EP2727868B1 - 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, i. folded to the format of the later 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 and the thus generated, strong compressed air flow, however, this solution allows no adaptation to changing properties in succession to folding sheet. Such altered characteristics of the printed sheets can be, for example, their format, the number of printed pages per sheet and the grammage (grams per square meter) of the material used for the respective sheet. For example, the powerful blast of compressed air could crumple relatively light sheets, ie sheets of a small size and / or of thin paper, into the folding rolls. On the other hand, the compressed air impact on relatively heavy sheets could not be enough to transport them sufficiently fast to the folding rollers.

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 common to successive sheets with different properties. This applies inter alia to the format, the number of printed pages per printed sheet, the grammage and the prorosity of the material used, the coefficient of friction of the material surface, the residual moisture with or without upstream dryer and / or humidifier, the weight and friction distribution of the sheet with respect to its fold line, Color assignment values, electrostatic charge as well as temperature and humidity of the material. Of course, the properties of the printed sheets to be processed are also influenced by changing process and / or environmental conditions, such as the particular printing process used, the use of upstream dryer and / or humidifier or the temperature and humidity of the production room. Both the characteristics of the press sheets as well as the process and environmental conditions can either in the further processing process or taken from a database provided by a higher-level system.

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 per unit time larger amounts of substrate, which is both the quality and the performance of the devices used for further processing, such as Folding devices, much higher demands than before.

The object of the invention is therefore to provide an apparatus and a method for folding sheets, which allow for high folding quality and performance a simple and cost-effective adaptation to changing properties of successive sheets and therefore also suitable for further processing by digital printing machines sequentially printed sheet are.

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 device according to the invention has control elements connected to the compressed air source and the control unit for changing the duration of the loading of the at least one outlet opening of the compressed air device with compressed air and / or for changing a cross-sectional area of this outlet opening and / or for changing a pressure of the compressed air which can be supplied to this outlet opening. In this case, the control elements can be controlled via the control unit in such a way that the duration of the pressurization of the at least one outlet opening with compressed air and / or the cross-sectional area of this outlet opening and / or the pressure of the compressed air that can be supplied to this outlet opening can be adapted to the characteristics of the provided printed sheet. Accordingly, in the method according to the invention a duration of the admission of the at least one outlet opening the compressed air device with compressed air and / or a cross-sectional area of this outlet opening and / or a pressure of the compressed air supplied to this outlet opening adapted to the characteristics of the sheet provided and modified by means of the control unit.

By applying at least one of the control elements, the compressed air surge of the compressed air device can be simply and rapidly dosed according to the properties already mentioned above, such as grammage, format, coefficient of friction, porosity, ink coverage, etc. of a sheet currently being folded provided in the folding position and over the entire length Spectrum for folding sheet both a good folding quality and a high folding performance can be achieved.

In one embodiment of the device according to the invention, 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, the device 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 scattering element. In addition to these control elements, the device has at least one further control element connected to the outlet openings for changing 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 these outlet openings are respectively changed 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 In addition, a pressure of the compressed air which can be supplied to the outlet openings is optionally changed by acting on the at least one further control element connected to the outlet openings.

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 ,

In further embodiments of the device, the latter has, for the purpose of providing the printed sheet, either a first or second feed direction extending substantially at right angles or substantially parallel to the axes of rotation of the folding rolls. In this way, the printed sheets may advantageously be provided either substantially parallel or substantially at right angles to the axes of rotation of the folding rollers and, accordingly, either transversely or longitudinally folded.

In a further embodiment of the device, the compressed air device has at least two segments arranged one behind the other in the first feed direction or in the second feed direction, each having at least one outlet opening provided with a cross-sectional area, wherein each segment is connected to the compressed air source and the control unit, at least one control element has and is formed separately controllable with compressed air. The segments 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 which can be fed to this outlet opening , During operation of the device, each segment is controlled separately with compressed air and the control unit triggers a modified according to the characteristics of the sheet provided compressed air surge from the at least one outlet opening at least one of the segments of the compressed air device on the provided sheet.

Due to 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 individually to compressed air, so that within the device at least two consecutively provided printed sheets can advantageously be treated both identically and differently according to their properties. With appropriate action on at least one of the controls of at least one segment, the compressed air impact of at least one segment, several segments or the entire compressed air device can be simply and quickly metered according to the characteristics of the sheet provided in the respective folding position and both good folding quality over the entire spectrum for folding printed sheets as well as a high folding performance can be achieved.

In a further 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 compressed air device. 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 at least one printed sheet provided in the first folding position, and the second removal path is provided at least one in the second folding position Pressure sheet formed absorbable. 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 conveyed optimally 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 printing sheet advantageously without an additional device, i. be realized easily and inexpensively.

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 vergrösserte, schematische Darstellung eines Schnitts durch eine Vorrichtung gemäss Fig. 2, mit einer mit mehreren in einer Reihe angeordneten Austrittsöffnungen ausgestatteten Drucklufteinrichtung,

Fig. 4

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. 5

eine vergrösserte, schematische Darstellung eines Schnitts durch eines der in Fig. 4 dargestellten Segmente der Drucklufteinrichtung, mit mehreren in einer Reihe angeordneten Austrittsöffnungen,

Fig. 6a

eine auszugsweise, schematische Seitenansicht der Vorrichtung in ähnlicher Darstellung wie in Fig. 4, 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. 6b

eine Ansicht entsprechend Fig. 6a, jedoch in einem zweiten Verfahrensschritt,

Fig. 6c

eine Ansicht entsprechend Fig. 6a, jedoch in einem weiteren Ausführungsbeispiel mit zwei einander überlappenden Falzpositionen für die Druckbogen,

Fig. 6d

eine Ansicht entsprechend Fig. 6c, jedoch in einem zweiten Verfahrensschritt und zusätzlicher Darstellung von in einer ersten Zuführrichtung überlappend abtransportierten Druckprodukten,

Fig. 7

eine von unten betrachtete Ansicht der Drucklufteinrichtung gemäss Fig. 4, mit in einer Reihe angeordneten Austrittsöffnungen und einem verdreht zugeführten, zu falzenden Druckbogen,

Fig. 8

Eine Ansicht eines weiteren Ausführungsbeispiels funktionell ähnlich der Fig. 7, 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

an enlarged, schematic representation of a section through a device according to Fig. 2 with a compressed air device equipped with a plurality of outlet openings arranged in a row,

Fig. 4

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

Fig. 5

an enlarged, schematic representation of a section through one of in Fig. 4 illustrated segments of the compressed air device, with a plurality of outlet openings arranged in a row,

Fig. 6a

a partial, schematic side view of the device in a similar representation as in Fig. 4 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. 6b

a view accordingly Fig. 6a but in a second process step,

Fig. 6c

a view accordingly Fig. 6a but in another embodiment with two overlapping fold positions for the signatures,

Fig. 6d

a view accordingly Fig. 6c 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. 7

a bottom view of the compressed air device according to Fig. 4 with arranged in a row outlet openings and a twisted supplied, to be folded sheet,

Fig. 8

A view of another embodiment functionally similar to Fig. 7 , However, arranged in three rows outlet openings of 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 has at least one, but preferably a plurality of directed to the folding gap 7 outlet openings 11 for compressed air 12 and is connected via a compressed air line 13 to a compressed air source 14 and this in turn via a control line 15 to a control unit 16 of the device 2. In addition, the compressed air device 10 has an example designed as a solenoid valve, first control element 17 for varying the duration of the application 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 this outlet opening 11 and one, for example, designed 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 connected via a respective 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 printed sheet 1 resting thereon during the provision and provided 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 Führüngsebene 3 to near the region 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 to directly into the region of the outlet openings 11 of the compressed air device 10, so that advantageously the two trailing ends of the conveyed in the folding gap 7 between the folding rollers 5 printed sheet 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 a 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.

