EP4010528A1

EP4010528A1 - Basic structure of a fabric for a machine for producing or processing a fibrous web, and method for producing said basic structure

Info

Publication number: EP4010528A1
Application number: EP20743596.7A
Authority: EP
Inventors: Robert Eberhardt; Susanne Klaschka
Original assignee: Voith Patent GmbH
Current assignee: Voith Patent GmbH
Priority date: 2019-08-09
Filing date: 2020-07-03
Publication date: 2022-06-15
Also published as: WO2021028116A1; CN114174590A; US11952717B2; DE102019121485B3; JP7577732B2; US20220298727A1; MX2022001487A; JP2022543693A

Abstract

The invention relates to a basic structure of a fabric for a machine for producing or processing a fibrous web, in particular a paper, cardboard or tissue web, comprising at least a first flat fabric of fabric type A and a second flat fabric of fabric type B, wherein, furthermore, the basic structure comprises two loop elements, wherein the loop elements are formed in each case from a flat fabric piece which has a first portion of fabric type A and a second portion of fabric type B, and wherein the first portion is laid down on the second portion in such a way that the folding point is configured at a spacing of less than 5 cm, in particular less than 1 cm, from the changeover position between fabric type A and fabric type B, and wherein the first and the second flat fabric are arranged above one another, and the two loop elements are arranged in each case at a face-side end.

Description

BASIC STRUCTURE OF A COVERING FOR A MACHINE FOR THE MANUFACTURING OR PROCESSING OF A FIBER WEB AND THE PROCESS FOR THEIR MANUFACTURING

The invention relates to the basic structure of a covering for a machine for producing or processing a fibrous web according to the preamble of claim 1, a covering according to the preamble of claim 9, and a method for producing a basic structure according to the preamble of claim 10 Similar systems often have a basic structure which gives the covering stability and, when the system is in operation, absorbs forces, in particular tensile forces, which act on the covering. A large part of the basic structures used today consists wholly or partly of fabrics.

Circular weaving is a classic method of producing the endless fabric loops required. The endless structure is produced directly on the loom itself and has no seam. However, circular weaving as a manufacturing process is very slow and complex. In addition, it must be known exactly how long the desired covering should be when weaving. Since every application position in a paper machine requires a very individual length of the clothing loop, such basic structures can only be produced for one specific order. As an alternative that overcomes these two difficulties, it was proposed some time ago to produce seam coverings based on flat fabrics. These are described in EP 0 425 523 or EP 2 788 546, for example. In the case of a flat woven fabric, the ends are laid on themselves, so that a two-layer structure is created. The folds can be made into seam loops by removing CD threads - which correspond to the weft threads in the loom. The two front ends of the double-layer structure can be connected by letting the seam loops interlock and connecting them with a pintle wire. This concept has proven to be very successful in recent years, as it allows the flat fabric to be produced quickly and stored on rolls. The desired length can then be removed from these rolls when the order is received and also shortened to the required width.

For some applications, however, it has proven to be disadvantageous that this concept is relatively inflexible. The two layers of the two-layer structure each consist of the same fabric. On the one hand, this leads to so-called moiré effects due to the superposition. On the other hand, the different requirements on the running side and paper side cannot be taken into account.

To avoid these problems, DE102016111769 suggests changing the weaving pattern of the flat fabric during the weaving process in such a way that the two layers of the two-layer structure each have a different weaving pattern. This allows moire effects to be reduced. However, the weave pattern must be changed at the fold so that the length of the covering must be known when the basic structure is produced.

It is therefore an object of the present invention to overcome the problems of the prior art.

In particular, it is an object of the present invention to propose a basic structure and its production method which both allows great flexibility in the design of the covering and whose components can nevertheless be produced largely independently of the dimensions of the covering.

The objects are completely achieved by a basic structure according to the characterizing part of claim 1 and a method for producing a basic structure according to the characterizing part of claim 10.

Advantageous designs are described in the subclaims. With regard to the basic structure, the object is achieved by a basic structure of a clothing for a machine for producing or processing a fibrous web, in particular a paper, cardboard or tissue web. The basic structure comprises at least a first flat fabric of fabric type A and a second flat fabric of fabric type B. The basic structure is characterized in that it further comprises two loop elements, these loop elements each being formed from a flat fabric piece that has a first section of fabric type A and one having second section of tissue type B, and wherein the first section is placed on the second section that the fold is formed at a distance of less than 5 cm, in particular less than 1 cm from the point of change between tissue type A and tissue type B, and both Flat fabric on top of each other, and the two loop elements are each arranged at a front end. The basic structure therefore comprises at least four elements. The first and the second flat fabric usually represent the largest part of the basic structure. They are essentially designed as a homogeneous fabric and can advantageously be manufactured as roll goods regardless of the dimensions of the later covering, and can be cut from the roll when the covering is manufactured .

The change between fabric type A and fabric type B in the basic structure takes place at the fold, as in DE102016111769. In contrast to this prior art, the basic structure of the present invention each comprises its own loop element in which the folding takes place. These loop elements are essentially independent of the length of the later covering, and can be produced and kept in stock in standardized formats.

Thus, the basic structure can be made from elements that can be pre-produced either as rolled goods or as standardized loop elements. Nevertheless, the invention allows the flexibility to realize the two layers of the two-layer structure with different types of fabric. Thus can Moire effects are avoided or at least reduced, and the different requirements on the paper side and running side are taken into account.

As described, a piece of flat fabric is folded to form a loop element. A fold is thus formed at one end of the loop element. At the other end of the loop element, the two front edges of the original piece of flat fabric come to rest. One front edge is of fabric type A and the other front edge is of fabric type B. The first section and the second section can have the same length. However, it will often be advantageous if these two sections have different lengths. The length ratio is preferably between 40% / 60% and 30% / 70%. In the case of a flat fabric piece with a length of, for example, 2 m, the first section can be 1.20 m and the second section 0.80 m long.

The different lengths have the advantage that when later folding the front edges do not come to lie directly on top of one another, but are offset.

The flat woven fabrics and pieces of flat woven fabric used are usually woven from threads which consist entirely or partially of a polymer material. Polyamides, polyesters or polyethylene are common here. It is particularly advantageous if, in the first loop element and / or the second loop element, the front edge of fabric type A is or are connected to the first flat fabric and the front edge of fabric type B is or are connected to the second flat fabric. The connection of the loop elements with the first and the second flat woven fabric creates a coherent basic structure. This is on the one hand easier to process into a covering. On the other hand, such a basic structure not only provides transverse stability, but can also absorb tensile forces.

With this type of connection, it is very useful that on one side of the basic structure there is exclusively fabric type A, and on the other only fabric type B.

Such a connection is also called a join ‘. To achieve a basic structure and a covering with properties that are as homogeneous as possible, it is usually helpful if properties such as the permeability or thickness in the area of the join are largely matched to the properties outside this connection zone, so that they are in the area between 80% and 120% of the corresponding Values are outside the connection zone. Possibilities for realizing such joins are described, for example, in the document WO 2019/063518.

Furthermore, it can advantageously be provided that CD threads are removed in the area of the folds of the loop elements with the formation of seam loops, in particular 3 to 8 CD threads per fold are removed.

If such seam loops are formed on both sides of the two-layer structure, they can be guided into one another and connected by means of a pintle wire, whereby the basic structure or the entire covering can be made endless.

In order to enable easy threading of the pintle wire, the largest possible inside diameter of the seam loops is desirable.

To determine the inside diameter of a seam loop, the largest circle that can be completely inserted into the seam loop is determined. The diameter of this circle is then considered to be the inside diameter of the seam loop. However, a diameter that is too large leads to very thick seam loops which can possibly produce markings in the fibrous web. It has proven to be advantageous if the inside diameter of the seam loops is between 0.8 mm and 2.2 mm, preferably between 1 mm and 1.6 mm.

The size of the inside diameter of the seam loop is strongly influenced by the number of CD threads that are removed to form the seam loops. The advantageous inner diameters described can usually be implemented quite easily by removing 3-8 CD threads. If only one or 2 CD threads are removed, the seam loops will tend to have a smaller diameter in many applications. If more than 8 threads are removed, there is a risk that the diameter of the seam loops will be too large.

The inside diameter of the loop is also dependent on the thread diameter of the MD threads. The range [0.8-2.2 mm] is particularly valid for MD threads with diameters between 0.3mm and 0.6mm. MD threads of this type are typical for the base fabric of clothing for paper machines. With different yarn diameters, loop inside diameters outside the specified range are also conceivable.

In addition, it can be advantageous if CD threads ("special threads") are provided in the immediate vicinity of the seam loops, which do not occur in either type A or type B fabric. These special threads can either already be woven into the flat fabric piece or added later when the seam loops are formed. Since when creating the piece of flat fabric for the loop elements it is already determined where in the later loop element the seam loop will be positioned - namely at the transition between fabric type A and fabric type B - the special threads can easily be woven in when the piece of flat fabric is folded in. Examples of possible special threads are twisted threads, multifilaments, or threads with a non-round cross section, for example flat threads. Furthermore, special threads in the form of absorbent threads can be provided. In particular, the special threads the other CD threads of the The material and shape of the fabric correspond to the type of fabric, but by taking appropriate measures we can e.g. add an absorber additive for light in a certain wavelength range - especially in a section of the NIR range between 780 nm and 1200 nm. Such absorbent CD threads can be welded to the MD using laser transmission - threads are welded. This gives the seam loops a certain stability. Since MD threads - especially if they are made of a polyamide - do not absorb the laser light, they are only heated up during welding through contact with the CD threads. This does not significantly affect their strength

As an alternative or in addition, such special threads can also be provided at other locations on the flat fabric pieces or the loop elements. In particular, on or in the immediate vicinity of the front edges, such special threads in the form of absorbent threads can be very advantageous. As a result, the connection of the loop elements to the flat fabrics can be simplified by welding. Here, too, it proves to be an advantage that it is already known when weaving the flat fabric pieces for the seam loops at which point the join connection will be made. This means that the - usually more expensive - special threads only have to be woven in at the places where they are actually needed.

A fabric that has been woven into or otherwise provided with individual marker threads or other special threads - especially less than 10 - in a fabric of fabric type A (or B) should continue to be regarded as fabric of fabric type A (or B).

Advantageously, it can be provided that the fabric types A and B differ in at least one parameter, in particular have a different weave pattern or a different CD thread density. This allows a particularly high degree of flexibility in the design of the covering. However, this is not absolutely necessary. In alternative designs it can also be provided that the fabric type A is the same as the fabric type B. Such basic structures are also possible according to one aspect of the present invention.

In some embodiments, it can be advantageous if the basic structure comprises several flat fabrics of fabric type A and / or several flat fabrics of fabric type B. In particular, a basic structure can be built up from six elements, namely two flat fabrics of fabric types A and B as well as two loop elements. It can preferably be provided that the fabric type A and / or the fabric type B have an MD thread density between 30% and 45%, in particular between 34% and 42%, especially between 36% and 40%.

It is particularly preferable for both fabric types to have completely or largely the same MD thread density. The latter is advantageous from a production point of view. The flat woven fabrics for the loop elements can be produced on a loom, and both types of fabric use the same warp threads, which then make the MD threads available in the basic structure. At the point of change between the two types of fabric, the weaving pattern or the weft thread material can be changed relatively easily. However, changing the warp threads is very difficult. On the other hand, the seam loops, which are formed by the MD threads at the folds, can also be more easily inserted into one another, making the basic structure more easily endless.

The (MD) thread density indicates what proportion of the width of the fabric is taken up by (MD) threads.

If, for example, 8 threads per cm are provided and a thread has a diameter of 0.4 mm, the thread density is (8 * 0.4) / 10 = 32%. On the one hand, the specified range of MD thread density allows the seam loops to be fed into one another fairly easily. It should be noted that in the area of this seam, the MD threads of both seam loops create a loop density that corresponds to twice the MD thread density. With an MD thread density of 45%, this results in a loop density of 90%. This is close to the theoretical maximum density of 100%. Loop densities even greater than 90% are very difficult to handle and therefore not advantageous. An MD thread count of less than 30% on the other hand is not critical from the point of view of loop density. However, the properties of the fabric, such as tensile strength, usually suffer from this so much that the value should usually not be undershot without risking other disadvantages.

Coverings for paper and pulp machines and their basic structures are often subjected to a thermal treatment in a so-called “heat setting” process. The warp thread density in the finished covering or basic structure is usually higher than before the fleatsetting due to the resulting shrinkage process. The specified spans for the MD thread count are advantageous for both before and after the fleatsetting. With regard to the covering, the object is achieved by a covering, in particular a seam felt for a machine for forming or processing a fibrous web, in particular a paper, cardboard or tissue web, the covering comprising at least one basic structure according to one aspect of the invention. The covering can also include other components.

The covering is often provided with additional elements, such as fleece overlays, additional fabric elements, foils or foam elements. This depends on the later use of the resulting covering. In particular on the side of the covering touching the fibrous web, one or more layers of nonwoven fibers can be provided. In addition, the fleece fibers can also be provided on the running side. The nonwoven fibers are usually connected to the basic structure by needling. This is particularly advantageous because it also connects the individual components of the basic structure to one another, which further increases the strength of the covering.

With regard to the method, the object is achieved by a method for producing a basic structure according to one aspect of the invention, the method comprising the steps: a) providing a first flat fabric of fabric type A and a second flat fabric of fabric type B b) providing two flat fabric pieces, which have a first section of fabric type A and a second section of fabric type B and the formation of loop elements by laying the first section on top of the second section so that the fold is at a distance of less than 5 cm, in particular less than 1 cm, from the point of change between fabric type A. and tissue type B is formed. c) Arranging the first and the second flat fabric one above the other, and the two loop elements each at a front end.

In advantageous embodiments, the method can also include the step: d) connecting the loop elements to the first and second flat woven fabric, in such a way that the front edge of fabric type A with the first flat woven fabric and the front edge of the first loop element and the second loop element of the fabric type B connected to the second flat fabric, in particular welded

When executing the method, it should be noted that the sequence of the method steps can also be reversed if necessary. So is For example, the connection of the loop elements or the flat fabric pieces with the first / second flat fabric is possible both before the folding and shaping of the loop elements and afterwards. Furthermore, one or more fleatsetting steps can be provided in advantageous embodiments of the method. Many variations are conceivable here.

Thus, the first flat woven fabric can be subjected to fleatsetting before and / or after being provided in step a).

Alternatively or in addition, the second flat woven fabric can be subjected to fleatsetting before and / or after being provided in step a).

Alternatively or in addition, the flat fabric pieces from which the loop elements are formed can also be subjected to a fleat setting before and / or after being provided in step b). For example, it can be advantageous if the fabric of the flat fabric pieces is pre-produced in the form of a roll product, and this wool fabric is already subjected to a fleat setting, that is, before the individual flat fabric pieces are separated.

On the basis of exemplary embodiments, further advantageous features of the invention are explained with reference to the schematic drawings.

FIGS. 1a and 1b show a piece of flat fabric or a loop element according to one aspect of the invention

FIG. 2 shows a basic structure according to an aspect of the invention. FIG. 2a shows a basic structure according to a further aspect of the invention. FIG. 3 shows a fabric for use in a method according to a further aspect of the invention

FIG. 1 a shows a piece of flat woven fabric 6 which can serve as the basis for setting a loop element 2. The flat fabric piece 6 consists of one first section 6a, which is of fabric type A, and a second section 6b, which is of fabric type B. It can advantageously be provided that fabric type A and fabric type B differ in at least one parameter, in particular have a different weave pattern or a different CD thread density. In terms of production, it is very advantageous if both types of fabric have the same MD thread count. Sometimes it can also be provided that the fabric type A is the same as the fabric type B.

In order to have a high degree of flexibility in the production of basic structures 1 or coverings, the piece of flat fabric should have a short length in MD compared to the basic structure. In particular, the flat fabric piece 6 can be made shorter than 5 m, preferably 2 m or shorter.

The first section 6a and the second section 6b can have the same length. However, it will often be advantageous if these two sections 6a, 6b have different lengths. The length ratio is preferably between 40% / 60% and 30% / 70%. In the case of a flat fabric piece 6 with a length of, for example, 2 m, the first section 6a can be 1.20 m long and the second section 6b can be 0.80 m long.

The different lengths have the advantage that when later folded the front edges 3a, 3b do not come to lie directly on top of one another, but are offset. In order to form a loop element 2 from a piece of flat fabric 6, the piece of flat fabric can be folded and placed on itself. This is shown in Figure 1b. The folding point 4 is arranged in the region of the changing point 60, in particular at the changing point 60. In order to form seam loops 5, which later serve to make the basic structure 1 or the covering endless, CD threads can be removed from the fold. It is often sufficient to remove between 3 and 8 CD threads. The CD threads can be removed from fabric type A and fabric type B. But if, for example, the removal from a tissue type is more complicated than from the other, CD threads can only be removed from one type of fabric. If, as shown in FIG. 1b, the two sections 6a, 6b have different lengths, the front edges 3a, 3b do not come to lie on top of one another, which can be advantageous for subsequent further processing.

The two layers of the loop element 2 can advantageously be connected to one another. Such a connection can be made by one or more sewn connections 7, for example. Such a connection or sewing is advantageous, inter alia, because the two layers of the loop element 2 cannot be shifted against one another during further processing.

A connection in the area of the seam loop 5, for example at a distance of less than 2 cm from the seam loop 5, can also be advantageous in order to fix the seam loop 5 and later enable two seam loops 5 to be more easily inserted into one another to make the basic structure 1 endless.

FIG. 2 shows a basic structure 1 according to one aspect of the invention. This basic structure is formed from a first flat fabric 10 of fabric type A and a second flat fabric 20 of fabric type B, as well as two loop elements 2a, 2b. The loop elements 2a, 2b can in particular be designed as described in FIG. 1a or 1b.

The first flat woven fabric 10 and the second flat woven fabric 20 are arranged one above the other. Similar to the loop elements 2, 2a, 2b, these two layers 10, 20 can also be connected to one another, in particular sewn. The sewing connections 7 are not shown explicitly in FIG. 2, but can nevertheless be present. To form a coherent basic structure 1, the four components in the figure are connected to one another. In the loop elements 2a, 2b, the front edge 3a of fabric type A is connected to the first flat fabric 10, and the front edge 3b of fabric type B is connected to the second flat fabric 20. This connection 8 can take place in particular in the form of a weld 8. The welding can be done for example by laser welding, in particular by laser transmission welding, or by ultrasonic welding. Alternatively or additionally, the connection 8 can also be implemented in the form of an adhesive connection or a sewing connection. The resulting basic structure 1 has two seam loops 5a, 5b. The basic structure 1 can be made endless by joining these seam loops 5a, 5b and then inserting a pintle wire. Often the basic structure 1 is provided with further elements before it is made endless (or also afterwards), such as, for example, fleece overlays, additional fabric elements, foils or foam elements. This depends on the later use of the resulting covering.

While a basic structure 1 made of four woven elements, as shown in FIG. 2, is generally advantageous, it is nevertheless possible and provided that the basic structure is made up of more elements. An example of this is shown in Figure 2a. The basic structure 1 specified there differs from the basic structure 1 from FIG. 2 in that, in addition to the first flat woven fabric 10 and the second flat woven fabric 20, it has a further first flat woven fabric 11 and a further second flat woven fabric 21. The two flat fabrics of the same fabric type can also be connected to one another in a suitable manner, for example with a weld 8a. This can be advantageous, for example, if the flat fabrics are not in the form of — quasi endless — roll goods, but rather as prefabricated pieces of fabric of fixed length. In such a case, in addition to the first (second) flat woven fabric 10 (20) and the further first (second) flat woven fabric 11 (21), further flat woven fabrics are required in an analogous manner in order to build up the basic structure therefrom. Using the example of FIG. 3, one of the advantages that coverings have according to one aspect of the invention will be explained again. By separating the loop elements 2, 2a, 2b from the flat fabrics 10, 20, it is possible to produce these woven parts of the basic structure 1 without having to know the dimensions of the subsequent covering. FIG. 3 shows a fabric for this purpose, the weft direction of the loom corresponding to the CD direction of the later clothing, and the warp direction to the MD direction. In CD direction, the fabric can be produced in the maximum width of the available loom in order to be able to meet as many width requirements as possible for the future clothing. If narrower clothing is desired, this can be achieved by appropriate cutting. The resulting waste also occurs in today's fiering processes and does not represent a specific disadvantage of the present idea. In the MD direction, the fabric types A and B alternate in a regular pattern. The length of the flat fabric pieces 6 later required for the loop elements is used as a basis, together with the desired length ratio of the fabric types A and B. For example, it can be provided that the flat woven pieces 6 have a length of 2m, with the first section 6a having a length of 1 , 2m and the second section 6b has a length of 80 cm. The flat fabric pieces 6 and the sections 6a, 6b can also be provided longer or shorter. In any case, the fabric of FIG. 3 can be pre-produced as roll goods with the regular change of the fabric types A and B. To produce a basic structure 1, two pieces of flat fabric 6 can be removed from this roll and loop elements 2, 2a, 2b can be formed therefrom. The length required for the specific order or the basic structure 1 can then be set independently of the loop elements by means of a suitable length of the first flat fabric 10 and the second flat fabric 20. List of reference symbols

