EP0960064B1

EP0960064B1 - Apparatus for transporting a web material

Info

Publication number: EP0960064B1
Application number: EP97912207A
Authority: EP
Inventors: John Joseph Dowling
Original assignee: Heidelberger Druckmaschinen AG
Current assignee: Heidelberger Druckmaschinen AG
Priority date: 1997-10-21
Filing date: 1997-10-21
Publication date: 2003-04-23
Anticipated expiration: 2017-10-21
Also published as: DE69721318T2; JP2001506958A; EP0960064A1; DE69721318D1

Description

The present invention generally relates to a method and apparatus for transporting material webs. More particularly, the invention relates to transporting a folded paper web in a web-fed rotary printing machine.

Devices, such as nip roller arrangements, are well known for pulling or drawing material webs through a web-fed rotary printing machine or a paper-production machine. In web-fed rotary printing machines, a nip roller arrangement is usually located in the former and folder section of the printing machine, usually underneath a former board which applies a longitudinal fold to the printed paper-web.

JP-A-01 192661 discloses a first shaft with a driven wheel which is mounted to the first shaft and a further non-driven wheel which is rotatingly mounted to the first shaft. Moreover, there is disclosed a secorid shaft with a driven wheel which is mounted to the second shaft and a further non-driven wheel which is rotatingly mounted to the second shaft. The wheels mounted to the first and second shaft have a diameter larger than the wheels mounted rotatingly the the first and second shaft. Each one of the wheels mounted to a shaft contacts a wheel mounted rotatingly to the other shaft and a material web is guided by the wheels and deformed in a wavelike manner.

NL 6506362 discloses a first and a second shaft with respective rotatingly mounted non-driven wheels and respective mounted driven wheels. A paper web is guided by the driven and non-driven wheels of the two shafts and deformed in a wavelike manner. Moreover, the two shafts are connected to eachother for common driving.

US 3,784,187 discloses a folding apparatus for a web-fed rotary printing machine which comprises groups of nip rollers arranged below first and second triangular former boards. The nip rollers pull the web downstream of the triangular former boards, so as to give tension to the web and to the folds of the web.

The nip rollers used in conventional nip roller arrangements of web-fed rotary printing machines often include a first driven roller which is made of rigid material, (e.g. steel or other metal) and a second, non-driven roller, which is covered with a resilient material (e.g. polyurethane). For transporting the web, the rigid roller is driven with a slightly higher speed than the web speed, and the tension applied to the web is controlled by the pressure between the driven and the non-driven nip roller. To increase tension in the web, the pressure between the two nip rollers is increased so that frictional force between the driven nip roller and the web is increased too.

As a result of the constant slip between the driven nip roller and the paper web, the nip rollers wear out very quickly. The wear of the nip rollers is increased when the driven nip roller is coated with a resilient material (for example rubber or polyurethane). Moreover, as a result of the slip between the nip rollers and the paper web, there is the danger of smearing the printed image. Further, there is the danger that changes in the web tension, in the form of small disturbances, are directly passed through the nip of the nip roller arrangement into the cutting sections or further folding sections of the printing machine.

It is an object of the present invention to provide a method and apparatus for directly controlling web tension. Exemplary embodiments relate to a nip roller arrangement, which is easy to produce and assemble, which prevents the propagation of disturbances in the web tension into subsequent sections of the printing machine, and which reduces wear of the nip rollers.

According to a first embodiment of the invention, a nip roller arrangement is provided for transporting a folded paper web in a web-fed rotary printing machine. This arrangement comprises a first nip roller having a first set of driven and non-driven wheels arranged side by side along a rotational axis of the first nip roller, and a second nip roller having a second set of driven and non-driven wheels arranged side by side along the rotational axis of the second nip roller, the wheels of the first and second nip rollers being arranged such that the driven wheels of said first roller face the non-driven wheels of the second roller to form a nip for receiving and conveying the web material.

According to another exemplary embodiment of the invention, the non-driven and/or the driven wheels of the first and second nip rollers are coated with a resilient material, such as any elastomer, including rubber or polyurethane.

According to still another exemplary embodiment of the invention, the driven wheels and/or non-driven wheels of the first and second nip rollers are formed of a rigid material, such as metal (e.g. steel).

Pursuant to a further embodiment of the invention, the diameter of the non-driven wheels of the first and second nip rollers is larger than the diameter of the driven wheels.

Further, each nip roller comprises a central drive shaft extending through the center of the driven and non-driven wheels, to which the driven wheels are drivingly connected by means of a clamp mechanism. The non-driven wheels of the nip rollers can be supported on the central drive shaft by bearings. Additionally, the driven and/or non driven wheels of the first and second nip rollers can be mounted axially immovable on the central drive shaft, in accordance with exemplary embodiments of the invention.

According to another exemplary embodiment of the invention, the central drive shafts of the nip rollers are drivingly connected to each other by meshing gears, such that the rollers have essentially the same rotational speed.

Furthermore, according to a further exemplary embodiment, at least one of the nip rollers can be movably supported by bearings such that a width of the nip for receiving and conveying the material web can be adjusted. Such a feature can be used to render the circumferential speed of the driven wheels of the first and second nip rollers essentially equal to the speed of the web material.

The present invention, together with additional objects and advantages thereof, will be best understood from the following description of exemplary embodiments when read in connection with the accompanying drawings, in which:

Fig. 1: is a schematic side view of a web-fed rotary printing machine with a nip roller arrangement according to an exemplary embodiment of the present invention;
Fig. 2: shows a schematic front view of a former board used in a web-fed rotary printing machine for longitudinally folding a printed web, with a nip roller arrangement according to an exemplary embodiment of the present invention located underneath the former board;
Fig. 3: shows a schematic three-dimensional side view of a nip roller arrangement according to an exemplary of the present invention, wherein the pressure between the nip rollers is adjustable by means of air-cylinders;
Fig. 4: shows a schematic side view of a driven wheel used in an exemplary nip roller arrangement of the present invention;
Fig. 5: shows a schematic side view of a non-driven wheel of a nip roller arrangement according to an exemplary embodiment of the present invention; and
Fig. 6: shows a schematic cross-sectional view of a nip roller arrangement according to an exemplary embodiment of the present invention.

As shown in Fig. 1, an exemplary nip roller arrangement 1 for pulling a printed web 4 in an exemplary web-fed rotary printing machine 2 is located downstream of a dryer section 6, a chill section 8 and/or a former board 10. The former board 10 is provided for longitudinally folding the printed web 4 before it is supplied to a downstream cutting section 12 for further processing.

Although the present invention is described herein with respect to a web-fed rotary printing machine, it is also usable in other kinds of apparatuses for processing web material. For example, as those skilled in the art will appreciate, the present invention is equally applicable to paper processing machines, such as paper production machines and so forth.

As shown in Fig. 2, the nip roller arrangement 1 includes at least a first nip roller 14 and a second nip roller 16, which are arranged on opposite sides of the web 4 (e.g., a printed and folded web), thereby forming a nip 18 for transporting the web 4.

As shown in Fig. 3, each of the

nip rollers

14 and 16 comprise a first set of driven wheels 20 and a second set of non-driven, free-wheeling wheels 22, the driven wheels and the non-driven wheels being arranged side by side along the

rotational axes

24 and 26 of the first and

second nip rollers

14, 16, respectively. Thereby, a driven wheel 20 of one nip roller is facing a non-driven wheel 22 of the other nip roller. That is, for each driven wheel 20 on one roller, there is a corresponding non-driven wheel 22 on the other nip roller, and vice versa.

As shown in the exemplary Fig. 3 embodiment, the

central drive shafts

34 and 36 of the first and

second nip rollers

14, 16 are drivingly connected to each other by means of

meshing gears

54 and 56, mounted to the

central drive shafts

34 and 36. Only one of the

drive shafts

34, 36 is driven by a motor 48, and the speed of the motor 48 is controlled in dependence on the press speed such that the circumferential speed of the driven wheels 20 of each of the

nip rollers

14, 16 equals the surface speed of the material web 4. To control the speed of the

nip rollers

14, 16, any known and readily available harmonic drive 50 can, if desired, be provided between the motor 48 and the respective central drive shaft which is driven by the motor 48. As an alternative embodiment either or both of the drive shafts can be driven.

As shown in Fig. 3, there can further be provided means for moving the two

nip rollers

14 and 16 with respect to each other, to adjust the width of the nip 18 between the two

nip rollers

14, 16 for transporting and conveying the web material 4. The movement or adjustment of the nip 18 can be performed by a moving means which includes, for example, levers 58a and 58b and

respective air cylinders

60a, 60b. Of course, any other kind of actuating device, such as electric motors or manual levers can alternately be used.

Referring to the exemplary Fig. 4 embodiment of the invention, the driven wheels 20 are formed of a body or core 44 of rigid material, such as metal (e.g. steel or any kind of metal). Further, as illustrated in Fig. 6, the exemplary driven wheels have a slightly smaller diameter than the non-driven wheels 22. As shown in Fig. 5, the non-driven wheels 22 include a rigid core 30 covered with a resilient material (e.g., a bonded material) or coating 28, such as rubber or polyurethane. As shown in the exemplary Fig. 6 embodiment, the coating 28 can be applied to the rigid core or body 30 of the non-driven wheels 22, and although the overall diameter of the non-driven wheels can be the same as or larger than that of the driven wheels in the Fig. 6 embodiment, the core 30 of each non-driven wheel is of a smaller diameter than the diameter of the body 44 of each driven wheel 20. In an alternative embodiment, the non-driven wheels 22 can be entirely formed of a resilient material.

In another embodiment of the invention, both the driven wheels 20 and the non-driven wheels 22 can be formed of a rigid material. Alternatively, as indicated by dashed lines in Fig. 4, a resilient coating 28A can be provided on the body 44 of the driven wheels 20 of the first and second nip

rollers

14, 16. In such an embodiment, the non driven wheels 22 can be formed as shown in Fig. 5, or can be formed of a rigid material, such as metal.

In an exemplary embodiment of the invention as illustrated in Figs. 3-6, each of the nip

rollers

14, 16 comprise a

central drive shaft

34, 36, respectively extending through the center of the driven and

non-driven wheels

20, 22, and being rotatably supported by bearings. As shown in Fig. 4, means are provided for drivingly connecting the driven wheels 20 of each nip

roller

14, 16 to a respective one of the

drive shafts

34, 36 by, for example, a key 38 and a groove 40 in the drive shaft. The non-driven, free wheeling wheels 22 are, for example, supported on the

central drive shafts

34 and 36 by bearings 42, as indicated in Figs. 5 and 6. To prevent axial movement of the non-driven wheels 22 on the

shafts

34, 36, the fitting of the bearings 42 on the shafts can be established with a reasonably tight tolerance, and sleeves can be provided between the driven and the

non-driven wheels

20 and 22 for maintaining a defined axial position of the wheels along the length of the

shafts

34, 36.

In an exemplary embodiment of the invention, the core or body 44 of the driven wheels 20 and the core or body 30 of the non-driven wheels 22 can be formed in two parts, which can be clamped together by any clamping means, such as screws 46 of Figs. 4 and 5. This exemplary configuration of the

bodies

44 and 30 of the driven and

non-driven wheels

20 and 22 provides easy assembling of the nip

rollers

14, 16 and provides for quick replacement of the wheels in the event one or more of the wheels becomes defective.

In an exemplary embodiment of the invention, the pressure between the first and the second nip

rollers

14 and 16 is adjusted such that there is no slip between the nip rollers and the surface of the web material 4. As a result of the resilient coating on the driven end/or non-driven wheels 22, the web material 4 comprises a corrugated shape such as shown in Fig. 6, by which the web 4 is stabilized and the web handling in subsequent processing units is improved. The corrugating effect, which is applied to the web 4, depends on the radial thickness of the resilient coating 28 and on the space between a driven wheel 20 and a non-driven wheel 22.

LIST OF REFERENCE NUMERALS

1: nip roller arrangement
2: web-fed rotary printing machine
4: printed web
6: dryer section
8: chill section
10: former board
12: cutting section
14: first nip roller
16: second nip roller
18: nip
20: driven wheel of the nip roller 14
22: non-driven, free-wheeling wheel of the nip roller 16
24: rotational axis
26: rotational axis
28: resilient material on the core 30 of the wheel 22
28A: resilient material of the core 44 of the driven wheel 20
30: core of the non-driven wheel 22
34: drive shaft of the first nip roller 14
36: drive shaft of the second nip roller 16
38: key
40: groove
42: bearings
44: core of the driven wheel 20
46: screws
48: motor
50: harmonic drive
54: gear
56: gear
58a: lever
58b: lever
60a: air cylinder
60b: air cylinder

Claims

Apparatus for transporting a material web with
a fast nip roller (14) having a first set of driven and non-driven wheels (20, 22) arranged side by side along a rotational axis (24) of the first nip roller (14);
and a second nip roller (16) having a second set of driven and non-driven wheels (20, 22) arranged side by side along a rotational axis (26) of the second nip roller (16), the wheels (20, 22) of the first and second nip rollers (14, 16) being arranged such that the driven wheels (20) of said first nip roller (14) face the non-driven wheels (22) of the second nip roller (16) to form a nip (18) for receiving and conveying the material web (4),
characterized in that the diameter of the non-driven wheels (22) of the nip rollers (14, 16) is larger than the diameter of the driven wheels (20), and that the nondrive wheels (22) of the nip rollers (14, 16) are coated with a resilient material, or are entirely formed of a resilient material.
Apparatus according to Claim 1,
wherein the non-driven wheels (22) of the nip rollers (14, 16) are formed in part of a rigid material.
Apparatus according to anyone of the Claims 1 or 2,
wherein the driven wheels (20) of the nip rollers (14, 16) are coated with a resilient material.
Apparatus according to Claim 3,
wherein the driven wheels (20) of the nip rollers (14, 16) are formed of a rigid material.
Apparatus according to anyone of the Claims 1 to 4,
wherein the resilient material is an elastomer.
Apparatus according to anyone of the Claims 2 to 5,
wherein the rigid material is metal.
Apparatus according to any one of the preceding claims,
wherein each nip roller (14, 16) further comprises a central drive shaft (34, 36) extending through the center of the driven and non-driven wheels (20, 22) and means for clamping the driven wheels (20) to said central drive shaft (34, 36).
Apparatus according to Claim 7,
wherein the non-driven wheels (22) of the nip rollers (14, 16) are supported on the central drive shaft (34, 36) of each nip roller (14, 16) by bearings.
Apparatus according to Claim 7 or 8,
wherein at least one of the driven and non-driven wheels of the nip rollers (14, 16) are mounted axially immovable on the respective central drive shaft (34, 36).
Apparatus according to any one of the Claim 7 to 9,
wherein the central drive shafts (34, 36) of the nip rollers (14, 16) are drivingly connected to each other by meshing gears (54, 56), such that the driven wheels (20) of the nip rollers (14, 16) are driven at essentially the same rotational speed.
Apparatus according to any one of the preceding claims,
wherein at least one of the nip rollers (14, 16) is movably supported with respect to the other of the nip rollers (14, 16), such that a width of the nip (18) for receiving and conveying the material web (4) is adjustable.
Apparatus according to any one of the preceding claims,
wherein the driven wheels (20) of at least one of the nip rollers (14, 16) are configured to be driven with a circumferential speed essentially equal to a speed with which the material web (4) is conveyed through the nip (8).