EP3597430A1 - Device and method for selectively cross folding of sequentially printed sheets - Google Patents

Abstract

The invention relates to a device and a method for optional transverse folding of successive, sequentially printed printed sheets (2, 3). The compressed air device (17) of the device (1) has a first control element (24) connected to the control unit (23) for triggering or suppressing a compressed air blast (19 ') from the at least one outlet opening (18) of the compressed air device (17). A printing sheet can thus be introduced either for folding into the second transport path (28) or for avoiding the folding into the third transport path (32). The latter opens downstream of the folding rollers (12) at a common, second route point (29) into the second transport route (28), a fourth transport route (36) connecting downstream. The third transport path (32) is longer than the second transport path (28) or can be operated more slowly than the second transport path (28), so that a first sequence of the printed sheets successive on the first transport path (5) is equal to a second sequence of those on the fourth transport path (36) is consecutive printed sheets.

Description

The invention relates to an apparatus and a method for optional cross folding of successive, sequentially printed printed sheets. Here, optional cross-folding means that the printed sheets to be processed one after the other are either cross-folded or not cross-folded. The device has a first transport path, on which printed sheets transported in succession in a guide plane can each be provided in a folding position. In addition, the device has at least two folding rollers which are arranged on a first side of the guide plane and each have an axis of rotation and form a folding gap between them for first printing sheets to be folded transversely, the axes of rotation of which are oriented essentially parallel to one another and essentially parallel to the guide plane. Furthermore, the device is equipped with a compressed air device which is aligned essentially parallel to the axes of rotation of the folding rollers, is arranged on a second side of the guide level opposite the first side of the guide level and in the region of the fold gap. The latter is connected to a compressed air source and to a control unit and has at least one outlet opening for compressed air directed towards the folding nip. Finally, the device has a second transport path for folded first printed sheets and a third transport path for unfolded second printed sheets. The first, second and third transport route have a common, first route point at which the first transport route ends and both the second and the third transport route begin. The common, first route point lies on a line of intersection of the guide plane and a fold plane running through the fold gap and the at least one outlet opening of the compressed air device.

In the method, at least a first and a second printed sheet are conveyed in succession in a guide level of a first transport route and in a folding position provided. The first printed sheet provided is folded on a first folding line on a first side of the guide plane in a folding nip between at least two rotating folding rollers each having an axis of rotation. Before the transverse folding, from a second side of the guide plane opposite the first side, a compressed air blast directed in the region of the folding gap at the first printed sheet provided in the folding position is triggered from at least one outlet opening of a compressed air device connected to a compressed air source and to a control unit, and the provided first Printed sheets are transported under the action of the compressed air blast out of the guide level on a second transport path to the rotating folding rollers and, after the cross folding, transported further on this second transport path. In addition, a blast of compressed air is suppressed onto the second printed sheet provided in the folding position and the second unfolded sheet, which has thus not been folded, is introduced into a third transport path.

The sequentially printed printed sheets can be unfolded and / or longitudinally folded printed sheets, which are fed inline, that is to say directly or indirectly afterwards on a digital printing machine. Alternatively, the feed is also possible offline, i.e. starting from an intermediate, sequentially printed material web, from which printed sheets are subsequently separated and then optionally longitudinally folded or also from an intermediate store with unfolded and / or longitudinally folded printed sheets.

With digital printing, the print image is transferred directly from a computer to the printing press without the use of static printing forms. Depending on the folding scheme provided, the material web can be printed in the specified sequence of the finished printed product, ie sequentially. In this way, relatively small quantities up to a single printed product can be realized. In contrast to conventional printing processes, such as offset printing, there are very often successive printed sheets with different properties, such as the print itself, the number of printed pages per printed sheet and its respective format.

After all, digital printing machines nowadays print ever larger quantities of printing material per unit of time. Regardless of whether these are digital printing machines that process material webs or individual printing sheets, these large quantities of printing material must then be processed further. Due to the large material throughput, there are high transport speeds, which make gentle further processing of the printed sheets difficult. Depending on the devices used for further processing, gaps have to be formed between the printed sheets, which additionally increases the transport speed. In addition, blank pages in a print product are less and less accepted today due to the technical possibilities of digital printing.

From the EP2727868 A1 and the EP2727869 A1 A device and a method for longitudinal or transverse folding using a digital printing press sequentially printed sheets are known. The device in each case has a compressed air device connected to a compressed air source and a control unit, with at least one outlet opening for compressed air. A compressed air blast of the compressed air device that conveys the printing sheet from a feed plane between the folding rollers can be dosed simply and quickly according to the properties of a printing sheet that is currently to be folded, so that both a good folding quality and a high folding performance can be achieved across the entire spectrum. In the case of a print sheet that does not meet the quality requirements, the compressed air blast can optionally be suppressed. Thereupon this sheet is not fed to the folding rollers, therefore it is not folded and discharged on a separate conveying path.

With such a device, the transport speed of a printing sheet which has meanwhile been separated from the material web or else of a printing sheet individually printed in the digital printing press can be reduced by one or more transverse folds. For this purpose, the gap between successive printed sheets created during cross folding can be reduced. The gap is also enlarged by removing defective printed sheets.

This device thus only allows the production of a product stream of folded printed sheets. Although cross folding facilitates gentle further processing of the printed sheets on the one hand, with the same number of folds, however, it potentially leads to an undesirable, larger number of blank pages. In contrast, it is known to reduce the number of blank pages in a printed product by integrating unfolded printed sheets. However, neither the known device nor the known method are able to integrate unfolded printed sheets into the product stream. In addition, the use of unfolded printed sheets increases the number of cycles, which, depending on the processing devices used, results in a high transport speed and in turn complicates gentle processing and can lead to quality problems.

With the EP2818331 A2 A device and a method for further processing a paper web sequentially printed by a digital printing press are known. The printed paper web first passes through a perforating and cutting station. The printed sheets separated there are folded one or more times each with transverse and longitudinal folding devices. After folding, the printed sheets that later form a common partial book block are combined in a collating manner in a collating device before they are stacked and glued to a partial book block in a subsequent stacking device. The sub-book blocks are then transported for further processing. To reduce the number of blank pages, the folded sheets can also be combined with an unfolded sheet. However, this unfolded printed sheet must always be fed in at the end of a printed product to be formed, ie after the folded printed sheet. The pocket folding unit usually used in this case absolutely requires a gap between a folded and an unfolded printed sheet for actuating a mechanical flap which, instead of being folded into the folding pocket, deflects a single printed sheet unfolded through the folding rollers. Switching this flap takes a certain amount of time, ie depending on the transport speed a corresponding gap. Such a gap can be created, for example, by a stop and go operation. This gap is the greater, the greater the transport speed and the smaller the section length of the printed sheet and consequently the higher the number of cycles. The time required to switch the flap can be minimized by using the latest drive technology, but it cannot be eliminated.

