Press body and paper machine comprising such press body

Abstract

The invention relates to a press body for a paper machine having an extended nip formed between the press body and a counter-pressure member, in which the press body (50) is elastically deformable and comprises a working surface (15), and in which the press body comprises a first pressure chamber (51) and a second pressure chamber (52), the first pressure chamber (51) and the second pressure chamber (52) are arranged inside the pressing body (50) and separated from each other by a partition wall (55), the pressure chambers (51, 52) are configured to be pressurized such that the pressing body (50) expands in order to press the working surface (15) towards the counter pressure member, and wherein the first pressure chamber (51) has a first height (h1) and the second pressure chamber (52) has a second height (h2). The second pressure chamber (52) has a second height (h2), and wherein the first height (h1) is greater than the second height (h2). The invention also relates to a paper machine comprising such a press body.

Description

Technical Field

[0001] This invention relates to a press body for a paper machine having an extended pressure zone formed between the press body and a counter-pressure member, the press body including an internal pressure chamber. The invention also relates to a paper machine having such a press body. Background Technology

[0002] In papermaking machines, stretch press treads are typically used to press water out of newly formed wet fiber webs, but they can also be used for other purposes, such as calendering. Although stretch press treads were first introduced for heavy paper grades such as paperboard, they have also begun to be used for light paper grades such as printing paper, and even for tissue paper. When manufacturing tissue paper, the stretch press tread is typically formed by stretch press rolls and Yankee dryers that act as reverse pressure members for the stretch press rolls.

[0003] Especially in machines used for manufacturing tissue paper, the stretch press stencil is typically formed by a stretch press roll, which includes a support body with a working surface that is pressed against a counter roll via a pressure chamber located inside or below the support body. This pressure chamber is used to push the support body toward a counter pressure member in a first direction. The purpose of the stretch press stencil is to dewater the fiber web during papermaking.

[0004] In the art, rigid support bodies, typically made of metallic materials, are known. However, because rigid support bodies are non-flexible, it is difficult to achieve the desired pressure distribution in the stretching press zone. This hinders the effective dewatering of the fiber web and leads to excessive wear on components of the stretching press zone, such as the stretching press rollers and the fabric used to transport the web through the press zone.

[0005] Therefore, a softer, more flexible support body capable of elastic deformation is preferred, and dehydration can be significantly improved by achieving the desired pressure distribution against the reverse pressure member. The flexible support body typically includes at least two pressure chambers housed within the support body, and by pressurizing the pressure chambers, the working surface is pressed against the reverse pressure member.

[0006] However, a challenging area in designing and operating a flexible support body is achieving high pressure with the desired pressure distribution within the pressing zone. This is particularly challenging when at least two pressure chambers are arranged within the pressing body, as the increased pressure within the chambers causes not only deformation toward the pressing zone but also internal deformation of the partition walls between the chambers and / or the outer walls. Due to the flexible material, the support body tends to deform in unpredictable ways, thereby distorting the pressure distribution and reducing dewatering efficiency. There is also a risk of plastic deformation due to excessive pressure in one or more pressure chambers, which could damage the support body.

[0007] Therefore, improvements are needed in this area. Summary of the Invention

[0008] The object of the present invention is to eliminate or at least minimize the aforementioned problems. This is achieved by a press body for a paper machine according to the appended independent claims, and a paper machine including such a press body.

[0009] The press body according to the invention is suitable for a paper machine having an extended press zone formed between the press body and a reverse pressure member. The press body is elastically deformable and includes a working surface, and further includes a first pressure chamber and a second pressure chamber disposed within the press body and separated from each other by a partition wall. The pressure chambers are configured to be pressurized, causing the press body to expand to press the working surface against the reverse pressure member. The first pressure chamber has a first height, and the second pressure chamber has a second height, wherein the first height is greater than the second height.

