Glass sheet manufacturing method and apparatus

An glass manufacturing process and apparatus having a vertical air-cooled electric furnace and a transverse air-cooled refiner section. The furnace and the refiner are provided with a plurality of molybdenum plate electrode cartridge assemblies. Molten glass is removed from the furnace refiner section by means of a plurality of basin cylinders symmetrically disposed within the transverse refiner. An extruder mechanism accepts molten glass from each basin cylinder and applies the molten glass to a pair of extrusion rolls and onto a molten tin bath. The extrusion rolls are eccentrically pivoted off-center such that the separation distance between them can be varied. A cutting frame is then lowered over the tin bath such that the molten glass sheet is held firmly while it is cut into lite sizes by a cutting mechanism. After cutting, a transfer unit having suction orifices is lowered over the glass sheet and lifts the newly cut glass sheet either to an annealing stage or to a tempering stage. The cut glass sheet then undergoes electronic inspection and packaging.

BACKGROUND OF THE INVENTION 
1. Field of the Invention: 
This invention relates to apparata and methods for manufacturing finished 
flat glass products. More particularly, this invention involves automated 
and energy efficient improvements in the design of electric furnaces and 
refiners, glass sheet formation, glass cutting devices, and in glass 
transfer and tempering mechanisms. 
2. Description of the Prior Art: 
Various techniques are presently being used to manufacture flat sheet 
glass. Typically, premixed glass-forming materials are fed onto the 
surface of a bath of molten glass contained in a furnace. In the fuel 
firing of the regenerative tank type furnaces, the materials are melted by 
hot gases from flames playing across the furnace above the glass surface. 
In the more modern electric furnaces, heat is produced by passing electric 
current through the bath of molten glass between electrodes immersed in 
the glass. Also, a combination of both heating methods are sometimes 
employed. 
The furnaces described above assume various shapes. Early regenerative, 
fuel fired, tank type furnaces were generally horizontal and rectangular 
in shape with raw material received in one end and molten glass formed in 
a continuous sheet on the opposite end. This furnace at one time enjoyed 
considerable popularity in view of the abundance of relatively cheap 
natural gas energy resources. However, as natural gas fuel became scarce 
and therefore expensive, the energy consumption deficiencies of the 
regenerative furnace soon became apparent. In particular, the horizontal 
regenerative furnace experienced considerable heat loss because of its 
relatively large exposed cross-sectional areas. Therefore the trend in 
recent years has been to employ vertical electric furnaces. These furnaces 
are characterized by smaller cross-sectional area, and therefore less heat 
loss. However these furnaces likewise have not been without problems. A 
perennial problem with electric furnaces has been heat localization around 
the electrodes, and the integrity of the furnace walls surrounding the 
localized electrode heat pockets. Furtheremore, normal electrode wear 
requires regular replacement, which has resulted in shut-down of the 
furnace. 
In conventional glass manufacturing furnaces, the glass batch after being 
melted in the furnace is refined in adjacent refining and melting 
sections. The adjacent refining section, normally equipped with auxiliary 
heating means, provides a zone for temperature equalization whereby air 
bubbles are eliminated and glass homogeneity is effected. Typical glass 
melting furnaces and refiners are found in U.S. Pat. Nos. 3,636,227; 
3,936,290; 3,997,316; 3,998,619; 4,011,070; 4,012,218. Typical glass 
furnace electrode assemblies are found in U.S. Pat. Nos. 2,798,892; 
2,978,526; 3,409,725; 3,517,107; 3,576,385; 3,681,506; 3,740,445; and 
3,813,468. 
After reaching a state of equilibrium within the refiner stage, the molten 
glass is withdrawn from the refiner. In the Pittsburgh or Pennvernon sheet 
glass drawing apparatus a series of pairs of rolls provide tractive force 
which draws glass upwardly from a bath of molten glass. The thickness of 
the continuous ribbon of glass is maintained by the speed of the rolls 
drawing the semi-molten glass from the reservoir. As shown in U.S. Pat. 
No. 3,420,650 molten glass flows out of the furnace through an aperture in 
the wall of the furnace and into the bite of a pair of forming rolls which 
form the molten glass into a continuous ribbon. In the float process, the 
glass sheet passes from the furnace to forming rolls which determine 
thickness, and then flows onto a molten tin bath which imparts an ideal 
flatness to the glass ribbon. In the float process, glass thickness is 
further controlled by manipulating the glass temperature and speed of 
advancement to longitudinally stretch the glass, or by installing 
longitudinally extending fenders within the molten metal bath structure to 
limit the lateral spreading of the glass as it advances across the molten 
bath. While these techniques have proven satisfactory in the past, the 
reproducibility of a precise glass ribbon thickness has been difficult, 
primarily because of the rather imprecise metering of the molten glass 
from the furnace. 
In conventional glass manufacturing plants, when the glass ribbon is 
removed from the molten metal bath, it then enters a covered annealing 
lehr where the temperature of the glass is lowered gradually from the 
semi-molten state to a rigid and near room temperature cooled glass. The 
length of the annealing lehrs used in the prior art varies, with some 
lehrs being several hundred feet in length. The annealing process results 
in a hardened manageable glass product that can be cut with a diamond or 
scoring wheel. However, at this stage in the glass manufacturing process, 
the annealed glass is lacking of impact strength and is susceptible to 
breakage. Also, when breakage occurs, the annealed glass usually breaks 
into hazardous jagged fragments. 
After annealing, which to a certain extend occurs naturally as the glass is 
removed from the molten metal bath, it may be desirable to submit the 
glass ribbon to a tempering process which results in a safety glass. To 
temper glass, it is necessary to reheat the glass from the annealed state 
and to return the glass to semi-molten temperatures. Thereafter, sudden 
chilling of the glass sheet on both sides, simultaneously, with cold air 
or oil is required. This tempering phase improves the impact strength of 
the glass sheet by a factor of 4 over the annealed glass sheet. Moreover, 
when tempered glass is broken, it breaks into relatively harmless, 
"marble" shaped pieces, rather than the dangerous sharp pointed fragments 
of broken annealed glass. Unfortunately, the glass sheet once tempered 
cannot be recut with the ease of the annealed product, and therefore 
tempered glass is to a larger extent subject to breakage when being cut. 
It has therefore become necessary that the desired size of the sheet be 
exact before the tempering phase is performed. Typical methods and 
apparata for tempering glass sheets are disclosed in U.S. Pat. Nos. 
3,488,173; 3,647,409; 3,734,706; 3,841,855; 3,875,766; 3,881,906; 
3,923,488; 3,994,711; 3,929,442; and 4,004,901. 
In conventional glass cutting apparata, the glass sheet is typically cut by 
scoring the sheet and then severing the sheet along the score line. 
Generally, glass sheets of different size are cut by multiple passes of 
the scorer/severing device. In order to increase the glass production 
rate, cutter mechanisms of the prior art were reciprocated across the 
glass ribbon at increased velocity. However, because of the proportionally 
irregular quality of the high velocity cuts, other techniques were 
developed for increasing production. As disclosed in U.S. Pat. No. 
3,703,115 the cutting means is transported in the same direction as the 
moving glass ribbon and at substantially the same velocity. As a result, 
the reciprocating velocity of the cutting means can be discriminately 
selected. Nevertheless, however, this improvement in cutting speed is 
limited by the existence of only a single cutting mechanism, and the 
overall complexity of the system is increased as a result of these 
velocity control mechanisms. 
U.S. Pat. No. 3,983,771 discloses an apparatus for precise subdivision of 
glass sheets. The subdivision is accomplished by combining the functions 
of wheel holders and spacing means in a row of spacer blocks whose 
contiguous surfaces are ground flat and polished with a high degree of 
accuracy, thereby establishing the spacing between scoring wheels to a 
high degree of accuracy. Unfortunately, with this cutting scheme, spacer 
blocks must be manually moved or replaced in order to change the spacing 
between adjacent scores. Predictably, this feature results in decreased 
flexibility of the glass cutting operation. Other glass cutting inventions 
which are considered to be of interest are disclosed in U.S. Pat. Nos. 
