Papermakers Fabrics

Abstract

This invention relates to paper machine clothing, and more particularly to a woven forming medium, the machine direction yarns of which have crimps which undulate in the cross-machine direction, and to a method for producing same.

Parent Case Text

This is a continuation of copending patent application Ser. No. 831,899, filed June 10, 1969. "This copending application has been permitted to become abandoned in favor of the present case."

Description

BACKGROUND OF THE INVENTION

In the typical fourdrinier papermaking machine, an aqueous suspension of fibers, called the "furnish" is flowed onto a traveling fourdrinier wire or hydrofoils, medium, generally a woven belt of wire and/or synthetic material, to form a continuous sheet of paper or paper-like material. In this connection, the expression "paper or paper-like material" is used in a broad or generic sense and is intended to include such items as paper, kraft, board, pulp, asbestos sheet and other similar sheet-like structures. As the "furnish" travels along on the fourdrinier wire, much of its water content is removed by draining and a somewhat self-supporting continuous web is formed. This water removal is enhanced by the use of such well-known devices as hydrolfoils, table rolls, and/or suction boxes.

After leaving the forming section at the couch roll, the somewhat self-supporting web is transferred to a press section in the machine where still more of its water content is removed by passing it through a series of pressure nips formed by cooperating press rolls, these press rolls also serving to compact the web as well. The paper web is then transferred to a dryer section in the machine where it is passed about and held in heat transfer relationship with a series of heated, cylindrical rolls by which still further amounts of water are removed by evaporation. Finally, the paper web is passed through a series of calender rolls where loose fiber ends are laid down and the paper web is provided with a smooth finish, after which the paper web is collected on a suitable reel.

The present invention relates to forming media. A forming medium is designed to be (1) fluid permeable so that large amounts of water may be drained therethrough from the deposited furnish, and yet not so open as to permit large numbers of deposited fibers to pass therethrough and thus interfere with the formation of the paper web, produce a sheet of poorer printing quality and result in a high loss of constituent fibers in the form of "white water," (2) flexible in order to avoid premature failure thereof due to fatigue, (3) smooth and uniform in order to prevent marking or undue marring of the paper surface, (4) dimensionally stable in order to prevent "shoving" or dimensional changes which can vary the permeability of the medium, and therefore its drainage and other characteristics as well as the characteristics of the paper formed thereon from place to place, and (5) resistant to wear and corrosion in the aqueous environment of the forming section.

Forming media conventionally have been woven wire structures made from materials such as phosphor bronze, bronze, stainless steel, brass or suitable combinations thereof. Such forming "wires" are woven flat in a plain, twill, satin or other suitable weave pattern. Subsequent to the weaving of the "wire," both ends thereof are joined to form an endless belt-like structure as by welding the two ends of the "wire" together. Recent developments in the papermaking field have shown that fabrics of superior suitability for use as forming medium may be woven entirely or in part of synthetic materials. Nylon, a polyamide fiber, has been found to be suitable. Other examples of suitable materials are polyesters, such as Dacron, or acrylic fibers such as Orlon, dynel and Acrilan or copolymers, such as saran. The warp and weft yarns may be of the same or different constituent materials and/or constructions, and may be in the form of monofilament or multifilament yarns, or they may be yarns made up of suitable strands or plies which are in turn formed from staple fiber. Such fabrics may be woven flat and made endless by, for example, hand weaving the two ends of the fabric together, or they may be woven endless, as, for example, the fabric described and claim in U.S. Pat. No. 2,903,021, Holden et al.

