CA1143982A - Apparatus and method for maintaining the permeability of paper and board machine felts - Google Patents
Apparatus and method for maintaining the permeability of paper and board machine feltsInfo
- Publication number
- CA1143982A CA1143982A CA000358375A CA358375A CA1143982A CA 1143982 A CA1143982 A CA 1143982A CA 000358375 A CA000358375 A CA 000358375A CA 358375 A CA358375 A CA 358375A CA 1143982 A CA1143982 A CA 1143982A
- Authority
- CA
- Canada
- Prior art keywords
- felt
- permeability
- spray
- vacuum
- predetermined value
- 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
- D21F1/32—Washing wire-cloths or felts
Landscapes
- Paper (AREA)
Abstract
ABSTRACT
Apparatus and method for maintaining the permeability of paper and board machine felts A method of maintaining the permeability of felts (1) in paper board and like machines comprises the steps of monitoring the permeability of the felt (1), and bringing into operation apparatus (5) for directing at the felt a spray of liquid for reconditioning the felt (1), when the monitored permeability monitored by means (11) reaches a first predetermined value and terminating the operation of the apparatus when the permeability reaches another second predetermined value higher than the first value.
Apparatus and method for maintaining the permeability of paper and board machine felts A method of maintaining the permeability of felts (1) in paper board and like machines comprises the steps of monitoring the permeability of the felt (1), and bringing into operation apparatus (5) for directing at the felt a spray of liquid for reconditioning the felt (1), when the monitored permeability monitored by means (11) reaches a first predetermined value and terminating the operation of the apparatus when the permeability reaches another second predetermined value higher than the first value.
Description
__tus and metllo~ for maintaininc~ the_E_rmea~ilit~
~C~:3 ~ `L ~ }~ elts ~- ~ - ~~~
This invention relates to apparatus and to meth~s o~ maintaining the permeability of paper and board machine press felts.
Such machines employ press felts to transport the S r~w paper or board and ~o accept water presse~ f-om rhe raw materi.al during the manu~actur~ o~ paper anc' board in ~he press section of machi.rlery for ma~inc~ paper, ~oard alld asbestos/cement sheets and in the so-called ma7;.inc3" section o-f machines ror making ashestos/cel-nent sheets.
All l~ress f:e.l.ts will comp2ct in use to an e~tent related to thcir dcs.ign, compressibility lencJth press loading specd and contamination.
AS they compact the ability of the felt to accept water and to allow water passage through 1~ structure 15 reduc~s and this reduces tne a~ility of the felt to receive cont~minants because the compaction reduces the a~ailable vol~me in the felt ~tween the interstices thereof.
Tnus, the condition of the felt continuously deteri-orates throughout its li~e and its e~ficiency gradually 20 reduces. To o~rercome this the present methocl is to use a high-pressure needle~jet shower, operating at a pressure of say 35 ~g/cm2 "~lose high energy jets of ~later loosen the contaminants and -ebulk the felt~ The hi~h pressure is needed, to be e.~fectiv2, but i-he use of the sho~,ler is usually 25 discontinuous say 30 minutea per shift, or ir operated continuollslv the structure OL the elt ~tould be dama~et~.
1'he currt-~nk 5y5tem incorporates an intermitient hit~h-pressurt-~
!
- . :
;
l32 needle-jet, oscillating shower, to rebulk the felt~ a continuous, low~pressure fan shower to wash out the contaminants, and a Yacuum box to remove contaminated water from the felt.
All felts have their part~cular feltlwater ratio maximums, i.e.
saturation, and minimums, i.e. through Yacuum extraction, and they~operate within those limits, to accept water pressed out of the paper or board sheet.
If the ratio is high then the low pressure fan show.er is often not used because there is enough water to act as a contaminant transport for the vacuum box.
~lowever, the high-pressure, needle jet shower must be incorporated to maintain the bulk and the vacuum ~ox must be incorporated to remoYe the water from the paper.
It is an object of the present invention to ensure that the high pressure shower ;s used effectively to maintain the felt in good condition and so prolong its working life and to ensure efficient water extraction.
According to the invention a method of maintaining the permeability of felts in paper and board machines, comprises the following sequential steps:
(i) monitoring the permeability of the felt, (ii) sensing that the permeability of the felt has fallen to a first ~ ~ .
predetermined value, (iii) in response to sensing that the permeability of the felt has fallen to the first predetermined val-ue, directing at the felt at least one spray jet~
of liquid for reconditioning the felt and moving said at least one spray jet :~
widthwise of the felt in a cyclic movement to spray the entire width of the felt in each cycle, ~iv) sensing that the permeability of the felt has risen to a second predetermined value higher than the first value, (v) continuing to direct at the felt at least one spray jet of liquid for
~C~:3 ~ `L ~ }~ elts ~- ~ - ~~~
This invention relates to apparatus and to meth~s o~ maintaining the permeability of paper and board machine press felts.
Such machines employ press felts to transport the S r~w paper or board and ~o accept water presse~ f-om rhe raw materi.al during the manu~actur~ o~ paper anc' board in ~he press section of machi.rlery for ma~inc~ paper, ~oard alld asbestos/cement sheets and in the so-called ma7;.inc3" section o-f machines ror making ashestos/cel-nent sheets.
All l~ress f:e.l.ts will comp2ct in use to an e~tent related to thcir dcs.ign, compressibility lencJth press loading specd and contamination.
AS they compact the ability of the felt to accept water and to allow water passage through 1~ structure 15 reduc~s and this reduces tne a~ility of the felt to receive cont~minants because the compaction reduces the a~ailable vol~me in the felt ~tween the interstices thereof.
Tnus, the condition of the felt continuously deteri-orates throughout its li~e and its e~ficiency gradually 20 reduces. To o~rercome this the present methocl is to use a high-pressure needle~jet shower, operating at a pressure of say 35 ~g/cm2 "~lose high energy jets of ~later loosen the contaminants and -ebulk the felt~ The hi~h pressure is needed, to be e.~fectiv2, but i-he use of the sho~,ler is usually 25 discontinuous say 30 minutea per shift, or ir operated continuollslv the structure OL the elt ~tould be dama~et~.
1'he currt-~nk 5y5tem incorporates an intermitient hit~h-pressurt-~
!
- . :
;
l32 needle-jet, oscillating shower, to rebulk the felt~ a continuous, low~pressure fan shower to wash out the contaminants, and a Yacuum box to remove contaminated water from the felt.
All felts have their part~cular feltlwater ratio maximums, i.e.
saturation, and minimums, i.e. through Yacuum extraction, and they~operate within those limits, to accept water pressed out of the paper or board sheet.
If the ratio is high then the low pressure fan show.er is often not used because there is enough water to act as a contaminant transport for the vacuum box.
~lowever, the high-pressure, needle jet shower must be incorporated to maintain the bulk and the vacuum ~ox must be incorporated to remoYe the water from the paper.
It is an object of the present invention to ensure that the high pressure shower ;s used effectively to maintain the felt in good condition and so prolong its working life and to ensure efficient water extraction.
According to the invention a method of maintaining the permeability of felts in paper and board machines, comprises the following sequential steps:
(i) monitoring the permeability of the felt, (ii) sensing that the permeability of the felt has fallen to a first ~ ~ .
predetermined value, (iii) in response to sensing that the permeability of the felt has fallen to the first predetermined val-ue, directing at the felt at least one spray jet~
of liquid for reconditioning the felt and moving said at least one spray jet :~
widthwise of the felt in a cyclic movement to spray the entire width of the felt in each cycle, ~iv) sensing that the permeability of the felt has risen to a second predetermined value higher than the first value, (v) continuing to direct at the felt at least one spray jet of liquid for
2 ~ :
~ ~ ~3~3;~
reconditioning the felt until the end of the cycle of movement, and (vi) at the end of the cycle of movement, in response to sensing that the permeability of the felt has risen to the second pradetermined value, terminating the supply of liquid to the at least one jet.
Using a constant volume vacuum source, as is common, to draw water/air through the felt through a slotted or drilled top, on a vacuum box, the vacuum ::
level in the box becomes a measurement of resistance to flow. This resistance directly relates to the condit:ion of the felt and to its bulk or compaction and contamination and one preferred method according to the present invention is based upon the use of a vacuum level as a signal to control apparatus :~
sensitive to preset minimum/maximum vacuum levels for optimum felt condi- :
~2a~ ~
~ ~ ~3~3;~
reconditioning the felt until the end of the cycle of movement, and (vi) at the end of the cycle of movement, in response to sensing that the permeability of the felt has risen to the second pradetermined value, terminating the supply of liquid to the at least one jet.
Using a constant volume vacuum source, as is common, to draw water/air through the felt through a slotted or drilled top, on a vacuum box, the vacuum ::
level in the box becomes a measurement of resistance to flow. This resistance directly relates to the condit:ion of the felt and to its bulk or compaction and contamination and one preferred method according to the present invention is based upon the use of a vacuum level as a signal to control apparatus :~
sensitive to preset minimum/maximum vacuum levels for optimum felt condi- :
~2a~ ~
3~
~ 3 .
ti.on~ When the maximum level is reached, the high pressur2 needle jet sho~er will be activated. ~en tne minimum level is reached~ the snower is shut downO This is repeated throughout the ~elt l.ife.
Typically, the system would not activate in the first ~-3 days of a felt's life~ then it ~ould commence and increase, for say 80,'. of the e~pec~ted li:~e, then reduce becau.se o~ the effect of ~elt wearO
As has been stated above, the felt tends to compact 10 during use and, there-fore, the thickness of the fel.t also charac-terises its permeability.
Thu~, in another method accordin~ to the invent:iorl, monitoring o the permeability is effected by mon.i.t.oring the thickne.ss of the ~elt an~ br:ingi.n~ into operation the 15 stream of reconditioni.n~ liquid ~Then the th:ic]~n~ss re~che.s a predeterminecl ~lrst value and termil~ating the strearr. when.
the thickness i.ncreases to a pred.etermi.ned secorld value.
The th.ickness of the felt may ~e monitored b~ a rollex so mounted 2s to be bo~ily mova~le, the extent o~ the 20 movement characterising the thickness o~ the felt. The roller co~-operates w-ith another surface whi.ch may be that of ano~her roller and which provi~es a datu~n for the movab:Le xoller.
Alternatively, thickness changes may be determined 25 by a movable probe whose movement from a datl~um characterises the thi_kness of the felt. The mov~ le p-robe may be of shoe like form with a smoothly-rounded sole to a~oid damage to the felt or material thereon or it may be o~ calli.pe-f-li]~e form with suitably shaped surfaces, again to avo.id damage to 30 the felt~
Where the felt thic];ness is rnonitored, i.t is essen- ` ;
tial to pos~ lon the monitoring means at a position alon~
the len~th o the ~elt whe.fe che layer is not conveyin~
material ~he needle jet. shower is cor:~entionally oscill ated ~3~2 at a speed not related to the rate of movement of the felt. It is found that if the time cycle is short, uneven bulking of tKe felt results, and thus a further preferred feature of the invention is that the speed of oscillation should be one jet width per felt revolution to prelrent cross-overs and to provide even effect. As felt lengths are variable due to manufacturing tolerances, tension and time of life, and also due to speed, a signal can be taken either from the tensioner position and speed monitor, or a metal thread or other detectable insert in the felt. This signal is then used to control the cycle time of the oscillating shower. An over-ride is also incorporated in the control panel so that when the minimum vacuum level is reached the shower will continue to operate to the end of its stroke thus ensuring full and even coverage.
According to a second aspect of the invention apparatus for maintain-ing the permeability of f01ts in paper and board machines comprises:
(i) means for monitoring the permeability of the felt, (ii) a first sensor for sensing that the permeability of the felt has fallen to a first predetermined value, (iii) a second sensor for sens:ing that the permeability of the felt has risen to a second predetermined value higher than the first value, (iv) spray means for directing at the felt at least one spray jet o~
lirluid for reconditioning the felt, the spray means being movable cyclically,~
during operation, widthwise of the felt to spray every part of the entire width ~
of the felt in each cycle, and, ; ; ~ ;
~vl a control device connected to receiYe i`nputs from the first and second~
sensors and to provide an output to the spray means, the control device being responsive to a signal from the first sensor that the permeability of the felt has fallen to the first predetermined value to bring the spray means into operation, and being responsive to a signal from the second sensor that the
~ 3 .
ti.on~ When the maximum level is reached, the high pressur2 needle jet sho~er will be activated. ~en tne minimum level is reached~ the snower is shut downO This is repeated throughout the ~elt l.ife.
Typically, the system would not activate in the first ~-3 days of a felt's life~ then it ~ould commence and increase, for say 80,'. of the e~pec~ted li:~e, then reduce becau.se o~ the effect of ~elt wearO
As has been stated above, the felt tends to compact 10 during use and, there-fore, the thickness of the fel.t also charac-terises its permeability.
Thu~, in another method accordin~ to the invent:iorl, monitoring o the permeability is effected by mon.i.t.oring the thickne.ss of the ~elt an~ br:ingi.n~ into operation the 15 stream of reconditioni.n~ liquid ~Then the th:ic]~n~ss re~che.s a predeterminecl ~lrst value and termil~ating the strearr. when.
the thickness i.ncreases to a pred.etermi.ned secorld value.
The th.ickness of the felt may ~e monitored b~ a rollex so mounted 2s to be bo~ily mova~le, the extent o~ the 20 movement characterising the thickness o~ the felt. The roller co~-operates w-ith another surface whi.ch may be that of ano~her roller and which provi~es a datu~n for the movab:Le xoller.
Alternatively, thickness changes may be determined 25 by a movable probe whose movement from a datl~um characterises the thi_kness of the felt. The mov~ le p-robe may be of shoe like form with a smoothly-rounded sole to a~oid damage to the felt or material thereon or it may be o~ calli.pe-f-li]~e form with suitably shaped surfaces, again to avo.id damage to 30 the felt~
Where the felt thic];ness is rnonitored, i.t is essen- ` ;
tial to pos~ lon the monitoring means at a position alon~
the len~th o the ~elt whe.fe che layer is not conveyin~
material ~he needle jet. shower is cor:~entionally oscill ated ~3~2 at a speed not related to the rate of movement of the felt. It is found that if the time cycle is short, uneven bulking of tKe felt results, and thus a further preferred feature of the invention is that the speed of oscillation should be one jet width per felt revolution to prelrent cross-overs and to provide even effect. As felt lengths are variable due to manufacturing tolerances, tension and time of life, and also due to speed, a signal can be taken either from the tensioner position and speed monitor, or a metal thread or other detectable insert in the felt. This signal is then used to control the cycle time of the oscillating shower. An over-ride is also incorporated in the control panel so that when the minimum vacuum level is reached the shower will continue to operate to the end of its stroke thus ensuring full and even coverage.
According to a second aspect of the invention apparatus for maintain-ing the permeability of f01ts in paper and board machines comprises:
(i) means for monitoring the permeability of the felt, (ii) a first sensor for sensing that the permeability of the felt has fallen to a first predetermined value, (iii) a second sensor for sens:ing that the permeability of the felt has risen to a second predetermined value higher than the first value, (iv) spray means for directing at the felt at least one spray jet o~
lirluid for reconditioning the felt, the spray means being movable cyclically,~
during operation, widthwise of the felt to spray every part of the entire width ~
of the felt in each cycle, and, ; ; ~ ;
~vl a control device connected to receiYe i`nputs from the first and second~
sensors and to provide an output to the spray means, the control device being responsive to a signal from the first sensor that the permeability of the felt has fallen to the first predetermined value to bring the spray means into operation, and being responsive to a signal from the second sensor that the
-4- ~
permeability of the felt has risen to the second predete~nined value to continue the operation of the spray means until the end of a cycle of movement thereof and then to terminate the operation of the spray means.
The means may comprise at least one vacuum chamber over which the press felt passes in such manner that air can be drawn through the press felt into the chamber in order to detect the extent of the permeability of the felt. ;
The vacuum chamber may be additional to t~e vacuum box used to extract water from the felt and which forms a conventional feature of existing paper and board machines or where possible, or as e~plained above, the vacuum level~in the vacuum box may be used.
Alternatively, monitoring of the permeability may be effected by a~
device that is responsive to the thickness of the felt. Such a device inielates operation of the or each set oE spraying apparatus when the thickness reaches a pre~
: `:
~4a~
: , determincd va'~ue and terminates t'ne operati.on when the thic~ness reache.s a higher predete:rnine~d value.
~ he device may incorpora.te a roller whose bodily movement charac-terises the thickne~ss of the felt or it may compri.se probe~ or a sultable ro,rm of calliper.
The means may be so arrant~7ed that the or each set of 5pL aying apparatus is brought into use on detect.ion of a.
predeterm;.ned permeability condition of the felt and use of the apparatus ~er7ninated when another predetermined permea-.
10 bility condition is detected.
The or each set of sprayintr apparatus may be brought into use by the openint~ of a flow control val~e to admit cleaning and/or treatment liquid to the a,~paratus and/or by the enert.~lisation o a pump ~iose output supplie.~s high 15 pres3ure c:Leaning ant~/or treatment liquid to the apparatu,s.
. In at~.tl.ition, i~hert-~ the spraying apparatu~ incorpor-ates reciprocat:int"l SPraAY let5, the rt~ciprocatint.~ macchint-~ry may alsc~ be brougllt .into opera~ion, when re~qui.red, by the means .
The press felt may be of a compressible elt con-struc~.icjn or it ma.y be of ~.,he so~calle~. non~~c~mpressihle ~elt construction, the latter being, in l~ract.ice, com~ressihle to li.mited extentO
By way of example only, ernbcdiments of the invention 25 will now be ~escribed in ~reater detail wi'h re~erence to the ~ccom~anying drawings o~ which:-Fi~. 1 shows a first embodiment in diagr~natic -form only, . 2 s11o~s in schematic rorm a pneurmatic corltrol system for use with the embodiment of Fig. 1, Fi~. 3 ~ho~7s a schematic form part o-f an alternative en~bodiment or the in-~ention, and Fi.c~ ~ i;, an e~ lana-L.ory drawlng P~eferring irst to Fi.~ 1, a felt 1 in the îorm of a 35 closed 1oo~? pas~;e~ hetween the nip oi rollers 2, 3 which ~orm part o~ -che ~X'255 section of a paper ma]cing machine, o~rer an idler roller D- to a pc~sition adjacent to shower apparatus 5 which, when in use, dixects a .series of jets of water under high pressure, ~or e~ample, 35 I~g/c-Jn , towards the surface of the felt 1. Paper material 1a undergoing processing leaves the felt 1 after passing through bet~een the rollers 2, 3 as indicated in the drawing.
A low pressure shower 6 is used to s~ray water into ~he felt to ensuret in conjunction with a closely adjaceIlt 10 turning rollex 7, substantial saturation of the press felt.
The felt then passes over a conventional vacuur.~ ~o~ , Tlle ho~ has a sul~ort which supports the felt -as it ~asses. over ~.:
the bo~. The ~ox 8 is connected to a vaeuwm pum~ ~ to ~ -esta~li.sh ~ partial vacuum therein. : :
The extent of the partial vacuum in the box 8 is conveyecl via lins 10 to control apparatus shown as block 11 wh.ic1l is adapted to control the o,~sration of the sho~er apparatus 5 i.n dependence upon the vacuum conditions e~ist ing in the bo~ S and the speed of the felt.
The control apparatus also receives an input from a sensor indicated diagrammatically at 1? responsive to the movement of the felt and which act.s to signal to khe apparatus each complete revolution o-E the felt.
Tension in the felt is maintained by tensioning mean~ :
25 13 of any conven-tional form whils~ ~urning rollers 1~ and 16 guide the felt bac~; to the nip o~ the rollers 2 and 3~ Be-~ween the turning rollers is an alignment roller 15 which ~ :
keeps the press felt in alignment with the rollers 14 and :~
16.
~en new or after reconditioning, the felt may have a thickness typically of say ~6 mm but during use this reduces and may reach a value as low as 1 mm~
~en in its new condition, the felt, in passing over the vacuurl ch~bers, se~ up a pa~tial ~acuum t~erein of say 3~ 0.05 M Hg ancl this is insufficient to bring the shower apparatus 5 into opera-tiorlA Howe~er, when the felt has been compressed to a thickness of say 2 rnm, the partial vacuum has changed to, say 0~0 ~5I-Ig and this '~rings the shower c~ppara-tus into use.
The action of the jets of water is to reconciition the felt and the latter increases ln thic'~ness as it leaves ~he v:ic.inlty of ~he shower apparatusD ~lthough there is a degree of compression oF the felt as it next passes through the nîp of the rollers 2, 3, there is a further recondition--10 ing effected by the shower apparatus and this conti.nues until.
the partial vacuum conditions in the box 8 reach a vall~e indicating -that a desired reconditioning has been achievecl and the control apparatus 11 then terrninates the s'nower.
The cycle repeats when ne~t the degree of compressio~
15 o~ the felt xeaches a value at which the control. appa?^a-~11 lnitiates the shower again.
FigO 2 shows in cdiagramrnatic fo~ only a h.ig'h press~
ure needlc ~et sho~er 17 ~lch may be of the fo.rm descxibed in ~uropean Patent Specification No. 0009399 (Application ..
