EP1342835B1 - Headbox - Google Patents

Abstract

The stock inlet (10), for a papermaking machine, has a central component group (22) for the pulp delivery jet (12) with a lower carrier plate (20) forming a lower arm structure, and a parallel upper arm (24). Two central sections (26,28) are in succession in the machine running direction (L). The upper arm and the trailing center section (28) are each segmented across the machine running direction. The first center section (26) and the lower jet wall (14) have an unbroken run across the machine running direction. The lower jet wall slides on the static lower carrier plate, which is preferably segmented. The upper jet wall (16) swings on a hinge (18) with its axis (A) across the machine line.

Description

The invention relates to a headbox for a paper machine with a nozzle extending transversely to the machine direction over the machine width according to the preamble of claim 1.

In the usual headboxes of the type mentioned above, the lower nozzle wall is usually supported via an intended as a continuous welded construction inlet table. In particular, due to the influence of the thermal expansion due to the material temperature, however, deviations from the desired parallelism of the outlet gap can occur.

The aim of the invention is to provide a headbox of the type mentioned above, which ensures the most parallel possible outlet gap with the most cost-effective design, easy handling and minimal maintenance practically independent of the respective operating conditions (see, for example, WO 88 01318 A).

In a headbox specified in the preamble of claim 1, this object is achieved in that the upper arm and the rear or downstream second central part of the central assembly are each segmented transversely to the machine direction and that the inlet-side first central part of the central assembly and the lower Nozzle wall are formed transversely to the machine direction in each case continuously.

The central assembly is thus formed by a partially segmented C-shaped bracket, with basically only those parts not segmented are, that is so running in the transverse direction are running, limit the material-carrying spaces.

If the lower nozzle wall is displaceable on a stationary support plate in the machine direction, the stationary support plate is preferably also segmented transversely to the machine direction.

If the upper nozzle wall is pivotable, for example, about a hinge about an axis extending transversely to the machine direction, a continuous hinge bearing extending transversely to the machine direction is preferably provided on the rearward or downstream end of the upper arm of the central assembly in the machine n-direction. This hinge bearing can each have a material weakening in the region between the individual segments of the adjacent upper arm.

In a preferred practical embodiment, the pitch of segments of the upper arm of the central assembly defined by the distances from segment center to segment center is equal to the pitch of the segments of the rear and downstream second central portions of the central assembly, respectively.

It is also advantageous if the division of the supporting elements and of the supporting elements defined by the distances from element center to element center is equal to the division of the segments of the central subassembly.

According to the invention, the parallelism of the outlet gap can be ensured under all operating conditions that are in question. Deformations of the upper and lower nozzle wall under varying pressure in the nozzle and / or under changing material temperature are therefore at least substantially excluded. If, during operation, the nozzle walls are pressed apart under the fluid pressure, the resulting expanding forces are produced by means of the numerous support elements or supporting elements mentioned passed fairly evenly across the machine width. A deflection of the nozzle walls is thus avoided. In addition, there is an extremely cost-effective design, that is, in particular a reduced effort for material and manufacturing (for example, machining) and for control and regulating devices. Apart from a simpler handling during operation, there is also a reduced maintenance effort.

The component cross-sectional dimensions may be the same for different headboxes of different machine widths. This simplifies the drafting and the production. The load-bearing elements only have to be dimensioned according to the maximum pressure prevailing in the nozzle.

The use of a lower nozzle wall displaceable in the machine direction makes it possible to vary the direction of the material jet without having to swivel the entire headbox. This results in a considerably lower construction costs. Otherwise, each of the support elements would have to rest on the foundation in a tilting bearing. This applies both to a headbox for a wire strainer and a headbox for a twin wire former.

As drive for such a displaceable lower nozzle wall, for example, one or more, for example two, hydraulic cylinder and linear stroke flow divider may be provided. In this case, for example Linearhub flow divider MLH series of Jahns-Regulators GmbH, D-63069 Offenbach, can be used, as described in a corresponding company publication of Jahns-Regulators GmbH in March 1997. For larger machine width, for example, one or two additional hydraulic cylinders may be provided in the central region.

Furthermore, it can be provided according to the invention that the upper nozzle wall is pivotable about an axis extending transversely to the machine direction and is connected via a plurality of distributed over the machine width separate support members with a cross member arranged above the pivot axis and that these support elements are formed transversely to the machine direction so yielding or pliable that the upper nozzle wall remains sufficiently flat at a temperature and / or pressure change.

In DE 41 06 764 A1 a headbox is already described in which the upper nozzle wall is connected via flexible rods with a rigid beam.

The headbox may in particular be provided with a central subassembly which comprises a lower arm formed by the lower nozzle wall or the support plate associated therewith, a preferably parallel upper arm, an inlet-side first central part and a second central part lying behind it in the machine direction, the upper one Arm and the two arranged between this and the lower arm central parts preferably form support elements of a turbulence generator. In this case, it is conceivable, for example, for the cross member to be connected to the central assembly via at least one lifting element, preferably over at most three lifting elements and in particular via only one lifting element or via only two lifting elements.

In an expedient practical embodiment of the head box according to the invention, the individual support elements extend at least partially generally vertically, that is perpendicular to the upper nozzle wall.

The individual support elements are preferably at least partially formed by parallel to the machine direction discs.

The cross member may be formed for example by an upstanding sheet or by a hollow beam.

Figur 1

eine schematische, teilweise geschnittene Seitenansicht einer ersten Ausführungsform eines Stoffauflaufs für einen Langsieb-Former,

Figur 2

eine schematische Schnittdarstellung des Stoffauflaufs, geschnitten entlang der Linie II-II der Figur 1,

Figur 3

eine schematische perspektivische Darstellung der zentralen Baugruppe eines Stoffauflaufs, dessen untere Düsenwand nicht verschiebbar ist,

Figur 4

eine schematische perspektivische Darstellung der zentralen Baugruppe eines Stoffauflaufs mit in Maschinenlaufrichtung verschiebbarer unterer Düsenwand und

Figur 5

eine schematische, teilweise geschnittene Seitenansicht einer weiteren Ausführungsform eines Stoffauflaufs für einen Doppelsieb-Former.

The invention is explained in more detail below with reference to embodiments with reference to the drawing; in this show:

FIG. 1

1 is a schematic, partially sectioned side view of a first embodiment of a headbox for a fourdrinier former,

FIG. 2

3 is a schematic sectional view of the headbox, taken along the line II-II of FIG. 1,

FIG. 3

a schematic perspective view of the central assembly of a headbox, the lower nozzle wall is not displaceable,

FIG. 4

a schematic perspective view of the central assembly of a headbox with displaceable in the machine direction lower nozzle wall and

FIG. 5

a schematic, partially sectioned side view of another embodiment of a headbox for a twin-wire former.

Figures 1 and 2 show a purely schematic representation of a first embodiment of a headbox 10 for a fourdrinier former of a paper machine.

Headbox 10 includes a nozzle 12 extending across the machine width, transverse to the machine direction L, having lower and upper continuous walls 14 and 16, respectively extending across the machine width. In the present embodiment, upper nozzle wall 16 is hinged about hinge 18 extending transversely to the machine direction L A pivot axis. In addition, in the present case, the lower nozzle wall 14 on a stationary support plate 20 in the machine direction L can be displaced.

A central assembly 22 of the headbox 10 comprises a lower arm formed in this case by the support plate 20, a preferably at least substantially parallel upper arm 24, an upstream first central portion 26 and a downstream in the machine direction L or downstream second central portion 28th In this case, the upper arm 24 and the two central parts 26, 28 arranged between the latter and the lower arm 20 preferably form carrier elements of a turbulence generator. In the case of a non-displaceable, integrally formed with the support plate lower nozzle wall, instead of the support plate 20, this lower nozzle wall or a corresponding portion thereof of the central assembly 22 can be attributed.

The central assembly 22 is fed, for example via a transverse distributor tube 30 fiber suspension 32.

The central assembly 22, which is designed as a turbulence generator in the present exemplary embodiment, is provided with a plurality of stage diffusers or stepless turbulence pipes. Via the lower nozzle wall 14 and the upper nozzle wall 16 and lateral boundaries 34 such as side plates or the like, the flow is led to an outlet gap 36. The machine-wide material jet emerging from the outlet gap 36 arrives in the area of a breast roll 38 on an endless circulating screen belt 40.

The stationary support plate 20 for the lower nozzle wall 14 or a stationary nozzle wall is supported on a foundation 44 by a plurality of separate support elements 42 distributed over the machine width. The support members 42 are transversely to the machine direction L-compliant or flexible formed.

As can be seen in particular with reference to FIG. 2, the individual support elements 42 extend vertically, that is to say perpendicular to the lower nozzle wall 14 or the support plate 20. In the present case, these support elements 42 are formed by disks parallel to the machine direction L. However, they may for example also be formed by studs or the like.

In the present exemplary embodiment, the support elements 42 are connected to the foundation 44 via a pedestal 46 consisting, for example, of concrete. In principle, however, these support elements 42 can also be connected directly to the foundation 44. At the other end, the support elements 42 are each connected to the support plate 20. In the case of a non-displaceable, that is integrally formed with the support plate lower nozzle wall, the support elements would be connected to the non-displaceable lower nozzle wall.

According to FIG. 2, a diagonal strut 48 is provided between the two central support elements 42, which are viewed transversely to the machine direction L. As can be seen, missing a directly connected to the support plate 20 cross member. Accordingly, it was also possible to dispense with a heating system for compensating a thermal bending of the support plate 20 or the nozzle wall 14. At most heating devices (not shown) are conceivable for changing the height of at least one of the support elements 42, for the (but hardly expectable) case of deformation of the foundation 44 or the base 46th

The above the hinge 18 about the transverse axis A pivotable upper nozzle wall 16 is connected via a plurality of distributed over the machine width separate support members 50 with a above the pivot axis A arranged cross member 52. Also, the support members 50 are again transversely to the machine direction L compliant or flexible formed.

As can be seen from Figure 2, the individual support members 50 extend vertically, that is perpendicular to the upper nozzle wall 16. In the present embodiment, the individual support members 50 are again formed by parallel to the machine direction L slices.

As a cross member 52, for example, an upright standing sheet metal or a hollow bar may be provided (see in particular Figure 1).

One or more lifting elements 54 are articulated on the one hand on the central assembly 22 and on the other hand on the cross member 52 via hinge axes 56 and 58, respectively. By means of these lifting elements 54, the upper nozzle wall 16 can thus be pivoted about the axis A in the direction of the arrow F (see FIG. 1). The lifting elements 54 may be threaded spindles, hydraulic cylinders and / or the like, for example.

Also for the linear displacement of the lower nozzle wall 14 lifting elements 60 are again provided. In the present case, the drive of the lower nozzle wall 14 via two provided on opposite sides of the hydraulic cylinder 60 and linear stroke flow divider, such as those brought by the company Jahns-Regulators GmbH on the market. With a large machine width, one or two additional lifting elements or hydraulic cylinders 60 'can be provided in the middle region.

As can be seen in particular from Figures 3 and 4, the upper arm 24 and the rear in the machine direction L second central part 28 of the central assembly 22 are each transversely to the machine direction L segmented. In contrast, the inlet-side first central portion 26 of the central assembly 22 and the support plate 20 for the displaceable lower nozzle wall 14 are formed transversely to the machine direction L in each case continuously.

Figure 3 shows a schematic perspective view of the central assembly 22 of a headbox. If the lower nozzle wall 14 (see FIG. 1) is not displaceable, it may be formed in one piece with the support plate 20.

FIG. 4 again shows a schematic perspective illustration of the central subassembly of a headbox, provided for a lower nozzle wall 14 displaceable in the machine direction L on a stationary support plate 20 (see also FIGS. 1 and 2). In this case, the stationary support plate 20 is also segmented transversely to the machine direction L.

In both cases shown in Figures 3 and 4, this results in a formed by a partially segmented C-shaped clamp central assembly 22. From the fluid pressure acting on the nozzle walls 14 and 16, resulting tensile forces by the segments 28 'of the second Central part 28 extend, and compressive forces which pass through the first central part 26.

At the rear in the machine direction L end of the upper arm 24 of the central assembly 22 is a transverse to the machine direction L extending through hinge bearing 62 of the hinge 18 (see also Figure 1) is provided, into which provided on the upper nozzle wall 16 counter element 64 (see Figure 1) engages.

In the embodiment shown in Figure 3, the hinge bearing 62 transverse to the machine direction L has a constant cross-section. In contrast, in the case of the central assembly 22 shown in FIG. 4, the hinge bearing 62 has a material weakening 66 in the region between the individual segments 24 'of the adjacent upper arm 24. It is also conceivable, for example, for the hinge bearing 62 according to FIG. 4 to be composed of a continuous lower part and of a plurality (ie, segmented) upper parts.

The division of the segments 24 'of the upper arm 24 of the central subassembly 22, defined by the distances from the middle of the segment to the middle of the segment, is equal to the division of the segments 28' of the second central part 28 of the central one in the machine direction L in both embodiments shown in FIGS Assembly 22.

In addition, in the present case, the division of the support elements 42 and the support elements 50 defined by the distances from element center to element center is equal to the pitch of the segments 20 ', 24', 28 'of the central assembly 22.

As can be seen from Figures 3 and 4, the segments 24 'and 28' of the central assembly 22 are provided in the form of individual blocks distributed across the machine width. This also applies (in the case of FIG. 4) to the upper parts of the hinge bearing 62.

Figure 5 shows a schematic, partially sectioned side view of another embodiment of a headbox 10 for a twin-wire former.

In this case, one of the central assembly 22 upstream feed part 67, the fiber suspension through the transverse distribution pipe 30 via a plurality of lines 68, wherein a transversely to the machine direction L sectioned material density control can be provided. The machine-wide material jet emerging from the outlet gap 36 passes into an inlet gap 74 formed between two screen belts 70, 72.

While in the embodiment illustrated in Figures 1 and 2, the headbox 10 is aligned substantially horizontally, the headbox 10 is in the embodiment shown in Figure 5 with its outlet gap 36 obliquely upward in the inlet gap formed between the two sieve belts 70, 72 74th directed.

Moreover, this headbox 10 has at least substantially the same structure as in the embodiments of Figures 1 to 4.

LIST OF REFERENCE NUMBERS

10

headbox

12

jet

14

Lower nozzle wall

16

Upper nozzle wall

18

hinge

20

Stationary support plate, lower arm

22

Central module

24

Upper arm

24 '

segments

26

Inlet side first central part

28

Rear second central part

28 '

segments

30

Cross manifold

32

fiber suspension

34

Lateral boundary

36

outlet gap

38

breast roll

40

screen belt

42

support elements

44

foundation

46

Base plate, base

48

diagonal bracing

50

supporting elements

52

crossbeam

54

lifting

56

joint axes

58

joint axes

60

lifting

60 '

lifting

62

hinge bearing

64

counter-element

66

material weakening

67

feed section

68

management

70

screen belt

72

screen belt

74

inlet gap

Claims (12)

1. Headbox (10) for a paper machine, having a nozzle (12) which extends over the machine width transversely with respect to the machine running direction (L) and has a lower and an upper continuous wall (14 and 16, respectively) in each case extending over the machine width, and having a central subassembly (22) which comprises a lower arm formed by the lower nozzle wall and the carrier plate (20) assigned to the latter, an upper arm (24) preferably parallel thereto, and a first central part (26) on the inlet side and a second central part (28) located behind the latter in the machine running direction (L), the upper arm (24) and the two central parts (26, 28) arranged between the latter and the lower arm (20) preferably forming carrier elements of a turbulence generator, characterized in that the upper arm (24) and the rear second central part (28) of the central subassembly (22) are in each case segmented transversely with respect to the machine running direction (L) and in that the first central part (26) on the inlet side of the central subassembly (22) and the lower nozzle wall (14) are in each case continuous transversely with respect to the machine running direction (L).
2. Headbox (10) according to Claim 1, characterized in that the lower nozzle wall (14) can be displaced in the machine running direction (L) on a stationary carrier plate (20) and in that the stationary carrier plate (20) is preferably also segmented transversely with respect to the machine running direction (L).
3. Headbox (10) according to Claim 1 or 2, characterized in that the upper nozzle wall (16) can be pivoted via a hinge (18) about an axis (A) extending transversely with respect to the machine running direction (L), and in that, at the rear end in the machine running direction (L) of the upper arm (24) of the central subassembly (22), a continuous hinge bearing (62) extending transversely with respect to the machine running direction (L) is provided.
4. Headbox (10) according to Claim 3, characterized in that the hinge bearing (62) in each case has a material weakening (66) in the region between the individual segments (24') of the adjacent upper arm.
5. Headbox (10) according to one of the preceding claims, characterized in that the pitch of the segments (24') of the upper arm (24) of the central subassembly, defined by the spacings from segment centre to segment centre, is equal to the pitch of the segments (28') of the rear second central part (28) of the central subassembly.
6. Headbox (10) according to one of the preceding claims, characterized in that the upper nozzle wall (16) can be pivoted about an axis (A) extending transversely with respect to the machine running direction (L) and is connected by a plurality of separate carrying elements (50) distributed over the machine width to a crossbeam (52) arranged above the pivot axis (A), and in that these carrying elements (50) are designed to be compliant or flexible transversely with respect to the machine running direction (L) such that the upper nozzle wall (16) remains sufficiently flat in the event of a temperature and/or pressure change.
7. Headbox (10) according to Claim 6, characterized in that the crossmember (52) is connected to the central subassembly (22) via at least one lifting element (54), preferably at most three lifting elements (54) and, in particular via only one lifting element (54) or via only two lifting elements (54).
8. Headbox (10) according to Claim 6 or 7, characterized in that, at least to some extent, the individual carrying elements (50) generally extend vertically, that is to say perpendicular to the upper nozzle wall (16).
9. Headbox (10) according to one of Claims 6 to 8, characterized in that, at least to some extent, the individual carrying elements (50) are formed by discs parallel to the machine running direction (L).
10. Headbox (10) according to one of Claims 6 to 9, characterized in that the crossbeam (52) is formed by a metal sheet standing on edge.
11. Headbox (10) according to one of Claims 6 to 10, characterized in that the crossbeam (52) is formed by a hollow beam.
12. Headbox (10) according to one of the preceding claims, characterized in that the pitch of the supporting elements (42) supporting the carrier plate (20) and the lower nozzle wall (14) on a foundation (44), and of the carrying elements (50), defined by the spacings from element centre to element centre, is equal to the pitch of the segments (20', 24', 28') of the central subassembly (22).

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