DE29903677U1 - Cross cutting device - Google Patents

Description

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Maschinenfabrik Ravenstein GmbH, Eichenstr. 23, 74747 Ravenstein

Cross cutting device

The invention relates to a cross-cutting device for cutting single- or multi-layered material webs, in particular made of paper material, with at least one knife carrier which carries at least one cutting knife which has at least one cutting section extending transversely to the conveying direction of the material web to be cut, which is brought into and out of cutting engagement with the material web by the moving knife carrier.

Cross-cutting devices of this type are used in particular in so-called in-line or off-line finishing systems, in which printed material webs made of paper material are further processed into intermediate products or end products such as catalogs, brochures, advertising brochures, etc. In the cross-cutting device, the mostly multi-layered material web is cut to length in sections, with the cut sections corresponding to the individual pages of the aforementioned printed products, which are then stapled, glued or otherwise

be processed in a manner.

The cross-cutting devices used to date have a roller-like knife carrier that carries one or more 1 iron-shaped cutting knives on its circumference, which cut through the assigned material web in a punch-like process when the knife carrier rotates. In order to achieve a clean cut, however, the thickness of the material web that can be cut is limited to a certain extent. This means that thicker printed products made up of a large number of layers cannot be cut all at once. In these cases, thinner material stacks are cut first, which are then combined in the correct order, which means a not inconsiderable additional processing effort.

It is therefore the object of the present invention to create a cross-cutting device that allows clean lengthwise cutting of even thicker and in particular multi-layered material webs.

To solve this problem, the cutting blade is designed as a self-contained endless band blade that is wound around deflection rollers mounted on the blade carrier and is positioned relative to the blade carrier to form a

can be driven by a cutting movement rotating around the deflection rollers, and that the knife carrier can be driven during the cutting process to move along a cutting path in a feed movement that moves with the conveyed material web.

In this way, the material web is no longer cut through by a single impact cut. The cutting process is more dependent on the driven cutting movement of the cutting knife relative to the knife carrier, which cuts through the material web gradually. In order to be able to cut material webs of greater thickness, the knife carrier is moved along with the material web for a certain distance during the cutting process. In this way, there is sufficient time to cut through the material web. Even with multi-layer material webs, i.e. material webs that consist of a large number of individual layers on top of each other, a very precise and clean cutting pattern can be achieved. The greater maximum cutting thickness compared to the state of the art also allows thicker material stacks and thus thicker printed products to be cut, so that in many cases the subsequent merging of separately cut thinner partial stacks can be dispensed with. The entire finishing process can be shortened and simplified.

Advantageous further developments of the invention emerge from the subclaims.

The circular cutting movement of the band knife could in principle be caused by a drive device provided on the knife carrier and moving with the knife carrier, which draws its drive energy from moving fluid or electrical cables or from electrical sliding contacts. However, a considerably more advantageous and simpler embodiment is one in which the cutting movement of the band knife is derived from the feed movement of the knife carrier, so that the knife carrier itself does not have to be equipped with a drive device operated by external energy. A drive wheel arranged on the side of the knife carrier and coupled to the band knife in terms of drive has proven to be very reliable. This drive wheel runs on a fixed rolling section to generate the cutting movement while running through the cutting section. The drive wheel is preferably designed as a gear wheel and the rolling section as a linear toothing with which the drive wheel meshes.

In order to achieve a particularly precise cutting process, it is recommended that the knife carrier is held securely on a linear guide at least when passing through the cutting section.

This also has the advantage that a transport device that causes the knife carrier to move does not have to meet particularly high requirements in terms of guide accuracy, which allows for more cost-effective production.

The rolling section and the longitudinal guide are conveniently arranged parallel to each other. This means that the knife carrier can be guided and the circulating drive of the spring-elastic band knife can be implemented in the smallest of spaces.

Preferably, the design is such that the band knife penetrates into the material web with increasing cutting depth during the feed movement of the knife carrier during the cutting process. This prevents overloading of the band knife and damage to the material web. The cutting progress can be very easily adapted to the requirements of the material to be cut.

