PRESS DEVICE HAVING AN EXTENDED PRESS NIP FOR PRESSING A TRAVELING PAPER OR BOARD WEB

Description

Technical field

[0001] The present invention relates to a press device having an extended nip intended for pressing a running paper or paperboard web. More specifically, the invention relates to a shoe press of the type which comprises a support which supports a press shoe adjacent to a counter roll or another backing member in such a way that the press shoe and the backing member form an extended nip between themselves, and which furthermore comprises a hydraulic or pneumatic arrangement for urging the press shoe toward the backing member in order to apply a pressure onto the web passing through the nip.

[0002] The press device according to the invention particularly advantageously can be utilised for wet-pressing of moist paper or paperboard webs, but also for calendering or other finishing of dried paper or paperboard. The press device according to the invention can also be utilised for other fibre webs than paper and paperboard.

Background of the invention

[0003] Since a long time, shoe press devices, i.e. presses having an extended nip, have been utilised when manufacturing different paper and paperboard grades, primarily for wet-pressing in order to increase the dryness of the web, but also for calendering and other finishing in order to improve surface properties or other physical properties of the web.

[0004] Thanks to their longer nips, the previously known shoe press devices provide a number of advantages in comparison to conventional roll presses, such as a higher dryness at the same nip pressure, or a pressing at a lower at nip pressure but with maintained dryness which is more gentle to the sheet

[0005] The patent publication US 4,917,768 discloses a previously known shoe press device in which the press shoe is supported via tubular sleeves rigidly affixed to and spaced apart on a support in a direction across the machine direction. Thereby, the sleeves are received in cylindrical recesses in the press shoe in order to allow the press shoe to move toward or from a counter roll and the nip pressure to be varied. The disclosed shoe press comprises hydraulic jacks upstream and downstream the sleeves for forcing the press shoe against the counter roll and for pivoting the shoe around an axis across the machine in order to vary the nip pressure in the machine direction. Thereby, the sleeves fit somewhat loosely in the recesses in the shoe, and a resilient seal encircles each sleeve for sealing the interface between the sleeve and the recess. Accordingly, the press shoe of the shoe press disclosed in US 4,917,768 is capable ofpivoting relative to the support for varying the nip pressure in the machine direction.

[0006] However, it has been found that such shoe presses can be associated with certain problems. Such a problem originates from the thermal expansion of the press shoe, which is a result of the heat generated by friction against the belt which runs over the press shoe and carries the paper or paperboard web through the press and by the hot hydraulic fluid which for different reasons is circulated through the shoe. The thermal expansion of the press shoe results in an elongation in the cross direction which creates bending tensions in the support and hydraulic arrangement of the press shoe, something which of course is undesired.

[0007] In EP 0 933 471, a shoe press is disclosed which reduces the problems originating from the thermal expansion of the press shoe, since it has the ability to tolerate relatively large elongations of the press shoe across the machine direction, and also other deformations of the press shoe. The disclosed shoe press comprises a press shoe extending in the cross-direction along the entire width of a web running through the press, and a plurality of articulated hydraulic loading cylinders supported by a support and spaced apart along the shoe. The loading cylinders define working chambers which are pressurizable by hydraulic fluid, so as to get the cylinders to urge the press shoe away from the support and toward a counter roll or other backing member for applying pressure to the web being carried through the nip defined between the shoe and the backing member. Each loading cylinder comprises a piston member disposed within a cylinder member. Either the piston or the cylinder comprises a two-part member having a first member relative the press shoe and a second member fixed relative to the support, while the remaining piston or cylinder comprises a coupler.

[0008] In a preferred embodiment of the shoe press according to EP 0 933 471, the two-part member consists of first and second cylinders, while the coupler comprises a piston which is slidably received in the two cylinders. In an alternative, also preferred embodiment the two-part member instead comprises first and second pistons, while the coupler comprises a cylinder which surrounds both pistons.

[0009] The coupler of the shoe press disclosed in EP 0 933 471 sealingly engages at least one of the members, so that the first member is urged away from the second member in a loading direction when pressurising the working chamber to cause the press shoe to be urged towards the backing member. In order to enable the loading cylinders to accommodate elongation of the press shoe across the machine direction, each coupler engages the respective first and second members at seals which enable the coupler to pivot relative the first and second members about axes parallel to the machine direction. Accordingly, the press shoe is free to expand thermally in the cross-machine direction without causing bending of any piston and/or cylinder members of the loading cylinders.

[0010] Since the press shoe of the shoe press disclosed in EP 0 933 471 also can move or pivot in the machine direction relative to the support, the shoe press comprises a stopping means which restricts the movement of the shoe forward in the machine direction.

[0011] In order to control the conditions in the nip of a shoe press, such as the pressure profile (curve) through the nip, it is usually desirable to be able to move to the press shoe forward or backwards in the machine direction in order to be able to influence the pressure profile through the nip so that the nip pressure is highest in the beginning and lower in the end of the nip, or vice versa. When performing such a regulation of the pressure profile through the nip, the press shoe, in principle, will follow an arc-shaped path with its centre in the central axis of the counter roll. This may result in a skewness in the machine direction between the parts included in the loading cylinders, i.e. between piston and cylinders or between pistons and cylinder. Such a skewness can generate forces both on the cylinder and on the shoe, which forces are directed in the machine direction or against the machine direction, depending on the direction of the skewness. If the skewness of the connecting member in a direction away from a possible stopping means (shoe support) is large enough, these forces may exceed the force directed towards the support, and resulting in instability. If the connecting member is tilted in a direction toward the shoe support, forces which are directed toward the shoe support are generated, something which increases the stresses on the shoe support.

[0012] Also in case a paper lump or the like unintentionally enters the nip, similar skewnesses can be generated and cause stresses on a shoe support.

Summary of the invention

[0013] Accordingly, the first object of the present invention is to provide a press device having an extended nip for pressing a running paper or paperboard web in which the press shoe unintentionally or intentionally can be tilted/pivoted around an imaginary axis across the machine direction with minimum skewness between the parts included in the loading cylinders, and without generating any excessively large forces directed towards a possible shoe support or the press shoe becoming unstable if the forces are directed against the machine direction (away from a possible shoe support).

[0014] In accordance with claim 1, this first object of the present invention is achieved by means of a press device comprising a press shoe aligned across the machine direction arranged for forming an extended nip in cooperation with a backing member for passage of the web during the pressing, a support which supports the press shoe in a movable way in a direction toward the backing member via aplurality of loading cylinders spaced apart along the press shoe for enabling application of pressure on the web during the pressing. Each of the loading cylinders comprises a first cylinder member having a first cylinder end which is attached to or integrated in the press shoe, and a second cylinder member having a second cylinder end which is attached to or integrated in the support, which first and second cylinder members are slidably connectedby a connecting member. The connecting member and the first cylinder member are movable in relation to each other with a first length of stroke, while the connecting member and the second cylinder member are movable in relation to each other with a second length of stroke, and the connecting member has a third length. Thereby, according to the invention, the first length of stroke is smaller than the second length of stroke, whereby the above-mentioned first object is achieved.

[0015] Further objects of the present invention will become apparent from the following description, while the features enabling the further objects to be achieved are defined in the dependent claims.

Brief description of the drawings

[0016] In the following, the invention will be described in greater detail with reference to the attached drawings, in which

Fig. 1A shows a schematic sectional view seen across the machine direction of a shoe press device with its press shoe in a first position, intended to generate a substantially symmetrical pressure curve through the nip,

Fig. 1B shows the shoe press device in Fig. 1A with its press shoe intentionally moved into a second position, intended to displace the pressure maximum of the pressure curve toward the end of the nip in comparison to when the press shoe is in the first position shown in Fig. 1A,

Fig. 2A shows a similar view as in Fig. 1A, but of a press device having an extended nip according to a preferred embodiment of the invention with its press shoe in a first position similar to the first position in Fig. 1A,

Fig. 2B shows the press device according to the invention in Fig. 2A, but now with its press shoe intentionally moved into a second position similar to the second position in Fig. 1B,

Fig. 3 schematically shows the motion pattern of the cylinder members and the coupling member belonging to a loading cylinder of a shoe press device when lengthening the loading cylinder with its first cylinder member tilted to a certain angle, and

Fig. 4 schematically shows the motion pattern of the cylinder members and the connecting member belonging to a loading cylinder of a press device according to the invention when lengthening the loading cylinder with the first cylinder member tilted to the same angle as in Fig.3.

Detailed description of preferred embodiments

[0017] For comparison, the attached figures 1A and 1B show two different schematic sectional views, seen across the machine direction MD, of a shoe press device which will be discussed further in the following description.

[0018] In Figs. 2A and 2B, similar views as in Fig. 1A and 1B are shown, but of a press device having an extended nip according to a preferred embodiment of the invention.

[0019] The press device according to the invention is intended for pressing a running paper or paperboard web, and comprises apress shoe 101 aligned across the machine direction MD and arranged for forming an extended nip 103 in cooperation with a backing member 102 for passage of the web 104 during the pressing.

[0020] The press device further comprises a support 105 which supports the press shoe in a, in direction toward the backing member, movable way via a plurality of loading cylinders 106 spaced apart along the press shoe 101 for enabling application of pressure on the web during the pressing.

[0021] Each of the above-mentioned loading cylinders 106 comprises a first cylinder member 107 having a first cylinder end 108 which is attached to or integrated in the press shoe 101, and a second cylinder member 109 having a second cylinder end 110 which is attached to or integrated in the support 105.

[0022] The expression "cylinder member", as used herein, should be understood as a functional part of the loading cylinder, which can be of a hydraulic or pneumatic type. Examples of such "cylinder members" comprise internally or externally substantially cylindrical sleeves which are open in at least one end, substantially cylindrical solid bodies or pistons, or substantially cylindrical recesses in the press shoe or in the support.

[0023] The first and second cylinder members 107, 109 are slidably connected by a connecting member 111, wherein the connecting member 111 and the first cylinder member 107 are movable in relation to each other with a first length of stroke L1, while the connecting member 111 and the second cylinder member 109 are movable in relation to each other with a second length of stroke L2, and the connecting member has a third length L3.

[0024] The expression "length of stroke", as used herein, should be understood as the maximum length of a cylinder member available for sliding displacement of a second, cooperating member in relation to said cylinder member.

[0025] According to the invention and in the preferred embodiment, the first length of stroke L1 is smaller than the second length of stroke L2.

[0026] In a particularly preferred embodiment of the press device according to the invention, the first length of stroke L1 is less than half of the second length of stroke L2.

[0027] In another advantageous embodiment, the third length L3 is larger than both the first L1 and the second L2 length of stroke, wherein the third length L3 particularly advantageously is larger than the first L1 and the second L2 length of stroke together.

[0028] In still another advantageous embodiment of the press device according to the invention, the connecting member 111 slidably connects the first 107 and the second 109 cylinder members in a sealed way by means of contacting seals 112, 113 in order to form at least one working chamber 114 within which the pressure of a pressurising medium, such as hydraulic oil or pressurised air, can be reduced in order to generate a shortening or increased in order to generate a lengthening of the loading cylinder 106. Thereby, the connection is arranged in such a way that a central axis C1 of the first cylinder member 107 and a central axis C3 of the connecting member 111 can be tilted to an angle in relation to each other and to a central axis C2 of the second 109 cylinder member during an intentional or unintentional tilting of the press shoe 101 during the pressing. In this embodiment, the first L1 and second L2 lengths of stroke, the third length L3, and the geometrical positions of the contacting seals 112,113 are adapted in order to minimise the angle A2 between the central axis C3 of the connecting member and the central axis C2 of the second cylinder member during the tilting.

[0029] Accordingly, the above-mentioned tilting either can be intentional or unintentional. The seals 112, 113 can advantageously be of the type disclosed in the above-discussed EP 0 933 471. As will become evident from the following description, also the connecting member can have different geometrical shapes.

[0030] In still another advantageous embodiment of the press device according to the invention, particularly illustrated in Fig. 2B, a shoe support 115 is fixated to the support for receiving forces in the machine direction MD exercised by the press shoe 101 in contact with the shoe support during the pressing. In this embodiment, one or several stopping means 116 are arranged on the first cylinder member 107 and/or on the connecting member 111, in order to restrict a maximum value of the first length of stroke L1, and thereby ensure a very low angle A2 between the central axes C3 and C2. In the press device illustrated in Figs. 2A and 2B, the stopping means 116 are constituted by a ring, screwed on the open end of the first cylinder member 107, and having a slightly smaller inside diameter than the diameter of the first cylinder member, wherein the ring 116 is intended to cooperate with the protruding seal 112 enclosing the connecting member 111. However, it is also conceivable with embodiments of the shoe press device according to the invention in which the stopping means has/have another suitable design. In connection with this embodiment, it should be noted that the shoe press device illustrated in Figs. 1A and B lacks stopping means for restricting the maximum value of its corresponding length of stroke 11.

[0031] In still another advantageous embodiment of the press device according to the invention, the first cylinder member 107 comprises an open third cylinder end 116 opposite the above-mentioned first cylinder end 108, while the second cylinder member 109 comprises an open fourth cylinder end 117 opposite the above-mentioned second cylinder end 110. In this embodiment, the third 116 and fourth cylinder ends 117 encircle a respective end of the connecting member 111 in order to form the working chamber 114 or several working chambers. Thereby, the connecting member 111 advantageously can be a substantially cylindrical sleeve, the interior of which constituting a part of the working chamber 114, as illustrated in Figs. 2A and 2B. In an alternative embodiment (not shown in the drawings), the connecting member instead is constituted of a solid, substantially cylindrical body, at each end of which a working chamber is formed, wherein one or several channels advantageously but not necessarily can be arranged between the two ends for pressure connection between the formed working chambers.

