METHOD, STATION AND SYSTEM FOR PRESS FORMING GLASS SHEETS
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for forming glass sheets, to a press
station for forming glass sheets, and to a press forming system for forming glass
sheets.
2. Background Art
Glass sheets can be press formed, which also is sometimes referred to
as being press bent, after being heated sufficiently to permit such forming. This
forming can be with curvature that has straight line elements as have cylindrical or
conical shapes. Actually, in the press forming industry, conical glass sheets having
the straight line elements are referred to as cylindrical curvature just like those with
actual cylindrical shapes having the straight line elements. As disclosed in United
States patents 6,543,255 Bennett et al. and 6,578,383 Bennett et al., the entire
disclosures of which are hereby incorporated by reference, glass sheets heated within
a heating chamber to a sufficiently high temperature for forming can be roll formed
by inclined rolls and then conveyed to a press station for press forming to a final
shape. The press forming can be so as to maintain the straight line elements or to
provide curvature to the straight line elements so that the glass sheet is formed in
transverse directions, which in the glass industry is referred to as being formed with
"cross bend" or "cross curvature."
SUMMARY OF THE INVENTION
One object of the present invention is to provide an improved method
for forming glass sheets.
In carrying out the above object, the method for forming glass sheets
is performed by initially forming a heated flat glass sheet to an upwardly concave
curved shape with upper end portions and a lower intermediate portion extending
between the upper end portions, with the upper end portions and intermediate portion
having straight line elements, and with the glass sheet curved transversely to the
straight line elements. The initially formed glass sheet is located below an upper mold
having a downwardly facing surface with downwardly convex curvature along
transverse directions. The end portions of the glass sheet are moved upwardly relative
to the intermediate portion to initially contact the end portions of the glass sheet with
the downwardly facing surface of the upper mold to form the straight line elements of
the end portions with curvature while the intermediate portion of the glass sheet still
has its straight line elements without any significant curvature. Thereafter, the
intermediate portion of the glass sheet is moved upwardly relative to its end portions
to contact the intermediate portion of the glass sheet with the downwardly facing
surface of the upper mold to also form the straight line elements of the intermediate
portion with curvature so the entire glass sheet is curved along transverse directions.
The glass sheet can be initially formed with a generally cylindrical
shape that has the straight line elements or can be initially formed with a conical shape
that has the straight line elements.
As disclosed, the straight line elements of the end portions of the glass
sheet are formed with curvature against the upper mold before the intermediate
portion contacts the upper mold.
It is also possible for the end portions of the glass sheet to be pressed
against the downwardly facing surface of the upper mold with a predetermined force
that is subsequently reduced to facilitate movement of the end portions of the glass
sheet along the downwardly facing surface of the upper mold as the intermediate
portion of the glass sheet continues to move upwardly for forming against the
downwardly facing surface of the upper mold.
The heated flat glass sheet as disclosed is initially formed within a
heating chamber on a conveyor by inclined rolls of progressively increasing
inclination along a direction of conveyance and is then conveyed out of the heating
chamber to a press station at which the upper mold is located.
The initially formed glass sheet is disclosed as being lifted upwardly
off of the conveyor in the press station by a lower ring that is moved upwardly from
below the glass sheet and has: (a) end portions spaced laterally from each other
relative to the direction of conveyance with upwardly concave curved shapes along the
direction of conveyance, and (b) intermediate portions spaced from each other along
the direction of conveyance with upwardly concave curved shapes extending
transversely to the direction of conveyance between the end portions of the lower ring.
After the lower ring lifts the glass sheet upwardly off the conveyor, the end portions
of the lower ring are moved upwardly relative to the intermediate portions of the lower
ring to contact and form the end portions of the glass sheet against the downwardly
facing surface of the upper mold while the intermediate portion of the glass sheet is
still located below the downwardly facing surface of the upper mold, and after the end
portions of the lower ring form the end portions of the glass sheet against the
downwardly facing surface of the upper mold, the intermediate portions of the lower
ring are moved upwardly to contact and form the intermediate portion of the glass
sheet with the downwardly facing surface of the upper mold to complete the press
forming.
Furthermore, the end portions of the glass sheet are disclosed as each
being initially pressed against the downwardly facing surface of the upper mold by the
end portions of the lower ring with a predetermined force that can be subsequently
reduced to facilitate movement of the end portions of the glass sheet along the
downwardly facing surface of the upper mold as the intermediate portion of the glass
sheet continues to be moved upwardly by the intermediate portions of the lower ring
into contact for forming against the downwardly facing surface of the upper mold.
Another object of the present invention is to provide an improved glass
sheet press station.
In carrying out the immediately preceding object, the glass sheet press
station includes a conveyor for conveying along a direction of conveyance a heated
and initially formed glass sheet having an upwardly concave shape including upper
end portions spaced laterally from each other with respect to the direction of
conveyance and a lower intermediate portion that extends transversely with respect to
the direction of conveyance between the end portions, with the upper end portions and
the lower intermediate portion having straight line elements, and with the glass sheet
curved transversely to the straight line elements. The press station includes a lower
ring over which the glass sheet is conveyed. The lower ring has end portions spaced
laterally from each other relative to the direction of conveyance with upwardly
concave curved shapes along the direction of conveyance, and the lower ring also has
intermediate portions spaced from each other along the direction of conveyance with
upwardly concave curved shapes extending transversely to the direction of conveyance
between the end portions of the lower ring. The end portions and the intermediate
portions of the lower ring are movable vertically together with each other and
independently of each other. An upper mold of the press station is located above the
lower ring and has a downwardly facing surface with downwardly convex curvature
both along and transverse to the direction of conveyance in complementary
relationship to the curvature of the end portions and intermediate portions of the lower
ring. An actuator of the press station: initially moves the end portions and the
intermediate portions of the lower ring upwardly together with each other to lift the
initially formed glass sheet upwardly off of the conveyor; then moves the end portions
of the lower ring upwardly relative to the intermediate portions of the lower ring to
move the end portions of the glass sheet upwardly into contact with the downwardly
facing surface of the upper mold to provide curvature to the straight line elements of
the end portions of the glass sheet while the intermediate portion of the glass sheet has
not yet been formed by the upper mold; and thereafter moves the intermediate portions
of the lower ring upwardly relative to its end portions to contact and form the
intermediate portion of the glass sheet against the downwardly facing surface of the
upper mold to provide curvature to the straight line elements of the intermediate
portion of the glass sheet so the entire glass sheet has curvature in transverse
directions.
The lower ring of the press station is disclosed as including a support
frame on which the intermediate portions of the lower ring are mounted for
movement with the support frame, and a pair of connections that respectively mount
the end portions of the lower ring on the support frame for vertical movement with
respect thereto and with respect to the intermediate portions of the lower ring. The
pair of connections are shown as including pivotal arms having first ends that are
pivotally mounted on the support frame and second ends that respectively mount the
end portions of the lower ring.
The actuator of the press station is disclosed as including cylinders for
applying upward force to the end portions of the lower ring so as to move upwardly
relative to the intermediate portions of the lower ring to provide the movement of the
end portions of the glass sheet upwardly into contact with the downwardly facing
surface of the upper mold to provide forming thereof along the direction of
conveyance while the intermediate portion of the glass sheet has not yet been formed
by the upper mold. Furthermore, the actuator may operate the cylinders to reduce the
upward force applied to the end portions of the lower ring as the intermediate portions
of the lower ring are moved upwardly relative to the end portions of the lower ring to
facilitate movement of the glass sheet end portions relative to the downwardly facing
surface of the upper mold as the intermediate portions of the lower ring move the
intermediate portion of the glass sheet into contact with the downwardly facing
surface of the upper mold to provide the forming thereof along the direction of
conveyance. In addition, the lower ring is disclosed as including adjusters for
adjusting the positions of its end portions and intermediate portions relative to each
other.
Another object of the present invention is to provide an improved glass
sheet press forming system.
In carrying out the immediately preceding object, the glass sheet press
forming system includes a conveyor for conveying glass sheets along a direction of
conveyance and a furnace having a heating chamber through which the conveyor
conveys glass sheets from an entrance end of the furnace toward an exit end thereof
for heating in preparation for forming. Adjacent its exit end the furnace includes
inclined rolls of progressively increasing inclination along the direction of conveyance
so as to initially form each glass sheet with an upwardly concave curved shape
extending transversely with respect to the direction of conveyance with upper end
portions and a lower intermediate portion extending between the end portions, with
the upper end portions and the lower intermediate portion having straight line
elements, and with the glass sheet curved transversely to the straight line elements.
