Patent Publication Number: US-6659448-B2

Title: Adjustable separator for a sheet separating device

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to apparatus for separating flat products from a pile of flat products, and more particularly to an apparatus for separating flat products from a pile of flat products, the apparatus including adjustable separators supporting the bottom of a pile of flat products. 
     In the technology of creating books, including booklets, magazines, periodicals, and the like, the use of collating systems is well known. These systems typically have a transporting device on which individual flat products, such as signatures or sheets, are gathered to build a book-block set, which then is finished and bound. Typically, a number of feeders are arranged along the transporting device, each of the hoppers comprising a feeding mechanism for feeding an individual flat product from a pile of signatures onto the transporting device, in order to gradually build up the book-block set or to insert a supplement sheet into a pocket of a pocket feeder or into a newspaper arranged in the pocket. Such feeding mechanisms typically employ a sheet-separating device for separating a sheet or other single flat product from a pile of flat products which is arranged in each hopper. The single flat products are drawn from the pile at its bottom end. 
     A sheet-separating device of this kind is known, for example, from U.S. Pat. No. 3,988,016. This document describes a high-speed paper inserting apparatus for insertion of supplements into newspapers. The inserts are placed to form a stack and a vacuum gripping member grips the lowermost insert from the stack and carries it to a pair of nip rollers which transport the insert to an opened newspaper. A single sheet requires a different sucker stroke than a 120 page or pre-inserted section. The different sucker motion requirements are due to the way the sheets or sections have to be positioned and controlled for proper singulation. Generally, the bottom of the stack is supported by a platform, a so-called signature table having a recess for allowing a sucker to draw a single product from the lowermost end of the pile of products. When the sucker does not contact the pile of products, the pile is supported by a movable hook, as shown in U.S. Pat. No. 4,157,692. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to provide a sheet-separating device with improved separation of the lowermost product of the pile of products. 
     Commonly-owned U.S. Pat. No. 09/939,428 filed on Aug. 24, 2001 and claiming priority to U.S. Provisional Patent Application No. 60/226,247 filed Feb. 2, 2001, discloses using a plurality of movable needles for selectively supporting the bottom of a stack of signatures, the needles moving in and out of the stack about a pivot point. The penetration depth of the needles is adjustable. U.S. Pat. No. 09/939,428 is hereby incorporated by reference herein. 
     When the penetration depth of the needles of the &#39;428 device is adjusted, the contact point of the needles with an edge of the stack can vary, leading to separation problems. 
     The present invention provides an apparatus for separating flat products from a pile of flat products, the apparatus including a support and at least one separator for separating a product from a pile of products, the separator being movable with respect to the support, the separator including a curved surface for contacting an edge of the pile. 
     The curved surface permits a penetration depth of the separator to be set by rotation without significantly altering the contact position of the separator and the edge of the pile, which can improve separation. 
     Preferably, the curved surface defines an arc of a circle. Most preferably, the separator rotates about an axis, and the arc has a constant radius about the axis. 
     An actuating device can move the separator. 
     A plurality of separators, for example four or six, spaced along the edge of the pile preferably is provided, the separators being fixed to a rotating block. The rotating block rotates about the axis, and is actuated by the actuating device. 
     The axis is preferably located below the contact position, so that the curved surface is convex. 
     The present invention also provides a method for separating a bottom product from a pile of products comprising the steps of: 
     rotating a separator into the pile, the separator defining a penetration depth; and 
     adjusting the penetration depth without altering a contact point between an edge of the pile and the separator. 
     Preferably, the separator includes a curved surface. The curved surface preferably defines an arc of a circle. The separator preferably rotates about an axis, and the arc preferably is defined by a constant radius about the axis. The axis preferably is below the separator so that the curved surface is convex. 
     The present invention also a method for separating flat products from a pile of flat products comprising the steps of moving at least one separator for separating a product from a pile of products with respect to a support, the separator including a curved surface for contacting an edge of the pile. 
     Preferably, the curved surface defines an arc of a circle about an axis, the at least separator moving by rotation about the axis. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention is elaborated upon below with reference a preferred embodiment disclosed in the accompanying drawings, in which: 
     FIG. 1 shows a schematic side view of a preferred embodiment of the sheet separating device. 
     FIG. 2 shows a perspective top front view of the sheet separating device of FIG. 1, which can be attached to a hopper. 
    
    
     DETAILED DESCRIPTION 
     FIGS. 1 and 2 show the sheet separating device according to a preferred embodiment. The device may be attached to a hopper by bolts  26 , so that support  18  (or a part of the hopper such as a face plate connected to support  18 ) defines a front support for a stack of flat products  80 . Stack of flat products  80 , for example signatures, can lie flat on a signature table  22  of the hopper, with an edge of bottommost product  24  defining an edge or contact point  20  of stack  80 . 
     A lift hook and suckers may aid in the removal of the signatures. During the transition between closing and openings of the lift hook and sucker, the signature stack is supported by separators  10  selectively protruding through an opening in a front guide of the hopper. Preferably, there are multiple separators  10 , for example four or six evenly spaced along the edge of the stack. The separators  10  may be fixed by bolts to a rotating block  34 , which rotates about an axis  30  defined by a pivot  32  supported in support  18 , which is fixed with respect to the hopper. An actuating device  36  connects to the block  34  above the pivot  32  so as to permit rotation of the block  34  about axis  30 . 
     Separators  10  on block  34  thus can rotate in an out of the stack  80  so as to achieve a protrusion depth d. Separators  10  have a curved surface  12  for interacting with edge  20 , with the curved surface  12  forming an arc having a constant radius r with respect to axis  30 . The depth d needles  50  protrude through the face plate is important, because if the needles protrude too far, the sucker cannot effectively remove the signature  22 , and if the needles protrude too little, they will not effectively support the signature. 
     The protrusion depth d of the separators can be set by setting the stroke length of actuating device  36 , which may include a piston. 
     Due to the curved surface  12 , the intersection point  20  of the top level of the signature table  22  and the support  18  (or if support  18  is not the front plate, the front plate of the hopper) remains the same, even if the protrusion depth d is adjusted. 
     The axis  30  preferably is below the table  22 , so that a convex surface  12  results. However, a pivot point above the table  22  could also be possible. 
     “Support” as defined herein may be any part of the sheet separating device stationary with respect to the hopper or may be a part of the hopper itself. “Sheet” as defined herein can be any flat product including signatures.