[0032] In still another alternative embodiment (not shown) of the shoe press device according to the invention, the first and second cylinder members are solid, substantially cylindrical bodies one end of which being enclosed by the connecting member in order to form the working chamber. Thereby, the sealing means should be arranged on the connecting member in order to make it possible to minimise its tilting/skewness in accordance with the invention.

[0033] It is particularly advantageous with embodiments of the invention in which the backing member 102 is a rotatable counter roll, and where a flexible belt 118 is arranged in an endless loop for running between the press shoe 101 and the paper or paperboard web 104 during the pressing. Thereby, the flexible belt preferably has the shape of a sleeve.

[0034] The press device having an extended nip according to the invention preferably is intended for wet-pressing, or for calendering a paper or paperboard web.

[0035] In the following, some of the advantages which can be achieved by means of the present invention will be illustrated through an example.

[0036] Fig. 1A shows a shoe press device with its press shoe in a first position, intended to generate a substantially symmetrical pressure curve through the nip.

[0037] Fig. 1B shows the shoe press device in Fig. 1A, but now with its press shoe intentionally moved into a second position, which is intended to displace the pressure maximum of the pressure curve towards the end of the nip in comparison to when the press shoe is in the first position shown in Fig. 1A. As is evident from Figs. 1A and 1B, the first length of stroke 11 of the illustrated shoe press device is larger than the second length of stroke 12.

[0038] Accordingly, the intentional displacement of the press shoe 1 into the second position shown in Fig. 1B is intended to displace the pressure maximum of the pressure curve towards the end of the nip, wherein the press shoe 1 and, consequently, the central axis c1 of the therewith associated first cylinder member 7 will be tilted forwards in the machine direction MD to an angle a1 in relation to the central axis c2 of the second cylinder member 9. In connection with this, it should be noted that the angles shown in the drawings, for reasons of clarity, have been exaggerated.

[0039] A large tilting of the connecting member (piston) 11 in direction towards the shoe support 15 results in the shoe support 15 being subj ected to large stresses during the pressing, since a force component is generated which will press against the first cylinder member 7 and, together with other forces directed forwards in the machine direction MD, will press the press shoe 1 against the shoe support 15.

[0040] Figs. 2A and 2B instead illustrate a press device having an extended nip according to a preferred embodiment of the invention. Fig. 2A shows the press device with its press shoe in a first position similar to the first position in Fig. 1A, while Fig. 2B shows the press device with its press shoe intentionally moved into a second position similar to the second position in Fig. 1B.

[0041] In Fig. 2B, the press shoe 101 has been intentionally tilted approximately as much as the press shoe 1 in Fig. 1B in order to make it possible to obtain a higher nip pressure in the end of the nip than in its beginning. Accordingly, the angle A1 between the central axis C1 of the first cylinder member 107 and the central axis C2 of the second cylinder member 109 is approximately as large as the angle a1 in Fig. 1B. As a result of the different parts of the loading cylinder 106 being arranged in accordance with the invention, the angle A2 between the central axis C3 of the connecting member 111 and the central axis C2 of the second cylinder member 109 now becomes significantly smaller than the corresponding angle a2 between the central axes c2 and c3 in Fig. 1B. Starting from the examples above, it should be evident to the skilled person that the minimization, i.e. reduction or even elimination, of the angle A2 which is achieved by means of the present invention reduces or even eliminates the force components in the machine direction MD, originating from pressurisation of the working chamber 114, which are exercised by the press shoe 101 on the shoe support 118.

[0042] Fig. 3 schematically shows the motion pattern of the cylinder members 7', 9' and the connecting member 11' belonging to a loading cylinder 6' of a shoe press device when lengthening the loading cylinder with its first cylinder member tilted to a certain angle.

[0043] In contrast, Fig. 4 schematically shows the motion pattern of the cylinder members 107', 109' and the connecting member 111' belonging to a loading cylinder 106' of a press device according to the invention when lengthening the loading cylinder with the first cylinder member tilted to the same angle as in Fig. 3.

[0044] As is evident from Fig.4, the press device according to the present invention enables the connecting member 111' to move substantially linearly and in parallel to the lengthening direction of the loading cylinder 106, when lengthening (or shortening) the loading cylinder 106'. This minimises the stresses on a possible shoe support.

