Papermaking fabric

Abstract

A papermaking fabric for fibrous web forming or processing machines extends in MD and CD-directions and includes top and bottom fabric layers bound by binder yarns. The top layer is a web contacting side with top weave structures having interwoven first MD and first CD-yarns. The bottom layer is a machine contacting side with bottom weave structures having interwoven second MD and second CD-yarns. The top weave structure has repeats and forms fiber compression areas and fiber support areas recessed in thickness direction of the fabric relative to the fiber compression areas on the web side and fiber support areas separated by fiber compression areas or vice versa. A fiber compression area has adjacent top MD-floats on the web side or adjacent top CD-floats on the web side and a fiber support area has first MD and first CD-yarns interwoven in plain weave.

Claims

1. A papermaking fabric extending in a MD-direction and in a CD-direction for a machine for at least one of forming or processing a fibrous web, the papermaking fabric comprising: a top fabric layer, a bottom fabric layer and binder yarns binding said top and bottom fabric layers together; said top fabric layer providing a web contacting side and having a top weave structure formed by interwoven first MD-yarns and first CD-yarns; said bottom fabric layer providing a machine contacting side and having a bottom weave structure formed by interwoven second MD-yarns and second CD-yarns; said top weave structure being repeated in top weave repeats, said top weave structure, per top weave repeat, forming one or more fiber compression area and one or more fiber support area recessed in a thickness direction of the fabric relative to said one or more fiber compression area on said web contacting side and fiber support areas being separated from each other by one or more fiber compression area or vice versa; i. said one or more fiber compression area being formed by a top MD-float or at least two adjacent top MD-floats on said web contacting side or said fiber compression area being formed by a top CD-float or at least two adjacent top CD-floats on said web contacting side, wherein said top MD-float or each of said at least two adjacent top MD-floats is formed by one of the first MD yarns passing over at least two adjacent ones of the first CD yarns, and said top CD-float or each of said at least two adjacent top CD-floats is formed by one of the first CD yarns passing over at least two adjacent ones of the first MD yarns; ii. said one or more fiber support area being formed by a plurality of said first MD-yarns interwoven in a plain weave with a plurality said first CD-yarns; and a honeycomb-shaped structure having an aspect ratio in a maximum extension in said MD-direction to a maximum extension in said CD-direction of between 0.25 and 4.

2. The papermaking fabric according to claim 1, wherein said top weave structure forms pockets, each of said pockets has a bottom part and an edge part partially or fully surrounding said bottom part, said one or more fiber support area provides the bottom parts of said pockets and said one or more fiber compression area provides said edge parts surrounding said bottom parts.

3. The papermaking fabric according to claim 2, wherein said edge part of at least some of said pockets is formed by said top MD-floats and by said top CD-floats.

4. The papermaking fabric according to claim 2, wherein a majority or each of said bottom parts is formed by two or at least three adjacent first MD-yarns interwoven in a plain weave sequence with at least two or at least three adjacent first CD-yarns.

5. The papermaking fabric according to claim 2, wherein at least some or all of said pockets have a maximum extension of 0.5 to 2.5 millimeters in said MD-direction and a maximum extension of 0.5 to 2.5 millimeters in said CD-direction.

6. The papermaking fabric according to claim 1, wherein said one or more fiber support area on average is recessed relative to said one or more fiber compression area by 30 m to 500 m or by 40 m to 200 m.

7. The papermaking fabric according to claim 1, wherein at least some of said first CD-yarns form top CD-floats on said web contacting side over at least three or at least four adjacent first MD-yarns and/or at least some of said first MD-yarns form top MD-floats on said web contacting side over at least three or at least four adjacent first CD-yarns.

8. The papermaking fabric according to claim 1, wherein some of said first CD-yarns are first CD-plainweave-yarns, and each of said first CD-plainweave-yarns mainly or only form plain weave sequences.

9. The papermaking fabric according to claim 8, wherein some of said first MD-yarns are first MD-float-plainweave-yarns forming top MD-floats and plain weave sequences being alternatingly disposed in said MD-direction, and a plain weave sequence of said first MD-float-plainweave-yarn is located between two consecutive top MD-floats of a first MD-float-plainweave-yarn and vice versa.

10. The papermaking fabric according to claim 9, wherein at least one of said top MD-floats or said plain weave sequences of adjacent first MD-float-plainweave-yarns are offset relative to each other in said MD-direction.

11. The papermaking fabric according to claim 9, wherein some of said first MD-yarns are first MD-plainweave-yarns mainly or only forming plain weave sequences, and a plurality of said first MD-plainweave-yarns are located between two adjacent first MD-float-plainweave-yarns.

12. The papermaking fabric according to claim 9, wherein a plurality of second first MD-yarns are disposed between adjacent first M D-float-plainweave-yarns.

13. The papermaking fabric according to claim 9, wherein at least some top MD-floats from different first MD-float-plainweave-yarns are offset relative to each other in said MD-direction.

14. The papermaking fabric according to claim 9, wherein a plurality of first MD-plainweave-yarns are located between two adjacent first MD-float-plainweave-yarns, and said first MD-plainweave-yarns form a plain weave sequence with at least some of said adjacent first CD-yarns over which one of said two first MD-float-plainweave-yarns form top MD-floats.

15. The papermaking fabric according to claim 9, wherein a plurality of adjacent first MD-plainweave-yarns are located between two adjacent first MD-float-plainweave-yarns forming top MD-floats over a plurality of common adjacent first CD-yarns forming a plain weave sequence with at least some or all common adjacent first CD-yarns.

16. The papermaking fabric according to claim 1, wherein: said first MD-yarns are provided by top MD-yarns and said first CD-yarns are provided by top CD-yarns and by said binder yarns; said second MD-yarns are provided by bottom MD-yarns and said second CD-yarns are provided by bottom CD-yarns; said top MD-yarns only weave with said top CD-yarns and with said binder yarns; said top CD-yarns only weave with said top MD-yarns; said bottom MD-yarns only weave with said bottom CD-yarns and with said binder yarns; said bottom CD-yarns only weave with said bottom MD-yarns; and said binder yarns weave with said top and said bottom MD-yarns.

17. The papermaking fabric according to claim 1, wherein: said binder yarns are disposed in pairs of exchanging binder yarns; each pair of exchanging binder yarns contributes to said weave structure and binds together said two fabric layers causing one of said binders to weave with said top MD-yarns or top CD-yarns and another of said binders to weave with at least one bottom MD-yarn or bottom CD-yarn during a weave path of said two binders of said pair; and said two binders are exchanged at a crossing point causing said other of said binders to weave with said top MD-yarns or top MD-yarns and one of said binders to weave with at least one bottom MD-yarn or bottom CD-yarn after said crossing point.

18. A papermaking fabric extending in a MD-direction and in a CD-direction for a machine for at least one of forming or processing a fibrous web, the papermaking fabric comprising: a top fabric layer, a bottom fabric layer and binder yarns binding said top and bottom fabric layers together; said top fabric layer providing a web contacting side and having a top weave structure formed by interwoven first MD-yarns and first CD-yarns; said bottom fabric layer providing a machine contacting side and having a bottom weave structure formed by interwoven second MD-yarns and second CD-yarns; said top weave structure being repeated in top weave repeats, said top weave structure, per top weave repeat, forming one or more fiber compression area and one or more fiber support area recessed in a thickness direction of the fabric relative to said one or more fiber compression area on said web contacting side and fiber support areas being separated from each other by one or more fiber compression area or vice versa; i. said one or more fiber compression area being formed by a top MD-float or at least two adjacent top MD-floats on said web contacting side or said fiber compression area being formed by a top CD-float or at least two adjacent top CD-floats on said web contacting side, ii. said one or more fiber support area being formed by a plurality of said first MD-yarns interwoven in a plain weave with a plurality said first CD-yarns; and some of said first CD-yarns being first CD-float-yarns, each of said first CD-float-yarns forming a plurality of top CD-floats being consecutively disposed in said CD-direction, and each of said top CD-floats being formed by passing a respective first CD-float-yarn over a plurality of adjacent first MD-yarns.

19. The papermaking fabric according to claim 18, wherein said first CD-float-yarns only form top CD-floats.

20. The papermaking fabric according to claim 18, wherein a plurality of first CD-plainweave-yarns are located between two adjacent first CD-float-yarns, and said first CD-plainweave-yarns form a plain weave sequence with at least some or a majority of one or all of said adjacent first MD-yarns over which said first CD-float-yarns form top CD-floats.

21. The papermaking fabric according to claim 18, wherein: some of said first MD-yarns are first MD-float-plainweave-yarns forming top MD-floats and plain weave sequences being alternatingly disposed in said MD-direction; a plain weave sequence of said first MD-float-plainweave-yarn is located between two consecutive top MD-floats of a first MD-float-plainweave-yarn and vice versa; said first CD-float-yarns provide groups of three adjacent first CD-float-yarns; said first MD-float-plainweave-yarns provide at least a first and a second group of first MD-float-plainweave-yarns; said first MD-float-plainweave-yarns of a first group form first top MD-floats, each passing over said first and said second first CD-float-yarn and all of said first CD-yarns located therebetween; and said first MD-float-plainweave-yarns of a second group form second top MD-floats, each passing over second and third first CD-float-yarns and all of said first CD-yarns located therebetween.

22. The papermaking fabric according to claim 21, wherein: said first MD-floats pass over all of said first CD-yarns located between said first and said second first CD-float-yarn; said first MD-float-plainweave-yarns of said second group weave a plain weave sequence with all of said first CD-yarns located between said first and said second first CD-float-yarn; said second MD-floats pass over all of said first CD-yarns located between said second and said third first CD-float-yarn; and said first MD-float-plainweave-yarns of said first group weave a plain weave sequence with all of said first CD-yarns located between said second and said third first CD-float-yarn.

23. A papermaking fabric extending in a MD-direction and in a CD-direction for a machine for at least one of forming or processing a fibrous web, the papermaking fabric comprising: a top fabric layer, a bottom fabric layer and binder yarns binding said top and bottom fabric layers together; said top fabric layer providing a web contacting side and having a top weave structure formed by interwoven first MD-yarns and first CD-yarns; said bottom fabric layer providing a machine contacting side and having a bottom weave structure formed by interwoven second MD-yarns and second CD-yarns; said top weave structure being repeated in top weave repeats, said top weave structure, per top weave repeat, forming one or more fiber compression area and one or more fiber support area recessed in a thickness direction of the fabric relative to said one or more fiber compression area on said web contacting side and fiber support areas being separated from each other by one or more fiber compression area or vice versa; i. said one or more fiber compression area being formed by a top MD-float or at least two adjacent top MD-floats on said web contacting side or said fiber compression area being formed by a top CD-float or at least two adjacent top CD-floats on said web contacting side, ii. said one or more fiber support area being formed by a plurality of said first MD-yarns interwoven in a plain weave with a plurality said first CD-yarns; said top MD-float or at least two adjacent top MD-floats being said at least two adjacent top MD-floats and including first top MD-floats and second top MD-floats; said first top MD-floats having no offset relative to each other and said second top MD-floats having no offset relative to each other; said first top MD-floats having an offset relative to said second top MD-floats; and a second top MD-float being located between two first top MD-floats being adjacently disposed in said CD-direction, and vice versa.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) The invention is further described by way of a non-limiting example of a papermaker's fabric according to the present invention. It shows

(2) FIG. 1 a photograph onto the web contacting side over several repeat units of the papermaker's fabric,

(3) FIG. 2 the weave paths of the CD-yarns of a repeat unit of the papermaker's fabric from FIG. 1,

(4) FIG. 3 a repeat unit of the papermaking fabric from FIG. 1,

(5) FIG. 4 a repeat unit of the top fabric layer of the papermaker's fabric from FIG. 1 and

(6) FIG. 5 a repeat unit of the bottom fabric layer of the papermaker's fabric from FIG. 1.

DESCRIPTION OF THE INVENTION

(7) The papermaker's fabric 100 as can be seen in FIGS. 1 to 5 extends with its length in a MD-direction and with its width in a CD-direction and comprises a top fabric layer 101 and a bottom fabric layer 102.

(8) The two fabric layers 101, 102 are bound together by binder yarns B3, B4, B7, B8, B11, B12, B15, B15, B19, B20, B23, B24, B27, B28, B31 and B32, in future in short cut named with BS, when all binder yarns together are meant.

(9) The top fabric layer 101 has a top weave structure providing a web contacting side. The top weave structure is formed by interweaving of first MD-yarns with first CD-yarns. In the current embodiment the first MD-yarns are provided by top MD-yarns 1, 3, 5, 6, 8, 10, 11, 13, 15, 16, 18, 20, in future written in short cut OK, when all top MD-yarns together are meant. The first CD-yarns are provided by top CD-yarns O1, O5, O9, O13, O17, O21, O25, O29 and by the binder yarns BS. The top CD-yarns O1, O5, O9, O13, O17, O21, O25, O29 are in future named with OS, when all top CD-yarns together are meant. The binder yarns BS contribute to the top weave structure by continuing the weave structure formed by the top CD-yarns OS and the top MD-yarns OK. The binder yarns further extend in the CD-direction.

(10) As can be seen, the binder yarns BS are arranged in pairs of exchanging binder yarns B3/B4, B7/B8, B11/B12, B15/B16, B19/B20, B23/B24, B27/B28, B31/B32 wherein each pair of exchanging binder yarns contributes to the top weave structure and binds together the two fabric layers 101, 102 such that, during the weave path of the two binders of a pair, the one of the binders e.g. B3 weaves with top MD-yarns 1, 3, 5, 6, 8 while the other of the binders e.g. B4 weaves with a bottom MD-yarn 4, at a crossing point 10 the two binders B3/B4 exchange such that after the crossing point 10 the other of the binders B4 weaves with the top MD-yarns 11, 13, 15, 16, 18 while the one of the binders B3 weaves with a bottom MD-yarn 14. By doing so, the two binders of a binder pair B3/B4 together form a weave path in the top fabric layer like a top CD-yarn. The two binder yarns of a binder yarn pair are thus regarded as a first CD-yarn.

(11) The bottom fabric layer 102 has a bottom weave structure providing a machine contacting side. The bottom weave structure is formed by interweaving of second MD-yarns with second CD-yarns. The second MD-yarns are provided by bottom MD-yarns 2, 4, 7, 9, 12, 14, 17, 19, in future written UK, when all bottom MD-yarns together are meant. The second CD-yarns are provided by bottom CD-yarns U2, U6, U10, U14, U18, U22, U26, U30, which are in future named by US, when all bottom CD-yarns together are meant. Based on that it is clear, that the binder yarns BS don't contribute to the bottom weave structure, because they do not continue the weave structure formed by the bottom CD-yarns US and the bottom MD-yarns UK.

(12) It has to be noted herein, that the top MD-yarns OK only weave with the top CD-yarns OS and with the binder yarns BS, wherein the top CD-yarns OS only weave with the top MD-yarns OK. It has to be further noted, that the bottom MD-yarns UK only weave with the bottom CD-yarns US and with the binder yarns BS, wherein the bottom CD-yarns US only weave with the bottom MD-yarns UK and wherein the binder yarns BS weave with the top MD-yarns OK and with the bottom MD-yarns UK.

(13) The top weave structure is repeated in top weave repeats, wherein per top weave repeat the top weave structure forms several fiber compression areas and several fiber support areas P which are recessed in thickness direction of the fabric relative to the fiber compression areas on the web contacting side.

(14) It has to be noted, that each of the fiber compression areas which mainly extends in CD-direction is formed by one of the top CD-floats FS1, FS2. For example a top CD-float FS1 is formed by the top CD-yarn O29 when passing on the web contacting side over the five adjacent top MD-yarns 6, 8, 10, 11, 13 or by the top CD-yarn O13 when passing on the web contacting side over the five adjacent top MD-yarns 1, 3, 16, 18, 20. As can be seen from FIG. 2, the binder yarns BS do not form top CD-floats on the web contacting side.

