METHOD AND APPARATUS FOR POSITIONING GLASS SHEETS FOR FORMING
TECHNICAL FIELD
[OOOl] This invention relates to a method and system for positioning glass sheets for forming
and also involves forming of glass sheets after the positioning.
BACKGROUND
[0002] Glass sheets after heating have previously been formed by conveyance on a lower roll
bed to above a forming mold that is moved upwardly to provide the forming, see United States
patent 6,543,255. The roll bed can include wheels or, as disclosed in United States Patent
Application Publication No. US20 1 110247367 entitled PRESS BENDING STATION AND
METHOD FOR BENDING HEATED GLASS SHEETS by Dean M. Nitschke et al., can include
elongated rollers or wheels and elongated rollers that are selectively attachable and detachable for
rotational driving and positioning to provide the required shape for the mold to move vertically from
below to above the conveyor for lifting of the heated glass sheet for the forming. The above
referenced patent and application are hereby incorporated by reference.
SUMMARY
[0003] One object of the present invention is to provide an improved method for positioning
a heated glass sheet with respect to a forming mold for forming.
[0004] In carrying out the above object, the method for positioning a heated glass sheet with
respect to a forming mold for forming is performed by conveying a heated glass sheet horizontally
on a roll conveyor at a conveyor speed in a direction of conveyance along a path toward a vertically
aligned position above a forming mold. A pair of positioners are moved along the direction of
conveyance at laterally spaced locations in the path of the conveyed glass sheet and at a slower
speed than the conveyor speed so the conveyed glass sheet contacts the positioners for a sufficient
time in order to rotate the glass sheet on the roll conveyor to correct any rotation from a design
rotational position with respect to the forming mold. The positioners are then moved along the
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direction of conveyance at a faster speed than the conveyor speed and the conveyed glass sheet so as
to move out of contact therewith in order to permit the glass sheet to move into vertical alignment
with the forming mold for forming.
[0005] As disclosed, the conveyor speed and the speed of the slower moving positioners are
decelerated at the same rate as each other prior to the positioners moving faster than the speed of the
conveyor. Also, after the deceleration of the speed of the conveyor and the speed of the positioners
at the same rate as each other and before the positioners begin moving faster than the speed of the
conveyor, the speed of the conveyor continues to decelerate and the speed of the positioners
accelerates until the speed of the conveyor and the speed of the positioners are the same as each
other whereupon the positioners move out of contact with the glass sheet as the speed of the
conveyor continues to decelerate and the speed of positioners continues to accelerate. Also, the
positioners move out of contact with the glass sheet at a location upstream a predetermined distance
along the direction of conveyance from the location at which the glass sheet moves into vertical
alignment with the forming mold
[0006] The forming mold as disclosed is a peripheral forming mold having an open center
and includes a downstream portion adjacent which the movement of the positioners takes place
within the open center of the peripheral forming mold. After moving out of contact with the glass
sheet, the positioners are moved downwardly and the glass sheet moves above the positioners toward
a location at which the periphery of the glass sheet moves above and into alignment with the
peripheral forming mold. The peripheral forming mold as disclosed is then moved upwardly at a
time and speed to lift the moving glass sheet from the roll conveyor for forming of the glass sheet.
More specifically, the peripheral forming mold is moved upwardly at a time and speed to lift the
glass sheet from the roll conveyor after the glass sheet has been conveyed a predetermined distance
along the direction of conveyance subsequent to the positioners moving out of contact with the glass
sheet. An upper mold is disclosed as being moved downwardly and the glass sheet is press formed
between the forming mold and the upper mold.
[0007] In one disclosed practice of the method, the heated glass sheet is preformed prior to
being conveyed into alignment with the forming mold, and in another disclosed practice of the
method the heated glass sheet is conveyed with a flat shape into alignment with the forming mold.
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[OOOS] Another object of the present invention is to provide improved apparatus for
positioning a heated glass sheet for forming.
[0009] In carrying out the immediately preceding object, the apparatus for positioning a
heated glass sheet for forming includes a roll conveyor for conveying a heated glass sheet
horizontally at a conveyor speed in a path along a direction of conveyance outwardly from a heating
furnace and away from the furnace, and includes a conveyor drive that drives the roll conveyor. The
apparatus has an upwardly facing forming mold with an upwardly concave curved shape, and the
apparatus also has a pair of positioners laterally spaced at a location along the direction of
conveyance in the path of the conveyed glass sheet. A positioner drive of the apparatus moves the
pair of positioners along the direction of conveyance. A controller of the apparatus operates the
conveyor drive and the positioner drive so: (a) the pair of positioners are initially moved along the
direction of conveyance at a slower speed than the conveyor speed such that the conveyed glass sheet
contacts the positioners to provide rotational adjustment of the glass sheet; and (b) the controller
subsequently moves the positioners faster than the conveyor speed and the conveyed glass sheet so
the positioners move out of contact with the glass sheet in preparation for the glass sheet moving over
and into vertical alignment with the forming mold.
[OOlO] The controller disclosed operates the conveyor drive and the positioner drive so the
speed of the conveyor and the speed of the positioners are decelerated at the same rate as each other
prior to the positioners moving faster than the conveyor speed. More specifically, the controller
disclosed operates the conveyor drive and the positioner drive so, after the deceleration of the
conveyor and the positioners at the same rate as each other and before the positioners begin moving
faster than the speed of the conveyor, the speed of the conveyor continues to decelerate and speed of
the positioners accelerates until the speed of the conveyor and the speed of the positioners are the
same as each other whereupon the positioners move out of contact with the glass sheet as the speed of
the conveyor continues to decelerate and the speed of positioners continues to accelerate. Also, the
positioners move out of contact with the glass sheet at a location upstream a predetermined distance
along the direction of conveyance from the location at which the glass sheet moves into vertical
alignment with the forming mold.
[OOll] The disclosed forming mold has an open center and a peripheral shape that
corresponds to the periphery of the glass sheet, the forming mold has a downstream portion, the pair
of positioners are mounted within the open center of the forming mold adjacent its downstream
portion, and a mold actuator moves the forming mold upwardly to lift the moving glass sheet from
the conveyor for forming. The disclosed apparatus also includes an upper mold that cooperates with
the forming mold to press form the glass sheet.
[0012] The apparatus is disclosed in one embodiment as having its roll conveyor including
rolls that provide an upwardly concave conveying shape for conveying a heated glass sheet that is
previously formed, and in another embodiment the apparatus is disclosed as having its roll conveyor
including rolls that provide a flat plane of conveyance for conveying a flat heated glass sheet for
forming.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIGURE 1 is a schematic side elevation view of a glass sheet press forming system
that includes positioning apparatus for positioning a heated glass sheet on a forming mold to provide
positioning and forming according to the present invention.
[0014] 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.
[0015] FIGURE 3 is a schematic cross sectional view taken through the system along line 3-
3 in Figure 1 at its press or forming station to illustrate the construction of a lower forming mold
provided by a ring and also illustrating the construction of an upper press mold, which molds are
movable between the solid and phantom line indicated positions to press bend the initially roll
formed glass sheet.
[0016] FIGURE 4 is a view of another embodiment of the system whose positioning
apparatus positions and then forms a flat glass sheet according to the invention.
[0017] FIGURE 5 is a cross-sectional view taken along the direction of line 5-5 in Figure 4
to further illustrate the flat shape of the glass sheet during the positioning prior to its forming.
[0018] FIGURE 6 is a perspective view of a forming mold of the apparatus viewed from a
lateral upstream direction and showing positioners in preparation for a positioning operation of a
conveyed glass sheet.
[0019] FIGURE 7 is another view of the forming mold taken from a lateral downstream
position and showing the positioners after movement along the direction of conveyance to provide
positioning of a conveyed glass sheet into vertical alignment with the mold.
[0020] FIGURE 8 is a partial view taken similarly to Figure 6 showing an upper location of
the positioners during positioning of the glass sheet with respect to the mold.
[0021] FIGURE 9 is a view similar to Figure 8 but showing a lower position of the
positioners that allows the positioned glass sheet to move above and into vertical alignment with the
mold after the positioning.
[0022] FIGURE 10 is a schematic top plan view showing the manner in which a glass sheet
is rotated for positioning and vertical alignment with the forming mold for forming.
[0023] FIGURE 11 is a timing chart that illustrates the positioning and forming cycle by the
movement of the conveyor, movement of the positioners, and movement of the forming mold
upwardly to perform the forming in a press manner with an associated upper mold.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0024] With reference to Figure 1 of the drawings, a system for forming glass sheets is
generally indicated by 10 and includes a forming station 12 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 invention.
[0025] 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
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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.
[0026] 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
for heating. 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, which is also referred to as bending
in the glass sheet industry.
[0027] 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 32,, 32b, 32, 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 formed shape of the glass sheet with straight line elements 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.
[0028] 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
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press forming station 12 includes a conveyor having a lower wheel or roll 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 42 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 base
structure 38. A drive mechanism provides rotational driving of the wheel 44 of each wheel assembly
40 upon connection thereof to the lower base structure 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 horizontal and
inclined as disclosed by United States patent application Serial No. 121756,521 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 has herein been incorporated by reference.
[0029] As illustrated in Figure 3, a lower press ring support 50 of the press forming
apparatus 36 supports a lower forming mold or 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. Positioning apparatus 54 of the system includes positioners 55
(Figures 6-10) that rotate a conveyed glass sheet G to provide alignment with the forming mold 52
for forming.
[0030] As also 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 of the lower press
ring 52.
[003 11 A mold 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 58 to press form the
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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 for cooperating
with the lower press ring to press form the glass sheet. The actuator 62 includes a lower mold
actuator 621, and an upper mold actuator 62,, that respectively move the lower forming mold 52 and
the upper mold 58 upwardly and downwardly. However, it should be appreciated that it is possible
to only move the lower forming mold 52 upwardly and downwardly without any movement of the
upper mold.
[0032] 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 C 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 at which they support the
wheel assemblies 40. This rail height positioning is provided by unshown adjusters to provide the
curved shape of the wheel bed along a direction transverse to the direction of conveyance.
[0033] As also shown in Figure 3, the upper press mold 58 has its forming face 60 provided
with an array of holes 61 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 subsequent operation of the actuator 62, the lower press ring
52 is moved downwardly and the upper press mold 58 is moved upwardly and 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 in Figure 1 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 between the lower and upper quench heads 74
and 76.
[0034] With reference to Figures 4 and 5, another embodiment of the glass sheet forming
system 10' is similar to the embodiment of Figure 3 but operates to provide positioning and forming
of flat glass sheets without any preforming as with the previously described embodiment. Thus, like
components thereof have the same reference numerals that are primed for the forming station 12',
furnace 14', and press forming apparatus 36' as well as the base structure 38'.
[0035] As illustrated in Figures 1 and 4, each embodiment of the system 10, 10' includes a
controller 78 connected to the mold actuator 62, the shuttle actuator 70, a conveyor drive 80, and the
positioning apparatus 54 to coordinate the system operation for the positioning and forming cycle.
The systems 10 and 10' each have an unshown sensor like conventional glass sheet forming systems
adjacent the junction between the exit end of the roll forming station 16 and the upstream end of the
forming station 12 or 12' for sensing the location of a downstream extremity at the lateral center of
the conveyed glass sheet.
[0036] As shown in Figures 6 and 7, the upwardly facing lower forming mold 52 can have
curvature both laterally with respect to the direction of conveyance C and along the direction of
conveyance C and is mounted on the mold support 50 by adjusters of any suitable type as
schematically illustrated by 84 so as to provide adjustment to the designed upwardly concave shape
to be formed. The pair of laterally spaced positioners 55 are mounted by a positioner drive 86 of the
positioning apparatus 54 for movement along the direction of conveyance between the upstream
position shown in Figure 6 and the downstream position shown in Figure 7. The controller 78
(Figures 1 and 4) operates the conveyor drive 80 and the positioner drive 86 in a coordinated manner
and provides rotational positioning of a conveyed glass sheet G so as to be properly aligned upon
conveyance above the mold 52 for the forming. As the glass sheet is conveyed along the direction of
conveyance above the forming mold 52, the laterally spaced positioners 55 are moved along the
direction of conveyance from the upstream position of Figure 6 toward the downstream position of
Figure 7 but at a slower rate than the conveyor such that the positioners contact the glass sheet.
[0037] As illustrated in Figure 10, the glass sheet G as shown by solid line illustration is
initially located counterclockwise from the design rotational position and the contact with the slower
moving positioners 55 rotates the glass sheet to the design rotational position illustrated by dash
lines so as to be vertically aligned with the forming mold 52 upon farther conveyance in preparation
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for the press forming. If the glass sheet is initially located clockwise from the design rotational
position, the slower moving positioners 55 rotate the glass sheet counterclockwise to the design
rotation position. Furthermore, the positioners will not rotate the glass sheet if it initially is in the
design rotational position and thus does not require any rotation. After any rotation in either
direction, the controller moves the positioners 55 faster than the conveyor speed and the conveyed
glass sheet so that the positioners move out of contact with the leading edge of the glass sheet in
preparation for the glass sheet moving over and into vertical alignment with the forming mold 52.
[0038] It should be mentioned that the amount of rotation to provide the rotational alignment
of the glass sheet G with the forming mold 52 does not have to be particularly great. More
specifically, it has been found that the ability to adjust for a leading amount of about 5 mm or a
trailing amount of about 5 mm, for a total range of 10 mm, is sufficient to provide rotational
adjustment to the design position to correct for any rotational variance.
[0039] As illustrated in Figure 8, the positioning apparatus 54 includes cylinders 88 whose
piston connecting rods 90 are movable vertically and support the positioners 55 for movement
between the Figure 8 upper position where the positioners contact the glass sheet and a lower
position shown in Figure 9 for allowing the glass sheet to move over the positioners and into vertical
alignment above the forming mold 52. More specifically, the forming mold 52 as shown in Figures
6 and 7 has an open center 92 and a peripheral shape that corresponds to the periphery of the glass
sheet. A downstream portion 94 of the forming mold 52 extends laterally with respect to the
direction of conveyance, and the positioners 55 move toward this downstream portion from the
position of Figure 6 to the position of Figure 7 during the slower movement of the positioners than
the conveyor to provide the glass sheet rotation into rotational alignment with the mold periphery.
Prior to the positioners 55 reaching the downstream mold portion 94, the cylinders 88 move the
positioners downwardly so the glass sheet can move over the positioners and over the forming mold
52 and into vertical alignment with its peripheral shape.
[0040] The systems 10, 10' each have an unshown electric eye sensor of the electromagnetic
wave type like conventional glass sheet forming systems at the lateral center of the conveyed glass
sheet adjacent the junction between the exit end of the roll forming system 16 or furnace 14' and the
upstream end of the forming station 12 or 12'. This type of sensor senses the downstream extremity
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at the lateral center of the conveyed glass as it approaches or moves into the forming station for
forming. Such sensors conventionally initiate operation of the associated forming apparatus.
Normally there is about one meter, i.e. 1000 mm, of travel from the sensing to the design position at
the mold apparatus where the forming takes place. During that amount of travel, the glass sheet
lateral midpoint where the sensing normally takes place can vary plus or minus about 3 mm and the
lateral extremities due to rotation during the entire conveyance can vary plus or minus about 5 mm
from the lateral midpoint, for a total variance in the range of about plus or minus 8 mm.
[0041] With the present systems, the electric eye sensor adjacent the junction between the
exit end of the roll forming system 16 or furnace 14' and the upstream end of the forming station 12
or 12' is connected to the controller 78 to initiate operation of the positioning apparatus 54 in
coordination with the conveyor and after the positioners complete the positioning and move out of
contact with the glass sheet, there is normally less than 100 mm of travel to the design position
where the glass sheet is aligned with the forming mold 52 such that there is then normally only a
total variance of the glass position from the design position in the range of about 1.2 mm. More
specifically, after the positioners 55 move out of contact with the glass sheet, the controller 78
operates the conveyor and the mold actuator 62 in a coordinated manner that provides more accurate
positioning of the glass sheet with respect to the forming mold 52 as is hereinafter more fully
described.
[0042] With reference to the timing chart shown in Figure 11, the X coordinate or abscissa
represents the time during a cycle of positioning and forming and the Y coordinate or ordinate
represents speed of movement. More specifically, the line C represents the conveyor speed along
the horizontal direction of conveyance, the line P represents the speed of the positioners along the
horizontal direction of conveyance, and the line M represents the speed of vertical movement of the
forming mold 52 under the operation of the controller 78. The conveyor speed C initially moves at a
constant index speed during which the electric eye sensor at the time of line S through the operation
of the controller 78 initiates the operation of the positioning apparatus 54. Subsequently the
conveyor speed C begins to decelerate at a constant rate and the positioners are accelerated until
reaching a maximum speed that is slightly less than the conveyor speed and the positioners then
begin to decelerate at the same rate as the conveyor. The slower moving positioners contact the
glass sheet and provide any required rotational adjustment and also provide any required
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longitudinal adjustment with respect to the conveyor before reaching the time at phantom line 96. If
no rotational adjustment is required, both positioners will contact the glass sheet sooner than is the
case when the positioners provide the rotational positioning of the glass as previously described.
After the phantom line 96 time, the conveyor speed continues to decelerate and the positioner speed
increases until both the conveyor and the positioners have the same speed at the time of intersection
98. The positioners 55 then move out of contact with the conveyed glass sheet as the positioner
speed continues to increase and the conveyor speed continues to decrease. After the disengagement
of the positioners 55 from the glass sheet, the positioners move downwardly as previously described
and their speed is decelerated until stopping at the locations shown in Figures 7 and 9. The conveyor
speed and hence the speed of conveyance of the glass sheet then continues to decelerate and the
lower mold embodied by the press ring is moved upwardly as shown by the mold line M, with the
upward movement initially being relatively rapid to lift the glass sheet from the conveyor whereupon
the upward movement is decreased to a relatively slow movement during the pressing with the upper
mold and ultimately terminated after completion of the pressing of the glass sheet.
[0043] The glass sheet moves out of contact with the positioners at the intersection 98 which
is a predetermined distance along the direction of conveyance from the location at lift line L where
the lower mold is moved upwardly a sufficient distance to lift the glass sheet from the conveyor and
terminate its conveyance. This spacing together with a predetermined speed of the conveyor and the
speed of the lifter facilitates correct timing of the actuator 62 for lifting the glass sheet as it is being
conveyed into vertical alignment with the mold in order to provide proper positioning for the lifting
that terminates the glass sheet conveyance.
[0044] Before time line 96 shown in Figure 11, both the conveyor and the positioners 55 are
decelerating at the same rate as each other but the speed of the positioners is slower than the speed of
the conveyor, about 100 mm. per second as illustrated. The relevant part of the positioner action
starts as the glass sheet approaches the positioners and the positioners have reached their maximum
speed, about 100 mmlsecond slower than the conveyor, and have just started to decelerate with the
conveyor at the same rate. Preferably for a glass sheet that has not been rotated and for which the
electric eye sensor identified the glass sheet's leading edge correctly and assigned the conveyor's
current position to the glass sheet, or registered the glass sheet to the conveyor and for a glass sheet
which has not slipped on the conveyor after registration, the glass sheet will have a clearance
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separation of 10 mm from the positioners at the start of positioning as the positioners just start to
decelerate. The positioners will have a 10 mm head start and the ideal glass sheet just discussed will
catch up to and contact the slower moving positioners after the positioners have traveled 10 mm less
than the conveyor. Typically the relevant part of positioning takes place over a conveyor travel
distance of about 200 mm. During that conveyor travel, the positioners travel in the same direction
but travel 20 mm less than the conveyor travel distance. Thus, if the positioners were in contact with
the glass sheet from the start of their slower movement, they would retard the glass sheet movement
20 mm, but would only retard the ideal glass sheet 10 mm as discussed above.
[0045] After the rotational and longitudinal adjustment, the glass sheet will be at the time
line 96 of Figure 11 when the speed of the positioners accelerates as the speed of the conveyor
continues to decelerate. For an additional 1.5 mm of retarding movement of the glass sheet after
time line 96, the positioners are still going slower than the conveyor, so the glass sheet is still
pressed against the positioners. More specifically, at the time point 96, the glass sheet is slipping on
the conveyor rolls by 100 mm per second and is moving at the speed of the positioners. Between
time line 96 and time point 98, the speed of the glass sheet increases to the speed of the
conveyor. The coefficient of friction between glass sheet and the conveyor is then initially the
dynamic coefficient of friction rather than the static coefficient of friction because of the slippage
taking place. So the positioners must be accelerated slowly between time line 96 and time point 98
so they do not pull away from the glass sheet until the glass sheet has stopped slipping on the
conveyor and its speed of conveyance is the same as the conveyor speed. At time point 98, the
speed of the positioners and the speed of the conveyor, and hence also the speed of the glass sheet,
are the same, so there is no slippage and the conveyor then controls the speed of the glass sheet
conveyance. This is important because the positioners have delivered the glass sheet at time point
98 very accurately under the operation of the controller 78 in coordination with the conveyor so the
glass sheet conveyance to the design position with respect to the forming mold 52 can be accurately
controlled.
[0046] The conveyor, not the positioner, thus has control of the glass sheet movement for
about the last 80 mm before pick-up by the forming mold. This removes the inaccuracy of the
positioning provided only by the sensor as previously described and inaccuracy due to slip between
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the glass sheet and the rolls over the meter or so of travel from the sensor to time point 98. Time
point 98 is related very accurately to the mold design position by the controller 78 and coordinated
conveyor operation for electrically controlled delivery of the glass sheet to the design position for
the pick-up and forming.
[0047] After the positioning and press forming as described above, the forming mold 52 is
moved downwardly and the upper mold 58 is moved upwardly with the glass sheet thereon by the
provision of the vacuum previously discussed so that the delivery ring 72 can be moved into the
forming station to receive the formed glass sheet for final processing, either quenching or annealing
as previously discussed.
[0048] The total positioning and forming cycle time is less than 2 seconds and specifically is
about 1 213 seconds.
[0049] 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 positioning a heated glass sheet with respect to a forming mold,
comprising:
conveying a heated glass sheet horizontally on a roll conveyor at a conveyor speed in
a direction of conveyance along a path toward a vertically aligned position above a forming mold;
moving a pair of positioners along the direction of conveyance at laterally spaced
locations in the path of the conveyed glass sheet and at a slower speed than the conveyor speed so
the conveyed glass sheet contacts the positioners for a sufficient time in order to rotate the glass
sheet on the roll conveyor to correct any rotation from a design rotational position with respect to the
forming mold; and
then decelerating the speed of the conveyor and accelerating the speed of the
positioners until the speed of the conveyor and the speed of the positioners are the same as each
other and then continuing to increase the relative speed of the positioners with respect to the speed of
the conveyor so the positioners move out of contact with the conveyed glass sheet in order to permit
the glass sheet to move into vertical alignment with the forming mold for forming.
2. A method for positioning a heated glass sheet with respect to a forming mold
as in claim 1 wherein the speed of the conveyor and the speed of the positioners are decelerated at
the same rate as each other prior to decelerating the speed of the conveyor and accelerating the speed
of the positioners.
3. A method for positioning a heated glass sheet with respect to a forming mold
as in claim 2 wherein, after the speed of the conveyor and the speed of the positioners are the same
as each other, the speed of the conveyor continues to decelerate and the speed of the positioners
accelerates at a greater rate as the positioners move out of contact with the glass sheet.
4. A method for positioning a heated glass sheet with respect to a forming mold
as in claim 3 wherein the positioners move out of contact with the glass sheet at a location upstream
a predetermined distance along the direction of conveyance fiom the location at which the glass
sheet moves into vertical alignment with the forming mold.
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AMENDED SHEET - IPEAKJS
5. A method for positioning a heated glass sheet with respect to a forming mold
as in claim 1 wherein the forming mold is a peripheral forming mold having an open center and
including a downstream portion adjacent which the movement of the positioners takes place within
the open center of the peripheral forming mold.
6. A method for positioning a heated glass sheet with respect to a forming mold
as in claim 5 wherein after moving out of contact with the glass sheet the positioners are moved
downwardly and the glass sheet moves above the positioners toward a location at which the
periphery of the glass sheet moves above and into alignment with the peripheral forming mold.
7. A method for positioning a heated glass sheet with respect to a forming mold
as in claim 6 wherein the peripheral forming mold is moved upwardly at a time and speed to lift the
moving glass sheet from the roll conveyor for forming of the glass sheet.
8. A method for positioning a heated glass sheet for forming as in claim 7
wherein the peripheral forming mold is moved upwardly at a time and speed to lift the glass sheet
from the roll conveyor after the glass sheet has been conveyed a predetermined distance along the
direction of conveyance subsequent to the positioners moving out of contact with the glass sheet.
9. A method for positioning a heated glass sheet with respect to a forming mold
as in claim 6 wherein an upper mold is moved downwardly and the glass sheet is press formed
between the forming mold and the upper mold.
10. A method for positioning a heated glass sheet with respect to a forming mold
as in claim 1 wherein the heated glass sheet is preformed prior to being conveyed into alignment
with the forming mold.
11. A method for positioning a heated glass sheet with respect to a forming mold
as in claim 1 wherein the heated glass sheet is conveyed with a flat shape into alignment with the
forming mold.
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AMENDED SHEET - IPEAKJS
12. Apparatus for positioning a heated glass sheet for forming, comprising:
a roll conveyor for conveying a heated glass sheet horizontally at a conveyor speed in
a path along a direction of conveyance outwardly from a heating furnace and away from the furnace;
a conveyor drive that drives the roll conveyor;
an upwardly facing forming mold having an upwardly concave curved shape;
a pair of positioners laterally spaced at a location along the direction of conveyance in
the path of the conveyed glass sheet;
a positioner drive for moving the pair of positioners along the direction of
conveyance; and
a controller for operating the conveyor drive and the positioner drive so: (a) the pair
of positioners are initially moved along the direction of conveyance at a slower speed than the
conveyor speed such that the conveyed glass sheet contacts the positioners to provide rotational
adjustment of the glass sheet; and (b) the controller subsequently decelerating the speed of the
conveyor and the accelerating the speed of the positioners until the speed of the conveyor and the
speed of the positioners are the same as each other and then continuing to increase the relative speed
of the positioners with respect to the speed of the conveyor so the positioners move out of contact
with the glass sheet in preparation for the glass sheet moving over and into vertical alignment with
the forming mold.
13. Apparatus for positioning a heated glass sheet for forming as in claim 12
wherein the controller operates the conveyor drive and the positioner drive so the speed of the
conveyor and the speed of the positioners are decelerated at the same rate as each other prior to the
positioners moving faster than the conveyor speed.
14. Apparatus for positioning a heated glass sheet for forming as in claim 13
wherein the controller operates the conveyor drive and the positioner drive so, after the speed of the
conveyor and the speed of the positioners are the same as each other, the speed of the conveyor
continues to decelerate and speed of the positioners accelerates at a greater rate as the positioners
move out of contact with the glass sheet.
15. Apparatus for positioning a heated glass sheet for forming as in claim 12
wherein the forming mold has an open center and a peripheral shape that corresponds to the periphery of the glass sheet, the forming mold having a downstream portions, the pair of positioners being mounted within the open center of the forming mols adjacent its downstream portion, and a mold actuator for moving the forming mold upwardly to lift the moving glass sheet from the conveyor for forming.
16. Apparatus for positioning a heated glass sheet for forming as in claim 15 further including an upper mond that cooperates with the forming mold to press form the glass sheet.
17. Apparatus for positioning a heated glass sheet for forming as in claim 12
wherein the roll conveyor includes rolls that provide an upwardly concave conveying shape for conveying a heated glass sheet that is previously formed.
18. Apparatus for positioning a heated glass sheet for forming as in claim 13
wherein the roll conveyor includes rolls that provide a flat plane of conveyance for conveying a flat heasted glass sheet for forming.