Base structure, clothing, and method

Abstract

The present invention relates to a base structure for a clothing for use in a machine for producing or processing a fibrous web, comprising a fabric band with longitudinal threads and transverse threads interwoven with one another and with a first longitudinal end and a second longitudinal end, wherein the two longitudinal ends of the fabric band are connected to one another in a connection zone, wherein one or more transverse threads are removed at both longitudinal ends of the fabric band with the formation of free thread ends of the longitudinal threads, characterised in that at least at the first longitudinal end a plurality of free thread ends, in particular all free thread ends, run at least partially deviating from the longitudinal direction, and in that the free thread ends of the first longitudinal end and the free thread ends of the second longitudinal end are arranged in an overlapping manner in the region of the connection zone and are connected, in particular welded, to one another.

Description

[0001] Basic structure, covering and process.

[0002] The invention relates to a basic structure for a clothing for use in a machine for producing or processing a fibrous web according to the preamble of claim 1 as well as an associated clothing and a method for producing it.

[0003] Fabrics, especially felts, used in machines for the production or processing of fibrous webs, usually comprise a base structure on which one or more functional layers, e.g., in the form of nonwoven layers, are arranged. The base structure usually comprises one or more fabric layers.

[0004] To produce an endless fabric loop for such base structures, so-called circular fabrics are traditionally used. These can be used directly as an endless base fabric or, as described in FL 77072, formed into a double-layer loop, which is made endless with a seam.

[0005] However, the production of these circular weaves is very time-consuming, especially for long coverings. Furthermore, the dimensions of the finished covering must be precisely known during weaving.

[0006] For this reason, flat fabrics have recently been increasingly used, which are folded together to form two-layer fabric structures that can then be made endless by means of a seam. Such basic structures are described, for example, in EP 0 425 523 B1 or US Pat. No. 7,892,402 B2.

[0007] Typically, when using flat fabrics, the two longitudinal ends are joined together. A suitable joining method for this is welding, as described, for example, in WO14105376 A1 or by the applicant in EP 3,687,774 B1. The object of the invention is to provide a basic structure for a covering that is easy to manufacture and simultaneously exhibits very good properties, particularly strength properties.

[0008] The object is achieved according to the invention by an embodiment according to independent claim 1, a covering according to claim 9, and a method according to claim 10. Further advantageous embodiments of the present invention can be found in the subclaims.

[0009] A basic structure for a covering for use in a machine for producing or processing a fibrous web is proposed, comprising a fabric belt with interwoven longitudinal threads and transverse threads and with a first longitudinal end and a second longitudinal end, wherein the two longitudinal ends of the fabric belt are connected to one another in a connecting zone, wherein at both longitudinal ends of the fabric belt one or more transverse threads are removed to form free thread ends of the longitudinal threads.

[0010] According to the invention, it is provided that the longitudinal threads run essentially in the longitudinal direction of the basic structure, wherein at least at the first longitudinal end a plurality of free thread ends, in particular all free thread ends, run completely or at least partially deviating from the longitudinal direction, and that in the region of the connecting zone the free thread ends of the first longitudinal end and the free thread ends of the second longitudinal end are arranged overlapping and connected to one another, in particular welded.

[0011] The term "essentially in the longitudinal direction" should be understood to mean that during the production of the fabric, the aim is to align the longitudinal threads in the longitudinal direction (=machine direction). Due to the achievable accuracy, small deviations from the longitudinal direction may occur in individual or all longitudinal threads. However, these deviations are small and usually amount to less than 2°, in particular less than 1°. The longitudinal threads can, in particular, all be of the same type and preferably consist of monofilaments.

[0012] The cross threads can be monofilaments or twisted threads. They can all be of the same type. However, it is also possible for both twisted threads and monofilaments to be used as cross threads.

[0013] Basic structures according to aspects of the invention may comprise, in addition to the described fabric tape, further components, in particular further woven components.

[0014] An important goal in the design of such a connection zone is, on the one hand, to ensure a stable connection between the two longitudinal ends. On the other hand, the connection zone should not differ significantly from the rest of the fabric in important properties, especially its thickness.

