CA2153846A1 - Process for producing a papermakers' fabric with a smooth surface - Google Patents
Process for producing a papermakers' fabric with a smooth surfaceInfo
- Publication number
- CA2153846A1 CA2153846A1 CA 2153846 CA2153846A CA2153846A1 CA 2153846 A1 CA2153846 A1 CA 2153846A1 CA 2153846 CA2153846 CA 2153846 CA 2153846 A CA2153846 A CA 2153846A CA 2153846 A1 CA2153846 A1 CA 2153846A1
- Authority
- CA
- Canada
- Prior art keywords
- fabric
- machine direction
- process according
- dryer
- heated
- 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.)
- Abandoned
Links
- 239000004744 fabric Substances 0.000 title claims abstract description 110
- 238000000034 method Methods 0.000 title claims abstract description 24
- 238000000465 moulding Methods 0.000 claims abstract description 10
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 239000002759 woven fabric Substances 0.000 claims description 3
- 238000001816 cooling Methods 0.000 claims description 2
- 230000009182 swimming Effects 0.000 claims description 2
- 239000000463 material Substances 0.000 description 6
- 238000012546 transfer Methods 0.000 description 5
- 238000011109 contamination Methods 0.000 description 4
- 238000013461 design Methods 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 239000004952 Polyamide Substances 0.000 description 2
- 239000012736 aqueous medium Substances 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 238000001704 evaporation Methods 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 238000007730 finishing process Methods 0.000 description 2
- 239000002609 medium Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- -1 peek Polymers 0.000 description 2
- 230000035699 permeability Effects 0.000 description 2
- 229920002647 polyamide Polymers 0.000 description 2
- 229920003043 Cellulose fiber Polymers 0.000 description 1
- 229920000742 Cotton Polymers 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 229920013632 Ryton Polymers 0.000 description 1
- 239000004736 Ryton® Substances 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 229920003235 aromatic polyamide Polymers 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000009189 diving Effects 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 229920006149 polyester-amide block copolymer Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 238000010561 standard procedure Methods 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 239000004753 textile Substances 0.000 description 1
- 238000009941 weaving Methods 0.000 description 1
- 210000002268 wool Anatomy 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
- D06C—FINISHING, DRESSING, TENTERING OR STRETCHING TEXTILE FABRICS
- D06C15/00—Calendering, pressing, ironing, glossing or glazing textile fabrics
- D06C15/02—Calendering, pressing, ironing, glossing or glazing textile fabrics between co-operating press or calender rolls
-
- 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
Landscapes
- Engineering & Computer Science (AREA)
- Textile Engineering (AREA)
- Paper (AREA)
Abstract
A process for producing a papermaker' fabric, wherein the paper contacting surface of the fabric is molded between two preferably heated surfaces adapted to apply contact pressure to the fabric to optimally smoothen the paper contacting surface of the fabric and egalize caliper variations in the fabric.
Preferably the two surfaces are surfaces of two cooperating rolls formed in a nip press. The fabric is passed through the nip press into engagement with the heated rolls thereby molding and smoothening the surface of the fabric.
Preferably the two surfaces are surfaces of two cooperating rolls formed in a nip press. The fabric is passed through the nip press into engagement with the heated rolls thereby molding and smoothening the surface of the fabric.
Description
PROCESS FOR PRODUCING A PAP~
FABRIC WITH A SMOOTH SURFACE
FABRIC WITH A SMOOTH SURFACE
2 Field of the Invention
3 The present invention relates to papermakers' fabrics and
4 especially to papermaking fabrics for the dryer or forming sections of a papermaking machine.
7 Bachylo~d of the Invention 8 In the conventional fourdrinier papermaking process, a water 9 slurry or suspension of cellulose fibers, known as the paper "stock", is fed onto the top of the upper run of a travelling 11 endless forming belt. The forming belt provides a papermaking 12 surface and operates as a filter to separate the cellulosic 13 fibers from the aqueous medium from the cellulosic fibers by 14 providing for the drainage of the aqueous medium through its mesh openings, also known as drainage holes, by vacuum means or the 16 like located on the drainage side of the fabric.
17 After leaving the forming medium the somewhat self-18 supporting paper web is transferred to the press section of the 19 machine and onto a press fabric, where still more of its water content is removed by passing it through a series of pressure 21 nips formed by cooperating press rolls, these press rolls serving 22 to compact the web as well.
23 Subsequently, the paper web is transferred to a dryer 24 section where it is passed about and held in heat transfer relation with a series of heated, generally cylindrical rolls to 26 remove still further amounts of water therefrom by evaporation.
27 Dryer fabrics are used in the dryer section of papermaking 28 machinery to support the moist paper web as it encounters the -heated rolls. Typically, the dryer fabric is formed into a 2 conveyor belt-like shape and incorporates at least a woven base 3 fabric with a smooth top surface for contacting the paper web.
The surface of the dryer fabric is determinative of the 6 marking characteristics found on the paper. If the surface of 7 the dryer fabric is smooth, the contact paper web will exhibit 8 less marking, thereby resulting in high quality paper. In 9 addition, a dryer fabric with a uniform and smooth surface provides increased contact area between the web and the heated 11 rolls of the dryer section, thereby increasing the heat transfer 12 between the heated rolls of the dryer section and the paper web 13 and leading to more efficient sheet dewatering.
14 Thus, it has been a goal of the papermaking industry to produce dryer fabrics with a smooth and uniform paper contacting 16 surface. The standard method for producing a dryer fabric with 17 these characteristics has been to provide a high fabric density 18 with weave patterns having long machine or cross machine 19 direction floatings. Another approach has been to form the dryer fabric from flat monofilament materials in the machine direction 21 of the fabric.
22 Despite the attempts of the prior art, however, knuckles 23 formed at the crossing of the machine and cross machine direction 24 yarns invariably render the fabric prone to contamination and marking, and prevent uniformly high heat transfer. Using flat 26 monofilaments has improved the heat transfer between sheet and 27 dryer roll by increasing contact area, but forms large 28 contamination traps according to the shape of the monofilament.
1 Thus, various impurities become trapped within these fabrics 2 causing highly undesirable marking characteristics.
3 These difficulties exist similarly in the production of 4 forming fabrics for the forming section of the papermaking machinery. Forming fabrics, however, generally cannot be 6 manufactured with a high fabric density since large interstices 7 between fabric yarns must exist to ensure drainage of the aqueous 8 medium through the fabric. Thus, surface smoothness is achieved 9 in forming fabrics primarily by providing long floats on the paper contacting surface of the fabric, and by performing various 11 grinding and treating methods. Invariably, however, knuckles 12 formed on the papermaking surface cause the forming fabrics to 13 suffer from the same deficiencies as discussed above in 14 connection with dryer fabrics.
16 Sl~mm~ry of the Invention 17 Therefore, one object of the present invention is to provide 18 an improved papermakers~ fabric for use in the forming or dryer 19 section of the papermaking machine.
Another object of this invention is to provide a 21 papermakers~ fabric having an improved surface, resulting in 22 better sheet quality.
23 Yet another object of the present invention is to provide 24 a papermakers' dryer fabric with an improved drying rate due to improved contact between the paper web and the rolls of the dryer 26 section.
21~38~ G
.
1 Still another object of the present invention is to provide 2 a papermakers~ dryer fabric with less opportunity for 3 contamination due to missing knuckles.
4 These and other objects of the invention are achieved by a process for producing a papermakers~ fabric, wherein the paper 6 contacting surface of the fabric is molded between two preferably 7 heated surfaces adapted to apply contact pressure to the fabric 8 to optimally smoothen the paper contacting surface of the fabric 9 and egalize caliper variations in the fabric. Preferably the two surfaces are the surfaces of two cooperating rolls formed in a 11 nip press. The fabric is passed through the nip press into 12 engagement with the heated rolls thereby molding and smoothening 13 the surface of the fabric.
Brief Description of the Drawing 16 The process for manufacturing fabrics according to the 17 present invention will be apparent from the following detailed 18 description of the invention, along with the drawings, in which 19 like reference numbers refer to like members throughout the various views.
22 FIGS. 1-3 are unity textile design charts for illustrating 23 preferred embodiments of a dryer fabric for use in connection 24 with the present invention.
26 FIGS. 4-8 are machine direction sectional views of preferred 27 embodiments of a forming fabric for use in connection with the 28 present invention.
21538~6 1 FIG. 9 is a diagram of a preferred system for performing a 2 surface molding operation on a papermaker's fabric according to 3 the present invention.
Detailed Description of the Invention 6 Generally, the invention relates to the manufacturing and 7 application of papermaker's fabrics for the forming or dryer 8 sections of a paper machine involving the step of surface molding 9 the fabric between heated surfaces to obtain an optimally uniform paper contacting surface.
11 The fabrics manufactured according to the present invention, 12 as do most papermakers~ fabrics, incorporate a woven fabric, 13 being either single or multilayer, e.g. monoplane, duplex, X-14 weave, triple weft or triplex. The weave patterns and materials for the fabric will be selected according to criteria such as 16 smoothness of the fabric surface against the sheet side and/or 17 wear resistance against the rolls.
18 FIGS. 1-3 are design charts which illustrate preferred weave 19 patterns for dryer fabrics which are particularly useful in connection with the present invention. In these figures, Arabic 21 numerals 1-13 denote cross machine direction yarns, and numerals 22 13-18 denote machine direction yarns. The symbols ''Xll denote 23 locations where cross machine direction yarns are positioned over 24 machine direction yarns, giving long machine direction floats.
FIGS. 4-8 are machine direction sectional views of preferred 26 forming fabrics for us in connection with the present invention 27 wherein the machine direction yarns 19-20 are interwoven with 28 cross machine direction yarns 21-24.
2I$384 6 1 As can be seen, the preferred weaves include long machine 2 direction yarn floats, i.e. machine direction yarns which travel 3 over two or more successive cross machine direction yarns without 4 diving back down into the fabric. FIGS. 1-8 represent preferred, but not limiting weave patterns for dryer and forming 6 fabrics. The fabrics depicted in FIGS. 1-3 demonstrate preferred 7 weaves on either eight or twelve shaft. Different weave patterns 8 are used to match different permeability ranges for the dryer 9 fabrics according to their application in the warm-up, the main evaporation zone, or the cooling zone of the dryer. Similarly, 11 different weave patterns for the forming fabrics may be used 12 according to predetermined criteria.
13 The conventional yarns utilized in dryer and forming fabrics 14 of the present invention will vary, depending upon the desired properties of the fabric. Round shaped polyester-monofilaments 16 with diameters of 0.3mm to 0.6mm represent the preferred material 17 for the standard dryer fabric. Polyester and polyamide 18 monofilaments with diameter of 0.08mm to 0.4mm represent the 19 preferred material for standard forming fabrics. Nonetheless, the yarns may be round, elliptic, or flat, and may be 21 multifilament yarns, monofilament yarns, twisted multifilament 22 and/or monofilament yarns, spun yarns or any combination of the 23 above. It is within the skill of those practicing in the 24 relevant art to select a yarn type, depending on the purpose of the fabric, to utilize with the concepts of the present 26 invention.
27 Yarns selected for use in each layer of the woven dryer or 28 forming fabric of the present invention may be those commonly 21538~6 1 used in dryer fabric or forming fabric base fabric layers. For 2 example, the yarns could be ryton, peek, cotton, wool, 3 polypropylenes, polyesters, aramids or polyamides or combinations 4 of these materials. Again, one skilled in the art will select a yarn material according to the particular application of the 6 final composite fabric.
7 After weaving and joining, the dryer or forming fabrics of 8 the present invention are subjected to a finishing process.
9 Referring to FIG. 9, during the preferred finishing process, the fabric 27 is surface smoothened by molding between two rolls 25, 11 26 configured in a nip press. At least one, preferably both 12 rolls 25,26 are heated by either a steam or oil source (not 13 shown). Also, in the preferred embodiment the rolls 25, 26 are 14 swimming rolls which provide uniform pressure and heat transfer, giving the fabric a uniformly molded surface. In the molding 16 process, the fabric 27 is warmed on a heated roll(s) 25,26, 17 passed through the nip press formed by the rolls, and cooled.
18 This process is iteratively performed while continuously checking 19 caliper, permeability and imprints of the fabric surface to meet desired specifications for the fabric.
21 Different fabric designs require specific molding procedures 22 which differ in temperature, loading, dwell time, passes, etc.
23 to obtain optimum surface smoothness. However, one pass of the 24 fabric between two rolls configured in a nip press at a temperature of 150 C, at a speed of 0.7 m/min and a loading of 26 20-150 kp/cm2 represents a useful starting point. Nonetheless, 27 the optimum parameters will always depend on the type of fabric 28 used and the desired criteria for the final fabric. It has been 1 ~found, however, that the temperature used for the process is 2typically between about 130 C and about 240 C. The speed at 3which the fabric is passed through the rolls varies depending on 4the design between 0.3 and 10 m/min. Likewise, the specific 5loading used for the molding process varies between about 20 6kp/cm2 and 150 kp/cm2. Typically, the fabric must be passed 7through the rolls up to 10 times to meet the desired fabric 8specifications.
9In addition, although the preferred embodiment involves the 10use of two heated rolls 25,26 it is also possible to heat only 11one roll 25 or to use only one roll to press the fabric against 12a flat plate (not shown) with either or both of the surfaces 13being heated. Other variations are also possible as long as 14contact pressure and heat are applied to the fabric between two 15surfaces.
16Thus, the described process provides a molded fabric 17surface having optimum uniformity. In addition, caliper 18variations which exist in prior art fabrics are egalized down to 19the micro-scale and prominent fabric knuckles are eliminated.
20Thus, a fabric having a molded surface according to the present 21invention provides improved paper quality, less contamination, 22and improved drying rates due to improved sheet/roll contact in 23the case of dryer fabrics.
24While the invention has been particularly shown and 25described with reference to the aforementioned embodiments, it 26will be understood by those skilled in the art that various 27changes in form and detail may be made therein without departing 28 from the spirit and scope of the invention. Thus, any 1 modification of the shape, configuration and composition of the 2 elements comprising the invention is within the scope of the 3 present invention. It is to be further understood that the 4 instant invention is by no means limited to the particular constructions or procedures herein disclosed and/or shown in the 6 drawings, but also comprises any modifications or equivalents 7 within the scope of the claims.
7 Bachylo~d of the Invention 8 In the conventional fourdrinier papermaking process, a water 9 slurry or suspension of cellulose fibers, known as the paper "stock", is fed onto the top of the upper run of a travelling 11 endless forming belt. The forming belt provides a papermaking 12 surface and operates as a filter to separate the cellulosic 13 fibers from the aqueous medium from the cellulosic fibers by 14 providing for the drainage of the aqueous medium through its mesh openings, also known as drainage holes, by vacuum means or the 16 like located on the drainage side of the fabric.
17 After leaving the forming medium the somewhat self-18 supporting paper web is transferred to the press section of the 19 machine and onto a press fabric, where still more of its water content is removed by passing it through a series of pressure 21 nips formed by cooperating press rolls, these press rolls serving 22 to compact the web as well.
23 Subsequently, the paper web is transferred to a dryer 24 section where it is passed about and held in heat transfer relation with a series of heated, generally cylindrical rolls to 26 remove still further amounts of water therefrom by evaporation.
27 Dryer fabrics are used in the dryer section of papermaking 28 machinery to support the moist paper web as it encounters the -heated rolls. Typically, the dryer fabric is formed into a 2 conveyor belt-like shape and incorporates at least a woven base 3 fabric with a smooth top surface for contacting the paper web.
The surface of the dryer fabric is determinative of the 6 marking characteristics found on the paper. If the surface of 7 the dryer fabric is smooth, the contact paper web will exhibit 8 less marking, thereby resulting in high quality paper. In 9 addition, a dryer fabric with a uniform and smooth surface provides increased contact area between the web and the heated 11 rolls of the dryer section, thereby increasing the heat transfer 12 between the heated rolls of the dryer section and the paper web 13 and leading to more efficient sheet dewatering.
14 Thus, it has been a goal of the papermaking industry to produce dryer fabrics with a smooth and uniform paper contacting 16 surface. The standard method for producing a dryer fabric with 17 these characteristics has been to provide a high fabric density 18 with weave patterns having long machine or cross machine 19 direction floatings. Another approach has been to form the dryer fabric from flat monofilament materials in the machine direction 21 of the fabric.
22 Despite the attempts of the prior art, however, knuckles 23 formed at the crossing of the machine and cross machine direction 24 yarns invariably render the fabric prone to contamination and marking, and prevent uniformly high heat transfer. Using flat 26 monofilaments has improved the heat transfer between sheet and 27 dryer roll by increasing contact area, but forms large 28 contamination traps according to the shape of the monofilament.
1 Thus, various impurities become trapped within these fabrics 2 causing highly undesirable marking characteristics.
3 These difficulties exist similarly in the production of 4 forming fabrics for the forming section of the papermaking machinery. Forming fabrics, however, generally cannot be 6 manufactured with a high fabric density since large interstices 7 between fabric yarns must exist to ensure drainage of the aqueous 8 medium through the fabric. Thus, surface smoothness is achieved 9 in forming fabrics primarily by providing long floats on the paper contacting surface of the fabric, and by performing various 11 grinding and treating methods. Invariably, however, knuckles 12 formed on the papermaking surface cause the forming fabrics to 13 suffer from the same deficiencies as discussed above in 14 connection with dryer fabrics.
16 Sl~mm~ry of the Invention 17 Therefore, one object of the present invention is to provide 18 an improved papermakers~ fabric for use in the forming or dryer 19 section of the papermaking machine.
Another object of this invention is to provide a 21 papermakers~ fabric having an improved surface, resulting in 22 better sheet quality.
23 Yet another object of the present invention is to provide 24 a papermakers' dryer fabric with an improved drying rate due to improved contact between the paper web and the rolls of the dryer 26 section.
21~38~ G
.
1 Still another object of the present invention is to provide 2 a papermakers~ dryer fabric with less opportunity for 3 contamination due to missing knuckles.
4 These and other objects of the invention are achieved by a process for producing a papermakers~ fabric, wherein the paper 6 contacting surface of the fabric is molded between two preferably 7 heated surfaces adapted to apply contact pressure to the fabric 8 to optimally smoothen the paper contacting surface of the fabric 9 and egalize caliper variations in the fabric. Preferably the two surfaces are the surfaces of two cooperating rolls formed in a 11 nip press. The fabric is passed through the nip press into 12 engagement with the heated rolls thereby molding and smoothening 13 the surface of the fabric.
Brief Description of the Drawing 16 The process for manufacturing fabrics according to the 17 present invention will be apparent from the following detailed 18 description of the invention, along with the drawings, in which 19 like reference numbers refer to like members throughout the various views.
22 FIGS. 1-3 are unity textile design charts for illustrating 23 preferred embodiments of a dryer fabric for use in connection 24 with the present invention.
26 FIGS. 4-8 are machine direction sectional views of preferred 27 embodiments of a forming fabric for use in connection with the 28 present invention.
21538~6 1 FIG. 9 is a diagram of a preferred system for performing a 2 surface molding operation on a papermaker's fabric according to 3 the present invention.
Detailed Description of the Invention 6 Generally, the invention relates to the manufacturing and 7 application of papermaker's fabrics for the forming or dryer 8 sections of a paper machine involving the step of surface molding 9 the fabric between heated surfaces to obtain an optimally uniform paper contacting surface.
11 The fabrics manufactured according to the present invention, 12 as do most papermakers~ fabrics, incorporate a woven fabric, 13 being either single or multilayer, e.g. monoplane, duplex, X-14 weave, triple weft or triplex. The weave patterns and materials for the fabric will be selected according to criteria such as 16 smoothness of the fabric surface against the sheet side and/or 17 wear resistance against the rolls.
18 FIGS. 1-3 are design charts which illustrate preferred weave 19 patterns for dryer fabrics which are particularly useful in connection with the present invention. In these figures, Arabic 21 numerals 1-13 denote cross machine direction yarns, and numerals 22 13-18 denote machine direction yarns. The symbols ''Xll denote 23 locations where cross machine direction yarns are positioned over 24 machine direction yarns, giving long machine direction floats.
FIGS. 4-8 are machine direction sectional views of preferred 26 forming fabrics for us in connection with the present invention 27 wherein the machine direction yarns 19-20 are interwoven with 28 cross machine direction yarns 21-24.
2I$384 6 1 As can be seen, the preferred weaves include long machine 2 direction yarn floats, i.e. machine direction yarns which travel 3 over two or more successive cross machine direction yarns without 4 diving back down into the fabric. FIGS. 1-8 represent preferred, but not limiting weave patterns for dryer and forming 6 fabrics. The fabrics depicted in FIGS. 1-3 demonstrate preferred 7 weaves on either eight or twelve shaft. Different weave patterns 8 are used to match different permeability ranges for the dryer 9 fabrics according to their application in the warm-up, the main evaporation zone, or the cooling zone of the dryer. Similarly, 11 different weave patterns for the forming fabrics may be used 12 according to predetermined criteria.
13 The conventional yarns utilized in dryer and forming fabrics 14 of the present invention will vary, depending upon the desired properties of the fabric. Round shaped polyester-monofilaments 16 with diameters of 0.3mm to 0.6mm represent the preferred material 17 for the standard dryer fabric. Polyester and polyamide 18 monofilaments with diameter of 0.08mm to 0.4mm represent the 19 preferred material for standard forming fabrics. Nonetheless, the yarns may be round, elliptic, or flat, and may be 21 multifilament yarns, monofilament yarns, twisted multifilament 22 and/or monofilament yarns, spun yarns or any combination of the 23 above. It is within the skill of those practicing in the 24 relevant art to select a yarn type, depending on the purpose of the fabric, to utilize with the concepts of the present 26 invention.
27 Yarns selected for use in each layer of the woven dryer or 28 forming fabric of the present invention may be those commonly 21538~6 1 used in dryer fabric or forming fabric base fabric layers. For 2 example, the yarns could be ryton, peek, cotton, wool, 3 polypropylenes, polyesters, aramids or polyamides or combinations 4 of these materials. Again, one skilled in the art will select a yarn material according to the particular application of the 6 final composite fabric.
7 After weaving and joining, the dryer or forming fabrics of 8 the present invention are subjected to a finishing process.
9 Referring to FIG. 9, during the preferred finishing process, the fabric 27 is surface smoothened by molding between two rolls 25, 11 26 configured in a nip press. At least one, preferably both 12 rolls 25,26 are heated by either a steam or oil source (not 13 shown). Also, in the preferred embodiment the rolls 25, 26 are 14 swimming rolls which provide uniform pressure and heat transfer, giving the fabric a uniformly molded surface. In the molding 16 process, the fabric 27 is warmed on a heated roll(s) 25,26, 17 passed through the nip press formed by the rolls, and cooled.
18 This process is iteratively performed while continuously checking 19 caliper, permeability and imprints of the fabric surface to meet desired specifications for the fabric.
21 Different fabric designs require specific molding procedures 22 which differ in temperature, loading, dwell time, passes, etc.
23 to obtain optimum surface smoothness. However, one pass of the 24 fabric between two rolls configured in a nip press at a temperature of 150 C, at a speed of 0.7 m/min and a loading of 26 20-150 kp/cm2 represents a useful starting point. Nonetheless, 27 the optimum parameters will always depend on the type of fabric 28 used and the desired criteria for the final fabric. It has been 1 ~found, however, that the temperature used for the process is 2typically between about 130 C and about 240 C. The speed at 3which the fabric is passed through the rolls varies depending on 4the design between 0.3 and 10 m/min. Likewise, the specific 5loading used for the molding process varies between about 20 6kp/cm2 and 150 kp/cm2. Typically, the fabric must be passed 7through the rolls up to 10 times to meet the desired fabric 8specifications.
9In addition, although the preferred embodiment involves the 10use of two heated rolls 25,26 it is also possible to heat only 11one roll 25 or to use only one roll to press the fabric against 12a flat plate (not shown) with either or both of the surfaces 13being heated. Other variations are also possible as long as 14contact pressure and heat are applied to the fabric between two 15surfaces.
16Thus, the described process provides a molded fabric 17surface having optimum uniformity. In addition, caliper 18variations which exist in prior art fabrics are egalized down to 19the micro-scale and prominent fabric knuckles are eliminated.
20Thus, a fabric having a molded surface according to the present 21invention provides improved paper quality, less contamination, 22and improved drying rates due to improved sheet/roll contact in 23the case of dryer fabrics.
24While the invention has been particularly shown and 25described with reference to the aforementioned embodiments, it 26will be understood by those skilled in the art that various 27changes in form and detail may be made therein without departing 28 from the spirit and scope of the invention. Thus, any 1 modification of the shape, configuration and composition of the 2 elements comprising the invention is within the scope of the 3 present invention. It is to be further understood that the 4 instant invention is by no means limited to the particular constructions or procedures herein disclosed and/or shown in the 6 drawings, but also comprises any modifications or equivalents 7 within the scope of the claims.
Claims (10)
1. A process for manufacturing a papermakers forming fabric or dryer fabric comprising:
providing a woven fabric of interwoven cross machine direction and machine direction yarns; and molding a paper contacting surface of said fabric by passing said fabric between two surfaces adapted to apply contact pressure to said fabric, at least one of said two surfaces being a heated surface.
providing a woven fabric of interwoven cross machine direction and machine direction yarns; and molding a paper contacting surface of said fabric by passing said fabric between two surfaces adapted to apply contact pressure to said fabric, at least one of said two surfaces being a heated surface.
2. The process according to claim 1, wherein at least one of said two surfaces comprises a surface of a roll.
3. The process according to claim 2, wherein said roll is a swimming roll.
4. The process according to claim 1, wherein said two surfaces comprise surfaces of two cooperating rolls configured in a nip press, and said paper making surface is molded by passing said fabric through said nip press.
5. The process according to claim 1 wherein said paper contacting surface comprises long machine direction floats which cross over at least two of said cross machine direction yarns successively before descending between others of said cross machine direction yarns.
6. The process according to claim 1, wherein said at least one of said two surfaces is heated to a temperature between about 130 °C and 240 °C.
7. The process according to claim 1, wherein said fabric is passed between said two surfaces at a speed between about 0.3 m/min and 10 m/min.
8. The process according to claim 1, wherein said fabric is passed between said two surfaces at a specific loading between about 20 kp/cm and 150 kp/cm.
9. The process according to claim 1, wherein said two surfaces comprise surfaces of two cooperating rolls configured in a nip press, said rolls being heated to about 150 °C, and wherein said fabric is passed through said nip press at a speed of about 0.7 m/min.
10. A process for manufacturing a papermakers forming fabric or dryer fabric comprising the steps of:
(1) providing a woven fabric of interwoven cross machine direction and machine direction yarns; and (2) molding a paper contacting surface of said fabric by passing said fabric between two surfaces adapted to apply contact pressure to said fabric, at least one of said two surfaces being a heated surface;
(3) cooling said fabric;
(4) checking said fabric for compliance with desired specifications; and (5) iteratively performing steps (2) through (4) until said fabric complies with said desired specifications.
(1) providing a woven fabric of interwoven cross machine direction and machine direction yarns; and (2) molding a paper contacting surface of said fabric by passing said fabric between two surfaces adapted to apply contact pressure to said fabric, at least one of said two surfaces being a heated surface;
(3) cooling said fabric;
(4) checking said fabric for compliance with desired specifications; and (5) iteratively performing steps (2) through (4) until said fabric complies with said desired specifications.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US49591995A | 1995-06-28 | 1995-06-28 | |
| US08/495,919 | 1995-06-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2153846A1 true CA2153846A1 (en) | 1996-12-29 |
Family
ID=23970511
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2153846 Abandoned CA2153846A1 (en) | 1995-06-28 | 1995-07-13 | Process for producing a papermakers' fabric with a smooth surface |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU6481096A (en) |
| CA (1) | CA2153846A1 (en) |
| WO (1) | WO1997001431A1 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7514030B2 (en) * | 2002-12-30 | 2009-04-07 | Albany International Corp. | Fabric characteristics by flat calendering |
| DE202004009300U1 (en) | 2004-05-19 | 2004-08-19 | Wangner Gmbh & Co. Kg | Dewatering belt for papermaking assembly has a gross-woven polymer gauze whose high points are flattened at high temperature and pressure |
| CA2566520C (en) * | 2004-05-19 | 2012-08-14 | Wangner Gmbh & Co. Kg | Forming sieve for the wet end section of a paper machine |
| DE102007031610A1 (en) | 2007-07-06 | 2009-01-08 | Voith Patent Gmbh | Industrial material e.g. filter band, producing method, involves smoothing planar base structure e.g. fabric, under effect of pressure and heat, and partially forming planar base structure from deformable threads |
| EP2182110A1 (en) | 2008-11-03 | 2010-05-05 | Voith Patent GmbH | Method for generating a paper machine tensioner |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4137984C1 (en) * | 1991-11-19 | 1992-12-17 | Thomas Josef Heimbach Gmbh & Co, 5160 Dueren, De |
-
1995
- 1995-07-13 CA CA 2153846 patent/CA2153846A1/en not_active Abandoned
-
1996
- 1996-06-27 AU AU64810/96A patent/AU6481096A/en not_active Abandoned
- 1996-06-27 WO PCT/US1996/011086 patent/WO1997001431A1/en not_active Ceased
Also Published As
| Publication number | Publication date |
|---|---|
| AU6481096A (en) | 1997-01-30 |
| WO1997001431A1 (en) | 1997-01-16 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Dead |