GB765980A - Improved mechanism for removing sheets singly from a stack of sheets - Google Patents

Abstract

765,980. Feeding sheets. HALAHAN, J., LYON, F. A., and ARONSON, T. F. Nov. 25, 1954, No. 34237/54. Class 100(1) Sheets are partially removed from a stack by a hollow cylindrical suction member which may be fixed or adapted to oscillate about its longitudinal axis, the stack being supported to rest upon the member with an intermediate portion of the nearest sheet adjacent and tangent to a peripheral suction slot in the member. this sheet being sucked down by the member to cover the slot therein, and sheet feeding means then further partially removes the sheet from the stock to a position where sheet removing means grip the sheet and slide it over the suction member, the 'next sheet meanwhile being sucked down to cover progressively the exposed portion of the slot. As shown in Fig. 6, a stack 5 of sheets rests partly on a hollow cylinder 1 having a number of axiallyspaced slots 7 therein extending over approximately 90 degrees of the circumference. Three spaced cylindrical sleeves which are also similarly slotted surround the cylinder 1 and can be adjusted to cover partially the slots 7. The interior of the cylinder 1 is connected to a source of vacuum, and the cylinder adapted to be oscillated about its longitudinal axis through an arc of about 60 degrees. Constantly driven feed belts 31 which pass around the cylinder 1, being situated between the spaced sleeves so that they do not contact the pile 5, co-operate with other feed belts 33 passing around pulleys 30 to remove the separated sheets. A constantly-driven feed roll 45 forces the sheet against the belts 31, and this roll may be retracted once each cycle, when the leading end of the sheet passes it, by means of a rotating cam which contacts a bell-crank lever 40 carrying the roll. The lever 40 also acts as a sheet guide. In operation, as the slots 7 are uncovered by the preceding sheet O the next sheet P is sucked downwardly from the pile 5 to wrap around the cylinder 1, the cylinder is rocked counterclockwise through 60 degrees, the front end of the sheet P is caught by the roll 45 and belts 31 for removal, and the cylinder is then rocked clockwise to suck down another sheet. To rock the cylinder 1, the latter has a shaft provided with a crank which is rocked by a cam on the shaft of the pulleys 30. A sheet counter is operated from the pulley shaft. In a modification (Figs. 8 and 9, not shown) a central slotted portion only of the cylinder 1 is oscillated, the upper feed belts 31 are eliminated, and a valve arranged between the cylinder and the vacuum source controls the application of suction by the cylinder. In the form shown in Fig. 11, the stack 109 of sheets rests on a hollow suction cylinder 104 which does not oscillate. A constantly-driven shaft 106. on which the fixed cylinder 104 is mounted has a rubber faced roller 112 (not shown) secured thereon adjacent each end of the cylinder 104. The rollers 112 are of slightly smaller diameter than the cylinder 104 so that they do not engage the stack, and cooperate with smaller rollers 114 carried by spring-urged bell-crank levers 116 loosely mounted on a shaft 120. The rollers 112 also co-operate with rollers 125 which are retracted once each cycle. The rollers 125 are carried by arms 127 secured to the cross shaft 120, and a lever 128 secured to the shaft is rocked by a cam 130 on a shaft 133 driven by a motor 137. For accurate timing, the shafts 133 and 106 are connected by chain and sprocket gearing. In operation, the bottom sheet of the stack is sucked down on to the fixed cylinder 104 to cover the slots 107 therein, and the rollers 125 move inwardly to press the front edge of the sheet against the driven rollers 112 whereby the sheet is pulled from the stack around the cylinder 104, between the rollers 112, 114, and the sheet falls down a shoot 143. The base of the stack 109 may be struck by a member connected to the rocking shaft 120 to loosen the stack. In a modification of Fig. 11, a rotary valve secured to the rotating shaft 106 controls the application of suction by the slots 107 in the cylinder 104. Another modification of Fig. 11 includes a cam-oscillated finger (Fig. 14, not shown) which rises towards the base of the stack of sheets, just as the bottom sheet is being sucked down, to prevent the other sheets from drooping.