When operating in the Fig. 1 and 2 shown devices 2, 2 'receives the compressed air device 10 via the control unit 16, a trigger pulse for a directed to the fold 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 compressed air device 10 with compressed air 12 and / or a cross-sectional area 19 of this outlet opening 11 and / or a pressure of the outlet opening 11 supplied compressed air 12 adapted to the characteristics of the printed sheet 1 provided and modified 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 duration of the application of the at least one outlet opening 11 of the compressed air device 10 with compressed air 12 by activating the first control element 17 is changed. The cross-sectional area 19 of this outlet opening 11 is activated by activating the second control element 18 changed. Changing the pressure of the compressed air 12 which can be supplied to this outlet opening 11 is effected by activating 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 detects dog-ears, plaits, etc. and forwards corresponding signals to the control unit 16 connected to it. After automatic evaluation of this information, the compressed air device 10 or the compressed air surge 12 'can be controlled accordingly 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 in the device 2, 2 'provided a quality sheet not corresponding sheet 1 and this detected, for example by means of a sensor, not shown, the control unit 16, the trigger pulse for a compressed air shock 12 'suppress, so that this sheet 1 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.

The Fig. 3 shows a schematic representation of a section through the compressed air device 10, which in this additional variant to those in the Fig. 1 and 2 illustrated embodiments of 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 changing the duration of exposure of outlet openings 11', 11" of the compressed air device 10 with compressed air 12 and for changing In addition, the compressed air device 10 in each case has a distribution line 30 ', 30 which adjoins the compressed air lines 13', 13 "and is arranged in the interior of the compressed air device 10 for each of four first and second outlet openings 11 ', 11 ", wherein the first outlet openings 11' are connected to one control element 17 'and the second outlet openings 11" are connected to the other control element 17 ". Of course, in each case two, three or more than four outlet openings can be connected to the distribution line 30 'or to the distribution line 30 "instead of the four outlet openings 11', 11" shown here. 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, their size being dependent on the size of the four outlet openings 11 belonging to the respective other distribution line 30', 30"", 11 'so different that the four first outlet openings 11' are each formed with a larger cross-sectional area 19 'and the four second outlet openings 11" each having a smaller cross-sectional area 19 ".

This variant allows a relatively simple metering of the compressed-air surge 12 'of the compressed-air device 10. If, for example, the two control elements 17', 17 "are opened, this results in a high pressure available in the compressed-air device 10 Compressed air 12, ie a relatively strong compressed air surge 12 '. On the other hand, if the two control elements 17 ', 17 "are closed, the compressed air device 10 is inactive If only the control element 17" connected to the outlet openings 11 "equipped with a small cross-sectional area 19" is opened, a weak compressed-air impact 12' results medium compressed air blast 12 'is then generated when only the connected to each with a larger cross-sectional area 19' equipped outlet openings 11 'control 17' is open. By opening or closing both control elements 17 ', 17 ", the duration of pressurization of the compressed air device 10 is also changed with compressed air 12. Additionally or alternatively, the supply of compressed air 12 to the outlet openings 11', 11" of the compressed air device 10 with different pressure take place by a in the leading to the compressed air source 14 compressed air line 13 arranged, for example, designed as a pressure reducing valve, further control element 20 'is acted upon by the control unit 16, not shown here accordingly. In Fig. 3 is indicated by dotted lines that for this purpose the two compressed air lines 13 ', 13 "are combined to the compressed air line 13. Of course, all the cross-sectional areas of the outlet openings of the compressed air device 10 may be of equal size, but then only a smaller gradation of the dosage of a compressed air blast 12' is reached than with the described different sized cross-sectional areas 19 ', 19 ".

As in Fig. 3 and in Fig. 7 2, the outlet openings 11, 11 ', 11 "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 in the device 2, 2' in the first and the second feed direction 26, 26 'correctly provided sheet 1 by means of the generated compressed air impact 12' accurately and safely promoted to the folding rollers 5 and folded there in high quality.

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. In the in Fig. 4 shown Another embodiment of the device 2 ', the compressed air device 10 is formed segmented and has three segments 32 which are arranged in the second feed direction 26' of the device 2 'one behind the other. 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, a plurality of outlet openings 11 can be used per segment 32 and arranged in at least one row 31.

As in Fig. 4 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 control element 18 designed as a slide, for example, and in each case a third control element 20 designed as a pressure-reducing valve. For reasons of clarity, only the control lines 15 from the control unit 16 to the first control elements 17 and to the compressed air source 14 are shown here, while the illustration of the control lines 15 to the second and to the third control elements 18, 20 has been dispensed with. 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 freely selectable, ie, for example, round, semicircular or elliptical, but also rectangular, triangular or slit-shaped cross-sectional areas 19 can be used. Alternatively 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 each by a corresponding, via the control unit 16 successful 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. 4 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 triggers 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 as soon as the respective printed 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 the compressed air 12 leading fold line 8 and finally completely between the folding rollers 5, that is drawn in the folding gap 7, there pressed on the fold line 8 and finally forwarded down to the untranslated transport route 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. 5 shows in a schematic, substantially analog representation of Fig. 3 a section through a in Fig. 4 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, not shown, and each also by legs also designed as a solenoid valve control 17 ', 17 "both for changing the time duration of the application of the outlet openings 11 ', 11 "with compressed air 12 as well as for changing the cross-sectional areas 19', 19" of the outlet openings 11 ', 11 "provided compressed air lines 13', 13" .. In addition, the segment 32 each to the compressed air lines 13 ', 13 "subsequent distributed within the segment 32 distribution line 30 ', 30 "for four first and second outlet openings 11', 11", wherein the first outlet openings 11 'with the one control element 17' and the second outlet openings 11 "with the other control 17 "are connected. Of course, in each case two, three or more than four outlet openings can be connected to the distribution line 30 'or to the distribution line 30 "instead of the four outlet openings 11', 11" shown here. 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, their size being dependent on the size of the four outlet openings 11 belonging to the respective other distribution line 30', 30"", 11 'differ so that the four first outlet openings 11' are each formed with a larger cross-sectional area 19 'and the four second outlet openings 11", each having 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' (not shown here) arranged in the compressed air line 13 leading to the compressed air source 14, for example designed as a pressure reducing valve. is acted upon by the control unit 16, also not shown here accordingly.

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 The cross-sectional areas 19, 19 ', 19 "of the outlet openings 11, 11', 11" of different segments can likewise be described 32 formed differently sized and / or compressed air 12 to the outlet openings 11, 11 ', 11 "different segments 32 supplied with different pressure and / or the 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. In the case of transverse folding, asymmetrically folded printed sheets 1, which have, for example, different number of pages distributed over the printed sheet 1, can be subjected to correspondingly different compressed-air pulses 12 ', i. At locations with a smaller arch thickness, compressed air surges 12 'take place 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.

The Fig. 6a and 6b 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 5 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 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 liftable 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. 6a 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 ' Point in time has also been partially introduced into the device 2 "to trigger a compressed air blast 12 'and thus for supplying the first sheet 1' to the folding rollers 5 by corresponding actuation of its first control elements 17, only compressed air is supplied to the three downstream segments 32 'of the compressed air device 10 while the three upstream segments 32 "are turned off 28 'forwarded.

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 of the compressed air device 10, the following sheet 1 "advantageously already then in the device 2" transported when the leading Sheet 1 'has not yet reached its folding position 33'.

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. 6b 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 above-described discharging unfolded printing 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 continues on the other transport route 28", 28 '.

Of course, with appropriate design of the second transport unit 24 ', for example with an upper and lower conveyor belts 25, 25', 25 ", the device 2" can also be operated without the stops 35 ', 35 " Sheet 1 ', 1 "in the respective folding position 33', 33" exclusively by means of the second transport unit 24 'and the guide elements 21, 23. The stops 35', 35 "can then optionally to support the provision of the sheet 1 ', 1" serve.

The Fig. 6c and 6d show a further similar embodiment, with a device 2 "', with the place of the two spaced apart folding positions 33', 33" of the Fig. 6a and 6b 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. Depending on the subsequent further processing, a product stream 38 can thus advantageously be provided on the common removal path 37 from folded sheet 1 ', partially overlapping in the second feed direction 26'"are generated, which later either form a common book block or should be separated again. Of course, with this device 2 '"by repeatedly successively providing sheets 1' in the first folding position 36 'or by repeatedly successively providing sheets 1" in the second folding position 36 "and a non-illustrated, second product stream from each other in The second feed direction 26 'partially overlapping sheet 1', 1 "are generated in which a plurality of successive sheet 1 'or more consecutive sheet 1" also transversely to the second feed direction 26' partially overlap.

In the devices 2 "and 2", a compressed air surge 12 'even before reaching the respective folding position 33, 33', 33 "are triggered to the sheet 1, 1 ', 1 "by a corresponding, transverse to the feed direction 26' deformation such stiffening that by abutment of the sheet 1, 1 ', 1" to the stops 35', 35 "existing danger of deformation in the feed direction 26th 'can be excluded.

If the second transport unit 24 'is designed accordingly, for example with an upper and lower conveyor belts 25, 25', 25 ", it is of course also possible to operate the device 2 '" without the stops 35', 35 " the printing sheet 1 ', 1 "in the respective folding position 36', 36" exclusively by means of the second transport unit 24 'and the guide elements 21, 23. The stops 35', 35 "can then optionally to support the provision of the printed sheets 1 ', 1 " serve.

As in Fig. 7 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. 7 show the Fig. 8 3 shows a further exemplary embodiment with a compressed air device 10 likewise having three segments 32, whose outlet openings 11 are arranged in three rows 31 ', 31 "running parallel to the folding gap 7, If an offset of the sheet 1 to be folded in the guide plane 3 is detected here by means of likewise not shown sensors, the compressed air device 10 does not have to adapt the position of the outlet openings 11 as in the case of FIG Fig. 7 shown embodiment can be moved and / or pivoted in an alignment plane 39. Rather, to compensate for the offset a corresponding 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 is applied. At the in Fig. 8 For example, the displacement of the signature 1 shown in FIG. 1 could include the outlet openings 11 of the upstream segment 32 arranged in the first row 31 ', the outlet openings 11 of the middle segment 32 arranged in the second row 31 "and the downstream outlet openings 11 arranged in the third row 31'" Segments 32 are controlled by compressed air 12. To realize this solution, the outlet openings 11 of the compressed air device 10 may of course also be arranged in two or in more than three rows 31 aligned parallel to the folding gap 7 and 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. FIGS. 1, 2 . 4 and 6a to 6c ), 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. An apparatus for 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) disposed on a first side (4) of the guide plane (3), each having a rotational axis (6) and between them forming a folding gap (7) for the printed sheet (1, 1', 1") that is to be folded, the rotational axes (6) of said folding rollers (5) being oriented parallel to one another as well as substantially parallel to the guide plane (3),

   • a compressed-air device (10), oriented substantially parallel to the rotational axes (6) of the folding rollers (5) and located on a second side (9) lying opposite the first side (4) of the guide plane (3) in the region of the folding gap (7), said compressed-air device (10) being connected to a compressed-air source (14) and to a control unit (16) and having at least one outlet (11, 11', 11 ") for compressed air (12), which is directed at the folding gap (7),
   characterized in that the apparatus (2, 2', 2", 2"') includes control elements (17, 18, 20; 17', 17", 20'), connected to the compressed-air source (14) and to the control unit (16), for varying the duration of the supply of compressed air (12) to the at least one outlet (11, 11', 11") of the compressed-air device (10) and/or for varying the cross-sectional area (19, 19', 19") of said outlet (11, 11', 11") and/or for varying the pressure of the compressed air (12) delivered to said outlet (11, 11', 11"), in which case the control elements (17, 18, 20; 17', 17", 20') can be controlled via the control unit (16) in such a way that the duration of the supply of compressed air (12) to the at least one outlet (11, 11', 11") and/or the cross-sectional area (19, 19', 19") of said outlet (11, 11', 11") and/or the pressure of the compressed air (12) delivered to said outlet (11, 11', 11") can be adapted to the properties of the available printed sheet (1, 1', 1 ").
2. An apparatus according to Claim 1, characterized in that the compressed-air device (10) includes

   • at least two first outlets (11') having cross-sectional areas (19') of equal size and at least two second outlets (11") having cross-sectional areas (19") of equal size, the cross-sectional areas (19') of the first outlets (11') preferably differing in size from the cross-sectional areas (19") of the second outlets (11"),

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

   • at least one additional control element (20') connected to the outlets (11', 11") for varying the pressure of the compressed air (12) supplied to said outlets (11', 11").
3. An apparatus according to Claim 1 or 2, characterized in that, for the supply of the printed sheets (1, 1', 1"), the apparatus (2, 2'. 2", 2"') has a first feed direction (26) extending substantially perpendicular to the rotational axes (6) of the folding rollers (5) or a second feed direction (26') extending substantially parallel to the rotational axes (6) of the folding rollers (5).
4. An apparatus according to Claim 3, characterized in that the compressed-air device (10) has at least two segments (32, 32', 32"), disposed side by side in the first feed direction (26) or one behind the other in the second feed direction (26'), each having at least one outlet (11, 11', 11") provided with a cross-sectional area (19) and each segment (32, 32', 32") being connected to the compressed-air source (14) and to the control unit (16) and including at least one control element (17, 18, 20; 17', 17", 20') and being designed in such a way that it can be activated separately with compressed air (12).
5. An apparatus according to Claim 4, characterized in that the segments (32, 32', 32") each include at least one first control element (17) for varying the duration of the supply of compressed air (12) to the at least one outlet 11, 11', 11") and/or at least one second control element (18) for varying the cross-sectional area (19) of said outlet (11, 11', 11") and/or at least one third control element (20) for varying the pressure of the compressed air (12) supplied to said outlet (11, 11', 11 ").
6. An apparatus according to one of Claims 1 to 5, characterized in that at least one first guide element (21) for the printed sheet (1, 1', 1") is disposed substantially in the guide plane (3), and at least one second guide element (23) for the printed sheet (1, 1', 1") is disposed between the at least one first guide element (21) and the compressed-air device (10), the second guide element (23) extending directly into the region of the outlets (11, 11', 11 ") of the compressed-air device (10).
7. An apparatus according to one of Claims 3 to 6, characterized in that at least a first and a second folding position (33', 33") are formed in the guide plane (3), these being arranged one behind the other in the second feed direction (26') and disposed a distance apart from one another, in which case, located downstream of the folding rollers (5), there are at least two delivery sections (28', 28"), a first delivery section (28') being designed to receive at least one printed sheet (1') made available in the first folding position (33') and a second delivery section (28") being designed to receive at least one printed sheet (1") made available in the second folding position (33").
8. An apparatus according to one of Claims 3 to 6, characterized in that at least a first and a second folding position (36', 36") are formed in the guide plane (3), these being disposed one behind the other in the second feed direction (26') in such a way as to overlap one another, in which case, located downstream of the folding rollers (5), there is a shared delivery section (37) designed 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"), said printed sheets overlapping one another in the second feed direction (26').
9. An apparatus according to one of Claims 3 to 8, characterized in that at least one first and at least one second limit stop (35', 35") are provided in the guide plane (3), the second limit stop (35") being provided upstream of the first limit stop (35') in the second feed direction (26') and both limit stops (35', 35") being formed so that they can be raised above the guide plane (3) and/or lowered below the guide plane (3).
10. An apparatus according to one of Claims 1 to 9, characterized in that the compressed-air device (10) has an alignment plane (39), extending parallel to, and at a distance from, the guide plane (3), and said compressed-air device (10) is designed to be displaceable and/or capable of swivelling in said alignment plane (39).
11. A method of folding printed sheets, in which

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

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

    • in the region of the folding gap (7), from a second side (9) of the guide plane (3) located opposite the first side (4), a blast of compressed air (12') is released from at least one outlet (11, 11', 11") of a compressed-air device (10) connected to a compressed-air source (14) and to a control unit (16) and is directed at the printed sheet (1, 1', 1") made available in the folding position (33, 33', 33", 36', 36"), and the printed sheet (1, 1', 1"), under the effect of the blast of compressed air (12'), is conveyed from the guide plane (3) to the rotating folding rollers (5),
    characterized in that the duration of the supply of compressed air (12) to the at least one outlet (11, 11', 11") of the compressed-air device (10) and/or the cross-sectional area (19) of said outlet (11, 11', 11") and/or the pressure of the compressed air (12) delivered to said outlet (11, 11', 11") are/is adapted to the properties of the available printed sheets (1, 1', 1") and is varied accordingly by means of the control unit (16).
12. A method according to Claim 11, characterized in that the compressed-air device (10) has at least two first outlets (11') having cross-sectional areas (19') of equal size and at least two second outlets (11") having cross-sectional areas (19") of equal size, the cross-sectional areas (19') of the first outlets (11') preferably differing in size from the cross-sectional areas (19") of the second outlets (11"), with at least one control element (17') and at least one other control element (17") for varying the duration of the supply of compressed air (12) to the outlets (11', 11") and for varying the cross-sectional areas (19', 19") of the outlets (11', 11"), in which case the duration of the supply of compressed air (12) to the first and second outlets (11', 11") and the cross-sectional areas (19', 19") of said outlets (11', 11") respectively are varied in that the first outlets (11'), are acted on by one control element (17') and the second outlets (11") are acted on by the other control element (17"), and in addition the pressure of the compressed air (12) supplied to the outlets (11', 11") is optionally varied by means of at least one additional control element (20') connected to said outlets (11', 11 ").
13. A method according to Claim 11 or 12, characterized in that the printed sheet (1, 1', 1") is made available in a first feed direction (26) extending substantially perpendicular to the rotational axes (6) of the folding rollers (5) or in a second feed direction (26') extending substantially parallel to the rotational axes (6) of the folding rollers (5).
14. A method according to Claim 13, characterized in that the compressed-air device (10) has at least two segments (32, 32', 32"), which are disposed side by side in the first feed direction (26) or one behind the other in the second feed direction (26'), each segment (32, 32', 32") having at least one outlet (11, 11'. 11") which is provided with a cross-sectional area (19) and is activated separately with compressed air (12), the control unit (16) triggering a blast of compressed air (12'), modified according to the properties of the available printed sheet (1, 1', 1"), from the at least one outlet (11, 11', 11") of at least one of the segments (32, 32', 32") of the compressed-air device (10) onto the provided printed sheet (1, 1', 1").
15. A method according to Claim 13 or 14, characterized in that, in order to compensate for a printed sheet (1, 1', 1") made available in the guide plane (3) but displaced and/or skewed relative to the feed direction (26, 26'), the compressed-air device (10) is displaced and/or swivelled parallel to the guide plane (3) as appropriate.
16. A method according to one of Claims 13 to 15, characterized in that the printed sheet (1, 1', 1") is made available in one of at least two folding positions (33', 33") disposed one behind the other in the second feed direction (26'), the actual folding position (33', 33") being selected in accordance with a given production order and the blast of compressed air (12') being directed only at the printed sheet (1, 1', 1") made available in said folding position (33', 33"), and, after the folding process, the printed sheet (1, 1', 1") is received by one of at least two delivery sections (28', 28").
17. A method according to one of Claims 13 to 15, characterized in that at least two successive printed sheets (1', 1") are provided a distance apart from one another, each in a different one of at least two folding positions (33', 33") disposed one behind the other in the second feed direction (26'), the actual folding position (33', 33") being selected in accordance with a given production order and the blast of compressed air (12') in each case being directed only at printed sheets (1', 1") placed in said folding position (33', 33") and, after the folding process, the printed sheets (1', 1") are respectively received by a different one of at least two delivery sections (28', 28").
18. A method according to one of Claims 13 to 15, characterized in that at least two successive printed sheets (1', 1"), are each made available in a different one of at least two folding positions (36', 36") disposed one behind the other in the second feed direction (26') and overlapping one another, the actual folding position (36', 36") being selected in accordance with a given production order and the blast of compressed air (12') in each case being directed only at printed sheets (1', 1") placed in said folding position (36', 36") and then, after the folding process, the printed sheets (1', 1") are received, overlapping one another, by a shared delivery section (37).
19. A method according to one of Claims 11 to 18, characterized in that, after the blast of compressed air (12'), at least a second blast of compressed air (12") is directed at the same printed sheets (1, 1', 1"), pressure and/or duration of the second blast of compressed air (12") preferably differing from the first blast of compressed air (12').
20. A method according to one of Claims 11 to 19, characterized in that the blast of compressed air (12') for an available printed sheet (1, 1', 1") is suppressed and said printed sheet (1, 1', 1") is ejected in the guide plane (3).

Images