Heretofore, fabric manufacturers have subjected fabrics produced from synthetic materials to special treatment(s) subsequent to the weaving thereof in order to obtain a product having the desired physical characteristics. These treatments are time-consuming and involve the use of expensive equipment. For example, and referring to FIGS. 1, 2 and 3, in the case of such a forming fabric 2 which has been woven flat and subsequently joined, the warp yarns 4 have crimps therein, herein referred to as "vertical crimps," which undulate in a plane normal to the paper contacting surface of the fabric. These vertical crimps are the result, in part, of the warp yarns 4 bending over and under the weft or filling yarns 6 during the weaving of the fabric 2. When the fabric 2 is positioned on the papermaking machine, the warp yarns 4 extend in the direction of the path of travel of the fabric, which path direction is referred to herein as the "machine" direction. Accordingly, when the fabric 2 is in operation and subjected to machine direction tensions as high as 80 pounds per lineal inch of width, (referred to in FIG. 2 by arrows T--T) there is a tendency for the warp yarns 4 to straighten out; that is, the vertical crimp in the machine direction is reduced as a result of the high machine direction tensions. In addition, the straightening out of the machine direction yarns causes "crimp interchange;" that is, by reducing the vertical crimp in the machine direction yarns the vertical crimp in the cross-machine direction is increased. The net effect is that during the useful life of the fabric it elongates in the machine direction, and becomes narrower in the cross-machine direction, to such an extent that it must be removed from the paper machine. The fabric manufacturer faces a dilemma, however, in that although he could substantially reduce the vertical crimp in the machine direction yarns and thereby reduce the tendency of the fabric to elongate in the machine direction during the papermaking operation by (a) producing a fabric which is undersize; that is, the circumferential length of which is less than that which is required in order for the fabric to properly fit on the paper-making machine, and (b) prior to positioning the fabric on the paper machine, stretching the fabric in the machine direction until it reaches the required length, since the fabric has been woven flat, it is desirable to maintain the vertical crimp in the machine direction yarns in order to prevent the fabric from rupturing in the seam area. For example, Schuster, U.S. Pat. No. 3,238,594 discloses a forming medium which has been woven flat and subsequently joined, the join being dependent, in part, upon the vertical crimp in the machine direction yarns. The tendency of the fabric seam to rupture is reduced as a result of the interlocking in the seam area of the machine direction yarns with those yarns which extend in a direction substantially at right angles to the machine direction yarns, herein referred to as cross-machine direction yarns. Such interlocking is dependent, in part, upon the vertical crimp in the machine direction yarns. Fabric manufacturers have coped with the dilemma of producing a fabric which has been woven flat and subsequently joined, which has a high degree of elongation resistance and yet enough vertical crimp in the machine direction yarns to reduce the tendency for the seam or join to rupture, by subjecting the fabric to various stabilization treatments. An example of a resin treatment suitable for use on papermakers forming fabrics is that set forth in U.S. Pat. No. 3,032,441, Beaumont et al.

At least one fabric manufacturer has attempted to cope with this dilemma by endless weaving forming fabrics from synthetic materials. Since the fabric is woven endless there is no seam, and therefore any vertical crimp in the machine direction yarns can be substantially eliminated so that fabric elongation in the machine direction will be substantially reduced during operation on the paper machine. Forming fabrics which have been woven endless, however, must also be subjected to subsequent stabilization treatments. Since there is very little, if any, vertical crimp in the machine direction yarns and since these yarns are substantially parallel to each other, there will be a tendency for the cross-machine direction yarns, which yarns pass over and under the machine direction yarns in a sequence depending upon the weave pattern, to move or slide relative to each other and the machine direction yarns, thereby varying the dimensions of the rectangular interstices in the fabric. This "shoving" of the cross-machine direction yarns can be substantially reduced by subjecting the fabric to a stabilization treatment, as, for example, that treatment described and claimed in the Beaumont et al patent referred to above.

Accordingly, it is an object of this invention to produce a forming medium which will not elongate significantly in the machine direction when operating on a paper machine.

Another object of this invention is to produce a forming medium which does not narrow significantly in the cross-machine direction when operating on a paper machine.

Still another object of this invention is to produce a forming medium, the cross-machine direction yarns of which do not move significantly relative to each other or to the machine direction yarns.

