Shoe press

Abstract

The invention relates to a machine for manufacturing or processing a material web (9), in particular a paper, cardboard, or tissue web, said machine being equipped with a pressing unit having a press roll (1) and a counter-press roll (8), wherein the press roll (1) is mounted on a pivotable mounting lever (12) and can be moved by means of at least one adjusting unit (14) between an operating position in which the press roll (1) is pressed against the counter-press roll (8) and an inoperative position in which the press roll (1) is not pressed against the counter-press roll (8). The press roll is designed as a shoe press roll comprising a press shoe which forms a press nip with the counter-press roll (8). The press shoe is mounted inside the shoe press roll on at least one soft support element, which in turn rests on at least one yoke, and the pressing force between the counter-press roll and the press shoe can be controlled by means of the mounting lever (12).

Description

[0001] The invention relates to a machine for producing or processing a material web, in particular a paper, cardboard or tissue web, with a press unit comprising a press roll and a counter-press roll according to the preamble of patent claim 1.

[0002] Tissue paper machines, for example, have a press unit formed by a press roll and a counter-press roll designed as a drying cylinder. The press roll is often pivotally mounted relative to the counter-press roll on a support lever, so that the press roll can be moved by at least one adjustment unit acting on the support lever between an operating position, in which the press roll is pressed against the counter-press roll, and an inoperative position, in which the press roll is not pressed against the counter-press roll. Typically, the adjustment unit is designed as a hydraulic cylinder.

[0003] EP 1 925 723 A1 already discloses such a tissue paper machine, which comprises a press unit comprising at least one press roll and a counter-press roll. The press roll is mounted on a pivotable support lever and is movable by means of at least one adjustment unit acting on the support lever between an operating position in which the press roll is pressed against the counter-press roll and an inoperative position in which the press roll is not pressed against the counter-press roll. The known machine comprises an adjustment unit with a locking device by means of which the adjustment unit can be mechanically locked in the operating position.

[0004] If the press roller is to be pivoted from the operating position to the non-operating position, the mechanical locking device created by the locking device can be released again in order to be restored at a later time when the press roller has been pivoted back into the operating position.

[0005] EP 1 970 488 A1 also discloses a press arrangement with a press roll that can be pivoted toward and away from a counter roll via a lever pivotally mounted on a frame, wherein the lever can be adjusted between its pivoted-in position and its pivoted-away position via an adjusting device. The press roll is connected to the lever via connecting elements, at least one of which is arranged such that, when the lever assumes its pivoted-away position, it lies vertically above the center of gravity of the press roll pivoted away from the counter roll. EP 1 970 488 A1 also discloses that a self-pressing deflection compensating roll having an elastic jacket is formed with an internal jacket stroke. The counter roll can be formed by a drying cylinder, in particular a Yankee drying cylinder.

[0006] DE 42 16 264 C2 discloses a press device in which a paper web passes through two press nips formed by two press rolls and a common counter roll, through which the paper web can pass one after the other along with a felt. Instead of using a single felt, two different felts or dryer fabrics can also be used.

[0007] DE 19514142 C1 discloses a shoe press arrangement, wherein the press shoe is mounted within the shoe press roll on at least one soft support element, which in turn rests on at least one yoke.

[0008] The object of the present invention is to create a machine of the type mentioned above, in which the aforementioned disadvantages are eliminated, in which, on the one hand, the exact operating position of the press unit comprising a press roller and a counter-press roller is maintained, with the press roller constantly resting against the counter-press roller. This eliminates the need for constant force applied to an adjustment unit, and, at the same time, eliminates the need for complex locking mechanisms.

[0009] This problem is solved by the features of patent claim 1. According to the invention, the press shoe is mounted within the shoe press roll on at least one soft, elastically flexible support element, which in turn rests on at least one yoke. The pressing pressure between the counter-press roll and the press shoe can be controlled by means of the mounting lever.

