EP3901075A1 - Folding roller with coating, and coresponding foding apparatus - Google Patents

Abstract

The invention relates to a folding roller (1) for folding signatures in a folding device (10), the folding roller (1) comprising a cylindrical folding roller body (3) with a lateral surface, the lateral surface having at least partially an elastic coating (5) The invention is therefore based on the object of creating a solution with which folded products of different and / or different thicknesses can be produced without changing the roller gap (15) between the pair of folding rollers (14) with the same folding quality and thus also an adjustment of the roller gap ( 15) is not required during continuous printing or ongoing production. This object is achieved in that the device according to the invention comprises a folding roller (1) in which the elastic coating (5) is compressible.

Description

The invention relates to a folding roller for folding signatures in a folding device, the folding roller comprising a cylindrical folding roller body with a jacket surface, the jacket surface having at least partially an elastic coating.

Furthermore, the invention relates to a folding device for forming a fold on a signature to be folded, wherein in the folding device a signature to be folded is pressed by means of a folding knife into an incoming nip of an oppositely rotating pair of folding rollers to form a fold.

In addition, the invention relates to a method for operating a folding device, wherein, in order to form a fold on a signature to be folded, this is pressed by means of a folding knife into an incoming nip of an oppositely rotating pair of folding rollers spaced apart from one another at an axial distance a, comprising two rollers each having a roller radius r, wherein at least one of the rollers of the pair of folding rollers is used as a folding roller according to the above Invention is designed.

For forming folds on printed or unprinted signatures in, for example, offset, gravure or inkjet printing machines, numerous folding devices such as knife or knife fold devices are known from the prior art. Such folding devices can either be integrated into a printing machine, or they are used to fold the signatures outside the printing machine.

Here, the folding principle is essentially comparable with many folding units that work with folding rollers arranged in pairs. In pocket folding units, the leading edge of the signature essentially runs against a stop until the signature builds up and the resulting bulge is captured by a roller gap and conveyed through the pair of folding rollers to form a fold transversely to the transport direction of the signature.

So-called knife or knife fold devices usually consist of a folding table with a recess on which the sheet to be folded comes to rest. To form the fold, the sheet is pressed by a folding knife through the recess of the folding table into the infeed gap of two counter-rotating folding rollers. The folding rollers grasp the sheet with their outer surfaces and convey it into a strip line, forming a fold which runs parallel to the axis of rotation of the folding rollers. This ribbon line usually consists of several conveyor belts arranged next to one another at a certain distance, which either loop around at least one folding roller or are designed independently of the folding rollers.

Folding rollers used in such folding devices are also known from the prior art. So reveals the DE 38 36 342 A1 a so-called clocked folding roller which, for example, does not have a continuous cylindrical outer surface. In the DE 103 04 534 A1 a folding roller is disclosed which has a friction layer on certain parts of the surface.

The folding rollers known from the prior art have a more or less grippy outer surface in order to capture the signature and transport it through the nip, although the outer surface of the folding rollers is mostly relatively hard.

However, such hard outer surfaces of folding rollers have the disadvantage that the roller gap must be adapted both to the thickness of the substrate of the signature and to the number of pages, the thickness of the signature to be folded, etc.

Such setting processes are mostly carried out manually, require appropriate experience of the operating staff and represent an additional source of error in addition to additional time expenditure. or the folded product is squeezed too much and damaged as a result. A roller gap that is set too wide between the folding rollers, on the other hand, can also lead to a stopper or to an improperly executed fold.

In addition, it should be noted that due to fluctuating substrate thicknesses during continuous printing or during production, it may be necessary to adjust the nip even during ongoing production, which increases the risk of stoppers and / or additional waste.

Furthermore, particularly in the case of relatively thick and / or signatures to be folded that already have at least one fold, the folding rollers known from the prior art do not necessarily have to be set parallel to one another; have a suitable angle to each other.

The invention is therefore based on the object of creating a solution with which both different and / or differently thick folded products can be produced without changing the roller gap between the pair of folding rollers with the same folding quality and thus also an adjustment of the roller gap during the production run or the ongoing Production is not required.

This object is achieved by a folding roller according to claim 1. The device according to the invention comprises a folding roller in which the elastic coating is compressible.

Furthermore, the device according to the invention comprises a folding device in which at least one roller of the counter-rotating pair of folding rollers is designed as a folding roller with an elastic and compressible coating.

In addition, the invention comprises a method for operating a folding device, the two rollers of the folding roller pair being set against one another in such a way that the center distance a is set equal to or smaller than the sum of the roller radii.

Such designs, based on a folding roller with an elastic and compressible coating, have the advantage that the elastic and simultaneously compressible coating adapts the effective roller gap to the respective printed product regardless of its substrate thickness and / or number of pages, so that the distance between the folding rollers to each other and thus the roller gap does not have to be changed or does not necessarily have to be changed both before a new production and during a production.

However, should a change in the roller gap be necessary due to the production of signatures to be folded of very different thicknesses, for example due to greatly varying page numbers and / or greatly varying substrate thicknesses, the roller gap can be set within a large tolerance range and is therefore much less critical because changes in the signature thickness can be compensated to a large extent by the elastic and compressible coating of at least one folding roller.

Furthermore, due to the compressibility of the coating, fluctuations in thickness within the signature, usually caused by already existing folds of the signature to be re-folded, can be compensated, thereby avoiding, for example, setting a suitable angle between the axes of rotation of the folding rollers.

The compressibility of the coating is essential here, since it excludes the formation of a bead at the nip compared to purely elastic and thus incompressible coatings. Such bulges make it difficult or prevent the signature from being captured by the nip and drawn securely into the nip. In addition, with a purely elastic and thus incompressible coating, the formation of a bead results in a non-uniform speed profile within the nip, which damages the signature to be folded or - in the case of multiple-layered signatures to be folded - the individual layers can be shifted relative to one another, which is unsatisfactory overall Product quality leads.

According to an advantageous embodiment of the invention, the coating consists of foamed polyurethane. Polyurethane has a very high fatigue strength and wear resistance and thus ensures a long service life of the coating.

In a further advantageous embodiment of the invention, the coating consists of microcellular polyurethane, since this has even higher strength and damping properties.

Fig. 1

einen grundsätzlichen Aufbau einer beschichteten Falzwalze

Fig. 2

eine Falzwalze umfassend eine Mehrzahl von schalenförmigen Segmenten

Fig. 3

eine Falzeinrichtung mit Falzmesser und Bandleitung unterhalb der Falzwalzen

Fig. 4

eine Falzeinrichtung mit Falzmesser und eine die Falzwalzen umschlingende Bandleitung

Preferred developments of the invention emerge from the subclaims and the following description. Various exemplary embodiments of the invention are explained in more detail with reference to the drawings, without being restricted thereto. It shows:

Fig. 1

a basic structure of a coated folding roller

Fig. 2

a folding roller comprising a plurality of cup-shaped segments

Fig. 3

a folding device with folding knife and ribbon cable below the folding rollers

Fig. 4

a folding device with folding knife and a tape line wrapping around the folding rollers

The present invention relates to a folding roller for folding signatures in a folding device, the folding roller comprising a cylindrical folding roller body with a jacket surface, the jacket surface having at least partially an elastic coating.

The basic structure of such a folding roller 1 is shown in Fig. 1 pictured. A folding roller 1 rotates about an axis of rotation 2 and essentially comprises a cylindrical folding roller body 3, which has a lateral surface through which the signature to be folded is detected and also forms the fold to be generated. Furthermore, the folding roller 1 generally comprises a roller journal 4 at both ends, on which the in Fig. 1 bearings, not shown, are attached. These bearings are usually located in folding roller levers, not shown, so that each folding roller 1 is rotatably mounted about its axis of rotation 2, so that the distance between the folding rollers 1 of the pair of folding rollers 14 can be changed. An elastic coating 5 is at least partially applied to the outer surface of the folding roller body 3, the elastic coating 5 being compressible.

