Method and machine for producing a dry-laid fibrous web

Abstract

The invention relates to a machine (1) and to a corresponding method for producing a dry air-laid fibrous web (309). The machine (1) comprises: a) a low-water raw material preparation of cellulose-containing fibers (200), in particular fibrous material in the form of bales or sheets, in order to form individual fibers and / or fiber bundles (209); b) a dry-forming device (4) for dry-forming the individual fibers and / or fiber bundles (209) in an air stream in order to form a flat laid fibrous structure (300) on a forming belt (40); c) an application device (71) for applying a fluid, preferably water and / or a water-additive mixture, to the laid fibrous structure (300); d) a solidifying device (8) for solidifying the flat laid fibrous structure (300) by applying pressure and / or temperature, in particular in a press gap (81), preferably when the laid fibrous structure (300) is guided through the press gap (81) on a press belt (41); as well as an edge cutter (55), for separating the laid fibrous structure (300), using a compressed air jet (55a), into a transfer strip (301) and a waste part (302), wherein the transfer strip (301) is directed to a roller (12) and the waste part (302) is directed to a pulper (210).

Description

[0001] Method and machine for producing a dry-elasticated fiber web

[0002] The invention relates to a method for producing a fibrous web, preferably a tissue, paper or cardboard web or a nonwoven web, comprising the following steps: a) low-water raw material preparation of cellulose-containing fibers into individual fibers and / or fiber bundles; b) forming the individual fibers and / or fiber bundles in an air stream into a planar fiber layup on a forming belt by a dry forming process; c) application of a fluid, preferably water and / or a water-additive mixture, to the fiber layup; d) consolidation of the planar fiber layup by applying pressure and / or temperature in at least one consolidation device, in particular in a press gap, preferably wherein the fiber layup is guided through the press gap on a press belt.

[0003] Many fiber webs, especially paper, cardboard, or tissue, were and still are produced almost exclusively using wet processes on an industrial scale. To transfer the fiber web through the machine after a break or start-up, so-called end cutters are used. These cutters split the paper web lengthwise into a transfer strip and a waste section. Such end cutters often have a mechanical cutting edge or are designed as water jet trimmers, which separate the fiber web with a water jet. Since the fiber web undergoes several drying stages in the subsequent manufacturing process anyway, the water introduced into the fiber web during the cutting process is removed from the paper web.In the production of dehydrated fiber webs, the use of water is largely reduced; in particular, the introduction of water not directly involved in the fiber web production process must be avoided, making the use of water jet trimmers for cutting the fiber web disadvantageous. The use of mechanical cutting also has drawbacks, such as a narrow kerf, which carries the risk of the cut edges rejoining or excessive cutting edge wear.

[0004] For industrial-scale production, a high, continuous production speed or fiber web speed of 300 m / min or greater, in particular 400 m / min or greater, preferably 500 m / min or greater, particularly preferably 600 m / min or 800 m / min, and a width of the continuously produced fiber web of 0.5 m or greater, preferably 1 m or greater, in particular 2.7 m or greater to 7.2 m or less, or 10 m or less, is desired.

[0005] It is therefore an object of the present invention to provide a method and a machine for producing a dehydrated fibrous web, in particular a tissue web, with which the problems described above can be solved or at least reduced. In particular, it should be possible to reliably transfer a fiber layup through the machine for winding after a break or machine start-up during the production of a dehydrated fibrous web, especially without introducing additional water into the manufacturing process.

[0006] The problem described above is solved by the features of the independent claims. The dependent claims relate to advantageous embodiments of the present invention.

[0007] In particular, the problem is solved by the manufacturing process described at the outset, which is characterized in particular by the fact that, for the transfer of the fiber fabric to the winding process, the fiber fabric is separated into a transfer tape and a waste part by means of at least one air pressure jet, wherein the transfer tape is led to the winding process and the waste part to a pulper.

[0008] The inventors have recognized that the fiber layup of a fiber web, particularly one that has been dried, can be separated using an air jet, thereby preventing water from being introduced into the fiber layup by the separating device. Accordingly, a method for producing a fiber web is proposed in which the fiber layup is separated by means of at least one air jet in the machine direction into a, in particular, comparatively narrow transfer strip and a wider waste section. This known separation of the fiber layup allows a narrow, and therefore more manageable, transfer strip to be conveyed through the entire machine until it is wound up. The typically much wider waste section can then be fed separately from the transfer strip to a pulper, in particular to allow the fibers of the waste section to be reintroduced into the manufacturing process.The separation can be achieved by one or more compressed air jets, depending in particular on the strength of the fiber fabric, the desired cutting pattern, and the design of the at least one compressed air nozzle and thus also of the compressed air jet(s). Once the transfer belt has reached the winding unit, the separation of the fiber fabric can be completed, in particular by widening the transfer belt to the width of the fiber fabric and thus guiding the fiber fabric through the machine to the winding unit across the entire machine width.

[0009] In one embodiment of the method, the fiber fabric is separated as long as it exhibits a lower strength than the manufactured fiber web. The strength during the separation process is less than 80% of the strength of the manufactured fiber web, particularly less than 50%, and especially less than 25%, and preferably less than 10%, and more preferably less than 5%, of the strength of the manufactured fiber web. The strength of the fiber fabric increases, in particular, with the number or density of bonding points between the fibers through mechanical strengthening and through the application of a fluid, especially with the number or density of hydrogen bonds formed. The lower the strength of the fiber fabric during separation by the at least one air jet, the easier it is to separate by at least one air jet.In general, the strength of the fiber fabric increases with the progression of processing during the manufacturing process.

