Note: Descriptions are shown in the official language in which they were submitted.
METHOD AMD APPARATUS FOR
MAKING FIBERS FR~M TT~NU~r~ M~TERIA~S
BACKGROUND AND OBJECTS
This invention relates to the formation of fibers
from attenuable material and while the invention is adapted
for use in the formation of fibers from a wide variety of
attenuable materials, it is particularly suited to the atten-
uation of various thermoplastic materials, especially min-
eral materials such as glass and similar compositions which
are rendered molten by heating. The present invention may -
be employed in connection not only with various mineral
materials, but also with certain organic materials which
are attenuable, such as polystyrene, polypropylene, polycar-
bonate and polyamides. Since the equipment or apparatus
is especially useful in the attenuation of glass and similar
thermoplastic materials, the following description refers
to the use of glass by way of illustration.
Our prior Canadian application Serial No. 290,246,
filed November 4, 1977, and also various other of our Canadian
applications identified hereinafter disclose certain tech-
niques for utilizing whirling ~urrents or tornadoes for
the attenuation of molten glass. In said Canadian applica-
tion 290,246, the system for developing the secondary or
carrier jets which penetrate into the principal current
or blast involves the use of a series of jet orifices deliver-
ing gaseous jets against the surface of an inclined baffle
or deflector, providing for deflection of the jets and for
flow of the deflected jets in directions.
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toward and penetrating the blast in order to develop "toration"
zones, i.e. zones of interaction in the blast characterized
by pairs of tornadoes in which attenuation o~ the glass
streams is effected. In said Canadian application Serial
No. 290,246 the jets and the deflector are arranged so that
the jets tend to spread laterally upon impingement thereof
on the deflector surface, and the spacing of the jets is
sufficiently close to provide for impingement of the jets
upon each other near ~he free edge of the deflector surface.
This impingement and the deflection of the jets results
in development of pairs of whirling currents or tornadoes
adjacent the edges of each jet, and further results in low
pressure zones in each jet just downstream of the edge of
the deflec$or, into which zones ambient gas or air is induced.
In said low pressure zones the gas flow is substantially
laminar, and the streams of molten glass are introduced
into the system in said laminar flow zones, thereby provid- -
ing stability of feed of the glass streams into the system.
The glass streams are then advanced with the flow of each
jet toward the zone of interaction produced by penetration
of each jet into the blast/ with consequent attenuation
of the stream in said zones of interaction.
As in said Canadian application Serial No. 290,246,
the system of the present invention also provides for develop-
ment of toration zones by penetration of jets into a blast
and for attenuation of streams of molten glass in said zones,
but in the system of the present invention the jets are
developed in a different manner, and feed of the streams
of molten glass is differently oriented with relation to
the jets, than in the 290,246 application referred to.
In the system of the present invention, provisionis made for generation of a plurality of jets with their
axes lying in spaced side-by-side planes, which planes
are referred to herein as the median planes of the jets.
S Perpendicular to the median planes, the axes of the jets
initially lie in a common plane which is tangent to a convexly
curved surface of a guiding device~ so that the jets are
subjected to a Coanda effect causing jets to deflect and
follow the curvature of the convexly curved surface of
the guiding device.
The jets are delivered from orifices which are
preferably of greater cross sectional dimension in the
common plane in which the jets are initially generated,
as compared to the cross sectional dimension perpendicular
to said common plane~
With the arrangement of the jets and jet orifices
just described, the deflection of the Coanda deflection
of the jets results in development of a pair of whirling
currents or tornadoes within the flow of each jet, and
the direction of turning of these currents and the inter-
spacing between the jets results in induction of ambient
gas or air adjacent to the surface of the curved guiding
element in the spaces between the jets~ This induced flow
over the surface of the curved guiding element between
the jets represents a substantially laminar flow, and the
streams of molten glass are introduced into this laminar
flow between adjoining jets.
Feed of the glass streams in-to the laminar flow
zones intermediate the ~ets in the region of the surfacc of
the curved guiding element increases the stability of feed
of the glass streams. In a manner more fully explained here-
inafter, each stream of molten glass is then drawn from the
zone of laminar flow into the flow of one of the jets and is
carried thereby into the zone of interaction with the blast,
for attenuation therein. The feed of the glass into the jet
system also effects preliminary attenuation of the glass
stream, as will also be explained.
Notwithstanding the fact that the glass streams
are fed into the influence of the jets in planes intermediate
to the median planes of the jets, a high degree of stability
of feed is provided because the zones of laminar flow into i - -
- which the streams are delivered are located on the surface
of the curved guiding element, which is a fixed structural
part. ¦
In sum~lary of the above, therefore, the present
invention may be broadly seen as providing a process for atten-
uatlng attenuable material comprising generating a pluralityof jets with the jet cores centered in spaced side-by-sidc median
planes and initially directed in a common plane transverse to the
median planes and each jet being of yreater cross-sectional di-
mension in the common plane than in a direction transverse to
the common plane, deflecting the jets including the flow induced
by the jet cores from the common plane by subjecting the jets to
the Coanda effect of a convexly curved surface, the jets being
spaced from each other and the induced flow of the jets develop- ¦
ing zones of laminar flow in regions overlying the Coanda sur-
face between adjoining jets, delivering streams oF at~enuable
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material intermediate the median planes into the zones of
laminar flow to be carried thereby into the jet flow ana
effect attenuation o~ the streams, and generating a gaseous
blast of cross section greater than that of the individual
deflected jets directed transverse to the deflected jets,
the de~lected jet flow having higher kinetic energy per unit
of volume than the blas-t and penetrating the blast to develop
toration zones into which the streams of attenuable material
are carried by the deflected jets.
The above process may be carried out by way of
apparatus for attenuating attenuable material comprising jet
delivery means having a plurality of jet orifices positioned
to deliver spaced gaseous jets in a common plane, each jet
orifice being of larger cross-sectional dimension in the
plane than in a direction transverse the plane, a cJuide ele-
ment having a convexly curved surface with an upstream edge
thereof positioned adjacent bo the jets and serving to deflect
the path of flow of the jets, means for delivering streams
of attenuable material into the influence of gaseous currents
induced by the jets in zones intermediate the jets in regions
of deflection thereof over the curved surface of the guide
element, and means for delivering a gaseous blast of larger
cross section than the individual deflected jets, the blast
being directed transverse to and intercepting the deflected
jets.
BRIEF DESCRIPTION OF THE DRAWINGS:
Figure 1 i5 a somewhat diagramma-tic side eleva-
tional view, with parts in section, illustrating the major
~iber producing and collecting components of a system accord-
ing to the present invention;
Figure 2 is an enlarged somewhat diagram~atic per-
spective view of the major fiber producing components of a
- s~stem according to the present invention incorpora-
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ting a plurality of fiberizing centers each arranged in
the manner above briefly described, this view illustrating
certain parts in section, and having cer~ain portions broken
out in order to facilitate illustration and explanation
of certain characteristics of the system;
Figure 3 is an enlarged vertical sectional view
taken in the median plane of one of the jets and illus-
trating the components of one fiberizing center
Figure 4 is a vertical sectional view similar
to Figure 3 but taken in the plane of one of the glass
delivery devices, which lies in a plane imtermediate the
median planes of adjoining jet devices;
Figure 5 is a view similar to Figures 3 and 4,
but particularly illustrating the interrelationship between
the various components of a fiberizing center, this view
still further indicating certain dimensions and dimensional
relationships to be taken into account, in establishing
operating conditions in accordance with the preferred prac-
tice of the invention;
Figure 6 is a somewhat diagrammatic elevational
view taken as indicated by the line 6-6 on Figure 5 and
also indicating certain dimensional relationships involved
and
Figure 7 is a horizontal sectional view taken
as indicated by the line 7-7 on Figure 5.
DETAILED DESCF~IPTION:
Referring first to the illustration of Figure
1, the reference numeral 10 indicates a blast generator,
having a discharge device 11 from which the blast B is
discharged toward the right as viewed in Figure 1. The
device 10 may be of the burner type, supplied with air
and fuel in any desired manner, as by the supply connection
12.
Figure 2 illustrates jet orifices 22a, 22b, 22c,
22d, 22e and 22f providing for discharge of jets fron the
manifold 13. The jet orifices, and the jet cores delivered
~rom the orifices are centered in spaced side-by-side median
planes, with the jets initially directed in a common plane
transverse to the median planes, each jet orifice being
of greater cross sectional dimension in said common plane
than in a direction transverse to said common plane. In
the preferred arrangement of the invention, the jet orifices
are substantially rectangular with the two dimensions of
the orifices related to each other in the manner more fully
brought out hereinafter in connection with Figures 5 and
6.
As clearly appears in Figures 1 to 4, the jets
b, c, d and e are initially discharged adjacent to the
leading edge of a curved Coanda deflecting element 14,
with the jet cores closely associated with the curved surface.
The jet core bc of the jet b is indicated in Figure 3.
In consequence of the position of delivery of the jets
the Coanda effect of the convexly curved surface of the
element 14 causes the jets, for instance the jet delivered
from orifice 22b, to be deflected in a manner generally
following the curvature of the surface of element 14.
At the same time the jet flow induces ambient gas or air,
this deflection action, coupled with the induced air flow
establishing a pair of whirling curren~s or tornadoes which
appear in Figure 2 at 23b-23b for the jet b in the region
where that jet is broken out for purposes of the illus-
tration. The induced air currents are clearly indicated
by arrows in Figures 2, 3 and 4.
As shown in Figure 2, the direction of turning
of the whirling currents or tornadoes 23b is downwardly
at the side edges of jet b. The same is also true with
respect to the direction of turning of the tornadoes of
jet c, and since the jet orifices are spaced substantially
~rom each other, ambient gas or air is ~nduced between
adjoining jets and is caused to flow in a substantial
laminar fashion over the convex surface of the guide element
14 in the same general direction as the flow of the jets.
Such laminar flow areas are clearly indicated in Figure
2. The laminar flow of these areas is characterized by
relatiYely low pressure and stability or freedom from tur-
bulence, and the molten glass delivery devices 16 are posi-
tioned between the median planes of the jets, preferably
in positions so that the streams of molten glass are introduced
into the system in the laminar flow æones lying between
the jets.
In the feed of molten glass for fiberization
in accordance with the foregoing, the delivery devices
16 advantageously provide for development of glass bulbs
or tips T from which glass streams S are drawn. In Figure
2 it will be noted that such tips Tb, Tc, Td and Te are
shown in a series lying in planes between the median planes
of the jets, tip Tb providing for a stream of glass enter-
ing the jet b, tip Tc and Td providing for development
of glass streams entering jets c and d. Preferably the
glass supply devices 16 and thus the glass tips T, although
located in planes between the median planes of the jets, '
are located closer to one of the adjoining 3ets than to
the other, as will be brought out more fully hereinafter
in connection with Figure 6. This assymetrical location
of the glass supply devices is desirable for the purpose
of assuring that each glass stream will enter the influence ~ -
of a given jet.
Figure 3 is a view taken in the median plane
of the jet orifice 22b and of the jet b delivered from
that orifice, and it will be noted that in this view the
glass discharge device 16 is shown in elevation as is the
glass tip Tb and the stream S which is entering the influence
Of the jet b. In Figure 4 the sectional view is taken
in the plane of the glass delivery device 16 for the glass
tip Tb, and here the delivery device 16 and the glass tip
are shown in section.
In Figures 2, 3 and 4, the entry of the glass
stream S into the jet b is indicated, and in Figure 4 it
will be noted that the lower portion of the glass stream
sl is shown in dotted lines, indicating that this stream
is in the plane of the jet b and is being delivered thereby
into the zone of interaction with the blast B.
In connection with the jet flow oE each jet, it
will be understood that the whirling currents or tornadoes
such as indicated at 23b in Figure 2 are most pronounced
or active in the region adjacent the downstream edge of
the guide element 14. The intensity of the whirling cur-
rents diminishes as the jets proceed downwardly and this
decrease in intensity is indicated by the indefinite lines -:
23C appearing in the region where the jet c is broken out,
about mid way between the downstream edge of the guide ele-
ment 14 and the region where the jet penetrates the blast
B.
Although as the blast B is approached the inten~
sity of the whirling motions of the tornadoes in the jets
2~ diminishes and the tornadoes merge with other portions of
the jet flow, nevertheless the overall flow of each jet
still retains sufficient kinetic energy to penetrate the
blast and to produce pairs of tornadoes such as indicated
at 24b, 24c and 24d in Figure 2. Thus, the merged jet flow
still has a kinetic energy per unit of volume which is greater
than the kinetic energy of the blast. The manner of develop-
ment of these tornadoes in the zone
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of interaction is fully explained in various of the appli-
cations identified herein, and particularly in our Canadian
application 290,246, above identified, and also in our Cana-
dian application 196,097, filed March 27, 1974, issued as
Patent No. 1,059,321 on July 31, 1979.
The system for developing the jets as described
above is enhanced by the employment of jet orifices having
a cross-sectional dimension in the common plane of the jets,
which is greater than in the direction transverse to said
common plane, and preferably the jet orifices are rectangular
in cross section, because this configuration contributes
significantly to the desired development of the pairs of
tornadoes in each jet. It is further to be noted that these
tornadoes are developed in each jet without requiring impinge-
ment of adjvining jets upon each other, and also without
the necessity for the presence of any jet confining sur-
faces positioned at the lateral edges of each jet; and because
of these features of the arrangement of the present invention,
it becomes possible to position the jet orifices at any
desired spacing, provided, of course, that the spacing is
su~ficient to leave a zone or area intermediate to the jets
over the surface of the deflector 14, in which zones the
induced ambient gas or air will develop regions of laminar
flow into which the glass streams are delivered.
The arrangement of the invention as described
above is also characterized by development of the zones
of laminar flow on the surface of a fixed or structural
part of the system, namely the convexly curved Coanda guide
14 and in view of this both the zones of laminar flow and
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also the adjoining portions of the jets are highly stablet
thereby contributing stability to the introduction of the
glass streams into the system.
The kinetic energy of the jet and the blast is
determined by several factors, notably the velocity of the
jet and the blast and also the temperature thereof. The
temperature influences the density of the gases and thus
is also a factor which determines the kinetic energy. Although
in various of the Canadian applications above identified,
for instance in our Canadian application 196,097, above
identified, both the jet and the blast are disclosed as
having temperatures well above room temperature, for instance
a jet temperature of the order of 800C and a blast temperature
of the order of 1580C. For many purposes, it is preferred
to utilize a iet having much lower temperatures, for instance
a temperature approximating ambient or room temperature,
as is fully disclosed in our Canadian application Serial
No. 290,253, filed November 4, 1977.
With the lower jet temperature, it becomes prac-
tical to employ a commonly available source of air for thejet rather than some burner or heater arrangement; and in
addition, the jet velocity may be lowered, even below that
of the blast, and still provide sufEicient kinetic energy
in the jet to penetrate the blast and develop the interac-
2~ tion zone, including the tornadoes utilized in all of theapplications above referred to for effecting attenuation
of the glass stream in the blast.
It is also to be noted that the jet system to
gether with the feed of the glass into the system may be
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utilized by itself for purposes of attenuation, but it is
preEerred to utilize the jet system in combination with
the blast, in ~hich event each glass stream is subjected
to two stages of attenuation, one of which occurs in the
jet system itself, and the second of which occurs in the
toration zone or zone of interaction of the jet with the
blast.
Attention is now directed to Figures 5, 6 and
7 which illustrate somewhat diagrammatically the major com-
ponents of a fiberizing system according to the presentinvention, i.e., the means for developing the blast, the
means for developing the jet, the convex guide element
for deflecting the jet flow and developing the tornadoes
in the jet~ together with the means for introducing the
attenuable material. All of these components are shown
in section in Figure 5 and in Figures 5, 6 and 7 symbols
or legends have been applied to identify certain dimensions
and angles, all of which are referred to in one or another
of the tabulations herebelow. The tables give not only
appropriate ranges for the dimensions and angles but also
indicate typical preferred values.
In considering the symbols and legends, reference
is first made to the bushing 17 and the devices 16 for
the supply of the attenuable material, in connection with
which see Table I just below.
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TABLE I
Symbol Preferred Range
Value
dT 2 1 ~ 5
lT 1 1 ~5
1~ 5 0-~ 10
dR 2 1~ 5
DR 5 1~ 10
With reference to the jet supply and the convexly
curved element 14, see the following table: -
TABLE II
(mm, degree1
Symbol Preferred Range
~'alue
dJ 2 0.5 -~4 . . .-
DJ 3 l~ i~ 4
Y 2 l~ 10 : :-
JJ
YJF 2 ~J~ DJ ~ yJJ
2 : -
~ 2.5 2 ~ 4
dj :
D 45 30~ 0 .
20-~90
JB
The spacing of the glass delivery orifices should
be the same as the spacing of the side-by-side median planes
of the jet orifices. As clearly appears in Figure 6, it
is preferred that each glass supply device be positioned
to deliver a stream of glass S into the zone of laminar
flow overlying curved guide element 14 between adjoining
jets but at a location closer to one of the adjoining jets
than to the other. This assures that the glass stream will
consistently and stably enter the flow of the nearest jet.
With regard to the blast, note the following table~
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TABLE III
(mm)
Symbol Preferred Range
Value
dB 10 5 _~20
In addition to the foregoing dimensions and angles
involved in the major components of the system, certain
interrelationships of those components are also to be noted,
being given in the table just below.
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TABLE IV
(mm~
Symbol Preferred Range
Value
JF 1 -~15
ZJB 20 12 / 30
X 5 0 ~ 20
BF
JF 5 0 - ~ 10
The number of fiberizing centers may run up to
as many as 150, but in a kypical installation where glass
or some similar thermoplastic material is being fiberized,
a bushing having 70 delivery devices or orifices is appro-
priate.
In connection with the operating conditions, it
is first pointed out that the conditions of operating the
system according to the present invention will vary in accor-
dance with a number of factors, for example in accordance
with the characteristics of the material being attenuated.
As above indicated/ the system of the present
invention is capable of use in the attenuation of a wide
range of attenuable materials. In the attenuation of glass
or other inorganic thermoplastic materials, the temperature
of the bushing or supply means will of course vary according
to the particular material being fiberized. The temperature
range for materials of this general type may fall between
about 1400 and 1800C. With a typical glass composition,
the bushing temperature may approximate 1480C.
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The pull rate may run about 20 to 150 kg/hole
per 24 hours, typical values being from about 50 to about
80 kg/hole per 24 hours when fiberizing typical inorganic
thermoplastic materials as referred to in the preceding
paragraph.
Certain values with respect to the jet and blast
are also of significance, as indicated in tables just below
in which the following symbols are used.
T = Temperature
p = Pressure
V = Velocity
~= Density
TABLE V - JET SUPPLY
Symbol Preferred Range
Value
pJ (bar) 2.5 1 ~ 50
TJ (C) 20 ~ 1860
VJ (m/sec) 300 200 ~ 900
(~ V2) (bar) 2.1 0.8 ~ 40
TABLE VI - BLAST
Symbol Preferred Range
Value
pB (m/bar) 95 30 ~ 250
TB (C) 1450 1300~ 1800
VB (m/s) 320 200 - ~550
(~ V2) (bar) 0.2 0.06 -- ~ 0.5
The kinetic energy ratio of the jet to the blast
may typically be 40 to 1.
