CN114269987A

CN114269987A - Press unit

Info

Publication number: CN114269987A
Application number: CN202080059322.7A
Authority: CN
Inventors: C.施密德
Original assignee: Voith Patent GmbH
Current assignee: Voith Patent GmbH
Priority date: 2019-07-23
Filing date: 2020-06-24
Publication date: 2022-04-01
Also published as: WO2021013454A1; EP4004280A1; DE102019119894A1

Abstract

A machine for producing or processing a material web (9), in particular a paper, cardboard or tissue web, with a press unit comprising a press roll (1) and a mating press roll (8), wherein the press roll (1) is supported on a pivotable support arm (12) and is movable by means of at least one adjustment unit (14) between an operating position, in which the press roll (1) bears on the mating press roll (8), and a deactivated position, in which the press roll (1) does not bear on the mating press roll (8), characterized in that the press unit is a double press unit and the press roll (1) supported on the pivotable support arm (12) is arranged as a second press roll (1) in the web travel direction of the material web (9).

Description

Press unit

The present invention relates to a machine for producing or processing a material web, in particular a paper, paperboard or tissue web, with a press unit comprising press rolls and cooperating press rolls according to the preamble of claim 1.

The towel machine has, for example, a press unit consisting of a press roll and a mating press roll designed as a dryer cylinder, wherein the press roll is normally pivotably supported on a supporting arm relative to the mating press roll, so that the press roll can be moved by means of at least one adjustment unit acting on the supporting arm between an operating position, in which the press roll bears against the mating press roll, and a deactivated position, in which the press roll does not bear against the mating press roll. The adjusting unit is usually designed as a hydraulic cylinder.

Such a towel machine is known from document EP 1925723 a1, which has a press unit comprising at least one press roll and a mating press roll, wherein the press roll is supported on a pivotable support arm and can be moved by means of at least one adjustment unit acting on the support arm between an operating position, in which the press roll presses against the mating press roll, and a deactivated position, in which the press roll does not press against the mating press roll. The known machine comprises an adjustment unit with a blocking device, by means of which the adjustment unit can be mechanically locked in the operating position.

If the press roll is to be pivoted from the run position into the deactivated position, the mechanical lock established by the locking device can be released again, in order to re-establish the lock at a later point in time when the press roll is pivoted again into the run position.

From DE 4216264C 2 a press device is known, in which the paper web is passed through two press nips, which are formed by two press rolls and a common counter roll, which can be passed successively by the paper web together with a felt. Alternatively, instead of using a single felt, two different felts or drying screens are used.

The object of the invention is to provide a machine of the type mentioned at the outset, in which the above-mentioned disadvantages are overcome, wherein on the one hand a precise operating position is maintained without permanent, steady force loading of the actuating unit, wherein at the same time the locking mechanism, which is consumed by the locking arm, can be dispensed with.

This object is achieved by the features of claim 1.

The machine for producing or processing a material web according to the invention has a press unit comprising at least one press roll and a mating press roll, wherein the press roll is supported on a pivotable support arm and can be moved by means of at least one adjustment unit acting on the support arm between an operating position, in which the press roll presses against the mating press roll, and a deactivated position, in which the press roll does not press against the mating press roll. The machine according to the invention is characterized in that the press unit is a double press unit and the press roll supported on a pivotable support arm is arranged as the second press roll in the web travel direction of the material web and can be pressed in order to generate a predefined press pressure in the press nip.

Advantageous embodiments of the invention are specified in the dependent claims.

One design of the invention provides that the operating position comprises a plurality of operating states in which each press roll and the cooperating press roll, respectively, are pressed against each other to a different extent, wherein the locking device is configured such that the adjustment unit can be mechanically set in each of the different operating states. It is provided here that the first press roll is also pivotably arranged.

Preferably, the second press roll is configured as a shoe press roll. The press roll comprises a press shoe whereby the press roll does not require an internal source of support in order to close the nip between the press shoe and the mating roll. According to the invention, the nip is closed by means of an external lever system, i.e. a pressing pressure is applied. The linear force of the press nip is also generated by an external lever system, so that the press roll resembles a conventional press roll or suction press roll.

However, it can be provided that the pressure shoe bears on one or more support elements. If a plurality of individually supported support members are provided, they may have different stiffness, in particular at two of the edge zones, to improve the compression against the cooperating press roll. The mating press roll is in this case preferably a yankee cylinder. The edge regions each have a width of less than 500mm, preferably less than 300 mm.

According to the present invention, the advantages are obtained that the pressing system and the moving system of the shoe press are unified into one system. No safety control or monitoring of the line force is required. In contrast, the shoe press roll controlled according to the present invention can be treated like a conventional press roll, wherein a press arm operated by an actuator acts on the shoe press roll from the outside; the maximum line load is ensured by the oil pressure in the actuator or hydraulic cylinder. Also, no hydraulic regional control of the press shoe is required, but rather only one lubricating mechanism for the press jacket (sleeve) surrounding the press shoe is sufficient. The shoe press roll has simple structure and no internal adjusting mechanism, so the cost is saved.

