EP1862589B1 - Method and device for producing a sheet made of paper or cardboard - Google Patents

Abstract

A paper mill (1) has a wet paper production line (2) followed by a drying station (6) followed by a finishing station (6). The paper web is sub-divided into two longitudinal strips either prior to, or within the first third of the drying station. Each longitudinally sub-divided strip is surrendered to a respective glazing station.

Description

The invention relates to a method for producing a web of paper or cardboard, in which the web is guided from a production section through a drying section and then to a further processing device. Furthermore, the invention relates to a device for producing a web of paper or cardboard with a production section for forming the web, a dryer section and a further treatment arrangement behind the dryer section.

In the manufacture of a paper or board web, a fiber suspension is usually applied to a wire, so that when draining the water forms a still very wet web, which must then be dried in a press section and a dryer section. The maximum width of such a web is currently about 10 m. Behind the dryer section, the web can then either satin or wound online. Other treatment steps, such as the application of a stroke, are also possible.

Regardless of whether the web is satin finished online or only after winding, it is necessary to use a calender for the calendering, whose working width is at least as large as the width of the web. This can be realized at the widths of the web used today without major problems.

However, the potential for increasing productivity is limited. The speed at which the web is produced can only be increased to a limited extent. An increase in the width of the web also encounters difficulties. This affects less the press section and the dryer section. Drying cylinders used in the dryer section are designed to transfer heat output rather than deflection behavior. They already have diameters that would not increase the deflection in a broadening to impermissible values.

The problem is more with the calenders. The diameters of the rollers of the calender would have to be increased because of the critical bending speeds and the deflection. This, in turn, has an effect on the height of the necessary line loads, which, with correspondingly larger diameters, would grow into a range which would require much greater dimensions of the uprights. In the case of deflection adjustment rollers, the yoke would have to be dimensioned correspondingly larger in order to be able to compensate for the deflection.

The WO 01/65005 A already discloses a paper machine in which a web is cut into partial webs during production.

The invention has for its object to be able to increase the productivity in producing a web of paper or cardboard.

This object is achieved in a method of the type mentioned above in that the web is divided before or in the first third of the dryer section in the longitudinal direction into two partial webs and cuts behind the dryer section from each sub-web an insertion strip respectively at the outer edges of the sub-webs, guides the lead-in strip along a predetermined path for each sub-web and then cuts each sub-web to width.

Such an approach can greatly increase productivity by allowing the width of the web in the production section to be significantly increased. For example, widths of the order of 12 to 20 m would be readily imaginable. This wide web is then subdivided into a plurality of sub-webs at a relatively early stage of manufacture, with each sub-web then being dried by itself. This in turn has the advantage that a quasi-symmetrical moisture profile results in each partial web. Such a symmetrical moisture profile can not be achieved by dividing the web only at the exit of the dryer section or at a late stage of drying, because the edges of a web generally have a lower moisture content than the center of the web. However, if each partial web completely or at least largely has its own drying process, then dry at each partial web both edges approximately equal, so that the partial webs thus produced largely correspond to the previously generated tracks and you get the knowledge gained so far for the further treatment of the web, especially the calendering the train, can easily transfer to the sub-tracks. To facilitate the handling of the partial webs, you cut on End of the dryer section then from each sub-web an insertion strip, so that it is possible to further treat each sub-web for itself, for example, wind up or satin. As soon as the insertion strip has been guided as later the part track is to run, the part track can be cut to width.

Here you divide the train in two sub-trains. The web is thus halved, so it is advantageous, but not necessary, if the partial webs are the same size. The use of exactly two partial webs especially facilitates the guidance of the partial webs following the dryer section.

It is particularly preferred that one intersects the insertion strips at the outer edges of the partial webs. Thus, it is possible that the guide means, which are used to continue the partial webs following the dryer section, are arranged on the end faces of the further treatment arrangements. In particular, for detecting the insertion strips, this embodiment has advantages.

Preferably, the parting of the web is begun before the insertion strips have passed through the processing device. In order to keep the waste when performing the track small. The web that passes through the dryer section but has not yet been cut into sub-webs must be returned to the pulper because it can not be handled in the then wide width. Accordingly, one can share with start the web after the Einführstreifen can be handled. Once you can handle the Einführstreifen, you have the sub-webs "under control" so that you can then relatively quickly begin to divide the web into the sub-webs.

Preferably, the distance of the partial webs when passing through the dryer section is increased. This has two advantages. On the one hand, it prevents the two partial webs from getting caught or otherwise interfering with one another. On the other hand, the removal of the partial webs and further handling is facilitated by the distance.

Preferably, a screen is used in the generating section and divides the web on the screen. This ensures that the entire dewatering process, ie the dewatering in the press section and the dewatering in the dryer section, runs the same for each partial web, so that asymmetries in the partial webs can be avoided or kept small in the moisture profile.

The object is achieved in a device of the type mentioned above in that in a region from the production section to the first third of the dryer section a longitudinal cutting device for dividing the web is provided in partial webs that behind the dryer section a Einführstreifen-cutting assembly for cutting an insertion of each Part track is arranged and that each guide means for guiding the insertion strip is provided by the further treatment arrangement.

With such a device, one can perform the above-mentioned method. The railway is thus divided into two partial railways at a relatively early stage. The partial webs then run through the dryer section at about the same time but separated from each other, so that the moisture profile in each partial web can be set substantially symmetrically, or at least as known from previous production devices. The guidance of the partial webs at the end of the dryer section is facilitated because the Einführstreifen-cutting assembly is able to provide each sub-web with an insertion strip, which can then be performed separately for each sub-web of the other sub-web.

In this case, two guide means are provided which are each associated with end faces of the further treatment arrangement. On the front pages is usually enough space available to accommodate the management facilities.

Preferably, the further treatment arrangement for two partial webs each have a take-up device, wherein the take-up devices have drives which are arranged at different ends. This is sufficient space available to accommodate the drives of the winders. Preferably the drives are arranged on the respective outer end sides.

It is also advantageous if spreading means are provided behind the longitudinal cutting device. Thus, the partial webs get at the latest when passing through the dryer section a small lateral distance from each other, so that they do not overlap each other or can interfere in any other way.

Fig. 1

eine schematische Darstellung einer Papiermaschine in Draufsicht,

Fig. 2

eine Papierbahn in einem ersten Stadium des Aufführens,

Fig. 3

die Papierbahn in einem weiteren Stadium des Aufführens und

Fig. 4

die Papierbahn unter Produktionsbedingungen.

The invention will be described below with reference to a preferred embodiment in conjunction with the drawings. Herein show:

Fig. 1

a schematic representation of a paper machine in plan view,

Fig. 2

a paper web at a first stage of performance,

Fig. 3

the paper web in another stage of performing and

Fig. 4

the paper web under production conditions.

Fig. 1 shows a highly schematic representation of a paper machine 1, wherein only the elements are shown, which are necessary for the explanation of the invention.

The paper machine 1 has a generating section 2 with a former 3 and a wire section 4. In the former 3, a pulp is applied to a wire, the pulp consisting essentially of water and a small proportion of fibers. When passing through the wire section 4, the water can drain, so that a web of coherent fibers is formed.

This web is further dewatered in a press section 5 and then dried in a dryer section 6 by the application of heat.

In the running direction behind the drying section 6, a further treatment arrangement 7 is provided.

The proportions are not shown to scale here.

Currently the in Fig. 1 Aggregates shown a working width in the range up to an order of about 10 m. Up to such an order of magnitude, the web thus produced can still be handled in full width.

If now the working width of in Fig. 1 Aggregates 2 to 6 shown increases, for example, to 12 to 20 m, the handling of the web is increasingly difficult.

The web is usually transferred in full width from the wire section 4 in the press section 5 and the drying section 6.

After a certain time, the web 10 has passed through the dryer section 6. Behind the drying section 6, the web 10 is then first passed into a pulper 12, because it is basically not manageable in the present there width.

In the region of the wire section 4, a longitudinal cutting device 8 is arranged, which can cut the web 10 into two partial webs 22, 23, as will be explained below.

At the end of the dryer section 6 there is provided an insert strip cutting assembly 13 with two infeed strip cutters 14, 15 which cuts two infeed strips 16, 17 from the web 10. These two insertion strips 16, 17 are arranged at the longitudinal edges of the web 10, so that they can be grasped by guide means 18, 19 and passed through the further treatment arrangement 7.

Once the lead-in strips 16, 17 have reached their "target" so as to be able to exert a pull on the lead-in strips 16, 17, the two lead-strip cutters 14, 15 are moved towards each other, as shown in FIG Fig. 4 shown to widen the insertion strips 16, 17.

At a suitable time, the slitter 8 has been activated. It generates, for example, in the middle of the web 10, a separating cut 20, which the Track 10 divided into two partial webs 21, 22. Basically, this separating cut 20 can be started as soon as the insertion strips 16, 17 can be handled in a controlled manner, in particular with sufficient tension. Conveniently, however, one agrees the longitudinal cutting device 8 and the Einführstreifen-cutting devices 14, 15 from each other so that the partial webs 21, 22 are cut to width, when the longitudinal section 20 enters the region of the Einführstreifen-cutting devices.

How out Fig. 4 can be seen, the partial webs 21, 22 in any case when passing through the dryer section 6 out so that a small distance 23 is formed. Also, this distance 23 is in Fig. 4 not drawn to scale. He is in the order of cm.

The further treatment arrangement has, in the present case, two winding devices 24, 25, for example in the form of pope rollers. Each winding device 24, 25 is provided with a drive 26, 27, wherein the drives 26, 27 are respectively disposed on the outer end side of the winding means 24, 25, so that the two winding means 24, 25 perpendicular to the running direction of the web 10 is relatively close could be. Of course, it is also possible to offset the winding device 24 'relative to the winding device 25 in the running direction of the web something, so that the two winding means 24', 25 do not collide. Also an offset in height direction is possible.

With the described procedure to produce two practically identical partial webs, because each sub-web 21, 22 also on the side of the distance 23 has an inner edge, which, like the other outer edge also, is dried.

Due to the increased width of the web, the paper machine 1 can run at the same speed or even slower, even with higher productivity, than paper machines known today. For offline calenders, which can travel at relatively high speeds, this presumably means that only two or at most three calenders are required, although virtually two paper webs, namely the partial webs 21, 22, are produced in parallel.

Of course, the same procedure can also be used with a board machine. Here, the board web is then also divided in the area of the wire section 4 or shortly after, so that in turn partial webs are formed, which are dried parallel to each other.

Claims (8)

1. Method for producing a web of paper or board, in which the web from a production section is led through a drying section and after that to a further processing device, the web being divided in the longitudinal direction into two part webs (21, 22) before or in the first third of the drying section (6) and, after the drying section (6), a tail (16, 17) being cut from each part web, in each case at the outer edges of the part webs (21, 22), the tail being led along a predetermined path for each part web and each part web then being cut to width.
2. Method according to Claim 1, characterized in that the dividing of the web is begun before the tails (16, 17) have passed through the processing device.
3. Method according to one of Claims 1 to 2, characterized in that the distance between the part webs (21, 22) is increased during the passage through the drying section (6).
4. Method according to one of Claims 1 to 3, characterized in that a wire is used in the production section and the web is divided on the wire.
5. Apparatus for producing a web of paper or board, having a production section for forming the web, a drying section and a further treatment arrangement after the drying section (6), a longitudinal cutting device (8) for dividing the web (10) into part webs (21, 22) being provided in a region from the production section as far as the first third of the drying section, a tail cutting arrangement (13) for cutting a tail (16, 17) from each part web (21, 22) being arranged after the drying section (6), and in each case a guide device (18, 19) for guiding the tail (16, 17) through the further treatment arrangement (7) being provided.
6. Apparatus according to Claim 5, characterized in that two guide devices (18, 19) are provided, which are each assigned to ends of the further treatment arrangement (7).
7. Apparatus according to Claim 5 or 6, characterized in that the further treatment arrangement (7) for two part webs (21, 22) in each case has a winder (24, 24' 25), the winders (24, 24', 25) having drives (26, 27) which are arranged at different ends.
8. Apparatus according to one of Claims 5 to 7, characterized in that spreading means are provided downstream of the longitudinal cutting device (8).

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