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Патент USA US2116693

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May 1U, 1938.
"
F, L, BlSHOP '
2,115,693
MANUFACTURE OF SHEET GLASS
Filed Sept. 8‘, 1934
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INVENTOR
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Patented May
1938
' 2,116,693 I: ‘x
h
7 uNiTEosTATss' PATENXT" OFFICE
2,116,693 '
MANUFACTURE OF SHEET GL‘ASS
Frederic L. Bishop, Foxv ChapeLPa.! 881M ‘0
American Window Glass Oompany, Pittsbursh,
Pa, a corporation of Pennsylvania
Application September 8, 1934, Serial No. 143.224.
1“: Claims.
‘(01. 49-3)
The present invention relates broadly to the
manufacture of’ sheet glass, and more particu
.
'
.
glass may be eliminated and the'strain remaining
in the sheet uniformly distributed. It is not
larly to the annealing thereof and the removal f neca‘s‘ary that the gaseous medium circulate
from the drawn glass sheet of. at least a portion exactly horizontally across the sheet. It is suf?
cient if it is circulated ina direction across the 5
of the characteristic wave of drawn- glass.
By my invention I provide antimproved method sheet having a horizontal component and this is
of_ manufacturing sheet glass whereby the sheet the sense in which the word transversely is used
may be properly annealed during the continuous herein. The annealing range is approximately
850° to 1100? F. Where my invention is prac-~
drawing thereof in 'a vertically extending direc
tion from a tank containing a bath of molten ticed, the strain remaining in the sheet is of no 10‘
' glass and whereby a substantial portion of the . moment asit does not detrimentally affect the
'
characteristic wave of drawn glass may be character of the ‘product.
The circulation of the gaseous medium may
eliminated. The product resulting from my im
proved method of manufacture is superior to the be effected in various different ways, some of g
which are speci?cally described andclaimed in‘ 15
products obtained by the-presently known meth
ods of drawing sheet glass, for example, the the copending application of William Ii. Monro.
Serial No. 743,207,'?led of even date herewith,
Fourcault process, by reason of the proper an
now Patent No. 2,002,544. For example, highly
nealing thereof and the removal of the char
desirable results may be obtained where the
- acteristic wave therefrom.
gaseous medium in the drawing pit or in the base 2“
It
is
well
known
that
in
the
Fourcault
process
20
a continuous sheet is drawn from a bath of molten of the leer adjacent the glass sheet is circulated
glass and ls'passed vertically past coolers which 5 transversely of the rising sheet. ‘I have also
found that the advantages of my invention may
be obtained where blowers ‘are utilized for blow
ing additional air into the drawing pit or the base 25
which the continuous sheet is cut o? in lengths. ~ of the leer and transversely of the sheet. An
Heretoiore it has been deemed impossible to ordinary blower for blowing atmospheric air into
- properly anneal the rising glass sheet. I have ' the pit or leer may be used, as may a Venturi type
found that the difficulty arises from two factors, blower for blowing fresh air and a portion of the
first, insuflicient annealing, and second, lack' of gaseous medium already in the pit or leer trans- 30
set the sheet. The sheet then continues up
.wardly through the drawing pit and into and
25 through a vertically extending leer, at the. top of
80
uniformity in annealing. This latter factor,
versely of the sheet. It is essential, however.
which seems not to have been appreciated in the
_ past, is highly important. It is unnecessary for
rising glass sheet be circulated transversely of
most purposes to totally eliminate the strain from
.35 the glass, ‘but it is desirable to eliminate a major
portion thereof and substantially uniformlyfto
distribute the remaining strain through the
sheet. A certain amount of residual strain is
desirable in certain cases because such glass is.
40 less likely to break under certain conditions than
a perfectly annealed sheet. However, if the
residual strain‘is not distributed by uniform an- '
healing there is increased danger of breakage and
also the likelihood that in cutting such a sheet
45 the cut will ‘run of! line. Glass which is non
uniformly strained is particularly undesirable in‘
sheets which are to be ground and polished, not
only because of the danger of breakage, but also
because the grinding and polishing is not likely
‘
50 to be uniformI have found that by circulating a gaseous
medium in contact with and transversely of ‘the
moving glass sheet, while the temperature of the
sheet is above the lower limit of the annealing
55 range, the introduction of undue strain. in the
that the gaseous medium in contact with the _
the sheet. Advantageous annealing may be
_
effected where this circulation is accomplished 35
when the temperature of the sheet is above the.
annealing range, but I have found that the best
results from the annealing standpoint can be ‘
obtained where the transverse circulation is
effected where the glass is either within or adia- >40
cent the annealing range.
-
'
,
.
I, have found that desirable results can be ob
tained where‘one or more blowers or fans for >
circulating the gaseous medium is utilized. _
results have been obtained with only a single 45
blower or fan, but my observation indicates that
it is preferable to provide at least two sources of .
supply, one located adjacent one edge of the sheet
and adapted to cause circulation transversely
across one face of the rising sheet, and the other 1
means to be located adjacent the opposite edge of
the rising glass sheet and arranged to cause cir
culation across the other face of the sheet. In
this way a sheath of circulating gaseous medium
about the glass sheet may be obtained.
J
‘
2
2,116,698
It is well known that in the Fourcault process
temperature of about 200° F.
a characteristic wave extending longitudinally
In the preferred form of the invention a blower
I l ‘supplies atmospheric air under pressure to the
drawing pit. The blower is located to one side of
the glass sheet so that it will cause transverse
' of the , drawn sheet.
I have found that by cir
culating the gaseous medium ‘contacting the ris
ing glass sheet transversely of the rising sheet
a
and at a point or points where the temperature
circulation of the gaseous medium adjacent the
of the glass sheet is within or above the anneal
rising glass sheet. A similar-blower I2 .is pro
ing range, this characteristic wave may be either
10 totally eliminated or appreciably reduced. This
is particularly advantageous in sheet glass for the
product closely approximates the smooth surface
characteristics of plate glass.
' I have found that for purposes ot removing the
15 characteristic wave in sheet glass best results
can be obtained where the transverse circulation
is effected at a point where the temperature of
the glass sheet is above the annealing range.
This transverse circulation may be effected at the
meniscus, in the range immediately above the
meniscus, which may be termed the drawing
range, in the setting range, or in the range be
'
it ‘emerges from the top of the leer 8 it has a
of drawing glass sheets the ?nished product has
tween the annealing range and the setting range. _
>
vided at the diagonally opposite corner of the pit.
The blowers, when positioned in this manner, 10
effect an excellent transverse circulation or the
gaseous medium around the sheet. Stray con
vection currents, causing local chilling, are there
by eliminated and a gaseous sheath, substantially
uniform as to temperature or at least free of ~15
marked and sudden differences in temperature, is
formed. As shown in Figure 1, the blowers or
other gas circulating means in the pit are placed
outside the coolers. This is found to give de
sirable results without any danger of crizzling
the sheet by reason of cold air striking it.
The blower II is provided with two inlets l3 '
and H for injecting air into the pit. The supply
I prefer to effect the transverse circulation of the of air through the inlet l3 may be controlled by a
gaseous medium a short distance above the valve I5 and the supply through, the inlet Il
meniscus and before the sheet has become set, may be controlled by a similar valve IS. The
although it will be understood that advantageous _inlets l3_.and “are, as shown in the drawings,
results from the standpoint of wave removal may -* spaced vertically ‘so that air may be injected at ~
be obtained where this transverse circulation is vertically spaced points along the path of travel
of the sheet.
,
a effected at any of the points above mentioned.
The blower i2 is also provided with two ver
I have found that the transverse circulation of
the gaseous medium adjacent the rising glass tically spaced inlet openings l1 and I8 for in
sheet while the sheet is within the setting range, ~jecting air into the pit. The supply of 2 air
the range just abovethe annealing range, or at through these openings is controlled by valves
35 or adjacent the meniscus not only reduces or
I 9 and 20. For circulating air transversely of 35
eliminates waves but materially aids in e?ecting the rising glass sheet in the base of the leer,
pipes 25 and 26 are provided. The supply of air
proper annealing ofv the glass sheet.
In the accompanying drawings, I have shown passing through the pipes 25 and 26 may be ap
for purposes of illustration only apparatus which propriately regulated by valves 28 and 28. Ap
.may be used in carrying out my invention. It propriate connections 29 and 30 are provided for
will be understood that my invention is not connecting the pipes 25 and 26 to either the
limited to the particular apparatus shown in the blowers Ii and I! or other similar blowers.
The gaseous medium contacting the sheet may
drawingsand that my invention may be readily
practiced by various modi?cations thereoii and by be circulated either in the pit or in the base of
the leer. It is only essential that this movement
various other types of apparatus adapted to pro
of the contacting gaseous medium is placed
vide for transverse circulation of the gaseous me
dium contacting the rising glass sheet at a point about the sheet at a time when the temperature
of the rising glass sheet is adjacent to, within
or points where the temperature thereof is ad
jacent or above the lower limit of the annealing or above the annealing range.
A Venturi type of blower may be used inplace
range, that is, adjacent or within the annealing
of the type of blower shown in the drawings.
range in the range immediately above the an
nealing range in the setting zone or at the In the event this type of blower is used, some
of the gas already within the pit or base of the
leer will be entrained along with the additional
In the drawings:
Figure 1 is a vertical sectional view through gaseous medium injected into the pit or base
of the leer by the blower.
"
a glass drawing tank and a portion of the draw
It is unnecessary to inject any additional gas
i118 apparatus;
Figure 2 is a section taken along the line II—lI ~ eous medium into the pit or the base of the leer,
for satisfactory results may be obtained by locat
of Figure 1: and
?gure 3 is a section taken along the line ing fans or blowers within the pit or base of
meniscus.
-
'
III-III of Figure 2.
.
a
the leer in such manner as to cause the trans-.
verse circulation of the gaseous medium therein
The sheet S is drawn from a bath B in the tank and adjacent the sheet.
' _
4 in the usual manner. As shown in the draw- '
Polariscope tests on the product resulting from
,ingsdihe sheet is drawn through a debiteuse 5 the practice of my process show- that the product
, located in the pit 6 of the tank.- It then passes is properly annealedv and a substantial portion
upwardly through the mouth ‘I of the tank and ’of the strain removed, and the balance remainé
into the leer 8 where it is carried upwardly by ~ing in-the ‘sheet is su?lciently imiformly distrib
means oil a plurality of sets of rolls 9._ Coolers
70 III are provided adjacent the meniscus for cool
uted therethrough as to not detrlmentally a?ect
the character of the product. The product ob 70
ing and setting the sheet as it is drawn upw: dly tained in this manner can be readily out without
through the slot in- the debiteuse.
\
breakage occasioned by any strain which may
As the sheet moves'upwardly it cools to and ba'therein, and may be readily ground and pol
through the ‘annealing range and then pro
ished without breakage resul’
15 gressively drops in temperature until at the timeg Furthermore,- the product ob
g from strain.
fed from the
amass“
practice oi my process is
iree oithe
characteristic wave oi ordinary
glass
sheets. The ‘advantages of eliminating these
characteristic waves will be readily apparent to
‘thoseskilledintheartandneednotbesetiorth
herein.
.
While I have shown and, described] the pre
ierred method-oi practicing my invention and an
.
a
bani oi molten glass, the steps consisting in mm;
ing the sheet, and circulating a gaseousmedium
incontactvwith and transversely of the sheet sub- '
stantially at the meniscus and also while the tem
perature oi the sheet is substantially at the a_n- '
nealing range.
9. In'the method of annealing a glass sheet‘
during the continuous drawing thergii from ‘a '
apparatus ior carrying out the same, it will be tank containing a-bath of molten glass and in a
'10 understood that I do not intend to be'limited vvertically extending direction through the draw
ing pit and a leer, the steps comprising iorming
thereby but that my invention may be other
wise practiced within the scope oi the iollowing the sheet, and circulating a gaseous medium in
the base of the leer transversely oi the rising,
claims.
'
sheet ircm'one edge oi the sheet toward the other
I claim: >
_
i'
.
1. In the method of annealing a glass sheet edge thereoi’.
' 10. In the method-oi annealing a glass sheet :
during the continuous drawing ther'eoi in‘ aver
tically ‘extending direction irom a bath oi molten ' during the continuous drawing thereoi from a
glass, the steps comprising forming the glass tank of molten glass and in axvertically extend
sheet, and. while the temperature oi the sheet is ing direction through the drawing pit and a leer,
substantially-at the annealing range, ‘circulating ‘ the steps comprising forming the sheet, circus
a gaseous medium in. contact with and trans
, versely of the moving sheet irom one edge oi
lating a gaseous medium in the pit transversely
of the sheet and circulating a gaseous medium in '
the base oi the leer transversely oi the rising
2. In the method oi annealing a glass sheet , sheet from one edge oi the sheet toward the other
I sheet toward the other edge thereoi.
during the continuous drawing thereoi in a0:81‘!
edge thereof.I
,
_ _
glass, the steps comprising iorming, the glassv
11. In the'method oi annealing a glass sheet
during the continuous drawing thereof from a
bath of \molten glass, the steps consisting in
sheath oi said circulating gaseous medium
iorming the sheet and circulating a gaseous me
- 13. Apparatus for drawing sheet glass com
; tically extending direction irom a bath oi m ten
sheet, and, while'the temperature oi . the sheet tank containing a bath oi molten glass and in a
is abovethe lower limit oi the annealing range, ~vertically extending direction through the draw
circulating agaseous medium in contact with . ing pit anda leer’, the steps comprising iorming 80
and transversely of the moving sheet irc'm one the sheet, and, while the temperature of the
edge oi the sheet toward the other edge thereci. sheet is substantially at, the annealingrange. cir
8. In the method ci iorming a glass sheet by culating a gaseous medium transversely oi the
continuous drawing irom a tank containing a -\sheet in such manner as to iorm substantially a
a.
iorming the sheet, and circulating a gaseous around the rising sheet, and thereaiter permit
medium in contact with and transversely oi the tingthesheettocool.
12. Apparatus ior drawing sheet glass com
e oi the sheet toward the
' sheet irom 3one
other edge thereof 'hile the temperature oi the ‘ prising a slotted member, means to draw molten
sheet is above the lower limit \oi the-annealing glass, upward from said slot,. a cooler spaced
above
member, parallel with and atone
range.
‘
4. In the method ciiorming a glass sheet by side oi said slot, and means to create a current
‘continuous drawing irom a tank containing a_ oi gas substantially parallel with said slot and
bath oi l-molten glass, the steps consisting in between said member and said cooler.
dium in contact with and transversely oi the, prising a glass furnace extension, a slotted mem
sheet from one edge of the’ sheet toward the bet at the surface of the glass in said extension,
other edge thereoi while the temperature oi the ~ means to‘ draw glass upward from said'slot, a
cooler spaced above said slotted member and ad
sheetis above the anneaiing'range.
.
‘ 5. In the method oi iorming a glass sheet by ‘iac'ent' to and parallel with each iace oi‘ the drawn
continuous drawing irom a tank containing a glass, and means to create a substantially hori
bath oi molten glass. the steps consisting in ‘ zontal current'ci gas along the space between
iorming the sheet, and circulating a gaseous me- ‘each cooler and- the slotted member and sub
\
_
dium in contact with and transversely oi thev stantially parallel with said slot.
it. In the method oi iorming a glass sheet by
sheet irom one edge. oi the sheet toward the
;other edge ‘thereoi while the temperature oi the " continuous drawing from a tank containing a
bath oi molten glass and in a vertically extend- '
sheet is substantially at the‘setting range.
6.
the method ‘oi forming‘ a glass sheet by ing direction through the drawing pit, the steps
continuous drawing from a ‘tank containing-a ecompriaing iormingthe sheet, and circulating a
‘ bath' oi molten glass, the steps‘ consisting in . gaseous‘ medium in’ the pit transversely oi the '
iorming the sheet, and circulating a gaseous me
diumin contact with and transversely oi the
sheet irom one edge oi the sheet toward the
' 15. The process oi drawing glass, which con
sists in drawing glass upward from a suitable ‘
other edge thereoi while the temperature oi the source oi molten glass,'stretching the glass, as
sheet is'substantially‘at the setting range, and ' it is drawn upward,‘ to a sheet of suitable thick- ‘'
nose, while contacting the 'suriaces oi the sheet‘
also while the temperature oi the sheet is sub
stantially at the annealing range.
'
> ' with gases, cooling thé’glass during said draw
reby'terminating the stetching oi the
'i. In the method oi iorming a glass sheet by ing and
continuous drawing from a‘ tank containing a
bath oi molten glass, the steps consisting in
iorming the sheet, and
a gaseous me
glass, an “producing currents in the gases ad- ‘
iacent to and substantially parallel with the line 70
oi said source, whereby gases must cross said cur
dium in contact with and‘ transveraeiy oi the’ rent toreach the suriaoe oithe
sheet substantiallyat the meniscus.
Apparatus icr drawing sheet glass com,- '
8. In the method oi 'iorming a glasssheetby
mea‘ns for providing aipool oi molten *
= continuous'drawing‘irom a tank containing va ~
i
4
2,116,698
‘
glass, a slotted member at the surface of the glass, v of molten glass, ‘stretching and cooling the sheet
while surrounding it with gases, and producing
slot, and means to produce a current of gas ?ow- a current of said gases adjacent to and parallel
ing horizontally along each side of the drawn with said source‘on at least one side thereof,
glass immediately above said slotted member.
whereby gases cross said current to reach the 5
17. The process. of drawing sheet glass, which 7 surface of the glass during its stretching.
' means to draw. a sheet of glass upward from said
‘consists in drawing a sheet upward from a source
}
FEEDER-IO L; BISHOP. _
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