DE102019211219A1 - Folding roller with a circumferential groove and a ring arranged in the circumferential groove - Google Patents

Abstract

A folding roller according to the invention with at least one circumferential groove (6) and a ring (5) arranged at least partially in the circumferential groove, comprising a material with a Shore A hardness in the range between 50 and 95 Shore, is characterized in that the ring (5) at least one, preferably axially outer, elastic section (10), preferably a shoulder (10), which with respect to the folding roller (1), the groove (6) and / or a bottom (11) of the groove in each case at least proportionally is either movable and / or positionable and / or deformable radially. The invention makes it possible in an advantageous manner to both transport and fold printing materials precisely and without interference.

Description

The invention relates to a folding roller according to claim 1 and further objects according to claims 9, 13, 15, 16, 20 and 21.

Technical field of the invention

The invention lies in the technical field of the graphic industry and there in particular in the field of folding printing materials, such as papers.

The industrial folding of sheet-shaped printing material is carried out using folding machines, which generally include a feeder for the sheets and at least one folding unit with a plurality of folding rollers. The folding units of the machine can each include pocket folding units and / or knife folding units.

The sheets are folded between two rotating folding rollers that are positioned against one another. The peripheral surfaces of the folding rollers can be formed from metal. The folding rollers can have grooves in which rings made of an elastomer are received.

State of the art

The DE7904616U1 discloses a folding roller equipped with a friction jacket with rings made of easily elastically deformable material. The rings can be corrugated on their outer surface. The DE2854957A1 and the DE3743642A1 reveal something similar.

Two known but disadvantageous prior art solutions are detailed in FIGS 1A and 1B and are described below with reference to these figures. The disadvantages of such known solutions are also described there.

task

It is therefore an object of the invention to create improvements over the prior art which in particular make it possible to both transport and simultaneously fold printing materials precisely and without interference.

Solution according to the invention

According to the invention, these objects are achieved by a folding roller having the features of claim 1 and by further subjects according to claims 9, 13, 15, 16, 20 and 21. Advantageous and therefore preferred developments of the invention emerge from the subclaims and from the description and the drawings.

The material used according to the invention with a Shore A hardness in the range between 50 and 95 Shore is preferably an elastic material, more preferably an elastomer and in particular a polyurethane (PU), further in particular a so-called hard PU, for example a polyester urethane -Rubber.

In this application, “hard” material, in particular hard PU, is understood to mean: a material with a Shore A hardness between 50 and 95 Shore, in particular between 60 and 80 Shore or in particular 75 +/- 5 Shore. The material is not or only insignificantly foamed and therefore essentially solid. The material can be e.g. Vulkollan®. Hard PU as a material for folding roller rings offers the advantage that it is resistant to the build-up of ink and has a longer service life than rubber, for example, and is more "grippy" than rubber, i.e. it offers better substrate transport properties.

The material used according to the invention with a Shore A hardness in the range below 50 Shore is preferably an elastic material, more preferably an elastomer and in particular a polyurethane (PU), further in particular a so-called soft PU, e.g. a polyester urethane Rubber.

In this application, “soft” (or “soft”) material, in particular soft PU, is understood to mean: A material with a Shore A hardness of less than 50 Shore. The material is preferably foamed and therefore essentially cellular or porous and therefore compressible. Soft PU is particularly advantageous when transporting smooth papers.

As an alternative to a polyurethane (hard PU or soft PU), polyethylene or polypropylene can be used as the material, preferably as a hard or soft material.

The Shore hardness or Shore A hardness is a material parameter for elastic materials, elastomers and / or plastics and can be based on the standards DIN EN ISO 868 , DIN ISO 7619-1 and ASTM D2240-00 to be determined.

A folding roller according to the invention with at least one circumferential groove and a ring arranged at least partially in the circumferential groove, comprising a material with a Shore A hardness in the range between 50 and 95 Shore, is characterized in that the ring comprises at least one elastic section, which is at least partially radially movable and / or positionable and / or deformable with respect to the folding roller, the groove and / or a bottom of the groove.

The term “at least partially radial” means, for example, that in addition to a radial component, an axial component of mobility / positionability / deformability can also be present. An axial component that is insignificant compared to the radial component, for example less than 10% or less than 5% or less than 1%, is preferred.

The folding roller according to the invention makes it possible in an advantageous manner to both transport and fold printing materials precisely and without disruption. The rings are preferably made of hard PU. As a result of the sections according to the invention (also called “shoulders” below), the relatively hard rings nevertheless advantageously behave, at least in sections, like soft PU rings. The roller is simple and inexpensive to manufacture and maintain. In this case, the folding roller advantageously only has rings made of hard PU and no rings made of soft PU.

A first alternative, further folding roller according to the invention with a surface, ie circumferential surface, which is formed by segments, the segments in the axial direction ( 50 ) are formed alternately by first segments with a low, first Shore hardness and second segments with a high, second Shore hardness, and the first segments comprising first rings comprising a material with a Shore A hardness in the range below 50 Shore is characterized in that the second segments are second rings comprising a material with a Shore A hardness in the range between 50 and 95 Shore.

The alternative, further folding roller according to the invention also makes it possible in an advantageous manner to both transport and fold printing materials precisely and without disruption. The roller is also simple and inexpensive to manufacture and maintain.

A second alternative, further folding roller according to the invention is a folding roller with rings for the transport and folding of sheets of printing material, the rings being made of an elastic material, preferably PU, e.g. hard PU or soft PU, and either the rings each have adjacent hard and soft sections, the latter preferably designed as shoulders, or adjacent rings form hard or soft sections.

A third alternative, further folding roller according to the invention is a folding roller with circumferential grooves and rings for the transport and folding of sheets of printing material, with either the grooves each having a varying depth in the axial direction and / or the rings each having a varying depth in the axial direction have changing thickness.

The term “thickness changing in the axial direction” means, for example, that the thickness of the ring (depending on the axial position or as a function thereof) is not constant or that the ring has significantly different thicknesses in at least two axial positions. For example, the thickness of the ring can have a step. The thickness is preferably measured in the radial direction or is a radial thickness.

The alternative, second and third further folding rollers according to the invention also make it possible in an advantageous manner to transport and simultaneously fold printing materials precisely and without disruption. In addition, the roller or the rings of the roller are low-wear.

All of the folding rollers according to the invention each offer an excellent combination of sheet guiding property and folding property due to their structure.

A ring according to the invention made of elastic material for a folding roller with a circumferential groove for receiving the ring is characterized in that the ring has a thickness that changes in the axial direction.

The ring according to the invention or its use advantageously enables printing materials to be transported and also to be folded at the same time precisely and without interference. In addition, such a ring is low-wear.

Developments of the invention

A preferred further development of the invention can be characterized in that the section is a decentralized section, i.e. is arranged decentrally or eccentrically with respect to the ring in the axial direction.

A preferred further development of the invention can be characterized in that the section is an outer section, i.e. is arranged on the outside of the ring in the axial direction, preferably on the side edge of the ring.

A preferred development of the invention can be characterized in that a respective circumferential chamber is formed between the sections and the bottom of the respective groove and that the chamber is filled with air or with a compressible material other than air. The chambers allow the radial mobility and / or positionability of the sections or shoulders in an advantageous and simple manner. The chambers or the corresponding cavities preferably provide a sufficient hollow position Shoulders and thereby in turn their mobility / positionability achieved.

A preferred development of the invention can be characterized in that the chamber has a height, measured in the radial direction, which is constant in the axial direction, or that the chamber has a rectangular cross section. By choosing the length and height of the rectangle, the spring rate of the section or shoulder can be set precisely.

A preferred development of the invention can be characterized in that the chamber has a height, measured in the radial direction, which is variable in the axial direction, or that the chamber has a wedge-shaped cross section. By choosing the wedge-shaped cross-section, e.g. by choosing an appropriate angle for the wedge, the spring rate of the section or shoulder can be set precisely.

A preferred development of the invention can be characterized in that the Shore A hardness is in the range between 60 and 80 Shore or 75 +/- 5 Shore and / or that the material is an elastic material or an elastomer or hard polyurethane , the material being solid or non-cellular or non-foamed. By choosing the material and the Shore A hardness, the spring rate of the section or shoulder can be set precisely.

A preferred development of the first alternative, further invention can be characterized in that the first segments are made of an elastomer or (or in particular) of a soft polyurethane and the second segments of an elastomer or (or in particular) of a hard polyurethane are made. This allows simple production using known materials.

A preferred development of the first alternative, further invention can be characterized in that second rings are arranged at least partially in a circumferential, respective groove of the folding roller. The groove prevents undesired axial movement of the second rings and thus also of the first rings in a simple manner.

A preferred development of the first alternative, further invention can be characterized in that the first segments and the second segments are received butt-to-butt on the folding roller and that the first segments protrude radially from the second segments. The overhang improves the transport of the printing materials to be folded. The protrusion can be a few hundredths of a mm, for example.

A preferred development of the second alternative, further invention can be distinguished by the fact that in both cases the hard and the soft sections differ from one another at least in terms of a relatively lower or higher elasticity.

A preferred development of the ring according to the invention can be characterized in that the ring has one shoulder or two shoulders, the thickness of the shoulder or shoulders being reduced in relation to the thickness of the ring or the thickness of the ring at its thickest point.

The features of the invention, the developments of the invention and the exemplary embodiments of the invention also represent advantageous developments of the invention in any combination with one another. Further developments of the invention can also have the individual features or combinations of features disclosed in the above section “Technical field of the invention”.

Embodiments of the invention

The folding rollers according to the invention and their preferred developments are described in more detail below with reference to the drawings using preferred exemplary embodiments. Features that correspond to one another are provided with the same reference symbols in the figures.

• 1A und 1B Falzwalzen nach dem Stand der Technik;
• 2 erfindungsgemäße Falzwalzen;
• 3 erfindungsgemäße Falzwalzen;
• 4 erfindungsgemäße Falzwalzen;
• 5 erfindungsgemäße Falzwalzen;
• 6 erfindungsgemäße Falzwalzen; und
• 7 erfindungsgemäße Falzwalzen.

The drawings show:

• 1A and 1B Prior art folding rollers;
• 2 folding rollers according to the invention;
• 3 folding rollers according to the invention;
• 4th folding rollers according to the invention;
• 5 folding rollers according to the invention;
• 6 folding rollers according to the invention; and
• 7th folding rollers according to the invention.

Figure description

1A shows a folding roller 1 according to the prior art, which with a further folding roller 2 cooperates. Both rollers are preferably in a folding machine 100 arranged and are used for the production of folded products 101 made of material to be processed 102 .

The folding roller 1 points in the axial direction (direction 50 in the figure) alternating hard segments 3 and soft segments 4th on. The hard segments can be made of metal, in particular steel, and can be part or sections of the folding roller. On their surface these Segments have a corrugation in the axial direction. The soft segments can be made from a soft PU and as rings 5 ' be formed, which are received on the roller. The rings can be in circumferential grooves 6 be arranged on the folding roller. The same applies to the folding roller 2 .

The folding roller 1 has a larger proportion of hard segments with regard to its surface 3 and a smaller proportion of soft segments 4th , for example in the ratio of about 3: 2 or about 4: 3. The hard segments of a roller overlap in the respective overlapping areas 7th with hard segments of the roller opposite it.

The hard segments 3 have the function during operation of a good fold break in the material to be processed 102 , for example in paper (hereinafter called the "Fold" function), while the soft segments 4th have the function of ensuring good transport of the material (hereinafter referred to as the “grip” function). The folding rollers according to the invention described below also have these two functions.

The disadvantage of this prior art solution is that in the respective overlapping areas 7th clearly visible and therefore annoying lines in the material to be processed that reduce the quality of the folded product 102 can arise. Another disadvantage is the wear and tear on the roll surface.

1B shows another folding roller 1 According to the state of the art. This folding roller also points in the axial direction 50 alternating hard segments 3 and soft segments 4th on. The segments can be configured according to the in 1A The solution shown must be manufactured and have corresponding functions “Fold” and “Grip” during operation. The hard segments can have corrugation in the axial direction on their surface.

The folding roller 1 has a higher proportion of soft segments with regard to its surface 4th and a smaller proportion of hard segments 3 , for example in a ratio of about 2: 5 or 3: 5 or 4: 5. The soft segments 4th of a roller overlap in respective overlap areas 7th with soft segments of the roller opposite it. The overlap can be, for example, about a few millimeters. There is therefore compared to the 1A no overlap of hard segments, but an overlap of soft segments.

The disadvantage of this solution is that the fold break is less precisely generated due to the soft segments and the “grip” function is significantly more pronounced than the “fold” function.

2 shows a preferred embodiment of a folding roller according to the invention 1 a folding machine 100 , which preferably with a further folding roller 2 interacts rotationally. The folding rollers are used to manufacture folded products 101 made of material to be processed 102 , e.g. paper. Both folding rollers 1 and 2 can have a similar structure. The structure of the folding roller is therefore exemplified below 1 described.

The folding roller 1 or its roller core can be made of metal, preferably steel, and has (based on an axis of rotation of the folding roller 1 ) in the axial direction 50 alternating hard segments 3 and soft segments 4th on. The hard segments 3 are in the axial direction 50 alternating with hard segments 3a and hard segments 3b educated. The hard segments 3a are preferably made of metal, in particular steel, and can be a fixed / non-detachable part or sections of the folding roller 1 his. Alternatively, the hard segments 3a made of hard PU and designed as detachable rings. The hard segments 3b are preferably made of hard PU and can be a detachable part or detachable sections of the folding roller or be accommodated on the folding roller.

The soft segments 4th (or shoulders or bending bars) are preferably not formed from soft PU, as would be expected according to the prior art, but rather according to the invention from hard PU. In order to achieve that a soft segment can be formed despite the use of the material hard PU, the following is provided according to the invention in this embodiment: In a circumferential groove 6 the folding roller 1 is a soft segment in sections 4th a ring 5 at least partially arranged. The ring has a Shore A hardness in the range between 60 and 90 Shore, preferably between 60 and 80 Shore and particularly preferably around 75 Shore. The material of the ring is preferably solid, non-cellular or non-foamed. The ring 5 can have a recess in its soft section (on the rear, ie facing the roller core).

The ring can protrude slightly, for example about a few hundredths of a millimeter, over the surface of the folding roller. The ring 5 has a (based on an axis of rotation of the folding roller 1 in the axial direction 50 ) central section 5a and two (in the axial direction 50 ) axially outer sections 5b on. The sections 5b are elastically deformable and with respect to the folding roller 1 and / or in particular with regard to the groove 6 in the folding roller and / or a floor 11 of the groove (in the radial direction 51 ) each radially movable or displaceable. The latter means that the sections 5b under pressure, for example by pressing between the two rollers 1 and 2 be moved or displaced radially into the groove, preferably in the order of magnitude of the protrusion of, for example, a few hundredths of a millimeter.

In the embodiment shown, the groove 6 two sections: one (in the axial direction 50 ) central section 6a and two (in the axial direction 50 ) axially outer sections 6b . In the sections 6a the groove has a depth 8a and in the section 6b a shallower depth 8b . The respective depths are measured against the surface of the folding roller 1 in the area of the hard segments 3a . The circumferential grooves of the folding roller 1 can be made, for example, as grooves in the metal roller. The floor 11 the groove 6 is preferably designed in steps: a central, low step 11a and two adjacent, axially outer, high steps 11b .

The ring 5 has in section 6a a thick one 9a which is essentially the depth of the groove 8a corresponds to or is slightly larger (given the protrusion). In the section 6b the ring has a thickness 9b which is less than the depth of the groove 8b is, for example, only 50%, 60%, 70%, 75%, 80% or 90%. This creates between each (axially outer) shoulder 10 of the ring 5 and the respective soil 1 1b between the level 11b of the bottom of the groove 6 or the section 6b a surrounding chamber 12 . The chamber is preferably filled with air. Alternatively, the chamber can be filled with a compressible material, for example a soft PU. The chamber preferably has a rectangular cross section.

The chamber 12 according to the invention enables mobility or displaceability of the respective shoulder 10 in the radial direction 51 in the chamber or into the chamber.

This is how the shoulders work 10 of the ring 5 in operation (i.e. when transporting and folding the material 102 ) - despite the fact that they are made of hard PU - they are made similar to soft PU and enable the "grip" function to be provided.

The ring 5 is preferred in the groove 6 glued in, especially on the floor 11a or the level 11a of the soil 11 glued to the groove. Excess glue can be stored in two surrounding side chambers 13 be caught.

The ring 5 can optionally have a central and circumferential recess (in the axial direction) 14th exhibit. This can be found in the 15th likewise for mobility or displaceability of the hard PU material of the ring 5 in the radial direction 51 worry and thus in section 15th also provide the "grip" function.

2 indicates that the respective segments of the two rollers 1 and 2 an axial offset 52 are arranged offset to one another: The central section 5a of the ring 5 the folding roller 1 lies in a tough segment 3a the folding roller 2 opposite and vice versa. Shoulders 10 The Rings 5 of both folding rollers 1 and 2 each face each other. Given the slight protrusion of the rings 5 over the (preferably metal) surface of the respective folding roller 1 or 2 become the shoulders 10 each a little in the chamber assigned to them 12 moved or relocated. This creates the "grip" function, ie the shoulders look like they are made of soft PU. In an advantageous manner, however, no soft PU is used, but (in this embodiment) only hard PU.

As an alternative to the embodiment shown, the bottom 11 the groove 6 also be stepless. The chambers 12 would then be deeper, provided the thickness 9b of the shoulders 10 of the ring 5 remains the same. The fat 9b can also be chosen larger so that the chambers do not become too deep. In the area of the shoulders 10 can the protrusion of the ring 5 in this embodiment, larger than 15/100 mm can also be selected or, conversely, the ring can be selected 5 be made thinner centrally, that is axially between the shoulders, for example by turning.

3 shows another preferred embodiment of the invention. The structure is comparable to that in 2 shown, however, have the chambers 12 here a substantially wedge-shaped cross-section and the bottom 11 the groove 6 is not step-shaped (with the two steps 11a and 11b ), but developed steplessly.

4th also shows another preferred embodiment of the invention. Again, the structure is comparable to that in 2 shown, however, here are the stages 11a and 11b executed differently: the depth 8b the axially outer floor 11b are deeper than the lows 8a of the central floor 11a . Or to put it another way: the groove 6 has a central, high level 11a and two adjacent, axially outer, low steps 11b on.

In all shown embodiments according to the 2 to 4th the respective spring rate of the rings shown there 5 or their axially outer sections / shoulders 10 can be set as follows: choice of hard PU material; Choice of axial length and radial thickness of the shoulders; and / or choice of the axial length and radial depth of the groove under the shoulder. The ring and especially its shoulders are considered a spring.

5 also shows a further preferred embodiment of the invention. The structure is again comparable to that in 2 shown, however, there are two types of segments in this embodiment 3 and 4th or of rings 5 and 5 ' for use: the rings 5 are hard or made of hard PU and the rings 5 ' are soft or made of soft PU.

The Rings 5 are T-shaped and sit in grooves 6 the roller 1 ; the grooves 6 themselves are stepless.

Between the rings 5 there is a respective distance or a respective gap in the axial direction 16 . The Rings 5 ' sit on the surface of the roller 1 and between the rings 5 or in the gaps 16 . The Rings 5 ' have a radial protrusion 19th about the rings 5 to improve the "grip" function. The Rings 5 are in the axial direction of the grooves 6 held; the Rings 5 ' are in the axial direction of the rings 5 held.

The roller 2 has grooves 17th on in which soft rings 5 ' or rings 5 ' made of soft PU; these lie with the rings 5 ' the roller 1 across from. The rings 5 the roller 1 are hard surface segments 18th , e.g. made of steel, the roller 2 across from.

The Rings 5 ' of the rollers 1 and 2 work together to provide the "grip"function; the Rings 5 and the segments 18th the function "Fold" in cooperation. The Rings 5 ' both rollers 1 and 2 can be designed identically. The Rings 5 ' the roller 2 As an alternative to the embodiment shown, they can be somewhat wider than the rings 5 ' the roller 1 be trained so that they are with the rings 5 the roller 1 overlap and the "grip" function is improved.

6 shows another preferred embodiment of the invention. Again, the structure is comparable to that in 2 shown, however, have the rings 5 only one shoulder at a time 10 formed axially outer portion 5b on. A ring 5 the roller 1 or their one shoulder 10 only overlaps with a ring 5 the roller 2 or its one shoulder 10 . The sides of the rings 5 without developed shoulders do not overlap or overlap only insignificantly.

7th shows another preferred embodiment of the invention. In contrast to the 2 to 6 are the two reels 1 and 2 in 7th shown spaced apart so that the rings 5 and in particular the curvature of which is clearly visible. In operation, however, the rollers and the rings are adjusted to one another 5 in the grooves 6 pressed in so that the curvatures are not or less pronounced. Again, the structure is comparable to that in 2 shown, but the axial sections for the “grip” function in this exemplary embodiment are not due to shoulders but rather to a curvature of the ring 5 evoked. The ring is designed, for example, such that its cross section corresponds to a curved or bent rectangle. The curvature is preferably chosen such that a central section protrudes (radially) from axially outer sections.

List of reference symbols

1

Folding roller

2

Folding roller

3

hard segments

3a

hard segments (made of steel)

3b

hard segments (made of hard PU)

4th

soft segments (made of soft PU)

5

Rings (hard)

5 '

Rings (soft)

5a

central sections of the rings

5b

axially outer sections of the rings

6th

Grooves

6a

central sections of the grooves

6b

axially outer sections of the grooves

7th

Overlap areas

8a

Depth of the grooves

8b

Depth of the grooves

9a

Thickness of the rings

9b

Thickness of the rings

10

Shoulders of the rings / axially outer sections of the rings

11

Bottom of the groove

11a

Bottom of the grooves (steps)

11b

Bottom of the grooves (steps)

12

Chambers

12a

Height of the chamber

13

Side chambers

14th

central recesses

15th

Sections

16

Gaps

17th

Grooves

18th

Surface segments (hard)

19th

radial protrusion

50

axial direction (of the folding roller and / or the ring)

51

radial direction

52

axial misalignment

100

Folding machine

101

Folded product

102

material to be processed

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 7904616 U1 [0005]
• DE 2854957 A1 [0005]
• DE 3743642 A1 [0005]

Non-patent literature cited

• DIN EN ISO 868 [0014]
• DIN ISO 7619-1 [0014]
• ASTM D2240-00 [0014]

Claims (22)

Folding roller with at least one circumferential groove (6) and a ring (5) arranged at least partially in the circumferential groove, comprising a material with a Shore A hardness in the range between 50 and 95 Shore, characterized in that the ring (5) at least comprises an elastic axial section (10) which is at least partially radially movable and / or positionable and / or deformable with respect to the folding roller (1, 2), the groove (6) and / or a bottom (11) of the groove. Folding roller after Claim 1 , characterized in that the section is a decentralized section, ie is arranged decentrally or eccentrically with respect to the ring (5) in the axial direction (50). Folding roller after Claim 1 or 2 , characterized in that the section is an outer section, ie is arranged on the outside of the ring (5) in the axial direction (50). Folding roller according to one of the preceding claims, characterized in that a respective circumferential chamber (12) is formed between the sections (10) and the bottom (11) of the respective groove (6) and that the chamber is filled with air or with one other than air , compressible material is filled. Folding roller after Claim 4 , characterized in that the chamber (12) has a height (12a) measured in the radial direction, which is constant in the axial direction or that the chamber has a rectangular cross section. Folding roller after Claim 4 , characterized in that the chamber (12) has a height (12a) measured in the radial direction, which is variable in the axial direction, or that the chamber has a wedge-shaped cross section. Folding roller according to one of the preceding claims, characterized in that the Shore A hardness is in the range between 60 and 80 Shore or 75 +/- 5 Shore and / or that the material is an elastic material or an elastomer or hard polyurethane , the material being solid or non-cellular or non-foamed. Folding roller according to one of the preceding claims, characterized in that the ring (5) on a segment (3a) of the folding roller (1, 2) made of steel or on a further ring (5) made of an elastomer with a Shore A hardness in Area between 90 and 100 borders. Folding roller with a surface which is formed by segments, the segments in the axial direction (50) alternating from first segments (4, 5 ') with a low, first Shore hardness and second segments (3, 3b, 5) with a high, second Shore hardness, and wherein the first segments are first rings (5 ') comprising a material with a Shore A hardness in the range below 50 Shore, characterized in that the second segments are second rings (5) comprising a material having a Shore A hardness in the range between 50 and 95 Shore. Folding roller after Claim 9 , characterized in that the first segments (4, 5 ') are made of an elastomer or a soft polyurethane and the second segments (3, 3b, 5) are made of an elastomer or a hard polyurethane. Folding roller after one of the Claims 9 or 10 , characterized in that second rings (5) are at least partially arranged in a circumferential, respective groove (6) of the folding roller (1). Folding roller after one of the Claims 9 to 11 , characterized in that the first segments (4, 5 ') and the second segments (3, 3b, 5) are received butt-to-butt on the folding roller (1) and that the first segments (4, 5') are opposite the second segments (3, 3b, 5) have a radial projection (19). Folding roller with rings for the transport and folding of sheets of printing material, the rings (5, 5 ') being made of elastic material and either the rings having hard and soft sections (3, 4) adjacent to one another or rings that are adjacent to one another form hard or soft sections (5, 5 '). Folding roller after Claim 13 , characterized in that in both cases the hard and the soft sections differ from one another at least by a relatively lower or higher elasticity. Folding roller with circumferential grooves and rings for the transport and folding of sheets made of printing material, either the grooves (6) each having a depth (8a, 8b) that changes in the axial direction (50) and / or the rings (5, 5 ') each have a varying thickness (9a, 9b) in the axial direction (50). Folding roller pair for the transport and folding of sheets of printing material, comprising at least one folding roller (1, 2) according to one of the preceding claims. Pair of folding rollers Claim 16 , characterized in that both folding rollers (1, 2) of the pair of folding rollers are designed according to one of the preceding claims. Pair of folding rollers Claim 16 or 17th , characterized in that the folding rollers (1, 2) of the pair of folding rollers are arranged offset to one another in the axial direction (50) with respect to their grooves (6) or rings (5, 5 '). Pair of folding rollers Claim 18 , characterized in that grooves (6) and / or rings (5, 5 ') of one of the two folding rollers (1, 2) with respect to identical grooves (6) and / or rings (5, 5') of the other of the two folding rollers ( 1, 2) have an axial offset (52). Folding machine with at least one folding roller (1, 2) according to one of the Claims 1 to 15th or with at least one pair of folding rollers (1, 2) according to one of the Claims 16 to 19th . Ring made of elastic material for a folding roller with a circumferential groove for receiving the ring, characterized in that the ring (5, 5 ') has a thickness (9a, 9b) which changes in the axial direction (50). Ring after Claim 21 , characterized in that the ring (5, 5 ') has one shoulder (10) or two shoulders (10), the thickness of the shoulder or shoulders reducing with respect to the thickness of the ring or the thickness of the ring at its thickest point is.

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