Fabric for web production machine and method of making same

Abstract

A fabric for a machine for producing a fibrous web, the fabric comprising a woven chassis comprising a first base element and a second base element wherein the first base element comprises a first plain woven base material and the second base element comprises a second plain woven base material, wherein the first plain weave base material has a length that is twice the length of the fabric and is folded in the middle to produce a first two-layer element and a first fold, and wherein the second plain weave base material also has a length that is twice the length of the fabric and is folded in the middle to produce a second two-layer element and a second fold, and wherein the first base element and the second base element are arranged such that at least one layer of the first two-layer element is positioned between layers of the second two-layer element.

Description

Technical Field

[0001] The invention relates to a fabric for a machine for producing a fiber web and to a method for producing such a fabric. Background Art

[0002] Paper machine fabrics are used to form, transport, dewater and dry paper on a paper machine. Paper machine press felts are designed to transport the aqueous paper web through the press rolls of a paper machine and to aid in the dewatering of the paper web. Typically, paper machine wet press felts are constructed of a woven base fabric having a fibrous batt material needled to one or both sides.

[0003] Especially for many board and packaging paper machine press positions, void volume throughout life is a key press felt requirement for good performance. Many of these positions are sensitive to seam marks and therefore require seams with uniform dewatering and good structural integrity to achieve full life performance.

[0004] The amount of void volume within the base fabric of a press felt is directly related to the amount of water handled inside the felt as it conveys the paper web through the press nip. A felt that can run behind the nip without puddling is less likely to cause crushing or damage to the water-laden paper web. In some cases, multiple layers of base fabric are provided to increase the void volume of the press felt. Fabrics for paper machines can be made by endless weaving without seams. In this case, when the fabric is installed, the operating machine must be partially disassembled so that the fabric can be slid onto the machine from the side. This is a slow and cumbersome installation method because endless wet felts are relatively heavy and rigid and are typically several meters wide and over 30 meters long. In addition, not all papermaking equipment is designed to allow installation of non-seam fabrics.

[0005] To simplify installation, press fabrics with seams have gained acceptance. It is easier to run a flat, open-ended fabric through a paper machine and then join the opposite ends of the fabric together in a seam on the machine than to perform the tedious task of installing a non-seamed fabric.

[0006] Various seams and stitching methods are known in the art. Plain woven fabrics have been constructed with separate seam structures attached to the ends of the fabric, such as by sewing webbing strips to the fabric or using clamp hooks. In addition, papermaking fabrics are often formed from loops of yarn extending from the ends of the fabric, the loops from both ends of the fabric being interwoven and joined together by inserting a rudder thread or pin through the interwoven end loops to secure the ends together.

[0007] From an economic point of view, the fabric should be fast and easy to produce. Thus, for example, it is known from document WO 2009 / 106182 A1 to use a simple flat woven material and fold it, thereby creating a double-layer base structure with seaming loops for an on-machine-seamable fabric. The use of a flat woven material is advantageous because it can be easily produced on relatively simple and inexpensive looms and the production time is much faster compared to the endless weaving technology.

[0008] The production of seams for such fabrics is described in more detail in document WO 2013 / 083468 A1.

[0009] Unfortunately, in some applications, the double-layer design as described in documents WO 2009 / 106182 A1 and WO 2013 / 083468 A1 does not provide enough void volume to ensure adequate dewatering performance.

[0010] A fabric as described at the outset and according to the preamble of claim 1 is known from US Pat. No. 6,283,165. This document teaches inserting a third layer of plain woven material inside a two-layer laminate base, thereby increasing the void volume of the fabric compared to a two-layer laminate base alone. However, in some applications, even this third layer may not provide sufficient void volume. Furthermore, this method makes it difficult to control the positioning of the insert, resulting in uneven seams. Summary of the invention

[0011] It is an object of the present invention to provide a fabric for a fiber web production machine, in particular a press felt, which has a high void volume, which utilizes only a flat woven material as base structure, which is on-machine seamable, and which provides improved seam uniformity.

[0012] This object is achieved by a fabric for a machine for producing a fiber web, the fabric comprising a woven base structure, the woven base structure comprising a first base element and a second base element, wherein the first base element comprises a first flat-woven base material and the second base element comprises a second flat-woven base material, wherein the first flat-woven base material has a length that is essentially twice the length of the fabric and is folded essentially in the middle, producing a first two-layer element and a first folded portion, wherein the second flat-woven base material also has a length that is essentially twice the length of the fabric and is folded essentially in the middle, producing a second two-layer element and a second folded portion, and wherein the first base element and the second base element are arranged so that at least one layer of the first two-layer element is positioned in a sandwich manner between two layers of the second two-layer element.

[0013] The object is also achieved by a method for manufacturing a fabric for a machine for producing a fiber web, the fabric comprising a woven base structure, the woven base structure comprising a first base element and a second base element, wherein the first base element comprises a first flat-woven base material and the second base element comprises a second flat-woven base material, wherein the first flat-woven base material and the second flat-woven base material both have a length that is substantially twice the length of the fabric, the method comprising: folding the first flat-woven base material substantially in the middle to produce a first two-layer element and a first folded portion, folding the second flat-woven base material substantially in the middle to produce a second two-layer element and a second folded portion, and arranging the first base element and the second base element so that at least one layer of the first two-layer element is positioned in a sandwich manner between two layers of the second two-layer element.

[0014] The dependent claims relate to advantageous embodiments of the invention.

[0015] In particular, as claimed in the invention, the object is achieved by a fabric as described above, wherein a first flat woven base material has a length substantially twice the length of the fabric and is folded substantially in the middle, thereby producing a first two-layer element and a first fold, wherein a second flat woven base material also has a length substantially twice the length of the fabric and is folded substantially in the middle, thereby producing a second two-layer element and a second fold, wherein the first base element and the second base element are arranged so that at least one layer of the first two-layer element is positioned in a sandwich manner between two layers of the second two-layer element. The term "substantially" should here mean that the corresponding flat woven base material does not have to be exactly twice as long as the final fabric and / or does not have to be folded exactly in the middle, but should deviate from the length or the middle by no more than 10%, advantageously no more than 5%, respectively. This concept according to the invention has manufacturing advantages. This 4-layer flat woven design of the base structure provides better seam uniformity through a more consistent manufacturing method than the current prior art. The base is constructed in a way that allows easier assembly of four layers of fabric without intermediate single-layer joining welds.

[0016] In a first advantageous embodiment of the invention, the first base element and the second base element are arranged so that only one layer of the first two-layer element is positioned in a sandwiched manner between the two layers of the second two-layer element. In other words, one layer of the first two-layer element is positioned in a sandwiched manner between the two layers of the second two-layer element, while the other layer of the first two-layer element is positioned outside the two layers of the second two-layer element, and vice versa, which means that one layer of the second two-layer element is positioned in a sandwiched manner between the two layers of the first two-layer element, while the other layer of the second two-layer element is positioned outside the two layers of the first two-layer element.

[0017] In an alternative second advantageous embodiment of the invention, the first base element and the second base element are arranged in such a way that the two layers of the first two-layer element are positioned in a sandwich manner between the two layers of the second two-layer element.

[0018] For easy installation in a web production machine, the fabric is advantageously on-machine-seamable. In particular, it may have a first seaming loop along a first widthwise edge formed by MD yarns of a first plain woven base material at a first fold, and a second seaming loop along a second widthwise edge formed by MD yarns of a second plain woven base material at a second fold.

[0019] In order to keep the structure in place during manufacture, it is proposed to at least temporarily fix the first flat woven base material to the second flat woven base material by at least one row of yarns which are sewn tightly and parallel to the first fold and / or the second fold. Welding or gluing can also be used to temporarily attach the bases to each other.

[0020] Furthermore, it is advantageous if the web-side layer, i.e. the layer of the first two-layer element or the second two-layer element located on the web side of the fabric, and / or the roll-side layer, i.e. the layer of the first two-layer element or the second two-layer element located on the roll side of the fabric, is slightly longer than the two intermediate layers, i.e. the two layers located in a sandwich manner between the web-side layer and the roll-side layer. As a result, the edges of the web-side layer and / or the roll-side layer can be slightly moved over the seam of the web side and / or the roll side, respectively, thereby covering the seam and reducing the risk of seam marks.

