CA1335420C - Belt as a replacement for a conventional press roll cover - Google Patents
Belt as a replacement for a conventional press roll coverInfo
- Publication number
- CA1335420C CA1335420C CA000573191A CA573191A CA1335420C CA 1335420 C CA1335420 C CA 1335420C CA 000573191 A CA000573191 A CA 000573191A CA 573191 A CA573191 A CA 573191A CA 1335420 C CA1335420 C CA 1335420C
- Authority
- CA
- Canada
- Prior art keywords
- press
- belt
- papermachine
- elastic
- compressible
- 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
- D21F3/00—Press section of machines for making continuous webs of paper
- D21F3/02—Wet presses
- D21F3/0209—Wet presses with extended press nip
- D21F3/0218—Shoe presses
- D21F3/0227—Belts or sleeves therefor
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F3/00—Press section of machines for making continuous webs of paper
- D21F3/02—Wet presses
Landscapes
- Paper (AREA)
Abstract
This invention consists of an elastic, compressible belt, whose total length is greater than the circumference of a press roll, for use as a replacement for a conventional press roll cover in a papermaking machine. It is envisioned that such a belt would be supported by the press roll, but would run independently from it, and supply required elastic media to the nip of the press. The belt can have a smooth, grooved, or perforated surface, as required by the given application.
Description
~ I ~
A BELT AS A REPLACEMENT FOR A
CONVENTIONAL PRESS ROLL COVER
BACKGROUND OF THE INVENTION
Field of the Invention This invention relates to the removal of water from the papersheet, wet felt combination in the nip of the press rolls in a papermaking machine. More specifically, it presents an elastic, compressible belt, whose total length is greater than the circumference of a press roll, for use as a replacement for a conventional press roll cover.
I
Description of the Related Art An important step in the production of paper occurs in the press section of the papermaking machine. There, a sheet of fibrous material, either carried on top of a belt of water-absorbing felt or held between two such belts, passes through a series of openings between rolls. In each passage through such an opening, referred to as the nip of the rolls, water is squeezed from the fibrous material and absorbed by the felt. The aim of this procedure is to remove as much water as possible from the sheet before it emerges from the press section of the machine and enters the dryer section.
In this way, less water will remain to be removed by heat in the dryer section, and costs related to heat production will be reduced.
In the dewatering presses, however, it is desirable to apply pressure to the paper sheet, wet felt combination over various time elements, depending on the type of paper being manufactured. This so-called dwell time is related not only to the speed of the sheet-felt combination, but also to the compressibility of the roll surfaces. For short time elements requiring high specific pressure, the press rolls are equipped with very inelastic surfaces. Where it is - /
1 33~420 desirable to extend this time element and to reduce the spe-cific pressure, the press rolls are equipped with covers that are compressible and elastic. The exact compressibility char-acteristics of the press roll cover used depend on the par-ticular conditions desired in the nip of the press.
Eventually, due to cyclical compressive fatigue, press roll covers will fail in operation. It will then become necessary to remove the press roll from the paper ~ch;ne for either regrinding or recovering. Such a procedure can remove the paper ~ch;ne from operation for a considerable length of time.
This invention provides an alternate method of sup-plying an elastic, compressible media in the nip of the press instead of using the conventional press-roll cover. It is now possible to produce a belt which has an elastic, compressible surface similar to that of a conventional, press-roll cover.
Using the method envisioned here, such a belt, wrapped around the shell of the press roll, would replace the press-roll cover. In this way, the papermaker can be provided with the elastic media needed in the press nip without actually cover-ing the press roll.
SUMMARY OF THE INVENTION
The construction in accordance with the present in-vention pertains to the press section of a papermachine wherein water is removed from a wet sheet of fibrous material during the manufacture of paper and the like, the press sec-tion including at least one press roll extending across the width of the papermachine. The press roll is cylindrical and has a circumference, and has a press nip through which a com-bination of the wet sheet of fibrous material and at least onewet-press felt fabric pass to dewater the wet sheet of fibrous ., -- -- -- - --::- ..
material. The improvement comprises an elastic, compressible belt, the belt providing an elastic, compressible medium in endless form having a total length greater than the circum-ference of the press roll and a width substantially equal to that of the papermachine. The belt is supported by the press roll and travels in the endless form about the press roll under tension controlled by a movable stretch roll. The belt further is directed about the press roll by a plurality of guide rolls, so that the wet sheet of fibrous material may be dewatered in the press nip against the elastic, compressible medium in the form of the elastic, compressible belt. The belt is used to replace a conventional press roll cover.