[0010] The first pressure chamber having a greater height than the second pressure chamber allows for better control of pressure distribution within the pressing zone and improved pressure distribution within the pressing body. When the pressure chambers are pressurized, the expansion of the pressing body occurs through the stretching of the partition walls and the outer wall of the pressing body, and the resulting wall elongation will depend on their unstretched length. Furthermore, depending on the height of the chambers, the material thickness of the pressing body located above the pressure chambers (i.e., between the pressure chambers and the working surface) will vary. As a result, providing pressure chambers with different heights allows for better control of pressure distribution within the pressing zone, thereby adjusting the pressure distribution within the pressing zone.

[0011] Appropriately, the first and second pressure chambers are configured to be pressurized independently of each other. Furthermore, the first pressure chamber may include support elements for supporting the partition wall, the support height of which corresponds to a first height of the first pressure chamber. The support elements provide support for the wall of the first pressure chamber to prevent deformation that might otherwise occur if the pressure difference between the first and second pressure chambers is large.

[0012] Furthermore, the first height is appropriately at least equal to the sum of the second height and the maximum stroke length of the pressing body. Therefore, the first height is greater than the second height by at least the maximum stroke length. This ensures that even when the pressing body is at its maximum elongation, the second pressure chamber is prevented from expanding beyond the first pressure chamber. This is particularly advantageous for embodiments including support elements, as the risk of deformation of the partition wall is reduced or even minimized.

[0013] Appropriately, the first bottom of the first pressure chamber and the second bottom of the second pressure chamber are located at a certain bottom height from the bottom of the pressing body. Thus, the pressure chambers are arranged at a common bottom level but extend to different heights within the pressing body. Advantageously, a smaller distance is provided in the pressing body from the first pressure chamber to the working surface, compared to a larger distance from the second pressure chamber to the working surface. The greater the distance, the more uniform the pressure distribution in the material of the pressing body, thereby further adjusting the pressure distribution in the pressing zone.

[0014] Alternatively, the bottom of the first pressure chamber is located at the height of the bottom of the first chamber in the pressing body, and the bottom of the second pressure chamber is located at the height of the bottom of the second chamber in the pressing body, wherein the height of the bottom of the second chamber is equal to or greater than the sum of the height of the bottom of the first chamber and the maximum stroke length. This ensures that even during the maximum expansion of the pressing body, the second pressure chamber cannot expand downward beyond the bottom of the first pressure chamber.

[0015] In some embodiments, the first top of the first pressure chamber and the second top of the second pressure chamber are both located at a certain top height from the bottom of the press body. Thus, the pressure chambers are arranged at a common top level but extend to different depths within the press body. This facilitates achieving different heights of the pressure chambers while still maintaining both pressure chambers at equal distances from the working surface, so that the press body provides similar deformation above both pressure chambers during expansion.

[0016] Alternatively, the top of the first pressure chamber is located at the height of the top of the first chamber in the pressing body, and the top of the second pressure chamber is located at the height of the top of the second chamber in the pressing body, and the height of the top of the first chamber is equal to or greater than the sum of the height of the top of the second chamber and the maximum stroke length. This ensures that when the pressing body expands, the second pressure chamber will not expand upwards beyond the top of the first pressure chamber.

[0017] Suitablely, the maximum stroke length is at least 1 mm, preferably at least 4 mm, and more preferably at least 7 mm. Therefore, the press body can expand to meet the requirements of the paper machine in which it is arranged. Furthermore, the expansion of the press body can be achieved by stretching the partition walls between the pressure chambers due to the increased pressure inside the pressure chambers, without the risk of the partition walls plastically deforming or cracking due to excessive stretching.

[0018] In some embodiments, the maximum stroke length is at least 15 mm, preferably at least 20 mm, and more preferably at least 30 mm. Thus, a very large stroke is achieved, and the partition wall is configured to stretch to accommodate this. It is highly advantageous that the stretching of the partition wall is performed to extend the press body without excessive energy absorption, thereby ensuring the desired pressure distribution in the extended press zone.

[0019] Appropriately, the first pressure chamber has a first cross-sectional area, and the second pressure chamber has a second cross-sectional area, wherein the first cross-sectional area is different from the second cross-sectional area. Thus, different volumes of the first and second pressure chambers are achieved, enabling different pressures to enter the pressure zone even when the first and second pressure chambers are pressurized from the same pressurized fluid source.

