Patent GB-741226-A (GB)
Title: A machine for separating and removing sheets from a pile
Inventor: TEBBS GEORGE WILLIAM
IPC: B65H5/02
Filed: 1952-04-15
Abstract: 741,226. Feeding sheets. BACKHOUSE, H. T. April 13, 1953 [April 15, 1952], No. 9463/52. Class 100 (1). A machine for separating and removing sheets from the top of a pile comprises a separator mechanism which descends as the pile is consumed and separates from the pile a part of the top sheet, and a gripper means which moves in an upward path and takes successive sheets from the separator mechanism at varying height positions in the path corresponding to the changing height positions of the separator and to convey the sheets in succession upwardly to a delivery station fixed in position. General arrangement.-Sheets &c. 20 in a pile, resting on a base which is fixed, are separated by friction rollers 127 and by suckers 140, the latter carrying the sheets between the jaws of two grippers 151 which are mounted on endless chains 150, and the grippers carry the sheets upwardly and deliver them to conveyer belts 202 for forwarding in an overlapping stream to a printing &c. machine. The suckers and friction rollers are lowered, as the pile diminishes, under the control of a feeler resting on the top of the pile, and means is provided to preserve synchronism between the suckers and grippers in all vertical positions of the suckers. The apparatus is driven from a primary driving gear 50, Fig. 1, which is geared to sprocket-wheels driving an endless roller chain 57 which is operative to actuate the sheet-separator units, and is geared to a shaft 60 which drives the chains 150 carrying the grippers 151. Sheet-separators.-Two separator units 39, Fig. 1, are adjustably mounted on two tubular cross-bars 37, 38 carried by two end blocks 35, 36 guided for vertical movement in uprights 22-25. The drive-shaft 66 for the units 39 carries a sprocket-wheel 65 against which the chain 57 is held by idler sprockets 67, the arrangement being such that when the separator units are lowered, the sprocket 65 rolls down the chain 57, and the timing of the operations of the separators is advanced so that there is a constant relation with the movements of the grippers 151. In a modification (Fig. 21, not shown), the chain 57 is replaced by a vertical driving-shaft which drives the shaft 66 through bevel gearing, the bevel gear on the driving shaft having a key engaging a helical keyway on the shaft, the pitch of the helix being equal to that of the grippers 151. The rate of descent of the separator units is controlled by a feeler 70  carried on a rock-shaft 71 oscillated by a cam 72 on the shaft 66 whereby the feeler is raised during separation of each sheet and then lowered on to the pile. When the pile is diminished by a predetermined amount, an arm on the shaft 71 cannot obstruct the movement of a cam-actuated link which then co-operates with pawl-and-ratchet means to operate through worm-wheel gearing to rotate a transverse shaft 95, Figs. 1 and 10. Pinions 96, 97 at the ends of the shaft 95 engage rack teeth 99 on the uprights 23, 25, so that the whole of the separator mechanism, and two cam units 40, 41 carried thereby, is lowered. The height of the separator mechanism can be adjusted manually on rotation of a hand wheel 103 which can be clutched to bevel gearing to rotate a vertical shaft 87 associated with the vertical movements of the separator mechanism. The drive shaft 66 can be driven intermittently by an arrangement comprising an endless chain, such as 57, which is guided around a wheel such that rollers spaced along the chain can engage in radial grooves in a pair of discs and rotate them intermittently. This rotation is imparted, through gears to the shaft 66. There are two separator units 39 (only one is shown in Fig. 1) each arranged on the outside of one of the gripper units 45, 46 and comprising a box-like casting 110, Fig. 6, adjustably clamped to the tubular members 37, 38. A stub shaft 113 in the casting is rotated from the drive shaft 66 through bevel gearing to drive, through spur and chain-and-sprocket gearing, a comber wheel 127, Fig. 7, which operates, in conjunction with that in the second unit 39, to push the corners of the top sheets of the pile inwardly towards one another to form humps which are subsequently engaged by the suckers 140; two presser members 142, 143, Fig. 1, are lowered on to the pile to assist the formation of these humps. The comber wheel 127 is mounted on a bell-crank arm 125 which is swung about a pivot shaft 126 by a cam 118, excessive pressure on the sheet pile being counter-balanced by spring means. The sucker 140 in each unit is carried at the free end of a rod 134, Figs. 6 and 7, slidable in an arm 133 but held against rotation therein by means of a square block 135 which carries a roller 137 co-operating with an adjustable cam 138. The arm 133 is secured to the shaft 126 which is rocked by a cam 119. When the two suckers 140 rise with a sheet, they move outwardly by the action of the cams 138 to tauten the sheet, and then present the sheet to mechanical grippers 151. A finger 195 limits the downward movement of each sucker. Air blasts and flips ensure that only one sheet is separated at a time. Sheet-carriers; grippers.-The two chain gripper units 45, 46 each comprise an endless roller chain 150, Figs. 1 and 10, having a number of grippers 151 thereon each including a plate 153, Fig. 13, and two jaws 156, 158. The jaw 156 is pivoted at 154 to the plate, the jaw 158 is pivoted at 157 to the jaw 156, and a spring 159 urges them together. The jaws 156, 158 carry rollers 160, 161, respectively, and a steady roller 163 is mounted at 154 on the plate. The jaw 156 is held in two extreme positions of rotation about the pivot 154 by a toggle spring 165, these positions being limited by a stop 168. The chain 150 moves between guides 170, Fig. 1, and is driven by a sprocket 171, splined to the shaft 60, at the same speed as the chain 57 for the separator units. The chain gripper units 45, 46 are supported on cross-bars 29, 31, and are adjustable towards each other by a hand wheel 49 operable on pinions 47, 48 engaging rack teeth on the cross-bars; the cam units 40, 41 also partake in this adjustment. In the guideway for each chain 150 there is a cam 172 for opening the grippers to release a sheet to the conveyer belts 202, and a cam 173 which turns over the grippers from an inoperative trailing attitude to an operative position; a further cam 174 and a support surface 175 embodied in each of the adjustable cam units 40, 41 effect opening and closing of the gripper jaws in sheet-receiving position. The gripper, after taking a sheet from the suckers 140, gradually turns downwardly to conform with the attitude of the sheet due to the inclination of a guide-bar 190 pivoted at 191 and positioned by the cam unit 40 (or 41). Arcuate guides 200, 201, and pressure rollers 203, 204, Fig. 1, support the sheets carried by the grippers to the conveyer belts 202.