[0045] During the lengthening (or shortening) of a loading cylinder 6' of the shoe press device shown in Fig. 3, the connecting member 11' instead will be tilted with different angles in relation to the lengthening direction of the loading cylinder 6' depending on how far the lengthening or shortening course has proceeded. This can generate very large stresses on a possible shoe support, or result in the press shoe becoming unstable in case the forces are directed towards the machine direction (backward in the machine direction). Furthermore, the frictional force between the press shoe and the shoe support will vary in a direction across the machine direction, depending on the larger deflection of the support (beam) in the middle (and resulting larger skewness of the piston). This can cause cross-machine variations in the machine-directional pressure curve of the shoe press.

[0046] The present invention should by no means be regarded as being limited to what has been described in the foregoing in connection with the different embodiments, or to what is shown in the attached drawings, but the scope of the invention is defined by the following claims.

[0047] The mechanical andhydraulic, alternatively pneumatic, components which are in included in the shoe press device according to the invention have not been described in any greater detail herein, since such components should be well-known to the skilled person and also are disclosed and discussed in the above-mentioned EP 0 933 471.

[0048] Furthermore, it should be noted that the paper web 104 preferably is carried through the nip 103 by one or several water receiving machine clothings, such as one or several press felts.

Claims

1. A press device having an extended nip for pressing a running paper or paperboard web, comprising a press shoe (101) aligned across the machine direction (MD) arranged for forming an extended nip (103) in cooperation with a backing member (102) for passage of said web (104) during the pressing, a support (105) which supports the press shoe in a movable way in a direction toward the backing member via a plurality of loading cylinders (106) spaced apart along the press shoe (101) for enabling application of pressure on the web during the pressing, wherein each of said loading cylinders (106) comprises a first cylinder member (107) having a first cylinder end (108) which is attached to or integrated in the press shoe (101), and a second cylinder member (109) having a second cylinder end (110) which is attached to or integrated in the support (105), which first and second cylinder members (107, 109) are slidably connected by a connecting member (111), wherein the connecting member (111) and the first cylinder member (107) are movable in relation to each other with a first length of stroke (L1), while the coupling member (111) and the second cylinder member (109) are movable in relation to each other with a second length of stroke (L2), and the connecting member has a third length (L3), characterised in that the first length of stroke (L1) is smaller than the second length of stroke (L2).

2. A press device having an extended nip according to claim 1, characterised in that the first length of stroke (L1) is less than half of the second length of stroke (L2).

3. A press device having an extended nip according to claim 1 or 2, characterised in that the third length (L3) is larger than both the first (L1) and the second (L2) length of stroke.

4. A press device having an extended nip according to any one of the preceding claims, characterised in that the third length (L3) is larger than the first (L1) and the second (L2) length of stroke together.

5. A press device having an extended nip according to any one of the preceding claims, wherein the connecting member (111) slidably connects the first (107) and the second (109) cylinder members in a sealed way by means of contacting seals (112, 113) in order to form at least one working chamber (114) within which the pressure of a pressurizing medium can be reduced in order to generate a shortening or increased in order to generate a lengthening of the loading cylinder (106), and in such a way that a central axis (C1) of the first cylinder member (107) and a central axis (C3) of the connecting member (111) can be tilted to an angle in relation to each other and to a central axis (C2) of the second (109) cylinder member during an intentional or unintentional tilting of the press shoe (101) during the pressing, characterised in that the first (L1) and second (L2) lengths of strokes, the third length (L3), and the geometrical positions of the contacting seals (112, 113) are adapted in order to minimise the angle (A2) between the central axis (C3) of the connecting member and the central axis (C2) of the second cylinder member during said tilting.

6. A press device having an extended nip according to any one of the preceding claims, wherein a shoe support (115) is fixated to the support for receiving forces in the machine direction (MD) exercised by the press shoe (101) in contact with the shoe support during the pressing, characterised in that one or several stopping means (116) are arranged on the first cylinder member (107) and/or on the connecting member (111) in order to restrict a maximum value of the first length of stroke (L1).

7. A press device having an extended nip according to claim 5 or 6, characterised in that the first cylinder member (107) comprises an open third cylinder end (116) opposite said first cylinder end (108) and the second cylinder member (109) comprises an open fourth cylinder end (117) opposite said second cylinder end (110), wherein the third (116) and fourth cylinder ends (117) enclose a respective end of said connecting member (111) in order to form the working chamber (114) or several working chambers.

8. A press device having an extended nip according to claim 7, characterised in that the connecting member (111) is a substantially cylindrical sleeve, the interior of which constituting a portion of the working chamber (114).

9. A press device having an extended nip according to claim 7, characterised in that the connecting member is a solid, substantially cylindrical body at both ends of which a working chamber is formed.

10. A press device having an extended nip according to claim 9, characterised in that the cylindrical body comprises one or several channels between the two ends for pressure connection between the working chambers.

11. A press device having an extended nip according to claim 5 or 6, characterised in that the first and second cylinder members are solid, substantially cylindrical bodies one end of which being enclosed by the connecting member in order to form the working chamber, wherein said sealing means are arranged on said connecting member.

12. A press device having an extended nip according to any one of the preceding claims, characterised in that the backing member (102) is a rotatable counter roll, wherein a flexible belt (118), preferably in the form of a sleeve, is arranged in an endless loop for running between the press shoe (101) and the paper or paperboard web (104) during the pressing.

13. Use of a press device having an extended nip according to any one of claims 1 to 12 for wet-pressing of a paper or paperboard web.

14. Use of a press device having an extended nip according to any one of claims 1 to 12 for calendering of a paper or paperboard web.

Ansprüche

1. Pressvorrichtung mit einer verlängerten Presszone zum Pressen einer laufenden Papier- oder Kartonbahn, die einen quer zur Maschinenrichtung (MD) ausgerichteten Pressschuh (101) zur Bildung einer verlängerten Presszone (103) im Zusammenspiel mit einem Gegenelement (102) zum Durchzug der genannten Bahn (104) während des Pressens, eine Stütze (105), die den Pressschuh in einem in einer Richtung zum Gegenelement beweglichen Zustand mittels einer Mehrzahl von Belastungszylindern (106) trägt, die einzeln entlang des Pressschuhes (101) verteilt sind, um Druckausübung auf die Bahn während des Pressens zu ermöglichen, wobei jeder der Belastungszylinder (106) ein erstes Zylinderelement (107), das ein erstes Zylinderende (108) hat, das am Pressschuh (101) befestigt oder im Pressschuh (101) integriert ist, und ein zweites Zylinderelement (109), das ein zweites Zylinderende (110) hat, das an der Stütze (105) befestigt oder in der Stütze (105) integriert ist, umfasst, wobei erstes und zweites Zylinderelement (107, 109) gleitbar durch ein Verbindungselement (111) verbunden sind, wobei das Verbindungselement (111) und das erste Zylinderelement (107) beweglich in Beziehung zueinander mit einer ersten Hublänge (L1) sind, während das Anschlusselement (111) und das zweite Zylinderelement (109) beweglich in Bezug zueinander mit einer zweiten Hublänge (L2) sind, und das Verbindungselement eine dritte Länge (L3) hat, umfasst, dadurch gekennzeichnet, dass die erste Hublänge (L1) kleiner als die zweite Hublänge (L2) ist.

2. Pressvorrichtung mit einer verlängerten Presszone nach Anspruch 1, dadurch gekennzeichnet, dass die erste Hublänge (L1) kleiner als die Hälfte der zweiten Hublänge (L2) ist.

3. Pressvorrichtung mit einer verlängerten Presszone nach Anspruch 1 oder 2, dadurch gekennzeichnet, dass die dritte Länge (L3) größer als sowohl die erste (L1) als auch die zweite (L2) Hublänge ist.

4. Pressvorrichtung mit einer verlängerten Presszone nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass die dritte Länge (L3) größer als die erste (L1) und die zweite (L2) Hublänge zusammen ist.

5. Pressvorrichtung mit einer verlängerten Presszone nach einem der vorhergehenden Ansprüche, wobei das Verbindungselement (111) das erste (107) und das zweite (109) Zylinderelement gleitbar in einem abgedichteten Zustand mittels Kontaktdichtungen (112, 113) verbindet, um mindestens eine Arbeitskammer (114) zu bilden, in der der Druck eines druckfesten Mediums verringert werden kann, um eine Stauchung des Belastungszylinders (106) zu erzeugen, oder in der der Druck eines druckfesten Mediums vergrößert werden kann, um eine Dehnung des Belastungszylinders (106) zu erzeugen, und solchermaßen verbindet, dass eine Mittelachse (C1) des ersten Zylinderelementes (107) und eine Mittelachse (C3) des Verbindungselementes (111) um einen Winkel in Beziehung zueinander und zu einer Mittelachse (C2) des zweiten (109) Zylinderelementes während eines absichtlichen oder unabsichtlichen Kippens des Pressschuhes (101) während des Pressens gekippt werden können, dadurch gekennzeichnet, dass die erste (L1) und die zweite (L2) Hublänge, die dritte Länge (L3) und die geometrischen Positionen der Kontaktdichtungen (112, 113) angepasst sind, um den Winkel (A2) zwischen der Mittelachse (C3) des Verbindungselementes und der Mittelachse (C2) des zweiten Zylinderelementes während des Kippens zu minimieren.

