HEADBOX FOR A MACHINE TO PRODUCE A FIBER WEB

Abstract

Headbox for a machine to produce a fiber web, in particular a paper, cardboard or tissue web from at least one fibrous suspension, having a headbox nozzle comprising an upper nozzle wall and a lower nozzle wall, as well as two side walls tapering to form an outlet, and having an inner chamber through which the fibrous suspension flows in flow direction during operation of headbox, whereby on upper nozzle wall of headbox nozzle a baffle is arranged on the outlet side which is movable by way of several elements and which extends across machine width, and which has a baffle protrusion and a baffle immersion depth and which has at least two surfaces—an upstream ramp surface and a subsequent main surface contacted by a fibrous suspension during operation of headbox. The inventive headbox is characterized in that between ramp surface of baffle and main surface of baffle at least one refraction surface which is in contact during operation of headbox with a fibrous suspension is provided on baffle.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of PCT application No. PCT/EP2010/055521, entitled “HEADBOX FOR A MACHINE FOR PRODUCING A FIBER WEB”, filed Apr. 26, 2010, which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a headbox for a machine to produce a fiber web, in particular a paper, cardboard or tissue web from at least one fibrous suspension, having a headbox nozzle comprising an upper nozzle wall and a lower nozzle wall, as well as two side walls tapering to form an outlet, and having an inner chamber through which the fibrous suspension flows in flow direction during operation of the headbox, whereby on the upper nozzle wall of the headbox nozzle a baffle is arranged on the outlet side which is movable by way of several elements and which extends across the machine width, and which has a baffle protrusion and a baffle immersion depth and which has at least two surfaces—an upstream ramp surface and a subsequent main surface contacted by a fibrous suspension during operation of the headbox.

2. Description of the Related Art

A headbox of this type for a machine to produce a fibrous web, in particular a paper, cardboard or tissue web from at least one fibrous suspension is known for example from German disclosure documentation DE 10 2004 047 879 A1.

A baffle arranged on the outlet side on an upper nozzle wall of a headbox nozzle in a headbox, movable preferably by way of several elements and extending over the machine width is used in an already known manner of calibrating the operating nozzle aperture and for profiling, in particular cross profiling of a fibrous suspension stream comprising at least one fibrous suspension, exiting the headbox. Currently the objective of this profiling is generally the optimization of the fiber orientation, whereas in the past it was the optimization of the cross profile of the surface related mass. In order to achieve a high level of influence over the optimization, a stream contraction is preset by the baffle for the fibrous suspension stream containing at least one fibrous suspension, whereby minor adjustments to the baffle at greater stream contraction cause a stronger effect. The stream contraction generally causes alignment of the fibers in the at least one fibrous suspension in direction of its flow, in other words in machine direction. This alignment is particularly disadvantageous in qualities in which a low MD/CD stability ratio (MD: machine direction; CD: cross machine direction) must be achieved. In order to achieve this low stability ratio a baffle that is arranged on the headbox is currently totally forgone in some cases, or an adjustment flap—in other words a replaceable nozzle front part—is provided. However, on a headbox without a baffle, profiling can no longer be implemented. Moreover, any possible production related inaccuracies can no longer be compensated for. Use of an adjustment flap allowing for profiling of the nozzle aperture is however a very expensive solution compared to the baffle.

The headbox in the referred to German disclosure document DE 10 2004 047 879 A1 has a main surface on the baffle which is contacted by the fibrous suspension and which progresses parallel to the inside surface of the upper nozzle wall of the headbox nozzle.

In trials which were conducted and in applications which utilized this type of headbox geometry in the end zone of the headbox nozzle it was demonstrated that on the edge in the form of a bend between the ramp surface of the baffle and the main surface of the baffle disadvantageous burbling occurs in the fibrous suspension flow containing at least one fibrous suspension. And these burbles which in particular are strongly defined with only slightly converging headbox nozzles and heavily pitched baffles, and also possibly with small baffle protrusions and which can possibly also lead to a total stall, result in a more or less known manner in serious problems in the production of the fiber web. The problems may for example be poor cross profiles in the produced fiber web.

It is therefore the objective of the current invention, and what is needed in the art is, to improve a headbox of the type described in the beginning so that contact of the fibrous suspension flow containing the at least one fibrous suspension on the baffle is maintained continuously and process-reliably during all possible operating conditions and baffle angles.

SUMMARY OF THE INVENTION

This objective is met with, and the present invention provides, a headbox of the type referred to at the beginning in that between the ramp surface of the baffle and the main surface of the baffle at least one refraction surface which is contacted during operation of the headbox by one fibrous suspension is provided on the baffle. The refraction surface of the baffle which is in contact during operation with a fibrous suspension can be arranged directly or indirectly between the two referred to surfaces of the baffle of the headbox.

The inventive objective is completely met in this manner.

The inventive improvement to the headbox of the type described at the beginning ensures continuous and process-reliable contact of the fibrous suspension flow containing the at least one fibrous suspension with the baffle during all possible operational conditions. This is achieved in particular as a result of avoiding the edge which was hitherto in the form of a bend between the ramp surface of the baffle and the main surface of the baffle. The at least one inventive refraction surface of the baffle between the ramp surface of the baffle and the main surface of the baffle effectively avoids a possible occurrence of burbles in the fibrous suspension flow containing at least one fibrous suspension in the area of the baffle of the headbox. By way of these inventive, in other words, new flow controls, strong acceleration in cross machine direction of the fibrous suspension flow containing the at least one fibrous suspension and high speeds are avoided.

The previous characteristics of the headbox which would possibly have a positive effect on the development of burbles, for example the degree of convergence of the headbox nozzle, pitch of the baffle or baffle protrusion, no longer represent a substantial role in the inventive improvement of the headbox of the type described in the beginning.

In a first embodiment of the invention the refraction surface of the baffle which is in contact with a fibrous suspension during operation of the headbox—viewed in flow direction of the at least one fibrous suspension—has a convex curved surface shape with a curvature radius in the range of 0.1 to 5 mm, preferably 0.5 to 3 mm, especially 1 mm. Viewed in flow direction of the at least one fibrous suspension, the ramp surface of the baffle is arranged upstream from the refraction surface of the baffle and the main surface of the baffle is arranged subsequent to it. The refraction surface of the baffle is therefore located directly between the two mentioned surfaces of the baffle of the headbox.

In a second embodiment of the invention the refraction surface of the baffle which is in contact with a fibrous suspension during operation of the headbox—viewed in flow direction of the at least one fibrous suspension—has a convex curved surface shape with a curvature radius in the range of ≧5 mm. The refraction surface of the baffle is again located directly or indirectly between the ramp surface of the baffle and the main surface of the baffle.

Moreover in a third embodiment of the invention the refraction surface of the baffle which is in contact with a fibrous suspension during operation of the headbox—viewed in flow direction of the at least one fibrous suspension—has a planar surface shape with a surface length in the range of 0.2 to 2 mm, preferably 0.5 to 1.5 mm, in particular 1 mm, and preferably an angle bisecting surface arrangement. The refraction surface of the baffle is hereby again arranged directly or indirectly between the ramp surface of the baffle and the main surface of the baffle.

In the last two embodiments of the invention the refraction surface of the baffle, which during operation of the headbox is in contact with a fibrous suspension, is located directly between the ramp surface of the baffle and the main surface of the baffle if the ramp surface of the baffle is located directly before the refraction surface of the baffle, and the main surface of the baffle is located directly after the refraction surface of the baffle.

In the two last-mentioned embodiments of the invention an infeed-side as well as an outlet side additional refraction side surface may be located before or respectively subsequent to the refraction surface of the baffle which is in contact with a fibrous suspension during operation of the headbox. The refraction surface of the baffle in this case is then arranged indirectly between the ramp surface of the baffle and the main surface of the baffle. The refraction surface of the baffle may however obviously also abut only on one side to an additional refraction side surface.

Moreover, the main surface of the baffle which is in contact with a fibrous suspension may be aligned parallel to the inside surface of the upper nozzle wall of the headbox nozzle. Hence, at a low stream contraction a high micro-turbulence as well as also a low MD/CD-stability ratio in the range of 1.1 to 2.5, especially in the range of 1.8 to 2.0 is achieved in the at least one fibrous suspension for the fibrous suspension stream comprising at least one fibrous suspension. Moreover, the protective function of the baffle for the upper nozzle wall is maintained.

Alternatively the main surface of the baffle may also be aligned below a divergent angle of up to 15°, preferably of up to 10°, in particular up to 5° to the inside surface of the upper nozzle wall of the headbox nozzle. This is especially advantageous if the ramp surface of the baffle and the inside surface of the upper nozzle wall of the headbox nozzle encompass an angle in the range of ≦150°, preferably ≦135°, in particular ≦120°. Due to this heavily pitched ramp surface of the baffle, the deflection of the fibrous suspension flow comprising at least one fibrous suspension is strongly defined, thereby clearly raising the risk of a stall in the flow.

The baffle moreover has a baffle protrusion preferably in the range of >0 to 10 mm, preferably 1 to 6 mm, in particular 2 to 5 mm. The positive baffle protrusion means that the baffle—viewed in flow direction of the at least one fibrous suspension—protrudes beyond the upper nozzle wall of the headbox nozzle, even if the baffle protrusion must be reduced for the purpose of profiling the fibrous suspension stream comprising at least one fibrous suspension.

In order to ensure continuous re-establishment of contact of the fibrous suspension stream comprising at least one fibrous suspension on the baffle, said baffle preferably has a baffle thickness in the range of 10 to 40 mm, preferably in the range of 12 to 25 mm. Re-establishment of contact of the fibrous suspension stream comprising at least one fibrous suspension on the baffle moreover positively supports that a low stream contraction is achieved in the fibrous suspension stream comprising at least one fibrous suspension.

The baffle can moreover be equipped on its underside and in its height direction preferably with a plurality of perforations. This allows for a precise profiling of the fibrous suspension stream comprising at least one fibrous suspension in a simple and cost-effective manner.

For the purpose of a stable and at least one-sided control of the at least one fibrous suspension stream comprising at least one fibrous suspension, the lower nozzle wall—viewed in flow direction of the at least one fibrous suspension—has a protrusion in the range of preferably 6 to 30 mm, preferably in the range of 12 to 25 mm compared to the baffle.

Moreover the main surface of the baffle which is in contact with a fibrous suspension is preferably arranged at a vertical distance of at least 6 mm, preferably at least 12 mm from the lower nozzle wall of the headbox nozzle. These minimum dimensions allow for the formation of optimum stream contraction while achieving the aforementioned characteristics.

In order to ensure formation and maintenance of a minimum turbulence in the fibrous suspension flow containing at least one fibrous suspension during the flow through the headbox nozzle, several lamellas are arranged in said headbox nozzle whose downstream lamella tips are located preferably in the area of the baffle. The lamellas therefore have a respective lamella length in the range of 50 to 98%, preferably in the range of 65 to 95% of the length of the headbox nozzle.

The inventive headbox can of course also be in the embodiment of a multi-layer headbox having at least one separator element. This allows for the production of multi-layer fiber webs having different layer qualities.

The inventive headbox is also ideally suited to be used in a machine for the production of a fiber web, in particular a paper, cardboard or tissue web. The fiber web produced in the machine comprising at least one inventive headbox has consistently excellent properties, in particular of the aforementioned type.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a vertical and schematic longitudinal sectional view of one version of a headbox for a machine to produce a fiber web according to the current state of the art; and

FIGS. 2-5 are vertical and schematic longitudinal sectional views of versions of an inventive headbox for a machine to produce a fiber web.

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

All FIGS. 1 through 5 respectively show a headbox nozzle 8 of a headbox 1 for a machine to produce a fiber web 2 (compare FIGS. 1 and 5) in a vertical and schematic longitudinal sectional view. The fiber web can in particular be a paper, cardboard or tissue web.

Respective headbox 1 for a machine to produce a fiber web 2 from at least one fibrous suspension 3 (arrow) comprises an upper nozzle wall 4 and a lower nozzle wall 5 (compare FIGS. 1 and 5), as well as two not explicitly illustrated side walls 6 (compare FIGS. 1 and 5). These four components 4, 5, 6 form an inner chamber 7 of headbox nozzle 8 through which fibrous suspension 3 (arrow) flows and which tapers in flow direction S (arrow) of fibrous suspension 3 (arrow) to form an outlet 9. On upper nozzle wall 4 a baffle 11 is arranged on the outlet side which is moveable by way of several elements 10 and which extends across machine width B (arrow). Individual element 10 is for example in the embodiment of a threaded spindle which engages on the top of the baffle and which is operable by way of a hand wheel, an electric motor or similar device.

Baffle 11, illustrated respectively in FIGS. 1 through 5, has a baffle protrusion A and a baffle immersion depth T. Moreover it has at least two surfaces which are in contact with a fibrous suspension 3 during operation of headbox 1—an upstream ramp surface 12 and a main surface 13 arranged directly (compare FIG. 1) or indirectly (compare FIGS. 2 through 5) subsequently thereto.

Baffle 11 illustrated in FIG. 1 according to the current state of the art has a main surface 13 which is in contact with a fibrous suspension 3 (arrow) and which progresses parallel to inside surface 14 of upper nozzle wall 4 (symbolic illustration). Between ramp surface 12 of baffle 11 and main surface 13 of baffle 11 an edge 15 is provided in the form of a bend. At this edge 15 burbling (zone 16) occurs in the fibrous suspension flow containing at least one fibrous suspension 3 (arrow). And these burbles (zone 16), which in particular are strongly defined with only slightly converging headbox nozzles and heavily pitched baffles and also possibly with small baffle protrusions and which can possibly also lead to a total stall in the flow, result in a more or less known manner in serious problems in the production of the fiber web. The problems may for example be poor cross profiles in the produced fiber web.

FIGS. 2 through 5 illustrate vertical and schematic longitudinal sectional views of four design forms of an inventive headbox 1 for a machine to produce a fiber web 2.

Between ramp surface 12 of baffle 11 and main surface 13 of baffle 11 at least one refraction surface 17 which is contacted during operation of headbox 1 by one fibrous suspension 3 is provided. This refraction surface 17 of respective baffle 11 can be arranged directly or indirectly between the two referred to surfaces 12, 13 of baffle 11 of headbox 1.

In the design variation illustrated in FIG. 2 the refraction surface 17 of baffle 11 which is in contact with a fibrous suspension 3 during operation of headbox 1—viewed in flow direction S (arrow) of the at least one fibrous suspension 3 (arrow)—has a convex curved surface shape 18 with a curvature radius 18.R in the range of 0.1 to 5 mm, preferably 0.5 to 3 mm, in particular 1 mm. This refraction surface 17 of baffle 11 is located directly between the two surfaces of baffle 11 of headbox 1, ramp surface 12 and main surface 13.

In the design variation illustrated in FIG. 3 the refraction surface 17 of baffle 11 which is in contact with a fibrous suspension 3 during operation of headbox 1—viewed in flow direction S (arrow) of the at least one fibrous suspension 3 (arrow)—has a convex curved surface shape 19 with a curvature radius 19.R in the range of ≧5 mm.

And in the design variation illustrated in FIG. 4 the refraction surface 17 of baffle 11 which is in contact with a fibrous suspension 3 during operation of headbox 1—viewed in flow direction S (arrow) of the at least one fibrous suspension 3 (arrow)—has a planar surface shape 20 with a surface length 20.L in the range of 0.2 to 2 mm, preferably 0.5 to 1.5 mm, in particular 1 mm, and an angle bisecting surface arrangement. The angle bisecting surface arrangement of planar surface form 20 is indicated by way of the two angles γ of the same size. Planar surface form 20 can obviously also be arranged one-sided.

In the two design variations illustrated in FIGS. 3 and 4 an infeed-side as well as an outlet-side additional refraction side surface 19.1, 19.2 or respectively 20.1, 20.2 is located upstream or respectively subsequent to the refraction surface 17 of baffle 11 which is in contact with a fibrous suspension 3 during operation of headbox 1. These two refraction surfaces 17 of baffle 11 are arranged indirectly between the two surfaces of baffle 11 of headbox 1, the ramp surface 12 and the main surface 13.

Moreover, main surface 13 of respective baffle 11 in FIGS. 2 through 4 (symbolic illustration) which is in contact with a fibrous suspension 3 (arrow) is aligned parallel to inside surface 14 of respective upper nozzle wall 4 of headbox nozzle 8.

Moreover, in the design variation illustrated in FIG. 5 the main surface 13 of baffle 11 is aligned below a divergent angle β of up to 15°, preferably of up to 10°, in particular up to 5° to inside surface 14 of upper nozzle wall 4 of headbox nozzle 8. Ramp surface 12 of baffle 11 and inside surface 14 of upper nozzle wall 4 of headbox nozzle 8 encompass an angle α in the range of ≦150°, preferably ≦135°, in particular ≦120°.

Besides, the illustrated lower nozzle wall 5 of headbox nozzle 8—viewed in flow direction S (arrow) of the at least one fibrous suspension 3 (arrow)—has a protrusion Ü in the range of 6 to 30 mm, preferably in the range of 12 to 25 mm compared to baffle 11. Of course, the non-illustrated lower nozzle walls of respective headbox nozzle 8 in FIGS. 2 through 4 can also feature a protrusion of this type.

Refraction surface 17 of this baffle 11 which is in contact with a fibrous suspension 3 during operation of headbox 1 can again feature a convex curved surface form 18, 19 (compare FIGS. 2 and 3), or a planar surface form 20 (compare FIG. 4), or can possibly also be provided with refraction side surfaces 19.1, 19.2 or respectively 20.1, 20.2 (compare FIGS. 3 and 4).

Respective baffle 11 illustrated in FIGS. 2 through 5 also has a baffle protrusion A in the range of >0 to 10 mm, preferably 1 to 6 mm, in particular 2 to 5 mm. This positive baffle protrusion A means that individual baffle 11—viewed in flow direction S (arrow) of the at least one fibrous suspension 3 (arrow)—protrudes beyond upper nozzle wall 4 of the headbox nozzle.

The respective baffle illustrated in FIGS. 2 through 5 has a baffle thickness D in the range of 10 to 40 mm, preferably in the range of 12 to 25 mm. It can moreover be equipped—as indicated in the example in the design form illustrated in FIG. 2—in its height direction H (arrow) with a plurality of perforations 21 (indicated by broken lines). Perforations 21 can be rectangular and/or wedge shaped and/or parabolic and/or round in their shape.

Respective main surface 13 of baffle 11 illustrated in FIGS. 2 through 5 which is in contact with a fibrous suspension 3 (arrow) is arranged at a vertical distance C of at least 6 mm, preferably at least 12 mm from lower nozzle wall 5 of headbox nozzle 8 (compare FIG. 5).

And, as indicated merely by broken lines in FIG. 5, several lamellas 22 can be arranged in respective headbox nozzle 8 whose downstream lamella tips 23 are located preferably in the area of baffle 11. Lamellas 22 hereby preferably have a respective lamella length 22.L in the range of 50 to 98%, preferably in the range of 65 to 95% of the length 8.L of headbox nozzle 8. Alternatively, or in addition headbox 1 may also be in the embodiment of a multi-layer headbox with at least one separator element.

In an additional embodiment, headbox 1 can also be equipped with sectioned stock consistency control (dilution water-technology “ModuleJet”) as is known for example from German patent document DE 40 19 593 C2.

Headbox 1 illustrated and described at least in sections in FIGS. 2 through 5 is especially suitable for use in a machine to produce a fiber web, in particular a paper or cardboard web from at least one fibrous suspension.

In summary it must be stated that a headbox of the type referred to at the beginning is improved by the current invention so that contact of the fibrous suspension flow containing at least one fibrous suspension on the baffle is maintained continuously and process-reliably during all possible operating conditions and baffle angles.

While this invention has been described with respect to at least one embodiment, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

COMPONENT IDENTIFICATION

1 Headbox

2 Fiber web

3 Fibrous suspension (arrow)

4 Upper nozzle wall

5 Lower nozzle wall

6 Side wall

7 Interior chamber

8 Headbox nozzle

8.L Length of headbox nozzle

9 Outlet

10 Element

11 Baffle

12 Upstream ramp surface

13 Subsequent main surface

14 Inside surface

15 Edge

16 Flow burbles (zone)

17 Refraction surface

18 Convex curved surface form

18.R Curvature radius

19 Convex curved surface form

19.1 Additional refraction side surface

19.2 Additional refraction side surface

19.R Curvature radius

20 Planar surface form

20.1 Additional refraction side surface

20.2 Additional refraction side surface

20.L Surface length

21 Perforations

22 Lamella

22.L Lamella length

23 Lamella tip

A Baffle protrusion

B Machine width (arrow)

C Vertical distance

D Baffle thickness

H Height direction (arrow)

S Flow direction (arrow)

T Baffle immersion depth (arrow)

Ü Protrusion

α Angle

β Angle

γ Angle

Claims

1. A headbox for a machine to produce a fiber web from at least one fibrous suspension, said fiber web being one of a paper web, a cardboard web, and a tissue web, said headbox comprising:

a headbox nozzle including an upper nozzle wall, a lower nozzle wall, two side walls tapering to form an outlet, and an inner chamber through which the fibrous suspension flows in a flow direction during an operation of the headbox, said upper nozzle wall including an outlet side;

a baffle, on said upper nozzle wall of said headbox nozzle said baffle being arranged on said outlet side, said baffle being movable by way of a plurality of elements, said baffle extending across a machine width, said baffle having a baffle protrusion and a baffle immersion depth, said baffle having at least two surfaces which include an upstream ramp surface and a subsequent main surface contacted by the fibrous suspension during said operation of the headbox, said baffle including thereon at least one refraction surface which is between said ramp surface of said baffle and said main surface of said baffle and which is in contact during said operation of the headbox with one said fibrous suspension.

2. The headbox according to claim 1, wherein said refraction surface of said baffle which is in contact with the fibrous suspension during said operation of the headbox, viewed in said flow direction of the at least one fibrous suspension, has a convex curved surface shape with a curvature radius in a range of 0.1 to 5 mm.

3. The headbox according to claim 1, wherein said refraction surface of said baffle which is in contact with the fibrous suspension during said operation of the headbox, viewed in said flow direction of the at least one fibrous suspension, has a convex curved surface shape with a curvature radius in a range of 0.5 to 3 mm.

4. The headbox according to claim 1, wherein said refraction surface of said baffle which is in contact with the fibrous suspension during said operation of the headbox, viewed in said flow direction of the at least one fibrous suspension, has a convex curved surface shape with a curvature radius of 1 mm.

5. The headbox according to claim 1, wherein said refraction surface of said baffle which is in contact with the fibrous suspension during said operation of the headbox, viewed in said flow direction of the at least one fibrous suspension, has a convex curved surface shape with a curvature radius in the range of ≧5 mm.

6. The headbox according to claim 1, wherein said refraction surface of said baffle which is in contact with the fibrous suspension during said operation of the headbox, viewed in said flow direction of the at least one fibrous suspension, has a planar surface shape with a surface length in a range of 0.2 to 2 mm and an angle bisecting surface arrangement.

7. The headbox according to claim 6, wherein said surface length is in a range of 0.5 to 1.5 mm.

8. The headbox according to claim 6, wherein said surface length is 1 mm.

9. The headbox according to claim 6, wherein said baffle includes an infeed-side refraction side surface and an outlet-side refraction side surface, said infeed-side refraction side surface being located upstream from said refraction surface of said baffle, said outlet-side refraction side surface being located subsequent to said refraction surface of said baffle, said refraction surface being in contact with the fibrous suspension during said operation of the headbox.

10. The headbox according to claim 1, wherein said upper nozzle wall includes an inside surface, said main surface of said baffle which is in contact with the fibrous suspension during said operation of the headbox being aligned parallel to said inside surface of said upper nozzle wall of said headbox nozzle.

11. The headbox according to claim 1, wherein said upper nozzle wall includes an inside surface, said main surface of said baffle which is in contact with the fibrous suspension during said operation of the headbox being aligned below a divergent angle of up to 15° to said inside surface of said upper nozzle wall of said headbox nozzle.

12. The headbox according to claim 11, wherein said divergent angle is up to 10°.

13. The headbox according to claim 11, wherein said divergent angle is up to 5°.

14. The headbox according to claim 11, wherein said ramp surface of said baffle and said inside surface of said upper nozzle wall of said headbox nozzle encompass an angle in a range of ≦150°.

15. The headbox according to claim 11, wherein said ramp surface of said baffle and said inside surface of said upper nozzle wall of said headbox nozzle encompass an angle in a range of ≦135°.

16. The headbox according to claim 11, wherein said ramp surface of said baffle and said inside surface of said upper nozzle wall of said headbox nozzle encompass an angle in a range of ≦120°.

17. The headbox according to claim 1, wherein said baffle protrusion is in a range of >0 to 10 mm.

18. The headbox according to claim 1, wherein said baffle protrusion is in a range of 1 to 6 mm.

19. The headbox according to claim 1, wherein said baffle protrusion is in a range of 2 to 5 mm.

20. The headbox according to claim 1, wherein said baffle has a baffle thickness in a range of 10 to 40 mm.

21. The headbox according to claim 1, wherein said baffle has a baffle thickness in a range of 12 to 25 mm.

22. The headbox according to claim 1, wherein said lower nozzle wall of said headbox nozzle, viewed in said flow direction of said at least one fibrous suspension, has a protrusion in a range of 6 to 30 mm compared to said baffle.

23. The headbox according to claim 1, wherein said lower nozzle wall of said headbox nozzle, viewed in said flow direction of said at least one fibrous suspension, has a protrusion in a range of 12 to 25 mm compared to said baffle.

24. The headbox according to claim 1, wherein said main surface of said baffle which is in contact with the fibrous suspension during said operation of the headbox is arranged at a vertical distance of at least 6 mm from said lower nozzle wall of said headbox nozzle.

25. The headbox according to claim 1, wherein said main surface of said baffle which is in contact with the fibrous suspension during said operation of the headbox is arranged at a vertical distance of at least 12 mm from said lower nozzle wall of said headbox nozzle.

26. The headbox according to claim 1, further including a plurality of lamellas which are arranged in said headbox nozzle, the headbox including an area of said baffle, said plurality of lamellas including a plurality of downstream lamella tips which are located in said area of said baffle.

27. The headbox according to claim 1, wherein the headbox is a multi-layer headbox having at least one separator element.

28. A machine to produce a fiber web from at least one fibrous suspension, the fiber web being one of a paper web, a cardboard web, and a tissue web, said machine comprising:

at least one headbox including: a headbox nozzle including an upper nozzle wall, a lower nozzle wall, two side walls tapering to form an outlet, and an inner chamber through which the fibrous suspension flows in a flow direction during an operation of said headbox, said upper nozzle wall including an outlet side; a baffle, on said upper nozzle wall of said headbox nozzle said baffle being arranged on said outlet side, said baffle being movable by way of a plurality of elements, said baffle extending across a machine width, said baffle having a baffle protrusion and a baffle immersion depth, said baffle having at least two surfaces which include an upstream ramp surface and a subsequent main surface contacted by the fibrous suspension during said operation of said headbox, said baffle including thereon at least one refraction surface which is between said ramp surface of said baffle and said main surface of said baffle and which is in contact during said operation of said headbox with one said fibrous suspension.