US3652389A - Adjustable fabric for use as a papermaking felt with zig-zag patterned cross machine yarns - Google Patents

Abstract

An endless fabric, such as a papermaker''s felt, composed of a series of generally parallel warp yarns and having cross machine yarns or fibers extending in a zig-zag pattern across the warp yarns. The cross machine yarns in each section of the zig-zag pattern extend at an acute angle up to 80* with respect to a line normal to the warp yarns. The cross machine yarns are stabilized in their zig-zag pattern by physical or chemical means, such as by needling or heat setting, but remain adjustable thereafter in angularity with respect to the warp yarns once installed on a papermaking machine.

Description

nited States Patent elland [451 Mar. 28, 1972 [54] ADJUSTABLE FABRIC FOR USE AS A PAPERMAKING FELT WITH ZIG-ZAG PATTERNED CROSS MACHINE YARNS [72] inventor: Howard M. Helland, Appleton, Wis.

[73] Assignee: Appleton Mills, Appleton, Wis.

[22] Filed: Mar. 14, 1969 [2]] Appl. No.: 807,348

[52] U.S.Cl. ..162/275,26/5l.3, 139/383 A, 7 162/381, 162/DlG. l [51] Int. Cl. ..D21f 7/12, D03d 25/00 [58] Field ofSearch ..162/351, 358, 275, 381, DIG. 1; 26/51, 51.3; 139/383 A [56] References Cited UNITED STATES PATENTS 3,383,278 5/1963 l-lelland 3,214,818 11/1965 Ewen ..26/5l Primary ExaminerS. Leon Bashore Assistant Examiner-Richard H. Tushin Attorney-Andrus, Sceales, Starke & Sawall ABSTRACT An endless fabric, such as a papermakers felt, composed of a series of generally parallel warp yarns and having cross machine yams or fibers extending in a zig-zag pattern across the warp yarns. The cross machine yarns in each section of the zig-zag pattern extend at an acute angle up to 80 with respect to a line normal to the warp yarns. The cross machine yarns are stabilized in their zig-zag pattern by physical or chemical means, such as by needling or heat setting, but remain adjustalale thereafter in angularity 'with respect to the warp yarns once installed on a papermaking machine.

15 Claims, 4 Drawing Figures PATENTEDHAR28 1972 3,652,389

2r INVENTOR. !L Howard M. Helland ADJUSTABLE FABRIC FOR USE AS A PAPERMAKING FELT WITH ZIG-ZAG PATTERNED CROSS MACHINE YARNS This invention relates to an endless fabric to be used for filtering operations and more particularly to a papermakers felt for use on a papermaking machine.

In a papermaking machine, the papermakers felt is utilized to pick up or receive a freshly laid web of wet paper after it leaves the forming wire and conducts the paper web to the pressing operation, where additional water is removed from the wet paper web. For effective operation, the highest possible rate of water drainage through the felt and the requisite surface smoothness of the paper being made must be provided and sustained for the longest possible period of time in order to produce the maximum useful felt life. Further, the papermakers felt must have a high degree of dimensional stability and the physical properties of the felt must be uniform throughout its dimensions so that the paper is uniform in quality and finish.

U.S. Pat. No. 3,383,278 is directed to an improved papermakers felt in which the cross machine yarns or fibers are located at an acute angle with respect to the warp or longitudinal yarns, and can be adjusted in angularity when the felt is on the papermaking machine to vary the drainage rate of the felt as well as the finish characteristics of the paper.

The present invention is directed to an improvement to the fabric shown in U.S. Pat. No. 3,383,278. In accordance with the invention, the endless fabric, such as a papermakers felt, is composed of a series of generally parallel warp yarns or strands and a series of cross machine yarns or fibers extend in a zig-zag pattern across the warp yarns. The cross machine yarns are generally parallel to to each other, and in each section of the zig-zag pattern, extend at an acute angle up to 80 with respect to a line normal to the warp yarns.

The zig-zag pattern of the cross yarns provides definite advantages over a construction in which the cross yarns extend diagonally at a constant angle across the width of the fabric. The zig-zag pattern produces adynamically balanced construction by causing any sidewise thrust component of the diagonal yarn configuration to be cancelled by equal and opposite thrusts in the adjoining sections of the zig-zag pattern, thereby improving tracking and the running stability of the fabric.

The zig-zag pattern of the cross machine yarns also makes it possible to obtain a relatively high angular displacement of the cross machine yarns within a relatively short machinedirection length of the fabric. This enables all portions of each cross yarn to be located in the same draw, meaning that during given times during operation all portions of each cross yarn will be located in the space or draw between adjacent rolls and this improves the operating stability of the fabric.

As the cross yarns are all disposed at an acute angle with respect to a line normal to the warp yarns, the holes or pores between the fibers are generally parallelogram shaped and this provides additional advantages. For example, in the nip of a papermachine press, the passage of water from the paper sheet through the felt is necessarily through the felt and backward from the pressure point of the nip for felts of conventional construction. With the fabric of the invention, all portions of the cross yarns are located at an acute angle with respect to the warp yarns, so that at any given time, a series of cross yarns rather than a single cross yarn will be located under the nip. Thus, there will always be a series of openings or water passageways under the nip at any given instant and this characteristic of the fabric, although still favoring the backward drainage vector, also provides forward drainage and results in improved overall drainage characteristics for the fabric.

Further, as the cross yarns in each diagonal section are located at an acute angle with respect to the warp yarns, a series of cross yarns will at any given instant engage the pressure member and this substantially reduces the abrasion of the cross yarns as compared to a normal papermakers felt in which each individual cross yarn strikes broadside against the pressure member.

The zig-zag configuration of the cross yarns of the invention has the further advantage in that it guarantees a greater maximum finish level than is possible with the conventional papermakers felt. Spun yarn varies in diameter along its length and from bobbin-to-bobbin there is a significant variation in diameter. These variations in diameter are transferred to the paper sheet at'the pressure point of the nip. When the nip passes beneath the cross yarns, which are substantially in the same line as the nip in the conventional papermaker's felt, an absolute transfer to the paper sheet of the varying yarn diameters is obtained. With the zig-zag disposition of the cross yarns in the felt of the invention, a series of cross yarns are under the nip line at any given instant and this tends to average out the inherent variations in diameter in the yarns and promotes improved finish in the paper sheet.

Due to the zig-zag configuration of the cross yarns, the

openings between yarns have a parallelogram shape rather than a rectangular shape as found in felts of conventional construction. The parallelogram shaped openings are elongated in a longitudinal direction, providing for a flow of expressed water in the longitudinal direction through the felt and as a result, minimizing potentially destructive longitudinal flow of water through the newly formed paper web. Accordingly, greater nip pressures and higher operating speeds than those possible with felts of conventional construction can be utilized.

The zig-zag pattern provides a high degree of crossdirection or lateral elasticity for the fabric, and as a feature of the invention, the felt, while on the machine, can be stretched laterally to thereby spread the warp yarns apart and aid in dislodging contaminates from the openings in the felt.

It is also contemplated that the angularity of the cross yarns or fibers can be adjusted while the felt is on the papermaking machine. By adjusting the angularity of the cross yarns or fibers, the relative size and shape of the openings or passageways between the yarns can be altered to thereby vary the permeability and drainage characteristics of the felt, as well as dislodging contaminants from the openings to thereby prolong the service life of the felt.

Other objects and advantages will appear in the course of the following description.

The drawings illustrate the best mode presently contemplated of carrying out the invention.

In the drawings:

FIG. 1 is a diagrammatic side elevation of a typical press section of a papermaking machine employing a felt of the invention and having a provision for'adjusting the angularity of the cross yarns when the felt is on the machine;

FIG. 2 is a diagrammatic plan view of a portion of a papermaking machine employing a felt of the invention;

FIG. 3 is a view similar to FIG. 2 showing the cross yarns adjusted in angularity with respect to a lone normal to the warp yarns; and

FIG. 4 is an enlarged fragmentary plan view showing the yarn orientation of a portion of the felt of FIG. 2.

The woven fabric 1 of the invention is particularly adaptable for use as a papermakers felt, as illustrated in FIG. 1. The fabric or felt 1 comprises a series of generally parallel warp yarns or strands 2 and cross yarns 3 are interwoven with the warp yarns and are disposed in a generallyzig-zag configuration.

The yarns 2 and 3 can be formed of any fibrous monofilamentor multifilament material. For example, the yarns 2 and 3 may be composed of animal fibers such as wool; vegetable fibers such as cotton; mineral fibers such as glass; synthetic fibers such as Dacron, Orlon, rayon or nylon; or metal fibers such as steel wire.

Depending on the nature of the fabric and its ultimate use, mixtures or blends of the above fibers can also be employed. When the invention is utilized as a papermakers felt, wool fibers, synthetic fibers or blends thereof are commonly used.

The fabric or felt 1, can be woven in endless form or alternately a straight length of felt can be hand spliced by conventional techniques to provide the endless form. Following splicing, or if the felt is woven in endless form, sections of the felt are cocked or skewed, resulting in the cross yarns 3 being moved to the zig-zag configuration as shown in FIG. 2. The manner of cocking lengthwise sections of the felt to provide the zig-zag configuration is not critical to the invention and any method can be employed which will adjust the angularity of the cross yarns with respect to the warp yarns in the desired pattern. The zig-zag pattern can be formed manually by retarding or advancing the felt at specific points, or by a mechanical system or surface speed variation, or machine direction length control at selected points across the felt width.

The cross yarns are composed of a series of diagonally extending sections 4, 5, 6, and 7 and each section extends at an angle up to 80 with respect to a line normal to the warp yarns, and generally at an angle of 10 to 80 with an angle of about 30 to 60 being preferred. In the uncocked state the openings or spaces between the strands 2 and 3 are generally rectangular in shape, while after cocking to provide the zig-zag pattern, as shown in FIG. 4, the openings between the strands have an elongated parallelogram shape. The sections 4-7 of the cross yarns need not be at the same angle with respect to a line normal to the warp yarns but can be at different angles as long as the angularity falls within the above mentioned range. Further, the sections 4-7 do not necessarily have to extend across the same portion of the width of the felt but the sections can extend across different portions of the felt width. However, it is preferred from the dynamic balance standpoint to maintain the angularity and the diagonal length of the yarn sections 4-7 approximately the same so that the zig-zag configuration will be symmetrical.

After cocking to provide the zig-zag pattern, the felt is stabilized according to conventional procedures. During stabilization the cocked felt is subjected to one or more physical and/or chemical treatments which reduce the tendency of the felt to return to its original uncocked yarn orientation. Various methods can be used to stabilize the felt and the procedures to be employed are generally determined by the composition of the felt and the ultimate use of the felt in the papermaking process. Stabilization for example, can be achieved by needling, heat setting, chemical setting or by hat and moisture fulling. In any case, the stabilization is usually carried out only to a degree which, after stabilization, will still permit free angular adjustment of the cross yarns with respect to the warp yarns.

The fabric when used as a papermakers felt, can be installed on a press of a typical papermaking machine as illustrated in FIG. 1. The endless felt is supported for movement on a series of rolls 8, 9, l0, ll, 12 and 13. After the felt leaves roll 13, a wet web of newly formed paper 14 is transferred from the Fourdrinier wire, not shown, to the upper surface of the felt and the felt and the wet web of paper 14 pass between a pair of rolls l and 16 where the roll pressure serves to extract water from the paper web. The partially dried paper sheet is then transferred from the felt to a second felt, not shown, which carries the partially dried paper web to further drying.

As shown in FIGS. 2 and 3, a conventional marker or guide line 17, is applied to the felt and extends normal to the side edges of the felt. The angularity of the cross yarn sections is indicated by the dashed lines in FIGS. 2 and 3.

In some instances, it may be desired to adjust the angularity of the cross yarns in the longitudinally extending felt sections, indicated by A, B, C and D in FIGS. 2 and 3, on the papermaking machine. To provide for an adjustment of angularity, the ends of the shaft 18 of one of the rolls 10, are journaled within bearing blocks 19 which are pivotally connected to nuts 20 and jack screws 21 are threaded with nuts 20. By rotation of the jack screws the axis of the roller can be varied in angularity. For example, by selective operation of the jack screws 21, one end of the roll shaft 10 will be advanced while the other end of the roll shaft will be retracted. This angular adjustment of the roll 10, shown exaggerated in FIG. 3 for purposes of illustration, has the effect of causing the warp yarns to travel successively greater distances in each revolution of end less travel of the felt with the resulting reorientation of the cross yarns relative to the warp yarns. When the desired degree of angularity adjustment has been achieved, the adjustable roll 10 can be returned to its original position and the new angularity of the cross yarns is maintained until further adjustment.

In the aforementioned method of adjustment, adjacent longitudinally extending sections of the felt are opened and closed, respectively, as the angularity of the cross yarns-is decreased and increased by adjustment of roll 10 in a given direction. For example, the sections A and C, as shown in FIGS. 2 and 3, are widened and the openings enlarged, while the sections B and D are narrowed and the openings are decreased in size. Thus, through continuous angular adjustment of roll 10, first in one direction and then in the other, the felt structure can be worked" to assist in the dislodging of foreign material.

Upon adjusting the angularity of the cross yarns while the felt is on the machine, foreign material is dislodged from the openings between the strands and this substantially increases the service life of the felt. To provide this cleaning effect, the cross yarn sections 4-7 are generally adjusted through an angle of at least 10 and preferably to an angle of about l0 to 45. After the adjustment is made to change the openness of sections of the felt structure, the felt can be readjusted while on the machine to return the cross yarns to their original an gular disposition so that the finish characteristics of the paper being produced will not be altered.

Uniform opening or closing of the entire felt structure with uniform change in the cross yarn angularity can also be carried out to aid in dislodging foreign material from the felt structure through use of a laterally operating web expansion or contraction device. The lateral web expansion can be accomplished by utilizing one or more bowed rolls, as shown in the drawings, or by use of a device to control the surface speed of the felt at particular locations, as described earlier.

As shown in FIGS. 1-3, rolls 9 and 11 are bowed. The bowed rolls 9 and 11 are a conventional type consisting of a curved non-rotatable shaft, and a series of roll segments are individually mounted for rotation on the shaft. By bending the shaft, the curvature of the rolls 9 and 11 can be varied. The bowed roll 9 is positioned so that the felt 1 approaches the concave surface of the roll and leaves from the convex surface, thereby enlarging the width of the felt and spreading the warp yarns apart. The bowed roll 11 is positioned so that the felt will approach and engage the convex surface of the roll and will be discharged from the concave surface, thereby decreasing the width of the felt and returning the warp yarns to their original position. Thus, in the arrangement shown in the drawings, the width of the felt will be increased as it moves in its path of travel from roll 9 to roll 10 to roll 11 and will be returned to its original width after leaving roll 11.

The zig-zag configuration of the cross yarns 3 provides a high degree of cross-direction elasticity and as the warp yarns spread apart, the cross yarns 3 tend to straighten or lengthen to accommodate the spreading of the warp yarns. This results in a change in shape and size of the openings between the yarns and aids in dislodging contaminates from within the openings. The same action can be achieved using a single bowed roll, but the length of time that the warp yarns will be in the spread position during the cycle of travel of the felt will be considerably less.

To aid in dislodging contaminates when the felt is in the spread position, a series of spray nozzles 22 are mounted on the machine and are positioned to discharge water or a detergent solution on the expanded or spread felt. Suction boxes 23 can be utilized to remove the excess water or detergent solution.

. line normal to the warp yarns, the diagonal cross yarns would extend over a substantial length of the fabric, With this high angular displacement each cross yarn could not at any time during travel of the endless felt be located within the same draw or unsupportedarea of the fabric between rolls. However, with the zig-zag configuration of the felt of the invention, the various sections 4-7 of the cross yarns can be disposed at a relatively high angular displacement and yet each cross yarn will extend within a relatively short length of the fabric, so that each cross yarn can be located, at given times during the travel of the endless felt, within the same draw, thereby improving the operating stability of the felt. Thus, the invention enables high angular displacement to be used for the cross yarns, with the resulting advantages to be achieved by the elongated pore structure of the fabric, and yet the cross yarns extend only within a relatively short length of the fabric.

As a further advantage, the construction of the invention produces a dynamically balanced construction for an endless fabric by causing any sidewise component of the diagonal yarn configuration to be cancelled by an equal and opposite thrust on the adjoining section of the zig-zag configuration. This aids in tracking and running stability of the endless felt fabric.

The zigzag configuration of the cross yarns provides a high degree of cross-direction elasticity thereby permitting the felt to be stretched laterally to aid in cleaning of the felt.

While the foregoing description has been directed toward woven fabrics containing cross yarns as the predominant cross machine members, it should be understood that the principle involved in the invention applies equally as well to fabrics in which cross machine fibers rather than distinct yarns are the predominant and controlling cross machine members. it is contemplated, for example, that the cross machine members of the felt could comprise predominantly discontinuous fibers oriented substantially in the zig-zag pattern. Thus, the term cross fibers as used in the claims is intended to include fibers in the form of yarns, as well as discontinuous fibers oriented in the cross machine direction, such as produced by needling cross yarns to a degree so that the continuity or integrity of the cross yarns is at least partially destroyed but the fibers remain in a predominently cross machine direction.

While the structure of the invention has particular application as a papermakers felt it is contemplated that the fabric can be used in various other applications. For example, the fabric can be used as a Fourdrinier wire, in-which the cross yarns can be either fixed to the warp yarns or freely adjustable with respect to the warp yarns, or the fabric can be used as a filtering medium to retain particles or objects of a predetermined size, or used to meter or control the flow of fluids or control the intensity of light or other radiant energy.

Various modes of carrying out the invention are contemplated as being within the scope of the following claims particularly pointing out and distinctly claiming the subject matter which is regarded as the invention.

I Claim:

1. A fabric web, comprising a series of straight generally parallel spaced first strands extending generally longitudinally of the web, and a series of generally parallel spaced second strands extending across the width of said web and defining with said first strands a plurality of openings which extend through the web, said second strands having a generally zigzag configuration and each second strand including a first section extending across a first portion of the width of said web and a second section extending across a second portion of the width of said web, said first and second sections being disposed at anangle to each other and said first and second sections both disposed at an acute angle up to 80 with respect to a line normal to said first strands.

. The fabric web of claim 1, wherein said second strands are interwoven with said first strands.

3. The fabric web of claim 1, wherein said second strands are freely adjustable in angularity with respect to said first strands whereby the effective size of said openings can be selectively varied to change the porosity characteristics of said web.

4. The fabric web of claim 1, wherein said acute angle is in the range of to 60.

5. The fabric web of claim 1, in which said openings are generally parallelogram shaped.

6. The web of claim 1, wherein the length of the first section is substantially equal to the length of said second section and the first section and the second section extend at substantially the same acute angle to said line.

7. An endless fabric web for use on a papermaking machine,

' comprising a series of generally parallel warp yarns, and a plurality of cross fibers interwoven with said warp yarns and being freely adjustable in angularity with respect to said warp 'yams, said warp yarns and said cross fibers defining a plurality of openings therebetween, said cross fibers being disposed in a generally zig-zag pattern and composed of a series of sections,

said sections of said cross fibers being disposed at an acute angle up to with respect to a line normal to said warp yarns.

8. The web of claim 7, wherein each section of each series is disposed at an angle with respect to each adjacent section of said series.

9. The web of claim 8, wherein the length of each section is substantially equal to the length of said adjacent sections.

10. In a papermaking-rnachine, an endless fabric web, and support means for supporting the web in endless travel, said web comprising a series of generally parallel spaced first strands extending generally longitudinally of the web, and a series of generally parallel spaced second strands extending across the width of said web and defining with said first strands a plurality of openings which extend through the web, said second strands having a generally zig-zag configuration and each second strand including a first section extending across a first portion of the width of said web and a second section extending across a second portion of the width of said web, said first and second sections of each strand being disposed at an angle to each other and said first and second sections both disposed at an acute angle up to 80 with respect to a line normal to said first strands.

11. The machine of claim 10, and including means for adjusting the angularity of the second strands with respect to the first strands while the web is engaged with said support means.

12. The machine of claim 10, and including means for varying the lateral spacing of said first strands while the web is on the machine to thereby change the size and shape of said openings and aid in dislodging foreign material from said openings, the angular disposition of the first and second sections of said second strands providing a degree of lateral elasticity for the web to enable the lateral spacing of said first strands to be varied.

13. The machine of claim 12, wherein the means for varying the lateral spacing of said first strands comprises a bowed roll to support the web in endless travel.

14. The machine of claim 10, and including means for increasing the lateral spacing of said first strands to increase the width of a portion of the web while the web is on the machine, and cleaning means for dislodging contaminates from said portion of the web.

15. The machine of claim 14, wherein the cleaning means comprising a liquid spray nozzle.

Claims (15)

1. A fabric web, comprising a series of straight generally parallel spaced first strands extending generally longitudinally of the web, and a series of generally parallel spaced second strands extending across the width of said web and defining with said first strands a plurality of openings which extend through the web, said second strands having a generally zig-zag configuration and each second strand including a first section extending across a first portion of the width of said web and a second section extending across a second portion of the width of said web, said first and second sections being disposed at an angle to each other and said first and second sections both disposed at an acute angle up to 80* with respect to a line normal to said first strands.

2. The fabric web of claim 1, wherein said second strands are interwoven with said first strands.

3. The fabric web of claim 1, wherein said second strands are freely adjustable in angularity with respect to said first strands whereby the effective size of said openings can be selectively varied to change the porosity characteristics of said web.

4. The fabric web of claim 1, wherein said acute angle is in the range of 30* to 60* .

5. The fabric web of claim 1, in which said openings are generally parallelogram shaped.

6. The web of claim 1, wherein the length of the first section is substantially equal to the length of said second section and the first section and the second section extend at substantially the same acute angle to said line.

7. An endless fabric web for use on a papermaking machine, comprising a series of generally parallel warp yarns, and a plurality of cross fibers interwoven with said warp yarns and being freely adjustable in angularity with respect to said warp yarns, said warp yarns and said cross fibers defining a plurality of openings therebetween, said cross fibers being disposed in a generally zig-zag pattern and composed of a series of sections, said sections of said cross fibers being disposed at an acute angle up to 80* with respect to a line normal to said warp yarns.

8. The web of claim 7, wherein each section of each series is disposed at an angle with respect to each adjAcent section of said series.

9. The web of claim 8, wherein the length of each section is substantially equal to the length of said adjacent sections.

10. In a papermaking machine, an endless fabric web, and support means for supporting the web in endless travel, said web comprising a series of generally parallel spaced first strands extending generally longitudinally of the web, and a series of generally parallel spaced second strands extending across the width of said web and defining with said first strands a plurality of openings which extend through the web, said second strands having a generally zig-zag configuration and each second strand including a first section extending across a first portion of the width of said web and a second section extending across a second portion of the width of said web, said first and second sections of each strand being disposed at an angle to each other and said first and second sections both disposed at an acute angle up to 80* with respect to a line normal to said first strands.

11. The machine of claim 10, and including means for adjusting the angularity of the second strands with respect to the first strands while the web is engaged with said support means.

12. The machine of claim 10, and including means for varying the lateral spacing of said first strands while the web is on the machine to thereby change the size and shape of said openings and aid in dislodging foreign material from said openings, the angular disposition of the first and second sections of said second strands providing a degree of lateral elasticity for the web to enable the lateral spacing of said first strands to be varied.

13. The machine of claim 12, wherein the means for varying the lateral spacing of said first strands comprises a bowed roll to support the web in endless travel.

14. The machine of claim 10, and including means for increasing the lateral spacing of said first strands to increase the width of a portion of the web while the web is on the machine, and cleaning means for dislodging contaminates from said portion of the web.

15. The machine of claim 14, wherein the cleaning means comprising a liquid spray nozzle.

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