(15) It has to be further noted, that each of the fiber compression areas which extend in MD-direction is formed by one of the top CD-floats FK1, FK2. For example a top MD-float FK1 is formed by the top MD-yarn 15 when passing on the web contacting side over the nine adjacent top CD-yarns and binder yarn pairs O29, B31/B32, O1, B3/B4, O5, B7/B8, O9, B11/B12, O13 wherein a top MD-float FK2 is formed by the top MD-yarn 5 when passing on the web contacting side over the nine adjacent top CD-yarns and binder yarn pairs O13, B15/B16, O17, B19/B20, O21, B23/B24, O25, B27/B28, O29. The top MD-yarns 5 and 15 are so called first MD-float-plainweave-yarns which form top MD-floats FK1 or FK2 and plain weave sequences which are alternatingly arranged in MD-direction such that between two consecutive top MD-floats FK1 or between two consecutive top MD-floats FK2 of a first MD-float-plainweave-yarn a plain weave sequence of the first MD-float-plainweave-yarn is located and vice versa. For example the first MD-float-plainweave-yarn 5 forms several consecutive top MD-floats FK2 and between two consecutive top MD-floats FK2 the first MD-float-plainweave-yarn 5 forms a plain weave sequence with the top CD-yarns O1, O5, O9, O13 and the binder yarn pairs B3/B4, B7/B8, B11/B12, B31/B32. Regarding first MD-float-plainweave-yarn 15 it's that this yarn forms several consecutive top MD-floats FK1 and between two consecutive top MD-floats FK1 the first MD-float-plainweave-yarn 15 forms a plain weave sequence with the top CD-yarns O13, O17, O21, O25 and the binder yarn pairs B15/B16, B19/B20, B23/B24, B27/B28.

(16) Further on the top MD-floats FK1 and FK2 formed by the yarns 5 and 15 and the plain weave sequences of the two adjacent first MD-float-plainweave-yarns 5 and 15 are offset relative to each other in MD-direction in such a way that while the first of the two adjacent first MD-float-plainweave-yarns 5 forms a top MD-float FK2 by passing over a plurality of top CD-yarns O13, O17, O21, O25 and the binder yarn pairs B15/B16, B19/B20, B23/B24, B27/B28 the other of the two adjacent first MD-float-plainweave-yarns forms a plain weave sequence with the plurality of top CD-yarns O13, O17, O21, O25 and the binder yarn pairs B15/B16, B19/B20, B23/B24, B27/B28. Further on while the second of the two adjacent first MD-float-plainweave-yarns 15 forms a top MD-float FK1 by passing over a plurality of top CD-yarns O29, O1, O5, O9, O13 and the binder yarn pairs B3/B4, B7/B8, B11/B12, B31/B32 the other of the two adjacent first MD-float-plainweave-yarns forms a plain weave sequence with the plurality of top CD-yarns O29, O1, O5, O9, O13 and the binder yarn pairs B3/B4, B7/B8, B11/B12, B31/B32. The top MD-floats FK1 are herein called in the following first top MD-float FK1 and the top MD-floats FK2 are called in the following second top MD-float FK2.

(17) As can be seen between the two adjacent 5 and 15 first MD-float-plainweave-yarns several first MD-plainweave-yarns 6, 8, 10, 11, 13 on the one side and 16, 18, 20, 1, 3 on the other sidewhen viewed in CD-directionare located which mainly, preferably only, form plain weave sequences.

(18) As can be seen, two adjacent fiber support areas P are separated from each other by the fiber compression areas formed by the top CD-floats FS1, FS2 and the first and second top MD-floats FK1, FK2. As can be seen, the first top MD-floats FK1 of different top MD-yarns 15 are in phase with each other. This means that the different first MD-float-plainweave-yarns 15 all form plainweave sequences with the same first CD-yarns and first MD-floats with other same first CD-yarns. The similar applies the second top MD-floats FK2 of different top MD-yarns 5, which are all in phase with each other, what means that the different first MD-float-plainweave-yarns 5 all form plainweave sequences with the same first CD-yarns and first MD-floats with other same first CD-yarns.

(19) In the present embodiment of the invention all the first top MD-floats FK1 have the same length as well as all the second top MD-floats FK2 have the same length. In addition it can be seen, that all the first top MD-floats FK1 and second top MD-floats FK2 have the same length.

(20) In addition each fiber support P area is formed by several top MD-yarns interwoven in a plain weave with several top CD-yarns. By way of example one of the fiber support areas P is formed by the top MD-yarns 6, 8, 10, 11, 13, 15, 16, 18, 20, 1, 3 interwoven in a plain weave with the top CD-yarns O17, O21, O25 and the binder yarn pairs B15/B16, B19/B20, B23/B24, B27/B28.

(21) As can be especially seen from FIGS. 1 and 4, the top weave structure forms pockets, wherein each pocket has a bottom part and an edge part fully surrounding the bottom part. The bottom part of a pocket is provided by a fiber support area P and the edge part surrounding the bottom part of the pocket is provided by two adjacent first top MD-floats FK1 or by two second adjacent top MD-floats FK2 and by four top CD-floats FS1, FS2. It has to be noted, that always top CD-floats FS1, FS2 which are consecutively arranged in CD-direction are formed by the same top CD-yarn. By way of example some of the top CD-floats FS1 are formed by top CD-yarn O29 when passing over the adjacent top MD-yarns 6, 8, 10, 11 and 13 and the consecutive top CD-float FS2 is formed by the top CD-yarn O29 when passing over the adjacent top MD-yarns 16, 18, 20, 1 and 1. Further another of the top CD-floats FS2 is formed by top CD-yarn O13 when passing over the adjacent top MD-yarns 6, 8, 10, 11 and 13 and the consecutive top CD-float FS1 is formed by the top CD-yarn O13 when passing over the adjacent top MD-yarns 16, 18, 20, 1 and 1.

(22) It has to be noted that the top CD-yarns O13, O29 are first CD-float-yarns, wherein each of the first CD-float-yarns O13, O29 forms several top CD-floats FS1, FS2 which are consecutively arranged in CD-direction, wherein each of the top CD-floats FS1, FS2 is formed by passing of the respective first CD-float-yarn O13, O29 over a plurality of adjacent top MD-yarns. As can be seen the consecutively arranged top CD-floats FS1, FS2 of the same top CD-yarn follow a zigzag line. This is achieved by the fact that all the top CD-floats indicated with FS1 extend from lower left to upper right, whereas all the top CD-floats indicated with FS2 extend from upper left to lower rightas can be seen from FIG. 1and that between two consecutive top CD-floats FS1 of a top CD-yarn O13, O29 a top CD-float FS2 of this top CD-yarn O13, O29 is located and vice versa.

(23) As can be seen between the two adjacent first CD-float-yarns O13, O29 several first CD-plainweave-yarnsprovided by top CD-yarns O1, O5, O9, O17, O21, O25 and binder yarn pairs B3/B4, B7/B8, B11/B12, B15/B16, B19/B20, B23/BB24, B27/B28, B31/B32are located, wherein the first CDplainweave-yarns form a plain weave sequence with the majority of the adjacent top MD-yarns over which the first CD-float-yarns O13, O29 form top CD-floats FS1, FS2.

(24) The six top CD- and MD-floats together are arranged such that the edge part of the pockets has a hexagonal shape and the edge parts of the pockets together form a honey-comb like structure.

(25) The other of the first CD-yarnswhich are either the binder yarn pairs B3/B4, B7/B8, B11/B12, B15/B16, B19/B20, B23/B24, B27/B28, B31/B32 or the top CD-yarns O1, O5, O9, O13, O17, O21, O25, O29 are so called first CD-plainweave-yarns. Each of these first CD-plainweave-yarns mainly, preferably only, form plain weave sequences when interweaving with the top MD-yarns OK, wherein mainly in this case means that that more than 75% of the weave path the respective plainweave first CD-yarn forms a plain weave sequence.

(26) In the embodiment shown in FIGS. 1 to 5, the fiber support area P in average is recessed relative to the fiber compression areas, which are formed by the top MD-floats FK1, FK2 and by the top CD-floats FS1, FS2, by 100 m. The fabric 100 has an air permeability of between 350 and 650 cfm. The mesh count of the top fabric layer 101 can be between 30 to 50 first MD-yarns per cm by 30 to 50 first CD-yarns per cm and the mesh count of the bottom fabric layer 102 can be between 10 to 40 first MD-yarns per cm by 10 to 40 first CD-yarns per cm.