Abstract:
Sheets or sets of sheets are turned very rapidly and reliably, especially after the cutting of endless stationery, conveyed further in a different transport direction and separated in that the leading edge of each sheet is taken to a diagonal bending slot ( 33 ) via which a corner of each sheet first reaches an output slot ( 49 ).

Description:
BACKGROUND 
     The invention relates to a device for turning a sheet with a simultaneous change in the conveying direction. Devices of this type are needed in case sheets or forms are transferred from a processing station, for example a printer or a copier, to a conveyor chain in order to be carried by the latter past further handling or processing stations, or to be composed, with additional sheets and forms, into a set of sheets or a set of forms. 
     A high operating speed is desirable when handling and processing sheets and forms, e.g. in mail processing machines. Disturbances, paper jams, and the like must be avoided since they can trigger a standstill of the entire facility and can lead to the destruction of documents which has grave consequences, for example, when processing bank mail. 
     Accordingly, it is an object of the invention to design a device for turning a sheet with a simultaneous change in conveying direction in such a way that a continuous flow of the sheets to be handled is ensured with a high operating speed, and breakdowns are avoided. 
     This object has been attained according to the invention by providing that the sheet is transported by means of a driving roller arrangement into an inlet slot defined by guide walls. The inlet slot meets a diagonally-extending bending slot, the axis of curvature of which is oriented substantially in parallel to the plane of the sheet and at an angle of preferably 45 degrees with respect to the leading sheet edge. The bending slot terminates in an outlet slot wherein outlet drive means are provided at least for seizing the sheet corner first entering the outlet slot. The outlet slot is located in a plane that is substantially parallel to the plane of the inlet slot, but spaced therefrom. 
     A multiple juxtaposition of devices of the type briefly described above makes it possible to turn a single sheet and discharge it with an altered conveying direction. It also permits independent processing of a plurality of sheets or form sections, (transported lying side-by-side in a plane) simultaneously with the turning step and the change in conveying direction. In this manner, after individual processing it is possible to correlate individual sheets or form sections, into separate sheet stacks or sets of forms. 
     SUMMARY 
     According to a preferred embodiment of the device proposed herein which, as mentioned above, can be provided in multiple juxtaposition, an inlet slot is formed between a cover plate and a guide plate. The cover plate includes a diagonally-curved rerouting flange extending into a diagonal recess of the guide plate to form a bending slot with the guide plate which exhibits a diagonal, substantially-cylindrical guide member located in opposition to the rerouting flange. Finally, the outlet slot and the outlet drive means are arranged on the side of the guide plate facing away from the cover plate. 
     Suitably, the outlet slot contains, on the one hand, sections of revolving conveyor belts traveling in the discharge direction and, on the other hand, counter-support roll elements, associated therewith, as the outlet drive means, wherein the roll elements are preferably formed by balls retained in cages of the guide plate. 
     It has proven to be advantageous to first convey the sheet or sheets to be handled into the zone of the drive roller arrangement in the inlet slot and, prior to passing the sheet or sheets on, to retain the latter, for example by means of a vacuum retaining unit, against the driving action of the driving roller arrangement. Only thereafter the sheet or sheets are released in a controlled fashion whereby a precise initial position of the respective sheet or sheets is attained during entrance into the rerouting slot. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments will be described in greater detail below with reference to the drawings wherein: 
         FIG. 1  is a schematic perspective view of a device for turning a sheet with a simultaneous change in conveying direction wherein certain supporting-frame parts have been omitted to simplify the illustration and to improve clarity, 
         FIG. 2  is a sectional view of the device taken along the lines II—II in  FIG. 1 , 
         FIG. 3  is a perspective schematic view of the route of several sheets to be separately processed in devices of the type set forth herein; and, 
         FIGS. 3a  to  3 d are schematic top views of ways of handling the sheets or forms, conveyed and turned in devices of the type disclosed herein, which are fed, for example in a mail processing machine, to a conveyor chain. 
     
    
    
     DESCRIPTION 
     Upstream of the device  10  in  FIG. 1  a feeding unit  11  is arranged so that a feeding slot  12  is formed between pairs of mutually-opposed guide bars  13  and  14 . The guide bars  13  can be held together by means of transversely extending connecting rods  15  ( FIG. 2 ) while the guide bars  14  are held together correspondingly by transversely extending connecting rods  16 . 
     Means arranged upstream of the feeding unit  11  transports a sheet, such as might be cut from an endless form by a cutter, into the feeding slot  12  in the direction of arrow  17 . The sheet is fed into the inlet slot  12  until the leading sheet edge projects past the feeding slot  12  and passes into an inlet slot  18  ( FIG. 2 ) for turning and changing the conveying direction. In this respect, a driving-roller arrangement  21  and  22  projects by way of cutouts of guide walls  19  and  20  into the inlet slot  18 . These rollers  21  and  22  seize the forward edge of the sheet  12  and pull it further into the inlet slot  18 . 
     Before the sheet to be handled has been pulled by the driving roller arrangement  21  and  22  completely into the inlet slot  18 , however, a vacuum retaining unit  23  ( FIG. 2 ) blocks further movement of the sheet. In this respect, the idler rollers  21  are freewheeling while the lower driving rollers  22  are driven by motor  24  of the driving roller arrangement, but rollers  22  are not equipped with a friction coating and do not overcome the retaining force of the vacuum retaining unit  23 . The vacuum of the retaining unit  23  is obtained from a vacuum source  27  and delivered through a control valve  26  and ducts  25  to vacuum retaining openings of the guide bars  14 . The respective sheet position at which the vacuum retaining unit  23  is turned on or deactivated is determined by means of a conventional position indicator  28  in the form of a photocell and a control unit  29 . 
     The guide walls  19  and  20  converge, in the manner shown in  FIG. 2 , from the inlet side toward the inlet slot  18 . The upper guide wall  19  and the rollers  21  are attached to a swivel yoke  30  which is swingable upwardly about a swivel axle  31  supported in bearing blocks  32  ( FIG. 1 ) to lift the upper guide wall  19  and the rollers  21  off the lower guide wall  20  and driving rollers  22 . In this manner, the inlet slot  18  is accessible. As can be seen from  FIGS. 1 and 2 , a diagonally-extending bending slot  33  is defined, on the one hand, by a diagonal, curved rerouting flange  34  of the upper guide wall and, on the other hand, by a diagonal, substantially-cylindrical guide member  35  located in opposition to the rerouting flange. The upper guide wall  19  and the lower guide wall  20  extend in the conveying direction of the driving roller arrangement up to the diagonally-extending bending slot  33 ; and, the axis of curvature of the slot  33  is oriented substantially parallel to the plane of the inlet slot and thus to the plane of the sheet to be handled. The illustrated slot  33  is at an angle of 45 degrees with respect to the leading sheet edge. 
     The upper guide wall  19  is thusly fashioned as a comparatively-rigid cover plate which projects into a diagonal recess of the lower guide wall  20 , oriented at 45 degrees to the conveying direction of the driving roller arrangement wherein the diagonal forward edge of the lower guide wall  20  is terminated by the guide member  35 . The lower guide wall  20  also forms the upper termination of a guide member  36 , a central layer  37  of which is comprised, for example, of polytetrafluoroethylene and is provided with cage recesses  38  wherein roll elements or balls  39  are accommodated. These balls are retained in the cage recesses  38  by means of a lower, end wall  40  of the guide plate  36 . The lower end wall  40  is equipped with conventional recesses of adequate diameter and oriented toward the cage recesses  38  in such a manner that the roll elements  39  project in the downward direction through the cutouts of the lower, end wall  40 . It can also be seen from  FIG. 2  that the central layer  37  of the guide plate  36  is provided with recesses in such a way that the driving rollers  22  of the driving roller arrangement can be accommodated therein. These rollers extend upwardly into the inlet slot  18  through the cutouts of the lower guide wall  20 . 
     A table  41  is located underneath the guide member  36  and the top sides of conveyor belts  42  and  43  are guided over this table as shown. These conveyor belts are placed over drive rollers  44  and  46  (driven by motor  48 ) and idler rollers  45  and  47  arranged at the beginning and at the end of the table  41  respectively. 
     The lower end wall of the guide plate  36 , on the one hand, and the table  41 , on the other hand, define an outlet slot  49  lying in a plane oriented in parallel to the plane of the inlet slot  18  and spaced therefrom by a distance corresponding essentially to the thickness of the guide member  36 . The upper sections or the upper faces of the conveyor belts  42  and  43 , on the one hand, and rows of roll elements  39  respectively aligned with the conveyor belts, on the other hand, are effective in the outlet slot  49  as the transport means. This relationship can be readily seen by one skilled in the art from  FIGS. 1 and 2 . 
     On the outlet side of the conveyor belts  42  and  43 , are a pair of casters  50 , indicated in dot-dash lines in FIG.  1  and located in opposition to the rollers  45  and  47 . Between the casters of the caster pair  50  a disk traveling therewith can be arranged. This is not shown in FIG.  1 . The disk is dimensioned in its diameter in such a way that it projects somewhat into the profile of the outlet slot  49  and thus imparts to the discharged sheet a slight transverse bulge whereby the stability of the discharged sheet is increased in a desirable fashion. 
     During operation, a sheet, cut off, for example, from an endless form, is introduced from a cutter in the direction of arrow  17  into the feeding unit  11  and advanced to such an extent that the forward edge of the sheet is finally seized by the driving roller arrangement ( 21 ,  22 ) in the inlet slot  18  and is further advanced in the inlet slot  18 . During this step, the rearward sheet-edge finally travels past a feeler  28  which produces a signal and causes a control unit  29  to activate the vacuum retaining unit  23  by opening the valve  26 . In this manner, at this point, the sheet is retained by the vacuum suction openings at the outer end of the ducts  25 , and the driving rollers  22  initially merely idle underneath the portion of the sheet that is present in the inlet slot  18 . 
     When the sheet is released again by closing the valve  26  and shutting off the vacuum retaining unit  23 , the driving roller arrangement  21 ,  22  pushes the sheet forward in the inlet slot so that initially the sheet corner located on the left in  FIG. 1  will reach the bending slot  33  and is bent downwards at an angle of 45 degrees. This continues until the sheet corner has reached the outlet slot  49  and is seized between the conveyor belt  42  and the ball denoted by  39 A in FIG.  1 . 
     The conveying speed of the conveyor belts  42  and  43  in conjunction with the roll elements  39  is preferably higher than the conveying speed of the driving roller arrangement  21 ,  22 . Hence, the sheet to be handled, as soon as its corner lying on the right in  FIG. 1 , is seized between the conveyor belt  42  and the roll element or the ball  39 A and is pulled with increased velocity from the inlet slot  18  into the outlet slot  49 . The initially-prevailing contact with the inside of the rerouting flange  34  is then changed to contact with the outer surface of the guide member  35  and the sheet precisely follows the diagonal bend of the guide member  35  in such a way that, based on the 45 degree orientation of the guide member  35 , the conveying direction of arrow  51  is obtained in the outlet slot  49  which is at 90 degrees with respect to the feeding direction of arrow  17 . 
     In practical embodiments of the device set forth herein and schematically shown in  FIGS. 3 ,  3 a,  3 b,  3 c, and  3 d, the feeding unit  11  as well as the unit  10  comprise several juxtaposed sections, wherein the swivel yoke  30  and the swivel axle  31  extend in one piece over these several sections and are equipped in each case with sets of rollers  21  corresponding to the arrangement shown in FIG.  1 . Cover-plate sections  19  with rerouting flanges  34 , respectively associated with the aforementioned sections, are attached to the swivel yoke  30  and extend over several sections. The rerouting flanges  34  enter in each case into diagonal recesses, provided with guide members  35 , of a guide plate  36  of a relatively great length extending in the transverse direction over all of the sections. On the underside of the guide plate  36  is the table  41  which also extends correspondingly over all of the sections of the device; and, correspondingly-lengthened conveyor belts  42  and  43  are extended over the topside of the table  41 . 
     The above-described device solves the problem of turning several sheets that are fed side-by-side in a plane and separated from one another in the longitudinal direction, and to individually process and discharge the sheets in a direction perpendicular to the feeding direction, as shown schematically in  FIGS. 3a-3d  and in a perspective view in FIG.  3 . After having been fed and turned and subjected to a change in the conveying direction, the handled sheets succeed one another in this new conveying direction in overlapping relationship. Sheet  52 d lying on)he right with reference to the illustration of  FIG. 3 , for example, is transported by the discharge unit as the uppermost sheet while sheet  52 a shown to lie on the left-hand side in  FIG. 3  is discharged as the lowermost sheet. Thereafter, separation can be conventionally effected and does not cause any difficulties. 
       FIG. 3a  schematically illustrates a top view of a two-section device of the invention.  FIG. 3b  shows a three-section device of the invention; and,  FIG. 3c  shows four sections of juxtaposed units  10  of the type shown in FIG.  1 .  FIG. 3d  schematically illustrates that feeding units  11  can service a series of juxtaposed units  10  from both sides by merely respectively changing the orientation of the diagonal guide slots  33 . 
     While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention. For more-secure guidance and rerouting of the sheets to be handled in the guide slot  33  and in the outlet slot  49 , for example, it is possible to provide more than two conveyor belts such as  42  and  43  accompanied by associated rows of roll elements  39 .