Patent GB-766316-A (GB)
Title: Improvements in sheet separating devices
Inventor: TEBBS GEORGE WILLIAM
IPC: B65H3/54
Filed: 1953-10-08
Abstract: 766,316. Feeding sheets. BACKHOUSE, H. T. Oct. 6, 1954 [Oct. 8, 1953], No. 27733/53, Class 100(1) A sheet-separating device comprises a combined nozzle and pressure foot which is raised from and lowered on to the top of the pile of sheets in timed relation to the action of a suction separator, the nozzle or foot being raised or lowered by means of a piston and cylinder operated by air pressure. In the form described, it is raised by the piston and lowered by spring action, but the piston may alternatively control both movements. The separating apparatus comprises a stop 39, Fig. 3, arranged to bear on the top of the pile 10 adjacent one edge thereof and a suction gripper 43 of the collapsing type arranged to engage and to grip the uppermost sheet between the stop and the adjacent edge and to collapse upwardly carrying the gripped portion of the sheet. bending the sheet about the stop. The stop and gripper are then lifted and moved, still holding the sheet, over the top of the pile to feed the other end of the sheet to forwarding rollers and then, after release of the sheet, are returned to engage the next sheet of the pile. The grippers are carried on a bracket 30 mounted on a cross bar 18 which is supported on brackets 17, Fig. 1, slidable along parallel guides 14, 15 on each side of the pile. The mechanism is controlled by an oscillating shaft 22 driven through an arm 23 at one end which is connected by a slider 24 to a rail 26. This rail is supported at each end on interconnected bell-crank levers so that by rotation of the levers (as described in Specification 763,833) the rail 26 rises and falls but remains horizontal. This provides the rocking movement of shaft 22. The shaft 22 carries for each gripper unit, a twoarmed lever 34 keyed to the shaft and a freely mounted lever 35, carrying an arched arm 38. The cylinder 40 of the collapsible gripper is mounted on this arm so that the hollow piston rod 42 carrying the sucker head extends rearwardly and downwardly. The cylinder and thereby the gripper is supplied with suction through the hollow shaft 22 and a flexible connecting pipe. The collapsing sucker may be of the kind in which suction is applied to both sides of a piston which is urged to the uppermost position by a weak spring. While the sucker is open, and when suction is applied, the piston rod will therefore be projected against the action of the spring by the suction of the lower side of the piston. As soon as the sucker is closed by contact with a sheet it is lifted due to the suction being re-established on the upper side of the piston and exerting a greater pull, due to the greater area, than that on the lower side. Thus the sucker rises assisted by the spring and carries the sheet with it, the edge of the sheet being bent about the stop 39. A roller 46 carried on the arm 38 is adapted to bear on a horizontal rail 31 when the arm 38 is allowed to rise under spring action. This maintains the gripper at a substantially constant height during the forwarding movement to insert the edge of the sheet between forwarding rolls 11, 12. Air blast nozzles 51 with oblique slits are positioned adjacent the top edge of the pile and adapted to blow air against the top sheets so that they are fluffed up. A forked member 56 carries a pair of members 57 constituting the combined presser feet and air nozzles. These are adapted to descend after the top sheet has been lifted and blow air under it. The member 56 is rockingly supported on the air supply tube 50 and is raised by piston and cylinder 58 acting through a link 59. The air pressure to nozzle 51 and cylinder 58 is controlled by the same valve and is transmitted through one side of pipe 50 and by way of connection 64. The air pressure to members 57 is separately controlled and transmitted through the other side of the pipe 50 and by of connection 60. The two sides of pipe 50 are kept separate by a central block. The action of the apparatus is as follows:- The shaft 22 rotates in an anti-clockwise direction, Fig. 3, causing the left hand arm 34a of lever 34 to bear downwardly on arm 38 and moves it anticlockwise so that the stop 39 bears on the top of the pile. Air is then blown by the nozzle 51 to fluff up the edges of the sheets. Air pressure is also applied to cylinder 58 thereby raising the members 57. Suction is then applied to cylinder 40 so that sucker 43 is projected and grips the top sheet. As soon as a sheet is gripped the sucker rises as described and lifts the sheet gripped. The air pressure from nozzles 51 and cylinder 58 is then cut off, so that members 57 descend to hold the next-to-top sheet and to deliver a blast of air under the top sheet. The shaft 22 then rocks clockwise allowing arm 38 to lift under spting action so that roller 46 engages horizontal rail 31. As arm 38 rises the stop 39 is lifted from the top of the pile and the sucker 43 also rises carrying the top sheet with it. The clockwise rotation of shaft 22 continues until arm 34b bears against the other side of arm 38 and displaces the arm towards the left carrying the sucker and sheet in a substantially horizontal path so that its forward edge is inserted between the rollers 11, 12 which feed it to the machine. The suction is then cut off, the spring in the cylinder 40 holding the sucker raised until the sheet is completely removed. After the sheet has been taken by rollers 11, 12 the shaft 22 swings back and allows the arm 38 to return to the initial position in readiness for the next operation. If the collapsing sucker is of another type the gripper mouth may be held in the raised position by a guide rail during the return movement of the arm 38. The edges of the members 57 are curved or lie at an oblique angle to the edge of the sheets so that on the downward movement they " flip" past the edge and tend to separate the top sheet from any underlying ones which may have lifted with it. Specifications 763,831 and 763,832 also are referred to.