1 basic structure

2, 2a, 2b loop element 3a, 3b frontal edge

4 fold

5 seam loop

6 pieces of flat weave

6a first section 6b second section

7 sewing connection

8 weld seam

10, 11 first flat fabric 20, 21 second flat fabric 60 change point

Claims

1. Basic structure of a covering for a machine for the production or processing of a fibrous web, in particular a paper, cardboard or tissue web, comprising at least a first flat woven fabric of fabric type A and a second flat woven fabric of fabric type B, characterized in that the basic structure further comprises two loop elements The loop elements are each formed from a piece of flat fabric which has a first section of fabric type A and a second section of fabric type B, and the first section is laid on the second section in such a way that the fold is at a distance of less than 5 cm, is formed in particular less than 1cm from the point of change between fabric type A and fabric type B and wherein the first and the second flat fabric are arranged one above the other and the two loop elements are each arranged at a front end.

2. Basic structure according to claim 1, characterized in that in the first loop element and / or the second loop element the front edge of fabric type A is connected to the first flat fabric, and the front edge of fabric type B is connected, in particular welded, to the second flat fabric. are.

3. Basic structure according to one of the preceding claims, characterized in that CD threads are removed in the region of the folds of the loop elements with the formation of seam loops, in particular 3 to 8 CD threads per fold are removed.

4. Basic structure according to claim 3, characterized in that CD threads ('special threads') are provided in the immediate vicinity of the seam loops, which do not occur in either type A or B fabric.

5. Basic structure according to one of the preceding claims, characterized in that the fabric type A is the same as the fabric type B.

6. Basic structure according to one of claims 1 to 4, characterized in that the fabric types A and B differ in at least one parameter, in particular have a different weave pattern or a different CD thread density.

7. Basic structure according to one of the preceding claims, characterized in that the basic structure comprises several flat fabrics of fabric type A and / or several flat fabrics of fabric type B.

8. Basic structure according to one of the preceding claims, characterized in that the fabric type A and / or the fabric type B have an MD thread density between 30% and 45%, in particular between 34% and 42%.

9. Covering, in particular seam felt for a machine for setting or processing a fibrous web, in particular a paper, cardboard or tissue web, characterized in that the covering comprises at least one basic structure according to one of the preceding claims.

10. The method for producing a basic structure according to any one of claims 1 to 8, the method comprising the steps of: a) providing a first flat fabric of fabric type A and a second flat fabric of fabric type B b) providing two flat fabric pieces, which have a first section of Having fabric type A and a second section of fabric type B and forming loop elements by laying the first section on top of the second section so that the fold is formed at a distance of less than 5 cm, in particular less than 1 cm, from the point of change between fabric type A and fabric type B. . c) Arranging the first and the second flat fabric one above the other, and the two loop elements each at a front end.

11. The method according to claim 10, characterized in that the method also comprises the step: d) connecting the loop elements with the first and second flat woven fabric, such that the front edge of the fabric type A with the first loop element and the second loop element first flat fabric, and the front edge of fabric type B is connected to the second flat fabric, in particular welded.