JP4838473B2 - Press device with extended press nip for squeezing a moving paperboard web - Google Patents

Abstract

A press device having an extended nip comprising a press shoe (101) aligned across the machine direction (MD) and a support (105) which supports the press shoe via a plurality of loading cylinders (106) along the press shoe (101) in order to enable application of pressure on the web during the pressing. The loading cylinders (106) comprise a first cylinder member (107) attached to or integrated in the press shoe (101), and a second cylinder member (109) attached to or integrated in the support (105). The 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). Thereby, the first length of stroke (L1) is smaller than the second length (L2) of stroke. The shoe press device can particularly advantageously be utilised for wet-pressing or calendering of paper or paperboard webs.

Description

[0001]
(Technical field)
The present invention relates to a pressing device having an extended nip intended to squeeze a running paper or paperboard web. More particularly, the present invention provides a support for supporting a press shoe adjacent to a counter roll or another backing member such that the press shoe and the backing member form an extended nip therebetween. And further relates to a shoe press of the type including a hydraulic or pneumatic device for pressing the press shoe against the backing member to apply pressure on the web passing through the nip.
[0002]
The pressing device according to the invention can be used advantageously not only for wet pressing wet paper or paperboard webs, but also for calendering or other finishing of dry paper or paperboard. Moreover, the press apparatus by this invention can also be utilized for fiber webs other than paper and paperboard.
[0003]
(Background of the Invention)
For a long time, shoe presses, ie presses with extended nips, when producing various grades of paper and paperboard, mainly for wet pressing, with the purpose of increasing web dryness, and the surface properties of the web Or have been used to perform calendering and other finishes to improve other physical properties.
[0004]
Thanks to these longer nips, known shoe presses have a higher dryness at the same nip pressure, or a softer dryness to the sheet is maintained even when squeezed at a lower nip pressure. It offers several advantages over conventional roll press machines.
[0005]
U.S. Pat. No. 4,917,768 discloses a known shoe press apparatus in which a press shoe is supported through a cylindrical sleeve, the cylindrical sleeve being rigidly fixed to the support in a direction transverse to the machine direction. ing. This allows the sleeve to be received in the cylindrical recess of the press shoe to allow the press shoe to move away from or away from the counter roll and the nip pressure to change. The disclosed shoe press machine is provided upstream of the sleeve to press the press shoe against the counter roll and to pivot the shoe about an axis across the machine for the purpose of changing the nip pressure in the machine direction. And a hydraulic jack at the downstream. This allows the sleeves to fit somewhat loosely in the recesses in the shoe, and a resilient seal surrounds each sleeve to seal the interface between the sleeve and the recess. Thus, the press shoe of the shoe press disclosed in US Pat. No. 4,917,768 can pivot with respect to the support to change the nip pressure in the machine direction.
[0006]
However, it has been found that such shoe presses can be associated with several problems. These problems are due to the thermal expansion of the press shoe, which can be caused by friction on the belt that runs over the press shoe and carries the paper or paperboard web through the press machine, and can vary. The heat generated by the hot hydraulic fluid circulating through the shoe for a reason. The thermal expansion of the press shoe results in a transverse stretch that generates bending tension in the press shoe support hydraulic device, which of course is rather undesirable.
[0007]
EP 0 933 471 has the ability to allow a relatively large extension of the press shoe in the direction transverse to the machine direction, and also other deformations of the press shoe, so that the thermal expansion of the press shoe is avoided. A shoe press machine is disclosed that reduces the resulting problems. The disclosed shoe press includes a press shoe extending transversely along the entire length of the web passing through the press and a plurality of articulated hydraulic loads supported by a support and spaced apart along the shoe. Including cylinders. The load cylinder is a counter roll or another backing member that separates the press shoe from the support to apply pressure to the web being conveyed through the nip defined between the shoe and the backing member. A working chamber is defined that can be pressurized by the hydraulic fluid so as to press against. Each loading cylinder includes a piston member disposed within the cylinder member. Either the piston or cylinder includes a two-part member having a first member fixed to the press shoe and a second member fixed to the support, while the remaining piston or cylinder has a coupler. Including.
[0008]
In a preferred embodiment of the shoe press according to EP 0 933 471, the two-part member consists of a first cylinder and a second cylinder, but the coupler includes a piston slidably received in the two cylinders. . In an alternative and preferred embodiment, the two-part member, unlike this, includes a first piston and a second piston, whereas the coupler includes a cylinder surrounding both pistons.
[0009]
In the shoe press machine coupler disclosed in European Patent No. 0933471, when pressurizing the working chamber and pressing the press shoe against the backing member, the first member is separated from the second member in the load direction. In a sealing engagement with at least one of the members. Each coupler is pivoted with respect to the first and second members about an axis parallel to the machine direction so as to allow the load cylinder to accommodate the extension of the press shoe across the machine direction. Engaging the first and second members, respectively. Therefore, the press shoe can be freely thermally expanded in the cross machine direction and does not cause any bending of any piston and / or cylinder member of the load cylinder.
[0010]
Since the press shoe of the shoe press disclosed in EP 0933471 can move or pivot in the machine direction relative to the support, the shoe press limits the forward movement of the shoe in the machine direction Including a stop member.
[0011]
To control the state at the nip of the shoe press, such as the pressure profile (curve) through the nip, the press shoe can be moved back and forth in the machine direction so that the nip pressure is at the beginning of the nip. It is often desirable to apply a pressure profile through the nip so that it is highest and lower toward the edge, or vice versa. When performing such adjustment of the pressure profile through the nip, the press shoe will follow an arcuate line of movement centered about the central axis of the counter roll. This can result in machine direction distortions between the parts contained in the load cylinder, i.e. between the piston and the cylinders or between the pistons and the cylinders. Such distortions can generate forces on both the cylinder and the shoe, and these forces are directed in the machine direction or the reverse machine direction, depending on the direction of the distortion. If the distortion of the connecting member in the direction away from the possible stop means (shoe support) is sufficiently large, these forces can exceed the force towards the support and consequently become unstable. . When the connecting member tilts in the direction toward the shoe support, a force is generated toward the shoe support, which increases the stress on the shoe support somewhat.
[0012]
Even when a block of paper or the like unexpectedly enters the nip, the same distortion may occur and cause stress on the shoe support.
[0013]
(Summary of Invention)
SUMMARY OF THE INVENTION Accordingly, a first object of the present invention is a pressing device having an extended nip for squeezing a running paper or paperboard web, wherein the press shoe unexpectedly or intentionally crosses the machine direction. Can be tilted / swiveled around, with minimal distortion between parts contained in the load cylinder, and unstable when the force is directed in the direction of the machine (away from possible shoe support) It is to provide a pressing device that does not generate any excessive force towards the possible shoe support or press shoe.
[0014]
According to claim 1, this first object of the invention is in a direction transverse to the machine direction, arranged to form an extended nip that cooperates with a backing member for the web to pass during squeezing. Supports the press shoe movably toward the backing member through a facing press shoe and multiple load cylinders spaced along the press shoe to allow pressure to be applied to the web during squeezing Achieved by a pressing device. Each load cylinder includes a first cylinder member having a first cylinder end attached to or integrated with the press shoe, and a second cylinder member having a second cylinder end attached to or integrated with the support. The first and second cylinder members are slidably connected by a connecting member. The connecting member and the first cylinder member are movable relative to each other with a first stroke length, but the connecting member and the second cylinder member are movable relative to each other with a second stroke length, and the connecting member has a third length. Have. Thus, according to the present invention, the first stroke length is shorter than the second stroke length, thereby achieving the first object described above.
[0015]
Further objects of the present invention will become apparent from the following description, but the features that make it possible to achieve further objects are defined in the dependent claims.
[0016]
The present invention will now be described in more detail with reference to the accompanying drawings.
[0017]
Detailed Description of Preferred Embodiments
For comparison, the accompanying FIGS. 1A and 1B show two different schematic cross-sectional views as viewed across the machine direction MD of the shoe press apparatus discussed further below.
[0018]
2A and 2B are similar to FIGS. 1A and 1B, but are views of a press apparatus having an extended nip according to a preferred embodiment of the present invention.
[0019]
The pressing device according to the present invention includes a press shoe 101 for the purpose of squeezing a running paper or paperboard web, the press shoe being aligned in a direction transverse to the machine direction MD, and the web 104 during squeezing. In order to form an expansion nip 103 in cooperation with the backing member 102 for passing the
[0020]
The pressing device can be moved in a direction toward the backing member via a plurality of load cylinders 106 spaced along the press shoe 101 to allow pressure to be applied to the web during squeezing. A support 105 for supporting the press shoe is further included.
[0021]
Each load cylinder 106 includes a first cylinder member 107 having a first cylinder end 108 attached or integrated to the press shoe 101 and a second cylinder end 110 attached or integrated to a support 105. And a second cylinder member 109 having
[0022]
The expression “cylinder member” as used herein is to be understood as a functional part of a load cylinder which can be of hydraulic or pneumatic type. Examples of such “cylinder members” include a generally cylindrical sleeve open or open at least at one end, a substantially cylindrical solid object or piston, or a substantially cylindrical cylinder in a press shoe or support. There is a concave shape.
[0023]
The first and second cylinder members 107 and 109 are slidably connected to each other by a connecting member 111. The connecting member 111 and the first cylinder member 107 are movable relative to each other by a first stroke length L1. The second cylinder member 109 can move with respect to each other by a second stroke length L2, and the connecting member has a third length L3.
[0024]
The expression “stroke length” as used herein should be understood as the maximum length of the cylinder member that can be used for the sliding displacement of the second cooperating member relative to the cylinder member.
[0025]
According to the present invention and in a preferred embodiment, the first stroke length L1 is shorter than the second stroke length L2.
[0026]
In a particularly preferred embodiment of the pressing device according to the invention, the first stroke length L1 is less than half of the second stroke length L2.
[0027]
In another advantageous embodiment, the third length L3 is longer than both the first stroke length L1 and the second stroke length L2, and the third length L3 is the first stroke length L1 and the second stroke length L2. It is particularly advantageous to have a length longer than the combined.
[0028]
In a further advantageous embodiment of the pressing device according to the invention, the connecting member 111 is sealed with the first cylinder member 107 and the second cylinder by contact seals 112, 113 to form at least one working chamber 114. The member 109 can be slidably connected, and the pressure of a pressurized medium such as hydraulic oil or compressed air can be reduced inside the working chamber to shorten the load cylinder 106 and raised to extend it. This allows the central axis C1 of the first cylinder member 107 and the central axis C3 of the connecting member 111 to be connected to each other and to the central axis of the second cylinder member 109 during the intentional or unintentional inclination of the press shoe 101 during compression. It can be tilted at a certain angle with respect to C2. In this embodiment, the first stroke length L1, the second stroke length L2, the third length L3, and the geometrical positions of the contact seals 112, 113 are adjusted between the central axis C3 of the coupling member and the second Adapted to minimize the angle A2 between the central axis C2 of the cylinder member.
[0029]
Therefore, the above-mentioned inclination can be either intentional or unexpected. The seals 112, 113 can advantageously be of the type disclosed in the aforementioned European Patent No. 0933471. As will become apparent from the following description, the connecting members can also have various geometric shapes.
[0030]
In a further advantageous embodiment of the pressing device according to the invention, in particular shown in FIG. 2B, the shoe support 115 exerts a force in the machine direction MD applied by the press shoe 101 in contact with the shoe support during squeezing. Secured to a support for receiving. In this embodiment, one or several stop means 116 are arranged on the first cylinder member 107 and / or on the coupling member 111 in order to limit the maximum value of the first stroke length L1. Establishes a very small angle A2 between the central axes C3 and C2. In the press apparatus shown in FIGS. 2A and 2B, the stopping means 116 is constituted by a ring and is screwed onto the open end of the first cylinder member 107, and has an inner diameter slightly smaller than the diameter of the first cylinder member. The ring 116 is adapted to cooperate with the protruding seal 112 surrounding the connecting member 111. However, it is also possible to envisage embodiments of the shoe press device according to the invention in which the stop means have another suitable design. In connection with this embodiment, it should be noted that the shoe press apparatus shown in FIGS. 1A and 1B has no stopping means for limiting the maximum value of its corresponding stroke length l1.
