Multi-layer warp bound papermaker's forming fabrics

1. A forming fabric comprising a series of repeat units, each of the repeat units comprising:

a set of binding warp yarns including a first set of binding warp yarns and a second set of binding warp yarns, wherein a binding warp yarn from the first set is paired with a binding warp yarn from the second set;

a set of spring warp yarns, wherein each spring warp yarn is arranged between a first pair of binding warp yarns and a second pair of binding warp yarns;

a set of top weft yarns including odd and even top weft yarns, wherein the top weft yarns interweave with the binding warp yarns and the spring warp yarns to form a top fabric layer, wherein the spring warp yarns interweave only with the top weft yarns, and wherein a first pair of binding warp yarns is offset to a second pair of binding warp yarns alternately by at least two top weft yarns and then by at least four top weft yarns;

a set of bottom weft yarns; and

a set of bottom warp yarns, the bottom warp yarns interwoven with the bottom weft yarns to form a bottom fabric layer;

wherein the binding warp yarns from the first and second set and the spring warp yarns interweave with the top weft yarns to relatively form a plain weave pattern in defined zones such that (a) the first set of binding warp yarns only pass over odd top weft yarns; (b) the second set of binding warp yarns only pass over even top weft yarns; (c) the first binding warp yarn in the pair is offset from the second binding warp yarn in the pair by at least three top weft yarns to create an overlap in the warp path of the pair of binding warp yarns; and (d) each spring warp yarn passes over even and odd top weft yarns;

wherein the binding warp yarns from the first and second set and the bottom warp yarn interweave with the bottom weft yarns,

wherein the binding warp yarns from the first and second set and the bottom warp yarn interweave with the bottom weft yarns such that: (a) each bottom warp yarn forms a plurality of knuckles along the bottom fabric layer; (b) each binding warp yarn from the first set interweaves under a bottom weft yarn beside a bottom warp yarn to form a respective first knuckle of the plurality of knuckles; and (c) each binding warp yarn from the second set interweaves under a bottom weft yarn beside a bottom warp yarn to form a respective second knuckle of the plurality of knuckles such that adjacent first and second knuckles form a plurality of double knuckles along the bottom fabric layer.

2. The forming fabric of claim 1 , wherein each spring warp yarn includes a segment in which the spring warp yarn interweaves with the top weft yarns in an over 1/under 1/over 1/under 4/over 1/under 1/over 1/under 2 sequence.

3. The forming fabric of claim 1 , wherein each spring warp yarn includes a segment in which the spring warp yarn swings toward a first pair of binding warp yarns to push the first pair of binding warp yarns together and a segment in which the spring warp yarn swings toward a second adjacent pair of binding warp yarns to push the second pair of binding warp yarns together.

4. The forming fabric of claim 1 , wherein each binding warp yarns from the first and second set includes a segment in which each binding warp yarn interweaves with the top weft yarns in an over 1/under 1/over 1/under 5/over 1/under 1/over 1/under 1 sequence.

5. The forming fabric of claim 1 , wherein the repeat units of the top fabric layer comprises 4 binding warp yarns from the first set, 4 binding warp yarns from the second set, 4 spring warp yarns, and 12 top weft yarns, and wherein the repeat units of the bottom fabric layer comprises 4 bottom warp yarns, 8 binding warp yarns, and 8 bottom weft yarns.

6. The forming fabric of claim 1 , wherein an arrangement of double knuckles along the bottom fabric layer follows a zigzag pattern.

7. The forming fabric of claim 6 , wherein the zigzag pattern comprises a first set of double knuckles formed in a first diagonal line and a second set of double knuckles formed in a second diagonal line, each set of double knuckles comprising four double knuckles, the second diagonal line of double knuckles being offset from the first diagonal line of double knuckles.

8. The forming fabric of claim 7 , wherein each diagonal line comprises 4 double knuckles, each double knuckle formed by a bottom warp yarn and a binding warp yarn from the first or second set.

9. The forming fabric of claim 6 , wherein the bottom warp yarn forming part of the first double knuckle in the second diagonal line forms part of the third double knuckle in the first diagonal line, and the bottom warp yarn forming part of the second double knuckle in the second diagonal line forms part of the fourth double knuckle in the first diagonal line.

10. The forming fabric of claim 1 , wherein the top fabric layer comprises a series of weft path repeat units comprising at least one first weft path, at least one second weft path, and at least one third weft path, wherein

(a) the first weft path includes a segment in which a top weft yarn interweaves with the binding and spring warp yarns in an over 3/under 1/over 2/under 1/over 2/under 1/over 1/under 1 sequence;

(b) the second weft path includes a segment in which a top weft yarn interweaves with the binding and spring warp yarns in an over 3/under 1/over 2/under 1/over 1/under 1/over 2/under 1 sequence; and

(c) the third weft path includes a segment in which a top weft yarn interweaves with the binding and spring warp yarns in an over 3/under 1/over 1/under 1/over 2/under 1/over 2/under 1 sequence.

11. The forming fabric of claim 10 , wherein the weft path repeat unit includes a segment of weft paths arranged as follows: the first weft path, the second weft path, the first weft path, the third weft path, the second weft path, and the third weft path.

12. The forming fabric of claim 10 , wherein the weft path repeat units create a top fabric layer that is devoid of visible diagonal lines.

13. The forming fabric of claim 10 , wherein the weft path repeat unit creates a paisley pattern shaped plain weave zone in the top fabric layer.

14. The forming fabric of claim 10 , wherein consecutive weft path repeat units create mirrored paisley pattern shaped plain weave zone in the top fabric layer.

15. The forming fabric of claim 13 , wherein the paisley pattern shaped plain weave zone formed in the top fabric layer is aligned between the zigzag lines of double knuckles formed in the bottom fabric layer.

16. The forming fabric of claim 10 , wherein the segment of the first, second, and third weft paths that passes over 3 warp yarns in the top fabric layer is aligned in the middle and between the two double knuckles in machine direction formed in the bottom fabric layer.

17. The forming fabric of claim 7 , wherein the bottom weft yarns to the right of the first double knuckle in a diagonal has an asymmetrical form creating a broader contact area than the same bottom weft yarn to the left of the first double knuckle in an adjacent diagonal, and wherein the bottom weft yarns to the left of the fourth double knuckle in the diagonal has an asymmetrical form creating a broader contact area than the same bottom weft yarn to the right of the fourth double knuckle in the adjacent diagonal.

18. The forming fabric of claim 17 , wherein the bottom weft yarns to the left and right of the second and third double knuckles in the diagonal have a symmetrical form with substantially equal contact areas.

19. The forming fabric of claim 1 , wherein the forming fabric has a weft yarn ratio of three top weft yarns to two bottom weft yarn (3:2).

20. A forming fabric comprising a series of repeat units, each of the repeat units comprising:

a set of binding warp yarns including a first set of binding warp yarns and a second set of binding warp yarns, wherein a binding warp yarn from the first set is paired with a binding warp yarn from the second set;

a set of spring warp yarns, wherein each spring warp yarn is arranged between a first pair of binding warp yarns and a second pair of binding warp yarns;

a set of top weft yarns including odd and even top weft yarns, wherein the top weft yarns interweave with the binding warp yarns and the spring warp yarns to form a top fabric layer, wherein the spring warp yarns interweave only with the top weft yarns, and wherein a first pair of binding warp yarns is offset to a second pair of binding warp yarns alternately by at least two top weft yarns and then by at least four top weft yarns;

a set of bottom weft yarns; and

a set of bottom warp yarns, the bottom warp yarns interwoven with the bottom weft yarns to form a bottom fabric layer;

wherein the binding warp yarns from the first and second set and the spring warp yarns interweave with the top weft yarns to relatively form a plain weave pattern in defined zones such that (a) the first set of binding warp yarns only pass over odd top weft yarns; (b) the second set of binding warp yarns only pass over even top weft yarns; (c) the first binding warp yarn in the pair is offset from the second binding warp yarn in the pair by at least three top weft yarns to create an overlap in the warp path of the pair of binding warp yarns; and (d) each spring warp yarn passes over even and odd top weft yarns;

wherein the binding warp yarns from the first and second set and the bottom warp yarn interweave with the bottom weft yarns,

wherein each spring warp yarn includes a segment in which the spring warp yarn swings toward a first pair of binding warp yarns to push the first pair of binding warp yarns together and a segment in which the spring warp yarn swings toward a second adjacent pair of binding warp yarns to push the second pair of binding warp yarns together.