EP0652992B2 - Press of paper machine for thin papers - Google Patents

Abstract

PCT No. PCT/EP94/01730 Sec. 371 Date Jan. 30, 1995 Sec. 102(e) Date Jan. 30, 1995 PCT Filed May 27, 1994 PCT Pub. No. WO94/28240 PCT Pub. Date Dec. 8, 1994The press section of a paper machine for thin papers has the following characteristics: a pressing gap is formed by a rotary, smooth surface (1) in contact with the paper and by a felted pressing roll (3); the smooth surface (1) transfers the paper web downstream of the pressing gap to a heatable roll (4) without free pulling of the paper web. The invention is characterized in that the smooth surface (1) is the outer surface of a tubular roll with dimensionally stiff roll sleeve.

Description

The invention relates to a press section of a paper machine for thin Papers according to the preamble of claim 1, in particular for single-sided papers or tissue, in particular those Web acceptance at the last press unit.

Press units in paper machines where the water is one-sided dissipated are well known. For example, the font "Wochenblatt für Papierfabrikation 5 (1988)", page 173 ff. It will there after the press nip the web in free train from the smooth roller decreased by e.g. a smoothing press, a drying cylinder or one Row dryer section to be fed.

The disadvantage of these embodiments is that special transfer elements for the Web are necessary and the frequency of demolition is relatively high.

Furthermore, after the priority date of the present application and thus not German state of the art Patent application DE 42 24 730 C1 referred to in the figure 8 a decrease the paper web from a roller through a press hose Long nip press 13.3 is shown. The disadvantage here is that the service life of the Press hose through contact with the hot surface of the following Cylinder 20 is greatly reduced.

It is an object of the invention to present a press unit in the such transfer elements can be dispensed with, whereby the Tear frequency of the paper web is reduced and at the same time Cost savings through reduced operating costs.

The object is achieved by the characterizing features of claim 1 solved.

• Die heizbare Walze (z.B ein Trocken oder Glättzylinder), an die die Papierbahn von der Rohr-Preßwalze überführt wird, kommt weder mit einem Filz, noch mit einem "Preßschlauch" oder "Preßmantel" in Kontakt.
• Der Filz muß nur einen einzigen Preßspalt durchlaufen.
• Daraus ergibt sich eine höhere Lebensdauer sowohl für den Preßmantel als auch den Filz.

This has the following advantages:

• The heatable roll (for example a drying or smoothing cylinder) to which the paper web is transferred from the tube press roll does not come into contact with either a felt or a "press hose" or "press jacket".
• The felt only has to pass through a single press nip.
• This results in a longer service life for both the press jacket and the felt.

According to the idea of the invention, the following are possible Embodiments of a press section for preferably thin papers, especially tissue paper:

First, a press nip is provided, which consists of a circumferential, smooth surface in contact with the paper and is formed from a felted press roll, the smooth surface transfers the, avoiding a free paper pull Paper web behind the press nip to a heatable roller, the smooth one Surface as the outer surface of a tubular roller with a rigid roller jacket is trained.

It is advantageous if the felted press roll has an extended nip or Shoe press roller is.

Furthermore, it is particularly advantageous if, in the case of such a design Press section the smooth tube roll in front of the press nip with another felted press roll a further, preceding press nip (pre-press nip) forms. Here it is also advantageous if one for each press nip separate, endless felt is provided; however, a single felt can also be advantageous for both press nips due to the operating circumstances. Especially It can be advantageous with regard to the drying performance, even if the further one felted press roll is a shoe or extended-nip press roll.

It can also be advantageous if the further felted press roll is a Is suction roll, the suction zone is mainly in front of the pre-press nip.

In the illustrated embodiments, it may also be advantageous to design the smooth tube roller as a deflection adjusting roller in order to maintain uniform line pressures and thus improve web transfer.
A further advantageous embodiment of the press section results if the heatable roller is a non-felted tube roller guiding the web, which delivers the web to a drying cylinder, preferably avoiding the free paper draw.

In the embodiments shown, it can also be advantageous prove if the gap between the smooth tube roller and the heatable roller, in particular a drying cylinder, can be opened to to facilitate starting without paper.

Figuren 1 bis 7 zeigen Ausführungsvarianten einer Bahnübergabe zwischen der Presseneinheit und der nachfolgenden Papiermaschine mit glatten Walzen.

The invention is explained in more detail with reference to the drawings. It also shows the following:

Figures 1 to 7 show design variants of a web transfer between the press unit and the subsequent paper machine with smooth rollers.

Figure 1 shows the last press unit of a paper machine with a smooth Central roller 1 (a tube roller - i.e. with a rigid outer jacket), with another roller 2 a penultimate press nip together with a passes through single felt. The roller 2 can be a suction roller or be a blind drilled roller. The paper web then remains on the lie smooth roller 1 and is guided to a last press nip which by the roller 1 and an extended-nip press 3 are formed. After that the remains Paper web continues to lie on the smooth roller 1 and becomes a large one Smoothing cylinder 4, which can also be designed as a tissue cylinder, transferred according to the invention.

Figure 2 shows an arrangement similar to Figure 1, but is the last Press nip between the central roller 1, which is also a tube roller is formed, and the counter roll 3 not as an extended nip press but as so-called smoothing press executed. The paper web also remains as in Figure 2 after the last nip on the smooth central roller 1 and is then transferred to a heated cylinder 4, for example. Alternatively, there is also the possibility of the paper web from cylinder 4 passed on directly to a subsequent smoothing cylinder.

FIG. 3 shows a special embodiment of the transfer according to the invention. The beginning of a paper machine is shown here, in which stock suspension is injected between a screen 6 and a felt 10, which abut a blow roller 20, via a headbox 11. The paper web is transported lying on this felt up to the press nip, which is formed here by an extended nip press 3 and the smooth tube roll 1 according to the invention. Possible devices between the press nip and the headbox are not shown here. After the last press nip, the paper web is transferred directly to a subsequent cylinder 5 via the smooth roller 1. The roller 1 can preferably be designed as a deflection adjusting roller in order to ensure a pressure which is as uniform as possible, in particular on the following cylinder 5.
Figure 4 shows a situation at the last press nip of a press section. A press unit between two cylinders 1 and 3 is shown here, the cylinder 1 representing the smooth cylinder according to the invention with a dimensionally stable surface. The two cylinders 1 and 3 are provided here according to the invention on a movable lever arm 40, so that they can be moved in and out in their entirety by the subsequent large cylinder 30 without the press nip between the two cylinders 1 and 3 changing.

Figure 5 shows a further variant of the invention. It's coming from the left a felt 10 carrying a paper web 100 is shown. The felt 10 leads the Paper web from above over a cylinder 300, the one with the following smooth tube roll 1 according to the invention forms a penultimate press nip. While after the penultimate press nip the paper web goes directly to the last one Press nip between the smooth tube roll 1 and the subsequent roll 600 is guided, the felt runs over a conditioning device 8 and Deflection roller 400 separated from the paper web back to the last one Press nip over the roller 600 and is returned from there during the Paper web remains on the smooth roller 1 and directly to the subsequent drying cylinder 7 is passed.

Figure 6 shows a press unit according to the invention of a compact design. It is here 11 stock suspension between a felt and a headbox introduced a smooth tube roller 1. One lies on the smooth tube roller 1 Long nip press 3 and then again on the smooth roller next smooth roller 1 ', the paper web to the subsequent station of the Convicted paper machine.

FIG. 7 shows the arrangement according to the invention using the example of a Paper machine for the production of crepe paper. It's from the right coming tape 500 to see on which the paper web is guided. The The tape is passed together with the paper web over a suction roll 200, which passes the paper web to a profile roller 1 with a rigid jacket. While the belt 500 is being fed back via a deflection roller, the paper web remains on the profile roller 1 and becomes a press nip, formed by the profile roller 1 and an extended nip press 3, supplied by where it remains on the surface of the profile roller and then on a crepe cylinder 4 is transferred, which rests on the profile roller 1.

Claims (10)

1. Press section for a papermachine for thin papers, with the following features:

   1.1 a press nip is provided which is formed by a last press unit and which is formed by a revolving, smooth surface in contact with the paper and a felted press roll (3, 600);
   characterized in that

   1.2 the smooth surface transfers the paper web (100) downstream of the press nip to a heated roll (4, 5, 7, 30, 1'), avoiding a free paper draw, and in that

   1.3 the smooth surface is the outer surface of a tubular roll with a dimensionally stable roll cover (1).
2. Press section according to Claim 1, characterized in that the felted press roll (3) is an extended-nip press roll or a shoe-press roll.
3. Press section according to Claims 1 and 2, characterized in that the smooth tubular roll (1) upstream of the press nip forms, with a further, felted press roll (2, 200, 300), a further pre-press nip located upstream of the press nip from feature 1.1.
4. Press section according to Claim 3, characterized in that a separate, endless felt is provided for each of the two press nips.
5. Press section according to either of Claims 3 and 4, characterized in that the further felted press roll is a shoe-press roll or an extended-nip press roll.
6. Press section according to Claim 3, characterized in that in each case a single, common felt (10) is provided for both press nips.
7. Press section according to one of Claims 3, 4 or 6, characterized that the further felted press roll (200) is a suction roll, whose suction zone is located predominantly upstream of the pre-press nip.
8. Press section according to one of Claims 1 - 7, characterized in that the smooth tubular roll (1) is a controlled deflection roll.
9. Press section according to one of Claims 1 - 8, characterized in that the heated roll (4) is an unfelted tubular roll which guides the web and transfers the web to a drying cylinder, preferably avoiding a free paper draw.
10. Press section according to one of Claims 1 - 9, characterized in that the nip between the smooth tubular roll (1) and the heated roll (30), in particular of a drying cylinder, can be opened.

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