Patent GB-200294-A (GB)
Title: Improvements in multicolor printing machines
IPC: B41F7/08
Filed: 1922-05-17
Abstract: 200,294. Barker, R. W., (American Bank Note Co.). May 17, 1922. Offset machines ; tripping-arrangements.-A rotary offset machine for printing negotiable forms &c. in several colours not superposed comprises an offset cylinder formed with two offset blankets and a number of relief printing-cylinders which rotate twice to each revolution of the offset cylinder. The offset cylinder coacts with an impression cylinder which may be arranged to print on one side only of a sheet in conjunction with a single offset blanket on the offset cylinder. In some cases alternate sheets may be printed differently from separate offset blankets on the offset cylinder, or the impression cylinder may also be fitted with an offset blanket and perfected impressions obtained by one passage of a sheet through the machine, the offset blanket of the impression cylinder receiving its design from one of the blankets of the main offset cylinder or from a separate printing cylinder not associated with this cylinder. The colours from several ducts may be supplied to each printing-cylinder, and these colours may be blended as desired by adjustable mechanism which permits the blending to be varied. Improvements are described in the inking-mechanism, and the means for controlling the tripping of the printing-cylinders, which can be arranged to permit these cylinders to be tripped collectively or individually. As shown in Fig. 2, an offset cylinder 20 is fitted with two blankets 21, 22 with which coact printing-cylinders 25, 26, 27, 28, and the impression cylinder 23 is fitted with an offset blanket 24 which can receive designs from one of the blankets 21, 22, or from a printing-cylinder 113. Inking-apparatus A, B, C, D, E is employed to ink the formes, and the sheets are fed over a table formed of two pivoted parts 245, 246, Fig. 3, which can be raised by means of a wheel 251 and worm gearing to the position shown in dotted lines to give access to the printing-couples for make-ready. A cam 252 on the underside of section 246 and a, fixed stud 253 assist the folding action. The printing-cylinders 25, 28 are mounted in spring-pressed bearings 31, 35, 37, Fig. 4, the springs tending to move the cylinders away from printing position, and eccentrics 40, 41, 42, 43 may be operated to move the cylinders into printing position. These eccentrics may be operated by mechanism controlled by cams 48, 62, 76, 90 to bring each cylinder into contact with one offset blanket, and to trip the cylinder while the other blanket is passing, or by means of setting-plates 50, 64, 78, 92 all the cylinders may be caused to remain in printing position. As shown in Fig. 6, the plate 64 is set to cause the cylinder 26 to be tripped for each semirevolution of cylinder 20, the cylinder 26 being moved from the position shown when lever 63 is rotated counter-clockwise by cam 62, a thrust plate 66 on the plate 64 transmitting motion to a pin 61 on lever 59 connected by a link 60 to a crank on the eccentric 41. The plate 64 can be set by a spider arm 119, which also controls the other plates, by means of flexible link connections. The flexible connections operate bellcranks, as 68, which by a pin-and-slot connection move the plates, as 64, in a counter-clockwise direction, when the plate 66 is to be moved out oi the path of the pin 61 and the cylinder 26 is to remain in printing operation continuously. A number of dogs, as 71, are provided which are independently operated by hand to hold the bellcrank 68 and plate 64 in the position in which they cause the cylinder to be out of operation. The spider 119 is operated by a rod 137 and crankshaft 138 operated by a handle, or by a pedaloperated lever 142 and a rack-and-pinion. The cams 48 may be set in positions at 180‹ to those shown to alter the timing of the printing operations. The impression cylinder 23 and its associated printing-cylinder 113 may be mounted similarly to the cylinders 25, 26, and they are moved to printing position by eccentrics 39, 116, operated by links from a plate 100 which is oscillated by a thrust member 106 reciprocated by cam mechanism. The member 106 is controlled by a lever 133 connected to the spider 119, or it may be controlled by a hand-operated shaft 145 connected to it by cranks and links. The cylinder 28 is mounted in a frame which can be withdrawn by screws to permit of access to cylinder 20. To facilitate register of the designs. the cylinders are adjustably mounted on their axles. The cylinders are mounted in housings so as to be axially adjustable therein by screws passing through bridge-pieces integral with the housings and bearing upon the ends of the cylinder shafts. Inking-apparatus.-The inking-rollers for each of the cylinders 25 - - 28, Fig. 2, are similar, and comprise two or three ink founts 149, 150, 151, Figs. 2 and 13, from which ink is transferred by oscillating frames carrying messenger rolls 178, 179, 184, fitted with ink-cutting rolls 180, 181, 184. The fount rollers are rotated intermittingly by ratchet-and.pawl mechanism, and the messenger rollers deliver the ink in stripes which register exactly to rollers 174. If three founts are used, stripes of three colours are transferred to the rollers 174 from sectional rollers in the founts. From the rollers 174 the ink is distributed and applied by means of rollers 175, 176, 177, 172, 173, 171, 170, 169, these rollers being so arranged that the rollers 169 are of composition, the rollers 170, 171 are of metal and all the other rolls are alternately composition and metal rollers. The metal rollers are positively driven and the others frictionally. When it is desired to blend the stripes of the different colours the rollers 170, 171, 177 are given axial reciprocating motions by means of a rocking lever 192, Fig. 13, which is formed with shoes 193 engaging grooved pulleys 194 on the axles of the rollers 170, 171. The lever 192 is operated by a bell-crank 199, link 202, and an adjustable crank-pin, which can be moved axially to vary the amount of blending and to reduce it to zero if no blending is required. A direct lever between rolls 170, and 177 causes the roller 177 to reciprocate to the same extent as roller 170 but in an opposite direction. The rollers 178, 179, are mounted in oscillating frames 210, 211, Fig. 13, operated by levers and adjustable screws from a cam 222 on the shaft of the roller 174. A projection 227 on frame 210 trips the fountainroll actuating-pawl when the frame 210 is trippsd. The frames 210, 211, and a similar one for the third fountain may be tripped automatically when the associated printing-roller is tripped by means of a link 236, Fig. 4, operated by the eccentric shaft of the cylinder trip mechanism. The link 236 operates, by means of lever-and-link mechanism, a swinging cam 229 which trips the frames 210, 211. This mechanism may be hand operated when it is desired to trip the inking- supply rollers independently of the tripping of the cylinders. The inking-mechanisms A, B are mounted in frames which are independently adjustable by hand-wheels, and the inking- mechanism E is mounted in a frame angularly adjustable by worm gearing.