Note: Descriptions are shown in the official language in which they were submitted.
A METHOD AND APPARATUS
1 FOR COLLECTING FIBROUS MATERIAL
Background of the Invention
Field of the Invention
The present invention relates to a fiber collection
system. More particularly, the present invention relates to
a method and apparatus for collecting fibrous material, e.g.
glass microfibers.
Description of the Prior Art
One conventional method of forming glass fibers
utilizes hot, high velocity gaseous blasts to attenuate the
fibers during formation. The gaseous blasts with entrained
fibers and a large volume of inspirated process air are
- contained and conducted by a forming tube and discharged
into a collection chamber and onto a moving perforated
collection surface upon which the fibers are collected. A
suction means draws spent gas and air through the collection
surface.
Emission control problems arise with such a known
method, particularly with the production of small diameter
or microfibers (e.g. 0.05-2.60 micron diameter flbers and
; typically 0.1 to 0.7 micron diameter fibers) due to the
difficulty of efficiently handling a large volume of moving
gases. Furthermore, the gas entrained fibers tend to escape
into the ambient surroundings, especially in the regions
adjacent the moving collection surface and the collection
chamber. The collection surface often becomes clogged with
fibers which causes fibers to be blown around the production
area since a fiber clogged collection surface prevents
efficient exhausting of the gases. This clogging problem
necessitates replacing the collection surface, e.g. screen
material, frequently. This substantially diminishes the
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efficiency of the system due to interrup-ted production and excessive
down-time. In addition, it i5 often necessary to install expensive
emission control syskems to avoid discharging fibers into the atmosphere.
~rief Descr ~ nvention
In view of the foregoing it is an object of the present invention
to provide an apparatus for the efficient and effective collection of
fibers, p~rticularly microfibers.
Another object of the invention is to provide a microfiber
collection appara-tus which minimi7es emission of fibers to t~e environment
thereby reducing the need for supplemental emission control systems.
A fur-t~er object of the present invention is to provide an
efficient method of collecting fibers.
Another object of the inven-tion is to eliminate or substantially
reduce the need to preheat process air.
Accordingly, the present invention provides a method and
apparatus for oollecting fibrous material which includes a collection
cha~ber and a rotating fluid pervious collection drum pre~erably having a
fine mesh screen po~itioned around its peripheral surface. The peripheral
surface of the oollection drum is rotated along a path, a major portio~,
i.e. at least half, of which is within the collection ch3~her, and a minor
portion of which is located outside the collection chamber. Fibrous
material is drawn onto ~he peripheral surface of the collection drum moving
along the portion of ~he pat'n within the oollection chamber. The portion
of -the pa-th outside the collection chamber is sealed from the interior of
the collection ch~mker. ~ne collected fibrous rnaterial is removed rom ~he
pQth ~hile the peripheral surface of the collection dru~ m~ves through the
portion o~ the path outside the oollection chamber~
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Brief Description of the Drawin~s
FIG. 1 is a perspective view of a collection
chamber of an apparatus for the formation and collection of
fibers according to the present inventiori partially cut away
to illustrate the interior and detail of a collection drum;
FIG. 2 is an end view of the collection drum shown
as FIG. 1 with associated equipment;
FIG. 3 is an end view of the drum and associated
equipment taken from the same position as FIG. 2 but with
the chamber wall and drum end removed;
FIG. 4 is an enlarged, fragmentary sectional view
of an air knife;
FIG. 5 is a sectional view of a baffle plate and
the collection drum taken along line 5-5 of FIG. 3 with
their associated seals;
FIG. 6 is a schematic view and side elevation
illustrating a modification of the present invention;
FIG. 7 is a fragmentary sectional view taken along
line 7-7 of FIG. 3; and
FIG. 8 is a schematic view and side elevation
illustrating a modification of the present invention.
Detailed Description of the Invention
Referring to FIG. 1, in a collection apparatus 10,
filaments of glass F are continuously advanced transversely
into hot, high velocity gaseous blasts B produced by a
plurality of burners 14. The burners 14 are preferably
arranged so as to discharge substantially horizontal blasts.
The gaseous blasts ~ attenuate the filaments F into fine
staple fibers. The gaseous blasts, the fibers entrained
therein and inspirated process air, generally indicated by
arrows A, are contained and directed via a forming tube 15
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1 and are discharged into a collection chamber 16 încluding a
rotatable collection drum 17.
The inspirated air is preferably drawn in along
the path indicated by the arrows A in FIG. 1 through a set
of louvers 12 which can be adjusted so as to control the
amount of air inspirated into the forming tube 15. A wall
11 helps contain and channel the process air through the
louvers 12 where the air ;s then insp;rated ;nto the forming
tube. With such a system, process air need not be drawn
from the area behind the burners 14 where operators monitoring
the process are typically located. Consequently, any air
drawn through the area behind the burners needs to be heated
so as to maintain comfortable working conditions for the
operators. Thus, with the louvers of the present invention
whereby air is inspirated into the forming tube 15 along the
path indicated by the arrows A, there is no need to heat the
process air.
The collection drum 17 is adapted to be rotated in
the direction indicated by the arrows in FIGS. 1 and 3 and
may be driven by any suitable means. The collection drum 17
has a peripheral collection surface 25 which rotates along a
path, a major portion of which path is within the collection
chamber 16 and a minor portion of which is outside the
collection chamber 16.
In the embodiment illustrated in FIG. 1, the
forming tube 15 is comprised of one section having a rela-
tively small cross-section at the end adjacent the burners
14. The cross section of the end of the forming tube 15
adjacent the collection chamber 16 ;s comparatively large
and results in the discharge of the fibers over a substantial
portion of the collection surface w;thin the collection
chamber 16.
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33
1 Other configurations for the forming tube 15 would
be suitable for use with the collection apparatus 10 of the
present invention. For example as shown in FIG. 8, a forming
tube 15a can have multiple sections. In such a modification,
a first section llO, pos;tioned adjacent the burners 14, is
arranged substantially horizontally. This first section may
be constructed of any suitable refractory material, e.g.
panels of asbestos fibers and diatomaceous silica marketed
under the registered Trademark MARINITE by Johns-Manville
Corporation. A refractory material is necessary since the
temperature at the burners 14 is approximately 3000F.
A second section, or mid-section 112 of the forming
tube 15a is positioned intermediate the first section 110
and a third section 114. The mid-section 112 of the forming
tube 15a i5 constructed of any su;table material, e.g.
stainless steel and is oriented in such a manner that the
end of the mid-section attached to the third section 114 is
substantially lower than the end of the mid-section attached
to the first section. In this modification of the present
invention, such an orientation serves to lower the fiber
path in such a manner that the fibers enter a collection
chamber 16a at a point beneath collection drum 17a. Any
other suitable method of achieving this end, that is entry
of the fibers from a point beneath the collection drum,
would also be suitable. For example, the collection drum
17a can be positioned relatively higher than the burners 14
and the forming tube 15a could then be oriented in a sub-
stantially horizontal position.
The end of the mid-section 112 attached to the
third section 114 typically has a greater cross-sectional
area than the end of the mid-section attached to the first
1 section 110. The increased cross-sectional area of the
downstream end of the mid-section serves to slow down the
velocity of the gaseous stream and entrained fibers.
The third section 114 of the forming tube 15a is
attached at one end to the mid-section and its other end is
open to the collection chamber 16a. The third section is of
substantially constant cross-section and, like the mid-
section, can be constructed of stainless steel. The third
section 114 is oriented in a substantially horizontal position
and opens into the collection chamber 16a at a point beneath
the collection drum thereby preventing direct impingement of
the fibers onto the collection screen of the collection
drum. This minimizes fiber penetration into and through the
collection screen mesh, thereby minimizing emission problems
and clogging of the collection screen surface.
Other orientations of the forming tube in this
embodiment are suitable, e.g. the forming tube 15a can open
into the collection chamber at a point above the collection
drum or the forming tube can also be oriented to open in
such a manner that the axis of the forming tube, that is the
major directional line of travel for the fibers, is at some
angle other than perpendicular to the rotational axis of the
collection drum. With such systems, although the suction
force still draws the fibers onto the collection screen, the
fibers are not directly impelled onto the collection screen
by the force of the gaseous blasts B and the inspirated
process air.
In the illustrated embodiment (see FIGS. 2 and 7),
a sprocket 18 is connected by a tubular stub shaft 19 (FIG.
7) to a rotatable end plate 22, and is chain driven by an
electric motor 23 or other suitable source of power. The
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1 tubular stub shaft 19 is supported for rotation by bearings
housed in a journal box 20. The journal box 20 and the
electric motor 23 are supported by a beam 24 which is attached
to a suitable framing structure 11. The end of the drum
opposite the drive end, that is, the end adjacent an exhaust
duct 33 (FIG. 1) is similarly supported; i.e. a spider 27
(FIG. 3) is supported by a tubular stub shaft 28 which
rotates in a journal box 29 (FIG. 7). The journal box 29 is
mounted on a beam 32, also supported by the framing struc-
ture 11.
The peripheral surface 25, of the collection
drum 17 is made of a perforated metal sheet. Hot rolled
steel 5/16 inch thick and having 2 1/16 inch square holes
punched on 2 3/8 inch centers in staggered rows, is suitable.
Other types of perforated metal can be used for the col-
lection drum surface, e.g. round holes, oblong holes, etc.
or flattened expanded sheet metal. A fine mesh collection
screen 26, e.g. a stainless-steel wire cloth -is attached to
the peripheral surface 25. The collection screen 26 can be
attached to the periphery of the collection drum 17 with a
high temperature epoxy adhesive and ioined to itself at its
overlapping edges by epoxy and silver solder. Other suitable
means of attaching the screen to the collection drum surface
can be used, e.g. "snap-in" sections which decrease replacement
time. The size of the screen mesh is dependent on the size
of the fibers to be collected. Finer mesh size is utilized
for small diameter fibers and larger screen is used for
coarser fiber collection. A 32 mesh screen (.0238 inch wide
openings) has been found to be quite suitable for the col-
lection of microfibers.
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1 Finer mesh screens, e.g. 46 mesh (with .0172 inch
wide openings) allow lower fiber emission rates into the
exhaust but tend to have a shorter operating life. Such
shorter operating life is due to the smaller diameter wire
in such finer mesh screens which wears through more rapidly
than the wire in coarser screens and which tends to flex
more in place causing the wire to break more rapidly.
The finer mesh screen operating life problem can
be satisfactorily handled by improved fastening methods for
attaching the screen to the collection drum. For example,
multiple discrete snap-in segments can be used which have
less of a flex tendency than a continuous sheet of screen
and are easier to replace when the screen does wear.
For a given rate of the production, the collection
drum is rotated faster for the collection of fine diameter
fibers than for the collection of coarse fibers since finer
fibers tend to block the screen holes more rapidly.
In an actual working embodiment of the present
invention, the speed of the rotation of the collection drum
is set so as to maintain a collection screen loading of 2.63
grams of fibers per square foot. However, slower rotational
speeds can be used, e.g. 3.31 gms/sq. ft. load;ng, but
slower rotational speed results in a high pressure drop
across the fibers and collection screen which forces the
fibers into and through the interstices of the screen
resulting in fiber emission through the exhaust duct 33.
The spiders 27 at the end of the drum 17 adjacent
the exhaust duct 33 provide openings so that the interior of
the collection drum 17 communicates (as indicated by arrow E
in FIG. 7) via the exhaust duct 33 with a suitable large-
capacity exhaust or suction blower (not shown). The exhaust
1 duct 33 may also be equipped with conventional dampers to
control the amount of air drawn through the collection drum.
As shown in FIG. 3, an approximately 80 segment
of the peripheral wall of the collection drum 17 is separated
from the suction effect of the exhaust blower by an arcuate
baffle plate 34. This section of the collection drum 17 is
exposed to the atmosphere on the outside of the collection
chamber 16. The baffle plate 34 is positioned on the interior
wall of the peripheral surface 25 by a support member 35
(FIGS. 1 and 3) which ;n turn ;s secured to a stationary
tubular shaft 30. As shown in FIG. 7, the tubular shaft 30
is mounted in a block 37 which ;s fastened to a base plate
38 mounted on the beam 32. A key 41 locks the tubular shaft
30 aga;nst rotat;on. The tubular shaft 30 extends axially
through the interior of the collection drum 17 and is supported
at the drive end of the collection drum 17 by bearings 40
located at the hub of the tubular stub shaft 19 on wh;ch the
sprocket 18 rotates relative to the stat;onary shaft 30.
The baffle plate 34 is sealed aga;nst the interior surface
of the collection drum 17 along its upper and lower Pdges by
longitudinally extend;ng flex;ble seals 44 and 45 (FIG. 3~,
and, as shown in FIG. 5, along its side edges by seals 46.
The flexible seals 44 and 45 and the two seals 46
are held in pos;tion in a seal;ng relat;onsh;p by metal
angles which press the seals against the peripheral surface
25 of the collection drum. The seals 44, 45 and 46 are
preferably made of a polytetrafluoroethylene impregnated
asbestos fabric, e.g. ASBESTAN material produced by Johns-
Manville Corporation which is a Teflon (trademark of E. I.0du Pont de Nemours Co.) impregnated asbestos fabric.
33
As shown in FIG. 7, two additional seals 43 and 47 are provided
and are preferably comprised of a polytetraEluoroethylene impregna-ted
fabric such as ASBESTAN fabric. The seal 47 is disposed between the end
plate 22 of the collection drum 17 and the collection chamber 16. The seal
47 is positioned in such a m~nner that air adjacent t~e exterior of the
collection chamber is not inspirated into the collection chamher. The seal
43 is positioned between the collection chamber 16 and the exhaust duct 33.
The seal 43 prevents fibrous material frcm bypassing the collection screen
and entering directly into the exhaust duct 33.
A baE1e plate 34a (FIG. 8) is similarly sealed as the baffle
plate 34 and serves a similar function, i.e. it inhibits the suction force
within the collection drum 17a rom acting on that portion of t~e path of
the peripheral surface of the collection drum outside the collection
cha~ber 16a.
As shown in FIGS. 1, 2, and 3, an air knife 48 is attached along
the longitudinal lower edge of the baffle plate 34 and includes
longitudinally extending fluid nozzles positioned to clean residual fibers
from the collection screen 26 and the peripheral surface 25 of the
collection drum 17 after the Eibers have been removed frcm t~e collection
screen at a point of the path outside the c~llection chamber 16. Due to
the longitudinally extending seal 45, the air knife 48 operates without
influence from the low pressure zone within the collection dr~m.
Compressed air or other fluid under low pressure and high volume (e.g.
approximately 5.5 psi and 635 cfm) i5 fed to the air knife 48 from a source
50 external of the apparatus framing structure 11 and via a plurality of
pipes 49, which are connected through the center of the stationary shaft 30
at nipples 100.
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1 In operation, the gaseous blasts B, the inspirated
air drawn along the path indicated by the arrows A, and the
entrained fibers are discharged into the collection chamber
16 via the for~ing tube 15. A major portion, e.g. approximately
280 of the screen-covered collection drum surface, serves
as a wall within the collection chamber and thereby intercepts
the f;bers. As shown in FIG. 3, a longitudinally extending
outer seal 51 and a longitudinally extending upper outer
seal 52 which cooperates with an idler roll 53 also help
confine the gaseous stream of fibers within the collection
chamber. The idler roll 53 serves as a moving seal that is
adjustable to varying collection thicknesses while still
maintaining an effective seal between the atmosphere and the
collection chamber 16.
The suct;on established within the drum interior
by the exhaust blower through the exhaust duct 33, continuously
draws spent gases and process air through the screen-covered
collection drum surface. The fibers entrained in the gaseous
blasts are collected on the collection screen 26 and are
held on the screen by suction force until the collection
drum rotates to a point beyond the idler roll 53 i.e. to a
point along the path which is outside the collection chamber
16. The baffle plate 34, appropriately sealed as described
above, confines the suction effect to the major portion of
the screen, e.g. the 280 portion, that is moving within the
collection chamber at any given moment. The baffled portion
of the drum, e.g. the approximately 80 which is exposed to
the atmosphere, is utilized for removing the collected
fibers from the path.
In the embodiment of the present invention -illus-
trated in FIG. 8 the baffle plate 34a is attached to an air
1 1 _
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1 knife 48a in a similar manner as that discussed above with
regard to baffle plate 34 and the air knife 48. The air
knife 48a cleans any residual fibers from the collection
drum 17a and its collection screen after collected fibers
102 are removed from the path at a point outside the collec-
tion chamber 16a.
In another embodiment of the invention, fibers are
collected by a conveyor belt 101 as shown in FIG. 6. In
this embodiment, the collection screen 26 lies against the
peripheral surface 25 of the collection drum while it is
within the collection chamber 16, preferably, for example
approximately 250 of the circumference of the collection
drum 17. The conveyor belt 101 is mounted on a roller 21
and travels from a position adjacent the collection drurn to
a material take-off position outside the collection chamber
16. As FIG. 6 further illustrates, an air knife 48b, which
is similar in construction to the air knife 48, discharges a
high volume fluid jet through the collection screen 26 and
conveyor belt 101 thereby cleaning residual fibers from the
collection screen and conveyor belt and into the collection
chamber 16.
The collected fibers can be taken off the collection
screen in several ways. FIG. 6 illustrates one method
wherein a lightweight gathering mandrel 56, controlled by
appropriate guides 57, is laid against a layer of collected
fibers 102 and an initial wrap is manually performed so as
to form a first layer around the mandrel. Thereafter the
gathering mandrel 56 is frictionally rotated and wind-up of
the collected fibers 102 continues until a predetermined
roll size is achieved. The mandrel is then replaced by an
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1 empty one. The wrapped material can then be stripped from
the completed mandrel and packaged for shipment.
The gathering mandrel is preferably changed fre-
quently, e.g. approx;mately every 10 minutes for an operation
producing 60 pounds of fiber per hour. This produces a
package of approximately 10 pounds when collecting .5-.7
micron diameter fiber. S;nce the collection screen 26
gradually retains more fibers as the mandrel package is
build;ng, the amount of a;r passing through the screen is
reduced which thereby reduces the static pressure within the
forming tube. A small mandrel, e.g. an empty gathering
mandrel, removes the f;bers from the collect;on screen more
eff;c;ently wh;ch thereby presents more open area for a;r
passage thus ;ncreas;ng the forming static pressure and
reducing the temperature in the exhaust gas since more air
can be ;nsp;rated into the forming tube.
A second method of winding the collected fibers
102 util;zes a multi-position turret which is adapted to
receive three rotatable gathering mandrels aligned such that
the rotat;onal axis of each mandrel is parallel to the
rotational axis of the collection drum. After one of the
gathering mandrels is fully wrapped, the turret is rotated
to bring an empty gather;ng mandrel ;nto pos;tion against
the collection screen for wind;ng the collected fibers 102.
A third method of w;nding the collected f;bers is
;llustrated ;n FIG. 2 and involves a "flip-flop" arrangement
58. First and second mandrels 56a and 56b are rotably
mounted on either end of a bar 103 having a counterweight
105 acting on its center. The first mandrel 56a beg;ns
w;nd;ng the collected f;bers 102. Upon reaching a pre-
determined package size and weight on the first mandrel 56a,
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1 the second mandrel 56b is swung over to a point on the
collection drum surface between the idler roll 53 and the
wind-up position, indicated at reference numeral 107. The
first mandrel 56a is then pulled outwardiy away from the
collection screen 26 and the second mandrel 56b drops into
the proper wind-up pos;tion at 107. The second mandrel 56b
is pre-wetted which causes the collected fibers 102 to begin
winding around the second mandrel 56b. During the winding
operation on the second mandrel, the fibers can be stripped
from the first mandrel 56a so that upon completion of the
wrapping process on the second mandrel 56b, the process can
be repeated.
Other methods of collecting the fibers from the
screen can be utilized. For example the fibers can be
vacuumed from the screen rather than frlctionally winding
them onto a rotating mandrel. In an embodiment wherein the
collection apparatus utilizes 30,000 cubic feet of air per
minute, fibers can be vacuumed off the collection screen and
recollected with a vacuum force of approximately 600-700
cfm. In another method the collection screen can be supplied
with a pervious paper or felt upon which the fibers can be
collected. The collected fibers and the felt or paper can
then be removed together by, for example, one of the winding
operations discussed above.
Any fibers that may remain upon the screen after
such removal are cleaned by a high vo1ume fluid jet e.g. by
the air knife 48, 48a or 48b. Clogging of the collection
screen 26 with residual fibers is thereby prevented, and
since the air knife is positioned so as to discharge the
fibers into the collection chamber 16, the screen is not
only efficiently cleaned but atmospheric emissions of fibers
is also minimized.
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1 Furthermore~ since the fibers are discharged into
the collection chamber 16 they can be recollected on the
collection drum. This minimizes operator exposure to the
fibers and also eliminates scrap from the process which
results in more efficient and economical collection system
than that of the prior art.
It is apparent that, within the scope of the
inventlon, modifications and different arrangements may be
made other than herein disclosed, and the present disclosure
is illustrative merely~ the invention comprehendin~ all
variations thereof.
