Abstract:
A method for producing bound books, magazines or brochures by gathering printed sheets into non-bound book blocks along a conveying section that is supplied by at least one sheet feeder includes separating the lowest printed sheet from a stack of printed sheets by lifting one edge region of the lowest printed sheet from the bottom of the printed sheet stack, withdrawing the separated lowest printed sheet with the aid of a conveying element from the remaining sheet stack by gripping the separated edge region with the conveying element, and subsequently withdrawing the separated lowest printed sheet in a direction parallel to the longitudinal extension of the edge region of the remaining sheet stack. The apparatus includes a separating device that lifts up the printed sheet at the stack front and a conveying element that pulls the printed sheet from the stack where both are arranged jointly on a removal unit.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application claims the priority of European Patent Application No. 03405710.9, filed on Oct. 2, 2003, the subject matter of which is incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   One exemplary embodiment of the invention relates to a method for producing bound books, magazines or brochures by gathering printed signatures into unbound book blocks along a conveying section that is supplied by at least one sheet feeder, wherein the printed signatures or sheets are respectively lifted up along one edge region at the front of the printed sheet stack and are then withdrawn from the stack by means of a conveying element. Another exemplary embodiment of the invention also relates to an apparatus for producing bound books, magazines, or brochures by gathering printed signatures along a conveying section, the apparatus comprising a conveyor provided with carriers and at least one feeder, arranged above the conveyor, which supplies the latter with printed signatures or sheets removed from a stack front. The feeder in turn is provided with a separating device, which lifts up an exposed edge region of the printed signature or sheet on the front of the stack, as well as a conveying element that pulls the printed signature or sheet off at the stack front. 
   Swiss patent document CH 692 700 A5 discloses a gathering and collating machine provided with a series of feeding stations, which respectively comprise a magazine for receiving a stack of printed sheets and a device for separating the respectively lowest printed sheet. The gathering and collating machine furthermore comprises a gathering conveyor with driven carriers in a gathering channel to which the separated printed sheets are supplied for the stack formation. For one embodiment according to CH 692 700 A5, the stack of printed sheets is positioned above the gathering channel on a conveyor belt, provided with suction openings, wherein one side region with fold is left exposed in the printed sheet-conveying direction. The underside of the printed sheet is advanced far enough with the suction belt, so that it can be transported further by a subsequently installed withdrawing conveyor. Compressed air can be supplied via the lowest printed sheet that is slanted toward the side by means of the suction element for reducing the friction between the printed sheet to be pulled off and the one positioned above. A so-called pass-through guide is provided at the magazine discharge opening, which can be used to form an adjustable pass-through gap above the conveyor belt, so that respectively only the lowest printed sheet with fold is pulled from the stack. 
   This known separating device can be used for feeding sheets in longitudinal as well as transverse direction to the gathering channel. 
   One disadvantage of this separating device, however, is that the pass-through gap on the magazine discharge opening must be adjusted for holding back the subsequently arriving sheet. This operation results in considerable expenditure not only for thin printed sheets with folds, but for small format printed sheets with folds as oftentimes the small format printed sheets with folds do not have a large enough area of contact with the conveying belt, thus making a reliable separation impossible. 
   SUMMARY OF THE INVENTION 
   In order to provide reliable separation and careful handling of printed signatures or large sheets, it is an object of the present invention to create a simple device which makes possible the uninterrupted separation of printed signatures or large sheets from a stack. 
   In one aspect of the invention, a method for producing bound books, magazines or brochures by gathering printed sheets into non-bound book blocks along a conveying section that is supplied by at least one sheet feeder is described. The method includes separating the lowest printed sheet from a stack of printed sheets by lifting one edge region of the lowest printed sheet from the bottom of the printed sheet stack, withdrawing the separated lowest printed sheet with the aid of a conveying element from the remaining sheet stack by gripping the separated edge region with the conveying element, and subsequently withdrawing the separated lowest printed sheet in a direction parallel to the longitudinal extension of the edge region of the remaining sheet stack. 
   In another aspect of the invention, an apparatus for producing bound books, magazines or brochures by gathering printed sheets along a conveying section includes a conveyor and at least one sheet feeder that is arranged above the conveyor and supplies the conveyor with printed sheets, which are individually removed from a front of a sheet stack, wherein the sheet feeder includes a separating device for separating an exposed edge region of the lowest printed sheet from the front of the sheet stack front and a conveying element that withdraws the separated, lowest printed sheet from the remaining sheet stack front wherein the separating device and the conveying element are jointly arranged on a removal unit. 
   Thus, according to an aspect of the invention, the foregoing object is achieved in that the edge region of a printed signature or sheet is gripped by the conveying element for lifting it off the stack and is subsequently pulled off the stack parallel to the longitudinal extension of the edge region, wherein the separating device and the conveying element are jointly arranged on a removal unit. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing and other features and advantages of the invention will be apparent from the following description of an exemplary embodiment, as illustrated in the accompanying drawings to which we expressly refer for all details not mentioned in the description, wherein the drawings show as follows: 
       FIG. 1  illustrates portions of a three-dimensional view of a device according to one embodiment of the invention; 
       FIG. 2  is an enlarged view of a feeder for the device according to  FIG. 1 ; 
       FIG. 3  is an enlarged view of detail X in  FIG. 2  showing a conveying device installed downstream of the printed sheet feeder; 
       FIGS. 4   a - 4   c  are sequential views of functional processing steps of the conveying element on the feeder; and 
       FIG. 5  is a partial view showing a mechanical drive for the removal unit for separating out a printed sheet from the stack. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows a device  1 , also called a gathering and collating machine, which basically includes a conveyor  2  with carriers  3  and sequentially arranged sheet feeders  4 , installed above conveyor  2 . Sheet feeders  4  may supply conveyor  2  with printed sheets  5  approximately in the conveying direction F. 
   However, the printed sheets could also be supplied perpendicular to conveying direction F by sheet feeders  4 , in a manner known per se, thereby changing the conveying direction of printed sheets  5  inside the conveyor  2 . 
   The carriers  3  are mounted on an endless traction element (not shown herein) and function to convey loose (unbound) book blocks  6  that are formed with printed sheets  5  through a conveying channel  7 , on the side viewed as the back side as seen in conveying direction. The conveying channel is provided with an upright guide wall  8  on the right side, as seen in conveying direction F. 
   The sheet feeders  4  are provided with a magazine  9  in which the printed sheets  5  are stacked on top of a magazine bottom  10 . 
   The magazine bottom  10  is provided with an approximately rectangular opening  11  at one side end of magazine  9  for removing the respectively lowest printed sheet  5  in the stack from the magazine  9 , wherein the opening  11  is shown in  FIGS. 1 and 4   a  to  4   c . The magazine bottom  10  is designed to have compressed air openings  12  through which compressed air is supplied from the underside of magazine bottom  10  to the area between the magazine bottom  10  and the printed sheet stack. As can be seen, magazine  9  is designed to be format-adjustable. 
   In an exemplary embodiment of the invention, printed sheets  5  are stacked inside magazine  9  and are provided with a final fold on the right-hand side, as seen in conveying direction F. 
   A driven removal unit  13  is provided as a separating device, which respectively grips an exposed edge of the lowest printed sheet  5 , having a fold herein, through the opening  11  in the magazine bottom  10 . Following the withdrawal of a printed sheet  5 , the removal unit furthermore takes on the function of the conveying element. The displacement movements of the removal unit for transporting the lowest printed sheet  5  out of the magazine are controlled, for example, by cam drives or linear drives. 
   Removal unit  13  functions as a separating device and includes a convex support surface  14  disposed along the opening  11 . Convex support surface  14  contains suction openings  15  that are connected to a vacuum source and aids in the separation of a printed sheet  5  from a stack of printed sheets. Support surface  14  removes the printed sheet  5 , which is held in place by a vacuum in the edge region of the support surface  14 , from the stack with the aid of a roll-off movement as illustrated in  FIG. 4   b . That is to say, the removal unit  13  carries out a combination rotation and translation movement for this separation. For this purpose, the support surface  14  of the removal unit  13  is provided with a circular surface, formed by a rotational axis  16  of the rotational movement. Convex support surface  14  moves at the level of the magazine bottom  10  or at a minimum distance above it during the separation operation. 
   Distributed along the front end of support surface  14  of removal unit  13  are several blow nozzles  31 , which are activated as soon as the suction through openings  15  starts, so as to supply blast air between the individual printed sheets  5  in the lower region of the sheet stack. This is designed to support the separation operation which has higher requirements, especially for thin or porous printed sheets. 
   The translational movement of removal unit  13 , horizontal and crosswise to the longitudinal extension of the fold edge herein, takes place along a stationary spur and/or toothed rack  30  that meshes with a spur gear and/or toothed segment  17  which is connected to removal unit  13  at rotational axis  16 . 
   With a subsequent translational movement of removal unit  13  in conveying direction F, the lowest printed sheet  5  in the stack that is held by suction is pushed out of the magazine  9  with the aid of blast air, supplied to the top side of magazine bottom  10 , so that it can be taken over by a downstream connected transporting device  18 . 
   The printed sheet  5 , which rests with its edge region on support surface  14 , is thus provided with a higher rigidity which has proven advantageous for preserving the form when it is pushed out of magazine  9 . 
     FIGS. 4   a  to  4   c  show the individual steps for the separation operation. The removal unit  13  according to  FIG. 4   a  is in a starting position, directly below the lowest printed sheet  5  to be separated from the stack in the edge region. In this extreme position of removal unit  13 , the printed sheet is held against support surface  14  with a small edge region by means of a vacuum that starts at openings  15 . Support surface  14  may be provided with several rows of suction openings  15  that may be arranged side-by-side in the withdrawing direction of the lowest printed sheet  5 . The removal unit  13  is subsequently turned clockwise and is simultaneously also displaced in a horizontal direction to the left (see  FIG. 4   b ). The edge region of printed sheet  5  (see also  FIG. 4   c ), which is held with increasing force against support surface  14  by the removal unit  13 , is bent toward the bottom while the position of the lowest printed sheet  5  above the magazine bottom  10  remains unchanged for the moment. As a result of the rolling off movement of the removal unit  13 —which occurs in planes that are perpendicular to the movement for withdrawing the printed sheets  5  from the magazine  9 —the adhering effect of the printed sheet  5  edge region at the withdrawing unit of removal unit  13  ( FIG. 4   b ) increases as a result of the activation of additional suction openings  15  on support surface  14 . 
   The removal unit  13  equals at least approximately the length of the edge region of the largest printed sheet to be gripped. 
   To ensure that the edge region quickly separates from support surface  14 , compressed air can be supplied via the suction openings  15  to removal unit  13  just prior to transferring the printed sheet  5  to the transporting device  18 . The compressed air helps separate the printed sheet  5  from support surface  14  once the vacuum is turned off. During the separating operation with the removal unit  13 , a support element  19  is pivoted from below against the exposed edge of the remaining stack. That is, support element  19  may be inserted into the gap formed by the separated printed sheet  5  and the remaining stack. The support element  19  is provided at the supporting end with a support surface  20  for lifting the remaining stack over the length of the edge region slightly off the lowest printed sheet  5  and is designed to have openings  21  along its edges for supplying compressed air to the stacked printed sheets. Support surface  20  may be planar. As shown in  FIGS. 4   a  to  4   c , it is possible to supply compressed air via the support element  19  into the gap, formed by the separated edge region of printed sheet  5  and the remaining stack of printed sheets. The compressed air reduces the friction between the lowest printed sheet and the remaining stack, thus further reducing the friction during the withdrawal of the lowest printed sheet  5 . In another embodiment, a planar support  20  may be provided with suction openings that face the remaining stack and are coupled to a vacuum source. 
   A gripping device  22 , which is mounted on removal unit  13  and extends over the length of the edge region of a printed sheet  5  that can be gripped, can be used to press a printed sheet  5  with additional force onto support surface  14 . The gripping device  22  comprises several gripping arms  23  which can be mounted, for example, on a controlled gripper shaft  24 . The gripper shaft  24  is connected to a controlled belt drive gear  25 . 
   Along the edge region of printed sheet  5 , the removal unit  13  is provided with several rows of suction openings  15  which can be activated with the approach of support surface  14 . 
   The downstream connected transporting device  18 , which is driven synchronously with the removal unit  13  in the withdrawing direction, discharges with a conveying end onto the conveyor  2 . The transporting device  18  comprises two conveying belts  26 ,  27 , driven to circulate endlessly around deflection rollers  28 ,  29 , wherein two adjacent conveying belt sections form a conveying gap for the printed sheets  5  fed in by the removal unit  13 . 
   The transporting device  18  is provided with a withdrawing device  32 , consisting of driven rollers  33 ,  34  that are arranged one above the other to form a withdrawing gap, wherein the withdrawing device  32  is installed upstream of the deflection rollers  28 ,  29 . The lower roller  33  is stationery while the upper roller  34  is advanced flexibly and with the timing of the printed sheet feeder  4  against the lower roller  33 . A drive element  35 , shown as linear drive herein, functions to move the upper roller/rollers  34  toward or away from the lower roller(s). 
   The rollers  33 ,  34  are driven so as to be rotated by two belt drives  36 ,  37  with respectively assigned gearwheels  38 ,  39 , which engage. 
   Of the rollers  34 , the rear roller  34 ′ in  FIG. 3  may be axially adjustable, so that it can be adapted to different printed sheet formats. In an exemplary embodiment, rollers  33 ,  34  may grip the withdrawn printed sheet  5  exclusively in the flat surface area. 
   As a result of the conveying gap in the transporting device  18 , formed by conveying belts  26 ,  27  and slanted in conveying direction  2 , removal unit  13  and magazine  9 , arranged above it, could also be slanted in the conveying direction. Thus, the printed sheet  5  which is moved by the removal unit  13  across the magazine bottom  10  is supplied in a straight line to the intake gap of the transporting device  18 . The withdrawing direction of removal unit  13  is approximately in the same direction as the conveying direction of conveyor  2 . 
   A retaining element  40  is arranged to the side of opening  11  to prevent the lowest printed sheet  5 ′ in the remaining stack from being carried along as a result of friction and due to a slight hanging in the edge region (as shown with dash-dot line in  FIG. 4   b ) when the lowermost printed sheet  5  is removed. This retaining element projects below the level of the magazine bottom  10  and thus forms an extended guide for the remaining printed sheets in the stack. The retaining element  40  is arranged at the back end of the magazine  9 , as seen in ejection direction, and is in a lower end position no later than at the start of the ejection operation, which prevents a multiple withdrawal of printed sheets from the remaining stack. The retaining element  40  moves in time with the withdrawal cycle for printed sheets  5  by oscillating in perpendicular direction. 
   For an uninterrupted return movement of the removal unit  13 , during which a reversible rolling-off movement also takes place, the retaining element  40  must be retracted toward the top by element  42 . 
   The operational steps required for transferring the printed sheet to the transporting device  18  are as follows: 
   The printed sheet  5  which adheres to the removal unit  13  is pushed out from under the remaining stack and into the conveying gap, formed by rollers  33 ,  34 , and/or into the transporting device  18 . The removal device  13 , the withdrawal device  33 ,  34  and the transporting device  18  all operate at the same conveying speed. 
   The removal unit  13  briefly accompanies the printed sheet, the vacuum is then turned off, and the reversal of the removal unit  13  to the starting position is subsequently initiated. With the vacuum turned off, the suction openings  15  could also be used to supply blast air to facilitate the separation of the printed sheet  5  from the removal unit. 
   To support the operation of separating the lowest printed sheet  5  from the remaining stack, the removal unit  13  is provided with blast air nozzles  31  that are distributed over the front end of support surface  14  and face the lower stack region. 
   The invention has been described in detail with respect to preferred embodiments, and it will now be apparent from the foregoing to those skilled in the art, that changes and modifications may be made without departing from the invention in its broader aspects, and the invention, therefore, as defined in the appended claims, is intended to cover all such changes and modifications that fall within the true spirit of the invention.