FI107063B - Long nip press for a papermaking or board-making machine - Google Patents

Abstract

The long nip N is formed between a mating roll 50 and a shoe roll 10, which shoe roll 10 comprises a stationary bearing structure 12 and a flexible casing 30 rotating around this. The casing 30, from its inner face, is supported on the bearing structure 12 by means of a press shoe 11 and load members 14, 20, 114, 120 connected to the latter and situated at a distance apart in the machine direction in at least one row. The load members comprise a first cylinder 14 supported on the bearing structure 12 and a piston 20, 120 fitted in the said cylinder, the press shoe 11 and the surrounding casing 30 being able to be loaded against the mating roll 50 by means of the said loading members. The first cylinder 14 is arranged movably in a plane perpendicular to the centre axis of the first cylinder 14 in a cylindrical base part 13, which base part 13 is fixed to the bearing structure 12. The first cylinder 14, moreover, is relieved of load in the radial direction by means of a pressure medium fed into a pressure chamber 18, 118 in the first cylinder 14, which pressure medium also loads the press shoe 11. <IMAGE>

Description

107063

The present invention relates to a paper or board machine long nip press according to the preamble of claim 1. The invention relates to a paper or board machine long nip press.

One problem associated with long nip presses is the different thermal expansion movements due to the different temperatures of the press shoe and the load bearing support structure. In a situation where the temperature of the press shoe of a 10 m wide machine is about 50 ° C higher than the temperature of the support structure, about 2.5 mm elongation with respect to the support structure occurs at the ends of the centrally supported steel press shoe. The thermal expansion movement greater than the load-bearing shoe carrier structure causes lateral forces, lateral frictional forces and possible deflection of the press shoe on the cylinder-piston actuators supporting the press shoe. In turn, the foregoing causes inaccuracies in compression loads and errors in the moisture profile.

Many different solutions to this problem have been presented in prior art publications. The following describes some such prior art solutions.

20: Applicant's European Patent Publication No. 933471 discloses a paper or board machine pit; · Tweezers. The press clamping shoe is supported on the bracket structure by several joints: · *: equipped with a hydraulic dip cylinder. Each loading cylinder comprises a piston: and a first cylinder mounted on a press shoe and a second cylinder mounted on a support structure. The opposite end portions of the piston are slidably and sealingly fitted to said cylinders. whereby pressure spaces are formed in the cylinders under the opposite end surfaces of the piston ·· «· ... ·. The pressure medium supplied to the pressure rooms can be used to · · · press the press shoe against the back roll. In such a solution, the piston may pivot about: about 30 axes perpendicular to and perpendicular to the machine direction. This allows deformation and thermal expansion of the clamping shoe and allows the clamping shoe to pivot perpendicular to the machine direction; · · · Around.

107063 Ί

Another longitudinal piping cross for a paper or board machine is disclosed in Applicant EP 345501. At its underside, the press shoe of the press is supported on the roll support structure by two axial rows of cylinder-piston actuators. The support is formed between the rounded outer ends of the piston pins attached to the pistons and the lower surface 5 of the press shoe. In addition, a series of bushings extending between the bores formed in the press shoe are attached to the bracket structure between the piston pin rows. The sleeves are fitted to the bores of the press shoes by means of flexible seals. The press shoe is further supported in the machine direction by a support member formed at one end of the support structure by a roller member for receiving horizontal forces 10 on the press shoe. The clamping shoe thus rests floating on the piston pins, allowing a slight axial movement and tilting of the clamping shoe.

Applicant's DE utility model 298 17 097 UI discloses a third long nip press for a paper or board machine. The cylinder piston actuator for loading the press shoe 15 consists of a piston removably attached to the support structure and which is sealed to a cylinder supported on the press shoe. The load shoe is horizontally movably mounted on the bottom plate of the cylinder. Figure 2 shows an embodiment in which the bottom plates of the cylinder define the clamping shoe · _; a chamber opening against the underside. This chamber and the hydrostatic pressure chamber at the face of the press shoe are supplied with pressure medium from a common source of pressure medium. whereby the pressure in both chambers is the same. The pressure in the hydrostatic pressure chamber is generally about 50-70% of the pressure in the pressure chamber of the load cylinder, leaving j "" * the radial load on the cylinder, depending on the areas; ***; about 30-50 ° o without compensation. Thus, the clamping force between the clamping shoe and cylinder • • · 25 varies according to the loading condition of the loading cylinder, so that there may be significant frictional forces between the clamping shoe and the * · m: ί cylinder to prevent lateral displacement of the clamping shoe. The side of the piston fitted to the cylinder is curved,. whereby the cylinder may pivot somewhat with respect to the piston. The actual invention herein relates to the fact that the piston is attached eccentric to the support structure. By loosening the 30 piston fastenings and changing the position of the eccentric fastening blocks, the piston and, thus, the cylinder can also be moved in the machine direction with respect to the press shoe. In this way, the pressure profile of the web passing through the press can be changed 107063 3 to obtain an optimum profile for different paper and board grades.

U.S. Patent No. 5,688,375 (Voith) discloses a fourth pit-5 tweezer for a paper or board machine. The cylinder-piston actuator for loading the press shoe of the press consists of a cylinder formed in the support structure and fitted with a piston. The lower part of the piston has a projection portion which is sealed to the cylinder walls through seals. The piston forms at its lower end a first pressure chamber which opens into the cylinder. The piston further forms, in its upper part, a second pressure chamber opening on the underside of the press shoe 10, which communicates with the first pressure chamber via a capillary channel. The piston is sealed at its edges with seals on the underside of the press shoe. The pressure medium flows through the capillary channel under almost constant conditions from the first pressure chamber to the second pressure chamber and thus to the underside of the press shoe. As the press shoe tilts, the pressure medium can escape from the second pressure chamber, thereby preventing the first pressure chamber from rapidly flowing through the capillary tube with sufficient replacement pressure medium. As a result, the pressure drops in the second pressure chamber, whereby the piston aligns itself with respect to the underside of the press shoe by the pressure applied in the first pressure chamber.

It is an object of the present invention to provide a paper or board machine. nipple clamp to avoid loads due to thermal expansion and frictional forces: ·; vague tilt, tilt, and profiles.

The paper or board test long nip press according to the invention is essentially characterized by what is set forth in the characterizing part of claim 1.

In the long nip press according to the invention, movement between the press shoe and the support structure: * is allowed. The structure of the invention further enables the press shoe • · ·:: low friction and precise positioning and loading on the back roller as well as the delicate tilt adjustment.

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In the following, the invention will be described in detail with reference to various embodiments of the invention shown in the figures of the accompanying drawings, the details of which, however, are not intended to be solely limited thereto.

Fig. 1 is a schematic view of an embodiment of the construction of a long nip press according to the invention.

Figure 2 is an enlarged detail of Figure 1.

Figure 3 is a schematic view of another embodiment of the construction of a long nip press according to the invention.

Figure 4 is an enlarged detail of Figure 3.

Fig. 5 is a diagrammatic view of the structure of the long nip press shown in Fig. 1, transverse to the machine direction, with the press shoe loaded with a single row of cylinders.

·. ; Fig. 6 schematically shows a transverse direction of the machine direction in a third embodiment of a long nip press construction according to the invention.

. ; Fig. 7 is a diagrammatic view of the transverse direction of the machine direction I: the structure of the long nip press shown in Fig. 1 in a situation where the press shoe is loaded with two rows of cylinders.

Fig. 1 is a schematic view of the loading system between the press shoe 11 and the static ... * static support structure 12 when viewed in the machine direction. Load arrangement form; The base member 13 comprises an annular portion 13a, a cylindrical portion 13b, and a bottom lip 13c. which closes the lower end of the cylindrical portion 13b. The cylindrical portion 13b and the bottom plate 13c of the base portion 13 here consist of a single piece and the annular portion 13a consists of a separate piece. The cross-section of the wall of the first cylinder 14 fitted to the base portion 13 is substantially inverted T-shaped, comprising a horizontal mandrel 14a forming the lower portion of the wall and a vertical mandrel 14b forming the upper portion of the wall. The inside diameter D4 of the cylindrical portion 13b of the base portion 13b is slightly larger, preferably about 6-10 mm, than the outer diameter D3 of the horizontal shaft 14a of the first cylinder 14 5 fitted to the base portion 13. The first cylinder 14 is locked in the radial direction by an annular portion 13a of the base portion 13 which rests around the first cylinder 14 on a horizontal mandrel 14a and abuts the end surface above the cylindrical portion 13b. Instead, the first cylinder 14 may move transversely to the central axis Y2 of the first cylinder 14 in a housing 22 having a suitable clearance 10 formed in the base portion 13.

The base plate 13c of the receiving base portion 13 of the first cylinder 14 has a cylindrical recess 18a extending at least a distance below the horizontal mandrel 14a of the wall of the first cylinder 14. In this way, access to the pressure medium 15 introduced into said recess 18a is provided under the horizontal mandrel 14a of the first cylinder 14. The horizontal mandrel 14a of the first cylinder 14 is sealed to the base plate 13c of the base member 13 by an annular seal 17. The central diameter D1 of the annular seal 17 mounted on the base plate 13c of the base member 13 is approximately equal to the inner diameter defined by the vertical wall. that is, the inside diameter D2 of the piston 20 receiving the piston 20 fitted to the first cylinder 14. The pressure medium can thus be influenced by 'i «•; the lower surface of the horizontal shaft 14a of the first cylinder 14 having an area approximately equal to *; · · Large than the area on the upper surface of the horizontal mandrel 14a affected by the pressure medium. With such an arrangement, the first cylinder 14 can be lightened radially so that the · · ·! >> t! the friction between the contact surfaces of the first cylinder 14 and the base member 13 can be minimized. As a result, the first cylinder 14 may, if necessary, move freely in a plane 22 having a suitable clearance 22 in the plane perpendicular to the central axis Y2 of the first cylinder 14 and having a center diameter D1 of the gasket 10%, preferably within ± 5%. If this ratio is within ± 5%, there would be a difference between the above and below pressurized areas of the above horizontal bar 14a of the first 30 cylinders 14. j about ± 10% and the radial force acting on the frictional force to prevent lateral movement would be up to about 10% of the cylinder force. Using a friction coefficient of 0.3, the frictional force resisting the lateral movement of the first cylinder 107063 6 would then be at most about 3% of the cylinder force.

The pressure medium 18 is introduced into the pressure chamber 18 5 of the piston 20 disposed within the first cylinder 14 by a pressure medium conduit 23 consisting of a pressure medium flow opening 23b extending through a base plate 13c of a base 13 and a fluid opening 23a sealing 24. The pressure medium flow opening 23b extending through the base plate 13c of the base member 13 is located substantially in the center of the base plate 13c of the base member 13 and opens into the cylindrical recess 18a of the lower chamber 18.

The piston 20 disposed within the first cylinder 14 comprises fastening means. e.g., a portion 20a secured by bolts 21 to a press shoe 11 and a portion 20b having a planar upper and lower surface and a spherical sidewall below it. The radius of curvature of the spherical side edge of the piston 20 is denoted by the reference R 1. The portion 20b having a spherical side edge of the piston 20 is sealed to the inner surface of the vertical wall 14b of the first cylinder 14 by an annular seal 19 at the widest point of the side edge. This design allows the piston 20 to tilt]. in the range of about 3-5 °.

«I

In the situation illustrated in Figure 1, the first cylinder 14 is located in the middle of the housing 22 formed by the base member 13. Then, the vertical center axis Y1 of the base member 13 is aligned with the center axis Y2 of the first cylinder 14.

Figure 2 shows an enlarged detail of the first cylinder 14 of Figure 1.

: the junction area of the chassis 13 and the bracket 12. It will be seen from the magnification that the · · * * base portion 13 is secured to the support structure 12 by means of fastening means extending through the annular portion r * * 30 13a of the base portion 13 and the cylindrical portion 13b of the base portion. e.g.

• · ·.,. The bolts 16. The magnification also shows that the recess 18a formed in the base plate 13a of the base member 13 continues as a shallow slot 15 all the way to the seal 17. This ensures 7107065 that the pressure medium can act all the way to the gasket 17 and that the gasket 17 nevertheless has a sufficient support surface on both the inner and outer periphery. To prevent the first cylinder 14 from being subjected to frictional forces caused by radial forces that resist lateral movement, the effective pressurized diameter D15 of the recess 18a of the base 13a should be equal to the inner diameter D2 of the first cylinder 14. Depending on the type of gasket, it is difficult to obtain an exact and correct effective diameter, but the so-called gauge shown in the figures. With the O-ring gasket, the center line diameter D1 of the gasket 17 is approximately the correct effective diameter.

Figure 3 is a schematic view of the machine direction of an alternative peeling step between the press shoe 11 and the stationary support structure 12. The load distribution shown in Figure 3 differs from the load distribution shown in Figure 1 with respect to the base portion 13. The base member 13 has no bottom plate at all, but instead the first cylinder 14 is sealed directly on the upper surface of the support structure 12 by an annular seal 17 disposed on the underside of the horizontal arm 14a of the first cylinder 15 14. 14a. The cylindrical portion 13b and the annular portion 13a here consist of a single piece. The first cylinder 14 may move in a plane perpendicular to the central axis Y2 of the first cylinder 14 in the support structure | in a housing 22 with suitable clearances delimited by the tea 12 and the base 13.

Figure 4 shows an enlarged detail of the first cylinder 14 of Figure 3.

: ***: in the joining area of the base member 13 and the supporting structure 12. The magnification shows that the en- • · ·! A gap 15 extends between the lower surface 14a of the horizontal shaft 14a of the first cylinder 14 and the upper surface of the support structure 12. This slot 15 secures access of pressure medium • · · to the seal 17 under the horizontal shaft 14a of the first cylinder 14. However, the seal 17 * * * * ... · has sufficient support surface on both the inside and outside. Thus, in this embodiment is: the same basic idea as in the embodiment shown in Figure 1, i.e., the pressure medium acts: on the underside of the cylindrical horizontal mandrel 14a, approximately the same area as it acts. ·: ·. on the upper surface of the horizontal arm 14a.

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Fig. 5 is a schematic view of the structure of the long nip press shown in Fig. 1 in a transverse direction to the machine direction, with the press shoe 11 loaded with one cylinder row 14. The figure shows how the web W is guided in the long nip supported on the support structure 12 by the supporting members 41, 42 on both sides of the loading member 11, the supporting members 41, 42 receiving the machine direction forces exerted by the clamping head 11 of the belt shell 30 and the counter roll 50. The first support member 42 in the machine operating direction S is not necessary because in the operating state the friction force presses the press shoe 11 against the leaving member support member 41.

10

Fig. 6 is a diagrammatic view of a third embodiment of the structure of a long nip press in accordance with the machine direction. In this embodiment, the piston 120 is not secured to the clamping shoe 11, but the piston 120 rests at its upper end on a second cylinder 114. which is attached to the clamping shoe 11. The second cylinder 15 114 consists of a bottom plate 114a and a cylinder sleeve 114b. The bottom plate 114a is supported on the underside of the press shoe 11 by a flange 113 surrounding the bottom plate 114a and the flange 113 is secured to the underside of the press shoe 11 by means of fastening 21. e.g. by bolts. In this embodiment, the piston 120 is formed by an underside portion 122 with a spherical side surface and an upper portion 123 with a spherical side surface and 20 intermediate portions 121 connecting them. The lower part 122 of the piston 120 is sealed by a . The upper portion 123 of the piston 120, in turn, is sealed to the second cylinder 114 by the annular seal 125 «· · 25 at the widest point of the upper portion 123 of the spherical side surface. The intermediate portion 121 here consists of a cylindrical sleeve. The underside portion 122 of the piston 120 is locked against sliding out of the first cylinder 14 by a first

Ml with a locking ring 160. facing the end surface of the vertical shaft 14b of the cylinder 14 which is fixed to said end surface by means of fastening, e.g. bolts 161.

· ': 30 of a spherical lateral surface 122 of the piston 120 and 122 of the upper portion. . . due to the pin, the piston 120 may be inclined relative to the first 14 and second 114 cylinders.

This design allows the piston 120 to be tilted in the range of about 3-5 °.

9 107065

The press shoe 11 is supported by a support member 130 against machine direction S forces. Further, the press shoe 11 is provided with a pin 131 whose outer end rests on a slot 132 formed in the support member 130. In such an arrangement, the press shoe 11 can move freely 5 in and out of the embossing roll 50 in the embossing direction, but movement of the press shoe 11 transverse to the machine direction.

A flange 150 provided with a lubricating oil supply channel 151 is secured to the opposite edge of the press member 11. From said supply channel 151, the lubricating oil 10 is fed to the oil pocket 140 of the press shoe 11 via bores 141 formed in the press shoe 11.

A pressure medium 118 is introduced into the pressure chamber 118 defined by the first cylinder 14, the second cylinder 114 and the piston 120 therefrom through a pressure medium flow port 23 provided in the support structure 12. The primary cylinder 14 and associated support structure corresponds to the embodiment shown in FIG. embodiment.

The upper end and lower end of the piston 120 may also be closed by end plates, whereby a first pressure chamber is formed in the space defined by the first end cylinder 14 and the lower end plate of the piston 120 and a second pressure chamber 1 is formed. The first and second pressure chambers can be combined ·: **; a pressure medium passage through the piston 120 through which the pressure medium to be supplied to the pressure chamber below the piston 120 is transported to the pressure chamber above the piston 120. The press shoe 11 may also be followed by a fluid passage for the pressure medium, with flow openings to the second cylinder 114. The connection between the pressure chambers can then be provided through the communication channels between the support structure 12 and the press shoe 11.

Figure 7 schematically illustrates, in transverse direction to the machine direction, the structure of the long nip press shown in Figure 1 in a situation where the press shoe 11 is loaded with two causes 1, 300, 400. The only difference with the situation of Figure 5. that ·; ··· two cylinder rows spaced apart in the machine direction 10 107062 300, 400 instead of one cylinder row are used here. The cylinders of each of the cylinder rows 300, 400, with their support structures, correspond exactly to the structure shown in Figures 1, 2 and 5. Of course, the alternative shown in Figures 3, 4 or 6 may also be used. With two rows of cylinders, different pressures can be applied and the shape of the compression pressure curve can be controlled.

5

In the solution of the invention, the same pressure medium is used to load the press shoe 11 also to lighten the first cylinder 14. The lightening of the first cylinder 14 is thus independent of the prevailing loading situation. The upper surface of the horizontal shaft 14a of the first cylinder 14 in the pressure chamber 18, 118 is gold-plated with the same pressure medium as the lower surface defined by the seal 17 of the horizontal shaft 14a of the cylinder. When the said areas are equal, the first cylinder 14 is always completely lightened, whereby the first cylinder 14 can move with very little friction in a plane perpendicular to the central axis Y2 of the first cylinder 14.

The claims which follow, within the scope of which the inventive idea is defined, may vary and depart from those set forth above by way of example only.

• «» · «·« • · · • «« «« * * * * * 4 »»

Claims (8)

A longitudinal nip press for a paper or board machine, wherein the long nip (N) is formed between a counter roll (50) and a shoe roll (10), which shoe roll (10) comprises a stationary support structure (12), a flexible sleeve (30) is supported on its inner surface by a support structure (12) transverse to the clamping shoe (11) and associated machine direction, at least in one row by means of loading members (14, 20, 114, 120), 114, 120) comprising a first cylinder (14) supported on the support structure (12) and a piston (20, 120) directly or indirectly supported thereon on the press shoe (11), wherein the press shoe (11) and the surrounding sheath (30) are loadable against the counter roll (50) with said load members (14, 20, 114, 120), characterized in that the first cylinder (14) is arranged in the central axis of the first cylinder (14) (13) movable in a plane perpendicular to (Y2), the base member (13) being fixed to the support structure (12), and the first cylinder (14) being lightened radially by a pressure medium fed to the pressure chamber (18) of the first cylinder (14) , which also pressures the press shoe (11) with the pressure medium. Long nip press according to claim 1, characterized in that it is directly pressed. The piston (20) supported by the 20 shoe (11) comprises a stationarily attached portion (20a) of the shoe (11) and a spherical side portion (20b) beneath it, which is fitted with an annular sealing member (20b) on the spherical side surface. ; ··· tea (19) sealed to first cylinder (14). • * ♦ · · «« ·:: 25 The long-nip press according to claim 1, characterized in that the piston (120) indirectly supported by the press shoe (11) comprises a lower part (122) with a spherical sidewall, which is fitted with an annular seal (124) on the annular sidewall. ) sealed to a first cylinder (14) and an upper portion (123) having a spherical: side surface disposed on a second cylinder (114) sealed to the underside of a press shoe (11) by means of an annular seal (125) an intermediate portion (121) connecting the portion (122) and the upper portion (123). 107065 12 The long nip press according to any one of claims 1 to 3, characterized in that the wall of the first cylinder (14) has a substantially inverted T-shape comprising a horizontal mandrel (14a) and a vertical mandrel (14b) and that the base member (13) 5 comprises a first cylinder (14). 14) a spaced-apart cylindrical portion (13b) surrounding the horizontal spindle (14a) supported on an upper surface of a support structure (12) and an annular portion (13a) over a horizontal spindle (14a) of the first cylinder (14), the annular portion (13a) of the base member (13) prevents radial movement of the first cylinder (14) and the cylindrical portion (13b) of the base member (13b) allows movement of the first cylinder (14) perpendicular to the center axis (Y2) of the first cylinder (14) . The long nip press according to claim 4, characterized in that the base part (13) further comprises a base plate (13c) which closes the lower end of the cylindrical part (13b) of the base part (13). having a cylindrical recess (18a) extending some distance from the bottom of the horizontal mandrel (14a) of the wall of the first cylinder (14) fitted to the base portion (13) so that the horizontal mandrel (14a) is sealed by an annular surface around the cylindrical recess (18a) (17). wherein the pressure medium is introduced from the flow opening (23b) through the bottom plate (13c) into said recess (18a), from where the pressure fluid 20 spreads to the pressure chamber (18, 118) and to the area defined by the seal (17) of the first cylinder; below the horizontal arm (14a). The long nip press according to claim 4. characterized in that the horizontal spindle (14a) of the cylinder (14) is sealed on the upper surface of the support structure (12) with a horizontal spindle (14a) with a ring-shaped seal (17) fitted to the bottom spindle (14a); a gap (15) extending between the upper surface of the carrier structure (12) and extending into the seal (17) is introduced into the pressure chamber (18. 118) from the pressure medium conduit ... * (23) formed in the carrier structure (12). from which the pressure medium also spreads to the limited area of the seal (17) below the horizontal shaft (14a) of the first cylinder (14). 30 A long nip press according to any one of claims 4 to 6, characterized in that the support n; the inner diameter (D4) of the cylindrical portion (13b) of the portion (13) is preferably about 6 to 10 mm 107065 13 larger than the outer diameter (D3) of the horizontal shaft (14a) of the first cylinder (14) fitted to the base portion (13). Long nip press according to one of Claims 5 to 7, characterized in that the effective sealing diameter (17) of the first cylinder (14) between the horizontal spindle (14a) and the bottom surface (13c) of the base (13c) or the upper surface of the bracket structure (12). D1) the ratio to the inner diameter (D2) of the first cylinder (14) defined by the vertical spindle (14b) is within ± 10%, preferably within ± 5%. •••••••••••••••••••••• 107063 14