GB715895A - Improvements in or relating to sheet feeding mechanisms - Google Patents

Abstract

715,895. Feeding sheets. BACKHOUSE, H. T. Aug. 15, 1952 [Aug. 22, 1951], No. 19824/51. Class 100 (1) Sheet-registering devices.-In apparatus for feeding sheets over a feed board for front and side registration, a suction gripper 30 is raised by suction or other means until it engages a sheet 26 on or just above the feed board 10 whereupon the sheet seals the mouth of the sucker and causes suction means to withdraw immediately the sucker gripping the sheet to a position level with or just below the level of the feed board. The sheets are fed by conveyer means over the feed board 10 in overlapping formation, and this may continue even when the front of the sheet is gripped, so that a slight buckle is formed which is employed to urge the sheet forward to the front stops 37 when the sheet is released. Alternatively, the grip on the sheet by the sucker 30 may be light enough to allow forward movement of the sheet. Each suction gripper 30 comprises a hollow piston rod 30 attached to a piston 29 which is urged downwardly by a light spring 32 and slidable in a cylinder 28 formed in an arm 18 fixed on a rockable shaft 11 supported in fixed brackets 13 beneath the feed board 10. Each suction gripper is spring-pressed against a bracket 13. A source of suction is connected by a pipe 15 to a port 16 within each bracket 13, and, in the upright position, a port 36 (not shown) in the arm 18 registers with the port 16 to allow both ends of the cylinder 28 to be connected to the suction source. An adjustable air-inlet valve 40 in the arm 18 enables the suctional force on the piston, and the grip on the sheet by the gripper 30, to be regulated, and allows release of the sheet when the suction has been cut off from the cylinder. The arm 18 extends upwardly through a slot 22 in the board 10, and has a preliminary stop 25 thereon. When the shaft 11 is rocked, the arms 18 are rocked towards the front stops 37 until the preliminary stops 25 are lowered beneath the board 10. In the upright position, Fig. 5, the ports 16 register, suction is applied to both sides of the piston, the lower side is open to atmosphere through the hollow gripper 30, and therefore the gripper rises to engage a sheet 26. When this occurs, the gripper mouth is sealed, suction builds up be'ow the piston (which here has a larger effective area due to the absence of a rod), and the piston and gripper are caused rapidly to lower, carrying the sheet with them, so that the front edge of the sheet is below the preliminary stop 25. The arm 18 then rocks to move the gripper 30 and sheet 26 towards the front stops 37, the ports 16, then move out of register so that suction to the gripper is cut off, and the sheet is released. Sheet-smoothers.-To ensure that the sheet shall not ride over the front stops 37 after it has been released by the suction grippers 30, bars 41 are lowered to press the sheet downwardly after the rear portion of the preceding sheet has moved beyond the stops 37. Specification 446,886 is referred to.