EP0195807A1

EP0195807A1 - Headbox system for a paper machine.

Info

Publication number: EP0195807A1
Application number: EP85904806A
Authority: EP
Inventors: Elmer Weisshuhn; Alfred Bubik; Hans Dahl; Herbert Holik; Rudiger Kurtz; Anton Zembrot; Wolf-Gunter Stotz; Werner Seider; Robert Trondle
Original assignee: Sulzer Escher Wyss GmbH; Escher Wyss GmbH
Current assignee: Sulzer Escher Wyss GmbH
Priority date: 1984-09-19
Filing date: 1985-09-16
Publication date: 1986-10-01
Anticipated expiration: 2005-09-16
Also published as: EP0195807B2; EP0195807B1; DE3514554A1; FI861944A; WO1986001844A1; FI90359B; FI861944A0; US4888094A; US4898643A; DE3514554C3; DE3514554C2; US4897158A

Abstract

Dans un système de caisse de tête pour une machine à papier, caractérisé par une distribution réglable de la pâte sur la largeur de la bande, le passage de la pâte dans l'écartement des rouleaux de sortie (8) est commandé de manière que la distribution des fibres sur la largeur de la bande ait également un profil voulu en ce qui concerne l'orientation et la quantité des fibres. A cet effet, l'écoulement de la pâte est commandé de façon à ce qu'en cas de changement de la distribution de la pâte sur la largeur de la bande, la composante horizontale de la direction d'écoulement dans l'écartement de sortie reste, à tout moment, et en tout endroit, orientée dans la direction de la machine, ce qui permet d'éviter tout écoulement transversal et d'obtenir un profil prédéterminé dans l'écartement de sortie (8).In a headbox system for a papermaking machine, characterized by an adjustable distribution of the pulp over the width of the web, the passage of the pulp through the spacing of the exit rollers (8) is controlled so that the The distribution of fibers across the width of the web also has a desired profile with respect to the orientation and quantity of fibers. For this purpose, the flow of the dough is controlled so that when there is a change in the distribution of the dough over the width of the strip, the horizontal component of the flow direction in the outlet gap remains, at all times and in all places, oriented in the direction of the machine, which makes it possible to avoid any transverse flow and to obtain a predetermined profile in the outlet gap (8).

Description

Headbox device for a paper machine and method for its operation

Technical field

The invention relates to a headbox device for a paper machine with a distribution box for distributing a stock suspension supplied over the web width of the paper machine, a guide device for the stock suspension having a plurality of holes or channels and a subsequent nozzle space with an outlet gap for distributing the stock suspension with a specific one Weight per unit area over the web width of the paper machine, the mass distribution over the web width of the paper machine optionally being changeable by locally changing the width of the outlet gap and / or by locally changing the consistency, and a method for operating such a device. State of the art

Such headbox devices are known, for example, from US Pat. No. 4,087,321. They are used to feed a prepared pulp suspension to a paper machine and to distribute it over its entire web width in a certain way. This distribution of the material suspension should take place in such a way that the paper web produced with the paper machine has certain properties over the web width, with usually a uniform weight per unit area (mass per unit area) after drying, a uniform moisture content, and a uniform fiber orientation over the entire web width is sought.

From US Pat. No. 3,556,935 or US Pat. No. 4,089,739 it is known to design the width of the outlet gap of the nozzle space to be adjustable by means of a plurality of adjusting devices distributed over the web width. With this, the amount of material suspension can be determined via the

Control web width, but not fiber orientation.

Inadequacies in the construction of the paper machine, as well as physical processes during the paper manufacturing process, are the reason why not all of the desired properties across the web width are usually the same as desired or even. For example, defects in the wire section or the shrinkage of the paper web during drying, in particular at the web edge, are compensated for by changes in the local mass flow, as are deficiencies in the geometry of the distributor Guide device or the nozzle space. In order to change or set a certain local mass flow, the width of the outlet gap from the nozzle space is often changed locally. However, this also locally changes the pressure in the nozzle area and the pressure curve in the fiber suspension over the machine width is uneven. These local pressure differences in the nozzle area lead to transverse flows in the nozzle area, which have an effect right up to the outlet gap, in such a way that the direction of the flow in the nozzle area, seen across the width, is not exactly parallel and corresponds to the machine direction. Even small deviations from the machine direction lead to undesirable nonuniformity in the fiber orientation of the paper web produced across the web width because of the transverse components of the speed vector which exist when the suspension beam emerges.

From AT-363 776 it is already known to compensate for pressure differences in the flowing stock suspension in the distributor over the web width in that the stock suspension is additionally fed or withdrawn stock suspension at suitable points, for example in the distribution box, so that the pressure curve in the distribution box is constant over the entire web width. However, this measure alone cannot compensate for all pressure differences in the nozzle area.

From US-3,573,160 it is known to increase the speed profile of the stock suspension over the web width Measure and adjust the cross-section of the distributor accordingly, eg using an adjustable wall, in order to achieve a uniform speed of the suspension in the outlet gap. This also means that pressure differences and cross flows can only be prevented incompletely.

As described in GB-1 216 114, attempts have also already been made to achieve a uniform flow of material through a plurality of individually adjustable overflow tubes on the distribution box, whereby the disadvantages mentioned cannot be avoided either.

For example, in the nozzle area at the edges due to friction losses on the side walls

- Additional pressure losses, which have the effect that the pressure in the nozzle chamber and the flow of material through it drop towards the edge. This also causes cross currents in the nozzle area, with the result that the flow threads are no longer aligned exactly parallel in the machine direction.

In DE-A-2 151 906 it is proposed to achieve a uniform speed and quantity of material also in the edge area by providing a gap on the distributor which can be individually adjusted over the width. Differences in pressure and cross flows in the outlet gap are also present here.

Even in the case of a plurality of rows of bores or channels which are offset with respect to one another in the guide device, as disclosed, for example, in US Pat. No. 4,137,124, nonuniformities, such as lower material flows per unit of width, which likewise lead to pressure differences and to cross flows in the nozzle space and at the gap. This could be compensated for by supplying additional material suspension or water on the sides through the side walls of the nozzle space, but this entails considerable mechanical and control expenditure.

The invention sets itself the task of eliminating the above-mentioned disadvantages of the prior art and, in particular, of creating a headbox device for a paper machine and a method for operating it, with which, despite the transverse profiles desired for setting, of the basis weight necessary change of the local mass flow reaches a flow state in the nozzle space and at the outlet gap which is free of cross flows. A paper web produced in this way should have a uniform fiber orientation across the web width.

Presentation of the invention

These tasks are solved with the device according to the invention in that, even when the mass distribution is changed, the flow of the stock suspension in the nozzle space can be adjusted at the same time so that the horizontal component of the flow direction of the stock suspension is seen across the web width of the paper machine is parallel everywhere in the machine direction at the outlet gap and the flow velocity in the outlet gap, seen across the machine width, corresponds to a given profile. This can be done, for example, either by changing the pressure profile in the distributor, by changing the geometric dimensions of the distributor, the guide device or the nozzle space, or by supplying or removing material suspension or supplying water in the distributor in the Guide device or in the nozzle room, individually or in combination with one another.

These setting options ensure that the flow in the outlet gap is influenced in such a way that when the mass distribution is set to a desired cross profile, there are still no cross flows, and thus a paper with the desired mass distribution and with the desired, e.g. uniform fiber distribution with regard to quantity and orientation over the web width is obtained.

The method according to the invention for operating such a device is characterized in that when the mass distribution of the stock suspension is changed over the web width of the paper machine by local change in the width of the outlet gap and / or by local change in stock density, the flow at the same time the. The stock suspension in the headbox is adjusted such that it is seen across the web width of the paper machine, the horizontal component of the flow direction of the stock suspension at the outlet gap is parallel everywhere in the machine direction, and the flow speed in the outlet gap, seen across the machine width, corresponds to a predetermined profile , for example, is at least approximately the same. This can be done, for example, either by changing the print profile in the distribution box, by changing the geometry of the distribution box, the guide device or the nozzle space or by supplying or removing material suspension or supplying water in the distributor, in the guide device or in the nozzle space, individually or in combination with each other.

Brief description of the drawings

The invention, as well as advantageous developments of the same, are explained in more detail with reference to the exemplary embodiments shown in the figures.

FIG. 1 shows a headbox device in plan view.

FIGS. 2-4 show different designs of distribution boxes with an adjustable pressure curve in two vertical sections,

FIG. 5 shows a headbox device in a vertical section,

FIG. 6 shows a headbox device with various possible addition or removal points for stock suspension or addition points for water,

FIGS. 7 and 8 show guide devices with different geometries over the web width, Figures 9-11 show different arrangements of feed lines and branches on a headbox.

Description of exemplary embodiments of the invention

The headbox device shown in FIG. 1 has a distribution box 1, the cross section of which is reduced in the direction of flow F of the stock suspension. The substance suspension is e.g. to understand a mixture of fibers with additives for paper or cardboard manufacture, but also filler suspensions for paper coating. At the end of the distributor with the larger cross section, a connecting pipe 2 is connected to feed the stock suspension, and the other, opposite

End with ^'the smaller cross section a return line 3. The distributor preferably has an approximately - conical shape or may be formed as a truncated pyramid.

A guide device 5 is connected to a longitudinal side 4 of the distributor 1. In principle, this can be designed as any guiding device customary in paper machine technology, for example, as shown in detail in the figure, as a step diffuser with gradually expanding parallel channels 6, e.g. according to CH 518 406 (US 3 725 197).

At the exit of these channels 6 there is a nozzle chamber 29 with an outlet gap 8, this being formed by two lips 7 or by a lip and one mounted on the lip, but opposite it freely movable aperture. The stock suspension now reaches the wire section of the paper machine via the channels 6, the nozzle chamber 29 and the outlet gap 8.

At least one of the lips 7 or an aperture attached to it is provided with a plurality of adjusting devices 30 distributed over the width, with which the gap width can be adjusted individually over the width manually or by means of a control device in order to use the gap 8 flowing material suspension flow a desired oven-dry basis weight profile of the paper web thus produced across the width. If, however, the gap width is changed locally via adjusting devices 30 at the outlet gap 8, the local flow conditions, such as pressure and speed in the nozzle space, also change in addition to the local mass flow and the basis weight profile. The result of the pressure differences are transverse flows in the nozzle space, which are present up to the outlet gap 8 and act on the fiber storage on the wire of the paper machine until the entire fiber structure is fixed in the sheet. Because of the different cross currents across the web width of the machine, there is then a different fiber storage in the sheet over the web width. To such

To prevent cross-flows of the material suspension, certain precautions are necessary. One of these possibilities is to readjust or readjust the pressure of the stock suspension over the web width of the paper machine or the width of the nozzle space while maintaining the set gap width profile. On the other hand, the gap width can also be constant are held and instead the material density is changed locally so that the desired cross profile, for example the oven-dry basis weight, arises in the paper web at constant pressure across the width. For this purpose, it is necessary to add or remove material suspension or water at suitable points, individually distributed over the width.

Similar to gap width adjustments, another phenomenon has an effect that arises from the fact that at the edges of the paper machine, as a result of frictional losses on the side walls 9, there is also a pressure loss in the stock suspension. Instead of compensating for this pressure loss by supplying suspension or water through the side walls 9 via additional lines 10, which means considerable mechanical and control expenditure, the necessary compensation can be carried out in a simpler and more precise manner by the same pressure regulation or material. density control or by the same change in the geometry as is necessary to maintain a certain basis weight profile with uniform fiber orientation. In the same way, the shrinkage occurring at the edges during the drying of paper webs can also be compensated for, so that a paper web is produced which is uniform over the entire web width.

Pressure compensation can be carried out individually or in combination with one another using various measures. One possibility for pressure compensation over the web width of the machine is that as in FIG 1, a plurality of branches, which are designed as branch lines 11, 12, 13 and 14 and are connected to the interior of the distributor 1, are connected to one longitudinal side of the distribution box 1 and distributed over its length. Controllable valves 15, 16, 17, 18, 19 are provided in these branch lines, by means of which the flow rate of the branch lines and the return line can be changed. The branch lines 11, 12, 13 and 14 and the return line 3 are connected, for example, to a common collecting line 20. The stock suspension branched off at the individual connection points of the branch lines and via the return line can be discharged via this. Depending on the amount of suspension removed in the individual branch lines, the hydrostatic pressure profile in the distributor 1 changes from the location of the connection of the relevant branch lines. The extent of the pressure change can be adjusted by means of the valves 15, 16, 17, 18 and 19, so that by actuating these valves it is possible to set the required pressure curve over the length of the distributor or the width of the paper machine. Due to the shape of the distributor 1, a certain pressure course in the distributor can initially be roughly predefined, so that only the remaining deviations have to be corrected by the actuation of the valves.

The pressure setting at the various setting points can either be done manually, by means of a visual pressure indicator or after observing the paper web produced, or according to the measurement results for certain paper properties, using suitable sensors were determined over the width of the paper web, for example the basis weight or the fiber orientation, or, as indicated in FIG. 1, with the aid of a control device 26 connected to the various measuring devices. Along the direction of flow F on the distributor 1 pressure measuring devices 21, 22, 23, 24 and 25 are provided, with which the hydrostatic pressure of the suspension in the distributor 1 or its course in the longitudinal direction is determined. In principle, such pressure measuring devices can be designed and arranged as desired, and the pressure measurement can also take place in the nozzle area. In the simplest case, the measuring devices can be assigned to the individual valves and control them directly, or the measuring devices can, independently of the valves, feed their measured values to the control device 26, which controls and adjusts the individual valves in a suitable manner, for example by means of a process computer until the desired pressure prevails at all measuring points.

The pressure profile predetermined by the control device 26 can be selected so that the pressure shows a desired course, for example is kept constant over the entire width, or certain edge corrections can be included, for example a somewhat higher pressure at both edges to compensate for pressure drops on the side walls. In addition, the control device 26 can also be controlled by further sensors, not shown, which, for example, determine the thickness, the basis weight, the curl (curl) or the fiber orientation of the paper produced. determine or measure along the width of the paper web and deliver corresponding additional control signals 28 by means of which an additional pressure correction can be carried out or a pressure profile can be specified. If suitable operating personnel are available, however, such a control can also be carried out in a simpler manner manually or semi-automatically by observing the measured values of the individual measuring devices and corresponding readjustment. Such a simple control is often sufficient, since a one-off adjustment after starting up a paper machine is usually sufficient and readjustment is only necessary if operating parameters, such as the pressure or the composition of the stock suspension, or if the production changes is changed, for example if the machine is changed over to a different type of stock suspension, which results in a change in the pressure distribution. With known headbox devices, this was only possible with difficulties and complications.

The cross section of the branch lines 11, 12, 13 and 14 can be different, depending on the necessary correction. Likewise, the mutual distance between these branch lines can be selected differently. However, it is also readily possible to provide lines of the same diameter at the same distance from one another, in a number that ensures the necessary controllability.

Instead of discharging part of the stock suspension via the branch lines, the branch lines can also serve to supply additional material suspension. In this case, a feed line must be provided instead of a return line 20. This can be connected to the supply line 2 which is present in any case, or else to a supply separate from it, the devices for the flow control 15, 16, 17, 18, 19 being designed as suitable, controllable pumps. If necessary, however, only a part of the branches can be used to remove pulp suspension, while the other branches can supply pulp suspension. The

Control elements can be designed so that the flow direction and the flow rate can be controlled.

FIG. 2 shows a variant in two vertical sections, in which the distribution box 1 is connected to a collecting container 20 via connecting lines 11-14. The height of the end of the connecting lines 11, 12, 13, 14, which goes into the collecting container 20, is adjustable, for example by sleeves 66 which can be displaced from the outside or by a telescopic design of the connecting lines which extends over at least part of the connecting lines . This creates a weir that is adjustable in height and thus makes the local pressure in the distributor individually adjustable.

FIG. 3 shows a modification in which the connecting lines 11, 12, 13 are designed as slots with adjustable surface elements 60, 61 and 62 behind them, which serve as overflow weirs. By adjusting these surface elements, the effective weir height can be changed locally, so that here too a local pressure correction takes place in the distribution box 1. Another possibility for influencing the pressure conditions is shown in FIG. 4, in which the material is drawn off not via individual branch lines arranged over the machine width, but via an outlet slot 64 between the distribution box 1 and the collecting container 20, the outlet slot 64 via the entire machine width goes. A vertical overflow weir 63 extending over the entire width is also provided in the collecting container 20, the height of which can be adjusted locally from the outside over the width. As a result, the hydrostatic pressure in the distributor or in the nozzle can be changed simply by changing the weir height of the outlet slot 64. Instead of a vertical weir, a displaceable screen 65 can also be provided, by means of which the outlet slot 64 can be individually adjusted over the width.

Instead of attaching the branch lines or connecting slots to the side of the distribution box 1, these can also be provided at other points of the headbox device, for example on the diffuser block 5, or in the nozzle chamber 29 immediately after the diffuser block or just before the outlet gap 8 or in between.

FIG. 5 shows an analog headbox device in vertical section, in which again a distributor 1, a diffuser 5 with a row of parallel channels 6, and a nozzle chamber 29 with an outlet gap 8 are provided. The stock suspension flows from the nozzle space 29 onto the sieve guided over a breast roller 31 32 a paper machine. The front part 33 of the upper delimitation lip 7 of the nozzle space 29 can be individually adjusted over the width by means of a joint 34 and by means of adjusting device 35 distributed over the width of the outlet gap 8. In many cases, the outlet gap is delimited at the top by a diaphragm which is mounted on the upper lip, but is freely movable to a certain extent with respect to the upper lip. The gap width can then be changed using the adjustment devices attached to the cover. As a result, the amount of suspension emerging from the gap can be controlled locally independently over the width. The supply or discharge of fiber suspension is again carried out via branch lines 11 on the distributor 1 and also or optionally via branch lines 51 on the nozzle chamber 29, valves or pumps 36 or the designs shown in FIGS. 2-4 being provided for quantity regulation.

As shown in FIG. 6, further possibilities are that the branch lines are provided either selectively or in combination on the distributor 1, on the diffuser block 5 or on the nozzle chamber 29. Changes in the pressure curve can be compensated for as close as possible to the point of origin. In the example shown, the possibility is provided to provide branch lines 37 on the upper side of the distributor 1 or at another location. Instead, the branch lines can also be led directly out of the diffuser block 5. In the example shown, lines 39 are, for example, direct in the first diffuser stage, lines 40 in the second diffuser stage after the paragraph to the first stage, or lines 41 into the third diffuser stage immediately after the paragraph to the second stage. However, feed lines can also be provided in the nozzle space 29 itself, for example lines 42 in the beginning of the nozzle space, immediately behind the outlet openings 43 from the diffuser channels or lines 44 which are movable in the vicinity of the outlet gap 8 of the nozzle space 29 Part 33 of the upper lip opens out. As already mentioned, these lines can, depending on requirements, lead to

For the purpose of pressure regulation or the change in consistency of water or white water with a lower consistency or suspension of material are added or removed.

A further pressure regulation possibility in the distributor 1 can be created by changing the distributor ratio, e.g. through a movably formed rear wall 45 of the distributor. The mobility can be achieved in that the rear wall 45 can be adjusted either manually or by means of a control device over the width of the distribution box, as a result of which the pressure profile in the distributor can be adjusted, or in that the rear wall 45 is designed as a flexible and deformable membrane, which adjusts itself automatically, for example with the aid of a pressure cushion on the back, so that the same pressure prevails over the entire width of the distribution box.

In combination with other adjustment and control options or alone, you can achieve the same

Flow velocities and the same pressures across the width of the nozzle area change the nozzle geo- be necessary. For this purpose, adjustment options 52 are necessary, which are to be provided immediately after the guide device, in front of the outlet gap or also in between, wherein the adjusting devices can also be attached at two or more positions in the machine direction.

Further control options consist in providing adjustable orifices 46 in front of the inlet openings 38 of the diffuser channels 6 or corresponding adjustable orifices 47 in front of the outlet openings 43 of the diffuser channels. These can consist of displaceable elements, iris diaphragms, inflatable bodies or other elements. Suspension or water can also be supplied via lines 50 directly at the inlet 38 of the channels, or the channels can be narrowed by controllable pressure bodies 27.

The increased pressure loss at the edges, e.g. due to friction on the side walls 9, it can be compensated that the pressure loss of the guide device changes in the edge zones, e.g. is reduced, which is achieved by changing the passage cross section per unit width.

FIG. 7 shows an example of a diffuser block 5 with a plurality of rows of step diffusers arranged one above the other. To reduce the pressure loss of the diffusers, the cross section of the diffusers in the edge zone 48 on the side wall 9 is larger than in the adjoining central zone 49, so that the pressure loss in the material Suspension in the edge zone is somewhat smaller than in the middle and thus the increased pressure losses in the edge zone can be compensated.

In the case of the diffuser block 5 shown in FIG. 8, the individual rows of step diffusers are offset from one another, which means that a lower nozzle pressure arises in the edge zone 48 due to the diffusers missing relative to the center 49. A larger material flow per unit of width is achieved in the edge zone by making additional bores or by reducing the pressure loss of the individual element of the guide device in the edge area, so that a pressure correction is also possible here. In this way, fundamental deficiencies in the design of the distributor or at another location on the paper machine can also be compensated for by changing and adapting the hole diameter or pressure loss across the web width.

Modifications and appropriate further developments are possible and are within the scope of the inventive concept. Thus, as shown in FIG. 9, the branch lines 11 connected to the collecting line 20 can advantageously also be connected at the highest point of the distributor 1, which ensures that any air excretions can be safely removed. Immediately next to it, the connection for the diffuser 5 can be provided, so that the pressure control takes place in the immediate vicinity of the inlet of the diffuser. The collecting line can also be guided directly along the distributor 1, so that the branches 11 are formed by openings which connect the distributor 1 and the collecting line 20.

FIG. 10 shows an example in which the diffuser is designed as a guide device which is known per se and which connects a distributor 1 with the lips 7 and an outlet gap 8 and has two pipe systems connected in series and separated by a space 55 bypassing the suspension 53 and 54. This intermediate space 55 is connected through branch openings 56 with an independently controllable or regulable cross section to an overflow line 57, which at the same time shows a damping effect.

FIG. 11 shows an analogous example in which the controllability is achieved by sliders 58 which change the cross section of the branch openings. The openings 59 can optionally also be brought forward to the beginning of the nozzle chamber 29.

Claims

1. Headbox device for a paper machine with a distribution box (1) for distributing a supplied material suspension over the web width of the paper machine, a guide device (5) having a plurality of holes or channels (6) for the material suspension, and a subsequent nozzle space (29) with an outlet gap (8) for distributing the material suspension with a specific weight per unit area over the web width of the paper machine, the mass distribution over the web width of the paper machine optionally by locally changing the width (h) of the outlet gap (8) and / or can be changed by changing the material density locally, characterized in that, even if the mass distribution changes, the flow of the material suspension in the headbox can be adjusted such that, seen across the web width of the paper machine, the horizontal component of the flow direction of the material suspension at the outlet gap (8) everywhere l is parallel in the machine direction and the flow velocity in the outlet gap (8), via the machine seen broad, corresponds to a predetermined profile.

2. Device according to claim 1, characterized in that in the area of the entry into the nozzle chamber (29) and in the area of the outlet gap (8) there are the same speeds and pressures across the machine width.

3. Device according to claim 1, characterized in that at individual points in the nozzle chamber (29) seen in the machine direction, or over the entire length of the nozzle chamber (29), the same speeds and pressures are present across the machine width.

4. Device according to one of claims 1-3, characterized in that the flow of the stock suspension either by changing the pressure profile in the distributor (1), by changing the geometric dimensions of the distributor (1), the guide device (5) or Nozzle chamber (29), or by supplying or removing material suspension, or supplying water in the distributor (1), in the guide device (5), or in the nozzle chamber (29), individually or in combination with one another.

5. The device according to claim 4, characterized gekenn¬ characterized in that distributed over the width of the headbox, controllable branches (11 - 14, 37, 39 - 42, 44, 56, 58, 59) for controlling the Pressure in the stock suspension and / or the stock suspension amount are provided.

6. The device according to claim 5, characterized gekenn¬ characterized in that the branches (11 - 14, 37) are connected to the distribution box (1).

7. The device according to claim 6, characterized gekenn¬ characterized in that the branches (11) at the highest point of the distribution box (1) are connected.

8. The device according to claim 6, characterized in that the branches (11) in the immediate vicinity of the inlet openings of the guide device (5) are connected to the distribution box (1).

9. Device according to one of claims 6-8, characterized in that the branches (11

- 14) protrude with its end facing away from the distribution box (1) into a collecting container (20), the length of its part projecting into the collecting container (20) being variable.

10. Device according to one of claims 6-8, characterized in that the branches (11

- 14, 64) are formed as at least one opening and that an overflow weir (60, 61, 62) which is adjustable in height is provided at the openings in the collecting container (20).

11. The device according to any one of claims 6-8, characterized in that the branches consist of a slot (64) extending in the longitudinal direction between the distribution box (1) and a collecting container (20), the width of which can be adjusted locally.

12. The apparatus according to claim 5, characterized gekenn¬ characterized in that the branches (39 - 41, 56, 58) are connected to the guide device (5, 55).

13. The apparatus according to claim 12, characterized in that the branches (39) are connected to the first stage of a channel of the guide device (5) designed as a stage diffuser.

14. The apparatus according to claim 12, characterized in that the branches (40, 41) are connected to the second or a subsequent stage of a channel of the guide device (5) designed as a stage diffuser immediately after one stage.

15. The apparatus according to claim 5, characterized gekenn¬ characterized in that the branches (59) to the nozzle chamber (29) are connected.

16. The device according to one of claims 4 - 15, characterized in that the branches control devices (15 - 18, 36) for the have flow or cross-sectional control of the feed or discharge of stock suspension and / or water.

17. The apparatus as claimed in claim 16, characterized in that measuring devices (21-25) distributed over the width of the headbox are provided for measuring the hydrostatic pressure of the stock suspension.

18. The apparatus according to claim 17, characterized gekenn¬ characterized in that a control device (26) is provided, which is controlled by the measuring devices (21 - 25) and regulates the flow and optionally the flow direction.

19. The device according to claim 18, characterized in that the control device (26) is set up to regulate the pressure across the width of the headbox to a predetermined pressure profile.

20. The apparatus according to claim 19, characterized in that measuring devices for properties of the paper web, in particular the surface weight or the fiber orientation, are provided over the width of the paper web produced, which devices are connected to the control device (26) and this has a specific pressure profile specify the width of the headbox.

21. Device according to one of claims 1-20, characterized in that means (27) for changing the cross-section of the channels (6) are provided.

22. Device according to one of claims 1-20, characterized in that means (50) for supplying water to the entrances (38) of the channels (6) are provided.

23. Device according to one of claims 1 - 22, characterized in that in front of the inlet openings (38) of the guide device (5) or after its outlet openings (43) adjustable elements (46, 47) for flow control by the guide device ( 5) are provided.

24. .Device according to one of claims 1 - 23, characterized in that the cross section of the channels (6) of the guide device (5) is different over the web width.

25. Device according to one of claims 1-23, characterized in that the channels (6) of the guide device (5) in the edge zones (48) of the headbox have a smaller pressure loss than in the central zone (49).

26. The device according to claim 25, characterized gekenn¬ characterized in that the guide device (5) in the edge zone has the same number of channels (6) per unit width, the cross sections of the channels (6) in the edge zone (48) are larger than in the middle zone (49).

27. The device according to claim 25, characterized in that additional bores (50) are provided in the guide device (5) in the edge zone (48).

28. Device according to one of claims 1-27, characterized in that the geometry of the distribution boxes (1) and / or the nozzle chamber (29) over the width of the headbox locally individually by means of an adjusting device (45) can be changed.

29. A method for operating the device according to any one of claims 1 - 28, characterized in that when changing the mass distribution of the stock suspension ^'over the web width of the Papier¬ machine by local variation of the width of the outlet gap and / or simultaneously by local variation of the fabric density, the Flow of the stock suspension in the headbox is adjusted so that seen across the web width of the paper machine, the horizontal component of the flow direction of the stock suspension at the outlet gap is parallel everywhere in the machine direction and the flow velocity in the outlet gap, seen across the machine width, is the same.

30. The method according to claim 29, characterized in that the setting of Flow optionally by changing the pressure profile in the distribution box, by changing the geometry of the distribution box, the guide device, or the nozzle space or by supplying or removing material suspension or supplying water in the distribution box, in the guide device or in the nozzle chamber, individually or in combination with one another.

31. The method according to claim 30, characterized gekenn¬ characterized in that the change in the pressure profile in the distribution box is carried out with a control device (26) by pressure measuring devices

(21 - 25) is controlled.

32. The method according to claim 31, characterized in that the control device (26) from sensors for properties of the paper web produced are supplied with control signals (28) which specify a specific pressure profile for the control device (26).