Note: Descriptions are shown in the official language in which they were submitted.
MICROWAVE HEATING GLASS BENDING PROCESS
BACKGROUND OF THE INVENTION
Field of the Invention
[0001] This invention relates to a heating and bending (and/or shaping)
system using microwave focused beam heating, and more particularly, to a glass
line
having at least two, for example, at least three, heating furnaces. Wherein
the first
heating furnace is used to preheat one or more glass substrates to a first
temperature; the second heating furnace, being a glass forming furnace,
maintains
the substrates at the first temperature and heats and bends selected portions
of the
one or more glass substrates using microwave focused beam heating, and the
first
heating furnace, or a third furnace, controllably cools the one or more glass
substrates.
[0002] Also provided herein are methods for real-time monitoring of the
temperature and bending of a glass sheet to be shaped.
Description of the Related Art
[0003] Bending devices, commonly referred to in the bending art as
bending
irons or shaping irons, are well known in the art for shaping one or more
glass sheets
for use in the manufacture of monolithic and laminated transparencies for
land, water,
air and space vehicles. The method for shaping the glass substrates or sheets
for
use in the manufacture of transparencies for land and water vehicles usually
includes
providing one or more glass sheets having seamed or smoothed edges and a
predetermined size; moving the glass sheets supported on a bending iron
through a
furnace to heat soften the glass sheets; shaping the glass sheets;
controllably cooling
the shaped glass sheets to anneal or thermally temper the shaped glass sheets,
and
using the shaped glass sheets in the manufacture of a transparency for a land
or
water vehicle. The method for shaping glass substrates or sheets for use in
the
manufacture of transparencies for air and space vehicles usually includes
providing
one or more glass sheets having seamed or smoothed edges and a predetermined
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CA 2994524 2018-03-09
size; moving the glass sheets supported on a bending iron through a furnace to
heat
soften the glass sheets; shaping the glass sheets; controllably cooling the
shaped
glass sheets to anneal the shaped glass sheets; cutting the shaped glass
sheets to
a second predetermined size; seaming or smoothing the edges of the shaped
glass
sheets; chemically tempering the shaped glass sheets, or thermally tempering
the
shaped glass sheets, and using the tempered shaped glass sheets in the
manufacture of a transparency for an air or space vehicle.
[0004] The difference of interest in the present discussion between
shaping
glass sheets for use with transparencies for land and water vehicles and
shaping
glass sheets for use with transparencies for air and space vehicles is that
the glass
sheets for use with transparencies for land and water vehicles are cut to size
before
shaping or bending, whereas glass sheets for use with transparencies for air
and
space vehicles are cut to an over size before shaping and then cut to size
after
bending. For purposes of clarity, the process presently available for shaping
glass
sheets for use with transparencies for land and water vehicles is also
referred to as
"cut-to-size process", and the process presently available for shaping a glass
sheet
for use with transparencies in air and space vehicles is referred to as "cut-
after-bend
process".
[0005] The cut-to-size process allows cutting of the glass sheet to the
exact
size desired prior to the heating and bending of the glass sheet. However, the
cut-
to-size process does not account for any possible marring that may occur on
the
surface of the glass sheet, which can make the optical quality of the glass
sheet and
subsequently formed transparency unacceptable.
[0006] One solution to this problem is to provide a bending iron that
has
improvements in its design to prevent the marring of the surface of the glass
sheet
in contact with the bending iron. Such a bending iron is disclosed in USP
8,978,420.
Another solution to this problem is to reduce the temperature of the furnace
and/or
the time period of the heating cycle for shaping the glass sheets to reduce or
eliminate marring of the surface of the glass sheet in contact with the
bending iron
during the sheet shaping process.
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[0007] As can now be appreciated by those skilled in the art, it would
be
advantageous to provide a process of, and/or equipment for, shaping glass
sheets
for use in aircraft and space transparencies using the cut-to-size process,
while
eliminating or reducing marring of the surface of the glass sheet in contact
with the
bending iron.
[0008] It would also be advantageous, to eliminate the process of "cut-
after-
bend" by providing a system and method that allow for the efficient and
effective
heating, and/or shaping into complex shapes, and/or cooling of a sheet of
glass.
SUMMARY OF THE INVENTION
[0009] Provided herein are methods and systems for producing complex
glass
sheet shapes in an efficient, and automated manner. The methods and systems
provided herein are an improvement over previous technologies in that they
allow for
precise, tailor-made shapes, without the use of excessive heat and the
resulting
increase in the likelihood of marring. Further, by real-time feedback, the
methods
and systems described herein ensure that the complex shapes are achieved every
time.
[0010] Provided herein are methods and systems for shaping, and/or,
bending
a glass sheet comprising: preheating a glass sheet on a bending iron to a
preheating
temperature ranging from 600 F to 1000 F; increasing the temperature of the
sheet
to a temperature ranging from greater than the preheating temperature to less
than
a temperature at which the glass sags, for example in a temperature range of,
but
not limited to, 1100 F to 1250 F. Bending the glass sheet by: i.) selectively
heating
a portion of the glass sheet with a gyrotron beam controlled by a computer-
implemented protocol to a temperature at which at least a portion of the glass
sheet
sags; ii.) scanning at least a portion of the glass sheet with one or more
infrared (IR)
scanners at one or more time points during or after the selective heating step
and
obtaining from data obtained from the one or more IR scanners a temperature
distribution in at least two dimensions for at least a portion of the glass
sheet; iii.)
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comparing, using a computer-implemented process, the obtained temperature
distribution to a reference temperature distribution of the computer-
implemented
protocol; and selectively heating the glass sheet with the gyrotron beam
controlled
by a computer-implemented process to match the obtained temperature
distribution
with the reference temperature distribution of the computer-implemented
protocol.
[0011]
Additionally provided herein is a system comprising: a first furnace,
also herein referred to as the glass preheating chamber/oven, comprising
infrared
heaters and temperature sensors; a second furnace, also herein referred to as
the
glass shaping, glass bending, and/or glass forming furnace, comprising
infrared
heaters, a gyrotron system comprising a gyrotron device, or other device that
can
produce ultra-high frequency, e.g., at least 20 GHz (gigahertz), for example
ranging
from 20 GHz to 300 GHz, and high-power, e.g., at least 5 kW (kilowatt)
electromagnetic waves within the microwave spectrum, and an optical system for
controlling shape, location and movement of a beam of the gyrotron device to a
glass
sheet on a bending iron within the second furnace, and one or more infrared
(IR)
imaging sensors; a conveyor system for carrying a glass sheet on a bending
iron
through the first and second furnaces; a computer system connected to the one
or
more IR imaging sensors and the gyrotron system, comprising a processor and
instructions for controlling bending of a glass sheet in the second furnace by
selective
heating by the gyrotron system, the instructions comprising a computer-
implemented
protocol for heating and bending a glass sheet in the second furnace, where
the
computer system obtains a temperature profile of the glass sheet at one or
more time
points during the bending of the glass data from the one or more IR imaging
sensors,
compares the obtained temperature profile to a reference temperature
distribution of
the computer-implemented protocol, and controls the gyrotron beam system to
selectively heat the glass sheet to match the reference temperature
distribution. The
system optionally contains a third heating furnace to controllably cool the
glass sheet.
The third furnace comprising IR heaters, a forced cool air convection system,
and air
fans. If a third furnace is not present, then the first furnace will contain
all of these
features.
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[0012] In addition, this invention relates to a method of operating a
furnace
system to shape a glass sheet for, e.g., an aircraft transparency, the method
includes, among other things:
a) placing a flat glass sheet on a bending iron having a fixed shaping rail
and a shaping rail on an articulating arm defined as a moveable shaping rail;
b) positioning the bending iron having the glass sheet in an interior of a
furnace to heat the glass sheet to shape the glass sheet on the fixed shaping
rail while moving a beam of microwave energy from a gyrotron to heat portions
of the glass sheet overlaying the moveable shaping rail to shape the portions
of the glass sheet by movement of the articulating arm;
c) obtaining and transmitting to a computer one or more thermal images
of at least a portion of the glass sheet from one or more IR imaging sensors,
and optionally one or more shape profile images from one or more 3D imaging
sensors;
d) analyzing using a computer-implemented method the one or more
thermal images and optionally the one or more shape profile images, and
comparing the images with a computer-implemented method to one or more
reference thermal images, and optionally one or more reference shape profile
images, to determine a difference between the one or more thermal and,
optionally, shape profile images and the reference images;
e) based on a predetermined heat (power and speed) profile as
reference, directing, using a computer-implemented method, a beam of
microwave energy from the gyrotron, or other suitable source, to heat portions
of the glass sheet to match the one or more reference thermal images, and
optionally to match the one or more reference shape profile images, repeating
the analyzing and comparing steps until the one or more thermal images
match the one or more reference thermal images, and optionally until the one
or more shape profile images matches the one or more reference shape
profile images;
CA 2994524 2018-03-09
through the computer-implemented methods, producing a glass
viscosity distribution, allowing the glass sheet to be formed or bent into a
required shape with acceptable optical quality; and
g) controllably cooling the shaped glass sheet.
BRIEF SUMMARY OF THE DRAWINGS
[0013] Fig. 1 is a cross sectional view of a laminated aircraft
transparency
illustrating the laminated structure of the transparency.
[0014] Fig. 2 is a perspective view of shaped sheets that are shaped in
accordance to the teachings of the invention.
[0015] Fig. 3 is a perspective view of flat sheets that can be shaped in
accordance to the teachings of the invention to, among other things, provide
the
shaped sheets of Fig. 2.
[0016] Fig. 4 is perspective view of a non-limiting embodiment of a
bending
device that can be used in the practice of the invention to, among other
things, shape
glass sheets, e.g., but not limited to, the sheets of Fig. 3, to the shaped
sheets shown
in Fig. 2.
[0017] Fig. 5 is perspective view of a non-limiting embodiment of a
furnace
system that can be used in the practice of the invention to, among other
things, heat
and shape glass sheets, e.g., but not limited to, heating and shaping the
sheets of
Fig. 3 to the shaped sheets shown in Fig. 2 in accordance to the teachings of
the
invention.
[0018] Fig. 6 is an elevated cross sectional view of the furnace shown
in Fig.
5.
[0019] Fig. 7 is a perspective view of a furnace door having portions
removed
for purposes of clarity incorporating features of the invention to reduce heat
loss
between adjacent interiors of the furnace system shown in Figs. 5 and 6.
