U.S. patent application number 11/305386 was filed with the patent office on 2007-06-21 for method and apparatus for finishing a glass sheet.
Invention is credited to James William Brown, Charles Michael Darcangelo, Yawei Sun, Ljerka Ukrainczyk.
Application Number | 20070138228 11/305386 |
Document ID | / |
Family ID | 38172294 |
Filed Date | 2007-06-21 |
United States Patent
Application |
20070138228 |
Kind Code |
A1 |
Brown; James William ; et
al. |
June 21, 2007 |
Method and apparatus for finishing a glass sheet
Abstract
An apparatus for finishing a glass sheet comprising a pair of
fluid bearings having bearing surfaces in opposing relation, the
bearing surfaces spaced apart to define a channel for receiving the
glass sheet, each bearing surface having a plurality of pores
through which jets are introduced into the channel, the pores
positioned on the bearing surface such that the jets produce a
uniform fluid pressure across the bearing surface.
Inventors: |
Brown; James William;
(Painted Post, NY) ; Darcangelo; Charles Michael;
(Corning, NY) ; Sun; Yawei; (Horseheads, NY)
; Ukrainczyk; Ljerka; (Painted Post, NY) |
Correspondence
Address: |
CORNING INCORPORATED
SP-TI-3-1
CORNING
NY
14831
US
|
Family ID: |
38172294 |
Appl. No.: |
11/305386 |
Filed: |
December 16, 2005 |
Current U.S.
Class: |
226/97.1 |
Current CPC
Class: |
B24B 9/10 20130101; B24B
41/06 20130101 |
Class at
Publication: |
226/097.1 |
International
Class: |
B65H 20/00 20060101
B65H020/00 |
Claims
1. An apparatus for finishing a glass sheet, comprising: a pair of
fluid bearings having bearing surfaces in opposing relation, the
bearing surfaces spaced apart to define a channel for receiving the
glass sheet, each bearing surface having a plurality of pores
through which jets are introduced into the channel, the pores
positioned on the bearing surface such that the jets produce a
uniform fluid pressure across the bearing surface.
2. The apparatus of claim 1, wherein the pores are positioned such
that the jets produced from the pores interact.
3. The apparatus of claim 1, wherein a diameter of the pores is
greater than one-half the distance between adjacent pores.
4. The apparatus of claim 1, wherein each fluid bearing comprises a
flow plate, and a surface of the flow plate provides the bearing
surface.
5. The apparatus of claim 4, wherein the pores in the bearing
surface are provided by perforations in the flow plate.
6. The apparatus of claim 4, wherein the flow plate is made of a
porous material.
7. The apparatus of claim 6, wherein the porous material has an
average pore size in a range from 5 .mu.m to 150 .mu.m.
8. The apparatus of claim 6, wherein the porous material has an
average pore size in a range from 10 .mu.m to 100 .mu.m.
9. The apparatus of claim 6, wherein the porous material has an
average pore size in a range from 50 .mu.m to 80 .mu.m.
10. The apparatus of claim 6, wherein a thickness of the flow plate
is in a range from 10 mm to 50 mm.
11. The apparatus of claim 4, wherein each fluid bearing further
comprises an inlet through which fluid can be communicated to the
flow plate.
12. The apparatus of claim 1, further comprising a processing
device adjacent the fluid bearings for processing an edge of the
glass sheet.
13. The apparatus of claim 12, wherein the processing device
includes a finishing device for processing the edge of the glass
sheet and a shroud for containing contaminants generated during the
processing.
14. The apparatus of claim 12, further comprising a mechanism
coupled to the processing device for moving the processing device
relative to the fluid bearings.
15. The apparatus of claim 12, further comprising a mechanism
configured to engage the glass sheet and move the glass sheet
relative to the fluid bearings.
16. The apparatus of claim 15, wherein the mechanism comprises a
set of edge grippers and a linear slide coupled to the set of edge
grippers.
17. The apparatus of claim 1, further comprising a conveyor for
transporting the glass sheet into or out of the channel.
18. The apparatus of claim 17, wherein the conveyor is retractable
to allow a processing device access to an edge of the glass
sheet.
19. The apparatus of claim 1, further comprising edge grippers
extending into the channel for gripping edges of the glass
sheet.
20. The apparatus of claim 1, wherein each fluid bearing comprises
a plurality of the bearing surfaces in a stack.
21. A method of finishing a glass sheet, comprising: loading a
glass sheet in a channel defined between a pair of fluid bearings
having bearing surfaces, wherein each bearing surface has a
plurality of pores through which jets are introduced into the
channel and the pores are such that the jets produce a uniform
fluid pressure across the bearing surface; and finishing edges of
the glass sheet.
22. The method of claim 21, wherein finishing edges of the glass
sheet comprises grinding and/or polishing opposite edges of the
glass sheet.
23. The method of claim 21, wherein finishing edges of the glass
sheet comprises advancing a finishing device to the edges of the
glass sheet and moving the finishing device relative to the edges
of the glass sheet.
24. The method of claim 21, wherein finishing edges of the glass
sheet comprises advancing a finishing device to the edges of the
glass sheet and moving the edges of the glass sheet relative to the
finishing device.
25. The method of claim 21, wherein finishing edges of the glass
sheet comprises finishing opposite edges of the glass sheet
simultaneously.
26. The method of claim 21, further comprising cutting the glass
sheet from a continuous glass sheet prior to loading the glass
sheet into the channel.
27. The method of claim 26, wherein the continuous glass sheet is
produced by a fusion process and cutting the glass sheet is by a
travel anvil method.
28. The method of claim 27, wherein cutting the glass sheet is by a
thermal shock process.
29. The method of claim 26, further comprising removing beads from
edges of the glass sheet prior to loading the glass sheet into the
channel.
30. The method of claim 27, wherein removing beads is by a thermal
shock process.
31. The method of claim 21, wherein finishing edges of the glass
sheet comprises finishing a first set of edges of the glass sheet
followed by finishing a second set of edges of the glass sheet.
32. The method of claim 31, further comprising rotating the glass
sheet prior to finishing the second set of edges of the glass
sheet.
33. The method of claim 32, wherein the glass sheet is removed from
the channel prior to rotating the glass sheet and loaded into
another channel defined by a pair of fluid bearings prior to
finishing the second set of edges of the glass sheet.
34. The method of claim 21, further comprising washing the glass
sheet.
35. The method of claim 21, further comprising drying the glass
sheet.
36. The method of claim 21, further comprising coating the glass
sheet with a protective coating.
Description
BACKGROUND OF THE INVENTION
[0001] The invention relates generally to apparatus and methods for
finishing glass. More particularly, the invention relates to an
apparatus and a method for finishing a glass sheet having one or
more pristine surfaces.
[0002] Glass sheets having surfaces that are pristine and of
fire-polished quality are usually made by fusion processes. Such
glass sheets are useful in making devices such as flat panel
displays. A typical fusion process is illustrated in FIG. 1. Molten
glass 100 flows into a channel 102 of a fusion pipe 104 and
overflows from the channel 102 and down the sides of the fusion
pipe 104 in a controlled manner to form a sheet-like flow 106.
Because the outer surfaces 107, 109 of the sheet-like flow 106 do
not come into contact with any solid materials, they are pristine.
The sheet-like flow 106 passes through a controlled heated zone 108
to gradually cool down and therein form a continuous glass sheet
114 having a desired flatness and thickness with pristine
surfaces.
[0003] As the continuous glass sheet 114 emerges from the draw 112,
a piece of glass sheet is cut therefrom. The piece of glass sheet
is then subjected to a finishing process, which typically includes
precision cutting of the glass sheet into a desired size using
mechanical scoring, followed by edge grinding and/or polishing to
remove any sharp corners and edges. Glass cutting by mechanical
scoring and traditional edge finishing by grinding and polishing
produce glass particles that can contaminate the quality surface of
the glass sheet. Extensive washing and drying are needed to wash
off the glass particles. This extensive washing and drying impact
the finishing line and manufacturing costs. The glass particles can
also damage the quality surface of the glass sheet.
[0004] From the foregoing, there continues to be a desire for
improvements in finishing a glass sheet that would minimize the
finishing line and manufacturing costs and maintain the quality
surface of the glass sheet in a pristine condition.
SUMMARY OF THE INVENTION
[0005] In one aspect, the invention relates to an apparatus for
finishing a glass sheet which comprises a pair of fluid bearings
having bearing surfaces in opposing relation. The bearing surfaces
are spaced apart to define a channel for receiving the glass sheet.
Each bearing surface has a plurality of pores through which jets
are introduced into the channel. The pores are positioned on the
bearing surface such that the jets produce a uniform fluid pressure
across the bearing surface.
[0006] In another aspect, the invention relates to a method of
finishing a glass sheet which comprises loading a glass sheet in a
channel defined between a pair of fluid bearings having bearing
surfaces, wherein each bearing surface has a plurality of pores
through which jets are introduced into the channel and the pores
are such that the jets produce a uniform fluid pressure across the
bearing surface, and finishing edges of the glass sheet.
[0007] Other features and advantages of the invention will be
apparent from the following description and the appended
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 shows a continuous glass sheet produced by a fusion
process.
[0009] FIG. 2A is a side view of a fluid bearing system.
[0010] FIG. 2B is a detailed view of a single fluid bearing.
[0011] FIG. 3A shows pressure profile observed from non-interacting
water jets.
[0012] FIG. 3B shows pressure profile observed from interacting
water jets.
[0013] FIG. 4 is an elevated view of an apparatus for finishing a
glass sheet.
[0014] FIGS. 5A and 5B show an elevated view of an edge processing
device.
[0015] FIGS. 6A and 6B illustrate processing device and fluid
bearing arrangements.
DETAILED DESCRIPTION OF THE INVENTION
[0016] The invention will now be described in detail with reference
to a few preferred embodiments, as illustrated in accompanying
drawings. In the following description, numerous specific details
are set forth in order to provide a thorough understanding of the
invention. However, it will be apparent to one skilled in the art
that the invention may be practiced without some or all of these
specific details. In other instances, well-known features and/or
process steps have not been described in detail in order to not
unnecessarily obscure the invention. The features and advantages of
the invention may be better understood with reference to the
drawings and discussions that follow.
[0017] FIG. 2A shows a fluid bearing system 200 that supports a
glass sheet 202 while the edges of the glass sheet 202 are
processed, e.g., cut, ground, and/or polished. The fluid bearing
system 200 supports the glass sheet 202 without contacting the
quality zone (i.e., central portion) of the glass sheet 202. The
fluid used in the fluid bearing system 200 may be liquid or gas.
Where the fluid used in the fluid bearing system 200 is liquid, the
fluid bearing system 200 also keeps the glass sheet 202 wet,
thereby avoiding particle buildup on the surfaces of the glass
sheet 202 due to electrostatic charges. The fluid bearing system
200 includes a pair of fluid bearings 204 arranged in opposing
relation. The fluid bearings 204 are spaced apart to define a
channel 206 for receiving the glass sheet 202. A set of edge
grippers 208 grip the edges of the glass sheet 202 and prevent the
glass sheet 202 from slipping out of the channel 206. Preferably,
the edge grippers 208 do not touch the quality zone of the glass
sheet 202.
[0018] FIG. 2B is a more detailed view of a single fluid bearing
204. The fluid bearing 204 includes a stack of plenums 210. The
combined height (H) and width (W) of the stack of plenums 210 may
be similar to the height and width of the glass sheet (202 in FIG.
2A). The spacing (S) between the plenums 210 may be the same or may
be different. In some cases, there may be no spacing (S) between
some or all of the plenums 210. Alternatively, the stack of plenums
210 may be replaced with a single plenum. Each plenum 210 includes
a flow plate 212 and a support plate 216 coupled to the flow plate
212 by inlet devices 215. The support plate 216 is mounted on a
support frame 218. The support frame 218 may be coupled to
alignment or positional devices (not shown), which would then allow
the fluid bearing 208 to be adjustable either relative to an
opposing fluid bearing or glass sheet. The support plates 216 may
also be adjustably coupled to the support frame 218, for example,
so as to allow the spacing between the plenums 210 to be
adjustable. The edges of the flow plates 212 may be tapered or
flared to facilitate insertion of the glass sheet 202 into the
channel (206 in FIG. 2A).
[0019] Inlet devices 215 have inlets 214 through which fluid from a
fluid source (not shown) may be communicated in between the flow
plate 212 and support plate 216. The flow plate 212 has openings or
pores (213 in FIG. 2C) through which fluid from the inlets 214 can
flow into the channel (206 in FIG. 2A) to provide bearing support
to the glass sheet (202 in FIG. 2A) in the channel. In one example,
the pores 213 are perforations in the flow plate 212. In another
example, the flow plate 212 is made of a porous material. The fluid
communicated to the pores 213 may be a liquid or gas. Preferably,
the fluid does not interact with the glass sheet (202 in FIG. 2A).
Examples of suitable fluids include, but are not limited to, water
and air. Preferably, fluid jets emerge from the pores 213 to
produce a uniform fluid pressure across the bearing surface 211 of
the plenum 210. To produce the uniform fluid pressure, the fluid
jets should interact across the bearing surface 211 of the plenum
210. For interacting fluid jets, diameter (d in FIG. 2C) of the
pores 213 is preferably greater than 1/2 the distance between
adjacent pores (D in FIG. 2C).
[0020] FIG. 3A shows a pressure profile observed from
non-interacting water jets across a plenum surface. The pressure
profile shows that non-interacting fluid jets would produce
localized pressure on the surface of the glass sheet. When the
glass sheet is placed on such a non-interacting plenum surface, a
water film is created between the glass and the plenum. However,
the fluid pressure in the plane of the film water is non-uniform.
The fluid bearing is very sensitive to small perturbations in the
jets (such as those produced by hole size variation due to
machining tolerances). The fluid flow non-uniformities and small
misalignments of opposing jets can set up glass vibration that is
highly undesirable during an edge finishing process. FIG. 3B shows
a pressure profile observed from interacting water jets. As
illustrated, the pressure profile for interacting water jets does
not exhibit the localized pressure observed for the non-interacting
water jets.
[0021] In general, plenum design to achieve uniform fluid pressure
across a vertical bearing surface is much simpler when the flow
plate 212 is made of a porous material. Porous materials create
resistance to vertical flow due to gravity, thereby allowing
uniform fluid spread across the plenum surface and thickness. A
flow plate 212 made of a porous material exhibiting the properties
described above is preferred, i.e., diameter of the pores on the
bearing surface 211 is greater than 1/2 the distance between
adjacent pores. The use of thick, e.g., greater than approximately
1/8 in. (3.175 mm), porous material simplifies plenum design
because fluid can redistribute itself evenly across the bearing
surface 211. Examples of porous materials include, but are not
limited to, ultra-high molecular weight (UHMW) high density
polyethylene (HDPE), available from, for example, GenPore, Reading,
Pa. Porous materials having an average pore size in a range from 5
.mu.m to 150 .mu.m, preferably 10 .mu.m to 100 .mu.m, more
preferably 50 .mu.m to 80 .mu.m has been found to be useful. The
pores in the porous material may or may not be evenly distributed
and may have a variable size. The porous material thickness
typically ranges from 10 mm to 50 mm, preferably around 25 mm. The
fluid pressure drop through the thickness of the flow plate is
preferably no greater 50%.
[0022] FIG. 3B shows average pressure produced by interacting water
jets as a function of size of the channel (206 in FIG. 2A). As
shown, average pressure of interacting water jets decreases as
channel size increases. Average pressure of interacting water jets
is also influenced by the speed of the jets, which is influenced by
the size of the pores producing the jets and the rate at which
water is supplied to the pores producing the jets. In general, the
channel size and speed of the jets can be selected to achieve a
desired average pressure on the surface of the glass sheet.
Preferably, the pressure applied to the surface of the glass sheet
by the jets provides enough stiffness to support the glass sheet in
the channel such that the glass sheet does not make contact with
the bearing surfaces of the flow plates. In some cases, it may be
desirable to apply different amounts of pressure to different parts
of the glass. This can be achieved by making the flow plate with
different porosity sections, and tailoring the porosity in each
section to achieve a desired pressure across the corresponding
section of the glass or by changing water flow in a given
section.
[0023] FIG. 4 shows an apparatus 400 for finishing a glass sheet.
One or more of the apparatus 400, or alternate embodiments thereof,
may be used to achieve an efficient and cost-effective finishing
line. The apparatus 400 includes a platform 404, which is
preferably rigid and may be equipped with vibration dampening
mechanisms. A fixture 406 is mounted on one end of the platform
404. The fixture 406 supports a first alignment (or positional)
device 408. A support frame 410 is mounted on another end of the
platform 404, opposite the fixture 406. The support frame 410
includes support bars 412 to which a second alignment (or
positional) device 414 is attached. The first and second alignment
devices 408, 414 are spaced apart and are in opposing relation. The
fluid bearing system 200 is disposed between the first and second
alignment devices 408, 414 and coupled thereto. The fluid bearing
system 200 supports the glass sheet 202 during a finishing process
while maintaining the quality zone of the glass sheet 202 in a
pristine condition.
[0024] The first and second alignment devices 408, 414 may be
operated to adjust the position of the fluid bearing system 200, or
components thereof, as necessary, for example, relative to the
platform 404 or glass sheet 202 or processing devices 500. The
first and second alignment devices 408, 414 may be translation
stages capable of translating components of the fluid bearing
system 200 in one or more dimensions. For example, the first and
second alignment devices 408, 414 may be x-y stages, which may be
driven manually or automatically, for example, using motors, such
as DC or stepper motors or servomotors. The x-y stages may be
compound stages or may be made of individual translation stages. A
stage or actuator providing translation in fewer than two
dimensions may also be used as the alignment devices 408, 414. For
example, adjusting components of the fluid bearing system 200 along
the y-axis only may suffice. The alignment devices 408, 414 may
also incorporate tilt platforms to allow for angular adjustment of
the fluid bearing system 200.
[0025] The support frame 410 supports third and fourth translation
stages 418, 420. A processing device 500 for finishing an edge of
the glass sheet 202 may be coupled to each of the third and fourth
translation stages 418, 420. Only the processing device 500 coupled
to the third translation stage 418 is visible in the drawing. The
third and fourth translation stages 418, 420 may extend the
processing devices 500 to the fluid bearing system 200 in order to
finish the edges of the glass sheet 202 supported in the fluid
bearing system 200. A retractable bottom conveyor 424 is mounted on
the fixture 406. The bottom conveyor 424 may be used to transport
the glass sheet 202 into the fluid bearing system 200. After the
edge grippers (208 in FIGS. 2A and 2B) grip the edges of the glass
sheet 202, the bottom conveyor 424 may be retracted from the fluid
bearing system 200 to allow access to the bottom edge of the glass
sheet 202.
[0026] The processing device 500 could be any suitable device that
can be used to finish an edge of the glass sheet 202, such as a
grinding, scoring, or polishing device. Preferably, the processing
device 500 prevents contaminants generated during processing of the
edges of the glass sheet 202 from reaching the quality zone of the
glass sheet. A suitable processing device is disclosed in U.S.
Patent Application Publication No. US 2005/0090189 (Brown et al.),
the content of which is incorporated herein. FIGS. 5A and 5B show
an example of a processing device 500 disposed above the fluid
bearing system 200. The processing device 500 includes a finishing
device 502. In one example, the finishing device 502 includes a
finishing wheel 504, such as a scoring or grinding wheel, coupled
to a spindle 506. The processing device 500 further includes a
shroud 508 which encapsulates the finishing device 502. The shroud
508 includes a slot 509 through which the finishing wheel 504
accesses the edge of the glass sheet 202. Contaminants generated
during the edge finishing, e.g., glass particles and agents that
aid in finishing of the edge of the glass sheet, such as water and
other lubricants or coolant, are contained in the shroud 508. The
contaminants in the shroud 508 are evacuated through a vacuum line
(510 in FIG. 5B). The processing device 500 may also include an air
knife or a water knife 512 attached to the shroud 508 to prevent
contaminants not collected by the vacuum line 510 from
escaping.
[0027] When the edges of the glass sheet are cut using a processing
device with a shroud, the quality zone of the glass sheet is
protected from the contaminants produced during the finishing
process. The edges of the glass sheet can be finished with tools
such as grinding and scoring wheel. Other finishing devices, such
as slurry jet or nitrogen jet, may also be used in place of the
grinding wheel. A shroud may be used with the slurry or nitrogen
jet devices to enclose the edges of the glass sheet. The shroud
allows a chemical coolant or other lubricant to be used during the
finishing process. The coolant is contained within the shroud,
thereby avoiding staining of the quality zone of the glass. Use of
a coolant, such as one that is silane-based, can increase the
effectiveness of the finishing tool, e.g., the grinding wheel, and
can help heal cracks in the edges of the glass, resulting in
stronger edges. The edge debris after finishing can be cleaned by
water jet contained within the shroud.
[0028] Various arrangements of the processing devices 500 relative
to the fluid bearing system 200 are possible. FIG. 6A shows a
simplified view of an arrangement wherein processing devices 500
are provided at the top and bottom of the glass sheet 202 and are
translated along the glass sheet 202 to finish the top and bottom
edges of the glass sheet 202. The fluid bearing system 200 is
represented by phantom lines 600 to allow viewing of the glass
sheet 202. The vertical edges of the glass sheet are gripped by
edge grippers during the finishing process. To finish the vertical
edges of the glass sheet 202, the glass sheet 202 can be removed
from the fluid bearing system 200 and transported to another
process station having an identical arrangement. Prior to reaching
the next station, the glass sheet 202 may be rotated 90 degrees to
allow processing of the remaining edges of the glass sheet 202
using an identical arrangement. The rotation may be performed by a
robot that grips the glass sheet 202 in the non-quality zone.
Alternately, the edge grippers 208 can be relocated to the top and
bottom of the glass sheet 202 and the processing devices 500 can be
translated along the vertical edges of the glass sheet 202. This
would allow all the edges of the glass sheet 202 to be finished at
one station without rotating the glass sheet 202.
[0029] FIG. 6B shows another modification to the arrangement of
FIG. 6A. In this example, the edge grippers 208 which grip the
sides of the glass sheet 202 are coupled to an end-effector 602,
which is in turn coupled to a translation or positional device 604,
such as a linear slide. In this figure, the fluid bearing system
200 is also represented by phantom lines 600 to allow viewing of
the glass sheet 202 and edge grippers 208. During a finishing
process, the processing devices 500 are held stationary at the top
and bottom of the glass sheet 202 while the linear slide 604 is
operated to move the glass sheet 202 relative to the processing
devices 500 The glass sheet 202 is carried into the fluid bearing
system 200 on a first bottom conveyor 606 and leaves the fluid
bearing system 200 on a second bottom conveyor 608 for another
station having a similar or identical arrangement. The glass sheet
202 may be rotated 90 degrees prior to reaching the next station.
This example has a higher throughput because the glass sheet 202
keeps moving.
[0030] The various arrangements described above could also be
configured in a horizontal orientation rather than the vertical
orientation depicted in the figures. In a horizontal arrangement,
the fluid bearing would be horizontal. Any auxiliary equipment for
handling the glass sheet, such as bottom or overhead conveyor, edge
grippers, robot suction cups, preferably touches the glass sheet in
the non-quality area, typically 5-10 mm from the edges of the glass
sheet. Using the arrangements above, if the fluid in the fluid
bearing is liquid, the glass sheet is kept wet inside the fluid
bearing during edge finishing, which prevents particle buildup on
the glass sheet due to electrostatic charges. Keeping the glass
sheet wet also prevents fluid stains on the glass sheet.
[0031] The following finishing process examples are presented for
illustration purposes and are not to be construed as limiting the
invention as otherwise described herein.
EXAMPLE 1
[0032] A continuous glass sheet is formed by a fusion process. As
the continuous glass sheet emerges from the draw, a glass sheet of
desired size is cut from the continuous glass sheet using a
traveling anvil method (TAM). TAM involves scoring the continuous
glass sheet using a scoring assembly that travels alongside the
continuous glass sheet at a speed that matches the speed of the
continuous glass sheet. In a standard TAM cut, the scoring device
is a mechanical scoring wheel. Just before scoring the continuous
glass sheet, a robot hand applies suction cups to the continuous
glass sheet. The robot end-effectors coupled to the suction cups
travel with the moving sheet as well. Once the sheet is scored with
TAM, the robot bends the sheet to separate it from the continuous
glass sheet. The robot then hands the sheet over to an overhead
conveyor, which moves the sheet to another station. In this
example, a set of rollers (or edge guides) grip the edges of the
continuous glass sheet as the continuous glass sheet passes through
the draw, as is well-known in the art. In this case, the next
station is a station where vertical bead removal (VBS) occurs,
i.e., trimming of the vertical edges of the glass to remove beads.
Typically, the beads are removed before the glass sheet is cold;
otherwise, too much stress may set into the glass sheet. VBS is not
needed if the edges of the continuous glass sheet do not pass
through rollers (or edge guides) in the draw.
EXAMPLE 2
[0033] A glass sheet as prepared in EXAMPLE 1 is processed on a
finishing line including one or more of the fluid bearing system of
the invention. The finishing process includes cutting the glass
sheet to size using a thermal shock cutting process. Thermal shock
cutting processes are described in, for example, U.S. Pat. Nos.
6713720, 6204472, 6327875, 6407360, 6420678, 6541730, and 6112967,
the tutorial contents of which are incorporated herein by
reference. In general, the thermal shock cutting process involves
heating the glass sheet along a narrow line using a heat source
such as a laser or plasma torch. Heating of the glass sheet along
the narrow line is immediately followed by rapid cooling of the
glass sheet along the narrow line. The heating and cooling cycle
creates a thermal shock in the glass in the vicinity of the narrow
line, which results in a crack that propagates along the narrow
line. The glass sheet separates or can be easily separated from the
glass sheet along the crack.
[0034] The glass sheet may be supported on an air bearing during
the thermal shock cutting process. Air bearings can be simple,
e.g., with holes blowing air to suspend the glass or air/vacuum
combination such as NEW WAY.RTM. air bearings, available from New
Way Air Bearings, Aston, Pa., or Core Flow air bearings.
Alternatively, the fluid bearing system described above may be used
with air as the fluid. After cutting the glass sheet to size, the
edges of the glass sheet are finished while supporting the glass
sheet in the fluid bearing system. A first set of opposite edges of
the glass sheet may be finished (cut and ground/polished)
simultaneously. Then, the remaining set of opposite edges of the
glass sheet may also be finished simultaneously with or without
rotating the glass sheet. The glass sheet is then washed because
TAM and VBS in EXAMPLE 1 are not clean. After washing the glass
sheet, the glass sheet is dried using an air knife. The glass sheet
is then inspected. After inspection, the glass sheet may be coated
with a protective coating. The glass sheet is then packed for
shipping and/or storage.
EXAMPLE 3
[0035] A glass sheet is finished as in EXAMPLE 2, except that the
glass sheet is cut to size while supporting the glass sheet in a
fluid bearing system and using processing devices with shroud.
EXAMPLE 4
[0036] A glass sheet is prepared as in EXAMPLE 1, except that TAM
cut and VBS is by thermal shock process. The thermal shock process
is clean and does not produce glass chips that can contaminate the
quality zone of the glass sheet. The glass sheet is then finished
as in EXAMPLE 2 or EXAMPLE 3, except that final washing of glass
sheet is not needed because TAM cut and VBS are clean.
[0037] The invention typically provides the following advantages.
Extensive washing and drying of the glass sheet typically
associated with prior art finishing processes can be avoided where
TAM cut and VBS are clean as described in, for example, EXAMPLE 4
above. The finishing processes described above can be easily
integrated with fusion processes. The fluid bearing system provides
support to the glass sheet during the edge finishing process
without contacting the quality zone of the glass sheet. The fluid
bearing system adds stiffness to the glass, enabling more precise
cut and preventing deformation during edge finishing of the glass
sheet. The fluid bearing system can be used to control the
temperature of the glass sheet to maximize edge processing
efficiency. The footprint of the processing line in the vertical
orientation is significantly reduced over a horizontal orientation.
Contamination of the quality zone of the glass sheet while the
glass sheet is in the fluid bearing system is avoided by shrouding
the edges of the glass sheet during edge processing.
[0038] While the invention has been described with respect to a
limited number of embodiments, those skilled in the art, having
benefit of this disclosure, will appreciate that other embodiments
can be devised which do not depart from the scope of the invention
as disclosed herein. Accordingly, the scope of the invention should
be limited only by the attached claims.
* * * * *