GB191310795A - Improvements in Stencil Printing Machines. - Google Patents

Abstract

10,795. Bruer, C. May 7. No Patent granted (Sealing fee not paid). Stencilling-apparatus; tripping - arrangements.-In stencil printing-machines of the kind having an endless driving and stencil-carrying device running over rollers and an impression roller which is periodically brought into contact with the material to be printed and moved away therefrom, the endless driving and stencil-carrying device carries a series of projections for operating the sheet-feeding mechanism, and a device adapted to prevent the tripping of the impression roller for a certain period according to the length of sheet to be printed, and may also carry a sheet laying-on bar for use when the automatic feed is inoperative. The stencil is carried by the endless chains 3 passing around the large rollers 1, 2, and the printing is effected by the usual rotary colour band. The top sheet of the pile is fed forward at the proper time by the feeding rollers 13 mounted loosely on the shaft 14 and operated by the lugs 8 on the chain 3 through the toothed wheel 29, bevel gearing, and ratchet clutches on the shaft 14, said clutches allowing the feed rollers to rotate freely on the shaft when the sheet is drawn forward by the bite of the roller 2 and impression roller 7. The sheet stop-bar 20 is slidable vertically on a bracket 22 carried by the pile-support, and is connected by an eye 19, plate 18, and flat bar 17 to the slidable supports 16 of the bearings 15 of the feed-rollers 13, so that as the rollers descend with the feeding away of the pile the sheet stop-bar is maintained level with the top of the pile. The feed rollers are adapted to be raised for positioning a fresh pile by lifting- arms 25 carried on a shaft 24 fitted with a crank handle 27. The mechanism for enabling the machine to print one large sheet or two or more smaller sheets is as follows. The projecting end of the shaft 45 of the large roller 2 carries loosely a four-armed slotted lever 46, which is linked to the shaft of the arm supporting the impression roller 7, is provided with a pivoted switch 44, and is normally maintained in the position shown in Fig. 3 by the spring 53. With the switch in open position as shown in Fig. 3, the projection 9 on the chain misses the slide-surface 57 of the switch, and the cam 43 on the shaft 45 acts on the roller 52 and trips the impression roller at each revolution of the roller 2, thus enabling small sheets of the length of the periphery of the latter roller to be printed. With the switch in the closed position, the projection 9 strikes the surface 57 and displaces the lever 46, whereby the roller 52 is carried out of the path of the cam 43 and prevents the tripping of the impression cylinder, so enabling, supposing the chains to be double the length of the periphery of the main roller, sheets twice as long as the small sheets to be printed. By making the machine higher and arranging for three trips of the roller 7, a longer sheet or three short sheets may be printed during one rotation of the chains.