CA1121119A - Fiber formation by use of high velocity gas blast attenuation - Google Patents

Abstract

FIBER FORMATION BY USE OF HIGH
VELOCITY GAS BLAST ATTENUATION

Abstract of the Disclosure Method, and equipment are disclosed for forming fibers from attenuable material, such as molten glass, by the use of high velocity whirling gas currents or tornadoes. Attenuation is preferably effected in two stages, each of which utilizes a pair of high velocity whirling currents or tornadoes, with the gases in the two tornadoes of each pair turning in opposite directions and and with the attenuable material introduced into a zone between the tornadoes of each pair.

Description

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-.

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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.

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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.

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-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 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.

~,., 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 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.

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 , '~ ~

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-. ,, 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 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.

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 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.

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.

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 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 ~ ,.

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:

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.

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.

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 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 ,, .

Claims (30)

The embodiments of the invention in which an ex-clusive property or privilege is claimed are defined as follows:

1. A method for forming fibers from attenuable material comprising generating a gaseous flow, establishing a pair of spaced counter-rotating tornadoes and an inter-mediate laminar flow area in said gaseous flow with the laminar flow area exposed transversely at one side of the gaseous flow and with the tornadoes increasing in diameter and ultimately merging in the downstream direction of flow of the laminar area, and delivering a stream of attenuable material into the influence of the gaseous flow in a region along the path thereof in said exposed laminar flow area between said tornadoes.

2. A method as defined in Claim 1 and further including directing a gaseous blast of larger cross section than said gaseous flow in a path intercepting said gaseous flow .

3. A method for forming fibers from attenuable material, comprising generating a gaseous jet having a sub-stantially laminar flow central portion and having at oppo-site lateral sides a pair of counter-rotating tornadoes of diameter progressively increasing and ultimately merging downstream of the portion of laminar flow, and delivering a stream of attenuable material to the portion of laminar flow between said tornadoes upstream of the region of merg-ing. .

4. A method for forming fibers from attenuable material, coprising generating a gaseous jet having a sub-stantially laminar flow central portion and having at oppo-site lateral sides a pair of tornadoes of diameter progress sively increasing and ultimately merging downstream of the portion of laminar flow and delivering a stream of atten-usable material to the portion of laminar flow between said tornadoes upstream of the region of merging, the laminar portion of the jet having a horizontal component of travel, the stream of material being delivered downwardly to the portion of laminar flow, and the tornadoes of said pair having opposite helical motion with downward components at the adjacent sides thereof and with axial components in a direction downstream of the laminar flow of said por-tion.

5. A method for forming fibers from attenuable material, comprising generating a gaseous jet having a sub-stantially laminar flow portion and having at opposite lateral sides a pair of tornadoes of diameter progressively increas-ing and ultimately merging downstream of the portion of laminar flow, and deliveriny a stream of attenuable material to the portion of laminar flow at one side thereof between said tornadoes upstream of the region of merging, the tor-nadoes of said pair having opposte helical motion, with converginy components of motion at the sides of the jet to which the stream of material is delivered.

6. A method for forming fibers from attenuable material, comprising generating a gaseous flow having por-tions of different flow characteristics in different por-tions thereof including a portion of substantially laminar flow with a pair of counter rotating tornadoes at opposite lateral sides of the portion of laminar flow, which tor-nadoes progressively increase in diameter and which ulti-mately merge downstream of the laminar portion, and deliver-ing a stream of attenuable material to the laminar portion between said tornadoes upstream of the region of merging.

7. A method for forming fibers from attenuable material, comprising generating a gaseous flow having por-tions of different flow characteristics in different por-tions thereof including a portion of substantially laminar flow with a pair of tornadoes at opposite lateral sides thereof, which tornadoes progressively increase in diameter and which ultimately merge downstream of the laminar por-tion, and delivering a stream of attenuable material to the laminar portion at one side thereof between said tor-nadoes upstream of the region of merging, the tornadoes of said pair having opposite helical motion, with converging components of motion at that side of the laminar portion to which the stream of material is delivered.

8. A process for forming fibers from attenuable material characterized by generating a gaseous flow having portions of different flow characteristics in different portions thereof including pairs of side by side spaced tornadoes with a zone of laminar flow between the tornadoes of each pair, with the tornadoes increasing in diameter and merging downstream of the zone of laminar flow, and delivering a stream of attenuable material to one side of each zone of laminar flow, the tornadoes of each pair having opposite helical motion, with converging components of motion at that side of the zone of laminar flow to which the stream of attenuable material is delivered.

9. A method for forming fibers from attenuable ma-terial, comprising generating a gaseous jet having a substan-tially laminar flow central portion and having at opposite lateral sides a pair of counter-rotating tornadoes of diameter progressively increasing and ultimately merging downstream of the portion of laminar flow, generating a gaseous blast in a path intercepting the jet downstream of the region of merging of the tornadoes, the cross section of the merged jet flow being smaller than that of the blast and the merged jet flow being of greater kinetic energy than the blast so that the jet penetrates the blast and produces a zone of interaction of the jet and blast, and delivering a stream of attenuable material to the portion of laminar flow between said tornadoes upstream of the region of merging, thereby providing preliminary attenuation in the jet flow and further providing additional attenuation in said zone of interaction by toration.

10. A method for forming fibers from attenuable material, comprising generating a gaseous jet having a substan-tially laminar flow central portion and having at opposite lateral sides a pair of tornadoes of diameter progressively increasing and ultimately merging downstream of the portion of laminar flow, generating a gaseous blast in a path inter-cepting the jet downstream of the region of merging of the tornadoes, the cross section of the merged jet flow being smaller than that of the blast and the merged jet flow being of greater kinetic energy per unit of volume than the blast so that the jet penetrates the blast and produces a zone of interaction of the jet and blast, and delivering a stream of attenuable material to the jet at one side thereof between said tornadoes upstream of the region of merging of the tornadoes, the tornadoes of said pair having opposite helical motion with converging components of motion at the side of the jet to which the stream of material is delivered, thereby providing preliminary attenua-tion in the jet flow and further providing additional attenua-tion in said zone of interaction by toration.

11. A method of forming fibers from attenuable ma-terial comprising establishing a series of spaced gaseous jets directed in side by side paths, deflecting the jets from said paths to alter the paths thereof and to cause lateral spreading of the jets, the jets being sufficiently close to each other to provide for impingement of adjoining deflected jets upon each other in zones intermediate the jets and thereby generate spaced counter-rotating tornadoes with laminar flow areas there between, with the tornadoes increasing in diameter and merging downstream of the areas of laminar flow, and delivering a stream of attenuable material into the influence of each jet in a region along the path thereof between said tornadoes.

12. A method as defined in Claim 11 in which the paths of the jets as deflected extend at an oblique angle to the vertical, and in which the streams of attenuable material are delivered downwardly by gravity into the influence of the jets.

13. A method for forming fibers from attenuable material comprising establishing a gaseous blast, establishing a series of spaced side by side gaseous jets each of smaller cross section than the blast and directed in paths having a predetermined relation to the path of the blast, deflecting the flow of the jets to alter the paths of the jets from said predetermined paths into paths intersecting the path of the blast and to cause lateral spreading of the jets, the jets being sufficiently close to each other to provide for impingement of adjacent deflected jets upon each other in zones intermediate said predetermined paths and thereby generate spaced counter-rotating tornadoes with laminar flow areas therebetween, with the tornadoes increasing in diameter and merging downstream of the areas of laminar flow, and the jets having sufficient kinetic energy per unit of volume to cause the deflected jets to penetrate the blast, and delivering a stream of attenuable material into the influence of each jet in a region along the path thereof between said tornadoes.

14. A method as defined in Claim 13 in which the jets are established in generally parallel relationship to the blast and from which the jets are deflected toward the path of blast.

15. A method as defined in Claim 13 in which the blast is established in a generally horizontal path, in which the jets are established in paths above the blast, in which the jets are deflected downwardly into the blast at an angle oblique to the vertical, and in which the streams of attenuable material are delivered vertically downwardly into the influence of the jets.

16. In the toration of fibers from attenuable ma-terial, the method of developing a toration blast, and a second-ary or carrier jet penetrating the blast and thereby developing a zone of interaction with the blast, which method comprises establishing a series of spaced side by side gaseous jets, subjecting the jets to deflection and thereby cause lateral spreading of the jets, the jets being sufficiently close to each other to provide for impingement of adjoining deflected jets upon each other in zones intermediate the jets and thereby generate spaced counter-rotating tornadoes at opposite sides of at least one of the said jets and with a laminar flow area between the spaced tornadoes, with the tornadoes increasing in diameter and merging downstream of the area of laminar flow, the deflected flow of said one jet including said tornadoes being directed in a path intersecting the path of the toration blast and having sufficient kinetic energy to penetrate the blast and thereby serve as a secondary or carrier jet for the purpose of fiber toration, and delivering a stream of the attenuable material into the influence of said one jet in a region between said tornadoes.

17. A method as defined in claim 16 in which the deflection of the jets is effected in a zone spaced appreciably from the boundary of the blast and in which the delivery of the stream of molten material to the jet is effected in a zone close to the zone of deflection and thereby provide for preliminary attenuation of the stream in the region of said tornadoes prior to toration of the fiber being formed in the zone of interaction between the secondary jet and the blast.

18. 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 laminar flow area in said gaseous flow with the laminar flow area exposed at one side of the gaseous flow and with the tornadoes increasing in diameter and ultimately merging downstream of the laminar area, and means for delivering a stream of attenuable mate-rial into the influence of the gaseous flow in a region along the path thereof in said exposed laminar flow area between said tornadoes.

19. Apparatus as defined in Claim 18 and further including means for generating a gaseous blast of larger cross section than said gaseous flow, the blast being di-rected in a path intercepting the path of said gaseous flow.

20. Apparatus for forming fibers from attenuable material comprising means for establishing a series of spaced gaseous jets directed in side by side generally parallel paths, means for deflecting the jets from said paths to alter the paths thereof and to cause lateral spreading of the jets, the jets being sufficiently close to provide for impingement of adjoining deflected jets upon each other in zones intermediate the jets and thereby generate spaced counter-rotating tornadoes with areas of laminar flow therebetween and with tornadoes increasing in diameter and merging downstream of the areas of laminar flow, and means for delivering a stream of attenu-able material into the influence of each jet in a region along the path thereof between said tornadoes.

21. Apparatus as defined in Claim 20 in which the means for deflecting the jets comprises a deflector plate pre-senting a deflecting surface at an oblique angle to the initial path of a plurality of the jets.

22. Apparatus as defined in Claim 21 in which an edge of the deflector plate lies along a line in the region of the axes of the jets.

23. Apparatus as defined in Claim 22 in which the free edge of the deflector is located from about 2 mm to about 5 mm from the jet orifices.

24. Apparatus as defined in Claim 21 in which the deflecting surface of the deflector plate is positioned at an angle of from about 35° to about 55° with respect to the axes of the jets.

25. Apparatus for forming fibers from attenuable material comprising means for establishing a series of spaced gaseous jets in side by side generally parallel paths, means in the paths of the jets for causing the jets to spread late-rally, the jets being sufficiently close to provide for impinge-ment of adjoining jets upon each other in zones intermediate the jets and thereby generate spaced counter-rotating tornadoes with areas of laminar flow therebetween and with tornadoes increasing in diameter and merging downstream of the areas of laminar flow, and means for delivering a stream of attenuable material into the influence of each jet in a region along the path thereof between said tornadoes.

26. Apparatus for forming fibers from attenuable material comprising means for establishing a gaseous blast, means for establishing a series of spaced side by side jets each of smaller cross section than the blast and directed in paths having a predetermined initial relation to the path of the blast, means for deflecting the flow of the jets to alter the paths of the jets from said predetermined paths into paths intersecting the path of the blast and to cause lateral spreading of the jets, the jets being sufficiently close to each other to provide for impingement of adjoining deflected jets upon each other in zones intermediate said predetermined paths and thereby generate spaced counter-rotating tornadoes with areas of laminar flow therebetween and with tornadoes increasing in diameter and merging downstream of the areas of laminar flow, and the jets having sufficient kinetic energy per unit of volume to cause the deflected jets to penetrate the blast, and means for delivering a stream of attenuable material into the influence of each jet in a region along the path thereof between said tornadoes.

27. Apparatus as defined in Claim 26 in which the means for deflecting the jets comprises a deflector plate pre-senting a deflecting surface at an oblique angle to the initial path of a plurality of the jets.

28. Apparatus as defined in Claim 27 in which the deflector plate has a free edge lying along a line in the region of the axes of the jets.

29. Apparatus as defined in Claim 28 in which the free edge of the deflector is located from about 2 mm to about 5 mm from the jet orifices.

30. Apparatus as defined in Claim 27 in which the deflecting surface of the deflector plate is positioned at an angle of from about 35° to about 55° with respect to the axes of the jets.