Apparatus and method for variable-format cutting of a ribbon

Abstract

The invention relates to a cross-cutting unit (1) for a folding unit for format-variable cutting of a folded or unfolded strand (2) entering with a direction LR into a plurality of signatures (3), comprising a first cross-cutting device (4) for separating signatures (3) from the strand (2) with a first section length L1, a second cross-cutting device (5) for separating signatures (3) from the strand (2) with a second section length L2, as well as a method and a corresponding folding unit for this purpose. The invention is based on the objective of providing a solution that ensures format-variable cross-cutting of an incoming strand (2) with a small footprint and short changeover times.The problem is solved according to the invention by arranging the first cross-cutting device (4) upstream of the second cross-cutting device (5) in the direction of travel LR and wherein the first cross-cutting device (4) and the second cross-cutting device (5) can be activated alternately, as well as a corresponding method and folding unit for this purpose.

Description

[0001] The invention relates to a cross-cutting unit for a folding machine for format-variable cutting of a folded or unfolded strand running with a direction LR into a plurality of signatures, comprising a first cross-cutting device for separating signatures from the strand with a first section length L1, a second cross-cutting device for separating signatures from the strand with a second section length L2.

[0002] The invention further relates to a folding device for separating a folded or unfolded strand running in a direction LR into a plurality of signatures with a first section length L1 or a second section length L2.

[0003] The invention further relates to a method for format-variable cutting of a folded or unfolded strand running with a direction LR into a plurality of signatures by means of a cross-cutting unit, wherein the strand is cut either with a first cross-cutting device for separating signatures from the strand with a first section length L1 or with a second cross-cutting device for separating signatures from the strand with a second section length L2.

[0004] For rotary printing presses, various folding unit concepts and technical solutions are known from the state of the art to separate an incoming strand into signatures with different section lengths using only one folding unit and / or a cross-cutting unit.

[0005] On the one hand, so-called format-variable cutting devices are known, in which different section lengths are produced with a fixed-format cutting cylinder by means of different peripheral speeds and / or variable peripheral speeds. However, such cross-cutting devices have the disadvantage that, due to the relative speeds occurring in most section lengths between the outer surface of the cutting blade cylinder and thus the cutting blade and the strand to be cut, considerable fluctuations in strand tension occur, resulting in large deviations in the cutting register and a high amount of dust and chip formation.

[0006] DE 102 13 978 A1 teaches a transverse cutting device in which the cutting cylinder has a variable peripheral speed during one revolution in order to avoid relative speed at least at the moment of cutting the strand. However, the possible range of format variability is limited with this method.

[0007] Solutions are also known from the prior art for designing the cutting knife cylinder with a plurality of grooves into which cutting knives can be inserted as needed. However, with this method, the change in section length is only possible in relatively large increments and requires a long changeover time due to the manual retooling of the knife cylinder and the groove cylinder, which is detrimental to the availability of the system.

[0008] DE 10 2012 103 711 A1 discloses a folding unit with a cassette that is movable perpendicular to the strand direction and contains a plurality of adjacent pairs of cutting cylinders with different section lengths. However, such a design with a translationally movable cassette containing a plurality of cutting cylinders of different section lengths is technically complex and also requires a very large amount of space.

[0009] The invention is therefore based on the objective of creating a solution that ensures format-variable cross-cutting of an incoming strand with minimal space requirements and short changeover times.

[0010] The problem is solved according to the invention by arranging the first cross-cutting device upstream of the second cross-cutting device in the direction of travel LR and by making the first cross-cutting device and the second cross-cutting device alternately activatable.

[0011] The problem is further solved according to the invention by a folding unit which includes such a transverse cutting unit.

[0012] Furthermore, the object of the invention is solved by a method in which the strand is either cut by the first transverse cutting device in signatures of the first section length L1 and the second transverse cutting device is passed through without cutting by the signatures with the first section length L1, or the first transverse cutting device is passed through without cutting by the strand and the strand is cut by the second transverse cutting device in signatures with the second section length L2.

[0013] Such a device or method offers the advantage that the infeed section of a folding unit can be implemented in the proven manner, that technically complex and space-consuming cassettes are avoided, and that, in particular, only a very small amount of time is required to change the section length, since this is possible by switching on or off the first or second cross-cutting device, similar to the pressure setting in printing units.

[0014] According to one embodiment of the invention, the first transverse cutting device comprises a first pair of cutting cylinders comprising a first knife cylinder and a first groove cylinder for single-cutting of the strand and / or the second transverse cutting device comprises a second pair of cutting cylinders comprising a second knife cylinder and a second groove cylinder for single-cutting of the strand.

[0015] This design has the advantage that the cross-cutting unit comprises only at least two pairs of cutting cylinders, thus enabling a very space-saving design.

[0016] According to a further embodiment of the invention, a first infeed conveyor is arranged upstream of the first cross-cutting device and a first outfeed conveyor is arranged downstream of the first cross-cutting device in the direction of travel LR of the strand, and / or a second infeed conveyor is arranged upstream of the second cross-cutting device and a second outfeed conveyor is arranged downstream of the second cross-cutting device in the direction of travel LR of the strand.

[0017] Such a design has the advantage that both the incoming strand and the separated signatures are guided well immediately after separation, and that the strand or the separated signatures can be conveyed through the inactive cross-cutting device without contact, thus avoiding product damage such as markings.

[0018] According to a further embodiment of the invention, the first transverse cutting device comprises a first pre-perforating cylinder pair and a first through-perforating cylinder pair arranged downstream of it in the direction of travel LR and / or the second transverse cutting device comprises a second pre-perforating cylinder pair and a second through-perforating cylinder pair arranged downstream of it in the direction of travel LR.

[0019] Such a design has the advantage that the strand is not only cut across by one cut, but that the strand is cut by two cuts that are spatially and therefore also temporally offset from each other.

[0020] By this multiple cutting, as is also described, for example, in DE 10 2022 111 571 A1, it is possible to guide the strand and / or the signatures in a transport system before, during and also immediately after the respective cut, so that neither the strand nor each signature is subject to any offset in the transport direction as well as perpendicular or oblique to it, which has a very advantageous effect on the accuracy of possibly subsequent collecting or folding processes.

[0021] According to a further embodiment of the invention, viewed in the direction of travel LR, the first pre-perforating cylinder pair is arranged upstream of the second pre-perforating cylinder pair, and the first through-perforating cylinder pair and the second through-perforating cylinder pair are arranged downstream of the second pre-perforating cylinder pair.

[0022] This design offers the advantage that the two pairs of pre-perforating cylinders are arranged directly next to each other downstream, despite their different section lengths, and that the two pairs of through-perforating cylinders are also arranged directly next to each other downstream, despite their different section lengths. Thus, a single conveyor system designed as a belt conveyor can be used for both pairs of pre-perforating cylinders, provided the lateral positioning of the areas to be perforated is identical. Furthermore, a single conveyor system designed as a belt conveyor can also be used for both pairs of through-perforating cylinders, provided the lateral positioning of the areas to be perforated is identical. This reduces the number of belt conveyor systems and also decreases the required installation space.

[0023] According to a further embodiment of the invention, the first pair of perforating cylinders is arranged upstream of the second pair of perforating cylinders when viewed in the direction of travel LR.

[0024] Such a design offers the advantage that, for both section lengths, the strand is separated at the same spatial and temporal intervals from the pre-perforation to the through-perforation, which consequently results in the same cutting behavior for both the first and second section lengths.

[0025] According to a further embodiment of the invention, the first transverse cutting device has a first circumference U1 which corresponds to the first section length L1 or an even multiple of the first section length L1 and / or the second transverse cutting device has a second circumference U2 which corresponds to the second section length L2 or an even multiple of the second section length L2.

[0026] This design has the advantage that there is no relative velocity between the first and / or second transverse cutting device and the strand to be cut, thus preventing strand flutter and voltage surges. This design is advantageous both for single-cutting and multi-cutting using pre-perforation and through-perforation.

[0027] Preferred embodiments of the invention are described in the dependent claims and the following description. Various exemplary embodiments of the invention are explained in more detail with reference to the drawings, without being limited thereto. These show: Fig. 1 The fundamental importance of variable-format cutting of strands. Fig. 2 An exemplary cross-cutting unit with a first and second cross-cutting device designed as a pair of cutting cylinders. Fig. 3 An exemplary cross-cutting unit with a first and second cross-cutting device designed as a pre-perforating cylinder pair and a through-perforating cylinder pair, respectively. Fig. 4 An exemplary cross-cutting unit with a first and second cross-cutting device designed as a pre-perforating cylinder pair and a through-perforating cylinder pair, respectively. Fig. 5 A side view of the in Fig. 4 The illustrated design serves to clarify the simplified transport system.

[0028] Fig. 1 shows a symbolic representation of the format-variable cutting of a file with an infeed direction LR, for example, into a file in Fig. 1 Folding unit not shown, incoming strand 2. Strand 2 can either be unfolded or folded before entering by means of a Fig. 1 The not-shown folding funnel may have been folded. Strand 2 can comprise only one layer of a substrate; however, it is also possible that strand 2 comprises several superimposed layers, for example, by dividing a Fig. 1 The track not shown has been divided into a number of sub-tracks.

[0029] Strand 2 passes through a Fig. 1symbolically represented cross-cutting unit 1, wherein in the cross-cutting unit 1 the strand 2 is either separated into a plurality of signatures 3 of a first section length L1 or into a plurality of signatures 3 of a second section length L2, wherein the first section length L1 is different from the second section length L2.

[0030] Fig. 2 Figure 1 shows an exemplary design of such a cross-cutting unit 1 for format-variable singulation of a strand 2 entering with a running direction LR into a plurality of signatures 3. Although in the Figures 2 to 4 As shown by way of example, strand 2 enters the cross-cutting unit 1 in a vertical direction; however, it is also possible for strand 2 to enter the cross-cutting unit 1 in any direction, and the orientation of the running direction LR can also be, for example, in the horizontal direction.

[0031] The in Fig. 2The illustrated embodiment of a format-variable cross-cutting unit 1 comprises a first cross-cutting device 4 and a second cross-cutting device 5. The first cross-cutting device 4 comprises a first cutting cylinder pair 6, wherein the first cutting cylinder pair 6 comprises a first knife cylinder 12-1 and a first groove cylinder 13-1.

[0032] The first knife cylinder 12-1 comprises a cutting knife 17, wherein - although in Fig. 2 Not shown, it is also possible that the first knife cylinder 12-1 has a plurality of cutting blades 17 around its circumference. The cutting blade 17 is designed such that it cuts through the strand 2 with only one cut, thus with a single cut across its entire width.

[0033] The first groove cylinder 13-1 includes a cutting edge 18, which serves as a support for the cutting blade 17 to cut through the strand 2. Although in Fig. 2Not shown, it is also possible that the first groove cylinder 13-1 has a plurality of cutting strips 18 on its circumference.

[0034] Due to the exemplary one-piece design of the first cutting cylinder 12-1 and the first groove cylinder 13-1, the diameter of the first cutting cylinder 12-1 and the first groove cylinder 13-1 is dimensioned such that the circumference of the first cutting cylinder 12-1 and the first groove cylinder 13-1 corresponds to the first section length L1. This avoids a relative velocity between the first transverse cutting device 4 and the strand 2.

[0035] At the in Fig. 2 In the example shown, the first cross-cutting device 4 is deactivated, meaning that the first knife cylinder 12-1 is disconnected from the first groove cylinder 13-1, so that the strand 2 is not cut by the first cross-cutting device 4.

[0036] The second knife cylinder 12-2 comprises a cutting knife 17, wherein - although in Fig. 2 Not shown – it is also possible that the second knife cylinder 12-2 has a plurality of cutting blades 17 around its circumference. The cutting blade 17 is designed such that it cuts through the strand 2 with only one cut, thus with a single cut across its entire width.

[0037] The second groove cylinder 13-2 includes a cutting edge 18, which serves as a support for the cutting blade 17 to cut through the strand 2. Although in Fig. 2 Not shown, it is also possible that the second groove cylinder 13-2 has a plurality of cutting edges 18 on its circumference.

[0038] Due to the exemplary one-piece design of the second cutting cylinder 12-2 and the second groove cylinder 13-2, the diameter of the second cutting cylinder 12-2 and the second groove cylinder 13-2 is dimensioned such that the circumference of the second cutting cylinder 12-2 and the second groove cylinder 13-2 corresponds to the second section length L2. This avoids a relative velocity between the second transverse cutting device 5 and the strand 2. Although the Figures 2 to 4 Although not shown to scale, it is still evident that the first section length L1 differs from the second section length L2.

[0039] At the in Fig. 2 In the example shown, the second cross-cutting device 5 is activated, meaning that the second knife cylinder 12-2 is engaged with the second groove cylinder 13-2, so that the strand 2 is cut by the second cross-cutting device 5.

[0040] To change the signatures from the second section length L2 to the first section length L1, only the second cross-cutting device 5 needs to be deactivated and the first cross-cutting device 4 activated. Deactivation can be achieved, for example, by pivoting the second knife cylinder 12-2 and / or the second groove cylinder 13-2, whereby the corresponding cylinders are pivoted or retracted, for example, by means of a lever or an eccentric bushing. The deactivated cross-cutting device 4, 5 can also be stopped with respect to its rotation. However, depending on the drive concept, it is also possible that the corresponding knife cylinders 12 or groove cylinders 13 may continue to rotate about their longitudinal axis even when stopped.Depending on the contour of the knife cylinders 12 and the groove cylinders 13, it is also possible to deactivate by simply bringing the corresponding cylinders into a defined position, so that the strand 2 and / or a signature 3 can pass between the cylinders without contact.

[0041] Fig. 2 The diagram also shows, very schematically represented as triangles, the belt lines for transporting strand 2 and / or the signatures 3 in the direction of travel LR of strand 2, seen before and after the first cross-cutting device 4 and before and after the second cross-cutting device 5.

[0042] Viewed in the direction of travel LR of strand 2, a first infeed conveyor 14-1 is located upstream of the first pair of cutting cylinders 6, and a first outfeed conveyor 15-1 is located downstream of the first pair of cutting cylinders 6. Furthermore, viewed in the direction of travel LR of strand 2, a second infeed conveyor 14-2 is located upstream of the second pair of cutting cylinders 7, and a second outfeed conveyor 15-2 is located downstream of the second pair of cutting cylinders 7. Both the infeed conveyors 14 and the outfeed conveyors 15 are designed as a single conveyor with several driven conveyor belts arranged across the width of strand 2, which guide strand 2 on both sides of strand 2 and on both sides of signature 3, respectively.Since both the first cross-cutting device 4 and the second cross-cutting device 5 completely cut through the strand 2 with a single cut, both the infeed conveyor lines 14 and the outfeed conveyor lines 15 must end before and after the respective cutting cylinder pair 6, 7, respectively.

[0043] Fig. 3 Figure 1 shows a further embodiment of a transverse cutting unit 1, wherein the first transverse cutting device 4 comprises a first pre-perforating cylinder pair 8 and a first through-perforating cylinder pair 10 arranged downstream of it in the direction of travel LR, and wherein the second transverse cutting device 5 comprises a second pre-perforating cylinder pair 9 and a second through-perforating cylinder pair 11 arranged downstream of it in the direction of travel LR.

[0044] The first pre-perforating cylinder pair 8 comprises a first pre-perforating knife cylinder 19-1 and a blanking cylinder 13, each with a first section length L1. The first through-perforating cylinder pair 10 comprises a first through-perforating knife cylinder 20-1 and a groove cylinder 13, each with a first section length L1.

[0045] The second pre-perforating cylinder pair 9 comprises a second pre-perforating knife cylinder 19-2 and a blanking cylinder 13, each with a second section length L2. The second through-perforating cylinder pair 11 comprises a second through-perforating knife cylinder 20-2 and a groove cylinder 13, each with a second section length L2.

[0046] Although in Fig. 3If not shown, it is also possible that the pre-perforating knife cylinders 19 and / or the through-perforating knife cylinders 20 and / or the groove cylinders 13 have a plurality of perforating knife strips or groove beams on their circumferences.

[0047] Each pre-perforating cylinder 19 comprises at least one pre-perforating blade strip which, viewed from the first position, cuts through the strand 2 across its width. The width of these pre-perforated sections can be, for example, 10 to 50 mm. Each through-perforating cylinder 20 comprises at least one through-perforating blade strip which, viewed from the second position, cuts through the strand 2 across its width. These second positions are offset from the first positions. The width of these perforated sections can be, for example, 10 to 50 mm. Due to the lateral offset of the first and second positions, the strand 2 is thus completely cut through across its width with two perforation cuts.

[0048] At the in Fig. 3In the example shown, the second cross-cutting device 5 is activated, meaning that the second pre-perforating knife cylinder 19-2 is attached to the groove cylinder 13 of the second pre-perforating cylinder pair 9 and the second through-perforating knife cylinder 20-2 is attached to the groove cylinder 13 of the second through-perforating cylinder pair 11, while the first cross-cutting device 4 is deactivated, so that signatures 3 with a second section length L2 are produced.

[0049] To change the signatures 3 from the second section length L2 to the first section length L1, only the second cross-cutting device 5 needs to be deactivated and the first cross-cutting device 4 activated. Deactivation can be done, for example, as described below. Fig. 2 The described procedure is carried out, but applied to the respective pre-perforating cylinder pair 8, 9 and to the respective through-perforating cylinder pair 10, 11.

[0050] Fig. 4 shows a further embodiment of a cross-cutting unit 1, which in its basic structure is a variation of the one in Fig. 3 The depicted version represents the fundamental components and their functions, which is why they also apply to the one in Fig. 4 The variant shown is valid.

[0051] In contrast to the one in Fig. 3 The depicted version is in the Fig. 4 In the variant shown, viewed in the direction of travel LR, the first pre-perforating cylinder pair 8 is arranged upstream of the second pre-perforating cylinder pair 9, and the first through-perforating cylinder pair 10 and the second through-perforating cylinder pair 11 are arranged downstream of the second pre-perforating cylinder pair 9.

[0052] Furthermore, viewed in the direction of travel LR, the first pair of perforating cylinders 10 is arranged upstream of the second pair of perforating cylinders 11.

[0053] The first pre-perforating cylinder pair 8 comprises the first pre-perforating knife cylinder 19-1 and a slotting cylinder 13 with a first section length L1. The second pre-perforating cylinder pair 9 comprises the second pre-perforating knife cylinder 19-2 and a slotting cylinder 13 with a second section length L2. Furthermore, the first through-perforating cylinder pair 10 comprises the first through-perforating knife cylinder 20-1 and a slotting cylinder 13 with a first section length L1. The second through-perforating cylinder pair 11 comprises the second through-perforating knife cylinder 20-2 and a slotting cylinder 13 with a second section length L2.

[0054] Even in the Fig. 4In the illustrated example, the first cross-cutting device 4 with the first section length L1 is again deactivated, so that the first pre-perforating cylinder pair 8 and the first through-perforating cylinder pair 10 are deactivated and thus disconnected from the strand 2. A strand 2 pre-perforated by the first pre-perforating cylinder pair 9 is consequently guided past the deactivated and disconnected first through-perforating cylinder pair 10 and cut off by the second through-perforating cylinder pair 11.

[0055] Although in Fig. 4 For the sake of clarity, the transport system 16 that is possible or required for this design is not shown, but Fig. 5 a side view of the in Fig. 4 the illustrated design, wherein in Fig. 5Only the side with the pre-perforating cylinders 19 and the perforating cylinders 20 is shown for each pair of pre-perforating cylinders 8, 9 and for each pair of through-perforating cylinders 10, 11.

[0056] Fig. 5 Thus, viewed in the direction of travel LR of strand 2, the first pre-perforating cylinder pair 8 with the first pre-perforating knife cylinder 19-1, the second pre-perforating cylinder pair 9 with the second pre-perforating knife cylinder 19-2, the first through-perforating cylinder pair 10 with the first through-perforating knife cylinder 20-1 and the second through-perforating cylinder pair 11 with the second through-perforating knife cylinder 20-2.

[0057] Furthermore, it shows Fig. 5The transport system 16a is designed for the first pre-perforating cylinder pair 8 and the second pre-perforating cylinder pair 9. The transport system 16a is configured as a conveyor belt with several conveyor belts arranged side by side, which extend across the width of the strand 2 at the points where the strand 2 is not pre-perforated by the pre-perforating knife cylinders 19. Since the first pre-perforating cylinder pair 8 and the second pre-perforating cylinder pair 9 are arranged downstream in the direction of travel LR and are directly adjacent to each other, the upper transport system 16a can be used for both the first pre-perforating cylinder pair 8 and the second pre-perforating cylinder pair 9.

[0058] Furthermore, it shows Fig. 5The transport system 16b is designed for the first pair of perforating cylinders 10 and the second pair of perforating cylinders 11. The transport system 16b is configured as a conveyor belt with several conveyor belts arranged side by side, which extend across the width of the strand 2 at the points where the strand 2 is not cut by the perforating cylinders 20. Since the first pair of perforating cylinders 10 and the second pair of perforating cylinders 11 are arranged downstream in the direction of travel LR and are directly adjacent to each other, the lower transport system 16b can be used for both the first pair of perforating cylinders 10 and the second pair of perforating cylinders 11.

[0059] The two transport systems 16 will be used in the Fig. 5 The illustrated example consists of motor-driven drive rollers 21 and includes a plurality of guide rollers 22 for guiding the conveyor belts.

[0060] Although in the Figures 2 to 5 While only examples with a first cross-cutting device 4 in a first section length L1 and a second cross-cutting device with a second section length L2 are shown, it is of course also possible to design a cross-cutting unit 1 with more than two cross-cutting devices in order to be able to selectively realize more than two different section lengths L.

[0061] Although in the Figures 2 to 4 Since only examples have been shown and described in which the transverse cutting devices 4, 5 have only the speed of the strand 2 as their circumferential speed, it is also possible to realize the section lengths L by changing the circumferential speeds of the transverse cutting devices 4, 5. Reference symbol list

[0062] 1 Cross-cutting unit 2 Strand 3 Signature 4 First cross-cutting unit 5 Second cross-cutting unit 6 First pair of cutting cylinders 7 Second pair of cutting cylinders 8 First pair of pre-perforating cylinders 9 Second pair of pre-perforating cylinders 10 First pair of through-perforating cylinders 11 Second pair of through-perforating cylinders 12 Knife cylinder 13 Grooving cylinder 14 Infeed conveyor 15 Outfeed conveyor 16 Transport system 17 Cutting knife 18 Cutting strip 19 Perforating knife cylinder 20 Through-perforating knife cylinder 21 Drive roller 22 Guide roller LR Direction of travel L Section length L1 First section length L2 Second section length

Claims

1. Cross-cutting unit (1) for a folding unit for format-variable cutting of a folded or unfolded strand (2) running with a direction LR into a plurality of signatures (3), comprising a first cross-cutting device (4) for separating signatures (3) from the strand (2) with a first section length L1 and a second cross-cutting device (5) for separating signatures (3) from the strand (2) with a second section length L2. characterized by the fact that the first cross-cutting device (4) is arranged upstream of the second cross-cutting device (5) in the direction of travel LR and wherein the first cross-cutting device (4) and the second cross-cutting device (5) can be activated alternately.

2. Cross-cutting unit (1) according to claim 1, characterized by the fact thatthe first transverse cutting device (4) comprises a first cutting cylinder pair (6) comprising a first knife cylinder (12-1) and a first groove cylinder (13-1) for single-cutting of the strand (2).

3. Cross-cutting unit (1) according to one of claims 1 or 2, characterized by the fact that the second transverse cutting device (5) comprises a second pair of cutting cylinders (7) comprising a second knife cylinder (12-2) and a second groove cylinder (13-2) for single-cutting of the strand (2).

4. Cross-cutting unit (1) according to claim 2, characterized by the fact that In the direction of travel LR of the strand (2) seen upstream of the first cross-cutting device (4) a first inlet conveyor line (14-1) and downstream of the first cross-cutting device (4) a first outlet conveyor line (15-1) is arranged.

5. Cross-cutting unit (1) according to claim 3, characterized by the fact thatIn the direction of travel LR of the strand (2) seen upstream of the second cross-cutting device (5) a second inlet conveyor line (14-2) and downstream of the second cross-cutting device (5) a second outlet conveyor line (15-2) is arranged.

6. Cross-cutting unit (1) according to one of claims 1, 3 or 5, characterized by the fact that the first transverse cutting device (4) comprises a first pre-perforating cylinder pair (8) and a first through-perforating cylinder pair (10) arranged downstream of it in the direction of travel LR.

7. Cross-cutting unit (1) according to one of claims 1, 2, 4 or 6, characterized by the fact that the second transverse cutting device (5) comprises a second pre-perforating cylinder pair (9) and a second through-perforating cylinder pair (11) arranged downstream of it in the direction of travel LR.

8. Cross-cutting unit (1) according to one of claims 6 or 7, characterized by the fact thatViewed in the direction of travel LR, the first pre-perforating cylinder pair (8) is arranged upstream of the second pre-perforating cylinder pair (9) and the first through-perforating cylinder pair (10) and the second through-perforating cylinder pair (11) are arranged downstream of the second pre-perforating cylinder pair (9).

9. Cross-cutting unit (1) according to claim 8, characterized by the fact that Viewed in the direction of travel LR, the first pair of perforating cylinders (10) is arranged upstream of the second pair of perforating cylinders (11).

10. Cross-cutting unit (1) according to any one of claims 1 to 9, characterized by the fact that the first cross-cutting device (4) has a first circumference U1 which corresponds to the first section length L1 or an even multiple of the first section length L1.

11. Cross-cutting unit (1) according to any one of claims 1 to 10, characterized by the fact thatthe second transverse cutting device (5) has a second circumference U2 which corresponds to the second section length L2 or an even multiple of the second section length L2.

12. Folding unit for separating a folded or unfolded strand (2) running in with a direction LR into a plurality of signatures (3) with a first section length L1 or a second section length L2, characterized by the fact that the folding unit comprises a cross-cutting unit (1) according to one of claims 1 to 11.

13. Method for format-variable cutting of a folded or unfolded strand (2) running with a direction LR into a plurality of signatures (3) by means of a cross-cutting unit (1), wherein the strand (2) is cut either with a first cross-cutting device (4) for separating signatures (3) from the strand (2) with a first section length L1 or with a second cross-cutting device (5) for separating signatures (3) from the strand (2) with a second section length L2, characterized by the fact thatThe strand (2) is either cut by the first cross-cutting device (4) in signatures (3) of the first section length L1 and the second cross-cutting device (5) is passed through without cutting by the signatures (3) with the first section length L1 or the first cross-cutting device (4) is passed through without cutting by the strand (2) and the strand (2) is cut by the second cross-cutting device (5) in signatures (3) with the second section length L2.

14. Method according to claim 13, characterized by the fact that the cross-cutting unit (1) is designed according to one of claims 1 to 11.

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