[0020] Alternatively, the first cross-sectional area is substantially equal to the second cross-sectional area. Therefore, the widths of the first and second pressure chambers differ, making the second pressure chamber longer in the machine direction than the first pressure chamber. This provides improved control over the pressure distribution within the pressure zone.

[0021] Suitablely, the pressing body includes a third pressure chamber disposed inside the pressing body and configured to be pressurized to cause the pressing body to expand, wherein the third pressure chamber has a third height that differs from at least one of a first height and a second height. Therefore, the pressure distribution in the pressing zone can be controlled in greater detail compared to using only two pressure chambers.

[0022] Suitablely, the press body may include at least one additional pressure chamber disposed within the press body and configured to be pressurized to cause the press body to expand, wherein each of the at least one additional pressure chamber has a height different from at least one of a first height and a second height. Therefore, since the number, size, and pressurization of the additional pressure chambers can be selected to suit the specific requirements of any given application, the pressure distribution in the press zone can be controlled in greater detail.

[0023] The present invention also includes a paper machine having at least one press body according to any embodiment of the present invention.

[0024] The many additional benefits and advantages of the present invention will be readily understood by those skilled in the art from the following detailed description. Attached Figure Description

[0025] The invention will now be described in more detail with reference to the accompanying drawings, in which: Figure 1 A schematic cross-sectional view of an extended press zone of a paper machine is disclosed, wherein the extended press zone is formed between the press body and the reverse pressure member; Figure 2 A schematic cross-sectional view of the pressing body as seen from the side according to the first embodiment of the present invention is disclosed; Figure 3 A schematic cross-sectional view of the pressing body as seen from the side according to a second embodiment of the present invention is disclosed; Figure 4 A schematic cross-sectional view of the pressing body as seen from the side according to a third embodiment of the present invention is disclosed; Figure 5 A schematic cross-sectional view of the pressing body as seen from the side according to the fourth embodiment of the present invention is disclosed; Figure 6 A schematic cross-sectional view of the pressing body as seen from the side according to the fifth embodiment of the present invention is disclosed; Figure 7 A schematic cross-sectional view of the pressing body as seen from the side according to the sixth embodiment of the present invention is disclosed.

[0026] All accompanying drawings are schematic and not necessarily to scale, and generally only show parts that are helpful in explaining the corresponding embodiments, while other parts may be omitted or are merely suggested. Unless otherwise indicated, any reference numerals appearing in multiple figures refer to the same object or feature in all figures. Detailed Implementation

[0027] When the term "papermaking machine" is used herein, it should be understood as a machine suitable for producing paper from pulp. This machine can be configured to produce tissue paper, but it can also be configured to produce writing paper or paperboard. In the following text, the production of tissue paper is mentioned, but this is considered merely as an example and not as a limitation on the scope of the invention.

[0028] When terms such as “upper,” “lower,” “top,” and “bottom” are used below, they should be understood to relate to a first direction D, which can be considered an upward direction. Therefore, the upper side is the side facing the first direction D, while the lower side faces the direction opposite to the first direction D. Furthermore, the upper and lower parts are distinguished from each other by the movement towards the first direction D first passing through the bottom and then through the upper part.

[0029] It should be noted that all dimensions given in this document should be understood as being within manufacturing tolerances, or at least not differing by more than 10%. Furthermore, when it is stated that a feature is equal to, substantially equal to, constant, substantially constant, uniform, or substantially uniform with another feature, this should also be understood as being equal, constant, or uniform within manufacturing tolerances, or at least not differing by more than 10%.

[0030] Figure 1 An extended press zone N is disclosed in the paper machine 1 according to the present invention, wherein the extended press zone N is formed between the press body 50 and the reverse pressure member 7 according to any embodiment of the present invention.

[0031] A paper machine comprising an extension press N having a press body 50 according to the invention will now be described, with the description focusing on the extension press N and only a brief description of the other parts of the paper machine.

[0032] Therefore, as is known in the art, paper machines typically include a forming section in which a headbox is arranged to inject pulp into the gap between the forming fabric and the felt 33. The forming fabric is typically a foraminouswire. The felt is configured to pass through the forming roll, and the felt and the forming fabric are guided into a loop by guide rolls.

[0033] The newly formed wet fiber web is transported from the forming section by felt 33 to... Figure 1 The extended pressing zone N shown is formed between the extended pressing roller 5 and the reverse pressure member 7. The extended pressing roller 5 includes a pressing body 50 according to the invention, which will be described in further detail below. The reverse pressure member 7 may suitably be a Yankee dryer, but in some embodiments, the extended pressing zone may be arranged between the extended pressing roller 5 and another reverse pressure member 7 before being conveyed to the Yankee dryer.

[0034] In the press zone N between the stretch press rolls and the reverse pressure member 7, water is pressed out from the web W and absorbed by the felt 33 used to receive water. The web W then passes through a Yankee dryer 7 and is dried by heat spreading from the Yankee dryer 7 to the web W. The Yankee dryer 7 is typically heated to a temperature of approximately 95-100°C on the surface in contact with the web W. The dry solids content of the web W upon reaching the stretch press zone N can vary significantly, but in typical applications, it is in the range of 18-30%. Depending on factors such as the linear load in the press zone, the temperature of the reverse pressure member 7, and the dry solids content of the web W before reaching the stretch press zone N, the web W can have a dry solids content of 40-55% after the stretch press zone N.

[0035] The web material W is typically scraped off from the Yankee dryer 7 by a doctor blade and then fed to the rewinder as dried web material.

[0036] The above description is considered a general description of the paper machine 1. However, it should be noted that the press body 50 according to the invention can be used in various paper machines, as long as the paper machine has an extended press zone between the press body and the reverse pressure member.

[0037] Now we will refer to it again. Figure 1 A more detailed description of the extended press trommel N is provided in the figure, which shows an extended press trommel roller 5 comprising a flexible sheath 10 having an inner surface 11 and an outer surface 12. The flexible sheath 10 typically comprises polyurethane and is shaped as a tube extending in the machine transverse direction, which is the same as the machine direction MD (see [reference needed]). Figure 2 The vertical direction, the machine direction is defined as the direction from the forming section to the winding machine, that is, the main travel direction of the web W.

[0038] Therefore, the axial direction of the flexible sleeve 10 is aligned with the transverse direction of the machine, and the flexible sleeve 10 is typically connected to an end wall at its axial end, which is rotatably arranged about an axis, allowing the extension pressing roller 5 to rotate. Suitable, the extension pressing roller 5 can be connected to a pressurized air source, so that the enclosed space formed by the flexible sleeve 10 and the end wall can be filled with pressurized air.

[0039] Inside the extended pressing roller 5, a support member 21 is installed, which holds the pressing body 50 according to the invention such that the upper surface 14 of the support body 50 presses against the inner surface 11 of the flexible sheath 10. Working surface 15 (see below) Figure 2 Located on the upper surface 14, this working surface forms an extended press zone N by pressing against the flexible sheath 10, such that the web W presses against the reverse pressure member 7. The press body 50 is elongated and extends along the inner surface 11 of the extended press roller 5 in a direction transverse to the rotation direction of the extended press roller 5, so as to press against the entire width of the web W in the extended press zone N. For this purpose, the length of the press body 50 may be equal to or greater than the target width of the web W, but in some embodiments, the length of the press body 50 may instead be shorter than the target width of the web W.

[0040] The working surface 15 is a surface used to form the extended press zone N. The shape of the working surface 15 can be adapted to form a desired press distribution with the reverse pressure member 7, as is known in the art. A prior art design for processing the working surface is US2009 / 0173465 (Metso Paper). Despite the preceding... Figure 2The working surface 15 is schematically shown as a flat surface, but it should be noted that any shape and design of the working surface is applicable to the press body 50 of the present invention.

[0041] The following will be from Figure 2 The first embodiment shown begins with a detailed description of the press body 50. For other embodiments of the invention, features that differ from one another will be described primarily to avoid repetition. Therefore, it should be understood that all features not specifically described as different between different embodiments should be considered similar or identical. Moreover, features from one embodiment can be freely combined with those in another technically feasible embodiment.

[0042] The press body 50 includes a first pressure chamber 51 and a second pressure chamber 52 separated from each other by a partition wall 55. Each of the first pressure chamber 51 and the second pressure chamber 52 is configured to be pressurized by fluid connection to a pressurized fluid source, as known in the art. The pressurized fluid is suitably a hydraulic fluid (e.g., oil), but in some embodiments other fluids may be used instead.

[0043] The press body 50 is made of an elastically deformable material, which causes the press body 50 to expand when the first pressure chamber 51 and the second pressure chamber 52 are pressurized. During use, the press body 50 is mounted in the support 21 (see...). Figure 1 The pressing body 50 can mainly follow the Figure 2 The pressure chamber expands in the first upward direction D. This expansion causes the working surface 15 on the upper side 14 of the press body 50 to be pressed against the reverse pressure member 7, thereby forming a pressure zone N. The partition wall 55 between the first pressure chamber 51 and the second pressure chamber 52 has a wall thickness t of 1 mm to 20 mm.

[0044] The first pressure chamber 51 has a first height h1, and the second pressure chamber 52 has a second height h2, wherein the first height h1 is greater than the second height h2. Furthermore, the first pressure chamber 51 has a first cross-sectional area A1, and the second pressure chamber 52 has a second cross-sectional area A2. In a first embodiment, the first cross-sectional area A1 is greater than the second cross-sectional area A2, but in other embodiments, conversely, the first cross-sectional area A1 is smaller. Alternatively, the cross-sectional areas A1 and A2 may be equal (see [link to relevant documentation]). Figure 6 ).

[0045] Preferably, the press body 50 is elastically deformable by being made of a material having a Shore A hardness of 50-100, preferably 80-100, and more preferably 90-95. When Shore A hardness is mentioned herein, it will be understood according to ASTM D2240. The press body 50 may also comprise more than one material, wherein at least one material has a Shore A hardness as described above. A suitable material is polyurethane.

[0046] During use, the first pressure chamber 51 and the second pressure chamber 52 are pressurized to cause the press body 50 to expand. Figure 2 In the first embodiment, the first pressure chamber 51 and the second pressure chamber 52 are configured to be pressurized individually to different pressures, or together to similar or the same pressure.

[0047] As the press body 50 expands, the partition wall 55 stretches as the height of the first pressure chamber 51 and the second pressure chamber 52 increases. Depending on one or more materials used in the press body 50, the thickness of the partition wall 55, and the pressure inside the chambers, the partition wall 55 and the sidewalls 57 at the outer ends of the press body 50 stretch in the machine direction MD to accommodate the expansion. The dimensions of the partition wall 55 are selected to allow it to stretch to the maximum stroke length SL of the press body 50 to enter the pressing zone N, and also to provide stability to the press body 50. In particular, when the first pressure chamber 51 and the second pressure chamber 52 are pressurized to different pressures, there is a risk that the partition wall 55 may deform and protrude into the pressure chamber at a lower pressure.

[0048] The pressure inside the first pressure chamber 51 can be equal to the pressure inside the second pressure chamber 52, or alternatively, they can be different. Depending on the desired specific pressure distribution in the pressing zone N, it is advantageous to have a lower pressure in the first pressure chamber 51 and a higher pressure in the second pressure chamber 52. Thus, the press body 50 is arranged in the machine direction MD such that the second pressure chamber 52 is located after the first pressure chamber 51, so that when the web W moves through the pressing zone N, the web first experiences the lower pressure from the first pressure chamber 51, and then the higher pressure from the second pressure chamber 52.

[0049] In an embodiment of the present invention, the first pressure chamber 51 and the second pressure chamber 52 are pressurized separately, and they may be referred to as the low-pressure chamber and the high-pressure chamber, respectively.

[0050] Figure 3 A second embodiment of the press body 50 is disclosed, which includes a support element 54 disposed within a first pressure chamber 51. The support height SH of the support element 54 corresponds to a first height h1 of the first pressure chamber 51, such that the support element 54 extends from the bottom to the top of the first pressure chamber 51. Figure 3 In this embodiment, the support element 54 is shown only along the partition wall 54, but in some embodiments, the support element 54 may alternatively have other shapes and designs, as long as it is able to support the partition wall 55 and prevent stretching or deformation in directions other than the first direction D (e.g., see...). Figure 4Especially when the first pressure chamber 51 and the second pressure chamber 52 are individually pressurized to a lower pressure in the first pressure chamber 51 than in the second pressure chamber 52, the support element 54 is advantageous in preventing such deformation. In the above-described case, the partition wall 5 is at risk of deformation in the lateral direction from the second pressure chamber 52 toward the first pressure chamber 51 (i.e., in a direction parallel to the machine direction MD and perpendicular to the first direction D). When using the press body 50, the expansion caused by the pressurized pressure chambers 51, 52 should occur only in the first direction D, and when the press body 50 is placed in the retainer 21 of the paper machine 1, the support element 54 ensures that this is the only available direction.

[0051] In addition, Figure 3 In the second embodiment, the first height h1 is at least equal to the sum of the second height h2 and the maximum stroke length SL of the press body 50. This means that the press body 50 can expand its maximum stroke length SL in the first direction D, while the second pressure chamber 52 does not extend beyond the first height h1, and since the first height corresponds to the height of the support element 54, there will be support for the partition wall 55 even at the maximum stroke length SL. This is highly advantageous in protecting the partition wall 55, thereby increasing the lifespan of the press body 50 and reducing the need for maintenance.

[0052] In the second embodiment, the first pressure chamber 51 has a first bottom b1 located at a first chamber bottom height bh1 in the pressing body 50, and the second pressure chamber 52 has a second bottom b2 located at a second chamber bottom height bh2. The second chamber bottom height bh2 is equal to or greater than the sum of the first chamber bottom height bh1 and the maximum stroke length SL. This means that if the expansion of the pressing body 50 causes the second pressure chamber 52 to expand at bottom b2, the support element 54 will be able to support the partition wall 55 and prevent deformation from entering the first pressure chamber 51.

[0053] The bottom height bh1 of the first chamber and the bottom height bh2 of the second chamber are determined relative to the bottom B of the pressing body 50.

[0054] Furthermore, the first pressure chamber 51 has a first top t1, and the second pressure chamber 52 has a second top t2, and they have substantially equal top heights TH from the bottom B of the press body.

[0055] In all embodiments of the invention, it is advantageous for the shape of the support element 54 to correspond to the shape of the partition wall 55, as this allows for reliable support of the partition wall 55.

[0056] Figure 4A third embodiment is shown, which differs from the second embodiment in that the top t1 of the first pressure chamber 51 is located at a first chamber top height th1 in the pressing body 50, and the top t2 of the second pressure chamber 52 is located at a second chamber top height th2 in the pressing body 50. The first chamber top height th1 is equal to or greater than the sum of the second chamber top height th2 and the maximum stroke length SL. This makes the material thickness between the first pressure chamber 51 and the working surface 15 different from the material thickness between the second pressure chamber 52 and the working surface 15. This also means that if the expansion of the pressing body 50 causes the second pressure chamber 52 to expand at top t2, the support element 54 will be able to support the partition wall 55 and prevent deformation from entering the first pressure chamber 51.

[0057] In the third embodiment, the first bottom b1 and the second bottom b2 are located at a bottom height bh that is substantially equal to the bottom B of the pressing body 50.

[0058] The third embodiment also illustrates a different design for the support element 54, namely, by extending the support element along the partition wall 55 and along the opposing wall of the first pressure chamber 51, and by using spacers along these two walls to maintain a fixed distance from each other, thereby further increasing stability at the partition wall 55. This facilitates maintaining the alignment of the support element 54 along the partition wall 55, regardless of how the partition wall 55 moves during the expansion of the press body 50.

[0059] Aside from the design of the support element 54, the main difference between the second and third embodiments lies in the placement of the first pressure chamber 51 and the second pressure chamber 52 relative to each other. This depends on whether the elongation of the partition wall 55 occurs at the top t1, t2 or at the bottom b1, b2 of the pressure chambers 51, 52. Figure 3 and Figure 4 The embodiment is able to prevent lateral deformation of the partition wall due to the height difference between the first pressure chamber 51 and the second pressure chamber 52 and their arrangement relative to each other.

[0060] Figure 5A fourth embodiment is disclosed, in which the advantages of the second and third embodiments are combined, namely, the height difference between the first pressure chamber 51 and the second pressure chamber 52 is such that the first height h1 is at least equal to the second height h2 plus twice the maximum stroke length SL. This means that elongation or stretching of the partition wall 55 can occur at the top, bottom, or both, without the risk of the partition wall 55 deforming into the first pressure chamber 51, because the support element 54 will be able to cover such elongation or stretching. Furthermore, by arranging the second pressure chamber 52 without aligning it with the first top t1 or first bottom b1 of the first pressure chamber 51, greater freedom is achieved in selecting the placement of the second pressure chamber 52 to control the desired pressure distribution in the pressure zone N.

[0061] In all embodiments of the present invention, the maximum stroke length SL is at least 1 mm to ensure that the press body 50 can expand into the press zone N as needed. Preferably, the maximum stroke length SL is at least 4 mm, more preferably at least 7 mm. Providing a larger maximum stroke length increases the versatility of the press body 50, as it can be designed for use in different papermaking machines producing different grades of tissue paper or other paper. In some applications of the present invention, the maximum stroke length is at least 15 mm, more preferably at least 20 mm, and even more preferably at least 30 mm. This ensures that the press body 50 can be used in a variety of papermaking machines for producing any kind of web from lignocellulosic materials.

[0062] By selecting the dimensions of the first pressure chamber 51 and the second pressure chamber 52 to ensure that the partition wall 55 can be stretched to the desired maximum stroke length without damage, a design is achieved that enables the press body 50 to perform a longer maximum stroke length SL. When the press body 50 is used in the paper machine 1, the desired stroke is achieved by pressurizing the first pressure chamber 51 and the second pressure chamber 52.

[0063] Figure 6 A fifth embodiment of the pressing body 50 is disclosed, wherein a third pressure chamber 53 is added inside the pressing body 50. Similar to the first pressure chamber 51 and the second pressure chamber 52, the third pressure chamber 53 is configured to be pressurized individually or together with at least one of the first pressure chamber 51 and the second pressure chamber 52 to cause the pressing body 50 to expand. The third pressure chamber has a third height h3 that is different from at least one of the first height h1 and the second height h2. Figure 6In the diagram, the third pressure chamber 53 is shown having a third height h3 substantially equal to the first height h1. Furthermore, the dimensions of the partition wall 55 on either side of the third pressure chamber 53 can be designed to allow for stretching to a desired maximum stroke length SL, while providing stability to reduce deformation when pressure chambers 51, 52, and 53 are individually pressurized. The third pressure chamber 53 may also include at least one support element 54 to support one or both of the adjacent partition walls 55 during expansion.

[0064] In the fifth embodiment, the first cross-sectional area A1 of the first pressure chamber 51 is substantially equal to the second cross-sectional area A2 of the second pressure chamber 52. The third pressure chamber 53 has a third cross-sectional area A3, which may be substantially equal to the first cross-sectional area A1 or may vary as needed. Moreover, although the third pressure chamber 53 is shown with its top and bottom at substantially the same height as the first top t1 and the first bottom b1, this may also be varied as needed.

[0065] Figure 7 A sixth embodiment of the press body 50 is disclosed, comprising a third pressure chamber 53 and an additional pressure chamber 56 having an additional height ha different from at least one of the first height h1 and the second height h2. This is to illustrate how the number of pressure chambers 51, 52, 53, and 56 can be selected to include any suitable number, thereby achieving greater control over the pressure distribution in the pressing zone. The size of the partition wall 55 can also be selected as needed, depending on the number of pressure chambers 51, 52, 53, and 56 and the pressure during use, thereby achieving the flexibility required for stretching and the stability required to minimize deformation. Furthermore, although only the third pressure chamber 53 is shown in the sixth embodiment as having a support element 54, it should be noted that support elements 54 can be provided in any one or all of the pressure chambers 51, 52, 53, and 56 as needed.

[0066] It should be noted that the features from the various embodiments described herein can be freely combined unless explicitly stated that such combination is inappropriate.

Claims

1. A press body for a paper machine, the paper machine having an extended pressure zone formed between the press body and a reverse pressure member, wherein, The pressing body (50) is elastically deformable and includes a working surface (15), wherein the pressing body includes a first pressure chamber (51) and a second pressure chamber (52), the first pressure chamber and the second pressure chamber are arranged inside the pressing body (50) and separated from each other by a partition wall (55), the pressure chambers (51, 52) are configured to be pressurized such that the pressing body (50) expands to press the working surface (15) against the reverse pressure member, wherein the first pressure chamber (51) has a first height (h1) and the second pressure chamber (52) has a second height (h2), wherein the first height (h1) is greater than the second height (h2).

2. The pressing body according to claim 1, wherein, The first pressure chamber (51) and the second pressure chamber (52) are configured to be pressurized independently of each other, and wherein the first pressure chamber (51) includes a support element (54) for supporting the partition wall (53), the support height (SH) of the support element (54) corresponding to the first height (h1) of the first pressure chamber (51).

3. The pressing body according to claim 1 or 2, wherein, The first height (h1) is at least equal to the sum of the second height (h2) and the maximum stroke length (SL) of the press body (50).

4. The pressing body according to any one of claims 1 to 3, wherein, The first bottom (b1) of the first pressure chamber (51) and the second bottom (b2) of the second pressure chamber (52) are both located at a bottom height (BH) that is substantially equal to the bottom (B) of the press body (50).

5. The pressing body according to any one of claims 1 to 3, wherein, The bottom (b1) of the first pressure chamber (51) is located at the bottom height (bh1) of the first chamber in the pressing body, and the bottom (b2) of the second pressure chamber (52) is located at the bottom height (bh2) of the second chamber in the pressing body (50), wherein the bottom height (bh2) of the second chamber is equal to or greater than the sum of the bottom height (bh1) of the first chamber and the maximum stroke length (SL).

6. The pressing body according to any one of claims 1 to 3 or 5, wherein, The first top (t1) of the first pressure chamber (51) and the second top (t2) of the second pressure chamber (52) are both located at a top height (TH) that is substantially equal to the bottom (B) of the press body (50).

7. The pressing body according to any one of claims 1 to 5, wherein, The top (t1) of the first pressure chamber (51) is located at the first chamber top height (th1) in the pressing body (50), and the top (t2) of the second pressure chamber (52) is located at the second chamber top height (th2) in the pressing body (50), and the first chamber top height (th1) is equal to or greater than the sum of the second chamber top height (th2) and the maximum stroke length (SL).

8. The pressing body according to any one of claims 3 to 7, wherein, The maximum stroke length (SL) is at least 1 mm, preferably at least 4 mm, and more preferably at least 7 mm.

9. The pressing body according to claim 8, wherein, The maximum stroke length (SL) is at least 15 mm, preferably at least 20 mm, and more preferably at least 30 mm.

10. The pressing body according to any one of the preceding claims, wherein, The first pressure chamber (51) has a first cross-sectional area (A1) and the second pressure chamber (52) has a second cross-sectional area (A2), wherein the first cross-sectional area (A1) is different from the second cross-sectional area (A2).

11. The pressing body according to any one of claims 1 to 9, wherein, The first cross-sectional area (A1) is substantially equal to the second cross-sectional area (A2).

12. The pressing body according to any one of the preceding claims further includes a third pressure chamber (53), said third pressure chamber being disposed inside the pressing body (50) and configured to be pressurized to cause the pressing body (50) to expand, wherein, The third pressure chamber (53) has a third height (h3) that is different from at least one of the first height (h1) and the second height (h2).

13. The pressing body according to claim 12, further comprising at least one additional pressure chamber (56), said at least one additional pressure chamber being disposed within the pressing body (50) and configured to be pressurized to cause the pressing body (50) to expand, wherein, Each of the at least one additional pressure chamber (56) has a height (ha) different from at least one of the first height (h1) and the second height (h2).

14. A paper machine comprising at least one press body (50) according to any one of the preceding claims.

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