Note: Descriptions are shown in the official language in which they were submitted.
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This invention pertains to apparatus for coating linear
material. In one of its more specific aspects, the present inven-
tion relates to apparatus for applying a sizing to filaments.
The technology which has been developed for the produc-
tion of glass filaments presently makes possible the production
of filaments having a diameter from approximately 0.0001 inch to
approximately 0.0004 inch, at a rate of from approximately 4,000
feet per minute to 15,000 feet per minute.
One of the major problem areas in a filament forming
technology has been the problem of glass upon glass abrasion.
When glass upon glass abrasion occurs, the glass filaments can
easily be damaged. Damage to the filaments can produce an unaccep-
table end product. Accordingly, abrasion among the filaments
cannot be allowed to occux if a successful filament forming oper-
ation is desired.
To overcome the problem of glass upon glass abrasion
it has been widely theorized that a solid film of material must
separate the filaments at all times to assure physical separation
of the filaments. Of course, if the filaments are physically
separated they cannot abrade upon one another.
To provide the physical separation of the filaments a
number of coating or sizing materials can be applied to the fila-
ments as the filaments are formed. The sizing materials are
applied to the filaments by a variety of coating applicators that
have been developed. However, since the filament forming operation
ta~es place in such a short period of time and the filaments are
traveling so rapidly, it is very difficult to apply the sizing
material so that it completely covers the filaments as they are
formed.
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A recent development has been the use of roll type
applicators to apply the sizing to the filaments during the
filament forming process. The roll type applicator comprises a
support-mounted applicator roll that is rotatable about a central
axis and a pressure confining feed passage discharging tangentially
across the width of the roll. The sizing is supplied to the feed
passageway so that the sizing passes along the passageway and is
deposited upon the surface of the ap~licator roll as the sizing
leaves the passageway. The filaments that are to be coated are
then passed across that portion of the applicator roll where the
sizing is deposited from the feed passageway and the filaments
become coated as the filaments remove the sizing from the applica-
tor roll.
This type of applicator can work fairly effectively but
it is difficult to obtain the proper uniform distribution of sizing
on the applicator roll. The problem of obtaining the proper
amount of sizing on t:he applicator roll is further complicated
when the speeds at which the filaments are passing the applicator
roll are considered. In any event when the proper uniform distri-
bution of sizing is not present on the applicator roll the filamentsdo not receive the proper coating. When this happens, voids or
bare spots can occur on the filaments and the glass upon glass
abrasion problem again becomes significant. In practice it has
proven to be very difficult to obtain the proper uniform sizing
distribution across the width of the applicator roll because it
is difficult to obtain a uniform distribution of sizing in the feed
passageway. One reason for the non-uniform distribution of sizing
in the feed passageway is that the sizings normally used have a
tendency to channel in a narrow area of the feed passageway and not
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completely fill the passageway. Of course, when the channeling
occurs the sizing is not uniformly distributed in the feed chamber.
Also, there is usually a certain amount of turbulent flow of sizing
in the feed passageway, and as a result air bubbles are often
trapped in the si~ing. When the sizing is transferred to the
applica.or roll the air bubbles are also transferred to the appli-
cator roll. If a fllament is drawn through the area where an air
bubble is locatedr the filament will not pick up enough sizing to
be properly coated. As a result bare spots can exist on the fiia-
ment and abrasion again becomes a problem.
An object of the present invention is to provide appara-
tus which provides improved uniformity of distribution of coating
liquid to material to be coated.
According to the invention there is provided apparatus
for coating linear material with a liquid comprising:
a chamber having a backwall, a bottom wall, a top wall
and two sidewalls, the bottom wall having at least one aperture
for the introduction of a liquid into the chamber;
an elongated outlet opening at the front of the chamber
for outflow of the liquid from the charnber;
a protrusion extending from the top wall to the bottom
wall, the protrusion extending forwardly from the backwall and
having sidewalls which intersect at an apex of the protrusion pos-
itioned in the chamber so that the apex is spaced apart from the
opening; and,
a rotatable liquid applic~tor positioned proximate the ~-`
opening wherein liquid flowing from the opening is distributed uni-
formly on said applicator during use of the apparatus.
The apparatus of the invention is particularly useful in
the process of forming filaments of heat-softened mineral material
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such as molten glass. In these processes a liquid coating or
sizing is applied to individual glass filaments and the glass
filaments combined into an untwisted filament bundle or glass
strand that is wound onto a package. But the apparatus of the
invention is useful in other processes that treat other types of
linear n~aterial (for example, filament bundles such as yarn, cord,
roving, etc. as well as monofilaments) made from glass or other
filament forming material such as nylon and polyester. Thus, the
disclosure of treating glass strand is only an example to explain
the operation of the invention. The term "filaments" used in the
specification and claims includes monofilaments and filament
bundles, including bundles of continuous or discontinuous synthetic
filaments with or without twist, in addition to bundles of natural
filaments.
In the drawings, which illustrate a preferred embodiment
of the invention:-
Figure 1 is a side elevation view of the applicator inoperation.
Figure 2 is a front elevation view of the applicator in
peration.
Figure 3 is a top view of the applicator.
Figure 4 i5 a cross sectional view (taken along line
4-4 in Figure 2) of the fluid chamber of the applicator.
Figures 1 and 2 show an applicator 1 for applying liquid
sizing to filaments. The applicator has a top block 3 and a bottom
block 5. In one surface of the top block there is a chamber 7.
The chamber terminates in an elongated outlet opening 11 in the
front wall 9 of the top block. The chamber has a height as indica-
ted by the height 12 of the backwall of the chamber 27. The chamber
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is connected to a source of fluid sizing by passageways 13 that
pass through the bottom block and which open into chamber 7. The
fluid sizing material is supplied to the passageways by any suit-
able means (not shown~. The bottom block has an exterior groove
17 along one lateral edge. The groove is semi-circular in shape
and has a diameter that is substantially the same as the height
of the bottom block. A rotatable applicator roll 19 ls positioned
in the groove so that a portion of the applicator roll projects
beyond the open end of the groove adjacent the elongated opening.
Figures 3 and 4 show the design of the chamber 7 that
is utilized in this invention to provide a uniform film of sizing
to the outlet. The sizing enters the chamber through apertures
25 that are in communication with the fluid passageways 13. At
least one such aperture is used to supply fluid to the chamber
from at least one such fluid passageway. To help provide the
uniform distribution of sizing the sidewalls 21 of the chamber
are constructed so that they are preferably parallel to one another.
The sidewalls 21 are also preferably perpendicular to the longi-
tudinal axis of the opening from the chamber.
In addition, to help provide a uniform sizing distri-
bution, the sidewalls and the backwall of the chamber are connected
together by a curved wall portion that forms a radius at the rear
of the chamber. The curved wall portion provides a surface that
acts to direct the sizing from the backwall and corner along the
sidewalls of the chamber.
Also, in the chamber there is a protrusion 28 having a
base 29 and intersecting sidewalls 31. The base of the protrusion
is positioned in contact with the backwall of the chamber. The
protrusion is constructed so that the protrusion extends from the
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bottom wall of the chamber 7 to the top of the chamber 7. The
sidewalls of the protrusion intersect at an apex 33 positioned in
the chamber so that the apex is spaced apart from the opening.
The angle between the intersecting sidewalls of the
protrusion should be in the range of about 60 to about 70 for
the sidewalls of the protrusion to function effectively. However,
in practice it has been found that it is preferable to have an
angle of approximately 60 between the two intersecting sidewalls
of the protrusion and for the two sidewalls of the protrusion to
be approximately the same length to obtain the best distribution
of the sizing. Also it has been found that the protrusion should
extend into the chamber from the backwall about one half the
distance from the backwall of the chamber to the opening of the
chamber. A protrusion that extends halfway into the chamber
provides sidewalls of sufficient length for the sizing to move in
a uniform manner into the center of the chamber.
An additional feature that can be used in conjunction
with the protrusion is a curved portion in the sidewalls of the
protrusion forming a radius where the intersecting sidewalls join
the backwall of the chamber. The curved portion of the sidewalls
of the protrusion helps to eliminate any dead spots where the
protrusion and backwall are connected.
Although the coating apparatus has been described as
having at least one aperture it should be noted that almost any
`~ number of apertures can work in the applicator. However, it has
been found that four apertures 25 are satisfactory in most situ-
ations. The apertures are also positioned so that they are in
that portion of the chamber that is between the backwall of the
chamber and a plane that is perpendicular to the sidewalls of the
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chamber and passes through the apex of the protrusion. When the
apertures are in this location the protrusion func-tions very effec-
tively to distribute the sizing in the chamber.
In operation a fluid sizing is supplied to the chamber
7, through the passageways 13. The sizing passes through the
chamber and exits through the elongated opening onto the applica-
tor roll. Filaments are then drawn over the applicator roll so
that they are coated with the fluid sizing located on the appli-
cator roll. Tne applicator roll will be rotating
so that a different portion of the roll, containing a fresh quan-
tity of sizing, is supplied to the advancing filaments.
To effectively coat the filaments passed across the
applicator roll the uniform distribution of sizing must be pre-
sented on the applicator roll. To obtain the uniform distribution
of sizing, enough sizing must be supplied to the chamber to com-
pletely fill the chamber. ~hen the chamber is completely filled
with sizing, the opening from the chamber will be completely
filled with sizing and a uniform distribution of sizing will be
distributed on the applicator roll from the opening.
However, it is difficult to completely fill the chamber
with sizing because the sizings usually used in this applicator
have a tendency to channel into a narrow area of the chamber and
not completely fill the chamber. To help overcome the channeling
problem the sidewalls of the chamber are constructed so that they
are preferably parallel to one another. The parallel sidewalls
of the chamber establish a uniform width for the chamber so that
a uniform film of sizing will be present along the sidewalls of
the chamber. The uniform film of sizing along the sidewalls of
the chamber results in a better and more uniform concentration of
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sizing at the end region of the opening. This results in a more
uniform film of sizing on the applicator roll.
The curved wall portion, where the sidewalls and back-
wall of the chamber are connected together, also helps reduce
channeling of the sizing in the chamber. The curved portion
provides a surface that acts to direct the sizing from the back-
wall and corner along the sidewall of the chamber. The curved
wall portion helps to eliminate dead spots along the backwall and
the corners of the chamber. Dead spots are areas within the
chamber where the sizing becomes trapped and as a result the
sizing remains in that area of the chamber instead of flowing
through the chamber to the opening. Dead spots can interrllpt or
disrupt the uniform flow of the sizing in the chamber so it is
important that they be eliminated.
In addition, the protrusion in the chamber helps to
provide a uniform distribution of sizing in the chamber, and
reduces the tendency of the sizing to channel into narrow
areas of the chamber. The function of the protrusion is to help
the sizing from the apertures flow smoothly and uniformly into
the center of the chamber. The sizing flows along the inter-
secting sidewalls of the protrusion and uniformly flows to the
center of the chamber. At the apex, the sizing from the aper-
tures flows together and fills the center region of the chamber.
The protrusion provides a srnooth transition for the sizing and
the smooth transition results in a substantially uniform distri-
bution of sizing in the center of the chamber. Since the side-
walls of the protrusion intersect at an apex spaced apart from the
opening, the sizing from ~he apertures will flow together and
establish a uniform distribution of sizing in the center region
of the chamber p~ior to passing through the opening. The side-
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walls of the protrusion can also be joined to the backwall of
the chamber with a curved wall portion to eliminate any dead
spots where the protrusion and backwall are connected. The
curved wall portions on the sidewalls of the protrusion will
help the sizing flow smoothly along the intersecting sidewalls.
The chamber of the applicator, as described above, also
acts to cause the sizing to move in a laminar flow and the
laminar flow reduces turbulence and further improves the uni-
formity and distribution of sizing in the chamber of the
applicator.
The applicator of this invention can be used with
most sizings that are applied to glass filaments or other
filaments that are formed from heat-softened material. However,
- a sizing that is a high viscosity liquid or a gel will normally
be used with the applicator. Sizings classified as thixotropic -
are very suitable for this applicator as are other sizings that
can be applied in a thin sheet to the applicator roll. In
practice, it has been found that a sieing with a viscosity in
the range of 60 to :L200 centipoise will work very well in the
applicator.
Having described an embodiment of the invention in
detail and with reference to the drawings, it will be understood
that such specifications are given for the sake of explanation.
Various modifications and substitutes other than those cited
can be made without departing from the scope of the invention
as defined by the following claims.
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