EP1659214A1 - Headbox of a machine for manufacturing a fibrous web - Google Patents

Abstract

A papermaking assembly has a headbox that discharges a fibrous suspension through a horizontal array of tubes, each with a dilutant inlet, to an intermediate passage to a horizontal stacked array of rectangular passages. Each horizontal row of passages discharges to a single horizontal converging passage, each defined by a blade (10). One or more of the blades has a surface profile (13). The profile prevents or minimises mixing between the dilute (3) fluid fraction emerging from the vortex generator (5). The profile extends roughly the entire length of the blade as seen in the direction of flow.

Description

The invention relates to a headbox of a machine for producing a fibrous web, in particular paper or board web, from at least one pulp suspension, with a sectioned transversely to the machine direction dilution device, in particular Siebwasserdosierungseinrichtung, in the flow direction of at least one pulp suspension extending transversely to the machine direction intermediate channel, a a plurality of turbulence channels and having partial flow generating turbulence generator and then a headbox is connected downstream, which has a flow space and which is provided with a pulp suspension jet supplying exit gap.

Such a headbox is known for example from the European patent EP 0 857 816 B1. The respective blade used has a smooth surface on its two flow surfaces in a known manner. Through this respective smooth surface mixing of emerging from the turbulence generator and entering the headbox partial mixing streams is allowed to emerge from the exit slit of the headbox pulp suspension jet, and even promoted. As a result of this mixing of the partial mixing streams results in a correspondingly increased response width of the dilution water used. A regulation of narrow-wave disturbances in the fibrous web to be produced is thus no longer possible.

It is therefore an object of the invention to provide a headbox of the aforementioned types, which allows the use of a dilution water technology to achieve the narrowest possible response width of the dilution device.

This object is achieved in that the intermediate channel and / or the flow space of the headbox nozzle by at least one connected to the dilution device or with the turbulence generator by at least one lamella holder and two of at least one pulp suspension touched flow surfaces having fin is divided, that at least one of the two flow surfaces the at least one lamella having an at least partially structured surface is provided, wherein the structuring is preferably selected such that mixing of the partial mixing streams emerging from the dilution device and entering the intermediate channel or emerging from the turbulizer and entering the headbox nozzle is at least impeded, preferably nearly is completely prevented.

This inventive design of the headbox, in particular its fins, it is ensured that a mixing of the partial mixing streams in the region of the common intermediate channel or the common headbox nozzle is largely not possible. This achieves the narrowest possible response width of the dilution device with possible control of narrow-wave disturbances in the fibrous web to be produced.

In this case, the at least one flow area of the lamella is advantageously provided at least in the first tenth, preferably in the first fifth, in particular over its entire lamella length, with a corresponding structuring together with a structure length. Basically, the mixing of the The larger the structure length of the structuring, the better avoided is partial mixed flow.

Preferably, the structuring at an angle of -5 to + 5 °, preferably from -1 to + 1 °, in particular of 0 °, attached to the machine direction. In these areas, the flow quality and the orientation of the partial mixing streams are not yet adversely affected.

Furthermore, the structuring has a preferred pitch in the range of 5 to 100 mm, preferably 25 to 75 mm, wherein the respective pitch in the machine direction and / or transverse to the machine direction may be constant and / or different. These divisions essentially comprise the present-day divisions of a dilution device with its generated mixed partial flows. The division of the structuring is preferably geich or a fraction of the division of the dilution device. The structuring of the lamella and the sections of the dilution device are preferably arranged in the machine direction in the middle or approximately centrally offset from one another, so that a generated mixed partial flow passes through the lamella between two at least structurings.

For the structuring itself, at least one structure is preferably provided, which is formed by an elevation or by a depression.

If the structuring is carried out as an elevation, the structure assumes a structural height which is advantageously in the range of 5 to 250%, preferably 10 to 100%, in particular 25 to 50%, of the lamellar thickness. The structure height along the structure length can assume a constant, a decreasing or an increasing value.

If, however, the structuring is carried out as a depression, the structure assumes a structure depth which is advantageously in the range of 10 to 75%, preferably 25 to 50%, of the lamellar thickness. The structure depth along the structure length can again assume a constant value, a decreasing value or an increasing value.

The height of the structure can be further specified in relation to the flow channel formed between two fins with the appropriate channel height. Thus, the height of the structure may preferably assume a value in the range of 5 to 90%, preferably 25 to 75%, of the height of the flow channel.

Under flow and manufacturing aspects, the structure has a polygonal cross-section perpendicular to the structure length or flow direction of the pulp suspension. This can in particular be dome-shaped, semicircular, triangular, square, rectangular or pentagonal, this exemplary list is certainly not exhaustive.

Furthermore, the entire structure can also be formed from a large number of elevations and depressions. In this case, various structural patterns, for example zones with elevations, zones with depressions and mixing zones with elevations and depressions are possible. The zones may be arbitrarily arranged to form the texture pattern. In addition, the size of the individual zones may be the same and / or different.

Of course, the wall bounding the intermediate channel or the flow space of the headbox nozzle may also have a structured surface at least in some areas. With regard to the structuring, reference is made to the lamella structuring.

The inventive machine for producing a fibrous web, in particular paper and / or board web, is characterized in that it is provided with a head box according to the invention.

Further features and advantages of the invention will become apparent from the following description of preferred embodiments with reference to the drawings.

Figur 1

eine schematische, teilweise geschnittene Darstellung eines Stoffauflaufs einer Maschine zur Herstellung einer Faserstoffbahn;

Figuren 2a, 3a, 4a und 5a

vier erfindungsgemäße Lamellen mit zumindest bereichsweise unterseitig strukturierten Oberflächen in jeweiligen Ansichten entgegen der Strömungsrichtung der Faserstoffsuspension;

Figuren 2b, 3b, 4b und 5b

entsprechende Seitenansichten der erfindungsgemäßen Lamellen der Figuren 2a, 3a, 4a und 5a; und

Figur 6

zwei benachbarte erfindungsgemäße Lamellen in einer Ansicht entgegen der Strömungsrichtung der Faserstoffsuspension.

Show it

FIG. 1

a schematic, partially sectioned view of a headbox of a machine for producing a fibrous web;

Figures 2a, 3a, 4a and 5a

four lamellae according to the invention with surfaces structured at least in some areas on the underside in respective views opposite to the direction of flow of the pulp suspension;

Figures 2b, 3b, 4b and 5b

corresponding side views of the slats according to the invention of Figures 2a, 3a, 4a and 5a; and

FIG. 6

two adjacent lamellae according to the invention in a view opposite to the flow direction of the pulp suspension.

1 shows a schematic, partially sectioned illustration of a headbox 1 for a machine for producing a fibrous web from a pulp suspension 2 (Q _H , C _H ). The machine may be a paper or board machine and the fibrous web may be a paper or board web. The headbox 1 in deviation from the illustrated straight design to have an at least simple kinked construction. Such at least simply kinked headboxes were and are by Applicant manufactured. The buckling may for example be between the intermediate chamber and the turbulence generator.

The headbox 1 comprises a transverse to the machine direction L (arrow) sectioned dilution device 3, in particular Siebwasserdosierungseinrichtung (Q _L , C _L ), in the flow direction S (arrow) of the at least one pulp suspension 2 in a direction transverse to the machine direction L (arrow) extending intermediate channel 4, a plurality of turbulence channels 6 aufwei transmitter turbulence generator 5 and then a headbox nozzle 7 is connected downstream. The headbox nozzle 7 has a flow space 8 and is provided with a pulp suspension jet 12 supplying exit slit 11.

By way of example, the dilution device 3 may be a known white water metering system, as provided in connection with the ModuleJet® headbox available on the market. The ModuleJet® headbox is described for example in German Patent DE 40 19 593 C2. It is only important that the dilution device 3 delivers partial mixed flows M _T with different consistency and a certain mixing width into the intermediate channel 4.

Furthermore, the turbulence generator 5 may be provided in particular as a turbulence insert. The turbulence channels 6 can be formed in particular by turbulence pipes.

The lamella 10 now has, as detailed in the further FIGS. 2a to 5a and 2b to 5b, at least one region-wise structured surface 13 ', 13 on at least one of its two flow surfaces F _O , F _U , F _O ', F _U ' on. The structuring of the surface 13, 13 'is preferably chosen such that a mixture of emerging from the turbulence generator 5 and in the Headbox 7 entering partial mixing streams M _T at least difficult, preferably almost completely prevented.

The intermediate channel 4 and the flow space 8 of the headbox nozzle 7 is now by at least one of the dilution device 3 and the turbulence generator 5 by means of at least one blade holder 9 ', 9 connected and two of at least one pulp suspension 2 touched flow surfaces F _O , F _U , F _O ', F _U ' having lamella 10, 10 'divided. At least one of the two flow surfaces F _O , F _U , F _O ', F _U ' of the at least one lamella 10, 10 'is provided with an at least partially structured surface 13, 13', wherein the structuring is preferably selected such that a Mixing of emerging from the dilution device 3 and entering the intermediate channel 4 or emerging from the turbulence generator 5 and entering the headbox 7 partial mixing streams M _T at least difficult, preferably almost completely prevented. The lamellae 10, 10 'can have different contours and lengths.

It is obvious to the person skilled in the art that only the intermediate chamber 4 or the flow space 8 of the headbox nozzle 7 can be provided with at least one lamella 10, 10 '. If both spaces 4, 8 are provided with lamellae 10, 10 ', they may, as already stated, be different in terms of number, contour, length and the like.

The dilution device 3 may, of course, have a plurality of channels in a further embodiment, between which the lamella holders are then arranged.

The lamella holder 9, 9 'for holding the respective lamella 10, 10' can be embodied, for example, according to the disclosure of the German published patent application DE 199 62 709 A1. The lamella holder 9, 9 'can be hinged be formed to thereby allow an articulated mounting of the lamella 10, 10 ', or it may be rigid, thereby allowing a firm clamping of a preferably kinked lamella. Also, the lamellae holder 9, 9 'sectioned transversely to the machine direction, preferably formed uniformly sectioned and the lamella 10, 10' may have in the region of the lamella holder 9, 9 'an inflow surface with streamlined contour with and without special surface structure.

FIGS. 2 a to 5 a now each show a lamella 10, 10 'according to the invention with at least one surface 13, 13' structurally structured on the underside in respective views opposite to the flow direction S (arrow) of the pulp suspension 2.

In the embodiment of FIG. 2a, the structuring is applied to the surface 13, 13 'of the lower flow surface F _U , F _U '. For structuring at least one structure 14 is provided, which is formed by a survey 15. The structuring has four different structures 14.1 to 14.4, these having different polygonal cross-sections. The structure 14.1 has, for example, a rectangular cross section, the structure 14.2 has a rounded rectangular, the structure 14.3 has a dome-shaped and finally the structure 14.4 has a triangular shape. These structures 14 are merely exemplary in nature. In Realisierun gsfall probably only a structure 14 for structuring the surface 13, 13 'of the lamella 10, 10' are used.

The structure 14 assumes a structure height H, which is preferably in the range from 5 to 250%, preferably from 10 to 100%, in particular from 25 to 50%, of the lamella thickness D. Furthermore, the structure height H takes in the flow direction S (arrow) of the pulp suspension 2 a constant value, as in Figure 2b, the inventive lamella 10, 10 'of Figure 2a in a Side view represents, it can be seen. However, the structure height H can also assume a decreasing or increasing value in the flow direction S (arrow) of the pulp suspension 2.

In the embodiment of FIG. 3a, the structuring is in turn attached to the surface 13, 13 'of the lower flow surface F _U , F _U '. For structuring at least one structure 14 is provided, which however is formed by a recess 16. The structuring has four different structures 14.5 to 14.8, these having different polygonal cross sections. The structure 14.5 has, for example, a rectangular cross section, the structure 14.6 a rounded rectangular, the structure 14.7 a dome-shaped and finally the structure 14.8 a triangular. These structures 14 are merely exemplary in nature. In the realization case, only a structure 14 for the structuring of the surface 13, 13 'of the lamella 10, 10' will probably be used.

As can be seen in FIGS. 2a to 5b, the lamella 10, 10 'may have an at least substantially rectilinear course and may have different geometries and / or structures, in particular in the fin end regions. Moreover, the lamella 10, 10 'preferably consists of a CFRP, GFRP, polycarbonate such as Makrolon® or Lexan®, high performance polymer such as polyphenylsulfone, polyethersulfone, polyetherimide or polysulfone and / or the like.

In the embodiment of Figure 4a, the structuring is applied both to the surface 13, 13 'of the lower flow surface F _U , F _U ' and at least partially to the surface 13, 13 'of the upper flow surface F _O , F _O '. The structures 14 provided for structuring are all in the form of recesses 16. The opposing structures 14.9a, 14.9b and 14.10a, 14.10b have a flat rectangular and rounded cross-section and the only underside mounted structures 14.11, 14.12, 14.13 a deep rectangular and rounded cross-section.

And in the embodiment of Figure 5a, the structuring is again applied both to the surface 13, 13 'of the lower flow surface F _U , F _U ' and to the surface 13, 13 'of the upper flow surface F _O , F _O ' is introduced. The structures 14 provided for the structuring are formed both as elevations 15 and depressions 16, the elevations 15 and the depressions 16 alternating in their arrangement transversely to the flow direction S (arrow). Each of the depressions 16 forming structures 14.14 have a flat rectangular and rounded cross-section and each one elevation 15 forming structures 14.15 a triangular cross-section. The structure 14 is thus formed from a total of a plurality of elevations 15 and depressions 16.

The respective structuring on the two surfaces 13, 13 'of the lower flow surfaces F _U , F _U ' and / or the upper flow surfaces F _O , F _O 'need not necessarily be the same (see FIG. 4a). The patterning structures 14 may be different in size, location, pitch, and the like.

FIG. 6 shows, for example, two adjacent lamellae 10, 10 'according to the invention in a view opposite to the flow direction S (arrow) of the pulp suspension 2. It can be clearly seen that the structures 14 of the two surfaces 13, 13 'of the lower flow surfaces F _U , F _U ' and the upper flow surfaces F _O , F _O 'are different in size, formation and pitch and offset from each other.

FIGS. 2 b, 3 b, 4 b and 5 b illustrate the lamellae 10, 10 'according to the invention of FIGS. 2 a, 3 a, 4 a and 5 a in a respective side view.

Further, according to the embodiment of FIG. 2b, the at least one flow surface F _O , F _O ', F _U , F _U ' of the lamella 10, 10 'of FIGS. 2a to 5b is at least in the first tenth, preferably in the first fifth, in particular over their entire length Lamella length _{L L} , provided with a corresponding structuring along with structure length II. The lamella 10, 10 'generally has a L ength amellenl l _L in the range of 100 to 800 mm and preferably ends within the headbox nozzle. 7

The structuring itself is at an angle α of -5 to + 5 °, preferably from -1 to + 1 °, in particular of 0 °, attached to the machine direction L.

According to the embodiment of FIG. 4a, the structuring has a pitch T _S in the range of 5 to 100 mm, preferably 25 to 75 mm, the respective pitch T _SN in the machine direction L (arrow) and / or transversely to the machine direction L (FIG. Arrow) is constant and / or different. The dilution device 3 has a pitch T _V (FIG. 1), wherein the pitch T _{S of} the structuring is the same or a fraction, in particular ½, ⅓ or ¼, of the pitch T _{V of} the dilution device 3. The structuring of the blade 10 ', 10 and the sections of the dilution device 3 in the machine direction L (arrow) are arranged centrally or approximately centrally offset from one another.

Furthermore, it can be provided in all embodiments that also the intermediate channel 4 and the flow chamber 8 of the headbox 7 limiting wall at least partially a structured surface 13 ', 13 has.

In summary, it should be noted that the invention provides one of the aforementioned type which, when using a dilution water technique, makes it possible to achieve the narrowest possible response width of the dilution device.

LIST OF REFERENCE NUMBERS

1

headbox

2

Fibrous suspension

3

Dilution device, white water dosing device

4

intermediate channel

5

turbulence generator

6

turbulence channel

7

headbox

8th

flow chamber

9; 9 '

slat supporting

10; 10 '

lamella

11

exit slit

12

Fibrous suspension beam

13; 13 '

surface

14

structure

14.1 to 14.4

structure

14.5 to 14.8

structure

14.9a, 14.9b

structure

14.10a, 14.10b

structure

14.11, 14.12, 14.13

structure

14:14

structure

14:15

structure

15

survey

16

deepening

D

lamella thickness

F _O ; F _O '

Upper flow area

F _U ; F _U '

Lower flow area

H

structure height

L

Machine direction (arrow)

l _L

lamellar length

l _s

structure length

M _T

Part mixed stream

S

Flow direction (arrow)

T _S

division

T _SN

division

T _V

division

α

corner

Claims (17)

Headbox (1) of a machine for producing a fibrous web, in particular paper or board web, from at least one pulp suspension (2), with a transverse to the machine direction (L) sectioned dilution device (3), in particular Siebwasserdosierungseinrichtung, in the flow direction (S) of at least a fibrous suspension (2) extending transversely to the machine direction (L) extending intermediate channel (4), a plurality of turbulence channels (6) and partial mixing streams (M _T ) generating turbulence generator (5) and then a headbox (7) is connected downstream, the a flow space (8) and which is provided with a pulp suspension jet (12) delivering exit slit (11),
characterized,
in that the intermediate channel (4) and / or the flow space (8) of the headbox nozzle (7) are connected by at least one to the dilution device (3) or to the turbulence generator (5) by means of at least one lamella holder (9 '; a lamella (10 ', 10) having flow surfaces (F _O ', F _U ', F _O , F _U ) is subdivided into a pulp suspension (2),
that at least one of the two flow surfaces (F _o ', F _u'; F _o, F _u) of the at least one blade (10 '; 10) having an at least partially structured surface (13'; 13) is provided,
wherein the structuring is preferably selected such that a mixing of the partial mixing streams (M _T ) emerging from the dilution device (3) and entering the intermediate channel (4) or emerging from the turbulence generator (5) and entering the headbox nozzle (7) is at least made more difficult , preferably almost completely prevented. Headbox (1) according to claim 1,
characterized,
in that both flow surfaces (F _O ', F _U ', F _O , F _U ) of the lamellae (10 ', 10) are provided with a surface (13', 13) which is structured at least in regions. Headbox (1) according to claim 1 or 2,
characterized,
that the at least one flow surface (F _O ', F _U ', F _O , F _U ) of the lamella (10 ', 10) at least in the first tenth, preferably in the first fifth, in particular over its entire lamella length (l _L ) with a corresponding structure including structure length (l _S ) is provided. Headbox (1) according to one of the preceding claims,
characterized,
that the structuring at an angle (α) of -5 to + 5 °, preferably of -1 to + 1 °, in particular from 0 ° to the machine running direction (L) is attached. Headbox (1) according to one of the preceding claims,
characterized,
that the structuring (T _S) has a pitch in the range of 5 to 100 mm, preferably from 25 to 75 mm, the respective pitch (T _SN) in the machine direction (L) and / or transverse to the machine direction (L) is constant and / or different. Headbox (1) according to claim 5,
characterized,
in that the dilution device (3) has a graduation (T _V ), wherein the graduation (T _S ) of the structuring is equal to or a fraction of the graduation (T _V ) of the dilution device (3). Headbox (1) according to claim 6,
characterized,
that the structuring of the lamella (10 '; 10) and the sections of the dilution device (3) in the machine running direction (L) are arranged offset centrally or approximately centrally each other. Headbox (1) according to one of the preceding claims,
characterized,
in that at least one structure (14; 14.1, 14.2, 14.3, 14.4; 14.15) is provided, which is formed by an elevation (15). Headbox (1) according to claim 8,
characterized,
that the structure (14; 14.1, 14.2, 14.3, 14.4; 14:15) has a structure height (H) assumes that (in the range from 5 to 250%, preferably from 10 to 100%, particularly from 25 to 50%, of the lamellae thickness D ) lies. Headbox (1) according to claim 9,
characterized,
that the structure height (H) along the structure length (l _S) a constant, a decreasing or an increasing value takes. Headbox (1) according to one of claims 1 to 7,
characterized,
is provided which is formed by a recess (16) that at least one structure (14:14 14; 14.5, 14.6, 14.6, 14.8;; 14.9a, 14.9b, 14.10a, 14.10b, 11.14, 14.12, 14:13). Headbox (1) according to claim 11,
characterized,
that the structure (14; 14.5, 14.6, 14.6, 14.8; 14.9a, 14.9b, 14.10a, 14.10b, 11.14, 14.12, 14:13; 14:14) has a structure depth (T) assumes in the range of 10 to 75%, preferably from 25 to 50%, the lamella thickness (D) is. Headbox (1) according to claim 12,
characterized,
that the structure depth (T) along the structure length (l _S) a constant, a decreasing or an increasing value takes. Headbox (1) according to one of claims 8 to 13,
characterized,
that the structure (14; 14.1, 14.2, 14.3, 14.4, 14.5, 14.6, 14.6, 14.8; 14.9a, 14.9b, 14.10a, 14.10b, 11.14, 14.12, 14:13, 14:14, 14:15) has a polygonal cross section, in particular a dome-shaped, a semicircular, a triangular, a square, a rectangular or a pentagonal cross-section, having. Headbox (1) according to one of claims 8 to 14,
characterized,
that the structure (14, 14.1, 14.2, 14.3, 14.4, 14.5, 14.6, 14.6, 14.8, 14.9a, 14.9b, 14.10a, 14.10b, 14.11, 14.12, 14.13, 14.14, 14.15) in total from a variety of surveys (15) and recesses (16) is formed. Headbox (1) according to one of the preceding claims,
characterized,
that the wall defining the intermediate channel (4) or the flow space (8) of the headbox nozzle (7) also has a structured surface (13 ', 13) at least in regions. Machine for producing a fibrous web, in particular paper and / or board web, with a headbox (1) according to one of claims 1 to 16.

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