FI96887B - Paper machine fabric with flat machine direction yarns - Google Patents

Description

96887

INDUSTRIAL FABRICS WITH FLAT-MACHINE-ORIENTED YARNS

This invention relates to industrial fabrics, and more particularly to fabrics comprising flat monofilament yarns.

BACKGROUND OF THE INVENTION Paper machines generally comprise three parts: forming, pressing and drying. Paper machine fabrics are used to transport a continuous sheet of paper through papermaking equipment during papermaking. The requirements and desired properties of paper machine fabrics will vary depending on the part of the machine where those fabrics are used.

With the development of synthetic yarns, shaped monofilament yarns have been used to form paper machine fabrics. For example, U.S. Patent 4,290,209 discloses a fabric woven from flat monofilament hooks; U.S. Patent No. 4,755,420 describes a nonwoven structure in which the fabric of a paper machine comprises spirals made of flat monofilament yarns.

Numerous tissues are known in the art that are used to achieve different results. For example, U.S. Patent 20,438,788 describes a drying fabric having three layers of cross-machine direction yarns woven together with flat machine direction monofilament yarns to form unbonded yarn runs on both the top and bottom surfaces of the fabric. The yarn runs tend to form a smooth surface on the fabric.

Permeability is an important criterion in the structure of paper machine fabrics. In particular, for fabrics made to run at high speeds in modern drying equipment, it is desirable to provide drying fabrics with relatively low permeability.

U.S. Patent 4,290,209 discloses the use of flat monofilament yarns woven side by side to provide a fabric with reduced permeability. Although the flat warp yarns are woven side by side with each other, additional means, such as filler yarns, are needed to reduce the permeability of the fabric. As noted in said patent, it is desirable to avoid the use of fluffy, bulky filler yarns to reduce permeability, as they make the fabric susceptible to adhesion or water retention.

U.S. Patent No. 2,968,887 and U.S. Patent 4,755,420 address practical limitations in the aspect ratio (cross-sectional width to height) of machine direction warp yarns defining the fabric structure of the fabric. The highest practical page-to-5 ratio found in these patents is 3: 1, and the aspect ratio is preferably less than 2: 1.

U.S. Patent 4,621,663, assigned to the assignee of the present invention, describes one attempt to use high aspect ratio yarns (on the order of 5: 1 10 and above) to define the surface of a paper machine dryer fabric.

As described in that patent, a woven base fabric is provided to support high aspect ratio surface yarns. The woven base fabric comprises conventional round yarns and provides structural support and stability to the fabric described in that patent.

U.S. Patent 4,815,499 describes the use of flat yarns in connection with a forming fabric. This patent describes a composite fabric consisting of an upper fabric and a lower fabric bonded together by binding yarns. The aspect ratios used for the flat machine direction yarns 20 in both the top and bottom fabrics are well below 3: 1. In use, the paper machine fabrics are formed into endless belts. Weaving techniques are available that initially weave fabrics endless. However, there are practical limitations to the overall size of endless woven fabrics as well as the associated installation difficulties. Besides, not all papermaking equipment is designed to receive endless fabric.

Flat woven fabrics are often supplied with opposite ends that are seamed together when the fabric is installed in papermaking equipment. Usually, one end of the fabric 4 is threaded through a meandering path defined by the papermaking equipment and then joined to the opposite end to form a continuous belt.

35 Various sealing techniques are well known in the art.

One known seaming method is to form machine direction yarns at each end of the fabric into a series of loops. The loops of the ends of the fabric are then joined together when the fabric 3 96887 is installed to define a channel through which the connecting pin is pushed to lock the ends together.

For example, U.S. Patent Nos. 4,026,331, 4,438,789, 4,469,142, 4,846,231, 4,824,525, and 4,883,096 disclose various pin seams using machine direction yarns to form end loops. However, in each of these patents, the machine direction yarn protrudes from the end of the fabric and weaves back into the fabric next to itself. Thus, the loops have an inherent factor of rotation or torsion and are not completely perpendicular to the plane of the fabric. U.S. Patent 4,883,096 specifically addresses this problem.

It would be desirable to provide a paper machine fabric in which the seaming seams of the machine direction have no torsion and / or rotation.

15 Summary and Objects of the Invention

The invention relates to an industrial fabric, for example a paper machine fabric, the opposite ends of which comprise the flat machine direction or KS monofilament yarns of the system woven together with the cross machine direction or KPS yarn system. The invention is characterized in that the KS yarns comprise pairs of vertically aligned upper and lower KS yarns, the selected lower KS yarns being cut back at a selected distance from the ends of the fabric 25; and a series of '· ·. · perpendicular end loops of selected KS yarns are formed at each end of the fabric, which are turned back into a loop and woven together with the KPS yarns directly below themselves in the space released by the respective cut lower KS yarns.

30

The fabric of the invention has a system of flat machine direction monofilament yarns that overlap to control the permeability of the fabric. The system of KS yarns comprises upper and lower yarns which overlap vertically in the vertical direction. Preferably, the upper KS yarns define unbound yarn runs on the upper surface of the fabric, and each upper KS yarn forms a pair in a vertical overlap with the lower KS yarn. The lower 4 96887 KS yarns may be woven as an inverted image of the upper KS yarns to provide unbonded yarn runs to the underside of the fabric, or they may be woven according to a different repeat pattern to provide a different surface to the underside of the fabric.

At least the upper KS yarns are flat monofilament yarns woven side by side to reduce the permeability of the fabric and to lock the machine direction of the overlapping pairs of KS yarns. In a preferred embodiment, yarns of the same type and size are used throughout the machine direction yarn system, and both the upper and lower KS yarns are woven side by side with the parallel upper and lower KS yarns. An overlapping, adjacent woven machine direction yarn system provides 15 stability and allows KS yarns a relatively high aspect ratio, cross section width to height, greater than 3: 1, with an aspect ratio preferably in the range of about 2: 1 to 6: 1. Machine direction yarns further define a series of perpendicular seaming loops to the opposite 20 ends of the fabric. The end portions of the lower KS yarns are removed and the ends of the upper KS yarns are turned back to the loops on themselves and woven again at the end of the fabric into the space released from the cut end portions of the lower KS yarns. The lower KS yarns can be woven as an inverted pattern of the upper KS yarns so that the curl of the upper KS yarns corresponds to the state of the fabric pattern of the lower KS yarns to which the ends of the upper KS yarns are woven back. This improves the strength of the seam.

The upper KS yarns forming the non-loops are also woven as appropriate when cutting back the corresponding lower KS yarns into the released space. Preferably, at least the upper KS yarns are woven side by side to lock the machine direction and the perpendicular orientation of the overlapping KS yarn pairs. In a preferred embodiment, yarns of the same type and the same geometric shape and size are used throughout the machine direction yarn system, and both upper and lower KS yarns are woven side by side with parallel upper and lower KS yarns.

Other objects and advantages will become apparent from the following description of the presently most preferred applications.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic representation of a paper machine fabric made in accordance with the technique of the present invention; Fig. 2 is a cross-sectional view of the fabric shown in Fig. 1 taken along line 2-2; Fig. 3a is a cross-sectional view of the fabric 10 shown in Fig. 1 taken along line 3-3; Figure 3b is a cross-section of a previously known tissue structure; Fig. 4a shows the orientation of the yarns of the fabric shown in Fig. 1 after the fabric is finished, showing only I 15 two overlapping KS yarns; Figures 4b, 4c and 4d show in series the formation of seaming loops of the fabric of the paper machine shown in Figure 1; Fig. 5a is a perspective view of a previously known seaming loop of a KS yarn; Fig. 5b is a perspective view of a perpendicular KS yarn sewing loop made in accordance with the present invention; Fig. 6 is a schematic representation of another embodiment of a fabric made in accordance with the present invention; Fig. 7 is a cross-sectional view of the fabric shown in Fig. 6 taken along line 7-7, Fig. 8 is a cross-sectional view of the fabric shown in Fig. 6 taken along line 8-8; Fig. 9 is a perspective view of a portion of the fabric shown in Figs. 6-8; Fig. 10 shows the orientation of the yarns in the finished fabric shown in Fig. 6, showing one KS yarn, »·! 1oppulenkkiä; Fig. 11 shows a top view of the opposite ends of the fabric formed according to Fig. 6 just before the ends of the pins are grounded together; Fig. 12 schematically shows a third alternative ... embodiment of a fabric made according to the technique of the present invention, showing only one pair of overlapping KS yarns; Fig. 13 96887 Fig. 13 schematically shows a fourth alternative embodiment of a fabric made according to the technique of the present invention showing only one pair of overlapping KS yarns; Fig. 14 schematically shows a fifth alternative embodiment of a fabric made according to the technique of the present invention, showing only one pair of overlapping KS yarns; Fig. 15 schematically shows a sixth alternative embodiment of a fabric made according to the technique of the present invention showing only one pair of overlapping KS yarns; Fig. 16 schematically shows a seventh alternative embodiment of a fabric made according to the technique of the present invention, showing only one pair of overlapping KS yarns; and Fig. 17 schematically shows an eighth alternative embodiment of a fabric made according to the technique of the present invention, showing only one pair of overlapping KS yarns.

A detailed description of the most preferred applications at present

Referring to Figures 1, 2 and 3a, there is shown a drying fabric 10 of a paper machine 20 comprising upper, middle and lower layer cross-machine direction yarns 11, 12, 13 (hereinafter KPS) interwoven with a system of KS yarns 14-19 which weave sequentially according to the selected repeat pattern. The KS system comprises upper KS yarns 14, 16, 18, 25 interweaving with KPS yarns 11, 12, and lower KS yarns 15, 17, 19 interweaving with KPS yarns 12, 13.

