Patent GB-949325-A (GB)
Title: Improvements in or relating to a method of and apparatus for feeding sheet material
IPC: B65H3/36
Filed: 1960-12-19
Abstract: 949,325. Sheet-feeding apparatus. J. E. THOMPSON. Dec. 18, 1961 [Dec. 19, 1960; May 9, 1961], Nos. 43637/60 and 16882/61. Heading B6B. A sheet-feeding apparatus comprises three spaced lips 6 adapted to overhang the front end, relative to the direction of final feed, of a pile of sheets of material, an oscillatable perforated tube 7 adapted to direct streams of air between the sheets to aid separation thereof, and two movable sucker mechanisms arranged such that, with the apparatus in operation and gas streams issuing from the tube 7, a first sucker mechanism comprising an arcuateshaped pivotally mounted trough 14 carrying a housing 15 which accommodates a sucker 18, engages the rear end of the upper sheet 40 and moves it backwards so as to release the sheet from below the lips, whereupon the second sucker mechanism, comprising L-shaped suckers 21 operable independent of one another, descends to engage the leading edge of the sheet to move it forwardly over the lips 6 to chain conveyer mechanism 28, 29 carrying grippers 30. Air is blown through nozzles constituting the outer lips 6 to prevent the sheets from catching on the lips. Lays 1, 2, posts 4 and brackets 5 carrying the lips 6 form the pile containing frame of the apparatus which has a vertically movable floor 37 which rises at a rate dependent on the sheet-feed rate. The frame is adjustable both longitudinally and laterally to accommodate various sheet sizes and upward movement from the pile of the upper sheet during its transportation is limited by a grid 9 which is adjustable in length. An air tube similar to the tube 7 may be provided at the front end of the apparatus. In operation, air is blown through the oscillating tube 7 whilst the sucker 18 is brought to engage the rear end of the upper sheet 40. The trough 14 is then rotated to the position shown in the drawings, this movement causing the sheet to move backwards and thus be released from beneath the lips 6. The L-shaped suckers then descend to grip the front end of the sheet at the sides thereof, air being blown through pipes 23 to lift the sheet towards the suckers. The suckers then move upwardly and forwardly and in an upward direction whilst moving slightly outwards to tension the sheet. After this travel the grippers 30 engage the sheet, the suckers release the sheet and then turn outwardly and down out of the path of the sheet before moving below the sheet back to the initial position to engage a second sheet to be fed. As soon as the suckers 21 engage the sheet the sucker 18 releases its grip so as not to impede the feed of the sheet to the conveyer mechanism. The trough 14 then rotates back to the position where the sucker 18 engages the second sheet. Kidney-shaped blades 22 are provided in association with the suckers 21 to pass beneath the sheet held by the suckers to separate any other sheets which may have been sucked up in sympathy with the upper sheet. Each sucker 21 is mounted in a control housing 20 and is controlled by a motor 24, geared thereto, so as to be vertically movable in dependence upon the top level of the pile, the adjacent outer lip-carrying bracket 5 being pivotably mounted to operate a lever 33 and thus actuate switches 34 and 35 to successively lower the associated sucker 21 and its control housing 20, mounting arm 31 and bracket 5 and then stop it. Double-feeding at the rear of the apparatus is prevented by a rotating sucker roller 41 which opposes the sucker 18 as the trough rotates to move the upper sheet backwards, and removes any second sheet that may be present. If a second sheet should be caught the roller 41 returns it to the pile. This latter roller will not return the second sheet fully into the apparatus, so that if, for example, a half sheet is accidentally present in the pile it will be gradually fed further and further back by repeated operation of the trough and sucker roller 41. Rapidly rotating rollers (not shown) are located behind the roller 41 for removing such a half sheet when it has been fed back a sufficient distance out of the apparatus. The air issuing from the tube 7 may be cut-off when the upper sheet has been engaged by the sucker 18. In such a proceedure, nozzles (not shown) are then caused to descend at the rear of the apparatus and engage the top of the second sheet and blast high velocity air between this sheet and the upper one caught by the sucker so as to ensure that the two sheets do not adhere by friction. Overhanging lips 6 may be provided at each end of the apparatus and the sucker mechanism at the rear end may be similar to that at the front.