Note: Descriptions are shown in the official language in which they were submitted.
P~30~a ~0~ ;3
This invention relates generally to furnaces, and is
particularly concerned with furnaces for heat treating glass in
a glass tempering system.
Examples of prior art furnaces are disclosed in U.S.
Patent Nos. 1,787,307; 2,215,322; 2,265,027; 2,370,381; 2,551,311;
3,295,843; 3,427,011; 3,470,624; and 3,516,649.
The tempering of glass sheets by first heating the
sheet and then suddenly cooling the heated sheet increases the
mechanical strength of the glass sheet, which, in and of itself,
increases the safety and the use of the glass. In addition,
however, the safety is increased because the tempered glass,
when broken, disintegrates and shatters into small, relatively
dull and harmless particles instead of into large sharp slivers
as is the case with untempered glass.
Conventional glass tempering processes include systems
wherein untempered glass sheets are suspended by tongs on a
carrier. The carrier with the sheets supported thereon are
then conveyed into a furnace and heated to a desired temperature,
, after which the carrier with the heated sheet is conveyed to a
blasthead or quenching apparatus to suddenly cool and reduce the ~-
temperature of the glass to complete the tempering process.
During the heating of the glass in the furnace, if dif-
ferent portions of the glass sheet are exposed to uneven temper-
atures, the resulting stresses can cause warpage or breakage of
~` 25 the sheet. It is also desirable during the cooling process that
the glass sheet be uniformly bathed by the cooling fluid (see,
for example, the aforementioned U.S. Patent 2,724,215). As the ~ -
; sheet being treated is conveyed from one stage to the other of ;~
; the process, it is of course undesirable for any of the moving
parts to strike obstructions and cause breakage or mechanical
--1-- r .~
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P- 3 0 6A 1~ 63
damage to any of the components and parts of the system. It is
of course also desirable to maintain a high rate of production
with the glass tempering system.
The present invention is for a furnace for heat treating
glass sheet material and the like comprising: a furnace enclosure
having top, bottom and side walls of refractory material; a parti-
tion dividing the interior of said furnace enclosure into first and
second zones; heating means in both of said zones; and gas treat-
ing and distributing means in said first zone; said gas treating
and distributing means including an intake chamber communicating
with a low temperature area of said second zone and with ambient
atmosphere, a discharge chamber communicating with an area of -
` said second zone spaced from said low temperature area with which
said intake chamber communicates, at least a portion of the heating
means in said first zone being located in said discharge chamber,
and blower means including at least one blower having its intake
side connected with said intake chamber and its discharge side
connected with said discharge chamber; said gas treating and dis-
- tributing means being operable to (1) draw gas from a low tempera-
20 ture area of said second zone into said first zone, (2) draw am- -
'~ bient gas from the exterior of said enclosure into said first
zone, (3) mix the exterior gas and gas from said second zone to
; provide a substantially homogeneous temperature throughout the
mixed gases, (4) heat the homogeneous mixture of gases, and (5)
; 25 force the heated, homogeneous mixture of gases into said second
zone.
- According to another aspect of the invention, a partition
extends transversely between the top and bottom walls of the fur-
nace, said second zone being defined between said top wall and
30 said transverse partition, and said first zone bein~ defined be- ~
:' :
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P-306A 1~463
tween said bottom and said transverse partition. The peripheral
edge of the transverse partition is spaced from the inner surface
of the side wall of the enclosure, and a plurality of vanes are
seated on said transverse partition and span to gap between the
peripheral edge of said transverse partition and the inner side
wall of said enclosure to define a series of slots.
An opening in the transverse partition spaced inwardly
from the peripheral edge thereof provides communication between the
low temperature area of the second zone and the intake chamber.
The discharge chamber communicates with the second zone through
the slots.
According to another aspect of the inventiDn, the fur-
nace has a motor for said blower mounted externally of said fur-
nace enclosure; a shaft opening in said side wall; the shaft of
said motor extending through said shaft opening to drive said
blower; said shaft opening being larger than said shaft and said
shaft being in non-sealed relationship with said shaft opening
' such that outside, ambient gas is drawn through said shaft opening.
Also according to the invention, the gas treating and
distributing means includes a chimney extending between said bottom
wall and the lower surface of-said transverse partition, the lower -
end of said chimney communicating with ambient atmosphere, the ~-
. . ': '' '-
walls of said chimney defining the inner walls of said intake --
chamber; a vertical wall surrounding said chimney and spaced be-
tween said chimney and the side wall of said enclosure and extend-
ing between said bottom wall and said transverse partition to
define the outer wall of said intake chamber. ~ -
; A furnace according to the invention may also include at -~ -
; least one opening in the wall of said chimney connecting the interi-
30 or of said chimney with said intake chamber so that ambient gas is ~-
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P-306A ~ ~3
drawn into said intake chamber through the opening in said chimney
during operation of said blower, and an adjustable damper in said
chimney for controlling the rate of flow through said chimney.
A furnace according to the invention may also include a
5 ramp in the discharge chamber having a lower end and an upper end
spaced from said lower end, the lower end being disposed adjacent
the discharge opening of the blower at the lower side of said dis-
charge opening, and the upper end being spaced along the length of
said discharge chamber from said lower end and nearer to said slots
10 than said lower end for deflecting gases from said blower toward
said second zone.
A furnace according to the invention may also include an
inlet and an outlet in the side walls and a slot in the top wall;
and an housing overlying said slot and defining a pressure chamber
15 in communication with said slot. The 'urnace may further include
means for supplying fluid pressure to said housing to provide a
~ fluid pressure barrier at said slot in the top wall to resist es-
-; cape of gases from said furnace through said slot, the pressure ofthe gases in said chamber also providing a resistance to the flow
; 20 Of fluid pressure from said housing into said furnace through said
slot.
According to another aspect of the invention, the furnace
may further include an external enclosure extending across the top
wall of the furnace enclosure and overlying said slot, said external ~`--
25 enclosure extending through said housing and being in fluid communi- ~ ~
cation with the pressure chamber defined by said housing. -
A furnace according to the invention may further include
inlet and outlet doors for said inlets and outlets, respectively;
J a pair of air curtain openings in said external enclosure; the tops
30 of said doors being disposed beneath and in the path of said air
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P-306A 1~4~463
curtains in their respective closed position such that the air cur-
tains impinge on the tops of the doors, when said pressure chamber
is pressurized, to reduce the leakage of gases from within the fur-
nace at the tops of the doors.
Also according to another aspect of the invention, the
side walls of the furnace may have an outer insulating layer and an
inner layer of material having a low coefficient of thermal expan-
sion; said inner layer having spaced end portions projecting be-
yond the outer layer and the periphery of the side walls to define
said inlet and outlet openings.
Each of the doors for the furnace may comprise an elon-
gated support bar, a plurality of blocks of refractory material
supported on said bar in end-to-end relationship, and means adjust- `
ably securing each of said blocks to said bar to accommodate irregu-
lS larities in the opening controlled thereby.
Other objects, advantages and features of the inventionwill become apparent from the following description taken in con-
nection with the accompanying drawings in which:
FIGURE 1 is a plan view of an entire system for treating -
~
glass sheet material and the like embodying the invention;
FIGURE 2 is a top plan view, partially in section, of a
heat treating furnace embodying the invention and of the type that
; may be used in the system shown in FIGURE l;
FIGURE 3 is a sectional elevational view of the furnace ~ -~
of FIGURE 2 taken on lines 3-3 of FIGURE 2;
FIGURE 4 is a sectional elevation~ view of the furnace
of FIGURE 2 taken on lines 4-4 of FIGURE 2; -
FIGURE 5 is a sectional view taken approximately on
lines 5-5 of FIGURE 3;
FIGURE 6 is a sectional view taken approximately on
lines 6-6 of PIGURE 5; --
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P-306A
FIGURE 7 is an elevational view of one of the furnace
doors as viewed on lines 7-7 of FIGURE l;
FIGURE 8 is a detailed view of one segment of the fur-
nace door as viewed on lines 8-8 of FIGURE 7;
FIGURE 9 is a sectional view taken along lines 9-9 of
FIGURE 7;
; FIGURE 10 is a composite sectional view illustrating
the drive conveyor with a sheet of glass located within the fur-
nace along lines 10-10 of FIGURE 2, and also illustrating in
phantom lines a portion of the blasthead nozzle in a different
plane;
FIGURE lOa is a sectional view of channel-shaped return
rails for the drive conveyor chains and friction material in the -
, return rails being applied to the peripheries of the rollers of
15 the chain; and -
FIGURE 11 is a sectional view of the furnace top similar
to FIGURE 10 illustrating another form of conveyor and conveyor '
cooling system embodying the invention.
FIGURE 1 illustrates a system including a treatment zone - -
' 20 for glass sheet material and the like comprised of a furnace col-
lectively designated by reference character A and a blasthead col- --~
lectively designated by reference character B. A loading station
C is defined at one end of the treatment zone, and an unloading -.
.' ~
' station D is defined at the other end of the treatment zone. Glass
' 25 sheets to be tempered by the furnace A and blasthead B are loaded
onto a conveying system at the loading station C and are removed ;-
from the conveying system at the unloading station D after the -~
tempering operation is completed. The conveying system includes
a drive conveyor designated collectively by reference character E
extending from the loading station C through the treatment zone to
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P-306A 10~4463
the unloading station D, and a return conveyor F. The glass sheets
G (FIGURES 3 and 4) are suspended from carriers designated collec-
tively by reference numeral 2 by a plurality of tongs 4. The tongs
4 may be of conventional construction, several types of such tongs
being disclosed in the above-referred to U.S. Patents. The glass
sheets G are placed on the carriers 2 by the tongs 4 at the loading
station C, and the drive conveyor E moves the carrier 2 with the
glass sheet G suspended therefrom through the treatment zone to the
unloading station D in a manner set forth in greater detail below.
When the treated sheet of glass G iS removed from the carrier 2 at
the unloading station D, the return conveyor F carriers the carrier
2 from the unloading station D to the loading station C for another
treatment cycle.
The construction of the furnace A is illustrated in de-
tail in FIGURES 2 through 9. As shown in FIGURES 3 and 4, the fur-
nace A comprises an enclosure having a top wall 6, a bottom wall 8, -
and a side wall 10. The top and side walls 6 and 10 are formed of
an outer, insulating layer 12 of refractory material and an inner
layer 14 of firebrick or other refractory material. The layers 12 ~-1
and 14 may both be of castable material. The inner layer 14 of the
side wall 10 are formed integrally with outwardly projecting T-sec-
tions 16. Adjacent pairs of the T-sections 16 form supports for ~ -
electrical heating elements 18. The elements making up the layers
12 and 14 are cast with appropriate openings and recesses for re-
25 ceiving rod connectors 20 of conventional construction for securing --~
the layers 12 and 14 together, and to the shell lOa. --
: A transverse partition 22 (FIGURES 3 and 4) is spaced --
between the top and bottom walls 6 and 8 and divides the interior -
of the enclosure into a first, or lower gas or air heating zone 24,
and a second, upper glass heating zone 26. The heating elements
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P-306A 104~463
18 in the side wall 10 are located in both the lower and upper zones
24 and 26, respectively.
As pointed out in greater detail below, gas or air treat-
ing and distributing means is located in the first, lower zone 24
which is operable to (1) draw relatively low temperature gas from
the lower portion of the second, upper zone 26 into the lower zone
` 24, (2) draw ambient air or other gas from the exterior of the fur-
nace A into the lower zone 24, (3) mix the exterior gas and the gas
drawn from the upper zone 26 to provide a mixture having a substan-
tially homogeneous temperature throughout, (4) heat the homogeneous
mixture of gases, and (5) force the heated, homogeneous mixture of
gases into the second, upper zone 26 along the side wall to help
: maintain a uniform, tempering temperature on the glass sheet G lo-
cated in the upper zone 26, and to pressurize the upper zone. -
The entire periphery 28 of the partition 22 is spaced
from the inner side wall of the enclosure, and a plurality of vanes
30 in the form of blocks of refractory material are seated on the
edge of the partition and span the gap between the peripheral edge -
28 and the T-sections 16. The vanes 30 are spaced from each other
to define a series of slots 32 at the periphery of the partition 22.
The vanes 30, as shown in FIGURE 3, have a lip which seats on the
: upper edge of an upstanding wall 34 formed by firebrick or other .
refractory material around the periphery of the partition 22, ex-
cept at the central portion thereof in which are mounted additional
horizontal heating elements 18 (FIGURES 2 and 3).
Spaced inwardly from the periphery of the partition 22
are openings 36 for providing a passage for the gases from the
lower portion of the zone 26 into the lower zone 24.
Defined in the lower zone 24 is an intake chamber 38 and .
a discharge chamber 40. The openings 36 ccmmunicate with the in-
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P-306A 1a 4 ~ 46 3
take chamber 38, and the slots 32 communicate with the discharge
chamber 40.
A chimney 42 extends between the bottom wall 8 and the
transverse partition 22. The chimney 42, in the illustrated embodi-
ment, is enclosed by a rectangular wall 44 which also defines theinner walls of the intake chamber 38. The lower end of the chimney
communicates with ambient atmosphere, and an adjustable damper 46
is mounted in the chimney near the lower end thereof. The damper
is adjusted by a handle 47 tFIGURE 5) mounted on the end of a rod
49 extending through the lower side wall of the furnace. A verti-
cal wall 48 surrounds the chimney 44 and defines the outer wall of -
the intake chamber 38 and the inner wall of the discharge chamber -
40. The outer wall of the discharge chamber 40 is defined by the
side wall of the furnace enclosure.
A plurality of blowers 50 are mounted in the discharge
chamber 40. In the illustrated embodiment, four such blowers are
; located within the discharge chamber 40 (FIGURE 5). In the illus-
trated embodiment, the blowers are conventional scroll type blowers
driven by motors 52 mounted externally of the furnace enclosure.
In the illustrated embodiment, as shown in FIGURE 3, each motor 52
drives the shaft 56 of its respective blower through gearing 54. - --
The shaft 56 of the blower extends through an opening 58 in the
side wall of the furnace enclosure. The opening 58 is of greater -
diameter than the shaft 56, and the shaft 56 is in unsealed rela-
tionship with the opening 58 so that operation of the blower draws
ambient air through the opening 58 into the blower. The blower 50 -
also has its intake side connected with the intake chamber 38 . -
through an opening 60 formed in the wall 48. Each of the blowers
50 has its discharge opening 62 directed along the length of the ~ -
discharge chamber 24. As shown in FIGURE 6, a ramp 64 extends from
, . , , ., , . , , ,. : , ;: ,, . . . , . .: . . . ..
P-306A lfJ~ 6 3
the lower end of the discharge opening 62 of one blower upwardly to
the adjacent, downstream blower 50. The ramp 64 thus has its lower
end disposed adjacent the discharge opening of the blower on the
lower side of the discharge opening 62, and its upper end spaced
from the lower end along the length of the discharge chamber and
nearer to the slots 32 for deflecting the flow from the blower
toward the slots into the second, upper zone 26.~ .
As shown in FIGURES 3 and 4, a plurality of openings 66
are provided at the upper end of the chimney 42. Hence, operation
of the blowers draws air through the chimney 42 and openings 66
into chamber 38 as well as from the upper zone 26 through openings
36 to the intake sides of the blowers 50. The ambient air from the -.
chimney 42 and the openings 58 surrounding the shafts 56 of the
blower is mixed with the higher temperature gases drawn through
the openings 36 from the upper glass treating zone 26. The action
of the blowers in the lower zone 24, together with the arrangement .
~. of the chimney, intake chamber and discharge chamber, as well as
; the ramp 64, thoroughly mixes and homogenizes the air or other
:~ gases in the lower zone 24 to provide a substantially uniform tem-
-~ 20 perature of the gas discharge through the peripheral slots 32 past
the heating elements 18. The vanes 30 deflect the gases upwardly
in the direction of the arrows 62 (FIGURE 3) and reduce the spiral- .
`` ing, turbulent motion of the gas discharge from the blowers 50.
The gases are additionally heated by the heating elements
f 25 18 in the lower zone 24 at the slots 32 so that the heated gas .~ -
rises along the-heating elements 18 in the side wall of the upper
: zone 26 toward the inner surface of the top wall 6. The gases then
circulate inwardly toward the glass sheet G and then downwardly to
the openings 36. The circulation is such as to provide a minimum
. 30 amount of turbulence and a minimum amount of temperature differen-
-- 10 --
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P-306A 1t)44~63
tial along the surface of the glass sheet G during the time that it
is disposed in the furnace A, as well as to reduce the temperature
differential over the inner surfaces of the upper zone 26. Thus,
the heated gases from the lower zone 24 are forced upwardly along
the periphery of the glass treating zone 26 to be exposed directly
to the electrical heating elements 18 located in the side wall 10,
and are drawn through the intake chamber 38 by the blowers at a
location spaced inwardly from the side wall 10 so that the gases
move downwardly along the surfaces of the glass sheet G. As pointed
out previously, the vanes 30 reduce the turbulence of the gas flow-
ing into the upper zone 26 from the lower zone 24 and deflect the
gases upwardly in a slightly spiral path. -
The electrical heating elements 18 in the lower and upper
zones 24 and 26 are controlled by a differential air heat controller -
72. The controller 72 responds to the temperature differential be-
tween the slots 32 and the upper zone 26 as sensed by a pair of
thermocouples 68 and 70. The thermocouple 68 is disposed in the -
upper zone 26 and the thermocouple 70 is disposed in the slot 32.
If a temperature differential is sensed by the controller 72 as a
result of a low temperature condition at thermocouple 70, additional
energy is supplied to the heating elements 18 in the lower zone 24
to reduce or eliminate the temperature differential. The tempera-
` ture of the upper zone 26 is controlled by a separate thermocouple ~ -
,~,
and temperature controller (not shown). ~ ~ _
In order to permit the glass sheet G to move through the
furnace, diametrically opposed openings 74 are formed in the side
wall 10. Similarly, a slot 76 extends between the openings 74 in
the top wall 6 to permit the carrier 2 to pass through the furnace. -~
With reference to FIGURE 9, the inner layer 14 of the silica ma-
terial has end portions 78 which project beyond the insulating
,;
A
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P-306A 1044463
layer 12 and define the opening 74. The illustrated furnace A, as
shown in FIGURES 2 and 5, is of substantially circular cross-section.
Hence the inner layer 14 comprises two semi-circular sections in
cross-section with outwardly curved and slightly thickened portions
80 terminating in the end portions 78 projecting beyond the peri-
phery of the side wall 10. The space between the end portions 78,
as pointed out previously, defines the opening 74 through which the
vertically suspended glass sheet passes to enter into or exit from
the furnace. Due to the low coefficient of thermal expansion of
the silica material 14 held to the shell lOa by rod connectors 20,
the surfaces surrounding the opening 24 maintain a constant shape
at all temperatures. The T-sections 16 are also formed with out- :
wardly curved end portions 82 conforming to the configuration of
portions 80. The heating elements 18 additionally have outwardly
curved portions 84a terminating at the opening 74 so that heat
losses through the opening 74 are minimized when the opening is un-
covered.
As pointed out previously, heating elements 18 are also -
provided in the top wall 6 on each side of the slot 76 (FIGURE 3)
l 20 to minimize heat losses through the slot 76. Additional heating
elements 18 may, if desired, be mounted in the lower surface of the
partition 22 at the upper end of the chimney 42 to add heat to the
air in chimney 42 before it passes through the openings 66.
The openings 74 on the inlet and outlet sides of the fur-
; 25 nace A are each controlled by doors which may be of identical con-
struction. The constructiOn of one of the doors is illustrated
in detail in FIGURES 7, 8 and 9. Reference numeral 84 collectively
designates a door movable between open and closed positions with
respect to the opening 74 and which is made up of a plurality of
segments 88, each adjustably secured to an elongated support bar 86.
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P-306A ~44463
Each of the segments 88 is comprised of a block 90 of
ceramic or other refractory material, which material may be the
same as the material of layer 14, supported in jackets or sheaths
92 of metal such as steel. The jackets 92 each include outwardly
projecting support bar flanges 94 and inwardly projecting block
engaging flanges 96 (FIGURE 9). The flanges 96 are received in
slots formed in the respective blocks 90 to secure the blocks to
the jackets 92. The flanges 94 are formed with elongated slots
98, and conventional bolts 100 are inserted through openings in
the support bar 86 aligned with the slots 98 to secure the segments
88 individually to the support bar 86. The slots 98 permit the
segments to be individually adjusted with respect to the support ,
bar 86 to accommodate any irregularities in the surfaces of the
projections 78 with which the door is engaged when it is in the -~
closed position as shown in FIGURE 9 so that each segment 88 may
have as tight a fit as possible with the projections 78 to assure
a minimum loss of heat when the doors are closed.
Two of the segments 88 are designated in FIGURE 7 by
reference numerals 88a and 88b. Door actuating arms 102 are se- ;
cured to the support bar 86 at segments 88a and 88b. The actuating
arms 102 are each welded to plates 104 which in turn are secured - :
by conventional bolts 106 to the support bar 86. Slotted openings
are provided either in the support bar 86 or plates 104 to permit -
adjustment of the segments 88a and b in the same manner as the re-
maining blocks 88. The actuating arm 102 is pivotally connected
at spaced points to the ends of parallel links 108 and 110. Link
108 has its other end nonrotatably secured to a rod 114, and link
110 has its other end nonrotatably secured to a rod 112. Rods 112
and 114 are rotatably supported at their upper end to a bracket -
116. Rod 112 is rotatably supported at its lo~er end in a bracket
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P-306A ~ 6~
120 and rod 114 is rotatably supported at its lower end in a brac-
ket 118.
The door 84 is moved between its open and closed posi-
tions by a hydraulic ram 122 having its cylinder end pivotally con-
nected at 123 to a bracket 125 and its piston end pivotally connect-
ed to an operating lever 124 nonrotatably secured to rod 114. When
the ram 122 is retracted from the position shown in FIGURES 7 and 9,
the links 108 and 110 pivot about the axes of the respective rods
114 and 112 in a counterclockwise direction to move the door 84
away from the opening 74.
In summary, FIGURES 3 through 9 illustrate a furnace
having a substantially circular cross-section with a plurality of
blower units 50,52 disposed about the periphery of the furnace in a
~; zone below and separated from the glass treating zone 26. Make-up ~;i
air can be supplied through the rectangular chimney 42 at its
openings 66 in addition to recirculating the air from the glass
-~ treating upper zone 26 past the heating elements 18 at the sides
of the furnace. Furthermore, the layer or blocks 14 of material at
the top or roof of the furnace is also integrally formed with T-
sections 16 forming grooves into which the elongated heating ele-
ments 18 at the roof of the glass treating zone 26 can be slipped
` into and secured into place. When the blowers are operating, make-
up air can be drawn into the furnace through openings 46a at the
; lower end of the chimney 42 at a rate depending upon the position
of the adjustable damper 46. The ramps 64 associated with the
blowers 50 (FIGURE 6) serve to mix and recirculate the air upwardly -
and tangentially toward the return passages defined by the slots 32, : -
while the vanes or blocks 30 deflect the recirculated air verti- -
cally and somewhat tangentially along the side walls of the furnace
30 and the heating elements 18 located at the side walls. The open- -
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1~)44463
P-306A
ings 58 surrounding the blower shaft also prevent overheating of
the blowers when the blowers are not operating because the chimney
effect causes outside air to always be drawn through the openings
58 to cool the blowers.
Again referring to FIGURE 3, reference numeral 126 desig-
nates a collection tray suspended from the top or roof 6 of the fur-
nace by rods 128. The tray 126 collects any pieces of glass that
are broken during the heat treating process and facilitates removal
of the broken glass from the furnace and prevents the pieces from
falling into places of difficult access in the furnace.
With reference primarily to FIGURE 10, the drive conveyor
for moving the carrier 2 from the loading station through the treat-
ment zone (furnace A and blasthead B) includes a pair of spaced
parallel rails 188 extending from the loading station C to the un- -
! 15 loading station D. The rails 188 are each seated on a strip 188a,
the strips 188a being spaced from each other but having their opposed
, inner edges projecting over the slot 76 so that a smaller slot is
t defined between the strips 188a. FIGUÆ 10 illustrates the portion -
of the conveyor located on the roof or top 6 of the furnace. The
` 20 drive conveyor further includes a pair of endless, flexible members
190 each having an active run slidably supported on one of the rails.
' The endless, flexible members 190 are in the form of a chain having
? links 192 and rollers 194. The diameter of each of the rollers is
. .
j greater than the width of the links so that the rollers support the
25 active runs of the chains 190 on the respective rails 188, and the -
upper peripheries of the rollers project beyond the upper edges of `-
the links.
Each of the carriers 2 comprises a pair of slide members -
196, which, as shown in FIGURE 10, is supported on the rollers 194
of the chains 190 and extends across the space between the rails
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P-3o6A 104~463
188. Depending from each slide member is a suspension member 198
which extends through the slot between the rails. A material sup-
porting bar 200 is supported on the suspension member 198, and the
tongs 4 are mounted on the material supporting bar 200. As shown
in FIGURE 10, the suspension member 198 also extendsthrough the
slot 76 in the top wall 6 of the furnace, and the material sup-
porting bar 200 is received in the furnace.
With the slide members 196 supported on the peripheries
of the rollers 194, and the rollers 194 also supported on the rails
188, advancement toward the right as viewed in FIGURE 4 causes the
rollers 194 to rotate about their respective axles 195, which
axles also form the pivotal connection between the ends of the
links 192. In other words, the links 192 are pivotally connected
in end-to-end relationship by the axles 195 of the adjacent rollers.
The rotation of the rollers 194 causes the slide members 196 to
move toward the right due to the frictional engagement between the
slide members and the rollers 194 on which the slide members are
' supported, and only the links 192 are supported on the axles.
~ Furthermore, with no slippage between the rollers and slide mem- ---
$ 20 bers, the slide members 196 move twice as far as the links 192. -
The active runs of the drive conveyor chains on which - -
the slide members 196 are supported extend through an enclosure
. - -: .
228. As shown in FIGURE 10, the enclosure 228 includes inner and
outer side walls 232 and 234, and a top wall 236 extending between -
: . .. 25 the side walls 234. The enclosure 228 closes the slot 76 in the
top wall of the furnace to act as a seal to prevent hot gases from
escaping from the furnace. The portion of the top wall 236 of the -
enclosure 228 that extends across the top of slot 76 is formed with ~ ;
a plurality of openings 230 for the admission of air or other cool-
30 ing fluid to reduce the temperature to a level commensurate with ;~
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P-306A 10~463
maintaining proper lubrication of the axles of the rollers 194.
` The admission of air under pressure through the openings 230 pres-
surizes the enclosure 228 to further prevent the escape of hot gases
from the furnace through the slot 76.
As shown in FIGURES 4 and 10, a housing 237 is mounted on
the portion of the enclosure 228 that extends across the top of the
furnace and overlies slot 76. The housing 237 has ends 237a (FIG-
URE 4) and defines a cooling chamber 237b connected with a blower
239 for supplying the chamber 237b with cooling air and pressuriz-
~ 10 ing the chamber 237b. The cooling air from chamber 237b is admit-
`~ ted into the enclosure 228 through the openings 230. A pair of
slots or series of openings 241 are formed in the top wall 236 of
the enclosure. The slots or openings 241 extend substantially the
entire width of the top wall 236 and are inclined downwardly and
i 15 inwardly at locations overlying the upper ends of the doors 84 when
the doors 84 are in their closed positions. The slots or series
of openings 241 are smaller than the openings 230 so that the velo-
city of air flowing through slots 241 from chamber 237b into the :
enclosure 228 is greater than the velocity of the air flowing -
20 through openings 230. Consequently, a continuous air curtain 243 ~
is formed by the air flowing through slots 241, which air curtain ~ '
extends throughout the width of the enclosure 228. The air curtains ;
243 help to confine the air in the enclosure 228 between the slots ~
241 and maintain a pressure over-the slot 76 from the blower 239 -
25 that reduces the flow of hot gases upwardly through slot 76 from ,-
the furnace. The slots are also inclined downwardly and inwardly `-
, so that the air curtains 243 impinge on the upper ends of the ;
doors 84 in their closed positions to thus reduce the leakage
through any gaps between the tops of the doors and the furnace.
In order to maintain adequate frictional engagement be-
''. ''
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A :
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P-306A ~O~ 4 6 3
tween the rollers 194 and the slide members 196, the system includes
~ means for applylng friction material to the peripheries of the rol-
- lers to reduce slippage between the rollers and the slide members. -i
The means for applying friction material includes the channel-
shaped return rails 206 with powdered friction material received
therein as illustrated in FIGURE lOa. The inactive run of the
chain on its return movement to the loading station end of the drive
chain passes through the channels 206 and the powdered friction ma-
terial contacts and adheres to the peripheries of the rollers. The
powdered friction material is indicated by reference numeral 240 in
FIGURE lOa and may be plaster of paris or similar material. The
powder 240 also serves to remove lubricant from the peripheries of
the rollers 194 to reduce the slippage between the rollers and the
slide member 196.
In operating of the entire system, a plurality of the
carriers 2 are mounted on the conveying means E and F. When the
system is started into operation, the return conveyor chain 252
runs in phased relationship with the drive conveyor chain 190 which
advances a selected distance at timed intervals. -
When a carrier 2 is pushed onto the loading station end ~ -
of the drive conveyor E by the return conveyor chain 252, an opera-
tor can secure glass sheets to be treated to the tongs 4 on the ma-
terial supporting bar 200. The glass sheet G can be secured to
the carrier 2 during the dwell period of the drive conveyor, how-
ever, should additional time be needed to complete securing of the
sheet to the carrier, the operator can prevent the carrier from
advancing with the drive chain 190 by simply holding the carrier
against movement and letting the chain override the slide members
196 of the carrier. When a sheet is loaded onto the carrier, and
30 the dwell period ends, the doors 84 of the furnace open and the -
- 18 -
'.~'
P-306A 10~463
carrier is conveyed onto the furnace through the opening 74 on the -
inlet side of the furnace by the drive chain 190. The carrier is
conveyed into the furnace into the position shown in FIGURE 4 where
it stops for another dwell period. When the carrier reaches the
position shown in FIGURE 4, the doors 84 close and the glass sheet
G is heated to its tempering temperature. At the end of the dwell
period, the doors 84 open, and the carrier 2 within the furnace is
conveyed through the opening 74 on the outlet side of the furnace
A into the space between the blasthead nozzles 166, which nozzles
are illustrated in phantom lines in FIGURE 10. The carrier 2 re-
mains in the blasthead for the next dwell period. The glass sheet
G and carrier 2 is then conveyed by the drive conveyor from the :
blasthead ~ to the unloading station D for removal of the glass
sheet G from the carrier by an operator. The carrier is then in
15 a position to be engaged by a return conveyor chain 252 and is con- ,
veyed back to the loading station C.
FIGURE 11 illustrates an alternative construction for the
drive conveyor and conveyor cooling system. The drive conveyor of
FIGURE 11 includes a pair of chains 390 identical to the chains 190
20 of the previously described embodiment. A pair of spaced parallel- -
rails 388 (FIGU~E 11) each support the upper, active run of the
chains 390. The chains 390 each include links 392 and rollers 394.
The links 392 are connected in end-to-end pivotal relationship by
pins 395 forming the axles for the rollers 394. - - -
The lower, inactive runs of the chains 390 extend through ~ -
tubular return guide members 404. As shown in FIGURE 11, the tubu-
lar return guide members 404 are seated on the strips 188a and com- :
pletely enclose the return or inactive runs of the chains 390. The
guide members 404 are of square or rectangular cross-section as
shown in FIGURE 11 and are secured by connectors 408 to the outer
,~ -- 19 --
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P-306A 1044463
side walls 410 of an enclosure 412 for the upper, active runs of
the chains 390. The enclosure 412 extends from the loading station
through the treatment zone to the unloading station.
The enclosure 412 includes a top wall 414 extending be-
tween the outer side walls 410 and a pair of spaced, inner sidewalls 416, the rails 388 each being located between adjacent pairs
of the outer and inner side walls 410 and 416, respectively.
The portion of the enclosure 412 that extends across the
treatment zone is received in a housing or shroud 418. The shroud
418 has a top wall 420, side walls 422 extending downwardly from
the top wall, and bottom walls 424 extending inwardly from the lower
ends of the side wall 422 and seated on the strips 188a. The bottom
walls 424 have upturned, inner flanges 426 engaging the sides of ~ :
the tubular guides404, the upper ends of the guide members terminat-
ing beneath spacers 428 at each of the connectors 408. The shroud
or housing 418 has end walls which are located approximately in the
same position with respect to the furnace doors 84 as the end walls
237a of the housing 237 of FIGURE 4.
The housing 418 is connected through conduit 432 with a ~-~
blower 324. The housing 418 defines a pressure chamber 436 for
supplying cooling air (or other fluid) to the portions of the
chains 390 passing over the slot 76. The pressure in chamber 436 -
also acts against the pressure in the furnace to reduce the loss
of heat through slot 76. The pressure in chamber 436 tends to
25 balance the pressure in the upper heating zone 26 of the furnace
so that there is a minimum amount of transfer of fluid through slot
76 in either direction.
Formed in the outer side walls of the tubular guide mem-
bers 404 is a series of openings 438. The series of openings 438 -
extends throughout the length of the tubular guide members 404
' '
~- 20 ~
P-306A 1~ ~ 4 46 3
that is enclosed by the housing 418. Similarly, a series of open-
ings 440 are formed in the top wall of the guide members 404 along
the lengths of the guide members enclosed by the housing 418. A
series of openings 441 are also formed along the lengths of the
rails 388, and each of the openings 440 is aligned with one of the
openings 441. Consequently, air from the chamber 436 flows through
the openings 43~, 440 and 441 to the enclosure 412. The cooling
air from the blower 434 is under pressure, and flows into the space --
between the inner side walls 416 of the enclosure 412 as is indicat-
ed by the arrow 444 in FIGURE 11, and the pressure acts downwardly
as indicated by the arrows 446 toward the slot 76. As a result, a
pressure boundary is provided between the cooling air from the
blower 434 and the hot gases from the heating zone 26 of the fur-
nace at the slot 76. The chains 390 are thus not subjected to the
high temperature from the furnace, and consequently, adequate
lubrication can be maintained between the rollers 394 and their
respective axles 395 since the blower 434 is able to maintain a
sufficiently low temperature on the chains to prevent loss of lub-
rication. As in the previously described embodiment, friction ma-
terial such as plaster of paris may be provided in the tubular
` guide members 404 to remove any lubricant from the peripheries of -
the rollers 394 and also to reduce the slippage between the rollers -
394 and slide member 196 as the carriers move through the furnace. -
While specific forms of the invention have been illus-
trated and described in the foregoing specification and accom-
panying drawings, it will be apparent to those skilled in the
- art that the invention is not limited to the exact construction
shown, and that alterations and modification in the contruction
; and arrangement of parts, all falling within the scope and spirit
of the invention, can be made by those skilled in the art.
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