EP0808698A2 - Device and method for cutting paper products fed in a shingled stream - Google Patents

Abstract

The items are delivered in an overlapping stream (17) to the rotary knife (10). The latter is situated below the stream, cutting through it in the upwards direction and against the transport direction. Alternatively it can rotate in this direction, or can be mounted above the stream, cutting from top to bottom. On the opposite side of the stream to the knife there can be an impression knife, typically cylindrical and intermeshing with it. It can have a round body to which a large number of roughly rectangular blades (11) are fixed.

Description

The invention relates to a method for cutting paper products conveyed in a shingled stream with a rotary cutting knife.

Cutting knives for rotary cutting systems are generally known and can be made in one piece or in several parts. DE 37 19 721 C2 describes a multi-part rotary cutting knife which has a round base body, a large number of individual blades or knives being fastened to the outer circumference of the base body. The disclosure of this publication is expressly made the subject of the present application.

Fig. 1 shows a similar rotary cutting knife, as is known from the publication known above in a conventional rotary cutting system. In this case, the rotary cutting knife 10, as has been customary up to now, is used as an upper knife and works together with a counter knife 12, which is also driven and is designed as a lower knife. This counter knife 12 has no individual blades or knives but is essentially designed as a circular cylinder. This counter knife does not cut into the paper, but - like a pair of guillotine shears - forms a shear edge for the upper knife. The bedknife is driven at the same speed as the product flow and moves in the cutting area in the same direction as the product flow. However, fixed counter knives are also known in principle. As the arrows shown in FIG. 1 show, the rotary cutting knife 10, ie the upper knife, rotates counterclockwise, but in the same direction as the product flow 14. The arrangement of the individual knives on the rotary cutting knife 10, that is to say the stepped cutting edge of the rotary cutting knife formed as a result, cuts the product stream according to the scissors-cutting principle, ie the cutting is comparable to cutting a pair of scissors.

Fig. 2 shows an enlargement of the cutting area of Fig. 1, there being a so-called scale jump in the cutting area, i.e. the transition between two products lying on top of one another like a scale. As can be clearly seen from FIG. 2a, a leading product 16 lies flat on a conveying medium in the cutting area, and a following product 18 in turn rests on this leading product 16 in a scale-like manner. This scale jump creates a cavity 20 between the two products 16 and 18, which leads to problems when cutting the scale flow. The individual knife 11 of the rotary cutting knife 10 shown in FIG. 2a penetrates into the flake stream from above during rotary cutting and thereby presses the product 18 on the top onto the product 16 underneath 16 forms, however, so-called crop marks can arise in this area, ie after the cut, tears form in the overhead product, which are created by pressing down the top product 18 by the top rotary cutting knife 10 against the shear edge 21 of the bottom product 16. These cut marks occur in particular in the case of thicker paper products and in particular when the lower product 16 already has a cut side which can form a pronounced shear edge 21.

Fig. 2b illustrates in an enlargement of the Shear edge 21 occurring cutting forces. As can be clearly seen, the resulting cutting force F _{R points} essentially vertically downward and thus causes the upper product 18 to tear at the shear edge 21 of the lower product 16.

It is the problem (object) underlying the invention to eliminate the problems that occur at the scale jump when cutting paper products conveyed in a scale flow.

This object is achieved by the embodiments described and claimed below.

Fig. 1

eine Seitenansicht einer herkömmlichen Rotationsschneidanordnung;

Fig. 2a und 2b

eine Vergrößerung des Schnittbereichs von Fig. 1;

Fig. 3a

eine erste Ausführungsform der Erfindung;

Fig. 3b

eine Querschnittsansicht von Fig. 3a;

Fig. 4a

eine zweite Ausführungsform der Erfindung;

Fig. 4b

eine Querschnittsansicht von Fig. 4a;

Fig. 5a

eine dritte Ausführungsform der Erfindung;

Fig. 5b

eine Querschnittsansicht von Fig. 5a;

Fig. 6a

eine vierte Ausführungsform der Erfindung;

Fig. 6b

eine Querschnittsansicht von Fig. 6a;

Fig. 6c

eine Vergrößerung des in Fig. 6a eingekreisten Schnittbereiches;

Fig. 7a bis 7c

eine fünfte Ausführungsform der Erfindung;

Fig. 8

eine sechste Ausführungsform der Erfindung;

Fig. 9a und 9b

eine Vergrößerung des Schnittbereiches von Fig. 8;

Fig. 10a

eine Darstellung der auftretenden Schnittkraft bei der herkömmlichen Anordnung der Fig. 1 und 2;

Fig. 10b

eine Darstellung der Schnittkraft bei der Anordnung gemäß Fig. 8 und 9;

Fig. 11

eine Seitenansicht einer Rotationsschneidanlage;

Fig. 12

eine Seitenansicht einer weiteren Ausführungsform einer Rotationsschneidanlage;

Fig. 13

eine Draufsicht auf die Rotationsschneidanlage von Fig. 12; und

Fig. 14

die Darstellung eines in beiderlei Drehrichtung verwendbaren Schneidmessers gemäß der Erfindung.

Show it:

Fig. 1

a side view of a conventional rotary cutting assembly;

2a and 2b

an enlargement of the section of Fig. 1;

Fig. 3a

a first embodiment of the invention;

Fig. 3b

a cross-sectional view of Fig. 3a;

Fig. 4a

a second embodiment of the invention;

Fig. 4b

a cross-sectional view of Fig. 4a;

Fig. 5a

a third embodiment of the invention;

Fig. 5b

a cross-sectional view of Fig. 5a;

Fig. 6a

a fourth embodiment of the invention;

Fig. 6b

a cross-sectional view of Fig. 6a;

Fig. 6c

an enlargement of the cutting area encircled in FIG. 6a;

7a to 7c

a fifth embodiment of the invention;

Fig. 8

a sixth embodiment of the invention;

9a and 9b

an enlargement of the cutting area of Fig. 8;

Fig. 10a

a representation of the cutting force occurring in the conventional arrangement of Figures 1 and 2.

Fig. 10b

a representation of the cutting force in the arrangement of FIGS. 8 and 9;

Fig. 11

a side view of a rotary cutting system;

Fig. 12

a side view of another embodiment of a rotary cutting system;

Fig. 13

a plan view of the rotary cutting system of Fig. 12; and

Fig. 14

the representation of a cutting knife usable in both directions of rotation according to the invention.

3a shows a first embodiment of the invention, in which a conventional rotary cutting knife with individual blades 11 is used as the upper knife 10, which rotates in the cutting area in the conveying direction of a scale flow 17 with a positive scale. A rotary cutting knife with individual blades 11 ′ is also provided as the lower knife 12, but rotates in the opposite direction to the conveying direction of the scale flow 17. The lower knife 12 can be ground on the conical side, as a result of which the scale 17 can be cut from below by approximately 20 to 40% in order to avoid tearing at the scale jump. 3b shows that the upper knife 10 is oriented with its product side towards the scale flow, whereas the lower knife 12 is oriented with its product side towards the product side of the upper knife 10. As can be clearly seen, the lower knife 12 cuts the shingled stream 17 from below by approximately 25% and acts together with the upper knife 10 like scissors, i.e. the respective flat sides of the two knives touch each other. In this embodiment, conventional rotary cutting knives, the manufacture and handling of which are known, can be used in an advantageous manner.

4a shows a further embodiment of the invention, in which a conventional rotary cutting knife with individual blades 11 is used as the upper knife 10, which moves in the cutting area in the same direction as the scale flow 17. A counterpressure roller 9, which is arranged below the upper knife and below the positive scale flow 17, interacts with the upper knife 10 and supports the scale flow from below when cutting through the upper knife 10.

In the conveying direction in front of the upper rotary cutting knife 10, a lower knife 12 is provided, which, however, does not act as a counter knife to the upper knife 10, but which cooperates with a counterpressure roller 13 arranged above the scale stream 17. Here, the lower rotary cutting knife 12 rotates in its cutting area counter to the conveying direction of the scale flow 17. Both the upper rotary cutting knife 10 and the lower rotary cutting knife 12 are directed with their product side towards the scale flow 17 and only partially cut the product flow.

In this embodiment, an incision in the scale can be made one after the other from above and from below, the incision being able to be made somewhat deeper than the scale thickness. This means that there is no tear at the scale jump. In order to ensure that the cutting planes meet in the product, the two rotary cutting knives 10 and 12 can also be slightly inclined.

FIG. 4b shows a cross-sectional view of the lower rotary cutting knife 12 from FIG. 4a and the counter-pressure roller 13, which is only indicated schematically. Known knives can also be used in this embodiment, the cutting performance being doubled. For a particularly good cutting result, it can be advantageous to open the press belts symmetrically in the area of the cutting device and to provide a device which prevents the individual products from being mutually displaced. It is important that the cutting planes of the rotary cutting knives 10 and 12 are exactly aligned.

Fig. 5a shows a further embodiment of the invention, which corresponds essentially to that of Fig. 4, but with the rotary cutting blades 10 and 12 as close as possible are arranged one above the other, whereby the counter pressure rollers 9 and 13 can be omitted. As Fig. 5b shows, the two rotary cutting knives 10 and 12 are arranged as close as possible one above the other so that each cutting knife takes over the function of a counter pressure roller. In this embodiment, it is advantageous that no separate bottom knife or counter pressure roller is required.

In this embodiment, it can be advantageous if the positive scale always runs centrally through the two rotary cutting knives, since no supporting lower knife is provided. It is also advantageous if the distance between the upper and lower rotary cutting knives can be adjusted in order to take scales of different thicknesses into account. For this purpose, the lower roller bar provided for pressing the scale can be adjusted to the thickness of the scale, which represents a technically simple solution. However, devices can also be provided which open the press belt rolls symmetrically to the center of the scale. This means that no adjustment of the scale thickness is required and the scale runs exactly in the middle of the upper and lower cutting blades. The press belt roller strips can also be designed so that they open symmetrically upwards and downwards.

Fig. 6 shows a further embodiment of the invention, in which the individual blades or knives 11, 11 'of the upper knife 10 and the lower rotary cutting knife 12 mesh with one another when cutting through the scale flow with a positive scale. In this embodiment, the cutting knives 10 and 12 lie exactly one above the other. Due to a reduced blade density, ie a smaller number of individual blades on the circumference of the rotary cutting knife and only a slight overlap, the blades of the upper rotary cutting knife 10 and the lower rotary cutting knife can Comb 12. In this embodiment, there is a simultaneous cut from above and from below, so that no problems arise with respect to the aligned alignment of the cutting planes with one another. The cutting pattern is more even due to the alternating blade intervention from above and below.

Fig. 6b shows a cross-sectional view of Fig. 6a, wherein it can be seen that the scale flow 17 is pressed together by upper and lower press belts. At the same time it can be seen that the blades 11 and 11 'of the two rotary cutting knives cut the scale stream 17 symmetrically from above and from below.

FIG. 6c shows an enlargement of the cutting area drawn in a circle in FIG. 6. As can be seen, the upper rotary cutting knife 10 rotates counterclockwise and the lower rotary cutting knife 12 rotates clockwise, i.e. the upper rotary cutting knife 10 rotates in the cutting area in the conveying direction of the scale flow and the lower rotary cutting knife 12 also rotates in the cutting area in the conveying direction of the scale flow. Due to the alternating engagement of the upper and lower blades 11 and 11 ', the cutting forces occurring on the scale flow are evened out, so that fewer tears occur.

FIG. 7 shows a further embodiment of the invention for improving the cutting problems at the scale jump. In this embodiment, the individual knife blades 11 and 11 'of the rotary cutting knife are optimized. As shown in FIGS. 7a to 7c, some or all of the individual blades 11 of the upper knife 10 or also of the lower rotary cutting knife 12 are milled in V-shaped grooves, seen in cross section, which run parallel and in the longitudinal direction of the blades extend. These grooves extend to the front cutting edge of the knives and thereby form a zigzag structure on the outer surface of the knife blade, ie each individual blade has micro-serration. In this embodiment, the concentration of the cutting force at a certain point cuts the product before an excessive force can build up. The provision of micro-toothing can be provided not only for upper rotary cutting knives but also for lower rotary cutting knives. This micro toothing can also be used advantageously in one-piece cutting knives with or without a sawtooth cutting edge.

