EP3533609B1 - Device and method for processing sequentially printed sheets - Google Patents

Description

The invention relates to a device and a method for the further processing of successive, sequentially printed printed sheets. The device has a conveyor for transporting the printed sheets in a conveying direction, a folding table arranged in a downstream area of the conveyor for receiving the printed sheets, a folding blade arranged vertically at a distance from the folding table, a pair of folding rollers arranged on a side of the folding blade opposite the folding blade with a pair of folding rollers formed in between Folding roller gap, at least one hold-down device arranged above the folding table and in its upstream area for pressing down a rear edge of a printing sheet to be positioned on the folding table in the direction of the folding table, with a leading edge of a subsequent printing sheet being fed in at a higher level than the rear edge of the printing sheet positioned on the folding table, and a machine control that is operatively connected to the folding blade and the at least one hold-down device.

During the process, the successive, sequentially printed printed sheets are transported from the conveyor in the conveying direction to the folding table arranged in the downstream area of the conveyor and picked up there by the latter, with the folding blade vertically spaced from the folding table and the folding blade arranged on a side of the folding table opposite the folding blade. Pair of rollers interact with the folding roller gap formed in between for folding the printed sheets and wherein the rear edge of a leading sheet to be positioned on the folding table is pressed in the direction of the folding table by means of the at least one hold-down device and the leading edge of the subsequent printing sheet is positioned opposite the rear edge of the leading sheet on the folding table Printing sheet is fed increased and the hold-down device and the folding blade are controlled by a machine control.

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

With digital printing, the print image is transferred directly from a computer to the printing machine without the use of static printing forms. The material web can be printed in the specified order of the finished printed product, i.e. sequentially, depending on the intended folding scheme. In this way, relatively small numbers 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 imprint itself, the number of printed pages per printed sheet and its respective format.

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

Downstream of the digital printing machine, the transport speed of the material web, which has meanwhile been separated from the material web, or that in the digital printing machine individually printed sheets can be reduced by folding one or more times with known longitudinal and / or transverse folding devices. On the one hand, the folding facilitates the careful further processing of the printed sheets, but each folding process potentially leads to an undesirable, larger number of blank pages. This can be avoided by using previously unfolded printed sheets. However, this increases the transport speed, which, depending on the further processing devices used, results in a high number of cycles and in turn makes gentle further processing more difficult and can lead to quality problems.

From the EP2818331 A2 a device and a method for inline further processing of a paper web sequentially printed by a digital printing machine are known. The printed paper web first passes through a perforating and cutting station. The printed sheets separated there are individually folded once or several times with cross and longitudinal folding devices. After folding, the printed sheets, which later form a common book block, are brought together like scales in a collating device before they are stacked and glued to form a book block in an adjoining stacking device. The book blocks are then transported for further processing.

With this solution, a certain reduction in the number of blank pages can be achieved due to an optimization of folding patterns that takes place automatically in the machine control in accordance with the respective production orders, depending on the number of uses. However, the costs, the space requirement and the control and regulation effort are relatively high due to the number of processing stations. Depending on the mode of operation of this device, the transport speed of the printed sheets to be transported through the device initially individually and at a very short distance one after the other after separation is also relatively high, so that quality problems can occur during their further processing.

The EP2502862 A1 discloses an apparatus and a method for processing printed sheets with different formats, which were also previously disclosed by have been severed from a web of material printed in a digital printing machine. The device has at least two collecting drums arranged one above the other for successive printed sheets with different formats. When operating the device, downstream of the collecting drums, for example by merging two printed sheets of different formats with a third printed sheet, a partial stack of three printed sheets is created, which can then be connected to another partial stack to form a printed product. For this purpose, the partial stacks can first be longitudinally and / or transversely folded downstream of their formation.

Due to the formation of partial stacks taking place by means of the two collecting drums, the transport speed of the partial stacks can advantageously be reduced in this solution in the downstream area of the print processing device. However, this requires a relatively complex drive of the two collecting cylinders, for example with a coupling gear or two separate drives that are to be coordinated with one another. A reduction in the number of blank pages is not disclosed.

From the EP2727868 A1 and the EP 2727869 A1 a device and a method for longitudinally or transversely folding by means of a digital printing machine sequentially printed printed sheets are known. The device has a compressed air device connected to a compressed air source and a control unit with a plurality of outlet openings for compressed air. With these solutions, relatively high transport speeds and thus high performance can be achieved. Due to the high transport speeds, however, under certain circumstances there may be quality problems when folding the printed sheets that follow one another at relatively short intervals. In order to avoid a collision between the trailing edge of a leading printed sheet and the leading edge of a trailing printed sheet during longitudinal folding, the leading printed sheet must always be conveyed out of the folding rollers or below the level of the folding table before the trailing printed sheet can be fed in. Even with these solutions, however, only successive individual printed sheets can be folded.

From the DE102016203043 A1 a folding machine with a knife folding station for folding successive, individual printed sheets with at least one lowerable and liftable folding blade and a pair of folding rollers arranged below the folding blade are known. The folding sword has a mechanical sword blade and a pneumatic sword blade arranged immediately upstream and in extension thereof, the latter having at least one nozzle for generating blown air. In addition, a downstream mechanical stop for braking the front edge of the printed sheet introduced into the knife folding station, an upstream pneumatic hold-down device for the rear edge of this printed sheet and a further upstream guide element for lifting a subsequent printed sheet when it enters the knife folding station are arranged in the folding machine. The printed sheets lie on rotating conveyor belts and are transported with them through the folding machine.

When the folding machine is in operation, the knife folding station is fed one after the other according to the pending production orders, and through the interaction of the folding blade with the folding rollers, they are each individually longitudinally folded. The printed sheets folded in this way are finally conveyed downwards for further processing. Due to the two-part folding blade with the pneumatic sword blade arranged in the upstream area, a subsequent printed sheet can be fed to the knife folding station without the risk of colliding with the folding blade when the previous printed sheet is being folded and is still partially on the conveyor belts. This means that either a higher folding performance can be achieved with the same transport speed or the transport speed can be reduced with the same folding performance. Shortly before the leading edge of the following sheet reaches the trailing edge of the preceding sheet, a hold-down force is applied to the trailing edge of the preceding printed sheet by means of the pneumatic hold-down device. Immediately thereafter, the leading edge of the following printed sheet is raised by means of the guide element. The combination of holding down and lifting can prevent these two printed sheets from colliding.

The air pulse of the pneumatic hold-down, in combination with conveyor belt air on both sides and above the folding table, with pneumatic hold-down elements or in combination with corresponding mechanical hold-down elements, ensures that the printed sheet is pressed against the conveyor belts by means of friction, recording their speed and thus being transported to the stop in a defined manner.

Despite the increased performance, this folding machine is only intended for relatively low transport speeds. Further increases in performance are therefore hardly possible. In addition, the stop is only suitable for low transport speeds because the printed sheet hitting it could be damaged and / or jump back from the stop at a high transport speed. Finally, this folding machine is only suitable for folding successive, individual printed sheets.

The EP3002240 A1 and the EP3002241 A1 each relate to a device for braking and positioning a printed sheet, for example, printed by means of a digital printing machine, in a processing machine and a method for operating such a device. In this way, individual printed sheets that have a high transport speed can be braked precisely, stably and completely in a very short time without the risk of injury. However, a mechanical folding knife is used here, to which each printed sheet is fed in the same plane in which it is positioned before the folding process. In order to be able to position a subsequent print sheet on the folding table, the previous print sheet must be withdrawn from the folding table so far that its trailing ends are below the feed level of the subsequent print sheet. This results in a relatively high withdrawal speed of the individual printed sheets from the folding table and into the pair of folding rollers. Under certain conditions, this can lead to quality problems during further processing, ie to turning over the trailing ends of a printed sheet and to folding so-called dog-ears. In addition, there is a risk of collision between a subsequent printed sheet and the mechanical folding blade. Finally, the fixed sequence of movements of the mechanical folding knife cannot be changed for consecutive, different printed sheets. Accordingly, this solution is also only suitable for folding successive, individual printed sheets.

The object of the invention was therefore to provide a simple and inexpensive device and a corresponding method for further processing of printed sheets sequentially printed by means of a digital printing machine, wherein the transport speed of the printed sheets can be reduced and yet improved performance can be achieved. In addition, careful further processing of the printed sheets should be made possible, thus avoiding quality problems and achieving a potential reduction in the number of blank pages in the finished printed product.

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 16. Advantageous embodiments are specified in the respective subclaims.

For this purpose, the at least one hold-down device of the device according to the invention has at least one mechanical braking element for this printed sheet which acts on the upper side of the rear edge of the printed sheet to be positioned on the folding table. In addition, the folding blade is designed to be stationary and has a compressed air device connected to a first compressed air source with at least one outlet opening directed towards the folding roller gap for initiating the folding of the printed sheets. Furthermore, the folding table forms a collecting device for at least two consecutive printed sheets. Finally, in the area of the conveyor, at least one sensor, which is operatively connected to the machine control, is arranged for detecting the printed sheets transported by the conveyor.

In the method according to the invention, at least two successive printed sheets are collected on the collecting device of the folding table to form a common stack and the stack is closed together folded a printed product. A leading printed sheet to be placed on the folding table is braked in the area of its rear edge on its upper side by contact with the mechanical braking element. The folding of the stack is triggered by the action of compressed air supplied from the first compressed air source from the at least one outlet opening of the fixed folding blade onto the stack. In addition, a printed sheet transported by the conveyor is detected with the at least one sensor that is operatively connected to the machine control and the machine control uses information received from the at least one sensor to calculate corresponding control signals for pressing down the trailing edge of the leading printed sheet, for braking it and for actuating the folding blade, and finally releases it pressing down, braking and folding.

In the case of the folding machine known from the prior art, only successive individual printed sheets can be folded. This is the case because a second printed sheet collected on the first printed sheet could not be pressed against the conveyor belts, but only against the first printed sheet already resting with its front edge against the stop. As a result, such a second printed sheet could no longer be transported cleanly to the stop. Such a folding machine is therefore not suitable for collecting printed sheets and for subsequent folding.

In contrast to this, with the device according to the invention and with the method according to the invention, not only can successive individual printed sheets be folded, but they can also be collected beforehand to form a stack. As a result, the transport speed of the printed sheets collected in a stack can be advantageously reduced compared to individually fed and individually folded printed sheets, both during the folding and after the folding. In addition to improved performance, this also results in a simple, inexpensive and compact device and a corresponding method. In addition, with lower procedural risks, a gentler further processing of the printed sheets and thus a better quality of the folded printed products can be realized. When feeding unfolded print sheets to the folding table, ie when stacking with the unfolded printed sheets included, a reduction in blank pages can ultimately also be achieved. In this context, further processing with the device according to the invention and the method according to the invention are mainly to be understood as feeding the individual printed sheets to the folding table, collecting these printed sheets on the folding table and then folding the stack consisting of the collected printed sheets.

In one embodiment of the device according to the invention, a stop for the front edges of the printed sheets to be collected on the folding table is arranged in the area of the folding table. Accordingly, in one embodiment of the method according to the invention, the front edges of the printed sheets to be collected on the folding table are conveyed against a stop arranged in the area of the folding table. In this way, an improved alignment of the printed sheets of the stack and thus an improved folding quality can be achieved.

According to a further embodiment of the device according to the invention, the stop is designed to be displaceable in and against the conveying direction of the printed sheets. According to a further embodiment of the method according to the invention, when the format of the printed sheets to be collected on the folding table is changed, the stop is shifted in or against the conveying direction of the printed sheets. The device can thus be adapted to printed sheets with different formats in a simple and inexpensive manner.

According to a next embodiment of the device according to the invention, the at least one hold-down device is connected to the first compressed air source or to a second compressed air source and has at least one outlet opening for compressed air directed towards the top of the printed sheet to be positioned on the folding table in the area of its rear edge. The at least one mechanical braking element is arranged between the at least one first outlet opening of the hold-down device and the folding table. According to a corresponding embodiment of the method according to the invention, the at least a hold-down device is supplied with compressed air from the first compressed air source or from a second compressed air source and the compressed air is directed through at least one outlet opening of the hold-down device onto the top of the printed sheet to be positioned on the folding table in the region of its rear edge. The compressed air emerging from the at least one first outlet opening of the hold-down device is directed to the at least one mechanical braking element, deflecting it in the direction of the folding table and bringing it into contact with the printed sheet to be positioned on the folding table or fed to the stack. This provides a simple, inexpensive and very quickly responding solution which also has hardly any moving parts, ie hardly any wear.

According to a further embodiment of the device according to the invention, it has at least two separate hold-down devices which are each arranged transversely to the conveying direction of the printed sheets at a lateral distance from an upstream end of the compressed air device of the folding blade. According to the corresponding method according to the invention, the compressed air is applied via the at least two separate hold-down devices. In this way, the printed sheets can advantageously be held down and braked evenly and without the risk of twisting.

According to a next embodiment of the device according to the invention, the lateral distance between the at least two separate hold-down devices is adjustable. According to the corresponding method according to the invention, the lateral distance between the at least two separate hold-down devices is correspondingly reduced or increased in a subsequent work order with a smaller or larger format of printed sheets to be processed. In this way, the hold-down devices can be adjusted according to the format of the printed sheets to be collected on the folding table. The entire rear edge of the respective printed sheet can thus be pressed down in the direction of the folding table, so that no areas of this printed sheet can collide with a trailing printed sheet.

In another embodiment of the device according to the invention, the Folding blade on a number of segments arranged one behind the other in the conveying direction. In the corresponding method according to the invention, the compressed air supplied by the first compressed air source is introduced into the segments of the folding blade, with compressed air only being applied to the segments arranged in the region of the stack by means of the machine control. Due to the formation of separate segments, these can be activated separately and pressurized with compressed air in a targeted manner in accordance with the format of the stack lying on the folding table. In addition, turbulence of compressed air in the free space between the folding blade and the stack to be folded can be prevented and thus impairment of the correct alignment of the uppermost printed sheet of the stack can be avoided.

According to a further embodiment of the device according to the invention, the conveyor has a lower belt and an upper belt cooperating with this for transporting the printed sheets. In the corresponding method according to the invention, the printed sheets are transported to the folding table in a conveyor gap formed between the lower belt and the upper belt of the conveyor. As a result, the printed sheets are clamped in the conveyor gap during their transport and can thus be accelerated or decelerated without slipping.

According to a next embodiment of the device according to the invention, both the lower belt and the upper belt extend into the area of the folding table. According to the corresponding method according to the invention, the printed sheets with the lower belt and the upper belt of the conveyor are transported into the area of the folding table. With this arrangement, the lower belt can transport the lowermost printed sheet of the stack to be formed against the stop and position it correctly there, while the upper belt can guide or guide the printed sheets on the folding table. In addition, only one drive is advantageously required for the upper belt and lower belt.

In another embodiment of the device according to the invention, the lower belt and / or the upper belt converge towards one another in the area of the folding table educated. In the corresponding method according to the invention, the guidance of the printed sheets in the area of the folding table is additionally supported by the converging formation of the lower belt and / or the upper belt.

According to a further embodiment of the device according to the invention, at least two sensors, which are operatively connected to the machine control system, are arranged in the area of the conveyor for detecting the printed sheets transported by the conveyor, spaced transversely to the conveying direction. In the corresponding method according to the invention, the printed sheets in the area of the conveyor are detected by means of the at least two sensors. In this way, any inclined position of a transported printed sheet can be identified and corrected, for example, by appropriately applying compressed air to the segments of the air sword or the hold-down device.

According to a next embodiment of the device according to the invention, the pair of folding rollers and the folding blade are arranged longitudinally or transversely to the conveying direction. With this solution, the stack can advantageously be folded both longitudinally and transversely to the conveying direction of the printed sheets transported by the conveyor. If the pair of folding rollers and the folding blade are arranged transversely to the conveying direction, the hold-down devices are arranged parallel thereto.

In another embodiment of the device according to the invention, the folding roller gap has a gap width which is designed to be adjustable. In the corresponding method according to the invention, the gap width is adjusted accordingly in a subsequent work order with a different thickness of the stack to be folded. In this way, the folding roller gap can advantageously be adapted to work orders with different stack thicknesses. This is done by a corresponding relative movement of the bearing points of the folding rollers. Alternatively, however, the folding rollers can also only be designed to be sprung and thereby compensate for different thicknesses of the stack to be folded within certain tolerance ranges.

Fig. 1

Eine schematische Seitenansicht einer erfindungsgemässen Vorrichtung zur Weiterverarbeitung von Druckbogen, gemäss eines ersten Ausführungsbeispiels,

Fig. 2

Eine vereinfachte, schematische Vorderansicht der erfindungsgemässen Vorrichtung gemäss des ersten Ausführungsbeispiels, dargestellt entgegen der Förderrichtung der Druckbogen,

Fig. 3

Eine schematische Seitenansicht einer erfindungsgemässen Vorrichtung zur Weiterverarbeitung von Druckbogen, gemäss eines zweiten Ausführungsbeispiels.

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 the further processing of printed sheets, according to a first exemplary embodiment,

Fig. 2

A simplified, schematic front view of the device according to the invention according to the first exemplary embodiment, shown against the conveying direction of the printed sheets,

Fig. 3

A schematic side view of a device according to the invention for the further processing of printed sheets, according to a second exemplary embodiment.

Fig. 1 _{shows a schematic side view of a device 1 according to the invention for further processing of printed sheets 2 1... n} sequentially printed by means of a digital printing machine (not shown) according to a first exemplary embodiment. As shown, the printed sheets 2 _{1... N} can not be folded, can be folded once or several times and can be fed to the device 1 in any order. The device 1 has a conveyor 3 for transporting the printed sheets 2 _{1 ... n} , here the printed sheets 2 ₄ , 2 ₅ , 2 ₆ and 2 _n , in a conveying direction 4, a folding table 6 arranged in a downstream area 5 of the conveyor 3 , a folding blade 7 arranged centrally above the folding table 6 and transversely to the conveying direction 4 and a pair of folding rollers 8 arranged below the folding table 6 with a first folding roller 9 and a second folding roller 10 arranged parallel thereto. The folding blade 7 has a holding element 7 'and is arranged on this adjustable in height ( Fig. 2 ). Of course, the folding blade 7 can also be arranged below and the pair of folding rollers 8 accordingly above the folding table 6 if required. In general, the result is an arrangement of the folding blade 7 vertically spaced from the folding table 6 and an arrangement of the pair of folding rollers 8 also vertically spaced from the folding table 6, but on its side opposite the folding blade 7.

The conveyor 3 has a lower belt 11, which is made up of several individual belts (not shown) that are arranged parallel to one another and are spaced transversely to the transport direction, and an upper belt 12 running parallel to this and interacting with the lower belt 11, between which a common conveyor gap 13 for the printed sheets 2 _{1. ..n is} trained. Both the lower belt 11 and the upper belt 12 extend into the area of the folding table 6. The lower belt 11 and the upper belt 12 can of course also be designed to converge there, so that a conveyor gap 13 'that is continuously narrowing in the area of the folding table 6 results ( Fig. 3 ).

The folding blade 7 is designed to be stationary and has a compressed air device 15 connected to a first compressed air source 14 with several segments 17 arranged one after the other in the conveying direction 4 and to be supplied separately with compressed air 16 ( Fig. 1 ). Each segment 17 has at least one outlet opening 18, which is aligned with the folding table 6, for the compressed air 16.

The folding table 6 forms a collecting device 6 'for successive printed sheets 2 _{1 ... n} . In the area of the folding table 6, a stop 19 for front edges 2 _{1 '... n' of the collected printed sheets 2 1 ... n} lying on the folding table 6, here the printed sheets 2 ₁ , 2 ₂ and 2 ₃ , is arranged and accordingly the format of this printed sheet 2 _{1 ... n designed to be} adjustable. For this purpose, the stop 19 is connected to a first setting device 20.

The two folding rollers 9, 10 each have an axis of rotation 9 ′, 10 ′, which are aligned parallel or almost parallel to one another and parallel to the folding table 6. The folding rollers 9, 10 are held at both ends 21, 22 in a bearing point 23, 24 ( Fig. 2 ). They are arranged at a distance from one another transversely to the conveying direction 4 and thus have a folding roller gap 25 formed between them for receiving and forwarding printed sheets 2 _{1... N} to be folded. The alignment of the axes of rotation 9 ', 10' of the folding rollers 9, 10 to one another and thus also the formation of the folding roller gap 25 can, depending on the thickness profile of the collected printed sheets 2 _{1 ... n} lying on the folding table 6, ie according to the folding scheme and / or the type of paper used, can be varied. The folding table 6 has a recess 6 ″ formed above the folding roller gap 25 for the passage of the printed sheets 2 _{1 ... n} to be folded. In addition, the folding rollers 9, 10 are driven in opposite directions and are connected to a drive motor 26 for this purpose ( Fig. 1 ). Finally, at the bearing points 23, 24 of the folding rollers 9, 10, a second adjusting device 27 is arranged on both sides for changing the mutual spacing of the folding rollers 9, 10, ie for adjusting the folding roller gap 25 or its gap width 25 '. Alternatively, the bearing points 23, 24 can also be mounted on springs.

To press down a rear edge 2 _{1 "... n" of a printed sheet 2 1 ... n} to be positioned on the folding table 6 in the direction of the folding table 6, a plurality of hold-down devices 29 are spaced transversely to the conveying direction 4 above the folding table 6 and in its upstream region 28 arranged from each other. In addition, the hold-down devices 29 are arranged transversely to the conveying direction 4 of the printed sheets 2 _{1... N} at a lateral distance 30 from an upstream end 15 ′ of the compressed air device 15 of the folding blade 7. This lateral distance 30 is designed to be adjustable by means of a third adjusting device 31, here only indicated by a double arrow. The hold-down devices 29 are connected to a second compressed air source 14 '. They each have at least one on the folding table 6 or on the top 2 _{1 '''...n''' of the printed sheet 2 1 ... n} to be positioned on the folding table 6 in the area of its rear edge 2 _{1 "... n "} directed outlet opening 32 for compressed air 33 to ( Fig. 1 , Fig. 2 , Fig. 3 ). For braking the printed sheet 2 _{1 ... n} approximately simultaneously with the pressing down of the rear edge 2 _{1 "... n"} , the hold-down devices 29 each have an area between their at least one outlet opening 32 for compressed air 33 and the folding table 6 and in the area the rear edge 2 _{1 "... n"} on the upper side 2 _{1 '''...n''' of the printing sheet 2 1 ... n} to be positioned on the folding table 6, mechanical braking element 34 for this printing sheet 2 _{1. ..n} . Depending on requirements, only a single hold-down device 29 can of course be used, which is then arranged centrally, viewed transversely to the conveying direction 4, ie essentially in the vertical plane through the folding blade 7.

The device 1 has a machine control 35 that is operatively connected to the folding blade 7 and the hold-downs 29. To control the folding blade 7 and the hold-down device 29, corresponding control lines 36 with solenoid valves 37 are provided. In the area of the conveyor 3, at least one sensor 38, which is operatively connected to the machine control 35, for detecting the printed sheets 2 _{1... N} transported by the conveyor 3 is arranged. For this purpose, the sensor 38 is connected to the machine control 35 via a data line 39.

Figure 2 shows a simplified, schematic front view of the device 1 according to FIG Fig. 1 , shown against the conveying direction 4 of the printed sheets 2 _{1 ... n} . In particular, the holding element 7 'of the folding blade 7, the individual belts of the lower belt 11 of the conveyor 3 embedded in the folding table 6, the gap width 25' of the folding roller gap 25 and the lateral distance 30 of the respective hold-down device 29 from the compressed air device 15 of the Folding sword 7 to be seen.

When operating the device 1, the leading edge 2 _{1 '... n' of} a subsequent printed sheet 2 _{1 ... n} , ie in Fig. 1 of the printed sheet 2 ₄ , opposite the rear edge 2 _{1 "... n" of the printed sheet 2 1 ... n} positioned on the folding table 6, ie in Fig. 1 of the printing sheet 2 ₃ , fed increased. This can be done by means of a fixed or adjustable step 40 shown here in the lower belt 11 ( Fig. 1 , Fig. 2 ), by an active element (not shown) or a ramp (also not shown), which in each case the front edge 2 _{1 '... n' of} the subsequent printed sheet 2 _{1 ... n} compared to the rear edge 2 _{1 "... n" of} the on the Folding table 6 positioned print sheet 2 _{1 ... n} lifts can be reached.

After a number of printed sheets 2 _{1 ... n} corresponding to the current work order have been collected on the folding table 6 forming the collecting device 6 ', that is to say placed on top of one another to form a stack 41, this stack 41 is then folded by means of the folding blade 7 and the pair of folding rollers 8 and in this way a folded printed product 41 'is produced.

For this purpose, the corresponding solenoid valves 37 of the folding blade 7 are first opened by means of the machine control 35. Compressed air 16 therefore flows from the first compressed air source 14 into the segments 17 of the compressed air device 15. These _{Compressed air 16 hits the stack 41 or the top side 2 1 '''...n''' of} the uppermost printed sheet 2 _{1 ... n} via the outlet openings 18 of the segments 17 in such a manner that the stack 41 passes through the Recess 6 ″ of the folding table 6 and between the individual bands of the lower band 11 is pressed into the folding roller gap 25 of the folding roller pair 8 and is finally folded by means of the folding rollers 9, 10. The impulse for opening the solenoid valves 37 and thus for folding the stack 41 is first triggered when a subsequent print sheet 2 _{1 ... n has} an overlap 42 with respect to the stack 41 resting on the folding table 6 ( Fig. 1 ). When the stack 41 enters between the folding rollers 9, 10, this on the one hand prevents the supply of the subsequent printed sheet 2 _{1... N from being} blocked in the free space located between the stack 41 and the upper belt 12. On the other hand, the trailing printed sheet 2 _{1 ... n forms} a guide for the ends of the printed sheet 2 _{1 ... n of} the stack 41 to be folded that last through the folding rollers 9, 10 Due to their relatively high acceleration during transport, ends are turned over in the vertical direction and bent over by the folding rollers 9, 10. The length of the overlap 42 is approximately 1 to 20% of the length of a printed sheet 2 _{1... N of} the stack 41.

Due to the subdivision of the compressed air device 15 of the folding blade 7 into several segments 17, advantageously only those required according to the format of the printed sheets 2 _{1 ... n} to be folded or the stack 41 formed therefrom, ie the segments 17 arranged in the area of the stack 41 are acted upon by compressed air 16, while the segments 17 which are not required, ie which are arranged outside this area, remain closed by not actuating their solenoid valves 37. In this way, on the one hand, compressed air 16 can be saved and, on the other hand, it is prevented that unneeded compressed air penetrates into the free space between the folding blade 7 and the stack 41 to be folded and there possibly causing turbulence and impairment of the correct alignment of the uppermost printed sheet 2 _{1. n of} the stack 41 leads.

The printed product 41 ′ formed by folding the stack 41 is formed from individual strips 43, for example, which adjoin the pair of folding rollers 8 Transport device 44 conveyed away for intermediate storage or further processing. If only the stop 19 is adapted to the format of the printed sheets 2 _{1... N} forming a common stack 41, the printed product 41 ′ is conveyed away eccentrically from the transport device 43, as shown in FIG Fig. 3 is shown. On the other hand, if, in addition to the stop 19, the step 40 and the hold-down device 29 are also adjusted accordingly in or against the conveying direction 4, the printed product 41 ′ can be conveyed away centrally on the conveying device 43.

If printed sheets 2 _{1 ... n of} a larger or smaller format compared to the current work order are to be processed with the device 1, the stop 19 can be adjusted by means of the first adjusting device 20 in or against the conveying direction 4 in such a way that these printed sheets 2 _{1. ..n are also placed one on top of the} other on the folding table 6 forming the collecting device 6 'in such a way that a stack 41 of these printed sheets 2 _{1 ... n is} formed. In addition, a corresponding adjustment of the step 40 and the hold-down device 29 can also take place in or against the conveying direction 4.

Due to the height-adjustable arrangement of the folding blade 7 on the holding element 7 ', the vertical distance of the folding blade 7 to the folding table 6 can be adjusted accordingly in a subsequent work order with a different thickness of the stack 41 to be folded of printed sheets 2 _{1 ... n.} In this way, this vertical distance can advantageously be adapted to the number of printed sheets to be folded and also to the type of paper.

Due to the stack formation that takes place with this device 1 before folding, the transport speed of the printed sheets 2 _{1... N} located in the stack 41 can be reduced in a simple and inexpensive manner compared to the individually folded printed sheets of the prior art. Depending on the further processing devices used downstream of the device 1, a lower number of cycles can thus be implemented, which enables gentle further processing while avoiding quality problems. Due to the feeding of previously unfolded printed sheets 2 _{1 ... n} to the folding table 6, which is possible in a simple manner compared to the known prior art, the number of blank pages in the stack 41 and thus in the printed product 41 'can be reduced in a simple manner without increasing the transport speed. As a result, quality problems in the devices used for further processing can be avoided.

Figure 3 shows a second embodiment with a device 1 'according to the invention in which both the lower belt 11 and the upper belt 12 of the conveyor 3 each have two conveyor belts 11', 11 ", 12 ', 12" arranged one after the other in the conveying direction 4. Of course, more than two conveyor belts 11 ', 11 ", 12', 12" can also be arranged in each case. As a result, the folding table 6, the folding blade 7 and the pair of folding rollers 8 of the device 1 'can advantageously be separated from the conveyor 3, ie from the feed of the printed sheets 2 _{1... N.}

In contrast to the first exemplary embodiment, the compressed air device 15 is not configured in a segmented manner here, as a result of which the device 1 'can be manufactured even more simply and cost-effectively. Like the compressed air device 15, the hold-down devices 29 are also connected to the first compressed air source 14, so that advantageously no second compressed air source is required. In addition, the upper belt 12 tapers towards the lower belt 11 in the area of the folding table 6, i.e. is designed with a conveyor gap 13 'converging in the conveying direction 4, which _{results in additional support for guiding the printed sheets 2 1 ... n} in the area of the folding table. Of course, the lower belt 11 can also run towards the upper belt 12, or both belts 11, 12 can run towards one another.

Devices according to the invention and corresponding methods according to the invention are also conceivable in which the different features of the first and second exemplary embodiments are combined with one another in different ways.

Claims (28)

1. Device for processing sequentially printed sheets (2_1...n) following one another, comprising

   • a conveyor (3) for transporting the printed sheets (2_1...n) in a conveying direction (4),

   • a folding table (6) for receiving the printed sheets (2_1...n), arranged in a downstream region (5) of the conveyor (3),

   • a folding blade (7) arranged at a vertical distance from the folding table (6),

   • a pair of folding rollers (8) arranged on a side of the folding table (6) that is opposite the folding blade (7) and having a folding roller gap (25) formed between them,

   • at least one hold-down (29) arranged above the folding table (6) and in the upstream region (28) of the latter for pressing down a trailing edge (2_1"...n") of a printed sheet (2_1...n) to be positioned on the folding table (6) in the direction of the folding table (6), wherein a leading edge (2_1'...n') of a following printed sheet (2_1...n) is supplied elevated relative to the trailing edge (2_1"...n") of the printed sheet (2_1...n) positioned on the folding table (6),

   • a machine control system (35) operatively connected to the folding blade (7) and the at least one hold-down (29),

   characterized in that

   • the at least one hold-down (29) has at least one mechanical braking element (34), which acts, in the region of the trailing edge (2_1"...n") of the printed sheet (2_1...n) to be positioned on the folding table (6) and on the upper side (2_1'''...n''') thereof, for this printed sheet (2_1...n) ,

   • the folding blade (7) is designed to be stationary and has a compressed air device (15) connected to a first compressed air source (14) and having at least one outlet opening (18) aimed at the folding roller gap (25) for introducing compressed air (16) used to fold printed sheets (2_1...n),

   • the folding table (6) forms a collecting device (6') for at least two printed sheets (2_1...n) following one another,

   • at least one sensor (38) operatively connected to the machine control system (35) is arranged in the region of the conveyor (3) to detect the printed sheets (2_1...n) transported by the conveyor (3) .
2. Device according to Claim 1, characterized in that a stop (19) for leading edges (2_1'...n') of the printed sheets (2_1...n) that are to be collected on the folding table (6) is arranged in the region of the folding table (6) .
3. Device according to Claim 2, characterized in that the stop (9) is designed to be displaceable in and counter to the conveying direction (4) of the printed sheets (2_1...n).
4. Device according to one of Claims 1 to 3, characterized in that the at least one hold-down (29) is connected to the first compressed air source (14) or to a second compressed air source (14'), and has at least one outlet opening (32) for compressed air (33) that is aimed at the upper side (2_1'''...n''') of the printed sheet (2_1...n) to be positioned on the folding table (6), in the region of its trailing edge (2_1"...n") .
5. Device according to Claim 4, characterized in that the at least one mechanical braking element (34) is arranged between the at least one first outlet opening (32) of the hold-down (29) and the folding table (6).
6. Device according to one of Claims 1 to 5, characterized in that it has at least two separate hold-downs (29), which are each arranged transversely relative to the conveying direction (4) of the printed sheets (2_1...n) at a lateral distance (30') from an upstream end (15') of the compressed air device (15) of the folding blade (7) .
7. Device according to Claim 6, characterized in that the lateral distance (30) between the at least two separate hold-downs (29) is adjustable.
8. Device according to one of Claims 1 to 7, characterized in that the folding blade (7) has a number of segments (17) arranged one after another in the conveying direction (4).
9. Device according to one of Claims 1 to 8, characterized in that the conveyor (3) has a lower belt (11, 11', 11") and an upper belt (12, 12', 12") interacting therewith to transport the printed sheets (2_1...n).
10. Device according to Claim 9, characterized in that both the lower belt (11, 11') and the upper belt (12, 12") reach into the region of the folding table (6).
11. Device according to Claim 10, characterized in that the lower belt (11, 11") and/or the upper belt (12, 12") are designed to converge in the region of the folding table (6).
12. Device according to one of Claims 1 to 11, characterized in that at least two sensors (38) operatively connected to the machine control system (35) to detect the printed sheets (2_1...n) transported by the conveyor (3) are arranged in the region of the conveyor (3) at a distance from each other transversely relative to the conveying direction (4).
13. Device according to one of Claims 1 to 12, characterized in that the pair of folding rollers (8) and the folding blade (7) are arranged longitudinally or transversely relative to the conveying direction (4).
14. Device according to one of Claims 1 to 13, characterized in that the folding roller gap (25) has a gap width (25') which is adjustable.
15. Method of processing sequentially printed sheets (2_1...n) following one another, which are transported by a conveyor (3) in a conveying direction (4) to a folding table (6) arranged in a downstream region (5) of the conveyor (3) and are received by the folding table (6) there, wherein a folding blade (7) arranged at a vertical distance from the folding table (6), and a pair of folding rollers (8) which are arranged on a side of the folding table (6) that is opposite the folding blade (7) and which have a folding roller gap (25) formed between them, interact to fold the printed sheets (2_1...n), and wherein a trailing edge (2_1"...n") of a preceding printed sheet (2_1...n) to be positioned on the folding table (6) is pressed by means of at least one hold-down (29) in the direction of the folding table (6), and a leading edge (2_1'...n') of a following printed sheet (2_1...n) is supplied elevated relative to the trailing edge (2_1"...n") of the preceding printed sheet (2_1...n) positioned on the folding table (6), and wherein the hold-down (29) and the folding blade (7) are controlled via a machine control system (35), characterized in that at least two printed sheets (2_1...n) following one another, forming a common stack (41), are collected on one another on a collecting device (6') of the folding table (6) and the stack (41) is folded jointly to form a printed product (41'), wherein a preceding printed sheet (2_1...n) to be laid on the folding table (6) is braked by contact with a mechanical braking element (34) on its upper side (2_1'''...n''') in the region of its trailing edge (2_1"...n"), wherein the folding of the stack (41) is triggered by the action of compressed air (16) supplied from a first compressed air source (14) from at least one outlet opening (18) of the stationary folding blade (7) onto the stack (41), and wherein a printed sheet (2_1...n) transported by the conveyor (3) is detected by a sensor (38) operatively connected to the machine control system (35), and, from information obtained from at least one sensor (38), the machine control system (35) calculates appropriate control signals for pressing down the trailing edge (2_1"...n") of the preceding printed sheet (2_1...n) , to brake the same and to actuate the folding blade (7), and triggers the pressing down, the braking operation and the folding operation.
16. Method according to Claim 15, characterized in that the leading edges (2_1'...n') of the printed sheets (2_1...n) to be collected on the folding table (6) are conveyed against a stop (19) arranged in the region of the folding table (6).
17. Method according to Claim 16, characterized in that in the event of a change in format of printed sheets (2_1...n) to be collected on the folding table (6), the stop (19) is displaced in or counter to the conveying direction (4) of the printed sheets (2_1...n).
18. Method according to one of Claims 15 to 17, characterized in that the at least one hold-down (29) is supplied with compressed air (16, 33) from the first compressed air source (14) or from a second compressed air source (14'), and the compressed air (16, 33) is supplied by at least one outlet opening (32) of the hold-down (29), aimed at the upper side (2_1'''...n''') of the printed sheet (2_1...n) to be positioned on the folding table (6), in the region of its trailing edge (2_1"...n").
19. Method according to one of Claims 15 to 18, characterized in that the compressed air (16, 33) emerging from the at least one first outlet opening (32) of the hold-down (29) is conducted to the at least one mechanical braking element (34), the latter is deflected in the direction of the folding table (6) as a result and is brought into contact with the printed sheet (2_1...n) to be positioned on the folding table (6) or to be supplied to the stack (41).
20. Method according to one of Claims 15 to 19, characterized in that the compressed air (16, 33) is applied via at least two separate hold-downs (29), which are each arranged transversely relative to the conveying direction (4) of the printed sheets (2_1...n) at a lateral distance (30') from an upstream end (15') of the compressed air device (15) of the folding blade (7).
21. Method according to Claim 20, characterized in that the lateral distance (30) between the at least two separate hold-downs (29) is reduced or enlarged appropriately in the event of a following job having a smaller or larger format of printed sheets (2_1...n) to be processed.
22. Method according to one of Claims 15 to 21, characterized in that the compressed air (16) supplied from the first compressed air source (13) is introduced into a number of segments (17) of the folding blade (7) that are arranged one after another in the conveying direction (4), wherein compressed air (16) is applied by means of the machine control system (35) only to the segments (17) arranged in the region of the stack (41).
23. Method according to one of Claims 15 to 22, characterized in that the printed sheets (2_1...n) are transported to the folding table (6) in a conveying gap (13) formed between a lower belt (11, 11', 11") and an upper belt (12, 12', 12") of the conveyor (3).
24. Method according to Claim 23, characterized in that the printed sheets (2_1...n) are transported into the region of the folding table (6) by the lower belt (11, 11') and the upper belt (12, 12") of the conveyor (3).
25. Method according to Claim 24, characterized in that the guidance of the printed sheets (2_1...n) in the region of the folding table (6) is additionally supported by a converging design of the lower belt (11, 11') and/or the upper belt (12, 12").
26. Method according to one of Claims 15 to 25, characterized in that in the region of the conveyor (3) the printed sheets (2_1...n) are detected by means of at least two sensors (38) that are operatively connected to the machine control system (35) and are arranged at a distance transversely relative to the conveying direction (4) .
27. Method according to one of Claims 15 to 26, characterized in that the stack (41) is folded longitudinally or transversely relative to the conveying direction (4) of the printed sheets (2_1...n) transported by the conveyor (3).
28. Method according to one of Claims 15 to 27, characterized in that in the event of a following job having a different thickness of the stack (41) to be folded, a gap width (25') of the folding roller gap (25) is adjusted appropriately.

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