WO2025093584A1 - Vane fastening device for a headbox of a machine for producing a fibrous web - Google Patents

Abstract

The invention relates to a vane fastening device (50) for use in a headbox for a machine for producing a fibrous web, in particular a paper web, tissue web or board web, wherein the vane fastening device (50) comprises a vane holder (52) and a vane joint (51) which extend over the transverse direction of the headbox, and wherein the vane holder (52) and the vane joint (51) are movably and detachably interconnectable. According to the invention, the vane fastening device (50) is designed such that a displacement angle of the vane joint (51) in the vane holder (52) is greater than or equal to +-7° with respect to the main flow direction in the headbox, and the vane holder (52) comprises a groove having an inverted wine-glass contour shape.

Description

Lamella fastening device for a headbox of a machine for producing a fibrous web

The invention relates to a lamella fastening device for a machine for producing a fibrous web, in particular a paper, tissue or cardboard web.

Wherein the headbox comprises a turbulence generator and/or at least one lamella and a nozzle, and the turbulence generator and/or the lamella form at least two flow channels, and the at least two flow channels each have a cross-sectional area and a length and can be flowed through by a fiber suspension.

The invention also relates to a turbulence generator and a lamella included in the headbox.

Conventionally, the fiber suspension is fed via an outlet gap of a headbox nozzle of a machine for producing a fiber web in the form of a fiber suspension jet onto a rotating wire, a so-called forming wire, or into the gap between two rotating wires. There are several options for regulating the fiber suspension jet in the headbox area. The quality of the fiber suspension jet, for example with regard to its velocity distribution, turbulence, and/or the added stock fractions, can significantly influence the quality of the produced fiber web. With the help of several adjustment mechanisms, actuating elements, actuators, or other control devices, the fiber suspension jet can be regulated by a control and regulation system. This also includes the lamellae discussed in this invention.

A lamella or partition in headboxes, which is usually arranged in the nozzles to influence the fiber suspension jet, is known, for example, from documents DE 3 704 462 A1 or EP 0 681 057 A2. Document DE 3 704 462 A1 discloses a lamella in the form of an inherently rigid partition, which has a pivot axis or lamella joint at its upstream end, to which an adjustment device engages. This known construction It should allow material flows to be fed to the individual nozzle chambers at independent velocities and pressures. Furthermore, the outlet gaps of the individual nozzle chambers should be independently adjustable.

Likewise, document DE 199 62 709 A1 shows a known headbox, wherein the lamella fastening devices or lamella holders between adjacently arranged turbulence insert tubes are firmly, i.e., permanently connected to one another. Furthermore, the individual, preferably hinge-like, lamella holder is made either directly from the turbulence insert tubes by separating the corresponding surfaces of the turbulence tubes or by using a separate holder unit. The separate holder unit is, in turn, firmly, i.e., permanently or detachably connected to the turbulence generator. The detachable connection of the separate holder unit to the turbulence generator is preferably achieved by screwing to a filler piece, which is, in turn, firmly, i.e., permanently connected to the turbulence generator.

The document DE 10 2006 000 069 A1 discloses a headbox with a turbulence generator and a lamella fastening device, wherein the preferably hinge-like lamella holder is connected to the turbulence generator.

The known lamellae 5 are usually arranged in the nozzle 3 of the headbox 2 to influence the flow of the fiber suspension flowing in the main flow direction 88. For this purpose, the lamellae 5 are often inserted between each row of the turbulence generator 4 on the outflow side, as seen in the main flow direction 88.

To facilitate assembly, for hydraulic and mechanical reasons, the slat fastening device 50 of the slats 5 is usually designed as a joint which allows movement of the slat 5 about a pivot axis in the transverse direction CD.

The possible mounting angle aO of the slat 5 or the slat fastening device 50 should be designed so that the top slat is in z-direction, when mounted in the transverse direction CD, the slats can be supported by the slat tip to relieve the load on the slats themselves. For this purpose, the mounting angle aO should be smaller than the maximum angle of movement a1.

If the maximum possible angle of movement a1 is smaller than the mounting angle aO, the slat 5 can jam in the slat fastening device 50 and the mounting of the slat 5 can be made significantly more difficult, especially in the case of machines that are wide in the transverse direction CD.

For the slat fastening device 50, preferably the slat joint 51 or the slat 5 and the slat holder 52, there are two different types of load depending on the operating situation of the headbox.

During production, the fiber suspension friction between the lamella surfaces results in tensile forces that the lamella fastening device 50 must reliably handle. If the lamella 5 is used, for example, in a multi-layer headbox, in addition to the resulting tensile forces, possible differential pressures in the nozzle chambers in the z-direction induce transverse forces on the lamella fastening device 50.

When the machine or headbox 2 is shut down, a backflow 89 occurs in the nozzle 3, which inevitably occurs when the inlet line of the headbox 2 is emptied (Fig. 1 c). Due to the mobility of the lamella 5, one or more lamellae 5 rest against the nozzle lower lip 32 and block the backflow of the fiber suspension in the lower flow channels 6. The dynamic stopping of the fiber suspension, analogous to a check valve, can lead to significant loads from additional transverse forces, which cause the lamella 5' to overbend beyond the maximum movement angle a1 of the lamella fastening device 50 (Fig. 1 c).

Depending on the design of the lamella holder 52, the lamella 5 can be pulled by the backflow in the lamella holder 52 against the main flow direction 89. In this case, a reduced angle of movement a2 leads to a maximum increase in the local load Kmax at the contact points K1 and K2 of the lamella 5 or the lamella joint 51 with the lamella holder 52 (Fig. 2b) due to the unfavorable leverage ratios. This applies in particular when the headbox 2 or the nozzle 3 in so-called GAP former applications is not arranged horizontally.

However, existing designs have the disadvantage that the technical design of the lamella fastening device 50 requires large step recesses R (Fig. 2a) between the flow channels 6 of the turbulence generator 4 and the lamellae 5 to avoid the maximum loads just mentioned and, at the same time, to ensure good installation conditions. This ensures sufficient mobility of the lamellae 5 and an increase in the maximum angle of movement a1. These step recesses R impair the nozzle hydraulics and the quality of the produced fibrous web due to separation vortices when the fiber suspension flow exits the flow channels 6 in the main flow direction 88. Deposits or air bubbles can also form in the flow dead space.

The total height HH of the existing slat fastening devices 50 is also disadvantageous. This is evident when achieving a mobility of the slat 5 through a movement angle a1, which, if exceeded, results in a large moment acting on the slat joint 51 (Fig. 2b). The larger the movement angle a1, the more the slat 5 can support itself on the nozzle lower lip 32 when parked, and the fewer forces act on the slat fastening device 50. However, a large maximum movement angle a1 can only be achieved by large step recesses R, since in the existing designs the height NH of the groove 55 directly correlates to the maximum movement angle a1.

In other words, the larger the maximum angle of movement a1 is selected for the existing designs, the more height HG must be allocated to the groove 55 in the lamella holder 52, and consequently, the overall height of the nozzle 3 in the headbox 2 is increased. This, in turn, results in even higher angles of movement a1, since the uppermost lamella 5, for a given overall length, must tilt further downwards.

With small outlet cross sections of the flow channels 6 at the turbulence generator 4 to the nozzle 3, the sum of the step recesses R of the holder can take up to% of the initial nozzle height at the outlet from the turbulence generator 4. A further disadvantage for simplifying assembly, assembly, and manufacturability is that the groove 55 in the lamella holder 52 for accommodating the lamella joint 51 is significantly larger, particularly longer in the main flow direction 88 or machine direction MD, than necessary for the angle of movement a1. As a result, the backflow 89 of the fiber suspension against the machine direction MD results in a loading situation for the lamellae 5 with a reduced angle of movement a2 (Fig. 2c) during the shut-down process in many designs. This can lead to lamella breakage or irreversible deformation due to the increased lamella load.

For technical reasons, the slats are usually made up of several parts and are therefore complex.

The object of the invention is to provide an improved slat fastening device which enables an equal or greater maximum angle of movement while simultaneously reducing the step recess when exiting the flow channel.

As a further task, the improved slat fastening device is intended to avoid a maximum load situation that occurs when the headbox is switched off by a reduced angle of movement.

At the same time, functionality in terms of operation and maintenance, as well as operational reliability, must be achieved at reduced costs.

The problem is solved by means of the features of the independent claims.

According to the invention, the slat fastening device is designed with a maximum angle of movement of the slat joint in the slat holder of greater than +/- 7°, preferably greater than +/- 10°, to the main flow direction in the headbox and that the groove is designed with an inverted wine goblet contour shape, such that a passive restoring force is generated by the inverted wine goblet contour shape of the groove and the slat joint during the headbox shutdown process. Advantageously, the contour shape of the lamella fastening device allows two essentially opposite contact lines between the lamella holder and the lamella joint to form during headbox operation due to the tensile forces exerted on the lamella by the fiber suspension flow. Approximately only tensile forces are exerted on the lamella and the holder.

In all other situations, in addition to tensile and compressive forces in the machine direction MD, further torques or bending forces occur, exerting forces on the contact lines K1 and K2 in the lamella holder. Due to the special angles in the contour shape of the lamella fastening device, force vectors always form at the contact lines on the lamella joint or the lamella in the main flow direction or machine direction MD, preferably in every operating condition.

As a result, the slat joint always moves to the position of the largest possible angle of movement a1. In this situation, the slat joint rests on the slat holder at contact line K2 due to its inverted wine-glass contour. The distance or lever F3 between the two contact lines K1 and K2 is maximized, and the bending load on the material of the slat joint and slat holder at the narrow point of the slat holder is minimized.

This measure allows for a significantly reduced height of the louvre holder while maintaining a very high load capacity. This also reduces the step recesses and the overall height of the nozzle in the headbox. This system consists of a special holder and a matching louvre.

The contour shape of the groove of the slat holder can be approximated at the transition points between the individual areas with a clearly defined edge and/or with round contours or radii, the essential dimensions of which should not significantly change the specified angles.

In an alternative embodiment, the slat fastening device is characterized in that the inverted wine goblet contour shape of the Groove comprises at least three regions in the main flow direction and that a first lamella holder region is designed with an opening cross-section with an opening angle b3h and that a second lamella holder region is designed with a narrowing cross-section with a belly angle b2H up to a minimum cross-section with a foot height HF, and that thereafter a third lamella holder region is designed with an opening cross-section with a foot angle b1H, for example shown in Fig. 3c.

The slat fastening device according to the invention is characterized in that the design of the slat joint part comprises at least three areas in the main flow direction and in that a first slat joint area LG1, preferably at an end of the slat that points into the slat holder, is designed as a substantially circular end and in that a second slat joint area LG2, which directly adjoins the first area LG1 in the main flow direction, is designed as a central part with a reduced height compared to the first area, preferably with a substantially constant height, and in that a third slat joint area LG3 adjoins this, which is designed as a widening transition area, preferably with an increasing height, up to a slat main body of the slat.

In an alternative embodiment, the slat fastening device is characterized in that, at a maximum angle of movement a1 of the slat fastening device, the third region LG1 of the slat joint rests on the third region LH3 of the slat holder in such a way that a contact surface K2* is formed.

Advantageously, the passive restoring force of the slat fastening device generated by the shaping causes the slat joint or the slat to be moved back or reset to the maximum angle of movement a1 by the forces acting on the slat during a stop process of the headbox, wherein the maximum angle of movement a1 is characterized in that the respective third area LH3 and LG3 of the slat holder 52 and the slat joint 51 is such are designed so that the extent of the two areas in terms of their length and their base angle b1 H and b1 G essentially correspond.

In an alternative embodiment, the slat fastening device is characterized in that the circular end of the slat joint has a diameter greater than or equal to 3.0 mm, preferably substantially 4 mm, and less than or equal to 6.0 mm, and in that the reduced, substantially parallel central part is designed with an undersize to the foot height of greater than or equal to 50%, preferably substantially 60%, and less than or equal to 70%, and in that the extended transition area LG3 is designed with a foot angle b1 G of greater than or equal to 15 ° and less than or equal to 35 °, preferably substantially 25 °, and in that the distance from the center point of the circular end to the beginning of the transition area is designed to be greater than or equal to 1.0 mm, in particular greater than or equal to 2.5 mm, preferably substantially 3.0 mm, and less than or equal to 5.0 mm, in particular less than or equal to 3.5 mm.

In an alternative embodiment, the slat fastening device is characterized in that the slat joint at the end pointing into the slat holder is designed as a substantially circular shape and that the circular shape has a diameter greater than or equal to 3.0 mm, preferably substantially 4 mm, and less than or equal to 6.0 mm.

In an alternative embodiment, the slat fastening device is characterized in that the slat holder is designed with a foot height HF greater than the diameter of the circular end of the slat joint, preferably with an oversize greater than or equal to 0.1 mm and less than or equal to 0.8 mm, preferably substantially 0.4 mm.

In an alternative embodiment, the slat fastening device is characterized in that the groove is designed with a base angle b1 H greater than or equal to 30° and less than or equal to 90°, preferably substantially 60°. In an alternative embodiment, the slat fastening device is characterized in that the groove is designed with a belly angle b2H greater than or equal to 30°, in particular greater than or equal to 60°, preferably greater than or equal to 90°, and less than or equal to 160°, in particular less than or equal to 120°.

In an alternative embodiment, the slat fastening device is characterized in that the groove is designed with an opening angle b3H greater than or equal to 10° and less than or equal to 50°, preferably substantially 20°.

In an alternative embodiment, the slat fastening device is characterized in that the slat joint is designed with a base angle b1 G greater than or equal to 15° and less than or equal to 35°, preferably substantially 25°.

In an alternative embodiment, the slat fastening device is characterized in that the slat holder has a height of greater than or equal to 6 mm, in particular greater than or equal to 7 mm, preferably substantially 8 mm, and less than or equal to 14 mm, in particular less than or equal to 9 mm.

In an alternative embodiment, the slat fastening device is characterized in that the slat holder has a foot height HF of greater than or equal to 1.5 mm, in particular greater than or equal to 2.5 mm, preferably substantially 2.7 mm, and less than or equal to 5.0 mm, in particular less than or equal to 3.0 mm.

In an alternative embodiment, the slat fastening device is characterized in that the groove of the slat holder is designed with a height of greater than or equal to 10%, in particular greater than or equal to 40%, preferably substantially 50%, of the diameter of the slat joint.

Advantageously, the excess of the groove height of the slat holder in relation to the diameter of the circular end of the slat joint creates a large space that allows easy assembly when inserting the slat. At the same time, the diameter prevents wedge formation of penetrated fibers or filler particles during disassembly, as is known from the linear movement of narrow parallel gaps, which then tend to jam.

In an alternative embodiment, the slat fastening device is characterized in that the slat holder is designed in one piece and that the slat holder is milled, eroded or extruded.

In an alternative embodiment, the slat fastening device is characterized in that the slat holder is designed in several parts in the transverse direction.

In an alternative embodiment, the slat fastening device is characterized in that the slat holder is designed in several parts, preferably two parts with an upper part and a lower part, in the vertical direction and that the parts of the slat holder can be connected to one another firmly, preferably welded, or detachably, preferably screwed.

Lamella for use in a headbox for a machine for producing a fibrous web, in particular a paper, tissue or cardboard web, wherein the lamella comprises a lamella joint and a lamella main body and, wherein the lamella joint and the lamella main body can be firmly or detachably connected to one another, the lamella joint has a contour shape according to the invention in order to fit into the inverted wine goblet contour shape of the groove of the lamella holder.

Lamella holder for use in a headbox for a machine for producing a fibrous web, in particular a paper, tissue or cardboard web, wherein the lamella holder can be firmly or detachably connected to a turbulence generator included in the headbox, the lamella holder being designed according to the invention with a groove in an inverted wine goblet contour shape.

Retrofit lamella holder for use in a headbox for a machine for producing a fibrous web, in particular a paper, tissue or Cardboard web, wherein the retrofit slat holder is connectable to an existing slat holder contained in the headbox and an existing retrofit groove, preferably a retrofit groove and retrofit tongue fastening device, the retrofit slat holder is characterized in that the retrofit slat holder comprises a slat fastening device according to the invention on a side oriented in the machine direction MD and that the retrofit slat holder comprises a retrofit tongue in the congruent shape of the existing retrofit groove of the existing slat holder on an opposite side oriented against the machine direction.

Headbox for a machine for producing a fibrous web, in particular a paper, tissue or cardboard web, comprising a turbulence generator, at least one lamella and at least one lamella fastening device, wherein the at least one lamella can be movably connected to the turbulence generator via the lamella fastening device and wherein the lamella comprises a lamella joint and the turbulence generator comprises a lamella holder designed congruently with the lamella joint and wherein the lamella holder can be rigidly, preferably permanently or detachably, connected to the turbulence generator, the headbox is characterized in that the headbox comprises a lamella fastening device according to the invention.

The invention expressly extends to embodiments which are not given by combinations of features from explicit references to the claims, whereby the disclosed features of the invention can be combined with one another in any way - as far as this is technically reasonable.

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

The invention is explained below with reference to the following figures:

Fig. 1 a shows a schematic side view of a headbox 2 with a slat fastening device 50 in production operation; Fig. 1b shows a schematic side view of a headbox 2 with a slat fastening device 50 in the stored state or during assembly; Fig. 1c shows a schematic side view of a headbox 2 with a slat fastening device 50 in the storage process;

Fig. 2a to 2c show an embodiment of a prior art slat fastening device 50 in three different loading scenarios;

Fig. 3a shows an embodiment of the slat holder 52;

Fig. 3b shows an embodiment of the lamella joint 51;

Fig. 3c shows the slat holder 52 from Fig. 3a with further dimensions;

Fig. 3d shows the slat holder 52 from Fig. 3c with alternative contouring;

Fig. 3e shows the slat holder 52 with slat joint in a maximum

Angle of movement a1 , for example when stationary;

Fig. 3f shows the slat holder 52 with slat joint in a reduced angle of movement a2 immediately after a standstill;

Fig. 4 shows an embodiment of a multi-part slat holder 52;

Fig. 5 shows an embodiment of a retrofit slat holder 52'.

To illustrate the individual directions, a Cartesian coordinate system has been created. The x-direction represents the longitudinal extension, also known as the machine direction (MD). The y-direction corresponds to the direction perpendicular to the machine direction and is referred to as the cross-machine direction (CD), while the z-direction corresponds to the vertical direction. The main flow direction 88 is also specified as a reference system; in the examples shown, this usually corresponds to the machine direction (MD) or is parallel to the nozzle lower lip 32.

Unless otherwise stated, the angles given refer to the main flow direction 88 or an imaginary parallel plane 90.

Fig. 1a shows a side view of the basic structure of a headbox 2 comprising a turbulence generator 4 with flow channels 6, a nozzle 3 with a preferably adjustable nozzle upper lip 31 and a nozzle lower lip 32. The nozzle 3 ends in the main flow direction 88, or machine direction MD, with a nozzle outlet gap 30. The turbulence generator 4 is only partially shown, and the upstream components of a headbox are also not shown. The turbulence generator 4 is shown here, by way of example, with four flow channels 6 and three lamella fastening devices 50 arranged between them, each with a lamella holder 52 that can be connected to the turbulence generator 4, and a lamella joint 51 that can be connected to the lamella 5.

Corresponding to the three slat fastening devices 50, three slats 5 are shown. Likewise, for three angles (mounting angle a0, movement angles a1 and a2), an imaginary reference plane 90 is shown, which is parallel to the main flow direction 88 and is set through the center of the height of the slat holder 52.

The position of the lamellae corresponds to a possible operating state of the headbox 2 with a fiber suspension flowing between the lamellae 5.

Fig. 1 b shows the headbox 2 from Fig. 1 a in a deactivated operating state, in which assembly and/or maintenance of the slats 5 is possible. Due to the force of gravity, the slat tips of the slats 5 are deposited on the nozzle lower lip 32 or the slats 5 arranged below in the z-direction. The force of gravity is largely absorbed by the nozzle lower lip 32.

For the uppermost slat 5 in the z-direction, the necessary mounting angle aO results, which must enable the slat fastening device 50, whereby ideally, as already explained at the beginning, the mounting angle aO should be smaller than the maximum movement angle a1.

In the embodiment shown in Fig. 1 c, the headbox 2 from Fig. 1 a and Fig. 1 b is shown during a shutdown process of the headbox 2. This transient process is characterized by the fact that the main flow direction 88 changes into a backflow 89 opposite to the machine direction MD. This usually leads to a maximum load situation of the lamella fastening device 50 because the backflow and the superimposed lamellae 5 create a negative pressure in the lower flow channels. This can cause the slats 5' arranged above to deflect beyond the maximum angle of movement a1. In an unfavorable situation, this can lead to structural failure of the deflected slats 5'.

Likewise, a further unfavorable maximum load constellation for the lamella 5 and the lamella joint 51 can occur if the lamella 5 is retracted in the lamella holder 52 by the backflow 89, as shown in Fig. 2c, and a maximum lever F3 is formed between the two contact lines K1 and K2 of the lamella joint 51 with the lamella holder 52.

Both maximum load situations (shown in Fig. 1c and 2c) are higher than the lever ratios F2 designed for the maximum angle of movement a1, as shown in Fig. 2b. Figs. 2a, 2b, and 2c were already discussed in more detail in the description of the prior art.

According to the invention, an embodiment of the slat fastening device 50 is provided, as shown in Figs. 3a-e. A special shape of the groove 55, the slat holder 52 shown in Figs. 3a, 3c, 3d, and 3e, and the corresponding counterpart of the slat 5, the slat joint 51 shown in Figs. 3b and 3e, is provided.

3a, 3c, 3d show the slat holder 52 in detail, wherein the groove 55 essentially corresponds to an inverted wine goblet contour. The slat holder 52 can be divided into three regions LH1, LH2, LH3 in the main flow direction 88 in the region of the groove 55. The inverted wine goblet contour of the groove 55 in the main flow direction 88 comprises at least three regions, wherein a first slat holder region LH1 is designed with an opening cross-section and with an opening angle b3H and a second slat holder region LH2 has a narrowing cross-section and with a belly angle b2H, reducing to a minimum cross-section with a foot height HF. The third slat holder region LH3 following thereafter is again designed with an opening cross-section and with a foot angle b1H. The slat holder 52 is further characterized in that the inverted wine-glass contour shape of the groove 55 allows a maximum overall height HH to be maintained, whereby the step recess R can be significantly reduced. The slat holder 52 ideally has an overall height HH of greater than or equal to 6 mm, in particular greater than or equal to 7 mm, preferably substantially 8 mm, and less than or equal to 10 mm, in particular less than or equal to 9 mm.

A further crucial feature of the inverted wine goblet contour shape of the groove 55 is that the slat holder 52 at the transition from the second to the third region LH2 to LH3, at its narrow point, has a foot height HF of greater than or equal to 1.5 mm, in particular greater than or equal to 2.5 mm, preferably substantially 2.7 mm, and less than or equal to 5.0 mm, in particular less than or equal to 3.0 mm.

It is advantageous for the movement angle a1 to be achieved that the groove 55 is designed with an inverted wine glass foot angle b1 H greater than or equal to 10 and less than or equal to 50°.

The geometric design of the groove enables an automatic restoring force, thus avoiding an unfavorable load condition with a reduced angle of movement a2 and minimizing the potentially occurring leverage ratios F2, F3 in interaction with the louvre joint 51, which can be connected to the louvre holder 52 in the groove 55. The connection is movable to a certain extent about a pivot axis, can absorb tensile forces very well, and avoids the previous maximum load situations of the louvres 5. It also successfully reduces the maximum overall height HH through the shape and thus the stepped recess R and consequently the overall height of the nozzle 3.

Fig. 3b shows in detail the design of the lamella joint 51 corresponding to the lamella holder 52, which can also be divided into at least three areas in the main flow direction 88. It comprises a first lamella joint area LG1 as a substantially circular end 46, which points into the lamella holder 52, followed by a second lamella joint area LG2. which is designed as a reduced, essentially parallel central part 47 and then continues into a third lamella joint area LG3, which is designed as an expanding transition area 48 to a lamella main body 49, not shown in full length.

The circular end 46 of the lamella joint 51 has, for example, a diameter GL greater than or equal to 3.0 mm, preferably substantially 4 mm, and less than or equal to 6.0 mm.

The reduced, substantially parallel central part 47 is designed with an undersize to the foot height HF of greater than or equal to 6.5%, preferably substantially 10%, and less than or equal to 20%.

Alternatively, the reduced, substantially parallel central part 47 can be designed with an undersize to the foot height HF of greater than or equal to 1.4 mm, in particular greater than or equal to 2.7 mm, preferably substantially 2.4 mm, and less than or equal to 4.0 mm, in particular less than or equal to 3.0 mm.

The extended transition area 48 is designed with a foot angle b1 G of greater than or equal to 15°, in particular greater than or equal to 25°, and less than or equal to 35°, in particular less than or equal to 25°.

The distance LG13 from the center of the circular end 47 to the beginning of the transition region 48 is designed for ideal results to be greater than or equal to 1.0 mm, in particular greater than or equal to 2.5 mm, preferably substantially 3.0 mm, and less than or equal to 5.0 mm, in particular less than or equal to 3.5 mm.

As an alternative embodiment, the slat holder 52 can be constructed in one piece in the z-direction. It can also be advantageous for the slat holder 52 to be constructed in one piece in the transverse direction CD. Ideally, the slat holder 52 is milled or eroded from a solid material; alternatively, the slat holder 52 can also be manufactured by extrusion.

Figure 3d shows the content of Figure 3c, but the wine-glass contour shape of the three areas LKH1, LH2, and LH3 was simplified by choosing a straight line shape instead of radii. This also allows for a reduction in forces at a maximum angle of movement.

Fig. 3e shows the slat holder 52 in an assembled or mounted state with the slat joint 51 of a corresponding slat 5. the slat 5 or the slat joint 51 is in its maximum angle of movement a1, for example when the corresponding headbox is at a standstill. The maximum angle of movement a1 can be determined between the imaginary parallel reference plane 90 to the main flow direction of the slat holder 52 and an imaginary center plane 91 through the slat joint 51. The maximum angle of movement a1 can be calculated from half the wine goblet foot angle b1 H of the slat holder 52 (see Fig. 3c) minus half the foot angle b1 G of the slat joint 51 (see Fig. 3b).

Furthermore, Fig. 3e shows the advantageous reduction in load by transferring the forces to an enlarged contact surface K1 * and K2 *, which, compared to the contact lines K1, K2 and K2max shown in Fig. 2a-c, enable a significant reduction in the load on the multi-plate joint 51 and the multi-plate holder 52. The contact surface K2 * is formed by the third region LG3 of the multi-plate joint 51 and the third region LH3 of the multi-plate holder 52, and the contact surface K1 * is formed by the preferably congruently shaped second region LH2 of the multi-plate holder 52 and the first region LG1 of the multi-plate joint 51, which is defined by a circular shape with the diameter GL.

The slat holder 52 shown in Fig. 4 is alternatively designed in several parts. A division in the z-direction into two parts, an upper part 52.1 and a lower part 52.2, is advantageous.

It may also be advantageous that the parts of the slat holder 52 can be connected to one another firmly, preferably welded, or detachably, preferably screwed.

Fig. 5 shows a simple retrofitting option for existing headboxes 2 with already existing lamella holders 56 with an existing or predetermined shape of the groove 58.

The retrofit slat holder 52' is characterized in that a slat fastening device 50 is included, as seen in the main flow direction 88, as described in Figs. 3a, 3b and 3c, and on the opposite side, opposite the main flow direction 88, a corresponding form 57, which congruent with the existing groove 58 in the existing headbox 2 or slat holder 56. For example, the connection can be designed as a positive-locking tongue and groove connection, which can create a fixed and detachable connection.

2 headbox

3 nozzles

4 Turbulence generator

5 slats

5' bent slat

6 flow channel

30 Nozzle exit gap

31 adjustable nozzle upper lip

32 Nozzle lower lip

46 circular end of the lamella joint

47 reduced middle section of the lamella joint

48 Transition area of the lamella joint

49 slat main body

50 slat fastening device

51 slat joint

52 slat holders

52.1 multi-part slat holder, upper part

52.2 multi-part slat holder, lower part

52' retrofit slat holder

55 Groove in the slat holder (inverted wine goblet shape)

56 existing, old slat holder

57 Retrofit spring

58 Retrofit groove

88 Main flow direction of the fiber suspension

89 Flow direction during shutdown

90 imaginary parallel reference plane to the main flow direction

91 imaginary center plane of the slat aO mounting angle a1 movement angle a2 reduced movement angle b1 H wine goblet base angle of the slat holder b2H wine goblet belly angle of the slat holder b3H Wine goblet Opening angle of the slat holder b1 G Wine goblet Foot angle of the slat joint

HF foot height of the slat holder

HH Total height of the slat holder

HL height of slat or slat thickness

HN Height of the groove

HO height of the opening

K1 contact line

K2 contact line

Kmax contact line with maximum load

K1 * Contact area

K2* Contact area

F2 Distance contact line at maximum angle of movement a1

F3 Maximum contact line distance

GL Diameter of lamella joint

LG1 first area of the lamella joint, length in flow direction

LG2 second area of the lamella joint, length in flow direction

LG3 third area of the lamella joint, length in flow direction

LG13 Distance between the slat joint center and the beginning of the third area of the slat

LH1 first area of the lamella holder, length in flow direction

LH2 second area of the lamella holder, length in flow direction

LH3 third area of the lamella holder, length in flow direction

R Step return

S Restoring force from angle of movement a2 to maximum angle of movement a1

MD Machine direction

CD transverse direction z vertical direction, height

Claims

Claims 1. Lamella fastening device (50) for fastening a lamella (5) to a turbulence generator (4) in a headbox (2) for a machine for producing a fibrous web, in particular a paper, tissue or cardboard web, wherein the lamella fastening device (50) comprises a lamella holder (52) and a lamella joint (51) which extend across the transverse direction (CD) of the headbox (2) and, wherein the lamella holder (52) and the lamella joint (51) are movably and detachably connectable to one another and, wherein the lamella joint (51) is connectable to the lamella (5), preferably forming a first end of the lamella (5), and, wherein the lamella holder (52) is connectable to the turbulence generator (4) and, wherein the Slat holder (52) comprises a groove (55) for receiving the slat joint (51), and wherein the groove (55) has an inner contour and the slat joint (51) has an outer contour, wherein the contours are formed substantially congruent to one another, and wherein a movement angle (a0, a1, a2) of the slat (5) about an imaginary axis of rotation in the transverse direction (CD) within the groove (55) is enabled, characterized in that the slat fastening device (50) is designed with a maximum movement angle (a1) of the slat joint (51) in the slat holder (52) of greater than +-7°, preferably greater than +-10°, relative to the main flow direction (88) in the headbox (2), and that the inner contour of the groove (55) is designed as an inverted wine goblet contour shape, such that inverted wine goblet contour shape of the groove (55) and the congruent outer contour of the slat joint (51), the slat joint (51) experiences a passive restoring force (S) in every position within the groove (55) and is automatically set to the maximum angle of movement (a1) and wherein the lamella joint (51) comprises at least three regions in the main flow direction and that a first lamella joint region (LG1) is designed as a substantially circular end (46) which points into the lamella holder (52) and that a second lamella joint region (LG2) is designed as a central part (47) with a reduced, preferably constant, height and that a third lamella joint region (LG3) is designed as a widening transition region (48) to a lamella main body (49). 2. Slat fastening device (50) according to claim 1, characterized in that the inverted wine glass contour shape of the groove (55) in the main flow direction (88) comprises at least three regions (LH1, LH2, LH3) and that a first slat holder region (LH1) is designed with an opening cross section with an opening angle (b3H) and that a second slat holder region (LH2) is designed with a narrowing cross section with a belly angle (b2H) up to a minimum cross section with a foot height (HF) and that thereafter a third slat holder region (LH3) is designed with an opening cross section with a foot angle (b1 H). 3. Slat fastening device (50) according to claim 2, characterized in that in a maximum angle of movement (a1) of the slat fastening device (50), the third region (LG3) of the slat joint (51) rests on the third region (LH3) of the slat holder (52) in such a way that a contact surface (K2*) is formed. 4. Slat fastening device (50) according to claim 1, characterized in that the circular end (46) of the slat joint (51) is designed with a diameter (GL) greater than or equal to 3.0 mm and less than or equal to 6.0 mm, preferably substantially 4 mm, and that the reduced, substantially parallel central part (47) is designed with an undersize to the foot height (HF) greater than or equal to 50%, preferably substantially 60%, and less than or equal to 70%, and that the extended transition region (48) is designed with a foot angle (b1 G) of greater than or equal to 15° and less than or equal to 35°, preferably substantially 25°, and that a distance (LG13) from the center of the circular end (46) to the beginning of the transition region (48) of greater than or equal to 2mm and less than or equal to 5mm, preferably substantially 3mm. 5. Slat fastening device (50) according to claim 2, characterized in that the groove (55) is designed with a base angle (b1 H) greater than or equal to 30° and less than or equal to 90°, preferably substantially 60°. 6. Slat fastening device (50) according to claim 1, characterized in that the slat joint (51) is designed with a base angle (b1 G) greater than or equal to 15° and less than or equal to 35°, preferably substantially 25°. 7. Slat fastening device (50) according to one of the preceding claims, characterized in that the slat holder (52) has a total height (HH) of greater than or equal to 6 mm, in particular greater than or equal to 7 mm, preferably substantially 8 mm, and less than or equal to 14 mm, in particular less than or equal to 9 mm. 8. Slat fastening device (50) according to claim 1, characterized in that the groove (55) of the slat holder (52) is designed with a foot height (HF) greater than the diameter (GL) of the circular end (46) of the slat joint (51), preferably with an oversize greater than or equal to 0.1 mm and less than or equal to 0.8 mm, preferably substantially 0.5 mm. 9. Slat fastening device (50) according to claim 1, characterized in that the groove (55) of the slat holder (52) is designed with a height (HN) of greater than or equal to 10%, in particular greater than or equal to 40%, preferably substantially 50%, of the diameter (GL) of the circular end (46) of the slat joint (51). 10. Slat fastening device (50) according to one of the preceding claims, characterized in that the slat holder (52) is designed in one piece and that the slat holder (52) is milled, eroded or extruded. 11. Slat fastening device (50) according to one of the preceding claims, characterized in that the slat holder (52) is designed in several parts, preferably in two parts with an upper part (52.1) and a lower part (52.2), in the height direction (z) and that the parts of the slat holder (52) can be connected to one another firmly, preferably welded, or detachably, preferably screwed. 12. Lamella (5) for use in a headbox (2) for a machine for producing a fibrous web, in particular a paper, tissue or board web, wherein the lamella (5) comprises a lamella joint (51) and a lamella main body (49), and wherein the lamella joint (51) and the lamella main body are connectable to one another firmly or detachably, characterized in that the lamella joint (51) comprises at least three regions in the main flow direction, and in that a first lamella joint region (LG1) is designed as a substantially circular end (46) pointing into the lamella holder (52), and in that a second lamella joint region (LG2) is designed as a central part (47) with a reduced, preferably constant, height, and in that a third lamella joint region (LG3) is designed as an expanding transition region (48) to a lamella main body (49). 13. Retrofit lamella holder (52') for use in a headbox (2) for a machine for producing a fibrous web, in particular a paper, tissue or cardboard web, wherein the retrofit lamella holder (52') is connectable to an existing lamella holder (56) contained in the headbox (2) and a contained, existing retrofit groove (58), preferably a retrofit groove (58) and retrofit tongue (57) fastening device, characterized in that the retrofit lamella holder (52') comprises, on a side oriented in the machine direction (MD), a lamella fastening device (50) according to claim 1, and that the retrofit lamella holder (52') comprises, on an opposite side oriented against the machine direction (MD), a retrofit tongue (57) in the congruent shape of the existing retrofit groove (58) of the existing slat holder (56). 14. Headbox (2) for a machine for producing a fibrous web, in particular a paper, tissue or cardboard web, comprising a turbulence generator (4), at least one lamella (5) and at least one lamella fastening device (50), wherein the at least one lamella (5) can be movably connected to the turbulence generator (4) via the lamella fastening device (50) and wherein the lamella (5) comprises a lamella joint (51) and the turbulence generator (4) comprises a lamella holder (52) designed congruently with the lamella joint (51) and wherein the lamella holder (52) can be rigidly, preferably permanently or detachably, connected to the turbulence generator (4), characterized in that the lamella fastening device (50) is designed according to claim 1.