Abstract:
An apparatus positions sheets preferably moving in a combination folding machine and defines a trailing edge range. A trailing edge of the sheet is to be positioned in a transport direction, depending on the dimensions of the sheet. The apparatus has positioning devices, by which the trailing edge can be positioned. The positioning devices are fixed to a carrier, and also a carrier actuating device is provided, by which the carrier can be moved by a predefined actuating travel in the transport direction of the sheets, so that the trailing edge is positioned within a trailing edge positioning range. The positioning devices are fixed to the carrier such that the respectively different trailing edge positioning ranges of the individual positioning devices in total cover the entire trailing edge range but each respective trailing edge positioning range is shorter in the transport direction than the trailing edge range.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims priority, under 35 U.S.C. §119(e), of provisional application No. 60/667,103, filed Mar. 31, 2005; the application also claims priority, under 35 U.S.C. §119, of German patent application No. 10 2005 015 095.0, filed Apr. 1, 2005; the prior applications are herewith incorporated by reference in their entirety. 

   BACKGROUND OF THE INVENTION 
   Field of the Invention 
   The invention relates to an apparatus for positioning a trailing edge of sheet-like objects preferably moved in a combination folding machine. The apparatus has a positioning device by which the trailing edge of a sheet can be positioned, the positioning device being fixed to a carrier. A carrier actuating device is provided, by which the carrier can be moved by a predefined actuating travel in a transport direction of the sheets, so that the trailing edge of the sheet can be positioned within a trailing edge positioning range. 
   In combined pocket/blade folding machines, what are known as combination folding machines, the parallel folds are folded in a first folding station on the pocket folding principle, while the following cross folds are carried out with a folding blade operating vertically. For this purpose, following the parallel fold outlet, the folded sheets are transported without slippage to a cross folding station by transport belts. In order to ensure actually slippage-free transport, the transported flat goods must be held down and pressed vertically onto the transport belt. In order to produce the vertical contact force required for this, both loading balls and guide rollers are used. Loading ball systems of this type are known, for example from German Utility Model DE 84 06 391. In recent times, however, the use of guide rollers, which are described in German Utility Model DE 93 04 281, for example, has become more widespread. As compared with the loading ball system, these have particular advantages which relate, for example, in the fact that track-accurate sheet guidance can be achieved with guide rollers. In addition, the sheet can be folded without any weight loading. Furthermore, when guide rollers are used, it is possible to prevent the sheet springing back off the stops. 
   In order to prevent the sheet springing back off the stops, brushes or a brush strip are also placed on the folded sheet trailing edge for the purpose of the final positional fixing of the folded sheet. However, the brush strip, which brakes the folded sheet top side, is disadvantageous in particular for folded sheets having a low grammage, since symmetrical contact and therefore uniform braking are possible only with difficulty. In addition, the setting and positioning of the brushes or ball strips is time-consuming. 
   A precondition for the aforementioned advantages of the guide rollers is that the guide roller located closest to the cross fold stop is positioned exactly, which therefore results in that the sheet lies “free” between the leading edge stop and the guide roller. In order to ensure this, the guide roller must be positioned in such a way that the roller is just still rotating and is neither on the sheet trailing edge nor directly on the folded sheet. An apparatus of this type is known from German Utility Model specification DE 299 047 57. In this, an apparatus for holding down and loading moving sheet-like objects is proposed in which one or more guide rollers are provided in order to hold down the objects. For fully accurate positioning of the guide rollers, at least one of these guide rollers is equipped with a marking. 
   In the aforementioned folding machines, to some extent a plurality of blade folding units are also disposed one after another. When the sheets are aligned with leading edge and trailing edge stops in the first blade folding unit, the folding sheet is aligned longitudinally and centrally with respect to the following blade folding unit. In the event of a change in the format of the sheets, the leading stop and the trailing edge stop must also be moved in accordance with the new format. The size of the sheet upstream of the first blade folding unit depends on the size of the unfolded sheet and also on the manner in which the sheet has already been folded until it reaches the first blade folding unit. Because of the longitudinally central alignment, the actuating travel to be covered is divided uniformly between the adjustment of the leading edge stop and the trailing edge stop. For instance, the deviations of the format of the sheet upstream of the first blade folding unit are 48 cm. In the above-mentioned case, an actuating travel of up to 24 cm would therefore be necessary. 
   The drawback with the generic apparatus from the prior art is precisely this long actuating travel which such an apparatus has in the sheet running direction, since the actuating travel must be kept free. As a result, a sheet would not be guided over a correspondingly great distance, which can have a detrimental effect on the folding result, in particular for small sheets. 
   SUMMARY OF THE INVENTION 
   It is accordingly an object of the invention to provide an apparatus for positioning a trailing edge of sheet-like objects which overcomes the above-mentioned disadvantages of the prior art devices of this general type. 
   With the foregoing and other objects in view there is provided, in accordance with the invention an apparatus for positioning sheets. The apparatus has a trailing edge range, in which a trailing edge of a sheet being positioned in a transport direction, depends on dimensions of the sheet, a carrier, and a plurality of positioning devices for positioning the trailing edge of the sheet. The positioning devices are fixed to the carrier such that respectively different trailing edge positioning ranges of individual ones of the positioning devices in total cover entirely the trailing edge range but each of the respectively different trailing edge positioning ranges is shorter in the transport direction than the trailing edge range. A carrier actuating device is provided for moving the carrier by a predefined actuating travel in the transport direction of the sheets, so that the trailing edge of the sheet can be positioned within one of the respectively different trailing edge positioning ranges. 
   Now, from the prior art it is known that the trailing edge range, as it is known, that is to say the range over which the trailing edge of a sheet to be folded could lie on account of the format of the sheet to be processed or on account of preceding operations in order still to be able to be processed by the folding machine, must be smaller than the trailing edge positioning range. In this case, the trailing edge positioning range defines that region in which a positioning device can perform positioning. If the positioning device is fixed, then the trailing edge positioning range has no extent; if the positioning device can be adjusted along an actuating travel, then the limits of this adjustability specify the trailing edge positioning range precisely, since outside this trailing edge positioning range no trailing edge positioning by the positioning device is possible. However, if the trailing edge region were not covered by the trailing edge positioning range, some of the sheets could not undergo positioning of the trailing edge and would therefore not strike the leading edge stop properly. 
   Accordingly, the invention is based on the coverage of the trailing edge range by a plurality of trailing edge positioning ranges being achieved. Since the trailing edge positioning range is not greater than the actuating travel, a shortening of the actuating travel can be achieved by this measure. As a result, there remains space in which other elements, for example hold-downs, can be accommodated, so that improved guidance of the sheets on the way to the leading edge stop can be ensured. 
   In an advantageous development of the apparatus according to the invention, the trailing edge position ranges of the individual positioning devices do not overlap. Therefore the trailing edge positioning ranges adjoin one another directly and without gaps in the transport direction in order to cover the trailing edge range completely. However, this does not mean that the actuating travel of the carrier likewise has the same length of the individual trailing edge position ranges of the individual positioning devices; instead, the actuating travel in the transport direction of the carrier is advantageously somewhat longer than the length of the individual trailing edge positioning ranges of the individual positioning devices. Dispensing with overlapping the trailing edge positioning ranges makes it easier to control the drive of the carrier, since each possible trailing edge position is assigned one and only one trailing edge positioning range. On the other hand, by the somewhat longer actuating travel, it is ensured with adequate certainty that every point in the respective trailing edge positioning range can also actually be selected. 
   In a particularly advantageous refinement of the apparatus according to the invention, the positioning devices are guide rollers that are under the action of spring forces. Guide rollers of this type also already have proven to be worthwhile in comparable applications. 
   In an advantageous development of this embodiment, the guide rollers are assigned a back-pressure device, for example a common belt or individual backing rollers. 
   In an advantageous development of the apparatus according to the invention, an activation device is assigned to the positioning devices, the activation device is configured in such a way that the positioning devices can be moved thereby into an active or passive operating position. In the passive operating position, the positioning devices are not in contact with the sheet. Typically, all those positioning devices which are located above the sheet at the folding time are in a passive operating position, in order not to hinder the folding by friction or to leave behind possible markings on the sheet. In the active operating position, the positioning devices interacts with the back-pressure device and can fulfill two functions. The first is the positioning of the trailing edge, in that the positioning devices are located precisely at the point at which the trailing edge is intended to come to lie. The second function is holding down the sheet on the way to the leading-edge stop. This function is fulfilled by all positioning devices which are disposed upstream of the positioning devices that perform the positioning of the trailing edge. 
   In a particularly advantageous refinement of this embodiment, the activation device is configured in such a way that the operating position of all the positioning devices can be adjusted by a common pulling device. In this case, the pulling device is, for example, a toothed belt or an adjustable actuating strip. Alternatively, however, it is also conceivable to assign each positioning device its own activation device, for example small actuating motors with appropriate control. 
   In a particularly advantageous refinement of this embodiment, the activation device is configured in such a way that, following the movement of the positioning devices disposed after a first positioning device in the transport direction into an active operating position, all the positioning devices disposed upstream are in an active operating position. 
   In a further particularly advantageous refinement of this embodiment, the activation device is configured in such a way that, following the movement of positioning devices disposed after the first positioning device in the transport direction into a passive operating position, all the positioning devices disposed downstream are in a passive operating position. 
   Other features which are considered as characteristic for the invention are set forth in the appended claims. 
   Although the invention is illustrated and described herein as embodied in an apparatus for positioning a trailing edge of sheet-like objects, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
   The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagrammatic, side-eleveational view of essential parts of an apparatus according to the invention with an active positioning device; 
       FIG. 2  is a diagrammatic, perspective view of the apparatus with a leading edge stop in the case of the largest possible sheet; 
       FIG. 3  is a diagrammatic, side-elevational view of the essential parts of the apparatus according to the invention with five active positioning devices; 
       FIG. 4  is a diagrammatic, perspective view of the apparatus with the leading edge stop in the case of the smallest possible sheet; 
       FIG. 5  is a diagrammatic, side-elevational view of the essential parts of a further apparatus according to the invention with an active positioning device; 
       FIG. 6  is a diagrammatic, perspective view of the further apparatus according to the invention with the leading edge stop in the case of the largest possible sheet; 
       FIG. 7  is a diagrammatic, side-elevational view of the essential parts of the further apparatus according to the invention with five active positioning device; 
       FIG. 8  is a diagrammatic, perspective view of the further apparatus according to the invention with the leading edge stop in the case of the smallest possible sheet; 
       FIG. 9  is a diagrammatic, side-elevational view of the further apparatus according to the invention with a continuous back-pressure belt. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring now to the figures of the drawing in detail and first, particularly, to  FIG. 1  thereof, there is shown parts of an embodiment of an apparatus  100  according to the invention. In the figures, elements such as drives, cams, housings, controllers and so on known to those skilled in the art are shown only in highly simplified form if they are at the discretion of those skilled in the art. 
   The embodiment shown of the apparatus  100  according to the invention is part of a combination folding machine and is disposed upstream of a first blade folding unit there. Combination folding machines and blade folding units are known to those skilled in the art in large numbers from the prior art. In such a combination folding machine, the parallel folds are folded in a first folding station on the pocket folding principle, while the subsequent cross folds are carried out with a folding blade operating vertically. To this end, following an outlet from the parallel fold, the folded sheets  1 ,  2  are transported without slippage to a cross folding station by non-illustrated transport belts. In order to ensure actually slippage-free transport, the transported flat goods must be held down and pressed vertically onto the transport belt. 
   During alignment of the sheets  1 ,  2  with leading edge and trailing edge stops in the first blade folding unit, the folded sheet is aligned longitudinally and centrally with respect to the following blade folding unit. In this case, a trailing edge HK of the sheet  1 ,  2  can come to lie in a trailing edge range HKB, depending on the size of the sheet  1 ,  2 . The trailing edge range HKB is limited on one side by the greatest extent of the sheet  1 ,  2  in the transport direction, which is identified by arrow bearing the designation B, which the folding machine can still process and is limited on the other side by the smallest extent of the sheet  1 ,  2  in the transport direction B which can still be processed by the folding machine. An extent L 1 , L 2  of the sheet  1 ,  2  in the transport direction B in this case depends both on the unfolded dimensions of the sheet  1 ,  2  and also on possible preceding operations in the pocket folding units. Here, the trailing edge range corresponds exactly to half the difference between the greatest possible length L 1  ( FIG. 2 ) of the largest possible sheet  1  and the smallest possible length L 2  ( FIG. 4 ) of the smallest possible sheet  2 . This is because the folded sheet is folded longitudinally and centrally around a center line ML of the sheet  1 ,  2 , see  FIG. 2  and  FIG. 4 , and the folding blade is not moved for this purpose. Half of the distance is apportioned to a displacement of a leading edge stop  90 . Otherwise, the type of adjustment of the leading edge stop  90  by an actuating travel SWA is not essential to the invention. 
   As can be seen in  FIG. 1  to  FIG. 4 , a plurality of positioning devices  10 ,  20 ,  30 ,  40 ,  50  are disposed along the transport path B of the sheet. The positioning devices  10 ,  20 ,  30 ,  40 ,  50  are in particular guide rollers  10 ,  20 ,  30 ,  40 ,  50 . Each of the guide rollers  10 ,  20 ,  30 ,  40 ,  50  is assigned a back-pressure roller  70 . In a particularly advantageous embodiment that is not shown, the guide rollers  10 ,  20 ,  30 ,  40 ,  50  are assigned a transport belt as a common back-pressure device. A transport belt of this type is advantageously assisted by appropriate back-pressure rollers  70  opposite the guide rollers  10 ,  20 ,  30 ,  40 ,  50 , but it is also conceivable that the transport belt merely runs in a suitable groove. 
   The guide rollers  10 ,  20 ,  30 ,  40 ,  50  are fitted to a common carrier  80 . The carrier  80  can be displaced along the transport path by an actuating travel SWT by a drive  82 . The displacement of the carrier  80  is advantageously carried out automatically in interaction with information with regard to the intended position of the trailing edge HK of the sheet  1 ,  2 . This information is interchanged with a controller  61 , with which at least the two drives  62 ,  82  interact and exchange data with one another. By the actuating travel of the carrier SWT, each individual positioning element  10 ,  20 ,  30 ,  40 ,  50  can be displaced within a trailing edge positioning range HKPB 1 , HKPB 2 , HKPB 3 , HKPB 4 , HKPB 5 . In this case, the length of the actuating travel of the carrier SWT is such that it exceeds the length of each individual trailing edge positioning range HKPB 1 , HKPB 2 , HKPB 3 , HKPB 4 , HKPB 5  somewhat. The individual trailing edge positioning ranges HKPB 1 , HKPB 2 , HKPB 3 , HKPB 4 , HKPB 5  do not overlap but adjoin one another directly. In total, the trailing edge positioning ranges HKPB 1 , HKPB 2 , HKPB 3 , HKPB 4 , HKPB 5  project somewhat beyond the trailing edge range HKB. Partial mutual overlapping of the trailing edge positioning ranges HKPB 1 , HKPB 2 , HKPB 3 , HKPB 4 , HKPB 5  is also conceivable. The length of a trailing edge positioning range HKPB 1 , HKPB 2 , HKPB 3 , HKPB 4 , HKPB 5  corresponds precisely to a distance D between two adjacent guide rollers  10 ,  20 ,  30 ,  40 ,  50  from one another. However, it is also conceivable to configure the guide rollers  10 ,  20 ,  30 ,  40 ,  50  not to be equidistant; however the equidistant embodiment of the guide rollers  10 ,  20 ,  30 ,  40 ,  50  is more practical. The trailing edge range HKB is ultimately subdivided into 5 trailing edge positioning ranges HKPB 1 , HKPB 2 , HKPB 3 , HKPB 4 , HKPB 5  in this exemplary embodiment, and the necessary actuating travel of the carrier STW is reduced to approximately one fifth. 
   The individual guide rollers  10 ,  20 ,  30 ,  40 ,  50  can rotate freely in the clockwise direction about a roller axis  12 ,  22 ,  32 ,  42 ,  52  in the present embodiment. The guide rollers  10 ,  20 ,  30 ,  40 ,  50  are sprung against the back-pressure rollers  70 . To this end, all the guide rollers  10 ,  20 ,  30 ,  40 ,  50  have a swinging arm  14 ,  24 ,  34 ,  44 ,  54 , by which they can be pivoted about a corresponding pivot axis  16 ,  26 ,  36 ,  46 ,  56 . In this case, the first guide roller  10  in the transport direction is always in an active operating position and therefore interacts continuously with the corresponding back-pressure roller  70 . The first guide roller  10  pivots about the pivot axis  16  when it is lifted off the back-pressure roller  70  counter to the spring force by the thickness of an incoming sheet  1 ,  2 . 
   All the guide rollers  20 ,  30 ,  40 ,  50  following downstream are connected to an activation device  60 , a toothed belt  60  which is wrapped around a corresponding gear wheel  28 ,  38 ,  48 ,  58  and is tensioned by tensioning rollers  63 ,  64 ,  65  which are disposed between the guide rollers  10 ,  20 ,  30 ,  40 ,  50 . In addition, the activation device contains the drive  62 , which effects a movement of the toothed belt  60  and therefore a rotation of the gear wheels  28 ,  38 ,  48 ,  58 . The respective gear wheel  28 ,  38 ,  48 ,  58  in each case has a dog  29 ,  39 ,  49 ,  59 , which is in contact with the respective swinging arm  24 ,  34 ,  44 ,  54  of the appropriate guide roller  20 ,  30 ,  40 ,  50  when the guide roller is in a passive operating position. In this case, the position of the dog  29 ,  39 ,  49 ,  59  when the toothed belt  60  is incorporated is displaced by a few degrees of angle in the clockwise direction downstream from guide roller  20 ,  30 ,  40 ,  50  to guide roller  20 ,  30 ,  40 ,  50 . The result, as shown in  FIG. 1  and  FIG. 2 , is that the guide roller  20 ,  30 ,  40 ,  50  is moved further and further away from the corresponding back-pressure device  70  in the transport direction B. This has the effect that, during the movement of the toothed belt  60  in the transport direction B, first the second transport roller  20 , then the third transport roller  30 , then the fourth transport roller  40  and lastly also the fifth transport roller  50  is lowered. In the process, the dogs  29 ,  39 ,  49  in the preceding guide rollers  20 ,  30 ,  40  are moved further and further away from the contact point with the swinging arm  24 ,  34 ,  44  as soon as the interaction of the respective guide roller  20 ,  30 ,  40  with the associated back-pressure device  70  begins. This state is shown in  FIG. 3  and  FIG. 4 . 
