Patent GB-541215-A (GB)
Title: Improvements in or relating to printing presses
IPC: B41L19/00
Filed: 1940-05-15
Abstract: 541,215. Printing-machines. DAVIDSON, W. W. May 15, 1940, No. 8723. Convention date, May 5, 1939. [Classes 100 (i) and 100 (ii)] A rotary printing-press; which is especially applicable for'general office use by employees not skilled in printing is constructed of a cylinder 20 which is a multiple (twice as shown) of a cylinder 30, the cylinder 20 being fitted with a lithographic printing-plate on its segment 21 and with an impression segment 22, the cylinder 30 being fitted with an offset blanket which receives an impression from the printing-plate at one revolution and prints on offset impression in conjunction with the segment 22 on a sheet fed by automatic mechanism at every revolution of the cylinder 20 at a time when the cylinders 30, 20 are separated by means of co-operating cam surfaces 23, 44. Alternatively, one half of the cylinder 20 may be fitted with a type surface and the cylinder 30 acts as an impression cylinder. The cylinder 30 is mounted in eccentric bearings 31 fitted with spring-controlled arms 32 acted upon by adjustable springs 46 which move the arms towards screws 45, and the cam 23 depresses the cylinder 20 while sheets are fed from a feed table 51 by means of an intermittently rotated piston feed roller 47 co-operating with a retard roller 48 and with intermittently driven feed rollers 55, 56 of which the upper roller is mounted in oscillating levers and the lower roller is mounted on a shaft fitted with registering stops, which front register the sheets while the roller is stationary and act to buckle the sheets. A reciprocating feeler 53 tests the presence of a sheet and, if no sheet is present, acts upon a spring-controlled lever 61, 64 to cause obstruction to the return of the cylinder 30 which in normal operation is returned by the springs 46 to grip the separated sheet between the rollers 20, 30 and so continue to feed and make the' impression. In the case of an offset impression the printed sheet is stripped and guided by a curved member 36 and directed printed side upwards to a delivery table 37. A switch 273 (not shown) prevents the sheets from being carried around by the cylinder 30. The lithographic plate 107 which is held in position by eccentrically mounted clamping. devices is damped by a roller 40 and inked by a roller 41 which are similarly supplied and operated, and are each tripped for part of a revolution by cams on the ends of the cylinder 20, and can be tripped permanently when desired by a cam 184 fitted with an operating-lever, which can be set to trip only the damping rollers or both sets of rollers. The cam 184 acts on eccentrically mounted rollers 188 on lever arms 182 which carry the rollers 40, 41, and which are pivoted to the axle of distributing rollers 186, 187 which are of larger diameter than the applying rollers 40, 41. The supply of ink is taken from a duct roller 216 with a duct blade 220 controlled by a number of screws 221 acting upon rollers 222, Fig. 2. The rollers 40, 41, are supplied by similar oscillating messenger rollers mounted in yokes on levers oscillated by a cam 84 on the shaft 72 of the roller 20. A snaparm 210 pivoted to the machine frame when set in the position shown in Fig. 2 permits of movement of the roller 195 between the rollers 216, 187, but in the position shown in Fig. 16 the roller 195 is maintained permanently in contact with the roller 187, and in this position cleaning of the roller 187 can be effected by means of a flexible blade 287 of synthetic rubber fitted to a tray 280 which can be adjusted laterally on a bar 281, Fig. 16. The blade 287 is of half the width of the roller 187 which is cleaned one half at a time by first applying an ink solvent across one half the width of the roller and subsequently across the other half. The duct roller 216 and the water duct roller 226 are rotated intermittently by ratchets 241, 239 operated by pawls on oscillating levers operated from the same lever 230 which is oscillated by a cam 91 on the shaft 72. The roller 40 is mounted on a shaft provided with an extension 247, Fig. 3 passing through a slot in the frame 70, and the roller can be readily dismounted. The segment 21 on which the printing-plate is mounted is formed with strengthening ribs 104, Fig. 3, and is secured to the end discs 81, 82 of the roller 20 by means of radial bolts 112. The cam discs 91, 92, 83, 84 for the controls are secured on the shaft 22, which is mounted in ball bearings 74, 76. The roller 20 is driven by a belt and pulley and toothed gears from an electric motor, and the roller 30 is driven from the roller 20 by means of an Oldham coupling.