CA1181975A - Extended nip press - Google Patents
Extended nip pressInfo
- Publication number
- CA1181975A CA1181975A CA000398006A CA398006A CA1181975A CA 1181975 A CA1181975 A CA 1181975A CA 000398006 A CA000398006 A CA 000398006A CA 398006 A CA398006 A CA 398006A CA 1181975 A CA1181975 A CA 1181975A
- Authority
- CA
- Canada
- Prior art keywords
- nip
- web
- shoes
- shoe
- pressing
- 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
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F1/00—Wet end of machines for making continuous webs of paper
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F3/00—Press section of machines for making continuous webs of paper
- D21F3/02—Wet presses
- D21F3/0209—Wet presses with extended press nip
- D21F3/0218—Shoe presses
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B30—PRESSES
- B30B—PRESSES IN GENERAL
- B30B9/00—Presses specially adapted for particular purposes
- B30B9/02—Presses specially adapted for particular purposes for squeezing-out liquid from liquid-containing material, e.g. juice from fruits, oil from oil-containing material
- B30B9/24—Presses specially adapted for particular purposes for squeezing-out liquid from liquid-containing material, e.g. juice from fruits, oil from oil-containing material using an endless pressing band
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Paper (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A press mechanism for removing water from a traveling fibrous paper web including an elongate extended press nip formed between first and second pressing shoes each having a relieved leading edge with an elongate extending following pressing face, felts sandwiching the web in the nip, and traveling impervious belts sandwiching the felt and web there-between with the belts driven by a grooved traction roll and guide roll, and at least one of the shoes pivotally supported along its length and pressing force being applied to one of the shoes by a piston in a cylinder and pressurized fluid applied to the cylinder and piston to obtain the pressing force.
A press mechanism for removing water from a traveling fibrous paper web including an elongate extended press nip formed between first and second pressing shoes each having a relieved leading edge with an elongate extending following pressing face, felts sandwiching the web in the nip, and traveling impervious belts sandwiching the felt and web there-between with the belts driven by a grooved traction roll and guide roll, and at least one of the shoes pivotally supported along its length and pressing force being applied to one of the shoes by a piston in a cylinder and pressurized fluid applied to the cylinder and piston to obtain the pressing force.
Description
/
~3~
The inventlon relate~ to ~n improved method and mechan-ism ~or pressing wa~e~ rom ~ ~ravelin~ paper web, and more particularly to ~ pre~ arrangement know~ a~ an extended press nip wherein the web i6 sub3ect:ed to presslng pressures for a longer period of ~i~R than the usual arr~ngement wherein it pa~ses between two opposed pres~ roll&.
More par~icularly, the invention relates to a method and structure having a press nip wherein the residence time of the web in the nips iæ increased over tha~ of a roll couple and wherein an impro~ed structure is used to extract watPr from a web. Other structures have been provided heretofore which have attempted to increase the time over which a web is subjected to a pressure, and yet permit the web to continuP
movement at a speed necessary in a high ~peed papermaking machine. Such struc~ures have met with degrees of success and are exempli~ied by the disclosure~ of U.S. Pat. Nos. 3,748,225, Busker et al; 3,783,097, (Re. 30,268), Ju~tus; 3,797,384, Hoff, 3, 798, 121, Busker et al; 3, 804, 707, Mohr; 3, 808, 092, Busker;
3,808,096, Busker e~ al, 3,840,42~, Busker et al; 3,853,698, Mohr; and 4,201,624, Mohr. The devices and method discussed by ~hese previous patents have taken advantage of the knowledge that ~he static applica~ion of mechanical pressure to a wet paper mat can reduce the moisture content in the mat to below 40%. Under the dynamic ~hort-term mechanical pressing which occurs i~ thle usual paper machine where the web i5 run between a ser:Le~ of nips formed between pregs roll ~ouples, it ~s often difficult ~o maintain moisture levels below 60%. Attemp~s to obtain increased dryness in the conventio~al roll-couples are usually made by increasing the press nip pressure, but a ~ 7i~
plateau i5 ~oon reached w~ere m~or increaRe~ ~n roll loading result in rela~ively ~mall decrease~ in mol~ture.
~ known, lt ~s far more efficient to remove water i:n the press 6ec~iGn of ~ paper machin2 than ln the thermal dryer ~ec~ion snd significant reduction i~ energy costs and ~gnifican~ reduction in the ~;pace needed or the dryer drum sectlon of the machine are achieved for every fraction of a percent o$ moisture thst can ~e additionally removed in the press section. The difficulty of removing moisture in ~he prees ~ection is increased with increase in machine speed be-cause limiting factors are reached in press nip pressures in that compacting and crushin~ of the web result~ with higher nip pressures and resultant hi~her hydraulic pressures within the paper mat. The most feasible way th~t has been discovered to :increase water removal at high ~peeds has been to increase the residence or pressure time to allow more time for flow to occur within the paper mat and for the hydraulic pressure to dissipate and for water to be pressed out of the web into the felt.
THF, INVENTION
It is an object of the pre~ent invention to utilize the principles of extended nip pressing increasing the time that a web is subjected to pressing presstlre and to provide an improved mechanism utilizing opposed shoes i~ a 6tructure which accommo-dates relatively hlgh speed travel of a paper web and the appli-cation o ~ pressing ~orce which i8 controlled to optimum nip pressure for the type of paper being ~anufactured.
A further ob~ect of the invention ie to provide an im-proved extended nip press of a relatively ~nccmplicated struc~
ture wh~ch i8 capable o continued operation over a long period of time without requiring servicing or adjustment or signifi-cant attention that would require stopping the machine.
A further obJect of th,e invention 16 to provide an im-pro~ed ex~ended n~p press ~hilch has features of being able to obtain uniform presslng pressure across the width of the travel-ing web for more uniform water removal.
A still further object of the invention is to provide an improved method and structure for an extended nip press which improves the quali~y of the sheet, improves moisture removal, performs a better pressing opera~ion and reduces rewetting.
A further object of the invention is to provide an im-proved press nip which employs an extended nip principle and has an improved structure for driving impervious belts which sandwich the web and felts in the nlp.
A eature of the invention provides opposed shoes which define a press nip between them with impervious belts sandwich-ing the web and felts passing through the nip~ and the shoes having hydraulic films of lubricant and being supported with at least one of the shoes being pivotally mounted so th~t they assume a hydraulically balanced position accommodating the hydraulic pressure nf the film of lubricant which is carried be-tween the shoe and the belt. Pressing forc~ is applied to the nip by a piston and cylinder arrangement supplied with a hy~
draulic fluid so that the hydraulic fluid acts not only to supply the pressing force, but also insures that this pressing force will be absolutely uniform across the entire width of the press nip. The opposed shoes are ~u~ficiently flexible so that they csn bend along their length without introducing forces due to t~eir bending that increase or decrease nip pressure along the shoe length and with the application oE nip pressure solely 78;~
~hrough hydraulic flui~ completQly uniform pressure along ~he full length of the nip can be ~ttained.
~ ther ob~ects, adv~ntages and features, aæ well as equivalent ~tructures and methods which are intended to be covered herein, will become more apparent with the teachin~ of the principles of the invention in connection with the dis-closure of the preferred embodiments thereof in the specifica-tion, c~aims and drawings, in which:
~RAWINGS
The single Figure of the drawings, label~ed FIGURE 1 is ~ somewhat schematic slde elevational view of a press section of a papermaking machine embodying the structure and principles of the present invention.
DESCRIPTION
A nip N for pressing and dew~tering a web is formed be-tween first and second shoes 10 and 11. The shoes ha~e a relieved leading edge shown at 12 and 13 leading to a pressing face 14 and 15. The pressing faces each face the extended nip and are smooth and essentially straight so that they apply a 20 pressing pressure to the web W dur~ng the ~ime it is passing through the nip. As will be recognized by those versed in the art, the shoes extend laterally across the web for slightly lonEJer than the web width, ~nd can be referred to as being elon-gate ln the direction transverse of ~he web travel as indicated by the directional arrow on the web.
The web i~ ~andwiched between felts 18 and 19 which pro-vide means for receiving water pressed from the web, and the felts and web are carried through the nip sandwiched between looped endless lmpervious belts 16 and 17. The web is guided lnto the nip and guided away from the nip by suitable guide 71~
m~mbers, not ~own, and the felt~ are similarly guided into and out of the nip by T0~8 ~uch as 18a ~nd ~b for the upper felt 18, and rolls l9a and 19b ~or the lower felt lg.
The looped belts 16 and 17 a~e ~ade of extremely strong reinforced rubber or similar material, and are driven at the speed of tr~vel of the web so that they cArry th~ web and f~lts through the nip, a~d ~he belt~ are tensioned on guide rolls ~hown for the bel~ 16 at 16a, 16b 9 16c and 16d. Roll 16c may be a tension roll movable in the direction of the arrowed lines 10 by suitable tensioning mechanism, The lower belt 17 is guided by similar tensioning rolls 17a, 17b, 1 7c and 17d, and suitable mechanism is provided for the tension roll 17c ~o move it in the direction of the arrowed linesfor maintaining the desired ten-sion in the belt 17.
An important feature for proper treatment of the web is the means of driving the belts, each of which is wrapped over a grooved traction and guide rolls 20 and 22 for the belts 16 and 17 respectively. The belt is wrapped over these rolls for an arc preferably in excess of 90, and it has been found that an improved tracking and driving relation~hip is attained by providing uniform circumerential grooves in the 6urface of the roll with the grooves shown schematically by the broken lines 21 and 23 for the rolls 20 and 22 respectively. These grooves are annular recesses cut a~ uniform intervals along the surface oE the roll leaving flat land areas therebetween. These grooves apparently permit the ~cape of any moisture which may be en-trapped between the belt and rol1, and permit the belt to de-pre~s slightly into th~ grooves,due to its being tensioned to thereby increase the traction between the belt and rolls and ~1BO increase the uniformity oE drive and guiding ~elationship.
`
Uniform treatment af the belt~ i8 necessary 8~ that the web and felts can be dragged uniformly hrough the ~lp.
The grooved traotion rolls 20 and 22 e~gage the outer ~urf2~e of the belt, which Ls the surface ~ha~ i~ ad;acent the felts in the nip. Thus, no driving or traction forces are applied to the inner ~urace of the belts which surfaces slide over the shoes 10 and 11. Any abrasion caused by the drive is not directed at the ~liding surface of the belt. Further, lt i~ to ~e noted that it is the outer surface of the belt which ]- will be wet from i~s con~act with the fel~ so that this wetness on the belt surface has be~n found to be accommodated by the unique grooved traction rolls 20 and 22.
A film of lubricating fluid i5 co~tinuously developed between the flat surfaces 14 and 15 of the shoes and the belts due to the fact that their leading edges 12 and 13 are relieved and a continuous supply of lubricant is delivered at the loca-tion of these relieved edges by jets 24 and 25. The lubricant may be of various substances, such as oil, and is applied in a manner so that each of the shoes acts as a slipper bearing and actually while the shoes press toward each other, the film of lubricating liquid is continuous so that there is a hydraulic transmission o the force of the shoe to the bel~ through the lubricant. This, of course, reduces the friction between the belt and the shoe, but also provides for a more improved press-ing action in that pressure uniformity is enhanced due to ~he fact that there is a body of l~quid between the face of ~he shoe and lthe belt, and the liquid must adopt uniform pressure along the elongate length of the shoe.
Because of the hydraulic reac~ivn against the shoe due to the lubricsnt layer between the shoe and bel~, the shoes 8~
will tend to tlle to a neutral position. That i6, the 6hoes ~re e2ch ~hown as mounted on a central pivot 27 and 29. These pivot6 are ~ocate~ approxi~ate~y midway between the front and back edges of the 6hoe, ~nd the ~hoes will operate at a balanced position wherein the hydraulic $orces o the lubricant ahead of the pivot are the same as the hydraulic forces behind the pivot.
Edge seal~ m~y be p~o~ided at the edges of the belt to prevent lubricant from migrating around the edge of the belt, but experience has shown that the amount of lubricant passing around the edge of the belt is minimal so that edge seals are not absolutely essential. The trailing edge of the ~hoes are rounded slightly at lOa and lla ~o reduce the concantration of pressure against the belt as the bel~s emerge from the ~railing edges of the shoes. While each shoe is pivotally mounted by a pivot pin which extends laterally across ~he entire wldth of the machine so that the shoe i6 pivotally supported about its lateral axis, in some instances, it may be desired to pivotally mount only one of the shoes. Thi~ will still achieve ehe hy-draulic balance in the nip inasmuch s the one pivo~ed shoe will pivot to a neutral position with hydraulic orces ahead of and behind the pivot being uniform.
The shoes are supporeed on opposed heavy beams 26 and 28 above and below the shoes 10 ~nd 11. As referred to above, ehe pivot pin 27 may be omitted in some instances, and the shoe 10 mounted rigiclly on the beam 26, and only the pivot pin 29 pro-vided. This iB an alternate struceure~ but the pivotal support for each of t:he shoes i9 preferred. The pivoe pins can be so located relat:ive to the leading and trailing edge of the ~hoe so that uniform pressure occurs throughout the lengeh of the extended nip or may be set ~lightly downstream in the direction of the web movement 50 that a slightly lower ~nit nip pressure oceurs ahPad of the pin than ~Ifter the pivot pin. The shoes will ass~me a position of bal~mce wherein the tot~l hydraulic ~orces of the lubricant in the nlp ahead of ehe pivot pin equal those behind the pivot pin.
For applying the presslure to the shoes to attain the press-ing force in the nip, the lower shoe is mounted on a piston 30 seated in a cylinder 31. Hydraulic liquid is deliv~red to the pi ton beneath the cylinder by suitable means indicated by the llne 32. The cylinder or channel 31 beneath the piston is preferably continuous, or if separated, the same pressure is applied to each of the chambers 80 that the upward force on the shc,e is uniform throughout its length across the machine. If the cylinder or chamber 31 ~s continuous, since the hydraulic fluid will be at the same pressure throughout the continuous cyl.inder 31, a uniform upward force will be appliPd to the shoe throughout its length insuring $hat ~he pressing force in the nip will be uniform across ~he machine. Wi~h high nip pressures, the upper beam 26 may bow upwardly slightly in its middle, but the ~hoes 10 and 11 are sufficiently limber B0 that they will bow wlth tha beam without introducing any significant forces due to their rasi~tance to bending, and thus the uniform pressure ln ~he nip will not be altered. Similarly, the piston will bow slightly to conform to the bending of the upper beam 2$, but the amount of ~urvature due to ~his bowing will be ~nsigniicant and will not affect the uniforml~y of pressure in the nip across the machlne. If the lower beam 2~ bows downwardly, this shape will not be transmitted to the shoes because the sole upward force on t:he piston is derived rom ~he ~orce of the hydraulic liquid in the cylinder 31 beneath t:he piston.
In some instances, lt may be dei~irable to support the upper shoe on a piston and cyli.nder arrangement similar to the piston and cylinder 30 and 31 so that a force is applied bo~h to the upper shoe and to the lower shoe. Or, of course; it will be under~tood that the lower shoe may be supported directly on a beam Oll a pivot pin without a piston and cylinder, and the piston and cylinder be provided for the upper beam and upper shoe. If a single piston and cylinder is u9ed, it is preferred that it be used on the lower beam 28, because the weight of the upper beam ~6 tends to counteract the upward reaction orce from the shoe 10 applying pressure to the nip.
In operation the two belts 16 and 17 are driven at the speed of travel of the web due to their frictional tracking en-gagement with their driving rolls 20 and 22. The felts 18 and 19 are carried through the nip with the web between them, and as water is pressed from the web from the time it enters the nip N at the leading edge of the shoes 10 and 11 to where it leaves the shoes, it is received by the felts which are dried in ~he usual manner. Control of the pressure in the nip i8 obtained by the pressure of the hydraulic fluid delivered through ~he line 32 to the cylinder chamber 31. 'rhe shoe3 can be held in loose en~agement witn the belts at start-up and pressure increased as the machine reaches operating speed, and the pressure adj-lsted in accordance with the dei~ired operat~on and the amoun~ of wa~er to be pressed from the web in the ex-tended nip.
'rhe drlving rolls drive the belts at uniform speed n~tin-taining constant and uniform traction despite any water which remains on the surface of the belts. It i8 to be understood t,hat the advantages o~ the l~lique driving rolls may be employed in other orms o:E extended nip presses, ~uch a~, for example, structures such as ~hown in Re 30, 268 by forcin~ a grooved driving roll ~nto driving contact wlth ~he ou'cer iQurface of the bel~ .
Other forms ~f ~tructures and modifications of the method alling within the spirit and acope of the invention are in-tended to be covered herein, and applicant is not limited by the specific preferred embodiment of ~tructure illustrated.
~3~
The inventlon relate~ to ~n improved method and mechan-ism ~or pressing wa~e~ rom ~ ~ravelin~ paper web, and more particularly to ~ pre~ arrangement know~ a~ an extended press nip wherein the web i6 sub3ect:ed to presslng pressures for a longer period of ~i~R than the usual arr~ngement wherein it pa~ses between two opposed pres~ roll&.
More par~icularly, the invention relates to a method and structure having a press nip wherein the residence time of the web in the nips iæ increased over tha~ of a roll couple and wherein an impro~ed structure is used to extract watPr from a web. Other structures have been provided heretofore which have attempted to increase the time over which a web is subjected to a pressure, and yet permit the web to continuP
movement at a speed necessary in a high ~peed papermaking machine. Such struc~ures have met with degrees of success and are exempli~ied by the disclosure~ of U.S. Pat. Nos. 3,748,225, Busker et al; 3,783,097, (Re. 30,268), Ju~tus; 3,797,384, Hoff, 3, 798, 121, Busker et al; 3, 804, 707, Mohr; 3, 808, 092, Busker;
3,808,096, Busker e~ al, 3,840,42~, Busker et al; 3,853,698, Mohr; and 4,201,624, Mohr. The devices and method discussed by ~hese previous patents have taken advantage of the knowledge that ~he static applica~ion of mechanical pressure to a wet paper mat can reduce the moisture content in the mat to below 40%. Under the dynamic ~hort-term mechanical pressing which occurs i~ thle usual paper machine where the web i5 run between a ser:Le~ of nips formed between pregs roll ~ouples, it ~s often difficult ~o maintain moisture levels below 60%. Attemp~s to obtain increased dryness in the conventio~al roll-couples are usually made by increasing the press nip pressure, but a ~ 7i~
plateau i5 ~oon reached w~ere m~or increaRe~ ~n roll loading result in rela~ively ~mall decrease~ in mol~ture.
~ known, lt ~s far more efficient to remove water i:n the press 6ec~iGn of ~ paper machin2 than ln the thermal dryer ~ec~ion snd significant reduction i~ energy costs and ~gnifican~ reduction in the ~;pace needed or the dryer drum sectlon of the machine are achieved for every fraction of a percent o$ moisture thst can ~e additionally removed in the press section. The difficulty of removing moisture in ~he prees ~ection is increased with increase in machine speed be-cause limiting factors are reached in press nip pressures in that compacting and crushin~ of the web result~ with higher nip pressures and resultant hi~her hydraulic pressures within the paper mat. The most feasible way th~t has been discovered to :increase water removal at high ~peeds has been to increase the residence or pressure time to allow more time for flow to occur within the paper mat and for the hydraulic pressure to dissipate and for water to be pressed out of the web into the felt.
THF, INVENTION
It is an object of the pre~ent invention to utilize the principles of extended nip pressing increasing the time that a web is subjected to pressing presstlre and to provide an improved mechanism utilizing opposed shoes i~ a 6tructure which accommo-dates relatively hlgh speed travel of a paper web and the appli-cation o ~ pressing ~orce which i8 controlled to optimum nip pressure for the type of paper being ~anufactured.
A further ob~ect of the invention ie to provide an im-proved extended nip press of a relatively ~nccmplicated struc~
ture wh~ch i8 capable o continued operation over a long period of time without requiring servicing or adjustment or signifi-cant attention that would require stopping the machine.
A further obJect of th,e invention 16 to provide an im-pro~ed ex~ended n~p press ~hilch has features of being able to obtain uniform presslng pressure across the width of the travel-ing web for more uniform water removal.
A still further object of the invention is to provide an improved method and structure for an extended nip press which improves the quali~y of the sheet, improves moisture removal, performs a better pressing opera~ion and reduces rewetting.
A further object of the invention is to provide an im-proved press nip which employs an extended nip principle and has an improved structure for driving impervious belts which sandwich the web and felts in the nlp.
A eature of the invention provides opposed shoes which define a press nip between them with impervious belts sandwich-ing the web and felts passing through the nip~ and the shoes having hydraulic films of lubricant and being supported with at least one of the shoes being pivotally mounted so th~t they assume a hydraulically balanced position accommodating the hydraulic pressure nf the film of lubricant which is carried be-tween the shoe and the belt. Pressing forc~ is applied to the nip by a piston and cylinder arrangement supplied with a hy~
draulic fluid so that the hydraulic fluid acts not only to supply the pressing force, but also insures that this pressing force will be absolutely uniform across the entire width of the press nip. The opposed shoes are ~u~ficiently flexible so that they csn bend along their length without introducing forces due to t~eir bending that increase or decrease nip pressure along the shoe length and with the application oE nip pressure solely 78;~
~hrough hydraulic flui~ completQly uniform pressure along ~he full length of the nip can be ~ttained.
~ ther ob~ects, adv~ntages and features, aæ well as equivalent ~tructures and methods which are intended to be covered herein, will become more apparent with the teachin~ of the principles of the invention in connection with the dis-closure of the preferred embodiments thereof in the specifica-tion, c~aims and drawings, in which:
~RAWINGS
The single Figure of the drawings, label~ed FIGURE 1 is ~ somewhat schematic slde elevational view of a press section of a papermaking machine embodying the structure and principles of the present invention.
DESCRIPTION
A nip N for pressing and dew~tering a web is formed be-tween first and second shoes 10 and 11. The shoes ha~e a relieved leading edge shown at 12 and 13 leading to a pressing face 14 and 15. The pressing faces each face the extended nip and are smooth and essentially straight so that they apply a 20 pressing pressure to the web W dur~ng the ~ime it is passing through the nip. As will be recognized by those versed in the art, the shoes extend laterally across the web for slightly lonEJer than the web width, ~nd can be referred to as being elon-gate ln the direction transverse of ~he web travel as indicated by the directional arrow on the web.
The web i~ ~andwiched between felts 18 and 19 which pro-vide means for receiving water pressed from the web, and the felts and web are carried through the nip sandwiched between looped endless lmpervious belts 16 and 17. The web is guided lnto the nip and guided away from the nip by suitable guide 71~
m~mbers, not ~own, and the felt~ are similarly guided into and out of the nip by T0~8 ~uch as 18a ~nd ~b for the upper felt 18, and rolls l9a and 19b ~or the lower felt lg.
The looped belts 16 and 17 a~e ~ade of extremely strong reinforced rubber or similar material, and are driven at the speed of tr~vel of the web so that they cArry th~ web and f~lts through the nip, a~d ~he belt~ are tensioned on guide rolls ~hown for the bel~ 16 at 16a, 16b 9 16c and 16d. Roll 16c may be a tension roll movable in the direction of the arrowed lines 10 by suitable tensioning mechanism, The lower belt 17 is guided by similar tensioning rolls 17a, 17b, 1 7c and 17d, and suitable mechanism is provided for the tension roll 17c ~o move it in the direction of the arrowed linesfor maintaining the desired ten-sion in the belt 17.
An important feature for proper treatment of the web is the means of driving the belts, each of which is wrapped over a grooved traction and guide rolls 20 and 22 for the belts 16 and 17 respectively. The belt is wrapped over these rolls for an arc preferably in excess of 90, and it has been found that an improved tracking and driving relation~hip is attained by providing uniform circumerential grooves in the 6urface of the roll with the grooves shown schematically by the broken lines 21 and 23 for the rolls 20 and 22 respectively. These grooves are annular recesses cut a~ uniform intervals along the surface oE the roll leaving flat land areas therebetween. These grooves apparently permit the ~cape of any moisture which may be en-trapped between the belt and rol1, and permit the belt to de-pre~s slightly into th~ grooves,due to its being tensioned to thereby increase the traction between the belt and rolls and ~1BO increase the uniformity oE drive and guiding ~elationship.
`
Uniform treatment af the belt~ i8 necessary 8~ that the web and felts can be dragged uniformly hrough the ~lp.
The grooved traotion rolls 20 and 22 e~gage the outer ~urf2~e of the belt, which Ls the surface ~ha~ i~ ad;acent the felts in the nip. Thus, no driving or traction forces are applied to the inner ~urace of the belts which surfaces slide over the shoes 10 and 11. Any abrasion caused by the drive is not directed at the ~liding surface of the belt. Further, lt i~ to ~e noted that it is the outer surface of the belt which ]- will be wet from i~s con~act with the fel~ so that this wetness on the belt surface has be~n found to be accommodated by the unique grooved traction rolls 20 and 22.
A film of lubricating fluid i5 co~tinuously developed between the flat surfaces 14 and 15 of the shoes and the belts due to the fact that their leading edges 12 and 13 are relieved and a continuous supply of lubricant is delivered at the loca-tion of these relieved edges by jets 24 and 25. The lubricant may be of various substances, such as oil, and is applied in a manner so that each of the shoes acts as a slipper bearing and actually while the shoes press toward each other, the film of lubricating liquid is continuous so that there is a hydraulic transmission o the force of the shoe to the bel~ through the lubricant. This, of course, reduces the friction between the belt and the shoe, but also provides for a more improved press-ing action in that pressure uniformity is enhanced due to ~he fact that there is a body of l~quid between the face of ~he shoe and lthe belt, and the liquid must adopt uniform pressure along the elongate length of the shoe.
Because of the hydraulic reac~ivn against the shoe due to the lubricsnt layer between the shoe and bel~, the shoes 8~
will tend to tlle to a neutral position. That i6, the 6hoes ~re e2ch ~hown as mounted on a central pivot 27 and 29. These pivot6 are ~ocate~ approxi~ate~y midway between the front and back edges of the 6hoe, ~nd the ~hoes will operate at a balanced position wherein the hydraulic $orces o the lubricant ahead of the pivot are the same as the hydraulic forces behind the pivot.
Edge seal~ m~y be p~o~ided at the edges of the belt to prevent lubricant from migrating around the edge of the belt, but experience has shown that the amount of lubricant passing around the edge of the belt is minimal so that edge seals are not absolutely essential. The trailing edge of the ~hoes are rounded slightly at lOa and lla ~o reduce the concantration of pressure against the belt as the bel~s emerge from the ~railing edges of the shoes. While each shoe is pivotally mounted by a pivot pin which extends laterally across ~he entire wldth of the machine so that the shoe i6 pivotally supported about its lateral axis, in some instances, it may be desired to pivotally mount only one of the shoes. Thi~ will still achieve ehe hy-draulic balance in the nip inasmuch s the one pivo~ed shoe will pivot to a neutral position with hydraulic orces ahead of and behind the pivot being uniform.
The shoes are supporeed on opposed heavy beams 26 and 28 above and below the shoes 10 ~nd 11. As referred to above, ehe pivot pin 27 may be omitted in some instances, and the shoe 10 mounted rigiclly on the beam 26, and only the pivot pin 29 pro-vided. This iB an alternate struceure~ but the pivotal support for each of t:he shoes i9 preferred. The pivoe pins can be so located relat:ive to the leading and trailing edge of the ~hoe so that uniform pressure occurs throughout the lengeh of the extended nip or may be set ~lightly downstream in the direction of the web movement 50 that a slightly lower ~nit nip pressure oceurs ahPad of the pin than ~Ifter the pivot pin. The shoes will ass~me a position of bal~mce wherein the tot~l hydraulic ~orces of the lubricant in the nlp ahead of ehe pivot pin equal those behind the pivot pin.
For applying the presslure to the shoes to attain the press-ing force in the nip, the lower shoe is mounted on a piston 30 seated in a cylinder 31. Hydraulic liquid is deliv~red to the pi ton beneath the cylinder by suitable means indicated by the llne 32. The cylinder or channel 31 beneath the piston is preferably continuous, or if separated, the same pressure is applied to each of the chambers 80 that the upward force on the shc,e is uniform throughout its length across the machine. If the cylinder or chamber 31 ~s continuous, since the hydraulic fluid will be at the same pressure throughout the continuous cyl.inder 31, a uniform upward force will be appliPd to the shoe throughout its length insuring $hat ~he pressing force in the nip will be uniform across ~he machine. Wi~h high nip pressures, the upper beam 26 may bow upwardly slightly in its middle, but the ~hoes 10 and 11 are sufficiently limber B0 that they will bow wlth tha beam without introducing any significant forces due to their rasi~tance to bending, and thus the uniform pressure ln ~he nip will not be altered. Similarly, the piston will bow slightly to conform to the bending of the upper beam 2$, but the amount of ~urvature due to ~his bowing will be ~nsigniicant and will not affect the uniforml~y of pressure in the nip across the machlne. If the lower beam 2~ bows downwardly, this shape will not be transmitted to the shoes because the sole upward force on t:he piston is derived rom ~he ~orce of the hydraulic liquid in the cylinder 31 beneath t:he piston.
In some instances, lt may be dei~irable to support the upper shoe on a piston and cyli.nder arrangement similar to the piston and cylinder 30 and 31 so that a force is applied bo~h to the upper shoe and to the lower shoe. Or, of course; it will be under~tood that the lower shoe may be supported directly on a beam Oll a pivot pin without a piston and cylinder, and the piston and cylinder be provided for the upper beam and upper shoe. If a single piston and cylinder is u9ed, it is preferred that it be used on the lower beam 28, because the weight of the upper beam ~6 tends to counteract the upward reaction orce from the shoe 10 applying pressure to the nip.
In operation the two belts 16 and 17 are driven at the speed of travel of the web due to their frictional tracking en-gagement with their driving rolls 20 and 22. The felts 18 and 19 are carried through the nip with the web between them, and as water is pressed from the web from the time it enters the nip N at the leading edge of the shoes 10 and 11 to where it leaves the shoes, it is received by the felts which are dried in ~he usual manner. Control of the pressure in the nip i8 obtained by the pressure of the hydraulic fluid delivered through ~he line 32 to the cylinder chamber 31. 'rhe shoe3 can be held in loose en~agement witn the belts at start-up and pressure increased as the machine reaches operating speed, and the pressure adj-lsted in accordance with the dei~ired operat~on and the amoun~ of wa~er to be pressed from the web in the ex-tended nip.
'rhe drlving rolls drive the belts at uniform speed n~tin-taining constant and uniform traction despite any water which remains on the surface of the belts. It i8 to be understood t,hat the advantages o~ the l~lique driving rolls may be employed in other orms o:E extended nip presses, ~uch a~, for example, structures such as ~hown in Re 30, 268 by forcin~ a grooved driving roll ~nto driving contact wlth ~he ou'cer iQurface of the bel~ .
Other forms ~f ~tructures and modifications of the method alling within the spirit and acope of the invention are in-tended to be covered herein, and applicant is not limited by the specific preferred embodiment of ~tructure illustrated.
Claims (7)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A press mechanism for removing water from a travel ing fibrous web comprising in combination:
an elongate extended press nip formed between a first pressing shoe at one side of the nip having a relieved leading edge with a following elongate pressing face at one side of the press nip; and a second pressing shoe at the other side of the press nip having a relieved leading front edge with a following elongate pressing face at the other side of the press nip, said elongate pressing faces on either side of the press nip being in opposed array and substantially congruent;
means in the nip for receiving water pressed from the web;
first and second traveling belts passing through the nip between the shoes with said web and water receiving means sandwiched therebetween;
means for delivering lubricant to the leading edge of each of the shoes to develop a hydraulic wedge of lubricant between each of the shoes and the respective belts traveling through the nip;
support means for each of the pressing shoes which includes means for allowing movement of the shoes responsive to the hydrodynamic forces created by the traveling lubricant on the first and second belts whereby the extended nip is defined on the elongate pressing faces; and means for applying a pressing force to at least one of the shoes urging it toward the nip for applying dewatering pressing force to the web in the nip.
an elongate extended press nip formed between a first pressing shoe at one side of the nip having a relieved leading edge with a following elongate pressing face at one side of the press nip; and a second pressing shoe at the other side of the press nip having a relieved leading front edge with a following elongate pressing face at the other side of the press nip, said elongate pressing faces on either side of the press nip being in opposed array and substantially congruent;
means in the nip for receiving water pressed from the web;
first and second traveling belts passing through the nip between the shoes with said web and water receiving means sandwiched therebetween;
means for delivering lubricant to the leading edge of each of the shoes to develop a hydraulic wedge of lubricant between each of the shoes and the respective belts traveling through the nip;
support means for each of the pressing shoes which includes means for allowing movement of the shoes responsive to the hydrodynamic forces created by the traveling lubricant on the first and second belts whereby the extended nip is defined on the elongate pressing faces; and means for applying a pressing force to at least one of the shoes urging it toward the nip for applying dewatering pressing force to the web in the nip.
2. A press mechanism for removing water from a traveling fibrous web constructed in accordance with claim 1:
wherein the support means includes a pivotal support for at least one of the shoes permitting it to pivot about an axis transverse of the direction of web travel so that the shoe will assume a hydraulically balanced position relative to the lubricant delivered to the leading edge and situated between the belt and shoe.
wherein the support means includes a pivotal support for at least one of the shoes permitting it to pivot about an axis transverse of the direction of web travel so that the shoe will assume a hydraulically balanced position relative to the lubricant delivered to the leading edge and situated between the belt and shoe.
3. A press mechanism for removing water from a traveling fibrous web constructed in accordance with claim 1:
and including first and second pivotal support respect-ively for said first and second shoes permitting pivotal movement about an axis transverse of the direction of web travel so that the shoes assume a hydraulically balanced position relative to the forces applied to the faces of the shoe by the lubricant between the shoes and their respective belts.
and including first and second pivotal support respect-ively for said first and second shoes permitting pivotal movement about an axis transverse of the direction of web travel so that the shoes assume a hydraulically balanced position relative to the forces applied to the faces of the shoe by the lubricant between the shoes and their respective belts.
4. A press mechanism for removing water from a traveling fibrous web constructed in accordance with claim 1:
wherein said means for applying the pressing force includes a transversely extending fluid support for one of said shoes applying a force to the shoe which is uniform along the length of the shoe transverse of the direction of web travel so that a uniform force is applied to the web along the nip.
wherein said means for applying the pressing force includes a transversely extending fluid support for one of said shoes applying a force to the shoe which is uniform along the length of the shoe transverse of the direction of web travel so that a uniform force is applied to the web along the nip.
5. A press mechanism for removing water from a traveling fibrous web constructed in accordance with claim 4:
wherein the fluid support is in the form of a piston and cylinder with the cylinder carried on a relatively rigid support and the piston is supported in the cylinder by pressurized liquid and the cylinder supporting the shoe on a pivot extending transversely of the direction of web travel.
wherein the fluid support is in the form of a piston and cylinder with the cylinder carried on a relatively rigid support and the piston is supported in the cylinder by pressurized liquid and the cylinder supporting the shoe on a pivot extending transversely of the direction of web travel.
6. A press mechanism for removing water from a traveling fibrous web constructed in accordance with claim 1:
wherein the water receiving means is in the form of first and second felts positioned adjacent the traveling belts with the web sandwiched between said felts.
wherein the water receiving means is in the form of first and second felts positioned adjacent the traveling belts with the web sandwiched between said felts.
7. A press mechanism for removing water from a traveling fibrous web comprising in combination:
an elongate extended press nip formed between a first pressing shoe at one side of the nip having a relieved front leading edge with a following elongate pressing face at one side of the press nip; and a second pressing shoe at the other side of the nip having a relieved leading front edge with a following elongate pressing face at the other side of the press nip;
means guiding a traveling web through said nip for pressing and dewatering the web;
first and second felts sandwiching the web therebetween and passing through the nip;
first and second traveling looped belts passing through the nip between the shoes with the web and felts sandwiched therebetween;
means for delivering lubricant to the leading edge of each of the shoes to develop a hydraulic wedge of lubricant between the shoes and their respective belts;
guide and tension rolls for each of the belts including a traction drive roll having annular grooves therein with the belts wrapped over the traction roll in driven relationship thereto;
pivotal supports for each of the shoes supporting the shoes for pivotal movement about an axis transverse to the direction of web movement;
a relatively rigid support beam means supporting the first shoe on its pivotal support;
a relatively rigid second support beam means for the second shoe;
a cylinder in the second beam with an elongate piston means in the cylinder with the cylinder and piston extending transversely along the shoe and supporting the shoe pivotally on the piston; and means for delivering a pressurized fluid to the cylinder for applying a pressing force to the second shoe and providing a pressing force to the web in the nip uniformly across the length of the nip.
an elongate extended press nip formed between a first pressing shoe at one side of the nip having a relieved front leading edge with a following elongate pressing face at one side of the press nip; and a second pressing shoe at the other side of the nip having a relieved leading front edge with a following elongate pressing face at the other side of the press nip;
means guiding a traveling web through said nip for pressing and dewatering the web;
first and second felts sandwiching the web therebetween and passing through the nip;
first and second traveling looped belts passing through the nip between the shoes with the web and felts sandwiched therebetween;
means for delivering lubricant to the leading edge of each of the shoes to develop a hydraulic wedge of lubricant between the shoes and their respective belts;
guide and tension rolls for each of the belts including a traction drive roll having annular grooves therein with the belts wrapped over the traction roll in driven relationship thereto;
pivotal supports for each of the shoes supporting the shoes for pivotal movement about an axis transverse to the direction of web movement;
a relatively rigid support beam means supporting the first shoe on its pivotal support;
a relatively rigid second support beam means for the second shoe;
a cylinder in the second beam with an elongate piston means in the cylinder with the cylinder and piston extending transversely along the shoe and supporting the shoe pivotally on the piston; and means for delivering a pressurized fluid to the cylinder for applying a pressing force to the second shoe and providing a pressing force to the web in the nip uniformly across the length of the nip.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US25893281A | 1981-04-30 | 1981-04-30 | |
| US258,932 | 1981-04-30 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1181975A true CA1181975A (en) | 1985-02-05 |
Family
ID=22982744
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000398006A Expired CA1181975A (en) | 1981-04-30 | 1982-03-10 | Extended nip press |
Country Status (10)
| Country | Link |
|---|---|
| EP (1) | EP0064933B1 (en) |
| JP (1) | JPS5930836B2 (en) |
| KR (1) | KR860001618B1 (en) |
| AR (1) | AR226644A1 (en) |
| BR (1) | BR8202582A (en) |
| CA (1) | CA1181975A (en) |
| DE (1) | DE3273815D1 (en) |
| ES (1) | ES8304243A1 (en) |
| FI (1) | FI820642L (en) |
| IN (1) | IN156378B (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI87376C (en) * | 1986-02-12 | 1993-07-20 | Valmet Oy | An essentially hydrostatic slip shoe |
| JPH0194240U (en) * | 1987-12-16 | 1989-06-21 | ||
| DE29622025U1 (en) * | 1996-10-16 | 1997-03-27 | Voith Sulzer Papiermaschinen GmbH, 89522 Heidenheim | Pressing device |
| DE19644108A1 (en) * | 1996-10-31 | 1998-05-07 | Voith Sulzer Papiermasch Gmbh | Shoe press |
| DE19723172A1 (en) * | 1997-06-03 | 1998-12-10 | Geldmacher Joachim | Fibre web press assembly, enabling additional water extraction from e.g. paper web |
| EP1205600A1 (en) * | 2000-11-03 | 2002-05-15 | Voith Paper Patent GmbH | Shoe press |
| DE10054674A1 (en) * | 2000-11-03 | 2002-05-08 | Voith Paper Patent Gmbh | Shoe press treating paper web includes driven, continuous pressing bands on either side of web, led with it through felted pressing nip |
| DE10132652A1 (en) * | 2001-07-05 | 2003-01-16 | Voith Paper Patent Gmbh | Press assembly, for wet lightweight paper/cardboard webs, has a single shoe press with an extended press nip and continuous blankets flanking the web with a drive for at least one blanket |
| US8178045B2 (en) | 2007-12-17 | 2012-05-15 | University Of Louisville Research Foundation, Inc. | Interchangeable preconcentrator connector assembly |
| US8448532B2 (en) | 2009-03-18 | 2013-05-28 | The United States Of America As Represented By The Secretary Of The Navy | Actively cooled vapor preconcentrator |
| CN115679743A (en) * | 2021-07-23 | 2023-02-03 | 欧佩德伺服电机节能系统有限公司 | Press device for processing paper web |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US38092A (en) * | 1863-04-07 | Improved stump-pulling machine | ||
| US3748225A (en) * | 1970-11-19 | 1973-07-24 | Beloit Corp | Fibrous web press nip structure including nonporous belts backed by pistons supported with fluid pressure |
| US3783097A (en) * | 1972-05-30 | 1974-01-01 | Beloit Corp | Hydrodynamically loaded web press with slipper bearing shoes |
| US4287021A (en) * | 1979-08-27 | 1981-09-01 | Beloit Corporation | Extended nip press |
-
1982
- 1982-02-25 FI FI820642A patent/FI820642L/en not_active Application Discontinuation
- 1982-03-10 CA CA000398006A patent/CA1181975A/en not_active Expired
- 1982-04-16 JP JP57062639A patent/JPS5930836B2/en not_active Expired
- 1982-04-17 IN IN429/CAL/82A patent/IN156378B/en unknown
- 1982-04-27 AR AR289223A patent/AR226644A1/en active
- 1982-04-29 ES ES511807A patent/ES8304243A1/en not_active Expired
- 1982-04-30 EP EP82630035A patent/EP0064933B1/en not_active Expired
- 1982-04-30 KR KR8201918A patent/KR860001618B1/en not_active Expired
- 1982-04-30 BR BR8202582A patent/BR8202582A/en unknown
- 1982-04-30 DE DE8282630035T patent/DE3273815D1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| AR226644A1 (en) | 1982-07-30 |
| ES511807A0 (en) | 1983-03-01 |
| KR860001618B1 (en) | 1986-10-14 |
| KR830010247A (en) | 1983-12-30 |
| DE3273815D1 (en) | 1986-11-20 |
| FI820642A7 (en) | 1982-10-31 |
| FI820642L (en) | 1982-10-31 |
| EP0064933A1 (en) | 1982-11-17 |
| EP0064933B1 (en) | 1986-10-15 |
| JPS57183491A (en) | 1982-11-11 |
| IN156378B (en) | 1985-07-06 |
| ES8304243A1 (en) | 1983-03-01 |
| JPS5930836B2 (en) | 1984-07-28 |
| BR8202582A (en) | 1983-04-19 |
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Legal Events
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| MKEC | Expiry (correction) | ||
| MKEX | Expiry |