JP2003516482A - Press apparatus having an 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

Detailed Description of the Invention

FIELD OF THE INVENTION The present invention relates to a pressing device having an expanding nip intended to squeeze a running web of paper or paperboard. More particularly, the present invention provides a support for supporting a press shoe adjacent a counter roll or another backing member such that the press shoe and the backing member form an expansion nip therebetween. And further including a hydraulic or pneumatic device for pressing the press shoe against the backing member to exert pressure on the web passing through the nip.

[0002] The pressing device according to the invention can be used to particular advantage not only for wet pressing of webs of wet paper or paperboard, but also for calendering or other finishing of dried paper or paperboard. . The pressing device according to the invention can also be used for fiber webs other than paper and paperboard.

BACKGROUND OF THE INVENTION For a long time, shoe press devices, ie presses with extended nips, wet squeeze primarily for the purpose of increasing web dryness when producing various grades of paper and board. In order to improve the surface properties or other physical properties of the web, it has been used for calendering and other finishing.

Due to these longer nips, the known shoe press device either has a higher dryness at the same nip pressure, or maintains a softer dryness to the sheet when squeezed at a lower nip pressure. It offers several advantages over traditional roll presses, such as

US Pat. No. 4,917,768 discloses a known shoe pressing apparatus in which a press shoe is supported through a tubular sleeve, the tubular sleeve being rigidly fixed and spaced from a support transverse to the machine direction. Is disclosed. This allows the sleeve to be received within the cylindrical recess of the press shoe to allow the press shoe to move toward or away from the counter roll and the nip pressure to change. The disclosed shoe press machine uses an upstream sleeve to press the press shoe against a counter roll and to pivot the shoe about an axis that traverses the machine to change the nip pressure in the machine direction. And a downstream hydraulic jack. This causes the sleeves to fit somewhat loosely within the shoe recesses and a resilient seal surrounds each sleeve to seal the interface between the sleeves and the recesses. Thus, the press shoe of the shoe press disclosed in U.S. Pat. No. 4,917,768 can pivot relative to the support to change the nip pressure in the machine direction.

However, it has been found that such shoe presses can have some problems. Such problems are due to the thermal expansion of the press shoe, which is caused by friction on the belt that travels over the press shoe and carries the web of paper or paperboard through the press, as well as various causes. The heat generated by the hot hydraulic fluid circulating through the shoe for reasons. Thermal expansion of the press shoe results in transverse stretching which causes bending tension in the support hydraulics of the press shoe, which is, of course, highly undesirable.

EP 0933471 has the ability to allow a relatively large extension of the press shoe in a direction transverse to the machine direction, and also other deformations of the press shoe, so that Shoe presses are disclosed that reduce problems due to thermal expansion. The disclosed shoe press includes a press shoe extending transversely along the length of the web passing through the press and a plurality of articulated hydraulic loads supported by a support and spaced along the shoe. Including a cylinder.
A loading cylinder is a cylinder that separates the press shoe from a support to apply pressure to a web being conveyed through a nip defined between the shoe and the backing member, such as a counter roll or another backing member. Defines a working chamber that can be pressurized by the hydraulic fluid so as to be pressed against. Each loading cylinder includes a piston member located inside the cylinder member. Either the piston or the 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 comprises a coupler. Including.

In a preferred embodiment of the shoe press according to EP 0933471, the two-part member consists of a first cylinder and a second cylinder, but the coupler is slidably received in two cylinders. Including piston. In an alternative and preferred embodiment, the two-part member differs from this in that it comprises a first piston and a second piston, whereas the coupler comprises a cylinder surrounding both pistons.

The coupler of the shoe press disclosed in European Patent No. 0933471 is such that when the working chamber is pressed to press the press shoe toward the backing member, the first member and the second member are moved in the load direction. Sealingly engages at least one of the members so as to be spaced apart from. Each coupler is pivotable 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 stretching of the press shoe across the machine direction. In a seal that enables the first and second members, respectively. Thus, the press shoe is free to thermally expand in the cross machine direction and does not cause any bending of any piston and / or cylinder member of the loading cylinder.

The press shoe of the shoe pressing machine disclosed in EP 0933471 can be moved or swiveled in the machine direction relative to the support so that the shoe
The press includes stop members that limit the forward movement of the shoe in the machine direction.

To control the conditions in 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, which causes the nip pressure to increase. It is often desirable to exert a pressure profile through the nip such that it peaks at the beginning and goes down towards the end, or vice versa. When making such adjustments of the pressure profile through the nip, the press shoe will primarily follow an arcuate line of travel centered on the central axis of the counter roll. This may result in machine-direction distortion between the parts contained in the load cylinder, ie 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,
These forces are directed in the machine or reverse machine direction, depending on the direction of the distortion. If the deflection of the connecting member in the direction away from the possible stopping means (shoe support) is large enough, these forces may exceed the force towards the support, resulting in instability. . If the coupling member tilts in the direction towards the shoe support, a force towards the shoe support occurs, which increases the stress on the shoe support somewhat.

If a lump of paper or the like suddenly enters the nip, the same distortion may occur and cause stress on the shoe support.

SUMMARY OF THE INVENTION Accordingly, a first object of the present invention is a press device having an expanding nip for squeezing a running paper or paperboard web, wherein the press shoe is inadvertently or intentionally. , Can tilt / swirl around an imaginary axis transverse to the machine direction,
A possible shoe support or press shoe that has minimal distortion between the parts contained in the load cylinder and that becomes unstable when the forces are facing in the machine direction (away from the possible shoe support). It is an object of the present invention to provide a pressing device that does not generate excessive excessive force toward the pressing device.

According to claim 1, this first object of the invention is transverse to the machine direction, arranged to form an expanding nip cooperating with a backing member for the passage of a web during pressing. The press shoe oriented toward the direction of the press and a movable press towards the backing member through a plurality of load cylinders spaced along the press shoe to allow the web to be pressed during pressing. And a support that supports the shoe,
Achieved by pressing equipment. Each load cylinder includes a first cylinder member having a first cylinder end attached to or integrated with a press shoe and a second cylinder member having a second cylinder end attached to or integrated with a support, The first and second cylinder members are slidably connected by a connecting member. The connecting member and the first cylinder member are mutually movable with a first stroke length, while the connecting member and the second cylinder member are mutually movable with a second stroke length, and the connecting member is the third stroke.
Has a length of. Thus, according to the invention, the first stroke length is shorter than the second stroke length, which achieves the first object mentioned above.

Further objects of the invention will be apparent from the following description, but features enabling the attainment of 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.

Detailed Description of the Preferred Embodiments For comparison, the accompanying FIGS. 1A and 1B show shoe shoes discussed further in the description below.
Figure 2 shows two different schematic cross-sections of the pressing device as seen across the machine direction MD.

2A and 2B are similar to FIGS. 1A and 1B, but are views of a pressing apparatus having an expansion nip according to a preferred embodiment of the present invention.

The pressing device according to the invention comprises a press shoe 101, for the purpose of squeezing a running web of paper or paperboard, the press shoe being in the machine direction MD.
Transversely aligned and arranged to cooperate with backing member 102 to form expansion nip 103 for passing web 104 during squeezing.

The pressing device can be moved in a direction towards the backing member via a plurality of load cylinders 106 spaced along the press shoe 101 to enable applying pressure to the web during pressing. So as to support the press shoe.
Further includes.

Each load cylinder 106 described above includes a first cylinder member 107 having a first cylinder end 108 attached to or integrated with the press shoe 101, and a support 1.
Second cylinder member 109 having a second cylinder end 110 attached to or integrated with.

The expression “cylinder member” as used herein should be understood as a functional part of a load cylinder, which can be of the hydraulic or pneumatic type. Examples of such "cylinder members" include a generally cylindrical inner or outer sleeve open at least at one end, a substantially cylindrical solid body or piston, or a substantially cylindrical body in a press shoe or support. There is a recess.

The first and second cylinder members 107 and 109 are slidably connected by a connecting member 111, and the connecting member 111 and the first cylinder member 107 are movable with respect to each other by a first stroke length L1 and are also connected. Member 111 and second cylinder member 10
9 is movable with respect to each other by a second stroke length L2, and the connecting member has a third length L3.

The expression “stroke length” as used herein should be understood as the maximum length of said cylinder member available for the sliding displacement of the second cooperating member relative to the cylinder member.

According to the invention and in a preferred embodiment, the first stroke length L1 is shorter than the second stroke length L2.

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.

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 L1.
It is particularly advantageous that the stroke length L2 is longer than the combined length.

In a further advantageous embodiment of the pressing device according to the invention, the connecting member 111 forms a contact seal 112, 113 in order to form at least one working chamber 114.
To slidably connect the first cylinder member 107 and the second cylinder member 109 in a slidable manner to reduce the pressure of a pressurized medium such as hydraulic oil or compressed air within the working chamber to shorten the load cylinder 106. It can be lowered and raised to prolong. Accordingly, the central axis C1 of the first cylinder member 107 and the connecting member 111
The central axes C3 of the cans can be tilted at an angle with respect to each other and with respect to the central axis C2 of the second cylinder member 109 during the intentional or unintentional tilting of the press shoe 101 during pressing. 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 such that during tilting the central axis C3 of the connecting member and the second axis It is adapted to minimize the angle A2 between the central axis C2 of the cylinder member.

Therefore, the above-mentioned inclination can be either intentional or unintentional. The seals 112, 113 can advantageously be of the type disclosed in the above mentioned EP 0933471. The connecting members can also have various geometric shapes, as will be apparent from the following description.

In a further advantageous embodiment of the pressing device according to the invention, shown in particular in FIG. 2B,
Press shoe 1 with shoe support 115 in contact with the shoe support during squeezing
Fixed to a support for accepting the machine direction MD force exerted by 01. In this embodiment, one or several stop means 116 are arranged on the first cylinder member 107 and / or on the connecting member 111 in order to limit the maximum value of the first stroke length L1. Confirms a very small angle A2 between the central axes C3 and C2. In the pressing device 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 a protruding seal 112 surrounding the connecting member 111. However, it is also possible to envisage embodiments of the shoe pressing device according to the invention, in which the stopping means have another suitable design. In connection with this embodiment, FIG.
It should be noted that the shoe press device shown in 1B has no stopping means for limiting the maximum value of its corresponding stroke length l1.

In a further advantageous embodiment of the pressing device according to the invention, the first cylinder member 107 comprises an open third cylinder end 11 opposite the first cylinder end 108 described above.
6, but the second cylinder member 109 includes an open fourth cylinder end 117 opposite 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 is shown in FIGS.
A part of the working chamber 114 is configured as shown in FIG. In an alternative embodiment (not shown in the drawings), the connecting member instead consists of a solid, substantially cylindrical body, at each end of which a working chamber is formed, which may have one or several channels. Due to the pressure connection between the working chambers formed, it can be arranged advantageously but not necessarily between the two ends.

In yet another alternative embodiment (not shown) of the shoe press apparatus according to the present invention, the first and second cylinder members are solid, substantially cylindrical objects, one end of which constitutes a working chamber. Surrounded by a connecting member to form. Thereby the sealing means should be arranged above the connecting member in order to minimize its tilt / distortion according to the invention.

The backing member 102 is a rotatable counter roll, and the flexible belt 1
The embodiment of the invention in which 18 is arranged in an endless loop for running between the press shoe 101 and the paper or paperboard web 104 during pressing is particularly advantageous. Thereby, it is preferred that the flexible belt has the shape of a sleeve.

The pressing device with an expanding nip according to the invention is preferably intended for wet pressing or calendering of paper or paperboard webs.

The following illustrates some of the advantages that can be achieved by the present invention by way of example.

FIG. 1A shows a shoe pressing apparatus with a press shoe in a first position for producing a substantially symmetrical pressure curve through the nip.

FIG. 1B shows the shoe press apparatus of FIG. 1A, where the maximum pressure of the pressure curve is at the end of the nip as compared to when the press shoe is in the first position of FIG. 1A. The press shoe has been intentionally moved to the second position for displacement. As is apparent from FIGS. 1A and 1B, the first stroke length 11 of the illustrated shoe press device is greater than the second stroke length 12.

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, which press shoe 1, and thus it The central axis c1 of the first cylinder member 7 related to [1] is inclined forward in the machine direction MD by the 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 have been exaggerated for clarity.

The large inclination of the connecting member (piston) 11 in the direction towards the shoe support 15 results in the generation of a force component pressing the first cylinder member 7, which leads to a machine direction MD.
Since the press shoe 1 is pressed against the shoe support 15 along with the other forward force, the shoe support 15 is subject to great stress during squeezing.

2A and 2B illustrate a pressing device having an expanding nip according to a preferred embodiment of the present invention. FIG. 2A shows that the press shoe has a first position similar to the first position of FIG. 1A.
2B shows the pressing device in a position, but FIG. 2B shows the pressing device with the press shoe intentionally moved to a second position similar to the second position of FIG. 1B.

In FIG. 2B, the press shoe 101 is deliberately the press shoe 101 in FIG. 1B so that the pressure in the nip can be higher at the end of the nip than at its beginning.
It is tilted about the same as the shoe 1. Therefore, the first cylinder member 10
The angle A1 between the central axis C1 of 7 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 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. 1B. Is significantly smaller than the corresponding angle a2 between C3 and C3. Starting from the example above, the minimization, ie reduction or elimination, of the angle A2 achieved according to the invention is carried out by the press shoe 101 on the shoe support 118.
It should be apparent to those skilled in the art to reduce or even eliminate the force component in the machine direction MD resulting from the pressing of 14.

FIG. 3 shows that the first cylinder member is inclined by a certain angle, and the cylinder members 7 ′, 9 belonging to the load cylinder of the shoe press apparatus when the load cylinder 6 ′ is extended.
The movement pattern of'and the connection member 11 'is schematically shown.

In contrast, FIG. 4 shows that the first cylinder member is inclined by the same angle as in FIG. 3, and the cylinder member 107 ′ belonging to the load cylinder of the pressing device according to the invention when the load cylinder 106 ′ is extended. , 109 ′ and the connecting member 111 ′ are schematically shown.

As is apparent from FIG. 4, the pressing device according to the present invention includes the connecting member 111 ′,
When the load cylinder 106 ′ is extended (or shortened), the load cylinder 106 ′ can be moved substantially linearly and parallel to the extension direction. This minimizes possible stress on the shoe support.

During the extension (or shortening) of the load cylinder 6 ′ of the shoe press device shown in FIG. 3, the connecting member 11 ′ is instead provided with a load cylinder 6 ′, depending on how far the extension or shortening stroke proceeds. It will be tilted at various angles with respect to the extension direction of 6 '. This can cause very high stresses on the possible shoe support, or the press shoe can become unstable when forces are directed in the machine direction (backward in the machine direction). Furthermore, the frictional force between the press shoe and the shoe support changes transversely to the machine direction (resulting in a large distortion of the piston), depending on the greater bending of the support (beam) in the middle. .
This can result in cross machine variations in the machine direction pressure curve of the shoe press.

The invention should not be construed as limited to what has been described herein in relation to various embodiments or shown in the accompanying figures. The scope of the invention is defined by the appended claims.

The mechanical and hydraulic, alternatively pneumatic, components included in the shoe press apparatus according to the present invention, these components should be well known to those skilled in the art,
Further, it is disclosed and discussed in the above-mentioned European Patent No. 0933471 and is therefore not described in detail here.

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 drawings]

FIG. 1A is a press for the purpose of generating a nearly symmetrical pressure curve through a nip.
FIG. 3 is a schematic cross-sectional view of the shoe press apparatus as seen in the machine direction, with the shoe in the first position.

FIG. 1B is an intentional press shoe to move the pressure maximum of the pressure curve toward the end of the nip as compared to when the press shoe is in the first position shown in FIG. 1A. FIG. 1B shows the shoe press apparatus of FIG. 1A moved to a second position in FIG.

2A is a view similar to FIG. 1A, but with the press shoe in a first position similar to the first position in FIG. 1A, with a widening nip according to a preferred embodiment of the present invention. .

2B is a view of the pressing apparatus according to the present invention in FIG. 2A, but with the press shoe 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 belonging to a load cylinder of a shoe press device and a connecting member when the first cylinder member is inclined at an angle to lengthen the load cylinder.

4 is a schematic movement pattern of a cylinder member and a connecting member belonging to the load cylinder of the pressing apparatus according to the present invention when the first cylinder member is inclined at the same angle as in FIG. 3 to lengthen the load cylinder. FIG.

─────────────────────────────────────────────────── ─── Continued front page    (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, I T, LU, MC, NL, PT, SE, TR), OA (BF , BJ, CF, CG, CI, CM, GA, GN, GW, ML, MR, NE, SN, TD, TG), AP (GH, G M, KE, LS, MW, MZ, SD, SL, SZ, TZ , UG, ZW), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), AE, AG, AL, AM, AT, AU, AZ, BA, BB, BG, BR, BY, B Z, CA, CH, CN, CR, CU, CZ, DE, DK , DM, DZ, EE, ES, FI, GB, GD, GE, GH, GM, HR, HU, ID, IL, IN, IS, J P, KE, KG, KP, KR, KZ, LC, LK, LR , LS, LT, LU, LV, MA, MD, MG, MK, MN, MW, MX, MZ, NO, NZ, PL, PT, R O, RU, SD, SE, SG, SI, SK, SL, TJ , TM, TR, TT, TZ, UA, UG, UZ, VN, YU, ZA, ZW [Continued summary] it can.

Claims (14)

[Claims] An expansion nip cooperating with a backing member (102) for passage of said web (104) during pressing in a pressing device having an expansion nip for pressing a running web of paper or paperboard. A press shoe (101) oriented transversely to the machine direction (MD), arranged to form (103), and a press shoe for enabling the application of pressure to the web during pressing. Shoe (1
01) for supporting the press shoe movably toward the backing member through a plurality of load cylinders (106) spaced apart along the press cylinder (106), each load cylinder (106) comprising: It has a first cylinder member (107) having a first cylinder end (108) attached to or integrated with the shoe (101) and a second cylinder end (110) attached to or integrated with a support (105). Second
A cylinder member (109), and first and second cylinder members (107, 10).
9) is slidably connected by a connecting member (111),
1) and the first cylinder member (107) are mutually movable by the first stroke length (L1), but the connecting member (111) and the second cylinder member (109) are only the second stroke length (L2). A press device, wherein the first stroke length (L1) and the second stroke length (L) are mutually movable and the connecting member has a third length (L3).
2) Pressing device with extended nip, characterized by being shorter. 2. Pressing device with an expansion nip according to claim 1, characterized in that the first stroke length (L1) is less than half of the second stroke length (L2). 3. The first or second stroke length (L3) is greater than both the first stroke length (L1) and the second stroke length (L2).
A press device having an extended nip according to claim 1. 4. A third length (L3) is greater than the sum of the first stroke length (L1) and the second stroke length (L2). Device with extended nip. 5. The connecting member (111) has at least one working chamber (114).
The first cylinder member (107) and the second cylinder member (109) are slidably connected to each other by contact seals (112, 113) in order to form the pressure of the pressurizing medium inside the working chamber. Can be lowered to shorten the load cylinder (106) and raised to extend, thus the first cylinder member (107).
) Central axis (C1) and the central axis (C3) of the connecting member (111) with respect to each other and during the intentional or unintentional tilting of the press shoe (101) during pressing.
A press device with an extended nip according to any one of the preceding claims, which is tiltable at an angle to the central axis (C2) of the cylinder member (109), the first stroke length (L1). ), Second stroke length (L2), third length (L3)
), And the geometrical position of the contact seals (112, 113) is such that the angle (A
Pressing device with an expanding nip, characterized in that it is adapted to minimize 2). 6. A shoe support (115) secured to a support for receiving a machine direction (MD) force exerted by a press shoe (101) in contact with the shoe support during squeezing. A pressing device with an expanding nip according to any one of the preceding claims, comprising one or several stop means (11).
6) is arranged on the first cylinder member (107) and / or on the connecting member (111) in order to limit the maximum value of the first stroke length (L1), Press machine with expansion nip. 7. A first cylinder member (107) is provided with the first cylinder end portion (1).
08) including an open third cylinder end (116) opposite the second cylinder member (116).
109) includes an open fourth cylinder end (117) opposite the second cylinder end (110), a third cylinder end (116) and a fourth cylinder end (117).
Said connecting member (in order to form one or several working chambers (114).
111) Pressing device with an expanding nip according to claim 5 or 6, characterized in that it encloses each end of (111). 8. Pressing device with expansion nip according to claim 7, characterized in that the connecting member (111) is a substantially cylindrical sleeve, the interior of which constitutes a part of the working chamber (114). . 9. The press device having an expansion nip according to claim 7, wherein the connecting member is a solid, substantially cylindrical object, and working chambers are formed at both ends thereof. 10. A cylindrical object is provided between the two ends for pressure communication between the working chambers.
Pressing device with an expanding nip according to claim 9, characterized in that it comprises one or several channels. 11. The first and second cylinder members are solid, substantially cylindrical objects, one end of which is surrounded by a connecting member to form a working chamber, and the sealing means is the connecting member. Pressing device with an expanding nip according to claim 5 or 6, characterized in that it is arranged above. 12. A backing member (102) is a rotatable counter roll, a flexible belt (118), preferably in the form of a sleeve, with a press shoe (101) and paper or paperboard during pressing. Pressing device with an expanding nip according to any one of the preceding claims, characterized in that it is arranged in an endless loop for traveling to and from the web (104). 13. Pressing device with expansion nip according to claim 1, which is intended for wet pressing of paper or paperboard webs. 14. Pressing device with an expansion nip according to claim 1, which is intended for calendering paper or paperboard webs.