[0020] Fig. 8 is a perspective view of a carriage for supporting the
bending
iron, e.g., but not limited to, the bending iron shown in Fig, 4 and a
moveable
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conveyor section to move the carriage into the entrance end of the furnace
shown in
Figs. 5 and 6.
[0021] Fig. 9 illustrates a microprocessor for receiving signals from
sensors
and acting on the signals in accordance to the teachings of the invention.
[0022] Fig. 10 is a schematic partially in cross section showing a
gyrotron that
can be used in the practice of invention to heat selected portions of a glass
sheet.
[0023] Fig. 11 is a plan view showing the path of the microwave beam of
the
gyrotron to selectively heat portions of a stack of one or more glass sheets.
[0024] Fig. 12 is an elevated cross sectional side view of a furnace
system
incorporating features of the invention that can be used in the practice of
the invention
to, among other things, heat and shape glass sheets.
[0025] Fig. 13 is an elevated plan view of a furnace system
incorporating
features of the invention that can be used in the practice of the invention
to, among
other things, heat and shape glass sheets.
[0026] Fig. 14 is an elevated cross sectional view of a furnace of the
invention
that can be used in the practice of the invention to, among other things, heat
and
shape glass sheets.
[0027] Fig. 15 is an elevated cross sectional view of a furnace system
of the
invention.
[0028] Fig. 16 illustrates a flow diagram of a method of shaping a glass
sheet
in accordance with the invention.
DETAILED DESCRIPTION
[0029] As used herein, spatial or directional terms, such as "left",
"right",
"inner", "outer", "above", "below", and the like, relate to the invention as
it is shown
in the drawing figures. However, it is to be understood that the invention can
assume
various alternative orientations and, accordingly, such terms are not to be
considered
as limiting. Further, as used herein, all numbers expressing dimensions,
physical
characteristics, processing parameters, quantities of ingredients, reaction
conditions,
and the like, used in the specification and claims are to be understood as
being
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modified in all instances by the term "about". Accordingly, unless indicated
to the
contrary, the numerical values set forth in the following specification and
claims can
vary depending upon the desired properties sought to be obtained by the
present
invention. At the very least, and not as an attempt to limit the application
of the
doctrine of equivalents to the scope of the claims, each numerical value
should at
least be construed in light of the number of reported significant digits and
by applying
ordinary rounding techniques. Moreover, all ranges disclosed herein are to be
understood to encompass the beginning and ending range values and any and all
subranges subsumed therein. For ranges between (and inclusive of) the minimum
value of 1 and the maximum value of 10; that is, all subranges beginning with
a
minimum value of 1 or more and ending with a maximum value of 10 or less,
e.g., 1
to 3.3, 4.7 to 7.5, 5.5 to 10, and the like. Further, as used herein, the
term, "over"
means on but not necessarily in contact with the surface. For example, a first
substrate "over" a second substrate does not preclude the presence of one or
more
other substrates of the same or different composition located between the
first and
the second substrates.
[0030] Before discussing the invention, it is understood that the
invention is
not limited in its application to the specific illustrated examples as these
are merely
illustrative of the general inventive concept. Further, the terminology used
herein to
discuss the invention is for the purpose of description and is not of
limitation. Still
further, unless indicated otherwise in the following discussion, like numbers
refer to
like elements.
[0031] For purposes of the following discussion, the invention will be
discussed with reference to shaping a sheet for an aircraft transparency. With
regard
to the instant application, the term "glass shaping" refers to the concept of
glass
bending and/or glass forming. These terms are used interchangeably throughout
the
instant application. As will be appreciated, the invention is not limited to
the material
of the sheet, e.g. the sheet can be, but is not limited to, a glass sheet or a
plastic
sheet. In the broad practice of the invention, the sheet can be made of any
desired
material having any desired characteristics. For example, the sheet can be
opaque,
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transparent or translucent to visible light. By "opaque" is meant having
visible light
transmission of 0%. By "transparent" is meant having visible light
transmission in the
range of greater than 0% to 100%. By ''translucent" is meant allowing
electromagnetic energy (e.g., visible light) to pass through but diffusing
this energy
such that objects on the side opposite the viewer are not clearly visible. In
the
preferred practice of the invention, the sheet is a transparent glass sheet.
The glass
sheet can include conventional soda-lime-silica glass, borosilicate glass, or
lithia-
alumina-silica glass. The glass can be clear glass. By "clear glass" is meant
non-
tinted or non-colored glass. Alternatively, the glass can be tinted or
otherwise colored
glass. The glass can be annealed, heat-treated or chemically tempered. In the
practice of the invention, the glass can be conventional float glass, and can
be of any
composition having any optical properties, e.g., any value of visible
transmission,
ultraviolet transmission, infrared transmission, and/or total solar energy
transmission.
By "float glass" is meant glass formed by a conventional float process.
Examples of
float glass processes are disclosed in U.S. Patent Nos. 4,744,809 and
6,094,942.
[0032] In one example of the invention, the glass was a clear lithia-
alumina-
silica glass of the type disclosed in U.S. Patent No. 8,062,749, and in
another
example of the invention the glass was a clear soda-lime-silica glass of the
type
disclosed in U.S. Patent Nos. 4,192,689; 5,565,388, and 7,585,801.
[0033] The glass sheet can be used in the manufacture of shaped
monolithic
or shaped laminated transparencies for an aircraft. However as can be
appreciated,
the shaped glass sheets of the invention can be used in the manufacture of any
type
of transparency, such as but not limited to windshields, windows, rear lights,
sunroofs
and moon roofs; laminated or non-laminated residential and/or commercial
windows;
insulating glass units, and/or transparencies for land, air, space, above
water and
under water vehicles. Non-limiting examples of vehicle transparencies,
residential
and commercial transparencies, and aircraft transparencies and methods of
making
the same are found in U.S. Patent Nos. 4,820,902; 5,028,759, 6,301,858 and
8,155,816.
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[0034] Shown in Fig. 1 is a cross-sectional view of an exemplary
laminated
aircraft windshield 20 that has components that can be made by the practice of
the
invention. The windshield 20 includes a first glass sheet 22 secured to a
vinyl-
interlayer or sheet 28 by a first urethane interlayer 30, and the vinyl-
interlayer 28 is
secured to a heatable member 32 by a second urethane interlayer 34. An edge
member or moisture barrier 36 of the type used in the art, e.g., but not
limited to, a
silicone rubber or other flexible durable moisture resistant material, is
secured to (1)
a peripheral edge 38 of the windshield 20, i.e., the peripheral edge 38 of the
vinyl-
interlayer 28; of the first and second urethane interlayers 30, 34 and of the
heatable
member 32; (2) margins or marginal edges 40 of an outer surface 42 of the
windshield 20, i.e., the margins 40 of the outer surface 42 of the first glass
sheet 22
of the windshield 20, and (3) margins or marginal edges 44 of an outer surface
46 of
the windshield 20, i.e. margins of the outer surface 46 of the heatable member
32.
[0035] The first glass sheet 22, the vinyl-interlayer 28, and the first
urethane
interlayer 30 form the structural part, or inner segment, of the windshield
20. The
outer surface 42 of the windshield 20 faces the interior of the vehicle, e.g.
an aircraft
(not shown). The urethane layer 34 and the heatable member 32 form the non-
structural part, or outer segment, of the windshield 20. The surface 46 of the
windshield 20 faces the exterior of the aircraft. The heatable member 32
provides
heat to remove fog from, and/or to melt ice on, the outer surface 46 of the
windshield
20.
[0036] Shown in Fig. 2, are two pieces of shaped glass sheets 60 and 61
shaped in accordance to the teachings of the invention. Each of the glass
sheets 60
and 61 have curved end portions 62 and 64, and a shaped intermediate portion
66.
For example, the shaped glass sheets 60 and 61 can be shaped from flat glass
sheets 68 and 69 shown in Fig. 3 using the bending iron 70 shown in Fig. 4.
The
bending irons disclosed in U.S. Patent No. 8,978,420, entitled Bending Device
For
Shaping Glass For Use In Aircraft Transparencies (hereinafter referred to as
"USP
'420") can be used in the practice of the invention . For a detailed
discussion of the
bending iron 70, attention is directed to USP '420. Fig. 4 of this document
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corresponds to Fig. 4 of USP '420. As can be appreciated, the invention is not
limited
to the bending iron 70 and any design of a bending iron can be used in the
practice
of the invention to shape one sheet or simultaneously shape two sheets 68 and
69
(see Fig. 3), or shape more than two sheets to any desired shape.
[0037] Figs. 5 and 6 show an exemplary furnace 74, e.g., but not limited
to, a
furnace system, or apparatus of the invention for heating and shaping glass
sheets,
e.g., but not limited to, the shaped glass sheets 68 and 69. The furnace 74
includes
a first chamber 76 or furnace and a second chamber 78 or furnace. The first
chamber
76 preheats a glass sheet, e.g. but not limited to the flat glass sheet 68 or
flat glass
sheets 68 and 69 (see Fig. 3), supported or positioned on the bending iron 70
(Fig.
4), and controllably cools the shaped glass sheet, e.g. but not limited to the
shaped
glass sheet 60 or shaped glass sheets 60 and 61 (Fig. 2), supported or
positioned
on the bending iron 70 to anneal the shaped glass sheets. The second chamber
78
selectively heats portions of the flat glass sheets 68 and 69 in accordance to
the
teachings of the invention to shape the glass sheets 68 and 69 to a desired
shape,
e.g., but not limiting to the invention, to the shape of the shaped glass
sheets 60 and
61 shown in Fig. 2.
[0038] The first chamber 76 has a first opening 80 (also referred to as
the
"entrance 80" of the first chamber 76) and a second opening 82 (also referred
to as
the "exit 82" of the first chamber 76) opposite to and spaced from the first
opening
80 (second opening clearly shown in Fig. 6). The second chamber 78 has a first
opening 84 (also referred to as the "entrance 84" of the second chamber 78)
and a
second opening 86 (also referred to as the "exit 86" of the second chamber 78)
opposite to and spaced from the first opening 84 of the second chamber 78.
With
this arrangement, the flat sheets 68 and 69 supported on the bending iron 70
are
moved through the first opening 80 of the first chamber 76 into an interior 88
(see
Fig. 6) of the first chamber 76 to preheat the glass sheets 68 and 69. The
preheated
glass sheets 68 and 69 are moved through the second opening 82 of the first
chamber 76 and through the first opening 84 of the second chamber 78 into an
interior 90 (see Fig. 6) of the second chamber 78 to controllably heat the
glass sheets
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68 and 69 to shape the glass sheets in accordance to the teachings of the
invention.
The heated shaped glass sheets 60 and 61 are moved from the interior 90 of the
second chamber 78 through the first opening 84 of the second chamber 78 and
the
second opening 82 of the first chamber 76 into the interior 88 of the first
chamber 76
to controllably cool the shaped glass sheets. Thereafter, the shaped glass
sheets
60 and 61 are moved from the interior 88 of the first chamber 76 through the
first
opening 80 of the first chamber 76.
[0039] The interior 88 of the first chamber 76 and the interior 90 of
the second
chamber 78 are separated from one another and from the environment exterior of
the furnace 74 by providing a door 92 at the entrance 80 of the first chamber
76, a
door 94 at the entrance 84 of the second chamber 78, and a door 96 at the exit
86
of the second chamber 78. As can be appreciated, the invention is not limited
to the
type of doors 92, 94, 96 provided at the entrance 80, entrance 84, and exit
86,
respectively, and any door design and/or construction can be used in the
practice of
the invention. For example, the doors 92 and 96 can be similar in design and
construction. In view of the forgoing, the discussion is now directed to the
design
and construction of the door 92 with the understanding that the discussion,
unless
indicated otherwise, is directed to the door 96. With reference to Fig. 5, the
door 92
has sides 98 and 100 mounted in tracks 102 and 104 for reciprocal vertical
movement to move upwardly to open the entrance 80, and to move downwardly to
close the entrance 80, of the chamber 76, and for the door 96 to move upwardly
to
open the opening 86, and to move downwardly to close the opening 86. The
opening 86 of the furnace 78 is used for, among other things, making repairs
to, and
performing maintenance on, the furnace 78; cleaning out the interior 90 of the
furnace
78, e.g. but not limited to removing broken glass, and for expansion of the
furnace
74 discussed in detail below.
[0040] The doors 92 and 96 are moved along the reciprocating vertical
path
designated by double headed arrow 106 by a pulley arrangement 108 including a
pair wheels 110 and 112 spaced from one another and mounted on a rotating
shaft
114. Cables 116, 118 have one end 120 secured to top side 121 adjacent to the
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sides 98, 100 of the doors 92 and 96, respectively (clearly shown for door 92)
and
opposite ends 124 of the cables 116, 118, each connected to an air cylinder
126
(clearly shown for doors 92 and 96 in Fig. 5).
[0041] For example, the doors 92 and 94 can be each made of an outer
metal
housing 127 having one side 128 made of steel, and the opposite side 129
facing
the interior of its respective one of the furnaces made of stainless steel.
The interior
of the housing 127 can be filled with Kaowool insulation 130 (clearly shown in
Fig.
6).
[0042] The shaped glass sheets 60 and 61 are moved into the first
furnace
and annealed. The method of annealing glass sheets is well known in the art,
e.g.
see U.S. Patent 7,240,519, and no further discussion is deemed necessary.
After
the sheets are annealed, the door 92 is lifted and the shaped glass sheets are
removed from the first furnace 76. The temperature differential between the
first
furnace 76 and the second furnace 78 when the shaped glass sheets 60 and 61
are
removed from the first furnace 76 can reach temperatures in the range of 800-
1000 F. More particularly, the temperature of the first furnace 76 can be as
low as
200 F, the temperature the annealed shaped glass sheets 60 and 61 are removed
on the moveable conveyor 202 from the first furnace 76, whereas the
temperature of
the second furnace 78 can be greater than 1000 F, the glass preheat
temperature.
To reduce heat loss between the first and the second furnaces 76 and 78,
respectively, the door 94 can have a thermal conductivity of less than 0.80
BTU/(hr.ft. F).
[0043] With reference to Fig. 7, the exemplary door 94 includes a pipe
frame
94a having a stainless steel 11 gage sheet 94b secured to side 94c of the pipe
frame
94a and a stainless steel 11 gage sheet 94d secured to side 94e of the pipe
frame
94a. A layer 133 of insulating material sold under the registered trademark
Super
Firetemp M having a thickness of 1 1/2 inches was provided within the pipe
frame
94a between the stainless steel sheets 94b and 94d. A layer 94g of insulating
material is provided over the steel sheet 94d and covered with 0.008-0.010
inch thick
stainless steel foil 94h. The door 94 is mounted with the stainless steel
sheet 94h
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facing the interior of the furnace 78. Opening 94i and 94j are connected to a
compressor (not shown) to move room temperature compressed air through the
pipe
from 94a to cool the door 94 to prevent warping of the pipe frame 94a and
sheets
94b and 94d. Optionally, the peripheral edge of the layers 94g is covered by
the foil
94h.
[0044] The door 94 is connected to a vertically reciprocating inverted U
shaped member 136 (clearly shown in Fig. 5). More particularly, the door 94 is
connected to a middle leg 137 of the U-shaped member 136 by rods 138, and
outer
legs 139 and 140 are mounted for reciprocal vertical movement in vertical
tracks 141
and 142, respectively (see Fig. 5) in any convenient manner. The U-shaped
member
is moved vertically upwardly and downwardly by an electric motor 145 (shown
only
in Fig. 6). With the door 94 in the down position, the entrance 84 of the
furnace 78
is closed, and with the door 94 in the up position, the entrance 84 of the
furnace 78
is open. In the up position, as shown in Fig. 6, the door 94 is moved into an
envelope
146 formed on one side by a vertical extension 148 of a metal roof 150 of the
furnace
78 (see Fig. 6) and another side 152 of the envelope 146 is made of a ceramic
or
metal wall secured between the tracks 140 and 142 (see Fig. 5).
[0045] The design and construction of the first furnace 76 is not
limiting to the
invention and any type of furnace for heating or preheating a glass sheet to a
desired
temperature, e.g. a temperature below the softening, or sagging, temperature
of the
flat glass sheets 68 and 69 to avoid marring of the surface of the glass
sheets and
for controllably cooling the shaped glass sheet, e.g. but not limited to the
shaped
glass sheets 60 and 61 in the manner discussed below. More particularly, a
preheat
temperature in the range of 600-900 F is provided for a lithium-soda-lime
glass
sheet, and a preheat temperature in the range of 900-1025 F is provided for a
soda-
lime-silica glass sheet. The first furnace 76 can include a side wall 160 (see
Fig. 6)
and an opposite sidewall 162 (see Fig. 5), a top wall or ceiling 164, and a
bottom wall
166 to provide the interior 88 of the furnace 76. Stub rolls 168 extended
through the
sidewalls 160 and 162 into the interior 88 of the first furnace 76 for moving
a carriage
170 (see Fig. 8) into and out of the interior 88 of the first furnace 76, in a
manner
14
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discussed below. Infrared heaters 172 are provided on interior surface 174 of
the
sidewalls 160 and 162 (only sidewall 162 shown in Fig. 6), interior surface
176 of the
ceiling 164, and the bottom wall 166 to heat the interior 88 of the first
furnace 76 to
the desired temperature. Additionally, the first furnace comprises
thermocouples 191
to measure the heat of the furnace. Other devices, besides thermocouples, can
be
employed to measure temperature of the furnaces.
[0046] The design and construction of the second furnace 78 is not
limiting to
the invention and any type of furnace for heating a glass sheet to a desired
temperature, e.g. but not limiting to the invention, a heating temperature
above 900 F
for a lithium-soda-lime glass sheet, and a heating temperature above 1025 F
for a
soda-lime-silica glass sheet. Heat temperatures for glass sagging are
preferred, such
as in the range of 1100 F to 1250 F. For example, portions of the glass sheet
to be
shaped, e.g. but not limited to the shaped glass sheets 60 and 61 (see Fig. 2)
are
heated to their higher shaping temperatures using microwave energy generated
by
a gyrotron, or any other suitable microwave energy source. With reference to
Figs.
and 6, there is shown a device producing ultra-high frequency, high-power
electromagnetic waves 177, e.g., a gyrotron as shown, an optical box 178, and
a
mirror box 179 mounted on roof or ceiling 184 of the second furnace 78. The
operation of the gyrotron 177, optical box 178 and mirror box 179 are
discussed in
greater detail below.
[0047] The second furnace 78 is similar in construction to the first
furnace 76,
and includes a side wall 181 (see Fig. 6) and an opposite sidewall 182 (see
Fig. 5),
a top wall or ceiling 184, and a bottom wall 186 (see Fig. 6) to provide the
interior 90
of the furnace 78. The stub rolls 168 (see Fig. 6) extend through the
sidewalls 180
and 182 into the interior 90 of the second furnace 78 for moving the carriage
170
(see Fig. 8) into and out of the interior 90 of the second furnace 78, in a
manner
discussed below. The infrared heaters 172 can be provided on an interior
surface
188 of the sidewalls 180 and 182 (the sidewall 181 shown in Fig. 6 and the
sidewall
182 shown in Fig. 5), interior surface of the ceiling 184 and the bottom wall
186 to
heat the interior 90 of the second furnace 78 to a desired temperature. For a
lithium-
CA 2994524 2018-03-09
aluminum-silicate glass sheets, the interior 90 of the furnace 78 was heated
to a
temperature within the range of 600-900 F and for soda-lime-silicate glass
sheets,
the interior 90 of the furnace 78 was heated to a temperature within the range
of 900-
1000 F. Generally, but not limiting to the invention, the preheat temperature
of the
furnace 76 and the temperature of the furnace 78 with the gyrotron de-
energized are
similar such that the temperature attained by the glass sheets in the furnace
76 is
maintained in the furnace 78.
[0048] The temperature of the interiors 88 and 90 of the furnaces 76 and
78,
respectively was measured by thermocouples 191. The thermocouples 191 forward
a signal to a computer microprocessor system 193 (see Fig. 9). The computer
microprocessor system 193 acts on the signal to determine the temperature of
the
interiors 88 and 90 of the furnaces 76 and 78, respectively. If the
temperature of one
or both of the furnace interiors is (are) below a set temperature, a signal is
forwarded
along line 195 to increase the heat input of the furnace. On the other hand,
if the
temperature of one or both of the furnace interiors 88 and 90 is (are) too
high, a signal
is forwarded along the line 195 to decrease the heat input to the furnace. If
the
temperature of the furnace interior is in an acceptable range no action is
taken.
[0049] The conveyor system for the furnace 74 includes the stub conveyor
rolls 168 of the first furnace 76 driven by a gearing arrangement 192 (see
Fig. 5)
including a shaft for rotating the stub rolls and a motor to power the shaft
(the shaft
and motor of the gearing arrangement 192 are not shown), and includes the stub
conveyor rolls 168 of the second furnace 78 driven by a gearing arrangement
194
(see Fig. 5) including a shaft for rotating the stub rolls and a motor to
power the shaft,
the shaft and motor of the gearing arrangement 194 are not shown. As is
appreciated
by those skilled in the art, conveyors using stub rolls are well known in the
art and no
further discussion is deemed necessary.
[0050] With reference to Figs, 3-8, as needed, at a loading station (not
shown)
one or more glass sheets are positioned on a bending iron, e.g. the bending
iron 70
shown in Fig. 4. Two glass sheets, e.g. the glass sheets 68 and 69 (see Fig.
3), are
positioned on the bending iron 70, optionally ceramic dust (not shown) can be
used
16
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to prevent sticking of the shaped glass sheets 60 and 61. The bending iron 70,
having the sheets 68 and 69, is positioned on the carriage 170 (Fig. 8) and
the
carriage 170 is placed on stub rolls 200 of a moveable conveyor 202. The
moveable
conveyor 202 is moved from the loading area to the furnace area. The door 92
of the
first furnace 76 is opened (see Figs. 5 and 6) and the moveable conveyor 202
is
moved into the opening 80 to align the stub rolls 200 of the moveable conveyor
202
with the stub rolls 168 of the first furnace 76. The carriage 170 is then
moved into
engagement with adjacent stub rolls 168 of the first furnace 76, and the
carriage 170
is moved into the interior 88 of the furnace 76 by the stub rolls 168 of the
first furnace
76. The rotation of the stub rolls 168 is stopped when the carriage 170 is in
the
predetermined position in the interior 88 of the first furnace 76, which is
usually the
hottest position in the first furnace 76. After the rotation of the stub rolls
168 stops,
the carriage 170 having the bending iron 70 and the glass sheets 68 and 69
remains
in the first furnace 76 until the glass sheets 68 and 69 reach the desired
temperature,
e.g. the temperature for a lithium-aluminum-silicate glass is within the range
of
600-900 F, and the temperature for a soda-lime-silica glass is within the
range of
900-1000 F. Optionally, the carriage 170 can be moved slightly upstream and
downstream along the conveyor movement path to circulate the heated air in the
furnace around the sheets 68 and 69.
[0051] The
temperature of the glass sheets can be monitored in any
convenient manner, e.g., the temperature of the glass sheets 68 and 69 are
monitored by a an optical pyrometer, or an optical thermal scanner, such as
optical
pyrometer or optical thermal scanner manufactured by Land Instruments
International of Dronfield, UK (Land). A pyrometer or thermal scanner 204 is
mounted on the roof 164 of the first furnace 76 (see Fig. 5). More
particularly, a
pyrometer or thermal scanner 204, e.g. but not limited to an optical thermal
scanner
(made by Land), measures the temperature of the glass as the carriage 170
moves
toward the door 94 separating the furnaces 76 and 78. A signal is forwarded
along
line 204a to the computer microprocessor system 193 (see Fig. 9). If the
temperature
of the glass is within an acceptable preheat temperature range, e.g., at a
temperature
17
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just below the temperature at which the glass sags, the carriage 170 is moved
into
the furnace 78. If the glass is not within the acceptable shaping temperature
range,
the carriage 170 is not moved into the shaping furnace 78 and appropriate
action,
e.g., but not limited to, increasing the temperature of the furnace 76 if the
glass
temperature is too low or decreasing the temperature of the furnace 76 if the
glass
temperature is too high, is taken.
[0052] After the glass sheets 68 and 69 reach the desired temperature,
the
door 94 of the second furnace 78 is opened, and the stub rolls 168 of the
first furnace
76 and the second furnace 78 are energized to move the carriage 170 through
the
opening 84 of the second furnace 78 to a designated shaping position in the
interior
90 of the second furnace 78, to be discussed in detail below. The door 94 of
the
second furnace 78 can be closed at any time after the carriage 170 has passed
into
the interior of the second furnace 78. After the carriage 170 having the glass
sheets
68 and 69 and the bending iron 70 is positioned in the designated shaping
position
in the interior 88 of the second furnace 78, or the carriage 170 has cleared
the door
94 as discussed below, the door 94 is closed, and the shaping process of the
invention using the gyrotron 177 discussed in detail below is practiced.
[0053] After the glass sheets 68 and 69 are shaped, the gyrotron 177 is
de-
energized or deactivated, and the door 94 of the second furnace 78 is opened.
The
stub rolls 168 of the first and the second furnaces 76 and 78, respectively,
are
energized to move the carriage 170 having the shaped sheet 60 and 61 from the
interior 90 of the second furnace, through the opening 84 of the second
furnace 78
and into the interior 88 of the first furnace 74. After the carriage 170 is
moved into
the interior 88 of the first furnace 76, the door 94 of the second furnace 78
is closed.
The shaped glass sheets are controllably cooled to anneal the sheets. When the
annealing process is completed, the door 92 of the first furnace 76 is opened
and the
moveable conveyor 202 (see Fig. 8) is moved into the opening 80 of the first
furnace
76 into alignment with the stub rolls 168 of the first furnace 76. The stub
rolls 168 of
the first furnace are energized to move the carriage 170 out of the interior
88 of the
first furnace 76 onto the moveable conveyor 202. The moveable conveyor having
18
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the carriage 170 is moved to an unload station (not shown) and the shaped
glass
sheets are removed from the bending iron 70 in any usual manner.
[0054] The discussion is now directed to using the gyrotron 177 (see
Figs. 5,
6 and 10 as needed) to heat portions of one or more glass sheets to their
bending or
shaping temperature. Of note, the present application describes the use of a
gyrotron system. The gyrotron is a non-limiting example and any suitable
system
that might be employed to spot-heat a glass sheet through a thickness of the
sheet,
including exterior surfaces and the interior of the sheet. Suitable systems
include
systems that produce ultra-high frequency, e.g., at least 20 GHz (gigahertz),
and
high-power, e.g., at least 5 kW (kilowatt) electromagnetic waves within the
microwave spectrum. For example, such as a klystron or a traveling wave tube,
though the output frequency and wattage of these devices are less than that of
a
gyrotron system. As previously discussed, glass for aircraft transparencies
are made
using the cut-after-bend process to remove portions of the glass sheets having
optical distortions, e.g. but not limiting thereto resulting from long periods
of time
required for the glass sheets to rest on the bending iron to attain the
desired
temperature for bending. For example, it is expected that the overheating of
the
surface of the glass sheet using traditional methods, in order to achieve a
desired
bending of the glass, is rendered unnecessary by use of the gyrotron or other
source
of high-energy electromagnetic radiation. Glass sheet surface temperature can
be
reduced by 30-40% using a gyrotron to internally heat selected portions of the
glass
sheets to their bending or shaping temperature. As can now be appreciated, it
is
expected that the reduction of the need to overheat the glass surface by
traditional
methods of regulating furnace temperature, and the resultant elimination of
overheating of the bending irons and/or shaping rails on which the glass sheet
sits,
significantly reduces glass marring, and greatly facilitates bending of glass
sheets
for, e.g., aircraft transparencies using the cut-to-size process instead of
the cut-after-
bend process.
[0055] A gyrotron is a high-powered linear beam vacuum tube capable of
generating high-power, high-frequency electromagnetic radiation approaching
the
19
CA 2994524 2018-03-09
edge of the infrared terahertz (THz) spectrum. Its operation is based on the
stimulated cyclotron radiation of electrons oscillating in a strong magnetic
field, e.g.
as provided by a superconducting magnet. Any suitable microwave generator
capable of generating high-power, high-frequency electromagnetic waves, such
as
a microwave generator having an output frequency ranging from 20GHz to 300GHz,
and having a power output of at least 5 kW, would be suitable. A schematic,
indicating
the various parts of the gyrotron 177 is shown in Fig. 10. In general and not
limiting
to the invention, in the operation of the gyrotron 177, electrons that are
emitted by a
cathode 206 surrounded by gun coil magnets 208, are accelerated in a strong
magnetic field of a superconducting magnet 210. While an electron beam 212
travels
through the intense magnetic field of magnet 210, the electrons start to
gyrate at a
specific frequency given by the strength of the magnetic field. In a cavity
214, located
at the position with the highest magnetic field strength, the THz radiation is
strongly
amplified. Mode converter 216 is used to form free-gaussian beams 217 that
leave
the gyrotron 177 through a window 222 and is coupled to a waveguide 224. The
operation of gyrotrons is well known in the art and no further discussion is
deemed
necessary. Gyrotrons are commercially available from, e.g., Gyrotron
Technology,
Inc. of Philadelphia, Pennsylvania.
[0056] With
continued reference to Fig. 10, the free-gaussian beams 217 pass
through the waveguide 224 to the optical box 178. The optical box 178 has
mirrors
(not shown) arranged as is known in the art to collimate the free-gaussian
beams
217 into a single beam 225 and control the size, e.g. the diameter, of the
beam 225.
The collimated beam 225 leaves the optical box 178 through waveguide 226 and
passes into the mirror box 179. The mirror box 179 has one or more moveable
mirrors 228 (one mirror shown in phantom in Fig. 10) to move the beam 225
through
a predetermined area defined by a cone 230 (see Figs. 6 and 10). In Fig. 10,
the
beams 225 moving through the cone 230 are incident on the flat glass sheet,
e.g. the
flat glass sheets 68 and 69 positioned on a bending iron, e.g. the bending
iron 70
(Fig. 4). The sheets 68 and 69 and the bending iron 70 are shown in block
diagram
in Fig. 10.
CA 2994524 2018-03-09
[0057] The discussion is now directed to using the beam 225 from the
gyrotron
177 to heat portions 232 of the flat glass sheets 68 and 69 (see Fig. 3) that
are
shaped by an articulating arm 234 of the bending iron 70 (Fig. 4) and portions
236
shaped by the fixed shaping rail 238 of the bending iron 70. In general, the
flat glass
sheets 68 and 69 positioned on the shaping rail 239 of the articulating arm
234
maintain the articulating arm 234 in a down position as viewed in Fig. 4,
which
maintains weight 240 in the up position. As the portion 232 of the glass
sheets 68
and 69 overlaying the shaping rail 239 of the articulating arm 234 of the
bending iron
70 is heated to the shaping temperature of the glass sheets 68 and 69, the
weight
240 moves downwardly, moving the articulating arm 234 upwardly to shape the
portion 232 of the glass sheet 68 and 69 to the shape 232 shown on the sheets
60
and 61 in Fig. 2. For a more detailed discussion of the operation of the
articulating
arm 234 of the bending iron 70, reference should be made to USP '420. The
portions
236 of the flat glass sheets 68 and 69 are shaped by the fixed shaping rails
238 to
the portions 236 of the shaped glass sheets 60 and 61. In the practice of the
invention, the portions 232 and 236 of the glass sheets 62 are heated by the
beams
225 from the gyrotron 177 to quickly reach the bending temperature in the
range of
1000 to 1100 F for lithium-aluminum-silicate glass and in the range of 1100
to
1200 F for soda-lime-silicate-glass.
[0058] The microprocessor or computer system 193 (Fig. 9) is programmed
e.g., but not limited to a signal sent along wire 239, to control the
operation of the
mirrors of the optical box 178 to set the size of the beam 225 incident on the
portions
of the glass sheets being shaped, the movement of the mirror 228 of the mirror
box
179 to control the direction of movement and speed of movement of the beam 225
in the zone 230 (se Fig. 10), and the energy of the beam 225 by altering the
anode
voltage, strength of the magnetic field and/or the voltage applied to the
system of the
gyrotron. With reference to Figs. 9 and 10 as needed, the mirror 228 operated
by the
microprocessor 193 moves the beam 225 along a predetermined path 244 on
surface 246 of the top glass sheet, e.g. top glass sheet 68 facing the mirror
box 179.
The energy beam 225 as it moves along the path 244 in the area of the sheets
21
CA 2994524 2018-03-09
designated by the number 236, heats the glass sheets to their softening
temperature
for the glass sheets to take the shape of the fixed shaping rail 238 (see Fig.
4). The
energy beam 225 as it moves along the path 244 in the area of the sheets
designated
by the number 232 (see Fig. 11) heats the glass sheets to their shaping
temperature,
at which time the articulating arm 234 of the bending iron 70 shapes the
sheets in
the area 232. Mounted through the roof 180 of the furnace 78 on each side of
the
mirror box 177 are pyrometers 250 (see Fig. 6) to monitor the temperature of
the
glass. The pyrometers 250 are connected to the microprocessor or computer 193
by wires 251 to send a signal to the microprocessor 193, and the
microprocessor
forwards a signal along the wire 239 to maintain the temperature of the
selected
portions of the glass within a desired temperature range by altering the speed
of the
beam 225 along the path 244 and/or by altering the energy of the beam as
discussed
above. More particularly, decreasing the speed of the beam 225 increases the
temperature of the glass and vice versa, and increasing the anode voltage, the
magnetic field, and/or the applied voltage, increases the temperature of the
glass
and vice versa.
[0059] The following is an example of the invention to shape a glass
sheet for
use in the manufacture of an aircraft transparency. The flat glass sheets 68
and 69
(Fig. 3) are positioned on the bending iron 70 (Fig. 4). The bending iron 70
is placed
in the carriage 170 (Fig. 7) and the carriage is placed on the stub rolls 200
of the
conveyor 202. The carriage 170 having the bending iron 70 and glass sheets 68
and
69 is moved into the interior 88 of the first furnace 76 (Fig. 6) by the stub
rolls 168 of
the first furnace 76. The glass sheets in the closed interior of the first
furnace 76 are
heated to a temperature below the softening point temperature of the glass.
Thereafter, the carriage 170 having the heated glass sheets 68 and 69 is moved
by
the stub rolls 168 of the first furnace 76 and the second furnace 78 into the
interior
90 of the second furnace 78 and positioned within the area of the cone 230
(see Figs
6 and 10).
[0060] The temperature of the interior 90 of the second furnace 78 is
generally
the same temperature as the interior 88 of the first furnace 76, i.e. a
temperature
22
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below the shaping temperature of the glass sheets on the bending iron 70. At
this
temperature, the glass sheets positioned on the bending iron have not been
shaped.
After the carriage 170 positions the sheet within the cone 230, the gyrotron
177, the
optical box 178, and the mirror box 179, are energized to move the beam 225
along
the scan path 244 (see Fig. 10). As the beam 225 moves along the scan path
244,
the gyrotron 177 is in a work mode. The energy beam 225 as it moves along the
path
244 in the area of the sheets designated by the number 236, heats the glass
sheets
to their softening temperature for the glass sheets to take the shape of the
fixed
shaping rail 238 (see Fig. 4). The energy beam 225 as it moves along the path
244
in the area of the sheets designated by the number 232 (see Fig. 9) heats the
glass
sheets to their shaping temperature, at which time the articulating arm 234 of
the
bending iron 70 shapes the sheets in the area 232. As the beam moves along the
segments 250 of the scan path, the beam is in the work mode to heat the
segment
232 of the sheet 68. As the segment or portion 232 of the sheet 68 is heated
the
sheet segment softens and the weight 240 of the bending iron moves the
articulating
rail 238 upwardly to shape the portion 232 of the sheet 268. After the sheets
are
shaped, power to the gyrotron 177 is reduced or disconnected to put the
gyrotron
and beam 225 in the idle mode.
[0061] The stub rolls 168 of the second and first furnaces 78 and 76,
respectively, move the carriage 170 having the shaped sheets 60 and 61 from
the
interior 90 of the second furnace 78 into the interior 88 of the first furnace
76. The
shaped sheets in the first furnace 76 are controllably cooled to anneal the
shaped
glass sheets. Thereafter the carriage 170 is moved by the stub rolls 168 of
the first
furnace 76 onto the moveable conveyor 202, and the moveable conveyor moved to
an unload area (not shown).
[0062] As can now be appreciated, care is exercised to make certain the
carriage 170 (see Fig. 9) is moved into the furnaces 76 and 78, and between
the
furnaces 76 and 78, when the doors 92 and 94 (see Figs. 5 and 6) are open. As
a
safety feature, tracking sensors 300, 302 and 304 were used to track the
position of
the carriage 170 as it moved through the furnaces 76 and 78. Although not
limiting
23
CA 2994524 2018-03-09
to the invention, each of the tracking sensors 300, 302 and 304 included a
generated
continuous light beam, e.g., but not limited to, a laser generated beam of
light incident
on a detector. When the carriage 170 moved through the continuous light beam,
the
beam was directed away from the detector and the detector sends a signal along
a
cable 306 to the microprocessor 193 indicating that the light beam was not
incident
on the detector. The computer microprocessor system 193 sends a signal along a
wire 308 to open or close the door 92 or the door 94. By way of illustration
and not
limiting to the invention, the tracking detector 300 is positioned in the
furnace 76
spaced from the door 92 a distance greater than the width of the carriage 170.
The
travel of the beam of light is transverse to the path of travel of the
carriage 170. As
the carriage 170 moves into the furnace 76, the carriage 170 interrupts the
light beam
by directing the beam away from the detector of the sensor 300. The detector
of the
tracking sensor 300 sends a signal along the cable 306 to the microprocessor
193
indicating that the light beam is not impinging on the detector and the
microprocessor
sends a signal along cable 308 to energize the motor 124 (see Fig. 5) to close
the
door 92.
[0063]
Optionally, the glass sheets 68 and 69 are heated as the carriage 170
moves through the furnace 76, or the glass sheets 68 and 69 are moved to the
center
of the furnace and stopped to heat the sheets. After the glass sheets are
heated, the
glass sheets 68 and 69 (see Fig. 3) and the carriage 170 are moved toward the
door
94 separating the furnaces 76 and 78. The carriage interrupts the light beam
of the
sensor 302 and a signal is forwarded along the cable 308 to computer
microprocessor system 193 to energize the motor 145 to raise the door 94. The
system is timed such that the carriage 170 can continuously move from the
first
furnace 76 into the second furnace 78 without any interruptions. The carriage
170
moves into the furnace 78 and after completely entering the furnace 78
interrupts the
light beam of the sensor 304. The sensor 304 forwards a signal along cable 308
to
the microprocessor 193 to close the door 94; the microprocessor 193 forwards a
signal along the cable 308 to energize the motor to close the door 94. The
carriage
170 is moved into the shaping position and the conveyor stops. As can be
24
CA 2994524 2018-03-09
appreciated the distance from the shaping position to the beam of light of the
detector
304, and the speed of the carriage 170 are known, and in this fashion the
motion of
the conveyor can be stopped when the carriage and the glass sheets are in the
shaping position. In another example of the invention, a tracking sensor 309
(shown
in phantom and only shown in Fig. 6) is used to position the carriage 170 in
the
shaping position. As the carriage 170 displaces or interrupts the light beam
of the
tracking sensor 309, a signal is forwarded, e.g. along the cable 306 to the
computer
microprocessor system 193 and the computer microprocessor system forwards a
signal, e.g. along the cable 308 to stop the rotation of stud rolls to
position the
carriage 170 and the glass sheets in the shaping position. Optionally, the
sensor
309 and the timing of the computer microprocessor system can be used for
positioning the carriage relative to the beams.
[0064] After the glass sheets 68 and 69 are shaped, the carriage 170 and
the
shaped sheets are moved out of the furnace 74. More particularly and not
limiting to
the invention, the carriage 170 deflecting or interrupting the light beam of
the sensor
304 opens the door 94, interrupting the light beam of the detector 302 closes
the
door 94, and interrupting the light beam of the detector 300 opens the door
92.
[0065] As can be appreciated, the invention is not limited to the design
of the
furnace 74, and the invention contemplates practicing the invention with any
type of
furnace such as, but not limited to the furnaces shown in Figs. 5 and 6
discussed
above, and Figs. 12 - 15 discussed below. More particularly, shown in Fig. 12
is a
furnace 258 having the first and second furnaces 76 and 78, respectively,
discussed
above and a furnace 260 attached to the second opening 86 of the second
furnace
78 (see Figs. 5, 6 and 12). The furnace 260 is similar, if not identical, to
the first
furnace 76. With the furnace arrangement shown in Fig. 12, the carriage 170
having
the bending iron 70 having the sheets 68 and 69 can move along the path
designated
by the arrow 270 through the furnace 76 to preheat the glass sheets 68 and 69,
through the furnace 78 to shape the glass sheet 68, and through the furnace
260 to
anneal the shaped glass sheets 60 and 61 as discussed above for the first
furnace
76. In a second example of the invention, the furnace 258 can shape the glass
CA 2994524 2018-03-09
sheets 68 and 69 using the first and second furnaces 76 and 78, respectively,
as
discussed above by moving the carriage 170 having the bending iron 70 and the
glass sheets 68 and 69 along a reciprocating path designated by the arrow 272
and
shaping second group of glass sheets 68 and 69 using the furnaces 78 and 260
in a
similar manner as the furnaces 76 and 78, and moving the second group of glass
sheets along a reciprocating path designated by the arrow 274.
[0066] With reference to Fig. 13, there is shown another example of a
furnace
designated by the number 261. The furnace 261 includes the furnaces 76, 78 and
260 (see Fig. 12) and furnaces 262 and 264. The shaping furnace 78 is between
the
furnaces 262 and 264. The glass processed using the furnace 261 has paths of
travel 270 and 278 in the horizontal direction and paths of travel 270a and
278a in
the vertical direction, as viewed in Fig. 13; the reciprocal paths of travel
272 and 274,
and reciprocal paths of travel 275 and 276 in the vertical direction as viewed
in Fig.
13. The glass sheets moving along the path of travel 276 can move into and out
of
the furnaces 262 and 78, and the furnaces 264 and 78. As can be appreciated,
the
conveying system for the furnace 78 shown in Fig. 13 is adjustable or provided
with
a two tier conveying system to move the carriage along the path 278 through
the
furnaces 262, 78 and 262, and to move the carriage along the path 278a through
the
furnaces 76, 78 and 260.
[0067] With reference to Fig. 14, there is shown still another non-
limiting
embodiment of a furnace of the invention designated by the number 280. The
furnace 280 includes a first tunnel furnace 282 to preheat the flat glass
sheets 68
and 69 as they move in the direction of the arrow 284. The glass sheets 68 and
69
can be positioned on the bending iron 70, or as discussed above, the bending
iron
70 can be positioned in the carriage 170. Shaping furnace 286 positioned at
exit end
287 of the tunnel furnace 282 can have any number of gyrotrons to provide any
number of shaping zones, e.g. one shaping zone 230 shown in solid line, or two
shaping zones 231 shown in phantom, or three shaping zones shown in solid line
230 and phantom 231. A second tunnel furnace 288 is connected to exit end 289
26
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of the shaping furnace 286 to controllably cool the shaped glass sheets 60 and
61.
Additionally depicted are thermal sensor 324 and positional sensors 320 and
321.
[0068] Thermal sensor 324 is any sensor or scanning device, such as an
IR
scanner or IR imaging sensor, able to produce data representing the
temperature of
one or more portions of a glass sheet, such as a charged-coupled device (CCD),
an
infrared laser-light sensor device, a thermal imaging device or a thermal
scanner, as
are broadly known and commercially available. Representations of a glass sheet
can be produced by a computer implemented process, by assembling data, such as
raw CCD data, obtained from the thermal sensor, and producing a two-
dimensional
or three-dimensional temperature profile of at least a portion of the glass
sheet. As
indicated below, the thermal data obtained from the thermal sensor, and the
temperature profile produced from that data is compared to a reference
temperature
profile in a computer-implemented process, and any differences between the
produced temperature profile and the reference temperature profile are
triggers
selective heating of the glass sheet by the gyrotron to match the temperature
profile
of the glass sheet with that of the reference temperature profile. Computer-
implemented processes to perform these tasks, as well as any task indicated
herein
are readily devised and implemented by those of ordinary skill in the computer
imaging and process control arts. One or more thermal sensors can be used, and
more than one different type of sensor may be employed to obtain an accurate
and
useful real-time thermal profile of a glass sheet.
[0069] Positional sensors 320 and 321 are any device able to produce
data
representing the shape of a glass sheet. Non-limiting examples of positional
sensors
are CCDs and laser-light sensors, as are broadly known and commercially
available.
Data is obtained from the positional sensors 320 and 321 and is assembled by a
computer-implemented process to produce a shape profile of a glass sheet in
the
furnace 78. As indicated below, the positional data obtained from the
positional
sensor, and the shape profile produced from that data is compared to a
reference
shape profile in a computer-implemented process, and any differences between
the
produced shape profile and the reference shape profile triggers selective
heating of
27
CA 2994524 2018-03-09
the glass sheet by the gyrotron to match the shape profile of the glass sheet
with that
of the reference shape profile. Any number of positional sensors can be used,
so
long as meaningful data is obtained relating to the real-time shape profile of
the glass
sheet during the bending process. Likewise, more than one type of positional
sensor
can be used to obtain the produced shape profile so as to obtain an accurate
and
useful real-time representation of the glass sheet during the bending process.
For
example, two CCDs may be used to generate a stereoscopic shape profile of a
glass
sheet, while one or more laser distance sensor is used to determine the
spatial
location or orientation of one or more points on the surface of the glass
sheet in order
to best determine the degree of bending of the glass sheet at any time.
[0070] The obtaining and processing of thermal and shape data, and the
use
of those data to produce temperature and shape profiles may be repeated one or
more times during the bending process, e.g., at intervals ranging from every
0.0001
to 60 seconds, including every 0.0001, 0.001, 0.01, 0.1, 0.5, 1, 2, 5, 10, 15,
20, 30
and 60 seconds including any increment therebetween. Even shorter time
intervals
are contemplated, and are only limited by the throughput (e.g., processing
power) of
the computer system. The gyrotron system may not be able to respond to the
computer system as quickly as the computer system can analyze data, so
scanning
intervals may be set based on the responsiveness of the gyrotron system. That
said,
the scanning and analyzing of thermal and optionally spatial profiles can be
performed at faster rates than the controlling of the gyrotron, within limits
of the
pertinent hardware.
[0071] As is appreciated by those skilled in the art, during the shaping
of the
sheets, the entrance opening 290 of the first tunnel furnace 282 and the exit
opening
292 of the second tunnel furnace 288 can remain open. The doors to enter and
leave
the shaping furnace 286 are preferably opened to move the glass sheets to be
shaped into and out of the furnace 288, and during the shaping of the glass
sheets
in the shaping furnace 286, the doors (see Figs 5 and 6) are closed to
minimize heat
loss during the sheet shaping process. Optionally and within the scope of the
28
CA 2994524 2018-03-09
invention, the doors of the tunnel furnace can remain open for continuous
movement
of the glass sheets through the tunnel furnace to shape the glass sheets.
[0072] Fig.
15 shows schematically an example of the furnace system of Fig.
6. Details of Fig. 6 that are unnecessary to show operational and structural
differences between the furnace of Fig. 6 and that of Fig. 15 are omitted for
ease of
visualization, but are included in Fig. 15. As in Fig. 6, the furnace system
74 of Fig.
15 includes a first chamber 76, a second chamber 78, and a door 94 supported
by a
U-shaped member 136. The first chamber 76 preheats, through the use of
infrared
heaters, a glass sheet carried on conveyor 202, to a temperature within the
range of
900-1000 F, although other suitable preheat temperatures may be utilized
depending on the material of the glass sheet. In use, the glass sheet is
supported or
positioned on a bending iron (not shown, but as depicted and described
herein). The
second chamber 78, also herein referred to as a shaping chamber, selectively
heats
portions of the flat glass sheets to achieve a desired shape of the glass
sheet.
Infrared heaters of the second chamber 78 maintain the temperature of the
chamber
to about 1000-1100 F, or any temperature just below a shaping or sag
temperature
of the glass sheet. Specific portions of the sheet of glass are selectively
heated in
the second chamber 78 by a gyrotron beam system, including a gyrotron 177, an
optical box 178, and a mirror box 179. A benefit of the use of a high-energy
microwave system described herein is that the microwave source, e.g.,
gyrotron,
heats the glass sheet internally, and at precise locations on the glass sheet.
On the
other hand, traditional infrared heaters heat only the glass surface and
through heat
conduction, the energy passes into the glass. As a result, under traditional
infrared
heating the glass surface is significantly hotter than the internal glass
temperature,
hence increasing the likelihood of undesirable manufacturing conditions for
glass
bending. By "selective heating" it is meant that, the gyrotron beam system is
directed
to heat specific areas, portions, or locations of the glass to cause the glass
sheet to
sag, to produce a desired shape. Once the glass sheet is shaped to a desired
specification, it is controllably cooled. In the embodiment shown, the first
chamber
76 also serves as a cooling chamber for annealing the glass sheet, such that
once
29
CA 2994524 2018-03-09
the glass sheet is shaped in the second chamber 78, it is returned to the
first
chamber 76, where it is cooled in a controlled manner. The furnace system 74
can
include a third chamber on an opposite side of the second chamber 78 from the
first
chamber 76, and the conveyor 202 passes the glass sequentially from the first
chamber 76, through the second chamber 78, to the third furnace. The furnace
system 280 of Fig. 14 depicts an analogous orientation. Inclusion of a third
furnace
may simplify the process in that the glass sheet is able to move through the
system
in a linear manner. The third furnace is a cooling chamber which is able to
controllably cool the shaped glass sheet to anneal the shaped glass sheet. The
third
furnace may be modified such that the shaped glass sheet can be thermally
tempered or heat strengthened.
[0073] In addition to, or in lieu of, the pyrometer 204 shown in Fig. 6,
an
infrared sensor 324 can be provided. The pyrometer 204 and/or the infrared
sensor
324 monitor the temperature of the whole sheet of glass and/or specific
portions of
the glass. As used herein, a "portion" is an amount less than a whole or 100%
of an
object and can be a point, line, area, region, etc. on and/or in an object,
such as a
glass sheet.
[0074] The methods and systems described herein in one aspect rely on a
computer, for example like, but not limited to, a microprocessor 193, at least
for
monitoring and controlling progress of the heating and bending of the glass
sheets
described herein. A computer or computer system can take any physical form,
such
as a personal computer (PC), credit-card computer, personal digital assistant
(PDA),
smartphone, tablet, workstation, server, mainframe/enterprise server, etc. The
terms
computer, computer system, or microprocessor system, or computer
microprocessor
system are herein used interchangeably. A computer includes one or more
processors, e.g. a central processing unit (CPU), which carries out
instructions for
the computer. A computer also includes memory, e.g., RAM and ROM (storing,
e.g.,
the UEFI or BIOS), connected to the processor by any suitable structure such
as a
system bus. Computers also comprise non-transient storage for storing
programming
and data, in the form of computer readable medium/media, such as a hard drive,
a
CA 2994524 2018-03-09
solid state drive (SSD), an optical drive, a tape drive, flash memory (e.g., a
non-
volatile computer storage chip), a cartridge drive, and control elements for
loading
new software. Computer systems as described herein are not limited by any
topology or by the relative location of the various hardware elements,
recognizing the
varied physical and virtual structures those of ordinary skill employ in
implementing
a computer system.
