Patent GB-299410-A (GB)
Title: Improvements in platen printing presses
IPC: B41F1/28
Filed: 1927-07-26
Abstract: 299,410. Marks, E. C. R., (Eisenwerk und Maschinenbau Akt.-Ges.). July 26, 1927. Grippers and gripper mechanism; sheet feedtables; sheet-registering devices.-In a platen printing-press, the grippers are arranged to travel round the platen and to move alternately a short distance in one direction and then a longer distance in the opposite direction, in order to take a sheet from the feed-table, lay it on the platen, and then remove it and deposit it on the delivery board. The feed-table is arranged to oscillate up and down to permit the grippers to pass under it when moving in one direction, and to bring its edge into position for the grippers to seize the sheet-when moving in the opposite direction. The platen 2, Fig. 2, reciprocates towards and from the forme 4, and carries at each side an endless chain 17 provided with two sets of grippers 18, 19. The fixed jaw of the grippers is secured to a shaft 24, Fig. 5, journaled in bearings on the chains and held by a pawl 27 against the action of a spring in the position shown. The movable jaw is mounted on a shaft 20 carried by arms 25 secured to the shaft 24, and is normally kept closed by a spring, a pawl 22 on the shaft 20 being actuated by correctly-positioned cams for opening the grippers. On the shaft of one pair of wheels carrying the chains 17, a gear-wheel 29, movable in a frame 30, Figs. 2 and 3, is slidably arranged. The frame 30 is provided with an upper and a lower rack, which each occupy, in the centre of the frame, one half of the width of the frame, but at the ends, are widened so that, where one rack occupies the whole width of the frame, the other is absent. Cams 33, 34 act to move the wheel 29 from one side to the other of the frame. When the platen commences to move from the printing-position shown in Fig. 2, the wheel 29 is rotated by the lower rack 32 and moves the chain in the direction x so that the grippers 18, which have been positioned during printing below the platen, move upwards to seize the printed sheet. The pawl 27 is engaged by a cam 38 to permit the grippers to swing the sheet clear of the stops 41 on the platen. At this point, the gear-wheel has reached the position a and so passes into engagement with the upper rack 31, this resulting in a reversal of its rotation and the movement of the chain in the direction y. This movement continues until the limit of movement of the platen is reached, when the grippers 18 are opened to deposit the sheet on the board 43; at the same time, the grippers 19 have moved forward until they occupy a position at the upper front edge of the platen, and the wheel 29 has been pushed by the cam 33 to the other side of the frame. When the platen commences to return, the movement of the chains 17 is again changed to the direction x so as to move the grippers 19 up to the edge of the feed table where they are opened and allowed to grip the sheet lying thereon. When the wheel 29 reaches the point b it passes out of engagement with the rack 31 and into engagement with the rack 32 and again reverses its rotation. This results in the grippers 19 carrying the sheet over the platen and being opened to deposit it against the stops 41, finally passing on to the position occupied in Fig. 2 by the grippers 18. The feedtable 45 is pivoted at 49, Fig. 12, to a horizontal table, and both are carried on a movable frame adapted to be screwed to the main frame of the machine. The table may be provided with an endless conveyor 62. The table is normaliy held raised by a bell-crank lever 54 actuated by a cam 60 so constructed that the table is held raised to permit the grippers to pass beneath it, but lowered at the time when the grippers are moving forward to seize a sheet to be carried to printing position. Arranged in front of the table is a fixed bar 65, Fig. 14, formed with slots in which are mounted slidable hooked stops 46. A bar 67 is screwed to the stops 46 and carries end stops 68 that normally rest on the table 45. The stops fall with the table until the hooked ends of the stops 46 engage the bar 65, after which the table falls alone to allow the sheet supported thereon to be removed by the grippers.