Note: Descriptions are shown in the official language in which they were submitted.
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S P E C I F I ~ A T I O N
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T I T L B
"MAT CWERBD ROLL CONSTRUCIION"
FI}~nl~ OF THE It~r~NTION
This invention relates to the art of covered rolls and
roll covers and particularly deals with resin impregnated mat
covered rolls for papermaking machinery capable of operat$ng at
high speeds under heavy nip loads while maintaining a uniformly
dense finished ~urface.
PRIOR ART
In the process of manufacturing paper, especially
coated and glossy grades of paper, it has been found advantageous
to use a reinforced resin composlte roll cover. These covers are
subjected to extremely harsh treatment in high speed, high nip
loads, 91088 coating and super calendering operations which often
develop high temperatures. Heretofore such composite roll covers
were formed from a thick needled, nonrwoven fibrous mat or
blanket. The mat was coated with a thermosetting resin, wrapped
around the core of the roll, heat treated to thermoset the resin,
20 and machined to present the finished roll surface. The needling
of the thick ~at was required to provide penetration of the
resin, but this operation al80 increased the density of the
fibers around the needled holes. The resulting finished roll
cover had alternating resin rich and mat rich zones which abrade
and wear at Bifferent rates, developing alternating high and low
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areas on the roll face and translating into high and low pressure
areas in the nip. As as result the sheet of paper being treated
soon became marked and when this condition arose, the roll had to
be taken out of ~ervice and redreJsed to dcvelop a smooth uniform
surface. This reconditioning of the roll was very costly and
al~o required down time of the paper machine to accommodate roll
replacements. Further, small air pockets were trapped ln the
resin r~ch areas of the mat. These air pockets tended to get
filled with foreign materials which also marked the paper. The
10 high den~ity a~eas of the needlea fabrlc were difficult to
saturate with the resin often resulting ln voids contributing to
the marking of the paper sheet.
It would then be an improvement in this art to provide
reinforced resin covered rolls free from the heretofore
encountered deficiencie6.
F;UMMARY OF THIS INVENTION
According to this invention there are now provided
reinforced resin covered rolls having a rigid metal core spirally
wrapped with a ribbon or strip of resln coated very thin, light
welght non-woven fibrous material in such a manner as to
eliminate air pockets, and roll surface zones of different
propertie~. The rolls of this invention eliminate or at least
minimize heretofore encountered alternating roll surface zones
which abrade or wear at different rates resulting in alternating
high and low areas on th- roll face and development of high and
low pressure areas ln the nip when the roll is used ln pressure
rolation with nother roll as in calendering operation~ on paper
webs. The flbrous web mat providing the re$nforcement for the
re-ln 1~ not needled, has a very uniform texture, and is
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sufficiently thin and l~ght in weight B0 that the re6~n coatingboth faces of the web i~ not sufficiently separated to develop
alternate web and resin bands on tbe circumference of the roll.
Preferred fabrics for the cover are non-woven, non-
needled, mats of acrylic fibers, polye6ter fibers, ar~mid fibers,
carbon fiber~, or blends of these fibers having a basis we~ght of
between .5 oz/yd2 to 2.0 o~ yd2 and a gauge or thickness of
between .005 lnches to .020 inche~.
~ he preferred resins are of the thermosetting type such
10 as polye-ter resin-, partlcularly epoxy resin~ applied in liquid
form. Suitable oommercial grades of epoxy resins prefer~bly have
an epoxide equivalent weight of 100 to 200. The epoxides are
prepaired in many way~ such as by reacting phenol and acetone and
polyamide~ or other curlng agents are reacted with the epoxy
intermediate.
The fibrous mat 1- formed into a continuous ribbon of a
de~ired width, uch as for exampl- 3 to 6 inches, is coated on
both faces and penetrated with the resin and is spirally wound
wlth lead angle of about 2 to 3 degrees under a tension load of
20 aboot 10 lb~. per inch width around the of the roll with the
edges overlapped a desired amount, ruch as for exa~ple, 1-1/2 to
2- V2~inches. Successive layers of the spirally wrapped ribbon
~-re~-pplled in such a manner that the overlappings are axially
~ ~ di~pl;aced from the overlaps of the ad~acent layers. As the
;~ ~ rlbbon i- applied to the roll, a doctor bar or blade presses it
tightly again-t the underlying surface, ~queezing out excess
fluld r--ln from the coatlng and forming a cylindrical surface of
~; the ~ame diameter cro-~ the entire length of the roll. The
; overlap~ of the ucce~slve layers are preferably axially 60
30~ dl~pl-ced to lie ln lde-br ide rela~ion closlng up any zones
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which might otherwi~e produce air gaps or bubbles. Since the
ribbon i9 80 thin it wlll readily conform to the underlylng
surf~ce.
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After a ae~ired number of layers have been applied to
produce t~icknesses of about 5/8 to 7/R lnch, the wound roll is
heated to ther~oset the resin and the thermoset cover ls then
machined and polished to proauce the deslred finished roll
surface. About 1/8 to 1/4 lnch of thicknes6 i6 removed in the
surface finish$ng operatlon.
Alternately the resin coated ribbon may be wound
edgewise, preferably lncllned, ln a single ~piral wrapping around
the roll eore with a lead of about 5/8~ per revolution. Since
the ribbon i8 80 thin alternating resin rich and mat rich bands
on the circumference will be eliminated because the coatings on
both faces of the ribbon are so close together and the resin
penetr~tes the thin mat. The thickness of the roll of the cover
formed by the ~ingle path edgewise wrapping can be controlled by
th- width of the ribbon and the angle at whieh the ribbon
~ pro~eets from the eore.
The roll eoré ean have a diameter of about 1~ to 40
inches and a length of about 100 to 400 inches.
:
~ It is then an ob~ect of thi6 invention to produce
reinforced re~in eoated rolls substantlally free from mat rich
and re~in rieh surface bands an~ espeeially suited for
;; ~ paper aklng maohinery.
Another ob~ect of this invention is to provide resin
:
lmpregnat-d flber m~t eovers foF rolls whleh have a hard surface
that wear~ at the ~ame rate along its entlre eircumference and
aoeo-s ltB entire length and is eapable of withstanding heavy
~ 30 loads, hlgh ~peed-, and elevated temperatures.
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A ~peclfic object of the invent~on 18 to provide
sp~rally wound thin flbrous belt covered resin coated rolls for
papermaking machinery free from ~ir pockets, altern~tlng re~in
r~ch ~nd f~ber rlch b~nd areas which wear at different rate~
during operation of the roll and havlng a smooth, uniform
s urface.
~ nother specific ob~ect of this lnventlon i8 to provide
a belt covered roll for papermaking machinery formed from very
thin belt materlal.
- Other and further ob~ects of thl~ lnventlon will become
apparent to those skilled ln this art from tbe following detailed
descriptlon of the annexed sheet of drawlng6, which ~how best
mode examples of the invention.
ON THE DRAWINGS .
FIG. l is a schematlc perspectlve view of a pressure
nlp forming palr of rolls having a flber web reinforced re~in
cover on the upper roll ln accordance with thls lnventions
FIG. 2 18 a schematlc side view illustrating the manner
ln which the upper roll of FIG. l is wrapped;
:
FIG. 3 ls a schematic plon view illustratlng the spiral ~:
wrapplng of overiying layer6 on the rolls
~:;
FIG. ~ 18 a tran~versc cros~-sectlonal view along the
llne IV-rV of FIG. 3~
FIG. 5 18 a fragmentary longitudlnal crQss-sectional
view along the llne V'V of FIG. ~, but greatly enl~rged to ~how
and exaggerate the overlap~s
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FIG 6 iQ a schematlc pl~n view with part~ ln 6ection
~howing an alternative wrapping for the roll6 of th$s lnvention
_ FIG.7 1~ a vlew s~mllar to FIG. 5, but ~howing a
modifled covcred roll
AS BHOWN ON THE DRAWING~
.
In FIG. 1 the reference numeral 10 designates in
general a bottom ~etal roll 11 and a top belt or mat covered roll
12 forming nip N therebetween for receivlng sheet materlal,
uch as paper therethrough, to exert a squeezlng action
10 thereon The roll 11 18 formed of a hard material, ~uch as
steel, and i8 8upportea on shafts 13 which are rotatably mounted
ln suitable bearings (not shown).
Tbe upper roll 12 has a cylindrical hard metal, such as
~teel, core 14 with pro~ecting axles 1~ rotatably 6upported in
bearings (not shown) which are shlftably mounted to create a
d-slr-d nip load at N. The ~teel roll cor~ 8 wrapped with
the cover 16 of thi~ invention. The cover 16 presents a ~mooth
uniform contlnuou~ cylindrical surface of the s~me diameter
acros- thé entire length of the roll which can directly engage a
20 face of the paper web pas~ing through the nip N to finish treat
thl- -urface proviaing a glossy or calendered finlsh thereto
Th oover 16 for the roll 12 may be formed a8
ll~ustrated ~n F~G. 2 from a ribbon 17 of non-needled, non-woven
flbrou- materlal as described abovc, whlch 1~ unwound from a feed
roll 18 -nd fed around guldc rolla 19 through a bath 20 of liquia
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re-ln materl~l al-o descrlbed above oontained in an open top tank
21. The re-in ooats both faces of the r~bbon 17 and the ooated
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ribbon is fed between squeeze rolls 22 as it emerges from the
tank 21 to press the resin into the fiber. The squeeze coated
ribbon is then spirally wound around the roll core 14 and a
doctor blade or bar 23 presses the ribbon tightly against the
underlying surface as it is being wound thereby squeezing out
excess resin into a pan and forming a true cylindrical surface on
the core free from undulations. The resin content of the applied
ribbon may be controlled to form from 60 to 95 % of the weight of
the finished cover.
As shown in FIGS. 3 to 5 the ribbon 17 is advanced
along the length of the core 14 in inclined relation to the axis
of the core to provide spiral wrappings in a plurality of layers,
broken away, and illustrated at 24-27. Each layer has adjoining
edges of the ribbon overlapped as illustrated at 28. The amount
of overlap can vary as described above. Any number of successive
layers can be applied to produce the desired thickness for the
cover 16.
Instead of being wrapped flatwise around the core 14,
the ribbon 17 can be wrapped edgewise around the core as
:
20 illustrated in FIG. 6. As there shown, the ribbon is addressed
- ~ ~ edgewise to the core at an angle from the axis of the core and is
^ wrapped in one path from one end to the other end of the core.
This, produces a cover 16a with a circumference composed of the
outer end edges of the ribbon. Since, as explained above, the
ribbon 17 is so thin, the coatings on the faces of this ribbon
will be so close together and the resin will so penetrate the mat
that the circumference of the roll cover is substantially a
continuous resin surface. The wound roll of FIG. 6 is heat
treated to thermoset the resin, and is then machined and polished
30 to form the continuous roll surface. The thickness of the cover
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16a can be controlled by the width ~f the rlbbon, the degree of
angulat~on in wh~ch lt i~ applled to the core and, of cour~e, the
amount of cover material that i~ mach~ned off of the surface.
The cover ha~ ~ unifonm den~ity and can be provlded in
various degree~ of hardness such as 90 to 95 durometer on the ~D~
scale. 8ecause the mat i8 iB 80 very thin it wlll conform
readily to the underlying surface and ~ince the overlap areas
will only produce very thin bands, the finished roll 6urface will
have a constant diameter along lts entlre length. Further, the
Ooverlapping p~ttern of ~ucce~sive layers in the embodiment
lllustrated ln FIGæ. 2 to 5 18 such as to produce the overl~ps in
slde-by-slde relatlon on succes~ive layers thus adding up to a
uniform thickne6s in the flnished wrapping.
~ n high ~peed, high nip load operatlons, the
temperature of the cover may often exceed 250 degrees F and the~e
temperatures may vary across the face width of the roll. Even
under such extreme temperature conditions the covers of thl~
lnvention will maintain their original 6mooth uniform 6urface.
8urface speeds may also exceed 6000 feet per minute at
20 nip loads which exceed 2500 pounds per linear inch of roll face
lnch. The covers of this inventlon wear very well, even under
such extreme conditions.
As lllustrated ln FIG. 7 the roll cover 16 may be used
as a base for a pla~tic cover 30 such as polyurethane. Thi~
plastlc cover oan be grooved clrcumferentlally as illustrated at
31 for use ln a wet pre~s. The cover will have a thickness
varylng from less than to more than the thlckne66 of the cover 16
and may be lntegrally anchored to the cover 16 during the
thermosettlng tep which ~et~ the resln coating on the mat.
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From the above descriptions lt will be therefore
under~tood to those ~killed ln this art that this invention now
provides fibrou~ belt or mat reinforced plastic covered paper
machlne roll~ free fro~ defect~ heretofore encountered in belt
wrapped roll~.
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