Patent Publication Number: US-6708968-B2

Title: Device for gathering flat articles into stacks and for further processing the stacks

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention is related to the field of materials handling technology and concerns a device for continuously gathering flat articles in a serial production of article stacks and for further processing the produced stacks. 
     2. Description of Related Art 
     In the printing and book-binding industry it is known to produce stacks of sheets, stacks of folded sheets, stacks of signatures or stacks of other printed products by providing a row of feed points, by conveying stacks being produced along the row of feed points one after the other in a substantially continuous manner and by adding one printed product to each stack at every feed point. The device for conveying the stacks being produced comprises, for example, a plurality of essentially V-shaped pockets arranged one behind the other. These pockets have upwardly-directed openings that extend substantially transverse to the conveying direction and the printed products are introduced into the pockets with one edge leading. A stack already present in the pocket is leaning against one of the walls of the pocket and, if so required, is pressed against this wall with suitable means, so that the product to be added can be introduced securely and precisely. For the same purpose, it is also possible to provide L-shaped stack supports arranged one behind the other, each respectively with a supporting surface and a foot element, wherein the supporting surfaces extend transverse to the conveying direction and advantageously are inclined relative to vertical. The supplied printed products are advantageously laid onto these supporting surfaces being guided at their leading edge, as is described, for example, in the Swiss patent application No. 2525/00 of the same applicant. 
     It is also known to remove the stacks of flat articles gathered in the manner briefly outlined above from the V-shaped pockets by opening the bottom of the pockets and letting the stacks fall out of the pockets driven by gravity. 
     In the publication EP-0908408 it is proposed to open such gathering pockets after completion of the stacks during continuous conveyance at their bottom, so that gravity relocates the stacks into lower pockets arranged to adjoin the gathering pockets. The walls of the lower pockets are movable such that the dropped stack is capable of being clamped between these walls, and so that when opening this pocket, the bottom side of the stack or all bottom edges of the flat articles gathered in the stack become freely accessible while the stack is being gripped in the lower pocket. For being bound, the exposed side of the stacks are then, for example, roughened, trimmed and/or treated with adhesive. Following this treatment, the stack is released by the pocket walls and dropped in a controlled manner. 
     Gathering of printed products in pockets being substantially continuously conveyed, is described also in the publication EP-0712736. Each finished stack is then clamped and gripped by the walls of the pocket such that the pocket can be opened at the bottom and the position of the stack remains unchanged relative to the pocket walls. The pocket comprises a U-shaped base part, which, for opening the pocket, is moved away downwards. The article edges on the bottom side of the stack being exposed in this manner are further treated for binding the stack, for which purpose the stack together with the clamping pocket walls is inserted into clamping tongues. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to create a device for continuously gathering flat articles into stacks and for further processing the stacks, with which device specific edges of the stacked, flat articles are aligned to one another during stacking and are made accessible for further processing on the finished stack and with which device the stacks with the exposed edge zones are conveyed to a processing operation. The device according to the invention differs from known devices with the same purpose, particularly by being more universally utilisable and simpler and by being significantly more easily adaptable to different requirements with respect to the exposure of the edge zones of the stacked, flat articles. 
     The device in accordance with the invention comprises, in a per se known manner, a plurality of stack supports that are substantially continuously conveyed one after the other in a conveying direction. These stack supports are essentially continuously conveyed, first, for producing the stacks by gathering articles, along a row of feed points, then through an exposure zone and from there to further processing. 
     The stack supports have supporting surfaces substantially aligned transverse to the conveying direction and foot elements arranged at the bottom end of each supporting surface. The foot element is actively connected to the supporting surface such that it is capable of being pressed against the supporting surface with a pressing force and such that by the action of suitable control means or by stopping the pressing force it can be spaced from the supporting surface and from this spaced position is able to be released again into the pressing position. 
     During the gathering operation, the flat articles are laid against the advantageously inclined supporting surfaces and their bottom edges are aligned to one another by the foot element, which in this phase is pressed against the supporting surface. The supporting surface and foot element together carry the stack in a defined position during production and after completion. 
     Downstream the last feed point there is an exposure zone, through which the stack supports are conveyed in substantially the same manner as along the row of feed points. Also conveyed through the exposure zone are stack support means and this in synchronism with the stack supports and aligned to them, wherein the conveying path of the stack supports and the conveying path of the stack support means are designed such that, at the entrance to the exposure zone, the stack support means are arranged immediately underneath the stack supports and such that, during conveyance through the exposure zone, they move more and more away downwards from the stack supports. 
     Furthermore, means for controlling the foot elements are provided in the exposure zone. A first such control means spaces the foot elements from the supporting surfaces at the point in which the stack support means are moving immediately underneath the stack supports, i.e. at the entrance of the exposure zone, such that the stacks lying against the supporting surfaces are released downwards and, still lying against the supporting surfaces, slide down onto the stack support means. The stacks are further conveyed lying against the supporting surfaces and supported by the stack support means until, as a result of the divergence of the conveying paths of stack supports and stack support means, they have slid off the stack supporting surface to such an extent that the bottom edges of the stacked flat articles protrude from the bottom edges of the supporting surfaces by a predefined value. At this point, a second control means releases the foot elements from their position spaced from the supporting surface to their pressing position. Through their sliding the stacks are now positioned between the supporting surface and the foot element, i.e. the foot element when released into the pressing position is not anymore pressed directly against the supporting surface but against the stack, so that the stack is pressed between foot element and supporting surface and, therefore, is fixed in its position relative to the supporting surface. Further sliding of the stack is not possible anymore. 
     With the stack clamped between the supporting surface and the foot element, the stack supports are conveyed onwards, wherein their spatial orientation can now be changed, for example, by swivelling the stack supports relative to the conveying path or by changing the direction of the conveying path. Through such changes of the spatial orientation of the stack supports and the stacks of flat articles clamped in them, the aligned edge zones protruding beyond the supporting surfaces, which were originally oriented downwards, can be oriented to suit a following processing operation. 
     For releasing stacked, flat articles possibly processed in the area of the exposed edge zones, from their clamped position in the stack supports, the part of the stack protruding between the supporting surface and the foot element can simply be taken hold of with suitable means and then the foot element can be brought back into its position spaced from the supporting surface. 
     Instead of L-shaped stack supports as described above, the device according to the invention may also comprise V-shaped gathering pockets extending substantially transverse to the conveying direction and comprising two pocket walls located opposite one another in the direction of conveyance. One of the pocket walls represents the supporting surface and the foot element closes off the distance between the pocket walls at the pocket bottom. 
     It goes without saying that using the device in accordance with the invention, it is not only possible to produce and further process stacks comprising a plurality of flat articles but it is also possible to clamp and further process individual articles, i.e. “stacks” comprising only one flat article. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and further features of the invention will be apparent with reference to the following description and drawings, wherein: 
     FIGS. 1 and 2 show, in two operational modes, the exposure zone of a first embodiment of the device in accordance with the invention; 
     FIGS. 3 to  5  illustrate in detail the operation of the foot element on the embodiment according to FIGS. 1 and 2; 
     FIGS. 6 and 7 show the exposure zones of two further, exemplary embodiments of the device according to the invention; and, 
     FIGS. 8 to  12  show the embodiment of the device in accordance with the invention as shown in FIGS. 1 and 2 in processing zones in which the stacks are held clamped between the supporting surface and the foot element. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 illustrates a first embodiment of the device according to the invention in the exposure zone  1 , through which stack supports  2  move substantially continuously (conveying direction F) and with essentially the same spatial orientation, in which they are conveyed along the row of feed points. Each of the stack supports  2  includes a supporting surface  3  and a foot element  4 . The stack supports  2  are coupled to a conveying organ (dot-dash line  5 ) by swiveling means  7  at equal distances between one another, as illustrated. They may also, however, be movable in the conveying direction F substantially independent of one another. The supporting surfaces  3  of the stack supports  2  extend substantially transverse to the conveying direction F (perpendicular to the paper plane of FIG. 1) and are arranged inclined in the conveying direction, such that, for example, their bottom edges trail the upper edges. 
     Each one of the stack supports  2  being conveyed into the exposure zone  1  carries a stack  6 , wherein the flat articles of the stack  6  were deposited in an as such known manner on the stack supports  2  during conveyance along a row of feed points arranged upstream of the exposure zone  1  illustrated in FIG.  1 . 
     Stack support means  10  are arranged to move through the exposure zone underneath the stack supports  2 , in synchronism with the stack supports  2  and aligned with the stack supports  2  such that, at the entrance to the exposure zone  1 , the stack support means  10  are positioned immediately underneath the bottom edges of the supporting surfaces  3  and such that, during their conveyance through the exposure zone  1 , the stack support means  10  moves away from the stack supports  2  at an acute angle. The stack support means  10 , for example, comprises individual stack support bases  11  coupled to a conveying organ  12  with a closed-in-itself circulation track. 
     At the point designated with A and approximately corresponding to the point at which the stack base supports  11  are situated closest to the supporting surfaces  3 , a first control means (not illustrated) is effective to bring the foot elements  4  of stack supports  2  being conveyed therepast into a position spaced from the supporting surface  3 . As a result, the stack  6  lying against the supporting surface  3  slides down onto the stack support base  11 . 
     During onward conveyance and due to the divergence of the conveying paths of the stack support  2  and the stack support base  11 , the stack  6  slides down further and more and more protrudes beyond the supporting surface  3 . 
     At the point designated with B and situated downstream of point A, a second control means (not shown) is arranged to release the foot elements  4  of stack supports  2  into their pressing position from their position spaced from the supporting surface  3 , in order to press the slid down stack  6  against the supporting surface  3  and to thus fix it in a position protruding beyond the supporting surface  3 . 
     In a zone downstream of point B, the stack support bases  11  are moved away from the stack supports  2 , as a result of which the bottom edge zones  13  of the stacked, flat articles, which protrude beyond the supporting surface  3  and the foot element  4 , become freely accessible for further processing of the stacks. 
     From FIG. 1 it is clearly evident, that the stack supports  2  are very simple device components that are capable of being conveyed along the conveying path following one another very closely. It is also evident, that the stack supports  2 , when holding a stack  6  clamped between supporting surface  3  and foot element  4  can be brought into various spatial orientations, for example by being swiveled by the swiveling means  7  parallel to the conveying path F and/or by changing the direction of the conveying path. In this way, the exposed, originally bottom edge zones  13  of the stacked, flat articles can be made optimally accessible for a processing operation or for transfer to a further conveying device. 
     From FIG. 1 it is also evident that the device according to the invention is very easily adaptable for different handling operations of different stacks. Within the broadest limits it is of no importance how large (also how differently large) and how numerous the stacked, flat articles are. As long as they each have a substantially straight edge zone and as long as this edge zone of all articles to be stacked are to be aligned to one another, the device can be used without any modifications. For adjusting the length, by which the bottom edge zones  13  in their exposed condition are to protrude beyond the supporting surface  3 , advantageously the point B or the second control means, respectively, is moved along the conveying path F (arrows C). On the other hand, it is also possible to adjust the angle between the conveying path F of the stack supports  2  and the conveying path of the stack support bases  11 . 
     The stack support bases  11  illustrated in FIG. 1 extend, parallel to the supporting surfaces  3  and the foot elements  4 , substantially transverse to the conveying direction F and comprise a floor surface, which advantageously is aligned perpendicular to the supporting surfaces  6 . With stack supports  11  of this kind, the stacks  6  obtain a rectangular shape. In cases in which such rectangularity is not relevant, it is also possible for a very simple conveyor belt to take over the function of the individual stack support bases illustrated in FIG.  1 . 
     FIG. 2 illustrates essentially the same device as FIG.  1 . While the device in accordance with FIG. 1 is operated in a mode in which the foot elements  4  of all stack supports  2  being conveyed past point A are actuated, according to FIG. 2, only selected ones of the stack supports  2  are actuated. For example, only stack supports that contain an error-free stack  6  are actuated. Stack supports  2  that are not actuated are conveyed through the exposure zone  1  in an unchanged condition. 
     For controlling the operating mode according to FIG. 1, the control means are, for example, stationary cams co-operating with guide rollers arranged on the foot elements  4  of the stack supports  2 . For controlling the operating mode according to FIG. 2, active control means have to be provided to selectively actuate control elements acting on the foot elements  4  of the selected stack supports. 
     FIGS. 3 to  5  show in more detail the operation mode of an exemplary embodiment of a stack support  2  in the device illustrated in FIGS. 1 and 2. Illustrated are the bottom zones of a stack support  2  in a configuration suitable for the gathering operation (FIG.  3 ), suitable for the exposure of the bottom edge zones  13  of the stacked, flat articles or for releasing a stack (FIG. 4) and suitable for further processing the stack  6  or the exposed edge zones  13  of the stack respectively (FIG.  5 ). 
     In each of FIGS. 3-5, the bottom part of the supporting surface  3  is limited on both sides by side pieces  20  (only one shown), and a stack  6  is shown lying against the supporting surface  3 . The foot element  4  is fixed to the side pieces  20  so as to be capable of swivelling and is driven against the supporting surface  3  by a tension spring  21  pre-tensioned between the side piece  20  and the foot element  4 . The foot element  4  further comprises a guide roller  22 , which, when rolling on a corresponding cam surface  23 , brings the foot element  4 , against the tensile force of the tension spring  21 , into a position more or less spaced from the supporting surface  3  and holds it in such a position. The cam surface  23  is necessary in zones of the conveying path (FIG. 4) in which the foot elements  4  have to be held in a position spaced from the supporting surface  3 . The cam surface  23  can be absent in zones of the conveying path (FIGS. 3 and 5) in which the foot element  4  is pressed against the supporting surface  3  or against a stack  6  lying against the supporting surface  3  with the full force of the tension spring. 
     FIG. 3 depicts the foot element  4  in the gathering configuration, into which it is driven by the force of the tension spring  21 , when no stack  6  is positioned between the supporting surface  3  and foot element  4 . In this position, the foot element is tightly joined with the supporting surface  3  such that it is capable of supporting flat articles lying against the supporting surface  3 . 
     FIG. 4 illustrates the stack support  2  in the exposure or release configuration, in which it is conveyed through the exposure zone, i.e. through the zone between points A and B depicted in FIGS. 1 and 2, and through a release zone, in which a stack is released from the position clamped between supporting surface  3  and foot element  4 . The foot element  4  is spaced from the supporting surface  3  such that the bottom end of the supporting surface  3  is free and flat articles lying against the supporting surface  3  can slide down along it or are able to be removed from between the supporting surface  3  and the foot element  4 . During conveyance, the foot element  4  is held in this position by the cam surface  23  and the guide roller is pressed against the cam surface by the spring force of tension spring  21 . 
     FIG. 5 illustrates the stack support  2  in the processing configuration, into which it is brought, when stacks  6  lying against the supporting surface  3  and being supported by the stack support means (not depicted) have slid beyond the supporting surface  3  by a predetermined amount (point B in FIGS.  1  and  2 ). The foot element  4  is pressed by the tension spring  21  against the stack  6  and is firmly holding the stack. 
     Instead of the tension spring  21 , it is possible to use other means to press the foot element  4  against the supporting surface. This function, for example, may also be taken over by the guide rollers  22  and a corresponding cam surface. For the operating mode illustrated in FIG. 2, cam surfaces are not suitable control means. In this case, active control means selectively unlatching the tension spring  21  have to be provided. 
     FIGS. 6 and 7 illustrate two further, exemplary embodiments of the device according to the invention. 
     The stack supports  2  according to FIG. 6 each have an extension  30  on the supporting surface  3  and a foot element  4  running substantially parallel to one another in a downwards direction and forming a sort of flat pliers for holding the stack  6  even better than is possible with the embodiment according to FIGS. 1 and 2. 
     FIG. 7 very schematically illustrates a further, exemplary embodiment of the device according to the invention, in which the supporting surfaces  3  and foot elements  4  form components of substantially V-shaped gathering pockets  2 ′. The foot elements  4  are each connected in an articulated manner to a pocket wall  31  situated opposite the supporting surface  3  and are driven into a “closed” position by pressing means (not shown) and into an “open” position by suitable control means. 
     FIGS. 8 to  12  illustrate the embodiment of the device according to the invention as depicted in FIGS. 1 to  5  in a conveying zone downstream of the exposure zone. In this zone, the stacks  6  are further processed by action on the edge zones  13  of the flat articles. This further processing has to be understood in a very broad meaning of the term. It shall not only include steps modifying these edge zones (for example by binding of a stack of printed products), but may also be a pure handling operation (for example a transfer to a further conveying device) or may be both. 
     FIG. 8 illustrates a stack handling operation substantially consisting of reversing the exposure of the bottom edge zones  13  possibly after processing these edge zones  13 . The stack supports  2  hold stacks  6  pressed between the supporting surfaces  3  and foot elements  4  when conveyed into this zone, in which further stack support means  10 ′ with stack support bases  11 ′ conveyed parallel to the stack supports  2  are provided. These stack support bases  11 ′ are adjustable in their height relative to a conveying organ  12 ′ in such a manner and to such an extent, that they are capable of pushing back stacks  6  along the supporting surface  3 . In analogy to the exposure zone, a first control means is provided for driving the foot elements  4  at a point A and, at a point B, a second control means is provided. The first and second control means, as already described in connection with FIG. 1, act on the foot elements  4  of all stack support  2  conveyed past or only on the foot elements  4  of selected ones of the stack supports  2  (as illustrated in FIG.  8 ). 
     For a processing operation as illustrated in FIG. 8, it is a prerequisite that the stack support bases  11 ′ and the foot elements  4  are designed such that they are able to mesh with one another. The stack support bases  11 ′ therefore, for example, comprise gaps along their extent transverse to the conveying direction or else are narrower than the stacked articles, and the foot elements  4  consist of at least two foot element components, which are aligned to the named gaps or else are arranged lateral to the stack support bases  11 ′. 
     FIGS. 9 to  11  illustrate transfer zones in which stacks held clamped between supporting surfaces  3  and foot elements  4  are transferred to a further conveying means  40 . To achieve this, at a point A of the conveying path F a first control means is provided for bringing the foot elements  4  of stack supports  2  conveyed past into the position at a distance from the stack supporting surface  3 . 
     In accordance with FIG. 9, the further conveying means  40  comprises grippers  41  for gripping the exposed edge zone  13  before the stack supports  2  are conveyed past point A. According to FIG. 10, the taking over conveying means  40  comprises pockets  42 , in which covering sheets  43  may already be positioned. The exposed edge zones  13  are inserted into these pockets as far as possible before the stack supports  2  pass point A, where the stacks  6  are released by actuation of the foot elements  4  and are left to fall into the pockets. For this case it is particularly advantageous if the stacks  6  protrude beyond the supporting surfaces  3  as far as possible, such that free fall is as short as possible. 
     According to FIG. 11, the exposure zone  1  and the transfer zone substantially coincide. Already during the exposure of the bottom edge zones  13  in the exposure zone  1  while sliding along the supporting surfaces  3 , the stacks  6  are inserted into clamping means  50  of a further conveying means  40  and downstream of the exposure zone they are gripped by the clamping means  50 , and then released by the foot elements  4 . 
     FIG. 12 illustrates further processing of stacks  6  held clamped in stack supports  2 , the processing regarding the area of the exposed edge zones  13 . The stacks  6 , which at least in the exposure zone are downwardly directed, are brought into a vertical position in which the exposed edge zones  13  are oriented upwards by a change  60  of the conveying direction F of the stack supports  2  and a corresponding swivelling of the stack supports  2  relative to the conveying path. With the new stack orientation, the stack supports  2  are conveyed through a processing zone for further processing of the stacks  6  and then through a release zone. In the processing zone, folded covering sheets  43  are opened and laid over the exposed edge zones. In the release zone, the exposed edge zones  13  with covering sheets  43  laid over them are gripped by suitable grippers and are released by the foot elements  4  (point A). 
     Prior to the placement of the covering sheets  43 , the exposed edge zones, if so required, may be roughened or trimmed and treated with adhesive. After placement of the covering sheets  43 , they may be correspondingly pressed. It is also conceivable to apply more than one covering sheet  43  and, prior to releasing the stacks  6 , to tack the multitude of covering sheets together.