A further object of this invention is to produce a forming fabrich which is dimensionally stable in both the machine and cross-machine directions without the necessity of subjecting the fabric to further stabilization treatment.

Still a further object of this invention is to produce a forming fabric, the permeability of which does not significantly vary during the life of the fabric.

SUMMARY OF THE INVENTION

This invention achieves these and other objects by means of a forming medium comprising a crowded weave having interwoven substantially nondeformable warp and weft yarns in which the axes of the machine direction yarns reside substantially in the same longitudinal plane and have crimps therein which undulate in the cross-machine direction.

DESCRIPTION OF DRAWINGS

This invention may be cearly understood by reference to the attached drawings in which:

FIG. 1 is a fragmentary plan view of a forming fabric embodying the prior art;

FIG. 2 is a sectional view along the line 2--2 in FIG. 1;

FIG. 3 is a sectional view along the line 3--3 in FIG. 1;

FIG. 4 is a fragmentary plan view of a forming fabric embodying the teachings of the present invention;

FIG. 5 is a sectional view along the line 5--5 in FIG. 4; and

FIG. 6 is a sectional view along the line 6--6 in FIG. 4.

DESCRIPTION OF PREFERRED EMBODIMENT

The embodiment of this invention, which is illustrated in FIGS. 4, 5 and 6, is one which is particularly suited for achieving the objects of this invention. FIG. 4 depicts a single layered fourdrinier fabric 12 which comprises yarns woven endless so that the warp yarns 14 extend in the crossmachine direction and the filling yarns 16 extend in the machine direction. A suitable material for these yarns is 8 mil monofilament synthetic polyester. It should be noted that forming fabric 12 may be a multilayered fabric, as, for example, that which is disclosed in Justus et al, U.S. Pat. No. 3,127,308, in which case the teachings of this invention are applicable to each layer thereof. It should be further noted that the scope of the present invention is not limited to the polyester monofilament yarns described above. As explained in detail hereinafter any yarn, wire, or strand-like material, herein referred to as "yarn," having the requisite physical characteristics for use as a constituent of a forming medium may be used, providing such material is substantially nondeformable, and, in the case where a fabric embodying the present invention is produced by shrinking the cross-machine direction yarns, as described, hereinafter, is susceptable to shrinking and maintaining its reduced length. By nondeformable is meant that the yarns in the completed fabric are of such a nature that when the fabric is in use their cross-sectional dimensions will remain substantially the same under pressure applied thereto as a result of tension applied to the fabric. As will be seen, this characteristic is utilized to ensure that the diameter d of the cross-machine direction yarns will not be less than the average distance h measured in the cross-machine direction between adjacent machine direction yarns. For example, other types of monofilament yarns, such as polyamides, may be used. Most untreated multifilament yarns will not be suitable for the purposes of the present invention since, unless specially treated, such yarns are usually deformable. In certain instances, however, multifilament yarns may be rendered substantially nondeformable, either prior or subsequent to weaving, as, for example, by impregnating them with resin. It should be noted that by the use of the word "diameter" it is not meant to limit the scope of the present invention to the use of yarns, a cross-sectional view of which is circular. Rather, "diameter" is used in its broader sense and means the length of a straight line through the center of gravity of a cross-sectional view of a circular or noncircular yarn.

FIG. 4 depicts a fabric 12 which incorporates a four-harness satin weave. In one suitable such construction there are 84 picks per inch (machine direction yarns) and 49 ends per inch (cross-machine direction yarns). While FIG. 4 depicts a four-harness satin weave, other types of weaves, for example, twill weaves, may be utilized. Referring to FIGS. 5 and 6, it can be seen that, for example, by endless weaving 8 mil polyester monofilament yarns in a four-harness satin weave having 49 ends per inch and 84 picks per inch, a fabric 12 is produced wherein the axes of the machine direction yarns 16 lie substantially in the same longitudinal plane; that is, the vertical distance v between the axes of adjacent machine direction yarns is less than the diameter d of the cross-machine direction yarns. In addition, a weave pattern is effectuated, which is referred to herein as a "crowded weave," wherein the interrelationship between the machine and cross-machine direction yarns is such that the diameter of some, and preferably all, of the cross-machine direction yarns 14 is greater than the average distance, measured in the cross-machine direction, separating the peripheral surfaces of adjacent machine direction yarns 16. This will be the case, for example, when 8 mil monofilaments are woven endless in a four-harness satin weave having 62 to 95 picks per inch.

As depicted in FIG. 4, machine direction yarns 16 have crimps therein, herein referred to as "lateral crimps," which undulate in the cross-machine direction in the longitudinal plane of the fabric; that is, in viewing either surface of the fabric, the machine direction yarns 16 undulate to the left and right. This undulation is such that the axes of adjacent machine direction yarns are furthest apart at those points where a cross-machine direction yarn interlaces therebetween, as, for example, where cross-machine direction yarn 14 interlaces from beneath the fabric 12 and up between adjacent machine direction yarns 16, 16'. Similarly, the axes of adjacent machine direction yarns are closest together at those points where there is no cross-machine direction yarn therebetween. Referring to FIG. 4, it can be seen that many of the interstices in the fabric have a trapezoidal configuration as a result of the lateral crimp in the machine direction yarns. As explained in detail hereinafter, these lateral crimps result from (1) the use of yarns which are substantially nondeformable; (2) the maintaining of the machine direction yarns 16 in substantially the same longitudinal plane; and (3 ) the crowded weave pattern referred to above.

It has been found that a forming fabric embodying the teachings of the present invention exhibit unexpected results when placed upon a papermaking machine. For example, although there are lateral crimps in the machine direction yarns, when the fabric is placed in operation on a papermaking machine and subjected to the high machine direction tensions referred to above, the lateral crimp is maintained, elongation of the machine direction yarns is negligible, and crimp interchange is substantially reduced. Without wishing or intending to be bound by a theory of operation, and referring to FIG. 4, it is believed that the lateral crimp is not removed from the machine direction yarns 16 during the papermaking operation because of at least two interrelated factors. Since all of the machine direction yarns 16 lie in substantially the same plane, when tension is applied to the fabric in the machine direction (depicted by arrows T'--T'), any tendency which the machine direction yarns 16 might have to straighten out would be exhibited by cross-machine direction movement, in that plane, of the machine direction yarns. Such lateral movement will cause machine direction yarns 16 to exert a force (denoted by arrows F--F) against an adjacent cross-machine direction yarn 14 in an attempt to straighten out. However, since all of the yarns are substantially nondeformable, the cross-machine direction yarns 14 will offer an opposing force which is equal in magnitude (depicted by arrows F'--F'), thereby preventing the removal of the lateral crimp in the machine direction yarns 16.

Another unexpected result is that since the lateral crimp is maintained in the machine direction yarns 16, the cross-machine direction yarns 14 do not move with reference to each other or the machine direction yarns. It is believed that this is the result of the interlocking of the laterally crimped machine direction yarns 16 with the vertically crimped cross-machine direction yarns 14. In addition, however, there will be a tendency for the cross-machine direction yarns 14 to resist machine direction movement along and in the interstices of the fabric 12 because of the trapezoidal configuration of the interstices; that is, there will be little tendency for the cross-machine direction yarns 14 to slide into the wedge-shaped end of the fabric opening 18.

The dimensional stability achieved by this invention has the added advantage of being obtained without the necessity for subjecting the fabric to a subsequent resin-impregnated heat stabilization or other treatment although, of course, such treatments might be employed if desired.

The process of the invention comprises weaving a fabric from nondeformable yarns in such a manner that the machine direction yarns lie substantially in the same plane, as will be the case, for example, when such a fabric is woven endless, and such that a crowded weave is perfected. The specific pattern chosen must be such that a cross-machine direction yarn does not interlace between two adjacent machine direction yarns at a point where such cross-machine direction yarn will interfere with the effectuation of a lateral crimp in the machine direction yarn. For example, and referring to FIG. 4, cross-machine direction yarn 14 should not interlace between machine direction yarns 16 at point A, because to do so would interface with the lateral movement of yarn 16, as indicated by arrow L, which would prevent yarn 16 from obtaining a lateral crimp at that point. As a practical matter, what this means is that any weave pattern may be used other than a plain weave.

The crowded weave may be perfected during the weaving of the fabric or subsequent thereto. If done during the weaving of the fabric, the pick count; that is, the number of machine direction yarns per inch in a fabric which is woven endless, will have to be such that, as noted above, the cross-machine direction spacing between adjacent machine direction yarns is less than the diameter of at least some of the warp or cross-machine direction yarns. The following table lists four fabric examples, each of which comprises 8 mil polyester monofilament yarns which have been woven endless in a four-harness satin weave, the yarn count being such that a crowded weave has been perfected:

TABLE No. 1 ______________________________________ Fabric Number 1 2 3 4 ______________________________________ Ends per inch (Cross-Machine Direction) 45 50 55 60 Picks per inch (Machine Direction) 79 74 66 64 Average Hole Dimension (mils) (Cross-Machine Direction) 4.7 5.1 7.3 7.8 ______________________________________

In the alternative, the crowded weave may be perfected subsequent to the weaving of the fabric. This may be accomplished by weaving the fabric such that the diameter of the cross-machine direction yarns is equal to or less than the average distance measured in the cross-machine direction between the peripheral surface of adjacent machine direction yarns, and subsequently reducing the length of the cross-machine direction yarns by shrinking same. For example, the length of the cross-machine direction yarns can be reduced by applying machine direction tension to the fabric while subjecting it to heat. In such a case, the amount of pressure and degree of heat will vary depending upon the results desired. In this manner, the cross-machine direction yarns will shrink in length, thereby pulling the machine direction yarns closer together. The heating of the fabric should be continued until a crowded weave is perfected. Table No. 2 refers to the same four fabric examples listed in Table No. 1 subsequent to subjecting each of them to heat stabilization. The fabrics listed in Table No. 2 were subjected to a maximum machine direction tension of about 95 pounds per lineal inch of width for about 2 hours, and to a maximum temperature of about 400.degree. F.

TABLE No. 2 ______________________________________ Fabric Number 1 2 3 4 ______________________________________ Ends per inch (Cross-Machine Direction) 45 49 54 59 Picks per inch (Machine Direction) 87 84 75 72 Average Hole Dimension (mils) (Cross-Machine Direction) 3.5 3.9 5.4 5.9 ______________________________________

EXAMPLE 1

A single layered forming fabric embodying the teachings of the present invention was woven endless using 8 mil monofilament synthetic polyester yarns. The fabric was woven into a four-harness satin weave having 70 picks per inch (machine direction yarns) and 50 ends per inch (cross-machine direction yarns), the distance between the peripheral surfaces of adjacent machine direction yarns measuring 6.4 mils. In order to perfect an even tighter weave, the fabric was subjected to about 50 pounds per lineal inch tension in the machine direction and heated to a temperature of about 400.degree. F. for about 4 minutes. The finished product had 80 picks per inch and 49 ends per inch, the average distance measured in the cross-machine direction between the peripheral surfaces of adjacent machine direction yarns thereby being reduced to 4.5 mils. The fabric was subsequently positioned on a fourdrinier machine in the manufacture of fine paper. It was observed that fabric stretch in the machine direction and shoving of the cross-machine direction yarns was substantially eliminated, and the quality of the paper produced was not reduced, notwithstanding that the fabric was in operation for a period of 320 days. Theretofore, the average life of synthetic forming fabrics on the same machine was about 73 days.

EXAMPLE 2

A forming fabric was manufactured as set forth in Example 1 except that subsequent to subjecting the fabric to heat there were 82 picks per inch, and the average distance measured in the cross-machine direction yarns between the peripheral surfaces of adjacent machine direction yarns was reduced accordingly from 6.4 mils to 4.2 mils. This fabric was also positioned on a fourdrinier machine in the manufacture of fine paper. As in the case of the fabric referred to in Example 1, fabric stretch in the machine direction and shoving of the cross-machine direction yarns was observed to be substantially reduced, and the quality of the paper produced was not reduced.

EXAMPLE 3

Another forming fabric was manufactured as set forth in Example 1, except that subsequent to the weaving of the fabric there were 65 picks per inch, the average distance measured in the machine direction between the peripheral surfaces of machine direction yarns being 7.5 mils. This fabric was also subjected to the same heat treatment as referred to in Example 1, subsequent to which there were 75 picks per inch, the average distance between adjacent machine direction yarns being reduced to 5.3 mils. This fabric has been running on a papermaking machine which produces fine paper for 65 days and is still running with results similar to these noted in Example 1 and 2.

The embodiments which have been described herein are but some of several which utilize this invention and are set forth here by way of illustration but not of limitation. It is apparent that many other embodiments which will be readily apparent to those skilled in the art may be made without departing materially from the spirit and scope of this invention.

Claims

I claim:

1. A forming belt for a papermaking machine comprising:

a. nondeformable warp and weft yarns interwoven to form said belt with certain of said yarns extending in the lengthwise direction of said belt and other yarns extending in the widthwise direction of said belt, said widthwise yarns being woven such that they are not interlaced between two adjacent lengthwise yarns at a point where said widthwise yarns will interfere with lateral crimping in said lengthwise yarns;

b. the vertical distance between the axes of adjacent lengthwise yarns being less than the diameter of said widthwise yarns to substantially reduce vertical crimp in said lengthwise yarns; and,

c. said widthwise yarns having a diameter, measured at a point where said widthwise yarns contact adjacent lengthwise yarns, which is greater than the arithmetical mean displacement between adjacent surfaces of said lengthwise yarns, the lateral distance between adjacent lengthwise yarns varying substantially continuously along the length of the fabric to accommodate the interlacing of said widthwise yarns.

2. A forming belt for a papermaking machine comprising:

a. nondeformable synthetic monofilament warp and weft yarns interwoven to form said belt with certain of said yarns extending in the lengthwise direction of said belt and other yarns extending in the widthwise direction of said belt, said widthwise yarns being woven such that they are not interlaced between two adjacent lengthwise yarns at a point where said widthwise yarns will interfere with lateral crimping in said lengthwise yarns;

b. the vertical distance between the axes of adjacent lengthwise yarns being less than the diameter of said widthwise yarns to substantially reduce vertical crimp in said lengthwise yarns; and,

c. said widthwise yarns having a diameter, measured at a point where said widthwise yarns contact adjacent lengthwise yarns, which is greater than the arithmetical mean displacement between adjacent surfaces of said lengthwise yarns, the lateral distance between adjacent lengthwise yarns varying substantially continuously along the length of the fabric to accommodate the interlacing of said widthwise yarns.

3. A forming belt for a papermaking machine comprising:

a. nondeformable synthetic monofilament warp and weft yarns which consist substantially entirely of one or more synthetic materials selected from the group consisting of polyamides, polyesters, acrylics and copolymers interwoven to form said belt with certain of said yarns extending in the lengthwise direction of said belt and other yarns extending in the widthwise direction of said belt, said widthwise yarns being woven such that they are not interlaced between two adjacent lengthwise yarns at a point where said widthwise yarns will interfere with lateral crimping in said lengthwise yarns,

b. the vertical distance between the axes of adjacent lengthwise yarns being less than the diameter of said widthwise yarns to substantially reduce vertical crimp in said lengthwise yarns; and,

c. said widthwise yarns having a diameter, measured at a point where said widthwise yarns contact adjacent lengthwise yarns, which is greater than the arithmetical mean displacement between adjacent surfaces of said lengthwise yarns, the lateral distance between adjacent lengthwise yarns varying substantially continuously along the length of the fabric to accommodate the interlacing of said widthwise yarns.

4. A forming belt for a papermaking machine comprising:

a. nondeformable warp and weft yarns which consist substantially entirely of one or more synthetic materials selected from the group consisting of polyamides, polyesters, acrylics and copolymers interwoven in a four-harness sateen weave to form said belt with certain of said yarns extending in the lengthwise direction of said belt and other yarns extending in the widthwise direction of said belt, said widthwise yarns being woven such that they are not interlaced between two adjacent lengthwise yarns at a point where said widthwise yarns will interfere with lateral crimping in said lengthwise yarns;

b. the vertical distance between the axes of adjacent lengthwise yarns being less than the diameter of said widthwise yarns to substantially reduce vertical crimp in said lengthwise yarns; and,

c. said widthwise yarns having a diameter, measured at a point where said widthwise yarns contact adjacent lengthwise yarns, which is greater than the arithmetical mean displacement between adjacent surfaces of said lengthwise yarns, the lateral distance between adjacent lengthwise yarns varying substantially continuously along the length of the fabric to accommodate the interlacing of said widthwise yarns.

5. An endless woven forming belt for a papermaking machine comprising:

a. nondeformable warp and weft yarns interwoven to form said belt with weft yarns extending in the lengthwise direction of said belt and warp yarns extending in the widthwise direction of said belt, said warp yarns being woven such that they are not interlaced between two adjacent weft yarns at a point where said warp yarns will interfere with lateral crimping in said weft yarns,

b. the vertical distance between the axes of adjacent weft yarns being less than the diameter of said warp yarns to substantially reduce vertical crimp in said weft yarns; and,

c. said warp yarns having a diameter, measured at a point where said warp yarns contact adjacent weft yarns, which is greater than the arithmetical mean displacement between adjacent surfaces of said weft yarns, the lateral distance between adjacent weft yarns varying substantially continuously along the length of the fabric to accommodate the interlacing of said warp yarns.

6. A forming belt for a papermaking machine comprising:

a. nondeformable warp and weft yarns interwoven to form said belt with warp yarns extending in the lengthwise direction of said belt and weft yarns extending in the widthwise direction of said belts, said weft yarns being woven such that they are not interlaced between two adjacent warp yarns at a point where said weft yarns will interfere with lateral crimping in said warp yarns;

b. the vertical distance between the axes of adjacent warp yarns being less than the diameter of said weft yarns to substantially reduce vertical crimp in said warp yarns; and,

c. said weft yarns having a diameter, measured at a point where said weft yarns contact adjacent warp yarns, which is greater than the arithmetical mean displacement between adjacent surfaces of said warp yarns, the lateral distance between adjacent warp yarns varying substantially continuously along the length of the fabric to accommodate the interlacing of said weft yarns.

7. An endless woven forming belt for a papermaking machine comprising:

a. nondeformable synthetic monofilament polyester warp and weft yarns interwoven in a four-harness sateen weave to form said belt with 62 to 95 weft yarns per inch extending in the lengthwise direction of said belt and warp yarns extending in the widthwise direction of said belt, said warp yarns being woven such that they are not interlaced between two adjacent weft yarns at a point where said warp yarns will interfere with lateral crimping in said weft yarns;

b. the vertical distance between the axes of adjacent weft yarns being less than the diameter of said warp yarns to substantially reduce vertical crimp in said weft yarns; and,

c. said warp yarns having a diameter, measured at a point where said warp yarns contact adjacent weft yarns, which is greater than the arithmetical mean displacement between adjacent surfaces of said weft yarns, the lateral distance between adjacent weft yarns varying substantially continuously along the length of the fabric to accommodate the interlacing of said warp yarns.