3,165,017; 3,424,357; 3,754,884; 3,934,995; 4,004,900; and 4,010,677. 
SUMMARY OF THE INVENTION 
Accordingly, it is the primary object of this invention to provide novel 
methods and apparata for manufacturing sheet glass which are free of the 
above-noted disadvantages. 
Another object of this invention is to provide a new and improved glass 
manufacturing furnace. 
A further object of this invention is to provide an air-cooled electric 
furnace with improved maintenance characteristics. 
Another object of this invention is to provide an improved electric furnace 
with a transverse refiner section which is likewise air cooled and which 
therefore also is subject to reduced maintenance requirements. 
A further object of this invention is to provide a new and improved method 
and apparatus by which molten glass is metered from the furnace refiner 
section. 
Another object of this invention is to provide new and improved glass sheet 
formation apparatus and methods. 
A further object of this invention is to provide a new method and apparatus 
for cutting glass sheets. 
Another object of this invention is to provide a novel method and apparatus 
for cutting glass sheets while the newly-formed sheets are still in a 
semi-molten state. 
Another object of this invention is to provide a novel glass cutting method 
and apparatus by which the glass is cut before it is temperature treated 
in subsequent tempering or annealing stages. 
A further object of this invention is to provide a new glass cutting 
apparatus by which a newly-formed glass sheet can be automatically cut 
into a plurality of smaller predetermined sizes with a high degree of 
precision. 
Another object of this invention is the provide a novel method and 
apparatus for transferring and tempering newly-formed glass sheets. 
A further object of this invention is to provide a new and improved casing 
which houses the plurality of electrodes employed in the electric furance. 
Another object of this invention is to provide a novel glass manufacturing 
apparatus and method which requires a minimum number of human operators, 
and which is controlled from a central control center. 
These and other objects of the present invention are achieved by providing 
an all-electric glass manufacturing process and apparatus having a 
vertical air-cooled electric furnace and a transverse air-cooled refiner 
section. The furnace and the refiner are provided with a plurality of 
molybdenum electrode cartridges housed in lock-in cartridge casings 
designed to facilitate electrode removal. Molten glass is removed from the 
furnace refiner section by means of a plurality of basin cylinders 
symmetrically disposed within the transverse refiner. The basin cylinders 
are provided with a plurality of open faces which receive molten glass 
from the furnace refiner and which upon rotation of the basin cylinder 
delivers a prescribed amount of molten glass to an extruder mechanism. The 
extruder mechanism accepts molten glass from the basin cylinder and 
applies the molten glass to a pair of extrusion rolls. The extrusion rolls 
are eccentrically pivoted off-center such that the separation distance 
between them can be varied in accordance with the desired thickness of the 
sheet glass being formed. The entire extruding mechanism including the 
extruder rolls is mobile such that as molten glass is extruded through the 
extruder rolls it is deposited on a molten tin bath which imparts an ideal 
smoothness to the surface of the newly-formed glass sheet. A cutting frame 
is then lowered over the tin bath such that the molten glass sheet is held 
firmly between a flange on the cutting frame and a flange on the tin bath. 
Thereafter, the molten glass sheet is cut into lite sizes by a cutting 
mechanism having a plurality of discrete glass cutting block assemblies, 
each of which is independently adjustable to a resolution of 1/32 inch. 
These cutting block assemblies are housed in two cutting carriages which 
alternately sweep the length and width of the newly formed glass sheet 
while the sheet is stationary on the tin bath. After cutting, a transfer 
unit having a plurality of suction orifices connected to a reversible 
vacuum source is lowered over the glass sheet. The transfer unit lifts the 
newly cut glass sheet off the tin bath and transfers the glass sheet 
either to an annealing stage or to a tempering stage. Notably, the 
transfer unit is also used for tempering, with the reversible vacuum 
source applying cold air to the glass sheet. After temperature treatment, 
the glass sheet cut to lite sizes undergoes electronic inspection and 
packaging. The entire process is under the control of a minimum of 
operator personnel located in a central control center.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawings, wherein like reference numerals designate 
identical or corresponding parts throughout the several views, and more 
particularly to FIG. 1 thereof, there is provided an overview of the glass 
manufacturing apparatus of the present invention which includes the 
vertical air cooled electric furnace 2, the transverse air cooled furnace 
refiner 4, the glass metering basin cylinders 6, the glass extruder 
mechanisms 8, molten tin baths 10, tempering chambers 12, glass sheet 
transfer area 14, tempering lehrs 16, annealing lehrs 18, packaging areas 
22, and control center 24. Many of these component parts of the glass 
manufacturing apparatus of this invention are also shown in FIG. 2 in 
which the glass cutting frame 26 and the mobile transfer and tempering 
unit 28 is viewed. As shown in FIG. 2, the glass manufacturing parts 
listed above are supported on a steel structure 30. 
The operation and structure of the vertical air cooled electric furnace 
with its transverse air cooled refiner section is now described with 
reference to FIGS. 1-3. As seen in these figures, the walls 32 of the 
electric furnace 2 are provided with an inside lining 34 made of 
refractory brick. Surrounding the refractory brick lining 34 is steel 
frame 36 which provides mechanical support to the vertical furnace 2 and 
which in effect contains the furnace 2. Steel frame 36 consists of inner 
and outer steel plate linings 38. Steel separators 40 are provided between 
steel plate linings 38 thereby forming air cooling passageways 42 between 
steel plate linings 38. A plurality of molybdenum plate electrodes 44 are 
provided as circuit pairs at various levels of vertical furnace 2 and 
transverse refiner 4. Removable preheating electrodes 54 which are used 
during furnace start-up conditions are located just above the floor 55 of 
vertical furnace 2. Also provided near the floor 48 of furnace 2, but not 
shown, is a cullet drain and a sediment sump. 
Molybdenum electrodes 44 are selected as the primary glass heating elements 
because of their relatively large glass contact areas. This reduces 
current density in the vicinity of the electrode, and thus results in 
greater resistance to erosion. The electrodes 44 exhibit a relatively long 
service life, thereby minimizing furnace maintenance requirements. 
Each electrode 44 is assembled in cartridge form. Each cartridge assembly 
as shown in FIG. 4a consists of a molybdenum electrode plate 45, a rigid 
conductor 46 connected to the electrode plate 45 at one end and provided 
with a connector terminal 47 at the other end thereof, and an insulation 
lining 48 which surrounds the rigid conductor 46 and fits flush between 
the electrode plate 45 and the terminal 47. The insulation lining 48, made 
of a ceramics material, mechanically protects the plate 45 and conductor 
46 during handling, while electrically and thermally isolating the 
electrode assembly 44 from the furnace structure. 
As shown in detail in FIG. 4, each electrode cartridge assembly 44 is 
housed in an electrode casing 49 which protrudes through furnace wall 32. 
Electrode cartridge 44 is inserted in casing 49 with its molybdenum plate 
protruding within the furnace. Since electrode 44 is tight fitting within 
casing 49, molten glass is prevented from lodging or seeping between the 
cartridge 44 and the casing 49. Electrode casing 49 is tubular in shape, 
with an opening at one end 41 in communication with the interior of the 
electric furnace 2. The other end 43 of the tubular casing 45 is provided 
with an electrode cartridge lock-in mechanism, which consists of lock-in 
doors 50 hingedly connected to the end 43 of casing 49. The lock mechanism 
also features a pair of latching hooks 51a on either side of the lock-in 
doors 50, and a latch catch 51b which engages each latch hook 50a, thereby 
locking the doors and maintaining furnace electrode 44 in proper position 
during furnace operation. Furthermore, each electrode cartridge casing 49 
is also provided with a casing cutoff 52 which prevents molten glass 
escape during electrode replacement. The casing cutoff 52 is manually 
operable by means of the two way ratched cutoff lifting mechanism 53. 
Also, as seen in FIG. 4, electrode casing 49 is in communication with air 
cooling passageway 42. This factor in combination with the insulation 
lining 48 prevents excessive localized heating in the furnace walls in the 
vicinity of the electrode assemblies and thus improves the service life of 
the furnace structure which in turn minimizes system down time. 
Furthermore, electrode cartridge replacement is effected on line, without 
system down time, thereby further enhancing system utilization. 
During furnace start-up, removable electric resistance preheating 
electrodes 54 are inserted inside the vertical furnace 2 through the 
furnace walls 32 just above the furnace floor 55. Raw glass batch material 
is then gently lowered into the furnace by means of portable furnace 
intake chute 56, shown in FIG. 2, to a level 56 just below the first set 
of molybdenum plate electrodes. Preheating electrodes 46 are then 
energized, thus melting the initial batch materials in vertical furnace 2. 
Thereafter, additional batch material is successively entered into the 
furnace via chute 56 to levels 57-62 whereupon each opposed pair of 
molybdenum electrodes just below these levels are successively and 
respectively energized by applying 220 volt 60 cycle electrical power 
across each electrode pair. Electric current then flows between each 
electrode pair, thus resulting in heating and melting of the glass batch 
materials between each electrode pair. It is noted that the relatively 
large surface area of each molybdenum plate 45 decreases the current 
density in the immediate vicinity of the plate 45, thereby decreasing 
erosion of the electrode plate 45. Removable preheating electrode 46 are 
withdrawn from the furnace 2 upon completion of the start-up cycle. 
As shown in FIG. 2, electric furnace 2 communicates with transverse refiner 
section 4 via furnace throat section 66 which forms a passageway for the 
flow of molten glass from the furnace 2 to the refiner 4. When the 
prescribed melting temperature is obtained in the furnace 2, throat 
cut-off 68 is opened to allow molten glass flow to the preheated 
transverse refiner 4. Thereafter, proper glass levels are maintained 
within the vertical furnace 2 and the transverse refiner 4 by adding new 
raw batch materials to the vertical furnace 2 in equal proportion to the 
molten glass withdrawn from the vertical furnace 2 into the refiner 4 via 
throat 66. Molybdenum electrode cartridges 44 are also provided in the 
transverse refiner 4 at level 70 in order to maintain the required molten 
glass temperature. It is noted that while the vertical electric furnace 
temperature is maintained at approximately 2600.degree. to 2900.degree. 
F., the transverse refiner temperature is maintained in the range of 
1800.degree. to 2200.degree. F. 
Molten glass level in the transverse refiner section is maintained at a 
prescribed level 72 within the refiner 4 by means of throat cut-off 68. As 
shown in FIG. 5, the transverse refiner molten glass is maintained at a 
prescribed level 72 by means of a float device 76. This float device 76 
floats on the surface of the molten glass within the transverse refiner 4, 
and rises or falls in accordance with this level. The vertical position of 
the float device 76 is monitored external to the refiner 4 by float 
position indicator 77. Indicator 77 generates an electrical feedback 
signal to throat cut-off 68, which is then raised or lowered to maintain 
the prescribed refiner glass level 72. Indicator 77 also generates an 
electrical signal representative of the actual refiner glass level, and 
this signal is displayed in the control center 24. The refiner glass level 
control mechanism shown in FIG. 5 assures a prescribed glass level at 72, 
and therefore avoids molten glass flooding or a highly pressurized glass 
flow which might otherwise occur in the absence of refiner glass level 
controls. This prescribed refiner glass level 72 is established by the 
human operator in control center 24, and can be varied according to the 
characteristics of the particular glass melt within the refiner 4. 
Glass of a particular sheet thickness as selected by the operator in 
control center 24 is produced by means of the apparatus shown in FIG. 6. 
As seen in FIG. 6, this apparatus includes the basin cylinder 6 and the 
glass extruder 8. As seen in FIGS. 1 and 6, a pair of basin cylinders are 
located at either end of the furnace transverse refiner section 4. The 
basin cylinder is of cylindrical shape and is partitioned into three 
equally dimensioned molten glass dispensing chambers 78. Chambers 78 are 
separated by three radially extending partitioning fins 80 which are 
connected at the center of the basin cylinder and extend the entire length 
of the basin cylinder. Radial fins 80 form 120.degree. angles between 
adjacent fins. Connected to partitioning fins 80 and extending the length 
of the basin cylinder are molten glass catching pieces 82 which form 
60.degree. arcs around the circumference of basin cylinder 6. As seen in 
FIG. 6, the basin cylinder glass dispensing chamber 78 is formed by 
partitioning fins 80 and glass catching pieces 82. Each dispensing chamber 
78 is provided with an open face 84. As the basin cylinder 6 is rotated, 
molten glass enters the open face 84 of the plural glass dispensing 
chamber 78, thereby forming a glass glob charge which exits the transverse 
refiner 4 and the basin cylinder 6 through the refiner exit 86. 
As shown in FIG. 6, metered glass globs are delivered from the basin 
cylinder 6 to the mobile extruder carriage 88. The extruder carriage 88 
houses the extruder mechanisms 8 shown in FIG. 1. These mechanisms include 
a glass glob storage chute 90, a glass extruder device 92, and glass sheet 
rollers 94 and 96. The extruder device 92 includes an extrusion bar 98, 
which travels in the extrusion bar chamber 100; extrusion pistons 102 
attached to the extrusion bar 98 by means of rigid rods 101; and a hinged 
molten glass intake valve which admits molten glass from the glass glob 
storage chute 90 to the extrusion bar chamber 100. 
The operation of the extruder mechanisms 8 is now described. A prescribed 
amount of molten glass, as determined by the number of revolutions of the 
basin cylinder 6, is delivered to the glass glob storage chute 90. Hinged 
intake valve 104 is in its vertical position as the prescribed amount of 
molten glass is metered into the storage chute 90 by the multiple 
clockwise revolutions of the basin cylinder 6. Basin cylinder 6 is halted 
upon the prescribed number of revolutions, and hinged intake valve 104 is 
then placed in its open, horizontal position. Thereupon the extruder 
intake stroke is commenced, whereby the extruder bar 98 is raised from its 
lower position 106 to its upper position 108. The molten glass charge 
stored in chute 90 is then drawn by suction into the extrusion bar chamber 
100. Upon completion of the extruder intake stroke, hinged valve 104 is 
closed to its vertical position, and the extruder device 92 commences its 
extrusion stroke. During the extrusion stroke, the extrusion bar is 
lowered from its upper position 108 to its lower position 106 thereby 
forcing the glass charge between glass sheet rollers 94 and 96. As seen in 
FIG. 6, roller 94 is mounted on the extruder carriage 88 by means of 
roller support beam 110. On the other hand, glass sheet roller 96 is 
eccentrically pivoted with respect to roller 94 at pivot point 112 by 
means of pivot support arm 114. As a result, when roller 96 is raised or 
lowered, the distance separating rollers 94 and 96 narrows or widens in 
accordance with the arc traveled by support arm 114. In this way, the 
thickness of the extruded glass is precisely maintained. Once again 
referring to FIG. 6, the molten glass charge is forced from the extrusion 
bar chamber 100 between rollers 94 and 96 during the extrusion stroke of 
the extruder device 92. Hinged flexible sleeve roll seals 115 and 117 
contact the rollers 94 and 96 at points 116 and 118 respectively and 
prevent pressure escape during extrusion. Seals 115 and 117 are 
respectively connected to glass glob storage chute 90 at point 120 and 
extruder bar chamber 100 at point 122. Also, swab paste applicators 124 
are installed on the extrusion rollers 94 and 96 in order to prevent 
surface marring of glass sheet as a result of contact with the metal 
rollers 94 and 96. The paste applied by swab paste applicator 124 is a 
semi-liquid high temperature resistant substance commonly used in the 
glass container industry as a lining between the newly formed glass sheet 
and the metal rollers 94 and 96. The applicators 124, which delivers a 
constant light supply of swab paste to the extruder rollers 94 and 96, 
contact the entire length of these rollers. The swab paste is composed of 
liquid graphite in an inorganic binder, e.g., magnesium silicate, asphalt, 
thermoplastic resin, etc. Examples of trade names for the paste are 
"No-Swab" and "End-O-Swab". 
The swab paste applicators consist of multiple bristles brush (similar to 
the common paint brush) extending 3 or 4 inches from the edge of a metal 
binder. The applicators 124 are 3 to 4 inches in width and no less than 84 
inches in length. The applicator brushes 124 are shown contacting the 
extrusion rolls 94 and 96 in FIG. 6. 
The material composition of the bristles or mats must withstand 
temperatures near 1500.degree. F. without flaking or crumbling which would 
impart a defect into the glass sheet. Graphite fibers and fabrics or 
fiberglass textiles would therefore adequately serve as bristles for the 
paste applicators. 
An accessible container and conduit for continuous paste supply to each 
applicator is viewed in FIG. 6, and labeled as 123 and 125 respectively. 
The section of conduit lying horizontally above and the length of the 
applicators has spaced orifices below of sufficient diameter to allow 
passage of paste for constant saturation of the applicator brushes. 
Conceivably, the viscosity of the paste would be selected to allow gravity 
flow from the containers. 
As shown in FIG. 7, the extruder device 92 employs five compressed air 
operated pistons 128, 130, 132, 134, and 136, respectively housed in 
piston chambers 129, 131, 133, 135, and 137. Pistons 128 and 132 and 136 
generate the extrusion stroke. Accordingly the respective chambers 129, 
133 and 137 of pistons 128, 132 and 136 communicate with a compressed air 
reservoir 140 by means of openings 139 located at the top of these piston 
chambers. Correspondingly, pistons 130 and 134, generate the intake stroke 
of extruder device 92, and the respective piston chambers 131 and 135 
therefore communicate with compressed air reservoir 140 by means of 
openings 141 located at the bottom of piston chambers 131 and 135. 
During the intake stroke of extruder device 92, a conventional valve (not 
shown) is opened, and compressed air enters chambers 131 and 135 via 
openings 141. Compressed air pressure then forces pistons 130 and 134, and 
extrusion bar 98 rigidly attached to these pistons by means of connecting 
rods 143, upwardly. The resultant suction creased by the upward movement 
of extrusion bar causes molten glass to be sucked into the extrusion bar 
chamber 100. 
During the extrusion stroke, a conventional valve (not shown) is opened to 
allow compressed air from reservoir 140 to apply pressure to the top 141 
of pistons 128, 132 and 136. This pressure forces these pistons and the 
extrusion bar rigidly attached to these pistons downwardly, thereby 
resulting in the extrusion of molten glass from extrusion bar chamber 100 
to the glass sheet rollers 94 and 96. During the extrusion stroke, 
compressed air previously forced into intake piston chambers 131 and 135 
is returned to compressed air reservoir 140 for replenishment thereof. 
Likewise, during the intake stroke compressed air previously forced into 
chambers 129, 133 and 137 is also returned to the reservoir 140, thereby 
maintaining the compressed state of the air within the reservoir 140. 
Glass sheet formation is now further described with the air of FIGS. 3, 6 
and 8. Referring to FIG. 6, it is seen that the mobile extruder carriage 
88 is mounted on wheels 142. Extruder carriage wheels 142 mate with tracks 
(not shown) along the length of the molten bath 10. During the extruder 
molten glass intake stroke, the extruder carriage 88 is transported from 
its loading position 145 underneath the basin cylinder 6 to the far end 
144 of the tin bath 10, as shown in FIG. 8. Upon completion of the 
extruder intake stroke, the extruder device 92 commences its extrusion 
stroke during which time the extruder carriage 88 is returned to its 
loading position 145. As the extruder carriage travels from points 144 to 
145 the glass sheet is extruded through rollers 94 and 96 and laid 
directly upon the tin bath 10. 
Referring now to FIGS. 3 and 8, the derivation of compressed air in the 
compressed air reservoir 140 is now described. As seen in these FIGURES, 
air heated in the furnace air cooling passageways 42 is channeled through 
hot air pipes 146 to air compression cylinders 148 via non-reversible 
valves 150. Located within air compression cylinders 148 and travelling 
the length of these cylinders are air compression pistons 152. As the 
extruder device 92 travels from position 145 to position 144, air 
compression pistons 152 likewise move from positions 154 to 156 as shown 
in FIG. 8. During the return of extruder carriage 88 from point 144 to 
point 142, air compression cylinder 148 undergoes its compression cycle as 
piston 152 returns to position 154 from position 156. During the 
compression cycle, non-reversible valves 150 are closed, and a second pair 
of non-reversible valves 151 are opened to admit air to compressed air 
reservoir 140 via pipe 158. As discussed above, the compressed air 
reservoir 140 is the compressed air source for the extruder device 92 
shown in FIG. 6. By using hot air from the electric furnace air-cooling 
passageways 40 as the extruder driving force during the molten glass 
extrusion process, it is assured that the molten glass being extruded 
remains in its molten state. 
As discussed above, the newly formed molten glass sheet, having been 
extruded and compressed by rollers 94 and 96 is laid on the molten tin 
bath 10 during the extrusion stroke of the extruder device 92. The molten 
tin bath 10 is viewed in detail in FIGS. 9b and 10. Electric heating rods 
160 traverse the bath 10 and apply constant melting temperatures to the 
tin contained therein. An external flange 162 forms a lip at the upper 
periphery of the tin bath 10 and provides a narrow flat surface upon which 
the extruded molten glass sheet extends. As shown in FIG. 10, also 
provided around the periphery of the tin bath 10 are marginal strip 
rejection forks 164 which are precisely fitted within recesses contained 
in external flange 162. Rejection forks 164 are pivoted on bars 166 which 
when rotated likewise cause rotation of rejection forks 164. Upon 
completion of the glass cutting step, discussed hereinafter in detail, 
rejection forks 164 are raised vertically as shown in FIG. 10b by the 
rotation of bars 162, thereby returning to cullet scrap glass extruded 
upon external flange 162. 
Returning now to FIG. 9, the glass cutting frame 168 of the present 
invention, and its relationship to tin bath 10 is shown in detail. As seen 
in FIG. 9b, the glass cutting frame 26 is provided with a base flange 170 
which together with the tin bath external flange 162 firmly holds the 
extruded molten sheet when the cutting frame 26 is lowered on the tin bath 
10. In this way, the molten glass sheet is immobilized during the glass 
sheet cutting phase described hereinafter. The two-way glass sheet cutting 
is performed by cutting carriages 172 and 174 which respectively and 
alternately traverse the width and the length of the tin bath 10 during 
the cutting operation. Cutting carriages 172 and 174 are provided with 
two-way cutting tracks 176 and 178, respectively, on the cutting frame. 
Each of the cutting tracks 172 and 174 are provided with upper and lower 
track levels 180 and 182 respectively. Lower cutting track 182 is used 
during the cutting sweep of the cutting carriages, while the upper cutting 
track 180 is used by the cutting carriages during the return travel. In 
this way, the cutting blades, which are lowered for the cutting operation 
as discussed hereinafter, are prevented from dragging through the 
previously cut semi-molten glass sheet during the carriage return sweep. 
Cutting carriages 172 and 174 are raised and lowered from the upper and 
lower cutting track levels 180 and 182 of cutting tracks 172 and 174 by 
conventional means (not shown). Furthermore, as shown in FIG. 9c switches 
184 which are either opto-electrical devices or contact type devices, are 
provided at various points on the cutting tracks 176 and 178. Switches 184 
signal the completion of the cutting sweeps of the cutting carriages 172 
and 174, and initiate the raising and lowering of the cutting carriages 
172 and 184. 
In another possible embodiment, the upper and lower track levels 180 and 
182 can be replaced with a single track level which is raised and/or 
lowered as a cutting carriage begins and/or finishes a traverse of the tin 
bath 10. In this other embodiment, a camming mechanism can be employed to 
actuate the lifting of the single cutting track. 
As seen in FIG. 9a, the cutting carriages 172 and 174 each house a 
plurality of individual cutting block assemblies 186. Each of the cutting 
block assemblies 186 is independently operable, as selected by the 
operator in the control center 24. As presently envisioned, cutting 
carriage 172 is provided with 120 of the cutting block assemblies 186, 
which are arranged in two rows, front and back, 188 and 190 respectively. 
Likewise, cutting carriage 174 is provided with 84 individual cutting 
block assemblies 186, which are arranged in front and back rows 192 and 
194 respectively. As seen in FIG. 9a, an equal number of cutting block 
assemblies 186 are located in the front and back rows of the cutting 
carriages 172. Each cutting block assembly 186 is two inches wide, with 
one inch thereof being occupied by a cutting block 196. Cutting block 
assemblies in the front and back rows 188 and 190 of cutting carriage 182 
are offset one inch with respect to each other as shown in FIG. 12 such 
that for every linear inch of the length of the cutting carriage 172, one 
cutting block 196 is provided. In like fashion, the cutting block 
assemblies 186 of cutting carriage 174 are similarly arranged. As 
discussed below, the one inch separation between adjacent cutting blocks 
196 in the same row of cutting carriages 172 and 174 is necessary to 
provide for the fractional movement to 1/32 of an inch of each cutting 
block 196. 
Referring now to FIGS. 11 and 13, the operation of the cutting block 
assembly 186 is presently described. FIG. 11a is an end view of two 
cutting block assemblies 186 which are respectively located in the front 
and back rows of a cutting carriage 172. Each cutting carriage 172 or 174 
is provided with a pair of shafts 198 and 200 having worm gear segments 
that mesh with gears 202 of each cutting block assembly 186. Worm gear 
shafts 198 and 200 extend the entire length of the cutting carriage 172, 
with shaft 198 being dedicated to the front row of cutting block 
assemblies, and with shaft 200 being dedicated to the rear row of cutting 
block assemblies. 
Each cutting block assembly 186 is also provided with a pair of solenoids 
203 and 204 which respectively control the vertical and fractional 
movement of the cutting block 196. The solenoids 203 and 204 are of 
identical and conventional design, each having an armature 205 which is 
movable upon electrical energization of the solenoid coil (not shown), and 
thus converting electrical impulse into mechanical action. The armature 
205 of the vertical movement solenoid 203 is connected by means of a 
linkage mechanism 206 to an armature linkage pad 207. As discussed 
hereinafter, the vertical movement solenoid 203 in concert with the 
operation of the solenoid armature 205, the armature linkage 206 and the 
armature linkage pad 207 initiate vertical movement of the cutting block 
196. 
Each cutting block assembly 186 is provided with a cutting block cell 208, 
made of thin sheet metal, which houses the cutting block 196 and 
associated cutting block assembly components. These components include a 
threaded gear shaft 209 appending from the gear 202, and a threaded shaft 
sleeve 210 which surrounds and threadedly engages at least a portion of 
the gear shaft 209. Upper and lower sleeve flanges, 211 and 212 
respectively, are provided as an integral part of the shaft sleeve 210, 
with the cutting block 196 retained between the upper and lower flanges 
211 and 212. The upper and lower flanges 211 and 212 respectively are 
provided with a vertical movement gear 213, shown in FIGS. 11a and 11b, 
and a ratchet return gear 214 shown in FIGS. 11a and 11c. Also associated 
with the cutting block cell 208 is the plunger 215, the plunger roller 
216, the plunger contact pad 217, and the plunger expansion spring 218. 
At the outset of a cutting operation, the worm gear shafts 198 and 200 
commence rotation. Therefore, the gears 202 with their companion threaded 
gear shafts 209 likewise commence rotation. The shaft sleeve 210 in 
threaded engagement with the shaft 209 at this time has a "floating" 
association with the shaft 209 and commences rotation in the direction of 
the shaft 209 as long as rotational freedom of the sleeve 210 is 
unimpeded. However, upon selection of a particular cutting block assembly 
186 for service, the associated solenoid 203 is energized, which results 
in movement of the solenoid armature 205, the armature linkage 206, and 
the armature linkage pad 207 from the "released" position (broken line) to 
the "activated" position (solid line) shown in FIG. 11b. Thereupon the 
armature linkage pad 207 contacts the plunger pad 217, and pushes the 
pointed edge 219 of the plunger 215 into engagement with the teeth of the 
vertical movement gear 213, thereby terminating rotational freedom of 
movement of the shaft sleeve 210 on the threaded gear shaft 209. As a 
result, the shaft sleeve 210 proceeds to move up or down on the threaded 
gear shaft 209, depending upon the direction of rotation of the worm gears 
198 or 200. Naturally, as the sleeve 210 descends, so does the cutting 
block 196 which is in effect clasped between the flanges 211 and 212 
attached to the sleeve 210. 
During descent of the cutting block 196, the plunger 215 likewise descends, 
since the plunger 215 is retained in a plunger support 220 attached to the 
cutting block 196. It is noted that the plunger roller 216 connected to 
the plunger 215 by means of the plunger linkage 221 was pushed off a lip 
222 of the cutting block cell 208 under the action of the contact pads 207 
and 217. As the cutting block 196, and therefore the plunger 215 descend, 
the contact pads 207 and 217 disengage, and the roller 216 contacts the 
inner wall of the cutting block cell 208. The plunger 215 is maintained in 
engagement with the vertical movement gear 213 during descent until the 
plunger roller 216 encounters a recess 223 in the walls of the cutting 
block cell 208. Thereupon the expansion spring 218 forces the plunger 
roller 216 into the recess 223, while at the same time forcing 
disengagement of the plunger 215 with the vertical movement gear 213. At 
this time the vertical movement gear 213 and the threaded shaft sleeve 210 
once again resume floating rotation with the threaded gear shaft 209, and 
the cutting block 196 is stopped at the "ON" position. 
Upon completion of the cutting operation, and in the event that no 
fractional movement of the cutting block 196 has occurred, the cutting 
block 196 is returned to its raised "OFF" position by means of the ratchet 
return gear 214, a reversal fin 224, a fin retraction spring 225, and a 
fin stop piece 226, the latter three elements 224, 225 and 226 being 
fixedly mounted on the cutting block cell 208. As is seen in FIG. 11c and 
11d, as the cutting block 196 descends, the ratchet return gear 214 
contacts the reversal fin 224. However in view of the skewed angle of the 
teeth of the ratchet gear 214, and under the force of the retraction 
spring 225, the reversal fin merely pivots to and fro from the fin stop 
226 with no influence on the descent of the cutting block 196. When it is 
desired to return the cutting block to the raised "OFF" position, the 
direction of rotation of the gear shafts 198 and 200 are reversed, thereby 
causing a rotation reversal of the gear 202, the threaded gear shaft 209, 
the shaft sleeve 210, the vertical movement gear 213, and the ratchet 
return gear 214. The reversal fin 224 then engages the teeth of the 
ratchet return gear 214 and terminates the free "floating" rotation of the 
threaded shaft sleeve 210 with the threaded gear shaft 209, thereby 
causing the cutting block 196 to rise within the cutting block cell 208. 
As the cutting block 196 rises, the reversal fin 224, after a short travel 
of the cutting block, disengages with the ratchet return gear 214, but by 
that time the plunger roller 216 has departed from the cell wall recess 
223, thereby causing the plunger 215 to engage the vertical movement gear 
213, thus preventing free rotation of the threaded shaft sleeve 210 on the 
threaded gear shaft 209 and maintaining the ascent of the cutting block 
196. The cutting block 196 therefore continues to rise until the plunger 
roller 216 reaches the cell lip 222 whereupon the plunger expansion spring 
218 forces the roller 216 onto the cell lip 222, and concurrently the 
plunger 215 out of engagement with the vertical movement gear 213. At this 
time the threaded shaft sleeve 210 once again freely rotates with respect 
to the threaded gear shaft 209, ascent of the cutting block 196 ceases, 
and the cutting block 196 has reached its "OFF" position. 
Cutting carriages 172 and 174 are also provided with air conduit 228 
connected to a source of compressed air. This source of compressed air can 
advantageously be the compressed air reservoir 140 discussed above, or 
other wise a conventional source of compressed air. Air conduit 228 runs 
the length of each cutting carriage and is located between the front and 
back rows of cutting block assemblies. Each cutting block assembly is also 
provided with a cutting blade air chamber 234 which is attached to the 
cutting block 196 and which is vertically movable in a cylindrical 
container 235. The base of the container 235 is provided with an access 
opening 230 which communicates with an opening 231 in the air conduit 228. 
The chamber 234 in turn has an air inlet 232 cut into its side at the top 
of the chamber 234. Upon lowering of the cutting block 196 to the "ON" 
position, the chamber 234 is likewise lowered such that the openings 230, 
231 and 232 overlap, thereby providing compressed air cutting power to the 
cutting blade 236 of the particular cutting block 196. Air line 238, which 
is made flexible to permit the lateral fractional cutting block movement 
described hereinafter, is connected to the chamber 234 and channels 
compressed air from the cutting blade air chamber 234 to cutting blade 
propellant fins 240, thereby causing the cutting blade 236 to rotate at a 
rapid speed. 
The fractional movement mechanism 242 of the present invention is now 
described with the air of FIGS. 11a and 13. As mentioned above, the glass 
cutting accuracy of the present invention is to 1/32 of an inch, and 
therefore the fractional movement mechanism is designed accordingly. In 
addition to the cutting block vertical movement worm gear control shafts 
198 and 200, each cutting carriage 172 is also provided with a pair, 244 
and 246, of fractional movement worm gear control shafts, with shaft 246 
being dedicated to the front row and shaft 248 to the back row of the 
cutting block assemblies. Each cutting block 196 is individually embossed 
with a built-in gear 248 at the base of the cutting block 196. Upon the 
lowering of the cutting block 196 to the "ON" position, the embossed gear 
248 meshes with a sleeve gear 250 which rotates freely on its associated 
fractional movement worm gear shaft. Sleeve gear 250 is provided with 
conical openings 252 at either end, and with a bearing section 254 between 
the conical openings 252. Bearing section 254 enables the free rotation of 
the sleeve gear 250 on the fractional movement worm gear shaft. 
Communicating with the conical openings 252 of sleeve gear 250 are 
frictional cones 256 which are laterally movable on the fractional 
movement worm gear shaft and which rotates with this shaft. Also shown in 
FIG. 13 are linkage yokes 258 which are attached to the outside ends of 
the frictional cones 256. Linkage yokes 258 are connected by means of a 
linkage mechanism 260 to the armature 208 of fractional movement solenoid 
204. The armature movement resulting from an energization of solenoid 204 
causes the linkage mechanism 260, supported by linkage rollers 262, to 
apply a lateral force to the linkage yoke 258 in the direction of the 
frictional cone 256, thereby squeezing the cones 256 towards one another. 
As frictional cones 256 travel laterally towards one another, cones 256 
contact the sleeve gear conical openings 252. At this time the sleeve gear 
250, which normally rotates freely on its associated fractional movement 
worm gear shaft 244 or 246, is forced to rotate along with the frictional 
cones 256 as a result of the frictional forces asserted by cones 256 
against the sleeve gear conical openings 252. Since the sleeve gear 250 at 
this point engages the embossed gear 248 at the base of the cutting block 
196, rotation of the sleeve gear 250 induces lateral fractional movement 
of the cutting block 196. It is noted that the slot 261 is provided in one 
side wall of the cutting block 196 to permit clearance of the sleeve 211 
during lateral fractional movement of the cutting block 196. 
Control of the lateral fractional movement of the cutting block 196 is now 
discussed with the aid of FIG. 12. As seen in FIG. 12a, each cutting block 
assembly 186 includes not only the cutting block cell 208, but also a 
dummy cell 264 on which is housed the vertical movement solenoid 203. The 
dummy cell 264 is located adjacent the cutting block cell 208 in the same 
row, front or back, of the associated cutting carriage. The base 266 of 
dummy cell 264 as shown in FIG. 12b is embossed with a plurality of 
contact pairs 272 which are spaced in a saw tooth manner at 1/32 of an 
inch intervals as shown in FIG. 12c. Accordingly, 31 fractional movement 
contact pairs are provided on the base 266 of dummy cell 264. Upon 
selection of a particular fractional movement by the operator in control 
center 34, a voltage is applied across the contact pair 268 associated 
with the particular fractional movement selected. 
Each cutting block 196 is also provided with an electrical current 
conducting contact strip 270. The contact strip 270, is elevated above the 
plunger contact pad 207, and is located at the upper leading edge of 
cutting block 196 as shown in FIGS. 12a and 12b. The contact strip 270 
lightly engages each of the fractional movement contact pairs 268 during 
the fractional movement of the cutting block 196. When the contact strip 
270 engages the particular contact pair 268 associated with the operator 
selected fractional movement, the contact strip 270 short circuits the 
voltage placed across only that contact pair and thereby induces an 
electrical current. This current is then sensed at the control center 24 
which responds by deenergizing the fractional movement solenoid 206 of 
that particular cutting block 196. At this point, the armature 208 of 
solenoid 206 is released, thereby causing the linkage 212 to disengage the 
frictional cones 256 from the conical openings 252 of sleeve gear 250. 
Thereupon sleeve 250 once again freely rotates on its associated shaft 244 
or 246, the fractional movement of cutting block 196 is discontinued, and 
the cutting block 196 comes to rest at the designated fractional movement 
position. As shown in FIG. 12a, the cutting blocks 196 labeled as 271, 
273, and 275 have been lowered to the "ON" position but with no fractional 
movement. Also, the cutting blocks, 196 labeled as 277, 279 and 281 are 
shown in the "ON" position with fractional movement. All other cutting 
blocks 196 are in the "OFF" position. 
As discussed above, the dimensions of the cut glass sheet are determined by 
the particular cutting block assemblies 186 programmed by the operator in 
control center 24. At commencement of the particular program, rotation of 
vertical shafts 198 and 200 and fractional movement shafts 242 and 244 is 
initiated. Thereupon the operator sequentially selects those cutting 
blocks 196 to be lowered to the "ON" position, and the fractional movement 
associated with each of these cutting blocks. These selected cutting 
blocks 196 are then sequentially lowered in accordance with the operator's 
selections. Thereupon the cutting carriage is lowered onto the molten tin 
bath 10 and the molten glass sheet extruded onto the tin bath 10 is cut 
into the prescribed dimensions by alternate passes of the cutting 
carriages 172 and 174. 
In cutting a glass sheet in the semi-molten state while lying upon molten 
tin, the cutting blades 236, rotated by compressed air, penetrate 
completely through the thickness of the glass sheet, thus making it 
unnecessary to separate lites in the cooled rigid state, as is necessary 
when glass is cut by scoring or surface cutting. During cutting carriage 
movement, the lower edge of the cutting blades 236 rotates without damage 
in the molten tin. A reuniting of glass edges after cutting, or "reflow" 
is prevented as the pressure of the glass sheet upon the molten tin causes 
it to exude upward in the wake of the cutting blade path. A separator is 
formed by the molten tin between the edges, though these edges are in 
close proximity. Also, it is noted that the rotating blade 236 tends to 
release portions of the molten tin from its sides to the edges of the 
glass, thereby further preventing "reflow". 
Upon completion of the alternate passes of cutting carriages 172 and 174, 
the glass cutting frame 168 is raised to an elevated position above the 
tin bath 10, whereupon the cut glass sheet is removed from the tin bath 10 
by means of transfer and tempering unit 272, which is discussed in detail 
hereinafter. 
Upon removal of the cut glass sheet, another molten glass sheet is extruded 
over the tin bath 10. If this newly formed molten glass sheet is to be cut 
to the same dimension as the previous glass sheet, than the glass cutting 
frame 168 is merely lowered over the molten tin bath, and the alternate 
passes of cutting carriages 174 and 176 are initiated. However, if the 
newly formed glass sheet is to be cut into a different size, then the 
previously selected cutting block assemblies are reset, in the presently 
described manner, and a new cutting program is initiated. 
The resetting of the cutting block assemblies 186 to the "OFF" position is 
accomplished by re-initiating the rotation of the fractional movement 
shafts 244 and 246. However, in the resetting process, the direction of 
rotation of these worm gear shafts is reversed from the direction of 
rotation employed during the cutting block selection process. After 
initiation of the reversed shaft rotation, each of the previously selected 
fractional movement solenoids 206 are reactivated to engage their 
respective fractional movement mechanisms 242. At this time fractional 
movement linkage mechanism 260 again initiates lateral movement of linkage 
yokes 258, thereby forcing frictional cones 256 into contact with sleeve 
conical openings 252. Thereupon sleeve gear 250 which has remained in 
engagement with embossed gear 248 at the base of cutting block 196, 
commences rotation in the same direction as its associated fractional 
movement shaft 244 or 246, thereby imparting a return lateral movement to 
the cutting block 196. Upon return to the whole inch "On" position, a 
conventional contact switch (not shown) is closed and results in the 
deenergization of fractional movement solenoid 206. At this point the 
reverse rotation of the vertical movement shafts 198 and 200 is initiated, 
thereby causing the ratchet return gear 214 to engage the reversal fin 
224, whereupon ascent of the cutting block 196 to the "OFF" position 
commences in the manner discussed above. 
It is noted that the worm gear shafts 198, 200, 244 and 246 can each be 
fabricated of a single long gear shaft, or these shafts can be constructed 
of a plurality of individual worm gear segments coupled to the end to form 
a single long gear shaft as seen in FIG. 11e. Coupling can be accomplished 
by providing each segment with a square coupling peg 239 at one end of the 
segment, and a mating coupling hole 241 at the other end. Thus, the peg 
239 of one segment mates with the coupling hole 241 of an adjacent 
segment. Segmentized gear shaft segments naturally have their threads, 
coupling pegs, and coupling holes arranged to provide a continuous 
threaded worm gear shaft upon assembly, and facilitate maintanence of the 
cutting carriages 172 and 174 in the event of a failure of one of the 
cutting block assemblies 186. 
As mentioned above, upon completion of the cutting action, glass cutting 
frame 26 is raised and removed from the tin bath. The newly cut glass 
sheet is then removed from the tin bath by means of transfer and tempering 
unit 272, which is viewed in FIG. 14a. Transfer and tempering unit 272 is 
connected to a conventional reversible vacuum source 283 which 
communicates with the transfer and tempering unit 272 through vacuum port 
274. The glass sheet, cut to lite sizes, is lifted by suction from the tin 
bath by the multiple orifices 276 which communicate with a vacuum port 
274. The multiple orifices 276, through which a particle vacuum is applied 
when a sheet transfer place is to be performed, holds the glass sheet 
securely, thereby preventing any lateral movement of the glass sheet that 
might inadvertently cause surface scratching. Furthermore, in anticipation 
of the possibility of glass sheet surface marring by the multiple 
orifices, a smooth absorbent and flexible material with openings to 
accommodate the multiple orifices 276 can be applied to the entire 
undersurface of the transfer unit 272 to provide a protective lining 280 
to protect against glass surface marring. The lining 280 can be made of 
the same material used for the swab paste applicators 174 discussed above. 
Just prior to the commencement of a transfer passage, a mold paste, 
similar to the swab applicator paste discussed above, can be applied to 
the surface of the protective lining 280 to ensure the surface integrity 
of the newly formed glass sheet. 
Transfer unit 272 transports the glass sheet from the molten tin bath 10 to 
either the tempering chamber 12 or the annealing lehr 18, shown in FIG. 1. 
If an annealing phase is scheduled, the glass sheet is tramsported to the 
annealing lehr 18, the partial vacuum existing at orifices 276 is slowly 
released, and the glass sheet is gently lowered to the annealing conveyor 
282 shown in FIG. 2. At the annealing lehr entry point 284 is provided a 
draft shroud 286 which protects against undesirable cross currents of cool 
air which may be detrimental to proper annealing. The annealing conveyor 
282 upon receiving the glass sheet from the transfer unit 272 is activated 
and conveys the glass sheet through the annealing lehr 18, which is 
otherwise of conventional design. During the annealing process, which 
takes approximately 20 to 30 minutes to complete, the glass sheet 
temperature is reduced from approximately 1200.degree. to 1500.degree. F. 
to room temperature. Upon completion of the annealing process, the glass 
lites are subjected to electronic inspection at quality control inspection 
station 20 and then removed to packaging area 22 for further processing. 
If the glass lite is to undergo a tempering phase, transfer and 272 then 
transports the glass sheet from the tin bath 10 to the tempering chamber 
12 shown in FIG. 1. At tempering chamber 12, the glass sheet is gently 
lowered into a tempering chamber conveyor 290. Situated between the belt 
292 of conveyor 290 is the lower tempering unit 294. Lower tempering unit 
284 engages transfer and tempering unit 272 at this point such that they 
completely surround the glass sheet lying on the conveyor belt 292 and 
thereby form the tempering chamber 12. Lower tempering unit 294, like the 
transfer unit 272, is provided with multiple orifices 296 which 
communicate with an air port 298 as shown in FIG. 14a. At this point, the 
orifices 276 of the transfer and tempering unit 272, which were previously 
used to provide the suction by which the glass sheet was lifted from the 
tin bath 10, are instead used to route a stream of cold air from the 
reversible vacuum source to the top surface of the glass sheet. 
Simultaneously, cold air is delivered from a conventional air blower 285 
to the bottom surface of the glass sheet from the orifices 296 in the 
lower tempering unit 294. The simultaneous application of the cold air to 
each surface of the glass, creates a high compression state on these 
surfaces and produces an internal tension within the glass, which remains 
at a high temperature relative to the surfaces of the glass sheet. The 
resulting tempered glass product is relatively scratch resistant, and upon 
breakage, breaks into the small interlocking segments associated with 
safety glass. 
When the initial tempering phase as discussed above is completed, the 
tempering chamber conveyor 290, which also serves as a bed for the glass 
sheet during this initial tempering phase, delivers the sheet to a second 
conveyor 300. The transfer unit 272 disunites with the lower tempering 
unit 294 for the release of the glass sheet to the second tempering 
converyor 300. Conveyor 300 transports the glass lite to the transfer area 
14 shown in FIG. 1 whereupon the conveyor mechanism 300 executes a 
90.degree. turn. The glass sheet then proceeds to the tempering lehr 16, 
and undergoes a second tempering phase in conventional tempering lehr 16. 
Thereafter the glass sheet is removed from the tempering lehr 16 for 
electro-optic inspection at quality control center 20. 
Electro-optic inspection is accomplished by means of a light beam source 
20a and a photocell detector 20b situated at the level of the cut glass 
sheet as it leaves the tempering lehr 16 or the annealing lehr 18 upon 
entering the quality control area 20. (see FIG. 1) Any opaque occlusions, 
caused by impurities, pebbles, ect. break the light beam and indicate a 
fault in one dimension of the glass lite. For all but the highest quality 
glass, unidirectional inspection is adequate. However, if precise fault 
detection is desired, the cut glass lite can be rotated 90.degree. at the 
quality control center 20, and passed by a second pair of electro-optical 
devices, whereupon bidirectional fault isolation is derived. After 
electro-optic inspection the glass lite proceeds to packaging area 22. 
A central control of the entire glass manufacturing process, from the 
intake of raw batch material via the portable furnace intake chute 50 to 
the packaging of the finished glass product at the packaging area 22, is 
provided by means of the centrally located control center 24, as seen in 
FIG. 1. From the central vantage point of control center 24, a minimum of 
personnel have visual access to all points of the glass manufacturing 
operation and, by means of various panel controls, is able to monitor and 
control the glass manufacturing operation. Once such panel control unit 
302 is seen in FIG. 15 to employ a plurality of push button type switches 
304 by which much of the glass manufacturing process is controlled. The 
push button switches 304 are arranged in groups, with each group relating 
to a particular aspect of the glass manufacturing process. For example, 
one group 306 selects those cutting block assemblies 186 in cutting 
carriage 172 to be activated in the particular cutting operation. The 
group of push button switches labeled as 308 in FIG. 15 controls the 
fractional additions to be added to the whole inch of the various cutting 
block assemblies 186 of cutting carriage 172 selected by the push button 
switches in group 306. Likewise, the cutting block assemblies 186 selected 
for cutting carriage 174 and the fractional additions therefor are 
selected by those push button groups labeled as 310 and 312 respectively. 
In selecting a particular glass lite size, a particular cutting block and 
its fraction addition is selected. Thereafter, the remaining cutting block 
assemblies and their respective fractional additions are sequentially 
selected. Pushbutton switch groups 306 and 310 are also provided with 
"START", "RESET" and "STOP" programming controls. 
The "START" puch-button commence rotation of the worm gear shafts 198, 200, 
244 and 246 by which cutting block assemblies 186 are activated, and are 
depressed before the cutting block assembly switches are depressed. The 
"RESET" push-button alternately commences the counter-rotation of shafts 
198, 200, 244 and 246 by which the cutting blocks 196 are returned to 
their "OFF" position 224. The "STOP" pushbutton enables the operator to 
correct a mistake in selection of a cutting block assembly, or a 
malfunction in either cutter carriage 172, or 174. Upon depressing a 
"STOP" button, shafts 198, 200, 244 and 246 commence counter-rotation. 
Thereafter, those cutting block assemblies selected are returned to the 
"OFF" position. 
Glass lite thickness and strength is selected by the switches in the group 
labeled as 314. The switches of group 314 govern not only the quantity of 
molten glass deposited into the extruder chamber 100, but also the 
separation distance between extruder glass sheet rollers 94 and 96, since 
glass thickness is governed by both of these factors. Nine switches are 
provided for the nine thicknesses ranging from this 0.035 inches to the 
thickest setting of 0.250 inch. For each of the 9 thickness selections, 
the quantity of molten glass deposited into the extruder chamber is 
governed by the number of clockwise revolutions of the basin cylinders 6. 
For example, the quantity of molten glass needed to extrude the thin sheet 
of 0.035 inches would require 3 revolutions of the basin cylinder. 
Therefore to progress to each of the other 8 strength settings, an 
additional revolution for each thickness would be necessary, or as 
follows: 
______________________________________ 
Strength Basin Cylinder Revolutions 
______________________________________ 
.035" 3 
.050" 4 
.065" 5 
.080" 6 
.095" 7 
.125" 8 
.187" 9 
.219" 10 
.250" 11 
______________________________________ 
Also, the number of cycles a particular glass lite size is to be produced 
is governed by the pushbutton switches contained in group 316. For 
example, if 158 glass sheet extrusions and cuttings of the same lite sizes 
are required, then the pushbutton switches 1, 5, and 8, of the lines A, B, 
and C, respectively of group 16 would be selected. Furthermore, by 
selecting glass sheet thickness and the total number of cycles, a 
calculation is automatically made by computing circuits within the control 
center, to deliver the prescribed amount of raw glass batch to the furnace 
intake. This amount of raw batch material delivered to the furnace is 
continually updated in accordance with the glass requirements programmed 
at panel control unit 302. 
Panel control unit 302 is also provided with a BEGIN pushbutton switch by 
which the glass sheet cutting process is initialted upon the completion of 
the lite size programming sequence described above. An emergency stop 
button is also provided so that the entire glass manufacturing process can 
be halted at any time within the discretion of the operator located in the 
control center 24. 
In view of the above discussion, it is believed that the inventive features 
attendant to the present invention address a number of shortcomings found 
in the prior art. For example, the air cooling passageway 42 surrounding 
the vertical furnace 2 and the transverse refiner 4 provide a low exterior 
temperature of the refractory brick lining 34 which forms the inner wall 
of the furnace and the refiner sections, while concurrently leaving the 
furnace interior temperatures unaffected because of the 10 to 16 inch 
thickness of the refractory brick lining. This air cooling feature tends 
to diminish high temperature pockets, especially at the electrodes, and 
therefore tends to evenly distribute heat within the furnace. The design 
of the electrode cartridge, and in particular the insulator lining 48, 
further reduces localized heating effects. As a result, not only are 
temperature gradients diminished and a more homogenous glass product 
formed, but also the service life of the furnace walls is increased, 
thereby decreasing maintenance requirements. Furthermore, in view of the 
fact that molten glass is withdrawn from the base of the vertical furnace 
2, the dependence of the generation and maintenance of convection currents 
within the molten galss is minimized, thereby assuring a more homogenous 
glass melt. 
The design of the basin cylinders 6 and their relationship to the 
transverse refiner 4 represents a significant advance in the art of 
metering glass charges. Not only does the basin cylinders 6 precisely 
meter glass to the extruder device, but it also enhances the glass melt 
homogeneity within the transverse refiner as a result of the incidental 
glass mixing effect produced by the revolutions of the basin cylinders. 
Also, the balanced design of the two basin cylinders employed, i.e., one 
basin cylinder 6 at each end of the transverse refiner, promotes a thermal 
symmetry within the refiner which additionally contributes to a homogenous 
glass melt. Also, the transverse refiner glass level control produced by 
the refiner float 76 and the cut-off mechanism 66 maintain a constant 
transverse refiner glass level 72 which assures a uniform metering of 
molten glass by the basin cylinder 6. 
Likewise, the extruder mechanism 8, including the eccentrically pivoted 
extruder rollers 94 and 96, provides a highly reliable technique by which 
glass sheet of a particular thickness and strength is reproduced. Extruder 
operation powered by compressed hot air maintains the extruder temperature 
at a sufficiently high level such that the glass melt is easily maintained 
in its molten state, thereby assuring the feasibility of the applying 
extruding techniques to the glass sheet forming process. 
The advantages of the glass cutting apparatus of the present invention are 
manifold. As a result of the multiple cutting block assemblies 186 housed 
by the cutting carriage assemblies 172 and 174, the glass sheet can be cut 
with a degree of automation and precision virtually unknown heretofore. 
Also, by cutting the newly formed glass sheet while it still remains on 
the molten tin bath 10, it becomes possible to dispense with the glass 
sheet scoring step which is extensively used in the prior art. Elimination 
of this scoring step decreases glass breakage, and furthermore hastens the 
glass manufacturing process. Also, energy is conserved, because it is no 
longer necessary to reheat a newly cut glass sheet in order to put this 
glass sheet in the proper thermal state for subsequent tempering 
treatment. 
The transfer and tempering unit 272 of the present invention advantageously 
provides a technique by which the newly cut semi-molten glass heat can be 
transferred to a tempering chamber, while nevertheless maintaining this 
glass sheet in its flat condition. Furthermore, the dual utilization of 
the transfer and tempering unit 272, as both a "transfer" and a 
"tempering" unit, by changing the direction of air flow through the vacuum 
port 274, decreases system complexity and optimizes plant space 
utilization, while improving the overall efficiency of the operation. 
Additionally, the design of the electrode cartridge assembly 44 with it 
cartridge lock-in doors 50, lock-in latchs 51, and casing cut off 52 
enables speedy on-line electrode replacement without the necessity of 
furnace shut down. Obviously, this on-line replacement feature enhances 
overall system productivity, while substantially reducing system 
maintenance costs. 
Obviously, numerous modifications and variations of the present invention 
are possible in light of the above teachings. It is therefore to be 
understood that within the scope of the appended claims, the invention may 
be practiced otherwise than as specifically described herein.