[0010] In one embodiment of the method, the application of a fluid, in particular a water-additive mixture, to the fiber fabric is suspended during the transfer of the transfer tape to the winding stage. During this transfer, the respective (guide) components of the machine, in particular tapes, coverings, or rollers, are not covered with the fiber fabric in all areas, especially in the area of ​​the cutting cut or after the removal of the waste material in a partial area of ​​the machine width. Accordingly, during the transfer of the transfer tape, fluid would be applied to the (guide) components of the machine, which, particularly with a water-additive mixture, would lead to contamination of these components.An applied fluid could adhere to the relevant equipment and also be transferred to a fiber fabric subsequently guided over it, resulting in contamination of the fiber fabric or, in the case of water application, the undesirable introduction of water into the fiber fabric. Furthermore, additives already applied to the waste component have a detrimental effect on the recycling and reuse of the fibers from the waste tape as recycled material in raw material processing. In one embodiment of the method, the application of a fluid, preferably water, is maintained during the transfer of the transfer tape to the winding stage. The fluid creates bonds, particularly in the form of hydrogen bonds, between the fibers of the fiber fabric, thereby stabilizing the transfer tape.Any risk of tearing of the fiber lay-up that may arise during the transfer process can be reduced or eliminated by applying a fluid, preferably water, through the application device after separation.

[0011] In one embodiment of the process, the width of the separation cut is greater than the fiber length of the fibers in the fiber layup. This prevents fibers from the fiber layup from crossing the separation cut and forming bonds on both sides of the cut. This could lead to disruptions in the process flow, particularly during the removal of the waste material, especially into a pulper.

[0012] In one embodiment of the method, the fiber fabric is separated into a transfer strip and a waste portion by means of at least one compressed air jet upstream of a pre-consolidation device, a press gap, or a further press gap. During the process, the fiber fabric exhibits lower strength downstream of a pre-consolidation device, a press gap, or a further press gap than downstream of these devices, which promote the formation of bond points within the fiber fabric. Since separating the fiber fabric with at least one compressed air jet becomes more difficult with increasing fiber fabric strength, separating the fiber fabric upstream of further consolidation is advantageous.Additionally, the consolidation of the fiber layup also consolidates the cut edges formed during the separation process, thereby improving the stability and handling of the transfer strip immediately after its formation and thus facilitating its transfer through the machine. In one embodiment of the process, the fiber layup is fed to a pulper in a web width before the separation process, with the pre-consolidation device closed and at least one press gap open, in particular the press gap and / or the further press gap open. This process phase can be carried out at the beginning of the transfer of the fiber layup to the reel, especially after production has started or after a production disruption, and before the separation process of the fiber layup into a transfer strip and a waste part begins.The pre-consolidation unit is closed to give the fiber layup a basic strength, which in particular simplifies its feeding to the pulper. At least one press gap is open, specifically the press gap and / or the subsequent press gap. This ensures a trouble-free process start-up and / or execution, especially when the fiber layup is initially fed through the press gap and / or the subsequent press gap.

[0013] In one embodiment of the process, as soon as the fiber layup is discharged into a pulper located behind a press gap and / or a further press gap in the machine direction (MD), this press gap and / or this further press gap are closed sequentially, particularly in the machine direction (MD). In this embodiment, it is provided, particularly to achieve a trouble-free process flow, that the fiber layup is initially guided to the pulper through open press gaps, preferably in the form of pressing elements such as at least two rollers, and that the consolidation devices or press gaps are only closed once the fiber layup has reached the designated pulper during its passage through the machine. Independently of this, pre-consolidation of the fiber layup can take place in any process phase, and a corresponding pre-consolidation device for the fiber layup can be closed independently of the discharge of the fiber layup into the pulper.In one embodiment of the method, when the fiber layup is discharged into a pulper located in the machine direction (MD) upstream of the further press gap, the further press gap is only closed once the transfer belt has passed through it. In this embodiment, the further press gap is first traversed by the transfer belt, the beginning of which is to be guided through the further press gap without obstruction. For this purpose, it is advantageous if the further press gap is initially open. As soon as the transfer belt has passed through the further press gap and / or reached the winding unit, these can be closed to effect consolidation of the transfer belt and subsequently of the fiber layup across the machine width.

[0014] In one embodiment of the method, the separation process of the fiber layup into a transfer strip and a waste section is carried out when the pre-consolidation device and a press gap and / or a further press gap are closed. Because the transfer strip is guided through a closed pre-consolidation device and the closed press gap and / or the closed further press gap in this embodiment, the transfer strip acquires increased strength, thus enabling more reliable transfer of the transfer strip to the winding stage.

[0015] In one embodiment of the method, the transfer belt is moved across a gap through which the waste material is discharged into the pulper. As the transfer belt moves across this gap, it continues to be guided through the machine, while the waste material is discharged into the pulper. To guide the beginning of the transfer belt across the gap, transfer energy is applied to it, for example. This energy forms the beginning of the transfer belt, which then runs continuously into the pulper, and essentially moves it across the gap simultaneously. Alternatively, a guide structure can be provided that guides the beginning of the transfer belt across the gap, so that the transfer belt reaches the subsequent guide for the fiber layup of the machine.

[0016] In one embodiment of the method, the transfer tape is separated from the fiber mat by the distance before transfer. This separation, which can be achieved in particular by means of a cutting edge or also by means of an air jet, allows the transfer tape to be advanced independently of the waste part.

[0017] In one embodiment of the method, after the transfer belt has been transferred to the winding unit, at least one jet of compressed air is moved away from the transfer belt in the transverse direction (CD) of the machine, separating the waste portion from the fiber web. This moves the separation point of the transfer belt and the waste portion to the edge of the fiber web furthest from the transfer belt, thereby increasing the width of the transfer belt to the full width of the fiber web. This step is therefore also called "widening." Once the width of the fiber web is reached, the waste portion is completely separated from the fiber web and subsequently fed into the pulper. A uniform fiber web is then fed to the winding unit, resulting in a single, web-width fiber web.

[0018] In one embodiment of the process, the produced fibrous web is, in particular, a one-, two-, three-, four- or more-layered tissue web with a basis weight of 5 g / m². 2 up to 75 g / m² 2 , especially of 15 g / m² 2 up to 60 g / m² 2 , preferably of 25 g / m² 2 up to 45 g / m² 2 , particularly preferably 28 g / m² 2up to 42 g / m². The proposed method is particularly suitable for producing such fibrous webs. Furthermore, the problem is solved by a machine for producing a fibrous web, preferably a tissue, paper, or cardboard web or a nonwoven web, wherein the machine comprises: a) a raw material preparation plant for the low-water processing of cellulose-containing fibers into individual fibers and / or fiber bundles; b) a dry forming device for the dry forming of the individual fibers and / or fiber bundles in an air stream into a planar fiber layup on a forming belt; c) an application device for applying a fluid, in particular water and / or a water-additive mixture, to the fiber layup; d) a consolidation device for consolidating the planar fiber layup by applying pressure and / or temperature, in particular in a press gap, preferably when the fiber layup is guided through the press gap on a press belt.

[0019] The machine further features a tip cutter for separating the fiber layup by means of an air pressure jet into a transfer tape and a waste part, wherein the transfer tape can be guided to a reel and the waste part to a pulper.

[0020] The machine is specifically designed to carry out the method described above. Accordingly, the advantageous embodiments previously described for the method according to the invention also apply analogously to the machine according to the invention. In particular, the machine has a cutting blade with which the fiber layup of the preferably dried fiber web can be separated by means of an air jet, thereby preventing water from being introduced into the fiber layup by the cutting device.

[0021] In one embodiment of the machine, the point cutter has at least one compressed air nozzle that is movable in the transverse direction of the machine. The compressed air nozzle is configured to generate a jet of compressed air from the supplied air, which causes the fiber fabric to separate. In particular, the compressed air jet is designed to create a separation cut in the fiber fabric whose width is greater than the fiber length of the fibers in the fiber fabric. This prevents fibers from crossing the separation cut and forming bonds on both sides of the cut. The point cutter can also have two or more compressed air nozzles to achieve the formation of a suitable separation cut.Thus, when using at least two compressed air nozzles, a second compressed air jet from a second nozzle can widen the cut following a separation cut made by the compressed air jet from a first nozzle. For higher basis weights or strengths of the fiber fabric, at least two compressed air nozzles may be necessary, for example, to ensure adequate separation of the transfer tape and the waste tape.

[0022] In particular, the tip cutter may also have at least one extraction device which picks up fibers released during the cutting process and removes them from the cutting point.

[0023] In one embodiment, the end cutter may also have at least two compressed air nozzles spaced apart in the machine's transverse direction (CD = Cross-Direction) to produce two adjacent cutting cuts. This creates a waste tape between the cutting cuts, which can be removed from the fiber layup by means of a removal device, particularly a suction device. This ensures reliable separation of the transfer tape and the waste tape, preventing potential malfunctions that could result from an unreliable separation of the two.

[0024] In one embodiment of the machine, at least one compressed air nozzle is arranged at an angle in the machine direction (MD = Machine-Direction), with the compressed air jet directed forward in the machine direction and the angle of inclination relative to the vertical being between 10° and 45°. By inclining the compressed air jet of the nozzle in the machine direction, an improved separation effect of the fiber layup can be achieved. Depending on the fiber length and the basis weight of the fiber layup, the desired separation effect of the compressed air nozzle can be adjusted—in addition to the nozzle shape and the pressure of the compressed air used—by adjusting the inclination of the compressed air nozzle and thus of the compressed air jet.

[0025] In the context of the present invention, the term "low-water" raw material processing also includes processing the raw material entirely without the targeted addition of water and / or other liquids. "Low-water" raw material processing is understood to mean that the amount of water already contained in the provided, air-dried raw material is sufficient for the processing process, and the processing can be carried out without any further addition of water or moisture. The water content of the air-dried raw material is typically between 1% and 30%, particularly between 1% and 20%, and especially between 1% and 10%, based on the mass of the raw material.

[0026] Alternatively, in a "low-water" processing method, it may also be provided that a small amount of water or moisture is added to the raw material during the processing, so that the water content of the raw material or the chips and / or the individual fibers does not exceed a maximum limit of 30%, in particular 20%, in particular 10%, based on the mass of the raw material, the chips or the individual fibers in the individual processing steps.

[0027] It must be taken into account that the raw material can absorb water or moisture from its environment during storage for at least several hours, the maximum amount of which depends on the raw material, the storage conditions, and the environmental conditions. The invention expressly extends to embodiments that are not defined by combinations of features from explicit cross-references to the claims, meaning that the disclosed features of the invention can be combined arbitrarily, insofar as this is technically feasible.

[0028] To differentiate between the manufactured fiber webs, for example a tissue, paper or cardboard web, especially in a basis weight range of 5 g / m² 2 up to 600 g / m² 2 , on the one hand, or a non-woven fabric (in English "non-woven") on the other hand, the following distinction is made, which is based on fiber length, density and fiber bonding type:

[0029] A fibrous web with predominantly medium fiber lengths, shorter than the fiber lengths of nonwoven webs, of less than or equal to 5 mm, in particular less than or equal to 4 mm, in particular less than or equal to 3 mm, predominantly bonded by hydrogen bonds and with a bulk density of greater than or equal to 0.4 g / cm³, is placed under a tissue, paper or cardboard web. 3 Understood. The fibers used in a tissue, paper or cardboard web are additionally characterized by having a slenderness ratio (fiber length to fiber diameter) of less than or equal to 200, in particular less than or equal to 150, in particular less than or equal to 100.

[0030] A nonwoven web, which also consists primarily of fibers, is defined—as a key distinction from tissue, paper, or cardboard webs—by having a fiber content of at least 30% consisting of very long fibers with an average fiber length of more than 5 mm, or continuous fibers, which determine the nonwoven characteristics. Furthermore, a fiber-to-diameter ratio of greater than or equal to 300 is targeted for a nonwoven web. The remaining fiber content of a nonwoven web can be of a different composition, and the bulk density should be below 0.40 g / cm³. 3 The present invention requires that the fiber web be classified as a nonwoven fabric. Furthermore, the manufactured fiber web is free of artificial fibers as a raw material, for example, binding fibers such as bicomponent fibers, melt fibers, and other fibers available on the market that are synthetically or industrially produced.

[0031] The dry-formed fiber web thus consists solely of natural fibers from plant, animal, or mineral sources as raw material, with cellulose-containing fibers, i.e., from plant sources, being used preferentially. This allows a basic strength to be created through hydrogen bonds between the cellulose-containing fibers when water is applied.

[0032] Furthermore, when using exclusively cellulose-based fibers as raw material, a specific, preferably small, proportion of chemical binders in the form of a water-additive mixture can be applied to the fiber web to adjust the quality factors of the manufactured fiber web, such as strength, feel, and appearance. These water-additive mixtures can contain a certain proportion of synthetically or industrially produced components, such as polymers, in dissolved form, which are present in the final manufactured fiber web in a cured form.

[0033] Furthermore, the dry-formed fiber web is produced free from complex consolidation methods such as needling or water jet needling, which are usually used in the production of nonwoven webs.

[0034] Further features and advantages of the invention will become apparent from the following description of a preferred embodiment with reference to the drawing.

[0035] Exemplary embodiments of the invention are explained below with reference to the following figures. Fig. 1 shows a schematic representation of the structure of an exemplary machine 1 for producing a fibrous web 309;

[0036] Fig. 2a shows a section of an exemplary machine 1 for producing a fibrous web 309 in the area of ​​the end cutter 55 and the discharge of the waste part 302 into a pulper 210 in a top view; and

[0037] Fig. 2b shows a side view of the exemplary machine 1 for the production of a fiber web 309 from Fig. 2a.

[0038] To clarify the individual directions, a higher-level Cartesian coordinate system is used in the figures. The x-direction corresponds to a longitudinal extent, also known as the machine direction (MD). The y-direction corresponds to a direction orthogonal to the machine direction (MD) and is also known as the cross-direction (CD). The z-direction corresponds to the vertical direction.

[0039] Figure 1 and Figures 2a, 2b show, by means of a schematic representation, a possible embodiment of the manufacturing process according to the invention or of the construction of the machine 1 according to the invention, which can have a raw material preparation plant 2 and a fiber web plant 3.

[0040] In the upper left of Fig. 1, a possible embodiment of a low-water processing plant or a low-water raw material processing plant 2 is shown schematically, in which individual fibers and / or fiber bundles, for example from fiber-containing recycled material and / or from virgin fiber pulp, particularly as bales, can be produced by comminution devices and / or fiber defatting devices. After successful comminution or defatting, the individual fibers and / or fiber bundles can be transported in an air stream. The air / fiber mixture can be fed via one or more distribution channels to at least one dry forming device 4 of a fiber web plant 3 for the production of a dry-formed fiber web 309.The two manufacturing processes of the low-water raw material preparation 2 and the fiber web plant 3 can be coupled for the production of high-quality fiber webs 309, whereby both can be coordinated or controlled and / or regulated via a higher-level control and / or regulating device 60.

[0041] Optionally, conditioning can be performed after cleaning the raw material. During conditioning, a small amount of moisture can be added to the cleaned raw material, for example, to minimize or prevent dust formation and / or electrostatic charging. Additives can also be added during conditioning. Recycled material from other fiber web production plants or waste paper can be added to the raw material. Furthermore, machine rejects or scrap from fiber web plant 3 can also be added. These rejects could be, for example, waste parts 302 or edge trimming 50 or edge extraction 50, in which fibers from a fiber layup 300 are extracted from the edge after at least one dry forming device 4.Furthermore, individual fibers and / or fiber bundles filtered from the ambient air that have not been deposited can also be added back in as rejects. It is advantageous if the recycled material and / or rejects contain no additives and thus meet the specified quality requirements without further processing steps.

[0042] In the embodiment shown in Figure 1, only one exemplary dry forming device 4 is depicted. The fiber web system 3 can also have several dry forming devices, in particular to produce superimposed layers of the finished fiber web 309. The individual fibers and / or fiber bundles 209 processed from the raw material can be fed to at least one dry forming device 4 of the fiber web system 3 and, in particular, distributed as uniformly as possible transversely to the machine direction MD or in the machine transverse direction CD of the fiber web system 3.

[0043] Following at least one dry forming device 4, two application devices 7 can be provided, which can apply a fluid, in particular water or a water-additive mixture, to the fiber fabric 300 or the consolidated fiber fabric 305. The at least two application devices 7 can be configured as a first application device 71 and at least one further application device 72, 73. The application of a fluid to the fiber fabric 300 by at least one, in particular all, application devices 71, 72, 73 can be suspended during the transfer of the transfer belt 301 to the winding unit 12, in particular to prevent contamination of machine components by water-additive mixtures or to prevent the fiber fabric of the waste part 302 from being burdened by additives or moisture for subsequent reuse.

[0044] Furthermore, at least one consolidation device 8 can be provided after the at least one dry forming device 4, which can consolidate the fiber fabric 300. In the embodiment shown in Fig. 1, three consolidation devices 8 are arranged by way of example. In particular, at least one consolidation device 8 can be designed such that, in addition to consolidating the fiber fabric, it can also structure and / or heat it. The structuring by the consolidation device 8 can be used in particular for the production of a tissue web with low- and high-pressure zones, especially a tissue web with a basis weight of 28 g / m². 2 up to 42g / m² 2 , be important.

[0045] Furthermore, it can be provided that, in the case of several consolidation devices, for example a pre-consolidation device 83, a press gap 81 and / or a further press gap 82, the applied pressures or line loads for consolidation of the fiber fabric by the pre-consolidation device 81 are lower than the line loads in the press gap 81. Furthermore, the line load in the press gap 81 can be less than or equal to the line load in the further press gap 82.

[0046] Furthermore, the consolidation device 8 can be configured as at least one press gap with at least two pressing elements. It is also possible for three or four pressing elements to be provided in one press gap. For example, the press gap 81 is configured with three pressing elements, wherein the press gap is formed by a press belt 42 and two press rollers. For example, the further press gap 82 is configured with two pressing elements as two press rollers.

[0047] Furthermore, a multi-press roller arrangement can be provided, whereby one, two or three press gaps can be formed in combination with the same press rollers.

[0048] To complete the continuously produced fiber web 309, a web-width winding unit 12 can be arranged at the end of the fiber web system 3.

[0049] The fiber web system 3 can have at least one drying device 10. It is advantageous if the at least one drying device 10 is arranged downstream of the application devices 7 in order to dry the fiber web 309, onto which a fluid, in particular in a metered quantity, has been applied. In particular, the at least one drying device 10 can be arranged upstream of the winding 12 of the finished fiber web 309.

[0050] The dry forming step in the at least one dry forming device 4 can be controlled and / or regulated by at least one control and / or regulating means, wherein the individual fibers and / or fiber bundles 209 in the dry forming device 4 can be laid down, in particular partially, by weight force onto a circulating, in particular permeable, forming belt 40 and can form a fiber fabric 300 that is in particular still substantially unconsolidated. Furthermore, the dry forming device 4 can include a suction device 30 which can assist in laying down the individual fibers 209 on the permeable forming belt 40, and in particular can also influence this process as a control and / or regulating means.

[0051] In particular, the fiber layup 300 can be measured with respect to its mass distribution or basis weight distribution by at least one enclosed measuring device 61, in particular a mass measuring device extending in the transverse direction CD of the machine. The measurement signal can act as a control variable, in particular via the higher-level control and / or regulating device 60, on the feed of the individual fibers from the raw material preparation plant 2 and / or on the suction device 30.

[0052] The air 39 extracted by the suction device 30 may contain a certain quantity of individual fibers 209. Therefore, it is advantageous if a large proportion, in particular up to 95%, of the air volume extracted by the respective suction device 30 can be returned directly to the dry forming device 4 in a recirculation circuit. This makes it possible to break down the continuously added individual fibers 209 even better in order to achieve good formation on the forming belt 40, while the extracted individual fibers can be immediately fed back into the corresponding production step.

[0053] As shown in Fig. 1, the fiber fabric 300 can pass through a pre-solidification device 83 before the first application device 71, in which the still unsolidified fiber fabric 300 can receive a first, full-surface pre-solidification or pre-compacting over the entire machine transverse direction CD.

[0054] In one embodiment, a first application device 71 may apply a fluid in the form of water, in particular free of, preferably chemical, additives, to the fiber fabric 300. Furthermore, the first application device 71 may be located downstream of a pre-hardening device 83.

[0055] The first application device 71 can preferably apply a quantity of water of 1 to 20% based on the mass or basis weight of the fiber fabric 300.

[0056] The first application device 71 can be activated before or after the transfer of the transfer belt 301. If activated before the transfer, the transfer belt 301 and the cutting edge 310 can additionally form bonds in the form of hydrogen bonds, thus exhibiting increased strength. Contamination of the support elements, in particular the forming belt 40, the pressing belt 41, the transfer belts 102 and 103, and / or the drying belt 42, cannot occur with a pure water application.

[0057] Immediately before being wound up 12, the fiber web 309 can be passed through a drying device 10. The properties of the fiber web 309 with regard to its thickness, its feel characteristics and / or its absorption capacity can be advantageously maintained by means of, for example, a contactless drying device 10.

[0058] The application devices 71, 72, 73 can be designed such that the fiber fabric 300 can be wetted over its entire surface with the fluid. In the first, second, and / or third application device 71, 72, 73, a vacuum box 31 can be arranged on the side of the fiber fabric 300 opposite the side to be wetted. This vacuum box can draw ambient air through the fiber fabric 300 and through a permeable support element supporting the fiber fabric 300, preferably a pressure belt 41 and / or a transfer belt 103 and / or a drying screen 42, by means of a negative pressure applied, particularly during application. Reference numeral 22 indicates the respective direction of travel of the pressure belt 41 and other coverings in Fig. 1. Optionally, at least one moisture measuring device 63 and / or a measuring device for monitoring the fluid application can be provided.The at least one moisture measuring device 63 can be arranged in such a way that it can measure before and / or after the heating device 10.

[0059] The connecting belt 102 can guide the fiber fabric 300 from the press belt 41 to just before a further press gap 82, through which the fiber fabric 300 can then be guided unsupported. In the further press gap 82, the fiber fabric 300 can be further consolidated by pressure and / or temperature before it can be guided as a further consolidated fiber fabric 305 to the dryer device 10. The further press gap 82, like the press gap 81, can be provided by the nip between two rollers. However, because the fiber fabric 300 can be guided unsupported through the further press gap 82, unlike at the previous press gap 81, no consideration needs to be given to the stability of a supporting fabric for the fiber fabric 300 at this point. This makes it possible to apply significantly higher pressures to the fiber fabric 300 in the wider press gap 82 than is the case in the press gap 81.The higher pressures allow for significantly greater strength in the finished fiber web 309. The rollers should therefore be designed to be correspondingly robust. For example, the rollers can be made primarily of steel. At least one of the two rollers forming the further press gap 82 between them can also be designed to provide the fiber fabric 300 with a multitude of high-pressure and low-pressure zones.

[0060] The connecting belt 102 is specifically designed to guide the fiber fabric 300 as close as possible to the further press gap 82, in order to keep the free tension, i.e., the distance that the fiber fabric 300 must travel unsupported between the connecting belt 102 and the further press gap 82, as short as possible. For this purpose, a final connecting belt deflection roller, i.e., the deflection roller at the end of the conveying section of the connecting belt 102, can have a relatively small diameter, and the connecting belt 102 itself can be designed to be sufficiently flexible to follow the correspondingly strong surface curvature of the final connecting belt deflection roller.

[0061] After exiting the further press gap 82, the further consolidated fiber fabric 305 can be picked up by a transfer belt 103, which can transfer the further consolidated fiber fabric 305 onto the drying screen 42. For similar reasons as before, the transfer belt 103 can be designed similarly to or identically with the connecting belt 102.

[0062] In order to be able to process the fiber fabric 300 as smoothly as possible even at industrial production speeds, it is advantageous if at least one of the two rollers forming the further press gap 82, and / or the connecting belt 102 and / or the transfer belt 103 are adjustable in their position so that the angle at which the fiber fabric 300 enters the further press gap 82, and / or the angle at which the further consolidated fiber fabric 305 leaves the further press gap 82, can be specifically adjusted.

[0063] After the further consolidated fiber fabric 305 has been transferred to the drying screen 42, fluid can again be applied to the side of the further consolidated fiber fabric 305 facing away from the drying screen 42 by the third application device 73. Thus, the further consolidated fiber fabric 305 can be moistened from both sides by the second application device 72 and / or the third application device 73 before it is dried in the drying device 10 and subsequently wound onto the winding unit 12.

[0064] The machine 1, in particular the fiber web system 3, can further comprise a cutting edge 55 for separating the fiber layup 300 by means of an air jet 56a into a transfer strip 301 and a waste section 302. The cutting edge 55 and the separation of the fiber layup 300 by means of the cutting edge 55 into a transfer strip 301 and a waste section 302 are shown and described in more detail in Fig. 2. The cutting edge 55 can be positioned at several locations in the fiber web system 3. In Fig. 1, three cutting edge 55s are shown at three suitable positions, at which the separation of the fiber layup 300 can take place before a pre-consolidation device 83, before a press gap 81, or before a further press gap 82, whereby usually only one cutting edge 55 is used.

[0065] Before the fiber layup 300 is separated into a transfer strip 301 and a waste section 302 by an air jet 56a generated by the end cutter 55 or by a nozzle 56 encompassed by it, the fiber layup 300 as a whole can be fed to a pulper 210. A pulper 210, which or its feed is shown schematically in Fig. 1, can be part of the raw material preparation and serve to process fibers, especially those recycled from the process, and in particular also fibers from the waste section 302, in order to (re)introduce them into the manufacturing process.

[0066] By conveying, in particular, portions of the fiber fabric 300 into a pulper 210, this material, or the conveyed portion, can be removed from the manufacturing process. In the illustration of machine 1 in Fig. 1, three pulpers 210 or return devices to such a pulper are shown by way of example at positions suitable for the proposed method. In the proposed method, it can be advantageous if, before the separation process, when conveying the fiber fabric 300 to a pulper 210, the pre-consolidation device 83 is closed and at least one press gap 81, 82 is open, in particular one press gap 81 and / or a further press gap 82. As soon as the fiber fabric 300 is conveyed into a pulper 210 arranged behind the press gap 81 and / or the further press gap 82 in the machine direction MD, this press gap 81 and / or this further press gap 82 can be closed successively, particularly in the machine direction MD.If the fiber layup 300 is discharged into a pulper 210 arranged in the machine direction MD in front of the further press gap 82, it is advantageous to close the further press gap 82 only when the transfer belt 301 has already been led to the winding 12.

[0067] Fig. 2a shows a section of an exemplary machine 1 for producing a fiber web 309 in the area of ​​the end cutter 55 and the discharge of the waste portion 302 to a pulper 210 in a top view, and Fig. 2b shows the section from Fig. 2a in a side view. In the process, the situation shown in Fig. 2a corresponds to the point in time shortly after the transfer ribbon 301 has reached the reel 12 (cf. Fig. 1). Above the fiber web 300, an end cutter 55 can be arranged, which can separate the fiber web 300 by means of an air jet 56a into a transfer ribbon 301 and a waste portion 302, which can be guided separately from each other further parallel in the machine direction MD through the machine 1.After the transfer tape 301 has been transferred to the winding unit 12, the end cutter 55 can move in the machine transverse direction CD such that the width of the transfer tape 301 increases and the width of the waste section 302 decreases until the waste section 302 is separated from the transfer tape 301, and the fiber layup 300 can be guided through the machine 1 in its entirety. Due to the movement of the fiber layup in the machine direction MD, the transfer tape can widen at an angle resulting from the movement speed of the end cutter 55 in the CD direction and the movement speed of the fiber layup 300 in the machine direction MD, so that the width of the transfer tape 301 that can be guided to the winding unit does not increase abruptly, but gradually, thereby improving process stability.The end cutter 55 can have at least one compressed air nozzle 56, which can serve to generate a compressed air jet 56a suitable for separating the fiber fabric 300, particularly at a position of the machine 1 where the fiber fabric 300 has a lower tensile strength than the produced fiber web 309. The resulting separation cut can have a width that is particularly greater than the fiber length of the fibers of the fiber fabric 300. Figure 2b also shows the inclination of a compressed air nozzle 56 of the end cutter 55. As shown, the compressed air nozzle 56 can be arranged inclined in the machine direction MD such that the compressed air jet 56a is directed forward in the machine direction MD relative to the vertical z by an angle of inclination α, which can be in the range of 10° to 45°.

[0068] Figures 2a and 2b further illustrate that the transfer belt 301 can be moved across a gap 111, through which the waste part 302 can be discharged into a pulper 210. In this way, the waste part 302 can be returned to the raw material preparation and reused in the process. Furthermore, only the transfer belt 301 can be moved to the next section, through the further press gap 82, or to the reel 12. Due to the width and mass of the transfer belt 301, this can be simpler and more reliable than moving the entire fiber web 300, or the entire web width, to the reel 12 after a machine start or process disruption. For moving the transfer belt 301 across the gap 111, a device shown in Figure 2a can be used, for example.2b, an exemplary transfer device 110 is used, which can support the transfer belt 301 from above or below in the open area of ​​the gap 111 and guide it across this gap. Before the transfer belt 301, which runs continuously into the pulper 210, is transferred across the gap 111, a beginning of the transfer belt 301 can usually be formed by a separation in the CD direction, and the section of the transfer belt 301 running into the pulper 210 can be separated from the remaining section with a new belt beginning. For this purpose, the introduced transfer energy, for example in the form of an air jet or guide vanes, and / or a separation device 110a can be used. The new beginning of the transfer belt 301 can be transferred to the next section, for example through the further press gap 82 and / or to the winding unit 12, essentially simultaneously with its formation.The proposed method is described below in connection with the machine shown in the figures, using three exemplary process sequences. In a first process sequence, the web can initially be guided across its entire width to a pulper 210 located shortly before the winding unit 12, with the pre-consolidation device 83 closed and the press gap 81 and the further press gap 82 open. Subsequently, the at least one press gap 81 and then the further press gap 82 can be closed, and the separation process can begin, whereby the end cutter 55, in particular by means of an air jet 56a, can separate a transfer strip 301 from a waste part 302. These two parts of the fiber layup 300 can then be guided further through the machine 1, whereby the fiber layup 300, 305 can be transferred over possible distances 111 by means of a transfer device 110 (each).The waste material 302 can be discharged into a pulper 210 shortly before reaching the reel 12, and the transfer belt 301 can be guided to the reel 12. Once the transfer belt 301 has reached the reel 12, the end cutter 55 can move away from the transfer belt 301 in the CD direction, thereby "spreading out" the transfer belt 301 as described in Figure 2a. Any application of a fluid to the fiber web 300, 305 that may have been interrupted can be resumed after the transfer belt 301 has spread out, and the production of the fiber web 309 can thus enter a stable process.

[0069] In a second exemplary process sequence, the web can first be guided across its entire width to a pulper 210 arranged upstream of the further press gap 82, with the pre-consolidation device 83 being closed and the press gap 81 and the further press gap 82 being open. The at least one press gap 81 can then close, and the separation process can begin, in that the end cutter 55, in particular by means of an air jet 56a, can separate a transfer strip 301 from a waste part 302. These two parts of the fiber layup 300 can then be guided further through the machine 1, with the fiber layup 300, 305 being transferred over possible distances 111 by means of a transfer device 110. The waste part 302 can be discharged into a pulper 210 shortly after reaching the further press gap 82, and the transfer belt 301 can be guided further to the reel 12, particularly through the further press gap 82.Once the transfer tape 301 has reached the coil 12, the further press gap 82 can close and the tip cutter 55 can move away from the transfer tape 301 in the CD direction, thereby widening the transfer tape 301. Any interrupted application of a fluid to the fiber web 300, 305 can then be resumed, and the production of the fiber web 309 can thus enter a stable process.

[0070] In a third exemplary process sequence, the web can first be guided across its entire width to a pulper 210 located downstream of the further press gap 82, with the pre-consolidation device 83 closed, while the press gap 81 and the further press gap 82 can be open. Subsequently, the press gap 81 and the further press gap 82 can be closed sequentially, and the separation process can begin, whereby the end cutter 55, in particular by means of an air jet 56a, can separate a transfer strip 301 from a waste part 302. These two parts of the fiber layup 300 can then be guided further through the machine 1, whereby the fiber layup 300, 305 can be transferred over possible distances 111 by means of a transfer device 110. The waste part 302 can be discharged into a pulper 210 immediately after passing through the further press gap 82 and the transfer belt 301 can be guided further to the reel 12.Once the transfer tape 301 has reached the winding 12, the end cutter 55 can move away from the transfer tape 301 in the CD direction, thereby widening the transfer tape 301. Any interrupted application of a fluid to the fiber web 300, 305 can then be resumed, and the production of the fiber web 309 can thus enter a stable process. (See list of reference symbols.)

[0071] 1 machine

[0072] 2 Raw material processing plant

[0073] 3 Fiber web plant

[0074] 4 T dry forming device

[0075] 7 Application device

[0076] 8 Solidification device

[0077] 10 T dryer device

[0078] 12 Roll-up

[0079] 22 Direction of travel

[0080] 30 Suction device of the dry forming device

[0081] 31 Vacuum Box - Application Device

[0082] 32 vacuum boxes

[0083] 39 extracted air

[0084] 40 support element, forming belt

[0085] 41 Support element, press band

[0086] 42 Support element, drying sieve

[0087] 50 Edge trimming (edge ​​suction)

[0088] 55 top tailors

[0089] 56 Compressed air nozzle

[0090] 56a Air jet

[0091] 60 Control and / or regulating device

[0092] 61 Measuring device

[0093] 63 Moisture measuring device

[0094] 71 first application device

[0095] 72 second application device 73 third application device

[0096] 81 Press gap

[0097] 82 more press gap

[0098] 83 Pre-solidification device

[0099] 102 Connecting strap

[0100] 103 Transfer tape

[0101] 110 Transfer device

[0102] 110a Disconnect device

[0103] 111 distance

[0104] 209 single fibers and / or fiber bundles

[0105] 210 Pulper

[0106] 300 fiber layups after dry forming device

[0107] 301 transfer straps

[0108] 302 Waste section

[0109] 305 reinforced fiber fabric

[0110] 309 Fibre web

[0111] MD Machine direction

[0112] CD machine transverse direction z vertical direction

Claims

- 29 - 1. A method for producing a fibrous web (309), preferably a tissue, paper or board web or a nonwoven web, comprising the following steps: a) low-water raw material preparation of cellulose-containing fibers (200), in particular bale- and / or sheet-shaped fiber material, into individual fibers and / or fiber bundles (209); b) forming the individual fibers and / or fiber bundles (209) in an air stream into a planar fiber layup (300) on a forming belt (40) by a dry forming process; c) application of a fluid, preferably water and / or a water-additive mixture, to the fiber layup (300); d) Consolidating the planar fiber fabric (300) by applying pressure and / or temperature in at least one consolidation device (8), in particular in a press gap (81), preferably wherein the fiber fabric (300) is guided through the press gap (81) on a press belt (41);characterized in that, for the purpose of transferring the fiber layup (300) to a reel (12), the fiber layup (300) is separated into a transfer ribbon (301) and a waste part (302) by means of at least one air pressure jet (56a), wherein the transfer ribbon (301) is guided to the reel (12) and the waste part (302) to a pulper (210).

2. Method according to claim 1, characterized in that the fiber fabric (300) is separated while it has a lower strength than the produced fiber web (309), wherein the strength during the separation process is less than 80%, in particular less than 50%, in particular less than 25%, preferably less than 10%, preferably less than 5%, of the strength of the produced fiber web (309). - 30 - 3. Method according to at least one of the preceding claims, characterized in that the application of a fluid to the fiber fabric (300) is suspended during the transfer of the transfer tape (301) to the winding (12).

4. Method according to at least one of the preceding claims, characterized in that the width of the separation cut is greater than the, in particular average, preferably 2 times the average, fiber length of the fibers of the fiber fabric (300).

5. Method according to at least one of the preceding claims, characterized in that the separation of the fiber layup (300) by means of at least one air pressure jet (56a) into a transfer strip (301 ) and a waste part (302) takes place before a pre-solidification device (83) or before a press gap (81 ) or before a further press gap (82).

6. Method according to at least one of the preceding claims, characterized in that the fiber layup (300) is guided in web width to a pulper (210) before the separation process, wherein a pre-consolidation device (83) is closed and at least one press gap (81, 82) is open, in particular the press gap (81) and / or the further press gap (82) are open.

7. Method according to at least one of the preceding claims, characterized in that as soon as the fiber layup (300) is discharged into a pulper (210) arranged in the machine direction (MD) behind a press gap (81 ) and / or a further press gap (82), this press gap (81 ) and / or this further press gap (82) are closed successively, particularly in the machine direction (MD).

8. Method according to at least one of the preceding claims, characterized in that the separation process is carried out when a pre-solidification device (83) and a press gap (81) and / or a further press gap (82) are closed.

9. Method according to at least one of the preceding claims, characterized in that when the fiber layup (300) is discharged into a pulper (210) arranged in the machine direction (MD) in front of the further press gap (82), the further press gap (82) is only closed once the transfer belt (301) has been guided through the further press gap (82).

10. Method according to at least one of the preceding claims, characterized in that the transfer belt (301 ) is transferred over a distance (111 ) through which the waste part (302) is discharged into the pulper (210).

11. Method according to at least one of the preceding claims, characterized in that after the transfer tape (301) has been transferred to the winding (12), the at least one air pressure jet (56a) is moved in the machine transverse direction (CD) such that the waste part (302) is separated from the fiber fabric (300).

12. Machine (1) for producing a fibrous web (309), preferably a tissue, paper or cardboard web or a nonwoven web, comprising: a) a raw material preparation plant (2) for the low-water processing of cellulose-containing fibers (200) into individual fibers and / or fiber bundles (209); b) a dry forming device (4) for the dry forming of the individual fibers and / or fiber bundles (209) in an air stream into a planar fiber fabric (300) on a forming belt (40); c) an application device (71) for applying a fluid, in particular water and / or a water-additive mixture, to the fiber fabric (300); d) a consolidation device (8) for consolidating the planar fiber fabric (300) by applying pressure and / or temperature, in particular in a press gap (81), preferably when the fiber fabric (300) is guided through the press gap (81) on a press belt (41); characterized by a tip cutter (55) for separating the fiber fabric (300) by means of an air pressure jet (56a) into a transfer belt (301) and a waste part (302), wherein the transfer belt can be guided to the winding (12) and the waste part (302) to a pulper (210).

13. Machine according to claim 12, characterized in that the tip cutter (55) has at least one compressed air nozzle (56) which is movable in the machine transverse direction (CD).

14. Machine according to claim 13, characterized in that at least one compressed air nozzle (56) is arranged inclined in the machine direction (MD), wherein the compressed air jet (56a) is directed forward in the machine direction (MD) and the angle of inclination (a) relative to the vertical (z) is 10° to 45°.

15. Machine according to at least one of claims 12 to 14, characterized in that it is designed to carry out the method according to at least one of claims 1 to 11. - 33 - 16. Machine according to at least one of claims 12 to 15, characterized in that the machine (1 ) comprises a winding unit (12) at the end in the machine direction (MD) for winding up the produced fiber web (309) and that the machine (1 ) comprises a pulper (210) into which a waste part (302) can be discharged in the manufacturing process.

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