[0015] WO14105376 A1 proposes overlapping the two fabric ends and then joining them using ultrasonic welding. The thickness and permeability of the joining zone are influenced by applying joining pressure and using a textured welding tool. However, this severely damages the filament structure in this area, and the joint becomes relatively brittle.

[0016] EP 3,687,774 B1, on the other hand, takes the approach of removing some transverse threads at the longitudinal ends and instead welding connecting elements to these free thread elements. While this approach can typically achieve good strength with low brittleness, achieving suitable permeability is complex.

[0017] In basic structures according to aspects of the present invention, some transverse threads are also removed from the fabric tape at the longitudinal ends. However, a connecting element can be dispensed with. Instead, some, in particular all, of the longitudinal threads are provided at at least one longitudinal end in such a way that they run entirely or partially deviating from the longitudinal direction. These longitudinal ends thus deviate from the remaining course of the longitudinal thread, which runs essentially in the longitudinal direction. In this way, it can be achieved that the thread ends of the two longitudinal ends overlap or cross over and can be welded together. Thus, a welded connection can be realized without the use of additional connecting elements, even if it would in principle be possible to use additional connecting elements even with basic structures according to aspects of the invention.

[0018] By appropriately deflecting or shaping the free thread ends on one or both, the structure, strength and permeability can be adapted to requirements over a fairly wide range.

[0019] For example, it may be advantageous if a plurality of free thread ends, in particular all free thread ends of the first longitudinal end, are arranged in an overlapping manner with several—e.g., two, three, four, or five—free thread ends of the second longitudinal end and are connected to one another, in particular welded. This can, for example, increase the tensile strength of the connection zone.

[0020] Furthermore, it may be advantageous if a majority—in particular all—of the free thread ends of the second longitudinal end extend deviating from the longitudinal direction. These free thread ends can also be arranged overlapping one or more—e.g., two, three, or four—free thread ends of the second longitudinal end and connected to one another, in particular welded.

[0021] This allows the structure, strength and permeability of the connection zone to be designed even more freely.

[0022] The deviation of the free thread ends from the longitudinal direction can be achieved in a variety of ways. Some advantageous embodiments are illustrated below as examples: In one embodiment, the majority of free thread ends of the first longitudinal end and / or the majority of free thread ends of the second longitudinal end can be deflected to one side. These thread ends can expediently be deflected to the same side.

[0023] The free thread ends can run straight after the deflection and have an angle of, for example, between 15° and 75°, preferably between 30° and 60°, particularly preferably between 35° and 45°, relative to the longitudinal direction.

[0024] As a rule of thumb, the larger the angle compared to the longitudinal direction, the more free thread ends of the opposite longitudinal end are overlapped, and the more connection points per thread end can be realized.

[0025] However, excessive deflection—especially over 75°—can be risky. For example, the thread ends can be damaged by kinking. Angles between 15° and 75°, and especially between 30° and 60°, have proven advantageous.

[0026] In particular, the deflected free thread ends of the first longitudinal end and the deflected free thread ends of the second longitudinal end can have the same angle or substantially the same angle with respect to the longitudinal direction or can have a different angle.

[0027] The manufacturing process can also lead to deviations from the desired angular deflection of individual thread ends due to the deflection of the thread ends. Such a manufacturing-related deviation of a few thread ends (e.g., < 20%) from the otherwise identical orientation of the remaining thread ends is referred to as a "substantially identical angle" in the context of this application.

[0028] Another possibility is for the plurality of free thread ends of the first longitudinal end and / or the plurality of free thread ends of the second longitudinal end to have a curved, in particular undulating, profile. For example, a undulating thread end can have multiple connection points with an opposite thread end. Alternatively or additionally, a curved, in particular undulating, thread end can also have multiple connection points with opposite thread ends.

[0029] Regardless of the course of the longitudinal threads, it may be advantageous for the longitudinal threads to have at least the same diameter as the transverse threads, wherein the diameter of the longitudinal threads is preferably between 100% and 150%, particularly preferably between 100% and 125% of the diameter of the transverse threads.

[0030] Threads with a circular cross-section, for example, have a diameter of 125%, which represents 156.25% of the cross-sectional area. Therefore, the above particularly preferred feature can also be formulated such that it is advantageous if the cross-sectional area of ​​the longitudinal threads is between 100% and 156.25% of the cross-sectional area of ​​the transverse threads. This allows even non-circular threads—for example, twisted threads—to be easily considered.

