Patent GB-774874-A (GB)
Title: Improvements in or relating to sheet separating machines
IPC: B65H5/02
Filed: 1953-06-01
Abstract: 774,874. Feeding sheets. BACKHOUSE, H. T. Sept. 1, 1954 [June 1, 1953; March 24, 1954], Nos. 15274/53, and 8637/54. Class 100(1) Sheet-separators. In apparatus for separating sheets from a pile and removing them therefrom to produce a succession of partly overlapping sheets, although a sheet is lifted in each complete cycle, it is not reforwarded until the next cycle of the sheet-lifting operation commences. The beginning of the cycle is defined as the time of application of an air-blast against the side of the pile to blow up the sheets. Sheets may be separated either at the front or rear of the pile. As shown, the sheets are lifted at the rear of a pile 30 by corner suckers 94 which lift them up to stationary suckers 130, then suckers 142 take them forward over the pile to a position where they can be grasped by a sucker 150 which feeds them between a feed roll 152 and presser rolls 154, and these forward them to a conveyer 156. Adjacent each corner of the pile a main bracket 32, Fig. 9, is supported on two holhollow cross bars 33, 34, and supports a cam shaft 36. An air blast nozzle 40, adjustably arranged on a small bracket 38, is arranged to blow air diagonally across the side of the pile 30 to fluff up the corners of the top sheets. The bracket 38 guides a rod 44 for a presser foot 46 which is lifted vertically by a cam and bell-crank means, and returned downwardly by a spring. A roller 56. secured to the rod 44. runs in a cam slot 58 in the guide bracket 38 so that the foot 46 turns inwardly to press on the top of the pile 30, beneath the top sheet. The air supply to the blower 40 can only be established when a groove 66 in the rod 44 registers with ports in pipe connections 64, 65 arranged at each side of the rod. The corner sucker 94 is arranged on a guide bar 70 which forms one arm of a bell-crank lever pivoted on a stub shaft 68, the other arm 72 having a roller engaging a cam 74 under the action of a spring 75, whereby the bar 70 moves towards and away from the rear edge of the pile. A slide 76, carrying the sucker 94, is guided on the bar 70, and is coupled by a link 78 to a further bell-crank lever 80 having a roller co-operating with a cam under the action of a spring. A hollow shaft 86, Figs. 11 and 12, in bearings on the slide 76 carries two arms 88, 90. The sucker 94 is carried by an arm 92 pivoted to the free end of the arm 88, and a. spring 96 acts through a pivoted plate 98 to urge a pin 100 on the arm 92 up to a stop 102 on the arm 88, and so tends to rotate the arm 92 outwardly towards the side of the pile. The loading of the spring 96 can be adjusted by a screw 104. The downward movement of the sucker 94 is limited by a stop screw 106 on the arm 90. Suction is applied to the sucker 94 from a pipe 108, hollow shaft 86, and passageways in the arms 88, 92. A further suction connection from the shaft 86 leads to a cylinder 112, formed in the slide 76, having a spring-loaded piston 113 carrying a pin 114 with a forked end engaging a projection 116 on the arm 88. When suction is applied to the sucker 94, and a sheet is fluffed up by the blower 40 to seal the mouth of the sucker, suction builds up in the cylinder 112, pulls upwardly the piston 113, and so causes the arm 88 and sucker 94 to pivot upwardly about the shaft 86, and to bend the edge of the sheet about a bead or stop 120. Thus the two corner suckers 94 tauten the edge of the sheet transversely. The stop 120 is on a crank 118 carried by the slide 76, and is adapted to seat on the pile 30 in either of two positions, 180 degrees apart, according to the setting of the crank; a variation of this arrangement enables the stop 120 to be positioned in intermediate positions so that the angle through which sheets are bent can be varied to suit sheets of different materials. The stationary suckers 130 are each supported for vertical adjustment on a cross bar on the bracket 32. A housing on the bracket 32 has two rotary valves therein for controlling the suction to the grippers 94, 130. Each forwarding gripper 142 is carried on a swinging arm supported on a rock shaft actuated by a cam. The gripper 150 which engages the underside of the front edge of the sheet, and the feed arrangement 152, 154, and 156 are described in Specification 774,875. At the centre of the pile there is at least one single combined presser foot and air blast nozzle 144 supported for up and down as well as in and out movements as described in Specification 427,041. This foot moves to seat on the pile when the rear edge of the top sheet has been raised. and blows air beneath the top sheet. A fixed air blast nozzle may also be arranged above the centre of the pile and associated with the nozzle 144 through a change-over valve. In operation, starting from the position shown in Fig. 1, the rods 44 of the feet 46 are rising and have established the air blast to the nozzles 40 to blow the top sheet into contact with the suckers 94 to which suction is applied. The sealing of the suckers 94 by tne sheet causes the arms 92 to rotate to lift the suckers so that the sheet is bent at the ends around the stops 120. The feet 46 descent, cutting off the air blast, and move inwardly on to the pile beneath the lifted sheet. The suckers 94 and stops 120 are then raised by the slide 76 to lift up the edge of the sheet into contact with the fixed suckers 130, and the suckers 94 are moved rearwardly clear of the sheet, downwardly, in under the sheet, and then downwardly until the stops 120 seat on the pile. The path of the suckers is indicated by arrows in Fig. 9. During the downward movement of the suckers 94, the feet 46 move upwardly and outwardly and re-establish the air blast to the nozzles 40 when the stops 120 engage the pile so that separation of the next sheet begins. At this time, or shortly after, the forwarding suckers 142 take the sheet from the fixed suckers 130, and move the sheet forwardly. If 360 degrees represents a complete sheet-separating cycle, commencing with the blasts from nozzles 40, the forwarding by the suckers 142 commences between 360 and 400 degrees and is completed at about 590 degrees. and the air blast from the centre nozzle 144 begins at about 160 degrees and finishes at about 460 degrees. In one modification, each corner lifting sucker 94 is adapted to slide upwardly along a fixed inclined hollow rod, and suction is employed to effect the backward and forward movements. The sucker 94 is carried on an arm 200, Fig. 16, radiating from a piston rod 202 having a piston 204 operating in a cylinder 206, against a spring 208, when suction is applied by way of the hollow inclined rod to move the sucker 94 into position over the pile. The movement of the arm 200 is controlled by a roller 210 attached to the piston and engaging a guideway 212 in the cylinder. The end 216 of the piston rod serves as the stop about which the corner of the sheet is bent. The angular movements of the arm 200 to effect the initial lift of the corner of the sheet by the sucker are effected by a separate suction-operated piston 218, Fig. 19, in a cylinder 220, which operate to rotate the cylinder 206 about its axis by means of a radial projection 224 on the cylinder 206 which engages a groove 222 in the piston 218. In a second modification, the backward and forward movements of the corner suckers 94, Fig. 20, are effected by rotation about a nearly vertical rod 250. A stub shaft 252 secured to, the rod carries a stop 254, which engages the pile, and the sucker is carried by an arm 256 pivoted on the shaft 252. The sucker is lifted to bend the corner of a sheet about the stop 254 by rotating the arm 256 through a suctionoperated piston. The up and down movements of the sucker are effected by a camoperated bell-crank lever 258 and a link 260 connected through universal joints to the lever and a bracket 262 secured to the rod 250 which is thereby reciprocated. The movements of the sucker towards and away from the rear edge of the pile 30 are effected by a link 266 connected by universal joints to the bracket 262 and a cam-rocked lever 268 whereby the rod 250 is rocked against the action of a spring. The rod 250 slides in guides in the bracket 32, and a roller on the rod runs along a bar 276,. the inclination of which can be adjusted to rotate the rod 250 whereby the sucker 94, when lifted by the lever 258, can be moved transversely to the pile to tauten the sheet. In all the above arrangements the initial lift by the upward movement of the sucker 94, when its mouth is sealed, bends the sheet about a stop, such as 120 or 216' which rests on the pile and tautens the rear edge of the sheet. The stop may be mounted for rotation, and in the first described construction the sucker is adjustable relatively to the stop. In the form shown in Fig. 20, there may be a short suction tube extending radially from the stub shaft 252 and a sleeve which carries the gripper sucker 94 is slidable along the tube and is urged outwardly from the shaft by a coil spring to stretch the sheet. The corner lifting suckers 94 may move outwardly, downwardly, and inwardly around the side edges of the lifted sheet. Specifications 741,226 [Group XIX], 774,876, 774,877, 774,878 and 774,880 also are referred to.