US20030159790A1

US20030159790A1 - Process and headbox of a machine for producing a fibrous material web

Info

Publication number: US20030159790A1
Application number: US10/372,934
Authority: US
Inventors: Wolfgang Ruf; Hans Loser
Original assignee: Voith Paper Patent GmbH
Current assignee: Voith Patent GmbH
Priority date: 2002-02-28
Filing date: 2003-02-26
Publication date: 2003-08-28
Also published as: EP1342834A3; EP1342834A2; DE10208640A1

Abstract

Process for forming and a headbox for producing a fibrous material web from a pulp suspension to form one of a paper or cardboard web. The headbox includes a headbox nozzle and at least one lamella, and the process includes providing a structured surface with at least one structure one of in and on a surface of the at least one lamella, such that the structured surface is arranged to generate cross flows inside the pulp suspension, whereby the cross flows lead to shear flows in the suspension stream.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119 of German Patent Application No. 102 08 640.0, filed on Feb. 28, 2002, the disclosure of which is expressly incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a process for producing a fibrous material web, in particular a paper and/or cardboard web, from a pulp suspension that is supplied from a headbox having a headbox nozzle provided with at least one lamella. The invention further relates to a headbox of a machine for producing a fibrous material web, in particular a paper and/or cardboard web, with a headbox nozzle that is provided with at least one lamella.

2. Discussion of Background Information

Processes and headboxes of the type mentioned at the outset are known, e.g., from German Application No. DE 43 21 697, European Application No. EP 0 211 607, Japanese Application No. JP 5-132885 and German Application No. DE 4329810.

According to German Application No. DE 43 29 810, a lamella end can be machined, e.g., in a sawtooth manner, in a stepwise manner or in a stepwise manner with rounded inner areas. Also described is a step lamella having an end area that narrows from the one side in a stepwise manner. Grooves can be machined in the end area of the lamella. Moreover, a grooved lamella is known from this printed publication, in which the grooves run at an angle to the main flow direction. The associated lamellar forms are used here to mechanically decouple individual areas of the lamella tip from one another, thus avoiding vibrations of the lamella.

The use of lamellae that are smooth in the area of the nozzle opening has heretofore been standard, and the hydraulic effect of cross flows has heretofore been generated by a so-called “tooth screen” and a so-called “shaker.”

SUMMARY OF THE INVENTION

The present invention provides process and an improved headbox of the type mentioned at the outset, in which shear flows can also be generated in the suspension stream.

According to the invention, a process is provided for producing a fibrous material web, e.g., a paper and/or cardboard web, from a pulp suspension that is supplied from a headbox. The headbox nozzle is provided with at least one lamella, in which the at least one lamella has a structured surface (i.e., a surface with relief or depressed structures) at least in some areas, and the structuring of the surface is selected to generate cross flows inside the suspension stream, which lead to shear flows in the suspension stream.

Thus, the lamella surface is advantageously correspondingly structured at least in the last third of the headbox nozzle, and preferably over its entire length Alternatively, the lamella surface is advantageously structured in the area of the nozzle discharge opening and preferably in a screen area of the nozzle discharge opening.

The associated shear flows in the suspension stream result in particular in an improvement in formation, a reduction of the breaking length ratio, the possibility of increasing the consistency, an increase in the strengths in the Z-direction and an improvement in the flatness result.

In the case of materials with a strong tendency to flocculation, both the formation and the strength values can be positively impacted by a more homogenous sheet structure, i.e., a more even distribution of the fibers, even at higher consistencies. An improved flatness of the finished web, e g., the finished paper, is achieved by a more homogenous sheet structure where there are no places with only fibers or only filler.

According to a preferred practical embodiment of the process according to the invention, the lamella surface is correspondingly structured exclusively in the area of the nozzle discharge opening and preferably exclusively in a screen area of the nozzle discharge opening.

In a preferred manner, the structuring is applied at an angle of 0° to 90°, preferably 20° to 70°, to the machine running direction. However, it can also be applied curved in such a way that the flow is aimed at the structure elements tangentially in the machine running direction and subsequently is diverted at an angle of 0° to 90°. Thus, the best conditions are created for generating shear flows in the suspension stream.

The structured lamella preferably extends through the nozzle opening to the outside.

For the optimal generation of cross flows, a respective structure expediently has a length/width ratio >2.

The lamella can be structured continuously up to the lamella tip.

Cross flows can be generated in particular which feature no surface effects compared with the tooth screen.

The lamella can also be structured in particular on two sides facing one another, in particular the top and bottom. In this case the structures provided on the two sides facing one another are advantageously oppositely oriented in order to minimize the resulting total impulse if necessary.

A respective structure can be formed by a recess or can be raised.

It is also advantageous if at least one structure is provided which is embodied, e.g., as a curved flow guide element. Thus, the associated structures can be optimally embodied as flow guide elements.

With an expedient practical embodiment of the process according to the invention, the structures are provided inside the headbox nozzle. Further, the structures can be provided in particular in the last third of the headbox nozzle viewed in the flow direction.

In certain cases it is also advantageous if structures are provided which generate flows running towards one another, thus balancing one another.

Structures can also be advantageously provided which generate directed flows remaining unidirectional. This can preferably be used for multi-layer technology.

In principle, the wall limiting the flow chamber of the headbox nozzle can also be structured.

According to a preferred practical embodiment, structures that interlock or fit together are provided on facing sides of adjacent lamellae and/or facing sides of a lamella and the nozzle wall.

According to a preferred embodiment of the process according to the invention, the lamella length and/or the structure depth, in particular the structure depth in the area of the nozzle opening, is correspondingly selected to adjust certain shear flows. By changing the lamella length and different structure depth or height at the opening, the relevant effect can be impacted by corresponding devices in the operation.

The structure depth preferably has a value in the range of 5% to 95%, preferably in the range of 20% to 80%, of the respective flow channel enclosed by the lamella, and/or in the range of 1% to 99%, preferably in the range of 10% to 95%, relative to the lamella thickness. However, the structure height preferably has a value in the range of 1% to 99%, preferably in the range of 20% to 80%, of the respective flow channel enclosed by the lamella,

The structuring itself features a partition in the range of 0.5 mm to 20 mm, preferably in the range of 2 mm to 10 mm, whereby the respective partition is constant and/or different in the machine running direction and/or in the cross-machine direction.

If a multi-layer headbox is used, at least one, preferably a middle layer, can be charged with long-fibered material to increase the strength.

A reflocking is prevented and a more homogenous sheet structure ensured by the additionally applied shear forces.

Moreover, the present invention provides a headbox of a machine for producing a fibrous material web, in particular a paper and/or cardboard web, with a headbox nozzle that is provided with at least one lamella. The at least one lamella is provided with a surface that is structured at least in some areas, whereby the structuring is preferably selected such that cross flows are generated inside the suspension stream, which cross flows lead to shear flows in the suspension stream,

Preferred embodiments of the headbox according to the invention are disclosed in the dependent claims.

The present invention is directed to a process for producing a fibrous material web from a pulp suspension that is supplied from a headbox having a headbox nozzle with at least one lamella. The process includes supplying a pulp suspension stream toward the headbox nozzle, and generating cross flows inside the pulp suspension stream due to structures one of in and on a surface of the at least one lamella. In this manner, the cross flows lead to shear flows in the suspension stream.

The instant invention is directed to a process for forming a headbox for producing a fibrous material web from a pulp suspension to form one of a paper or cardboard web. The headbox includes a headbox nozzle and at least one lamella, and the process includes providing a structured surface with at least one structure one of in and on a surface of the at least one lamella, such that the structured surface is arranged to generate cross flows inside the pulp suspension, whereby the cross flows lead to shear flows in the suspension stream.

According to a feature of the invention, the lamella surface can be structured at least in the last one-third of the headbox nozzle. Further, the lamella surface is structured over its entire length.

Moreover, the lamella surface can be structured in a region of a nozzle discharge opening. Also, the lamella surface is structured in a lip area of the nozzle discharge opening. Further, the lamella surface can be structured exclusively in the region of the nozzle discharge opening, and the lamella surface may be structured exclusively in the lip area of the nozzle discharge opening

The at least one structure can be arranged at an angle of between 0° and 90° to a machine running direction, and, preferably, the at least one structure is arranged at an angle of between 20° and 70° to the machine running direction.

In accordance with another feature of the invention, the at least one structure may be curved so that the suspension steam is tangentially aimed at the structures in a machine running direction and is subsequently diverted at an angle of 0° to 90°.

According to another feature, the at least one lamella can extend through a nozzle opening to outside of the headbox nozzle.

In accordance with still another feature of the present invention, the at least one structure has a length/width ratio (L/B)>2.

According to a further feature, the at least one lamella can be structured continuously up to a lamella tip.

The at least one lamella may include at least two lamella arranged so that one side of each lamella face each other, and the process can further include providing the at least one structure on each of the facing sides of the at least two lamella. The at least one structure can be provided on the two facing sides of the at least two lamella are arranged to be oppositely oriented,

In accordance with the invention, the at least one structure may include a recess formed in the at least one lamella.

Still further, the at least one structure may include a structure raised above the surface of the lamella.

Further still, the at least one structure can include a curved flow guide element.

The at least one structure can be located inside the headbox nozzle, and the at least one structure can be provided in a last one-third of the headbox nozzle viewed in a flow direction.

In accordance with a still further feature of the instant invention, the at least one structure can include a plurality of structures arranged to generate flows running towards one another, thereby balancing one another.

Further, the at least one lamella can be arranged to form a multi-layer headbox, and the at least one structure may include a plurality of structures arranged to generate unidirectional flows.

Moreover, a headbox can be provided for performing the above-noted process, in which the headbox nozzle is defined by at least one wall, and the at least one wall includes at least one structure one of in and on a wall surface arranged to face the pulp suspension stream.

In accordance with still another feature of the invention, the at least one lamella may include at least two lamellae having sides arranged to face each other and each of the at least two lamellae includes at least one structure, and the at least one structures are at least one of arranged on facing sides of the at least two lamellae to interlock or fit together are provided on facing sides of adjacent lamellae and arranged on facing sides of at least one of the at least two lamellae and a nozzle wall to interlock or fit together.

The process can also include selecting at least one of a length of the at least one lamella and one of a depth or height of the at least one structure to adjust certain shear flows. The one of the depth or height of the at least one structure can be arranged in a region of the nozzle opening. In particular, the depth of the at least one structure may have a value in the range of 5% to 95% of a flow channel enclosed by the at least one lamella, and, preferably, the depth has a value in the range of 20% to 80% of the flow channel enclosed by the lamella. Further, the depth of the at least one structure may have a value in the range of 1% to 99% of a thickness of the lamella, and preferably, the depth has a value in the range of 10% to 95% of the lamella thickness. Still further, a height of the at least one structure can have a value in the range of 1% to 99% of the flow channel enclosed by the lamella, and, preferably, the height has a value in the range of 20% to 80% of the flow channel enclosed by the lamella.

According to another feature of the present invention, the at least one structure may include a plurality of structures and the at least one lamella can further include a partition in the range of 0.5 mm to 20 mm between the plurality of structures, in which the partition range is at least one of constant or different in at least one of the machine or cross machine directions. The partition range can be between 2 mm and 10 mm.

Moreover, the headbox can include a multi-layer headbox, and the process may further include charging a middle layer of the multi-layer headbox with long-fibered material to increase the strength.

Still further, a headbox of a machine can be provided for performing the above-noted process to produce a fibrous material web. The headbox includes the headbox nozzle, the at least one lamella is located within the headbox nozzle having the structured surface at least in some areas comprising at least one structure arranged at least one of in and on the surface of the at least one lamella, and the structured surface being arranged to generate cross flows inside a suspension stream, whereby the cross flows lead to shear flows in the suspension stream.

The present invention is directed to a headbox of a machine for producing a fibrous material web to form one of a paper or cardboard web. The headbox includes a headbox nozzle, at least one lamella located within the headbox nozzle, having a structured surface at least in some areas comprising at least one structure arranged at least one of in and on the surface of the at least one lamella, and the structured surface being arranged to generate cross flows inside a suspension stream, whereby the cross flows lead to shear flows in the suspension stream.

According to a feature of the instant invention, the at least one structure may include a curved structure arranged so that the suspension stream is tangentially aimed at the at least one structure in a machine direction and is subsequently diverted at an angle of 0° to 90°.

In accordance with another feature of the invention, the at least one lamella may include at least two lamellae having sides arranged to face each other, and each of the facing sides comprise the structured surface. The at least one structures on the facing sides of the at least two lamellae can be arranged to be oppositely oriented.

According to the invention, the at least one structure may include a recess formed in the at least one lamella, a structure raised above the surface of the at least one lamella, and/or a curved flow guide element.

The at least one structure can include a plurality of structures arranged to generate flows running towards one another thereby balancing one another.

Further, the headbox can include a multi-layer headbox, and the structured surface can be arranged to generate unidirectional flows.

The headbox nozzle can be delimited by at least one wall, and the at least one wall may include a structured surfaces arranged to face the pulp suspension stream.

Moreover, the at least one lamella can include at least two lamellae having sides arranged to face each other and each of the at least two lamellae may include a structured surface, and the structured surfaces are at least one of arranged to face each other with structures of the structured surfaces arranged to interlock or fit together or arranged on facing sides of one at least one of the lamella and a nozzle wall with structures of the structured surface and wall arranged to interlock or fit together.

In accordance with another feature of the instant invention, the structured surface may include at least two structures separated by a partition, and the partition may have a distance or thickness in a range of 0.5 mm to 20 mm, in which the partition range is at least one of constant or different in at least one of a machine and a cross machine direction. Preferably, the partition distance or thickness is in the range of 2 mm to 10 mm.

In accordance with still yet another feature of the present invention, the headbox may include a multi-layer headbox arranged to be charged with long-fibered material. Further, a middle layer in the multi-layer headbox can be charged with the long-fibered material.

Other exemplary embodiments and advantages of the present invention may be ascertained by reviewing the present disclosure and the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of exemplary embodiments of the present invention, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein: [0067]
FIG. 1 diagrammatically illustrates a plan view of a part of an exemplary structured lamella surface; [0068]
FIG. 2 diagrammatically illustrates a longitudinal sectional view of a part of an embodiment of a headbox nozzle with a lamella structured in the screen area; [0069]
FIG. 3 diagrammatically illustrates a longitudinal sectional view of a part of another embodiment of a headbox nozzle with a lamella structured continuously up to the lamella tip; [0070]
FIG. 4 diagrammatically illustrates a longitudinal sectional view of a part of another embodiment of a headbox nozzle with two lamellae structured in the screen area, whereby the lamellae are structured both on the top and on the bottom; [0071]
FIG. 5 diagrammatically illustrates a longitudinal sectional view of a part of another embodiment of a headbox nozzle with two lamellae structured in the screen area, whereby the lamellae are each structured only on the sides facing the other lamella; and [0072]
FIG. 6 diagrammatically illustrates a longitudinal sectional view of a part of another embodiment of a headbox nozzle with a lamella structured inside the headbox nozzle, whereby the wall limiting the flow chamber of the headbox nozzle is also structured.[0073]

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show structural details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the present invention may be embodied in practice. [0074]
FIG. 1 shows in diagrammatic plan view a part of a [0075] lamella 10 assigned to a headbox nozzle. Moreover, a screen 12 can be seen which is arranged in the area of the discharge opening of the headbox nozzle and through which the discharge opening of the headbox nozzle can be correspondingly varied.
In the present case the lamella surface is structured in the area of the [0076] screen 12.
As can be seen from FIG. 1, a respective structure, i.e., an [0077] individual structure element 14 of the overall provided structuring 16, formed in and/or on the lamella surface can have, e.g., a length/width ratio L/B>2. The length L of individual structure element 14 is thereby measured in flow direction S (arrow) of the fibrous material suspension and width B is measured in the crosswise direction.
[0078] Individual structure elements 14 are arranged parallel to one another and are preferably obliquely oriented (slanted) with respect to flow direction S (arrow). Structure elements 14 can be formed or embodied, e.g., as longitudinal grooves, in which width 13 is largest in the middle and tapers towards both ends (see, e.g., the depiction by solid lines). Moreover, structure elements 14, e.g., of the type shown by dotted lines in FIG. 1 can also be provided, in which the structure is raised above the lamella surface.
A corresponding structuring can be provided on the top and/or on the bottom of [0079] respective lamella 10.
Furthermore, structuring [0080] 16 is applied at an angle a of 0° to 90°, preferably 20° to 70°, to the machine running direction (flow direction S (arrow)). In another embodiment, structuring 16 can also be applied in a curved manner such that the flow is aimed tangentially at individual structure elements 14 in the machine running direction (flow direction S (arrow)) so as to be subsequently diverted at an angle of 0° to 90°.
[0081] Structuring 16 can further include a partition T between adjacent individual structures 14 having a thickness/distance in a range of 0.5 mm to 20 mm, preferably in the range of 2 mm to 10 mm. In this way, partition T can be constant and/or different in the machine running direction and/or in the cross-machine direction, whereby any embodiment of partition T is possible.
The respective surfaces of [0082] lamellae 10 shown in FIGS. 2 through 5 can also have, e g., such a structuring again.
FIG. 2 shows, in a diagrammatic longitudinal sectional view, a part of an embodiment of a [0083] headbox nozzle 18 having a flow chamber 20 limited by an upper wall 22 and a lower wall 24. A lip or screen 12 is provided at the end of upper wall 22 on an opening side, by which the discharge opening of headbox nozzle 18 can be varied. Lower wall 24 extends in flow direction S (arrow) beyond the end of upper wall 22 at the opening side or beyond lip 12 provided there.
[0084] Headbox nozzle 18 is provided with a lamella 10 structured in the area of lip 12 on both its top surface and on its bottom surface. Such individual structure elements 14, for example, can be respectively provided again thereby as shown in FIG. 1. Moreover, in this embodiment, the structuring is again provided in the area of lip 12, and only in this lip area. Lamella 10 extends out of flow chamber 20 in flow direction S (arrow) via the discharge opening to the outside. It also extends in particular thereby beyond the respective end of lower wall 24. In the present case, lamella 10 is not structured in the area of tip 26.
[0085] Individual structure elements 14 can again be respectively formed by a recess (see, e g., depiction by solid lines) or raised above the surface (see, e.g., depiction by dotted lines).
The recessed structuring features a structure depth t, which has a value in the range of 5% to 95%, preferably in the range of 20% to 80%, of the respective flow channel enclosed by [0086] lamella 10, or a value in the range of 1% to 99%, preferably in the range of 10% to 95%, with respect to lamella thickness D.
FIG. 3 shows a representation of a [0087] headbox nozzle 18 comparable with FIG. 2, however, in the present case, lamella 10 is also structured in the area of tip 26. Further, it is noted that lamella 10 is again structured on its top surface as well as on its bottom surface both in the regions of lip 12 and in the area of tip 26. Individual structure elements 14′ extending into the area of tip 26 connect directly with individual structure elements 14 provided in the area of lip 12.
In a further embodiment, the lamella surface can also be correspondingly structured at least in the last third of [0088] headbox nozzle 18, and preferably over its entire length.
Otherwise, the headbox can again have the same structure as that according to FIG. 2, at least essentially. Corresponding parts have been assigned the same reference numbers. [0089]
FIG. 4 shows an embodiment of a headbox comparable with FIG. 2, however, in the present case two [0090] lamellae 10 are arranged one above the other. The two lamellae 10 are again structured on both sides like the lamella depicted in FIG. 2. In the present case, structuring 16 is respectively provided in the area of lip 12.
Further, in the present case, two [0091] lamellae 10 are at least essentially formed or embodied like the lamella depicted and described in FIG. 2. In this manner, individual structure elements 14 can be embodied and oriented, e.g., as shown in FIG. 1 and described on the basis of this FIG. 1.
Otherwise this embodiment can also, e.g., at least essentially again have the same structure as that in FIG. 2, whereby corresponding parts have again been assigned the same reference numbers. [0092]
FIG. 5 shows a representation of a headbox comparable with FIG. 4. However, in the present case, the two [0093] lamellae 10 are structured respectively only on the sides facing the other lamella.
In this embodiment, [0094] individual structures 14 can be provided again in particular in the area of lip 12. Otherwise this embodiment can at least essentially again also have the same structure as that of FIG. 4. Corresponding parts have again been assigned the same reference numbers.
Further, [0095] individual structures 14 can again be formed respectively by a recess (see, e.g., the depiction by solid lines) or can be raised above the surface (see, e.g., the depiction by dotted lines). Moreover, as depicted on the right-hand portion of FIG. 5, individual structures 14 can also be formed or embodied so as to interlock or fit together.
In the exemplary embodiments described above, the structuring is selected in particular such that cross flows are generated inside the suspension stream, and these cross flows lead to shear flows in the suspension stream. A structure is preferably applied to a respective lamella in the lip area of the nozzle discharge opening, by which structure the cross flows are generated inside the stream. [0096]
With regard to structures raised above the surface of the lamella, see, e.g., FIG. 5, a structure height h has a value in the range of 1% to 99%, preferably in the range of 20% to 80%, of the respective flow channel enclosed by the [0097] lamella 10.
FIG. 6 shows in diagrammatic longitudinal sectional view a part of another embodiment of a [0098] headbox nozzle 18 in which flow chamber 20 is limited by upper wall 22 and lower wall 24. Lip 12 is again provided at the end of upper wall 22 on the opening side.
In this exemplary embodiment, [0099] headbox nozzle 18 is provided with a lamella 10 structured inside flow chamber 20, which lamella is structured on both the top and the bottom. In this particular embodiment, individual structure elements 14 are raised above the lamella surface. As can be seen from FIG. 6, individual structure elements 14 are also provided on upper wall 22 and lower wall 24, thereby limiting flow chamber 20 of headbox nozzle 18. Individual structure elements 14 provided on lamella 10 or on walls 22 and 24, can also be formed or embodied, e.g., to interlock or fit together.
To produce the desired cross flows, the structures or individual structure elements preferably have a length/width ratio of L/B>2. [0100]
The structures can also be continuous up to the lamella tip (see, e.g., FIG. 3). Further, compared with a so-called tooth screen, the cross flows generate no surface effects. [0101]
If both the top and bottom of the lamella is structured, the relevant structures can be oppositely oriented, in order to minimize the resulting total impulse if necessary. [0102]
The effect can be influenced by corresponding devices in the operation by a change in the lamella length or depth and different structure depths or heights, particularly in the area of the nozzle opening. [0103]
With pulps with a strong tendency to flocculation, both the formation and the strength values can be positively impacted, even with higher consistencies, by a more homogenous sheet structure, i.e., a more uniform distribution of the fibers. A better flatness of the finished paper is also achieved by a more homogenous sheet structure, in which there are no places where there are only fibers or only filler. [0104]
In the case of a multi-layer headbox, at least one layer, preferably a middle layer, can be charged with long-fibered material to increase the strength. A reflocking is prevented and a more homogenous sheet structure is ensured by the additionally applied shear forces. [0105]
According to the invention, an improved formation, a reduction of the breaking length ratio, the possibility of increasing the consistency, an increase in the strengths in the Z direction and an improvement in the flatness result with the shear flows generated in the suspension stream. [0106]
It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present invention. While the present invention has been described with reference to an exemplary embodiment, it is understood that the words which have been used herein are words of description and illustration, rather than words of limitation. Changes may be made, within the purview of the appended claims, as presently stated and as amended, without departing from the scope and spirit of the present invention in its aspects. Although the present invention has been described herein with reference to particular means, materials and embodiments, the present invention is not intended to be limited to the particulars disclosed herein; rather, the present invention extends to all functionally equivalent structures, methods and uses., such as are within the scope of the appended claims. [0107]

LIST OF REFERENCE NUMBERS



	10	Lamella
	12	Screen
	14	Structure element
	16	Structuring
	18	Headbox nozzle
	20	Flow chamber
	22	Upper wall
	24	Lower wall
	26	Lamella tip
	B	Width (structure element)
	D	Lamella thickness
	h	Structure height (structuring)
	L	Length (structure element)
	S	Flow direction (arrow)
	t	Structure depth (structuring)
	T	Partition (structuring)
	α	Angle

Claims

What is claimed:

1. A process for producing a fibrous material web from a pulp suspension that is supplied from a headbox having a headbox nozzle with at least one lamella, the process comprising:

supplying a pulp suspension stream toward the headbox nozzle; and

generating cross flows inside the pulp suspension stream due to structures one of in and on a surface of the at least one lamella, whereby the cross flows lead to shear flows in the suspension stream.

2. A process for forming a headbox for producing a fibrous material web from a pulp suspension to form one of a paper or cardboard web, the headbox including a headbox nozzle and at least one lamella, the process comprising:

providing a structured surface with at least one structure one of in and on a surface of the at least one lamella, wherein the structured surface is arranged to generate cross flows inside the pulp suspension, whereby the cross flows lead to shear flows in the suspension stream.

3. The process in accordance with claim 2, wherein the lamella surface is structured at least in the last one-third of the headbox nozzle.

4. The process in accordance with claim 3, wherein the lamella surface is structured over its entire length.

5. The process in accordance with claim 2, wherein the lamella surface is structured in a region of a nozzle discharge opening.

6. The process in accordance with claim 5, wherein the lamella surface is structured in a lip area of the nozzle discharge opening.

7. The process in accordance with claim 5, wherein the lamella surface is structured exclusively in the region of the nozzle discharge opening.

8. The process in accordance with, claim 7, wherein the lamella surface is structured exclusively in the lip area of the nozzle discharge opening.

9. The process ill accordance with claim 2, wherein the at least one structure is arranged at an angle of between 0° and 90° to a machine running direction.

10. The process in accordance with claim 9, wherein the at least one structure is arranged at an angle of between 20° and 70° to the machine running direction.

11. The process in accordance with claim 2, wherein the at least one structure is curved so that the suspension steam is tangentially aimed at the structures in a machine running direction and is subsequently diverted at an angle of 0° to 90°.

12. The process in accordance with claim 2, wherein the at least one lamella extends through a nozzle opening to outside of the headbox nozzle.

13. The process in accordance with claim 2, wherein the at least one structure has a length/width ratio (L/B)>2.

14. The process in accordance with claim 2, wherein the at least one lamella is structured continuously up to a lamella tip.

15. The process in accordance with claim 2, wherein the at least one lamella comprises at least two lamella arranged so that one side of each lamella face each other, and the process further comprises:

providing the at least one structure on each of the facing sides of the at least two lamella.

16. The process in accordance with claim 15, wherein the at least one structure provided on the two facing sides of the at least two lamella are arranged to be oppositely oriented.

17. The process in accordance with claim 2, wherein the at least one structure comprises a recess formed in the at least one lamella.

18. The process in accordance with claim 2, wherein the at least one structure comprises a structure raised above the surface of the lamella.

19. The process in accordance with claim 2, wherein the at least one structure comprises a curved flow guide element.

20. The process in accordance with claim 2, wherein the at least one structure is located inside the headbox nozzle.

21. The process in accordance with claim 20, wherein the at least one structure is provided in a last one-third of the headbox nozzle viewed in a flow direction.

22. The process in accordance with claim 2, wherein the at least one structure is comprises a plurality of structures arranged to generate flows running towards one another, thereby balancing one another.

23. The process in accordance with claim 2, wherein the at least one lamella is arranged to form a multi-layer headbox, and the at least one structure comprises a plurality of structures arranged to generate unidirectional flows.

24. A headbox for performing the process in accordance with claim 2, wherein said headbox nozzle is defined by at least one wall, and said at least one wall comprises at least one structure one of in and on a wall surface arranged to face the pulp suspension stream.

25. The process in accordance with claim 2, wherein the at least one lamella comprises at least two lamellae having sides arranged to face each other and each of the at least two lamellae includes at least one structure, and the at least one structures are at least one of arranged on facing sides of the at least two lamellae to interlock or fit together are provided on facing sides of adjacent lamellae and arranged on facing sides of at least one of the at least two lamellae and a nozzle wall to interlock or fit together.

26. The process in accordance with claim 2, further comprising selecting at least one of a length of the at least one lamella and one of a depth or height of the at least one structure to adjust certain shear flows.

27. The process in accordance with claim 26, wherein the one of the depth or height of the at least one structure is arranged in a region of the nozzle opening.

28. The process in accordance with claim 26, wherein the depth of the at least one structure has a value in the range of 5% to 95% of a flow channel enclosed by the at least one lamella.

29. The process in accordance with claim 28, wherein the depth has a value in the range of 20% to 80% of the flow channel enclosed by the lamella.

30. The process in accordance with claim 26, wherein the depth of the at least one structure has a value in the range of 1% to 99% of a thickness of the lamella.

31. The process in accordance with claim 30, wherein the depth has a value in the range of 10% to 95% of the lamella thickness.

32. The process in accordance with claim 26, wherein a height of the at least one structure has a value in the range of 1% to 99% of the flow channel enclosed by the lamella.

33. The process in accordance with claim 32, wherein the height has a value in the range of 20% to 80% of the flow channel enclosed by the lamella.

34. The process in accordance with claim 2, wherein the at least one structure comprises a plurality of structures and the at least one lamella further includes a partition in the range of 0.5 mm to 20 mm between the plurality of structures, in which the partition range is at least one of constant or different in at least one of the machine or cross machine directions.

35. The process in accordance with claim 34, wherein the partition range is between 2 mm and 10 mm.

36. The process in accordance with claim 2, wherein the headbox comprises a multi-layer headbox, and the process further comprises charging a middle layer of the multi-layer headbox with long-fibered material to increase the strength.

37. A headbox of a machine for performing the process in accordance with claim 2 to produce a fibrous material web, said headbox comprising:

the headbox nozzle;

the at least one lamella being located within said headbox nozzle having a structured surface at least in some areas comprising at least one structure arranged at least one of in and on said surface of said at least one lamella; and

said structured surface being arranged to generate cross flows inside a suspension stream, whereby the cross flows lead to shear flows in the suspension stream.

38. A headbox of a machine for producing a fibrous material web to form one of a paper or cardboard web, comprising:

a headbox nozzle;

at least one lamella located within said headbox nozzle, having a structured surface at least in some areas comprising at least one structure arranged at least one of in and on said surface of said at least one lamella; and

39. The headbox in accordance with claim 38, wherein said surface of said at least one lamella is structured at least in a last third of said headbox nozzle.

40. The headbox in accordance with claim 39, wherein said surface is structured over its entire length.

41. The headbox in accordance with claim 38, wherein said surface of said at least one lamella is structured in a region of a nozzle discharge opening.

42. The headbox in accordance with claim 41, wherein said surface is structured in a region of a lip of said nozzle discharge opening.

43. The headbox in accordance with claim 41, wherein said surface of said at least one lamella is structured exclusively in a region of a nozzle discharge opening.

44. The headbox in accordance with claim 43, wherein said surface is structured exclusively in a region of a lip of said nozzle discharge opening.

45. The headbox in accordance with claim 38, wherein the at least one structure is arranged at an angle of 0° to 90° to a machine direction.

46. The headbox in accordance with claim 45, wherein said at least one structure is arranged at an angle of 20° to 70° to the machine direction.

47. The headbox in accordance with claim 38, wherein said at least one structure comprises a curved structure arranged so that the suspension stream is tangentially aimed at said at least one structure in a machine direction and is subsequently diverted at an angle of 0° to 90°.

48. The headbox in accordance with claim 38, wherein said at least one lamella extends through a nozzle opening to outside of said headbox nozzle.

49. The headbox in accordance with claim 38, wherein said at least one structure has a length/width ratio (L/B)>2.

50. The headbox in accordance with claim 38, wherein said at least one lamella is structured continuously up to a lamella tip.

51. The headbox in accordance with claim 38, wherein said at least one lamella comprises at least two lamellae having sides arranged to face each other, and each of said facing sides comprise said structured surface.

52. The headbox in accordance with claim 51, wherein said at least one structures on the facing sides of the at least two lamellae are arranged to be oppositely oriented.

53. The headbox in accordance with claim 38, wherein said at least one structure comprises a recess formed in said at least one lamella.

54. The headbox in accordance with claim 38, wherein said at least one structure comprises a structure raised above said surface of said at least one lamella.

55. The headbox in accordance with claim 38, wherein said at least one structure comprises a curved flow guide element.

56. The headbox in accordance with claim 38, wherein said at least one structure is located inside said headbox nozzle.

57. The headbox in accordance with claim 38, wherein said at least one structure is located in a last third of said headbox nozzle viewed in a flow direction.

58. The headbox in accordance with claim 38, wherein said at least one structure comprises a plurality of structures arranged to generate flows running towards one another, thereby balancing one another.

59. The headbox in accordance with claim 38, wherein said headbox comprises a multi-layer headbox, and said structured surface is arranged to generate unidirectional flows.

60. The headbox in accordance with claim 38, wherein said headbox nozzle is delimited by at least one wall, and said at least one wall comprises a structured surfaces arranged to face the pulp suspension stream.

61. The headbox in accordance with claim 38, wherein said at least one lamella comprises at least two lamellae having sides arranged to face each other and each of the at least two lamellae includes a structured surface, and said structured surfaces are at least one of arranged to face each other with structures of said structured surfaces arranged to interlock or fit together or arranged on facing sides of one at least one of the lamella and a nozzle wall with structures of said structured surface and wall arranged to interlock or fit together.

62. The headbox in accordance with claim 38, wherein a depth of said at least one structure has a value in a range of 5% to 95% of a flow channel enclosed by said at least one lamella.

63. The headbox in accordance with claim 62, wherein said depth has a value in the range of 20% to 80% of the flow channel enclosed by said lamella.

64. The headbox in accordance with claim 38, wherein a depth of said at least one structure has a value in a range of 1% to 99% of a thickness of said at least one lamella.

65. The headbox in accordance with claim 64, wherein said depth has a value in the range of 10% to 95% of said lamella thickness.

66. The headbox in accordance with claim 38, wherein a height of said at least one structure has a value in the range of 1% to 99% of said flow channel enclosed by said at least one lamella.

67. The headbox in accordance with claim 66, wherein said height has a value in the range of 20% to 80% of the flow channel enclosed by said lamella.

68. The headbox in accordance with claim 38, wherein said structured surface comprises at least two structures separated by a partition, and said partition has a distance or thickness in a range of 0.5 mm to 20 mm, in which the partition range is at least one of constant or different in at least one of a machine and a cross machine direction.

69. The headbox in accordance with claim 68, wherein said partition distance or thickness is in the range of 2 mm to 10 mm.

70. The headbox in accordance with claim 38, wherein said headbox comprises a multi-layer headbox arranged to be charged with long-fibered material.

71. The headbox in accordance with claim 70, wherein a middle layer in said multi-layer headbox is charged with the long-fibered material.