EP2727869B1 - Device and method for folding printed sheets - Google Patents

Description

The invention relates to a device and a method for folding printed sheets according to the preamble of claim 1 or according to the preamble of claim 11.

For further processing of printed paper sheets, so-called printed sheets, which have two or more printed pages, these sheets are bent at least once on a prepared by perforation or creasing or on an unprepared fold line according to a predetermined folding scheme under pressure sharp edged, ie the format of the later Folded printed product. With reference to the feed direction of the printed sheets, both transverse and longitudinal folding devices are used, which can be arranged simply, repeatedly and also combined in a folding machine.
The folding takes place by means of a so-called pocket and / or Schwertfalzprinzips. Regardless of the type of device used and the corresponding method, the accuracy of each individual fold is decisive for the quality of the printed product to be produced.

From the DE3544495 A1 is a working according to the Schwertfalzprinzip folding device for Querfalzen known, in which in each case a sheet is fed by means of feed rollers in the feed direction on a folding table and there against a stop. The folding table has a recess formed transversely to the feed direction, over which a mechanically driven folding blade is arranged. Below the folding table two parallel to this aligned folding rollers are arranged in the region of the recess. As soon as the front edge of the sheet to be folded in the feed direction abuts against a stop projecting upwardly beyond the folding table, the lowering of the folding blade is triggered on the sheet located on the folding table. The folding blade presses against the folding line, ie against an imaginary straight line of the sheet to which it is to be folded, and thus guides the sheet through the recess of the folding table to the folding rollers. The signature is then picked up by the folding rollers and drawn into the fold gap formed between them, thereby bent over at the fold line and pressed. The thus folded sheet is then removed by means of the folding rollers down. There are also folding machines with a arranged below the folding table folding blade and arranged above the folding table folding rollers are known in which the folded sheet is removed each upward.

Regardless of its specific arrangement, such a mechanical folding blade requires very precise and elaborate geometric adjustments. Likewise, the length of the folding blade for the purpose of adaptation to the format of the sheet is variable constructable only with great effort. In addition, a mechanical folding blade requires a relatively large space and yet has poor accessibility. Due to the required high folding performance, the folding blade must be moved as quickly as possible and therefore applies to the printed sheet at a relatively high speed. In order not to get in contact with the folding rollers and to release the space on the folding table as quickly as possible for the supply of the next sheet, the folding blade must already in good time before reaching the folding rollers perform a previous lowering opposite movement. Therefore, the sheet to be folded is in an undefined motion just before being picked up by the folding rollers. The printed sheet can thus deviate from the intended trajectory and may not be detected by the folding rollers. Therefore, there is a permanent congestion driving sequentially supplied sheet. In addition, compared to their folding position shifted sheet can be folded only with greater technical effort to the intended fold line. Finally, the formation of so-called dog-ears, ie the turning over of the ends of the sheet at high speeds hardly manageable, because corresponding guide elements are only limited usable due to the space required by the mechanical sword. Accordingly, when using a mechanical sword, the risk of impairing the quality of the subsequent printed product may be reduced but not eliminated with a high technical outlay.

With a likewise known, suitable for high folding performance, rotating folding blade of the folding time can be hardly varied because of the inertia of the device.

The DE10238502 A1 discloses a method suitable for transverse or Längsfalzen each of a sheet and a device, wherein instead of a mechanical pneumatic sword, ie a compressed air device consisting of a tube with preferably downwardly directed outlet openings is used. The printing sheet is fed to this device in a guide plane and thereby provided in a folding position in which its intended fold line is located below the outlet openings of the compressed air device. At this moment receives the compressed air device via a control unit, a trigger pulse for a directed to the folding line of the sheet, strong compressed air blast, for example, a few hundred bar. As a result of the action of this compressed-air impact, the printed sheet is guided at its folding line into the folding gap located between the folding rollers. Since in this way an undefined trajectory of the sheet is excluded, the risk of deterioration of the quality of the subsequent printed product compared to a solution with a mechanical sword can be reduced.

Due to the arrangement and design of the compressed air device, however, this solution does not allow adaptation to different formats successively to folding sheet. Thus, for example, a print sheet following a small-scale print sheet would already be in the area of the compressed air device before the previous print sheet had been forwarded to the folding rollers. Consequently, the compressed air device would have to be replaced, which would be time consuming and costly. Alternatively, the spacing of successive sheets could be adjusted to the changing format. However, this would require higher transport speeds and thus entail process disadvantages.

If a transverse fold is also produced immediately before a longitudinal fold, a gap between the folded printed sheets, which corresponds to the length of the respective printed sheet, is produced by the transverse folding both in the case of mechanical and pneumatic swords. In a variable format, i. variable length of successively to be folded sheet, the relatively stable fold edge of the transverse fold can not be spent in an advantageous for transfer to the following machine defined fixed position, because the folded edge of a subsequent, shorter sheet are otherwise already in the rebate of the sword and thus the sole folding of the previous print sheet would be impossible. As a result, a complex, adjustable stop is required. In addition, both the lowered mechanical sword and the compressed air stream of the pneumatic sword directed from the compressed air device onto the printed product to be folded obstructs an immediate supply of the next printed sheet and thus a faster production.

Especially in the further processing of digital presses sequentially printed sheet with which printed sheets printed in the predetermined order of the finished printed product and are produced in relatively small quantities to a copy, it comes in comparison to conventional printing methods, such as offset printing, however very often to successive sheets of different format, which can be folded with the known from the prior art devices and methods only after replacement of the compressed air device or after an adjustment of the distance successive signature. In addition to the above-mentioned disadvantages of the pneumatic sword thus also an automation of the folding process is made difficult or impossible.

Finally, digital printing machines in which the print image is transferred directly from a computer to the press without the use of static printing forms nowadays print ever larger amounts of printing material per unit time, which is both the quality and the performance of the used for further processing Devices, such as the folding devices, much higher demands than before.

The object of the invention is therefore to provide a device and a method for folding sheets, which allow for high folding quality and performance, a simple and cost-effective adaptation to different formats of successive sheets and an automation of the folding process and therefore also for further processing of means Digital presses sequentially printed sheet are suitable.

The object is achieved by a device having the features of the characterizing part of claim 1 and by a method having the features of the characterizing part of claim 11. Advantageous embodiments are specified in the respective subclaims.

For this purpose, the compressed air device of the device according to the invention has at least two segments which each have at least one outlet opening provided with a cross-sectional area. Each segment is connected to the compressed air source and the control unit, has at least one control element and is designed separately controllable with compressed air.

As a result of the segmentation of the compressed air device, at least two regions of the device arranged side by side or one behind the other in the feed direction can advantageously be subjected to compressed air individually. Therefore, it is possible to supply only the segment or the segments with compressed air, which correspond to the format of the printed sheet provided. In the case of a small-format printed sheet, for example, only one segment or part of the segments can be supplied with compressed air, so that the compressed-air impact on the printed sheet provided takes place only from the outlet openings of this one segment or part of the segments. Likewise, within the device, at least two printed sheets provided in succession can advantageously be treated both identically and differently according to their format. at corresponding pressurization of at least one of the controls of at least one segment, the compressed air impact of at least one segment, multiple segments or the entire compressed air device can be dosed easily and quickly according to the format of the sheet provided in the respective folding position and both good folding quality over the entire spectrum for folding printed sheet also a high folding performance can be achieved.

According to the method according to the invention, the control unit triggers a blast of compressed air from the at least one outlet opening of at least one of the segments of the compressed air device onto the printed sheet provided. By applying at least one of the segments, the compressed air surge of the compressed air device can be easily and quickly metered according to the format of a sheet currently being folded provided in the folding position and both good folding quality and high folding performance can be achieved over the entire spectrum for folding printed sheets.

In addition, asymmetric printed sheets with different mass distribution, i. Sheet with different page numbers on both sides of an existing fold are transported by applying the appropriate segments evenly to the folding rollers. As a result, even such sheets can be transversely folded with good folding quality.

In addition, the device according to the invention for providing the printing sheet either has a first or second feeding direction substantially perpendicular or substantially parallel to the axes of rotation of the folding rolls, the segments of the compressed air means being arranged side by side in the first feeding direction or in succession in the second feeding direction , In this way, the printed sheet can advantageously be provided either in a first feed direction extending essentially at right angles to the axes of rotation of the folding rolls and subjected to the compressed air impact transversely to the first feed direction or in a second feed direction running essentially parallel to the axes of rotation of the folding rolls and longitudinally to the second Feeding direction with the Compressed air shock are applied. Accordingly, the sheet is either transversely or longitudinally folded.

In one embodiment of the device according to the invention, at least one first guide element for the printed sheet is arranged substantially in the guide plane. In addition, at least one second guide element for the printed sheet is formed, which is arranged between the at least one, first guide element and the compressed air device and extends directly into the region of the outlet openings of the segments. As a result, the two trailing ends of a sheet conveyed into the folding gap between the folding rollers can also be guided in a defined manner.

According to a further embodiment of the device according to the invention, at least one first and one second folding positions arranged in the guide plane are formed in the second feed direction one behind the other and are arranged at a distance from one another. Downstream of the folding rollers at least two removal lines for printed sheets are arranged. In this case, the first removal path is formed at least one provided in the first folding position sheet and the second removal path at least one provided in the second folding positions printable recordable. Accordingly, in another embodiment of the method according to the invention, the printing sheet is provided in one of at least two folding positions provided one behind the other in the second feeding direction. The respective folding position is selected according to a given production order and the compressed air impact is only on the provided in the folding position sheet. The sheet is taken after folding of one of at least two removal lines.

Finally, in a further embodiment of the method according to the invention, at least two successive printed sheets are each provided in a different one of the at least two provided folding positions and, after folding, respectively taken up by a different one of the at least two removal sections.

Due to the design of the device with at least two folding positions and with at least two associated with the folding positions Abtransportstrecken and due to the segmental loading of the compressed air device, a subsequent sheet can be advantageous already transported into the device when a leading sheet has not yet reached its folding position. Thus, a significant performance increase of the inventive method is possible. In addition, the printed sheets can be divided particularly easily with this solution to at least two product streams, whereby a corresponding switch function of a upstream or downstream device can be saved. Likewise, for example, by means of the second folding position and cooperating with this Abtransportstrecke a rejection not the quality requirements corresponding sheet possible, while parallel to the production continues on the first folding position and cooperating with this removal distance.

According to a further embodiment of the device according to the invention, at least one first and one second folding position are formed in the guide plane, in succession in the second feeding direction, and are arranged overlapping one another. In this case, downstream of the folding rollers, a common removal path is arranged, which is at least one provided in the first folding position sheet and at least one sheet provided in the second folding position formed overlapping each other in the second feed direction recordable. During operation of this device, at least two successive printed sheets are each provided overlapping each other in another of at least two folding positions provided in succession in the second feeding direction. For this purpose, the respective folding position is selected according to a given production order. The compressed air impact takes place only on sheet in the folding position. The sheets are finally taken overlapping each other after folding from a common removal path. As a result, advantageously at least two overlapping product streams of folded printed sheets can be formed, transported together and further processed together or separately.

In a further embodiment of the device according to the invention, the latter has at least one first stop and at least one second stop arranged in the guide plane, wherein the second stop is arranged upstream of the first stop in the second feed direction. Both stops can be raised and / or raised via the guide plane formed lowerable under the management level. These optional stops are used to help provide the signature in the appropriate folding position.

According to a further embodiment of the device according to the invention, the compressed air device has an alignment plane extending parallel to and spaced from the guide plane and is arranged displaceable and / or pivotable in this alignment plane. As a result, the compressed air device can be displaced and / or pivoted parallel to the guide plane and a twisted supplied or positioned printed sheet can nevertheless be optimally conveyed to the folding rollers by means of a compressed air impact resulting from correspondingly aligned outlet openings.

In a further embodiment of the method according to the invention, after the compressed-air impact, at least one second compressed-air impact directed at the same pressure sheet takes place, the pressure and / or the duration of the second compressed-air impact being preferably chosen differently from the first compressed-air impact. Thus, the folding quality of the sheet can be further improved. In particular, for asymmetric geometry print sheets, i. in printed sheets with uneven number of pages, the formation of donkey ears at the trailing ends of the folded sheet can be avoided by at least one such additional compressed air impact.

In a further embodiment of the method according to the invention, the compressed air impact is suppressed to a printed sheet provided and this printed sheet is discharged in the guide plane. In this way, the discharge of non-quality documents corresponding sheet advantageously without an additional device, that can be realized easily and inexpensively.

According to a further embodiment of the device according to the invention, the at least one control element of at least one segment of the compressed air device can be controlled by the control unit in such a way that a period of time for the at least one outlet opening of this segment to be pressurized with compressed air and / or a cross-sectional area of this outlet opening and / or a pressure thereof Outlet feedable air pressure to the properties of the provided sheet are customizable.

For this purpose, in the method according to the invention, the duration of the action of the at least one outlet opening of at least one segment of the compressed air device with compressed air and / or the cross-sectional area of this outlet opening and / or the pressure of the compressed air supplied to this outlet opening is changed by means of the control unit and the control unit triggers a correspondingly to the characteristics of provided printed sheet modified compressed air shock.

According to a further embodiment of the device according to the invention, the segments of the compressed air device advantageously each have at least one first control element for varying the duration of the pressurization of the at least one outlet opening with compressed air and / or at least one second control element for changing the cross-sectional area of this outlet opening and / or at least one third control element for changing a pressure of the compressed air that can be supplied to this outlet opening.

In a further embodiment of the device according to the invention, at least one segment of the compressed air device has at least two first outlet openings with equal cross-sectional areas and at least two second outlet openings with equal cross-sectional areas, wherein the cross-sectional areas of the first outlet openings preferably have a different size to the cross-sectional areas of the second outlet openings. Furthermore, this segment has at least one control element and at least one other control element for varying the duration of the pressurization of the outlet openings with compressed air and for changing the cross-sectional areas of the outlet openings, wherein the first outlet openings are connected to one control element and the second outlet openings are connected to the other control element. In addition to these controls, this segment has at least one further control element connected to the outlet openings for varying a pressure of the compressed air which can be supplied to the outlet openings.

The duration of pressurization of the first and second outlet openings with compressed air and the cross-sectional areas of the outlet openings are respectively modified by applying the first outlet openings through the one control element and the second outlet openings through the other control element according to the properties of the sheet to be folded provided In addition, optionally a pressure of the outlet openings supplied compressed air is changed by acting on the at least one, connected to the outlet openings, further control element.

With this device or with the corresponding method, both the cross-sectional areas of the outlet openings of the compressed air device and the duration of pressurization of these outlet openings can be changed very easily, quickly and precisely, whereby both the folding quality and the folding performance can be further improved in a cost effective manner ,

Fig. 1

schematische Vorderansicht eines ersten Ausführungsbeispiels der erfindungsgemäßen Vorrichtung, für quer zur Zuführrichtung zu falzende Druckbogen,

Fig. 2

schematische Vorderansicht eines zweiten Ausführungsbeispiels der erfindungsgemäßen Vorrichtung, für längs zur Zuführrichtung zu falzende Druckbogen,

Fig. 3

eine auszugsweise, schematische Seitenansicht der Vorrichtung aus Figur 2, jedoch in einem weiteren Ausführungsbeispiel mit drei Segmenten der Drucklufteinrichtung und mit einer Falzposition für die Druckbogen,

Fig. 4

eine vergrösserte, schematische Darstellung eines Schnitts durch eines der in Fig. 3 dargestellten Segmente der Drucklufteinrichtung, mit mehreren in einer Reihe angeordneten Austrittsöffnungen,

Fig. 5a

eine auszugsweise, schematische Seitenansicht der Vorrichtung in ähnlicher Darstellung wie in Fig. 3, jedoch in einem weiteren Ausführungsbeispiel, ausgestattet mit sechs Segmenten der Drucklufteinrichtung und mit zwei voneinander beabstandeten Falzpositionen für die Druckbogen, in einem ersten Verfahrensschritt,

Fig. 5b

eine Ansicht entsprechend Fig. 5a, jedoch in einem zweiten Verfahrensschritt,

Fig. 5c

eine Ansicht entsprechend Fig. 5a, jedoch in einem weiteren Ausführungsbeispiel mit zwei einander überlappenden Falzpositionen für die Druckbogen,

Fig. 5d

eine Ansicht entsprechend Fig. 5c, jedoch in einem zweiten Verfahrensschritt und zusätzlicher Darstellung von in einer ersten Zuführrichtung überlappend abtransportierten Druckprodukten,

Fig. 6

eine von unten betrachtete Ansicht der Drucklufteinrichtung gemäss Fig. 3, mit in einer Reihe angeordneten Austrittsöffnungen und einem verdreht zugeführten, zu falzenden Druckbogen,

Fig. 7

Eine Ansicht eines weiteren Ausführungsbeispiels funktionell ähnlich der Fig. 6, jedoch mit in drei Reihen angeordneten Austrittsöffnungen der Drucklufteinrichtung und einem verdreht zugeführten, zu falzenden Druckbogen.

The invention will be explained in more detail with reference to figures. Show it:

Fig. 1

schematic front view of a first embodiment of the device according to the invention, for transverse to the feed direction to sheet to be folded,

Fig. 2

schematic front view of a second embodiment of the device according to the invention, for longitudinally to the feed direction to be folded sheet,

Fig. 3

a partial, schematic side view of the device FIG. 2 but in a further embodiment with three segments of the compressed air device and with a folding position for the printed sheets,

Fig. 4

an enlarged, schematic representation of a section through one of in Fig. 3 illustrated segments of the compressed air device, with a plurality of outlet openings arranged in a row,

Fig. 5a

a partial, schematic side view of the device in a similar representation as in Fig. 3 but in a further embodiment, equipped with six segments of the compressed air device and with two spaced-apart folding positions for the printed sheets, in a first method step,

Fig. 5b

a view accordingly Fig. 5a but in a second process step,

Fig. 5c

a view accordingly Fig. 5a but in another embodiment with two overlapping fold positions for the signatures,

Fig. 5d

a view accordingly Fig. 5c but in a second method step and additional representation of printed products which are transported in an overlapping manner in a first feed direction,

Fig. 6

a bottom view of the compressed air device according to Fig. 3 with arranged in a row outlet openings and a twisted supplied, to be folded sheet,

Fig. 7

A view of another embodiment functionally similar to Fig. 6 but with outlet openings arranged in three rows the compressed air device and a twisted supplied, to be folded sheet.

According to the in Fig. 1 1, a device according to the invention for the transverse folding of each having at least two printed pages 1, a guide plane 3, in each of which a sheet 1 fed and provided for folding and is forwarded from the sheet 1 for folding. Of course, the guide plane 3, which extends horizontally here, can also be arranged vertically or at any angle in space, which, depending on the specific conditions of use, enables a large number of constructional options. Although here and also for simplification reasons only a single sheet 1 described and in the figures, only a single sheet 1 is shown, it is in each case at least one sheet 1, that is either actually about a single or more superimposed Sheet 1.

On a first side 4 of the guide level 3, which is shown in the first embodiment for illustrative reasons below the guide level 3, two folding rollers 5 are arranged. These each have an axis of rotation 6 and form between them a folding gap 7 for on a prepared or on a non-prepared fold line 8 to be folded sheet 1 from. The axes of rotation 6 of the folding rollers 5 are aligned both parallel to one another and parallel to the guide plane 3. On one of the first side 4 of the guide level 3 opposite, second side 9 of the guide level 3, which in the in Fig. 1 shown first embodiment is shown above the guide level 3, a compressed air device 10 is arranged in the region of the folding gap 7. The compressed air device 10 of the device 2 is formed segmented. It has at least two, but preferably more than two, in a substantially perpendicular to the axes of rotation 6 of the folding rollers 5 extending, first feed direction 26 juxtaposed segments 32. Each segment 32 has at least one, but preferably a plurality of directed to the folding gap 7 outlet openings 11th for compressed air 12 and is via a compressed air line 13 with a compressed air source 14 and this in turn connected via a control line 15 to a control unit 16 of the device 2. In addition, each segment 32 has a designed as a solenoid valve, for example, first control element 17 for varying the duration of exposure of the at least one outlet opening 11 with compressed air 12, a here designed as a slide, for example, second control element 18 for changing a cross-sectional area 19 of the outlet opening 11 and an example formed as a pressure reducing valve, arranged in the compressed air line 13, third control element 20 for changing a pressure of the outlet opening 11 can be supplied with compressed air 12. The controls 17, 18, 20 are each connected via a control line 15 to the control unit 16.

Essentially, in the guide plane 3 of the device 2, a first guide element 21 is arranged for the printing sheet 1 resting thereon during the provision and with a recess 22 formed in the region of the folding gap 7 for the printed sheet 1 and for each of the outlet openings 11 in the form a compressed air surge 12 'ejected compressed air 12 is provided. In addition to the first guide element 21, a second guide element 23 is provided for the printing sheet 1, which is arranged between the first guide element 21 and the compressed air device 10 and possibly cooperates with the first guide element 21.

As the first guide member 21, for example, a guide table can be used. Of course, instead of a single guide table and a plurality of narrow guide elements spaced from each other, ie, arranged side by side and / or. As in Fig. 1 illustrated, the first guide member 21 may be extended in the region of its recess 22 from the guide level 3 to near the area of the folding rollers 5, to ensure better management of the sheet 1 to the folding rollers 5. As a second guide member 23 may also be a fixed element, such as a guide plate, use. The second guide element 23 extends directly into the region of the outlet openings 11 of the segments 32, so that advantageously also the two trailing ends of the sheet 1 fed into the folding gap 7 between the folding rollers 1 can be guided defined by the second guide member 23. Of course, the second guide member 23 may have a plurality of narrow individual elements, which are spaced apart, juxtaposed and / or arranged one behind the other. Like the guide plane 3 of the device 2, the first and the second guide element 21, 23 can also be arranged horizontally, vertically or at any angle in space, depending on the specific conditions of use.

Finally, the device 2 has a transport unit 24, consisting of an upper conveyor belt 25 and two circulating lower conveyor belts 25 ', 25 ", with which the printed sheets 1 in the substantially perpendicular to the axes of rotation 6 of the folding rollers 5 extending first feed direction 26 is provided Thus, the device 2 can be used for the transverse folding of printed sheet 1.

According to one in Fig. 2 illustrated, a second longitudinal direction of each having at least two printed pages having printed sheet 1, inventive device 2 'has a parallel to the axes of rotation 6 of the folding rollers 5 extending, second feed direction 26' for the sheet 1 and, accordingly, also parallel to the axes of rotation 6 of the folding rollers 5 extending, second transport unit 24 'with upper and lower conveyor belts 27, 27' on. The further components of the device 2 'essentially correspond to the device 2 described for the first exemplary embodiment, the segments 32 of the compressed air device 10 being arranged one behind the other in the second feed direction 26' of the printed sheet 1.

When operating in the Fig. 1 and 2 Devices 2, 2 'obtained, the segments 32 of the compressed air device 10 via the control unit 16 each receive a trigger pulse for a directed to the folding line 8 of the respective sheet 1 compressed air surge 12' through the at least one outlet opening 11. In this case, a period of exposure of the at least one Outlet opening 11 of the segments 32 with compressed air 12 and / or a cross-sectional area 19 of this outlet opening 11 and / or a pressure of this outlet opening 11 supplied compressed air 12th adapted to the properties of the printed sheet 1 provided and changed by means of the control unit 16. The properties of the supplied printed sheets 1 are known in advance to the control unit 16, which activates the first control element 17 and / or the second control element 18 and / or the third control element 20 with changing properties of the sheet 1 to be folded. In this case, the time duration of the admission of the at least one outlet opening 11 of the segments 32 with compressed air 12 is changed in each case by activating the first control element 17. The cross-sectional area 19 of this outlet opening 11 is changed in each case by activation of the second control element 18. Changing the pressure of the compressed air 12 which can be supplied to this outlet opening 11 takes place in each case by activation of the third control element 20.

In this case, the compressed air surge 12 'corresponding to the control unit 16 respectively known feeding speed of a sheet 1 are triggered, the time until the impact of the compressed air 12 is to include the fold line 8 of this sheet 1. Of course, the compressed-air impact 12 'can also be triggered on the basis of an actual position of the printed sheet 1 detected, for example, by means of a sensor (not shown). In addition, the triggering time of the compressed air surge 12 'can also be varied. In this way, successive printing sheets 1 can be provided in different folding positions, so that the folded printed sheets 1 overlap one another in the first or in the second feeding direction 26, 26 'and can be separated at the overlapping points for further processing if required.

Under the action of the compressed-air impact 12 ', the printed sheet 1 is guided at its fold line 8 into the folding gap 7 located between the folding rollers 5 and there either folded transversely (FIG. Fig. 1 ) or longitudinally folded ( Fig. 2 ). The folding rollers 5 then transport the folded printed sheet 1 to a removal section 28 (not shown).

Downstream of the folding rollers 5, an unillustrated sensor can be arranged, which dog ears, stapes, etc. recognizes and corresponding signals to the connected to it control unit 16. After automatic evaluation of this information, the segments 32 of the compressed air device 10 or the respective compressed-air impact 12 'can be correspondingly controlled in order to avoid such quality defects in the future. Thus, the compressed air device 10 and thus the entire device 2, 2 'formed self-learning.

If a pressure sheet 1 which does not meet the quality requirements is provided in the apparatus 2, 2 'and detected by a sensor, not shown, the control unit 16 can suppress the respective trigger pulse for a compressed-air impact 12', so that this printed sheet 1 is conveyed by means of the respective transport unit 24 , 24 'in the management level 3 to a Ausschleusstrecke 29 (not shown) Fig. 1 ) and thus discharged from the device 2, 2 '. Therefore, advantageously, a corresponding switch function of an upstream or downstream device can be saved.

According to a Fig. 3 shown, another embodiment of the device 2 ', both the compressed air device 10 and the folding rollers 5 each have a longitudinal extent a, b, which are formed substantially the same size but of course can also be designed differently large. The segmented compressed air device 10 of the device 2 'has three segments 32, which are arranged one behind the other in the second feed direction 26' of the device 2 '. Of course, compressed air devices 10 having only two or more than three segments 32 may also be used. Each segment 32 of the compressed air device 10 is formed separately controllable with compressed air 12 and has an outlet opening 11 for the compressed air 12. Of course, per segment 32 also a plurality of outlet openings 11 may be used and in at least one row 31 (FIG. Fig. 4 ) to be ordered.

As in Fig. 3 illustrated, the segments 32, for example, each have their own, also designed as a solenoid valve, first control element 17 and connected via a respective compressed air line 13 to the compressed air source 14. In addition, the segments 32 each have a second, designed as a slider example control 18 and in each case a third, designed as a pressure-reducing valve control 20 on. For reasons of clarity, all the control lines 15 are here shown by the control unit 16 to the first control elements 17 and the compressed air source 14, while only one of the control lines 15 to the second and the third control elements 18, 20 has been shown. Of course, instead of one compressed air line 13 per segment 32, only a single compressed air line 13 can be arranged for all segments 32, or the segments 32 can be grouped and several segments 32 supplied via a common compressed air line 13. In this case, appropriately arranged, not shown here controls for the required loading of the segments 32 and their outlet openings 11 with compressed air 12th

The outlet openings 11 of the segments 32 each have a cross-sectional area 19, wherein the size of the cross-sectional areas 19 can be changed, for example, by using correspondingly adjustable shutters (not shown here) controlled by the second control element 18. The shape of the cross-sectional areas 19 is arbitrary, i. For example, round, semicircular or elliptical, but also rectangular, triangular or slit-shaped cross-sectional areas 19 can be used. As an alternative to changing the size of the cross-sectional areas 19 or in addition, the compressed air 12 can be supplied to the outlet openings 11 respectively by a corresponding, via the control unit 16 subsequent activation of the third control element 20 with different pressure. Also alternatively or additionally, finally, by means of the first control elements 17 and the duration of the loading of the segments 32 and thus the outlet openings 11 can be changed with compressed air 12.

Should with the in Fig. 3 2 'shown a longitudinal fold in a sheet 1 are generated, the respective sheet 1 is therefore clocked in the second feed direction 26' centrally and parallel to the axes of rotation 6 of the folding rollers 5 and thus supplied in parallel to the compressed air device 10 and in a folding position 33 for Folded provided. Accordingly, the control unit 16 solves a compressed air surge 12 'through the outlet openings 11 of the segments 32 of the compressed air device 10 via control lines 15 connected to the first control elements 17 out as soon as the respective sheet 1 has reached the folding position 33. Depending on the control unit 16 known properties of the sheet 1, such as the format, the grammage and the speed, the control unit 16 determines the required pressure of the generated compressed air surge 12 'and adjusts this by means of the third control element 20 accordingly or adjusts this if necessary. In addition or as an alternative, by means of the control unit 16 and via the second control element 18, the cross-sectional areas 19 of the outlet openings 11 and / or via the first control elements 17, the duration of the application of the respective segment 32 and thus the duration of the compressed-air impact 12 'can be adjusted. The average duration of a compressed-air surge 12 'is approximately 5 to 10 milliseconds (ms) and the pressure used is in the range of approximately 300 to 800 kPa (3 to 8 bar). Due to the force of the compressed-air impact 12 ', the mostly multilayer printed sheet 1 is transported out of the guide plane 3 out to the rotating folding rollers 5, ie pressed against the folding rollers 5 almost flatly. In this case, the sheet 1 is first in the range of its by the impact of compressed air 12 leading fold line 8 and finally completely between the folding rollers 5, that is drawn in the seam gap 7, pressed there at the fold line 8 and finally forwarded down to the untranslated removal section 28 ,

Due to the variability of the size of the cross-sectional areas 19 and the additional or alternative, with different pressure and / or time duration supplying the compressed air 12 to the outlet openings 11, the device 2 'relatively simple and fast according to the characteristics of the respective sheet 1 and according to the Requirements of a current production order are adjusted or adjusted.

The Fig. 4 shows a schematic representation of a section through a in Fig. 3 represented segment 32 of the compressed air device 10. In this additional variant, the segment 32 has two separate, connected to the compressed air source 14 and each by means of a likewise designed as a solenoid valve control 17 ', 17 "both for varying the time duration of the application of the outlet openings 11 ', 11 "with compressed air 12 as well as for changing cross-sectional areas 19', 19" of the outlet openings 11 ', 11 "provided compressed air lines 13', 13". In addition, the segment 32 in each case one to the compressed air lines 13 ', 13 ", arranged in the interior of the segment 32 distribution line 30', 30" for four first and second outlet openings 11 ', 11 ", wherein the first outlet openings 11' with one control element 17 'and the second outlet openings 11 "are connected to the other control element 17." Instead of the four outlet openings 11', 11 "shown here, two, three or more than four outlet openings can of course also be connected to the distribution line 30 '. The cross-sectional areas 19 ', 19 "of the outlet openings 11', 11" belonging to the same distribution line 30 ', 30 "are in each case of the same size, the size being the same as that of the four different distribution line 30 ', 30 "belonging outlet openings 11", 11' so different that the four first outlet openings 11 'each with a larger a cross-sectional area 19 'and the four second outlet openings 11 "are each formed with a smaller cross-sectional area 19".

If, for example, both control elements 17 ', 17 "are opened, this results in a high pressure of the compressed air 12 available in the segment 32, ie a relatively strong compressed-air impact 12' Controls 17 ', 17 "closed, the segment 32 is inactive. If only the control 17 "connected to the respective outlet openings 11" equipped with a small cross-sectional area 19 is opened, a weak compressed-air impact 12 'results, while a medium-pressure compressed-air impact 12' is produced, if only that with the respective larger cross-sectional area By opening or closing both control elements 17 ', 17 ", the time duration of the loading of the segment 32 with compressed air 12 is also changed. In addition to this, the supply of the compressed air 12 to the outlet openings 11 ', 11 "of the segment 32 can take place with different pressure, by a further control element 20' arranged in the compressed air line 13 leading to the compressed air source 14, for example designed as a pressure reducing valve the control unit 16, not shown here is acted upon accordingly. In Fig. 4 is indicated by dash-dotted lines, that for this purpose the two compressed air lines 13 ', 13 "are brought together to the compressed air line 13.

During operation of the device 2 ', a plurality of outlet openings 11', 11 "of a segment 32 connected to the same control element 17 ', 17" are thus actuated together with compressed air 12. By appropriate action on the control elements 17 ', 17 ", 20', the compressed-air impact 12 'of a segment 32, several or all segments 32 can be dosed easily and quickly according to the properties of the printed sheet 1 provided in the folding position 33.

Of course, the cross-sectional areas 19 ', 19 "of the first and second outlet openings 11', 11" of the segment 32 of the compressed air device 10 may be the same size, but then only a smaller gradation of the dosage of a compressed-air surge 12 'is achieved, as with the Likewise, the cross-sectional areas 19, 19 ', 19 "of the outlet openings 11, 11', 11" of different segments 32 can have a different size and / or compressed air 12 can reach the outlet openings 11, 11 '. , 11 "different segments 32 supplied with different pressure and / or the time duration of the application of different segments 32 are selected differently with compressed air 12.

By taking at least one of these measures, the segments 32 can advantageously trigger identical or different bursts of compressed air 12 '. As a result, the folding process can be optimally matched to the properties of a sheet 1 to be folded, such as grammage, size, coefficient of friction, porosity, ink coverage, etc., already specified above, and thus a consistently good folding quality can be achieved. In addition, a deviation from the folding position 33 of the printed sheet 1 provided can be at least partially corrected by using at least one of these measures. When Querfalzen asymmetrically folded sheets 1, which have, for example, different numbers distributed over the sheet 1 number of pages, belaufschlagt with corresponding different Druckluftstössen 12 ' compressed air surges 12 'from the at least one outlet opening 11 "with a smaller cross-sectional area 19" and / or at a lower pressure and / or over a shorter period of time than at locations with greater arch thickness at locations with a smaller arc thickness.

As in Fig. 4 and in Fig. 6 2, the outlet openings 11, 11 ', 11 "of the segments 32 of the compressed air device 10 are arranged in a row 31, which is formed in a plane, not shown, extending substantially perpendicularly through the guide plane 3. As a result, a device 2 in FIG. 2 'in the first and the second feed direction 26, 26' correctly provided sheet 1 by means of the respective generated compressed air pulses 12 'accurately and safely conveyed to the folding rollers 5 and folded there in high quality.

The Fig. 5a and 5b show in a further exemplary embodiment in each case a schematic side view of a device 2 "for longitudinal folding of printed sheets 1 ', 1", wherein for reasons of clarity already in the FIGS. 1 to 4 have been omitted controls shown. The compressed air device 10 of this device 2 "is equipped with three downstream segments 32 'and with three upstream segments 32" and has two in the second feed direction 26' successively arranged folding positions 33 ', 33 ", in which sheet 1', 1" with the only indicated here, the second transport unit 24 'and on the first guide member 21 are provided. To assist in providing a signature 1 'in the first folding position 33', the device 2 "is provided with a first stop 35 'arranged in the guide plane 3 and at a downstream end 34 of the device 2". To support the provision of a printing sheet 1 "in the second folding position 33", at least one further stop 35 "is arranged upstream of the at least one first stop 35 'and spaced from the first stop 35' by an over-sized value. can be raised via the management level 3 and / or formed lowerable under the management level 3. Opposite in the Figures 1 and 2 shown devices 2, 2 ', the device 2 "two removal lines 28', 28" for folded sheet 1 ', 1 "on.

Analogously to the device 2 ', the device 2 "is supplied with a first printed sheet 1' in the second feed direction 26 'in the middle and parallel to the axes of rotation 6 of the folding rollers 5, ie provided for folding Feeding direction 26 'successively provided folding positions 33', 33 ". The respective folding position 33 ', 33 "is selected according to a given production order and the compressed-air impact 12' takes place in each case only in the folding position 33 ', 33". Accordingly, the control unit 16 triggers via the first control element 17 a compressed air surge 12 'through the outlet openings 11 of the segments 32' of the compressed air device 10 as soon as the signature 1 'has reached the desired folding position 33' In the case of this solution, the devices 2, 2 'can also transport a printing sheet 1', 1 "which does not meet the quality requirements to the removal path 29 by means of the transport unit 24 'in the guide plane 3 and thus be discharged from the device 2" 35 'is either raised above the guide level 3 or lowered below it, which is why a corresponding switch function of an upstream or downstream device can also be saved in this exemplary embodiment.

In Fig. 5a the device 2 "is shown in a first method step, in which first the first printed sheet 1 'supplied in the guide plane 3 has been provided in the first folding position 33' on the first stop 35 ' Time has likewise already been partially introduced into the device 2 "For triggering a compressed-air impact 12 'and thus for feeding the first printed sheet 1' to the folding rollers 5, by actuation of their first control elements 17, only the three downstream segments 32 'in the feed direction 26' are the compressed air device 10 is supplied with compressed air 12, while the three upstream segments 32 "are turned off. The folded first printed sheet 1 'is then forwarded by the folding rollers 5 to the first removal path 28'.

Due to the design of the device 2 with two folding positions 33 ', 33 "and two removal lines 28', 28" and due to the segmental loading the compressed air device 10, the subsequent sheet 1 "advantageously already in the device 2" are transported when the leading sheet 1 'has not reached its folding position 33' yet.

The subsequent printing sheet 1 "can then be conveyed either to the same folding position 33 'on the first stop 35' or as in Fig. 5b as second method step, are provided in the further upstream second folding position 33 "after previously lifting the second stopper 35" into the guiding plane 3 of the device 2 "by acting on only the upstream segments 32" of the compressed air device 10 this sheet 1 "then also promoted to the folding rollers 5, there folded and the second removal section 28" passed. By taking place in this way division of the sheet 1 in two separately to be folded and to separate evacuation routes 28 ', 28 "weiterzuleitende product streams, the sheet 1', 1" in the device 2 "already belonging together forming sheet 1 ', 1" , which will later each give a common book block to be separated. In this case, the device 2 "can be operated by means of the control unit 16 depending on the current production order such that the printed sheets 1 ', 1" are alternatively provided in one of the two folding positions 33', 33 "and thus the corresponding removal section 28 ', 28". be supplied. In addition to the already described above unfolded blank sheet 1 ', 1 "on the Ausschleusstrecke 29 here also folded, the quality requirements not appropriate sheet 1', 1" on one of the Abtransportstrecken 28 ', 28 "are discharged, while the production on the other removal route 28 ", 28 'continues.

The Fig. 5c and 5d show a further similar embodiment, with a device 2 "', with the place of the two spaced apart folding positions 33', 33" of the Fig. 5a and 5b two folding positions 36 ', 36 "overlapping one another in the second feed direction 26' and a common removal distance 37 for overlapping printed sheets 1 ', 1" are formed. For this purpose, the two stops 35 ', 35 "are spaced apart from one another by a sub-format value After subsequent further processing, a product stream 38 can be advantageously produced on the common removal path 37, partially overlapping (see double arrow), folded printed sheet 1 ', 1 "in the second feed direction 26', which later either form a common book block or again Of course, with this device 2 "'by repeatedly successively providing printing sheet 1' in the first folding position 36 'or by repeatedly successively providing printing sheet 1" in the first folding position 36' and / or in the Second folding position 36 "also an unillustrated, second product stream from each other in the second feed direction 26 'partially overlapping sheet 1', 1" are generated, in which several consecutive sheet 1 'or more consecutive sheet 1 "also transverse to partially overlap second feeding direction 26 '.

Both at the in the FIGS. 5a and 5b as well as in the in the FIGS. 5c and 5d illustrated embodiments, the compressed air joint 12 'even before reaching the respective folding position 33, 33', 33 ", 36 ', 36" are triggered to', the sheet 1 ', 1 "by a corresponding, transversely to the feed direction 26' occurring deformation such to stiffen that by abutment of the sheet 1 ', 1 "to the stops 35', 35" existing risk of deformation in the feed direction 26 'can be excluded.

With appropriate design of the second transport unit 24 ', for example, with an upper and lower conveyor belts 25, 25', 25 ", of course, both the device 2" ( FIGS. 5a and 5b ) as well as the device 2 "'( FIGS. 5c and 5d In this case, the provision of the printing sheets 1 ', 1 "in the respective folding position 33', 33", 36 ', 36 "takes place exclusively by means of the second transport unit 24' and the guide elements 21, 23. The stops 35 ', 35 "can then optionally serve to support the provision of the printed sheets 1', 1" serve.

As in Fig. 6 indicated by double arrows, which also has three segments 32 having compressed air device 10 in a parallel and spaced from the guide plane 3, not shown, the device 2 'extending alignment plane 39, for example, designed to be motorized and / or pivotable. Therefore, one of the device 2 'slightly shifted or twisted supplied sheet 1, the fold line 8 deviates from the row 31 of the outlet openings 11, by corresponding displacement and / or pivoting of the compressed air device 10 exactly at the fold line 8 pressurized air 12 and into the be transported between the fold rollers 5, not shown here formed fold 7. The corresponding offset, ie the absolute amount by which a sheet 1 to be folded is shifted or rotated in the guide plane 3, is determined by means of sensors, not shown, and forwarded to the control unit 16. Then, the control unit 16 acts on a servo motor, also not shown, which shifts the compressed air device 10 in the alignment plane 39 and / or pivots and thus compensates for the offset of the sheet 1.

Alternatively to the solution according to Fig. 6 show the Fig. 7 a further embodiment with a likewise three segments 32 having compressed air device 10, the outlet openings 11 in three parallel to the folding gap 7 extending rows 31 ', 31 ", 31"' are arranged. If an offset of the sheet 1 to be folded in the guide plane 3 is detected here by means of sensors, also not shown, the compressed air device 10 does not have to adapt the position of the outlet openings 11 as in the case of FIG Fig. 6 shown embodiment can be moved and / or pivoted in an alignment plane 39. Rather, to compensate for the offset sufficient control of the in the respective rows 31 31 ", 31 '' located outlet openings 11, which are parallel to the folding gap 7 and segmentally offset offset with compressed air 12 applied. At the in Fig. 7 For example, the displacement of the sheet 1 shown in the first row 31 'could include the outlet openings 11 of the upstream segment 32, the outlet openings 11 of the middle segment 32 arranged in the second row 31 ", and the outlet openings 11 of the downstream located in the third row 31"' Segments 32 are controlled by compressed air 12. To realize this solution can Of course, the outlet openings 11 of the compressed air device 10 in two or more than three, each aligned parallel to the folding gap 7 rows 31 and be arranged in more than three segments 32.

In all embodiments, to improve the folding quality, in particular to avoid dog-ears in the folded printed sheet 1, 1 ', 1 ", after the compressed air impact 12' at least a second on the same sheet 1 directed compressed air blast 12" take place (see. Figures 1 to 5c ), whose pressure and / or time duration is preferably selected differently with respect to the first compressed-air surge. Thus, the folding quality of the sheet can be further improved.

Claims (20)

1. Device of the folding printed sheets, comprising

   • a guide plane (3) in which a printed sheet (1, 1', 1") can be made available in a folding position (33, 33', 33", 36', 36"),

   • at least two folding rollers (5) arranged on a first side (4) of the guide plane (3), each having a respective axis of rotation (6) and forming between them a folding gap (7) for the printed sheet (1, 1', 1") to be folded, the axes of rotation (6) of which folding rollers (5) are oriented both parallel to one another and also substantially parallel to the guide plane (3),

   • a compressed air device (10) oriented substantially parallel to the axes of rotation (6) of the folding rollers (5) and arranged on a second side (9) of the guide plane (3) opposite to the first side (4) of the guide plane (3) and arranged in the region of the folding gap (7), which compressed air device (10) is connected to a compressed air source (14) and to a control unit (16), and has at least one outlet opening (11, 11', 11") for compressed air (12) directed at the folding gap (7),

   characterised in that the compressed air device (10) has at least two segments (32, 32', 32") each having at least one respective outlet opening (11, 11', 11 ") provided with a cross-sectional area (19, 19', 19"), wherein each segment (32, 32', 32") is connected to the compressed air source (14) and to the control unit (16), has at least one control element (17, 18, 20; 17' 17", 20') and is designed to be activatable separately with compressed air (12).
2. Device according to Claim 1, characterised in that the device (2, 2', 2", 2"') for making available the printed sheet (1, 1', 1") has a first feed direction (26) disposed substantially at right angles to the axes of rotation (6) of the folding rollers (5), or a second feed direction (26') disposed substantially parallel to the axes of rotation (6) of the folding rollers (5), and the segments (32, 32', 32") of the compressed air device (10) are arranged side-by-side in the first feed direction (26) or one behind the other in the second feed direction (26').
3. Device according to Claim 1 or 2, characterised in that at least one first guide element (21) for the printed sheet (1, 1', 1") is arranged substantially in the guide plane (3), and at least one second guide element (23) for the printed sheet (1, 1', 1") is arranged between the at least one first guide element (21) and the compressed air device (10), the second guide element (23) extending to the immediate vicinity of the outlet openings (11, 11', 11") of the segments (32, 32', 32").
4. Device according to either of Claims 2 and 3, characterised in that, in the guide plane (3), at least one first and one second folding position (33', 33") are formed one behind the other in the second feed direction (26') and the folding positions (33', 33") are arranged at a distance from one another, at least two delivery lines (28', 28") being arranged downstream of the folding rollers (5) and a first delivery line (28') being designed to be able to receive at least one printed sheet (1') made available in the first folding position (33'), and a second delivery line (28") being designed to be able to receive at least one printed sheet (1") made available in the second folding position (33").
5. Device according to either of claims 2 and 3, characterised in that, in the guide plane (3), at least one first and one second folding position (36', 36") are formed one behind the other in the second feed direction (26') and the folding positions (36' 36") are arranged overlapping one another, a common delivery line (37) being arranged downstream of the folding rollers (5), which common delivery line (37) is designed to be able to receive at least one printed sheet (1') made available in the first folding position (36') and at least one printed sheet (1") made available in the second folding position (36"), the printed sheets (1', 1") overlapping one another in the second feed direction (26').
6. Device according to any one of Claims 2 to 5, characterised in that at least one first and at least one second stop (35', 35") are formed in the guide plane (3), the second stop (35") being arranged upstream of the first stop (35') in the second feed direction (26'), and both stops (35' 35") being designed to be able to be raised above the guide plane (3) and/or to be able to be lowered below the guide plane (3).
7. Device according to any one of Claims 1 to 6, characterised in that the compressed air device (10) has an alignment plane (39) disposed parallel to and at a distance from the guide plane (3) and is arranged displaceably and/or swivellably in this alignment plane (39).
8. Device according to any one of Claims 1 to 7, characterised in that the at least one control element (17, 18, 20; 17', 17", 20') of at least one segment (30, 32', 32") of the compressed air device (10) can be activated via the control unit (16) in such a way that a duration of the supplying of the at least one outlet opening (11, 11', 11") of this segment (32, 32', 32") with compressed air (12), and/or a cross-sectional area (19, 19', 19") of this outlet opening (11, 11', 11"), and/or a pressure of the compressed air (12) which can be supplied to this outlet opening (11, 11', 11"), can be adapted to the characteristics of the printed sheet (1, 1', 1") made available.
9. Device according to any one of Claims 1 to 8, characterised in that the segments (32, 32', 32") of the compressed air device (10) each have at least one first control element (17) for varying the duration of the supplying of the at least one outlet opening (11) with compressed air (12), and/or at least one second control element (18) for varying the cross-sectional area (19) of this outlet opening (11), and/or at least one third control element (20) for varying a pressure of the compressed air (12) which can be supplied to this outlet opening (11).
10. Device according to any one of Claims 1 to 8, characterised in that at least one segment (32, 32', 32") of the compressed air device (10) has

    • at least two first outlet openings (11') with cross-sectional areas (19') of equal size and at least two second outlet openings (11") with cross-sectional areas (19") of equal size, the cross-sectional areas (19') of the first outlet openings (11') preferably being of a different size to the cross-sectional areas (19") of the second outlet openings (11 "),

    • at least one control element (17') and at least one other control element (17") for varying the duration of the supplying of the outlet openings (11' 11") with compressed air (12) and for varying the cross-sectional areas (19' 19") of the outlet openings (11', 11"), the first outlet openings (11') being connected to the one control element (17') and the second outlet openings (11") being connected to the other control element (17"),

    • at least one further control element (20') connected to the outlet openings (11', 11") for varying a pressure of the compressed air (12) which can be supplied to the outlet openings (11', 11").
11. Method for folding printed sheets, whereby

    • a printed sheet (1, 1', 1") is made available in a folding position (33, 33', 33", 36', 36") located in a guide plane (3),

    • on a first side (4) of the guide plane (3) the printed sheet (1, 1', 1") is folded in a folding gap (7) between at least two rotating folding rollers (5) each having a respective axis of rotation (6), the axes of rotation (6) being oriented both parallel to one another and also parallel to the guide plane (3),

    • in the region of the folding gap (7), from a second side (9) of the guide plane (3) opposite to the first side (4), a compressed air discharge (12') directed at the printed sheet (1, 1', 1") made available in the folding position (33, 33', 33", 36', 36") and using compressed air (12) likewise made available is triggered from at least one outlet opening (11, 11', 11") of a compressed air device (10) connected to a compressed air source (14) and to a control unit (16), and through the effect of the compressed air discharge (12') the printed sheet (1, 1', 1") made available is transported out of the guide plane (3) to the rotating folding rollers (5),

    characterised in that the compressed air device (10) has at least two segments (32, 32', 32") each having at least one outlet opening (11, 11', 11") provided with a cross-sectional area (19, 19', 19"), wherein each segment (32, 32', 32") is connected to the compressed air source (14) and to the control unit (16), has at least one control element (17, 18, 20; 17', 17", 20') and is activated separately with compressed air (12), and wherein the control unit (16) triggers a compressed air discharge (12') from the at least one outlet opening (11, 11', 11") of at least one of the segments (32, 32', 32") of the compressed air device (10) on to the printed sheet (1, 1', 1") made available.
12. Method according to Claim 11, characterised in that the printed sheet (1, 1', 1") is made available in a first feed direction (26) disposed substantially at right angles to the axes of rotation (6) of the folding rollers (5) and is impinged upon by the compressed air discharge (12') transversely to the first feed direction (26), or is made available in a second feed direction (26') substantially parallel to the axes of rotation (6) of the folding rollers (5) and is impinged upon by the compressed air discharge (12') longitudinally with respect to the second feed direction (26').
13. Method according to Claim 12, characterised in that, in order to compensate for a printed sheet (1, 1', 1") made available in a displaced position in the guide plane (3) and/or in a skewed position with respect to the feed direction (26, 26'), the compressed air device (10) is displaced and/or skewed correspondingly parallel to the guide plane (3).
14. Method according to Claim 12 or 13, characterised in that the printed sheet (1, 1', 1") is made available in one of at least two folding positions (33', 33") provided one behind the other in the second feed direction (26'), the respective folding position (33', 33") being selected according to a predetermined production order, the compressed air discharge (12') being applied only to the printed sheet (1, 1', 1") made available in the folding position (33', 33"), and the printed sheet (1, 1', 1") being received after folding by one of at least two delivery lines (28', 28").
15. Method according to Claim 12 or 13, characterised in that at least two successive printed sheets (1', 1") are in each case made available at a distance from one another in a respective other of at least two folding positions (33' 33") provided one behind the other in the second feed direction (26'), the respective folding position (33' 33") being selected according to a predetermined production order, the compressed air discharge (12') being applied in each case only to the printed sheet (1', 1") located in the folding position (33', 33") and the printed sheets (1', 1") each being received, after folding, by a respective other of at least two delivery lines (28', 28").
16. Method according to Claim 12 or 13, characterised in that at least two successive printed sheets (1', 1") are each made available overlapping one another in a respective other of at least two folding positions (36', 36") provided one behind the other in the second feed direction (26'), the respective folding position (36' 36") being selected according to a predetermined production order, the compressed air discharge (12') being applied in each case only to the printed sheet (1', 1") located in the folding position (36', 36"), and the printed sheets (1', 1") being received after folding by a common delivery line (37) while overlapping one another.
17. Method according to any one of Claims 11 to 16, characterised in that, after the compressed air discharge (12'), at least one second compressed air discharge (12") directed at the same printed sheet (1, 1' 1") takes place, the pressure and/or duration of the second compressed air discharge (12") preferably being varied with respect to the compressed air discharge (12').
18. Method according to any one of Claims 11 to 17, characterised in that the compressed air discharge (12') on to a printed sheet (1, 1', 1") made available is suppressed and this printed sheet (1, 1', 1") is ejected outwards in the guide plane (3).
19. Method according to any one of Claims in 11 to 17, characterised in that a duration of the supplying of compressed air (12) to the at least one outlet opening (11, 11', 11") of at least one segment (32, 32', 32") of the compressed air device (10) and/or a cross-sectional area (19) of this outlet opening (11, 11', 11") and/or a pressure of the compressed air (12) supplied to this outlet opening (11, 11', 11"), is/are adapted to the characteristics of the printed sheet (1, 1' 1") made available and for this purpose is/are varied by means of the control unit (16), and the control unit (16) triggers a compressed air discharge (12') modified according to the characteristics of the printed sheet (1, 1', 1") made available.
20. Method according to any one of Claims 11 to 17, characterised in that the at least one segment (32, 32', 32") of the compressed air device (10) has at least two first outlet openings (11') with cross-sectional areas (19') of equal size and at least two second outlet openings (11") with cross-sectional areas (19") of equal size, the cross-sectional areas (19') of the first outlet openings (11') preferably being of a different size to the cross-sectional areas (19") of the second outlet openings (11"), in that the at least one segment (32, 32', 32") is connected to at least one control element (17') and to at least one other control element (17") for varying the duration of the supplying of the outlet openings (11', 11") with compressed air (12) and for varying the cross-sectional areas (19', 19") of the outlet openings (11', 11"), the duration of the supplying of the first and second outlet openings (11', 11") with compressed air (12), and the cross-sectional areas (19', 19") of the outlet openings (11', 11"), being in each case varied in that the first outlet openings (11') are subjected to the influence of the one control element (17') and the second outlet openings (11") are subjected to the influence of the other control element (17"), a pressure of the compressed air (12) supplied to the outlet openings (11', 11") being, in addition, optionally varied by influencing at least one further control element (20') connected to the outlet openings (11', 11").

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