Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
Fiber ~ormation from attenuable material by e~tab-
lishing a pair of counter-xotating whirls vr tornadoes,
known as toration, is disclosed in our Canadian Application
No. 196,097. In that known technique, a gaseous blast is
generated and a gaseous jet, known as secondary or carrier
jet, is also generated~ the jet being of smaller cross sec-
tion than the blast, being directed in a path transverse
to the axis of the blast, and having higher kinetic energy
per unit of volume than the blast so that the jet penetrates
the blast. Such a jet penetrating a blast develops a zone
of interaction of the jet and blast, which zone is charac-
terized by the development of a pair of oppositely rotating
tornadoes between which a zone of relatively low pressure
occurs at the blast boundary adjacent to and downstream
of the zone of penetration oE the jet into the blast. In
this known toration technique, a stream of the attenuable
material is delivered to the zone of low pressure, from
which the attenuable material enters the zone of interac-
tion between the jet and blast and is subjected to the hiyh
velocity currents of the whirls or tornadoes, thereby effect-
in~ attenuation of the stream and forming the fiber.
As disclosed in the prior application above re-
ferred to, the stream of attenuable material is delivered
or introduced into the zone of interaction by the placement
of a discharge orifice for the attenuable material at or
substantially at the boundary of the blast. It is a major
objective of the present invention to provide for the separa-
.
.,, ~
tion of the discharge oriElce for the attenuable matcrlal
from the boundary of the blast and at the same time to
provide for such separatic¢n while maintaining stable del.ivery
of the attenuable material into the system. The manner
in which this is accomplished will be developed more fully
herebelow.
In accordance with one important aspect of the
present invention, provision is made for the generation
of a pair of counter-rotating whirls or tornadoes, by estab-
lishing a gaseous flow or jet and by utilizing certain
jet guiding structure or deflector arranged (in the manner
more fully described hereinafter~ to generate a pair of
counter-rotating whirls or tornadoes having therebetween
an area of substantially laminar flow also characterized
by low pressure with consequent pronounced induction of
air. It will be noted that, in accordance with this aspect
of the present invention, the pair of counter-rot¢~ting
tornadoes is gene~ated by guide structure influ~ncing a
gaseous Elow or jek, rather than by the penetration of
a jet inko a blast, as in the ~oration technique disclosed
in the applicatiGn above identified. The action of the
deflector not only develops the pair oE tornadoes but also
provides the substantially laminar flow low pressure area
between the pair of tornadoes, and the present invention
~ 25 contemplates the introduction or delivery of a stream of
; attenuable material, for instance, molten glass, into the
,¢~
,s~.
influence o the induced alr entering the zone or area
of laminar flow formed between the p~ir of counter~-rotating
tornadoes. Thi~ re~ult~ in introducSion o~ She ~tream
of attenuable material into the laminar flow betwaen the
-2a-
;~, ~,,
tornadoes and thence into the influence of the high velocity
currents of the pair oE tornadoes, with consequent attenuation
of the st.ream to form a fiber.
In accordance with another important aspect oE
the present invention, the attenuation technique above
described, including the generation of the oppo~itely ro~at~
ing tornadoes acting on a gaseous jet is used as a first
stage of a two-stage attenuation technique, the second
stage being effected by delivery of the jet and the attenuat-
ing fiber carried thereby transversely into a blast of
larger cross section, the jet still retaining sufficient
kinetic energy to penetrate the blast and develop a zone
of interaction in accordance with the toration technique
described in the above identified applications. This re-
sults in introduction of the preliminarily attenuated f.iber
into the zone of interaction of the jet and the blast,
with consequent further atkenuation of the Eiber.
By the above descrlbed operation, a sin~le ~iber
is Eo.rmed frQm a single-stream of the attenuable material,
notwithstanding the fact that the stream is subjected to
two sequential stages of attenuation, each of which involves
the subjection of a stream or fi~er to the action oE the
high velo~ity currents set up by the two sequential pairs
of tornadoes generated in the jet and in the blast.
--3--
,~.,~
Employment of the technique according to the
invention, ha~ numerou~ distinctive advantage~. In the
~irst place, from the foregoing it will be seen that the
~3a-
.,; ,,~
use of the pair of tornadoes developed by jet guidl~g mean~
as a first stage of the attenuating operation, se~ve~ also
as a means for introduction of the attenuating fiber into
the zone of interaction between the jet and the blast,
i.e. into the torating zone. Thus, this first stage is
in effect utilized as a feed or delivery means in relation
to the toration operation subsequently carried on in the
toration zone between the jet and blast. This use of the
first stage has numerous important advantages. In the
first place such use makes it possible for suhstantial
separation of the several components of the system, namely
the means for generating the blast, the means for generating
the jet and the means for introducing or delivering the
attenuable material into the system.
Separation of the components is in turn advan-
tageous for a number of reasons including particularly
the fact that such separation reduces heat -transfer between
the three components oE the system, in view of which greater
flexibility is posslble ln the maintenance of different
temperatures as between the means for genQrating the blast,
the means for generating the jet and the means for supply-
ing and admitting the attenuable material. In turn, such
reduction in heat transfer between these components makes
possible the use of the system for the production of fibers
from materials, such as hard glassesl which require rela-
tively high temperatures ~o bring them to ~he molten state
or consistency appropriate for attenuation.
The separation oE the components which i~ made
possible according to the present invention, also eliminakes
or reduces the production oE unfiberized or improperly
fiberized particles resulting from sticking of the attenu-
able material on hot surfaces. In consequence, more uni-
formly flberized products are obtainable.
Still further, the e~ployment of the two-stage
system of the present invention, in which the first stage
serves as a means for feeding the attenuable material into
the zone of interaction of the jet and blast, i.e. the
toration zone, is desirable because it provides a means
for stabilizing feed of the attenuable material into the
zone of interaction, notwithstanding the substantial separa-
tion of the supply means for the attenuable material from
the boundary of the blast. Indeed, even with quite sub
stantial separation, the feed of the attenuable material
is stabilized and accurately controlled, which is an impor-
tant factor in pro~iding for uniform fiberlzing in the
zone oE in~eraction, i.e. for uniform toration. Because
the Eirst stage or feeding means utilizes a pair of counter-
rotating tornadoes generated in spaced relation by the
guiding action of elements positioned to influence the
jet, the laminar flow low pressure area between the tornadoes
into which the attenuable material is delivered, results
in accurate feed of the stream of attenuable material from
that area into the region between the counter-rotating
tornadoes, and this accuracy is maintained even in the
event of some mi.salignment of the supply orifice for the
attenuable material with relation to the jet.
In aon~equence of ~hi~ "au~omatic" compen~atlon
for inaccuracies in the point o~ supply of the attenuable
ma~erial, high precision machlning of certain parts is no
longer necessary, for instance parts associated with the
feed of a stream of molten glass. Such high precision of
machining is not readily compatible with the very high
temperatures encountered in the handling of molten glass,
and this is particularly so where very hard glasses or
certain other materials such as slags or certain rocks are
being fiberized~
It is also noted that as an alternative, a slot
may be employed for admission of the attenuable material
in the general manner disclosed in Figures 12 and 12A, of
the prior Canadian applications above referred to, in which
event, supplementary secondary jets would be located one
beyond each end of the slot.
The techni~ue of the present invention is al~o
o advantage b~cause it may be employed in connection with
a wide variety of attenuable materials, including not only
various mineral materials as mentioned above, but even
certain organic materials which may be attenuable, such
as polystyrene, polypropylene, polycarbonate and polyamides.
--6--
In the two-stage a~tenuat:ion techni~ue above
referred to, the invention al50 contemplate~ employment
of certain novel interrelated conditions of operation of
the gaseous jet and gaseous blast, providing improved effi
ciency with respect to power or energy consumption. Thus, ~he
invention contemplates establishment of a torating zone
-6a-
of inte~actLon between the jet and blast by employment of
lower jet velocities and temperatures than heretofore used
in establishing the zone of interaction between a jet and
blast. By employing lower jet temperatures tfor instance
a temperature approximating ambient or room temperature),
consumption of energy to heat -the jet is eliminated andl
in addition, the gas of the jet is increased in density.
In consequence, the kinetic energy level of the jet required
for penetration of the jet into the blast is provided at
lower jet velocities, thereby effecting further power econo-
mies. When employin~ such lower jet temperatures, it is
even possible to employ jet velocities well below the velo-
city of the blast and still maintain the kinetic energy
~evel of the iet sufficiently high to provide the desired
penetration of the jet into the blast.
The lower iet velocities are still fuxther of
advantage in the two-stage attenuation technique herein
disclosed because in the first stage of attenuation, in
which the stream of attenuable materLal is delivered to
the jet, the lower jet velocities and temperatures assist
in avoiding fragmentation of the stream of attenuable matexial.
Although, for most purposes, it is contemplated
accordin~ to the technique of the present invention~ that
the fiberization of the attenuable material be effected
in two stages .in the manner generally cle~cribed above, it
i5 to be noted that fo~ some purpo~es the attenuable
material may be subjected to only the first stage of the
fiberization described, i~e. may be subjected to only that
stage of the ~iberization occurring as a result of the
7a-
19
feed oE th~ att~rluclble ma~erial into khe ~one b~tween
the counter-rotating tornadoes developed by the action
of guide elements employ~d with the jf't. ~n this event,
the blast, i.e. the torating blast, and the penetration
of the jet into the blast may be dispensed with, thereby
simplifying the equipment set up.
Altho~gh the technique of the present invention
is applicable to any attenuable material, it is particularly
adapted to the attenuation of thermoplastic materials and
especially thermoplastic mineral materials such as glass
and similar compositions which are heated to the molten
state or the molten consistency appropriate for attenuation.
The embodiment illustrated and described hereinafter is
particularly appropriate for use in the attenuation of
glass or similar compositions, and where references are
made to glass, un~ess otherwise indicated by the con~ext,
it is to be understood that any appropriate attenuable
material may be used.
In summary o the above, thereore, the present in-
vention ma~ be broadly seen as providing a method for ~orm-
ing fibers from attenuable mater:ial, comprising generating
a gaseous jet having a substantially laminar flow central
portion and having at opposite lateral sides a pair of
counter-rotating tornadoes of diameter progressivel~ in-
creasing and ultimately merging downstream of the portion of
laminar flow, and delivering a stream of attenuable material
to the portion of laminar ~low between the tornadoes upstream
of the region of merging.
The above method may be carried out by an apparatus
for forming fibers from attenuable material comprising means
for generating a gaseous flow, means for establishing a pair
of spaced counter-rotating tornadoes and an intermediate
.;,, ~.
/ , ~ 8 -
l~minar f:l.ow ~re~a i.n t.h~ ~aseou~ ~'low w:i-th the l~mln;,l:e
~low area exposed at one sldc of -the yaseous flow ~nd
with the tornadoe~ inc.reasing in diameter and ultimately
merging downstream of the laminar ~rea, and means for
delivering a stream of attenuable material into the in-
fluence of the gaseous flow in a region along the path
thereof in the exposed laminar flow area between the
tornadoes.
How th.e foregoing features and advantages are
. attained will appear more. fully from, th.e.following des~
cription referring to the accompanying drawings which
illustr~te one prefe.rred embodiment of equipment according
to the invention and also which'diagrammatically represent
significant portions of the action of the jet, blast and
of the attenuating operation itself. In the drawings -
Flgure 1 is an outline overall elevational yiewwith a, few parts shown in vertical section showing the
,. i
.~
pg/ - 8A -
gene~al ar~ancJement oE ~he major components o~ an equipment
according to the technigue o the present invention.
Figure 2 is an enlar~ed vertical sectional view
of the components provided at one of the fiberizing center~,
this view being taken as indicated by the section line 2-
2 on Figure 4;
Figure 3 is a further enlarged fragmentary in-
verted plan view of some of the jet and glass orifices,
this view being taken as indicated by the line 3-3 on Figure
~0 2;
Figure 4 is an elevational view o portions of
; the equipment shown in Figures 1 and 2 and taken from the
right of Figure ~;
,, Figure 5 is a plan view taken generally as ln-
dicated by the line 5-5 applied to F,igure 4;
Figure 6 is an enlarged perspective view of a
jet manifold box employed in the equipment shown in Figures
1 to 5;
Figure 7 is a perspective diagrammatic view il-
lustrating the operation of the method and equipment accord-
ing to the present invention;
.a~
,
Figure 8 i~ a cro~s sectional fragmentary c~nd
enlarged view of the equipment vlew~d as in E'igur~ 2~ ~nd
illustrating certain phases of the acti~ity of the blast
-~a-
and jet 1n effecting attenuation of the glas~ being del1v-
ered from the orifice at the top of the Eigure;
Figure 9 is a plan view of several jets and of
portions of the blast shown in Figure 8, but omitting the
glass feed and glass fibers being formed;
Figure 10 is a transverse diagram through portions
oE several adjacent jets, and illustrating directions of
rotation of certain pairs of the counter-rotating tornadoes;
Figure 11 is a fragmentary sectional view of the
major components, particularly illustrating certain dimen-
sions to be taken into account in establishing operating
conditions in accordance with the preferred practice of
the present invention;
Figure lla is a fragmentary sect:ional view showing
the spaclng between a pair of adjacent jet ori~ices; and
Figure llb is a transverse sectional view through
a portion of the d01ivery means for the attenuable material.
In connection with the drawings, reference is
first made to Figure 1 which shows somewhat schematically
a typical overall arrangement of equipment adapted to carry
out the technique of the present invention. Toward the
left in Figure 1 there is shown in outline at 15 a portion
of a burner or blast producing structure having an associa-
ted nozzle 16 with a discharge aperture 17 of substantial
--10 -
width ~o a~ to deliver a blask 18 with whlch a plural:L~y
of fiberizing centers may be associated. A supply line
for a gaseous fluid under pressure is indicated in Figure
l at l9 and this supply line is connected to jet manifold
boxes 20 which cooper2te in supplying the jet 1uid to and
through jet orifices, one of which appears at 21.
A bushing 22 associated with a forehearth or other
appropriate glass supply means indicated at 23 is provided
with glass orifice means indicated at 24, and the stream
of glass is delivered into the flow of the jet to be described
hereinafter and is carried downwardly to the zone of inter-
action in the blast 18. As will be explained, fiberization
occurs in the jet and also in the bla~t, and as the blast
delivers the fibers toward the right as viewed in Flgure
l, a fiber blanket indicated at 25 is laid down upon a per-
forated traveling conveyor or belt 26, having a suction
box 27 below the upper run of the conveyor, the hox 27
: connecting with a suction Ean diagrammatically indicated
at 28 to assist in laying down the desired ~iber blanket
on the per~orated conveyor 26.
Various of the ~iberization parts are shown in
greate~ detail in Figures 2 to 6 inclusive, to which refer-
ence i5 now made.
The bla~t an~ jek ~ruckures are adv~rlt~geou~ly
adjustably mounted with respect to .supporking structure
such as diagrammatically indicated at 29, so tha-t the rela-
:~ tive vertical positioning of the blast and the jet may
-lla-
be aLtered, and preferably also so that the ~elative po~i~
tioning of these parks may be ad~usted in a direction up-
stream and downstream of khe blast 18.
As seen particularly in Figures 4 and 5, the blast
nozzle 16 is of substantial width, thereby providing for
a wide blast delivery orifice 17. The bushing 22 for the
supply of glass preferably also has substantial dimension
in the direction perpendicular to the plane of Figure 2
in order to provide for the supply of glass to a multipli-
city of the glass delivery devices 24 as clearly appears
in Figure 4. Each of the delivery devicPs 24 has a meter-
ing orifice 24a and pref~rably also an elongated reservoir
or cup downstream of the métering orifice as indicated at
24b (see particularly Figures 2 and 3~. The reservoirs
or cups 24b are desirably elongated in the plane of the
fiberizing center, i.e., the plane containing the glass
supply device 24 and its associated jet orlfice 21.
The j~t orifices 21 are provided in the front
edge wall o~ each oE a series of manifold boxes 20, four
such boxes being provided in the equipment illustrated,
and these boxes are mounted by means of mounting rods, in-
cluding guide rods 30,30 mounted on the supporting structure
29 and which extend throughout the length of the bushing
22 and which pass through apertures 3~ (see Figure 2 and
Figure 6) on the mounting lugs 32 provided at each end of
each of the jet manifold ~oxe~ 20. Thus~ the several jet
manifold boxes are mounted with freedom for ~hifting move-
ment either to the right or left as viewed in Figures 4
and 5.
-12
~,., j
The posLtion~ oE the jet boxes on the mountinq
guide rods 30 are determined by means of additional rods
33, 34, 35 and 36, each of which is threaded at its inner
end, to cooperate with a threaded aperture in one of the
lugs 32 of the guide boxes, one such threaded aperture ap-
pearing at 37 in Figure 6. Each of the rods 33 to 36 i5
provided with a notched end 38 by means of which it may
be rotated, and these adjustable rods are axially fixed~
so that rotation thereof imparts a lateral adjustment or
shifting movement to the a~sociated jet manifold box 20.
By this arrangement, the relative positions of
the jet orifices 21 with respect to the glass orifice devices
24 may be adjusted, and this may be used to compensate for
thermal expansion and contraction of parts. Having the
jet orifices distributed between a number of jet manifold
boxes (four in the embodimert illustrated) provides for
substantial alignment of the jet orifices with the glass
orifices on lines paralleling the flow o~ the blast. Al-
though the alignment may not he absolute, ~his is not nece~-
sary with equipment o~ the kind herein illustrated in which
the glass streams are delivered into the substantially
laminar flow zones between the tornadoes, such as 44b shown
in Figure 7, since as above brought out, delivery o~ the
glass streams into these zones results in automatic com- -
pensation for slight inaccuracies in the relative positions
of the jet and glass orifices.
Each of the boxes 20 is connected with the jet
fluid supply line 19 by means of a pair of flexible connections
-13
39 which permit adjustment o~ the po~itiorl Oe th~ hoxe~
20 independently of the supply line 1~.
As hereinabove indicated, it is contemplated ac-
cording to the present invention that the jets delivered
from the jet orifices 21 be subjected to the guiding action
of certain elements or devices which cooperate with the
jets in generating the desired pairs of counter-rotating
whirls or tornadoes which are utili~ed for at lea~t the
preliminary attenuation of the streams o attenuable material
and also for purposes of feed of the partially attenuated
filaments into the zone of interaction provided by pene-
tration of the jets into the blast~ i.e. into the toration
zones. For the purpose of developing the counter-rotating
pairs of tornadoes, the present invention contemplates the
utilization of a guiding means, advantageously a common
- deflector plate 40 associated with a group of the jet
orifices. Where the jets are subdivided into groupsl and
each group associated with a manifold box such ag indicated
at 20, each such box desirably carries a de1ector plate
40. As seen particularly in Figures 7 and 8, the guide
or deflector plate is desiLably formed as a bent plate 9
one portion of which overlies and is secured to the jet
manifold box and the other portion of which has a free edge
41 lying in a position in the path of flow or core of the
jets delivered from the jet orifice 21, advantageously along
a line intersecting the axes of the jet orifices.
-14-
As :L3 graphlcally i:Llu~traked, par~lcularly in
Flgure 7, thi~ po~ition of the de.flector plate 40 and its
edge 41 results ln impingement of each vf the jets upon
-14a-
the underslde o ~he p1ate 40 with con~quent spreadlng
of the jets. Thus, in Figure 7, the flow of our of the
jets oriyinating from oriEices a, b, c and d is ~hown, and
it will be seen that as the edge 41 of the plate is approached,
each of the jets spreads làterally.
It is contemplated according to the invention
that the jet orifices 21 be placed sufficiently close to
each other and also that the deflector or guiding means
be arranged so that upon lateral spreading, the adjacent
or adjoining jets wlll impinge upon each other in the region
vf the edge 41 of the deflector plate. Preferably, the
.~ adjacent jets impinge upon each other at or close to the
free edge 41 of the guide plate 40 as is shown in Figure
7. This results in the generation of pairs of counter-
rotating whirls or tornadoes which are indicated in Figure
7 in association with each of the three jets delivered from
: the orifices a, b and c.
In anal~zing the formatiorl oE these tornadoes,
particular reference is made to those associated with the
jet originating from oriEice b in Figure 7. Tbus, it will
be seen that tornadoes 42b and 43b, are generated and that
these two tornadoes have their apices originating substan-
tially at the edge 41 of the deflector 40 at opposite sides
of the jet at the zone in which the spreading jet impinges
upon the adjacent ~preading jets de~ ered Erom orlfiaes
a and c. The tornadoes 42b and 43b are oppositely rotating
as is indicated particularly in Figure 10, and the tornadoes
enlarge as they progress, until they meet at a point spaced
downstream from the edge 41 o~ the deflector. These tornadoes
-15a-
42b and 43b a].~o have currents in the down~eam directlon,
as will be seen.
Because Oe the spacing of the apices or points
of generation of the tornadoes 42b and 43b and because of
the progressive enlargement of those tornadoes, a generally
triangular zone 44b intervenes be~ween the tornadoes and
the edge 41 of the deflector plate, and this triangular
zone is of relatively low pressure and is subjected to ex-
tensive inflow of induced air, but the flow in this zone
: 10 is substantially laminar. This is the zone into which the .:
stream of molten glass or other attenuable material is intro~
duced into the system, and because of the character of this
triangular laminar zone the stream of glass is not frag-
mented but is advanced as a single attenuating stream into
the region between the pair of tornadoes.
.~ Attention is now called to tha fact that the direc-
tions of rotation of the currents in the tornadoe~ 42b and
43b are opposite, being clockwise .Eor tornado 42b and counter
clockwise for tornado 43b as viewed in Figure 7. Thus,
the currents in these two tornadoes approach each other
at the upper side thereof and then flow downwardly toward
the central or laminar zone 44b~
The directions of rotation just referred to are
further indicated by arrows or the tornadoes 45a and 46a
-16-
,
'~ ~
in connec~lon with the corre~ponding palr of tornadoe~ a0~0-
ciated with the jet delivered from the ori~ice a. It will
be understood that in the illustra-tion of the jet flow origi~
nating from orifice a, the flow has heen shown as cut off
-16a-
. ,,
19
or sectioned adjacent to the clownstrelam en~ oE th~ zone
of laminar flow 44a, i.e. adjacen~ to the ~one in which
the pair of tornadoes have been enlarged and commence the
mutual merging which occurs as the jet flow proceeds. With
the illustration just referred to, ît further clearly appears
that the jet flow originating from orifice ~ not only in-
cludes the pair of tornadoes 45a and 46a but also includes
another pair of tornadoes 47a and 48a, the directions of
rotation of which are also opposite to each other r as shown
in Figures 7 and 10, but in this case, the tornado 47a at
the left, as viewed in Figure 7, rotates in a counter clock-
wise direction, whereas the tornado 48a at the right rotates
in the clockwise direction. It will be understood that
similar duplicate pairs of tornadoes are generated by and
associated with each of the jets. The origin of generation
of the lower pair is somewhat diEferent than the origin
of generation of the upper pair as will be explained here-
inafter with more particular reference to Figure 8.
St111 referring to Figure 7, as the flow proceed~
from the plane in which the tornadoes are illustrated for
the jet delivered from orifice a, all four of the tornadoes
tend to merge and reform a more generalized jet Elow and
this is indicated in Figur~ 7 by a section 49c, representing
a downstream section of the jet flow originating from orifice
c. As will be seen, the whirling motions of the tornadoes
-17-
are diminl~hing in inten~ity and ~he entire ~low, inaluding
the laminar flow of the central zone oE the jet, intermi.x
with each other in the region indicated at 49c, and there-
after the jet progresses downwardly toward the blast which
is indicated at 18 in Figure 7 and referred to more fully
hereinafter.
-17a-
In the illustratlon of Figure 7 it will be~ und~r-
stood that for the sake of clarity, the showing of the various
portions of the jet flow is somewhat schematic. For instance,
in a zone spaced somewhat downstream of the points of origin,
s the pairs of tornadoes originating in one jet appear in
the figure as being somewhat separated from the pair of
tornadoes originating in adjoining jets, whereas, in fack,
the tornadoes o~ adjoining jets would be substantially con-
ti~uous.
Turning now to the illustration in Figure 8, it
is assumed that the fiberizing center there shown is the
center originating at the jet orifice b of Figure 7. The
tornado 43b is also there shown, as is the .intervening laminar
zone 44b. The lower pair of tornadoes originate in the
region within or under the deflector plate 40, Figure 8
being a sectional view showing only the lower tornado 48b,
which originates behind the zone 44b. The direction of rota-
tion of these lower tornadoes originated as a result of
the combined action of the jet on the unders.ide o~ the plake
40, toyether with induced air currents joining the jet stream,
and it is here noted that the currents in the lower pair
of tornadoes are of lesser intensity or velocity than the
currents in the upper pair. Moreover, the direction of
the currents flowing in the tornadoes of the upper pair
has a dominate influence upon the act.ion of the system when
the str~am of attenuable material is introduced first into
the laminar zone and then into the jet flow downstream of
the point where the tornadoes merge.
-18-
Because of the je~ f:low in the lam1nar zone and
in the pairs of tornadoes, particularly the upper pair of
each group, the introduction of the streaTn of attenuable
material, which is indicated in Figure 7 at S for the fiber-
izing center including the jet orifice b, results in the
progression of ~he stream into the laminar 10w of the
central zone. This carries the stream into the zone of
high velocity lying between the pairs of tornadoes and,
in consequence, the stream is attenuated as is shown in
Figure 7. It is found that this attenuation occurs sub-
stantially within a planar zone indicated in Figure 7 at
P. The action of the pairs of tornadoes causes a whipping
of the attenuated fiber substantially within the planar
zone P, so that -this attenuation does not resu~t in pro-
jection of the fibers being formed laterally toward the
adjoining jets.
Fu~ther jet flow causes the jet, together with
the attenuating fiber carried thereby, to penetrate the
upper boundary of the blast 18, the jet Elow still retaining
sufficient kinetic energy to effect such penetration of
the blast, and thereby initiate a second phase of fiber-
ization which proceeds or is effected, in accordance with
the principles fully explained in the prior Canadian applications
referred to above. Indeed, in the r~gion of penetration
of the jets into the blast, the flow and velocity of each
jet is still sufficiently concentrated near the center of each
--19--
jet so that ~ach jet acts lndividually to d~velop a zone o~
in~erac~ion in the blast. Thus, from Figure 7 it will be noted
that in the zone of inkeractlon, i.e~ in the toration zone,
a pair of oppositely rotating whirls or tornadoes indicated
-19a-
at TT, are yenerated, thereby developing the currents whlch
cause further attenuat:ion of the Eiber being fo~med. The
fiber is thereafter carried by the combined flow of the
jet and blast to a suitable collection means~ for instance
a travelling perforated conveyor such as indicated diagram-
matically at 26 in Figure 1.
As will be understood, both in the laminar zone
adjacent to tlle edge of the deflector and also as the jet
flow progresses downstream, air is induced, and this induc-
tion of air is clearly indicated by arrows applied to the
jet flow in Figure 7. Such induction of air currents is
also clearly indicated in Figure 8.
Having in mind the foregoing description of the
general nature of the equipment and operation contemplated
according to the present invention, attention is now called
to certain permissible variations and ranges of operating
conditions which may be employed.
First wlth regard to the relative positioning
of the jet orificeæ and the guiding or deflecting means,
such as the guiding plate 40, it is contemplated that the
arrangement of the jets and the guiding plate should provide
for spreading of the jets so that adjacent jets impinge
upon each other substantially at the edge of the guide plates.
-20-
I l~hl~
This is the condition illustrated in E'iyure 7 an~ it will
be noted that with this arrange~ent, the points of origin
or the apices of the upper pairs of tornadoes are at the
edge 41 of the guide plate 40.
-~Oa-
The jets and the guid~ plate may be arranged so
that the jets impinge upon each other at points somewhat
upstream or downstream of the edge of the guide plate, but
it is preferred that th~ impingement of adjacent jets upon
each other be maintained quite close to, but not necessarily
precisely on, the edge of the plate, because in this condi-
tion, maximum stability oÇ the tornadoes is attained, with
consequent maximum stability of the intervening laminar
zone of the jet. In turnt the stability of the laminar
zone is important in the stabilization of the glass feed
into the system.
If the point of impingement of adjacent jets is
spaced appreciably downstream of the edge of the guide plate,
the tornadoes become unstable because their apices originate
in free space rather than at the edge of the plate. When
the apices of the tornadoes originate in free space, they
are subject to fluctuations by stray gas currents and in
consequence tend to shift in position; but if the apices
originate at or substantially at the edge of the deEleator
plate they are les~ ~ensitive ko stray currents and, indeed
; appear to "attach" themselves to the edge of the plate in
a stable position.
On the other hand, if the adjacent jets impinge
upon each other at a point spaced appreciably upstream of
the edge of the guide plate, the formation of the tornadoes
is impaired because the guide plate itself prevents proper
formation of the tornadoes.
-21-
It is also of impor~ance in providing for genera-
tion of the upper pair of torrladoes at the edge 41 of the
guide plate, that the edge 41 be located ~t or approximately
at the central axis of the jet. If the edge of the guide
plate is raised substantially, the deflection is corres-
pondingly diminished or even eliminated, in whiGh event
no tornadoes will be generated. On the other hand, if the
edge of the deflector is located excessively low, for in-
stance below the lower boundary of the jet, there is a ten-
dency for the tornadoes tc diminish in their organization
and provide only for uniform or parallel flow throughout
the entire section of the jet, rather than for the desired
higher velocity helical or vortical flow of the tornadoes.
The generation of the tornadoes under the most
favorable conditions, i.e. under the conditions in which
the apices are "attached" to the edge of the deflector,
produces the m~st stable tornadoes and thus also the most
stable operating conditions with respect to the feed of
the glass qtream and it~ attenuation in the planar æone
P above described.
In connection with -the advantages of the technique
of the present invention, it is to be noted that the tech-
nique is capable of producing fibers of a wide range of fiber
diameter, even fibers of smaller diameter than those produced
by the toration technique of the Canadian applications above
-22-
Ldentified. However, of ~pecial lmpo~tance and signlElcan~e
is the fact that the technique of the present invention
is capable of producing fibers of a given diameter at a
substantially higher "pull rate" than is possible with the
toration technique of the Canadian applications fully iden-
tified above. The pull rate here referred to ls the rate
at which the flber may be formed from a given orifice or
supply means for the attenuable material. In accordance
with the technique of the present invention, the pull rate
may even be as high as lS0 kg/hole per 24 hours. This and
other operational factors will be referred to again here-
inafter with particular reference to Figures 11, lla and
llb and the related tabulated information given in the
specification herebelow.
As above indicated, the first phase or stage of
the attenuation technique of the present invention may i~
dQsired be employed independently of the secon~ or toration
stage, and this first stage, alkhough not capable of pro-
ducing fibers as fine as those produced when both stages
are used, does produce fibers that are fine enough for
certain uses and are capable oE being produced at a rela-
tively high pull rate.
Turning now to Figures 11, lla and llb and also
to the information tabulated herebelow, i~ is first pointed
out that -the representation of the various components of
-23-
~ ,.
the ~y~tem, particularly in Figure 11, is giv~n in a mann~r
to :Eacilitate explanation of the ranges of dim~nsions and
angles, and does not necessarily illustrate the preferred
: values in all of the ranges.
-23a-
;''~,
Fi~ure 11 :illu3trates the three major c~mporJent~,
i.e~ the means for developing th~ blas~, the m~ans Eor d~ve~
loping the jet, and the means for introduclng the attenuable
material, each of these three mean~ being shown in section
in the same general manner as in Figures 2 and 8, but in
Figure 11 symbols or legends have been applied to identify
certain dime~sions and angles, all of which are r~ferred
to in one or another of the tabulations herebelow~ 50me
of these symbols or legends appear .in Figures lla and llb.
First, with reference to the bushing 22 for the
supply of the attenuable material, see the following table:
TABLE I
(mm)
S~mbol Preferred Range
~alue
dT 2 1~ 5
T 1 1------_------~5
lR 5 o ~ 10
dR 2 1 ~ 5
DR 5 1-------~10
With reference to the jet supply and the deflector,
see the following table:
-24-
TP.13hE I -
(mm, dec~
Preferred
Symbol Value Range
d~ 2 0.5- ~ 4
lJ 7
Y~ Close to lower about 3~-~about 4
end of range
lD 4 2 ---------~ lO
lJD 0 ~-0006~ ~1
_~ 45 35 -~ 55
JD
JB 10 0 ~ 45
JD 3 2 ~ 5
JD 3 2 --~ 5
In connection with the values indicated for l~D
it is pointed out that zero value represents the position
- of the deElector in which the lowermost portion o~ the free
edge of the deflector lies on the axes of the jets, a nega-
tive value for lJD representing a position o.~ the deflector
above the jet axes.
In connection with the angle identified above
as ~JD~ it is to be noted that downstream of the edge of
the deflector, the jet spreads or enlarges t as will be evident
from Figures l, 2 and 80 However, the angle of this
spreading is not the same as the angle represented by the
symbol ~ 3D~ because the deflector causes the jet to alter its
path and also influences the extent to which the jet spreads.
-25-
With rega~d to the bla~, not~ the ollowing table:
TABLE III
-
Symbol Preferred Range
Value
B 10 5 --~32~
In addition to the ~oregoing dimensions and angles
involved in the three major components o~ the system, certain
interrelationships of those components are also to be noted,
being given in the table just below.
TABLE IV
(mm, degree)
Symbol Preferred Range
Value
JF 8 3---------~15
JB 17 6~ 30
XBJ -5 -12~ 13
JF 5 3 ________~ ~
DB 45 35 ~ 55
In connection with the symbol XBJ, it will be noted that
in the illustration of Figure 11, XBJ is indicated at a
negative value, i.e. with the blast nozzle in a position
(in relation to the direction of flow of the blast) which
is upstream of the position of the jet.
-26-
As indLczlted hereinabove, it is con~emplaked according
to the present invenkion that the carrier or secondary jets
be placed suf f iciently close to each other so that they
-26a-
. ~
.~Y
impinge upon each other in order ko develop the palrs of
tornadoes ln each carriar jet. Any convenient number of
fiberizing centers may be established, each center compris-
ing a delivery device for the attenuable material and an
associated jet, and since each carrier jet must impinge
upon another jet at aach side thereof 9 it will be seen that
the number of jets must include two more than the total
number of delivery means for the attenualbeble material,
the two "extra" jets being positioned at the opposite ends
of the series of jets.
The number of fiberizing centers may run up to
as many as 150, but in a typical installation where glass
or some simllar thermoplastic material is being fiberized,
a bushing having 7Q delivery devices or orifices is appro-
priate. In such a case, there would necessarily be 72 jets.
.,
In connection with the operating conditions, itis first pointed out that the conditions o~ operatlrlg the
system accorcling to the presen~ Lnvention will vary in
accordance with a number of factors, for example in accor-
dance with the characteristics of the material being atten-
uated.
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 a~tenuation of glass
or other inorganic thermoplastic materials, the temperature
of the bushing or supply means will oE 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 14~0C.
-27a-
,, :~ 1,
The pull rate may run from about 20 to 150 kg/hole
per 24 hours, typical values being Erom about 50 to about
80 kg/hole per 24 hours.
Certain values with respect to the jet and blast
are also of significance, as indicated in tables just below
in which the ollowing symbols are used.
T = Temperature
p = Pressure
V = Velocity
~C~= Density
TABLE V - JET SUPPLY
. .
Symbol PreEerred Range
Value
pJ (bar) 2.5 1 ~----------~ 4
T~ (C) 20 ~ 1500
VJ (m/s) 330 200~ 900
V ) (bar) 2.1 0.8 ~ 3.5
TABLE VI - BLAST
Symbol PreEerred Range
2g Value
pB (mbar) 95 30 ~ 250
TB (C) 1450 1350 ~ 1800
VB (m/s) 320 200 ~ 550
V ) (bar) 0.~ 0.06 ~ 0.5
-28-
W:Lth regard to the jet an-3 blast, it should be
kept in mind that it is contemplated according to the present
invention that the deflected jet may be utilized alone ~or
attenuation of certain materials, without the employment
of the blast in combination with the jet~ It i8 also to
be kept in mind that where both the jet and blast are employed,
-2~a
it is contemplated that the jet shall have a cro~s sectLon
small~r than ~hat of the blast an~ shall penetrate the blast
in order to develop a zone of interaction in which the secondary
or toration phase of the attenuation will be effe~ted.
For this purpose, the jet must have greater kinetic energy
than the blast, per unit of volume of the jet and blast
in the operational area thereof. The jet may have kinetic
energy of from 1.60 to 60 times that of the hlast, a typical
ratio being 10 to 1. Thus, in terms of the kinetic energy
values given in Tables V and VI above: ~ 2)J = 10
~ V )B
EXAMPLE
In equipment of the kind illustrated in Figures
1 to 6 and having 70 fiberizing centers, a glass of the
following composition was attenuated.
SiO2 63.00
23 0.30
2 3 2~95
CaO 7 35
MgO 3.10
Na20 14.10
K20 0.80
B203 5.90
BaO 2.50
~Parts by weight)
_~9_
~`~
~. ~'f~
The bushiny temperature was about 1500C and the
jet and blast temperature were respectively about 20C and
1500C. The ratio of the kinetic energy of the jet to the
blast was about 10 to 1. The pul~ rate was 55 ky/hole per
24 hours.
The fiber diameter after both stages of at-tenuation
averaged about 6 microns.
: -30
,, .