The upper KS yarns 14, 16, 18 define unbonded yarn runs on the upper surface of the fabric 10 by weaving over two 3 0 top layer KPS yarns 11 and dropping into the fabric to weave as an internal joint under one middle layer KPS yarn 12 and one KPS yarn 11 and then rising to the surface of the fabric to continue the yarn pattern. The unbound runs of the upper KS yarns 14, 16, 18 over the KPS yarns 11 of the upper layer 35 are staggered so that all the KPS yarns 11, 12 of the upper and middle layers are held in the fabric.

As will be appreciated by those skilled in the art, the weaving pattern shown in Figures 1, 2 and 3a results in a mash bond to the top surface of the fabric. Although the two-threaded twine weave shown in Figures 1, 2 and 3a is a preferred application, it will be apparent to those skilled in the art that the length of the thread, the number of KS yarns in the repetition pattern and the order of KS yarns can be selected as desired to create other patterns. dossiers or non-dossiers.

| As best seen in Figures 2 and 3a, the lower KS yarns 15, 17, 19 are woven directly below the respective upper KS yarns 14, 16, 18 in a vertically overlapping relationship. The lower yarns are woven into an inverted image of their respective upper yarns. Each lower KS yarn 15, 17, 19 runs under the two KPS yarns 13 of the lower layer, rises into the fabric over one KPS yarn 13 and forms an articulated middle layer around one KPS yarn 12, after which the yarn 15 returns to the lower surface of the fabric to continue under the next KPS yarn 13.

With respect to each pair of overlapping yarns, the internal joint formed by one KS yarn around the middle layer of KPS yarns 12 remains hidden by the running of the other KS yarn. For example, in Figures 1 and 3a, the lower KS yarn 15 is illustrated to weave a joint over the KPS yarn 12, while the KS yarn 14 weaves its run over the KPS yarns 11, thus hiding the inner joint of the lower KS yarn 15. Similarly, in Figures 1 and 3a, the upper KS yarn 18 is illustrated to weave a joint under the KPS yarn 25 12, with the lower KS yarn 19 hiding it as it runs over the KPS yarns 13. The upper KS yarns 14, 16, 18 are woven side by side with respect to each other. This maintains their parallel machine direction orientation and reduces permeability. Such dense weaving of machine direction yarns 30 is known in the art as a 100% warp filling, as described in U.S. Patent 4,290,209. As described therein (and used herein), the actual warp number in the woven fabric can range from about 80 to 125% in one layer and yet it is considered a 100% warp -35 filling.

The constriction of the KS yarns 14, 16 and 18 also forces the KS yarns 15, 17, 19 into their overlapping position below the respective KS yarns 14, 16, 18. Most preferably, the KS yarns 15, 17, 96887 and 19 are the same size as the KS yarns 14, 16 and 18 so that they are also woven into a 100% warp filling. This results in the total fabric of the preferred application having a 200% warp filling of KS yarns.

5 Since the lower KS yarns 15, 17, 19 are preferably also woven into a 100% warp filling, they also have the effect of keeping the upper KS yarns 14, 16, 18 in an overlapping relationship with the lower KS yarns 15, 17, 19. .

Thus, the respective pairs of KS yarns 14 and 15, 16 and 17, 18 and 10 19 are double locked in place, thus increasing the stability of the fabric.

As disclosed in U.S. Patent No. 4,290,209, it has been found that machine direction flat yarns weave in more intimate contact around cross machine direction yarns 15 than round yarns. However, an aspect ratio of 3: 1 was considered a practical limit for such woven yarns in order to maintain the overall stability of the fabric. The present overlapping KS yarn system maintains fabric stability and machine direction strength and allows the use of yarns with an increased aspect ratio, preferably in the range of 2: 1 to 6: 1, to control permeability more effectively.

The high aspect ratio of KS yarns means reduced permeability. High aspect ratio yarns are wider and thinner than conventional flat yarns with an aspect ratio of less than 3: 1 and the same cross-sectional area. An equal cross-sectional area means that comparable yarns have essentially the same linear strength. The greater width of the high aspect ratio yarns 30 means fewer gaps in the width of the fabric than conventional yarns, so that there are fewer openings in the fabric through which liquids can flow. The relative thinness of the yarns with a high aspect ratio allows the flat KS yarns to be wound, i.e. to bind the cross-direction yarns of the machine 35 more efficiently, reducing the size of the gaps between the machine direction and machine cross-direction yarns.

For example, Figure 3b shows a woven fabric with a single layer, flat machine direction warp system having a warp yarn cross-sectional width of 1.5 units and a cross-sectional height of 1 unit, i.e. an aspect ratio of 1.5: 1. Such a fabric could be replaced by a fabric in which is the present double system of overlapping 5 KS yarns, the width of the KS yarns being twice as large, i.e. 3 units, and the height half, i.e. 0.5 units. Such KS yarns thus have a four times higher aspect ratio of 6: 1, as shown in Figure 3a.

10 Thinner, wider KS yarns control permeability more effectively, while the machine direction strength of the fabric remains essentially unchanged because the cross-sectional area of the KS yarns remains the same across the width of the fabric. For the example shown above, illustrated in Figures 15a and 3b, a conventional single system fabric of KS yarns has six conventional adjacent flat yarns with a fabric width of 9 units with a cross-sectional area of 9 square units, i.e. 6 x (1 y. X 1.5 y.). Thinner, wider yarns with a high aspect ratio 20 woven side by side as overlapping KS yarns define a fabric having three overlapping pairs of KS yarns 9 per unit width of fabric. Thus, the cross-sectional area of such a fabric is also 9 square units, i.e. (3 x (0.5 y. X 3 y.)) + (3 x (0.5 y. X 3 y.)) 25 units of fabric width.

In one example, the fabric was woven as shown in Figures 1, 2 and 3, wherein the KPS yarns 11, 12, 13 were polyester monofilament yarns having a diameter of 0.6 mm and woven together with KS yarns 14 to 19 which were 30 flat polyester monofilament yarns 1.12 mm wide and 0.2 mm high. Thus, flat KS yarns • ·; the aspect ratio was 5.6: 1. The fabric was woven using 48 warp yarns / inch and weaving machine tension. 40 PLI (pounds / linear inch) and 12.5 KPS percussion thread / inch / layer 35 (three layers).

The fabric was heat bonded in conventional heat bonding equipment under known conditions of temperature, stress and time for polyester monofilament yarns. For example, conventional polyester fabrics are heat-bonded with parameters ranging from 340 to 380 ° F, a tension of 6 to 15 PLI (pounds per linear inch), and a time of 3 to 4 minutes. However, due to their stable structure, the fabrics of the present invention are more permissive for variations in thermal bonding parameters.

The fabric had a warp coefficient of 6000 PLI (pounds per square inch) as measured by the American Society for Testing and Materials ASTM D-1682-64 standard. The fabric stretched less than 0.2% of the length during thermal bonding. This result makes the fabrication of the fabrics according to the present invention very reliable in achieving the desired dimensional properties compared to conventional fabrics.

The resulting heat-bonded fabric had 12.5 15 KPS yarns / inch / layer with a warp fill of 106% for both upper and lower KS yarns, resulting in an actual warp fill of 212% for the fabric. The permeability of the finished fabric is 83 CFM as measured by ASTM D-737-75.

As shown in Fig. 4a, when the fabric 10 is woven, the three layers of KPS yarns 11, 12, 13 are compressed.

This compression, together with the relatively thin dimension of the KS yarns, lowers the caliber of the fabric. Thus, the overall caliber of the fabric can be considered relatively low and not significantly higher than that of conventional fabrics woven without overlapping KS yarn pairs. In the example above, the finished fabric had a caliber of 0.050 inches.

Those skilled in the art will appreciate that if either the upper KS-30 yarns 14, 16, 18 or the lower KS yarns 15, 17, 19 are woven as a 100% warp filling, the total warp filling on the overlapping fabric will be significantly greater than 100%, which will help reduce the permeability of the fabric.

This fabric with overlapping KS yarns is found to have a significantly higher warp filling percentage than fabrics with an actual warp filling of 125% non-overlapping KS yarns, which is achieved by compression and lateral corrugation of the warp threads. Although 11 96887 200% warp filling is most suitable, the fabric can be woven with 100% filling for either the upper or lower KS yarns at a lower fill rate for other KS yarns using yarns that are not as wide as the KS-5 yarns that is woven with 100% warp filling. For example, the upper yarns 14, 16, 18 could be 1 unit wide, with the lower yarns 15, 17, 19 being 0.75 units wide, resulting in a fabric with a warp filling of 175% when killed.

Such variations can be used to provide a varied degree of permeability. Alternatively, such variations could be used in the manufacture of the forming fabric. In such a case, the lower KS yarns would be woven with 100% warp filling to define the machine side of the fabric and the upper KS yarns would be woven with a substantially lower filling percentage to provide a more transparent papermaking fabric.

The KS fabric of the overlapping pairs allows the formation of perpendicular seaming loops in the KS yarns. Referring to Figures 4a-d, after the fabric has been woven and thermally bonded 20 (Figure 4a), the KPS yarns are removed leaving the curled KS yarns 14, 15 exposed (Figure 4b). One of the overlapping pairs of yarns, e.g., the lower KS yarn 15, is cut backward by a selected distance, leaving the second exposed KS yarn 14 of the KS yarn pair and the free space between the KPS yarns 25, as shown in Figure 4c. The upper KS yarn 14 is then woven backwards into the fabric pattern in the space released by the lower KS yarn 15 so that a loop L is formed at the end of the fabric, as shown in Figure 4d. Preferably, 0.5 to 5.0 inches of the upper yarn 14 is woven backward into the fabric 30 to provide sufficient strength to the end loop and to ensure that the free end of the KS yarn 14 remains in the fabric of the fabric. The inverted fabric allows the curl of the upper KS yarn 14 to correspond to the space freed by the lower KS yarn 15, which further increases the strength of the end loop.

As shown by the dashed lines in Figure 4d, the adjacent pair of yarns 16, 17 are treated in the same manner. However, when .. the upper yarn 16 is turned back into a loop and woven back into the fabric, it is pulled against the KPS yarns. In the most suitable application, where the upper KS yarns are woven with 100% filling, the narrowing of the yarns ensures the perpendicular orientation of the seaming loops.

To provide a uniform seam on the fabric woven with the bonding pattern 5 illustrated in Figure 1, each upper KS yarn 14 forms a loop and the other upper KS yarns 16, 18 are woven backwardly against the outermost KPS yarn at the end of the fabric. Thus, every third upper KS yarn defines a loop such that a row of loops is formed at each end of the fabric. The seam is assembled by matching the opposite rows of loops together and inserting the pin wire between the mutually coordinated loops.

Preferably, the yarns 14 forming the loop would all be woven backwards into the fabric at approximately the same distance to provide sufficient strength to prevent the loops from being pulled off during normal use. The yarns 16, 18 forming the non-loops would preferably be woven backwards for a somewhat shorter distance, since no load is applied to those yarns during use. For example, the upper KS yarns 14 would be woven backwards by approximately 3 inches, the KS yarns 16 would be woven backward approximately 2 inches, and the KS yarns 18 would be woven backward approximately 1 inch. The respective lower layer yarns 15, 17, 19 would be cut to complete the backward weaving of the respective KS yarn pairs 14, 16, 18.

Figures 5a, 5b show a conventional seaming loop 50 compared to a perpendicular seaming loop L according to the present invention. In conventional looping techniques, the KS yarn 51 is woven backwards into the fabric itself, thereby inherently twisting and / or twisting the KS yarn 50. the wire is formed on the loop directly below itself and has no lateral displacement that would cause such rotation or torsion in the sealing loop.

Referring to Figures 6, 7 and 8, another preferred embodiment 35 of a fabric 20 made in accordance with the present invention is shown. The paper machine fabric 20 consists of a single layer of KPS yarns 21a, 21b interwoven with a system of overlapping KS yarns 22-25 weaving in the selected weave pattern. The KS yarn system comprises upper KS yarns 22, 24 defining yarn runs on the upper surface of the fabric 20 by weaving over three KPS yarns, below one KPS yarn 21a forming a hinge 5 and then returning to run over the next three KPS yarns continuing the pattern .

The lower KS yarns 23, 25 are woven directly below the respective upper KS yarns 22, 24 in a vertical overlapping relationship. The lower KS yarns are woven as an inverted image of their respective upper KS yarns. Each lower KS yarn 23, 25 runs under three KPS yarns, weaves upward around the next one KPS yarn 21a to form a hinge, and then continues running under the next three KPS yarns in the repetition pattern.

As can be seen from Figures 6 and 8, the joints formed by the lower KS yarns 23, 25 remain covered by the yarn runs formed by the upper KS yarns 22, 24. Likewise, the joints formed by the upper KS yarns 22, 24 remain covered by the yarn runs formed by the lower KS yarns 23, 25.

The caliber of the fabric in the vicinity of the articulated area shown in Figure 8 tends to be somewhat larger than the caliber of the fabric shown in Figure 7 at the non-articulated KPS yarns 21b. However, the KPS yarns 21a around which the joints are formed are curly, which reduces the caliber of the fabric in the area shown in Fig. 8. In addition, slightly larger diameter ornamental KPS yarns are more suitably used as the KPS yarns 21b shown in Figure 7 and around which no joints are woven with KS yarns, to eliminate the difference in fabric caliber. Preferably, the diameter of the thicker KPS yarn 21b is equal to the diameter of the thinner KPS yarn 21a plus the thickness t of the KS yarns.

In one example, the fabric was woven as shown in Figures 6-9, wherein the KPS yarns 21a, 21b were 35 0.6 and 0.8 mm diameter polyester monofilament yarns interwoven with KS yarns 22-25, which were flat polyester monofilament yarns having a width of 1.12 mm and height 0.2 mm. Thus, the flat KS yarns 96887; 14

S

The j aspect ratio was 5.6: 1. The fabric was woven using a total of 48 warp yarns per inch at a weaving machine tension of 40 PLI (pounds per linear inch) and 20 KPS percussion yarns per inch. The permeability averaged 90 CFM in the resulting fabric.

In another example, the fabric was woven according to Figs. 6, 7 and 8, wherein the KPS yarns 21a, 21b were polyester monofilament yarns 0.7 mm in diameter and woven together with KS yarns 22 to 25, which were flat polyester monofilament yarns having a width of 1, 12 mm 10 and height 0.2 mm. Thus, the aspect ratio of the flat KS yarns was 5.6: 1. The fabric was woven using 22 KPS percussion yarns per inch. The fabric was heat bonded using conventional methods. The fabric had a multiplier of 6000 PSI. The fabric stretched to less than 0.2% length during thermal bonding.

15 The resulting fabric had 22 KPS yarns per inch with 106% warp filling for both upper and lower KS yarns, followed by 212% actual warp filling for the fabric. The finished fabric had a caliber of 0.048 inches and an air permeability of 60 CFM.

As best seen in Figure 9, the high aspect ratio yarns 22-24 effectively bind the KPS yarns 21a in the fabric structure. The amount of this bond can be expressed as the degree of contact arc Θ and the area of contact bond, KSP as follows: 25 KSP = nd (Θ) w 360 ° where d = diameter of the KPS wire 30 Θ = degree of the arc between the KS and KPS wires contact w = width of KS yarn n = constant silicon 35 The degree of arc at which KS yarns 22 to 25 are in contact with KPS yarns 21a depends on the density of the KPS yarns in the fabric. In the example above, using alternately 0.6 mm and 0.8 mm KPS yarns with 0.2 mm thick KS-15 96887 yarns, the degree of contact arc can be maintained in the preferred range of 60 to 180 ° by varying the stroke rate of the KPS yarns from 14 strokes per inch up to 28.22 beats per inch.

In the preferred embodiment, where the stroke rate is 20 strokes per inch, the degree of contact arc Θ is approximately 101 °. This results in a bonding contact area of approximately 0.79 mm2 at each fabric joint.

The use of the applicant's high aspect ratio yarns, i.e. yarns with a width: thickness ratio of at least 3: 1, provides increased bonding contact of the flat KS yarns with the KPS yarns 21a. This gives a comparative example by converting the equation of the contact binding area, KSP, to be determined by the thickness of the KS yarns.

Since the width w of the KS yarn is equal to the thickness t of the KS yarn multiplied by the aspect ratio, w> 3t for yarns having an aspect ratio greater than 3: 1. Thus, fabrics made in accordance with the present invention using high aspect ratio KS yarns have an increased bonding of KPS yarns with 20 KS yarns such that: KSP> nd (Q) 3t 360 ° 25 As best seen in Figure 10, the seaming loops are formed by upper KS yarns 22. Corresponding lower KS yarns 23 the selected distance from the end of the fabric is cut and the upper KS yarns 22 are woven into the space released by the lower cut lower KS yarns 23.

The upper KS yarns 24 are likewise woven backwards into the space released by cutting backwards the lower KS yarns 25.

• ·

However, as best seen in Figure 10, the upper KS yarns 24 are woven backward against the outermost KPS yarn 21b.

As seen in Figure 11, a series of seaming loops are formed at each opposite end 27, 28 of the fabric. When the fabric is installed in the papermaking equipment, the respective end loops formed by the KS yarns 22 are fitted together and 16 96887 pins 29 are inserted through them to lock the matched loop sets.

Since the seaming loops L are formed by weaving back the KS yarns 22 directly below themselves, no lateral rotation or torsion is applied to the loop and the loops are perpendicular to the plane of the fabric. This facilitates the matching of the sets of loops at the opposite ends 27, 28 of the fabric. Perpendicular loops are particularly preferred when the KS yarns 22, 24 form 100% warp fill and the adjacent loops are separated by individual KS yarns having the same width as the KS loop yarns 22, as seen in Figure 10. Lateral rotation or torsion in the seaming loops makes the sealing step more difficult, especially when the loop receiving gaps between the loops 15 at one end of the fabric are substantially the same width as the loops at the opposite end of the fabric and vice versa.

Referring to the fabric shown in Figures 6-11, the loop-forming KS yarns 22 are preferably woven backward about 2 inches, while the non-loop-forming KS yarns 24 are preferably woven backward 1 inch.

Referring to Figure 12, a third embodiment of a paper machine fabric 30 is shown. The fabric 30 is comprised of a single layer of KPS yarns 31 interwoven with overlapping pairs of flat monofilament yarns into a selected repeat pattern. For clarity, only one pair of overlapping KS yarns is shown, which is the upper KS yarn 32 and the lower KS yarn 33. The upper KS yarns weave as a yarn run over the two KPS yarns 31, forming one joint under the next KPS yarn, and then repeated. Likewise, the lower KS yarns 30 are woven into an inverted view of the upper KS yarns, weaving under the two KPS yarns 31, forming a joint over the next KPS yarn 31 and then returning to the lower surface of the fabric in repetition. Since the repetition of both the upper and lower KS yarns is with respect to the three KPS yarns 31, a total of 35 different pairs of overlapping yarns form the binding pattern of the KS yarn system.

The fabric was woven according to Fig. 12, where the KPS yarns 31 were polyester monofilament yarns with a diameter of 17,968,877 and 0.7 mm, which were woven together with KS yarns which were flat polyester monofilament yarns having a width of 1.12 mm and a height of 0.2 mm. . Thus, the aspect ratio of the flat KS yarns was 5.6: 1. The fabric was woven 5 using 48 warp yarns per inch with a weaving machine tension of 60 PLI and 18 KPS strapping yarns per inch. The fabric was heat sealed using conventional methods. The fabric had a multiplier of 6000 PSI. The fabric stretched less than 0.2% in length during heat setting. The resulting fabric had 18 KPS yarns per 10 inch with 106% warp filling for both upper and lower KS yarns, followed by 212% actual warp filling for the fabric. The finished fabric had a caliber of 0.046 inches and an air permeability of 66 CFM.

Referring to Figure 13, a fourth embodiment of a paper machine fabric 40 is shown. The fabric 40 includes upper, middle, and lower layers of KPS yarns 41, 42, 43 woven together with overlapping pairs of flat monofilament yarns in a selected repeat pattern. For clarity, only one pair of overlaps is shown. KS yarns which are the upper KS yarn 44 and the lower KS yarn 45. The upper KS yarns weave into a yarn run over the two KPS yarns 41 of the upper layer, under the next yarn 41 and the middle layer yarn 42 to form one hinge, the next KPS yarn 41 below and then rise to the top with continued playback. Likewise, the lower KS yarns 25 weave as an inverted view of the upper KS yarns * ·, ·, weaving under the two KPS yarns 43 of the lower layer over the next KPS yarn 43 and the KPS yarn 42 of the middle layer forming a hinge, returning over the next KPS yarn 43 after the fabric to the bottom surface for repetition. Since the repetition of both the upper 30 and lower KS yarns is with respect to the four upper and lower KPS yarns 41, 43, a total of four different overlapping yarn pairs form the fabric pattern of the KS yarn system.

The fabric was woven according to Fig. 13, with the upper and 35 lower layer KPS yarns 41, 43 being nylon-coated multifilament polyester yarns having a diameter of 0.62 mm and the middle layer KPS yarns 42 being polyester monofilament yarns having a diameter of 18,968,887. mm, woven together with KS yarns 22 to 25, which were flat polyester monofilament yarns having a width of 0.60 mm and a height of 0.38 mm. Thus, the aspect ratio of the flat KS yarns was 1.58: 1. The fabric was woven using 96 warp yarns per inch weaving machine at a tension of 40 PLI and 15 KPS percussion yarns per inch per layer. The fabric was heat-fixed using conventional methods. The resulting fabric had 15 KPS yarns per inch per layer with 113% warp filling for both upper and lower KS yarns, with an actual warp filling of 226% for the fabric. The finished fabric had a caliber of 0.075 inches and an air permeability of 60 GFM.

Figures 14, 15 and 16 show a fifth, sixth and seventh embodiment of the present invention. Figure 14 shows the weaving of the long yarn run of the ver-15 ratchet on both sides of the fabric; Fig. 15 shows how the weaving of an overlapping KS yarn pair can define yarn lengths of different lengths on opposite sides of the fabric; and Figure 16 shows how the weaving of an overlapping pair of KS yarns can be used to form fabrics with KS joints on one side of the fabric.

The relatively long yarn runs that dominate the surfaces of the drying fabric are preferred for both the paper-bearing side and the machine side of the fabric. On the paper-carrying side, long wire runs provide a greater contact area with the paper sheet for increased heat transfer. On the machine side, long wire runs provide increased tread and contact area, reducing stress and vibration. The overlapping pair of KS yarns is multi-sided, allowing different surfaces to be defined above and below the fabric. Thus, the fabrics made in accordance with this invention can be used for other industrial purposes such as slurry drying.

Figure 14 shows a fabric 50 comprising three 35 layers of yarn 51, 52 and 53. In this construction, pairs of KS yarns, such as a pair of upper layer yarn 54 and lower layer yarn 55, define relatively long yarn runs on both the top and bottom surfaces of the fabric. The upper yarn 19 96887 54 weaves over the KPS yarn 51 of the five upper layers, falls into the fabric to form under one KPS yarn 52 of the middle layer of the joint, weaves under the next yarn 51 of the upper layer, and then repeats. The lower KS yarn 55 weaves in the reverse view below the five KPS yarns 53 of the lower layer, rising to the fabric over the next KPS yarn 53. over the KPS yarn 52 of the middle layer of the joint, then falling to the underside of the fabric, continuing to repeat. In such a structure, six pairs of overlapping KS-10 yarns are used to reproduce the fabric and are woven in succession in a selected order to provide the desired pattern on the fabric surfaces dominated by the runs of the KS yarns.

The embodiment shown in Fig. 15 shows a fabric 60 in which KS yarns are woven as a repetition of five yarns on the upper surface of the fabric and as a repetition of two yarns on the lower surface of the fabric. For example, the upper KS yarn 64 interweaves with the upper and middle KPS yarns 61, 62 in the same manner as the upper KS yarn 54 interweaves with the corresponding KPS yarns 51, 52 relative to the fabric 50 in Fig. 14. The lower KS yarn 65 forming with the overlapping pair of upper KS yarns 64, however, weaves in a repetitive run over the two yarns with respect to the lower and middle KPS yarns 63, 62. For example, the lower KS yarn 65 runs under the two KPS yarns 63 of the lower layer, rise 25 over the next KPS yarn 63, forming a hinge in the middle of one of the KPS yarns 62, and then falls to the lower surface of the fabric 60 to continue playback. . As with the other applications discussed above, the upper KS yarns of the corresponding overlapping pair cover the joints formed by the lower KS yarns and vice versa.

The structure shown in Figure 15 allows different surfaces to be defined on the top and bottom surfaces of the fabric while utilizing pairs of overlapping KS yarns.

The embodiment shown in Figure 16 shows another example 35 of a fabric 70 with five yarns running over five yarns that control the top surface of the fabric but KS joints on the bottom surface of the fabric. This type of structure can be advantageously used to form a forming fabric, where the upper surface of the fabric having relatively long yarn runs would be used as the machine side of the fabric and the articulated lower surface of the fabric would be used as the papermaking side.

The fabric 70 includes three layers of KPS yarns 71, 72, 573 that interweave with overlapping pairs of KS yarns to define this structure. For clarity, only one pair of overlapping pairs of KS yarns 74, 75 is shown. The upper KS yarn 74 is woven as a running pattern over five yarns with respect to the upper and middle layer KPS yarns 71, 10 72 in the same manner as the upper KS yarn 54 with respect to the fabric 50 shown in Fig. 14. The lower KS yarn 75 weaves three inner joints and three lower surface joints with respect to the middle and lower layer KPS yarns 72, 73 below each of the upper surface yarn-15 runs of its respective KS yarn pair 74. The repetition of the upper KS yarns is determined with respect to the six KPS yarns 71 of the upper layer, and the repetition of the lower KS yarns is determined with respect to only two KPS yarns 73 of the lower layer. Thus, six different pairs of overlapping KS yarns form a KS yarn system, which, as noted above, can be arranged so that the desired pattern is formed on the top surface of the fabric.

In general, for the tissues of overlapping pairs, the repetition of the upper KS yarns is evenly divisible by the repetition of the lower KS yarns, or an even multiple of this when determining the overlapping pairs. For example, in Fig. 12, the repetition of the upper KS yarns is six upper layer KPS yarns, which is evenly divisible by the repetition of the lower KS yarns, which are three lower layer KPS yarns.

In the eighth alternative embodiment 30 shown in Figure 17, the fabric 80 has a single layer of KPS yarns 81 and a representative overlapping pair of KS yarns 82, 83. The upper KS yarn 82 weaves with two yarn runs over the KPS yarns 81 during the repetition with respect to the three KPS yarns 81. The lower KS yarn 83 is woven in five yarn runs by repeating six KPS yarns 81 of the KPS yarns 81 35. Thus, in fabric 80, the repetition of the upper KS yarns, which is three, is a flat, multiple of the repetition of the lower KS yarns, six.

Various other tissue designs using the tissue structure of the overlapping pairs of the present invention may be formed within the scope of the present invention. For example, in some applications, it may be desirable to use surface runs of KS yarns over six or more KPS yarns. Such fabrics are easily formed in accordance with the present invention.

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Claims (10)

1. Industrial fabric, e.g. the fabric of a paper machine whose opposing ends comprise a system of machine-oriented plate or MD monofilament trees woven together with a system of transverse machine-direction or CMD trees, characterized in that the MD trees comprise vertical resistance upper and lower MD. tree pairs (22,23), wherein selected lower MD trees (23) have been cut backwards at a selected distance from the end of the fabric; and at each end of the fabric, a series of perpendicular end links of selected MD trees (22) are formed which are curved posterior to links and woven together with the CMD trees directly below themselves in the space that correspondingly cut lower MD trees release. 2. Fabric according to claim 1, characterized in that the CMD tree system consists of a layer of CMD trees. Fabric according to claim 1 or 2, characterized in that the rectangle ratio of the at least the upper MD trees is at least 3: 1. Fabric according to claim 3, characterized in that all the upper MD trees (22) forming a perpendicular end link are woven together with the CMD trees (21) directly below themselves; all lower MD trees (23, 25) have been cut backwards on: a selected distance from the end of the fabric; and the rest of the upper MD trees (24) have been woven together with the CMD trees (25) directly below themselves, retaining the outermost CMD trees (21b) in the fabric. 5. Fabric according to claim 4, characterized in that the upper MD trees (22) forming a perpendicular end link have all been woven in the rear essentially the same distance from the end of the fabric, which is greater than the back weaving of the rest of the upper MD. the trees (24); and 96887 the lower MD trees (23) forming pairs with the Upper MD trees forming links have been cut at a greater distance from the end of the fabric than the rest of the lower MD trees (25). Fabric according to claim 4, characterized in that the actual gutter filling for at least the upper MD trees is in the range of 80 - 125%. 7. Fabric according to claim 4, characterized in that the lower MD trees (23, 25) are connected to The CMD trees (21) as a mirror image of the corresponding upper MD trees (22, 24) at the MD tree pairs. Fabric according to claim 4, characterized in that every other upper MD tree at the ends of the fabric is a tree which forms a perpendicular link. Fabric according to claim 4, characterized in that every third upper MD tree at the ends of the fabric is a tree that forms a perpendicular link. Fabric according to any one of claims 1-3, characterized in that at each opposite end there is a first series of MD trees formed in a back link and connected to the CMD trees directly below themselves defining a series of perpendicular end links; and ·· 'at each opposite end there is another series of MD trees among the first series of trees that have been formed in a back link and woven together with the CMD trees directly below themselves and pour the outermost CMD trees into the fabric. t «