Abstract:
A method and apparatus for producing a digitally printed product that includes at least one section of sequentially printed sheets folded approximately in the center. The sequentially printed sheets are conveyed one after another on a conveying device and folded inside a folding apparatus to form a first fold. The folded sheets are gathered in a gathering station to form a section which is fed to a work station where the section is folded approximately in the center to form a second fold.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims the priority of European Patent Application No. 05405540.5, filed on Sep. 14, 2005, the subject matter of which is incorporated herein by reference, along with all other patents and patent applications, U.S. or foreign, which are referenced herein.  
       BACKGROUND OF THE INVENTION  
       [0002]     The invention relates to a method for producing digitally printed products, comprising at least one newspaper section composed of sequentially printed sheets, which are folded in the center. The invention furthermore relates to an arrangement for realizing said method.  
         [0003]     Newspaper production methods are not new. Traditionally, newspapers were produced with the offset or gravure printing technique by imprinting paper webs or large sheets on both sides, which are then combined to form a newspaper section. These days, newspapers are produced with the aid of digital printers, which allow the sequential printing of individual sheet sections in such a way that a complete newspaper is obtained at the end. Different newspapers can thus be printed in an optional sequence, and it is furthermore possible to print newspapers one after another in the so-called broadsheet format and the tabloid format.  
         [0004]     European Patent Application Publication EP 1 209 000 A discloses a method for which individual flat sheets are gathered and are then folded while positioned loosely one on top of the other. However, the aligning and folding of such sheets of freshly printed newspaper is very difficult in practical operations.  
       SUMMARY OF THE INVENTION  
       [0005]     It is an object of the present invention to develop a method of the aforementioned type which avoids this difficulty.  
         [0006]     The above and other objects are accomplished according to the invention by the provision of a method for producing a digitally printed product that includes at least one section (also referred to as stack or bundle) of sequentially printed sheets folded approximately in the center. According to one exemplary embodiment, the method comprises: folding the sequentially printed sheets, which are conveyed one after another on a conveying device, inside a folding apparatus to form a first fold; gathering the folded sheets in a gathering station to form a section; and feeding the section to a work station and folding the section in the work station approximately in the center to form a second fold.  
         [0007]     Thus, the method according to the invention includes individually folding the sequentially printed sheets in a folding apparatus, gathering and compiling the folded sheets in a gathering station into a section, and supplying this section to a work station where it is folded approximately in the center. With this method, the folded sheets can be aligned while the newspaper section is formed, which is possible even with large sheets of newly printed newspaper. The foregoing method is suitable for producing extremely thick newspapers.  
         [0008]     According to one exemplary embodiment of the invention, a continuous paper web is printed on and is then cut, preferably with a crosscutter, so that sheets are formed and are preferably ordered sequentially.  
         [0009]     Prior to the gathering operation, the separated sheets can be folded in a folding apparatus, preferably a continuous folding apparatus.  
         [0010]     A particularly secure and reliable gathering of the folded sheets is possible if the sheets are gathered on a non-moving gathering chain. For this, the sheets are preferably pushed against an adjustable end stop and are gathered until a complete newspaper section is obtained.  
         [0011]     According to another exemplary embodiment of the invention, the gathering station is provided with an extendable sword for holding back the sheets just long enough to allow a completely gathered newspaper section to be conveyed further, thus making possible a continuous production.  
         [0012]     A further exemplary embodiment of the invention provides that the gathered newspaper section is processed further while arranged at an angle, thereby permitting an advantageous alignment of the newspaper section against end stops due to the forces of gravity.  
         [0013]     Yet another exemplary embodiment of the invention is provided with a first work station, which comprises at least one trimming knife and/or a stitching unit for producing a tabloid. To produce a tabloid, the newspaper section is preferably trimmed and simultaneously stitched along the fold in this first work station. Newspaper sections of very different thicknesses can thus be stitched without requiring a complicated electric-motor adjustment by combining the press crosshead and the trimming device with the operation of the bending units for the stitching apparatus. In this way, tabloids with formats trimmed to different dimensions can thus be produced with a quick change in the trimming length and by varying the trimming in this first work station.  
         [0014]     According to another exemplary embodiment of the invention, a second work station is provided for folding one or several newspaper sections. When producing a newspaper in the broadsheet format, this fold is the second fold, whereas it is the first fold for producing a tabloid.  
         [0015]     According to yet another exemplary embodiment of the invention, a complete newspaper is assembled from several newspaper sections that are gathered, for example, inside circulating pockets or in a star-shaped delivery device.  
         [0016]     Additional advantageous features follow from the patent claims, the description below, as well as the drawings.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]     These and other features and advantages of the invention will be further understood from the following detailed description of the exemplary embodiments with reference to the accompanying drawings. The drawings show:  
         [0018]      FIG. 1 : A schematic side view of the apparatus according to an exemplary embodiment of the invention;  
         [0019]      FIG. 2 : A schematic side view of a back region of the apparatus according an exemplary embodiment of the invention;  
         [0020]      FIG. 3 : An enlarged view of a portion of the apparatus as depicted in  FIG. 1 ;  
         [0021]      FIG. 4 : An enlarged view of a different portion of the apparatus as depicted in  FIG. 1 ;  
         [0022]      FIG. 5 : An enlarged view of a portion of the back region of the apparatus as depicted in  FIG. 2 ;  
         [0023]      FIG. 6 : A different view of the apparatus as depicted in  FIG. 5 ;  
         [0024]      FIG. 7 : An enlarged view of a portion of the apparatus as depicted in  FIG. 2 ;  
         [0025]      FIG. 8 : A different view of the apparatus as depicted in  FIG. 7 ;  
         [0026]      FIG. 9 : An enlarged view of another portion of the apparatus as depicted in  FIG. 2 ; and  
         [0027]      FIG. 10 : A different view of the apparatus as depicted in  FIG. 9 . 
     
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
       [0028]     A region of the arrangement according to the invention is shown in  FIG. 1 , which is adjoined directly by a back region shown in  FIG. 2 . The arrangement is used for producing newspapers Z ( FIG. 2 ), composed of one or several newspaper sections B ( FIG. 1 ). The newspaper Z can be a newspaper in the so-called broadsheet format, meaning a standard large-format newspaper. The newspaper Z or at least one newspaper section B, however, can also be a newspaper in tabloid format. Newspapers in tabloid format have a smaller format and are stitched.  
         [0029]     According to  FIG. 1 , the arrangement comprises a digital printer D, for example a laser printer or ink-jet printer. This digital printer D is used to print on both sides of a continuous paper web  1 , in a manner that is known in the art. As a result, parts of a sheet can be successively printed on, so that a complete newspaper Z is obtained. For producing newspapers in the broadsheet format, the two sides of the paper web  1  are thus imprinted while upright, side-by-side. For newspapers in the tabloid format, two pages per section are printed one above the other and two pages are printed while positioned side-by-side. The digital printer D permits a rapid change between the two aforementioned formats, so that the newspaper Z can be composed of sections B in the broadsheet format and in the tabloid format.  
         [0030]     The paper web  1  is conveyed in the region of a first conveying segment F 1  with the aid of delivery rollers  2  and with a predetermined speed and tension. Behind these delivery rollers  2 , the continuous paper web  1  is supplied to a crosscutter  3  which separates the continuous paper web  1  into sheets  4 . The crosscutter  3  comprises a rotating blade  49  and a fixed blade  50 , and can be a crosscutter that is known in the art. The sheets  4  are also full-sized sheets. To produce a section B in the broadsheet format, a sheet  4  of this type contains four pages, while it contains eight pages for a tabloid format. The cutting length for the sheet  4  is controlled by crosscutter  3 . The cutting length of sheet  4  is a function the speed of the crosscutter  3 .  
         [0031]     The crosscutter  3  is operated by means of a drive, not shown herein, and is controlled by the printer D so that the sheets  4  are separated according to sequence. Essentially simultaneous with the separation operation, each sheet  4  that is cut off is also accelerated with the aid of a tear-off cylinder  5  or a different suitable device and is transported further with the aid of vacuum belts  6 . As a result of this acceleration, a fixed separation of the forward-moving sheets  4  is achieved. The tear-off cylinder  5  has a higher circumferential speed (measured in mm/cycle) than the speed at which the sheets  4  are traveling on the conveyor, so that a predetermined gap  7  is created between respectively two sheets  4 .  
         [0032]     A centering device  8  is provided in the region of the first conveying segment F 1 , by which the sheets  4  can be aligned precisely on the side and can be transported further with the same timing and with the aid of belts  9 , for example toothed belts. To ensure a secure transport and the aforementioned alignment on the side, a plurality of balls  10  are provided in the region of belts  9 . Balls  10  are positioned in a band  52  and due to their inherent weight, push onto the sheets  4  and/or the belts  9  underneath.  
         [0033]     The sheets  4 , which are aligned and spaced-apart as explained above, are weakened in the center by means of scoring rollers  12  before being folded in a continuous folding apparatus  11 . In the process, the sheets  4  are guided by intake belts  13  so that the sheets  4  are subsequently folded precisely along the weakened line while moving through the continuous folding apparatus  11 . The intake belts  13  are somewhat slanted in a downward direction, relative to a horizontal line, as shown in  FIG. 1 . The same is true for the continuous folding apparatus  11 . Dashed lines in  FIG. 1  indicate two folded sheets  16  and  16 ′. The folding operation may be accomplished by using circulating profile belts  14  or other types of belts, wherein it is also conceivable to use a different type of folding apparatus. Examples of such folding operations are set forth in Swiss Patent CH 615 646 and or U.S. Pat. No.4,221,373.  
         [0034]     Upon leaving the continuous folding apparatus  11 , the sheets  16  and/or  16 ′ are pressed down respectively along the fold by vertical rollers  15 , which results in a more accurate and sharper fold.  
         [0035]     The continuous folding apparatus  11  is followed by a second conveying segment F 2 , provided with a gathering station S in which the sheets  16  and/or  16 ′ are gathered to form a complete newspaper section B and/or B′. In the embodiment illustrated in  FIG. 1 , gathering station S is located in an upstream location within second conveying segment F 2 . The second conveying segment F 2  comprises an endless gathering chain  17 , preferably an endless double chain which is known in the art. This chain comprises saddle-shaped elements  57 , as shown in  FIG. 4 , as well as uniformly spaced-apart carriers  24 . The gathering chain  17  is fitted around rollers  58  and is driven intermittently with a drive, not shown herein.  
         [0036]     The upper segment of the gathering chain  17  moves from the left to the right as shown with arrow  53  in  FIG. 4 .  FIG. 4  also shows that the gathering chain  17  is provided with an end stop  18 , which can be adjusted to a limited degree in the directions of double arrow  59  with the aid of a thread spindle  61  that is positioned to rotate in a bearing  62  and is driven, for example, by motor  60 . The end stop  18  is positioned to be displaceable along guide rods  63 , wherein an adjustment to the format of the folded sheets  16  and/or  16 ′ is possible by displacing the end stop  18 .  FIGS. 1 and 4  show a sheet  16  having a smaller format that a sheet  16 ′. A control unit, not shown herein, is used for the adjustment control. To reduce the impact between the sheets  16  and/or  16 ′ and the end stop  18 , the above-mentioned pressing rollers  15  ( FIG. 1 ) can be operated with the aid of a servo motor that is not shown herein, such that the speed of sheets  16  and/or  16 ′ is slowed just prior to leaving the pressing rollers  15 .  
         [0037]     The sheets  16  and/or  16 ′ are gathered while the gathering chain  17  is standing still. The individual sheets can be gathered while positioned on top of each other or while inserted into each other. Once the newspaper section B and/or B′ is fully assembled, a sword  20  is extended in the conveying direction to the position shown in  FIG. 4 , causing the following sheets  16  and/or  16 ′ to drop onto this separating sword  20  and be held back. At the same time, the newspaper section B and/or B′ formed on the gathering chain  17  is conveyed from the left to the right as shown in  FIG. 4 . The newspaper section B and/or B′ is conveyed just far enough to reach the partition  22  shown in  FIG. 1 , whereupon the separating sword  20  is pulled back again, causing the sheets  16  and/or  16 ′ that have collected on the separating sword  20  to fall onto the gathering chain  17 , which is again standing still. The additional sheets  16  and/or  16 ′ subsequently drop once more directly onto the stopped gathering chain  17  and/or onto the sheets  16  and/or  16 ′ already positioned thereon, until an additional newspaper section B and/or B′ is completely assembled. The dual gathering chain  17  is then started once more and the separating sword extended.  
         [0038]     The newspaper sections B and/or B′ are transported on the gathering chain  17  with the aid of the aforementioned carriers  24  against which the sections B and/or B′ come to rest. The separating sword  20  moves inside a linear guide  25  and is moved back and forth substantially in horizontal direction by a toothed belt  26 , driven with a servomotor  27 .  
         [0039]     At the end of the first conveying segment F 1 , the newspaper section B and/or B′ is supplied by a delivery device  28 , shown in greater detail in  FIG. 5 , to the following processing unit. In accordance with embodiments of the invention, the delivery device  28  acts as an inserting device. The delivery device  28  is provided with an ejection comb  29 , which can be moved substantially vertically in the directions of double arrow  64 , as shown in  FIG. 5 . The ejection comb lifts the newspaper section B and/or B′ from the gathering chain  17  and pushes it between a belt  65  and a roller  66 , which move the newspaper section B and/or B′ in upward direction, where it is redirected by a curved sheet metal guide  68  and is supplied to the belts  31  and round cords  70 . The ejection comb  29  is operated by means of a drive  54  and comprises a rod  56  that is guided on rolls  55  (See  FIG. 4 ). The roller  66  is positioned on a suspension  67 , which can be pivoted around an axis  19 , so that the roller  66  can be adapted to different thicknesses of the newspaper section B and/or B′, wherein the contact pressure can additionally be adjusted.  
         [0040]     The belts  31  and the cords  70  can be swiveled as shown in  FIG. 6  so that the section B and/or B′ can be oriented centrally for the further stitching and folding operation, as mentioned below. The belts  31  are driven with the aid of a drive shaft  69 , which acts via toothed belts  95  upon pivoting rollers  96  around which belts  31  are fitted. For the adaptation to different formats, a contact roller  71  can be displaced as shown with double arrow  97  ( FIG. 6 ). The cords  70  run on grooved rollers  87 . The drawing at the top of  FIG. 6  shows the section B and/or B′ prior to the orientation while the drawing at the bottom shows the section in the oriented position. However, other means that are known in the art can also be used for orienting the section B and/or B′. During the orienting, the section B and/or B′ moves downward at a slant, as shown in  FIG. 5 . Due to the fact that the section B and/or B′ is held by cords  70 , a horizontal transport would also be conceivable, which has the advantage of a lower structural height.  
         [0041]     The centrally oriented section B and/or B′ is then supplied to a first work station Al (see  FIGS. 2 and 7 ) where it slides under the force of gravity and aligns itself as a result of its inherent weight with its fold against a stop element  32 . The stop element  32  is operated, for example, with the aid of a pneumatic cylinder  76 . The work station A 1  shown in  FIG. 2  is positioned at an angle and, for drawing reasons, is shown upright in  FIG. 7 . As shown in  FIG. 2 , the transporting plane for the newspaper section B and/or B′ in the work station A 1  points downward at an angle. Relative to a horizontal line, this angle is more than 10°, preferably more than 20°, and especially preferred approximately 30°. Owing to this angle and its inherent weight, the section B and/or B′ can align itself along the folding edge, as explained below.  
         [0042]     The first work station A 1  is used for trimming and/or stitching the newspaper section B if this section is intended for producing a tabloid.  
         [0043]     The work station A 1  comprises a trimming device with a vertically moving knife  33  and a stationary counter knife  37 . According to  FIGS. 7 and 8 , the moving knife  33  is attached to a yoke  34 , in a manner known in the art, and is moved vertically by means of pull and guide rods  80 .  
         [0044]     The pull and guide rods  80  move along guide elements  35  and engage via a slide ring  98  in a crankshaft pin  36 .  
         [0045]     The two crankshaft pins  36  are attached to an eccentric cam  79  of a drive shaft  78 . The yoke  34  is driven intermittently and is idle while in the upper position shown in  FIGS. 6 and 7 . The section B is trimmed, as mentioned in the above, along its section fold  30 , wherein the knife  33  and the counter knife  37  in this case function in the manner of a pair of scissors.  
         [0046]     A crosshead  38  of a press is arranged on the yoke  34 , which pushes under the effect of springs  75  onto the section B prior to the cutting operation, so that a clean cut can be made. Following the trimming operation, the press crosshead  38 , which is attached to guide rods  74 , is again moved upward and into the idle position shown in  FIGS. 7 and 8 . In place of a single newspaper section B, several folded newspaper sections can also be gathered, trimmed, and then stitched as explained in the following.  
         [0047]     The newspaper section B can be stitched with a stitching unit H provided with two stitching heads  41  and two bending units  39 . As can be seen, the stitching heads  41  are arranged below the conveying segment F 2 , which convey section B, and the bending units  39  are arranged above conveying segment F 2 . One stitching head  41  operates jointly with a bending unit  39 , which can be accomplished in a manner known in the art. Wire staples, which are known in the art and are not shown herein, are used for the stitching in this case. The bending units  39  are attached to a support  73  that is connected to the press crosshead  38  and is moved in vertical direction along with this crosshead. When the press crosshead  38  is lowered, the bending units  39  are lowered at the same time and are pressed against the section B. As a result, the bending units  39  are automatically adjusted to the thickness of the newspaper section B and are thus always in the optimum position for the stitching operation. The bending units  39  are provided with standard bending wings for closing the wire staples, which are not shown herein. These bending wings are operated with the aid of a pneumatic cylinder  40 .  
         [0048]     The stitching heads  41 , which are positioned below and operate jointly with the bending units  39  as mentioned in the above, are driven separately from the knife  33  by a motor  77 . Each stitching head  41  is provided with connecting members  99 , which are activated by a crankshaft pin  100 . The interaction of the stitching head  41  with the connecting members  99  an be accomplished in a manner known to one of skill in the art. The press crosshead  38  and the knife  33  preferably have a considerably higher lift than would be necessary for trimming the newspaper section B. As a result, even a newspaper section B that is not pressed down optimally can move without problem underneath the bending units  39  and the press crosshead  38 , as well as the knife  33 , and can come to rest and align itself against the stop element  32 .  
         [0049]     As previously mentioned, only newspaper sections B for producing tabloids are trimmed and stitched in the first work station Al. If the newspaper section B is used to produce a newspaper Z in the broadsheet format, this newspaper section B is neither trimmed nor stitched, but only comes to rest against the stop element  32 , wherein the knife  33 , the press crosshead  38 , and the bending units  39  are immovable in the upper position, shown in  FIGS. 7 and 8 .  
         [0050]     Following the stitching and trimming of the section B, insofar as it takes place, the stop element  32  is lowered by activating a pneumatic cylinder  36  and the newspaper section B slides as a result of its inherent weight down the above-mentioned inclined path, shown in  FIG. 2 , by way of a ramp  42  and into the second work station A 2  with folding apparatus  43 , shown in  FIGS. 9 and 10 . The section B continues to slide until it reaches an end stop  45  ( FIG. 9 ) that is arranged above two press-on rollers  46 . When sliding into the second work station A 2 , the newspaper section B is centered on the side, relative to the two press-on rollers  46 , by the sheet metal guide  89  shown in  FIG. 10 . The two press-on rollers  46  operate jointly with a folding knife  81 , which is positioned on a vertical guide rod  84 , such that it can move vertically up and down. A crankshaft  83 , controlled by a drive  82 , is used to control the vertical movement of the folding knife  81 . The folding knife  81  acts upon the center of the newspaper section B to push the section between press-on rollers  46  that move toward each other. These press-on rollers  46  are each positioned on a two-arm lever  90 , as shown in  FIG. 10 , and are pressed against each other with the aid of a spring  91 . The newspaper section B is thus folded in the center with the aid of the two press-on rollers  46  and/or is provided with a fold. The force of the spring  91  and thus also the press-on force of the press-on rollers  46  can be adjusted with an adjustment device  92 , which permits the adaptation to differently thick newspaper sections.  
         [0051]     Several newspaper sections B and/or B′ can also be gathered above the two press-on rollers  46  in place of a single newspaper section B and/or B′, and these can subsequently be folded jointly with the aid of the folding sword  44 . For producing a newspaper in the broadsheet format with a section B and/or B′, the fold is the second fold which extends at a right angle to the above-mentioned first fold. For a tabloid, on the other hand, only a single fold is formed along the staples in the center.  
         [0052]     The folded newspaper section B is moved downward through the moving press-on rollers  46  and is supplied via a star-shaped delivery  47  to a delivery belt  48 .  FIG. 10  shows that the star-shaped delivery  47  is provided with a drum  93 , having several metal sheets  94  attached thereto, which are provided with pockets  101  for accommodating at least one newspaper section B and/or B′. The newspapers Z are transported further on this delivery belt  48 , for example in the form of an overlapping stream. The star-shaped delivery  47 , or a different delivery device, can be embodied so that several newspaper sections B and/or B′ are combined, for example inserted into each other, wherein a pocket  101  is used for the insertion. To accomplish the insertion, a first section B and/or B′ is positioned open-faced and pointing upward inside pocket  101 . Second section B and/or B′ can then be inserted from above into the first section. By this process, more than two sheets B and/or B′ can also be fitted into each other to produce very thick newspapers Z. Therefore, newspapers Z according to  FIG. 10  can comprise several newspaper sections B. A newspaper Z can also comprise one or several sections B in the broadsheet format and one or several sections B in the tabloid format, meaning extremely thick newspapers Z can thus be produced. The trimmed tabloids can have different dimensions and/or formats, which is also true for the newspaper sections B in broadsheet format.  
         [0053]     It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.