Note: Descriptions are shown in the official language in which they were submitted.
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This invention is directed to a web saturator or coater
which accepts a web moving therepast and saturates or coats
same before its passage onto another work operation such as
a d~ying procedure.
The invention relates to an apparatus for and m~thod
of saturating or coating a travelling web of material by means
of a controlled curtain of the saturant or coating.
The travelling web is treated by th~ controlled cascading
of the saturant over an inclined slideway and applying same
in the ~orm of a free~falling vertical curtain of the saturan~
which impinges onto the travelling web so as to form a layer
thereupon and/or to saturate therethrough9 according to the
particular characteristics of the saturant and/or of the web,
and/or the exploitation of varlous suction devices according
to the desired characteri~tics of the end product.
The apparatus may be used singly to allow a single layer
o the coating, surh as a binder, to be added to the
travelling webt or a plurality thereof may be used in tandem
ZO to allow a plurality of seriatim layers of coatlng ~o b~ added
~hereto And if desired, the apparatus may be used ~ooperantly
with a series o suction or vacuum devices for purposes of
more precisely conditioning the web by a progressive series
of operatians applying varyin~ degrees of neg~tive pressu~e.
The primary object of the invention is to provide a method
of saturating or coating a travelling web with a layer or layers
of an appropriate liquid composition such as a binder by the
steps of moving the w~b along a path through a work zone and
3Q orming at the work zon~ a free~falling vertical curtain of the
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saturan~ or coating extendîng transversely oE the web path and
impinging same on the travelling web.
In the preferred embodiment~ the apparatus comprises
means for forming a free-fallîng vertical curtain inclusiv~
of a well or reservoir or cavity for containing the saturating
or coating composition and flowing same outwardly therefrom
through a pressurized headbox, over a dam on the downstream
side of the well and along an inGlined slide through a
variable slice disposed adjacent the slide, with the slida
terminating in a lip along its lowermost edge from whence the
liquid ~alls by gravity as a vertically disposed curtain onto
the travelling web therebelow.
An air pressure chamber is provided to permit the
discharge of a controlled increased amount of binder to the web.
Additionally, the apparatus is provided with a lip which
can be adjusted uniformly across the machine width and relati~e
- to the inclined slide and with a mechanlcal jack arrangernent
located on top of the air cap for controlling the siæe of the
defined slice between lip and slide.
It can also be adjusted by means of a plurality of
microjacks positioned at intervals across the machine width so
as to allo~ the diseharge of a variable amount of binder in
aeeordance with the set lip opening at ~he ~fferent intervals
along the machine width, wherefor a rela~ively heavy or light
discharge of the binder can be made centrally of the web and/or
at one side of the median line thereof and~or at a side edge
of the web, all as may be desired~
Advantageously, means may be provided for varying the
vertical spacing between the terminus of the slide lip and web
moving along the path~ thereby regulating the curtain height;
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the distanc~ over which free fall occurs depending on the
nature of ~he specific application involved and the
characteristics of the particular liquid co~position
employ~d. In selecting any optimum height for any particular
application, a chief criterion is to make the height as small
as practical while yet af~ording a desired result. The
greater the curtain height, khe more susceptible it is to
being affected by such as ambient air currents which may
create curtain fluctuations with unwanted attendant variations
in the depos;ted layer on the web.
A vertical height has to be selected whi h will satisfy
the dictate that the free falling curtain w;ll have such
momentum upon impingement that ;t will penetrate any existing
air barxier or at least will displace it so as to permit the
desideratum of adhering to the web or penetrating theret~rough.
Any air barrier so encountered may be found to vary with such
different factors as the surface character of the work being
treated, and the velocity of the work ~s it is advanced
relative to the apparatus.
The law of momentum, as the product of velocity and mass,
teaches that, if the rate of liquid flow is reduced, while the
web velocity of the web remains constant, the height of
free-fall must, normally, be increased in order to inc~ease
the implngment velocity and to give the free-falling curtain
such adequacy of momentum as to penetrate the alr barrier
without disruptionO
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings will serve to illustrate the
-method and apparatus of the present invention? and thereîn:
Figo 1 is a sectional elevational view of the
apparatus of the invention 3 and
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Fig. 2 is a transvers~ sectional view through
a typical treated web show;ng the
effect of varying the amount of deposition
of binder thereon.
DETAILED DESCRIPTION
The apparatus is shown as including a pair of spaced
vertically-extending stands lO, each being footed sn a mill
flooring F on opposite sides of a travelling wire or belt B
upon which a web or work W is moved past and below the
to-be-described operatlng mechanism of the apparatus.
A clevis 14 extends upwardly from each stand and through
each of which a pin 16 extends for pivotally supporting a oot
18 at bot~ the tending and drive sides of the machine,
Also supported upwardly vertically above a respective
stand 10 on each side of the apparatus is an airride Z0
connected by means (not shown) to a valved air source
(not shown) wherewith pressurized air may be charged to or
released from the airrides for purposes Later to be reerred to.
An adjustable jacking mechanism 21 may be provided on
each stand ~or purposes of elevating the applicator box
about to be described.
Spaced upwardly rom stands lO and from belt B and web W
is a horizontally~extending header 22 which extends centrally
through an applicator box defined by a horizontally extending
bottom wall 24 supported by a lower frame 26~ a tran~sverse
vertically extending rear wall 2$~ an inclined front wall or
slide 3Q, and inwardly converging front and rear top walls 32
and 34 respec~ively, which front and rear top walls are
connected at their lower extremities astride opposite sides of
a slot 36 extending through the topmost portion of header ~2.
Opposite side walls 38 at opposite sides of the applicator box
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complete -the enclosure, all of the walls being interjoined in
conventional manner to define a unitary construction.
If desired, slot 36 through the t~p side Qf header 22
may be substituted for a plurality of spaced apertures,
Header 22 extends outboard of the enclosure through
one of the side walls and will be fed from an outside source
of material (not shown) in this conventional so-called side
inlet manner.
By the means thus far described~ the enclosure may be
raised or lowered upon pins 16 by means of the pressurizing
or releasing of airrides 20 so as to allow ready access
to the transporting or travelling wire B ~or threading or
other purposes as well as to allow the varying of the
vertical distance between the edge of the lip at the lower
terminus of the slide and the travelling wire B.
Upwardly of the applicator box a sea.led pressur~ chamber
is defined by opposite side walls 42, extending upwardly rom arld
connecting with respective side walls 38~ a cover 44 extending
transversely of the apparatus and having a forward portlon 46
terminating at a pivot poin~ 48 and a rearward portion 50
connecting with rear top wall 34, and a lower wall 52 extend-îng
transver~ely oE the appar~tus and extending between pivot puint
48 and a downwardly facing lip 54.
The inside wall of a lip 54 has a transversely-extendîng
sealing lip 56 so as to effectîvely seal off the pressure
chamber~
Pivot 48 mounts a pivot pin 58 by means of which lower
wall 52 may be pivotally moved so that lip 54 îs moved toward
or away from the outer surface of inclined front wall 30
definîng a slide 56~
Pivot 48 is supported by a pair of vertîcally depending
- beams 60 extending d~wnwardly from and pivoted at 62 from the
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respective of a pair of horizontally extending posts 64 which
project outwardly from and are moved in fore and aft directions
as indîcated by arrow a by respective motors 68 mounted on
cover 44.
Selective opera~:ion of motors 68 drives the pos~s 64
fon~ardly or rearwardly and controls the movement o lip 54
toward and away from slide 56 and hence controls the general
dimension of the slice therebetween or the obvious control
of the flow of material passing therethrough.
Pressurized air is introduced to the gas pressure chamber
through a manhole 70 and a level control blow hole 72 allows
maintaining a stock level L in the housing under the pressure
as applied by compressed air hrough the manhole. The level L
is maintained so as to just su~merge the dam or weir 74
defined b~ the apex of ront wall 30 and front top wall 32
over which liquid flows from upwardly from header 22 through
slot 36 (or apertures) into and out of the well thereabove
and thence over the dam and d~wnwardly along the slide.
The usual tending side and dis~ant side deckles (not shown)
are disposed on each side of front wall 36~ which deckles
may be adjusted in inboard and outboard directions for the
known function of varying the work area widtho
The height of the free falling curtain~ that is, the
vertical distance from lip to web over which free fall occurs
can be varied to accommodate to the nature of a specifîc
application and the partlcular characteristics of the liquid
composition therein employed, but preferentially, the height
will be as small as is practical. The higher the curtain9
the greater the opportunity or ambient air currents to take
their toll in curtain fluctuations and resultant varîations
in the manner in which the liquid contacts the web.
3 0 3
Under typic~l operating conditions, the height of the
free~falling curtain will be in the range o 1/4t' to 3/4"
but operations at smaller or greater heights are within the
letter and spirit hereof.
The coating or saturant is continuously fed as a curtain
at a rate at least as great as it is removed by the moving
web, and in order to main~ain the lip of the slide is
positioned in close proximity to the surface of the moving web.
The layer can be oriented in any desired manner with
wide variation permissible with respect to thlckness and/or
viscosity of the particular liquid coating ~mposition.
The space between lip and slide is such that the stock
receiving chamber is closed so that air pressure may be built
up therein by the air inlet.
It is to be appreciated that stock in thls charnber may
be maintained under pressure merely by a suitable stock 10w
pump and without the use of air under pressure as shown.
In either case the sealing means is effective to
maintain such pressure.
The sealing means will co~prlse a rubber sealing strlp.
To increase the mass, certain interior space 100
within the enclosure may be filled with concrete.
A5 shown schematically9 the applicator can be used in
combination with a series of three suction or vacuum boxes 91
93 and 94, wherein suction box 90 is disposed in advance of the
applicator operating area for use in conditioning the web to
attain an optimum or minimum water content before the
initiation of the saturation step, wherein suction box 9
is disposed in the applicator operating area ~or use in
applying a low degree of vacuum so as ~o draw the saturant
~hrough the web and removing any ex~ess thereof~ and wh~rein
suction box 94 is disposed outboard of the applicator
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operat;n~ area for use in ~ine~tuning wi~h minute or
discrete vacuum control so as to allow a retention of the
precise desired amount of saturant on the web or sheet,
The invention is specifically illustrated with no
reference to any other particular type of applicatîon,
although it is to be understood that it offers opportunity or
wide application9 with utilization to advan~age in numerous
fields, wherein it i5 desired to effect application of a
superposed layer of liquid coating composition or of a
liquid saturant.
It will be appreciated that the invention is not limited
to the particuLar construction of the exemplary embodimen-t
illustrated but includes variants and equivalents within the
spirit and the scope of the invention as defined by the claims.