With such a solution, a certain reduction in the number of blank pages can be achieved due to an optimization of folding patterns which takes place automatically in the machine control system in accordance with the respective production orders, depending on the number of sheets. However, due to the number of processing stations, the costs, the space requirement and the control and regulation outlay are relatively high. Depending on the mode of operation, the transport speed of the printed sheets to be transported through the device individually and at a very short distance after the separation is also relatively high, so that quality problems can arise during their further processing. In addition, the paper web is briefly stopped in the cross cutter upstream of a pocket folder used for cross folding, which leads to discontinuous operation and to the use of a relatively complex, upstream storage section. Finally, the transport path is not cleared until the previous printed sheet has been fed out of the pocket folder again after folding.

Alternatively, a gap can also be formed by increasing the transport speed of the preceding printed sheets or the subsequent units or by slowing down the material web to be fed. However, increasing the transport speeds of the subsequent processes for forming the gap has physical limitations in the known folding machines with pocket folding units, which have a negative effect on the output, so that such folding machines are rather unsuitable for processing large quantities. Generally, accelerating or decelerating compared to constant speed can lead to print quality problems.

From the DE102016203043 A1 a folding machine is known to which the printed sheets are fed in a scaled manner to increase the output, with which a reduction in the transport speed or an increase in the number of printed sheets can be achieved at the same transport speed. This also results in a more flexible solution, which is, however, ultimately very limited when processing large quantities per unit of time. However, due to the above dependency, this method is also not suitable for dynamically processing individual printed sheets. In addition, the different folding roller spacing required depending on the feed of individual printing sheets or a shingled stream would have to be changed with high dynamics, which further complicates process control.

The object of the invention was therefore to create a flexible device and a corresponding method which enable the production of a printed product consisting of cross-folded first and unfolded second printed sheets. The device and the method are intended to allow simple and inexpensive adaptation to changed properties of successive printed sheets with a high folding quality and folding output and are therefore also suitable for further processing of printed sheets printed sequentially by means of digital printing machines. In addition, a potential reduction in the number of blank pages in the finished printed product is to be achieved.

This object is achieved in a device according to the invention for optional transverse folding of successive, sequentially printed printed sheets in that the compressed air device has a first control element connected to the control unit for selectively triggering or suppressing a compressed air blast from the at least one outlet opening of the compressed air device, in such a way that in each case starting from the folding position, a first printed sheet for transverse folding into the second transport path or a second printed sheet for avoiding the transverse folding into the third transport path can be introduced. The third transport route flows into the second transport route downstream of the folding rollers at a common, second route point. Furthermore, a fourth transport route connects downstream of the common, second route point. In addition is the third transport route is longer than the second transport route or can be operated more slowly than the second transport route, such that a first sequence of the printed sheets following one another on the first transport route is equal to a second sequence of the printing sheets following one another on the fourth transport route.

In the method according to the invention, this object is achieved in that the unfolded second printed sheet introduced into the third transport route is conveyed longer on the third transport route than the folded first printed sheet conveyed on the second transport route and the unfolded second printed sheet after the folded first printed sheet in such a way a fourth transport path adjoining the second transport path is initiated such that the sequence of the printed sheets following one another on the first transport path is restored.

In such a device and in the corresponding method, printed sheets sequentially printed by means of digital printing machines can be further processed either cross-folded or unfolded, so that the production of a printed product consisting of cross-folded first and unfolded second printed sheets and thus also a reduction in the number of blank pages in the finished printed product enables becomes. The unfolded second printed sheet can be inserted into the gap after the transverse folded first printed sheet and at a distance therefrom while maintaining or restoring the original sequence into the gap created by circumventing the transverse folding. In addition to triggering or suppressing a blast of compressed air, the first control element can also be used to change the length of time for which compressed air is provided in a folding position. Since the printed sheets can be fed to the device almost without gaps, advantageously no or almost no increase in the transport speed is necessary.

According to one embodiment of the device according to the invention, the third transport path is substantially longer than the second transport path by half an arc length of a first printing sheet to be folded transversely.

The unfolded second printed sheet can thus be inserted at a defined position after the folded first printed sheet and thus advantageously also centrally between two cross-folded first printed sheets. There are no abrupt or substantial changes in the speed of the printed sheets, so that the process stability and / or the quality-impairing influences on the printed sheets can be avoided.

According to a further embodiment of the device according to the invention, a device for adjusting its length is arranged in the region of the third transport route. According to a corresponding embodiment of the method according to the invention, the third transport route has a length which is changed accordingly in a subsequent work order with printed sheets which have at least a different format than the previous work order. This means that both the device and the method can advantageously be adapted to different lengths of the printed sheets of successive work orders.

In a next embodiment of the device according to the invention, a light barrier and / or an image-capturing device for detecting a front edge of a printed sheet transported on the first transport path is arranged in the region of the first transport path and connected to the control unit. According to a corresponding embodiment of the method according to the invention, a front edge of a printed sheet transported on the first transport path is automatically detected. Based on this, corresponding information is forwarded to the control unit. The control unit generates a corresponding pulse at the time of the optional triggering or suppression of a compressed air blast from the at least one outlet opening of the compressed air device onto the printed sheet which has in the meantime been provided in the folding position and forwards this pulse to a first control element connected to the compressed air source and the compressed air device. Due to the arrangement of the light barrier and / or the image capturing device in the area of the first transport route and thus shortly before the compressed air device, the point in time at which the compressed air pulse is triggered or suppressed can be advantageous can be controlled very precisely. The decision as to whether such a blast of compressed air is triggered or suppressed depends on the work orders stored in the control unit. If, in addition or as an alternative to the at least one light barrier, an image-capturing device is arranged, the printed sheets can advantageously be clearly identified directly in front of the cross-folding device using corresponding identification features.

According to a further embodiment of the device according to the invention, a first discharge switch is arranged in the second transport path and a first receiving container for first printed sheets is arranged downstream of the first discharge switch. According to a corresponding embodiment of the method according to the invention, the first printed sheet is discharged from the second transport path for control purposes. The operator can therefore remove a folded first printed sheet located on the second transport path for control purposes at any time.

According to a next embodiment of the device according to the invention, the folding rollers are arranged above and the compressed air device below the guide level. For this reason, the machine operator, for control purposes, can remove a first printed sheet located on the second transport route at an ergonomically favorable working height.

According to a further embodiment of the device according to the invention, a second discharge switch is arranged in the fourth transport path and a second receptacle for printed sheets is arranged downstream of the second discharge switch. According to a corresponding embodiment of the method according to the invention, faulty first and / or second printed sheets are removed from the fourth transport path. In this way, unprinted printed sheets that arise at the beginning or end of a work order can also be rejected.

According to a next embodiment of the device according to the invention, the first, the second, the third and the fourth transport route have a common drive which is connected to the control unit. As a result, there is no additional regulation and control effort with appropriate sensors and monitoring, which is why this solution is inexpensive. Due to the common drive, there are no additional accelerations and decelerations of the printed sheets, so that corresponding quality-reducing effects can be avoided.

According to a further embodiment of the device according to the invention, a fifth transport route begins downstream of the fourth transport route and at a distance therefrom, which has a separate drive connected to the control unit, with which the fifth transport route at a different speed than the fourth transport route and in particular more slowly than the fourth transport route is operable. According to a corresponding embodiment of the method according to the invention, the printed sheets are transferred downstream of the fourth transport route to a fifth transport route which is driven separately from it and is spaced apart from it, on which the printed sheets travel at a different speed than on the fourth transport route and in particular more slowly than on the fourth Transport route are promoted. Because the speed of the fifth transport route differs from the speed of the fourth transport route, the latter can advantageously be adapted to the needs of the subsequent further processing. If the fifth transport route is operated more slowly than the fourth transport route, the gaps between the successive printed sheets in the device can be minimized to a desired extent.

In a next embodiment of the device according to the invention, the fourth transport route and / or the fifth transport route has an adjusting element for adjusting a distance between these two transport routes. According to a corresponding embodiment of the method according to the invention, in a subsequent work order in which at least one printed sheet is of a different format than the printed sheet of the previous one Work order has, a distance between the fourth transport route and the fifth transport route changed accordingly. With a device or the corresponding method designed in this way, it can be adapted to successive work orders with printed sheets of different lengths, so that in the case of a subsequent work order, a printed sheet at the transition from the fourth to the fifth transport route with a larger format is not clamped simultaneously on both transport routes and thereby being crushed, crumpled or even destroyed. On the other hand, even in the case of a subsequent work order, a printed sheet with a smaller format at the transition from the fourth to the fifth transport route should be able to be safely transferred from the fifth transport route.

According to a further embodiment of the device according to the invention, it has at least one further control element connected to the compressed air source and the control unit for changing a cross-sectional area of the at least one outlet opening of the compressed air device and / or for changing a pressure of the compressed air that can be supplied to this outlet opening. By appropriately loading at least one of the two further control elements, the compressed air blast of the compressed air device can be dosed simply and quickly according to the properties of a first printed sheet which is currently provided in the folding position and is to be folded transversely and a good folding quality as well as one over the entire spectrum of the first printing sheet to be folded transversely high folding performance can be achieved.

According to a next embodiment of the method according to the invention, a first partial gap is generated in the second transport path when forwarding an unfolded second printed sheet into the third transport path, upstream of a folded first printed sheet. During the folding process of a further first printed sheet belonging to the same work order, a second partial gap is generated downstream of this further first printed sheet and adjacent to the first partial gap. Both partial gaps together form a feed-in gap into which the unfolded second printed sheet conveyed on the third transport route is introduced again in the area of the fourth transport route between the folded first printed sheet and the further, folded first printed sheet. In this way, a feed-in gap is created in the second transport route in a simple manner and this is used in the area of the fourth transport route for inserting the unfolded second printing sheet which bypasses the folding rollers and is conveyed on the third transport route between the two folded first printing sheets belonging to the same work order.

According to a further embodiment of the method according to the invention, a first printed sheet with a first sheet length, a second printed sheet with a second sheet length and a further first printed sheet with a first sheet length are provided in succession in the folding position, with the first sheet length essentially being double for printed sheets of the same work order is as large as the second arc length. In this way it is ensured that the first printed sheets after folding have essentially the same sheet length as the associated unfolded second printed sheet, so that the latter can be easily inserted into the insertion gap between two successive first printed sheets in the region of the fourth transport path.

Fig. 1

Eine schematische Seitenansicht einer erfindungsgemässen Vorrichtung zum wahlweisen Querfalzen aufeinander folgender, sequenziell bedruckter Druckbogen, in einem ersten Ausführungsbeispiel.

Fig. 2

Eine vergrösserte schematische Darstellung einer Querfalzeinrichtung der erfindungsgemässen Vorrichtung, dargestellt zu einem etwas früheren Zeitpunkt als bei der Fig. 1.

Fig. 3

Eine schematische Draufsicht auf die Querfalzeinrichtung nach Fig. 1 und 2, wobei sich in der Querfalzeinrichtung, d.h. zwischen deren Falzwalzen und der Drucklufteinrichtung, ein erster Druckbogen in einer Falzposition befindet.

Fig. 4

Eine schematische Seitenansicht der Vorrichtung nach Fig. 1, wobei jedoch sämtliche Druckbogen gefalzt worden sind bzw. gefalzt werden.

Fig. 5

Eine erste Momentaufnahme der Vorrichtung nach Fig. 1, wobei sämtliche zur Weiterverarbeitung, d.h. beispielsweise zur späteren Bildung von Teilbuchblocks vorgesehenen Druckbogen die Falzwalzen umgehen und somit nicht gefalzt werden.

Fig. 6

Eine zweite, gegenüber der Fig. 5 spätere Momentaufnahme der Vorrichtung nach Fig. 1.

Fig. 7

Eine vergrösserte schematische Darstellung des in Fig. 1 dargestellten stromabwärtigen Bereichs der Vorrichtung, in einem zweiten Ausführungsbeispiel mit einer zusätzlichen, fünften Transportstrecke.

Fig. 8

Eine Darstellung wie in Fig. 7, jedoch zu einem etwas späteren Verfahrenszeitpunkt.

The invention is described in more detail below on the basis of exemplary embodiments. Show:

Fig. 1

A schematic side view of a device according to the invention for optional transverse folding of successive, sequentially printed printed sheets, in a first embodiment.

Fig. 2

An enlarged schematic representation of a transverse folding device of the device according to the invention, shown at a slightly earlier point in time than in the Fig. 1 ,

Fig. 3

A schematic plan view of the cross folding device according to Fig. 1 and 2 , wherein in the transverse folding device, ie between its folding rollers and the compressed air device, a first printed sheet is in a folding position.

Fig. 4

A schematic side view of the device according to Fig. 1 , in which however, all of the printed sheets have been or are being folded.

Fig. 5

A first snapshot of the device after Fig. 1 , whereby all of the printed sheets provided for further processing, for example for the later formation of partial book blocks, bypass the folding rollers and are therefore not folded.

Fig. 6

A second, opposite the Fig. 5 later snapshot of the device after Fig. 1 ,

Fig. 7

An enlarged schematic representation of the in Fig. 1 shown downstream region of the device, in a second embodiment with an additional, fifth transport route.

Fig. 8

A representation like in Fig. 7 , but at a later stage in the proceedings.

Fig. 1 shows in a first embodiment a schematic side view of a device 1 according to the invention for optional transverse folding of printed sheets 2, 3, ie here the illustrated printed sheets 3a, 2a "; 2b ', 3b, 2b"; 2c ', 3c, 2c ", 2d', which were previously printed sequentially by a digital printing machine, not shown, and which downstream of the device 1 each form a partial book block 4a, 4b, 4c, 4d, etc. indicated in different figures by means of a curly bracket. According to the illustration, first printed sheets 2a ", 2b ', 2b", 2c' have already been folded in device 1, while a next first printed sheet 2c "is being folded and another first printed sheet 2d 'in a next method step is to be folded. Second printed sheets 3, here for example printed sheets 3a, 3b, 3c, are transported unfolded by device 1. The printed sheets 3a, 2a "and a leading, not shown printed sheet 2a 'are for later production of the first partial book block 4a, the printed sheets 2b', 3b, 2b" for the subsequent production of the second partial book block 4b and the printed sheets 2c ', 3c, 2c " for a third, in Fig. 7 and in Fig. 8 also provided with a curly bracket later sub-book block 4c. Furthermore, printed sheets 2, 3 that have been removed from the device 1, used for control purposes or faulty, ie the printed sheets 2x, 3y and 2z, are shown here. Although in this illustration In each case three printed sheets are provided to form a partial book block, such a sheet can of course also be formed by a different number of printed sheets. In addition, instead of discharging a single printed sheet 2, 3, a whole number of printed sheets can also be discharged one after the other.

A cutting and perforating unit, also not shown, is arranged upstream of the device 1 according to the invention. A first transport section 5 belonging to the device 1 is connected to the cutting and perforating unit and is connected to a transverse folding device 6 of the device 1. At least one light barrier 7 and / or an image-capturing device 8 is arranged in the region of the first transport path 5 and immediately in front of the cross-folding device 6.

The Fig. 2 shows an enlarged schematic representation of the transverse folding device 6 of the device 1 according to the invention, in which, in contrast to Fig. 1 however, the folding of the first printing sheet 2c "has only just begun. The first transport path 5 has a guide plane 9, into which a next printing sheet 2, 3, here the next first printing sheet 2d 'to be folded transversely, is fed and ends in the transverse folding device 6 at a first route point 10, from which the first printed sheet 2c "has currently been forwarded for transverse folding.

The guide plane 9 shown here running horizontally can, of course, also be arranged vertically or at any angle in space, which, depending on the specific conditions of use, enables a large number of structural options. Although only a single printed sheet 2, 3 has been described and shown in the figures so far and also below for reasons of simplification, this is, however, in each case at least one printed sheet 2, 3, i.e. either actually around a single or several superimposed printed sheets 2, 3.

Two folding rollers 12 are arranged on a first side 11 of the transverse folding device 6 located above the guide plane 9. These each have one Axis of rotation 13 and form between them a fold gap 14 for the on a prepared fold line 15 ( Fig. 3 ) or on an unprepared fold line transverse to the first printed sheet 2 to be folded. The axes of rotation 13 of the folding rollers 12 are aligned both essentially parallel to one another and essentially parallel to the guide plane 9. Based on previously known order data or on currently recorded data, the folding nip 14 can be adjusted manually or advantageously also by motor, depending on the material thickness and number of the first printed sheets 2 to be folded transversely. The diameters of the two folding rollers 12 can be of the same or different design. For example, in order to prevent the printing sheet from touching the downstream folding roller 12 and thus preventing the printing sheet from braking, the diameter of the downstream folding roller 12 can be made smaller than the diameter of the upstream folding roller 12.

A compressed air device 17 of the transverse folding device 6 is arranged on a second side 16 of the transverse folding device 6 opposite the first side 11 of the guide plane 9 and thus below the guide plane 9. The compressed air device 17, which is oriented essentially parallel to the axes of rotation 13 of the folding rollers 12, has at least one, but preferably a plurality of outlet openings 18 directed towards the folding gap 14 ( Fig. 2 . Fig. 3 ) for compressed air 19 and is connected via a compressed air line 20 to a compressed air source 21 and this in turn via a control line 22 to a control unit 23 of the device 1. In addition, the compressed air device 17 has, for example, a first control element 24, designed as a solenoid valve, for acting on one in a Fig. 3 folding position 25 shown first printing sheet 2, here the first printing sheet 2c ", with compressed air 19, in which folding position 25 the first printing sheet 2 lies stretched flat between the folding rollers 12 and the compressed air device 17, or also for changing the duration of the application of the at least one Outlet opening 18 with compressed air 19.

In Fig. 3 Also shown are the printed sheets 2d ', 3d, 2d "belonging to a partial book block 4d that can be produced downstream of the device 1, which like the other first printed sheets 2 each have a first sheet length 2" or like the other second printed sheets 3 each have a second sheet length 3 ". The sheet lengths 2", 3 "of related sheets 2, 3 differ in such a way that the first sheet length 2" is essentially twice as large as the second sheet length 3 ". Although except in Fig. 3 also in the Figures 1 . 2 . 7 and 8th it is shown that an unfolded second printed sheet 3 is inserted between two transversely folded first printed sheets 2 or is provided there for insertion, the device 1 can, of course, in principle produce any order of transversely folded first printed sheets 2 and unfolded second printed sheets 3.

Furthermore, the compressed air device 17 can have a second control element 26, which is designed here, for example, as a slide, for changing a cross-sectional area (not shown) of the at least one outlet opening 18, and a third control element 27, which is arranged, for example, as a pressure reducing valve and is arranged in the compressed air line 20, for changing a pressure of the at least one Compressed air 19 that can be supplied with outlet opening 18 ( Fig. 2 ). In this case, the second control element 26 can be connected, for example, to a diaphragm which is also not shown, can be moved and has at least one recess. By moving this diaphragm accordingly, the at least one outlet opening 18 is partially or completely opened or completely covered, ie its cross-sectional area is changed. Of course, this cross-sectional area can also be changed using other suitable means. The control elements 24, 26, 27 are each connected to the control unit 23 via a control line 22.

A second transport route 28 for transversely folded first printed sheets 2 begins at the first route point 10 and leads between the folding rollers 12 of the transverse folding device 6 to a second route point 29. Along the second transport route 28 a first discharge switch 30 is arranged with which a transversely folded first printed sheet is arranged 2x can be fed to a first receiving container 31, for example, designed to take specimens ( Fig. 1 ).

A third transport route 32 for unfolded second printed sheets 3, likewise beginning at the first route point 10, adjoins the first transport route 5. The first route point 10 is thus a common route point of the first transportation route 5 ending there and the second and third transportation routes 28 and 32 starting there. The third transportation route 32 meets the second transportation route 28 at the second route point 29 and ends there. It has a length that is greater than the length of the second transport path 28. In addition, the third transport path 32 has a device 33 for length adjustment, which is as in FIG Fig. 1 shown, for example, has a sliding cylinder 33a with a cylinder rod 33b and a roller 33c attached to it and interacting with the third transport path 32. Of course, another suitable device can also be used to adjust the length of the third transport path 32. The first route point 10 lies on a section line 34 of the guide plane 9 and a fold plane 35 running through the fold gap 14 and the at least one outlet opening 18 of the compressed air device 17 ( Fig. 2 . Fig. 3 ).

A fourth transport route 36 adjoins the second and third transport routes 28, 32 at the second route point 29 ( Fig. 1 ). The second route point 29 is thus a common route point of the second, third and fourth transport route 28, 32, and 36. With a second discharge switch 37 arranged along the fourth transport route 36, both transversely folded first printed sheets 2 and unfolded second printed sheets 3, here the Printed sheets 2z and 3y, but also waste and removed and fed to a second receptacle 38. A further light barrier 7 'can be arranged in front of the first and second diverter switch 30, 37 in order to be able to switch the respective diverter switch 30, 37 exactly.

As shown in Fig. 1 the device 1 on the first transport path 5 has been fed several times in succession a first printing sheet 2 to be folded, followed by a second printing sheet 3 not to be folded and this in turn followed by a further first printing sheet 2 to be folded. In the downstream area of the fourth transport route 36 of the device 1, these are the unfolded second printed sheet 3a and the transversely folded first printed sheet 2a ", which are provided together with a leading, not shown, transversely folded first printed sheet 2a 'for the first partial book block 4a. For this purpose, the printed sheets 2a', 3a, 2a "first in this order one after the other on the first transport route 5 up to the folding position 25 ( Fig. 3 ) promoted, in which they lay stretched flat between the folding rollers 12 and the compressed air device 17. Starting from this folding position 25, the first printed sheets 2a ', 2a "to be folded transversely, as in FIG Fig. 2 shown for the first printed sheet 2c ", in each case acted upon by a compressed air blast 19 'from the at least one outlet opening 18 of the compressed air device 17. Due to this compressed air blast 19', the first printed sheets 2a ', 2a" to be folded transversely are between the folding rollers in their central region 12 pressed, redirected to the second transport section 28 and then folded transversely by means of the folding rollers 12. The compressed air pulse 19 ′ is triggered by the transmission of a corresponding control signal from the control unit 23 via the control line 22 to the first control element 24, and compressed air 19 has been provided from the compressed air source 21. In contrast, such a blast of compressed air 19 'was suppressed on the second printed sheet 3a, which is now also in the folding position 25 and is not to be folded, so that the folding rollers 12 were immediately forwarded to the third transport path 32. The decision as to whether such a compressed air pulse 19 ′ is triggered or suppressed depends on the work orders stored in the control unit 23. Since the control unit 23 also knows the number and the sequence of the first printed sheets 2 to be folded transversely and the second printed sheets 3 not to be folded, which are provided for the respective sub-book blocks 4a, 4b, 4c, 4d, etc., according to these work orders, is used immediately before the transverse folding device 6 arranged at least one light barrier 7 and / or image capturing device 8 each determines the exact time for a pulse to trigger or suppress the compressed air blast 19 '. If, in addition or as an alternative to the at least one light barrier 7, an image-capturing device 8 is arranged, the printed sheets 2, 3 can advantageously be uniquely identified directly in front of the cross-folding device 6 by means of corresponding identification features.

As a result of the forwarding of the unfolded second printing sheet 3a to the third transport path 32, a first partial gap 39a has arisen in the second transport path 28, upstream of the first printing sheet 2a ' Fig. 1 is shown in an analogous manner upstream of the first printed sheet 2c 'with a curly bracket. This first partial gap 39a was followed by a second partial gap 39b, which was created downstream of the first printing sheet 2a "by its folding process and which in FIG Fig. 1 is also shown in an analogous manner downstream of the first printing sheet 2c "with a curly bracket. The second partial gap 39b arises in each case because the first printing sheets 2 to be folded transversely before reaching the folding rollers 12 first with their front edge 2 '( Fig. 2 . Fig. 3 ) and penetrate almost to the middle of the sheet into the third transport section 32 before they are finally deflected into the folding rollers 12 by the action of the compressed air blast 19 'on the sheet center and their original sheet length 2 "is thus halved. The two partial gaps 39a, 39b formed a common insertion gap 39 between the two successive first printed sheets 2a ', 2a ", as in FIG Fig. 1 is shown by the corresponding insertion gap 39, also represented by a curly bracket, between the first printed sheet 2c 'currently in the second transport path 28 and the subsequent first printed sheet 2c "which is currently in the folding process. After being transported on the third transport path 32, the unfolded second printed sheet 3a in the area of the second route point 29 was inserted exactly into this insertion gap 39 between the transversely folded first printed sheets 2a ', 2a ". The procedure described above has also been carried out analogously for the printed sheets 2b ', 3b, 3b "provided for the second partial book block 4b, the Fig. 1 shows exactly the situation in which the unfolded second printed sheet 3b has been inserted into the previously existing insertion gap 39 between the two transversely folded first printed sheets 2b 'and 2b ". If, in a subsequent work order, print sheets 2, 3 with at least one compared to the previous work order different format are processed, the third transport path 32 can be lengthened or shortened with the device 33 for length adjustment such that the unfolded second printed sheet 3, which is respectively conveyed on this transport route 32, advantageously also centrally in the insertion gap 39 between the associated, transversely folded first printed sheets 2 is insertable.

The printed sheets 2, 3 are transported on all transport routes 5, 28, 32, 36 with in Fig. 3 shown, arranged on both sides of the printed sheets 2, 3, for example designed as a conveyor belt or conveyor belts 40, 40 '. Due to the in the representation of the Fig. 3 The conveying elements 40, 40 'are only shown horizontally running, the conveying elements 40, 40' are arranged there both below and above the printed sheets 2, 3 to be transported. In the case of vertical or also inclined transport routes, as is the case, for example, in the upstream region of the second transport route 28 and in the downstream region of the third transport route 32, the conveying elements 40, 40 'can be arranged laterally. In Fig. 3 For the sake of simplicity, the lower conveyor elements 40 'were only shown in the third transport route 32. Similar conveyor elements 40, 40 'are also shown in Fig. 7 and in Fig. 8 and partly in Fig. 2 shown. The conveyor elements 40, 40 'of the transport routes 5, 28, 32, 36 are driven at the same speed v _1-4 and have an in Fig. 7 and 8th shown common drive 41. Of course, the transport routes 5, 28, 32, 36 can also have their own drives. In the Fig. 1 and in the 4 to 6 A plurality of deflection and / or tensioning rollers 42 are shown in the third transport path 32 for their conveying elements 40, 40 ', which are not shown in these figures. Similar deflection and / or tensioning rollers for the conveyor elements can of course also be arranged in the second transport path 28.

According to Fig. 4 The device 1 can also be operated in such a way that only first printed sheets 2 to be folded transversely are used. Therefore, unfolded second printed sheets 3 are not discharged via the third transport path 32, ie this remains inactive. Starting from an exemplary order with a sequence of partial book blocks with two, three and a first printed sheet 2 to be folded transversely, in Fig. 4 from left to right the already transversely folded first printed sheets 2a ', 2a ", 2b', 2b", 2b "', a first printed sheet 2c', which was just raised by means of a compressed air blast 19 'in the middle of the sheet from the folding position in the direction of the folding rollers 12, and a further according to a subsequent order across folding first printed sheet 2d 'shown. In this operating mode of the device 1, a compressed air blast 19 'is triggered whenever a first printed sheet 2 is in the folding position 25. Due to the folding process, a first discharge gap 43, which is shown with a curly bracket, also arises between the transversely folded first printing sheets 2, which permits problem-free connection of the two discharge switches 30, 37, so that, if necessary, transversely folded first printing sheets 2 are used for trial purposes or even incorrect ones Specimens like the one in Fig. 4 illustrated, cross-folded first printed sheets 2x, 2z, can be discharged. The first printed sheets 2 which have not been discharged can in turn be further processed downstream of the device 1, for example to sub-book blocks not shown here.

Corresponding Fig. 5 A further operating mode of the device results, in which all the second printed sheets 3 provided for further processing, that is to say, for example, for later formation of partial book blocks, which are also not shown here, ie the printed sheets 3a ', 3a ", 3b', 3b", 3b "'shown , 3c ', 3d', 3d ", 3e ', 3e", bypass the folding rollers 12 and are therefore not folded. For this purpose, in the second printing sheet 3 located in the folding position 25, just as in the illustrated second printing sheet 3e', The compressed air blast 19 'is suppressed, so that the second printed sheets 3 are thus conveyed through the third transport path 32. In this case, the second printed sheets 3 are transported virtually without gaps through the entire device 1. If necessary, however, defective second printed sheets 3 should nevertheless be used can be discharged, as has already been done with the second printed sheet 3z located in the second receptacle 38. For example, to add another sheet still on the dr To remove the second printing sheet 3z located in the transport section 32 via the second discharge switch 37, a first printing sheet located in the folding position 25 leading this second printing sheet 3z was deflected 2x by means of a compressed air blast 19 'in the direction of the folding rollers 12 and thus to the second transport section 28. In this way, in the third transport path 32 and between the leading second printed sheet 3d ″ and the further second printed sheet to be discharged later into the second receptacle 38 3z a second discharge gap 44 has been formed. In Fig. 5 A first snapshot is shown, according to which this second discharge gap 44 in the third transport route 32 has already moved somewhat in the direction of the second route point 29. In Fig. 6 on the other hand, a later snapshot is shown with the beginning discharge of the further second sheet 3z to be discharged, after this has previously been detected on the further light barrier 7 'and the second discharge switch 37 has been switched accordingly. The second discharge gap 44 previously used to switch the second discharge switch 37 is, as shown, already largely downstream of the second discharge switch 37 during this snapshot. Upstream, the further second printed sheets 3e ', 3e ", 3e"', 3f ', 3f ", 3g follow 'and 3g ".

Which according to Fig. 5 First printed sheets 2x located on the second transport path 28 and used to enable the switching of the second discharge switch 37 and thus to remove the further second printed sheet 3z were previously folded transversely between the folding rollers 12. However, since this first printed sheet 2x does not become part of the later partial book blocks and is thus intended to be discharged into the first receptacle 31, it can be folded across at any point. Also, switching the first discharge switch 30 after detecting the first printed sheet 2x with the further light barrier 7 'proves to be unproblematic because the first printed sheet 2x does not immediately precede the first printed sheet 2. Fig. 6 shows the ejected first printed sheet 2x located in the first receptacle 31. By a corresponding earlier triggering of the compressed air blast 19 'on the first printing sheet 2x, ie before reaching its folding position 25, this first printing sheet 2x can also be deflected in the direction of the folding rollers 12 in such a way that it passes through it unfolded and can advantageously be used again later. When starting up or when switching off the device 1 or one of these digital printing machines upstream of this type, such a first printing sheet 2x is part of the waste anyway and is therefore disposed of from the first receptacle 31.

In a second embodiment ( Fig. 7 . Fig. 8 ) the device 1 closes downstream of the fourth transport path 36 there is a fifth transport path 45 spaced from it, on which the printed sheets 2, 3 are fed to a downstream, not shown, device for further processing, for example a device for forming partial book blocks 4a, 4b, 4c, 4d etc. As in Fig. 7 illustrated, the printed sheets 2a "and 2b 'are currently being conveyed on the fifth transport path 45. The fifth transport path 45 also has conveying elements 40, 40', which, however, in comparison to the common drive 41 of the transport paths 5, 28, 32, 36 via a separate one Drive 46. Due to this separate drive 46, the fifth transport route 45 can be operated at a speed v ₅ which differs from the speed v _1-4 the other four transport routes 5, 28, 32, 36.

For example, the speed v _{5 is} chosen to be lower than the speed v _1-4 if existing partial gaps, such as that in FIG Fig. 7 shown partial gap 39b between the two successive transversely folded first printed sheets 2b "and 2c 'are to be minimized. This also applies to the minimization of residual gaps of the former partial gaps 39a, 39b. A first residual gap 39a' is, for example, downstream of the previous one generated gap 39 between the transversely folded first printed sheet 2c 'and 2c ", unfolded second printed sheet 3c and such a forming second residual gap 39b' downstream of the transversely folded first printed sheet 2c". A further second residual gap 39b 'is located downstream Area of the fourth transport route 36. Of course, depending on the further processing downstream of the device 1, the speed v ₅ can also be greater than the speed v _1-4 , for example if in device 1 according to Fig. 5 and Fig. 6 only unfolded second printed sheets 3 are guided over the third transport path 32 and if corresponding gaps between the second printed sheets 3 are required for further processing.

When transferring a printed sheet 2, 3 from the fourth transport route 36 to the fifth transport route 45, as in FIG Fig. 7 of the unfolded second printed sheet 3b, this is first transported by the conveying elements 40, 40 'of the fourth transport path 36 until it no longer passes through at its rear edge this conveyor elements 40, 40 'is clamped. Fig. 7 shows exactly the subsequent moment in which the front edge 3 'of the unfolded second printed sheet 3b is clamped for the first time by the conveying elements 40, 40' of the fifth transport path 45 and thus its transport is taken over by the fifth transport path 45. The fifth transport route 45 thus begins at a third route point 47, at a distance from the fourth transport route 36, at which a printed sheet 2, 3 experiences a conveying impulse from the fifth transport route 45 for the first time Conveying elements 40, 40 'one of the two transport routes 36, 45 is clamped, upsetting, creasing or even destroying this printed sheet 2, 3 can be effectively avoided.

Because the size of a distance 48 existing between the two transport routes 36, 45 is therefore decisive for the correct transfer of the respective printing sheet 2, 3 and because printing sheets 2, 3 of different formats can be processed depending on the production order, at least one of the two transport routes 36, 45, however, both are advantageously provided with an adjusting element 49 for changing this distance 48. The control element or elements 49 can be operated manually or advantageously by motor.

Fig. 8 shows one opposite the Fig. 7 somewhat later snapshot, in which the transversely folded first printed sheet 2b "following the unfolded second printed sheet 3b" has just been released by the conveying elements 40, 40 'of the fourth transport route 36 and at its front edge at the third route point 47 with the conveying elements 40, 40' the fifth transport path 45 has been clamped. The first transversely folded printed sheet 2b "has now been transferred to the fifth transport path 45 and the further transport takes place with its conveying elements 40, 40 '.

Due to the lower speed v _{5 of} the fifth transport route 45 than the speed v _{1-4 of} the transport routes 5, 28, 32, 36, the in Fig. 7 between the printed sheets 3b and 2b "in the downstream region of the fourth Transport route 36 still existing second gap 39b 'in Fig. 8 already been minimized. Since the speed v _{5 of} the first printed sheet 2b 'now being conveyed on the fifth transport route is also lower than the speed of the subsequent printed sheet 2c' still being conveyed on the fourth transport route 36, the second partial gap which has meanwhile been conveyed into the downstream region of the fourth transport route 36 becomes 39b between these first printed sheets 2b ", 2c 'will soon be minimized. Analogously, this later also applies to the two remaining gaps 39a ', 39b' and to all subsequent gaps between the printed sheets.

Triggered by the control device 23, the separate drive 46 can be operated at different speeds, so that successively different speeds v _{5 of} the fifth transport route 45 can be realized. In this way, the remaining gaps between the printed sheets 2, 3 conveyed on the fifth transport path 45 can be given a uniform length if required.

Of course, the connection of the control unit 23 of the device 1 with the control elements 24, 26, 27 of the cross-folding device 6, with the light barriers 7, 7 ', with the image-capturing device 8, with the two, described and shown here in each case as a wire-bound connection Diverter switches 30, 37 and with the drives 41, 46 of the transport routes 5, 28, 32, 36, 45 can also be designed wirelessly. Of course, other sensors, drives or devices, such as device 33 for length adjustment, can also be connected to control unit 23, as shown in FIG Fig. 1 is shown with a dashed line.

Claims (20)

Device for optional cross folding of successive, sequentially printed printed sheets (2, 3) with A first transport path (5), on which printed sheets (2, 3) transported in succession in a guide plane (9) can each be provided in a folding position (25), At least two folding rollers (12) arranged on a first side (11) of the guide plane (9), each having an axis of rotation (13) and forming a folding gap (14) between them for transverse first printing sheets (2) to be folded, the axes of rotation ( 13) are aligned both essentially parallel to one another and essentially parallel to the guide plane (9), An essentially parallel to the axes of rotation (13) of the folding rollers (12), on a second side (16) of the guiding plane (9) opposite the first side (11) of the guiding plane (9) and in the area of the folding gap (14) arranged compressed air device (17) which is connected to a compressed air source (21) and to a control unit (23) and has at least one outlet opening (18) for compressed air (19) directed towards the folding gap (14), • a second transport route (28) for transversely folded first printed sheets (2) and a third transport route (32) for unfolded second printed sheets (3), the first, second and third transport routes (5, 28, 32) being a common, first route point (10) at which the first transport route (5) ends and both the second transport route (28) and the third transport route (32) begin, and the common, first route point (10) on an intersection line (34) of the guide plane ( 9) and a folding plane (35) running through the folding gap (14) and the at least one outlet opening (18) of the compressed air device (17), characterized in that • The compressed air device (17) with the control unit (23) connected to the first control element (24) for optional triggering or suppression of a compressed air blast (19 ') from the at least one outlet opening (18) of the compressed air device (17), such that, starting from the folding position (25), a first printed sheet (2) for folding into the second transport path (28) or a second printed sheet (3) can be introduced into the third transport path (32) in order to avoid folding, The third transport route (32) opens into the second transport route (28) downstream of the folding rollers (12) at a common, second route point (29), • Connects a fourth transport route (36) downstream of the common, second route point (29), and • The third transport path (32) is longer than the second transport path (28) or can be operated more slowly than the second transport path (28), so that a first sequence of the printed sheets (2, 3) following one another on the first transport path (5) is the same a second sequence of the printed sheets (2, 3) following one another on the fourth transport path (36). Device according to claim 1, characterized in that the third transport path (32) is substantially longer than the second transport path (28) by half an arc length (2 ") of a first printing sheet (2) to be folded transversely. Device according to claim 1 or 2, characterized in that a device (33) for adjusting the length of the third transport path (32) is arranged in the region of the third transport path (32). Device according to one of claims 1 to 3, characterized in that in the region of the first transport route (5) a light barrier (7) and / or an image-capturing device (8) for detecting a front edge (2 ', 3') one on the first Transport route (5) transported printed sheet (2, 3) is arranged and connected to the control unit (23). Device according to one of claims 1 to 4, characterized in that that a first discharge switch (30) and downstream of the first discharge switch (30) a first receptacle (31) for first printed sheets (2) is arranged in the second transport path (28). Device according to one of claims 1 to 5, characterized in that the folding rollers (12) are arranged above and the compressed air device (17) below the guide plane (9). Device according to one of claims 1 to 6, characterized in that a second discharge switch (37) and downstream of the second discharge switch (37) a second receptacle (38) for printed sheets (2, 3) is arranged in the fourth transport path (36). Device according to one of claims 1 to 7, characterized in that the first, second, third and fourth transport route (5, 28, 32, 36) have a common drive (41) which is connected to the control unit (23). Device according to one of claims 1 to 8, characterized in that a fifth transport path (45) begins downstream of the fourth transport path (36) and at a distance therefrom , which has a separate drive (46) connected to the control unit (23), with which the fifth transport route (45) can be operated at a different speed than the fourth transport route (36) and in particular more slowly than the fourth transport route (36). Apparatus according to claim 9, characterized in that the fourth transport route (36) and / or the fifth transport route (45) has an adjusting element (49) for adjusting a distance (48) between these two transport routes (36, 45). Device according to claim 1 to 9, characterized in that it at least a further control element (26, 27) connected to the compressed air source (21) and the control unit (23) for changing a cross-sectional area of the at least one outlet opening (18) of the compressed air device (17) and / or for changing a pressure of this outlet opening (18) Compressible air (19) which can be supplied. Method for optional transverse folding of successive, sequentially printed printed sheets (2, 3), in which At least a first printed sheet (2) and a second printed sheet (3) are successively conveyed in a guide plane (9) of a first transport path (5) and provided in a folding position (25), • The first printed sheet (2) provided on a first side (11) of the guide plane (9) in a folding gap (14) between at least two rotating folding rollers (12), each with an axis of rotation (13), on a folding line (15) transversely is folded, • before folding from a second side (16) of the guide plane (9) opposite the first side (11), a compressed air blast directed in the region of the folding gap (14) onto the first printed sheet (2) provided in the folding position (25) ( 19 ') from at least one outlet opening (18) of a compressed air device (17) connected to a compressed air source (21) and to a control unit (23) and the provided first printed sheet (2) under the action of the compressed air blast (19') from the guide level ( 9) transported out on a second transport path (28) to the rotating folding rollers (12) and transported further on this second transport path (28) after folding, A compressed air blast (19 ') is suppressed onto the second printed sheet (3) provided in the folding position (25) and the unfolded second printed sheet (3) is introduced into a third transport path (32), characterized in that • The unfolded second printed sheet (3) introduced into the third transport section (32) is conveyed longer on the third transport section (32) than the transversely folded first printed sheet (2) conveyed on the second transport section (28), and • The unfolded second printed sheet (3) after the transversely folded first printed sheet (2) is introduced into a fourth transport route (36) adjoining the second transport route (28) in such a way that the sequence of the printed sheets following one another on the first transport route (5) (2, 3) is restored. Method according to Claim 12, characterized in that the third transport route (32) has a length which is changed accordingly in a subsequent work order with printed sheets (2, 3) which have at least a different format than the previous work order. Method according to one of claims 12 or 13, characterized in that a leading edge (2 ', 3') of a printed sheet (2, 3) transported on the first transport path (5) is automatically detected based on a corresponding information to the control unit ( 23) is forwarded, the control unit (23) sends a corresponding pulse at the time of the optional triggering or suppression of a compressed air blast (19 ') from the at least one outlet opening (18) of the compressed air device (17) onto the printed sheet which has meanwhile been made available in the folding position (25) (2, 3) is generated and this pulse is forwarded to a first control element (24) connected to the compressed air source (21) and the compressed air device (17). Method according to one of claims 12 to 14, characterized in that first printed sheets (2) are removed from the second transport path (28) for control purposes. Method according to 12 to 15, characterized in that faulty first and / or second printed sheets (2, 3) are removed from the fourth transport path (36). Method according to one of claims 12 to 16, characterized in that the printed sheets (2, 3) downstream of the fourth transport path (36) a fifth transport route (45), which is driven separately and at a distance from the latter, is transferred, on which the printed sheets (2, 3) at a different speed than on the fourth transport route (36) and in particular more slowly than on the fourth transport route (36 ) are promoted. A method according to claim 17, characterized in that in a subsequent work order, in which at least one printed sheet (2, 3) has a different format than the previous work order, there is a distance (48) between the fourth transport route (36) and the fifth transport route ( 45) is changed accordingly. Method according to one of claims 12 to 18, characterized in that in the second transport path (28), when an unfolded second printing sheet (3) is passed into the third transport path (32), upstream of a folded first printing sheet (2), a first partial gap (39a) is generated so that during the folding process of a further first printed sheet (2) belonging to the same work order, downstream of this further first printed sheet (2) and adjacent to the first partial gap (39a), a second partial gap (39b) is generated, so that the two Partial gaps (39a, 39b) together form an insertion gap (39) into which the unfolded second printed sheet (3) conveyed on the third transport route (32) in the area of the fourth transport route (36) again between the folded first printed sheets (2) and the another, folded first printed sheet (2) is introduced. Method according to claim 19, characterized in that in the folding position (25) a first printed sheet (2) with a first sheet length (2 "), a second printed sheet (3) with a second sheet length (3") and a further first printed sheet (2) are provided with a first sheet length (2 "), and that for printed sheets (2, 3) of the same work order, the first sheet length (2") is essentially twice as long as the second sheet length (3 ").

Images