[0075] Data, protocols, controllers, software, programs, etc., may be
stored
locally in the computer, e.g., in a hard drive or SSD; within a local or wide-
area
network, e.g., in the form of a server, a network associated drive (NAS); or
remotely,
such that connection is made over an internet connection, e.g., via remote
access.
Data, such as images, temperature profiles or shape profiles produced or used
by
the methods and systems described herein may be organized on computer readable
media in a database, which is an organized collection of data for one or more
purposes. Other exemplary hardware that form elements of a typical computer,
include input/output devices/ports, such as, without limitation: Universal
Serial Bus
(USB), SATA, eSATA, SCSI, Thunderbolt, display (e.g., DV! or HDMI) and
Ethernet
ports, as are broadly known, and graphics adaptors, which may be an integral
part
of the CPU, a subsystem of the motherboard, or as separate hardware device,
such
as a graphics card. Wireless communications hardware and software, such as Wi-
Fi
(IEEE 802.11), Bluetooth, ZigBee, etc. may also be included in the computer.
Elements of a computer need not be housed within the same housing, but can be
connected to a main computer housing via any suitable port/bus. In a typical
computer, at least the CPU, memory (ROM and RAM), input/output functionality,
and
often a hard drive or SSD and a display adaptor are housed together and are
connected by a high-performance bus of any useful topology.
[0076] The computer, having storage and memory capabilities, can include
controller aspects that allow for the design, storage, and execution of
instructions,
executable for independently or collectively instructing the computer system
to
interact and operate as programmed, referred to herein as "programming
instructions". In the context of computing, a computer-implemented process
(i.e.,
31
CA 2994524 2018-03-09
program), broadly speaking, refers to any computer-implemented activity that
generates an outcome, such as implementation of a mathematical or logical
formula
or operation, algorithm, etc.
[0077] One example of a controller is a software application (for
example,
basic input/output system (BIOS), unified extensible firmware interface
(UEFI),
operating system, browser application, client application, server application,
proxy
application, on-line service provider application, and/or private network
application)
installed on the computer system for directing execution of instructions. In
one
example, the controller is a WINDOWSTM - based operating system. The
controller
may be implemented by utilizing any suitable computer language (e.g., MC++,
UNIX
SHELL SCRIPT, PERL, JAVATM, JAVASCRIPT, HTML/DHTML/XML, FLASH,
WINDOWS NT, UNIX/LINUX, APACHE, RDBMS including ORACLE, INFORMIX,
and MySQL) and/or object-oriented techniques.
[0078] The controller can be embodied permanently or temporarily in any
type
of machine, component, physical or virtual equipment, storage medium, or
propagated signal capable of delivering instructions to the computer system.
In
particular, the controller (e.g., software application, and/or computer
program) may
be stored on any suitable computer readable media (e.g., disk, device, or
propagated
signal), readable by the computer system, such that if the computer system
reads
the storage medium, the functions described herein are performed.
[0079] The computer contains a "protocol", that is instructions and
data that
control e.g., the bending process for a glass sheet. Various modeling
techniques
may be used to develop protocols and may be implemented as part of a computer-
implemented protocol. Modeling techniques include scientific and mathematical
models, specific for glass bending processes, which are able to determine the
required temperatures at different stages of the process necessary to achieve
a final
glass sheet of high-quality. For example, the preheat temperature at the exit
of the
first furnace, glass forming/bending temperature profile in the glass forming
furnace,
exit glass temperature once the forming process is complete, and the glass
annealing
temperature. The protocol controls the gyrotron beam system to establish a
heating
32
CA 2994524 2018-03-09
profile to achieve a specific shape for a glass sheet. A gyrotron beam can be
manipulated in various ways, such as, altering the path, speed, width, shape,
frequency, dwell time at a location (position on the glass sheet), or
intensity/energy
(e.g., kilowatts, kW) of the gyrotron beam. In one embodiment, beam width,
beam
shape, intensity/energy and frequency is constant, but the location, path,
speed
and/or dwell time at a location of gyrotron beam are altered to provide a
desired
heating profile on the sheet. In another example, the gyrotron beam's
electrical
power can be manipulated, while the beam is moving at a constant speed across
the
surface of the glass sheet to produce desired heat profile. In another
example, one
can change both the electrical power and beam speed to achieve the same
effect.
The protocol comprises instructions at least for controlling any or all
possible
parameters of the gyrotron beam, such as: location, path, intensity/energy,
speed,
beam shape, beam diameter, and output frequency, which may be controlled by
the
gyrotron unit or the post-gyrotron optics. As such, a protocol controls the
heat-profile
and/or heat distribution on a glass sheet for attaining a desired shape and
size of the
sheet of glass. Included as part of the protocol, the computer receives and
processes
real-time data from the thermal and positional sensors, particularly the
thermal
sensor and, optionally the positional sensor. The computer then produces a
temperature profile, and optionally a shape profile from the real-time data.
The
temperature profile and shape profile are merely representations in the
computer that
can be compared to reference temperature and shape profiles stored in
association
with the bending protocol. The computer system compares produced profiles to
the
reference profiles to determine differences between the produced profiles and
the
reference profiles at one or more locations on the glass sheet, and, if
differences are
present and one or more positions on the glass sheet require heating to match
the
temperature and shape of the glass sheet to the reference profiles, the
computer
controls one or more parameters of the gyrotron beam to selectively heat a
portion
of the glass sheet to correct those differences. In addition to the above,
optionally,
the computer receives additional temperature data from one or more temperature
sensors, such as thermocouples or IR scanners of one or more chambers and/or
33
CA 2994524 2018-03-09
furnaces of the system according to any examples described herein, and acts as
a
thermostat, monitoring and adjusting the ambient temperature of the chamber,
e.g.,
by adjusting the output of IR heaters, blowers, etc. utilized in the system.
For
example, in one aspect, thermocouples (e.g., as shown in Fig. 6) detect the
temperature of the second furnace 78, as shown in Fig. 15. If the second
furnace 78
is not at the desired temperature, the computer, using computer-implemented
processes for example as described above, compares the actual ambient
temperature of the second furnace 78 to a stored reference ambient temperature
for
the second furnace 78, and automatically adjusts the heat of the second
furnace 78
in order to reach the stored reference ambient temperature. By
"ambient
temperature" in reference to the furnaces described herein, it is meant the
temperature of the atmosphere at one or more points within the furnace, and
does
not refer to the temperature of the glass sheet.
[0080] In
another aspect, the thermal sensor 324 is an IR laser-light sensor
that captures an IR image of the glass sheet being bent, which is sent to the
computer, which compares the captured image to a reference image stored as
part
of a glass bending protocol for the particular glass sheet, and, if a position
on the
glass is at a temperature lower than that of the same position in the image
stored as
part of a glass bending protocol, the gyrotron beam is directed to heat that
position
until the temperature of the position matches the reference temperature of the
image
stored as part of a glass bending protocol. As used herein, a protocol for
producing
a specific shape from a glass sheet contains one or more reference temperature
distribution profiles and shape profiles for the specific shape and glass
sheet at one
or more time points during the bending process.
[0081] Fig.
15 also depicts optional positional sensors 320. A suitable light
source to provide illumination of the glass sheet to the extent necessary to
permit
imaging also may be employed, though heated glass typically emits enough light
for
imaging purposes. The positional sensor(s) comprises a single unit or multiple
units
that allow for either image capture or capture of data in real time,
indicating the spatial
position of one or more positions on the glass sheet. A non-limiting example
is a
34
CA 2994524 2018-03-09
positional sensor obtained from Rockwell Automation (Allen Bradly), for
example, the
42CM 18 mm LaserSight or the 42EF LaserSight RightSight are suitable
positional
sensors. The positional sensor can be an imaging sensor, such as one or more
CCD
and/or laser-light sensor devices housed either together or at separate
locations
within the chamber 78. CCD and/or laser-light sensor devices sensor devices
output
2D images that are processed within the computer or within the device. The
images
can be used in their 2D form, or can be processed to form a 3D image by the
computer to produce a profile of the glass sheet that indicates the real-time
spatial
position and shape of any portion or point on the glass sheet, and then
compares
that 2D profile to a reference profile associated with the protocol, and
adjusts heating
with the gyrotron beam to match the shape profile of the glass sheet with the
reference profile. A large variety of position, distance, measurement,
displacement,
profile, 2D, and 3D sensors, e.g., laser sensors, are commercially available,
for
example and without limitation from Rockwell Automation (Allen Bradly),
Emerson
Electric of St. Louis Missouri, Schmitt Industries, Inc. of Portland Oregon,
and Omron
Automation & Safety of Hoffman Estates, Illinois. In any case, the positional
sensor
is connected to the computer, and data obtained from the positional sensor,
optionally in coordination with the IR data described above, and that data is
compared to reference data associated with a protocol for bending a particular
glass
sheet, and the temperature of any portion of the glass sheet can be adjusted
using
the gyrotron beam.
[0082] As
shown in Fig. 15, two positional sensors 320, 321, are shown. A
composite 3D image or set of images of the glass sheet at any given time point
can
be generated by a computer implemented process so as to evaluate the shape of
the glass sheet at any time point. The computer system generated 3D image,
composite image, or set of images of the glass sheet and/or a portion thereof
can be
compared to values of the reference shape profile of the protocol, and if a
deviation
from the desired shape stored in the protocol is present, the computer system
controls the gyrotron 177 and/or ambient temperature of the second furnace 78,
optionally in combination with infrared image data from the 2D infrared
imaging
CA 2994524 2018-03-09
sensor 324 to heat the glass sheet, or portions thereof, to shape the glass
sheet to
meet the requirements of the recipe. Fig. 16 provides a flowchart illustrating
a non-
limiting embodiment of the methods described herein employing two or three
chambers as discussed in relation to Fig. 15.
[0083] A gyrotron beam can be manipulated in various ways, such as,
altering
the path, speed, width, frequency, dwell time at a location, or energy
intensity or
electrical power of the gyrotron beam. In one example, beam width, energy and
frequency is constant, but the location, path, speed and/or dwell time at a
location of
gyrotron beam are altered to provide a desired heating profile on the sheet.
[0084] A "temperature profile" or "temperature distribution profile"
refers to the
temperature of any portion or portions of a specific glass sheet at any time
point or
points during the process of heating, bending and cooling that sheet of glass.
As
used herein, a "reference temperature profile" refers to a temperature
distribution
profile for any specific glass sheet stored locally in or remotely from the
computer
system in association with a protocol for bending that specific glass sheet.
The
reference temperature profile is created or developed by any method, such as
by
formula and/or trial-and-error, to produce a specific shape of the specific
glass sheet.
The reference temperature distribution profile for producing a desired shape
from a
glass sheet will depend on a variety of factors, including, among other
factors: the
composition of the glass sheet, the desired shape, and the bending iron shapes
and
functionality. By using a predetermined temperature profile as a reference,
and
ultimately manipulating the gyrotron system to selectively heat the sheet of
glass, an
even glass viscosity distribution is produced not only inside of the glass,
but
throughout the glass. This even distribution of glass viscosity eliminates
overheating
of the glass surface and as a result, the glass sheet will be formed or bend
into
required shape with a satisfied optical quality.
[0085] The terms "shape profile" refers to the 2D or 3D shape of a
glass sheet
at any time point or points during the process of heating, bending and cooling
a sheet
of glass. A "reference shape profile" refers to a shape profile for any
specific glass
sheet for any time point in the glass forming process stored locally in or
remotely
36
CA 2994524 2018-03-09
from the computer system in association with a protocol for bending that
specific
glass sheet. The reference shape protocol is created or developed by any
method,
such as by formula and/or trial-and-error, to produce a specific shape of the
specific
glass sheet. As with the predetermined heat distribution, the reference shape
profile
for producing a desired shape from a glass sheet will depend on a variety of
factors,
including, among other factors: the composition of the glass sheet, the
desired
shape, the bending iron shapes and functionality.
[0086] The invention further contemplates the use of safety equipment
to limit
or prevent damage to the persons operating the equipment, and/or to prevent or
limit
damage to the equipment. For example and not limiting to the discussion, the
equipment includes an arc detector 330. The arc detector 330 is mounted in the
furnace 78 and included a photocell connected to the microprocessor 193 by way
of
the cable 306. The arcing, as is known in the art, is ionized matter, e.g. but
not limited
to an air born pocket of dust and appears as a burst of light. The arcing
phenomenon
is well known in the art and no further discussion is deemed necessary. The
photocell
of the detector 330 senses the arcing and forwards a signal along the cable
305. The
microprocessor 193 forwards a signal along the cable 308 to shut the gyrotron
down
to prevent damage to the personnel around the furnace 78 and to the gyrotron
equipment.
[0087] The examples of the invention were discussed to shape two glass
sheets. As can now be appreciated, the invention is not limited thereto and
the
invention can be practiced on one sheet, or more than two sheets, e.g. but not
limited
to three, four or more sheets.
[0088] The invention can be further characterized in the following
numbered
clauses.
[0089] Clause 1: A method of shaping a glass sheet comprising:
a. preheating a glass sheet on a bending iron (70) to a
preheating
temperature ranging from 600 F to 1000 F;
37
CA 2994524 2018-03-09
b. increasing the temperature of the sheet to a temperature
ranging from greater than the preheating temperature to less than a
temperature at which the glass sags;
c. bending the glass sheet by:
selectively heating a portion of the glass sheet with a
device (177) that produces ultra-high frequency, high-power
electromagnetic waves controlled by a computer-implemented
protocol to a temperature at which at least a portion of the glass sheet
sags;
scanning at least a portion of the glass sheet with one or
more thermal sensors (324) at one or more time points during or after
the selectively heating step and obtaining from data obtained from the
one or more thermal sensors (324) a temperature distribution in at least
two dimensions for at least a portion of the glass sheet;
comparing, using a computer-implemented process the
obtained temperature distribution to a reference temperature
distribution of the computer-implemented protocol; and
iv. selectively heating the glass sheet with the beam (225)
of the ultra-high frequency, high-power device (177) controlled by a
computer-implemented process to match the obtained temperature
distribution with the reference temperature distribution of the computer-
implemented protocol.
[0090] Clause 2: The method of clause 1, wherein the device
producing
ultra-high frequency, high-power electromagnetic waves (177) is a gyrotron.
[0091] Clause 3: The method of clauses 1 or 2, further
comprising
repeating steps ii. through iv. of the bending step until the obtained
temperature
distribution matches the reference temperature distribution of the computer-
implemented protocol.
[0092] Clause 4: .. The method of any one of clauses 1-3, in
which bending
step c. further comprises:
38
CA 2994524 2018-03-09
v. obtaining positional data of at least a portion of the glass
sheet from one or more positional sensors (320 and 321) at one or
more time points during the selective heating step and producing a
shape profile using a computer-implemented process for the glass
sheet at the one or more time points;
vi. comparing, using a computer-implemented process a
produced shape profile to a reference shape profile of the computer-
implemented protocol; and
vii. selectively heating the glass sheet with the beam (225)
of the ultra-high frequency, high-power device (177) controlled by a
computer-implemented process to match a shape profile of the glass
sheet to the reference shape profile.
[0093] Clause 5: The method of clause 4, further comprising
repeating
steps v. through vii. of the bending step until the obtained shape profile
matches the
reference shape profile of the computer-implemented protocol.
[0094] Clause 6: The method of clauses 4 or 5, wherein comparing
steps
iii. and vi. are performed substantially concurrently.
[0095] Clause 7: The method of any of clauses 4 to 6, in which one
or
more of the positional sensors (320 and 321) is a camera or charge-coupled
device
(CCD).
[0096] Clause 8: The method of clause 7, wherein the shape profile
is a
three-dimensional shape profile assembled from data obtained from a plurality
of
CCDs.
[0097] Clause 9: The method of clause 7, wherein the shape profile
is a
three-dimensional shape profile assembled from data obtained from a plurality
of
laser-light sensors.
[0098] Clause 10: The method of any of clauses 4 to 9, wherein one or
more of the one or more positional sensors (320 and 321) are laser-light
sensors.
[0099] Clause 11: The method of any of clauses 1 to 10, wherein the
glass
sheet is cut-to-size prior to heating and shaping.
39
CA 2994524 2018-03-09
[00100] Clause 12: The method of any of clauses 1 to 11, in which the
thermal sensor (324) is an IR scanner or and IR imaging sensor, optionally a
laser-
light sensor.
[00101] Clause 13: A system comprising:
a first furnace (76) comprising infrared heaters (172) and temperature sensors
(191); and
a second furnace (78) comprising infrared heaters (172), a device that
produces ultra-high frequency, high-power electromagnetic waves (177), and an
optical system for controlling shape, location and movement of a beam of the
device
to a glass sheet on a bending iron within the second furnace (78), and one or
more
infrared (IR) imaging sensors;
a conveyor system for carrying a glass sheet on a bending iron (70) through
the first and second furnaces (76 and 78);
a computer system connected to the one or more IR imaging sensors and the
ultra-high frequency, high-power device (177), comprising a processor and
instructions for controlling bending of a glass sheet in the second furnace
(78) by
selective heating by the ultra-high frequency, high-power device (177), the
instructions comprising a computer-implemented protocol for heating and
bending a
glass sheet in the second furnace (78), where the computer system obtains a
temperature profile of the glass sheet at one or more time points during the
bending
of the glass data from the one or more IR imaging sensors (324), compares the
obtained temperature profile to a reference temperature distribution of the
computer-
implemented protocol, and controls the ultra-high frequency, high-power device
(177) to selectively heat the glass sheet to match the reference temperature
distribution; and
a third heating furnace (260) to controllably cool the glass sheet, comprising
IR heaters, a forced cool air convection system, and air fans.
[00102] Clause 14: The system of clause 13, wherein the device producing
ultra-high frequency, high-power electromagnetic waves (177) is a gyrotron.
CA 2994524 2018-03-09
[00103] Clause 15: The system of clauses 13 or 14, further comprising
one
or more positional sensors (230 and 231) in the second furnace (78) arranged
to
obtain positional data for one or more portions of the glass sheet during
bending,
wherein the positional sensors (230 and 231) are connected to the computer
system
and the computer system:
a. obtains data from the one or more positional sensors (230 and
231) at one or more time points during the bending of the glass sheet;
b. produces a shape profile for the glass sheet from the obtained
data from the one or more positional sensors at the one or more time
points;
c. compares the obtained shape profile to a reference shape
profile of the computer-implemented protocol; and
d. controls the ultra-high frequency, high-power device (177) to
selectively heat the glass sheet to match a shape profile of the glass
sheet to the reference shape profile.
[00104] Clause 16: The system of clause 15, wherein one or more of the
one
or more positional sensors (230 and 231) is a charge-coupled device (CCD).
[00105] Clause 17: The system of clause 16, comprising a plurality of
CCDs,
wherein the shape profile is a three-dimensional shape profile assembled from
data
obtained from the plurality of CCDs.
[00106] Clause 18: The system of any of clauses 15 to 17, wherein one or
more of the one or more positional sensors (230 and 231) are laser-light
sensors.
[00107] Clause 19: The system of clause 18, comprising a plurality of
the
laser-light sensors, wherein the shape profile is a three-dimensional shape
profile
assembled from data obtained from the plurality of CCDs.
[00108] Clause 20: The system of any of clauses 13 to 19, wherein one or
more of the one or more IR imaging sensors (324) is a laser-light sensor or a
CCD.
[00109] Clause 21: The system of any of clauses 13 to 20, further
comprising
a third furnace (260) having IR heaters, and wherein the conveyor system
further
carries the glass sheet through the third furnace.
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[00110] Clause 22: The system of clause 21, wherein the first, second
and
third furnaces (76, 78 and 260) form a single tunnel.
[00111] Clause 23: The system of clause 22, comprising doors between the
first and second furnaces (76 and 78) and between the second and third
furnaces
(78 and 260).
[00112] Clause 24: The system of any of clauses 13 to 23, in which the
computer system obtains a temperature of the first furnace and adjusts the
temperature of the first furnace (76) using the IR heaters to match a
preheating
temperature according to the computer-implemented protocol.
[00113] Clause 25: The system of any of clauses 13 to 24, in which the
computer system obtains an ambient temperature of the second furnace (78) and
adjusts the temperature of the second furnace (78) using the IR heaters to
match a
temperature ranging from greater than the preheating temperature to less than
a
temperature at which the glass sags.
[00114] It will be readily appreciated by those skilled in the art that
modifications
can be made to the non-limiting embodiments of the invention disclosed herein
without departing from the concepts disclosed in the foregoing description.
Accordingly, the particular non-limiting embodiments of the invention
described in
detail herein are illustrative only and are not limiting to the scope of the
invention,
which is to be given the full breadth of the appended claims and any and all
equivalents thereof.
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