EP1318230A1 - Headbox - Google Patents

Abstract

The stock inlet (12) for a papermaking machine, and especially a multi-layer stock inlet, has an outflow jet (10) with at least one blade (16) dividing its interior zone (14). The blade is hollow, to pump (20) a dosed medium (18) into the fiber suspension, and especially under a pressure which differs from the pressure around the blade. The hollow blade is mounted at the turbulence block (24) of the stock inlet. The pumped medium can be recovered water from the web drying stages, glue, starch, fine or bulking matter, auxiliary materials, dye, and the like.

Description

The invention relates to a headbox, in particular a multilayer headbox, a paper machine, with a nozzle, the interior of which at least in some areas is divided by at least one lamella.

Such headboxes are for example from DE 199 02 621 A1 and WO 82/03413 A1 known.

In general, headboxes with and without fixed or flexible fins are between the layers of fabric and / or the rows of diffusers or turbulence generators known. The fins cause an increase in microturbulence, one Layer separation, a reduction in the tear length ratio and / or Reduction of so-called "tiger stripes" (compare, for example, DE 199 02 621 A1).

WO 82/03413 A1 already discloses a layer separation by means of a machine-wide multiple nozzle and the feed of primarily white water known in the machine-wide middle class. In this publication is the feeding of fine or fillers by means of this middle layer is also mentioned. By separating the machine-wide middle class from the other machine-wide layers by means of short lamellas, the pressures in the machine-wide outer layers and in the machine-wide middle layer be at least essentially the same (necessary gap between lamella and Nozzle wall). The machine-wide multiple nozzle also enables one Pressure equalization in the different layers in the cross machine direction.

When it comes to starch sizing of paper, it is mass sizing and surface sizing known.

In connection with the admixture of auxiliaries and fillers is common a dosage in the mass or, especially for auxiliary substances, in the constant Part provided.

The aim of the invention is to provide an improved headbox of the type mentioned Way of creating. The setting options in particular should also be considered a range of operating parameters such as the degree of mixing inside and outside the nozzle, mixing in the z direction, the turbulence that arises in the suspension, the transverse profiling and so on to be expanded further.

According to the invention, this object is achieved by a headbox, in particular Multilayer headbox, a paper machine, with a nozzle, the interior of which is divided at least in regions by at least one lamella, wherein at least one slat is designed as a hollow slat, preferably for metering a pumpable medium in the suspension in particular with a region of the nozzle space surrounded by the pressure in the hollow lamella different pressure can be applied.

It is therefore particularly possible to use one or more hollow lamellas pumpable medium, such as white water, glue or starch liquor, Fine or fillers, auxiliaries, color and so on, with or without fiber content, for example in the nozzle area. By using a Hollow slats are clear pressure differences between the slat interior and the nozzle area surrounding the lamella possible. This results in, among other things the possibility of admixing the pumpable medium at a rate, the slower, the same quick or faster than that in the area of Dosing point is the prevailing suspension speed. To the specified The hollow lamella should preferably be able to perform its function as optimally as possible be stable in thickness, the thickness of the hollow lamella being at most half as large like the two neighboring nozzle heights to avoid excessive convergence, to avoid excessive heights, to avoid too large beam lengths and to improve the paper quality (formation and the like) should be. For example, to high speed differences allow and avoid bulging of the slat, the hollow slat should expediently both in the flow direction and in the transverse direction be very rigid. A rigid hollow slat also allows different Press in the part above and below.

By choosing the hollow slat length and the speed ratio Exit rate / suspension rate can be the degree of mixing can be set in and outside the nozzle. By appropriate Design is achieved, among other things, that the pumpable medium is mixed with the residual material in the area of the initial drainage, preferably with long hollow lamella length and therefore short jet.

By appropriate dosing using the hollow lamella and in particular via a corresponding speed difference and the position of the slat tip compared to the nozzle geometry, the mixing in the z direction be adjusted well.

Despite the addition of dosing agents of the type described between the suspension layers of a multilayer headbox, the layers remain through the Use of one or more hollow slats as the respective dosing unit as far as possible Cut. The separation can be maintained up to the forming unit, for example become. This makes it known for multi-layer headboxes Mixing is reduced and the coverage or layer purity significantly increased.

For example, by adding starch between two layers and one Appropriate control of the mixing will be the strengths, for example those in the z direction, specifically increased. The plucking and dusting in the The dryer section becomes more manageable.

The depletion of fine materials in the middle of the blade, which is generally known in gap formers, viewed in the z-direction, the addition of fine substances between the two layers are counteracted.

In addition, with a corresponding speed difference desired turbulence can be introduced into the fiber suspension in order to for example the strength properties in the longitudinal and transverse directions (L / Q ratio) to change.

The hollow lamella can, in particular, start in the direction of flow considered entry-side end in the nozzle space. The can Hollow lamella with the relevant end, for example in a headbox block such as in particular a turbulence block.

In certain cases it is advantageous if the hollow lamella is inside the nozzle area ends. The hollow lamella can be, for example, in the area of the nozzle outlet gap and preferably end exactly at this outlet gap. In principle, however, the hollow slat can also be used at other points within the End of the nozzle area.

In other cases it may be advantageous if the cavity lamella is outside of the nozzle area ends.

In a preferred practical embodiment of the invention Headbox, the hollow lamella comprises at least two generally in the direction of flow extending over at least part of the slat length Walls which can serve, in particular, separate pressure rooms to accomplish. The hollow lamella preferably comprises at least two opposite side walls. These slat walls are preferred non-positively connected.

In an expedient practical embodiment are between the two One or more partitions are provided to different, to form channels extending in the direction of flow.

The walls generally extending in the direction of flow can according to an expedient embodiment can be at least partially formed by that one or. in the hollow lamella, which is otherwise made of solid material several channels or tubes are formed or incorporated.

As already mentioned, the hollow lamella is preferably both in the direction of flow and also rigid in the transverse direction. The slat cover can and / or the slat bottom, for example with ribs or the like be reinforced. The risk of bulging the hollow lamella is thus reduced Minimum reduced.

In an advantageous expedient embodiment of the invention The headbox is the interior of the hollow slat in the area of the free slat end trained converging.

In certain cases, however, it can also be advantageous if the interior the hollow slat in the area of the free slat end at least upwards and is limited at the bottom by mutually parallel walls.

The interior of the hollow slat can be in the area of the free slat end also be divergent. So can the interior of the hollow slat expand step-by-step in the area of the free slat end, for example.

It is also advantageous if the interior of the hollow lamella at least in the area the free slat end is structured. In principle, however, this is also the case Execution conceivable in which the interior of the hollow slat at least in Area of the free slat end is not structured.

According to a preferred practical embodiment of the invention Headbox are provided by means of the hollow lamella as pumpable Medium for example white water, glue or starch liquor, fine or fillers, Auxiliaries, paint and / or the like can be metered into the nozzle space.

The hollow lamella is advantageously for metering a pumpable one Medium in the nozzle space can be pressurized to a higher, equal or is lower than the pressure at the dosing point in the surrounding of the hollow lamella Area.

The hollow lamella comprises several, each extending in the direction of flow Channels, at least these channels can be used for cross-profiling can be partially charged separately.

So become one or more hollow lamellas with themselves in the direction of flow extending channels used, the dosage of the relevant pumpable medium in the cross machine direction. The to be dosed Means can therefore be distributed over the machine width as required.

In an expedient embodiment of the headbox according to the invention are at least partially separate dosing units for the different channels such as especially associated with control valves and / or the like.

The metering can thus be carried out via the various channels and, for example, control valves, similar to the commercially available "ModuleJet" version, or influenced by several independent dosing units across the web width become.

Slats can in principle also in the specified manner as Hollow slats are formed, for example, to have a certain bending stiffness to achieve or to save material, for example. Pumpable dosage In this case, medium is not mandatory.

Figur 1:

eine schematische Längsschnittdarstellung eines die Düse umfassenden Teils eines Stoffauflaufs;

Figur 2:

eine schematische Draufsicht der in der Figur 1 gezeigten Hohllamelle;

Figuren 3 bis 7:

schematische Teilquerschnittsdarstellungen verschiedener Ausführungsformen der Hohllamelle mit Kanälen unterschiedlichen Querschnitts, geschnitten entlang der Linie A-A in der Figur 2;

Figur 8:

eine schematische Teilquerschnittsdarstellung einer Hohllamelle, deren Deckel und Boden durch Rippen verstärkt sind;

Figur 9:

eine schematische Längsschnittdarstellung eines Teils einer Hohllamelle, deren Innenraum im Bereich des freien Lamellenendes konvergierend ausgebildet ist;

Figur 10:

eine schematische Längsschnittdarstellung eines Teils einer Hohllamelle, deren Innenraum im Bereich des freien Lamellenendes zumindest nach oben und nach unten durch zueinander parallele Wandungen begrenzt ist;

Figur 11:

eine schematische Längsschnittdarstellung eines Teils einer Hohllamelle, deren Innenraum im Bereich des freien Lamellenendes divergierend ausgebildet ist;

Figur 12:

eine schematische Längsschnittdarstellung eines Teils einer Hohllamelle, deren Innenraum sich im Bereich des freien Lamellenendes stufenartig erweitert; und

Figur 13:

eine schematische, teilweise geschnittene Draufsicht eines mit zumindest einer Hohllamelle versehenen Stoffauflaufs mit einer Querprofilregelung.

The invention is explained in more detail below on the basis of exemplary embodiments with reference to the drawings; in this show:

Figure 1:

is a schematic longitudinal sectional view of a part of a headbox comprising the nozzle;

Figure 2:

a schematic plan view of the hollow lamella shown in Figure 1;

Figures 3 to 7:

schematic partial cross-sectional representations of different embodiments of the hollow lamella with channels of different cross-section, cut along the line AA in FIG. 2;

Figure 8:

a schematic partial cross-sectional view of a hollow lamella, the lid and bottom of which are reinforced by ribs;

Figure 9:

a schematic longitudinal sectional view of part of a hollow lamella, the interior of which is designed to converge in the region of the free lamella end;

Figure 10:

is a schematic longitudinal sectional view of a part of a hollow lamella, the interior of which is bounded in the area of the free lamella end at least upwards and downwards by mutually parallel walls;

Figure 11:

is a schematic longitudinal sectional view of part of a hollow lamella, the interior of which is designed to diverge in the region of the free lamella end;

Figure 12:

is a schematic longitudinal sectional view of part of a hollow lamella, the interior of which widens in steps in the area of the free lamella end; and

Figure 13:

is a schematic, partially sectioned plan view of a headbox provided with at least one hollow lamella with a cross profile control.

FIG. 1 shows a schematic longitudinal sectional view of the nozzle 10 comprehensive part of a headbox 12 of a paper machine. It can are in particular a multi-layer headbox.

The interior 14 of the nozzle 10 is at least partially by at least a hollow slat 16 divided. This hollow lamella 16 is preferably for metering a pumpable medium 18 in the suspension in particular with a region of the nozzle space surrounded by the pressure in the hollow lamella 16 14 different pressures can be applied. The hollow lamella 16 ends as follows If, for example, inside the nozzle chamber 14, the metering takes place of the pumpable medium 18 in this nozzle space 14. According to FIG the medium 18 in question is fed to the hollow lamella 16 via a pump 20 become.

Through the hollow lamella 16, the suspension layers A and B are separated from one another Cut. The pumpable medium 18 is therefore between these two layers A, B dosed.

The hollow lamella 16 extends from viewed in the flow direction S. inlet-side nozzle end 22 in the nozzle chamber 14. In the present case is the hollow lamella 16 with its relevant end 16 'in a headbox block such as in particular a turbulence block 24.

While the hollow lamella 16 in the illustrated embodiment within of the nozzle chamber 14 ends, such designs are basically also, for example conceivable, in which the hollow lamella 16 in the region of the nozzle outlet gap 26 and preferably exactly at this nozzle outlet gap 26 or outside of the nozzle chamber 14 ends.

The hollow slat 16 is down and up through a bottom 16 "respectively Cover 16 '' 'limited.

Furthermore, the hollow lamella 16 is of stable thickness, the thickness D of the hollow lamella 16 being at most half as large as the two adjacent nozzle heights H ₁ , H ₂ .

FIG. 2 shows a schematic top view of the hollow lamella 16.

As can be seen from this figure 2, the hollow lamella 16 can at least comprise two opposite side walls 28, 30. How in particular from Figures 3 to 7, can between these two side walls 28, 30 one or more partition walls 32 may be provided. These walls can in particular serve to differentiate each in the direction of flow S extending channels 34 (compare in particular Figures 3 to 7) form. Through the walls in question can thus in particular from each other separate pressure rooms are created.

In the embodiments according to FIGS. 3 to 7, they are generally in Flow direction S extending walls 28 - 32 (see also the figures 1 and 2) at least partially formed by the fact that in the rest of solid material existing hollow lamella 16 one or more channels 34 or tubes are trained or incorporated.

In the embodiment according to FIG. 3, the channels 34 each have a square, preferably square cross section. According to Figure 4 can these channels 34 also have, for example, a triangular cross section. In the embodiment according to FIG. 5, the channels have a round one Cross-section. The cross section of the channels 34 of the embodiment shown in FIG. 6 corresponds, for example, to a hexagon. The channels 34 of the embodiment 7 again have a square, preferably square cross section. In this case, two corners face the respective channels 34 up and down and two corners to the two opposite each other Pages. This results in a corresponding partition 32 a variable thickness, which from time to time viewed from top to bottom then increases again. In contrast, the partitions at Embodiment according to FIG 3 a constant from top to bottom Thickness.

The hollow lamella 16 is preferably both in the flow direction S and in Transverse direction rigid. In Figure 8 is a schematic partial cross-sectional view for example, a hollow lamella 16 shown, the bottom 16 "and cover 16" 'are each reinforced by ribs 36. The representation corresponds again a section along the line A-A in FIG. 2.

FIG. 9 shows a schematic longitudinal sectional illustration of part of a Hollow lamella 16, the interior 14 in the area of the free lamella end 38 for Example is designed in the manner of a nozzle converging. Is shown here just as in FIGS. 10 to 12, a section along the line B-B in FIG. 2.

In the embodiment according to FIG. 10, the interior 14 is the hollow lamella 16 in the area of the free slat end 38 at least upwards and bounded downwards by mutually parallel walls 40, 42. These walls or wall sections 40, 42 are in the present case Part of the slat cover 16 '' 'or slat bottom 16 ".

In the embodiment according to FIG. 11, the interior 14 is the hollow lamella 16 formed diverging in the area of the free fin end 38.

FIG. 12 shows a representation comparable to that in FIGS. 9 to 11 an embodiment in which the interior 14 of the hollow lamella 16 in the area of the free slat end 38 expanded in steps.

In the area of the free fin end 38, that is to say in the area of the tip the hollow lamella 16 may or may not be structured.

Means can be provided through which the hollow lamella 16 can be pumped Means 18 for example white water, glue or starch liquor, fine or Fillers, auxiliaries, paint and / or the like in the suspension respectively can be metered into the nozzle chamber 14.

The hollow lamella 16 is preferably for metering a respective pumpable one Medium 18 in the suspension or in the nozzle chamber 14 with a Pressurizable that is higher, equal or lower than the pressure at the Dosing point in the area surrounding the hollow lamella 16. As already mentioned, This dosing point can be inside or outside the nozzle chamber 14.

In the event that the hollow lamella 16 several each in the flow direction S extending channels 34, these channels 34 can in particular for a Cross-profiling or cross-profile control at least partially separated be acted upon. The various channels 34 can at least partially separate dosing units such as in particular control valves and / or the like be assigned.

FIG. 13 shows a schematic, partially sectioned top view of one with at least one hollow slat 16 provided with a headbox 12 with a cross profile control, for which a control or regulating device 44 in the present case such as in particular a PC and a cross-profile measuring device 46 are. The dosage can then depend on the measured values and corresponding ones Setpoints take place.

The hollow lamella 16 is in particular again supported in a turbulence block 24, which can in particular be a turbulence generator.

LIST OF REFERENCE NUMBERS

10

jet

12

headbox

14

nozzle chamber

16

hollow blade

16 '

lamella end

16 "

slat floor

16 " '

slats cover

18

Pumpable medium

20

pump

22

Inlet nozzle end

24

turbulence block

26

Nozzle exit gap

28

Side wall

30

Side wall

32

partition wall

34

channel

36

rib

38

Free slat end

40

wall

42

wall

44

Control or regulating device, PC

46

Transverse profile measuring device

D

thickness

H ₁ , H ₂

nozzle height

Claims (23)

Headbox (12), in particular multi-layer headbox, of a paper machine, with a nozzle (10), the interior (14) of which at least in some areas is divided by at least one lamella (16), at least a lamella is designed as a hollow lamella (16), preferably for metering a pumpable medium (18) in the suspension in particular with an area of the nozzle space surrounded by the pressure in the hollow lamella (16) (14) different pressure can be applied. Headbox according to claim 1,
characterized in that the hollow lamella (16) extends from the nozzle end (22) on the inlet side, viewed in the direction of flow (S), into the nozzle chamber (14). Headbox according to claim 2,
characterized in that the hollow lamella (16) is supported at one end (16 ') in a headbox block (24). Headbox according to claim 2 or 3,
characterized in that the hollow lamella (16) ends within the nozzle space (14). Headbox according to claim 2 or 3,
characterized in that the hollow lamella (16) ends in the region of the nozzle outlet gap (26) and preferably exactly at this nozzle outlet gap (26). Headbox according to claim 2 or 3,
characterized in that the hollow lamella (16) ends outside the nozzle space (14). Headbox according to one of the preceding claims,
characterized in that the hollow lamella (16) comprises at least two walls (28-32) which generally extend in the flow direction (S) over at least part of the lamella length, in order in particular to create pressure spaces (34) which are separate from one another. Headbox according to claim 7,
characterized in that the hollow lamella (16) comprises at least two opposite side walls (28, 30). Headbox according to claim 8,
characterized in that one or more partition walls (32) are provided between the two side walls (28, 30) in order to form different channels (34) each extending in the flow direction (S). Headbox according to one of claims 7 to 9,
characterized in that the walls (28-32) which generally extend in the direction of flow (S) are at least partially formed by the fact that one or more channels (34) or tubes are formed or incorporated in the hollow lamella (16), which is otherwise made of solid material , Headbox according to one of the preceding claims,
characterized in that the hollow lamella (16) is of stable thickness, the thickness (D) of the hollow lamella (16) being at most half the size of the two adjacent nozzle heights (H ₁ , H ₂ ). Headbox according to one of the preceding claims,
characterized in that the hollow lamella (16) is designed to be rigid both in the direction of flow (S) and in the transverse direction. Headbox according to one of the preceding claims,
characterized in that the slat cover (16 "') and / or the slat bottom (16") are reinforced with ribs (36) or the like. Headbox according to one of the preceding claims,
characterized in that the interior (14) of the hollow lamella (16) is designed to converge in the region of the free lamella end (38). Headbox according to one of claims 1 to 13,
characterized in that the interior (14) of the hollow slat (16) in the area of the free slat end (38) is delimited at least upwards and downwards by walls (40, 42) which are parallel to one another. Headbox according to one of claims 1 to 13,
characterized in that the interior (14) of the hollow lamella (16) is designed to diverge in the region of the free lamella end (38). Headbox according to one of the preceding claims,
characterized in that the interior (14) of the hollow lamella (16) widens in steps in the region of the free lamella end (38). Headbox according to one of the preceding claims,
characterized in that the interior (14) of the hollow lamella (16) is structured at least in the region of the free lamella end (38). Headbox according to one of claims 1 to 17,
characterized in that the interior (14) of the hollow lamella (16) is not structured at least in the region of the free lamella end (38). Headbox according to one of the preceding claims,
characterized in that means are provided through which white water, glue or starch liquor, fine or fillers, auxiliaries, paint and / or the like can be metered into the suspension via the hollow lamella (16) as a pumpable medium (18). Headbox according to one of the preceding claims,
characterized in that the hollow lamella (16) for metering a respective pumpable medium (18) into the suspension can be subjected to a pressure which is higher, equal or lower than the pressure at the dosing point in the area surrounding the hollow lamella (16). Headbox according to one of the preceding claims,
characterized in that the hollow lamella (16) comprises a plurality of channels (34) each extending in the flow direction (S) and that these channels (34) can be acted on at least partially separately, in particular for cross-profiling. Headbox according to claim 22,
characterized in that the different channels (34) are assigned at least partially separate dosing units, such as in particular control valves and / or the like.

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