Another embodiment of the invention is shown in FIG. 8. In this embodiment, only an upper rotary cutting knife 10 with individual blades 11 is provided, which interacts with a conventional, cylindrical lower counter knife 12. In contrast to the conventional mode of operation, however, the upper rotary cutting knife 10 is now rotated in the cutting area against the conveying direction of the scale flow 17, which has a negative scale. It has surprisingly been found that by such a procedure, ie by rotating the rotary cutting knife against the conveying direction, the individual products in a negative scale are not torn open during the cut or pressed upwards. Rather, there is no cut mark, fraying or tearing in the area of the scale jump. In order to ensure that the individual blades 11 of the rotary cutting knife do not cut with a blade corner 20 but with the blade cutting edge 22, a rotary cutting knife 10 is used in the embodiment shown in FIG. 8, which is normally used on the left side of the scale stream 17. By using the "left" knife on the right and turning the knife counter to the direction of flow of the shingled stream surprisingly results in extremely good cutting behavior at the shingled jump.

Fig. 9 again illustrates the conditions occurring in the cutting area, but using the example of the positive scale. As FIG. 9a shows, the cutting edge 22 of each cutting blade 11 cuts through the products 16 and 18 lying on top of one another, so to speak, pulling from the bottom upwards by the method according to the invention. FIG. 9b illustrates the cutting forces that occur. As can be clearly seen, the resulting cutting force F _{R is} no longer directed essentially vertically downward, but instead forms a substantially larger angle with the shear edge 21 and the adjoining, vertical shear surface 21 'of the lower product 16 than with conventional cutting 1 and 2 is the case.

FIG. 10 again illustrates the different relationships in conventional cutting (FIG. 10a) and in cutting according to the invention (FIG. 10b). Here, the cutting force on the bottom sheet of the product 18 above is indicated with an arrow. As can be clearly seen, in the method according to the invention this sheet is no longer pressed vertically from above onto the shear edge 21 or the shear surface 21 '. Rather, the resulting force points away from the shear surface 21 'or the shear edge 21.

By reversing the direction of rotation of the rotary cutting knife, the tendency to tear is significantly reduced in the area of the scale jump, so that neither tears nor fraying occur. As shown in FIG. 8, when reversing the direction of rotation and when using a rotary cutting knife with a toothed Cutting edge contour should be ensured that, viewed in the direction of rotation, the front corner of the subsequent cutting tooth or the subsequent cutting blade 11 is offset radially inwards relative to the cutting edge of the preceding cutting tooth or the preceding cutting blade. If this were not the case, the cutting teeth would “chop” into the product with their corners and would not make a pulling cut with their cutting edge 22.

A further advantageous embodiment of the invention can consist in arranging the upper rotary knife 12 as the lower rotary knife in a positive scale shown in FIG. 2 or 8. Accordingly, the lower counter pressure meter 12 would then have to be arranged as an “upper knife” over the scale. In the case of a direction of rotation of the rotary cutting knife in the conveying direction, this arrangement or procedure can be used to prevent the product 18 lying on top at the shear edge 21 of the product 16 lying underneath from being partially sheared and thereby tearing. This arrangement thus corresponds to that of FIG. 6, although a conventional counter-pressure meter is used as the upper knife.

14 shows a very particularly advantageous embodiment of a rotary cutting knife with individual blades, which is suitable for both directions of rotation. In the case of this rotary cutting knife 10, a large number of individual cutting knives or cutting blades are also fastened on a knife carrier, but here, in contrast to the conventional arrangement according to FIG. 1, the individual cutting blades are radially aligned. At the same time, the individual cutting blades 11 are triangular in cross section, ie a ridge line 50 runs on the line of symmetry of the knife blade and this ridge line 50 is symmetrically followed by two inclined surface sections 52 and 54 (see Fig. 14b). The radially inner part of each knife blade is in turn of conventional design, ie is provided with an opening through which two fastening screws are guided. According to the invention, however, each ridge line 50 of each knife blade 11 runs radially, that is to say there is an overall symmetrical structure which has 36 individual blades in the embodiment shown.

The rotary cutting knife designed in this way has a symmetrically designed cutting contour, which enables the knife to be used clockwise and also counterclockwise. As has already been stated, with conventional rotary cutting knives with an asymmetrical cutting line contour, care must be taken that, viewed in the direction of rotation, the front corner of the subsequent cutting tooth or the subsequent cutting blade is offset radially inwards relative to the cutting edge of the preceding cutting tooth or the preceding cutting blade. With the rotary cutting knife shown in FIG. 14, however, no protruding cutting corners occur at all, so that this knife can be used on a cover.

As shown in FIGS. 14b and 14c, when the rotary cutting knife rotates counter to the conveying direction, the cutting edge 56 is gently cut in. The same applies to rotating the rotary cutting knife 10 in the conveying direction (FIG. 14c), since in this case too, the cutting edge 58 cuts properly into product 14.

This rotary cutting knife according to the invention has considerable advantages since a cut in or against the product flow direction is possible. On the one hand, this means there is no confusion between left- and right-turning Knives more possible. The service life can also be significantly improved since a knife that is blunt in the direction of rotation can continue to be operated in the other direction of rotation. Finally, in contrast to the known asymmetrical rotary cutting knife, this symmetrical knife can be manufactured more easily, but the basic advantages such as the easy interchangeability of the knife blades are retained. In principle, it is also conceivable to design a rotary cutting knife as shown in FIG. 14 as a one-piece knife.

Although mainly rotary cutting knives with individual blades or individual knives arranged thereon have been described above, all of the embodiments of the invention can also be used with rotary cutting knives formed in one piece. With the exception of the fourth embodiment, it is also not necessary for the rotary cutting knife to have a sawtooth-shaped or serrated cutting edge contour. In particular, the method described in connection with FIG. 8 can also be used advantageously in rotary cutting knives which have a circular cutting edge contour. Rotary cutting knives which have a flat ground peripheral area, i.e. have an area extending over the entire circumference. By combining such rotary cutting knives with the method according to the invention, particularly good results can be achieved due to the reduced frictional forces.

In the case of products with a fold, it is also advantageous if the so-called longitudinal cut is carried out first, ie the cut parallel to the fold. As a result, the shingled stream on the subsequent head and foot incision can be cut without tearing on the shingled stream if the products 16 below are arranged so that the fold of the product 16 below is located in the region of the cavity 20. If an additional lower knife with a knife bar is used which has a side wall sloped at 30 °, even better results can be achieved.

11 shows a side view of a rotary cutting station according to the invention, the actual rotary cutting knives not being shown. The rotary cutting station 30 shown is located in front of a corner deflection 40, which deflects the stream of shingles by 90 °. According to the invention, the press belts 32 of the rotary cutting station 30 are now extended in the direction of the corner deflection 40 and act as a supporting strip for the corner deflection 40. As shown in FIG means to be deflected in front of the housing edge 33. As a result, a further conveyor belt is required in such conventional machines in order to convey the stream of shingles to the corner deflection 40. According to the invention, however, the press belts 32 are significantly extended beyond the housing edge 33 of the rotary cutting machine 30 and thus act as a supporting strip for the corner deflection 40, as a result of which a separate supporting strip including drive can be omitted. The reference numerals 34 and 36 denote deflection rollers.

12 and 13 show a further embodiment of a rotary cutting station according to the invention, in which the press belts 32 ', like in conventional stations, are deflected within the housing 30' and within the front housing edge 33 '. According to the invention, however, two further, short conveyor belts 42 are provided, which of the Press belts 32 'are driven. For this purpose, the two short conveyor belts 42 are each guided on a deflection roller 44, which also deflects the press belts 32 '. At the front end of the short conveyor belts 42, these are each guided around a further deflection roller 46, which has a smaller diameter than the deflection rollers 44. Such a small diameter at the front end of the conveyor belt proves to be advantageous for the transfer of the shingled stream to the corner deflection 40. A further conveying device 48 in the form of a roller bar is arranged in the center of the conveying stream, which is known per se, but in the present case also via the rotary cutting machine is extended to the corner deflection.