[0031] This dimensioning can be particularly advantageous if the fabric tape is woven in a plain weave or a similar weave.

[0032] Outside the connecting zone, the fabric tape has a thickness approximately equal to the thickness of the longitudinal threads plus the thickness of the transverse threads. If the free longitudinal thread ends are overlapped in the connecting zone, the resulting thickness is twice the thickness of the longitudinal thread. To achieve a uniform thickness of the fabric tape, it is advantageous if the diameter of the longitudinal threads and the transverse threads are approximately the same.

[0033] If the joining is done by welding, for example, it is possible to slightly reduce the thickness of the joining zone by applying a certain joining pressure during welding. This allows the longitudinal threads to have slightly larger diameters than the transverse threads.

[0034] In combination with a suitable orientation of the longitudinal threads, it is also relatively easy to achieve a bonding zone with approximately the same or only slightly higher material density—and thus only slightly lower permeability—than the rest of the fabric. Basic structures according to aspects of the invention can be used in various paper machine clothing, but they are particularly suitable as basic structures for press felts. For this purpose, the basic structures are usually needled on one or both sides with a nonwoven layer of staple fibers.

[0035] Such basic structures can be used in both seamed felts and endless felts. Their use in so-called hybrid felts is also possible. In these hybrid felts, the basic structure comprises not only one or more fabric bands, whose longitudinal ends are realized according to aspects of the invention, but also an endlessly woven circular fabric. The various fabric bands can then be arranged one above the other.

[0036] Furthermore, a method for producing a basic structure for a clothing is proposed, wherein the clothing is suitable for use in a machine for producing or processing a fibrous web. The method comprises the following steps: a. providing a fabric strip with interwoven longitudinal threads and transverse threads and with a first longitudinal end and a second longitudinal end, wherein one or more transverse threads are removed at both longitudinal ends of the fabric strip to form free thread ends of the longitudinal threads. b. deflecting a plurality of free thread ends, in particular all free thread ends at at least the first longitudinal end, so that they run deviating from the longitudinal direction, c. overlapping free thread ends of the first longitudinal end with free thread ends of the second longitudinal end d. joining, in particular welding, the overlapping thread ends in the region of the joining zone.

[0037] The welding can be carried out using various well-known welding processes.

[0038] For example, ultrasonic welding is possible. Laser welding, especially laser transmission welding, is also advantageous.

[0039] One possibility is the use of laser wavelengths in the range 800-1100 nm, which are only very weakly absorbed by conventional polymers. Suitable dyes or absorbers can be used at the points where a weld is to be created, so that energy is absorbed there. If the longitudinal threads do not already exhibit sufficient absorption even through the addition of suitable absorbers, the contact points can be treated with a suitable absorber (e.g., carbon black or "ClearWeld"). Such a welding process is described, for example, in WO2022 / 037832 A1.

[0040] If it is not possible or desired to add a dye to the plastic or to treat the welds accordingly, “clear-to-clear welding” is also possible.

[0041] In the range of 1700–2000 nm, most polymers absorb on their own. This absorption is weak, allowing the laser energy to penetrate deeper into the components. The strength of absorption at different wavelengths depends on the type of polymer. Depending on the type of polymer and component thickness, it may be advantageous to use either a wavelength of 1725 nm or 1940 nm.

[0042] In contrast to conventional laser welding, absorption does not only occur at the weld seam, but begins at the surface of the upper component and is effective across the entire component thickness. For thicker components (1-2 mm), the laser beam is therefore strongly focused on the weld seam. This means that although most of the laser energy is still absorbed at the surface, it is absorbed over a much larger area than at the weld seam. The melting of the plastic thus occurs primarily in the area of ​​the weld seam, but with a much greater depth and larger volume than with conventional laser welding. Accordingly, more laser energy is required and the process is significantly slower. Nevertheless, it can be used for thread connections according to aspects of the present invention, and depending on the application, it can also be an advantageous alternative when no absorbers are required.

[0043] The invention is explained below with reference to the figures. The figures show in detail:

[0044] Figures 1a and 1b show a fabric tape for a basic structure according to the prior art

[0045] Figures 2a and 2b show a fabric tape for a basic structure according to one aspect of the invention

[0046] Figures 3a and 3b show a fabric tape for a basic structure according to a further aspect of the invention

[0047] Figures 4a and 4b show a fabric tape for a basic structure according to a further aspect of the invention

[0048] Figures 4c and 4d show a fabric tape for a basic structure according to a further aspect of the invention

[0049] Figure 5 shows a basic structure according to a further aspect of the invention

[0050] Figure 6 shows a covering according to one aspect of the invention

[0051] The examples shown are intended to illustrate that basic structures according to aspects of the invention can be implemented in a variety of ways. The invention is not limited to these examples.

[0052] Figures 1a and 1b show the connection of the front ends of a fabric tape according to the prior art.

[0053] Figure 1a shows the two longitudinal ends 7a, 7b of a fabric tape 1. The fabric tape 1 is formed from longitudinal threads 2 and transverse threads 3. At both longitudinal ends 7a, 7b, free ends 6a, 6b of the longitudinal threads 2 are provided by removing some transverse threads 3.

[0054] Figure 1b now shows how these free ends 6a, 6b of the longitudinal threads 2 interlock in the region of the connecting zone 5. The thread density of the longitudinal threads 2 in the connecting zone 5 is essentially twice as high as in the rest of the fabric tape 1. In the connecting zone 5, several connecting elements 4 in the form of threads 4 are provided in Figure 1b, which are oriented in the transverse direction of the fabric tape 1. It can be seen that the connecting elements 4 are in contact with the free ends 6a, 6b of the longitudinal threads 2 and are welded.

[0055] This connects the two longitudinal ends 7a, 7b of the fabric band to each other, forming an endless loop. The force is transmitted solely via the connecting elements 4.

[0056] In contrast, Figures 2a and 2b show the connection of the front ends of a fabric tape 1 according to one aspect of the invention. The longitudinal threads 2 run between the longitudinal ends 7a, 7b again essentially in the longitudinal direction L of the fabric tape 1. In this case, the second longitudinal end 7b is designed analogously to Figure 1a. The free thread ends 6b here all run along the longitudinal direction L. At the first longitudinal end 7a, however, a majority of the free thread ends 6a, in particular all of the free thread ends 6a, deviate from the longitudinal direction L. They are deflected to one side. After the deflection, the free thread ends 6a can run in a straight line and can have an angle to the longitudinal direction L of, for example, between 15° and 75°, preferably between 30° and 60°, particularly preferably 45°.

[0057] As shown in Figure 2b, in the area of ​​the connecting zone 5, the free thread ends 6a of the first longitudinal end 7a and the free thread ends 6b of the second longitudinal end 7b are arranged overlapping and connected to one another, in particular welded. The deflection of the free thread ends 6a directly creates contact points 8 and thus connection points 8 between the free thread ends 6a, 6b of the two sides 7a, 7b. An additional connecting element 4, as described in the prior art, can be omitted.

[0058] In the example of Figures 2a and 2b, the free thread ends 6a of the first longitudinal end 7a run such that they each overlap or are connected to at least two free thread ends 6b of the second longitudinal end 7b. By changing the angle, more or fewer overlaps could be achieved here. Figures 3a and 3b differ from Figures 2a and 2b in that at the first longitudinal end 7a and the second longitudinal end 7b, a majority of the free thread ends 6a, 6b, in particular all free thread ends 6a, deviate from the longitudinal direction L and are deflected to one side. The angle ß of the deflection can be the same or different on both sides. In this example, the deflection on both sides resulted in the free thread ends 6a, 6b of both sides 7a, 7b each being connected to three free thread ends 6b, 6a of the opposite side, as can be seen in Figure 3b.Here again, no connecting element 4 is necessary.

[0059] More clearly than in Figure 2b, Figure 3b clearly shows that spaces in the shape of diamonds 9 form between the thread ends 6a, 6b. By changing the deflection angle ß, the shape and area of ​​these diamonds 9 can be varied. In this way, the permeability of the connecting zone 5 for water or air can be varied and, if desired, completely or largely matched to the values ​​of the remaining fabric tape 1.

[0060] Figures 4a and 4b show a further aspect of the present invention. Similar to Figures 2a and 2b, a majority of the free thread ends 6a, in particular all free thread ends 6a, deviate from the longitudinal direction L at the first longitudinal end 7a. In contrast to Figure 2a, however, these thread ends 6a do not run in a straight line, but rather have a curved course, in particular a wave-like course. In this way, connection points 9 are again formed between the thread ends 6a, 6b of the two sides 7a, 7b without the need for a connecting element 4.

[0061] Even if this is not explicitly shown in the figures, it is easily apparent to the person skilled in the art that, in addition, the free thread ends 6b can also assume a curved or wave-shaped course at the second longitudinal end 7b.

[0062] Figures 4c and 4c show a further variant according to an aspect of the invention. Here, the free thread ends 6a and 6b of the first longitudinal end 7a and the second longitudinal end 7b have a curved profile. In contrast to Figures 4a and 4b, the profile here is not wave-shaped; rather, the free thread ends are curved in only one direction. The curvature can be realized in the form of a circular segment or in another form. It is advantageous if the free thread ends 6a, 6b of a longitudinal end 7a, 7b have essentially the same curvature.

[0063] The manufacturing process can also result in deviations from the desired curvature of individual thread ends. Such a manufacturing-related deviation of a few thread ends (e.g., < 20%) from the otherwise identical orientation of the remaining thread ends is referred to as "essentially identical curvature" in the context of this application.

[0064] In this embodiment, the free thread ends 6a, 6b of both longitudinal ends 7a, 7b are deflected toward the same side of the fabric tape 1. Although this is not necessary to obtain the desired connection points 8, it can be produced more easily and efficiently.

[0065] Figure 5 shows a basic structure for a clothing for use in a machine for producing or processing a fibrous web. This basic structure comprises two fabric belts 1 which have been made into an endless loop by connecting the longitudinal ends 7a, 7b according to one aspect of the invention. The two fabric belts 1 are arranged one above the other to form a basic structure consisting of two fabric layers 1. For use as a press felt in a paper machine, this basic structure can also be provided on one or both sides with nonwoven layers 12 made of staple fibers. As shown in Figure 5, it can be advantageous if the two connecting zones 5 of the fabric belts 1 are not arranged directly above one another, but are spaced apart by a distance ö in the longitudinal direction L, which here corresponds to the machine direction MD. This distance ö should be greater than 10 cm, preferably greater than 50 cm, but can also be 2 m, 5 m or more.

[0066] In an alternative embodiment, one of the fabric bands 1, preferably the outer fabric band 1, can also be replaced with a circular fabric. Circular fabrics are woven directly on the loom as an endless fabric loop and therefore do not have a connecting zone 5. A basic structure with a combination of circular fabric and endless flat fabric is also referred to as a hybrid basic structure.

[0067] Figure 6 schematically shows a covering, specifically a seam felt according to one aspect of the invention. The fabric strip 1 with the connecting zone 5 is in the form of an endless loop. By laying the fabric loops on top of each other, a double-layered structure is created which has two folds 11. The double-layered structure created from the endless fabric strip 1 serves as the basic structure for the seam felt. As shown in Figure 5a, it can be provided with a nonwoven layer 12 on both the top and bottom sides. This is usually connected to the basic structure by needling. In advantageous embodiments of the invention, even after needling, the strength of the connecting zone 5 is at least 25%, in particular at least 50%, of the strength of the remaining fabric strip 1. It can be advantageous to arrange the connecting zone 5 at some distance from the folds 11.A distance of at least 5 cm, or even 10 cm, is very advantageous. Preferably, the connecting zone 5 can also be arranged approximately midway between the two folds. The seam loops 13 will be formed from the two folds 11. Typically, some transverse threads 3 are removed in the area of ​​the folds 11. These seam loops 13 are brought together. The covering can be made endless by connecting them with a so-called pintle. The connecting zone 5 in such a seam felt can be designed according to any desired embodiment of the invention. List of reference symbols.

[0068] 1 fabric tape

[0069] 2 longitudinal threads, MD threads

[0070] 3 cross threads, CD threads

[0071] 4 Connecting element

[0072] 5 Connection zone

[0073] 6a free thread end

[0074] 6b free thread end

[0075] 7a first longitudinal end

[0076] 7b second longitudinal end

[0077] 8 Connection point

[0078] 9 diamonds

[0079] 11 folding point

[0080] 12 fleece layers

[0081] 13 seam loop

[0082] L Longitudinal direction ß Angle of deflection ö Distance

[0083] MD Machine Direction

[0084] CD transverse direction

Claims

Patent claims 1. A basic structure for a covering for use in a machine for producing or processing a fibrous web, comprising a fabric belt (1) with interwoven longitudinal threads (2) and transverse threads (3) and with a first longitudinal end (7a) and a second longitudinal end (7b), wherein the two longitudinal ends (7a, 7b) of the fabric belt (1) are connected to one another in a connecting zone (5), wherein at both longitudinal ends (7a, 7b) of the fabric belt (1) one or more transverse threads (3) are removed to form free thread ends (6a, 6b) of the longitudinal threads (2), characterized in that the longitudinal threads (2) run essentially in the longitudinal direction of the basic structure, wherein at least at the first longitudinal end (7a) a plurality of free thread ends (6a), in particular all free thread ends (6a), run at least partially deviating from the longitudinal direction,and that in the region of the connecting zone (5) the free thread ends (6a) of the first longitudinal end (7a) and the free thread ends (6b) of the second longitudinal end (7b) are arranged overlapping and connected to one another, in particular welded., 2. Basic structure according to claim 1, characterized in that a plurality of free thread ends (6a), in particular all free thread ends (6a) of the first longitudinal end (7a) are each arranged overlapping with at least two free thread ends (6b) of the second longitudinal end (7b) and are connected to one another, in particular welded.

3. Basic structure according to one of the preceding claims, characterized in that a majority - in particular all - of the free thread ends (6b) of the second longitudinal end (7b) extend deviating from the longitudinal direction and these free thread ends (6b) are preferably each provided with at least two free Thread ends (6a) of the second longitudinal end (7a) are arranged overlapping and connected to one another, in particular welded.

4. Basic structure according to one of the preceding claims, characterized in that the plurality of free thread ends (6a) of the first longitudinal end (7a) and / or the plurality of free thread ends (6b) of the second longitudinal end (7b) are deflected to one side and have an angle of between 15° and 75°, preferably between 30° and 60°, particularly preferably from 35° to 45°, with respect to the longitudinal direction.

5. Basic structure according to claim 4, characterized in that the deflected free thread ends (6a) of the first longitudinal end (7a) and the deflected free thread ends (6b) of the second longitudinal end (7b) have substantially the same angle with respect to the longitudinal direction.

6. Basic structure according to claim 4, characterized in that the deflected free thread ends (6a) of the first longitudinal end (7a) and the deflected free thread ends (6b) of the second longitudinal end (7b) have a different angle with respect to the longitudinal direction.

7. Basic structure according to one of the preceding claims, characterized in that the plurality of free thread ends (6a) of the first longitudinal end (7a) and / or the plurality of free thread ends (6b) of the second longitudinal end (7b) have a curved course, in particular a wave-shaped course.

8. Basic structure according to one of the preceding claims, characterized in that the longitudinal threads (2) have at least the same diameter as the transverse threads (3), the diameter of the Longitudinal threads (2) is preferably between 100% and 150% of the diameter of the transverse threads (3).

9. Clothing, in particular press felt for use in a machine for producing or processing a fibrous web, wherein the clothing has a basic structure according to one of the preceding claims.

10. A method for producing a basic structure for a clothing for use in a machine for producing or processing a fibrous web, comprising the steps of: a. providing a fabric belt (1) with interwoven longitudinal threads (2) and transverse threads (3) and with a first longitudinal end (7a) and a second longitudinal end (7b), wherein at both longitudinal ends (7a, 7b) of the fabric belt (1) one or more transverse threads (3) are removed to form free thread ends (6a, 6b) of the longitudinal threads (2). b. deflecting a plurality of free thread ends (6a), in particular all free thread ends (6a) at at least the first longitudinal end (7a), so that they run deviating from the longitudinal direction, c. Overlapping free thread ends (6a) of the first longitudinal end (7a) with free thread ends (6b) of the second longitudinal end (7b) d.Connecting, in particular welding, the overlapping thread ends (6a, 6b) in the region of the connecting zone (5).

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