Note: Descriptions are shown in the official language in which they were submitted.
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SHAPING GLASS SHEETS USING MOLDS OF DIFFERENT SHAPES
Background of the Invention
1. Field of the Invention
This invention relates to shaping and cooling glass sheets and
particularly to the high speed production of bent glass sheets that are
toughened by air quenching, and most particularly, for shaping and heat
treating relatively thin glass sheets.
Shaped glass sheets are widely used as side windows in vehicles
such as automobiles or the like and, to be suitable for such application,
flat glass sheets must be shaped to precisely defined curvatures dictated
by the shape and outline of the frames defining the window openings into
which the glass side windows are installed. ~t is also important that the
side windows meet stringent optical requirements and that the windows be
free of optical defects that would tend to interfere with the clear viewing
therethrough in their viewing area. During fabrication, glass sheets
intended for use as shaped windows in vehicles are subjected to thermal
~reatment to temper the glass for strengthening the same and increasing the
resistance of the shaped window to damage resulting from impact. In
addition to increasing the resistance of a glass sheet to breakage, temper-
ing also causes a glass shèet to fracture into relatively small, relatively
smoothly surfaced fragments that are less injurious than the relatively
large, jagged fragments that result from the more frequent breakage of
untempered glass.
The commercial production of shaped glass sheets for such pur-
poses commonly includes heating flat sheets to the softening point of the
glass, shaping the heated sheets to a desired curvature and then cooling
the bent sheets in a controlled manner to a temperature below the annealing
range of the glass. During such treatment, a glass sheet is conveyed along
a substantially horizontal path that extends through a tunnel-type furnace
where the glass sheet is one of a series of sheets that are heated to the
deformation temperature of glass and into a shaping station where each
glass sheet in turn is transferred onto a lifting member that lifts the
glass sheet into engagement with a vacuum mold. The vacuum mold holds the
shaped glass by suction while the lifting member retracts to below the
substantially horizontal path. At sbout the same time, a transfer and
tempering ring having an outline shape conforming to that of the glass
sheet slightly inboard of its perimeter moves upstream into a position
below the vacuum mold and above the lifting member. Release of the vacuum
deposits the shaped glass sheet onto the tempering ring.
In prior art apparatus, the lifting member, the vacuum mold and
the transfer and tempering ring had shaping surfaces whose curvature
conformed to one another. Hence, when production required a change of
production pattern from sheets of one elevational shape and one outline
configuration to sheets of a different elevational shape and/or a different
outline configuration, it was believed necessary to remove and replace all
three glass sheet engaging members, namely, the lifting member, the vacuum
mold and the transfer ring.
2. The Prior Art
. _
~ .S. Patent No. 1,889,881 to Ralph C. Thompson shapes a soft,
horizontally disposed glass sheet between an upper mold and a lower mold of
complementary shape. A portion of the lower mold within its outline
-- 2 --
S3
marginal portion is recessed below the surface of the outline marginal
portion to avoid simultaneous engagement of the opposite glass sheet
surfaces in the vision area of the glass sheet. The soft glass sheet is
simultaneously engaged at its opposite surfaces in the marginal portion
only and sags within the limits of the recessed lower mold portion inside
the marginal portion.
~ .S. Patent ~o. 3,508,903 to Samuel L. Seymour press bends tong
gripped glass sheets between molds having shaping surfases of slightly
different radii of curvature to avoid simultaneous engagement of the
viewing area between the molds. Such an arrangement does not avoid tong
marks in the bent glass.
U.S. Patent No. 3,607,187 to Harold A. McMaster lifts a soft,
flat glass sheet by suction a~ainst a dowl~ward facing shaping surface of a
vacuum mold to shape the sheet by suction thereagainst. Much power is
needed to provide the suction necessary to shape the entire flat glass
sheet to conform to the shape of the vacuum mold in incremental portions,
particularly those portions most widely spaced from the vacuum mold when
other portions are initially engaged by the vacuum mold.
U.S. Patent No. 3,846,104 to Samuel L. Seymour provides method
and apparatus in which glass sheets are conveyed through a furnace on
conveyo-; means, and heated while passing through the furnace to a tempera-
ture approaching the glass softening point. At a shaping station beyond
the furnace, each glass sheet in turn is lifted by a lower outline shaping
mold which raises the glass sheet into engagement ~ith an upper vacuum mold
having a shape conforming to that desired for the glass. The upper vacuum
mold remains at the shaping station and holds the shaped glass thereagainst
as the lower shaping mold ratracts to below the level of the conveyor
53
means. A tempering ring shaped to support the bent glass sheet adjacent
it8 marginal or peripheral edge only, moves generally horizontally between
the shaping station and a cooling station to receive each shaped glass
sheet released by the vacuum mold and trànsfer it to the cooling station.
The outline shapes of the lower outline shaping mold and of the tempering
ring conform to the shape of the downward facing shaping surface of the
upper vacuum mold. The molds and the ring were believed to require replace-
ment whenever a production pattern was changed.
U.S. Patent No. 4,092,141 to Robert G. Frank and DeWitt W.
Lampman provides similar apparatus by providing vertically movable sheet
transfer means for rapidly removin~ from the tempering ring each bent glass
sheet after the latter has had its surfaces hardened sufficiently to permit
it to be conveyed on an additional downstream conveyor providing a glass
sheet supporting surface at an elevation slightly higher than the level at
which the glass sheet is supported by the transfer and tempering ring.
~owever, the apparatus of this patent also requires that the lifting mold,
the upper vacuum mold and the trans~er and tempering ring define the same
shape and that all be replaced to accommodate for a different production
pattern.
The prior art patents fail to provide a shaping operation that
permits a single lower shaping mold and a single upper vacuum mold to be
installed permanently to provide means to produce a plurality of shapes of
different outline patterns and of different curvatures. It would be
desirable to reduce the number of parts of glass sheet shaping apparatus
that must be changed when production requires a change in pattern from one
part having a different severity of bend from that of the previous produc-
tion part.
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Summary of the Invention
The present invention provides shaping apparatus that helps to
produce glass sheets of different outlines and different curvatures using a
common lower shaping mold and a common upper vacuum mold in combination
with a relatively readily replaceable ring-like member having an outline
shaping surface that conforms to the shape desired for the glass sheet both
in elevation and in plan outline.
The apparatus aspect of the present invention comprises the
subcombination of a lower mold having an upwardly facing shaping surface
defir~ing a shape having a given sharpness of bend and an upper vacuum mold
having a downwardly facing shaping surface defining a shape having a bend
component of slightly more shallow curvature. Means is provided to vary
the distance between the upper and lower molds to bring the glass sheet
close enough to the upper mold to enable the latter to enga~e the glass
sheet by suction. Means is provided to increase the space between the
molds to permit the entry of a ring-like member therebetween. The ring-
like member combines with the subcombination to provide a specific embodi-
ment of apparatus and definPs a shape that may be the same or different
from that of the downwardly facing shaping surface of the upper vacuum
shaping mold.
According to the present invention, in its broadest terms, a
heat-softened glass sheet at the shaping station is engaged at its lower
surface with a lower mold having an upward facing shaping surface defin-
ing a bend component having a given sharpness of curvature. The soft glass
sheet sags by gravity toward the upward facing shaping surface of the lower
mold. The upper vacuum mold provided above the lower mold engages the
marginal portion only of the glass sheet initially, and then increases its
s~
area of engagement as suction continues to change the shape of the heat-
softened glass sheet to that of the downwardly facing shaping surface of
the upper vacuum mold. If no further shaping is required for the glass
sheet, it may be released from the vacuum mold.
However, glass sheets shaped in the manner described are usually
heat-strengthened or tempered to improve their strength and are usually
supported on a ring-like member adjacent their periphery while the shaped
glass sheet is cooled by playing tempering medium (most frequently, blasts
of cold air) that chill the opposite surfaces of the shaped glass sheet
rapidly enough to establish a stress pattern throughout the glass sheet
thickness that characterizes heat-strengthened or tempered glass. When the
ultimate shape desired for the glass sheet is that of the downwardly facing
shaping surface of the upper vacuum mold, the ring-like member has an
upwardly facing outline shaping surface that conforms to that of the
downwardly facing shaping surface of the upper vacuum shaping mold.
However, when a given combination of lower mold and upper vacuum
mold of slightly different configurations is provided at a glass sheet
shaping apparatus and the glass part to be produced requires a shape
different from that defined by the downwardly facing shaping surface of the
upper vacuum mold, according to the present invention, it is possible to
produce a wide variety of bends without changing the lower mold or the
upper vacuum mold. All that is needed is to replace the ring-like member
whose upper shaping surface correlates with the previous production part
with one whose upper shaping surface correlates with the next succeeding
production part.
In a specific embodiment of this invention, the lower mold is
provided with an upper shaping surface of cylindrical configuration about a
353
given axis of bending having a given radius of curvature, the upper vacuum
mold has a downwardly facing shaping surface of cylindrical configuration
about an axis parallel to said given axis and having a larger radius of
curvature. The ring-like member has a shaping rail that includes a trans-
verse rail portion defining a cylindrical bend about an axis parallel to
said given axis whose radius of curvature may be within a large range of
radii. If the ultimate bend desired is cylindricalJ the ring-like member
has a pair of longitudinal shaping rail portions that extend in the general
direction of said given axis with straight upper shaping surfaces. For
shaping a glass sheet to a compound bend, the latter pair of shaping rail
portions have upper shaping surfaces that are shaped in elevation to
conform to the shape desired for the glass sheet transverse to its first
component of bend, which may be cylindrical or any other desired configura-
tion.
Apparatus conforming to the present invention has been used to
produce shaped glass sheets having different outlines and shapes having
radii of curvature ranging from 43 inches (lO9 cm~ to 60 inches (152 cm)
without changing the lower mold or the upper vacuum mold of the glass sheet
shaping apparatus. Such production has been performed using a permanently
installed lower mold whose upwardly facing shaping surface defines a shape
having a radius of curvature of 48 inches (122 cm~, a permanently installed
upper vacuum mold whose downwardly facing shaping surface defines a shape
having a radius of curvature of 50 inches (127 cm) and replaceable ring-like
members defining different degrees of curvature within the limits desired.
The present invention will be better understood in the light of a
description of an illustrative embodiment that follo~s, which description
includes the accompanying drawings whereîn like reference numbers refer to
like structural elements
5~
Brief Description of the Drawings
FIG. 1 is a fragmentary, plan view of apparatus for shaping and
tempering glass sheets incorporating a preferred embodiment of the present
invention, with certain parts omitted for clarity;
:: FIG. 2 is a fragmentary, longitudinal view of the embodiment of
FIG. 1 with certain parts omitted or broken away or shown in inconsistent
positions to show other parts of the apparatus more clearly and with
: certain positions depicted in phantom consistent with FIG. l;
FIG. 3 is a schematic perspective view of a portion of the
apparatus of FIGS. 1 and 2 with parts omitted to show a simplified struc-
ture of a shaping station included in the preferred embodiment;
FIG. 4 is a cross-sectional, scbematic view taken across the
shaping station showing a flat, hot glass sheet entering the shaping
station with the upper vacuum mold and the lower mold separated from one
another;
FIG. 5 is a view similar to FIG. 4 taken immediately thereafter,
showing how the hot glass sheet is engaged by the upper shaping surface of
the lower mold to shape the glass sheet;
FIG. 6 is a view similar to FIGS. 4 and 5, taken immediately
- after FIG. 5, showing how the upper vacuum mold initially engages the glass
sheet when the distance between the molds is suff~ciently small to enable
suction to lift the glass sheet from the lower mold;
FIG. 7 is a view taken shortly &fter that of FIG. 6, showing how
continued suction increases the area of engagement between the glass sheet
and the upper vacuum mold;
FIG. 8 is a view taken shortly after FIG. 7, showing the lower
mold and upper vscuum mold separated and a ring-like member whose upper
-- 8 --
surface defines a transverse shape having a larger radius of curvature than
that of the upper vacuum mold receiving the glass sheet from the upper
vacuum mold, and depicting the difference in transverse shape between the
glass sheet and the upper transverse curvature of the ring-like member at
the moment the glass sheet makes initial contact with the ring-like member;
FIG. 9 is a view of the ring-like member and its supported glass
sheet taken shortly after FIG. 8, showing how the glass sheet conforms to
the shape of the ring-like member after a brief interval of support thereon;
FIG. 10 is a view similar to that of FIG. 8, showing a glass
sheet at the moment it is deposited onto a ring-like member whose upper
shaping surface defines a shape having a smaller radius of curvature than
that of the downwardly facing shaping surface of the vacuum mold;
FIG. 11 is a view similar to FIG. 9 showing how the ring-like
member supports the shaped glass sheet after a brief interval of support
thereon;
FIG. 12 is an elevational view of a portion of a longitudinal
side rail portion of a ring-like member having a transverse rail portion of
cylindrical concave elevation wherein the longitudinal side rail portion
has a straight upper edge for supporting a glass sheet shaped to a cylin-
drical shape;
FIG. 13 is a view similar to that of FIG. 12 of a longitudinal
rail portion of another embodiment, showing how the longitudinal rail
portion of the ring-like member of this embodiment has its upper edge
shaped longitudinally in concave elevation to help produce a compound bend
of concave elevation about two axes of bending in a glass sheet;
FIG. 14 is a view similar to that of FIGS. 12 and 13 of a longi-
tudinal rail portion of another embodiment, showing how the longitudinal
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rail portion of the ring-like member of this embodiment has its upper edge
shaped longitudinally in convex elevation to help the ring-like member
produce a complicated shape in the glass sheet that comprises a cylindrical
bend of concave elevation conforming to the transverse rail portion about
one axis of bending and a convexly shaped elevational curve conforming to
the longitudinal side rail portion about another axis of bending; and
FIG. 15 is a view similar to FIGS. 12, 13 and 14 of a longitu-
dinal rail portion of still another embodiment, showing how the longitu-
dinal rail porti~n of this embodiment is shaped with both convex and
concave elevational portions to help shape a glass sheet into a complicated
curvature that includes a cylindrical shape of concave elevation conforming
to the upper edge of the transverse rail portion about one axis and a
complicated bend comprising convexly and concavely curved portions conform-
ing to the upper edge of the longitudinal rail portion.
Description of the Preferred Embodiment
Referring now to FIGS. 1 and 2 of the drawings, an apparatus for
heating and shaping sheets of material, such as glass, includes a heating
means including a furnace 12 through which sheets of glass are conveyed
from a loading station (not shown) while being heated to the glass deforma-
tion temperature. A cooling station generally indicated at 14 for cooling
the curved sheets of glass and an unloading station (not shown) beyond the
cooling station 14 are located in end-to-end relation to the right of the
furnace 12. An intermediate or shaping station 16 is disposed between the
furnace 12 and the cooling station 14. A sheat transfer means 17 located
in the cooling station 14 transfers the shaped and tempered glass sheet to
a downstream conveyor 20 for transport to the unloading station.
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9S3
~ eat may be supplied in the furnace 12 by hot gases from gas
burners or by electrical radiant heaters or by a combination of both, which
heat supply means are well known in the art. The heating means includes a
horizontal conveyor comprising longitudinally spaced, transversely extend-
ing conveyor rolls 18 that define a path of travel which extends through
the furnace 12 and the shaping station 16. The rolls of the conveyor are
arranged in sections and their rotational speed controlled through clutches
(not shown) so that the speed of the different conveyor sections may be
controlled and synchronized in a manner well known in the art. A glass
sensing element S is located beyond the exit of furnace 12 to initiate a
cycle of operation of this apparatus.
Limit switches LS-l through LS-5 are provided to synchronize the
operation of various elements of the apparatus according to a predetermined
sequence. The glass sensing element S, the limit switches LS-l through
LS-5 and various timer circuits actuated thereby cooperate to provide
synchronizing means for the apparatus of the present specification.
The shaping station 16 comprises a lower mold 34 and an upper
vacuum mold 36. The latter is composed of metal covered with a refractory
material such as fiber glass 35, as is well known in the art. The former
comprises an upper surface 22 (FIG. 3) conforming in elevational shape to
a first shape desired for a glass sheet to be bent. The upper surface 22
is interrupted intermittently by transversely extending grooves 24 which
provide clearance for raising and lowering the lower mold 34 between a
recessed position below the conveyor rolls 18, as depicted in FIGS. 3, 4
and 8 to 11, and an upper position above the level of said conveyor rolls,
as depicted in FIG. 5. The lower mold 34 is fixed to a lower mold sup-
port 26 and is limited in its upward movement toward the upper vacuum
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mold 36 to a closest spacing therebetween slightly greater than the glass
sheet thickness, preferably no less than twice the glass sheet thicXness.
Since automobile side windows have a fairly constant radius of
curvature about a horizontal axis in order to facilitate their raising and
lowering in an automobile body between an open and a closed position, many
different patterns in a family of patterns have different outline shapes
but are bent to the same radius of curvature. Therefore, it is desirable
to have one lower mold capable of producing each family of patterns. It
has been found that a lower shaping mold of a given radius of curvature
having longer dimensions than a family of side windows of said given radius
of curvature but of different outline shapes and/or different dimensions
can fabricate curved side windows of said family of different sizes but of
said given radius of curvature. In the apparatus of this specification,
one lower shaping mold can be installed in conjunction with an upper vacuum
mold of slightly different curvature to produce any pattern of a family of
patterns having a given radius of curvature but of different si2es and/or
outline shapes without requiring any removal or replacement of the lower
mold and/or of the upper vacuum mold.
The upper surface 22 of the lower mold 34 is preferably smoothly
surfaced to avoid imparting any irregularity in the supported glass sheet
surface, is composed of a material that does not react with glass, is
easily shaped to the smoothly surfaced contour desired and has good dura-
bility despite intermittent contact with hot glass that causes rapid
cyclical temperature variations over an extended period. A good material
for the grooved lower shaping mold 34 is an alumino-silica cement sold by
Johns-Manville under the trademark of TRANSITE.
Raising and lowering means in the form of a piston 28 rigidly
mounted to a piston support platform 30 raises and lowers support 26 and
its attached lower shaping mold 34 a limited distance. Alignment posts 32
are attached to mold support 26 to assure vertical movement of the lower
mold 34. A lug 33 is connected to mold 34 to actuate limi~ switch LS-4.
The upper vacuum mold 36 has an upper mounting plate 37 and a
lower wall 38 that is apertured, as well as side walls 39, at least one of
the latter being apertured. The lower wall 38 is shaped to be less sharply
bent than the shaping surface formed by the upper surface 22 of the lower
mold 34. The upper vacuum mold 36 communicates with a source of vacuum
(not shown) through an evacuation pipe 40 and a suitable valve (not shown).
The upper vacuum mold 36 is suitably connected through upper vertical guide
rods 41 to an upper supporting frame 42 and movable relatively thereto by
an upper vertical piston 43. The evacuation pipe 40 may be connected
through a suitable valve arrangement to a source of pressurized air (not
shown) and the valves for the vacuum line and for the pressure line may be
synchronized according to a predetermined time cycle in a manner well known
in the art.
Any portion of a side wall 39 of the upper vacuum shaping mold 36
that contains apertures is also provided with an apertured slide 60 having
a tab 61 at one end thereof. The slide 60 has its longitudinal side
portions engaged by a pair of parallel Z-shaped guides 62. The latter are
attached along their length to the side wall 39. The tab 61 can move
between the Z-shaped guides 62 when the position of the apertured slide 60
is adjusted relative to the apertured side wall 39. The apertured slide 60
has apertures 63 corresponding in size, shape and space therebetween to the
arrangement of the apertures in apertured wall 390
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When the apertured slide 60 occupies a position in which its
apertures 63 are completely aligned with the apertures in apertured side
wall 39, it provides a maximum effective open area for the side wall 39.
When the apertured slide 60 occupies a position in which the apertures 63
face the spaces between the apertures in the side wall 39, side wall 39 has
no effective open area. It is understood that the slide 60 may be adjusted
in any position in which its apertures 63 are partially aligned wit~ aper-
tures in the side w211 39 or in which only one or more of its apertures 63
are partially or completely aligned with one or more apertures in the side
wall to provide a des;red amount of effective open area in the side wall 39
and means for adjusting the amount of open &rea as needed.
The reason for providing apertures in at least one of the side
walls 39 and an apertured slide 60 therefor is to insure that a glass
sheet G drops uniformly onto a ring-like member 70 without tilting from the
orientation at which it is engaged against the apertured lower wall 39 of
upper vacuum shaping mold 36 when vacuum is released from the latter. When
small apertures are uniformly distributed throughout the apertured lower
wall 38 and the glass sheets treated have a uniform outline shape, such as
an essentially rectangular or circular outline, air under pressure acts
uniformly around the perimeter of the glass sheet to cause the latter to
drop without tilting onto the ring-like member 70 when vacuum is released
in upper vacuum mold 36. However, when a treated glass sheet has an
irregular outline, upon releasing the vacuum, air enters the vacuum chamber
of the upper vacuum mold 36 through the small apertures in such a manner as
to cause a temporary pressure gradient within the upper vacuum mold 36.
This pressure gradient produces a non-uniform downward thrust against the
upper surface of the glass sheet that was previously supported against the
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53
apertured lower wall by vacuum. This non-uniform downward thrust causes
the released glass sheet to tilt as it drops toward the ring-like member 70.
Providing additional apertures having an effective open area that can be
adjusted for the upper vacuum mold provides relatively rapid inflow of air
into the upper vacuum shaping mold that masks the effect of the relatively
910w flow of air through the relatively small apertures in the apertured
bottcm wall 38 to cause the glass sheet to tilt as it drops toward the
ring-like member 70.
The relative size of the total effective open area due to the
positions of the apertures 63 relative to the side wall 39 compared to the
total area of the apertures in the apertur~d bottom wall 38 determines the
effectiveness of the apertured slide 60 and apertures in apertured side
wall 39 to overcome the tilting tendency. Other factors involved in deter-
mining the amount of effective open area of apertures 63 relative to the
total area of the apertures of apertured wall 38 that are exposed when the
apertured wall 38 engages a glass sheet that is required to insure a non-
tilting transfer of the glass sheet from the upper vacuum shaping mold 36
to the ring-like member 70 include the area, thickness and irregularity of
outline shape of the glass sheet pattern being treated.
Increasing the effective open area of aligned apertures 63 reduces
the chances of tilting the disengaged glass sheet en route to the ring-like
member 70 when the vacuum is released on the upper vacuum shaping mold 36
for any particular glass sheet pattern. However, if the effective open
area is made too great, suction apparatus consuming a great amount of
energy is required. In the interest of energy conservation, the effective
open area of the aligned openings is made as small as possible consistent
with the open area necessary to insure a glass sheet transfer without
~ilting.
s~
The apertures in the apertured lower wall 3~ are made as small as
possible and are spaced as closely as is necessary to assure vacuum support
for 3 hot glass sheet with reasonable energy consumption. For an upper
vacuum mold having a glass sheet engaging apertured lower wall 38 with
dimensions 46 inches (117 cm) long and 22 inches (56 cm) wide, apertures
having a diameter of .09 inches ~0.23 cm) and spaced apart from one another
1.5 inches (3.8 cm) in a rectangular or diamond pattern have been found to
work adequately in handling glass sheets whose weight is up to 20 pounds
(9 Kgm.). Five apertures, each having a diameter of one inch ~25.4 mm)
spaced apart on 2.2 inch (56 mm) centers are sufficient for the apertured
slide 60 and the corresponding row of apertures in side wall 39.
The shaping station 16 also includes a lower platform 44.
Vertical posts 46 interconnect the cornerel of the upper mold supporting
frame 42, the piston support platform 30 and the lower platform 44 to
provide a unitary structure. Wheels 48 are mounted on the unitary struc- -
ture to permit the shaping station 16 to be readily removed frnm a position
of alignment between the exit of the furnace 12 and the entrace to the
cooling station 14 and an offset position to facilitate maintenance of the
structural elements of the shaping station 16.
The cooling station 14 comprises an upper plenum 51 provided with
longitudinally spaced transverse rows of transversely spaced pipe nozzles 52
extending downward to direct air applied under pressure to the upper plenum
toward the upper surface of a glass sheet that is aligned with the bottom
openings of the nozzles. Opposing the upper plenum 51 is a lower plenum 53
provided with lower bar-type nozzle housings 54 disposed with thick walls
extending vertically and having elongated openings 55 directed upward
through their thickness so that air applied under pressure to the lower
53
plenum 53 is directed through the elongated openings 55 upward against the
lower major surface of the glass sheet. The openings of the lower bar-type
nozzle housings oppose corresponding openings in the upper pipe nozzles.
The bar-type nozzle housings are spaced vertically below the upper pipe
nozzles to provide clearance for moving the ring-like member 70 along a
path between said upper nozzles and said lower nozzles. The lower ends of
the rows of pipes are located along a curved surface complementary to the
curved shape of the upper smooth surfaces of the bar-type housings for the
lower nozzles to provide a curved clearance space therebetween conforming
to the transverse shape of the glass sheets conveyed therebetween. If
desired~ the plenums 51 and 53 may be sectionalized along the length of
cooling station 14 to provide different air pressures into the various
sections of the upper plenum and of the lower plenum 60 as to provide a
program of air blasts along the length of the cooling station 14.
The upper surfaces of the lower bar-type nozzle housings 54 are
smoothly surfaced and parallel to one another to provide discontinuous
smooth surfaces on which glass cullet is deposited when a glass sheet
fractures in the cooling station 14. The lower bar-type nozzle housings 54
are interconnected by a pivotally mounted frame 50 that pivots about an
axis extending longitudinally of the length of the cooling station 14.
Fra=e pivoting means 49 is provided to pivot the frame 50, thereby pivoting
the smoothly surfaced lower bar-type nozzle housings 54 into an oblique
orientation that permits the glass fragments to slide to one side of the
cooling station to clear the cooling station of glass fragments rapidly and
efficiently. The lower bar~type nozzle housings 54 are returned to
their normal position after the fragments of a prior glass sheet have slid
to one side of the cooling station and before the next glass sheet is
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53
proces~ed. The means to pivot the lower bar-type noz~les 54 is similar in
construction to that disclosed and claimed in U.S. Patent No. 3,846J106 ~o
Samuel L. Seymour for pivoting a lower set of nozzles.
The spaces between the upper pipe nozzles 52 provide paths for
the escape of air blasted against the upper concsve surface of glass sheets
treated by the apparatus de~cribed in ~his specification. me sp~ces
between adjacent lower bar-type nozzle hou6iDgs 54 provide paths for he
escape of air blasted against the lower convex surface of said glas~ -
sheet6. ~hile more total space is provided for the escape path~ above the
glass than for ~he escape paths below the glass, the difference in total
space for e~cape provided on opposite sides of ehe shaped glass sheets is
helpful in providing greater uniformity of cooling of the top and bottom
surfaces than would be the case if both upper aod lower glass sheet Aur-
faces had escape paths of equal size. This result follows becau6e a
convex surface is more streamlined than a concaYe surface. Therefore, it
is morP difficult to remove ~ir applied normally against a concave surface
than air applied normally sgainst a convex surface and therefore ~ore
escape space i~ provided to remove air blasts that impinge ~gain~t the
upper concave surface than for air blAs~s that impinge against the lower
convex surface.
The sheet transfer means 17 at the cooling station 14 includes a
vertically movable ~onveyor section comprising a set of doughnut rolls 56 of
relatively large diameter mounted on the central portion3 of thin ~hafts 58
driven from a gear bo~ and a motor (not shown) mounted on a frame 64. A
lug 65 connected to frame 64 actuates limit s~itch LS-5. Elevator means 66
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s~
in the form of one or more pistons is rigidly supported (each with a piston
rod 68) on said frame. Vertical guides 69 control movement of the frame 64
in such a manner that when piston rods 68 are extended, the set of doughnut
rolls 56 is lifted in unison in a vertical direction into positions where
their common upper tangential plane lies in a horizontal plane above the
uppermost portion of the shaping surface of the ring-like member 70 to
transfer a glass sheet therefrom.
The cooling station 14 also comprises a downstream conveyor 20
comprising additional conveyor shafts 72 downstream of the sheet transfer
means 17. Each additional conveyor shaft 72 is provided with a pair of
additional doughnut rolls 74 fixed thereto for rotation therewith. The
shafts 72 are longitudinally spaced from one another along the length of
the downstream conveyor 20 and the additional doughnut rolls 74 are rigidly
supported with their common upper tangent occupying a horizontal plane
slightly above the uppermost surface of ring-like member 70.
The ring-like member 70 comprises a rail that extends in the form
of a ring-like structure disposed edgewise with its width forming the
height of the rail. The rail comprises a transversely extending rail
portion 76 at the upstream end of the ring-like member, a pair of longi-
tudinaIly extending rail portions 77 that extend in a downstream direction
from the transversely extending rail portion 76 and a pair of inturned
downstream end rail portions 78. Connectors 79 are attached at their inner
ends to the laterally outer surface of the rail at æpaced points therealong
and at their outer ends to a reinforcing frame 80. Both the latter and the
frame-like member 70 are shaped in outline similar to the outline shape of
a supported glass sheet and in elevation similar to the curvature of the
supported glass sheet.
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, .,
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The reinforcing frame 80 i9 preferably constructed of an outer
sLeel pipe similar in outline shape to that of the ring-like member 70 and
surrounds the latter in spaced relation thereto. The space between the
r;ng-like member 70 and the reinforcing frame 80 is determined by the
length of the connector means 79. Both the ring-like member 70 and the
reinforcing frame 80 have open portions at their downstream ends.
The reinforcing frame 80 is connected to a carriage 96 through con-
necting members 97. The carriage 96 is provided with upstanding ears 98 that
terminate in internally threaded sleeves 100 that engage a worm drive 102 on
each side of the carriage 96. This arrangement guides the movement of the
ring-like member 70 between an upstream position at shaping station 16, a
downstream position in alignment with sheet transfer means 17 and an inter-
mediate parking position just downstream of the shaping station. The
carriage 96 is reinforced by several arcuate cross braces (not shown)
shaped to conform with the transverse curved shape defined by the upper
surfaces of the lower bar-type nozzle housings 54 and the lower ends of the
rows of upper pipe nozzles 52 so as to be capable of moving therebetween.
The doughnut rolls 56 of the shaped glass sheet transfer means 17
are arranged in spaced, parallel rows. At their upper positions, the verti-
cally movable rolls 56 have an upper common tangent in the same horizontal
plane as the upper common tangent of the additional doughnut rolls 74. At
their lower positions, rolls 56 are located below the path taken by ring-
like member 70 and its supporting frame 80.
The worm drive 102 controls the position of the carriage 96 and
its supported ring-like member 70 relative to one of the three positions o
rest occupied by the ring-like member 70 during a cycle of operation.
Limit swit~hes LS-l, LS-2 and LS-3 are provided for actuation by a lug 104
attached to the carriage 96 to control different steps in a cycle of move-
ment of the ring-like member 70 to be explained subsequently.
- 20 -
A Cycle of Operation
At the beginning of a shaping cycle according to the present
invention3 a glass sheet G is conveyed into the glass shaping station 16 on
conveyor rolls 18 with the lower mold 34 disposed in a retracted position
with its upward facing shaping surface entirely below ehe upper support
surface provided by the conveyor rolls 18 and the upper vacuum mold 36
having its apertured downward facing shaping surface 38 spaced a short
distance above the upper surface of the glass sheet G. The latter travels
from a position between the sensing elements S for a sufficient time for it
to be in the proper position of alignment between the lower mold 34 and the
upper vacuum mold 36. S;nce the glass sheet is initially shaped to a
cylindrical curve about an axis extending substantially parallel to the
direction of glass sheet movement defined by the conveyor rolls 18, the
exact moment that the lower mold 34 is actuated is not as critical as it
would be for more complicated bends.
As the glass sheet arrives at the shaping station 16, a piston 28
is extended thereby permieting lug 33 to disengage from limit switch LS-4.
This causes vacuum to be applied to the upper vacuum mold 36 as the lower
mold 34 is lifted. The glass sheet is shown in ~IG. 5 being lifted on the
lower mold 34 into a position in the vicinity of the upper vacuum mold 36.
Since the glass sheet is hot when it arrives at the shaping station, it
readily sags by gravity to conform to the relatively sharp curvature of the
upwardly facing shaping surface of the lower mold 34 by the time it arrives
in position in close adjacency to the downward facing shaping surface of
the upper vacuum mold 36. Glass sheet G i9 lifted into close adjacency to
the upper vacuum mold 36 by limiting the extent of upward movement of
piston 28, and before the glass sheet is simultaneously engaged between the
~5~3iS~
upward facing surface of the lower mold 34 and the downward facing shaping
surface of the upper vacuum mold 36, suction lifts the shaped glass sheet G
so that the peripheral portion only of the glass is initially brought into
engagement with the downward facing shaping surface of the upper vacuum
mold 36. The shape defined by the downward facing shaping surface of
the upper vacuum mold 36 is of a shallower bend than the upward facing
shaping surface of the lower mold 34. This arrangement permits the glass
sheet G to be initially supported against the downward facing shaping
surface of the upper vacuum mold 36 in the position depicted in FIG. 6 with
the portion of the glass sheet intermediate ies end portions initially out
of contact with the downward facing shaping surface of tha upper vacuum
mold 36.
Lower mold 34 has been lifted in response to the sensor S actuat-
ing a timer circuit (not shown) that extends the piston 28 on sensing the
passage of the glass sheet G into the ~haping station 16. Limit switch LS-4
is released by the onset of lifting of mold 34 to actuate the vacuum for
the upper vacuum mold 36 as previously described, also actuates a timer
that controls ~he onset of the return of the lower shaping mold to its
recessed position. The latter timer is timed to insure that the return of
the lower mold 34 by retraction of piston ~8 is coordinated with the time
that the glass sheet is engaged by suction against the downward facing
shaping surface of the upper vacuum mold 36. The timer also initiates the
upward retraction of vertical piston 43 which causes lifting of the upper
vacuum mold 36 simultaneous with the downward movement of the lower mold 34.
Vacuum is continued as the upper vacuum mold rises so as to cause the upper
surface of the glass sheet to conform exactly to the more shallow shape of
the downward facing shaping surface of the upper vacuum mold 36. This
stage of the operation is depicted in FIG. 7.
When the upper vacuum mold 36 reaches the upper position depicted
in FIG. 8, the shaping station is now ready to receive the ring-like mem-
ber 70 into position between the upper vacuum mold 36 and the lower mold 34.
When lug 104 on carriage 96 engages limit switch LS-l, the ring-like
member 70 is stopped at its aforesaid upstream position directly below the
upper vacuum mold 36. At the same time, when the ring-like member 70
occupies itæ upstream position immediately below the upper vacuum mold 36,
limit switch LS-l releases the vacuum in upper vacuum mold 36, thereby
permitting the shaped glass sheet to be deposited onto the ring-like mem-
ber 70. The shape of the ring-like member transverse to the path of
movement, and particularly the transversely extending portion 76 of the
ring-like member 70 may have the same curvature or a different curvature
from that defined by the downwardly facin~, shaping surface of ~he upper
vacuum mold 36. In FIG. 8, a ring-like me~mber 70 is shown having a shaping
surface that is more shallow than that defined by the upper vacuum mold 36.
Under these circumstances, the glass sheet, still soft from its heating in
the furnace 12, is dropped so that its center portion initially rests on
the center portion of the transversely extending rail portion 76 of the
ring-like member and the extremities of the glass sheet initially bent to a
sharper curvature are spaced upward from the shaping rail transverse
portion as depicted in FIG. 8. ~owever, before the carriage 96 moves the
glass sheet into the cooling station 14, its end portions sag to conform to
the remainder of the outline configuration of the shaping rail of the
ring-like member 70.
FIG. 10 is similar to FIG. 8 only showing a glass sheet G being
dropped onto a ring-like member 70 whose transversely extending rail
portion 76 defines a curvature. of even sharper radius of bend than that
- 23 -
s~
)
defined by the downward facing shaping surface of the upper vacuum mold 36.
The radius of curvature may even be sharper than that defined by the lower
mold 3~. Thus, when the glass sheet G is dropped on the termination of
vacuum, only the side edges of the bent glass sheet will initially rest on
the transversely extending rail portion 76 of the ring-like member 70 and
the glass will then sag to complete its sharper shape in conformance with
the upper edge of the transversely extending rail portion 76 of the ring-
like member 70 as depicted in FIG. 11.
The glass sheet G supported on the ring-like member 70 is trans-
ferred to the cooling station 14 where air under pressure is applied
through the downward facing noz~les 52 extending from the upper plenum
chamber 51 and through the orifices of the lower bar-type nozzles 54
extending upward from the lower plenum chamber 53 to cool the glass as
rap;dly as possible to impart at least a partial temper thereto. When the
glass sheet reaches a pos;tion above the doughnut rolls 56, the latter are
raised in unison to lift the glass sheet G off the ring like member 70
while rotating in unison in a direction that propels the glass sheet in a
downstream direction onto the downstream conveyor 20.
FIG. 3 shows the cooled glass sheet G transferring from the
doughnut rolls 56 of the sheet transfer means 17 in a downstream direction
depicted by the arrow d while the ring-like member 70 is simultaneously
beginning to return in an upstream direction depicted by the arrow u toward
the intermediate parking position immediately downstream of the shaping
station 16 in case the succeeding glass sheet G has not as yet been engaged
by suction by the upper vacuum shaping mold 36. The ring-like member 70
may move into a parking position depicted in FIG. 2 immediately downstream
of the shaping station 16 or directly into its upstream position ~t the
- 24 -
S3
-
shaping station 16 should the glass sheet be already supported by suction
against the upper vacuum mold 36 and the lower mold 34 has moved down to a
vertical position sufficiently low to provide clearance for the ring-like
member 70 to move to below the vacuum mold 36 without stopping.
When the glass sheet supported on the ring-like member 70 arrives
in a position above the sheet transfer means 17, the doughnut rolls 56 and
their thin shafts 58 are in their downward retracted position with frame 64
being retracted downwardly by the retraction of piston rod 68 actuated by
elevator means 66 while awaiting the arrival of the ring-like member 70
into position where lug 104 engages limit switch LS-2. The worm drive 102
has driven the carriage 96 and its supported ring-like member 70 part way
into the sheet transfer means 17. A timer circuit actuated by lug 104
engaging limit switch LS-2 in the downstream direction has caused the ele-
vator means 66 to raise the piston 68, th~ereby lifting frame 64, shafts 58
and rotating doughnut rolls 56 into intermediate positions approaching the
level at which they would lift the glass sheet G off the ring-like member.
This upward movement releases limit switch LS-5, thereby causing the
doughnut rolls 56 to start to rotate in unison.
When the ring-like member 70 arrives at its most downstream
position, lug 104 engages limit switch LS-3 to stop the worm drive 102. At
this time, the rotating doughnut rolls 56 have begun to transfer the glass
sheet over the ring-like member 70 toward the most upstream doughnut roll
74 of the downstream conveyor 20. The piston rod 68 remains fully extended
as the glass sheet G continues to move downstream further into the downstream
conveyor 20. At a proper time, a timer actuated by limit switch LS-3 con- -
trols the onset of the reverse rotation of the worm drive 102 that controls
the return movement of the ring-like member 70 in an upstream direction to
~. -
s~
either the parking position or directly into the shaping station. An addi-
tional timer controlled by limit switch LS-3 causes the elevator means 66 to
start to retract the piston rods 68, thereby lowering the doughnut rolls 56
and their thin shafts 58 to prepare the transfer means 17 for the next
operation. If the apparatus operates rapidly enough, as indicated by the
time out of a timer circuit whose time starts by a subsequent actuation of
the sensing means S, the reset limit switch LS-4 permits the ring-like mem-
ber 70 to move directly upstream through the parking position into the
shaping station 16 without stopping at its parking position. During the
time that the ring-like member 70 moves into or through the parking posi-
tion controlled by the engagement of lug 104 against limit switch LS-2,
lower mold 34 remains retracted below the conveyor rolls 18 to provide
clearance for a succeeding glass sheet G Ito enter into a position of
alignment between the upper vacuum mold 36 and the lower mold 34.
The shaping rail of the ring-like member 70 may be provided with
longitudinally extending rail portions 77 that are curved either concavely
or convexly in elevation (as depicted in FIGS. 13 and 14, respectively) or
curved both ways (as seen in FIG. 15) in combination with the transverse
rail portion 76 that is curved in elevation to define compound shaping
surfaces. If the longitudinally extending portions 77 of the rail bave an
upper shaping surface that is straight as shown in FIG. 12, then the
ring-like member defines a cylindrical curvature whose radius of curvature
defined by the transversely extending rail portion 76 may be the same or
different from that defined by the downward facing shaping surface of the
upper vacuum mold 36. It is also understood that the transversely extend- -
ing rail portion 76 may define a shaping surface portion whose shape is any
shape desired other than cylindrical.
- 26 -
5~
According to a specific embodiment of the present invention, a
combination of a lower mold having an upward facing shaping surface of a
relatively sharp bend, such as a 48 inch radius of curvature, has been
combined with an upper vacuum mold having a downward facing shaping surface
defining a cylindrical bend of 50 inch radius of curvature to provide
cylindrical bends in a glass sheet by drop forming the glass sheet bent to
a cylindrical radius of curvature of 50 inches onto readily replaceable
ring-like members defining radii of curvature from less than 43 inches to
greater than 60 inches. In addition, cylindrical bends formed by suction
against the upper shaping surface have been converted into compound curva~ -
tures by drop forming the hot glass sheet from the upper vacuum mold onto
ring-like members whose longitudinal shaping rail portions are shaped to
conform to the shape desired for the other component of bending about an
axis extending transverse to the path of movement whereas a cylindrical or
other component of bend is formed about an axis of bending longitudinal to
the path of movement.
It is understood that any type of complicated bend defined by the
rail-like member including complicated bends having both convex and concave
elements in elevation in the direction of glass sheet movement may be
combined with any transverse radius of curvature within a wide range of
limits.
According to a preferred embodiment of the present invention,
therefore, a permanently installed lower mold 34 having an upward facing
shaping surface of cylindrical configuration cooperates with a permanently
installed upper vacuum mold having a downward facing shaping surface of a
larger radius of curvature of cylindrical configuration in combination to
form a bend having a shape conforming to that of the downward facing
- 27 -
53
shaping surface of the upper vacuum mold. However, if further shaping is
desired, then the shape of the ring-like member defines a different shape
correlated with the ultimate shape desired for the glass sheet. Therefore,
the present invention does not require any replacement of either the lower
mold or the upper vacuum mold. It is only necessary to change the ring- -
like member whenever a change in production pattern calling for shaping a
glass sheet to a different outline or a different configuration which could
be either a cylindrical bend or a more complicated bend incorporating a
cylindrical bend having a radius of curvature over a relatively wide range
of curvatures or a non-cylindrical bend component is required.
The form of the invention shown and described in this disclosure
represents an ilLustrative preferred embodiment and various modifications
thereof. It is understood that various changes may be made in the struc-
ture and method of operation without departing from the gist oE the inven-
tion except insofar as defined in the claimed subject matter that follows.
- 28 -