[0031]
In yet another advantageous embodiment of the pressing device according to the invention, the first cylinder member 107 comprises an open third cylinder end 116 opposite to the first cylinder end 108 described above, but the second cylinder member 109. Includes an open fourth cylinder end 117 opposite to the second cylinder end 110 described above. In this embodiment, the third cylinder end 116 and the fourth cylinder end 117 surround each end of the connecting member 111 to form one or several working chambers 114. This advantageously allows the connecting member 111 to be a substantially cylindrical sleeve, the interior of which forms part of the working chamber 114 as shown in FIGS. 2A and 2B. In an alternative embodiment (not shown in the drawing), the connecting member instead consists of a solid, generally cylindrical object, at each end of which a working chamber is formed, with one or several channels. For pressure communication between the formed working chambers, it can be advantageously but not necessarily arranged between the two ends.
[0032]
In yet another alternative embodiment (not shown) of the shoe press device according to the invention, the first and second cylinder members are solid, substantially cylindrical objects, one end of which forms a working chamber. Is surrounded by a connecting member. Thereby the sealing means should be placed on the connecting member in order to minimize its tilt / distortion according to the present invention.
[0033]
The backing member 102 is a rotatable counter roll, and 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 squeezing. The embodiments of the present invention are particularly advantageous. Accordingly, it is preferable that the flexible belt has a sleeve shape.
[0034]
The pressing device with an extended nip according to the invention is preferably intended for wet pressing or calendering of paper or paperboard web.
[0035]
In the following, some of the advantages that can be achieved by the present invention are illustrated by examples.
[0036]
FIG. 1A shows a shoe press apparatus with a press shoe in a first position for generating a generally symmetrical pressure curve through the nip.
[0037]
FIG. 1B shows the shoe press apparatus of FIG. 1A, in which the maximum pressure of the pressure curve is displaced towards the end of the nip compared to when the press shoe is in the first position of FIG. 1A. In order to do this, the press shoe is intentionally moved to the second position. As apparent from FIGS. 1A and 1B, the first stroke length 11 of the illustrated shoe press apparatus is larger than the second stroke length 12.
[0038]
Therefore, the intentional displacement of the press shoe 1 to the second position shown in FIG. 1B is to displace the maximum pressure of the pressure curve towards the end of the nip and is related to the press shoe 1 and therefore to this. The central axis c1 of the first cylinder member 7 is inclined forward in the machine direction MD by an angle a1 with respect to the central axis c2 of the second cylinder member 9. In this regard, it should be noted that the angles shown in the figures are exaggerated for clarity.
[0039]
The large inclination of the connecting member (piston) 11 in the direction toward the shoe support 15 results in a force component that presses the first cylinder member 7, and supports the shoe together with other forces that move forward in the machine direction MD. Since the press shoe 1 is pressed against the object 15, the shoe support 15 receives a large stress during the squeezing.
[0040]
2A and 2B illustrate a press apparatus having an extended nip according to a preferred embodiment of the present invention. 2A shows the press device with the press shoe in a first position similar to the first position in FIG. 1A, while FIG. 2B is intended for the press shoe in a second position similar to the second position in FIG. 1B. FIG.