If there are several knife carriers that pass through the cutting section at different times, the working speed of the cross-cutting device can be increased significantly.

The cross-cutting device can be sharpened

station in which the band knives can be resharpened without having to dismantle them. The downtime of the device can thus be reduced considerably.

The band knife expediently has two cutting sections extending next to each other across the feed direction of the knife carrier, which are expediently formed by two strands of the rotating band knife and which move in opposite directions. This makes it possible to make two spaced cuts simultaneously in a single cutting process. This feature is particularly useful for cutting out the unprinted areas of a material web that occur due to the structure of a printing roller. If an adjustment device is available for variable specification of the distance between the two cutting sections, an adjustment can be made to suit the respective application.

If only one cut is to be made per cutting process, the band knife is best guided so that only one effective cutting section is available. Guide means can be provided which change the alignment of one of the two cutting sections so that it is always kept out of engagement with the material web while it is running through the cutting section.

The invention is described below with reference to the attached
Drawing explains in more detail. In this show:

Fig. 1 shows a first design of the cross-cutting device according to the invention in a schematic side view
and partly in longitudinal section according to
Section line II from Fig. 4,

Fig. 2 is a plan view of the cross-cutting device according to Fig. 1, looking in the direction of arrow II, limited to the area of the knife carrier,
where the band knife located below the knife carrier is indicated by dashed lines,

Fig. 3 a cross section through the knife carrier according to section line III-III from Fig. 4 in the area of one end of the knife carrier, where a drive wheel and reversing rollers for the band knife can be seen,

Fig. 4 a partial representation of the cross-cutting device from Fig. 1 in cross section according to section line IV-IV,

Fig.5

and 6 cross sections through the knife carrier according to

Section line V-V from Fig. 4, where guide means

are visible, which engage one of the cutting sections of the band knife in order to hold it in a different orientation, and

Fig. 7 shows a section of the cross-cutting device from Fig. 1 with a view according to arrow VII to a sharpening station only indicated schematically in Fig. 1.

The example cross-cutting device 1 has a cross-cutting station 2 and a sharpening station 3, which is only indicated by a dot-dash line in Fig. 1. The cross-cutting station 2 has a feed side 4 and a removal side 5 opposite it. During operation, a single- or multi-layered material web 6, shown in simplified form, is fed to the sharpening station 3 via the feed side 4, which then passes through the cross-cutting station 2 with the web plane aligned horizontally. When passing through the cross-cutting station 2, the material web 6 is cut transversely at longitudinal intervals, so that cut web sections 7 emerge from the removal side 5 and can be removed.

The material web 6 is originally present as a coil-like winding body 8, which is schematically indicated in Fig. 1

The unwound section of the material web 6 passes, for example, through a printing machine in which it is printed in a suitable manner in order to produce a printed product in the form of a brochure or a catalog or the like.

Additional material webs, which are not shown in detail here, can be provided and printed in parallel. After passing through the printing machine, they can be brought together in the correct order so that ultimately there is a material web that is made up of several individual webs lying on top of each other and can therefore be referred to as a multi-layer material web 6. The example shows such a multi-layer material web 6. Following the printing machine (not shown), it passes through a so-called in-line finishing system in which so-called finishing processes such as gluing, cutting, punching or other post-processing are carried out. The cross-cutting device 1 according to the example is a component of such a finishing system, which can also be designed as an offline finishing system and is operated independently of an associated printing machine.

The cross-cutting device 1 has a conveyor

device 12, with the help of which the material web 6, which is usually made of paper material, and the cut web sections 7 are conveyed through the cross-cutting device 1. The exemplary conveying device 12 has two deflection rollers 13, 13' arranged at a distance from one another, at least one of which is rotationally driven and around which a conveyor belt 14 is wound. The upper run of the conveyor belt 14 defines a horizontally aligned conveying plane 15 on its upwardly facing outer side, on which the material web 6 is displaced in the longitudinal direction with the web plane 16 also aligned horizontally.

At a distance above the conveyor level 15, a transport device generally designated 17 is provided, which serves to transport, for example, two knife carriers 18. One of these knife carriers 18 is only indicated schematically in Fig. 1. During transport, the knife carriers 18 pass through a self-contained transport path 21, which has a path section above the conveyor level 15 that runs essentially in the direction of the conveying direction 22 of the material web 6 and is designated as a cutting path 23. The cutting path 23 extends essentially between the loading side 4 and the removal side 5.

When passing through the cutting section 23, a respective knife carrier 18 carries out a linear feed movement, whereby it moves at the same speed as the material web 6. When passing through the cutting section 23, a respective knife carrier 18 is thus driven to a feed movement that moves along with the conveyed material web 6.

A cutting knife is arranged on each knife carrier 18, which is designed as a self-contained endless band knife 24. This band knife 24 is wound around deflection rollers 25 that are rotatably mounted on the knife carrier 18 and can be driven relative to the knife carrier to perform a cutting movement 26 that revolves around the deflection rollers 25. At least one and possibly two cutting sections 27, 27' formed by length sections of the band knife 24, which extend parallel to the conveying plane 15 transversely and in particular at right angles to the conveying direction 22, act on the material web 6 as it passes through the cutting section 23 and cut it in the transverse direction. In this case, the cutting sections 27, 27' gradually come into cutting engagement with the material web 6, starting from the area of the feeding side 4, in order to come out of cutting engagement again after the cutting has been completed in the area of the removal side 5.

The transport device 17, which is present above the conveyor device 12, has in the area of the loading side 4 and

in the area of the removal side 5 there are two pairs of deflection rollers 28, 28' arranged at a transverse distance from one another. In Fig. 1 only one of the front and rear deflection rollers 28, 28' is visible; they cover the other two deflection rollers. A transversely flexible transport strand 32, 32' is wound around each front deflection roller 28 and the rear deflection roller 28' opposite it in the conveying direction 22. This is formed, for example, by a transport chain, the deflection rollers 28, 28' being designed like gears which engage positively in the transport chain. The deflection rollers 28, 28' are arranged in such a way that the two transport strands 32, 32' come to lie in the area of the two long sides of the cross-cutting device 1. The deflection rollers 28, 28' on both sides are synchronized in pairs, for example by a connecting shaft 33, and at least one of the deflection roller pairs is coupled to a drive device 34, formed for example by an electric drive motor, which provides the rotary drive and is ultimately responsible for the reversing movement of the knife carriers 18 along the transport path 21. A respective knife carrier 18 is simultaneously suspended on both transport strands 32, 32', whereby it extends between them in a web-like manner according to Fig. 2. The

Knife carrier 18 has a head 36, 36' on each of its front sides, which is secured to the associated transport line 32, 32' via suitable suspension means 35. The two heads 36, 36' are rigidly connected to one another via a connecting strut 37 running transversely to the conveying direction 22.

In order to achieve a precise cutting process, each knife carrier 18 is guided longitudinally on a linear guide 42 that determines the direction of its feed movement 38 when it passes through the cutting section 23. Outside the cutting section 23, special guidance of the knife carrier 18 is not required, so that particularly precise guide devices can be dispensed with there. For example, it is provided that the knife carriers 18 are coupled to the linear guide 42 when entering the cutting section and are disengaged from the linear guide 42 when leaving the cutting section 23. This happens automatically because the linear guide 42 is suitably aligned with respect to the transport path 21.

The linear guide 42 of the embodiment has two guide rails 43 arranged transversely to one another with respect to the conveying direction 22 of the material web 6. They are located, for example, approximately below the respective

Pair of deflection rollers 28, 28' arranged longitudinally of the transport device 17, wherein they are expediently located horizontally opposite one another.

A guide shoe 44 is arranged on each of the two heads 36, 36' of the knife carrier 18, which can come into guide engagement with the associated guide rail 43 according to Fig. 1 and 2 and is then guided longitudinally on the guide rail 43. In the embodiment, a respective guide shoe 44 has a cross-section that is somewhat like a clamp and, when in guide engagement, can grip around a strip-like guide section 45 of the relevant guide rail 43. It can be a sliding guide or, preferably, as shown, a roller guide. Such linear guides are, as such, state of the art and therefore do not require any further explanation.

The input-side end 46 of a respective guide rail 43 assigned to the feed side 4 can be designed in such a way that the slide-like guide shoe 44 can easily be threaded into or onto the desired guide contact. For example, the guide rail 43 can taper off at the end section 46.

For example, on the two transport lines 32, 32'

according to two knife carriers 18 are arranged, which are arranged at a distance from one another in the longitudinal direction of the transport path 21 and therefore pass through the cutting section 23 one after the other. An even larger number of knife carriers 18 could also be provided on the transport device 17. With several knife carriers 18, the working speed can be increased because a knife carrier can enter the cutting section 23 even when the preceding knife carrier 18 is still within the cutting section 23 or is just about to leave the cutting section. A continuous, stop-free operation of the cross-cutting device 1 is thus guaranteed.

It is advisable to arrange the arrangement in such a way that the band knife 24 gradually approaches the conveyor plane 15 as it passes through the cutting section 23 and thus penetrates into the material web 6 with increasing cutting depth. The band knife 24 does not immediately bear against the material web 6 with full pressure, but is immersed in the material web 6 as the cutting process progresses. This protects the band knife and ensures clean cutting edges on the cut web sections 7.

The movement of the respective cutting section 27, 27'

of the band knife 24 in the cutting depth direction could, for example, be achieved by equipping the knife carrier 18 with a suitable cutting depth setting device that is able to displace the band knife 24 in the cutting depth direction 47, at least in the area of its cutting sections 27, 27' relative to the knife carrier 18. However, a design in which the entire knife carrier 18 carries out the displacement in the cutting depth direction 47 is considerably simpler. This is implemented in the exemplary embodiment. Here, the linear guide or its guide rails 43 are arranged so as to be slightly inclined with respect to the conveying plane 15 that the feed direction 38 of the knife carrier 18 runs at a slight acute angle to the conveying direction 22 when passing through the cutting section 23. This acute angle is indicated in Fig. 1 at 48. The guide rails 43 are arranged here at their input-side end section 46 with a slightly greater distance from the conveying plane 15 than in the area of their opposite output-side end section 46'.

A preferred possibility for holding the band knife 24, which is usually made of spring-elastic metal material, is shown in Figs. 3 and 4. The bearing on one of the heads 36 is shown here, whereby the bearing on the opposite head 36' is expediently

is designed accordingly

On the underside of each head 36 there is an arrangement of, for example, five deflection rollers 25 which are rotatably mounted on or in the head via bearing axes 52. The axes of rotation of the deflection rollers 25 are, when viewed through the cutting section 23, aligned at right angles to the conveying plane 15 or to the imaginary inclined plane 53 which runs parallel to the direction of the feed movement 38. In each case there is an outer central deflection roller 25, 25', which is followed, towards the connecting strut 37, by two pairs of further deflection rollers 25, 25''; 25, 25 ¹¹¹ , which are arranged at a distance on both sides of an imaginary linear connecting line 54 which connects the axes of rotation of the outer central deflection rollers 25, 25' of the two heads 36, 36'.

The flexible band knife is guided around the respective central deflection roller on the outside opposite the other deflection rollers 25' ', 25''■, whereby the two strands adjoining this central deflection roller 25' initially move apart in order to approach each other again after an outer circuit around the adjoining pair of deflection rollers 25, 25'' and to be guided past the facing inner roller surfaces 55 of the further pair of deflection rollers 25, 25' ''.

The band knife 24 thus runs past the first pair of further deflection rollers 25, 25'' on opposing outer roller surfaces and then between the two deflection rollers 25, 25'' of the second deflection roller pair.

The two cutting sections 27, 27' already mentioned are formed by the two sections of the two strands 56, 56' of the band knife 24, which are connected to the pairs of idler pulleys 25, 25' '' that have passed the roller surfaces 55 facing each other and, as they pass through the cutting section 23, span it at a distance above it.

In order to generate the cutting movement 26 of the band knife 24 mentioned at the beginning, at least one of the deflection rollers 25 is rotationally driven. Its rotation is transmitted in particular by frictional engagement to the adjacent band knife 24, whereby one or more additional pressure rollers can also be present to support the frictional connection. For example, one of the outer central deflection rollers 25, 25' is rotationally driven, for which purpose it is in drive connection with a drive wheel 57, which is, for example, mounted in a rotationally fixed manner on the bearing axis 52 connected to the deflection roller 25, 25'. The drive wheel 57 is, for example, designed as

Gear wheel executed.

In the area of the cutting section 2 3 , next to one of the guide rails 43 , a rolling section 58 is provided which runs parallel to this, the length of which can be approximately the same as that of the adjacent guide rail 43 . The rolling section 58 is expediently formed by a rack 59 which has a linear toothing 6 2 , the teeth of which are arranged one after the other in the longitudinal direction. The linear toothing 62 faces the knife carrier 18 which is moving past.

When the knife carrier 18 runs through the cutting section 23, whereby it is guided on the linear guide 42, the toothed drive wheel 57 is in meshing engagement with the linear toothing 62 and runs along it. Since the linear toothing 62 is arranged in a fixed position, the drive wheel 57 has a rotational movement derived from the feed movement 38 of the knife carrier 18, which causes the cutting movement 26 of the band knife 24. In this way, a separate drive device is not required on the respective knife carrier 18, which would have to be supplied with drive energy from the outside, which would be expensive.

The drive wheel 57 could, for example, also be designed as a friction wheel that is mounted on a flat rolling track 58

However, an at least partially positive drive contact as in the example ensures a safer transmission of the drive force under all circumstances.

The coupling between the drive wheel 57 and the rolling track 58 preferably takes place simultaneously or slightly after the production of the guide connection in the area of the linear guide 42.

Since a rotary drive of the band knife 24 is not required outside the cutting section 23, the rolling section 58 can remain limited to the area of the cutting section 23.

By suitably arranging the deflection rollers 25 assigned to the band knife 24 and/or by using additional guide means, the band knife 24 can easily be guided in such a way that only one cutting section 27 can come into engagement with the material web 6 when passing through the cutting section 23. The cross-cutting device 1 according to the example is, however, equipped in such a way that either a single cut with one cutting section 27 or a simultaneous double cut with two cutting sections 27, 27' running parallel to one another can be carried out.

Fig. 2, 3 and 5 show the setting of the band knife 24 for a double cut. Here, the two cutting sections 27, 27' mentioned above each run at a right angle to the feed direction 38 with a certain cutting distance s measured in the feed direction 38. The knife planes in the area of the cutting sections 27, 27' are aligned parallel to each other and extend at a right angle to the conveyor plane 15 when running through the cutting section 23. During the cutting process, both cutting sections 27, 27' thus come into engagement with the material web 6 so that a transverse web strip of width s is cut out of it. This makes it very easy to cut printed material webs 6 to length and at the same time cut out an unprinted gap caused by the design of the printing machine. Subsequent edge trimming can therefore be omitted. Since the band knife 24 has opposite running directions in the area of the cutting sections 27, 27' due to its unidirectional revolving movement, a very precise cutting process is always possible.

The distance s between the two cutting sections 27, 27' can be conveniently adjusted to be variable in order to be able to adapt to different print images on the material web to be cut. The two

The cross-cutting device 1 according to the play therefore has a corresponding adjustment device 63 which is arranged on the two heads 36, 36' of the knife carrier 18. Components of this adjustment device 63 are the two deflection rollers 25, 25 ^' , which the band knife 24 passes on their mutually facing roller surfaces 55, which can therefore be referred to as adjustment rollers 64. These adjustment rollers 64 are mounted on the knife carrier 18 in such a way that at least one and preferably both adjustment rollers 64 can be adjusted in and against the feed direction 38 according to double arrows 65 and can be releasably fixed in the adjusted position. For this purpose, Fig. 4 shows a slide 66 which carries the bearing axis 52 of an adjusting roller 64, via which the adjusting roller 64 is slidably mounted on the associated head 36, wherein a locking screw 67 enables a desired positioning.

At least one cutting section 27' is assigned guide means 68 in the area between the two heads 36, 36', which make it possible to align the relevant cutting section 27' so that it always remains out of engagement with the material web 6 while it is running through the cutting section 23. The guide means 68 according to the example are adjustably arranged on a holding part 39 carried by the connecting strut 37. They surround the relevant cutting section 27' on both sides and allow

pivot according to double arrow 73 so that the cutting section 27 ^' is rotated about its longitudinal axis and assumes the ineffective orientation shown in Fig. 6, in which it is arranged at a distance from the material web 6 when passing through the cutting section 23 and runs approximately parallel to it. The guide means 68 can be formed by guide rollers. The adjustment movement can be implemented, for example, by a circular arc guide. Both the effective orientation according to Fig. 5 and the ineffective orientation according to Fig. 6 of the cutting section 27' can be releasably fixed, which can be done, for example, using a locking screw 74. As a further equipment detail, the exemplary cross-cutting device 1 has a sharpening station 3 located outside the cutting section 23. It is located, for example, in the area of the transport path 21 through which a knife carrier 18 passes when it is in the area of the upper strands of the transport strands 32, 32'. Here, the knife carrier 18 is arranged upside down so that the cutting edge 72 of the band knife 24 projects upwards and is particularly easily accessible for resharpening.

According to Fig. 7, a sharpening device 74 is arranged in the sharpening station, which has a sharpening body 75, for example a suitable grindstone,

which can be moved according to the double arrow 76 between an ineffective position shown in solid lines and an effective position (indicated by dash-dotted lines) adjacent to the cutting edge 72 of the band knife 24 positioned opposite below.

In addition, the sharpening station 3 has a drive device 77, which is normally disengaged from the drive wheel 57 of the knife carrier 18 and can be moved if necessary into a drive position 78 indicated by a dash-dotted line, in which it engages the drive wheel 57 with a rotary gear 79. Coupled in this way to the drive wheel 57, the band knife 24 can be driven outside the cutting section 23 to its circular cutting movement by actuating the drive device 77, whereby it is sharpened by the sharpening body 75, which is simultaneously moved into the active position.

The sharpening station 3 can also be designed so that the sharpening process takes place during the uninterrupted rotation of the knife carrier 18. For this purpose, for example, the rotation of the band knife 24 could be derived from the rotation of the knife carrier 18, comparable to the drive within the cutting section 23, and the sharpening device 74 could be moved along with it.

be arranged on the knife carrier 18.

The cutting edge 72 of the band knife can be straight or contoured with successive elevations and depressions, the corresponding selection being made in particular depending on the material to be cut.

The cuttable material web, which is severed by the band knife 24 in the thickness direction, can also consist of material other than paper material, for example of plastic material in the form of a film.

Claims (19)

:G -1.871AtP..-: leno 01. March 1999 Maschinenfabrik Ravenstein GmbH, Eichenstr. 23, 74747Ravenstein &eegr; Cross-section &ngr;&ogr; r directionAppeals 1. Cross-cutting device for cutting single- or multi-layered bales of material (6), in particular made of paper material, with at least one knife carrier (18) which carries at least one cutting knife which has at least one cutting section (27, 27') extending transversely to the conveying direction (22) of the material web (6) to be cut, which is brought into and out of cutting engagement with the material web (6) by the moving knife carrier (18), characterized in that the cutting knife is designed as a self-contained endless band knife (24) which is wound around deflection rollers (25) mounted on the knife carrier (18) and can be driven relative to the knife carrier (18) to perform a cutting movement (26) revolving around the deflection rollers (25), and that the knife carrier (18) can be moved during the cutting process to perform a cutting movement (26) which moves along with the conveyed material web (6). Feed movement (38) along a cutting path (23) can be driven. 2. Cross-cutting device according to claim 1, characterized in that the cutting movement (26) of the band knife (24) is derived from the feed movement (38) of the knife carrier (18). 3. Cross-cutting device according to claim 2, characterized in that the band knife (24) is in drive connection with a drive wheel (57) provided on the knife carrier (18), which runs on a stationary rolling track (58) to generate the cutting movement during the feed movement (38) of the knife carrier (18). 4. Cross-cutting device according to claim 3, characterized in that the drive wheel (57) is designed as a gear wheel and the rolling section (58) is designed as a linear toothing (62) provided in particular on a rack. 5. Cross-cutting device according to one of claims 1 to 4, characterized in that the knife carrier (18) is guided so as to be longitudinally movable, at least when passing through the cutting section (23), on a linear guide (42) which determines the direction of the feed movement (38). 6. Cross-cutting device according to claim 5, characterized in that the linear guide (42) has two with respect to the conveying direction (22) of the material web (6) with cross- spaced apart guide rails (43) on which the knife carrier (18) is displaceably guided by a guide shoe (44). 7. Cross-cutting device according to claim 5 or 6 in connection with claim 3 or 4, characterized in that the rolling path (58) and the linear guide (42) run parallel to one another. 8. Cross-cutting device according to one of claims 1 to 7, characterized in that the band knife (24) penetrates into the material web (6) with increasing cutting depth during the feed movement (38) of the knife carrier (18) taking place during the cutting process. 9. Cross-cutting device according to one of claims 1 to 8, characterized in that the feed direction (38) of the knife carrier (18) runs at a slight acute angle to the plane (16) of the adjacent material web (6) when passing through the cutting section (23), such that the knife carrier (18) gradually approaches the material web (6) during the feed movement (38) and the band knife (24) penetrates into the material web (6) with increasing cutting depth. 10. Cross-cutting device according to one of claims 1 to 9, characterized in that the knife carrier (18) in operation carries out a circular movement along a self-contained transport path (21), the feed movement (38) being part of the circular movement. 11. Cross-cutting device according to claim 10, characterized in that the knife carrier (18) is held on at least one transport line (32, 32') of a driven transport device (17) running around deflection rollers (28, 28'), for example formed by a transport chain. 12. Cross-cutting device according to claim 11, characterized in that several knife carriers (18) are arranged at a distance from one another on the at least one transport line (32, 32'), which knife carriers (18) pass through the cutting section (23) one after the other during operation. 13. Cross-cutting device according to one of claims 1 to 12, characterized in that a sharpening station (3) is present in which the band knife (24) can be resharpened. 14. Cross-cutting device according to claim 13, characterized in that the sharpening station (3) has a drive device (77) which is connected to the belt knife (24) can be coupled in a drive-related manner, that this can be driven to a revolving movement corresponding to the cutting movement, and that a sharpening device (74) is provided which can be brought into engagement with the cutting edge (72) of the band knife (24) driven in this way. 15. Cross-cutting device according to one of claims 1 to 14, characterized in that the band knife (24) has two cutting sections (27, 27') extending next to one another transversely to the feed direction (38) of the knife carrier (18), which are expediently formed by two strands of the rotating band knife (24). 16. Cross-cutting device according to claim 15, characterized in that an adjusting device (63) is provided for variably specifying the distance between the two cutting sections (27, 27'). 17. Cross-cutting device according to claim 16, characterized in that the adjusting device (63) has deflection rollers (25, 25'') for the band knife (24) whose spacing is adjustable. 18. Cross-cutting device according to one of claims 15 to 17, characterized in that at least one of the cutting sections (27, 27') is assigned guide means (68) which disengage the relevant cutting section {27') during passage through the cutting section (23)
with the material web (6). 19. Cross-cutting device according to one of the claims
1 to 18, characterized in that the band knife (24) cuts the material web (6) in the direction of its thickness during the cutting process.