Accordingly, this invention, which includes an elas-tic, compressible belt, whose total length is greater than the circumference of a press roll, is to be used as a replacement for the conventional press roll cover now used in the paper-making industry. Supported by the shell of the press roll, the belt would run independently through the nip in conjunction with the sheet of fibrous material and wet felt combination.
Guide and stretch rolls would be required to direct and - 2a -._ control the motion of the belt around the press roll and to maintain its tension at a suitable level. The outer surface of such a belt can be smooth, grooved, or have holes so that it can replace roll covers having those surface characteristics.
The user will benefit from the numerous, novel advantages to be obtained through the application of this invention. When compressive fatigue failure eventually occurs in the elastic media of t~e belt, it would not be necessary to remove the press roll completely from the paper machine for recovering. Instead, one would simply shut down the papermaking machine for the comparatively short span of time required to remove the used belt from the machine and install a new one in its place.
Assuming that compressive fatigue failure occurs after some large number of compressive cycles, through the use of a belt of the kind shown by this invention, a longer machine running time will elapse before a given portion of the length of the belt will have experienced the same number of compressive cycles of passage through the nip as a given portion of the press roll cover. This is because the belt will be longer than the circumference of the press roll. The belt will then by comparison have a much longer running life than the press roll cover.
Since it will be easier to change a cover belt than change a press roll cover, and since a cover belt represents a smaller capital investment, in applying this invention the papermaker will have an increased flexibility to change his nip conditions as called for by the given application, and will be required to carry fewer press rolls in his maint~n~nce inventory. Machine "down" time during changes will be shorter than would be the case if an entire roll or roll cover were being replaced.
Because of the ease of changing belts, the papermaker will also be able to change from a smooth belt to a grooved or perforated belt at his discretion.
BRIEF DESCRIPTION OF THE DRAWING
In Figure 1 is shown a set of press rolls in a papermaking machine to which this invention has been applied.
; Figures 2a-2d show portions of the surfaces of belts of this invention having different surface characteristics.
Figures 3a-3d show side sectional views of the belts depicted in Figures 2a-2d respectively.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The main purpose of this invention is to provide the papermaker with an elastic, compressible belt for use in the press section of the papermaking machine. It is intended that such a belt form the basis of an alternate method of supplying an elastic media to the press nip and make it unnecesc~ry in the future to actually cover the press rolls with an elastic, compressible material. A mode in which this invention can be put into use is illustrated in Figure 1.
The wet sheet of fibrous material 1, from which water is being removed, is held between the top 2 and bottom 3 water-absorbing felts as it passes between the upper 4 and lower 5 press rolls. The actual removal of water from the sheet 1 ; occurs in the press nip 6, the region between the upper 4 and lower 5 press rolls, where the combination of wet sheet 1 and water-absorbing felts 2,3 is squeezed together. An elastic, compressible belt 7 having a total length greater than the circumference of the lower press roll 5 and approximately the same width as that roll 5 in the cross-machine direction, is supported by the lower press roll 5 and moves through the nip 6 with and below the combination of sheet 1 and water absorbing felts 2, 3. Guide rolls 8 maintain a requisite level of tension on the belt 7 and control and direct its motion through the nip 6. A movable stretch roll 9 is used to adjust the level of tension desired in the belt 7. The mobility of the stretch roll 9 is indicated by the vertical arrows above and below the circle representing it. All other arrows indicate the motions of components of this system during its regular operation.
Figures 2a-2d show four variants for that surface of the belt 7 which makes contact with the press felt 3. Figure 2a represents a smooth belt 7; Figure 2b shows a belt 7 whose surface has grooves 10. Figure 2c shows a perforated belt 7 with holes 11 passing completely through its structure.
Figure 2d shows a belt 7 whose surface has depressions 12 not passing completely through its structure.
Figures 3a-3d show side sectional views of the belts 7 in Figures 2a-2d respectively to present the grooves 10, holes 11, and depressions 12 in greater detail.
Modifications would be obvious to one skilled in the art without departing from the scope of the invention as defined in the appended claims.
A BELT AS A REPLACEMENT FOR A
CONVENTIONAL PRESS ROLL COVER
BACKGROUND OF THE INVENTION
Field of the Invention This invention relates to the removal of water from the papersheet, wet felt combination in the nip of the press rolls in a papermaking machine. More specifically, it presents an elastic, compressible belt, whose total length is greater than the circumference of a press roll, for use as a replacement for a conventional press roll cover.
I
Description of the Related Art An important step in the production of paper occurs in the press section of the papermaking machine. There, a sheet of fibrous material, either carried on top of a belt of water-absorbing felt or held between two such belts, passes through a series of openings between rolls. In each passage through such an opening, referred to as the nip of the rolls, water is squeezed from the fibrous material and absorbed by the felt. The aim of this procedure is to remove as much water as possible from the sheet before it emerges from the press section of the machine and enters the dryer section.
In this way, less water will remain to be removed by heat in the dryer section, and costs related to heat production will be reduced.
In the dewatering presses, however, it is desirable to apply pressure to the paper sheet, wet felt combination over various time elements, depending on the type of paper being manufactured. This so-called dwell time is related not only to the speed of the sheet-felt combination, but also to the compressibility of the roll surfaces. For short time elements requiring high specific pressure, the press rolls are equipped with very inelastic surfaces. Where it is - /
1 33~420 desirable to extend this time element and to reduce the spe-cific pressure, the press rolls are equipped with covers that are compressible and elastic. The exact compressibility char-acteristics of the press roll cover used depend on the par-ticular conditions desired in the nip of the press.
Eventually, due to cyclical compressive fatigue, press roll covers will fail in operation. It will then become necessary to remove the press roll from the paper ~ch;ne for either regrinding or recovering. Such a procedure can remove the paper ~ch;ne from operation for a considerable length of time.
This invention provides an alternate method of sup-plying an elastic, compressible media in the nip of the press instead of using the conventional press-roll cover. It is now possible to produce a belt which has an elastic, compressible surface similar to that of a conventional, press-roll cover.
Using the method envisioned here, such a belt, wrapped around the shell of the press roll, would replace the press-roll cover. In this way, the papermaker can be provided with the elastic media needed in the press nip without actually cover-ing the press roll.
SUMMARY OF THE INVENTION
The construction in accordance with the present in-vention pertains to the press section of a papermachine wherein water is removed from a wet sheet of fibrous material during the manufacture of paper and the like, the press sec-tion including at least one press roll extending across the width of the papermachine. The press roll is cylindrical and has a circumference, and has a press nip through which a com-bination of the wet sheet of fibrous material and at least onewet-press felt fabric pass to dewater the wet sheet of fibrous ., -- -- -- - --::- ..
material. The improvement comprises an elastic, compressible belt, the belt providing an elastic, compressible medium in endless form having a total length greater than the circum-ference of the press roll and a width substantially equal to that of the papermachine. The belt is supported by the press roll and travels in the endless form about the press roll under tension controlled by a movable stretch roll. The belt further is directed about the press roll by a plurality of guide rolls, so that the wet sheet of fibrous material may be dewatered in the press nip against the elastic, compressible medium in the form of the elastic, compressible belt. The belt is used to replace a conventional press roll cover.
Accordingly, this invention, which includes an elas-tic, compressible belt, whose total length is greater than the circumference of a press roll, is to be used as a replacement for the conventional press roll cover now used in the paper-making industry. Supported by the shell of the press roll, the belt would run independently through the nip in conjunction with the sheet of fibrous material and wet felt combination.
Guide and stretch rolls would be required to direct and - 2a -._ control the motion of the belt around the press roll and to maintain its tension at a suitable level. The outer surface of such a belt can be smooth, grooved, or have holes so that it can replace roll covers having those surface characteristics.
The user will benefit from the numerous, novel advantages to be obtained through the application of this invention. When compressive fatigue failure eventually occurs in the elastic media of t~e belt, it would not be necessary to remove the press roll completely from the paper machine for recovering. Instead, one would simply shut down the papermaking machine for the comparatively short span of time required to remove the used belt from the machine and install a new one in its place.
Assuming that compressive fatigue failure occurs after some large number of compressive cycles, through the use of a belt of the kind shown by this invention, a longer machine running time will elapse before a given portion of the length of the belt will have experienced the same number of compressive cycles of passage through the nip as a given portion of the press roll cover. This is because the belt will be longer than the circumference of the press roll. The belt will then by comparison have a much longer running life than the press roll cover.
Since it will be easier to change a cover belt than change a press roll cover, and since a cover belt represents a smaller capital investment, in applying this invention the papermaker will have an increased flexibility to change his nip conditions as called for by the given application, and will be required to carry fewer press rolls in his maint~n~nce inventory. Machine "down" time during changes will be shorter than would be the case if an entire roll or roll cover were being replaced.
Because of the ease of changing belts, the papermaker will also be able to change from a smooth belt to a grooved or perforated belt at his discretion.
BRIEF DESCRIPTION OF THE DRAWING
In Figure 1 is shown a set of press rolls in a papermaking machine to which this invention has been applied.
; Figures 2a-2d show portions of the surfaces of belts of this invention having different surface characteristics.
Figures 3a-3d show side sectional views of the belts depicted in Figures 2a-2d respectively.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The main purpose of this invention is to provide the papermaker with an elastic, compressible belt for use in the press section of the papermaking machine. It is intended that such a belt form the basis of an alternate method of supplying an elastic media to the press nip and make it unnecesc~ry in the future to actually cover the press rolls with an elastic, compressible material. A mode in which this invention can be put into use is illustrated in Figure 1.
The wet sheet of fibrous material 1, from which water is being removed, is held between the top 2 and bottom 3 water-absorbing felts as it passes between the upper 4 and lower 5 press rolls. The actual removal of water from the sheet 1 ; occurs in the press nip 6, the region between the upper 4 and lower 5 press rolls, where the combination of wet sheet 1 and water-absorbing felts 2,3 is squeezed together. An elastic, compressible belt 7 having a total length greater than the circumference of the lower press roll 5 and approximately the same width as that roll 5 in the cross-machine direction, is supported by the lower press roll 5 and moves through the nip 6 with and below the combination of sheet 1 and water absorbing felts 2, 3. Guide rolls 8 maintain a requisite level of tension on the belt 7 and control and direct its motion through the nip 6. A movable stretch roll 9 is used to adjust the level of tension desired in the belt 7. The mobility of the stretch roll 9 is indicated by the vertical arrows above and below the circle representing it. All other arrows indicate the motions of components of this system during its regular operation.
Figures 2a-2d show four variants for that surface of the belt 7 which makes contact with the press felt 3. Figure 2a represents a smooth belt 7; Figure 2b shows a belt 7 whose surface has grooves 10. Figure 2c shows a perforated belt 7 with holes 11 passing completely through its structure.
Figure 2d shows a belt 7 whose surface has depressions 12 not passing completely through its structure.
Figures 3a-3d show side sectional views of the belts 7 in Figures 2a-2d respectively to present the grooves 10, holes 11, and depressions 12 in greater detail.
Modifications would be obvious to one skilled in the art without departing from the scope of the invention as defined in the appended claims.
Claims (5)
1. In a press section of a papermachine, wherein water is removed from a wet sheet of fibrous material during the manufacture of paper and the like, said press section includ-ing at least one press roll extending across the width of said papermachine, said press roll being cylindrical and having a circumference, and having a press nip through which a combina-tion of said wet sheet of fibrous material and at least one wet-press felt fabric pass to dewater said wet sheet of fi-brous material, the improvement comprising: an elastic, com-pressible belt, said belt providing an elastic, compressible medium in endless form having a total length greater than the circumference of said press roll and a width substantially equal to that of said papermachine, said belt being wrapped around said press roll and traveling in said endless form about said press roll under tension controlled by a movable stretch roll, said belt further being directed about said press roll by a plurality of guide rolls, so that said wet sheet of fibrous material may be dewatered in said press nip against said elastic, compressible medium in the form of said elastic, compressible belt, said belt being used to replace a conventional press roll cover.
2. In a press section of a papermachine, the improve-ment as claimed in claim 1 wherein said elastic, compressible belt has a smooth surface for contacting said combination of said wet sheet of fibrous material and said wet-press felt fabric in said press nip of said papermachine.
3. In a press section of a papermachine, the improve-ment as claimed in claim 1 wherein said elastic, compressible belt has a surface with regularly spaced, parallel grooves for contacting said combination of said wet sheet of fibrous mate-rial and said wet-press felt fabric in said press nip of said papermachine.
4. In a press section of a papermachine, the improve-ment as claimed in claim 1, wherein said elastic, compressible belt has perforations passing completely therethrough.
5. In a press section of a papermachine, the improve-ment as claimed in claim 1 wherein said elastic, compressible belt has a surface with a plurality of depressions, said depressions not passing completely through said belt, for con-tacting said combination of said wet sheet of fibrous material and said wet-press felt fabric in said press nip of said papermachine.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US17522988A | 1988-03-30 | 1988-03-30 | |
| US175,229 | 1988-03-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1335420C true CA1335420C (en) | 1995-05-02 |
Family
ID=22639471
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000573191A Expired - Fee Related CA1335420C (en) | 1988-03-30 | 1988-07-27 | Belt as a replacement for a conventional press roll cover |
Country Status (11)
| Country | Link |
|---|---|
| AT (1) | AT393390B (en) |
| BR (1) | BR8802839A (en) |
| CA (1) | CA1335420C (en) |
| DE (1) | DE3832411A1 (en) |
| FI (1) | FI882191A (en) |
| IT (1) | IT8848047A0 (en) |
| NL (1) | NL8801273A (en) |
| NO (1) | NO882324D0 (en) |
| NZ (1) | NZ224687A (en) |
| SE (1) | SE8801969D0 (en) |
| ZA (1) | ZA885017B (en) |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB770702A (en) * | 1954-12-31 | 1957-03-20 | Dominion Eng Works Ltd | Two-roll press for paper machines |
| GB1025000A (en) * | 1963-10-15 | 1966-04-06 | Huyck Corp | Improvements in or relating to the manufacture of paper |
| FR2030527A5 (en) * | 1969-06-20 | 1970-11-13 | Centre Tech Ind Papier | |
| FI822425L (en) * | 1982-07-07 | 1984-01-08 | Valmet Oy | PROCEDURE FOR THE PRESS RELEASE OF THE PRESS RELEASE OF THE FIBER, THE SYNNER AND THE PAPER-ELLER |
-
1988
- 1988-05-10 FI FI882191A patent/FI882191A/en not_active Application Discontinuation
- 1988-05-18 NZ NZ224687A patent/NZ224687A/en unknown
- 1988-05-18 NL NL8801273A patent/NL8801273A/en not_active Application Discontinuation
- 1988-05-26 NO NO882324A patent/NO882324D0/en unknown
- 1988-05-26 SE SE8801969A patent/SE8801969D0/en unknown
- 1988-06-02 IT IT8848047A patent/IT8848047A0/en unknown
- 1988-06-10 BR BR8802839A patent/BR8802839A/en not_active IP Right Cessation
- 1988-07-12 ZA ZA885017A patent/ZA885017B/en unknown
- 1988-07-27 CA CA000573191A patent/CA1335420C/en not_active Expired - Fee Related
- 1988-09-05 AT AT2180/88A patent/AT393390B/en not_active IP Right Cessation
- 1988-09-23 DE DE3832411A patent/DE3832411A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| AT393390B (en) | 1991-10-10 |
| DE3832411A1 (en) | 1989-10-12 |
| SE8801969D0 (en) | 1988-05-26 |
| NZ224687A (en) | 1992-06-25 |
| ATA218088A (en) | 1991-03-15 |
| ZA885017B (en) | 1990-02-28 |
| FI882191A (en) | 1989-10-01 |
| NO882324D0 (en) | 1988-05-26 |
| NL8801273A (en) | 1989-10-16 |
| FI882191A0 (en) | 1988-05-10 |
| IT8848047A0 (en) | 1988-06-02 |
| BR8802839A (en) | 1990-01-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |