CA1083869A - Web transfer system - Google Patents
Web transfer systemInfo
- Publication number
- CA1083869A CA1083869A CA305,085A CA305085A CA1083869A CA 1083869 A CA1083869 A CA 1083869A CA 305085 A CA305085 A CA 305085A CA 1083869 A CA1083869 A CA 1083869A
- Authority
- CA
- Canada
- Prior art keywords
- web
- roll
- band
- enclosure
- separation
- 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
Links
- 238000000926 separation method Methods 0.000 claims description 33
- 239000004744 fabric Substances 0.000 claims description 20
- 230000000694 effects Effects 0.000 claims description 4
- 238000007789 sealing Methods 0.000 claims description 3
- 238000011144 upstream manufacturing Methods 0.000 claims description 3
- 238000004140 cleaning Methods 0.000 claims 1
- 238000006073 displacement reaction Methods 0.000 claims 1
- 230000015572 biosynthetic process Effects 0.000 description 2
- 238000007664 blowing Methods 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F2/00—Transferring continuous webs from wet ends to press sections
Landscapes
- Paper (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Paper machines, particularly machines for making light grades of paper, such as tissue, are provided with an extended web transfer zone wherein the area of pressure differential acting upon the web in order to provide transfer of the web is significantly greater than heretofor, thereby permitting satisfactory transfer of the web at lower differentials of pressure, so as to minimized web damage due to entrapment of the fibres thereof by the wire surface.
Paper machines, particularly machines for making light grades of paper, such as tissue, are provided with an extended web transfer zone wherein the area of pressure differential acting upon the web in order to provide transfer of the web is significantly greater than heretofor, thereby permitting satisfactory transfer of the web at lower differentials of pressure, so as to minimized web damage due to entrapment of the fibres thereof by the wire surface.
Description
~` 1083869 This invention is directed to paper making machines and in particular to the provision of web transfer apparatus.
With the advent of modern high speed paper machines, particularly in the case of twin wire machines, the forces acting upon the stock in the formation zone are such that the tendency is accentuated for the formed web to become entrained with one or other of the forming fabrics so that transfer from that fabric for passage out of the machine is impeded. The higher machine speeds generally used further reduce the time available in which to effect web transfer, all of which factors tend to produce increased occurrences of tearing and holing of the product.
In some prior arrangements resort has been made to the use of air jets for the purpose of freeing the paper from the support surface by the action of air blowing through the fabric against the undersurface of the web, over a very restricted portion of the run.
In accordance with the present invention a separation box is provided having an extended enclosed zone traversed by a web and a wire or other web supporting fabric, having air pressure differential creating means connected thereto, to provide a predetermined limited air ~¦ pressure differential thereto relative to atmospheric pressure, to generate a predetermined pressure difference across the width of the web and extending for a significant portion of the run of the fabric, to separate the web from the fabric at a controlled rate of separation.
In the emobidments illustrated herein the extended zone separation box is bounded by fabric guidance rolls, ~, two such embodiments having the web take-off point located downstream therefrom.
,;, ~
. .
. :: . , . - - - : . , :: - . - ~
In another embodiment, the opposing fabric band, located opposite the separation box, in this instance operating under vacuum as a suction box, is guided away from the web by a guide roll positioned intermediately of the two oppositely located guide rolls that bound the separation box.
In a further embodiment the separation box comprises a positive pressure or blow box, being located above a top fabric, with an underlying fabric that is supported in passage downstream of the blow box over a couch or wire roll. The top wire is separated from the web at the downstream edge of the separation box, being guided from the web by the downstream wire roll that bounds the separation box.
Another embodiment employing a suction box of extended length as the separation box, has a fabric guide `~ roll bounding the upstream end of the box, and is provided with a couch roll at the downstream box boundary with a fabric guidance roll located downstream of the couch roll, to remove the opposing band from the web as it leaves the couch roll.
It will be understood that the subject arrangement can be applied, using positive air pressure in the separation box in which case the separation box is located such that the fabric or felt from which the web is to be `l' removed is positioned between the web and the separation box.
In the more readily applied suction case, the separation box is positioned behind the fabric or felt to which the web is to be transferred.
The use of extended suction zones per se in paper machines is not new. Thus, in Christian Schiel's Canadian Patent No. 1,002,801 issued January 4, 1977 Figures 1,2, 4 and 8 show the use of suction boxes of extended length.
However, these boxes are provided in a dewatering role, being located exclusively in the paper formation zone of the machine.
It will be understood that the term "fabric"
encompasses felts, foundrinier wires and synthetic "clothing"
for paper machines and the like.
The present invention thus provides, in a paper machine having a pair of endless fabric bands, to receive in use a layer of stock in web forming relation therebetween in a web forming zone, web separation means located downstream of the forming zone extending substantially the full width of the web and extending a substantial distance in the path of travel of the bands, having enclosure means to form in co-operation with the passage of at least one band and the web therepast a substantially sealed enclosure, and air pressure differential creating means connected with the i.
I sealed enclosure to apply a predetermined differential pressure thereto relative to atmosphere, to separate the web from a selected one of the bands.
` 20 The ongoing and offgoing ends of the enclosure means generally comprise an inlet roll and an outlet roll respectively, rotatably mounted in sealing combination with the enclosure, and in co-operation with the band or bands , and the web.
The guide roller for displacing the first band of the sandwich arrangement containing the web may be located downstream of the extended box enclosure, or it may be located in opposing relation to the box enclosure, dependant upon the desired band return path.
Certain embodiments of the invention are described, reference being made to the accompanying drawings, wherein;
Figure 1 is a schematic side elevation of a first .. , ~- .. . . . . ..
1(~83869 separation box arrangement wherein the first wire return roller is positioned opposite the box;
Figure 2 is a like view of a second arrangement having the first wire return roller alternatively positioned downstream o~ the box and on the same side of the web as the box, and Figure 3 is a like view having a suction roll at the offgoing roll of the separation box.
Referring first to Figure 1, the web separation arrangement 10 i-~ located at the downstream end of a web forming section (not shown) which may be one of a variety of embodiments.
The top and bottom belts 12, 14 which generally comprise fabric or wire fourdrinier belts contain the formed web W therebetween.
In general the arrangement 10 has an ongoing guide roll 18 and an offgoing guide roll 20, with a lower case 22 extending in sealing relation therebetween, having end deckles 24 to enclose a differential pressure volume bounded at its upper face by the belt 14 and the overlying ; web W and belt 12. The end deckles 24 are laterally adjustable relative to the width of the machine, for purposes of minimizing air losses around the edges of web W during operation of the transfer device.
A pair of doctors 25, 27 pivotally mounted at 29, 31 respectively serve to complete the enclosure, being sealed to the lower case 22 by seals 33, 35.
, An air connection 26 connects in this instance with a vacuum pump or fan, in order to reduce the air pressure acting within the separation box, to exert on the web W a pressure having a value less than atmosphere, so as to create a resultant downward force pressing the web W
downwardly on to the belt 14.
_ 4 _ .
A belt guiding roll 28 located in a loop of the top belt 12 and positioned intermediately of rolls, 18, 20 serves to separate the belt 12 from the web W.
In the Figure 2 embodiment the first belt separation may be effected by roll 20, or in an alternative embodiment the belt guiding roll 38 is located in the loop of the top belt 12 on the same side of the web W as the separation box 40, and positioned downstream of couch roll 50, being shown in phantom.
;~ 10 The geometry of the box construction is varied over that of Fig. 1.
The pressure header 46 connects with a source of air supply, in order to provide a pressure greater than atmospheric acting on Web W. A couch roll 50 having a suction box therein further maintains the web W in contact with the lower belt 14.
In the figure 3 embodinlent the offgoing roll 60 of the transfer device 55 is a couch roll, and the air , pressure connection connects with a vacuum header 66. The belt guiding roll 38 is located downstream of the transfer device 55 and oppositely thereof, relative to the web W.
The suction couch roll 60 has internal partitions 61, 63, 65, to co-operate with the lower case 62, and to provide ' differential vacuum to the respective zones of the couch roll.
It will be understood that alternative combinations , of the integers and functions disclosed herein may be ?
utilized, such as positioning the couch roll of Fig. 2 further upstream, within the span of the box 40.
It is contemplated that alternative belt guide , 30 means may be substituted for the rolls 18, 20, of Fig. 1.
~3 From a comparison with the prior art, as the case such as the case of a couch roll, having an open area ~. . . .. -~ . . , -.. , , . . . . . . , .. , , ,.,., .,. , ~ , , .
~083869 ranging from 18~ to 60% of the roll surface area acting over an open surface area of the wire or other fabric in the range 25~ to 30%, the pressure differential applying area provided by a wire or fabric having 4000 to 5000 holes per square inch extends virtually over the full surface area of the sheet, albeit through small holes.
It is contemplated that quite minor pressure differences from atmospheric, in the order of 2-3 inches of mercury within the separation or transfer boxes will effect satisfactory web separation. The use of such moderate pressure differences diminishes the effects of edge losses and seal losses, while the mechanical wear problems associated with seals are reduced, and reliability significantly increased.
. ~
With the advent of modern high speed paper machines, particularly in the case of twin wire machines, the forces acting upon the stock in the formation zone are such that the tendency is accentuated for the formed web to become entrained with one or other of the forming fabrics so that transfer from that fabric for passage out of the machine is impeded. The higher machine speeds generally used further reduce the time available in which to effect web transfer, all of which factors tend to produce increased occurrences of tearing and holing of the product.
In some prior arrangements resort has been made to the use of air jets for the purpose of freeing the paper from the support surface by the action of air blowing through the fabric against the undersurface of the web, over a very restricted portion of the run.
In accordance with the present invention a separation box is provided having an extended enclosed zone traversed by a web and a wire or other web supporting fabric, having air pressure differential creating means connected thereto, to provide a predetermined limited air ~¦ pressure differential thereto relative to atmospheric pressure, to generate a predetermined pressure difference across the width of the web and extending for a significant portion of the run of the fabric, to separate the web from the fabric at a controlled rate of separation.
In the emobidments illustrated herein the extended zone separation box is bounded by fabric guidance rolls, ~, two such embodiments having the web take-off point located downstream therefrom.
,;, ~
. .
. :: . , . - - - : . , :: - . - ~
In another embodiment, the opposing fabric band, located opposite the separation box, in this instance operating under vacuum as a suction box, is guided away from the web by a guide roll positioned intermediately of the two oppositely located guide rolls that bound the separation box.
In a further embodiment the separation box comprises a positive pressure or blow box, being located above a top fabric, with an underlying fabric that is supported in passage downstream of the blow box over a couch or wire roll. The top wire is separated from the web at the downstream edge of the separation box, being guided from the web by the downstream wire roll that bounds the separation box.
Another embodiment employing a suction box of extended length as the separation box, has a fabric guide `~ roll bounding the upstream end of the box, and is provided with a couch roll at the downstream box boundary with a fabric guidance roll located downstream of the couch roll, to remove the opposing band from the web as it leaves the couch roll.
It will be understood that the subject arrangement can be applied, using positive air pressure in the separation box in which case the separation box is located such that the fabric or felt from which the web is to be `l' removed is positioned between the web and the separation box.
In the more readily applied suction case, the separation box is positioned behind the fabric or felt to which the web is to be transferred.
The use of extended suction zones per se in paper machines is not new. Thus, in Christian Schiel's Canadian Patent No. 1,002,801 issued January 4, 1977 Figures 1,2, 4 and 8 show the use of suction boxes of extended length.
However, these boxes are provided in a dewatering role, being located exclusively in the paper formation zone of the machine.
It will be understood that the term "fabric"
encompasses felts, foundrinier wires and synthetic "clothing"
for paper machines and the like.
The present invention thus provides, in a paper machine having a pair of endless fabric bands, to receive in use a layer of stock in web forming relation therebetween in a web forming zone, web separation means located downstream of the forming zone extending substantially the full width of the web and extending a substantial distance in the path of travel of the bands, having enclosure means to form in co-operation with the passage of at least one band and the web therepast a substantially sealed enclosure, and air pressure differential creating means connected with the i.
I sealed enclosure to apply a predetermined differential pressure thereto relative to atmosphere, to separate the web from a selected one of the bands.
` 20 The ongoing and offgoing ends of the enclosure means generally comprise an inlet roll and an outlet roll respectively, rotatably mounted in sealing combination with the enclosure, and in co-operation with the band or bands , and the web.