The distance between the shoe press roll and the mating roll can be set arbitrarily, while in the case of an internal support source, the stroke is limited to a distance of about 20 to 30mm by the press jacket. This smaller distance can lead to damage to the clothing when the mating roll is hot.

According to the invention, a smaller deformation of the press jacket and the press sleeve of the shoe press roll is achieved, whereas the press jacket of the shoe press roll is bulged or deformed by the stroke of the active internal pressing system according to the prior art.

A further advantage of the pivotable shoe press roll according to the invention is that the nip force does not change when the diameter of the mating roll, e.g. the yankee cylinder, changes. Only one force needs to be applied by the adjustment mechanism, whereas the position of the shoe press roll is variable and adapted to the position of the mating roll.

According to a particularly advantageous design provision is made that the dewatering process can be optimized by rotation of the press rolls in or counter to the machine running direction.

According to an advantageous design, the shoe press roll has a rotatably supported press shoe or a press shoe arranged in a flexible connection.

It is also advantageous if the shoe press roll has a press shoe divided into a plurality of individually supported or controllable zones or zones of different hardness, especially in the edge zone. This allows an accurate tracking or adaptation of the contour of the mating press roll, in particular the yankee cylinder, to be achieved.

In a further advantageous embodiment, the shoe press roll has at least one yoke over its length for supporting the press shoe.

It is preferred that the press shoe is supported inside the shoe press roll on at least one soft, elastically yielding support member, which itself rests on at least one yoke. The press pressure between the mating press roll and the press shoe can be controlled by means of the support bar. The press roll is supported on a soft, elastically yielding and flexible support, whereby the press shoe can be pressed against the contour of a mating roll, e.g. a yankee cylinder, with the same pressing force over the entire width in order to close the nip between the press shoe and the mating roll. Due to the yielding and soft structure of the support member, the compaction of the press shoe is continuously tracked and adapted.

This means that deformations in the counter roll, for example a yankee cylinder, which occur, for example, as a result of temperature influences during operation, are compensated for by the elasticity of the support. If the shell surface of the counter roll is convex or concave during operation, this change in shape is therefore compensated by a correspondingly deformed support element, so that the press shoe always bears against the counter roll with the same contact pressure in the press nip. The pressing pressure is preferably adjusted. In this case, the moisture and/or temperature of the material web can be selected, preferably as a control variable for determining the pressing pressure.

Instead of a single support, a plurality of preferably interconnected supports arranged side by side can be provided according to the invention. The plurality of individually supported supports may have different hardness, in particular at two of the edge zones, to improve the pressing of the press shoe against the cooperating press roll. The mating press roll is in this case preferably a yankee cylinder. The edge regions each have a width of less than 500mm, preferably less than 300 mm.

It is also advantageous if a dewatering element, in particular a suction box or a suction reversing roll, is arranged in front of the second press roll in the web travel direction of the material web.

A further advantageous design provides that the second press roll has a diameter of at least 750 mm.

It is advantageous for the press unit comprising cooperating press rolls to have a first press roll configured as a suction press roll arranged in front of a second press roll in the web travel direction of the material web.

It is particularly advantageous to provide drying cylinders, in particular yankee drying cylinders or levelling cylinders, as co-operating press rolls.

The invention is further elucidated by way of example with reference to the accompanying drawing. Wherein:

figure 1 shows a schematic view of a shoe press roll that can be used according to the invention,

figure 2 shows a shoe press roll which can be adjusted to a mating roll by means of a support arm,

fig. 3 shows a detailed view of a press shoe provided with elements for homogenizing the pressure in a shoe press roll.

A shoe press roll 1 (fig. 1) for use in the press section of a paper machine or other machine for treating a material web comprises a press shoe 2 with a substructure 3. The press shoe 2 can be rotated relative to the substructure by means of a turning point 4. Alternatively to the rotatable arrangement of the press shoe 2, a flexible connection to the substructure can be established, for example, by means of a specially weakened material or plastic. Furthermore, passive, i.e. non-actively controlled elements 5 are provided for homogenizing the pressure transversely to the machine direction. The element 6 is a connection to at least one yoke arranged in the shoe press roll 1, said yoke serving to increase the stability of the shoe press roll. The arrow 7 indicates the possibility of adjustment of the shoe press roll 1 in the machine direction by means of the rolling support.

The shoe press roll 1 (fig. 2) rests against the mating roll 8 during operation. A material web 9, in particular a paper web, is guided through between the shoe press roll 1 and the mating press roll 8. Starting from the turning roll 10 and on the shoe press roll 1, the material web 9 is guided, for example, on a first felt or clothing section (not shown here), while the material web 9 is guided here before, i.e. on a first press roll 11 abutting against the counter roll 8 and up to the turning roll 10 on a second felt or clothing section (also not shown here).

The shoe press roll 1 thus forms a second press roll, which rests against the mating press roll 8. The shoe press roll 1 is rotatably supported about its axis of rotation 13 on a support arm 12, for example, L-shaped. The support arm 12 is supported with its axis of rotation 13 on a machine frame (not shown). By means of an adjustment unit 14 acting on the support arm 12 and designed as a hydraulic cylinder, the shoe press roll 1 can be moved between an operating position, in which it presses against the cooperating press roll 8, e.g. a yankee drying cylinder, and a deactivated position, in which the shoe press roll 1 does not press against the cooperating press roll 8. In the operating position, a press nip is formed between the shoe press roll 1 and the counter roll 8, through which press nip the material web 9 is guided. The press roll 11 may also be provided in a similar manner with an adjusting mechanism for setting the press nip between it and the mating roll 8.

According to one embodiment, the press shoe 2 (fig. 3) in the shoe press roll 1 is equipped with two

elements

15, 16, which are rotatable each and supported in the interior of the shoe press roll 1, for homogenizing the press pressure, wherein the number of

elements

15, 16 can be chosen to be different. The

elements

15, 16 have different stiffness depending on the direction of the force. Whereby different reaction forces or softness can be achieved. By zoning the

elements

15, 16, it is possible to apply more or less nip load and thus nip load in a targeted manner to the nip formed between the shoe 2, for example made of polyurethane blocks, and the shoe press roll 1. This is very important especially in the edge areas where the press roll 8 and the material web 9 are fitted. In order to apply a uniform pressing pressure to the mating press roll 8, a hydraulic punch may also be used inside the shoe press roll 1. Preferably, the hydraulic cylinder may also be mounted at a distance of 10cm with respect to the edge of the shoe press roll 1. It is also possible to provide a plurality of hydraulic cylinders as supports, which may for example have a distance of about 10cm from one another. The pressing pressure may be applied continuously. Multiple hold-down elements may be eliminated.

According to the invention, the press roll, in particular the shoe press roll 1, has a diameter of 770mm, for example. A diameter of 1100mm may be used with sufficient installation space or for wider machines. The shoe press roll 1 can be installed as a normal shoe press arrangement, i.e. with an upstream dewatering element, such as a suction box or a suction reversing roll.

The shoe press roll 1 is used according to the invention as a second press in the double press unit shown in fig. 2, because of its compact structure, diameter 770mm, as a pivotable unit in case of using a pivoting arm or supporting arm 13.

According to the invention, the material web 9 is applied to the co-operating press roll 8 by a first press roll 11, preferably designed as a suction press roll, and heated by the co-operating press roll 8, designed as a drying cylinder, before reaching the second nip formed with the shoe press roll 1, in order to reach a maximum dry weight content.

Claims

1. A machine for producing or processing a material web (9), in particular a paper, cardboard or tissue web, with a press unit comprising a press roll (1) and a cooperating press roll (8), wherein the press roll (1) is supported on a pivotable support arm (12) and is movable by means of at least one adjustment unit (14) between an operating position, in which the press roll (1) is pressed against the cooperating press roll (8), and a deactivated position, in which the press roll (1) is not pressed against the cooperating press roll (8),

it is characterized in that the preparation method is characterized in that,

the press unit is a double press unit and the press roll (1) supported on a pivotable supporting arm (12) is arranged as a second press roll (1) in the web travel direction of the material web (9) and can be pressed in order to generate a predefined press pressure in the press nip.

2. The machine in accordance with claim 1, wherein,

it is characterized in that the preparation method is characterized in that,

the second press roll (1) is configured as a shoe press roll.

3. The machine in accordance with claim 2, wherein,

it is characterized in that the preparation method is characterized in that,

the shoe press roll (1) has a rotatably mounted press shoe (2) or a press shoe (2) arranged in a flexible connection.

4. The machine according to claim 2 or 3,

it is characterized in that the preparation method is characterized in that,

the shoe press roll (1) has, in particular in the edge region, a press shoe (2) divided into a plurality of individually supported or controllable regions or regions of different hardness.

5. The machine of one of claims 2 to 4,

it is characterized in that the preparation method is characterized in that,

the shoe press roll (1) has at least one yoke over its length for supporting the press shoe (2).

6. The machine of one of claims 2 to 5,

it is characterized in that the preparation method is characterized in that,

a dewatering element, in particular a suction box or a suction reversing roll, is arranged in front of the second press roll (1) in the web travel direction of the material web (9).

7. The machine of one of claims 1 to 6,

it is characterized in that the preparation method is characterized in that,

the second press roll (1) has a diameter of at least 750 mm.

8. The machine of one of claims 1 to 7,

it is characterized in that the preparation method is characterized in that,

the second press roll (1) is rotatable in the machine running direction or counter to the machine running direction.

9. The machine according to one of claims 1 to 8,

it is characterized in that the preparation method is characterized in that,

for a press unit comprising said cooperating press roll (8), a first press roll (11) configured as a suction press roll is arranged in front of the second press roll (1) in the web travel direction of the material web (9).

10. The machine according to one of claims 1 to 9,

it is characterized in that the preparation method is characterized in that,

the cooperating press roll (8) is a drying cylinder, in particular a yankee drying cylinder (2) or a levelling cylinder.