8. A method of producing a forming belt for a papermaking machine with certain of said yarns extending in the lengthwise direction of said belt and other yarns extending in the widthwise direction of said belt comprising the steps of weaving said belt from nondeformable warp and weft yarns with said widthwise yarns being woven such that they are not interlaced between two adjacent lengthwise yarns at a point where said widthwise yarns will interfere with lateral crimping in said lengthwise yarns, and with the vertical distance between the axes of adjacent lengthwise yarns being less than the diameter of said widthwise yarns to substantially reduce vertical crimp in said lengthwise yarns, and with the arithmetical mean displacement between adjacent surfaces of said lengthwise yarns being less than the diameter of said widthwise yarns, measured at a point where said widthwise yarns contact adjacent lengthwise yarns, the lateral distance between adjacent lengthwise yarns varying substantially continuously along the length of the fabric to accommodate the interlacing of said widthwise yarns.

9. A method of producing a forming belt for a papermaking machine having certain of said yarns extending in the lengthwise direction of said belt and having other of said yarns extending in the widthwise direction of said belt comprising the steps of weaving said belt from nondeformable warp and weft yarns with said widthwise yarns being woven such that they are not interlaced between two adjacent lengthwise yarns at a point where said widthwise yarns will interfere with lateral crimping in said lengthwise yarns, and with the vertical distance between the axes of adjacent lengthwise yarns being less than the diameter of said widthwise yarns to substantially reduce vertical crimp in said lengthwise yarns, and reducing the length of the widthwise yarns by shrinking said yarns until the arithmetical mean displacement between adjacent surfaces of said lengthwise yarns is less than the diameter of said widthwise yarns, measured at a point where said widthwise yarns contact adjacent lengthwise yarns, while holding said lengthwise yarns such that said vertical distance remains less than said diameter, to allow the lateral between adjacent lengthwise yarns to vary substantially continuously along the length of the fabric to accommodate the interlacing of said widthwise yarns.

10. A method of producing a forming belt for a papermaking machine having certain of said yarns extending in the lengthwise direction of said belt and having other of said yarns extending in the widthwise direction of said belt comprising the steps of weaving said belt from nondeformable warp and weft yarns with said widthwise yarns being woven such that they are not interlaced between two adjacent lengthwise yarns at a point where said widthwise yarns will interfere with lateral crimping in said lengthwise yarns, and with the vertical distance between the axes of adjacent lengthwise yarns being less than the diameter of said widthwise yarns to substantially reduce vertical crimp in said lengthwise yarns, and reducing the length of the widthwise yarns by subjecting said belt to lengthwise tension and heat until the arithmetical mean displacement between adjacent surfaces of said lengthwise yarns is less than the diameter of said widthwise yarns, measured at a point where said widthwise yarns contact adjacent lengthwise yarns, while holding said lengthwise yarns such that said vertical distance remains less than said diameter, to allow the lateral distance between adjacent lengthwise yarns to vary substantially continuously along the length of the fabric to accommodate the interlacing of said widthwise yarns.

11. A method of producing an endless woven forming belt for a papermaking machine with weft yarns extending in the lengthwise direction of said belt and warp yarns extending in the widthwise direction of said belt comprising the steps of weaving said belt from nondeformable yarns with said warp yarns being woven such that they are not interlaced between two adjacent weft yarns at a point where said warp yarns will interfere with lateral crimping in said weft yarns, and with the vertical distance between the axes of adjacent weft yarns being less than the diameter of said warp yarns to substantially reduce vertical crimp in said weft yarns, and with the arithmetical mean displacement between adjacent surfaces of said weft yarns being less than the diameter of said warp yarns, measured at a point where said warp yarns contact adjacent weft yarns, the lateral distance between adjacent weft yarns varying substantially continuously along the length of the fabric to accommodate the interlacing of said warp yarns.