Patent GB-753426-A (GB)
Title: Sheet feeding apparatus
IPC: B65H3/08
Filed: 1954-09-13
Abstract: 753,426. Feeding sheets. DEXTER FOLDER CO. Sept. 13, 1954 [Dec. 11, 1953], No. 26417/54. Class 100 (1). Sheet feeding apparatus comprises a pair of transversely spaced vacuum sheet separators reciprocated pneumatically towards and away from a supply of sheets to grip and lift the top sheet, means supporting the separators for pivotal movement about fixed axes parallel to the feed direction, cam-actuated means for swinging the separators away from each other with a positive movement to stretch the sheet, and resilient means for swinging the separators towards each other after the sheet is stretched and released. Pile tables.-A pile 20, Fig. 1, of paper, cardboard or like sheets is supported against a plate 21 on a pile board 19 supported on side bars 17, which are moved upwardly to feed position and thence intermittently to maintain the height of the pile by cables 12, 13 from a driven shaft 15. Sheet separators.- Two sheet separating mechanisms 22, Fig. 2, and 23, Figs. 1 and 2, are provided, to engage and lift the top sheet near its rear corners and deliver it to sheet forwarders 89. The separating mechanisms comprise brackets 24 mounted on shafts 25, 26. A rotary valve mechanism 45 is driven from a cam-shaft 46, and flexible conduits 44, 70 connect the pressure and suction sides respectively to the separating mechanisms 22, 23. The separating mechanisms are identical,. although inverted with respect to each other, and only the mechanism 23 is described in detail. The mechanism 23 is adjustable along the shaft 26 by a screw 27, Figs. 1, 2 and 3, according to the sheet width. The bracket 24 has a groove 29 accommodating a square bar 30 secured by a cover-plate 32 and having its downward movement adjusted by a nut 31, but being free to move upwards. The bar 30 supports a further square bar 34 which carries a blow-pipe 35 connected to a conduit 44 and having a thin air jet slot. The bar 34 slidably supports a further square bar 40 which carries a second blow-pipe 41 with a slot 42. The pipes 35, 41 are arranged adjacent the rear face and a side face respectively of the pile, near a rear corner thereof, and are aligned with the top part of the pile. Air is blown from the pipes 35, 41 prior to engagement of the sheets by the suction separator 47, so as to effect a preliminary slight separation of the upper sheets in the pile. The separator 47 is pivoted on an axis extending in the direction of sheet feed but inclined slightly downwards forwardly, by means of a bearing 52 and journal 51, and is biased by a tension-spring 86 so that its further side rests against a contact member 84. The separator 47, Figs. 3 and 6, comprises a cylinder 48, upper and lower caps 49, 55, and a piston stem 57 carrying a piston head 58 and slidable in the cap 55, the stem 57 carrying a rubber suction cup 64. The space outside the stem 57 is connected to the suction side of the valve mechanism 45 by a conduit 70, and communicates with the interior of the stem through ports 63. The interior of the stem communicates also with passages 62 leading through the head 58. In operation, when the conduit 70 is connected to vacuum, the interior of the stem 57, being open to atmosphere, is not under vacuum, and neither, therefore, is the space above the head, which is therefore lowered against the action of a spring 67, so as to lower the stem 57 and cup 64, until the latter engages the top of the pile 20. Vacuum is thereupon produced in the stem and above the head, which is moved upwards by the spring 67, so that the rear edge of the sheet is raised, and also moved forwards owing to the inclination of the cylinder 48. The sheet is delivered to the forwarders 89 and the suction cut off to release it. The operation described is suitable for use with relatively thick cardboard sheets. For use with thin paper sheets, however, whose rear edges are already substantially raised by the air from the pipes 35, 41, it is required that the cup 64 shall engage the top sheet, but shall not press it down against the pile. The downward movement of the cup is therefore adjustably limited by rotating a nut 103 so as to raise a stop 97 to a position where it will check the downward movement of the stem 57 by engaging a shoulder 61 thereon. The stop 97 has grooves 98 to allow passage of air. A cam 71 on the shaft 46 engages a roller 72 on arm 73 of a bell-crank 74 whose other arm 76 is connected to an adjustable link 78 connected at 79 to an arm of a further bell-crank pivoted at 82, whose other arm carries adjustably the contact member 84. After a sheet has been raised, the cam acts to swing the separator 47 against the action of the spring 86, so that the cup 64 moves away from the equivalent mechanism 22, Fig. 2, so as to stretch the sheet and ensure that the whole rear edge thereof is raised. The normal inward position of the separator 47 is adjustable, so as to be vertical or inclined, by altering the length of the link 78 or adjusting the contact member 84. The amount of outward movement for stretching the sheet can be adjusted, or such movement can be prevented entirely, by rotating a nut 112 so as to adjust a bell-crank 106, an arm 108 of which carries a lug 109 which engages the bell-crank arm 76, whereby the return movement of the bell-crank 74 is controlled. Thus the initial inclination and the amount of stretching movement of the separators 47 in the mechanisms 22, 23 can be adjusted separately, according to what is found to be most satisfactory for the particular sheets being used. Sheet forwarders.-The sheets are delivered by the separators 47 to the forwarders 89, which are mounted on a shaft 92, Figs. 1 and 2, rocked from the shaft 46 so as to oscillate the forwarders 89 between a rearward sheet-receiving position shown in chain lines in Fig. 2 and a forward and raised position where the sheets are delivered to a feed roller 94 and conveyer tapes 96, which advance the sheets to a printing- press or other machine, either singly or in lapped relationship according to the speed of the tapes. The forwarders 89 are connected by conduits 93 with the vacuum side of the valve mechanism 45, and the vacuum connection is made and broken at the requisite times. Specification 438,480 is referred to.