CA1318165C

CA1318165C - Base fabric structures for seamed wet press felts

Info

Publication number: CA1318165C
Application number: CA000596821A
Authority: CA
Inventors: Patrick H. Penven
Original assignee: Asten Inc
Current assignee: AstenJohnson Inc
Priority date: 1987-10-14
Filing date: 1989-04-14
Publication date: 1993-05-25
Anticipated expiration: 2010-05-25
Also published as: US4824525A

Abstract

ABSTRACT OF THE DISCLOSURE

A papermaker's wet press felt is formed from a flat woven base fabric having the crimped warp yarns of the fabric weave oriented in the lengthwise machine running direction. The warp yarns are formed into seaming loops at the ends of the base fabric which are joined so as to form an endless felt. At least one layer of non-woven batt material is affixed to the base fabric, typically by needling. The flat woven base fabric includes from at least 30 to 50 machine direction, crimped warp yarns per inch for a single layer weave and at least 60 to 100 machine direction, crimped warp yarns per inch for a multi-layer weave.

Description

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IMPROVED BASE F~BRIC STR~cTURES POR SE~MED ~ET PRESS FE~TS

3~C~GRO~
In the manu~acturing o~ paper, papermaker'~ machines are employed which typically oo~prise a ~orming ~ect$on, a press section and a dryer section. The thre2 sactions o~ a typical papermaker's maohine sequentially re~oYe water ~rom a pap~r ~urnish to rorm a paper sheet. In the ~orming section, the ~urnish, compri~ing about 75 to 80 perc2nk by wei~ht wat~r, is deposited on a ~oving ~orming wire, and water is dxalned through the wir~ to ~orm a still w~t paper web or sheet. ~n the press section, the wet web, carried by a wet pr~ss felt, passes ~hrough one or more rollQr nips to ~uxther r~ve wat~r. In ~he final dryer section, ~h~ ~eb, oriented on a drye~ ~elt, ls p~ssed against stezm heated cylinders to rOxm a rinal sheet.
15Th~ S~lts o~ b~lts ~mployed to transport ~h~ Surnish and web th~ough the paper~aking machine ~u t be particularly adapted - to accs~odate ~he unique conditions encou~tered Ln the v~rious secti~ns o~ the paparmaking machine. Du~ to the dif~erence in operating condi~ions betw~en the sections ! the ~elts for each saction ar~ ge~srally ma~ufactured to speci~ic design para~ters.
In the ~et pr~ss section, wh~re a large pa~c~ntage o~ ~he water is remo~ed, ~ha p~spertie~ o~ the ~elt ar~ critical to the e~ricient op~ration o~ the pap~rmaking ~achi~e. ~he ~at~rials and Const~uGtion of a typical ~et press ~elt hav~ evolved as paper~aking machin~s hav~ been i~proved. ~urren~ly, papermaking ~achines may operate at speeds o~ up to 4,000 to 5,000 ~eet per 1 3 ~

minute. A WQt press f~l~ must be capa~le o~ operating continuously at such speeds while providing ~or ~aximum d~ying in order to minimize energy requiremQnts in the dryer section and to minimize breakage o~ the sheet (sheet strength increases as the water content o~ the sheat decreases). Addltionally, the felt must have a sufficient lif~ to ~inimize costly do~n time o~ the machine for felt replacement. Currently, a s~andard ~et press felt comprises a woven ~abric base, either single or multi-ply, to which i5 a~fixed at least one layer o~ bakt ~aterial comprising non-woven ~ibers~ Typically, the batt layer is af~ixed to the fabric base by needllng, an operat$on well known to a person o~
ordinary skill in the art~ A variety of other constructions are someti~e~ employed to for~ wet press felts such as non-woven ~elts or felts having la~inated layers.
The base ~abric of a wet press ~elt must pxovide sufficient strength to allow high speed, extsnded operation while being resistant to compaction and provide adequate dewatering and air permeahility properties~ Also, the base ~abric is preferably .ormed so as to~hav~ mini~al ~ffects on the smooth surface of the batt layers supported thereon.
Typically, wet press ~elts are woven as endless loops so ~hat changes in overall felt length during the li~e of the felt are minimized. By weaving the ~elts as endless loops, the crlmped warp yarns are oriented in ~he cross-machine direction when the ~elt is actually placed on th~ ~achine.

