Patent GB-755972-A (GB)
Title: Improvements in or relating to colour supply devices for rotating stencil printers
IPC: B41L13/18
Filed: 1953-12-07
Abstract: 755,972. Inking-apparatus. GEHA-WERKE GES. Dec. 7, 1953 [Dec. 8, 1952; Aug. 27, 1953], No. 34016/53. Class 100 (2). In an ink-supply device for a rotary stencil duplicator, ink under pressure is deposited as a stroke or row of dots extending parallel to the axis of the stencil drum; the applicator consists of two or more concentric tubes arranged across the machine, each tube having apertures which may be adjusted to one another by rotation of one of the tubes or one of the outer two, one tube (e.g. the outer) having two or more rows of holes or slots while the other (e.g. the inner or the inner of the outer two) has a single linear row of holes or slots spaced correspondingly to those of the one tube; one of the rows in the one tube is helical so that a particular part of the row may be brought into coincidence with the linear row in the other tube to apply extra ink in a narrow band as required; a clogged hole may also be cleared in this way as the full pressure of the ink-supply pump may be concentrated on a single hole or on a very few holes. As applied to a two-drum machine in which the stencil is mounted on an endless colour cloth running over the drums, and in which ink directed on to the lower drum by the concentric tubes 17, 18, Fig. 2, is distributed by a pair of rollers between the drums, the rotatable tube 17 has two rows 19, 20 of holes as shown in development in Fig. 6, and may also have shorter rows parallel to row 19 for supplying ink in a wide band or bands if required; the non-rotatable tube 18 fitting closely within the tube 17 has a single row parallel to the row 19, but the holes of which are spaced axially as those of the row 20; a third tube 22, with widely spaced holes along its length to give a uniform ink distribution, is spaced inwardly within the tube 18 and connects with a supply tube 32. The tube 17 is adjusted rotarily by a handle 12 through gearing 13, 14, 16, the setting being indicated by a drum 29 having lines 30, 31 (corresponding to the rows of holes 19, 20) on its periphery, visible through a narrow slot in a fixed metal cover 25. The drum 29 constitutes an exchangeable ink-container which is clamped, by a spring 39, between a movable pump body 37 and a coupling disc 27 keyed to the shaft of the handle 12; a pin 28 ensures correct location of the lines 30, 31 relative to the rows of holes 19, 20. The shaft of the handle 12, and the tube 17, are keyed to their gears 13, 16 with axial freedom; axial pressure on the handle 12, or automatic movement of an arm 44 as described below, causes the pump body 37 to move over its fixed piston 40 whereby ink in the pump is forced through a valve 35 to the supply tube 32; the latter, being rigid, moves the tubes 17, 18 axially (provision for slight initial lost-motion may be made), this movement being set by an adjustable stop 69 to equal or to exceed slightly the axial spacing of the holes in the row 19; on release the spring 39 restores the parts to the Fig. 2 position, ink being sucked through the valve 34 into the pump; a piston 36 in the drum 29 follows the ink as it is withdrawn. In a modification the tubes 17, 18 have rows of closely spaced holes and are not movable axially; the supply tube 32 in this case is flexible. Automatic pump actuation.-An oscillating lever 54, Fig. 3, coupled to the drive of the duplicating machine is linked at 55 to a lever 56 having a bolt 58 engaging a slot in a lever 57 which carries a pawl 59 engaging a ratchet wheel 50 having a non-return pawl 68; the pawl spring 59a also serves to keep the lever 57 against the bolt 58 except when the lever 57 is arrested by a stop nut 60 adjustable by a knob 64 along a screwed spindle 61, the stop setting, and therefore the revolution time of the ratchet wheel 50, being indicated by a pointer 66 against a scale 67. Instead of the nut 60 being adjustable the transmission ratio in the lever system 54 ... 57 may be variable. The ratchet wheel 50 is secured to a cam disc 49, Fig. 2, engaged by a pin or roller follower 48 projecting from a rod 42 having a projection 46 engaging a projection 47 on the rod 43 of the arm 44; the rod 42 is loaded by a spring 45 and has axial and rotational freedom limited by a roller 51 in a wide slot 52 of a fixed bush 53, the arrangement being such that as the follower 48 rides down from the cam peak the spring 45 pushes the parts 42, 43, 44, 27, 29, 37, 32, 17, 18 to the right; at the base of the cam track the torsion of the released spring 45 is reduced while just beyond this point the friction between the cam and the follower 48 becomes greater, whereby the projection 46 is turned away from the projection 47 (see Fig. 3) and the spring 39 immediately restores the pump body 37 and associated parts to the left, Fig. 2; the follower 48 takes sufficient time to climb up the ascent of the cam 49 for manual inksupplementation to be carried out by means of the handle 12 where required.