CA1326609C - Dewatering medium for forming of paper sheets - Google Patents
Dewatering medium for forming of paper sheetsInfo
- Publication number
- CA1326609C CA1326609C CA000562146A CA562146A CA1326609C CA 1326609 C CA1326609 C CA 1326609C CA 000562146 A CA000562146 A CA 000562146A CA 562146 A CA562146 A CA 562146A CA 1326609 C CA1326609 C CA 1326609C
- Authority
- CA
- Canada
- Prior art keywords
- forming
- fabric
- strands
- medium
- machine direction
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F1/00—Wet end of machines for making continuous webs of paper
- D21F1/0027—Screen-cloths
- D21F1/0036—Multi-layer screen-cloths
Landscapes
- Paper (AREA)
- Drying Of Solid Materials (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Manufacture Of Macromolecular Shaped Articles (AREA)
- Laminated Bodies (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A multi-layer dewatering medium having on its one side a first surface which constitutes the forming surface of the medium, and on its opposite side a second surface. At least in the machine direction the layer closest to the second surface is made up of strands, said strands abutting in continuous or discontinuous lengths (floats) on the second surface. The longest ones of said lengths (floats) in the machine direction are longer than discontinuous lengths of strands which are repeated in the cross-machine direction and which abut on said second surface.
A multi-layer dewatering medium having on its one side a first surface which constitutes the forming surface of the medium, and on its opposite side a second surface. At least in the machine direction the layer closest to the second surface is made up of strands, said strands abutting in continuous or discontinuous lengths (floats) on the second surface. The longest ones of said lengths (floats) in the machine direction are longer than discontinuous lengths of strands which are repeated in the cross-machine direction and which abut on said second surface.
Description
1 32~60~
BACKGROUND OF THE INVENTION
The subject invention concerns a multi-layer dewatering medium for forming paper sheets. Each layer of the medium comprises polymer material strands at least in the machine direction. These strands may consist o~
S in~erwoven thread material but could also be extruded strands alone or com~ined with woven thread materials.
In the forming of paper sheets two different kinds of techniques are used today. The con~entional and most common technique involves discharging an acqueous suspension of cellulose fibers onto a forming 10 fabric which travels horizontally and in a fla~ condition during the `
forminy phase proper. The water flows through the for~ing fabric and the restricted mesh size of the fabric prevents the fiber material from penetrating into and through the forming fabric. The fibers remain on ~ -the surface of the fabric, evenly distributed thereon, whereas the dewatering elements, such as suction boxes and foils, facilitate the water through-flow. At the end of the flat, horizontal part o~ the -forming fabrîc loop the fibers have formed a continuous fibrous web.
This type of forming ls generally re~ferred to as Fourdrinier forming.
Aocording to the second applied technique a jet of fibrous ; 20 suspension is discharged into the gap between two mo~ing forming elementsat~l~east one~of whlch~consists of~a forming fabricO The ~ater is removed by~the~fo~rming elements whereas the fiber material is retained by sald elements. This ~ype of formation~ls generally referred to as ~win wire -orming.
.
::
. ~
1 32660q ~.
In both forming methods multilayer forming fabrics are generally used as the forming elements. The stability of multi-layer forming fabrics is largely superior to that of single-layer fabrics and particularly in Fourdrinier machines it is desirable to be able to combine a fine-mesh Forming surface layer with a bottom surface layer having sufficient wearability. These properties are difficult to combine in a single-layer fabric. In double-layer forming fabrics the layer closest to ~he material to be formed could be made from a fine-diameter thread material, resulting in a fine mesh density whereas the layer closest to the dewatering elements may be made ~rom a coanser and thus more abrasion-resistant material.
- In the bottom layer of the fabric which is intended to travel in contact with the dewatering elements of the machine, it is also customary to use a weave pattern of a kind which improves the wearability of the fabric.
To improve weara~ility, it is sugges~ed in SE 74 12 722-b to bring . .
the warp knuckles or lengthwise knuckles to a posi~ian in~eriorly of the ::- , - :
weft knuckles, i.e. the trdnsverse knuckles. Thus, it is the latter transverse knuckles which ~orm ~he contacting layer against which ~he 20 dewatering elements exert an a~rasive effect.
Also~EP~0 046 899 dlscloses a double-layer forming fabric the weft -~
ayer~or ~ransverse layer of which forms the outer layer which is in contact with~the dewatering elemènts.~
A number of German Patent Publications describe double-layer forming 25~ fabrics, e.g. DE 30 36 409,~ DE 31 45 385g DE 32 24 187~ DE 42 24 236, 2 ~:
:": :
:: : :
1 32660q DE 33 01 810, DE 33 05 713. From all of these publications it is apparent that the weft or transverse yarn forms the outer layer against which the dewatering elements exert their abrasive effect.
The technique of designing and constructing mul~i-layer ~abrics has always resided in exposing the transverse weft threads on the rear face ~o the abrasive effects. The purpose of the lengthwise threads is to absorb the wire tension and for this reason these threads may be worn only to a limited degree. However, as no load is exerted on the fabric in the transverse direction, abrasion of the transverse threads may continue until close to the wear-through point of these threads before the fabric is considered to be worn out. This is the reason why all modern forming fabrics are manufactured wi~h transverse bottom threads serving as the abrasive medium. Identical structures have also been used in the twin-wire forming method a1though in this case the abrasion is not quite so strong.
~hen the speed of twin-wire machines is increased, minute holes may for- in the paper web at a certain speed level. This has long been~a -; ~ problem in sertain types of twin-wire machines and has reduced the --~: .
production speed of~such machines. A large number of experiments, none of 20~ them success~ul, were made before the conventional fabric structure was . ~
replaced by~the fabric~structure l~n accordance with the ~eachings o~ the ;~
subject inventi~on.~
SUMMARY OF THE::INVENTION
The~dewatering~medium;for~forming paper she~ts in accordance with 25~ the subject~invenh~on~i;s o~f mul~1-layer~type and~con~i~sts of strands of ~ , ~ : , . ~ . ., polymeric material, which medium has on its one side a first surface cons~ituting the forming surface of ~he medium, which sur- face in position of use oF the medium faces the material to be formed, and on its opposite side a second surface. The dewa~ering mediu~ is characterized therein that at least in the machine direction the layer closest to the second surface is made up from strands, that in the machine direction continuous or discontinuous lengths (floats~ of said strands abut on said second surface, that the longest ones of said len~ths of strands in the machine direction are longer than discontinuous lengths (floats) of strands whlch are repeated in the cross-machine direction and which abut 10 on said second face of the medium. ;
The above problem of hole formation in the paper web in twin wire machines ;s entirely eliminated in the ~ewatering medium in accordance with the subject invention and the machine speed may be increased w;thout difficulty. An ana1ysis o~ the reasons For the hole formation found in prior-art technology medium has proved to be that the transverse knuckles, between the forming roller and the separation roller,act as "water wheel buckets" and ~plash water between the separation roller and the fabrics.
.
The water, which is in the form of droplets, is forced through the fabrics by the separatlon roller and into paper sheet, causing holes to O form therein~ At lower machine speeds $he splashing is less pronounced and does not cause any noticeable problems but the splashing increases w1~h increasing machlne speeds.
Once the problem had been solved in twin-wire machines attemps were made ~o find ou~ whether a~correspondi~ng structural change would affect ~ ; ,,., ~
1 3266~
the forming process in Fourdrinier machines. For this reason a forming fabric ~as manufactured in the conventional manner with the abutment knuckles extending transversely. From the same piece of fabric was cut a fabric extending in the other direction, i.e. such that the former ~ransverse abutment knuckles beca~e lengthwise abutment knuckles. Quite unexpectedly, it was found that the paper sheet which was formed on the latter fabric exhibited less marking. Also in this case the elimination of the splashing caused by the "water wheel phenomenon" is believed to be the reason for the improvement. The transverse "water wheel knuckles" ~-splash water back against the rear side of the fabric, thus dis~urbing the paper sheet forming process. The problem will be discussed in full in connection with the following description of the drawing figures.
BRIEF DESCRIPTION OF THE DRAWINGS
. .
The invention will be described in closer detail in the following with reference to the accompanying drawings, wherein Fig. 1 is a general schematical view showing a twin-wire papermaking machine of roll-~ormer type, FigO 2 is a general schematical view showing a Fourdrin;er-type of papermaking machine9 2~ Fig. 3 is a perspective view of a forming medium in the form of a forming fabric comprising two transversely extending thread systems which are interconnected by one lengthwise ex~ending thread system, Fig. 4 ls a plan view of the;bottom face of the forming fabric of Fig~ 3 : .:
~ : , . ~-~ ~ :
1 32660q Fig. 5 is a perspective view of a second forming medium in the form of a forming fabric comprising doub1e thread systems in its lengthwise as well as in its transverse direction, Fig. 6 is a plan view of the bottom face of the forming fabric in accordance with Fig. 5, and Fig. 7 illustrates a forming med;um consisting of an extruded bottom layer on which is superposed a woYen forming layer.
DETAILED DESCRIPTON OF PREFERRED EMBODIMENTS
. .
Fig. 1 illustrates a twin-wire machine 11 of roll-former type.
10 From the head box 12 the fiber stock i5 discharged into the gap between -the upper fabric 13 and the bottom fabric 14. The fabrics 13 and 14 with ' the fiber stock between them i5 carried over part of the cylinder face of a forming roller 15 for removal of the water through the bo~tom fabric 14 down into the vat 16. When the fabrics leave the forming roller 15, the forming process should, in principle, have been completed. The moist paper sheet, still positioned intermediate the two fabrics, is then carried to a separat~on roller 17. When a bot~om fabric 14 of a :
conventional type is used, this system operates without problem up to a certain speed limit. At higher speeds, however, a certain amount of water ~ 20 accompanies the fabric up to the separdtion roller 17. This has proved to - ~ be due ~o the "wa~er wheel bucket ef~ect" of the ~r~nsverse threads on he rear face o~ the bottom fabric 14. These transverse threads "splash"
water against the separatio~ roller 17. When ~he two fabrics move into contact with the face of the separation roller 17, the wa~er droplets on .
25~ the~rear face of the~bottom fabric 14 are forced thr~ugh the fabric 14 ;-~' -~ 3~660q and against ~he paper sheet intermediate the fabrics~ causing minute holes to form in the paper sheet. When the bottom fabric 14 is manufactured in accordance with the invention with predominantly lengthwise extending strands the "water wheel splashing effect" will be eliminated and the rear face of the fabric will be free of water droplets when the two fabrics are carried into contact with the separation roller 17. In case a small amount of water should nevertheless accompany the fabric this water will collect intermediate the lengthwise strands withcut being forced through the fabric and against ~he paper web.
The problem caused by the above "water wheel splashing effect" has ~--been discovered ~nd remedied by the subject invention primarily with -regard to twin-wire machines. However, it has been found that a similar "water wheel splashing effect" may cause problems also in machines of Fourdrinier type. This wlll be explained in the following with reference to Fig. 2. In a Fourdrinier-type of machine 21 an endless fabric 22 travels in a continuous path around a series of rollers. From ~he head box 23 the~s~ock is dlscharged onto a horizontally travelling part of the -~
fabric 22. The pap~r web forming process takes place on this horizontal ~-part of the fabric~loop. The fabrlc 22 travels in contact with dewatering : ~ ~20~ elements~ such as table rolls 24,;foil~s 25 and suction boxes 26. Owing ~o the ~"water~wheel splashing effect" water is thrown în between these elements and~the~form~ng~fabric~Water may then be forced back through the fabric~and~agai;nst~the paper sheet being formed. Thus, the forming - -proces~s~is~disturbed,~ resulting ln marking of ~he paper web.
25~ The for~ing~me~i~u- in~ the f-rm of the forming fabric 30 shown in ~ ~ ~ 7 : ~, 1 32b60~
Fig. 3 consists of one system of threads 32 which extend at right angles to the direction of travel 31 of the fabric and which threads 32 abut on the first surface 33 of the fabric facing the paper web. A second, system of cross-machine direction threads 34 extend in parallel with the system of threads 32 and abut on the secon~ surface 35 of the fabric. A third system of threads 36 extend in the machine direction 31 and at right angles to the systems of cross-machine direction threads 32 and 34, interconnecting the latter in to a weave and alternately running between the first surface 33 facing the paper web and the second surface 35 facing in the opposite direction.
The invention is restricted to the layer closest ~o the second surface 35. As appears from the plan view of Fig. 4 each machine-direction thread 36 extends externally across four consecutive cross-machine direction threads 349 forming discontinuous strand lengths (floats) 37 in the machine direction of the forming medium. Each cross-machine direction thread 34 extends externally across one or two machine-direction threads 36, forming discontînuous short strand lengths i 38 and sligh~ly longer s~rand lengths 39 in the cross-machine direction of the forming fabric.
In accordance with a second embodiment the formin~ fabric 40 ,:
comprises a system of cross-machine directions threads 42 which extend at right angles to ~he direction of travel 41 of the fabric and which system of threads abut on the first surface 43 of the fabric which faces the ~ ~;
paper web being formed. A second system of cross-machine direction threads~44 extend in parallel with the first system of threads 42 and ..
~::
::
, .
:
1 32660q abut on the second surface 45 of the wire. The forming fabric also comprises two systems of threads 46 and 47 which extend in the lengthwise direction of the machine. The system of threads 46 faces the first surface 43 of the fabric and the sys~em of threads 47 faces the second S fabric surface 45.
The plan view of Fig. 6 illustrates the layer of threads which abut on the second surfa~e 45 of the fabric. Each machine-direction khread 47 ex~ends externally across three consecutive cross-machine direction threads 44, forming discontinuous lengths ~floats) of strands 48 in the machine direction 41 of the forming fabric. Each cross-machine direction thread 44 extends externally across only one machine-direction thread 47, forming discontinuous strand lengths tfloats) 49 in the cross-machine direction of the forming medium.
A further embodiment is illustrated in Fig. 7. The forming medium 50 shown in this drawing figure consists of a weave Sl comprising machine direction threads 52 and cross-machine direc~ion ~hreads 53 which, when interwoven, make up the first forming fabric surface 54 which faces the paper web. The o~her side of the fabric exhibits continuous strands 55 .
which are extruded in the machlne direction and which abut on the second surface 56 of the medium. These continuous lengthwise strands may be interconnected by~means of.transversely extending interconnection strands ~ ~ " ~ .:
S7.
The invention is not limited to the embodiments which are llustrated~and~descri~bed herein but a~number of modifications are 25 possible within the scope of the appended claims. Thè invention is ~ :
applicable to other types of dewatering media than weaves, e.g. to a structure comprising a per~orated foil and underlying strands. - -- . .
g ,, .
~.--:
: ,.,:
BACKGROUND OF THE INVENTION
The subject invention concerns a multi-layer dewatering medium for forming paper sheets. Each layer of the medium comprises polymer material strands at least in the machine direction. These strands may consist o~
S in~erwoven thread material but could also be extruded strands alone or com~ined with woven thread materials.
In the forming of paper sheets two different kinds of techniques are used today. The con~entional and most common technique involves discharging an acqueous suspension of cellulose fibers onto a forming 10 fabric which travels horizontally and in a fla~ condition during the `
forminy phase proper. The water flows through the for~ing fabric and the restricted mesh size of the fabric prevents the fiber material from penetrating into and through the forming fabric. The fibers remain on ~ -the surface of the fabric, evenly distributed thereon, whereas the dewatering elements, such as suction boxes and foils, facilitate the water through-flow. At the end of the flat, horizontal part o~ the -forming fabrîc loop the fibers have formed a continuous fibrous web.
This type of forming ls generally re~ferred to as Fourdrinier forming.
Aocording to the second applied technique a jet of fibrous ; 20 suspension is discharged into the gap between two mo~ing forming elementsat~l~east one~of whlch~consists of~a forming fabricO The ~ater is removed by~the~fo~rming elements whereas the fiber material is retained by sald elements. This ~ype of formation~ls generally referred to as ~win wire -orming.
.
::
. ~
1 32660q ~.
In both forming methods multilayer forming fabrics are generally used as the forming elements. The stability of multi-layer forming fabrics is largely superior to that of single-layer fabrics and particularly in Fourdrinier machines it is desirable to be able to combine a fine-mesh Forming surface layer with a bottom surface layer having sufficient wearability. These properties are difficult to combine in a single-layer fabric. In double-layer forming fabrics the layer closest to ~he material to be formed could be made from a fine-diameter thread material, resulting in a fine mesh density whereas the layer closest to the dewatering elements may be made ~rom a coanser and thus more abrasion-resistant material.
- In the bottom layer of the fabric which is intended to travel in contact with the dewatering elements of the machine, it is also customary to use a weave pattern of a kind which improves the wearability of the fabric.
To improve weara~ility, it is sugges~ed in SE 74 12 722-b to bring . .
the warp knuckles or lengthwise knuckles to a posi~ian in~eriorly of the ::- , - :
weft knuckles, i.e. the trdnsverse knuckles. Thus, it is the latter transverse knuckles which ~orm ~he contacting layer against which ~he 20 dewatering elements exert an a~rasive effect.
Also~EP~0 046 899 dlscloses a double-layer forming fabric the weft -~
ayer~or ~ransverse layer of which forms the outer layer which is in contact with~the dewatering elemènts.~
A number of German Patent Publications describe double-layer forming 25~ fabrics, e.g. DE 30 36 409,~ DE 31 45 385g DE 32 24 187~ DE 42 24 236, 2 ~:
:": :
:: : :
1 32660q DE 33 01 810, DE 33 05 713. From all of these publications it is apparent that the weft or transverse yarn forms the outer layer against which the dewatering elements exert their abrasive effect.
The technique of designing and constructing mul~i-layer ~abrics has always resided in exposing the transverse weft threads on the rear face ~o the abrasive effects. The purpose of the lengthwise threads is to absorb the wire tension and for this reason these threads may be worn only to a limited degree. However, as no load is exerted on the fabric in the transverse direction, abrasion of the transverse threads may continue until close to the wear-through point of these threads before the fabric is considered to be worn out. This is the reason why all modern forming fabrics are manufactured wi~h transverse bottom threads serving as the abrasive medium. Identical structures have also been used in the twin-wire forming method a1though in this case the abrasion is not quite so strong.
~hen the speed of twin-wire machines is increased, minute holes may for- in the paper web at a certain speed level. This has long been~a -; ~ problem in sertain types of twin-wire machines and has reduced the --~: .
production speed of~such machines. A large number of experiments, none of 20~ them success~ul, were made before the conventional fabric structure was . ~
replaced by~the fabric~structure l~n accordance with the ~eachings o~ the ;~
subject inventi~on.~
SUMMARY OF THE::INVENTION
The~dewatering~medium;for~forming paper she~ts in accordance with 25~ the subject~invenh~on~i;s o~f mul~1-layer~type and~con~i~sts of strands of ~ , ~ : , . ~ . ., polymeric material, which medium has on its one side a first surface cons~ituting the forming surface of ~he medium, which sur- face in position of use oF the medium faces the material to be formed, and on its opposite side a second surface. The dewa~ering mediu~ is characterized therein that at least in the machine direction the layer closest to the second surface is made up from strands, that in the machine direction continuous or discontinuous lengths (floats~ of said strands abut on said second surface, that the longest ones of said len~ths of strands in the machine direction are longer than discontinuous lengths (floats) of strands whlch are repeated in the cross-machine direction and which abut 10 on said second face of the medium. ;
The above problem of hole formation in the paper web in twin wire machines ;s entirely eliminated in the ~ewatering medium in accordance with the subject invention and the machine speed may be increased w;thout difficulty. An ana1ysis o~ the reasons For the hole formation found in prior-art technology medium has proved to be that the transverse knuckles, between the forming roller and the separation roller,act as "water wheel buckets" and ~plash water between the separation roller and the fabrics.
.
The water, which is in the form of droplets, is forced through the fabrics by the separatlon roller and into paper sheet, causing holes to O form therein~ At lower machine speeds $he splashing is less pronounced and does not cause any noticeable problems but the splashing increases w1~h increasing machlne speeds.
Once the problem had been solved in twin-wire machines attemps were made ~o find ou~ whether a~correspondi~ng structural change would affect ~ ; ,,., ~
1 3266~
the forming process in Fourdrinier machines. For this reason a forming fabric ~as manufactured in the conventional manner with the abutment knuckles extending transversely. From the same piece of fabric was cut a fabric extending in the other direction, i.e. such that the former ~ransverse abutment knuckles beca~e lengthwise abutment knuckles. Quite unexpectedly, it was found that the paper sheet which was formed on the latter fabric exhibited less marking. Also in this case the elimination of the splashing caused by the "water wheel phenomenon" is believed to be the reason for the improvement. The transverse "water wheel knuckles" ~-splash water back against the rear side of the fabric, thus dis~urbing the paper sheet forming process. The problem will be discussed in full in connection with the following description of the drawing figures.
BRIEF DESCRIPTION OF THE DRAWINGS
. .
The invention will be described in closer detail in the following with reference to the accompanying drawings, wherein Fig. 1 is a general schematical view showing a twin-wire papermaking machine of roll-~ormer type, FigO 2 is a general schematical view showing a Fourdrin;er-type of papermaking machine9 2~ Fig. 3 is a perspective view of a forming medium in the form of a forming fabric comprising two transversely extending thread systems which are interconnected by one lengthwise ex~ending thread system, Fig. 4 ls a plan view of the;bottom face of the forming fabric of Fig~ 3 : .:
~ : , . ~-~ ~ :
1 32660q Fig. 5 is a perspective view of a second forming medium in the form of a forming fabric comprising doub1e thread systems in its lengthwise as well as in its transverse direction, Fig. 6 is a plan view of the bottom face of the forming fabric in accordance with Fig. 5, and Fig. 7 illustrates a forming med;um consisting of an extruded bottom layer on which is superposed a woYen forming layer.
DETAILED DESCRIPTON OF PREFERRED EMBODIMENTS
. .
Fig. 1 illustrates a twin-wire machine 11 of roll-former type.
10 From the head box 12 the fiber stock i5 discharged into the gap between -the upper fabric 13 and the bottom fabric 14. The fabrics 13 and 14 with ' the fiber stock between them i5 carried over part of the cylinder face of a forming roller 15 for removal of the water through the bo~tom fabric 14 down into the vat 16. When the fabrics leave the forming roller 15, the forming process should, in principle, have been completed. The moist paper sheet, still positioned intermediate the two fabrics, is then carried to a separat~on roller 17. When a bot~om fabric 14 of a :
conventional type is used, this system operates without problem up to a certain speed limit. At higher speeds, however, a certain amount of water ~ 20 accompanies the fabric up to the separdtion roller 17. This has proved to - ~ be due ~o the "wa~er wheel bucket ef~ect" of the ~r~nsverse threads on he rear face o~ the bottom fabric 14. These transverse threads "splash"
water against the separatio~ roller 17. When ~he two fabrics move into contact with the face of the separation roller 17, the wa~er droplets on .
25~ the~rear face of the~bottom fabric 14 are forced thr~ugh the fabric 14 ;-~' -~ 3~660q and against ~he paper sheet intermediate the fabrics~ causing minute holes to form in the paper sheet. When the bottom fabric 14 is manufactured in accordance with the invention with predominantly lengthwise extending strands the "water wheel splashing effect" will be eliminated and the rear face of the fabric will be free of water droplets when the two fabrics are carried into contact with the separation roller 17. In case a small amount of water should nevertheless accompany the fabric this water will collect intermediate the lengthwise strands withcut being forced through the fabric and against ~he paper web.
The problem caused by the above "water wheel splashing effect" has ~--been discovered ~nd remedied by the subject invention primarily with -regard to twin-wire machines. However, it has been found that a similar "water wheel splashing effect" may cause problems also in machines of Fourdrinier type. This wlll be explained in the following with reference to Fig. 2. In a Fourdrinier-type of machine 21 an endless fabric 22 travels in a continuous path around a series of rollers. From ~he head box 23 the~s~ock is dlscharged onto a horizontally travelling part of the -~
fabric 22. The pap~r web forming process takes place on this horizontal ~-part of the fabric~loop. The fabrlc 22 travels in contact with dewatering : ~ ~20~ elements~ such as table rolls 24,;foil~s 25 and suction boxes 26. Owing ~o the ~"water~wheel splashing effect" water is thrown în between these elements and~the~form~ng~fabric~Water may then be forced back through the fabric~and~agai;nst~the paper sheet being formed. Thus, the forming - -proces~s~is~disturbed,~ resulting ln marking of ~he paper web.
25~ The for~ing~me~i~u- in~ the f-rm of the forming fabric 30 shown in ~ ~ ~ 7 : ~, 1 32b60~
Fig. 3 consists of one system of threads 32 which extend at right angles to the direction of travel 31 of the fabric and which threads 32 abut on the first surface 33 of the fabric facing the paper web. A second, system of cross-machine direction threads 34 extend in parallel with the system of threads 32 and abut on the secon~ surface 35 of the fabric. A third system of threads 36 extend in the machine direction 31 and at right angles to the systems of cross-machine direction threads 32 and 34, interconnecting the latter in to a weave and alternately running between the first surface 33 facing the paper web and the second surface 35 facing in the opposite direction.
The invention is restricted to the layer closest ~o the second surface 35. As appears from the plan view of Fig. 4 each machine-direction thread 36 extends externally across four consecutive cross-machine direction threads 349 forming discontinuous strand lengths (floats) 37 in the machine direction of the forming medium. Each cross-machine direction thread 34 extends externally across one or two machine-direction threads 36, forming discontînuous short strand lengths i 38 and sligh~ly longer s~rand lengths 39 in the cross-machine direction of the forming fabric.
In accordance with a second embodiment the formin~ fabric 40 ,:
comprises a system of cross-machine directions threads 42 which extend at right angles to ~he direction of travel 41 of the fabric and which system of threads abut on the first surface 43 of the fabric which faces the ~ ~;
paper web being formed. A second system of cross-machine direction threads~44 extend in parallel with the first system of threads 42 and ..
~::
::
, .
:
1 32660q abut on the second surface 45 of the wire. The forming fabric also comprises two systems of threads 46 and 47 which extend in the lengthwise direction of the machine. The system of threads 46 faces the first surface 43 of the fabric and the sys~em of threads 47 faces the second S fabric surface 45.
The plan view of Fig. 6 illustrates the layer of threads which abut on the second surfa~e 45 of the fabric. Each machine-direction khread 47 ex~ends externally across three consecutive cross-machine direction threads 44, forming discontinuous lengths ~floats) of strands 48 in the machine direction 41 of the forming fabric. Each cross-machine direction thread 44 extends externally across only one machine-direction thread 47, forming discontinuous strand lengths tfloats) 49 in the cross-machine direction of the forming medium.
A further embodiment is illustrated in Fig. 7. The forming medium 50 shown in this drawing figure consists of a weave Sl comprising machine direction threads 52 and cross-machine direc~ion ~hreads 53 which, when interwoven, make up the first forming fabric surface 54 which faces the paper web. The o~her side of the fabric exhibits continuous strands 55 .
which are extruded in the machlne direction and which abut on the second surface 56 of the medium. These continuous lengthwise strands may be interconnected by~means of.transversely extending interconnection strands ~ ~ " ~ .:
S7.
The invention is not limited to the embodiments which are llustrated~and~descri~bed herein but a~number of modifications are 25 possible within the scope of the appended claims. Thè invention is ~ :
applicable to other types of dewatering media than weaves, e.g. to a structure comprising a per~orated foil and underlying strands. - -- . .
g ,, .
~.--:
: ,.,:
Claims (3)
1. An improved multi-layer dewatering medium for forming paper sheets, said medium comprising strands of a polymeric material, said medium having a first surface on its one side, said first surface constituting the forming surface of said medium and, in position of use of said medium, facing the material to be formed, and a second surface on its opposite side, the improvement comprising strands forming the layer closest to said second surface at least in the machine direction, continuous or discontinuous lengths (floats) of said strands abutting on said second surface in the machine direction, the longest ones of said lengths (floats) in the machine direction being longer than discontinuous lengths (floats) of strands which are repeated in the cross-machine direction and which abut on said second surface.
2. An improved multi-layer dewatering medium as claimed in claim 1, wherein said strands of polymeric material consist of thread material.
3. An improved multi-layer dewatering medium as claimed in claim 1, wherein said strands of polymeric material are extruded strands.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE8701205-0 | 1987-03-24 | ||
| SE8701205A SE460125B (en) | 1987-03-24 | 1987-03-24 | MULTIPLE STORED DRAINAGE BAND FOR PAPER SHEET STRENGTH |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1326609C true CA1326609C (en) | 1994-02-01 |
Family
ID=20367951
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000562146A Expired - Fee Related CA1326609C (en) | 1987-03-24 | 1988-03-22 | Dewatering medium for forming of paper sheets |
Country Status (12)
| Country | Link |
|---|---|
| EP (1) | EP0284575B1 (en) |
| JP (1) | JPS63295787A (en) |
| AT (1) | ATE64964T1 (en) |
| AU (1) | AU612138B2 (en) |
| BR (1) | BR8801159A (en) |
| CA (1) | CA1326609C (en) |
| DE (1) | DE3863453D1 (en) |
| ES (1) | ES2023015B3 (en) |
| FI (1) | FI90361C (en) |
| MX (1) | MX168766B (en) |
| NO (1) | NO168840C (en) |
| SE (1) | SE460125B (en) |
Families Citing this family (18)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5360518A (en) * | 1991-12-18 | 1994-11-01 | Albany International Corp. | Press fabrics for paper machines |
| US5518042A (en) * | 1994-09-16 | 1996-05-21 | Huyck Licensco, Inc. | Papermaker's forming fabric with additional cross machine direction locator and fiber supporting yarns |
| US5983953A (en) * | 1994-09-16 | 1999-11-16 | Weavexx Corporation | Paper forming progess |
| US5709250A (en) * | 1994-09-16 | 1998-01-20 | Weavexx Corporation | Papermakers' forming fabric having additional fiber support yarns |
| US5937914A (en) * | 1997-02-20 | 1999-08-17 | Weavexx Corporation | Papermaker's fabric with auxiliary yarns |
| US5967195A (en) * | 1997-08-01 | 1999-10-19 | Weavexx Corporation | Multi-layer forming fabric with stitching yarn pairs integrated into papermaking surface |
| US6112774A (en) * | 1998-06-02 | 2000-09-05 | Weavexx Corporation | Double layer papermaker's forming fabric with reduced twinning. |
| DE19859581A1 (en) * | 1998-12-22 | 2000-06-29 | Voith Fabrics Heidenheim Gmbh | Multi-layer paper machine screen for dewatering and sheet formation |
| US6123116A (en) * | 1999-10-21 | 2000-09-26 | Weavexx Corporation | Low caliper mechanically stable multi-layer papermaker's fabrics with paired machine side cross machine direction yarns |
| US6179013B1 (en) | 1999-10-21 | 2001-01-30 | Weavexx Corporation | Low caliper multi-layer forming fabrics with machine side cross machine direction yarns having a flattened cross section |
| US6585006B1 (en) | 2000-02-10 | 2003-07-01 | Weavexx Corporation | Papermaker's forming fabric with companion yarns |
| US6244306B1 (en) | 2000-05-26 | 2001-06-12 | Weavexx Corporation | Papermaker's forming fabric |
| US6253796B1 (en) | 2000-07-28 | 2001-07-03 | Weavexx Corporation | Papermaker's forming fabric |
| US6745797B2 (en) | 2001-06-21 | 2004-06-08 | Weavexx Corporation | Papermaker's forming fabric |
| WO2006020414A1 (en) * | 2004-08-04 | 2006-02-23 | Albany International Corp. | Warp-runner triple layer fabric with paired intrinsic warp binders |
| US20090183795A1 (en) | 2008-01-23 | 2009-07-23 | Kevin John Ward | Multi-Layer Papermaker's Forming Fabric With Long Machine Side MD Floats |
| US7766053B2 (en) | 2008-10-31 | 2010-08-03 | Weavexx Corporation | Multi-layer papermaker's forming fabric with alternating paired and single top CMD yarns |
| US8251103B2 (en) | 2009-11-04 | 2012-08-28 | Weavexx Corporation | Papermaker's forming fabric with engineered drainage channels |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE533696A (en) * | ||||
| US4423755A (en) * | 1982-01-22 | 1984-01-03 | Huyck Corporation | Papermakers' fabric |
| US5114777B2 (en) * | 1985-08-05 | 1997-11-18 | Wangner Systems Corp | Woven multilayer papermaking fabric having increased stability and permeability and method |
| DE8522823U1 (de) * | 1985-08-08 | 1986-12-11 | Birke, Josef, 6780 Pirmasens | Brandsohlenloser Schuh |
| JPS6359111A (en) * | 1986-08-29 | 1988-03-15 | Hitachi Ltd | Comparator and d/a converter |
-
1987
- 1987-03-24 SE SE8701205A patent/SE460125B/en not_active IP Right Cessation
-
1988
- 1988-02-22 AT AT88850058T patent/ATE64964T1/en not_active IP Right Cessation
- 1988-02-22 ES ES88850058T patent/ES2023015B3/en not_active Expired - Lifetime
- 1988-02-22 DE DE8888850058T patent/DE3863453D1/en not_active Expired - Fee Related
- 1988-02-22 EP EP88850058A patent/EP0284575B1/en not_active Expired - Lifetime
- 1988-03-15 NO NO881141A patent/NO168840C/en not_active IP Right Cessation
- 1988-03-15 BR BR8801159A patent/BR8801159A/en not_active IP Right Cessation
- 1988-03-18 FI FI881285A patent/FI90361C/en not_active IP Right Cessation
- 1988-03-22 CA CA000562146A patent/CA1326609C/en not_active Expired - Fee Related
- 1988-03-23 JP JP63069216A patent/JPS63295787A/en active Pending
- 1988-03-23 MX MX010859A patent/MX168766B/en unknown
- 1988-03-24 AU AU13587/88A patent/AU612138B2/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| MX168766B (en) | 1993-06-07 |
| NO168840B (en) | 1991-12-30 |
| SE8701205D0 (en) | 1987-03-24 |
| NO881141L (en) | 1988-09-26 |
| FI90361B (en) | 1993-10-15 |
| EP0284575B1 (en) | 1991-07-03 |
| EP0284575A1 (en) | 1988-09-28 |
| JPS63295787A (en) | 1988-12-02 |
| FI90361C (en) | 1994-01-25 |
| NO881141D0 (en) | 1988-03-15 |
| ATE64964T1 (en) | 1991-07-15 |
| SE8701205L (en) | 1988-09-25 |
| AU1358788A (en) | 1988-09-22 |
| NO168840C (en) | 1992-04-08 |
| ES2023015B3 (en) | 1991-12-16 |
| AU612138B2 (en) | 1991-07-04 |
| FI881285A0 (en) | 1988-03-18 |
| SE460125B (en) | 1989-09-11 |
| BR8801159A (en) | 1988-10-18 |
| FI881285A (en) | 1988-09-25 |
| DE3863453D1 (en) | 1991-08-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |