6, the trailing edge b of the sheet is transferred