Description of the Prior Art As will be known to those skilled in the art, papermaking machines generally include three sections which are generally referred to as the formation, press and dryer sections. The present invention finds particular application in papermaker's felts which are employed in the press section of a papermaking machine.

Typically, such felts include a supporting base, and a paper carrying or supporting layer fixed to the base. Frequently, the base fabric is a woven fabric which is used as an endless belt.

The woven fabric may be woven as an endless loop and utilized as such so there is no seam or, alternatively, the fabric may be woven to have two ends which are joined at a seam to form the endless loop. Various seams are known in the art, including pin type seams which utilize a joining wire or pintle which is inserted through seam loops at each end of the fabric to render it endless.

One technique of forming a fabric having seam loops is to provide an endless weave wherein loops are formed by weaving stacked weft yarns around a forming wire, as shown in U. S. Patent No. 3,815,645. A common problem associated with this type of loop formation is non-uniform loop alignment, both in the vertical and horizontal axis, when the forming wire is removed.

The misalignment creates a seam that is difficult to mesh.

Figures 1-3 show representative loop misalignments experienced in common prior art endless woven seams. Generally, as a loom weaves the loops in an endless weave, it naturally offsets the returning weft position slightly from its outgoing weft position. Therefore, it is necessary to maintain the weft yarns in a stacked relationship throughout the fabric through the balanced weave of the warp yarns. The last warp yarn 2, however, is generally not balanced by adjacent yarns on each side and therefore, an unbalanced crimp force is applied to the weft yarns in the loop area, as shown by the arrows in Figure 2. As a result, the two weft yarn passes which form each loop are not balanced by warps and the loops tend to be misaligned.

Another problem associated with standard seams is that the seam area has a yarn density twice that of the body since each meshed seam half has a density similar to the body.

Accordingly, it is desired to provide a base fabric having seam loops which are-easier to intermesh and more uniform fabric characteristics in the seam area.

SUMMARY OF THE INVENTION The present invention provides an open ended papermaker's fabric having a system of transverse yarns interwoven with a system of longitudinal yarns. Select longitudinal yarns at each end of the fabric are woven to form seam loops while other longitudinal yarns at each end of the fabric are woven around a yarn of the transverse yarn system to form integral edge tiebacks.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a top plan view of prior art end loops.

Figure 2 is an elevation view of the prior art end loops along the line 2-2 in Figure 1.

Figure 3 is a side elevation view of the prior art end loops along the line 3-3 in Figure 1.

Figure 4 is a schematic perspective view of a portion of the base fabric according to the present invention.

Figure 5 is a side elevation view of a portion of the base fabric taken along line 5-5 in Figure 4.

Figure 6 is a front elevation view of a portion of the base fabric.

Figure 7 is a top plan view of two end portions of the fabric joined together.

DESCRIPTION OF THE PREFERRED EMBODIMENT The preferred embodiment will be described with reference to the drawing figures where like numerals represent like elements throughout.

Referring to Figure 4, it shows a portion of the base fabric 1 in accordance with the present invention. In the preferred embodiment, the base fabric 1 comprises a MD top layer 10-17 and a MD bottom layer 20-27 interwoven with CMD yarns 2-5. The CMD yarns 2-5 are woven in a repeated pattern where each CMD yarn 2-5 passes over, between, under, between with respect to the two layers of MD yarns. Every other MD top layer yarn 10,12,14, 16 is joined with the corresponding MD bottom layer yarn 20,22, 24,26 to form seam loops 30,32,34,36 respectively. The remaining MD top layer yarns 11,13,15,17 are joined with the corresponding MD bottom layer yarns 21,23,25,27 to form integral fabric edge tiebacks 31,33,35,37 respectively. The integral fabric edge tiebacks 31,33,35,37 wrap around the end warp yarn 2, thereby forming an integral fabric edge or tieback inside the loop area.

The seam loops 30,32,34,36 are preferably formed by weaving the respective MD yarns around a forming wire which is removed after weaving. To form the integral tiebacks, the forming wire is shedded to a non-weaving position and the respective MD yarns are woven around the end CMD yarn 2.

Because the integral fabric edge tiebacks balance the crimp force of the end warps 2 and 3, the crimp force applied to the seam loops 30,32,34,36 is reduced. As a result, the seam loops 30,32,34,36 are maintained in better vertical and horizontal alignment, as shown in Figures 5 and 6.

As shown in Figure 7, the opposite ends 40,40'of the fabric are formed such that the seam loops 30,32,34,36 of one end complement the integral fabric edge loops 31', 33', 35', 37'

of the opposite end and vice versa. The vertical and horizontal alignment of the seam loops 30,32,34,36 and 30', 32', 34', 36' allows the respective ends 40,40'of the fabric to be intermeshed more efficiently and the pintle inserted more easily.

Another advantage of the preferred configuration is that the machine direction yarn density in the seam zone is similar to that of the body. Since the seam loops at one end align with the edge tiebacks of the other end, and vice versa, the number of seam loops aligned in the seam zone when the ends of the fabric are joined is essentially equal to the number of machine direction yarns across the entire fabric. This produces a more uniform permeability and flow profile in the fabric seam area.

As shown in Figure 7, batt material 50 may be applied to one or both surfaces of the base fabric 1 as desired.

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