[0021] In order to increase the resistance to peeling and yarn abrasion, it is recommended that the MD yarns are bonded to the CD yarns of the first plain woven base material in the area extending along the free width direction edge of the first plain woven base material, and / or the MD yarns are bonded to the CD yarns of the second plain woven base material in the area extending along the free width direction edge of the second plain woven base material. MD is an abbreviation for machine direction, and CD stands for cross-machine direction.

[0022] Of course, the first flat woven base material and / or the second flat woven base material can include multiple layers of woven fabric. However, in order to keep the production process of the fabric simple, it is preferred that the first flat woven base material and / or the second flat woven base material (advantageously both flat woven base materials) include a single layer of woven fabric. For the same reason, it is preferred that the first flat woven base material and / or the second flat woven base material - advantageously both flat woven base materials - include a plain weave structure. A simple plain weave structure only includes a repeating pattern of one over the other that can be woven very quickly. Other options include any single layer type of base weave, or a combination of two different base weaves, one for each base layer.

[0023] In order to increase the ability of the fabric to store water from the fiber web, it is proposed that the fabric further includes a fiber batt material needled to at least one side of the woven base structure. Additionally or alternatively, the fiber batt material can be needled to a layer inside the woven base structure. The needling process can also help or ensure that the first flat woven base material and the second flat woven base material are firmly fixed to each other.

[0024] In a preferred embodiment of the invention, the fabric is a paper press felt.

[0025] Another aspect of the present invention relates to a method for manufacturing a fabric for a machine for producing a fiber web, in particular the fabric of the present invention as described above, which comprises a woven base structure having a first base element and a second base element, wherein the first base element comprises a first plain woven base material, and the second base element comprises a second plain woven base material, wherein the length of both the first plain woven base material and the second plain woven base material is substantially twice the length of the fabric, the method comprising the following steps: folding the first plain woven base material substantially in the middle, thereby producing a first two-layer element and a first folded portion; folding the second plain woven base material substantially in the middle, thereby producing a second two-layer element and a second folded portion; and arranging the first base element and the second base element so that at least one layer of the first two-layer element is positioned in a sandwich manner between two layers of the second two-layer element.

[0026] Advantageously, the method further comprises the step of at least temporarily fixing the first plain woven base material to the second plain woven base material by means of at least one row of yarns which is stitched tightly and parallel to the first fold and / or the second fold.

[0027] In order to make the fabric seamable on the machine and form corresponding seaming loops, it is recommended that the method further include the following steps: removing CD yarns from the first plain woven base material at the first folding portion to form a first seaming loop; and removing CD yarns from the second plain woven base material at the second folding portion to form a second seaming loop.

[0028] By means of such seaming loops, a flat, open-ended fabric can be passed through a web-making machine and then the opposite ends of the fabric can be joined together in a seam on the machine. To this end, i.e., to make the fabric endless, it is recommended that the method further comprises the steps of: interpenetrating the first seaming loop and the second seaming loop to form a seam passage; and inserting a pivot into the seam passage to make the fabric endless.

[0029] Other objects and advantages of the present invention will become apparent to those skilled in the art from the following description of the currently preferred embodiments.All drawings are schematic only. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1A shows a side view of a first flat woven and folded base material according to a first embodiment of the present invention;

[0031] Figure 1B shows a side view of a second flat woven and folded base material according to the first embodiment of the present invention;

[0032] Figure 1C Shows Figure 1A The first flat woven and folded base material and Figure 1B A side view of a combined arrangement of a second flat woven and folded base material;

[0033] Figure 1D shows a PCB with some additional pins Figure 1C A side view of the arrangement;

[0034] Figure 2A shows a side view of a first flat woven and folded base material according to a second embodiment of the present invention;

[0035] Figure 2B shows a side view of a second flat woven and folded base material according to a second embodiment of the present invention;

[0036] Figure 2C Shows Figure 2A The first flat woven and folded base material and Figure 2B A side view of a combined arrangement of a second flat woven and folded base material;

[0037] Figure 2D shows a PCB with some additional pins Figure 2C Side view of the arrangement. DETAILED DESCRIPTION

[0038] Figures 1A-1D It is a schematic diagram showing the manufacturing process of the first preferred embodiment of the fabric according to the present invention.In fact, such fabrics of modern fiber web making machines can have a width from 5 feet to more than 33 feet and a length from 40 feet to more than 400 feet.

[0039] Figure 1A A first flat woven base material 10 is shown having a length substantially twice the length of the final fabric and being folded substantially in the middle, thus creating a first two-layer element having a first layer 12 and a second layer 14 connected to each other by a first fold 16. Thus, the first flat woven base material 10 forms a first base element 100. Advantageously, the first flat woven base material 10 presents a simple single-layer plain weave structure.

[0040] Similarly, Figure 1BA second plain woven base material 20 is shown, which also has a length substantially twice the length of the final fabric and is folded substantially in the middle, thus creating a second double layer element having a first layer 22 and a second layer 24 connected to each other by a second fold 26. Thus, the first plain woven base material 20 forms a second base element 200. Advantageously, the second plain woven base material 20 also presents a simple single layer plain weave structure.

[0041] Figure 1C An arrangement of a first base element 100 and a second base element 200 is shown, wherein in this particular embodiment the first base element 100 and the second base element 200 are arranged in such a way that at least the second layer 14 of the first two-layer element is positioned in a sandwich manner between the two layers 22, 24 of the second two-layer element. At the same time, the first layer 22 of the second two-layer element is positioned in a sandwich manner between the two layers 12, 14 of the first two-layer element. Thus, the arrangement has four layers stacked one above the other.

[0042] To make an on-machine-seamable fabric, the CD yarns at the first fold 16 are removed from the first plain woven base material 10 so that the MD yarns at the first fold 16 form a first seaming loop along the first widthwise edge of the fabric, and the CD yarns at the second fold 26 are removed from the second plain woven base material 20 so that the MD yarns at the second fold 26 form a second seaming loop along the second widthwise edge of the fabric. When the final fabric passes through a web-making machine, it can be easily made into an endless shape by interlacing the first seaming loop and the second seaming loop to form a seaming channel and by inserting a pivot into the seaming channel.

[0043] like Figure 1D As shown, the first plain woven base material 10 can be at least temporarily secured to the second plain woven base material 20 by rows of yarns 310 stitched adjacent and parallel to the first fold 16 and the second fold 26, respectively. Thus, the woven base structure 300 of the fabric is substantially complete.

[0044] Advantageously, particularly if the fabric is to be used as a press felt, the batt material is needled onto at least one side of the woven base structure 300 .

[0045] As can be seen in the drawings, the first and second plain woven base materials 10, 20 are not precisely folded in the middle thereof, resulting in the first layer 12 of the first plain woven base material 10 being slightly longer than the second layer 14 of the first plain woven base material 10, and the first layer 22 of the second plain woven base material 20 being slightly shorter than the second layer 24 of the second woven base material. This allows the free ends of the longer layers 12 and 24 to move slightly over the seams on both the web side and the roll side of the fabric, thereby reducing the risk of seam marks.

[0046] Figures 2A-2D It is only a schematic diagram to illustrate the manufacturing process of the second preferred embodiment of the fabric according to the present invention. The second embodiment is very similar to Figures 1A-1D The first embodiment is shown, therefore the same reference numerals refer to the same elements, and only the differences between the two embodiments will be discussed below. For similar elements, reference is made to the above description of the first embodiment.

[0047] In this embodiment, the first flat woven base material 10 and the second flat woven base material 20 are substantially folded in the middle of each of them, wherein the length of the second flat woven base material 20 is slightly less than the length of the first flat woven base material 10. In addition, both the first layer 22 and the second layer 24 of the second flat woven base material 20 are positioned in a sandwich manner between the first layer 12 and the second layer 14 of the first flat woven base material 10. This allows the free ends of the two layers 12 and 14 of the first flat woven base material to move slightly over the seams on both the web side and the roll side of the fabric, thereby reducing the risk of seam marks.

[0048] Reference Symbols and Names

[0049] 10First plain woven base material

[0050] 12 First layer of first plain woven base material 10

[0051] 14 Second layer of first plain woven base material 10

[0052] 16 first folding portion

[0053] 20 Second plain weave base material

[0054] 22 First layer of second plain woven base material 20

[0055] 24 Second layer of second plain woven base material 20

[0056] 26 second folding portion

[0057] 100 First Basic Components

[0058] 200 Second basic element

[0059] 300 Woven Base Structure

[0060] 310 rows of yarn (stitches)

Claims

1. A fabric for a machine for producing a fiber web, the fabric comprising: a woven base structure comprising a first base element and a second base element, wherein the first base element comprises a first flat-woven base material and the second base element comprises a second flat-woven base material, wherein the first flat woven base material has a length of approximately twice the length of the fabric and is folded approximately in the middle, thereby creating a first two-layer element and a first fold, wherein the second flat woven base material also has a length approximately twice the length of the fabric and is folded approximately in the middle, thereby creating a second two-layer element and a second fold, and The first base element and the second base element are arranged such that at least one of the first two-layer elements is positioned in a sandwich manner between two layers of the second two-layer element.

2. The fabric according to claim 1, wherein the first base element and the second base element are arranged such that only one layer of the first two-layer element is positioned in a sandwich manner between two layers of the second two-layer element.

3. The fabric according to claim 1, wherein the first base element and the second base element are arranged such that the two layers of the first two-layer element are positioned in a sandwich manner between the two layers of the second two-layer element.

4. The fabric of claim 1 , wherein the fabric is on-machine-seamable, having a first seaming loop along a first widthwise edge, the first seaming loop being formed by MD yarns of a first plain woven base material at a first fold, and having a second seaming loop along a second widthwise edge, the second seaming loop being formed by MD yarns of a second plain woven base material at a second fold.

5. The fabric of claim 1, wherein the first plain woven base material is at least temporarily secured to the second plain woven base material by at least one row of yarns stitched proximate to and parallel to the first fold or the second fold.

6. The fabric according to claim 1, wherein the fiber web side layer, i.e., the layer of the first two-layer element or the second two-layer element located on the fiber web side of the fabric, or the roll side layer, i.e., the layer of the first two-layer element or the second two-layer element located on the roll side of the fabric, is slightly longer than the two middle layers, i.e., the two layers located in a sandwich manner between the fiber web side layer and the roll side layer.

7. The fabric according to claim 1, wherein the MD yarns are bonded to the CD yarns of the first plain woven base material in an area extending along the free width direction edge of the first plain woven base material, or the MD yarns are bonded to the CD yarns of the second plain woven base material in an area extending along the free width direction edge of the second plain woven base material.

8. The fabric of claim 1, wherein the first plain woven base material or the second plain woven base material has a single layer weave.

9. The fabric of claim 1, wherein the first plain woven base material or the second plain woven base material has a plain weave structure.

10. The fabric of claim 1, further comprising: A fibrous batt material is needled into at least one side of the woven chassis.

11. The fabric of claim 10, wherein the fabric is a papermaking press felt.

12. A method of making a fabric for a machine for producing a fiber web, the fabric comprising a woven base structure, the woven base structure comprising a first base element and a second base element, wherein the first base element comprises a first flat woven base material and the second base element comprises a second flat woven base material, wherein both the first flat woven base material and the second flat woven base material have a length that is substantially twice the length of the fabric, the method comprising: folding the first flat woven base material substantially in the middle to create a first two-layer element and a first fold, folding the second flat woven base material substantially in the middle to create a second two-layer element and a second fold, and The first base element and the second base element are arranged such that at least one layer of the first two-layer element is positioned in a sandwich manner between two layers of the second two-layer element.

13. The method according to claim 12, further comprising: The first flat woven base material is at least temporarily secured to the second flat woven base material by at least one row of yarns that is stitched proximate to and parallel to the first fold or the second fold.

14. The method according to claim 12, further comprising: removing CD yarns from the first plain woven base material at a first fold to form a first seaming loop; and The CD yarns are removed from the second plain woven base material at the second fold to form a second seaming loop.

15. The method according to claim 14, further comprising: The first sewing loop and the second sewing loop are inserted into each other to form a seam channel; and A pivot is inserted into the seam channel to convert the fabric into a loop form.

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