Patent GB-763831-A (GB)
Title: Improvements in sheet separating and forwarding devices
Inventor: TEBBS GEORGE WILLIAM
IPC: B65H3/08
Filed: 1953-06-01
Abstract: 763,831. Feeding sheets. BACKHOUSE, H. T. Sept. 1, 1954 [June 1. 1953], No. 15151/53. Class 100(1). Apparatus for separating sheets from the top of a pile comprises a stop 39, Fig. 3 arranged to bear on the top of the pile adjacent one edge thereof or to be held a short distance above the top of the pile, 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 thereby to bend the sheet about the stop, means to lift the stop from the pile, means to move stop and the gripper still holding the sheet, in a direction over the pile and then, after release of the sheet, to return the stop and gripper 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 so that the mechanism may be adjusted in position according to the size of sheet being separated. 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 bar is supported at each end on interconnected bell-crank levers pivoted to guide 15 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 two-armed lever 34 keyed to the shaft and a freely mounted lever 35, carrying an arched arm 38. The cylinder 40 of the collapsing 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 sucker 43 is rotatably mounted about an axis 44 and connected by a radius arm 45 to -the stop 39 which forms an extension of the arm 38. As the sucker rises it is rotated by the arm 45 to keep the mouth at a substantially constant angle to the sheet. The collapsing gripper 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, therefore, the piston rod will be projected against the action of the spring by the suction on 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 is. thereby bent about the stop 39, the mouth remaining normal to the part of the sheet gripped as described. A roller 46 carried on the arm 38 is adapted to bear against the underside of 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 prongs 57 constituting presser feet and air nozzles 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 a piston and cylinder 58 acting through a link 59. The action of the apparatus is as follows:- The shaft 22 rotates in an anti-clockwise direction, Fig. 3, so that the left hand arm 34a of lever 34 bears downwardly on arm 38 and moves it anti-clockwise against its spring so that the stop 39 bears on top of the pile. Air is now blown by the nozzle 51 to fluff up the edges of the sheets. Air pressure is also applied to cylinder 58 thereby raising the nozzles 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 blast from the nozzles 51 and cylinder 58 is then cut off, so that nozzles 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 so that arm 38 lifts under spring 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 rises further 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 the 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. During the movement to the left of the arm 38 one end is guided by lever 35 and the other by roller 46 rolling on rail 31. 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 gripper is of another type the sucker mouth may be held in the raised position by a guide rail during the return movement of the arm 38. Specification 763,832 also is referred to.