Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITLE
! TEMPERATURE CONTROLLED DISTRIBUTOR BEAMFOR CHEMICAL VAPOR DEPOSITION
BACKGROUND OF THE INVENTION
The invention relates generally to an apparatus for
coating glass and, in particular, to a temperature controlled
distributor beam for chemical vapor deposition on glass.
One method of coating flat glass is by contacting the
glass with a gaseous coating material at substantially
atmospheric pressure. However, it has been difficult to
achieve uniform coatings on a moving glass ribbon by known
techniques. In U.S. patent No. 3,850,679, it is proposed to
enhance the uniformity of films produced by chemical vapor
deposition by directing coating gas onto the glass surface
through a nozzle at a Reynolds number of at least 2,500. For
speed coating a continuous ribbon or sheet of glass, a
A ~ Reynolds number of at least 5,000 for the fl ~ing gas is
4 recommended. The use of a Reynolds number ~a~ 2,500 means
that the gas flow is turbulent.
A more satisfactory method of obtaining a uniform
coating is to cause the coating gas to flow substantially
parallel to the surface of a moving ribbon of glass to be
coated under laminar flow conditions as opposed to turbulent
flow conditions. A method and apparatus for achieving
laminar flow conditions is disclosed in U.S. Patent No.
4,469,045. The coating gas is directed onto a surface to be
coated by a distributor extending across the upper surface of
a moving ribbon of glass and across the direction of movement
of the ribbon. This device is especially useful for applying
a coating from a gas which reacts on contacting the hot glass
surface to deposit a coating material on the glass, such as a
metal vapor. The temperature of the gas supply and the
distributor is preferably kept sufficiently high to prevent
condensation of the coating gas, but sufficiently low to
prevent any substantial decomposition or other deleterious
reactions of the coating gas before the coating gas reaches
the glass surface.
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The precise temperature control required for proper
coating is difficult to obtain. Current systems attempt to
maintain the optimum temperature by cooling the distributor :
with high pressure steam, water, oil, or gas. Such systems
are complicated, expensive and often dangerous to operate.
SUMMARY OF THE INVENTION
The present invention concerns a method of and an
apparatus for coating flat glass utilizing a distributor beam
positioned above a moving ribbon of hot glass. Two or more
separate reactant gases are each directed to a separate
plenum formed in the interior of the beam which plenums are
divided by one or more septums. The gases are separated by
the septum as they flow from the plenums and through flow
distributing mechanisms such as separate waffle packs or
baffle stacks to insure a uniform distribution across the ;-
width of the glass ribbon. The temperature of the plenums
and thus of the gases in the plenums is controlled with water ;~
cooling and ~lectric heaters.
The gases exiting the flow distributing mechanisms enter
a channel or duct which extends the length of the distributor -~
beam and opens toward the upper surface of the glass ribbon.
Thorough mixing of the gases in the duct is achieved by a
unique finger baffle in single or multiple stages. The duct
25 is defined by blocks of material having relatively high :~
thermal conductivity which are insulated from the water
cooled plenums and include electric heaters with thermocouple
feedback. The plenums and the blocks are surrounded by and :
attached to a water jacket and support. The means for
fastening the plenums and the blocks to the water jacket and
support and the insulating material are selected to maintain
temperature compensating contact pressure and heat transfer ~:
rates respectively. The temperature of the blocks is
maintained at a desired level by controlled heat transfer to
the water cooled jacket and support around the plenum and by
the use of the electric heaters.
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STATEMENT OF THE INVENTION
In accordance with the present invention, there is provided an apparatus
for depositing a coating material on a surface of a glass sheet comprising: at least a
pair of plenums for receiving separate coating gases and each having an outlet; a mixing
chamber having an inlet connected to the plenum outlets and an outlet adapted to be
positioned adjacent a surface of a sheet of glass to be coated, t~le mixing chamber being
defined by spaced apart walls of blocks of material having a relatively high thermal
conductivity; a support defining a cooling fluid duct; insulating material positioned
between the plenums and the support and between the blocks and the support; and
cooled fastener means for attaching the plenums, the blocks and the insulating material
to the support including a threaded fastener extending through the blocks and the
insulating material and threadably engaging the support, a bushing extending between a
head of the threaded fastener and the support and through which the threaded fastener
extends, the threaded fastener having a relatively high coefficient of thermal
conductivity, and the bushing being formed of an insulating material.
BRIEF DESCRllYrlON OF THE DRAWINGS
In the accompanying drawings:
FIG. 1 is a side elevational view of a float glass manufacturing apparatus ~:
shown in cross-section and including a distributor beam in accordance with the present .
invention;
FIG. 2 is an enlarged side elevational cross-sectional view of the ;
distributor beam shown in FI~. 1;
FIG. 3 is an enlarged fragmentary view of one of the temperature
compensated fasteners shown in FIG. 2;
FIG. 4 is a block diagram of the control system for the distributor beam
shown in FIG. 1; and
FIG 5 is a side elevational cross-sectional view of an alternate
embodiment of the distributor beam shown in FIG. 1.
D~SCRlPTION OF THE PREFERRED EMBODlMENT
A distributor beam in accordance with the present invention can be utilized
in applying a uniform coating to the upper surface of a ribbon of float glass. The
position
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of the distributor beam with respect to the inlet snd outlet
ends of a bath upon which the ribbon floats depends upon the
optimum temperature of the glass in relation to the material
being deposited. The beam can also be utilized in the lehr
if the temperatures and the ambient atmosphere are suitable
for coating chemistry. In FIG. 1, molten glass 11 is
delivered in a conventional manner along a canal 12 leading
from the outlet of a glass melting furnace (not shown). The
canal 12 terminates in a spout having side jambs 13 and a lip ~-
14. The flow of the molten glass to the spout, usually soda-
lime-silica glass, is controlled by a regulating tweel 15.
The spout extends over an inlet end wall 16 of a tank
structure comprising a floor 17, an outlet end wall 18 and
sidewalls 19.
The tank structure contains a bath of molten metal 20,
usually molten tin or tin alloy in which tin predominates,
and molten glass flows at 21 over the spout lip 14 onto the
surface of the molten metal bath 20 at the inlet of the bath. -
The temperature at the inlet is maintained in the region of
one thousand degrees centigrade by heaters 22 mounted in a
roof structure 23 which is supported over the tank structure -~ .
and defines a head space 24 above the molten metal bath. The
roof structure has an inlet end wall 25 which depends
downwardly close to the surface of the molten bath 20 to
define an inlet 26 of restricted height. An extension 27 of
the roof structure 23 extends up to the tweel 15 to provide a
chamber in which the spout is enclosed.
The roof structure 23 also has a downwardly depending
wall 28 at the outlet end. An outlet 29 for a ribbon of
glass 30 produced on the bath is defined between the lower
face of the outlet end wall 28 of the roof structure and the
upper face of the outlet end wall 18 of the bath. Driven
traction rollers 31 are mounted beyond the outlet 29 with the
upper surfaces of the rollers just above the level of the
upper surface of the bath end wall 18 so that the ribbon of
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glass 30 is lifted gently from the bath surface for discharge
horizontally away from the outlet 29 on the rollers 31.
A protective atmosphere, for example, 95~ nitrogen and
5~ hydrogen, is maintained at a plenum in the head space 24
over the bath, being supplied through ducts 32 extending
downwardly through the roof 23 and connected to a common
header 33. Protective a~mosphere flows outwardly through the
~s inlet 26 to fill the chamber under the extension ~ enclosing
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the spout.
A temperature gradient is maintained down the bath from
the temperature of about one thousand degrees centigrade at
the inlet end of the bath to a temperature in the range of
about five hundred seventy degrees centigrade to six hundred
fifty degrees centigrade at the outlet end where the ribbon
of glass is discharged from the bath. At this lower
temperature at the outlet, the glass 30 is sufficiently
stiffened to be unharmed by its contact with the traction
rollers 31, but can still be lifted from the bath surface as
illustrated.
The molten glass 11, which flows over the spout lip 14
and onto the bath at 21, is permitted to flow laterally on
the bath to form a layer 34 of molten glass which is then
advanced as a ribbon which is cooled and discharged from the
bath. The width of the tank structure containing the bath
between the sidewalls 19 is greater than the width of the
ribbon.
A gas distributor beam 35 for supplying coating gas to
the surface of the glass ribbon is located transversely of
the path of travel of the ribbon of glass along the bath near
the outlet end of the bath as illustrated in FIG. 1. The
distributor thus extends across the upper surface of the
ribbon of glass and across the direction of movement of ~he
ribbon. The gas distributor beam 35 is illustrated in
greater detail in FIG. 2.
The gas distributor beam 35 includes an inverted
generally U-shaped channel member 36 having a substantially
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horizontal top wall 37, and downwardly depending side walls
38 and 39 facing the outlet end and the inlet end of the bath :
respectively. Within the channel member 36 is positioned
another inverted U-shaped channel member 40 having a ~
5 generally horizontally extending top wall 41, and downwardly ~ -
depending side walls 42 and 43 facing the outlet end and the ;~
inlet end of the bath respectively. The lower ends of the
side walls 39 and 43 are joined by a horizontal member 44
which can be attached by any convenient means such as
welding. The lower ends of the side walls 38 and 42 are
similarly attached to a horizontal member 45. Thus, the
channel member 36, the channel member 40, the horizontal
members 44 and 45, an end wall 46, and an opposite end wall
(not shown) form a support which defines a ~acket or duct for ~ -
the passage of heat transfer fluids such as water. Although
not shown, conventional inlet and outlet means can be
connected to the support for supplying the heat transfer
fluid at a lower temperature to the duct and removing the
heat transfer fluid at a higher teMperature from the duct.
Also, one or more partitions could be formed in the duct for
defining separate passages for the heat transfer fluid. For
example, a generally vertically extending wall could be
formed between the top wall 37 and the horizontal member 45
to divide the area between the side walls 38 and 42 into :
separate passages with the area closer to the side wall 42
being for inlet heat transfer fluid and the area closer to
the side wall 38 being for outlet heat transfer fluid flowing
in opposite directions.
The support defining the fluid duct is attached to a
pair of blocks formed of a relatively high thermal
conductivity material defining an outlet passage for the
coating gas to be directed toward the upper surface of the
layer of molten glass 34 floating on the surface of the
molten metal 20. For example, a lead-toe block 47 has a
generally vertically extending surface which faces the side
wall 43. An attachment block 48a is attached to the side
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wall 43 and a sheet of insulating material 49 is positioned
around the attachment block 48a between the side wall 43 and
the lead-toe block 47. The lead-toe block 47 can be attached
to the side wall 43 by a plurality of cooled fastener means.
For example, a threaded fastener 48b extends generally
horizontally through an aperture formed in the block 47 and
threadably engages a threaded aperture formed in the attached
block 48a. The fastener 48b can also extend through a
bushing 48c positioned in the aperture in the block 47 and a
washer 48d can be positioned under the head of the fastener
48b. Thus, the fastener 48b does not directly contact the
block 47. Of course, a plurality of such cooled fastener
means can be spaced apart between opposite ends of the block
47.
Similarly a center block 50 is attached along an upper
surface to the horizontal member 45 by a generally
horizontally extending attachment plate 51a and cooled
fastener means. The plate 51a is attached to the member 45
by any suitable means such as welding and a sheet of
insulating material 52 is positioned between the block 50 and
the attachment plate 51a. A pair of threaded fasteners 51b
extend through the block 50 and the insulating material 52
and threadably engage threaded apertures formed in the
attachment plate 51a. Each of the fasteners 51b can also
extend through a bushing 51c retained in the aperture in the
block 50 and a washer 51d can be positioned under the head of
the fastener 51b. A plurality of such cooled fastener means ~::
can be spaced apart between ends of the block 50.
A spacer plate 53 is attached to a downwardly facing
surface of the top wall 41. A sheet of insulating material
54 is attached to a downwardly facing surface of the spacer
plate 53 and a pair of attachment blocks 55 and 56 are
positioned adjacent a downwardly facing surface of the
insulating material 54. A pair of inverted U-shaped channel
members 57 form a pair of adjacent plenums 58. Each of the
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channel members 57 has a top wall attached to a downwardly
facing surface of one of the attachment blocks 55 and 56 and
downwardly extending side walls. The attachment blocks 55
and 56 and the inner side walls of the channel members are
separated by a downwardly extending septum 59 which has an
upper edge abutting the insulating material 54. The outer
i sidewalls of the channel members 57 abut~ associated side
.~. ` blockS60. Each of the side blocks 60 has an upper surface
which abuts the downwardly facing surface of a respective one
of the attachment blocks 55 and 56.
A pair of support plates 61 each ~ e an upwardly facing
recess 62 formed therein for retaining the lower edges of the
outer side walls of the channel members 57 and the lower
edges of the side blocks 60. The side blocks can be attached
to the support plates by threaded fasteners (not shown).
Each of the support plates 61 also has a downwardly extending
flange 63 which flanges abut the upper surfaces of the lead-
toe block 47 and the center block 50. Thus, the spacer plate
53, the insulating material 54, the attachment blocks 55 and
56, the U-shaped channels 57, the side blocks 60, and the
support plate 61 form a plenum structure which extends
between the downwardly facing surfaces of the top wall 41 and
the upwardly facing surfaces of the blocks 47 and 50 and is
positioned between the side walls 42 and 43. The plenum
structure i9 attached to the cooling jacket by cooled
fastener means. A pair of spacers 64a are positioned between
the top walls 37 and 41 to prevent mo~ement of the walls
toward one another when the fastener means are tightened. A
threaded fastener 64b extends through the top wall 37, one of
the spacers 64a, the top wall 41, the spacer plate 53, and
the insulating material 54 and threadably engages the
attachment block 55. The fastener 64b can also pass through
a bushing 64c which extends from the outer surface of the top
wall 37 to the insulating material 54. A washer 64d can be
provided under the head of the fastener 64b. A plurality of
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such cooled fastening means are provided spaced from end to
end of the beam 35.
A pair of waffle irons 65 are positioned between a
downwardly facing surface of each of the support plates 61
and an upwardly facing surface of the blocks 47 and 50.
- ~ Horizontally extending positioning ~ 66 are threadably
~ ~ engaged in the side surfaces of the waffle irons and each of
the positioning bolts 66 has a head abutting an inwardly
facing surface of a corresponding one of the flanges 63 which
flanges function as thrust plates. Thus, by rotating the
positioning bolts 66, the waffle irons 65 can be moved toward
or away from facing sides of the septum 59 which extends
between the waffle ir,ons 65 and into a mixing chamber 67
defined between the ~ block 47 and the central block
50. A pair of waffle packs 68 are positioned between the
septum 59 and each of the waffle irons 65. Typically, a one
half to one inch extension of the septum is necessary to
prevent clogging of the waffle packs.
The waffle packs 68 are representative of known types of
flow uniformizing means which define a plurali~y of channels
of small cross-sectional area relative to the cross-sectional
area of the plenums 58. Thus, when coating gas is supplied
under pressure to the plenums 58, the pressure drop along the
plenums is small compared to the pressure drop through the :~
restricted channels of the waffle packs 68. The waffle packs
effectively constitute gas flow restrictor means to insure
release of coating gas at a substantially constant pressure ~ ~-
and temperature along the whole of its length, and hence ::-~ ;
uniformly across the width of the glass to be coated. As
shown by the arrows, the gases supplied to the plenums 58 are
separated by the septum 59 and flow through associated ones
of the waffle packs 68 into the upper portion of the mixing
chamber 67.
The two separate gases from the plenums 58 enter the
upper portion of the mixing chamber 67 and contact a finger
bafile 69 which extends across the wldth of the mixing
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chamber 67. The finger baffle 69 includes two sets of
alternating angle fingers extending across the width of the
mixing chamber 67 and having opposite ends secured in the
blocks 47 and 50.
Gas flowing from either of the plenums 58 through the
associated waffle pack 68 first encounters one end of the
fingers closer to the plenum outlet. Half of the gas will
strike the fingers and be directed towards the opposite side
~ ~:of the mixing chamber 67. The~half of the gas will flow
10 between the fingers and strike the lower ends of the other :.
set of fingers. Thus, the two gas streams are split into
multiple streams and redirected to thoroughly mix the two
gases which mixture exits the bottom of the finger baffle 69
and flows into a distribution slot 70 defined between the
facing surfaces of the blocks 47 and 50.
The lead-toe block 47 extends below the lower surface of
the central block 50 and is shaped to redirect the vertically
downwardly flowing gas (arrows) to a horizontal laminar flow
between the lower surface of the central carbon block 50 and .
the upper surface of the sheet of molten glass 34. In FIG.
2, the sheet 34 is moving in the direction of the arrows and
tends to pull the gas along with it from the side of the
carbon block 50 defining the mixing chamber 67 and the
distribution slot 70 toward the opposite side to which there
25 is attached a means for collecting that portion of the gas ::
mixture which is not deposited on the surface of the sheet
34. The collection means can be an integral baffle stack
ex~ractor formed of high thermal conductivity blocks
surrounded and supported by a water cooled support supplied
with fluid in a manner similar to the previously described
support for the blocks 47 and 50.
A generally vert$cally extending attachment plate 71 is ~
attached to an exterior surface of the side wall 38. A :~ ::
generally vertically axtending sheet of insulating material
35 72 abuts an outer surface of the attachment plate 71 and has ~
a lower edge resting upon an upper surface of the insulating~ ~ :
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11
material 52. The center block 50 and the insulating material
52 extend beyond the side wall 38 toward the outlet end of
the bath to provide support for a lower edge of a generally
vertically extending side wall block 73. Spaced from the
5 side wall block 73 is a generally vertically extending second -~
side wall block 74 such that an extraction chamber 75 is : -
formed between the blocks 73 and 74. The extraction chamber
75 is open at the bottom for receiving the gas mixture which
ic not deposited on the surface of the sheet 34 and is closed
at its upper end by a generally horizontally extending top
wall block 76 resting on the upper ends of the side wall
block 73 and 74.
The upper end of the sheet of insulating material 72 ; : .
abuts one side of the top wall block 76 and another sheet of .
15 insulating material 77 abuts the other side of the top wall .;
block 76 and the outer side surface of the side wall block
74. A generally horizontally extending sheet of insulating
material 78 abuts the upper surface of the top wall block 76. -:-
A generally horizontally extending attachment plate 79
20 extends across the upper surface of the insulating material :~
78 and a generally vertically extending attachment plate 80
abuts the outer surface of the insulating material 77. A
water cooled support 81 has an inverted J-shape cross- ~ -
section. The support 81 is attached to the outer surfaces of
the attachment plates 79 and 80 by any suitable means. The
top wall block 76 is attached to the support 81 by suitable ::
fastener means which extend through the insulating material
78 and threadably engage the attachment plate 79. The side :
wall block 74 is attached to the support 81 by similar
fastener means which extend through the insulating material
77 and threadably engage the attachment plate 80. A :~
generally vertically extending sheet of insulating material
82 abuts a side surface of the top wall block 76 and is
retained against the block 76 by the support 81. A plurality
35 of generally horizontally extending baffles 83 are attached ::
to and extend outwardly from the side wall blocks 73 and 74
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1~ .
into the extraction chamber 75. The baffles typically extend
from alternate sides and are spaced progressively farther
apart from the bottom to the top of the chamber 75.
The cooled threaded fastener closest to the extraction
chamber 75 is shown in enlarged ~orm in FIG. 3. The aperture
extending through the center block 50 has an enlarged opening
51e for retaining a flanged end 51f of the bushing 51c. The
enlarged opening 51e is closed by a plug 51g as shown in FIG.
2. In a similar manner an enlarged opening 48e for the
threaded fastener 48b can be closed by a plug 48g having the
contours of the mixing chamber 67.
In order to maintain a proper temperature for depositing
the coating material on the surface of the sheet 34 and
minimizing undesirable deposits on the blocks 47 and 50, each ~
15 of the blocks 47 and 50 can be provided with a plurality of ~ -
heating means such as a heater 84 positioned in the block 47
and a heater 85 positioned in the block 50. The heater 84 is ;~
located in a recess 86 formed in the block 47 and is
connected to a power lead 87 which in turn is connected to
control apparatus (shown in FIG. 4) for supplying electrical
power to the heater. The control apparatus can be located
remotely from the beam and the lead 87 can extend through the
block 47 and through a wire duct 88 formed between the side
wall 43 and the side block 60 - support plate 61 structure.
Similarly, the heater 85 is located in a recess 89 formed in
the block 50 and is connected to a power lead 90 which in
turn is connected to the control apparatus. The lead 90 can
extend through the block 50 and through a wire duct 91 formed
between the side wall 42 and the side block 60 - support
plate 61 structure.
A thermocouple 92 can be positioned in a recess 93
formed in the block 47. The thermocouple 92 can be connected
to a signal lead 94 which in turn is connected to the control
apparatus shown in FIG. 4 through the wire duct 88. Thus,
the heater 84 can be controlled in accordance with the
temperature sensed by the thermocouple 92 to maintain a
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13 1332;~81
desired temperature in the block 47 adjacent the upper
surface of the strip of molten glass 34. Similarly, a
thermocouple 95 can be located in a recess formed in the
block 47 ad;acent the distribution slot 70 and a thermocouple
96 can be located in a recess formed in the block 47 ad;acent
the finger baffle 69. Thermocouples 97 and 98, corresponding . :
to the thermocouples 95 and 96 respectively, and a
thermocouple 99 ad~acent the inlet to the extraction chamber :
75 are located in recesses formed in the block 50. Thus, the
control apparatus can control the power supplied to the
heater 89 in accordar.ce to the temperature sensed by the :~.
thermocouples 97, 98 and 99 in order to maintain a desired . :
temperature between the carbon block 50 and the upper surface
of the sheet of molten glass 34.
The distributor beam 35 includes both cooling and
heating means for maintaining the optimum temperature for the -~
coating gases both in the plenums 58 and adjacent the surface : :~:
to be coated on the sheet of molten glass 34. As shown in
FIG. 4, the heater 84 is connected by the power lead 87 to a :.
20 heater control 100. The heater control 100 is a conventional ~ ~ :
unit which is connected to a source of electrical power (not ::
shown) by a line 101. The heater control 100 receives
signals on a signal line 102 connected to a temperature
controller such as a microprocessor 103 for controlling the
amount of electric power supplied to the heater 84 thereby
controlling the heat applied to the block 47. The
thermocouple 92 is connected by the lead 94 to an input of :
the microprocessor 103 to provide information about the ~.
temperature of the block 47. Although not shown, the
thermocouples 95 and 96 are connected in a similar manner to
the microprocessor 103. Furthermore, the heater 84 is
representative of one of a plurality of such heaters which
can be spaced from end to end of the block 47. Of course,
the heater 85 and the thermocouples 97, 98 and 99 in the
block 50 can be connected in a similar manner for controlling
the temperature of the block 50. The temperature controller :
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microprocessor 103 responds to the temperature signals generated by the thermocouples
and set point temperature signals inputted and stored to generate the control signals to
the heater controls.
As was previously stated, the cooling fluid for the water cooled supports
S flows into and out of the ducts formed in the supports. For example, a fluid line 104
can be connected between a source of cooling fluid (not shown) and a valve lOS.
Another fluid line 106 can be connected between the valve 105 and one of the supports.
The valve lOS can be any conventional type of valve such as a solenoid operated valve.
Thus, a source of electric power (not shown) is connected by a power line 107 to a
valve control 108. The valve control 108 receives control signals from the
microprocessor 103 on a signal line 109 and applies power to operate the valve 104 on
a line 110. The valve 105 and the valve control 108 are representative of elements
which could be used on both the inlet and the outlet of each support and a plurality of
such elements could be utilized where the supports are divided into multiple chambers.
lS The present invention maintains the optimum temperature by controlling
the heat transfer to the water cooled supports through the selection of suitable insulation ~;
and the maintenance of temperature compensating contact pressures between the blocks
and the supports. The compensating contact pressures are maintained by the threaded
fastening means. For example, the blocks 47 and S0 are typically formed of a graphite
20 reactor material having a thermal coefficient of expansion of approximately "1.3"~ The
threaded fasteners 48b and Slb can be formed of a material having a relatively high
coefficient of thermal conductivity. The bushings 48c and 51c can be formed of an
insulating material to resist heat transfer from the blocks 47 and S0 to the fasteners 48b
and 51b respectively. The fasteners 48b and 51b are cooled by drawing heat from them
25 through the attachment block 48a and ~he attachment plate Sla respectively and through
the side wall 43 and the member 45 respectively to the cooling fluid. Thus, the cooled
fasteners 48b and Slb tend not to expand and lengthen as the temperatures rise in the
blocks 47 and 50 respectively. However, the blocks 47 and 50 tend to expand between
the insulating materials 49 and 52 and the heads of the fasteners 48b and 51b,
30 respectively, thereby increasing the
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clamping pressure which increases the rate of heat transfer
from the blocks to water cooled supports thereby tending to
decrease the temperature of the blocks in a self-regulating
manner.
The beam 35 is designed to have an equilibrium
temperature at the critical surfaces facing the glass layer
34 of approximately fifty to two hundred degrees fahrenhei~
below the optimum temperature. The heaters 84 and 85 are
then utilized to bring the temperature of the critical
surfaces up to the optimum temperature. One advantage of the
present system is that it can utilize a conventional non-
pressurized water source with the water temperature between
freezing and boiling. Such a cooling source has the
advantages of being less hazardous to operating personnel and
does not cause pollution problems.
There is shown in FIG. 5 an alternate embodiment of the
gas distributor beam 35 of FIG. 2. A dual flow beam 135
includes a leading edge which is a mirror image of the
trailing edge. An inverted generally U-shaped channel member
136 having a substantially horizontal top wall 137 includes
downwardly depending side walls 138 and 139 facing the outlet
end and the inlet end of the bath respectively. Uithin the
channel member 136 is positioned another inverted U-shaped
member 140 having a generally horizontally extending top wall
141 and downwardly depending side walls 142 and 143 facing
the outlet end and the inlet end of the bath respectively.
The lower ends of the side walls 139 and 143 are joined by a
horizontal member 144 which can be attached by any convenient
means such as welding. The lower ends of the side walls 138
and 142 are similarly attached to a horizontal member 145.
Thus, the channel member 136, and the channel member 140, the ~:
horizontal member 144 and 145, and the end wall 146, and an
opposite end wall (not shown) form a support which defines a
symmetrical ~acket or duct for the passage of heat transfer
fluid such as water.
The support defining the fluid duct is attached to a
`~.: : , - , :: : : :
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.
pair of blocks formed of a relatively high thermal
conductivity material defining an outlet passage for the
coating gas to be directed toward the upper surface of the
layer of molten glass 34 floating on the surface of the
molten metal 20. For example, the lead-toe block 47 of FIG.
2 is replaced by a lead center block 147 which is a mirror
image of the center block 50 of FIG. 2. Similarly a trailing
center block 150 is similar to the center block 50 of FIG. 2.
The lead center block 147 is attached along an upper surface
to the horizontal member 144 by a generally horizontally
extending attachment plate 148a and cooled fastener means.
The plate 148a is attached to the member 144 by any suitable
means such as welding and a sheet of insulating material 149
is positioned between the block 147 and the attachment plate
148a. A pair of threaded fasteners 148b extend through the
block 147 and the insulating material 149 and threadably
engage threaded apertures formed in the attachment plate
148a. Each of the fasteners 148b can also extend through a
bushing 148c retained in the aperture in the block 147 and a
washer 148d can be positioned under the head of the fastener
148b. A plurality of such cooled fastener means can be
spaced apart between ends of the block 147.
Similarly the trailing center block 150 is attached
along an upper surface to the horizontal member 145 by a
generally horizontally extending attachment plate 151a and
cooled fastener means. The plate 151a is attached to the
member 145 by any suitable means such as welding and a sheet
of insulating material 152 is positioned between the block
15Q and the attachment plate 151a. A pair of threaded
fasteners 151b extend through the block 150 and the
insulating material 152 and threadably engage threaded
apertures formed in the attachment place 151a. Each of the
fasteners 151b can also extend through a bushing 151c
retained in the aperture in ~he block 150 and a washer 151d
can be positioned under the head of the fastener 151b. A
'` 1 33228 1 : ~
plurality of such cooled fastener means can be spaced apart ~-
between ends of the block 150.
A spaser plate 153 is attached ~o a downwardly facing
surface of the top wall 141 and a sheet of insulating
material 154 is attached to a downwsrdly facing surface of
the spacer plate 153. A pair of attachment blocks 155 and
156 are positioned ad~acent a downwardly facing surface of
the insulating material 154. A pair of inverted U-shaped
channel members 157 form a pair of ad~acent plenums 158.
Each o f the channel members 157 has a top wall, attached to a
downwardly facing surface of one of the attachment blocks 155
and 156, and downwardly extending side walls. The attachment
blocks 155 and 156 and the inner side walls of the channel
members 157 are separated by a downwardly extending septum
159 which has an upper edge abutting the insulating material
154. The outer side walls of the channel members 157 abut
associated side blocks 160. Each of side blocks 160 has an
upper surface which abuts the downwardly facing surface of a
respective one of the attachment blocks 155 and 156.
A pair of support plates 161 each have an upwardly
facing recess 162 formed therein for retaining the lower -
edges of the outer side walls of the channel members 157 and
the lower edges of the side blocks 160. The side blocks can
be attached to the support plates by threaded fasteners (not
shown). Each of the support plates 161 also has a downwardly
extending flange 163 which flanges abut the upper surfaces of
the lead center block 147 and the trailing center block 150.
A pair of spacers lS4a are positioned between the top walls -
137 and 141 to prevent movement of the walls toward one
another when the fastening means are tightened. A threaded
fastener 164b extends through the top wall 137, one of the
spacers 164a, the top wall 141, the spacer plate 153, and the
insulating material 154 and threadably engages the attachment
block 155. The fastener 164b can also pass through a bushing
164c which extends from the outer surface of the top wall 137
to the insulating material 154. A washer 164d can be
1 332281
18 ^
provided under the head of the fastener 164b. A plurality of
such cooled fastening means are provided spaced from end to
end of the beam 135.
A pair of waffle irons 165 are positioned between a
downwardly facing surface of each of the support plates 161
and an upwardly facing surface of the blocks 147 and 150.
Horizontally extending positioning bolts 166 are threadably
engaged in the side surfaces of the waffle irons and each of
the positioning bolts 166 has a head abutting an inwardly
facing surface of a corresponding one of the flanges 163
which flange is function as thrust plates. Thus, by rotating
the positioning bolts 166, the waffle irons 165 can be moved
toward or away from the facing sides of the septum 159 which
extends between the waffle irons 165 and into a mixing
chamber 167 defined between the blocks 147 and 150. A pair
of waffle packs 168 are positioned between the septum 159 and
each of the waffle irons 165. Typically, a one half to one
inch extension of the septum is necessary to prevent clogging
of the waffle packs. The two separate gases from the plenums
158 enter the upper portion of the mixing chamber 167 and
contact a finger baffle 169 which extends across the width of -
the mixing chamber 167. The two gas streams are thoroughly
mixed and the mixture exits the bottom of the finger baffle
lS9 and flow into a distribution slot 170 defined between the
25 facing surfaces of the blocks 147 and 150.
The distribution slot 170 opens to the upper surface of
a sheet of molten glass 34. The blocks 147 and 150 are
shaped to redirect the vertically downwardly flowing gas
(arrows) to a horizontal laminar flow between the lower
30 surfaces of the blocks 147 and 150 and the upper surface of
the sheet of molten glass 34. Adjacent the sides of the
blocks 147 and 150 opposite the distribution slot 170 are
means for collecting that portion of the gas mixture which is
not deposited on the surface of the sheet 34.
A generally vertically extending attachment plate 171 is
attached to an exterior surface of the side wall 138. A
:` 1 33228 1
19
generally vertically extending sheet of insulating material
172 abuts an outer surface of the attachment plate 171 and
has a lower edge resting upon an upper surface of the
insulating material 152. The trailing center block 150 and
the insulating material 152 extend beyond the side wall 138
toward the outlet end of the bath to provide support for a
lower edge of a generally vertically extending side wall
block 173. Spaced from the side wall block 173 is a
generally vertically extending second side wall block 174
such than an extraction chamber 175 is formed between the
blocks 173 and 174. The extraction chamber 175 is open at
the bottom for receiving the gas mixture which is not
deposited on the surface of the sheet 34 and is closed at its
upper end by a generally horizontally extending top wall
block 176 resting on the upper ends of the side wall blocks
173 and 174.
The upper end of the sheet of insulating material 172 .
abuts one side of the top wall block 176 and another sheet of ::
insulating material 177 abuts the other side of the top wall
20 block 176 and the outer side surface of the side wall block ;:
174. A generally horizontally extending sheet of insulating
material 178 abuts the upper surface of the top wall block
176. A generally horizontally extending attachment plate 179
extends across the upper surface of the insulating material
178 and a generally vertically extending attachment plate 180 ` :
abuts the outer surface of the insulating material 177. A
water cooled support 181 has an inverted J-shape cross-
section. The support 181 is attached to the outer surfaces
of the attachment plates 179 and 180 by any suitable means. :
The top wall block 176 is attached to the support 181 by
suitable fastener means which extend through the insulating
material 178 and threadably engaged the attachment plate 179.
The side wall block 174 is attached to the support 181 by
similar fastener means which extend through the insulating
material 177 and threadably engage the attachment plate 180.
A generally vertically extending sheet of insulating material
1 332281
182 abuts a side surface of the top wall block 176 and is
retained agalnst the block 176 by the support 181. A
plurality of generally horizontally extending baffles 183 are .
attached to and extend outwardly from the side wall blocks
173 and 174 into the extraction chamber 175. The baffles
typically extend from alternate sides and are spaced
progressively fsrther apart from the bottom to the top of the
chamber 175. A similar collection means is attached to the
beam 135 facing toward the inlet end of the bath. Such
collection means is identified by reference numerals 171'
through 183' corresponding to the elements identified by the
reference numerals 171 through 183 respectively. ~ :
In order to maintain a proper temperature for depositing
the coating material on the surface of the sheet 34 and
minimizing undesirable deposits on the blocks 147 and 150,
each of the blocks 147 and 150 can be provided with a
plurality of heating means such as heater 184 positioned in
the block 147 and a heater 185 positioned in the block 150.
In order to sense the temperatures in the blocks, a plurality
of thermocouples 192, 195 and 196 can be provided in the
block 147 and a similar plurality of thermocouples 197, 198
and 199 can be provided in the block 150. A control similar
to the control shown in FIG. 4 can be utilized with the
distributer beam 135.
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