6. Pressvorrichtung mit einer verlängerten Presszone nach einem der vorhergehenden Ansprüche, wobei eine Schuhstütze (115) an der Stütze befestigt ist, um Kräfte in der Maschinenrichtung (MD) aufzunehmen, die durch den Pressschuh (101) bei Berührung mit der Schuhstütze während des Pressens ausgeübt werden, dadurch gekennzeichnet, dass ein oder mehrere Haltemittel (116) auf dem ersten Zylinderelement (107) und/oder auf dem Verbindungselement (111) angeordnet sind, um einen maximalen Wert der ersten Hublänge (L1) abzugrenzen.

7. Pressvorrichtung mit einer verlängerten Presszone nach Anspruch 5 oder 6, dadurch gekennzeichnet, dass das erste Zylinderelement (107) ein offenes drittes Zylinderende (116) dem ersten Zylinderende (108) gegenüberliegend umfasst und das zweite Zylinderelement (109) ein offenes viertes Zylinderende (117) dem zweiten Zylinderende (110) gegenüberliegend umfasst, wobei das dritte (116) und vierte Zylinderende (117) ein betreffendes Ende des Verbindungselementes (111) umschließt, um die Arbeitskammer (114) oder mehrere Arbeitskammern zu bilden.

8. Pressvorrichtung mit einer verlängerten Presszone nach Anspruch 7, dadurch gekennzeichnet, dass das Verbindungselement (111) eine im Wesentlichen zylindrische Hülse ist, deren Inneres einen Anteil der Arbeitskammer (114) ausmacht.

9. Pressvorrichtung mit einer verlängerten Presszone nach Anspruch 7, dadurch gekennzeichnet, dass das Verbindungselement ein stabiler, im Wesentlichen zylindrischer Körper ist, an dessen beiden Enden eine Arbeitskammer gebildet ist.

10. Pressvorrichtung mit einer verlängerten Presszone nach Anspruch 9, dadurch gekennzeichnet, dass der zylindrische Körper einen Kanal oder mehrere Kanäle zwischen den beiden Enden zur Druckverbindung zwischen den Arbeitskammern umfasst.

11. Pressvorrichtung mit einer verlängerten Presszone nach Anspruch 5 oder 6, dadurch gekennzeichnet, dass das erste und das zweite Zylinderelement stabile, im Wesentlichen zylindrische Körper, deren eines Ende durch das Verbindungselement umschlossen wird, um die Arbeitskammer zu bilden, wobei die Dichtungsmittel auf dem Verbindungselement angeordnet sind.

12. Pressvorrichtung mit einer verlängerten Presszone nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, dass das Gegenelement (102) eine drehbare Gegenwalze ist, wobei ein flexibles Band (118), vorzugsweise in der Form einer Hülse, in einer Endlosschleife angeordnet ist, um zwischen dem Pressschuh (101) und der Papier- oder Kartonbahn (104) während des Pressens zu laufen.

13. Verwendung einer Pressvorrichtung mit einer verlängerten Presszone nach einem der Ansprüche 1 bis 12 zum Nasspressen einer Papier- oder Kartonbahn.

14. Verwendung einer Pressvorrichtung mit einer verlängerten Presszone nach einem der Ansprüche 1 bis 12 zum Kalandrieren einer Papier- oder Kartonbahn.

Revendications

1. Presse à pince pour presser une bande de papier ou de carton en mouvement, comprenant un sabot presseur (101) aligné transversalement à la direction machine (SM) conçu pour former une pince (103) allongée en coopération avec un élément antagoniste (102) pour le passage de ladite bande (104) pendant le pressage, un support (105) qui supporte le sabot presseur d'une manière mobile en direction de l'élément antagoniste par l'intermédiaire d'une pluralité de cylindres de charge (106) espacés le long du sabot presseur (101) pour permettre l'application d'une pression sur la bande pendant le pressage, dans laquelle chacun des cylindres de charge (106) comprend un premier élément formant cylindre (107) ayant une première extrémité de cylindre (108) qui est fixée sur le sabot presseur (101) ou intégrée à celui-ci, et un deuxième élément formant cylindre (109) ayant une deuxième extrémité de cylindre (110) qui est fixée sur le support (105) ou intégrée à celui-ci, lesdits premier et deuxième éléments formant cylindre (107, 109) sont raccordés de manière coulissante par un élément de raccordement (111), dans laquelle l'élément de raccordement (111) et le premier élément formant cylindre (107) peuvent être déplacés l'un par rapport à l'autre sur une première longueur de course (L1), alors que l'élément de raccordement (111) et le deuxième élément formant cylindre (109) peuvent être déplacés l'un par rapport à l'autre sur une deuxième longueur de course (L2), et l'élément de raccordement a une troisième longueur (L3), caractérisée en ce que la première longueur de course (L1) est inférieure à la deuxième longueur de course (L2).

2. Presse à pince selon la revendication 1, caractérisée en ce que la première longueur de course (L1) est inférieure à la moitié à la deuxième longueur de course (L2).

3. Presse à pince selon la revendication 1 ou 2, caractérisée en ce que la troisième longueur (L3) est supérieure à la fois à la première (L1) et à la deuxième (L2) longueurs de course.

4. Presse à pince selon l'une quelconque des revendications précédentes, caractérisée en ce que la troisième longueur (L3) est supérieure à la première (L1) et à la deuxième (L2) longueurs de course réunies.

5. Presse à pince selon l'une quelconque des revendications précédentes, dans laquelle l'élément de raccordement (111) relie de manière coulissante le premier (107) et le deuxième (109) éléments formant cylindre de manière hermétique au moyen de joints d'étanchéité par contact (112, 113) afin de former au moins une chambre de travail (114) au sein de laquelle la pression d'un milieu de mise sous pression peut être réduite afin de produire un raccourcissement, ou accrue afin de produire un allongement du cylindre de charge (106), et de telle manière qu'un axe central (C1) du premier élément formant cylindre (107) et un axe central (C3) de l'élément de raccordement (111) puissent être inclinés d'un certain angle l'un par rapport à l'autre et par rapport à un axe central (C2) du deuxième élément formant cylindre (109) pendant une inclinaison intentionnelle ou non intentionnelle du sabot presseur (101) pendant le pressage, caractérisée en ce que la première (L1) et la deuxième (L2) longueurs de course, la troisième longueur (L3) et les positions géométriques des joints d'étanchéité par contact (112, 113) sont adaptées de façon à réduire au minimum l'angle (A2) entre l'axe central (C3) de l'élément de raccordement et l'axe central (C2) du deuxième élément formant cylindre pendant ladite inclinaison.

6. Presse à pince selon l'une quelconque des revendications précédentes, dans laquelle un support de sabot (115) est fixé sur le support pour recevoir des forces dans la direction machine (SM) exercées par le sabot presseur (101) en contact avec le support de sabot pendant le pressage, caractérisée en ce qu'un ou plusieurs moyens d'arrêt (116) sont disposés sur le premier élément formant cylindre (107) et/ou sur l'élément de raccordement (111) afin de limiter une valeur maximale de la première longueur de course (L1).

7. Presse à pince selon la revendication 5 ou 6, caractérisée en ce que le premier élément formant cylindre (107) comprend une troisième extrémité ouverte de cylindre (116) opposée à ladite première extrémité de cylindre (108) et le deuxième élément formant cylindre (109) comprend une quatrième extrémité ouverte de cylindre (117) opposée à ladite deuxième extrémité de cylindre (110), dans laquelle la troisième (116) et la quatrième (117) extrémités de cylindre entourent une extrémité respective dudit élément de raccordement (111) afin de former la chambre de travail (114) ou plusieurs chambres de travail.

8. Presse à pince selon la revendication 7, caractérisée en ce que l'élément de raccordement (111) est un manchon sensiblement cylindrique, dont l'intérieur constitue une portion de la chambre de travail (114).

9. Presse à pince selon la revendication 7, caractérisée en ce que l'élément de raccordement est un corps plein sensiblement cylindrique, aux deux extrémités duquel une chambre de travail est formée.

10. Presse à pince selon la revendication 9, caractérisée en ce que le corps cylindrique comprend un ou plusieurs canaux entre les deux extrémités pour assurer une connexion en pression entre les chambres de travail.

11. Presse à pince selon la revendication 5 ou 6, caractérisée en ce que les premier et deuxième éléments formant cylindre sont des corps pleins sensiblement cylindriques dont une extrémité est entourée par l'élément de raccordement afin de former la chambre de travail, dans laquelle lesdits moyens d'étanchéité sont disposés sur ledit élément de raccordement.

12. Presse à pince selon l'une quelconque des revendications précédentes, caractérisée en ce que l'élément antagoniste (102) est un contre-rouleau rotatif, dans laquelle une courroie souple (118), de préférence sous la forme d'un manchon, est disposée en une boucle sans fin de façon à passer entre le sabot presseur (101) et la bande (104) de papier ou de carton pendant le pressage.

13. Utilisation d'une presse à pince selon l'une quelconque des revendications 1 à 12 pour le pressage humide d'une bande de papier ou de carton.

14. Utilisation d'une presse à pince selon l'une quelconque des revendications 1 à 12 pour le calandrage d'une bande de papier ou de carton.

Drawing