GB763639A - Improvements in or relating to colour printing machines - Google Patents

Abstract

763,639. Printing machines. ABELL G. E. B., TILLEY, D. W., BRICE, P. R., and POWELL, J. A. BENNETT-. March, 31, 1955 [April 6, 1954], No. 10117/54. Class 100(2). [Also in Group XX] A multicolour rotary prin ting machine comprises in dicating means responsive to relative movements betweer two or more of the plate cylinders to show a depar ture of any of the plate cylinders from that axia and angular position relative to one of the cylinders (termed the reference cylinder), in which the impressions of the cylinders will be in correct register, and means are provided for making axial and angular adjustment of the cylinders to obtain correct register. The machine may have plate cylinders 15, 16, Fig. 5 co-operatink with an offset cylinder 12 and plate cylinders 18, 19, co-operating with an offset cylinder 13. The web passes between the offset cylinders and is printed on both sides. The cylinder 16, is the reference cylinder and controls a flashing lamp 41, Fig. 4, positioned in a housing 43 at the line of engagement of the cylinders 12, 13. Light from the lamp 41 is passed through condenser lenses 44 and irises to make a thin beam 50 and is directed towards the cylinders 15, 18, 19. When one of these cylinders is in correct register the corresponding light beam is reflected, by a concave mirror portion 48 carried thereby, along line 51, Fig. 4, and re-enters the housing 43 through suitable openings. Mirrors 45 deflect beams 51 so that they fall on ground-glass screen 46 in the front of the housing. When the plate cylinders are in correct register the beam forms a light spot in the centre of the screen which is provided with right angle lines as shown in Fig. 3 to indicate more exactly any divergence from the true register. If one of of the cylinders 15, 18 or 19 is out of register in an axial direction the light spot will be displaced from the centre in a direction parallel to the light beams 50, 51 and circumferential out or register will displace the light spot at right angles to this direction. Corrections are made by displacing the plate cylinder angularly relative to its driving gear or axially relative to the frame as described below. The lamp 41 is a flash-tube giving a flash of short duration and it may be arranged to flash a number, say eight times during each revolution of cylinder 16 and a corresponding number of mirrors may be arranged on the peripheries of the cylinders 15, 18, 19, so that light spots appear more frequently on the screen. This may be effected by a cam actuated contact associated with the cylinder 16, supplying the flashtube 41 through a series of eight slip rings connected to a selector switch so that any number of the mirrors 48 may be selected to throw an intermittent spot on the screen. The screen may be provided with equal quadrants of photoelectric material so that when the lightspot is displaced from the centre one or two of the quadrants receive light and actuate a visual and audible alarm. The mirrors may constitute suitably coated depressions formed in the surface of the cylinder. Cylinders tripping and adjusting:-As shown in Fig. 2, each cylinder (except offset cylinder 12) is mounted in a pair of eccentric sleeves 31 which are rotatable in unison by limbs 36 to move the cylinders into and out of engagement with their coacting cylinders. The shaft 26 at one end is carried by a ball bearing 28 held in a housing 38 displaceable axially of the sleeve 31 by a worm 40 co-operating with threads 39 on the housing. The worm may be rotated manually or otherwise to shift the housing in the sleeve. The shaft 27 at the other end is mounted in a housing slidable axially of the eccentric sleeve 31 and loaded by springs 30 towards the other bearing end 26. Rotation of worm 40 therefore moves the cylinder axially. The driving gar 58 is connected to the cylinder hub 20 by screws 59 passing through arcuate slots in the gear so that the angular position of the gear may be adjusted. The hub 20 may be a shallow tapering cone, the inner surface 22 of the shell 21 being adapted to fit on it. The outer surface of the shell carries a printing surface or a resilient blanket 23 depending on whether it is a plate cylinder or an offset cylinder. Alternatively the boss 20 may be parallel sided and the sleeve 21 may be shrunk in place.