Patent GB-550523-A (GB)
Title: Improvements in or relating to printing presses
IPC: B41L19/00
Filed: 1941-03-14
Abstract: 550,523. Printing-machines; feeding and delivering sheets. DAVIDSON, W. W. March 14, 1941, No. 3544. Convention date, March 18, 1940. [Classes 100 (i) and 100 (ii)] A rotary printing-machine is constructed with a cylinder 13, Fig. 1, which acts either as an impression or offset cylinder in coaction with a cylinder 12 of twice the diameter which can be fitted with a lithographic plate 20 co-operating with damping rollers 22 and inking rollers 23, and with an impression plate 21, or the cylinder 12 can be fitted with a typographic printing-surface co-operating with an impression blanket on the cylinder 13. The machine thus prints the upper side of a fed sheet with a typographic impression, or the lower side with an offset lithographic impression and the printed sheet in either case is delivered printed side up either into a box 67 or to an automatically lowered table. The sheets are fed by a conveyor 16 and side guide 91, to front stops 92 associated with dropping rollers 93, 94 of which the lower roller is driven by a camactuated gear 95 and advances the sheets so that at the time they reach grippers 36, Fig. 5, which are carried by sprocket chains 31 the sheets are travelling slightly faster than the grippers. The links of the chains have a seating engagement with the sprockets 32, 35. The grippers are fitted with curved registering stops 39, and owing to the faster rate of the sheets they buckle slightly when the stop is engaged. The gripper members 36 are carried by collars 49 adjustably secured to a rod 46 which is oscillated to open the grippers for receiving sheets by a lever arm 58 engaging a cam 62, and for delivery the grippers are opened by a cam 63 for delivering a sheet printed by the offset method. A stripping device 73 co-operates with the cam 63 to strip the sheet and cause it to be reversed so as to be delivered printed side up. The grippers 36 are freely'mounted and are pressed against the sheet by the action of springs 54 when the rod 46 is moved counterclockwise sufficiently far to move the surface 53 of a notch away from the face of the normally contacting gripper. The sheets are thus pressed with a pressure independent of the rotation of the rod 46. Some of the grippers are fitted with extra springs to ensure a good grip of the sheet so as to strip the sheet readily from the offset blanket. The chains 31 are driven by the sprocket 32, mounted on the shaft of the roller 13, and the sprocket 35 arranged below the sprocket 32 and at such distance therefrom that the grippers travel a distance equal to twice the diameter of the roller 13. The grippers are arranged so as not to contact with the roller 12. When typographic printing occurs the grippers are opened by a removable cam arranged below rollers 69, Fig. 1, which engage the margins of the sheets in conjunction with lower rollers of the sprocket shaft 71. This cam and the rollers 69 are put out of action when offset printing takes place. A chain guide plate 83 prevents flexing of the chain during action of the cam 63. Specification 550,413 is referred to.