The system includes a press station to which the conveyor conveys the initial formed
glass sheet at a location downstream from the exit end of the furnace. The press
station includes a lower ring over which the glass sheet is conveyed. The lower ring
includes end portions spaced laterally from each other relative to the direction of
conveyance with upwardly concave curved shapes along the direction of conveyance,
and the lower ring includes intermediate portions spaced from each other along the
direction of conveyance with upwardly concave curved shapes extending transversely
to the direction of conveyance between the end portions of the lower ring. The end
portions and the intermediate portions of the lower ring are movable vertically
together with each other and independently of each other. The press station also
includes an upper mold located above the lower ring and having a downwardly facing
surface with convex curvature both along and transverse to the direction of
conveyance in complementary relationship to the curvature of the end portions and
intermediate portions of the lower ring. An actuator of the press station: initially
moves the end portions and the intermediate portions of the lower ring upwardly
together with each other to lift the initially formed glass sheet upwardly off of the
conveyor; then moves the end portions of the lower ring upwardly relative to the
intermediate portions of the lower ring to move the end portions of the glass sheet
upwardly into contact with the downwardly facing surface of the upper mold to
provide curvature to the straight line elements of the end portions of the glass sheet
while the intermediate portion of the glass sheet is still below the upper mold; and
thereafter moves the intermediate portions of the lower ring upwardly relative to its
end portions to contact the intermediate portion of the glass sheet with the
downwardly facing surface of the upper mold to provide curvature to the straight line
elements of the intermediate portion of the glass sheet so the entire glass sheet has
curvature in transverse directions.
The objects, features and advantages of the present invention are
readily apparent from the following detailed description of the preferred embodiment
when taken in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGURE 1 is a schematic side elevation view of a glass sheet press
forming system that includes a press station whose operation performs forming of
glass sheets in transverse directions.
FIGURE 2 is a schematic cross sectional view through the system taken
along the direction of line 2-2 in Figure 1 at an exit end of a furnace of the system and
illustrates horizontal and inclined rolls on which heated glass sheets are conveyed for
initial roll forming prior to exiting the furnace in preparation for press forming.
FIGURE 3 is a schematic cross sectional view taken through the system
along line 3-3 in Figure 1 at its press station to illustrate the construction of a lower
ring and an upper press mold that are movable between the solid and phantom line
indicated positions to press bend the initially roll formed glass sheet.
FIGURE 4 is a perspective view illustrating wheel conveyor assemblies
of the conveyor that convey the initially formed glass sheet to above the lower ring of
the press station for the press forming.
FIGURE 5 is a side elevational view of the upper mold taken in the
same direction as Figure 1 to illustrate its downwardly facing surface against which
the final forming takes place.
FIGURE 6 is a perspective view of the upper mold turned upside down
to illustrate the curvature of the downwardly facing mold surface in transverse
directions both along and transverse to the direction of conveyance.
FIGURE 7 is a perspective view of the lower ring.
FIGURE 8 is a top plan view of the lower ring.
FIGURE 9 is an elevational view of the lower ring taken along the
direction of line 9-9 in Figure 8, which is in the direction of conveyance, but with
portions of the lower ring removed to illustrate its left and right end portions as being
at the same elevation as left and right ends of intermediate portions of the lower ring
which is the positioning involved during initial and final processing at the press
station.
FIGURE 10 is a view similar to Figure 9 but shows the lower ring with
its right and left end portions raised with respect to the right and left ends of the
intermediate portions of the lower ring which is positioning involved during an
intermediate portion of the press forming operation.
FIGURE 11 is a schematic view at the press station taken along the
direction of conveyance and showing the manner in which the wheel conveyor
assemblies convey the glass sheet into the press station above the lower ring and
below the upper mold.
FIGURE 1 is a schematic view similar to Figure 11but taken at a later
stage after the lower ring has moved upwardly to lift the initially formed glass sheet
upwardly off the conveyor into proximity with the downwardly facing surface of the
upper mold.
FIGURE 13 is a schematic view similar to Figure 12 but at a still later
stage of the press bending cycle after end portions of the lower ring have lifted end
portions of the initially formed glass sheet upwardly into contact with the downwardly
facing surface of the upper mold.
FIGURE 14 is a schematic view similar to Figure 13 but at a later stage
after the intermediate portions of the lower ring have been moved upwardly to contact
the intermediate portion of the glass sheet with the downwardly facing surface of the
upper mold to complete the press forming of the glass sheet in transverse directions
both along and transverse to the direction of conveyance.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference to Figure 1 of the drawings, a system for press forming
glass sheets is generally indicated by 10 and includes a press forming station 1 whose
construction and method of operation will be described in an integrated manner with
the entire system to facilitate an understanding of different aspects of the system.
With continuing reference to Figure 1, the system 10 includes a furnace
14 having a roll forming station 16 just upstream along a direction of conveyance C
from the press bending station 12. Downstream from the press forming station 12
along the direction of conveyance C, the system 10 is illustrated as including a final
processing station 18 at which the formed glass sheet can be slowly cooled for
annealing or more rapidly cooled by quenching to provide heat strengthening or
tempering.
As illustrated by continuing reference to Figure 1, the furnace 14 has
entry and exit ends 20 and 22 and includes a heating chamber 24 (Figure 2) having a
conveyor 26 for conveying glass sheets along the direction of conveyance through the
furnace from the entry end to the exit end. The conveyor 26 on which the glass sheets
are heated can be either a conventional gas hearth or a roll conveyor on which the
glass sheets are conveyed during heating from ambient temperature to a sufficiently
high temperature to permit forming, i.e., also referred to as bending in the glass sheet
industry.
The furnace exit end 22 includes the roll forming station 16 which is
illustrated in Figure 2 as having horizontally extending conveyor rolls 28 that are
rotatively driven and spaced horizontally within the heating chamber along the
direction of conveyance extending laterally with respect thereto to support and convey
the heated glass sheets. The roll forming station 16 also includes a pair of sets 30 of
bending rolls 32, with the bending roll sets 30 spaced laterally with respect to each
other within the heating chamber 24 along the direction of conveyance. Each set of
bending rolls 30 is supported and rotatively driven by a drive mechanism 33 with the
bending rolls at progressively increasing inclinations along the direction of
conveyance as illustrated by reference numerals 32a, 32b, 32c and 32d in Figure 2. The
conveyance of each heated glass sheet G along the direction of conveyance in
cooperation with the bending rolls 32 provides initial forming of the glass sheet G
along a direction transverse to the direction of conveyance as illustrated in Figure 2.
This forming provides the glass sheet with straight line element that may be parallel
to each other in a cylindrical shape or angled with respect to each other in a conical
shape. As each location of the glass sheet along the direction of conveyance is bent
from its flat shape, this bending also further bends the preceding location such that the
net effect is a slightly conical shape.
With combined reference to Figures 1 and 3, the press forming station
12 as previously mentioned is located externally of the furnace 14 downstream from
its exit end 22 to receive the initially formed glass sheets from the roll forming station
16. More specifically, the press forming station 12 includes a lower wheel bed 34 of
the conveyor for receiving an initially formed glass sheet to be further press formed
by press forming apparatus collectively indicated by 36. The lower wheel bed 34
includes a lower base structure 38 and a plurality of conveyor wheel assemblies 40.
Each wheel assembly 40 as is hereinafter more fully described includes a housing
having an upper end including a wheel 44 and having a lower end including a
detachable connection 46 for detachably connecting the wheel assembly to the support
38. A drive mechanism provides rotational driving of the wheel 44 of each wheel
assembly 40 upon connection thereof to the support 38. For a more detailed
description of the conveyor and the drive mechanism, refer to United States patent
6,543,255 which has previously been incorporated by reference. Also, it should be
noted that the conveyor instead of having only wheel conveyor assemblies can also
have elongated roller conveyor assemblies both horizontally and inclined as disclosed
by United States patent application Serial No. 12/756,521 filed on April 8, 2010 by
Nitschke et al. under the title Press Bending Station And Method For Bending Heated
Glass Sheets, the entire disclosure of which is hereby incorporated by reference.
As illustrated in Figure 3, a lower press ring support frame 50 of the
press forming apparatus 36 supports a lower press ring 52 that has an upwardly
concave shape and is received within the wheel bed 34 below the wheels 44 of the
wheel conveyor assemblies 40 in a ring shape thereof where no wheel assemblies are
located. The construction of the lower press ring is hereinafter more fully described.
As illustrated in Figure 3, an upper mount 56 of the press station 12 supports an upper
press mold 58 of the press forming apparatus 36. This upper press mold 58 has a
downwardly facing convex forming face 60 complementary to the upwardly concave
shape 54 of the lower press ring 52.
