CA1190075A - Apparatus for forming bound-layer sheet of paper - Google Patents
Apparatus for forming bound-layer sheet of paperInfo
- Publication number
- CA1190075A CA1190075A CA000415530A CA415530A CA1190075A CA 1190075 A CA1190075 A CA 1190075A CA 000415530 A CA000415530 A CA 000415530A CA 415530 A CA415530 A CA 415530A CA 1190075 A CA1190075 A CA 1190075A
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- paper
- belt
- forming roll
- layer
- grooves
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Abstract
ABSTRACT OF THE DISCLOSURE:
A bound-layer type Fourdrinier papermaking machine is improved by providing its forming roll on the periphery thereof with circular or helical grooves.
The air entrapped in the wedge-shaped gap between the forming roll and the endless felt belt advanced toward the forming roll is expelled through the grooves, to ensure production of a high-quality sheet of paper at a high speed.
A bound-layer type Fourdrinier papermaking machine is improved by providing its forming roll on the periphery thereof with circular or helical grooves.
The air entrapped in the wedge-shaped gap between the forming roll and the endless felt belt advanced toward the forming roll is expelled through the grooves, to ensure production of a high-quality sheet of paper at a high speed.
Description
~PPARATUS FOR FO~MING BOUND--LAYER S~EET OF PAPER
~ hls inventlorl rel~tes to an appara~us for the 5 formatlon of a bound-layer ~heet of paper.
A~ bound-layer ~heet p~p~rmaklD~ m~chines, the FourdrinlQr machln~ and th~ cylirlder machine ~ncl thelr comblnation~ axa known to the art.. The~ pape~makincJ
m~chlne~ are chi,efly u~ed for tha manuf~cture of whlte 1 O bo~rds and 1 in~r~ D The common requlrements any ~uch paper 1~ expected to fulflll, therefor~, lnclud~ tldy orlentatlon of flber~, excellent :Eormal:lon and unlform thlckn~, small local v~rlatlon o~ paper w~ight~ and ~trong adh~3~ ion b~tween comporlent lay~rs o~ th~ sheet.
15 In vi~w of th~ r~quirements ~ the bound-layer Four~rlnl~r machine proves to be ideal among oth~r typi~s o~ paper-maklng machine~ " Thi~ i~ b~3causs th~ adop~.ion of the Fourdrlnl~r machlne permlt~ th~ ~heet Pormlng speed and the feed1ny ~pe~d of dilu~e flber~water ~lurry to be ~0 ad~u~ted over a falrly wlde range ~nd, therefore, ensure~
formatlon o~ a bound-layer ~heet o~ high quallty, In reallty, how~ve!~r, these papermaking machine~ have be~n u~ed only for tha m~nufacture of high~ grade whlte board~
and very ~01dom ~or the manuieacture o low-priced bc)ard~ O
~5 ~hl~ i~ not mer~ly because ths lnltlal co~t o~ e~uipm~nt ~nd t~le cost of operatlon are hlgh but al80 becau~e the bound~layer sh~!~t produced by ~uch machines hA~ a di~
advan kage in th~at the interl~y~r adhe~ iv~ 8 trength is ~ . J`~ ~
~91(~
rather low.
A Fourdrinier p~permaklng machlne whlch ov~rcom~s th~ drawbacks mentloned abo-/-eF namely, which 1~ capable Ol' forming a hlghly deslrable ~h~et and produclng boar(l~
S of all colors, h~ been propo~d in Japane~e Pa~nt Publication Sho 55~1980~-8640 (JapnnE3~e Patent No~
1,0~9~ 068) O
Thls lnventlon rela~e~ to lmprovement~ in and 10 Concerrling the propo~ed Fourdr~nler papermaking machlr mentioned above~ Speclf~cally~ lt provlde~ an apparatu~
for form~ng a bound^-l~yer 3heet of papex~ whlcll enable~
drainaq~3 of water ~rom th~ layer~ of dllute f iber~wat~r ~lurry to proce~d quickly and ef~lclently~ avold~
15 induclng di~lntegration of pap~r layer~ ~ and produce~
high grade paper layer~.
In the propo$ed Fourdrini~r papermaklng machine m~ntloned above ~ th~re ls pro~ided an endless wir~
æcxeen belt w~hich has a straight portlon used for the 20 fc~rmatlon of a papexmaklng layer ~nd al~o ha~ a fc:rming roll rotatably di~po~ed at the leading end of the ~traight portion~ An endle~s fe~t belt having .~ pre-llmlnarily draln2d papermaklng layex ~herlng to the lower ~urfac6~ thereo~ :Is introduced between th2 afore-25 mentloned ~orming rvll and endle~ wlre ~cr~en belt.While ~he formlng roll i~ rota~ed b~r the endle~s felt belt ancl the endle3s wlre x~r~en belt~. the paper layers one ~ach on the endle~æ wire ~creen b~lt atld the endle~.
-- 2 ~
fel-t bel-t are pressed agains-t the periphery of the ro-ta-ting forming roll. Thus, -the fibers of -the paperma~ing layers are caused -to inter-twine and the wa-ter in the papermaking layers is drained by centrifugal force, with -the result that a bound paper layer is formed. At -the time that -the endless felt bel-t is forwarded and brought in-to contac-t with -the forming roll, the forming roll rota-ting at a high speed entrains air and entraps it between -the forming roll and the fel-t belt, -thus inducing disintegra-tion of -the paper-making layer. To cope wi-th -this disadvantage, -the present invention has groove means formed on the periphery of the aforementioned forming roll. These grooves means permit the aforementioned entrapped air to be expelled when the felt belt is pressed by the endless wire screen belt agains-t the periphery of the forming roll. Consequen-tly, disinte-gration of the papermaking layer is precluded even when the machine is operated at alhigh speed.
More particularly, the present invention provides appa-ratus for the formation of a bound-layer sheet of paper, comprising, a wire screen belt and a felt belt for receiv-ing therebetween a firs-t paper layer upon the wire screen belt and a second paper layer upon a first surface of the felt belt, a forming roll rotatably disposed in contact with a second surface of the fel-t belt, and defining there-with a wedge-shaped gap, for comprefsing -together the first and second paper layers between -the felt belt and the wire screen belt for forma-tion of the bound-layer sheet oE paper, and groove means defined within the outer surface periphery of the forming roll, the groove means having a predetermined spacing or pitch defined be-tween successive grooves as viewed - 3~
in the axial direction of the forming roll for permi-t-ting the escape o:E air entrapped within -the wedge-shaped gap formed between the felt bel-t and the forming roll so as to preven-t the transmission of -the air into the felt belt, -the second paper layer, and the bound-layer sheet of paper, and for simultaneously preven-ting -the transmission of any excess water con-tained within the Eirs-t and second paper layers through -the felt belt and the forming roll whereby the excess water.is expressed outwardly away from the form--ing roll -through the wire screen belt only, when -the bound~
layer sheet of paper is formed as a result of the com-pression together of the firs-t and second paper layers.
The present invention will become more readily apparent from the following disclosure of an embodimen-t of the inven-tion with reference to the accompanying drawings, in wh.ich:
FIG. 1 is a schematic overall s-tructu:ral diagram of an apparatus for the forma-tion of a bound-layer sheet of paper.
FIG. 2 is a schematic diagram of a conven-tional appara~
tus for the formation of a bound-layer sheet of , - 3a -O~d5i paper ~.
FIG~. 3 1~ an enlarged cross~ectlorla:l v:Lew of the es~ent.~al part of an app~ratus embodyil~g -the presentirlvention for the formation of a bound~layer ~heet of p~per~
E~I~. 4 ls ~n enlarg~d p~3~sp~ctiv~ view lliu~tratlng ~he es~ential part of the ~pp~ratu~ embodyin~ -th~ pr~sen-t in~entlon ~or the :~ormatlorl o~ a bound~layer ~h~et of p~per ~, DET~ED DESCRIPTION OF P~EFERRED EMBODIMENT a E~y way of lntroductlony the conventlonal Fcsurc~rlrller papermaking m~cl~ e wlll be de~cr:Lbed wlth reference to FIGD 1 and F:lG. 2~D An ~ndles~ wlre ~creen belt 1 ha~ a ~traight p~per~layer forming zone la ~or forming a papermaklng layer Pl thereorl and ~a~ R form,ing roll ~
15 rotatal:)ïy dl~pos~d at the l~ading end of the paper-layer ~orming xone la. An endle~ felt belt 3 is dl~posecl ~to travel ~ubi3tantlally p~rallelly ~c~r ~ htly obliquely upwardly or downwaxdly~ r~lativ~ to the endle~ wir~
3cr~e~ bel~ l. Thli~ ~ndles~ fe1t belt 3 p to th~ low~3r ~0 ~urace oiF whlch the pap~rmak:Lng ~ayer P2 formed in the s;heetformlng d~rice of the precedlng ~tag~ and prellml~
narily dralned h~ be~3n applled ~ 19 lntroduced b~tween the ~ormlng roll 2 and tha endl~ wlre ~cxeen be1t l.
Con~equently, the ~orming roll 2 ls rota~ced by the 25 endle~ felt belt an~J posslbly~ addl tic~nally by the endle~ wlr~ ~areen belt and, at th~3 ~ama tlm~, the papermaklny layer~ Pl, P~ ar~ ~up~rpo~ed t pinched b~tween the felt helt .l and the wire 3creerl belt 1; and passed q ~
upwardly over about one fourth to one half of the entire periphexy of the forming roll 2. The endless wire screen belt 1, owing to its tension, presses the two papermaking layers Pl, P2 against the periphery of the forming roll 2, or more precisely against the felt belt 3 covering the forming roll 2. By this pressure coupled with the centrifugal fol-ce generated by the rotation of the forming roll 2, the considerable amount of water contained chiefly in the freshly formed papermaking layer Pl is drained through the meshes in the en~less wire screen belt 1. Then, the wire screen belt 1 and the felt belt 3 which have departed from the forming roll 2 are passed over a couch roll 4, with the inner surface of the wire screen belt 1 in direct contact with the couch roll 4. The ~elt belt 3 to the lower surface of which the two paperma~ing layers P'2 (Pl ~ P2) have been transferred is forwarded to a press part P or to the forming roll in the subsequent papermaking device.
The wire screen belt 1 is returned back to the straight paper-layer forming zone la.
In this machine, the centrifugal force of the forming roll 2 increases and the efficiency of removal of water ~rom the papermaking layers is enhanced in proportion as the sheet forming speed increases.
Further since -the application of pressure to the paper-making layers and the drainage of water from these la~ers continues throughout the period during which the wire screen belt 1 and the felt belt 3 travel around the ~90~:~7~
forming roll and consequently keep the forming roll in rotation, the fibers of the two papermaking layers Pl, P2 are intertwined fast along their i~terface and the paper which is produced as these papermaking layers are dried by being passed through the press part and the dry part does not su~fer from layer separation. This machine features these and other merits.
The actual operation of this machine, however, has revealed the following problems. Since the forming roll
~ hls inventlorl rel~tes to an appara~us for the 5 formatlon of a bound-layer ~heet of paper.
A~ bound-layer ~heet p~p~rmaklD~ m~chines, the FourdrinlQr machln~ and th~ cylirlder machine ~ncl thelr comblnation~ axa known to the art.. The~ pape~makincJ
m~chlne~ are chi,efly u~ed for tha manuf~cture of whlte 1 O bo~rds and 1 in~r~ D The common requlrements any ~uch paper 1~ expected to fulflll, therefor~, lnclud~ tldy orlentatlon of flber~, excellent :Eormal:lon and unlform thlckn~, small local v~rlatlon o~ paper w~ight~ and ~trong adh~3~ ion b~tween comporlent lay~rs o~ th~ sheet.
15 In vi~w of th~ r~quirements ~ the bound-layer Four~rlnl~r machine proves to be ideal among oth~r typi~s o~ paper-maklng machine~ " Thi~ i~ b~3causs th~ adop~.ion of the Fourdrlnl~r machlne permlt~ th~ ~heet Pormlng speed and the feed1ny ~pe~d of dilu~e flber~water ~lurry to be ~0 ad~u~ted over a falrly wlde range ~nd, therefore, ensure~
formatlon o~ a bound-layer ~heet o~ high quallty, In reallty, how~ve!~r, these papermaking machine~ have be~n u~ed only for tha m~nufacture of high~ grade whlte board~
and very ~01dom ~or the manuieacture o low-priced bc)ard~ O
~5 ~hl~ i~ not mer~ly because ths lnltlal co~t o~ e~uipm~nt ~nd t~le cost of operatlon are hlgh but al80 becau~e the bound~layer sh~!~t produced by ~uch machines hA~ a di~
advan kage in th~at the interl~y~r adhe~ iv~ 8 trength is ~ . J`~ ~
~91(~
rather low.
A Fourdrinier p~permaklng machlne whlch ov~rcom~s th~ drawbacks mentloned abo-/-eF namely, which 1~ capable Ol' forming a hlghly deslrable ~h~et and produclng boar(l~
S of all colors, h~ been propo~d in Japane~e Pa~nt Publication Sho 55~1980~-8640 (JapnnE3~e Patent No~
1,0~9~ 068) O
Thls lnventlon rela~e~ to lmprovement~ in and 10 Concerrling the propo~ed Fourdr~nler papermaking machlr mentioned above~ Speclf~cally~ lt provlde~ an apparatu~
for form~ng a bound^-l~yer 3heet of papex~ whlcll enable~
drainaq~3 of water ~rom th~ layer~ of dllute f iber~wat~r ~lurry to proce~d quickly and ef~lclently~ avold~
15 induclng di~lntegration of pap~r layer~ ~ and produce~
high grade paper layer~.
In the propo$ed Fourdrini~r papermaklng machine m~ntloned above ~ th~re ls pro~ided an endless wir~
æcxeen belt w~hich has a straight portlon used for the 20 fc~rmatlon of a papexmaklng layer ~nd al~o ha~ a fc:rming roll rotatably di~po~ed at the leading end of the ~traight portion~ An endle~s fe~t belt having .~ pre-llmlnarily draln2d papermaklng layex ~herlng to the lower ~urfac6~ thereo~ :Is introduced between th2 afore-25 mentloned ~orming rvll and endle~ wlre ~cr~en belt.While ~he formlng roll i~ rota~ed b~r the endle~s felt belt ancl the endle3s wlre x~r~en belt~. the paper layers one ~ach on the endle~æ wire ~creen b~lt atld the endle~.
-- 2 ~
fel-t bel-t are pressed agains-t the periphery of the ro-ta-ting forming roll. Thus, -the fibers of -the paperma~ing layers are caused -to inter-twine and the wa-ter in the papermaking layers is drained by centrifugal force, with -the result that a bound paper layer is formed. At -the time that -the endless felt bel-t is forwarded and brought in-to contac-t with -the forming roll, the forming roll rota-ting at a high speed entrains air and entraps it between -the forming roll and the fel-t belt, -thus inducing disintegra-tion of -the paper-making layer. To cope wi-th -this disadvantage, -the present invention has groove means formed on the periphery of the aforementioned forming roll. These grooves means permit the aforementioned entrapped air to be expelled when the felt belt is pressed by the endless wire screen belt agains-t the periphery of the forming roll. Consequen-tly, disinte-gration of the papermaking layer is precluded even when the machine is operated at alhigh speed.
More particularly, the present invention provides appa-ratus for the formation of a bound-layer sheet of paper, comprising, a wire screen belt and a felt belt for receiv-ing therebetween a firs-t paper layer upon the wire screen belt and a second paper layer upon a first surface of the felt belt, a forming roll rotatably disposed in contact with a second surface of the fel-t belt, and defining there-with a wedge-shaped gap, for comprefsing -together the first and second paper layers between -the felt belt and the wire screen belt for forma-tion of the bound-layer sheet oE paper, and groove means defined within the outer surface periphery of the forming roll, the groove means having a predetermined spacing or pitch defined be-tween successive grooves as viewed - 3~
in the axial direction of the forming roll for permi-t-ting the escape o:E air entrapped within -the wedge-shaped gap formed between the felt bel-t and the forming roll so as to preven-t the transmission of -the air into the felt belt, -the second paper layer, and the bound-layer sheet of paper, and for simultaneously preven-ting -the transmission of any excess water con-tained within the Eirs-t and second paper layers through -the felt belt and the forming roll whereby the excess water.is expressed outwardly away from the form--ing roll -through the wire screen belt only, when -the bound~
layer sheet of paper is formed as a result of the com-pression together of the firs-t and second paper layers.
The present invention will become more readily apparent from the following disclosure of an embodimen-t of the inven-tion with reference to the accompanying drawings, in wh.ich:
FIG. 1 is a schematic overall s-tructu:ral diagram of an apparatus for the forma-tion of a bound-layer sheet of paper.
FIG. 2 is a schematic diagram of a conven-tional appara~
tus for the formation of a bound-layer sheet of , - 3a -O~d5i paper ~.
FIG~. 3 1~ an enlarged cross~ectlorla:l v:Lew of the es~ent.~al part of an app~ratus embodyil~g -the presentirlvention for the formation of a bound~layer ~heet of p~per~
E~I~. 4 ls ~n enlarg~d p~3~sp~ctiv~ view lliu~tratlng ~he es~ential part of the ~pp~ratu~ embodyin~ -th~ pr~sen-t in~entlon ~or the :~ormatlorl o~ a bound~layer ~h~et of p~per ~, DET~ED DESCRIPTION OF P~EFERRED EMBODIMENT a E~y way of lntroductlony the conventlonal Fcsurc~rlrller papermaking m~cl~ e wlll be de~cr:Lbed wlth reference to FIGD 1 and F:lG. 2~D An ~ndles~ wlre ~creen belt 1 ha~ a ~traight p~per~layer forming zone la ~or forming a papermaklng layer Pl thereorl and ~a~ R form,ing roll ~
15 rotatal:)ïy dl~pos~d at the l~ading end of the paper-layer ~orming xone la. An endle~ felt belt 3 is dl~posecl ~to travel ~ubi3tantlally p~rallelly ~c~r ~ htly obliquely upwardly or downwaxdly~ r~lativ~ to the endle~ wir~
3cr~e~ bel~ l. Thli~ ~ndles~ fe1t belt 3 p to th~ low~3r ~0 ~urace oiF whlch the pap~rmak:Lng ~ayer P2 formed in the s;heetformlng d~rice of the precedlng ~tag~ and prellml~
narily dralned h~ be~3n applled ~ 19 lntroduced b~tween the ~ormlng roll 2 and tha endl~ wlre ~cxeen be1t l.
Con~equently, the ~orming roll 2 ls rota~ced by the 25 endle~ felt belt an~J posslbly~ addl tic~nally by the endle~ wlr~ ~areen belt and, at th~3 ~ama tlm~, the papermaklny layer~ Pl, P~ ar~ ~up~rpo~ed t pinched b~tween the felt helt .l and the wire 3creerl belt 1; and passed q ~
upwardly over about one fourth to one half of the entire periphexy of the forming roll 2. The endless wire screen belt 1, owing to its tension, presses the two papermaking layers Pl, P2 against the periphery of the forming roll 2, or more precisely against the felt belt 3 covering the forming roll 2. By this pressure coupled with the centrifugal fol-ce generated by the rotation of the forming roll 2, the considerable amount of water contained chiefly in the freshly formed papermaking layer Pl is drained through the meshes in the en~less wire screen belt 1. Then, the wire screen belt 1 and the felt belt 3 which have departed from the forming roll 2 are passed over a couch roll 4, with the inner surface of the wire screen belt 1 in direct contact with the couch roll 4. The ~elt belt 3 to the lower surface of which the two paperma~ing layers P'2 (Pl ~ P2) have been transferred is forwarded to a press part P or to the forming roll in the subsequent papermaking device.
The wire screen belt 1 is returned back to the straight paper-layer forming zone la.
In this machine, the centrifugal force of the forming roll 2 increases and the efficiency of removal of water ~rom the papermaking layers is enhanced in proportion as the sheet forming speed increases.
Further since -the application of pressure to the paper-making layers and the drainage of water from these la~ers continues throughout the period during which the wire screen belt 1 and the felt belt 3 travel around the ~90~:~7~
forming roll and consequently keep the forming roll in rotation, the fibers of the two papermaking layers Pl, P2 are intertwined fast along their i~terface and the paper which is produced as these papermaking layers are dried by being passed through the press part and the dry part does not su~fer from layer separation. This machine features these and other merits.
The actual operation of this machine, however, has revealed the following problems. Since the forming roll
2 is a smooth roll or plane roll having a cylindrical surface as its periphery, air is captured in a wedge-shaped gap 6 formed between the felt belt and the forming roll 2 at the time that the felt belt advancin~ toward the forming roll comés into contact with the forming ~ roll/ and the entrapped air, unable to find a way out, is lodged within the felt belt. At the time that the wire screen belt l with its own tension presses the two papermaking layers Pl, P2 against the periphery of the forming roll, this lodged air is forced out of the felt belt and transferred into the papermaking layer P2.
Consequently, the air leaves its mark in the bound-layer wet sheet and induces the so-called phenomenon o~ dis-integration of sheet. The produced paper, therefore, suf~ers from impaired quality.
In an effort to overcome this drawback, the inventors have trially constructed a forming roll by stretching a net round the periphery of a cylinder cell so as to expe:L the entrapped air through the meshes of the net into the interior of the roll. Although this arrangemen-t succeecled in precluding disintegration of sheet, it has a disadvan-tage in that part oE the water in the papermaking layers which ought to be expelled outwardly by the centrifugal force of the forming roll is absorbed by the felt and is gradually accumulated inside the roll to the e~tent of impairing the efficiency of water removal. When the sheet forming speed is low, the water which has thus accumulated within the roll ma~
be discharged in the axial direction from the opposite ends of the roll. When the speed is high, such discharge of the water cannot be obtained. This accumulation of water, therefore, deprives the device of its characteris-tic feature, namely that the efficiency of water removal increases with the increasing sheet forming speed. Thus, the device must be operated at a low speed~ When the plane of the felt belt tangent to the peripher~ of the forming roll forms a small angle with the horizon, the water contained in the roll is forced out into the wedge-shaped gap between the felt belt and the forming roll andabsorbed in the felt belt before the felt belt comes into contact with the roll. At the time that the wire screen belt with its own tension presses the papermaking la~ers Pl, P2 and the felt belt against the periphery of the Eorming roll, the water is squeezed out of the felt belt and transferred into the papermaking layer P2. Thus, disintegration of sheet is brought about not by air but by the water forced out of the felt belt. Moreover, because oE its peculiar construction, the roll having a net stretched round the periphery thereof can not be easily formed with perfect circularity o-f shape. Thus, the device suffers from poor dimensional accuracy and the net must be replaced after a certain length of operation. The price of this device is notably high as compared with that of a roll made of a steel tube.
The inventors, therefore, have made a diligent study in search of a measure which retains the charac-teristic features of the conventional machine intactand, at the same time, precludes the entrapment of air in the wedge-shaped gap 6 between the felt belt and the forming roll. They have consequently ascertained that when the forming roll is provided on the periphery thereof with circular or helical grooves, disintegration of sheet is precluded and the air entrapped is smoothly expelled. _ The grooves 5 thus formed on the periphery of the forming roll 2 fulfill their function fully when they have a depth of 2 to 3 mm and a width of 1 to 3 mm.
When these grooves 5 are formed in a circular shape, they may be spaced in the axial direction of the roll at intervals of about 2 to 3 mm. When they are formed in a helical shape, they may be formed with a pitch equalling the interval.
When grooves 5 are formed circularly or helically on the periphery of the forming roll 2 in accordance with this invention, the entrapped air is allowed to escape through these grooves 5 at the time tha-t the felt belt 3 is pressed by the wire screen belt against the periphery of the forming rollO The felt belt 3, there-fore, does not en-train any air and disintegration of papermaking layers due to the entrapped air can no longer occur. Since the grooves have a narrow width as mentioned above, the water contained in the two papermaking layers is hardly allowed to enter the grooves at the -time that the felt belt is pressed against the periphery of the forming roll. Thus, the provision of these grooves results in substantially no degradation of the efficiency of removal of water from the papermaking layers.
The forming roll is made of a steel tube or stainless steel tw~e 0.7 to 1.8 m in outside diameter. Optionally, the steel tube may be covered with a layer 7 of rubber 10 to 20 mm in thickness~ The grooves may be Eormed on the periphery of the roll by the use of a lathe. The grooves~
therefore, can be formed easily at a rather low cost.
As is clear from the ~oregoing description, this invention improves the bound-la~er Fourdrinier papermaking machine by the provision of circular or helical grooves on the periphery of the forming roll. Owing to this improvement, disintegration of papermaking layers is no longer suffered even when the machine is operated at a high speed and the papermaking layers are bound with ample adhesive strength to afford high-qualit,y paper. The improved machine offered by this invention can be used for the manu~acture of not only high~grade white boards but also boards of ordinary grade.
g
Consequently, the air leaves its mark in the bound-layer wet sheet and induces the so-called phenomenon o~ dis-integration of sheet. The produced paper, therefore, suf~ers from impaired quality.
In an effort to overcome this drawback, the inventors have trially constructed a forming roll by stretching a net round the periphery of a cylinder cell so as to expe:L the entrapped air through the meshes of the net into the interior of the roll. Although this arrangemen-t succeecled in precluding disintegration of sheet, it has a disadvan-tage in that part oE the water in the papermaking layers which ought to be expelled outwardly by the centrifugal force of the forming roll is absorbed by the felt and is gradually accumulated inside the roll to the e~tent of impairing the efficiency of water removal. When the sheet forming speed is low, the water which has thus accumulated within the roll ma~
be discharged in the axial direction from the opposite ends of the roll. When the speed is high, such discharge of the water cannot be obtained. This accumulation of water, therefore, deprives the device of its characteris-tic feature, namely that the efficiency of water removal increases with the increasing sheet forming speed. Thus, the device must be operated at a low speed~ When the plane of the felt belt tangent to the peripher~ of the forming roll forms a small angle with the horizon, the water contained in the roll is forced out into the wedge-shaped gap between the felt belt and the forming roll andabsorbed in the felt belt before the felt belt comes into contact with the roll. At the time that the wire screen belt with its own tension presses the papermaking la~ers Pl, P2 and the felt belt against the periphery of the Eorming roll, the water is squeezed out of the felt belt and transferred into the papermaking layer P2. Thus, disintegration of sheet is brought about not by air but by the water forced out of the felt belt. Moreover, because oE its peculiar construction, the roll having a net stretched round the periphery thereof can not be easily formed with perfect circularity o-f shape. Thus, the device suffers from poor dimensional accuracy and the net must be replaced after a certain length of operation. The price of this device is notably high as compared with that of a roll made of a steel tube.
The inventors, therefore, have made a diligent study in search of a measure which retains the charac-teristic features of the conventional machine intactand, at the same time, precludes the entrapment of air in the wedge-shaped gap 6 between the felt belt and the forming roll. They have consequently ascertained that when the forming roll is provided on the periphery thereof with circular or helical grooves, disintegration of sheet is precluded and the air entrapped is smoothly expelled. _ The grooves 5 thus formed on the periphery of the forming roll 2 fulfill their function fully when they have a depth of 2 to 3 mm and a width of 1 to 3 mm.
When these grooves 5 are formed in a circular shape, they may be spaced in the axial direction of the roll at intervals of about 2 to 3 mm. When they are formed in a helical shape, they may be formed with a pitch equalling the interval.
When grooves 5 are formed circularly or helically on the periphery of the forming roll 2 in accordance with this invention, the entrapped air is allowed to escape through these grooves 5 at the time tha-t the felt belt 3 is pressed by the wire screen belt against the periphery of the forming rollO The felt belt 3, there-fore, does not en-train any air and disintegration of papermaking layers due to the entrapped air can no longer occur. Since the grooves have a narrow width as mentioned above, the water contained in the two papermaking layers is hardly allowed to enter the grooves at the -time that the felt belt is pressed against the periphery of the forming roll. Thus, the provision of these grooves results in substantially no degradation of the efficiency of removal of water from the papermaking layers.
The forming roll is made of a steel tube or stainless steel tw~e 0.7 to 1.8 m in outside diameter. Optionally, the steel tube may be covered with a layer 7 of rubber 10 to 20 mm in thickness~ The grooves may be Eormed on the periphery of the roll by the use of a lathe. The grooves~
therefore, can be formed easily at a rather low cost.
As is clear from the ~oregoing description, this invention improves the bound-la~er Fourdrinier papermaking machine by the provision of circular or helical grooves on the periphery of the forming roll. Owing to this improvement, disintegration of papermaking layers is no longer suffered even when the machine is operated at a high speed and the papermaking layers are bound with ample adhesive strength to afford high-qualit,y paper. The improved machine offered by this invention can be used for the manu~acture of not only high~grade white boards but also boards of ordinary grade.
g
Claims (10)
1. Apparatus for the formation of a bound-layer sheet of paper, comprising:
a wire screen belt and a felt belt for receiving there-between a first paper layer upon said wire screen belt and a second paper layer upon a first surface of said felt belt;
a forming roll rotatably disposed in contact with a second surface of said felt belt, and defining therewith a wedge-shaped gap, for compressing together said first and second paper layers between said felt belt and said wire screen belt for formation of said bound-layer sheet of paper; and groove means defined within the outer surface periphery of said forming roll, said groove means having a predetermin-ed spacing or pitch defined between successive grooves as viewed in the axial direction of said forming roll for per-mitting the escape of air entrapped within said wedge-shaped gap formed between said felt belt and said forming roll so as to prevent the transmission of said air into said felt belt, said second paper layer, and said bound-layer sheet of paper, and for simultaneously preventing the trans-mission of any excess water contained within said first and second paper layers through said felt belt and said forming roll whereby said excess water is expressed out-wardly away from said forming roll through said wire screen belt only, when said bound-layer sheet of paper is formed as a result of said compression together of said first and second paper layers.
a wire screen belt and a felt belt for receiving there-between a first paper layer upon said wire screen belt and a second paper layer upon a first surface of said felt belt;
a forming roll rotatably disposed in contact with a second surface of said felt belt, and defining therewith a wedge-shaped gap, for compressing together said first and second paper layers between said felt belt and said wire screen belt for formation of said bound-layer sheet of paper; and groove means defined within the outer surface periphery of said forming roll, said groove means having a predetermin-ed spacing or pitch defined between successive grooves as viewed in the axial direction of said forming roll for per-mitting the escape of air entrapped within said wedge-shaped gap formed between said felt belt and said forming roll so as to prevent the transmission of said air into said felt belt, said second paper layer, and said bound-layer sheet of paper, and for simultaneously preventing the trans-mission of any excess water contained within said first and second paper layers through said felt belt and said forming roll whereby said excess water is expressed out-wardly away from said forming roll through said wire screen belt only, when said bound-layer sheet of paper is formed as a result of said compression together of said first and second paper layers.
2. The apparatus according to claim 1, wherein said forming roll comprises a steel tube and said grooves are formed on the periphery of said steel tube.
3. The apparatus according to claim 1, wherein said forming roll comprises a steel tube and a layer of rubber deposited on the periphery of said steel tube and said grooves are formed on the periphery of said layer of rubber.
4. The apparatus according to claim 1, wherein said grooves are a multiplicity of circular grooves.
5. The apparatus according to claim 1, wherein said grooves are in a helical form.
6. Apparatus as set forth in Claim 4, wherein:
said circular grooves are spaced apart a distance with-in the range of 1-3 mm.
said circular grooves are spaced apart a distance with-in the range of 1-3 mm.
7. Apparatus as set forth in Claim 5, wherein.
said helical grooves have a pitch within the range of 1-3 mm.
said helical grooves have a pitch within the range of 1-3 mm.
8. Apparatus as set forth in Claim 1, 2 or 3, wherein:
said wire screen belt is an endless belt.
said wire screen belt is an endless belt.
9. Apparatus as set forth in Claim 1, 2 or 3, where-in:
said felt belt is an endless belt.
said felt belt is an endless belt.
10. Apparatus as set forth in Claim 1, 2 or 3, where-in:
the depth of said groove means is within the range of 2-3 mm.
the depth of said groove means is within the range of 2-3 mm.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP170709/81 | 1981-11-18 | ||
| JP17070981U JPS6031120Y2 (en) | 1981-11-18 | 1981-11-18 | Combined paper machine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1190075A true CA1190075A (en) | 1985-07-09 |
Family
ID=15909940
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000415530A Expired CA1190075A (en) | 1981-11-18 | 1982-11-15 | Apparatus for forming bound-layer sheet of paper |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS6031120Y2 (en) |
| CA (1) | CA1190075A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105714591A (en) * | 2014-12-17 | 2016-06-29 | 维美德技术有限公司 | Fiber web machine forming section and secondary forming unit of multilayer forming section |
-
1981
- 1981-11-18 JP JP17070981U patent/JPS6031120Y2/en not_active Expired
-
1982
- 1982-11-15 CA CA000415530A patent/CA1190075A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105714591A (en) * | 2014-12-17 | 2016-06-29 | 维美德技术有限公司 | Fiber web machine forming section and secondary forming unit of multilayer forming section |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6031120Y2 (en) | 1985-09-18 |
| JPS5875800U (en) | 1983-05-21 |
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| MKEC | Expiry (correction) | ||
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