   An alternative embodiment is illustrated in  FIGS. 5 to 8 . 
   The individual guide rollers  10 ,  20 ,  30 ,  40 ,  50  can rotate freely in the clockwise direction about the roller axis  12 ,  22 ,  32 ,  42 ,  52  in this embodiment. The guide rollers  10 ,  20 ,  30 ,  40 ,  50  are likewise sprung against the back-pressure rollers  70 . To this end, all the guide rollers  10 ,  20 ,  30 ,  40 ,  50  have the swinging arm  14 ,  24 ,  34 ,  44 ,  54 , by which they can be pivoted about the corresponding pivot axis  16 ,  26 ,  36 ,  46 ,  56 . In this case, the first guide roller  10  in the transport direction is always in an active operating position and therefore interacts continuously with the corresponding back-pressure roller  70 . The first guide roller  10  pivots about the pivot axis  16  when it is lifted off the back-pressure roller  70  counter to the spring force by the thickness of an incoming sheet  1 ,  2 . 
   The guide rollers  20 ,  30 ,  40 ,  50  following downstream have an adjusting surface  112  at their one end of the swinging arm  24 ,  34 ,  44 ,  54 . The adjusting surface  112  interacts with pins  111  which are fixed to an adjustable actuating strip  110 . The adjustable actuating strip  110  is connected to the drive  62 , which sets the strip moving linearly. The pins  111  are disposed on the strip  110  in such a way that they touch the adjusting surfaces  112  sequentially and therefore bring the rollers  20 ,  30 ,  40 ,  50  sequentially from a passive into an active operating position. 
   The result, as  FIGS. 5 and 6  show, is that the guide rollers  20 ,  30 ,  40 ,  50  are moved further and further away from the corresponding back-pressure device  70  in the transport direction B. This has the effect that, during the movement of the adjustable actuating strip  110  in the transport direction B, first the transport roller  20 , then the third transport roller  30 , then the fourth transport roller  40  and finally also the fifth transport roller  50  will then be lowered. In the process, the pins  111  in the preceding guide rollers  20 ,  30 ,  40  are moved further and further away from the adjusting surface  112  of the swinging arms  24 ,  34 ,  44  as soon as the interaction of the respective guide roller  20 ,  30 ,  40  with the associated back-pressure device  70  begins. This state is shown in  FIGS. 7 and 8 . 
   In a further embodiment, the back-pressure rollers  70  are configured as a continuous belt  113 , as illustrated in  FIG. 9 . 
   Then, if a change between two sheet sizes is carried out, it is first determined in which trailing edge positioning range HKPB 1 , HKPB 2 , HKPB 3 , HKPB 4 , HKPB 5  the trailing edge HK of the sheet  1 ,  2  falls. Then, the positioning devices  10 ,  20 ,  30 ,  40 ,  50  assigned to the trailing edge positioning range HKPB 1 , HKPB 2 , HKPB 3 , HKPB 4 , HKPB 5  is moved to the appropriate position within the available actuating travel of the carrier STW, and the leading edge stop  90  is likewise moved into the appropriate position. Then, if for example the trailing edge HK of a sheet  1 ,  2  falls into the trailing edge positioning region HKPB 3  of the guide roller  30 , then the third guide roller  30  would be positioned exactly at the location of the trailing edge HK of the sheet  1 ,  2 , the guide rollers  10 ,  20  located upstream would likewise be in an active operating position, in which they hold down the sheet for as long as possible on the way to the leading edge stop. The guide rollers  40 ,  50  located downstream would, on the other hand, be in a passive operating position, in which they do not hinder the folding of the sheet  1 ,  2 . 
   Such an apparatus according to the invention can be used in all blade folding or combination folding machines, in particular including in the second and third cross fold, but also in other apparatus in which the intention is to ensure the longest possible guidance of the products to be processed with, at the same time, a fast format change and high positioning accuracy.