An actuator collectively indicated by 62 in Figure 3 provides relative
vertical movement between the lower press ring 52 and the wheel bed 34 and between
the lower press ring and the upper press mold 58 to move the heated glass sheet above
the wheel bed and ultimately into pressing engagement between the lower press ring
and the upper press mold to press form the glass sheet as is hereinafter more fully
described. As disclosed, the actuator not only moves the lower press ring 52 upwardly
but also moves the upper press mold 58 downwardly so as to more rapidly decrease
the spacing between the lower press ring and the upper mold and thereby reduces the
cycle time. However, it is possible to only move the lower press ring 52 upwardly to
perform the pressing operation but with a longer cycle time.
The press forming station 12 as illustrated by Figure 3 and described
above has the wheel bed 34 provided with an upwardly curved shape in a direction
transverse to the direction of conveyance along which the wheel bed receives the
heated glass sheet corresponding to the initially formed shape provided by the roll
forming station 16 illustrated in Figures 1 and 2. More specifically, the lower base
structure 38 of the wheel bed 34 includes a plurality of rails 64 that extend along the
direction of conveyance and have different elevations, as provided by schematically
indicated adjusters 65 as shown in Figure 3, along a direction transverse to the
direction of conveyance to provide the curved shape of the wheel bed.
With reference to Figures 5 and 6, the upper press mold 58 has its
forming face 60 provided with an array of holes 6 1 at which a vacuum is provided
from a vacuum source 66 shown in Figure 1 so as to support the formed glass sheet
after the press forming and ensure forming of the glass sheet to the shape of the
forming face. Upon downward movement of the lower press ring 52 and upward
movement of the upper press mold 58 provided by actuator 62, a shuttle 68 of the final
processing station 18 is moved by an actuator 70 to move a delivery ring 72 toward
the left below the upper mold 58. Termination of the vacuum provided by the vacuum
source 66 may then be accompanied by the supply of pressurized gas to the upper
mold surface 60 to release the glass sheet onto the delivery ring 72 and the shuttle
actuator 70 then moves the shuttle 68 back toward the right to the position illustrated
such that the delivery ring 72 and the formed glass sheet thereon are delivered for final
processing such as slow cooling for annealing or more rapid cooling by air quenching
for heat strengthening or tempering.
With continuing reference to Figure 3, the actuator 62 previously
described includes a lower vertical operator 74 for moving the lower press ring
support 50 and the lower press ring 52 vertically relative to the conveyor wheels 44
and also includes an upper vertical operator 76 for moving the upper press mold 58
vertically relative to framework of the press station and relative to the lower press
ring.
With reference to Figures 5 and 6, the upper mold 58 is supported on
a mold support 78 with its surface 60 facing downwardly during use with a
downwardly convex shape as shown in Figure 5. This downwardly facing mold
surface 60 has curvature in transverse directions as illustrated by the phantom line C
that is curved along the direction of conveyance and by the phantom line T that is
curved along a direction transverse to the direction of conveyance.
As illustrated in Figures 7 and 8, the lower press ring 52 includes end
portions 80 spaced laterally from each other relative to the direction of conveyance
and have upwardly concave curved shapes along the direction of conveyance.
Actually due to their somewhat converging shape as illustrated best in Figure 8, the
lower press ring end portions 80 converge slightly along the direction of conveyance
and thus also extend to some extent transversely to the direction of conveyance C.
The lower press ring 52 also includes intermediate portions 82 spaced from each other
along the direction of conveyance with upwardly concave curved shapes extending
transversely to the direction of conveyance between the end portions 80 of the lower
press ring. As is hereinafter more fully described, the end portions 80 and the
intermediate portions 82 of the lower press ring 52 are mounted on the lower support
50 so as to be movable vertically together with each other and independently of each
other. More specifically, cylinders 84 respectively associated with the lower press
ring end portions 80 are connected to the press ring actuator 62 and operated to
provide vertical upward movement of the press ring end portions during the press
forming operation as described below. This upward movement of the lower press
ring end portions 80 relative to the intermediate portions 82 is illustrated in Figures
9 and 10.
With reference to Figure 11, the press forming cycle begins as the
initially formed glass sheet is conveyed on the wheel bed 34 into the press station 12
above the lower ring 52 and below the upper mold 58 with its downwardly facing
surface 60 which has convex curvature both along and transverse to the direction of
conveyance in complementary relationship to the end portions 80 and intermediate
portions 82 of the lower press ring 52. The initially formed glass sheet G then has
upper end portions 86 with straight line elements and an intermediate portion 88 that
also has straight line elements as previously discussed.
After the initially formed glass sheet is received within the press station
as shown in Figure 11, the processing proceeds as the lower press ring 52 is moved
upwardly by the press system actuator as previously described to lift the glass sheet
upwardly off of the conveyor wheel bed 34 as shown in Figure 12. The end portions
80 of the lower press ring 52 are then moved upwardly relative to the intermediate
portions 82 of the lower press ring to press the end portions 86 of the glass sheet G
against the downwardly facing surface 60 of the upper mold 58 as shown in Figure 13.
This upward movement of the lower press ring end portions 80 proceeds without an
accompanying movement of the intermediate portions 82 of the lower press ring so
that the ring end portions move upwardly relative to the intermediate portions. More
specifically, the intermediate portions 82 of the lower press ring 52 do not move
upwardly as fast as its end portions 80 during the upward movement of the end
portions 80 whose pressing of the glass sheet end portions 86 against the mold surface
60 provides curvature to their straight line elements along the direction of conveyance.
The intermediate portion 88 of the glass sheet G which has not yet contacted the mold
surface 60 still has its straight line elements at this stage of the press cycle. It is also
possible for the intermediate portions 82 of the lower press ring 52 to remain
stationary during the continued upward movement of the end portions 80, however
this results in a longer cycle time.
The press ring actuator moves the intermediate portions 82 of the lower
press ring 52 upwardly relative to the press ring end portions 80 to press the
intermediate portion 88 of the glass sheet G against the curved mold surface to provide
curvature to its straight line elements along the direction of conveyance. Thus, the
entire glass sheet has curvature along transverse directions.
When glass sheets are formed with curvature in transverse directions,
the periphery of the glass sheet is too long to provide the forming without extra glass
being present, and this extra glass is greatest at the locations farthest from the glass
center, i.e., at the end portions 86. By forming the glass sheet end portions 86 with
the transverse curvature initially, the excess peripheral glass is reduced at these
locations and shared with the edges of the intermediate portion.
The press forming of this application has particular utility with vehicle
windshields where the end portions of the glass sheet are mounted on the front
windshield pillars at locations where any distortion causes greater optical problems
than at the upper roof edge of the windshield and the lower cowl edge that extend
along the opposite extremities of the glass sheet intermediate portion 88.
It should be mentioned that the spacing between the intermediate
portion 88 of the glass sheet and the mold surface 60 as shown in Figure 13 is
exaggerated for purposes of illustration. More specifically, for a conventional size
vehicle windshield glass sheet, this spacing is only nominally about 3 centimeters
(slightly more than an inch). Furthermore, the processing can proceed even if the
intermediate portion 88 of the glass sheet contacts the upper mold surface 60 while the
glass sheet end portions are being pressed against the upper mold surface so long as
there is no significant curvature provided to the straight line elements of the glass
sheet intermediate portion until after the glass sheet end portions have been pressed
against the upper mold surface to provide the curvature to their straight line elements.
The term "no significant curvature" as used herein means the maximum "depth of
curvature" from the glass sheet to a straight line between its extremities to which its
straight line elements extend is no greater than 20% and preferably less than 10% of
the maximum "depth of curvature" after the intermediate portion of the glass sheet has
been fully formed.
With reference to Figures 7-10, the intermediate portions 82 of the
lower press ring 52 are mounted on the support frame 50 by adjusters 90 which, as
disclosed, are threaded adjusters whose rotational adjustment raises and lowers the
adjacent portion of the intermediate portion to provide the required shape. A pair of
connections generally indicated by 92 mount the end portions 80 of the lower press
ring on the support frame 50 for vertical movement with respect thereto and with
respect to the intermediate portions 82 of the lower press ring. The connections 92 as
disclosed include pivotal arms 94 having first ends 96 pivotally mounted on the
support frame 50 and second ends 98 that respectively mount the press ring end
portions 80 at their opposite extremities.
As best shown in Figure 7, the lower press ring end portions include
operators 100 which each have a rotatable shaft 102 mounted for rotation on the
support frame 50 by an associated pair of bearings 104. Adjacent one end of the shaft
102, a lever arm 106 has a pivotal connection 108 to the piston connecting rod of the
cylinder 84 whose operation provides the independent movement of the lower press
ring end portions 80. The forming station actuator 62 in addition to operating the
lower press ring operator 74 and the upper press mold operator 76, also operates the
cylinders 84.
Each end of each shaft 102 also includes a lever arm 110 which, as best
shown in Figures 9 and 10, is pivotally connected to one end of an adjuster 112 whose
other end is connected to an extension 114 of the adjacent second end of the pivotal
arm 94 of the associated ring end portion connection 92. Threaded adjustment of the
adjusters 112 provides vertical adjusting movement of the associated pressed ring end
portion 80 relative to the press ring intermediate portions 82. Since the lever arm 106
of each operator 100 is on the opposite side of the associated shaft 102, downward
movement of the piston connecting rod of cylinder 84 provides upward movement of
the associated pressed ring end portion 80 relative to the press ring intermediate
portions 82. After the press ring end portions 80 have provided the curvature to the
straight line elements of the glass sheet end portions 86 as previously described in
connection with Figure 13, the fluid pressure suppled to the cylinders 84 can be
reduced to facilitate movement of the glass sheet end portions along the mold surface
as the intermediate portion is moved upwardly as shown in Figure 14 to complete the
forming. The amount of this movement to accommodate the difference in the chordal
lengths of the glass sheet between Figures 13 and 14 is relatively small and operation
to date has shown that satisfactory forming can be performed without the pressure
reduction even though it may be helpful for some shapes.
While exemplary embodiments are described above, it is not intended
that these embodiments describe all possible forms of the invention. Rather, the
words used in the specification are words of description rather than limitation, and it
is understood that various changes may be made without departing from the spirit and
scope of the invention. Additionally, the features of various implementing
embodiments may be combined to form further embodiments of the invention.

WHAT IS CLAIMED IS:
1. A method for forming glass sheets comprising:
initially forming a heated flat glass sheet to an upwardly concave
curved shape with upper end portions and a lower intermediate portion extending
between the upper end portions, with the upper end portions and intermediate portion
having straight line elements, and with the glass sheet curved transversely to the
straight line elements;
locating the initially formed glass sheet below an upper mold having
a downwardly facing surface with downwardly convex curvature along transverse
directions;
moving the end portions of the glass sheet upwardly relative to the
intermediate portion to initially contact the end portions of the glass sheet with the
downwardly facing surface of the upper mold to form the straight line elements of the
end portions with curvature while the intermediate portion of the glass sheet still has
straight line elements without any significant curvature; and
thereafter moving the intermediate portion of the glass sheet upwardly
relative to its end portions to contact the intermediate portion of the glass sheet with
the downwardly facing surface of the upper mold to also form the straight line
elements of the intermediate portion with curvature so the entire glass sheet is curved
along transverse directions.
2. A method for forming glass sheets as in claim 1 wherein the
glass sheet is initially formed with a generally cylindrical shape that has the straight
line elements.
3. A method for forming glass sheets as in claim 1 wherein the
glass sheet is initially formed with a conical shape that has the straight line elements.
4. A method for forming glass sheets as in claim 1 wherein the
straight line elements of the end portions of the glass sheet are formed with curvature
against the upper mold before the intermediate portion contacts the upper mold.
5. A method for forming glass sheets as in claim 1 wherein the
end portions of the glass sheet are each initially pressed against the downwardly facing
surface of the upper mold with a predetermined force that is subsequently reduced to
facilitate movement of the end portions of the glass sheet along the downwardly facing
surface of the upper mold as the intermediate portion of the glass sheet continues to
move for forming against the downwardly facing surface of the upper mold.
6. A method for forming glass sheets as in claim 1 wherein the
heated flat glass sheet is initially formed within a heating chamber on a conveyor by
inclined rolls of progressively increasing inclination along a direction of conveyance
and is then conveyed out of the heating chamber to a press station at which the upper
mold is located.
7. A method for forming glass sheets as in claim 6 wherein the
initially formed glass sheet is lifted upwardly off of the conveyor in the press station
by a lower ring that is moved upwardly from below the glass sheet and has: (a) end
portions spaced laterally from each other relative to the direction of conveyance with
upwardly concave curved shapes along the direction of conveyance, and (b)
intermediate portions spaced from each other along the direction of conveyance with
upwardly concave curved shapes extending transversely to the direction of conveyance
between the end portions of the lower ring, after the lower ring lifts the glass sheet
upwardly off the conveyor the end portions of the lower ring being moved upwardly
relative to the intermediate portions of the lower ring to contact and form the end
portions of the glass sheet against the downwardly facing surface of the upper mold
while the intermediate portion of the glass sheet is still located below the downwardly
facing surface of the upper mold, and after the end portions of the lower ring form the
end portions of the glass sheet against the downwardly facing surface of the upper
mold the intermediate portions of the lower ring being moved upwardly to contact and
form the intermediate portion of the glass sheet with the downwardly facing surface
of the upper mold to complete the press forming.
8. A method for forming glass sheets as in claim 7 wherein the
end portions of the glass sheet are each initially pressed against the downwardly facing
surface of the upper mold by the end portions of the lower ring with a predetermined
force that is subsequently reduced to facilitate movement of the end portions of the
glass sheet along the downwardly facing surface of the upper mold as the intermediate
portion of the glass sheet continues to be moved upwardly by the intermediate portions
of the lower ring into contact for forming against the downwardly facing surface of
the upper mold.
9. A glass sheet press station comprising:
a conveyor for conveying along a direction of conveyance a heated and
initially formed glass sheet having an upwardly concave shape including upper end
portions spaced laterally from each other with respect to the direction of conveyance
and a lower intermediate portion that extends transversely with respect to the direction
of conveyance between the end portions, with the upper end portions and the lower
intermediate portion having straight line elements, and with the glass sheet curved
transversely to the straight line elements;
a lower ring over which the glass sheet is conveyed, the lower ring
including end portions spaced laterally from each other relative to the direction of
conveyance with upwardly concave curved shapes along the direction of conveyance,
the lower ring including intermediate portions spaced from each other along the
direction of conveyance with upwardly concave curved shapes extending transversely
to the direction of conveyance between the end portions of the lower ring, and the end
portions and the intermediate portions of the lower ring being movable vertically
together with each other and independently of each other;
an upper mold located above the lower ring and having a downwardly
facing surface with downwardly convex curvature both along and transverse to the
direction of conveyance in complementary relationship to the curvature of the end
portions and intermediate portions of the lower ring; and
an actuator for: initially moving the end portions and the intermediate
portions of the lower ring upper upwardly together with each other to lift the initially
formed glass sheet upwardly off of the conveyor; then moving the end portions of the
lower ring upwardly relative to the intermediate portions of the lower ring to move the
end portions of the glass sheet upwardly into contact with the downwardly facing
surface of the upper mold to provide curvature to the straight line elements of the end
portions of the glass sheet while the intermediate portion of the glass sheet has not yet
been formed by the upper mold; and thereafter moving the intermediate portions of
the lower ring upwardly relative to its end portions to contact the intermediate portion
of the glass sheet with the downwardly facing surface of the upper mold to provide
curvature to the straight line elements of the intermediate portion of the glass sheet so
the entire glass sheet has curvature in transverse directions.
10. A glass sheet press station as in claim 9 wherein the lower ring
includes a support frame on which the intermediate portions of the lower ring are
mounted for movement with the support frame, and a pair of connections that
respectively mount the end portions of the lower ring on the support frame for vertical
movement with respect thereto and with respect to the intermediate portions of the
lower ring.
11. A glass sheet press station as in claim 10 wherein the pair of
connections include pivotal arms having first ends that are pivotally mounted on the
support frame and second ends that respectively mount the end portions of the lower
ring.
12. A glass sheet press station as in claim 9 wherein the actuator
includes cylinders for applying upward force to the end portions of the lower ring so
as to move the lower ring end portions upwardly relative to the lower ring
intermediate portions to provide the movement of the end portions of the glass sheet
upwardly into contact with the downwardly facing surface of the upper mold to
provide forming thereof along the direction of conveyance while the intermediate
portion of the glass sheet has not yet been formed by the upper mold.
13. A glass sheet press station as in claim 12 wherein the actuator
operates the cylinders to reduce the upward force applied to the end portions of the
lower ring as the intermediate portions of the lower ring are moved upwardly relative
to the end portions of the lower ring to facilitate movement of the glass sheet end
portions relative to the downwardly facing surface of the upper mold as the
intermediate portions of the lower ring move the intermediate portion of the glass
sheet into contact with the downwardly facing surface of the upper mold to provide
the forming thereof along the direction of conveyance.
14. A glass sheet press station as in claim 9 wherein the lower ring
includes adjustors for adjusting the positions of its end portions and intermediate
portions relative to each other.