Patent GB-710337-A (GB)
Title: Improvements in or relating to rotary printing or duplicating machines
Inventor: MOON WILLIAM RICHARD HARDING
IPC: B41L19/00
Filed: 1950-04-26
Abstract: 710,337. Printing-machines; feeding sheets. ADREMA, Ltd. July 26, 1951 [April 26, 1950], No. 10285/50. Classes 100 (1) and 100 (2) Feelers; tripping arrangements.-In a printing or duplicating machine a printing cylinder and an impression cylinder rotating about movable parallel axes are spring-urged apart and at a certain point in the printing cycle, are moved together for the printing operation, means being provided to detect the absence of a sheet for printing and to cause the printing and impression cylinders to separate again before the beginning of the printing operations thereby to avoid dirtying the impression surface. As shown in Fig. 6, the impression surface 40 extends only part way round the periphery of the cvlinder 11. The printing surface which is a ribbon inked embossed sheet metal surface is similarly arranged on the printing cylinder. The impression cylinder is mounted on an axle 10, Fig. 1, driven e g. from the main drive shaft of an addressing machine so as to operate in synchronism therewith. The printing cylinder is mounted on an axle 27 carried by a pair of eccentrics 29 rotatable to move the axles 10, 27 towards and away from each other by screwed rods 33 one connected to each eccentric and each connected to a lever 31 on a common shaft 32. At one end, as shown in Fig. 1, the lever 31 has another arm 31a carrying a cam follower roller 45 and extended for attachment to a spring 30 tending to turn the lever 31 to separate the cyinders. A cam 44 carried on the end of the driving shaft is adapted to displace the lever 31 to move the cylinders together. A gear wheel 25, Fig. 4, on the impression cylinder 11 meshes with a similar gear wheel 26 on the printing cylinder 28 which is driven thereby at the same speed as the impression cylinder. A second cam 47, Fig. 1, on the axle 10 actuates a push rod 48 connected to a short lever 51 loosely pivoted on a shaft 52 and carrying an abutment shoulder 55. Secured to the shaft 52 is a second lever 53 connected to a link 56 slotted at its lower end to engage a pin on a pivoted detent lever 58 normally he'd against a stop pin 61 by a spring 62. The shaft 52 is extended over the length of the printing cylinder and carries a number of feelers 57, Fig. 4, which, at the beginning of each printing cycle are moved towards the support plate for the incoming sheets for printing. In the absence of a sheet the feelers pass beyond the point at which they would normally be arrested by the paper, and enter openings in the support. A spring 50, Fig. 1, normally rotates the lever 51 so that the shoulder 55 abuts a pin 54 to rotate the lever 53 against the action of a weaker spring 60 which tends to turn the feelers 57 into engagement with the surface of the paper. When the cam 47 moves the lever 51 to the position shown rotation of lever 53 under the action of spring 60 is prevented only by the contact with the feelers 57 and the sheet of paper ready for printing. Should the paper be absent the shaft 52 and lever 53 rotate beyond the point shown in Fig. 1, and cause the link 56 to move downwardly and tilt the detent about its pivot 59. The cam 44, having displaced the lever 31 to move the cylinders together, moves past the roller 45 and leaves the lever free to turn under the action of spring 30 to separate the cylinders again. In the absence of a sheet for printing, this separation would take p'ace in the printing cycle before the printing and impression surfaces came into contact, but separation is normally prevented by the abutment between the end of detent 58 and a pin 63 on the lever arm 31a. When there is no sheet of paper presented for printing the detent 58 is tilted as described above so that its end lies out of the path of pin 63 and is therefore ineffective to retain the lever 31 so that the cylinders separate. Feeding sheets.-The incoming sheet of paper is advanced by feed rollers 71, 72, Fig. 4, through a gate 43 so that its end engages three pins 93, Fig. 6, projecting into apertures in the cylinder 11 and attached to gripper jaws 91 pivoted on a shaft 92 controlled by an arm carrying a roller following a cam fixed to the side plate of the machine so that the jaws 91 move to and from the clamping position at predetermined points in each printing cycle. The feed rollers 71, 72 are arranged to separate at a fixed point in each printing cycle as described below, the arrangement being such that the paper buckles slightly as it contacts the pins 93, the jaws close on the edge of the paper and the rollers 71, 72 open to free the paper. The paper sheets are fed into an input channel formed by upper and lower fixed guide plates 64, 65. The gate 43 extends the full width of the channel and is carried on a pair of brackets 67 fast to a shaft 68 which is rotatable to open or close the gate. The feed rollers 71, 72 are of rubber and independently driven from the gear wheel 26 on the printing cylinder, the lower ones 72 being mounted on an axle 74 movably carried on a pair of brackets 75 loaded by torsion springs to bring the rollers together. Projections 67a on the gate supporting brackets bear down on the axle 74 to control the position of the rollers 72. The shaft 68 is controlled to open and close the gate 43 and simultaneously to close and separate the rollers 71, 72 by a mechanism shown in Fig. 1, and consisting of a lever 82 on the end of the shaft connected by a link 83 to one arm of a bellcrank lever 84, the other arm of which has a roller 85 following a cam on axle 10 formed by relatively adjustable cam parts 86, 87. The lever is urged by a spring 88 in a direction to open the gate and close the rollers but for nearly half of each rotation is held by the cam part 86 in the position in which the gate is closed and the rollers are separated so that a sheet fed to the input channel will be prevented from entering the printing machine. This is followed by a fall in the cam which causes the gate to open and the rollers to close to grip and advance the sheet into printing position where it is gripped by the gripper 91 as described above. The cam part 87 is slightly higher and causes the gate to close slightly and the rollers to separate so that the sheet may be controlled entirely by the printing cylinders during the printing operation. When the detent lever 58 tilts as a result of the feelers having detected the absence of a sheet for printing, an abutment 89 thereon moves in the path of an abutment 90 on the lever 84 which is prevented thereby from movement so the gate does not open nor do the rollers 71, 72 close A slidable ram 101, Fig. 4, actuated by a cam 99 on shaft 10 is adapted to actuate a conveyer device described in Specification 710,336.