GB815811A - Improvements in printing machines - Google Patents

Abstract

815,811. Printing-machines; feeding sheets. CRABTREE & SONS Ltd., R W. Sept. 30, 1955 [Oct. 1, 1954], No. 28351/54. Classes 100(1) and 100(2) A rotary sheet-fed printing machine comprises printing cylinders mounted in bearings which are movable to carry the cylinders into and out of printing position, hydraulically operated units being coupled to the bearings for their operation, and wherein the supply of hydraulic power to the units is effected through hydraulic transmission lines controlled by valves controlled by a pilot control which includes a preparing device actuated by the response of a sheet detector to the absence of a sheet and a timing device operated in unison with the machine to complete the operation of the pilot control when it has been prepared, so as to cause the various hydraulic control valves for the various units to be tripped in a required sequence by the hydraulic transmission. As shown, an impression cylinder 1 co-operates with blanket cylinders 2, 3, which receive impressions from plate cylinders 4, 5 respectively. Moistening mechanisms 6, 7 and inking mechanisms 8, 9 are associated with the plate cylinders 4, 5 respectively. The blanket cylinders 2, 3 may be tripped automatically from the impression cylinder 1 and plate cylinders 4, 5 by a hydraulic transmission under the control of sheet detectors, not shown, which detect the absence of sheets at a certain point. Tripping is effected; in a predetermined sequence, under the control of a timing valve 23, Fig. 2, driven by the machine through a gear 24. The cylinders 2, 3 are each tripped by double-acting rams and cylinders 10, 11; similarly rams and cylinders 12, 13 trip each inking mechanism. The stroke of the rams is adjustable by worm gearing (Fig. 5, not shown). Pipes 15, 16 and reversing valves 17 are connected to the rams and cylinders 10, 11, 12, 13. In one position of the valves 17, pipes 18, 19 connect the ram cylinders to a pump 20 supplied from a sump 21 and hydraulic accumulator 22, thus holding the rams in a position corresponding to "impression on" or "impression off". The valves 17 are each controlled by a double-acting ram and cylinder connected to pressure and return pipes 25, 26 of a hydraulic circuit including a pump 27 and a change-over valve 28 actuated by a link 29 controlled by a sheet detector, not shown. In the normal position, the valve 28 connects the pipe 25 to a pipe 30 to actuate the appropriate valve 17, such that the cylinders 2, 3 are held in operative position. When pipe 26 is connected to a pipe 31 by the valve 28, the valve 23 subsequently connects pipe 31 to a pipe 32 to actuate valve 17 to trip the cylinders 2, 3. The valve 23, Fig. 4, comprises a shaft 24a carrying the gear 24 and one cam 33 for each valve 17. Each cam operates a valve 35 which connects the pipes 31 and 32 and is adjustable with respect to its shaft to vary the timing of the operation of the valve 35. Each cylinder 2, 3, Fig. 1, is mounted in a pair of eccentric bearings, such that movement of one bearing by the rams and cylinders 10, 11 moves the cylinder 2 or 3 from the cylinder 4 or 5, while the other bearing moves the cylinder 2 or 3 from the cylinder 1. The rams and cylinders 12, 13 trip the rollers of the inking mechanism by a link 47. The moistening mechanisms 6, 7 are actuated through levers 49 and links 50 by the ram and cylinder 12, 13, while the tripping of the sheet feeding. grippers F is effected by a double-acting ram and cylinders 14 which actuates a latch 14' which can prevent gripper operation. Hand-operated valves 51 are provided to trip the cylinders 2, 3 and the inking and moistening mechanisms 8, 9 and 6, 7 other than by the sheet detector. In a modification, the valves 17 (Fig. 8, not shown) are operated by mechanical linkages controlled by a timing device comprising a plurality of cams and actuated by a feeler-controlled rod 54. Specification 747,664 is referred to.