[0010] The advantage of the invention is that a locking unit for actively pressing the press shoe against the counter roll, for example, via a hose clamp or hydraulic pistons, as provided in the prior art, is no longer required. Instead, the linear force in the press nip or press gap with the counter roll can be continuously adjusted via the oil pressure of the hydraulic medium, i.e., in the hydraulic cylinders of the bearing levers, by controlling or regulating the pressing pressure in the press gap exclusively through the lever clamp. According to the invention, a constant application of force is therefore required.

[0011] The machine according to the invention for producing or processing a material web has a press unit comprising at least one press roller and a counter-press roller, wherein the press roller is mounted on a pivotable support lever and is movable by means of at least one adjusting unit acting on the support lever between an operating position in which the press roller is pressed against the counter-press roller and an inoperative position in which the press roller is not pressed against the counter-press roller.

[0012] Advantageous embodiments of the invention are specified in the subclaims.

[0013] According to the invention, the use of an adjustment unit comprising a locking device, by means of which the adjustment unit can be mechanically locked in the operating position, is avoided. Instead, an adjustment unit comprising at least one hydraulic cylinder is used to adjust the operating line force between the press shoe and the counter roll, for example, a drying cylinder, during operation via its oil pressure. According to the invention, the use of a locking lever is thus avoided and the design of the press roll is simplified.

[0014] According to the invention, the operating positions are flexibly adjustable, with each of the press rollers and the counter-press roller being pressed against each other to varying degrees. It goes without saying that the press roller can be pivoted away from the counter-press roller for decommissioning or for performing maintenance measures.

[0015] Because the press roller is mounted on a soft, elastically yielding and flexible support element, the press shoe can be pressed against the contour of the counter roller, for example a Yankee cylinder, with the same contact pressure across its entire width in order to close the nip between the press shoe and the counter roller. The invention thus features precise adaptation to the contour of the counter roller, which can change during operation due to the influence of temperature. Due to the yielding and soft structure of the support element, the contact pressure of the press shoe is continuously adjusted and adapted. The invention thus achieves a uniformity of the contact pressure in the press nip across the entire width of the press roller, which is not achievable with the prior art.

[0016] The invention offers the advantage that the pressure system and the movement system of the shoe press are combined in a single system. No safety control or monitoring of the line force is required. Rather, a shoe press roll controlled according to the invention can be treated like a conventional press roll, with press levers actuated by actuators acting externally on the shoe press roll; the maximum line load is secured via the oil pressure in the actuators or hydraulic cylinders. Hydraulic zone control of the press shoe is also not required; rather, a single lubrication unit for the press sleeve surrounding the press shoe is sufficient. The simple design of the shoe press roll without an internal adjustment mechanism saves costs.

[0017] The distance between the shoe press roll and the counter roll can be adjusted as required, whereas with internal support sources, the stroke is limited by the sleeve to a distance of approximately 20 to 30 mm. This small distance can lead to clothing damage if the counter roll is hot.

[0018] According to the invention, a smaller deformation of the press shell and the press sleeve of the shoe press roll is made possible, whereas the shell of the shoe press roll is bulged or deformed by the stroke of an active internal pressure system according to the prior art. This means that according to the invention, deformations in the contour of the counter roll, for example the Yankee cylinder, which arise, for example, due to the influence of temperature during operation, are compensated for by the elasticity of the support element. Thus, if the shell surface of the counter roll assumes a convex or concave shape during operation, this change in shape is compensated for by the correspondingly deforming support element in such a way that the press shoe always rests against the counter roll in the press nip with the same contact pressure. The pressing pressure is preferably regulated.The humidity and / or temperature of the material web can preferably be selected as the control variable for determining the pressing pressure.

[0019] According to the invention, instead of a single support element, a plurality of support elements arranged next to one another can be provided, which are preferably connected to one another.

[0020] A further advantage of the pivotable shoe press roll according to the invention is that no change in nip force occurs when the diameter of the counter roll, for example the Yankee cylinder, changes.

[0021] According to a particularly advantageous embodiment, it is provided that by rotating the yoke together with the press shoe in or against the machine direction, the pressing pressure profile can be changed in the machine direction and thus the drainage process can be optimized.

[0022] An advantageous embodiment for adjusting the pressing pressure profile is one in which the shoe press roller has a rotatably mounted pressure shoe or a pressure shoe arranged in a flexible connection.

[0023] It is also advantageous if the shoe press roll has a plurality of individually mounted support elements. These can have different hardnesses, particularly at the two edges in edge zones, in order to improve the contact pressure of the press shoe against the counter-press roll. In this case, the counter-press roll is preferably a Yankee cylinder. The edge regions each have a width of less than 500 mm, preferably less than 300 mm. According to one embodiment, the machine according to the invention is characterized in that the press unit is a double press unit and that the press roll mounted on the pivotable support lever is arranged as the second press roll in the web travel direction of the material web.

[0024] It is also advantageous that a dewatering element, in particular a suction box or a suction turning roller, is arranged upstream of the second press roller in the web running direction of the material web.

[0025] According to an advantageous embodiment of the invention, the second press roller has a diameter of less than 1100 mm, in particular in the range between 700 mm and 1000 mm. Particularly preferably, the second press roller has a diameter of no more than 750 mm.

[0026] It is also advantageous if, in the direction of travel of the material web, a first press roll configured as a suction press roll is arranged upstream of the second press roll in the press unit comprising the counter-press roll. Preferably, the second press roll is configured as a shoe press roll.

[0027] It is particularly advantageous to provide a drying cylinder, in particular a Yankee drying cylinder, or a Yankee cylinder as the counter-press roll.

[0028] The invention is explained in more detail below using exemplary embodiments based on the following drawings. They show: Fig. 1 schematic representation of a shoe press roll which can be used according to the invention and which is adjacent to a counter roll and Fig. 2 a shoe press roll which can be adjusted to another counter roll by means of a bearing lever and has a first press roll in front of it.

[0029] A shoe press roll 1 ( Fig. 1 ) for use in a press section of a paper machine or other machine for processing a material web in a shoe press unit has a shell 1' with a very smooth paper-contacting surface 1.1 and a less smooth shoe-contacting inner surface 1.2. The shell 1' rotates around a shoe press unit, with the press shoe 2 being supported by a yoke 3, while the shell 1' rotates around the shoe 2 and the yoke 3. A counter-roller 4 is provided as the counter-pressing element. A material web 5, for example a paper web, runs through the press nip and thus comes into contact with the very smooth outer surface 1.1 of the shell 1'. It is also possible for a press felt 6 to be arranged between the material web 5 and the counter-roller 4. For example, the inner side 1.2 of the shell 1' is less smooth, i.e. has a roughness >10 µm.

[0030] Opposite the yoke 3, the press shoe 2 is mounted on at least one flexibly yielding support element 7 extending transversely to the machine running direction, which can be compressed in certain areas in such a way that it compensates for fluctuations in the outer diameter of the counter roll 4.

[0031] The shoe press roll 1 ( Fig. 2 ) rests against a counter-roller 8 during operation. A material web 9, in particular a paper web, is guided between the shoe press roll 1 and the counter-press roll 8. From a deflection roll 10 and over the shoe press roll 1, the material web 9 is guided, for example, over a first (not shown here) felt strand or clothing strand, while the material web 9 is guided beforehand, ie over a first press roll 11 resting against the counter-cylinder 8, and up to the deflection roll 10 over a second (also not shown) felt strand or clothing strand.

[0032] The shoe press roll 1 thus forms the second press roll, which rests against the counter-press roll 8. The shoe press roll 1 is mounted on an, for example, L-shaped bearing lever 12 so as to be rotatable about its axis of rotation 13. The bearing lever 12 has its axis of rotation 13 mounted on a machine frame (not shown). By means of an adjusting unit 14 acting on the bearing lever 12 and designed as a hydraulic cylinder, the shoe press roll 1 can be moved between an operating position in which it is pressed against the counter-press roll 8, for example a Yankee drying cylinder, and an inoperative position in which the shoe press roll 1 is not pressed against the counter-press roll 8. In the operating state, a press nip is formed between the shoe press roll 1 and the counter-press roll 8, through which the material web 9 is guided.The press roller 11 can also be equipped in a similar manner with an adjustment mechanism for adjusting the press nip between it and the counter roller 8. The counter roller 8 can also be heated with steam.

[0033] According to the invention, the press roll, in particular the shoe press roll 1, has a diameter of, for example, 770 mm. A diameter of 1100 mm can be used if sufficient space is available or for wide machines. The shoe press can be installed in a conventional shoe press configuration, i.e., with an upstream dewatering element such as a suction box or a suction reversing roll.

[0034] According to the invention, the shoe press roll 1 is used as a second press in a Fig. 2 Due to its compact design with a diameter of 770 mm, the double press unit shown is used as a pivoting unit using a pivoting or bearing lever 13.

[0035] According to the invention, the material web 9 is applied to the counter-press roll 8 by a first press roll 11, preferably designed as a suction press roll, and is heated by the counter-press roll 8, designed as a drying cylinder, before reaching the second nip formed by the shoe press roll 1, in order to achieve maximum dry contents.

Claims

1. Machine for producing or processing a material web (5, 9), in particular a paper, cardboard, or tissue web, having a pressing unit comprising a press roll and a counter-press roll (8), wherein the press roll is mounted on a pivotable mounting lever (12) and is movable by means of at least one adjustment unit (14) between an operating position in which the press roll is pressed against the counter-press roll (8) and an inoperative position in which the press roll is not pressed against the counter-press roll (8), and wherein the press roll is formed as a shoe press roll (1) with a press shoe (2) that forms a pressure nip with the counter-press roll (8), characterized in that the press shoe (2) is mounted within the shoe press roll (1) on at least one soft, elastically yielding and flexible support element (7), which in turn rests on at least one yoke (3), and in that the pressing pressure between the counter-press roll (8) and the press shoe (2) can be controlled by means of the mounting lever (12).

2. Machine according to Claim 1, characterized in that the mounting lever (12) is hydraulically controllable.

3. Machine according to Claim 1 or 2, characterized in that the pressing pressure is adjustable.

4. Machine according to Claim 3, characterized in that the humidity and / or temperature of the material web (5, 9) can be selected as the control variable for determining the pressing pressure.

5. Machine according to any one of Claims 1 to 4, characterized in that the pressing unit is a double pressing unit and that the press roll (1) mounted on the pivotable mounting lever (12) is arranged as a second press roll (1) in the web travel direction of the material web (9).

6. Machine according to Claim 5, characterized in that the second press roll (1) is formed as a shoe press roll.

7. Machine according to any one of Claims 5 to 6, characterized in that a drainage element, in particular a suction box or a suction turning roll, is arranged upstream of the second press roll (1) in the web travel direction of the material web (5, 9).

8. Machine according to any one of Claims 1 to 7, characterized in that the second press roll (1) has a diameter of less than 1100 mm, in particular in the range between 700 mm and 1000 mm, and that the second press roll (1) preferably has a diameter of not more than 750 mm.

9. Machine according to any one of Claims 1 to 8, characterized in that the second press roll (1) is rotatable in the machine running direction or counter to the machine running direction.

10. Machine according to any one of Claims 1 to 9, characterized in that in the web travel direction of the material web (5, 9), a first press roll (11) formed as a suction pressure roll is arranged upstream of the second press roll (1) of the pressing unit comprising the counter-press roll (8).

11. Machine according to any one of Claims 1 to 10, characterized in that the counter-press roll (8) is a drying cylinder, in particular a yankee drying cylinder (2), or a smoothing cylinder.

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