Patent GB-644102-A (GB)
Title: Improvements in printing machines
IPC: B41F3/20
Filed: 1948-01-22
Abstract: 644,102. Printing-machines. COOK, E. R. Jan. 22, 1948, No. 1988. [Class 100 (ii)] In a printing-machine in which one or more impression cylinders 9, 9a are carried at their ends by endless travelling elements, e.g. sprocket chains by which the axes of the cylinders are caused to move in an orbit within which a stationary type bed is mounted, the cylinders are guided by a pair of complementary continuous tracks 5, 6 at each side of the machine and the cylinders are rotated by rollers 18 engaging with a fixed driving track 17 corresponding in shape to and spaced from each continuous guide track 5, 6. The machine comprises main frame side plates 1 braced by struts 2 and embraces a sub-frame assembly, held by flanged bolts 3 to the side plates, and which carries the stationary type bed 4 and also the guide tracks 5 and 6 one pair at each side of the bed 4. Spaced from the guide tracks 5 by bolts 8 are the fixed driving tracks 17 formed by teeth in plates 7 or comprising an endless fixed chain 17 which engages and causes to rotate the rollers 18 shown as sprocket wheels secured on the cylinder shaft drawn over the fixed chain 17 by links 25 attached to travelling chains 19. The cylinders 9, 9a have grippers to pick up and release the paper sheets. The travelling chains 19, one of which is positioned at each side of the machine, are driven by sprocket wheels 20 on a driven shaft 22. Shaft 22 carries a roller which transfers ink to rollers 10, 10a, situated between the impression cylinders and similarly drawn by links 28 attached to the travelling chains 19. The impression cylinders are held away from contact with the transfer roller by the portion 5a, 6a, Fig. 4, of the tracks 5, 6 while the inking rollers travel in the portion 5b, 6b enabling them to contact the 'transfer rollers. The tracks 5, 6 also guide the impression rollers into engagement with the bed 4, the axial alignment of the impression cylinders being effected by rollers 15 on the ends of the impression cylinder spindles which engage rails 13 inwardly projecting from the side plates 1. For two colour work two type beds may be arranged in series with ramps fitted in the guides so that the rollers contact only their corresponding type bed. The transfer roller 29, Fig. 5, over which the inking-rollers 10, 10a pass, is supplied with ink by a supply roller 32 mounted on an arm 33 oscillated by a rod 36 from a cam mechanism 38-41 driven from the machine and synchronized therewith so that the arm swings towards the roller 29 before the rollers 10, 10a reach it. In the other direction of swing, the roller 32 contacts a doctor roller 44 which revolves in an ink duct, and at each swing an extension 50 of the arm 33 engages an arm 47 so as to push it anticlockwise and a pawl 48 thereon engages a ratchet wheel 49 which rotates the roller 44 one step. In a modification the inking mechanism comprises an ink slab situated inside or outside the path of the cylinders 10, 10a and the inking rollers 9, 9a contact the slab as they pass either by the force of gravity or by spring action. To enable the inking rollers to be coated with ink before printing is commenced and without the type being inked a forme chase 55, Fig. 3, on the type bed is normally displaced from the path of cylinders 9, 9a and rollers 10, 10a by means of springs 66 mounted on a series of pins 65 screwed to the chase and which extend through the type bed 4. The chase is moved into operative position by a hand lever which through parallel linkage moves four wedges 57 to engage in slots in lugs 56 depending from the chase 55 which is thereby moved, against the pressure of springs 66, towards fixed stops 67 to render the inking roller effective.