Patent GB-785762-A (GB)
Title: Improvements in or relating to sheet feeding mechanisms
IPC: B65H9/14
Filed: 1954-10-12
Abstract: 785,762. Feeding sheets. BACKHOUSE, H. T. Oct. 12, 1955 [Oct. 12, 1954], No. 29403/54. Class 100(1) Sheet registration. In apparatus wherein sheets are fed by conveyer means on to a feed-board where registration is effected, at least two sheet slowing down means are provided which travel with and retard the speed of the sheets as they approach the front lays, and each means is arranged to operate in turn on successive sheets, one returning to starting position whilst the other is operating on a sheet. The slowdown means may comrise preliminary lays, or suction grippers, or both. Sheets 11, Fig. 1, are fed in overlapping form on to a table 10 by a tape-conveyer where the front edge of each sheet is registered by main lays 12 constructed and operated as described in Specification 657,618. On each side of the table there is arranged a double slow-down device each comprising two preliminary hook-shaped lays 20, 21, each lay secured to the front end of a carriage casting 24. Each casting 24 has a roller 25 at its rear end running in a curved guide slot 26 in a fixed side plate 27. The casting 24 is reciprocated by a lever 30 pivoted to the plate 27 at 28, the lower end having a roller 38 engaging, under spring pressure, a cam 39 secured to a drive shaft 14, and the other end being slotted to receive a slide 33 pivoted on the casting 24. A support 40 for each casting which also imparts vertical movements thereto, is slotted at the lower end to fit over the shaft 14 and has a roller 44 engaging a cam 45; the upper end is pivoted to the casting on a pin 41 which passes through a slot 46 in the plate 27 and has a large head 48 engaging the margin of the slot. In operation, starting from position A with the lay 20 or 21 above the table 10 to intercept the front edge of a sheet advancing over the table, the lay is operated by the cams 39, 45 to move rearwardly and downwardly along the table to position B, the sheet being retained and registered by the main lays 12 prior to the position B. Thereafter the lay drops to postion C below the table and is. returned to position A. The two lays 20. 21 operate 180 degrees out of phase and on alternate sheets, so that when one is at A the other is at the opposite end of the travel. An air-blast from transverse concentric tubes 50, 51, one of which is rotated or oscillated to bring slots in the tubes into register periodically, ensures that the sheets engage behind the hooks of the lays 20, 21. In Fig. 5, there is shown a suction gripper 60 associated with each preliminary slow-down lay. Each gripper is independently mounted on a slide 61 guided on fixed rods 62 and reciprocated by a lever 64 operated by a cam on the shaft 14. Each gripper is attached to the upper end of a hollow piston rod 66 having a piston 67 thereon arranged in a cylinder 68 on the gripper slide 61. The cylinder is double-acting, has both ends open through ports 70, 71 to a common inlet 72, and the lower end communicates with the gripper through a hole in the piston and the hollow rod 66. A light spring 69 normally holds the piston, rod, and gripper in the lowest positions. Suction is established in the inlet 72 through a pipe 77, a port 76 in one end of a bell-crank lever 75, and a fixed port 79, the lever 75 being rocked by a cam on the shaft 14. The arrangement is such that when the inlet 72 is connected to a source of vacuum the gripper 60 rises against the action of the spring 69. When, however, the mouth of the gripper is sealed by a sheet, the gripper is pulled downwardly pneumatically, and is moved downstream to insert the leading edge of the sheet under the lay 20 or 21. Specification 715,895 also is referred to.