-~20 ~.~o. 7~30~9~2.3). Shower 17 is powered by a pneumatic moto~
indicatcd by block 18 fed with compressed air v~.a control line 19 Fig. 2 also shows the vacuum box 8 and ~he vacllum pump 9 and although Fig. 2 shows those compon~Qnts in close 25 pro~imity to show~r ,7, this is not no?:mally the case in practice. The vacuurn inside bo~ 8 is communicated to control apparatus via line 20, a filter 21 being included to pr~vQnt the transmi.~ion along the line 20 of any con~clminants that may be present.
~ine 20 is connected to a sensor 21 comprising a housing with an internal. chamber divided into two parts by a f~e~ible diaphrac~1 22, 1ine 20 being connected to one oF the chamher ~art,s. The diaphrac~m ls resilient3.y-].oaded as indl-cated diacJra~unatically by ~ring 23 and the 7Oading is 35 ac1justahle via a manual control ~
z : `
, In practice, the diaphragm 22 may be spring loaded or .it may be loaded by r~.eans of a variable pneumatic pressul-e .
JJinked to the dlaphragm 22 is a pneuma`ic control
permeability of the felt has risen to the second predete~nined value to continue the operation of the spray means until the end of a cycle of movement thereof and then to terminate the operation of the spray means.
The means may comprise at least one vacuum chamber over which the press felt passes in such manner that air can be drawn through the press felt into the chamber in order to detect the extent of the permeability of the felt. ;
The vacuum chamber may be additional to t~e vacuum box used to extract water from the felt and which forms a conventional feature of existing paper and board machines or where possible, or as e~plained above, the vacuum level~in the vacuum box may be used.
Alternatively, monitoring of the permeability may be effected by a~
device that is responsive to the thickness of the felt. Such a device inielates operation of the or each set oE spraying apparatus when the thickness reaches a pre~
: `:
~4a~
: , determincd va'~ue and terminates t'ne operati.on when the thic~ness reache.s a higher predete:rnine~d value.
~ he device may incorpora.te a roller whose bodily movement charac-terises the thickne~ss of the felt or it may compri.se probe~ or a sultable ro,rm of calliper.
The means may be so arrant~7ed that the or each set of 5pL aying apparatus is brought into use on detect.ion of a.
predeterm;.ned permeability condition of the felt and use of the apparatus ~er7ninated when another predetermined permea-.
10 bility condition is detected.
The or each set of sprayintr apparatus may be brought into use by the openint~ of a flow control val~e to admit cleaning and/or treatment liquid to the a,~paratus and/or by the enert.~lisation o a pump ~iose output supplie.~s high 15 pres3ure c:Leaning ant~/or treatment liquid to the apparatu,s.
. In at~.tl.ition, i~hert-~ the spraying apparatu~ incorpor-ates reciprocat:int"l SPraAY let5, the rt~ciprocatint.~ macchint-~ry may alsc~ be brougllt .into opera~ion, when re~qui.red, by the means .
The press felt may be of a compressible elt con-struc~.icjn or it ma.y be of ~.,he so~calle~. non~~c~mpressihle ~elt construction, the latter being, in l~ract.ice, com~ressihle to li.mited extentO
By way of example only, ernbcdiments of the invention 25 will now be ~escribed in ~reater detail wi'h re~erence to the ~ccom~anying drawings o~ which:-Fi~. 1 shows a first embodiment in diagr~natic -form only, . 2 s11o~s in schematic rorm a pneurmatic corltrol system for use with the embodiment of Fig. 1, Fi~. 3 ~ho~7s a schematic form part o-f an alternative en~bodiment or the in-~ention, and Fi.c~ ~ i;, an e~ lana-L.ory drawlng P~eferring irst to Fi.~ 1, a felt 1 in the îorm of a 35 closed 1oo~? pas~;e~ hetween the nip oi rollers 2, 3 which ~orm part o~ -che ~X'255 section of a paper ma]cing machine, o~rer an idler roller D- to a pc~sition adjacent to shower apparatus 5 which, when in use, dixects a .series of jets of water under high pressure, ~or e~ample, 35 I~g/c-Jn , towards the surface of the felt 1. Paper material 1a undergoing processing leaves the felt 1 after passing through bet~een the rollers 2, 3 as indicated in the drawing.
A low pressure shower 6 is used to s~ray water into ~he felt to ensuret in conjunction with a closely adjaceIlt 10 turning rollex 7, substantial saturation of the press felt.
The felt then passes over a conventional vacuur.~ ~o~ , Tlle ho~ has a sul~ort which supports the felt -as it ~asses. over ~.:
the bo~. The ~ox 8 is connected to a vaeuwm pum~ ~ to ~ -esta~li.sh ~ partial vacuum therein. : :
The extent of the partial vacuum in the box 8 is conveyecl via lins 10 to control apparatus shown as block 11 wh.ic1l is adapted to control the o,~sration of the sho~er apparatus 5 i.n dependence upon the vacuum conditions e~ist ing in the bo~ S and the speed of the felt.
The control apparatus also receives an input from a sensor indicated diagrammatically at 1? responsive to the movement of the felt and which act.s to signal to khe apparatus each complete revolution o-E the felt.
Tension in the felt is maintained by tensioning mean~ :
25 13 of any conven-tional form whils~ ~urning rollers 1~ and 16 guide the felt bac~; to the nip o~ the rollers 2 and 3~ Be-~ween the turning rollers is an alignment roller 15 which ~ :
keeps the press felt in alignment with the rollers 14 and :~
16.
~en new or after reconditioning, the felt may have a thickness typically of say ~6 mm but during use this reduces and may reach a value as low as 1 mm~
~en in its new condition, the felt, in passing over the vacuurl ch~bers, se~ up a pa~tial ~acuum t~erein of say 3~ 0.05 M Hg ancl this is insufficient to bring the shower apparatus 5 into opera-tiorlA Howe~er, when the felt has been compressed to a thickness of say 2 rnm, the partial vacuum has changed to, say 0~0 ~5I-Ig and this '~rings the shower c~ppara-tus into use.
The action of the jets of water is to reconciition the felt and the latter increases ln thic'~ness as it leaves ~he v:ic.inlty of ~he shower apparatusD ~lthough there is a degree of compression oF the felt as it next passes through the nîp of the rollers 2, 3, there is a further recondition--10 ing effected by the shower apparatus and this conti.nues until.
the partial vacuum conditions in the box 8 reach a vall~e indicating -that a desired reconditioning has been achievecl and the control apparatus 11 then terrninates the s'nower.
The cycle repeats when ne~t the degree of compressio~
15 o~ the felt xeaches a value at which the control. appa?^a-~11 lnitiates the shower again.
FigO 2 shows in cdiagramrnatic fo~ only a h.ig'h press~
ure needlc ~et sho~er 17 ~lch may be of the fo.rm descxibed in ~uropean Patent Specification No. 0009399 (Application ..
-~20 ~.~o. 7~30~9~2.3). Shower 17 is powered by a pneumatic moto~
indicatcd by block 18 fed with compressed air v~.a control line 19 Fig. 2 also shows the vacuum box 8 and ~he vacllum pump 9 and although Fig. 2 shows those compon~Qnts in close 25 pro~imity to show~r ,7, this is not no?:mally the case in practice. The vacuurn inside bo~ 8 is communicated to control apparatus via line 20, a filter 21 being included to pr~vQnt the transmi.~ion along the line 20 of any con~clminants that may be present.
~ine 20 is connected to a sensor 21 comprising a housing with an internal. chamber divided into two parts by a f~e~ible diaphrac~1 22, 1ine 20 being connected to one oF the chamher ~art,s. The diaphrac~m ls resilient3.y-].oaded as indl-cated diacJra~unatically by ~ring 23 and the 7Oading is 35 ac1justahle via a manual control ~
z : `
, In practice, the diaphragm 22 may be spring loaded or .it may be loaded by r~.eans of a variable pneumatic pressul-e .
JJinked to the dlaphragm 22 is a pneuma`ic control
5 valve 25 adapted to join an outlet line 26 either to atmos-pl~ere at outlet 27 or to a source of compressed air via inlet 28.
Line 26 is joined to a flrst act.uator of another pneumat.i.c control valve 29 operable to connect line 19 10 either to atmospllere a-t outlet 30 or to a connecting llne 31.
Also connected to line 20 is a second sensor 32 ~ to~se~
construction is si~nllar to that of SenSQr ~1 exce~t that the diaphra~Jmt loading is preset by means of control 33 ancl once pre.set is not normall~ adjusted by the user. The c1iaæhrac~t 15 i.s pneulttati.call.y loaded.
Linked to the diaphragnt of sensor 32 is a pneuma~ic control valve 34 movable to connect output l.ine 35 either to ~ ~ ;
atmosX~ere at outiet 3G or co the source o~ cont,pressed air via input 37.
-- ~o Line 35 is joined to a devic~ 3~ for emitt.in~ a visual warning. Devic~ 3~ may comprise an electric light connectable to a power source (not shown~ by msans ~L a pres-sure responsive switch (not shown~ that is controlled by pressure changes in line 35t Line 35 is also ~onnected to a reservo.ir valve 39 having a thr~ttled outlet 40 to a~os,~here, and a first output 41 joinecl directly to a ~neumatic actuator 42 ~or control vaJ.ve 43~ The actuator 42 operates again~t a: spring bias ~4. Control valve 43 is adapted to connect out~ut line 30 4S ei.ther to the source of compressed air via inlet 46 or to atmosphere via outlet 47. ~eservoir valve 39 also has a second ou'let 48 connected to act.uator 4~ vi.a adjustable thrott.~e~s 49, 50.
~utput line 4S is connec._ed to a klaxon ~1 which 35 provide,s, as wiil be descri1~ed later, an aud.ibl~ warnln~7 in ~ .
: .
8~
the event tha~ the vacuum in the box 8 reaches a VQry high value~
ELot~ line 20 is also joined to a furtht*r sensor 52 whose construction is identical to -that of sensor 21. Sensor 52 operates a pneumatic flow control valve 53 connect?d to join an output line 5~ either to a~nosphere Vi3. outlet 55 or to the source o~ compressed air via iniet 56.
Output line 5~* is joined to a second actuator o~ the control valve 29 as shownO
Flow line .20 is also joined to yet another sensor 57 whose construc-l.on is the same as tha. of sensor 32 and w-hich controls the o~ratlon of ~low valve 58~ Flow valve 58 ls connect.?d to joln an output llne 59 either to atmosph-*re at outlet 60 or to the source of compressed air at 61 Output line 59 is connected to actuate a visual warnin~ ht 62 and also to actuate another ~lo~ control valve 63 connected in the line 31 to valve 29.
Valve 6~ is ~apted to connect line 31 either to at;nosphere at outlet 6~ or to line ~5 itsel~ connec~ecl to -- 20 mair manuall~-o~erated flo~t control v~lve 66L ~alve 66 has a control l;nob 67 rotation of which a~inst the bia~ing of a Spri!lg 68 opens the valve to connect line 65 to the source . of co~.npressed air shown as bo~ 69 and wllich may be a com~
pressor or some other source o~ compressed air or to atmos-25 phere at outl.et 7Q
Sensor 21 is loaded t~ a va~.ue detenmined ~y theworking conditions and the nature of the felt in use to connect line 26 to source 28 when the vacuum conditions in box 8 reach a hi~h value indicatin~ that the felt has com-~0 pacted to an e~tent suf~iclent to efect deleteriously ~he : :e~traction o liquid therefrom~ The application o-- pneuma~c pxe~sure to line 26 causes the first actuaior o~ valve 29 to connect line 19 to line 31 and on the assumption that. valv~3 5~ and 66 are in the positions sho~7n ~neul1atic pressur~ will 35 be applj.ed to line 19 and this will initiate operation 3~98Z
o~ t.he hl(~h pre.ssur2 sho~rer 17.
~ s the spray operates, it rebulks the ~elt and the :
vacuum in hoY~ ~ drops to a value at which sen~or 21 re1.eases and sen~or 55 responds. l'he second actuator of valve 29 l~ ~ :
5 pres,surised at the first connected to atmosphere via line ::
26 and valve 25. The position o. valve 29 changes and line 19 i.s connected to atmosphere and the spraying operation at shower l7 is termi.nated.
This process repeats as the permea.oility conc1itions 10 Of the felt require.
I~, for some reason, the vacuum in box 9 conJ-inues ~:
to rise above the value to which sensor 21 is set, sensor 32 w.ill respond anc-l v~lve 3~ will cause pneumatic pres~ure to he avpli.ed to line 35 thus energising warning liqlit ~.3 anr.l 1S c~.usi.ng k.laxon 51 to sound via the conventional energisincJ
circuit declcri.bed above. The on-of~ periods of the k1a~on are detexmined by the settin~s o the variable ~hrottles ~9, Similarly, iI the vacuum r~ressuxe in box 8I con-~ :
2.0 ti.nues to drol~ belo~ the v?~lue at ~hlch 3ensor 55 responds, .f;ensor 57 will then respond and vi.a valve 5~, warning light 62 ~'Jill be energise~.
The manual conJcrol knobs of sensors 21 and 52 are mounted upon the ~ront of control box 11 so that they can 25 be set by a user. A pneumatic gauge 71 is also mounted upon the front o the control box to enable ~he user to ma~e the : appropriate adjustments to the setting of the sensors 21 and ~ ~
52. : ~:
A second pneumatic yauge 72 is located wi.thin the :~
30 contrc)l box close to the preset controls for the sensors 32 ancl 57 so that the latter can be pre&et. to tha desired values~ I-t will be appreciated tha-t ~auge 71 may not be visible during the sett.ing of sensors 32 and 57. ~ ~.
A furthec w~rnlng light 73 indicates whei~ the manu-35 ally operated ~;alve ~o is actuatecl to its "O.N" position 38;~
allowlng ~.ir un3er ~ressure into line 65.
Figy 3 ~hows in dia~rar~matic form a form of devicefor se~lng t~e thickness oF the felt shown at 1. A
calJ.i~er-lihe :frame 7~ sllpport~ probes ln the form of shoes 75, 76 wllose rou.nded sur~aces licJhtly contactt the upper and lower sur~aces ~~e,spectiv21y of -the ~elt 1. ~ least the up~er shoe i.3 liglltly 'Sp- i.n~-loaded to enable lt to follo~
vari.ati.ons :in ~,he i~nic~cness of the .elt 1.
Shoe 75 i5 movable vertjcally in the call:iper and 10 .it.s moveI~ent- is sen.sed by a sen.sor 77 whose out~u-t 7~ is used, ,.n a manner similar to tl~at o~ the sensors ~1 anc! 5.?. ~;
'c.o initiate and termi.nate operation of the high pressure spray a Sul~a~le saf-ecJuards are pro~.i.c1ed ~o sense~ e~ccessive 15 cor[l~ac~c.i.on of the ~elt also e~cesslve "re-bulk.ing" ancl these sa~ecJuard.s opera~.e in a manner ana.logous to tho~e desc-fi~sd above w:ith re*erQnce to ~l~J~ 2.
I:f c7~e~ired, the shoes can be traversed cycl.ic,Yally acro3s the width o~ t,lle -.celt~ Such movement may be achieved ~0 in an~ ~onvenient manner, ~or e,Y~ample by a ~ne~atic or eleo~t~ic rnotor c)r by a ,~iston-cylinder arx~n~ent. This is indicated diacJram~atically in Fig. 3 by ~he dotted rectangle ~;~
79.
It 7s possible to traverse the higll pressure spray 25 in s~nchronism ~ith the shoe~
The use o~ relatively small arPa shoes make~ it pos~ible to cletect localised areas of web compaction. For e~np'e, and as shown in Fig. 4, the web 1 may have reachecl a concl:ltion in ~hich a lonyitudinal area 80 e~ists over 30 which a xelcLtively high cleyree of compaction of the felt exists anc1 ano'-her longitudinal axea ~1 over ~hich a rela-tive1~ lo~l c'ecree of com~action e,~ls~s.
the ~acuum box technique descrihed above is us~d, the bo: ~ rc;iny 5ho~:~n ill Fiy. ~, the existence o~ tl~e are~s 35 ~t) and Si ~ould ~robahly remain unce~tectecl hut a shoe, shown ~~ 12 ~
al ~2 in Fi~ ~' r moving acro3s the fe] t w:lll detect the areas and bxing the spray i.n.o operation ~s necessary to " re~buik" area ~30 .
l~e:l~erence has b~en made above -to the sto~ in~,r o the 5 .spra~T onl~ at the end of a cyc1e of movement.~ This ma~ be achieved ln a nurr~e:r of ways, ' or e~am~le a ~ontroi line ~3 - shown dotted i.n Fig. 2 i.s used to control a vGlve 84 in li.ne 54 whicll preve~ s eller~isation o~ the s~cond act~la~or o~ al~.T~ .?'~
Line 26 is joined to a flrst act.uator of another pneumat.i.c control valve 29 operable to connect line 19 10 either to atmospllere a-t outlet 30 or to a connecting llne 31.
Also connected to line 20 is a second sensor 32 ~ to~se~
construction is si~nllar to that of SenSQr ~1 exce~t that the diaphra~Jmt loading is preset by means of control 33 ancl once pre.set is not normall~ adjusted by the user. The c1iaæhrac~t 15 i.s pneulttati.call.y loaded.
Linked to the diaphragnt of sensor 32 is a pneuma~ic control valve 34 movable to connect output l.ine 35 either to ~ ~ ;
atmosX~ere at outiet 3G or co the source o~ cont,pressed air via input 37.
-- ~o Line 35 is joined to a devic~ 3~ for emitt.in~ a visual warning. Devic~ 3~ may comprise an electric light connectable to a power source (not shown~ by msans ~L a pres-sure responsive switch (not shown~ that is controlled by pressure changes in line 35t Line 35 is also ~onnected to a reservo.ir valve 39 having a thr~ttled outlet 40 to a~os,~here, and a first output 41 joinecl directly to a ~neumatic actuator 42 ~or control vaJ.ve 43~ The actuator 42 operates again~t a: spring bias ~4. Control valve 43 is adapted to connect out~ut line 30 4S ei.ther to the source of compressed air via inlet 46 or to atmosphere via outlet 47. ~eservoir valve 39 also has a second ou'let 48 connected to act.uator 4~ vi.a adjustable thrott.~e~s 49, 50.
~utput line 4S is connec._ed to a klaxon ~1 which 35 provide,s, as wiil be descri1~ed later, an aud.ibl~ warnln~7 in ~ .
: .
8~
the event tha~ the vacuum in the box 8 reaches a VQry high value~
ELot~ line 20 is also joined to a furtht*r sensor 52 whose construction is identical to -that of sensor 21. Sensor 52 operates a pneumatic flow control valve 53 connect?d to join an output line 5~ either to a~nosphere Vi3. outlet 55 or to the source o~ compressed air via iniet 56.
Output line 5~* is joined to a second actuator o~ the control valve 29 as shownO
Flow line .20 is also joined to yet another sensor 57 whose construc-l.on is the same as tha. of sensor 32 and w-hich controls the o~ratlon of ~low valve 58~ Flow valve 58 ls connect.?d to joln an output llne 59 either to atmosph-*re at outlet 60 or to the source of compressed air at 61 Output line 59 is connected to actuate a visual warnin~ ht 62 and also to actuate another ~lo~ control valve 63 connected in the line 31 to valve 29.
Valve 6~ is ~apted to connect line 31 either to at;nosphere at outlet 6~ or to line ~5 itsel~ connec~ecl to -- 20 mair manuall~-o~erated flo~t control v~lve 66L ~alve 66 has a control l;nob 67 rotation of which a~inst the bia~ing of a Spri!lg 68 opens the valve to connect line 65 to the source . of co~.npressed air shown as bo~ 69 and wllich may be a com~
pressor or some other source o~ compressed air or to atmos-25 phere at outl.et 7Q
Sensor 21 is loaded t~ a va~.ue detenmined ~y theworking conditions and the nature of the felt in use to connect line 26 to source 28 when the vacuum conditions in box 8 reach a hi~h value indicatin~ that the felt has com-~0 pacted to an e~tent suf~iclent to efect deleteriously ~he : :e~traction o liquid therefrom~ The application o-- pneuma~c pxe~sure to line 26 causes the first actuaior o~ valve 29 to connect line 19 to line 31 and on the assumption that. valv~3 5~ and 66 are in the positions sho~7n ~neul1atic pressur~ will 35 be applj.ed to line 19 and this will initiate operation 3~98Z
o~ t.he hl(~h pre.ssur2 sho~rer 17.
~ s the spray operates, it rebulks the ~elt and the :
vacuum in hoY~ ~ drops to a value at which sen~or 21 re1.eases and sen~or 55 responds. l'he second actuator of valve 29 l~ ~ :
5 pres,surised at the first connected to atmosphere via line ::
26 and valve 25. The position o. valve 29 changes and line 19 i.s connected to atmosphere and the spraying operation at shower l7 is termi.nated.
This process repeats as the permea.oility conc1itions 10 Of the felt require.
I~, for some reason, the vacuum in box 9 conJ-inues ~:
to rise above the value to which sensor 21 is set, sensor 32 w.ill respond anc-l v~lve 3~ will cause pneumatic pres~ure to he avpli.ed to line 35 thus energising warning liqlit ~.3 anr.l 1S c~.usi.ng k.laxon 51 to sound via the conventional energisincJ
circuit declcri.bed above. The on-of~ periods of the k1a~on are detexmined by the settin~s o the variable ~hrottles ~9, Similarly, iI the vacuum r~ressuxe in box 8I con-~ :
2.0 ti.nues to drol~ belo~ the v?~lue at ~hlch 3ensor 55 responds, .f;ensor 57 will then respond and vi.a valve 5~, warning light 62 ~'Jill be energise~.
The manual conJcrol knobs of sensors 21 and 52 are mounted upon the ~ront of control box 11 so that they can 25 be set by a user. A pneumatic gauge 71 is also mounted upon the front o the control box to enable ~he user to ma~e the : appropriate adjustments to the setting of the sensors 21 and ~ ~
52. : ~:
A second pneumatic yauge 72 is located wi.thin the :~
30 contrc)l box close to the preset controls for the sensors 32 ancl 57 so that the latter can be pre&et. to tha desired values~ I-t will be appreciated tha-t ~auge 71 may not be visible during the sett.ing of sensors 32 and 57. ~ ~.
A furthec w~rnlng light 73 indicates whei~ the manu-35 ally operated ~;alve ~o is actuatecl to its "O.N" position 38;~
allowlng ~.ir un3er ~ressure into line 65.
Figy 3 ~hows in dia~rar~matic form a form of devicefor se~lng t~e thickness oF the felt shown at 1. A
calJ.i~er-lihe :frame 7~ sllpport~ probes ln the form of shoes 75, 76 wllose rou.nded sur~aces licJhtly contactt the upper and lower sur~aces ~~e,spectiv21y of -the ~elt 1. ~ least the up~er shoe i.3 liglltly 'Sp- i.n~-loaded to enable lt to follo~
vari.ati.ons :in ~,he i~nic~cness of the .elt 1.
Shoe 75 i5 movable vertjcally in the call:iper and 10 .it.s moveI~ent- is sen.sed by a sen.sor 77 whose out~u-t 7~ is used, ,.n a manner similar to tl~at o~ the sensors ~1 anc! 5.?. ~;
'c.o initiate and termi.nate operation of the high pressure spray a Sul~a~le saf-ecJuards are pro~.i.c1ed ~o sense~ e~ccessive 15 cor[l~ac~c.i.on of the ~elt also e~cesslve "re-bulk.ing" ancl these sa~ecJuard.s opera~.e in a manner ana.logous to tho~e desc-fi~sd above w:ith re*erQnce to ~l~J~ 2.
I:f c7~e~ired, the shoes can be traversed cycl.ic,Yally acro3s the width o~ t,lle -.celt~ Such movement may be achieved ~0 in an~ ~onvenient manner, ~or e,Y~ample by a ~ne~atic or eleo~t~ic rnotor c)r by a ,~iston-cylinder arx~n~ent. This is indicated diacJram~atically in Fig. 3 by ~he dotted rectangle ~;~
79.
It 7s possible to traverse the higll pressure spray 25 in s~nchronism ~ith the shoe~
The use o~ relatively small arPa shoes make~ it pos~ible to cletect localised areas of web compaction. For e~np'e, and as shown in Fig. 4, the web 1 may have reachecl a concl:ltion in ~hich a lonyitudinal area 80 e~ists over 30 which a xelcLtively high cleyree of compaction of the felt exists anc1 ano'-her longitudinal axea ~1 over ~hich a rela-tive1~ lo~l c'ecree of com~action e,~ls~s.
the ~acuum box technique descrihed above is us~d, the bo: ~ rc;iny 5ho~:~n ill Fiy. ~, the existence o~ tl~e are~s 35 ~t) and Si ~ould ~robahly remain unce~tectecl hut a shoe, shown ~~ 12 ~
al ~2 in Fi~ ~' r moving acro3s the fe] t w:lll detect the areas and bxing the spray i.n.o operation ~s necessary to " re~buik" area ~30 .
l~e:l~erence has b~en made above -to the sto~ in~,r o the 5 .spra~T onl~ at the end of a cyc1e of movement.~ This ma~ be achieved ln a nurr~e:r of ways, ' or e~am~le a ~ontroi line ~3 - shown dotted i.n Fig. 2 i.s used to control a vGlve 84 in li.ne 54 whicll preve~ s eller~isation o~ the s~cond act~la~or o~ al~.T~ .?'~
Claims (11)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of maintaining the permeability of felts in paper and board machines, the method comprising the following sequential steps:
(i) monitoring the permeability of the felt, (ii) sensing that the permeability of the felt has fallen to a first predetermined value, (iii) in response to sensing that the permeability of the felt has fallen to the first predetermined value, directing at the felt at least one spray jet of liquid for reconditioning the felt and moving said at least one spray jet widthwise of the felt in a cyclic movement to spray the entire width of the felt in each cycle, (iv) sensing that the permeability of the felt has risen to a second predetermined value higher than the first value, (v) continuing to direct at the felt at least one spray jet of liquid for reconditioning the felt until the end of the cycle of movement, and (vi) at the end of the cycle of movement, in response to sensing that the permeability of the felt has risen to the second predetermined value, terminating the supply of liquid to the at least one jet.
(i) monitoring the permeability of the felt, (ii) sensing that the permeability of the felt has fallen to a first predetermined value, (iii) in response to sensing that the permeability of the felt has fallen to the first predetermined value, directing at the felt at least one spray jet of liquid for reconditioning the felt and moving said at least one spray jet widthwise of the felt in a cyclic movement to spray the entire width of the felt in each cycle, (iv) sensing that the permeability of the felt has risen to a second predetermined value higher than the first value, (v) continuing to direct at the felt at least one spray jet of liquid for reconditioning the felt until the end of the cycle of movement, and (vi) at the end of the cycle of movement, in response to sensing that the permeability of the felt has risen to the second predetermined value, terminating the supply of liquid to the at least one jet.
2. A method as claimed in claim 1 including the step of applying to the felt a vacuum generated by a constant vacuum source, and in which the permeability of the felt is monitored by means responsive to the vacuum applied to the felt.
3. A method as claimed in claim 2 in which the vacuum is that applied to the felt to extract water therefrom.
4. A method as claimed in claim 1 in which the permeability of the felt is monitored by sensing changes in the thickness of the felt.
5. A method as claimed in claim 1 which further includes the steps of sensing the speed of the felt passed the apparatus and of using the value of the sensed speed to determine the dura-tion of each said cycle.
6. A method as claimed in claim 1 in which the jet completes a movement equal to the diameter thereof during each revolution of the felt.
7. Apparatus for maintaining the permeability of felts in paper and board machines, the apparatus comprising:
(i) means for monitoring the permeability of the felt, (ii) a first sensor for sensing that the permeability of the felt has fallen to a first predetermined value, (iii) a second sensor for sensing that the permeability of the felt has risen to a second predetermined value higher than the first value, (iv) spray means for directing at the felt at least one spray jet of liquid for reconditioning the felt, the spray means being movable cyclically, during operation, widthwise of the felt to spray every part of the entire width of the felt in each cycle, and, (v) a control device connected to receive inputs from the first and second sensors and to provide an output to the spray means, the control device being responsive to a signal from the first sensor that the permeability of the felt has fallen to the first predetermined value to bring the spray means into operation, and being responsive to a signal from the second sensor that the permeability of the felt has risen to the second predetermined value to continue the operation of the spray means until the end of a cycle of movement thereof and then to terminate the operation of the spray means.
(i) means for monitoring the permeability of the felt, (ii) a first sensor for sensing that the permeability of the felt has fallen to a first predetermined value, (iii) a second sensor for sensing that the permeability of the felt has risen to a second predetermined value higher than the first value, (iv) spray means for directing at the felt at least one spray jet of liquid for reconditioning the felt, the spray means being movable cyclically, during operation, widthwise of the felt to spray every part of the entire width of the felt in each cycle, and, (v) a control device connected to receive inputs from the first and second sensors and to provide an output to the spray means, the control device being responsive to a signal from the first sensor that the permeability of the felt has fallen to the first predetermined value to bring the spray means into operation, and being responsive to a signal from the second sensor that the permeability of the felt has risen to the second predetermined value to continue the operation of the spray means until the end of a cycle of movement thereof and then to terminate the operation of the spray means.
8. Apparatus as claimed in claim 7 and further comprising a vacuum-operated device for applying a vacuum to the felt, and in which the monitoring means is such as to respond to the degree of vacuum in the vacuum chamber of the device.
9. Apparatus as claimed in claim 7 and further comprising a vacuum-operated liquid extraction device for removing liquid from the felt, and in which the monitoring means is such as to respond to the degree of vacuum in the vacuum chamber of the device.
10. Apparatus as claimed in claim 7 in which there is prov-ided a device responsive to changes in the thickness of the felt for monitoring changes in the permeability thereof.
11. Apparatus as claimed in claim 7 in which the spray means includes a series of spaced spray jets and an arrangement for reciprocating the spray jets across the width of the felt, and in which there is included means responsive to the speed of the felt and whose output is used to control the duration of each said cycle.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7928596 | 1979-08-16 | ||
| GB7928596 | 1979-08-16 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1143982A true CA1143982A (en) | 1983-04-05 |
Family
ID=10507254
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000358375A Expired CA1143982A (en) | 1979-08-16 | 1980-08-15 | Apparatus and method for maintaining the permeability of paper and board machine felts |
Country Status (9)
| Country | Link |
|---|---|
| EP (1) | EP0024205B1 (en) |
| AU (1) | AU536648B2 (en) |
| BR (1) | BR8005192A (en) |
| CA (1) | CA1143982A (en) |
| DE (1) | DE3069420D1 (en) |
| FI (1) | FI802545A (en) |
| MX (1) | MX153235A (en) |
| NZ (1) | NZ194626A (en) |
| ZA (1) | ZA804983B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5135615A (en) * | 1990-07-03 | 1992-08-04 | Tamfelt Oy Ab | Device for measuring the condition of a felt and for reconditioning it |
| US5349845A (en) * | 1992-04-07 | 1994-09-27 | Tamfelt Oy Ab | Apparatus for measuring the condition of a felt in a paper machine |
| US5964956A (en) * | 1997-06-25 | 1999-10-12 | Voith Sulzer Papiermaschinen Gmbh | Process for cleaning a transport belt |
| US6143092A (en) * | 1997-06-25 | 2000-11-07 | Voith Sulzer Papiermaschinen Gmbh | Process for cleaning a transport belt |
Families Citing this family (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2604199B1 (en) * | 1986-09-18 | 1988-12-09 | Technopap | CONTINUOUS BELT CLEANER PERMEABLE TO FLOWING FLUIDS, IN PARTICULAR CANVAS CLEANER FOR PAPER MACHINE, AND MACHINES EQUIPPED WITH SUCH A CLEANER. |
| GB8903357D0 (en) * | 1989-02-14 | 1989-04-05 | Morley Michael J | Improvements in and relating to shower installations for paper making machines |
| FI97632B (en) * | 1995-01-23 | 1996-10-15 | Ev Group Oy | Method for washing tissues, especially paper machine tissues |
| DE19806078A1 (en) * | 1998-02-14 | 1999-08-19 | Voith Sulzer Papiertech Patent | Method and device for cleaning |
| DE10102199A1 (en) | 2001-01-18 | 2002-08-01 | Voith Paper Patent Gmbh | Process for conditioning a circulating felt belt |
| EP1353008A1 (en) * | 2002-03-01 | 2003-10-15 | Voith Paper Patent GmbH | Method and apparatus for measuring the hardness or compactness of a clothing |
| EP1342839B1 (en) | 2002-03-01 | 2006-11-22 | Voith Patent GmbH | Method and apparatus for measuring the hardness or compactness of a clothing |
| DE10343913A1 (en) | 2003-09-19 | 2005-06-09 | Voith Paper Patent Gmbh | Apparatus and method for determining the permeability of a circulating belt |
| DE102011079060A1 (en) | 2011-07-13 | 2013-01-17 | Voith Patent Gmbh | Method and device for condition monitoring of a clothing |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA985543A (en) * | 1973-01-05 | 1976-03-16 | James Haythornthwaite | Felt cleaner with moisture control for paper making machines |
| US3910815A (en) * | 1974-03-26 | 1975-10-07 | Westvaco Corp | Method and apparatus for papermachine felt cleaning |
-
1980
- 1980-08-11 NZ NZ194626A patent/NZ194626A/en unknown
- 1980-08-12 AU AU61383/80A patent/AU536648B2/en not_active Ceased
- 1980-08-13 FI FI802545A patent/FI802545A/en not_active Application Discontinuation
- 1980-08-14 EP EP80302805A patent/EP0024205B1/en not_active Expired
- 1980-08-14 DE DE8080302805T patent/DE3069420D1/en not_active Expired
- 1980-08-14 ZA ZA00804983A patent/ZA804983B/en unknown
- 1980-08-15 BR BR8005192A patent/BR8005192A/en unknown
- 1980-08-15 MX MX183565A patent/MX153235A/en unknown
- 1980-08-15 CA CA000358375A patent/CA1143982A/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5135615A (en) * | 1990-07-03 | 1992-08-04 | Tamfelt Oy Ab | Device for measuring the condition of a felt and for reconditioning it |
| US5349845A (en) * | 1992-04-07 | 1994-09-27 | Tamfelt Oy Ab | Apparatus for measuring the condition of a felt in a paper machine |
| US5964956A (en) * | 1997-06-25 | 1999-10-12 | Voith Sulzer Papiermaschinen Gmbh | Process for cleaning a transport belt |
| US6143092A (en) * | 1997-06-25 | 2000-11-07 | Voith Sulzer Papiermaschinen Gmbh | Process for cleaning a transport belt |
Also Published As
| Publication number | Publication date |
|---|---|
| NZ194626A (en) | 1984-11-09 |
| BR8005192A (en) | 1981-03-04 |
| AU6138380A (en) | 1981-02-19 |
| DE3069420D1 (en) | 1984-11-15 |
| EP0024205B1 (en) | 1984-10-10 |
| FI802545A (en) | 1981-02-17 |
| MX153235A (en) | 1986-08-29 |
| ZA804983B (en) | 1981-08-26 |
| AU536648B2 (en) | 1984-05-17 |
| EP0024205A1 (en) | 1981-02-25 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |