FI112263B - Paper machine press section - Google Patents

Description

112263 5

Paper machine press section Pressparti i en pappersmaskin

The invention relates to a closed press section of a papermaking machine according to the preamble of claim 1.

In the prior art, the so-called. In COMBI presses, the first press nip 10 is formed in connection with a pick-up suction roll between it and a smooth surface center roll. In the center roll, there is another single-felt press nip opposite the pick-up roll. The paper web is then separated from the second press felt and transferred from the center roll by a short open draw using a paper guide roll to either the dry press section or to the next separate press nip, which has previously been generally a roll nip.

Said COMBI presses are most commonly used on relatively narrow and low power paper machines having speeds of the order of 20,400-500 m / min. COMBI presses are especially used in multi-mode machines, where the basis weights of the paper produced can vary within wide limits, for example in the range of 30-270 g / m2. The paper to be produced at the lower limit of said basis weight range is e.g. cigarette paper or framed paper and the upper limit is thick paper already close to the paperboard.

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Recently, many paper machines equipped with COMBI presses have been modernized to increase the machine speed typically within the range * * »· · to 800-1000 m / min and possibly also to expand the range and basis weight of the paper grades being manufactured.

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Placement of Long Nip Shoe Press in COMBI Type Press; : When upgrading to a tiny environment, it is often difficult because the space is tight. The production speed of COMBI presses is already limited by open export after two nips. The old COMBI presses are low, which; · Creating the right 35-felt felt geometry for a shoe press is difficult when modernizing ···.

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It is an object of the present invention to provide new solutions to the problems discussed above, and in particular to a novel press section concept for modern combinations of COMBI presses. It should be noted, however, that the press section of the invention can also be used in new-structure paper machines at higher speeds than the aforementioned speed range. Particularly well, the press part according to the invention is intended to be suitable for use in so-called. multi-type machines for specialty paper grades.

It is a further object of the invention to provide a COMBI-type press section capable of eliminating open track openings for the purpose of increasing the speed potential of the press section.

It is a further object of the invention to provide a press section in which the paper web 15 can be run at full width through the press section to the first drying cylinder of the dryer section, whereby the web can be guided to the wreck in the intermediate stage without having to lower the web before the separate press nip.

It is a further object of the invention to provide a press section capable of achieving good roughness symmetry of opposite surfaces of a paper web.

* ·> · * · «; It is a further object of the invention to provide such a COMBI-type press section which is advantageous in the rebuilds because it can utilize many of the old components of the rebuilding press section.

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In order to achieve the foregoing and further objects, the invention is essentially characterized by what is stated in the characterizing part of claim 1.

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The press section according to the invention achieves the following advantages: the open export from the central roller is eliminated and the press is completely closed with its web entry, which increases its speed potential, since conventional paper-roll roll assisted open export is not applied; the construction of felt geometries in the shoe press largely utilizes parts of an old press, keeping costs under control.

According to the invention, two roll nipples are formed in substantially conventional manner on opposite sides of the central roll, the first nip being formed in connection with the pick-up roll and the pick-up felt. In addition to said roll nipples, the press section of the invention includes, as a closed press concept, a separate nip, which is preferably a long nip press attached to a shoe roll to ensure a sufficiently high drainage capacity. In some cases, especially when the paper machine is primarily intended for the manufacture of thinner grades and / or the machine operates at a relatively low speed range, butter can be used; :; said separate nip also implements as a roll nip. From the last> * · '25 individual nipples, the web is taken to the drying wire of the drying section following the press section as a closed export.

In the following, the invention will be described in detail with reference to certain embodiments of the invention shown in the figures of the accompanying drawings, in which details the invention is not limited.

Fig. 1 shows a first exemplary embodiment of the invention in a schematic side view.

Figure 2 shows another embodiment of the invention as a schematic side view.

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Fig. 3 shows a variation of the press member of Fig. 1, mainly with respect to the initial part of the drying member and the passage therewith.

Fig. 4 shows a modification of the press member of Fig. 2, mainly with respect to the initial part of the drying member and the passage therewith.

First, an embodiment of the invention and its operation as shown in Figures 1 and 3 will be described. The paper web W is sucked from the wire 10 to the press felt 12 by the vacuum of the suction zone 13a of the press suction roll 13 at the pick-up position 10 P. The web W is then pressed at the first nip N1 (formed by the press suction roll 13 and the press roll 14) The pick-up roll 13 has an enhanced suction zone 13b in the Nx region of the nip 14. From the center roll 14, the track W is aspirated to the underside of the second press felt 15 by a second press suction roll 16. The suction roll 16 has a suction zone 16a 15. The main function of the second press suction roll 16 is to act as a transfer suction roll, but it can also remove water from the web W, preferably in the lightly loaded second nipple N2. Felt On the upper surface of the 17, the track W is passed through a long nip NP3 which • * ·; , * formed by shoe roll 19 in lower position and • · f in upper position; a smooth-faced roll 20. Shoe roll 19 has a flexible hose jacket 19b and • · t 25 inside it, at nip zone NP3, hydraulically loaded, press shoe 19a.

• t!,! In Figure 1, the web W is moved from the smooth surface 20 'of the roll 20 to the upper surface of the transfer web 22 by the vacuum of the suction zone 21a of the suction roll 21.

From the transfer wire 22, the track W is further led to the drying wire 23 by the vacuum of the suction zone 24a of the suction roll 24 and further to the drying cylinders 25 in the threading or malfunctioning and its sinking pattern. rile 26 to guide the full-width wreckage track WS to the ··· wreck system below (not shown). Thus, a full-width web can be passed through 35 without lowering the entire press section to the first drying »» V * cylinder 25.

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Figure 3 shows a modification of the press section of Figure 1 which does not use a transfer wire 22 after the last nip NP3. As shown in Figure 3, the web W is transferred from the surface of the long-nip NP3 smooth surface 20 'to the upper surface 20 of the drying wire 23 by means of a suction roll 24A 5. In Figure 3, the transfer suction roll 24A forms a lightly loaded transfer nip NS with a long nip NP3 upper roll 20 so that the completely closed transfer of the web from the forming wire 10 to the drying wire 23 is accomplished, as in Figure 1. shown above with an overflow hood 29 located above the drying wire 23, the function of which is to blow hot air over the web W.

Figures 1 and 3 further illustrate pick-up felt restorers 15 28a, top felt 15 restorers 28b, and lower felt 17 restorers 28c. Further, inside the lower felt loop 17, after the transfer suction roll 18, there is a blow simulation box 27a. The corresponding blow simulation box is within the loop of the transfer stream 22 after the transfer suction roll 21 and the third blow simulation box 27c is located within the loop of the drying wire 23 after the transfer suction roll 20 24. Corresponding devices 27a, 27b, 27c and 28a, 28b, 28c are described below in the embodiments of the invention according to Figures 2 and 4.

* · · * The following shows the embodiments of the invention according to Figures 2 and 4, *, 25. The web W is aspirated from the wire 10 to the press felt 12 and further to the transfer belt 27A by the vacuum of the suction zone 13a of the press suction roll 13. The track W is then compressed in the first nipple N1 # 1 · ·!.! formed by a press suction roll 13 and a central roll 14 of the press 14. The surface 14 "of the central roll · 14 does not necessarily have to be smooth, since 30 transfer belts 27A are used which are preferably substantially non-retractable * * ·

* and a smooth belt component on the outside. From conveyor belt 27A, track W

·, * 1 is aspirated onto the lower surface of the second press felt 15 by the vacuum of the suction zone 16a of the suction roll 16. The main function of this suction roll 16 is to act as a transfer suction roll, but it can also remove * ·! '35 water from the web at the other relatively lightly loaded nipple v; N2.

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In Figures 2 and 4, the web W is moved from the lower surface of the felt 15 to the upper surface of the third lower press felt 17 by the vacuum of the suction zone 18a of the transfer suction roll 18. The lower felt 17 and the transfer belt 28A above it are guided through the longitudinal nipple NP3 formed by the shoe roll 19 in the lower position and the roll 20 in the upper position. However, the upper roll 20 may have a smooth surface 20 "which is not necessary. The shoe roll 19 has a flexible hose jacket 19b and a hydraulically loaded compression shoe 19a therein, after the long nip zone NP3 10. further to the drying wire 23 by means of the vacuum of the suction zone 24a of the suction roll 24 and further to the drying cylinder 25 and its scraper 15 patterns 26.

The press of Fig. 2 can also be used with a blow-through type drying section. In this case, the initial part of the drying section is different from Figure 2 and according to Figure 4, in which the web W 20 is transferred from the surface of the transfer belt 28A to the upper surface of the drying wire 23 by the vacuum of the suction zone 24a. The transfer suction roll 24 forms in the region of its suction zone 24a a lightly loaded transfer nipple NS upper press roll 20 smooth: **; against the surface and the transfer belt 28A. Above the drying wire 23 is placed an overflow hood 29 which serves to blow hot I *, ', 25 air over the web W.

Although in all the figures above the longitudinal nip zone NP3 is shown as the last third separate nip of the press, the invention may exceptionally be implemented by using a dewatering roll nip N3 in the position of the nip NP3, which is particularly suitable for use in 'with relatively low basis weights and low speed range compared to the use of the long-nip NP3.

tt · * · _ In the invention, the web W has a closed outlet through the entire press section from pick-up 35 to the drying wire 23. In addition, the press, * * tin according to the invention provides good roughness symmetry of web W since both webs 112263 7 mat become pressed alternately against a smooth surface. In the nipples N3, N2, the underside of the web W is against the smooth surface 14 'of the center roll 14 or against the smooth outer surface of the transfer belt 27A, while in the long nip NP3 or similar roll N3 the web W is pressed against the smooth surface 20' of the upper against. In addition, the invention provides a substantially symmetrical drainage through both surfaces of the web W.

The closed press section of the invention is relatively compact and takes up a small amount of space both in the machine direction and in the vertical direction, so that it can usually easily fit in modernizations to replace the old COMBI press or the like. One feature of the press section geometry shown in the figures is that the first roll nip N3 and the separate nip NP3; N3 of the press are at substantially the same height 15 and the second middle roll nip N2 is slightly above the height position of said nipples N3 and NP3. Further, the first and second nipples N3, N2 are substantially opposed on opposite sides of center roll 14.

The claims which follow, within the scope of the inventive concept defined herein, may vary and deviate from the above details by way of example only.

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Claims (9)

A closed press portion of a paper machine comprising a pick-up suction roll (13) and a surrounding this pick-up felt (12), the pick-up suction roll (13) and the pick-up felt ( 12) forms a pick-up location (P) with a forming wire (10) in a forming part of the paper machine and in connection with the pick-up suction roll (13) is arranged a middle roll (14) which forms a first press nip (Ν3). ) with the pick-up suction roll (13) and a second press nip (N2) with a press roll (16), characterized in that the press roll (16) is a press suction roller provided with a suction zone (16a). suppress the web (W) is released from the center roll (14) or from a conveyor belt (27a) running around the center roll (14) and is sucked to the lower surface by a water-absorbing upper tissue (15) arranged to pass through the second nip ( N2) and on whose lower surface the web (W) is conveyed in a closed pull to a lower tissue (17) in the press portion, that the web (W) is carried on the upper surface of said lower web tissue (17) further into a substantially dewatered third press nip (NP3; N3) in the press portion, and the web (W) is conveyed from the latter third press nip (NP3; N3) in a final pull to a drying wire (23) in a drying portion after press section. Press section according to claim 1, characterized by,, ···. that the web (W) in connection with the tip drawing is passed through the entire press section of a dryer cylinder (25) in the drying section, from which the web (W) 25 is guided to a projecting system at the end or in a disturbance situation » · · '* Tion. Press section according to claim 1 or 2, characterized in that the last separate nip in the press section is a longitudinal nip (NP3), the upper roll of which is a press roll (20) and a lower roll of a shoe roll with a:: flexible hose jacket (19b) and a press shoe (19a) at the longitudinal nip zone (NP3). « 4. Press section according to any of claims 1-3, characterized in that the upper roll in the longitudinal nip (NP3), which forms the last nip in the press, is one with a smooth surface (20 '). provided press roll (20); ; in connection with which is formed by means of a suction zone (21a) on a transfer suction roller (21) a lightly loaded transfer nip (NS), with which the web (W) can be transmitted in suction roll transfer (22,22a) from said press roll (20) either directly to the drying wire (23) or to a conductive transfer wire (22) leading to a drying wire (23). 5 Press section according to any of claims 1-4, characterized in that a transfer belt loop (27A) is arranged to run around the center roller (14) in the press, which loop is most preferably substantially non-water-absorbing and has an outer surface. from which the web 10 (W) is transmitted in suction roll transmission on the lower surface of the Upper Press Blanket (15) (Figures 2 and 4). Press section as claimed in any one of claims 1-5, characterized in that the web is transferred from the second Upper press felt 15 (15) in suction roll transfer (18, 18a) on the Upper surface of the lower press felt (17), on which the web (W) is conveyed to the last press nip, most preferably a longitudinal nip (NP3) through which is arranged to run an Upper transfer belt loop, on which the web is passed through the transfer nip (NS) either to the drying wire (23) or to a transfer wire (21), which is to guide the web (W) in the final pull to the drying wire (23). Press section according to any of claims 1-6, characterized in. ···. notwithstanding that the first roll nip (N3) and the different nip * ·. (NP3; N3), most preferably a longitudinal nip (NP3), in the press between themselves has substantially the same height position and the second middle roll nip (N2) is located slightly above the height position of said nip (N3, NP3). ► · · 8. Press section according to any of claims 1-7, characterized in that the first and second nip (N1 (N2) in the press section, which are most suitable bed are dewatering roll nip) are provided with a water: :: receiving press felt (12,15), are located on opposite sides of the center roller (14) substantially opposite each other. 9. Press section according to any of claims 1-7, with which a prior COMBI press is modernized, characterized in that: the components of the first part of the press section are essentially 1 from the old press section, to which is attached the various nip (NP3; N3), most preferably a long nip (NP3), and the tissue loops for obtaining closed tension of the web (W) throughout the entire press section. 5 • · · * »· I * · · · · · · · · · · · t * ·