Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
74
METHOD FOR FIBERIZING
ATTENUABLE MATERIALS
BACKGROUND
The invention relates to the production of fine
fibers from attenuable materials, particularly attenuable
materials which soften upon entering a molten state as a
result of the application of heat and which harden or become
relatively solid upon cooling.
The method and equipment of the invention are
especially suited to the formation of fibers from glass ~ ;~
and the disclosure herein accordingly emphasizes production
of glass fibers from molten glass.
Many techniques are already known for production
of fibers from molten glass, some of the techniques most
widely used heretofore being identified and briefly described
just below.
1. Longitudinal Blowing: Other terms sometimes
used include "blown fiber", "steam blown wool",
"steam blown bonded mat", "low pressure air blowing",
or "lengthwise jets". ;
!
2. Strand: Other terms sometimes used are "con~
tinuous filament", or "textile fibers".
,, :
674
3. Aerocor: Another term sometimes used is
"flame attenuation".
4. Centrifuging: Other terms sometimes used
include "rotary process", "centrifugal process",
"tel process", or "supertel process".
There are numerous variants of each of the above
four processes, and some efforts in the art to combine certain
of the processes. Further, there are other techniques dis-
cussed in the prior art by which prior workers have attempted
to make glass fibers. However, the variants, attempted
combinations, and attempted other techniques, for the most
part have not ~et with sufficient success to achieve a separate
and recognizable status in the art.
The four techniques above referred to may briefly
be described as follows.
1. Longitudinal Blowing
Longitudinal blowing (examples of which are re-
ferred to as items 1, 2, 3 and 4 in the bibliography herebelow)
is a glass fiber manufacturing process according to which
melted glass flows from the forehearth of a furnace through `
orifices in one or two rows of tips protruding downwardly
from a bushing, the glass being thereby formed into multiple
glass streams which flow down into an attenuating zone where
`` 1~1~9~4
the streams pass between downwardly converging gaseous blasts.
The blast emitting means are located in close proximity
to the streams so that the converging blasts travel in a
downward direction substantially parallel to the direction
of travel of the glass streams. Generally the glass streams
bisect the angle between the converging blasts. The blasts
are typically high pressure steam.
There are two longitidunal blowing techniques.
In the first technique the attenuating blasts engage already
drawn fibers and the product resulting is typically a mat,
commonly known as "steam blown bonded mat", suitable for
reinforcement. In the second longitudinal blowing technique
the attenuating blasts strike directly on larger streams
of molten glass and the product resulting is typically an
insulation wool commonly known as "steam blown wool".
In a variation (see item 5) of the first longitudinal
blowing technique, the entire bushing structure and associated
furnace are enclosed within a pressure chamber so that,
as the streams of glass emerge from the bushing, the streams
are attenuated by pressurized air emerging from the pressure
chamber through a slot positioned directly beneath the glass
emitting tips of the bushing, this variation being commonly
referred to as "low pressure air blowing", and products
being commonly known as "low pressure air blown bonded mat
and staple yarn".
6~4
2. Strand
The strand glass fiber manufacturing process (see ~ -
items 6 and 7) begins in the manner described above in con~
nection with longitudinal blowing, that is, multiple glass
streams are formed by flow through orifices in tips protruding
downwardly from a bushing. However, the strand process
does not make use of any blast for attenuation purposes
but, on the contrary, uses mechanical pulling which is ac- ~
complished at high speed by means of a rotating drum onto ~-
which the fiber is wound or by means of rotating rollers
between which the fiber passes. The prior art in the field
of the strand process is extensive hut is of no real sig- -
nificance to the present invention. Strand techniques there-
fore need not be further considered herein.
3. Aerocor
In the aerocor process (see items 8 and 9) for
making glass fibers, the glass is fed into a high temperature
and high velocity blast while in the form of a solid rod,
rather than flowing in a liquid stream as in the longitudinal
blowing and strand processes discussed above. The rod, ~ ~
or sometimes a coarse filament, of glass is fed from a side, ,
usually substantially perpendicularly, into a hot gaseous
blast. The end of the rod is heated and softened by the
blast so that fiber can be attenuated therefrom by the force
of the blast, the fiber being carried away entrained in the
blast.
- . -~ . .. . ., . . . . . . -:
~7~
4. Centrifuging
In the centrifuging glass fiber manufacturing
process (see items 10 and 11) molten glass is fed into the
interior of a rapidly rotating centrifuge which has a plu~
rality of orifices in the periphery. The glass flows through
the orifices in the form of streams under the action of
centrifugal force and the glass streams then come under
the influence of a concentric and generally downwardly di-
rected hot blast of flames or hot gas, and may also, at
a location concentric with the first blast and farther outboard
from the centrifuge, come under the action of another high
speed downward blast, which latter is generally high pressure
air or steam. The glass streams are thereby attenua~ed - -`
into fine fibers which are cooled and discharged downwardly
in the form of glass wool. ~
- ~,
In addition to the four categories of fiber forming
techniques which have been very generally referred to and
distinguished above, various refinements and variations
of those techniques have also been known and repeated efforts
have been made to optimize the manufacture of glass fibers -
by one or more of the processes which start with molten
streams of glass. Various of these prior art techniques
have been concerned with trying to optimize the attenuation
process by extending or lengthening the attenuation zone,
either by providing special means to accomplish the addition
of heat to the streams of glass and to the embryonic fibers
~674
(see item 12), or through the use of confining jets (see
items 13 and 14), or both (see item 15).
The approach taken in the just mentioned prior
art technique suggests that the realization of optimum fiberi-
zation lies in extending the length of a single attenuatingzone.
In contrast, in the practice of the present in-
vention, attenuation is accomplished by subjecting a glass
stream to two sequential stages of attenuation, performed
under different conditions, as will further appear.
Various other approaches have been suggested for
introducing glass in the molten state into an attenuating `
blast (see items 16, 17, 18 and 19). In such attempts to
introduce a stream of molten glass into an attenuating blast -~
it has been noted that there often is a tendency for the
glass stream to veer to a path of travel on the periphery
of the blast, that is, to "ride" the blast, rather than
penetrating into the core region of the blast where attenuating ~ ~ .
conditions are more effective. Suggestions have been made
to deal with this "riding" problem, including the use of
physical baffles as in Fletcher (item 16), and the transfer
of substantial kinetic energy to the glass stream as, for
example, by the modifications of the centrifuging process
taught in Levecque (item 11), Paymal (item 18), and Battigelli
(item 19).
, . : - - - . ~ . - , , . . . :
11~96t74
An alternate approach to the problem, more closely
akin to the aerocor process, has been the introduction of
the glass in the form of a solid (item 9) or pre-softened : :
(item 20) glass rod or in the form of powdered glass (item
14)-
,",: ~
BIBLIOGRAPHY OF PRIOR PATENTS
(1) Slayter et al 2,133,236
(2) Slayter et al 2,206,058
(3) Slayter et al 2,257,767
(4) Slayter et al 2,810,157
(5) Dockerty 2,286,903
(6) Slayter et al 2,729,027
(7) Day et al 3,269,820 -- ~
(8) Stalego 2,489,243 ~ :
(9) Stalego 2,754,541 :
(10) Levecque et al 2,991,507
(11) Levecque et al 3,215,514
(12) Stalego 2,687,551
(13) Stalego 2,699,631
(14) Karlovitz et al 2,925,620
(15) Karlovitz 2,982,991
(16) Fletcher 2,717,416
(17) Eberle 3,357,808 ~:
(18) Paymal 3,634,055
(19) Battigelli 3,649,232
(20) Stalego 2,607,075
i7~
General Statement of the Invention and Objects
In contrast with all of the foregoing prior art
techniques, it is a major objective of the present invention
to provide certain improvements in the production of fibers
from streams of molten glass or similar attenuable materials.
The technique of the present invention in part utilizes
the fiber "toration" techniques or principles disclosed
in our prior Canadian applications above identified Serial
No. 245,501, and Serial No, 196,097, filed February 11,
1979 and March 27, 1974, respectively. Such toration techniques
are also disclosed in U.S.A. patent No. 3,885,940, issued -
May 27, 1975. Thus, the technique of the present invention ~ ;
makes use of the attenuating capability of a zone of inter-
action developed by the direction of a secondary jet or ~`
relatively small cross section transversely into a principle
blast or jet of relatively large cross section. However,
according to the present invention, instead of directly
admitting or delivering a stream of molten glass to the
zone of interaction, the glass stream is delivered from
an appropriate orifice spaced an appreciable distance above
the zone of interaction.
The present application is a division of our prior
application Serial No. 265,560, filed November 12, 1976.
674
In accordance with one aspect of the present in-
vention a process is provided for forming fibers from attenuable
thermoplastic mineral material, characterized by generating
a gaseous jet, generating a gaseous blast in a path inter-
cepting the jet, the cross-sectional dimension of the jet
being smaller than that of the blast in a direction transverse
to the blast, and the jet being of temperature and velocity ~:
below that of the blast, but having density and thus kinetic
energy per unit of volume higher than that of the blast there- ~ `
10 by providing for penetration of the jet into the blast to : ::
thereby produce a zone of interaction of the jet and blast, -:
and delivering a stream of attenuable material from a region -
spaced from the blaæt into said zone of interaction.
In accordance with another aspect, the gaseous
jet is generated in a region spaced from the boundary of
the blast and directed toward the blast, the jet having
a jet core inducing ambient gases before the jet reaches ~ -
the blast, the combined flow of the jet core and the induced
gases having a temperature and thus a density providing ~ :
kinetic energy per unit of volume sufficiently high to pene-
trate the blast and thereby provide said zone of interaction ;~ ~ -
with the blast, and the stream of attenuable material being
delivered into the influence of the gases induced by the -
jet so that the stream of attenuable material is carried
by the jet into said zone of interaction.
_9_ :
?6~4
Moreover, in a typical technique according to
the present invention, the blast is discharged in a generally
horizontal direction, the glass admission orifices are arrang-
ed in spaced relation above the blast, and at an intermediate
elevation, secondary jets are discharged downwardly toward
the blast from jet orifices positioned adjacent to the de-
scending glass streams, and preferably inclined somewhat -
with respect to the vertical, so that the glass streams
enter the influence of the jets at a point above the upper
boundary of the blast, but well below the glass orifices.
Preferably also each secondary jet orifice and the associated
glass stream are spaced from each other in a direction upstream
and downstream of the direction of flow of the blast, with
the jet orifice located, with respect to the direction of
flow of the blast, on the upstream side of the glass stream.
The system of the invention, as just briefly des-
cribed, functions in the following manner:
Each secondary jet, being spaced appreciably above
the upper boundary of the blast, causes induction of the
ambient air so that the jet develops a sheath or envelope -r
of induced air which progressively increases in diameter
as the upper boundary of the blast is approached. The jet
thus is comprised of two portions, i.e. the core itself
which is initially delivered from the jet orifice and the
main body of the jet which is frequently referred to as ~-
--10--
67~
the mixing zone, i.e. the zone represented by the mixture
of the gas of the core with induced air.
In a typical embodiment, the jet core extends
for a distance beyond the jet orifice equal to from 3 to
10 times the diameter of the jet orifice, depending primarily ;;
upon the velocity of the jet through the orifice. Since
in installations of the kind here involved, the jet orifices -
are of only very small diameter, the extent to which the
jet core is projected beyond the orifice is relatively short.
The jet core is conical and the mixing zone surrounds the
jet core from the region of delivery from the jet orifice
and is of progressively increasing diameter downstream of ~
the jet, including a length of travel extended well beyond
the tip of the jet core cone. In such a typical installation,
the spacing between the jet orifice and the boundary of
the blast is such that the point of intersection of the
blast lies beyond the tip of the core, although with certain
proportions the jet core may come close to or somewhat pene-
trate the blast. In any event, it is contemplated that
at the point of intersection of the jet and blast, the body
of the jet or jet stream retains sufficient kinetic energy
or velocity to penetrate the blast and thereby develop a
zone of interaction between the jet and the blast. This
zone of interaction has the same general characteristics
as the zone of interaction referred to and fully described
in the prior Canadian applications and in the U.S.A. patent,
above identified.
--11--
967~
With the foregoing in mind, attention is now directed
to the glass stream and its behavoir in relation to the
jet and blast. As already noted, the glass stream is delivered
from an orifice spaced above the blast and also spaced ap-
preciably above the point of delivery or discharge of thesecondary jet. Preferably the glass discharge orifice is
so located as to deliver a stream of glass which by free-
fall under the action of gravity will follow a path which
would intersect the axis of the jet at a point appreciably -
above the upper boundary of the blast and thus also above
the zone of interaction. As the glass stream approaches
the jet, it is influenced by the currents of induced air
and is thereby caused to deflect toward the jet above the
point where the glass stream would otherwise have intersected
the axis of the jet. The induction effect causes the stream
of glass to approach the jet and, depending upon the position
of the glass orifice, the induction effect will either cause
the glass stream to enter the envelope of induced air surrounding
the core, or will cause the glass stream to enter the main
body of the jet at a point downstream of the jet core.
In either case, the glass stream will follow a path leading ;~ ;
into the mixing zone and the glass stream will travel within ;
the body of the jet downwardly to the zone of interaction
with the blast.
~. ,
Thus, the glass stream is carried by the induced
air currents into the mixing zone of the jet, but does not
penetrate the jet core. The glass stream may be carried
'
-12-
.,
- -.
67~
by the induced air to the surface of the jet core, but will ~ *
not penetrate the core, which is desirable in order to avoid ~
fragmentation of the glass stream. Since the glass stream ~r
is at this time in the influence of the mixing zone of the
S jet, the stream of glass will be subjected to a preliminary ~ -
attenuating action and its velocity will increase as the
upper boundary of the blast is approached.
In addition to this attenuating action, which
is aerodynamic in character, the attenuating stream is sub-
jected to certain other dynamic forces tending to augment
the attenuation. This latter attenuation action is caused
by the tendency for the attenuated stream to move toward
the center of the jet and then be reflected toward the boundary
of the jet into the influence of the air being induced.
The attenuating stream is then again caused to enter into
the interior of the jet. This repeated impulsion supplements
the aerodynamic attenuating action.
In the region of interaction with the blast, the
partially attenuated stream of glass will be caused to enter
the zone of interaction, in part because of the acceleration -
of the glass resulting from the action of gravity and from
the preliminary attenuation described just above, and in
part under the influence of the currents established in
the zone of interaction itself, in the manner fully explained
in our prior applications above identified.
-13-
1~96~4
Thus it will be seen, that according to the invention,
the glass stream is subjected to two successive stages of
attenuation. It is also to be observed that since the glass
stream is caused to come under the influence of the jet --
by virtue of the induced currents surrounding the jet, the
preliminary attenuation is accomplished without fragmenting
the glass stream. Moreover the succeeding or second stage
of attenuation which is effected in the zone of interaction j-
between the jet and the blast is also accomplished without ;~ ~
fragmenting the fiber being formed. By this two stage at- ~ -
tenuating technique it is thus possible to produce long
fibers.
The technique of the present invention has important
advantages as compared with various prior techniques. Thus,
it provides a technique for the production of long fibers
while at the same time making possible greater separation
between certain components of the equipment, notably the
blast generator or burner, with its nozzle or lips, the
jet nozzle and the gas or air supply means associated therewith ;
and the glass supply means including the bushing or similar ;
equipment having glass orifices. This separation of com- -~
. .
ponents is not only of advantage from the standpoint of
facilitating orifices and higher temperatures may be used
in the supply of the molten material, it becomes feasible
to establish uniformity of feed and attenuation even with
certain classes of attenuable materials which could not
otherwise be employed in a technique based upon production
of fibers by attenuation of a stream of molten material.
'~ ,
~;74
It is also noted that various of the four principle
prior art techniques referred to above are subject to a
number of limitations and disadvantages. For example, various
of the prior techniques are limited from the standpoint
of production capacity or "orifice pull rate", i.e. the
amount of production accomplished within a given time by
a single fiber producing center. In other cases, the fiber
product contains undesirable quantities of unfiberized material.
Strand type of operations, while effective for producing
strand material, are not best suited for production of in-
sulation type of fiber blanket and other similar types of ;
products. Centrifuging, while effective for producing
fiber insulation blanket has the disadvantage that the centri-
fuge must rotate at high speed, thus necessitating special
working parts and maintenance, and further because the centrifuge
is required to be formed of special alloys capable of with- `
standing the high temperatures.
Another general objective of the present invention
is to provide a technique which overcomes various of the
foregoing disadvantages or limitations of the prior art
techniques referred to.
Moreover, the technique of the present invention
provides for high production rates and utilizes only static
equipment.
-15-
Detailed Description of the Invention
The accompanying drawings illustrate, on an enlarged
scale, a preferred embodiment of the present invention, ~-
and in these drawings
Figure 1 is a fragmentary isometric view showing
equipment including means for developing a blast, means
for developing a series of secondary jets above the blast
and directed downwardly toward the blast, together with
means for establishing glass streams delivered by gravity ~
from a region above the jets downwardly into the zone of - -
influence of the jets and ultimately into the influence
of the zone of interaction with the blast; ;
Figure 2 is a vertical sectional view through -~
equipment for establishing a single fiberizing station as
arranged according to the present invention; and
Figure 3 is a view similar to Figure 2 but more :
diagrammatic and further illustrating certain dimensional
relationships to be taken into account in establishing oper-
ating conditions in accordance with the preferred practice ; :
of the present invention. :
In the drawings, the glass supply means includes :
a crucible or bushing 1 which may be supplied with molten
glass in any of a variety of ways, for instance by means
of the forehearth indicated at 2 in Figure 3. Glass supply `
orifices 3 deliver streams of molten glass downwardly under -~
the action of gravity as indicated at S.
-16-
A gaseous blast is discharged in a generally hori-
zontal direction from the discharge nozzle 4, the blast
being indicated by the arrow 5. The blast may originate
in a generator, usually comprising a burner, so that the
blast consists of the products of combustion, with or without
supplemental air.
As will be seen from the drawings, the blast is
directed generally horizontally below the orifices 3 from -
which the glass streams S are discharged.
'
At an elevation intermediate the crucible and
the blast discharge device 4, jet tubes 6 are provided,
each having a discharge orifice 7, the jet tubes receiving ~-~
gas from the manifold 8 which in turn may be supplied through
the connection fragmentarily indicated at 9.
. . .
The gases for delivery to and through the jet
tubes 6 may originate in a gas generator taking the form
of a burner and the products of combustion may serve for
the jet, either with or without supplemental air. Preferably
the combustion gases are diluted with air so as to avoid
excessively high temperature of the gas delivered through
the jet tubes.
Each jet tube 6 and its orifice 7 is arranged
to discharge a gaseous jet downwardly at a point closely
adjacent to the feed path of one of the glass streams S
and preferably at the side of the stream S which, with
-17-
~ 9~i7~
respect to the direction of flow of the blast 5, is upstream
of the glass stream. Moreover, each jet tube 6 and its
orifice 7 is arranged to discharge the jet in a path direct-
ed downwardly toward the blast and which is inclined to
the vertical and so that the projection of the paths of
the glass stream and the jet intersect at a point spaced
above the upper boundary of the blast 5.
It is contemplated that the vertical dimension
of the blast and also the width thereof be considerably
greater than the cross sectional dimensions of each secondary
jet, so that adequate volume of the blast will be available
for each jet to develop a zone of interaction with the blast. ;
For this purpose also, it is further contemplated that the
kinetic energy of the jet in relation to that of the blast,
in the operational zone of the jet and blast, should be
sufficiently high so that the jet will penetrate the blast.
As pointed out in our applications above referred to, this
requires that the kinetic energy be substantially hiqher
than that of the blast, per unit of volume. Still further,
the jet preferably has a velocity considerably in excess
of the velocity of the glass stream as fed under the action
of qravity downwardly toward the point of contact with the
jet and sometimes also in excess of the velocity of the
blast.
25The operation of each fiberizing center is as
follows:
-18-
11~9{~74
From the drawings and especially from Figure 2,
it will be seen that the core C of the jet causes the induction
of currents of air indicated by the lines A, the amount
of air so induced progressively increasing along the path
of the jet. When the body of the jet, i.e. the gas of the
core intermixed with the induced air, reaches the boundary
of the blast, a zone of interaction is established in the
region indicated by cross-lining marked I in Figure 2.
As the stream S of molten glass descends and ap-
proaches the jet delivered from the orifice 7, the currents
of air induced by the action of the jet cause the stream
of glass to deflect toward the jet core as indicated at
10. Although the glass orifice 3 may be of substantially ~ ~;
larger diameter or cross section than the jet orifice 7, ~ ;
the gravity feed of the glass stream S results in substantial -
reduction in diameter of the glass stream, so that when
the stream meets the jet, the diameter of the stream is
much smaller than the diameter of the glass orifice. With
the higher velocity of the jet, as compared with that of
glass stream, even when the glass stream meets the jet in
the upstream region adjacent the jet core, the glass stream -
will not penetrate the jet core. However, because of the
induced air currents surrounding the jet, the glass stream
is caused to "ride" on the surface of the jet core within
the surrounding sheath of induced air or to enter the body
of the jet downstream of the jet core. -
--19--
- - , ` . . . . . . . . .
" : ,
?674
The action of the induced air in bringing the
glass stream to the jet stabilizes the feed of the glass
stream and will also assist in compensating for minor mis-
alignment of the glass orifice with respect to the jet orifice.
5 Because of the reliance upon induction effects of an isolated ~ '-
jet, the glass stream is brought into the mixing zone of
the gas originating in the jet core and the induced air
without subdivision or breakage of the stream or the fiber
being formed. This action is enhanced by virtue of the `~
fact that in the arrangement as above described and illustrat-
ed, the glass stream is not subjected to any sharp angled
change in its path of movement before it has been subjected ~-
to some appreciable attenuation, thereby reducing its diameter
and inertia.
In consequence of the glass stream being carried -
in the mixing zone of the jet, the glass stream is partially
attenuated, this action representing the first stage of
the two-stage attenuation above referred to. In turn, in
consequence of this partial attenuation, the length of the
embryonic fiber is increased, and this increase in length
is accommodated by an undulating or whipping action, thereby
forming loops, as indicated at 12. It is to be noted, how-
ever, that the glass stream remains intact, the loops of
the embryonic fiber being carried downardly in the mixing
zone.
-20-
'. . : .,. .. .~ r
~6~4
At the point where the blast 5 intercepts the
jet, the jet penetrates the blast. This penetration of
the blast by the jet establishes currents in the zone of
interaction of the jet with the blast, which currents carry
the partially attenuated glass stream into the interior
of the blast and in consequence a second stage of attenuation
occurs. This results in further increase in the length
of the fiber being formed. The increase in fiber length -
is accommodated by additional undulating or whipping action,
forming further enlarged loops as indicated at 13 within
the blast. Notwithstanding this action, a typical fiber
will remain intact and will be carried away by the blast
flow in the form of a fiber of considerable length. Thus
a single stream of molten glass is converted into a single
glass fiber by a two-stage attenuation operation. It will
be understood that in effecting this two-stage attenuation,
the temperature of the glass and the temperature of the
jet, as well as the temperature of the blast, are established
at values which will retain the glass in attenuable condition
throughout the first stage of attenuation and throughout
the second stage until the attenuation has been completed
in the zone of interaction between the jet and the blast.
In connection with the arrangement of the invention,
it is to be understood that fiberizing centers may be arranged
in multiple, as illustrated in Figure 1. This is accomplished
by employing a blast 5 which is broad or of large dimension
in the direction perpendicular to the plane of Figure 2,
-21-
; . . : , . . .
9l;7~
and by employing a similarly extended crucible 1 having
a multiplicity of glass orifices, and further by employing
.. . .
a multiplicity of jet tubes 6 each having an orifice adjacent
to one of the streams S of glass being delivered from the
several glass orifices, all as shown in Figure 1. Such ~ ;~
a multiplicity of jet tubes may be supplied with the jet : -
gas from a common manifold 8.
In connection with various dimensional relation-
ships involved in the equipment of the present invention, ~
particular attention is directed to Figure 3 on which cer- -.
tain symbols have been applied to identify some of the di-
mensions. These are identified in the following table which
also gives an average or typical value in millimeters, as -~
well as a usable range for each such value. ;~
AVERAGE VARIATION - ~-
VALUE LIMITS - -
FEATURE DIMENSION SYMBOL (mm) (mm)
Bushinq Diameter of glass dT 4 1 - 10
orifice ~
Distance between 2 holes 10 5 :-
Jet Inner diameter of jet tube dt l 0.3 - 3
Outer diameter of jet tube 1.5 0.7 - 5 .: ~
Separation between 2 tubes 10 5 ~ :
Blast Vertical distance between 1 25 10 - 50
the lips or thickness of B
the discharge section
Width of the discharge 3300 20 - 500
section
.~ . - ,. :........ , , :
... - . ~ , . .. .
11~;~4
In addition to the foregoing dimensions, certain
spacing relationships and also angular relationships should
be observed, as indicated in the following table which gives
an average or typical value in millimeters or degrees, as
well as a usable range for each such value.
AVERAGE VARIATION
VALUE LIMITS
(mm or (mm or
FEATURES SYMBOL degree) degree)
Vertical distance of jet discharge Z B 45 30 - ~0
orifice to the upper boundary of J
flow of the blast
Vertical distance from the dis-ZJF 85 0 - 150 ~ -
charge opening of the glass stream
to the jet discharge orifice -~:
Horizontal distance from the axis x 5 1 - 15
of the glass stream to the jetJF
discharge orifice
Horizontal distance from the axis X 5 0 - 30
of the glass stream to the lip of BF
the blast nozzle
Angle of jet tube to the axis jf 10 3 - 45
of glass stream
Angle of jet tube to the direction JB 80 87 - 45
of flow of the blast
With further reference to parameters of operation ~
when employing the technique of the present invention, it ~ --
is first pointed out that it is of course important that
the glass be discharged from the glass orifice in a contin-
ous stable stream. For this purpose, the rate of glass
flow, the temperature of the bushing and the diameter of
the glass discharge orifice should preferably be above cer-
tain predetermined limits. Thus, the pull rate of glass
-23-
1~9674
should be greater than 60 kg/hole for each 24 hour period;
the bushing temperature should be greater than 1250C, and
the diameter of the glass discharge orifice should be greater
than 2.5 millimeters. With at least certain types of glass
formulations, observing these limits may assist in avoiding
pulsations which have a tendency to accentuate until distinct
droplets are formed. This phenomenon is incompatible with
proper fiberization. In a typical or average working condi-
tion, the following values are appropriate; 100 kg/hole -
per day, bushing temperature 1400C, glass orifice diameters
3 millimeters.
Additional operating ranges are as follows:
Velocity - jet 200 m/sec - 900 m/sec
blast 200 m/sec - 800 m/sec
15 Pressure - jet .5 to 50 bars
blast .05 to .5 bars
Temperature - jet 20 to 1800C
blast 1300 to 1800C
Kinetic EnerqY Ratio - jet to blast 10/1 - 1000/1
A typical operation according to the present in-
vention may be carried out as given in the Example below. -
-24-
9674
Example
~ .,
Glass formulation:
SiO2 46.92
Fe203 1.62
A1203 9.20 ~ -
MnO 0.16
CaO 30.75
MgO 3.95
Na20 3.90
K20 3.50
All parts by weight.
PhYsical ProPerties ~:
,:
Viscosity 30 poises at 1310C ~ ;
100 poises at 1216C
300 poises at 1155C
Glass - orifice 3 mm
flow 100 kg/day per orifice
Blast - temperature 1550C
pressure .25 bar
velocity 530 m/s
Jet - temperature 20C
pressure 6 bar
1~9674
,,
velocity 330 m/s
orifice diameter 1 mm
Ratio of Kinetic energies Jet = 24 :
Blast
5 Fiber diameter - 6 microns ~ .
-2~
