WO2023198545A2

WO2023198545A2 - Damping device and membrane for a headbox of a machine for producing a fibrous material web

Info

Publication number: WO2023198545A2
Application number: PCT/EP2023/058925
Authority: WO
Inventors: Wolfgang Ruf; Markus Häußler; Frank Fey; Frank Schmidt; Martin Maier
Original assignee: Voith Patent Gmbh
Priority date: 2022-04-12
Filing date: 2023-04-05
Publication date: 2023-10-19
Also published as: WO2023198545A3

Abstract

The invention relates to a damping device (17), to be used in a headbox (1) of a machine for producing a fibrous material web, for damping pulsations in a fibrous material suspension flow, comprising a bottom part (17.1), a top part (17.2) and a membrane (12), wherein: the bottom part (17.1), the top part (17.2) and the membrane (12) can be connected to one another; the bottom part (17.1) comprises a flow channel (4); the top part (17.2) comprises a fillable pressure chamber (15); the pressure chamber (15) and the flow channel (4) each comprise an opening region (10) that are substantially congruent to one another and parallel; the membrane (12) is arranged sealingly between the bottom part (17.1) and the top part (17.2) such that the opening regions (10) of the pressure chamber (15) and of the flow channel (4) are sealed off from one another. According to the invention, the bottom part (17.1) and the top part (17.2) comprise a complementary connection element (40) and the connection element (40) is designed such that the bottom part (17.1) can be frictionally connected to the top part (17.2) and the connection element (40) of the bottom part (17.1) has several tensioning elements (44) which are suitable for pretensioning the membrane (12) in an interlocking manner.

Description

Damping device and membrane for a headbox of a machine for producing a fibrous web

The invention relates to a damping device for use in a headbox for a machine for producing a fibrous web, wherein the damping device can be flowed through by a fibrous suspension having a flow direction, for damping pulsations in a fibrous suspension flow, comprising a lower part, an upper part and a membrane, wherein the lower part, the upper part and the membrane can be connected to one another and, wherein the lower part comprises a flow channel and, wherein the upper part comprises a fillable pressure chamber and, wherein the pressure chamber and the flow channel each comprise an opening area which is essentially congruent and parallel to one another and , wherein the membrane is sealingly arranged between the lower part and the upper part, such that the opening areas of the pressure chamber and the flow channel are sealed against one another.

The invention also relates to a membrane suitable for the damping device, a headbox with a damping device, an assembly tool and a method for assembling the membrane in a damping device.

The membrane serves to separate the medium of the fillable pressure chamber and the fibrous suspension carried in the flow channel. To dampen pulsations in the fibrous suspension flow, the membrane is held in a curvature to float in the fibrous suspension by a regulated pressure in the pressure chamber.

Devices of this type are known. The documents DE2307849 B1, DE2744512 A1, DE3003532 A1 and US4030971 A each disclose a headbox with a pulsation damper for dampening hydraulic vibrations in the pulp suspension flowing through it. Document US4030971 A shows a device for damping hydraulic vibrations in a transverse distribution pipe and, in a further variant, in an inlet line to the headbox. In both cases, a membrane is used, which is arranged between the fibrous suspension and a pressure pad. In the first variant, the membrane cuts through the transverse distribution pipe, viewed in cross section, approximately diagonally, so that the fibrous suspension flow flows directly against the membrane at an acute angle. This can limit the damping effect and hydraulic problems can occur. The design effort here is considerable. In addition, the usable coupling surface between the membrane and the pressure cushion depends on the dimensions of the cross distribution pipe and is therefore not freely selectable.

This also applies to the second disclosed variant with an external damper in the inlet line of the headbox, in which the size of the membrane depends on the size, that is to say the diameter, of the inlet line to the headbox. In addition, the damping of the pulsations is at a large distance from the headbox nozzle. In this way, new pulsations can arise that are no longer dampened. The damping effect is also lower there.

Another disadvantage in designs that correspond to the state of the art shown is the proposed multi-stage connecting elements and corresponding designs of the membrane.

The disadvantages are particularly evident in the assembly and maintenance of the membrane. The proposed multi-stage connecting elements are composed of a first connecting element for the membrane and a further connecting element for the pressure chamber. Furthermore, the first connecting element is designed in such a way that the membrane is held in position and prestressed with two different clamping systems. The use of two clamping systems results in an area that is technically difficult to control and must be installed very carefully to ensure a good seal. The further connecting element, which connects the upper part to the lower part, also creates a final seal to the environment. A further disadvantage of a multi-stage connecting element is a high number of screw connections that have to be loosened and/or tightened in a time-consuming manner for initial assembly and maintenance.

The pre-setting of the pre-tension of the membrane for optimal damping is also disadvantageous; this is very complex to set or calibrate, since the pre-tension of the membrane is undefined and has to be adjusted by the assembly personnel using different methods and tools.

Another disadvantage is that the position of the membrane is controlled via a mechanical controller that holds the membrane in position. The position control takes place via a continuous, defined filling flow into the fillable pressure chamber. This lifts the membrane in the direction of the pulp suspension, thereby generating an air leakage stream that continuously escapes from the pressure chamber through a drain line into the environment. The mechanical mechanism creates a position control of the membrane by appropriately shaping a pressure plate on the membrane, by throttling the filling line and the drain line, and by the membrane's own weight.

Position control of the membrane based on a differential pressure measurement between the pressure chamber and the flow channel is equally disadvantageous. Accurate differential pressure measurement is difficult because a high measurement resolution is necessary and the differential pressure of a compressible medium, such as air, is measured against the fiber suspension.

The membrane itself also has an impact on the hydraulic system due to its shape and thus influences the flow itself. The differential pressure control regulates the membrane to a constant voltage, which is particularly problematic due to the change in the membrane material in the long term For example, a gradual change in the elastic modulus of the membrane material has an impact on the position and thus on the damping properties of the membrane.

The object of the invention is therefore to propose an improved damping device for a headbox with a simple and effective integrated damping of hydraulic pulsations, as well as to provide a membrane for the proposed damping device for damping hydraulic pulsations.

A further aspect of the invention is to improve the improved damping device and membrane in such a way that the assembly and maintenance work of the damping device is significantly simplified and longer service lives can be achieved.

The task is solved by features of the independent claims.

The damping device according to the invention is characterized in that the lower part, the upper part and the membrane comprise a common, complementary connecting element and that the connecting element is designed such that the lower part can be connected to the upper part in a non-positive manner and that the connecting element of the lower part has a plurality of clamping elements , preferably several circumferential clamping bolts, which are suitable for positively prestressing the membrane.

Advantageously, the connecting element is designed in such a way that a non-positive connection of the lower part and the upper part can be achieved and also with the same connecting element, at the same time a positive connection can be achieved by the clamping elements with the membrane. Advantageously, improved assembly and maintainability as well as an extended service life can be achieved by a connecting element designed according to the invention.

The membrane must be slightly pre-tensioned during operation so that temperature expansion, swelling and extrusion effects are compensated for by clamping the membrane between the lower part and upper part during operation.

For this purpose, the clamping elements are arranged all around at a distance or a division into which the membrane is suspended under tension before assembly of the upper part.

Advantageously, the pretension of the membrane is adjusted by a combination of the membrane and the position of the tensioning elements. There is no need to readjust the pretension of the membrane, since the initial adjustment of the pretension and continuous measurement of the position of the membrane allow the pressure in the fillable pressure chamber to be adjusted precisely to the pulsations that occur during operation and essentially with no time delay

In an alternative embodiment, the damping device is characterized in that the pressure chamber comprises a non-contact measuring system, preferably a laser measuring system or an ultrasonic measuring system or a radar measuring system, for continuously measuring the position of the membrane.

The position measurement is advantageously carried out without contact, which means reduced or no wear on the membrane at the measuring point and thus improves maintainability.

Further advantageously, the accuracy can be increased through a high-resolution, non-contact measuring system and integrated into the pressure chamber through a compact and simple design. Just as advantageously, the measurement signal can be used for further predictable maintenance purposes of the upstream devices, since the position can be transferred directly into pressure fluctuations and can therefore record a long-term trend of the changes.

Advantageously, by controlling the actual position of the membrane via a non-contact measuring system, the long-term behavior and an effect on the preload of the membrane will be shown and thus a reduction in the material stress on the membrane itself.

In an alternative embodiment, the damping device is characterized in that the non-contact measuring system can be connected to a regulation and/or control device in such a way that a pressure in the pressure chamber is continuously regulated.

Advantageously, the position of the membrane can be measured continuously using a non-contact and high-resolution measurement signal without influencing the measurement system itself, the continuous measurement signal being further processed directly in a regulation and control device and by high-resolution adjusting devices in a filling line and/or a drain line of the processed fillable pressure chamber continuously regulates a pressure during operation depending on the position of the membrane. The adjusting devices used can be, for example, throttles and/or adjustable valves that can be adjusted with electrical actuators.

Advantageously, a non-contact measuring system for position determination simplifies the calibration process during assembly by means of a control and regulating device that can be continuously changed during operation based on the measurement signal. This also improves the assembly and maintainability of the damping device. In an alternative embodiment, the damping device is characterized in that the connecting element is a flange connection, preferably around the opening area and the pressure chamber, preferably a square, preferably rectangular or square, flange connection, and in that the connecting element has a lower part assignable lower flange and an upper flange that can be assigned to the upper part and is complementary to the lower flange.

The connection is advantageously designed as a flange connection with screws, with holes with threads in the lower part or a through hole for fixation by bolts with a lock nut can be provided in the lower and upper parts.

By using a sufficiently high tightening torque for the screws, a frictional connection between the lower part and the upper part can be achieved.

In an alternative embodiment, the damping device is characterized in that the connecting element is designed such that when the damping device is in a closed state, the lower part and the upper part completely enclose the membrane.

In an alternative embodiment, the damping device is characterized in that the connecting element of the upper part for the several clamping elements, preferably several rotating clamping bolts, comprises at least one complementary recess for the clamping elements, preferably a complementary recess, preferably bore, for each clamping element, which is suitable is to provide a positive connection between the clamping elements and the recess when connecting the lower part to the upper part.

In an alternative embodiment, the damping device is characterized in that the connecting element in the lower part has several adjustment elements, preferably includes conical adjustment elements. For example, conical stud bolts are included on the lower part, which can be used for precise assembly of the upper part and as fasteners for the openings of the mounting tabs in the membrane.

In an alternative embodiment, the damping device is characterized in that the connecting element comprises a recess for the membrane in the upper part and/or in the lower part in the area of overlap with the membrane, and that the recess for the membrane has an offset dimension of less than a small thickness the membrane is carried out.

Advantageously, the connecting element of the lower part and/or the upper part is designed to be reduced in the area of the flow space in order to form a space for the membrane. The reduction is advantageously carried out smaller than the thickness of the membrane. The amount of reduction corresponds to the clamping force required for the membrane.

In an alternative embodiment, the damping device is characterized in that the connecting element comprises a pressure-resistant, rotating, in particular multi-part, spacer plate and is arranged in such a way that the lower part and the upper part produce a frictional connection.

Advantageously, the spacer plate is designed with a thickness less than or equal to the thickness of the membrane, preferably with an undersize of more than 1 mm compared to the thickness of the membrane, so that the smaller thickness of the spacer plate creates a predefined clamping of the membrane.

Furthermore, the spacer plate can ensure a strong frictional connection between the lower part and the upper part and thus ensure a clearly defined tightening torque for the flange screws.

Furthermore, the spacer plate prevents the membrane clamping from being exceeded, which can lead to the membrane being destroyed. In an alternative embodiment, the damping device is characterized in that the connecting element simultaneously comprises a clamping system for flat and non-positive clamping of the membrane.

When the damping device is closed, the selective, form-fitting connection of the membrane to the clamping elements is achieved by a circumferential clamping system through a flat, force-fitting connection or a force-induced form-fitting connection of the membrane to the lower part and upper part of the damping device. This relieves the pressure on the point connections for continuous operation and represents a longer-lasting solution for operation.

Likewise, in addition to fixing the membrane, the connecting element also achieves a seal from the environment through only one common, preferably a single, connecting element.

Advantageously, the shape of the connecting element and/or the spacer plate exerts a clearly defined clamping force on the membrane, which, however, must not be too large, otherwise the membrane will be elongated by extrusion effects and lose its required pre-tension or, in extreme cases, by too much high clamping force is damaged.

The connecting element ensures simple and error-free assembly by operating or maintenance personnel without the need for additional calibration and measuring devices.

In an alternative embodiment, the damping device is characterized in that the clamping system is designed with a clamping width of less than or equal to 35mm, preferably less than or equal to 25mm.

The clamping system is advantageously integrated into the lower part and/or lower part, so that the membrane resting on the lower part is positively clamped by the upper part with a predefined clamping force. In an alternative embodiment, the damping device is characterized in that the clamping system has a surface structure integrated on the upper part and/or a surface structure integrated on the lower part and/or a separate circumferential clamping plate with an integrated surface structure and/or an area provided on the surface of the membrane increased surface roughness, a positive connection is formed, such that the clamping system clamps the membrane by a positive and non-positive connection.

Advantageously, in the clamping system provided with the corresponding clamping width, a positive connection is achieved through the surface structure by appropriate shaping in addition to the non-positive connection of the components to one another. For this purpose, the respective surfaces are adjusted in the upper part, lower part and/or on the membrane in the area of the clamping system. For example, the surface roughness of the associated area of the membrane is increased and/or the surface of the lower part and/or upper part is designed with a surface structure, for example with beads, elevations or grooves. Furthermore, alternatively or in combination with the two options mentioned, a separate, preferably circumferential, clamping plate with a corresponding surface structure can also be provided. A separate clamping plate can also advantageously use a membrane with a smaller thickness in a damping device designed for a larger thickness.

To reduce the screw forces for the non-positive connection of the lower part to the upper part, the distance SA of the bolts and / or screw connection to the pressure chamber or the flow channel is kept as small as possible. It is also advantageous if the clamping width can be kept small.

In an alternative embodiment, the damping device is characterized in that the pressure chamber has a convex, in particular a semicircular, cross section. This reduces the amount of material required for a pressure-stable pressure chamber. In an alternative embodiment, the damping device is characterized in that the pressure chamber can be filled with a compressible medium, in particular with air or a liquid with gas inclusions or a solid with gas inclusions, and in operative connection with a regulation and / or control device for setting a pressure can be brought into the pressure chamber, preferably depending on the static pressure in the flow channel. A compressible medium can be, for example, air, or in the case of a liquid with gas inclusions, for example a foam, or in the case of a solid with gas inclusions, for example a foam.

In an alternative embodiment, the damping device is characterized in that the opening area is formed by several openings. The damping behavior can be advantageously influenced by dimensioning the size of the openings.

In an alternative embodiment, the damping device is characterized in that each opening is assigned an individual membrane.

In an alternative embodiment, the damping device is characterized in that a single membrane is assigned to the opening area. This also applies in the event that the opening area includes several sub-areas.

In an advantageous further development, the upper part of the damping device is designed to be foldable, at least in the area of the connected membrane. For this purpose, hinges can be provided which connect the first and/or the second flow wall to the headbox. This allows for easy maintenance or replacement of the membrane.

A membrane according to the invention for use in a damping device according to the invention is characterized in that the membrane has a Connecting element of the damping device has a substantially complementary, flat shape and completely seals the opening area, and, distributed over its circumference, the membrane comprises a plurality of clamping openings, arranged in such a way that the clamping openings are arranged in a complementary manner to the clamping elements of the damping device.

In an alternative embodiment, the membrane is characterized in that the membrane comprises a plurality of pull or assembly openings over half, preferably over a quarter, of its circumference, preferably on at least one, two or three sides, in addition to the clamping openings.

Advantageously, additional pull or assembly openings are provided over a certain distance of the circumference or on at least one side of the flat membrane in addition to the clamping openings, such that the pull or assembly openings are only used when installing the membrane in the damping device and when closed are in a non-functional state.

In an alternative embodiment, the membrane is characterized in that the clamping openings are designed with a substantially round shape and that the clamping openings are designed with a diameter of less than or equal to 15 mm, preferably less than or equal to 10 mm.

Advantageously, the clamping openings can be made round by directly adjusting the pretension, with elongated holes or oval opening shapes being provided if the pretension of the membrane can be adjusted.

In an alternative embodiment, the membrane is characterized in that the clamping openings are designed at a distance from the peripheral edge of the membrane of less than or equal to 30mm, preferably less than or equal to 20mm.

In an alternative embodiment, the membrane is characterized in that the centers of the clamping openings are at a distance from one another in one Distance of less than or equal to 100mm, preferably less than or equal to 80mm, are carried out.

Advantageously, the distance T1 or the pitch T1 is designed with a smaller distance for a round design of the clamping openings for better force distribution in the membrane.

In an alternative embodiment, the membrane is characterized in that the pull or mounting openings are designed with a diameter of less than or equal to 10mm, preferably less than or equal to 8mm.

In an alternative embodiment, the membrane is characterized in that the pull or assembly openings are arranged centrally between the clamping openings.

In an alternative embodiment, the membrane is characterized in that the pulling or mounting openings are arranged in line with the clamping openings or that the pulling or mounting openings are arranged offset from the clamping openings in the direction of the edge of the membrane.

In an alternative embodiment, the membrane is characterized in that the material of the membrane is an elastomer, the elastomer being selected from the following group: perfluororubber-FFPM, fluororubber-FPM, tetrafluoroethylene, fluoropropylene rubbers-FEPM, chlorobutadiene rubber-CR, Polyurethane PU, acrylonitrile butadiene rubber NBR, ethylene propylene polymers EPDM, tetrafluoroethylene Teflon, polyphenylene sulfone PPSU, polycarbonate PC, polyethylene PE and that the material is reinforced by fibers and/or reinforcing threads.

Thermoplastics such as tetrafluoroethylene-Teflon, polyphenylene sulfone-PPSU, polycarbonate-PC and polyethylene-PE can also be suitable. Particularly preferred materials for the membrane are ethylene propylene polymer EPDM and fluororubber FPM.

The hardness of the membrane material can be greater than 40 ShoreA to reduce the tendency to flutter.

For lower demands on pulsation damping, it is also conceivable that the material of the membrane comprises metal, in particular stainless steel, and is preferably designed as a composite material. Composite material can be a coated metal sheet.

In an alternative embodiment, the membrane is characterized in that the membrane is designed with a thickness of greater than or equal to 1 mm, preferably greater than or equal to 2 mm, and less than or equal to 8 mm, preferably less than or equal to 8 mm.

In an alternative embodiment, the membrane is characterized in that the membrane comprises at least one area with a reflection-increasing coating or plating on the side facing the opening area of the upper part, preferably on at least one opening assigned to the non-contact measuring system.

In an alternative embodiment, the membrane is characterized in that the membrane is free of mounting tabs on its circumference.

In an alternative embodiment, the membrane is characterized in that the membrane comprises mounting tabs on its circumference.

Advantageously, at least four, preferably six or eight, protruding mounting tabs distributed over the circumference are included on the membrane. Each mounting bracket includes at least one adjustment or positioning opening for a rough initial alignment during assembly and/or maintenance. Mounting tabs are advantageously provided on the membrane in such a way that sole installation by one person from the operating and/or maintenance staff is possible. In a first assembly step, the mounting tabs are hooked with their adjustment or positioning openings onto the intended adjustment elements, preferably positioning pins, of the lower part of the damping device, so that the membrane is roughly aligned and held above the flow channel so that the membrane does not fall into the flow channel .

In a second step, the clamping openings are connected to the clamping elements of the lower part on a side opposite to the side with the pull or assembly openings; the corresponding step is repeated once or twice on the remaining sides without pull or assembly openings. In a further step, an assembly tool with an assembly tool holding element is connected to the lower part and then the pull or assembly openings of the membrane are connected to a pull opening gripper element. The person then tensions the assembly tool so that the remaining clamping openings are connected to the corresponding clamping elements.

This gives the membrane a predefined, fixed, unchangeable preload. The final assembly of the upper part of the damping device takes place without further interaction with the membrane.

In an alternative embodiment, the membrane is characterized in that the membrane comprises a circumferential area on the surface facing the upper part with increased surface roughness for the clamping system and that the area lies within the area spanned by the clamping openings and that the area has a circumferential width in the direction of the center of the spanned surface of less than or equal to 35mm, preferably less than or equal to 25mm. In an alternative embodiment, the membrane is characterized in that the membrane is essentially a square surface with a width of less than or equal to 1 m, preferably less than or equal to 0.8 m, and a length of less than or equal to 2 m, preferably less than or equal to 1.5 m , is executed.

A headbox for a machine for producing a fibrous web, through which a fibrous suspension having a flow direction can flow, comprising at least one fibrous suspension inlet for supplying the headbox with a fibrous suspension and a damping device, is characterized in that a damping device according to the invention is included and that the Damping device in which at least one fibrous suspension inlet is provided before dividing the fibrous suspension in the transverse direction.

The invention avoids the disadvantages of the known headboxes, particularly with regard to the damping of hydraulic pulsations.

Headbox for a machine for producing a fibrous web through which a fibrous suspension having a flow direction can flow, comprising at least one machine-wide flow channel which is upstream of a turbulence generator and a nozzle following the turbulence generator and a damping device, is characterized in that a damping device according to the invention is included and that the damping device is provided in the machine-wide flow channel, immediately in front of the turbulence generator, and that the damping device extends essentially over the entire width of the machine-wide flow channel.

The solution is structurally very simple and also very effective, as the damping of the hydraulic pulsations occurs directly in front of the turbulence generator. In addition, this solution can be adapted to different damping requirements for the flow pulsations. One flow wall or both flow walls can be equipped with the damping device. An assembly tool for assembly of a membrane according to the invention in a damping device according to the invention is characterized in that the assembly tool comprises several, preferably six, pull opening gripper elements which can be connected to the pull openings of the membrane and that the assembly tool comprises at least one assembly tool attachment element, which is connected to a assembly tool attachment element complementary assembly tool holding element can be connected to the lower part of the damping device.

A method according to the invention for mounting a membrane according to the invention in a damping device according to the invention is characterized in that a. the clamping openings of the membrane are connected to the clamping elements of the lower part on the opposite sides with the pull or assembly openings; b. an assembly tool is connected to the pull or assembly openings of the membrane; c. the assembly tool with an included assembly tool attachment element is connected to a first assembly tool holding element of the damping device; d. the assembly tool is tensioned in such a way that the clamping openings on the side with the tension or assembly openings are connected to the corresponding clamping elements of the damping device.

The invention also expressly extends to those embodiments which are not given by combinations of features from explicit references to the claims, which means that the disclosed features of the invention can be combined with one another in any way - as long as this makes technical sense. Further features and advantages of the invention result from the following description of preferred exemplary embodiments with reference to the drawings.

Show it

Figure 1 is a side view in the flow direction MD of a damping device 17 arranged in the fibrous suspension inlet 8 of a headbox 1 in a simplified representation;

Figure 2 is a top view in the z direction of a damping device 17 arranged in the fibrous suspension inlet 8 of a headbox 1 in a simplified representation with a view of a closed upper part 17.2;

Figure 3 is a top view in the z direction of a damping device 17 arranged in the fibrous suspension inlet 8 of a headbox 1 in a simplified representation with a view of the lower part 17.1 and an inserted membrane 12 with an open upper part 17.2;

Figure 4a shows an embodiment of a headbox according to the invention with a damping device in a simplified representation;

Figure 4b shows an embodiment of a headbox according to the invention according to Figure 4a with a swung-away damping device in a simplified representation;

Figure 5a shows a first variant of an opening area 10 of the pressure chamber 15 with membrane 12 in a simplified representation;

Figure 5b shows a second variant of an opening area 10 of the pressure chamber 15 with membrane 12 in a simplified representation;

Figure 6a shows a top view of an assembly tool 63 for assembly of a membrane 12 on the connecting element of the lower part 41;

Figure 6b shows an assembly tool 63 in a side view in the flow direction MD for assembly of a membrane 12 in the damping device 17; Figure 7 shows a further variant of a damping device and a flow channel of a headbox according to the invention in a simplified representation.

Corresponding elements of the exemplary embodiments in the figures are provided with the same reference numbers. The functions of such elements in the individual figures correspond to one another unless otherwise described and this does not lead to contradictions. A repeated description is therefore omitted. It is also pointed out that the different features of the exemplary embodiments shown can be exchanged and combined with one another. The invention is therefore not limited to the combinations of features shown in the exemplary embodiments shown.

To clarify the individual directions, a Cartesian coordinate system has been created, which can be used to illustrate the individual directions. The x-direction illustrates the extension in the longitudinal direction, which is also referred to as the machine direction MD (“Machine Direction”). The y-direction corresponds to the direction perpendicular to the machine direction and is called the cross-machine direction or CD (“cross-direction”), while the z-direction corresponds to the height direction.

Figure 1 shows a side view in the flow direction MD of a damping device 17, which is arranged in the fibrous suspension inlet 8 of a headbox 1 in a simplified representation.

The fiber suspension flows through the inlet 8, which is only shown in part, in the flow direction 18 shown by an arrow.

The damping device 17 comprises several elements, among other things, the damping device 17 has a lower part 17.1 and a, preferably removable, upper part 17.2. The damping device 17 further comprises a replaceable or replaceable membrane 12, which is subject to wear during operation of the damping device 17 and should be replaced regularly.

The lower part 17.1 of the damping device 17 comprises a flow channel 4, which transports the fibrous suspension 18 in a preferably circular or convex or semicircular cross section. For reasons of strength, the lower part 17.1 is stiffened in the machine direction MD with at least one reinforcing rib 30, preferably several reinforcing ribs 30, in the transverse direction CD. The lower part 17.1 can, as shown, be supported on a machine level 50 or a floor 50 to introduce force. Likewise, the lower part 17.1 can optionally also establish the connection to the subsurface 50 via stand elements 51.

As a further alternative embodiment, the lower part can also be arranged in a free-floating manner on another component, such as the fiber suspension inlet 8.

The removable upper part 17.2 of the damping device 17 comprises a fillable pressure chamber 15, which can be filled with a compressible medium in a closed state with the lower part 17.1. For example, air or a liquid with gas inclusions or a solid with gas inclusions can be used as the compressible medium.

For reasons of strength, the upper part 17.2 is, analogously to the lower part 17.1, stiffened across the machine direction MD with at least one reinforcing rib 31, preferably several reinforcing ribs 31, in the transverse direction CD. Furthermore, several transport openings 32 can be provided on the reinforcing ribs 31, which are suitable, for example, as a receptacle for a crane to remove the upper part 17.2 from the lower part 17.1 for the assembly and maintenance of a membrane 12 located in between.

In a “closed state” of the damping device 17, the lower part 17.1, the upper part 17.2 and the membrane 12 in between are connected to one another. In an “open or open state” of the damping device 17, the upper part 17.2 is removed from the lower part 17.1.

The pressure chamber 15 of the upper part 17.2 and the flow channel 4 of the lower part 17.1 each comprise an opening region 10 that is essentially congruent and parallel to one another. The pressure chamber 15 is designed in a preferably circular or convex or semicircular cross section.

The membrane 12 is sealingly arranged between the lower part 17.1 and the upper part 17.2, such that the two opening areas 10 of the pressure chamber 15 and the flow channel 4 are sealed against one another in a closed state.

The lower part 17.1 and the upper part 17.2 further comprise a mutually complementary connecting element 40, which can be designed, for example, as a circumferential flange 40.

The term “all-round” means that the flange has a closed circular or multi-sided circumference when viewed from above in order to ensure an even connection between the lower and upper parts. Advantageously, the flange is designed as a square or four-sided shape, for example a rectangular (as shown) or square shape.

Furthermore, in a closed state, the connecting element 40, the membrane 12 and the two opening areas 10 are arranged in an area 9 that is essentially parallel to one another.

The connecting element 40 includes a corresponding lower flange 41 which can be assigned to the lower part 17.1, as well as a complementary counterpart to the lower flange 41, the upper flange 42. As shown, the lower flange 41 can be connected to the upper flange 42 with several bolt connections 43 (shown on the left in the picture) and/or screw connections 43 (shown on the right in the picture). If it is a bolt connection 43, the upper flange 42 and lower flange 41 include bores 43 'at the corresponding locations (see Figure 3). If the connection is designed as a screw connection 43, a threaded hole 43 '(see Figure 3) is advantageously provided in the lower flange 41.

To reduce the screw forces 43 for a non-positive connection of the lower part 17.1 to the upper part 17.2, the distance SA to the pressure chamber 15 or the flow channel 4 is kept as small as possible.

In the embodiment shown, the pressure chamber 15 has several, optional, individual openings 11 in the opening area 10, which can serve as a support for the membrane 12. The openings 11 can be designed, for example, circular or elongated. 1 further shows an alternative embodiment of the upper part 17.2 of the damping device 17 with three openings 11 in the opening area 10.

The embodiment shown further includes a non-contact measuring system 24 arranged within the pressure chamber 15.

The non-contact measuring system 24 can be designed as an inductive or capacitive or optical or acoustic electromagnetic measuring system 24. An inductive measuring system can also be used reliably in a contaminated print medium.

For example, the non-contact measuring system 24 can advantageously be designed as a laser measuring system 24 or an ultrasonic measuring system 24 or a radar measuring system 24 for continuously measuring the position of the membrane 12.

The non-contact, digital measuring system 24 enables a high-resolution sampling rate in the range of greater than 120 Hz, preferably greater than 1000 Hz, and accuracy values in the range of less than 0.1 mm, preferably less than 0.05 mm, in particular less than or equal to 0.01 mm. Compared to standard control via differential pressure, complex commissioning procedures can be reduced or eliminated completely. Likewise, a very precise initial adjustment of the membrane 12 and calibrations for converting pressure into length can be reduced or eliminated completely

The measuring system 24 is arranged and aligned within the pressure chamber 15 in such a way that the continuous measurement is carried out with a measuring beam 25, which is directed through the opening region 10 and/or an opening 11 onto the membrane 12 and is reflected there. The measuring system 24 can itself be connected to a higher-level control and regulation device via cabling that can be reached outside the pressure chamber 15 or a radio signal, such that a pressure in the pressure chamber 15 is continuously regulated.

Due to the high sensitivity of the non-contact measuring system 24, the measuring system 24 can also be used for diagnostic purposes; for example, the membrane 12 experiences constant wear during operation due to the constant up and down movement for damping the pulsations in the fibrous suspension flow in the flow channel 4. Through Due to this wear, the material of the membrane 12 in the opening area 10 and/or the openings 11 tends to elongate over time. This elongation can be measured by the non-contact measuring system 24 and compensated for reliably and without further maintenance measures during operation by readjusting the pressure in the pressure chamber 15. This advantageously enables an extension of the operating phase and advance planning of a necessary replacement of the membrane 12.

The non-contact measuring system 24 detects the position of the membrane 12 through one or more opening areas 10 and/or openings 11, i.e. in the unsupported area of the membrane 12, via a measuring beam 25, shown here in dashed lines. Advantageously, the measuring system 24 can be firmly connected to the pressure chamber 15 and thus be statically sealed and thus possible leaks from the pressure chamber 15 through the measuring system 24 into the environment can be prevented.

The non-contact measuring system 24 supplies the measuring signals for the control system, which regulates the pressure of the compressible medium in the pressure chamber 15 and thus enables the preload and position of the membrane 12 to be adjusted in order to optimally adapt to the boundary conditions in the flow channel 4 in the fibrous suspension flow Damping properties to be adjusted.

The membrane 12 comprises, on the surface facing the pressure chamber 15, preferably in the opening area 10 or at least one opening 11, a reflection-increased area compared to the material of the membrane 12. The reflection-increased area is preferably as a reflection-increasing coating or a plating on the surface Pressure chamber 15 directed surface of the membrane 12 executed.

The connecting element 40 is designed in such a way that when the lower part 17.1 and the upper part 17.2 are closed, the membrane 12 is completely enclosed by the connecting element 40.

The connecting element 40 of the lower part 17.1 or the lower flange 41 comprises a plurality of tensioning elements 44, which are suitable for prestressing the membrane 12 in a geometrically predefined position. The clamping elements 44 are designed, for example, as clamping bolts 44 running around, which are arranged in the lower flange 41. Depending on the size and design of the damping device 17, more or fewer clamping elements 44 are provided over the circumference of the connecting element 40.

The membrane 12 must be slightly prestressed during operation so that temperature expansion, swelling and extrusion effects are prevented by clamping in the clamping area 45 over a clamping width KB of the membrane 12 between the lower part 17.1 and upper part 17.2 are compensated during operation. For this purpose, the clamping elements 44 are arranged circumferentially at a distance T1 or a division T1, into which the membrane is suspended under tension before assembly of the upper part.

Advantageously, the pretension of the membrane 12 is adjusted by a combination of the precisely manufactured membrane 12 and the exact position of the tensioning elements 44. There is no need to readjust the pretension of the membrane 12, since advantageously, through the initial adjustment of the pretension and a continuous measurement 24 of the position of the membrane 12, the pressure in the fillable pressure chamber 15 corresponds exactly and substantially to the pulsations in the flow channel 4 that occur during operation cannot be adjusted to any time offset.

The connecting element 40 of the upper part 17.2 further comprises complementary recesses 47 for the several clamping elements 44 in the lower part 17.1, for a preferably positive enclosure of the clamping elements 44 in the closed state. For example, the complementary recess 47 of the clamping elements 44 is designed as a bore, which is intended to provide a receptacle when connecting the lower part 17.1 to the upper part 17.2.

The connecting element 40 of the upper part 17.2 further comprises, in the area of the pressure chamber 15 or the flow channel 4 or the opening area 10, a recess 49 in the upper part 17.2 for a clamping system 45, so that the area of the recess 49 is suitable for receiving the membrane 12 and in the remaining area of the connecting element 40 of the upper part 17.2, upper flange 42, to produce a non-positive connection with the connecting element 40 of the lower part 17.1, lower flange 41.

The connecting element 40 of the lower part 17.1 and/or the upper part 17.2 is advantageously in the area of the flow space 4, 15 with a recess 49 or an offset 49 to form a space for the membrane 12. The reduction is advantageously carried out slightly smaller than the thickness of the membrane 12. The height of the reduction 49 corresponds to the required clamping force in the clamping system 45 for the membrane 12. The clamping force is further reduced as the recess increases. If the recess 49 is smaller in comparison to the parallel area 9, the clamping force is increased.

The connecting element 40 advantageously comprises a pressure-resistant, running, in particular multi-part, spacer plate 46, which is arranged such that the lower part 17.1 and the upper part 17.2 clamp the membrane 12 in a predefined manner.

Advantageously, the spacer plate 46 is designed with a thickness less than or equal to the thickness of the membrane 12, preferably with an undersize of more than 1 mm compared to the thickness of the membrane 12, so that the smaller thickness of the spacer plate 46 creates a predefined clamping 45 of the membrane 12 .

Furthermore, the spacer plate 46 can ensure a strong frictional connection between the lower part 17.1 and the upper part 17.2 and thus ensure a clearly defined tightening torque for the flange screws 43.

Furthermore, the spacer plate 46 prevents the clamping force in the clamping system 45 of the membrane 12 from being exceeded, which can lead to the membrane 12 being destroyed.

The connecting element 40 further comprises a clamping system 45 with a clamping width KB, the clamping system 45 being arranged such that the membrane 12 resting on the lower part 17.1 is clamped in the clamping system 45 by the upper part 17.2 with a predefined clamping force. The clamping system 45 is advantageously arranged behind the clamping elements 44 when viewed from the outside in the direction of the flow space 4, 15. The clamping system 45 is formed by an attachment with increased surface roughness 45 integrated on the upper part 17.2 and/or lower part 17.1 and/or an area with increased surface roughness 45 provided on the surface of the membrane 12 and/or a separate circumferential clamping plate 45. It is also advantageous if the clamping width KB can be kept small.

Furthermore, the parallel area 9 and the flow wall 7, 8 of a headbox 1 according to the invention are shown. The membrane 12 is arranged and clamped between the damping device 17 and the flow channel 4. The membrane 12 is supported in the opening area 10 of the damping device 17 by fixed areas between the openings 11 and is in operative connection via the openings 11 with the pressure chamber 15 and the compressible medium contained in the pressure chamber 15 and as well as the fibrous suspension flow in the flow channel 4, the flow direction 18 the fiber suspension flow is simplified, shown in dotted lines.

The lower part 17.1 or the lower flange 41 comprises at least one holding element 62 for an assembly tool 63 for assembly of the membrane 12.

Figure 2 shows a top view in the z direction of a damping device 17 arranged in the fibrous suspension inlet 8 of a headbox 1 in a simplified representation with a view of a closed upper part 17.2.

Figure 2 also shows several, here five, holding elements 62 for an assembly tool 63, which are included on the lower part 17.1 or on the lower flange 41.

The connecting element 40 of the upper part 17.2 and the lower part 17.1 is connected to one another with several rotating screw connections 43.

The upper part 17.2 is shown with two reinforcing ribs 31 in the transverse direction CD.

2 also shows an alternative embodiment with three, preferably two or four, non-contact measuring systems 24; one is also conceivable here Version with one or three non-contact measuring systems 24 to be available. With a multiple version, there is redundancy and the non-contact measuring systems 24 are integrated together into the regulation and control device for improved regulation.

It is advantageous if the measuring systems 24 with their measuring beams 25 are aligned with different areas of the opening area 10 of the pressure chamber 15 or different openings 11 and are thus aimed at different deflections or positions of the membrane 12 in the unsupported area. It is also advantageous if, in these areas with measuring beams 25, a reflection-increasing coating 27 or a reflection-increasing plating 27 is provided on the surface of the membrane 12 facing the measuring system 24 (see FIG. 3) in order to align the measuring beam 25 as precisely as possible to the measuring system 24 to throw back.

Figure 3 shows a top view in the z direction of a damping device 17 arranged in the fibrous suspension inlet 8 of a headbox 1 in a simplified representation with a view of the lower part 17.1 and an inserted membrane 12 with an open upper part 17.2.

Figure 3 further shows the several, here five, holding elements 62 for an assembly tool 63 shown in Figure 2, which are enclosed on the lower part 17.1 or on the lower flange 41. And in accordance with the pull and assembly openings 60 provided in the membrane 12, they are arranged on the lower flange 41. Likewise, the reflection-increasing coatings 27 are shown at the corresponding locations, but at least at one location 27, on the surface of the membrane 12.

The spacer plate 46 for a predefined non-positive connection of the upper part 17.2 with the lower part 17.1 is shown in Figure 3 as a circumferential, rectangular frame profile. However, a multi-part form of the spacer plate 46 is also conceivable; for example, the spacer plate can be divided into four parts for improved handling. For better, precise adjustment of the individual elements during assembly or assembly to a closed state, mobile or fixed adjustment elements 68, for example positioning pins 68, which are embedded in the lower flange 41 and upper flange 42, can be provided. The adjustment elements 68 improve the positioning of the components relative to one another during assembly.

The membrane 12 is in the alternative variant shown in Figure 3 optionally designed with mounting tabs 61, these mounting tabs 61 are suitable for being hooked into provided adjustment elements 68 in the lower flange 41 for a first positioning of the membrane 12 during assembly before the actual assembly of the Membrane 12 and a precise positioning of the clamping openings 48 of the membrane 12 in with assigned clamping elements 44 of the lower flange 41 takes place and thus the membrane 12 with its circumferential clamping openings 48 is suspended in the circumferential clamping elements 44.

3 with a total of ten mounting tabs 61 all around, but only two, four, six or eight mounting tabs 61 are also conceivable.

The circumferential clamping system 45 has a circumferential clamping width KB and is designed to be congruent on the upper part 17.2, the membrane 12 and/or on the lower part 17.1 with a shaping surface structure, for example with beads, in order to achieve a sufficiently high clamping force through an additional positive connection.

The clamping system 45 is advantageously arranged within the area clamped by the clamping openings 48 and the circumferential clamping width KB in the direction of the center of the clamped area is less than or equal to 35mm, preferably less than or equal to 25mm.

The membrane 12 is essentially designed as a square surface with a width of less than or equal to 1 m, preferably less than or equal to 0.8 m, and a length of less than or equal to 2 m, preferably less than or equal to 1.5 m. The membrane 12 is designed with a thickness of greater than or equal to 1 mm, preferably greater than or equal to 2 mm, and less than or equal to 8 mm, preferably less than or equal to 8 mm. In combination with the materials, the weight of the membrane 12 is very high and cannot be installed by one person.

In the lower flange 41, the enclosed holes or threaded holes 43 'for receiving the bolts or screw connections 43 are also shown.

Advantageously, additional pull or assembly openings 60 are provided on at least a quarter, preferably a half, of the circumference of the flat membrane in addition to the clamping openings 48, such that the pull or assembly openings 60 are only used when installing the membrane 12 in the damping device 17. In the square embodiment shown, the membrane 12 comprises two sides with several pull or mounting openings 60.

In the embodiment shown, the clamping openings 48 are designed in a substantially round shape and have a diameter D1 of less than or equal to 15 mm, preferably less than or equal to 10 mm.

Advantageously, the clamping openings 48 can be designed in a round shape by directly adjusting the pretension, with unfavorable elongated holes or oval opening shapes being provided if the pretension of the membrane 12 can be adjusted.

In the embodiment shown, the clamping openings 48 are designed at a distance L1 from the peripheral edge of the membrane 12 of less than or equal to 30mm, preferably less than or equal to 20mm.

In the embodiment shown, the clamping openings 48 are designed at a distance T1 or a pitch T1 from one another at a distance T1 of less than or equal to 100mm, preferably less than or equal to 80mm. The distances to each other are measured from one center point of an opening to the next center point or another corresponding reference value.

In the embodiment shown, the pull or mounting openings 60 are designed with a diameter D2 of less than or equal to 10mm, preferably less than or equal to 8mm.

In the embodiment shown, the pulling or mounting openings 60 are arranged on the corresponding sides of the membrane 12, centrally between the clamping openings 48.

The pulling or mounting openings 60 can be arranged in line with the center points of the clamping openings 48 in an embodiment not shown. The pull or mounting openings 60 are arranged in the illustrated embodiment in such a way that the center points of the pull or mounting openings 60 are arranged offset in the direction of the edge of the membrane 12 from the center points of the clamping openings 48.

4a shows an embodiment of a headbox 1 with a damping device 17 in a simplified representation, the damping device 17 being in the operating position and being connected to the headbox 1. In this example, the headbox 1 is designed with a damping device 17, which is provided in a preferably machine-wide flow channel 4 upstream of the turbulence generator 5. The headbox 1 for a machine for producing a fibrous web can be flowed through by a fibrous suspension having a flow direction 18. It has a machine-wide flow channel 4, which is directly in front of a turbulence generator 5. The turbulence generator 5 is immediately followed by a nozzle 6. The machine-wide flow channel 4 is characterized by a machine-wide opening area 10 in the direction of the pressure chamber 15, and for further limitation has a machine-wide wide flow wall and two side walls. Inside the flow channel 4, at least in the area of the opening area 10, a membrane 12 is arranged and sealingly connected, preferably outside the opening area 10, to the corresponding lower part 17.1 and/or upper part 17.2. In this example, the membrane 12 lies against the perforated opening area 10 and forms a plane. The pressure chamber 15 is designed to be pressure-tested so that it can accommodate the pressurized medium. The opening area 10 can extend across the width of the machine in the transverse direction CD or only over a partial width of the flow channel 4. The compressible medium serves as a pressure cushion to dampen the hydraulic pulsations in the fibrous suspension transmitted through the membrane 12 through the opening region 10. The damping device 17 is designed to be installed in a headbox 1 to dampen pulsations in a fibrous suspension flow.

In the example of Figure 4a, the damping device 17 is foldably connected to the headbox 1 via a joint 16 and the circumferential connecting element 40. The flow channel 4 is preceded by a pipe grid 3, which is connected directly to a transverse distribution pipe 2. However, the invention also extends to other known distribution systems, such as sectional feeds of the pulp suspension to the headbox 1, as used in dilution water headboxes (stock density-controlled headboxes).

To adjust the pressure in the pressure chamber 15, the damping device 17 includes at least one measuring system 24 for determining the position of the membrane 12.

The headbox 1 shown in Figure 4b differs from the headbox 1 in Figure 4a only in that the damping device 17 is opened. This position enables maintenance or replacement of the membrane 12 in a simple manner. 5a and 5b each show a section of a possible embodiment of an opening region 10 of the upper part 17.2 or the pressure chamber 15 of a damping device 17 in a simplified representation. 5a shows in a first variant an opening area 10 set back by an offset dimension 21 with a membrane 12 spanning a plane, which is sealingly connected outside the opening area 10 to the opening area 10 of the upper part 17.2 with fastening means, not shown. A cavity is formed between the membrane 12 and the opening region 10 of the pressure chamber 15.

5b shows in a second variant an opening area 10 set back by an offset dimension 21 with a membrane 12 spanning a plane, which is connected outside the opening area 10 of the upper part 17.2 with clamping elements 44, not shown. A cavity is formed between the membrane 12 and the opening area 10 of the upper part 17.2. The membrane 12 is deflected slightly away from the opening area, which creates a larger cavity.

Figure 6a and Figure 6b show a mounting tool 63 in top and corresponding side view in the flow direction MD for mounting a membrane 12 on the connecting element of the lower part 41;

The assembly tool 63 for assembly of a membrane 12 in a damping device 17 comprises several, preferably six, pull opening gripper elements 64, which can be connected to the pull openings 48 of the membrane 12 and at the same time the assembly tool 63 with at least one assembly tool attachment element 67, which is connected to a complementary assembly tool holding element 62 Lower part 17.1 of the damping device 17 can be connected.

In the illustrated embodiment, the assembly tool has a cross element 65 for connecting the pull opening gripper elements 64 and a lever element 66 for applying the force by the operator. 7 shows a cross section through a damping device 17 according to the invention in the area of a possible embodiment of a damping device 17 and a flow channel 4. The connecting element 40 is also shown. The membrane 12 is arranged and clamped between the damping device 17 and the flow channel 4. The membrane 12 is supported in the opening area 10 of the damping device 17 by fixed areas between the openings 11 and is in operative connection via the openings 11 with the pressure chamber 15 and the compressible medium contained in the pressure chamber 15 and as well as the fibrous suspension flow in the flow channel 4, whereby the flow direction 18 of the fibrous suspension flow is simplified, shown in dotted lines.

7 further shows an alternative embodiment of the damping device 17 with two openings 11 in the opening area 10. An embodiment with a non-contact measuring system 24 is also shown; it is also conceivable to have an embodiment with two or three non-contact measuring systems 24 here. With multiple versions, there is redundancy and the non-contact measuring systems 24 are integrated into the digital control system for improved control.

It is advantageous if the measuring systems 24 with their measuring beams 25 are directed at different openings 11 of the damping device 17 and thus at different deflections or positions of the membrane 12 in the unsupported area. It is also advantageous if, in these areas with measuring beams 25, a reflection-increasing coating or a reflection-increasing plating is provided on the surface of the membrane 12 facing the measuring system 24 in order to reflect the measuring beam 25 back to the measuring system 24 as accurately as possible.

Figure 7 further shows an alternative embodiment of the damping device 17 and the flow channel 4. The pressure chamber 15 is designed in two parts, with the pressure chamber 15 comprising a first pressure chamber part 15.1 in the upper part 17.2 and a second pressure chamber part 15.2 in the lower part 17.1. The flow channel 4 and the second pressure chamber part 15.2 are together in the lower part

17.1 includes. The two pressure chamber parts 15.1 and 15.2 include the compressible medium, as in the alternative embodiments.

The damping device 17 further comprises an integrated pressure chamber connection 26, arranged such that the first pressure chamber part 15.1 in the damping device 17 and the second pressure chamber part 15.2 are connected. With this arrangement, a space-saving integration of the damping device 17 in a headbox 1 is conceivable. The pressure chamber connection 26 is designed to be congruent in the lower part 17.1, upper part 17.2 and membrane 12.

1 headbox

2 cross distribution pipe

3 pipe grids

4 flow channel

5 turbulence generators

6 nozzle

8 Fiber suspension feed

9 parallel area

10 opening area

11 openings

12 membranes

14 membrane thickness

15 pressure chamber

16 connecting element, joint

17 damping device

17.1 Lower part

17.2 Top 18 flow direction

21 offset dimension

24 measuring device

25 measuring beam

26 Integrated pressure chamber connection

27 Reflection-increasing coating or plating of the membrane

30 reinforcement ribs in the transverse direction on the lower part

31 transverse reinforcement ribs on the top

32 transport openings in the upper part

40 Circumferential connecting element, preferably flange

41 lower flange part

42 flange top

43 bolts or screw connection

43' hole or threaded hole for bolt or screw connection

44 clamping element

45 clamping system, area with increased surface roughness

46 spacer plate

47 recesses in the upper part 17.2 for the clamping elements 44

48 tension opening in the membrane

49 recess in the connecting element 40 for the membrane 12

50 floor (level)

51 stand element

60 pull/mounting opening

61 mounting bracket

62 assembly tool holding element

63 assembly tool

64 draw opening gripper element

65 cross element

66 lever element

67 assembly tool holding element

68 adjustment elements CD transverse direction

D1 diameter of the clamping openings

D2 Diameter of the pull or mounting openings KB Clamping width, width of the circumferential area of the clamping system 45

MD machine direction

SA hole distance from flange to hydraulic chamber

T1 division, distance between the opening centers z height direction in the coordinate system

Claims

Damping device (17) for use in a headbox (1) of a machine for producing a fibrous web, for damping pulsations in a fibrous suspension flow, comprising a lower part (17.1), an upper part (17.2) and a membrane (12), the lower part (17.1), the upper part (17.2) and the membrane (12) can be connected to one another and, wherein the lower part (17.1) comprises a flow channel (4) and, wherein the upper part (17.2) comprises a fillable pressure chamber (15) and, where the pressure chamber (15) and the flow channel (4) each comprise an opening region (10) that is essentially congruent and parallel to one another and, wherein the membrane (12) is sealingly arranged between the lower part (17.1) and the upper part (17.2), such in that the opening areas (10) of the pressure chamber (15) and the flow channel (4) are sealed against one another, characterized in that the lower part (17.1), the upper part (17.2) and the membrane (12) comprise a complementary connecting element (40). and that the connecting element (40) is designed such that the lower part (17.1) can be non-positively connected to the upper part (17.2) and that the connecting element (40) of the lower part (17.1) has several clamping elements (44), preferably several rotating ones Clamping bolts (44), which are suitable for positively prestressing the membrane (12). Damping device (17) according to claim 1, characterized in that the pressure chamber (15) has a non-contact measuring system (24), preferably a laser measuring system (24) or an ultrasonic measuring system (24) or a radar measuring system (24), for continuously measuring the position of the membrane (12) includes and that the non-contact measuring system (24) can be connected to a regulation and/or control device in such a way that a pressure in the pressure chamber (15) is continuously regulated.

3. Damping device (17) according to claim 1 or 2, characterized in that the connecting element (40) in the lower part (17.1) comprises a plurality of adjustment elements (68), preferably conical stud bolts (68).

4. Damping device (17) according to one of the preceding claims, characterized in that the connecting element (40) comprises a pressure-resistant, running, in particular multi-part, spacer plate (46) and is arranged such that the lower part (17.1) and the upper part (17.2) create a force-fitting connection.

5. Damping device (17) according to one of the preceding claims, characterized in that the connecting element (40) comprises a clamping system (45) for flat and non-positive clamping of the membrane (12), preferably in such a way that a force-induced positive connection between the upper part (17.2 ), membrane (12) and lower part (17.1).

6. Damping device (17) according to claim 5, characterized in that the clamping system (45) has a surface structure (45) integrated on the upper part (17.2) and/or a surface structure (45) integrated on the lower part (17.1) and/or a separate one circumferential clamping plate with integrated surface structure (45) and / or an area with increased surface roughness (45) provided on the surface of the membrane (12) has a positive fit Connection is designed such that the clamping system (45) clamps the membrane (12) by a positive and non-positive connection. Damping device (17) according to one of the preceding claims, characterized in that the upper part (17.2) of the damping device (17), at least in the area of the connected membrane (12), can be hingedly connected to the lower part (17.1). Membrane (12) for use in a damping device (17) according to claim 1, characterized in that the membrane (12) has a shape which is essentially complementary to the connecting element (40) of the damping device (17), preferably flat when installed, and the Opening area (10) completely seals, and that the membrane (12) distributed over its circumference, comprises a plurality of clamping openings (48), arranged in such a way that the clamping openings (48) are arranged in a complementary manner to the clamping elements (44) of the damping device (17). . Membrane (12) according to claim 8, characterized in that the membrane (12) extends over half, preferably over a quarter, of its circumference, preferably on at least one, two or three sides, in addition to the clamping openings (48) at least two, preferably includes several pull or assembly openings (60). Membrane (12) according to claim 9, characterized in that the pulling or mounting openings (60) are arranged centrally between the clamping openings (48). Membrane (12) according to one of claims 9 to 10, characterized in that the pulling or mounting openings (60) are arranged in line with the tensioning openings (48) or that the pulling or mounting openings (60) are arranged offset from the tensioning openings (48) towards the edge of the membrane (12). are.

12. Membrane (12) according to one of claims 8 to 11, characterized in that the membrane (12) has at least one area (27) with a reflection-increasing coating (27) or reflection-increasing plating (27) on the opening area (10) of the Upper part (17.2) facing side, preferably on at least one opening (11) of the opening area (10) assigned to the non-contact measuring system (24).

13. Membrane (12) according to one of claims 8 to 12, characterized in that the membrane (12) comprises mounting tabs (61) on its circumference.

14. Headbox (1) for a machine for producing a fibrous web, through which a fibrous suspension having a flow direction (18) can flow, comprising at least one fibrous suspension inlet (8) for supplying the headbox (1) with a fibrous suspension and a damping device (17) , characterized in that the damping device (17) is designed according to claim 1 and that the damping device (17) is provided in the at least one fibrous suspension inlet (8), before the fibrous suspension is divided in the transverse direction (CD).

15. Headbox (1) for a machine for producing a fibrous web, from a fibrous suspension having a flow direction (18). can be flowed through, comprising at least one machine-wide flow channel (4), which is upstream of a turbulence generator (5) and a nozzle (6) following the turbulence generator (5) and a damping device (17), characterized in that the damping device (17) according to claim 1 and that the damping device (17) is provided in the machine-wide flow channel (4), immediately in front of the turbulence generator (5), and that the damping device (17) extends essentially over the entire width of the machine-wide flow channel (4). Assembly tool (63) for assembly of a membrane (12) according to claim 8, wherein the membrane (12) comprises pull or assembly openings (48), in a damping device (17) according to claim 1, characterized in that the assembly tool (63) at least two, preferably several, in particular six, pull opening gripper elements (64), which can be connected to the pull or assembly openings (48) of the membrane (12), and that the assembly tool (63) comprises at least one assembly tool attachment element (67), which is connected to the Lower part (17.1) of the damping device (17) can be connected, preferably with an assembly tool holding element (62) which is complementary to the assembly tool attachment element (67) and is included in the lower part (17.1). Method for mounting a membrane (12) according to claim 8 in a damping device (17) according to claim 1, characterized in that a. the clamping openings (48) of the membrane (12) are connected to the clamping elements (44) of the lower part (17.1) on the opposite sides with the tension or assembly openings (60); b. an assembly tool (63) is connected to the pull or assembly openings (60) of the membrane (12); c. the assembly tool (63) with an included assembly tool attachment element (67) is connected to the lower part (17.1) of the damping device (17); d. the assembly tool (63) is tensioned in such a way that the clamping openings (48) on the side with the pulling or assembly openings (60) can be connected to the corresponding clamping elements (44) of the lower part (17.1) of the damping device (17).