This second embodiment of a rotary cutting machine is particularly advantageous in that no separate conveyor belt with separate drives and a separate holder is required for the transport of the shingled stream from the rotary cutting machine to the corner deflection. Rather, the shingled stream can be conveyed with the aid of the short conveyor belt 42 to the corner deflection 40, the short conveyor belts 42 being driven via the press belts 32 ', which can save considerable costs. These two described embodiments of a rotary cutting station, which has an extension of the conveying devices which clearly extends beyond the rotary cutting station, can of course be used with all rotary cutting knives according to the invention or also with known rotary cutting knives.

It should again be expressly pointed out that all rotary cutting knives or methods for cutting a stream of flakes described in this application are considered to be part of the invention, even if not all of the embodiments are claimed separately are. The invention thus covers both the described arrangements of rotary cutting knives in a rotary cutting system and the rotary cutting knives themselves, that is to say devices, as well as the described methods. All dimensions and details described in the drawings are also to be regarded as belonging to the invention. The invention can be used particularly advantageously when cutting a shingled stream which consists of paper products stacked on top of one another in shingled fashion, with or without a fold.

The cutting methods according to the invention are particularly suitable for product feed streams, the scale of which is formed from products that have a minimum number of pages of 32 pages. The best results were achieved with products with 96 pages.

When using the cutting method according to the invention, it may be necessary to press the product flow against the counter knife from above or below. Here, it has proven to be advantageous not to arrange the counter pressure meter at the level of the conveying level, but somewhat above the conveying level. This results in some compensation when using product streams with a relatively high thickness.

It can also be advantageous to support the product flow by means of a resiliently movable central support, for example a roller conveyor, which can be mounted so as to be pivotable about a horizontal axis. This swiveling roller conveyor can be moved via a drive rod so that it always supports the product flow. An additional pressure roller is particularly advantageous, which presses the product flow before the inlet between the two press belts within the cutting station.

Claims (11)

Method for cutting paper products (16, 18) conveyed in a positive scale flow (17) with a rotary cutting knife (10),
characterized in that
the rotary cutting knife is arranged below the stream of shingles, cuts through it from bottom to top and is rotated against the direction of conveyance of the stream of shingles. Method for cutting paper products (16, 18) conveyed in a positive scale flow (17) with a rotary cutting knife (10) which is rotated in the conveying direction of the scale flow,
characterized in that
the rotary cutting knife is arranged below the stream of shingles and cuts through it from bottom to top. Method for cutting paper products (16, 18) conveyed in a flake stream (17) with a rotary cutting knife (10) which is arranged above the flake stream and cuts it from top to bottom
characterized in that
the rotary cutting knife is rotated against the conveying direction of the scale flow. Method according to at least one of the preceding claims,
characterized in that
On the side of the scale flow opposite the rotary cutting knife, a counter-pressure knife essentially configured as a circular cylinder is arranged. Method according to at least one of the preceding claims 1 to 3,
characterized in that
On the side of the scale flow opposite the rotary cutting knife, a counter-pressure knife designed as a rotary cutting knife is arranged. Method according to claim 5,
characterized in that
the two knives comb with one another, are arranged one behind the other, or lie essentially against one another with their cutting surfaces. Method according to at least one of the preceding claims 1 to 6,
characterized in that
As a rotary cutting knife, a knife is used which has a round base body, on the outer circumference of which a plurality of individual, essentially rectangular blades are fastened, the base body preferably being frustoconical, the blades being fastened on its conical outer surface, and an angle with their longitudinal axes enclose to the radius of the body. Method according to claim 7,
characterized in that
the blades are arranged on the base body in such a way that a leading corner edge of a blade has a smaller distance from the center of the base body than a trailing corner edge of the same blade. Method according to at least one of the preceding claims,
characterized in that
Blades are used whose cutting edge has micro-serration. Method according to at least one of the preceding claims,
characterized in that
Print products with a page number of more than 32 pages, in particular with 96 pages can be cut. Device for carrying out the method according to at least one of claims 1 to 10.

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