Structured fabric with discrete elements

Abstract

A woven fabric for a fiber web producing machine has a defined machine direction, a cross machine direction, a web facing side, and a machine side. The web facing side is formed by MD yarns that extend substantially in the machine direction and by CD yarns extending substantially in the cross machine direction of the woven fabric. The MD yarns and CD yarns are interwoven with each other and the woven fabric is configured to structure the fiber web produced on the woven fabric. A plurality of adjacent long flotations of MD yarns on the web facing side form together a discrete element that is raised on the web facing side for allowing the woven fabric to structure the fiber web. The term long flotation means that the MD yarn passes over at least six adjacent CD yarns on the web facing side of the woven fabric.

Claims

1. A woven fabric for use in a machine for producing a fiber web, the woven fabric having a machine direction, a cross machine direction, a web facing side, and a machine side, the woven fabric comprising: mutually interwoven machine direction (MD) yarns and cross direction (CD) yarns forming the web facing side with said MD yarns extending substantially in a machine direction of the woven fabric and said CD yarns extending substantially in a cross machine direction of the woven fabric; wherein the woven fabric is configured to structure the fiber web produced on the woven fabric; a plurality of more than two mutually adjacent long flotations of mutually adjacent said MD yarns on the web facing side together forming a discrete element that is raised on the web facing side of the woven fabric for enabling the woven fabric to structure the fiber web, with long flotations being formed by an MD yarn passing over at least six mutually adjacent CD yarns on the web facing side of the woven fabric.

2. The woven fabric according to claim 1, wherein the fiber web is a tissue fiber web.

3. The woven fabric according to claim 1, wherein each long flotation of said plurality of more than two adjacent long flotations of MD yarns on the web facing side that together form the discrete element floats over at least eight adjacent CD yarns on the web facing side of the woven fabric.

4. The woven fabric according to claim 1, wherein each long flotation of said plurality of more than two adjacent long flotations of MD yarns on the web facing side that together form the discrete element floats over not more than eleven adjacent CD yarns on the web facing side of the woven fabric.

5. The woven fabric according to claim 1, wherein each long flotation of said plurality of more than two adjacent long flotations of MD yarns on the web facing side that together form the discrete element floats over not more than nine adjacent CD yarns on the web facing side of the woven fabric.

6. The woven fabric according to claim 1, wherein the discrete element is substantially diamond shaped.

7. The woven fabric according to claim 6, wherein the substantially diamond shaped discrete element has a larger extension in machine direction compared to the cross machine direction of the woven fabric.

8. The woven fabric according to claim 1, wherein the discrete element is one of a plurality of discrete elements on the web facing side of the woven fabric.

9. The woven fabric according to claim 8, wherein said plurality of discrete elements are arranged in a regular pattern on the web facing side of the woven fabric.

10. The woven fabric according to claim 8, wherein said plurality of discrete elements are arranged in columns extending in the machine direction and in rows extending in the cross machine direction, and wherein the discrete elements of a column are offset in machine direction to the discrete elements of an adjacent column of discrete elements.

11. The woven fabric according to claim 10, wherein the offset is one half a length of said discrete element in the machine direction, thus forming valleys between said discrete elements which valleys extend in straight lines that form an angle to the machine direction of the woven fabric.

12. The woven fabric according to claim 1, wherein each long flotation of said plurality of more than two adjacent long flotations of MD yarns on the web facing side that together form the discrete element overlap a respectively adjacent long flotation by at least two CD yarns.

13. The woven fabric according to claim 1, wherein said discrete element is formed on the web facing side by long flotations of five adjacent MD yarns.

14. The woven fabric according to claim 1, wherein said CD yarns forming the web facing side of the woven fabric have two different diameters, with a first diameter being smaller than a second diameter.

15. The woven fabric according to claim 14, wherein said CD yarns that pass over an MD yarn on the web facing side at a point where the long flotation of said MD yarn ends has the first diameter.

16. The woven fabric according to claim 1, wherein a middle of said discrete element is free of long flotations.

17. The woven fabric according to claim 1, wherein said mutually adjacent long flotations are offset from one another in the machine direction by an offset of two or more mutually adjacent CD yarns.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1A shows a portion having a plurality of raised discrete elements on the paper side of a woven fabric according to a first embodiment of the present invention;

(2) FIG. 1B shows an enlarged view of one raised discrete element from the first embodiment of FIG. 1A;

(3) FIG. 1C shows a weaving card for the fabric shown in FIG. 1A, wherein several raised discrete elements are outlined;

(4) FIG. 1D shows the weaving card of FIG. 1C, wherein only one raised discrete element is outlined and the corresponding long flotations of MD yarns on the paper side are highlighted;

(5) FIG. 2A shows a portion having a plurality of raised discrete elements on the paper side of a woven fabric according to a second embodiment of the present invention;

(6) FIG. 2B shows an enlarged view of one raised discrete element from the second embodiment of FIG. 2A;

(7) FIG. 3A shows a portion having a plurality of raised discrete elements on the paper side of a woven fabric according to a third embodiment of the present invention;

(8) FIG. 3B shows an enlarged view of one raised discrete element from the third embodiment of FIG. 3A;

(9) FIG. 4A shows a portion having a plurality of raised discrete elements on the paper side of a woven fabric according to a fourth embodiment of the present invention;

(10) FIG. 4B shows an enlarged view of one raised discrete element from the fourth embodiment of FIG. 4A.

DETAILED DESCRIPTION OF THE INVENTION

(11) Referring now to the figures of the drawing in detail and first, in particular, to FIGS. 1A to 1D thereof, there is shown a first embodiment of the present invention. FIG. 1A shows a portion of the paper side of a woven fabric 10 according to the first embodiment of the present invention. As can be seen from this figure, a plurality of substantially diamond shaped raised discrete elements 12 is formed on the paper side of the woven fabric 10. Between these raised discrete elements 12 valleys 14 are formed. The valleys 14 extend in straight lines over the paper side of the woven fabric 10, wherein the straight lines form an angle between 0 and 90 with the machine direction MD and the straight lines of the valleys 14 intersect each other. In FIG. 1A, for the sake of simplicity, only one discrete element 12 is outlined and only the intersecting straight lines of two valleys 14 are emphasized. The raised elements 12 have substantially all the same aspect. Their extension in machine direction MD is larger than their extension in cross machine direction CD, preferably at least twice as large as their extension in cross machine direction CD.

(12) Furthermore, the discrete elements 12 are arranged on the paper side of the woven fabric 10 in a substantially regular pattern. In this embodiment the discrete elements 12 are arranged in rows 16 that extend in cross machine direction CD and in columns 18 that extend in machine direction MD. The discrete elements 12 of one column 18 are arranged with an offset of about half the extension in machine direction MD of the discrete elements 12 with respect to the discrete elements 12 of an adjacent column 18. Thus, adjacent rows 16 overlap each other. In contrast to this, adjacent columns 18 do not overlap each other. The width of each column 18 substantially corresponds to the width of the discrete elements 12, i.e., to the extension of the discrete elements 12 in cross machine direction CD. Adjacent discrete elements 12 of one row 16 of discrete elements 12 have only a slight offset in machine direction MD relative to each other. This slight offset corresponds only to one CD yarn as may be best seen in the weaving card shown in FIG. 1C. The weaving card of FIG. 1C illustrates 20 MD yarns and 28 CD yarns. Whenever the number of an MD yarn is provided in the weaving card this means that the corresponding MD yarns floats at this particular position over the corresponding CD yarn on the paper side of the woven fabric 10.

(13) FIG. 1B shows an enlarged view of one single discrete element 12 from FIG. 1A. As can be seen from this enlarged view, the discrete element 12 is formed by long flotations (that are highlighted in FIG. 1D) of five adjacent MD yarns that at least partially overlap each other in machine direction MD. The discrete element 12 of FIG. 1B may correspond to the discrete element 12 outlined in the weaving card of FIG. 1D. A first MD yarn, namely MD yarn number 12 according to the weaving card contributes to the discrete element 12 with only one long flotation passing over the CD yarns numbers 9-17 and thus having a length of nine. A second MD yarn, namely MD yarn number 13 contributes to the discrete element 12 with two long flotations passing over the CD yarns number 5-12 and 14-21, respectively, and thus each having a length of eight. A third MD yarn, namely MD yarn number 14 in this embodiment even contributes to the discrete element 12 with three long flotations passing over the CD yarns number 1-8, 10-18 and 20-27, respectively, thus having a length of eight, nine and eight, respectively. The third MD yarn is the central MD yarn of the discrete element 12. A fourth MD yarn, namely MD yarn number 15 contributes to the discrete element 12 with two long flotations passing over the CD yarns number 6-13 and 15-22, respectively, thus each having a length of eight. A fifth MD yarn, namely MD yarn number 16 contributes to the discrete element 12 with only one long flotation passing over the CD yarns number 9-17, thus having a length of nine. As may have been noticed, the discrete element is not fully symmetrical with respect to its central MD yarn (i.e., the third MD yarn with number 14) because the long flotations formed by the second MD yarn (i.e., the MD yarn having the number 13) are slightly offset in machine direction MD with respect to the flotations formed by the fourth MD yarn (i.e., the MD yarn having the number 15).

(14) A second embodiment of the woven fabric 10 according to the present invention will be described in the following with reference to FIGS. 2A and 2B. These figures substantially correspond to FIGS. 1A and 1B of the first embodiment, respectively. In fact, both embodiments are very similar to each other, and the weaving card shown in FIGS. 1C and 1D also applies to the second embodiment of FIGS. 2A and 2B. The same reference signs have been chosen for both embodiments and in the following only the differences between these two embodiments will be discussed. For the rest, reference is made to the description of the first embodiment above.

(15) The only difference between the second embodiment and the first embodiment is that in the second embodiment some CD yarns have a smaller diameter while the remaining CD yarns have a larger diameter. More precisely, the CD yarns that pass over an MD yarn on the web facing side at a point where the long flotation of the MD yarn ends have the smaller diameter. All other CD yarns to which this does not apply have the larger diameter. With respect to the weaving card shown in FIG. 1D, these particular points can be easily identified as blank fields at the corresponding ends of the highlighted flotations of the five MD yarns forming the discrete element 12. Thus, in this weaving card the CD yarns with numbers 4, 5, 9, 10, 13, 14, 18, 19, 22, 23 and 28 have the smaller diameter. Also the CD yarn with number 27 has the smaller diameter since the flotation of MD yarn with number 4 of another discrete element 12 ends there due to the above-mentioned slight offset (see FIG. 1C). As may have been noticed, the CD yarns with the smaller diameter always form pairs of adjacent CD yarns.

(16) A third embodiment of the woven fabric 10 according to the present invention will be described in the following with reference to FIGS. 3A and 3B. These figures substantially correspond to FIGS. 1A and 1B of the first embodiment, respectively. In fact, both embodiments are similar to each other. Thus, the same reference signs have been chosen for both embodiments and in the following only the differences between these embodiments will be discussed. For the rest, reference is made to the description of the first embodiment above.

(17) The only difference between the third embodiment and the first embodiment is that in the third embodiment the central MD yarn (i.e., the third MD yarn with number 14 according to the weaving card of FIG. 1D) only contributes to the discrete element 12 with two long flotations instead of three long flotations as in the first embodiment. These two long flotations pass over the CD yarns number 1-8 and 20-27, respectively, thus having each a length of eight. In the middle of the raised element 12, the central MD yarn only forms short flotations on the web facing side having the length of two or three. Thus, the middle of the discrete element 12 is free of a long flotation, so that the discrete element forms a small pocket in its center.

(18) A fourth embodiment of the woven fabric 10 according to the present invention is shown in FIGS. 4A and 4B. These figures substantially correspond to FIGS. 2A and 2B of the second embodiment, respectively, as well as to FIGS. 3A and 3B of the third embodiment, respectively. In fact, the fourth embodiment represents a mixture of the second and the third embodiment. It comprises the CD yarns of smaller diameter according to the second embodiment and the central MD yarn only contributes to the discrete element 12 with two long flotations according to the third embodiment. To avoid redundancies, reference is made to the description of the second and third embodiments above.

(19) The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention: 10 woven fabric 12 discrete element 14 valley 16 row (of discrete elements) 18 column (of discrete elements) MD machine direction CD cross machine direction