The outer surface of the folding roller body 3 can, as for example in Fig. 1 shown, completely have a coating 5. However, it is also possible that in certain areas in the axial extent of the axis of rotation 2 no coating 5 is applied to the lateral surface, so that, for example, the in Fig. 4 The strip line 16 shown can run directly on the folding roller body 3 in these uncoated areas.

However, it is also possible that the coating 5 is applied only in certain areas in the circumferential direction on the outer surface of the folding roller body 3, for example only in the areas in the circumferential direction comparable to clocked folding rollers 1 with which the signature to be folded is captured and folded away from the outer surface will.

The elastic, compressible coating 5 of the outer surface of the folding roller body 3 consists in an advantageous embodiment of the invention of foamed polyurethane or of microcellular polyurethane. As an elastic polymer, polyurethane is suitable for such areas of application due to its high strength and resistance. By designing the coating 5 as a foamed or microcellular polyurethane, the compressibility of the coating 5 is ensured in order to avoid bulging in the roll gap 15.

Fig. 2 shows an alternative embodiment of a folding roller 1 according to the invention. In this embodiment, the folding roller body 3 is not a rigid and unchangeable component of the folding roller 1 as in FIG Fig. 1 shown, rather includes in the in Fig. 2 The folding roller 1 of the folding roller body 3 shown here has a plurality of cup-shaped segments 6 that can be joined to one another, with an elastic and compressible coating 5 being applied to at least part of the surface area formed by the cup-shaped segments 6.

The in Fig. 2 In the example shown, the folding roller body 3 consists of two half-shell-shaped segments 6, which extend over the entire length of the folding roller body 3 and are clamped to one another and to the shaft 7 of the folding roller 1 by means of connecting elements 8 designed as screws, for example. Although not in Fig. 2 shown, it is also possible to arrange a plurality of shell-shaped segments 6 next to one another in the axial extent of the folding roller body 3. It is also fundamentally possible to arrange more than two segments 6 in the circumferential direction of the folding roller body 3.

By designing the folding roller body 3 as a plurality of segments 6 that can be joined to one another, it is thus possible to replace the segments 6, which are at least partially coated with the coating 5, and thus the coating 5 when worn, without the folding roller 1 as a whole and thus the roller journals 4 must be dismantled from the storage, not shown.

The in FIGS. 1 and 2 The folding rollers 1 shown, the coating 5 has a thickness in the radial extension of 3 millimeters to about 30 millimeters. In a particularly preferred embodiment, the coating 5 has a thickness in the radial extension of approximately 10 millimeters to approximately 20 millimeters.

The coating 5 also consists of an elastic, compressible material with a Shore hardness of approximately 20 Shore D to approximately 80 Shore D, with the hardness of the coating 5 preferably in a range of approximately 40 Shore D in a particularly advantageous embodiment up to about 70 Shore D.

Fig. 3 shows a folding device 10, in which the folding roller 1 according to the invention is used by way of example, and with which a fold can be formed on a signature (not shown) to be folded.

The signature to be folded is usually transported on the folding table 13 in the direction perpendicular to the plane of the drawing into the folding device 10 and is braked at least by a sheet stop (not shown) and thus positioned in a defined position on the folding table 13.

The folding device 10 further comprises a pair of folding rollers 14 of counter-rotating rollers, at least one roller of the counter-rotating pair of folding rollers 14 being designed as a folding roller 1 according to the invention. In an advantageous embodiment, both rollers of the pair of folding rollers 14 are designed as folding rollers 1 according to the invention with an elastic and compressible coating 5. If only one roller of the pair of folding rollers 14 is designed as a folding roller 1 according to the invention, the other roller is designed with a hard folding roller body 3.

The two counter-rotating rollers of the pair of folding rollers 14 form a roller gap 15 into which the signature to be folded is drawn in due to the direction of rotation.

The folding device 10 furthermore comprises a folding knife 11 which, at least at the point in time at which the folding knife 11 presses the signature to be folded into the nip 15, executes a direction of movement 12 essentially perpendicular to the plane spanned by the folding table 13. The folding knife 11 can either be designed as a rocker, be arranged in a rotating folding drum, or be driven by other mechanisms such as a crank drive.

By pressing the signature to be folded into the nip 15, the signature is captured by the pair of folding rollers 14 and drawn through the nip 15 to form or form a fold.

The signature folded by the pair of folding rollers 14 is transported further through the direction of rotation of the pair of folding rollers 14 and fed into a ribbon line 16 so that the signature is guided out of the folding device 10 by means of the ribbon line 16 in the transport direction 17.

Fig. 3 shows a folding device 10 in which the ribbon line 16 serving to receive the folded signature is arranged below the counter-rotating pair of folding rollers 14.

Fig. 4 FIG. 10 shows a folding device 10 which is essentially identical to that in FIG Fig. 3 folder 10 shown is. The difference between the in Fig. 3 and the in Fig. 4 folding device 10 shown is that the in Fig. 4 The folding device 10 shown comprises a strip line 16, in which the strip line 16 partially wraps around both rollers of the pair of folding rollers 14, so that the signature to be folded is guided directly into the strip line 16 when it is detected through the roller gap 15.

At the points at which the strip line 16 wraps around the folding rollers 1, the compressible coating 5 can either have a groove, or no coating 5 is applied to the outer surface of the folding roller body 3 in these areas.

Although not shown in the figures, a combination of those shown in FIGS Figures 3 and 4 The variants shown are possible, so that a first roller of the pair of folding rollers 14 is at least partially wrapped by a strip line 16, while the other part of the strip line 16 is arranged below the second roller of the pair of folding rollers 14. It is irrelevant here whether the first roller and / or the second roller of the pair of folding rollers 14 is designed as a folding roller 1 according to the invention with an elastic, compressible coating 5.

Fig. 5 FIG. 14 shows a detailed view of a pair of folding rollers 14 from FIG Fig. 3 or 4 . The in Fig. 5 The pair of folding rollers 14 shown here can be designed either just one of the two rollers or both rollers of the pair of folding rollers 14 as a folding roller 1 according to the invention with an elastic and compressible coating 5. In a preferred embodiment, both rollers of the pair of folding rollers 14 are designed as folding rollers 1 according to the invention with an elastic and compressible coating 5.

How out FIGS. 3 and 4 As can be seen, the two rollers of the pair of folding rollers 14 rotate in opposition to one another during operation, but for the sake of clarity the arrows of the rotational movements are not shown in FIG Fig. 5 shown.

The first roller of the pair of folding rollers 14 has a first roller radius r1 in the normal state that is not under compressive stress. The second roller of the pair of folding rollers 14 also has a second roller radius r2 in the normal state that is not under compressive stress. The first roller diameter d1 of the first roller is twice the first roller radius r1, the second roller diameter d2 of the second roller is twice the second roller radius r2.

In the case of folding roller pairs 14 known from the prior art with a relatively hard outer surface of the folding roller body 3, with a setting suitable for production to avoid stoppers or product damage such as pinch folds etc., a gap remains between the first and second roller of the folding roller pair 14, so that at from the prior art known folding roller pairs 14 the distance between the two axes of rotation 2 is greater than the sum of the first roller radius r1 and the second roller radius r2.

Due to the inventive elastic and compressible coating 5 of at least one folding roller 1 of the pair of folding rollers 14, however, it is also possible to set the two rollers of the pair of folding rollers 14 in such a way that the center distance a, i.e. the distance between the two axes of rotation 2 of the two rollers of the pair of folding rollers 14, equal to or smaller than that Sum of the first roller radius r1 and the second roller radius r2 and thus equal to or smaller than the sum of the roller radii r1, r2.

In Fig. 5 a setting is shown in which the center distance a is smaller than the sum of the roller radii r1, r2, so that the surface lines overlap in the drawing. Of course, this overlap does not occur in reality; rather, the lateral surface of the at least one elastic and compressible coating 5 is flattened in the contact zone. Rather, this illustration is intended to make it clear that the center distance a can also be smaller than the sum of the roller radii r1, r2.

With such a setting, a roller gap 15 is thus created in which a signature to be folded is always drawn, which means a high level of operational reliability. Signatures to be folded of different thicknesses can be compensated for by the compressibility of the coating 5.

The center distance a of the pair of folding rollers 14 can be set in a particularly preferred embodiment in such a way that the center distance a is approximately 0.1 millimeters to approximately 5 millimeters smaller than the sum of the roller radii r1, r2. With this setting, a constant pressure between the rollers of the pair of folding rollers 14 is ensured without driving too high a pressure and thus being able to capture and fold signatures to be folded with a smaller or greater thickness.

Regardless of whether the center distance a is equal to or smaller than the sum of the roller radii r1, r2, the center distance a can be kept constant with a changing signature thickness due to the compressibility of the coating 5 of a folding roller 1 according to the invention. This applies, on the one hand, to setup processes that are no longer required when there is a change in production and, on the other hand, to changes in the folding roller setting that are no longer required during production.

List of reference symbols

1

Folding roller

2

Axis of rotation

3

Folding roller body

4th

Roll neck

5

Coating

6th

segment

7th

wave

8th

Connecting element

10

Folding device

11

Folding knife

12th

Direction of movement

13th

Folding table

14th

Pair of folding rollers

15th

Nip

16

Band management

17th

Transport direction

a

Center distance

d

Roll diameter

r

Roll radius

Claims (15)

Folding roller (1) for folding signatures in a folding device (10), the folding roller (1) comprising a cylindrical folding roller body (3) with a lateral surface, the lateral surface having at least partially an elastic coating (5), characterized in that the elastic coating (5) is compressible. Folding roller (1) according to Claim 1, characterized in that the coating (5) consists of foamed polyurethane. Folding roller (1) according to Claim 1, characterized in that the coating (5) consists of microcellular polyurethane. Folding roller (1) according to one of Claims 1 to 3, characterized in that the folding roller body (3) comprises a plurality of cup-shaped segments (6) which can be joined to one another. Folding roller (1) according to one of Claims 1 to 4, characterized in that the coating (5) has a thickness of 3 mm to 30 mm. Folding roller (1) according to Claim 5, characterized in that the coating (5) has a thickness of 10 mm to 20 mm. Folding roller (1) according to one of Claims 1 to 6, characterized in that the coating (5) has a hardness of 20 to 80 Shore D, in a particularly advantageous embodiment 40 to 70 Shore D. Folding device (10) for forming a fold on a signature to be folded, with the folding device (10) pressing a signature to be folded by means of a folding knife (11) into an incoming roller gap (15) of an oppositely rotating pair of folding rollers (14) to form a fold is, characterized in that at least one roller of the counter-rotating pair of folding rollers (14) is designed as a folding roller (1) according to one of claims 1 to 7. Folding device (10) according to Claim 8, characterized in that at least one ribbon line (16) serving to receive the folded signature is arranged below the counter-rotating pair of folding rollers (14). Folding device (10) according to Claim 8, characterized in that at least one ribbon line (16) serving to receive the folded signature wraps around at least one folding roller (1) of the pair of folding rollers (14). Folding device (10) according to one of Claims 8 to 10, characterized in that the center distance a between the two rollers of the pair of folding rollers (14) is equal to or smaller than the sum of the roller radii r1, r2. Folding device (10) according to Claim 11, characterized in that the center distance a is 0.1 to 5 mm smaller than the sum of the roller radii r1, r2. A method for operating a folding device (10), wherein, in order to form a fold on a signature to be folded, the signature is inserted by means of a folding knife (11) into an incoming roller gap (15) of an oppositely rotating pair of folding rollers (14) spaced from one another at an axis distance a, comprising two rollers each having a roller radius r is pressed, wherein at least one of the rollers of the pair of folding rollers (14) is designed as a folding roller (1) according to one of claims 1 to 6, characterized in that the two rollers of the pair of folding rollers (14) are positioned against each other in this way that the center distance a is set equal to or smaller than the sum of the roller radii r1, r2. Method according to claim 13, characterized in that the center distance a of the pair of folding rollers (14) is set in such a way that the center distance a is made 0.1 to 5 mm smaller than the sum of the roller radii r1, r2. Method according to one of Claims 13 to 14, characterized in that the center distance a is kept constant with a changing signature thickness.

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