DE102009027079A1 - Headbox for a machine for producing a fibrous web - Google Patents

Abstract

The invention relates to a headbox (1) for a machine for producing a fibrous web (2), in particular a paper, board or tissue web, from at least one pulp suspension (3), having an upper nozzle wall (4) and a lower nozzle wall ( 5) and having two side walls (6), tapering to a spout (9) and one of the pulp suspension (3) during operation of the headbox (1) with a flow direction (S) through flowed interior (7) having headbox nozzle (8) , wherein on the upper nozzle wall (4) of the headbox nozzle (8) on the outlet side by means of several elements (10) displaceable and over the machine width (B) extending aperture (11) is arranged, which a diaphragm board (A) and a diaphragm immersion depth (T ) and during operation of the headbox (1) at least two of a pulp suspension (3) touched surfaces, an upstream ramp surface (12) and a nachgeo rdnete main surface (13), has. The headbox (1) according to the invention is characterized in that between the ramp surface (12) of the diaphragm (11) and the main surface (13) of the diaphragm (11) at least one during the operation of the headbox (1) of a pulp suspension (3) touched Refraction surface (17) on the diaphragm (11) is provided.

Description

The The invention relates to a headbox for a machine for producing a fibrous web, in particular a paper, Carton or tissue web, from at least one pulp suspension, with an upper nozzle wall and a lower nozzle wall as well as having two side walls, become an outlet rejuvenating and one of the pulp suspension during the operation of the headbox with a flow direction flowed through interior having headbox nozzle, wherein on the upper nozzle wall of the headbox nozzle outlet side a movable by means of several elements and over the machine width extending aperture is arranged, the one Iris board and has a iris immersion depth and the during the operation of the headbox at least two of a pulp suspension touched surfaces, an upstream Ramp surface and a subordinate main surface, having.

Such a headbox for a machine for producing a fibrous web, in particular a paper, board or tissue web, from at least one pulp suspension is for example from the German patent application DE 10 2004 047 879 A1 known.

A on an upper nozzle wall of a headbox nozzle a headbox arranged outlet side, preferably by means of several elements movable and over the machine width extending aperture is in a known manner for calibration of the Operating nozzle gap and for profiling, in particular for cross-profiling of the headbox leaving and at least a pulp suspension comprising pulp suspension jet used.

The The aim of this profiling today is usually the optimization fiber orientation, whereas earlier it was optimization of the cross section of the basis weight was. To now to obtain a good influenceability of the optimization, is with the Aperture a beam contraction for the at least one pulp suspension predetermined pulp suspension jet, with lower Adjustments to the aperture at higher beam contraction cause a stronger impact. The beam contraction generally causes alignment of the fibers in the at least a pulp suspension in its flow direction, that is in the machine direction. This orientation is especially at the varieties disadvantageous, where a low MD / CD strength ratio (MD: machine direction; CD: cross machine direction) must be achieved. To achieve this low strength ratio, In some cases, this is sometimes done on a headbox nozzle arranged panel completely omitted or a Regulierklappe, So a replaceable nozzle front part, provided. at However, a headbox without aperture can not profiling the Nozzle gaps are made more. In addition, you can Also, any production-related inaccuracies are no longer compensated become. The use of a regulating flap, however, allows Although a profiling of the nozzle gap, but in comparison with the aperture a very expensive solution.

The headbox of the already mentioned German Offenlegungsschrift DE 10 2004 047 879 A1 now has at the diaphragm on a contacted by a pulp suspension main surface which is parallel to the inner surface of the upper nozzle wall of the headbox.

In conducted trials and operational applications, such a headbox geometry in the end region of the headbox nozzle used, it has been shown that it is at the between the casserole the aperture and the main surface of the aperture trained as a kink Edge to disadvantageous flow separation in the at least one pulp suspension having pulp suspension flow comes. And these flow separations, in particular with only slightly converging headbox nozzles and strong employed panels, possibly even with small aperture boards are more pronounced and if necessary can also lead to a total stall, result in a known manner in more or less serious Problems in the production of the fibrous web. The problems can For example, poor cross-sections in the fibrous web produced be.

It So is the object of the invention, a headbox of the beginning mentioned type to improve so that a concern of at least a pulp suspension having pulp suspension flow at the aperture in all possible operating conditions and iris angles given continuously and reliably is.

These Task is in a headbox of the type mentioned in the present invention solved that between the casserole of the aperture and the main surface of the diaphragm at least one during the operation of the headbox touched by a pulp suspension Refraction surface is provided on the diaphragm. The while the operation of the headbox touched by a pulp suspension Refraction surface of the aperture can be directly or indirectly between the two surfaces of the panel be arranged the headbox.

The inventive object is in this way completely solved.

The inventive headbox improvement of the type mentioned ensures a perpetual and process-safe concern of at least one pulp suspension having pulp suspension flow at the orifice in all possible operating conditions. this will especially as a result of avoiding the previous trained as a kink Edge between the ramp surface of the panel and the main surface reached the aperture. The at least one inventive Refraction surface of the diaphragm between the ramp surface The aperture and the main surface of the aperture avoids effectively in the area of the headbox aperture a possible emergence of flow separation in the at least one Pulp suspension having pulp suspension flow. By this invention, that is new flow guides become strong accelerations the at least one pulp suspension having pulp suspension flow in the cross machine direction and high speeds avoided.

The recent, focusing on the emergence of flow separation possibly positive effects of the headbox, such as the degree of headbox convergence, the employment of the iris or the iris board, play the headbox improvement according to the invention of the type mentioned no longer essential.

In A first embodiment of the invention comprises during the operation of the headbox touched by a pulp suspension Refraction surface of the diaphragm - in the flow direction the at least one pulp suspension seen - a convex curved surface shape with a radius of curvature in the range of 0.1 to 5 mm, preferably 0.5 to 3 mm, in particular of 1 mm, on. The refraction surface of the diaphragm is - in the flow direction the at least one pulp suspension seen - the Bake surface of the diaphragm upstream and the main surface downstream of the diaphragm. The refraction surface of the aperture is therefore directly between the two mentioned areas of the Aperture of the headbox arranged.

And in a second embodiment of the invention, the during operation of the headbox from a pulp suspension touched refracting surface of the diaphragm - in Flow direction of the at least one pulp suspension seen - a convex curved surface shape with a radius of curvature in the range of ≥ 5 mm on. The refraction surface of the diaphragm is again directly or indirectly between the casserole of the aperture and the main surface of the aperture arranged.

Further In a third embodiment of the invention, FIG during operation of the headbox from a pulp suspension touched refracting surface of the diaphragm - in Flow direction of the at least one pulp suspension seen - a planar surface shape with an areal length in the range of 0.2 to 2 mm, preferably 0.5 to 1.5 mm, in particular of 1 mm, and preferably angle halving surface arrangement. The refraction surface of the diaphragm is again direct or indirectly between the casserole of the aperture and the main surface of the aperture arranged.

The during operation of the headbox from a pulp suspension touched refraction surface of the aperture is at the both last embodiments of the invention immediately between the ramp surface of the diaphragm and the main surface the aperture is placed when the casserole of the aperture the refractive surface of the diaphragm immediately upstream and the major surface of the aperture of the refracting surface the aperture is immediately downstream.

Of the during operation of the headbox from a pulp suspension touched refraction surface of the aperture can at the two last embodiments of the invention both inlet side and outlet side each have a further refractive side surface be upstream or downstream. In this case, the refraction surface the aperture then indirectly between the casserole of the aperture and the main surface of the diaphragm arranged. The refraction surface Of course, the aperture can only be one-sided adjoin a refractive side surface.

Farther may be the main surface contacted by a pulp suspension the aperture parallel to the inner surface of the upper nozzle wall be aligned with the headbox. This will at a low beam contraction for the at least a pulp suspension comprising pulp suspension jet both high microturbulence in the at least one pulp suspension as well as a low MD / CD strength ratio in the range of 1.1 to 2.5, in particular in the range of 1.8 to 2.0, achieved. In addition, the protective function of the aperture for the upper remains Exist nozzle wall.

Alternatively, the main surface of the diaphragm contacted by a pulp suspension may also be oriented at a divergent angle of up to 15 °, preferably of up to 10 °, in particular of up to 5 °, to the inner surface of the headbox upper nozzle wall. This is particularly advantageous if the run-up surface of the orifice and the inner surface of the upper nozzle wall of the headbox nozzle an angle in the range of ≤ 150 °, preferably of ≦ 135 °, in particular of ≦ 120 °. By this strongly employed run-up surface of the aperture, the deflection of the at least one pulp suspension having pulp suspension flow is very strong, thereby increasing the risk of stall significantly.

The Aperture also preferably has a dazzling board in Range from> 0 to 10 mm, preferably from 1 to 6 mm, in particular from 2 to 5 mm, on. This positive iris board means that the iris - in Flow direction of the at least one pulp suspension seen - from the top nozzle wall of the headbox nozzle protrudes, even if the shutter board for the purpose of profiling the at least one pulp suspension comprising pulp suspension jet must be reduced.

In order to a reapplication of the at least one fibrous suspension comprising Pulp suspension jet at the diaphragm continuously is given, it preferably has an aperture thickness in the range of 10 to 40 mm, preferably in the range of 12 to 25 mm. The Recovering the at least one pulp suspension comprising Fiber suspension jet at the aperture supported In addition, the achievement of a low beam contraction for the pulp suspension jet comprising at least one pulp suspension.

Farther The aperture can be below and in its height direction preferably be provided with a plurality of slots. In order to is an exact profiling of at least one pulp suspension comprehensive pulp suspension jet on a simple and inexpensive Way allows.

To the Purposes of stable and at least one-sided leadership the at least one pulp suspension comprising pulp suspension jet has the lower nozzle wall - in the flow direction the at least one pulp suspension seen - preferred a supernatant in the range of 6 to 30 mm, preferably in the range of 12 to 25 mm, opposite the aperture.

Further is the major surface touched by a pulp suspension the diaphragm preferably at a vertical distance of at least 6 mm, preferably at least 12 mm, from the lower nozzle wall arranged the headbox. These minimum sizes allow the generation of an optimal beam contraction upon achievement of the aforementioned properties.

Around the generation and maintenance of a minimum turbulence in the at least a pulp suspension having pulp suspension flow while flowing through the headbox nozzle to ensure that there are several in it Slats arranged, the downstream lamellar tips preferably in the area of the aperture. Thus, the slats preferably has a respective lamella length in the range of 50 to 98%, preferably in the range of 65 to 95%, of the length the headbox on.

Of the Headbox according to the invention can of course also as a multi-layer casserole with at least one separating element be executed.

Thereby can multilayer fibrous webs with different Layer qualities are generated.

Of the Headbox according to the invention is in excellent Also for use in a machine for making a Fiber web, in particular a paper, board or tissue web. In the machine with at least one invention Headbox produced fibrous web has consistently excellent Properties, in particular of the aforementioned type.

Further Features and advantages of the invention will become apparent from the following Description of several preferred embodiments with reference to the drawing.

It demonstrate

1 a vertical and schematic longitudinal sectional view of an embodiment of a headbox for a machine for producing a fibrous web according to the prior art; and

2 to 5 vertical and schematic longitudinal sectional views of embodiments of a headbox according to the invention for a machine for producing a fibrous web.

All 1 to 5 each show a headbox nozzle 8th a headbox 1 for a machine for producing a fibrous web 2 (see. 1 and 5 ) in a vertical and schematic longitudinal sectional view part. At the fibrous web 2 in particular, it may be a paper, board or tissue web.

The respective headbox 1 for a machine for producing a fibrous web 2 from at least one pulp suspension 3 (Arrow) comprises an upper nozzle wall 4 and a lower nozzle wall 5 (see. 1 and 5 ) and two side walls not explicitly shown 6 (see. 1 and 5 ). These four components 4 . 5 . 6 form an interior room 7 the headbox nozzle 8th from the pulp suspension 3 (Arrow) is flowed through and in the flow direction S (arrow) of the pulp suspension 3 (Arrow) to an outlet 9 rejuvenated. At the upper nozzle wall 4 is the outlet side by means of several elements 10 slidable and over the machine width B (arrow) extending aperture 11 arranged. The single element 10 For example, is formed as a threaded spindle which engages the top of the panel and in turn is actuated by a handwheel, an electric motor or the like.

The respectively in the 1 to 5 illustrated aperture 11 It has a shutter board A and a shutter immersion depth T. It also indicates during operation of the headbox 1 at least two of a pulp suspension 3 (Arrow) contacted surfaces, an upstream ramp surface 12 and one immediately (cf. 1 ) or indirectly (cf. 2 to 5 ) subordinate main surface 13 , on.

The in the 1 illustrated aperture 11 The prior art now shows one of a pulp suspension 3 (Arrow) touched main surface 13 on, parallel to the inner surface 14 the upper nozzle wall 4 runs (symbol representation). Between the casserole 12 the aperture 11 and the main surface 13 the aperture 11 So is an edge formed as a kink 15 intended. At this edge 15 it comes to flow separation (area 16 ) in the at least one pulp suspension 3 (Arrow) having pulp suspension flow. And these flow separations (area 16 ), which are particularly pronounced in only slightly converging headboxes and heavily employed diaphragms, where appropriate, even with small diaphragm boards and may possibly also lead to a total stall, resulting in a known manner in more or less serious problems in the production of the fibrous web. The problems may be, for example, poor cross-sections in the fibrous web produced.

The 2 to 5 show vertical and schematic longitudinal sectional views of four embodiments of a head box according to the invention 1 for a machine for producing a fibrous web 2 ,

It is between the ramp surface 12 the aperture 11 and the main surface 13 the aperture 11 at least one during operation of the headbox 1 from a pulp suspension 3 touched refraction surface 17 intended. This refraction surface 17 the respective aperture 11 can be directly or indirectly between the two mentioned areas 12 . 13 the aperture 11 of the headbox 1 be arranged.

Thus, in the embodiment of the 2 during the operation of the headbox 1 from a pulp suspension 3 touched refraction surface 17 the aperture 11 - In the flow direction S (arrow) of the at least one pulp suspension 3 (Arrow) - a convex curved surface shape 18 with a radius of curvature 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 the aperture 11 is directly between the two surfaces of the aperture 11 of the headbox 1 , the rampart 12 and the main surface 13 arranged.

In the embodiment of the 3 indicates the during the operation of the headbox 1 from a pulp suspension 3 touched refraction surface 17 the aperture 11 - In the flow direction S (arrow) of the at least one pulp suspension 3 (Arrow) - a convex curved surface shape 19 with a radius of curvature 19.R in the range of ≥ 5 mm.

And in the embodiment of the 4 indicates the during the operation of the headbox 1 from a pulp suspension 3 touched refraction surface 17 the aperture 11 - In the flow direction S (arrow) of the at least one pulp suspension 3 (Arrow) - a planar surface shape 20 with an areal length 20.L in the range of 0.2 to 2 mm, preferably of 0.5 to 1.5 mm, in particular of 1 mm, and angle halving surface arrangement. The angle halving surface arrangement of the planar surface shape 20 is indicated by the two equal angles γ. The planar surface shape 20 can of course also be arranged on one side.

In the two embodiments of the 3 and 4 is during the operation of the headbox 1 from a pulp suspension 3 touched refraction surface 17 the aperture 11 both inlet side and outlet side each have a further refractive side surface 19.1 . 19.2 respectively. 20.1 . 20.2 upstream or downstream. These two refractive surfaces 17 the aperture 11 So are indirectly between the two surfaces of the aperture 11 of the headbox 1 , the rampart 12 and the main surface 13 arranged.

Moreover, that is from a pulp suspension 3 (Arrow) touched main surface 13 the respective aperture 11 of the 2 to 4 parallel (symbol representation) to the inner surface 14 the respective upper nozzle wall 4 the headbox nozzle 8th aligned.

Furthermore, in the embodiment of the 5 that of a pulp suspension 3 (Arrow) touched main surface 13 the aperture 11 at a divergent angle β of up to 15 °, preferably of up to 10 °, in particular of up to 5 °, to the In inner face 14 the upper nozzle wall 4 the headbox nozzle 8th aligned. The casserole 12 the aperture 11 and the inner surface 14 the upper nozzle wall 4 the headbox nozzle 8th include an angle α in the range of ≤ 150 °, preferably of ≤ 135 °, in particular of ≤ 120 °, a.

In addition, the illustrated lower nozzle wall 5 the headbox nozzle 8th - In the flow direction S (arrow) of the at least one pulp suspension 3 (Arrow) - a supernatant Ü in the range of 6 to 30 mm, preferably in the range of 12 to 25 mm, relative to the diaphragm 11 on. Of course, also the lower nozzle walls, not shown, of the respective headbox nozzle 8th of the 2 to 4 have such a supernatant.

The during the operation of the headbox 1 from a pulp suspension 3 touched refraction surface 17 this aperture 11 can turn a convex curved surface shape 18 . 19 (see. 2 and 3 ) or a planar surface shape 20 (see. 4 ), optionally also with refractive surfaces 19.1 . 19.2 respectively. 20.1 . 20.2 (see. 3 and 4 ) be provided.

Also, the respective aperture indicates 11 of the 2 to 5 a diaphragm board A in the range of> 0 to 10 mm, preferably from 1 to 6 mm, in particular from 2 to 5 mm. This positive iris board A means that the single iris 11 - In the flow direction S (arrow) of the at least one pulp suspension 3 (Arrow) - from the upper nozzle wall 4 the headbox nozzle protrudes.

And the respective aperture of the 2 to 5 also has an aperture thickness D in the range of 10 to 40 mm, preferably in the range of 12 to 25 mm. In addition, it may, as exemplified in the embodiment of 2 is indicated, in its height direction H (arrow) with a plurality of slots 21 be provided (dashed line). The slots 21 may have rectangular and / or wedge-shaped and / or parabolic and / or round shapes.

The respective of a pulp suspension 3 (Arrow) touched main surface 13 the aperture 11 of the 2 to 5 is at a vertical distance C of at least 6 mm, preferably at least 12 mm, from the lower nozzle wall 5 the headbox nozzle 8th arranged (cf. 5 ).

And in the respective headbox 8th can, as in the embodiment of the 5 only indicated by dashed lines, several slats 22 be arranged, the downstream lamellar tips 23 preferably in the region of the aperture 11 lie. The slats 22 in this case 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 the headbox nozzle 8th on. Alternatively or additionally, the headbox 1 also be designed as a multi-layer casserole with at least one separating element.

The headbox 1 can in a further embodiment, with a sectioned substance density control (dilution water technology, "ModuleJet"), as for example from the German patent DE 40 19 593 C2 is known to be provided.

The in the 2 to 5 in each case at least partially illustrated and described headbox 1 is particularly suitable for use in a machine for producing a fibrous web, in particular a paper or board web, from at least one pulp suspension.

In summary It should be noted that a headbox of the invention initially mentioned type is improved such that a concern of the at least one pulp suspension having pulp suspension flow at the diaphragm in all possible operating conditions and Aperture angles is given continuously and reliably.

1

headbox

2

Fibrous web

3

Fibrous suspension (Arrow)

4

Upper nozzle wall

5

Lower nozzle wall

6

Side wall

7

inner space

8th

headbox

8.L

length the headbox nozzle

9

outlet

10

element

11

cover

12

upstream ramp surface

13

subordinate main area

14

palm

15

edge

16

burbling (Area)

17

refracting surface

18

Convex curved surface shape

18.R

radius of curvature

19

Convex curved surface shape

19.1

Refractive secondary area

19.2

Refractive secondary area

19.R

radius of curvature

20

planar surface shape

20.1

Refractive secondary area

20.2

Refractive secondary area

20.L

Overall length

21

slots

22

lamella

22.L

lamellar length

23

lamella tip

A

dazzle Board

B

machine width (Arrow)

C

vertical distance

D

iris thickness

H

height direction (Arrow)

S

flow direction (Arrow)

T

Baffle immersion depth

Ü

Got over

α

angle

β

angle

γ

angle

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - DE 102004047879 A1 [0002, 0005]
• - DE 4019593 C2 [0050]

Claims (15)

Headbox ( 1 ) for a machine for producing a fibrous web ( 2 ), in particular a paper, cardboard or tissue web, from at least one pulp suspension ( 3 ), with an upper nozzle wall ( 4 ) and a lower nozzle wall ( 5 ) as well as two side walls ( 6 ), become an outlet ( 9 ) tapered and one of the pulp suspension ( 3 ) during operation of the headbox ( 1 ) with a flow direction (S) through-flowed interior ( 7 ) headbox ( 8th ), wherein at the upper nozzle wall ( 4 ) of the headbox nozzle ( 8th ) on the outlet side by means of several elements ( 10 ) displaceable and over the machine width (B) extending aperture ( 11 ), which has an orifice board (A) and an iris immersion depth (T) and which during the operation of the headbox ( 1 ) at least two of a pulp suspension ( 3 ) contacted surfaces, an upstream ramp surface ( 12 ) and a subordinate main surface ( 13 ), characterized in that between the ramp surface ( 12 ) the aperture ( 11 ) and the main surface ( 13 ) the aperture ( 11 ) at least one during operation of the headbox ( 1 ) from a pulp suspension ( 3 ) touched refraction surface ( 17 ) at the aperture ( 11 ) is provided. Headbox ( 1 ) according to claim 1, characterized in that during operation of the headbox ( 1 ) from a pulp suspension ( 3 ) touched refraction surface ( 17 ) the aperture ( 11 ) - in the flow direction (S) of the at least one pulp suspension ( 3 ) - a convex curved surface shape ( 18 ) having a radius of curvature ( 18.K ) in the range of 0.1 to 5 mm, preferably 0.5 to 3 mm, in particular 1 mm. Headbox ( 1 ) according to claim 1, characterized in that during operation of the headbox ( 1 ) from a pulp suspension ( 3 ) touched refraction surface ( 17 ) the aperture ( 11 ) - in the flow direction (S) of the at least one pulp suspension ( 3 ) - a convex curved surface shape ( 19 ) having a radius of curvature ( 19.k ) in the range of ≥ 5 mm. Headbox ( 1 ) according to claim 1, characterized in that during operation of the headbox ( 1 ) from a pulp suspension ( 3 ) touched refraction surface ( 17 ) the aperture ( 11 ) - in the flow direction (S) of the at least one pulp suspension ( 3 ) - a planar surface shape ( 20 ) with an areal length ( 20.L ) in the range of 0.2 to 2 mm, preferably of 0.5 to 1.5 mm, in particular of 1 mm, and preferably angle (γ) halving surface arrangement. Headbox ( 1 ) according to claim 3 or 4, characterized in that during operation of the headbox ( 1 ) from a pulp suspension ( 3 ) touched refraction surface ( 17 ) the aperture ( 11 ) both on the inlet side and on the outlet side each have a further refraction side surface ( 19.1 . 19.2 ; 20.2 . 20.2 ) is upstream or downstream. Headbox ( 1 ) according to one of the preceding claims, characterized in that during operation of the headbox ( 1 ) from a pulp suspension ( 3 ) touched main surface ( 13 ) the aperture ( 11 ) parallel to the inner surface ( 14 ) of the upper nozzle wall ( 4 ) of the headbox nozzle ( 8th ) is aligned. Headbox ( 1 ) according to one of claims 1 to 5, characterized in that during operation of the headbox ( 1 ) from a pulp suspension ( 3 ) touched main surface ( 13 ) the aperture ( 11 ) at a divergent angle (β) of up to 15 °, preferably of up to 10 °, in particular of up to 5 °, to the inner surface ( 14 ) of the upper nozzle wall ( 4 ) of the headbox nozzle ( 8th ) is aligned. Headbox ( 1 ) according to claim 7, characterized in that the ramp surface ( 12 ) the aperture ( 11 ) and the inner surface ( 14 ) of the upper nozzle wall ( 4 ) of the headbox nozzle ( 8th ) include an angle (α) in the range of ≤ 150 °, preferably ≤ 135 °, in particular ≤ 120 °. Headbox ( 1 ) according to one of the preceding claims, characterized in that the diaphragm ( 11 ) has a diaphragm board (A) in the range of> 0 to 10 mm, preferably from 1 to 6 mm, in particular from 2 to 5 mm. Headbox ( 1 ) according to one of the preceding claims, characterized in that the diaphragm ( 11 ) has an aperture thickness (D) in the range of 10 to 40 mm, preferably in the range of 12 to 25 mm. Headbox ( 1 ) according to one of the preceding claims, characterized in that the lower nozzle wall ( 5 ) of the headbox nozzle ( 8th ) - in the flow direction (S) of the at least one pulp suspension ( 3 ) - a projection (Ü) in the range of 6 to 30 mm, preferably in the range of 12 to 25 mm, with respect to the diaphragm ( 11 ) having. Headbox ( 1 ) according to one of the preceding claims, characterized in that during operation of the headbox ( 1 ) from a pulp suspension ( 3 ) touched main surface ( 13 ) the aperture ( 11 ) at a vertical distance (C) of at least 6 mm, preferably of at least at least 12 mm, from the lower nozzle wall ( 5 ) of the headbox nozzle ( 8th ) is arranged. Headbox ( 1 ) according to one of the preceding claims, characterized in that in the headbox nozzle ( 8th ) several fins ( 22 ) are arranged, the downstream lamellar tips ( 23 ) preferably in the region of the diaphragm ( 11 ) lie. Headbox ( 1 ) according to one of the preceding claims, characterized in that it is designed as a multi-layer headbox with at least one separating element. Machine for producing a fibrous web ( 2 ), in particular a paper, cardboard or tissue web, with at least one headbox ( 1 ) according to one of claims 1 to 14.