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

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

[0001] Damping device and membrane for a headbox of a machine for producing a fibrous web

[0002] 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 are connectable 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 region which is essentially congruent and parallel to one another and wherein the membrane is arranged sealingly between the lower part and the upper part in such a way that the opening regions of the pressure chamber and the flow channel are sealed against one another.

[0003] 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.

[0004] The membrane serves to separate the medium in the fillable pressure chamber from the fiber suspension conveyed in the flow channel. To dampen pulsations in the fiber suspension flow, the membrane is held in a domed position by a controlled pressure in the pressure chamber, allowing it to float in the fiber suspension.

[0005] Devices of this type are known. Documents DE2307849 B1, DE2744512 A1, DE3003532 A1, and US4030971 A each disclose a headbox with a pulsation damper for damping hydraulic vibrations in the fiber 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 that is arranged between the fiber suspension and a pressure cushion. In the first variant, the membrane cuts through the transverse distribution pipe almost diagonally, viewed in cross-section, so that the fiber suspension flow hits the membrane directly at an acute angle. This can limit the damping effect and cause hydraulic disturbances. The design effort here is considerable.In addition, the usable coupling area between the membrane and the pressure cushion depends on the dimensioning of the cross-distribution pipe and is therefore not freely selectable.

[0006] This also applies to the second disclosed variant with an external damper in the headbox inlet line, where the size of the membrane depends on the size, i.e., the diameter, of the headbox inlet line. Furthermore, the pulsation damper is located a great distance from the headbox nozzle. This can lead to new pulsations that are no longer dampened. The damping effect is also less effective there.

[0007] Further disadvantages in designs that correspond to the state of the art shown are the proposed multi-stage connecting elements and corresponding designs of the membrane.

[0008] The disadvantages are particularly evident in the assembly and maintenance of the diaphragm. The proposed multi-stage connecting elements consist of a first connecting element for the diaphragm and a further connecting element for the pressure chamber. Furthermore, the first connecting element is designed in such a way that the diaphragm is held in position and pre-tensioned using 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 good sealing. The further connecting element, which connects the upper part to the lower part, also creates a final seal against the environment. Another disadvantage of a multi-stage connecting element is the high number of screw connections that have to be loosened and / or tightened for initial assembly and maintenance, which is time-consuming.

[0009] Another disadvantage is the pre-adjustment of the membrane pre-tension for optimal damping; this is very complex to adjust and calibrate, as the membrane pre-tension is undefined and must be adjusted by the assembly personnel using different methods and tools.

[0010] Another disadvantage is that the position of the diaphragm is controlled by a mechanical regulator that holds the diaphragm in position. Position control is achieved by a continuous, defined filling flow into the fillable pressure chamber. This lifts the diaphragm toward the fiber suspension, creating an air leakage flow that continuously escapes from the pressure chamber through a discharge line into the environment. The mechanical mechanism achieves position control by appropriately shaping a pressure plate on the diaphragm, by throttling the filling and discharge lines, and by the diaphragm's own weight.

[0011] Equally disadvantageous is the position control of the diaphragm based on differential pressure measurement between the pressure chamber and the flow channel. Accurate differential pressure measurement is difficult because high measurement resolution is required and the differential pressure is measured between a compressible medium, such as air, and the fiber suspension.

[0012] The diaphragm itself also influences the hydraulic system through its shape, thus influencing the flow itself. Differential pressure control maintains a constant tension on the diaphragm. This is particularly problematic due to changes in the diaphragm material over time, as, for example, a gradual change in the diaphragm material's elastic modulus affects the position and thus the damping properties of the diaphragm.

[0013] 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.

[0014] 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 life can be achieved.

[0015] The problem is solved by features of the independent claims.

[0016] 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 force-fitting manner and that the connecting element of the lower part comprises a plurality of clamping elements, preferably a plurality of circumferential clamping bolts, which are suitable for pre-tensioning the membrane in a form-fitting manner.

[0017] Advantageously, the connecting element is designed in such a way that a force-locking connection between the lower and upper parts can be achieved, and, likewise, with the same connecting element, a form-locking connection with the membrane can be achieved simultaneously through the tensioning elements. Advantageously, a connecting element designed according to the invention can achieve improved assembly and maintainability, as well as an extended service life.

[0018] The membrane must be slightly pre-stressed during operation so that temperature expansion, swelling and extrusion effects are compensated by clamping the membrane between the lower and upper parts during operation.

[0019] For this purpose, the tensioning elements are arranged circumferentially at a distance or pitch into which the membrane is suspended under tension before the upper part is mounted.

[0020] Advantageously, the preload of the diaphragm is adjusted by a combination of the diaphragm and the position of the clamping elements. No readjustment of the diaphragm preload is required, as the initial preload adjustment and continuous measurement of the diaphragm position allow the pressure in the fillable pressure chamber to be precisely adjusted to the pulsations occurring during operation, with essentially no time lag.

[0021] 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.

[0022] Advantageously, the position measurement is carried out without contact, which means reduced or no wear of the membrane at the measuring point and thus improves maintainability.

[0023] Furthermore, accuracy can be increased by a high-resolution, non-contact measuring system, which can be integrated into the pressure chamber thanks to a compact and simple design. The measurement signal can also be used for further predictive maintenance of upstream equipment, as the position can be directly transferred into pressure fluctuations, thus recording a long-term trend of changes.

[0024] 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 lead to a reduction in the material stress on the membrane itself.

[0025] In an alternative embodiment, the damping device is characterized in that the contactless measuring system can be connected to a control and / or regulation device such that a pressure in the pressure chamber is continuously regulated.

[0026] Advantageously, the position of the diaphragm can be measured continuously using a non-contact, high-resolution measurement signal without affecting the measuring system itself. The continuous measurement signal is further processed directly into a control and regulation device, and high-resolution control devices in a filling line and / or a discharge line of the fillable pressure chamber continuously regulate the pressure during operation depending on the position of the diaphragm. The control devices used can be, for example, throttles and / or valves adjustable with electric actuators.

[0027] Advantageously, a non-contact measuring system for position determination simplifies the calibration process during assembly by providing a control and regulation device that can be continuously modified 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 a quadrangular, preferably rectangular or square, circumferential flange connection, surrounding the opening area and the pressure chamber, and in that the connecting element comprises a lower flange assigned to the lower part and an upper flange assigned to the upper part and complementary to the lower flange.

[0028] Advantageously, the connection is designed as a flange connection with screws, whereby holes with threads in the lower part or a through hole for fixing by bolts with a lock nut can be provided in the lower and upper parts.

[0029] By tightening the screws to a sufficiently high torque, a frictional connection between the lower part and the upper part can be achieved.

[0030] In an alternative embodiment, the damping device is characterized in that the connecting element is designed such that, in a closed state of the damping device, the lower part and the upper part completely enclose the membrane.

[0031] In an alternative embodiment, the damping device is characterized in that the connecting element of the upper part for the plurality of clamping elements, preferably a plurality of circumferential clamping bolts, comprises at least one complementary recess for the clamping elements, preferably for each clamping element a complementary recess, preferably a bore, which is suitable for providing a positive connection of the clamping elements and the recess when connecting the lower part to the upper part.

[0032] In an alternative embodiment, the damping device is characterized in that the connecting element in the lower part comprises several adjustment elements, preferably 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 fastening for the openings of the mounting tabs in the diaphragm.

[0033] 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 region of an overlap with the membrane, and that the recess for the membrane is designed with an offset dimension of less than the small thickness of the membrane.

[0034] Advantageously, the connecting element of the lower part and / or the upper part is designed to be reduced in the area of ​​the flow chamber to create space for the diaphragm. The reduction is advantageously designed to be smaller than the thickness of the diaphragm. The height of the reduction corresponds to the required clamping force for the diaphragm.

[0035] In an alternative embodiment, the damping device is characterized in that the connecting element comprises a pressure-resistant, continuous, in particular multi-part, spacer plate and is arranged such that the lower part and the upper part produce a force connection.

[0036] 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 to the thickness of the membrane, so that the smaller thickness of the spacer plate creates a predefined clamping of the membrane.

[0037] Furthermore, the spacer plate can ensure a strong force connection between the lower part and the upper part and thus ensure a clearly defined tightening torque of the flange screws.

[0038] Furthermore, the spacer plate prevents the membrane from being clamped too tightly, which could lead to its destruction. In an alternative embodiment, the damping device is characterized by the fact that the connecting element simultaneously comprises a clamping system for clamping the membrane flatly and force-fittingly.

[0039] When the damping device is closed, a clamping system running around the circumference ensures a positive, point-to-point connection between the diaphragm and the tensioning elements, either through a flat, force-locking connection or a force-induced positive connection between the diaphragm and the lower and upper sections of the damping device. This relieves the load on the point-to-point connections during continuous operation and provides a more durable solution.

[0040] In addition to fixing the membrane, the connecting element also provides sealing against the environment through only one common, preferably single, connecting element.

[0041] 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, since otherwise the membrane will be elongated by extrusion effects and lose its required pre-tension or, in extreme cases, be damaged by an excessive clamping force.

[0042] The connecting element ensures simple and error-free assembly by operating or maintenance personnel without the need for additional calibration and measuring devices.

[0043] 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 35 mm, preferably less than or equal to 25 mm.

[0044] Advantageously, the clamping system is integrated into the lower part and / or the lower part, so that the membrane resting on the lower part is clamped in a form-fitting manner by the upper part with a predefined clamping force. In an alternative embodiment, the damping device is characterized in that the clamping system is formed by a surface structure integrated into the upper part and / or a surface structure integrated into 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 with increased surface roughness, such that the clamping system clamps the membrane through a form-fitting and force-fitting connection.

[0045] Advantageously, in the intended clamping system with the corresponding clamping width, a corresponding shape achieves not only a force-fitting connection between the components but also a positive connection through the surface structure. For this purpose, the respective surfaces in the upper part, lower part and / or on the membrane in the area of ​​the clamping system are adapted. 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 allow the use of a membrane with a smaller thickness in a damping device designed for a larger thickness.

[0046] To reduce the bolt forces required for the force-locking connection between the lower and upper sections, the distance SA of the bolts and / or screw connections to the pressure chamber or flow channel is kept as small as possible. It is also advantageous if the clamping width can be kept small.

[0047] 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 material expenditure 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 body with gas inclusions, and can be brought into operative connection with a regulating and / or control device for adjusting a pressure in the pressure chamber, preferably as a function of 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 body with gas inclusions, for example a foam.

[0048] 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.

[0049] In an alternative embodiment, the damping device is characterized in that each opening is assigned an individual membrane.

[0050] In an alternative embodiment, the damping device is characterized in that a single membrane is assigned to the opening area. This also applies if the opening area comprises several sub-areas.

[0051] In an advantageous further development, the upper part of the damping device is designed to be hinged, at least in the area of ​​the connected membrane. Hinges can be provided for this purpose, connecting the first and / or second flow wall to the headbox. This allows for easy maintenance or replacement of the membrane.

[0052] A membrane according to the invention for use in a damping device according to the invention is characterized in that the membrane has a flat shape that is substantially complementary to the connecting element of the damping device and completely seals the opening area, and in that the membrane comprises a plurality of clamping openings distributed over its circumference, arranged such that the clamping openings are arranged complementarily to the clamping elements of the damping device.

[0053] In an alternative embodiment, the membrane is characterized in that the membrane comprises, in addition to the tensioning openings, several tension or mounting openings over half, preferably over a quarter, of its circumference, preferably on at least one, two or three sides.

[0054] Advantageously, in addition to the tensioning openings, further tension or mounting openings are provided over a certain section of the circumference or on at least one side of the flat membrane, such that the tension or mounting openings are only used when mounting the membrane in the damping device and are without function when closed.

[0055] 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.

[0056] Advantageously, the clamping openings can be made round by directly adjusting the preload, whereby elongated holes or oval opening shapes are provided if the preload of the membrane is adjustable.

[0057] 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 30 mm, preferably less than or equal to 20 mm.

[0058] In an alternative embodiment, the membrane is characterized in that the centers of the clamping openings are spaced from each other at a distance of less than or equal to 100 mm, preferably less than or equal to 80 mm.

[0059] Advantageously, the distance T1 or the pitch T1 is designed with a smaller distance in the case of a round design of the clamping openings for better force distribution in the membrane.

[0060] 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 10 mm, preferably less than or equal to 8 mm.

[0061] In an alternative embodiment, the membrane is characterized in that the tension or mounting openings are arranged centrally between the tension openings.

[0062] In an alternative embodiment, the membrane is characterized in that the tension or mounting openings are arranged in line with the tension openings or that the tension or mounting openings are arranged offset from the tension openings in the direction of the edge of the membrane.

[0063] In an alternative embodiment, the membrane is characterized in that the material of the membrane is an elastomer, wherein the elastomer is selected from the following group: perfluoro rubber-FFPM, fluoro rubber-FPM, tetrafluoroethylene, fluoropropylene rubber-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.

[0064] Thermoplastics such as tetrafluoroethylene Teflon, polyphenylene sulfone PPSU, polycarbonate PC, and polyethylene PE may also be suitable. Ethylene propylene polymer EPDM and fluororubber FPM are particularly preferred as membrane materials.

[0065] The hardness of the membrane material can be greater than 40 ShoreA to reduce the tendency to flutter.

[0066] For lower demands on pulsation damping, it is also conceivable for the diaphragm material to be made of metal, particularly stainless steel, and preferably a composite material. The composite material can be a coated metal sheet.

[0067] 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.

[0068] In an alternative embodiment, the membrane is characterized in that the membrane comprises at least one region with a reflection-enhancing coating or plating on the side facing the opening region of the upper part, preferably at at least one opening assigned to the non-contact measuring system.

[0069] In an alternative embodiment, the membrane is characterized in that the membrane is free of mounting tabs at its circumference.

[0070] In an alternative embodiment, the membrane is characterized in that the membrane comprises mounting tabs on its circumference.

[0071] Advantageously, at least four, preferably six or eight, protruding mounting tabs distributed around the circumference are included on the diaphragm. Each mounting tab includes at least one adjustment or positioning opening for rough initial alignment during assembly and / or maintenance. Advantageously, mounting tabs are provided on the diaphragm in such a way that single-person assembly by a member of the operating and / or maintenance personnel is possible. In a first assembly step, the mounting tabs are hooked with their adjustment or positioning openings onto the provided adjustment elements, preferably positioning pins, of the lower part of the damping device, so that the diaphragm is roughly aligned and held above the flow channel, preventing the diaphragm from falling into the flow channel.

[0072] In a second step, the clamping openings on one of the opposite sides equipped with tension or mounting openings are connected to the clamping elements of the lower part. The corresponding step is repeated once or twice for the remaining sides without tension or mounting openings. In a further step, an assembly tool with an assembly tool holder is connected to the lower part, and then the tension or mounting openings of the membrane are connected to a tension opening gripper element. The person then tightens the assembly tool so that the remaining clamping openings are connected to the corresponding clamping elements.

[0073] This gives the diaphragm a predefined, fixed, and unchangeable preload. The final assembly of the upper part of the damping device takes place without any further interaction with the diaphragm.

[0074] In an alternative embodiment, the membrane is characterized in that the membrane comprises, on the surface facing the upper part, a circumferential region with increased surface roughness for the clamping system and in that the region lies within the area spanned by the clamping openings and in that the region has a circumferential width in the direction of the center of the spanned area of ​​less than or equal to 35 mm, preferably less than or equal to 25 mm. In an alternative embodiment, the membrane is characterized in that the membrane is essentially designed as a quadrangular 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.

[0075] 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 in that the damping device is provided in the at least one fibrous suspension inlet, before a division of the fibrous suspension in the transverse direction.

[0076] The invention avoids the disadvantages of the known headboxes, particularly with regard to the damping of hydraulic pulsations.

[0077] 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 arranged upstream of a turbulence generator and a nozzle downstream of 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 upstream of the turbulence generator, and that the damping device extends substantially over the entire width of the machine-wide flow channel.

[0078] The solution is structurally very simple and also very effective, since the damping of the hydraulic pulsations takes place directly upstream of the turbulence generator. Furthermore, this solution is adaptable to different damping requirements for the flow pulsations. For example, one flow wall or both flow walls can be equipped with the damping device. An assembly tool for mounting a diaphragm 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 diaphragm, and in that the assembly tool comprises at least one assembly tool attachment element, which can be connected to the lower part of the damping device by means of an assembly tool holding element complementary to the assembly tool attachment element.

[0079] 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 on the opposite sides provided with the tension or mounting openings are connected to the clamping elements of the lower part; b. an assembly tool is connected to the tension or mounting openings of the membrane; c. the assembly tool is connected to a first assembly tool holding element of the damping device by means of an enclosed assembly tool attachment element; d. the assembly tool is clamped in such a way that the clamping openings on the side provided with the tension or mounting openings are connected to the corresponding clamping elements of the damping device.

[0080] The invention expressly extends to embodiments that are not defined by feature combinations from explicit references to the claims, whereby the disclosed features of the invention can be combined with one another in any way—as long 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.

[0081] It shows

[0082] Figure 1 is a side view in the flow direction MD of a damping device 17 arranged in the fiber suspension inlet 8 of a headbox 1 in a simplified representation;

[0083] Figure 2 is a plan view in the z-direction of a damping device 17 arranged in the fiber suspension inlet 8 of a headbox 1 in a simplified representation with a view of a closed upper part 17.2;

[0084] Figure 3 is a plan view in the z-direction of a damping device 17 arranged in the fiber 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;

[0085] Figure 4a shows an embodiment of a headbox according to the invention with a damping device in a simplified representation;

[0086] Figure 4b shows an embodiment of a headbox according to the invention according to Figure 4a with a pivoted damping device in a simplified representation;

[0087] Figure 5a shows a first variant of an opening area 10 of the pressure chamber 15 with membrane 12 in a simplified representation;

[0088] Figure 5b shows a second variant of an opening area 10 of the pressure chamber 15 with membrane 12 in a simplified representation;

[0089] Figure 6a shows an assembly tool 63 in plan view for mounting a membrane 12 on the connecting element of the lower part 41;

[0090] Figure 6b shows an assembly tool 63 in a side view in the flow direction MD for mounting 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.

[0091] Corresponding elements of the exemplary embodiments in the figures are provided with the same reference numerals. The functions of such elements in the individual figures correspond to one another, unless otherwise stated and unless contradictory. A repeated description is therefore omitted. It is also pointed out that the differing features of the exemplary embodiments shown can be interchanged and combined with one another. The invention is therefore not limited to the combinations of features shown in the exemplary embodiments shown.

[0092] To illustrate the individual directions, a Cartesian coordinate system has been created. The x-direction represents the longitudinal direction, 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.

[0093] Figure 1 shows a side view in the flow direction MD of a damping device 17, which is arranged in the fiber suspension inlet 8 of a headbox 1 in a simplified representation.

[0094] The fiber suspension flows through the inlet 8, which is only partially shown, in the flow direction 18 shown by an arrow.

[0095] The damping device 17 comprises several elements, including a lower part 17.1 and a preferably removable upper part 17.2. Furthermore, the damping device 17 comprises a replaceable or interchangeable membrane 12, which is subject to wear during operation of the damping device 17 and should be replaced regularly.

[0096] The lower part 17.1 of the damping device 17 comprises a flow channel 4, which transports the fiber suspension 18 in a preferably circular, convex, or semicircular cross-section. For reasons of strength, the lower part 17.1 is reinforced across 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 plane 50 or a floor 50 for force introduction. Likewise, the lower part 17.1 can optionally also establish the connection to the base 50 via support elements 51.

[0097] As a further alternative embodiment, the lower part can also be arranged freely suspended on another component, such as the fiber suspension inlet 8.

[0098] The removable upper part 17.2 of the damping device 17 comprises a fillable pressure chamber 15, which, when closed with the lower part 17.1, can be filled with a compressible medium. For example, air, a liquid with gas inclusions, or a solid with gas inclusions can be used as the compressible medium.

[0099] For reasons of strength, the upper part 17.2, similar to the lower part 17.1, is reinforced across the machine direction MD with at least one reinforcing rib 31, preferably a plurality of reinforcing ribs 31, in the transverse direction CD. Furthermore, the reinforcing ribs 31 can be provided with a plurality of transport openings 32, which are suitable, for example, for serving as a receptacle for a crane to remove the upper part 17.2 from the lower part 17.1 for the installation and maintenance of a membrane 12 located therebetween.

[0100] In a "closed state" of the damping device 17, the lower part 17.1, the upper part 17.2, and the intermediate membrane 12 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.

[0101] 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 which is essentially congruent and parallel to one another. The pressure chamber 15 is formed in a preferably circular or convex or semicircular cross-section.

[0102] 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 each other in a closed state.

[0103] 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.

[0104] "Circular" means that the flange, viewed from above, has a closed circular or multi-sided circumference to ensure a uniform connection between the lower and upper parts. Advantageously, the flange is designed as a quadrangular or quadrilateral shape, for example, rectangular (as shown) or square.

[0105] Furthermore, in a closed state, the connecting element 40, the membrane 12 and the two opening areas 10 are arranged in an area 9 which is essentially parallel to one another.

[0106] The connecting element 40 comprises 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 and the upper flange 42 can be designed with several bolt connections 43 (shown on the left in the image) and / or screw connections 43 (shown on the right in the image). If it is a bolt connection 43, the upper flange 42 and lower flange 41 comprise bores 43' at the corresponding locations (see Figure 3). If the connection is designed as a screw connection 43, a threaded bore 43' (see Figure 3) is advantageously provided in the lower flange 41.

[0107] In order to reduce the screw forces 43 for a force-locking connection of the lower part 17.1 with the upper part 17.2, the distance SA to the pressure chamber 15 or the flow channel 4 is kept as small as possible.

[0108] In the illustrated embodiment, 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 circular or elongated, for example. Figure 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.

[0109] Furthermore, the illustrated embodiment comprises a non-contact measuring system 24 arranged within the pressure chamber 15.

[0110] The non-contact measuring system 24 can be implemented as an inductive or capacitive or optical or acoustic electromagnetic measuring system 24. An inductive measuring system can also be used reliably and advantageously in a contaminated pressure medium.

[0111] 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.

[0112] 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 pressures, complex commissioning procedures can be reduced or completely eliminated. Likewise, a very precise initial adjustment of the diaphragm 12 and calibrations for converting pressure into length can be reduced or completely eliminated.

[0113] The measuring system 24 is arranged and aligned within the pressure chamber 15 such that continuous measurement is carried out with a measuring beam 25, which is directed through the opening area 10 and / or an opening 11 onto the membrane 12 and reflected there. The measuring system 24 itself can be connected to a higher-level control and regulation device via cabling accessible outside the pressure chamber 15 or a radio signal, such that the pressure in the pressure chamber 15 is continuously regulated.

[0114] 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 diaphragm 12 experiences constant wear during operation due to the constant up-and-down movement required to dampen the pulsations in the fiber suspension flow in the flow channel 4. Due to this wear, the material of the diaphragm 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 reliably compensated for by readjusting the pressure in the pressure chamber 15 during operation, without requiring any further maintenance measures. This advantageously enables an extension of the operating phase and proactive planning for a necessary replacement of the diaphragm 12.

[0115] The non-contact measuring system 24 detects the position of the diaphragm 12 through one or more opening areas 10 and / or openings 11, i.e., in the unsupported area of ​​the diaphragm 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 statically sealed, thus preventing any leakage from the pressure chamber 15 through the measuring system 24 into the environment.

[0116] The non-contact measuring system 24 provides the measuring signals for the control system, which regulates the pressure of the compressible medium in the pressure chamber 15 and thus enables adjustment of the preload and position of the membrane 12 in order to optimally adapt to the boundary conditions present in the fiber suspension flow in the flow channel 4 with regard to the damping properties.

[0117] The membrane 12 comprises, on the surface facing the pressure chamber 15, preferably in the opening region 10 or at least one opening 11, a reflection-enhanced region compared to the material of the membrane 12. The reflection-enhanced region is preferably designed as a reflection-enhancing coating or a plating on the surface of the membrane 12 facing the pressure chamber 15.

[0118] The connecting element 40 is designed such that in a closed state of the lower part 17.1 and the upper part 17.2, the membrane 12 is completely enclosed by the connecting element 40.

[0119] The connecting element 40 of the lower part 17.1 or the lower flange 41 comprises a plurality of clamping elements 44, which are suitable for pre-tensioning the diaphragm 12 in a geometrically predefined position. The clamping elements 44 are designed, for example, as circumferential clamping bolts 44, 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.

[0120] The diaphragm 12 must be slightly prestressed during operation so that thermal expansion, swelling, and extrusion effects are compensated for by clamping in the clamping area 45 across a clamping width KB of the diaphragm 12 between the lower part 17.1 and the upper part 17.2 during operation. For this purpose, the clamping elements 44 are arranged circumferentially at a distance T1 or a pitch T1, into which the diaphragm is suspended under tension before the upper part is installed.

[0121] Advantageously, the preload of the diaphragm 12 is adjusted by a combination of the precisely manufactured diaphragm 12 and the exact position of the clamping elements 44. No readjustment of the preload of the diaphragm 12 is required, since the initial adjustment of the preload and continuous measurement 24 of the position of the diaphragm 12 advantageously allow the pressure in the fillable pressure chamber 15 to be precisely adjusted to the pulsations occurring in the flow channel 4 during operation, essentially with no time lag.

[0122] The connecting element 40 of the upper part 17.2 further comprises complementary recesses 47 for the plurality of clamping elements 44 in the lower part 17.1, for a preferably positive-locking enclosure of the clamping elements 44 in the closed state. For example, the complementary recesses 47 of the clamping elements 44 are designed as bores, which are designed to provide a receptacle when connecting the lower part 17.1 to the upper part 17.2.

[0123] The connecting element 40 of the upper part 17.2 further comprises, in the region of the pressure chamber 15 or the flow channel 4 or the opening region 10, a recess 49 in the upper part 17.2 for a clamping system 45, so that the region of the recess 49 is suitable for receiving the membrane 12 and for establishing a force-fitting connection with the connecting element 40 of the lower part 17.1, lower flange 41, in the remaining region of the connecting element 40 of the upper part 17.2, upper flange 42.

[0124] Advantageously, the connecting element 40 of the lower part 17.1 and / or the upper part 17.2 is designed with a recess 49 or an offset 49 in the area of ​​the flow chamber 4, 15 in order to form a space for the membrane 12. The reduction is advantageously designed to be 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 with increasing recess; if the recess 49 is smaller compared to the parallel area 9, the clamping force is increased.

[0125] Advantageously, the connecting element 40 comprises a pressure-resistant, continuous, 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.

[0126] 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 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.

[0127] 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 of the flange screws 43.

[0128] Furthermore, the spacer plate 46 prevents the clamping force in the clamping system 45 of the membrane 12 from being exceeded, which could lead to the destruction of the membrane 12.

[0129] The connecting element 40 further comprises a clamping system 45 with a clamping width KB, wherein the clamping system 45 is arranged such that the membrane 12 resting on the lower part 17.1 is clamped by the upper part 17.2 with a predefined clamping force in the clamping system 45. The clamping system 45 is advantageously arranged behind the clamping elements 44, viewed from the outside in the direction of the flow chamber 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. For this purpose, it is also advantageous if the clamping width KB can be kept small.

[0130] Furthermore, the parallel region 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 region 10 of the damping device 17 by fixed regions between the openings 11 and is operatively connected via the openings 11 to the pressure chamber 15 and the compressible medium contained in the pressure chamber 15, as well as to the fiber suspension flow in the flow channel 4, wherein the flow direction 18 of the fiber suspension flow is shown in a simplified, dotted line.

[0131] The lower part 17.1 or the lower flange 41 comprises at least one holding element 62 for an assembly tool 63 for mounting the membrane 12.

[0132] Figure 2 shows a plan view in the z-direction of a damping device 17 arranged in the fiber suspension inlet 8 of a headbox 1 in a simplified representation with a view of a closed upper part 17.2.

[0133] Figure 2 further 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.

[0134] The connecting element 40 of the upper part 17.2 and the lower part 17.1 is connected to each other by several circumferential screw connections 43.

[0135] The upper part 17.2 is shown with two reinforcing ribs 31 in the transverse direction CD.

[0136] Likewise, Figure 2 shows an alternative embodiment with three, preferably two or four, non-contact measuring systems 24; it is also conceivable to have a version with one or three non-contact measuring systems 24. In a multiple version, redundancy is provided, and the non-contact measuring systems 24 are integrated together into the control and regulation device for improved regulation.

[0137] It is advantageous if the measuring systems 24, with their measuring beams 25, are directed at different areas of the opening area 10 of the pressure chamber 15 or different openings 11, and thus at different deflections or positions of the membrane 12 in the unsupported area. Furthermore, it is advantageous if, in these areas with measuring beams 25, a reflection-enhancing coating 27 or a reflection-enhancing plating 27 is provided on the surface of the membrane 12 facing the measuring system 24 (see Figure 3) in order to reflect the measuring beam 25 back to the measuring system 24 as accurately as possible.

[0138] Figure 3 shows a plan view in the z-direction of a damping device 17 arranged in the fiber 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.

[0139] 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. They are arranged on the lower flange 41 corresponding to the pull and assembly openings 60 provided in the membrane 12. Likewise, the reflection-enhancing coatings 27 are shown at the corresponding locations, but at least at one location 27, on the surface of the membrane 12.

[0140] The spacer plate 46 for a predefined force-locking connection of the upper part 17.2 to 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 when assembling into a closed state, mobile or fixed adjustment elements 68, for example, positioning pins 68, can be provided in the lower flange 41 and upper flange 42. The adjustment elements 68 improve the positioning of the components relative to one another during assembly.

[0141] In the alternative variant shown in Figure 3, the membrane 12 is 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 an initial 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 the associated clamping elements 44 of the lower flange 41 takes place and thus the membrane 12 with its circumferential clamping openings 48 is hooked into the circumferential clamping elements 44.

[0142] The mounting bracket 61 shown in Figure 3 has a total of ten mounting brackets 61 all around, but only two, four, six or eight mounting brackets 61 are also conceivable.

[0143] The circumferential clamping system 45 has a circumferential clamping width KB and is designed congruently on the upper part 17.2, the membrane 12 and / or 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.

[0144] The clamping system 45 is advantageously arranged within the surface spanned by the clamping openings 48, and the circumferential clamping width KB in the direction of the center of the clamped surface is less than or equal to 35 mm, preferably less than or equal to 25 mm.

[0145] The membrane 12 is essentially designed as a rectangular 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.

[0146] The lower flange 41 also shows the enclosed bores or threaded bores 43' for receiving the bolts or screw connections 43.

[0147] Advantageously, additional tension or mounting openings 60 are provided on at least one-quarter, preferably one-half, of the circumference of the flat membrane in addition to the tension openings 48, such that the tension or mounting openings 60 are only used during assembly of the membrane 12 in the damping device 17. In the illustrated quadrangular embodiment, the membrane 12 comprises two sides with a plurality of tension or mounting openings 60.

[0148] In the illustrated embodiment, 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.

[0149] Advantageously, the clamping openings 48 can be designed in a round shape by directly adjusting the preload, whereby disadvantageous elongated holes or oval opening shapes are provided when the preload of the membrane 12 is adjustable.

[0150] 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 30 mm, preferably less than or equal to 20 mm.

[0151] In the illustrated embodiment, the clamping openings 48 are arranged at a distance T1 or a pitch T1 from one another, at a distance T1 of less than or equal to 100 mm, preferably less than or equal to 80 mm. The distances are measured from one center point of an opening to the next center point or another corresponding reference value.

[0152] In the illustrated embodiment, the pull or mounting openings 60 are designed with a diameter D2 of less than or equal to 10 mm, preferably less than or equal to 8 mm.

[0153] In the illustrated embodiment, the tension or mounting openings 60 are arranged on the corresponding sides of the membrane 12, centrally between the tension openings 48.

[0154] In an embodiment not shown, the tension or mounting openings 60 can be arranged in line with the centers of the clamping openings 48. In the illustrated embodiment, the tension or mounting openings 60 are arranged such that the centers of the tension or mounting openings 60 are offset from the centers of the clamping openings 48 toward the edge of the membrane 12.

[0155] Figure 4a shows a simplified representation of an embodiment of a headbox 1 with a damping device 17, wherein the damping device 17 is in the operating position and connected to the headbox 1. In this example, the headbox 1 is designed with a damping device 17, which is provided in a flow channel 4, preferably machine-wide, 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 located directly upstream of a turbulence generator 5. A nozzle 6 immediately follows the turbulence generator 5.The machine-wide flow channel 4 is characterized by a machine-wide opening area 10 in the direction of the pressure chamber 15, and has a machine-wide flow wall and two lateral walls for further delimitation. A membrane 12 is arranged inside the flow channel 4, at least in the area of ​​the opening area 10, and is 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 rests against the perforated opening area 10 and forms a plane. The pressure chamber 15 is pressure-resistant so that it can accommodate the pressurizable medium. The opening area 10 can extend across the machine width 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 fiber suspension transmitted through the membrane 12 through the opening area 10. The damping device 17 is designed for installation in a headbox 1 to dampen pulsations in a fiber suspension flow.

[0156] In the example of Figure 4a, the damping device 17 is hingedly connected to the headbox 1 via a joint 16 and the circumferential connecting element 40. A pipe grid 3 is arranged upstream of the flow channel 4 and is directly connected to a transverse distribution pipe 2. However, the invention also extends to other known distribution systems, such as sectional feeds of the fiber suspension to the headbox 1, as used in dilution water headboxes (stock density-controlled headboxes).

[0157] For adjusting the pressure in the pressure chamber 15, the damping device 17 comprises at least one measuring system 24 for determining the position of the diaphragm 12.

[0158] The headbox 1 shown in Figure 4b differs from the headbox 1 in Figure 4a only in that the damping device 17 is folded out. This position enables maintenance or replacement of the diaphragm 12 in a simple manner. Figures 5a and 5b each show a simplified representation of a section of a possible embodiment of an opening region 10 of the upper part 17.2 or of the pressure chamber 15 of a damping device 17. Figure 5a shows a first variant of an opening region 10 set back by an offset dimension 21 with a diaphragm 12 spanning a plane, which is sealingly connected outside the opening region 10 to the opening region 10 of the upper part 17.2 by fastening means not shown. A cavity is formed between the diaphragm 12 and the opening region 10 of the pressure chamber 15.

[0159] Figure 5b shows a second variant of 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 to 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, creating a larger cavity.

[0160] Figure 6a and Figure 6b show an assembly tool 63 in top view and corresponding side view in the flow direction MD for mounting a membrane 12 on the connecting element of the lower part 41;

[0161] The assembly tool 63 for assembling 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 can be connected to the lower part 17.1 of the damping device 17 by means of a complementary assembly tool holding element 62.

[0162] 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 operating personnel. Figure 7 shows a cross section through a damping device 17 according to the invention in the region of a possible embodiment of a damping device 17 and a flow channel 4. The connecting element 40 is also shown. The diaphragm 12 is arranged and clamped between the damping device 17 and the flow channel 4. The diaphragm 12 is supported in the opening region 10 of the damping device 17 by fixed areas between the openings 11 and is operatively connected via the openings 11 to the pressure chamber 15 and the compressible medium contained in the pressure chamber 15, as well as to the fiber suspension flow in the flow channel 4, wherein the flow direction 18 of the fiber suspension flow is shown in a simplified, dotted line.

[0163] Figure 7 further shows an alternative embodiment of the damping device 17 with two openings 11 in the opening area 10. Furthermore, a design with one contactless measuring system 24 is shown; it is also conceivable to have a design with two or three contactless measuring systems 24. In a multiple design, redundancy is provided, and the contactless measuring systems 24 are integrated into the digital control system for improved control.

[0164] It is advantageous if the measuring systems 24 are directed with their measuring beams 25 at different openings 11 of the damping device 17 and thus at different deflections or positions of the membrane 12 in the unsupported area. Furthermore, it is advantageous if, in these areas with measuring beams 25, a reflection-enhancing coating or a reflection-enhancing 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.

[0165] 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, wherein the pressure chamber 15 comprises 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 jointly arranged in the lower part

[0166] 17.1. The two pressure chamber parts 15.1 and 15.2 contain the compressible medium, as in the alternative embodiments.

[0167] 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. This arrangement allows for a space-saving integration of the damping device 17 into a headbox 1. The pressure chamber connection 26 is designed to be congruent in the lower part 17.1, the upper part 17.2, and the diaphragm 12.

[0168] 1 headbox

[0169] 2 cross distribution pipe

[0170] 3 pipe grids

[0171] 4 flow channel

[0172] 5 turbulence generators

[0173] 6 nozzle

[0174] 8 Fiber suspension inlet

[0175] 9 parallel area

[0176] 10 Opening area

[0177] 11 openings

[0178] 12 membranes

[0179] 14 Membrane thickness

[0180] 15 pressure chamber

[0181] 16 Connecting element, joint

[0182] 17 Damping device

[0183] 17.1 Lower part

[0184] 17.2 Upper part 18 Flow direction

[0185] 21 Offset dimension

[0186] 24 measuring device

[0187] 25 measuring beam

[0188] 26 Integrated pressure chamber connection

[0189] 27 Reflection-enhancing coating or plating of the membrane

[0190] 30 reinforcement ribs in transverse direction on the lower part

[0191] 31 reinforcement ribs in transverse direction on the upper part

[0192] 32 transport openings upper part

[0193] 40 Circumferential connecting element, preferably flange

[0194] 41 Flange base

[0195] 42 flange top

[0196] 43 Bolt or screw connection

[0197] 43' hole or threaded hole for bolt or screw connection

[0198] 44 clamping element

[0199] 45 Clamping system, area with increased surface roughness

[0200] 46 spacer plate

[0201] 47 Recesses in the upper part 17.2 for the clamping elements 44

[0202] 48 Clamping opening in the membrane

[0203] 49 Recess in the connecting element 40 for the membrane 12

[0204] 50 Floor (Level)

[0205] 51 Stand element

[0206] 60 pull / mounting opening

[0207] 61 Mounting tab

[0208] 62 Assembly tool holder element

[0209] 63 Assembly tools

[0210] 64 Pull opening gripper element

[0211] 65 Cross element

[0212] 66 Lever element

[0213] 67 Assembly tool holder element

[0214] 68 Adjustment elements CD transverse direction

[0215] D1 Diameter of the clamping openings

[0216] D2 Diameter of the pull or mounting openings KB Clamping width, width of the surrounding area of ​​the clamping system 45

[0217] MD Machine direction

[0218] SA Hole distance flange to hydraulic chamber

[0219] T1 pitch, 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), wherein the lower part (17.1), the upper part (17.2) and the membrane (12) are connectable 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, wherein the pressure chamber (15) and the flow channel (4) each comprise an opening region (10) that is substantially congruent and parallel to each other and, wherein the membrane (12) is arranged sealingly between the lower part (17.1) and the upper part (17.2) such that the opening regions (10) of the pressure chamber (15) and the flow channel (4) flow channel (4) are sealed against each other, 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 force-fitted to the upper part (17.2), and that the connecting element (40) of the lower part (17.1) comprises several clamping elements (44), preferably several rotating clamping bolts (44), which are suitable for positively pre-tensioning the membrane (12). Damping device (17) according to claim 1, characterized in that the pressure chamber (15) comprises 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), and that. the non-contact measuring system (24) can be connected to a control and / or regulation 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 several adjustment elements (68), preferably conical studs (68).

4. Damping device (17) according to one of the preceding claims, characterized in that the connecting element (40) comprises a pressure-resistant, rotating, in particular multi-part, spacer plate (46) and is arranged such that the lower part (17.1 ) and the upper part (17.2) form a force-fit 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 planar and force-fit clamping of the membrane (12), preferably such that a force-induced positive locking is formed between 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) is provided by 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 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) in a form-fitting manner. The connection is designed such that the clamping system (45) clamps the membrane (12) by means of a positive and force-fit connection. A 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), is hingedly connectable to the lower part (17.1). A membrane (12) for use in a damping device (17) according to claim 1, characterized in that the membrane (12) has a shape substantially complementary to the connecting element (40) of the damping device (17), preferably flat in the installed state, and completely seals the opening area (10), and that the membrane (12) comprises several clamping openings (48) distributed around its circumference, arranged such that the clamping openings (48) are arranged complementarily to the clamping elements (44) of the damping device (17).Membrane (12) according to claim 8, characterized in that the membrane (12) comprises, in addition to the clamping openings (48), at least two, preferably more, tension or assembly openings (60) over half, preferably over a quarter, of its circumference, preferably on at least one, two or three sides. Membrane (12) according to claim 9, characterized in that the tension or assembly openings (60) are arranged centrally between the clamping openings (48). Membrane (12) according to any one of claims 9 to 10. characterized in that the pulling or mounting openings (60) are arranged in line with the clamping openings (48) or that the pulling or mounting openings (60) are arranged offset from the clamping openings (48) in the direction towards the edge of the membrane (12).

12. Membrane (12) according to one of claims 8 to 11, characterized in that the membrane (12) comprises at least one area (27) with a reflection-enhancing coating (27) or reflection-enhancing plating (27) on the side facing the opening area (10) of the upper part (17.2), preferably at at least one opening (11) of the opening area (10) associated with 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, which is passable through by a fibrous suspension having a flow direction (18), 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), upstream of a division of the fibrous suspension in the transverse direction (CD).

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

Images