Patent GB-634206-A (GB)
Title: Stencil printing machine
IPC: B41F15/08
Filed: 1947-05-19
Abstract: 634,206. Stencilling-apparatus; feeding sheets. PEMBROKE, G. H. May 19, 1947, No. 13456. [Classes 100 (i) and 100 (ii)] A stencil silk screen apparatus is constructed with (1) improved means for operating the stencil frame 130; (2) with improved sheet-feeding means ; (3) with improved means for actuating the inking carriage 500 and for automatically adjusting the position of the ink scraper so as to enable the printing to be effected as the carriage 500 moves alternately in different directions across the screen. (1) The frame 130 is moved from the position shown in Fig. 1 to that shown in Fig. 2 by means of oscillating sprockets 136, 137 at the front end of the machine and oscillating sprockets 138, 139 at the rear end, the sprockets being provided with crank-pins which operate links which operate push-bars 152, 162 to raise the frame 130, a greater lift being given to the front end of the frame. The movement is controlled by counterweighted chains 172, 173 passing over fixed pulleys 174. The sprockets 136, 137, 138, 139 are operated by a pair of chains 135, each connected to a bar 132 which is oscillated by an oscillating lever 114 or 115, the levers 114, 115 being oscillated by cranks 110, Fig. 1, or 111, Fig. 2, driven by a belt 82 and spur gears from a motor 81. (2) The sheets are fed by hand from a pile 42 which is supported by a board 40 mounted at each side on a parallel linkage 50 controlled by a nut 60 and screw 70. The screw 70 is operable by a handle 71 which may operate by chain gearing to adjust both screws simultaneously. The sheets are placed upon a slat 45 and under a roller 46 carried by oscillating arms 220, and are fed to printing position by inclined belts 180, Fig. 3, which move in grooves 181 in the printing table 20 and 'act upon the undersides of the sheets to effect the feed. The grooves permit the belts to rest in the grooves out of contact with the sheets, but the belts are raised when required to feed. The sheets are registered against side guides 350, Fig. 3, while these are in the raised position. As the stencil frame drops the guides 350 are lowered to clamp the registered sheet. The guides 350 may be grooved to permit the action of movable stops 450, Fig. 29 (not shown), which ensure accurate side register. The stops 450 are arranged to be moved through grooves in the stops 350 to allow of adjustment of side register. The sheets are registered longitudinally by a rising and falling front stop 356, Fig. 3, and the actuation of the registering devices is controlled by the rising and falling motion of the frame 130. The belts 180 at the delivery end of the machine pass over a grooved roller 260, Fig. 3, which is carried by a spring- pressed bar adapted to be depressed by the frame 130 when in closed position, but to be raised as the frame 130 rises. This roller causes the belts to be raised to deliver the printed sheets over the stop 356, and also causes the belts to feed in a new sheet which has been advanced into contact with the feed end of the belts by the action of the friction feed roller 46 and slat 45 when the arms 220 are moved towards the belts by eccentric-andlink mechanism driven by the sprockets which actuate the rising and falling movement of the frame 130. The belts 180 are driven by mechanism comprising a clutch which is thrown in as the roller 16 feeds the sheets to the tapes, and is thrown out as the roller is moved towards the pile by the arms 229. The bars, which carry the side stops, the roller 260, and the stop 356, are held in depressed position by latch devices such as 400, 401, Figs. 1 and 2, which hold the front stop 356 down. These latches are released by the' projection 134 on the reciprocating rod 132, and the latches are arranged so that the stops 350 are released before the stop 356 to permit the printed sheet to pass readily over the stop 356 which is grooved to permit passage of the belts 180 thereover. (3) The inking-carriage 500 moves along the table 20 in one direction during the down cycle of the frame 130 and remains at rest during the up cycle, and then moves back in the opposite direction during the next down cycle of the frame 130. The carriage is fitted at each end with rollers 508, 509, Fig. 8, which move on rails 505, 506 on the frame 130. The carriage is fitted with a squeegee 530, Fig. 19, which occupies the position shown in full or dotted lines according to the direction of movement of the carriage, the position being altered by means of a tilting bar 600, Fig. 2, which engages a pin 602 on a rod 603, Fig. 8 on one ascent of the frame, and at the other end of the traverse of the carriage 500 engages a pin 611 on a bar 612, Fig. 2. The shaft of the squeegee is adjustable vertically by screws 570, and the frame in which it is mounted is held in adjusted position by screws and nuts 586. The carriage 500 is traversed by means of chains 650, Fig. 3, passing over wheels 652, 655, and adapted to be driven alternately in opposite directions to reverse the movements of the carriage. The wheels 652, 655 are driven by a gear 685, Fig. 16, mounted in the frame 130 which engages a gear 682 operated by a gear 680 on a shaft 674 driven by a belt 672 and gearing from the motor 81. The shaft 686 of the gear 685 is moved axially by a projection 750 on the carriage 500 at the end of its reciprocation in one direction, and in the reverse direction by another projection at the other end. Clutches are thus operated to change the direction of drive of the chains 650. The drive to the chains is cut off as the frame rises and takes the gear 685 out of gear with the gear 682, and to prevent movement of the carriage in the reverse direction too soon the gear 680 is moved axially out of driving-connection with the gear 682, and a spring latch means may hold the shaft 686 in position. The belt 672 when moved out of position by axial movement of gear 680 tends to return this gear to normal position. The carriage 500 can be bolted in any position by operation of a pedal 910 connected to a lever 900 which by means of a fork 902 can engage a collar 674a, Fig. 1, on shaft 674 of gear 680 and move gear 680 out of connection with gear 682.