The guide roller for displacing the first band of the sandwich arrangement containing the web may be located downstream of the extended box enclosure, or it may be located in opposing relation to the box enclosure, dependant upon the desired band return path.
Certain embodiments of the invention are described, reference being made to the accompanying drawings, wherein;
Figure 1 is a schematic side elevation of a first .. , ~- .. . . . . ..
1(~83869 separation box arrangement wherein the first wire return roller is positioned opposite the box;
Figure 2 is a like view of a second arrangement having the first wire return roller alternatively positioned downstream o~ the box and on the same side of the web as the box, and Figure 3 is a like view having a suction roll at the offgoing roll of the separation box.
Referring first to Figure 1, the web separation arrangement 10 i-~ located at the downstream end of a web forming section (not shown) which may be one of a variety of embodiments.
The top and bottom belts 12, 14 which generally comprise fabric or wire fourdrinier belts contain the formed web W therebetween.
In general the arrangement 10 has an ongoing guide roll 18 and an offgoing guide roll 20, with a lower case 22 extending in sealing relation therebetween, having end deckles 24 to enclose a differential pressure volume bounded at its upper face by the belt 14 and the overlying ; web W and belt 12. The end deckles 24 are laterally adjustable relative to the width of the machine, for purposes of minimizing air losses around the edges of web W during operation of the transfer device.
A pair of doctors 25, 27 pivotally mounted at 29, 31 respectively serve to complete the enclosure, being sealed to the lower case 22 by seals 33, 35.
, An air connection 26 connects in this instance with a vacuum pump or fan, in order to reduce the air pressure acting within the separation box, to exert on the web W a pressure having a value less than atmosphere, so as to create a resultant downward force pressing the web W
downwardly on to the belt 14.
_ 4 _ .
A belt guiding roll 28 located in a loop of the top belt 12 and positioned intermediately of rolls, 18, 20 serves to separate the belt 12 from the web W.
In the Figure 2 embodiment the first belt separation may be effected by roll 20, or in an alternative embodiment the belt guiding roll 38 is located in the loop of the top belt 12 on the same side of the web W as the separation box 40, and positioned downstream of couch roll 50, being shown in phantom.
;~ 10 The geometry of the box construction is varied over that of Fig. 1.
The pressure header 46 connects with a source of air supply, in order to provide a pressure greater than atmospheric acting on Web W. A couch roll 50 having a suction box therein further maintains the web W in contact with the lower belt 14.
In the figure 3 embodinlent the offgoing roll 60 of the transfer device 55 is a couch roll, and the air , pressure connection connects with a vacuum header 66. The belt guiding roll 38 is located downstream of the transfer device 55 and oppositely thereof, relative to the web W.
The suction couch roll 60 has internal partitions 61, 63, 65, to co-operate with the lower case 62, and to provide ' differential vacuum to the respective zones of the couch roll.
It will be understood that alternative combinations , of the integers and functions disclosed herein may be ?
utilized, such as positioning the couch roll of Fig. 2 further upstream, within the span of the box 40.
It is contemplated that alternative belt guide , 30 means may be substituted for the rolls 18, 20, of Fig. 1.
~3 From a comparison with the prior art, as the case such as the case of a couch roll, having an open area ~. . . .. -~ . . , -.. , , . . . . . . , .. , , ,.,., .,. , ~ , , .
~083869 ranging from 18~ to 60% of the roll surface area acting over an open surface area of the wire or other fabric in the range 25~ to 30%, the pressure differential applying area provided by a wire or fabric having 4000 to 5000 holes per square inch extends virtually over the full surface area of the sheet, albeit through small holes.
It is contemplated that quite minor pressure differences from atmospheric, in the order of 2-3 inches of mercury within the separation or transfer boxes will effect satisfactory web separation. The use of such moderate pressure differences diminishes the effects of edge losses and seal losses, while the mechanical wear problems associated with seals are reduced, and reliability significantly increased.
. ~
Claims (9)
1. In a paper machine having a pair of endless fabric bands, to receive in use a layer of stock in web forming relation therebetween in a web forming zone, web separation means located downstream of the forming zone extending substantially the full width of the web, and extending a substantial distance in the path of travel of said bands, having enclosure means to form in co-operation with the passage of a said band and said web therepast a substantially sealed enclosure, and air pressure differential creating means connected with the sealed enclosure to apply a predetermined differential pressure thereto relative to atmosphere, to effect controlled displacement of said web from a said band.
2. The separation means as claimed in claim 1, said enclosure means including an inlet roll and an outlet roll rotatably mounted at the respective upstream and downstream ends thereof in sealing relation therewith, to receive one said band in guiding relation therewith.
3. The separation means as claimed in claim 2 wherein said outlet roll is a couch roll, having a suction box located therein.
4. The separation means as claimed in claim 1, claim 2, or claim 3, including end deckles providing adjustable side closure of said sealed enclosure.
5. The separation means as claimed in claim 1, claim 2 or claim 3 having a band guidance roll located intermediate the ends of said enclosure means and on the side of said bands remote from the enclosure means, having the band adjacent the guidance roll trained thereabout in separating relation from said web.
6. The separation means as claimed in claim 2 including doctor means located in surface cleaning relation with a said roll.
7. The separation means as claimed in claim 1 or claim 2 having a band guidance roll located downstream of said enclosure and on the side of said bands opposite the enclosure, to receive the nearest said band in guided relation thereabout for separation of the band from said web.
8. The separation means as claimed in claim 3 including a band separation roll located on the side of said web opposite to said couch roll, and positioned downstream therefrom.
9. The separation means as claimed in claim 2 or claim 3, said outlet roll having the adjacent said belt trained thereabout in offgoing relation relative to said web.
Priority Applications (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA305,085A CA1083869A (en) | 1978-06-09 | 1978-06-09 | Web transfer system |
| FI791741A FI791741A (en) | 1978-06-09 | 1979-05-31 | TRANSPORTSYSTEM FOER BANOR |
| IT23156/79A IT1121311B (en) | 1978-06-09 | 1979-05-31 | BELT TRANSFER SYSTEM FOR PAPER MACHINES |
| DE19792922623 DE2922623A1 (en) | 1978-06-09 | 1979-06-02 | Paper making machine web separation - using suction box to allow forming bands to be peeled from paper without damage |
| JP6951979A JPS54160806A (en) | 1978-06-09 | 1979-06-05 | Web separating apparatus |
| BR7903642A BR7903642A (en) | 1978-06-09 | 1979-06-08 | SEPARATION DEVICES IN A CONTINUOUS FABRICATION MACHINE SEPARATION DEVICES IN A CONTINUOUS PAPER MANUFACTURING MACHINE |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA305,085A CA1083869A (en) | 1978-06-09 | 1978-06-09 | Web transfer system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1083869A true CA1083869A (en) | 1980-08-19 |
Family
ID=4111655
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA305,085A Expired CA1083869A (en) | 1978-06-09 | 1978-06-09 | Web transfer system |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS54160806A (en) |
| BR (1) | BR7903642A (en) |
| CA (1) | CA1083869A (en) |
| DE (1) | DE2922623A1 (en) |
| FI (1) | FI791741A (en) |
| IT (1) | IT1121311B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5314585A (en) * | 1993-05-10 | 1994-05-24 | Champion International Corporation | Low shear Uhle box |
| DE102020128265A1 (en) | 2020-10-28 | 2022-04-28 | Voith Patent Gmbh | Alternative suction roll concept |
-
1978
- 1978-06-09 CA CA305,085A patent/CA1083869A/en not_active Expired
-
1979
- 1979-05-31 IT IT23156/79A patent/IT1121311B/en active
- 1979-05-31 FI FI791741A patent/FI791741A/en not_active Application Discontinuation
- 1979-06-02 DE DE19792922623 patent/DE2922623A1/en not_active Withdrawn
- 1979-06-05 JP JP6951979A patent/JPS54160806A/en active Pending
- 1979-06-08 BR BR7903642A patent/BR7903642A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| FI791741A (en) | 1979-12-10 |
| IT7923156A0 (en) | 1979-05-31 |
| BR7903642A (en) | 1980-02-05 |
| JPS54160806A (en) | 1979-12-19 |
| DE2922623A1 (en) | 1979-12-20 |
| IT1121311B (en) | 1986-04-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |