Fabric for a web-producing machine and such a machine with a corresponding fabric

Abstract

A fabric for a web-producing machine, such as a papermaker's machine for producing paper, tissue or board, contains a machine-side and a paper-side. The fabric further contains MD-yarns and CD-yarns interwoven with each other in a predetermined repeat pattern. The MD-yarns 12 have a non-circular cross-section, and a width-to-height aspect ratio of the MD-yarns 12 is greater than 10:1, preferably at least 11:1. Furthermore, a web-producing machine, such as a papermaker's machine for producing paper, tissue or board, contains a fabric of the above described type, where the fabric is preferably applied in a dryer section of the web-producing machine.

Claims

1. A fabric for a web-producing machine, the fabric being a double-layer fabric comprising: a machine-side; a paper-side; and an upper layer and a lower layer forming the double-layer fabric; MD-yarns having a non-circular cross-section, wherein said MD-yarns, which have the non-circular cross-section, include upper layer MD-yarns in said upper layer and lower layer MD-yarns in said lower layer, wherein a width-to-height aspect ratio of said MD-yarns is greater than 10:1; and CD-yarns interwoven with said MD-yarns in a predetermined repeat pattern resulting in the fabric being a dryer fabric of a papermaker's machine for producing paper, tissue or board; said upper layer MD-yarns interlacing with said CD-yarns; and said lower layer MD-yarns interlacing with said CD-yarns; wherein said upper layer MD-yarns do not intersect with said lower layer MD-yarns; and wherein the fabric includes at least two groups of said CD-yarns with differently dimensioned cross-sections.

2. The fabric according to claim 1, wherein the width-to-height aspect ratio of said MD-yarns is not greater than 15:1.

3. The fabric according to claim 1, wherein a width of said MD-yarns is between 2.0 mm and 2.4 mm.

4. The fabric according to claim 1, wherein some of said CD yarns are disposed along their complete path between said upper layer MD-yarns and said lower layer MD-yarns, thus, not being visible from said paper-side and/or said machine-side of the fabric, whereas remaining said CD-yarns are at least partly visible from said paper-side and/or said machine-side of the fabric.

5. The fabric according to claim 1, wherein said MD-yarns and/or said CD-yarns are made of monofilaments.

6. The fabric according to claim 1, wherein said MD-yarns have a flattened shape with a flat upper surface side and a flat lower surface side, wherein said flat upper surface side and said flat lower surface side extend substantially parallel to each other.

7. The fabric according to claim 1, wherein said MD-yarns have an octagonal cross-section.

8. The fabric according to claim 1, wherein: said CD-yarns have a circular cross-section; and a diameter of said CD-yarns is not smaller than 0.5 mm and/or not larger than 1.0 mm.

9. The fabric according to claim 1, wherein the fabric contains at least a first group of said CD-yarns with a circular cross-section of a first diameter and a second group of said CD-yarns with a circular cross-section of a second diameter, the second diameter being greater than the first diameter, wherein a ratio of the second diameter to the first diameter is between 2:1 and 1:1.

10. The fabric according to claim 1, wherein the fabric is flat woven and contains a seam area for making the fabric endless, wherein said seam area has seam loops formed by said MD-yarns for implementing a pintle joint.

11. The fabric according to claim 1, wherein the width-to-height aspect ratio of said MD-yarns is at least 11:1.

12. The fabric according to claim 2, wherein the width-to-height aspect ratio of said MD-yarns is not greater than 12:1.

13. The fabric according to claim 3, wherein the width of said MD-yarns is 2.2 mm, and/or the height of said MD-yarns is 0.2 mm.

14. The fabric according to claim 5, wherein said monofilaments are selected from the group of a polymeric material, a PET, a PPS, a PCTA and a POK.

15. The fabric according to claim 9, wherein the ratio of the second diameter to the first diameter is 3:2.

16. The fabric according to claim 1, wherein a height of said MD-yarns is between 0.1 mm and 0.3 mm.

17. A web-producing machine, comprising: a dryer section; and a double layer fabric including: a machine-side, a paper-side, and an upper layer and a lower layer forming the double-layer fabric, MD-yarns having a non-circular cross-section, wherein said MD-yarns, which have the non-circular cross-section, include upper layer MD-yarns in said upper layer and lower layer MD-yarns in said lower layer, wherein a width-to-height aspect ratio of said MD-yarns is greater than 10:1, and CD-yarns interwoven with said MD-yarns in a predetermined repeat pattern resulting in the fabric being a dryer fabric of a papermaker's machine for producing paper, tissue or board; said upper layer MD-yarns interlacing with said CD-yarns, and said lower layer MD-yarns interlacing with said CD-yarns, wherein said upper layer MD-yarns do not intersect with said lower layer MD-yarns; wherein the fabric includes at least two groups of said CD-yarns with differently dimensioned cross-sections; and wherein the fabric is applied in said dryer section of the web-producing machine.

18. A fabric for a web-producing machine, the fabric comprising: a machine-side; a paper-side; MD-yarns having a non-circular cross-section, wherein a width-to-height aspect ratio of said MD-yarns being greater than 10:1; and CD-yarns interwoven with said MD-yarns in a predetermined repeat pattern resulting in the fabric being a dryer fabric of a papermaker's machine for producing paper, tissue or board; wherein the fabric contains at least two groups of said CD-yarns with differently dimensioned cross-sections; wherein the fabric contains at least a first group of said CD-yarns with a circular cross-section of a first diameter and a second group of said CD-yarns with a circular cross-section of a second diameter, the second diameter being greater than the first diameter, wherein a ratio of the second diameter to the first diameter is between 2:1 and 1:1; and wherein said CD-yarns of said second group are not visible from said paper-side and/or said machine-side of the fabric, whereas said CD-yarns of said first group are at least partly visible from said paper-side and/or said machine-side of the fabric.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) FIG. 1 shows a paper-side portion of an exemplary embodiment of the fabric according to the present invention;

(2) FIG. 2 shows a cross-sectional view of the fabric along line II-II in FIG. 1;

(3) FIG. 3 shows a cross-sectional view of the fabric along line III-III in FIG. 1,

(4) FIG. 4 shows an enlarged cross-sectional view of an MD-yarn of the fabric;

(5) FIG. 5 shows a similar view on a paper-side portion of the fabric as FIG. 1 but comprising a seam area of that fabric; and

(6) FIG. 6 shows a cross-sectional view of the fabric along line VI-VI in FIG. 5.

DETAILED DESCRIPTION OF THE INVENTION

(7) FIG. 1 shows a portion of a fabric 10 according to the present invention wherein the portion is seen from the paper-side of the fabric 10. However, since the fabric 10 has a substantially symmetrical weave pattern, FIG. 1 may equally refer to the machine-side thereof. The fabric preferably is a dryer fabric to be used as such in the dryer section of a machine for producing a fibrous web. The shown portion of the fabric 10 comprises nine MD-yarns 12 extending in machine direction MD of the fabric 10. All MD-yarns 12 have substantially the same cross-sectional shape that is shown in the enlarged view of FIG. 4, wherein in this exemplary embodiment the width-to-height ratio of the cross-sectional shape is about 11:1. For example the width w of the MD-yarn might be about 2.20 mm and the height h of the MD-yarn might be about only 0.20 mm. The cross-sectional shape of the MD-yarn 12 is octagonal, i.e. it is almost rectangular but with the edges cut off. The MD-yarn 12 has a substantially flat upper surface side 12a and a substantially flat lower surface side 12b, wherein the upper surface side 12a and the lower surface side 12b extend substantially parallel to each other. The MD-yarn 12 is a monofilament made from a polymeric material, such as PET, PPS, PCTA and/or POK, preferably by extrusion.

(8) The MD-yarns 12 are interwoven with a plurality of CD-yarns 14. The CD-yarns 14 all have a substantially circular cross-section. However, the fabric 10 comprises at least two groups of CD-yarns 14 with differently dimensioned cross-sections. In FIG. 1 only three yarns of a first group of first CD-yarns 14a having a relatively small diameter are shown. In the view of FIG. 1 the weaving pattern of the MD-yarns 12 and the first CD-yarns 14a resembles a plain weave structure. As shown in FIGS. 2 and 3 the fabric 10 further comprises yarns of a second group of second CD-yarns 14b having a relatively large diameter. The second CD-yarns 14b are not visible from the paper-side of the fabric 10 (as shown in FIG. 1) nor from the machine-side. Instead, as best seen in FIG. 3, the second CD-yarns 14b extend straight in cross-machine direction CD of the fabric 10 between an upper layer UL of MD-yarns 12 and a lower layer LL of MD-yarns 12. The second CD-yarns 14b have no or hardly any crimp. The upper layer UL of MD-yarns 12 and the lower layer LL of MD-yarns do not intersect each other.

(9) Finally, FIGS. 5 and 6 show a seam area of the fabric 10. Since the fabric 10 is flat woven, its longitudinal ends have to be joined together to make the fabric 10 endless. FIG. 5 shows a similar view on the paper-side of the fabric 10 as FIG. 1 and FIG. 6 shows a cross-sectional view along line VI-VI in FIG. 5. In the present exemplary embodiment the seam is implemented via a pintle 16. Here, the pintle 16 comprises three monofilament yarns extending in cross-machine direction CD of the fabric 10. The pintle 16 passes through a series of seam loops 18 formed by the MD-yarns 12. The MD-yarns 12 of the upper layer UL is woven back into the structure of the fabric 10, thus, integrally forming also the lower layer LL of the fabric 10 at least in the seam area. At each lateral end of the fabric 10 the MD-yarns 12 alternately form seaming loops 18 and binder loops 20. The seaming loops 18 of both longitudinal end of the fabric 10 are interdigitated in the web-producing machine to provide a closed channel for the pintle 16.

(10) Between the seaming loop 18 of one longitudinal end of the fabric 10 and the opposite binder loop 20 of the other longitudinal end of the fabric 10 there may be provided a small gap 22, as indicated in FIG. 1 by a black rectangle.

(11) Furthermore, in the seam area the fabric 10 may comprise third CD-yarns 14c for stabilizing the seam area. As shown in FIG. 6, four such third CD-yarns 14c are provided, two at each longitudinal end of the fabric 10. In the present exemplary embodiment the third CD-yarns 14c have a circular cross-section with substantially the same diameter as the circular cross-section of the first CD-yarns 14a. However, likewise the second CD-yarns 14b, the third CD-yarns 14c extend straight in cross-machine direction CD of the fabric 10 between the upper layer UL of MD-yarns 12 and the lower layer LL of MD-yarns 12. The first CD-yarns 14a and the third CD-yarns 14c may have for example a circular cross-section with a diameter of about 0.6 mm, whereas the second CD-yarns 14b may have for example a circular cross-section with a diameter of about 0.9 mm.

LIST OF REFERENCE SIGNS

(12) 10 fabric 12 MD-yarn 12a upper surface side 12b lower surface side 14 CD-yarn 14a first CD-yarn 14b second CD-yarn 14c third CD-yarn 16 pintle 18 seam loops 20 binder loops 22 gap CD cross-machine direction h height LL lower layer MD machine direction UL upper layer w width