Patent GB-499056-A (GB)
Title: A new and improved machine for printing designs on fabrics or papers
IPC: B41F15/42
Filed: 1937-10-09
Abstract: 499,056. Stencilling - apparatus. MASSON, C. Oct. 9, 1937, No. 27513. Convention date, Oct. 9, 1936. [Class 100 (ii)] Relates to apparatus for stencilling patterns on a web of fabric or paper, of the kind comprising a printing-carriage movable along rails on a long table, and comprises an inkscraper which is automatically reciprocated over the stencil by a centrally-disposed guided driving-member and is supported through a longitudinal pivot about which it can rock freely to adjust itself to any unevenness of the table with respect to the rails. Figs. 2A, 2B, and 2C together represent a side view of the machine. The stencil is mounted on an auxiliary carriage consisting of side tubular members 3 connected by cross-tubes 4 and carrying a stencil-frame, the main carriage extending beyond the other at each end and having side tubes 6 slidable within the tubes 3. To facilitate raising the stencil-frame, it is supported at one end on a cross-bar 12, fixed to slides 13 movable in guides 14 traversed by a shaft 15 carrying at each end a pinion 16 engaging a rack 17, a hand-lever 22 being adapted to actuate a lever 18 connected to the shaft 15. Both carriages roll on rails 2 by means of wheels 9, 10 respectively. In the normal position, the stencil-frame is down on the work, the outer carriage is locked to one of the rails 2 by clamps 24 pivoted at 25 and separated at their upper ends by a wedge 26, and the inner carriage is free to be adjusted to an exact position relatively to the work. On operating the lever 22, a slide 31 is lowered whereby the wedge 26 is raised to release the clamping pressure, and a projection 36 on the slide engages a recess 37 in the inner slide to lock the two carriages together for movement to a new position along a work-table 1. A scraper 38 is adapted to rock about a pivot 40, to an extent limited by screws 43, in a carrier 41 pivoted at 44 to a bar 46 slidable vertically in a carriage 47 sliding on guide rods 48, 49 carried by the outer carriage ; the carriage 47 has two sleeves 50 engaging the rod 48, and a tubular extension 53 receiving a rod 52 projecting from a single sleeve 51 on the rod 49. The rods 48, 49 are fixed at the righthand side to a member 71, pivoted at 72 and at the left-hand side to an upright 76 by a screw 75 by loosening which the whole scraper support may be raised to provide access to the stencil. The scraper carriage is reciprocated by an endless chain 77 passing over sprockets 78, 79, the latter being driven from a pulley 85 coupled by a clutch to a driven pulley 86. In the movement to the left of a stud 89 on the chain, the stud engages the upper one of two notched levers 60 on the carriage 47 thereby moving the carriage to the left, and at the end of the stroke, swings the lever down until released therefrom and then engages the lower lever 60 for the return stroke. At each end of its stroke, the scraper is raised and is lowered again behind the ink collected during that stroke. For this purpose, the carriage 47 has two rollers adapted to engage under a ramp 96, and a roller 54 fixed to the bar 46 rides on to the surface 96 of the ramp and falls on to a surface 94 for return to the screen. In a modification, the ramp is in the form of a pivoted lever which tips over when the roller 56 passes the pivot. The clutch through which the chain 77 is driven comprises a pin 101, Fig. 12, engaging a recess 102 in a driven sleeve 100, declutching being effected whenever an arm 105 is moved into the path of an arm 103 carrying the pin. The arm 103 is fixed to a shaft 106 turned by a pawl 118 on a lever 117 lying in the path of a stop 65 projecting from the scraper carriage 47 ; the stop may be fixed in various positions according to the number of reciprocations of the scraper required. The parts are returned to normal working' position by turning a member 127 adapted to disengage the pawl 118 and a second pawl preventing reverse rotation of the shaft 106, but this can only be done when a lever 130 is moved out of the path of a stop 129 by a rod 132 actuated when the lever 22 is operated to lower the stencil frame. Fig. 28 shows a modification of the scraper. A plate 183 fixed to the top of the scraper 38 is clamped between jaws 184 on a support 186 pivoted at 187 to the bar 46 and having a pin-and-slot connection 191 with a lever 189 pivoted at 190 to the same bar. At each end of its stroke, the lever 189 frictionally engages a knife 195 which tends to hold the top end of the lever and consequently reverses the inclination of the scraper and causes it to engage behind the ink accumulated on the stencil and to carry it back over the stencil. In modifications : (1) the stencil frame is supported at one end by a rod adjustable for height and is adjustable transversely ; (2) the carriage 47 slides by means of rollers on two bars of square cross-section and carries two rods terminating in bent stops in place of the levers 60 ; (3) the scraper works in a frame which is shorter than and is movable within the stencil-frame ; (4) the main carriage is locked to both rails.