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Th~s, possibl~ stretchlng o~ th~ fQlts by ~lattening~ the ~abrio crimp is ~inimized. Also, such endless loops a~oid ~arking problem~ associated with seamed ~elts. However, such endless felts are di~ficult to weave and provide with batt lay~rs and are difficult to install on papermaking ~achin s.
Generally, the industry ha~s not employed a ~et press felt which is woven flat and ~oined by a seam. In a t~pi~al flat wsven fabric joinQd by a seam into an .endless ~elt, the machine-direction warp yarns are crimped during weaving. The elastic ~ffect in such a felt, coupled with tha possibility o~
product ~arking and weaXness o~ the seam, are believed to have rasulted in a general lack of US2 0~ seamed felt~ as wet press felts.
The ~et press felt o~ the present in~entlon is an impro~ed wet press felt which is easier and more economical to ~orm. Ins~allakion in a typical papermaking mach~ne requires less do~n time due o the use of a seam, and the present invention provides a wet press ~elt which exhibits good operating life and physical propert~es.
~UMMA~Y OF THE INVENTIoN
The wet press ~elt of the present invention comprises a papermaXing machine felt having a woven base fabric wi~h the crimped warp yarns oriented lengthwise in the machine diraction.
The warp yarns aro for~d into ~eaming loops at the ~nds therQof and the felt is ~ormed into a endless loop. The fabric base has a~fixed ther~to, generally by needling, at least on~ layer o~

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non-woven batt material. The batt material not only provides a smooth ~orming Rurface, but also helps to control elastic de~ormation o~ the base fabric in the machine direction.
orientation of the crimped warp yarns in the machine direction 5 when the ~lat woven felt is formed into an endless loop, allows a higher machine direction yarn count than prior art wet press ~elts.
The pr~sent inventlon also i~cludes a method of ~orming a wet press ~elt ~or a papermaker's mach$ne which comprises weaving a flat ~abric bas~ with ~he crimped warp yarns extending lengthwise in ~he machin~ direction, ~orming an endless loop by ~oi~ing two ends of the ~abric in a pin seam and fixing at least one bat~ layer thereto.
BRIEF DESCRIETION OF THE_D~AWINGS

Fiqure 1 is a side elevational, cross-sectional ~ew o~ a portion of a ~et ~r~ss fRlt in accordance with the present invention.
Figure 2 i~ a side elevatisnal, cross-sectional ~iew Or a portion o~ an ~lt~rnatQ embodiment of a wet press ~elt o~ ~he present i~ention.
Figure 3 is a side elevational, cross-sectional view of a portion of an alternate embodiment o~ a ~et press felt of the present inv~ntion.
Figuæe 4 i~ a sid~ eLevational, cros~-sectional view o~ a portlon of an alternate embodi~ent o~ a wet presC ~elt o~ the present invention.

~ 3~ 3~ ~5 Figur~ 5 i~ a side Qlevational, cross-sectional ~iew o~ a portion o* an alternatQ embodiment o* a wet press ~elk in accordance with the prPsent invention.
Figure 6 is a side elevational, cross-sectional ~iew o~ a portion o~ an alternate embodime~t o~ a wet press ~elt in accordance with the present invention.
DETAILED DESCRIPr~ON OF THE PREFERRED EMBOD~MENT
Although peci~ic ~or~s o~ th~ in~ention have been selected for illustration in the drawings, and the following description is drawn in specific terms ~or the purpose o~
describing these ~orm~ of the invention, this de~cription is not intended to lLmit ~he scop~ o the invention which is defined in the appended clai~sO In the drawings, æe~erencP numerals ending in the same integer have been used to de~ignate similar elements in consecuti~e drawings.
The present invention is direct~d to a wet press papermaker's fabric which is flat woven and joined at a seam to form an endless loop. ~he wet press elt in~ludes a base fabric in which the crimped warp yar~s are oriented lengt~wise so as to form the loops at the ends o~ the felt to be joined. The term lengthwise refer~ to the longitudinal direction of the flat woven fabric. ~y SQ ori~nt~ng the crimped warp yarns lengthwise when the wet press felt is placed on a papermaker's machine and joined as an endless loop the cri~ped warp yarns extend in the machine running direction. Thi~ orientation of the crimped warp yarns allows a higher ~achine direction yarn count ~or a gi~en yarn 3i e. Yarns counts for the present invention in the machine ~31~

direction can range ~rom about 30 to 50 yarns per inch in a single-layer weave and from about-3~ to 100 yarns per inch ~or a double layer weave. Such high yarns counts prevent mono-stringing, increase the base fa~ric strengthl increase compaction resistance and i:mpxove pressing unifo~ity due to higher elasticity in the nip. The machine direction yarn count o~
the present invention is approximately double a typical prior art wet press ~elt machine direction yarn count 20r a given yarn size. The wet press felt of the present invention, haviny crimped warp yarns oriented ln the ~achine running direction with a batt layer or layers a~fixed there~o has proven to provide a wet press ~elt which is easier to wea~e, has increased seam 3trength, has improved pressing uniformity and sheet dewatsring e~iciency and superior co~paction resi~tance.
Rsferring to figure 1, a wet press felt 10 is shown comprising a plain wea~e bas~ fabric 12 to which a non-woven batt material 14 ls affixed as by needling. The woven b~s~fabric 12 is formed from we~t yarns 15 ~nd warp yarns 16. The woven base ~abric 12 is fa~med in a plain weave pattern, as ~hown, with warp yarns 16 ~o~ed into loops 17 at each end 18 of the felt 10. ~he loops 17 are adapted to intermesh to form a passageway 19 through which pintle 20 is inserted when felt 10 is formed into an endless belt. When the felt 10 is formed into an endless felt, the warp yarns 16 are oriented lengthwise or i~ the machine running direction 22. ~hus, ~he crimp of ~he warp yarns 16 is oriented in the machine dir~ction 22. The warp yarns 16 and we~t yarns 15 may b8 ~ormed fro~ mono~ ~ent or multi-filaments, comprising either ~ 3 ~

synthPtic or natural materials, however, ~onofilaments are pre~erred in the base gabric. The batt material 14 comprises non-woven fibers af~ixed to woven base 12 such as by needling. A
batt layer may be affixed to both sides o~ woven basa ~abric 12, as shown, or a batt layer 14 may be a~ixed to one side o~ the woven base 12 to for~ a working surface 24. ~eedling o~ batt layer 14 to woven base ~abric 12 is generally pre~erred however, other ~ixation methods may be employed. For example, batt layer 14 may include, dispersed therei~, thermoplastic filaments which 10 serve to affix batt layor 14 to woven ~abric base 12 when heated.
Figure 2 illustrates an alternate embodiment o~ a wet press felt in accordance with the present invention. The em~odiment shown in figure 2 comprises batt mat~rial 14 affixed, such as by needling, to a woven bas~ fabriG 32. The warp yarns 36 lS and weft yarns 33 and 35 can be ~ormed from mono or ~ulti-filaments, Gomprising either natural or synthetic materials. The base fabric 32 is flat woven with warp yarns 36 formed into loops 37 at the ends 38 ~ the felt which are ko be ~oined when felt 30 is ~onaed into an erldless loopO The loops 37, at th2 ends to be ~oined, are adapted to intermesh, ~or~ing a passageway 39 through which a pintle 20 is inserted. When ~elt 30 is so ~oined, the crimped waxp yarns 36 extend in the lengthwise or machine direction 22. The base ~abric 32 is woven wi~h warp yarns 36 forming a 2-2 repeat pattern with upper we~t yarns 33 and a 3-1 repeat pattern with lower we~t yarns 35. ~he ~abric is woven on eight harness with ~he upper surface re~lecting a float of 2 and the lo~er sur~ace reflQcting a plain weave, thus ~orming a single-ply, ~ulti-lay~red ~abric. I~ desired, the two sur~aces could be mirrox i~ages. At least one layer o~ non-woven batt material 14 is a~ixed to woven base 32 such as by needling. Th2 batt material may be a~Xixed to both sides o~ the base fabric 32, as shown, or may be af~ixed to one side of th2 woven base 32 to form a working ~urface 34 above top surface 33 o~ the woven base 32.
Flgura 3 illustrate~ an alternat~ embodi~ent o~ the present i~v~ntion~ In figure 3, a wet press ~elt 40 is formed ~rom a ~lat woven base ~abric 42. A non-woven batt material 14 is a~ixed to on~ or both sides of base ~abric 4~. ~ase fabric 42, as shown is ~igure 3 is a 1-3 upper layer with a mirror image 1-3 bottom layer on an 8 harness weave forming a single-ply, multi-layered f~bric. The we~t yarns 4~ and warp yarns 46 ~ay be either mono or multi-~ilaments, natural or syntheti in nature.
Mono~ilaments are pref~rred ~or t~e warp 4~ and weft 45 yar~s o~
the base ~abric 42. The ~ase ~abric 42 is formed with crimped warp yarns 46 extending ln the lengthwise or machine direction 22. ~t ~he ends 48 to be ~oined, warp yarns 46 are for~ed into loops 47. Wh~n ends 48 are mated, intermeshing o~ loops ~7 ~orms a passageway 49 through whieh pintle 20 ~ay be inserted closing the seam. .1 Figur~ i illustrates alternate embodiment of the present invention. The descriptio~ o~ the wet press ~Plt shown in figure 4 is ~he same as ~he desc~iption of the wet press ~elt shown in ~igure 3 with ~he addition of stuf~er yarns 54 oriented within ~he weave of the base ~abric 52. T~e orientation o~ stu~fer yarns 54 1 3 ~ 3 wit~in the weave o~ the base ~abric 52 improves compac~ion resistanc~ o~ the wet press ~elt in the nip, improves void volume and also improves the fixation o~ batt material 14 by needling.
The stuffer yarns 54 are preferably non-mono~ilaments and are more preferably filled or ~lock~d yarns.
Figure 5 illustrates an alternate embodiment o~ the present invention. In figure 5, a ~lat woven base ~abric 62 is interwov~n wi~h a top layar 61 to which at least ona layer of non-woven batt material 14 is a~ixed as by needling. The base ~abric layer 6~ is a 1-3 upper layer with mirror image 1-3 lower layer on an 8 harness weave. The upper and lower w~t yarns, 64a and 65a respectiv~ly and crimped warp yarns 66a o~ base layer 62 are form d ~rom aither mono or ~ulti-~ilaments, comprising syn~hetic or natural ~ib~rs. ~ono~ilam~nt yarns are pre~rred for bo~h ~he we~t 64a and 65a and warp 66a o~ base layer 62. The base fabric lay~r 62 i~ woven with the crimp~d warp yarns 66a extending in the leng~hwis~ or machin~ direction 22 when the wet press felt 60 is formed lnto an endless loop as described below. Th~ top layer 61 i5 wo~en from weft yarns 65b and crimped warp yarns 66b.
Warp yarns 66b of top layer 61 also interweave with upper weft yarns 64a of base layer 62 to connect the layers ~orming a single-ply, multi-layered f~bric. The combined layers are formed into an endless loop by forming loops 67a and 67b from warp yarns 66a and 66b respectively. Bottom loops 67a are formed from the cri~ped warp yarns 66a o~ bottom layer 62 and top loops 67b are formed ~rom crimped warp yarns 66b of top layer 61. The crimped warp yarns 66b and weft yarns 65b of top layer 61 are formed from 1 3 ~1 3 ~

a so~t-filament or spun yarn to provide a cushioned working surface. The ~elt 60 ls ~ormed into an endless loop by interconnecting loops 67a and 67b and inserting pintles 22 in a manner Xnown to a person o~ ordinary skill in the art. Layers o~
non-woven batt material 14 are aX~ixed to the interconnected layers as by needling.
Figure ~ illustrat~s an alternate embodlment o~ the present invention. In ~igure 6, a flat woven ba~Q ~abric 70~)is ~or~ed ~rom a 1-3 upper layer and a mirror imagQ 1-3 lower layer on an 8 harness weave ~orming a single-ply, ~ulti-layered ~abric.
The base ~abric 70 is flat woven ~rom we~t yarns 75b and crimped warp yarns 76b. Bottom layer 70 is provided w$~h end loops 77 formed rrom crimped warp ya~ns 76a. End loops 77 are adapted to be intermeshed, ~orming a passageway 79 through which pintle 20 is inserte~, thereby ~orming an endless loop. When botto~ layer 70 is fo~med ~nto an ~ndless loop, crimped warp yarns 76b are oriented in the ~achine direction. Top layer 71 comprises a 2-2 single layer endless weave~ The endless loop is cut, as at 7~, to allow the wet ~ress felt to be joined at a seam. The warp yarns 76b o~ top layer 71 extend in the cross-machine direction and we~t yarns 75b extend in the lenqthwi~e or machine direct~on 22. Top layer 71 is oriented about bottom layer 72, and thereafter non-woven batt material 14 is affixed thereto as by needling. ~he fixation o~ non-woven batt ~aterial 14 to layer 71 also interco~nect.~ layers 71 and 72 as well as pro~ides the working surrace ~or the we~ press fel~.

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It should ba under~tood that t:he :~oregoing description and drawings o~ the inverltion are not lnt~nded to b~ limlting, but ar~ only ~x~mplary o~ the inYenti~re features ~rhich ar~ de~ined in th~ clai~ns.
Wh~t I claim is:

~1

Claims

1. A papermaker's wet press felt which is rendered endless by intermeshed seaming loops extending from the respective ends of a base fabric of said felt and a pintle inserted in the channel formed by the intermeshed loops, said felt comprising:
a) a multi-ply base fabric flat woven in a selected repeat pattern with crimped loom warp yarns oriented lengthwise in the machine running direction;
(b) said crimped warp yarns being woven in a range of at least 60 to 100 yarns per inch;
(c) each of said seaming loops being a portion of a selected one of said crimped warp yarns of said base fabric which extends beyond the respective end of said woven base fabric and is retained is said base fabric by said selected repeat pattern;
and (d) at least one layer of batt material affixed to said base fabric.

2. The papermaker's wet press felt of claim 1, further comprising a second fabric layer superimposed around said flat woven base fabric.

3. The papermaker's wet press felt of claim 1, wherein said batt material is a non-woven material needled to said base fabric.

4. In combination, an apparatus for dewatering a paper web in the wet press section of a papermaking machine which includes a plurality of rollers through which the web is dewatered, and an improved web supporting pintle seamed press felt in said wet press section, said wet press felt rendered endless by intermeshing seaming loops, extending from the respective ends of a base fabric of said felt, and inserting a pintle in the resulting channel formed by the loops and further comprises of said base fabric being a multi-ply fabric which was flat woven in a selected repeat pattern with crimped warp yarns woven at least 60 to 100 yarns per inch, said crimped warp yarns oriented lengthwise in the loom and further oriented in the felt running direction of said wet press section, each of said seaming loops, at the respective ends of said felt, being a portion of a selected one of said crimped warp yarns of said base fabric which extends beyond the respective end of said woven base fabric and is retained in said base fabric by said selected repeat pattern, said seaming loops extending in the lengthwise or felt running direction when said loops are intermeshed at the seam, and at least one layer of batt material affixed to said base fabric.

5. The combination of claim 4, further comprising a second fabric layer superimposed around said flat woven base fabric.

6. The combination of claim 4, wherein said batt material is a non-woven material needled to said base fabric.

7. A papermaker's wet press felt which is rendered endless by intermeshing seaming loops, extending from respective ends of a base fabric of said felt, and inserting a pintle in the resulting channel formed by the loops, said felt comprising:
(a) the base fabric being a single layer fabric which was flat woven in a selected repeat pattern with a single layer of crimped warp yarns oriented lengthwise in the loom and further oriented in the felt running direction during use on the papermaking machine;
(b) said base fabric having at least 30 to 50 crimp warp yarns per inch;
(c) each of said seaming loops, at the respective ends of said felt, being a portion of a selected one of said crimped warp yarns of said base fabric which extends beyond the respective end of said woven base fabric and is retained in said base fabric by said selected repeat pattern, said seaming loops extending in the lengthwise or felt running direction when said loops are intermeshed at the seam; and (d) at least one layer of batt material affixed to said base fabric.

8. In combination, an apparatus for dewatering a paper web in the wet press section of a papermaking machine which includes a plurality of rollers through which the web is dewatered, and an improved web supporting pintle seamed press felt in said wet press section, said wet press felt rendered endless by intermeshing seaming loops, extending from the respective ends of a base fabric of said felt, and inserting a pintle in the resulting channel formed by the loops and further comprised of said base fabric being a single layer fabric which was flat woven in a selected repeat pattern with a single layer of crimped warp yarns at least 30 to 50 yarns per inch, said crimped warp yarns oriented lengthwise in the loom and further oriented in the felt running direction of said wet press section, each of said seaming loops, at the respective ends of said felt, being a portion of a selected one of said crimped warp yarns of said woven base fabric and is retained in said base fabric by said selected repeat pattern, said seaming loops extending in the lengthwise or felt running direction when said loops are intermeshed at the seam, and at least one layer of batt material affixed to said base fabric.

9. A papermaker's wet press felt which is rendered endless by intermeshing seaming loops, extending from respective ends of a base fabric of said felt, and inserting a pintle in the resulting channel formed by the loops, said felt comprising:
(a) the base fabric being flat woven in a selected repeat pattern with N layers, where N is a positive integer, of crimped warp yarns oriented lengthwise in the loom and further oriented in the felt running direction during use on the papermaking machine;
(b) said crimped warp yarns being woven at least 30 N to 60 N yarns per inch;
(c) each of said seaming loops, at the respective ends of said felt, being a portion of a selected one of said crimped warp yarns of said base fabrics which extends beyond the respective end of said woven base fabric and is retained in said base fabric by said selected repeat pattern, said seaming loops extending in the lengthwise or felt running direction when said loops are intermeshed at the seam; and (d) at least one layer of batt material affixed to said base fabric.

10. The papermaker's wet press felt of claim 9 further comprising a second fabric layer superimposed around said flat woven base fabric.

11. The papermaker's wet press felt of claim 9 wherein said batt material is a non-woven material needled to said base fabric.