[0041]
In FIG. 2B, the press shoe 101 is intentionally tilted to approximately the same degree as the press shoe 1 in FIG. 1B so that the nip pressure can be higher at the end of the nip than its beginning. Therefore, 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 substantially the same as the angle a1 in FIG. 1B. As a result of the different parts of the load cylinder 106 being arranged according to the present 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 is now the central axis c2 in FIG. Considerably smaller than the corresponding angle a2 between c3 and c3. Starting from the above example, the minimization, ie, reduction or removal of the angle A2 achieved by the present invention is that of the machine direction MD resulting from the pressurization of the working chamber 114 performed by the press shoe 101 on the shoe support 118. It should be apparent to those skilled in the art to reduce or even remove the force component.
[0042]
FIG. 3 shows the movement pattern of the cylinder members 7 ′ and 9 ′ and the connecting member 11 ′ belonging to the load cylinder of the shoe press device when the first cylinder member is inclined by a certain angle and the load cylinder 6 ′ is extended. Shown schematically.
[0043]
In contrast, FIG. 4 shows that the first cylinder member is inclined at the same angle as in FIG. 3, and the cylinder members 107 ′, 109 ′ belonging to the load cylinder of the press device according to the invention when the load cylinder 106 ′ is extended. And the movement pattern of connecting member 111 'is shown schematically.
[0044]
As is apparent from FIG. 4, the press device according to the present invention moves the connecting member 111 ′ in a substantially linear and parallel manner in the extending direction of the load cylinder 106 when the load cylinder 106 ′ is extended (or shortened). Can do. This minimizes possible stress on the shoe support.
[0045]
While extending (or shortening) the load cylinder 6 ′ of the shoe press apparatus shown in FIG. 3, instead of the connecting member 11 ′, depending on how far the extension or shortening stroke proceeds, It can be tilted at various angles with respect to the extension direction. This can generate very large stresses on the possible shoe support, or the press shoe can become unstable if the force is directed in the machine direction (backward in the machine direction). Furthermore, the frictional force between the press shoe and the shoe support changes in the direction across the machine direction as a result of the greater bending of the support (beam) in the middle (resulting in a significant distortion of the piston). . This can cause cross machine fluctuations in the pressure curve in the machine direction of the shoe press.
[0046]
The present invention should not be construed as limited to what has been described herein with reference to various embodiments or is illustrated in the accompanying figures. The scope of the present invention is defined by the appended claims.
[0047]
The mechanical and hydraulic, alternatively pneumatic components included in the shoe press apparatus according to the present invention should be well known to those skilled in the art and are further described in the above-mentioned European Patent No. 0933471. As disclosed and discussed, it has not been described in detail herein.
[0048]
Furthermore, it should be noted that the paper web 104 is conveyed through the nip 103 by one or several water absorbent machine closings, such as one or several press felts.
[Brief description of the drawings]
FIG. 1A is a schematic cross-sectional view, taken across the machine direction of a shoe press apparatus, with a press shoe in a first position for the purpose of generating a substantially symmetrical pressure curve through the nip.
FIG. 1B shows that the press shoe is intentionally used to move the pressure maximum of the pressure curve toward the end of the nip as compared to the case where the press shoe is in the first position shown in FIG. 1A. FIG. 1B shows the shoe press device of FIG. 1A moved to a second position.
2A is a view similar to FIG. 1A, but with a press shoe having an extended nip according to a preferred embodiment of the present invention, wherein the press shoe is in a first position similar to the first position in FIG. 1A. .
2B is a press device according to the present invention in FIG. 2A, but the press shoe has been intentionally moved to a second position similar to the second position in FIG. 1B.
FIG. 3 is a diagram schematically showing a movement pattern of a cylinder member and a connecting member belonging to a load cylinder of a shoe press device when the first cylinder member is inclined at a certain angle to lengthen the load cylinder.
4 schematically shows a movement pattern of a cylinder member and a connecting member belonging to a load cylinder of a press device according to the present invention when the first cylinder member is inclined at the same angle as that in FIG. 3 to lengthen the load cylinder. FIG.

Claims (13)

  Forming an expansion nip (103) that cooperates with a backing member (102) through which the web (104) passes during squeezing in a press apparatus having an expansion nip for squeezing a running paper or paperboard web A press shoe (101) oriented in a direction transverse to the machine direction (MD), and a press shoe (101) to allow pressure to be applied to the web during squeezing A plurality of load cylinders (106) spaced along the support member (105) for supporting the press shoe movably toward the backing member, wherein each load cylinder (106) includes a press shoe (101). A first cylinder member (107) having a first cylinder end (108) attached or integrated to the support) and a first cylinder attached or integrated to the support (105). A second cylinder member (109) having a cylinder end (110), and the first and second cylinder members (107, 109) are slidably coupled by a coupling member (111). ) And the first cylinder member (107) are movable relative to each other by the first stroke length (L1), but the connecting member (111) and the second cylinder member (109) are movable relative to each other by the second stroke length (L2). An expansion nip that is movable and the connecting member has a third length (L3), wherein the first stroke length (L1) is shorter than the second stroke length (L2). Press machine.   The press device with an extended nip according to claim 1, characterized in that the first stroke length (L1) is less than half of the second stroke length (L2).   3. Press device with an extended nip according to claim 1 or 2, characterized in that the third length (L3) is greater than both the first stroke length (L1) and the second stroke length (L2). . The third length (L3) is larger than the sum of the first stroke length (L1) and the second stroke length (L2), according to any one of claims 1 to 3 . A pressing device having an extended nip. The connecting member (111) can slide the first cylinder member (107) and the second cylinder member (109) in a sealing manner by the contact seals (112, 113) to form at least one working chamber (114). In the working chamber, the pressure of the pressurized medium can be lowered to shorten the load cylinder (106) and raised to extend, thus the first cylinder member (107) The central shaft (C1) and the central shaft (C3) of the connecting member (111) are connected to each other and to the center of the second cylinder member (109) during the intentional or unintentional tilting of the press shoe (101) during pressing. with respect to the axis (C2), it can be tilted at an angle, a pressing device having an extended nip as claimed in any one of claims 4, first stroke length (L1 , The second stroke length (L2), the third length (L3), and the geometric position of the contact seals (112, 113) are determined between the central axis (C3) of the connecting member and the second cylinder during the inclination. Press device with an extended nip, characterized in that it is adapted to minimize the angle (A2) between the central axis (C2) of the member. Shoe supporting structure (115) is affixed to a support material for receiving the force of the shoe supporting structure and in contact with and press shoe (101) by the applied machine direction (MD) during pressing, claim 1 A pressing device having an extended nip according to any one of claims 1 to 5 , wherein one or several stop means (116) limit the maximum value of the first stroke length (L1). A pressing device with an extended nip, characterized in that it is arranged on the first cylinder member (107) and / or on the connecting member (111).   The first cylinder member (107) includes an open third cylinder end (116) opposite to the first cylinder end (108), and the second cylinder member (109) includes the second cylinder end ( 110) and an open fourth cylinder end (117) opposite the third cylinder end (116) and the fourth cylinder end (117) form one or several working chambers (114). 7. A pressing device with an extended nip according to claim 5 or 6, characterized in that each end of the connecting member (111) is enclosed to do so.   8. Press device with extended nip according to claim 7, characterized in that the connecting member (111) is a substantially cylindrical sleeve, the interior of which forms part of the working chamber (114).   8. The press apparatus having an extended nip according to claim 7, wherein the connecting member is a solid and substantially cylindrical object, and working chambers are formed at both ends thereof.   10. Press device with extended nip according to claim 9, characterized in that the cylindrical object comprises one or several channels between the two ends for pressure communication between the working chambers. A flexible belt (118) in which the backing member (102) is a rotatable roll, preferably in the form of a sleeve, is pressed with a press shoe (101) and a paper or paperboard web (104). 11. A press apparatus having an extended nip according to any one of claims 1 to 10 , characterized in that it is arranged in an endless loop manner for traveling between the two.   12. Press device with extended nip according to any one of claims 1 to 11, characterized in that it is intended for wet pressing of paper or paperboard webs.   12. Press device with extended nip according to any one of claims 1 to 11, characterized in that it is intended for calendering of paper or paperboard webs.

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