Note: Descriptions are shown in the official language in which they were submitted.
2~80397
~EVICE FOR APPL~CATION OF COATING COLO~
ON A FIBER ~
Tho invention is diract~ to a nozzle ~ypo coating dev$ce
for application Of a Coati~g mixtur~ on a running p~per web.
Cevice~ o~ this type may be arranged wlthin or outside a
paper machine. I~he liguld to ~a ~pplied, e.g., may bQ a 8~ze
suspensi~n ~or ~mpregna~ion o~ tho paper web; l.e., the ~ize
Bu~pen~ on penetr~t~ the int~rlor o~ the paper web mor~ o~ le~
complet~ly. BUt the liquid m~y also be a ~oating ~ixture; me~nt
thareby are pigment ~uspen~ions of mo~t varled type of which ~
finl6h coat i6 ~ormed on th~ paper we~. In both case~, th~ liquid
~ay be applied on only one 6ide or on both sldes of the pap~r
web.
RepresQntativ~ prior art includeo: German utility patent
g 111 669; Ger~an utility p~tont 8 414 413; U.S. Patent No.
2,729,192; U.S. Patent No. 2,946,307; U.S. Patent No.
3,084,663; Woch~nbl3tt f~r Papierfa~rikatlon (Papermaking
Weekly) 1973, pageB 164 through 169; and Wochen~latt ~r
Papier~abrikation (~apermaking We~kly) 1978, pag~s 773 through
778.
~he coating ~uality in ooater~ o~ any ~ype depenas
deci~lvely on all of the event~ occurring along ths entlre p~th
of the coating mixtu~e up to its application on the paper web.
Here, the di~tributlon pipe play~ a dominant role, servlng the
uniform distr~ution of the coating mixtur~ acro3s the wid~h o~
th~ paper ~eb. Thls d~stri~utlon pipe i6 withln th~ coat~r in
horizontal position. It ie on both ~nd~ charged with coating
mlxture ~lows. Ths~e have thus oppo~its direction ~he coati~g
mixture di~charges fro~ ths di~trlbutlo~ plpe via bores which 2re
arrsnged acro~ the length of the d~stribut~on pipe. ~hus, th~
veloclty in s~id c~ating mixture ~1DW~ i~ being diminis~d on the
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~low path, beginning at the respective ond side and endlng in the
center area o~ th- distribution pipe length. W~th proper de~ign,
the two par~ial flows ~hould there~ore come to rest in the center
area.
A decisi~- disturban~e factor is alwaye alr contained ln the
coating mixture. Tbis air must be lim~natea at any rate before
the coatlng mixture reachos the paper web. All sorts of
deaera~lon mea~ures have bBen used for that purpose. InRtalled on
the dlstribution plpe, ~or example, i8 a ~eaeration dome which
xtends acros~ the ntire length of the dlstribution plpe and
communicates with the interlor ~ the di6tributlon p~pe ~ia
~urther ~ores. A small partial flow la~en to a greater degree
with alr bubble~ leaves the distribut1on pipB th~ough the~e bores
and enters the ~aid channel ~or being returned again to the
lS circula~ion.
The illu~trated prlnciple o~ the known di~tributlon pipe ~
problemat$c. For instAnce, it is difflcult to ~ccomplish tha~ the
two pAr~ial ~lows o~ the coating mixture actually roach a
veloclty of zero in the center a~ea. Tha ~eedlnq from both ond~
requlres a oertain equlpment expense. The ~ecirculation rlow
proceeding through th~ deaeratlon doms b-ing ~mall ln size, the
~Qloclty 16 low as well. Thl6 result6 ln deposlts, and at that,
already in the bore6 between distribut~on pipe and deaQrstlon
do~e. ~as~ly, the di~tribu~io~ it~elf is not optimal either, and
~5 at that, due to the ~eloclty ~eduction of the partlal f 10WB on
thQ ~y between th- entrance to the di~trlbution pipe and the
center area of the di~tri~ution plpe length.
The probl~m underlying the present inven~ion iB to ~a~hion
su~h a devlce to the e~fect that the coatin~ substance wlll ~e
maxlmally evenly di~tributed across the length o~ the
di6tribution pipe, ~nd thus a~ro6~ the width o~ the paper web,
that tha deaeration problem w~ll bo solved flawle3sly, that
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d-po-lt6 wlll be avolded and the equipm-nt expen~e will be
rQduc-d.
It is an object of the present invention to provide a
nozzle type coating device having a distribution pipe
featuring on one of its two ends an inlet an don its other
end an outlet. Inserts having bores therein are installed
in the wall of the distribution pipe for allowing coating
mixture to flow therethrough.
In d-tall, tne invention ~ccompli-h~s the following The
eoatlng mlxture i- now pAssed through the entlre length Or th-
d~trlbution plp-, from one end to the other, without any
~tand-till occurring Thu~, the coating ~lxture i- con~tantly in
motlon acro-- th~ entlre pipQ length Th- ~ore alr-lad-n part on
this ~low path - vi-w~d ln a cro~s ~ection through th-
di6tributlon pip- - 16 containcd ~n it~ upper part, and thu~ on
the ide oppo-ite the bore~ For that rea-on ther- i~ no ri~k of
air-lad~n coatlng mixt~r~ proc~edlng through th- bore-
Th-r-fore, a deaeration dome 1B ~-nerally no longar noc~ ry at
all, although it mAy b- provided
Furth-rmore, the conBtructlon expenB- 1B gr-~tly r-duced a~
compared to prlor coating dev~c~ incQ only ~ ingle feed l~ne
i~ provlded now to on- end o~ the d~atrl~utlon plpe
La-tly, the bore dl~m te~- ~ay be ohang-d at any ti~e, thu-
ad~u6ting a1BO the partial a~ount ls-ulng out of the re-pective
bore; for all that i- need~d is ch~nging the inoert~ ~hl- ha~
the adv~ntage th~t th- piFe may ln ~om~ case- b- cylindr~cal,
~ e , have a con-t~nt cros6 ectlon acro6- th- entlr- length or
at least crosc a~ ~6-ntlal part of lt- l-ngth Thi~ ~cilitates
the manufactur- and, thu~, low-rc the manu~acturing cost- B~t
the plpe may al~o be conical ln ~-~lgn
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A preferred embodiment of the invention will be more
fully explained by way of example only, with the aid of the
drawings, in which:
Fig. 1 18 A slde oect1onal vi-w o~ a coatlng d-vlce Or the
pr-~-nt invention;
F~g 2 i- a ~-c~$onal vi-w of the di~tr$bution p1pe
accordlng to Flq. l; And
Fig 3 i- an nlarged sectlonal vi-w tak-n a~ong llne I~I-
III ln Fiq 2
~h- nozzle typ- coatlng devic- lllustrated in F~g
f-ature6 a nozzle spaoe 3 In the running dlrection of tho web,
this nozzle pace is def$ned by an ovQrflow lat 4 and a doslng
61at 5 Coating o~bstance i~ fed to a di6tri~ut~ on plpe 6 The
distrlbu~ion plpe 6 ~as a number of outlet opening~, which are
not illu~trated here and communlcate with a reed channel 7, ~o
that the coat$ng ~ixt~re proceeda through the channel 7 to the
nozzle ~pace 3, ~nd thu~ to the pap-r web 1 Located hal~way in
th~ ~eed channel ar- the ~poiler bars 7 1 producing a
2~ microturbul-nce in the coating mixture A drain channel 8
establi-he6 a conductive connection to an over~low chute 9
Located at the nd of th- w~rking channel 8 16 an adjustable
valve 10 for control o~ the amount of o~errlow A d-vic- 11
erv-s to control the ~lexural co~pen~ation What matt-rs here 1
pecl~ically t~e ~lexur~l co~pansation of tho do~lng 61at 5
However, also t~o ~1QXUre 0~ the ~ntire coatlng device can be
in~luenced
The compen-ation device 11 ~- preoently de6ignsd according
to D~ 39 2S 5~7 A1 It fe~tures a otatlonsry yoke 12, a sleeve 13
surrounding the yoke 12, and pr-06ure trans~er lements 14,
pre-ently air b~llows Charging the air bellows with compressed
alr changes the position o~ the eleeve 13, and thus al~o t~at of
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t~Q dosing slat 5, thereby effectlng a ~ompensa~ion Or flexure.
T~e desl~n and arr2ngement o~ the compQn~tion device 11 mAy be
~uch that a surficlently large "inner stroke" is created for
ad~usting also the width of the qap ~etween thQ edge o~ the
5 dosing slat 5 and t~e paper web 1. Thu~, no further device ~ B
requlred for tha~ purpose. Provldad in the present case i8 a
laser measur~ng devlca 15 for dQterminlng the Qxact po~ltlon of
the edge o~ the dosing ~lat 5. A s~gnal obtained thereby i8 used
for control of th~ compensation device 11.
Details of the dlstrlbu~ion pipe 6 can be soen ~ore exactly
~rom Fig. 2 and 3. The distribution plpe ~ has a cylln~rlcal
shape, and at that, pre6ently ~hat of a circular cylin~er. The
distribution pipe ~ has an entrance end 20 and an exit end 21.
ContalnQd in exit end 21 i5 a con~txiction member 22. Ins~rts 24
are arranqed across the length o~ distribution pipe 6 - inalcated
only 6chematically $n Flg. 2. The flow i8 in the directlon o~
arrow 25.
The cross-se~tional lllustration according to Fig. 3 dep~cts
the inserts 24 more accurat~ly. They ~eature bore~ 25 having a
certain di~meter d. The interior of the distr~butlon pipe 6 ls
extQnsively fil~ed with coating mixture. But there are also alr
bubbles 28 visible, in Flg. 2 and 3, ln the upper area of the
interior space. ~he flow proceeding inventionally from the
entrance end to the exit end, ~ considerable ~eloci~y prevail~
across the entiro length of the di-trlbutlon pipe. A 6tandstill
of ths flow occ~r6 nowhere. ~herefore, also the air bubbles 28
migrate dep~ndably through the sntire di~trlbution pipe. Thcy are
contained - as illustrated in Fig. 3 - alway~ oppo3ite the bores
26, ~o tha~ at an~ rate they canno~ exit with the ooating mixture
througn th~ bores and thu~ not proceed eith~r to the paper web .
The bores 26 in the in3erts 24 dif~er in ~iza from insart ~o
insert. Generally, the dimension d in~r~a~ea ~lowly wlth the
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increaslng ~low, starting from the entrance end 20, up to the
exit ~nd 21. The dl~-n~ion d of tho individual bores can b~
detormlned rather accurately ahead ot tlme by computatlon. The
ob~ectlvo ln this ia to ~a~ion ~he dimen~ion d Or the inoert~ $n
such a way that the ame partlal amoun~ of coatlng mixture will
xit from each bore 26, ao that the coatlng ~ixture will ~
distrlbuted maxlmally unlformly across the length of distr$butlon
plpe 6 and thue aaro~6 the wldth of the paper we~.
In6erts 24 are eaaily exchangeable. For example, insert~ 24
may be fa6tened in the wall of the di6trlbution pipe 6 by
threadlng or clamping with a snap e~fect. Th- meaning Or 1~ 1
this: the rheological behavior of coat1ng ~ixtures differs
qreatly. It ia mostly completely dlfferent ~rom that of water.
~he ~low performance can frequently not be computed xactly.
Therefore, $t ia ultable to ma~e the in~ort~ eaaily
exchangea~le. Then it i8 ea6y to cnange over to bores wlth
di~-r-nt diamet~rs in order to achieve con6tant partial amount~
at all bores.
Pro6ently, diatribution pipe 6, a~ shown in Fig. 3, ha~ a
circ~larly cylindrical shape. But lt may alao have an elliptic
cross a-ction. The longitudinal axls o~ t~e elllpa~s li-s then in
a vertical plane. Thls has th~ ad~antag~ that with a glven croa--
6ectional area of the interior 6pace the tistance between ~he
borea 26, for one, and the opposite point at which the a~r
?5 bu~ble~ flow, for ~nother, $s maximally large, precluding the
r$sk that air bubbles proce~d to the bore3.
