CA1097117A - Procedure and means in a paper machine for the detachment of the web from the forming wire and for its transfer in closed conduction to the press section of the paper machine - Google Patents
Procedure and means in a paper machine for the detachment of the web from the forming wire and for its transfer in closed conduction to the press section of the paper machineInfo
- Publication number
- CA1097117A CA1097117A CA312,965A CA312965A CA1097117A CA 1097117 A CA1097117 A CA 1097117A CA 312965 A CA312965 A CA 312965A CA 1097117 A CA1097117 A CA 1097117A
- Authority
- CA
- Canada
- Prior art keywords
- web
- roll
- press
- felt
- transfer
- 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
- 238000012546 transfer Methods 0.000 title claims abstract description 150
- 238000000034 method Methods 0.000 title claims description 16
- 238000004519 manufacturing process Methods 0.000 claims abstract description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 11
- 238000003825 pressing Methods 0.000 claims description 7
- 230000009471 action Effects 0.000 claims description 4
- 239000007787 solid Substances 0.000 claims description 3
- 238000004891 communication Methods 0.000 claims 2
- 230000001154 acute effect Effects 0.000 claims 1
- 238000005507 spraying Methods 0.000 claims 1
- 230000008859 change Effects 0.000 abstract description 11
- 230000032258 transport Effects 0.000 abstract description 6
- 238000007664 blowing Methods 0.000 description 11
- 230000000694 effects Effects 0.000 description 9
- 230000008901 benefit Effects 0.000 description 4
- 238000010276 construction Methods 0.000 description 4
- 238000007789 sealing Methods 0.000 description 4
- 230000003750 conditioning effect Effects 0.000 description 3
- 239000011888 foil Substances 0.000 description 3
- 241000237074 Centris Species 0.000 description 2
- 210000000481 breast Anatomy 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 230000001737 promoting effect Effects 0.000 description 2
- 206010013457 Dissociation Diseases 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000005406 washing Methods 0.000 description 1
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F9/00—Complete machines for making continuous webs of paper
- D21F9/003—Complete machines for making continuous webs of paper of the twin-wire type
-
- 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
- D21F3/04—Arrangements thereof
Landscapes
- Paper (AREA)
Abstract
PAPER MANUFACTURING STRUCTURE PARTICULARLY
FOR DETACHING A WEB FROM A WIRE
ABSTRACT OF THE DISCLOSURE
A paper machine has a forming wire loop which trans-ports a web to a detachment transfer roll situated inside said wire loop at a detaching location where the web is to be de-tached from the wire and transported to a press section.
A relatively dry felt engages the web on a sector of the de-tachment transfer roll at the detaching location and receives the web from the wire and continues to transport the web, while it adheres to the felt, to the press section. The detachment of the web from the wire on the detachment transfer roll is facilitated by the centrifugal force acting on the web which results from the substantial change of direction undergone by the web on the detachment transfer roll. In one embodiment, the press felt is directed to cover the web on a sector of the detachment roll by a press suction roll located on sub-stantially the same level as the detachment transfer roll, the press roll having a suction sector which facilitates trans-fer of the web from the wire to the felt.
FOR DETACHING A WEB FROM A WIRE
ABSTRACT OF THE DISCLOSURE
A paper machine has a forming wire loop which trans-ports a web to a detachment transfer roll situated inside said wire loop at a detaching location where the web is to be de-tached from the wire and transported to a press section.
A relatively dry felt engages the web on a sector of the de-tachment transfer roll at the detaching location and receives the web from the wire and continues to transport the web, while it adheres to the felt, to the press section. The detachment of the web from the wire on the detachment transfer roll is facilitated by the centrifugal force acting on the web which results from the substantial change of direction undergone by the web on the detachment transfer roll. In one embodiment, the press felt is directed to cover the web on a sector of the detachment roll by a press suction roll located on sub-stantially the same level as the detachment transfer roll, the press roll having a suction sector which facilitates trans-fer of the web from the wire to the felt.
Description
~97~7 The present invention relates to paper-manufacturing methods and machines.
In particular, the present invention relates to methods and machines of this type which are concerned with the detaching of the paper web ~rom the forming wire which may, for example, be a wire of a twin-wire former, with this wire t~ansporting the web beyond the wire section to the press section.
The invention relates in particular to a method and apparatus of the above type which are designed to transport the web without any open draw from the wire to the press seetion of the paper machine, so that the web is continuously supported as it travels from the wire to the press section.
A detachment transfer roll inside the foxmin wire loop is utilized for contributing toward detaching of the web from the wire and adhering the web to a felt which transports the web from the wire to the press section.
As is well known, the operations in connection with which a web, which has been formed on the wire of a paper machine, is detached from the wire and transferred to the press section is extremely important, having a great influence on the re~iability of the operation of the paper machine. In paper machines which operate at relatively low speeds, it is possible to utilize open draws resulting from a speed differential between the wire and press sections.
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However, with paper machines which operate at ~ h speeds or which are utilized in the manufacture of relatively thin and therefore low-strength paper, it is known that closed transfer systems, without any open draw, must be utilized, so that the web is continuously supported while it travels from the wire to the press section.
Systems of this latter type usually operate in such a manner that a transfer felt of the press section is guided into contact with the web on the wire. Such a transfer felt may be pres~ed by way of a rotating roll against the web on the wire so that the web adheres to the felt to become de-tached from the wire and to continue to be transported by the felt which then transports the web to the first press nip of the press section.
In general there are two main types of closed transfer systems. The simplest is the so-called lick-up transfer based on the capability of a wet "lic~-up" felt to adhere the paper web to its surface. The other type of closed transfer system is a vacuum pick-up system which developed from the first system. By providing at the transfer point a vacuum, it is possible to reliably bring about trans-fer of the web from the wire to the felt with the web adheriDg reliably to the felt. A vacuum type of pick-up system offers greater possibilities than the first system, particularly for example, with regard to the selection of the quality of the felt. Particularly in those cases where the transfer felt also operates as a press felt, several requirements are imposed on the transfer felt. These requirements include a requirement ~09~
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that the web must adhere reliably to the surface of tlle felt at the attaching location while on the other hand the felt ~nust function eficientl~ at tlle dewatering first press nip of the press section.
In order for the web to reliably adhere to the felt between the detaching location and the first press nip, it has heen conventional practice to use a relatively wet felt. How-ever, where the transfer felt has also been employed as the press felt, the wetness of the felt to promote web adhesion of course lessens the ability for dewatering the web at the first press nip.
Thus, from the viewpoint o maximum efficiency in dewatering, it is desirable to maintain the felt as dry as possible.
Vacuum picX-up systems utilizing separate pick-up suction roll have gained a wide use. However, such conventional systems are encumbered by a number of d~awbacks.
Thus, conventional suction rolls of the above type are expensive, requiring an individual driving motor and control system, and they are exceedingly noisy in operation.
Furthermore, such suction rolls consume a great deal of air, due not only to the fact that the air which passes through the web and felt also enters into the suction system but also due to the fact that the air arriving in the suction zone in the holes of the suction roll shell must be moved out of these holes once during each revolution of the shell.
The amount of such "hole air" may in large, fast running machines be twice or even three times the air quantity traversing the web. In addition, numerous difficulties result from ~;~971 7 ., 3 " : .
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the fact that proper seals must be maintained by sealing water at the suction box which forms part of the suction roll.
The detaching of the web from the wire in a con-ventional Fourdrinier machine utilizing a separate pick-up suction roll takes place at a location situated on the wire run between the couch roll and the traction roll. At this location the wire travels downwardly at an angle of approximately 45 with respect to a horizontal plane. This detaching location is determined by the usual construction of the wire section and press section and by their location with respect to each other.
Subsequent to the detachin~ location the picX-up felt and the web adhering thereto la~ the pick-up roll through an angle of about 45-90 , and then the felt and the web adhering thereto travel to the press section. This latter change in the direction of travel of the felt at the detaching location, caused by the above lapping of the pick-up roll by the felt, causes under some circumstances, such as high speed or an unsuitable felt, a tendency for the web to detach itself from the pick-up felt as a result of the action of centrifugal force~ In ~rder to counteract this latter tendency for detachment of the web from the felt while travelling on the pick-up roll,it is essential to provide the pick-up roll with a suction zone extending through a substantial distance beyond the detach-ing zone itself. ~n this way it is possi~le to insure that the we~ will remain adhering t~ the felt, but of course this reliability in the operation is obtained at the cost o~ a ~97~
considerable additional load on the suction system of the pick-up roll. As a result, the suction roll requires a capacity in addition to that which would be required if the t:asX of the suction roll were only to effect detachment of the web from the wire and adhering the web to the ~elt.
SUMMARY OF THF INVENTION
It is accordingly a primary object of the present invention to provide a method and a~paratus ca~able of accornplishing an effective transfer of the web from the wire to a transfer felt while utilizing kinetic energy of the rota1:ing structural elements of the wire section as well as o the web itself, while also making effective use o centrifugal force in various ways to contribute to detaching o the web from the wire and adhering thereof to the transfer felt while at the same time minimizing the number of re~uired suction rolls, the e~penditure particularly of suction energy, and the noise associated with the operation of such suction rolls.
According to the invention a web is carried by a wire to a detaching location where the web is detached from the wire without the use of a separate pick-up suction roll and is transported to a press section of a paper machine. A transfer felt travels to the detaching location to engage the web at the latter location. More particularly, the forming wire carry~
ing the web is directed onto a sector of a detachment transfer roll.
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A relatively dry transfer ~elt is ccnducted onto the web on the de-`lchment transfer roll sector. This transfer elt also functions as a press felt operating in one or several nips of the press section. The web is detached from the wire and trans- -~
ferred to the ~elt by virtue of adhesion forces of the felt and the centrifugal force acting on the web while it travels on the detachment transfer roll sector. With the web thus adhering to the surface of the felt, the latter travels to the first press nip of a press section for dewatering, this latter nip being a double-felted nip where the transfer ~elt itself forms the upper felt of the double-felted press nip.
At the region of the first press nip the web is acted upon by suction provided by a press suction roll to assure retaining the web in engagement with the transfer elt which together with the web travels beyond the first press nip to a second press nip of the press section, this second press nip being formed by said suction roll and a smooth-surraced roll o the press section.
The present invention is particularly applicable to modern twin-wire formers which offer greater possibilities, as compared with Fourdrinier wire sections, for selection of the detaching location in such a way that the advantageous web-detachment of the present invention can be applied.
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': , ~71;L7 At the stage where the transfer felt and the web hering thereto arrive at the first press nip, where the transfer felt in the particular application of the present invention laps the upper roll of the first press nip, which is a suction roll, centrifugal force at this upper roll of the first press nip may tend to induce the web to become detached from the downwardly directed lower surface of the felt~ In order to avoid such an occurrence, with the invention the suction zone of the upper press roll at the first press nip is extended to a location in advance of the first press nip s-o that the web is reliably main~ained ad-hering to the transfer felt as the latter approaches the first press nip while curving around the press roll. At the same time, the so-called blowing phenomenon is avoided. In other words, detach-ment of the web from the felt owing to the phenomenon that in the thxoat formed by the pick-up or transfer felt and the surface of the suction roll a pressure is generated by the effect of air which the felt and the roll surface include between themselves.
An important feature of the invention is that the detachment of the web from the wire occurs at the detachment trans- ~ ~;
fer roll where the carrying wire travels over a sector thereof greater than 90, the wire and web thereon undergoing a sub-stantial change of direction of travel. The centrifugal force arising from this substantial change of direction assists in the detachment of the web from the wire so that the suction force re-quired to transfer the web from the wire to the felt can be minimized.
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The extent of the above substantial change in the direction of travel of the wire and the magnitude of the centrifugal force resulting therefrom depends upon the diameter of the roll around which the wire is guided as well as the machine speed.
If the machine operates at high speed, then even a relatively minor change in direction may be considered as being sub- ~ -stantial in the sense that under these conditions there will still be a tendency of the web tv become detached from the wire as a result of centrifugal force. At a given machine speed, the centriugal force created at a relatively small diameter roll is higher than that produced by a larger diameter .
roll, the centri~ugal force being inversely proportional to the radius of such a roll.
A number of guide rolls are provided for the transfer felt which are appropriately located so that the felt encircles a segment of the suction roll of the press as well as covering the sector of the detachment transfer roll as described above.
In one embodiment of the invention, the detachment transfer roll is located on substantially the same level as and in nip contact with the suction roll of the press section. As mentioned above, the press section suction roll is provided with a suction sector.
In this embodimenL, the suction sector is of sufficient extent such that it operatively extends into the transfer nip thereby facilitating detachment of the web from the wire as well as into first and second press nips. Since this suction sector on the press suction roll is covered both by the felt and the web adhering thereto, the amount of air passing therethrough, ~97~7 ~97~l7 i.e., the required suction energy, is not unduly large.
Thus, in this embodim~nt the suction sector of the press suction roll contributes to the detachment of the web ~rom the wire, serves to affix the web to the felt, aids in the dewatering in the first nip of the press, detaches the web from the lower felt o~ the first press nip and assists in the dewatering of the second nip.
BRIEF DESCRIPTICN OF DRAWINGS
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The invention is illustrated by way of example in the aecompanying drawings which form part o this application and in whic,h: -FIG. 1 is a schematie illustration of a machine aceording to the invention for carrying out the method of the invention, FIG. 1 illustrating a twin-wire former having one of its wires transporting the web to the detaching loeation with FIG. 1 showing not only how the web is detached from the wire at the detaching location but also how the web is then transported through the press section which is illustrated also in FIG. 1:
FIG. lA is a schematic illustration of the detachment transfer roll of the pxesent invention;
FIG. 2 is a sehematic illustration of another embodiment of a machine according to the invention, the structure at the region of detaching location being different in FIG. 2 from that illustrated in FIG. l;
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FIG. 3 is a fragmentary sectionaL schematic illus~ration of the detachment transfer roll of the present invention;
FIG. 4 is a fragmentary sectional schematic illustration of another embodiment of the detachment transfer roll of the present invention; and FIG. 5 is a fragmentary sectional schematic illustration `
of a detachment transfer roll according to the embodiment shown in FIG. 2, i.e., mounted in connection with the press suction roll.
DESCRIPTION OF PREFERRED EMBODIME~TS
Referring first to FIG. 1, there is schematically illustrated therein the web-forming section as well as the press section of a paper machine. The web-forming section includes a pair o endless wire loops 10 and 20 which have portions travelling upwardly aLong a common path to provide in this way a twin-wire former. The wire 10 is guided by way of the rolls 12 and also engages a guide roll 13 situated at an intermediate location along the path of common travel of the twin wires. In addition, this particular wire 10 laps the breast roll 11 to form a single-wire portion receiving pulp stock from the headbox 14. The twin-wire former includes a lower forming roll 21, and a forming board 15 engages the single-wire portion extending from the breast roll 11 to the lower forming roll 21. The forming board 15 has either a solid wall ' ~
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or a p~rforated wall engaging the wire 10. The lower forming roll 21, which is situated within the wire loop 20 has a suction zone 21a in the region in which dewatering of the web takes place. This dewatering tak~s place simultaneously in opposed directions, namely outwardly away from the roll 21 as a re-sult of centri~ugal force and inwardly toward the latter through the suction zone 21a. The wires 10 and 20 travel along a common path upwardly beyond the lower forming roll 21, while ~eing guided by the intermediate roll 13, to an upper forming roll or couch roll 22 provided with a suction zone 22a which assures that the web W which is formed, when travelling beyond the twin-wire forming path, will ccntinue to be transported by the wire 20 toward the right beyond the upper forming roll 22, as viewed in FIG. 1. The wire 20 is guided by way of suitable guide rolls 23.
The detaching of the web W from the carrying wire 20 is accomplished upon the wire engaging a cletachment trans~er roll 25. Referring to FIG. 1 in conjuncti.on with FIG. lA, the wire 20 engages a sector of detachment transfer roll 25 designated ~ which is somewhat larger than 90 . Transfer felt 30 is directed against detachment transfer roll 25 along a sector, designated c~ within sector ~. Thus, in sec~or c~ , there is a sandwich structure comprising carrying wire 20, the web W and the felt 30. The final detachment of web W from wire 20 as well as the attachment of web W to felt 30 occurs within . . .
: . , :lL09713l.r~7 sector ~ of detachment transfer roll 25. It should be noted ~' that web W actually begins detachiny from wire 20 prior to ~;
enyagement with sector ~ by virtue of the e~fect of the ~entrifugal force acting on we~ W in the sector designnted ~ o where the direction of the web carrying wire 20 first begins to change. This prede~achment is actually a partial liberation of the web from the wire although contact between the web and wire is maintained in sector~O.
In actual practice, the time interval wherein web W
detaches from wire 20 is the same time interval during which wire 20 is in contact with the detachment transfer roll 25, namely the time it takes for a se~ment o~E wire 20 to traverse sector ~ of roll 25. This detachment time is quite short.
Thus, for example, if the velocity of wire 20 is 900 m per minute and the diameter of detachment transfer roll 25 is 760 mm and the combined extent of sectors~BO and ~ is gO , the de-tachment of the web W from the wire 20 must occur in approximately 0.04 seconds. Further, it is evident that the time in which the web W becomes attached to the felt 30 is the time in which a portion of felt 30 traverses sector ~ on detachment transfer roll 25 and, in the example given, is about 0.02 seconds.
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The transfer felt 30 is guided by way of guide rolls 32, and a conditioning apparatus 33 is provided for the felt 33 as well as a washing press which has the rolls 33a and 33b. As is indicated schematically in FIGS 1 and 2, the particular guider~ll 32a is adjustable so that the transfer felt 30 can be guided to the detachment transfer roll in such a way that the felt 30 will cover the wire 20 and the web W
thereon over an area or sector ~ of a suitable magnitude.
In this way the attaching of the web W to the transfer felt 30 can be enhanced by increasing the extent of sector ~ thereby increasing the contact time of the felt 30 with web W and, thereore, maximizing the time for attachement of web W thereto.
The detachment of web W from wire 20 may alqo be promoted by increasing the time which wire 20 is in contact with the de-tachment transfer roll 25, i.e., by increasing the extent of sector ~. This may be accomplished by locating detachment trans-fer roll 25 substantially higher relative to couch roll 22 than is shown in FIG~ 1. For example, if detachment transfer roll 25 is upwardly displaced to a position higher than is shown in FIG. 1 so that wire 20 travels at an angle of 30 upwardly relative to the horizontal, the sector ,Bo ~ ~ in which the web is detached from wire 20 increases from 100 to 130 , that is,an increase of from 3C%~ resulting in a corresponding increase in the time in which web W is engaged on detachment transfer roll 25.
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The detachment of web W from wire 20 may also be facilitated by the provision of blowing means in cooperation with sec~ors,B and G~J . Such blowing means requires that the shell of detachment transfer roll 25 be foraminous. Two examples of the provision of such blowing means are illustrated in FIGS. 3 and 4, discussed belo~. Essentially, the blowing means provide a pressure differential which tends to detach the web from wire 20 and promote the webs attachment to the felt 30.
Additionally, a similar blowing effect tending to detach~
web W from wire 20 may be provided by a foil strip 26 ~FIG. 1), located at a suitable point adjacent to wire 20 in advance of detachment transfer roll 25. Thus, at high machine speeds, foil strip 26 produces an overpressure in the throat between the foil strip 26 and wire 20 which tends to initiate ~etachment of web W from the wire even before the web carrying wire reaches the detachment transfer roll 2S. Thus, it is possible to utilize a differential pressure prior to the application o the centrifugal forces by the detachment transfer roll 25 as well as during and after the application of such forces.
As is apparent from FIGS. 1 and 2, the transfer felt 30 simulteneously serves as the upper felt at the first press nip Nl of the press section of the paper machine. This first press nip is defined between press rolls 31 and 41, and the lower roll 41 is a water-accepting roll having a surface which is suitabl~ recessed for this purpose. This lower roll 41 has its own felt loop 40 which is guided by way of guide rolls 42 and -la-:'' ' '` '.:
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which is provided with a conditioning means 43. The upper roll 31 .~ the first press nip Nl is a suction roll and is provided with a suction sector having one or more compartments 34a, 34b.
The initial suction zone 34a extends in advance of the press nip Nl to such an extent that any possible detachment of the web W from the felt 30 as a result, for example, of centrifugal force will be prevented. By providing the roll 31 with a plurality of suction sectors such as the sectors 34a, 34b, it is possible to minimize the required suction capacity.
It is advantageous from the viewpoint o minimizing the required suction capacity to form the suction sector 34 in a continuous manner since if the holes of the suction roll 31 are filled with air between the suction compartments, an additional unnecessary load is exerted on the suction system.
The press section further includes a smooth surfaced central roll 61 which togetner with the upper roll 31 of the irst press nip forms the second press nip N2, this roll 61 cooperating with a press roll 71 so as to define a third press nip N3. The roll 71 has a recessed surface capable of receiving water. This roll 71 has its own felt loop 70, guided by guide rolls 72, and a felt conditioner 73 cooperates with the felt loop 70. The smooth-suraced central press roll 61 is cleaned by a doctor blade 62. From the roll 61 the web is detached in a well known manner and while guided by a roll 74 tr~vels to the drying section of the machine.
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It will be noted that tlle wire 10 is guided by a guide roll 12 subsequent to the common path of travel of the wires 10 and 20, which is horizontally adjustable.
Referring now to FIG. 2, another embodiment of the present invention is depicted comprising a wire section and a press section substantially similar to that shown in the em-bodiment of FIG. 1. However, in the embodiment illustrated in FIG. 2, detachment transfer roll 25' is located on substantially the same horizontal level as the suction roll 31' of the press section, detachment transfer roll 25' and press suction roll 31' being contiguous and defining a transfer nip No in which web W
detaches from forming wire 20 and attaches to felt 30.
The transfer of web W from wire 20 to felt 30 is facilitated at least in part by the centrifugal force present by virtue of the change in direction of the web carrying wire 20 on detachment transfer roll 25' in a manner similar to the manner in FIG. 1. However, the transfer of web W to felt 30 is aided in the embodiment of FIG. 2 through the application of suction applied from suction sector 34a of press suction roll 31'.
As described below, should it be found that the combination of the centrifugal forc~s and the suction forces are not sufficient to accomplish the transfer of web W from wire 20 to felt 30, the detachment transfer roll 25' may be provided with blowing means as shown in FIGS. 3 and 4 to increase the pressure dif~erential required for the transfer. However, it is contemplated that .. . . .
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certain applications the centrifugal force and suction force will be sufficient and, in these cases, detachment transfer roll 25' may simply comprise a solid shell, either smooth or grooved.
Furth~r, the detachment and transfer of web W from wire 20 to felt 30 may be facilitated by the appropriate adjustment of the lineal pressure in the transfer nip No~
Turning now to FIGS. 3 and 4, two possible alternate constructions of detachment transfer roll 25 are illustrated.
In both cases, the detachment transfer roll 25 is provided with blowing means for facilitating the detachment of web W from wire 20 and the attachment of web W to felt 30, Thus, referring to FIG. 3, it is seen that the web carr~ing wire 20 engages the roll 25 and substantially changes its direction thereby giving rise to an outwardly directed centrifugal force tending to detach web W
from wire 20. Roll 25 is formed with a fc)raminous shell 25a having a bipartite blow chamber 27 defined by blow chambers 27a, 27b provided with sealing strips 28a, 28b and 28c. A source of compressed air 55 fluidly communicates with the interior of chamber 27b and, through an aperture 29 in the partition separating the adjacent blow chambers, communicates with blow chamber 27a.
The overpressure in compartment 27b is preferably higher than the overpressure in compartment 27a due to the throttling effect of aperture 29 and due to the fact that the felt 30 covers web W
adjacent compartment 27b~
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The sector defined between sealing strips 28a and 28c the detachment transfer roll 25 shown in FIG. 3 corresponds to the sectors ~ ~,Bo shown in FIG. lA while the sector de-fined between sealing strips28b and 28c correspondsto the sector ~ (FIG. lA) covered by the transfer felt 30. Thus, the over-pressure created by compartrnent 27a facilitates the detachment of web W from wire 20 while the overpressure provided by com-partment 27b, in addition to facilitating detachment, also facilitates attachment of web W to felt 30. Of course, the forces provided by the respective blowing compartments act simultaneously with the centrifugal forces created by the substantial change in direction of the web engaged on detachment transfer roll 25.
Referring now to FIG. 4, another embodiment of the detachment transfer roll 25 is shown. Roll 25 is defined by a foraminous shell 25a. However, rather than being provided with blow chambers as shown in FIG. 3, the detachment transfer roll 25 houses an arcuate shoe 29a. The rotation of roll 25 produces a clockwise circulating air flow and shoe 29a deines a throat K
through which the circulating air moves resulting in a blowing effect. In the case of the detachment transfer roll 25 shown in FIG. 4, the detachment of web W frcn wire 20 and its attachment to web 30 occurs in the sector ~' ~ ~ . Of course, centrifugal forces are acting concurrently on web W in addition to the blowing effect a~d the natural surface adhesion of web W
to felt 30, the latter of which is effective over sector :10~7~7 -18- ;
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:~97~7 ~he relative strength of each of these factors depends on the velocity of wire 20, on the diamete.r of detachment transfer roll 25 and on the adhesive forces of the felt 30 to the web W.
Still referring to FIG. 4, a source of water 29b may be provided to further facilitate detachment of web W from wire 20.
Thus, the water is sprayed from source 29b as a fine spray S onto the inner surface of roll 25 whereupon it is driven by centrifugal force through openings 25a in the shell of the roll onto the meshes of wire 20. The quantity of water is relatively minimal and does not adversely affect the moisture content of the web W.
Referring now to FIG, 5, the detachment transfer roll 25' is shown in a position contiguous with the suction roll 31' of the press section in a manner corresponding to the emhodiment of FIG. 2. The suction roll 31' is constructed of a foraminous shell and the mouth of an ex~ernal suction box 50 extends over the sector of suction roll 31' not covered by felt 30. A vacuum system 53 communicates with the interior of suctio,n box 50 creating a suction through perforations 31a of the suction roll which acts through ~elt 30 on the web W thereby facilitating the transfer of web W on~o felt 30. Seals 52 are provided on the edges of suction box 50 to confine the area of suction roll surface through whi.ch the suction is effective.
As shown in FIG. 5, the detachment transfer roll 25' and the suction roll 31' of the press together define a transfer nip N , ::
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prior to web W arriving at the transfer nip No, i.e. while it is still carried on ~Jire 20, a pre-detachment effect is pro-duced by the centrifugal forces created by the change in direction of the we~ carrying wire 20 as it is engaged by the detachment transfer roll 25' over the sector ~O. This centrifugal force is denoted by Fo. Tnus, the transfer of web W onto felt 30 occurs on sector ~ of detachment transfer roll 25', which sector is fairly small.
Referring now to FIGS. 1 and 2, the headbox 14 of course supplies pulp stock to the wire 1~ to be delivered to the twin-wire former with water escaping to some extent at the forming ~oard 15 in advance of the forming roll 21 although dewatering primarily takes place at the forming roll 21. The detatering continues at a lesser rate at the guide roll 13 with some dewatering also taking place at the couch roll 22. The suction sector 22a of the roll 22 causes the web W to remain attached to the wire 20 so as to be carried thereby to the detachment transfer roll 25 (25' in FIG. 2). At the latter location the transfer felt 30, which also forms part of the press section, contacts the web W so that it is detached from wire 20 and adheres to the felt 30 as described hereinabove.
The web W which is attached to the felt 30, travels with the felt 30 to the first press nip Nl for dewatering. Thus the first press nip is defined between the upper suction roll 31 (31' in FIG. 2) within the transfer felt loop and the lower press roll 41 which is a water-accepting roll having a ~97~
suitably grooved surface, for example. This roll 41 of course has its own felt 40. Subsequent to the first press nip the web W remains attached to the felt 30 as a result of the suction prevail-ing at the zone 34 of the suction roll 31, and thus the web is transferred with the felt 30 to the second press nip N .
At the second press nip N2, defined between the roll 31 (31' in FIG 2) and the smooth-surface roll 61 which forms the central roll of the press section, the felt 30 also i5 compressed together with the web W, but at this point the web W becomes detached from the felt 30 adheres to the surface of roll 61, and travels together with the roll 61 to the third press nip N3.
This third press nip N3 is provided by situating in cooperation with the roll 61 a water-accepting roll 71 which has its own felt loop 70, as pointed out above. This roll 71 is also a roll such as a grooved roll capable of accepting water, and at the third press nip N3 the web is further dewatered so that the dry matter content thereof increases.
The web however still adheres to the smooth-surface roll 61 and subsequent to the third press nip N3 there may still be one more press nip although such an additional press nip has not been illustrated. Instead the web W has been shown as being detached from the roll 61 in a conventional manner, as a result of the differential speed, and it is then transpoxted to the drying section of the paper machine which ;~
in itself is well known.
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FrOm the foregoing it is apparent that an important feature of the present invention ls that the transfer felt 30, which also functions as a pressing felt, can be maintained in a relatively dry condition. Of course, this fact enhances the de-watering of the web in the press section. The transfer felt 30 can be maintained in its relatively dry condition since the attachment of the web W to felt 30 and its subsequent adherence thereto does not depend on water film adhesion as is common ~in prior art apparatus. Thus, referring to FIG. 1, there are no gravitational forces acting to detach web W from felt 30 since the web is maintained on the upwardly facing surface of the felt in its travel between detachment.transfer roll 25 and suction roll 31. Upon reaching the suction roll 31, there is still no need for water film adhesion since the web W is main-tained on felt 30 through the suction supplied by press suction ;~
roll 31.
As mentioned ahove, ~ view o its operation in drycondition, felt 30 is provided with felt conditioning means 33 ~nd, urtherO pressing means 33a, 33b. Additionally, in view of its operation in a dry condition, it is now possible to select a particular type of felt for felt 30 which is most favorable from the viewpoint of the pressing or dewatering process since the adhesion properties of the felt to the web are no longer of primary importance.
: ~ ', , , ~971~j Thus, the principles of operation and the advantages G_;ived therefrom of the presant invention can be summarized as follows. An important advantage of the invention is that the felt 30 oper~tes in a relatively dry condition. This is made possible by the fact that subsequent to web W being transferred from wire 20 onto felt 30, the web carrying felt, as shown in ~IG. 1, travels under an "excess ang]e" ~ with respect to the vertical until it reaches suction sector 34a of press suction roll 31. This is in contradistinction to prior art apparatus where it has been conventional for the web to "hang" on the downwardly facing surface of the felt thereby requiring a higher water content for the felt in order to obtain sufficient adhesion to the web.
However, in the present invention, the web carrying felt 30 travels in a substantially vertical direction or even under "excess angle"
~ from the detachment transfer roll 25 to the first press nip, thereby negating any gravity effect which would tend to promote detachment of the web from the felt. Another advantage of the present invention is that by providing a large or substantial change in direction to the web ~arrying wire 20, detachment of the web from the wire and its sub~equent attachment to the felt is facilitated. More particularly, by directing wire 20 over a relatively large sector ~ of detachment transfer roll 25, a correspondingly large detachment sector ~O t ~ is obtained where the centrifugal forces promote detachment of the web from the wire and attachment to the felt. Of course, this is in addition to the natural gravity forces which promote adhesion of the web ~3 .
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-7~.7 tQ ~e felt resulting from the "excess angle" ~ which defines the direction of travel of the web carrying felt. Referring to FIGS. 2 and 5, the present invention allows for the immediate transfer of the web W to the suction sector 34 of press suction roll 31' at transfer nip No thereby insuring that the web ~
is maintained on the felt 30 or transport to the first press nip Nl .
It is evident from the above that another advantage offered by the present invention is that the detachment o~ the web from the wire and its transfer to the web to the felt may be optimized by varying any one or more of several different parameters.
Thus, assuming a particular velocity of web W and its moisture content at the point of transfer, the parameters available for variation to optimize the transfer include the radius R (R' in FIG. 2) of the detachment and transfer rol:L 25, the magnitude of the sectors~ 0~ ~ and ~ of roll 25 (as well as their relative sizes~, and the angle ~ . These parameters are selectively variable over a wide range for optimization of the web detachment and transfer. Further, in the case of the embodiment shown in FIGS. 2 and 5, the detachment and transfer of the web from the wire to the felt may be further controlled through the selection of the nip pressure in the transfer nip N . ~dditionally, the quality of the felt 30 may be selected with a view toward facilitating the detachment and transfer of the web as well as subsequent pressing operations as will be understood by those skilled in the art.
~09~1~7 Reerring to FIG. lA, predetachment of web W from wire 20 occurs on sector ~ ~ of detachment transfer roll 25 through the action of centrifugal force F , the magnitude of which per ~nit mass of the web is F - mv /R, as is well known. Subsequent to the predetachment interval, i.e., subsequent to travel over sector ~ o~ upon felt 30 coming into contact with web W, the transfer of web W to felt 30 begins. This is denoted by sector in FIG. lA. A centrifugal force F continues to act on web W
as it traverses over sector ~ , thereby moving the web towards felt 30.
It should be understood that the particular construction of the press section and of the members preceding it which serve to transpost web W may be varied from that shown in the Figures.
For example, in the embodiment of the invention illustrated in FIGS~ 2 and 5, the detachment transfer roll 25' and press SUCtlOn roll 31' may be located at a considerably higher level relative to couch roll 22 thereby increasing the interval where centrifugal forces act to promote de-tachment of the web as described above. Further, it is within the scope of the present invention to provide in the case of the emhodiment shown in FIG. 5 a conventional suction compartment within press suction roll 31' for further facilitating transfer of the web to the felt and for promoting dewatering in nips Nl and N2. Where external suction box 50 is employed, perforations 31a may be replaced with grooves extending around the outer surface of suction roll 31' along which the suction effect is directed throu~h felt 30 on web W.
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Seals 52 of suction box 50 may be constructed in a number of different ways~ With respect to the construction of suction roll 31' and its external suction box 50, reference is made to applicant's Canadian Patent No. 1,059,356.
It is understood that the invention is not limited with respect to the wire former apparatus shown in FIGS. 1 and 2 but, for example, can be used in connection with a conventional Fourdrinier wire section. Further, the invention is not limited to the particular design of the press section shown in FIGS. ;~
1 and 2 since it is possible to leave out one of the dewatering press nips Nl or N. Further, an equalizing nip without a felt may be provided in association with central roll 61 in place of N3. In connection with the embodiments shown in FIGS. 2 and 5, a source of steam or other overpressure may be provided in tne areas between nips No, Nl and N2 where the web is supported ~y Eelt 30 for promoting dewatering and the maintenance of the web on the felt. In this respect, reference is made to applicant's U.S. patent No. 4,163,688.
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~:1 26
In particular, the present invention relates to methods and machines of this type which are concerned with the detaching of the paper web ~rom the forming wire which may, for example, be a wire of a twin-wire former, with this wire t~ansporting the web beyond the wire section to the press section.
The invention relates in particular to a method and apparatus of the above type which are designed to transport the web without any open draw from the wire to the press seetion of the paper machine, so that the web is continuously supported as it travels from the wire to the press section.
A detachment transfer roll inside the foxmin wire loop is utilized for contributing toward detaching of the web from the wire and adhering the web to a felt which transports the web from the wire to the press section.
As is well known, the operations in connection with which a web, which has been formed on the wire of a paper machine, is detached from the wire and transferred to the press section is extremely important, having a great influence on the re~iability of the operation of the paper machine. In paper machines which operate at relatively low speeds, it is possible to utilize open draws resulting from a speed differential between the wire and press sections.
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However, with paper machines which operate at ~ h speeds or which are utilized in the manufacture of relatively thin and therefore low-strength paper, it is known that closed transfer systems, without any open draw, must be utilized, so that the web is continuously supported while it travels from the wire to the press section.
Systems of this latter type usually operate in such a manner that a transfer felt of the press section is guided into contact with the web on the wire. Such a transfer felt may be pres~ed by way of a rotating roll against the web on the wire so that the web adheres to the felt to become de-tached from the wire and to continue to be transported by the felt which then transports the web to the first press nip of the press section.
In general there are two main types of closed transfer systems. The simplest is the so-called lick-up transfer based on the capability of a wet "lic~-up" felt to adhere the paper web to its surface. The other type of closed transfer system is a vacuum pick-up system which developed from the first system. By providing at the transfer point a vacuum, it is possible to reliably bring about trans-fer of the web from the wire to the felt with the web adheriDg reliably to the felt. A vacuum type of pick-up system offers greater possibilities than the first system, particularly for example, with regard to the selection of the quality of the felt. Particularly in those cases where the transfer felt also operates as a press felt, several requirements are imposed on the transfer felt. These requirements include a requirement ~09~
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that the web must adhere reliably to the surface of tlle felt at the attaching location while on the other hand the felt ~nust function eficientl~ at tlle dewatering first press nip of the press section.
In order for the web to reliably adhere to the felt between the detaching location and the first press nip, it has heen conventional practice to use a relatively wet felt. How-ever, where the transfer felt has also been employed as the press felt, the wetness of the felt to promote web adhesion of course lessens the ability for dewatering the web at the first press nip.
Thus, from the viewpoint o maximum efficiency in dewatering, it is desirable to maintain the felt as dry as possible.
Vacuum picX-up systems utilizing separate pick-up suction roll have gained a wide use. However, such conventional systems are encumbered by a number of d~awbacks.
Thus, conventional suction rolls of the above type are expensive, requiring an individual driving motor and control system, and they are exceedingly noisy in operation.
Furthermore, such suction rolls consume a great deal of air, due not only to the fact that the air which passes through the web and felt also enters into the suction system but also due to the fact that the air arriving in the suction zone in the holes of the suction roll shell must be moved out of these holes once during each revolution of the shell.
The amount of such "hole air" may in large, fast running machines be twice or even three times the air quantity traversing the web. In addition, numerous difficulties result from ~;~971 7 ., 3 " : .
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the fact that proper seals must be maintained by sealing water at the suction box which forms part of the suction roll.
The detaching of the web from the wire in a con-ventional Fourdrinier machine utilizing a separate pick-up suction roll takes place at a location situated on the wire run between the couch roll and the traction roll. At this location the wire travels downwardly at an angle of approximately 45 with respect to a horizontal plane. This detaching location is determined by the usual construction of the wire section and press section and by their location with respect to each other.
Subsequent to the detachin~ location the picX-up felt and the web adhering thereto la~ the pick-up roll through an angle of about 45-90 , and then the felt and the web adhering thereto travel to the press section. This latter change in the direction of travel of the felt at the detaching location, caused by the above lapping of the pick-up roll by the felt, causes under some circumstances, such as high speed or an unsuitable felt, a tendency for the web to detach itself from the pick-up felt as a result of the action of centrifugal force~ In ~rder to counteract this latter tendency for detachment of the web from the felt while travelling on the pick-up roll,it is essential to provide the pick-up roll with a suction zone extending through a substantial distance beyond the detach-ing zone itself. ~n this way it is possi~le to insure that the we~ will remain adhering t~ the felt, but of course this reliability in the operation is obtained at the cost o~ a ~97~
considerable additional load on the suction system of the pick-up roll. As a result, the suction roll requires a capacity in addition to that which would be required if the t:asX of the suction roll were only to effect detachment of the web from the wire and adhering the web to the ~elt.
SUMMARY OF THF INVENTION
It is accordingly a primary object of the present invention to provide a method and a~paratus ca~able of accornplishing an effective transfer of the web from the wire to a transfer felt while utilizing kinetic energy of the rota1:ing structural elements of the wire section as well as o the web itself, while also making effective use o centrifugal force in various ways to contribute to detaching o the web from the wire and adhering thereof to the transfer felt while at the same time minimizing the number of re~uired suction rolls, the e~penditure particularly of suction energy, and the noise associated with the operation of such suction rolls.
According to the invention a web is carried by a wire to a detaching location where the web is detached from the wire without the use of a separate pick-up suction roll and is transported to a press section of a paper machine. A transfer felt travels to the detaching location to engage the web at the latter location. More particularly, the forming wire carry~
ing the web is directed onto a sector of a detachment transfer roll.
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A relatively dry transfer ~elt is ccnducted onto the web on the de-`lchment transfer roll sector. This transfer elt also functions as a press felt operating in one or several nips of the press section. The web is detached from the wire and trans- -~
ferred to the ~elt by virtue of adhesion forces of the felt and the centrifugal force acting on the web while it travels on the detachment transfer roll sector. With the web thus adhering to the surface of the felt, the latter travels to the first press nip of a press section for dewatering, this latter nip being a double-felted nip where the transfer ~elt itself forms the upper felt of the double-felted press nip.
At the region of the first press nip the web is acted upon by suction provided by a press suction roll to assure retaining the web in engagement with the transfer elt which together with the web travels beyond the first press nip to a second press nip of the press section, this second press nip being formed by said suction roll and a smooth-surraced roll o the press section.
The present invention is particularly applicable to modern twin-wire formers which offer greater possibilities, as compared with Fourdrinier wire sections, for selection of the detaching location in such a way that the advantageous web-detachment of the present invention can be applied.
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': , ~71;L7 At the stage where the transfer felt and the web hering thereto arrive at the first press nip, where the transfer felt in the particular application of the present invention laps the upper roll of the first press nip, which is a suction roll, centrifugal force at this upper roll of the first press nip may tend to induce the web to become detached from the downwardly directed lower surface of the felt~ In order to avoid such an occurrence, with the invention the suction zone of the upper press roll at the first press nip is extended to a location in advance of the first press nip s-o that the web is reliably main~ained ad-hering to the transfer felt as the latter approaches the first press nip while curving around the press roll. At the same time, the so-called blowing phenomenon is avoided. In other words, detach-ment of the web from the felt owing to the phenomenon that in the thxoat formed by the pick-up or transfer felt and the surface of the suction roll a pressure is generated by the effect of air which the felt and the roll surface include between themselves.
An important feature of the invention is that the detachment of the web from the wire occurs at the detachment trans- ~ ~;
fer roll where the carrying wire travels over a sector thereof greater than 90, the wire and web thereon undergoing a sub-stantial change of direction of travel. The centrifugal force arising from this substantial change of direction assists in the detachment of the web from the wire so that the suction force re-quired to transfer the web from the wire to the felt can be minimized.
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The extent of the above substantial change in the direction of travel of the wire and the magnitude of the centrifugal force resulting therefrom depends upon the diameter of the roll around which the wire is guided as well as the machine speed.
If the machine operates at high speed, then even a relatively minor change in direction may be considered as being sub- ~ -stantial in the sense that under these conditions there will still be a tendency of the web tv become detached from the wire as a result of centrifugal force. At a given machine speed, the centriugal force created at a relatively small diameter roll is higher than that produced by a larger diameter .
roll, the centri~ugal force being inversely proportional to the radius of such a roll.
A number of guide rolls are provided for the transfer felt which are appropriately located so that the felt encircles a segment of the suction roll of the press as well as covering the sector of the detachment transfer roll as described above.
In one embodiment of the invention, the detachment transfer roll is located on substantially the same level as and in nip contact with the suction roll of the press section. As mentioned above, the press section suction roll is provided with a suction sector.
In this embodimenL, the suction sector is of sufficient extent such that it operatively extends into the transfer nip thereby facilitating detachment of the web from the wire as well as into first and second press nips. Since this suction sector on the press suction roll is covered both by the felt and the web adhering thereto, the amount of air passing therethrough, ~97~7 ~97~l7 i.e., the required suction energy, is not unduly large.
Thus, in this embodim~nt the suction sector of the press suction roll contributes to the detachment of the web ~rom the wire, serves to affix the web to the felt, aids in the dewatering in the first nip of the press, detaches the web from the lower felt o~ the first press nip and assists in the dewatering of the second nip.
BRIEF DESCRIPTICN OF DRAWINGS
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The invention is illustrated by way of example in the aecompanying drawings which form part o this application and in whic,h: -FIG. 1 is a schematie illustration of a machine aceording to the invention for carrying out the method of the invention, FIG. 1 illustrating a twin-wire former having one of its wires transporting the web to the detaching loeation with FIG. 1 showing not only how the web is detached from the wire at the detaching location but also how the web is then transported through the press section which is illustrated also in FIG. 1:
FIG. lA is a schematic illustration of the detachment transfer roll of the pxesent invention;
FIG. 2 is a sehematic illustration of another embodiment of a machine according to the invention, the structure at the region of detaching location being different in FIG. 2 from that illustrated in FIG. l;
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FIG. 3 is a fragmentary sectionaL schematic illus~ration of the detachment transfer roll of the present invention;
FIG. 4 is a fragmentary sectional schematic illustration of another embodiment of the detachment transfer roll of the present invention; and FIG. 5 is a fragmentary sectional schematic illustration `
of a detachment transfer roll according to the embodiment shown in FIG. 2, i.e., mounted in connection with the press suction roll.
DESCRIPTION OF PREFERRED EMBODIME~TS
Referring first to FIG. 1, there is schematically illustrated therein the web-forming section as well as the press section of a paper machine. The web-forming section includes a pair o endless wire loops 10 and 20 which have portions travelling upwardly aLong a common path to provide in this way a twin-wire former. The wire 10 is guided by way of the rolls 12 and also engages a guide roll 13 situated at an intermediate location along the path of common travel of the twin wires. In addition, this particular wire 10 laps the breast roll 11 to form a single-wire portion receiving pulp stock from the headbox 14. The twin-wire former includes a lower forming roll 21, and a forming board 15 engages the single-wire portion extending from the breast roll 11 to the lower forming roll 21. The forming board 15 has either a solid wall ' ~
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or a p~rforated wall engaging the wire 10. The lower forming roll 21, which is situated within the wire loop 20 has a suction zone 21a in the region in which dewatering of the web takes place. This dewatering tak~s place simultaneously in opposed directions, namely outwardly away from the roll 21 as a re-sult of centri~ugal force and inwardly toward the latter through the suction zone 21a. The wires 10 and 20 travel along a common path upwardly beyond the lower forming roll 21, while ~eing guided by the intermediate roll 13, to an upper forming roll or couch roll 22 provided with a suction zone 22a which assures that the web W which is formed, when travelling beyond the twin-wire forming path, will ccntinue to be transported by the wire 20 toward the right beyond the upper forming roll 22, as viewed in FIG. 1. The wire 20 is guided by way of suitable guide rolls 23.
The detaching of the web W from the carrying wire 20 is accomplished upon the wire engaging a cletachment trans~er roll 25. Referring to FIG. 1 in conjuncti.on with FIG. lA, the wire 20 engages a sector of detachment transfer roll 25 designated ~ which is somewhat larger than 90 . Transfer felt 30 is directed against detachment transfer roll 25 along a sector, designated c~ within sector ~. Thus, in sec~or c~ , there is a sandwich structure comprising carrying wire 20, the web W and the felt 30. The final detachment of web W from wire 20 as well as the attachment of web W to felt 30 occurs within . . .
: . , :lL09713l.r~7 sector ~ of detachment transfer roll 25. It should be noted ~' that web W actually begins detachiny from wire 20 prior to ~;
enyagement with sector ~ by virtue of the e~fect of the ~entrifugal force acting on we~ W in the sector designnted ~ o where the direction of the web carrying wire 20 first begins to change. This prede~achment is actually a partial liberation of the web from the wire although contact between the web and wire is maintained in sector~O.
In actual practice, the time interval wherein web W
detaches from wire 20 is the same time interval during which wire 20 is in contact with the detachment transfer roll 25, namely the time it takes for a se~ment o~E wire 20 to traverse sector ~ of roll 25. This detachment time is quite short.
Thus, for example, if the velocity of wire 20 is 900 m per minute and the diameter of detachment transfer roll 25 is 760 mm and the combined extent of sectors~BO and ~ is gO , the de-tachment of the web W from the wire 20 must occur in approximately 0.04 seconds. Further, it is evident that the time in which the web W becomes attached to the felt 30 is the time in which a portion of felt 30 traverses sector ~ on detachment transfer roll 25 and, in the example given, is about 0.02 seconds.
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The transfer felt 30 is guided by way of guide rolls 32, and a conditioning apparatus 33 is provided for the felt 33 as well as a washing press which has the rolls 33a and 33b. As is indicated schematically in FIGS 1 and 2, the particular guider~ll 32a is adjustable so that the transfer felt 30 can be guided to the detachment transfer roll in such a way that the felt 30 will cover the wire 20 and the web W
thereon over an area or sector ~ of a suitable magnitude.
In this way the attaching of the web W to the transfer felt 30 can be enhanced by increasing the extent of sector ~ thereby increasing the contact time of the felt 30 with web W and, thereore, maximizing the time for attachement of web W thereto.
The detachment of web W from wire 20 may alqo be promoted by increasing the time which wire 20 is in contact with the de-tachment transfer roll 25, i.e., by increasing the extent of sector ~. This may be accomplished by locating detachment trans-fer roll 25 substantially higher relative to couch roll 22 than is shown in FIG~ 1. For example, if detachment transfer roll 25 is upwardly displaced to a position higher than is shown in FIG. 1 so that wire 20 travels at an angle of 30 upwardly relative to the horizontal, the sector ,Bo ~ ~ in which the web is detached from wire 20 increases from 100 to 130 , that is,an increase of from 3C%~ resulting in a corresponding increase in the time in which web W is engaged on detachment transfer roll 25.
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The detachment of web W from wire 20 may also be facilitated by the provision of blowing means in cooperation with sec~ors,B and G~J . Such blowing means requires that the shell of detachment transfer roll 25 be foraminous. Two examples of the provision of such blowing means are illustrated in FIGS. 3 and 4, discussed belo~. Essentially, the blowing means provide a pressure differential which tends to detach the web from wire 20 and promote the webs attachment to the felt 30.
Additionally, a similar blowing effect tending to detach~
web W from wire 20 may be provided by a foil strip 26 ~FIG. 1), located at a suitable point adjacent to wire 20 in advance of detachment transfer roll 25. Thus, at high machine speeds, foil strip 26 produces an overpressure in the throat between the foil strip 26 and wire 20 which tends to initiate ~etachment of web W from the wire even before the web carrying wire reaches the detachment transfer roll 2S. Thus, it is possible to utilize a differential pressure prior to the application o the centrifugal forces by the detachment transfer roll 25 as well as during and after the application of such forces.
As is apparent from FIGS. 1 and 2, the transfer felt 30 simulteneously serves as the upper felt at the first press nip Nl of the press section of the paper machine. This first press nip is defined between press rolls 31 and 41, and the lower roll 41 is a water-accepting roll having a surface which is suitabl~ recessed for this purpose. This lower roll 41 has its own felt loop 40 which is guided by way of guide rolls 42 and -la-:'' ' '` '.:
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which is provided with a conditioning means 43. The upper roll 31 .~ the first press nip Nl is a suction roll and is provided with a suction sector having one or more compartments 34a, 34b.
The initial suction zone 34a extends in advance of the press nip Nl to such an extent that any possible detachment of the web W from the felt 30 as a result, for example, of centrifugal force will be prevented. By providing the roll 31 with a plurality of suction sectors such as the sectors 34a, 34b, it is possible to minimize the required suction capacity.
It is advantageous from the viewpoint o minimizing the required suction capacity to form the suction sector 34 in a continuous manner since if the holes of the suction roll 31 are filled with air between the suction compartments, an additional unnecessary load is exerted on the suction system.
The press section further includes a smooth surfaced central roll 61 which togetner with the upper roll 31 of the irst press nip forms the second press nip N2, this roll 61 cooperating with a press roll 71 so as to define a third press nip N3. The roll 71 has a recessed surface capable of receiving water. This roll 71 has its own felt loop 70, guided by guide rolls 72, and a felt conditioner 73 cooperates with the felt loop 70. The smooth-suraced central press roll 61 is cleaned by a doctor blade 62. From the roll 61 the web is detached in a well known manner and while guided by a roll 74 tr~vels to the drying section of the machine.
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It will be noted that tlle wire 10 is guided by a guide roll 12 subsequent to the common path of travel of the wires 10 and 20, which is horizontally adjustable.
Referring now to FIG. 2, another embodiment of the present invention is depicted comprising a wire section and a press section substantially similar to that shown in the em-bodiment of FIG. 1. However, in the embodiment illustrated in FIG. 2, detachment transfer roll 25' is located on substantially the same horizontal level as the suction roll 31' of the press section, detachment transfer roll 25' and press suction roll 31' being contiguous and defining a transfer nip No in which web W
detaches from forming wire 20 and attaches to felt 30.
The transfer of web W from wire 20 to felt 30 is facilitated at least in part by the centrifugal force present by virtue of the change in direction of the web carrying wire 20 on detachment transfer roll 25' in a manner similar to the manner in FIG. 1. However, the transfer of web W to felt 30 is aided in the embodiment of FIG. 2 through the application of suction applied from suction sector 34a of press suction roll 31'.
As described below, should it be found that the combination of the centrifugal forc~s and the suction forces are not sufficient to accomplish the transfer of web W from wire 20 to felt 30, the detachment transfer roll 25' may be provided with blowing means as shown in FIGS. 3 and 4 to increase the pressure dif~erential required for the transfer. However, it is contemplated that .. . . .
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certain applications the centrifugal force and suction force will be sufficient and, in these cases, detachment transfer roll 25' may simply comprise a solid shell, either smooth or grooved.
Furth~r, the detachment and transfer of web W from wire 20 to felt 30 may be facilitated by the appropriate adjustment of the lineal pressure in the transfer nip No~
Turning now to FIGS. 3 and 4, two possible alternate constructions of detachment transfer roll 25 are illustrated.
In both cases, the detachment transfer roll 25 is provided with blowing means for facilitating the detachment of web W from wire 20 and the attachment of web W to felt 30, Thus, referring to FIG. 3, it is seen that the web carr~ing wire 20 engages the roll 25 and substantially changes its direction thereby giving rise to an outwardly directed centrifugal force tending to detach web W
from wire 20. Roll 25 is formed with a fc)raminous shell 25a having a bipartite blow chamber 27 defined by blow chambers 27a, 27b provided with sealing strips 28a, 28b and 28c. A source of compressed air 55 fluidly communicates with the interior of chamber 27b and, through an aperture 29 in the partition separating the adjacent blow chambers, communicates with blow chamber 27a.
The overpressure in compartment 27b is preferably higher than the overpressure in compartment 27a due to the throttling effect of aperture 29 and due to the fact that the felt 30 covers web W
adjacent compartment 27b~
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: . .
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The sector defined between sealing strips 28a and 28c the detachment transfer roll 25 shown in FIG. 3 corresponds to the sectors ~ ~,Bo shown in FIG. lA while the sector de-fined between sealing strips28b and 28c correspondsto the sector ~ (FIG. lA) covered by the transfer felt 30. Thus, the over-pressure created by compartrnent 27a facilitates the detachment of web W from wire 20 while the overpressure provided by com-partment 27b, in addition to facilitating detachment, also facilitates attachment of web W to felt 30. Of course, the forces provided by the respective blowing compartments act simultaneously with the centrifugal forces created by the substantial change in direction of the web engaged on detachment transfer roll 25.
Referring now to FIG. 4, another embodiment of the detachment transfer roll 25 is shown. Roll 25 is defined by a foraminous shell 25a. However, rather than being provided with blow chambers as shown in FIG. 3, the detachment transfer roll 25 houses an arcuate shoe 29a. The rotation of roll 25 produces a clockwise circulating air flow and shoe 29a deines a throat K
through which the circulating air moves resulting in a blowing effect. In the case of the detachment transfer roll 25 shown in FIG. 4, the detachment of web W frcn wire 20 and its attachment to web 30 occurs in the sector ~' ~ ~ . Of course, centrifugal forces are acting concurrently on web W in addition to the blowing effect a~d the natural surface adhesion of web W
to felt 30, the latter of which is effective over sector :10~7~7 -18- ;
;
.:: '.
:~97~7 ~he relative strength of each of these factors depends on the velocity of wire 20, on the diamete.r of detachment transfer roll 25 and on the adhesive forces of the felt 30 to the web W.
Still referring to FIG. 4, a source of water 29b may be provided to further facilitate detachment of web W from wire 20.
Thus, the water is sprayed from source 29b as a fine spray S onto the inner surface of roll 25 whereupon it is driven by centrifugal force through openings 25a in the shell of the roll onto the meshes of wire 20. The quantity of water is relatively minimal and does not adversely affect the moisture content of the web W.
Referring now to FIG, 5, the detachment transfer roll 25' is shown in a position contiguous with the suction roll 31' of the press section in a manner corresponding to the emhodiment of FIG. 2. The suction roll 31' is constructed of a foraminous shell and the mouth of an ex~ernal suction box 50 extends over the sector of suction roll 31' not covered by felt 30. A vacuum system 53 communicates with the interior of suctio,n box 50 creating a suction through perforations 31a of the suction roll which acts through ~elt 30 on the web W thereby facilitating the transfer of web W on~o felt 30. Seals 52 are provided on the edges of suction box 50 to confine the area of suction roll surface through whi.ch the suction is effective.
As shown in FIG. 5, the detachment transfer roll 25' and the suction roll 31' of the press together define a transfer nip N , ::
.. :-: , .
:: .: .:
' . ; ' : .
prior to web W arriving at the transfer nip No, i.e. while it is still carried on ~Jire 20, a pre-detachment effect is pro-duced by the centrifugal forces created by the change in direction of the we~ carrying wire 20 as it is engaged by the detachment transfer roll 25' over the sector ~O. This centrifugal force is denoted by Fo. Tnus, the transfer of web W onto felt 30 occurs on sector ~ of detachment transfer roll 25', which sector is fairly small.
Referring now to FIGS. 1 and 2, the headbox 14 of course supplies pulp stock to the wire 1~ to be delivered to the twin-wire former with water escaping to some extent at the forming ~oard 15 in advance of the forming roll 21 although dewatering primarily takes place at the forming roll 21. The detatering continues at a lesser rate at the guide roll 13 with some dewatering also taking place at the couch roll 22. The suction sector 22a of the roll 22 causes the web W to remain attached to the wire 20 so as to be carried thereby to the detachment transfer roll 25 (25' in FIG. 2). At the latter location the transfer felt 30, which also forms part of the press section, contacts the web W so that it is detached from wire 20 and adheres to the felt 30 as described hereinabove.
The web W which is attached to the felt 30, travels with the felt 30 to the first press nip Nl for dewatering. Thus the first press nip is defined between the upper suction roll 31 (31' in FIG. 2) within the transfer felt loop and the lower press roll 41 which is a water-accepting roll having a ~97~
suitably grooved surface, for example. This roll 41 of course has its own felt 40. Subsequent to the first press nip the web W remains attached to the felt 30 as a result of the suction prevail-ing at the zone 34 of the suction roll 31, and thus the web is transferred with the felt 30 to the second press nip N .
At the second press nip N2, defined between the roll 31 (31' in FIG 2) and the smooth-surface roll 61 which forms the central roll of the press section, the felt 30 also i5 compressed together with the web W, but at this point the web W becomes detached from the felt 30 adheres to the surface of roll 61, and travels together with the roll 61 to the third press nip N3.
This third press nip N3 is provided by situating in cooperation with the roll 61 a water-accepting roll 71 which has its own felt loop 70, as pointed out above. This roll 71 is also a roll such as a grooved roll capable of accepting water, and at the third press nip N3 the web is further dewatered so that the dry matter content thereof increases.
The web however still adheres to the smooth-surface roll 61 and subsequent to the third press nip N3 there may still be one more press nip although such an additional press nip has not been illustrated. Instead the web W has been shown as being detached from the roll 61 in a conventional manner, as a result of the differential speed, and it is then transpoxted to the drying section of the paper machine which ;~
in itself is well known.
: ;~, , :
,' ' : ' .~
3L~9711~
FrOm the foregoing it is apparent that an important feature of the present invention ls that the transfer felt 30, which also functions as a pressing felt, can be maintained in a relatively dry condition. Of course, this fact enhances the de-watering of the web in the press section. The transfer felt 30 can be maintained in its relatively dry condition since the attachment of the web W to felt 30 and its subsequent adherence thereto does not depend on water film adhesion as is common ~in prior art apparatus. Thus, referring to FIG. 1, there are no gravitational forces acting to detach web W from felt 30 since the web is maintained on the upwardly facing surface of the felt in its travel between detachment.transfer roll 25 and suction roll 31. Upon reaching the suction roll 31, there is still no need for water film adhesion since the web W is main-tained on felt 30 through the suction supplied by press suction ;~
roll 31.
As mentioned ahove, ~ view o its operation in drycondition, felt 30 is provided with felt conditioning means 33 ~nd, urtherO pressing means 33a, 33b. Additionally, in view of its operation in a dry condition, it is now possible to select a particular type of felt for felt 30 which is most favorable from the viewpoint of the pressing or dewatering process since the adhesion properties of the felt to the web are no longer of primary importance.
: ~ ', , , ~971~j Thus, the principles of operation and the advantages G_;ived therefrom of the presant invention can be summarized as follows. An important advantage of the invention is that the felt 30 oper~tes in a relatively dry condition. This is made possible by the fact that subsequent to web W being transferred from wire 20 onto felt 30, the web carrying felt, as shown in ~IG. 1, travels under an "excess ang]e" ~ with respect to the vertical until it reaches suction sector 34a of press suction roll 31. This is in contradistinction to prior art apparatus where it has been conventional for the web to "hang" on the downwardly facing surface of the felt thereby requiring a higher water content for the felt in order to obtain sufficient adhesion to the web.
However, in the present invention, the web carrying felt 30 travels in a substantially vertical direction or even under "excess angle"
~ from the detachment transfer roll 25 to the first press nip, thereby negating any gravity effect which would tend to promote detachment of the web from the felt. Another advantage of the present invention is that by providing a large or substantial change in direction to the web ~arrying wire 20, detachment of the web from the wire and its sub~equent attachment to the felt is facilitated. More particularly, by directing wire 20 over a relatively large sector ~ of detachment transfer roll 25, a correspondingly large detachment sector ~O t ~ is obtained where the centrifugal forces promote detachment of the web from the wire and attachment to the felt. Of course, this is in addition to the natural gravity forces which promote adhesion of the web ~3 .
'. : ', .. :;. .. :
. ...... ~ ,. .
-7~.7 tQ ~e felt resulting from the "excess angle" ~ which defines the direction of travel of the web carrying felt. Referring to FIGS. 2 and 5, the present invention allows for the immediate transfer of the web W to the suction sector 34 of press suction roll 31' at transfer nip No thereby insuring that the web ~
is maintained on the felt 30 or transport to the first press nip Nl .
It is evident from the above that another advantage offered by the present invention is that the detachment o~ the web from the wire and its transfer to the web to the felt may be optimized by varying any one or more of several different parameters.
Thus, assuming a particular velocity of web W and its moisture content at the point of transfer, the parameters available for variation to optimize the transfer include the radius R (R' in FIG. 2) of the detachment and transfer rol:L 25, the magnitude of the sectors~ 0~ ~ and ~ of roll 25 (as well as their relative sizes~, and the angle ~ . These parameters are selectively variable over a wide range for optimization of the web detachment and transfer. Further, in the case of the embodiment shown in FIGS. 2 and 5, the detachment and transfer of the web from the wire to the felt may be further controlled through the selection of the nip pressure in the transfer nip N . ~dditionally, the quality of the felt 30 may be selected with a view toward facilitating the detachment and transfer of the web as well as subsequent pressing operations as will be understood by those skilled in the art.
~09~1~7 Reerring to FIG. lA, predetachment of web W from wire 20 occurs on sector ~ ~ of detachment transfer roll 25 through the action of centrifugal force F , the magnitude of which per ~nit mass of the web is F - mv /R, as is well known. Subsequent to the predetachment interval, i.e., subsequent to travel over sector ~ o~ upon felt 30 coming into contact with web W, the transfer of web W to felt 30 begins. This is denoted by sector in FIG. lA. A centrifugal force F continues to act on web W
as it traverses over sector ~ , thereby moving the web towards felt 30.
It should be understood that the particular construction of the press section and of the members preceding it which serve to transpost web W may be varied from that shown in the Figures.
For example, in the embodiment of the invention illustrated in FIGS~ 2 and 5, the detachment transfer roll 25' and press SUCtlOn roll 31' may be located at a considerably higher level relative to couch roll 22 thereby increasing the interval where centrifugal forces act to promote de-tachment of the web as described above. Further, it is within the scope of the present invention to provide in the case of the emhodiment shown in FIG. 5 a conventional suction compartment within press suction roll 31' for further facilitating transfer of the web to the felt and for promoting dewatering in nips Nl and N2. Where external suction box 50 is employed, perforations 31a may be replaced with grooves extending around the outer surface of suction roll 31' along which the suction effect is directed throu~h felt 30 on web W.
::- . . . : - .
..
: . . . :: ,:
: '::~ ,. - .
. : ::
.,~ . :....... . . - .:
:lal97~1:1lr~
Seals 52 of suction box 50 may be constructed in a number of different ways~ With respect to the construction of suction roll 31' and its external suction box 50, reference is made to applicant's Canadian Patent No. 1,059,356.
It is understood that the invention is not limited with respect to the wire former apparatus shown in FIGS. 1 and 2 but, for example, can be used in connection with a conventional Fourdrinier wire section. Further, the invention is not limited to the particular design of the press section shown in FIGS. ;~
1 and 2 since it is possible to leave out one of the dewatering press nips Nl or N. Further, an equalizing nip without a felt may be provided in association with central roll 61 in place of N3. In connection with the embodiments shown in FIGS. 2 and 5, a source of steam or other overpressure may be provided in tne areas between nips No, Nl and N2 where the web is supported ~y Eelt 30 for promoting dewatering and the maintenance of the web on the felt. In this respect, reference is made to applicant's U.S. patent No. 4,163,688.
.
~:1 26
Claims (20)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for operating a paper manufacturing mach-ine wherein a web is detached from a forming wire loop and con-ducted to a press section of the machine by a transfer felt comprising the steps of conducting the web carrying forming wire into engagement with a first sector of a detachment transfer roll wrapped partly by said wire loop; conducting the transfer felt in a relatively dry condition into engagement with said web over a second sector following said first sector of the detachment trans-fer roll, said transfer felt also functioning as a pressing felt partially operating in at least one of the press nips in the press section; detaching said web from said forming wire and transferring it to said transfer felt under the action of centrifugal force and simultaneous adhesion forces causing said web to adhere to the outer side of the transfer felt; and transporting the web adhered on the transfer felt to the first dewatering press nip of the press section.
2. A method as claimed in claim 1 including the steps of providing a press suction roll contiguous with said detachment transfer roll defining a transfer nip at the second sector in which the wire detachment of the web from the wire and transfer to the felt occurs; and applying suction from said suction roll to said web at least in the transfer nip to facilitate said web detachment and adherence to said felt.
3. A method as claimed in claim 2 including the step of providing said press suction roll with at least one external suction compartment allowing said suction to be effective in said transfer nip and at least one of the press nips.
4. A method as claimed in claim 1 including the step of providing a press suction roll in the machine press section partially defining at least one dewatering press nip, and provid-ing at least one suction compartment inwardly in said press suc-tion roll and directing said suction onto the web before the web reaches said dewatering first press nip.
5. A method as claimed in claim 1 including the step of providing an overpressure in said transfer roll working in the same direction as the centrifugal force at said detachment transfer roll for facilitating the detachment of the web from the forming wire and its transfer to the felt.
6. A method as claimed in claim 5 wherein said over-pressure is obtained by providing at least one pressure means within the detachment transfer roll and openings in the surface of said roll for communication of said overpressure to said web.
7. A method as claimed in claim 5 wherein said over-pressure is obtained by providing a throat defining baffle with-in the detachment transfer roll and openings in the surface of said roll for communication of said overpressure to said web.
8. A method as claimed in claim 1 including the step of spraying water inwardly into the web forming wire to facili-tate detachment of the web therefrom.
9. A method as claimed in claim 1 including the step of applying an air pressure to said web forming wire prior to its engagement with the detachment transfer roll to facilitate predetachment of the web from the wire.
10. A method as claimed in claim 1 wherein said step of transporting said web carrying felt to the first press nip comprises moving the web carrying felt in a substantially verti-cal direction to the first press nip.
11. Apparatus in a paper manufacturing machine for detaching a web from a loop of forming wire and conducting the web to a press section of the machine by a transfer felt compris-ing: a detachment transfer roll wrapped partly by said web forming wire loop; means for conducting the web forming wire into engagement with a first sector of said detachment transfer roll; a transfer felt for transporting the web to the machine press section, said transfer felt further functioning as a press-ing felt in at least one of the press nips in the press section;
means for pressing said transfer felt to a relatively dry condi-tion before engaging the web over a second sector following said first sector of the detachment transfer roll; whereby said web detaches from the forming wire and is transferred to said felt under the action of the centrifugal force undergone by the web on the detachment transfer roll, said web adhering to the outer side of the felt by adhesion forces; and means for conducting the web carrying transfer felt to the first press nip of the press section.
means for pressing said transfer felt to a relatively dry condi-tion before engaging the web over a second sector following said first sector of the detachment transfer roll; whereby said web detaches from the forming wire and is transferred to said felt under the action of the centrifugal force undergone by the web on the detachment transfer roll, said web adhering to the outer side of the felt by adhesion forces; and means for conducting the web carrying transfer felt to the first press nip of the press section.
12. Apparatus as claimed in claim 11 wherein said first sector is greater than 90°.
13. Apparatus as claimed in claim 11 further including means for selectively adjusting the extent of said second sector.
14. Apparatus as claimed in claim 11 including a suc-tion roll located in said machine press section, said web carry-ing transfer felt being engaged with said press suction roll.
15. Apparatus as claimed in claim 14 wherein said detachment transfer roll is located at a vertically elevated position with respect to said press suction roll such that said web carrying felt travels in a substantially vertical direction from said detachment transfer roll to said press suction roll.
16. Apparatus as claimed in claim 15 wherein said direction of travel of said web carrying felt is at an acute angle with respect to the horizontal so that the web is carried on the upwardly facing surface of said felt.
17. Apparatus as claimed in claim 14 wherein said detachment transfer roll and said press suction roll are located contiguous with each other defining a transfer nip.
18. Apparatus as claimed in claim 17 wherein said press suction roll comprises a foraminous shell and further including a suction box located externally with respect to the shell of said press suction roll, said suction box being opera-tively associated with means for providing suction, said suction box directing suction to said web tending to facilitate transfer and adherence of said web to said felt.
19. Apparatus as claimed in claim 11 comprising a suction roll in said machine press section, said transfer felt engaging said press suction roll, a second press roll associated with a second felt loop, said press suction roll and said second press roll defining a first press nip; a central press roll having a substantially smooth surface, said central press roll and said press suction roll defining a second press nip;
a third press roll associated with a third felt loop, said third press roll and said central press roll defining a third press nip.
a third press roll associated with a third felt loop, said third press roll and said central press roll defining a third press nip.
20. Apparatus as recited in claim 17 wherein said press suction roll comprises a solid shell having a grooved sur-face and further including a suction box located externally with respect to the shell of said press suction roll, said suction box being operatively associated with means for providing suction, said suction box directing suction to said web tending facilitate transfer and adherence of said web to said felt.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI772990A FI772990A (en) | 1977-10-11 | 1977-10-11 | FOERFARANDE OCH ANORDNING I EN PAPPERSMASKIN FOER LOESGOERING AV BANAN FRAON FORMERINGSVIRAN OCH DESS FRAMLEDNING SOM SLUTEN OEVERFOERING TILL PAPPERSMASKINENS PRESSDEL |
| FI772990 | 1977-10-11 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1097117A true CA1097117A (en) | 1981-03-10 |
Family
ID=8511124
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA312,965A Expired CA1097117A (en) | 1977-10-11 | 1978-10-10 | Procedure and means in a paper machine for the detachment of the web from the forming wire and for its transfer in closed conduction to the press section of the paper machine |
Country Status (11)
| Country | Link |
|---|---|
| JP (1) | JPS5459413A (en) |
| AT (1) | ATA713078A (en) |
| BR (1) | BR7806551A (en) |
| CA (1) | CA1097117A (en) |
| DE (2) | DE7829628U1 (en) |
| FI (1) | FI772990A (en) |
| FR (1) | FR2406025A1 (en) |
| GB (1) | GB2006293B (en) |
| IT (1) | IT7828265A0 (en) |
| SE (1) | SE7810572L (en) |
| SU (1) | SU884577A3 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI60897C (en) * | 1978-06-16 | 1982-04-13 | Valmet Oy | FOERFARANDE OCH ANORDNING I EN PAPPERSMASKIN FOER LOESGOERING AV BANAN FRAON EN FORMNINGSVIRA OCH FOER OEVERFOERING AV DENSAMMA TILL EN TILL PRESSPARTIET HOERANDE VAEVNAD |
| DE19613390A1 (en) * | 1996-04-03 | 1997-10-09 | Voith Sulzer Papiermasch Gmbh | Roller press |
| DE102021121504A1 (en) | 2021-08-19 | 2023-02-23 | Voith Patent Gmbh | Machine and method for making a tissue web |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US1991346A (en) * | 1934-04-18 | 1935-02-12 | Downingtown Mfg Co | Press section for fourdrinier paper machines |
| US2204426A (en) * | 1935-06-21 | 1940-06-11 | Sandusky Foundry And Machine C | Papermaking machine |
| GB744084A (en) * | 1953-06-17 | 1956-02-01 | Millspaugh Ltd | Improvements in or relating to paper-making machines |
| DE1178691B (en) * | 1958-07-11 | 1964-09-24 | Doerries A G O | Device for transferring the paper web from the fourdrinier wire of a paper machine into the press section by means of compressed air |
| GB1530246A (en) * | 1976-04-14 | 1978-10-25 | Valmet Oy | Method of and means for detaching and conducting a paper web in a paper-making machine |
-
1977
- 1977-10-11 FI FI772990A patent/FI772990A/en unknown
-
1978
- 1978-09-29 IT IT7828265A patent/IT7828265A0/en unknown
- 1978-10-03 GB GB7839137A patent/GB2006293B/en not_active Expired
- 1978-10-03 BR BR7806551A patent/BR7806551A/en unknown
- 1978-10-03 AT AT0713078A patent/ATA713078A/en not_active Application Discontinuation
- 1978-10-04 DE DE19787829628U patent/DE7829628U1/en not_active Expired
- 1978-10-04 DE DE19782843288 patent/DE2843288A1/en not_active Ceased
- 1978-10-10 SE SE7810572A patent/SE7810572L/en unknown
- 1978-10-10 CA CA312,965A patent/CA1097117A/en not_active Expired
- 1978-10-10 SU SU782673557A patent/SU884577A3/en active
- 1978-10-11 FR FR7829054A patent/FR2406025A1/en active Pending
- 1978-10-11 JP JP12420378A patent/JPS5459413A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| GB2006293A (en) | 1979-05-02 |
| FR2406025A1 (en) | 1979-05-11 |
| JPS5459413A (en) | 1979-05-14 |
| BR7806551A (en) | 1979-05-08 |
| IT7828265A0 (en) | 1978-09-29 |
| FI772990A (en) | 1979-04-12 |
| SE7810572L (en) | 1979-04-12 |
| GB2006293B (en) | 1982-11-10 |
| DE7829628U1 (en) | 1982-04-29 |
| DE2843288A1 (en) | 1979-04-26 |
| ATA713078A (en) | 1983-04-15 |
| SU884577A3 (en) | 1981-11-23 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |